WorldWideScience

Sample records for climate-related extreme events

  1. The role of social inequalities for the vulnerability to climate related extreme weather events

    OpenAIRE

    NEHER FRANK; MIOLA Apollonia

    2015-01-01

    This report analyses the differential impact of extreme weather events in the presence of social inequalities. It hypothesizes that social inequalities affect vulnerability and resilience through its impact on the capacity to cope and empirically analyses the differential impact of extreme weather events in the presence of social inequalities. To sidestep the methodological difficulties of quantifying vulnerability or resilience, the relation between different inequalities and disaster fatali...

  2. Estimating least-developed countries’ vulnerability to climate-related extreme events over the next 50 years

    OpenAIRE

    Patt, A. G.; Tadross, M.; Nussbaumer, P; Asante, K.; Metzger, M.J.; Rafael, J.; Goujon, A.; Brundrit, G.

    2010-01-01

    When will least developed countries be most vulnerable to climate change, given the influence of projected socio-economic development? The question is important, not least because current levels of international assistance to support adaptation lag more than an order of magnitude below what analysts estimate to be needed, and scaling up support could take many years. In this paper, we examine this question using an empirically derived model of human losses to climate-related extreme events, ...

  3. Assessing current and future impacts of climate-related extreme events. The case of Bangladesh

    OpenAIRE

    Hochrainer-Stigler, S.; Mechler, R.; Pflug, G.

    2010-01-01

    Extreme events and options for managing these risks are receiving increasing attention in research and policy. In order to cost these extremes, a standard approach is to use Integrated Assessment Models with global or regional resolution and represent risk using add-on damage functions that are based on observed impacts and contingent on gradual temperature increase. Such assessments generally find that economic development and population growth are likely to be the major drivers of natural d...

  4. Estimating least-developed countries' vulnerability to climate-related extreme events over the next 50 years.

    Science.gov (United States)

    Patt, Anthony G; Tadross, Mark; Nussbaumer, Patrick; Asante, Kwabena; Metzger, Marc; Rafael, Jose; Goujon, Anne; Brundrit, Geoff

    2010-01-26

    When will least developed countries be most vulnerable to climate change, given the influence of projected socio-economic development? The question is important, not least because current levels of international assistance to support adaptation lag more than an order of magnitude below what analysts estimate to be needed, and scaling up support could take many years. In this paper, we examine this question using an empirically derived model of human losses to climate-related extreme events, as an indicator of vulnerability and the need for adaptation assistance. We develop a set of 50-year scenarios for these losses in one country, Mozambique, using high-resolution climate projections, and then extend the results to a sample of 23 least-developed countries. Our approach takes into account both potential changes in countries' exposure to climatic extreme events, and socio-economic development trends that influence countries' own adaptive capacities. Our results suggest that the effects of socio-economic development trends may begin to offset rising climate exposure in the second quarter of the century, and that it is in the period between now and then that vulnerability will rise most quickly. This implies an urgency to the need for international assistance to finance adaptation. PMID:20080585

  5. Solar extreme events

    OpenAIRE

    Hudson, Hugh S.

    2015-01-01

    Solar flares and CMEs have a broad range of magnitudes. This review discusses the possibility of "extreme events," defined as those with magnitudes greater than have been seen in the existing historical record. For most quantitative measures, this direct information does not extend more than a century and a half into the recent past. The magnitude distributions (occurrence frequencies) of solar events (flares/CMEs) typically decrease with the parameter measured or inferred (peak flux, mass, e...

  6. DADA: Data Assimilation for the Detection and Attribution of Weather- and Climate-related Events

    OpenAIRE

    Hannart, Alexis; Carrassi, Alberto; Bocquet, Marc; Ghil, Michael; Naveau, Philippe; PULIDO, Manuel; Ruiz, Juan; TANDEO, Pierre

    2015-01-01

    We describe a new approach allowing for systematic causal attribution of weather and climate-related events, in near-real time. The method is purposely designed to facilitate its implementation at meteorological centers by relying on data treatments that are routinely performed when numerically forecasting the weather. Namely, we show that causal attribution can be obtained as a by-product of so-called data assimilation procedures that are run on a daily basis to update the meteorological mod...

  7. Solar extreme events

    CERN Document Server

    Hudson, Hugh S

    2015-01-01

    Solar flares and CMEs have a broad range of magnitudes. This review discusses the possibility of "extreme events," defined as those with magnitudes greater than have been seen in the existing historical record. For most quantitative measures, this direct information does not extend more than a century and a half into the recent past. The magnitude distributions (occurrence frequencies) of solar events (flares/CMEs) typically decrease with the parameter measured or inferred (peak flux, mass, energy etc. Flare radiation fluxes tend to follow a power law slightly flatter than $S^{-2}$, where S represents a peak flux; solar particle events (SPEs) follow a still flatter power law up to a limiting magnitude, and then appear to roll over to a steeper distribution, which may take an exponential form or follow a broken power law. This inference comes from the terrestrial $^{14}$C record and from the depth dependence of various radioisotope proxies in the lunar regolith and in meteorites. Recently major new observation...

  8. Climate Networks and Extreme Events

    Science.gov (United States)

    Kurths, J.

    2014-12-01

    We analyse some climate dynamics from a complex network approach. This leads to an inverse problem: Is there a backbone-like structure underlying the climate system? For this we propose a method to reconstruct and analyze a complex network from data generated by a spatio-temporal dynamical system. This approach enables us to uncover relations to global circulation patterns in oceans and atmosphere. The global scale view on climate networks offers promising new perspectives for detecting dynamical structures based on nonlinear physical processes in the climate system. Moreover, we evaluate different regional climate models from this aspect. This concept is also applied to Monsoon data in order to characterize the regional occurrence of extreme rain events and its impact on predictability. Changing climatic conditions have led to a significant increase in magnitude and frequency of spatially extensive extreme rainfall events in the eastern Central Andes of South America. These events impose substantial natural hazards for population, economy, and ecology by floods and landslides. For example, heavy floods in Bolivia in early 2007 affected more than 133.000 households and produced estimated costs of 443 Mio. USD. Here, we develop a general framework to predict extreme events by combining a non-linear synchronization technique with complex networks. We apply our method to real-time satellite-derived rainfall data and are able to predict a large amount of extreme rainfall events. Our study reveals a linkage between polar and subtropical regimes as responsible mechanism: Extreme rainfall in the eastern Central Andes is caused by the interplay of northward migrating frontal systems and a low-level wind channel from the western Amazon to the subtropics, providing additional moisture. Frontal systems from the Antarctic thus play a key role for sub-seasonal variability of the South American Monsoon System.

  9. On causality of extreme events

    CERN Document Server

    Zanin, Massimiliano

    2016-01-01

    Multiple metrics have been developed to detect causality relations between data describing the elements constituting complex systems, all of them considering their evolution through time. Here we propose a metric able to detect causality within static data sets, by analysing how extreme events in one element correspond to the appearance of extreme events in a second one. The metric is able to detect both linear and non-linear causalities; to analyse both cross-sectional and longitudinal data sets; and to discriminate between real causalities and correlations caused by confounding factors. We validate the metric through synthetic data, dynamical and chaotic systems, and data representing the human brain activity in a cognitive task.

  10. Understanding the role of compound events in climate extremes

    Science.gov (United States)

    Leonard, Michael; Westra, Seth; Phatak, Aloke; Lambert, Martin; van den Hurk, Bart; McInness, Kathleen; Risby, James; Schuster, Sandra; Jakob, Doerte; Stafford-Smith, Mark

    2013-04-01

    Climate variables give rise to hazards such as cyclones, floods and fires where an extreme impact is the result of a combination of variables rather than any one variable being in an extreme state in isolation. The combination of variables is termed a compound event and the nature of any given compound event will depend upon the variety of physical variables, the range of spatial and temporal scales over which they are linked, the strength of dependence between processes, and the interest of the stakeholder in defining the impact. Modelling compound events is a large, complex and inter-disciplinary undertaking and to facilitate this task influence diagrams are proposed for better defining, mapping, analysing, modelling and communicating the behaviour of the compound event. Ultimately, the greater appreciation of compound events will lead to greater insight and a changed perspective on how impact risks are associated with climate related hazards.

  11. Extreme Events in Nature and Society

    CERN Document Server

    Albeverio, Sergio; Kantz, Holger

    2006-01-01

    Significant, and usually unwelcome, surprises, such as floods, financial crisis, epileptic seizures, or material rupture, are the topics of Extreme Events in Nature and Society. The book, authored by foremost experts in these fields, reveals unifying and distinguishing features of extreme events, including problems of understanding and modelling their origin, spatial and temporal extension, and potential impact. The chapters converge towards the difficult problem of anticipation: forecasting the event and proposing measures to moderate or prevent it. Extreme Events in Nature and Society will interest not only specialists, but also the general reader eager to learn how the multifaceted field of extreme events can be viewed as a coherent whole.

  12. The National Extreme Events Data and Research Center (NEED)

    Science.gov (United States)

    Gulledge, J.; Kaiser, D. P.; Wilbanks, T. J.; Boden, T.; Devarakonda, R.

    2014-12-01

    The Climate Change Science Institute at Oak Ridge National Laboratory (ORNL) is establishing the National Extreme Events Data and Research Center (NEED), with the goal of transforming how the United States studies and prepares for extreme weather events in the context of a changing climate. NEED will encourage the myriad, distributed extreme events research communities to move toward the adoption of common practices and will develop a new database compiling global historical data on weather- and climate-related extreme events (e.g., heat waves, droughts, hurricanes, etc.) and related information about impacts, costs, recovery, and available research. Currently, extreme event information is not easy to access and is largely incompatible and inconsistent across web sites. NEED's database development will take into account differences in time frames, spatial scales, treatments of uncertainty, and other parameters and variables, and leverage informatics tools developed at ORNL (i.e., the Metadata Editor [1] and Mercury [2]) to generate standardized, robust documentation for each database along with a web-searchable catalog. In addition, NEED will facilitate convergence on commonly accepted definitions and standards for extreme events data and will enable integrated analyses of coupled threats, such as hurricanes/sea-level rise/flooding and droughts/wildfires. Our goal and vision is that NEED will become the premiere integrated resource for the general study of extreme events. References: [1] Devarakonda, Ranjeet, et al. "OME: Tool for generating and managing metadata to handle BigData." Big Data (Big Data), 2014 IEEE International Conference on. IEEE, 2014. [2] Devarakonda, Ranjeet, et al. "Mercury: reusable metadata management, data discovery and access system." Earth Science Informatics 3.1-2 (2010): 87-94.

  13. Extreme events: dynamics, statistics and prediction

    OpenAIRE

    M. Ghil; Yiou, P.; S. Hallegatte; B. D. Malamud; Naveau, P.; A. Soloviev; Friederichs, P.; Keilis-Borok, V.; Kondrashov, D.; V. Kossobokov; Mestre, O.; Nicolis, C.; Rust, H. W.; P. Shebalin; Vrac, M.

    2011-01-01

    We review work on extreme events, their causes and consequences, by a group of European and American researchers involved in a three-year project on these topics. The review covers theoretical aspects of time series analysis and of extreme value theory, as well as of the deterministic modeling of extreme events, via continuous and discrete dynamic models. The applications include climatic, seismic and socio-economic events, along with their prediction.

    Two important resul...

  14. Extreme weather events and infectious disease outbreaks

    OpenAIRE

    Anthony J McMichael

    2015-01-01

    Human-driven climatic changes will fundamentally influence patterns of human health, including infectious disease clusters and epidemics following extreme weather events. Extreme weather events are projected to increase further with the advance of human-driven climate change. Both recent and historical experiences indicate that infectious disease outbreaks very often follow extreme weather events, as microbes, vectors and reservoir animal hosts exploit the disrupted social and environmental c...

  15. Extreme events: The art of attribution

    Science.gov (United States)

    Otto, Friederike E. L.

    2016-04-01

    A high-impact weather event that occurred at the end of a decade of weather extremes led to the emergence of extreme event attribution science. The challenge is now to move on to assessing the actual risks, rather than simply attributing meteorological variables to climate change.

  16. Reactions to extreme events: moving threshold model

    CERN Document Server

    Altmann, E G; Kantz, H

    2006-01-01

    In spite of precautions to avoid the harmful effects of extreme events, we experience recurrently phenomena that overcome the preventive barriers. These barriers usually increase drastically right after the occurrence of such extreme events, but steadily decay in their absence. In this paper we consider a simple model that mimics the evolution of the protection barriers to study the efficiency of the system's reaction to extreme events and how it changes our perception of the sequence of extreme events itself. We obtain that the usual method of fighting extreme events introduces a periodicity in their occurrence and is generally less efficient than the use of a constant barrier. On the other hand, it shows a good adaptation to the presence of slow non-stationarities.

  17. Extreme hydrological events and security

    Science.gov (United States)

    Kundzewicz, Z. W.; Matczak, P.

    2015-06-01

    Economic losses caused by hydrological extremes - floods and droughts - have been on the rise, worldwide. Hydrological extremes jeopardize human security and cause serious threats to human life and welfare and societal livelihood. Floods and droughts can undermine societies' security, understood as freedom from threat and the ability of societies to maintain their independent identity and their functional integrity against forces of change. Several dimensions of security are reviewed in the context of hydrological extremes. Floods and droughts pose a burden and serious challenges to the state, responsible to sustain economic development, societal and environmental security - the maintenance of ecosystem services, on which a society depends. It is shown that reduction of risk of hydrological disasters improves human security.

  18. Scaling in the Timing of Extreme Events

    OpenAIRE

    Corral, Alvaro

    2014-01-01

    Extreme events can come either from point processes, when the size or energy of the events is above a certain threshold, or from time series, when the intensity of a signal surpasses a threshold value. We are particularly concerned by the time between these extreme events, called respectively waiting time and quiet time. If the thresholds are high enough it is possible to justify the existence of scaling laws for the probability distribution of the times as a function of the threshold value, ...

  19. Hydrological EXtreme Events in Changing Climate: The HEX Events project

    NARCIS (Netherlands)

    Benito, G.; Macklin, M.G.; Cohen, K.M.; Herget, J.

    2013-01-01

    Chronological control of Late Pleistocene and Holocene fluvial archives has much improved during the past decades, and this is renewing their use in order to improve records of extreme hydrological events worldwide. A extreme hydrological event is here defined in the sense given by Gregroy et al., (

  20. Extreme weather events and infectious disease outbreaks.

    Science.gov (United States)

    McMichael, Anthony J

    2015-01-01

    Human-driven climatic changes will fundamentally influence patterns of human health, including infectious disease clusters and epidemics following extreme weather events. Extreme weather events are projected to increase further with the advance of human-driven climate change. Both recent and historical experiences indicate that infectious disease outbreaks very often follow extreme weather events, as microbes, vectors and reservoir animal hosts exploit the disrupted social and environmental conditions of extreme weather events. This review article examines infectious disease risks associated with extreme weather events; it draws on recent experiences including Hurricane Katrina in 2005 and the 2010 Pakistan mega-floods, and historical examples from previous centuries of epidemics and 'pestilence' associated with extreme weather disasters and climatic changes. A fuller understanding of climatic change, the precursors and triggers of extreme weather events and health consequences is needed in order to anticipate and respond to the infectious disease risks associated with human-driven climate change. Post-event risks to human health can be constrained, nonetheless, by reducing background rates of persistent infection, preparatory action such as coordinated disease surveillance and vaccination coverage, and strengthened disaster response. In the face of changing climate and weather conditions, it is critically important to think in ecological terms about the determinants of health, disease and death in human populations. PMID:26168924

  1. Hydrological EXtreme Events in Changing Climate: The HEX Events project

    OpenAIRE

    G. Benito; Macklin, M. G.; Cohen, K.M.; J. Herget

    2013-01-01

    Chronological control of Late Pleistocene and Holocene fluvial archives has much improved during the past decades, and this is renewing their use in order to improve records of extreme hydrological events worldwide. A extreme hydrological event is here defined in the sense given by Gregroy et al., (2006), meaning any past process or phenomena related to the hydrological cycle (e.g. rainfall, runoff, snowmelt, flood, water recharge) with a magnitude higher/lower than the mean and probably abov...

  2. Overview of the biology of extreme events

    Science.gov (United States)

    Gutschick, V. P.; Bassirirad, H.

    2008-12-01

    Extreme events have, variously, meteorological origins as in heat waves or precipitation extremes, or biological origins as in pest and disease eruptions (or tectonic, earth-orbital, or impact-body origins). Despite growing recognition that these events are changing in frequency and intensity, a universal model of ecological responses to these events is slow to emerge. Extreme events, negative and positive, contrast with normal events in terms of their effects on the physiology, ecology, and evolution of organisms, hence also on water, carbon, and nutrient cycles. They structure biogeographic ranges and biomes, almost surely more than mean values often used to define biogeography. They are challenging to study for obvious reasons of field-readiness but also because they are defined by sequences of driving variables such as temperature, not point events. As sequences, their statistics (return times, for example) are challenging to develop, as also from the involvement of multiple environmental variables. These statistics are not captured well by climate models. They are expected to change with climate and land-use change but our predictive capacity is currently limited. A number of tools for description and analysis of extreme events are available, if not widely applied to date. Extremes for organisms are defined by their fitness effects on those organisms, and are specific to genotypes, making them major agents of natural selection. There is evidence that effects of extreme events may be concentrated in an extended recovery phase. We review selected events covering ranges of time and magnitude, from Snowball Earth to leaf functional loss in weather events. A number of events, such as the 2003 European heat wave, evidence effects on water and carbon cycles over large regions. Rising CO2 is the recent extreme of note, for its climatic effects and consequences for growing seasons, transpiration, etc., but also directly in its action as a substrate of photosynthesis

  3. Extreme precipitation events in a changing climate

    International Nuclear Information System (INIS)

    Canada's natural environment and built infrastructure are affected significantly by extreme weather events, with repercussions such as economic losses. The purpose of this presentation was to research whether these losses are due to greater societal vulnerability or climatic extremes or both, and to determine whether engineering design codes and standards need to be changed to ensure that infrastructure, such as dams, can withstand future climatic extremes. Environment Canada maintains long term climate and water observing networks and uses climate data in the development of building codes and engineering design standards and practices. Because of the variable nature of precipitation, the range of spatial scales, climate system influences and the importance of local topography on precipitation occurrence and amount, analyzing historical trends and making future projections for precipitation, particularly extremes, are challenging. This presentation discussed historical climate trends and future projections with reference to changes temperature, precipitation and precipitation extremes. In addition, extreme weather events and recent trends were discussed together with human influence on trends and projections. The presentation demonstrated how the climate in Canada has varied during the period of instrumental records. Future predictions for precipitation extremes were developed using climate models and statistical downscaling. The presentation also highlighted atmospheric hazards information under development for emergency preparedness and disaster management planning. It was concluded that future climate changes are inevitable and will likely affect the frequency of heavy precipitation events. 14 refs., 1 tab., 19 figs

  4. Probabilistic analysis of extreme wind events

    Energy Technology Data Exchange (ETDEWEB)

    Chaviaropoulos, P.K. [Center for Renewable Energy Sources (CRES), Pikermi Attikis (Greece)

    1997-12-31

    A vital task in wind engineering and meterology is to understand, measure, analyse and forecast extreme wind conditions, due to their significant effects on human activities and installations like buildings, bridges or wind turbines. The latest version of the IEC standard (1996) pays particular attention to the extreme wind events that have to be taken into account when designing or certifying a wind generator. Actually, the extreme wind events within a 50 year period are those which determine the ``static`` design of most of the wind turbine components. The extremes which are important for the safety of wind generators are those associated with the so-called ``survival wind speed``, the extreme operating gusts and the extreme wind direction changes. A probabilistic approach for the analysis of these events is proposed in this paper. Emphasis is put on establishing the relation between extreme values and physically meaningful ``site calibration`` parameters, like probability distribution of the annual wind speed, turbulence intensity and power spectra properties. (Author)

  5. Extreme events: dynamics, statistics and prediction

    Directory of Open Access Journals (Sweden)

    M. Ghil

    2011-05-01

    Full Text Available We review work on extreme events, their causes and consequences, by a group of European and American researchers involved in a three-year project on these topics. The review covers theoretical aspects of time series analysis and of extreme value theory, as well as of the deterministic modeling of extreme events, via continuous and discrete dynamic models. The applications include climatic, seismic and socio-economic events, along with their prediction.

    Two important results refer to (i the complementarity of spectral analysis of a time series in terms of the continuous and the discrete part of its power spectrum; and (ii the need for coupled modeling of natural and socio-economic systems. Both these results have implications for the study and prediction of natural hazards and their human impacts.

  6. Predictability of extreme events in social media

    CERN Document Server

    Miotto, José M

    2014-01-01

    It is part of our daily social-media experience that seemingly ordinary items (videos, news, publications, etc.) unexpectedly gain an enormous amount of attention. Here we investigate how unexpected these events are. We propose a method that, given some information on the items, quantifies the predictability of events, i.e., the potential of identifying in advance the most successful items defined as the upper bound for the quality of any prediction based on the same information. Applying this method to different data, ranging from views in YouTube videos to posts in Usenet discussion groups, we invariantly find that the predictability increases for the most extreme events. This indicates that, despite the inherently stochastic collective dynamics of users, efficient prediction is possible for the most extreme events.

  7. Will Extreme Climatic Events Facilitate Biological Invasions?

    OpenAIRE

    Diez, Jeffrey M; D'Antonio, Carla M; Dukes, Jeffrey S; Grosholz, Edwin D.; Olden, Julian D.; Sorte, Cascade JB; Dana M. Blumenthal; Bradley, Bethany A; Early, Regan; Ibáñez, Inés; Jones, Sierra J; Lawler, Joshua J.; Miller, Luke P.

    2012-01-01

    Extreme climatic events (ECEs) – such as unusual heat waves, hurricanes, floods, and droughts – can dramatically affect ecological and evolutionary processes, and these events are projected to become more frequent and more intense with ongoing climate change. However, the implications of ECEs for biological invasions remain poorly understood. Using concepts and empirical evidence from invasion ecology, we identify mechanisms by which ECEs may influence the invasion process, from initial intro...

  8. A Fourier analysis of extreme events

    DEFF Research Database (Denmark)

    Mikosch, Thomas Valentin; Zhao, Yuwei

    2014-01-01

    The extremogram is an asymptotic correlogram for extreme events constructed from a regularly varying stationary sequence. In this paper, we define a frequency domain analog of the correlogram: a periodogram generated from a suitable sequence of indicator functions of rare events. We derive basic ...... properties of the periodogram such as the asymptotic independence at the Fourier frequencies and use this property to show that weighted versions of the periodogram are consistent estimators of a spectral density derived from the extremogram....

  9. Extreme Events: Dynamics, Statistics and Prediction

    Science.gov (United States)

    Ghil, M.

    2013-05-01

    In this talk, I will review some recent work on extreme events, their causes and consequences. The review covers theoretical aspects of time series analysis and of extreme value theory, as well as of the deterministic modeling of extreme events, via continuous and discrete dynamic models. The applications include climatic, seismic and socio-economic events, along with their prediction. Two important results refer to (i) the complementarity of spectral analysis of a time series in terms of the continuous and the discrete part of its power spectrum; and (ii) the need for coupled modeling of natural and socio-economic systems. Both these results have implications for the study and prediction of natural hazards and their human impacts. US GDP data used in validating the vulnerability paradox found in a Non-Equilibrium Dynamical Model (NEDyM) for studying the impact of extreme events on a dynamic economy. The paradoxical result is that natural hazards affect more strongly an economy in expansion than when it is in a recession. The connection to the macroeconomic data is given by fluctuation-dissipation theory.

  10. Urbanization, Extreme Events, and Health: The Case for Systems Approaches in Mitigation, Management, and Response.

    Science.gov (United States)

    Siri, José Gabriel; Newell, Barry; Proust, Katrina; Capon, Anthony

    2016-03-01

    Extreme events, both natural and anthropogenic, increasingly affect cities in terms of economic losses and impacts on health and well-being. Most people now live in cities, and Asian cities, in particular, are experiencing growth on unprecedented scales. Meanwhile, the economic and health consequences of climate-related events are worsening, a trend projected to continue. Urbanization, climate change and other geophysical and social forces interact with urban systems in ways that give rise to complex and in many cases synergistic relationships. Such effects may be mediated by location, scale, density, or connectivity, and also involve feedbacks and cascading outcomes. In this context, traditional, siloed, reductionist approaches to understanding and dealing with extreme events are unlikely to be adequate. Systems approaches to mitigation, management and response for extreme events offer a more effective way forward. Well-managed urban systems can decrease risk and increase resilience in the face of such events. PMID:26219559

  11. Community Risk and Resilience to Climate Hazards and Extreme Events in the Turtle Region of Trinidad

    OpenAIRE

    HOLMES, TISHA

    2015-01-01

    This dissertation examines the socio-spatial impacts of climate-related hazards and extreme weather events and associated responses in the Turtle Region of Trinidad & Tobago. The Turtle Region supports a growing eco-tourism industry centered on excursions to remote pristine beaches, hiking trails, waterfalls, and the annual migration of female Leatherback turtles to lay their eggs on natal beaches. The Turtle Region also experiences rapid rates of coastal erosion and severe weather related ev...

  12. Biological Extreme Events - Past, Present, and Future

    Science.gov (United States)

    Gutschick, V. P.

    2010-12-01

    Biological extreme events span wide ranges temporally and spatially and in type - population dieoffs, extinctions, ecological reorganizations, changes in biogeochemical fluxes, and more. Driving variables consist in meteorology, tectonics, orbital changes, anthropogenic changes (land-use change, species introductions, reactive N injection into the biosphere), and evolution (esp. of diseases). However, the mapping of extremes in the drivers onto biological extremes as organismal responses is complex, as laid out originally in the theoretical framework of Gutschick and BassiriRad (New Phytologist [2003] 100:21-42). Responses are nonlinear and dependent on (mostly unknown and) complex temporal sequences - often of multiple environmental variables. The responses are species- and genotype specific. I review extreme events over from past to present over wide temporal scales, while noting that they are not wholly informative of responses to the current and near-future drivers for at least two reasons: 1) the current combination of numerous environmental extremes - changes in CO2, temperature, precipitation, reactive N, land fragmentation, O3, etc. -is unprecedented in scope, and 2) adaptive genetic variation for organismal responses is constrained by poorly-characterized genetic structures (in organisms and populations) and by loss of genetic variation by genetic drift over long periods. We may expect radical reorganizations of ecosystem and biogeochemical functions. These changes include many ecosystem services in flood control, crop pollination and insect/disease control, C-water-mineral cycling, and more, as well as direct effects on human health. Predictions of such changes will necessarily be very weak in the critical next few decades, given the great deal of observation, experimentation, and theory construction that will be necessary, on both organisms and drivers. To make the research efforts most effective will require extensive, insightful planning, beginning

  13. Thunderstorms as extreme climate event in Serbia

    Directory of Open Access Journals (Sweden)

    Anđelković Goran

    2009-01-01

    Full Text Available Humankind has been exposed to climate extremes from the very beginning of its existence. Today, prevention and mitigation of natural catastrophes have become a priority for International Union and World Meteorological Organization. Atmospheric electrical discharges and thunders represent an event characteristic of our part of the world in the warm half of a year. This climate event pose a danger to human life and material goods, so this work discusses approximate number of days with thunder and the absolutely highest number of days with thunder in Serbia in the period from 1995 to 2005.

  14. Climate change and extreme events in weather

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    monsoon and b) tropical cyclones. Basically the climate of India is domi- nated by the south west monsoon season which accounts for about 75% of the annual rainfall. The extreme weather events occur over India are: Floods, Droughts, Tropical Cyclones..., 52, 35, 092 people in 4962 villages were af- fected. Standing crops in 2,13,184 hectares of land were badly affected. Of all the major natural disasters, droughts account for significant damages even though the number of deaths is insignificant...

  15. Astrophysical Effects of Extreme Gravitational Lensing Events

    CERN Document Server

    Wang, Y; Wang, Yun; Turner, Edwin L.

    1998-01-01

    Every astrophysical object (dark or not) is a gravitational lens, as well as a receiver/observer of the light from sources lensed by other objects in its neighborhood. For a given pair of source and lens, there is a thin on-axis tubelike volume behind the lens in which the radiation flux from the source is greatly increased due to gravitational lensing. Any objects which pass through such a thin tube or beam will experience strong bursts of radiation, i.e., Extreme Gravitational Lensing Events (EGLEs). We have studied the physics and statistics of EGLEs. EGLEs may have interesting astrophysical effects, such as the destruction of dust grains, ignition of masers, etc. Here we illustrate the possible astrophysical effects of EGLEs with one specific example, the destruction of dust grains in globular clusters.

  16. Lower extremity corrective reactions to slip events.

    Science.gov (United States)

    Cham, R; Redfern, M S

    2001-11-01

    A significant number of injuries in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether the outcome of a slip will be recovery or a fall. The goal of this study was to examine lower extremity joint moments and postural adjustments for experimental evidence of corrective strategies evoked during slipping in an attempt to prevent falling. Sixteen subjects walked onto a possibly oily vinyl tile floor, while ground reaction forces and body motion were recorded at 350 Hz. The onset of corrective reactions by the body in an attempt to recover from slips became evident at about 25% of stance and continued until about 45% into stance, i.e. on average between 190 and 350 ms after heel contact. These reactions included increased flexion moment at the knee and extensor activity at the hip. The ankle, on the other hand, acted as a passive joint (no net moment) during fall trials. Joint kinematics showed increased knee flexion and forward rotation of the shank in an attempt to bring the foot back towards the body. Once again, the ankle kinematics appeared to play a less dominant role (compared to the knee) in recovery attempts. This study indicates that humans generate corrective reactions to slips that are different than previously reported responses to standing perturbations translating the supporting surface. PMID:11672718

  17. Extreme temperature events analyzed with Fast Fourier Transform

    OpenAIRE

    Saa Requejo, Antonio; Tarquis Alfonso, Ana Maria; García Moreno, Rosario; Diaz Alvarez, Maria Cruz; Burgaz, Fernando

    2011-01-01

    Extreme weather and climate events have received increased attention in the last few years, due to the often large loss of agriculture business and exponentially increasing costs associated with them and insurance planning. This increased attention raises the question as to whether extreme weather and climate events are truly increasing, whether this is only a perceived increase exacerbated by enhanced media coverage, or both. There are a number of ways extreme climate events can be defined, ...

  18. Spatiotemporal Chaos Induces Extreme Events in an Extended Microcavity Laser

    Science.gov (United States)

    Selmi, F.; Coulibaly, S.; Loghmari, Z.; Sagnes, I.; Beaudoin, G.; Clerc, M. G.; Barbay, S.

    2016-01-01

    Extreme events such as rogue waves in optics and fluids are often associated with the merging dynamics of coherent structures. We present experimental and numerical results on the physics of extreme event appearance in a spatially extended semiconductor microcavity laser with an intracavity saturable absorber. This system can display deterministic irregular dynamics only, thanks to spatial coupling through diffraction of light. We have identified parameter regions where extreme events are encountered and established the origin of this dynamics in the emergence of deterministic spatiotemporal chaos, through the correspondence between the proportion of extreme events and the dimension of the strange attractor.

  19. Energy Infrastructure and Extreme Events (Invited)

    Science.gov (United States)

    Wakimoto, R. M.

    2013-12-01

    The country's energy infrastructure is sensitive to the environment, especially extreme events. Increasing global temperatures, intense storms, and space weather have the potential to disrupt energy production and transport. It can also provide new opportunities as illustrated by the opening of the Northwest Passage. The following provides an overview of some of the high impacts of major geophysical events on energy production and transport. Future predictions of hurricanes suggest that we can expect fewer storms but they will be associated with stronger winds and more precipitation. The winds and storm surge accompanying hurricane landfall along the Gulf States has had a major impact on the coastal energy infrastructure and the oil/natural gas platforms. The impact of these surges will increase with predicted sea level rise. Hurricane Katrina caused damage to crude oil pipelines and refineries that reduced oil production by 19% for the year. The disruption that can occur is not necessarily linked with the maximum winds of the tropical storm as recently shown by Hurricane Sandy which was classified as a ';post-tropical cyclone' during landfall. Another intense circulation, the tornado, can also cause power outages and network breaks from high winds that can topple power poles or damage power lines from fallen trees. Fortunately, the Moore tornado, rated EF5, did not have a major impact on the oil and gas infrastructure in Oklahoma. The impact of earthquakes and tsunamis on energy was illustrated in Japan in 2011 with the shutdown of the Fukushima Daiichi plant. Other studies have suggested that there are areas in the United States where the energy services are highly vulnerable to major earthquakes that would disrupt electrical and gas networks for extended periods of time. Seismic upgrades to the energy infrastructure would help mitigate the impact. In 1859, a coronal mass ejection triggered a geomagnetic storm that disrupted communication wires around the world

  20. A Fourier analysis of extremal events

    DEFF Research Database (Denmark)

    Zhao, Yuwei

    extremal periodogram. The extremal periodogram shares numerous asymptotic properties with the periodogram of a linear process in classical time series analysis: the asymptotic distribution of the periodogram ordinates at the Fourier frequencies have a similar form and smoothed versions of the periodogram...

  1. Extreme seawater compositions during Oceanic Anoxic Events

    Science.gov (United States)

    Cohen, A.; Bottini, C.; Dickson, A. J.; Izon, G. J.; Coe, A. L.

    2012-12-01

    For almost the entire duration of the Phanerozoic, the oceans have remained well oxygenated and highly conducive to the development of animal and plant life. However, there have been relatively brief intervals, known as Oceanic Anoxic Events (OAEs), when a very significant expansion of low-oxygen regions occurred throughout the world's oceans. OAEs were characterised by highly atypical seawater chemistry, as reflected in the chemical and isotopic compositions of contemporaneous sediments and fossil remains. These oxygen-deficient intervals also exerted profound pressures on many marine species as indicated by major changes in species populations and distributions. High-resolution chemical and isotopic data recovered from marine sediments and sedimentary rocks, together with biotic information, provide us with the best means of understanding the significance of OAEs and their place in the evolution of the Earth system. We present new Mo- and Os-isotope and geochemical data from OAE 1a (early Cretaceous), which help define how this event evolved in relation to the other major environmental parameters - including global warming, continental weathering and Ontong-Java volcanism - of that time. We compare these new observations with published results from other Mesozoic OAEs and the PETM. Recently published Os-isotope data from DSDP site 463 (mid-Pacific) [1] and northern Italy [1, 2] show that the Os budget of the oceans was dominated for a period of c. 880 ka during OAE 1a by the hydrothermal flux of unradiogenic Os from the Ontong-Java province. The observation of identical Os-isotope compositions at these two very distant sites indicates that seawater was well mixed at that time. Over the same interval, the seawater Mo-isotope composition, based upon well-preserved samples from Italy, was persistently atypical, with δ98/95Mo ranging between -0.7 and +0.7 permil [3]. All the samples analysed here accumulated under highly anoxic conditions and contain highly abundant

  2. Union Agency Lecture: Predicting and Managing Extreme Events

    Science.gov (United States)

    Lubchenco, J.

    2011-12-01

    From tsunamis to tornadoes to hurricanes, floods, droughts, and heat waves, 2011 has been a year of extreme events reminding us of the vulnerability of the nation's communities to such events and the need to enhance our ability to anticipate and mitigate impacts of extreme events. Among its many roles, NOAA is responsible for providing critical environmental intelligence to the nation. To deliver this intelligence, we observe, monitor, and forecast environmental changes, including extreme events. The different time horizons for different types of extreme events require different observing, analytical and modeling approaches. Short-fuse events such as tornadoes, heavy rainfall, and solar storms present different challenges from those whose development can be tracked: hurricanes, droughts, heat waves, extended flooding, hypoxia, or dispersion of volcanic ash, wildfire smoke or oil following a spill. Occurrence of compound or cascading events, such as heat, drought, and poor air quality, add complexity to our ability to predict. Recent extreme events not only challenge us to improve monitoring and forecasting abilities, but also to improve capabilities to deliver credible and actionable information widely. This talk discusses some of the larger scientific, technological, and social science challenges in predicting and reducing impacts from extreme events.

  3. General Resilience to Cope with Extreme Events

    OpenAIRE

    Brian Walker; Vincent, Jeffrey R.; Thomas Sterner; Jason Shogren; Marten Scheffer; Karl-Göran Mäler; Stephen Polasky; Kyle Meng; Geoffrey McCarney; Chuan-Zhong Li; Nils Kautsky; Hughes, Terry P.; Carl Folke; Gustav Engström; Anne-Sophie Crépin

    2012-01-01

    Resilience to specified kinds of disasters is an active area of research and practice. However, rare or unprecedented disturbances that are unusually intense or extensive require a more broad-spectrum type of resilience. General resilience is the capacity of social-ecological systems to adapt or transform in response to unfamiliar, unexpected and extreme shocks. Conditions that enable general resilience include diversity, modularity, openness, reserves, feedbacks, nestedness, monitoring, lead...

  4. Extreme events in multilayer, interdependent complex networks and control

    Science.gov (United States)

    Chen, Yu-Zhong; Huang, Zi-Gang; Zhang, Hai-Feng; Eisenberg, Daniel; Seager, Thomas P.; Lai, Ying-Cheng

    2015-11-01

    We investigate the emergence of extreme events in interdependent networks. We introduce an inter-layer traffic resource competing mechanism to account for the limited capacity associated with distinct network layers. A striking finding is that, when the number of network layers and/or the overlap among the layers are increased, extreme events can emerge in a cascading manner on a global scale. Asymptotically, there are two stable absorption states: a state free of extreme events and a state of full of extreme events, and the transition between them is abrupt. Our results indicate that internal interactions in the multiplex system can yield qualitatively distinct phenomena associated with extreme events that do not occur for independent network layers. An implication is that, e.g., public resource competitions among different service providers can lead to a higher resource requirement than naively expected. We derive an analytical theory to understand the emergence of global-scale extreme events based on the concept of effective betweenness. We also articulate a cost-effective control scheme through increasing the capacity of very few hubs to suppress the cascading process of extreme events so as to protect the entire multi-layer infrastructure against global-scale breakdown.

  5. Extreme meteorological events and nuclear facilities safety

    International Nuclear Information System (INIS)

    An External Event is an event that originates outside the site and whose effects on the Nuclear Power Plants (NPP) should be considered. Such events could be of natural or human induced origin and should be identified and selected for design purposes during the site evaluation process. This work shows that the subtropics and mid latitudes of South America east of the Andes Mountain Range have been recognized as prone to severe convective weather. In Brazil, the events of tornadoes are becoming frequent; however there is no institutionalized procedure for a systematic documentation of severe weather. The information is done only for some scientists and by the newspapers. Like strong wind can affect the structural integrity of buildings or the pressure differential can affect the ventilation system, our concern is the safety of NPP and for this purpose the recommendations of International Atomic Energy Agency, Nuclear Regulatory Commission and Comissao Nacional de Energia Nuclear are showed and also a data base of tornadoes in Brazil is done. (author)

  6. General Resilience to Cope with Extreme Events

    Directory of Open Access Journals (Sweden)

    Brian Walker

    2012-11-01

    Full Text Available Resilience to specified kinds of disasters is an active area of research and practice. However, rare or unprecedented disturbances that are unusually intense or extensive require a more broad-spectrum type of resilience. General resilience is the capacity of social-ecological systems to adapt or transform in response to unfamiliar, unexpected and extreme shocks. Conditions that enable general resilience include diversity, modularity, openness, reserves, feedbacks, nestedness, monitoring, leadership, and trust. Processes for building general resilience are an emerging and crucially important area of research.

  7. Estimating least-developed countries' vulnerability to climate-related extreme events over the next 50 years

    NARCIS (Netherlands)

    Patt, A.G.; Tadross, M.; Nussbaumer, P.; Asante, K.; Metzger, M.J.; Rafael, J.; Goujon, A.; Brundrit, G.

    2010-01-01

    When will least developed countries be most vulnerable to climate change, given the influence of projected socio-economic development? The question is important, not least because current levels of international assistance to support adaptation lag more than an order of magnitude below what analysts

  8. Crop Diversiifcation in Coping with Extreme Weather Events in China

    Institute of Scientific and Technical Information of China (English)

    HUANG Ji-kun; JIANG Jing; WANG Jin-xia; HOU Ling-ling

    2014-01-01

    Apart from the long-term effects of climate change, the frequency and severity of extreme weather events have been increasing. Given the risks posed by climate change, particularly the changes in extreme weather events, the question of how to adapt to these changes and mitigate their negative impacts has received great attention from policy makers. The overall goals of this study are to examine whether farmers adapt to extreme weather events through crop diversiifcation and which factors inlfuence farmers’ decisions on crop diversiifcation against extreme weather events in China. To limit the scope of this study, we focus on drought and lfood events only. Based on a unique large-scale household survey in nine provinces, this study ifnds that farmers respond to extreme weather events by increasing crop diversiifcation. Their decision to diversify crops is significantly influenced by their experiences of extreme weather events in the previous year. Such results are understandable because farmers’ behaviors are normally based on their expectations. Moreover, household characteristics also affect farmers’ decisions on crop diversiifcation strategy, and their effects differ by farmers’ age and gender. This paper concludes with several policy implications.

  9. Sovereign Default Analysis through Extreme Events Identification

    Directory of Open Access Journals (Sweden)

    Vasile George MARICA

    2015-06-01

    Full Text Available This paper investigates contagion in international credit markets through the use of a novel jump detection technique proposed by Chan and Maheuin (2002. This econometrical methodology is preferred because it is non-linear by definition and not a subject to volatility bias. Also, the identified jumps in CDS premiums are considered as outliers positioned beyond any stochastic movement that can and is already modelled through well-known linear analysis. Though contagion is hard to define, we show that extreme discrete movements in default probabilities inferred from CDS premiums can lead to sound economic conclusions about the risk profile of sovereign nations in international bond markets. We find evidence of investor sentiment clustering for countries with unstable political regimes or that are engaged in armed conflict. Countries that have in their recent history faced currency or financial crises are less vulnerable to external unexpected shocks. First we present a brief history of sovereign defaults with an emphasis on their increased frequency and geographical reach, as financial markets become more and more integrated. We then pass to a literature review of the most important definitions for contagion, and discuss what quantitative methods are available to detect the presence of contagion. The paper continues with the details for the methodology of jump detection through non-linear modelling and its use in the field of contagion identification. In the last sections we present the estimation results for simultaneous jumps between emerging markets CDS and draw conclusions on the difference of behavior in times of extreme movement versus tranquil periods.

  10. Impact of an extreme climatic event on community assembly

    Science.gov (United States)

    Thibault, Katherine M.; Brown, James H.

    2008-01-01

    Extreme climatic events are predicted to increase in frequency and magnitude, but their ecological impacts are poorly understood. Such events are large, infrequent, stochastic perturbations that can change the outcome of entrained ecological processes. Here we show how an extreme flood event affected a desert rodent community that has been monitored for 30 years. The flood (i) caused catastrophic, species-specific mortality; (ii) eliminated the incumbency advantage of previously dominant species; (iii) reset long-term population and community trends; (iv) interacted with competitive and metapopulation dynamics; and (v) resulted in rapid, wholesale reorganization of the community. This and a previous extreme rainfall event were punctuational perturbations—they caused large, rapid population- and community-level changes that were superimposed on a background of more gradual trends driven by climate and vegetation change. Captured by chance through long-term monitoring, the impacts of such large, infrequent events provide unique insights into the processes that structure ecological communities. PMID:18303115

  11. Predictability of extreme events in a branching diffusion model

    CERN Document Server

    Gabrielov, Andrei; Olsen, Sayaka; Zaliapin, Ilya

    2010-01-01

    We propose a framework for studying predictability of extreme events in complex systems. Major conceptual elements -- hierarchical structure, spatial dynamics, and external driving -- are combined in a classical branching diffusion with immigration. New elements -- observation space and observed events -- are introduced in order to formulate a prediction problem patterned after the geophysical and environmental applications. The problem consists of estimating the likelihood of occurrence of an extreme event given the observations of smaller events while the complete internal dynamics of the system is unknown. We look for premonitory patterns that emerge as an extreme event approaches; those patterns are deviations from the long-term system's averages. We have found a single control parameter that governs multiple spatio-temporal premonitory patterns. For that purpose, we derive i) complete analytic description of time- and space-dependent size distribution of particles generated by a single immigrant; ii) the...

  12. Measuring the effects of extreme weather events on yields

    Directory of Open Access Journals (Sweden)

    J.P. Powell

    2016-06-01

    Full Text Available Extreme weather events are expected to increase worldwide, therefore, anticipating and calculating their effects on crop yields is important for topics ranging from food security to the economic viability of biomass products. Given the local nature of weather, particularly precipitation, effects are best measured at a local level. This paper analyzes weather events at the level of the farm for a specific crop, winter wheat. Once it has been established that extreme events are expected to continue occurring at historically high levels for farming locations throughout the Netherlands, the effects of those events on wheat yields are estimated while controlling for the other major input factors affecting yields. Econometric techniques are applied to an unbalanced panel data set of 334 farms for a period of up to 12 years. Analyzes show that the number of days with extreme high temperatures in Dutch wheat growing regions has significantly increased since the early 1900s, while the number of extreme low temperature events has fallen over that same period. The effects of weather events on wheat yields were found to be time specific in that the week in which an event occurred determined its effect on yields. High temperature events and precipitation events were found to significantly decrease yields.

  13. Operational early warning platform for extreme meteorological events

    Science.gov (United States)

    Mühr, Bernhard; Kunz, Michael

    2015-04-01

    Operational early warning platform for extreme meteorological events Most natural disasters are related to extreme weather events (e.g. typhoons); weather conditions, however, are also highly relevant for humanitarian and disaster relief operations during and after other natural disaster like earthquakes. The internet service "Wettergefahren-Frühwarnung" (WF) provides various information on extreme weather events, especially when these events are associated with a high potential for large damage. The main focus of the platform is on Central Europe, but major events are also monitored worldwide on a daily routine. WF provides high-resolution forecast maps for many weather parameters which allow detailed and reliable predictions about weather conditions during the next days in the affected areas. The WF service became operational in February 2004 and is part of the Center for Disaster Management and Risk Reduction Technology (CEDIM) since 2007. At the end of 2011, CEDIM embarked a new type of interdisciplinary disaster research termed as forensic disaster analysis (FDA) in near real time. In case of an imminent extreme weather event WF plays an important role in CEDIM's FDA group. It provides early and precise information which are always available and updated several times during a day and gives advice and assists with articles and reports on extreme events.

  14. Extreme precipitation events and related weather patterns over Iraq

    Science.gov (United States)

    raheem Al-nassar, Ali; Sangrà, Pablo; Alarcón, Marta

    2016-04-01

    This study aims to investigate the extreme precipitation events and the associated weather phenomena in the Middle East and particularly in Iraq. For this purpose we used Baghdad daily precipitation records from the Iraqi Meteorological and Seismology Organization combined with ECMWF (ERA-Interim) reanalysis data for the period from January 2002 to December 2013. Extreme events were found statistically at the 90% percentile of the recorded precipitation, and were highly correlated with hydrological flooding in some cities of Iraq. We identified fifteen extreme precipitation events. The analysis of the corresponding weather patterns (500 hPa and 250 hPa geopotential and velocity field distribution) indicated that 5 events were related with cut off low causing the highest precipitation (180 mm), 3 events related with rex block (158 mm), 3 events related with jet streak occurrence (130 mm) and 4 events related with troughs (107 mm). . Five of these events caused flash floods and in particular one of them related with a rex block was the most dramatic heavy rain event in Iraq in 30 years. We investigated for each case the convective instability and dynamical forcing together with humidity sources. For convective instability we explored the distribution of the K index and SWEAT index. For dynamical forcing we analyzed at several levels Q vector, divergence, potential and relative vorticity advection and omega vertical velocity. Source of humidity was investigated through humidity and convergence of specific humidity distribution. One triggering factor of all the events is the advection and convergence of humidity from the Red Sea and the Persian Gulf. Therefore a necessary condition for extreme precipitation in Iraq is the advection and convergence of humidity from the Red Sea and Persian Gulf. Our preliminary analysis also indicates that extreme precipitation events are primary dynamical forced playing convective instability a secondary role.

  15. On the Probability of Occurrence of Extreme Space Weather Events

    Science.gov (United States)

    Riley, Pete

    2012-01-01

    By virtue of their rarity, extreme space weather events, such as the Carrington event of 1859, are difficult to study, their rates of occurrence are difficult to estimate, and prediction of a specific future event is virtually impossible. Additionally, events may be extreme relative to one parameter but normal relative to others. In this study, we analyze several measures of the severity of space weather events (flare intensity, coronal mass ejection speeds, Dst, and greater than 30 MeV proton fluences as inferred from nitrate records) to estimate the probability of occurrence of extreme events. By showing that the frequency of occurrence scales as an inverse power of the severity of the event, and assuming that this relationship holds at higher magnitudes, we are able to estimate the probability that an event larger than some criteria will occur within a certain interval of time in the future. For example, the probability of another Carrington event (based on Dst less than - 850 nT) occurring within the next decade is approximately 12%. We also identify and address several limitations with this approach. In particular, we assume time stationarity, and thus, the effects of long-term space climate change are not considered. While this technique cannot be used to predict specific events, it may ultimately be useful for probabilistic forecasting.

  16. Geophysical Hazards and Preventive Disaster Management of Extreme Natural Events

    Science.gov (United States)

    Ismail-Zadeh, A.; Takeuchi, K.

    2007-12-01

    Geophysical hazard is potentially damaging natural event and/or phenomenon, which may cause the loss of life or injury, property damage, social and economic disruption, or environmental degradation. Extreme natural hazards are a key manifestation of the complex hierarchical nonlinear Earth system. An understanding, accurate modeling and forecasting of the extreme hazards are most important scientific challenges. Several recent extreme natural events (e.g., 2004 Great Indian Ocean Earthquake and Tsunami and the 2005 violent Katrina hurricane) demonstrated strong coupling between solid Earth and ocean, and ocean and atmosphere. These events resulted in great humanitarian tragedies because of a weak preventive disaster management. The less often natural events occur (and the extreme events are rare by definition), the more often the disaster managers postpone the preparedness to the events. The tendency to reduce the funding for preventive disaster management of natural catastrophes is seldom follows the rules of responsible stewardship for future generations neither in developing countries nor in highly developed economies where it must be considered next to malfeasance. Protecting human life and property against earthquake disasters requires an uninterrupted chain of tasks: from (i) understanding of physics of the events, analysis and monitoring, through (ii) interpretation, modeling, hazard assessment, and prediction, to (iii) public awareness, preparedness, and preventive disaster management.

  17. Extreme events in gross primary production: a characterization across continents

    Directory of Open Access Journals (Sweden)

    J. Zscheischler

    2014-01-01

    Full Text Available Climate extremes can affect the functioning of terrestrial ecosystems, for instance via a reduction of the photosynthetic capacity or alterations of respiratory processes. Yet the dominant regional and seasonal effects of hydrometeorological extremes are still not well documented. Here we quantify and characterize the role of large spatiotemporal extreme events in gross primary production (GPP as triggers of continental anomalies. We also investigate seasonal dynamics of extreme impacts on continental GPP anomalies. We find that the 50 largest positive (increase in uptake and negative extremes (decrease in uptake on each continent can explain most of the continental variation in GPP, which is in line with previous results obtained at the global scale. We show that negative extremes are larger than positive ones and demonstrate that this asymmetry is particularly strong in South America and Europe. Most extremes in GPP start in early summer. Our analysis indicates that the overall impacts and the spatial extents of GPP extremes are power law distributed with exponents that vary little across continents. Moreover, we show that on all continents and for all data sets the spatial extents play a more important role than durations or maximal GPP anomaly when it comes to the overall impact of GPP extremes. An analysis of possible causes implies that across continents most extremes in GPP can best be explained by water scarcity rather than by extreme temperatures. However, for Europe, South America and Oceania we identify also fire as an important driver. Our findings are consistent with remote sensing products. An independent validation against a literature survey on specific extreme events supports our results to a large extent.

  18. Influence of Climate Change on Extreme Weather Events

    Science.gov (United States)

    Smith, R. L.; Wehner, M. F.

    2013-12-01

    The increasing frequency of extreme weather events raises the question of to what extent such events can be attributed to human causes. Within the climate literature, an approach has been developed based on a quantity known as the fraction of attributable risk, or FAR. The essence of this approach is to estimate the probability of the extreme event of interest from parallel runs of climate models under either anthropogenic or natural conditions; the two probabilities are then combined to produce the FAR. However, a number of existing approaches either make questionable assumptions about estimating extreme event probabilites (e.g. inappropriate assumption of the normal distribution) or ignore the differences between climate models and observational data. Here, we propose an approach based on extreme value theory, incorporated into a hierarchical model to account for differences among climate models. A related technique, based on the same modeling approach, leads to quantitative estimates of how the probability of an extreme event will change under future projected climate change. We illustrate the method with examples related to the European heatwave of 2003, the Russian heatwave of 2010, and the Texas/Oklahoma heatwave and drought of 2011.

  19. Extreme inflow events and synoptic forcing in Sydney catchments

    Energy Technology Data Exchange (ETDEWEB)

    Pepler, Acacia S; Rakich, Clinton S, E-mail: a.pepler@bom.gov.a [NSW Climate Services Section, Bureau of Meteorology PO Box 413, Darlinghurst, NSW 1300 (Australia)

    2010-08-15

    The Sydney catchment region encompasses over 16,000km{sup 2}, supplying water to over 4 million inhabitants. However, few studies have investigated the synoptic and climatic influences on inflow in this region, which are crucial for understanding the vulnerability of water supply in a changing climate. This study identifies extremely high and low inflow events between 1960 and 2008 based on catchment averages. The focus of the study is an analysis of the synoptic cause/s of each extreme inflow event. The events are evaluated to identify any trends and also to determine the concurrent significant climatic influences on rainfall over the catchments. Relationships between catchment inflow, rainfall, tropical SST indices, and other influencing factors such as observed wind and temperatures are investigated. Our results show that East Coast Lows and anomalously easterly flow are the drivers of high inflow events, with low inflow events dominated by westerly wind patterns and the El Nino-Southern Oscillation.

  20. Laws of small numbers extremes and rare events

    CERN Document Server

    Falk, Michael; Hüsler, Jürg

    2004-01-01

    Since the publication of the first edition of this seminar book in 1994, the theory and applications of extremes and rare events have enjoyed an enormous and still increasing interest. The intention of the book is to give a mathematically oriented development of the theory of rare events underlying various applications. This characteristic of the book was strengthened in the second edition by incorporating various new results on about 130 additional pages. Part II, which has been added in the second edition, discusses recent developments in multivariate extreme value theory. Particularly notable is a new spectral decomposition of multivariate distributions in univariate ones which makes multivariate questions more accessible in theory and practice. One of the most innovative and fruitful topics during the last decades was the introduction of generalized Pareto distributions in the univariate extreme value theory. Such a statistical modelling of extremes is now systematically developed in the multivariate fram...

  1. Characterization of extreme precipitation within atmospheric river events over California

    Science.gov (United States)

    Jeon, S.; Prabhat; Byna, S.; Gu, J.; Collins, W. D.; Wehner, M. F.

    2015-11-01

    Atmospheric rivers (ARs) are large, spatially coherent weather systems with high concentrations of elevated water vapor. These systems often cause severe downpours and flooding over the western coastal United States - and with the availability of more atmospheric moisture in the future under global warming we expect ARs to play an important role as potential causes of extreme precipitation changes. Therefore, we aim to investigate changes in extreme precipitation properties correlated with AR events in a warmer climate, which are large-scale meteorological patterns affecting the weather and climate of California. We have recently developed the TECA (Toolkit for Extreme Climate Analysis) software for automatically identifying and tracking features in climate data sets. Specifically, we can now identify ARs that make landfall on the western coast of North America. Based on this detection procedure, we can investigate the impact of ARs by exploring the spatial extent of AR precipitation using climate model (CMIP5) simulations and characterize spatial patterns of dependence for future projections between AR precipitation extremes under climate change within the statistical framework. Our results show that AR events in the future RCP (Representative Concentration Pathway)8.5 scenario (2076-2100) tend to produce heavier rainfall with higher frequency and longer days than events from the historical run (1981-2005). We also find that the dependence between extreme precipitation events has a shorter spatial range, within localized areas in California, under the high future emissions scenario than under the historical run.

  2. Extreme events and small-scale structure in computational turbulence

    Science.gov (United States)

    Zhai, X. M.; Yeung, P. K.; Sreenivasan, K. R.

    2015-11-01

    Detailed analyses have been made of data from a direct numerical simulation of turbulence on a periodic domain with 81923 grid points designed to improve our understanding of small-scale structure and intermittency. At the Reynolds number of this simulation (1300 based on the Taylor scale) extreme events of dissipation and enstrophy as large as 105 times the mean value are observed. These events are shown to possess a form that is different from similar events at low Reynolds numbers. Extreme vorticity appears to be ``chunky'' in character, in contrast to elongated vortex tubes at moderately large amplitudes commonly reported in the literature. We track the temporal evolution of these extreme events and find that they are generally short-lived, which suggests frequent sampling on-the-fly is useful. Extreme magnitudes of energy dissipation rate and enstrophy are essentially coincident in space and remain so during their evolution. Numerical tests show sensitivity to small-scale resolution and sampling but not machine precision. The connections expected between indicators of fine-scale intermittency such as acceleration statistics and the anomalous scaling of high-order velocity structure functions are also investigated. Supported by NSF Grant ACI-1036170 (Track 1 Petascale Resource Allocations Program).

  3. What is the right way to talk about extreme events?

    Science.gov (United States)

    Sobel, A. H.

    2013-12-01

    Extreme weather events draw the attention of the public. By demonstrating the vulnerability of human society to climate, extreme events can cause nonscientists -government leaders as well as the broader population - to take the danger posed by anthropogenic global warming more seriously than they otherwise might. An extreme event that draws media attention can become a 'teachable moment'. But extreme events are difficult to talk about in a way that honors both the strengths and weaknesses of the underlying science. No single event can be attributed to climate change, and some types of events are not even clearly influenced by it (or not in any ways our science can yet demonstrate). Strong, media-friendly statements that closely connect specific events to climate - designed to make best use of the moment's teachability - can easily overstate the case. This will raise the hackles of one's colleagues, at a minimum, and at worst, may damage the credibility of the field more broadly. Yet talking too much about the uncertainties runs the risk of understating the basic truth that global warming is real and dangerous, and may lend inadvertent support to anti-scientific denialism. I will discuss this tension in the context of my own experiences in the media after 'Superstorm' Sandy. I will address arguments I have heard, from social scientists and media consultants, to the effect that climate scientists should adopt communications strategies that lead to stronger, more media-friendly statements, and learn to suppress the tendency, bred into us during our scientific training, to emphasize the uncertainties.

  4. The Integrated periodogram of a dependent extremal event sequence

    DEFF Research Database (Denmark)

    Mikosch, Thomas Valentin; Zhao, Yuwei

    2015-01-01

    We investigate the asymptotic properties of the integrated periodogram calculated from a sequence of indicator functions of dependent extremal events. An event in Euclidean space is extreme if it occurs far away from the origin. We use a regular variation condition on the underlying stationary.......i.d. case a Brownian bridge appears. In the general case, we propose a stationary bootstrap procedure for approximating the distribution of the limiting process. The developed theory can be used to construct classical goodness-of-fit tests such as the Grenander–Rosenblatt and Cramér–von Mises tests which...... are based only on the extremes in the sample. We apply the test statistics to simulated and real-life data....

  5. Extreme Storm Event Assessments for Nuclear Facilities and Dam Safety

    Science.gov (United States)

    England, J. F.; Nicholson, T. J.; Prasad, R.

    2008-12-01

    Extreme storm events over the last 35 years are being assessed to evaluate flood estimates for safety assessments of dams, nuclear power plants, and other high-hazard structures in the U.S. The current storm rainfall design standard for evaluating the flood potential at dams and non-coastal nuclear power plants is the Probable Maximum Precipitation (PMP). PMP methods and estimates are published in the National Weather Service generalized hydrometeorological reports (HMRs). A new Federal Interagency cooperative effort is reviewing hydrometeorologic data from large storms which have occurred in the last 20 to 40 years and were not included in the database used in the development of many of the HMRs. Extreme storm data, such as the January 1996 storm in Pennsylvania, June 2008 Iowa storms, and Hurricanes Andrew (1992), Floyd (1999), Isabel (2003), Katrina (2005), need to be systematically assembled and analyzed for use in these regional extreme storm studies. Storm maximization, transposition, envelopment, and depth-area duration procedures will incorporate recent advances in hydrometeorology, including radar precipitation data and stochastic storm techniques. We describe new cooperative efforts to develop a database of extreme storms and to examine the potential impacts of recent extreme storms on PMP estimates. These efforts will be coordinated with Federal agencies, universities, and the private sector through an Extreme Storm Events Work Group under the Federal Subcommittee on Hydrology. This work group is chartered to coordinate studies and develop databases for reviewing and improving methodologies and data collection techniques used to estimate design precipitation up to and including the PMP. The initial effort focuses on collecting and reviewing extreme storm event data in the Southeastern U.S. that have occurred since Tropical Storm Agnes (1972). Uncertainties and exceedance probability estimates of PMP are being explored. Potential effects of climate

  6. Temporal Trends of Discrete Extreme Events - A Case Study

    Science.gov (United States)

    Rahmat, S. N.; Jayasuriya, N.; Bhuiyan, M.; Adnan, M. S.

    2016-07-01

    Investigating trends in discrete events is essential for the study of changing patterns of extreme events. Temporal trends in the inter-arrival times of occurrence of drought events were examined for 21 selected stations across Victoria, Australia. In the present study, the Standardize Precipitation Index (SPI) was applied for 12-month time scale to identify drought. A drought event here is defined as a period in which the SPI is continuously negative and reaching a value of -1.0 or less. Often, nonparametric tests are commonly used to test for trends including in discrete events. However, discrete events are not constant because of the presence of zero values or non-normality of data. The methodology applies to long-term records of event counts and is based on the stochastic concepts of Poisson process and standard linear regression. Overall, of the 21 stations, 15 showed statistically significant increasing frequency indicates those events are becoming more frequent. Only one station gave insignificant result. The remaining 5 stations showed the time between events was significantly increasing designates droughts are becoming less frequent.

  7. Investigation on rainfall extremes events trough a geoadditive model

    Science.gov (United States)

    Bocci, C.; Caporali, E.; Petrucci, A.; Rossi, G.

    2012-04-01

    Rainfall can be considered a very important variable, and rainfall extreme events analysis of great concern for the enormous impacts that they may have on everyday life particularly when related to intense rainfalls and floods, and hydraulic risk management. On the catchment area of Arno River in Tuscany, Central Italy, a geoadditive mixed model of rainfall extremes is developed. Most of the territory of Arno River has suffered in the past of many severe hydro-geological events, with high levels of risk due to the vulnerability of a unique artistic and cultural heritage. The area has a complex topography that greatly influences the precipitation regime. The dataset is composed by the time series of the annual maxima of daily rainfall recorded in about 400 rain gauges, spatially distributed over the catchment area of about 8.800 km2. The record period covers mainly the second half of 20th century. The rainfall observations are assumed to follow generalized extreme value distributions whose locations are spatially dependent and where the dependence is captured using a geoadditive model. In particular, since rainfall has a natural spatial domain and a significant spatial variability, a spatial hierarchical model for extremes is used. The spatial hierarchical models, in fact, take into account data from all locations, borrowing strength from neighbouring locations when they estimate parameters and are of great interest when small set of data is available, as in the case of rainfall extreme values. Together with rain gauges location variables further physiographic variables are investigated as explanation variables. The implemented geoadditive mixed model of spatially referenced time series of rainfall extreme values, is able to capture the spatial dynamics of the rainfall extreme phenomenon. Since the model shows evidence of a spatial trend in the rainfall extreme dynamic, the temporal dynamic and the time influence can be also taken into account. The implemented

  8. Analyzing Spatiotemporal Patterns of Extreme Precipitation Events in Southeastern Anatolia

    Science.gov (United States)

    Ozcan, O.; Bookhagen, B.; Musaoglu, N.

    2013-10-01

    Extreme environmental events, such as floods, droughts, rainstorms, and strong winds have severe consequences for human society. Changes in extreme weather and climate events have significant impacts and are among the most serious challenges to society in coping with a changing climate. The cost of damage caused by extreme climate events is rising all over the world. The European Environment Agency (EEA) report ("Climate Change, Impacts and Vulnerabilities in Europe 2012") stated that the cost of damage had increased from € 9 billion in the 1980s to € 13 billions in the 2000s. In the United States, the National Oceanic and Atmospheric Administration (NOAA) reported that 188 billion in damage was caused by the severe weather events in 2011 and 2012. Understanding and identifying hydrometeorologic extreme events and their changes through time are key in sustaining agriculture and socio-economic development. Planning for weather-related emergencies, agricultural and reservoir management and insurance risk calculations, all rely on knowledge of the frequency of these extreme events. The assessment of extreme precipitation is an important problem in hydrologic risk analysis and design. Erosion and removal of the fertile soil layer through hydroclimatic extreme events is also a serious problem in semi-arid to arid regions, especially in mediterranean climates. Accurate measurements of precipitation on a variety of space and time scales are important to climate scientists and decision makers, including hydrologists, agriculturalists and emergency managers. The historical record of precipitation observations is limited mostly to land areas where rain gauges can be deployed, and measurements from those instruments are sparse over large and meteorologically important regions of the Turkey, such as over the Southeastern Anatolia Region. While rain gauge measurements are often used to tune hydrologic models, they are limited by their spatial coverage. Remote sensing

  9. Temporal variation of extreme precipitation events in Lithuania

    Directory of Open Access Journals (Sweden)

    Egidijus Rimkus

    2011-05-01

    Full Text Available Heavy precipitation events in Lithuania for the period 1961-2008 were analysed. The spatial distribution and dynamics of precipitation extremes were investigated. Positive tendencies and in some cases statistically significant trends were determined for the whole of Lithuania. Atmospheric circulation processes were derived using Hess & Brezowski's classification of macrocirculation forms. More than one third of heavy precipitation events (37% were observed when the atmospheric circulation was zonal. The location of the central part of a cyclone (WZ weather condition subtype over Lithuania is the most common synoptic situation (27% during heavy precipitation events. Climatic projections according to outputs of the CCLM model are also presented in this research. The analysis shows that the recurrence of heavy precipitation events in the 21st century will increase significantly (by up to 22% in Lithuania.

  10. Tackling extremes: Challenges for ecological and evolutionary research on extreme climatic events.

    NARCIS (Netherlands)

    Bailey, Liam; Van de Pol, M.

    2016-01-01

    Summary Extreme climatic events (ECEs) are predicted to become more frequent as the climate changes. A rapidly increasing number of studies – though few on animals – suggest that the biological consequences of ECEs can be severe. However, ecological research on the impacts of ECEs has been limited b

  11. High resolution modelling of extreme precipitation events in urban areas

    Science.gov (United States)

    Siemerink, Martijn; Volp, Nicolette; Schuurmans, Wytze; Deckers, Dave

    2015-04-01

    The present day society needs to adjust to the effects of climate change. More extreme weather conditions are expected, which can lead to longer periods of drought, but also to more extreme precipitation events. Urban water systems are not designed for such extreme events. Most sewer systems are not able to drain the excessive storm water, causing urban flooding. This leads to high economic damage. In order to take appropriate measures against extreme urban storms, detailed knowledge about the behaviour of the urban water system above and below the streets is required. To investigate the behaviour of urban water systems during extreme precipitation events new assessment tools are necessary. These tools should provide a detailed and integral description of the flow in the full domain of overland runoff, sewer flow, surface water flow and groundwater flow. We developed a new assessment tool, called 3Di, which provides detailed insight in the urban water system. This tool is based on a new numerical methodology that can accurately deal with the interaction between overland runoff, sewer flow and surface water flow. A one-dimensional model for the sewer system and open channel flow is fully coupled to a two-dimensional depth-averaged model that simulates the overland flow. The tool uses a subgrid-based approach in order to take high resolution information of the sewer system and of the terrain into account [1, 2]. The combination of using the high resolution information and the subgrid based approach results in an accurate and efficient modelling tool. It is now possible to simulate entire urban water systems using extreme high resolution (0.5m x 0.5m) terrain data in combination with a detailed sewer and surface water network representation. The new tool has been tested in several Dutch cities, such as Rotterdam, Amsterdam and The Hague. We will present the results of an extreme precipitation event in the city of Schiedam (The Netherlands). This city deals with

  12. Possible future changes in extreme events over Northern Eurasia

    Science.gov (United States)

    Monier, Erwan; Sokolov, Andrei; Scott, Jeffery

    2013-04-01

    In this study, we investigate possible future climate change over Northern Eurasia and its impact on extreme events. Northern Eurasia is a major player in the global carbon budget because of boreal forests and peatlands. Circumpolar boreal forests alone contain more than five times the amount of carbon of temperate forests and almost double the amount of carbon of the world's tropical forests. Furthermore, severe permafrost degradation associated with climate change could result in peatlands releasing large amounts of carbon dioxide and methane. Meanwhile, changes in the frequency and magnitude of extreme events, such as extreme precipitation, heat waves or frost days are likely to have substantial impacts on Northern Eurasia ecosystems. For this reason, it is very important to quantify the possible climate change over Northern Eurasia under different emissions scenarios, while accounting for the uncertainty in the climate response and changes in extreme events. For several decades, the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change has been investigating uncertainty in climate change using the MIT Integrated Global System Model (IGSM) framework, an integrated assessment model that couples an earth system model of intermediate complexity (with a 2D zonal-mean atmosphere) to a human activity model. In this study, regional change is investigated using the MIT IGSM-CAM framework that links the IGSM to the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). New modules were developed and implemented in CAM to allow climate parameters to be changed to match those of the IGSM. The simulations presented in this paper were carried out for two emission scenarios, a "business as usual" scenario and a 660 ppm of CO2-equivalent stabilization, which are similar to, respectively, the Representative Concentration Pathways RCP8.5 and RCP4.5 scenarios. Values of climate sensitivity and net aerosol

  13. Extreme sea-level events in coastal regions

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    that the outcome of the project has been a code that is capable of predicting correct trends more often (15 out of 20) than the other ‘black box’ codes in operation at various agencies. U. N. SINHA CSIR-Centre for Mathematical Modelling and Computer... of the extreme climate events. Their past trends, future projections and vulnerabi- lity and adaptation to such events are discussed in the report. The report was based on the efforts of both the working groups of the IPCC, WG I, which deals with the science...

  14. Expected impacts of climate change on extreme climate events

    International Nuclear Information System (INIS)

    An overview of the expected change of climate extremes during this century due to greenhouse gases and aerosol anthropogenic emissions is presented. The most commonly used methodologies rely on the dynamical or statistical down-scaling of climate projections, performed with coupled atmosphere-ocean general circulation models. Either of dynamical or of statistical type, down-scaling methods present strengths and weaknesses, but neither their validation on present climate conditions, nor their potential ability to project the impact of climate change on extreme event statistics allows one to give a specific advantage to one of the two types. The results synthesized in the last IPCC report and more recent studies underline a convergence for a very likely increase in heat wave episodes over land surfaces, linked to the mean warming and the increase in temperature variability. In addition, the number of days of frost should decrease and the growing season length should increase. The projected increase in heavy precipitation events appears also as very likely over most areas and also seems linked to a change in the shape of the precipitation intensity distribution. The global trends for drought duration are less consistent between models and down-scaling methodologies, due to their regional variability. The change of wind-related extremes is also regionally dependent, and associated to a poleward displacement of the mid-latitude storm tracks. The specific study of extreme events over France reveals the high sensitivity of some statistics of climate extremes at the decadal time scale as a consequence of regional climate internal variability. (authors)

  15. Extreme Events and Energy Providers: Science and Innovation

    Science.gov (United States)

    Yiou, P.; Vautard, R.

    2012-04-01

    Most socio-economic regulations related to the resilience to climate extremes, from infrastructure or network design to insurance premiums, are based on a present-day climate with an assumption of stationarity. Climate extremes (heat waves, cold spells, droughts, storms and wind stilling) affect in particular energy production, supply, demand and security in several ways. While national, European or international projects have generated vast amounts of climate projections for the 21st century, their practical use in long-term planning remains limited. Estimating probabilistic diagnostics of energy user relevant variables from those multi-model projections will help the energy sector to elaborate medium to long-term plans, and will allow the assessment of climate risks associated to those plans. The project "Extreme Events for Energy Providers" (E3P) aims at filling a gap between climate science and its practical use in the energy sector and creating in turn favourable conditions for new business opportunities. The value chain ranges from addressing research questions directly related to energy-significant climate extremes to providing innovative tools of information and decision making (including methodologies, best practices and software) and climate science training for the energy sector, with a focus on extreme events. Those tools will integrate the scientific knowledge that is developed by scientific communities, and translate it into a usable probabilistic framework. The project will deliver projection tools assessing the probabilities of future energy-relevant climate extremes at a range of spatial scales varying from pan-European to local scales. The E3P project is funded by the Knowledge and Innovation Community (KIC Climate). We will present the mechanisms of interactions between academic partners, SMEs and industrial partners for this project. Those mechanisms are elementary bricks of a climate service.

  16. Extreme event statistics of daily rainfall: dynamical systems approach

    Science.gov (United States)

    Cigdem Yalcin, G.; Rabassa, Pau; Beck, Christian

    2016-04-01

    We analyse the probability densities of daily rainfall amounts at a variety of locations on Earth. The observed distributions of the amount of rainfall fit well to a q-exponential distribution with exponent q close to q≈ 1.3. We discuss possible reasons for the emergence of this power law. In contrast, the waiting time distribution between rainy days is observed to follow a near-exponential distribution. A careful investigation shows that a q-exponential with q≈ 1.05 yields the best fit of the data. A Poisson process where the rate fluctuates slightly in a superstatistical way is discussed as a possible model for this. We discuss the extreme value statistics for extreme daily rainfall, which can potentially lead to flooding. This is described by Fréchet distributions as the corresponding distributions of the amount of daily rainfall decay with a power law. Looking at extreme event statistics of waiting times between rainy days (leading to droughts for very long dry periods) we obtain from the observed near-exponential decay of waiting times extreme event statistics close to Gumbel distributions. We discuss superstatistical dynamical systems as simple models in this context.

  17. Extreme Events and Sea Waves along Italian Coasts

    Science.gov (United States)

    Morucci, Sara; Nardone, Gabriele; Picone, Marco

    2014-05-01

    The Italian Wind Waves Measurement Network (RON) is composed by 15 directional buoys uniformly distributed all around the Italian coasts and provides data since 1989. Data, collected on these 15 locations represent one of the most accurate and complete oceanographic database in the Central Mediterranean Sea for many environmental issues such as studies on climate changes and variability and assessment of marine environments. In this framework the study on wind waves extreme events and storm surges is here presented. The first step in the extreme events analysis consists in extracting a set of independent wave events using different methodologies, such as Peak Over Threshold and annual maxima methods. Attention has been focused on the determination of the historical storms in terms of the return times and the expected values of the wave heights over several decades. For this purpose an investigation on several statistical distribution has been carried out for each measurement station. As well known there are many distribution function candidates for extreme wave analysis. In this study, extreme events analysis has been made through the GPD (and GEV) that provides different kind of distributions such as Gumbel, Frechet and Weibull, depending on the values of the estimated parameters. These distributions have been used in order to evaluate the wave height return level and return times up to 50 years. Even though the series are 25 years long, the analysis gives valuable information about the spatial distribution of the storms and their variability on a decadal time scale in the Central Mediterranean Sea. For each time series, a set of statistical parameters has been evaluated, such as the average number of storms per year, the return period corresponding to the maximum value of observed Hs, the return level corresponding to a period of 20 to 50 years depending on the availability of data. Finally, storm surge events have been considered highlighting the correlation

  18. Distributing urban resilience to extreme precipitation events with green infrastructure

    Science.gov (United States)

    Montalto, F. A.; Catalano De Sousa, M.; Yu, Z.

    2013-12-01

    New urban green spaces are being designed to manage stormwater, but their performance in a changing climate is untested. Key questions pertain to the ability of these systems to mitigate flood and sewer overflow concerns during impact of extreme events on, and to withstand (biologically and physically) increased frequency and intensity of drought and flood conditions. In this presentation, we present field data characterizing performance of a bioretention area, a stormwater treatment wetland, and a green roof under Hurricane Irene (2011), Superstorm Sandy (2012), and a variety of extreme precipitation events during the summer of 2013. Specifically, we characterize the fate and volume of incident runon and/or precipitation to the facilities during these extreme events, and compare them to long term monitored performance metrics. We also present laboratory test results documenting how vegetation in these facilities stands up to simulated flood and drought conditions. The results are discussed in the context of predicted climate change, specifically associated with the amount and timing of precipitation.

  19. Extreme Rainfall Events Over Southern Africa: Assessment of a Climate Model to Reproduce Daily Extremes

    Science.gov (United States)

    Williams, C.; Kniveton, D.; Layberry, R.

    2007-12-01

    It is increasingly accepted that any possible climate change will not only have an influence on mean climate but may also significantly alter climatic variability. This issue is of particular importance for environmentally vulnerable regions such as southern Africa. The subcontinent is considered especially vulnerable extreme events, due to a number of factors including extensive poverty, disease and political instability. Rainfall variability and the identification of rainfall extremes is a function of scale, so high spatial and temporal resolution data are preferred to identify extreme events and accurately predict future variability. The majority of previous climate model verification studies have compared model output with observational data at monthly timescales. In this research, the assessment of a state-of-the-art climate model to simulate climate at daily timescales is carried out using satellite derived rainfall data from the Microwave Infra-Red Algorithm (MIRA). This dataset covers the period from 1993-2002 and the whole of southern Africa at a spatial resolution of 0.1 degree longitude/latitude. Once the model's ability to reproduce extremes has been assessed, idealised regions of SST anomalies are used to force the model, with the overall aim of investigating the ways in which SST anomalies influence rainfall extremes over southern Africa. In this paper, results from sensitivity testing of the UK Meteorological Office Hadley Centre's climate model's domain size are firstly presented. Then simulations of current climate from the model, operating in both regional and global mode, are compared to the MIRA dataset at daily timescales. Thirdly, the ability of the model to reproduce daily rainfall extremes will be assessed, again by a comparison with extremes from the MIRA dataset. Finally, the results from the idealised SST experiments are briefly presented, suggesting associations between rainfall extremes and both local and remote SST anomalies.

  20. Impacts of extreme weather events on transport infrastructure in Norway

    Science.gov (United States)

    Frauenfelder, Regula; Solheim, Anders; Isaksen, Ketil; Romstad, Bård; Dyrrdal, Anita V.; Ekseth, Kristine H. H.; Gangstø Skaland, Reidun; Harbitz, Alf; Harbitz, Carl B.; Haugen, Jan E.; Hygen, Hans O.; Haakenstad, Hilde; Jaedicke, Christian; Jónsson, Árni; Klæboe, Ronny; Ludvigsen, Johanna; Meyer, Nele K.; Rauken, Trude; Sverdrup-Thygeson, Kjetil

    2016-04-01

    With the latest results on expected future increase in air temperature and precipitation changes reported by the Intergovernmental Panel on Climate Change (IPCC), the climate robustness of important infrastructure is of raising concern in Norway, as well as in the rest of Europe. Economic consequences of natural disasters have increased considerably since 1950. In addition to the effect of demographic changes such as population growth, urbanization and more and more concentration of valuable assets, this increase is also related to an augmenting frequency of extreme events, such as storms, flooding, drought, and landslides. This change is also observable in Norway, where the increased frequency of strong precipitation has led to frequent flooding and landslide events during the last 20 years. A number of studies show that climate change causes an increase in both frequency and intensity of several types of extreme weather, especially when it comes to precipitation. Such extreme weather events greatly affect the transport infrastructure, with numerous and long closures of roads and railroads, in addition to damage and repair costs. Frequent closures of railroad and roads lead to delay or failure in delivery of goods, which again may lead to a loss of customers and/or - eventually - markets. Much of the Norwegian transport infrastructure is more than 50 years old and therefore not adequately dimensioned, even for present climatic conditions. In order to assess these problems and challenges posed to the Norwegian transport infrastructure from present-day and future extreme weather events, the project "Impacts of extreme weather events on infrastructure in Norway (InfraRisk)" was performed under the research Council of Norway program 'NORKLIMA', between 2009 and 2013. The main results of the project are: - Moderate to strong precipitation events have become more frequent and more intense in Norway over the last 50 years, and this trend continues throughout the 21st

  1. Financial market response to extreme events indicating climatic change

    Science.gov (United States)

    Anttila-Hughes, J. K.

    2016-05-01

    A variety of recent extreme climatic events are considered to be strong evidence that the climate is warming, but these incremental advances in certainty often seem ignored by non-scientists. I identify two unusual types of events that are considered to be evidence of climate change, announcements by NASA that the global annual average temperature has set a new record, and the sudden collapse of major polar ice shelves, and then conduct an event study to test whether news of these events changes investors' valuation of energy companies, a subset of firms whose future performance is closely tied to climate change. I find evidence that both classes of events have influenced energy stock prices since the 1990s, with record temperature announcements on average associated with negative returns and ice shelf collapses associated with positive returns. I identify a variety of plausible mechanisms that may be driving these differential responses, discuss implications for energy markets' views on long-term regulatory risk, and conclude that investors not only pay attention to scientifically significant climate events, but discriminate between signals carrying different information about the nature of climatic change.

  2. Extreme Drought Events Revealed in Amazon Tree Ring Records

    Science.gov (United States)

    Jenkins, H. S.; Baker, P. A.; Guilderson, T. P.

    2010-12-01

    The Amazon basin is a center of deep atmospheric convection and thus acts as a major engine for global hydrologic circulation. Yet despite its significance, a full understanding of Amazon rainfall variability remains elusive due to a poor historical record of climate. Temperate tree rings have been used extensively to reconstruct climate over the last thousand years, however less attention has been given to the application of dendrochronology in tropical regions, in large part due to a lower frequency of tree species known to produce annual rings. Here we present a tree ring record of drought extremes from the Madre de Dios region of southeastern Peru over the last 190 years. We confirm that tree ring growth in species Cedrela odorata is annual and show it to be well correlated with wet season precipitation. This correlation is used to identify extreme dry (and wet) events that have occurred in the past. We focus on drought events identified in the record as drought frequency is expected to increase over the Amazon in a warming climate. The Cedrela chronology records historic Amazon droughts of the 20th century previously identified in the literature and extends the record of drought for this region to the year 1816. Our analysis shows that there has been an increase in the frequency of extreme drought (mean recurrence interval = 5-6 years) since the turn of the 20th century and both Atlantic and Pacific sea surface temperature (SST) forcing mechanisms are implicated.

  3. Extreme events in total ozone over Arosa – Part 1: Application of extreme value theory

    Directory of Open Access Journals (Sweden)

    H. E. Rieder

    2010-10-01

    Full Text Available In this study ideas from extreme value theory are for the first time applied in the field of stratospheric ozone research, because statistical analysis showed that previously used concepts assuming a Gaussian distribution (e.g. fixed deviations from mean values of total ozone data do not adequately address the structure of the extremes. We show that statistical extreme value methods are appropriate to identify ozone extremes and to describe the tails of the Arosa (Switzerland total ozone time series. In order to accommodate the seasonal cycle in total ozone, a daily moving threshold was determined and used, with tools from extreme value theory, to analyse the frequency of days with extreme low (termed ELOs and high (termed EHOs total ozone at Arosa. The analysis shows that the Generalized Pareto Distribution (GPD provides an appropriate model for the frequency distribution of total ozone above or below a mathematically well-defined threshold, thus providing a statistical description of ELOs and EHOs. The results show an increase in ELOs and a decrease in EHOs during the last decades. The fitted model represents the tails of the total ozone data set with high accuracy over the entire range (including absolute monthly minima and maxima, and enables a precise computation of the frequency distribution of ozone mini-holes (using constant thresholds. Analyzing the tails instead of a small fraction of days below constant thresholds provides deeper insight into the time series properties. Fingerprints of dynamical (e.g. ENSO, NAO and chemical features (e.g. strong polar vortex ozone loss, and major volcanic eruptions, can be identified in the observed frequency of extreme events throughout the time series. Overall the new approach to analysis of extremes provides more information on time series properties and variability than previous approaches that use only monthly averages and/or mini-holes and mini-highs.

  4. Clustering of extreme events created by multiple correlated maxima

    Science.gov (United States)

    Azevedo, Davide; Freitas, Ana Cristina Moreira; Freitas, Jorge Milhazes; Rodrigues, Fagner B.

    2016-02-01

    We consider stochastic processes arising from dynamical systems by evaluating an observable function along the orbits of the system. The novelty is that we will consider observables achieving a global maximum value (possible infinite) at multiple points with special emphasis for the case where these maximal points are correlated or bound by belonging to the same orbit of a certain chosen point. These multiple correlated maxima can be seen as a new mechanism creating clustering of extreme observations, i.e., the occurrence of several extreme observations concentrated in the time frame. We recall that clustering was intimately connected with periodicity when the maximum was achieved at a single point. We will study this mechanism for creating clustering and will address the existence of limiting Extreme Value Laws, the repercussions on the value of the Extremal Index, the impact on the limit of Rare Events Points Processes, the influence on clustering patterns and the competition of domains of attraction. We also consider briefly and for comparison purposes multiple uncorrelated maxima. The systems considered include expanding maps of the interval such as Rychlik maps but also maps with an indifferent fixed point such as Manneville-Pomeau maps.

  5. Bayesian analysis for extreme climatic events: A review

    Science.gov (United States)

    Chu, Pao-Shin; Zhao, Xin

    2011-11-01

    This article reviews Bayesian analysis methods applied to extreme climatic data. We particularly focus on applications to three different problems related to extreme climatic events including detection of abrupt regime shifts, clustering tropical cyclone tracks, and statistical forecasting for seasonal tropical cyclone activity. For identifying potential change points in an extreme event count series, a hierarchical Bayesian framework involving three layers - data, parameter, and hypothesis - is formulated to demonstrate the posterior probability of the shifts throughout the time. For the data layer, a Poisson process with a gamma distributed rate is presumed. For the hypothesis layer, multiple candidate hypotheses with different change-points are considered. To calculate the posterior probability for each hypothesis and its associated parameters we developed an exact analytical formula, a Markov Chain Monte Carlo (MCMC) algorithm, and a more sophisticated reversible jump Markov Chain Monte Carlo (RJMCMC) algorithm. The algorithms are applied to several rare event series: the annual tropical cyclone or typhoon counts over the central, eastern, and western North Pacific; the annual extremely heavy rainfall event counts at Manoa, Hawaii; and the annual heat wave frequency in France. Using an Expectation-Maximization (EM) algorithm, a Bayesian clustering method built on a mixture Gaussian model is applied to objectively classify historical, spaghetti-like tropical cyclone tracks (1945-2007) over the western North Pacific and the South China Sea into eight distinct track types. A regression based approach to forecasting seasonal tropical cyclone frequency in a region is developed. Specifically, by adopting large-scale environmental conditions prior to the tropical cyclone season, a Poisson regression model is built for predicting seasonal tropical cyclone counts, and a probit regression model is alternatively developed toward a binary classification problem. With a non

  6. On the influence of wind on extreme wave events

    Directory of Open Access Journals (Sweden)

    J. Touboul

    2007-01-01

    Full Text Available This work studies the impact of wind on extreme wave events, by means of numerical analysis. A High Order Spectral Method (HOSM is used to generate freak, or rogue waves, on the basis of modulational instability. Wave fields considered here are chosen to be unstable to two kinds of perturbations. The evolution of components during the propagation of the wave fields is presented. Their evolution under the action of wind, modeled through Jeffreys' sheltering mechanism, is investigated and compared to the results without wind. It is found that wind sustains rogue waves. The perturbation most influenced by wind is not necessarily the most unstable.

  7. Simulating an Extreme Wind Event in a Topographically Complex Region

    Science.gov (United States)

    Lennard, Christopher

    2014-07-01

    Complex topography modifies local weather characteristics such as air temperature, rainfall and airflow within a larger regional extent. The Cape Peninsula around Cape Town, South Africa, is a complex topographical feature responsible for the modification of rainfall and wind fields largely downstream of the Peninsula. During the passage of a cold front on 2 October 2002, an extreme wind event associated with tornado-like damage occurred in the suburb of Manenberg, however synoptic conditions did not indicate convective activity typically associated with a tornado. A numerical regional climate model was operated at very high horizontal resolution (500 m) to investigate the dynamics of the event. The model simulated an interaction between the topography of the peninsula and an airflow direction change associated with the passage of the cold front. A small region of cyclonic circulation was simulated over Manenberg that was embedded in an area of negative vorticity and a leeward gravity wave. The feature lasted 14 min and moved in a north to south direction. Vertically, it was not evident above 220 m. The model assessment describes this event as a shallow but intense cyclonic vortex generated in the lee of the peninsula through an interaction between the peninsula and a change in wind direction as the cold front made landfall. The model did not simulate wind speeds associated with the observed damage suggesting that the horizontal grid resolution ought to be at the scale of the event to more completely understand such microscale airflow phenomena.

  8. The 1859 space weather event revisited: limits of extreme activity

    Directory of Open Access Journals (Sweden)

    Cliver Edward W.

    2013-10-01

    Full Text Available The solar flare on 1 September 1859 and its associated geomagnetic storm remain the standard for an extreme solar-terrestrial event. The most recent estimates of the flare soft X-ray (SXR peak intensity and Dst magnetic storm index for this event are: SXR class = X45 (±5 (vs. X35 (±5 for the 4 November 2003 flare and minimum Dst = −900 (+50, −150 nT (vs. −825 to −900 nT for the great storm of May 1921. We have no direct evidence of an associated solar energetic proton (SEP event but a correlation between >30 MeV SEP fluence (F30 and flare size based on modern data yields a best guess F30 value of ~1.1 × 1010 pr cm−2 (with the ±1σ uncertainty spanning a range from ~109–1011 pr cm−2 for a composite (multi-flare plus shock 1859 event. This value is approximately twice that of estimates/measurements – ranging from ~5–7 × 109 pr cm−2 – for the largest SEP episodes (July 1959, November 1960, August 1972 in the modern era.

  9. Recent Changes of Some Observed Climate Extreme Events in Kano

    Directory of Open Access Journals (Sweden)

    Imole Ezekiel Gbode

    2015-01-01

    Full Text Available Observed rainfall and temperature data for the period 1960–2007 were used to examine recent changes of extreme climate over Kano, located in the Sahelian region of Nigeria. The RClimDex software package was employed to generate nine important climate indices as defined by the Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI. For the entire period, the results show a warming trend, an increased number of cool nights, more warm days, and a strong increase in the number of warm spells. The rainfall indices show a slight increase in annual total rainfall, a decrease in the maximum number of consecutive wet days, and a significant increase in the number of extremely wet days. Such changes in climate may result in an increasing demand for domestic energy for cooling and a higher evaporation rate from water bodies and irrigated crop. These findings may give some guidance to politicians and planners in how to best cope with these extreme weather and climate events.

  10. Top-side ionosphere response to extreme solar events

    Directory of Open Access Journals (Sweden)

    A. V. Dmitriev

    2006-07-01

    Full Text Available Strong X-flares and solar energetic particle (SEP fluxes are considered as sources of topside ionospheric disturbances observed by the ROCSAT-1/IPEI instrument during the Bastille Day event on 14 July 2000 and the Halloween event on 28 October–4 November 2003. It was found that within a prestorm period in the dayside ionosphere at altitudes of ~600 km the ion density increased up to ~80% in response to flare-associated enhancements of the solar X-ray emission. Ionospheric response to the SEP events was revealed both at sunlit and nightside hemispheres, where the ion density increased up to ~40% and 100%, respectively. We did not find any prominent response of the ion temperature to the X-ray and SEP enhancements. The largest X-ray and SEP impacts were found for the X17 solar flare on 28 October 2003, which was characterized by the most intense fluxes of solar EUV (Tsurutani et al., 2005 and relativistic solar particles (Veselovsky et al., 2004. Solar events on 14 July 2000 and 29 October 2003 demonstrate weaker impacts with respect to their X-ray and SEP intensities. The weakest ionospheric response is observed for the limb X28 solar flare on 4 November 2003. The topside ionosphere response to the extreme solar events is interpreted in terms of the short-duration impact of the solar electromagnetic radiation and the long-lasting impact of the SEP.

  11. Modern sedimentation and extreme event in the South China Sea

    Science.gov (United States)

    Chen, Yu-Huang; Su, Chih-Chieh

    2016-04-01

    The South China Sea is the largest marginal sea of the northwest Pacific. It is situated at the plate boundary of the Eurasian, Philippine Sea, and Indian plates and also on the North Western Pacific corridor of typhoons. The unique tectonic and climatic environment makes it has to face the potential of seafloor destructions, like submarine landslides and slumps, and high sediment discharges which induced by typhoon from Philippine. In this study, we analysis the sediment properties of modern extreme event records in cores and attempt to evaluate the history of extreme events in the South China Sea. Twelve gravity cores were collected in the central South China Sea basin and around Taiping island by using R/V Ocean Research 1 from 2014 to 2015 and a series of analysis including multi-sensor core logger, XRF core scanner (Itrax), core surface images, X-radiographs, bulk density, grain size, Pb-210 chronology and X-ray diffractometer were conducted in this study. On core surface images, an obvious brownish oxidized layer exist in core top with higher Pb-210 activity beneath this oxidized layer, and we speculate this layer is caused by nature hazard. According to the sampling time, we conjecture the oxidized layer might formed by typhoon Haiyan in 2013. In addition, the Itrax data shows high manganese content only exist in this layer which might related to the modern industrial pollution delivered by typhoon induced flooding from Philippine. The sedimentation rate of the non-event years in these cores which derived from Pb-210 chronology method is about 0.02 ~0.03 cm/yr. On contrary, the event layer caused by Haiyan with a recorded maximum 87cm deposits in the South China Sea. This study aims to characterize the typhoon induced deposits in the turbidite layer and use it to identify whether the other event layers recorded in these cores were related to typhoon activities and to reconstruct the strong tropical cyclone history in the western Pacific.

  12. Coastal evacuations by fish during extreme weather events

    Science.gov (United States)

    Bailey, Helen; Secor, David H.

    2016-01-01

    An increase in the intensity and frequency of extreme events is predicted to occur as a result of climate change. In coastal ecosystems, hurricanes and flooding can cause dramatic changes in water quality resulting in large mortality events in estuarine fauna. Facultative migration behaviors represent a key adaptation by which animals can evacuate ecological catastrophes, but remain poorly studied in marine systems. Here we identify coastal evacuations by otherwise resident riverine striped bass in the Hudson River Estuary, New York, USA, caused by an intense period of tropical storms in autumn 2011. These storms produced record rainfall and high water discharges into the Hudson River Estuary that increased the water level and reduced the water temperature, salinity and dissolved oxygen levels. Striped bass moved out of the estuary, exhibiting novel migration behaviours, that may have been in response to the strong flow and unsuitable conditions. In the months following the storms, some fish demonstrated exploratory trips back to the estuary, which may have been to assess the conditions before returning for the remainder of the winter. Behavioural adaptions to weather events by striped bass and other coastal fishes will depend on maintenance of key population segments and unimpeded evacuation routes. PMID:27455872

  13. Coastal evacuations by fish during extreme weather events.

    Science.gov (United States)

    Bailey, Helen; Secor, David H

    2016-01-01

    An increase in the intensity and frequency of extreme events is predicted to occur as a result of climate change. In coastal ecosystems, hurricanes and flooding can cause dramatic changes in water quality resulting in large mortality events in estuarine fauna. Facultative migration behaviors represent a key adaptation by which animals can evacuate ecological catastrophes, but remain poorly studied in marine systems. Here we identify coastal evacuations by otherwise resident riverine striped bass in the Hudson River Estuary, New York, USA, caused by an intense period of tropical storms in autumn 2011. These storms produced record rainfall and high water discharges into the Hudson River Estuary that increased the water level and reduced the water temperature, salinity and dissolved oxygen levels. Striped bass moved out of the estuary, exhibiting novel migration behaviours, that may have been in response to the strong flow and unsuitable conditions. In the months following the storms, some fish demonstrated exploratory trips back to the estuary, which may have been to assess the conditions before returning for the remainder of the winter. Behavioural adaptions to weather events by striped bass and other coastal fishes will depend on maintenance of key population segments and unimpeded evacuation routes. PMID:27455872

  14. Remote Sensing of Surficial Process Responses to Extreme Meteorological Events

    Science.gov (United States)

    Brakenridge, G. Robert

    1997-01-01

    Changes in the frequency and magnitude of extreme meteorological events are associated with changing environmental means. Such events are important in human affairs, and can also be investigated by orbital remote sensing. During the course of this project, we applied ERS-1, ERS-2, Radarsat, and an airborne sensor (AIRSAR-TOPSAR) to measure flood extents, flood water surface profiles, and flood depths. We established a World Wide Web site (the Dartmouth Flood Observatory) for publishing remote sensing-based maps of contemporary floods worldwide; this is also an online "active archive" that presently constitutes the only global compilation of extreme flood events. We prepared an article for EOS concerning SAR imaging of the Mississippi Valley flood; an article for the International Journal of Remote Sensing on measurement of a river flood wave using ERS-2, began work on an article (since completed and published) on the Flood Observatory for a Geoscience Information Society Proceedings volume, and presented lectures at several Geol. Soc. of America Natl. Meetings, an Assoc. of Amer. Geographers Natl. Meeting, and a Binghamton Geomorphology Symposium (all on SAR remote sensing of the Mississippi Valley flood). We expanded in-house modeling capabilities by installing the latest version of the Army Corps of Engineers RMA two-dimensional hydraulics software and BYU Engineering Graphics Lab's Surface Water Modeling System (finite elements based pre- and post-processors for RMA work) and also added watershed modeling software. We are presently comparing the results of the 2-d flow models with SAR image data. The grant also supported several important upgrades of pc-based remote sensing infrastructure at Dartmouth. During work on this grant, we collaborated with several workers at the U.S. Army Corps of Engineers, Remote Sensing/GIS laboratory (for flood inundation mapping and modeling; particularly of the Illinois River using the AIRSAR/TOPSAR/ERS-2 combined data), with Dr

  15. Crop insurance evaluation in response to extreme events

    Science.gov (United States)

    Moriondo, Marco; Ferrise, Roberto; Bindi, Marco

    2013-04-01

    Crop yield insurance has been indicated as a tool to manage the uncertainties of crop yields (Sherrick et al., 2004) but the changes in crop yield variability as expected in the near future should be carefully considered for a better quantitative assessment of farmer's revenue risk and insurance values in a climatic change regime (Moriondo et al., 2011). Under this point of view, mechanistic crop growth models coupled to the output of General/Regional Circulation Models (GCMs, RCMs) offer a valuable tool to evaluate crop responses to climatic change and this approach has been extensively used to describe crop yield distribution in response to climatic change considering changes in both mean climate and variability. In this work, we studied the effect of a warmer climate on crop yield distribution of durum wheat (Triticum turgidum L. subsp durum) in order to assess the economic significance of climatic change in a risk decision context. Specifically, the outputs of 6 RCMs (Tmin, Tmax, Rainfall, Global Radiation) (van der Linden and Mitchell 2009) have been statistically downscaled by a stochastic weather generator over eight sites across the Mediterranean basin and used to feed the crop growth model Sirius Quality. Three time slices were considered i) the present period PP (average of the period 1975-1990, [CO2]=350 ppm), 2020 (average of the period 2010-2030, SRES scenario A1b, [CO2]=415 ppm) and 2040 (average of the period 2030-2050, SRES scenario A1b, [CO2]=480 ppm). The effect of extreme climate events (i.e. heat stress at anthesis stage) was also considered. The outputs of these simulations were used to estimate the expected payout per hectare from insurance triggered when yields fall below a specific threshold defined as "the insured yield". For each site, the threshold was calculated as a fraction (70%) of the median of yield distribution under PP that represents the percentage of median yield above which indemnity payments are triggered. The results

  16. Management of the Extreme Events: Countering International Terrorism

    Directory of Open Access Journals (Sweden)

    Dr. Cristian Barna

    2011-12-01

    Full Text Available After the terrorism attacks of September 11, 2001, there is recognition by both the public and private sectors that one needs to rethink our strategy for dealing with these low probability but extreme consequence events. September 11, 2001 attacks against the United States raised numerous questions related to counter-terrorism, foreign policy, as well as national security in the United States and abroad. They also raised the fundamental question of who should pay for losses due to terrorism.The question of who should pay for terrorism risk prevention and sustainable coverage within a country is likely to be seen first as a matter of collective responsibility that each country has to consider – a societal choice

  17. Impacts of Land Use Management in Extreme Flood Events

    Science.gov (United States)

    O'Donnell, Greg; Ewen, John; Geris, Josie; Enda O'Connell, P.

    2010-05-01

    It is increasingly recognised internationally that the management of land and water is strongly interdependent, and that integrated management approaches are needed. There is evidence that modern land management practices have caused an increase in flood risk in rural upland areas, so there is the potential to use land management control as a tool in flood risk mitigation programmes. Flooding from historical extreme rainfall events must be considered when designing mitigation programmes, especially if the designs have to take into account the possibility that such extreme events will become more frequent in the future. The largest 90 minute rainfall ever recorded in the UK was 117mm, in 1967 in the Dunsop catchment, NW England (25 km^2). Extensive land management changes have recently been made in the catchment, including peat restoration, tree planting and reductions in sheep stocking density, and the analysis of the flooding in 1967 was undertaken as part of a wider study on the potential impact of the recent changes. An important part of the work on the 1967 flood was the separation of the various roles played in flood generation; particularly the roles played by runoff generation from the hillslopes and flow though the drainage/river network. A novel approach has been developed, for role separation, which involves tracking the downstream propagation of information through the catchment. This is achieved using reverse algorithmic differentiation (adjoint modelling) of a gridded catchment model that includes a detailed hydraulic model for the flow drainage/river network. Results will be shown for how various information and sensitivities vary spatially across the catchment, allowing conclusions to be drawn about the potential for using land management control in flood risk mitigation programmes.

  18. A summary of extreme scattering events and a descriptive model

    Science.gov (United States)

    Fiedler, R.; Dennison, B.; Johnston, K. J.; Waltman, E. B.; Simon, R. S.

    1994-08-01

    An ongoing monitoring program of compact extragalactic radio sources over the past 11 years has revealed many instances of unusual variations that cannot be explained using the standard models for intrinsic variability or normal refractive interstellar scintillation. The observations included simultaneous daily measurements at 2.695 and 8.085 GHz of 40 to 150 sources using the Green Bank interferometer over the period 1979 to 1989. Approximately 330 sources were also monitored with the National Radio Astronomy Observatory (NRAO) 300 foot radio telescope at 3.25 and 4.675 GHz over the 6 month period 1987 December to 1988 May. In total, 594 source-years of observations have been obtained, of which 4.8 yr constitutes the total time span of unusual variability. The unusual variations, denoted as extreme scattering events (ESEs), are summarized here. The most striking property of ESEs is their frequency dependence, in which departures from the quiescent flux density (by as much as 50% at 2.7 GHz) have no counterpart at 8.1 GHz. The single exception occurred in the 8.1 GHz light curve of 0954+658, which showed spiky variations during the 2.7 GHz event. To date,10 ESEs have been tentatively identified in the 2.7 GHz light curves of nine quasars. These ESEs appear to occur preferentially near loops in the Galactic foreground brightness distribution. A simple model based on diffraction or refraction through Galactic regions of unusually high electron density turbulence is presented.

  19. Developing a concept of social-ecological-technological systems to characterize resilience of urban areas and infrastructure to extreme events

    Science.gov (United States)

    Chester, M.; Grimm, N. B.; Redman, C.; Miller, T.; McPherson, T.; Munoz-Erickson, T.; Chandler, D. G.

    2015-12-01

    Climate change is widely considered one of the greatest challenges to global sustainability, with extreme events being the most immediate way that people experience this phenomenon. Urban areas are particularly vulnerable to these events given their location, concentration of people, and increasingly complex and interdependent infrastructure. We are developing a conceptual framework for urban social-ecological-technological systems (SETS) that will allow researchers and practitioners to assess how infrastructure can be resilient, provide ecosystem services, improve social well being, and exploit new technologies in ways that benefit urban populations. The framework integrates the three domains of social and equity issues, environmental quality and protection, and technical/engineering aspects, to form a concept of infrastructure that occurs at the intersection of the domains. Examples show how the more common socioecological systems and socially sensitive engineering approaches that fail to incorporate the third dimension may elevate vulnerability to climate-related disaster. The SETS conceptual framework bridges currently siloed social science, environmental science, and engineering approaches to significantly advance research into the structure, function, and emergent properties of SETS. Extreme events like heat waves in Phoenix; coastal and urban flooding in the wake of superstorm Sandy and following hurricanes in Miami, FL; drought in Mexico; and urban flooding in Baltimore, Portland, San Juan PR, Syracuse, and Valdivia, Chile provide examples of the impacts of and vulnerability to extreme events that demand a new approach. The infrastructure of the future must be resilient, leverage ecosystem services, improve social well being, and exploit new technologies in ways that benefit all segments of urban populations and are appropriate to the particular urban contexts. These contexts are defined not only by the biophysical environment but also by culture and

  20. Regional Frequency Analysis of extreme rainfall events, Tuscany (Italy)

    Science.gov (United States)

    Caporali, E.; Chiarello, V.; Rossi, G.

    2014-12-01

    The assessment of extreme hydrological events at sites characterized by short time series or where no data record exists has been mainly obtained by regional models. Regional frequency analysis based on the index variable procedure is implemented here to describe the annual maximum of rainfall depth of short durations in Tuscany region. The probability distribution TCEV - Two Component Extreme Value is used in the frame of the procedure for the parameters estimation based on a three levels hierarchical approach. The methodology deal with the delineation of homogeneous regions, the identification of a robust regional frequency distribution and the assessment of the scale factor, i.e. the index rainfall. The data set includes the annual maximum of daily rainfall of 351 gauge stations with at least 30 years of records, in the period 1916 - 2012, and the extreme rainfalls of short duration, 1 hour and 3, 6, 12, 24 hours. Different subdivisions hypotheses have been verified. A four regions subdivision, coincident with four subregions, which takes into account the orography, the geomorphological and climatic peculiarities of the Tuscany region, has been adopted. Particularly, for testing the regional homogeneity, the cumulate frequency distributions of the observed skewness and variation coefficients of the recorded times series, are compared with the theoretical frequency distribution obtained through a Monte Carlo technique. The related L-skewness and L-variation coefficients are also examined. The application of the Student t -test and the Wilcoxon test for the mean, as well as the χ2 was also performed. Further tests of subdivision hypotheses have been made through the application of discordancy D and heterogeneity H tests and the analysis of the observed and the theoretical TCEV model growth curves. For each region the daily rainfall growth curve has been estimated. The growth curves for the hourly duration have been estimated when the daily rainfall growth curve

  1. Multivariable extremes of metocean events (extreme and freak as the examples)

    Science.gov (United States)

    Lopatoukhin, L.; Boukhanovsky, A.

    2009-04-01

    Problem of estimation of high waves became clearer due to development of numerical models of wave hindcasting and forecasting, advent of reanalysis of meteorological data (as the input to models) and high performance computing. As a result it is possible to make continues hindcasting (30 years and longer duration) of wave parameters for any region. There exist different approaches to estimation of probability of wave heights with n-years return period. (Review of one dimensional methods and their comparison is published by World Meteorological Organization. See: WMO/TD-No. 1041, 2000, JCOMM Technical Report. www.jcommweb.net). In estimation of joint extremes (e.g., wave-heights and periods, wave heights and wind or current speed, wave heights in two different points simultaneously, etc) arise some problems. In particularly, the estimates with single return period belong to a set of pairs of random values. This problem may be solved by introduction of risk function. Some proposals will be presented. One of interesting extreme phenomenon is freak (or rogue) waves. Physical hypotheses of freak wave generation allow their arising in any place of an Ocean. There is no common definition of a freak wave. Freak waves are unusual not by their height, but also by the form and have to posses some principal difference from extreme wave. This uncommonness specified by means set of parameters; e.g., h>2.4hs, crest>0.65h, unusual steepness d of a wave and (or) it front or back slope, deep trough (twice as greater than preceding and subsequent waves), etc. Not all of these parameters are realized simultaneously. The approach regarded freak wave as multivariable random event is needed. The details of approach, comparison with other methods and known freak wave records will be presented. Investigations are supported by EC 6th Framework Targeted Project FP6-031489, Handling Waves.

  2. Observing and studying extreme low pressure events with altimetry.

    Science.gov (United States)

    Carrère, Loren; Mertz, Françoise; Dorandeu, Joel; Quilfen, Yves; Patoux, Jerome

    2009-01-01

    The ability of altimetry to detect extreme low pressure events and the relationship between sea level pressure and sea level anomalies during extra-tropical depressions have been investigated. Specific altimeter treatments have been developed for tropical cyclones and applied to obtain a relevant along-track sea surface height (SSH) signal: the case of tropical cyclone Isabel is presented here. The S- and C-band measurements are used because they are less impacted by rain than the Ku-band, and new sea state bias (SSB) and wet troposphere corrections are proposed. More accurate strong altimeter wind speeds are computed thanks to the Young algorithm. Ocean signals not related to atmospheric pressure can be removed with accuracy, even within a Near Real Time context, by removing the maps of sea level anomaly (SLA) provided by SSALTO/Duacs. In the case of Extra-Tropical Depressions, the classical altimeter processing can be used. Ocean signal not related to atmospheric pressure is along-track filtered. The sea level pressure (SLP)-SLA relationship is investigated for the North Atlantic, North Pacific and Indian oceans; three regression models are proposed allowing restoring an altimeter SLP with a mean error of 5 hPa if compared to ECMWF or buoys SLP. The analysis of barotropic simulation outputs points out the regional variability of the SLP/Model Sea Level relationship and the wind effects. PMID:22573955

  3. A simplified wave enhancement criterion for moving extreme events

    Science.gov (United States)

    Kudryavtsev, Vladimir; Golubkin, Pavel; Chapron, Bertrand

    2015-11-01

    An analytical model is derived to efficiently describe the wave energy distribution along the main transects of a moving extreme weather event. The model essentially builds on a generalization of the self-similar wave growth model and the assumption of a strongly dominant single spectral mode in a given quadrant of the storm. The criterion to anticipate wave enhancement with the generation of trapped abnormal waves defined as gr/ur2≈cT>(ur/V>)1/q, with r, u, and V, radial distance, average sustained wind speed, and translation velocity, respectively. Constants q and cT follow the fetch-law definitions. If forced during a sufficient time scale interval, also defined from this generalized self-similar wave growth model, waves can be trapped and large amplification of the wave energy will occur in the front-right storm quadrant. Remarkably, the group velocity and corresponding wavelength of outrunning wave systems will become wind speed independent and solely related to the translating velocity. The resulting significant wave height also only weakly depends on wind speed, and more strongly on the translation velocity. Compared to altimeter satellite measurements, the proposed analytical solutions for the wave energy distribution demonstrate convincing agreement. As analytically developed, the wave enhancement criterion can provide a rapid evaluation to document the general characteristics of each storm, especially the expected wavefield asymmetry.

  4. Observing and Studying Extreme Low Pressure Events with Altimetry

    Directory of Open Access Journals (Sweden)

    2009-02-01

    Full Text Available The ability of altimetry to detect extreme low pressure events and the relationship between sea level pressure and sea level anomalies during extra-tropical depressions have been investigated. Specific altimeter treatments have been developed for tropical cyclones and applied to obtain a relevant along-track sea surface height (SSH signal: the case of tropical cyclone Isabel is presented here. The S- and C-band measurements are used because they are less impacted by rain than the Ku-band, and new sea state bias (SSB and wet troposphere corrections are proposed. More accurate strong altimeter wind speeds are computed thanks to the Young algorithm. Ocean signals not related to atmospheric pressure can be removed with accuracy, even within a Near Real Time context, by removing the maps of sea level anomaly (SLA provided by SSALTO/Duacs. In the case of Extra-Tropical Depressions, the classical altimeter processing can be used. Ocean signal not related to atmospheric pressure is along-track filtered. The sea level pressure (SLP-SLA relationship is investigated for the North Atlantic, North Pacific and Indian oceans; three regression models are proposed allowing restoring an altimeter SLP with a mean error of 5 hPa if compared to ECMWF or buoys SLP. The analysis of barotropic simulation outputs points out the regional variability of the SLP/Model Sea Level relationship and the wind effects.

  5. Event-adjusted evaluation of weather and climate extremes

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    2013-01-01

    Roč. 1, 06 Sep (2013), s. 4481-4510. ISSN 2195-9269 R&D Projects: GA ČR(CZ) GAP209/11/1990 Institutional support: RVO:68378289 Keywords : weather extreme * climate extreme * extremity evaluation * return period * generalized extreme value distribution * region of influence Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.nat-hazards-earth-syst-sci-discuss.net/1/4481/2013/nhessd-1-4481-2013.pdf

  6. Event-adjusted evaluation of weather and climate extremes

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    2014-01-01

    Roč. 14, č. 2 (2014), s. 473-483. ISSN 1561-8633 R&D Projects: GA ČR(CZ) GAP209/11/1990 Institutional support: RVO:68378289 Keywords : weather extreme * climate extreme * extremity evaluation * return period * generalized extreme value distribution * region of influence Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.735, year: 2014 http://www.nat-hazards-earth-syst-sci.net/14/473/2014/nhess-14-473-2014.pdf

  7. Extreme climatic events: reducing ecological and social systems vulnerabilities

    International Nuclear Information System (INIS)

    The Earth has to face more and more devastating extreme events. Between 1970 and 2009, at the worldwide scale, the 25 most costly catastrophes all took place after 1987, and for more than half of them after 2001. Among these 25 catastrophes, 23 were linked to climate conditions. France was not spared: the December 1999 storms led to 88 deaths, deprived 3.5 million households of electricity and costed more than 9 billion euros. The 2003 heat wave led to about 15000 supernumerary deaths between August 1 and August 20. The recent Xynthia storm, with its flood barrier ruptures, provoked 53 deaths in addition to many other tragedies that took place in areas liable to flooding. In the present day context of climate change, we know that we must be prepared to even more dangerous events, sometimes unexpected before. These events can have amplified effects because of the urban development, the overpopulation of coastal areas and the anthropization of natural environments. They represent real 'poverty traps' for the poorest countries of the Earth. The anticipation need is real but is our country ready to answer it? Does it have a sufficient contribution to international actions aiming at reducing risks? Is his scientific information suitable? France is not less vulnerable than other countries. It must reinforce its prevention, its response and resilience capacities in the framework of integrated policies of catastrophes risk management as well as in the framework of climate change adaptation plans. This reinforcement supposes the development of vigilance systems with a better risk coverage and benefiting by the advances gained in the meteorology and health domains. It supposes a town and country planning allowing to improve the viability of ecological and social systems - in particular by protecting their diversity. Finally, this reinforcement requires inciting financial coverage solutions for catastrophes prevention and for their management once they have taken place. A

  8. The XIV Global Warming International Conference & Expo (GWXIV)——Global extreme events

    Institute of Scientific and Technical Information of China (English)

    JamesA.Roberts

    2004-01-01

    The focus of this year's conference is Global Extreme Events, characterized as large-scale climatic effects that have been increasing in magnitude and frequency. Prof. Sinyan Shen, Chairman of the GW International Program Committee, has been leading the world on Global Extreme Events and Emergency Response. In the long term climate change will cause the Earth to transit to another equilibrium state through many oscillations in climatic pattern. Global warming causes extreme events and bad weather in the near term. The immediate

  9. An extreme CO pollution event over Indonesia measured by the MOPITT instrument

    OpenAIRE

    F. Nichitiu; Drummond, J. R.; Kar, J.; Zou, J.

    2009-01-01

    In the fall of 2006, the Measurements Of Pollution In The Troposphere (MOPITT) instrument on the Terra satellite observed an extremely high Carbon monoxide (CO) concentration over Indonesia. This extreme event was caused by huge fire activity during the 2006 El Nino event. From our comparison with other high CO pollution events over Indonesia during similar and moderate El Nino events, we conclude that the 2006 fire activity, which caused large-scale pollution in this region, was probably amp...

  10. Risk of extreme events in the configuration of priority systems

    International Nuclear Information System (INIS)

    This paper presents a reliability-based framework for the configuration of priority systems that control the risks of extreme transaction latencies. Modeling of priority systems can be computationally complex and lack robustness with respect to the feasible variations of such systems. The analyses tend to be ad hoc and overly particular to the application at hand. Furthermore, modeling of priority systems has focused on assessment of the average latencies, rather than on the potential for extremes of latency. The developed framework includes (i) a compact notation useful for modeling of priority systems, (ii) assessment of the risk of extreme latencies, and (iii) multiobjective analysis for the tuning of system parameters. An acceptable balance is sought among multiple risks of extreme transaction latencies. The framework is demonstrated in the configuration of an e-business server to minimize the lost transactions, e.g. 'purchase' requests for which a customer needs to wait longer than 8 s

  11. The December 2008 flood event in Rome: Was it really an extreme event?

    Science.gov (United States)

    Lastoria, B.; Mariani, S.; Casaioli, M.; Bussettini, M.

    2009-04-01

    In mid December 2008, Italy suffered bad weather with heavy snowfall blanketing the north and strong winds and downpours pelting the centre-south. In particular, during the period between 10th and 12th December, intense precipitation struck the Tyrrhenian Sea side of the peninsula, inducing a flood event, which captured the attention of the national and international media, on the Tiber river and on its tributary, the Aniene. The relevance of the event was caused by the actual damages occurred in several zones over Rome area, in particular due to the downpours and to damages which would have occurred if Tiber river had overflowed its banks. The event, which was initially considered as extreme, was indeed severe but not so exceptional as shown by the meteo-hydrological post-event analysis. The peak water level of 12.55 m, recorded on 13th December at 1:30 a.m. (local time) at the Ripetta station, which is situated along the Tiber river in the centre of Rome, was higher than those observed during the last ten years (which to the utmost reached 11.41 m in December 2005). However, it did not reach the historical maximum of 16.90 m observed in 1937. Moreover, on the basis of the Ripetta historical series, such a level is associated to an ordinary flood event. Even if the flood was ordinary, a state of emergency was declared by the Rome's Mayor, since the event caused severe damages by disrupting flight and train services, blocking off major roads leading into Rome, flooding underpasses and sealing off industrial activities sited in the flooded areas, in particular nearby the confluence of the Aniene river with the Tiber river. In addition, hundreds of people were evacuated and a woman died in a her car which was submerged by a wave of water and mud in an underpass. Given these premises, the present work examines the relation between a severe, but not extraordinary, event and the considerable damages that occurred as a consequence. First, the meteorological evolution of

  12. Impacts of the Future Changes in Extreme Events on the Regional Crop Yield in Turkey

    Science.gov (United States)

    An, Nazan; Turp, M. Tufan; Ozturk, Tugba; Kurnaz, M. Levent

    2016-04-01

    The changes in extreme events caused by climate change have the greatest impact on agricultural sector specifically crop yield. Therefore, it requires a clear understanding of how extreme events affect the crop yield and how it causes high economic losses. In this research, we cover the relationship between extreme events and the crop yield in Turkey for the period of 2020 - 2045 with respect to 1980 - 2005. We focus on the role of those extreme event causing natural disasters on the regional crop yield. This research comprises 2 parts. In the first part, the projection is performed according to the business as usual scenario of IPCC, RCP8.5, via the RegCM4.4 in order to obtain extreme event indices required for the crop assessment. In the second part, the crop yield and the extreme event indices are combined by applying the econometric analysis in order to see the relationship between natural disasters and crop yield. The risks for crop yield caused by the extreme events are estimated and interpreted. This study aims to assess the effect of frequency of expected extreme events on the crop yield at the cropland of Turkey. This research has been supported by Boǧaziçi University Research Fund Grant Number 10421.

  13. Research frontiers in climate change: Effects of extreme meteorological events on ecosystems

    International Nuclear Information System (INIS)

    Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that modifications in extreme weather events pose stronger threats to ecosystem functioning than global trends and shifts in average conditions. As ecosystem functioning is connected with ecological services, this has far-reaching effects on societies in the 21. century. Here, we: (i) present the rationale for the increasing frequency and magnitude of extreme weather events in the near future; (ii) discuss recent findings on meteorological extremes and summarize their effects on ecosystems and (iii) identify gaps in current ecological climate change research. (authors)

  14. Co-dependence of Extreme Events in High Frequency FX Returns

    OpenAIRE

    Arnold Polanski; Evarist Stoja

    2013-01-01

    In this paper, we investigate extreme events in high frequency, multivariate FX returns within a purposely built framework. We generalize univariate tests and concepts to multidimensional settings and employ these novel techniques for parametric and nonparametric analysis. In particular, we investigate and quantify the co-dependence of cross-sectional and intertemporal extreme events. We find evidence of the cubic law of extreme returns, their increasing and asymmetric dependence and of the s...

  15. Rehabilitation of Existing Structures Subjected to Extreme Events

    Directory of Open Access Journals (Sweden)

    Corneliu Bob

    2007-01-01

    Full Text Available The paper presents the characteristics of existing structures under extreme actions, general and specific rehabilitation solutions detailed for reinforced concrete and masonry structures. Rehabilitation of different types of existing structures are described: a reinforced concrete framed structure presenting major detailing vulnerabilities at seismic actions; an apartment house affected by an explosion; two masonry buildings affected by a recent earthquake.

  16. Uncertainty related to Environmental Data and Estimated Extreme Events

    DEFF Research Database (Denmark)

    Burcharth, H. F.

    including those corresponding to extreme estimates typically used for design purposes. Basically a design condition is made up of a set of parameter values stemming from several environmental parameters. To be able to evaluate the uncertainty related to design states one must know the corresponding joint...

  17. Flood-risk mapping: contributions towards an enhanced assessment of extreme events and associated risks

    OpenAIRE

    Büchele, B.; Kreibich, H.; A. Kron; Thieken, A.; Ihringer, J.; P. Oberle; B. Merz; F. Nestmann

    2006-01-01

    Currently, a shift from classical flood protection as engineering task towards integrated flood risk management concepts can be observed. In this context, a more consequent consideration of extreme events which exceed the design event of flood protection structures and failure scenarios such as dike breaches have to be investigated. Therefore, this study aims to enhance existing methods for hazard and risk assessment for extreme events and is divided into three parts. In the first part, a reg...

  18. Extremeness of meteorological quantities as an indicator of extreme precipitation events

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    Zurich : ETH, 2006 - (Molnar, P.), s. 175-179 ISBN 3-909386-65-2. [International workshop on precipitation in urban areas /7./. St. Moritz (CH), 07.12.2006-10.12.2006] R&D Projects: GA AV ČR KJB3042404; GA ČR GA205/04/0114; GA MŠk OC 112 Institutional research plan: CEZ:AV0Z30420517 Keywords : Extremeness * extreme precipitation * summer flood * extremity index * synoptic situation Subject RIV: DG - Athmosphere Sciences, Meteorology

  19. On the two steps threshold selection for over-threshold modelling of extreme events

    Science.gov (United States)

    Bernardara, Pietro; Mazas, Franck; Weiss, Jerome; Andreewsky, Marc; Kergadallan, Xavier; Benoit, Michel; Hamm, Luc

    2013-04-01

    The estimation of the probability of occurrence of extreme events is traditionally achieved by fitting a probability distribution on a sample of extreme observations. In particular, the extreme value theory (EVT) states that values exceeding a given threshold converge through a Generalized Pareto Distribution (GPD) if the original sample is composed of independent and identically distributed values. However, the temporal series of sea and ocean variables usually show strong temporal autocorrelation. Traditionally, in order to select independent events for the following statistical analysis, the concept of a physical threshold is introduced: events that excess that threshold are defined as "extreme events". This is the so-called "Peak Over a Threshold (POT)" sampling, widely spread in the literature and currently used for engineering applications among many others. In the past, the threshold for the statistical sampling of extreme values asymptotically convergent toward GPD and the threshold for the physical selection of independent extreme events were confused, as the same threshold was used for both sampling data and to meet the hypothesis of extreme value convergence, leading to some incoherencies. In particular, if the two steps are performed simultaneously, the number of peaks over the threshold can increase but also decrease when the threshold decreases. This is logic in a physical point of view, since the definition of the sample of "extreme events" changes, but is not coherent with the statistical theory. We introduce a two-steps threshold selection for over-threshold modelling, aiming to discriminate (i) a physical threshold for the selection of extreme and independent events, and (ii) a statistical threshold for the optimization of the coherence with the hypothesis of the EVT. The former is a physical events identification procedure (also called "declustering") aiming at selecting independent extreme events. The latter is a purely statistical optimization

  20. (When and where) Do extreme climate events trigger extreme ecosystem responses? - Development and initial results of a holistic analysis framework

    Science.gov (United States)

    Hauber, Eva K.; Donner, Reik V.

    2015-04-01

    In the context of ongoing climate change, extremes are likely to increase in magnitude and frequency. One of the most important consequences of these changes is that the associated ecological risks and impacts are potentially rising as well. In order to better anticipate and understand these impacts, it therefore becomes more and more crucial to understand the general connection between climate extremes and the response and functionality of ecosystems. Among other region of the world, Europe presents an excellent test case for studies concerning the interaction between climate and biosphere, since it lies in the transition region between cold polar and warm tropical air masses and thus covers a great variety of different climatic zones and associated terrestrial ecosystems. The large temperature differences across the continent make this region particularly interesting for investigating the effects of climate change on biosphere-climate interactions. However, previously used methods for defining an extreme event typically disregard the necessity of taking seasonality as well as seasonal variance appropriately into account. Furthermore, most studies have focused on the impacts of individual extreme events instead of considering a whole inventory of extremes with their respective spatio-temporal extents. In order to overcome the aforementioned research gaps, this work introduces a new approach to studying climate-biosphere interactions associated with extreme events, which comprises three consecutive steps: (1) Since Europe exhibits climatic conditions characterized by marked seasonality, a novel method is developed to define extreme events taking into account the seasonality in all quantiles of the probability distribution of the respective variable of interest. This is achieved by considering kernel density estimates individually for each observation date during the year, including the properly weighted information from adjacent dates. By this procedure, we obtain

  1. Prediction of extreme rainfall event using weather pattern recognition and support vector machine classifier

    Science.gov (United States)

    Nayak, Munir Ahmad; Ghosh, Subimal

    2013-11-01

    A major component of flood alert broadcasting is the short-term prediction of extreme rainfall events, which remains a challenging task, even with the improvements of numerical weather prediction models. Such prediction is a high priority research challenge, specifically in highly urbanized areas like Mumbai, India, which is extremely prone to urban flooding. Here, we attempt to develop an algorithm based on a machine learning technique, support vector machine (SVM), to predict extreme rainfall with a lead time of 6-48 h in Mumbai, using mesoscale (20-200 km) and synoptic scale (200-2,000 km) weather patterns. The underlying hypothesis behind this algorithm is that the weather patterns before (6-48 h) extreme events are significantly different from those of normal weather days. The present algorithm attempts to identify those specific patterns for extreme events and applies SVM-based classifiers for extreme rainfall classification and prediction. Here, we develop the anomaly frequency method (AFM), where the predictors (and their patterns) for SVM are identified with the frequency of high anomaly values of weather variables at different pressure levels, which are present before extreme events, but absent for non-extreme conditions. We observe that weather patterns before the extreme rainfall events during nighttime (1800 to 0600Z) is different from those during daytime (0600 to 1800Z) and, accordingly, we develop a two-phase support vector classifier for extreme prediction. Though there are false alarms associated with this prediction method, the model predicts all the extreme events well in advance. The performance is compared with the state-of-the-art statistical technique fingerprinting approach and is observed to be better in terms of false alarm and prediction.

  2. An Ensemble Approach to Extreme Space Weather Event Probability -- A First Look

    Science.gov (United States)

    Jonas, S.; Fronczyk, K.; McCarron, E.; Pratt, L. M.

    2015-12-01

    An extreme space weather event has the potential to disrupt or damage infrastructure systems and technologies that many societies rely on for economic and social wellbeing. Space weather events occur regularly, but extreme events occur less frequently with only several historical examples over the last 160 years. During the past decade, published works have (1) forensically examined the physical characteristics of the extreme historical events; and (2) discussed the probability or return rate of select extreme geomagnetic disturbances, including the 1859 Carrington event. Here we present an analysis of several of these studies. We created a unified statistical framework to visualize previous analyses, and developed a model from an ensemble using statistical methods. We look at geomagnetic disturbance probability across multiple return periods. We discuss what the most likely 100-year extreme event (a parameter of interest to policy makers and planners) and the return period for other extreme historical events. We discuss the current state of these analyses, their utility to policy makers and planners, the current limitations (in data and understanding) when compared to other hazards, and the gaps that need to be filled to enhance space weather risk assessments.

  3. Indications of an extreme event deposits along the west coast of India: evidences from GPR investigations

    Digital Repository Service at National Institute of Oceanography (India)

    Loveson, V.J.; Gujar, A.R.; Iyer, S.D.; Srivastava, P.; Tirodkar, G.; Luis, R.A.A.

    to an extreme event. Sand samples were collected from two trial pits along the GPR profiles to understand the sedimentology and mineralogy in the backshore area. These data together with beach profiles and geomorphological maps suggest that the sands were...

  4. Combining regional climate and national human development scenarios to estimate future vulnerability to extreme climate and weather events

    Science.gov (United States)

    Patt, A.; Nussbaumer, P.

    2009-04-01

    Extreme climate and weather events such as droughts, floods, and tropical cyclones account for over 60% of the loss of life, and over 90% of total impacts, from natural disasters. Both observed trends and global climate models (GCMs) suggest that the frequency and intensity of extreme events is increasing, and will continue to increase as a result of climate change. Among planners and policy-makers at both national and international levels there is thus concern that this rise in extreme events will lead to greater losses in the future. Since low levels of development are associated with greater numbers of people killed and needing emergency assistance from natural disasters, the concern is most pronounced for least developed countries. If, however, these countries make substantial improvements in their levels of human development, as leading forecasters suggest may be the case over the coming decades, then their vulnerability to extreme events may fall. In this study, we examine the potential combined effects of increased extreme event frequency and improved levels of human development, to generate scenarios of risk levels into the second half of the century. It is the African continent for which these results may be the most relevant, since it is widely viewed as most vulnerable to increased risks from climate change; we focus on the particular country of Mozambique, which has experienced high losses from droughts, floods, and tropical cyclones in recent decades, and stands out as being among the most vulnerable in Africa. To assess the change in risk levels from the present until 2060, we pull together three pieces of analysis. The first is a statistical analysis of the losses from 1990-2007 from climate-related disasters, using national level data from the Centre for Research on the Epidemiology of Disasters (CRED) and the United Nations. From this analysis, we establish statistical relationships between several drivers of vulnerability—including country size

  5. Increased frequency of extreme La Niña events under greenhouse warming

    Science.gov (United States)

    Cai, Wenju; Wang, Guojian; Santoso, Agus; McPhaden, Michael J.; Wu, Lixin; Jin, Fei-Fei; Timmermann, Axel; Collins, Mat; Vecchi, Gabriel; Lengaigne, Matthieu; England, Matthew H.; Dommenget, Dietmar; Takahashi, Ken; Guilyardi, Eric

    2015-02-01

    The El Niño/Southern Oscillation is Earth’s most prominent source of interannual climate variability, alternating irregularly between El Niño and La Niña, and resulting in global disruption of weather patterns, ecosystems, fisheries and agriculture. The 1998-1999 extreme La Niña event that followed the 1997-1998 extreme El Niño event switched extreme El Niño-induced severe droughts to devastating floods in western Pacific countries, and vice versa in the southwestern United States. During extreme La Niña events, cold sea surface conditions develop in the central Pacific, creating an enhanced temperature gradient from the Maritime continent to the central Pacific. Recent studies have revealed robust changes in El Niño characteristics in response to simulated future greenhouse warming, but how La Niña will change remains unclear. Here we present climate modelling evidence, from simulations conducted for the Coupled Model Intercomparison Project phase 5 (ref. ), for a near doubling in the frequency of future extreme La Niña events, from one in every 23 years to one in every 13 years. This occurs because projected faster mean warming of the Maritime continent than the central Pacific, enhanced upper ocean vertical temperature gradients, and increased frequency of extreme El Niño events are conducive to development of the extreme La Niña events. Approximately 75% of the increase occurs in years following extreme El Niño events, thus projecting more frequent swings between opposite extremes from one year to the next.

  6. Statistics of extreme events in Chinese stock markets

    International Nuclear Information System (INIS)

    We investigate the impact of financial factors on daily volume recurrent time intervals in the developing Chinese stock markets. The tails of probability distribution functions (PDFs) of volume recurrent intervals behave as a power-law, and the scaling exponent decreases with the increase of stock lifetime, which are similar to those in the US stock markets, and they are typical representatives of developed markets. The difference is that the power-law exponent values remain almost the same with the changes of market capitalization, mean volume, and mean trading value, respectively. These findings enrich the results for event statistics for financial markets. (interdisciplinary physics and related areas of science and technology)

  7. Trends in extreme rainfall events in Benin (West Africa), 1960-2000

    OpenAIRE

    Hountondji, Yvon; De Longueville, Florence; Ozer, Pierre

    2011-01-01

    Global dataset of derived indicators has been compiled to clarify whether the frequency and / or the severity of rainfall extremes changed during the 1960 – 2000 period in the Republic of Benin in West Africa. This period provides the best spatial coverage of homogenous daily series, which can be used for calculating the proportion of global land area exhibiting a significant change in extreme or severe rainfall. We selected 12 indicators of extreme climatic events that are based on daily tot...

  8. Extreme rainfall analysis based on precipitation events classification in Northern Italy

    Science.gov (United States)

    Campo, Lorenzo; Fiori, Elisabetta; Molini, Luca

    2016-04-01

    Extreme rainfall statistical analysis is constituted by a consolidated family of techniques that allows to study the frequency and the statistical properties of the high-intensity meteorological events. This kind of techniques is well established and comprehends standards approaches like the GEV (Generalized Extreme Value) or TCEV (Two Components Extreme Value) probability distribution fit of the data recorded in a given raingauge on a given location. Regionalization techniques, that are aimed to spatialize the analysis on medium-large regions are also well established and operationally used. In this work a novel procedure is proposed in order to statistically characterize the rainfall extremes in a given region, basing on a "event-based" approach. Given a temporal sequence of continuous rain maps, an "event" is defined as an aggregate, continuous in time and space, of cells whose rainfall height value is above a certain threshold. Basing on this definition it is possible to classify, on a given region and for a given period, a population of events and characterize them with a number of statistics, such as their total volume, maximum spatial extension, duration, average intensity, etc. Thus, the population of events so obtained constitutes the input of a novel extreme values characteriztion technique: given a certain spatial scale, a mobile window analysis is performed and all the events that fall in the window are anlysed from an extreme value point of view. For each window, the extreme annual events are considered: maximum total volume, maximum spatial extension, maximum intensity, maximum duration are all considered for an extreme analysis and the corresponding probability distributions are fitted. The analysis allows in this way to statistically characterize the most intense events and, at the same time, to spatialize these rain characteristics exploring their variability in space. This methodology was employed on rainfall fields obtained by interpolation of

  9. Extreme events as sources of health vulnerability: Drought as an example

    OpenAIRE

    Ebi, Kristie L.; Kathryn Bowen

    2016-01-01

    The health risks of climate change arise from the interactions of the hazards associated with a changing climate (e.g. increases in the frequency and intensity of extreme weather and climate events, such as drought), the communities exposed to those hazards, the susceptibility of communities to adverse health impacts when exposed, and the capacity to prepare for and cope with the hazard. However, there is a very limited understanding of how extreme weather and climate events could themselves ...

  10. The differential effects of increasing frequency and magnitude of extreme events on coral populations

    OpenAIRE

    Fabina, NS; Baskett, ML; Gross, K.

    2015-01-01

    © 2015 by the Ecological Society of America. Extreme events, which have profound ecological consequences, are changing in both frequency and magnitude with climate change. Because extreme temperatures induce coral bleaching, we can explore the relative impacts of changes in frequency and magnitude of high temperature events on coral reefs. Here, we combined climate projections and a dynamic population model to determine how changing bleaching regimes influence coral persistence. We additional...

  11. Effects of management regimes and extreme climatic events on plant population viability in Eryngium alpinum

    OpenAIRE

    Andrello, Marco; Bizoux, Jean-Philippe; BARBET-MASSIN, morgane; Gaudeul, Myriam; Nicolè, Florence; Till-Bottraud, Irène

    2012-01-01

    Extreme climatic events like the 2003 summer heatwave and inappropriate land management can threaten the existence of rare plants. We studied the response of Eryngium alpinum, a vulnerable species, to this extreme climatic event and different agricultural practices. A demographic study was conducted in seven field sites between 2001 and 2010. Stage-specific vital rates were used to parameterize matrix population models and perform stochastic projections to calculate population growth rates an...

  12. Triggering extreme events at the nanoscale in photonic seas

    Science.gov (United States)

    Liu, C.; van der Wel, R. E. C.; Rotenberg, N.; Kuipers, L.; Krauss, T. F.; di Falco, A.; Fratalocchi, A.

    2015-04-01

    Hurricanes, tsunamis, rogue waves and tornadoes are rare natural phenomena that embed an exceptionally large amount of energy, which appears and quickly disappears in a probabilistic fashion. This makes them difficult to predict and hard to generate on demand. Here we demonstrate that we can trigger the onset of rare events akin to rogue waves controllably, and systematically use their generation to break the diffraction limit of light propagation. We illustrate this phenomenon in the case of a random field, where energy oscillates among incoherent degrees of freedom. Despite the low energy carried by each wave, we illustrate how to control a mechanism of spontaneous synchronization, which constructively builds up the spectral energy available in the whole bandwidth of the field into giant structures, whose statistics is predictable. The larger the frequency bandwidth of the random field, the larger the amplitude of rare events that are built up by this mechanism. Our system is composed of an integrated optical resonator, realized on a photonic crystal chip. Through near-field imaging experiments, we record confined rogue waves characterized by a spatial localization of 206 nm and with an ultrashort duration of 163 fs at a wavelength of 1.55 μm. Such localized energy patterns are formed in a deterministic dielectric structure that does not require nonlinear properties.

  13. Triggering extreme events at the nanoscale in photonic seas

    KAUST Repository

    Liu, Changxu

    2015-03-09

    Hurricanes, tsunamis, rogue waves and tornadoes are rare natural phenomena that embed an exceptionally large amount of energy, which appears and quickly disappears in a probabilistic fashion. This makes them difficult to predict and hard to generate on demand. Here we demonstrate that we can trigger the onset of rare events akin to rogue waves controllably, and systematically use their generation to break the diffraction limit of light propagation. We illustrate this phenomenon in the case of a random field, where energy oscillates among incoherent degrees of freedom. Despite the low energy carried by each wave, we illustrate how to control a mechanism of spontaneous synchronization, which constructively builds up the spectral energy available in the whole bandwidth of the field into giant structures, whose statistics is predictable. The larger the frequency bandwidth of the random field, the larger the amplitude of rare events that are built up by this mechanism. Our system is composed of an integrated optical resonator, realized on a photonic crystal chip. Through near-field imaging experiments, we record confined rogue waves characterized by a spatial localization of 206 nm and with an ultrashort duration of 163 fs at a wavelength of 1.55 μm. Such localized energy patterns are formed in a deterministic dielectric structure that does not require nonlinear properties.

  14. Power Outages, Extreme Events and Health: a Systematic Review of the Literature from 2011-2012

    Science.gov (United States)

    Klinger, Chaamala; Landeg, Owen; Murray, Virginia

    2014-01-01

    Background Extreme events (e.g. flooding) threaten critical infrastructure including power supplies. Many interlinked systems in the modern world depend on a reliable power supply to function effectively. The health sector is no exception, but the impact of power outages on health is poorly understood. Greater understanding is essential so that adverse health impacts can be prevented and/or mitigated. Methods We searched Medline, CINAHL and Scopus for papers about the health impacts of power outages during extreme events published in 2011-2012. A thematic analysis was undertaken on the extracted information. The Public Health England Extreme Events Bulletins between 01/01/2013 - 31/03/2013 were used to identify extreme events that led to power outages during this three-month period. Results We identified 20 relevant articles. Power outages were found to impact health at many levels within diverse settings. Recurrent themes included the difficulties of accessing healthcare, maintaining frontline services and the challenges of community healthcare. We identified 52 power outages in 19 countries that were the direct consequence of extreme events during the first three months of 2013. Conclusions To our knowledge, this is the first review of the health impacts of power outages. We found the current evidence and knowledge base to be poor. With scientific consensus predicting an increase in the frequency and magnitude of extreme events due to climate change, the gaps in knowledge need to be addressed in order to mitigate the impact of power outages on global health. PMID:24459613

  15. Extreme events as sources of health vulnerability: Drought as an example

    Directory of Open Access Journals (Sweden)

    Kristie L. Ebi

    2016-03-01

    Full Text Available The health risks of climate change arise from the interactions of the hazards associated with a changing climate (e.g. increases in the frequency and intensity of extreme weather and climate events, such as drought, the communities exposed to those hazards, the susceptibility of communities to adverse health impacts when exposed, and the capacity to prepare for and cope with the hazard. However, there is a very limited understanding of how extreme weather and climate events could themselves be sources of vulnerability. Drought is used as an example of an extreme event that can simultaneously be a current hazard and can directly and indirectly influence future vulnerability. A better understanding of droughts and other extreme events as sources of vulnerability is needed, including (i the patterns of risks and how these could change over time, (ii the reasons for any changes, (iii how these risks could affect human health and well-being, and (iv the longer-term consequences of extreme events for vulnerability. This knowledge will become increasingly important for managing risks to health as the frequency and intensity of extreme weather and climate events increase with climate change.

  16. Temporal energy partitions of Florida extreme sea level events as a function of Atlantic multidecadal oscillation

    Directory of Open Access Journals (Sweden)

    J. Park

    2010-06-01

    Full Text Available An energy-conservative metric based on the discrete wavelet transform is applied to assess the relative energy distribution of extreme sea level events across different temporal scales. The metric is applied to coastal events at Key West and Pensacola Florida as a function of two Atlantic Multidecadal Oscillation (AMO regimes. Under AMO warm conditions there is a small but significant redistribution of event energy from nearly static into more dynamic (shorter duration timescales at Key West, while at Pensacola the AMO-dependent changes in temporal event behaviour are less pronounced. Extreme events with increased temporal dynamics might be consistent with an increase in total energy of event forcings which may be a reflection of more energetic storm events during AMO warm phases. As dynamical models mature to the point of providing regional climate index predictability, coastal planners may be able to consider such temporal change metrics in planning scenarios.

  17. Temporal energy partitions of Florida extreme sea level events as a function of Atlantic multidecadal oscillation

    Directory of Open Access Journals (Sweden)

    J. Park

    2010-03-01

    Full Text Available An energy-conservative metric based on the discrete wavelet transform is applied to assess the relative energy distribution of non-stationary extreme sea level events across different temporal scales. The metric is applied to coastal events at Key West and Pensacola Florida as a function of two Atlantic Multidecadal Oscillation (AMO regimes. Under AMO warm conditions there is a small but significant redistribution of event energy from nearly static into more dynamic timescales at Key West, while at Pensacola the AMO-dependent changes in temporal event behaviour are less pronounced. Extreme events with increased temporal dynamics are consistent with an increase in total energy of event forcings which may be a reflection of more energetic storm events during AMO warm phases. As dynamical models mature to the point of providing regional climate index predictability, coastal planners may be able to consider such temporal change metrics in planning scenarios.

  18. Expected impacts of climate change on extreme climate events; Impacts du changement climatique sur les evenements climatiques extremes

    Energy Technology Data Exchange (ETDEWEB)

    Planton, S.; Deque, M.; Chauvin, F. [Meteo-France, Centre National de Recherches Meteorologiques/groupe d' Etude de l' Atmosphere Meteorologique (CNRM/GAME), 31 - Toulouse (France); Terray, L. [Centre Europeen de Recherches Avancees en Calcul Scientifique, 31 - Toulouse (France)

    2008-09-15

    An overview of the expected change of climate extremes during this century due to greenhouse gases and aerosol anthropogenic emissions is presented. The most commonly used methodologies rely on the dynamical or statistical down-scaling of climate projections, performed with coupled atmosphere-ocean general circulation models. Either of dynamical or of statistical type, down-scaling methods present strengths and weaknesses, but neither their validation on present climate conditions, nor their potential ability to project the impact of climate change on extreme event statistics allows one to give a specific advantage to one of the two types. The results synthesized in the last IPCC report and more recent studies underline a convergence for a very likely increase in heat wave episodes over land surfaces, linked to the mean warming and the increase in temperature variability. In addition, the number of days of frost should decrease and the growing season length should increase. The projected increase in heavy precipitation events appears also as very likely over most areas and also seems linked to a change in the shape of the precipitation intensity distribution. The global trends for drought duration are less consistent between models and down-scaling methodologies, due to their regional variability. The change of wind-related extremes is also regionally dependent, and associated to a poleward displacement of the mid-latitude storm tracks. The specific study of extreme events over France reveals the high sensitivity of some statistics of climate extremes at the decadal time scale as a consequence of regional climate internal variability. (authors)

  19. Analysis of extreme top event frequency percentiles based on fast probability integration

    International Nuclear Information System (INIS)

    In risk assessments, a primary objective is to determine the frequency with which a collection of initiating and basic events, Ee leads to some undesired top event, T. Uncertainties in the occurrence rates, xt, assigned to the initiating and basic events cause uncertainty in the top event frequency, zT. The quantification of the uncertainty in zT is an essential part of risk assessment called uncertainty analysis. In the past, it has been difficult to evaluate the extreme percentiles of output variables like zT. Analytic methods such as the method of moments do not provide estimates of output percentiles and the Monte Carlo (MC) method can be used to estimate extreme output percentiles only by resorting to large sample sizes. A promising altemative to these methods is the fast probability integration (FPI) methods. These methods approximate the integrals of multi-variate functions, representing percentiles of interest, without recourse to multi-dimensional numerical integration. FPI methods give precise results and have been demonstrated to be more efficient than MC methods for estimating extreme output percentiles. FPI allows the analyst to choose extreme percentiles of interest and perform sensitivity analyses in those regions. Such analyses can provide valuable insights as to the events driving the top event frequency response in extreme probability regions. In this paper, FPI methods are adapted a) to precisely estimate extreme top event frequency percentiles and b) to allow the quantification of sensitivity measures at these extreme percentiles. In addition, the relative precision and efficiency of alternative methods for treating lognormally distributed inputs is investigated. The methodology is applied to the top event frequency expression for the dominant accident sequence from a risk assessment of Grand Gulf nuclear power plant

  20. Impact of climate change on extreme rainfall events and flood risk in India

    Indian Academy of Sciences (India)

    P Guhathakurta; O P Sreejith; P A Menon

    2011-06-01

    The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas during recent years motivate us to study long-term changes in extreme rainfall over India. The analysis of the frequency of rainy days, rain days and heavy rainfall days as well as one-day extreme rainfall and return period has been carried out in this study to observe the impact of climate change on extreme rainfall events and flood risk in India. The frequency of heavy rainfall events are decreasing in major parts of central and north India while they are increasing in peninsular, east and north east India. The study tries to bring out some of the interesting findings which are very useful for hydrological planning and disaster managements. Extreme rainfall and flood risk are increasing significantly in the country except some parts of central India.

  1. Roadmap on optical rogue waves and extreme events

    Science.gov (United States)

    Akhmediev, Nail; Kibler, Bertrand; Baronio, Fabio; Belić, Milivoj; Zhong, Wei-Ping; Zhang, Yiqi; Chang, Wonkeun; Soto-Crespo, Jose M.; Vouzas, Peter; Grelu, Philippe; Lecaplain, Caroline; Hammani, K.; Rica, S.; Picozzi, A.; Tlidi, Mustapha; Panajotov, Krassimir; Mussot, Arnaud; Bendahmane, Abdelkrim; Szriftgiser, Pascal; Genty, Goery; Dudley, John; Kudlinski, Alexandre; Demircan, Ayhan; Morgner, Uwe; Amiraranashvili, Shalva; Bree, Carsten; Steinmeyer, Günter; Masoller, C.; Broderick, Neil G. R.; Runge, Antoine F. J.; Erkintalo, Miro; Residori, S.; Bortolozzo, U.; Arecchi, F. T.; Wabnitz, Stefan; Tiofack, C. G.; Coulibaly, S.; Taki, M.

    2016-06-01

    The pioneering paper ‘Optical rogue waves’ by Solli et al (2007 Nature 450 1054) started the new subfield in optics. This work launched a great deal of activity on this novel subject. As a result, the initial concept has expanded and has been enriched by new ideas. Various approaches have been suggested since then. A fresh look at the older results and new discoveries has been undertaken, stimulated by the concept of ‘optical rogue waves’. Presently, there may not by a unique view on how this new scientific term should be used and developed. There is nothing surprising when the opinion of the experts diverge in any new field of research. After all, rogue waves may appear for a multiplicity of reasons and not necessarily only in optical fibers and not only in the process of supercontinuum generation. We know by now that rogue waves may be generated by lasers, appear in wide aperture cavities, in plasmas and in a variety of other optical systems. Theorists, in turn, have suggested many other situations when rogue waves may be observed. The strict definition of a rogue wave is still an open question. For example, it has been suggested that it is defined as ‘an optical pulse whose amplitude or intensity is much higher than that of the surrounding pulses’. This definition (as suggested by a peer reviewer) is clear at the intuitive level and can be easily extended to the case of spatial beams although additional clarifications are still needed. An extended definition has been presented earlier by N Akhmediev and E Pelinovsky (2010 Eur. Phys. J. Spec. Top. 185 1–4). Discussions along these lines are always useful and all new approaches stimulate research and encourage discoveries of new phenomena. Despite the potentially existing disagreements, the scientific terms ‘optical rogue waves’ and ‘extreme events’ do exist. Therefore coordination of our efforts in either unifying the concept or in introducing alternative definitions must be continued. From

  2. Analyses of Observed and Anticipated Changes in Extreme Climate Events in the Northwest Himalaya

    Directory of Open Access Journals (Sweden)

    Dharmaveer Singh

    2016-02-01

    Full Text Available In this study, past (1970-2005 as well as future long term (2011-2099 trends in various extreme events of temperature and precipitation have been investigated over selected hydro-meteorological stations in the Sutlej river basin. The ensembles of two Coupled Model Intercomparison Project (CMIP3 models: third generation Canadian Coupled Global Climate Model and Hadley Centre Coupled Model have been used for simulation of future daily time series of temperature (maximum and minimum and precipitation under A2 emission scenario. Large scale atmospheric variables of both models and National Centre for Environmental Prediction/National Centre for Atmospheric Research reanalysis data sets have been downscaled using statistical downscaling technique at individual stations. A total number of 25 extreme indices of temperature (14 and precipitation (11 as specified by the Expert Team of the World Meteorological Organization and Climate Variability and Predictability are derived for the past and future periods. Trends in extreme indices are detected over time using the modified Mann-Kendall test method. The stations which have shown either decrease or no change in hot extreme events (i.e., maximum TMax, warm days, warm nights, maximum TMin, tropical nights, summer days and warm spell duration indicators for 1970–2005 and increase in cold extreme events (cool days, cool nights, frost days and cold spell duration indicators are predicted to increase and decrease respectively in the future. In addition, an increase in frequency and intensity of extreme precipitation events is also predicted.

  3. Combined effects of extreme climatic events and elevation on nutritional quality and herbivory of Alpine plants.

    Directory of Open Access Journals (Sweden)

    Annette Leingärtner

    Full Text Available Climatic extreme events can cause the shift or disruption of plant-insect interactions due to altered plant quality, e.g. leaf carbon to nitrogen ratios, and phenology. However, the response of plant-herbivore interactions to extreme events and climatic gradients has been rarely studied, although climatic extremes will increase in frequency and intensity in the future and insect herbivores represent a highly diverse and functionally important group. We set up a replicated climate change experiment along elevational gradients in the German Alps to study the responses of three plant guilds and their herbivory by insects to extreme events (extreme drought, advanced and delayed snowmelt versus control plots under different climatic conditions on 15 grassland sites. Our results indicate that elevational shifts in CN (carbon to nitrogen ratios and herbivory depend on plant guild and season. CN ratios increased with altitude for grasses, but decreased for legumes and other forbs. In contrast to our hypotheses, extreme climatic events did not significantly affect CN ratios and herbivory. Thus, our study indicates that nutritional quality of plants and antagonistic interactions with insect herbivores are robust against seasonal climatic extremes. Across the three functional plant guilds, herbivory increased with nitrogen concentrations. Further, increased CN ratios indicate a reduction in nutritional plant quality with advancing season. Although our results revealed no direct effects of extreme climatic events, the opposing responses of plant guilds along elevation imply that competitive interactions within plant communities might change under future climates, with unknown consequences for plant-herbivore interactions and plant community composition.

  4. Quantifying Future Changes in Extreme Precipitation Events Based on Resolved Synoptic Atmospheric Patterns

    Science.gov (United States)

    Gao, X.; Schlosser, C. A.; Monier, E.; Entekhabi, D.

    2012-12-01

    An important question for climate change science is possible shifts in the extremes of regional water cycle, especially changes in patterns, intensity and/or frequency of extreme precipitation events. In this study, an analogue method is developed to help detect extreme precipitation events and their potential changes under future climate regimes without relying on the highly uncertain modeled precipitation. Our approach is based on the use of composite maps to identify the distinct synoptic and large-scale atmospheric conditions that lead to extreme precipitation events at local scales. The analysis of extreme daily precipitation events, exemplified in the south-central United States, is carried out using 62-yr (1948-2010) CPC gridded station data and NASA's Modern Era Retrospective-analysis for Research and Applications (MERRA). Various aspects of the daily extremes are examined, including their historical ranking, associated common circulation features at upper and lower levels of the atmosphere, and moisture plumes. The scheme is first evaluated for the multiple climate model simulations of the 20th century from Coupled Model Intercomparison Project Phase 5 (CMIP5) archive to determine whether the statistical nature of modeled precipitation events (i.e. the numbers of occurrences over each season) could well correspond to that of the observed. Further, the approach will be applied to the CMIP5 multi-model projections of various climate change scenarios (i.e. Representative Concentration Pathways (RCP) scenarios) in the next century to assess the potential changes in the probability of extreme precipitation events. The research results from this study should be of particular significance to help society develop adaptive strategies and prevent catastrophic losses.

  5. Changes in the frequency of extreme air pollution events over the Eastern United States and Europe

    Science.gov (United States)

    Rieder, H. E.; Fiore, A. M.; Polvani, L. M.; Lamarque, J.-F.; Fang, Y.; Staehelin, J.

    2012-04-01

    Over the past few decades, thresholds for national air quality standards, intended to protect public health and welfare, have been lowered repeatedly. At the same time observations, over Europe and the Eastern U.S., demonstrate that extreme air pollution events (high O3 and PM2.5) are typically associated with stagnation events. Recent work showed that in a changing climate high air pollution events are likely to increase in frequency and duration. Within this work we examine meteorological and surface ozone observations from CASTNet over the U.S. and EMEP over Europe. With innovative statistical tools - i.e., statistics of extremes (EVT) - we analyze the frequency distribution of extreme air pollution events over the Eastern United States and Europe. The upper tail of observed values at individual stations (e.g., within the CASTNet), i.e., the extremes (maximum daily 8-hour average (MDA8) O3>60ppb) are poorly described by a Gaussian distribution. However, further analysis showed that applying Peak-Over-Threshold-models, better capture the extremes and allows us to estimate return levels of pollution events above certain threshold values of interest. The results show that changes in national ambient air quality standards had significant effect on the occurrence frequency of high air pollution episodes.

  6. How well do CORDEX models simulate extreme rainfall events over the East Coast of South Africa?

    Science.gov (United States)

    Abba Omar, Sabina; Abiodun, Babatunde J.

    2016-01-01

    This study assesses the capability of regional climate models (RCMs) in simulating the characteristics of widespread extreme rainfall events over the East Coast of South Africa. Simulations of nine RCMs from the Coordinated Regional Downscaling Experiment (CORDEX) were analyzed for the study. All the simulations cover 12 years (1996-2008). Using the 95th percentile of daily rainfall as the threshold of extreme events and the simultaneous occurrence of extreme events over 50 % of the East Coast as widespread extreme events (WERE), we compared the characteristics of simulated WERE with observations (GPCP and TRMM) and with the reanalysis (ERAINT) that forced the simulations. Most RCMs perform well in simulating the seasonal variation of WEREs over the East Coast but perform poorly in simulating the interannual variability. Based on their rainfall synoptic patterns over Southern Africa, the WEREs in the East Coast can be generally classified into four groups. The first group connects the WEREs with tropical rainfall activities over the subcontinent. The second group links WEREs with frontal rainfall south of the subcontinent. The third group links the WEREs with both tropical and temperate rainfall activities while the fourth group represents isolated WEREs. The RCMs show different capabilities in simulating the frequency of WERE in each group, some perform better than ERAINT while some perform worse. Results of this study could provide information on the usability of RCMs in downscaling the impact of climate change on widespread extreme rainfall events over South Africa.

  7. Impact of extreme precipitation events in the Miño-Sil river basin

    Science.gov (United States)

    Fernández-González, Manuel; Añel, Juan Antonio; de la Torre, Laura

    2015-04-01

    We herein research the impact of extreme rainfall events in the Miño-Sil basin, a heavily dammed basin located in the northwestern Iberian Peninsula. Extreme rainfall events are very important in this basin because with 106 dams it is the most dammed in Spain. These dams are almost exclusively used for hydropower generation, the installed generating capacity reaches more than 2700 MW and represents almost 9% of the total installed electrical generation capacity of the Iberian Peninsula, therefore with a potential impact on the energy market. We research the extreme events of rainfall an their return periods trying to reproduce the past extreme events of rainfall and their time periods to prove the proper functioning of the adapted model, so we can forecast future extreme events of rainfall in the basin. This research tries to optimize the storage of dams and adapt the management to problems as climate change. The results obtained are very relevant for hydroelectric generation because the operation of hydropower system depends primarily on the availability of storaged water.

  8. Extreme weather events: Should drinking water quality management systems adapt to changing risk profiles?

    Science.gov (United States)

    Khan, Stuart J; Deere, Daniel; Leusch, Frederic D L; Humpage, Andrew; Jenkins, Madeleine; Cunliffe, David

    2015-11-15

    Among the most widely predicted and accepted consequences of global climate change are increases in both the frequency and severity of a variety of extreme weather events. Such weather events include heavy rainfall and floods, cyclones, droughts, heatwaves, extreme cold, and wildfires, each of which can potentially impact drinking water quality by affecting water catchments, storage reservoirs, the performance of water treatment processes or the integrity of distribution systems. Drinking water guidelines, such as the Australian Drinking Water Guidelines and the World Health Organization Guidelines for Drinking-water Quality, provide guidance for the safe management of drinking water. These documents present principles and strategies for managing risks that may be posed to drinking water quality. While these principles and strategies are applicable to all types of water quality risks, very little specific attention has been paid to the management of extreme weather events. We present a review of recent literature on water quality impacts of extreme weather events and consider practical opportunities for improved guidance for water managers. We conclude that there is a case for an enhanced focus on the management of water quality impacts from extreme weather events in future revisions of water quality guidance documents. PMID:26311274

  9. Recent changes in extreme rainfall events in Peninsular Malaysia: 1971-2005

    Science.gov (United States)

    Wan Zin, Wan Zawiah; Jamaludin, Suhaila; Deni, Sayang Mohd; Jemain, Abdul Aziz

    2009-05-01

    This paper assesses recent changes in extremes of annual rainfall in Peninsular Malaysia based on daily rainfall data for ten rain-gauged stations over the period 1971-2005. Eight indices that represent the extreme events are defined and analyzed. Maps of trends for these indices, which are extreme dry spell (XDS), extreme rain sum (XRS), extreme wet day intensities at 95% and 99% percentiles (I95 and I99), proportion of extreme wet day to the total wet day (R95 and R99), and frequency of extreme wet day at 95% and 99% percentiles (N95 and N99), were analyzed based on annual data and seasons. When the indices are evaluated annually, the Mann-Kendall and linear regression trend tests showed increasing trends in the extreme intensity indices (I95 and I99) at two stations. A significant decrease in N99, associated with the frequency of extremely wet days, was observed at 60% of the stations. The change points for these indices are found to occur in the period of the 1980s. There is no significant trend detected for XDS, XRS, and proportion of extreme rainfall over total rainfall amount indices during the period considered in this study. Descriptive analysis of indices during the monsoon period showed that the annual spatial pattern for the peninsula is very much influenced by the northeast monsoon where the highest mean values for majority of the indices occur during this time period.

  10. Potential impacts of afforestation on climate change and extreme events in Nigeria

    Science.gov (United States)

    Abiodun, Babatunde J.; Salami, Ayobami T.; Matthew, Olaniran J.; Odedokun, Sola

    2013-07-01

    Afforestation is usually thought as a good approach to mitigate impacts of warming over a region. This study presents an argument that afforestation may have bigger impacts than originally thought by previous studies. The study investigates the impacts of afforestation on future climate and extreme events in Nigeria, using a regional climate model (RegCM3), forced with global climate model simulations. The impacts of seven afforestation options on the near future (2031-2050, under A1B scenario) climate and the extreme events are investigated. RegCM3 replicates essential features in the present-day (1981-2000) climate and the associated extreme events, and adequately simulates the seasonal variations over the ecological zones in the country. However, the model simulates the seasonal climate better over the northern ecological zones than over the southern ecological zones. The simulated spatial distribution of the extreme events agrees well with the observation, though the magnitude of the simulated events is smaller than the observed. The study shows that afforestation in Nigeria could have both positive and negative future impacts on the climate change and extreme events in the country. While afforestation reduces the projected global warming and enhances rainfall over the afforested area (and over coastal zones), it enhances the warming and reduces the rainfall over the north-eastern part of the country. In addition, the afforestation induces more frequent occurrence of extreme rainfall events (flooding) over the coastal region and more frequent occurrence of heat waves and droughts over the semi-arid region. The positive and negative impacts of the afforestation are not limited to Nigeria; they extend to the neighboring countries. While afforestation lowers the warming and enhances rainfall over Benin Republic, it increases the warming and lowers the rainfall over Niger, Chad and Cameroon. The result of the study has important implication for the ongoing climate

  11. Vb-type cyclones and their role in extreme precipitation events in Central Europe

    Science.gov (United States)

    Messmer, Martina; José Gómez-Navarro, Juan; Raible, Christoph C.

    2015-04-01

    Extreme weather situations are of major relevance for society, since they lead to great economical and personal damage. In Central Europe, one important source of extreme precipitation accompanied by large flooding events is the so-called Vb-event, classified by W. J. Van Bebber in 1891. Vb-events are defined as cyclones developing over the western Mediterranean that move north eastward. They can uptake large amounts of moisture, which is then transported towards the Alps and Central Europe, inducing heavy precipitation and flooding events. Despite their importance the relevant processes triggering Vb-events and their impact in extreme precipitation are not yet fully understood. The overall goal of this study research is to understand the dynamics of the past events and to provide a reliable climatology, which would provide a first guess for future behaviour of these potentially disastrous situations. A cyclone detection and tracking tool is applied to ERA Interim reanalysis (1979-2013) in order to identify the most prominent Vb-situations. Vb-events are detected and tracked in the geopotential height at 850 hPa. Subsequently, the cyclones are automatically filtered with criteria based on the origin and end of the track, which allows us discarding those paths that should not be considered as Vb-events. Precipitation in the ERA Interim and E-OBS database is used to evaluate the precipitation amounts corresponding to each case and to assess the consistency between datasets. ERA Interim and E-OBS data consistently indicate that there is great variability in precipitation amounts within different Vb-events. While it is expected that Vb-events are associated with extreme precipitation, this is only true for about one quarter of all cases. Nevertheless around 15% of extreme precipitation days (99 percentile) over the Alpine region are triggered by Vb-events. In order to obtain a better understanding of the large variability in Vb-events, the ten heaviest and lowest

  12. Extreme precipitation events and increased risk of campylobacteriosis in Maryland, U.S.A.

    Science.gov (United States)

    Soneja, Sutyajeet; Jiang, Chengsheng; Romeo Upperman, Crystal; Murtugudde, Raghu; S Mitchell, Clifford; Blythe, David; Sapkota, Amy R; Sapkota, Amir

    2016-08-01

    Consumption of contaminated poultry, raw milk and water are significant risk factors for Campylobacter infection. Previous studies also have investigated the association between weather (temperature and precipitation) and increased risk of campylobacteriosis, but limited information exists regarding the impacts of extreme heat and precipitation events on campylobacteriosis risk, and how such risk may differentially impact coastal communities. We obtained Campylobacter case data 2002-2012; n=4804) from the Maryland Foodborne Diseases Active Surveillance Network (FoodNet). We identified extreme heat and extreme precipitation events during this time (2002-2012) using location and calendar day specific thresholds (95th percentile for extreme heat and 90th percentile for extreme precipitation) that were computed based on a 30-year baseline (1960-1989). We linked these datasets using GIS and used negative binomial generalized estimating equations adjusted for demographic confounders to calculate the association between exposure to extreme events and risk of campylobacteriosis in Maryland. We observed that a one-day increase in exposure to extreme precipitation events was associated with a 3% increase in risk of campylobacteriosis in coastal areas of Maryland (Incidence Rate Ratio (IRR): 1.03, 95% confidence interval (CI): 1.01, 1.05), but such an association was not observed in noncoastal areas. Furthermore, the risk associated with extreme precipitation events was considerably higher during La Niña periods (IRR: 1.09, 95% CI: 1.05, 1.13), while there was no evidence of elevated risk during El Niño or ENSO Neutral periods. Exposure to extreme heat events was not associated with an increased risk of campylobacteriosis, except during La Niña periods (IRR: 1.04, 95% CI: 1.01, 1.08). Extreme precipitation events could result in flooding within coastal areas that may bring water contaminated with bacterial pathogens (originating from sources such as septic systems

  13. An evaluation of extreme temperature events in Spain based on process control charts

    Science.gov (United States)

    Villeta, Maria; Valencia, Jose Luis; Saa, Antonio; Tarquis, Ana Maria

    2014-05-01

    In recent decades, extreme climate events have attracted the attention of growing number of researchers due to the fact these events cause large costs in agriculture and its insurance planning associated. This work focuses in extreme temperature events in concrete, and offers an analysis of them based on statistical process control tools, which are unusual in climate studios. Throughout this work we have evaluated the maximum and minimum temperatures for geographical areas of a Spanish region over a period from last century, in order to test statistically whether there is evidence of an increase of extreme temperature events, by applying methods of statistical process control. To this end, the temperature series have been seasonally adjusted. The analysis was performed on the anomalies temperatures series. For each of the geographic areas under study, statistical control charts for attributes were obtained for both maximum and minimum annual anomalies. Once the specification limits have been determined, they have been used for classifying observations as extreme or normal. This allows drawing a general assessment of the tendencies of extreme temperature events in the analyzed region. It can be concluded that there are three different cycles in maximum annual temperatures in all geographical areas analyzed: a first cycle, in which the proportion of extremes temperature days remain stable; a second period in which the proportion of the extremes days fallen slightly from the early years of the series; and a third stage, in which the proportion of days with extreme high temperatures increases significantly with respect to that observed in previous periods. With respect to minimum extreme annual temperatures in the Spanish region evaluated, another three cycles can be observed in all geographical areas: a first cycle from the start of the series, in which the proportion of extreme minimum temperature days remains stable; a second cycle in which the proportion of extreme

  14. A spatial and nonstationary model for the frequency of extreme rainfall events

    DEFF Research Database (Denmark)

    Gregersen, Ida Bülow; Madsen, Henrik; Rosbjerg, Dan;

    2013-01-01

    Changes in the properties of extreme rainfall events have been observed worldwide. In relation to the discussion of ongoing climatic changes, it is of high importance to attribute these changes to known sources of climate variability. Focusing on spatial and temporal changes in the frequency of......, and the average summer temperature. The two latter showed a high relative importance. The established link will be beneficial when predicting future occurrences of precipitation extremes. © 2013. American Geophysical Union. All Rights Reserved....

  15. Beyond Gaussian averages: redirecting international business and management research toward extreme events and power laws

    OpenAIRE

    Pierpaolo Andriani; Bill McKelvey

    2007-01-01

    Practicing managers live in a world of ‘extremes’, but international business and management research is based on Gaussian statistics that rule out such extremes. On occasion, positive feedback processes among interactive data points cause extreme events characterized by power laws. They seem ubiquitous; we list 80 kinds of them – half each among natural and social phenomena. We use imposed tension and Per Bak's ‘self-organized criticality’ to argue that Pareto-based science and statistics (b...

  16. 500 years of regional forest growth variability and links to climatic extreme events in Europe

    OpenAIRE

    Babst, Flurin; Carrer, Marco; Poulter, Benjamin; Urbinati, Carlo; Neuwirth, Burkhard; Frank, David

    2012-01-01

    Climatic extreme events strongly affect forest growth and thus significantly influence the inter-annual terrestrial carbon balance. As we are facing an increase in frequency and intensity of climate extremes, extensive empirical archives are required to assess continental scale impacts of temperature and precipitation anomalies. Here we divide a tree-ring network of approximately 1000 sites into fifteen groups of similar high-frequency growth variability to reconstruct regional positive and n...

  17. Trend in frequency of extreme precipitation events over Ontario from ensembles of multiple GCMs

    Science.gov (United States)

    Deng, Ziwang; Qiu, Xin; Liu, Jinliang; Madras, Neal; Wang, Xiaogang; Zhu, Huaiping

    2016-05-01

    As one of the most important extreme weather event types, extreme precipitation events have significant impacts on human and natural environment. This study assesses the projected long term trends in frequency of occurrence of extreme precipitation events represented by heavy precipitation days, very heavy precipitation days, very wet days and extreme wet days over Ontario, based on results of 21 CMIP3 GCM runs. To achieve this goal, first, all model data are linearly interpolated onto 682 grid points (0.45° × 0.45°) in Ontario; Next, biases in model daily precipitation amount are corrected with a local intensity scaling method to make the total wet days and total wet day precipitation from each of the GCMs are consistent with that from the climate forecast system reanalysis data, and then the four indices are estimated for each of the 21 GCM runs for 1968-2000, 2046-2065 and 2081-2100. After that, with the assumption that the rate parameter of the Poisson process for the occurrence of extreme precipitation events may vary with time as climate changes, the Poisson regression model which expresses the log rate as a linear function of time is used to detect the trend in frequency of extreme events in the GCMs simulations; Finally, the trends and their uncertainty are estimated. The result shows that in the twenty-first century annual heavy precipitation days, very heavy precipitation days and very wet days and extreme wet days are likely to significantly increase over major parts of Ontario and particularly heavy precipitation days, very wet days are very likely to significantly increase in some sub-regions in eastern Ontario. However, trends of seasonal indices are not significant.

  18. Exploring the Terrestrial Ecosystem Response to Extreme Weather Events using Multiple Land Surface Models

    Science.gov (United States)

    Xu, L.; Schlosser, C. A.; Kicklighter, D. W.; Felzer, B. S.; Monier, E.; Paw U, K.

    2012-12-01

    This study investigates the complex terrestrial ecosystems response to extreme weather events using three different land surface models. Previous studies have showed that extreme weather events can have serious and damaging impacts on human and natural systems and they are most evident on regional and local scales. Under climate change, extreme weather events are likely to increase in both magnitude and frequency, making realistic simulation of ecosystems response to extreme events more essential than ever in assessing the potential damaging impacts. Three different land surface models are used to explore the impacts of extreme events on regional to continental ecosystem responses. The Terrestrial Ecosystem Model (TEM) is a process-based ecosystem model that uses spatially referenced information on climate, elevation, soils, vegetation and water availability to make monthly estimates of vegetation and soil carbon and nitrogen fluxes and pool sizes. The Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) is a multi-layered land surface model based on eddy-covariance theory to calculate the biosphere-atmosphere exchanges of carbon dioxide, water, and momentums. The Community Land Model (CLM) is a community-based model widely used in global-scale land data assimilation research. The study focuses on the complex interactions and feedbacks between the terrestrial ecosystem and the atmosphere such as water cycle, carbon and nitrogen budgets, and environmental conditions. The model simulations and performances are evaluated using the biogeophysical and micrometeorological observation data from the AmeriFlux sites across the continental US. This study compares and evaluates the ability of different models and their key components to capture terrestrial response to extreme weather events.

  19. Estimating the impact of extreme climatic events on riverine sediment transport: new tools and methods

    Science.gov (United States)

    Lajeunesse, E.; Delacourt, C.; Allemand, P.; Limare, A.; Dessert, C.; Ammann, J.; Grandjean, P.

    2010-12-01

    A series of recent works have underlined that the flux of material exported outside of a watershed is dramatically increased during extreme climatic events, such as storms, tropical cyclones and hurricanes [Dadson et al., 2003 and 2004; Hilton et al., 2008]. Indeed the exceptionally high rainfall rates reached during these events trigger runoff and landsliding which destabilize slopes and accumulate a significant amount of sediments in flooded rivers. This observation raises the question of the control that extreme climatic events might exert on the denudation rate and the morphology of watersheds. Addressing this questions requires to measure sediment transport in flooded rivers. However most conventional sediment monitoring technics rely on manned operated measurements which cannot be performed during extreme climatic events. Monitoring riverine sediment transport during extreme climatic events remains therefore a challenging issue because of the lack of instruments and methodologies adapted to such extreme conditions. In this paper, we present a new methodology aimed at estimating the impact of extreme events on sediment transport in rivers. Our approach relies on the development of two instruments. The first one is an in-situ optical instrument, based on a LISST-25X sensor, capable of measuring both the water level and the concentration of suspended matter in rivers with a time step going from one measurement every hour at low flow to one measurement every 2 minutes during a flood. The second instrument is a remote controlled drone helicopter used to acquire high resolution stereophotogrammetric images of river beds used to compute DEMs and to estimate how flash floods impact the granulometry and the morphology of the river. These two instruments were developed and tested during a 1.5 years field survey performed from june 2007 to january 2009 on the Capesterre river located on Basse-Terre island (Guadeloupe archipelago, Lesser Antilles Arc).

  20. Investigating the variation and non-stationarity in precipitation extremes based on the concept of event-based extreme precipitation

    Science.gov (United States)

    She, Dunxian; Shao, Quanxi; Xia, Jun; Taylor, John A.; Zhang, Yongyong; Zhang, Liping; Zhang, Xiang; Zou, Lei

    2015-11-01

    Extreme precipitations (EP) could induce a series of social, environmental and ecological problems. Traditional EP analysis usually investigated the characteristics based on a fixed time scale and therefore ignored the continuity of EP occurrence. As a result, a comprehensive assessment on the influence and consequence of the EP occurring during consecutive time periods were largely eliminated. On the other hand, the characteristics of EP, including variables such as frequency, intensity and extreme volume, were commonly defined without sufficient consideration of the local tolerance capacity (which can be represented by a threshold level of EP) and therefore would sometimes be inappropriate. In this study, we proposed a concept of event-based extreme precipitation (EEP) by considering the continuity of EP and defined the statistical variables for the characteristics of an EEP event by taking account of local tolerance capacity. An EEP was identified as a collection of precipitation data over the consecutive time period in which all the precipitation amounts are above the pre-defined threshold, and EEP events are separated by at least one time step (e.g., day or hour) with precipitation amount below the threshold. As a case study which in fact motivated our proposal, we investigated the changes and variations of EEP with the consideration of potential non-stationarity in the Hanjiang River Basin of China (HJRB) during the time period of 1960-2013. Results showed that the concept of EEP, which could reflect the impact of continuity of EP occurrence and mirror the differences of local tolerance capacity, was more appropriate than the traditional method in the EP analysis.

  1. Extreme Events in China under Climate Change: Uncertainty and related impacts (CSSP-FOREX)

    Science.gov (United States)

    Leckebusch, Gregor C.; Befort, Daniel J.; Hodges, Kevin I.

    2016-04-01

    Suitable adaptation strategies or the timely initiation of related mitigation efforts in East Asia will strongly depend on robust and comprehensive information about future near-term as well as long-term potential changes in the climate system. Therefore, understanding the driving mechanisms associated with the East Asian climate is of major importance. The FOREX project (Fostering Regional Decision Making by the Assessment of Uncertainties of Future Regional Extremes and their Linkage to Global Climate System Variability for China and East Asia) focuses on the investigation of extreme wind and rainfall related events over Eastern Asia and their possible future changes. Here, analyses focus on the link between local extreme events and their driving weather systems. This includes the coupling between local rainfall extremes and tropical cyclones, the Meiyu frontal system, extra-tropical teleconnections and monsoonal activity. Furthermore, the relation between these driving weather systems and large-scale variability modes, e.g. NAO, PDO, ENSO is analysed. Thus, beside analysing future changes of local extreme events, the temporal variability of their driving weather systems and related large-scale variability modes will be assessed in current CMIP5 global model simulations to obtain more robust results. Beyond an overview of FOREX itself, first results regarding the link between local extremes and their steering weather systems based on observational and reanalysis data are shown. Special focus is laid on the contribution of monsoonal activity, tropical cyclones and the Meiyu frontal system on the inter-annual variability of the East Asian summer rainfall.

  2. Extreme climatic events in relation to global change and their impact on life histories

    Directory of Open Access Journals (Sweden)

    Juan MORENO, Anders Pape Møller

    2011-06-01

    Full Text Available Extreme weather conditions occur at an increasing rate as evidenced by higher frequency of hurricanes and more extreme precipitation and temperature anomalies. Such extreme environmental conditions will have important implications for all living organisms through greater frequency of reproductive failure and reduced adult survival. We review examples of reproductive failure and reduced survival related to extreme weather conditions. Phenotypic plasticity may not be sufficient to allow adaptation to extreme weather for many animals. Theory predicts reduced reproductive effort as a response to increased stochasticity. We predict that patterns of natural selection will change towards truncation selection as environmental conditions become more extreme. Such changes in patterns of selection may facilitate adaptation to extreme events. However, effects of selection on reproductive effort are difficult to detect. We present a number of predictions for the effects of extreme weather conditions in need of empirical tests. Finally, we suggest a number of empirical reviews that could improve our ability to judge the effects of extreme environmental conditions on life history [Current Zoology 57 (3: 375–389, 2011].

  3. Extreme climatic events in relation to global change and their impact on life histories

    Institute of Scientific and Technical Information of China (English)

    Juan MORENO; Anders Pape Mφller

    2011-01-01

    Extreme weather conditions occur at an increasing rate as evidenced by higher frequency of hurricanes and more extreme precipitation and temperature anomalies. Such extreme environmental conditions will have important implications for all living organisms through greater frequency of reproductive failure and reduced adult survival. We review examples of reproductive failure and reduced survival related to extreme weather conditions. Phenotypic plasticity may not be sufficient to allow adaptation to extreme weather for many animals. Theory predicts reduced reproductive effort as a response to increased stochasticity. We predict that patterns of natural selection will change towards truncation selection as environmental conditions become more extreme. Such changes in patterns of selection may facilitate adaptation to extreme events. However, effects of selection on reproductive effort are difficult to detect. We present a number of predictions for the effects of extreme weather conditions in need of empirical tests. Finally, we suggest a number of empirical reviews that could improve our ability to judge the effects of extreme environmental conditions on life history.

  4. 500 years of regional forest growth variability and links to climatic extreme events in Europe

    International Nuclear Information System (INIS)

    Climatic extreme events strongly affect forest growth and thus significantly influence the inter-annual terrestrial carbon balance. As we are facing an increase in frequency and intensity of climate extremes, extensive empirical archives are required to assess continental scale impacts of temperature and precipitation anomalies. Here we divide a tree-ring network of approximately 1000 sites into fifteen groups of similar high-frequency growth variability to reconstruct regional positive and negative extreme events in different parts of Europe between 1500 and 2008. Synchronized growth maxima or minima within and among regions indicate eighteen years in the pre-instrumental period and two events in the 20th century (1948, 1976) with extensive radial growth fluctuations. Comparisons with instrumental data showed that the European tree-ring network mirrors the spatial extent of temperature and precipitation extremes, but the interpretation of pre-instrumental events is challenged by lagged responses to off-growing season climate extremes. We were able to attribute growth minima in subsequent years to unfavourable August–October conditions and to mild climate during winter months associated with respiratory carbon losses. Our results emphasize the importance of carry-over effects and species-specific growth characteristics for forest productivity. Furthermore, they promote the use of regional tree-ring chronologies in research related to climate variability and terrestrial carbon sink dynamics. (letter)

  5. Introduction to CHRS CONNECT - a global extreme precipitation event database using object-oriented approach

    Science.gov (United States)

    Nguyen, P.; Thorstensen, A. R.; Liu, H.; Sellars, S. L.; Ashouri, H.; Huynh, P.; Palacios, T.; Li, P.; Tran, H.; Braithwaite, D.; Hsu, K. L.; Gao, X.; Sorooshian, S.

    2015-12-01

    Extreme precipitation events cause natural disasters that impact many parts of the world. Understanding how these events vary in space and time is a key goal in climatology research. The recently developed CHRS CONNECT (Center for Hydrometeorology & Remote Sensing CONNected precipitation objECT) system is a global extreme precipitation event database derived from CHRS's satellite precipitation data products, including PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) and PERSIANN-CDR (Climate Data Record). Precipitation data from PERSIANN is hourly, 0.25ox0.25o grid, 60oS - 60oN, from 2000 to 2015, and data from PERSIANN-CDR is daily, 0.25ox0.25o grid, 60oS - 60oN, from 1983 to 2015. We used an advanced method in computer science which represents a data point on a three dimensional grid (longitude, latitude and time) called volumetric pixel or voxel. An object segmentation algorithm was developed to derive precipitation events as objects. In each object, voxels are connected to each other through the 26 connectivity faces (a voxel is connected to a neighboring voxel if they share a common face). The object-oriented algorithm was designed to provide a unique means in which extreme precipitation events and their attributes can be stored in a searchable database. This database is accessible through a user-friendly interface (connect.eng.uci.edu), allowing the user to retrieve events that fit specific criteria of interest such as spatiotemporal domain, maximum intensity, minimum duration and climatology indices. The interface includes several modes for visualization such as total precipitation, event tracking, and event evolution animation. The CHRS CONNECT tool is designed to be used for climatology research related to extreme precipitation events as well as for water resources management applications.

  6. Climate Change, Extreme Weather Events, and Human Health Implications in the Asia Pacific Region.

    Science.gov (United States)

    Hashim, Jamal Hisham; Hashim, Zailina

    2016-03-01

    The Asia Pacific region is regarded as the most disaster-prone area of the world. Since 2000, 1.2 billion people have been exposed to hydrometeorological hazards alone through 1215 disaster events. The impacts of climate change on meteorological phenomena and environmental consequences are well documented. However, the impacts on health are more elusive. Nevertheless, climate change is believed to alter weather patterns on the regional scale, giving rise to extreme weather events. The impacts from extreme weather events are definitely more acute and traumatic in nature, leading to deaths and injuries, as well as debilitating and fatal communicable diseases. Extreme weather events include heat waves, cold waves, floods, droughts, hurricanes, tropical cyclones, heavy rain, and snowfalls. Globally, within the 20-year period from 1993 to 2012, more than 530 000 people died as a direct result of almost 15 000 extreme weather events, with losses of more than US$2.5 trillion in purchasing power parity. PMID:26377857

  7. On Predictive Understanding of Extreme Events: Pattern Recognition Approach; Prediction Algorithms; Applications to Disaster Preparedness

    Science.gov (United States)

    Keilis-Borok, V. I.; Soloviev, A.; Gabrielov, A.

    2011-12-01

    We describe a uniform approach to predicting different extreme events, also known as critical phenomena, disasters, or crises. The following types of such events are considered: strong earthquakes; economic recessions (their onset and termination); surges of unemployment; surges of crime; and electoral changes of the governing party. A uniform approach is possible due to the common feature of these events: each of them is generated by a certain hierarchical dissipative complex system. After a coarse-graining, such systems exhibit regular behavior patterns; we look among them for "premonitory patterns" that signal the approach of an extreme event. We introduce methodology, based on the optimal control theory, assisting disaster management in choosing optimal set of disaster preparedness measures undertaken in response to a prediction. Predictions with their currently realistic (limited) accuracy do allow preventing a considerable part of the damage by a hierarchy of preparedness measures. Accuracy of prediction should be known, but not necessarily high.

  8. Simulation of the catastrophic floods caused by extreme rainfall events - Uh River basin case study

    OpenAIRE

    Pekárová, Pavla; Halmová, Dana; Mitková, Veronika

    2005-01-01

    The extreme rainfall events in Central and East Europe on August 2002 rise the question, how other basins would respond on such rainfall situations. Such theorisation helps us to arrange in advance the necessary activity in the basin to reduce the consequence of the assumed disaster. The aim of the study is to recognise a reaction of the Uh River basin (Slovakia, Ukraine) to the simulated catastrophic rainfall events from August 2002. Two precipitation scenarios, sc1 and sc2, were created. Th...

  9. The effects of climatic fluctuations and extreme events on running water ecosystems

    OpenAIRE

    Woodward, Guy; Bonada, Núria; Lee. E. Brown; Russell G. DEATH; Durance, Isabelle; Gray, Clare; Hladyz, Sally; Ledger, Mark E.; Milner, Alexander M.; Ormerod, Steve J.; Thompson, Ross M.; Pawar, Samraat

    2016-01-01

    Most research on the effects of environmental change in freshwaters has focused on incremental changes in average conditions, rather than fluctuations or extreme events such as heatwaves, cold snaps, droughts, floods or wildfires, which may have even more profound consequences. Such events are commonly predicted to increase in frequency, intensity and duration with global climate change, with many systems being exposed to conditions with no recent historical precedent. We propose a mechanisti...

  10. Radiation doses along selected flight profiles during two extreme solar cosmic ray events

    OpenAIRE

    E. Flückiger; Bütikofer, R.

    2011-01-01

    The radiation dose rates at flight altitudes may be hazardously increased during solar cosmic ray events. Within the scope of this paper we investigate the total accumulated radiation doses, i.e. the contribution of galactic and solar cosmic rays, during the two extreme solar cosmic ray events on 29 September 1989 and on 20 January 2005 along selected flight profiles. In addition, the paper discusses the consequences of possible solar cosmic ray flux approximations on the results of the radia...

  11. Symptom attribution and presentation in general practice after an extreme life event

    OpenAIRE

    Nijrolder, I.; van der Velden, P.G.; Grievink, L.; Yzermans, J.

    2011-01-01

    Background. A serious life event is likely to shape attributions relating to symptoms experienced afterwards. While they may play an important role in prognosis and seeking care, such perceptions have hardly been studied among survivors of a disaster. Objective. To investigate the association between self-reported health problems that have been attributed to an extreme life event and the symptoms presented to GPs. Methods. A two-wave longitudinal survey (2–3 weeks and 18 months) among survivo...

  12. Extreme events, trends, and variability in Northern Hemisphere lake-ice phenology (1855-2005)

    Science.gov (United States)

    Benson, Barbara J.; Magnuson, John J.; Jensen, Olaf P.; Card, Virginia M.; Hodgkins, Glenn; Korhonen, Johanna; Livingstone, David M.; Stewart, Kenton M.; Weyhenmeyer, Gesa A.; Granin, Nick G.

    2012-01-01

    Often extreme events, more than changes in mean conditions, have the greatest impact on the environment and human well-being. Here we examine changes in the occurrence of extremes in the timing of the annual formation and disappearance of lake ice in the Northern Hemisphere. Both changes in the mean condition and in variability around the mean condition can alter the probability of extreme events. Using long-term ice phenology data covering two periods 1855–6 to 2004–5 and 1905–6 to 2004–5 for a total of 75 lakes, we examined patterns in long-term trends and variability in the context of understanding the occurrence of extreme events. We also examined patterns in trends for a 30-year subset (1975–6 to 2004–5) of the 100-year data set. Trends for ice variables in the recent 30-year period were steeper than those in the 100- and 150-year periods, and trends in the 150-year period were steeper than in the 100-year period. Ranges of rates of change (days per decade) among time periods based on linear regression were 0.3−1.6 later for freeze, 0.5−1.9 earlier for breakup, and 0.7−4.3 shorter for duration. Mostly, standard deviation did not change, or it decreased in the 150-year and 100-year periods. During the recent 50-year period, standard deviation calculated in 10-year windows increased for all ice measures. For the 150-year and 100-year periods changes in the mean ice dates rather than changes in variability most strongly influenced the significant increases in the frequency of extreme lake ice events associated with warmer conditions and decreases in the frequency of extreme events associated with cooler conditions.

  13. BOLIVAR-tool for analysis and simulation of metocean extreme events

    Science.gov (United States)

    Lopatoukhin, Leonid; Boukhanovsky, Alexander

    2015-04-01

    Metocean extreme events are caused by the combination of multivariate and multiscale processes which depend from each other in different scales (due to short-term, synoptic, annual, year-to-year variability). There is no simple method for their estimation with controllable tolerance. Thus, the extreme analysis in practice is sometimes reduced to the exploration of various methods and models in respect to decreasing the uncertainty of estimates. Therefore, a researcher needs the multifaceted computational tools which cover the various branches of extreme analysis. BOLIVAR is the multi-functional computational software for the researches and engineers who explore the extreme environmental conditions to design and build offshore structures and floating objects. It contains a set of computational modules of various methods for extreme analysis, and a set of modules for the stochastic and hydrodynamic simulation of metocean processes. In this sense BOLIVAR is a Problem Solving Environment (PSE). The BOLIVAR is designed for extreme events analysis and contains a set of computational modules of IDM, AMS, POT, MENU, and SINTEF methods, and a set of modules for stochastic simulation of metocean processes in various scales. The BOLIVAR is the tool to simplify the resource-consuming computational experiments to explore the metocean extremes in univariate and multivariate cases. There are field ARMA models for short-term variability, spatial-temporal random pulse model for synoptic variability (storms and calms alteration), cyclostationare model of annual and year-to-year variability. The combination of above mentioned modules and data sources allows to estimate: omnidirectional and directional extremes (with T-years return periods); multivariate extremes (the set of parameters) and evaluation of their impacts to marine structures and floating objects; extremes of spatial-temporal fields (including the trajectory of T-years storms). An employment of concurrent methods for

  14. Local instability driving extreme events in a pair of coupled chaotic electronic circuits.

    Science.gov (United States)

    de Oliveira, Gilson F; Di Lorenzo, Orlando; de Silans, Thierry Passerat; Chevrollier, Martine; Oriá, Marcos; Cavalcante, Hugo L D de Souza

    2016-06-01

    For a long time, extreme events happening in complex systems, such as financial markets, earthquakes, and neurological networks, were thought to follow power-law size distributions. More recently, evidence suggests that in many systems the largest and rarest events differ from the other ones. They are dragon kings, outliers that make the distribution deviate from a power law in the tail. Understanding the processes of formation of extreme events and what circumstances lead to dragon kings or to a power-law distribution is an open question and it is a very important one to assess whether extreme events will occur too often in a specific system. In the particular system studied in this paper, we show that the rate of occurrence of dragon kings is controlled by the value of a parameter. The system under study here is composed of two nearly identical chaotic oscillators which fail to remain in a permanently synchronized state when coupled. We analyze the statistics of the desynchronization events in this specific example of two coupled chaotic electronic circuits and find that modifying a parameter associated to the local instability responsible for the loss of synchronization reduces the occurrence of dragon kings, while preserving the power-law distribution of small- to intermediate-size events with the same scaling exponent. Our results support the hypothesis that the dragon kings are caused by local instabilities in the phase space. PMID:27415257

  15. Attribution of extreme weather and climate events overestimated by unreliable climate simulations

    Science.gov (United States)

    Bellprat, Omar; Doblas-Reyes, Francisco

    2016-03-01

    Event attribution aims to estimate the role of an external driver after the occurrence of an extreme weather and climate event by comparing the probability that the event occurs in two counterfactual worlds. These probabilities are typically computed using ensembles of climate simulations whose simulated probabilities are known to be imperfect. The implications of using imperfect models in this context are largely unknown, limited by the number of observed extreme events in the past to conduct a robust evaluation. Using an idealized framework, this model limitation is studied by generating large number of simulations with variable reliability in simulated probability. The framework illustrates that unreliable climate simulations are prone to overestimate the attributable risk to climate change. Climate model ensembles tend to be overconfident in their representation of the climate variability which leads to systematic increase in the attributable risk to an extreme event. Our results suggest that event attribution approaches comprising of a single climate model would benefit from ensemble calibration in order to account for model inadequacies similarly as operational forecasting systems.

  16. Local instability driving extreme events in a pair of coupled chaotic electronic circuits

    Science.gov (United States)

    de Oliveira, Gilson F.; Di Lorenzo, Orlando; de Silans, Thierry Passerat; Chevrollier, Martine; Oriá, Marcos; Cavalcante, Hugo L. D. de Souza

    2016-06-01

    For a long time, extreme events happening in complex systems, such as financial markets, earthquakes, and neurological networks, were thought to follow power-law size distributions. More recently, evidence suggests that in many systems the largest and rarest events differ from the other ones. They are dragon kings, outliers that make the distribution deviate from a power law in the tail. Understanding the processes of formation of extreme events and what circumstances lead to dragon kings or to a power-law distribution is an open question and it is a very important one to assess whether extreme events will occur too often in a specific system. In the particular system studied in this paper, we show that the rate of occurrence of dragon kings is controlled by the value of a parameter. The system under study here is composed of two nearly identical chaotic oscillators which fail to remain in a permanently synchronized state when coupled. We analyze the statistics of the desynchronization events in this specific example of two coupled chaotic electronic circuits and find that modifying a parameter associated to the local instability responsible for the loss of synchronization reduces the occurrence of dragon kings, while preserving the power-law distribution of small- to intermediate-size events with the same scaling exponent. Our results support the hypothesis that the dragon kings are caused by local instabilities in the phase space.

  17. Linking extreme climate events and economic impacts: Examples from the Swiss Alps

    International Nuclear Information System (INIS)

    This paper focuses upon topics related to current and possible future extreme weather events in order to highlight the links between climatic change and its economic impacts. Most of the examples given here are drawn from observations in Switzerland and the Alpine region that have a wealth of climatic, environmental and socio-economic data. These enable detailed studies to be undertaken on trends in mean and extreme climates and their impacts. Model simulations for a ''greenhouse climate'' suggest that risks associated with various forms of extreme events that affect the Alps may increase in the future, which could lead to high damage costs. In addition to the direct impacts of extremes, it is also necessary to take into account the increasing economic value of infrastructure located in zones potentially at risk. The final part of the paper addresses some of the issues that are related to fully integrated modeling approaches that are aimed at assessing the costs of damage in the wake of an extreme event. (author)

  18. Linking extreme climate events and economic impacts: Examples from the Swiss Alps

    International Nuclear Information System (INIS)

    This paper focuses upon topics related to current and possible future extreme weather events in order to highlight the links between climatic change and its economic impacts. Most of the examples given here are drawn from observations in Switzerland and the Alpine region that have a wealth of climatic, environmental and socio-economic data. These enable detailed studies to be undertaken on trends in mean and extreme climates and their impacts. Model simulations for a 'greenhouse climate' suggest that risks associated with various forms of extreme events that affect the Alps may increase in the future, which could lead to high damage costs. In addition to the direct impacts of extremes, it is also necessary to take into account the increasing economic value of infrastructure located in zones potentially at risk. The final part of the paper addresses some of the issues that are related to fully integrated modeling approaches that are aimed at assessing the costs of damage in the wake of an extreme event

  19. Changes in Extreme Events: from GCM Output to Social, Economic and Ecological Impacts

    Science.gov (United States)

    Tebaldi, C.; Meehl, G. A.

    2006-12-01

    Extreme events can deeply affect social and natural systems. The current generation of global climate model is producing information that can be directly used to characterize future changes in extreme events, and through a further step their impacts, despite their still relatively coarse resolution. It is important to define extreme indicators consistently with what we expect GCM to be able to represent reliably. We use two examples from our work, heat waves and frost days, that well describe different aspects of the analysis of extremes from GCM output. Frost days are "mild extremes" and their definition and computation is straightforward. GCMs can represent them accurately and display a strong consistent signal of change. The impacts of these changes will be extremely relevant for ecosystems and agriculture. Heat waves do not have a standard definition. On the basis of historical episodes we isolate characteristics that were responsible for the worst effects on human health, for example, and analyze these characteristics in model simulations, validating the model's historical simulations. The changes in these characteristics can then be easily translated in expected differential impacts on public health. Work in progress goes in the direction of better characterization of "heat waves" taking into account jointly a set of variables like maximum and minimum temperatures and humidity, better addressing the biological vulnerabilities of the populations at risk.

  20. Changes in Climate Extremes and Catastrophic Events in the Mongolian Plateau from 1951 to 2012

    DEFF Research Database (Denmark)

    Wang, Lei; Yao, Zhi-Jun; Jiang, Liguang;

    2016-01-01

    The spatiotemporal changes in 21 indices of extreme temperature and precipitation for the Mongolian Plateau from 1951 to 2012 were investigated on the basis of daily temperature and precipitation data from 70 meteorological stations. Changes in catastrophic events, such as droughts, floods, and s...

  1. Deterioration modeling for condition assessment of flexible pavements considering extreme weather events

    Science.gov (United States)

    Hashemi Tari, Yasamin; Shahini Shamsabadi, Salar; Birken, Ralf; Wang, Ming

    2015-04-01

    Accurate pavement management systems are essential for states' Department Of Transportation and roadway agencies to plan for cost-effective maintenance and repair (M and R) strategies. Pavement deterioration model is an imperative component of any pavement management system since the future budget and M and R plans would be developed based on the predicted pavement performance measures. It is crucial for the pavement deterioration models to consider the factors that significantly aggravate the pavement condition. While many studies have highlighted the impact of different environmental, load, and pavement's structure on the life cycle of the pavement, effect of extreme weather events such as Floods and Snow Storms have often been overlooked. In this study, a pavement deterioration model is proposed which would consider the effect of traffic loads, climate conditions, and extreme weather events. Climate, load and performance data has been compiled for over twenty years and for eight states using the Long Term Pavement Performance (LTPP) and National Oceanic and Atmospheric Administration (NOAA) databases. A stepwise regression approach is undertaken to quantify the effect of the extreme weather events, along with other influential factors on pavement performance in terms of International Roughness Index (IRI). Final results rendered more than 90% correlation with the quantified impact values of extreme weather events.

  2. The Challenges from Extreme Climate Events for Sustainable Development in Amazonia: the Acre State Experience

    Science.gov (United States)

    Araújo, M. D. N. M.

    2015-12-01

    In the past ten years Acre State, located in Brazil´s southwestern Amazonia, has confronted sequential and severe extreme events in the form of droughts and floods. In particular, the droughts and forest fires of 2005 and 2010, the 2012 flood within Acre, the 2014 flood of the Madeira River which isolated Acre for two months from southern Brazil, and the most severe flooding throughout the state in 2015 shook the resilience of Acrean society. The accumulated costs of these events since 2005 have exceeded 300 million dollars. For the last 17 years, successive state administrations have been implementing a socio-environmental model of development that strives to link sustainable economic production with environmental conservation, particularly for small communities. In this context, extreme climate events have interfered significantly with this model, increasing the risks of failure. The impacts caused by these events on development in the state have been exacerbated by: a) limitations in monitoring; b) extreme events outside of Acre territory (Madeira River Flood) affecting transportation systems; c) absence of reliable information for decision-making; and d) bureaucratic and judicial impediments. Our experience in these events have led to the following needs for scientific input to reduce the risk of disasters: 1) better monitoring and forecasting of deforestation, fires, and hydro-meteorological variables; 2) ways to increase risk perception in communities; 3) approaches to involve more effectively local and regional populations in the response to disasters; 4) more accurate measurements of the economic and social damages caused by these disasters. We must improve adaptation to and mitigation of current and future extreme climate events and implement a robust civil defense, adequate to these new challenges.

  3. Solar Energetic Particle Event Associated with the 2012 July 23 Extreme Solar Storm

    CERN Document Server

    Zhu, Bei; Luhmann, Janet G; Hu, Huidong; Wang, Rui; Yang, Zhongwei

    2016-01-01

    We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which STEREO and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a superfast shock and extremely enhanced ejecta magnetic fields observed near 1 AU at STEREO A, was caused by the combination of successive coronal mass ejections (CMEs). Meanwhile, energetic particles were observed by STEREO and near-Earth spacecraft such as ACE and SOHO, suggestive of a wide longitudinal spread of the particles at 1 AU. Combining the SEP observations with in situ plasma and magnetic field measurements we investigate the longitudinal distribution of the SEP event in connection with the associated shock and CMEs. Our results underscore the complex magnetic configuration of the inner heliosphere formed by solar eruptions. The examinations of particle intensities, proton anisotropy distributions, element abundance ratios, magnetic connectivity and spectra also g...

  4. Emergency Response to and Preparedness for Extreme Weather Events and Environmental Changes in China.

    Science.gov (United States)

    Wang, Li; Liao, Yongfeng; Yang, Linsheng; Li, Hairong; Ye, Bixiong; Wang, Wuyi

    2016-03-01

    China has achieved impressive rapid economic growth over the past 30 years but accompanied by significant extreme weather events and environmental changes caused by global change and overfast urbanization. Using the absolute hazards index (AHI), we assessed the spatial distribution patterns and related health effects of 4 major extreme natural disasters, including drought, floods (landslides, mudslides), hails, and typhoons from 2000 to 2011 at the provincial level in China. The results showed that (1) central and south China were the most affected by the 4 natural disasters, and north China suffered less; (2) the provinces with higher AHI suffered most from total death, missing people, collapse, and emergently relocated population; (3) the present health emergency response system to disasters in China mainly lacks a multidisciplinary approach. In the concluding section of this article, suggestions on preparedness and rapid response to extreme health events from environmental changes are proposed. PMID:25246501

  5. Assessment of climate variations in temperature and precipitation extreme events over Iran

    Science.gov (United States)

    Soltani, M.; Laux, P.; Kunstmann, H.; Stan, K.; Sohrabi, M. M.; Molanejad, M.; Sabziparvar, A. A.; Ranjbar SaadatAbadi, A.; Ranjbar, F.; Rousta, I.; Zawar-Reza, P.; Khoshakhlagh, F.; Soltanzadeh, I.; Babu, C. A.; Azizi, G. H.; Martin, M. V.

    2015-09-01

    In this study, changes in the spatial and temporal patterns of climate extreme indices were analyzed. Daily maximum and minimum air temperature, precipitation, and their association with climate change were used as the basis for tracking changes at 50 meteorological stations in Iran over the period 1975-2010. Sixteen indices of extreme temperature and 11 indices of extreme precipitation, which have been quality controlled and tested for homogeneity and missing data, are examined. Temperature extremes show a warming trend, with a large proportion of stations having statistically significant trends for all temperature indices. Over the last 15 years (1995-2010), the annual frequency of warm days and nights has increased by 12 and 14 days/decade, respectively. The number of cold days and nights has decreased by 4 and 3 days/decade, respectively. The annual mean maximum and minimum temperatures averaged across Iran both increased by 0.031 and 0.059 °C/decade. The probability of cold nights has gradually decreased from more than 20 % in 1975-1986 to less than 15 % in 1999-2010, whereas the mean frequency of warm days has increased abruptly between the first 12-year period (1975-1986) and the recent 12-year period (1999-2010) from 18 to 40 %, respectively. There are no systematic regional trends over the study period in total precipitation or in the frequency and duration of extreme precipitation events. Statistically significant trends in extreme precipitation events are observed at less than 15 % of all weather stations, with no spatially coherent pattern of change, whereas statistically significant changes in extreme temperature events have occurred at more than 85 % of all weather stations, forming strongly coherent spatial patterns.

  6. Vulnerability and resilience of European ecosystems towards extreme climatic events: The ecosystem perspective

    Science.gov (United States)

    Thonicke, Kirsten; Rolinski, Susanne; Walz, Ariane; von Bloh, Werner; van Oijen, Marcel; Davin, Edouard; Vieli, Barla; Kato, Tomomichi; Beer, Christian

    2014-05-01

    Extremes of meteorological events may but do not have to cause damages in ecosystems. Climate change is expected to have a strong impact on the resilience and stability of ecosystems worldwide. So far, the impacts of trends and extremes of physical drivers on ecosystems have generally been studied regardless of the extremeness of the ecosystem response. We base our analysis on a Probabilistic Risk Assessment concept of Van Oijen et al. (2013) quantifying the vulnerability of vegetation dynamics in relation to the extremeness of meteorological drivers such as temperature, precipitation or drought indices. Here, the definition of extreme, hazardous weather conditions is based on the ecosystem response. Instead of searching for extreme meteorological events, we define extreme ecosystem responses in terms of threshold levels of carbon uptake, and search for the meteorological conditions which are responsible. Having defined hazardous events in this way, we quantify the vulnerability or resilience of ecosystems to such hazards. We apply this approach on results of different vegetation models (such as LPJmL, Orchidee, JSBACH or CLM4) and the forest model BASFOR using climatic input for Europe from the WATCH-ERAI-REMO climate dataset with the SRES A1B emission scenario. Our results show that under current climatic conditions, the southern part of Europe already suffers severe heat and drought stress which is reflected in our approach by vulnerability values being high for precipitation, relatively high for the SPEI index, moderately high for temperature and quite high for the consecutive dry days. Thus, hazard occurrence is frequent enough to determine ecosystem vulnerability but this depends on the definition of the threshold of hazardous ecosystem responses. Vulnerability values in the Mediterranean increase towards the end of the 21st century for all models indicating that a tipping point towards drought damages has been reached for the chosen climate scenario.

  7. Analysis of the Impact of Climate Change on Extreme Hydrological Events in California

    Science.gov (United States)

    Ashraf Vaghefi, Saeid; Abbaspour, Karim C.

    2016-04-01

    Estimating magnitude and occurrence frequency of extreme hydrological events is required for taking preventive remedial actions against the impact of climate change on the management of water resources. Examples include: characterization of extreme rainfall events to predict urban runoff, determination of river flows, and the likely severity of drought events during the design life of a water project. In recent years California has experienced its most severe drought in recorded history, causing water stress, economic loss, and an increase in wildfires. In this paper we describe development of a Climate Change Toolkit (CCT) and demonstrate its use in the analysis of dry and wet periods in California for the years 2020-2050 and compare the results with the historic period 1975-2005. CCT provides four modules to: i) manage big databases such as those of Global Climate Models (GCMs), ii) make bias correction using observed local climate data , iii) interpolate gridded climate data to finer resolution, and iv) calculate continuous dry- and wet-day periods based on rainfall, temperature, and soil moisture for analysis of drought and flooding risks. We used bias-corrected meteorological data of five GCMs for extreme CO2 emission scenario rcp8.5 for California to analyze the trend of extreme hydrological events. The findings indicate that frequency of dry period will increase in center and southern parts of California. The assessment of the number of wet days and the frequency of wet periods suggests an increased risk of flooding in north and north-western part of California, especially in the coastal strip. Keywords: Climate Change Toolkit (CCT), Extreme Hydrological Events, California

  8. Sea extreme events during the last millennium in north-east of Morocco

    Directory of Open Access Journals (Sweden)

    O. Raji

    2014-03-01

    Full Text Available The Moroccan Mediterranean coast is located in one of the most vulnerable area to extreme weather events or tsunami hazards. The objective of this research is to reconstruct the historical extreme submersion-events record using sea-induced deposits preserved in coastal lagoon. The Nador lagoon is the largest Moroccan lagoon (115 km2 located along the Western Mediterranean which presents a high cyclogenetic character and is exposed to tsunamis from Alboran Sea. The sandy barrier which separates the lagoon from the Mediterranean Sea is marked by many overwashes, which indicate how intensely has been exposed to the adverse sea events through history. Using the UWITEC coring platform, an undisturbed MC4.5 core (1.15 m long was successfully sampled in the studied lagoon. To identify sea extreme events, a multi-proxy approach was applied combining sedimentogical and geochemical data. The preliminary results show that the identified paleo-events are concentrated over the last 500 years. The challenge that remains now is to distinguish between the tsunami and the storm deposits.

  9. Subsurface signatures and timing of extreme wave events along the southeast Indian coast

    Indian Academy of Sciences (India)

    Rajesh R Nair; Madhav K Murari; C S Vijaya Lakshmi; Ilya Buynevich; Ron J Goble; P Srinivasan; S G N Murthy; Deshraj Trivedi; Suresh Chandra Kandpal; S M Hussain; D Sengupta; Ashok K Singhvi

    2011-10-01

    Written history’s limitation becomes apparent when attempting to document the predecessors of extreme coastal events in the Indian Ocean, from 550–700 years in Thailand and 1000 years in Indonesia. Detailed ground-penetrating radar (GPR) surveys in Mahabalipuram, southeast India, complemented with sedimentological analyses, magnetic susceptibility measurements, and optical dating provide strong evidence of extreme wave events during the past 3700 years. The diagnostic event signatures include the extent and elevation of the deposits, as well as morphologic similarity of buried erosional scarps to those reported in northern Sumatra region. Optical ages immediately overlying the imaged discontinuities that coincides with high concentration of heavy minerals date the erosional events to 340 ± 35, 350 ± 20, 490 ± 30, 880 ± 40, 1080 ± 60, 1175 ± 188, 2193 ± 266, 2235 ± 881, 2489 ± 293, 2450 ± 130, 2585 ± 609, 3710 ± 200 years ago. These evidences are crucial in reconstructing paleo extreme wave events and will pave the way for regional correlation of erosional horizons along the northern margin of Indian Ocean.

  10. Total ozone and Umkehr observations at Hoher Sonnblick 1994-2011: Climatology and extreme events

    Science.gov (United States)

    Fitzka, M.; Hadzimustafic, J.; Simic, S.

    2014-01-01

    Umkehr and total ozone measurements have been carried out at Hoher Sonnblick (47.05°N, 12.95°E; 3106 m above sea level) since 1994 with the Brewer MkIV #093 spectrophotometer. These measurements are used to investigate trends in total and vertically resolved ozone in the period 1994-2011 and for establishing an Umkehr climatology. A method to estimate daily thresholds for extreme events in total ozone (TO3) based on skewed log-Weibull distributions is presented and applied to the record. An analysis of the such defined extreme events reveals a significant decline in the number of low events, whereas the high events increased by about the same amount. However, no significant trend is observed in the magnitude of extreme events. Solar activity and equivalent effective stratospheric chlorine show weak to no correlation with vertically resolved ozone, presumably due to the record's limited extent, while tropopause pressure and quasi-biennial oscillation show a significant influence. Trend analysis of total and vertically resolved ozone indicates a significant increase in TO3 of 2.0% per decade since 1994, whereas no recovery is observed in the upper stratosphere. While ozone concentrations continue to decrease or stagnate in the upper stratosphere, the loss is overcompensated by large gains in the lowest layers during winter, leading to a significant overall increase in TO3. During events with extremely low TO3, the largest deficiencies are found in the bottommost layers with a marked seasonal component. The topmost layers mainly contribute to TO3 reductions during late winter and fall.

  11. Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

    International Nuclear Information System (INIS)

    One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January–February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (∼5–20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties. (letter)

  12. AP1000R design robustness against extreme external events - Seismic, flooding, and aircraft crash

    International Nuclear Information System (INIS)

    Both the International Atomic Energy Agency (IAEA) and the U.S. Nuclear Regulatory Commission (NRC) require existing and new nuclear power plants to conduct plant assessments to demonstrate the unit's ability to withstand external hazards. The events that occurred at the Fukushima-Dai-ichi nuclear power station demonstrated the importance of designing a nuclear power plant with the ability to protect the plant against extreme external hazards. The innovative design of the AP1000R nuclear power plant provides unparalleled protection against catastrophic external events which can lead to extensive infrastructure damage and place the plant in an extended abnormal situation. The AP1000 plant is an 1100-MWe pressurized water reactor with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. The plant's compact safety related footprint and protection provided by its robust nuclear island structures prevent significant damage to systems, structures, and components required to safely shutdown the plant and maintain core and spent fuel pool cooling and containment integrity following extreme external events. The AP1000 nuclear power plant has been extensively analyzed and reviewed to demonstrate that it's nuclear island design and plant layout provide protection against both design basis and extreme beyond design basis external hazards such as extreme seismic events, external flooding that exceeds the maximum probable flood limit, and malicious aircraft impact. The AP1000 nuclear power plant uses fail safe passive features to mitigate design basis accidents. The passive safety systems are designed to function without safety-grade support systems (such as AC power, component cooling water, service water, compressed air or HVAC). The plant has been designed to protect systems, structures, and components critical to placing the reactor in a safe shutdown condition within the steel containment vessel which is

  13. Urban-Induced Mechanisms for an Extreme Rainfall Event in Beijing China: A Satellite Perspective

    Directory of Open Access Journals (Sweden)

    Menglin S. Jin

    2015-03-01

    Full Text Available Using 1 km satellite remote sensing observations, this paper examines the clouds, aerosols, water vapor and surface skin temperature over Beijing to understand the possible urban system contributions to the extreme rainfall event on 21 July 2012 (i.e., 721 event. Remote sensing measurements, with the advantage of high spatial resolution and coverage, reveal three key urban-related mechanisms: (a the urban heat island effect (UHI resulted in strong surface convection and high level cloud cover over Beijing; (b urban aerosol amount peaked before the rainfall, which “seeded” the clouds and invigorated precipitation; and (c urban tall buildings provided additional lift for the air mass and provided heat at the underlying boundary to keep the rainfall system alive for a long duration precipitation (>10 hours. With the existing rainfall system moving from the northwest and abundant water vapor was transported from the southeast into Beijing, the urban canyon-lifting, aerosol, and UHI effects all enhanced this extreme rainfall event. This work proves that urban system is responsible, at least partly, for urban rainfall extremes and thus should be considered for urban extreme rainfall prediction in the future.

  14. Current status and issues of external event PSA for extreme natural hazards after Fukushima accident

    International Nuclear Information System (INIS)

    Extreme external events is emerged as significant risk contributor to the nuclear power plants after Fukushima Daiichi accident due to the catastrophic earthquake followed by great tsunami greater than a design basis. This accident shows that the extreme external events have the potential to simultaneously affect redundant and diverse safety systems and thereby induce common cause failure or common cause initiators. The probabilistic risk assessment methodology has been used for the risk assessment and safety improvement against the extreme natural hazards. The earthquake and tsunami hazard is an important issue for the nuclear industry in Korea. In this paper, the role and application of probabilistic safety assessment for the post Fukushima action will be introduced. For the evaluation of the extreme natural hazard, probabilistic seismic and tsunami hazard analysis is being performed for the safety enhancement. The research activity on the external event PSA and its interim results will be introduced with the issues to be solved in the future for the reliability enhancement of the risk analysis results. (authors)

  15. Antarctic climate change: extreme events disrupt plastic phenotypic response in Adelie penguins.

    Directory of Open Access Journals (Sweden)

    Amélie Lescroël

    Full Text Available In the context of predicted alteration of sea ice cover and increased frequency of extreme events, it is especially timely to investigate plasticity within Antarctic species responding to a key environmental aspect of their ecology: sea ice variability. Using 13 years of longitudinal data, we investigated the effect of sea ice concentration (SIC on the foraging efficiency of Adélie penguins (Pygoscelis adeliae breeding in the Ross Sea. A 'natural experiment' brought by the exceptional presence of giant icebergs during 5 consecutive years provided unprecedented habitat variation for testing the effects of extreme events on the relationship between SIC and foraging efficiency in this sea-ice dependent species. Significant levels of phenotypic plasticity were evident in response to changes in SIC in normal environmental conditions. Maximum foraging efficiency occurred at relatively low SIC, peaking at 6.1% and decreasing with higher SIC. The 'natural experiment' uncoupled efficiency levels from SIC variations. Our study suggests that lower summer SIC than currently observed would benefit the foraging performance of Adélie penguins in their southernmost breeding area. Importantly, it also provides evidence that extreme climatic events can disrupt response plasticity in a wild seabird population. This questions the predictive power of relationships built on past observations, when not only the average climatic conditions are changing but the frequency of extreme climatic anomalies is also on the rise.

  16. The Definition and Classification of Extensive and Persistent Extreme Cold Events in China

    Institute of Scientific and Technical Information of China (English)

    PENG Jing-Bei; BUEH Cholaw

    2011-01-01

    Using the observed daily temperatures from 756 stations in China during the period from 1951 to 2009, extensive and persistent extreme cold events (EPECEs) were defined according to the following three steps: 1) a station was defined as an extreme cold station (ECS) if the observed temperature was lower than its 10th percentile threshold; 2) an extensive extreme cold event was determined to be present if the approximated area occupied by the ECSs was more than 10% of the total area of China (83rd percentile) on its starting day and the maximum area occupied by the ECSs was at least 20% of the total area of China (96th percentile); and 3) an EPECE was determined to be present if the extensive extreme cold event lasted for at least for eight days. 52 EPECEs were identified in this manner, and these identification results were also verified using other reliable data. On the basis of cluster analysis, five types of EPECEs were classified according to the spatial distribution of ECSs at their most extensive time over the course of the EPECE.

  17. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events.

    Science.gov (United States)

    Choudhary, Sonal; Blaud, Aimeric; Osborn, A Mark; Press, Malcolm C; Phoenix, Gareth K

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem (15)N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2gNm(-2)yr(-1), applied as (15)NH4(15)NO3 in Svalbard (79(°)N), during the summer. Separate applications of (15)NO3(-) and (15)NH4(+) were also made to determine the importance of N form in their retention. More than 95% of the total (15)N applied was recovered after one growing season (~90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants>vascular plants>organic soil>litter>mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of (15)N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater (15)NO3(-) than (15)NH4(+), suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events may represent a major source of eutrophication. PMID:26956177

  18. The impacts of '05.6' extreme flood event on riverine carbon fluxes in Xijiang River

    Institute of Scientific and Technical Information of China (English)

    SUN HuiGuo; HAN JingTai; ZHANG ShuRong; LU XiXi

    2007-01-01

    An extreme flood event with a frequency of nearly 200 year occurred in June of 2005 in the Xijiang River,the main trunk stream of the Zhujiang River. Samples were systematically collected during the flood event, and water quality parameters, including total suspended sediment (TSS), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and particulate organic carbon (POC) were analyzed,and riverine carbon concentrations associated with its changing pattern through the flood process were discussed. These parameters reflect the changes in basin surface flow and subsurface flow during the flood. This flood event influenced annual flux estimations of POC, DOC, and DIC to great extents.Based on carbon flux estimations for the year 2005 and the flood event (June 21-28) in the Xijiang River, it was found that DIC, DOC, and POC fluxes during '05.6' flood event are 1.52x106 g.km-2.a-1,0.24x106 g.km-2.a-1, and 0.54x106 g.km-2.a-1, and account for 14.87%, 24.75% and 44.89% of the annual fluxes in 2005, respectively. The results suggested that carbon exports during extreme flood events had great contributions to the total carbon fluxes and composition of various carbon components, being important for accurate estimates of annual carbon fluxes in rivers with frequent floods.

  19. Simulation of the 23 July 2012 Extreme Space Weather Event: What if This Extremely Rare CME Was Earth Directed?

    Science.gov (United States)

    Ngwira, Chigomezyo M.; Pulkkinen, Antti; Mays, M. Leila; Kuznetsova, Maria M.; Galvin, A. B.; Simunac, Kristin; Baker, Daniel N.; Li, Xinlin; Zheng, Yihua; Glocer, Alex

    2013-01-01

    Extreme space weather events are known to cause adverse impacts on critical modern day technological infrastructure such as high-voltage electric power transmission grids. On 23 July 2012, NASA's Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft observed in situ an extremely fast coronal mass ejection (CME) that traveled 0.96 astronomical units (approx. 1 AU) in about 19 h. Here we use the SpaceWeather Modeling Framework (SWMF) to perform a simulation of this rare CME.We consider STEREO-A in situ observations to represent the upstream L1 solar wind boundary conditions. The goal of this study is to examine what would have happened if this Rare-type CME was Earth-bound. Global SWMF-generated ground geomagnetic field perturbations are used to compute the simulated induced geoelectric field at specific ground-based active INTERMAGNET magnetometer sites. Simulation results show that while modeled global SYM-H index, a high-resolution equivalent of the Dst index, was comparable to previously observed severe geomagnetic storms such as the Halloween 2003 storm, the 23 July CME would have produced some of the largest geomagnetically induced electric fields, making it very geoeffective. These results have important practical applications for risk management of electrical power grids.

  20. Quantifying population exposure to airborne particulate matter during extreme events in California due to climate change

    Directory of Open Access Journals (Sweden)

    A. Mahmud

    2012-02-01

    Full Text Available The effect of climate change on population-weighted concentrations of particulate matter (PM during extreme events was studied using the Parallel Climate Model (PCM, the Weather Research and Forecasting (WRF model and the UCD/CIT 3-D photochemical air quality model. A "business as usual" (B06.44 global emissions scenario was dynamically downscaled for the entire state of California between the years 2000–2006 and 2047–2053. Air quality simulations were carried out for 1008 days in each of the present-day and future climate conditions using year-2000 emissions. Population-weighted concentrations of PM0.1, PM2.5, and PM10 total mass, components species, and primary source contributions were calculated for California and three air basins: the Sacramento Valley air basin (SV, the San Joaquin Valley air basin (SJV and the South Coast Air Basin (SoCAB. Results over annual-average periods were contrasted with extreme events.

    Climate change between 2000 vs. 2050 did not cause a statistically significant change in annual-average population-weighted PM2.5 mass concentrations within any major sub-region of California in the current study. Climate change did alter the annual-average composition of the airborne particles in the SoCAB, with notable reductions of elemental carbon (EC; −3% and organic carbon (OC; −3% due to increased annual-average wind speeds that diluted primary concentrations from gasoline combustion (−3% and food cooking (−4%. In contrast, climate change caused significant increases in population-weighted PM2.5 mass concentrations in central California during extreme events. The maximum 24-h average PM2.5 concentration experienced by an average person during a ten-year period in the SJV increased by 21% due to enhanced production of secondary particulate matter (manifested as NH4NO3. In general, climate change caused increased

  1. A few extreme events dominate global interannual variability in gross primary production

    International Nuclear Information System (INIS)

    Understanding the impacts of climate extremes on the carbon cycle is important for quantifying the carbon-cycle climate feedback and highly relevant to climate change assessments. Climate extremes and fires can have severe regional effects, but a spatially explicit global impact assessment is still lacking. Here, we directly quantify spatiotemporal contiguous extreme anomalies in four global data sets of gross primary production (GPP) over the last 30 years. We find that positive and negative GPP extremes occurring on 7% of the spatiotemporal domain explain 78% of the global interannual variation in GPP and a significant fraction of variation in the net carbon flux. The largest thousand negative GPP extremes during 1982–2011 (4.3% of the data) account for a decrease in photosynthetic carbon uptake of about 3.5 Pg C yr−1, with most events being attributable to water scarcity. The results imply that it is essential to understand the nature and causes of extremes to understand current and future GPP variability. (paper)

  2. Variability of extreme climate events in the territory and water area of Russia

    Science.gov (United States)

    Serykh, Ilya; Kostianoy, Andrey

    2016-04-01

    The Fourth (2007) and Fifth (2014) Assessment Reports on Climate Change of the Intergovernmental Panel on Climate Change (IPCC) state that in the XXI century, climate change will be accompanied by an increase in the frequency, intensity and duration of extreme nature events such as: extreme precipitation and extreme high and low air temperatures. All these will lead to floods, droughts, fires, shallowing of rivers, lakes and water reservoirs, desertification, dust storms, melting of glaciers and permafrost, algal bloom events in the seas, lakes and water reservoirs. In its turn, these events will lead to chemical and biological contamination of water, land and air. These events will result in a deterioration of quality of life, significant financial loss due to damage to the houses, businesses, roads, agriculture, forestry, tourism, and in many cases they end in loss of life. These predictions are confirmed by the results of the studies presented in the RosHydromet First (2008) and Second (2014) Assessment Reports on Climate Change and its Consequences in Russian Federation. Scientists predictions have been repeatedly confirmed in the last 15 years - floods in Novorossiysk (2002), Krymsk and Gelendzhik (2012), the Far East (2013), heat waves in 2010, unusually cold winter (February) of 2012 and unusually warm winter of 2013/2014 in the European territory of Russia. In this regard, analysis and forecasting of extreme climate events associated with climate change in the territory of Russia are an extremely important task. This task is complicated by the fact that modern atmospheric models used by IPCC and RosHydromet badly reproduce and predict the intensity of precipitation. We are analyzing meteorological reanalysis data (NCEP/NCAR, 20th Century Reanalysis, ERA-20C, JRA-55) and satellite data (NASA and AVISO) on air, water and land temperature, rainfall, wind speed and cloud cover, water levels in seas and lakes, index of vegetation over the past 30-60 years

  3. Using Dynamically Downscaled Climate Model Outputs to Inform Projections of Extreme Precipitation Events

    Science.gov (United States)

    Wobus, Cameron; Reynolds, Lara; Jones, Russell; Horton, Radley; Smith, Joel; Fries, J. Stephen; Tryby, Michael; Spero, Tanya; Nolte, Chris

    2015-01-01

    Many of the storms that generate damaging floods are caused by locally intense, sub-daily precipitation, yet the spatial and temporal resolution of the most widely available climate model outputs are both too coarse to simulate these events. Thus there is often a disconnect between the nature of the events that cause damaging floods and the models used to project how climate change might influence their magnitude. This could be a particular problem when developing scenarios to inform future storm water management options under future climate scenarios. In this study we sought to close this gap, using sub-daily outputs from the Weather Research and Forecasting model (WRF) from each of the nine climate regions in the United States. Specifically, we asked 1) whether WRF outputs projected consistent patterns of change for sub-daily and daily precipitation extremes; and 2) whether this dynamically downscaled model projected different magnitudes of change for 3-hourly vs 24-hourly extreme events. We extracted annual maximum values for 3-hour through 24-hour precipitation totals from an 11-year time series of hindcast (1995-2005) and mid-century (2045-2055) climate, and calculated the direction and magnitude of change for 3-hour and 24-hour extreme events over this timeframe. The model results project that the magnitude of both 3-hour and 24-hour events will increase over most regions of the United States, but there was no clear or consistent difference in the relative magnitudes of change for sub-daily vs daily events.

  4. Credible occurrence probabilities for extreme geophysical events: earthquakes, volcanic eruptions, magnetic storms

    Science.gov (United States)

    Love, Jeffrey J.

    2012-01-01

    Statistical analysis is made of rare, extreme geophysical events recorded in historical data -- counting the number of events $k$ with sizes that exceed chosen thresholds during specific durations of time $\\tau$. Under transformations that stabilize data and model-parameter variances, the most likely Poisson-event occurrence rate, $k/\\tau$, applies for frequentist inference and, also, for Bayesian inference with a Jeffreys prior that ensures posterior invariance under changes of variables. Frequentist confidence intervals and Bayesian (Jeffreys) credibility intervals are approximately the same and easy to calculate: $(1/\\tau)[(\\sqrt{k} - z/2)^{2},(\\sqrt{k} + z/2)^{2}]$, where $z$ is a parameter that specifies the width, $z=1$ ($z=2$) corresponding to $1\\sigma$, $68.3\\%$ ($2\\sigma$, $95.4\\%$). If only a few events have been observed, as is usually the case for extreme events, then these "error-bar" intervals might be considered to be relatively wide. From historical records, we estimate most likely long-term occurrence rates, 10-yr occurrence probabilities, and intervals of frequentist confidence and Bayesian credibility for large earthquakes, explosive volcanic eruptions, and magnetic storms.

  5. Climate Central World Weather Attribution (WWA) project: Real-time extreme weather event attribution analysis

    Science.gov (United States)

    Haustein, Karsten; Otto, Friederike; Uhe, Peter; Allen, Myles; Cullen, Heidi

    2015-04-01

    Extreme weather detection and attribution analysis has emerged as a core theme in climate science over the last decade or so. By using a combination of observational data and climate models it is possible to identify the role of climate change in certain types of extreme weather events such as sea level rise and its contribution to storm surges, extreme heat events and droughts or heavy rainfall and flood events. These analyses are usually carried out after an extreme event has occurred when reanalysis and observational data become available. The Climate Central WWA project will exploit the increasing forecast skill of seasonal forecast prediction systems such as the UK MetOffice GloSea5 (Global seasonal forecasting system) ensemble forecasting method. This way, the current weather can be fed into climate models to simulate large ensembles of possible weather scenarios before an event has fully emerged yet. This effort runs along parallel and intersecting tracks of science and communications that involve research, message development and testing, staged socialization of attribution science with key audiences, and dissemination. The method we employ uses a very large ensemble of simulations of regional climate models to run two different analyses: one to represent the current climate as it was observed, and one to represent the same events in the world that might have been without human-induced climate change. For the weather "as observed" experiment, the atmospheric model uses observed sea surface temperature (SST) data from GloSea5 (currently) and present-day atmospheric gas concentrations to simulate weather events that are possible given the observed climate conditions. The weather in the "world that might have been" experiments is obtained by removing the anthropogenic forcing from the observed SSTs, thereby simulating a counterfactual world without human activity. The anthropogenic forcing is obtained by comparing the CMIP5 historical and natural simulations

  6. A comparison of ensemble post-processing methods for extreme events

    Science.gov (United States)

    Williams, Robin; Ferro, Chris; Kwasniok, Frank

    2015-04-01

    Ensemble post-processing methods are used in operational weather forecasting to form probability distributions that represent forecast uncertainty. Several such methods have been proposed in the literature, including logistic regression, ensemble dressing, Bayesian model averaging and non-homogeneous Gaussian regression. We conduct an imperfect model experiment with the Lorenz 1996 model to investigate the performance of these methods, especially when forecasting the occurrence of rare extreme events. We show how flexible bias-correction schemes can be incorporated into these post-processing methods, and that allowing the bias correction to depend on the ensemble mean can yield considerable improvements in skill when forecasting extreme events. In the Lorenz 1996 setting, we find that ensemble dressing, Bayesian model averaging and non-homogeneous Gaussian regression perform similarly, while logistic regression performs less well.

  7. Comparison of annual maximum series and partial duration series methods for modeling extreme hydrologic events

    DEFF Research Database (Denmark)

    Madsen, Henrik; Rasmussen, Peter F.; Rosbjerg, Dan

    1997-01-01

    Two different models for analyzing extreme hydrologic events, based on, respectively, partial duration series (PDS) and annual maximum series (AMS), are compared. The PDS model assumes a generalized Pareto distribution for modeling threshold exceedances corresponding to a generalized extreme value......, and the PDS model with ML estimation for large positive shape parameters. Since heavy-tailed distributions, corresponding to negative shape parameters, are far the most common in hydrology, the PDS model generally is to be preferred for at-site quantile estimation....... distribution for annual maxima. The performance of the two models in terms of the uncertainty of the T-year event estimator is evaluated in the cases of estimation with, respectively, the maximum likelihood (ML) method, the method of moments (MOM), and the method of probability weighted moments (PWM). In the...

  8. Resilience of coastal wetlands to extreme hydrologic events in Apalachicola Bay

    Science.gov (United States)

    Tahsin, Subrina; Medeiros, Stephen C.; Singh, Arvind

    2016-07-01

    Extreme hydrologic events such as hurricanes and droughts continuously threaten wetlands which provide key ecosystem services in coastal areas. The recovery time for vegetation after impact from these extreme events can be highly variable depending on the hazard type and intensity. Apalachicola Bay in Florida is home to a rich variety of saltwater and freshwater wetlands and is subject to a wide range of hydrologic hazards. Using spatiotemporal changes in Landsat-based empirical vegetation indices, we investigate the impact of hurricane and drought on both freshwater and saltwater wetlands from year 2000 to 2015 in Apalachicola Bay. Our results indicate that saltwater wetlands are more resilient than freshwater wetlands and suggest that in response to hurricanes, the coastal wetlands took almost a year to recover, while recovery following a drought period was observed after only a month.

  9. Future extreme events in European climate: an exploration of regional climate model projections

    OpenAIRE

    Beniston, Martin; Stephenson, David B.; Christensen, Ole B.; Ferro, Christopher A. T.; Frei, Christoph; Goyette, Stéphane; Halsnaes, Kirsten; Holt, Tom; Jylhä, Kirsti; Koffi, Brigitte; Palutikof, Jean; Schöll, Regina; Semmler, Tido; Woth, Katja

    2007-01-01

    This paper presents an overview of changes in the extreme events that are most likely to affect Europe in forthcoming decades. A variety of diagnostic methods are used to determine how heat waves, heavy precipitation, drought, wind storms, and storm surges change between present (1961–90) and future (2071–2100) climate on the basis of regional climate model simulations produced by the PRUDENCE project. A summary of the main results follows. Heat waves – Regional surface warming causes the fre...

  10. Extreme climatic events: impacts of drought and high temperature on physiological processes in agronomically important plants

    OpenAIRE

    Feller, Urs; Vaseva, Irina I

    2014-01-01

    Climate models predict more frequent and more severe extreme events (e.g., heat waves, extended drought periods, flooding) in many regions for the next decades. The impact of adverse environmental conditions on crop plants is ecologically and economically relevant. This review is focused on drought and heat effects on physiological status and productivity of agronomically important plants. Stomatal opening represents an important regulatory mechanism during drought and heat stress since it in...

  11. TARGET CHOICE DURING EXTREME EVENTS: A DISCRETE SPATIAL CHOICE MODEL OF THE 2011 LONDON RIOTS

    OpenAIRE

    Baudains, P.; Braithwaite, A; Johnson, S. D.

    2013-01-01

    Riots are extreme events, and much of the early research on rioting suggested that the decision making of rioters was far from rational and could only be understood from the perspective of a collective mind. In the current study, we derive and test a set of expectations regarding rioter spatial decision making developed from theories originally intended to explain patterns of urban crime when law and order prevail—crime pattern and social disorganization theory—and consider theories of collec...

  12. Effects of climate change, extreme events and management on plants, pollinators and mutualistic interaction networks

    OpenAIRE

    Hoiß, Bernhard

    2013-01-01

    I. Climate change comprises average temperatures rise, changes in the distribution of precipitation and an increased amount and intensity of extreme climatic events in the last decades. Considering these serious changes in the abiotic environment it seems obvious that ecosystems also change. Flora and fauna have to adapt to the fast changing conditions, migrate or go extinct. This might result in shifts in biodiversity, species composition, species interactions and in ecosystem functioning an...

  13. Preface "Extreme events induced by weather and climate change: evaluation, forecasting and proactive planning"

    OpenAIRE

    A. Loukas; Llasat, M.-C.; U. Ulbrich

    2010-01-01

    This special issue of Natural Hazards and Earth System Sciences (NHESS) contains eight papers presented as oral or poster contributions in the Natural Hazards NH-1.2 session on"Extreme events induced by weather and climate change: evaluation, forecasting and proactive planning", held at the European Geosciences Union (EGU) General Assembly in Vienna, Austria, on 13-18 April 2008. The aim of the session was to provide an international forum for presenting new results and for discussing innovat...

  14. Regional growth curves and improved design value estimates of extreme precipitation events in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Kyselý, Jan; Picek, J.

    2007-01-01

    Roč. 33, č. 3 (2007), s. 243-255. ISSN 0936-577X R&D Projects: GA AV ČR KJB300420601 Institutional research plan: CEZ:AV0Z30420517 Keywords : extreme precipitation event * regional frequency analysis * design values * central Europe * Czech Republic Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.307, year: 2007 http://www.int-res.com/articles/cr2007/33/c033p243.pdf

  15. Species interactions determine the spatial mortality patterns emerging in plant communities after extreme events

    OpenAIRE

    Liao, Jinbao; Bogaert, Jan; Nijs, Ivan

    2015-01-01

    Abstract: Gap disturbance is assumed to maintain species diversity by creating environmental heterogeneity. However, little is known about how interactions with neighbours, such as competition and facilitation, alter the emerging gap patterns after extreme events. Using a spatially explicit community model we demonstrate that negative interactions, especially intraspecific competition, greatly promote both average gap size and gap-size diversity relative to positive interspecific interaction....

  16. Modelling the extreme precipitation event over Madeira Island on 20 February 2010

    Directory of Open Access Journals (Sweden)

    T. Luna

    2011-09-01

    Full Text Available In the morning of the 20 February of 2010 an extreme precipitation event occurred over Madeira Island. This event triggered several flash floods and mudslides in the southern parts of the island, resulting in 42 confirmed deaths, 100 injured, and at least 8 people still missing. These extreme weather conditions were associated to a weather frontal system moving northeastwards embedded in a low pressure area centered in the Azores archipelago. This storm was one in a series of such storms that affected Portugal, Spain, Morocco and the Canary islands causing flooding and strong winds. These storms were bolstered by an unusually strong sea surface temperature gradient across the Atlantic Ocean.

    In this study, the WRF model is used to evaluate the intensity and predictability of this precipitation extreme event over the island. The synoptic/orographic nature of the precipitation is also evaluated, as well as the sensitivity of the model to horizontal resolution and cumulus parameterization. Orography was found to be the main factor explaining the occurrence, amplitude and phase of precipitation over the Island.

  17. Herding interactions as an opportunity to prevent extreme events in financial markets

    Science.gov (United States)

    Kononovicius, Aleksejus; Gontis, Vygintas

    2015-07-01

    A characteristic feature of complex systems in general is a tight coupling between their constituent parts. In complex socio-economic systems this kind of behavior leads to self-organization, which may be both desirable (e.g. social cooperation) and undesirable (e.g. mass panic, financial "bubbles" or "crashes"). Abundance of the empirical data as well as general insights into the trading behavior enables the creation of simple agent-based models reproducing sophisticated statistical features of the financial markets. In this contribution we consider a possibility to prevent self-organized extreme events in financial market modeling its behavior using agent-based herding model, which reproduces main stylized facts of the financial markets. We show that introduction of agents with predefined fundamentalist trading behavior helps to significantly reduce the probability of the extreme price fluctuations events. We also investigate random trading, which was previously found to be promising extreme event prevention strategy, and find that its impact on the market has to be considered among other opportunities to stabilize the markets.

  18. Estimation of the impact of climate change-induced extreme precipitation events on floods

    Science.gov (United States)

    Hlavčová, Kamila; Lapin, Milan; Valent, Peter; Szolgay, Ján; Kohnová, Silvia; Rončák, Peter

    2015-09-01

    In order to estimate possible changes in the flood regime in the mountainous regions of Slovakia, a simple physically-based concept for climate change-induced changes in extreme 5-day precipitation totals is proposed in the paper. It utilizes regionally downscaled scenarios of the long-term monthly means of the air temperature, specific air humidity and precipitation projected for Central Slovakia by two regional (RCM) and two global circulation models (GCM). A simplified physically-based model for the calculation of short-term precipitation totals over the course of changing air temperatures, which is used to drive a conceptual rainfall-runoff model, was proposed. In the paper a case study of this approach in the upper Hron river basin in Central Slovakia is presented. From the 1981-2010 period, 20 events of the basin's most extreme average of 5-day precipitation totals were selected. Only events with continual precipitation during 5 days were considered. These 5-day precipitation totals were modified according to the RCM and GCM-based scenarios for the future time horizons of 2025, 2050 and 2075. For modelling runoff under changed 5-day precipitation totals, a conceptual rainfall-runoff model developed at the Slovak University of Technology was used. Changes in extreme mean daily discharges due to climate change were compared with the original flood events and discussed.

  19. Coping Strategies to Deal with Environmental Variability and Extreme Climatic Events in the Peruvian Anchovy Fishery

    Directory of Open Access Journals (Sweden)

    Marilú Bouchon

    2011-06-01

    Full Text Available The Peruvian anchovy fishery is the largest worldwide in terms of catches. The fishery started during the mid 1950s, and since then it has been highly dependent on natural stock fluctuations, due to the sensitivity of anchovy stocks to ocean-climate variability. The main driver of anchovy stock variability is the El Niño Southern Oscillation (ENSO, and three extreme ENSO warm events were recorded in 1972–1973, 1983–1984 and 1997–1998. This study investigates the evolution of coping strategies developed by the anchovy fisheries to deal with climate variability and extreme ENSO events. Results showed eight coping strategies to reduce impacts on the fishery. These included: decentralized installation of anchovy processing factories; simultaneous ownership of fishing fleet and processing factories; use of low-cost unloading facilities; opportunistic utilization of invading fish populations; low cost intensive monitoring; rapid flexible management; reduction of fishmeal price uncertainty through controlled production based on market demand; and decoupling of fishmeal prices from those of other protein-rich feed substitutes like soybean. This research shows that there are concrete lessons to be learned from successful adaptations to cope with climate change-related extreme climatic events that impact the supply of natural resources. The lessons can contribute to improved policies for coping with climate change in the commercial fishery sector.

  20. Plant Responses to Extreme Climatic Events: A Field Test of Resilience Capacity at the Southern Range Edge

    OpenAIRE

    Asier Herrero; Regino Zamora

    2014-01-01

    The expected and already observed increment in frequency of extreme climatic events may result in severe vegetation shifts. However, stabilizing mechanisms promoting community resilience can buffer the lasting impact of extreme events. The present work analyzes the resilience of a Mediterranean mountain ecosystem after an extreme drought in 2005, examining shoot-growth and needle-length resistance and resilience of dominant tree and shrub species (Pinus sylvestris vs Juniperus communis, and P...

  1. Temporal & Spatial Distribution of Extreme Heat Event in NYC Metro-Area

    Science.gov (United States)

    Alvi, M. N.

    2012-12-01

    Recent studies indicate an increase in extreme summer weather events that may be linked to global warming. Heat wave intensity and frequency trends are a relatively unexplored topic that may demonstrate a more pronounced global warming manifestation than general climate change. Extreme heat events have adverse effects on both, ecosystems and human health, killing over 70,000 in 2003 alone. This study aims to validate that extreme heat events have been increasing in intensity, frequency, duration and affected-area over the past 40 years. The importance of properly defining heat events is stressed. As there is no exact definition, this study uses the adjusted NOAA National Weather Service definition, in terms of heat index, a reference to human comfort as defined by temperature and humidity. A heat wave is defined when maximum outside conditions of human comfort levels are present for consecutive days. Complex cities such as New York (NYC) are also expected to experience more intense heat events when considering the Urban Heat Island Effect. To observe the extent of recent heat events in NYC, heat event trends were produced using data from up to 59 NYCMetNet surface weather stations covering all five boroughs of the City. Map comparisons of heat events from recent years (2010-2012) demonstrate an increase in the effected metro areas with concentrated maximums in the northwest part of the city, attributed to the dense urban landscape and a converging wind zone. To investigate temporal trends of heat waves in NYC, four NOAA-NCDC weather stations in the NYC Metro Area were used, providing data from 1973-2012. The time series results indicate that heat wave maximum intensities are increasing in NYC as a function of time since 1973 at a rate of 1.2°C/decade. The temporal plots demonstrate an annual increase in maximum intensity, frequency, and average event duration that could be attributed to increasing heat island and global warming. Future studies will expand this

  2. Processes and Geomorphological Impacts of an Extreme Flash Flood Event in SE Spain

    Science.gov (United States)

    Hooke, J.

    2015-12-01

    A major flash flood event took place on 28 September, 2012 in SE Spain, resulting in 10 fatalities and much damage to infrastructure regionally. The flood affected long-term monitoring sites in two catchments in which morphological changes and flow dynamics of these ephemeral channels were being measured. Thus detailed data on channel state prior to the flood were available. The flood event in the Nogalte catchment was extreme in its peak flow, rate of rise and unit runoff. The catchment has steep relief and much bare soil under almond groves, resulting in high sediment supply. The channel is confined in places, but mostly wide and braided, composed of loose gravel and occupying much of the valley floor. Flow was spatially continuous, with high connectivity throughout the catchment. The flood effects were net depositional in the monitored sites, with massive sedimentation on the channel bars. Vegetation was destroyed. Bank erosion and destruction of embankments took place in some locations. Hydraulic calculations indicate very high velocities, stream power and Froude numbers. Modelling and field evidence demonstrate extremely high sediment competence and sediment loadings. The influence of the event dynamics on processes and net outcomes is discussed. The impacts are compared with other events in this and neighbouring catchments. Overall, the event in the Nogalte did not alter the morphology markedly in spite of its extreme characteristics. It is suggested that these valley floors are adapted to this type of flash flood but that flows of such force and magnitude need to be allowed for in management in such an environment.

  3. An extreme climatic event alters marine ecosystem structure in a global biodiversity hotspot

    Science.gov (United States)

    Wernberg, Thomas; Smale, Dan A.; Tuya, Fernando; Thomsen, Mads S.; Langlois, Timothy J.; de Bettignies, Thibaut; Bennett, Scott; Rousseaux, Cecile S.

    2013-01-01

    Extreme climatic events, such as heat waves, are predicted to increase in frequency and magnitude as a consequence of global warming but their ecological effects are poorly understood, particularly in marine ecosystems. In early 2011, the marine ecosystems along the west coast of Australia--a global hotspot of biodiversity and endemism--experienced the highest-magnitude warming event on record. Sea temperatures soared to unprecedented levels and warming anomalies of 2-4°C persisted for more than ten weeks along >2,000km of coastline. We show that biodiversity patterns of temperate seaweeds, sessile invertebrates and demersal fish were significantly different after the warming event, which led to a reduction in the abundance of habitat-forming seaweeds and a subsequent shift in community structure towards a depauperate state and a tropicalization of fish communities. We conclude that extreme climatic events are key drivers of biodiversity patterns and that the frequency and intensity of such episodes have major implications for predictive models of species distribution and ecosystem structure, which are largely based on gradual warming trends.

  4. Tree-ring responses to extreme climate events as benchmarks for terrestrial dynamic vegetation models

    Directory of Open Access Journals (Sweden)

    A. Rammig

    2014-02-01

    Full Text Available Climate extremes can trigger exceptional responses in terrestrial ecosystems, for instance by altering growth or mortality rates. Effects of this kind are often manifested in reductions of the local net primary production (NPP. Investigating a set of European long-term data on annual radial tree growth confirms this pattern: we find that 53% of tree ring width (TRW indices are below one standard deviation, and up to 16% of the TRW values are below two standard deviations in years with extremely high temperatures and low precipitation. Based on these findings we investigate if climate driven patterns in long-term tree growth data may serve as benchmarks for state-of-the-art dynamic vegetation models such as LPJmL. The model simulates NPP but not explicitly the radial tree ring growth, hence requiring a generic method to ensure an objective comparison. Here we propose an analysis scheme that quantifies the coincidence rate of climate extremes with some biotic responses (here TRW or simulated NPP. We find that the reduction in tree-ring width during drought extremes is lower than the corresponding reduction of simulated NPP. We identify ten extreme years during the 20th century in which both, model and measurements indicate high coincidence rates across Europe. However, we detect substantial regional differences in simulated and observed responses to extreme events. One explanation for this discrepancy could be that the tree-ring data have preferentially been sampled at more climatically stressed sites. The model-data difference is amplified by the fact that dynamic vegetation models are designed to simulate mean ecosystem responses at landscape or regional scale. However, we find that both model-data and measurements display carry-over effects from the previous year. We conclude that using radial tree growth is a good basis for generic model-benchmarks if the data are analyzed by scale-free measures such as coincidence analysis. Our study shows

  5. Large-scale Agroecosytem's Resiliency to Extreme Hydrometeorological and Climate Extreme Events in the Missouri River Basin

    Science.gov (United States)

    Munoz-Arriola, F.; Smith, K.; Corzo, G.; Chacon, J.; Carrillo-Cruz, C.

    2015-12-01

    A major challenge for water, energy and food security relies on the capability of agroecosyststems and ecosystems to adapt to a changing climate and land use changes. The interdependency of these forcings, understood through our ability to monitor and model processes across scales, indicate the "depth" of their impact on agroecosystems and ecosystems, and consequently our ability to predict the system's ability to return to a "normal" state. We are particularly interested in explore two questions: (1) how hydrometeorological and climate extreme events (HCEs) affect sub-seasonal to interannual changes in evapotranspiration and soil moisture? And (2) how agroecosystems recover from the effect of such events. To address those questions we use the land surface hydrologic Variable Infiltration Capacity (VIC) model and the Moderate Resolution Imaging Spectrometer-Leaf Area Index (MODIS-LAI) over two time spans (1950-2013 using a seasonal fixed LAI cycle) and 2001-2013 (an 8-day MODIS-LAI). VIC is forced by daily/16th degree resolution precipitation, minimum and maximum temperature, and wind speed. In this large-scale experiment, resiliency is defined by the capacity of a particular agroecosystem, represented by a grid cell's ET, SM, and LAI to return to a historical average. This broad, yet simplistic definition will contribute to identify the possible components and their scales involved in agroecosystems and ecosystems capacity to adapt to the incidence of HCEs and technologies used to intensify agriculture and diversify their use for food and energy production. Preliminary results show that dynamical changes in land use, tracked by MODIS data, require larger time spans to address properly the influence of technologic improvements in crop production as well as the competition for land for biofuel vs. food production. On the other hand, fixed seasonal changes in land use allow us just to identify hydrologic changes mainly due to climate variability.

  6. Assessment of flood Response Characteristics to Urbanization and extreme flood events-Typhoons at Cheongju, Chungbuk

    Science.gov (United States)

    Chang, HyungJoon; Lee, Hyosang; Hwang, Myunggyu; Jang, Sukhwan

    2016-04-01

    The changes of land use influence on the flood characteristics, which depend on rainfall runoff procedures in the catchment. This study assesses the changes of flood characteristics due to land use changes between 1997 and 2012. The catchment model (HEC-HMS) is calibrated with flood events of 1990's and 2000's respectively, then the design rainfall of 100, 200, 500year return period are applied to this model, which represent the catchment in 1990's and 2000's, to assess the flood peaks. Then the extreme flood events (i.e., 6 typhoon events) are applied to assess the flood responses. The results of comparison between 1990's and 2000's show that the flood peak and level of 2000's are increasing and time to peak of 2000's is decreasing comparing to those of 1990's :3% to 78% increase in flood peak, 3% in flood level and 10.2% to 16% decrease in time to peak in 100year return period flood. It is due to decreasing of the farmland area (2.18%), mountainous area (8.88%), and increasing of the urbanization of the area (5.86%). This study also estimates the responses to extreme flood events. The results of 2000's show that the increasing of the flood peak and time to peak comparing to 1990's. It indicates that the extreme rainfall is more responsible at unurbanized catchment ( 2000's), which resulting with a 11% increasing of the peak volume. Acknowledgement This research was supported by a grant (11-TI-C06) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

  7. Extreme climatic events: reducing ecological and social systems vulnerabilities; Evenements climatiques extremes: reduire les vulnerabilites des systemes ecologiques et sociaux

    Energy Technology Data Exchange (ETDEWEB)

    Decamps, H.; Amatore, C.; Bach, J.F.; Baccelli, F.; Balian, R.; Carpentier, A.; Charnay, P.; Cuzin, F.; Davier, M.; Dercourt, J.; Dumas, C.; Encrenaz, P.; Jeannerod, M.; Kahane, J.P.; Meunier, B.; Rebut, P.H.; Salencon, J.; Spitz, E.; Suquet, P.; Taquet, P.; Valleron, A.J.; Yoccoz, J.C.; Chapron, J.Y.; Fanon, J.; Andre, J.C.; Auger, P.; Bourrelier, P.H.; Combes, C.; Derrida, B.; Laubier, L.; Laval, K.; Le Maho, Y.; Marsily, G. De; Petit, M.; Schmidt-Laine, C.; Birot, Y.; Peyron, J.L.; Seguin, B.; Barles, S.; Besancenot, J.P.; Michel-Kerjan, E.; Hallegatte, S.; Dumas, P.; Ancey, V.; Requier-Desjardins, M.; Ducharnes, A.; Ciais, P.; Peylin, P.; Kaniewski, D.; Van Campo, E.; Planton, S.; Manuguerra, J.C.; Le Bars, Y.; Lagadec, P.; Kessler, D.; Pontikis, C.; Nussbaum, R.

    2010-07-01

    The Earth has to face more and more devastating extreme events. Between 1970 and 2009, at the worldwide scale, the 25 most costly catastrophes all took place after 1987, and for more than half of them after 2001. Among these 25 catastrophes, 23 were linked to climate conditions. France was not spared: the December 1999 storms led to 88 deaths, deprived 3.5 million households of electricity and costed more than 9 billion euros. The 2003 heat wave led to about 15000 supernumerary deaths between August 1 and August 20. The recent Xynthia storm, with its flood barrier ruptures, provoked 53 deaths in addition to many other tragedies that took place in areas liable to flooding. In the present day context of climate change, we know that we must be prepared to even more dangerous events, sometimes unexpected before. These events can have amplified effects because of the urban development, the overpopulation of coastal areas and the anthropization of natural environments. They represent real 'poverty traps' for the poorest countries of the Earth. The anticipation need is real but is our country ready to answer it? Does it have a sufficient contribution to international actions aiming at reducing risks? Is his scientific information suitable? France is not less vulnerable than other countries. It must reinforce its prevention, its response and resilience capacities in the framework of integrated policies of catastrophes risk management as well as in the framework of climate change adaptation plans. This reinforcement supposes the development of vigilance systems with a better risk coverage and benefiting by the advances gained in the meteorology and health domains. It supposes a town and country planning allowing to improve the viability of ecological and social systems - in particular by protecting their diversity. Finally, this reinforcement requires inciting financial coverage solutions for catastrophes prevention and for their management once they have taken

  8. Extreme fluxes in solar energetic particle events: Methodological and physical limitations

    International Nuclear Information System (INIS)

    In this study, all available data on the largest solar proton events (SPEs), or extreme solar energetic particle (SEP) events, for the period from 1561 up to now are analyzed. Under consideration are the observational, methodological and physical problems of energy-spectrum presentation for SEP fluxes (fluences) near the Earth's orbit. Special attention is paid to the study of the distribution function for extreme fluences of SEPs by their sizes. The authors present advances in at least three aspects: 1) a form of the distribution function that was previously obtained from the data for three cycles of solar activity has been completely confirmed by the data for 41 solar cycles; 2) early estimates of extremely large fluences in the past have been critically revised, and their values were found to be overestimated; and 3) extremely large SEP fluxes are shown to obey a probabilistic distribution, so the concept of an “upper limit flux” does not carry any strict physical sense although it serves as an important empirical restriction. SEP fluxes may only be characterized by the relative probabilities of their appearance, and there is a sharp break in the spectrum in the range of large fluences (or low probabilities). It is emphasized that modern observational data and methods of investigation do not allow, for the present, the precise resolution of the problem of the spectrum break or the estimation of the maximum potentialities of solar accelerator(s). This limitation considerably restricts the extrapolation of the obtained results to the past and future for application to the epochs with different levels of solar activity. - Highlights: • All available data on the largest solar proton events (SPEs) are analyzed. • Distribution function obtained for 3 last cycles is confirmed for 41 solar cycles. • Estimates of extremely large fluences in the past are found to be overestimated. • Extremely large SEP fluxes are shown to obey a probabilistic distribution.

  9. Quantifying the US Crop Yield in Response to Extreme Climatic Events from 1948 to 2013

    Science.gov (United States)

    Jin, Z.; Zhuang, Q.

    2014-12-01

    The increasingly frequent and severe extreme climatic events (ECEs) under climate changes will negatively affect crop productivity and threat the global food security. Reliable forecast of crop yields response to those ECEs is a prerequisite for developing strategies on agricultural risk management. However, the progress of quantifying such responses with ecosystem models has been slow. In this study, we first review existing algorithms of yields response to ECEs among major crops (i.e., Corn, Wheat and Soybean) for the United States from a set of process-based crop models. These algorithms are aggregated into four categories of ECEs: drought, heavy precipitation, extreme heat, and frost. Species-specific ECEs thresholds as tipping point of crop yield response curve are examined. Four constraint scalar functions derived for each category of ECEs are then added to an agricultural ecosystem model, CLM-AG, respectively. The revised model is driven by NCEP/NCAR reanalysis data from 1948 to 2013 to estimate the US major crop yields, and then evaluated with county-level yield statistics from the National Agricultural Statistics Service (NASS). We also include MODIS NPP product as a reference for the period 2001-2013. Our study will help to identify gaps in capturing yield response to ECEs with contemporary crop models, and provide a guide on developing the new generation of crop models to account for the effects of more future extreme climate events.

  10. Granularity and textural analysis as a proxy for extreme wave events in southeast coast of India

    Indian Academy of Sciences (India)

    C S Vijaya Lakshmi; P Srinivasan; S G N Murthy; Deshraj Trivedi; Rajesh R Nair

    2010-06-01

    Extreme wave events of 1000 and 1500 years (radiocarbon ages) have been recently reported in Mahabalipuram region, southeast coast of India. Subsequently, we carried out extensive sedimentological analysis in regions covering a total lateral coverage of 12 km with a new archeological site as the central portion of the study area. Twelve trenches in shore normal profiles exhibit landward thinning sequences as well as upward fining sequences confirming with the global signatures of extreme wave events. The sediment size ranges from fine-to-medium and moderately well sorted-to-well sorted, and exhibit positive skewness with platykurtic-to-leptokurtic nature. We now propose the abrupt winnowing or back and forth motion including unidirectional transport of these deposited sediments, which results in positive skewness. Textural analyses derived from scanning electron microscope studies (SEM) demonstrate the alteration produced, in the ilmenite mineral with vivid presence of pits and crescents with deformation observed on the surface due to extreme wave activities. This is further confirmed with the predominance of high-density mineral such as magnetite (5.2) and other heavy minerals in these deposits inferred the high-intensity of the reworking process of the beach shelf sediments.

  11. Vegetation response to extreme climate events on the Mongolian Plateau from 2000 to 2010

    International Nuclear Information System (INIS)

    Climate change has led to more frequent extreme winters (aka, dzud) and summer droughts on the Mongolian Plateau during the last decade. Among these events, the 2000–2002 combined summer drought–dzud and 2010 dzud were the most severe on vegetation. We examined the vegetation response to these extremes through the past decade across the Mongolian Plateau as compared to decadal means. We first assessed the severity and extent of drought using the Tropical Rainfall Measuring Mission (TRMM) precipitation data and the Palmer drought severity index (PDSI). We then examined the effects of drought by mapping anomalies in vegetation indices (EVI, EVI2) and land surface temperature derived from MODIS and AVHRR for the period of 2000–2010. We found that the standardized anomalies of vegetation indices exhibited positively skewed frequency distributions in dry years, which were more common for the desert biome than for grasslands. For the desert biome, the dry years (2000–2001, 2005 and 2009) were characterized by negative anomalies with peak values between −1.5 and −0.5 and were statistically different (P 2 = 65 and 60, p 2 = 53, p < 0.05). Our results showed significant differences in the responses to extreme climatic events (summer drought and dzud) between the desert and grassland biomes on the Plateau. (letter)

  12. An extreme internal solitary wave event observed in the northern South China Sea

    Science.gov (United States)

    Huang, Xiaodong; Chen, Zhaohui; Zhao, Wei; Zhang, Zhiwei; Zhou, Chun; Yang, Qingxuan; Tian, Jiwei

    2016-01-01

    With characteristics of large amplitude and strong current, internal solitary wave (ISW) is a major hazard to marine engineering and submarine navigation; it also has significant impacts on marine ecosystems and fishery activity. Among the world oceans, ISWs are particular active in the northern South China Sea (SCS). In this spirit, the SCS Internal Wave Experiment has been conducted since March 2010 using subsurface mooring array. Here, we report an extreme ISW captured on 4 December 2013 with a maximum amplitude of 240 m and a peak westward current velocity of 2.55 m/s. To the authors’ best knowledge, this is the strongest ISW of the world oceans on record. Full-depth measurements also revealed notable impacts of the extreme ISW on deep-ocean currents and thermal structures. Concurrent mooring measurements near Batan Island showed that the powerful semidiurnal internal tide generation in the Luzon Strait was likely responsible for the occurrence of the extreme ISW event. Based on the HYCOM data-assimilation product, we speculate that the strong stratification around Batan Island related to the strengthening Kuroshio may have contributed to the formation of the extreme ISW. PMID:27444063

  13. Extreme weather event in spring 2013 delayed breeding time of Great Tit and Blue Tit.

    Science.gov (United States)

    Glądalski, Michał; Bańbura, Mirosława; Kaliński, Adam; Markowski, Marcin; Skwarska, Joanna; Wawrzyniak, Jarosław; Zieliński, Piotr; Bańbura, Jerzy

    2014-12-01

    The impact of climatic changes on life cycles by re-scheduling the timing of reproduction is an important topic in studies of biodiversity. Global warming causes and will probably cause in the future not only raising temperatures but also an increasing frequency of extreme weather events. In 2013, the winter in central and north Europe ended late, with low temperatures and long-retained snow cover--this extreme weather phenomenon acted in opposition to the increasing temperature trend. In 2013, thermal conditions measured by the warmth sum in the period 15 March–15 April, a critical time for early breeding passerines, went far beyond the range of the warmth sums for at least 40 preceding years. Regardless of what was the reason for the extreme early spring 2013 and assuming that there is a potential for more atypical years because of climate change, we should look closely at every extreme phenomenon and its consequences for the phenology of organisms. In this paper, we report that the prolonged occurrence of winter conditions during the time that is crucial for Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) reproduction caused a substantial delay in the onset of egg laying in comparison with typical springs. PMID:24659171

  14. Extreme meteorological events in nuclear power plant siting, excluding tropical cyclones

    International Nuclear Information System (INIS)

    This Safety Guide deals with the extremes of meteorological variables and the extreme meteorological phenomena in accordance with the general criteria of the Code. The Guide outlines a procedure based on the following steps: (1) The meteorological phenomena and variables are described and classified, according to their effects on safety. (2) Data sources are identified, and data are collected. (3) Meteorological variables such as air temperature are analysed to determine their design bases; and the design basis event in case of phenomena such as the design basis tornado is identified. (4) As appropriate, the design basis value for the variable, or the design basis for the phenomena (such as pressure drop and maximum wind speed of the design basis tornado), is defined. In the following sections, the general procedure for evaluating the design bases of extreme meteorological variables and phenomena is outlined. The procedure is then presented in detail for each variable or phenomenon considered. The variables characterizing the meteorological environment dealt with in this Guide are wind speed, atmospheric precipitation, and temperature. The extreme meteorological phenomena discussed here are the tornado and, briefly, the tropical cyclone, which is discussed more extensively in the Safety Guide on Design Basis Tropical Cyclone for Nuclear Power Plants (IAEA Safety Series No. 50-SG-S11B)

  15. An extreme internal solitary wave event observed in the northern South China Sea

    Science.gov (United States)

    Huang, Xiaodong; Chen, Zhaohui; Zhao, Wei; Zhang, Zhiwei; Zhou, Chun; Yang, Qingxuan; Tian, Jiwei

    2016-07-01

    With characteristics of large amplitude and strong current, internal solitary wave (ISW) is a major hazard to marine engineering and submarine navigation; it also has significant impacts on marine ecosystems and fishery activity. Among the world oceans, ISWs are particular active in the northern South China Sea (SCS). In this spirit, the SCS Internal Wave Experiment has been conducted since March 2010 using subsurface mooring array. Here, we report an extreme ISW captured on 4 December 2013 with a maximum amplitude of 240 m and a peak westward current velocity of 2.55 m/s. To the authors’ best knowledge, this is the strongest ISW of the world oceans on record. Full-depth measurements also revealed notable impacts of the extreme ISW on deep-ocean currents and thermal structures. Concurrent mooring measurements near Batan Island showed that the powerful semidiurnal internal tide generation in the Luzon Strait was likely responsible for the occurrence of the extreme ISW event. Based on the HYCOM data-assimilation product, we speculate that the strong stratification around Batan Island related to the strengthening Kuroshio may have contributed to the formation of the extreme ISW.

  16. Extreme external events in the design and assessment of nuclear power plants

    International Nuclear Information System (INIS)

    The analysis of feedback experience from the operation of nuclear power plants (NPPs) in the past 20 years shows few cases of degradation of the plant safety initiated by external events. However, when these have occurred, the consequences have been serious, involving challenges to the defence in depth of the plant. Part of the problem involves the definition of the design basis parameters for some scenarios and differences among regulators on the methods for the protection of operational NPPs in relation to external events. This results in different engineering practices in Member States for the siting and design of NPPs. In the framework of the present revision of the IAEA safety standards on siting and design of NPPs, many initiatives have been implemented by the IAEA in recent years aimed at a systematic analysis of engineering practices in Member States. The most recent event in this connection was a Technical Committee Meeting (TCM) on Structural Safety of NPPs in Relation to Extreme External Loads, organized with the specific objective of evaluating the state of the art of NPP design in relation to external events. Such an analysis provided a technical background for the development of a common technical basis for an integrated approach in site evaluation, design and operation in relation to extreme external events. The scope included new and existing plants, as they are required to meet the same general safety principles, in spite of their peculiarities. The objective of this publication is to provide a technical background to drive regulators, plant owners and designers in the definition of a consistent strategy in selected safety issues on site evaluation, design and operation in relation to extreme external events. This publication is also of support to the IAEA in the development of safety standards since many Safety Guides dealing with related topics are under periodic review. Four major tasks were identified to comply with these general objectives

  17. Ecological Responses to Extreme Flooding Events: A Case Study with a Reintroduced Bird.

    Science.gov (United States)

    Soriano-Redondo, Andrea; Bearhop, Stuart; Cleasby, Ian R; Lock, Leigh; Votier, Stephen C; Hilton, Geoff M

    2016-01-01

    In recent years numerous studies have documented the effects of a changing climate on the world's biodiversity. Although extreme weather events are predicted to increase in frequency and intensity and are challenging to organisms, there are few quantitative observations on the survival, behaviour and energy expenditure of animals during such events. We provide the first data on activity and energy expenditure of birds, Eurasian cranes Grus grus, during the winter of 2013-14, which saw the most severe floods in SW England in over 200 years. We fitted 23 cranes with telemetry devices and used remote sensing data to model flood dynamics during three consecutive winters (2012-2015). Our results show that during the acute phase of the 2013-14 floods, potential feeding areas decreased dramatically and cranes restricted their activity to a small partially unflooded area. They also increased energy expenditure (+15%) as they increased their foraging activity and reduced resting time. Survival did not decline in 2013-14, indicating that even though extreme climatic events strongly affected time-energy budgets, behavioural plasticity alleviated any potential impact on fitness. However under climate change scenarios such challenges may not be sustainable over longer periods and potentially could increase species vulnerability. PMID:27345214

  18. Ecological Responses to Extreme Flooding Events: A Case Study with a Reintroduced Bird

    Science.gov (United States)

    Soriano-Redondo, Andrea; Bearhop, Stuart; Cleasby, Ian R.; Lock, Leigh; Votier, Stephen C.; Hilton, Geoff M.

    2016-01-01

    In recent years numerous studies have documented the effects of a changing climate on the world’s biodiversity. Although extreme weather events are predicted to increase in frequency and intensity and are challenging to organisms, there are few quantitative observations on the survival, behaviour and energy expenditure of animals during such events. We provide the first data on activity and energy expenditure of birds, Eurasian cranes Grus grus, during the winter of 2013–14, which saw the most severe floods in SW England in over 200 years. We fitted 23 cranes with telemetry devices and used remote sensing data to model flood dynamics during three consecutive winters (2012–2015). Our results show that during the acute phase of the 2013–14 floods, potential feeding areas decreased dramatically and cranes restricted their activity to a small partially unflooded area. They also increased energy expenditure (+15%) as they increased their foraging activity and reduced resting time. Survival did not decline in 2013–14, indicating that even though extreme climatic events strongly affected time-energy budgets, behavioural plasticity alleviated any potential impact on fitness. However under climate change scenarios such challenges may not be sustainable over longer periods and potentially could increase species vulnerability. PMID:27345214

  19. Evaluating the extreme precipitation events using a mesoscale atmosphere model and satellite based precipitation product

    Directory of Open Access Journals (Sweden)

    I. Yucel

    2013-12-01

    Full Text Available Quantitative precipitation estimates are obtained with more uncertainty under the influence of changing climate variability and complex topography from numerical weather prediction (NWP models. On the other hand, hydrologic model simulations depend heavily on the availability of reliable precipitation estimates. Difficulties in estimating precipitation impose an important limitation on the possibility and reliability of hydrologic forecasting and early warning systems. This study examines the performance of the Weather Research and Forecasting (WRF model and the Multi Precipitation Estimates (MPE algorithm in producing the temporal and spatial characteristics of the number of extreme precipitation events observed in the West Black Sea Region of Turkey. Precipitations derived from WRF model with and without three-dimensional variational (3-DVAR data assimilation scheme and MPE algorithm at high spatial resolution (4 km are compared with gauge precipitation. WRF-derived precipitation showed capabilities in capturing the timing of precipitation extremes and in some extent the spatial distribution and magnitude of the heavy rainfall events wheras MPE showed relatively weak skills in these aspects. WRF skills in estimating such precipitation characteristics are enhanced with the application of 3-DVAR scheme. Direct impact of data assimilation on WRF precipitation reached to 12% and at some points there exists quantitative match for heavy rainfall events, which are critical for hydrological forecast.

  20. Application of a 2D Hydrodynamic Model for Assessing Flood Risk from Extreme Storm Events

    Directory of Open Access Journals (Sweden)

    Sohan Ghimire

    2013-11-01

    Full Text Available In the wake of increasing flood disasters, there is an increasing use of flood inundation models to assess risks and impacts at different temporal and spatial scales. Assessing the impacts of extreme climatic rainfall events will require developing design rainfall profiles to represent rainfall under different conditions. Rainfall profiles of different return periods were developed using the Flood Estimation Handbook (FEH methodology for a small rural catchment of Scotland, to assess flood risks at a catchment scale. Rainfall induced runoff flows were estimated based on a set of catchment characteristics. The channel and floodplain flows were modelled using a two-dimensional hydrodynamic model-TUFLOW. The main channel was represented by a one-dimensional linear channel based on surveyed data and the floodplain topography, was represented by a digital terrain model based on Light Detection and Ranging (LiDAR. A range of hydrological events with different return periods are simulated. Results show that many residential houses and an extensive area of agricultural land are at risk of flooding from extreme events such as a 1 in 100 year flood.

  1. The differential effects of increasing frequency and magnitude of extreme events on coral populations.

    Science.gov (United States)

    Fabina, Nicholas S; Baskett, Marissa L; Gross, Kevin

    2015-09-01

    Extreme events, which have profound ecological consequences, are changing in both frequency and magnitude with climate change. Because extreme temperatures induce coral bleaching, we can explore the relative impacts of changes in frequency and magnitude of high temperature events on coral reefs. Here, we combined climate projections and a dynamic population model to determine how changing bleaching regimes influence coral persistence. We additionally explored how coral traits and competition with macroalgae mediate changes in bleaching regimes. Our results predict that severe bleaching events reduce coral persistence more than frequent bleaching. Corals with low adult mortality and high growth rates are successful when bleaching is mild, but bleaching resistance is necessary to persist when bleaching is severe, regardless of frequency. The existence of macroalgae-dominated stable states reduces coral persistence and changes the relative importance of coral traits. Building on previous studies, our results predict that management efforts may need to prioritize protection of "weaker" corals with high adult mortality when bleaching is mild, and protection of "stronger" corals with high bleaching resistance when bleaching is severe. In summary, future reef projections and conservation targets depend on both local bleaching regimes and biodiversity. PMID:26552262

  2. Application of a Coupled WRF-Hydro Model for Extreme Flood Events in the Mediterranean Basins

    Science.gov (United States)

    Fredj, Erick; Givati, Amir

    2015-04-01

    More accurate simulation of precipitation and streamflow is a challenge that can be addressed by using the Weather Research and Forecasting Model (WRF) in conjunction with the hydrological model coupling extension package (WRF-Hydro).This is demonstrated for the country of Israel and surrounding regions. Simulations from the coupled WRF/WRF-Hydro system were verified against measurements from rain gauges and hydrometric stations in the domain for the 2012-2013 and 2013-2014 winters (wet seasons). These periods were characterized by many punctuated hydrometeorological and hydroclimatic events, including both severe drought and extreme floods events. The WRF model simulations were initialized with 0.5 degree NOAA/NCEP GFS model data. The model domain was set up with 3 domains, up to 3km grid spacing resolution. The model configuration used here constitutes a fully distributed, 3-dimensional, variably-saturated surface and subsurface flow model. Application of terrain routing and, subsequently, channel and reservoir routing functions, to the uni-dimensional NOAA land surface model was motivated by the need to account for increased complexity in land surface states and fluxes and to provide a more physically-realistic conceptualization of terrestrial hydrologic processes. The simulation results indicated a good agreement with actual peak discharges for extreme flood events and for full hydrographs. Specifically the coupled WRF/WRF-Hydro model as configured in this study shows improvement in simulated precipitation over one way WRF precipitation simulations. The correlation between the observed and the simulated precipitation using the fully coupled WRF/WRF-Hydro system was higher than the standalone WRF model, especially for convective precipitation events that affect arid regions in the domain. The results suggest that the coupled WRF/WRF-Hydro system has potential for flood forecasting and flood warning purposes at 0-72 hour lead times for large cool season storm

  3. Forecasting extreme events in collective dynamics: an analytic signal approach to detecting discrete scale invariance

    CERN Document Server

    Viswanathan, G M

    2006-01-01

    A challenging problem in physics concerns the possibility of forecasting rare but extreme phenomena such as large earthquakes, financial market crashes, and material rupture. A promising line of research involves the early detection of precursory log-periodic oscillations to help forecast extreme events in collective phenomena where discrete scale invariance plays an important role. Here I investigate two distinct approaches towards the general problem of how to detect log-periodic oscillations in arbitrary time series without prior knowledge of the location of the moveable singularity. I first show that the problem has a definite solution in Fourier space, however the technique involved requires an unrealistically large signal to noise ratio. I then show that the quadrature signal obtained via analytic continuation onto the imaginary axis, using the Hilbert transform, necessarily retains the log-periodicities found in the original signal. This finding allows the development of a new method of detecting log-p...

  4. Complex networks identify spatial patterns of extreme rainfall events of the South American Monsoon System

    Science.gov (United States)

    Boers, Niklas; Bookhagen, Bodo; Marwan, Norbert; Kurths, Jürgen; Marengo, José

    2013-08-01

    We investigate the spatial characteristics of extreme rainfall synchronicity of the South American Monsoon System (SAMS) by means of Complex Networks (CN). By introducing a new combination of CN measures and interpreting it in a climatic context, we investigate climatic linkages and classify the spatial characteristics of extreme rainfall synchronicity. Although our approach is based on only one variable (rainfall), it reveals the most important features of the SAMS, such as the main moisture pathways, areas with frequent development of Mesoscale Convective Systems (MCS), and the major convergence zones. In addition, our results reveal substantial differences between the spatial structures of rainfall synchronicity above the 90th and above the 95th percentiles. Most notably, events above the 95th percentile contribute stronger to MCS in the La Plata Basin.

  5. Characteristics of extreme dust events observed over two urban areas in Iran

    Indian Academy of Sciences (India)

    Abbas-Ali A Bidokhti; Maryam Gharaylou; Nafiseh Pegahfar; Samaneh Sabetghadam; Maryam Rezazadeh

    2016-03-01

    Determination of dust loading in the atmosphere is important not only from the public health point of view, but also for regional climate changes. The present study focuses on the characteristics of two major dust events for two urban areas in Iran, Kermanshah and Tehran, over the period of 4 years from 2006 to 2009. To detect extreme dust outbreaks, various datasets including synoptic data, dust concentration, reanalysis data and numerical results of WRF and HYSPLIT models were used. The weather maps demonstrate that for these events dusts are mainly generated when wind velocity is high and humidity islow in the lower troposphere and the region is under the influence of a thermal low. The event lasts until the atmospheric stability prevails and the surface wind speed weakens. The thermal low nature of the synoptic conditions of these major events is also responsible for deep boundary layer development with its thermals affecting the vertical dust flux over the region. Trajectory studies show that the dust events originated from deserts in Iraq and Syria and transported towards Iran. The main distinction between the two types of mobilizations seems to affect the dust concentrations in the Tehran urban area.

  6. Characteristics of extreme dust events observed over two urban areas in Iran

    Science.gov (United States)

    Bidokhti, Abbas-Ali A.; Gharaylou, Maryam; Pegahfar, Nafiseh; Sabetghadam, Samaneh; Rezazadeh, Maryam

    2016-03-01

    Determination of dust loading in the atmosphere is important not only from the public health point of view, but also for regional climate changes. The present study focuses on the characteristics of two major dust events for two urban areas in Iran, Kermanshah and Tehran, over the period of 4 years from 2006 to 2009. To detect extreme dust outbreaks, various datasets including synoptic data, dust concentration, reanalysis data and numerical results of WRF and HYSPLIT models were used. The weather maps demonstrate that for these events dusts are mainly generated when wind velocity is high and humidity is low in the lower troposphere and the region is under the influence of a thermal low. The event lasts until the atmospheric stability prevails and the surface wind speed weakens. The thermal low nature of the synoptic conditions of these major events is also responsible for deep boundary layer development with its thermals affecting the vertical dust flux over the region. Trajectory studies show that the dust events originated from deserts in Iraq and Syria and transported towards Iran. The main distinction between the two types of mobilizations seems to affect the dust concentrations in the Tehran urban area.

  7. Impacts of extreme events of drought and flood on local communities of Amazon basin

    Science.gov (United States)

    Borma, L. D.; Roballo, S.; Zauner, M.; Nascimento, V. F.

    2013-05-01

    The analysis of drought events of 1997/98, 2005 and 2010 in terms of discharge anomalies in the Amazon region confirmed previous findings, such as: a) the influence of the El Niño in more than one hydrological year; b) the increase of the influence of the Atlantic Multidecadal Oscillation of 1998, 2005 and 2010 drought events; c) the low levels of discharge observed in the 2010 drought are attributed to the association of discharge anomalies of the northern and southern tributaries of the Amazon river, and d) the 2010 drought lasted around 1 month (August to November) more than the other drought events analized here. The riverine communities located along the river banks of Solimões/Amazonas suit their economic activities to the oscillation of the water level. In general, low water periods favor the access to important sources of food such as fish and livestock, still allowing crop cultivation on fertile agricultural areas of the floodplain. Conversely, periods of drought increases the difficulties of transport and drinking water supply. During the high water, access to the main food supply (described above) are greatly hampered. However, the floods are recognized as an importance process of natural fertilization. Thus, despite the political, social and economic shortcomings, the local community has, since the pre-colonial period, learned to get the best of each season, providing local, regional and national markets with varzea products. During periods of extreme weather, however, the advantages of each season appear to be reduced, and the drawbacks increased. In fact, during flooding extremes, the access to primary sources of food is hampered by a long period of time and families find themselves forced to leave their homes, eventually losing them. Analysis of flow data to the extreme flooding of 2009, indicate a period of about 6 months of positive anomalies discharge (occurring mainly during high water). At the same time, Civil Defense data points to a

  8. About offshore resource assessment with floating lidars with special respect to turbulence and extreme events

    International Nuclear Information System (INIS)

    Offshore resource assessment with lidars on floating platforms is a flexible and particularly cost-effective alternative to the conventional meteorological mast solution, that is considered as onshore state-of-the-art transferred to offshore sites, and may enable better and more complete wind resource assessments for the growing offshore wind sector. Wind lidar technology, and remote sensing in general, has already been proven to be a very promising technology for resource assessment and power performance testing onshore. For offshore applications and on floating platforms in particular, the motions from the floating base have to be considered in addition, affecting the wind measurements significantly and causing systematic measurement errors. We have studied the motions and the corresponding influences on lidar measurements generated by different possible offshore platforms – vessels or buoys – both in detailed simulations as well as first validation experiments. In addition to this, we have developed motion compensation algorithms that allow to correct the affected measurements and retrieve the undisturbed wind data. The motions considered and studied comprise rotations as well as translations in all six degrees of freedom. For the evaluation of the motion-affected and corrected wind data in this paper, special attention is paid to the measurement of turbulence as well as extreme wind events. The research question to be answered is if a lidar device placed on a floating platform is capable of measuring more or less the same statistics of extreme wind events as a fixed lidar device. Quantities to be investigated are: the turbulence intensity as well as the statistics of maximum wind speed values within a 10-min period, but also wind speed increments on different time scales. At this, obviously two issues are to be discussed – the influence of the lidar measurement principle on the recording of extreme wind events, and the additional impact of the

  9. Cross-timescale Interference and Rainfall Extreme Events in South Eastern South America

    Science.gov (United States)

    Munoz, Angel G.

    The physical mechanisms and predictability associated with extreme daily rainfall in South East South America (SESA) are investigated for the December-February season. Through a k-mean analysis, a robust set of daily circulation regimes is identified and then it is used to link the frequency of rainfall extreme events with large-scale potential predictors at subseasonal-to-seasonal scales. This basic set of daily circulation regimes is related to the continental and oceanic phases of the South Atlantic Convergence Zone (SACZ) and wave train patterns superimposed on the Southern Hemisphere Polar Jet. Some of these recurrent synoptic circulation types are conducive to extreme rainfall events in the region through synoptic control of different meso-scale physical features and, at the same time, are influenced by climate phenomena that could be used as sources of potential predictability. Extremely high rainfall (as measured by the 95th- and 99th-percentiles) is preferentially associated with two of these weather types, which are characterized by moisture advection intrusions from lower latitudes and the Pacific; another three weather types, characterized by above-normal moisture advection toward lower latitudes or the Andes, are preferentially associated with dry days (days with no rain). The analysis permits the identification of several subseasonal-to-seasonal scale potential predictors that modulate the occurrence of circulation regimes conducive to extreme rainfall events in SESA. It is conjectured that a cross-timescale interference between the different climate drivers improves the predictive skill of extreme precipitation in the region. The potential and real predictive skill of the frequency of extreme rainfall is then evaluated, finding evidence indicating that mechanisms of climate variability at one timescale contribute to the predictability at another scale, i.e., taking into account the interference of different potential sources of predictability at

  10. Daily precipitation extreme events for the Iberian Peninsula and its association with Atmospheric Rivers

    Science.gov (United States)

    Ramos, Alexandre M.; Trigo, Ricardo M.; Liberato, Margarida LR

    2014-05-01

    Extreme precipitation events in the Iberian Peninsula during the extended winter months have major socio-economic impacts such as floods, landslides, extensive property damage and life losses. These events are usually associated with low pressure systems with Atlantic origin, although some extreme events in summer/autumn months can be linked to Mediterranean low pressure systems. Quite often these events are evaluated on a casuistic base and making use of data from relatively few stations. An objective method for ranking daily precipitation events is presented here based on the extensive use of the most comprehensive database of daily gridded precipitation available for the Iberian Peninsula (IB02) and spanning from 1950 to 2008, with a resolution of 0.2° (approximately 16 x 22 km at latitude 40°N), for a total of 1673 pixels. This database is based on a dense network of rain gauges, combining two national data sets, 'Spain02' for peninsular Spain and Balearic islands, and 'PT02' for mainland Portugal, with a total of more than two thousand stations over Spain and four hundred stations over Portugal, all quality-controlled and homogenized. Through this objective method for ranking daily precipitation events the magnitude of an event is obtained after considering the area affected as well as its intensity in every grid point and taking into account the daily precipitation normalised departure from climatology. Different precipitation rankings are presented considering the entire Iberian Peninsula, Portugal and also the six largest river basins in the Iberian Peninsula. Atmospheric Rivers (AR) are the water vapour (WV) core section of the broader warm conveyor belt occurring over the oceans along the warm sector of extra-tropical cyclones. They are usually W-E oriented steered by pre-frontal low level jets along the trailing cold front and subsequently feed the precipitation in the extra-tropical cyclones. They are relatively narrow regions of concentrated WV

  11. Excitable chaotic pulses exhibiting extreme events statistics in an opto-radiofrequency oscillator

    CERN Document Server

    Romanelli, Marco; Erneux, Thomas; Vallet, Marc

    2015-01-01

    We report theoretical and experimental evidence of a new kind of excitability in an opto-radiofrequency oscillator based on a self-injected dual-frequency laser. At variance with previous reports on injected lasers, the excitable pulses are not accompanied by phase slips, and thus cannot be explained by the universal mechanism described by Adler approximation. Another original feature of our system is that the excitable response involves a bifurcation towards a chaotic attractor. Furthermore, we show that this excitability mechanism generates a stochastic process characterized by a non-gaussian statistics, and exhibiting extreme events.

  12. Statistics of extreme gravitational lensing events; 1, the zero shear case

    CERN Document Server

    Wang, Y; Wang, Yun; Turner, Edwin L

    1996-01-01

    For a given source and lens pair, there is a thin on-axis tube volume behind the lens in which the radiation flux is greatly increased due to gravitational lensing. Any objects (such as dust grains) which pass through such a thin tube will experience strong bursts of radiation, i.e., Extreme Gravitational Lensing Events (EGLE). We study the physics and statistics of EGLE for the case in which finite source size is more important than shear. EGLE may have significant astrophysical effects.

  13. Climate Resiliency Planning: Making Extreme Event Science Useful for Managers and Planners in Northern Nevada

    Science.gov (United States)

    McCarthy, M.; Kenneston, A.; Wall, T. U.; Brown, T. J.; Redmond, K. T.

    2014-12-01

    Effective climate resiliency planning at the regional level requires extensive interactive dialogue among climate scientists, emergency managers, public health officials, urban planners, social scientists, and policy makers. Engaging federal, tribal, state, local governments and private sector business and infrastructure owners/operators in defining, assessing and characterizing the impacts of extreme events allows communities to understand how different events "break the system" forcing local communities to seek support and resources from state/federal governments and/or the private sector and what actions can be taken proactively to mitigate consequences and accelerate recovery. The Washoe County Regional Resiliency Study was prepared in response to potential climate variability related impacts specific to the Northern Nevada Region. The last several decades have seen dramatic growth in the region, coupled with increased resource demands that have forced local governments to consider how those impacts will affect the region and may, in turn, impact the region's ability to provide essential services. The Western Regional Climate Center of the Desert Research Institute provided a synthesis of climate studies with predictions regarding plausible changes in the local climate of Northern California and Nevada for the next 50 years. In general, these predictions indicate that the region's climate is undergoing a gradual shift, which will primarily affect the frequency, amount, and form of precipitation in the Sierra Nevada and Great Basin. Changes in water availability and other extreme events may have serious and long lasting effects in the Northern Nevada Region, and create a variety of social, environmental and economic concerns. A range of extreme events were considered including Adverse Air Quality, Droughts, Floods, Heat Waves, High Wind, Structure Fires, Wildland Fires, and Major Winter Storms. Due to the complexity of our climate systems, and the difficulty in

  14. Cosmic rays Monte Carlo simulations for the Extreme Energy Events Project

    CERN Document Server

    Abbrescia, M; Aiola, S; Antolini, R; Avanzini, C; Baldini Ferroli, R; Bencivenni, G; Bossini, E; Bressan, E; Chiavassa, A; Cicalò, C; Cifarelli, L; Coccia, E; De Gruttola, D; De Pasquale, S; Di Giovanni, A; D'Incecco, M; Dreucci, M; Fabbri, F L; Frolov, V; Garbini, M; Gemme, G; Gnesi, I; Gustavino, C; Hatzifotiadou, D; La Rocca, P; Li, S; Librizzi, F; Maggiora, A; Massai, M; Miozzi, S; Panareo, M; Paoletti, R; Perasso, L; Pilo, F; Piragino, G; Regano, A; Riggi, F; Righini, G C; Sartorelli, G; Scapparone, E; Scribano, A; Selvi, M; Serci, S; Siddi, E; Spandre, G; Squarcia, S; Taiuti, M; Tosello, F; Votano, L; Williams, M C S; Yánez, G; Zichichi, A; Zuyeuski, R

    2014-01-01

    The Extreme Energy Events Project (EEE Project) is an innovative experiment to study very high energy cosmic rays by means of the detection of the associated air shower muon component. It consists of a network of tracking detectors installed inside Italian High Schools. Each tracking detector, called EEE telescope, is composed of three Multigap Resistive Plate Chambers (MRPCs). At present, 43 telescopes are installed and taking data, opening the way for the detection of far away coincidences over a total area of about 3 × 10 5 km 2 . In this paper we present the Monte Carlo simulations that have been performed to predict the expected coincidence rate between distant EEE telescopes.

  15. Extreme temperature events in Central Europe: are climate models able to reproduce them?

    Czech Academy of Sciences Publication Activity Database

    Kyselý, Jan; Huth, Radan

    Bratislava : Geophysical Institute of SAS, Slovak Hydrometeorological Institute, Slovak Mining Society, Slovak Meteorological Society, 2001 - (Matejka, F.; Ostrožlík, M.), s. - ISBN 80-85754-10-X. [150 years of the meteorological service in central Europe. Stará Lesná (SK), 09.10.2001-11.10.2001] R&D Projects: GA ČR GA205/99/1561; GA AV ČR IAA3042903 Institutional research plan: CEZ:AV0Z3042911 Keywords : extreme temperature events * long-term temperature series * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology

  16. Comparison of annual maximum series and partial duration series methods for modeling extreme hydrologic events

    DEFF Research Database (Denmark)

    Madsen, Henrik; Pearson, Charles P.; Rosbjerg, Dan

    1997-01-01

    Two regional estimation schemes, based on, respectively, partial duration series (PDS) and annual maximum series (AMS), are compared. The PDS model assumes a generalized Pareto (GP) distribution for modeling threshold exceedances corresponding to a generalized extreme value (GEV) distribution for...... annual maxima. First, the accuracy of PDS/GP and AMS/GEV regional index-flood T-year event estimators are compared using Monte Carlo simulations. For estimation in typical regions assuming a realistic degree of heterogeneity, the PDS/GP index-flood model is more efficient. The regional PDS and AMS...

  17. The impact of extreme flooding events and anthropogenic stressors on the macrobenthic communities’ dynamics

    Science.gov (United States)

    Cardoso, P. G.; Raffaelli, D.; Lillebø, A. I.; Verdelhos, T.; Pardal, M. A.

    2008-02-01

    Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Over period 1980-2000, the environment of the Mondego estuary, Portugal, has deteriorated through eutrophication, manifested in the replacement of seagrasses by opportunistic macroalgae, degradation of water quality and increased turbidity, and the system has also experienced extreme flood events. A restoration plan was implemented in 1998 which aimed to reverse the eutrophication effects, especially to restore the original natural seagrass ( Zostera noltii) community. This paper explores the interactions between extreme weather events (e.g. intense floods) and anthropogenic stressors (e.g. eutrophication) on the dynamics of the macrobenthic assemblages and the socio-economic implications that follow. We found that during the previous decade, the intensification of extreme flooding events had significant effects on the structure and functioning of macrobenthic communities, specifically a decline in total biomass, a decline in species richness and a decline in suspension feeders. However, the earlier eutrophication process also strongly modified the macrobenthic community, seen as a decline in species richness, increase in detritivores and a decline in herbivores together with a significant increase in small deposit-feeding polychaetes. After the implementation of the management plan, macrobenthic assemblages seemed to be recovering from eutrophication, but it is argued here that those earlier impacts reduced system stability and the resilience of the macrobenthic assemblages, so that its ability to cope with other stressors was compromised. Thus

  18. North American Extreme Temperature Events and Related Large Scale Meteorological Patterns: A Review of Statistical Methods, Dynamics, Modeling, and Trends

    Energy Technology Data Exchange (ETDEWEB)

    Grotjahn, Richard; Black, Robert; Leung, Lai-Yung R.; Wehner, Michael F.; Barlow, Mathew; Bosilovich, Michael; Gershunov, Alexander; Gutowski, William; Gyakum, John R.; Katz, Richard W.; Lee, Yun-Young; Lim, Young-Kwon; Prabhat,

    2016-02-01

    This paper reviews research approaches and open questions regarding data, statistical analyses, dynamics, modeling efforts, and trends in relation to temperature extremes. Our specific focus is upon extreme events of short duration (roughly less than 5 days) that affect parts of North America. These events are associated with large scale meteorological patterns (LSMPs). Methods used to define extreme events statistics and to identify and connect LSMPs to extreme temperatures are presented. Recent advances in statistical techniques can connect LSMPs to extreme temperatures through appropriately defined covariates that supplements more straightforward analyses. A wide array of LSMPs, ranging from synoptic to planetary scale phenomena, have been implicated as contributors to extreme temperature events. Current knowledge about the physical nature of these contributions and the dynamical mechanisms leading to the implicated LSMPs is incomplete. There is a pressing need for (a) systematic study of the physics of LSMPs life cycles and (b) comprehensive model assessment of LSMP-extreme temperature event linkages and LSMP behavior. Generally, climate models capture the observed heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreaks frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Climate models have been used to investigate past changes and project future trends in extreme temperatures. Overall, modeling studies have identified important mechanisms such as the effects of large-scale circulation anomalies and land-atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs more specifically to understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated so more

  19. Extreme events in the dispersions of two neighboring particles under the influence of fluid turbulence

    CERN Document Server

    Scatamacchia, R; Toschi, F

    2012-01-01

    We present a numerical study of two-particle dispersion from point-sources in 3D incompressible Homogeneous and Isotropic turbulence, at Reynolds number Re \\simeq 300. Tracer particles are emitted in bunches from localized sources smaller than the Kolmogorov scale. We report the first quantitative evidence, supported by an unprecedented statistics, of the deviations of relative dispersion from Richardson's picture. Deviations are due to extreme events of pairs separating much faster than average, and of pairs remaining close for long times. The two classes of events are the fingerprint of complete different physics, the former being dominated by inertial subrange and large-scale fluctuations, while the latter by the dissipation subrange. A comparison of relative separation in surrogate white-in-time velocity field, with correct viscous-, inertial- and integral-scale properties allows us to assess the importance of temporal correlations along tracer trajectories.

  20. Public health and climate change. The example of extreme weather events

    International Nuclear Information System (INIS)

    Climate change may be considered as a key factor for environmental change, exposure to health risks and pathogens, consequently impairing the state of health among populations. Health surveillance Systems can be used 1) to trigger early warning Systems, 2) to create databases which improve scientific knowledge about the health impacts of climate change, 3) to identify and prioritize needs for intervention and adaptation measures, and 4) to evaluate these measures. InVS proposed a method to identify possible health risks and to assess the needs for strengthened health surveillance Systems, taking into account environment, individual and social behaviors, demography and health state. Extreme climate events are illustrated here. These events have short, medium and long term impacts that could be reduced through efficient prevention. To better understand these impacts and orientate prevention, interdisciplinary studies will be needed. (authors)

  1. Temperature sensitivity of extreme precipitation events in the south-eastern Alpine forelands

    Science.gov (United States)

    Schroeer, Katharina; Kirchengast, Gottfried

    2016-04-01

    How will convective precipitation intensities and patterns evolve in a warming climate on a regional to local scale? Studies on the scaling of precipitation intensities with temperature are used to test observational and climate model data against the hypothesis that the change of precipitation with temperature will essentially follow the Clausius-Clapeyron (CC) equation, which corresponds to a rate of increase of the water holding capacity of the atmosphere by 6-7 % per Kelvin (CC rate). A growing number of studies in various regions and with varying approaches suggests that the overall picture of the temperature-precipitation relationship is heterogeneous, with scaling rates shearing off the CC rate in both upward and downward directions. In this study we investigate the temperature scaling of extreme precipitation events in the south-eastern Alpine forelands of Austria (SEA) based on a dense rain gauge net of 188 stations, with sub-daily precipitation measurements since about 1990 used at 10-min resolution. Parts of the study region are European hot-spots for severe hailstorms and the region, which is in part densely populated and intensively cultivated, is generally vulnerable to climate extremes. Evidence on historical extremely heavy short-time and localized precipitation events of several hundred mm of rain in just a few hours, resulting in destructive flash flooding, underline these vulnerabilities. Heavy precipitation is driven by Mediterranean moisture advection, enhanced by the orographic lifting at the Alpine foothills, and hence trends in positive sea surface temperature anomalies might carry significant risk of amplifying future extreme precipitation events. In addition, observations from the highly instrumented subregion of south-eastern Styria indicate a strong and robust long-term warming trend in summer of about 0.7°C per decade over 1971-2015, concomitant with a significant increase in the annual number of heat days. The combination of these

  2. Flood-risk mapping: contributions towards an enhanced assessment of extreme events and associated risks

    Directory of Open Access Journals (Sweden)

    B. Büchele

    2006-01-01

    Full Text Available Currently, a shift from classical flood protection as engineering task towards integrated flood risk management concepts can be observed. In this context, a more consequent consideration of extreme events which exceed the design event of flood protection structures and failure scenarios such as dike breaches have to be investigated. Therefore, this study aims to enhance existing methods for hazard and risk assessment for extreme events and is divided into three parts. In the first part, a regionalization approach for flood peak discharges was further developed and substantiated, especially regarding recurrence intervals of 200 to 10 000 years and a large number of small ungauged catchments. Model comparisons show that more confidence in such flood estimates for ungauged areas and very long recurrence intervals may be given as implied by statistical analysis alone. The hydraulic simulation in the second part is oriented towards hazard mapping and risk analyses covering the whole spectrum of relevant flood events. As the hydrodynamic simulation is directly coupled with a GIS, the results can be easily processed as local inundation depths for spatial risk analyses. For this, a new GIS-based software tool was developed, being presented in the third part, which enables estimations of the direct flood damage to single buildings or areas based on different established stage-damage functions. Furthermore, a new multifactorial approach for damage estimation is presented, aiming at the improvement of damage estimation on local scale by considering factors like building quality, contamination and precautionary measures. The methods and results from this study form the base for comprehensive risk analyses and flood management strategies.

  3. The Effects of Model Resolution on the Simulation of Regional Climate Extreme Events

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The fifth-generation Pennsylvania State University/NCAR Mesoscale Model Version 3 (MM5V3) was used to simulate extreme heavy rainfall events over the Yangtze River Basin in June 1999. The effects of model's horizontal and vertical resolution on the extreme climate events were investigated in detail. In principle, the model was able to characterize the spatial distribution of monthly heavy precipitation. The results indicated that the increase in horizontal resolution could reduce the bias of the modeled heavy rain and reasonably simulate the change of daily precipitation during the study period. A finer vertical resolution led to obviously improve rainfall simulations with smaller biases, and hence, better resolve heavy rainfall events. The increase in both horizontal and vertical resolution could produce better predictions of heavy rainfall events. Not only the rainfall simulation altered in the cases of different horizontal and vertical grid spacing, but also other meteorological fields demonstrated diverse variations in terms of resolution change in the model. An evident improvement in the simulated sea level pressure resulted from the increase of horizontal resolution, but the simulation was insensitive to vertical grid spacing. The increase in vertical resolution could enhance the simulation of surface temperature as well as atmospheric circulation at low levels, while the simulation of circulation at middle and upper levels were found to be much less dependent on changing resolution. In addition, cumulus parameterization schemes showed high sensitivity to horizontal resolution. Different convective schemes exhibited large discrepancies in rainfall simulations with regards to changing resolution. The percentage of convective precipitation in the Grell scheme increased with increasing horizontal resolution. In contrast, the Kain-Fritsch scheme caused a reduced ratio of convective precipitation to total rainfall accumulations corresponding to increasing

  4. Spatiotemporal distribution characteristics and attribution of extreme regional low temperature event

    Science.gov (United States)

    Feng, Tai-Chen; Zhang, Ke-Quan; Su, Hai-Jing; Wang, Xiao-Juan; Gong, Zhi-Qiang; Zhang, Wen-Yu

    2015-10-01

    Based on an objective identification technique for regional low temperature event (OITRLTE), the daily minimum temperature in China has been detected from 1960 to 2013. During this period, there were 60 regional extreme low temperature events (ERLTEs), which are included in the 690 regional low temperature events (RLTEs). The 60 ERLTEs are analyzed in this paper. The results show that in the last 50 years, the intensity of the ERLTEs has become weak; the number of lasted days has decreased; and, the affected area has become small. However, that situation has changed in this century. In terms of spatial distribution, the high intensity regions are mainly in Northern China while the high frequency regions concentrate in Central and Eastern China. According to the affected area of each event, the 60 ERLTEs are classified into six types. The atmospheric circulation background fields which correspond to these types are also analyzed. The results show that, influenced by stronger blocking highs of Ural and Lake Baikal, as well as stronger southward polar vortex and East Asia major trough at 500-hPa geopotential height, cold air from high latitudes is guided to move southward and abnormal northerly winds at 850 hPa makes the cold air blow into China along diverse paths, thereby forming different types of regional extreme low temperatures in winter. Project supported by the National Natural Science Foundation of China (Grant No. 41305075), the National Basic Research Program of China (Grant Nos. 2012CB955203 and 2012CB955902), and the Special Scientific Research on Public Welfare Industry, China (Grant No. GYHY201306049).

  5. Tropical vegetation and climate related to Dansgaard-Oeschger cycles and Heinrich events: high resolution palynological study of environmental change in northern South America during Marine Isotope Stage 3

    OpenAIRE

    Gonzalez Arango, Catalina

    2008-01-01

    High resolution paleoclimate records have revealed that during the last glacial period, the climate of the Earth was dominated by abrupt and widespread millennial-scale climatic changes, the so-called Dansgaard-Oeschger (D-O) oscillations and Heinrich events (HEs). Today, little is known about the role of the tropics in the transmission and amplification of D-O oscillations and HEs. This study is based on the palynological analysis of marine sediment core MD03-2622 from the Cariaco Basin, off...

  6. Climate projections of future extreme events accounting for modelling uncertainties and historical simulation biases

    Science.gov (United States)

    Brown, Simon J.; Murphy, James M.; Sexton, David M. H.; Harris, Glen R.

    2014-11-01

    A methodology is presented for providing projections of absolute future values of extreme weather events that takes into account key uncertainties in predicting future climate. This is achieved by characterising both observed and modelled extremes with a single form of non-stationary extreme value (EV) distribution that depends on global mean temperature and which includes terms that account for model bias. Such a distribution allows the prediction of future "observed" extremes for any period in the twenty-first century. Uncertainty in modelling future climate, arising from a wide range of atmospheric, oceanic, sulphur cycle and carbon cycle processes, is accounted for by using probabilistic distributions of future global temperature and EV parameters. These distributions are generated by Bayesian sampling of emulators with samples weighted by their likelihood with respect to a set of observational constraints. The emulators are trained on a large perturbed parameter ensemble of global simulations of the recent past, and the equilibrium response to doubled CO2. Emulated global EV parameters are converted to the relevant regional scale through downscaling relationships derived from a smaller perturbed parameter regional climate model ensemble. The simultaneous fitting of the EV model to regional model data and observations allows the characterisation of how observed extremes may change in the future irrespective of biases that may be present in the regional models simulation of the recent past climate. The clearest impact of a parameter perturbation in this ensemble was found to be the depth to which plants can access water. Members with shallow soils tend to be biased hot and dry in summer for the observational period. These biases also appear to have an impact on the potential future response for summer temperatures with some members with shallow soils having increases for extremes that reduce with extreme severity. We apply this methodology for London, using the

  7. Application of radar data to estimate distributed return periods of extreme rainfall events over Trondheim

    Energy Technology Data Exchange (ETDEWEB)

    Abdella, Yisak Sultan

    2013-07-01

    The return period of a given rainfall intensity is an important parameter for the Trondheim municipality since the drainage systems in Trondheim have been and are still being designed on the basis of a selected return period. Since rainfall is a spatially distributed phenomenon, a single event passing over a city can yield different return periods at different locations in the same city. In order to account for this spatial variability, a tool has been developed in this project for determining distributed return periods for rainfall events over Trondheim using the measurements from Rissa radar. The tool includes a method for adjusting radar rainfall using rain gauge measurements and an accumulation technique which accounts for storm movement and temporal variation in intensity. The tool has been tested on two extreme events which occurred on July 29 2007 and August 13 2007. The application on the two events has demonstrated a fully-automated estimation of distributed return periods using readily available data. For the particular rain gauge network in Trondheim, it has also been shown how areas of maximum intensity observed by the radar can be missed by all the gauges. (author)

  8. Impacts of the November 2014 extreme rainfall event in Ticino, Switzerland

    Science.gov (United States)

    Voumard, Jérémie; Matasci, Battista; Derron, Marc-Henri; Jaboyedoff, Michel

    2015-04-01

    the canton of Ticino with over 15'500 citizen, the shores along the Lake Maggiore were flooded until 300 meters inside the land. Dozens of basements and ground floor of buildings were flooded. Hillslopes were strongly affected by landslides, while floods occurred in valley bottoms. The aim of this study is to document the natural events and their consequences in terms of transportation networks and societal inconveniences caused by this rainfall event. Damages and consequences of the events were documented during a field visit, obtained from the media and the official reports as well as by the aid of a drone in two areas. We suspected that many impacted houses were located in areas where landslides could be expected. A first assessment based on geomorphological landscape analysis with an Airborne Lidar DEM show that some of these infrastructures seem to be built on alluvial / debris cones, suspected ancient landslides or steep slopes susceptible to be affected by (shallow) landslides, debris flows or rockfalls during extreme meteorological events. This raises the delicate question of urbanization in steep mountain slopes even if since a several tens of years nothing happened. More detailed studies about those hypotheses are necessary to understand the relationship between suspected old slope movements and the shallow landslides occurred during the November 2014 extreme rainfall event. The transportation network in the canton of Ticino is vulnerable to extreme natural events because of a high number of artificially cut and fill slopes along the lanes. In some cases, a possibility to investigate could be to reduce the number of roads leading to a same place in order to concentrate enough financial, logistic and maintenance strengths on only one access well protected against natural hazards.

  9. North American extreme temperature events and related large scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends

    Science.gov (United States)

    Grotjahn, Richard; Black, Robert; Leung, Ruby; Wehner, Michael F.; Barlow, Mathew; Bosilovich, Mike; Gershunov, Alexander; Gutowski, William J.; Gyakum, John R.; Katz, Richard W.; Lee, Yun-Young; Lim, Young-Kwon; Prabhat

    2016-02-01

    The objective of this paper is to review statistical methods, dynamics, modeling efforts, and trends related to temperature extremes, with a focus upon extreme events of short duration that affect parts of North America. These events are associated with large scale meteorological patterns (LSMPs). The statistics, dynamics, and modeling sections of this paper are written to be autonomous and so can be read separately. Methods to define extreme events statistics and to identify and connect LSMPs to extreme temperature events are presented. Recent advances in statistical techniques connect LSMPs to extreme temperatures through appropriately defined covariates that supplement more straightforward analyses. Various LSMPs, ranging from synoptic to planetary scale structures, are associated with extreme temperature events. Current knowledge about the synoptics and the dynamical mechanisms leading to the associated LSMPs is incomplete. Systematic studies of: the physics of LSMP life cycles, comprehensive model assessment of LSMP-extreme temperature event linkages, and LSMP properties are needed. Generally, climate models capture observed properties of heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreak frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Modeling studies have identified the impact of large-scale circulation anomalies and land-atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs to more specifically understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated. The paper concludes with unresolved issues and research questions.

  10. Complex Socio-Ecological Dynamics driven by extreme events in the Amazon

    Science.gov (United States)

    Pinho, P. F.

    2015-12-01

    Several years with extreme floods or droughts in the past decade have caused human suffering in remote communities of the Brazilian Amazon. Despite documented local knowledge and practices for coping with the high seasonal variability characteristic of the region's hydrology (e.g. 10m change in river levels between dry and flood seasons), and despite 'civil Defense' interventions by various levels of government, the more extreme years seem to have exceeded the coping capacity of the community. In this paper, we explore whether there is a real increase in variability, whether the community perceives that recent extreme events are outside the experience which shapes their responses to 'normal' levels of variability, and what science-based policy could contribute to greater local resilience. Hydrological analyses suggest that variability is indeed increasing, in line with expectations from future climate change. However, current measures of hydrological regimes do not predict years with social hardship very well. Interviewees in two regions are able to express their strategies for dealing with 'normal' variability very well, but also identify ways in which abnormal years exceed their ability to cope. Current Civil Defense arrangements struggle to deliver emergency assistance in a sufficiently timely and locally appropriate fashion. Combining these insights in the context of social-ecological change, we suggest how better integration of science, policy and local knowledge could improve resilience to future trends, and identify some contributions science could make into such an arrangement.

  11. Application of Data Cubes for Improving Detection of Water Cycle Extreme Events

    Science.gov (United States)

    Albayrak, Arif; Teng, William

    2015-01-01

    As part of an ongoing NASA-funded project to remove a longstanding barrier to accessing NASA data (i.e., accessing archived time-step array data as point-time series), for the hydrology and other point-time series-oriented communities, "data cubes" are created from which time series files (aka "data rods") are generated on-the-fly and made available as Web services from the Goddard Earth Sciences Data and Information Services Center (GES DISC). Data cubes are data as archived rearranged into spatio-temporal matrices, which allow for easy access to the data, both spatially and temporally. A data cube is a specific case of the general optimal strategy of reorganizing data to match the desired means of access. The gain from such reorganization is greater the larger the data set. As a use case of our project, we are leveraging existing software to explore the application of the data cubes concept to machine learning, for the purpose of detecting water cycle extreme events, a specific case of anomaly detection, requiring time series data. We investigate the use of support vector machines (SVM) for anomaly classification. We show an example of detection of water cycle extreme events, using data from the Tropical Rainfall Measuring Mission (TRMM).

  12. Prediction of a thermodynamic wave train from the monsoon to the Arctic following extreme rainfall events

    Science.gov (United States)

    Krishnamurti, T. N.; Kumar, Vinay

    2016-06-01

    This study addresses numerical prediction of atmospheric wave trains that provide a monsoonal link to the Arctic ice melt. The monsoonal link is one of several ways that heat is conveyed to the Arctic region. This study follows a detailed observational study on thermodynamic wave trains that are initiated by extreme rain events of the northern summer south Asian monsoon. These wave trains carry large values of heat content anomalies, heat transports and convergence of flux of heat. These features seem to be important candidates for the rapid melt scenario. This present study addresses numerical simulation of the extreme rains, over India and Pakistan, and the generation of thermodynamic wave trains, simulations of large heat content anomalies, heat transports along pathways and heat flux convergences, potential vorticity and the diabatic generation of potential vorticity. We compare model based simulation of many features such as precipitation, divergence and the divergent wind with those evaluated from the reanalysis fields. We have also examined the snow and ice cover data sets during and after these events. This modeling study supports our recent observational findings on the monsoonal link to the rapid Arctic ice melt of the Canadian Arctic. This numerical modeling suggests ways to interpret some recent episodes of rapid ice melts that may require a well-coordinated field experiment among atmosphere, ocean, ice and snow cover scientists. Such a well-coordinated study would sharpen our understanding of this one component of the ice melt, i.e. the monsoonal link, which appears to be fairly robust.

  13. Species interactions determine the spatial mortality patterns emerging in plant communities after extreme events.

    Science.gov (United States)

    Liao, Jinbao; Bogaert, Jan; Nijs, Ivan

    2015-01-01

    Gap disturbance is assumed to maintain species diversity by creating environmental heterogeneity. However, little is known about how interactions with neighbours, such as competition and facilitation, alter the emerging gap patterns after extreme events. Using a spatially explicit community model we demonstrate that negative interactions, especially intraspecific competition, greatly promote both average gap size and gap-size diversity relative to positive interspecific interaction. This suggests that competition would promote diversity maintenance but also increase community invasibility, as large gaps with a wide size variety provide more diverse niches for both local and exotic species. Under interspecific competition, both gap metrics interestingly increased with species richness, while they were reduced under intraspecific competition. Having a wider range of species interaction strengths led to a smaller average gap size only under intraspecific competition. Increasing conspecific clumping induced larger gaps with more variable sizes under intraspecific competition, in contrast to interspecific competition. Given the range of intraspecific clumping in real communities, models or experiments based on randomly synthesized communities may yield biased estimates of the opportunities for potential colonizers to fill gaps. Overall, our "static" model on gap formation offers perspectives to better predict recolonization opportunity and thus community secondary succession under extreme event regimes. PMID:26054061

  14. Responses of tree species to heat waves and extreme heat events.

    Science.gov (United States)

    Teskey, Robert; Wertin, Timothy; Bauweraerts, Ingvar; Ameye, Maarten; McGuire, Mary Anne; Steppe, Kathy

    2015-09-01

    The number and intensity of heat waves has increased, and this trend is likely to continue throughout the 21st century. Often, heat waves are accompanied by drought conditions. It is projected that the global land area experiencing heat waves will double by 2020, and quadruple by 2040. Extreme heat events can impact a wide variety of tree functions. At the leaf level, photosynthesis is reduced, photooxidative stress increases, leaves abscise and the growth rate of remaining leaves decreases. In some species, stomatal conductance increases at high temperatures, which may be a mechanism for leaf cooling. At the whole plant level, heat stress can decrease growth and shift biomass allocation. When drought stress accompanies heat waves, the negative effects of heat stress are exacerbated and can lead to tree mortality. However, some species exhibit remarkable tolerance to thermal stress. Responses include changes that minimize stress on photosynthesis and reductions in dark respiration. Although there have been few studies to date, there is evidence of within-species genetic variation in thermal tolerance, which could be important to exploit in production forestry systems. Understanding the mechanisms of differing tree responses to extreme temperature events may be critically important for understanding how tree species will be affected by climate change. PMID:25065257

  15. Preface: Monitoring and modelling to guide coastal adaptation to extreme storm events in a changing climate

    Science.gov (United States)

    Brown, J. M.; Ciavola, P.; Masselink, G.; McCall, R.; Plater, A. J.

    2016-02-01

    Storms across the globe and their associated consequences in coastal zones (flooding and erosion), combined with the long-term geomorphic evolution of our coastlines, are a threat to life and assets, both socioeconomic and environmental. In a changing climate, with a rising global sea level, potentially changing patterns in storm tracks and storminess, and rising population density and pressures on the coastal zone, the future risk of coastal storm impacts is likely to increase. Coastal managers and policy makers therefore need to make effective and timely decisions on the use of resources for the immediate and longer Research focused on "monitoring and modelling to guide coastal adaptation to extreme storm events in a changing climate" is becoming more common; its goal is to provide science-based decision support for effective adaptation to the consequences of storm impacts, both now and under future climate scenarios at the coast. The growing transfer of information between the science community and end-users is enabling leading research to have a greater impact on the socioeconomic resilience of coastal communities. This special issue covers recent research activities relating to coastal hazard mapping in response to extreme events, economic impacts of long-term change, coastal processes influencing management decisions and the development of online decision support tools.

  16. Extreme event return times in long-term memory processes near 1/f

    Directory of Open Access Journals (Sweden)

    F. Sienz

    2008-07-01

    Full Text Available The distribution of extreme event return times and their correlations are analyzed in observed and simulated long-term memory (LTM time series with 1/f power spectra. The analysis is based on tropical temperature and mixing ratio (specific humidity time series from TOGA COARE with 1 min resolution and an approximate 1/f power spectrum. Extreme events are determined by Peak-Over-Threshold (POT crossing. The Weibull distribution represents a reasonable fit to the return time distributions while the power-law predicted by the stretched exponential for 1/f deviates considerably. For a comparison and an analysis of the return time predictability, a very long simulated time series with an approximate 1/f spectrum is produced by a fractionally differenced (FD process. This simulated data confirms the Weibull distribution (a power law can be excluded. The return time sequences show distinctly weaker long-term correlations than the original time series (correlation exponent γ≈0.56.

  17. Integrated safety assessment of Indian nuclear power plants for extreme events: Reducing impact on public mind

    Indian Academy of Sciences (India)

    Anil Kakodkar; Ram Kumar Singh

    2013-10-01

    Nuclear energy professionals need to understand and address the catastrophe syndrome that of late seems to be increasingly at work in public mind in the context of nuclear energy. Classically the nuclear power reactor design and system evolution has been based on the logic of minimization of risk to an acceptable level and its quantification based on a deterministic approach and backed up by a further assessment based on the probabilistic methodology. However, in spite of minimization of risk, the reasons for anxiety and trauma in public mind that still prevails in the context of severe accidents needs to be understood and addressed. Margins between maximum credible accidents factored in the design and the ultimate load withstanding capacities of relevant systems need to be enhanced and guaranteed with a view to minimize release of radioactivity and avoid serious impact in public domain. A more realistic basis for management of an accident in public domain also needs to be quantified for this purpose. Assurance to public on limiting the consequences to a level that does not lead to a trauma is something that we need to be able to credibly demonstrate and confirm. The findings from Chernobyl reports point to significant psychological effects and related health disorders due to large scale emergency relocation of people that could have been possibly reduced by an order of magnitude without significant additional safety detriment. A combination of probabilistic and deterministic approaches should be evolved further to minimize consequences in public domain through enhancing safety margins and adding greater precision to quantitatively predicting accident progression and its management. The paper presents the case studies of the extreme external event such as tsunami and its impact on the coastal nuclear plants in India, the containment integrity assessment under the extreme internal event of over-pressurization and aircraft impact along with hydrogen deflagration

  18. Attribution of extreme events in the western US to human activities

    Science.gov (United States)

    Mera, R. J.

    2015-12-01

    A project to investigate the role of human activities on the changing nature of extreme events in the western US began as part of a CLIVAR-sponsored Postdocs Applying Climate Expertise (PACE) project. The climate institution was the Oregon State University and the application partner was the Oregon Department of Land Conservation and Development (DLCD). DLCD was interested in the changes in weather extremes in the Pacific Northwest, specifically extreme rainfall, flooding, and droughts. The project employs very large ensembles of regional model simulations through volunteer computing resources and allows for probabilistic event attribution (PEA), an important climate research technique. The model was found to have good representation of atmospheric rivers, a major source of extreme precipitation in the Pacific Northwest. The model domain also encompasses California and Nevada. One of the studies focused on attribution of extreme heat in relation to vulnerable populations in California's Central Valley, where heat waves have become progressively more severe due to increasing nighttime temperatures. Specifically, we found that that (1) simulations of the hottest summer days during the 2000s were twice as likely to occur using observed levels of greenhouse gases than in a counterfactual world without major human activities, (2) detrimental impacts of heat on public health-relevant variables, such as the number of days above 40°C, can be quantified and attributed to human activities using PEA, and (3) PEA can serve as a tool for addressing climate justice concerns of populations within developed nations. The research conducted through the PACE program has also provided a framework for a pioneering climate attribution study at the Union of Concerned Scientists (UCS). The UCS project takes advantage of new research that shows that nearly two-thirds of carbon pollution released into the atmosphere, reported as carbon dioxide equivalent with hundred-year global warming

  19. Total ozone patterns over the northern mid-latitudes: spatial correlations, extreme events and dynamical contributions

    Science.gov (United States)

    Rieder, H. E.; Staehelin, J.; Maeder, J. A.; Ribatet, M.; Bodeker, G. E.; Davison, A. C.

    2009-04-01

    Tools from geostatistics and extreme value theory are applied to analyze spatial correlations in total ozone for the northern mid-latitudes. The dataset used in this study is the NIWA combined total ozone dataset (Bodeker et al., 2001; Müller et al., 2008). New tools from extreme value theory (Coles, 2001; Ribatet, 2007) have recently been applied to the world's longest total ozone record from Arosa, Switzerland (e.g. Staehelin 1998a,b), in order to describe extreme events in low and high total ozone (Rieder et al., 200x). Within the current study, patterns in spatial correlation and frequency distributions of extreme events (e.g. ELOs and EHOs) are studied for the northern mid-latitudes. New insights in spatial patterns of total ozone for the northern mid-latitudes are presented. Koch et al. (2005) found that the increase in fast isentropic transport of tropical air to northern mid-latitudes contributed significantly to ozone changes between 1980 and 1989. Within this study the influence of changes in atmospheric dynamics (e.g. tropospheric and lower stratospheric pressure systems) on column ozone over the northern mid-latitudes is analyzed for the time period 1979-2007. References: Bodeker, G.E., J.C. Scott, K. Kreher, and R.L. McKenzie, Global ozone trends in potential vorticity coordinates using TOMS and GOME intercompared against the Dobson network: 1978-1998, J. Geophys. Res., 106 (D19), 23029-23042, 2001. Coles, S.: An Introduction to Statistical Modeling of Extreme Values, Springer Series in Statistics, ISBN:1852334592, Springer, Berlin, 2001. Koch, G., H. Wernli, C. Schwierz, J. Staehelin, and T. Peter (2005), A composite study on the structure and formation of ozone miniholes and minihighs over central Europe, Geophys. Res. Lett., 32, L12810, doi:10.1029/2004GL022062. Müller, R., Grooß, J.-U., Lemmen, C., Heinze, D., Dameris, M., and Bodeker, G.: Simple measures of ozone depletion in the polar stratosphere, Atmos. Chem. Phys., 8, 251-264, 2008. Ribatet

  20. The use of geoinformatic data and spatial analysis to predict faecal pollution during extreme precipitation events

    Science.gov (United States)

    Ward, Ray; Purnell, Sarah; Ebdon, James; Nnane, Daniel; Taylor, Huw

    2013-04-01

    The Water Framework Directive (WFD) regulates surface water quality standards in the European Union (EU). The Directive call for the identification and management of point and diffuse sources of pollution and requires the establishment of a 'programme of measures' for identified river basin districts, in order to achieve a "good status" by 2015. The hygienic quality of water is normally monitored using faecal indicator organisms (FIO), such as Escherichia coli, which indicate a potential risk to public health from human waterborne pathogens. Environmental factors influence the transmission of these pathogens and indicator organisms, and statistically significant relationships have been found between rainfall and outbreaks of waterborne disease. Climate change has been predicted to lead to an increase in severe weather events in many parts of Europe, including an increase in the frequency of extreme rainfall events. This in turn is likely to lead to an increase in incidents of human waterborne disease in Europe, unless measures are taken to predict and mitigate for such events. This study investigates a variety of environmental factors that influence the concentration of FIO in surface waters receiving faecal contamination from a variety of sources. Levels of FIO, including Escherichia coli, intestinal enterococci, somatic coliphage and GB124 (a human-specific microbial source tracking marker), were monitored in the Sussex Ouse catchment in Southeast England over a period of 26 months. These data were combined with geoinformatic environmental data within a GIS to map faecal contamination within the river. Previously, precipitation and soil erosion have been identified as major factors that can influence the concentration of these faecal markers, and studies have shown that slope, soil type and vegetation influence both the mechanisms and the rate by which erosion occurs in river catchments. Of the environmental variables studied, extreme precipitation was found to

  1. An Assessment of Direct and Indirect Economic Losses of Climatic Extreme Events

    Science.gov (United States)

    Otto, C.; Willner, S. N.; Wenz, L.; Levermann, A.

    2015-12-01

    Risk of extreme weather events like storms, heat extremes, and floods has already risen due to anthropogenic climate change and is likely to increase further under future global warming. Additionally, the structure of the global economy has changed importantly in the last decades. In the process of globalization, local economies have become more and more interwoven forming a complex network. Together with a trend towards lean production, this has resulted in a strong dependency of local manufacturers on global supply and value added chains, which may render the economic network more vulnerable to climatic extremes; outages of local manufacturers trigger indirect losses, which spread along supply chains and can even outstrip direct losses. Accordingly, in a comprehensive climate risk assessment these inter-linkages should be considered. Here, we present acclimate, an agent based dynamic damage propagation model. Its agents are production and consumption sites, which are interlinked by economic flows accounting for the complexity as well as the heterogeneity of the global supply network. Assessing the economic response on the timescale of the adverse event, the model permits to study temporal and spatial evolution of indirect production losses during the disaster and in the subsequent recovery phase of the economy. In this study, we focus on the dynamic economic resilience defined here as the ratio of direct to total losses. This implies that the resilience of the system under consideration is low if the high indirect losses are high. We find and assess a nonlinear dependence of the resilience on the disaster size. Further, we analyze the influence of the network structure upon resilience and discuss the potential of warehousing as an adaptation option.

  2. Statistical similarities of pre-earthquake electromagnetic emissions to biological and economic extreme events

    Science.gov (United States)

    Potirakis, Stelios M.; Contoyiannis, Yiannis; Kopanas, John; Kalimeris, Anastasios; Antonopoulos, George; Peratzakis, Athanasios; Eftaxias, Konstantinos; Nomicos, Costantinos

    2014-05-01

    When one considers a phenomenon that is "complex" refers to a system whose phenomenological laws that describe the global behavior of the system, are not necessarily directly related to the "microscopic" laws that regulate the evolution of its elementary parts. The field of study of complex systems considers that the dynamics of complex systems are founded on universal principles that may be used to describe disparate problems ranging from particle physics to economies of societies. Several authors have suggested that earthquake (EQ) dynamics can be analyzed within similar mathematical frameworks with economy dynamics, and neurodynamics. A central property of the EQ preparation process is the occurrence of coherent large-scale collective behavior with a very rich structure, resulting from repeated nonlinear interactions among the constituents of the system. As a result, nonextensive statistics is an appropriate, physically meaningful, tool for the study of EQ dynamics. Since the fracture induced electromagnetic (EM) precursors are observable manifestations of the underlying EQ preparation process, the analysis of a fracture induced EM precursor observed prior to the occurrence of a large EQ can also be conducted within the nonextensive statistics framework. Within the frame of the investigation for universal principles that may hold for different dynamical systems that are related to the genesis of extreme events, we present here statistical similarities of the pre-earthquake EM emissions related to an EQ, with the pre-ictal electrical brain activity related to an epileptic seizure, and with the pre-crisis economic observables related to the collapse of a share. It is demonstrated the all three dynamical systems' observables can be analyzed in the frame of nonextensive statistical mechanics, while the frequency-size relations of appropriately defined "events" that precede the extreme event related to each one of these different systems present striking quantitative

  3. Recent advances on reconstruction of climate and extreme events in China for the past 2000 year

    Science.gov (United States)

    Zheng, Jingyun; Hao, Zhixin; Ge, Quansheng; Liu, Yang

    2016-04-01

    The study of regional climate changes for past 2000 year could present spatial pattern of climate variation and various historical analogues for the sensitivity and operation of the climate system (e.g., the modulations of internal variability, feedbacks and teleconnections, abrupt changes and regional extreme events, etc.) from inter-annual to centennial scales and provide the knowledge to predict and project climate in the near future. China is distinguished by a prominent monsoon climate in east, continental arid climate in northwest and high land cold climate in Qinghai-Tibetan Plateau located at southwest. The long history of civilization and the variety of climate in China provides an abundant and well-dated documentary records and a wide range of natural archives (e.g., tree-ring, ice core, stalagmite, varved lake sediment, etc.) for high-resolution paleoclimate reconstruction. This paper presented a review of recent advances on reconstruction of climate and extreme events in China for the past 2000 years. In recent 10 years, there were many new high-resolution paleoclimatic reconstructions reported in China, e.g., the annual and decadal resolution series of temperature and precipitation in eastern China derived from historical documents, in western China derived from tree-ring and other natural archives. These new reconstructions provided more proxies and better spatial coverage to understand the characteristics of climate change over China and the uncertainty of regional reconstructions, as well as to reconstruct the high-resolution temperature series and the spatial pattern of precipitation change for whole China in the past millenniums by synthesizing the multi-proxy together. The updated results show that, in China, the warm intervals for the past 2000 years were in AD 1-200, AD 551-760, AD 951-1320, and after AD 1921; as well as the cold intervals were in AD 201-350, AD 441-530, AD 781-950, and AD 1321-1920. The extreme cold winters occurred in periods

  4. Tropopause folds in ERA-Interim: Global climatology and relation to extreme weather events

    Science.gov (United States)

    Škerlak, Bojan; Sprenger, Michael; Pfahl, Stephan; Tyrlis, Evangelos; Wernli, Heini

    2015-05-01

    Tropopause folds are intimately linked to upper level frontogenesis and jet stream dynamics. They play an important role for stratosphere-troposphere exchange, the dynamical coupling of upper and lower tropospheric levels, and for generating severe weather events. This study presents a global climatology of tropopause folds using ERA-Interim reanalysis data from 1979 to 2012 and a refined version of a previously developed 3-D labeling and fold identification algorithm. This algorithm objectively separates stratospheric and tropospheric air in complex situations, e.g., in regions with strong low-level inversions, and in extratropical cyclones where diabatically generated potential vorticity anomalies typically occur. Three classes of tropopause folds are defined (shallow, medium, and deep), and their geographical distribution, vertical extent, and seasonal cycle are investigated. Most shallow folds occur along the subtropical jet stream, in agreement with previous studies. Hot spots of medium and deep tropopause folds are found west of Australia and along the coast of Antarctica in the Southern Hemisphere and around the east coast of North America in the Northern Hemisphere. Seasonal cycles show maxima in winter for all fold classes. Medium and deep folds are frequently associated with surface wind gust and precipitation extremes, as quantified for folds over the southern Indian Ocean. Wind gust extremes occur mainly in an elongated band upstream and equatorward of folds, whereas precipitation extremes occur mainly east and poleward of folds. Overall, in the considered region, about 20% of medium folds and 33% of deep folds are associated with surface wind or precipitation extremes in the vicinity of the fold.

  5. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard

    DEFF Research Database (Denmark)

    Semenchuk, Philipp R.; Elberling, Bo; Cooper, Elisabeth J.

    2013-01-01

    years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme...... events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas...... frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5...

  6. Jellyfish: the origin and distribution of extreme ram-pressure stripping events in massive galaxy clusters

    Science.gov (United States)

    McPartland, Conor; Ebeling, Harald; Roediger, Elke; Blumenthal, Kelly

    2016-01-01

    We investigate the observational signatures and physical origin of ram-pressure stripping (RPS) in 63 massive galaxy clusters at z = 0.3-0.7, based on images obtained with the Hubble Space Telescope. Using a training set of a dozen `jellyfish' galaxies identified earlier in the same imaging data, we define morphological criteria to select 211 additional, less obvious cases of RPS. Spectroscopic follow-up observations of 124 candidates so far confirmed 53 as cluster members. For the brightest and most favourably aligned systems, we visually derive estimates of the projected direction of motion based on the orientation of apparent compression shocks and debris trails. Our findings suggest that the onset of these events occurs primarily at large distances from the cluster core (>400 kpc), and that the trajectories of the affected galaxies feature high-impact parameters. Simple models show that such trajectories are highly improbable for galaxy infall along filaments but common for infall at high velocities, even after observational biases are accounted for, provided the duration of the resulting RPS events is ≲500 Myr. We thus tentatively conclude that extreme RPS events are preferentially triggered by cluster mergers, an interpretation that is supported by the disturbed dynamical state of many of the host clusters. This hypothesis implies that extreme RPS might occur also near the cores of merging poor clusters or even merging groups of galaxies. Finally, we present nine additional `jellyfish" galaxies at z > 0.3 discovered by us, thereby doubling the number of such systems known at intermediate redshift.

  7. The effect of myostatin genotype on body temperature during extreme temperature events.

    Science.gov (United States)

    Howard, J T; Kachman, S D; Nielsen, M K; Mader, T L; Spangler, M L

    2013-07-01

    Extreme heat and cold events can create deleterious physiological changes in cattle as they attempt to cope. The genetic background of animals can influence their response to these events. The objective of the current study was to determine the impact of myostatin genotype (MG) on body temperature during periods of heat and cold stress. Two groups of crossbred steers and heifers of unknown pedigree and breed fraction with varying percentages of Angus, Simmental, and Piedmontese were placed in a feedlot over 2 summers and 2 winters. Before arrival, animals were genotyped for the Piedmontese-derived myostatin mutation (C313Y) to determine their MG as either homozygous normal (0 copy; n = 84), heterozygous (1 copy; n = 96), or homozygous for inactive myostatin (2 copy; n = 59). Hourly tympanic and vaginal temperature measurements were collected for steers and heifers, respectively, for 5 d during times of anticipated heat and cold stress. Mean (±SD) ambient temperature for summer and winter stress events were 24.4 (±4.64) and -1.80 (±11.71), respectively. A trigonometric function (sine + cosine) with periods of 12 and 24 h was used to describe the diurnal cyclical pattern. Hourly body temperature was analyzed within a season, and fixed effects included MG, group, trigonometric functions nested within group, and interaction of MG with trigonometric functions nested within group; random effects were animal and residual (Model [I]). A combined analysis of season and group was also investigated with the inclusion of season as a main effect and the nesting of effects within both group and season (Model [C]). In both models, the residual was fitted using an autoregressive covariance structure. A 3-way interaction of MG, season, and trigonometric function periodicities of 24 h (P 0.05). The current study illustrated that a genotype × environment interaction exists for MG and 1-copy animals were more robust to environmental extremes in comparison with 0- or 2-copy animals

  8. Assessment of extreme quantitative precipitation forecasts and development of regional extreme event thresholds using data from HMT-2006 and COOP observers

    Science.gov (United States)

    Ralph, F.M.; Sukovich, E.; Reynolds, D.; Dettinger, M.; Weagle, S.; Clark, W.; Neiman, P.J.

    2010-01-01

    Extreme precipitation events, and the quantitative precipitation forecasts (QPFs) associated with them, are examined. The study uses data from the Hydrometeorology Testbed (HMT), which conducted its first field study in California during the 2005/06 cool season. National Weather Service River Forecast Center (NWS RFC) gridded QPFs for 24-h periods at 24-h (day 1), 48-h (day 2), and 72-h (day 3) forecast lead times plus 24-h quantitative precipitation estimates (QPEs) fromsites in California (CA) and Oregon-Washington (OR-WA) are used. During the 172-day period studied, some sites received more than 254 cm (100 in.) of precipitation. The winter season produced many extreme precipitation events, including 90 instances when a site received more than 7.6 cm (3.0 in.) of precipitation in 24 h (i.e., an "event") and 17 events that exceeded 12.7 cm (24 h)-1 [5.0 in. (24 h)-1]. For the 90 extreme events f.7.6 cm (24 h)-1 [3.0 in. (24 h)-1]g, almost 90% of all the 270 QPFs (days 1-3) were biased low, increasingly so with greater lead time. Of the 17 observed events exceeding 12.7 cm (24 h)-1 [5.0 in. (24 h)-1], only 1 of those events was predicted to be that extreme. Almost all of the extreme events correlated with the presence of atmospheric river conditions. Total seasonal QPF biases for all events fi.e., $0.025 cm (24 h)-1 [0.01 in. (24 h)-1]g were sensitive to local geography and were generally biased low in the California-Nevada River Forecast Center (CNRFC) region and high in the Northwest River Forecast Center(NWRFC) domain. The low bias in CA QPFs improved with shorter forecast lead time and worsened for extreme events. Differences were also noted between the CNRFC and NWRFC in terms of QPF and the frequency of extreme events. A key finding from this study is that there were more precipitation events .7.6 cm (24 h)-1 [3.0 in. (24 h)21] in CA than in OR-WA. Examination of 422 Cooperative Observer Program (COOP) sites in the NWRFC domain and 400 in the CNRFC domain

  9. Extreme climatic event drives range contraction of a habitat-forming species

    Science.gov (United States)

    Smale, Dan A.; Wernberg, Thomas

    2013-01-01

    Species distributions have shifted in response to global warming in all major ecosystems on the Earth. Despite cogent evidence for these changes, the underlying mechanisms are poorly understood and currently imply gradual shifts. Yet there is an increasing appreciation of the role of discrete events in driving ecological change. We show how a marine heat wave (HW) eliminated a prominent habitat-forming seaweed, Scytothalia dorycarpa, at its warm distribution limit, causing a range contraction of approximately 100 km (approx. 5% of its global distribution). Seawater temperatures during the HW exceeded the seaweed's physiological threshold and caused extirpation of marginal populations, which are unlikely to recover owing to life-history traits and oceanographic processes. Scytothalia dorycarpa is an important canopy-forming seaweed in temperate Australia, and loss of the species at its range edge has caused structural changes at the community level and is likely to have ecosystem-level implications. We show that extreme warming events, which are increasing in magnitude and frequency, can force step-wise changes in species distributions in marine ecosystems. As such, return times of these events have major implications for projections of species distributions and ecosystem structure, which have typically been based on gradual warming trends. PMID:23325774

  10. Digital Learning Network Education Events of NASA's Extreme Environments Mission Operations

    Science.gov (United States)

    Paul, Heather; Guillory, Erika

    2007-01-01

    NASA's Digital Learning Network (DLN) reaches out to thousands of students each year through video conferencing and web casting. The DLN has created a series of live education videoconferences connecting NASA s Extreme Environment Missions Operations (NEEMO) team to students across the United States. The programs are also extended to students around the world live web casting. The primary focus of the events is the vision for space exploration. During the programs, NEEMO Crewmembers including NASA astronauts, engineers and scientists inform and inspire students about the importance of exploration and share the impact of the project as it correlates with plans to return to the moon and explore the planet Mars. These events highlight interactivity. Students talk live with the aquanauts in Aquarius, the National Oceanic and Atmospheric Administration s underwater laboratory. With this program, NASA continues the Agency s tradition of investing in the nation's education programs. It is directly tied to the Agency's major education goal of attracting and retaining students in science, technology, and engineering disciplines. Before connecting with the aquanauts, the students conduct experiments of their own designed to coincide with mission objectives. This paper describes the events that took place in September 2006.

  11. Inter-annual variability of carbon exchange and extreme events at the Loobos pine forest

    Science.gov (United States)

    Elbers, Jan; Moors, Eddy; Hutjes, Ronald; Jacobs, Cor; Jans, Wilma; Kruijt, Bart; Stolk, Petra; ter Maat, Herbert; Vermeulen, Marleen; Abreu, Pedro

    2013-04-01

    Introduction At the seasonal to inter-annual time scale large variations in net uptake exist as a result of changing weather conditions. It is therefore important to investigate the inter-annual variability of the uptake of forests as accurately as possible and relate it to physiological and physical constraints of the biosphere-atmosphere system. Present model concepts on NEE are well capable to reproduce average conditions, however they fail to reproduce short term variations. If we are able to explain these variations this will help to improve explaining inter-annual variability. We analysed the impact of extremes on inter-annual variation observed in measurements of eddy-covariance fluxes over the years 1997-2012 over a mid-latitude pine forest in The Netherlands. To improve our understanding of these variations, we tried to quantify and make a distinction between variations caused by environmental conditions by means of ecosystem response curves for real and maximum response. We analysed the remaining variation by looking at changes in site conditions, such as aging and nitrogen availability and disturbances caused by abrupt events such as storms, frost, harvest, fire etc. Results Based on annual totals, the inter-annual variability in NEE is the result of variations in Reco and, to a lesser extent, GPP. There is no evidence that annual meteorological averages are the main drivers for inter-annual variation in observed NEE. Response functions However at a monthly time step there is a strong correlation between GPP and radiation and to a lesser extend with temperature and maximum vapour pressure deficit. The correlation with VPDmax reflects the strong control VPD has on the stomatal closure of this eco-system. Reco correlates best with air temperature, marginally better than with superficial soil temperature. Including superficial soil moisture in the function slightly increases the correlation. Fitted response curves show that non-stressed ecosystem

  12. Quantifying the effect of trend, fluctuation, and extreme event of climate change on ecosystem productivity.

    Science.gov (United States)

    Liu, Yupeng; Yu, Deyong; Su, Yun; Hao, Ruifang

    2014-12-01

    Climate change comprises three fractions of trend, fluctuation, and extreme event. Assessing the effect of climate change on terrestrial ecosystem requires an understanding of the action mechanism of these fractions, respectively. This study examined 11 years of remotely sensed-derived net primary productivity (NPP) to identify the impacts of the trend and fluctuation of climate change as well as extremely low temperatures caused by a freezing disaster on ecosystem productivity in Hunan province, China. The partial least squares regression model was used to evaluate the contributions of temperature, precipitation, and photosynthetically active radiation (PAR) to NPP variation. A climatic signal decomposition and contribution assessment model was proposed to decompose climate factors into trend and fluctuation components. Then, we quantitatively evaluated the contributions of each component of climatic factors to NPP variation. The results indicated that the total contribution of the temperature, precipitation, and PAR to NPP variation from 2001 to 2011 in Hunan province is 85 %, and individual contributions of the temperature, precipitation, and PAR to NPP variation are 44 % (including 34 % trend contribution and 10 % fluctuation contribution), 5 % (including 4 % trend contribution and 1 % fluctuation contribution), and 36 % (including 30 % trend contribution and 6 % fluctuation contribution), respectively. The contributions of temperature fluctuation-driven NPP were higher in the north and lower in the south, and the contributions of precipitation trend-driven NPP and PAR fluctuation-driven NPP are higher in the west and lower in the east. As an instance of occasionally triggered disturbance in 2008, extremely low temperatures and a freezing disaster produced an abrupt decrease of NPP in forest and grass ecosystems. These results prove that the climatic trend change brought about great impacts on ecosystem productivity and that climatic fluctuations and

  13. Ecological implications of extreme events: footprints of the 2010 earthquake along the Chilean coast.

    Science.gov (United States)

    Jaramillo, Eduardo; Dugan, Jenifer E; Hubbard, David M; Melnick, Daniel; Manzano, Mario; Duarte, Cristian; Campos, Cesar; Sanchez, Roland

    2012-01-01

    Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chile's 2010 M(w) 8.8 earthquake along the entire rupture zone (ca. 34-38°S), we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky sub-tidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal ecosystems. PMID:22567101

  14. Ecological implications of extreme events: footprints of the 2010 earthquake along the Chilean coast.

    Directory of Open Access Journals (Sweden)

    Eduardo Jaramillo

    Full Text Available Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chile's 2010 M(w 8.8 earthquake along the entire rupture zone (ca. 34-38°S, we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky sub-tidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal

  15. Communicating Climate Uncertainties: Challenges and Opportunities Related to Spatial Scales, Extreme Events, and the Warming 'Hiatus'

    Science.gov (United States)

    Casola, J. H.; Huber, D.

    2013-12-01

    Many media, academic, government, and advocacy organizations have achieved sophistication in developing effective messages based on scientific information, and can quickly translate salient aspects of emerging climate research and evolving observations. However, there are several ways in which valid messages can be misconstrued by decision makers, leading them to inaccurate conclusions about the risks associated with climate impacts. Three cases will be discussed: 1) Issues of spatial scale in interpreting climate observations: Local climate observations may contradict summary statements about the effects of climate change on larger regional or global spatial scales. Effectively addressing these differences often requires communicators to understand local and regional climate drivers, and the distinction between a 'signal' associated with climate change and local climate 'noise.' Hydrological statistics in Missouri and California are shown to illustrate this case. 2) Issues of complexity related to extreme events: Climate change is typically invoked following a wide range of damaging meteorological events (e.g., heat waves, landfalling hurricanes, tornadoes), regardless of the strength of the relationship between anthropogenic climate change and the frequency or severity of that type of event. Examples are drawn from media coverage of several recent events, contrasting useful and potentially confusing word choices and frames. 3) Issues revolving around climate sensitivity: The so-called 'pause' or 'hiatus' in global warming has reverberated strongly through political and business discussions of climate change. Addressing the recent slowdown in warming yields an important opportunity to raise climate literacy in these communities. Attempts to use recent observations as a wedge between climate 'believers' and 'deniers' is likely to be counterproductive. Examples are drawn from Congressional testimony and media stories. All three cases illustrate ways that decision

  16. Water-borne diseases and extreme weather events in Cambodia: review of impacts and implications of climate change.

    Science.gov (United States)

    Davies, Grace I; McIver, Lachlan; Kim, Yoonhee; Hashizume, Masahiro; Iddings, Steven; Chan, Vibol

    2015-01-01

    Cambodia is prone to extreme weather events, especially floods, droughts and typhoons. Climate change is predicted to increase the frequency and intensity of such events. The Cambodian population is highly vulnerable to the impacts of these events due to poverty; malnutrition; agricultural dependence; settlements in flood-prone areas, and public health, governance and technological limitations. Yet little is known about the health impacts of extreme weather events in Cambodia. Given the extremely low adaptive capacity of the population, this is a crucial knowledge gap. A literature review of the health impacts of floods, droughts and typhoons in Cambodia was conducted, with regional and global information reviewed where Cambodia-specific literature was lacking. Water-borne diseases are of particular concern in Cambodia, in the face of extreme weather events and climate change, due to, inter alia, a high pre-existing burden of diseases such as diarrhoeal illness and a lack of improved sanitation infrastructure in rural areas. A time-series analysis under quasi-Poisson distribution was used to evaluate the association between floods and diarrhoeal disease incidence in Cambodian children between 2001 and 2012 in 16 Cambodian provinces. Floods were significantly associated with increased diarrhoeal disease in two provinces, while the analysis conducted suggested a possible protective effect from toilets and piped water. Addressing the specific, local pre-existing vulnerabilities is vital to promoting population health resilience and strengthening adaptive capacity to extreme weather events and climate change in Cambodia. PMID:25546280

  17. Water-Borne Diseases and Extreme Weather Events in Cambodia: Review of Impacts and Implications of Climate Change

    Directory of Open Access Journals (Sweden)

    Grace I. Davies

    2014-12-01

    Full Text Available Cambodia is prone to extreme weather events, especially floods, droughts and typhoons. Climate change is predicted to increase the frequency and intensity of such events. The Cambodian population is highly vulnerable to the impacts of these events due to poverty; malnutrition; agricultural dependence; settlements in flood-prone areas, and public health, governance and technological limitations. Yet little is known about the health impacts of extreme weather events in Cambodia. Given the extremely low adaptive capacity of the population, this is a crucial knowledge gap. A literature review of the health impacts of floods, droughts and typhoons in Cambodia was conducted, with regional and global information reviewed where Cambodia-specific literature was lacking. Water-borne diseases are of particular concern in Cambodia, in the face of extreme weather events and climate change, due to, inter alia, a high pre-existing burden of diseases such as diarrhoeal illness and a lack of improved sanitation infrastructure in rural areas. A time-series analysis under quasi-Poisson distribution was used to evaluate the association between floods and diarrhoeal disease incidence in Cambodian children between 2001 and 2012 in 16 Cambodian provinces. Floods were significantly associated with increased diarrhoeal disease in two provinces, while the analysis conducted suggested a possible protective effect from toilets and piped water. Addressing the specific, local pre-existing vulnerabilities is vital to promoting population health resilience and strengthening adaptive capacity to extreme weather events and climate change in Cambodia.

  18. Statistics of Extreme Gravitational Lensing Events; 2, the Small Shear Case

    CERN Document Server

    Wang, Y; Wang, Yun; Turner, Edwin L.

    1996-01-01

    We consider an astrophysical system with a population of sources and a population of lenses. For each pair of source and lens, there is a thin on-axis tube-like volume behind the lens in which the radiation flux from the source is greatly increased due to gravitational lensing. Any objects (such as dust grains) which pass through such a thin tube will experience strong bursts of radiation, i.e., Extreme Gravitational Lensing Events (EGLE). We study the physics and statistics of EGLE for the case in which the shear is larger or comparable to the finite source size. We find that the presence of shear has only a small effect on the EGLE statistics.

  19. EEE - Extreme Energy Events: an astroparticle physics experiment in Italian High Schools

    Science.gov (United States)

    Abbrescia, M.; Avanzini, C.; Baldini, L.; Baldini Ferroli, R.; Batignani, G.; Bencivenni, G.; Bossini, E.; Bressan, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; Corvaglia, A.; De Gruttola, D.; De Pasquale, S.; Di Giovanni, A.; D’Incecco, M.; Dreucci, M.; Fabbri, F. L.; Fattibene, E.; Ferrarov, A.; Forster, R.; Frolov, V.; Galeotti, P.; Garbini, M.; Gemme, G.; Gnesi, I.; Grazzi, S.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Maggiora, A.; Maron, G.; Mazziotta, M. N.; Miozzi, S.; Noferini, F.; Nozzoli, F.; Panareo, M.; Panetta, M. P.; Paoletti, R.; Perasso, L.; Pilo, F.; Piragino, G.; Riggi, F.; Righini, G. C.; Rodriguez Rodriguez, A.; Sartorelli, G.; Scapparone, E.; Schioppa, M.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Squarcia, S.; Taiuti, M.; Terreni, G.; Vistoli, M. C.; Votano, L.; Williams, M. C. S.; Zani, S.; Zichichi, A.; Zuyeuski, R.

    2016-05-01

    The Extreme Energy Events project (EEE) is aimed to study Extensive Air Showers (EAS) from primary cosmic rays of more than 1018 eV energy detecting the ground secondary muon component using an array of telescopes with high spatial and time resolution. The second goal of the EEE project is to involve High School teachers and students in this advanced research work and to initiate them in scientific culture: to reach both purposes the telescopes are located inside High School buildings and the detector construction, assembling and monitoring - together with data taking and analysis - are done by researchers from scientific institutions in close collaboration with them. At present there are 42 telescopes in just as many High Schools scattered all over Italy, islands included, plus two at CERN and three in INFN units. We report here some preliminary physics results from the first two common data taking periods together with the outreach impact of the project.

  20. Inelastic analysis and design of reinforced concrete structures submitted to induced vibrations of extreme events

    International Nuclear Information System (INIS)

    It is shown, that even with low plastification ratios a high reduction of strengthening measures is possible. This is verified by calculating elasto-plastic floor response design spectra for different plastification ratios on the basis of typical time histories due to induced vibrations of extreme events like aircraft or missile impact, explosion forces or pipe ruptures. The following will be recommended for the design of reinforced concrete structures and ductile equipment against the induced vibrations of short-time impact:-to make a simplified analysis with the peak accelerations of the floor time histories, without considering floor response spectra, - to calculate the elasto-plastic response only in those cases, where the additional strenghtening measures resulting from the above mentioned method are uneconomic. (Author)

  1. Real-time detection of an extreme scattering event: constraints on Galactic plasma lenses

    CERN Document Server

    Bannister, Keith W; Tuntsov, Artem V; Walker, Mark A; Johnston, Simon; Reynolds, Cormac; Bignall, Hayley

    2016-01-01

    Extreme scattering events (ESEs) are distinctive fluctuations in the brightness of astronomical radio sources caused by occulting plasma lenses in the interstellar medium. The inferred plasma pressures of the lenses are $\\sim 10^3$ times the ambient pressure, challenging our understanding of gas conditions in the Milky Way. Using a new survey technique, we have discovered an ESE while it was in progress. We report radio and optical follow-up observations. Modelling of the radio data demonstrates that the lensing structure is a density enhancement and that the lens is diverging, ruling out one of two competing physical models. Our technique will uncover many more ESEs, addressing a long-standing mystery of the small-scale gas structure of the Galaxy.

  2. Microbial utilization of litter carbon under the effect of extreme weather events

    Science.gov (United States)

    Heinrich, Steffen; Kuzyakov, Yakov; Glaser, Bruno

    2015-04-01

    Climate change is expected to not only lead to an increase of average annual temperature but also to increase the frequency of extreme meteorological events. For example, extreme summer-droughts followed by heavy rainfall events are likely to increase. This may change SOM quality, composition, microbial community functioning and thus C turnover in temperate forest ecosystems. Therefore, we performed a tracer experiment in the "Fichtelgebirge" (Northern Bavaria) to verify the influence of strong drying followed by intensive rewetting on the microbial community structure and decomposition of litter-derived 13C by individual microbial groups. In 2010, sheltered plots with artificially simulated drought, those with additional irrigation and control sites under natural conditions were established at a Norway spruce forest. At each plot, we added 13C enriched spruce litter to simulate annual litter fall. Thereafter, we assessed the effect of extreme weather events on microbial community structure by phospholipid fatty acid (PLFA) analysis. In addition, we analyzed the 13C incorporation into bulk soil, microbial biomass and PLFA of the organic horizon and the mineral soil up to 10 cm. Additionally respired CO2 was quantified by closed chambers. Drought reduced the microbial biomass only in the organic horizon, while in the mineral soil the microbial abundance did not decrease compared to the control and irrigated plots. The decrease in microbial biomass in the organic horizon of the drought plots resulted also in a strongly reduced incorporation of litter derived C: Incorporation of litter 13C was a magnitude of three lower in the drought plots compared to the control and irrigation plots. Furthermore, after the drought period of 90 days the proportion of 13C in CO2 from soil respiration was reduced by about 95% on the drought plots compared to the control and irrigated plots. This is in agreement with the reduced degradation of litter derived C and thus a reduced C

  3. Future extreme events in European climate: An exploration of regional climate model projections

    DEFF Research Database (Denmark)

    Beniston, M.; Stephenson, D.B.; Christensen, O.B.;

    2007-01-01

    regions of Holland, Germany and Denmark, in particular. These results are found to depend to different degrees on model formulation. While the responses of heat waves are robust to model formulation, the magnitudes of changes in precipitation and wind speed are sensitive to the choice of regional model......This paper presents an overview of changes in the extreme events that are most likely to affect Europe in forthcoming decades. A variety of diagnostic methods are used to determine how heat waves, heavy precipitation, drought, wind storms, and storm surges change between present (1961......-90) and future (2071-2 100) climate on the basis of regional climate model simulations produced by the PRUDENCE project. A summary of the main results follows. Heat waves - Regional surface warming causes the frequency, intensity and duration of heat waves to increase over Europe. By the end of the twenty first...

  4. Non-Gaussian statistics and spatially-organized extreme events on experimental fracture surfaces

    Science.gov (United States)

    Ponson, Laurent; Institut Jean le Rond d'Alembert Team

    2013-03-01

    The measurement of an abnormally high roughness exponent ζ ~= 0 . 80 on fracture surfaces of a large range of materials has been a long standing open question. Here, we revisit the roughness of cracks in metallic alloys and mortar where this value were reported, and show that this behavior is intimately connected with a non-Guaussian statistics of the height fluctuations of the fracture surfaces. The fat tails observed on the roughness distribution are shown to result from spatially organized domains where the local slope is abnormally large. This network of extreme events is characterized by long-range spatial correlations and power law statistics, and their scale of observations suggest that they are signature of microcracking in the material. Our findings support that damage is the central mechanism at the origin of the universal scaling behavior with ζ ~= 0 . 80 and open new perspectives in the quantitative investigation of microscopic failure processes from the analysis of fracture surfaces.

  5. Possible Impact of the Summer North Atlantic Oscillation on Extreme Hot Events in China

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Qi

    2012-01-01

    This paper reveals that the summer North Atlantic Oscillation (SNAO) is closely related to the extreme hot event (EHE) variability in China during the period of 1979 2009, with a positive-phase (negative-phase) SNAO corresponding to less (more) EHEs in northern China. The summer circulation anomalies associated with the SNAO give further confirmation of the above relationship. In a positive-phase (negative-phase) SNAO year, there is an anomalous cyclone (anticyclone) over central East Asia, which can increase (decrease) the total cloud cover over this region. Such changes of the total cloud cover can then decrease (increase) the solar radiation reaching the surface, which is consequently unfavorable (favorable) to the formation of EHEs over northern China.

  6. Uncertainties Related to Extreme Event Statistics of Sewer System Surcharge and Overflow

    DEFF Research Database (Denmark)

    Schaarup-Jensen, Kjeld; Johansen, C.; Thorndahl, Søren Liedtke

    Today it is common practice - in the major part of Europe - to base design of sewer systems in urban areas on recommended minimum values of flooding frequencies related to either pipe top level, basement level in buildings or level of road surfaces. Thus storm water runoff in sewer systems is only...... proceeding in an acceptable manner, if flooding of these levels is having an average return period bigger than a predefined value. This practice is also often used in functional analysis of existing sewer systems. If a sewer system can fulfil recommended flooding frequencies or not, can only be verified by...... corresponding extreme event statistics. This paper illustrates this problem in a case study with two different values of one input parameter - the hydrological reduction factor - in two otherwise identical operations of the MOUSE LTS model. The use of a long historical rainfall time series makes it possible to...

  7. Frequency analysis and its spatiotemporal characteristics of precipitation extreme events in China during 1951-2010

    Science.gov (United States)

    Shao, Yuehong; Wu, Junmei; Ye, Jinyin; Liu, Yonghe

    2015-08-01

    This study investigates frequency analysis and its spatiotemporal characteristics of precipitation extremes based on annual maximum of daily precipitation (AMP) data of 753 observation stations in China during the period 1951-2010. Several statistical methods including L-moments, Mann-Kendall test (MK test), Student's t test ( t test) and analysis of variance ( F-test) are used to study different statistical properties related to frequency and spatiotemporal characteristics of precipitation extremes. The results indicate that the AMP series of most sites have no linear trends at 90 % confidence level, but there is a distinctive decrease trend in Beijing-Tianjin-Tangshan region. The analysis of abrupt changes shows that there are no significant changes in most sites, and no distinctive regional patterns within the mutation sites either. An important innovation different from the previous studies is the shift in the mean and the variance which are also studied in this paper in order to further analyze the changes of strong and weak precipitation extreme events. The shift analysis shows that we should pay more attention to the drought in North China and to the flood control and drought in South China, especially to those regions that have no clear trend and have a significant shift in the variance. More important, this study conducts the comprehensive analysis of a complete set of quantile estimates and its spatiotemporal characteristic in China. Spatial distribution of quantile estimation based on the AMP series demonstrated that the values gradually increased from the Northwest to the Southeast with the increment of duration and return period, while the increasing rate of estimation is smooth in the arid and semiarid region and is rapid in humid region. Frequency estimates of 50-year return period are in agreement with the maximum observations of AMP series in the most stations, which can provide more quantitative and scientific basis for decision making.

  8. Tropopause Folds: Global Climatology and their Impact on Extreme Weather Events

    Science.gov (United States)

    Skerlak, B.; Sprenger, M.; Pfahl, S.; Wernli, H.

    2014-12-01

    Folded structures in the tropopause, so-called tropopause folds, are intimately linked to upper-level frontogenesis and jet-stream dynamics. They play an important role for stratosphere-troposphere exchange, the dynamical coupling of upper- and lower troposphere, and can be important for generating severe weather events. Together with the filamentation and roll-up of streamers and the formation of cut-off lows, tropopause folds are a prime example for the complex dynamical structure of the UTLS on time scales from hours to days. For case studies, in-situ data or detailed manual analysis of model output often allow for an unambiguous identification of the tropopause. Obtaining a global, long-term perspective of this phenomenon, however, requires an automated and objective identification method. We present an elaborated three-dimensional labelling algorithm, based on an isosurface of potential vorticity (PV), that allows to objectively separate stratospheric and tropospheric air in complex situations in polar regions and in situations with diabatically and/or frictionally generated PV anomalies typically found near extratropical cyclones. We apply this algorithm to the ERA-Interim reanalysis data set from 1979 to 2012 to compile a robust global climatology of tropopause folds. We present geographical and seasonal distributions of fold frequencies for three classes of folds as defined by their vertical extent (shallow, medium and deep). Typical synoptic situations associated with deep tropopause folds like cyclonically curved jets are discussed and we investigate their potential impact on extreme weather events. For example, the frequency of wind speed extremes at 700 hPa is in many areas significantly higher if a tropopause fold is present.

  9. Recent and future warm extreme events and high-mountain slope stability.

    Science.gov (United States)

    Huggel, C; Salzmann, N; Allen, S; Caplan-Auerbach, J; Fischer, L; Haeberli, W; Larsen, C; Schneider, D; Wessels, R

    2010-05-28

    The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future. Although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied, the impacts of short-term, unusually warm temperature increases on slope stability in high mountains remain largely unexplored. We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing. We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001-2050 compared with a 1951-2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5-4 times by 2050 and in some models by up to 10 times. Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw. Although these processes reduce slope strength, they must be considered within the local geological, glaciological and topographic context of a slope. PMID:20403836

  10. Prediction of the most extreme rainfall events in the South American Andes: A statistical forecast based on complex networks

    Science.gov (United States)

    Boers, Niklas; Bookhagen, Bodo; Barbosa, Henrique; Marwan, Norbert; Kurths, Jürgen; Marengo, Jose

    2015-04-01

    During the monsoon season, the subtropical Andes in South America are exposed to spatially extensive extreme rainfall events that frequently lead to flashfloods and landslides with severe socio-economic impacts. Since dynamical weather forecast has substantial problems with predicting the most extreme events (above the 99th percentile), alternative forecast methods are called for. Based on complex network theory, we developed a general mathematical framework for statistical prediction of extreme events in significantly interrelated time series. The key idea of our approach is to make the internal synchronization structure of extreme events mathematically accessible in terms of the topology of a network which is constructed from measuring the synchronization of extreme events at different locations. The application of our method to high-spatiotemporal resolution rainfall data (TRMM 3B42) reveals a migration pattern of large convective systems from southeastern South America towards the Argentinean and Bolivian Andes, against the direction of the northwesterly low-level moisture flow from the Amazon Basin. Once these systems reach the Andes, they lead to spatially extensive extreme events up to elevations above 4000m, leading to substantial risks of associated natural hazards. Based on atmospheric composites, we could identify an intricate interplay of frontal systems approaching from the South, low-level moisture flow from the Amazon Basin to the North, and the Andean orography as responsible climatic mechanism. These insights allow to formulate a simple forecast rule predicting 60% (90% during El Niño conditions) of extreme rainfall events at the eastern slopes of the subtropical Andes. The rule can be computed from readily available rainfall and pressure data and is already being tested by local institutions for disaster preparation.

  11. Evaluating Projected Changes in Mean Processes, Extreme Events, and their Spatio-Temporal Dependence Structures

    Science.gov (United States)

    Ganguly, A. R.; Steinhaeuser, K.; Kodra, E. A.; Kao, S.

    2010-12-01

    Observational datasets - both raw measurements and derived data products such as reanalysis data - are used to evaluate climate simulations run in forecast and hindcast modes. Bias and uncertainty in mean processes is quantified using statistical comparisons between observations and model-generated outputs. Weather and hydrological extremes under climate change are characterized using both event definitions and extreme value theory (EVT), and their aggregate statistics (intensity, duration and frequency) are likewise compared. The geographic variability and topographical biases are examined at continental to regional scales, and dependence structures (both spatio-temporal autocorrelation and long-range dependence) are assessed using statistical and nonlinear dynamical methods. These tools were developed primarily using the CMIP3/IPCC-AR4 archived model outputs, and are being additional tested with simulations from regional climate models which dynamically downscale the AR4 archives. This combination of traditional and novel tools is thus geared towards evaluation of multiple climate models which may handle processes or generate outputs at different spatial and temporal scales. The tools are expected to be immediately applicable to the CMIP5 data when it becomes available. The anticipated space-time resolutions will pose algorithmic challenges and computational demands, which will be addressed using analytic solutions and implementations thereof on high-performance scientific computing platforms.

  12. Boolean Delay Equations: A Simple Way of Looking at Interactions and Extreme Events

    Science.gov (United States)

    Ghil, Michael

    2013-04-01

    Boolean Delay Equations (BDEs) are semi-discrete dynamical models with Boolean-valued variables that evolve in continuous time. Systems of BDEs can be classified into conservative or dissipative, in a manner that parallels the classification of ordinary or partial differential equations. Solutions to certain conservative BDEs exhibit growth of complexity in time; such BDEs can be seen therefore as metaphors for biological evolution or human history. Dissipative BDEs are structurally stable and exhibit multiple equilibria and limit cycles, as well as more complex, fractal solution sets, such as Devil's staircases and ``fractal sunbursts.'' BDE systems have been used as highly idealized models of climate change on several time scales, as well as in earthquake modeling and prediction, and in genetics. BDEs with an infinite number of variables on a regular spatial grid have been called "partial BDEs" and we discuss connections with other types of discrete dynamical systems, including cellular automata and Boolean networks. We present recent BDE work on damage propagation in networks, with an emphasis on production-chain models. This formalism turns out to be well adapted to investigating propagation of an initial damage due to a climatic or other natural disaster. It thus serves to study economic impacts of extreme events, as well as extreme disruption of a network of interactions.

  13. Synergistic effects of an extreme weather event and habitat fragmentation on a specialised insect herbivore.

    Science.gov (United States)

    Piessens, Katrien; Adriaens, Dries; Jacquemyn, Hans; Honnay, Olivier

    2009-02-01

    Habitat fragmentation is considered to be one of the main causes of population decline and species extinction worldwide. Furthermore, habitat fragmentation can decrease the ability of populations to resist and to recover from environmental disturbances such as extreme weather events, which are expected to occur at an increasing rate as a result of climate change. In this study, we investigated how calcareous grassland fragmentation affected the impact of the climatically extreme summer of 2003 on egg deposition rates, population size variation and survival of the blue butterfly Cupido minimus, a specialist herbivore of Anthyllis vulneraria. Immediately after the 2003 summer heat wave, populations of the host plant declined in size; this was paralleled with decreases in population size of the herbivore and altered egg deposition rates. In 2006 at the end of the monitoring period, however, most A. vulneraria populations had recovered and only one population went extinct. In contrast, several butterfly populations had gone extinct between 2003 and 2006. Extinction probability was significantly related to initial population size, with small populations having a higher risk of extinction than large populations. These results support the prediction that species of higher trophic levels are more susceptible to extinction due to habitat fragmentation and severe disturbances. PMID:19002504

  14. Permafrost model sensitivity to seasonal climatic changes and extreme events in mountainous regions

    International Nuclear Information System (INIS)

    Climate models project considerable ranges and uncertainties in future climatic changes. To assess the potential impacts of climatic changes on mountain permafrost within these ranges of uncertainty, this study presents a sensitivity analysis using a permafrost process model combined with climate input based on delta-change approaches. Delta values comprise a multitude of coupled air temperature and precipitation changes to analyse long-term, seasonal and seasonal extreme changes on a typical low-ice content mountain permafrost location in the Swiss Alps. The results show that seasonal changes in autumn (SON) have the largest impact on the near-surface permafrost thermal regime in the model, and lowest impacts in winter (DJF). For most of the variability, snow cover duration and timing are the most important factors, whereas maximum snow height only plays a secondary role unless maximum snow heights are very small. At least for the low-ice content site of this study, extreme events have only short-term effects and have less impact on permafrost than long-term air temperature trends. (letter)

  15. Vulnerability and Risk Assessment of Extreme Weather Events- A Case Study from Bangladesh

    Science.gov (United States)

    Fakhruddin, S.; Mukand, M. S.; Kawasaki, A.; Webster, P. J.

    2013-12-01

    Assessment of hazard, vulnerability and risk of extreme weather are essential in order to inform and implement appropriate adaptation/prevention/mitigation strategies. Due to complex nature and uncertainties in future climate change predictions, it is not feasible to detail assessment of vulnerability at detailed scales for potential hazard and risk. Though different approaches and methods exist for running hazard, vulnerability and risk assessment, but still difficult to address all physical science, engineering, and social science research. In this study, we try to discuss on the human vulnerability and risk assessment approaches, tools and techniques of natural hazard due to extreme weather events (i.e. floods, cyclone). We analyzed different approaches and methods of vulnerability and risk assessment for flood hazard based on medium (1-10 days) and seasonal (1-3 months) ensembles probabilistic forecasts. The multiple weather ensembles (EPS) forecasts of European Center for Medium Range Forecasts (ECMWF) and downscaled Community Climate System Model Version 3 (CCSM3) forecasts data were used to set up hydrological model. Due to high uncertainty in forecasts information, results summarized that data and inherent low resolutions of the information are major constrains for details comprehensive assessment. Risk and vulnerability rises to be based on multi-scale and cross-scale analyses, considering resilience dimensions and provide innovative tools for understanding, assessing and communicating probabilistic information to the users for decision making. The sectoral responses were developed with possible impacts scenarios based on uncertainty ranges to choose the most robust solution.

  16. Dam safety and water management during unusual and extreme hydrologic events

    International Nuclear Information System (INIS)

    The Southwestern Division of the Army Corps of Engineers takes in all or part of Arkansas, Kansas, Missouri, Oklahoma, and Texas. Climate can be highly variable and unpredictable in this region of the country. In recent years a particularly wide range of hydrologic events has been ongoing. Most of the region was in a very severe drought from early 2004 through late 2006, resulting in many of the multipurpose flood control lakes being drawn down to near record low pools. This climactic trend then reversed, and by the summer of 2007 extreme flooding was occurring over a large portion of Texas, Oklahoma, and Kansas. In March and April 2008, record flooding was occurring in Arkansas. The White River system of multipurpose lakes was hit especially hard with record pools set at four of the five lakes. The challenges of excessive rainfall immediately following a prolonged period of drought can test whether existing water management plans are adequate to handle broad ranges of climactic conditions. This paper will explore the water management challenges faced by the 2008 flooding, how hydropower releases were used to increase total outflow to prevent overtopping and how existing water control plans effectively served to manage the extreme conditions while maintaining public safety and minimizing downstream losses. (author)

  17. Understanding and predicting the impact of extreme storms events on European coastlines: the MICORE approach

    Science.gov (United States)

    Ciavola, P.

    2009-04-01

    Both the EU and The United Nations are now taking seriously the predicted climate change scenarios of the IPCC. Of particular relevance to Integrated Coastal Zone Management is the predicted increase in the intensity and frequency of powerful storm events characterised by larger peak wind speeds and consequently larger waves. Engineering has usually been favoured in the past as the best option for disaster mitigation at the coast. However, most engineering works are constrained by economics, and a compromise is sought between the potential threat to lives and property and the resources available for design and construction. Furthermore, the design of structures is based on predicted extreme events which themselves are subject to uncertainty, especially in a rapidly changing global climate. The huge damage to the city of New Orleans by Hurricane Katrina illustrates clearly what can go wrong when the engineering design is subjected to forcing beyond its design limits and when civil evacuation and management plans fail. The proposed paper will address the issue of encouraging and facilitating exchange of information on storm impacts produced by nationally funded projects in Member States; establishing robust data management and data quality control and engaging with stakeholders and end users to optimise dissemination strategies. It will heavily rely on the information produced by the MICORE Project (FP7 contract 202798), using and enlarging the database collated by the project regarding the characteristics of extreme storm events occurred in the last 50 years. The MICORE project (www.micore.eu) will provide the knowledge necessary to assess the present day risks and to study the economic and social impact of future severe storm events. Together, these elements will have an important strategic impact on the safety of the people living in coastal areas and upon decision processes aimed at minimising the economic consequences of extreme events. The project will also

  18. A hypothesis on nanodust as a source of energy for extreme weather events and climate changes

    Science.gov (United States)

    Berkovich, Simon

    2013-03-01

    There are many phenomena that attract energy, the source of which cannot be unerringly identified. Among those are: excess heat alleged to nuclear processes, sonoluminescence, wire fragmentation under high voltage pulses, diverse biophysical experiences, and some atmospheric effects, like ball lightning and terrestrial gamma rays. Destructive atmospheric events associated with intense air movements, such as hurricanes and tornadoes, expend huge amounts of energy equivalent to very many nuclear bombs. Our paper indicates a possibility for a new source of energy due to the so-called ``hot-clocking'' effect related to the holographic mechanism of the Universe that establishes the exclusive property of nonlocality. This may uncover energy in various unusual appearances, particularly, in the suspected trend of global warming as a direct contribution to the extreme weather events. The surmised clocking impacts from holographic reference beam can reveal themselves through gaseous aerosols and suspended contaminants that may have been increased with human technogenesis. According to recent EPRI report nanopowder for Ni-Pd alloys in the size range of 5-10 nm was found to cause small amounts of excess power, about 4 watt per gram. So, using a minimal norm of contamination (20 micrograms per cubic meter) as an approximate guide, we could estimate that the whole atmosphere would thus generate dozens of terawatts, a contribution comparable to that of the Sun.

  19. Impacts of different climate change regimes and extreme climatic events on an alpine meadow community

    Science.gov (United States)

    Alatalo, Juha M.; Jägerbrand, Annika K.; Molau, Ulf

    2016-02-01

    Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversity

  20. Similarities between extreme events in the solar-terrestrial system by means of nonextensivity

    Directory of Open Access Journals (Sweden)

    G. Balasis

    2011-09-01

    Full Text Available The dynamics of complex systems are founded on universal principles that can be used to describe disparate problems ranging from particle physics to economies of societies. A corollary is that transferring ideas and results from investigators in hitherto disparate areas will cross-fertilize and lead to important new results. In this contribution, we investigate the existence of a universal behavior, if any, in solar flares, magnetic storms, earthquakes and pre-seismic electromagnetic (EM emissions, extending the work recently published by Balasis et al. (2011a. A common characteristic in the dynamics of the above-mentioned phenomena is that their energy release is basically fragmentary, i.e. the associated events are being composed of elementary building blocks. By analogy with earthquakes, the magnitude of the magnetic storms, solar flares and pre-seismic EM emissions can be appropriately defined. Then the key question we can ask in the frame of complexity is whether the magnitude distribution of earthquakes, magnetic storms, solar flares and pre-fracture EM emissions obeys the same law. We show that these apparently different extreme events, which occur in the solar-terrestrial system, follow the same energy distribution function. The latter was originally derived for earthquake dynamics in the framework of nonextensive Tsallis statistics.

  1. Going to the Extremes. An Intercomparison of Model-Simulated Historical and Future Changes in Extreme Events

    Energy Technology Data Exchange (ETDEWEB)

    Tebaldi, C. [Institute for the Study of Society and Environment, National Center for Atmospheric Research NCAR, PO BOX 3000, Boulder, CO 80301 (United States); Hayhoe, K. [Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Arblaster, J.M. [Bureau of Meteorology Research Centre, Melbourne (Australia); Meehl, G.A. [Climate and Global Dynamics Division, NCAR, Boulder, CO (United States)

    2006-12-15

    Projections of changes in climate extremes are critical to assessing the potential impacts of climate change on human and natural systems. Modeling advances now provide the opportunity of utilizing global general circulation models (GCMs) for projections of extreme temperature and precipitation indicators. We analyze historical and future simulations of ten such indicators as derived from an ensemble of 9 GCMs contributing to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4), under a range of emissions scenarios. Our focus is on the consensus from the GCM ensemble, in terms of direction and significance of the changes, at the global average and geographical scale. The climate extremes described by the ten indices range from heat-wave frequency to frost-day occurrence, from dry-spell length to heavy rainfall amounts. Historical trends generally agree with previous observational studies, providing a basic sense of reliability for the GCM simulations. Individual model projections for the 21st century across the three scenarios examined are in agreement in showing greater temperature extremes consistent with a warmer climate. For any specific temperature index, minor differences appear in the spatial distribution of the changes across models and across scenarios, while substantial differences appear in the relative magnitude of the trends under different emissions rates. Depictions of a wetter world and greater precipitation intensity emerge unequivocally in the global averages of most of the precipitation indices. However, consensus and significance are less strong when regional patterns are considered. This analysis provides a first overview of projected changes in climate extremes from the IPCC-AR4 model ensemble, and has significant implications with regard to climate projections for impact assessments.

  2. Going to the extremes. An intercomparison of model-simulated historical and future changes in extreme events (Erratum)

    Energy Technology Data Exchange (ETDEWEB)

    Tebaldi, C. [Institute for the Study of Society and Environment, National Center for Atmospheric Research NCAR, PO BOX 3000, Boulder, CO 80301 (United States); Hayhoe, K. [Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Arblaster, J.M. [Bureau of Meteorology Research Centre, Melbourne (Australia); Meehl, G.A. [Climate and Global Dynamics Division, NCAR, Boulder, CO (United States)

    2007-05-15

    This article is an erratum. The online version of the original article can be found at: doi:10.1007/s10584-006-9051-4. The abstract of that article was as follows: Projections of changes in climate extremes are critical to assessing the potential impacts of climate change on human and natural systems. Modeling advances now provide the opportunity of utilizing global general circulation models (GCMs) for projections of extreme temperature and precipitation indicators. We analyze historical and future simulations of ten such indicators as derived from an ensemble of 9 GCMs contributing to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4), under a range of emissions scenarios. Our focus is on the consensus from the GCM ensemble, in terms of direction and significance of the changes, at the global average and geographical scale. The climate extremes described by the ten indices range from heat-wave frequency to frost-day occurrence, from dry-spell length to heavy rainfall amounts. Historical trends generally agree with previous observational studies, providing a basic sense of reliability for the GCM simulations. Individual model projections for the 21st century across the three scenarios examined are in agreement in showing greater temperature extremes consistent with a warmer climate. For any specific temperature index, minor differences appear in the spatial distribution of the changes across models and across scenarios, while substantial differences appear in the relative magnitude of the trends under different emissions rates. Depictions of a wetter world and greater precipitation intensity emerge unequivocally in the global averages of most of the precipitation indices. However, consensus and significance are less strong when regional patterns are considered. This analysis provides a first overview of projected changes in climate extremes from the IPCC-AR4 model ensemble, and has significant implications with regard to

  3. Communicating natural hazards. The case of marine extreme events and the importance of the forecast's errors.

    Science.gov (United States)

    Marone, Eduardo; Camargo, Ricardo

    2013-04-01

    Scientific knowledge has to fulfill some necessary conditions. Among them, it has to be properly communicated. Usually, scientists (mis)understand that the communication requirement is satisfied by publishing their results on peer reviewed journals. Society claims for information in other formats or languages and other tools and approaches have to be used, otherwise the scientific discoveries will not fulfill its social mean. However, scientists are not so well trained to do so. These facts are particularly relevant when the scientific work has to deal with natural hazards, which do not affect just a lab or a computer experiment, but the life and fate of human beings. We are actually working with marine extreme events related with sea level changes, waves and other coastal hazards. Primary, the work is developed on the classic scientific format, but focusing not only in the stochastic way of predicting such extreme events, but estimating the potential errors the forecasting methodologies intrinsically have. The scientific results are translated to a friendly format required by stakeholders (which are financing part of the work). Finally, we hope to produce a document prepared for the general public. Each of the targets has their own characteristics and we have to use the proper communication tools and languages. Also, when communicating such knowledge, we have to consider that stakeholders and general public have no obligation of understanding the scientific language, but scientists have the responsibility of translating their discoveries and predictions in a proper way. The information on coastal hazards is analyzed in statistical and numerical ways, departing from long term observation of, for instance, sea level. From the analysis it is possible to recognize different natural regimes and to present the return times of extreme events, while from the numerical models, properly tuned to reproduce the same past ocean behavior using hindcast approaches, it is

  4. Long-term changes in the frequency, intensity and duration of extreme storm surge events in southern Europe

    Science.gov (United States)

    Cid, Alba; Menéndez, Melisa; Castanedo, Sonia; Abascal, Ana J.; Méndez, Fernando J.; Medina, Raúl

    2016-03-01

    Storm surges are one of the major hazards in coastal regions; positive surge events are added to tidal levels, increasing the risk of coastal flooding by extreme water levels. In this study, changes in the frequency (occurrence rate per year), intensity (magnitude of the extremes) and duration of extreme storm surge events from 1948 to 2013 are investigated using a non-stationary statistical model. To fully model extremes, the time-dependent statistical model combines the Generalized Pareto Distribution (GPD) for studying exceedances over the threshold, and the non-homogeneous Poisson (P) process for studying the occurrence rate of these exceedances. Long-term trends and the association between storm surges and the North Atlantic Oscillation (NAO) are represented in the model by allowing the parameters in the GPD-P model to be time-dependent. Different spatial patterns in the three analysed properties of storm surges are found in the Atlantic region and the Mediterranean Sea. The up to now uncharted regional patterns of storm surge duration show completely different values between the Atlantic and the Mediterranean regions, being the duration of storms surges in the Atlantic two times longer than the duration in the Mediterranean. For the last half century, we detect positive and negative spatial trends in terms of intensity of storm surge but only significant decreasing rates, of around 2 %, in the number of extreme events per year. Regarding duration, we find positive trends in certain Mediterranean areas, with durations of extreme events increasing at a rate of 0.5-1.5 h/year. Values for the 50-year return level are also estimated, showing a large spatial variability with relatively higher values along the coast. A clear sensitivity of extreme storm surges to negative NAO index is detected, specifically in the western Mediterranean basin. Results show that negative NAO phases lead to an increase in the number of extreme events and also in their intensity.

  5. Climate-Related Hazards: A Method for Global Assessment of Urban and Rural Population Exposure to Cyclones, Droughts, and Floods

    Science.gov (United States)

    Christenson, Elizabeth; Elliott, Mark; Banerjee, Ovik; Hamrick, Laura; Bartram, Jamie

    2014-01-01

    Global climate change (GCC) has led to increased focus on the occurrence of, and preparation for, climate-related extremes and hazards. Population exposure, the relative likelihood that a person in a given location was exposed to a given hazard event(s) in a given period of time, was the outcome for this analysis. Our objectives were to develop a method for estimating the population exposure at the country level to the climate-related hazards cyclone, drought, and flood; develop a method that readily allows the addition of better datasets to an automated model; differentiate population exposure of urban and rural populations; and calculate and present the results of exposure scores and ranking of countries based on the country-wide, urban, and rural population exposures to cyclone, drought, and flood. Gridded global datasets on cyclone, drought and flood occurrence as well as population density were combined and analysis was carried out using ArcGIS. Results presented include global maps of ranked country-level population exposure to cyclone, drought, flood and multiple hazards. Analyses by geography and human development index (HDI) are also included. The results and analyses of this exposure assessment have implications for country-level adaptation. It can also be used to help prioritize aid decisions and allocation of adaptation resources between countries and within a country. This model is designed to allow flexibility in applying cyclone, drought and flood exposure to a range of outcomes and adaptation measures. PMID:24566046

  6. Climate-related hazards: a method for global assessment of urban and rural population exposure to cyclones, droughts, and floods.

    Science.gov (United States)

    Christenson, Elizabeth; Elliott, Mark; Banerjee, Ovik; Hamrick, Laura; Bartram, Jamie

    2014-02-01

    Global climate change (GCC) has led to increased focus on the occurrence of, and preparation for, climate-related extremes and hazards. Population exposure, the relative likelihood that a person in a given location was exposed to a given hazard event(s) in a given period of time, was the outcome for this analysis. Our objectives were to develop a method for estimating the population exposure at the country level to the climate-related hazards cyclone, drought, and flood; develop a method that readily allows the addition of better datasets to an automated model; differentiate population exposure of urban and rural populations; and calculate and present the results of exposure scores and ranking of countries based on the country-wide, urban, and rural population exposures to cyclone, drought, and flood. Gridded global datasets on cyclone, drought and flood occurrence as well as population density were combined and analysis was carried out using ArcGIS. Results presented include global maps of ranked country-level population exposure to cyclone, drought, flood and multiple hazards. Analyses by geography and human development index (HDI) are also included. The results and analyses of this exposure assessment have implications for country-level adaptation. It can also be used to help prioritize aid decisions and allocation of adaptation resources between countries and within a country. This model is designed to allow flexibility in applying cyclone, drought and flood exposure to a range of outcomes and adaptation measures. PMID:24566046

  7. Climate Products and Services to Meet the Challenges of Extreme Events

    Science.gov (United States)

    McCalla, M. R.

    2008-12-01

    The 2002 Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM1)-sponsored report, Weather Information for Surface Transportation: National Needs Assessment Report, addressed meteorological needs for six core modes of surface transportation: roadway, railway, transit, marine transportation/operations, pipeline, and airport ground operations. The report's goal was to articulate the weather information needs and attendant surface transportation weather products and services for those entities that use, operate, and manage America's surface transportation infrastructure. The report documented weather thresholds and associated impacts which are critical for decision-making in surface transportation. More recently, the 2008 Climate Change Science Program's (CCSP) Synthesis and Assessment Product (SAP) 4.7 entitled, Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study, Phase I, included many of the impacts from the OFCM- sponsored report in Table 1.1 of this SAP.2 The Intergovernmental Panel on Climate Change (IPCC) reported that since 1950, there has been an increase in the number of heat waves, heavy precipitation events, and areas of drought. Moreover, the IPCC indicated that greater wind speeds could accompany more severe tropical cyclones.3 Taken together, the OFCM, CCSP, and IPCC reports indicate not only the significance of extreme events, but also the potential increasing significance of many of the weather thresholds and associated impacts which are critical for decision-making in surface transportation. Accordingly, there is a real and urgent need to understand what climate products and services are available now to address the weather thresholds within the surface transportation arena. It is equally urgent to understand what new climate products and services are needed to address these weather thresholds, and articulate what can be done to fill the gap between the

  8. Jellyfish: Observational Properties of Extreme Ram-Pressure Stripping Events in Massive Galaxy Clusters

    Science.gov (United States)

    Conor, McPartland; Ebeling, Harald; Roediger, Elke

    2015-08-01

    We investigate the physical origin and observational signatures of extreme ram-pressure stripping (RPS) in 63 massive galaxy clusters at z=0.3-0.7, based on data in the F606W passband obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. Using a training set of a dozen ``jellyfish" galaxies identified earlier in the same imaging data, we define quantitative morphological criteria to select candidate galaxies which are similar to known cases of RPS. Considering a sample of 16 ``jellyfish" galaxies (10 of which we present for the first time), we visually derive estimates of the projected direction of motion based on dynamical features such as apparent compression shocks and debris trails. Our findings suggest that the observed events occur primarily at large distances from the cluster core and involve infall trajectories featuring high impact parameters. Simple models of cluster growth show that such trajectories are consistent with two scenarios: 1) galaxy infall along filaments; and 2) infall at high velocities (≥1000 km/s) characteristic of cluster mergers. The observed distribution of events is best described by timescales of ˜few Myr in agreement with recent numerical simulations of RPS. The broader areal coverage of the Hubble Frontier Fields should provide an even larger sample of RPS events to determine the relative contributions of infall and cluster mergers. Prompted by the discovery of several jellyfish galaxies whose brightness in the F606W passband rivals or exceeds that of the respective brightest cluster galaxy, we attempt to constrain the luminosity function of galaxies undergoing RPS. The observed significant excess at the bright end compared to the luminosity functions of blue cluster members strongly suggests enhanced star formation, thus challenging theoretical and numerical studies according to which RPS merely displaces existing star-forming regions. In-depth studies of individual objects will help test our

  9. Large geomagnetic storms of extreme solar event periods in solar cycle 23

    Science.gov (United States)

    Wang, Ruiguang

    During extreme solar events such as big flares or/and energetic coronal mass ejections (CMEs) high energy particles are accelerated by the shocks formed in front of fast interplanetary coronal mass ejections (ICMEs). The ICMEs (and their sheaths) also give rise to large geomagnetic storms which have significant effects on the Earth's environment and human life. Around 14 solar cosmic ray ground level enhancement (GLE) events in solar cycle 23 we examined the cosmic ray variation, solar wind speed, ions density, interplanetary magnetic field, and geomagnetic disturbance storm time index ( Dst). We found that all but one of GLEs are always followed by a geomagnetic storm with Dst ⩽ -50 nT within 1-5 days later. Most(10/14) geomagnetic storms have Dst index ⩽ -100 nT therefore generally belong to strong geomagnetic storms. This suggests that GLE event prediction of geomagnetic storms is 93% for moderate storms and 71% for large storms when geomagnetic storms preceded by GLEs. All Dst depressions are associated with cosmic ray decreases which occur nearly simultaneously with geomagnetic storms. We also investigated the interplanetary plasma features. Most geomagnetic storm correspond significant periods of southward Bz and in close to 80% of the cases that the Bz was first northward then turning southward after storm sudden commencement (SSC). Plasma flow speed, ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival. Solar cause and energetic particle signatures of large geomagnetic storms and a possible prediction scheme are discussed.

  10. Changes in extreme temperature and precipitation events in the Loess Plateau (China) during 1960-2013 under global warming

    Science.gov (United States)

    Sun, Wenyi; Mu, Xingmin; Song, Xiaoyan; Wu, Dan; Cheng, Aifang; Qiu, Bing

    2016-02-01

    In recent decades, extreme climatic events have been a major issue worldwide. Regional assessments on various climates and geographic regions are needed for understanding uncertainties in extreme events' responses to global warming. The objective of this study was to assess the annual and decadal trends in 12 extreme temperature and 10 extreme precipitation indices in terms of intensity, frequency, and duration over the Loess Plateau during 1960-2013. The results indicated that the regionally averaged trends in temperature extremes were consistent with global warming. The occurrence of warm extremes, including summer days (SU), tropical nights (TR), warm days (TX90), and nights (TN90) and a warm spell duration indicator (WSDI), increased by 2.76 (P changes in SDII and CDD occurred in central and southeastern Loess Plateau. However, the changes in days of erosive rainfall, heavy rain, rainstorm, maximum 5-day precipitation, and very-wet-day and extremely wet-day precipitation were not significant. Large-scale atmospheric circulation indices, such as the Western Pacific Subtropical High Intensity Index (WPSHII) and Arctic Oscillation (AO), strongly influences warm/cold extremes and contributes significantly to climate changes in the Loess Plateau. The enhanced geopotential height over the Eurasian continent and increase in water vapor divergence in the rainy season have contributed to the changes of the rapid warming and consecutive drying in the Loess Plateau.

  11. Characterising the Geomorphic Response of a Tropical Mega-River to an Extreme, Cyclone Induced, Flood Event.

    Science.gov (United States)

    Hackney, C. R.; Leyland, J.; Darby, S. E.; Parsons, D. R.; Aalto, R. E.; Nicholas, A. P.; Best, J.

    2014-12-01

    Extreme events have the ability to induce extensive geomorphic change in fluvial systems as a result of elevated discharge levels, increased sediment transport capacity and associated changes in sheer stresses along channel boundaries. Understanding how rapid rises in water levels change flow structures and channel boundary roughness is key to understanding the relative significance of large events in terms of driving local and system wide geomorphic change. However, capturing the fluvial process dynamics in operation during such events is technically and logistically difficult, especially in the world's largest rivers. During September 2013, on the peak of the monsoon, a series of tropical cyclones induced a large flood event within the Mekong basin. At the peak of the flood wave, discharge measured ~60000 m3/s; the 11th largest flood on record. Pre and post event high resolution topographic surveys of parts of the bed and bank were captured using a combination of contiguous multibeam echo sounding (MBES) and terrestrial laser scanning (TLS) during the event. Simultaneously detailed measurements of cross sectional and near bank flow structure were acquired using an acoustic Doppler current profiler (aDcp). Together, these unique datasets can be used to characterise and assess the geomorphic impact of a cyclone induced extreme flood event on the Mekong. We show how flow structures in the near bank region evolve with stage during the extreme event and how the associated geomorphic response is modulated by the distinctive process dynamics of a mega-river.

  12. A spatiotemporal analysis of participatory sensing data "tweets" and extreme climate events toward real-time urban risk management

    OpenAIRE

    Yamagata, Yoshiki; Murakami, Daisuke; Peters, Gareth W.; Matsui, Tomoko

    2015-01-01

    Real-time urban climate monitoring provides useful information that can be utilized to help monitor and adapt to extreme events, including urban heatwaves. Typical approaches to the monitoring of climate data include weather station monitoring and remote sensing. However, climate monitoring stations are very often distributed spatially in a sparse manner, and consequently, this has a significant impact on the ability to reveal exposure risks due to extreme climates at an intra-urban scale. Ad...

  13. Widespread extreme drought events in Iberia and their relationship with North Atlantic moisture flux deficit

    Science.gov (United States)

    Liberato, Margarida L. R.; Montero, Irene; Russo, Ana; Gouveia, Célia; Ramos, Alexandre M.; Trigo, Ricardo M.

    2015-04-01

    Droughts represent one of the most frequent climatic extreme events on the Iberian Peninsula, often with widespread negative ecological and environmental impacts, resulting in major socio-economic damages such as large decreases in hydroelectricity and agricultural productions or increasing forest fire risk. Unlike other weather driven extreme events, droughts duration could be from few months to several years. Here we employ a recently developed climatic drought index, the Standardized Precipitation Evapotranspiration Index (SPEI; Vicente-Serrano et al. 2010a), based on the simultaneous use of precipitation and temperature fields. This index holds the advantage of combining a multi-scalar character with the capacity to include the effects of temperature variability on drought assessment (Vicente-Serrano et al., 2010a). In this study the SPEI was computed using the Climatic Research Unit (CRU) TS3.21 High Resolution Gridded Data (0.5°) for the period 1901-2012. At this resolution the study region of Iberian Peninsula corresponds to a square of 30x30 grid pixels. The CRU Potential Evapotranspiration (PET) was used, through the Penmann-Monteith equation and the log-logistic probability distribution. This formulation allows a very good fit to the series of differences between precipitation and PET (Vicente-Serrano et al., 2010b), using monthly averages of daily maximum and minimum temperature data and also monthly precipitation records. The parameters were estimated by means of the L-moment method. The application of multi-scalar indices to the high-resolution datasets allows identifying whether the Iberian Peninsula is in hydric stress and also whether drought is installed. Based on the gridded SPEI datasets, spanning from 1901 to 2012, obtained for timescales 6, 12, 18 and 24 months, an objective method is applied for ranking the most extensive extreme drought events that occurred on the Iberian Peninsula. This objective method is based on the evaluation of the

  14. How extreme weather events can influence the way of thinking about forest management?

    Science.gov (United States)

    Ziemblińska, Klaudia; Merbold, Lutz; Urbaniak, Marek; Haeni, Matthias; Olejnik, Janusz

    2014-05-01

    One third of the total area of Poland, which is covered by forests, is currently managed by "The State National Forest Holding" - the biggest organization in Europe managing forests. Common management practice is based on clear-cutting the vegetation to maintaining forests and ensuring regrowth. While sufficient information exists on the quantity of harvested biomass and particularly its economic value, little knowledge exists on the overall environmental impact of such management including the carbon budgets of forests in Poland. At the same time these forests are very vulnerable to extreme events such as wind throws. Large wind throws can be used as an experimental platform to study both, the effects of extreme events itself but also the effects of management such as clear-cuts, due to the fact that after such kind of natural disasters similar steps then following clear-cuts are implemented. These activities include the removal of whole trees, collection of branches and pulling out stems with heavy machinery, causing additional disturbance. In this study, we aim at providing information to fill the current knowledge gap of changing C budget after clear-cuts and wind throws. We hypothesize large C losses after clear-cuts and ask whether one can improve current forest management to "save" C and/or enhance C sequestration? To answer this specific question we used the eddy covariance (EC) method to adequately measure the net ecosystem exchange of carbon dioxide (NEE) between a deforested area and the atmosphere (treatment) and compare it to measurements from an intact forest of the same type (control). Both sites have the same soil type (brunic arenosoil - after FAO classification) which is sandy and relatively not fertile. Moreover, main species and composition were similar. The treatment area was chosen after the occurrence of a 20min-lasting tornado in July 2012 in Western Poland. The storm resulted in the destruction of more than 500 ha of 75-year old pine forest

  15. Boulder accumulations related to extreme wave events on the eastern coast of Malta

    Science.gov (United States)

    Biolchi, S.; Furlani, S.; Antonioli, F.; Baldassini, N.; Causon Deguara, J.; Devoto, S.; Di Stefano, A.; Evans, J.; Gambin, T.; Gauci, R.; Mastronuzzi, G.; Monaco, C.; Scicchitano, G.

    2015-10-01

    The accumulation of large boulders related to waves generated either by tsunamis or extreme storm events has been observed in different areas of the Mediterranean Sea. Along the NE and E low-lying rocky coasts of Malta tens of large boulder deposits have been surveyed, measured and mapped. These boulders have been detached and moved from the seafloor and lowest parts of the coast by the action of sea waves. In the Sicily-Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few severe earthquakes and tsunamis are recorded in historical documents to have hit the Maltese archipelago, originated by seismicity activity related mainly to the Malta Escarpment, the Sicily Channel Rift Zone and the Hellenic Arc. We present a multi-disciplinary study, which aims to define the characteristics of the boulder accumulations along the eastern coast of Malta, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland. The wave heights required to transport coastal boulders were calculated using various hydrodynamic equations. Particular attention was devoted to the quantification of the input parameters required in the workings of these equations. The axis sizes of blocks were measured with 3-D digital photogrammetric techniques and their densities were obtained throughout the use of a N-type Schmidt Hammer. Moreover, AMS ages were obtained from selected marine organisms encrusted on some of the boulders in various coastal sites. The combination of the results obtained by hydrodynamic equations and the radiocarbon dating suggests that the majority of the boulders has been detached and moved by intense storm waves. Nonetheless, it is possible that some of them may have been transported by tsunami.

  16. Extreme events: the implication for dredging and navigability of the Lower Niger River

    International Nuclear Information System (INIS)

    Sustainable development of water resources for transportation and other developmental activities requires an assessment of the complex relationships between a variety of environmental and hydrological processes across space and time. The economic benefits of dredging large river body for inland river navigation can only be realized if there is adequate water depth and where the hydro-climatic dynamics generate much water to sustain the high water level year round. The extreme water level is particularly critical to the Lower Niger River given the fact that the least available depth (LAD) of three meters is required for sustaining medium and relatively large shipping activities year round across the 690 km length of the lower Niger River. Based on statistical analysis at 95% level of significance, a 10% increase in the runoff generated was calculated for the wet season months while 5% increase was calculated for the dry season months as the expected runoff after dredging and deforestation. The event of the least available depth (LAD) was critically examine using Newton's gravitational model of Manning equation for water depth analysis as well as water level duration analysis. The water level duration curves were used to determine the least available depth (LAD) for three stations (Onitsha, Lokoja and Baro) along the Lower Niger River. Although the two extremes of minimum and maximum depths and the fluctuations within were critical for the usage of any river for shipping economic activities,it was however, found that the on going dredging of the Lower Niger River would only marginally meets the required LAD for few months within a year and this will reduce from downstream to upstream along the water course.(Author)

  17. A new strategy for sensitivity analysis when modelling extreme events in the geosciences

    Science.gov (United States)

    Pianosi, Francesca; Wagener, Thorsten

    2014-05-01

    Natural hazard models - used to predict and evaluate extreme events like prolonged droughts, floods, windstorms, etc. - are affected by unavoidable and potentially large uncertainty. Uncertainty sources are manifold, including simplifying assumptions in the model structure (e.g. coarse spatial resolution), uncertain parameter values, measurement errors, etc. Global Sensitivity Analysis (GSA) can be used to assess the relative contributions from these different sources to the uncertainty in the model predictions. By providing insights into the model behavior and potential for simplification, GSA indicates where further data collection and research is needed or would be beneficial, and enhances the credibility of the modelling results. In this work we present a novel Regional-Global approach for Sensitivity Analysis. The method is "global" in the model inputs and "regional" in the output, that is, it considers variations of the uncertain inputs across their entire feasibility range but can be focused on their effects on a specific region of the model response, e.g. extreme values. The method is therefore especially promising for natural hazard applications where the focus in on the effect of uncertain inputs on specific range of values of the model output. The main underlying idea is to measure sensitivity by the distance between the unconditional distribution of the model output (i.e. when all input factors vary) and the conditional distribution when one of the input factors is fixed. Such sensitivity measures can be computed either over the entire range of the output distribution or tuned to consider only a sub-range, for instance the tail of the distribution. We use several natural hazards examples to demonstrate the approach and compare it to other widely applied GSA methods like Sobol and Regional Sensitivity Analysis.

  18. Boulder accumulations related to extreme wave events on the eastern coast of Malta

    Science.gov (United States)

    Biolchi, Sara; Furlani, Stefano; Antonioli, Fabrizio; Baldassini, Niccoló; Causon Deguara, Joanna; Devoto, Stefano; Di Stefano, Agata; Evans, Julian; Gambin, Timothy; Gauci, Ritienne; Mastronuzzi, Giuseppe; Monaco, Carmelo; Scicchitano, Giovanni

    2016-03-01

    The accumulation of large boulders related to waves generated by either tsunamis or extreme storm events have been observed in different areas of the Mediterranean Sea. Along the eastern low-lying rocky coasts of Malta, five sites with large boulder deposits have been investigated, measured and mapped. These boulders have been detached and moved from the nearshore and the lowest parts of the coast by sea wave action. In the Sicily-Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few tsunamis have been recorded in historical documents to have reached the Maltese archipelago. We present a multi-disciplinary study, which aims to define the characteristics of these boulder accumulations, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland. The wave heights required to transport 77 coastal boulders were calculated using various hydrodynamic equations. Particular attention was given to the quantification of the input parameters required in the workings of these equations, such as size, density and distance from the coast. In addition, accelerator mass spectrometry (AMS) 14C ages were determined from selected samples of marine organisms encrusted on some of the coastal boulders. The combination of the results obtained both by the hydrodynamic equations, which provided values comparable with those observed and measured during the storms, and radiocarbon dating suggests that the majority of the boulders have been detached and moved by intense storm waves. These boulders testify to the existence of a real hazard for the coasts of Malta, i.e. that of very high storm waves, which, during exceptional storms, are able to detach large blocks of volumes exceeding 10 m3 from the coastal edge and the nearshore bottom, and also to transport them inland. Nevertheless, the occurrence of one or more tsunami events cannot be ruled out, since

  19. Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007

    Directory of Open Access Journals (Sweden)

    S. Rusjan

    2009-06-01

    Full Text Available During a weather front that passed over large parts of Slovenia on 18.9.2007, extreme rainfall events were triggered causing several severe flash floods with six casualties. Out of 210 municipalities in Slovenia, 60 were reporting flood damages, and the total economic flood damage was later estimated at close to 200 million Euro; highest damage was claimed by Železniki municipality in NW Slovenia. The main purpose of the study presented in this paper was to put together available meteorological and hydrological data in order to get better insight into temporal and spatial dynamics and variability of the flash flood event along the Selška Sora River flowing through the town of Železniki. The weather forecast by the Environmental Agency of the Republic of Slovenia (ARSO lead to early warning of floodings but has underestimated rainfall amounts by a factor of 2. Also meteorological radar underestimated ground rainfall as much as by 50%. During that day, in many rainfall gauging stations operated by ARSO in the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm in 24 h or 157 mm in 2 h. Some of the measured rainfall amounts were the highest registered amounts in Slovenia so far. Statistical analysis using Gumble distribution was performed and rainfall return periods were estimated. When assessing rainfall return periods, a question of the sampling error as a consequence of short rainfall records used was raised. Furthermore, measured rainfall data were used to reconstruct hydrographs on selected water stations along the Selška Sora River. The cumulative areal precipitation for the Selška Sora River catchment upstream of Železniki amounted to 219 mm, while the modeled effective precipitation used to simulate the hydrograph peak was only 57 mm. The modeled direct runoff coefficient therefore amounts to 0.26. Surprisingly low value is mainly caused by the applied unit hydrograph method that seeks to meet the peak

  20. Impacts of extreme weather events on highly eutrophic marine ecosystem (Rogoznica Lake, Adriatic coast)

    Science.gov (United States)

    Ciglenečki, I.; Janeković, I.; Marguš, M.; Bura-Nakić, E.; Carić, M.; Ljubešić, Z.; Batistić, M.; Hrustić, E.; Dupčić, I.; Garić, R.

    2015-10-01

    Rogoznica Lake is highly eutrophic marine system located on the Eastern Adriatic coast (43°32‧N, 15°58‧E). Because of the relatively small size (10,276 m2) and depth (15 m) it experiences strong natural and indirect anthropogenic influences. Dynamics within the lake is characterized by the extreme and highly variable environmental conditions (seasonal variations in salinity and temperature, water stratification and mixing, redox and euxinic conditions, concentrations of nutrients) which significantly influence the biology inside the lake. Due to the high phytoplankton activity, the upper part of the water column is well oxygenated, while hypoxia/anoxia usually occurs in the bottom layers. Anoxic part of the water column is characterized with high concentrations of sulfide (up to 5 mM) and nutrients (NH4+ up to 315 μM; PO43- up to 53 μM; SiO44- up to 680 μM) indicating the pronounced remineralization of the allochthonous organic matter, produced in the surface waters. The mixolimnion varies significantly within a season feeling effects of the Adriatic atmospheric and ocean dynamics (temperature, wind, heat fluxes, rainfall) which all affect the vertical stability and possibly induce vertical mixing and/or turnover. Seasonal vertical mixing usually occurs during the autumn/winter upon the breakdown of the stratification, injecting oxygen-rich water from the surface into the deeper layers. Depending on the intensity and duration of the vertical dynamics (slower diffusion and/or faster turnover of the water layers) anoxic conditions could developed within the whole water column. Extreme weather events such as abrupt change in the air temperature accompanied with a strong wind and consequently heat flux are found to be a key triggering mechanism for the fast turnover, introducing a large amount of nutrients and sulfur species from deeper parts to the surface. Increased concentration of nutrients, especially ammonium, phosphate, and silicates persisting for

  1. Climate-related disaster opens a window of opportunity for rural poor in northeastern Honduras.

    Science.gov (United States)

    McSweeney, Kendra; Coomes, Oliver T

    2011-03-29

    Two distinct views are evident in research on how rural communities in developing countries cope with extreme weather events brought by climate change: (i) that the resource-reliant poor are acutely vulnerable and need external assistance to prepare for such events, and (ii) that climate-related shocks can offer windows of opportunity in which latent local adaptive capacities are triggered, leading to systemic improvement. Results from a longitudinal study in a Tawahka community in Honduras before and after Hurricane Mitch (1994-2002) indicate that residents were highly vulnerable to the hurricane--due in part to previous development assistance--and that the poorest households were the hardest hit. Surprisingly, however, the disaster enabled the poor to initiate an institutional change that led to more equitable land distribution, slowed primary forest conversion, and positioned the community well to cope with comparable flooding occurring 10 y later. The study provides compelling evidence that communities can seize on the window of opportunity created by climate-induced shocks to generate sustained social-ecological improvement, and suggests that future interventions should foster local capacities for endogenous institutional change to enhance community resilience to climate shocks. PMID:21402909

  2. The effects of climatic fluctuations and extreme events on running water ecosystems

    Science.gov (United States)

    Woodward, Guy; Bonada, Núria; Brown, Lee E.; Death, Russell G.; Durance, Isabelle; Gray, Clare; Hladyz, Sally; Ledger, Mark E.; Milner, Alexander M.; Ormerod, Steve J.; Thompson, Ross M.

    2016-01-01

    Most research on the effects of environmental change in freshwaters has focused on incremental changes in average conditions, rather than fluctuations or extreme events such as heatwaves, cold snaps, droughts, floods or wildfires, which may have even more profound consequences. Such events are commonly predicted to increase in frequency, intensity and duration with global climate change, with many systems being exposed to conditions with no recent historical precedent. We propose a mechanistic framework for predicting potential impacts of environmental fluctuations on running-water ecosystems by scaling up effects of fluctuations from individuals to entire ecosystems. This framework requires integration of four key components: effects of the environment on individual metabolism, metabolic and biomechanical constraints on fluctuating species interactions, assembly dynamics of local food webs, and mapping the dynamics of the meta-community onto ecosystem function. We illustrate the framework by developing a mathematical model of environmental fluctuations on dynamically assembling food webs. We highlight (currently limited) empirical evidence for emerging insights and theoretical predictions. For example, widely supported predictions about the effects of environmental fluctuations are: high vulnerability of species with high per capita metabolic demands such as large-bodied ones at the top of food webs; simplification of food web network structure and impaired energetic transfer efficiency; and reduced resilience and top-down relative to bottom-up regulation of food web and ecosystem processes. We conclude by identifying key questions and challenges that need to be addressed to develop more accurate and predictive bio-assessments of the effects of fluctuations, and implications of fluctuations for management practices in an increasingly uncertain world. PMID:27114576

  3. The effects of climatic fluctuations and extreme events on running water ecosystems.

    Science.gov (United States)

    Woodward, Guy; Bonada, Núria; Brown, Lee E; Death, Russell G; Durance, Isabelle; Gray, Clare; Hladyz, Sally; Ledger, Mark E; Milner, Alexander M; Ormerod, Steve J; Thompson, Ross M; Pawar, Samraat

    2016-05-19

    Most research on the effects of environmental change in freshwaters has focused on incremental changes in average conditions, rather than fluctuations or extreme events such as heatwaves, cold snaps, droughts, floods or wildfires, which may have even more profound consequences. Such events are commonly predicted to increase in frequency, intensity and duration with global climate change, with many systems being exposed to conditions with no recent historical precedent. We propose a mechanistic framework for predicting potential impacts of environmental fluctuations on running-water ecosystems by scaling up effects of fluctuations from individuals to entire ecosystems. This framework requires integration of four key components: effects of the environment on individual metabolism, metabolic and biomechanical constraints on fluctuating species interactions, assembly dynamics of local food webs, and mapping the dynamics of the meta-community onto ecosystem function. We illustrate the framework by developing a mathematical model of environmental fluctuations on dynamically assembling food webs. We highlight (currently limited) empirical evidence for emerging insights and theoretical predictions. For example, widely supported predictions about the effects of environmental fluctuations are: high vulnerability of species with high per capita metabolic demands such as large-bodied ones at the top of food webs; simplification of food web network structure and impaired energetic transfer efficiency; and reduced resilience and top-down relative to bottom-up regulation of food web and ecosystem processes. We conclude by identifying key questions and challenges that need to be addressed to develop more accurate and predictive bio-assessments of the effects of fluctuations, and implications of fluctuations for management practices in an increasingly uncertain world. PMID:27114576

  4. An extreme event of sea-level rise along the Northeast Coast of North America in 2009-2010.

    Science.gov (United States)

    Goddard, Paul B; Yin, Jianjun; Griffies, Stephen M; Zhang, Shaoqing

    2015-01-01

    The coastal sea levels along the Northeast Coast of North America show significant year-to-year fluctuations in a general upward trend. The analysis of long-term tide gauge records identified an extreme sea-level rise (SLR) event during 2009-10. Within this 2-year period, the coastal sea level north of New York City jumped by 128 mm. This magnitude of interannual SLR is unprecedented (a 1-in-850 year event) during the entire history of the tide gauge records. Here we show that this extreme SLR event is a combined effect of two factors: an observed 30% downturn of the Atlantic meridional overturning circulation during 2009-10, and a significant negative North Atlantic Oscillation index. The extreme nature of the 2009-10 SLR event suggests that such a significant downturn of the Atlantic overturning circulation is very unusual. During the twenty-first century, climate models project an increase in magnitude and frequency of extreme interannual SLR events along this densely populated coast. PMID:25710720

  5. Learning from today's extreme weather events to increase our resilience to climate change

    Science.gov (United States)

    Ruin, I.; Lutoff, C.; Borga, M.; Creutin, J.-D.; Anquetin, S.; Gruntfest, E.; Scolobig, A.

    2009-04-01

    According to the IPCC, flooding is the most widespread serious potential impact of climate change on human settlement. Vulnerability to floods can be thought as a function of exposure and adaptive capacity, and all three entities have been increasing in many areas. Therefore, in order to inform decision-makers, it is crucial to better understand what are the vulnerability factors but also to what extend individuals and societies are capable to adapt their way of life to their changing environment. In this perspective, flash flood events offer a good example of the kind of extremes that our societies may have to face more often in the future. Characterized by their suddenness, fast and violent movement, rarity and small scale, they are particularly difficult to forecast accurately and leave very little lead-time for warnings. In this context, our interdisciplinary team conducts research focusing on individual and human organization responses to warning and crisis situations by using a comprehensive, coupled natural—human system approach over time and space scales. The objective is to understand i) what cognitive and situational factors help individuals and communities to shift from normal daily activities to adapted crisis response and ii) what is the dynamic of this process compared to the one of the natural phenomenon. In this regard, our research learned both from individual perception and behavioral intent survey ("what if" type of survey) than from actual behavioral data gathered in a context of post-event investigations. The review of the literature shows that behavioral intent surveys do not accurately predict warning and crisis response as well as behavioral data do. Knowing that, the difficulty is to obtain consistent and accurate spatio-temporal behavioral data. According to our experience, this is particularly difficult in the context of crisis situations. Behavioral verification requires real-time observations and data collection of indicators

  6. Extreme Violation of Sleep Hygiene: Sleeping Against the Biological Clock During a Multiday Relay Event

    Directory of Open Access Journals (Sweden)

    van Maanen

    2015-12-01

    Full Text Available Background Sleep hygiene is important for sleep quality and optimal performance during the day. However, it is not always possible to follow sleep hygiene requirements. In multiday relay events, athletes have to sleep immediately after physical exertion and sometimes against their biological clock. Objectives In this pilot study we investigated the effect of having to sleep at an abnormal circadian time on sleep duration. Patients and Methods Eight runners and two cyclists performing a 500 km relay race were followed. They were divided into two groups that took turns in running and resting. Each group ran four times for approximately five hours while the other group slept. As a result, sleep times varied between normal and abnormal times. All athletes wore actigraphs to record the duration and onset of sleep. Results Linear mixed model analyses showed that athletes slept on average 43 minutes longer when they slept during usual (night times than during abnormal (day times. In general, sleep duration decreased during the race with on average 18 minutes per period. Conclusions This pilot study shows that, even under extreme violation of sleep hygiene rules, there still is an apparent effect of circadian rhythm on sleep duration in relay race athletes.

  7. Short-term cropland responses to temperature extreme events during late winter

    Directory of Open Access Journals (Sweden)

    G. De Simon

    2013-04-01

    Full Text Available In recent years, several studies have focused on terrestrial ecosystem response to extreme events. Most of this research has been conducted in natural ecosystems, but few have considered agro-ecosystems. In this study, we investigated the impact of a manipulated warmer or cooler late winter-early spring on the carbon budget and final harvest of a soybean crop (Glycine max (L. Merr.. Soil temperature was altered by manipulating soil albedo by covering the soil surface with a layer of inert silica gravel. We tested three treatments: cooling (Co, warming (W, mix (M and control (C. An automated system continuously measured soil heterotrophic respiration (Rh, soil temperature profiles, and soil water content across the entire year in each plot. Phenological phases were periodically assessed and final harvest was measured in each plot. Results showed that treatments had only a transient effect on daily Rh rates which did not result in a total annual carbon budget significantly different from control, even though cooling showed a significant reduction in final harvest. We also observed anticipation in seed germination in both W and M treatments and a delay in germination for Co. Moreover, plant density and growth increased in W and M and decreased in Co.

  8. NASA Contributions to Improve Understanding of Extreme Events in the Global Energy and Water Cycle

    Science.gov (United States)

    Lapenta, William M.

    2008-01-01

    The U.S. Climate Change Science Program (CCSP) has established the water cycle goals of the Nation's climate change program. Accomplishing these goals will require, in part, an accurate accounting of the key reservoirs and fluxes associated with the global water and energy cycle, including their spatial and temporal variability. through integration of all necessary observations and research tools, To this end, in conjunction with NASA's Earth science research strategy, the overarching long-term NASA Energy and Water Cycle Study (NEWS) grand challenge can he summarized as documenting and enabling improved, observationally based, predictions of water and energy cycle consequences of Earth system variability and change. This challenge requires documenting and predicting trends in the rate of the Earth's water and energy cycling that corresponds to climate change and changes in the frequency and intensity of naturally occurring related meteorological and hydrologic events, which may vary as climate may vary in the future. The cycling of water and energy has obvious and significant implications for the health and prosperity of our society. The importance of documenting and predicting water and energy cycle variations and extremes is necessary to accomplish this benefit to society.

  9. Short-term cropland responses to temperature extreme events during late winter

    Directory of Open Access Journals (Sweden)

    G. De Simon

    2013-08-01

    Full Text Available In recent years, several studies have focused on terrestrial ecosystem response to extreme events. Most of this research has been conducted in natural ecosystems, but few have considered agroecosystems. In this study, we investigated the impact of a manipulated warmer or cooler late winter/early spring on the carbon budget and final harvest of a soybean crop (Glycine max (L. Merr.. Soil temperature was altered by manipulating soil albedo by covering the soil surface with a layer of inert silica gravel. We tested three treatments – cooling (Co, warming (W, mix (M – and control (C. An automated system continuously measured soil heterotrophic respiration (Rh, soil temperature profiles, and soil water content across the entire year in each plot. Phenological phases were periodically assessed and final harvest was measured in each plot. Results showed that treatments had only a transient effect on daily Rh rates, which did not result in a total annual carbon budget significantly different from control, even though cooling showed a significant reduction in final harvest. We also observed anticipation in emergence in both W and M treatments and a delay in emergence for Co. Moreover, plant density and growth increased in W and M and decreased in Co. In conclusion, from the results of our experiment we can assert that an increase in the frequency of both heat and cold waves is unlikely to have large effects on the overall annual carbon balance of irrigated croplands.

  10. Modelling extreme flood hazard events on the middle Yellow River using DFLOW-flexible mesh approach

    Directory of Open Access Journals (Sweden)

    M. Castro Gama

    2013-11-01

    DFLOW-FMβeta gives the opportunity to enhance the understanding of the behavior of the Yellow River during extreme events. The modeling approaches based on discretization of the modeled domain in square and rectangular grids have a great importance in the management of rivers but usually they present two drawbacks: the required accuracy of the meandering of wide long rivers is not well represented, and the reduced speed in computational runtime due to the need of using many grid cells. A new tool, developed by Deltares, based on a flexible mesh discretization of the domain, presents the advantage that the two drawbacks can be overcome. The approach has the advantage of combining different grids, in order to properly represent the river and compute the flooding extent accurately. The method is checked and demonstrated on the Yellow River case. Along with the test of the new proposed modeling method new characteristics of the spatial flooding process in the Yellow River emerges and are presented in the paper, showing the capabilities of the software application tool in modeling such a complex environment like the one studied.

  11. Property damage recovery and coping behavior of households affected by an extreme flood event in Marikina City, Metro Manila, Philippines

    OpenAIRE

    JAMIL PAOLO S. FRANCISCO

    2015-01-01

    This study identifies the factors influencing household choice of coping strategy to an extreme flood event in Marikina City in the National Capital Region of the Philippines, as well as household recovery after the event, measured in terms of the length of time to repair, rebuild, or replace damaged property. A survey of 400 households was conducted to obtain data. A multinomial logistic model was used to analyze coping strategy choice among three possible alternatives: (1) reactive and shor...

  12. Plant phenological responses to extreme events - A long term perspective from the Chihuahuan Desert

    Science.gov (United States)

    Browning, D. M.; Peters, D. P.; Anderson, J.; Yao, J.

    2011-12-01

    Arid and semi-arid regions of the southwestern USA are especially sensitive to changes in temperature as well as drought frequency and intensity. Timing of periodic life cycle events (i.e., phenology) is an integrated and salient indicator of plant responses to climate change. We examine an 18-year dataset of monthly observations of plant phenology for two species of perennial grasses and a deciduous shrub (honey mesquite) distributed across three upland grassland sites and three mesquite-dominated sites on the Jornada Basin USDA-LTER in southern New Mexico, USA. Precipitation is highly variable between years and across space. Long-term phenology data collection spanned a multi-year drought (1994-2003) followed by a sequence of years with average to very high rainfall (2004 - 2008). Our objective was to compare and contrast responses to extreme dry and wet cycles in the timing and duration of first leaf and fruit production for two grasses (Bouteloua eriopoda [black grama], Sporobolus flexuosus [mesa dropseed]) with one co-existing shrub that has displaced grasses in this system (Prosopis glandulosa [honey mesquite]). Monthly field observations yield estimates of phenological status and abundance for 18 growing seasons from 1993 to 2010. All three species most commonly initiated new growth prior to onset of the monsoon rains (March or April). Timing of first growth for mesquite was less variable (standard deviation = 0.47) than for black grama (SD = 1.42) and mesa dropseed (SD = 1.22) grasses. Initial growth for grasses was delayed to September in 2006 following twelve months of deficit values for PDSI. The appearance of first fruit for grasses occurred consistently in August or September, although the number of plants producing fruit was highly variable from year to year. The largest numbers of fruit-bearing grasses were observed in late fall 2008 in response to heavy monsoon rains in 2006 and 2008. Mesquite demonstrated remarkable synchrony in the production of

  13. Natural disasters and the challenge of extreme events: risk management from an insurance perspective

    Science.gov (United States)

    Smolka, Anselm

    2006-08-01

    an acceptable level. Due to the rarity of such extreme events, specific risk prevention measures are hardly justified with exception of attempts to divert earth-orbit crossing meteorites from their dangerous path. For the industry it is particularly important to achieve full transparency as regards covered and non-covered risks and to define in a systematic manner the limits of insurability for super-disasters.

  14. Simulations of The Extreme Precipitation Event Enhanced by Sea Surface Temperature Anomaly over the Black Sea

    Science.gov (United States)

    Hakan Doǧan, Onur; Önol, Barış

    2016-04-01

    Istanbul Technical University, Aeronautics and Astronautics Faculty, Meteorological Engineering, Istanbul, Turkey In this study, we examined the extreme precipitation case over the Eastern Black Sea region of Turkey by using regional climate model, RegCM4. The flood caused by excessive rain in August 26, 2010 killed 12 people and the landslides in Rize province have damaged many buildings. The station based two days total precipitation exceeds 200 mm. One of the usual suspects for this extreme event is positive anomaly of sea surface temperature (SST) over the Black Sea where the significant warming trend is clear in the last three decades. In August 2010, the monthly mean SST is higher than 3 °C with respect to the period of 1981-2010. We designed three sensitivity simulations with RegCM4 to define the effects of the Black Sea as a moisture source. The simulation domain with 10-km horizontal resolution covers all the countries bordering the Black Sea and simulation period is defined for entire August 2010. It is also noted that the spatial variability of the precipitation produced by the reference simulation (Sim-0) is consistent with the TRMM data. In terms of analysis of the sensitivity to SST, we forced the simulations by subtracting 1 °C (Sim-1), 2 °C (Sim-2) and 3 °C (Sim-3) from the ERA-Interim 6-hourly SST data (considering only the Black Sea). The sensitivity simulations indicate that daily total precipitation for all these simulations gradually decreased based on the reference simulation (Sim-0). 3-hourly maximum precipitation rates for Sim-0, Sim-1, Sim-2 and Sim-3 are 32, 25, 13 and 10.5 mm respectively over the hotspot region. Despite the fact that the simulations signal points out the same direction, degradation of the precipitation intensity does not indicate the same magnitude for all simulations. It is revealed that 2 °C (Sim-2) threshold is critical for SST sensitivity. We also calculated the humidity differences from the simulation and these

  15. Spatial analysis and modeling to assess and map current vulnerability to extreme weather events in the Grijalva - Usumacinta watershed, Mexico

    International Nuclear Information System (INIS)

    One of the major concerns over a potential change in climate is that it will cause an increase in extreme weather events. In Mexico, the exposure factors as well as the vulnerability to the extreme weather events have increased during the last three or four decades. In this study spatial analysis and modeling were used to assess and map settlement and crop systems vulnerability to extreme weather events in the Grijalva - Usumacinta watershed. Sensitivity and coping adaptive capacity maps were constructed using decision models; these maps were then combined to produce vulnerability maps. The most vulnerable area in terms of both settlement and crop systems is the highlands, where the sensitivity is high and the adaptive capacity is low. In lowlands, despite the very high sensitivity, the higher adaptive capacity produces only moderate vulnerability. I conclude that spatial analysis and modeling are powerful tools to assess and map vulnerability. These preliminary results can guide the formulation of adaptation policies to an increasing risk of extreme weather events.

  16. Features of the extreme events observed in the all-solid state laser with a saturable absorber

    CERN Document Server

    Bonazzola, Carlos R; Kovalsky, Marcelo G; Tredicce, Jorge R

    2015-01-01

    Extreme events (sometimes also called optical rogue waves), in the form of pulses of extraordinary intensity, are easily observed in its chaotic regime if the Fresnel number of the cavity is high. This result suggests that the nonlinear interaction among transverse modes is an essential ingredient in the formation of extreme events in this type of lasers, but there is no theoretical description of the phenomenon yet. We report here a set of experimental results on the regularities of these extreme events, to provide a basis for the development of such a description. Among these results, we point out here: i) the decay of the correlation across the transversal section of the laser beam, and ii) the appearance of extreme events even if the time elapsed since the previous pulse is relatively short (in terms of the average inter-pulse separation), what indicates the existence of some unknown mechanism of energy storage. We hypothesize that this mechanism is related with the imperfect depletion of the gain by some...

  17. Acclimation responses to temperature vary with vertical stratification: implications for vulnerability of soil-dwelling species to extreme temperature events

    NARCIS (Netherlands)

    Dooremalen, van C.; Berg, M.P.; Ellers, J.

    2013-01-01

    The occurrence of summer heat waves is predicted to increase in amplitude and frequency in the near future, but the consequences of such extreme events are largely unknown, especially for belowground organisms. Soil organisms usually exhibit strong vertical stratification, resulting in more frequent

  18. Emergence of extreme events in fiber-based parametric processes driven by a partially incoherent pump wave.

    Science.gov (United States)

    Hammani, Kamal; Finot, Christophe; Millot, Guy

    2009-04-15

    We present experimental and theoretical results showing efficient emergence of rogue wavelike extreme intensity spikes during the fiber-based induced-modulational instability process driven by a partially incoherent pump. In particular, we show that the rogue event probability can be easily controlled by adjusting the pump-signal detuning. PMID:19370096

  19. Identifying hydro-meteorological events from precipitation extremes indices and other sources over northern Namibia, Cuvelai Basin

    Directory of Open Access Journals (Sweden)

    Frans C. Persendt

    2015-02-01

    Full Text Available Worldwide, more than 40% of all natural hazards and about half of all deaths are the result of flood disasters. In northern Namibia flood disasters have increased dramatically over the past half-century, along with associated economic losses and fatalities. There is a growing concern to identify these extreme precipitation events that result in many hydro-meteorological disasters. This study presents an up to date and broad analysis of the trends of hydrometeorological events using extreme daily precipitation indices, daily precipitation data from the Grootfontein rainfall station (1917–present, regionally averaged climatologies from the gauged gridded Climate Research Unit (CRU product, archived disasters by global disaster databases, published disaster events in literature as well as events listed by Mendelsohn, Jarvis and Robertson (2013 for the data-sparse Cuvelai river basin (CRB. The listed events that have many missing data gaps were used to reference and validate results obtained from other sources in this study. A suite of ten climate change extreme precipitation indices derived from daily precipitation data (Grootfontein rainfall station, were calculated and analysed. The results in this study highlighted years that had major hydro-meteorological events during periods where no data are available. Furthermore, the results underlined decrease in both the annual precipitation as well as the annual total wet days of precipitation, whilst it found increases in the longest annual dry spell indicating more extreme dry seasons. These findings can help to improve flood risk management policies by providing timely information on historic hydro-meteorological hazard events that are essential for early warning and forecasting.

  20. Extreme drought event and shrub invasion combine to reduce ecosystem functioning and resilience in water-limited climates

    Science.gov (United States)

    Caldeira, Maria; Lecomte, Xavier; David, Teresa; Pinto, Joaquim; Bugalho, Miguel; Werner, Christiane

    2016-04-01

    Extreme droughts and plant invasions are major drivers of global change that can critically affect ecosystem functioning. Shrub encroachment is increasing in many regions worldwide and extreme events are projected to increase in frequency and intensity, namely in the Mediterranean region. Nevertheless, little is known about how these drivers may interact and affect ecosystem functioning and resilience to extreme droughts. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that the native shrub invasion and extreme drought combined to reduce ecosystem transpiration and the resilience of the key-stone oak tree species. We established six 25 x 25 m paired plots in a shrub (Cistus ladanifer L.) encroached Mediterranean cork-oak (Quercus suber L.) woodland. We measured sapflow and pre-dawn leaf water potential of trees and shrubs and soil water content in all plots during three years. We determined the resilience of tree transpiration to evaluate to what extent trees recovered from the extreme drought event. From February to November 2011 we conducted baseline measurements for plot comparison. In November 2011 all the shrubs from one of all the paired plots were cut and removed. Ecosystem transpiration was dominated by the water use of the invasive shrub, which further increased after the extreme drought. Simultaneously, tree transpiration in invaded plots declined much stronger (67 ± 13 %) than in plots cleared from shrubs (31 ± 11%) relative to the pre-drought year. Trees in invaded plots were not able to recover in the following wetter year showing lower resilience to the extreme drought event. Our results imply that in Mediterranean-type of climates invasion by water spending species can combine with projected recurrent extreme droughts causing critical drought tolerance thresholds of trees to be overcome increasing the probability of tree mortality (Caldeira et.al. 2015

  1. Interannual and Intraseasonal oscillations and extreme events over South America simulated by HIGEM models.

    Science.gov (United States)

    Custodio, Maria; Ambrizzi, Tercio

    2014-05-01

    -90 days) timescales using the Fast Fourier Transform (FFT). The occurrence of extreme precipitation and temperature events were analyzed in six sub-regions of SA. The criterion for selection of extremes was based on the quartiles of rainfall anomalies in the bands of interest. The interannual variability analysis showed that coupled simulations intensify the impact of the El Niño Southern Oscillation (ENSO) in the Amazon and southeastern of SA. In the Intraseasonal scale, although the simulations intensify this signal, the coupled models present larger similarities with observations than the atmospheric models for the extremes of precipitation in the SA. Note that there are differences between simulated and observed IS anomalies indicating that the models have problems to correctly represent the intensity of low frequency phenomena in this scale. The simulation of ENSO in GCMs can be attributed to their high resolution, mainly in the oceanic component, which contributes to the better solution of the small scale vortices in the ocean. This implies in improvements in the forecasting of sea surface temperature (SST) and as consequence in the ability of atmosphere to respond to this feature.

  2. Carbon loss and greenhouse gas emission from extreme fire events occurred in Sardinia, Italy

    Science.gov (United States)

    Bacciu, V. M.; Salis, M.; Pellizzaro, G.; Arca, B.; Duce, P.; Spano, D.

    2011-12-01

    It is widely recognized that biomass burning is a significant driver of CO2 cycling and a source of greenhouse gases, aerosol particles, and other chemically reactive atmospheric gases. The large amounts of carbon that fires release into the atmosphere could approach levels of anthropogenic carbon emissions, especially in years of extreme fire activity. CO2 emissions from 2007 forest fires in Greece were in the range of 4.5 Mt, representing about the 4% of the total annual CO2 emissions of that country (http://effis.jrc.it/). Barbosa et al. (2006) reported a similar percentage of fire emissions to total emissions of CO2 in Portugal during the extreme fire seasons of 2003 and 2005. Currently, inventory methods for biomass burning emission use the equation first proposed by Seiler and Crutzen (1980), taking into account the area burned, the amount of biomass burned, and the emission factors associated with each specific chemical species. However, several errors and uncertainties can affect the emission assessment, due to the estimate consistency of the various parameters involved in the equation, including flaming and smoldering combustion periods, appropriate fuel load evaluations and gaseous emission factors for different fuel fractions and fire types. In this context, model approaching can contribute to better appraise fuel consumption and the resultant emissions. In addition, more comprehensive and accurate data inputs would be of valuable help for predicting and quantifying the source and the composition of fire emissions. The purpose of this work is to explore the impacts of extreme fire events occurred in Sardinia Island (Italy) using an integrated approach combining modelling fire emissions, field observations and remotely-sensed data. In order to achieve realistic fire emission estimates, we used the FOFEM model, due to the necessity to use a consistent modeling methodology across source categories, the input required, and its ability to estimate flaming and

  3. The Physical Processes of Eruptive Flares Revealed By An Extremely-Long-Duration Event

    Science.gov (United States)

    Zhang, Jie; Zhou, Zhenjun

    2016-05-01

    In this work, we report the physical processes of eruptive flares inferred from an extremely- long-duration event occurred on June 21, 2011. The flare, peaked at C7.7 level, had a two-hour-long rise time in soft X-rays emission; this rise time is much longer than the typical rise time of solar flares that last for only about ten minutes. Combining the fact that the flare occurred near the disk center as seen by SDO, but near the limbs as seen by STEREO A and B, we are able to track the evolution of the eruption in 3-D as well as in a rare slow-motion manner. The time sequence of temperature maps, constructed from six corona-temperature passbands of AIA, clearly shows process of how the highly-twisted sigmoid structure prior to the eruption is transformed into a near-potential post-eruption loop arcade. The observed sigmoid is likely to be the structure of a twisted magnetic flux rope, which reached a height of about 60 Mm at the onset of the eruption. The onset is likely triggered by the torus instability (or loss of equilibrium) of the flux rope as indicated by the slow rise motion prior to the impulsive phase. We also find that the complex evolution of footprints of the eruption as seen from AIA transition region images is consistent with the magnetic evolution in the corona, which is the consequence of the combined effects of the expansion of the magnetic flux rope and the magnetic reconnection of surrounding magnetic fields.

  4. Hydrodynamic Based Decision Making Framework for Impact Assessment of Extreme Storm Events on Coastal Communities

    Science.gov (United States)

    Nazari, R.; Miller, K.; Hurler, C.

    2015-12-01

    Coastal and inland flooding has been a problematic occurrence, specifically over the past century. Global warming has caused an 8 inch sea level rise since 1990, which made the coastal flood zone wider, deeper and more damaging. Additionally, riverine flooding is extremely damaging to the country's substructure and economy as well which causes river banks to overflow, inundating low-lying areas. New Jersey and New York are two areas at severe risk for flood hazard, sea level rise, land depletion and economic loss which are the main study area of this work. A decision making framework is being built to help mitigate the impacts of the environmental and economical dangers of storm surges, sea level rise, flashfloods and inland flooding. With vigorous research and the use of innovative hydrologic modeling software, this tool can be built and utilized to form resiliency for coastal communities. This will allow the individuals living in a coastal community to understand the details of climatic hazards in their area and risks associated to their communities. This tool will also suggest the best solution for the problem each community faces. Atlantic City and New York City has been modeled and compared using potential storm events and the outcomes have been analyzed. The tool offers all the possible solutions for the type of flooding that occurs. Green infrastructure such as rain gardens, detention basins and green roofs can be used as small scale solutions. Greater scale solutions such as removable flood barriers, concrete walls and height adjustable walls will also be displayed if that poses as the best solution. The results and benefits from the simulation and modeling techniques, will allow coastal communities to choose the most appropriate method for building a long lasting and sustainable resilience plan in the future.

  5. Extreme climatic events: impacts of drought and high temperature on physiological processes in agronomically important plants

    Directory of Open Access Journals (Sweden)

    Urs eFeller

    2014-10-01

    Full Text Available Climate models predict more frequent and more severe extreme events (e.g. heat waves, extended drought periods, flooding in many regions for the next decades. The impact of adverse environmental conditions on crop plants is ecologically and economically relevant. This review is focused on drought and heat effects on physiological status and productivity of agronomically important plants. Stomatal opening represents an important regulatory mechanism during drought and heat stress since it influences simultaneously water loss via transpiration and CO2 diffusion into the leaf apoplast which further is utilized in photosynthesis. Along with the reversible short-term control of stomatal opening, stomata and leaf epidermis may produce waxy deposits and irreversibly down-regulate the stomatal conductance and non-stomatal transpiration. As a consequence photosynthesis will be negatively affected. Rubisco activase - a key enzyme in keeping the Calvin cycle functional – is heat-sensitive and may become a limiting factor at elevated temperature. The accumulated reactive oxygen species during stress represent an additional challenge under unfavorable conditions. Drought and heat cause accumulation of free amino acids which are partially converted into compatible solutes such as proline. This is accompanied by lower rates of both nitrate reduction and de novo amino acid biosynthesis. Protective proteins (e.g. dehydrins, chaperones, antioxidant enzymes or the key enzyme for proline biosynthesis play an important role in leaves and may be present at higher levels under water deprivation or high temperatures. On the whole plant level, effects on long-distance translocation of solutes via xylem and phloem and on leaf senescence (e.g. anticipated, accelerated or delayed senescence are important. The factors mentioned above are relevant for the overall performance of crops under drought and heat and must be considered for genotype selection and breeding programs.

  6. Extreme events in Italy from documentary sources: Venice as a case study

    International Nuclear Information System (INIS)

    Venice risks to be submerged as a consequence of two problems: local land subsidence and sea level rise due to global warming. They both contribute to what is referred as Apparent Sea Level Rise (ASLR). Flooding Tides (locally: Acqua Alta) submerge Venice with an exponentially increasing frequency. The Acqua Alta is generated by a number of factors, the main of them being the Sirocco wind blowing over the Adriatic Sea, that ultimately displaces waters towards Venice. These extreme events have been investigated by using the documentary description of past floods, accurately reported over the last millennium, and tide gauge records for the recent period. A fundamental problem is to know the trend of the ASLR, possibly distinguishing between land subsidence and sea level components. Instrumental data go back to 1872 and a key point is to extend our knowledge back in time. Long-term ASLR has been investigated with the help of a biological indicator, the height of the green belt of the algae that live in the tidal range and whose upper front shows the average high tide level. Fortunately, in the first half of the 18. century, this indicator was accurately drawn by the famous painter Antonio Canaletto (1697-1768) and his pupils, mainly Bernardo Bellotto (1722-1780), in their photographic paintings made with an optical 'camera obscura'. It has been possible to compare the tidal level, as it was in the 1700s and today. After careful spot investigation and minor corrections for some changes to the hydrological system occurred in the meantime, the bulk submersion of Venice estimated from the paintings is 61±11 cm with average yearly trend 1.9 mm y-1

  7. The management of urban surface water flood risks: SUDS performance in flood reduction from extreme events.

    Science.gov (United States)

    Viavattene, C; Ellis, J B

    2013-01-01

    The need to improve the urban drainage network to meet recent urban growth and the redevelopment of old industrial and commercial areas provides an opportunity for managing urban surface water infrastructure in a more sustainable way. The use of sustainable urban drainage systems (SUDS) can reduce urban surface water flooding as well as the pollution impact of urban discharges on receiving waters. However, these techniques are not yet well known by many stakeholders involved in the decision-making process, or at least the evidence of their performance effectiveness may be doubted compared with more traditional engineering solutions often promoted by existing 1D/2D drainage models. The use of geographic information systems (GIS) in facilitating the inter-related risk analysis of sewer surface water overflows and urban flooding as well as in better communication with stakeholders is demonstrated in this paper. An innovative coupled 1D/2D urban sewer/overland flow model has been developed and tested in conjunction with a SUDS selection and location tool (SUDSLOC) to enable a robust management approach to surface water flood risks and to improve the resilience of the urban drainage infrastructure. The paper demonstrates the numerical and modelling basis of the integrated 1D/2D and SUDSLOC approach and the working assumptions and flexibility of the application together with some limitations and uncertainties. The role of the SUDSLOC modelling component in quantifying flow, and surcharge reduction benefits arising from the strategic selection and location of differing SUDS controls are also demonstrated for an extreme storm event scenario. PMID:23128626

  8. Economic Fluctuations and Statistical Physics: Quantifying Extremely Rare and Much Less Rare Events

    Science.gov (United States)

    Stanley, H. Eugene

    2008-03-01

    Recent analysis of truly huge quantities of empirical data suggests that classic economic theories not only fail for a few outliers, but that there occur similar outliers of every possible size. In fact, if one analyzes only a small data set (say 10^4 data points), then outliers appear to occur as ``rare events.'' However, when we analyze orders of magnitude more data (10^8 data points!), we find orders of magnitude more outliers---so ignoring them is not a responsible option, and studying their properties becomes a realistic goal. We find that the statistical properties of these ``outliers'' are identical to the statistical properties of everyday fluctuations. For example, a histogram giving the number of fluctuations of a given magnitude x for fluctuations ranging in magnitude from everyday fluctuations to extremely rare fluctuations that occur with a probability of only 10-8 is a perfect straight line in a double-log plot. Quantitative analogies between financial fluctuations and earthquakes will be discussed. Two unifying principles that underlie much of the finance analysis we will present are scale invariance and universality [R. N. Mantegna and H. E. Stanley, Introduction to Econophysics: Correlations & Complexity in Finance/ (Cambridge U. Press, 2000)]. Scale invariance is a property not about algebraic equations but rather about functional equations, which have as their solutions not numbers but rather functional forms. The key idea of universality is that the identical set of laws hold across diverse markets, and over diverse time periods. This work was carried out in collaboration with a number of students and colleagues, chief among whom are X. Gabaix (MIT and Princeton) and V. Plerou (Boston University).

  9. Interpreting the Climatic Effects on Xylem Functional Traits in Two Mediterranean Oak Species: The Role of Extreme Climatic Events.

    Science.gov (United States)

    Rita, Angelo; Borghetti, Marco; Todaro, Luigi; Saracino, Antonio

    2016-01-01

    In the Mediterranean region, the widely predicted rise in temperature, change in the precipitation pattern, and increase in the frequency of extreme climatic events are expected to alter the shape of ecological communities and to affect plant physiological processes that regulate ecosystem functioning. Although change in the mean values are important, there is increasing evidence that plant distribution, survival, and productivity respond to extremes rather than to the average climatic condition. The present study aims to assess the effects of both mean and extreme climatic conditions on radial growth and functional anatomical traits using long-term tree-ring time series of two co-existing Quercus spp. from a drought-prone site in Southern Italy. In particular, this is the first attempt to apply the Generalized Additive Model for Location, Scale, and Shape (GAMLSS) technique and Bayesian modeling procedures to xylem traits data set, with the aim of (i) detecting non-linear long-term responses to climate and (ii) exploring relationships between climate extreme and xylem traits variability in terms of probability of occurrence. This study demonstrates the usefulness of long-term xylem trait chronologies as records of environmental conditions at annual resolution. Statistical analyses revealed that most of the variability in tree-ring width and specific hydraulic conductivity might be explained by cambial age. Additionally, results highlighted appreciable relationships between xylem traits and climate variability more than tree-ring width, supporting also the evidence that the plant hydraulic traits are closely linked to local climate extremes rather than average climatic conditions. We reported that the probability of extreme departure in specific hydraulic conductivity (Ks) rises at extreme values of Standardized Precipitation Index (SPI). Therefore, changing frequency or intensity of extreme events might overcome the adaptive limits of vascular transport, resulting

  10. Climate-related research in Svalbard

    International Nuclear Information System (INIS)

    The Svalbard archipelago is located in the Norwegian Arctic, 76-81N. In the Kongsfjord area, 79N, on northwest Spitsbergen, there has been increasing research activity in several climate-related disciplines over the last few years. This research will contribute to the global efforts on monitoring and detecting possible global changes. An intensified program monitoring hydrological processes was run from 1974 to 1978 and restarted in 1988. One well-equipped station for atmospheric research is also established. Four major glaciers are being thoroughly investigated, a program which includes mass balance studies, drainage patterns and core analyses. Since 1978 a permafrost station has been operated in Svea, south-central Spitsbergen. The trend in glacier mass balance analyses shows fairly stable negative conditions, the net balance is slightly increasing due to a slight increase in the winter precipitation. There is no sign of climatic warming through increased melting. The temperature data show a very slight cooling during the ablation period. A reconstruction of mass balance data for the Broegger glacier shows that the mass balance has been consistently negative since 1918

  11. Climate Model Simulation of Present and Future Extreme Events in Latin America and the Caribbean: What Spatial Resolution is Required?

    Science.gov (United States)

    Rowe, C. M.; Oglesby, R. J.; Mawalagedara, R.; Mohammad Abadi Kamarei, A.

    2015-12-01

    Latin America and the Caribbean are at risk of extreme climate events, including flooding rains, damaging winds, drought, heat waves, and in high elevation mountainous regions, excessive snowfalls. The causes of these events are numerous - flooding rains and damaging winds are often associated with tropical cyclones, but also can occur, either separately or in tandem, due to smaller, more localized storms. Similarly, heat waves and droughts can be large scale or localized, and frequently occur together (as excessive drying can lead to enhanced heating, while enhanced heating in turn promotes additional drying). Even in the tropics, extreme snow and ice events can have severe consequences due to avalanches, and also impact water resources. Understanding and modeling the climate controls behind these extreme events requires consideration of a range of time and space scales. A common strategy is to use a global climate model (GCM) to simulate the large-scale (~100km) daily atmospheric controls on extreme events. A limited area, high resolution regional climate model (RCM) is then employed to dynamically downscale the results, so as to better incorporate the influence of topography and, secondarily, the nature of the land cover. But what resolution is required to provide the necessary results, i.e., minimize biases due to improper resolution? In conjunction with our partners from participating Latin American and Caribbean nations, we have made an extensive series of simulations, both region-wide and for individual countries, using the WRF regional climate model to downscale output from a variety of GCMs, as well as Reanalyses (as a proxy for observations). The simulations driven by the Reanalyses are used for robust model verification against actual weather station observations. The simulations driven by GCMs are designed to provide projections of future climate, including importantly how the nature and number of extreme events may change through coming decades. Our

  12. Assessing the Impacts of Flooding Caused by Extreme Rainfall Events Through a Combined Geospatial and Numerical Modeling Approach

    Science.gov (United States)

    Santillan, J. R.; Amora, A. M.; Makinano-Santillan, M.; Marqueso, J. T.; Cutamora, L. C.; Serviano, J. L.; Makinano, R. M.

    2016-06-01

    In this paper, we present a combined geospatial and two dimensional (2D) flood modeling approach to assess the impacts of flooding due to extreme rainfall events. We developed and implemented this approach to the Tago River Basin in the province of Surigao del Sur in Mindanao, Philippines, an area which suffered great damage due to flooding caused by Tropical Storms Lingling and Jangmi in the year 2014. The geospatial component of the approach involves extraction of several layers of information such as detailed topography/terrain, man-made features (buildings, roads, bridges) from 1-m spatial resolution LiDAR Digital Surface and Terrain Models (DTM/DSMs), and recent land-cover from Landsat 7 ETM+ and Landsat 8 OLI images. We then used these layers as inputs in developing a Hydrologic Engineering Center Hydrologic Modeling System (HEC HMS)-based hydrologic model, and a hydraulic model based on the 2D module of the latest version of HEC River Analysis System (RAS) to dynamically simulate and map the depth and extent of flooding due to extreme rainfall events. The extreme rainfall events used in the simulation represent 6 hypothetical rainfall events with return periods of 2, 5, 10, 25, 50, and 100 years. For each event, maximum flood depth maps were generated from the simulations, and these maps were further transformed into hazard maps by categorizing the flood depth into low, medium and high hazard levels. Using both the flood hazard maps and the layers of information extracted from remotely-sensed datasets in spatial overlay analysis, we were then able to estimate and assess the impacts of these flooding events to buildings, roads, bridges and landcover. Results of the assessments revealed increase in number of buildings, roads and bridges; and increase in areas of land-cover exposed to various flood hazards as rainfall events become more extreme. The wealth of information generated from the flood impact assessment using the approach can be very useful to the

  13. Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveys

    CERN Document Server

    Chung, Sun-Ju; Koo, Jae-Rim

    2014-01-01

    Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over the peak, confident planet detection did not happen due to extremely weak central perturbations (fractional deviations of $\\lesssim 2\\%$). For confident detection of planets in extremely weak central perturbation (EWCP) events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems.The next-generation ground-based observation project, KMTNet (Korea Microlensing Telescope Network), satisfies the conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of $\\leq 2\\%$ in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of $> 50\\%$ in the case of $\\lesssim 100\\ M_{\\rm E}$ planets with separations of $0.2\\ {\\rm AU} \\lesssim d \\lesssim 20\\ {\\rm AU}$. We find that for m...

  14. The role of Natural Flood Management in managing floods in large scale basins during extreme events

    Science.gov (United States)

    Quinn, Paul; Owen, Gareth; ODonnell, Greg; Nicholson, Alex; Hetherington, David

    2016-04-01

    There is a strong evidence database showing the negative impacts of land use intensification and soil degradation in NW European river basins on hydrological response and to flood impact downstream. However, the ability to target zones of high runoff production and the extent to which we can manage flood risk using nature-based flood management solution are less known. A move to planting more trees and having less intense farmed landscapes is part of natural flood management (NFM) solutions and these methods suggest that flood risk can be managed in alternative and more holistic ways. So what local NFM management methods should be used, where in large scale basin should they be deployed and how does flow is propagate to any point downstream? Generally, how much intervention is needed and will it compromise food production systems? If we are observing record levels of rainfall and flow, for example during Storm Desmond in Dec 2015 in the North West of England, what other flood management options are really needed to complement our traditional defences in large basins for the future? In this paper we will show examples of NFM interventions in the UK that have impacted at local scale sites. We will demonstrate the impact of interventions at local, sub-catchment (meso-scale) and finally at the large scale. These tools include observations, process based models and more generalised Flood Impact Models. Issues of synchronisation and the design level of protection will be debated. By reworking observed rainfall and discharge (runoff) for observed extreme events in the River Eden and River Tyne, during Storm Desmond, we will show how much flood protection is needed in large scale basins. The research will thus pose a number of key questions as to how floods may have to be managed in large scale basins in the future. We will seek to support a method of catchment systems engineering that holds water back across the whole landscape as a major opportunity to management water

  15. Genetic Programming for the Downscaling of Extreme Rainfall Events on the East Coast of Peninsular Malaysia

    OpenAIRE

    Sahar Hadi Pour; Sobri Bin Harun; Shamsuddin Shahid

    2014-01-01

    A genetic programming (GP)-based logistic regression method is proposed in the present study for the downscaling of extreme rainfall indices on the east coast of Peninsular Malaysia, which is considered one of the zones in Malaysia most vulnerable to climate change. A National Centre for Environmental Prediction reanalysis dataset at 42 grid points surrounding the study area was used to select the predictors. GP models were developed for the downscaling of three extreme rainfall indices: day...

  16. Considerations on the influence of extreme events on the phosphorus transport from river catchments to the sea.

    Science.gov (United States)

    Zessner, M; Postolache, C; Clement, A; Kovacs, A; Strauss, P

    2005-01-01

    In this paper, results from rivers of different sizes in Romania, Hungary and Austria are presented. The paper shows the dynamics of extreme events and their contribution to the total P and suspended solids transported in these rivers. Special attention is paid to the influence of the size of the catchment and the event probability on the relative contribution of a single event to the total loads transported in the river. Further, the development of phosphorus loads along the Danube River at a flood event is shown. From the results it can be concluded that there is no immediate influence of high flow and flood events in upstream parts of the Basin on the transport of phosphorus from the catchment to the receiving Sea. Particle-bound phosphorus is mobilised from the catchment (through erosion) and the river bottom to a high extent at high flow events and transported at peak discharges to downstream, where retention by sedimentation of particles takes place. On the one hand this retention is a transport to flooded areas. In this case it can be considered as more or less long term retention. On the other hand sedimentation takes place in the riverbed, in case the tractive effort of the river is reduced. In this second case the P-pool in the sediments of the sedimentation area will be increased. If anaerobic conditions in the sediment appear, part of the phosphorus will be transformed to soluble ortho-phosphate and will continuously contribute to the phosphorus transport to the receiving sea. Part of the P-retained in the river sediment will be mobilised by resuspension at the next biggest high flow event. Altogether, these alternating processes of suspension, transport, export to flooded areas or sedimentation in the river bed with partly solution and partly resuspension at the next event decrease the share of the phosphorus transport during high flow events on the total loads transported in the more downstream parts of a catchments as compared to the more upstream

  17. To what extent does variability of historical rainfall series influence extreme event statistics of sewer system surcharge and overflows?

    DEFF Research Database (Denmark)

    Schaarup-Jensen, Kjeld; Rasmussen, Michael R.; Thorndahl, Søren

    2008-01-01

    volumes. Traditionally it is rarely to dispose of long term rainfall time series from a local catchment rain gauge. In the present case study this is actually the case. 2 rainfall gauges have recorded events for approximately 9 years at 2 locations within the catchment. Beside these 2 gauges another 7...... gauges are located at a distance of max 20 kilometers from the catchment. All gauges are included in the Danish national rain gauge system which was launched in 1976. The paper describes to what extent the extreme events statistics based on these 9 series diverge from each other and how this diversity...

  18. To what extent does variability of historical rainfall series influence extreme event statistics of sewer system surcharge and overflows?

    DEFF Research Database (Denmark)

    Schaarup-Jensen, Kjeld; Rasmussen, Michael R.; Thorndahl, Søren

    2009-01-01

    volumes. Traditionally it is rarely to dispose of long term rainfall time series from a local catchment rain gauge. In the present case study this is actually the case. 2 rainfall gauges have recorded events for approximately 9 years at 2 locations within the catchment. Beside these 2 gauges another 7...... gauges are located at a distance of max 20 kilometers from the catchment. All gauges are included in the Danish national rain gauge system which was launched in 1976. The paper describes to what extent the extreme events statistics based on these 9 series diverge from each other and how this diversity...

  19. Extreme climate events,migration for cultivation and policies:A case study in the early Qing Dynasty of China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the historical records of the annual increase in the workforce (men older than 16 years of age), the annual new taxed cropland in the Shengjing area (Northeast China), the extreme climate events in North China, and related management policies in Northeast China during 1661―1680, a case study has been conducted to investigate the relationship between the extreme climate events in North China and the migration to Northeast China for cultivation. This study has found that the migration to Northeast China for cultivation from 1661 to 1680 was a response to the drought events that occurred in North China. The upsurge of migration, which occurred in 1665―1680, was a response to the drought period during 1664―1680 in North China while the fewer disasters period in Northeast China. There were three migratory peaks during the upsurge of migration, which corresponded to the three drought events. The peaks of migration, however, often lagged behind the drought events about 1―2 years. The encourag-ing-migration policy, which was adopted to encourage cultivation in Northeast China, did not produce much migration into the region in the early Qing Dynasty. It did, however, provide a policy background, which ensured more than 10000 migrants per year to Northeast China when North China suffered from drought/flood disasters. As a response to the highest peak of migration induced by the severe droughts in North China during 1664―1667, a prohibiting-migration policy restricted further migration to Northeast China was carried out in 1668. Although the prohibiting-migration policy could not entirely stop the migrants fleeing from famine in North China to Northeast China, the migrants and cultivation were significantly reduced under the policy. The frequent changes of the policy on the years when taxation started after the land was cultivated were also related to climate events. The extreme climate events in North China, migration to Northeast China for cultivation

  20. Extreme climate events, migration for cultivation and policies: A case study in the early Qing Dynasty of China

    Institute of Scientific and Technical Information of China (English)

    FANG XiuQi; YE Yu; ZENG ZaoZao

    2007-01-01

    Based on the historical records of the annual increase in the workforce(men older than 16 years of age),the annual new taxed cropland in the Shengjing area (Northeast China),the extreme climate events in North China,and related management policies in Northeast China during 1661-1680,a case study has been conducted to investigate the relationship between the extreme climate events in North China and the migration to Northeast China for cultivation.This study has found that the migration to Northeast China for cultivation from 1661 to 1680 was a response to the drought events that occurred in North China.The upsurge of migration,which occurred in 1665-1680,was a response to the drought period during 1664-1680 in North China while the fewer disasters period in Northeast China.There were three migratory peaks during the upsurge of migration,which corresponded to the three drought events.The peaks of migration,however,often lagged behind the drought events about 1-2 years.The encouraging-migration policy,which was adopted to encourage cultivation in Northeast China,did not produce much migration into the region in the early Qing Dynasty.It did,however,provide a policy background,which ensured more than 10000 migrants per year to Northeast China when North China suffered from drought/flood disasters.As a response to the highest peak of migration induced by the severe droughts in North China during 1664-1667,a prohibiting-migration policy restricted further migration to Northeast China was carried out in 1668.Although the prohibiting-migration policy could not entirely stop the migrants fleeing from famine in North China to Northeast China,the migrants and cultivation were significantly reduced under the policy.The frequent changes of the policy on the years when taxation started after the land was cultivated were also related to climate events.The extreme climate events in North China,migration to Northeast China for cultivation,and the related management policies showed

  1. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard

    Science.gov (United States)

    Semenchuk, Philipp R; Elberling, Bo; Cooper, Elisabeth J

    2013-01-01

    Abstract The High Arctic winter is expected to be altered through ongoing and future climate change. Winter precipitation and snow depth are projected to increase and melt out dates change accordingly. Also, snow cover and depth will play an important role in protecting plant canopy from increasingly more frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5 years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas octopetala. However, the affected species were resilient and individuals did not experience any long term effects. In the case of short or cold summers, a subset of species suffered reduced reproductive success, which may affect future plant composition through possible cascading competition effects. Extreme winter warming events were shown to expose the canopy to cold winter air. The following summer most of the overwintering flower buds could not produce flowers. Thus reproductive success is reduced if this occurs in subsequent years. We conclude that snow depth influences flower abundance by altering season length and by protecting or exposing flower buds to cold winter air, but most species studied are resistant to changes. Winter warming events, often

  2. Communicating and managing change during extreme weather events: promising practices for responding to urgent and emergent climate threats.

    Science.gov (United States)

    Tinker, Tim L

    2013-01-01

    Large-scale weather events in the USA such as hurricanes Sandy, Isaac and Katrina challenge traditional approaches to change communication and management (CCM) before during and after crises. A major challenge (as well as opportunity) is addressing change from the 'whole-community' perspective affecting a spectrum of people, policies, processes, behaviours and outcomes. When CCM is used effectively, one of its fundamental advantages is creating a sense of urgency. This paper looks at optimising communication during extreme weather events, engaging stakeholders, harnessing the power of social media and change, and correlating organisational and individual behaviours and actions. The strategic blend of change management and crisis communication strategies and tactics in CCM is a central feature in the response to the full range of extreme weather scenarios. PMID:23835423

  3. Projecting future climate change effects on the extreme hydrological drought events in the Weihe River basin, China

    OpenAIRE

    Yuan, F.; San, Y. Y.; Li, Y.; Ma, M.; Ren, L.; Zhao, C; Liu, Y; Yang, X.; Jiang, S.; H Shen

    2015-01-01

    In this study, a framework to project the potential future climate change impacts on extreme hydrological drought events in the Weihe River basin in North China is presented. This framework includes a large-scale hydrological model driven by climate outputs from a regional climate model for historical streamflow simulations and future streamflow projections, and models for univariate drought assessment and copula-based bivariate drought analysis. It is projected by the univa...

  4. Managing Expectations: Results from Case Studies of US Water Utilities on Preparing for, Coping with, and Adapting to Extreme Events

    Science.gov (United States)

    Beller-Simms, N.; Metchis, K.

    2014-12-01

    Water utilities, reeling from increased impacts of successive extreme events such as floods, droughts, and derechos, are taking a more proactive role in preparing for future incursions. A recent study by Federal and water foundation investigators, reveals how six US water utilities and their regions prepared for, responded to, and coped with recent extreme weather and climate events and the lessons they are using to plan future adaptation and resilience activities. Two case studies will be highlighted. (1) Sonoma County, CA, has had alternating floods and severe droughts. In 2009, this area, home to competing water users, namely, agricultural crops, wineries, tourism, and fisheries faced a three-year drought, accompanied at the end by intense frosts. Competing uses of water threatened the grape harvest, endangered the fish industry and resulted in a series of regulations, and court cases. Five years later, new efforts by partners in the entire watershed have identified mutual opportunities for increased basin sustainability in the face of a changing climate. (2) Washington DC had a derecho in late June 2012, which curtailed water, communications, and power delivery during a record heat spell that impacted hundreds of thousands of residents and lasted over the height of the tourist-intensive July 4th holiday. Lessons from this event were applied three months later in anticipation of an approaching Superstorm Sandy. This study will help other communities in improving their resiliency in the face of future climate extremes. For example, this study revealed that (1) communities are planning with multiple types and occurrences of extreme events which are becoming more severe and frequent and are impacting communities that are expanding into more vulnerable areas and (2) decisions by one sector can not be made in a vacuum and require the scientific, sectoral and citizen communities to work towards sustainable solutions.

  5. A comparison of regional approaches to the frequency analysis of extreme precipitation events in Slovakia and Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Gaál, L.; Kyselý, Jan

    Helsinki: Finish Environment Institute, 2007 - (Heinonen, M.), s. 133-139 ISBN 978-952-11-2790-8. [International Conference on Climate and Water /3./. Helsinki (FI), 03.09.2007-06.09.2007] R&D Projects: GA AV ČR KJB300420601 Institutional research plan: CEZ:AV0Z30420517 Keywords : regional frequency analysis * region-of-influence approach * pooling groups * extreme 5-day precipitation events Subject RIV: DG - Athmosphere Sciences, Meteorology

  6. The first annually-resolved lake record of extreme precipitation events since AD 1374 in NE Iberian Peninsula

    Science.gov (United States)

    Corella, Juan Pablo; Benito, Gerardo; Rodríguez-Lloveras, Xavier; Brauer, Achim; Valero-Garcés, Blas L.

    2014-05-01

    Lake Montcortès is a small (0.14 km2 surface area), 30 m deep, karstic lake located in the eastern Pre-Pyrenees (NE Spain). The permanent anoxic hypolimnetic conditions in this lake have favored the preservation of finely annually laminated sediments in central-distal areas of the lake basin for the last three millennia. A robust age model has been established through varve counting on petrographic thin sections combined with radiocarbon and 210Pb dating. The good correlation of the varve counting with the 14C AMS dates underlines the annual nature of the lamination. Three main types of detrital microfacies have been distinguished in the varves: i) non-continuous detrital layers; ii) continuous detrital layers; iii) matrix-supported layers. In addition, two types of turbidite layers have been identified. Transport mechanisms have been proposed for those deposits including slope reworking processes as well as interflow and underflow events. Annual number of detrital layers interbedded within this varve record was compared against instrumental records of extreme daily rainfalls (available since 1917) providing minimum rainfall thresholds and return periods associated to the identified types of clastic microfacies. Non-continuous detrital layers are deposited during rainfall events higher than 80 mm (> 2 years in average recurrence interval) while graded detrital layers and turbidites were associated with even higher amplitude rainfall events (> 90mm and > 4 years recurrence interval). The frequency distribution of extreme hydro-meteorological events during the last centuries is not stationary and its pattern coincides with historical floods from the nearby Segre River. Higher heavy rainfall frequency occurred during AD 1347-1400 and AD 1844-1894, while less rainfall events happened at AD 1441-1508, 1547-1592, 1656-1712, 1765-1822 and 1917-2012. Variations in extreme rainfall frequencies prior to the 20th century show a positive correlation with solar activity

  7. Precipitation trends over the Korean peninsula: typhoon-induced changes and a typology for characterizing climate-related risk

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong-Suk [School of Energy and Environment, City University of Hong Kong, Hong Kong, People' s Republic of China (China); Jain, Shaleen, E-mail: shaleen.jain@maine.edu [Department of Civil and Environmental Engineering, University of Maine, Orono, ME 04469-5711 (United States)

    2011-07-15

    Typhoons originating in the west Pacific are major contributors to climate-related risk over the Korean peninsula. The current perspective regarding improved characterization of climatic risk and the projected increases in the intensity, frequency, duration, and power dissipation of typhoons during the 21st century in the western North Pacific region motivated a reappraisal of historical trends in precipitation. In this study, trends in the magnitude and frequency of seasonal precipitation in the five major river basins in Korea are analyzed on the basis of a separation analysis, with recognition of moisture sources (typhoon and non-typhoon). Over the 1966-2007 period, typhoons accounted for 21-26% of seasonal precipitation, with the largest values in the Nakdong River Basin. Typhoon-related precipitation events have increased significantly over portions of Han, Nakdong, and Geum River Basins. Alongside broad patterns toward increases in the magnitude and frequency of precipitation, distinct patterns of trends in the upper and lower quartiles (corresponding to changes in extreme events) are evident. A trend typology-spatially resolved characterization of the combination of shifts in the upper and lower tails of the precipitation distribution-shows that a number of sub-basins have undergone significant changes in one or both of the tails of the precipitation distribution. This broader characterization of trends illuminates the relative role of causal climatic factors and an identification of 'hot spots' likely to experience high exposure to typhoon-related climatic extremes in the future.

  8. Precipitation trends over the Korean peninsula: typhoon-induced changes and a typology for characterizing climate-related risk

    International Nuclear Information System (INIS)

    Typhoons originating in the west Pacific are major contributors to climate-related risk over the Korean peninsula. The current perspective regarding improved characterization of climatic risk and the projected increases in the intensity, frequency, duration, and power dissipation of typhoons during the 21st century in the western North Pacific region motivated a reappraisal of historical trends in precipitation. In this study, trends in the magnitude and frequency of seasonal precipitation in the five major river basins in Korea are analyzed on the basis of a separation analysis, with recognition of moisture sources (typhoon and non-typhoon). Over the 1966-2007 period, typhoons accounted for 21-26% of seasonal precipitation, with the largest values in the Nakdong River Basin. Typhoon-related precipitation events have increased significantly over portions of Han, Nakdong, and Geum River Basins. Alongside broad patterns toward increases in the magnitude and frequency of precipitation, distinct patterns of trends in the upper and lower quartiles (corresponding to changes in extreme events) are evident. A trend typology-spatially resolved characterization of the combination of shifts in the upper and lower tails of the precipitation distribution-shows that a number of sub-basins have undergone significant changes in one or both of the tails of the precipitation distribution. This broader characterization of trends illuminates the relative role of causal climatic factors and an identification of 'hot spots' likely to experience high exposure to typhoon-related climatic extremes in the future.

  9. Insurance as an adaptation strategy for extreme weather events indeveloping countries and economies in transition

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Evan

    2004-06-30

    thisperiod, insurance covered four percent of total costs of weather-relateddisasters in emerging markets compared to 40 percent in high-incomecountries. While relatively small, insurance payments to people inemerging markets associated with these losses were three-times themagnitude of international aid. The potential for changes in weatherpatterns, including both average conditions and extreme events, wouldlikely raise the demand for insurance whether the changes area resultnatural variability or human-induced climate change. At the same time,increases in weather-related damage create uncertainties and challengeinsurers ability and willingness to assume or affordably price these newrisks. Sustainable development can contribute to managing and maintainingthe insurability of these risks and thereby reduce the need forindividuals and governments to absorb the costs.Because of themulti-national structure of the insurance a

  10. Trend of extreme precipitation events over China in last 40 years

    International Nuclear Information System (INIS)

    Using the daily precipitation data of 740 stations in China from 1960 to 2000, the analysis on the variations and distributions of the frequency and the percentage of extreme precipitation to the annual rainfall have been performed in this paper. Results indicate that the percentage of heavy rains (above 25mm/day) in the annual rainfall has increased, while on average the day number of heavy rains has slightly reduced during the past 40 years. In the end of 1970s and the beginning of 1980s, both the number of days with extreme precipitation and the percentage of extreme precipitation abruptly changed over China, especially in the northern China. By moving t test, the abrupt change year of extreme precipitation for each station and its spatial distribution over the whole country are also obtained. The abrupt change years concentrated in 1978–1982 for most regions of northern China while occurred at various stations in southern China in greatly different/diverse years. Besides the abrupt change years of extreme precipitation at part stations of Northwest China happened about 5 years later in comparison with that of the country's average

  11. Multi-Scale Statistical Evaluation of CMIP5 Predictions of Extreme Precipitation Events

    Science.gov (United States)

    Allen, M. R.; Fu, J. S.; Gao, Y.; Drake, J.; Lamarque, J.

    2012-12-01

    In view of risk to critical infrastructure, many decision makers are concerned about extreme precipitation potential at specific locations; yet modeling of precipitation at local, regional and global scale remains uncertain and in many regions, problematic. We examine both physical and statistical strategies for improvement in predictions at global and regional scale. Various probability distribution functions are fit to extreme precipitation data such as National Climatic Data Center (NCDC) observational data, National Aeronautics and Space Administration (NASA) satellite observations and location-specific point gauge measurements in order to determine which statistical method gives the best predictive values for past observed extremes for a given location at various resolutions. While the Log Pearson III distribution shows better return-time extreme precipitation predictive capability than the Gumbel, or Type I Extreme Value Distribution for specific locations at coarse resolution (2x2.5 degree), physically-based regionally- and seasonally-informed methods incorporating both time and space parameters may better suit local and short term intensity predictions. Methods applied to Coupled Model Intercomparison Project Phase 5 (CMIP5) climate model historical data determine model capability to capture not only precipitation averages or maxima but also multi-decadal probability distributions. Uncertainty quantification of global and dynamically-downscaled Representative Concentration Pathway (RCP) 4.5 and 8.5 scenario outputs derived from these methods serve accordingly to determine regional and local risk predictions associated with climate change.

  12. Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveys

    International Nuclear Information System (INIS)

    Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over its peak, confident planet detection did not happen due to extremely weak central perturbations (EWCPs, fractional deviations of ≲ 2%). For confident detection of planets in EWCP events, it is necessary to have both high cadence monitoring and high photometric accuracy better than those of current follow-up observation systems. The next-generation ground-based observation project, Korea Microlensing Telescope Network (KMTNet), satisfies these conditions. We estimate the probability of occurrence of EWCP events with fractional deviations of ≤2% in high-magnification events and the efficiency of detecting planets in the EWCP events using the KMTNet. From this study, we find that the EWCP events occur with a frequency of >50% in the case of ≲ 100 M E planets with separations of 0.2 AU ≲ d ≲ 20 AU. We find that for main-sequence and sub-giant source stars, ≳ 1 M E planets in EWCP events with deviations ≤2% can be detected with frequency >50% in a certain range that changes with the planet mass. However, it is difficult to detect planets in EWCP events of bright stars like giant stars because it is easy for KMTNet to be saturated around the peak of the events because of its constant exposure time. EWCP events are caused by close, intermediate, and wide planetary systems with low-mass planets and close and wide planetary systems with massive planets. Therefore, we expect that a much greater variety of planetary systems than those already detected, which are mostly intermediate planetary systems, regardless of the planet mass, will be significantly detected in the near future.

  13. Comparison of pointwise and regional statistical approaches to detect non stationarity in extreme rainfall events. Application to the Sahelian region

    Science.gov (United States)

    Panthou, G.; Vischel, T.; Lebel, T.; Quantin, G.; Favre, A.; Blanchet, J.; Ali, A.

    2012-12-01

    Studying trends in rainfall extremes at regional scale is required to provide reference climatology to evaluate General Circulation Model global predictions as well as to help managing and designing hydraulic works. The present study compares three methods to detect trends (linear and change-point) in series of daily rainfall annual maxima: (i) The first approach is widely used and consist in applying statistical stationarity tests (linear trend and change-point) on the point-wise maxima series; (ii) The second approach compares the performances of a constant and a time dependent Generalized Extreme Value (GEV) distribution fitted to the point-wise maxima series. (iii) The last method uses an original regional statistical model based on space-time GEV distribution which is used to detect changes in rainfall extremes directly at regional scale. The three methods are applied to detect trends in extreme daily rainfall over the Sahel during the period 1950-1990 for which a network of 128 daily rain gages is available. This region has experienced an intense drought since the end of the 1960s; it is thus an interesting case-study to illustrate how a regional climate change can affect the extreme rainfall distributions. One major result is that the statistical stationarity tests rarely detect non-stationarities in the series while the two GEV-based models converge to show that the extreme rainfall series have a negative break point around 1970. The study points out the limit of the widely used classical stationarity tests to detect trends in noisy series affected by sampling errors. The use of parametric time-dependent GEV seems to reduce this effect especially when a regional approach is used. From a climatological point of view, the results show that the great Sahelian drought has been accompanied by a decrease of extreme rainfall events, both in magnitude and occurence.

  14. Possible effect of extreme solar energetic particle events of September–October 1989 on polar stratospheric aerosols: a case study

    Directory of Open Access Journals (Sweden)

    I. A. Mironova

    2013-09-01

    Full Text Available The main ionization source of the middle and low Earth's atmosphere is related to energetic particles coming from outer space. Usually it is ionization from cosmic rays that is always present in the atmosphere. But in a case of a very strong solar eruption, some solar energetic particles (SEPs can reach middle/low atmosphere increasing the ionization rate up to some orders of magnitude at polar latitudes. We continue investigating such a special class of solar events and their possible applications for natural variations of the aerosol content. After the case study of the extreme SEP event of January 2005 and its possible effect upon polar stratospheric aerosols, here we analyze atmospheric applications of the sequence of several events that took place over autumn 1989. Using aerosol data obtained over polar regions from two satellites with space-borne optical instruments SAGE II and SAM II that were operating during September–October 1989, we found that an extreme major SEP event might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, the effect of the additional ambient air ionization on the aerosol formation is minor, in comparison with temperature effect, and can take place only in the cold polar atmospheric conditions. The extra aerosol mass formed under the temperature effect allows attributing most of the changes to the "ion–aerosol clear sky mechanism".

  15. Risk Management in the Original Extreme Sporting Event: The Pole Vault

    Science.gov (United States)

    Bemiller, Jim; Hardin, Robin

    2010-01-01

    The pole vault was considered the ultimate test of physical ability and daring before the advent of modern extreme sports such as skateboarding, snowboarding, and mountain biking. The inherent risks of the pole vault have been well documented. The National Center for Catastrophic Sport Injury Research reported in 2007 that the catastrophic injury…

  16. Numerical simulation of runoff from extreme rainfall events in a mountain water catchment

    Directory of Open Access Journals (Sweden)

    J. Burguete

    2002-01-01

    Full Text Available A numerical model for unsteady shallow water flow over initially dry areas is applied to a case study in a small drainage area at the Spanish Ebro River basin. Several flood mitigation measures (reforestation, construction of a small reservoir and channelization are simulated in the model in order to compare different extreme rainfall-runoff scenarios.

  17. Lower extremity injury criteria for evaluating military vehicle occupant injury in underbelly blast events.

    Science.gov (United States)

    McKay, Brian J; Bir, Cynthia A

    2009-11-01

    Anti-vehicular (AV) landmines and improvised explosive devices (IED) have accounted for more than half of the United States military hostile casualties and wounded in Operation Iraqi Freedom (OIF) (Department of Defense Personnel & Procurement Statistics, 2009). The lower extremity is the predominantly injured body region following an AV mine or IED blast accounting for 26 percent of all combat injuries in OIF (Owens et al., 2007). Detonations occurring under the vehicle transmit high amplitude and short duration axial loads onto the foot-ankle-tibia region of the occupant causing injuries to the lower leg. The current effort was initiated to develop lower extremity injury criteria for occupants involved in underbelly blast impacts. Eighteen lower extremity post mortem human specimens (PMHS) were instrumented with an implantable load cell and strain gages and impacted at one of three incrementally severe AV axial loading conditions. Twelve of the 18 PMHS specimens sustained fractures of the calcaneus, talus, fibula and/or tibia. The initiation of skeletal injury was precisely detected by strain gages and corresponded with local peak axial tibia force. Survival analysis identified peak axial tibia force and impactor velocity as the two best predictors of incapacitating injury. A tibia axial force of 5,931 N and impactor velocity of 10.8 m/s corresponds with a 50 percent risk of an incapacitating injury. The criteria may be utilized to predict the probability of lower extremity incapacitating injury in underbelly blast impacts. PMID:20058557

  18. Probing Collective Effects in Hadronisation with the Extremes of the Underlying Event

    CERN Document Server

    Martin, Tim; Farrington, Sinead

    2016-01-01

    We define a new set of observables to probe the structure of the underlying event in hadron collisions. We use the conventional definition of the `transverse region' in jet events and, for a fixed window in jet $p_\\perp$, propose to measure several discriminating quantities as a function of the level of activity in the transverse region. The measurement of these observables in LHC data would reveal whether, e.g., the properties of `low-UE' events are compatible with equivalent measurements in $e^+e^-$ collisions (jet universality), and whether the scaling behaviour towards `high-UE' events exhibits properties of non-trivial soft-QCD dynamics, such as colour re-connections or other collective phenomena. We illustrate at $\\sqrt{s} = 13$ TeV that significant discriminatory power is obtained in comparisons between MC models with varying treatments of collective effects, including Pythia 8, EPOS, and Dipsy.

  19. Climate Change Risks – Methodological Framework and Case Study of Damages from Extreme Events in Cambodia

    DEFF Research Database (Denmark)

    Halsnæs, Kirsten; Kaspersen, Per Skougaard; Trærup, Sara Lærke Meltofte

    2016-01-01

    Climate change imposes some special risks on Least Developed Countries, and the chapter presents a methodological framework, which can be used to assess the impacts of key assumptions related to damage costs, risks and equity implications on current and future generations. The methodological...... framework is applied to a case study of severe storms in Cambodia based on statistical information on past storm events including information about buildings damaged and victims. Despite there is limited data available on the probability of severe storm events under climate change as well on the actual...... damage costs associated with the events in the case of Cambodia, we are using the past storm events as proxy data in a sensitivity analysis. It is here demonstrated how key assumptions on future climate change, income levels of victims, and income distribution over time, reflected in discount rates...

  20. The Response of Different Audiences to Place-based Communication about the Role of Climate Change in Extreme Weather Events

    Science.gov (United States)

    Halperin, A.; Walton, P.

    2015-12-01

    As the science of extreme event attribution grows, there is an increasing need to understand how the public responds to this type of climate change communication. Extreme event attribution has the unprecedented potential to locate the effects of climate change in the here and now, but there is little information about how different facets of the public might respond to these local framings of climate change. Drawing on theories of place attachment and psychological distance, this paper explores how people with different beliefs and values shift their willingness to mitigate and adapt to climate change in response to local or global communication of climate change impacts. Results will be presented from a recent survey of over 600 Californians who were each presented with one of three experimental conditions: 1) a local framing of the role of climate change in the California drought 2) a global framing of climate change and droughts worldwide, or 3) a control condition of no text. Participants were categorized into groups based on their prior beliefs about climate change according to the Six Americas classification scheme (Leiserowitz et al., 2011). The results from the survey in conjunction with qualitative results from follow-up interviews shed insight into the importance of place in communicating climate change for people in each of the Six Americas. Additional results examine the role of gender and political affiliation in mediating responses to climate change communication. Despite research that advocates unequivocally for local framing of climate change, this study offers a more nuanced perspective of under which circumstances extreme event attribution might be an effective tool for changing behaviors. These results could be useful for scientists who wish to gain a better understanding of how their event attribution research is perceived or for educators who want to target their message to audiences where it could have the most impact.

  1. Extreme rainfall events in karst environments: the case study of September 2014 in the Gargano area (southern Italy)

    Science.gov (United States)

    Martinotti, Maria Elena; Pisano, Luca; Trabace, Maria; Marchesini, Ivan; Peruccacci, Silvia; Rossi, Mauro; Amoruso, Giuseppe; Loiacono, Pierluigi; Vennari, Carmela; Vessia, Giovanna; Parise, Mario; Brunetti, Maria Teresa

    2015-04-01

    In the first week of September 2014, the Gargano Promontory (Apulia, SE Italy) was hit by an extreme rainfall event that caused several landslides, floods and sinkholes. As a consequence of the floods, two people lost their lives and severe socio-economic damages were reported. The highest peaks of rainfall were recorded between September 3rd and 6th at the Cagnano Varano and San Marco in Lamis rain gauges with a maximum daily rainfall (over 230 mm) that is about 30% the mean annual rainfall. The Gargano Promontory is characterized by complex orographic conditions, with the highest elevation of about 1000 m a.s.l. The geological setting consists of different types of carbonate deposits affected by intensive development of karst processes. The morphological and climatic settings of the area, associated with frequent extreme rainfall events can cause various types of geohazards (e.g., landslides, floods, sinkholes). A further element enhancing the natural predisposition of the area to the occurrence of landslides, floods and sinkholes is an intense human activity, characterized by an inappropriate land use and management. In order to obtain consistent and reliable data on the effects produced by the storm, a systematic collection of information through field observations, a critical analysis of newspaper articles and web-news, and a co-operation with the Regional Civil Protection and local geologists started immediately after the event. The information collected has been organized in a database including the location, the occurrence time and the type of geohazard documented with photographs. The September 2014 extreme rainfall event in the Gargano Promontory was also analyzed to validate the forecasts issued by the Italian national early-warning system for rainfall-induced landslides (SANF), developed by the Research Institute for Geo-Hydrological Protection (IRPI) for the Italian national Department for Civil Protection (DPC). SANF compares rainfall measurements and

  2. Extreme fire events are related to previous-year surface moisture conditions in permafrost-underlain larch forests of Siberia

    International Nuclear Information System (INIS)

    Wildfires are a natural and important element in the functioning of boreal forests. However, in some years, fires with extreme spread and severity occur. Such severe fires can degrade the forest, affect human values, emit huge amounts of carbon and aerosols and alter the land surface albedo. Usually, wind, slope and dry air conditions have been recognized as factors determining fire spread. Here we identify surface moisture as an additional important driving factor for the evolution of extreme fire events in the Baikal region. An area of 127 000 km2 burned in this region in 2003, a large part of it in regions underlain by permafrost. Analyses of satellite data for 2002–2009 indicate that previous-summer surface moisture is a better predictor for burned area than precipitation anomalies or fire weather indices for larch forests with continuous permafrost. Our analysis advances the understanding of complex interactions between the atmosphere, vegetation and soil, and how coupled mechanisms can lead to extreme events. These findings emphasize the importance of a mechanistic coupling of soil thermodynamics, hydrology, vegetation functioning, and fire activity in Earth system models for projecting climate change impacts over the next century. (letter)

  3. No evidence of the effect of extreme weather events on annual occurrence of four groups of ectothermic species.

    Directory of Open Access Journals (Sweden)

    Agnieszka H Malinowska

    Full Text Available Weather extremes may have strong effects on biodiversity, as known from theoretical and modelling studies. Predicted negative effects of increased weather variation are found only for a few species, mostly plants and birds in empirical studies. Therefore, we investigated correlations between weather variability and patterns in occupancy, local colonisations and local extinctions (metapopulation metrics across four groups of ectotherms: Odonata, Orthoptera, Lepidoptera, and Reptilia. We analysed data of 134 species on a 1×1 km-grid base, collected in the last 20 years from the Netherlands, combining standardised data and opportunistic data. We applied dynamic site-occupancy models and used the results as input for analyses of (i trends in distribution patterns, (ii the effect of temperature on colonisation and persistence probability, and (iii the effect of years with extreme weather on all the three metapopulation metrics. All groups, except butterflies, showed more positive than negative trends in metapopulation metrics. We did not find evidence that the probability of colonisation or persistence increases with temperature nor that extreme weather events are reflected in higher extinction risks. We could not prove that weather extremes have visible and consistent negative effects on ectothermic species in temperate northern hemisphere. These findings do not confirm the general prediction that increased weather variability imperils biodiversity. We conclude that weather extremes might not be ecologically relevant for the majority of species. Populations might be buffered against weather variation (e.g. by habitat heterogeneity, or other factors might be masking the effects (e.g. availability and quality of habitat. Consequently, we postulate that weather extremes have less, or different, impact in real world metapopulations than theory and models suggest.

  4. On the analysis of an extreme Bora wind event over the northern Adriatic Sea

    Science.gov (United States)

    Colucci, R. R.; Pucillo, A.

    2010-09-01

    On 10th March 2010 a severe Bora wind event affected the Friuli Venezia Giulia region, northeastern Italy, in particular the gulf of Trieste area (northern Adriatic Sea). Such event has been driven by a widespread westward moving cold pool aloft, coming from the Western Asia, that brought an intense potential vorticity anomaly over the western Mediterranean Sea. It determined a deep cyclogenesis involving all the troposphere. The pressure gradient force in the lowest layers forced a northeastern wind to blow with noticeable strength over the gulf of Trieste area and the Karstic region. The mean ground wind velocity has reached values above 27 m/s (about 100 km/h) for several hours, and maximum gusts exceeded 42 m/s (about 150 km/h) over Trieste town. The northeastern sector of the Adriatic Sea is frequently affected by strong Bora events in particular during the winter semester. This is a characteristic local wind mostly influenced by the orography of the Karstic relieves to the east of Trieste town. The target of this work is to assess the climatological relevance of such an event by comparing it with the most representative events of the past. It has been possible thanks to the long term archive of meteorological observations in Trieste site (I.R. Accademia di Commercio e Nautica, Regio Comitato Talassografico Italiano, Ministero dell'Agricoltura e Foreste, Consiglio Nazionale delle Ricerche): we have found out that this is one of the ten strongest Bora event along the 1871-2010 period. Considerations about the trend and frequency of severe Bora events have been proposed.

  5. A systemic approach for managing extreme risk events-dynamic financial analysis

    OpenAIRE

    Ph.D.Student Rodica Ianole; Ph. D. Student Ioana - Julieta Josan; Ph.D.Marian Zulean

    2011-01-01

    Following the Black Swan logic, it often happens that what we do not know becomes more relevant that what we (believe to) know. The management of extreme risks falls under this paradigm in the sense that it cannot be limited to a static approach based only on objective and easily quantifiable variables. Making appeal to the operational tools developed primarily for the insurance industry, the present paper aims to investigate how dynamic financial analysis (DFA) can be used within the framewo...

  6. A hierarchical Bayesian spatio-temporal model for extreme precipitation events

    KAUST Repository

    Ghosh, Souparno

    2011-03-01

    We propose a new approach to model a sequence of spatially distributed time series of extreme values. Unlike common practice, we incorporate spatial dependence directly in the likelihood and allow the temporal component to be captured at the second level of hierarchy. Inferences about the parameters and spatio-temporal predictions are obtained via MCMC technique. The model is fitted to a gridded precipitation data set collected over 99 years across the continental U.S. © 2010 John Wiley & Sons, Ltd..

  7. Association between anomalies of moisture flux and extreme runoff events in the south-eastern Alps

    Czech Academy of Sciences Publication Activity Database

    Müller, Miloslav; Kašpar, Marek

    2011-01-01

    Roč. 11, č. 3 (2011), s. 915-920. ISSN 1561-8633 Grant ostatní: MŠMT(CZ) MSM0021620831 Institutional research plan: CEZ:AV0Z30420517 Keywords : moisture flux * extreme precipitation * seasonality of heavy rains Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.983, year: 2011 http://www.nat-hazards-earth-syst-sci.net/11/915/2011/

  8. The Role of Insurance in Managing Extreme Events: Implications for Terrorism Coverage

    OpenAIRE

    Howard Kunreuther

    2001-01-01

    A key question being raised since September 11 th is the appropriate role of the private and public sectors in reducing losses and offering insurance protection against extreme risks such as natural disasters, technological accidents and terrorist activities. The following scenario illustrates the challenges and opportunities facing the insurance and reinsurance industry in this regard: Scenario: Over the past 10 years the AllRisk (AR) Insurance Company has provided $500 million in coverage t...

  9. Extreme ozone events: Tail behavior of the surface ozone distribution over the U.S.

    Science.gov (United States)

    Phalitnonkiat, Pakawat; Sun, Wenxiu; Grigoriu, Mircea Dan; Hess, Peter; Samorodnitsky, Gennady

    2016-03-01

    The ground level ozone concentration over the continental United States is analyzed from the point of view of modern Extreme Value Theory using ozone data from the Clean Air Status and Trends Network (CASTNET) at 25 measurement sites. At each site the data is analyzed separately for two time periods (1992-2002 and 2003-2013) approximately separated by the NOX SIP call. The Generalized Pareto Distribution is fit to extremes of the ozone concentration by using a combination of maximum likelihood estimates (MLEs) and Hill estimates. The data is appropriately transformed prior to extreme value analysis and data in the right tail is separated from that in the middle part of the distribution. This analysis is compared to current approaches by using synthetic data. Under a variety of conditions the procedure using the MLE approach is likely to underestimate the tail of the distribution. The analysis of the CASTNET ozone data shows that at some locations the ozone probability distribution is not exponentially bounded, and thus can be characterized as heavy tailed, and that at other locations this distribution is not heavy and is bounded to the right so that the ozone concentration is bounded for any return period. The tails of the distribution of ozone concentration become heavier following the NOX SIP call at most of the sites with heavy tails prior to this call.

  10. How did ocean warming affect Australian rainfall extremes during the 2010/2011 La Niña event?

    Science.gov (United States)

    Ummenhofer, Caroline C.; Sen Gupta, Alexander; England, Matthew H.; Taschetto, Andréa. S.; Briggs, Peter R.; Raupach, Michael R.

    2015-11-01

    Extreme rainfall conditions in Australia during the 2010/2011 La Niña resulted in devastating floods claiming 35 lives, causing billions of dollars in damages, and far-reaching impacts on global climate, including a significant drop in global sea level and record terrestrial carbon uptake. Northeast Australian 2010/2011 rainfall was 84% above average, unusual even for a strong La Niña, and soil moisture conditions were unprecedented since 1950. Here we demonstrate that the warmer background state increased the likelihood of the extreme rainfall response. Using atmospheric general circulation model experiments with 2010/2011 ocean conditions with and without long-term warming, we identify the mechanisms that increase the likelihood of extreme rainfall: additional ocean warming enhanced onshore moisture transport onto Australia and ascent and precipitation over the northeast. Our results highlight the role of long-term ocean warming for modifying rain-producing atmospheric circulation conditions, increasing the likelihood of extreme precipitation for Australia during future La Niña events.

  11. Projected changes of extreme weather events in the eastern United States based on a high resolution climate modeling system

    International Nuclear Information System (INIS)

    This study is the first evaluation of dynamical downscaling using the Weather Research and Forecasting (WRF) Model on a 4 km × 4 km high resolution scale in the eastern US driven by the new Community Earth System Model version 1.0 (CESM v1.0). First we examined the global and regional climate model results, and corrected an inconsistency in skin temperature during the downscaling process by modifying the land/sea mask. In comparison with observations, WRF shows statistically significant improvement over CESM in reproducing extreme weather events, with improvement for heat wave frequency estimation as high as 98%. The fossil fuel intensive scenario Representative Concentration Pathway (RCP) 8.5 was used to study a possible future mid-century climate extreme in 2057–9. Both the heat waves and the extreme precipitation in 2057–9 are more severe than the present climate in the Eastern US. The Northeastern US shows large increases in both heat wave intensity (3.05 °C higher) and annual extreme precipitation (107.3 mm more per year). (letter)

  12. Extreme solar event of AD775: Potential radiation exposure to crews in deep space

    Science.gov (United States)

    Townsend, L. W.; Porter, J. A.; deWet, W. C.; Smith, W. J.; McGirl, N. A.; Heilbronn, L. H.; Moussa, H. M.

    2016-06-01

    The existence of a historically large cosmic event in AD774 or 775, of probable solar origin, has recently been confirmed from records of 14C levels in tree rings located at widely separated locations on Earth, 10Be records in polar ice cores, and historical records of aurora sightings. Usoskin et al. (2013) [16] suggest that such an event, of solar origin, would have a proton fluence of ~4.5×1010 cm-2 at energies above 30 MeV, with a hard energy spectrum comparable to the event of 23 February 1956. In this work we investigate the possible radiation exposures to crews of missions on the surface of Mars, from such an event. In this work we use the HZETRN radiation transport code, originally developed at NASA Langley Research Center, and the Computerized Anatomical Male and Female human geometry models to estimate exposures for a variety of aluminum shield areal densities similar to those provided by a spacesuit, surface lander, and permanent habitat on the Martian surface. Comparisons of the predicted organ exposures with recently-recommended radiation exposure limits are made. Potential health effects on crews, of such an event, are also discussed.

  13. Flux characteristics of total dissolved iron and its species during extreme rainfall event in the midstream of the Heilongjiang River.

    Science.gov (United States)

    Guan, Jiunian; Yan, Baixing; Zhu, Hui; Wang, Lixia; Lu, Duian; Cheng, Long

    2015-04-01

    The occurrence of extreme rainfall events and associated flooding has been enhanced due to climate changes, and is thought to influence the flux of total dissolved iron (TDI) in rivers considerably. Since TDI is a controlling factor in primary productivity in marine ecosystems, alteration of riverine TDI input to the ocean may lead to climate change via its effect on biological productivity. During an extreme rainfall event that arose in northeastern China in 2013, water samples were collected in the midstream of the Heilongjiang River to analyze the concentration and species of TDI as well as other basic parameters. The speciation of TDI was surveyed by filtration and ultrafiltration methods. Compared with data monitored from 2007 to 2012, the concentration of TDI increased significantly during this event, with an average concentration of 1.11 mg/L, and the estimated TDI flux reached 1.2×10(5) tons, equaling the average annual TDI flux level. Species analysis revealed that low-molecular-weight complexed iron was the dominant species, and the impulse of TDI flux could probably be attributed to the hydrological connection to riparian wetlands and iron-rich terrestrial runoff. Moreover, dissolved organic matter played a key role in the flux, species and bioavailability of TDI. In addition, there is a possibility that the rising TDI flux could further influence the transport and cycling of nutrients and related ecological processes in the river, estuary coupled with the coastal ecosystems, which merits closer attention in the future. PMID:25872711

  14. Frequency of Extreme Heat Event as a Surrogate Exposure Metric for Examining the Human Health Effects of Climate Change.

    Science.gov (United States)

    Romeo Upperman, Crystal; Parker, Jennifer; Jiang, Chengsheng; He, Xin; Murtugudde, Raghuram; Sapkota, Amir

    2015-01-01

    Epidemiological investigation of the impact of climate change on human health, particularly chronic diseases, is hindered by the lack of exposure metrics that can be used as a marker of climate change that are compatible with health data. Here, we present a surrogate exposure metric created using a 30-year baseline (1960-1989) that allows users to quantify long-term changes in exposure to frequency of extreme heat events with near unabridged spatial coverage in a scale that is compatible with national/state health outcome data. We evaluate the exposure metric by decade, seasonality, area of the country, and its ability to capture long-term changes in weather (climate), including natural climate modes. Our findings show that this generic exposure metric is potentially useful to monitor trends in the frequency of extreme heat events across varying regions because it captures long-term changes; is sensitive to the natural climate modes (ENSO events); responds well to spatial variability, and; is amenable to spatial/temporal aggregation, making it useful for epidemiological studies. PMID:26641244

  15. Defining Population Health Vulnerability Following an Extreme Weather Event in an Urban Pacific Island Environment: Honiara, Solomon Islands.

    Science.gov (United States)

    Natuzzi, Eileen S; Joshua, Cynthia; Shortus, Matthew; Reubin, Reginald; Dalipanda, Tenneth; Ferran, Karen; Aumua, Audrey; Brodine, Stephanie

    2016-08-01

    Extreme weather events are common and increasing in intensity in the southwestern Pacific region. Health impacts from cyclones and tropical storms cause acute injuries and infectious disease outbreaks. Defining population vulnerability to extreme weather events by examining a recent flood in Honiara, Solomon Islands, can help stakeholders and policymakers adapt development to reduce future threats. The acute and subacute health impacts following the April 2014 floods were defined using data obtained from hospitals and clinics, the Ministry of Health and in-country World Health Organization office in Honiara. Geographical information system (GIS) was used to assess morbidity and mortality, and vulnerability of the health system infrastructure and households in Honiara. The April flash floods were responsible for 21 acute deaths, 33 injuries, and a diarrhea outbreak that affected 8,584 people with 10 pediatric deaths. A GIS vulnerability assessment of the location of the health system infrastructure and households relative to rivers and the coastline identified 75% of the health infrastructure and over 29% of Honiara's population as vulnerable to future hydrological events. Honiara, Solomon Islands, is a rapidly growing, highly vulnerable urban Pacific Island environment. Evaluation of the mortality and morbidity from the April 2014 floods as well as the infectious disease outbreaks that followed allows public health specialists and policy makers to understand the health system and populations vulnerability to future shocks. Understanding the negative impacts natural disaster have on people living in urban Pacific environments will help the government as well as development partners in crafting resilient adaptation development. PMID:27091867

  16. Tracking the Moisture Sources of an Extreme Precipitation Event in Shandong, China in July 2007:A Computational Analysis

    Institute of Scientific and Technical Information of China (English)

    张弛; 李琦

    2014-01-01

    This paper utilizes a modified Water Accounting Model (WAM) to track the moisture sources of an extreme precipitation event in Shandong during 18-20 July 2007. It is found that different methods in dealing with the residual of the water budget always produce different results in moisture recycling calculations. In addition, results from the backward tracking without the residual are in complete agreement with those from the forward tracking with the residual, and vice versa, implying a mathematical consistency. We thus analyze and derive the conditions under which the two tracking approaches equate with each other. We applied the backward tracking to the Shandong extreme rainfall case and obtained quantitative estimates of moisture contributions of three selected regions away from the rainfall area. The results indicate that the spatial pattern rather than numerical value of the recycling moisture is more reliable in tracking the moisture sources. The moisture of this Shandong rainfall event comes mostly from the nearby upwind area in Southwest China, which is of the terrestrial origin; while the moisture originating from the neighboring West Pacific contributes little to this event.

  17. Estimating the frequency of extremely energetic solar events, based on solar, stellar, lunar, and terrestrial records

    CERN Document Server

    Schrijver, C J; Baltensperger, U; Cliver, E W; Guedel, M; Hudson, H S; McCracken, K G; Osten, R A; Peter, Th; Soderblom, D R; Usoskin, I G; Wolff, E W

    2012-01-01

    The most powerful explosions on the Sun [...] drive the most severe space-weather storms. Proxy records of flare energies based on SEPs in principle may offer the longest time base to study infrequent large events. We conclude that one suggested proxy, nitrate concentrations in polar ice cores, does not map reliably to SEP events. Concentrations of select radionuclides measured in natural archives may prove useful in extending the time interval of direct observations up to ten millennia, but as their calibration to solar flare fluences depends on multiple poorly known properties and processes, these proxies cannot presently be used to help determine the flare energy frequency distribution. Being thus limited to the use of direct flare observations, we evaluate the probabilities of large-energy solar explosions by combining solar flare observations with an ensemble of stellar flare observations. We conclude that solar flare energies form a relatively smooth distribution from small events to large flares, while...

  18. Characterization and effects of cold fronts in the Colombian Caribbean Coast and their relationship to extreme wave events

    Directory of Open Access Journals (Sweden)

    J. C. Ortiz-Royero

    2013-07-01

    passage of cold fronts during the last 16 yr were identified. Although the Colombian Caribbean has been affected by storms and hurricanes in the past, this research allows us to conclude that, there is a strong relationship between cold fronts and the largest waves in the Colombian Caribbean during the last 16 yr, which have caused damage to coastal infrastructure. We verified that the passage of a cold front corresponded to the most significant extreme wave event of the last two decades in the Colombian Caribbean, which caused the structural collapse of the Puerto Colombia pier, located near the city of Barranquilla, between 5 and 10 March 2009. This information is invaluable when evaluating average and extreme wave regimes for the purpose of informing the design of structures in this region of the Caribbean.

  19. The Spanish tourist sector facing extreme climate events: a case study of domestic tourism in the heat wave of 2003.

    Science.gov (United States)

    Gómez-Martín, M Belén; Armesto-López, Xosé A; Martínez-Ibarra, Emilio

    2014-07-01

    This research explores, by means of a questionnaire-based survey, public knowledge and perception as well as the behaviour of young Spanish tourists before, during and after the summer holiday period affected by an episode of extreme heat in 2003. The survey was administered between November and December 2004. The extraordinary heat wave of the summer of 2003 can be seen as an example of a normal episode in terms of the predicted intensity and duration of European summers towards the end of the twenty-first century. It can therefore be used as the laboratory setting for this study. In this context, the use of the climate analogue approach allows us to obtain novel perspectives regarding the future impact that this type of event could have on tourist demand, based on a real experience. Likewise, such an approach allows the strategies of adaptation implemented by the different elements in the tourist system in order to cope with the atmospheric episode to be evaluated. Such strategies could prove useful in reducing vulnerability when faced with similar episodes in the future. The main results indicate that Spanish tourists (young segment market) are flexible in adapting to episodes of extremely high temperatures. Their personal perception of the phenomenon, their behaviour and the adaptation measures implemented to a greater or lesser extent before that time, reduce the vulnerability of the sector when faced with this type of event, at least from the point of view of this young segment of the internal national market. In Spain, the episode of extreme heat of 2003 has led to the implementation or improvement of some adaptive measures after the event, especially in the fields of management, policy and education. PMID:23619577

  20. The Spanish tourist sector facing extreme climate events: a case study of domestic tourism in the heat wave of 2003

    Science.gov (United States)

    Gómez-Martín, M. Belén; Armesto-López, Xosé A.; Martínez-Ibarra, Emilio

    2014-07-01

    This research explores, by means of a questionnaire-based survey, public knowledge and perception as well as the behaviour of young Spanish tourists before, during and after the summer holiday period affected by an episode of extreme heat in 2003. The survey was administered between November and December 2004. The extraordinary heat wave of the summer of 2003 can be seen as an example of a normal episode in terms of the predicted intensity and duration of European summers towards the end of the twenty-first century. It can therefore be used as the laboratory setting for this study. In this context, the use of the climate analogue approach allows us to obtain novel perspectives regarding the future impact that this type of event could have on tourist demand, based on a real experience. Likewise, such an approach allows the strategies of adaptation implemented by the different elements in the tourist system in order to cope with the atmospheric episode to be evaluated. Such strategies could prove useful in reducing vulnerability when faced with similar episodes in the future. The main results indicate that Spanish tourists (young segment market) are flexible in adapting to episodes of extremely high temperatures. Their personal perception of the phenomenon, their behaviour and the adaptation measures implemented to a greater or lesser extent before that time, reduce the vulnerability of the sector when faced with this type of event, at least from the point of view of this young segment of the internal national market. In Spain, the episode of extreme heat of 2003 has led to the implementation or improvement of some adaptive measures after the event, especially in the fields of management, policy and education.

  1. Fast-track extreme event attribution: How fast can we disentangle thermodynamic (forced) and dynamic (internal) contributions?

    Science.gov (United States)

    Haustein, Karsten; Otto, Friederike; Uhe, Peter; Allen, Myles; Cullen, Heidi

    2016-04-01

    Within the last decade, extreme weather event attribution has emerged as a new field of science and garnered increasing attention from the wider scientific community and the public. Numerous methods have been put forward to determine the contribution of anthropogenic climate change to individual extreme weather events. So far nearly all such analyses were done months after an event has happened. First, we present our newly established method which can assess the fraction of attributable risk (FAR) of a severe weather event due to an external driver in real-time. The method builds on a large ensemble of atmosphere-only GCM/RCM simulations forced by seasonal forecast sea surface temperatures (SSTs). Taking the UK 2013/14 winter floods as an example, we demonstrate that the change in risk for heavy rainfall during the England floods due to anthropogenic climate change is of similar magnitude using either observed or seasonal forecast SSTs. While FAR is assumed to be independent from event-specific dynamic contributions due to anomalous circulation patterns as a first approximation, the risk of an event to occur under current conditions is clearly a function of the state of the atmosphere. The shorter the event, the more it is a result of chaotic internal weather variability. Hence we are interested to (1) attribute the event to thermodynamic and dynamic causes and to (2) establish a sensible time-scale for which we can make a useful and potentially robust attribution statement with regard to event-specific dynamics. Having tested the dynamic response of our model to SST conditions in January 2014, we find that observed SSTs are required to establish a discernible link between anomalous ocean temperatures and the atmospheric circulation over the North Atlantic in general and the UK in particular. However, for extreme events occurring under strongly anomalous SST patterns, associated with known low-frequency climate modes such as El Nino or La Nina, forecast SSTs can

  2. Extreme violation of sleep hygiene: sleeping against the biological clock during a multiday relay event

    NARCIS (Netherlands)

    A. van Maanen; B. Roest; M. Moen; F. Oort; P. Vergouwen; I Paul; P. Groenenboom; M. Smits

    2015-01-01

    Background: Sleep hygiene is important for sleep quality and optimal performance during the day. However, it is not always possible to follow sleep hygiene requirements. In multiday relay events, athletes have to sleep immediately after physical exertion and sometimes against their biological clock.

  3. Extreme meteorological events and nuclear facilities safety; Fenomenos meteorologicos extremos e a seguranca das instalacoes nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Patricia Moco Princisval

    2006-07-01

    An External Event is an event that originates outside the site and whose effects on the Nuclear Power Plants (NPP) should be considered. Such events could be of natural or human induced origin and should be identified and selected for design purposes during the site evaluation process. This work shows that the subtropics and mid latitudes of South America east of the Andes Mountain Range have been recognized as prone to severe convective weather. In Brazil, the events of tornadoes are becoming frequent; however there is no institutionalized procedure for a systematic documentation of severe weather. The information is done only for some scientists and by the newspapers. Like strong wind can affect the structural integrity of buildings or the pressure differential can affect the ventilation system, our concern is the safety of NPP and for this purpose the recommendations of International Atomic Energy Agency, Nuclear Regulatory Commission and Comissao Nacional de Energia Nuclear are showed and also a data base of tornadoes in Brazil is done. (author)

  4. Modelling Tradeoffs Evolution in Multipurpose Water Systems Operation in Response to Extreme Events

    Science.gov (United States)

    Mason, E.; Gazzotti, P.; Amigoni, F.; Giuliani, M.; Castelletti, A.

    2015-12-01

    Multipurpose water resource systems are usually operated on a tradeoff of the operating objectives, which - under steady state climatic and socio-economic boundary conditions - is supposed to ensure a fair and/or efficient balance among the conflicting interests. Extreme variability in the system's drivers might affect operators' risk aversion and force a change in the tradeoff. Properly accounting for these shifts is key to any rigorous retrospective assessment of operators' behavior and the associated system's performance. In this study, we explore how the selection of different optimal tradeoffs among the operating objectives is linked to the variations of the boundary conditions, such as, for example, drifting rainfall season or remarkable changes in crop and energy prices. We argue that tradeoff selection is driven by recent, extreme variations in system performance: underperforming on one of the operating objective target value should push the tradeoff toward the disadvantaged objective. To test this assumption, we developed a rational procedure to simulate the operators' tradeoff selection process. We map the selection onto a multi lateral negotiation process, where different multiple, virtual agents optimize different operating objectives. The agents periodically negotiate a compromise on the operating policy. The agent's rigidity in each negotiation round is determined by the recent system performances according to the specific objective it represents. The negotiation follows a set-based egocentric monotonic concession protocol: at each negotiation step an agent incrementally adds some options to the set of its acceptable compromises and (possibly) accepts lower and lower satisfying policies until an agreement is achieved. We apply this reiterated negotiation framework on the regulated Lake Como, Italy, simulating the lake dam operation and its recurrent updates over the last 50 years. The operation aims to balance shoreline flood prevention and irrigation

  5. Predicted 21st century changes in seasonal extreme precipitation events in the parallel climate model

    Energy Technology Data Exchange (ETDEWEB)

    Wehner, Michael F.

    2004-06-07

    Twenty-year return value of annual and seasonal maxima of daily precipitation are calculated from a set of transiently forced coupled general circulation model simulations. The magnitude and pattern of return values are found to be highly dependent on the seasonal cycle. A similar dependence is found for projected future changes in return values. The correlation between the spatial pattern of return value changes and mean precipitation changes is found to be low. Hence, the changes in mean precipitation do not provide significant information about changes in precipitation extreme values.

  6. Extreme Cosmic-Ray-Dominated-Regions: a new paradigm for high star formation density events in the Universe

    OpenAIRE

    Papadopoulos, Padeli P.; Thi, Wing-Fai; Miniati, Francesco; Viti, Serena

    2010-01-01

    We examine in detail the recent proposal that extreme Cosmic-Ray-Dominated-Regions (CRDRs) characterize the ISM of galaxies during events of high-density star formation, fundamentally altering its initial conditions (Papadopoulos 2010). Solving the coupled chemical and thermal state equations for dense UV-shielded gas reveals that the large cosmic ray energy densities in such systems (U_{CR} (few)x(10^3-10^4) U_{CR,Gal}) will indeed raise the minimum temperature of this phase (where the initi...

  7. Extreme events, intrinsic landforms and humankind: Post-tsunami scenario along Nagore–Velankanni coast, Tamil Nadu, India

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.

    average width were a f fected (Figure 3 d ). Scenario 3 ? A natural, functional and sustainable coas t Lessons learnt from extreme events have set a new par a- digm for coastal management worldwide 15,16,21 . Know l edge of coastal ecosystems....), Bookwell Press, New Delhi, 2000, pp. 201 ? 216. 6. Paul, A. K., Cyclonic storms and their impacts on West Bengal coast. In Procee dings of the I n ternational Seminar on Quaternary Sea Level Variation, Shoreline Displacement and Coastal Env i...

  8. Agriculture and Extreme Events: Modeling the Conjunctive Use of Groundwater and Surface Water

    Science.gov (United States)

    Munoz-Arriola, F.; Hanson, R. T.; Dettinger, M. D.; Cayan, D. R.

    2013-05-01

    Large-scale agriculture has become an important source of food to sustain population growth. Some of these agricultural areas are located in places where surface water supplies are subject to the effect of hydrometeorological phenomena such as droughts and floods. Under these conditions, ground water supplies can play an important role to sustain agriculture. The present work integrates surface and subsurface models [Variable Infiltration Capacity model (VIC) and MODFLOW and its Farming Process package (MODFLOW-FMP), respectively] to evaluate water supplies and demands in California's Central Valley. Extreme-wet to extreme-dry conditions were defined by applying the gamma distribution function to VIC-simulated streamflows flowing from the Sierra Nevada to the alluvial plains of Central Valley (1961 to 2003). Also, streamflows are MODFLOW-FMP's boundary conditions used to identify the influence of climate variability on the conjunctive use of ground water and surface water on the agricultural areas of Central Valley. Preliminary results show that available surface-water supplies satisfy crop irrigation requirements in the wet portion of Central Valley. However, ground water supplies cover large crop irrigation requirements in the south of Central Valley. Groundwater supplies in southern CV fuels the hydrological cycle in the in similar form as surface water supply does in the north. Evaluating the spatiotemporal variability of ground water supplies contributes to better understand the factors involved in the sustainability of the agriculture in Central Valley.

  9. Hybrid approach in statistical bias correction of projected precipitation for the frequency analysis of extreme events

    Science.gov (United States)

    Um, Myoung-Jin; Kim, Hanbeen; Heo, Jun-Haeng

    2016-08-01

    A general circulation model (GCM) can be applied to project future climate factors, such as precipitation and atmospheric temperature, to study hydrological and environmental climate change. Although many improvements in GCMs have been proposed recently, projected climate data are still required to be corrected for the biases in generating data before applying the model to practical applications. In this study, a new hybrid process was proposed, and its ability to perform bias correction for the prediction of annual precipitation and annual daily maxima, was tested. The hybrid process in this study was based on quantile mapping with the gamma and generalized extreme value (GEV) distributions and a spline technique to correct the bias of projected daily precipitation. The observed and projected daily precipitation values from the selected stations were analyzed using three bias correction methods, namely, linear scaling, quantile mapping, and hybrid methods. The performances of these methods were analyzed to find the optimal method for prediction of annual precipitation and annual daily maxima. The linear scaling method yielded the best results for estimating the annual average precipitation, while the hybrid method was optimal for predicting the variation in annual precipitation. The hybrid method described the statistical characteristics of the annual maximum series (AMS) similarly to the observed data. In addition, this method demonstrated the lowest root mean squared error (RMSE) and the highest coefficient of determination (R2) for predicting the quantiles of the AMS for the extreme value analysis of precipitation.

  10. Sensitivity of the WRF model to the lower boundary in an extreme precipitation event – Madeira Island case study

    Directory of Open Access Journals (Sweden)

    J. C. Teixeira

    2013-10-01

    Full Text Available Through the years, the advances in satellite technology made feasible the acquisition of information about the Earth surface, such as elevation and land use with great detail and resolution. This information can be included in numerical atmospheric models, updating them and providing a more detailed lower boundary, which in turn can improve the results of events forced by it. Given this, this work aims to study the sensitivity of the Weather Research and Forecast model to three different topography datasets as well as two different land use datasets in an extreme precipitation event. A test case study in which topography driven precipitation was dominant over Madeira Island was considered which triggered several flash floods and mudslides in the southern parts of the island. Model results show higher model skill in precipitation over Madeira leeward and in the windward wind flow, in spite of the non significant enhancement on the overall results with higher resolution datasets of topography and land use.

  11. On the physical causes of ENSO events and the ITCZ's extreme latitudinal displacements

    International Nuclear Information System (INIS)

    We predict the maximum latitudinal shifts of the Inter-Tropical convergence zone (ITCZ) over land masses due to variations in the surface or near-surface temperature fields. We also predict the mean locations of the ITCZ over oceans during northern hemisphere (NH) and southern hemisphere (SH) summers. All our predictions are shown to agree well with observations. Finally, on the basis of the association between the latitudinal location of the eastern pacific portion of the ITCZ and El Nino-Southern Oscillation (ENSO) events as well as some previous related work (Njau, 1985a; 1985b; 1986; 1987; 1988), we suggest possible physical causes of the ENSO events. (author). 39 refs, 1 fig., 2 tabs

  12. Adaptive Capacity of Households, Community Organizations and Institutions for Extreme Climate Events in the Philippines

    OpenAIRE

    Linda M Penalba; Elazegui, Dulce D.

    2011-01-01

    Tropical cyclone is the most commonly occurring natural hazard in the Philippines causing billions of pesos worth in socio-economic losses and other forms of damages. Analysis of 59-year data on Philippine typhoons revealed that their intensity had been increasing, especially since the 1990s. It is therefore important for people, communities, and institutions to enhance their capacity to adapt to typhoon events and improve resilience to their probable risks. This research work focused on loca...

  13. Secondary stressors and extreme events and disasters: a systematic review of primary research from 2010-2011.

    Science.gov (United States)

    Lock, Sarah; Rubin, G James; Murray, Virginia; Rogers, M Brooke; Amlôt, Richard; Williams, Richard

    2012-01-01

    Introduction Extreme events and disasters, such as earthquakes and floods, cause distress and are associated with some people developing mental disorders. Primary stressors inherent in many disasters can include injuries sustained or watching someone die. The literature recognises the distress which primary stressors cause and their association with mental disorders. Secondary stressors such as a lack of financial assistance, the gruelling process of submitting an insurance claim, parents' worries about their children, and continued lack of infrastructure can manifest their effects shortly after a disaster and persist for extended periods of time. Secondary stressors, and their roles in affecting people's longer-term mental health, should not be overlooked. We draw attention in this review to the nature of secondary stressors that are commonly identified in the literature, assess how they are measured, and develop a typology of these stressors that often affect people after extreme events. Methods We searched for relevant papers from 2010 and 2011 using MEDLINE®, Embase and PsycINFO®. We selected primary research papers that evaluated the associations between secondary stressors and distress or mental disorders following extreme events, and were published in English. We extracted information on which secondary stressors were assessed, and used thematic analysis to group the secondary stressors into a typology. Results Thirty-two relevant articles published in 2010 and 2011 were identified. Many secondary stressors were poorly defined and difficult to differentiate from primary stressors or other life events. We identified 11 categories of secondary stressors, though some extend over more than one category. The categories include: economic stressors such as problems with compensation, recovery of and rebuilding homes; loss of physical possessions and resources; health-related stressors; stress relating to education and schooling; stress arising from media

  14. Missing data imputation of climate datasets: implications to modeling extreme drought events

    Directory of Open Access Journals (Sweden)

    Gláucia Tatiana Ferrari

    2014-03-01

    Full Text Available Time series from weather stations in Brazil have several missing data, outliers and spurious zeroes. In order to use this dataset in risk and meteorological studies, one should take into account alternative methodologies to deal with these problems. This article describes the statistical imputation and quality control procedures applied to a database of daily precipitation from meteorological stations located in the State of Parana, Brazil. After imputation, the data went through a process of quality control to identify possible errors, such as: identical precipitation over seven consecutive days and precipitation values that differ significantly from the values in neighboring weather stations. Next, we used the extreme value theory to model agricultural drought, considering the maximum number of consecutive days with precipitation below 7 mm for the period between January and February, in the main soybean agricultural regions in the State of Parana.

  15. Non-linear time series extreme events and integer value problems

    CERN Document Server

    Turkman, Kamil Feridun; Zea Bermudez, Patrícia

    2014-01-01

    This book offers a useful combination of probabilistic and statistical tools for analyzing nonlinear time series. Key features of the book include a study of the extremal behavior of nonlinear time series and a comprehensive list of nonlinear models that address different aspects of nonlinearity. Several inferential methods, including quasi likelihood methods, sequential Markov Chain Monte Carlo Methods and particle filters, are also included so as to provide an overall view of the available tools for parameter estimation for nonlinear models. A chapter on integer time series models based on several thinning operations, which brings together all recent advances made in this area, is also included. Readers should have attended a prior course on linear time series, and a good grasp of simulation-based inferential methods is recommended. This book offers a valuable resource for second-year graduate students and researchers in statistics and other scientific areas who need a basic understanding of nonlinear time ...

  16. Initiation, maintenance, and properties of convection in an extreme rainfall event during SCMREX: Observational analysis

    Science.gov (United States)

    Wang, Hui; Luo, Yali; Jou, Ben Jong-Dao

    2014-12-01

    A long-lived mesoscale convective system (MCS) with extreme rainfall over the western coastal region of Guangdong on 10 May 2013 during the Southern China Monsoon Rainfall Experiment (SCMREX) is studied. The environmental conditions are characterized by little convective inhibition, low-lifting condensation level, moderate convective available potential energy and precipitable water, and lack of low-level jets from the tropical ocean. Repeated convective back building and subsequent northeastward "echo training" of convective cells are found during the MCS's development stages. However, the initiation/maintenance factors and organization of convection differ significantly during the earlier and later stages. From midnight to early morning, convection is continuously initiated as southeasterly flows near the surface impinge on the east side of mesoscale mountains near the coastal lines and then moves northeastward, leading to formation of two quasi-stationary rainbands. From early morning to early afternoon, new convection is repeatedly triggered along a mesoscale boundary between precipitation-induced cold outflows and warm air from South China Sea and Gulf of Tokin, resulting in the formation of "band training" of several parallel rainbands that move eastward in a later time, i.e., two scales of "training" of convective elements are found. As the MCS dissipates, a stronger squall line moves into the region from the west and passes over within about 3.5 h, contributing about 10%-15% to the total rainfall amount. It is concluded that terrain, near-surface winds, warm advection from the upstream ocean in the boundary layer, and precipitation-generated cold outflows play important roles in initiating and maintaining the extreme rain-producing MCS.

  17. Improved understanding of an extreme rainfall event at the Himalayan foothills – a case study using COSMO

    Directory of Open Access Journals (Sweden)

    Prabhakar Shrestha

    2015-05-01

    Full Text Available In recent years, an increased occurrence of loss and damage of property and human casualties over the southern rim area of the Himalayas, caused by landslides following intense rainfall events, has been reported. An analysis of Tropical Rainfall Measuring Mission (TRMM-gridded rainfall data shows that events with an exceedance probability of 1.6% for 200 mm/d rainfall are common over this region during the monsoon season. An improved understanding of the mechanisms, which lead to such events, is important for their prediction and to estimate the impact of climate change on their recurrence. In this study, we analyse such an extreme precipitation event, which hit the Uttarakhand region of the central Himalayas on 13 September 2012. We use the operational regional weather forecast model COSMO at a convection-permitting resolution of 2.8 km to simulate this event. The spatial pattern of daily-accumulated precipitation and atmospheric state profiles simulated by the model compared well with the TRMM-gridded data and radiosonde observations, which adds confidence to our model results. Our analysis suggests a three-step mechanism leading to this event: (1 development of an easterly low-level wind along the Gangetic Plain caused by a low pressure system over the central Gangetic Plain; (2 convergence of moisture over the north-western part of India, leading to an increase of potential instability of the air mass along the valley recesses, which is capped by an inversion located above the ridgeline; and (3 strengthening of the north-westerly flow above the ridges, which supports the lifting of the potentially unstable air over the protruding ridge of the foothills of the Himalayas and triggers shallow convection, which on passing through adjacent folds initiates deep convection.

  18. Household and Community Assets and Farmers’ Adaptation to Extreme Weather Event:the Case of Drought in China

    Institute of Scientific and Technical Information of China (English)

    WANG Yang-jie; HUANG Ji-kun; WANG Jin-xia

    2014-01-01

    Under climate change, rising frequency and serious extreme weather events have challenged agricultural production. Designing appropriate adaptation measures to the extreme weather events require rigorous and empirical analysis. The overall goals of this study are to understand physical adaptation measures taken by farmers and the impacts of household and community assets on farmers’ adaptation when they face drought. The analyses are based on a unique data set collected from a household survey in three provinces in China. The survey results show that though not common on annual basis, some farmers did use physical adaptation measures to ifght drought. Regression analysis reveals that both household and community assets significantly affect farmers’ adaptation behaviors. Improving households’ social capital and wealth, communities’ network and access to government’s anti-drought service can facilitate farmers’ adaptation to drought. Results indicate that community’s irrigation infrastructure and physical adaptation taken by farmers can substitute each other. Further analysis shows that the households taking adaptation measures have higher crop yields than those without taking these measures. The paper concludes with several policy implications.

  19. Using Discrete Event Simulation for Programming Model Exploration at Extreme-Scale: Macroscale Components for the Structural Simulation Toolkit (SST).

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Jeremiah J; Kenny, Joseph P.

    2015-02-01

    Discrete event simulation provides a powerful mechanism for designing and testing new extreme- scale programming models for high-performance computing. Rather than debug, run, and wait for results on an actual system, design can first iterate through a simulator. This is particularly useful when test beds cannot be used, i.e. to explore hardware or scales that do not yet exist or are inaccessible. Here we detail the macroscale components of the structural simulation toolkit (SST). Instead of depending on trace replay or state machines, the simulator is architected to execute real code on real software stacks. Our particular user-space threading framework allows massive scales to be simulated even on small clusters. The link between the discrete event core and the threading framework allows interesting performance metrics like call graphs to be collected from a simulated run. Performance analysis via simulation can thus become an important phase in extreme-scale programming model and runtime system design via the SST macroscale components.

  20. The characteristics of clusters of weather and extreme climate events in China during the past 50 years

    International Nuclear Information System (INIS)

    The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years. The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s, and its strength was enhanced. On the other hand, the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale. Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years, and have different cluster characteristics because of their definitions. Regions with high clustered indexes are concentrated in southern China. The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years. (geophysics, astronomy, and astrophysics)

  1. Risk-based generation dispatch in the power grid for resilience against extreme weather events

    Science.gov (United States)

    Javanbakht, Pirooz

    Natural disasters have been considered as one of the main causes of the largest blackouts in North America. When it comes to power grid resiliency against natural hazards, different solutions exist that are mainly categorized based on the time-frame of analysis. At the design stage, robustness and resiliency may be improved through redundant designs and inclusion of advanced measurement, monitoring, control and protection systems. However, since massive destructive energy may be released during the course of a natural disaster (such as a hurricane) causing large-scale and widespread disturbances, design-stage remedies may not be sufficient for ensuring power grid robustness. As a result, to limit the consequent impacts on the operation of the power grid, the system operator may be forced to take immediate remedial actions in real-time. To effectively manage the disturbances caused by severe weather events, weather forecast information should be incorporated into the operational model of the power grid in order to predict imminent contingencies. In this work, a weather-driven generation dispatch model is developed based on stochastic programming to provide a proactive solution for power grid resiliency against imminent large-scale disturbances. Hurricanes and ice storms are studied as example disaster events to provide numerical results. In this approach, the statistics of the natural disaster event are taken into account along with the expected impact on various power grid components in order to determine the availability of the grid. Then, a generation dispatch strategy is devised that helps operate the grid subject to weather-driven operational constraints.

  2. Impacts of the January 2014 extreme rainfall event on transportation network in the Alps Maritimes (France)

    Science.gov (United States)

    Voumard, Jeremie; Penna, Ivanna; Jaboyedoff, Michel; Derron, Marc-Henri

    2014-05-01

    Road networks in mountain areas are highly inter-dependent systems, and hillslope processes such as landslides are main drivers of infrastructure detriment and transportation disruptions. Besides the structural damages, economic losses are also related to road and surrounding slope maintenance, as well as due to the disruption of transportation of goods, inaccessibility of tourist resorts, etc. 16-17th January 2014, an intense rainfall event was recorded in the Alpes Maritimes from the southern part of France. According to meteorological data, it was the highest since the 70's. This rainfall triggered numerous landslides (rockfalls, earth flows and debris flows), mostly on January 17th. There were no casualties registered due to hillslope processes, but several houses were damaged, some populations living in the Var valley along the RM 2205 road were isolated, and several roads were partially and totally blocked. 1.5 km upstream the village of Saint-Sauveur-sur-Tinée, 150 m3 of rock detached from the slope and blocked the road, after which temporary traffic interruptions due to road works lasted around one week. In the Menton area, where hillslopes are highly urbanized, the volume of rocks involved in slope failures was so large that materials removed to reestablish the traffic had to be placed in transitory storage sites. The average landslide volume was estimated at around 100 m3. Most of the landslides occurred in slopes cut during road and houses constructions. Several trucks were needed to clean up materials, giving place to traffic jams, etc. (some single events reached around 400 m3). The aim of this study is to document the impact on transportation networks caused by this rainfall event. Damages and consequences for the traffic were documented during a field visit, obtained from secondary information, as well as by the aid of a drone in the case of inaccessible areas.

  3. Spatial vulnerability under extreme events: a case of Asian dust storm's effects on children's respiratory health.

    Science.gov (United States)

    Yu, Hwa-Lung; Yang, Chiang-Hsing; Chien, Lung-Chang

    2013-04-01

    Asian dust storm (ADS) events have raised concerns regarding their adverse impact on human health. Whether ADS events can result in the heterogeneity of health impacts on children across space and time has not been studied. The goal of this study is to examine the spatial vulnerability impact of ADS events on children's respiratory health geographically and to analyze any patterns related to ADS episodes. From 1998 to 2007, data from both preschool children's and schoolchildren's daily respiratory clinic visits, gathered from patients located in 41 districts of Taipei City and New Taipei City, are analyzed in a Bayesian spatiotemporal model in order to investigate the interaction between spatial effects and ADS episodes. When adjusting for the temporal effect, air pollutants, and temperature, the spatial pattern explicitly varies during defined study periods: non-ADS periods, ADS periods, and post-ADS periods. Compared to non-ADS periods, the relative rate of children's respiratory clinic visits significantly reduced 0.74 to 0.99 times in most districts during ADS periods, while the relative rate rose from 1.01 to 1.11 times in more than half of districts during post-ADS periods, especially in schoolchildren. This spatial vulnerability denotes that the significantly increased relative rate of respiratory clinic visits during post-ADS periods is primarily located in highly urbanized areas for both children's populations. Hence, the results of this study suggest that schoolchildren are particularly more vulnerable to the health impacts of ADS exposure in terms of higher excessive risks over a larger spatial extent than preschool children, especially during post-ADS periods. PMID:23403144

  4. Building hazard maps of extreme daily rainy events from PDF ensemble, via REA method, on Senegal River Basin

    Directory of Open Access Journals (Sweden)

    J. D. Giraldo

    2011-04-01

    Full Text Available The Sudano-Sahelian zone of West Africa, one of the poorest of the Earth, is characterized by high rainfall variability and rapid population growth. In this region, heavy storm events frequently cause extensive damage. Nonetheless, the projections for change in extreme rainfall values have shown a great divergence between Regional Climate Models (RCM, increasing the forecast uncertainty. Novel methodologies should be applied, taking into account both the variability provided by different RCMs, as well as the non-stationary nature of time series for the building of hazard maps of extreme rainfall events. The present work focuses in the probability density functions (PDFs-based evaluation and a simple quantitative measure of how well each RCM considered can capture the observed annual maximum daily rainfall (AMDR series on the Senegal River basin. Since meaningful trends have been detected in historical rainfall time series for the region, non-stationary probabilistic models were used to fit the PDF parameters to the AMDR time series. In the development of PDF ensemble by bootstrapping techniques, Reliability Ensemble Averaging (REA maps were applied to score the RCMs. The REA factors were computed using a metric to evaluate the agreement between observed -or best estimated- PDFs, and that simulated with each RCM. The assessment of plausible regional trends associated to the return period, from the hazard maps of AMDR, showed a general rise, owing to an increase in the mean and the variability of extreme precipitation. These spatial-temporal distributions could be considered by local stakeholders in such a way as to reach a better balance between mitigation and adaptation.

  5. Comparative analysis of the extreme temperature event change over Northeast China and Hokkaido, Japan from 1951 to 2011

    Science.gov (United States)

    Wang, Lei; Wu, Zhengfang; Wang, Fuxue; Du, Haibo; Zong, Shengwei

    2016-04-01

    On the basis of the daily minimum (T min), mean (T mean), and maximum (T max) temperature records of 25 meteorological stations in Northeast China (NEC) and 10 weather stations in Hokkaido, Japan (HKD), from 1951 to 2011, we comparatively analyzed the change in extreme temperature events and the relationship of these events with the mean value. Results showed that for the extreme lowest temperature (ELT) frequency, approximately 96 % of the stations exhibited decreasing trends ranging from -0.63 to 0 days/decade in NEC, whereas all the stations in HKD showed decreasing trends ranging from -0.4 to 0 days/decade. However, the average decrease in amplitude of 0.24 days/decade in HKD was significantly less than the 0.27 days/decade average in NEC. The extreme highest temperature (EHT) frequency trends in the two regions showed insignificant increases. Notable decreasing trends for the ELT intensity were found at -0.9 to 0 %/decade in 92 % of the stations in NEC and -1.1 to 0 %/decade in 90 % of the stations in HKD. Inversely, increasing trends in EHT intensity were observed in 80 % of the stations over HKD, ranging from 0.06 to 0.32 %/decade, and the majority of the stations (64 %) showed increasing trends in NEC. T mean and T min had strong negative correlations with the ELT intensity in NEC, whereas T mean and T min had strong significant negative correlations with the ELT frequency in HKD. T min, T mean, and T max between NEC and HKD exhibited strong significant positive correlations. The frequency and intensity of the ELT in both regions showed significant positive correlations.

  6. Sensitivity of seasonal weather prediction and extreme precipitation events to soil moisture initialization uncertainty using SMOS soil moisture products

    Science.gov (United States)

    Khodayar-Pardo, Samiro; Lopez-Baeza, Ernesto; Coll Pajaron, M. Amparo

    Sensitivity of seasonal weather prediction and extreme precipitation events to soil moisture initialization uncertainty using SMOS soil moisture products (1) S. Khodayar, (2) A. Coll, (2) E. Lopez-Baeza (1) Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology (KIT), Karlsruhe Germany (2) University of Valencia. Earth Physics and Thermodynamics Department. Climatology from Satellites Group Soil moisture is an important variable in agriculture, hydrology, meteorology and related disciplines. Despite its importance, it is complicated to obtain an appropriate representation of this variable, mainly because of its high temporal and spatial variability. SVAT (Soil-Vegetation-Atmosphere-Transfer) models can be used to simulate the temporal behaviour and spatial distribution of soil moisture in a given area and/or state of the art products such as the soil moisture measurements from the SMOS (Soil Moisture and Ocean Salinity) space mission may be also convenient. The potential role of soil moisture initialization and associated uncertainty in numerical weather prediction is illustrated in this study through sensitivity numerical experiments using the SVAT SURFEX model and the non-hydrostatic COSMO model. The aim of this investigation is twofold, (a) to demonstrate the sensitivity of model simulations of convective precipitation to soil moisture initial uncertainty, as well as the impact on the representation of extreme precipitation events, and (b) to assess the usefulness of SMOS soil moisture products to improve the simulation of water cycle components and heavy precipitation events. Simulated soil moisture and precipitation fields are compared with observations and with level-1(~1km), level-2(~15 km) and level-3(~35 km) soil moisture maps generated from SMOS over the Iberian Peninsula, the SMOS validation area (50 km x 50 km, eastern Spain) and selected stations, where in situ measurements are available covering different vegetation cover

  7. Modelling overland flow during extreme precipitation events: influence of precipitation aggregation level, soil development and climate change

    Science.gov (United States)

    Leterme, B.; Beerten, K.

    2012-04-01

    In this study, the sensitivity of overland flow modelling to selected parameters in a small (several km2) recharge area in the Campine region, northern Belgium, is investigated. In first instance, the amount of overland flow is estimated according to the temporal resolution of rainfall data. In a second step, the effect of soil development and climate change is incorporated in the model as well. The study focuses on the extreme event of 23 August 2011, when ~40 mm of rain fell in ~25 minutes in the investigation area. Precipitation was recorded with a one-minute temporal resolution. The generation of saturation overland flow during this event is simulated with the van Genuchten-Mualem model (using HYDRUS-1D) for a Haplic Podzol typical of the area. The hydraulic barrier eventually causing overland flow is the Bh horizon at shallow depth, characterised by a saturated hydraulic conductivity (Ksat) of 4.5×10-6 m/s. The sensitivity of overland flow to the temporal resolution used in the model is investigated for daily, hourly, 20-minute and 10-minute time steps. Results show that the aggregation level has a critical influence on the amount of saturation overland flow, ranging from 0 to 4.0 mm. Landscape and soil evolution studies in the vicinity of the site indicate that cemented podzols may develop in several thousands of years, thus decreasing the Ksat of the Bh horizon by several orders of magnitude. On this time scale, global climate evolution is also expected to have an impact on the precipitation regime, possibly resulting in more severe extreme events for a given return period. These two processes are simulated respectively by decreasing Ksat by one or two orders of magnitude and by increasing rainfall rate by 4 and 16% (and potential evapotranspiration by 13 and 25%, based on the scenarios for the period 2071-2100 of the CCI-HYDR project; Baguis et al., 2009). Results show that in the most defavourable case, overland flow during the extreme event simulated

  8. Disentangling event-scale hydrologic flow partitioning in mountains of the Korean Peninsula under extreme precipitation

    Science.gov (United States)

    Shope, Christopher L.

    2016-07-01

    Mountainous headwaters include a variety of spatial landscape units; however, the flow contribution from different hydrologic components is complex and often unclear. In addition to complex landscape controls, temporal meteorological drivers play an important role in the distribution between surface runoff and subsurface storage changes. This spatiotemporal variability in partitioning can influence catchment-wide flow accumulation and nutrient and sediment loading. We use a multi-year, multi-method analysis of stable isotopes, geochemical indicators, and discharge distributed throughout the Haean catchment in South Korea to identify temporal variability in hydrologic flow partitioning from surface runoff, springs, shallow interflow, and groundwater under monsoonal conditions. By combining a weighted, multi-method discharge approach, high frequency, synoptic, catchment-wide isotopic and geochemical sampling, and baseflow analysis, we characterize watershed-scale spatiotemporal hydrologic flow partitioning. Meteorological drivers are spatially variable throughout the catchment and temporally between individual events. Baseflow contributions in the high elevation, forested areas are up to 50%, while the majority of the catchment is approximately 20%. Our study builds on previously reported seasonality of isotopic signatures by quantifying trends in distributed event-based partitioning of isotopic tracers. We demonstrate that high frequency flow partitioning can accurately be determined in mountainous topography with high precipitation and that there is a need for multiple method characterizations. Our results further show the benefit of spatially distributed synoptic sampling for process understanding of hydrologic partitioning throughout the watersheds.

  9. Understanding future projected changes and trends in extreme precipitation and streamflow events in ten Polish catchments

    Science.gov (United States)

    Meresa, Hadush; Romanowicz, Renata; Napiorkoski, Jaroslaw

    2016-04-01

    increased flows, with strong seasonal changes. The results of the DHR analysis show that hydro-climatic extremes are characterized by oscillatory behavior at different time scales. Acknowledgements: This work was supported by the project CHIHE (Climate Change Impact on Hydrological Extremes), carried out in the Institute of Geophysics Polish Academy of Sciences, funded by Norway Grants (contract No. Pol-Nor/196243/80/2013). The climate, water level and flow data were provided by the Institute of Meteorology and Water Management (IMGW), Poland.

  10. Climate change, variability and extreme events : risk assessment and management strategies in a Peach cultivated area in Italy.

    Science.gov (United States)

    Alfieri, Silvia Maria; De Lorenzi, Francesca; Basile, Angelo; Bonfante, Antonello; Missere, Daniele; Menenti, Massimo

    2014-05-01

    Climate change in Mediterranean area is likely to reduce precipitation amounts and to increase temperature thus affecting the timing of development stages and the productivity of crops. Further, extreme weather events are expected to increase in the future leading to significant increase in agricultural risk. Some strategies for effectively managing risks and adapting to climate change involve adjustments to irrigation management and use of different varieties. We quantified the risk on Peach production in an irrigated area of "Emilia Romagna" region ( Italy) taking into account the impact on crop yield due to climate change and variability and to extreme weather events as well as the ability of the agricultural system to modulate this impact (adaptive capacity) through changes in water and crop management. We have focused on climatic events causing insufficient water supply to crops, while taking into account the effect of climate on the duration and timing of phenological stages. Further, extreme maximum and minimum temperature events causing significant reduction of crop yield have been considered using phase-specific critical temperatures. In our study risk was assessed as the product of the probability of a damaging event (hazard), such as drought or extreme temperatures, and the estimated impact of such an event (vulnerability). To estimate vulnerability we took into account the possible options to reduce risk, by combining estimates of the sensitivity of the system (negative impact on crop yield) and its adaptive capacity. The latter was evaluated as the relative improvement due to alternate management options: the use of alternate varieties or the changes in irrigation management. Vulnerability was quantified using cultivar-specific thermal and hydrologic requirements of a set of cultivars determined by experimental data and from scientific literature. Critical temperatures determining a certain reduction of crop yield have been estimated and used to assess

  11. Improving pan-European hydrological simulation of extreme events through statistical bias correction of RCM-driven climate simulations

    Directory of Open Access Journals (Sweden)

    R. Rojas

    2011-08-01

    Full Text Available In this work we asses the benefits of removing bias in climate forcing data used for hydrological climate change impact assessment at pan-European scale, with emphasis on floods. Climate simulations from the HIRHAM5-ECHAM5 model driven by the SRES-A1B emission scenario are corrected for bias using a histogram equalization method. As target for the bias correction we employ gridded interpolated observations of precipitation, average, minimum, and maximum temperature from the E-OBS data set. Bias removal transfer functions are derived for the control period 1961–1990. These are subsequently used to correct the climate simulations for the control period, and, under the assumption of a stationary error model, for the future time window 2071–2100. Validation against E-OBS climatology in the control period shows that the correction method performs successfully in removing bias in average and extreme statistics relevant for flood simulation over the majority of the European domain in all seasons. This translates into considerably improved simulations with the hydrological model of observed average and extreme river discharges at a majority of 554 validation river stations across Europe. Probabilities of extreme events derived employing extreme value techniques are also more closely reproduced. Results indicate that projections of future flood hazard in Europe based on uncorrected climate simulations, both in terms of their magnitude and recurrence interval, are likely subject to large errors. Notwithstanding the inherent limitations of the large-scale approach used herein, this study strongly advocates the removal of bias in climate simulations prior to their use in hydrological impact assessment.

  12. Extreme star formation events in quasar hosts over ${\\bf0.5<\\textit{z}<4}$

    CERN Document Server

    Pitchford, Lura K; Feltre, Anna; Farrah, Duncan; Clarke, Charlotte; Harris, Kathryn; Hurley, Peter; Oliver, Sebastian; Page, Mathew; Wang, Lingyu

    2016-01-01

    We explore the relationship between active galactic nuclei and star formation in a sample of 513 optically luminous type 1 quasars up to redshifts of $\\sim$4 hosting extremely high star formation rates (SFRs). The quasars are selected to be individually detected by the \\textit{Herschel} SPIRE instrument at $> $3$\\sigma$ at 250 $\\mu$m, leading to typical SFRs of order of 1000 M$_{\\odot}$yr$^{-1}$. We find the average SFRs to increase by almost a factor 10 from $z\\sim0.5$ to $z\\sim3$, mirroring the rise in the comoving SFR density over the same epoch. However, we find that the SFRs remain approximately constant with increasing accretion luminosity for accretion luminosities above 10$^{12}$ L$_{\\odot}$. We also find that the SFRs do not correlate with black hole mass. Both of these results are most plausibly explained by the existence of a self-regulation process by the starburst at high SFRs, which controls SFRs on time-scales comparable to or shorter than the AGN or starburst duty cycles. We additionally find ...

  13. Recurring features of extreme autumnall rainfall events on the Veneto coastal area

    Directory of Open Access Journals (Sweden)

    A. Barbi

    2012-08-01

    Full Text Available Recent recurring episodes of heavy flash flood-producing rainfall events on the Veneto coastal area have renewed the interest in documenting the frequency and key dynamical ingredients of such events. A climatological analysis of the precipitation in Veneto reveals that, in comparison with the rest of the region, the coastal area is characterized by fewer rain days, lower rainfall accumulations, yet more days with heavy precipitation. If set in relation to the yearly rainfall, daily accumulation can reach values as high as 40% of the yearly total rainfall, more regularly between 15% and 30%, often in periods of 12 h or less.

    Four such heavy rainfall events were analyzed and synthetically described to highlight key ingredients which appear instrumental in producing the high rainfall accumulations. These comprise an upper-level trough elongating or cutting off into the Western Mediterranean basin after a period of one to two weeks of anticyclonic fair weather conditions with temperatures above normal. The moisture supply over the Adriatic onto north-eastern Italy is favoured by above normal sea surface temperatures, enhanced advection by a surface low in the Gulf of Genoa, and in three of the four cases, an additional surface low over southern Italy. The air flows associated with the upper-level trough for the cases discussed were of moderate to weak intensity, and convectively conditionally unstable. The flow intensity was such that the lower tropospheric portion was blocked by and forced to flow around the Alpine barrier, i.e. manifesting as a north-easterly, low-level flow over much of the north-eastern Italian plains. This blocked flow seemed to interact with the larger-scale synoptic flow to form a distinct and persistent low-level convergence in the area of the Veneto coast.

    It is suggested that these low-level convergence patterns are key in releasing the convective instability present in the larger-scale flow just on the

  14. Possible effect of extreme solar energetic particle event of 20 January 2005 on polar stratospheric aerosols: direct observational evidence

    Directory of Open Access Journals (Sweden)

    I. A. Mironova

    2011-05-01

    Full Text Available Energetic cosmic rays are the main source of ionization of the low-middle atmosphere, leading to associated changes in atmospheric properties. Via the hypothetical influence of ionization on aerosol growth and facilitated formation of cloud condensation nuclei, this may be an important indirect link relating solar variability to climate. This effect is highly debated, however, since the proposed theoretical mechanisms still remain illusive and qualitative, and observational evidence is inconclusive and controversial. Therefore, important questions regarding the existence and magnitude of the effect, and particularly the fraction of aerosol particles that can be formed and grow large enough to influence cloud condensation nuclei (CCN, are still open. Here we present empirical evidence of the possible effect caused by cosmic rays upon polar stratospheric aerosols, based on a case study of an extreme solar energetic particle (SEP event of 20 January 2005. Using aerosol data obtained over polar regions from different satellites with optical instruments that were operating during January 2005, such as the Stratospheric Aerosol and Gas Experiment III (SAGE III, and Optical Spectrograph and Infrared Imaging System (OSIRIS, we found a significant simultaneous change in aerosol properties in both the southern and northern polar regions in temporal association with the SEP event. We speculate that ionization of the atmosphere, which was abnormally high during this extreme SEP event, might have led to formation of new particles and/or growth of preexisting ultrafine particles up to the size of CCN. However, a detailed interpretation of the effect is left for subsequent studies. This is the first time high vertical resolution measurements have been used to provide evidence for the probable production of stratospheric CCN from cosmic ray induced ionization.

  15. Increased Extreme Hydrological Events and Decreased Water Supply Availability for the Southwestern United States Projected by Mid-Century

    Science.gov (United States)

    Pagan, B. R.; Ashfaq, M.; Rastogi, D.; Naz, B. S.; Kao, S. C.; Mei, R.; Kendall, D. R.; Pal, J. S.

    2015-12-01

    Semi-arid Southern California relies primarily on imported water originating mostly from snowpack in basins outside of the region including the San-Joaquin River, Tulare Lake, Sacramento River, Owens Valley, Mono Lake, and Colorado River basins. This study provides an integrated ensemble approach to assessing climate change impacts on the hydrologic cycle and hydrologic extremes for all water supplies to Southern California. Output from 10 global climate models is used to force a regional climate model and hydrological model resulting in high-resolution 4.17-km output for the region. Greenhouse gas concentrations are prescribed according to historical values for the present-day (1965-2005) and the IPCC Representative Concentration Pathway 8.5 for the near to mid term future (2010-2050). On the annual timescale, temperature, precipitation and evaporation increase throughout the majority of the study area. With increased temperatures, precipitation is less likely to fall as snow, decreasing snowpack and natural storage and shifting peak flows to earlier in the year. Daily annual maximum runoff and precipitation events are projected to significantly increase in intensity and frequency by mid-century. The 50-year event, for example, becomes approximately five times more likely in the Colorado River basin and twice as likely in the other basins. In densely populated coastal Southern Californian cities, extreme flood events become three to five times as likely substantially increasing the risk of overburdening flood control systems and potential widespread flooding. The escalating likelihood of the combined effects of runoff occurring earlier in the year and in significantly higher amounts poses a substantial flood control risk requiring adaptation measures such as water release from reservoirs. Significant snowpack reductions and increased flood risk will likely necessitate additional multiyear storage solutions for urban and agricultural regions in the Southwestern US.

  16. Jellyfish: The origin and distribution of extreme ram-pressure stripping events in massive galaxy clusters

    CERN Document Server

    McPartland, Conor; Roediger, Elke; Blumenthal, Kelly

    2015-01-01

    We investigate the observational signatures and physical origin of ram-pressure stripping (RPS) in 63 massive galaxy clusters at $z=0.3-0.7$, based on images obtained with the Hubble Space Telescope. Using a training set of a dozen "jellyfish" galaxies identified earlier in the same imaging data, we define morphological criteria to select 211 additional, less obvious cases of RPS. Spectroscopic follow-up observations of 124 candidates so far confirmed 53 as cluster members. For the brightest and most favourably aligned systems we visually derive estimates of the projected direction of motion based on the orientation of apparent compression shocks and debris trails. Our findings suggest that the onset of these events occurs primarily at large distances from the cluster core ($>400$ kpc), and that the trajectories of the affected galaxies feature high impact parameters. Simple models show that such trajectories are highly improbable for galaxy infall along filaments but common for infall at high velocities, eve...

  17. Using coarse GPS data to quantify city-scale transportation system resilience to extreme events

    CERN Document Server

    Donovan, Brian

    2015-01-01

    This article proposes a method to quantitatively measure the resilience of transportation systems using GPS data from taxis. The granularity of the GPS data necessary for this analysis is relatively coarse; it only requires coordinates for the beginning and end of trips, the metered distance, and the total travel time. The method works by computing the historical distribution of pace (normalized travel times) between various regions of a city and measuring the pace deviations during an unusual event. This method is applied to a dataset of nearly 700 million taxi trips in New York City, which is used to analyze the transportation infrastructure resilience to Hurricane Sandy. The analysis indicates that Hurricane Sandy impacted traffic conditions for more than five days, and caused a peak delay of two minutes per mile. Practically, it identifies that the evacuation caused only minor disruptions, but significant delays were encountered during the post-disaster reentry process. Since the implementation of this me...

  18. Armed-conflict risks enhanced by climate-related disasters in ethnically fractionalized countries.

    Science.gov (United States)

    Schleussner, Carl-Friedrich; Donges, Jonathan F; Donner, Reik V; Schellnhuber, Hans Joachim

    2016-08-16

    Social and political tensions keep on fueling armed conflicts around the world. Although each conflict is the result of an individual context-specific mixture of interconnected factors, ethnicity appears to play a prominent and almost ubiquitous role in many of them. This overall state of affairs is likely to be exacerbated by anthropogenic climate change and in particular climate-related natural disasters. Ethnic divides might serve as predetermined conflict lines in case of rapidly emerging societal tensions arising from disruptive events like natural disasters. Here, we hypothesize that climate-related disaster occurrence enhances armed-conflict outbreak risk in ethnically fractionalized countries. Using event coincidence analysis, we test this hypothesis based on data on armed-conflict outbreaks and climate-related natural disasters for the period 1980-2010. Globally, we find a coincidence rate of 9% regarding armed-conflict outbreak and disaster occurrence such as heat waves or droughts. Our analysis also reveals that, during the period in question, about 23% of conflict outbreaks in ethnically highly fractionalized countries robustly coincide with climatic calamities. Although we do not report evidence that climate-related disasters act as direct triggers of armed conflicts, the disruptive nature of these events seems to play out in ethnically fractionalized societies in a particularly tragic way. This observation has important implications for future security policies as several of the world's most conflict-prone regions, including North and Central Africa as well as Central Asia, are both exceptionally vulnerable to anthropogenic climate change and characterized by deep ethnic divides. PMID:27457927

  19. Climate and climate-related issues for the safety assessment SR-Can

    Energy Technology Data Exchange (ETDEWEB)

    Naeslund, Jens-Ove (comp.)

    2006-11-15

    The purpose of this report is to document current scientific knowledge of the climate-related conditions and processes relevant to the long-term safety of a KBS-3 repository to a level required for an adequate treatment in the safety assessment SR-Can. The report also includes a concise background description of the climate system. The report includes three main chapters: A description of the climate system (Chapter 2); Identification and discussion of climate-related issues (Chapter 3); and, A description of the evolution of climate-related conditions for the safety assessment (Chapter 4). Chapter 2 includes an overview of present knowledge of the Earth climate system and the climate conditions that can be expected to occur in Sweden on a 100,000 year time perspective. Based on this, climate-related issues relevant for the long-term safety of a KBS-3 repository are identified. These are documented in Chapter 3 'Climate-related issues' to a level required for an adequate treatment in the safety assessment. Finally, in Chapter 4, 'Evolution of climate-related conditions for the safety assessment' an evolution for a 120,000 year period is presented, including discussions of identified climate-related issues of importance for repository safety. The documentation is from a scientific point of view not exhaustive, since such a treatment is neither necessary for the purposes of the safety assessment nor possible within the scope of a safety assessment. As further described in the SR-Can Main Report and in the Features Events and Processes report, the content of the present report has been audited by comparison with FEP databases compiled in other assessment projects. This report follows as far as possible the template for documentation of processes regarded as internal to the repository system. However, the term processes is not used in this report, instead the term issue has been used. Each issue includes a set of processes together resulting in the

  20. Climate and climate-related issues for the safety assessment SR-Can

    International Nuclear Information System (INIS)

    The purpose of this report is to document current scientific knowledge of the climate-related conditions and processes relevant to the long-term safety of a KBS-3 repository to a level required for an adequate treatment in the safety assessment SR-Can. The report also includes a concise background description of the climate system. The report includes three main chapters: A description of the climate system (Chapter 2); Identification and discussion of climate-related issues (Chapter 3); and, A description of the evolution of climate-related conditions for the safety assessment (Chapter 4). Chapter 2 includes an overview of present knowledge of the Earth climate system and the climate conditions that can be expected to occur in Sweden on a 100,000 year time perspective. Based on this, climate-related issues relevant for the long-term safety of a KBS-3 repository are identified. These are documented in Chapter 3 'Climate-related issues' to a level required for an adequate treatment in the safety assessment. Finally, in Chapter 4, 'Evolution of climate-related conditions for the safety assessment' an evolution for a 120,000 year period is presented, including discussions of identified climate-related issues of importance for repository safety. The documentation is from a scientific point of view not exhaustive, since such a treatment is neither necessary for the purposes of the safety assessment nor possible within the scope of a safety assessment. As further described in the SR-Can Main Report and in the Features Events and Processes report, the content of the present report has been audited by comparison with FEP databases compiled in other assessment projects. This report follows as far as possible the template for documentation of processes regarded as internal to the repository system. However, the term processes is not used in this report, instead the term issue has been used. Each issue includes a set of processes together resulting in the behaviour of a

  1. Fuel treatments and landform modify landscape patterns of burn severity in an extreme fire event.

    Science.gov (United States)

    Prichard, Susan J; Kennedy, Maureen C

    2014-04-01

    Under a rapidly warming climate, a critical management issue in semiarid forests of western North America is how to increase forest resilience to wildfire. We evaluated relationships between fuel reduction treatments and burn severity in the 2006 Tripod Complex fires, which burned over 70,000 ha of mixed-conifer forests in the North Cascades range of Washington State and involved 387 past harvest and fuel treatment units. A secondary objective was to investigate other drivers of burn severity including landform, weather, vegetation characteristics, and a recent mountain pine beetle outbreak. We used sequential autoregression (SAR) to evaluate drivers of burn severity, represented by the relative differenced Normalized Burn Ratio index, in two study areas that are centered on early progressions of the wildfire complex. Significant predictor variables include treatment type, landform (elevation), fire weather (minimum relative humidity and maximum temperature), and vegetation characteristics, including canopy closure, cover type, and mountain pine beetle attack. Recent mountain pine beetle damage was a statistically significant predictor variable with red and mixed classes of beetle attack associated with higher burn severity. Treatment age and size were only weakly correlated with burn severity and may be partly explained by the lack of treatments older than 30 years and the low rates of fuel succession in these semiarid forests. Even during extreme weather, fuel conditions and landform strongly influenced patterns of burn severity. Fuel treatments that included recent prescribed burning of surface fuels were particularly effective at mitigating burn severity. Although surface and canopy fuel treatments are unlikely to substantially reduce the area burned in regional fire years, recent research, including this study, suggests that they can be an effective management strategy for increasing forest landscape resilience to wildfires. PMID:24834742

  2. Large-scale factors in tropical and extratropical cyclone transition and extreme weather events.

    Science.gov (United States)

    Pezza, Alexandre Bernardes; Simmonds, Ian

    2008-12-01

    Transition mechanisms characterizing changes from hurricanes to midlatitude cyclones and vice-versa (extratropical and tropical transition) have become a topic of increasing interest, partially because of their association with recent unusual storms that have developed in different ocean basins of both hemispheres. The aim of this work is to discuss some recent cases of transition and highly unusual hurricane developments and to address some of their wider implications for climate science. Frequently those dramatic cyclones are responsible for severe weather, potentially causing significant damage to property and infrastructure. An additional manifestation discussed here is their association with cold surges, a topic that has been very little explored in the literature. In the Southern Hemisphere, the first South Atlantic hurricane, Catarina, developed in March 2004 under very unusual large-scale conditions. That exceptional cyclone is viewed as a case of tropical transition facilitated by a well-developed blocking structure. A new index for monitoring tropical transition in the subtropical South Atlantic is discussed. This "South Atlantic index" is used to show that the unusual flow during and prior to Catarina's genesis can be attributed to tropical/extratropical interaction mechanisms. The "Donald Duck" case in Australia and Vince in the North Atlantic have also been examined and shown to belong to a category of hybrid-transitioning systems that will achieve at least partial tropical transition. While clearly more research is needed on the topic of transition, as we gain further insight, it is becoming increasingly apparent that features of large-scale circulation do play a fundamental role. A complex interaction between an extratropical transition case and an extreme summer cold surge affecting southeastern Australia is discussed as an example of wider climate implications. PMID:19076416

  3. The recent extreme hydrological events in the Western Amazon Basin: The role of the Pacific and Atlantic Oceans

    Science.gov (United States)

    Espinoza, J.; Ronchail, J.; Guyot, J.; Santini, W.; Lavado, W.; Ore-Hybam Observatory

    2013-05-01

    The Peruvian Amazonas River, the main western tributary of the Amazon basin, has a huge drainage (750 000 km2, 50% of which lies in the Andes) and a mean discharge estimated in 32 000 m3/s, which correspond to 15% of the Amazon discharge at the estuary. Recently, in a context of significant discharge diminution during the low-water season (1970-2012), severe hydrological events, as intense droughts and floods, have been reported in the Peruvian Amazonas River. As they have not been always observed in other regions of the Amazon basin and because they have strong impacts on vulnerable riverside residents, we shall focus on the origin and the predictability of the western Amazon extremes, providing a review of the main findings about the climate features during recent extreme hydrological events in western Amazon. While the lowest discharge value was observed in September 2010 (8 300 m3/s) at the hydrological Tamshiyacu station (near to Iquitos city), a rapid transition toward a high discharge was noticed in April 2011 (45 000 m3/s). Finally, in April 2012, during the on going high waters period, the Amazonas River is experimenting its historical highest discharge (55 000 m3/s). Our work is based on several datasets including in-situ discharge and rainfall information from ORE-HYBAM observatory. Extreme droughts (1995, 2005 and 2010) are generally associated with positive SST anomalies in the tropical North Atlantic and weak trade winds and water vapor transport toward the western Amazon, which, in association with increased subsidence over central and southern Amazon, explain the lack of rainfall and very low discharge values. But, in 1998, toward the end of the 1997-98 El Niño event, the drought has been more likely related to an anomalous divergence of water vapor in the western Amazon that is characteristic of a warm event in the Pacific. The years with a rapid transition form low waters to very high floods (e.g. September 2010 to April 2011) are characterized

  4. Ecological Response to Extreme Flow Events in Streams and Rivers: Implications of Climate Change for Aquatic Biodiversity

    Science.gov (United States)

    Hawkins, C. P.; Vander Laan, J. J.; Dhungel, S.; Tarboton, D. G.

    2014-12-01

    We used the USEPA's 2008-2009 National Rivers and Streams Assessment (NRSA) data to assess the potential sensitivity of stream biodiversity to both spatial variation in measures of extreme flow and likely changes in extreme flows associated with projected climate change. The NRSA data consisted of macroinvertebrate samples collected at 1313 reference-quality sites. We characterized the hydrologic regimes at each of these sites by developing Random Forest empirical models from long-term (≥ 20 years) daily flow records obtained from 601 gaged USGS stations. These models described spatial variation in 16 flow variables as a function of climate and watershed attributes. Three of the models characterized aspects of extreme flow: the mean number of zero-flow events per year (ZeroDays), the mean number of high-flow events per year (HighDays = number of events per year that exceed the 95th percentile of mean annual flow), and the coefficient of variation of daily flows (CV). We used these models to predict the flow attributes expected at each of the 1313 sites with ecological data. We then built additional Random Forest models that related among-site differences in stream macroinvertebrate taxonomic composition, assemblage richness, and the likelihood of observing individual taxa to the 16 measures of flow regime and other environmental predictors. At the national level, ZeroDays was an important predictor of macroinvertebrate biodiversity: richness declined as ZeroDays increased. A similar pattern was observed when analyses were restricted to lowland and plains streams. For eastern highland streams, HighDays was a better predictor of stream biodiversity than aspects of low flow: richness declined as HighDays increased. For western streams, CV was a better predictor of biodiversity than either ZeroDays or HighDays: biodiversity decreased as CV increased. Empirical models that linked flow attributes to climate change projections imply that flow regime response to climate

  5. Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

    Science.gov (United States)

    van Kempen, Monique M L; Smolders, Alfons J P; Lamers, Leon P M; Roelofs, Jan G M

    2012-01-01

    In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval. PMID:23166833

  6. Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

    Directory of Open Access Journals (Sweden)

    Monique M L van Kempen

    Full Text Available In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval.

  7. PS1-10jh - a tidal disruption event with an extremely low disk temperature

    CERN Document Server

    Armijo, Matias Montesinos

    2012-01-01

    The cooler than expected optical-UV transient PS1-10jh detected by the Pan-STARRS1 survey is probably related to a tidal disruption event in which a He-rich stellar core remnant is implied. The evolution of bound debris during the disk phase is studi