WorldWideScience

Sample records for extreme hydrological events

  1. Evaluation of climate change impact on extreme hydrological event ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Changes in hydrological extremes will have implications on the design of future hydraulic structures, flood plain development, and water resource management. This study assesses the potential impact of climate change on extreme hydrological events in the Akaki River catchment area in and around Addis Ababa city.

  2. 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......). In the case of ML estimation, the PDS model provides the most efficient T-year event estimator. In the cases of MOM and PWM estimation, the PDS model is generally preferable for negative shape parameters, whereas the AMS model yields the most efficient estimator for positive shape parameters. A comparison...... of the considered methods reveals that in general, one should use the PDS model with MOM estimation for negative shape parameters, the PDS model with exponentially distributed exceedances if the shape parameter is close to zero, the AMS model with MOM estimation for moderately positive shape parameters, and the PDS...

  3. Dendroclimate evidence for extreme hydrologic events over the late Holocene in the Northeastern United States

    Science.gov (United States)

    Pearl, J. K.; Anchukaitis, K. J.; Pederson, N.; Donnelly, J. P.

    2017-12-01

    Extreme hydrologic events pose a present and future threat to cities and infrastructure in the densely populated coastal corridor of the northeastern United States (NE). An understanding of the potential range and return interval of storms, floods, and droughts is important for improving coastal management and hazard planning, as well as the detection and attribution of trends in regional climate phenomena. Here, we examine a suite of evidence for Common Era paleohydroclimate extreme events in the NE. Our study analyzes a network of hydroclimate sensitive trees, subfossil 'drowned' forests and co-located sediment records, using both classical and isotope dendrochronology, radiocarbon analyses, and sediment stratigraphy. Atlantic White cedar (AWC) forests grow along the NE coast and are exposed to severe coastal weather, as they are typically most successful in near-shore, glacially formed depressions. Many coastal AWC sites are ombrotrophic and contain a precipitation or drought signal in their ring widths. Sub-fossil AWC forests are found where near-shore swamps were drowned and exposed to the ocean. Additionally, the rings of coastal AWC may contain the geochemical signature of landfalling tropical cyclones, which bring with them a large influx of precipitation with distinct oxygen isotopes, which can be used to identify these large storms. Dendrochronology, radiocarbon dating, and analysis of sediment cores are used here to identify and date the occurrence of large overwash events along the coastline of the northeastern United States associated with extreme storms.

  4. Climate Change and Hydrological Extreme Events - Risks and Perspectives for Water Management in Bavaria and Québec

    Science.gov (United States)

    Ludwig, R.

    2017-12-01

    There is as yet no confirmed knowledge whether and how climate change contributes to the magnitude and frequency of hydrological extreme events and how regional water management could adapt to the corresponding risks. The ClimEx project (2015-2019) investigates the effects of climate change on the meteorological and hydrological extreme events and their implications for water management in Bavaria and Québec. High Performance Computing is employed to enable the complex simulations in a hydro-climatological model processing chain, resulting in a unique high-resolution and transient (1950-2100) dataset of climatological and meteorological forcing and hydrological response: (1) The climate module has developed a large ensemble of high resolution data (12km) of the CRCM5 RCM for Central Europe and North-Eastern North America, downscaled from 50 members of the CanESM2 GCM. The dataset is complemented by all available data from the Euro-CORDEX project to account for the assessment of both natural climate variability and climate change. The large ensemble with several thousand model years provides the potential to catch rare extreme events and thus improves the process understanding of extreme events with return periods of 1000+ years. (2) The hydrology module comprises process-based and spatially explicit model setups (e.g. WaSiM) for all major catchments in Bavaria and Southern Québec in high temporal (3h) and spatial (500m) resolution. The simulations form the basis for in depth analysis of hydrological extreme events based on the inputs from the large climate model dataset. The specific data situation enables to establish a new method for `virtual perfect prediction', which assesses climate change impacts on flood risk and water resources management by identifying patterns in the data which reveal preferential triggers of hydrological extreme events. The presentation will highlight first results from the analysis of the large scale ClimEx model ensemble, showing the

  5. The influence of hydrologic residence time on lake carbon cycling dynamics following extreme precipitation events

    Science.gov (United States)

    Jacob A. Zwart; Stephen D. Sebestyen; Christopher T. Solomon; Stuart E. Jones

    2016-01-01

    The frequency and magnitude of extreme events are expected to increase in the future, yet little is known about effects of such events on ecosystem structure and function. We examined how extreme precipitation events affect exports of terrestrial dissolved organic carbon (t-DOC) from watersheds to lakes as well as in-lake heterotrophy in three north-temperate lakes....

  6. Extreme hydrological events and the influence of reservoirs in a highly regulated river basin of northeastern Spain

    Directory of Open Access Journals (Sweden)

    S.M. Vicente-Serrano

    2017-08-01

    New hydrological insights: Results reveal a general reduction in the occurrence of extreme precipitation events in the Segre basin from 1950 to 2013, which corresponded to a general reduction in high flows measured at various gauged stations across the basin. While this study demonstrates spatial differences in the decrease of streamflow between the headwaters and the lower parts of the basin, mainly associated with changes in river regulation, there was no reduction in the frequency of the extraordinary floods. Changes in water management practices in the basin have significantly impacted the frequency, duration, and severity of hydrological droughts downstream of the main dams, as a consequence of the intense water regulation to meet water demands for irrigation and livestock farms. Nonetheless, the hydrological response of the headwaters to these droughts differed markedly from that of the lower areas of the basin.

  7. Forest operations, extreme flooding events, and considerations for hydrologic modeling in the Appalachians--A review

    Science.gov (United States)

    M.A. Eisenbies; W.M. Aust; J.A. Burger; M.B. Adams

    2007-01-01

    The connection between forests and water resources is well established, but the relationships among controlling factors are only partly understood. Concern over the effects of forestry operations, particularly harvesting, on extreme flooding events is a recurrent issue in forest and watershed management. Due to the complexity of the system, and the cost of installing...

  8. ClimEx - Climate change and hydrological extreme events - risks and perspectives for water management in Bavaria and Québec

    Science.gov (United States)

    Ludwig, Ralf; Baese, Frank; Braun, Marco; Brietzke, Gilbert; Brissette, Francois; Frigon, Anne; Giguère, Michel; Komischke, Holger; Kranzlmueller, Dieter; Leduc, Martin; Martel, Jean-Luc; Ricard, Simon; Schmid, Josef; von Trentini, Fabian; Turcotte, Richard; Weismueller, Jens; Willkofer, Florian; Wood, Raul

    2017-04-01

    The recent accumulation of extreme hydrological events in Bavaria and Québec has stimulated scientific and also societal interest. In addition to the challenges of an improved prediction of such situations and the implications for the associated risk management, there is, as yet, no confirmed knowledge whether and how climate change contributes to the magnitude and frequency of hydrological extreme events and how regional water management could adapt to the corresponding risks. The ClimEx project (2015-2019) investigates the effects of climate change on the meteorological and hydrological extreme events and their implications for water management in Bavaria and Québec. High Performance Computing is employed to enable the complex simulations in a hydro-climatological model processing chain, resulting in a unique high-resolution and transient (1950-2100) dataset of climatological and meteorological forcing and hydrological response: (1) The climate module has developed a large ensemble of high resolution data (12km) of the CRCM5 RCM for Central Europe and North-Eastern North America, downscaled from 50 members of the CanESM2 GCM. The dataset is complemented by all available data from the Euro-CORDEX project to account for the assessment of both natural climate variability and climate change. The large ensemble with several thousand model years provides the potential to catch rare extreme events and thus improves the process understanding of extreme events with return periods of 1000+ years. (2) The hydrology module comprises process-based and spatially explicit model setups (e.g. WaSiM) for all major catchments in Bavaria and Southern Québec in high temporal (3h) and spatial (500m) resolution. The simulations form the basis for in depth analysis of hydrological extreme events based on the inputs from the large climate model dataset. The specific data situation enables to establish a new method for 'virtual perfect prediction', which assesses climate change impacts

  9. A climate-based multivariate extreme emulator of met-ocean-hydrological events for coastal flooding

    Science.gov (United States)

    Camus, Paula; Rueda, Ana; Mendez, Fernando J.; Tomas, Antonio; Del Jesus, Manuel; Losada, Iñigo J.

    2015-04-01

    Atmosphere-ocean general circulation models (AOGCMs) are useful to analyze large-scale climate variability (long-term historical periods, future climate projections). However, applications such as coastal flood modeling require climate information at finer scale. Besides, flooding events depend on multiple climate conditions: waves, surge levels from the open-ocean and river discharge caused by precipitation. Therefore, a multivariate statistical downscaling approach is adopted to reproduce relationships between variables and due to its low computational cost. The proposed method can be considered as a hybrid approach which combines a probabilistic weather type downscaling model with a stochastic weather generator component. Predictand distributions are reproduced modeling the relationship with AOGCM predictors based on a physical division in weather types (Camus et al., 2012). The multivariate dependence structure of the predictand (extreme events) is introduced linking the independent marginal distributions of the variables by a probabilistic copula regression (Ben Ayala et al., 2014). This hybrid approach is applied for the downscaling of AOGCM data to daily precipitation and maximum significant wave height and storm-surge in different locations along the Spanish coast. Reanalysis data is used to assess the proposed method. A commonly predictor for the three variables involved is classified using a regression-guided clustering algorithm. The most appropriate statistical model (general extreme value distribution, pareto distribution) for daily conditions is fitted. Stochastic simulation of the present climate is performed obtaining the set of hydraulic boundary conditions needed for high resolution coastal flood modeling. References: Camus, P., Menéndez, M., Méndez, F.J., Izaguirre, C., Espejo, A., Cánovas, V., Pérez, J., Rueda, A., Losada, I.J., Medina, R. (2014b). A weather-type statistical downscaling framework for ocean wave climate. Journal of

  10. Holocene extreme hydrological events and their climatic implications: evidence from the middle Satluj valley, western Himalaya, India

    Science.gov (United States)

    Sharma, Shubhra; Shukla, Anil; Marh, Bhupinder; Bartarya, Sukesh; Juyal, Navin

    2016-04-01

    Extreme hydrological events and associated climatic processes are investigated and inferred through palaeoflood deposits preserved in the middle Satluj valley, India. Satluj River is the largest tributary of the Indus River having third largest catchment area in the Himalaya. Both Indian summer monsoon (ISM) and the mid-latitude westerlies contribute to the hydrological budget of the river. The steep southern orographic front prevents the northward penetration of ISM, while the mid-latitude westerlies bring moisture in form of winter snow to the orogenic interiors. It has been observed that the floods in the Himalaya are intimately associated with the variability in the above climate systems. The optical chronology indicates that floods were clustered around three time domains. The oldest flood phase-1 is dated to ˜14-12 ka which climatically occurred during the initiation of the ISM after the Last Glacial Maximum. The second phase-2 is dated between 8-5 ka and is attributed to the moderate ISM. Whereas, the youngest phase-3 is assigned the Little Ice Age (LIA) and were associated with the variability in the mid-latitude westerlies. Geochemical analyses suggest that floods were generated in higher Himalayan crystalline (HHC) zone, as the extreme precipitation destabilised the precipitous slopes creating Landslide induced Lake Outbursts Floods (LLOFs). Further, the average interval between floods has decreased since 14 ka from 500 years, to 250 years and 100 years during respective flood phases. The southern slopes of Himalaya are influenced by both the monsoon and mid-latitude westerlies and any abrupt changes in the circulation pattern were found to associate with heavy rainfall events in this region. Although an interaction between the westerlies and the monsoon is implicated for extreme floods in the western Himalaya. However, exact mechanism of these interactions is still illusive except for the observational based studies which state that extreme floods

  11. Multivariate hydrological frequency analysis for extreme events using Archimedean copula. Case study: Lower Tunjuelo River basin (Colombia)

    Science.gov (United States)

    Gómez, Wilmar

    2017-04-01

    By analyzing the spatial and temporal variability of extreme precipitation events we can prevent or reduce the threat and risk. Many water resources projects require joint probability distributions of random variables such as precipitation intensity and duration, which can not be independent with each other. The problem of defining a probability model for observations of several dependent variables is greatly simplified by the joint distribution in terms of their marginal by taking copulas. This document presents a general framework set frequency analysis bivariate and multivariate using Archimedean copulas for extreme events of hydroclimatological nature such as severe storms. This analysis was conducted in the lower Tunjuelo River basin in Colombia for precipitation events. The results obtained show that for a joint study of the intensity-duration-frequency, IDF curves can be obtained through copulas and thus establish more accurate and reliable information from design storms and associated risks. It shows how the use of copulas greatly simplifies the study of multivariate distributions that introduce the concept of joint return period used to represent the needs of hydrological designs properly in frequency analysis.

  12. 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

  13. The New York City Operations Support Tool: Supporting Water Supply Operations for Millions in an Era of Changing Patterns in Hydrological Extreme Events

    Science.gov (United States)

    Matonse, A. H.; Porter, J. H.; Frei, A.

    2015-12-01

    Providing an average 1.1 billion gallons (~ 4.2 x 106 cubic meters) of drinking water per day to approximately nine million people in New York City (NYC) and four upstate counties, the NYC water supply is among the world's largest unfiltered systems. In addition to providing a reliable water supply in terms of water quantity and quality, the city has to fulfill other flow objectives to serve downstream communities. At times, such as during extreme hydrological events, water quality issues may restrict water usage for parts of the system. To support a risk-based water supply decision making process NYC has developed the Operations Support Tool (OST). OST combines a water supply systems model with reservoir water quality models, near real time data ingestion, data base management and an ensemble hydrological forecast. A number of reports have addressed the frequency and intensities of extreme hydrological events across the continental US. In the northeastern US studies have indicated an increase in the frequency of extremely large precipitation and streamflow events during the most recent decades. During this presentation we describe OST and, using case studies we demonstrate how this tool has been useful to support operational decisions. We also want to motivate a discussion about how undergoing changes in patterns of hydrological extreme events elevate the challenge faced by water supply managers and the role of the scientific community to integrate nonstationarity approaches in hydrologic forecast and modeling.

  14. Evaluation of uncertainty in capturing the spatial variability and magnitudes of extreme hydrological events for the uMngeni catchment, South Africa

    Science.gov (United States)

    Kusangaya, Samuel; Warburton Toucher, Michele L.; van Garderen, Emma Archer

    2018-02-01

    Downscaled General Circulation Models (GCMs) output are used to forecast climate change and provide information used as input for hydrological modelling. Given that our understanding of climate change points towards an increasing frequency, timing and intensity of extreme hydrological events, there is therefore the need to assess the ability of downscaled GCMs to capture these extreme hydrological events. Extreme hydrological events play a significant role in regulating the structure and function of rivers and associated ecosystems. In this study, the Indicators of Hydrologic Alteration (IHA) method was adapted to assess the ability of simulated streamflow (using downscaled GCMs (dGCMs)) in capturing extreme river dynamics (high and low flows), as compared to streamflow simulated using historical climate data from 1960 to 2000. The ACRU hydrological model was used for simulating streamflow for the 13 water management units of the uMngeni Catchment, South Africa. Statistically downscaled climate models obtained from the Climate System Analysis Group at the University of Cape Town were used as input for the ACRU Model. Results indicated that, high flows and extreme high flows (one in ten year high flows/large flood events) were poorly represented both in terms of timing, frequency and magnitude. Simulated streamflow using dGCMs data also captures more low flows and extreme low flows (one in ten year lowest flows) than that captured in streamflow simulated using historical climate data. The overall conclusion was that although dGCMs output can reasonably be used to simulate overall streamflow, it performs poorly when simulating extreme high and low flows. Streamflow simulation from dGCMs must thus be used with caution in hydrological applications, particularly for design hydrology, as extreme high and low flows are still poorly represented. This, arguably calls for the further improvement of downscaling techniques in order to generate climate data more relevant and

  15. A Projection of the Effects of the Climate Change Induced by Increased CO2 on Extreme Hydrologic Events in the Western U.S

    International Nuclear Information System (INIS)

    Kim, Jinwon

    2005-01-01

    The effects of increased atmospheric CO2 on the frequency of extreme hydrologic events in the Western United States (WUS) for the 10-yr period of 2040-2049 are examined using dynamically downscaled regional climate change signals. For assessing the changes in the occurrence of hydrologic extremes, downscaled climate change signals in daily precipitation and runoff that are likely to indicate the occurrence of extreme events are examined. Downscaled climate change signals in the selected indicators suggest that the global warming induced by increased CO2 is likely to increase extreme hydrologic events in the WUS. The indicators for heavy precipitation events show largest increases in the mountainous regions of the northern California Coastal Range and the Sierra Nevada. Increased cold season precipitation and increased rainfall-portion of precipitation at the expense of snowfall in the projected warmer climate result in large increases in high runoff events in the Sierra Nevada river basins that are already prone to cold season flooding in todays climate. The projected changes in the hydrologic characteristics in the WUS are mainly associated with higher freezing levels in the warmer climate and increases in the cold season water vapor influx from the Pacific Ocean

  16. Testing a distributed hydrological model to predict scenarios of extreme events on a marginal olive orchard microcatchment

    Science.gov (United States)

    Guzmán, Enrique; Aguilar, Cristina; Taguas, Encarnación V.

    2014-05-01

    Olive groves constitute a traditional Mediterranean crop and thus, an important source of income to these regions and a crucial landscape component. Despite its importance, most of the olive groves in the region of Andalusia, Southern Spain, are located in sloping areas, which implies a significant risk of erosion. The combination of data and models allow enhancing the knowledge about processes taking place in these areas as well as the prediction of future scenarios. This aspect might be essential to plan soil protection strategies within a context of climate change where the IPCC estimates a significant increase of soil aridity and torrential events by the end of the century. The objective of this study is to estimate the rainfall-runoff-sediment dynamics in a microcatchment olive grove with the aid of a physically-based distributed hydrological model in order to evaluate the effect of extreme events on runoff and erosion. This study will allow to improve land-use and management planning activities in similar areas. In addition, the scale of the study (microcatchment) will allow to contrast the results in larger areas such as catchment regional spatial scales.

  17. A retrospective streamflow ensemble forecast for an extreme hydrologic event: a case study of Hurricane Irene and on the Hudson River basin

    Science.gov (United States)

    Saleh, Firas; Ramaswamy, Venkatsundar; Georgas, Nickitas; Blumberg, Alan F.; Pullen, Julie

    2016-07-01

    This paper investigates the uncertainties in hourly streamflow ensemble forecasts for an extreme hydrological event using a hydrological model forced with short-range ensemble weather prediction models. A state-of-the art, automated, short-term hydrologic prediction framework was implemented using GIS and a regional scale hydrological model (HEC-HMS). The hydrologic framework was applied to the Hudson River basin ( ˜ 36 000 km2) in the United States using gridded precipitation data from the National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) and was validated against streamflow observations from the United States Geologic Survey (USGS). Finally, 21 precipitation ensemble members of the latest Global Ensemble Forecast System (GEFS/R) were forced into HEC-HMS to generate a retrospective streamflow ensemble forecast for an extreme hydrological event, Hurricane Irene. The work shows that ensemble stream discharge forecasts provide improved predictions and useful information about associated uncertainties, thus improving the assessment of risks when compared with deterministic forecasts. The uncertainties in weather inputs may result in false warnings and missed river flooding events, reducing the potential to effectively mitigate flood damage. The findings demonstrate how errors in the ensemble median streamflow forecast and time of peak, as well as the ensemble spread (uncertainty) are reduced 48 h pre-event by utilizing the ensemble framework. The methodology and implications of this work benefit efforts of short-term streamflow forecasts at regional scales, notably regarding the peak timing of an extreme hydrologic event when combined with a flood threshold exceedance diagram. Although the modeling framework was implemented on the Hudson River basin, it is flexible and applicable in other parts of the world where atmospheric reanalysis products and streamflow data are available.

  18. Recent hydrological variability and extreme precipitation events in Moroccan Middle-Atlas mountains: micro-scale analyses of lacustrine sediments

    Science.gov (United States)

    Jouve, Guillaume; Vidal, Laurence; Adallal, Rachid; Bard, Edouard; Benkaddour, Abdel; Chapron, Emmanuel; Courp, Thierry; Dezileau, Laurent; Hébert, Bertil; Rhoujjati, Ali; Simonneau, Anaelle; Sonzogni, Corinne; Sylvestre, Florence; Tachikawa, Kazuyo; Viry, Elisabeth

    2016-04-01

    Since the 1990s, the Mediterranean basin undergoes an increase in precipitation events and extreme droughts likely to intensify in the XXI century, and whose origin is attributable to human activities since 1850 (IPCC, 2013). Regional climate models indicate a strengthening of flood episodes at the end of the XXI century in Morocco (Tramblay et al, 2012). To understand recent hydrological and paleohydrological variability in North Africa, our study focuses on the macro- and micro-scale analysis of sedimentary sequences from Lake Azigza (Moroccan Middle Atlas Mountains) covering the last few centuries. This lake is relevant since local site monitoring revealed that lake water table levels were correlated with precipitation regime (Adallal R., PhD Thesis in progress). The aim of our study is to distinguish sedimentary facies characteristic of low and high lake levels, in order to reconstruct past dry and wet periods during the last two hundred years. Here, we present results from sedimentological (lithology, grain size, microstructures under thin sections), geochemical (XRF) and physical (radiography) analyses on short sedimentary cores (64 cm long) taken into the deep basin of Lake Azigza (30 meters water depth). Cores have been dated (radionuclides 210Pb, 137Cs, and 14C dating). Two main facies were distinguished: one organic-rich facies composed of wood fragments, several reworked layers and characterized by Mn peaks; and a second facies composed of terrigenous clastic sediments, without wood nor reworked layers, and characterized by Fe, Ti, Si and K peaks. The first facies is interpreted as a high lake level stand. Indeed, the highest paleoshoreline is close to the vegetation, and steeper banks can increase the current velocity, allowing the transport of wood fragments in case of extreme precipitation events. Mn peaks are interpreted as Mn oxides precipitations under well-oxygenated deep waters after runoff events. The second facies is linked to periods of

  19. Analysis of extreme events

    CSIR Research Space (South Africa)

    Khuluse, S

    2009-04-01

    Full Text Available ) determination of the distribution of the damage and (iii) preparation of products that enable prediction of future risk events. The methodology provided by extreme value theory can also be a powerful tool in risk analysis...

  20. Improving predictions of the effects of extreme events, land use, and climate change on the hydrology of watersheds in the Philippines

    Directory of Open Access Journals (Sweden)

    R. Benavidez

    2016-05-01

    Full Text Available Due to its location within the typhoon belt, the Philippines is vulnerable to tropical cyclones that can cause destructive floods. Climate change is likely to exacerbate these risks through increases in tropical cyclone frequency and intensity. To protect populations and infrastructure, disaster risk management in the Philippines focuses on real-time flood forecasting and structural measures such as dikes and retaining walls. Real-time flood forecasting in the Philippines mostly utilises two models from the Hydrologic Engineering Center (HEC: the Hydrologic Modeling System (HMS for watershed modelling, and the River Analysis System (RAS for inundation modelling. This research focuses on using non-structural measures for flood mitigation, such as changing land use management or watershed rehabilitation. This is being done by parameterising and applying the Land Utilisation and Capability Indicator (LUCI model to the Cagayan de Oro watershed (1400 km2 in southern Philippines. The LUCI model is capable of identifying areas providing ecosystem services such as flood mitigation and agricultural productivity, and analysing trade-offs between services. It can also assess whether management interventions could enhance or degrade ecosystem services at fine spatial scales. The LUCI model was used to identify areas within the watershed that are providing flood mitigating services and areas that would benefit from management interventions. For the preliminary comparison, LUCI and HEC-HMS were run under the same scenario: baseline land use and the extreme rainfall event of Typhoon Bopha. The hydrographs from both models were then input to HEC-RAS to produce inundation maps. The novelty of this research is two-fold: (1 this type of ecosystem service modelling has not been carried out in the Cagayan de Oro watershed; and (2 this is the first application of the LUCI model in the Philippines. Since this research is still ongoing, the results presented in

  1. Improving predictions of the effects of extreme events, land use, and climate change on the hydrology of watersheds in the Philippines

    Science.gov (United States)

    Benavidez, Rubianca; Jackson, Bethanna; Maxwell, Deborah; Paringit, Enrico

    2016-05-01

    Due to its location within the typhoon belt, the Philippines is vulnerable to tropical cyclones that can cause destructive floods. Climate change is likely to exacerbate these risks through increases in tropical cyclone frequency and intensity. To protect populations and infrastructure, disaster risk management in the Philippines focuses on real-time flood forecasting and structural measures such as dikes and retaining walls. Real-time flood forecasting in the Philippines mostly utilises two models from the Hydrologic Engineering Center (HEC): the Hydrologic Modeling System (HMS) for watershed modelling, and the River Analysis System (RAS) for inundation modelling. This research focuses on using non-structural measures for flood mitigation, such as changing land use management or watershed rehabilitation. This is being done by parameterising and applying the Land Utilisation and Capability Indicator (LUCI) model to the Cagayan de Oro watershed (1400 km2) in southern Philippines. The LUCI model is capable of identifying areas providing ecosystem services such as flood mitigation and agricultural productivity, and analysing trade-offs between services. It can also assess whether management interventions could enhance or degrade ecosystem services at fine spatial scales. The LUCI model was used to identify areas within the watershed that are providing flood mitigating services and areas that would benefit from management interventions. For the preliminary comparison, LUCI and HEC-HMS were run under the same scenario: baseline land use and the extreme rainfall event of Typhoon Bopha. The hydrographs from both models were then input to HEC-RAS to produce inundation maps. The novelty of this research is two-fold: (1) this type of ecosystem service modelling has not been carried out in the Cagayan de Oro watershed; and (2) this is the first application of the LUCI model in the Philippines. Since this research is still ongoing, the results presented in this paper are

  2. Extreme Energy Events Monitoring report

    CERN Document Server

    Baimukhamedova, Nigina

    2015-01-01

    Following paper reflects the progress I made on Summer Student Program within Extreme Energy Events Monitor project I was working on. During 8 week period I managed to build a simple detector system that is capable of triggering events similar to explosions (sudden change in sound levels) and measuring approximate location of the event. Source codes are available upon request and settings described further.

  3. Evolution caused by extreme events.

    Science.gov (United States)

    Grant, Peter R; Grant, B Rosemary; Huey, Raymond B; Johnson, Marc T J; Knoll, Andrew H; Schmitt, Johanna

    2017-06-19

    Extreme events can be a major driver of evolutionary change over geological and contemporary timescales. Outstanding examples are evolutionary diversification following mass extinctions caused by extreme volcanism or asteroid impact. The evolution of organisms in contemporary time is typically viewed as a gradual and incremental process that results from genetic change, environmental perturbation or both. However, contemporary environments occasionally experience strong perturbations such as heat waves, floods, hurricanes, droughts and pest outbreaks. These extreme events set up strong selection pressures on organisms, and are small-scale analogues of the dramatic changes documented in the fossil record. Because extreme events are rare, almost by definition, they are difficult to study. So far most attention has been given to their ecological rather than to their evolutionary consequences. We review several case studies of contemporary evolution in response to two types of extreme environmental perturbations, episodic (pulse) or prolonged (press). Evolution is most likely to occur when extreme events alter community composition. We encourage investigators to be prepared for evolutionary change in response to rare events during long-term field studies.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'. © 2017 The Author(s).

  4. Hydrologic extremes - an intercomparison of multiple gridded statistical downscaling methods

    Science.gov (United States)

    Werner, Arelia T.; Cannon, Alex J.

    2016-04-01

    Gridded statistical downscaling methods are the main means of preparing climate model data to drive distributed hydrological models. Past work on the validation of climate downscaling methods has focused on temperature and precipitation, with less attention paid to the ultimate outputs from hydrological models. Also, as attention shifts towards projections of extreme events, downscaling comparisons now commonly assess methods in terms of climate extremes, but hydrologic extremes are less well explored. Here, we test the ability of gridded downscaling models to replicate historical properties of climate and hydrologic extremes, as measured in terms of temporal sequencing (i.e. correlation tests) and distributional properties (i.e. tests for equality of probability distributions). Outputs from seven downscaling methods - bias correction constructed analogues (BCCA), double BCCA (DBCCA), BCCA with quantile mapping reordering (BCCAQ), bias correction spatial disaggregation (BCSD), BCSD using minimum/maximum temperature (BCSDX), the climate imprint delta method (CI), and bias corrected CI (BCCI) - are used to drive the Variable Infiltration Capacity (VIC) model over the snow-dominated Peace River basin, British Columbia. Outputs are tested using split-sample validation on 26 climate extremes indices (ClimDEX) and two hydrologic extremes indices (3-day peak flow and 7-day peak flow). To characterize observational uncertainty, four atmospheric reanalyses are used as climate model surrogates and two gridded observational data sets are used as downscaling target data. The skill of the downscaling methods generally depended on reanalysis and gridded observational data set. However, CI failed to reproduce the distribution and BCSD and BCSDX the timing of winter 7-day low-flow events, regardless of reanalysis or observational data set. Overall, DBCCA passed the greatest number of tests for the ClimDEX indices, while BCCAQ, which is designed to more accurately resolve event

  5. Multidecadal oscillations in rainfall and hydrological extremes

    Science.gov (United States)

    Willems, Patrick

    2013-04-01

    Many studies have anticipated a worldwide increase in the frequency and intensity of precipitation extremes and floods since the last decade(s). Natural variability by climate oscillations partly determines the observed evolution of precipitation extremes. Based on a technique for the identification and analysis of changes in extreme quantiles, it is shown that hydrological extremes have oscillatory behaviour at multidecadal time scales. Results are based on nearly independent extremes extracted from long-term historical time series of precipitation intensities and river flows. Study regions include Belgium - The Netherlands (Meuse basin), Ethiopia (Blue Nile basin) and Ecuador (Paute basin). For Belgium - The Netherlands, the past 100 years showed larger and more hydrological extremes around the 1910s, 1950-1960s, and more recently during the 1990-2000s. Interestingly, the oscillations for southwestern Europe are anti-correlated with these of northwestern Europe, thus with oscillation highs in the 1930-1940s and 1970s. The precipitation oscillation peaks are explained by persistence in atmospheric circulation patterns over the North Atlantic during periods of 10 to 15 years. References: Ntegeka V., Willems P. (2008), 'Trends and multidecadal oscillations in rainfall extremes, based on a more than 100 years time series of 10 minutes rainfall intensities at Uccle, Belgium', Water Resources Research, 44, W07402, doi:10.1029/2007WR006471 Mora, D., Willems, P. (2012), 'Decadal oscillations in rainfall and air temperature in the Paute River Basin - Southern Andes of Ecuador', Theoretical and Applied Climatology, 108(1), 267-282, doi:0.1007/s00704-011-0527-4 Taye, M.T., Willems, P. (2011). 'Influence of climate variability on representative QDF predictions of the upper Blue Nile Basin', Journal of Hydrology, 411, 355-365, doi:10.1016/j.jhydrol.2011.10.019 Taye, M.T., Willems, P. (2012). 'Temporal variability of hydro-climatic extremes in the Blue Nile basin', Water

  6. Defining Extreme Events: A Cross-Disciplinary Review

    Science.gov (United States)

    McPhillips, Lauren E.; Chang, Heejun; Chester, Mikhail V.; Depietri, Yaella; Friedman, Erin; Grimm, Nancy B.; Kominoski, John S.; McPhearson, Timon; Méndez-Lázaro, Pablo; Rosi, Emma J.; Shafiei Shiva, Javad

    2018-03-01

    Extreme events are of interest worldwide given their potential for substantial impacts on social, ecological, and technical systems. Many climate-related extreme events are increasing in frequency and/or magnitude due to anthropogenic climate change, and there is increased potential for impacts due to the location of urbanization and the expansion of urban centers and infrastructures. Many disciplines are engaged in research and management of these events. However, a lack of coherence exists in what constitutes and defines an extreme event across these fields, which impedes our ability to holistically understand and manage these events. Here, we review 10 years of academic literature and use text analysis to elucidate how six major disciplines—climatology, earth sciences, ecology, engineering, hydrology, and social sciences—define and communicate extreme events. Our results highlight critical disciplinary differences in the language used to communicate extreme events. Additionally, we found a wide range in definitions and thresholds, with more than half of examined papers not providing an explicit definition, and disagreement over whether impacts are included in the definition. We urge distinction between extreme events and their impacts, so that we can better assess when responses to extreme events have actually enhanced resilience. Additionally, we suggest that all researchers and managers of extreme events be more explicit in their definition of such events as well as be more cognizant of how they are communicating extreme events. We believe clearer and more consistent definitions and communication can support transdisciplinary understanding and management of extreme events.

  7. Nutrition security under extreme events

    Science.gov (United States)

    Martinez, A.

    2017-12-01

    Nutrition security under extreme events. Zero hunger being one of the Sustainable Development Goal from the United Nations, food security has become a trending research topic. However extreme events impact on global food security is not yet 100% understood and there is a lack of comprehension of the underlying mechanisms of global food trade and nutrition security to improve countries resilience to extreme events. In a globalized world, food is still a highly regulated commodity and a strategic resource. A drought happening in a net food-exporter will have little to no effect on its own population but the repercussion on net food-importers can be extreme. In this project, we propose a methodology to describe and quantify the impact of a local drought to human health at a global scale. For this purpose, nutrition supply and global trade data from FAOSTAT have been used with domestic food production from national agencies and FAOSTAT, global precipitation from the Climate Research Unit and health data from the World Health Organization. A modified Herfindahl-Hirschman Index (HHI) has been developed to measure the level of resilience of one country to a drought happening in another country. This index describes how a country is dependent of importation and how diverse are its importation. Losses of production and exportation due to extreme events have been calculated using yield data and a simple food balance at country scale. Results show that countries the most affected by global droughts are the one with the highest dependency to one exporting country. Changes induced by droughts also disturbed their domestic proteins, fat and calories supply resulting most of the time in a higher intake of calories or fat over proteins.

  8. Attribution of climate extreme events

    Science.gov (United States)

    Trenberth, Kevin E.; Fasullo, John T.; Shepherd, Theodore G.

    2015-08-01

    There is a tremendous desire to attribute causes to weather and climate events that is often challenging from a physical standpoint. Headlines attributing an event solely to either human-induced climate change or natural variability can be misleading when both are invariably in play. The conventional attribution framework struggles with dynamically driven extremes because of the small signal-to-noise ratios and often uncertain nature of the forced changes. Here, we suggest that a different framing is desirable, which asks why such extremes unfold the way they do. Specifically, we suggest that it is more useful to regard the extreme circulation regime or weather event as being largely unaffected by climate change, and question whether known changes in the climate system's thermodynamic state affected the impact of the particular event. Some examples briefly illustrated include 'snowmaggedon' in February 2010, superstorm Sandy in October 2012 and supertyphoon Haiyan in November 2013, and, in more detail, the Boulder floods of September 2013, all of which were influenced by high sea surface temperatures that had a discernible human component.

  9. On causality of extreme events

    Directory of Open Access Journals (Sweden)

    Massimiliano Zanin

    2016-06-01

    Full Text Available 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 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. We further show how the proposed metric is able to outperform classical causality metrics, provided non-linear relationships are present and large enough data sets are available.

  10. Dynamically adaptive data-driven simulation of extreme hydrological flows

    Science.gov (United States)

    Kumar Jain, Pushkar; Mandli, Kyle; Hoteit, Ibrahim; Knio, Omar; Dawson, Clint

    2018-02-01

    Hydrological hazards such as storm surges, tsunamis, and rainfall-induced flooding are physically complex events that are costly in loss of human life and economic productivity. Many such disasters could be mitigated through improved emergency evacuation in real-time and through the development of resilient infrastructure based on knowledge of how systems respond to extreme events. Data-driven computational modeling is a critical technology underpinning these efforts. This investigation focuses on the novel combination of methodologies in forward simulation and data assimilation. The forward geophysical model utilizes adaptive mesh refinement (AMR), a process by which a computational mesh can adapt in time and space based on the current state of a simulation. The forward solution is combined with ensemble based data assimilation methods, whereby observations from an event are assimilated into the forward simulation to improve the veracity of the solution, or used to invert for uncertain physical parameters. The novelty in our approach is the tight two-way coupling of AMR and ensemble filtering techniques. The technology is tested using actual data from the Chile tsunami event of February 27, 2010. These advances offer the promise of significantly transforming data-driven, real-time modeling of hydrological hazards, with potentially broader applications in other science domains.

  11. Dynamically adaptive data-driven simulation of extreme hydrological flows

    KAUST Repository

    Kumar Jain, Pushkar

    2017-12-27

    Hydrological hazards such as storm surges, tsunamis, and rainfall-induced flooding are physically complex events that are costly in loss of human life and economic productivity. Many such disasters could be mitigated through improved emergency evacuation in real-time and through the development of resilient infrastructure based on knowledge of how systems respond to extreme events. Data-driven computational modeling is a critical technology underpinning these efforts. This investigation focuses on the novel combination of methodologies in forward simulation and data assimilation. The forward geophysical model utilizes adaptive mesh refinement (AMR), a process by which a computational mesh can adapt in time and space based on the current state of a simulation. The forward solution is combined with ensemble based data assimilation methods, whereby observations from an event are assimilated into the forward simulation to improve the veracity of the solution, or used to invert for uncertain physical parameters. The novelty in our approach is the tight two-way coupling of AMR and ensemble filtering techniques. The technology is tested using actual data from the Chile tsunami event of February 27, 2010. These advances offer the promise of significantly transforming data-driven, real-time modeling of hydrological hazards, with potentially broader applications in other science domains.

  12. Análise de eventos hidrológicos extremos, usando-se a distribuição GEV e momentos LH Analysis of extreme hydrological events using GEV distribution and LH moments

    Directory of Open Access Journals (Sweden)

    Manoel M. F. de Queiroz

    2006-06-01

    Full Text Available A distribuição de probabilidade generalizada de valores extremos (GEV, tem facilitado muitas aplicações em hidrologia, utilizada na modelação de eventos extremos naturais. Estudos sobre o assunto mostram que estimadores de máxima verossimilhança dos parâmetros da GEV são instáveis em pequenas amostras, podendo fornecer valores absurdos do parâmetro de forma, quando então são recomendados estimadores de momentos LH, baseados na combinação linear de estatísticas de altas ordens, introduzidas para caracterizar a parte mais alta da distribuição e os valores extremos dos dados; contudo, não se dispõe de programas computacionais para PC, que modelem eventos extremos via momentos LH. Objetivou-se, com este trabalho, apresentar a modelação de eventos hidrológicos extremos através da distribuição GEV, utilizando-se momentos LH para estimar seus parâmetros e o teste estatístico proposto por Wang (1998 para verificação da qualidade dos ajustes desenvolvidos no ambiente Matlab. Como resultados, são apresentados as estimativas dos parâmetros da GEV, os valores das taxas de momentos LH: coeficientes de variação, assimetria e curtose, e os valores do teste de qualidade de ajuste, em aplicações com dados de vazão de rios do Paraná.The generalized extreme-value (GEV distribution has facilitated many applications in hydrology, used to model a wide variety of natural extreme events. Previous studies show that small-sample maximum-likelihood estimators parameters are unstable and demonstrates that absurd values of the GEV shape parameter can be generated. It is recommended that LH moments estimators, based on linear combinations of higher-order statistics, should be introduced for characterizing the upper part of distributions and larger events in data. However, there have been no computer packages for PC that model extreme events by LH moments. The objective of this paper was to present the modeling of hydrological extreme

  13. 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.

  14. Controlling extreme events on complex networks

    Science.gov (United States)

    Chen, Yu-Zhong; Huang, Zi-Gang; Lai, Ying-Cheng

    2014-08-01

    Extreme events, a type of collective behavior in complex networked dynamical systems, often can have catastrophic consequences. To develop effective strategies to control extreme events is of fundamental importance and practical interest. Utilizing transportation dynamics on complex networks as a prototypical setting, we find that making the network ``mobile'' can effectively suppress extreme events. A striking, resonance-like phenomenon is uncovered, where an optimal degree of mobility exists for which the probability of extreme events is minimized. We derive an analytic theory to understand the mechanism of control at a detailed and quantitative level, and validate the theory numerically. Implications of our finding to current areas such as cybersecurity are discussed.

  15. 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.

  16. Characterizing Drought Events from a Hydrological Model Ensemble

    Science.gov (United States)

    Smith, Katie; Parry, Simon; Prudhomme, Christel; Hannaford, Jamie; Tanguy, Maliko; Barker, Lucy; Svensson, Cecilia

    2017-04-01

    Hydrological droughts are a slow onset natural hazard that can affect large areas. Within the United Kingdom there have been eight major drought events over the last 50 years, with several events acting at the continental scale, and covering the entire nation. Many of these events have lasted several years and had significant impacts on agriculture, the environment and the economy. Generally in the UK, due to a northwest-southeast gradient in rainfall and relief, as well as varying underlying geology, droughts tend to be most severe in the southeast, which can threaten water supplies to the capital in London. With the impacts of climate change likely to increase the severity and duration of drought events worldwide, it is crucial that we gain an understanding of the characteristics of some of the longer and more extreme droughts of the 19th and 20th centuries, so we may utilize this information in planning for the future. Hydrological models are essential both for reconstructing such events that predate streamflow records, and for use in drought forecasting. However, whilst the uncertainties involved in modelling hydrological extremes on the flooding end of the flow regime have been studied in depth over the past few decades, the uncertainties in simulating droughts and low flow events have not yet received such rigorous academic attention. The "Cascade of Uncertainty" approach has been applied to explore uncertainty and coherence across simulations of notable drought events from the past 50 years using the airGR family of daily lumped catchment models. Parameter uncertainty has been addressed using a Latin Hypercube sampled experiment of 500,000 parameter sets per model (GR4J, GR5J and GR6J), over more than 200 catchments across the UK. The best performing model parameterisations, determined using a multi-objective function approach, have then been taken forward for use in the assessment of the impact of model parameters and model structure on drought event

  17. Extreme Weather Events and Climate Change Attribution

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Katherine [National Academy of Sciences, Washington, DC (United States)

    2016-03-31

    A report from the National Academies of Sciences, Engineering, and Medicine concludes it is now possible to estimate the influence of climate change on some types of extreme events. The science of extreme event attribution has advanced rapidly in recent years, giving new insight to the ways that human-caused climate change can influence the magnitude or frequency of some extreme weather events. This report examines the current state of science of extreme weather attribution, and identifies ways to move the science forward to improve attribution capabilities. Confidence is strongest in attributing types of extreme events that are influenced by climate change through a well-understood physical mechanism, such as, the more frequent heat waves that are closely connected to human-caused global temperature increases, the report finds. Confidence is lower for other types of events, such as hurricanes, whose relationship to climate change is more complex and less understood at present. For any extreme event, the results of attribution studies hinge on how questions about the event's causes are posed, and on the data, modeling approaches, and statistical tools chosen for the analysis.

  18. SMOS data and extreme events

    Science.gov (United States)

    Kerr, Yann; Wigneron, Jean-Pierre; Ferrazzoli, Paolo; Mahmoodi, Ali; Al-Yaari, Amen; Parrens, Marie; Bitar, Ahmad Al; Rodriguez-Fernandez, Nemesio; Bircher, Simone; Molero-rodenas, Beatriz; Drusch, Matthias; Mecklenburg, Susanne

    2017-04-01

    The SMOS (Soil Moisture and Ocean Salinity) satellite was successfully launched in November 2009. This ESA led mission for Earth Observation is dedicated to provide soil moisture over continental surface (with an accuracy goal of 0.04 m3/m3), vegetation water content over land, and ocean salinity. These geophysical features are important as they control the energy balance between the surface and the atmosphere. Their knowledge at a global scale is of interest for climatic and weather researches, and in particular in improving model forecasts. The Soil Moisture and Ocean Salinity mission has now been collecting data for over 7 years. The whole data set has been reprocessed (Version 620 for levels 1 and 2 and version 3 for level 3 CATDS) while operational near real time soil moisture data is now available and assimilation of SMOS data in NWP has proved successful. After 7 years it seems important to start using data for having a look at anomalies and see how they can relate to large scale events. We have also produced a 15 year soil moisture data set by merging SMOS and AMSR using a neural network approach. The purpose of this communication is to present the mission results after more than seven years in orbit in a climatic trend perspective, as through such a period anomalies can be detected. Thereby we benefit from consistent datasets provided through the latest reprocessing using most recent algorithm enhancements. Using the above mentioned products it is possible to follow large events such as the evolution of the droughts in North America, or water fraction evolution over the Amazonian basin. In this occasion we will focus on the analysis of SMOS and ancillary products anomalies to reveal two climatic trends, the temporal evolution of water storage over the Indian continent in relation to rainfall anomalies, and the global impact of El Nino types of events on the general water storage distribution. This presentation shows in detail the use of long term data sets

  19. Extreme events monitoring from space

    Science.gov (United States)

    Kerr, Yann; Bitar, Ahmad Al; Mahmoodi, Ali; Richaume, Philippe; Al-Yaari, Amen; Wigneron, Jean-Pierre

    2016-04-01

    The SMOS (Soil Moisture and Ocean Salinity) satellite was successfully launched in November 2009. This ESA led mission for Earth Observation is dedicated to provide soil moisture over continental surface (with an accuracy goal of 0.04 m3/m3), vegetation water content over land, and ocean salinity. These geophysical features are important as they control the energy balance between the surface and the atmosphere. Their knowledge at a global scale is of interest for climatic and weather researches, and in particular in improving model forecasts. The Soil Moisture and Ocean Salinity mission has now been collecting data for 6 years. The whole data set has just been reprocessed (Version 620 for levels 1 and 2 and version 3 for level 3 CATDS). After 6 years it seems important to start using data for having a look at anomalies and see how they can relate to large scale events The purpose of this communication is to present the mission results after more than six years in orbit in a climatic trend perspective, as through such a period anomalies can be detected. Thereby we benefit from consistent datasets provided through the latest reprocessing using most recent algorithm enhancements. Using the above mentioned products it is possible to follow large events such as the evolution of the droughts in North America, or water fraction evolution over the Amazonian basin. In this occasion we will focus on the analysis of SMOS and ancillary products anomalies to reveal two climatic trends, the temporal evolution of water storage over the Indian continent in relation to rainfall anomalies, and the global impact of El Nino types of events on the general water storage distribution. This presentation shows in detail the use of long term data sets of L-band microwave radiometry in two specific cases, namely droughts and water budget over a large basin. Several other analyses are under way currently. Obviously, vegetation water content, but also dielectric constant, are carrying a wealth

  20. 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

  1. 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)

  2. Extreme weather and climate events with ecological relevance: a review.

    Science.gov (United States)

    Ummenhofer, Caroline C; Meehl, Gerald A

    2017-06-19

    Robust evidence exists that certain extreme weather and climate events, especially daily temperature and precipitation extremes, have changed in regard to intensity and frequency over recent decades. These changes have been linked to human-induced climate change, while the degree to which climate change impacts an individual extreme climate event (ECE) is more difficult to quantify. Rapid progress in event attribution has recently been made through improved understanding of observed and simulated climate variability, methods for event attribution and advances in numerical modelling. Attribution for extreme temperature events is stronger compared with other event types, notably those related to the hydrological cycle. Recent advances in the understanding of ECEs, both in observations and their representation in state-of-the-art climate models, open new opportunities for assessing their effect on human and natural systems. Improved spatial resolution in global climate models and advances in statistical and dynamical downscaling now provide climatic information at appropriate spatial and temporal scales. Together with the continued development of Earth System Models that simulate biogeochemical cycles and interactions with the biosphere at increasing complexity, these make it possible to develop a mechanistic understanding of how ECEs affect biological processes, ecosystem functioning and adaptation capabilities. Limitations in the observational network, both for physical climate system parameters and even more so for long-term ecological monitoring, have hampered progress in understanding bio-physical interactions across a range of scales. New opportunities for assessing how ECEs modulate ecosystem structure and functioning arise from better scientific understanding of ECEs coupled with technological advances in observing systems and instrumentation.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events

  3. Climate change and extreme events in weather

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.

    reported that the climate based extreme weather event is increasing throughout the world. One of the major chal- lenges before the scientists is to determine whether the ob- served change in extreme weather events exceeds the vari- ability expected through... was recorded in July 1943 on the hills of Mewar and Merwara. Unprecedent flood in Ajmer and Merwara devasted 50 villages and took a toll of 5000 lives (De et al., 2005). Severe Floods occurred to Godavari and Tungabhadra rivers in the last week of August...

  4. Hydrologic Extremes and Risk Assessment under Non-stationarity

    Science.gov (United States)

    Mondal, A.

    2015-12-01

    In the context of hydrologic designs, robust assessment and communication of risk is crucial to ascertain a sustainable water future. Traditional methods for defining return period, risk or reliability assumes a stationary regime which may no longer be valid because of natural or man-made changes. Reformulations are suggested in recent literature to account for non-stationarity in the definition of hydrologic risk, as time evolves. This study presents a comparative analysis of design levels under non-stationarity based on time varying annual exceedance probabilities, waiting time of a hazardous event, number of hazardous events and probability of failure. A case study application is shown for peak streamflow in the flood-prone delta area of the Krishna River in India where an increasing trend in annual maximum flows are observed owing to persistent silting. Considerable disagreement is found between the design magnitudes of flood obtained by the different definitions of hydrologic risk. Such risk is also found to be highly sensitive to the assumed design life period and projections of trend in that period or beyond. Additionally, some critical points on the assumption of a deterministic non-stationary model for an observed natural process are also discussed. The findings highlight the necessity for a unifying framework for assessment and communication of hydrologic risk under transient hydro-climatic conditions. The concepts can also be extended to other applications such as regional hydrologic frequency analysis or development of precipitation intensity-duration-frequency relationships for infrastructure design.

  5. 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....

  6. Dynamically adaptive data-driven simulation of extreme hydrological flows

    KAUST Repository

    Kumar Jain, Pushkar; Mandli, Kyle; Hoteit, Ibrahim; Knio, Omar; Dawson, Clint

    2017-01-01

    evacuation in real-time and through the development of resilient infrastructure based on knowledge of how systems respond to extreme events. Data-driven computational modeling is a critical technology underpinning these efforts. This investigation focuses

  7. On Extreme Events in Banking and Finance

    NARCIS (Netherlands)

    M.R.C. Oordt (Maarten)

    2013-01-01

    textabstractUncertainty and new developments spread at an astonishing speed across the globe in financial markets. The recent extreme events in banking and finance triggered many new questions among academics, policy makers and the general public. Is global diversification at financial

  8. Variability of extreme wet events over Malawi

    Directory of Open Access Journals (Sweden)

    Libanda Brigadier

    2017-01-01

    Full Text Available Adverse effects of extreme wet events are well documented by several studies around the world. These effects are exacerbated in developing countries like Malawi that have insufficient risk reduction strategies and capacity to cope with extreme wet weather. Ardent monitoring of the variability of extreme wet events over Malawi is therefore imperative. The use of the Expert Team on Climate Change Detection and Indices (ETCCDI has been recommended by many studies as an effective way of quantifying extreme wet events. In this study, ETCCDI indices were used to examine the number of heavy, very heavy, and extremely heavy rainfall days; daily and five-day maximum rainfall; very wet and extremely wet days; annual wet days and simple daily intensity. The Standard Normal Homogeneity Test (SNHT was employed at 5% significance level before any statistical test was done. Trend analysis was done using the nonparametric Mann-Kendall statistical test. All stations were found to be homogeneous apart from Mimosa. Trend results show high temporal and spatial variability with the only significant results being: increase in daily maximum rainfall (Rx1day over Karonga and Bvumbwe, increase in five-day maximum rainfall (Rx5day over Bvumbwe. Mzimba and Chileka recorded a significant decrease in very wet days (R95p while a significant increase was observed over Thyolo. Chileka was the only station which observed a significant trend (decrease in extremely wet rainfall (R99p. Mzimba was the only station that reported a significant trend (decrease in annual wet-day rainfall total (PRCPTOT and Thyolo was the only station that reported a significant trend (increase in simple daily intensity (SDII. Furthermore, the findings of this study revealed that, during wet years, Malawi is characterised by an anomalous convergence of strong south-easterly and north-easterly winds. This convergence is the main rain bringing mechanism to Malawi.

  9. Using GRACE Satellite Gravimetry for Assessing Large-Scale Hydrologic Extremes

    Directory of Open Access Journals (Sweden)

    Alexander Y. Sun

    2017-12-01

    Full Text Available Global assessment of the spatiotemporal variability in terrestrial total water storage anomalies (TWSA in response to hydrologic extremes is critical for water resources management. Using TWSA derived from the gravity recovery and climate experiment (GRACE satellites, this study systematically assessed the skill of the TWSA-climatology (TC approach and breakpoint (BP detection method for identifying large-scale hydrologic extremes. The TC approach calculates standardized anomalies by using the mean and standard deviation of the GRACE TWSA corresponding to each month. In the BP detection method, the empirical mode decomposition (EMD is first applied to identify the mean return period of TWSA extremes, and then a statistical procedure is used to identify the actual occurrence times of abrupt changes (i.e., BPs in TWSA. Both detection methods were demonstrated on basin-averaged TWSA time series for the world’s 35 largest river basins. A nonlinear event coincidence analysis measure was applied to cross-examine abrupt changes detected by these methods with those detected by the Standardized Precipitation Index (SPI. Results show that our EMD-assisted BP procedure is a promising tool for identifying hydrologic extremes using GRACE TWSA data. Abrupt changes detected by the BP method coincide well with those of the SPI anomalies and with documented hydrologic extreme events. Event timings obtained by the TC method were ambiguous for a number of river basins studied, probably because the GRACE data length is too short to derive long-term climatology at this time. The BP approach demonstrates a robust wet-dry anomaly detection capability, which will be important for applications with the upcoming GRACE Follow-On mission.

  10. Probabilistic attribution of individual unprecedented extreme events

    Science.gov (United States)

    Diffenbaugh, N. S.

    2016-12-01

    The last decade has seen a rapid increase in efforts to understand the influence of global warming on individual extreme climate events. Although trends in the distributions of climate observations have been thoroughly analyzed, rigorously quantifying the contribution of global-scale warming to individual events that are unprecedented in the observed record presents a particular challenge. This paper describes a method for leveraging observations and climate model ensembles to quantify the influence of historical global warming on the severity and probability of unprecedented events. This approach uses formal inferential techniques to quantify four metrics: (1) the contribution of the observed trend to the event magnitude, (2) the contribution of the observed trend to the event probability, (3) the probability of the observed trend in the current climate and a climate without human influence, and (4) the probability of the event magnitude in the current climate and a climate without human influence. Illustrative examples are presented, spanning a range of climate variables, timescales, and regions. These examples illustrate that global warming can influence the severity and probability of unprecedented extremes. In some cases - particularly high temperatures - this change is indicated by changes in the mean. However, changes in probability do not always arise from changes in the mean, suggesting that global warming can alter the frequency with which complex physical conditions co-occur. Because our framework is transparent and highly generalized, it can be readily applied to a range of climate events, regions, and levels of climate forcing.

  11. Can Concentration - Discharge Relationships Diagnose Material Source During Extreme Events?

    Science.gov (United States)

    Karwan, D. L.; Godsey, S.; Rose, L.

    2017-12-01

    Floods can carry >90% of the basin material exported in a given year as well as alter flow pathways and material sources. In turn, sediment and solute fluxes can increase flood damages and negatively impact water quality and integrate physical and chemical weathering of landscapes and channels. Concentration-discharge (C-Q) relationships are used to both describe export patterns as well as compute them. Metrics for describing C-Q patterns and inferring their controls are vulnerable to infrequent sampling that affects how C-Q relationships are interpolated and interpreted. C-Q relationships are typically evaluated from multiple samples, but because hydrological extremes are rare, data are often unavailable for extreme events. Because solute and sediment C-Q relationships likely respond to changes in hydrologic extremes in different ways, there is a pressing need to define their behavior under extreme conditions, including how to properly sample to capture these patterns. In the absence of such knowledge, improving load estimates in extreme floods will likely remain difficult. Here we explore the use of C-Q relationships to determine when an event alters a watershed system such that it enters a new material source/transport regime. We focus on watersheds with sediment and discharge time series include low-frequency and/or extreme events. For example, we compare solute and sediment patterns in White Clay Creek in southeastern Pennsylvania across a range of flows inclusive of multiple hurricanes for which we have ample ancillary hydrochemical data. TSS is consistently mobilized during high flow events, even during extreme floods associated with hurricanes, and sediment fingerprinting indicates different sediment sources, including in-channel remobilization and landscape erosion, are active at different times. In other words, TSS mobilization in C-Q space is not sensitive to the source of material being mobilized. Unlike sediments, weathering solutes in this watershed

  12. Satellite-Enhanced Dynamical Downscaling of Extreme Events

    Science.gov (United States)

    Nunes, A.

    2015-12-01

    Severe weather events can be the triggers of environmental disasters in regions particularly susceptible to changes in hydrometeorological conditions. In that regard, the reconstruction of past extreme weather events can help in the assessment of vulnerability and risk mitigation actions. Using novel modeling approaches, dynamical downscaling of long-term integrations from global circulation models can be useful for risk analysis, providing more accurate climate information at regional scales. Originally developed at the National Centers for Environmental Prediction (NCEP), the Regional Spectral Model (RSM) is being used in the dynamical downscaling of global reanalysis, within the South American Hydroclimate Reconstruction Project. Here, RSM combines scale-selective bias correction with assimilation of satellite-based precipitation estimates to downscale extreme weather occurrences. Scale-selective bias correction is a method employed in the downscaling, similar to the spectral nudging technique, in which the downscaled solution develops in agreement with its coarse boundaries. Precipitation assimilation acts on modeled deep-convection, drives the land-surface variables, and therefore the hydrological cycle. During the downscaling of extreme events that took place in Brazil in recent years, RSM continuously assimilated NCEP Climate Prediction Center morphing technique precipitation rates. As a result, RSM performed better than its global (reanalysis) forcing, showing more consistent hydrometeorological fields compared with more sophisticated global reanalyses. Ultimately, RSM analyses might provide better-quality initial conditions for high-resolution numerical predictions in metropolitan areas, leading to more reliable short-term forecasting of severe local storms.

  13. Meteorological Drivers of Extreme Air Pollution Events

    Science.gov (United States)

    Horton, D. E.; Schnell, J.; Callahan, C. W.; Suo, Y.

    2017-12-01

    The accumulation of pollutants in the near-surface atmosphere has been shown to have deleterious consequences for public health, agricultural productivity, and economic vitality. Natural and anthropogenic emissions of ozone and particulate matter can accumulate to hazardous concentrations when atmospheric conditions are favorable, and can reach extreme levels when such conditions persist. Favorable atmospheric conditions for pollutant accumulation include optimal temperatures for photochemical reaction rates, circulation patterns conducive to pollutant advection, and a lack of ventilation, dispersion, and scavenging in the local environment. Given our changing climate system and the dual ingredients of poor air quality - pollutants and the atmospheric conditions favorable to their accumulation - it is important to characterize recent changes in favorable meteorological conditions, and quantify their potential contribution to recent extreme air pollution events. To facilitate our characterization, this study employs the recently updated Schnell et al (2015) 1°×1° gridded observed surface ozone and particulate matter datasets for the period of 1998 to 2015, in conjunction with reanalysis and climate model simulation data. We identify extreme air pollution episodes in the observational record and assess the meteorological factors of primary support at local and synoptic scales. We then assess (i) the contribution of observed meteorological trends (if extant) to the magnitude of the event, (ii) the return interval of the meteorological event in the observational record, simulated historical climate, and simulated pre-industrial climate, as well as (iii) the probability of the observed meteorological trend in historical and pre-industrial climates.

  14. A Metastatistical Approach to Satellite Estimates of Extreme Rainfall Events

    Science.gov (United States)

    Zorzetto, E.; Marani, M.

    2017-12-01

    The estimation of the average recurrence interval of intense rainfall events is a central issue for both hydrologic modeling and engineering design. These estimates require the inference of the properties of the right tail of the statistical distribution of precipitation, a task often performed using the Generalized Extreme Value (GEV) distribution, estimated either from a samples of annual maxima (AM) or with a peaks over threshold (POT) approach. However, these approaches require long and homogeneous rainfall records, which often are not available, especially in the case of remote-sensed rainfall datasets. We use here, and tailor it to remotely-sensed rainfall estimates, an alternative approach, based on the metastatistical extreme value distribution (MEVD), which produces estimates of rainfall extreme values based on the probability distribution function (pdf) of all measured `ordinary' rainfall event. This methodology also accounts for the interannual variations observed in the pdf of daily rainfall by integrating over the sample space of its random parameters. We illustrate the application of this framework to the TRMM Multi-satellite Precipitation Analysis rainfall dataset, where MEVD optimally exploits the relatively short datasets of satellite-sensed rainfall, while taking full advantage of its high spatial resolution and quasi-global coverage. Accuracy of TRMM precipitation estimates and scale issues are here investigated for a case study located in the Little Washita watershed, Oklahoma, using a dense network of rain gauges for independent ground validation. The methodology contributes to our understanding of the risk of extreme rainfall events, as it allows i) an optimal use of the TRMM datasets in estimating the tail of the probability distribution of daily rainfall, and ii) a global mapping of daily rainfall extremes and distributional tail properties, bridging the existing gaps in rain gauges networks.

  15. Effect of Using Extreme Years in Hydrologic Model Calibration Performance

    Science.gov (United States)

    Goktas, R. K.; Tezel, U.; Kargi, P. G.; Ayvaz, T.; Tezyapar, I.; Mesta, B.; Kentel, E.

    2017-12-01

    Hydrological models are useful in predicting and developing management strategies for controlling the system behaviour. Specifically they can be used for evaluating streamflow at ungaged catchments, effect of climate change, best management practices on water resources, or identification of pollution sources in a watershed. This study is a part of a TUBITAK project named "Development of a geographical information system based decision-making tool for water quality management of Ergene Watershed using pollutant fingerprints". Within the scope of this project, first water resources in Ergene Watershed is studied. Streamgages found in the basin are identified and daily streamflow measurements are obtained from State Hydraulic Works of Turkey. Streamflow data is analysed using box-whisker plots, hydrographs and flow-duration curves focusing on identification of extreme periods, dry or wet. Then a hydrological model is developed for Ergene Watershed using HEC-HMS in the Watershed Modeling System (WMS) environment. The model is calibrated for various time periods including dry and wet ones and the performance of calibration is evaluated using Nash-Sutcliffe Efficiency (NSE), correlation coefficient, percent bias (PBIAS) and root mean square error. It is observed that calibration period affects the model performance, and the main purpose of the development of the hydrological model should guide calibration period selection. Acknowledgement: This study is funded by The Scientific and Technological Research Council of Turkey (TUBITAK) under Project Number 115Y064.

  16. 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.

  17. Earth's portfolio of extreme sediment transport events

    Science.gov (United States)

    Korup, Oliver

    2012-05-01

    Quantitative estimates of sediment flux and the global cycling of sediments from hillslopes to rivers, estuaries, deltas, continental shelves, and deep-sea basins have a long research tradition. In this context, extremely large and commensurately rare sediment transport events have so far eluded a systematic analysis. To start filling this knowledge gap I review some of the highest reported sediment yields in mountain rivers impacted by volcanic eruptions, earthquake- and storm-triggered landslide episodes, and catastrophic dam breaks. Extreme specific yields, defined here as those exceeding the 95th percentile of compiled data, are ~ 104 t km- 2 yr- 1 if averaged over 1 yr. These extreme yields vary by eight orders of magnitude, but systematically decay with reference intervals from minutes to millennia such that yields vary by three orders of magnitude for a given reference interval. Sediment delivery from natural dam breaks and pyroclastic eruptions dominate these yields for a given reference interval. Even if averaged over 102-103 yr, the contribution of individual disturbances may remain elevated above corresponding catchment denudation rates. I further estimate rates of sediment (re-)mobilisation by individual giant terrestrial and submarine mass movements. Less than 50 postglacial submarine mass movements have involved an equivalent of ~ 10% of the contemporary annual global flux of fluvial sediment to Earth's oceans, while mobilisation rates by individual events rival the decadal-scale sediment discharge from tectonically active orogens such as Taiwan or New Zealand. Sediment flushing associated with catastrophic natural dam breaks is non-stationary and shows a distinct kink at the last glacial-interglacial transition, owing to the drainage of very large late Pleistocene ice-marginal lakes. Besides emphasising the contribution of high-magnitude and low-frequency events to the global sediment cascade, these findings stress the importance of sediment storage

  18. Hydrological impacts of precipitation extremes in the Huaihe River Basin, China.

    Science.gov (United States)

    Yang, Mangen; Chen, Xing; Cheng, Chad Shouquan

    2016-01-01

    Precipitation extremes play a key role in flooding risks over the Huaihe River Basin, which is important to understand their hydrological impacts. Based on observed daily precipitation and streamflow data from 1958 to 2009, eight precipitation indices and three streamflow indices were calculated for the study of hydrological impacts of precipitation extremes. The results indicate that the wet condition intensified in the summer wet season and the drought condition was getting worse in the autumn dry season in the later years of the past 50 years. The river basin had experienced higher heavy rainfall-related flooding risks in summer and more severe drought in autumn in the later of the period. The extreme precipitation events or consecutive heavy rain day events led to the substantial increases in streamflow extremes, which are the main causes of frequent floods in the Huaihe River Basin. The large inter-annual variation of precipitation anomalies in the upper and central Huaihe River Basin are the major contributor for the regional frequent floods and droughts.

  19. Stream Response to an Extreme Defoliation Event

    Science.gov (United States)

    Gold, A.; Loffredo, J.; Addy, K.; Bernhardt, E. S.; Berdanier, A. B.; Schroth, A. W.; Inamdar, S. P.; Bowden, W. B.

    2017-12-01

    Extreme climatic events are known to profoundly impact stream flow and stream fluxes. These events can also exert controls on insect outbreaks, which may create marked changes in stream characteristics. The invasive Gypsy Moth (Lymantria dispar dispar) experiences episodic infestations based on extreme climatic conditions within the northeastern U.S. In most years, gypsy moth populations are kept in check by diseases. In 2016 - after successive years of unusually warm, dry spring and summer weather -gypsy moth caterpillars defoliated over half of Rhode Island's 160,000 forested ha. No defoliation of this magnitude had occurred for more than 30 years. We examined one RI headwater stream's response to the defoliation event in 2016 compared with comparable data in 2014 and 2015. Stream temperature and flow was gauged continuously by USGS and dissolved oxygen (DO) was measured with a YSI EXO2 sonde every 30 minutes during a series of deployments in the spring, summer and fall from 2014-2016. We used the single station, open channel method to estimate stream metabolism metrics. We also assessed local climate and stream temperature data from 2009-2016. We observed changes in stream responses during the defoliation event that suggest changes in ET, solar radiation and heat flux. Although the summer of 2016 had more drought stress (PDSI) than previous years, stream flow occurred throughout the summer, in contrast to several years with lower drought stress when stream flow ceased. Air temperature in 2016 was similar to prior years, but stream temperature was substantially higher than the prior seven years, likely due to the loss of canopy shading. DO declined dramatically in 2016 compared to prior years - more than the rising stream temperatures would indicate. Gross Primary Productivity was significantly higher during the year of the defoliation, indicating more total fixation of inorganic carbon from photo-autotrophs. In 2016, Ecosystem Respiration was also higher and Net

  20. A pentatonic classification of extreme events

    International Nuclear Information System (INIS)

    Eliazar, Iddo; Cohen, Morrel H.

    2015-01-01

    In this paper we present a classification of the extreme events – very small and very large outcomes – of positive-valued random variables. The classification distinguishes five different categories of randomness, ranging from the very ‘mild’ to the very ‘wild’. In analogy with the common five-tone musical scale we term the classification ‘pentatonic’. The classification is based on the analysis of the inherent Gibbsian ‘forces’ and ‘temperatures’ existing on the logarithmic scale of the random variables under consideration, and provides a statistical-physics insight regarding the nature of these random variables. The practical application of the pentatonic classification is remarkably straightforward, it can be performed by non-experts, and it is demonstrated via an array of examples

  1. Extreme scattering events towards two young pulsars

    Science.gov (United States)

    Kerr, M.; Coles, W. A.; Ward, C. A.; Johnston, S.; Tuntsov, A. V.; Shannon, R. M.

    2018-03-01

    We have measured the scintillation properties of 151 young, energetic pulsars with the Parkes radio telescope and have identified two extreme scattering events (ESEs). Towards PSR J1057-5226, we discovered a 3 yr span of strengthened scattering during which the variability in flux density and the scintillation bandwidth decreased markedly. The transverse size of the scattering region is ˜23 au, and strong flux density enhancement before and after the ESE may arise from refractive focusing. Long observations reveal scintillation arcs characteristic of interference between rays scattered at large angles, and the clearest arcs appear during the ESE. The arcs suggest scattering by a screen 100-200 pc from the Earth, perhaps ionized filamentary structure associated with the boundary of the local bubble(s). Towards PSR J1740-3015, we observed a `double dip' in the measured flux density similar to ESEs observed towards compact extragalactic radio sources. The observed shape is consistent with that produced by a many-au scale diverging plasma lens with electron density ˜500 cm-3. The continuing ESE is at least 1500 d long, making it the longest detected event to date. These detections, with materially different observational signatures, indicate that well-calibrated pulsar monitoring is a keen tool for ESE detection and interstellar medium (ISM) diagnostics. They illustrate the strong role au-scale non-Kolmogorov density fluctuations and the local ISM structure play in such events and are key to understanding both their intrinsic physics and their impact on other phenomena, particularly fast radio bursts.

  2. Coupling hydrologic and hydraulic models to take into consideration retention effects on extreme peak discharges in Switzerland

    Science.gov (United States)

    Felder, Guido; Zischg, Andreas; Weingartner, Rolf

    2015-04-01

    Estimating peak discharges with very low probabilities is still accompanied by large uncertainties. Common estimation methods are usually based on extreme value statistics applied to observed time series or to hydrological model outputs. However, such methods assume the system to be stationary and do not specifically consider non-stationary effects. Observed time series may exclude events where peak discharge is damped by retention effects, as this process does not occur until specific thresholds, possibly beyond those of the highest measured event, are exceeded. Hydrological models can be complemented and parameterized with non-linear functions. However, in such cases calibration depends on observed data and non-stationary behaviour is not deterministically calculated. Our study discusses the option of considering retention effects on extreme peak discharges by coupling hydrological and hydraulic models. This possibility is tested by forcing the semi-distributed deterministic hydrological model PREVAH with randomly generated, physically plausible extreme precipitation patterns. The resulting hydrographs are then used to force the hydraulic model BASEMENT-ETH (riverbed in 1D, potential inundation areas in 2D). The procedure ensures that the estimated extreme peak discharge does not exceed the physical limit given by the riverbed capacity and that the dampening effect of inundation processes on peak discharge is considered.

  3. PULSAR OBSERVATIONS OF EXTREME SCATTERING EVENTS

    International Nuclear Information System (INIS)

    Coles, W. A.; Kerr, M.; Shannon, R. M.; Hobbs, G. B.; Manchester, R. N.; Dai, S.; Ravi, V.; Reardon, D.; Toomey, L.; Zhu, X. J.; You, X.-P.; Bailes, M.; Straten, W. van; Bhat, N. D. R.; Burke-Spolaor, S.; Keith, M. J.; Levin, Y.; Osłowski, S.; Wang, J. B.; Wen, L.

    2015-01-01

    Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage of a “diverging plasma lens” across the line of sight (LOS). Modeling the refraction of such a lens indicates that the structure size must be of the order of AU and the electron density of the order of 10s of cm −3 . Similar structures have been observed in measurements of pulsar intensity scintillation and group delay. Here we report observations of two ESEs, showing increases in both intensity scintillation and dispersion made with the Parkes Pulsar Timing Array. These allow us to make more complete models of the ESE, including an estimate of the “outer-scale” of the turbulence in the plasma lens. These observations clearly show that the ESE structure is fully turbulent on an AU scale. They provide some support for the idea that the structures are extended along the LOS, such as would be the case for a scattering shell. The dispersion measurements also show a variety of AU scale structures that would not be called ESEs, yet involve electron density variations typical of ESEs and likely have the same origin

  4. Pulsar Observations of Extreme Scattering Events

    Science.gov (United States)

    Coles, W. A.; Kerr, M.; Shannon, R. M.; Hobbs, G. B.; Manchester, R. N.; You, X.-P.; Bailes, M.; Bhat, N. D. R.; Burke-Spolaor, S.; Dai, S.; Keith, M. J.; Levin, Y.; Osłowski, S.; Ravi, V.; Reardon, D.; Toomey, L.; van Straten, W.; Wang, J. B.; Wen, L.; Zhu, X. J.

    2015-08-01

    Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage of a “diverging plasma lens” across the line of sight (LOS). Modeling the refraction of such a lens indicates that the structure size must be of the order of AU and the electron density of the order of 10s of cm-3. Similar structures have been observed in measurements of pulsar intensity scintillation and group delay. Here we report observations of two ESEs, showing increases in both intensity scintillation and dispersion made with the Parkes Pulsar Timing Array. These allow us to make more complete models of the ESE, including an estimate of the “outer-scale” of the turbulence in the plasma lens. These observations clearly show that the ESE structure is fully turbulent on an AU scale. They provide some support for the idea that the structures are extended along the LOS, such as would be the case for a scattering shell. The dispersion measurements also show a variety of AU scale structures that would not be called ESEs, yet involve electron density variations typical of ESEs and likely have the same origin.

  5. PULSAR OBSERVATIONS OF EXTREME SCATTERING EVENTS

    Energy Technology Data Exchange (ETDEWEB)

    Coles, W. A. [ECE Department, University of California at San Diego, La Jolla, CA, 92093-0407 (United States); Kerr, M.; Shannon, R. M.; Hobbs, G. B.; Manchester, R. N.; Dai, S.; Ravi, V.; Reardon, D.; Toomey, L.; Zhu, X. J. [ATNF, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia); You, X.-P. [Southwest University, Chongqing (China); Bailes, M.; Straten, W. van [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Bhat, N. D. R. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia); Burke-Spolaor, S. [California Institute of Technology, Pasadena, 1200 E California Boulevard, CA 91125 (United States); Keith, M. J. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Levin, Y. [Monash Center for Astrophysics, School of Physics and Astronomy, Monash University, Vic 3800 (Australia); Osłowski, S. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Wang, J. B. [Xinjiang Astronomical Observatory, Chinese Academy of Science, 150 Science 1-Street, Urumqi, Xinjiang, 830011 (China); Wen, L., E-mail: bcoles@ucsd.edu [University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

    2015-08-01

    Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage of a “diverging plasma lens” across the line of sight (LOS). Modeling the refraction of such a lens indicates that the structure size must be of the order of AU and the electron density of the order of 10s of cm{sup −3}. Similar structures have been observed in measurements of pulsar intensity scintillation and group delay. Here we report observations of two ESEs, showing increases in both intensity scintillation and dispersion made with the Parkes Pulsar Timing Array. These allow us to make more complete models of the ESE, including an estimate of the “outer-scale” of the turbulence in the plasma lens. These observations clearly show that the ESE structure is fully turbulent on an AU scale. They provide some support for the idea that the structures are extended along the LOS, such as would be the case for a scattering shell. The dispersion measurements also show a variety of AU scale structures that would not be called ESEs, yet involve electron density variations typical of ESEs and likely have the same origin.

  6. Uncertainties in hydrological extremes projections and its effects on decision-making processes in an Amazonian sub-basin.

    Science.gov (United States)

    Andres Rodriguez, Daniel; Garofolo, Lucas; Lazaro Siqueira Junior, Jose

    2013-04-01

    Uncertainties in Climate Change projections are affected by irreducible uncertainties due to knowledge's limitations, chaotic nature of climate system and human decision-making process. Such uncertainties affect the impact studies, complicating the decision-making process aimed at mitigation and adaptation. However, these uncertainties allow the possibility to develop exploratory analyses on system's vulnerability to different sceneries. Through these kinds of analyses it is possible to identify critical issues, which must be deeper studied. For this study we used several future's projections from General Circulation Models to feed a Hydrological Model, applied to the Amazonian sub-basin of Ji-Paraná. Hydrological Model integrations are performed for present historical time (1970-1990) and for future period (2010-2100). Extreme values analyses are performed to each simulated time series and results are compared with extremes events in present time. A simple approach to identify potential vulnerabilities consists of evaluating the hydrologic system response to climate variability and extreme events observed in the past, comparing them with the conditions projected for the future. Thus it is possible to identify critical issues that need attention and more detailed studies. For the goal of this work, we used socio-economic data from Brazilian Institute of Geography and Statistics, the Operator of the National Electric System, the Brazilian National Water Agency and scientific and press published information. This information is used to characterize impacts associated to extremes hydrological events in the basin during the present historical time and to evaluate potential impacts in the future face to the different hydrological projections. Results show inter-model variability results in a broad dispersion on projected extreme's values. The impact of such dispersion is differentiated for different aspects of socio-economic and natural systems and must be carefully

  7. Ensemble reconstruction of spatio-temporal extreme low-flow events in France since 1871

    Science.gov (United States)

    Caillouet, Laurie; Vidal, Jean-Philippe; Sauquet, Eric; Devers, Alexandre; Graff, Benjamin

    2017-06-01

    The length of streamflow observations is generally limited to the last 50 years even in data-rich countries like France. It therefore offers too small a sample of extreme low-flow events to properly explore the long-term evolution of their characteristics and associated impacts. To overcome this limit, this work first presents a daily 140-year ensemble reconstructed streamflow dataset for a reference network of near-natural catchments in France. This dataset, called SCOPE Hydro (Spatially COherent Probabilistic Extended Hydrological dataset), is based on (1) a probabilistic precipitation, temperature, and reference evapotranspiration downscaling of the Twentieth Century Reanalysis over France, called SCOPE Climate, and (2) continuous hydrological modelling using SCOPE Climate as forcings over the whole period. This work then introduces tools for defining spatio-temporal extreme low-flow events. Extreme low-flow events are first locally defined through the sequent peak algorithm using a novel combination of a fixed threshold and a daily variable threshold. A dedicated spatial matching procedure is then established to identify spatio-temporal events across France. This procedure is furthermore adapted to the SCOPE Hydro 25-member ensemble to characterize in a probabilistic way unrecorded historical events at the national scale. Extreme low-flow events are described and compared in a spatially and temporally homogeneous way over 140 years on a large set of catchments. Results highlight well-known recent events like 1976 or 1989-1990, but also older and relatively forgotten ones like the 1878 and 1893 events. These results contribute to improving our knowledge of historical events and provide a selection of benchmark events for climate change adaptation purposes. Moreover, this study allows for further detailed analyses of the effect of climate variability and anthropogenic climate change on low-flow hydrology at the scale of France.

  8. Adaptation to hydrological extremes through insurance: a financial fund simulation model under changing scenarios

    Science.gov (United States)

    Guzman, Diego; Mohor, Guilherme; Câmara, Clarissa; Mendiondo, Eduardo

    2017-04-01

    Researches from around the world relate global environmental changes with the increase of vulnerability to extreme events, such as heavy and scarce precipitations - floods and droughts. Hydrological disasters have caused increasing losses in recent years. Thus, risk transfer mechanisms, such as insurance, are being implemented to mitigate impacts, finance the recovery of the affected population, and promote the reduction of hydrological risks. However, among the main problems in implementing these strategies, there are: First, the partial knowledge of natural and anthropogenic climate change in terms of intensity and frequency; Second, the efficient risk reduction policies require accurate risk assessment, with careful consideration of costs; Third, the uncertainty associated with numerical models and input data used. The objective of this document is to introduce and discuss the feasibility of the application of Hydrological Risk Transfer Models (HRTMs) as a strategy of adaptation to global climate change. The article shows the development of a methodology for the collective and multi-sectoral vulnerability management, facing the hydrological risk in the long term, under an insurance funds simulator. The methodology estimates the optimized premium as a function of willingness to pay (WTP) and the potential direct loss derived from hydrological risk. The proposed methodology structures the watershed insurance scheme in three analysis modules. First, the hazard module, which characterizes the hydrologic threat from the recorded series input or modelled series under IPCC / RCM's generated scenarios. Second, the vulnerability module calculates the potential economic loss for each sector1 evaluated as a function of the return period "TR". Finally, the finance module determines the value of the optimal aggregate premium by evaluating equiprobable scenarios of water vulnerability; taking into account variables such as the maximum limit of coverage, deductible

  9. 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

  10. A Fourier analysis of extremal events

    DEFF Research Database (Denmark)

    Zhao, Yuwei

    is the 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...

  11. Responses of diatom communities to hydrological processes during rainfall events

    Science.gov (United States)

    Wu, Naicheng; Faber, Claas; Ulrich, Uta; Fohrer, Nicola

    2015-04-01

    The importance of diatoms as a tracer of hydrological processes has been recently recognized (Pfister et al. 2009, Pfister et al. 2011, Tauro et al. 2013). However, diatom variations in a short-term scale (e.g., sub-daily) during rainfall events have not been well documented yet. In this study, rainfall event-based diatom samples were taken at the outlet of the Kielstau catchment (50 km2), a lowland catchment in northern Germany. A total of nine rainfall events were caught from May 2013 to April 2014. Non-metric multidimensional scaling (NMDS) revealed that diatom communities of different events were well separated along NMDS axis I and II, indicating a remarkable temporal variation. By correlating water level (a proxy of discharge) and different diatom indices, close relationships were found. For example, species richness, biovolume (μm3), Shannon diversity and moisture index01 (%, classified according to van Dam et al. 1994) were positively related with water level at the beginning phase of the rainfall (i.e. increasing limb of discharge peak). However, in contrast, during the recession limb of the discharge peak, diatom indices showed distinct responses to water level declines in different rainfall events. These preliminary results indicate that diatom indices are highly related to hydrological processes. The next steps will include finding out the possible mechanisms of the above phenomena, and exploring the contributions of abiotic variables (e.g., hydrologic indices, nutrients) to diatom community patterns. Based on this and ongoing studies (Wu et al. unpublished data), we will incorporate diatom data into End Member Mixing Analysis (EMMA) and select the tracer set that is best suited for separation of different runoff components in our study catchment. Keywords: Diatoms, Rainfall event, Non-metric multidimensional scaling, Hydrological process, Indices References: Pfister L, McDonnell JJ, Wrede S, Hlúbiková D, Matgen P, Fenicia F, Ector L, Hoffmann L

  12. Spatially explicit modelling of extreme weather and climate events ...

    African Journals Online (AJOL)

    The reality of climate change continues to influence the intensity and frequency of extreme weather events such as heat waves, droughts, floods, and landslides. The impacts of the cumulative interplay of these extreme weather and climate events variation continue to perturb governments causing a scramble into formation ...

  13. Alternative measures of risk of extreme events in decision trees

    International Nuclear Information System (INIS)

    Frohwein, H.I.; Lambert, J.H.; Haimes, Y.Y.

    1999-01-01

    A need for a methodology to control the extreme events, defined as low-probability, high-consequence incidents, in sequential decisions is identified. A variety of alternative and complementary measures of the risk of extreme events are examined for their usability as objective functions in sequential decisions, represented as single- or multiple-objective decision trees. Earlier work had addressed difficulties, related to non-separability, with the minimization of some measures of the risk of extreme events in sequential decisions. In an extension of these results, it is shown how some non-separable measures of the risk of extreme events can be interpreted in terms of separable constituents of risk, thereby enabling a wider class of measures of the risk of extreme events to be handled in a straightforward manner in a decision tree. Also for extreme events, results are given to enable minimax- and Hurwicz-criterion analyses in decision trees. An example demonstrates the incorporation of different measures of the risk of extreme events in a multi-objective decision tree. Conceptual formulations for optimizing non-separable measures of the risk of extreme events are identified as an important area for future investigation

  14. Economics of extreme weather events: Terminology and regional impact models

    OpenAIRE

    Jahn, Malte

    2015-01-01

    Impacts of extreme weather events are relevant for regional (in the sense of subnational) economies and in particular cities in many aspects. Cities are the cores of economic activity and the amount of people and assets endangered by extreme weather events is large, even under the current climate. A changing climate with changing extreme weather patterns and the process of urbanization will make the whole issue even more relevant in the future. In this paper, definitions and terminology in th...

  15. The need of the change of the conceptualisation of hydrologic processes under extreme conditions – taking reference evapotranspiration as an example

    Directory of Open Access Journals (Sweden)

    S. Liu

    2015-06-01

    Full Text Available What a hydrological model displays is the relationships between the output and input in daily, monthly, yearly and other temporal scales. In the case of climate change or other environment changes, the input of the hydrological model may show a gradual or abrupt change. There have been numerous documented studies to explore the response of output of the hydrological models to the change of the input with scenario simulation. Most of the studies assumed that the conceptualisation of hydrologic processes will remain, which may be true for the gradual change of the input. However, under extreme conditions the conceptualisation of hydrologic processes may be completely changed. Taking an example of the Allen's formula to calculate crop reference evapotranspiration (ET0 as a simple hydrological model, we analyze the alternation of the extreme in ET0 from 1955 to 2012 at the Chongling Experimental Station located in Hebei Province, China. The relationships between ET0 and the meteorological factors for the average values, minimum (maximum values at daily, monthly and annual scales are revealed. It is found the extreme of the output can follow the extreme of the input better when their relationship is more linear. For non-liner relationship, the extreme of the input cannot at all be reflected from the extreme of the output. Relatively, extreme event at daily scale is harder to be shown than that at monthly scale. The result implicates that a routine model may not be able to catch the response to extreme events and it is even more so as we extrapolate models to higher temperature/CO2 conditions in the future. Some possible choices for the improvements are suggested for predicting hydrological extremes.

  16. Coping with extreme climate events: Institutional flocking

    NARCIS (Netherlands)

    Koppen, van C.S.A.; Mol, A.P.J.; Tatenhove, van J.P.M.

    2010-01-01

    The article explores the governance structures that would be needed to cope with extreme and unpredictable climate change. The impacts on the Netherlands of a Gulf Stream collapse in the Northern Atlantic are taken as a case. This hypothetical situation of serious risks and high uncertainties

  17. A perturbed hydrological cycle during Oceanic Anoxic Event 2

    NARCIS (Netherlands)

    van Helmond, N.A.G.M.; Sluijs, A.; Reichart, G.J; Sinninghe Damsté, J.S.; Slomp, C.P.; Brinkhuis, H.

    2014-01-01

    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2; ca. 94 Ma) was one of the largest global carbon cycle perturbations during the Phanerozoic. OAE2 represents an important, although extreme, case study for modern trends because widespread anoxia and enhanced organic carbon burial during OAE2 were

  18. Extreme meteorological events and nuclear facilities safety

    International Nuclear Information System (INIS)

    Almeida, Patricia Moco Princisval

    2006-01-01

    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)

  19. Large-scale Meteorological Patterns Associated with Extreme Precipitation Events over Portland, OR

    Science.gov (United States)

    Aragon, C.; Loikith, P. C.; Lintner, B. R.; Pike, M.

    2017-12-01

    Extreme precipitation events can have profound impacts on human life and infrastructure, with broad implications across a range of stakeholders. Changes to extreme precipitation events are a projected outcome of climate change that warrants further study, especially at regional- to local-scales. While global climate models are generally capable of simulating mean climate at global-to-regional scales with reasonable skill, resiliency and adaptation decisions are made at local-scales where most state-of-the-art climate models are limited by coarse resolution. Characterization of large-scale meteorological patterns associated with extreme precipitation events at local-scales can provide climatic information without this scale limitation, thus facilitating stakeholder decision-making. This research will use synoptic climatology as a tool by which to characterize the key large-scale meteorological patterns associated with extreme precipitation events in the Portland, Oregon metro region. Composite analysis of meteorological patterns associated with extreme precipitation days, and associated watershed-specific flooding, is employed to enhance understanding of the climatic drivers behind such events. The self-organizing maps approach is then used to characterize the within-composite variability of the large-scale meteorological patterns associated with extreme precipitation events, allowing us to better understand the different types of meteorological conditions that lead to high-impact precipitation events and associated hydrologic impacts. A more comprehensive understanding of the meteorological drivers of extremes will aid in evaluation of the ability of climate models to capture key patterns associated with extreme precipitation over Portland and to better interpret projections of future climate at impact-relevant scales.

  20. Effects of Extreme Events on Arsenic Cycling in Salt Marshes

    Science.gov (United States)

    Northrup, Kristy; Capooci, Margaret; Seyfferth, Angelia L.

    2018-03-01

    Extreme events such as storm surges, intense precipitation, and supermoons cause anomalous and large fluctuations in water level in tidal salt marshes, which impacts the sediment biogeochemistry that dictates arsenic (As) cycling. In addition to changes in water level, which impacts soil redox potential, these extreme events may also change salinity due to freshwater inputs from precipitation or saltwater inputs due to surge. It is currently unknown how As mobility in tidal salt marshes will be impacted by extreme events, as fluctuations in salinity and redox potential may act synergistically to mobilize As. To investigate impacts of extreme events on As cycling in tidal salt marshes, we conducted a combined laboratory and field investigation. We monitored pore water and soil samples before, during, and after two extreme events: a supermoon lunar eclipse followed by a storm surge and precipitation induced by Hurricane Joaquin in fall 2015 at the St. Jones Reserve in Dover, Delaware, a representative tidal salt marsh in the Mid-Atlantic United States. We also conducted soil incubations of marsh sediments in batch and in flow-through experiments in which redox potential and/or salinity were manipulated. Field investigations showed that pore water As was inversely proportional to redox potential. During the extreme events, a distinct pulse of As was observed in the pore water with maximum salinity. Combined field and laboratory investigations revealed that this As pulse is likely due to rapid changes in salinity. These results have implications for As mobility in the face of extreme weather variability.

  1. 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.

  2. Hydrodynamic modelling of extreme flood events in the Kashmir valley in India

    Science.gov (United States)

    Jain, Manoj; Parvaze, Sabah

    2017-04-01

    Floods are one of the most predominant, costly and deadly hazards of all natural vulnerabilities. Every year, floods exert a heavy toll on human life and property in many parts of the world. The prediction of river stages and discharge during flood extremes plays a vital role in planning structural and non-structural measures of flood management. The predictions are also valuable to prepare the flood inundation maps and river floodplain zoning. In the Kashmir Valley, floods occur mainly and very often in the Jhelum Basin mostly due to extreme precipitation events and rugged mountainous topography of the basin. These floods cause extreme damage to life and property in the valley from time to time. Excessive rainfall, particularly in higher sub-catchments causes the snow to melt resulting in excessive runoff downhill to the streams causing floods in the Kashmir Valley where Srinagar city is located. However, very few hydrological studies have been undertaken for the Jhelum Basin mainly due to non-availability of hydrological data due to very complex mountainous terrain. Therefore, the present study has been conducted to model the extreme flood events in the Jhelum Basin in Kashmir Valley. An integrated NAM and MIKE 11 HD model has been setup for Jhelum basin up to Ram Munshi Bagh gauging site and then four most extreme historical flood events in the time series has been analyzed separately including the most recent and most extreme flood event of 2014. In September 2014, the Kashmir Valley witnessed the most severe flood in the past 60 years due to catastrophic rainfall from 1st to 6th September wherein the valley received unprecedented rainfall of more than 650 mm in just 3 days breaking record of many decades. The MIKE 11 HD and NAM model has been calibrated using 21 years (1985-2005) data and validated using 9 years (2006-2014) data. The efficiency indices of the model for calibration and validation period is 0.749 and 0.792 respectively. The model simulated

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

    International Nuclear Information System (INIS)

    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.

    2010-01-01

    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 place. A

  4. Public perceptions of climate change and extreme weather events

    Science.gov (United States)

    Bruine de Bruin, W.; Dessai, S.; Morgan, G.; Taylor, A.; Wong-Parodi, G.

    2013-12-01

    Climate experts face a serious communication challenge. Public debate about climate change continues, even though at the same time people seem to complain about extreme weather events becoming increasingly common. As compared to the abstract concept of ';climate change,' (changes in) extreme weather events are indeed easier to perceive, more vivid, and personally relevant. Public perception research in different countries has suggested that people commonly expect that climate change will lead to increases in temperature, and that unseasonably warm weather is likely to be interpreted as evidence of climate change. However, relatively little is known about whether public concerns about climate change may also be driven by changes in other types of extreme weather events, such as exceptional amounts of precipitation or flooding. We therefore examined how perceptions of and personal experiences with changes in these specific weather events are related to public concerns about climate change. In this presentation, we will discuss findings from two large public perception surveys conducted in flood-prone Pittsburgh, Pennsylvania (US) and with a national sample in the UK, where extreme flooding has recently occurred across the country. Participants completed questions about their perceptions of and experiences with specific extreme weather events, and their beliefs about climate change. We then conducted linear regressions to predict individual differences in climate-change beliefs, using perceptions of and experiences with specific extreme weather events as predictors, while controlling for demographic characteristics. The US study found that people (a) perceive flood chances to be increasing over the decades, (b) believe climate change to play a role in increases in future flood chances, and (c) would interpret future increases in flooding as evidence for climate change. The UK study found that (a) UK residents are more likely to perceive increases in ';wet' events such

  5. National water summary 1988-89: Hydrologic events and floods and droughts

    Science.gov (United States)

    Paulson, Richard W.; Chase, Edith B.; Roberts, Robert S.; Moody, David W.

    1991-01-01

    National Water Summary 1988-89 - Hydrologic Events and Floods and Droughts documents the occurrence in the United States, Puerto Rico, and the U.S. Virgin Islands of two types of extreme hydrologic events floods and droughts on the basis of analysis of stream-discharge data. This report details, for the first time, the areal extent of the most notable floods and droughts in each State, portrays their severity in terms of annual peak discharge for floods and annual departure from long-term discharge for droughts for selected stream-gaging stations, and estimates how frequently floods and droughts of such severity can be expected to recur. These two types of extreme hydrologic events are very different in their duration, cause, areal extent, and effect on human activities. Floods are short-term phenomena that typically last only a few hours to a few days and are associated with weather systems that produce unusually large amounts of rain or that cause snow to melt quickly. The large amount of runoff produced causes rivers to overflow their banks and, thus, is highly dangerous to human life and property. In contrast, droughts are long-term phenomena that typically persist for months to a decade or more and are associated with the absence of precipitation producing weather. They affect large geographic areas that can be statewide, regional, or even nationwide in extent. Droughts can cause great economic hardship and even loss of life in developing countries, although the loss of life results almost wholly from diminished water supplies and catastrophic crop failures rather than from the direct and obvious peril to human life that is common to floods. The following discussion is an overview of the three parts of this 1988-89 National Water Summary "Hydrologic Conditions and Water-Related Events, Water Years 1988-89," "Hydrologic Perspectives on Water Issues," and "State Summaries of Floods and Droughts." Background information on sources of atmospheric moisture to the

  6. Opportunities and constraints for improved water resources management under increasing hydrological extremes

    Science.gov (United States)

    Wada, Y.

    2017-12-01

    Increased occurrence of extreme climate events is one of the most damaging consequences of global climate change today and in the future. Estimating the impacts of such extreme events on global and regional water resources is therefore crucial for quantifying increasing risks from climate change. The quest for water security has been a struggle throughout human history. Only in recent years has the scale of this quest moved beyond the local, to the national and regional scales and to the planet itself. Absent or unreliable water supply, sanitation and irrigation services, unmitigated floods and droughts, and degraded water environments severely impact half of the planet's population. The scale and complexity of the water challenges faced by society, particularly but not only in the world's poorest regions, are now recognized, as is the imperative of overcoming these challenges for a stable and equitable world. IIASA's Water Futures and Solutions Initiative (WFAS) is an unprecedented inter-disciplinary scientific initiative to identify robust and adaptive portfolios of optional solutions across different economic sectors, including agriculture, energy and industry, and to test these solution-portfolios with multi-model ensembles of hydrologic and sector models to obtain a clearer picture of the trade-offs, risks, and opportunities. The results of WFaS scenarios and models provide a basis for long-term strategic planning of water resource development under changing environments and increasing climate extremes. And given the complexity of the water system, WFaS uniquely provides policy makers with optional sets of solutions that work together and that can be easily adapted as circumstances change in the future. As WFaS progresses, it will establish a network involving information exchange, mutual learning and horizontal cooperation across teams of researchers, public and private decision makers and practitioners exploring solutions at regional, national and local

  7. 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.

  8. Extreme event statistics in a drifting Markov chain

    Science.gov (United States)

    Kindermann, Farina; Hohmann, Michael; Lausch, Tobias; Mayer, Daniel; Schmidt, Felix; Widera, Artur

    2017-07-01

    We analyze extreme event statistics of experimentally realized Markov chains with various drifts. Our Markov chains are individual trajectories of a single atom diffusing in a one-dimensional periodic potential. Based on more than 500 individual atomic traces we verify the applicability of the Sparre Andersen theorem to our system despite the presence of a drift. We present detailed analysis of four different rare-event statistics for our system: the distributions of extreme values, of record values, of extreme value occurrence in the chain, and of the number of records in the chain. We observe that, for our data, the shape of the extreme event distributions is dominated by the underlying exponential distance distribution extracted from the atomic traces. Furthermore, we find that even small drifts influence the statistics of extreme events and record values, which is supported by numerical simulations, and we identify cases in which the drift can be determined without information about the underlying random variable distributions. Our results facilitate the use of extreme event statistics as a signal for small drifts in correlated trajectories.

  9. Future Extreme Event Vulnerability in the Rural Northeastern United States

    Science.gov (United States)

    Winter, J.; Bowen, F. L.; Partridge, T.; Chipman, J. W.

    2017-12-01

    Future climate change impacts on humans will be determined by the convergence of evolving physical climate and socioeconomic systems. Of particular concern is the intersection of extreme events and vulnerable populations. Rural areas of the Northeastern United States have experienced increased temperature and precipitation extremes, especially over the past three decades, and face unique challenges due to their physical isolation, natural resources dependent economies, and high poverty rates. To explore the impacts of future extreme events on vulnerable, rural populations in the Northeast, we project extreme events and vulnerability indicators to identify where changes in extreme events and vulnerable populations coincide. Specifically, we analyze future (2046-2075) maximum annual daily temperature, minimum annual daily temperature, maximum annual daily precipitation, and maximum consecutive dry day length for Representative Concentration Pathways (RCP) 4.5 and 8.5 using four global climate models (GCM) and a gridded observational dataset. We then overlay those projections with estimates of county-level population and relative income for 2060 to calculate changes in person-events from historical (1976-2005), with a focus on Northeast counties that have less than 250,000 people and are in the bottom income quartile. We find that across the rural Northeast for RCP4.5, heat person-events per year increase tenfold, far exceeding decreases in cold person-events and relatively small changes in precipitation and drought person-events. Counties in the bottom income quartile have historically (1976-2005) experienced a disproportionate number of heat events, and counties in the bottom two income quartiles are projected to experience a greater heat event increase by 2046-2075 than counties in the top two income quartiles. We further explore the relative contributions of event frequency, population, and income changes to the total and geographic distribution of climate change

  10. Attribution of extreme weather and climate-related events.

    Science.gov (United States)

    Stott, Peter A; Christidis, Nikolaos; Otto, Friederike E L; Sun, Ying; Vanderlinden, Jean-Paul; van Oldenborgh, Geert Jan; Vautard, Robert; von Storch, Hans; Walton, Peter; Yiou, Pascal; Zwiers, Francis W

    2016-01-01

    Extreme weather and climate-related events occur in a particular place, by definition, infrequently. It is therefore challenging to detect systematic changes in their occurrence given the relative shortness of observational records. However, there is a clear interest from outside the climate science community in the extent to which recent damaging extreme events can be linked to human-induced climate change or natural climate variability. Event attribution studies seek to determine to what extent anthropogenic climate change has altered the probability or magnitude of particular events. They have shown clear evidence for human influence having increased the probability of many extremely warm seasonal temperatures and reduced the probability of extremely cold seasonal temperatures in many parts of the world. The evidence for human influence on the probability of extreme precipitation events, droughts, and storms is more mixed. Although the science of event attribution has developed rapidly in recent years, geographical coverage of events remains patchy and based on the interests and capabilities of individual research groups. The development of operational event attribution would allow a more timely and methodical production of attribution assessments than currently obtained on an ad hoc basis. For event attribution assessments to be most useful, remaining scientific uncertainties need to be robustly assessed and the results clearly communicated. This requires the continuing development of methodologies to assess the reliability of event attribution results and further work to understand the potential utility of event attribution for stakeholder groups and decision makers. WIREs Clim Change 2016, 7:23-41. doi: 10.1002/wcc.380 For further resources related to this article, please visit the WIREs website.

  11. 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.

  12. Vulnerability and Sensitivity of Women and the Aged to Hydrological Extremes in Rural Communities of South Eastern Nigeria

    Science.gov (United States)

    Mbajiorgu, Constantine; Ezenne, Gloria I.; Ndulue, Emeka L.

    2017-04-01

    Annual rainfall total of Southeastern Nigeria varies widely from year to year and across the seasons. Southeastern Nigeria is marked with two distinctive seasons, namely: the rainy season (occurs March through November) and the dry season (December through February). Highest daily rainfall of this area occurs in the months of July through September. Climate change has brought about either prolonged rainy or dry season in this region. Flash floods are common features in Southeastern Nigeria during the rainy (wet) season, but the unprecedented floods of 2012 represent the worst with 21 million people displaced, 597,476 houses destroyed or damaged, over 363 people killed and an estimated loss of USD 19.6 billion. Hydrological extremes such as these affect men and women differently because of the different roles socio-culturally assigned to them. Women are more vulnerable and sensitive to floods and drought because of their conventional gender responsibilities. This study assesses how women and the elderly of rural communities of Southeastern Nigeria are affected by hydrological extremes, their vulnerability to the effects as well as risk reduction approaches to cope with and/or adapt to the impacts of climate change. In the study area, women are predominantly the providers of food, water and fuel, and climate change has adverse impacts on all three. Women in these rural communities practice subsistence farming during the rainy season. Their farm lands are submerged during flood events destroying their crops and they are helpless during prolonged dry seasons. Inadequacy of hydrological data makes it difficult to predict and forecast hydrological extremes in the region. Several other factors exacerbate vulnerability of women and the aged to the impacts of hydrological extremes, such as rural poverty, limited livelihood options, education, lack of basic services, and socio-cultural norms. The poverty level affects their resilience and recovery from any flood disaster. It

  13. Methodology for featuring and assessing extreme climatic events

    International Nuclear Information System (INIS)

    Malleron, N.; Bernardara, P.; Benoit, M.; Parey, S.; Perret, C.

    2013-01-01

    The setting up of a nuclear power plant on a particular site requires the assessment of risks linked to extreme natural events like flooding or earthquakes. As a consequence of the Fukushima accident EDF proposes to take into account even rarer events in order to improve the robustness of the facility all over its operating life. This article presents the methodology used by EDF to analyse a set of data in a statistical way in order to extract extreme values. This analysis is based on the theory of extreme values and is applied to the extreme values of the flow rate in the case of a river overflowing. This methodology is made of 6 steps: 1) selection of the event, of its featuring parameter and of its probability, for instance the question is what is the flow rate of a flooding that has a probability of 10 -3 to happen, 2) to collect data over a long period of time (or to recover data from past periods), 3) to extract extreme values from the data, 4) to find an adequate statistical law that fits the spreading of the extreme values, 5) the selected statistical law must be validated through visual or statistical tests, and 6) the computation of the flow rate of the event itself. (A.C.)

  14. 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.

  15. Meteorological and hydrological extremes derived from taxation records: case study for south-western Moravia (Czech Republic)

    Science.gov (United States)

    Chromá, Kateřina; Brázdil, Rudolf; Valášek, Hubert; Zahradníček, Pavel

    2013-04-01

    Meteorological and hydrological extremes (MHEs) cause great material damage or even loss of human lives in the present time, similarly as it was in the past. In the Czech Lands (recently the Czech Republic), systematic meteorological and hydrological observations started generally in the latter half of the 19th century. Therefore, in order to create long-term series of such extremes, it is necessary to search for other sources of information. Different types of documentary evidence are used in historical climatology and hydrology to find such information. Some of them are related to records connected with taxation system. The taxation system in Moravia allowed farmers to request tax relief if their crops have been damaged by MHEs. The corresponding documents contain information about the type of extreme event and the date of its occurrence; often also impacts on crops or land may be derived. The nature of events leading to damage include particularly hailstorms, torrential rain, flash floods, floods (in regions along larger rivers), less frequently windstorms, late frosts and in some cases also information about droughts or extreme snow depths. However, the results obtained are influenced by uncertainties related to taxation records - their temporal and spatial incompleteness, limitation of the MHEs occurrence in the period of main agricultural work (May-August) and the purpose for which they were originally collected (primarily tax alleviation, i.e. information about MHEs was of secondary importance). All these aspects related to the study of MHEs from taxation records are demonstrated for five estates (Bítov, Budkov, Jemnice with Staré Hobzí, Nové Syrovice and Uherčice) in the south-western part of Moravia for the 18th-19th centuries. The analysis shows importance of taxation records for the study of past MHEs as well as great potential for their use.

  16. Extreme inflow events and synoptic forcing in Sydney catchments

    International Nuclear Information System (INIS)

    Pepler, Acacia S; Rakich, Clinton S

    2010-01-01

    The Sydney catchment region encompasses over 16,000km 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.

  17. Characterization and prediction of extreme events in turbulence

    Science.gov (United States)

    Fonda, Enrico; Iyer, Kartik P.; Sreenivasan, Katepalli R.

    2017-11-01

    Extreme events in Nature such as tornadoes, large floods and strong earthquakes are rare but can have devastating consequences. The predictability of these events is very limited at present. Extreme events in turbulence are the very large events in small scales that are intermittent in character. We examine events in energy dissipation rate and enstrophy which are several tens to hundreds to thousands of times the mean value. To this end we use our DNS database of homogeneous and isotropic turbulence with Taylor Reynolds numbers spanning a decade, computed with different small scale resolutions and different box sizes, and study the predictability of these events using machine learning. We start with an aggressive data augmentation to virtually increase the number of these rare events by two orders of magnitude and train a deep convolutional neural network to predict their occurrence in an independent data set. The goal of the work is to explore whether extreme events can be predicted with greater assurance than can be done by conventional methods (e.g., D.A. Donzis & K.R. Sreenivasan, J. Fluid Mech. 647, 13-26, 2010).

  18. 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...

  19. Extreme Space Weather Events: From Cradle to Grave

    Science.gov (United States)

    Riley, Pete; Baker, Dan; Liu, Ying D.; Verronen, Pekka; Singer, Howard; Güdel, Manuel

    2018-02-01

    Extreme space weather events, while rare, can have a substantial impact on our technologically-dependent society. And, although such events have only occasionally been observed, through careful analysis of a wealth of space-based and ground-based observations, historical records, and extrapolations from more moderate events, we have developed a basic picture of the components required to produce them. Several key issues, however, remain unresolved. For example, what limits are imposed on the maximum size of such events? What are the likely societal consequences of a so-called "100-year" solar storm? In this review, we summarize our current scientific understanding about extreme space weather events as we follow several examples from the Sun, through the solar corona and inner heliosphere, across the magnetospheric boundary, into the ionosphere and atmosphere, into the Earth's lithosphere, and, finally, its impact on man-made structures and activities, such as spacecraft, GPS signals, radio communication, and the electric power grid. We describe preliminary attempts to provide probabilistic forecasts of extreme space weather phenomena, and we conclude by identifying several key areas that must be addressed if we are better able to understand, and, ultimately, predict extreme space weather events.

  20. Observed and simulated hydrologic response for a first-order catchment during extreme rainfall 3 years after wildfire disturbance

    Science.gov (United States)

    Ebel, Brian A.; Rengers, Francis K.; Tucker, Gregory E.

    2016-01-01

    Hydrologic response to extreme rainfall in disturbed landscapes is poorly understood because of the paucity of measurements. A unique opportunity presented itself when extreme rainfall in September 2013 fell on a headwater catchment (i.e., soil-hydraulic properties, soil saturation from subsurface sensors, and estimated peak runoff during the extreme rainfall with numerical simulations of runoff generation and subsurface hydrologic response during this event. The simulations were used to explore differences in runoff generation between the wildfire-affected headwater catchment, a simulated unburned case, and for uniform versus spatially variable parameterizations of soil-hydraulic properties that affect infiltration and runoff generation in burned landscapes. Despite 3 years of elapsed time since the 2010 wildfire, observations and simulations pointed to substantial surface runoff generation in the wildfire-affected headwater catchment by the infiltration-excess mechanism while no surface runoff was generated in the unburned case. The surface runoff generation was the result of incomplete recovery of soil-hydraulic properties in the burned area, suggesting recovery takes longer than 3 years. Moreover, spatially variable soil-hydraulic property parameterizations produced longer duration but lower peak-flow infiltration-excess runoff, compared to uniform parameterization, which may have important hillslope sediment export and geomorphologic implications during long duration, extreme rainfall. The majority of the simulated surface runoff in the spatially variable cases came from connected near-channel contributing areas, which was a substantially smaller contributing area than the uniform simulations.

  1. Laws of small numbers extremes and rare events

    CERN Document Server

    Falk, Michael; Reiss, Rolf-Dieter

    2011-01-01

    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. In this third edition, the dramatic change of focus of extreme value theory has been taken into account: from concentrating on maxima of observations it has shifted to l

  2. Spatio-Temporal Patterns of the 2010–2015 Extreme Hydrological Drought across the Central Andes, Argentina

    Directory of Open Access Journals (Sweden)

    Juan Antonio Rivera

    2017-08-01

    Full Text Available During the period 2010–2015, the semi-arid Central Andes in Argentina (CAA experienced one of the most severe and long-lasting hydrological droughts on record. Since the snowmelt is the most important source of water, the reduced snowfall over the mountains propagated the drought signal through the streamflows in the adjacent foothills east of the Andes ranges. Motivated by the widespread impacts on the socio-economic activities in the region, this study aims to characterize the recent hydrological drought in terms of streamflow deficits. Based on streamflow data from 20 basins, we used the standardized streamflow index (SSI to characterize hydrological droughts during the period 1971–2016. We found that the regional extent of the 2010–2015 hydrological drought was limited to the basins located north of 38° S, with mean duration of 67 months and maximum drought severity exhibiting a heterogeneous pattern in terms of spatial distribution and time of occurrence. The drought event reached extreme conditions in 14 of the 15 basins in the CAA, being record-breaking drought in six of the basins. This condition was likely driven by a cooling in the tropical Pacific Ocean resembling La Niña conditions, which generated a decrease in snowfall over the Andes due to suppressed frontal activity.

  3. Impacts of Extreme Events on Human Health. Chapter 4

    Science.gov (United States)

    Bell, Jesse E.; Herring, Stephanie C.; Jantarasami, Lesley; Adrianopoli, Carl; Benedict, Kaitlin; Conlon, Kathryn; Escobar, Vanessa; Hess, Jeremy; Luvall, Jeffrey; Garcia-Pando, Carlos Perez; hide

    2016-01-01

    Increased Exposure to Extreme Events Key Finding 1: Health impacts associated with climate-related changes in exposure to extreme events include death, injury, or illness; exacerbation of underlying medical conditions; and adverse effects on mental health[High Confidence]. Climate change will increase exposure risk in some regions of the United States due to projected increases in the frequency and/or intensity of drought, wildfires, and flooding related to extreme precipitation and hurricanes [Medium Confidence].Disruption of Essential Infrastructure Key Finding 2: Many types of extreme events related to climate change cause disruption of infrastructure, including power, water, transportation, and communication systems, that are essential to maintaining access to health care and emergency response services and safeguarding human health [High Confidence].Vulnerability to Coastal Flooding Key Finding 3: Coastal populations with greater vulnerability to health impacts from coastal flooding include persons with disabilities or other access and functional needs, certain populations of color, older adults, pregnant women and children, low-income populations, and some occupational groups [High Confidence].Climate change will increase exposure risk to coastal flooding due to increases in extreme precipitation and in hurricane intensity and rainfall rates, as well as sea level rise and the resulting increases in storm surge.

  4. Climate Change : Behavioral Responses from Extreme Events and Delayed Damages

    NARCIS (Netherlands)

    Ghidoni, Riccardo; Calzolari, G.; Casari, Marco

    2017-01-01

    Understanding how to sustain cooperation in the climate change global dilemma is crucial to mitigate its harmful consequences. Damages from climate change typically occurs after long delays and can take the form of more frequent realizations of extreme and random events. These features generate a

  5. Climate change : Behavioral responses from extreme events and delayed damages

    NARCIS (Netherlands)

    Ghidoni, Riccardo; Calzolari, Giacomo; Casari, Marco

    2017-01-01

    Understanding how to sustain cooperation in the climate change global dilemma is crucial to mitigate its harmful consequences. Damages from climate change typically occur after long delays and can take the form of more frequent realizations of extreme and random events. These features generate a

  6. 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.

  7. Influence of climate variability versus change at multi-decadal time scales on hydrological extremes

    Science.gov (United States)

    Willems, Patrick

    2014-05-01

    Recent studies have shown that rainfall and hydrological extremes do not randomly occur in time, but are subject to multidecadal oscillations. In addition to these oscillations, there are temporal trends due to climate change. Design statistics, such as intensity-duration-frequency (IDF) for extreme rainfall or flow-duration-frequency (QDF) relationships, are affected by both types of temporal changes (short term and long term). This presentation discusses these changes, how they influence water engineering design and decision making, and how this influence can be assessed and taken into account in practice. The multidecadal oscillations in rainfall and hydrological extremes were studied based on a technique for the identification and analysis of changes in extreme quantiles. The statistical significance of the oscillations was evaluated by means of a non-parametric bootstrapping method. Oscillations in large scale atmospheric circulation were identified as the main drivers for the temporal oscillations in rainfall and hydrological extremes. They also explain why spatial phase shifts (e.g. north-south variations in Europe) exist between the oscillation highs and lows. Next to the multidecadal climate oscillations, several stations show trends during the most recent decades, which may be attributed to climate change as a result of anthropogenic global warming. Such attribution to anthropogenic global warming is, however, uncertain. It can be done based on simulation results with climate models, but it is shown that the climate model results are too uncertain to enable a clear attribution. Water engineering design statistics, such as extreme rainfall IDF or peak or low flow QDF statistics, obviously are influenced by these temporal variations (oscillations, trends). It is shown in the paper, based on the Brussels 10-minutes rainfall data, that rainfall design values may be about 20% biased or different when based on short rainfall series of 10 to 15 years length, and

  8. Extreme flood events in the Bolivian Amazon wetlands

    Directory of Open Access Journals (Sweden)

    A. Ovando

    2016-03-01

    Full Text Available Study region: The Amazonian wetlands of Bolivia, known as the Llanos de Moxos, are believed to play a crucial role in regulating the upper Madeira hydrological cycle, the most important southern tributary of the Amazon River. Because the area is vast and sparsely populated, the hydrological functioning of the wetlands is poorly known. Study focus: We analyzed the hydrometeorological configurations that led to the major floods of 2007, 2008 and 2014. These data, together with flood mapping derived from remote sensing images, were used to understand the dynamics of the Llanos during the three flood events. New hydrological insights for the region: The results showed that large floods are the result of the superimposition of flood waves from major sub-basins of the region. As a previous study suggested, the dynamics of the floods are controlled by an exogenous process, created by the flood wave originating in the Andes piedmont that travels through the Mamoré River; and by an endogenous process, which is the runoff originating in the Llanos. Our study showed that the first process is evident only at the initial phase of the floods, and although important for attenuating the rising flood wave, it is of lesser importance compared to the endogenous process. We conclude that the endogenous process controls the magnitude and duration of major floods. Keywords: Flood dynamics, Wetlands, Remote sensing, Llanos de Moxos

  9. Human impact parameterizations in global hydrological models improve estimates of monthly discharges and hydrological extremes: a multi-model validation study

    NARCIS (Netherlands)

    Veldkamp, T I E; Zhao, F; Ward, P J; Moel, H de; Aerts, J C J H; Schmied, H Müller; Portmann, F T; Masaki, Y; Pokhrel, Y; Liu, X; Satoh, Yusuke; Gerten, Dieter; Gosling, S N; Zaherpour, J; Wada, Yoshihide

    2018-01-01

    Human activity has a profound influence on river discharges, hydrological extremes and water-related hazards. In this study, we compare the results of five state-of-the-art global hydrological models (GHMs) with observations to examine the role of human impact parameterizations (HIP) in the

  10. Combining geomorphic and documentary flood evidence to reconstruct extreme events in Mediterranean basins

    Science.gov (United States)

    Thorndycraft, V. R.; Benito, G.; Barriendos, M.; Rico, M.; Sánchez-Moya, Y.; Sopeña, A.; Casas, A.

    2009-09-01

    Palaeoflood hydrology is the reconstruction of flood magnitude and frequency using geomorphological flood evidence and is particularly valuable for extending the record of extreme floods prior to the availability of instrumental data series. This paper will provide a review of recent developments in palaeoflood hydrology and will be presented in three parts: 1) an overview of the key methodological approaches used in palaeoflood hydrology and the use of historical documentary evidence for reconstructing extreme events; 2) a summary of the Llobregat River palaeoflood case study (Catalonia, NE Spain); and 3) analysis of the AD 1617 flood and its impacts across Catalonia (including the rivers Llobregat, Ter and Segre). The key findings of the Llobregat case study were that at least eight floods occurred with discharges significantly larger than events recorded in the instrumental record, for example at the Pont de Vilomara study reach the palaeodischarges of these events were 3700-4300 m3/s compared to the 1971 flood, the largest on record, of 2300 m3/s. Five of these floods were dated to the last 3000 years and the three events directly dated by radiocarbon all occurred during cold phases of global climate. Comparison of the palaeoflood record with documentary evidence indicated that one flood, radiocarbon dated to cal. AD 1540-1670, was likely to be the AD 1617 event, the largest flood of the last 700 years. Historical records indicate that this event was caused by rainfall occurring from the 2nd to 6th November and the resultant flooding caused widespread socio-economic impacts including the destruction of at least 389 houses, 22 bridges and 17 water mills. Discharges estimated from palaeoflood records and historical flood marks indicate that the Llobregat (4680 m3/s) and Ter (2700-4500 m3/s) rivers witnessed extreme discharges in comparison to observed floods in the instrumental record (2300 and 2350 m3/s, respectively); whilst further east in the Segre River

  11. Characterization of extreme flood and drought events in Singapore and investigation of their relationships with ENSO

    Science.gov (United States)

    Li, Xin; Babovic, Vladan

    2016-04-01

    Flood and drought are hydrologic extreme events that have significant impact on human and natural systems. Characterization of flood and drought in terms of their start, duration and strength, and investigation of the impact of natural climate variability (i.e., ENSO) and anthropogenic climate change on them can help decision makers to facilitate adaptions to mitigate potential enormous economic costs. To date, numerous studies in this area have been conducted, however, they are primarily focused on extra-tropical regions. Therefore, this study presented a detailed framework to characterize flood and drought events in a tropical urban city-state (i.e., Singapore), based on daily data from 26 precipitation stations. Flood and drought events are extracted from standardized precipitation anomalies from monthly to seasonal time scales. Frequency, duration and magnitude of flood and drought at all the stations are analyzed based on crossing theory. In addition, spatial variation of flood and drought characteristics in Singapore is investigated using ordinary kriging method. Lastly, the impact of ENSO condition on flood and drought characteristics is analyzed using regional regression method. The results show that Singapore can be prone to extreme flood and drought events at both monthly and seasonal time scales. ENSO has significant influence on flood and drought characteristics in Singapore, but mainly during the South West Monsoon season. During the El Niño phase, drought can become more extreme. The results have implications for water management practices in Singapore.

  12. Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes.

    Directory of Open Access Journals (Sweden)

    A F Lutz

    Full Text Available The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically downscaled CMIP5 General Circulation Model outputs for RCP4.5 and RCP8.5 to force a cryospheric-hydrological model and generate transient hydrological projections for the entire 21st century for the upper Indus basin. Three methodological advances are introduced: (i A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used. (ii The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance. (iii An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes. The analysis of the results focuses on changes in sources of runoff, seasonality and hydrological extremes. We conclude that the future of the upper Indus basin's water availability is highly uncertain in the long run, mainly due to the large spread in the future precipitation projections. Despite large uncertainties in the future climate and long-term water availability, basin-wide patterns and trends of seasonal shifts in water availability are consistent across climate change scenarios. Most prominent is the attenuation of the annual hydrograph and shift from summer peak flow towards the other seasons for most ensemble members. In addition there are distinct spatial patterns in the response that relate to monsoon influence and the importance of meltwater. Analysis of future hydrological extremes reveals that increases in intensity and frequency of extreme discharges are very likely for most of the upper Indus basin and most ensemble members.

  13. Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes

    Science.gov (United States)

    Immerzeel, W. W.; Kraaijenbrink, P. D. A.; Shrestha, A. B.; Bierkens, M. F. P.

    2016-01-01

    The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically downscaled CMIP5 General Circulation Model outputs for RCP4.5 and RCP8.5 to force a cryospheric-hydrological model and generate transient hydrological projections for the entire 21st century for the upper Indus basin. Three methodological advances are introduced: (i) A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used. (ii) The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance. (iii) An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes. The analysis of the results focuses on changes in sources of runoff, seasonality and hydrological extremes. We conclude that the future of the upper Indus basin’s water availability is highly uncertain in the long run, mainly due to the large spread in the future precipitation projections. Despite large uncertainties in the future climate and long-term water availability, basin-wide patterns and trends of seasonal shifts in water availability are consistent across climate change scenarios. Most prominent is the attenuation of the annual hydrograph and shift from summer peak flow towards the other seasons for most ensemble members. In addition there are distinct spatial patterns in the response that relate to monsoon influence and the importance of meltwater. Analysis of future hydrological extremes reveals that increases in intensity and frequency of extreme discharges are very likely for most of the upper Indus basin and most ensemble members. PMID:27828994

  14. Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes.

    Science.gov (United States)

    Lutz, A F; Immerzeel, W W; Kraaijenbrink, P D A; Shrestha, A B; Bierkens, M F P

    2016-01-01

    The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically downscaled CMIP5 General Circulation Model outputs for RCP4.5 and RCP8.5 to force a cryospheric-hydrological model and generate transient hydrological projections for the entire 21st century for the upper Indus basin. Three methodological advances are introduced: (i) A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used. (ii) The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance. (iii) An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes. The analysis of the results focuses on changes in sources of runoff, seasonality and hydrological extremes. We conclude that the future of the upper Indus basin's water availability is highly uncertain in the long run, mainly due to the large spread in the future precipitation projections. Despite large uncertainties in the future climate and long-term water availability, basin-wide patterns and trends of seasonal shifts in water availability are consistent across climate change scenarios. Most prominent is the attenuation of the annual hydrograph and shift from summer peak flow towards the other seasons for most ensemble members. In addition there are distinct spatial patterns in the response that relate to monsoon influence and the importance of meltwater. Analysis of future hydrological extremes reveals that increases in intensity and frequency of extreme discharges are very likely for most of the upper Indus basin and most ensemble members.

  15. Statistical analysis of extreme values from insurance, finance, hydrology and other fields

    CERN Document Server

    Reiss, Rolf-Dieter

    1997-01-01

    The statistical analysis of extreme data is important for various disciplines, including hydrology, insurance, finance, engineering and environmental sciences. This book provides a self-contained introduction to the parametric modeling, exploratory analysis and statistical interference for extreme values. The entire text of this third edition has been thoroughly updated and rearranged to meet the new requirements. Additional sections and chapters, elaborated on more than 100 pages, are particularly concerned with topics like dependencies, the conditional analysis and the multivariate modeling of extreme data. Parts I–III about the basic extreme value methodology remain unchanged to some larger extent, yet notable are, e.g., the new sections about "An Overview of Reduced-Bias Estimation" (co-authored by M.I. Gomes), "The Spectral Decomposition Methodology", and "About Tail Independence" (co-authored by M. Frick), and the new chapter about "Extreme Value Statistics of Dependent Random Variables" (co-authored ...

  16. Diagnosing causes of extreme aerosol optical depth events

    Science.gov (United States)

    Bernstein, D. N.; Sullivan, R.; Crippa, P.; Thota, A.; Pryor, S. C.

    2017-12-01

    Aerosol burdens and optical properties exhibit substantial spatiotemporal variability, and simulation of current and possible future aerosol burdens and characteristics exhibits relatively high uncertainty due to uncertainties in emission estimates and in chemical and physical processes associated with aerosol formation, dynamics and removal. We report research designed to improve understanding of the causes and characteristics of extreme aerosol optical depth (AOD) at the regional scale, and diagnose and attribute model skill in simulating these events. Extreme AOD events over the US Midwest are selected by identifying all dates on which AOD in a MERRA-2 reanalysis grid cell exceeds the local seasonally computed 90th percentile (p90) value during 2004-2016 and then finding the dates on which the highest number of grid cells exceed their local p90. MODIS AOD data are subsequently used to exclude events dominated by wildfires. MERRA-2 data are also analyzed within a synoptic classification to determine in what ways the extreme AOD events are atypical and to identify possible meteorological `finger-prints' that can be detected in regional climate model simulations of future climate states to project possible changes in the occurrence of extreme AOD. Then WRF-Chem v3.6 is applied at 12-km resolution and regridded to the MERRA-2 resolution over eastern North America to quantify model performance, and also evaluated using in situ measurements of columnar AOD (AERONET) and near-surface PM2.5 (US EPA). Finally the sensitivity to (i) spin-up time (including procedure used to spin-up the chemistry), (ii) modal versus sectional aerosol schemes, (iii) meteorological nudging, (iv) chemistry initial and boundary conditions, and (v) anthropogenic emissions is quantified. Despite recent declines in mean AOD, supraregional (> 1000 km) extreme AOD events continue to occur. During these events AOD exceeds 0.6 in many Midwestern grid cells for multiple consecutive days. In all

  17. 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

  18. 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

  19. 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.

  20. Expected impacts of climate change on extreme climate events

    International Nuclear Information System (INIS)

    Planton, S.; Deque, M.; Chauvin, F.; Terray, L.

    2008-01-01

    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)

  1. 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...

  2. 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.

  3. Adaptation to extreme climate events at a regional scale

    OpenAIRE

    Hoffmann, Christin

    2017-01-01

    A significant increase of the frequency, the intensity and the duration of extreme climate events in Switzerland induces the need to find a strategy to deal with the damages they cause. For more than two decades, mitigation has been the main objective of climate policy. However, due to already high atmospheric carbon concentrations and the inertia of the climate system, climate change is unavoidable to some degree, even if today’s emissions were almost completely cut back. Along with the high...

  4. Water shortages and extreme events: a call for research.

    Science.gov (United States)

    Carmichael, Catriona; Odams, Sue; Murray, Virginia; Sellick, Matthew; Colbourne, Jeni

    2013-09-01

    Water shortages as a result of extreme weather events, such as flooding and severe cold, have the potential to affect significant numbers of people. Therefore, the need to build robust, coordinated plans based on scientific evidence is crucial. The literature review outlined in this short communication was conducted as part of a joint Drinking Water Inspectorate and Health Protection Agency (now Public Health England) report which aimed to review the scientific evidence base on extreme events, water shortages and the resulting health impacts. A systematic literature review was undertaken to identify published literature from both peer-reviewed and grey literature sources. The retrieved literature was then assessed using the Scottish Intercollegiate Guidelines Network quality assessment. The authors found very few scientific studies. However, a great deal of valuable grey literature was retrieved and used by the research team. In total, six main themes of importance that were identified by the review and discussed included health impacts, water quantity and quality, alternative supplies, vulnerable groups, communication with those affected and the emergency response. The authors conclude that more research needs to be conducted on health impacts and extreme events water shortages in order to build the future knowledge base and development of resilience.

  5. Invited Article: Visualisation of extreme value events in optical communications

    Science.gov (United States)

    Derevyanko, Stanislav; Redyuk, Alexey; Vergeles, Sergey; Turitsyn, Sergei

    2018-06-01

    Fluctuations of a temporal signal propagating along long-haul transoceanic scale fiber links can be visualised in the spatio-temporal domain drawing visual analogy with ocean waves. Substantial overlapping of information symbols or use of multi-frequency signals leads to strong statistical deviations of local peak power from an average signal power level. We consider long-haul optical communication systems from this unusual angle, treating them as physical systems with a huge number of random statistical events, including extreme value fluctuations that potentially might affect the quality of data transmission. We apply the well-established concepts of adaptive wavefront shaping used in imaging through turbid medium to detect the detrimental phase modulated sequences in optical communications that can cause extreme power outages (rare optical waves of ultra-high amplitude) during propagation down the ultra-long fiber line. We illustrate the concept by a theoretical analysis of rare events of high-intensity fluctuations—optical freak waves, taking as an example an increasingly popular optical frequency division multiplexing data format where the problem of high peak to average power ratio is the most acute. We also show how such short living extreme value spikes in the optical data streams are affected by nonlinearity and demonstrate the negative impact of such events on the system performance.

  6. 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.

  7. Palaeoflood hydrology in Europe: towards a better understanding of extreme floods

    Science.gov (United States)

    Benito, G.; Thorndycraft, V. R.; Rico, M.; Sheffer, N.; Enzel, Y.

    2003-04-01

    Floods are the most common natural disasters in Europe and, in terms of economic damage, costs are increasing spectacularly with time. Flood risk assessment associated with extreme floods is difficult due to the scarcity of hydrological measurements, that rarely go beyond 1000 years, which is clearly not sufficient for flood management in urban and industrial areas. Besides the use of conventional hydrologic data, the pre-instrumental record can be completed from palaeoflood hydrology or from documentary flood information, or through the combined use of both these tools. Recent developments of palaeoflood hydrology in Europe provide (1) major improvements in flood risk assessment, and (2) a better understanding of long-term flood-climate relationships. Palaeoflood hydrology has been successfully applied in large, medium rivers as well as small ungauged mountain drainage basins. Long-term palaeoflood records from Spain and France show that recent extraordinary flooding (causing huge economic damages) are not the largest ones, but that similar or even greater floods occurred several times in the past. In addition, clusters of floods coinciding in time at several European rivers point out to climatic factors as responsible mechanisms, although in recent time flood magnitude can be magnified by increasing human activity.

  8. Autochthonous Chikungunya Transmission and Extreme Climate Events in Southern France.

    Science.gov (United States)

    Roiz, David; Boussès, Philippe; Simard, Frédéric; Paupy, Christophe; Fontenille, Didier

    2015-06-01

    Extreme precipitation events are increasing as a result of ongoing global warming, but controversy surrounds the relationship between flooding and mosquito-borne diseases. A common view among the scientific community and public health officers is that heavy rainfalls have a flushing effect on breeding sites, which negatively affects vector populations, thereby diminishing disease transmission. During 2014 in Montpellier, France, there were at least 11 autochthonous cases of chikungunya caused by the invasive tiger mosquito Aedes albopictus in the vicinity of an imported case. We show that an extreme rainfall event increased and extended the abundance of the disease vector Ae. albopictus, hence the period of autochthonous transmission of chikungunya. We report results from close monitoring of the adult and egg population of the chikungunya vector Ae. albopictus through weekly sampling over the entire mosquito breeding season, which revealed an unexpected pattern. Statistical analysis of the seasonal dynamics of female abundance in relation to climatic factors showed that these relationships changed after the heavy rainfall event. Before the inundations, accumulated temperatures are the most important variable predicting Ae. albopictus seasonal dynamics. However, after the inundations, accumulated rainfall over the 4 weeks prior to capture predicts the seasonal dynamics of this species and extension of the transmission period. Our empirical data suggests that heavy rainfall events did increase the risk of arbovirus transmission in Southern France in 2014 by favouring a rapid rise in abundance of vector mosquitoes. Further studies should now confirm these results in different ecological contexts, so that the impact of global change and extreme climatic events on mosquito population dynamics and the risk of disease transmission can be adequately understood.

  9. Climate Extreme Events over Northern Eurasia in Changing Climate

    Science.gov (United States)

    Bulygina, O.; Korshunova, N. N.; Razuvaev, V. N.; Groisman, P. Y.

    2014-12-01

    During the period of widespread instrumental observations in Northern Eurasia, the annual surface air temperature has increased by 1.5°C. Close to the north in the Arctic Ocean, the late summer sea ice extent has decreased by 40% providing a near-infinite source of water vapor for the dry Arctic atmosphere in the early cold season months. The contemporary sea ice changes are especially visible in the Eastern Hemisphere All these factors affect the change extreme events. Daily and sub-daily data of 940 stations to analyze variations in the space time distribution of extreme temperatures, precipitation, and wind over Russia were used. Changing in number of days with thaw over Russia was described. The total seasonal numbers of days, when daily surface air temperatures (wind, precipitation) were found to be above (below) selected thresholds, were used as indices of climate extremes. Changing in difference between maximum and minimum temperature (DTR) may produce a variety of effects on biological systems. All values falling within the intervals ranged from the lowest percentile to the 5th percentile and from the 95th percentile to the highest percentile for the time period of interest were considered as daily extremes. The number of days, N, when daily temperatures (wind, precipitation, DTR) were within the above mentioned intervals, was determined for the seasons of each year. Linear trends in the number of days were calculated for each station and for quasi-homogeneous climatic regions. Regional analysis of extreme events was carried out using quasi-homogeneous climatic regions. Maps (climatology, trends) are presented mostly for visualization purposes. Differences in regional characteristics of extreme events are accounted for over a large extent of the Russian territory and variety of its physical and geographical conditions. The number of days with maximum temperatures higher than the 95% percentile has increased in most of Russia and decreased in Siberia in

  10. Understanding extreme rainfall events in Australia through historical data

    Science.gov (United States)

    Ashcroft, Linden; Karoly, David John

    2016-04-01

    Historical climate data recovery is still an emerging field in the Australian region. The majority of Australia's instrumental climate analyses begin in 1900 for rainfall and 1910 for temperature, particularly those focussed on extreme event analysis. This data sparsity for the past in turn limits our understanding of long-term climate variability, constraining efforts to predict the impact of future climate change. To address this need for improved historical data in Australia, a new network of recovered climate observations has recently been developed, centred on the highly populated southeastern Australian region (Ashcroft et al., 2014a, 2014b). The dataset includes observations from more than 39 published and unpublished sources and extends from British settlement in 1788 to the formation of the Australian Bureau of Meteorology in 1908. Many of these historical sources provide daily temperature and rainfall information, providing an opportunity to improve understanding of the multidecadal variability of Australia's extreme events. In this study we combine the historical data for three major Australian cities - Melbourne, Sydney and Adelaide - with modern observations to examine extreme rainfall variability over the past 174 years (1839-2013). We first explore two case studies, combining instrumental and documentary evidence to support the occurrence of severe storms in Sydney in 1841 and 1844. These events appear to be at least as extreme as Sydney's modern 24-hour rainfall record. Next we use a suite of rainfall indices to assess the long-term variability of rainfall in southeastern Australia. In particular, we focus on the stationarity of the teleconnection between the El Niño-Southern Oscillation (ENSO) phenomenon and extreme rainfall events. Using ENSO reconstructions derived from both palaeoclimatic and documentary sources, we determine the historical relationship between extreme rainfall in southeastern Australia and ENSO, and examine whether or not this

  11. Correlation between Space and Atmospheric March 2012 Extreme Events

    Science.gov (United States)

    Anagnostopoulos, Georgios C.

    2015-04-01

    Previous studies have provided statistical evidence of a solar cycle correlation between space weather and meteorological phenomena. In this study we present a case study, the March 2012 events, with a strong evidence of such a correlation between space and atmospheric extreme events. March 2012 phenomena, beside a great CME (March 7) and a following superstorm, has been most known in the scientific community as well as in the public from the historic heat wave in USA. This event was not anticipated by solely atmospheric models (called a "black swan event":http://www.esrl.noaa.gov/psd/csi/events/2012/marchheatwave/anticipation.html). Furthermore, various extreme phenomena as high temperatures, intense rainfalls and ice extent at middle and high latitudes followed the March 7, 2012 CME all over the globe (USA, Europe, Australia, Antartic), while unusual measurements of various atmospheric and ionospheric quantities were observed by a series of satellites (TIMED, MODIS, NOAA etc.) In this study we concentrate to (a) the unusual high maximum of temperature in north-east USA (highest values since 1910) and (b) intense winds, rainfalls and fluctuating (>1500 V/m) geolectric fields in South East Europe (Greece). These events were observed almost simultaneously with geomagnetic storms and unusual radiation belt electron precipitation (RBEP) events on days 6-9, 10-12 and 26-28.3.2012 (two CMEs and one CIR). The most striking result is the time coincidence of variations of several space and meteorological measurements, which, for instance, most probably suggests a direct influence of the RBEP on the intense rainfalls observed in Greece. It is also possible that the RBEP at polar latitudes was responsible for the positive North Atlantic Oscillation effect evaluated at those times, which contributed to the global middle and high latitude weather variations. Our study provides an example of possible space weather utility to the atmospheric models, and, therefore, to the

  12. Assessment of the potential forecasting skill of a global hydrological model in reproducing the occurrence of monthly flow extremes

    Directory of Open Access Journals (Sweden)

    N. Candogan Yossef

    2012-11-01

    Full Text Available As an initial step in assessing the prospect of using global hydrological models (GHMs for hydrological forecasting, this study investigates the skill of the GHM PCR-GLOBWB in reproducing the occurrence of past extremes in monthly discharge on a global scale. Global terrestrial hydrology from 1958 until 2001 is simulated by forcing PCR-GLOBWB with daily meteorological data obtained by downscaling the CRU dataset to daily fields using the ERA-40 reanalysis. Simulated discharge values are compared with observed monthly streamflow records for a selection of 20 large river basins that represent all continents and a wide range of climatic zones.

    We assess model skill in three ways all of which contribute different information on the potential forecasting skill of a GHM. First, the general skill of the model in reproducing hydrographs is evaluated. Second, model skill in reproducing significantly higher and lower flows than the monthly normals is assessed in terms of skill scores used for forecasts of categorical events. Third, model skill in reproducing flood and drought events is assessed by constructing binary contingency tables for floods and droughts for each basin. The skill is then compared to that of a simple estimation of discharge from the water balance (PE.

    The results show that the model has skill in all three types of assessments. After bias correction the model skill in simulating hydrographs is improved considerably. For most basins it is higher than that of the climatology. The skill is highest in reproducing monthly anomalies. The model also has skill in reproducing floods and droughts, with a markedly higher skill in floods. The model skill far exceeds that of the water balance estimate. We conclude that the prospect for using PCR-GLOBWB for monthly and seasonal forecasting of the occurrence of hydrological extremes is positive. We argue that this conclusion applies equally to other similar GHMs and

  13. 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

  14. 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.

  15. Intraoperative adverse events associated with extremely preterm cesarean deliveries.

    Science.gov (United States)

    Bertholdt, Charline; Menard, Sophie; Delorme, Pierre; Lamau, Marie-Charlotte; Goffinet, François; Le Ray, Camille

    2018-05-01

    At the same time as survival is increasing among premature babies born before 26 weeks of gestation, the rates of cesarean deliveries before 26 weeks is also rising. Our purpose was to compare the frequency of intraoperative adverse events during cesarean deliveries in two gestational age groups: 24-25 weeks and 26-27 weeks. This single-center retrospective cohort study included all women with cesarean deliveries performed before 28 +0 weeks from 2007 through 2015. It compared the frequency of intraoperative adverse events between two groups: those at 24-25 weeks of gestation and at 26-27 weeks. Intraoperative adverse events were a classical incision, transplacental incision, difficulty in fetal extraction (explicitly mentioned in the surgical report), postpartum hemorrhage (≥500 mL of blood loss), and injury to internal organs. A composite outcome including at least one of these events enabled us to analyze the risk factors for intraoperative adverse events with univariate and multivariable analysis. Stratified analyses by the indication for the cesarean were performed. We compared 74 cesarean deliveries at 24-25 weeks of gestation and 214 at 26-27 weeks. Intraoperative adverse events occurred at higher rates in the 24-25-week group (63.5 vs. 30.8%, p cesarean. These results should help obstetricians and women making decisions about cesarean deliveries at these extremely low gestational ages. © 2018 Nordic Federation of Societies of Obstetrics and Gynecology.

  16. An impact of deforestation by extreme weather events on Sphagnum peatland ecosystem

    Science.gov (United States)

    Slowinski, M. M.; Łuców, D.; Kołaczek, P.; Tjallingii, R.; Lane, C. S.; Slowinska, S.; Tyszkowski, S.; Łokas, E.; Theuerkauf, M.; Brauer, A.; Lamentowicz, M.

    2017-12-01

    An increase in extreme weather phenomena has been observed over the last decades as a result of global climate warming. Terrestrial ecosystems are influenced by different types of disturbances such as e.g. deforestation, land-use, fragmentation, fire, floods or storms. Disturbance triggers may be natural or anthropogenic, but usually we observe negative feedback loops and interconnected causal factors. Here we investigate the effects of a tornado event on the peatland ecosystem of the Tuchola Pinewoods, Northern Poland. Deforestation by tornado events can cause severe perturbations of the hydrology and erosion that, in turn, affects adjacent lakes and peatlands. Martwe peatland provide an exceptional opportunity to study the impact of such extreme events, as it was struck by a tornado in 2012. Our research is focused on lake-peatland ecosystems that were directly affected by this tornado, and we consider the general transformation of the vegetation (mainly forests) over the last 150 years. Extensive clearing of the forest occurred in the nineteenth century due to human activity, and we compare this with the impact of the 2012 tornado. Accurate reconstructions will rely on a broad range of palaeoecological techniques such as pollen, macro-remains and testate amoebae, but also on geochemistry, i.e. μXRF scanning. The chronology of the records is based on 210Pb and radiocarbon dating and will incorporate correlations using (crypto)tephra markers of the Eyjafjöll (2010) and Askja (1875) eruptions. We expect to observe that disturbance (tornado-induced deforestation) affects the short-term changes in peatland productivity and biodiversity, through a cascading "top-down" effect. This research addresses the emerging issue of the impact of extreme phenomena and more general climate changes on peatland ecosystems, which will potentially help to inform adaptations to the environmental consequences of extreme events in the future. This project is funded by the Polish

  17. 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.

  18. Reproducing an extreme flood with uncertain post-event information

    Directory of Open Access Journals (Sweden)

    D. Fuentes-Andino

    2017-07-01

    Full Text Available Studies for the prevention and mitigation of floods require information on discharge and extent of inundation, commonly unavailable or uncertain, especially during extreme events. This study was initiated by the devastating flood in Tegucigalpa, the capital of Honduras, when Hurricane Mitch struck the city. In this study we hypothesized that it is possible to estimate, in a trustworthy way considering large data uncertainties, this extreme 1998 flood discharge and the extent of the inundations that followed from a combination of models and post-event measured data. Post-event data collected in 2000 and 2001 were used to estimate discharge peaks, times of peak, and high-water marks. These data were used in combination with rain data from two gauges to drive and constrain a combination of well-known modelling tools: TOPMODEL, Muskingum–Cunge–Todini routing, and the LISFLOOD-FP hydraulic model. Simulations were performed within the generalized likelihood uncertainty estimation (GLUE uncertainty-analysis framework. The model combination predicted peak discharge, times of peaks, and more than 90 % of the observed high-water marks within the uncertainty bounds of the evaluation data. This allowed an inundation likelihood map to be produced. Observed high-water marks could not be reproduced at a few locations on the floodplain. Identifications of these locations are useful to improve model set-up, model structure, or post-event data-estimation methods. Rainfall data were of central importance in simulating the times of peak and results would be improved by a better spatial assessment of rainfall, e.g. from radar data or a denser rain-gauge network. Our study demonstrated that it was possible, considering the uncertainty in the post-event data, to reasonably reproduce the extreme Mitch flood in Tegucigalpa in spite of no hydrometric gauging during the event. The method proposed here can be part of a Bayesian framework in which more events

  19. Grid Frequency Extreme Event Analysis and Modeling: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Florita, Anthony R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Clark, Kara [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Folgueras, Maria [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wenger, Erin [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-01

    Sudden losses of generation or load can lead to instantaneous changes in electric grid frequency and voltage. Extreme frequency events pose a major threat to grid stability. As renewable energy sources supply power to grids in increasing proportions, it becomes increasingly important to examine when and why extreme events occur to prevent destabilization of the grid. To better understand frequency events, including extrema, historic data were analyzed to fit probability distribution functions to various frequency metrics. Results showed that a standard Cauchy distribution fit the difference between the frequency nadir and prefault frequency (f_(C-A)) metric well, a standard Cauchy distribution fit the settling frequency (f_B) metric well, and a standard normal distribution fit the difference between the settling frequency and frequency nadir (f_(B-C)) metric very well. Results were inconclusive for the frequency nadir (f_C) metric, meaning it likely has a more complex distribution than those tested. This probabilistic modeling should facilitate more realistic modeling of grid faults.

  20. Recent Extreme Marine Events at Southern Coast of Black Sea

    Science.gov (United States)

    Ozyurt Tarakcioglu, Gulizar; Cevdet Yalciner, Ahmet; Kirezci, Cagil; Baykal, Cuneyt; Gokhan Guler, Hasan; Erol, Onur; Zaytsev, Andrey; Kurkin, Andrey

    2015-04-01

    The utilization at the coastal areas of Black Sea basin has increased in the recent years with the projects such as large commercial ports, international transportation hubs, gas and petrol pipelines, touristic and recreational infrastructures both along surrounding shoreline. Although Black Sea is a closed basin, extreme storms and storm surges have also been observed with an increasing frequency in the recent years. Among those events, February 1999, March 2013 and September 2014 storms impacted Southern coast of Black sea have clearly shown that the increasing economic value at the coastal areas caused the increasing cost of damages and loss of property by natural hazards. The storm occurred on February 19-20, 1999 is one of the most destructive storm in the last decades. The 1999 event (1999 Southern Black sea storm) caused destruction at all harbors and coastal protection structures along the Black Sea coast of Turkey. The complete damage of the breakwater of Giresun Harbor and damage on the harbor structures and cargo handling equipment were the major impacts of the 1999 Southern Black sea storm. Similar coastal impact have also been observed during the September 24, 2014 storm at 500m East of Giresun harbor. Although there are considerable number of destructive storms observed at southern coast of Black sea recently, data on these events are limited and vastly scattered. In this study the list of recent extreme marine events at South coast of the Black sea compiled and related data such as wind speed, wave height, period, and type of damages are cataloged. Particular attention is focused on the 1999 and 2014 storm events. The meteorological and morphological characteristics which may be considered as the reasons of the generation and coastal amplification of these storms are discussed. ACKNOWLEDGEMENTS: This study is partly supported by Turkish Russian Joint Research Grant Program by TUBITAK (Turkey) and RFBR (Russia), and TUBITAK 213M534 Research Project.

  1. STATISTICAL MODELLING OF FDC AND RETURN PERIODS TO CHARACTERISE QDF AND DESIGN THRESHOLD OF HYDROLOGICAL EXTREMES

    Directory of Open Access Journals (Sweden)

    Charles Onyutha

    2012-01-01

    Full Text Available In this paper, firstly, flow duration curves (FDCs for hydrological extremes were calibrated for a range of aggregation levels and seasons to provide compressed statistical information for water resources management at selected temporal scales and seasons. Secondly, instead of the common approach of using return periods, T (years for deriving discharge duration frequency (QDF relationships, the method of using exceedance frequencies, E (% was introduced so as to provide answer to important question like, what is the streamflow at a given aggregation level and selected E (%? Thirdly, the concept of estimated design threshold (EDT was introduced and proposed for consideration in the risk analysis for design of water resources structures. This study was based on the long daily discharge record for the period 1950 - 2008 at station 1EF01 in Kenya, on the Nzoia river with watershed area of 12,676 km² located in the North Eastern quadrant of Lake Victoria Nile Sub Basin. In the statistical modelling of FDCs and T (years, suitable extreme value distributions (EVD were selected and calibrated to fit nearly independent high flows and low flows. The FDCs and T-curves were used to determine the EDT. The FDCs were used to model the QDF relationships. To derive QDF relationships of hydrological extremes, for a given range of aggregation levels, extreme value analysis (EVA was carried out and suitable EVD selected. Next was the calibration of parameters of the EVD and analysis of relationship between the model parameters and aggregation levels. Finally, smooth mathematical relationships were derived using little but acceptable modifications to the model parameters. Such constructed QDF relationships can be used for various applications to estimate cumulative volumes of water available during droughts or floods at various aggregation levels or E (% of hydrological extremes. The EDT when obtained for a range of aggregation levels can also be used to understand

  2. STATISTICAL MODELLING OF FDC AND RETURN PERIODS TO CHARACTERISE QDF AND DESIGN THRESHOLD OF HYDROLOGICAL EXTREMES

    Directory of Open Access Journals (Sweden)

    Charles Onyutha

    2012-12-01

    Full Text Available In this paper, firstly, flow duration curves (FDCs for hydrological extremes were calibrated for a range of aggregation levels and seasons to provide compressed statistical information for water resources management at selected temporal scales and seasons. Secondly, instead of the common approach of using return periods, T (years for deriving discharge duration frequency (QDF relationships, the method of using exceedance frequencies, E (% was introduced so as to provide answer to important question like, what is the streamflow at a given aggregation level and selected E (%?. Thirdly, the concept of estimated design threshold (EDT was introduced and proposed for consideration in the risk analysis for design of water resources structures. This study was based on the long daily discharge record for the period 1950 – 2008 at station 1EF01 in Kenya, on the Nzoia river with watershed area of 12,676 km2 located in the North Eastern quadrant of Lake Victoria Nile Sub Basin. In the statistical modeling of FDCs and T (years, suitable extreme value distributions (EVD were selected and calibrated to fit nearly independent high flows and low flows. The FDCs and T-curves were used to determine the EDT. The FDCs were used to model the QDF relationships. To derive QDF relationships of hydrological extremes, for a given range of aggregation levels, extreme value analysis (EVA was carried out and suitable EVD selected. Next was the calibration of parameters of the EVD and analysis of relationship between the model parameters and aggregation levels. Finally, smooth mathematical relationships were derived using little but acceptable modifications to the model parameters. Such constructed QDF relationships can be used for various applications to estimate cumulative volumes of water available during droughts or floods at various aggregation levels or E (% of hydrological extremes. The EDT when obtained for a range of aggregation levels can also be used to

  3. Evaluating sub-seasonal skill in probabilistic forecasts of Atmospheric Rivers and associated extreme events

    Science.gov (United States)

    Subramanian, A. C.; Lavers, D.; Matsueda, M.; Shukla, S.; Cayan, D. R.; Ralph, M.

    2017-12-01

    Atmospheric rivers (ARs) - elongated plumes of intense moisture transport - are a primary source of hydrological extremes, water resources and impactful weather along the West Coast of North America and Europe. There is strong demand in the water management, societal infrastructure and humanitarian sectors for reliable sub-seasonal forecasts, particularly of extreme events, such as floods and droughts so that actions to mitigate disastrous impacts can be taken with sufficient lead-time. Many recent studies have shown that ARs in the Pacific and the Atlantic are modulated by large-scale modes of climate variability. Leveraging the improved understanding of how these large-scale climate modes modulate the ARs in these two basins, we use the state-of-the-art multi-model forecast systems such as the North American Multi-Model Ensemble (NMME) and the Subseasonal-to-Seasonal (S2S) database to help inform and assess the probabilistic prediction of ARs and related extreme weather events over the North American and European West Coasts. We will present results from evaluating probabilistic forecasts of extreme precipitation and AR activity at the sub-seasonal scale. In particular, results from the comparison of two winters (2015-16 and 2016-17) will be shown, winters which defied canonical El Niño teleconnection patterns over North America and Europe. We further extend this study to analyze probabilistic forecast skill of AR events in these two basins and the variability in forecast skill during certain regimes of large-scale climate modes.

  4. Extreme Quantum Memory Advantage for Rare-Event Sampling

    Science.gov (United States)

    Aghamohammadi, Cina; Loomis, Samuel P.; Mahoney, John R.; Crutchfield, James P.

    2018-02-01

    We introduce a quantum algorithm for memory-efficient biased sampling of rare events generated by classical memoryful stochastic processes. Two efficiency metrics are used to compare quantum and classical resources for rare-event sampling. For a fixed stochastic process, the first is the classical-to-quantum ratio of required memory. We show for two example processes that there exists an infinite number of rare-event classes for which the memory ratio for sampling is larger than r , for any large real number r . Then, for a sequence of processes each labeled by an integer size N , we compare how the classical and quantum required memories scale with N . In this setting, since both memories can diverge as N →∞ , the efficiency metric tracks how fast they diverge. An extreme quantum memory advantage exists when the classical memory diverges in the limit N →∞ , but the quantum memory has a finite bound. We then show that finite-state Markov processes and spin chains exhibit memory advantage for sampling of almost all of their rare-event classes.

  5. Extreme Quantum Memory Advantage for Rare-Event Sampling

    Directory of Open Access Journals (Sweden)

    Cina Aghamohammadi

    2018-02-01

    Full Text Available We introduce a quantum algorithm for memory-efficient biased sampling of rare events generated by classical memoryful stochastic processes. Two efficiency metrics are used to compare quantum and classical resources for rare-event sampling. For a fixed stochastic process, the first is the classical-to-quantum ratio of required memory. We show for two example processes that there exists an infinite number of rare-event classes for which the memory ratio for sampling is larger than r, for any large real number r. Then, for a sequence of processes each labeled by an integer size N, we compare how the classical and quantum required memories scale with N. In this setting, since both memories can diverge as N→∞, the efficiency metric tracks how fast they diverge. An extreme quantum memory advantage exists when the classical memory diverges in the limit N→∞, but the quantum memory has a finite bound. We then show that finite-state Markov processes and spin chains exhibit memory advantage for sampling of almost all of their rare-event classes.

  6. Spatial vulnerability of Australian urban populations to extreme heat events

    Science.gov (United States)

    Loughnan, Margaret; Tapper, Nigel; Phan, Thu; Lynch, Kellie; McInnes, Judith

    2013-04-01

    Extreme heat events pose a risk to the health of all individuals, especially the elderly and the chronically ill, and are associated with an increased demand for healthcare services. In order to address this problem, policy makers' need information about temperatures above which mortality and morbidity of the exposed population is likely to increase, where the vulnerable groups in the community are located, and how the risks from extreme heat events are likely to change in the future. This study identified threshold temperatures for all Australian capital cities, developed a spatial index of population vulnerability, and used climate model output to predict changes in the number of days exceeding temperature thresholds in the future, as well as changes in risk related to changes in urban density and an ageing population. The study has shown that daily maximum and minimum temperatures from the Bureau of Meteorology forecasts can be used to calculate temperature thresholds for heat alert days. The key risk factors related to adverse health outcomes were found to be areas with intense urban heat islands, areas with higher proportions of older people, and areas with ethnic communities. Maps of spatial vulnerability have been developed to provide information to assist emergency managers, healthcare professionals, and ancillary services develop heatwave preparedness plans at a local scale that target vulnerable groups and address heat-related health risks. The numbers of days exceeding current heat thresholds are predicted to increase over the next 20 to 40 years in all Australian capital cities.

  7. Hydrologic effects of natural disruptive events on nuclear repositories

    International Nuclear Information System (INIS)

    Davis, S.N.

    1979-01-01

    This report describes some possible hydrogeologic effects of disruptive events which may affect repositories for nuclear waste. The report concentrates on the effects of natural events which are judged to be most probable

  8. Extreme events as foundation of Levy walks with varying velocity

    International Nuclear Information System (INIS)

    Kutner, Ryszard

    2002-01-01

    In this work we study the role of extreme events [E.W. Montroll, B.J. West, in: J.L. Lebowitz, E.W. Montrell (Eds.), Fluctuation Phenomena, SSM, vol. VII, North-Holland, Amsterdam, 1979, p. 63; J.-P. Bouchaud, M. Potters, Theory of Financial Risks from Statistical Physics to Risk Management, Cambridge University Press, Cambridge, 2001; D. Sornette, Critical Phenomena in Natural Sciences. Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, Springer, Berlin, 2000] in determining the scaling properties of Levy walks with varying velocity. This model is an extension of the well-known Levy walks one [J. Klafter, G. Zumofen, M.F. Shlesinger, in M.F. Shlesinger, G.M. Zaslavsky, U. Frisch (Eds.), Levy Flights and Related Topics ion Physics, Lecture Notes in Physics, vol. 450, Springer, Berlin, 1995, p. 196; G. Zumofen, J. Klafter, M.F. Shlesinger, in: R. Kutner, A. Pekalski, K. Sznajd-Weron (Eds.), Anomalous Diffusion. From Basics to Applications, Lecture Note in Physics, vol. 519, Springer, Berlin, 1999, p. 15] introduced in the context of chaotic dynamics where a fixed value of the walker velocity is assumed for simplicity. Such an extension seems to be necessary when the open and/or complex system is studied. The model of Levy walks with varying velocity is spanned on two coupled velocity-temporal hierarchies: the first one consisting of velocities and the second of corresponding time intervals which the walker spends between the successive turning points. Both these hierarchical structures are characterized by their own self-similar dimensions. The extreme event, which can appear within a given time interval, is defined as a single random step of the walker having largest length. By finding power-laws which describe the time-dependence of this displacement and its statistics we obtained two independent diffusion exponents, which are related to the above-mentioned dimensions and which characterize the extreme event kinetics. In this work we show the

  9. Producing physically consistent and bias free extreme precipitation events over the Switzerland: Bridging gaps between meteorology and impact models

    Science.gov (United States)

    José Gómez-Navarro, Juan; Raible, Christoph C.; Blumer, Sandro; Martius, Olivia; Felder, Guido

    2016-04-01

    Extreme precipitation episodes, although rare, are natural phenomena that can threat human activities, especially in areas densely populated such as Switzerland. Their relevance demands the design of public policies that protect public assets and private property. Therefore, increasing the current understanding of such exceptional situations is required, i.e. the climatic characterisation of their triggering circumstances, severity, frequency, and spatial distribution. Such increased knowledge shall eventually lead us to produce more reliable projections about the behaviour of these events under ongoing climate change. Unfortunately, the study of extreme situations is hampered by the short instrumental record, which precludes a proper characterization of events with return period exceeding few decades. This study proposes a new approach that allows studying storms based on a synthetic, but physically consistent database of weather situations obtained from a long climate simulation. Our starting point is a 500-yr control simulation carried out with the Community Earth System Model (CESM). In a second step, this dataset is dynamically downscaled with the Weather Research and Forecasting model (WRF) to a final resolution of 2 km over the Alpine area. However, downscaling the full CESM simulation at such high resolution is infeasible nowadays. Hence, a number of case studies are previously selected. This selection is carried out examining the precipitation averaged in an area encompassing Switzerland in the ESM. Using a hydrological criterion, precipitation is accumulated in several temporal windows: 1 day, 2 days, 3 days, 5 days and 10 days. The 4 most extreme events in each category and season are selected, leading to a total of 336 days to be simulated. The simulated events are affected by systematic biases that have to be accounted before this data set can be used as input in hydrological models. Thus, quantile mapping is used to remove such biases. For this task

  10. Extreme weather events in Iran under a changing climate

    Science.gov (United States)

    Alizadeh-Choobari, Omid; Najafi, M. S.

    2018-01-01

    Observations unequivocally show that Iran has been rapidly warming over recent decades, which in sequence has triggered a wide range of climatic impacts. Meteorological records of several ground stations across Iran with daily temporal resolution for the period 1951-2013 were analyzed to investigate the climate change and its impact on some weather extremes. Iran has warmed by nearly 1.3 °C during the period 1951-2013 (+0.2 °C per decade), with an increase of the minimum temperature at a rate two times that of the maximum. Consequently, an increase in the frequency of heat extremes and a decrease in the frequency of cold extremes have been observed. The annual precipitation has decreased by 8 mm per decade, causing an expansion of Iran's dry zones. Previous studies have pointed out that warming is generally associated with more frequent heavy precipitation because a warmer air can hold more moisture. Nevertheless, warming in Iran has been associated with more frequent light precipitation, but less frequent moderate, heavy and extremely heavy precipitation. This is because in the subtropical dry zones, a longer time is required to recharge the atmosphere with water vapour in a warmer climate, causing more water vapour to be transported from the subtropics to high latitudes before precipitations forms. In addition, the altitude of the condensation level increases in a warmer climate in subtropical regions, causing an overall decrease of precipitation. We argue that changing in the frequency of heavy precipitation in response to warming varies depending on the geographical location. Warming over the dry subtropical regions is associated with a decrease in the frequency of heavy precipitation, while an increase is expected over both subpolar and tropical regions. The warmer climate has also led to the increase in the frequency of both thunderstorms (driven by convective heating) and dust events over Iran.

  11. Spectral characteristics of the nearshore waves off Paradip, India during monsoon and extreme events

    Digital Repository Service at National Institute of Oceanography (India)

    Aboobacker, V.M.; Vethamony, P.; Sudheesh, K.; Rupali, S.P.

    and directional wave energy spectra distinctly separate out the wave conditions that prevailed off Paradip in the monsoon, fair weather and extreme weather events during the above period. Frequency-energy spectra during extreme events are single peaked...

  12. Assessment of climate change impact on hydrological extremes in two source regions of the Nile River Basin

    Directory of Open Access Journals (Sweden)

    M. T. Taye

    2011-01-01

    Full Text Available The potential impact of climate change was investigated on the hydrological extremes of Nyando River and Lake Tana catchments, which are located in two source regions of the Nile River basin. Climate change scenarios were developed for rainfall and potential evapotranspiration (ETo, considering 17 General Circulation Model (GCM simulations to better understand the range of possible future change. They were constructed by transferring the extracted climate change signals to the observed series using a frequency perturbation downscaling approach, which accounts for the changes in rainfall extremes. Projected changes under two future SRES emission scenarios A1B and B1 for the 2050s were considered. Two conceptual hydrological models were calibrated and used for the impact assessment. Their difference in simulating the flows under future climate scenarios was also investigated.

    The results reveal increasing mean runoff and extreme peak flows for Nyando catchment for the 2050s while unclear trend is observed for Lake Tana catchment for mean volumes and high/low flows. The hydrological models for Lake Tana catchment, however, performed better in simulating the hydrological regimes than for Nyando, which obviously also induces a difference in the reliability of the extreme future projections for both catchments. The unclear impact result for Lake Tana catchment implies that the GCM uncertainty is more important for explaining the unclear trend than the hydrological models uncertainty. Nevertheless, to have a better understanding of future impact, hydrological models need to be verified for their credibility of simulating extreme flows.

  13. Response of snow-dependent hydrologic extremes to continued global warming

    Energy Technology Data Exchange (ETDEWEB)

    Diffenbaugh, Noah [Stanford University; Scherer, Martin [Stanford University; Ashfaq, Moetasim [ORNL

    2012-01-01

    Snow accumulation is critical for water availability in the Northern Hemisphere1,2, raising concern that global warming could have important impacts on natural and human systems in snow-dependent regions1,3. Although regional hydrologic changes have been observed (for example, refs 1,3 5), the time of emergence of extreme changes in snow accumulation and melt remains a key unknown for assessing climate- change impacts3,6,7. We find that the CMIP5 global climate model ensemble exhibits an imminent shift towards low snow years in the Northern Hemisphere, with areas of western North America, northeastern Europe and the Greater Himalaya showing the strongest emergence during the near- termdecadesandat2 Cglobalwarming.Theoccurrenceof extremely low snow years becomes widespread by the late twenty-first century, as do the occurrences of extremely high early-season snowmelt and runoff (implying increasing flood risk), and extremely low late-season snowmelt and runoff (implying increasing water stress). Our results suggest that many snow-dependent regions of the Northern Hemisphere are likely to experience increasing stress from low snow years within the next three decades, and from extreme changes in snow-dominated water resources if global warming exceeds 2 C above the pre-industrial baseline.

  14. Modelling extreme climatic events in Guadalquivir Estuary ( Spain)

    Science.gov (United States)

    Delgado, Juan; Moreno-Navas, Juan; Pulido, Antoine; García-Lafuente, Juan; Calero Quesada, Maria C.; García, Rodrigo

    2017-04-01

    Extreme climatic events, such as heat waves and severe storms are predicted to increase in frequency and magnitude as a consequence of global warming but their socio-ecological effects are poorly understood, particularly in estuarine ecosystems. The Guadalquivir Estuary has been anthropologically modified several times, the original salt marshes have been transformed to grow rice and cotton and approximately one-fourth of the total surface of the estuary is now part of two protected areas, one of them is a UNESCO, MAB Biosphere Reserve. The climatic events are most likely to affect Europe in forthcoming decades and a further understanding how these climatic disturbances drive abrupt changes in the Guadalquivir estuary is needed. A barotropic model has been developed to study how severe storm events affects the estuary by conducting paired control and climate-events simulations. The changes in the local wind and atmospheric pressure conditions in the estuary have been studied in detail and several scenarios are obtained by running the model under control and real storm conditions. The model output has been validated with in situ water elevation and good agreement between modelled and real measurements have been obtained. Our preliminary results show that the model demonstrated the capability describe of the tide-surge levels in the estuary, opening the possibility to study the interaction between climatic events and the port operations and food production activities. The barotropic hydrodynamic model provide spatially explicit information on the key variables governing the tide dynamics of estuarine areas under severe climatic scenarios . The numerical model will be a powerful tool in future climate change mitigation and adaptation programs in a complex socio-ecological system.

  15. 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

  16. Changes in the probability of co-occurring extreme climate events

    Science.gov (United States)

    Diffenbaugh, N. S.

    2017-12-01

    Extreme climate events such as floods, droughts, heatwaves, and severe storms exert acute stresses on natural and human systems. When multiple extreme events co-occur, either in space or time, the impacts can be substantially compounded. A diverse set of human interests - including supply chains, agricultural commodities markets, reinsurance, and deployment of humanitarian aid - have historically relied on the rarity of extreme events to provide a geographic hedge against the compounded impacts of co-occuring extremes. However, changes in the frequency of extreme events in recent decades imply that the probability of co-occuring extremes is also changing, and is likely to continue to change in the future in response to additional global warming. This presentation will review the evidence for historical changes in extreme climate events and the response of extreme events to continued global warming, and will provide some perspective on methods for quantifying changes in the probability of co-occurring extremes in the past and future.

  17. Trends in hydrological extremes in the Senegal and the Niger Rivers

    Science.gov (United States)

    Wilcox, C.; Bodian, A.; Vischel, T.; Panthou, G.; Quantin, G.

    2017-12-01

    In recent years, West Africa has witnessed several floods of unprecedented magnitude. Although the evolution of hydrological extremes has been evaluated in the region to some extent, results lack regional coverage, significance levels, uncertainty estimations, model selection criteria, or a combination of the above. In this study, Generalized Extreme Value (GEV) distributions with and without various non-stationary temporal covariates are applied to annual maxima of daily discharge (AMAX) data sets in the Sudano-Guinean part of the Senegal River basin and in the Sahelian part of the Niger River basin. The data ranges from the 1950s to the 2010s. The two models of best fit most often selected (with an alpha=0.05 certainty level) were 1) a double-linear model for the central tendency parameter (μ) with stationary dispersion (σ) and 2) a double-linear model for both parameters. Change points are relatively consistent for the Senegal basin, with stations switching from a decreasing streamflow trend to an increasing streamflow trend in the early 1980s. In the Niger basin the trend in μ was generally positive with an increase in slope after the change point, but the change point location was less consistent. The study clearly demonstrates the significant trends in extreme discharge values in West Africa over the past six decades. Moreover, it proposes a clear methodology for comparing GEV models and selecting the best for use. The return levels generated from the chosen models can be applied to river basin management and hydraulic works sizing. The results provide a first evaluation of non-stationarity in extreme hydrological values in West Africa that is accompanied by significance levels, uncertainties, and non-stationary return level estimations .

  18. 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

  19. 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).

  20. 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

  1. Extreme flood event reconstruction spanning the last century in the El Bibane Lagoon (southeastern Tunisia: a multi-proxy approach

    Directory of Open Access Journals (Sweden)

    A. Affouri

    2017-06-01

    Full Text Available Climate models project that rising atmospheric carbon dioxide concentrations will increase the frequency and the severity of some extreme weather events. The flood events represent a major risk for populations and infrastructures settled on coastal lowlands. Recent studies of lagoon sediments have enhanced our knowledge on extreme hydrological events such as palaeo-storms and on their relation with climate change over the last millennium. However, few studies have been undertaken to reconstruct past flood events from lagoon sediments. Here, the past flood activity was investigated using a multi-proxy approach combining sedimentological and geochemical analysis of surfaces sediments from a southeastern Tunisian catchment in order to trace the origin of sediment deposits in the El Bibane Lagoon. Three sediment sources were identified: marine, fluvial and aeolian. When applying this multi-proxy approach on core BL12-10, recovered from the El Bibane Lagoon, we can see that finer material, a high content of the clay and silt, and a high content of the elemental ratios (Fe ∕ Ca and Ti ∕ Ca characterise the sedimentological signature of the palaeo-flood levels identified in the lagoonal sequence. For the last century, which is the period covered by the BL12-10 short core, three palaeo-flood events were identified. The age of these flood events have been determined by 210Pb and 137Cs chronology and give ages of AD 1995 ± 6, 1970 ± 9 and 1945 ± 9. These results show a good temporal correlation with historical flood events recorded in southern Tunisia in the last century (AD 1932, 1969, 1979 and 1995. Our finding suggests that reconstruction of the history of the hydrological extreme events during the upper Holocene is possible in this location through the use of the sedimentary archives.

  2. 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

  3. Estimation of initiating event frequency for external flood events by extreme value theorem

    International Nuclear Information System (INIS)

    Chowdhury, Sourajyoti; Ganguly, Rimpi; Hari, Vibha

    2017-01-01

    External flood is an important common cause initiating event in nuclear power plants (NPPs). It may potentially lead to severe core damage (SCD) by first causing the failure of the systems required for maintaining the heat sinks and then by contributing to failures of engineered systems designed to mitigate such failures. The sample NPP taken here is twin 220 MWe Indian standard pressurized heavy water reactor (PHWR) situated inland. A comprehensive in-house Level-1 internal event PSA for full power had already been performed. External flood assessment was further conducted in area of external hazard risk assessment in response to post-Fukushima measures taken in nuclear industries. The present paper describes the methodology to calculate initiating event (IE) frequency for external flood events for the sample inland Indian NPP. General extreme value (GEV) theory based on maximum likelihood method (MLM) and order statistics approach (OSA) is used to analyse the rainfall data for the site. Thousand-year return level and necessary return periods for extreme rainfall are evaluated. These results along with plant-specific topographical calculations quantitatively establish that external flooding resulting from upstream dam break, river flooding and heavy rainfall (flash flood) would be unlikely for the sample NPP in consideration.

  4. Intensity changes in future extreme precipitation: A statistical event-based approach.

    Science.gov (United States)

    Manola, Iris; van den Hurk, Bart; de Moel, Hans; Aerts, Jeroen

    2017-04-01

    Short-lived precipitation extremes are often responsible for hazards in urban and rural environments with economic and environmental consequences. The precipitation intensity is expected to increase about 7% per degree of warming, according to the Clausius-Clapeyron (CC) relation. However, the observations often show a much stronger increase in the sub-daily values. In particular, the behavior of the hourly summer precipitation from radar observations with the dew point temperature (the Pi-Td relation) for the Netherlands suggests that for moderate to warm days the intensification of the precipitation can be even higher than 21% per degree of warming, that is 3 times higher than the expected CC relation. The rate of change depends on the initial precipitation intensity, as low percentiles increase with a rate below CC, the medium percentiles with 2CC and the moderate-high and high percentiles with 3CC. This non-linear statistical Pi-Td relation is suggested to be used as a delta-transformation to project how a historic extreme precipitation event would intensify under future, warmer conditions. Here, the Pi-Td relation is applied over a selected historic extreme precipitation event to 'up-scale' its intensity to warmer conditions. Additionally, the selected historic event is simulated in the high-resolution, convective-permitting weather model Harmonie. The initial and boundary conditions are alternated to represent future conditions. The comparison between the statistical and the numerical method of projecting the historic event to future conditions showed comparable intensity changes, which depending on the initial percentile intensity, range from below CC to a 3CC rate of change per degree of warming. The model tends to overestimate the future intensities for the low- and the very high percentiles and the clouds are somewhat displaced, due to small wind and convection changes. The total spatial cloud coverage in the model remains, as also in the statistical

  5. Uncertainty in projected point precipitation extremes for hydrological impact analysis of climate change

    Science.gov (United States)

    Van Uytven, Els; Willems, Patrick

    2017-04-01

    Current trends in the hydro-meteorological variables indicate the potential impact of climate change on hydrological extremes. Therefore, they trigger an increased importance climate adaptation strategies in water management. The impact of climate change on hydro-meteorological and hydrological extremes is, however, highly uncertain. This is due to uncertainties introduced by the climate models, the internal variability inherent to the climate system, the greenhouse gas scenarios and the statistical downscaling methods. In view of the need to define sustainable climate adaptation strategies, there is a need to assess these uncertainties. This is commonly done by means of ensemble approaches. Because more and more climate models and statistical downscaling methods become available, there is a need to facilitate the climate impact and uncertainty analysis. A Climate Perturbation Tool has been developed for that purpose, which combines a set of statistical downscaling methods including weather typing, weather generator, transfer function and advanced perturbation based approaches. By use of an interactive interface, climate impact modelers can apply these statistical downscaling methods in a semi-automatic way to an ensemble of climate model runs. The tool is applicable to any region, but has been demonstrated so far to cases in Belgium, Suriname, Vietnam and Bangladesh. Time series representing future local-scale precipitation, temperature and potential evapotranspiration (PET) conditions were obtained, starting from time series of historical observations. Uncertainties on the future meteorological conditions are represented in two different ways: through an ensemble of time series, and a reduced set of synthetic scenarios. The both aim to span the full uncertainty range as assessed from the ensemble of climate model runs and downscaling methods. For Belgium, for instance, use was made of 100-year time series of 10-minutes precipitation observations and daily

  6. Changes in Extreme Events and the Potential Impacts on National Security

    Science.gov (United States)

    Bell, J.

    2017-12-01

    Extreme weather and climate events affect human health by causing death, injury, and illness, as well as having large socio-economic impacts. Climate change has caused changes in extreme event frequency, intensity and geographic distribution, and will continue to be a driver for changes in the future. Some of the extreme events that have already changed are heat waves, droughts, wildfires, flooding rains, coastal flooding, storm surge, and hurricanes. The pathways connecting extreme events to health outcomes and economic losses can be diverse and complex. The difficulty in predicting these relationships comes from the local intricacies of societal and environmental factors that influences the level of exposure. The goal of this presentation is to discuss the national security implications of changes in extreme weather events and demonstrate how changes in extremes can lead to a host cascading issues. To illustrate this point, this presentation will provide examples of the various pathways that extreme events can increase disease burden and cause economic stress.

  7. Transient phenomena in cosmic ray intensity during extreme events

    Science.gov (United States)

    Agarwal, Rekha; Mishra, Rajesh K.

    2008-04-01

    In the present work an analysis has been made of the extreme events occurring during July 2005. Specifically, a rather intense Forbush decrease was observed at different neutron monitors all over the world during 16 July 2005. An effort has been made to study the effect of this unusual event on cosmic ray intensity as well as various solar and interplanetary plasma parameters. It is noteworthy that during 11 to 18 July 2005 the solar activity ranged from low to very active. Especially low levels occurred on 11, 15, and 17 July whereas high levels took place on 14 and 16 July 2005. The Sun is observed to be active during 11 to 18 July 2005, the interplanetary magnetic field intensity lies within 15 nT, and solar wind velocity was limited to ˜500 kms-1. The geomagnetic activity during this period remains very quiet, the Kp index did not exceed 5, the disturbance storm time Dst index remains ˜-70 nT and no sudden storm commencement has been detected during this period. It is noted that for the majority of the hours, the north/south component of the interplanetary magnetic field, Bz, remains negative, and the cosmic ray intensity increases and shows good/high correlation with Bz, as the polarity of Bz tends to shift from negative to positive values, the intensity decreases and shows good/high anti-correlation with Bz. The cosmic ray intensity tends to decrease with increase of interplanetary magnetic field strength (B) and shows anti-correlation for the majority of the days.

  8. Evaluation of extreme temperature events in northern Spain based on process control charts

    Science.gov (United States)

    Villeta, M.; Valencia, J. L.; Saá, A.; Tarquis, A. M.

    2018-02-01

    Extreme climate events have recently attracted the attention of a growing number of researchers because these events impose a large cost on agriculture and associated insurance planning. This study focuses on extreme temperature events and proposes a new method for their evaluation based on statistical process control tools, which are unusual in climate studies. A series of minimum and maximum daily temperatures for 12 geographical areas of a Spanish region between 1931 and 2009 were evaluated by applying statistical process control charts to statistically test whether evidence existed for an increase or a decrease of extreme temperature events. Specification limits were determined for each geographical area and used to define four types of extreme anomalies: lower and upper extremes for the minimum and maximum anomalies. A new binomial Markov extended process that considers the autocorrelation between extreme temperature events was generated for each geographical area and extreme anomaly type to establish the attribute control charts for the annual fraction of extreme days and to monitor the occurrence of annual extreme days. This method was used to assess the significance of changes and trends of extreme temperature events in the analysed region. The results demonstrate the effectiveness of an attribute control chart for evaluating extreme temperature events. For example, the evaluation of extreme maximum temperature events using the proposed statistical process control charts was consistent with the evidence of an increase in maximum temperatures during the last decades of the last century.

  9. 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

  10. 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

  11. Understanding the Impacts of Climate and Hydrologic Extremes on Diarrheal Diseases in Southwestern Amazon

    Science.gov (United States)

    Fonseca, P. A. M.

    2015-12-01

    Bacterial diarrheal diseases have a high incidence rate during and after flooding episodes. In the Brazilian Amazon, flood extreme events have become more frequent, leading to high incidence rates for infant diarrhea. In this study we aimed to find a statistical association between rainfall, river levels and diarrheal diseases in children under 5, in the river Acre basin, in the State of Acre (Brazil). We also aimed to identify the time-lag and annual season of extreme rainfall and flooding in different cities in the water basin. The results using Tropical Rainfall Measuring Mission (TRMM) Satellite rainfall data show robustness of these estimates against observational stations on-ground. The Pearson coefficient correlation results (highest 0.35) indicate a time-lag, up to 4 days in three of the cities in the water-basin. In addition, a correlation was also tested between monthly accumulated rainfall and the diarrheal incidence during the rainy season (DJF). Correlation results were higher, especially in Acrelândia (0.7) and Brasiléia and Epitaciolândia (0.5). The correlation between water level monthly averages and diarrheal diseases incidence was 0.3 and 0.5 in Brasiléia and Epitaciolândia. The time-lag evidence found in this paper is critical to inform stakeholders, local populations and civil defense authorities about the time available for preventive and adaptation measures between extreme rainfall and flooding events in vulnerable cities. This study was part of a pilot application in the state of Acre of the PULSE-Brazil project (http://www.pulse-brasil.org/tool/), an interface of climate, environmental and health data to support climate adaptation. The next step of this research is to expand the analysis to other climate variables on diarrheal diseases across the whole Brazilian Amazon Basin and estimate the relative risk (RR) of a child getting sick. A statistical model will estimate RR based on the observed values and seasonal forecasts (higher

  12. 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

  13. Possible Future Climate Change Impacts on the Hydrological Drought Events in the Weihe River Basin, China

    Directory of Open Access Journals (Sweden)

    Fei Yuan

    2016-01-01

    Full Text Available Quantitative evaluation of future climate change impacts on hydrological drought characteristics is one of important measures for implementing sustainable water resources management and effective disaster mitigation in drought-prone regions under the changing environment. In this study, a modeling system for projecting the potential future climate change impacts on hydrological droughts in the Weihe River basin (WRB in North China is presented. This system consists of a large-scale hydrological model driven by climate outputs from three climate models (CMs for future streamflow projections, a probabilistic model for univariate drought assessment, and a copula-based bivariate model for joint drought frequency analysis under historical and future climates. With the observed historical climate data as the inputs, the Variable Infiltration Capacity hydrological model projects an overall runoff reduction in the WRB under the Intergovernmental Panel on Climate Change A1B scenario. The univariate drought assessment found that although fewer hydrological drought events would occur under A1B scenario, drought duration and severity tend to increase remarkably. Moreover, the bivariate drought assessment reveals that future droughts in the same return period as the baseline droughts would become more serious. With these trends in the future, the hydrological drought situation in the WRB would be further deteriorated.

  14. Enhanced hydrological extremes in the western United States under global warming through the lens of water vapor wave activity

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jian; Xue, Daokai; Gao, Yang; Chen, Gang; Leung, Lai-Yung; Staten, Paul W.

    2018-04-23

    Understanding how regional hydrological extremes would respond to warming is a grand challenge to the community of climate change research. To address this challenge, we construct an analysis framework based on column integrated water vapor (CWV) wave activity to diagnose the wave component of the hydrological cycle that contributes to hydrological extremes. By applying the analysis to the historical and future climate projections from the CMIP5 models, we found that the wet-versus-dry disparity of daily net precipitation along a zonal band can increase at a super Clausius-Clapeyron rate due to the enhanced stirring length of wave activity at the poleward flank of the mean storm track. The local variant of CWV wave activity reveals the unique characteristics of atmospheric rivers (ARs) in terms of their transport function, enhanced mixing and hydrological cycling rate (HC). Under RCP8.5, the local moist wave activity increases by ~40% over the northeastern Pacific by the end of the 21st century, indicating more ARs hitting the west coast, giving rise to a ~20% increase in the related hydrological extremes − $ despite a weakening of the local HC.

  15. Detecting and taking into account possible impacts of climate change on hydrological extremes

    International Nuclear Information System (INIS)

    Renard, B.

    2008-01-01

    Climate change is widely considered as a reality by scientists. Nevertheless, impacts on hydrological extremes are more difficult to observe and to forecast. The aim of this thesis is to answer the following questions: How to detect changes in hydro-climatic series? What are the observed changes for extreme discharges in France? How to take into account possible changes in frequency analysis? These objectives refer to both local and regional scales. This paper describes the developments related to the third question. In a first step, the concept of return period is revisited in a non-stationary context. Frequency analysis methods are then updated in order to account for evolutions in time. This is achieved by modelling trends affecting the distribution parameters. Parameter estimation uses the Bayesian formalism, which is a convenient tool for quantifying the uncertainty related to the stationarity hypothesis. This approach can be generalized at the regional scale, by means of non-stationary regional models. Such models are more general than the model underlying the index flood method. However, results of such a regional analysis are affected by the spatial dependence existing between studied sites. Impacts of this dependence on quantile estimates are highlighted, and a first approach is proposed in order to explicitly model spatial dependence. (author)

  16. A hydro-meteorological model chain to assess the influence of natural variability and impacts of climate change on extreme events and propose optimal water management

    Science.gov (United States)

    von Trentini, F.; Willkofer, F.; Wood, R. R.; Schmid, F. J.; Ludwig, R.

    2017-12-01

    The ClimEx project (Climate change and hydrological extreme events - risks and perspectives for water management in Bavaria and Québec) focuses on the effects of climate change on hydro-meteorological extreme events and their implications for water management in Bavaria and Québec. Therefore, a hydro-meteorological model chain is applied. It employs high performance computing capacity of the Leibniz Supercomputing Centre facility SuperMUC to dynamically downscale 50 members of the Global Circulation Model CanESM2 over European and Eastern North American domains using the Canadian Regional Climate Model (RCM) CRCM5. Over Europe, the unique single model ensemble is conjointly analyzed with the latest information provided through the CORDEX-initiative, to better assess the influence of natural climate variability and climatic change in the dynamics of extreme events. Furthermore, these 50 members of a single RCM will enhance extreme value statistics (extreme return periods) by exploiting the available 1500 model years for the reference period from 1981 to 2010. Hence, the RCM output is applied to drive the process based, fully distributed, and deterministic hydrological model WaSiM in high temporal (3h) and spatial (500m) resolution. WaSiM and the large ensemble are further used to derive a variety of hydro-meteorological patterns leading to severe flood events. A tool for virtual perfect prediction shall provide a combination of optimal lead time and management strategy to mitigate certain flood events following these patterns.

  17. Vulnerability of solar energy infrastructure and output to extreme events: Climate change implications (Conference paper)

    OpenAIRE

    Patt, A.; Pfenninger, S.; Lilliestam, J.

    2010-01-01

    This paper explores the potential vulnerability of solar energy systems to future extreme event risks as a consequence of climate change. We describe the three main technologies likely to be used to harness sunlight -- thermal heating, photovoltaic (PV), and concentrating solar power (CSP) -- and identify critical extreme event vulnerabilities for each one. We then compare these vulnerabilities with assessments of future changes in extreme event risk levels. We do not identify any vulnerabili...

  18. 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

  19. Estimating the impact of extreme events on crude oil price. An EMD-based event analysis method

    International Nuclear Information System (INIS)

    Zhang, Xun; Wang, Shouyang; Yu, Lean; Lai, Kin Keung

    2009-01-01

    The impact of extreme events on crude oil markets is of great importance in crude oil price analysis due to the fact that those events generally exert strong impact on crude oil markets. For better estimation of the impact of events on crude oil price volatility, this study attempts to use an EMD-based event analysis approach for this task. In the proposed method, the time series to be analyzed is first decomposed into several intrinsic modes with different time scales from fine-to-coarse and an average trend. The decomposed modes respectively capture the fluctuations caused by the extreme event or other factors during the analyzed period. It is found that the total impact of an extreme event is included in only one or several dominant modes, but the secondary modes provide valuable information on subsequent factors. For overlapping events with influences lasting for different periods, their impacts are separated and located in different modes. For illustration and verification purposes, two extreme events, the Persian Gulf War in 1991 and the Iraq War in 2003, are analyzed step by step. The empirical results reveal that the EMD-based event analysis method provides a feasible solution to estimating the impact of extreme events on crude oil prices variation. (author)

  20. Estimating the impact of extreme events on crude oil price. An EMD-based event analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xun; Wang, Shouyang [Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); School of Mathematical Sciences, Graduate University of Chinese Academy of Sciences, Beijing 100190 (China); Yu, Lean [Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Lai, Kin Keung [Department of Management Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon (China)

    2009-09-15

    The impact of extreme events on crude oil markets is of great importance in crude oil price analysis due to the fact that those events generally exert strong impact on crude oil markets. For better estimation of the impact of events on crude oil price volatility, this study attempts to use an EMD-based event analysis approach for this task. In the proposed method, the time series to be analyzed is first decomposed into several intrinsic modes with different time scales from fine-to-coarse and an average trend. The decomposed modes respectively capture the fluctuations caused by the extreme event or other factors during the analyzed period. It is found that the total impact of an extreme event is included in only one or several dominant modes, but the secondary modes provide valuable information on subsequent factors. For overlapping events with influences lasting for different periods, their impacts are separated and located in different modes. For illustration and verification purposes, two extreme events, the Persian Gulf War in 1991 and the Iraq War in 2003, are analyzed step by step. The empirical results reveal that the EMD-based event analysis method provides a feasible solution to estimating the impact of extreme events on crude oil prices variation. (author)

  1. Hydrology

    Science.gov (United States)

    Sharp, John M.

    1977-01-01

    Lists many recent research projects in hydrology, including flow in fractured media, improvements in remote-sensing techniques, effects of urbanization on water resources, and developments in drainage basins. (MLH)

  2. Hydrology

    International Nuclear Information System (INIS)

    Obando G, E.

    1989-01-01

    Isotopical techniques are used in hydrology area for exploration, evaluation and exploration of water investigation. These techniques have been used successfully and are often the best or only means for providing certain hydrogeological parameters

  3. Modelling of spatio-temporal precipitation relevant for urban hydrology with focus on scales, extremes and climate change

    DEFF Research Database (Denmark)

    Sørup, Hjalte Jomo Danielsen

    -correlation lengths for sub-daily extreme precipitation besides having too low intensities. Especially the wrong spatial correlation structure is disturbing from an urban hydrological point of view as short-term extremes will cover too much ground if derived directly from bias corrected regional climate model output...... of precipitation are compared and used to rank climate models with respect to performance metrics. The four different observational data sets themselves are compared at daily temporal scale with respect to climate indices for mean and extreme precipitation. Data density seems to be a crucial parameter for good...... happening in summer and most of the daily extremes in fall. This behaviour is in good accordance with reality where short term extremes originate in convective precipitation cells that occur when it is very warm and longer term extremes originate in frontal systems that dominate the fall and winter seasons...

  4. Climate change impacts on extreme events in the United States: an uncertainty analysis

    Science.gov (United States)

    Extreme weather and climate events, such as heat waves, droughts and severe precipitation events, have substantial impacts on ecosystems and the economy. However, future climate simulations display large uncertainty in mean changes. As a result, the uncertainty in future changes ...

  5. Extreme heat event projections for a coastal megacity

    Science.gov (United States)

    Ortiz, L. E.; Gonzalez, J.

    2017-12-01

    As summers become warmer, extreme heat events are expected to increase in intensity, frequency, and duration. Large urban centers may affect these projections by introducing feedbacks between the atmosphere and the built environment through processes involving anthropogenic heat, wind modification, radiation blocking, and others. General circulation models are often run with spatial resolutions in the order of 100 km, limiting their skill at resolving local scale processes and highly spatially varying features such as cities' heterogeneous landscape and mountain topography. This study employs climate simulations using the Weather Research and Forecast (WRF) model coupled with a modified multi-layer urban canopy and building energy model to downscale CESM1 at 1 km horizontal resolution across three time slices (2006-2010, 2075-2079, and 2095-2099) and two projections (RCP 4.5 and 8.5). New York City Metropolitan area, with a population of over 20 million and a complex urban canopy, is used as a case study. The urban canopy model of WRF was modified to include a drag coefficient as a function of the building plant area fraction and the introduction of evaporative cooling systems at building roofs to reject the anthropogenic heat from the buildings, with urban canopy parameters computed from the New York City Property Land-Use Tax-lot Output (PLUTO). Model performance is evaluated against the input model and historical records from airport stations, showing improvement in the statistical characteristics in the downscaled model output. Projection results are presented as spatially distributed anomalies in heat wave frequency, duration, and maximum intensity from the 2006-2010 benchmark period. Results show that local sea-breeze circulations mitigate heat wave impacts, following a positive gradient with increasing distance from the coastline. However, end of century RCP 8.5 projections show the possibility of reversal of this pattern, sea surface temperatures increase

  6. The study of the hydrological regime extreme effects of the Caspian Sea during the XX-XXI centuries

    Science.gov (United States)

    Yaitskaya, Natalia

    2016-04-01

    The Caspian Sea - the unique largest enclosed inland body of water on Earth. Significant periodic sea level fluctuations are a typical feature of the sea. In the XIX-XX centuries a number of comprehensive studies of the Caspian Sea was carried out. The results are published in the papers, monographs and climatic atlases. But a number of fundamental questions about the features of the hydrological regime of the Caspian Sea is still open: 1. How does the water circulation change during the level variations? 2. What is the effect of heterogeneity of evaporation from the water surface on the formation of the flow field in the conditions of long-term level changes? 3. How does the water salinity regime change depending on the sea level position, water circulation, river flow and different climatic influences? 4. What is the effect of extreme events (multi-hazards) (ice, storms, destruction of the coasts) on coastal infrastructure? In 2016, the project aims to study hydrological regime extreme effects of the Caspian Sea was supported by the Russian Foundation for Basic Research. Within this project all of the above problems will be solved. Geographic information system "Caspian Sea" for the storage and data processing, including a database of primary oceanographic information for the period of instrumental observations (1897-2013), cartographic database (1921-2011) and tools for multidimensional analysis of spatio-temporal information is the basis of the study. The scheme of interconnected hydrodynamic models (Caspian Sea MODel - Ocean Model - Wind wave model) was developed. The important factors are taken into account in the structure of the models: long-term and seasonal dynamics of the sea waves parameters, new long-term values of evaporation from the shallow waters areas of the Caspian Sea, water circulation. Schemes of general seasonal circulation of the Caspian Sea and the Northern Caspian at different positions of the sea level in XX-XXI centuries using

  7. Impact of Climate Change on Hydrologic Extremes in the Upper Basin of the Yellow River Basin of China

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2016-01-01

    Full Text Available To reveal the revolution law of hydrologic extremes in the next 50 years and analyze the impact of climate change on hydrologic extremes, the following main works were carried on: firstly, the long duration (15 d, 30 d, and 60 d rainfall extremes according to observed time-series and forecast time-series by dynamical climate model product (BCC-CSM-1.1 were deduced, respectively, on the basis that the quantitative estimation of the impact of climate change on rainfall extremes was conducted; secondly, the SWAT model was used to deduce design flood with the input of design rainfall for the next 50 years. On this basis, quantitative estimation of the impact of climate change on long duration flood volume extremes was conducted. It indicates that (1 the value of long duration rainfall extremes for given probabilities (1%, 2%, 5%, and 10% of the Tangnaihai basin will rise with slight increasing rate from 1% to 6% in the next 50 years and (2 long duration flood volume extremes of given probabilities of the Tangnaihai basin will rise with slight increasing rate from 1% to 6% in the next 50 years. The conclusions may provide technical supports for basin level planning of flood control and hydropower production.

  8. Hydrology

    Science.gov (United States)

    Brutsaert, Wilfried

    2005-08-01

    Water in its different forms has always been a source of wonder, curiosity and practical concern for humans everywhere. Hydrology - An Introduction presents a coherent introduction to the fundamental principles of hydrology, based on the course that Wilfried Brutsaert has taught at Cornell University for the last thirty years. Hydrologic phenomena are dealt with at spatial and temporal scales at which they occur in nature. The physics and mathematics necessary to describe these phenomena are introduced and developed, and readers will require a working knowledge of calculus and basic fluid mechanics. The book will be invaluable as a textbook for entry-level courses in hydrology directed at advanced seniors and graduate students in physical science and engineering. In addition, the book will be more broadly of interest to professional scientists and engineers in hydrology, environmental science, meteorology, agronomy, geology, climatology, oceanology, glaciology and other earth sciences. Emphasis on fundamentals Clarification of the underlying physical processes Applications of fluid mechanics in the natural environment

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

    International Nuclear Information System (INIS)

    Jentsch, A.; Jentsch, A.; Beierkuhnlein, C.

    2008-01-01

    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)

  10. Impact of climate change on extreme rainfall events and flood risk

    Indian Academy of Sciences (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 ...

  11. 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.

  12. Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events

    OpenAIRE

    Axelsson, Charles; van Sebille, Erik

    2017-01-01

    The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic leakage is extremely pertinent. Here, we explore why and how coastal cities can reduce macroplastic leakages during extreme rainfall events. Using nine global cities as a basis, we establish that while c...

  13. Coupling atmospheric, hydrological and hydraulic models to develop a catalogue of worst-case scenarios for extreme flooding in Switzerland

    Science.gov (United States)

    José Gómez-Navarro, Juan; Felder, Guido; Raible, Christoph C.; Martius, Olivia; Rössler, Ole

    2015-04-01

    the high-resolution simulation (as it is driven by the boundary conditions provided by the GCM), the spatial structure of the precipitation is refined, producing stronger precipitation gradients that allow to identify the main orographic barriers. Further on, much higher precipitation rates occur in some river catchments, which are indicative of potential disastrous situations at very localised regions. In a next step, the results of the atmospheric-alone RCM simulations will be used to drive the hydrological model PREVAH. This model produces event hydrographs, that represent plausible catchment reactions on the simulated precipitation produced by the RCM. The event hydrographs will be then routed with the 1D/2D hydraulic model BASEMENT-ETH, that accounts for the retention effects of lakes and inundated areas. Hence, the described model chain will eventually simulate a number of physically plausible peak discharges in Switzerland that are determined by the most extreme situations occurring in the GCM simulation. This will enable the analysis and characterisation of worst-case floodings in Switzerland whose return period exceeds several centuries.

  14. Predicting the extreme 2015/16 El Nino event

    CSIR Research Space (South Africa)

    Mpheshea, LE

    2015-09-01

    Full Text Available A strong El Niño phenomenon is expected to develop during the austral summer. This study seeks to address the two main questions. 1) How strong will the 2016 event be? 2) With how much skill and confidence can a really strong event be predicted? A...

  15. Ultimate design load analysis of planetary gearbox bearings under extreme events

    DEFF Research Database (Denmark)

    Gallego Calderon, Juan Felipe; Natarajan, Anand; Cutululis, Nicolaos Antonio

    2017-01-01

    This paper investigates the impact of extreme events on the planet bearings of a 5 MW gearbox. The system is simulated using an aeroelastic tool, where the turbine structure is modeled, and MATLAB/Simulink, where the drivetrain (gearbox and generator) are modeled using a lumped-parameter approach....... Three extreme events are assessed: low-voltage ride through, emergency stop and normal stop. The analysis is focused on finding which event has the most negative impact on the bearing extreme radial loads. The two latter events are carried out following the guidelines of the International...

  16. Directional Considerations for Extreme Wind Climatic Events in the ...

    African Journals Online (AJOL)

    This paper takes a look at the importance and role of probability concepts structural design of transmission line. The reliability of transmission structure is clearly a function of the maximum loads that may be imposed over the useful life of the structure. These loads are, more often than not, caused by the extreme atmospheric ...

  17. Detecting impacts of extreme events with ecological in situ monitoring networks

    Directory of Open Access Journals (Sweden)

    M. D. Mahecha

    2017-09-01

    Full Text Available Extreme hydrometeorological conditions typically impact ecophysiological processes on land. Satellite-based observations of the terrestrial biosphere provide an important reference for detecting and describing the spatiotemporal development of such events. However, in-depth investigations of ecological processes during extreme events require additional in situ observations. The question is whether the density of existing ecological in situ networks is sufficient for analysing the impact of extreme events, and what are expected event detection rates of ecological in situ networks of a given size. To assess these issues, we build a baseline of extreme reductions in the fraction of absorbed photosynthetically active radiation (FAPAR, identified by a new event detection method tailored to identify extremes of regional relevance. We then investigate the event detection success rates of hypothetical networks of varying sizes. Our results show that large extremes can be reliably detected with relatively small networks, but also reveal a linear decay of detection probabilities towards smaller extreme events in log–log space. For instance, networks with  ≈  100 randomly placed sites in Europe yield a  ≥  90 % chance of detecting the eight largest (typically very large extreme events; but only a  ≥  50 % chance of capturing the 39 largest events. These findings are consistent with probability-theoretic considerations, but the slopes of the decay rates deviate due to temporal autocorrelation and the exact implementation of the extreme event detection algorithm. Using the examples of AmeriFlux and NEON, we then investigate to what degree ecological in situ networks can capture extreme events of a given size. Consistent with our theoretical considerations, we find that today's systematically designed networks (i.e. NEON reliably detect the largest extremes, but that the extreme event detection rates are not higher than would

  18. Hydrologi

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    Hydro1ogi er den videnskab, der omhand1er jordens vand, dets forekomst, cirku1ation og forde1ing, dets kemiske og fysiske egenskaber samt indvirkning på omgivelserne, herunder dets relation ti1 alt liv på jorden. Således lyder en b1andt mange definitioner på begrebet hydrologi, og som man kan se...

  19. Assessing uncertainty in extreme events: Applications to risk-based decision making in interdependent infrastructure sectors

    International Nuclear Information System (INIS)

    Barker, Kash; Haimes, Yacov Y.

    2009-01-01

    Risk-based decision making often relies upon expert probability assessments, particularly in the consequences of disruptive events and when such events are extreme or catastrophic in nature. Naturally, such expert-elicited probability distributions can be fraught with errors, as they describe events which occur very infrequently and for which only sparse data exist. This paper presents a quantitative framework, the extreme event uncertainty sensitivity impact method (EE-USIM), for measuring the sensitivity of extreme event consequences to uncertainties in the parameters of the underlying probability distribution. The EE-USIM is demonstrated with the Inoperability input-output model (IIM), a model with which to evaluate the propagation of inoperability throughout an interdependent set of economic and infrastructure sectors. The EE-USIM also makes use of a two-sided power distribution function generated by expert elicitation of extreme event consequences

  20. A hydrological analysis of the 4 November 2011 event in Genoa

    Directory of Open Access Journals (Sweden)

    F. Silvestro

    2012-09-01

    Full Text Available On the 4 November 2011 a flash flood event hit the area of Genoa with dramatic consequences. Such an event represents, from the meteorological and hydrological perspective, a paradigm of flash floods in the Mediterranean environment.

    The hydro-meteorological probabilistic forecasting system for small and medium size catchments in use at the Civil Protection Centre of Liguria region exhibited excellent performances for the event, by predicting, 24–48 h in advance, the potential level of risk associated with the forecast. It greatly helped the decision makers in issuing a timely and correct alert.

    In this work we present the operational outputs of the system provided during the Liguria events and the post event hydrological modelling analysis that has been carried out accounting also for the crowd sourcing information and data. We discuss the benefit of the implemented probabilistic systems for decision-making under uncertainty, highlighting how, in this case, the multi-catchment approach used for predicting floods in small basins has been crucial.

  1. Analyzing phenological extreme events over the past five decades in Germany

    Science.gov (United States)

    Schleip, Christoph; Menzel, Annette; Estrella, Nicole; Graeser, Philipp

    2010-05-01

    As climate change may alter the frequency and intensity of extreme temperatures, we analysed whether warming of the last 5 decades has already changed the statistics of phenological extreme events. In this context, two extreme value statistical concepts are discussed and applied to existing phenological datasets of German Weather Service (DWD) in order to derive probabilities of occurrence for extreme early or late phenological events. We analyse four phenological groups; "begin of flowering, "leaf foliation", "fruit ripening" and "leaf colouring" as well as DWD indicator phases of the "phenological year". Additionally we put an emphasis on a between-species analysis; a comparison of differences in extreme onsets between three common northern conifers. Furthermore we conducted a within-species analysis with different phases of horse chestnut throughout a year. The first statistical approach fits data to a Gaussian model using traditional statistical techniques, and then analyses the extreme quantile. The key point of this approach is the adoption of an appropriate probability density function (PDF) to the observed data and the assessment of the PDF parameters change in time. The full analytical description in terms of the estimated PDF for defined time steps of the observation period allows probability assessments of extreme values for e.g. annual or decadal time steps. Related with this approach is the possibility of counting out the onsets which fall in our defined extreme percentiles. The estimation of the probability of extreme events on the basis of the whole data set is in contrast to analyses with the generalized extreme value distribution (GEV). The second approach deals with the extreme PDFs itself and fits the GEV distribution to annual minima of phenological series to provide useful estimates about return levels. For flowering and leaf unfolding phases exceptionally early extremes are seen since the mid 1980s and especially for the single years 1961

  2. The use of distributed hydrological models for the Gard 2002 flash flood event: Analysis of associated hydrological processes

    Science.gov (United States)

    Braud, Isabelle; Roux, Hélène; Anquetin, Sandrine; Maubourguet, Marie-Madeleine; Manus, Claire; Viallet, Pierre; Dartus, Denis

    2010-11-01

    SummaryThis paper presents a detailed analysis of the September 8-9, 2002 flash flood event in the Gard region (southern France) using two distributed hydrological models: CVN built within the LIQUID® hydrological platform and MARINE. The models differ in terms of spatial discretization, infiltration and water redistribution representation, and river flow transfer. MARINE can also account for subsurface lateral flow. Both models are set up using the same available information, namely a DEM and a pedology map. They are forced with high resolution radar rainfall data over a set of 18 sub-catchments ranging from 2.5 to 99 km2 and are run without calibration. To begin with, models simulations are assessed against post field estimates of the time of peak and the maximum peak discharge showing a fair agreement for both models. The results are then discussed in terms of flow dynamics, runoff coefficients and soil saturation dynamics. The contribution of the subsurface lateral flow is also quantified using the MARINE model. This analysis highlights that rainfall remains the first controlling factor of flash flood dynamics. High rainfall peak intensities are very influential of the maximum peak discharge for both models, but especially for the CVN model which has a simplified overland flow transfer. The river bed roughness also influences the peak intensity and time. Soil spatial representation is shown to have a significant role on runoff coefficients and on the spatial variability of saturation dynamics. Simulated soil saturation is found to be strongly related with soil depth and initial storage deficit maps, due to a full saturation of most of the area at the end of the event. When activated, the signature of subsurface lateral flow is also visible in the spatial patterns of soil saturation with higher values concentrating along the river network. However, the data currently available do not allow the assessment of both patterns. The paper concludes with a set of

  3. Simulating extreme low-discharge events for the Rhine using a stochastic model

    Science.gov (United States)

    Macian-Sorribes, Hector; Mens, Marjolein; Schasfoort, Femke; Diermanse, Ferdinand; Pulido-Velazquez, Manuel

    2017-04-01

    The specific features of hydrological droughts make them more difficult to be analysed than other water-related phenomena: longer time scales (months to several years) so less historical events are available, and the drought severity and associate damage depends on a combination of variables with no clear prevalence (e.g., total water deficit, maximum deficit and duration). As part of drought risk analysis, which aims to provide insight into the variability of hydrological conditions and associated socio-economic impacts, long synthetic time series should therefore be developed. In this contribution, we increase the length of the available inflow time series using stochastic autoregressive modelling. This enhancement could improve the characterization of the extreme range and can define extreme droughts with similar periods of return but different patterns that can lead to distinctly different damages. The methodology consists of: 1) fitting an autoregressive model (AR, ARMA…) to the available records; 2) generating extended time series (thousands of years); 3) performing a frequency analysis with different characteristic variables (total, deficit, maximum deficit and so on); and 4) selecting extreme drought events associated with different characteristic variables and return periods. The methodology was applied to the Rhine river discharge at location Lobith, where the Rhine enters The Netherlands. A monthly ARMA(1,1) autoregressive model with seasonally varying parameters was fitted and successfully validated to the historical records available since year 1901. The maximum monthly deficit with respect to a threshold value of 1800 m3/s and the average discharge for a given time span in m3/s were chosen as indicators to identify drought periods. A synthetic series of 10,000 years of discharges was generated using the validated ARMA model. Two time spans were considered in the analysis: the whole calendar year and the half-year period between April and September

  4. (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

  5. Extreme fire events are related to previous-year surface moisture conditions in permafrost-underlain larch forests of Siberia

    International Nuclear Information System (INIS)

    Forkel, Matthias; Beer, Christian; Thonicke, Kirsten; Cramer, Wolfgang; Bartalev, Sergey; Schmullius, Christiane

    2012-01-01

    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 km 2 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)

  6. A Flexible Nonlinear Modelling Framework for Nonstationary Generalized Extreme Value Analysis in Hydrology and Climatology

    Science.gov (United States)

    Cannon, A. J.

    2009-12-01

    Parameters in a Generalized Extreme Value (GEV) distribution are specified as a function of covariates using a conditional density network (CDN), which is a probabilistic extension of the multilayer perceptron neural network. If the covariate is time, or is dependent on time, then the GEV-CDN model can be used to perform nonlinear, nonstationary GEV analysis of hydrological or climatological time series. Due to the flexibility of the neural network architecture, the model is capable of representing a wide range of nonstationary relationships. Model parameters are estimated by generalized maximum likelihood, an approach that is tailored to the estimation of GEV parameters from geophysical time series. Model complexity is identified using the Bayesian information criterion and the Akaike information criterion with small sample size correction. Monte Carlo simulations are used to validate GEV-CDN performance on four simple synthetic problems. The model is then demonstrated on precipitation data from southern California, a series that exhibits nonstationarity due to interannual/interdecadal climatic variability. A hierarchy of models can be defined by adjusting three aspects of the GEV-CDN model architecture: (i) by specifying either a linear or a nonlinear hidden-layer activation function; (ii) by adjusting the number of hidden-layer nodes; or (iii) by disconnecting weights leading to output-layer nodes. To illustrate, five GEV-CDN models are shown here in order of increasing complexity for the case of a single covariate, which, in this case, is assumed to be time. The shape parameter is assumed to be constant in all models, although this is not a requirement of the GEV-CDN framework.

  7. Impact of climate change on hydrological extremes in Dobrogea region, Romania

    Science.gov (United States)

    Buta, Constantin; Maftei, Carmen

    2015-04-01

    Over time, Dobrogea territory has faced with fluctuations more or less severe in terms of basic parameters such as temperature, precipitations and annual discharges of rivers. It is highlighted the trend of aridity in the area, because of the fact that Dobrogea receives small amounts of water, ranging between 200-450 mm/year, with annual average temperatures lying around and above the average of 11°C. This fact is also proceeding from the many studies realized by other researchers. For this area there are also characteristic torrents (form of rainfall during the summer), the storms and floods accompanying these torrents of water on the narrow valleys, often intermittent, sometimes causing significant damage and even fatalities. Torrential rainfalls and flash floods are sometimes very strong and produce catastrophic damages, as happened at Constanta (in 2001), at Tulcea (in 13.07.2004 and in 29.08.2004), at Tuzla, Pantelimon, Agigea and others. At the opposite pole of the sporadic excess rainfall is drought, which is the largest meteorological phenomenon (both in time and in space) and the most obvious in Dobrogea climate. Drought represents the main argument of semi aridity of this region and the most visible image component which is observed by the inhabitants of this environment. Correlation and study of hydro-meteorological extremes is performed using indices that take into account meteorological and hydrological parameters such as precipitations, temperature, discharges of rivers etc. Hydro-meteorological indices used for this study are: Angot rainfall index; Peguy Climograms; de Martonne drought index; Thornthwaite index Moduli coefficients and Deciles. According to the studied indices, for the accomplishment of this present paper, we can say that Dobrogea is among the driest regions in the country. History of drought in Romania includes many dry years, of which are mentioned: 1894, 1888, 1904, 1918, 1934, 1945, but the droughts years with greater durations

  8. Changes in extreme events and the potential impacts on human health.

    Science.gov (United States)

    Bell, Jesse E; Brown, Claudia Langford; Conlon, Kathryn; Herring, Stephanie; Kunkel, Kenneth E; Lawrimore, Jay; Luber, George; Schreck, Carl; Smith, Adam; Uejio, Christopher

    2018-04-01

    Extreme weather and climate-related events affect human health by causing death, injury, and illness, as well as having large socioeconomic impacts. Climate change has caused changes in extreme event frequency, intensity, and geographic distribution, and will continue to be a driver for change in the future. Some of these events include heat waves, droughts, wildfires, dust storms, flooding rains, coastal flooding, storm surges, and hurricanes. The pathways connecting extreme events to health outcomes and economic losses can be diverse and complex. The difficulty in predicting these relationships comes from the local societal and environmental factors that affect disease burden. More information is needed about the impacts of climate change on public health and economies to effectively plan for and adapt to climate change. This paper describes some of the ways extreme events are changing and provides examples of the potential impacts on human health and infrastructure. It also identifies key research gaps to be addressed to improve the resilience of public health to extreme events in the future. Extreme weather and climate events affect human health by causing death, injury, and illness, as well as having large socioeconomic impacts. Climate change has caused changes in extreme event frequency, intensity, and geographic distribution, and will continue to be a driver for change in the future. Some of these events include heat waves, droughts, wildfires, flooding rains, coastal flooding, surges, and hurricanes. The pathways connecting extreme events to health outcomes and economic losses can be diverse and complex. The difficulty in predicting these relationships comes from the local societal and environmental factors that affect disease burden.

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

    Indian Academy of Sciences (India)

    The diagnostic event signatures include the extent and elevation of the deposits, as well as morphologic similarity ... Historical archives of the origin, timing, and impact of tsunamis, storms, and floods along the mar- gins of ... High-resolution GPR studies (by the IIT Madras group) of erosional signatures from the beach ridge.

  10. Climate variations and changes in extreme climate events in Russia

    International Nuclear Information System (INIS)

    Bulygina, O N; Razuvaev, V N; Korshunova, N N; Groisman, P Ya

    2007-01-01

    Daily temperature (mean, minimum and maximum) and atmospheric precipitation data from 857 stations are used to analyze variations in the space-time distribution of extreme temperatures and precipitation across Russia during the past six decades. The seasonal numbers of days (N) when daily air temperatures (diurnal temperature range, precipitation) were higher or lower than selected thresholds are used as indices of climatic extremes. Linear trends in N are calculated for each station for the time period of interest. The seasonal numbers of days (for each season) with maximum temperatures higher than the 95th percentile have increased over most of Russia, with minimum temperatures lower than the 5th percentile having decreased. A tendency for the decrease in the number of days with abnormally high diurnal temperature range is observed over most of Russia. In individual regions of Russia, however, a tendency for an increasing number of days with a large diurnal amplitude is found. The largest tendency for increasing number of days with heavy precipitation is observed in winter in Western Siberia and Yakutia

  11. Cause and Properties of the Extreme Space Weather Event of 2012 July 23

    Science.gov (United States)

    Liu, Y. D.; Luhmann, J. G.; Kajdic, P.; Kilpua, E.; Lugaz, N.; Nitta, N.; Lavraud, B.; Bale, S. D.; Farrugia, C. J.; Galvin, A. B.

    2013-12-01

    Extreme space weather refers to extreme conditions in space driven by solar eruptions and subsequent disturbances in interplanetary space, or otherwise called solar superstorms. Understanding extreme space weather events is becoming ever more vital, as the vulnerability of our society and its technological infrastructure to space weather has increased dramatically. Instances of extreme space weather, however, are very rare by definition and therefore are difficult to study. Here we report and investigate an extreme event, which occurred on 2012 July 23 with a maximum speed of about 3050 km/s near the Sun. This event, with complete modern remote sensing and in situ observations from multiple vantage points, provides an unprecedented opportunity to study the cause and consequences of extreme space weather. It produced a superfast shock with a peak solar wind speed of 2246 km/s and a superstrong magnetic cloud with a peak magnetic field of 109 nT observed near 1 AU at STEREO A. The record solar wind speed and magnetic field would produce a record geomagnetic storm since the space era with a minimum Dst of -1200 - -600 nT, if this event hit the Earth. We demonstrate how successive coronal mass ejections (CMEs) can be enhanced into a solar superstorm as they interact en route from the Sun to 1 AU. These results not only provide a benchmark for studies of extreme space weather, but also present a new view of how an extreme space weather event can be generated from usual solar eruptions.

  12. Influence of an extreme high water event on survival, reproduction, and distribution of snail kites in Florida, USA

    Science.gov (United States)

    Bennetts, R.E.; Kitchens, W.M.; Dreitz, V.J.

    2002-01-01

    Hydrology frequently has been reported as the environmental variable having the greatest influence on Florida snail kite (Rostrhamus sociabilis) populations. Although drought has received the most attention, high-water conditions also have been reported to affect kites. Years of high water generally have been reported to be favorable for nesting, although prolonged high water may be detrimental to sustaining suitable habitat. During 1994 and 1995, southern Florida experienced an extreme high water event. This event enabled us to compare survival, nesting success, number of young per successful nest, and spatial distribution of nesting before, during, and after the event. We found no evidence of an effect (either negative or positive) on survival of adult kites. In contrast, juvenile kites experienced the highest survival during the event, although our data suggest greater annual variability than can be explained by the event alone. We found no evidence of an effect of the high water event on nest success or number of young per successful nest. Nest success was highest during the event in the southern portion of the range but was quite similar to other years, both before and after the event. Our data do indicate a substantial shift in the spatial distribution of nesting birds. During the event, nesting activity shifted to higher elevations (i.e., shallower water) in the major nesting areas of the Everglades region. Nesting also occurred in Big Cypress National Preserve during the event, which is typically too dry to support nesting kites. Thus, our data indicate a potential short-term benefit of increased juvenile survival and an expansion of nesting habitat. However, the deterioration of habitat quality from prolonged high water precludes any recommendation for such conditions to be maintained for extended periods. ?? 2002, The Society of Wetland Scientists.

  13. The relationship between extreme weather events and crop losses in central Taiwan

    Science.gov (United States)

    Lai, Li-Wei

    2017-09-01

    The frequency of extreme weather events, which cause severe crop losses, is increasing. This study investigates the relationship between crop losses and extreme weather events in central Taiwan from 2003 to 2015 and determines the main factors influencing crop losses. Data regarding the crop loss area and meteorological information were obtained from government agencies. The crops were categorised into the following five groups: `grains', `vegetables', `fruits', `flowers' and `other crops'. The extreme weather events and their synoptic weather patterns were categorised into six and five groups, respectively. The data were analysed using the z score, correlation coefficient and stepwise regression model. The results show that typhoons had the highest frequency of all extreme weather events (58.3%). The largest crop loss area (4.09%) was caused by two typhoons and foehn wind in succession. Extreme wind speed coupled with heavy rainfall is an important factor affecting the losses in the grain and vegetable groups. Extreme wind speed is a common variable that affects the loss of `grains', `vegetables', `fruits' and `flowers'. Consecutive extreme weather events caused greater crop losses than individual events. Crops with long production times suffered greater losses than those with short production times. This suggests that crops with physical structures that can be easily damaged and long production times would benefit from protected cultivation to maintain food security.

  14. 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

    2016-01-01

    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

  15. Uncertainty related to Environmental Data and Estimated Extreme Events

    DEFF Research Database (Denmark)

    Burcharth, H. F.

    The design loads on rubble mound breakwaters are almost entirely determined by the environmental conditions, i.e. sea state, water levels, sea bed characteristics, etc. It is the objective of sub-group B to identify the most important environmental parameters and evaluate the related uncertainties...... 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....... Consequently this report deals mainly with each parameter separately. Multi parameter problems are briefly discussed in section 9. It is important to notice that the quantified uncertainties reported in section 7.7 represent what might be regarded as typical figures to be used only when no more qualified...

  16. Extreme-event geoelectric hazard maps: Chapter 9

    Science.gov (United States)

    Love, Jeffrey J.; Bedrosian, Paul A.

    2018-01-01

    Maps of geoelectric amplitude covering about half the continental United States are presented that will be exceeded, on average, once per century in response to an extreme-intensity geomagnetic disturbance. These maps are constructed using an empirical parameterization of induction: convolving latitude-dependent statistical maps of extreme-value geomagnetic disturbances, obtained from decades of 1-minute magnetic observatory data, with local estimates of Earth-surface impedance obtained at discrete geographic sites from magnetotelluric surveys. Geoelectric amplitudes are estimated for geomagnetic waveforms having a 240-s (and 1200-s) sinusoidal period and amplitudes over 10 min (1 h) that exceed a once-per-century threshold. As a result of the combination of geographic differences in geomagnetic variation and Earth-surface impedance, once-per-century geoelectric amplitudes span more than two orders of magnitude and are a highly granular function of location. Specifically for north-south 240-s induction, once-per-century geoelectric amplitudes across large parts of the United States have a median value of 0.34 V/km; for east-west variation, they have a median value of 0.23 V/km. In Northern Minnesota, amplitudes exceed 14.00 V/km for north-south geomagnetic variation (23.34 V/km for east-west variation), while just over 100 km away, amplitudes are only 0.08 V/km (0.02 V/km). At some sites in the northern-central United States, once-per-century geoelectric amplitudes exceed the 2 V/km realized in Québec during the March 1989 storm.

  17. Improving Simulations of Extreme Flows by Coupling a Physically-based Hydrologic Model with a Machine Learning Model

    Science.gov (United States)

    Mohammed, K.; Islam, A. S.; Khan, M. J. U.; Das, M. K.

    2017-12-01

    With the large number of hydrologic models presently available along with the global weather and geographic datasets, streamflows of almost any river in the world can be easily modeled. And if a reasonable amount of observed data from that river is available, then simulations of high accuracy can sometimes be performed after calibrating the model parameters against those observed data through inverse modeling. Although such calibrated models can succeed in simulating the general trend or mean of the observed flows very well, more often than not they fail to adequately simulate the extreme flows. This causes difficulty in tasks such as generating reliable projections of future changes in extreme flows due to climate change, which is obviously an important task due to floods and droughts being closely connected to people's lives and livelihoods. We propose an approach where the outputs of a physically-based hydrologic model are used as an input to a machine learning model to try and better simulate the extreme flows. To demonstrate this offline-coupling approach, the Soil and Water Assessment Tool (SWAT) was selected as the physically-based hydrologic model, the Artificial Neural Network (ANN) as the machine learning model and the Ganges-Brahmaputra-Meghna (GBM) river system as the study area. The GBM river system, located in South Asia, is the third largest in the world in terms of freshwater generated and forms the largest delta in the world. The flows of the GBM rivers were simulated separately in order to test the performance of this proposed approach in accurately simulating the extreme flows generated by different basins that vary in size, climate, hydrology and anthropogenic intervention on stream networks. Results show that by post-processing the simulated flows of the SWAT models with ANN models, simulations of extreme flows can be significantly improved. The mean absolute errors in simulating annual maximum/minimum daily flows were minimized from 4967

  18. Developing an approach to effectively use super ensemble experiments for the projection of hydrological extremes under climate change

    Science.gov (United States)

    Watanabe, S.; Kim, H.; Utsumi, N.

    2017-12-01

    This study aims to develop a new approach which projects hydrology under climate change using super ensemble experiments. The use of multiple ensemble is essential for the estimation of extreme, which is a major issue in the impact assessment of climate change. Hence, the super ensemble experiments are recently conducted by some research programs. While it is necessary to use multiple ensemble, the multiple calculations of hydrological simulation for each output of ensemble simulations needs considerable calculation costs. To effectively use the super ensemble experiments, we adopt a strategy to use runoff projected by climate models directly. The general approach of hydrological projection is to conduct hydrological model simulations which include land-surface and river routing process using atmospheric boundary conditions projected by climate models as inputs. This study, on the other hand, simulates only river routing model using runoff projected by climate models. In general, the climate model output is systematically biased so that a preprocessing which corrects such bias is necessary for impact assessments. Various bias correction methods have been proposed, but, to the best of our knowledge, no method has proposed for variables other than surface meteorology. Here, we newly propose a method for utilizing the projected future runoff directly. The developed method estimates and corrects the bias based on the pseudo-observation which is a result of retrospective offline simulation. We show an application of this approach to the super ensemble experiments conducted under the program of Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI). More than 400 ensemble experiments from multiple climate models are available. The results of the validation using historical simulations by HAPPI indicates that the output of this approach can effectively reproduce retrospective runoff variability. Likewise, the bias of runoff from super ensemble climate

  19. The progress of hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Chow, V T [University of Illinois, Urbana, IL (United States)

    1967-05-15

    This paper discusses mainly the challenge of hydrology, recent activities, events, and major problems in hydrology, and advances in hydrological techniques. New scientific knowledge and techniques developed in many modern scientific disciplines, and the recognition of the importance of hydrology in water-resources development enable and encourage the hydrologist to advance scientific hydrology. Many programmes to promote hydrology and to expand its attendant activities have been developed in recent years. Therefore, the activities in the United States of America, such as the Universities Council on Water Resources and the President's Water for Peace Programme, and the programmes in the International Hydrological Decade are mentioned. The most important advance in theoretical hydrology is the development of a new concept of dynamic sequential systems for the hydrological cycle, thus creating new fields of systems, parametric, and stochastic hydrology. Modern scientific instrumentation provide the hydrologist with better tools for solving his problems. The most important of these, such as electronic computers, remote sensing, and nuclear techniques are discussed. Today various major problems, both theoretical and practical, face the hydrologist. Theoretical problems concern the basic understanding of hydrological systems and the mathematical simulation and physical interpretation of hydrological phenomena. Major practical problems are numerous and diversified, but they are mostly related to the multiple-purpose development of water resources. Four central problematical subjects are discussed; namely, the effects of man on his environment, the dynamics of aqueous flow systems, hydrological transport mechanism, and groundwater hydrology. Also, the use of nuclear techniques in solving various hydrological problems is discussed. It is believed that the application of nuclear techniques would prove extremely valuable in helping solve problems, but their ultimate use in

  20. The progress of hydrology

    International Nuclear Information System (INIS)

    Chow, V.T.

    1967-01-01

    This paper discusses mainly the challenge of hydrology, recent activities, events, and major problems in hydrology, and advances in hydrological techniques. New scientific knowledge and techniques developed in many modern scientific disciplines, and the recognition of the importance of hydrology in water-resources development enable and encourage the hydrologist to advance scientific hydrology. Many programmes to promote hydrology and to expand its attendant activities have been developed in recent years. Therefore, the activities in the United States of America, such as the Universities Council on Water Resources and the President's Water for Peace Programme, and the programmes in the International Hydrological Decade are mentioned. The most important advance in theoretical hydrology is the development of a new concept of dynamic sequential systems for the hydrological cycle, thus creating new fields of systems, parametric, and stochastic hydrology. Modern scientific instrumentation provide the hydrologist with better tools for solving his problems. The most important of these, such as electronic computers, remote sensing, and nuclear techniques are discussed. Today various major problems, both theoretical and practical, face the hydrologist. Theoretical problems concern the basic understanding of hydrological systems and the mathematical simulation and physical interpretation of hydrological phenomena. Major practical problems are numerous and diversified, but they are mostly related to the multiple-purpose development of water resources. Four central problematical subjects are discussed; namely, the effects of man on his environment, the dynamics of aqueous flow systems, hydrological transport mechanism, and groundwater hydrology. Also, the use of nuclear techniques in solving various hydrological problems is discussed. It is believed that the application of nuclear techniques would prove extremely valuable in helping solve problems, but their ultimate use in

  1. Impact of environmental factors on the distribution of extreme scouring (gouging) event, Canadian Beaufort shelf

    Energy Technology Data Exchange (ETDEWEB)

    Blasco, Steve [Geological Survey of Canada, Dartmouth (Canada); Carr, Erin; Campbell, Patrick [Canadian Seabed Research Ltd., Porters Lake (Canada); Shearer, Jim [Shearer Consulting, Ottawa (Canada)

    2011-07-01

    A knowledge of the presence of scours, their dimensions and their return frequencies is highly important in the development of hydrocarbon offshore structures. Mapping surveys have identified 290 extreme scour events across the Canadian Beaufort shelf. This paper investigated the impact of environmental factors on the distribution of extreme scouring events in the Canadian Beaufort shelf. This study used the NEWBASE database of new ice scours to perform an analysis of the scours appearance mechanisms. The geotechnical zonation, the bathymetry and the shelf gradient were evaluated using these data. Estimation of the surficial sediment type, the surficial sediment thickness and sea ice regime were also made. It was found that the spatial distribution of extreme scour events is controlled by sea-ice regime, bathymetry and geotechnical zonation. The results obtained from mapping surveys suggested that the key controlling environmental factors may combine to limit the depth of extreme scour events to 5 meters.

  2. 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...

  3. Extreme events in the Dudetes Mountains - Their long-term geomorphic impact and possible controlling factors

    Czech Academy of Sciences Publication Activity Database

    Migon, P.; Hrádek, Mojmír; Parzoch, K.

    2002-01-01

    Roč. 36, č. 36 (2002), s. 29-49 ISSN 0081-6434 Institutional research plan: CEZ:AV0Z3086906 Keywords : extreme events * debris flow * landslide-floods Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  4. Lags in hydrologic recovery following an extreme drought: Assessing the roles of climate and catchment characteristics

    Science.gov (United States)

    Yang, Yuting; McVicar, Tim R.; Donohue, Randall J.; Zhang, Yongqiang; Roderick, Michael L.; Chiew, Francis H. S.; Zhang, Lu; Zhang, Junlong

    2017-06-01

    Drought, generally characterized by below-average water supply, propagates through the hydrologic system with consequent ecological and societal impacts. Compared with other drought aspects, the recovery of drought especially in the hydrological components, which directly relates to the recovery of water resources for agricultural, ecological and human needs, is less-understood. Here, taking the Millennium drought in southeast Australia (˜1997-2009) as an illustrating case, we comprehensively examined multiple aspects of the meteorological (i.e., precipitation) and hydrological (i.e., streamflow and base flow) droughts across 130 unimpaired catchments using long-term hydro-meteorological observations. Results show that the duration and intensity of the meteorological drought are both lengthened and amplified in the hydrological drought, suggesting a nonstationarity in the rainfall-runoff relationship during a prolonged drought. Additionally, we find a time lag commonly exists between the end of the meteorological droughts and the end of the hydrological drought, with the recovery of base flow showing a longer lag than the recovery of streamflow. The recovery rate of precipitation after drought was found to be the dominant factor that controls the recovery of hydrological droughts while catchment landscape (i.e., valley bottom flatness) plays an important but secondary role in controlling the lags in the hydrological recovery. Other hydro-climatic factors and catchment properties appear to have only minor influences governing hydrological drought recovery. Our findings highlight a delayed response in the terrestrial components of the hydrological cycle to precipitation after prolonged drought, and provide valuable scientific guidance to water resources management and water security assessment in regions facing future droughts.

  5. Statistics of extreme events in Chinese stock markets

    International Nuclear Information System (INIS)

    Wu Gan-Hua; Qiu Lu; Li Xin-Li; Yang Yue; Yang Hui-Jie; Jiang Yan; Stephen Mutua

    2014-01-01

    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)

  6. Power System Extreme Event Detection: The VulnerabilityFrontier

    Energy Technology Data Exchange (ETDEWEB)

    Lesieutre, Bernard C.; Pinar, Ali; Roy, Sandip

    2007-10-17

    In this work we apply graph theoretic tools to provide aclose bound on a frontier relating the number of line outages in a gridto the power disrupted by the outages. This frontier describes theboundary of a space relating the possible severity of a disturbance interms of power disruption, from zero to some maximum on the boundary, tothe number line outages involved in the event. We present the usefulnessof this analysis with a complete analysis of a 30 bus system, and presentresults for larger systems.

  7. 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

  8. Triggering extreme events at the nanoscale in photonic seas

    KAUST Repository

    Liu, Changxu; Van Der Wel, Ruben E C; Rotenberg, Nir; Kuipers, Laurens Kobus; Krauss, T. F.; Di Falco, Andrea; Fratalocchi, Andrea

    2015-01-01

    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.

  9. 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.

  10. 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.

  11. Extreme events in Italy from documentary sources: Venice as a case study

    International Nuclear Information System (INIS)

    Camuffo, D.; Pagan, E.; Colacino, M.; Enzi, S.; Cocheo, C.; Sturaro, G.

    2006-01-01

    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

  12. Statistical analysis and ANN modeling for predicting hydrological extremes under climate change scenarios: the example of a small Mediterranean agro-watershed.

    Science.gov (United States)

    Kourgialas, Nektarios N; Dokou, Zoi; Karatzas, George P

    2015-05-01

    The purpose of this study was to create a modeling management tool for the simulation of extreme flow events under current and future climatic conditions. This tool is a combination of different components and can be applied in complex hydrogeological river basins, where frequent flood and drought phenomena occur. The first component is the statistical analysis of the available hydro-meteorological data. Specifically, principal components analysis was performed in order to quantify the importance of the hydro-meteorological parameters that affect the generation of extreme events. The second component is a prediction-forecasting artificial neural network (ANN) model that simulates, accurately and efficiently, river flow on an hourly basis. This model is based on a methodology that attempts to resolve a very difficult problem related to the accurate estimation of extreme flows. For this purpose, the available measurements (5 years of hourly data) were divided in two subsets: one for the dry and one for the wet periods of the hydrological year. This way, two ANNs were created, trained, tested and validated for a complex Mediterranean river basin in Crete, Greece. As part of the second management component a statistical downscaling tool was used for the creation of meteorological data according to the higher and lower emission climate change scenarios A2 and B1. These data are used as input in the ANN for the forecasting of river flow for the next two decades. The final component is the application of a meteorological index on the measured and forecasted precipitation and flow data, in order to assess the severity and duration of extreme events. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Quantifying the Extremity of Windstorms for Regions Featuring Infrequent Events

    Science.gov (United States)

    Walz, M. A.; Leckebusch, G. C.; Kruschke, T.; Rust, H.; Ulbrich, U.

    2017-12-01

    This paper introduces the Distribution-Independent Storm Severity Index (DI-SSI). The DI-SSI represents an approach to quantify the severity of exceptional surface wind speeds of large scale windstorms that is complementary to the Storm Severity Index (SSI) introduced by Leckebusch et al. (2008). While the SSI approaches the extremeness of a storm from a meteorological and potential loss (impact) perspective, the DI-SSI defines the severity in a more climatological perspective. The idea is to assign equal index values to wind speeds of the same singularity (e.g. the 99th percentile) under consideration of the shape of the tail of the local wind speed climatology. Especially in regions at the edge of the classical storm track the DI-SSI shows more equitable severity estimates, e.g. for the extra-tropical cyclone Klaus. Here were compare the integral severity indices for several prominent windstorm in the European domain and discuss the advantages and disadvantages of the respective index. In order to compare the indices, their relation with the North Atlantic Oscillation (NAO) is studied, which is one of the main large scale drivers for the intensity of European windstorms. Additionally we can identify a significant relationship between the frequency and intensity of windstorms for large parts of the European domain.

  14. The magnitude and effects of extreme solar particle events

    Directory of Open Access Journals (Sweden)

    Jiggens Piers

    2014-06-01

    Full Text Available The solar energetic particle (SEP radiation environment is an important consideration for spacecraft design, spacecraft mission planning and human spaceflight. Herein is presented an investigation into the likely severity of effects of a very large Solar Particle Event (SPE on technology and humans in space. Fluences for SPEs derived using statistical models are compared to historical SPEs to verify their appropriateness for use in the analysis which follows. By combining environment tools with tools to model effects behind varying layers of spacecraft shielding it is possible to predict what impact a large SPE would be likely to have on a spacecraft in Near-Earth interplanetary space or geostationary Earth orbit. Also presented is a comparison of results generated using the traditional method of inputting the environment spectra, determined using a statistical model, into effects tools and a new method developed as part of the ESA SEPEM Project allowing for the creation of an effect time series on which statistics, previously applied to the flux data, can be run directly. The SPE environment spectra is determined and presented as energy integrated proton fluence (cm−2 as a function of particle energy (in MeV. This is input into the SHIELDOSE-2, MULASSIS, NIEL, GRAS and SEU effects tools to provide the output results. In the case of the new method for analysis, the flux time series is fed directly into the MULASSIS and GEMAT tools integrated into the SEPEM system. The output effect quantities include total ionising dose (in rads, non-ionising energy loss (MeV g−1, single event upsets (upsets/bit and the dose in humans compared to established limits for stochastic (or cancer-causing effects and tissue reactions (such as acute radiation sickness in humans given in grey-equivalent and sieverts respectively.

  15. 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.

  16. Climate Change Extreme Events: Meeting the Information Needs of Water Resource Managers

    Science.gov (United States)

    Quay, R.; Garfin, G. M.; Dominguez, F.; Hirschboeck, K. K.; Woodhouse, C. A.; Guido, Z.; White, D. D.

    2013-12-01

    Information about climate has long been used by water managers to develop short term and long term plans and strategies for regional and local water resources. Inherent within longer term forecasts is an element of uncertainty, which is particularly evident in Global Climate model results for precipitation. For example in the southwest estimates in the flow of the Colorado River based on GCM results indicate changes from 120% or current flow to 60%. Many water resource managers are now using global climate model down scaled estimates results as indications of potential climate change as part of that planning. They are addressing the uncertainty within these estimates by using an anticipatory planning approach looking at a range of possible futures. One aspect of climate that is important for such planning are estimates of future extreme storm (short term) and drought (long term) events. However, the climate science of future possible changes in extreme events is less mature than general climate change science. At a recent workshop among climate scientists and water managers in the southwest, it was concluded the science of climate change extreme events is at least a decade away from being robust enough to be useful for water managers in their water resource management activities. However, it was proposed that there are existing estimates and records of past flooding and drought events that could be combined with general climate change science to create possible future events. These derived events could be of sufficient detail to be used by water resource managers until such time that the science of extreme events is able to provide more detailed estimates. Based on the results of this workshop and other work being done by the Decision Center for a Desert City at Arizona State University and the Climate Assessment for the Southwest center at University of Arizona., this article will 1) review what are the extreme event data needs of Water Resource Managers in the

  17. 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

  18. EVT in electricity price modeling : extreme value theory not only on the extreme events

    International Nuclear Information System (INIS)

    Marossy, Z.

    2007-01-01

    The extreme value theory (EVT) is commonly used in electricity and financial risk modeling. In this study, EVT was used to model the distribution of electricity prices. The model was built on the price formation in electricity auction markets. This paper reviewed the 3 main modeling approaches used to describe the distribution of electricity prices. The first approach is based on a stochastic model of the electricity price time series and uses this stochastic model to generate the given distribution. The second approach involves electricity supply and demand factors that determine the price distribution. The third approach involves agent-based models which use simulation techniques to write down the price distribution. A fourth modeling approach was then proposed to describe the distribution of electricity prices. The new approach determines the distribution of electricity prices directly without knowing anything about the data generating process or market driving forces. Empirical data confirmed that the distribution of electricity prices have a generalized extreme value (GEV) distribution. 8 refs., 2 tabs., 5 figs

  19. Economic Evaluations of the Health Impacts of Weather-Related Extreme Events: A Scoping Review

    Science.gov (United States)

    Schmitt, Laetitia H. M.; Graham, Hilary M.; White, Piran C. L.

    2016-01-01

    The frequency and severity of extreme events is expected to increase under climate change. There is a need to understand the economic consequences of human exposure to these extreme events, to underpin decisions on risk reduction. We undertook a scoping review of economic evaluations of the adverse health effects from exposure to weather-related extreme events. We searched PubMed, Embase and Web of Science databases with no restrictions to the type of evaluations. Twenty studies were included, most of which were recently published. Most studies have been undertaken in the U.S. (nine studies) or Asia (seven studies), whereas we found no studies in Africa, Central and Latin America nor the Middle East. Extreme temperatures accounted for more than a third of the pool of studies (seven studies), closely followed by flooding (six studies). No economic study was found on drought. Whilst studies were heterogeneous in terms of objectives and methodology, they clearly indicate that extreme events will become a pressing public health issue with strong welfare and distributional implications. The current body of evidence, however, provides little information to support decisions on the allocation of scarce resources between risk reduction options. In particular, the review highlights a significant lack of research attention to the potential cost-effectiveness of interventions that exploit the capacity of natural ecosystems to reduce our exposure to, or ameliorate the consequences of, extreme events. PMID:27834843

  20. Economic Evaluations of the Health Impacts of Weather-Related Extreme Events: A Scoping Review

    Directory of Open Access Journals (Sweden)

    Laetitia H. M. Schmitt

    2016-11-01

    Full Text Available The frequency and severity of extreme events is expected to increase under climate change. There is a need to understand the economic consequences of human exposure to these extreme events, to underpin decisions on risk reduction. We undertook a scoping review of economic evaluations of the adverse health effects from exposure to weather-related extreme events. We searched PubMed, Embase and Web of Science databases with no restrictions to the type of evaluations. Twenty studies were included, most of which were recently published. Most studies have been undertaken in the U.S. (nine studies or Asia (seven studies, whereas we found no studies in Africa, Central and Latin America nor the Middle East. Extreme temperatures accounted for more than a third of the pool of studies (seven studies, closely followed by flooding (six studies. No economic study was found on drought. Whilst studies were heterogeneous in terms of objectives and methodology, they clearly indicate that extreme events will become a pressing public health issue with strong welfare and distributional implications. The current body of evidence, however, provides little information to support decisions on the allocation of scarce resources between risk reduction options. In particular, the review highlights a significant lack of research attention to the potential cost-effectiveness of interventions that exploit the capacity of natural ecosystems to reduce our exposure to, or ameliorate the consequences of, extreme events.

  1. Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events.

    Science.gov (United States)

    Axelsson, Charles; van Sebille, Erik

    2017-11-15

    The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic leakage is extremely pertinent. Here, we explore why and how coastal cities can reduce macroplastic leakages during extreme rainfall events. Using nine global cities as a basis, we establish that while cities actively create policies that reduce plastic leakages, more needs to be done. Nonetheless, these policies are economically, socially and environmentally cobeneficial to the city environment. While the lack of political engagement and economic concerns limit these policies, lacking social motivation and engagement is the largest limitation towards implementing policy. We recommend cities to incentivize citizen and municipal engagement with responsible usage of plastics, cleaning the environment and preparing for future extreme rainfall events. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  2. 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

  3. Assessment of Observational Uncertainty in Extreme Precipitation Events over the Continental United States

    Science.gov (United States)

    Slinskey, E. A.; Loikith, P. C.; Waliser, D. E.; Goodman, A.

    2017-12-01

    Extreme precipitation events are associated with numerous societal and environmental impacts. Furthermore, anthropogenic climate change is projected to alter precipitation intensity across portions of the Continental United States (CONUS). Therefore, a spatial understanding and intuitive means of monitoring extreme precipitation over time is critical. Towards this end, we apply an event-based indicator, developed as a part of NASA's support of the ongoing efforts of the US National Climate Assessment, which assigns categories to extreme precipitation events based on 3-day storm totals as a basis for dataset intercomparison. To assess observational uncertainty across a wide range of historical precipitation measurement approaches, we intercompare in situ station data from the Global Historical Climatology Network (GHCN), satellite-derived precipitation data from NASA's Tropical Rainfall Measuring Mission (TRMM), gridded in situ station data from the Parameter-elevation Regressions on Independent Slopes Model (PRISM), global reanalysis from NASA's Modern Era Retrospective-Analysis version 2 (MERRA 2), and regional reanalysis with gauge data assimilation from NCEP's North American Regional Reanalysis (NARR). Results suggest considerable variability across the five-dataset suite in the frequency, spatial extent, and magnitude of extreme precipitation events. Consistent with expectations, higher resolution datasets were found to resemble station data best and capture a greater frequency of high-end extreme events relative to lower spatial resolution datasets. The degree of dataset agreement varies regionally, however all datasets successfully capture the seasonal cycle of precipitation extremes across the CONUS. These intercomparison results provide additional insight about observational uncertainty and the ability of a range of precipitation measurement and analysis products to capture extreme precipitation event climatology. While the event category threshold is fixed

  4. [Extreme Climatic Events in the Altai Republic According to Dendrochronological Data].

    Science.gov (United States)

    Barinov, V V; Myglan, V S; Nazarov, A N; Vaganov, E A; Agatova, A R; Nepop, R K

    2016-01-01

    The results of dating of extreme climatic events by damage to the anatomical structure and missing tree rings of the Siberian larch in the upper forest boundary of the Altai Republic are given. An analysis of the spatial distribution of the revealed dates over seven plots (Kokcy, Chind, Ak-ha, Jelo, Tute, Tara, and Sukor) allowed us to distinguish the extreme events on interregional (1700, 1783, 1788, 1812, 1814, 1884), regional (1724, 1775, 1784, 1835, 1840, 1847, 1850, 1852, 1854, 1869, 1871, 1910, 1917, 1927, 1938, 1958, 1961), and local (1702, 1736, 1751, 1785, 1842, 1843,1874, 1885, 1886, 1919, 2007, and 2009) scales. It was shown that the events of an interregional scale correspond with the dates of major volcanic eruptions (Grimsvotn, Lakagigar, Etna, Awu, Tambora, Soufriere St. Vinsent, Mayon, and Krakatau volcanos) and extreme climatic events, crop failures, lean years, etc., registered in historical sources.

  5. Implications of climate change on hydrological extremes in the Blue Nile basin: A review

    Directory of Open Access Journals (Sweden)

    Meron Teferi Taye

    2015-09-01

    New hydrological insights: The review illustrates some discrepancy among research outputs. For the historical context, this is partially related to the period and length of data analyzed and the failure to consider the influence of multi-decadal oscillations. Consequently, we show that annual cycle of Blue Nile flow has not changed in the past five decades. For the future context, discrepancy is partially attributable to the various and differing climate and hydrological models included and the downscaling techniques applied. The need to prudently consider sources of uncertainty and potential causes of bias in historical trend and climate change impact research is highlighted.

  6. Long-Term Climate Trends and Extreme Events in Northern Fennoscandia (1914–2013

    Directory of Open Access Journals (Sweden)

    Sonja Kivinen

    2017-02-01

    Full Text Available We studied climate trends and the occurrence of rare and extreme temperature and precipitation events in northern Fennoscandia in 1914–2013. Weather data were derived from nine observation stations located in Finland, Norway, Sweden and Russia. The results showed that spring and autumn temperatures and to a lesser extent summer temperatures increased significantly in the study region, the observed changes being the greatest for daily minimum temperatures. The number of frost days declined both in spring and autumn. Rarely cold winter, spring, summer and autumn seasons had a low occurrence and rarely warm spring and autumn seasons a high occurrence during the last 20-year interval (1994–2013, compared to the other 20-year intervals. That period was also characterized by a low number of days with extremely low temperature in all seasons (4–9% of all extremely cold days and a high number of April and October days with extremely high temperature (36–42% of all extremely warm days. A tendency of exceptionally high daily precipitation sums to grow even higher towards the end of the study period was also observed. To summarize, the results indicate a shortening of the cold season in northern Fennoscandia. Furthermore, the results suggest significant declines in extremely cold climate events in all seasons and increases in extremely warm climate events particularly in spring and autumn seasons.

  7. Impact of extreme weather events and climate change for health and social care systems.

    Science.gov (United States)

    Curtis, Sarah; Fair, Alistair; Wistow, Jonathan; Val, Dimitri V; Oven, Katie

    2017-12-05

    This review, commissioned by the Research Councils UK Living With Environmental Change (LWEC) programme, concerns research on the impacts on health and social care systems in the United Kingdom of extreme weather events, under conditions of climate change. Extreme weather events considered include heatwaves, coldwaves and flooding. Using a structured review method, we consider evidence regarding the currently observed and anticipated future impacts of extreme weather on health and social care systems and the potential of preparedness and adaptation measures that may enhance resilience. We highlight a number of general conclusions which are likely to be of international relevance, although the review focussed on the situation in the UK. Extreme weather events impact the operation of health services through the effects on built, social and institutional infrastructures which support health and health care, and also because of changes in service demand as extreme weather impacts on human health. Strategic planning for extreme weather and impacts on the care system should be sensitive to within country variations. Adaptation will require changes to built infrastructure systems (including transport and utilities as well as individual care facilities) and also to institutional and social infrastructure supporting the health care system. Care sector organisations, communities and individuals need to adapt their practices to improve resilience of health and health care to extreme weather. Preparedness and emergency response strategies call for action extending beyond the emergency response services, to include health and social care providers more generally.

  8. Modeling extreme (Carrington-type) space weather events using three-dimensional MHD code simulations

    Science.gov (United States)

    Ngwira, C. M.; Pulkkinen, A. A.; Kuznetsova, M. M.; Glocer, A.

    2013-12-01

    There is growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure and systems. In the last two decades, significant progress has been made towards the modeling of space weather events. Three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, and have played a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for existing global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events that have a ground footprint comparable (or larger) to the Carrington superstorm. Results are presented for an initial simulation run with ``very extreme'' constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated ground induced geoelectric field to such extreme driving conditions. We also discuss the results and what they might mean for the accuracy of the simulations. The model is further tested using input data for an observed space weather event to verify the MHD model consistence and to draw guidance for future work. This extreme space weather MHD model is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in earth conductors such as power transmission grids.

  9. 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.

  10. An observational and modeling study of the August 2017 Florida climate extreme event.

    Science.gov (United States)

    Konduru, R.; Singh, V.; Routray, A.

    2017-12-01

    A special report on the climate extremes by the Intergovernmental Panel on Climate Change (IPCC) elucidates that the sole cause of disasters is due to the exposure and vulnerability of the human and natural system to the climate extremes. The cause of such a climate extreme could be anthropogenic or non-anthropogenic. Therefore, it is challenging to discern the critical factor of influence for a particular climate extreme. Such kind of perceptive study with reasonable confidence on climate extreme events is possible only if there exist any past case studies. A similar rarest climate extreme problem encountered in the case of Houston floods and extreme rainfall over Florida in August 2017. A continuum of hurricanes like Harvey and Irma targeted the Florida region and caused catastrophe. Due to the rarity of August 2017 Florida climate extreme event, it requires the in-depth study on this case. To understand the multi-faceted nature of the event, a study on the development of the Harvey hurricane and its progression and dynamics is significant. Current article focus on the observational and modeling study on the Harvey hurricane. A global model named as NCUM (The global UK Met office Unified Model (UM) operational at National Center for Medium Range Weather Forecasting, India, was utilized to simulate the Harvey hurricane. The simulated rainfall and wind fields were compared with the observational datasets like Tropical Rainfall Measuring Mission rainfall datasets and Era-Interim wind fields. The National Centre for Environmental Prediction (NCEP) automated tracking system was utilized to track the Harvey hurricane, and the tracks were analyzed statistically for different forecasts concerning the Harvey hurricane track of Joint Typhon Warning Centre. Further, the current study will be continued to investigate the atmospheric processes involved in the August 2017 Florida climate extreme event.

  11. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes

    NARCIS (Netherlands)

    Lutz, A.; Immerzeel, W.W.; Kraaijenbrink, P.D.A.; Shresta, A.B.; Bierkens, M.F.P.

    2016-01-01

    The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically

  13. Living with extreme weather events - perspectives from climatology, geomorphological analysis, chronicles and opinion polls

    Science.gov (United States)

    Auer, I.; Kirchengast, A.; Proske, H.

    2009-09-01

    The ongoing climate change debate focuses more and more on changing extreme events. Information on past events can be derived from a number of sources, such as instrumental data, residual impacts in the landscape, but also chronicles and people's memories. A project called "A Tale of Two Valleys” within the framework of the research program "proVision” allowed to study past extreme events in two inner-alpine valleys from the sources mentioned before. Instrumental climate time series provided information for the past 200 years, however great attention had to be given to the homogeneity of the series. To derive homogenized time series of selected climate change indices methods like HOCLIS and Vincent have been applied. Trend analyses of climate change indices inform about increase or decrease of extreme events. Traces of major geomorphodynamic processes of the past (e.g. rockfalls, landslides, debris flows) which were triggered or affected by extreme weather events are still apparent in the landscape and could be evaluated by geomorphological analysis using remote sensing and field data. Regional chronicles provided additional knowledge and covered longer periods back in time, however compared to meteorological time series they enclose a high degree of subjectivity and intermittent recordings cannot be obviated. Finally, questionnaires and oral history complemented our picture of past extreme weather events. People were differently affected and have different memories of it. The joint analyses of these four data sources showed agreement to some extent, however also showed some reasonable differences: meteorological data are point measurements only with a sometimes too coarse temporal resolution. Due to land-use changes and improved constructional measures the impact of an extreme meteorological event may be different today compared to earlier times.

  14. Development of a Historical Hydrological online research and application platform for Switzerland - Historical Hydrological Atlas of Switzerland (HHAS)

    Science.gov (United States)

    Wetter, Oliver

    2017-04-01

    It is planned to develop and maintain a historical hydrological online platform for Switzerland, which shall be specially designed for the needs of research and federal, cantonal or private institutions being interested in hydrological risk assessment and protection measures. The aim is on the one hand to facilitate the access to raw data which generally is needed for further historical hydrological reconstruction and quantification, so that future research will be achieved in significantly shorter time. On the other hand, new historical hydrological research results shall be continuously included in order to establish this platform as a useful tool for the assessment of hydrological risk by including the long term experience of reconstructed pre-instrumental hydrological extreme events like floods and droughts. Meteorological parameters that may trigger extreme hydrological events, like monthly or seasonally resolved reconstructions of temperature and precipitation shall be made accessible in this platform as well. The ultimate goal will be to homogenise the reconstructed hydrological extreme events which usually appeared in the pre anthropogenic influence period under different climatological as well as different hydrological regimes and topographical conditions with the present day state. Long term changes of reconstructed small- to extreme flood seasonality, based on municipal accounting records, will be included in the platform as well. This helps - in combination with the before mentioned meteorological parameters - to provide an increased understanding of the major changes in the generally complex overall system that finally causes hydrological extreme events. The goal of my presentation at the Historical Climatology session is to give an overview about the applied historical climatological and historical hydrological methodologies that are applied on the historical raw data (evidence) to reconstruct pre instrumental hydrological events and meteorological

  15. Unveiling non-stationary coupling between Amazon and ocean during recent extreme events

    Science.gov (United States)

    Ramos, Antônio M. de T.; Zou, Yong; de Oliveira, Gilvan Sampaio; Kurths, Jürgen; Macau, Elbert E. N.

    2018-02-01

    The interplay between extreme events in the Amazon's precipitation and the anomaly in the temperature of the surrounding oceans is not fully understood, especially its causal relations. In this paper, we investigate the climatic interaction between these regions from 1999 until 2012 using modern tools of complex system science. We identify the time scale of the coupling quantitatively and unveil the non-stationary influence of the ocean's temperature. The findings show consistently the distinctions between the coupling in the recent major extreme events in Amazonia, such as the two droughts that happened in 2005 and 2010 and the three floods during 1999, 2009 and 2012. Interestingly, the results also reveal the influence over the anomalous precipitation of Southwest Amazon has become increasingly lagged. The analysis can shed light on the underlying dynamics of the climate network system and consequently can improve predictions of extreme rainfall events.

  16. Extreme wildfire events are linked to global-change-type droughts in the northern Mediterranean

    Science.gov (United States)

    Ruffault, Julien; Curt, Thomas; Martin-StPaul, Nicolas K.; Moron, Vincent; Trigo, Ricardo M.

    2018-03-01

    Increasing drought conditions under global warming are expected to alter the frequency and distribution of large and high-intensity wildfires. However, our understanding of the impact of increasing drought on extreme wildfires events remains incomplete. Here, we analyzed the weather conditions associated with the extreme wildfires events that occurred in Mediterranean France during the exceptionally dry summers of 2003 and 2016. We identified that these fires were related to two distinct shifts in the fire weather space towards fire weather conditions that had not been explored before and resulting from specific interactions between different types of drought and different fire weather types. In 2016, a long-lasting press drought intensified wind-driven fires. In 2003, a hot drought combining a heat wave with a press drought intensified heat-induced fires. Our findings highlight that increasing drought conditions projected by climate change scenarios might affect the dryness of fuel compartments and lead to a higher frequency of extremes wildfires events.

  17. Hydrological response of a small catchment burned by experimental fire

    NARCIS (Netherlands)

    Stoof, C.R.; Vervoort, R.W.; Iwema, J.; Elsen, van den H.G.M.; Ferreira, A.J.D.; Ritsema, C.J.

    2012-01-01

    Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire in Europe are scarce, and nested approaches are rarely used. We

  18. 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].

  19. Impacts of Extreme Flooding on Hydrologic Connectivity and Water Quality in the Atlantic Coastal Plain and Implications for Vulnerable Populations

    Science.gov (United States)

    Riveros-Iregui, D. A.; Moser, H. A.; Christenson, E. C.; Gray, J.; Hedgespeth, M. L.; Jass, T. L.; Lowry, D. S.; Martin, K.; Nichols, E. G.; Stewart, J. R.; Emanuel, R. E.

    2017-12-01

    In October 2016, Hurricane Matthew brought extreme flooding to eastern North Carolina, including record regional flooding along the Lumber River and its tributaries in the North Carolina Coastal Plain. Situated in a region dominated by large-scale crop-cultivation and containing some of the highest densities of concentrated animal feeding operations (CAFOs) and animal processing operations in the U.S., the Lumber River watershed is also home to the Lumbee Tribe of American Indians. Most of the tribe's 60,000+ members live within or immediately adjacent to the 3,000 km2 watershed where they maintain deep cultural and historical connections. The region, however, also suffers from high rates of poverty and large disparities in healthcare, education, and infrastructure, conditions exacerbated by Hurricane Matthew. We summarize ongoing efforts to characterize the short- and long-term impacts of extreme flooding on water quality in (1) low gradient streams and riverine wetlands of the watershed; (2) surficial aquifers, which provide water resources for the local communities, and (3) public drinking water supplies, which derive from deeper, confined aquifers but whose infrastructure suffered widespread damage following Hurricane Matthew. Our results provide mechanistic understanding of flood-related connectivity across multiple hydrologic compartments, and provide important implications for how hydrological natural hazards combine with land use to drive water quality impacts and affect vulnerable populations.

  20. Extreme events in the Mediterranean area: A mixed deterministic-statistical approach

    International Nuclear Information System (INIS)

    Speranza, A.; Tartaglione, N.

    2006-01-01

    Statistical inference suffers for severe limitations when applied to extreme meteo-climatic events. A fundamental theorem proposes a constructive theory for a universal distribution law (the Generalized Extreme Value distribution) of extremes. Use of this theorem and of its derivations is nowadays quite common. However, when applying it, the selected events should be real extremes. In practical applications a major source of errors is the fact that there is no strict criterion for selecting extremes and, in order to fatten the statistical sample very mild selection criteria are often used. The theorem in question applies to stationary processes. When a trend is introduced, inference becomes even more problematic. Experience shows that any available a priori knowledge concerning the system can play a fundamental role in the analysis, in particular if it lowers the dimensionality of the parameter space to be explored. The inference procedures serve, then, the purpose of testing the reliability of inductive hypothesis, rather than proving them. Within the above general context, analysis of the hypothesis that the frequency and/or intensity of extreme weather events in the Mediterranean area may be changing is proposed. The analysis is based on a combined deterministic-statistical approach: dynamical analysis of intense perturbations is combined with statistical techniques in order to try to formulate the problem in such a way that meaningful conclusion may be achieved

  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. National water summary 1990-91: Hydrologic events and stream water quality

    Science.gov (United States)

    Paulson, Richard W.; Chase, Edith B.; Williams, John S.; Moody, David W.

    1993-01-01

    National Water Summary 1990-91 Hydrologic Events and Stream Water Quality was planned to complement existing Federal-State water-quality reporting to the U.S. Congress that is required by the Clean Water Act of 1972. This act, formally known as the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), and its amendments in 1977,1979,1980,1981,1983, and 1987, is the principal basis for Federal-State cooperation on maintaining and reporting on water quality in the United States. Under section 305(b) of the Clean Water Act, the States must designate uses for waterbodies, biennially assess whether the waterbodies meet designated uses, and report to the U.S. Environmental Protection Agency (EPA), which in turn summarizes the findings of the State assessments in a biennial National Water Quality Inventory report to the Congress.

  3. A New Integrated Threshold Selection Methodology for Spatial Forecast Verification of Extreme Events

    Science.gov (United States)

    Kholodovsky, V.

    2017-12-01

    Extreme weather and climate events such as heavy precipitation, heat waves and strong winds can cause extensive damage to the society in terms of human lives and financial losses. As climate changes, it is important to understand how extreme weather events may change as a result. Climate and statistical models are often independently used to model those phenomena. To better assess performance of the climate models, a variety of spatial forecast verification methods have been developed. However, spatial verification metrics that are widely used in comparing mean states, in most cases, do not have an adequate theoretical justification to benchmark extreme weather events. We proposed a new integrated threshold selection methodology for spatial forecast verification of extreme events that couples existing pattern recognition indices with high threshold choices. This integrated approach has three main steps: 1) dimension reduction; 2) geometric domain mapping; and 3) thresholds clustering. We apply this approach to an observed precipitation dataset over CONUS. The results are evaluated by displaying threshold distribution seasonally, monthly and annually. The method offers user the flexibility of selecting a high threshold that is linked to desired geometrical properties. The proposed high threshold methodology could either complement existing spatial verification methods, where threshold selection is arbitrary, or be directly applicable in extreme value theory.

  4. Control of extreme events in the bubbling onset of wave turbulence.

    Science.gov (United States)

    Galuzio, P P; Viana, R L; Lopes, S R

    2014-04-01

    We show the existence of an intermittent transition from temporal chaos to turbulence in a spatially extended dynamical system, namely, the forced and damped one-dimensional nonlinear Schrödinger equation. For some values of the forcing parameter, the system dynamics intermittently switches between ordered states and turbulent states, which may be seen as extreme events in some contexts. In a Fourier phase space, the intermittency takes place due to the loss of transversal stability of unstable periodic orbits embedded in a low-dimensional subspace. We mapped these transversely unstable regions and perturbed the system in order to significantly reduce the occurrence of extreme events of turbulence.

  5. Designing Resilient and Productive Grasses with Plasticity to Extreme Weather Events

    Science.gov (United States)

    Loka, D.; Humphreys, M.; Gwyn Jones, D.; Scullion, J.; Doonan, J.; Gasior, D.; Harper, J.; Farrell, M.; Kingston-Smith, A.; Dodd, R.; Chadwick, D.; Hill, P.; Robinson, D.; Jones, D.

    2016-12-01

    Grasslands occupy more than 70% of the world's agricultural land and are major providers of healthy feed for livestock and for ecosystem services. Global warming is projected to increase the intensity and frequency of extreme weather events such as drought and flooding and will reduce persistency of currently productive but stress sensitive forage grass varieties, thereby challenging global food security and compromising on their existing ecosystem functionality. New perennial grass varieties, tolerant to the onsets of more than one abiotic stresses, are required in order to achieve sustainable grassland production and function over years under adverse environmental conditions. Identifying and selecting reliable morphological and physiological traits associated with increased resistance to multiple stress conditions is a prerequisite to ensure future grasslands resilience. The objectives of our study were to select from diverse and novel Festulolium (ryegrass spp. x fescue spp. hybrids) grass populations capable of providing optimal combinations of good forage production together with resilience to multiple stresses and to monitor morphological and physiological responses under multiple stress conditions. The grasses were: Festulolium variety Prior (L. perenne x F. pratensis), shown to alter soil structure and hydrology to mitigate run-off and flooding; two advanced breeding populations of diploid L. perenne with genes for drought tolerance derived from the Mediterranean fescue species F. arundinacea and F. glaucescens; two tetraploid hybrid populations involving L. perenne in combination with F. glaucescens and F. mairei (from North Africa), respectively. As controls, Festulolium variety AberNiche and L. perenne variety AberWolf varieties, were used. Treatments consisted of: A) Control; plants maintained at optimum conditions, B) Flood; plants were flooded for 6 weeks followed by a 4-week recovery, C) Drought; plants received limited quantity of water for 12 weeks

  6. Climate network analysis of regional precipitation extremes: The true story told by event synchronization

    Science.gov (United States)

    Odenweller, Adrian; Donner, Reik V.

    2017-04-01

    Over the last decade, complex network methods have been frequently used for characterizing spatio-temporal patterns of climate variability from a complex systems perspective, yielding new insights into time-dependent teleconnectivity patterns and couplings between different components of the Earth climate. Among the foremost results reported, network analyses of the synchronicity of extreme events as captured by the so-called event synchronization have been proposed to be powerful tools for disentangling the spatio-temporal organization of particularly extreme rainfall events and anticipating the timing of monsoon onsets or extreme floodings. Rooted in the analysis of spike train synchrony analysis in the neurosciences, event synchronization has the great advantage of automatically classifying pairs of events arising at two distinct spatial locations as temporally close (and, thus, possibly statistically - or even dynamically - interrelated) or not without the necessity of selecting an additional parameter in terms of a maximally tolerable delay between these events. This consideration is conceptually justified in case of the original application to spike trains in electroencephalogram (EEG) recordings, where the inter-spike intervals show relatively narrow distributions at high temporal sampling rates. However, in case of climate studies, precipitation extremes defined by daily precipitation sums exceeding a certain empirical percentile of their local distribution exhibit a distinctively different type of distribution of waiting times between subsequent events. This raises conceptual concerns if event synchronization is still appropriate for detecting interlinkages between spatially distributed precipitation extremes. In order to study this problem in more detail, we employ event synchronization together with an alternative similarity measure for event sequences, event coincidence rates, which requires a manual setting of the tolerable maximum delay between two

  7. Semi-supervised tracking of extreme weather events in global spatio-temporal climate datasets

    Science.gov (United States)

    Kim, S. K.; Prabhat, M.; Williams, D. N.

    2017-12-01

    Deep neural networks have been successfully applied to solve problem to detect extreme weather events in large scale climate datasets and attend superior performance that overshadows all previous hand-crafted methods. Recent work has shown that multichannel spatiotemporal encoder-decoder CNN architecture is able to localize events in semi-supervised bounding box. Motivated by this work, we propose new learning metric based on Variational Auto-Encoders (VAE) and Long-Short-Term-Memory (LSTM) to track extreme weather events in spatio-temporal dataset. We consider spatio-temporal object tracking problems as learning probabilistic distribution of continuous latent features of auto-encoder using stochastic variational inference. For this, we assume that our datasets are i.i.d and latent features is able to be modeled by Gaussian distribution. In proposed metric, we first train VAE to generate approximate posterior given multichannel climate input with an extreme climate event at fixed time. Then, we predict bounding box, location and class of extreme climate events using convolutional layers given input concatenating three features including embedding, sampled mean and standard deviation. Lastly, we train LSTM with concatenated input to learn timely information of dataset by recurrently feeding output back to next time-step's input of VAE. Our contribution is two-fold. First, we show the first semi-supervised end-to-end architecture based on VAE to track extreme weather events which can apply to massive scaled unlabeled climate datasets. Second, the information of timely movement of events is considered for bounding box prediction using LSTM which can improve accuracy of localization. To our knowledge, this technique has not been explored neither in climate community or in Machine Learning community.

  8. A hybrid hydrologically complemented warning model for shallow landslides induced by extreme rainfall in Korean Mountain

    Science.gov (United States)

    Singh Pradhan, Ananta Man; Kang, Hyo-Sub; Kim, Yun-Tae

    2016-04-01

    This study uses a physically based approach to evaluate the factor of safety of the hillslope for different hydrological conditions, in Mt Umyeon, south of Seoul. The hydrological conditions were determined using intensity and duration of whole Korea of known landslide inventory data. Quantile regression statistical method was used to ascertain different probability warning levels on the basis of rainfall thresholds. Physically based models are easily interpreted and have high predictive capabilities but rely on spatially explicit and accurate parameterization, which is commonly not possible. Statistical probabilistic methods can include other causative factors which influence the slope stability such as forest, soil and geology, but rely on good landslide inventories of the site. In this study a hybrid approach has described that combines the physically-based landslide susceptibility for different hydrological conditions. A presence-only based maximum entropy model was used to hybrid and analyze relation of landslide with conditioning factors. About 80% of the landslides were listed among the unstable sites identified in the proposed model, thereby presenting its effectiveness and accuracy in determining unstable areas and areas that require evacuation. These cumulative rainfall thresholds provide a valuable reference to guide disaster prevention authorities in the issuance of warning levels with the ability to reduce losses and save lives.

  9. Towards a unified study of extreme events using universality concepts and transdisciplinary analysis methods

    Science.gov (United States)

    Balasis, George; Donner, Reik V.; Donges, Jonathan F.; Radebach, Alexander; Eftaxias, Konstantinos; Kurths, Jürgen

    2013-04-01

    The dynamics of many complex systems is characterized by the same universal principles. In particular, systems which are otherwise quite different in nature show striking similarities in their behavior near tipping points (bifurcations, phase transitions, sudden regime shifts) and associated extreme events. Such critical phenomena are frequently found in diverse fields such as climate, seismology, or financial markets. Notably, the observed similarities include a high degree of organization, persistent behavior, and accelerated energy release, which are common to (among others) phenomena related to geomagnetic variability of the terrestrial magnetosphere (intense magnetic storms), seismic activity (electromagnetic emissions prior to earthquakes), solar-terrestrial physics (solar flares), neurophysiology (epileptic seizures), and socioeconomic systems (stock market crashes). It is an open question whether the spatial and temporal complexity associated with extreme events arises from the system's structural organization (geometry) or from the chaotic behavior inherent to the nonlinear equations governing the dynamics of these phenomena. On the one hand, the presence of scaling laws associated with earthquakes and geomagnetic disturbances suggests understanding these events as generalized phase transitions similar to nucleation and critical phenomena in thermal and magnetic systems. On the other hand, because of the structural organization of the systems (e.g., as complex networks) the associated spatial geometry and/or topology of interactions plays a fundamental role in the emergence of extreme events. Here, a few aspects of the interplay between geometry and dynamics (critical phase transitions) that could result in the emergence of extreme events, which is an open problem, will be discussed.

  10. 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. © 2015 APJPH.

  11. Vulnerability and resilience of the carbon exchange o a subarctic peatland to an extreme winter event

    DEFF Research Database (Denmark)

    Parmentier, Frans-Jan W.; Rasse, Daniel P.; Lund, Magnus

    2018-01-01

    impact of this event. Our results indicate that gross primary production (GPP) exhibited a delayed response to temperature following snowmelt. From snowmelt up to the peak of summer, this reduced carbon uptake by 14 (0-24) g Cm-2 (similar to 12% of GPP in that period)-similar to the effect of interannual......Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning-a reversal of the greening trend of the region-and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO2 uptake due to winter damage, however, remains...... event. The warm summer also increased ecosystem respiration, which limited net carbon uptake. This study shows that damage from a single extreme winter event can have an ecosystem-wide impact on CO2 uptake, and highlights the importance of including winter-induced shrub damage in terrestrial ecosystem...

  12. Experimental characterization of extreme events of inertial dissipation in a turbulent swirling flow

    Science.gov (United States)

    Saw, E. -W.; Kuzzay, D.; Faranda, D.; Guittonneau, A.; Daviaud, F.; Wiertel-Gasquet, C.; Padilla, V.; Dubrulle, B.

    2016-01-01

    The three-dimensional incompressible Navier–Stokes equations, which describe the motion of many fluids, are the cornerstones of many physical and engineering sciences. However, it is still unclear whether they are mathematically well posed, that is, whether their solutions remain regular over time or develop singularities. Even though it was shown that singularities, if exist, could only be rare events, they may induce additional energy dissipation by inertial means. Here, using measurements at the dissipative scale of an axisymmetric turbulent flow, we report estimates of such inertial energy dissipation and identify local events of extreme values. We characterize the topology of these extreme events and identify several main types. Most of them appear as fronts separating regions of distinct velocities, whereas events corresponding to focusing spirals, jets and cusps are also found. Our results highlight the non-triviality of turbulent flows at sub-Kolmogorov scales as possible footprints of singularities of the Navier–Stokes equation. PMID:27578459

  13. Potential compensation of hydrological extremes in headwaters: case study of upper Vltava River basin, Šumava Mts., Czechia

    Science.gov (United States)

    Kocum, Jan; Janský, Bohumír.; Česák, Julius

    2010-05-01

    Increasing frequency of catastrophic flash floods and extreme droughts in recent years results in an urgent need of solving of flood protection questions and measures leading to discharge increase in dry periods. Flattening of discharge call for the use of untraditional practices as a suitable complement to classical engineering methods. These measures could be represented by gradual increase of river catchment retention capacity in headstream areas. Very favorable conditions for this research solution are concentrated to the upper part of Otava River basin (Vltava River left tributary, Šumava Mts., southwestern Czechia) representing the core zone of a number of extreme floods in Central Europe and the area with high peat land proportion. A number of automatic ultrasound and hydrostatic pressure water level gauges, climatic stations and precipitation gauges and utilization of modern equipment and methods were used in chosen experimental catchments to assess the landscape retention potential and to find out rainfall-runoff relations in this area. Successively, the detailed analysis of peat land hydrological function was carried out. The peat bogs influence on runoff conditions were assessed by thorough comparison of runoff regimes in subcatchments with different peat land proportion. The peat bog influence on hydrological process can be considered also with respect to its affecting of water quality. Therefore, hydrological monitoring was completed by ion, carbon (TOC) and oxygen isotopes balance observing within periods of high or low discharges in order to precise runoff phases separation by means of anion deficiency. Pedological survey of different soil types and textures was carried out to precise the estimation of its water capacity. Detailed analyses of extreme runoff ascending and descending phases and minimum discharges in profiles closing several subcatchments with different physical-geographic conditions show higher peak flow frequency and their shorter

  14. Empirical assessment of effects of urbanization on event flow hydrology in watersheds of Canada's Great Lakes-St Lawrence basin

    Science.gov (United States)

    Trudeau, M. P.; Richardson, Murray

    2016-10-01

    We conducted an empirical hydrological analysis of high-temporal resolution streamflow records for 27 watersheds within 11 river systems in the Greater Toronto Region of the Canadian Great Lakes basin. Our objectives were to model the event-scale flow response of watersheds to urbanization and to test for scale and threshold effects. Watershed areas ranged from 37.5 km2 to 806 km2 and urban percent land cover ranged from less than 0.1-87.6%. Flow records had a resolution of 15-min increments and were available over a 42-year period, allowing for detailed assessment of changes in event-scale flow response with increasing urban land use during the post-freshet period (May 26 to November 15). Empirical statistical models were developed for flow characteristics including total runoff, runoff coefficient, eightieth and ninety-fifth percentile rising limb event runoff and mean rising limb event acceleration. Changes in some of these runoff metrics began at very low urban land use (acceleration increased with increasing urban cover, thus causing 80th percentile runoff depths to be reached sooner. These results indicate the potential for compromised water balance when cumulative changes are considered at the watershed scale. No abrupt or threshold changes in hydrologic characteristics were identified along the urban land use gradient. A positive interaction of urban percent land use and watershed size indicated a scale effect on total runoff. Overall, the results document compromised hydrologic stability attributable to urbanization during a period with no detectable change in rainfall patterns. They also corroborate literature recommendations for spatially distributed low impact urban development techniques; measures would be needed throughout the urbanized area of a watershed to dampen event-scale hydrologic responses to urbanization. Additional research is warranted into event-scale hydrologic trends with urbanization in other regions, in particular rising limb event

  15. 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...

  16. Extreme temperature events on Greenland in observations and the MAR regional climate model

    Science.gov (United States)

    Leeson, Amber A.; Eastoe, Emma; Fettweis, Xavier

    2018-03-01

    Meltwater from the Greenland Ice Sheet contributed 1.7-6.12 mm to global sea level between 1993 and 2010 and is expected to contribute 20-110 mm to future sea level rise by 2100. These estimates were produced by regional climate models (RCMs) which are known to be robust at the ice sheet scale but occasionally miss regional- and local-scale climate variability (e.g. Leeson et al., 2017; Medley et al., 2013). To date, the fidelity of these models in the context of short-period variability in time (i.e. intra-seasonal) has not been fully assessed, for example their ability to simulate extreme temperature events. We use an event identification algorithm commonly used in extreme value analysis, together with observations from the Greenland Climate Network (GC-Net), to assess the ability of the MAR (Modèle Atmosphérique Régional) RCM to reproduce observed extreme positive-temperature events at 14 sites around Greenland. We find that MAR is able to accurately simulate the frequency and duration of these events but underestimates their magnitude by more than half a degree Celsius/kelvin, although this bias is much smaller than that exhibited by coarse-scale Era-Interim reanalysis data. As a result, melt energy in MAR output is underestimated by between 16 and 41 % depending on global forcing applied. Further work is needed to precisely determine the drivers of extreme temperature events, and why the model underperforms in this area, but our findings suggest that biases are passed into MAR from boundary forcing data. This is important because these forcings are common between RCMs and their range of predictions of past and future ice sheet melting. We propose that examining extreme events should become a routine part of global and regional climate model evaluation and that addressing shortcomings in this area should be a priority for model development.

  17. Data-assisted reduced-order modeling of extreme events in complex dynamical systems.

    Directory of Open Access Journals (Sweden)

    Zhong Yi Wan

    Full Text Available The prediction of extreme events, from avalanches and droughts to tsunamis and epidemics, depends on the formulation and analysis of relevant, complex dynamical systems. Such dynamical systems are characterized by high intrinsic dimensionality with extreme events having the form of rare transitions that are several standard deviations away from the mean. Such systems are not amenable to classical order-reduction methods through projection of the governing equations due to the large intrinsic dimensionality of the underlying attractor as well as the complexity of the transient events. Alternatively, data-driven techniques aim to quantify the dynamics of specific, critical modes by utilizing data-streams and by expanding the dimensionality of the reduced-order model using delayed coordinates. In turn, these methods have major limitations in regions of the phase space with sparse data, which is the case for extreme events. In this work, we develop a novel hybrid framework that complements an imperfect reduced order model, with data-streams that are integrated though a recurrent neural network (RNN architecture. The reduced order model has the form of projected equations into a low-dimensional subspace that still contains important dynamical information about the system and it is expanded by a long short-term memory (LSTM regularization. The LSTM-RNN is trained by analyzing the mismatch between the imperfect model and the data-streams, projected to the reduced-order space. The data-driven model assists the imperfect model in regions where data is available, while for locations where data is sparse the imperfect model still provides a baseline for the prediction of the system state. We assess the developed framework on two challenging prototype systems exhibiting extreme events. We show that the blended approach has improved performance compared with methods that use either data streams or the imperfect model alone. Notably the improvement is more

  18. Data-assisted reduced-order modeling of extreme events in complex dynamical systems.

    Science.gov (United States)

    Wan, Zhong Yi; Vlachas, Pantelis; Koumoutsakos, Petros; Sapsis, Themistoklis

    2018-01-01

    The prediction of extreme events, from avalanches and droughts to tsunamis and epidemics, depends on the formulation and analysis of relevant, complex dynamical systems. Such dynamical systems are characterized by high intrinsic dimensionality with extreme events having the form of rare transitions that are several standard deviations away from the mean. Such systems are not amenable to classical order-reduction methods through projection of the governing equations due to the large intrinsic dimensionality of the underlying attractor as well as the complexity of the transient events. Alternatively, data-driven techniques aim to quantify the dynamics of specific, critical modes by utilizing data-streams and by expanding the dimensionality of the reduced-order model using delayed coordinates. In turn, these methods have major limitations in regions of the phase space with sparse data, which is the case for extreme events. In this work, we develop a novel hybrid framework that complements an imperfect reduced order model, with data-streams that are integrated though a recurrent neural network (RNN) architecture. The reduced order model has the form of projected equations into a low-dimensional subspace that still contains important dynamical information about the system and it is expanded by a long short-term memory (LSTM) regularization. The LSTM-RNN is trained by analyzing the mismatch between the imperfect model and the data-streams, projected to the reduced-order space. The data-driven model assists the imperfect model in regions where data is available, while for locations where data is sparse the imperfect model still provides a baseline for the prediction of the system state. We assess the developed framework on two challenging prototype systems exhibiting extreme events. We show that the blended approach has improved performance compared with methods that use either data streams or the imperfect model alone. Notably the improvement is more significant in

  19. 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.

  20. Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland.

    Science.gov (United States)

    Baynes, Edwin R C; Attal, Mikaël; Niedermann, Samuel; Kirstein, Linda A; Dugmore, Andrew J; Naylor, Mark

    2015-02-24

    Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (>10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

  1. Proactive modeling of water quality impacts of extreme precipitation events in a drinking water reservoir.

    Science.gov (United States)

    Jeznach, Lillian C; Hagemann, Mark; Park, Mi-Hyun; Tobiason, John E

    2017-10-01

    Extreme precipitation events are of concern to managers of drinking water sources because these occurrences can affect both water supply quantity and quality. However, little is known about how these low probability events impact organic matter and nutrient loads to surface water sources and how these loads may impact raw water quality. This study describes a method for evaluating the sensitivity of a water body of interest from watershed input simulations under extreme precipitation events. An example application of the method is illustrated using the Wachusett Reservoir, an oligo-mesotrophic surface water reservoir in central Massachusetts and a major drinking water supply to metropolitan Boston. Extreme precipitation event simulations during the spring and summer resulted in total organic carbon, UV-254 (a surrogate measurement for reactive organic matter), and total algae concentrations at the drinking water intake that exceeded recorded maximums. Nutrient concentrations after storm events were less likely to exceed recorded historical maximums. For this particular reservoir, increasing inter-reservoir transfers of water with lower organic matter content after a large precipitation event has been shown in practice and in model simulations to decrease organic matter levels at the drinking water intake, therefore decreasing treatment associated oxidant demand, energy for UV disinfection, and the potential for formation of disinfection byproducts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Cyclones and extreme windstorm events over Europe under climate change: Global and regional climate model diagnostics

    Science.gov (United States)

    Leckebusch, G. C.; Ulbrich, U.

    2003-04-01

    More than any changes of the climate system mean state conditions, the development of extreme events may influence social, economic and legal aspects of our society. This linkage results from the impact of extreme climate events (natural hazards) on environmental systems which again are directly linked to human activities. Prominent examples from the recent past are the record breaking rainfall amounts of August 2002 in central Europe which produced widespread floodings or the wind storm Lothar of December 1999. Within the MICE (Modelling the Impact of Climate Extremes) project framework an assessment of the impact of changes in extremes will be done. The investigation is carried out for several different impact categories as agriculture, energy use and property damage. Focus is laid on the diagnostics of GCM and RCM simulations under different climate change scenarios. In this study we concentrate on extreme windstorms and their relationship to cyclone activity in the global HADCM3 as well as in the regional HADRM3 model under two climate change scenarios (SRESA2a, B2a). In order to identify cyclones we used an objective algorithm from Murry and Simmonds which was widely tested under several different conditions. A slight increase in the occurrence of systems is identified above northern parts of central Europe for both scenarios. For more severe systems (core pressure Spain) a shift to more deep cyclones connected with an increasing number of strong wind events is found.

  3. Inter- and Intra- Field variations in soil compaction levels and subsequent impacts on hydrological extremes

    Science.gov (United States)

    Pattison, Ian; Coates, Victoria

    2015-04-01

    The rural landscape in the UK is dominated by pastoral agriculture, with about 40% of land cover classified as either improved or semi-natural grassland according to the Land Cover Map 2007. Intensification has resulted in greater levels of compaction associated with higher stocking densities. However, there is likely to be a great amount of variability in compaction levels within and between fields due to multiple controlling factors. This research focusses in on two of these factors; firstly animal species, namely sheep, cattle and horses; and secondly field zonation e.g. feeding areas, field gates, open field. Field experiments have been conducted in multiple fields in the River Skell catchment, in Yorkshire, UK, which has an area of 140km2. The effect on physical and hydrologic soil characteristics such as bulk density and moisture contents have been quantified using a wide range of field and laboratory based experiments. Results have highlighted statistically different properties between heavily compacted areas where animals congregate and less-trampled open areas. Furthermore, soil compaction has been hypothesised to contribute to increased flood risk at larger spatial scales. Previous research (Pattison, 2011) on a ~40km2 catchment (Dacre Beck, Lake District, UK) has shown that when soil characteristics are homogeneously parameterised in a hydrological model, downstream peak discharges can be 65% higher for a heavy compacted soil than for a lightly compacted soil. Here we report results from spatially distributed hydrological modelling using soil parameters gained from the field experimentation. Results highlight the importance of both the percentage of the catchment which is heavily compacted and also the spatial distribution of these fields.

  4. Exploring regional stakeholder needs and requirements in terms of Extreme Weather Event Attribution

    Science.gov (United States)

    Schwab, M.; Meinke, I.; Vanderlinden, J. P.; Touili, N.; Von Storch, H.

    2015-12-01

    Extreme event attribution has increasingly received attention in the scientific community. It may also serve decision-making at the regional level where much of the climate change impact mitigation takes place. Nevertheless, there is, to date, little known about the requirements of regional actors in terms of extreme event attribution. We have therefore analysed these at the example of regional decision-makers for climate change-related activities and/or concerned with storm surge risks at the German Baltic Sea and heat wave risks in the Greater Paris area. In order to explore if stakeholders find scientific knowledge from extreme event attribution useful and how this information might be relevant to their decision-making, we consulted a diverse set of actors engaged in the assessment, mitigation and communication of storm surge, heat wave, and climate change-related risks. Extreme event attribution knowledge was perceived to be most useful to public and political awareness-raising, but was of little or no relevance for the consulted stakeholders themselves. It was not acknowledged that it would support adaptation planning as sometimes argued in the literature. The consulted coastal protection, health, and urban adaptation planners rather needed reliable statements about possible future changes in extreme events than causal statements about past events. To enhance salience, a suitable product of event attribution should be linked to regional problems, vulnerabilities, and impacts of climate change. Given that the tolerance of uncertainty is rather low, most of the stakeholders also claimed that a suitable product of event attribution is to be received from a trusted "honest broker" and published rather later, but with smaller uncertainties than vice versa. Institutional mechanisms, like regional climate services, which enable and foster communication, translation and mediation across the boundaries between knowledge and action can help fulfill such requirements

  5. 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...

  6. 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

    of extreme rainfall events, a statistical model is tested for this purpose. The model is built on the theory of generalized linear models and uses Poisson regression solved by generalized estimation equations. Spatial and temporal explanatory variables can be included simultaneously, and their relative...

  7. Prevention through policy : Urban macroplastic leakages to the marine environment during extreme rainfall events

    NARCIS (Netherlands)

    Axelsson, Charles; van Sebille, Erik

    2017-01-01

    The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic

  8. Community Response and Engagement During Extreme Water Events in Saskatchewan, Canada and Queensland, Australia

    Science.gov (United States)

    McMartin, Dena W.; Sammel, Alison J.; Arbuthnott, Katherine

    2018-01-01

    Technology alone cannot address the challenges of how societies, communities, and individuals understand water accessibility, water management, and water consumption, particularly under extreme conditions like floods and droughts. At the community level, people are increasingly aware challenges related to responses to and impacts of extreme water events. This research begins with an assessment of social and political capacities of communities in two Commonwealth jurisdictions, Queensland, Australia and Saskatchewan, Canada, in response to major flooding events. The research further reviews how such capacities impact community engagement to address and mitigate risks associated with extreme water events and provides evidence of key gaps in skills, understanding, and agency for addressing impacts at the community level. Secondary data were collected using template analysis to elucidate challenges associated with education (formal and informal), social and political capacity, community ability to respond appropriately, and formal government responses to extreme water events in these two jurisdictions. The results indicate that enhanced community engagement alongside elements of an empowerment model can provide avenues for identifying and addressing community vulnerability to negative impacts of flood and drought.

  9. Controlling spatio-temporal extreme events by decreasing the localized energy

    International Nuclear Information System (INIS)

    Du Lin; Xu Wei; Li Zhanguo; Zhou Bingchang

    2011-01-01

    The problem of controlling extreme events in spatially extended dynamical systems is investigated in this Letter. Based on observations of the system state, the control technique we proposed locally decreases the spatial energy of the amplitude in the vicinity of the highest burst, without needs of any knowledge or prediction of the system model. Considering the specific Complex Ginzburg-Landau equation, we provide theoretical analysis for designing the localized state feedback controller. More exactly, a simple control law by varying a damping parameter at control region is chose to achieve the control. Numerical simulations and statistic analysis demonstrate that extreme events can be efficiently suppressed by our strategy. In particular, the cost of the control and the tolerant time delay in applying the control is considered in detail. - Highlights: → We propose a local control scheme to suppress spatio-temporal extreme events. → The control is address by decreasing the spatial energy of the system locally. → The detail control law is to apply localized state feedback based on observations. → The cost of the control increases with the size of the control region exponentially. → The tolerant delay of the control is about 5-6 times of lifetime of extreme events.

  10. Behavioural, ecological and evolutionary responses to extreme climatic events : Challenges and directions

    NARCIS (Netherlands)

    Van de Pol, Martijn; Jenouvrier, Stéphanie; Cornelissen, Johannes H.C.; Visser, Marcel E.

    2017-01-01

    More extreme climatic events (ECEs) are among the most prominent consequences of climate change. Despite a long-standing recognition of the importance of ECEs by paleo-ecologists and macro-evolutionary biologists, ECEs have only recently received a strong interest in the wider ecological and

  11. Artistic Creativity and Extreme Events: The Heterogeneous Impact of War on Composers’ Production

    DEFF Research Database (Denmark)

    Borowiecki, Karol Jan

    2014-01-01

    The relationship between extreme events and creativity is rather ambiguous and yet of significance across several disciplines. The following study adds to the debate by analyzing the impact of war on individual artistic output by building on a global sample of 115 prominent composers born after...

  12. Hazard analysis of typhoon-related external events using extreme value theory

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yo Chan; Jang, Seung Cheol [Integrated Safety Assessment Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lim, Tae Jin [Dept. of Industrial Information Systems Engineering, Soongsil University, Seoul (Korea, Republic of)

    2015-02-15

    After the Fukushima accident, the importance of hazard analysis for extreme external events was raised. To analyze typhoon-induced hazards, which are one of the significant disasters of East Asian countries, a statistical analysis using the extreme value theory, which is a method for estimating the annual exceedance frequency of a rare event, was conducted for an estimation of the occurrence intervals or hazard levels. For the four meteorological variables, maximum wind speed, instantaneous wind speed, hourly precipitation, and daily precipitation, the parameters of the predictive extreme value theory models were estimated. The 100-year return levels for each variable were predicted using the developed models and compared with previously reported values. It was also found that there exist significant long-term climate changes of wind speed and precipitation. A fragility analysis should be conducted to ensure the safety levels of a nuclear power plant for high levels of wind speed and precipitation, which exceed the results of a previous analysis.

  13. Analysis of land cover change impact on flood events using remote sensing, GIS and hydrological models: a case study of the Nyando River Basin in Kenya

    International Nuclear Information System (INIS)

    Olang, L. O.

    2009-01-01

    In this study, land cover changes in the Nyando River basin (3500 km 2 ) of Kenya were analyzed and their impact of floods quantified. Three Landsat satellite images for 1973, 1986 and 2000 were acquired, processed and classified based on seven major land cover classes prevalent in the basin using a hybrid of supervised and non supervised classification procedures. The detected land cover changes, together with a DEM and a soil map of the basin, were then used to estimate physically based parameters for the selected hydrological models. The models were then used to estimate local and flood peak discharges and volumes arising from selected storm events for each state of the classified land cover dataset. To further understand how changes in the land cover may impact on the flood hydrology, three scenarios that represent quite extreme alternatives were formulated to study the possible bandwidth during floods. Land cover classification results revealed immense land degradation over the span of study. Forests reduced by an area of 488 km 2 representing a 20% decline, while agricultural fields expanded by 581 km 2 representing a 16% increase over the same period of time (1973-2000). Hydrological modeling results indicated that the basin underwent significant increase in the peak discharge value. The flood peak discharges in the whole basin were noted to have increased by at least 16% over the period of 1973 -2000.Flood volumes were also noted to have increased by at least 10% over the same period of time. (author) [de

  14. Response of conservation measures from small cultivated watersheds, concerning runoff and erosion, under the impact of extreme rainfall events

    International Nuclear Information System (INIS)

    Popa, N

    2008-01-01

    The study has been made in a representative small watershed with gently to hilly slopes from Tutova Rolling Hills, Romania. The system of conservation measures is represented by stripcroping, bufferstrips, bench terraces, a grassed waterway and a drainage network. The monitoring of hydrological response of agricultural units has been made in two cross sections corresponding to each of the land use type by means of two concrete triangular weirs. The most important soil losses were caused by three extreme rainfall events from August 2004, May 2005 and September 2007. At the date of the first rainfall event, the soil was generally very well protected against erosion by the vegetative cover, excepting parcels that were just ploughed after the mash crop. In that case, it was estimated that the value of soil losses ranged between 20.0 and 24.5 t/ha while for the other crops like corn and soybean, soil losses they were 1.0-1.5 t/ha and 0.5-0.8 t/ha respectively. Damages caused by the rainfall from September 2007 were much more important because at that time about 30% from the entire surface was just prepared for rape seeding. Maximum value of erosion was 95 t/ha on a parcel with 16% slope and 50m length along the slope.

  15. Response of conservation measures from small cultivated watersheds, concerning runoff and erosion, under the impact of extreme rainfall events

    Science.gov (United States)

    Popa, N.

    2008-11-01

    The study has been made in a representative small watershed with gently to hilly slopes from Tutova Rolling Hills, Romania. The system of conservation measures is represented by stripcroping, bufferstrips, bench terraces, a grassed waterway and a drainage network. The monitoring of hydrological response of agricultural units has been made in two cross sections corresponding to each of the land use type by means of two concrete triangular weirs. The most important soil losses were caused by three extreme rainfall events from August 2004, May 2005 and September 2007. At the date of the first rainfall event, the soil was generally very well protected against erosion by the vegetative cover, excepting parcels that were just ploughed after the mash crop. In that case, it was estimated that the value of soil losses ranged between 20.0 and 24.5 t/ha while for the other crops like corn and soybean, soil losses they were 1.0-1.5 t/ha and 0.5-0.8 t/ha respectively. Damages caused by the rainfall from September 2007 were much more important because at that time about 30% from the entire surface was just prepared for rape seeding. Maximum value of erosion was 95 t/ha on a parcel with 16% slope and 50m length along the slope.

  16. Food Security and Extreme Events: Evidence from Smallholder Farmers in Central America

    Science.gov (United States)

    Saborio-Rodriguez, M.; Alpizar, F.; Harvey, C.; Martinez, R.; Vignola, R.; Viguera, B.; Capitan, T.

    2016-12-01

    Extreme weather events, which are expected to increase in magnitude and frequency due to climate change, are one of the main threats for smallholder farmers in Central America. Using a rich dataset from carefully selected subsistence farm households, we explore the determinants and severity of food insecurity resulting from extreme hydrometeorological hazards. In addition, we analyze farmerś coping strategies. Our analysis sheds light over food insecurity as an expression of vulnerability in a region that is expected to be increasingly exposed to extreme events and in a population already stressed by poverty and lack of opportunities. Regarding food insecurity, multivariate analyses indicate that education, having at least one migrant in the household, labor allocation, number of plots, and producing coffee are determinants of the probability of experiencing lack of food after an extreme weather event. Once the household is lacking food, the duration of the episode is related to access to credit, number of plots, producing coffee, ownership of land and gender of the head of the household. This results are in line with previous literature on the determinants of food insecurity in particular, and vulnerability, in general. Our dataset also allows us to analyze coping strategies. Households experiencing lack of food after an extreme weather event report mainly changes in their habits, as decreasing the amount of food consumed (54%) and modifying their diet (35%). A low proportion of household (between 10% and 15%, depending on the nature of the event) use their assets, by redirecting their savings, migrating, and selling items from the house. Asking money or food from family and friends or from an organization is reported for 4% of the households. This general results are connected to the specific coping strategies related to damages in crops, which are explored in detail. Our results indicate that there are patterns among the household experiencing lack of food

  17. Transformation of soil organics under extreme climate events: a project description

    Science.gov (United States)

    Blagodatskaya, Evgenia

    2017-04-01

    Recent climate scenarios predict not only continued global warming but also an increased frequency and intensity of extreme climatic events such as strong changes in temperature and precipitation with unusual regional dynamics. Weather anomalies at European territory of Russia are currently revealed as long-term drought and strong showers in summer and as an increased frequency of soil freezing-thawing cycles. Climate extremes totally change biogeochemical processes and elements cycling both at the ecosystem level and at the level of soil profile mainly affecting soil biota. Misbalance in these processes can cause a reduction of soil carbon stock and an increase of greenhouse gases emission. Our project aims to reveal the transformation mechanisms of soil organic matter caused by extreme weather events taking into consideration the role of biotic-abiotic interactions in regulation of formation, maintenance and turnover of soil carbon stock. Our research strategy is based on the novel concept considering extreme climatic events (showers after long-term droughts, soil flooding, freezing-thawing) as abiotic factors initiating a microbial succession. Study on stoichiometric flexibility of plants under climate extremes as well as on resulting response of soil heterotrophs on stoichiometric changes in substrate will be used for experimental prove and further development of the theory of ecological stoichiometry. The results enable us to reveal the mechanisms of biotic - abiotic interactions responsible for the balance between mobilization and stabilization of soil organic matter. Identified mechanisms will form the basis of an ecosystem model enabled to predict the effects of extreme climatic events on biogenic carbon cycle in the biosphere.

  18. Revisiting the 1993 historical extreme precipitation and damaging flood event in Central Nepal

    Science.gov (United States)

    Marahatta, S.; Adhikari, L.; Pokharel, B.

    2017-12-01

    Nepal is ranked the fourth most climate-vulnerable country in the world and it is prone to different weather-related hazards including droughts, floods, and landslides [Wang et al., 2013; Gillies et al., 2013]. Although extremely vulnerable to extreme weather events, there are no extreme weather warning system established to inform public in Nepal. Nepal has witnessed frequent drought and flood events, however, the extreme precipitation that occurred on 19-20 July 1993 created a devastating flood and landslide making it the worst weather disaster in the history of Nepal. During the second week of July, Nepal and northern India experienced abnormal dry condition due to the shifting of the monsoon trough to central India. The dry weather changed to wet when monsoon trough moved northward towards foothills of the Himalayas. Around the same period, a low pressure center was located over the south-central Nepal. The surface low was supported by the mid-, upper-level shortwave and cyclonic vorticity. A meso-scale convective system created record breaking one day rainfall (540 mm) in the region. The torrential rain impacted the major hydropower reservoir, Bagmati barrage in Karmaiya and triggered many landslides and flash floods. The region had the largest hydropower (Kulekhani hydropower, 92 MW) of the country at that time and the storm event deposited extremely large amount of sediments that reduced one-fourth (4.8 million m3) of reservoir dead storage (12 million m3). The 1-in-1000 years flood damaged the newly constructed barrage and took more than 700 lives. Major highways were damaged cutting off supply of daily needed goods, including food and gas, in the capital city, Kathmandu, for more than a month. In this presentation, the meteorological conditions of the extreme event will be diagnosed and the impact of the sedimentation due to the flood on Kulekhani reservoir and hydropower generation will be discussed.

  19. Modeling extreme "Carrington-type" space weather events using three-dimensional global MHD simulations

    Science.gov (United States)

    Ngwira, Chigomezyo M.; Pulkkinen, Antti; Kuznetsova, Maria M.; Glocer, Alex

    2014-06-01

    There is a growing concern over possible severe societal consequences related to adverse space weather impacts on man-made technological infrastructure. In the last two decades, significant progress has been made toward the first-principles modeling of space weather events, and three-dimensional (3-D) global magnetohydrodynamics (MHD) models have been at the forefront of this transition, thereby playing a critical role in advancing our understanding of space weather. However, the modeling of extreme space weather events is still a major challenge even for the modern global MHD models. In this study, we introduce a specially adapted University of Michigan 3-D global MHD model for simulating extreme space weather events with a Dst footprint comparable to the Carrington superstorm of September 1859 based on the estimate by Tsurutani et. al. (2003). Results are presented for a simulation run with "very extreme" constructed/idealized solar wind boundary conditions driving the magnetosphere. In particular, we describe the reaction of the magnetosphere-ionosphere system and the associated induced geoelectric field on the ground to such extreme driving conditions. The model setup is further tested using input data for an observed space weather event of Halloween storm October 2003 to verify the MHD model consistence and to draw additional guidance for future work. This extreme space weather MHD model setup is designed specifically for practical application to the modeling of extreme geomagnetically induced electric fields, which can drive large currents in ground-based conductor systems such as power transmission grids. Therefore, our ultimate goal is to explore the level of geoelectric fields that can be induced from an assumed storm of the reported magnitude, i.e., Dst˜=-1600 nT.

  20. Vulnerability assessment of Central-East Sardinia (Italy to extreme rainfall events

    Directory of Open Access Journals (Sweden)

    A. Bodini

    2010-01-01

    Full Text Available In Sardinia (Italy, the highest frequency of extreme events is recorded in the Central-East area (3–4 events per year. The presence of high and steep mountains near the sea on the central and south-eastern coast, causes an East-West precipitation gradient in autumn especially, due to hot and moist currents coming from Africa. Soil structure and utilization make this area highly vulnerable to flash flooding and landslides. The specific purpose of this work is to provide a description of the heavy rainfall phenomenon on a statistical basis. The analysis mainly focuses on i the existence of trends in heavy rainfall and ii the characterization of the distribution of extreme events. First, to study possible trends in extreme events a few indices have been analyzed by the linear regression test. The analysis has been carried out at annual and seasonal scales. Then, extreme values analysis has been carried out by fitting a Generalized Pareto Distribution (GPD to the data. As far as trends are concerned, different results are obtained at the two temporal scales: significant trends are obtained at the seasonal scale which are masked at the annual scale. By combining trend analysis and GPD analysis, the vulnerability of the study area to the occurrence of heavy rainfall has been characterized. Therefore, this work might support the improvement of land use planning and the application of suitable prevention systems. Future work will consider the extension of the analysis to all Sardinia and the application of statistical methods taking into account the spatial correlation of extreme events.

  1. Quantification of climate change effects on extreme precipitation used for high resolution hydrologic design

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, Karsten

    2012-01-01

    are studied, all based on output from historical rain series of the present climate and output from Regional Climate Models. Two models are applied, one being based on an extreme value model, the Partial Duration Series Approach, and the other based on a stochastic rainfall generator model. Finally...

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

    International Nuclear Information System (INIS)

    Hansen, Brage B; Isaksen, Ketil; Benestad, Rasmus E; Kohler, Jack; Pedersen, Åshild Ø; Loe, Leif E; Coulson, Stephen J; Larsen, Jan Otto; Varpe, Øystein

    2014-01-01

    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)

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

    Science.gov (United States)

    Hansen, Brage B.; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif E.; Coulson, Stephen J.; Larsen, Jan Otto; Varpe, Øystein

    2014-11-01

    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.

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

    International Nuclear Information System (INIS)

    Pfister, A.; Goossen, C.; Coogler, K.; Gorgemans, J.

    2012-01-01

    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 AP1000 R 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

  5. AP1000{sup R} design robustness against extreme external events - Seismic, flooding, and aircraft crash

    Energy Technology Data Exchange (ETDEWEB)

    Pfister, A.; Goossen, C.; Coogler, K.; Gorgemans, J. [Westinghouse Electric Company LLC, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

    2012-07-01

    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 AP1000{sup R} 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

  6. THE 2012 JULY 23 BACKSIDE ERUPTION: AN EXTREME ENERGETIC PARTICLE EVENT?

    Energy Technology Data Exchange (ETDEWEB)

    Gopalswamy, N. [Code 671, Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Yashiro, S.; Thakur, N.; Mäkelä, P.; Xie, H.; Akiyama, S., E-mail: nat.gopalswamy@nasa.gov [Department of Physics, The Catholic University of America, Washington, DC 20064 (United States)

    2016-12-20

    The backside coronal mass ejection (CME) of 2012 July 23 had a short Sun-to-Earth shock transit time (18.5 hr). The associated solar energetic particle (SEP) event had a >10 MeV proton flux peaking at ∼5000 pfu, and the energetic storm particle event was an order of magnitude larger, making it the most intense event in the space era at these energies. By a detailed analysis of the CME, shock, and SEP characteristics, we find that the July 23 event is consistent with a high-energy SEP event (accelerating particles to gigaelectronvolt energies). The times of maximum and fluence spectra in the range 10–100 MeV were very hard, similar to those of ground-level enhancement (GLE) events. We found a hierarchical relationship between the CME initial speeds and the fluence spectral indices: CMEs with low initial speeds had SEP events with the softest spectra, while those with the highest initial speeds had SEP events with the hardest spectra. CMEs attaining intermediate speeds result in moderately hard spectra. The July 23 event was in the group of hard-spectrum events. During the July 23 event, the shock speed (>2000 km s{sup −1}), the initial acceleration (∼1.70 km s{sup −2}), and the shock-formation height (∼1.5 solar radii) were all typical of GLE events. The associated type II burst had emission components from meter to kilometer wavelengths, suggesting a strong shock. These observations confirm that the 2012 July 23 event is likely to be an extreme event in terms of the energetic particles it accelerated.

  7. Antarctic Climate Change: Extreme Events Disrupt Plastic Phenotypic Response in Adélie Penguins

    Science.gov (United States)

    Lescroël, Amélie; Ballard, Grant; Grémillet, David; Authier, Matthieu; Ainley, David G.

    2014-01-01

    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. PMID:24489657

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

    International Nuclear Information System (INIS)

    Choi, In-Kil; Hahm, Daegi; Kim, Min Kyu

    2014-01-01

    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)

  9. Antarctic climate change: extreme events disrupt plastic phenotypic response in Adélie 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.

  10. 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.

  11. Mathematical aspects of assessing extreme events for the safety of nuclear plants

    Science.gov (United States)

    Potempski, Slawomir; Borysiewicz, Mieczyslaw

    2015-04-01

    In the paper the review of mathematical methodologies applied for assessing low frequencies of rare natural events like earthquakes, tsunamis, hurricanes or tornadoes, floods (in particular flash floods and surge storms), lightning, solar flares, etc., will be given in the perspective of the safety assessment of nuclear plants. The statistical methods are usually based on the extreme value theory, which deals with the analysis of extreme deviation from the median (or the mean). In this respect application of various mathematical tools can be useful, like: the extreme value theorem of Fisher-Tippett-Gnedenko leading to possible choices of general extreme value distributions, or the Pickands-Balkema-de Haan theorem for tail fitting, or the methods related to large deviation theory. In the paper the most important stochastic distributions relevant for performing rare events statistical analysis will be presented. This concerns, for example, the analysis of the data with the annual extreme values (maxima - "Annual Maxima Series" or minima), or the peak values, exceeding given thresholds at some periods of interest ("Peak Over Threshold"), or the estimation of the size of exceedance. Despite of the fact that there is a lack of sufficient statistical data directly containing rare events, in some cases it is still possible to extract useful information from existing larger data sets. As an example one can consider some data sets available from the web sites for floods, earthquakes or generally natural hazards. Some aspects of such data sets will be also presented taking into account their usefulness for the practical assessment of risk for nuclear power plants coming from extreme weather conditions.

  12. A systemic approach for managing extreme risk events-dynamic financial analysis

    Directory of Open Access Journals (Sweden)

    Ph.D.Student Rodica Ianole

    2011-12-01

    Full Text Available 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 framework of extreme risk events.

  13. Identifying Population Vulnerable to Extreme Heat Events in San Jose, California.

    Science.gov (United States)

    Rivera, A. L.

    2016-12-01

    The extreme heat days not only make cities less comfortable for living but also they are associated with increased morbidity and mortality. Mapping studies have demonstrated spatial variability in heat vulnerability. A study conducted between 2000 and 2011 in New York City shows that deaths during heat waves was more likely to occur in black individuals, at home in census tracts which received greater public assistance. This map project intends to portray areas in San Jose California that are vulnerable to extreme heat events. The variables considered to build a vulnerability index are: land surface temperature, vegetated areas (NDVI), and people exposed to these area (population density).

  14. Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

    Science.gov (United States)

    Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

    2010-10-01

    Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

  15. Projections of extreme water level events for atolls in the western Tropical Pacific

    Science.gov (United States)

    Merrifield, M. A.; Becker, J. M.; Ford, M.; Yao, Y.

    2014-12-01

    Conditions that lead to extreme water levels and coastal flooding are examined for atolls in the Republic of the Marshall Islands based on a recent field study of wave transformations over fringing reefs, tide gauge observations, and wave model hindcasts. Wave-driven water level extremes pose the largest threat to atoll shorelines, with coastal levels scaling as approximately one-third of the incident breaking wave height. The wave-driven coastal water level is partitioned into a mean setup, low frequency oscillations associated with cross-reef quasi-standing modes, and wind waves that reach the shore after undergoing high dissipation due to breaking and bottom friction. All three components depend on the water level over the reef; however, the sum of the components is independent of water level due to cancelling effects. Wave hindcasts suggest that wave-driven water level extremes capable of coastal flooding are infrequent events that require a peak wave event to coincide with mid- to high-tide conditions. Interannual and decadal variations in sea level do not change the frequency of these events appreciably. Future sea-level rise scenarios significantly increase the flooding threat associated with wave events, with a nearly exponential increase in flooding days per year as sea level exceeds 0.3 to 1.0 m above current levels.

  16. Environmental prediction, risk assessment and extreme events: adaptation strategies for the developing world

    Science.gov (United States)

    Webster, Peter J.; Jian, Jun

    2011-01-01

    The uncertainty associated with predicting extreme weather events has serious implications for the developing world, owing to the greater societal vulnerability to such events. Continual exposure to unanticipated extreme events is a contributing factor for the descent into perpetual and structural rural poverty. We provide two examples of how probabilistic environmental prediction of extreme weather events can support dynamic adaptation. In the current climate era, we describe how short-term flood forecasts have been developed and implemented in Bangladesh. Forecasts of impending floods with horizons of 10 days are used to change agricultural practices and planning, store food and household items and evacuate those in peril. For the first time in Bangladesh, floods were anticipated in 2007 and 2008, with broad actions taking place in advance of the floods, grossing agricultural and household savings measured in units of annual income. We argue that probabilistic environmental forecasts disseminated to an informed user community can reduce poverty caused by exposure to unanticipated extreme events. Second, it is also realized that not all decisions in the future can be made at the village level and that grand plans for water resource management require extensive planning and funding. Based on imperfect models and scenarios of economic and population growth, we further suggest that flood frequency and intensity will increase in the Ganges, Brahmaputra and Yangtze catchments as greenhouse-gas concentrations increase. However, irrespective of the climate-change scenario chosen, the availability of fresh water in the latter half of the twenty-first century seems to be dominated by population increases that far outweigh climate-change effects. Paradoxically, fresh water availability may become more critical if there is no climate change. PMID:22042897

  17. Hydro-meteorological extreme events in the 18th century in Portugal

    Science.gov (United States)

    Fragoso, Marcelo; João Alcoforado, Maria; Taborda, João Paulo

    2013-04-01

    The present work is carried out in the frame of the KLIMHIST PROJECT ("Reconstruction and model simulations of past climate in Portugal using documentary and early instrumental sources, 17th-19th century)", and is devoted to the study of hydro-meteorological extreme events during the last 350 years, in order to understand how they have changed in time and compare them with current analogues. More specifically, the results selected to this presentation will focus on some hydro-meteorological extreme events of the 18th century, like severe droughts, heavy precipitation episodes and windstorms. One of the most noteworthy events was the winterstorm Bárbara (3rd to 6th December 1739), already studied in prior investigations (Taborda et al, 2004; Pfister et al, 2010), a devastating storm with strong impacts in Portugal caused by violent winds and heavy rainfall. Several other extreme events were detected by searching different documentary archives, including individual, administrative and ecclesiastic sources. Moreover, a more detailed insight to the 1783-1787 period will be made with regard the Lisbon region, taking into consideration the availability of information for daily meteorological observations as well as documentary evidences, like descriptions from Gazeta de Lisboa, the periodic with more continuous publication in the 18thcentury. Key-words: Instrumental data, Documentary data, Extreme events, Klimhist Project, Portugal References Pfister, C., Garnier, E., Alcoforado, M.J., Wheeler, D. Luterbacher, J. Nunes, M.F., Taborda, J.P. (2010) The meteorological framework and the cultural memory of three severe winter-storms in early eighteenth-century Europe, Climatic Change, 101, 1-2, 281-310 Taborda, JP; Alcoforado, MJ and Garcia, JC (2004) O Clima do Sul de Portugal no Séc.XVIII, Centro de Estudos Geográficos, Área de de Investigação de Geo-Ecologia, relatório no 2

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

    Science.gov (United States)

    Mahmud, A.; Hixson, M.; Kleeman, M. J.

    2012-08-01

    The effect of climate change on population-weighted concentrations of particulate matter (PM) during extreme pollution 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. The current study found that the change in annual-average population-weighted PM2.5 mass concentrations due to climate change between 2000 vs. 2050 within any major sub-region in California was not statistically significant. However, 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-yr period in the SJV increased by 21% due to enhanced production of secondary particulate matter (manifested as NH4NO3). In general, climate change caused increased stagnation during future extreme pollution events, leading to higher exposure to diesel engines

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

    Directory of Open Access Journals (Sweden)

    A. Mahmud

    2012-08-01

    Full Text Available The effect of climate change on population-weighted concentrations of particulate matter (PM during extreme pollution 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.

    The current study found that the change in annual-average population-weighted PM2.5 mass concentrations due to climate change between 2000 vs. 2050 within any major sub-region in California was not statistically significant. However, 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-yr period in the SJV increased by 21% due to enhanced production of secondary particulate matter (manifested as NH4NO3. In general, climate

  20. Spatial and temporal analysis of extreme sea level and storm surge events around the coastline of the UK.

    Science.gov (United States)

    Haigh, Ivan D; Wadey, Matthew P; Wahl, Thomas; Ozsoy, Ozgun; Nicholls, Robert J; Brown, Jennifer M; Horsburgh, Kevin; Gouldby, Ben

    2016-12-06

    In this paper we analyse the spatial footprint and temporal clustering of extreme sea level and skew surge events around the UK coast over the last 100 years (1915-2014). The vast majority of the extreme sea level events are generated by moderate, rather than extreme skew surges, combined with spring astronomical high tides. We distinguish four broad categories of spatial footprints of events and the distinct storm tracks that generated them. There have been rare events when extreme levels have occurred along two unconnected coastal regions during the same storm. The events that occur in closest succession (sea level events from happening within 4-8 days. Finally, the 2013/14 season was highly unusual in the context of the last 100 years from an extreme sea level perspective.

  1. 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

    procedures are subsequently applied to flood records from 48 catchments in New Zealand. To identify homogeneous groupings of catchments, a split-sample regionalization approach based on catchment characteristics is adopted. The defined groups are more homogeneous for PDS data than for AMS data; a two...

  2. Adaption to Extreme Rainfall with Open Urban Drainage System: An Integrated Hydrological Cost-Benefit Analysis

    DEFF Research Database (Denmark)

    Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark

    2013-01-01

    with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas....... The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental...

  3. Do climate extreme events foster violent civil conflicts? A coincidence analysis

    Science.gov (United States)

    Schleussner, Carl-Friedrich; Donges, Jonathan F.; Donner, Reik V.

    2014-05-01

    Civil conflicts promoted by adverse environmental conditions represent one of the most important potential feedbacks in the global socio-environmental nexus. While the role of climate extremes as a triggering factor is often discussed, no consensus is yet reached about the cause-and-effect relation in the observed data record. Here we present results of a rigorous statistical coincidence analysis based on the Munich Re Inc. extreme events database and the Uppsala conflict data program. We report evidence for statistically significant synchronicity between climate extremes with high economic impact and violent conflicts for various regions, although no coherent global signal emerges from our analysis. Our results indicate the importance of regional vulnerability and might aid to identify hot-spot regions for potential climate-triggered violent social conflicts.

  4. Committed Vulnerability to Extreme Weather Events in the United States (Invited)

    Science.gov (United States)

    Preston, B. L.

    2013-12-01

    Despite improvements in disaster risk management in the United States, a trend toward increasing economic losses from extreme weather events has been observed. This trend has been attributed to growth in socioeconomic exposure to extremes driven by the concentration of population and wealth on hazardous landscapes. As geographic patterns of demography and economic development are associated with strong path dependence, the United States is ';locked-in' to future increases in exposure and associated economic losses in the decades ahead, irrespective of the influence of climate change. To understand the influence of path dependence on past and future losses, an index of potential socioeconomic exposure was developed at the U.S. county level based upon population size and inflation-adjusted wealth proxies. Since 1960, exposure has increased preferentially in the U.S. Southeast, particularly coastal and urban counties and Southwest relative to the Great Plains and Northeast. Projected changes in exposure from 2009 to 2054 based upon scenarios of future demographic and economic change suggest a long-term commitment to increasing, but spatially heterogeneous, exposure to extremes, independent of climate change. The implications of this path dependence are examined in the context of several natural hazards. Annualized county-level losses from 1960-2008 for five climate-related natural hazards were normalized to 2009 values and then scaled based upon projected changes in exposure and two different estimates of the exposure elasticity of losses. Results indicate that losses from extreme events will grow by a factor of 1.3-1.7 and 1.8-3.9 by 2025 and 2050, respectively, with the exposure elasticity representing a major source of uncertainty. At more local scales, however, such as rapidly growing metropolitan areas, losses are anticipated to grow more rapidly. As such, improving understanding of the societal implications of the extreme weather events of the future

  5. Developing research about extreme events and impacts to support international climate policy

    Science.gov (United States)

    Otto, Friederike; James, Rachel; Parker, Hannah; Boyd, Emily; Jones, Richard; Allen, Myles; Mitchell, Daniel; Cornforth, Rosalind

    2015-04-01

    Climate change is expected to have some of its most significant impacts through changes in the frequency and severity of extreme events. There is a pressing need for policy to support adaptation to changing climate risks, and to deal with residual loss and damage from climate change. In 2013, the Warsaw International Mechanism was established by the United Nations Framework Convention on Climate Change (UNFCCC) to address loss and damage in developing countries. Strategies to help vulnerable regions cope with losses from extreme events will presumably require information about the influence of anthropogenic forcing on extreme weather. But what kind of scientific evidence will be most useful for the Warsaw Mechanism? And how can the scientific communities working on extreme events and impacts develop their research to support the advance of this important policy? As climate scientists conducting probabilistic event attribution studies, we have been working with social scientists to investigate these questions. Our own research seeks to examine the role of external drivers, including greenhouse gas emissions, on the risk of extreme weather events such as heatwaves, flooding, and drought. We use large ensembles of climate models to compute the probability of occurrence of extreme events under current conditions and in a world which might have been without anthropogenic interference. In cases where the models are able to simulate extreme weather, the analysis allows for conclusions about the extent to which climate change may have increased, decreased, or made no change to the risk of the event occurring. These results could thus have relevance for the UNFCCC negotiations on loss and damage, and we have been communicating with policymakers and observers to the policy process to better understand how we can develop our research to support their work; by attending policy meetings, conducting interviews, and using a participatory game developed with the Red Cross

  6. Complex active regions as the main source of extreme and large solar proton events

    Science.gov (United States)

    Ishkov, V. N.

    2013-12-01

    A study of solar proton sources indicated that solar flare events responsible for ≥2000 pfu proton fluxes mostly occur in complex active regions (CARs), i.e., in transition structures between active regions and activity complexes. Different classes of similar structures and their relation to solar proton events (SPEs) and evolution, depending on the origination conditions, are considered. Arguments in favor of the fact that sunspot groups with extreme dimensions are CARs are presented. An analysis of the flare activity in a CAR resulted in the detection of "physical" boundaries, which separate magnetic structures of the same polarity and are responsible for the independent development of each structure.

  7. 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

  8. 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.

  9. Attribution of Extreme Rainfall Events in the South of France Using EURO-CORDEX Simulations

    Science.gov (United States)

    Luu, L. N.; Vautard, R.; Yiou, P.

    2017-12-01

    The Mediterranean region regularly undergoes episodes of intense precipitation in the fall season that exceed 300mm a day. This study focuses on the role of climate change on the dynamics of the events that occur in the South of France. We used an ensemble of 10 EURO-CORDEX model simulations with two horizontal resolutions (EUR-11: 0.11° and EUR-44: 0.44°) for the attribution of extreme rainfall in the fall in the Cevennes mountain range (South of France). The biases of the simulations were corrected with simple scaling adjustment and a quantile correction (CDFt). This produces five datasets including EUR-44 and EUR-11 with and without scaling adjustment and CDFt-EUR-11, on which we test the impact of resolution and bias correction on the extremes. Those datasets, after pooling all of models together, are fitted by a stationary Generalized Extreme Value distribution for several periods to estimate a climate change signal in the tail of distribution of extreme rainfall in the Cévenne region. Those changes are then interpreted by a scaling model that links extreme rainfall with mean and maximum daily temperature. The results show that higher-resolution simulations with bias adjustment provide a robust and confident increase of intensity and likelihood of occurrence of autumn extreme rainfall in the area in current climate in comparison with historical climate. The probability (exceedance probability) of 1-in-1000-year event in historical climate may increase by a factor of 1.8 under current climate with a confident interval of 0.4 to 5.3 following the CDFt bias-adjusted EUR-11. The change of magnitude appears to follow the Clausius-Clapeyron relation that indicates a 7% increase in rainfall per 1oC increase in temperature.

  10. The role of the subtropical North Atlantic water cycle in recent US extreme precipitation events

    Science.gov (United States)

    Li, Laifang; Schmitt, Raymond W.; Ummenhofer, Caroline C.

    2018-02-01

    The role of the oceanic water cycle in the record-breaking 2015 warm-season precipitation in the US is analyzed. The extreme precipitation started in the Southern US in the spring and propagated northward to the Midwest and the Great Lakes in the summer of 2015. This seasonal evolution of precipitation anomalies represents a typical mode of variability of US warm-season precipitation. Analysis of the atmospheric moisture flux suggests that such a rainfall mode is associated with moisture export from the subtropical North Atlantic. In the spring, excessive precipitation in the Southern US is attributable to increased moisture flux from the northwestern portion of the subtropical North Atlantic. The North Atlantic moisture flux interacts with local soil moisture which enables the US Midwest to draw more moisture from the Gulf of Mexico in the summer. Further analysis shows that the relationship between the rainfall mode and the North Atlantic water cycle has become more significant in recent decades, indicating an increased likelihood of extremes like the 2015 case. Indeed, two record-high warm-season precipitation events, the 1993 and 2008 cases, both occurred in the more recent decades of the 66 year analysis period. The export of water from the North Atlantic leaves a marked surface salinity signature. The salinity signature appeared in the spring preceding all three extreme precipitation events analyzed in this study, i.e. a saltier-than-normal subtropical North Atlantic in spring followed by extreme Midwest precipitation in summer. Compared to the various sea surface temperature anomaly patterns among the 1993, 2008, and 2015 cases, the spatial distribution of salinity anomalies was much more consistent during these extreme flood years. Thus, our study suggests that preseason salinity patterns can be used for improved seasonal prediction of extreme precipitation in the Midwest.

  11. Adaption to extreme rainfall with open urban drainage system: an integrated hydrological cost-benefit analysis.

    Science.gov (United States)

    Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark; Arnbjerg-Nielsen, Karsten

    2013-03-01

    This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken.

  12. Modelling of extreme rainfall events in Peninsular Malaysia based on annual maximum and partial duration series

    Science.gov (United States)

    Zin, Wan Zawiah Wan; Shinyie, Wendy Ling; Jemain, Abdul Aziz

    2015-02-01

    In this study, two series of data for extreme rainfall events are generated based on Annual Maximum and Partial Duration Methods, derived from 102 rain-gauge stations in Peninsular from 1982-2012. To determine the optimal threshold for each station, several requirements must be satisfied and Adapted Hill estimator is employed for this purpose. A semi-parametric bootstrap is then used to estimate the mean square error (MSE) of the estimator at each threshold and the optimal threshold is selected based on the smallest MSE. The mean annual frequency is also checked to ensure that it lies in the range of one to five and the resulting data is also de-clustered to ensure independence. The two data series are then fitted to Generalized Extreme Value and Generalized Pareto distributions for annual maximum and partial duration series, respectively. The parameter estimation methods used are the Maximum Likelihood and the L-moment methods. Two goodness of fit tests are then used to evaluate the best-fitted distribution. The results showed that the Partial Duration series with Generalized Pareto distribution and Maximum Likelihood parameter estimation provides the best representation for extreme rainfall events in Peninsular Malaysia for majority of the stations studied. Based on these findings, several return values are also derived and spatial mapping are constructed to identify the distribution characteristic of extreme rainfall in Peninsular Malaysia.

  13. OCCURRENCE OF EXTREME SOLAR PARTICLE EVENTS: ASSESSMENT FROM HISTORICAL PROXY DATA

    International Nuclear Information System (INIS)

    Usoskin, Ilya G.; Kovaltsov, Gennady A.

    2012-01-01

    The probability of occurrence of extreme solar particle events (SPEs) with proton fluence (>30 MeV) F 30 ≥ 10 10 cm –2 is evaluated based on data on the cosmogenic isotopes 14 C and 10 Be in terrestrial archives covering centennial-millennial timescales. Four potential candidates with F 30 = (1-1.5) × 10 10 cm –2 and no events with F 30 > 2 × 10 10 cm –2 are identified since 1400 AD in the annually resolved 10 Be data. A strong SPE related to the Carrington flare of 1859 AD is not supported by the data. For the last 11,400 years, 19 SPE candidates with F 30 = (1-3) × 10 10 cm –2 are found and clearly no event with F 30 > 5 × 10 10 cm –2 (50 times the SPE of 1956 February 23) has occurred. These values serve as observational upper limits on the strength of SPEs on the timescale of tens of millennia. Two events, ca. 780 and 1460 AD, appear in different data series making them strong candidates for extreme SPEs. We build a distribution of the occurrence probability of extreme SPEs, providing a new strict observational constraint. Practical limits can be set as F 30 ≈ 1, 2-3, and 5×10 10 cm –2 for occurrence probabilities ≈10 –2 , 10 –3 , and 10 –4 yr –1 , respectively. Because of the uncertainties, our results should be interpreted as a conservative upper limit on the SPE occurrence near Earth. The mean solar energetic particle (SEP) flux is evaluated as ≈40 (cm 2 s) –1 , in agreement with estimates from lunar rocks. On average, extreme SPEs contribute about 10% to the total SEP fluence.

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

    OpenAIRE

    A. Mahmud; M. Hixson; M. J. Kleeman

    2012-01-01

    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 ...

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

    OpenAIRE

    A. Mahmud; M. Hixson; M. J. Kleeman

    2012-01-01

    The effect of climate change on population-weighted concentrations of particulate matter (PM) during extreme pollution 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 ...

  16. Agent Based Simulation of Group Emotions Evolution and Strategy Intervention in Extreme Events

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available Agent based simulation method has become a prominent approach in computational modeling and analysis of public emergency management in social science research. The group emotions evolution, information diffusion, and collective behavior selection make extreme incidents studies a complex system problem, which requires new methods for incidents management and strategy evaluation. This paper studies the group emotion evolution and intervention strategy effectiveness using agent based simulation method. By employing a computational experimentation methodology, we construct the group emotion evolution as a complex system and test the effects of three strategies. In addition, the events-chain model is proposed to model the accumulation influence of the temporal successive events. Each strategy is examined through three simulation experiments, including two make-up scenarios and a real case study. We show how various strategies could impact the group emotion evolution in terms of the complex emergence and emotion accumulation influence in extreme events. This paper also provides an effective method of how to use agent-based simulation for the study of complex collective behavior evolution problem in extreme incidents, emergency, and security study domains.

  17. 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.

  18. 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.

  19. Psychological and Physical Impacts of Extreme Events on Older Adults: Implications for Communications.

    Science.gov (United States)

    McClelland, Erin; Amlôt, Richard; Rogers, M Brooke; Rubin, G James; Tesh, John; Pearce, Julia M

    2017-02-01

    In recent years, a series of large-scale, high-profile natural disasters and terrorist attacks have demonstrated the need for thorough and effective disaster preparedness. While these extreme events affect communities and societies as a whole, they also carry specific risks for particular population groups. Crises such as Hurricane Katrina and the 2011 earthquake and tsunami disaster in Japan have illustrated the risk of significant and disproportionate morbidity and mortality among older adults during disasters. Age does not necessarily equate to vulnerability, but many physical and psychological consequences of the aging process can increase the risk of adverse outcomes. As the older population grows, so too does the need to ensure that adequate, practical, and appropriate measures exist to offset the specific risks from extreme events associated with this subpopulation. Effective risk and crisis communication plays a key role in mitigating the extent to which older adults are differentially affected during extreme events. By identifying the specific issues affecting older adults, this review highlights important areas for action for practitioners and policy-makers, particularly in the realm of crisis communication. (Disaster Med Public Health Preparedness. 2017;11:127-134).

  20. Are extreme hydro-meteorological events a prerequisite for extreme water quality impacts? Exploring climate impacts on inland and coastal waters

    Science.gov (United States)

    Michalak, A. M.; Balaji, V.; Del Giudice, D.; Sinha, E.; Zhou, Y.; Ho, J. C.

    2017-12-01

    Questions surrounding water sustainability, climate change, and extreme events are often framed around water quantity - whether too much or too little. The massive impacts of extreme water quality impairments are equally compelling, however. Recent years have provided a host of compelling examples, with unprecedented harmful algal blooms developing along the West coast, in Utah Lake, in Lake Erie, and off the Florida coast, and huge hypoxic dead zones continuing to form in regions such as Lake Erie, the Chesapeake Bay, and the Gulf of Mexico. Linkages between climate change, extreme events, and water quality impacts are not well understood, however. Several factors explain this lack of understanding, including the relative complexity of underlying processes, the spatial and temporal scale mismatch between hydrologists and climatologists, and observational uncertainty leading to ambiguities in the historical record. Here, we draw on a number of recent studies that aim to quantitatively link meteorological variability and water quality impacts to test the hypothesis that extreme water quality impairments are the result of extreme hydro-meteorological events. We find that extreme hydro-meteorological events are neither always a necessary nor a sufficient condition for the occurrence of extreme water quality impacts. Rather, extreme water quality impairments often occur in situations where multiple contributing factors compound, which complicates both attribution of historical events and the ability to predict the future incidence of such events. Given the critical societal importance of water quality projections, a concerted program of uncertainty reduction encompassing observational and modeling components will be needed to examine situations where extreme weather plays an important, but not solitary, role in the chain of cause and effect.

  1. Evidence of Teleconnections between the Peruvian central Andes and Northeast Brazil during extreme rainfall events

    Science.gov (United States)

    Sulca, J. C.; Vuille, M. F.; Silva, F. Y.; Takahashi, K.

    2013-12-01

    Knowledge about changes in regional circulation and physical processes associated with extreme rainfall events in South America is limited. Here we investigate such events over the Mantaro basin (MB) located at (10°S-13°S; 73°W-76°W) in the central Peruvian Andes and Northeastern Brazil (NEB), located at (9°S-15°S; 39°W-46°W). Occasional dry and wet spells can be observed in both areas during the austral summer season. The main goal of this study is to investigate potential teleconnections between extreme rainfall events in MB and NEB during austral summer. We define wet (dry) spells as periods that last for at least 3 (5) consecutive days with rainfall above (below) the 70 (30) percentile. To identify the dates of ocurrence of these events, we used daily accumulated rainfall data from 14 climate stations located in the Mantaro basin for the period 1965 to 2002. In NEB we defined a rainfall index which is based on average daily gridded rainfall data within the region for the same period. Dry (wet spells) in the MB are associated with positive (negative) OLR anomalies which extend over much of the tropical Andes, indicating the large-scale nature of these events. At 200 hPa anomalous easterly (westerly) zonal winds aloft accompany wet (dry) spells. Composite anomalies of dry spells in MB reveal significant contemporaneous precipitation anomalies of the opposite sign over NEB, which suggest that intraseasonal precipitation variability over the two regions may be dynamically linked. Indeed upper-tropospheric circulation anomalies over the central Andes extend across South America and appear to be tied to an adjustment in the Bolivian High-Nordeste Low system. Dry (wet) spells in NEB are equally associated with a large-scale pattern of positive (negative) OLR anomalies; however, there are no related significant OLR anomalies over the MB during these events. Dry (wet) spells are associated with robust patterns of anomalous wind fields at both low and upper

  2. Extreme events in total ozone: Spatio-temporal analysis from local to global scale

    Science.gov (United States)

    Rieder, Harald E.; Staehelin, Johannes; Maeder, Jörg A.; Ribatet, Mathieu; di Rocco, Stefania; Jancso, Leonhardt M.; Peter, Thomas; Davison, Anthony C.

    2010-05-01

    Recently tools from extreme value theory (e.g. Coles, 2001; Ribatet, 2007) have been applied for the first time in the field of stratospheric ozone research, as statistical analysis showed that previously used concepts assuming a Gaussian distribution (e.g. fixed deviations from mean values) of total ozone data do not address the internal data structure concerning extremes adequately (Rieder et al., 2010a,b). A case study the world's longest total ozone record (Arosa, Switzerland - for details see Staehelin et al., 1998a,b) illustrates that tools based on extreme value theory are appropriate to identify ozone extremes and to describe the tails of the total ozone record. Excursions in the frequency of extreme events reveal "fingerprints" of dynamical factors such as ENSO or NAO, and chemical factors, such as cold Arctic vortex ozone losses, as well as major volcanic eruptions of the 20th century (e.g. Gunung Agung, El Chichón, Mt. Pinatubo). Furthermore, atmospheric loading in ozone depleting substances led to a continuous modification of column ozone in the northern hemisphere also with respect to extreme values (partly again in connection with polar vortex contributions). It is shown that application of extreme value theory allows the identification of many more such fingerprints than conventional time series analysis of annual and seasonal mean values. Especially, the extremal analysis shows the strong influence of dynamics, revealing that even moderate ENSO and NAO events have a discernible effect on total ozone (Rieder et al., 2010b). Overall the extremes concept provides new information on time series properties, variability, trends and the influence of dynamics and chemistry, complementing earlier analyses focusing only on monthly (or annual) mean values. Findings described above could be proven also for the total ozone records of 5 other long-term series (Belsk, Hohenpeissenberg, Hradec Kralove, Potsdam, Uccle) showing that strong influence of atmospheric

  3. Identifying evidence of climate change impact on extreme events in permeable chalk catchments

    Science.gov (United States)

    Butler, A. P.; Nubert, S.

    2009-12-01

    The permeable chalk catchments of southern England are vital for the economy and well being of the UK. Not only important as a water resource, their freely draining soils support intensive agricultural production, and the rolling downs and chalk streams provide important habitants for many protected plant and animal species. Consequently, there are concerns about the potential impact of climate change on such catchments, particularly in relation to groundwater recharge. Of major concern are possible changes in extreme events, such as groundwater floods and droughts, as any increase in the frequency and/or severity of these has important consequences for water resources, ecological systems and local infrastructure. Studies of climate change impact on extreme events for such catchments have indicated that, under medium and high emissions scenarios, droughts are likely to become more severe whilst floods less so. However, given the uncertainties in such predictions and the inherent variability in historic data, producing definitive evidence of changes in flood/drought frequency/severity poses a significant challenge. Thus, there is a need for specific extreme event statistics that can be used as indicators of actual climate change in streamflow and groundwater level observations. Identifying such indicators that are sufficiently robust requires catchments with long historic time series data. One such catchment is the River Lavant, an intermittent chalk stream in West Sussex, UK. Located within this catchment is Chilgrove House, the site of the UK’s longest groundwater monitoring well (with a continuous record of water level observations of varying frequency dating back to 1836). Using a variety of meteorological datasets, the behaviour of the catchment has been modelled, from 1855 to present, using a 'leaky aquifer' conceptual model. Model calibration was based on observed daily streamflow, at a gauging station just outside the town of Chichester, from 1970. Long

  4. Methods and Model Dependency of Extreme Event Attribution: The 2015 European Drought

    Science.gov (United States)

    Hauser, Mathias; Gudmundsson, Lukas; Orth, René; Jézéquel, Aglaé; Haustein, Karsten; Vautard, Robert; van Oldenborgh, Geert J.; Wilcox, Laura; Seneviratne, Sonia I.

    2017-10-01

    Science on the role of anthropogenic influence on extreme weather events, such as heatwaves or droughts, has evolved rapidly in the past years. The approach of "event attribution" compares the occurrence-probability of an event in the present, factual climate with its probability in a hypothetical, counterfactual climate without human-induced climate change. Several methods can be used for event attribution, based on climate model simulations and observations, and usually researchers only assess a subset of methods and data sources. Here, we explore the role of methodological choices for the attribution of the 2015 meteorological summer drought in Europe. We present contradicting conclusions on the relevance of human influence as a function of the chosen data source and event attribution methodology. Assessments using the maximum number of models and counterfactual climates with pre-industrial greenhouse gas concentrations point to an enhanced drought risk in Europe. However, other evaluations show contradictory evidence. These results highlight the need for a multi-model and multi-method framework in event attribution research, especially for events with a low signal-to-noise ratio and high model dependency such as regional droughts.

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

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Sonal, E-mail: S.Choudhary@sheffield.ac.uk [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Management School, University of Sheffield, Conduit Road, Sheffield S10 1FL (United Kingdom); Blaud, Aimeric [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Osborn, A. Mark [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); School of Applied Sciences, RMIT University, PO Box 71, Bundoora, VIC 3083 (Australia); Press, Malcolm C. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Manchester Metropolitan University, Manchester, M15 6BH (United Kingdom); Phoenix, Gareth K. [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom)

    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 {sup 15}N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g N m{sup −2} yr{sup −1}, applied as {sup 15}NH{sub 4}{sup 15}NO{sub 3} in Svalbard (79{sup °}N), during the summer. Separate applications of {sup 15}NO{sub 3}{sup −} and {sup 15}NH{sub 4}{sup +} were also made to determine the importance of N form in their retention. More than 95% of the total {sup 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 {sup 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 {sup 15}NO{sub 3}{sup −} than {sup 15}NH{sub 4}{sup +}, 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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 "1"5N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g N m"−"2 yr"−"1, applied as "1"5NH_4"1"5NO_3 in Svalbard (79"°N), during the summer. Separate applications of "1"5NO_3"− and "1"5NH_4"+ were also made to determine the importance of N form in their retention. More than 95% of the total "1"5N 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 "1"5N 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 "1"5NO_3"− than "1"5NH_4"+, 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. - Highlights: • High Arctic tundra demonstrated a

  7. Vegetation Cover and Furrow Erosion due to Extreme Rain Events in Semiarid Environments

    Directory of Open Access Journals (Sweden)

    Belén Cárceles-Rodríguez

    2017-05-01

    Full Text Available The conservation of the soil resource in semi-arid environments is one of the major challenges of agricultural systems, particularly in the Mediterranean region. In the present study, two types of soil management were compared: minimum tillage (ML and minimum tillage with spontaneous vegetation cover (MLVE. The comparison was conducted in a rainfed almond plantation at slope (35%, under an extraordinary event in 2015 (91.3 mm and EI30 of 2,719.89 mm ha-1 h-1. In this situation in MLVE plots, the development of furrows in contrast to ML were not recorded; the total soil loss was more than 12 times lower than that recorded in the latter. This fact demonstrated the effectiveness of the vegetal cover in the protection of the agricultural soil against the erosion during extreme events. Also, for ML management, furrow erosion represented more than 60% of the total soil loss, demonstrating the dominance of this type of erosion. Finally, it should be noted that this event represents the almost total loss of soil recorded in the experimental plots during the period 2012-2015; and this consequently shows the significant impact of extreme events on erosion rates in the Mediterranean region.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  9. Investigating extreme event loading on coastal bridges using wireless sensor technology

    Science.gov (United States)

    Gelineau, Douglas A.; Davis, Justin R.; Rice, Jennifer A.

    2017-04-01

    Coastal infrastructure, such as bridges, are susceptible to many forms of coastal hazards: particularly hurricane surge and wave loading. These two forms of loading can cause catastrophic damage to aging highway infrastructure. It is estimated that storm damage costs the United States about $50 Billion per year. In light of this, it is crucial that we understand the damaging forces placed on infrastructure during storm events so that we can develop safer and more resilient coastal structures. This paper presents the ongoing research to enable the efficient collection of extreme event loads acting on both the substructure and superstructure of low clearance, simple span, reinforced concrete bridges. Bridges of this type were commonly constructed during the 1950's and 60's and are particularly susceptible to deck unseating caused by hurricane surge and wave loading. The sensing technology used to capture this data must be ruggedized to survive in an extremely challenging environment, be designed to allow for redundancy in the event of sensors or other network components being lost in the storm, and be relatively low cost to allow for more bridges to be instrumented per storm event. The prototype system described in this paper includes wireless technology, rapid data transmission, and, for the sensors, self-contained power. While this specific application focuses on hurricane hazards, the framework can be extended to include other natural hazards.

  10. Extreme weather events in developing countries and related injuries and mental health disorders - a systematic review

    Directory of Open Access Journals (Sweden)

    Elisabeth Rataj

    2016-09-01

    Full Text Available Abstract Background Due to climate change, extreme weather events have an incremental impact on human health. Injuries and mental health disorders are a particular burden of disease, which is broadly investigated in high income countries. Most distressed populations are, however, those in developing countries. Therefore, this study investigates mental and physical health impacts arising from extreme weather events in these populations. Method Post-traumatic Stress Disorder (PTSD, injury [primary outcomes], anxiety and depressive disorders [secondary outcomes], caused by weather extremes were systematically analyzed in people of developing countries. A systematic review of observational studies was conducted searching six databases, complemented by hand search, and utilizing two search engines. Review processing was done independently by two reviewers. Prevalence rates were analyzed in a pre/post design; an additional semi-structured search was conducted, to provide reference data for studies not incorporating reference values. Results All 17 identified studies (70,842 individuals indicate a disease increase, compared to the reference data. Increase ranges from 0.7–52.6 % for PTSD, and from 0.3–37.3 % for injury. No studies on droughts and heatwaves were identified. All studies were conducted in South America and Asia. Conclusion There is an increased burden of psychological diseases and injury. This finding needs to be incorporated into activities of prevention, preparedness and general health care of those developing countries increasingly experiencing extreme weather events. There is also a gap in research in Africa (in quantity and quality of studies in this field and a predominant heterogeneity of health assessment tools. PROSPERO registration no.: CRD42014009109

  11. A laboratory evaluation of the influence of weighing gauges performance on extreme events statistics

    Science.gov (United States)

    Colli, Matteo; Lanza, Luca

    2014-05-01

    The effects of inaccurate ground based rainfall measurements on the information derived from rain records is yet not much documented in the literature. La Barbera et al. (2002) investigated the propagation of the systematic mechanic errors of tipping bucket type rain gauges (TBR) into the most common statistics of rainfall extremes, e.g. in the assessment of the return period T (or the related non-exceedance probability) of short-duration/high intensity events. Colli et al. (2012) and Lanza et al. (2012) extended the analysis to a 22-years long precipitation data set obtained from a virtual weighing type gauge (WG). The artificial WG time series was obtained basing on real precipitation data measured at the meteo-station of the University of Genova and modelling the weighing gauge output as a linear dynamic system. This approximation was previously validated with dedicated laboratory experiments and is based on the evidence that the accuracy of WG measurements under real world/time varying rainfall conditions is mainly affected by the dynamic response of the gauge (as revealed during the last WMO Field Intercomparison of Rainfall Intensity Gauges). The investigation is now completed by analyzing actual measurements performed by two common weighing gauges, the OTT Pluvio2 load-cell gauge and the GEONOR T-200 vibrating-wire gauge, since both these instruments demonstrated very good performance under previous constant flow rate calibration efforts. A laboratory dynamic rainfall generation system has been arranged and validated in order to simulate a number of precipitation events with variable reference intensities. Such artificial events were generated basing on real world rainfall intensity (RI) records obtained from the meteo-station of the University of Genova so that the statistical structure of the time series is preserved. The influence of the WG RI measurements accuracy on the associated extreme events statistics is analyzed by comparing the original intensity

  12. Catalogue of extreme wave events in Ireland: revised and updated for 14 680 BP to 2017

    Science.gov (United States)

    O'Brien, Laura; Renzi, Emiliano; Dudley, John M.; Clancy, Colm; Dias, Frédéric

    2018-03-01

    This paper aims to extend and update the survey of extreme wave events in Ireland that was previously carried out by O'Brien et al. (2013). The original catalogue highlighted the frequency of such events dating back as far as the turn of the last ice age and as recent as 2012. Ireland's marine territory extends far beyond its coastline and is one of the largest seabed territories in Europe. It is therefore not surprising that extreme waves have continued to occur regularly since 2012, particularly considering the severity of weather during the winters of 2013-2014 and 2015-2016. In addition, a large number of storm surges have been identified since the publication of the original catalogue. This paper updates the O'Brien et al. (2013) catalogue to include events up to the end of 2017. Storm surges are included as a new category and events are categorised into long waves (tsunamis and storm surges) and short waves (storm and rogue waves). New results prior to 2012 are also included and some of the events previously documented are reclassified. Important questions regarding public safety, services and the influence of climate change are also highlighted. An interactive map has been created to allow the reader to navigate through events: https://drive.google.com/open?id=19cZ59pDHfDnXKYIziYAVWV6AfoE&usp=sharing" target="_blank">https://drive.google.com/open?id=19cZ59pDHfDnXKYIziYAVWV6AfoE&usp=sharing.

  13. 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.

  14. Mitigation Efforts in Rural Communities after Extreme Weather Events - New Insights for Stakeholders

    Directory of Open Access Journals (Sweden)

    Vesela Radovic

    2016-09-01

    Full Text Available Global climate changes are undoubtedly course of the increasing frequency of extreme whether events all over the world. Rural communities belong to the “group of victims” which is greatly jeopardized by consequences of the extreme weather events. Having in mind limited capacities for the preparedness, response and recovery after any kind of emergency it is clear that the rural community mostly needs external help. That is the point of this paper: to make new insights about this important issue, and to discuss: “how to provide adequate help in the rural communities and build adequate adaptive and response capacities”. In many countries agriculture and rural tourism are main economic activities in the rural area and its interruption could be the obstacle for implementation of sustainable development. Various stakeholders omit to be aware of this issue. Emergency agencies and many others have to make the comprehensive plan for rural communities (having in mind all its limitations. In the Republic of Serbia rural communities do not have enough capacity for recovery and usually it takes many years after an event. A minimum of an economic recovery standard has to be created for the rural community. It also has to be a specific contingency plan in the future reorganizations of emergency services in Serbia and at the Western Balkan region. It should be one of the priority issues for stakeholders in the near future in disaster risk reduction. Providing equal access to resources to population in the rural community after the extreme weather event has to be the priority task for policy makers and all actors in emergency management.

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

    International Nuclear Information System (INIS)

    Miroshnichenko, L.I.; Nymmik, R.A.

    2014-01-01

    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.

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

    International Nuclear Information System (INIS)

    John, Ranjeet; Chen Jiquan; Ouyang Zutao; Becker, Richard; Xiao Jingfeng; Samanta, Arindam; Ganguly, Sangram; Yuan Wenping; Batkhishig, Ochirbat

    2013-01-01

    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)

  17. The Chennai extreme rainfall event in 2015: The Bay of Bengal connection

    Science.gov (United States)

    Boyaj, Alugula; Ashok, Karumuri; Ghosh, Subimal; Devanand, Anjana; Dandu, Govardhan

    2018-04-01

    Southeast India experienced a heavy rainfall during 30 Nov-2 Dec 2015. Particularly, the Chennai city, the fourth major metropolitan city in India with a population of 5 million, experienced extreme flooding and causalities. Using various observed/reanalysed datasets, we find that the concurrent southern Bay of Bengal (BoB) sea surface temperatures (SST) were anomalously warm. Our analysis shows that BoB sea surface temperature anomalies (SSTA) are indeed positively, and significantly, correlated with the northeastern Indian monsoonal rainfall during this season. Our sensitivity experiments carried out with the Weather Research and Forecasting (WRF) model at 25 km resolution suggest that, while the strong concurrent El Niño conditions contributed to about 21.5% of the intensity of the extreme Chennai rainfall through its signals in the local SST mentioned above, the warming trend in BoB SST also contributed equally to the extremity of the event. Further, the El Niño southern oscillation (ENSO) impacts on the intensity of the synoptic events in the BoB during the northeast monsoon are manifested largely through the local SST in the BoB as compared through its signature in the atmospheric circulations over the BoB.

  18. The role of extreme drought events in modelling the distribution of beech at its xeric limit

    Science.gov (United States)

    Rasztovits, Ervin; Berki, Imre; Eredics, Attila; Móricz, Norbert

    2014-05-01

    Context: Projections of species distribution models (SDMs) for future climate conditions are based on long term mean climate data. For management and conservation issues SDMs have been extensively used, but it is not tested whether models that are successful in predicting current distributions are equally powerful in predicting distributions under future climates. Methods: Observations after 2003 confirms that extreme drought events played an important role in driving beech mortality at low-elevation xeric limits. The objective of this study was (1) to set up a simple extreme drought event based vitality model (EDM) using sanitary logging information as a proxy of vitality response of beech and (2) to compare the spatial pattern of the predicted vitality loss provided by the EDM with the distribution limits of the SDMs for three terms (2025, 2050 and 2100) in Hungary to assess model performance. Results: Prediction for vitality loss for 2025 obtained from the EDM was in agreement with those of the SDM, but for the end of the century the EDM predicted a more serious decline in almost all regions of Hungary. Conclusion: The result of the comparison suggests that the increasing frequency and severity of extremes might play a more important role in limiting the distribution of beech in the future near to the xeric limit than long-term means.

  19. SOLAR ENERGETIC PARTICLE EVENT ASSOCIATED WITH THE 2012 JULY 23 EXTREME SOLAR STORM

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bei; Liu, Ying D.; Hu, Huidong; Wang, Rui; Yang, Zhongwei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G., E-mail: liuxying@spaceweather.ac.cn [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

    2016-08-20

    We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which Solar Terrestrial Relations Observatory (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 the Advanced Composition Explorer and SOlar and Heliospheric Observatory , suggesting 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. Examination of particle intensities, proton anisotropy distributions, element abundance ratios, magnetic connectivity, and spectra also gives important clues for particle acceleration, transport, and distribution.

  20. Impacts of Anthropogenic Aerosols on Regional Climate: Extreme Events, Stagnation, and the United States Warming Hole

    Science.gov (United States)

    Mascioli, Nora R.

    Extreme temperatures, heat waves, heavy rainfall events, drought, and extreme air pollution events have adverse effects on human health, infrastructure, agriculture and economies. The frequency, magnitude and duration of these events are expected to change in the future in response to increasing greenhouse gases and decreasing aerosols, but future climate projections are uncertain. A significant portion of this uncertainty arises from uncertainty in the effects of aerosol forcing: to what extent were the effects from greenhouse gases masked by aerosol forcing over the historical observational period, and how much will decreases in aerosol forcing influence regional and global climate over the remainder of the 21st century? The observed frequency and intensity of extreme heat and precipitation events have increased in the U.S. over the latter half of the 20th century. Using aerosol only (AER) and greenhouse gas only (GHG) simulations from 1860 to 2005 in the GFDL CM3 chemistry-climate model, I parse apart the competing influences of aerosols and greenhouse gases on these extreme events. I find that small changes in extremes in the "all forcing" simulations reflect cancellations between the effects of increasing anthropogenic aerosols and greenhouse gases. In AER, extreme high temperatures and the number of days with temperatures above the 90th percentile decline over most of the U.S., while in GHG high temperature extremes increase over most of the U.S. The spatial response patterns in AER and GHG are significantly anti-correlated, suggesting a preferred regional mode of response that is largely independent of the type of forcing. Extreme precipitation over the eastern U.S. decreases in AER, particularly in winter, and increases over the eastern and central U.S. in GHG, particularly in spring. Over the 21 st century under the RCP8.5 emissions scenario, the patterns of extreme temperature and precipitation change associated with greenhouse gas forcing dominate. The

  1. Stochastic generation of multi-site daily precipitation focusing on extreme events

    Directory of Open Access Journals (Sweden)

    G. Evin

    2018-01-01

    Full Text Available Many multi-site stochastic models have been proposed for the generation of daily precipitation, but they generally focus on the reproduction of low to high precipitation amounts at the stations concerned. This paper proposes significant extensions to the multi-site daily precipitation model introduced by Wilks, with the aim of reproducing the statistical features of extremely rare events (in terms of frequency and magnitude at different temporal and spatial scales. In particular, the first extended version integrates heavy-tailed distributions, spatial tail dependence, and temporal dependence in order to obtain a robust and appropriate representation of the most extreme precipitation fields. A second version enhances the first version using a disaggregation method. The performance of these models is compared at different temporal and spatial scales on a large region covering approximately half of Switzerland. While daily extremes are adequately reproduced at the stations by all models, including the benchmark Wilks version, extreme precipitation amounts at larger temporal scales (e.g., 3-day amounts are clearly underestimated when temporal dependence is ignored.

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

    International Nuclear Information System (INIS)

    1981-01-01

    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)

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

    International Nuclear Information System (INIS)

    2003-03-01

    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

  4. 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.

  5. Necessary and sufficient conditions for big bangs, bounces, crunches, rips, sudden singularities and extremality events

    International Nuclear Information System (INIS)

    Cattoen, Celine; Visser, Matt

    2005-01-01

    Until recently, the physically relevant singularities occurring in FRW cosmologies had traditionally been thought to be limited to the 'big bang', and possibly a 'big crunch'. However, over the last few years, the zoo of cosmological singularities considered in the literature has become considerably more extensive, with 'big rips' and 'sudden singularities' added to the mix, as well as renewed interest in nonsingular cosmological events such as 'bounces' and 'turnarounds'. In this paper we present an extensive catalogue of such cosmological milestones, both at the kinematical and dynamical level. First, using generalized power series, purely kinematical definitions of these cosmological events are provided in terms of the behaviour of the scale factor a(t). The notion of a 'scale-factor singularity' is defined, and its relation to curvature singularities (polynomial and differential) is explored. Second, dynamical information is extracted by using the Friedmann equations (without assuming even the existence of any equation of state) to place constraints on whether or not the classical energy conditions are satisfied at the cosmological milestones. We use these considerations to derive necessary and sufficient conditions for the existence of cosmological milestones such as bangs, bounces, crunches, rips, sudden singularities and extremality events. Since the classification is extremely general and, modulo certain technical assumptions, is complete, the corresponding results are to a high degree model independent: in particular, we provide a characterization of the class of bangs, crunches and sudden singularities for which the dominant energy condition is satisfied

  6. Quantifying the Influence of Global Warming on Unprecedented Extreme Climate Events

    Science.gov (United States)

    Diffenbaugh, Noah S.; Singh, Deepti; Mankin, Justin S.; Horton, Daniel E.; Swain, Daniel L.; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael; hide

    2017-01-01

    Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent.

  7. Extremely high wall-shear stress events in a turbulent boundary layer

    Science.gov (United States)

    Pan, Chong; Kwon, Yongseok

    2018-04-01

    The present work studies the fluctuating characteristics of the streamwise wall-shear stress in a DNS of a turbulent boundary layer at Re τ =1500 from a structural view. The two-dimensional field of the fluctuating friction velocity u‧ τ (x,z) is decomposed into the large- and small-scale components via a recently proposed scale separation algorithm, Quasi-bivariate Variational Mode Decomposition (QB-VMD). Both components are found to be dominated by streak-like structures, which can be regarded as the wall signature of the inner-layer streaks and the outer-layer LSMs, respectively. Extreme positive/negative wall-shear stress fluctuation events are detected in the large-scale component. The former’s occurrence frequency is nearly one order of magnitude higher than the latter; therefore, they contribute a significant portion of the long tail of the wall-shear stress distribution. Both two-point correlations and conditional averages show that these extreme positive wall-shear stress events are embedded in the large-scale positive u‧ τ streaks. They seem to be formed by near-wall ‘splatting’ process, which are related to strong finger-like sweeping (Q4) events originated from the outer-layer positive LSMs.

  8. Quantifying the influence of global warming on unprecedented extreme climate events.

    Science.gov (United States)

    Diffenbaugh, Noah S; Singh, Deepti; Mankin, Justin S; Horton, Daniel E; Swain, Daniel L; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael; Rajaratnam, Bala

    2017-05-09

    Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent.

  9. Preface: Impacts of extreme climate events and disturbances on carbon dynamics

    Science.gov (United States)

    Xiao, Jingfeng; Liu, Shuguang; Stoy, Paul C.

    2016-01-01

    The impacts of extreme climate events and disturbances (ECE&D) on the carbon cycle have received growing attention in recent years. This special issue showcases a collection of recent advances in understanding the impacts of ECE&D on carbon cycling. Notable advances include quantifying how harvesting activities impact forest structure, carbon pool dynamics, and recovery processes; observed drastic increases of the concentrations of dissolved organic carbon and dissolved methane in thermokarst lakes in western Siberia during a summer warming event; disentangling the roles of herbivores and fire on forest carbon dioxide flux; direct and indirect impacts of fire on the global carbon balance; and improved atmospheric inversion of regional carbon sources and sinks by incorporating disturbances. Combined, studies herein indicate several major research needs. First, disturbances and extreme events can interact with one another, and it is important to understand their overall impacts and also disentangle their effects on the carbon cycle. Second, current ecosystem models are not skillful enough to correctly simulate the underlying processes and impacts of ECE&D (e.g., tree mortality and carbon consequences). Third, benchmark data characterizing the timing, location, type, and magnitude of disturbances must be systematically created to improve our ability to quantify carbon dynamics over large areas. Finally, improving the representation of ECE&D in regional climate/earth system models and accounting for the resulting feedbacks to climate are essential for understanding the interactions between climate and ecosystem dynamics.

  10. Hydrological cycle effects on the aquatic community in a Neotropical stream of the Andean piedmont during the 2007-2010 ENSO events.

    Science.gov (United States)

    Ríos-Pulgarín, M I; Barletta, M; Mancera-Rodriguez, N J

    2016-07-01

    The seasonal and interannual changes in the fish, macroinvertebrates and phycoperiphyton assemblages of the Guarinó River were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle and the El Niño-Niña/Southern Oscillation (ENSO) between 2007 and 2010. Four samplings (in dry and rainy seasons) were performed per year. Environmental variables (temperature, pH, conductivity, turbidity, oxygen, total nitrogen, orthophosphate, depth and flow rate) were measured. The temporal patterns of the taxonomic compositions for the three assemblages and the functional composition of fish and macroinvertebrate assemblages with respect to environmental variables were examined through canonical discriminant analysis, multidimensional scaling and multiple correlations. The presence and abundance of fishes, macroinvertebrates and algae species were regulated by environmental variables associated with extreme hydrological events, which derived from the natural torrential regimen of the basin and larger-scale phenomena, such as El Niño and La Niña. Fish abundance and richness were significantly correlated with algal density and pH, the macroinvertebrate density was negatively related to the flow rate and the richness was positively correlated with algal density. The algae richness was positively correlated with pH and negatively correlated with the flow rate and nitrogen. The algal density was positively correlated with pH and temperature and negatively correlated with river flow. The phycoperiphyton assemblage exhibited more direct responses in its density and richness to the hydrological changes (r(2) = 0·743 and 0·800, respectively). In functional terms, the El Niño phenomenon was defined by a greater abundance of omnivorous and insectivorous fishes, as well as filter feeders, scrapers and macroinvertebrate predators. During La Niña, a greater abundance of benthic fishes (both detritivorous and insectivorous) and

  11. Extreme precipitation events in the Iberian Peninsula and its association with Atmospheric Rivers

    Science.gov (United States)

    Ramos, Alexandre M.; Liberato, Margarida L. R.; Trigo, Ricardo M.

    2015-04-01

    Extreme precipitation events in the Iberian Peninsula during the winter half of the year have major socio-economic impacts associated with floods, landslides, extensive property damage and life losses. In recent years, a number of works have shed new light on the role played by Atmospheric Rivers (ARs) in the occurrence of extreme precipitation events in both Europe and USA. ARs are relatively narrow regions of concentrated WV responsible for horizontal transport in the lower atmosphere corresponding to the core section of the broader warm conveyor belt occurring over the oceans along the warm sector of extra-tropical cyclones. Over the North Atlantic ARs 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. It was shown that more than 90% of the meridional WV transport in the mid-latitudes occurs in the AR, although they cover less than 10% of the area of the globe. The large amount of WV that is transported can lead to heavy precipitation and floods. An automated ARs detection algorithm is used for the North Atlantic Ocean Basin allowing the identification and a comprehensive characterization of the major AR events that affected the Iberian Peninsula over the 1948-2012 period. The extreme precipitation days in the Iberian Peninsula were assessed recently by us (Ramos et al., 2014) and their association (or not) with the occurrence of AR is analyzed in detail here. The extreme precipitation days are ranked by their magnitude and are obtained after considering 1) the area affected and 2) the precipitation intensity. Different rankings are presented for the entire Iberian Peninsula, Portugal and also for the six largest Iberian river basins (Minho, Duero, Tagus, Guadiana, Guadalquivir and Ebro) covering the 1950-2008 period (Ramos et al., 2014). Results show that the association between ARs and extreme precipitation days in the western domains (Portugal

  12. Tambora and the mackerel year: phenology and fisheries during an extreme climate event

    Science.gov (United States)

    Alexander, Karen E.; Leavenworth, William B.; Hall, Carolyn; Mattocks, Steven; Bittner, Steven M.; Klein, Emily; Staudinger, Michelle D.; Bryan, Alexander; Rosset, Julianne; Willis, Theodore V.; Carr, Benjamin H.; Jordaan, Adrian

    2017-01-01

    Global warming has increased the frequency of extreme climate events, yet responses of biological and human communities are poorly understood, particularly for aquatic ecosystems and fisheries. Retrospective analysis of known outcomes may provide insights into the nature of adaptations and trajectory of subsequent conditions. We consider the 1815 eruption of the Indonesian volcano Tambora and its impact on Gulf of Maine (GoM) coastal and riparian fisheries in 1816. Applying complex adaptive systems theory with historical methods, we analyzed fish export data and contemporary climate records to disclose human and piscine responses to Tambora’s extreme weather at different spatial and temporal scales while also considering sociopolitical influences. Results identified a tipping point in GoM fisheries induced by concatenating social and biological responses to extreme weather. Abnormal daily temperatures selectively affected targeted fish species—alewives, shad, herring, and mackerel—according to their migration and spawning phenologies and temperature tolerances. First to arrive, alewives suffered the worst. Crop failure and incipient famine intensified fishing pressure, especially in heavily settled regions where dams already compromised watersheds. Insufficient alewife runs led fishers to target mackerel, the next species appearing in abundance along the coast; thus, 1816 became the “mackerel year.” Critically, the shift from riparian to marine fisheries persisted and expanded after temperatures moderated and alewives recovered. We conclude that contingent human adaptations to extraordinary weather permanently altered this complex system. Understanding how adaptive responses to extreme events can trigger unintended consequences may advance long-term planning for resilience in an uncertain future.

  13. Modernizing Distribution System Restoration to Achieve Grid Resiliency Against Extreme Weather Events: An Integrated Solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chen; Wang, Jianhui; Ton, Dan

    2017-07-07

    Recent severe power outages caused by extreme weather hazards have highlighted the importance and urgency of improving the resilience of the electric power grid. As the distribution grids still remain vulnerable to natural disasters, the power industry has focused on methods of restoring distribution systems after disasters in an effective and quick manner. The current distribution system restoration practice for utilities is mainly based on predetermined priorities and tends to be inefficient and suboptimal, and the lack of situational awareness after the hazard significantly delays the restoration process. As a result, customers may experience an extended blackout, which causes large economic loss. On the other hand, the emerging advanced devices and technologies enabled through grid modernization efforts have the potential to improve the distribution system restoration strategy. However, utilizing these resources to aid the utilities in better distribution system restoration decision-making in response to extreme weather events is a challenging task. Therefore, this paper proposes an integrated solution: a distribution system restoration decision support tool designed by leveraging resources developed for grid modernization. We first review the current distribution restoration practice and discuss why it is inadequate in response to extreme weather events. Then we describe how the grid modernization efforts could benefit distribution system restoration, and we propose an integrated solution in the form of a decision support tool to achieve the goal. The advantages of the solution include improving situational awareness of the system damage status and facilitating survivability for customers. The paper provides a comprehensive review of how the existing methodologies in the literature could be leveraged to achieve the key advantages. The benefits of the developed system restoration decision support tool include the optimal and efficient allocation of repair crews

  14. Consequences of hydrological events on the delivery of suspended sediment and associated radionuclides from the Rhone River to the Mediterranean Sea

    Energy Technology Data Exchange (ETDEWEB)

    Eyrolle, Frederique; Antonelli, Christelle; Ferrand, Emmanuelle [IRSN, Saint Paul Lez Durance (France). Pole Radioprotection environnement, dechets et crise, PRP-ENV, Service d' Etude et de Surveillance de la Radioactivite dans l' Environnement; Raimbault, Patrick [Institut Mediterraneen d' Oceanologie, OSU Pytheas, Marseille (France); Aubert, Dominique [CEFREM, Univ. de Perpignan Via Domitia CNRS UMR, Perpignan (France); Jacquet, Stephanie; Radakovitch, Olivier; Raccasi, Guillaume [Aix-Marseille Univ.-CNR-IRD-College de France, Aix en Provence (France); Charmasson, Sabine [IRSN, La Seyne sur mer (France). Pole Radioprotection, environnement, dechets et crise, PRP-ENV, Service d' Etude et de Surveillance de la Radioactivite dans l' Environnement; Gurriaran, Rodolfo [IRSN, Orsay (France). Pole Radioprotection, environnement, dechets et crise, PRP-ENV, Service de Traitement des echantillos et de Metrologie pour l' Environnement

    2012-10-15

    Almost 20 nuclear reactors are situated along the Rhone valley, representing Europe's largest concentration of nuclear power plants. The fate of suspended sediments and natural and artificial particle-bound radionuclides in relation to extreme hydrological events was assessed at the lower course of the Rhone River, which provides the main source of water and sediment inputs to the northwestern Mediterranean Sea. We sampled water at a high frequency over the period 2001-2008 and measured suspended particulate matter (SPM) loads and particle-bound natural and artificial radionuclide concentrations at the SORA observatory station in Arles, France. We monitored various hydrological events (either natural or anthropogenic origin) and characterize their influence on concentrations and fluxes. The relationship between SPM concentration and the very wide range of water discharges did not differ significantly from previous periods, indicating no significant shift in the average sediment delivery over the last 20 years. Unexpected hydrological events of anthropogenic origin, in particular those associated with flushing of reservoirs that are generally not captured by sampling strategies, were recorded and were shown to transfer significant additional sediment and associated contaminants towards the marine environment. Concentrations of anthropogenic radionuclides associated with sediment (i.e., {sup 137}Cs, {sup 60}Co, {sup 54}Mn, {sup 110m}Ag, and Pu isotopes) varied over two to three orders of magnitude during periods of low and moderate flow due to variations in the liquid release from nuclear facilities. Except for Pu isotopes, the concentrations of the various particle-bound radionuclides generally showed a decreasing trend with increasing discharge, revealing the geochemical or anthropogenic background values, and providing a useful flood fingerprint for this large fluvial system before its entry into the marine environment. Our approach produced key data on the

  15. Hydrological simulation of flood transformations in the upper Danube River: Case study of large flood events

    Directory of Open Access Journals (Sweden)

    Mitková Veronika Bačová

    2016-12-01

    Full Text Available The problem of understand natural processes as factors that restrict, limit or even jeopardize the interests of human society is currently of great concern. The natural transformation of flood waves is increasingly affected and disturbed by artificial interventions in river basins. The Danube River basin is an area of high economic and water management importance. Channel training can result in changes in the transformation of flood waves and different hydrographic shapes of flood waves compared with the past. The estimation and evolution of the transformation of historical flood waves under recent river conditions is only possible by model simulations. For this purpose a nonlinear reservoir cascade model was constructed. The NLN-Danube nonlinear reservoir river model was used to simulate the transformation of flood waves in four sections of the Danube River from Kienstock (Austria to Štúrovo (Slovakia under relatively recent river reach conditions. The model was individually calibrated for two extreme events in August 2002 and June 2013. Some floods that occurred on the Danube during the period of 1991–2002 were used for the validation of the model. The model was used to identify changes in the transformational properties of the Danube channel in the selected river reach for some historical summer floods (1899, 1954 1965 and 1975. Finally, a simulation of flood wave propagation of the most destructive Danube flood of the last millennium (August 1501 is discussed.

  16. Extreme events and predictability of catastrophic failure in composite materials and in the Earth

    Science.gov (United States)

    Main, I.; Naylor, M.

    2012-05-01

    Despite all attempts to isolate and predict extreme earthquakes, these nearly always occur without obvious warning in real time: fully deterministic earthquake prediction is very much a `black swan'. On the other hand engineering-scale samples of rocks and other composite materials often show clear precursors to dynamic failure under controlled conditions in the laboratory, and successful evacuations have occurred before several volcanic eruptions. This may be because extreme earthquakes are not statistically special, being an emergent property of the process of dynamic rupture. Nevertheless, probabilistic forecasting of event rate above a given size, based on the tendency of earthquakes to cluster in space and time, can have significant skill compared to say random failure, even in real-time mode. We address several questions in this debate, using examples from the Earth (earthquakes, volcanoes) and the laboratory, including the following. How can we identify `characteristic' events, i.e. beyond the power law, in model selection (do dragon-kings exist)? How do we discriminate quantitatively between stationary and non-stationary hazard models (is a dragon likely to come soon)? Does the system size (the size of the dragon's domain) matter? Are there localising signals of imminent catastrophic failure we may not be able to access (is the dragon effectively invisible on approach)? We focus on the effect of sampling effects and statistical uncertainty in the identification of extreme events and their predictability, and highlight the strong influence of scaling in space and time as an outstanding issue to be addressed by quantitative studies, experimentation and models.

  17. 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

  18. OCCURRENCE OF EXTREME SOLAR PARTICLE EVENTS: ASSESSMENT FROM HISTORICAL PROXY DATA

    Energy Technology Data Exchange (ETDEWEB)

    Usoskin, Ilya G. [Sodankylae Geophysical Observatory (Oulu unit) and Department of Physical Sciences, University of Oulu, FIN-90014 Oulu (Finland); Kovaltsov, Gennady A., E-mail: ilya.usoskin@oulu.fi [Ioffe Physical-Technical Institute of RAS, 194021 St. Petersburg (Russian Federation)

    2012-09-20

    The probability of occurrence of extreme solar particle events (SPEs) with proton fluence (>30 MeV) F{sub 30} {>=} 10{sup 10} cm{sup -2} is evaluated based on data on the cosmogenic isotopes {sup 14}C and {sup 10}Be in terrestrial archives covering centennial-millennial timescales. Four potential candidates with F{sub 30} = (1-1.5) Multiplication-Sign 10{sup 10} cm{sup -2} and no events with F{sub 30} > 2 Multiplication-Sign 10{sup 10} cm{sup -2} are identified since 1400 AD in the annually resolved {sup 10}Be data. A strong SPE related to the Carrington flare of 1859 AD is not supported by the data. For the last 11,400 years, 19 SPE candidates with F{sub 30} = (1-3) Multiplication-Sign 10{sup 10} cm{sup -2} are found and clearly no event with F{sub 30} > 5 Multiplication-Sign 10{sup 10} cm{sup -2} (50 times the SPE of 1956 February 23) has occurred. These values serve as observational upper limits on the strength of SPEs on the timescale of tens of millennia. Two events, ca. 780 and 1460 AD, appear in different data series making them strong candidates for extreme SPEs. We build a distribution of the occurrence probability of extreme SPEs, providing a new strict observational constraint. Practical limits can be set as F{sub 30} Almost-Equal-To 1, 2-3, and 5 Multiplication-Sign 10{sup 10} cm{sup -2} for occurrence probabilities Almost-Equal-To 10{sup -2}, 10{sup -3}, and 10{sup -4} yr{sup -1}, respectively. Because of the uncertainties, our results should be interpreted as a conservative upper limit on the SPE occurrence near Earth. The mean solar energetic particle (SEP) flux is evaluated as Almost-Equal-To 40 (cm{sup 2} s){sup -1}, in agreement with estimates from lunar rocks. On average, extreme SPEs contribute about 10% to the total SEP fluence.

  19. 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.

  20. 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

  1. 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

  2. Two centuries of extreme events over the Baltic Sea and North Sea regions

    Science.gov (United States)

    Stendel, Martin; den Besselaar Else, van; Abdel, Hannachi; Jaak, Jaagus; Elizabeth, Kent; Christiana, Lefebvre; Gudrun, Rosenhagen; Anna, Rutgersson; Frederik, Schenk; der Schrier Gerard, van; Tim, Woolings

    2017-04-01

    Two centuries of extreme events over the Baltic Sea and North Sea regions In the framework of the BACC 2 (for the Baltic Sea) and NOSCCA projects (for the North Sea region), studies of past and present variability and changes in atmospheric variables within the North Sea region over the instrumental period (roughly the past 200 years) have been investigated. Findings on trends in temperature and precipitation have already been presented. Here we focus on data homogeneity issues and examine how reliable reanalyses are in this context. Unlike most other regions in the world, there is a wealth of old observations available for the Baltic and North Sea regions, most of it in handwritten form in meteorological journals and other publications. These datasets need to be carefully digitised and homogenized. For this, a thorough quality control must be applied; otherwise the digitised datasets may prove useless or even counterproductive. We present evidence that this step cannot be conducted without human interference and thus cannot be fully automated. Furthermore, inhomogeneities due to e.g. instrumentation and station relocations need to be addressed. A wealth of reanalysis products is available, which can help detect such inhomogeneities in observed time series, but at the same time are prone to biases and/or spurious trends themselves e.g. introduced by changes in the availability and quality of the underlying assimilated data. It therefore in general remains unclear in how far we can simulate the pre-satellite era with respect to homogeneity with reanalyses based only on parts of the observing system. Extreme events and changes in extreme situations are more important and of greater (societal) significance than changes in mean climate. However, changes in extreme weather events are difficult to assess not only because they are, per definition, rare events, but also due to the homogeneity issues outlined above. Taking these into account, we present evidence for changes

  3. High resolution modelling of the extreme precipitation event over Algiers in November 2001

    Directory of Open Access Journals (Sweden)

    S. A. Moore

    2005-01-01

    Full Text Available Between 18:00UTC on Friday 9th November and 12:00UTC on Saturday 10th November 2001 260mm of rainfall was recorded at Bouzareah, compared to the November average of just 96mm. This extreme rainfall resulted in landslides and flooding, causing immense damage to the Bab-el-Oued district of Algiers and affected the lives of more than 2000 people. In this paper, key results from a modelling study of this event using the UK Met Office Unified Model at global (60km, regional (20km and national (4km horizontal resolutions are described. In general, it is found that the event could be well forecast with increases in resolution leading to better predictions of both the distribution and intensity of the rainfall. The role of the local orography and latent heating are also discussed.

  4. A study of upward going particles with the Extreme Energy Events telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Abbrescia, M. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Fisica, Università di Bari, Bari (Italy); Avanzini, C.; Baldini, L. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Fisica, Università di Pisa, Pisa (Italy); Ferroli, R. Baldini [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN Laboratori Nazionali di Frascati, Frascati (RM) (Italy); Batignani, G. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Fisica, Università di Pisa, Pisa (Italy); Bencivenni, G. [INFN Laboratori Nazionali di Frascati, Frascati (RM) (Italy); Bossini, E. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN Gruppo Collegato di Siena and Dipartimento di Fisica, Università di Siena, Siena (Italy); Chiavassa, A. [INFN and Dipartimento di Fisica, Università di Torino, Torino (Italy); Cicalo, C. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Cifarelli, L. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Fisica, Università di Bologna, Bologna (Italy); Coccia, E. [INFN and Dipartimento di Fisica, Università di Roma Tor Vergata, Roma (Italy); Corvaglia, A. [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma (Italy); INFN and Dipartimento di Matematica e Fisica, Università del Salento, Lecce (Italy); and others

    2016-04-21

    In this paper the first study of the upward going events detected by the telescopes of the Extreme Energy Event (EEE) project is reported. The EEE project consists of a detector array of Multigap Resistive Plate Chambers located at selected sites on the Italian territory. During autumn 2014 the first coordinated data taking period took place and around one billion candidate tracks were collected. Among them, of particular interest is the sample of particles which cross the telescopes from below. The results obtained demonstrate that the EEE telescopes can distinguish the electrons produced as decay products of cosmic muons stopped in the ground, or in the last chamber of the telescopes themselves, confirming the excellent performance of the system for the investigation of intriguing cosmic phenomena.

  5. 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

  6. CrossRef A study of upward going particles with the Extreme Energy Events telescopes

    CERN Document Server

    Abbrescia, M; Baldini, L; Ferroli, R Baldini; Batignani, G; Bencivenni, G; Bossini, E; Chiavassa, A; Cicalo, 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; Ferraro, A; Forster, R; Frolov, V; Galeotti, P; Garbini, M; Gemme, G; Gnesi, I; Grazzi, S; Gustavino, C; Hatzifotiadu, D; La Rocca, P; Maggiora, A; Maron, G; Mazziotta, M N; Miozzi, S; Nania, R; Noferini, F; Nozzoli, F; Panareo, M; Panetta, M P; Paoletti, R; Perasso, L; Pilo, F; Piragino, G; Riggi, F; Righini, G C; Rodriguez, A R; Sartorelli, G; Scapparone, E; Schioppa, M; Scribano, A; Selvi, M; Serci, S; Siddi, E; Squarcia, S; Stori, L; Taiuti, M; Terreni, G; Vistoli, M C; Votano, L; Williams, M C S; Zani, S; Zichichi, A; Zuyeuski, R

    2016-01-01

    In this paper the first study of the upward going events detected by the telescopes of the Extreme Energy Event (EEE) project is reported. The EEE project consists of a detector array of Multigap Resistive Plate Chambers located at selected sites on the Italian territory. During autumn 2014 the first coordinated data taking period took place and around one billion candidate tracks were collected. Among them, of particular interest is the sample of particles which cross the telescopes from below. The results obtained demonstrate that the EEE telescopes can distinguish the electrons produced as decay products of cosmic muons stopped in the ground, or in the last chamber of the telescopes themselves, confirming the excellent performance of the system for the investigation of intriguing cosmic phenomena.

  7. Extreme flood event analysis in Indonesia based on rainfall intensity and recharge capacity

    Science.gov (United States)

    Narulita, Ida; Ningrum, Widya

    2018-02-01

    Indonesia is very vulnerable to flood disaster because it has high rainfall events throughout the year. Flood is categorized as the most important hazard disaster because it is causing social, economic and human losses. The purpose of this study is to analyze extreme flood event based on satellite rainfall dataset to understand the rainfall characteristic (rainfall intensity, rainfall pattern, etc.) that happened before flood disaster in the area for monsoonal, equatorial and local rainfall types. Recharge capacity will be analyzed using land cover and soil distribution. The data used in this study are CHIRPS rainfall satellite data on 0.05 ° spatial resolution and daily temporal resolution, and GSMap satellite rainfall dataset operated by JAXA on 1-hour temporal resolution and 0.1 ° spatial resolution, land use and soil distribution map for recharge capacity analysis. The rainfall characteristic before flooding, and recharge capacity analysis are expected to become the important information for flood mitigation in Indonesia.

  8. A study of upward going particles with the Extreme Energy Events telescopes

    International Nuclear Information System (INIS)

    Abbrescia, M.; Avanzini, C.; Baldini, L.; Ferroli, R. Baldini; Batignani, G.; Bencivenni, G.; Bossini, E.; Chiavassa, A.; Cicalo, C.; Cifarelli, L.; Coccia, E.; Corvaglia, A.

    2016-01-01

    In this paper the first study of the upward going events detected by the telescopes of the Extreme Energy Event (EEE) project is reported. The EEE project consists of a detector array of Multigap Resistive Plate Chambers located at selected sites on the Italian territory. During autumn 2014 the first coordinated data taking period took place and around one billion candidate tracks were collected. Among them, of particular interest is the sample of particles which cross the telescopes from below. The results obtained demonstrate that the EEE telescopes can distinguish the electrons produced as decay products of cosmic muons stopped in the ground, or in the last chamber of the telescopes themselves, confirming the excellent performance of the system for the investigation of intriguing cosmic phenomena.

  9. Weakened cyclones, intensified anticyclones and recent extreme cold winter weather events in Eurasia

    International Nuclear Information System (INIS)

    Zhang Xiangdong; Lu Chuhan; Guan Zhaoyong

    2012-01-01

    Extreme cold winter weather events over Eurasia have occurred more frequently in recent years in spite of a warming global climate. To gain further insight into this regional mismatch with the global mean warming trend, we analyzed winter cyclone and anticyclone activities, and their interplay with the regional atmospheric circulation pattern characterized by the semi-permanent Siberian high. We found a persistent weakening of both cyclones and anticyclones between the 1990s and early 2000s, and a pronounced intensification of anticyclone activity afterwards. It is suggested that this intensified anticyclone activity drives the substantially strengthening and northwestward shifting/expanding Siberian high, and explains the decreased midlatitude Eurasian surface air temperature and the increased frequency of cold weather events. The weakened tropospheric midlatitude westerlies in the context of the intensified anticyclones would reduce the eastward propagation speed of Rossby waves, favoring persistence and further intensification of surface anticyclone systems. (letter)

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

    International Nuclear Information System (INIS)

    Pascal, M.; Pirard, P.; Medina, S.; Viso, A.C.; Caserio-Schonemann, C.; Beaudeau, P.

    2013-01-01

    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)

  11. 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).

  12. 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.

  13. Evolution in Intensity and Frequency of Extreme Events of Precipitation in Northeast Region and Brazilian Amazon in XXI Century

    Science.gov (United States)

    Fonseca, P. M.; Veiga, J. A.; Correia, F. S.; Brito, A. L.

    2013-05-01

    The aim of this research was evaluate changes in frequency and intensity of extreme events of precipitation in Brazilian Amazon and Northeast Region, doubling CO2 concentration in agreement of IPCC A2 emissions scenarios (Nakicenovic et al., 2001). For this evaluation was used ETA model (Chou et al., 2011), forced with CCSM3 Global model data (Meehl, 2006) to run 4 experiments, only for January, February and March: 1980-1990, 2000-2010, 2040-2050 and 2090-2100. Using the first decade as reference (1980-1990), was evaluated changes occurred in following decades, with a methodology to classify extremes events adapted from Frich (2002) and Gao (2006). Higher was the class, more intense is the event. An increase of 25% was observed in total precipitation in Brazilian Amazon for the end of XXI century and 12% for extreme events type 1, 9% for events type 2 and 10% for type 3. By the other hand, a 17% decrease of precipitation in Brazilian Northeast was observed, and a pronounced decay of 24% and 15% in extreme events contribution type 1 and 2 to total amount of precipitation, respectively. The difference between total normal type events was positive in this three decades compared with reference decade 1980-1990, varying positively from 4 to 6 thousand events included in normality by decade, these events was decreased in your majority of Class 1 events, which presented a decay of at least 3.500 events by each decade. This suggests an intensification of extreme events, considering that the amount of precipitation by class increased, and the number of events by class decreased. To Northeast region, an increasing in 9% of contribution to events type 3 class was observed, as well as in the frequency of this type of events (about of 700 more events). Major decreasing in number of classes extreme events occur in 2000-2010, to classes 1 and 3, with 7,2 and 5,6%, and by the end of century in class 3, with 4,5%. For the three analyzed decades a total decrease of 8.400 events was

  14. Overrepresentation of extreme events in decision making reflects rational use of cognitive resources.

    Science.gov (United States)

    Lieder, Falk; Griffiths, Thomas L; Hsu, Ming

    2018-01-01

    People's decisions and judgments are disproportionately swayed by improbable but extreme eventualities, such as terrorism, that come to mind easily. This article explores whether such availability biases can be reconciled with rational information processing by taking into account the fact that decision makers value their time and have limited cognitive resources. Our analysis suggests that to make optimal use of their finite time decision makers should overrepresent the most important potential consequences relative to less important, put potentially more probable, outcomes. To evaluate this account, we derive and test a model we call utility-weighted sampling. Utility-weighted sampling estimates the expected utility of potential actions by simulating their outcomes. Critically, outcomes with more extreme utilities have a higher probability of being simulated. We demonstrate that this model can explain not only people's availability bias in judging the frequency of extreme events but also a wide range of cognitive biases in decisions from experience, decisions from description, and memory recall. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  15. 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

    2017-04-01

    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.

  16. 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.

    , destruction of shorefront dwellings, formation of inlets and new water bodies. Extreme events confirmed that sand dunes and dense forests possess an innate capacity of attenuating wave up-rush, evidenced respectively by negligible overwash, and by modest...

  17. Investigating the Origins of Two Extreme Solar Particle Events: Proton Source Profile and Associated Electromagnetic Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Kocharov, Leon; Usoskin, Ilya [Sodankylä Geophysical Observatory/Oulu Unit, University of Oulu, P.O.B. 3000, Oulu FI-90014 (Finland); Pohjolainen, Silja [Tuorla Observatory, University of Turku, Piikkiö FI-21500 (Finland); Mishev, Alexander [Space Climate Research Unit, University of Oulu, Oulu FI-90014 (Finland); Reiner, Mike J. [The Catholic University of America, Washington, DC, and NASA/Goddard Space Flight Center, Greenbelt, MD (United States); Lee, Jeongwoo [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Laitinen, Timo [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Didkovsky, Leonid V. [University of Southern California Space Sciences Center, 835 Bloom Walk, Los Angeles CA 90089 (United States); Pizzo, Victor J. [NOAA Space Weather Prediction Center, Boulder, CO 80305 (United States); Kim, Roksoon; Cho, Kyung-Suk [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Klassen, Andreas [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, Kiel D-24118 (Germany); Karlicky, Marian [Astronomical Institute of the Czech Academy of Sciences, Fričova 258, Ondřejov 251 65 (Czech Republic); Gary, Dale E. [Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark NJ 07102-1982 (United States); Valtonen, Eino; Vainio, Rami [Space Research Laboratory, University of Turku, Turku FI-20014 (Finland)

    2017-04-20

    We analyze the high-energy particle emission from the Sun in two extreme solar particle events in which protons are accelerated to relativistic energies and can cause a significant signal even in the ground-based particle detectors. Analysis of a relativistic proton event is based on modeling of the particle transport and interaction, from a near-Sun source through the solar wind and the Earth’s magnetosphere and atmosphere to a detector on the ground. This allows us to deduce the time profile of the proton source at the Sun and compare it with observed electromagnetic emissions. The 1998 May 2 event is associated with a flare and a coronal mass ejection (CME), which were well observed by the Nançay Radioheliograph, thus the images of the radio sources are available. For the 2003 November 2 event, the low corona images of the CME liftoff obtained at the Mauna Loa Solar Observatory are available. Those complementary data sets are analyzed jointly with the broadband dynamic radio spectra, EUV images, and other data available for both events. We find a common scenario for both eruptions, including the flare’s dual impulsive phase, the CME-launch-associated decimetric-continuum burst, and the late, low-frequency type III radio bursts at the time of the relativistic proton injection into the interplanetary medium. The analysis supports the idea that the two considered events start with emission of relativistic protons previously accelerated during the flare and CME launch, then trapped in large-scale magnetic loops and later released by the expanding CME.

  18. 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.

  19. 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

  20. Extreme events as foundation of Lévy walks with varying velocity

    Science.gov (United States)

    Kutner, Ryszard

    2002-11-01

    In this work we study the role of extreme events [E.W. Montroll, B.J. West, in: J.L. Lebowitz, E.W. Montrell (Eds.), Fluctuation Phenomena, SSM, vol. VII, North-Holland, Amsterdam, 1979, p. 63; J.-P. Bouchaud, M. Potters, Theory of Financial Risks from Statistical Physics to Risk Management, Cambridge University Press, Cambridge, 2001; D. Sornette, Critical Phenomena in Natural Sciences. Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, Springer, Berlin, 2000] in determining the scaling properties of Lévy walks with varying velocity. This model is an extension of the well-known Lévy walks one [J. Klafter, G. Zumofen, M.F. Shlesinger, in M.F. Shlesinger, G.M. Zaslavsky, U. Frisch (Eds.), Lévy Flights and Related Topics ion Physics, Lecture Notes in Physics, vol. 450, Springer, Berlin, 1995, p. 196; G. Zumofen, J. Klafter, M.F. Shlesinger, in: R. Kutner, A. Pȩkalski, K. Sznajd-Weron (Eds.), Anomalous Diffusion. From Basics to Applications, Lecture Note in Physics, vol. 519, Springer, Berlin, 1999, p. 15] introduced in the context of chaotic dynamics where a fixed value of the walker velocity is assumed for simplicity. Such an extension seems to be necessary when the open and/or complex system is studied. The model of Lévy walks with varying velocity is spanned on two coupled velocity-temporal hierarchies: the first one consisting of velocities and the second of corresponding time intervals which the walker spends between the successive turning points. Both these hierarchical structures are characterized by their own self-similar dimensions. The extreme event, which can appear within a given time interval, is defined as a single random step of the walker having largest length. By finding power-laws which describe the time-dependence of this displacement and its statistics we obtained two independent diffusion exponents, which are related to the above-mentioned dimensions and which characterize the extreme event kinetics. In this work we show the

  1. Series distance – an intuitive metric to quantify hydrograph similarity in terms of occurrence, amplitude and timing of hydrological events

    Directory of Open Access Journals (Sweden)

    U. Ehret

    2011-03-01

    Full Text Available Applying metrics to quantify the similarity or dissimilarity of hydrographs is a central task in hydrological modelling, used both in model calibration and the evaluation of simulations or forecasts. Motivated by the shortcomings of standard objective metrics such as the Root Mean Square Error (RMSE or the Mean Absolute Peak Time Error (MAPTE and the advantages of visual inspection as a powerful tool for simultaneous, case-specific and multi-criteria (yet subjective evaluation, we propose a new objective metric termed Series Distance, which is in close accordance with visual evaluation. The Series Distance quantifies the similarity of two hydrographs neither in a time-aggregated nor in a point-by-point manner, but on the scale of hydrological events. It consists of three parts, namely a Threat Score which evaluates overall agreement of event occurrence, and the overall distance of matching observed and simulated events with respect to amplitude and timing. The novelty of the latter two is the way in which matching point pairs on the observed and simulated hydrographs are identified: not by equality in time (as is the case with the RMSE, but by the same relative position in matching segments (rise or recession of the event, indicating the same underlying hydrological process. Thus, amplitude and timing errors are calculated simultaneously but separately, from point pairs that also match visually, considering complete events rather than only individual points (as is the case with MAPTE. Relative weights can freely be assigned to each component of the Series Distance, which allows (subjective customization of the metric to various fields of application, but in a traceable way. Each of the three components of the Series Distance can be used in an aggregated or non-aggregated way, which makes the Series Distance a suitable tool for differentiated, process-based model diagnostics.

    After discussing the applicability of established time series

  2. Characteristics of storms that contribute to extreme precipitation events over the Iberian Peninsula

    Science.gov (United States)

    Trigo, Ricardo; Ramos, Alexandre M.; Ordoñez, Paulina; Liberato, Margarida L. R.; Trigo, Isabel F.

    2014-05-01

    Floods correspond to one of the most deadly natural disasters in the Iberian Peninsula during the last century. Quite often these floods are associated to intense low pressure systems with an Atlantic origin. In recent years a number of episodes have been evaluated on a case-by-case approach, with a clear focus on extreme events, thus lacking a systematic assessment. In this study we focus on the characteristics of storms for the extended winter season (October to March) that are responsible for the most extreme rainfall events over large areas of the Iberian Peninsula. An objective method for ranking daily precipitation events during the extended winter is used based on the most comprehensive database of high resolution (0.2º latitude by 0.2º longitude) gridded daily precipitation dataset available for the Iberian Peninsula. The magnitude of an event is obtained after considering the total area affected as well as its intensity in every grid point (taking into account the daily normalised departure from climatology). Different precipitation rankings are studied considering the entire Iberian Peninsula, Portugal and also the six largest river basins in the Iberian Peninsula (Duero, Ebro, Tagus, Minho, Guadiana and Guadalquivir). Using an objective cyclone detecting and tracking scheme [Trigo, 2006] the storm track and characteristics of the cyclones were obtained using the ERA-Interim reanalyses for the 1979-2008 period. The spatial distribution of extratropical cyclone positions when the precipitation extremes occur will be analysed over the considered sub-domains (Iberia, Portugal, major river basins). In addition, we distinguish the different cyclone characteristics (lifetime, direction, minimum pressure, position, velocity, vorticity and radius) with significant impacts in precipitation over the different domains in the Iberian Peninsula. This work was partially supported by FEDER (Fundo Europeu de Desenvolvimento Regional) funds through the COMPETE (Programa

  3. 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

  4. Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach

    Science.gov (United States)

    Ortega, Pablo; Guilyardi, Eric; Swingedouw, Didier; Mignot, Juliette; Nguyen, Sébastien

    2017-11-01

    While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades.

  5. Impact of agricultural management on pluvial flash floods - Case study of an extreme event observed in Austria in 2016

    Science.gov (United States)

    Lumassegger, Simon; Achleitner, Stefan; Kohl, Bernhard

    2017-04-01

    Central Europe was affected by extreme flash floods in summer 2016 triggered by short, high-intensity storm cells. Besides fluvial runoff, local pluvial floods appear to increase recently. In frame of the research project SAFFER-CC (sensitivity assessment of critical condition for local flash floods - evaluating the recurrence under climate change) surface runoff and pluvial flooding is assessed using a coupled hydrological/2D hydrodynamic model for the severely affected municipality of Schwertberg, Upper Austria. In this small catchment several flooding events occurred in the last years, where the most severe event occurred during summer 2016. Several areas could only be reached after the flood wave subsided with observed flood marks up to one meter. The modeled catchment is intensively cultivated with maize, sugar beets, winter wheat and soy on the hillside and hence highly vulnerable to water erosion. The average inclination is relatively steep with 15 % leading to high flow velocities of surface runoff associated with large amounts of transported sediments. To assess the influence of land use and soil conservation on flash floods, field experiments with a portable irrigation spray installation were carried out at different locations. The test plots were subjected to rainfall with constant intensity of 100 mm/h for one hour. Consecutively a super intense, one hour lasting, rainfall hydrograph was applied after 30 minutes at the same plots, ranging from 50 mm/h to 200 mm/h. Surface runoff was collected and measured in a tank and water samples were taken to determine the suspended material load. Large differences of runoff coefficients were determined depending on the agricultural management. The largest discharge was measured in a maize field, where surface runoff occurred immediately after start of irrigation. The determined runoff coefficients ranged from 0.22 for soy up to 0.65 for maize for the same soil type and inclination. The conclusion that runoff is

  6. The potential impacts of climate variability and change on health impacts of extreme weather events in the United States.

    Science.gov (United States)

    Greenough, G; McGeehin, M; Bernard, S M; Trtanj, J; Riad, J; Engelberg, D

    2001-05-01

    Extreme weather events such as precipitation extremes and severe storms cause hundreds of deaths and injuries annually in the United States. Climate change may alter the frequency, timing, intensity, and duration of these events. Increases in heavy precipitation have occurred over the past century. Future climate scenarios show likely increases in the frequency of extreme precipitation events, including precipitation during hurricanes, raising the risk of floods. Frequencies of tornadoes and hurricanes cannot reliably be projected. Injury and death are the direct health impacts most often associated with natural disasters. Secondary effects, mediated by changes in ecologic systems and public health infrastructure, also occur. The health impacts of extreme weather events hinge on the vulnerabilities and recovery capacities of the natural environment and the local population. Relevant variables include building codes, warning systems, disaster policies, evacuation plans, and relief efforts. There are many federal, state, and local government agencies and nongovernmental organizations involved in planning for and responding to natural disasters in the United States. Future research on health impacts of extreme weather events should focus on improving climate models to project any trends in regional extreme events and as a result improve public health preparedness and mitigation. Epidemiologic studies of health effects beyond the direct impacts of disaster will provide a more accurate measure of the full health impacts and will assist in planning and resource allocation.

  7. Development of an Evaluation Methodology for Loss of Large Area induced from extreme events

    International Nuclear Information System (INIS)

    Kim, Sok Chul; Park, Jong Seuk; Kim, Byung Soon; Jang, Dong Ju; Lee, Seung Woo

    2015-01-01

    USNRC announced several regulatory requirements and guidance documents regarding the event of loss of large area including 10CFR 50.54(hh), Regulatory Guide 1.214 and SRP 19.4. In Korea, consideration of loss of large area has been limitedly taken into account for newly constructing NPPs as voluntary based. In general, it is hardly possible to find available information on methodology and key assumptions for the assessment of LOLA due to 'need to know based approach'. Urgent needs exists for developing country specific regulatory requirements, guidance and evaluation methodology by themselves with the consideration of their own geographical and nuclear safety and security environments. Currently, Korea Hydro and Nuclear Power Company (KHNP) has developed an Extended Damage Mitigation Guideline (EDMG) for APR1400 under contract with foreign consulting company. The submittal guidance NEI 06-12 related to B.5.b Phase 2 and 3 focused on unit-wise mitigation strategy instead of site level mitigation or response strategy. Phase 1 mitigating strategy and guideline for LOLA (Loss of Large Area) provides emphasis on site level arrangement including cooperative networking outside organizations and agile command and control system. Korea Institute of Nuclear Safety has carried out a pilot in-house research project to develop the methodology and guideline for evaluation of LOLA since 2014. This paper introduces the summary of major results and outcomes of the aforementioned research project. After Fukushima Dai-Ichi accident, the awareness on countering the event of loss of large area induced from extreme man-made hazards or extreme beyond design basis external event. Urgent need exists to develop regulatory guidance for coping with this undesirable situation, which has been out of consideration at existing nuclear safety regulatory framework due to the expectation of rare possibility of occurrence

  8. LISA extreme-mass-ratio inspiral events as probes of the black hole mass function

    International Nuclear Information System (INIS)

    Gair, Jonathan R.; Tang, Christopher; Volonteri, Marta

    2010-01-01

    One of the sources of gravitational waves for the proposed space-based gravitational wave detector, the Laser Interferometer Space Antenna (LISA), are the inspirals of compact objects into supermassive black holes in the centers of galaxies--extreme-mass-ratio inspirals (EMRIs). Using LISA observations, we will be able to measure the parameters of each EMRI system detected to very high precision. However, the statistics of the set of EMRI events observed by LISA will be more important in constraining astrophysical models than extremely precise measurements for individual systems. The black holes to which LISA is most sensitive are in a mass range that is difficult to probe using other techniques, so LISA provides an almost unique window onto these objects. In this paper we explore, using Bayesian techniques, the constraints that LISA EMRI observations can place on the mass function of black holes at low redshift. We describe a general framework for approaching inference of this type--using multiple observations in combination to constrain a parametrized source population. Assuming that the scaling of the EMRI rate with the black-hole mass is known and taking a black-hole distribution given by a simple power law, dn/dlnM=A 0 (M/M * ) α 0 , we find that LISA could measure the parameters to a precision of Δ(lnA 0 )∼0.08, and Δ(α 0 )∼0.03 for a reference model that predicts ∼1000 events. Even with as few as 10 events, LISA should constrain the slope to a precision ∼0.3, which is the current level of observational uncertainty in the low-mass slope of the black-hole mass function. We also consider a model in which A 0 and α 0 evolve with redshift, but find that EMRI observations alone do not have much power to probe such an evolution.

  9. 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.

  10. Extreme climatic events constrain space use and survival of a ground-nesting bird.

    Science.gov (United States)

    Tanner, Evan P; Elmore, R Dwayne; Fuhlendorf, Samuel D; Davis, Craig A; Dahlgren, David K; Orange, Jeremy P

    2017-05-01

    Two fundamental issues in ecology are understanding what influences the distribution and abundance of organisms through space and time. While it is well established that broad-scale patterns of abiotic and biotic conditions affect organisms' distributions and population fluctuations, discrete events may be important drivers of space use, survival, and persistence. These discrete extreme climatic events can constrain populations and space use at fine scales beyond that which is typically measured in ecological studies. Recently, a growing body of literature has identified thermal stress as a potential mechanism in determining space use and survival. We sought to determine how ambient temperature at fine temporal scales affected survival and space use for a ground-nesting quail species (Colinus virginianus; northern bobwhite). We modeled space use across an ambient temperature gradient (ranging from -20 to 38 °C) through a maxent algorithm. We also used Andersen-Gill proportional hazard models to assess the influence of ambient temperature-related variables on survival through time. Estimated available useable space ranged from 18.6% to 57.1% of the landscape depending on ambient temperature. The lowest and highest ambient temperature categories (35 °C, respectively) were associated with the least amount of estimated useable space (18.6% and 24.6%, respectively). Range overlap analysis indicated dissimilarity in areas where Colinus virginianus were restricted during times of thermal extremes (range overlap = 0.38). This suggests that habitat under a given condition is not necessarily a habitat under alternative conditions. Further, we found survival was most influenced by weekly minimum ambient temperatures. Our results demonstrate that ecological constraints can occur along a thermal gradient and that understanding the effects of these discrete events and how they change over time may be more important to conservation of organisms than are average and broad

  11. The role of forest type on throughfall during extreme precipitation events - A comparison of methods using data from the Pohorje mountains (NE Slovenia)

    Science.gov (United States)

    Vilhar, Urša; Simončič, Primož

    2013-04-01

    Extreme precipitation in the Alpine region is a major environmental factor due to high frequency of such events and consequences such as flooding of populated valley floors, erosion, avalanches, debris flow and landslides endangering exposed settlements. However, the effects of extreme precipitation are buffered by forest cover, therefore forest management practices should aim towards decreased surface runoff and soil erosion in alpine climates. In Central Europe, many pure Norway spruce stands, established on primary beech sites, were converted into mixed stands over the last 60 years. The conversion of forest management from spruce monocultures into mixed deciduous-coniferous forests changed the forest structure dramatically. This changes could influence the hydrological processes on the catchment scale, associated with major river flooding following extreme precipitation events. In this study, the effect of forest management on the partitioning of rainfall into throughfall and stemflow in coniferous and mixed deciduous-coniferous stands on Pohorje mountains in NE Slovenia were investigated. Four spruce Picea abies (L. Karst) stands were compared to four mixed spruce-beech Fagus sylvatica (L.) stands with prevailing forest plant community Cardamine Savensi Fagetum with small areas of Sphagno - Piceetum, Bazzanio - Piceetum and Rhytidiodelpholorei - Piceetum intermixed. The monthly throughfall from rain collectors and half-hourly throughfall from automated rain gauges in growing seasons from 2008 till 2012 were analyzed in order to estimate the throughfall under forest canopies. In the mixed spruce-beech stands the monthly stemflow on beech trees was also measured. For the precipitation in the open an automated weather station and rainfall collectors in an open area located very close to the research plots were used. There were small differences in seasonal throughfall found between the coniferous and mixed deciduous-coniferous stands. The seasonal throughfall was

  12. A Participatory Modeling Application of a Distributed Hydrologic Model in Nuevo Leon, Mexico for the 2010 Hurricane Alex Flood Event

    Science.gov (United States)

    Baish, A. S.; Vivoni, E. R.; Payan, J. G.; Robles-Morua, A.; Basile, G. M.

    2011-12-01

    A distributed hydrologic model can help bring consensus among diverse stakeholders in regional flood planning by producing quantifiable sets of alternative futures. This value is acute in areas with high uncertainties in hydrologic conditions and sparse observations. In this study, we conduct an application of the Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) in the Santa Catarina basin of Nuevo Leon, Mexico, where Hurricane Alex in July 2010 led to catastrophic flooding of the capital city of Monterrey. Distributed model simulations utilize best-available information on the regional topography, land cover, and soils obtained from Mexican government agencies or analysis of remotely-sensed imagery from MODIS and ASTER. Furthermore, we developed meteorological forcing for the flood event based on multiple data sources, including three local gauge networks, satellite-based estimates from TRMM and PERSIANN, and the North American Land Data Assimilation System (NLDAS). Remotely-sensed data allowed us to quantify rainfall distributions in the upland, rural portions of the Santa Catarina that are sparsely populated and ungauged. Rural areas had significant contributions to the flood event and as a result were considered by stakeholders for flood control measures, including new reservoirs and upland vegetation management. Participatory modeling workshops with the stakeholders revealed a disconnect between urban and rural populations in regard to understanding the hydrologic conditions of the flood event and the effectiveness of existing and potential flood control measures. Despite these challenges, the use of the distributed flood forecasts developed within this participatory framework facilitated building consensus among diverse stakeholders and exploring alternative futures in the basin.

  13. Developing a Framework for Seamless Prediction of Sub-Seasonal to Seasonal Extreme Precipitation Events in the United States.

    Science.gov (United States)

    Rosendahl, D. H.; Ćwik, P.; Martin, E. R.; Basara, J. B.; Brooks, H. E.; Furtado, J. C.; Homeyer, C. R.; Lazrus, H.; Mcpherson, R. A.; Mullens, E.; Richman, M. B.; Robinson-Cook, A.

    2017-12-01

    Extreme precipitation events cause significant damage to homes, businesses, infrastructure, and agriculture, as well as many injures and fatalities as a result of fast-moving water or waterborne diseases. In the USA, these natural hazard events claimed the lives of more than 300 people during 2015 - 2016 alone, with total damage reaching $24.4 billion. Prior studies of extreme precipitation events have focused on the sub-daily to sub-weekly timeframes. However, many decisions for planning, preparing and resilience-building require sub-seasonal to seasonal timeframes (S2S; 14 to 90 days), but adequate forecasting tools for prediction do not exist. Therefore, the goal of this newly funded project is an enhancement in understanding of the large-scale forcing and dynamics of S2S extreme precipitation events in the United States, and improved capability for modeling and predicting such events. Here, we describe the project goals, objectives, and research activities that will take place over the next 5 years. In this project, a unique team of scientists and stakeholders will identify and understand weather and climate processes connected with the prediction of S2S extreme precipitation events by answering these research questions: 1) What are the synoptic patterns associated with, and characteristic of, S2S extreme precipitation evens in the contiguous U.S.? 2) What role, if any, do large-scale modes of climate variability play in modulating these events? 3) How predictable are S2S extreme precipitation events across temporal scales? 4) How do we create an informative prediction of S2S extreme precipitation events for policymaking and planing? This project will use observational data, high-resolution radar composites, dynamical climate models and workshops that engage stakeholders (water resource managers, emergency managers and tribal environmental professionals) in co-production of knowledge. The overarching result of this project will be predictive models to reduce of

  14. A long record of extreme wave events in coastal Lake Hamana, Japan

    Science.gov (United States)

    Boes, Evelien; Yokoyama, Yusuke; Schmidt, Sabine; Riedesel, Svenja; Fujiwara, Osamu; Nakamura, Atsunori; Garrett, Ed; Heyvaert, Vanessa; Brückner, Helmut; De Batist, Marc

    2017-04-01

    Coastal Lake Hamana is located near the convergent tectonic boundary of the Nankai-Suruga Trough, along which the Philippine Sea slab is subducted underneath the Eurasian Plate, giving rise to repeated tsunamigenic megathrust earthquakes (Mw ≥ 8). A good understanding of the earthquake- and tsunami-triggering mechanisms is crucial in order to better estimate the complexity of seismic risks. Thanks to its accommodation space, Lake Hamana may represent a good archive for past events, such as tsunamis and tropical storms (typhoons), also referred to as "extreme wave" events. Characteristic event layers, consisting of sediment entrained by these extreme waves and their backwash, are witnesses of past marine incursions. By applying a broad range of surveying methods (reflection-seismic profiling, gravity coring, piston coring), sedimentological analyses (CT-scanning, XRF-scanning, multi-sensor core logging, grain size, microfossils etc.) and dating techniques (210Pb/137Cs, 14C, OSL, tephrochronology), we attempt to trace extreme wave event deposits in a multiproxy approach. Seismic imagery shows a vertical stacking of stronger reflectors, interpreted to be coarser-grained sheets deposited by highly energetic waves. Systematic sampling of lake bottom sediments along a transect from ocean-proximal to ocean-distal sites enables us to evaluate vertical and lateral changes in stratigraphy. Ocean-proximal, we observe a sequence of eight sandy units separated by silty background sediments, up to a depth of 8 m into the lake bottom. These sand layers quickly thin out and become finer-grained land-inward. Seismic-to-core correlations show a good fit between the occurrence of strong reflectors and sandy deposits, hence confirming presumptions based on acoustic imagery alone. Sand-rich intervals typically display a higher magnetic susceptibility, density and stronger X-ray attenuation. However, based on textural and structural differences, we can make the distinction between

  15. The CAULDRON game: Helping decision makers understand extreme weather event attribution

    Science.gov (United States)

    Walton, P.; Otto, F. E. L.

    2014-12-01

    There is a recognition from academics and stakeholders that climate science has a fundamental role to play in the decision making process, but too frequently there is still uncertainty about what, when, how and why to use it. Stakeholders suggest that it is because the science is presented in an inaccessible manner, while academics suggest it is because the stakeholders do not have the scientific knowledge to understand and apply the science appropriately. What is apparent is that stakeholders need support, and that there is an onus on academia to provide it. This support is even more important with recent developments in climate science, such as extreme weather event attribution. We are already seeing the impacts of extreme weather events around the world causing lost of life and damage to property and infrastructure with current research suggesting that these events could become more frequent and more intense. If this is to be the case then a better understanding of the science will be vital in developing robust adaptation and business planning. The use of games, role playing and simulations to aid learning has long been understood in education but less so as a tool to support stakeholder understanding of climate science. Providing a 'safe' space where participants can actively engage with concepts, ideas and often emotions, can lead to deep understanding that is not possible through more passive mechanisms such as papers and web sites. This paper reports on a game that was developed through a collaboration led by the Red Cross/Red Crescent, University of Oxford and University of Reading to help stakeholders understand the role of weather event attribution in the decision making process. The game has already been played successfully at a number of high profile events including COP 19 and the African Climate Conference. It has also been used with students as part of a postgraduate environmental management course. As well as describing the design principles of the

  16. 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.

  17. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

    Science.gov (United States)

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

  18. 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

  19. Effects of a La Niña event on hydrological patterns and copepod community structure in a shallow tropical estuary (Taperaçu, Northern Brazil)

    Science.gov (United States)

    Andrade, Marcela P.; Magalhães, André; Pereira, Luci C. C.; Flores-Montes, Manuel J.; Pardal, Emarielle C.; Andrade, Thamara P.; Costa, Rauquírio M.

    2016-12-01

    The influences of the 2011 La Niña event on the hydrological patterns and copepod community structure were investigated in a shallow tropical estuary, the Taperaçu, in northern Brazil. Specifically, this study aimed to explore the response of the most dominant copepod species and ecological indices (diversity, evenness and richness) to temporal changes in rainfall regime and water parameters in a tropical meso-macro tidal setting. Zooplankton samples were collected from three sampling sites using a conical plankton net (120 μm mesh), with both water and zooplankton samples analyzed by standard methods. In 2011, the physical, chemical and biological parameters of the water were exacerbated by increased rainfall levels resulting from the La Niña event. This resulted in a reduction in the salinity and an increase in dissolved nutrient concentrations and phytoplankton biomass in the study area. These conditions had a direct effect on the monthly dynamics of copepods as a whole, and in particular of five species, O. oswaldocruzi (169,090 ± 254,609 ind. m- 3; p 0.05), O. hebes (40,888 ± 64,893 ind. m- 3; p 0.05), all of which were represented by higher densities in February. An extremely high recruitment rate of copepod nauplii was also observed during this month (3,088,309 ± 5,206,645 ind. m- 3; p copepod community, but may also have provoked shifts in trophic dynamics at higher levels, such as zooplanktivorous fishes.

  20. Land use/cover changes, extreme events and ecohydrological responses in the Himalayan region

    Science.gov (United States)

    Singh, R. B.

    1998-10-01

    Land use describes human activities on the earth, and forms a major element of the terrestrial ecosystem modified by humans in the Himalayan region, where developmental activities are increasing rapidly to support the tourism infrastructure. The unprecedented growth in population is putting extremely high pressure on the limited land available for cultivation. Land use and agricultural practices have undergone drastic changes since the mid-1960s through the introduction of development programmes and the application of various newly developed techniques in agrosciences. An analysis of the land use as it has occurred over the last 70 years suggests that it and property rights in the Upper Beas Basin are complex and dynamic. For example, people are giving importance to orchards because of their high profitability. Thus, some agricultural land has been encroached on by orchards. In addition, wastelands are now being used by people for orchards, agriculture and residential and commercial building. Since the Upper Beas River Basin is mountainous, it is fragile and prone to processes like soil erosion, slope instability, landslides and floods. Risks from natural hazards are increasing. However, the state of ecohydrological responses highlight that human-induced ecological changes can be largely proved at the microwatershed level. The findings are not extended to the Himalayan scale. There is also an uncertain correlation between anthropogenic activities (deforestation) in the mountains and hazards in the plains such as floods. Owing to a lack of basic research, there is little effective information which cannot be used for long-term effective monitoring of ecological and hydrological responses to global change. Such an uncertain situation calls for integrated watershed management and development using geographical information systems (GISs).

  1. Landslides in West Coast Metropolitan Areas: The Role of Extreme Weather Events

    Science.gov (United States)

    Biasutti, Michela; Seager, Richard; Kirschbaum, Dalia B.

    2016-01-01

    Rainfall-induced landslides represent a pervasive issue in areas where extreme rainfall intersects complex terrain. A farsighted management of landslide risk requires assessing how landslide hazard will change in coming decades and thus requires, inter alia, that we understand what rainfall events are most likely to trigger landslides and how global warming will affect the frequency of such weather events. We take advantage of 9 years of landslide occurrence data compiled by collating Google news reports and of a high-resolution satellite-based daily rainfall data to investigate what weather triggers landslide along the West Coast US. We show that, while this landslide compilation cannot provide consistent and widespread monitoring everywhere, it captures enough of the events in the major urban areas that it can be used to identify the relevant relationships between landslides and rainfall events in Puget Sound, the Bay Area, and greater Los Angeles. In all these regions, days that recorded landslides have rainfall distributions that are skewed away from dry and low-rainfall accumulations and towards heavy intensities. However, large daily accumulation is the main driver of enhanced hazard of landslides only in Puget Sound. There, landslide are often clustered in space and time and major events are primarily driven by synoptic scale variability, namely "atmospheric rivers" of high humidity air hitting anywhere along the West Coast, and the interaction of frontal system with the coastal orography. The relationship between landslide occurrences and daily rainfall is less robust in California, where antecedent precipitation (in the case of the Bay area) and the peak intensity of localized downpours at sub-daily time scales (in the case of Los Angeles) are key factors not captured by the same-day accumulations. Accordingly, we suggest that the assessment of future changes in landslide hazard for the entire the West Coast requires consideration of future changes in the

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    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 performing long term simulations - using a sewer flow simulation model - and draw up extreme event statistics from the model simulations. In this context it is important to realize that uncertainties related to the input parameters of rainfall runoff models will give rise to uncertainties related...

  3. A twenty-first century California observing network for monitoring extreme weather events

    Science.gov (United States)

    White, A.B.; Anderson, M.L.; Dettinger, M.D.; Ralph, F.M.; Hinojosa, A.; Cayan, D.R.; Hartman, R.K.; Reynolds, D.W.; Johnson, L.E.; Schneider, T.L.; Cifelli, R.; Toth, Z.; Gutman, S.I.; King, C.W.; Gehrke, F.; Johnston, P.E.; Walls, C.; Mann, Dorte; Gottas, D.J.; Coleman, T.

    2013-01-01

    During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. In order to improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, is required. Here we describe how California is addressing their most important and costliest environmental issue – water managem