WorldWideScience

Sample records for extratropical cyclone system

  1. The kinetic and available potential energy budget of a winter extratropical cyclone system

    OpenAIRE

    SMITH, PHILLIP J.; DARE, PATRICIA M.

    2011-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period 9–11 January 1975 is presented. The objectives of the study are (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux...

  2. A comparison of observed and model energy balance for an extratropical cyclone system

    Science.gov (United States)

    Dare, P. M.; Smith, P. J.

    1984-01-01

    Eddy kinetic energy budgets are presented for both moist and dry 48 h forecasts and corresponding observations of a developing winter extratropical cyclone. A diagnosis of observational data energetics is presented and compared with model results for an intense, occluding winter cyclone associated with a strong, well-developed jet stream. The nature of the eddy kinetic energy sources and sinks associated with the strong baroclinic development occurring in this cyclonic system is examined, and the extent to which to observed energy sources and sinks are present in the numerical predictions is addressed. The possibility of explaining differences between the observed and predicted cyclone systems by analyzing these kinetic energy properties is considered.

  3. The kinetic and available potential energy budget of a winter extratropical cyclone system

    Science.gov (United States)

    Smith, P. J.; Dare, P. M.

    1986-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period January 9-11, 1975 is presented. The objectives of the study are: (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux convergence of K, while A increases are due to generation by LHR and K to A conversion. In addition, the general A increase is accompanied by a 24 h oscillation that is explained largely by the flux quantity in the A budget equation and is correlated with a similar fluctuation in the K to A conversion. LHR does not appear to be critical in the development of this cyclone system. Rather, LHR acts to increase the intensity of the event. It is hypothesized that the direct influence that LHR had on the deepening cyclone's reduced mass was augmented by an indirect influence, in which pre-existing dry dynamical forcing was enhanced by diabatic heating, thus leading to accelerated cyclone development at a later time.

  4. The kinetic and available potential energy budget of a winter extratropical cyclone system

    Science.gov (United States)

    Smith, P. J.; Dare, P. M.

    1986-01-01

    The energy budget of an extratropical cyclone system which traversed North America and intensified through the period January 9-11, 1975 is presented. The objectives of the study are: (1) to document the complete energy budget of a significant winter cyclone event, and (2) to comment on the significance of latent heat release (LHR) in the cyclone's evolution. Results reveal an overall increase in both kinetic (K) and available potential energy (A). K increases are accounted for by boundary flux convergence of K, while A increases are due to generation by LHR and K to A conversion. In addition, the general A increase is accompanied by a 24 h oscillation that is explained largely by the flux quantity in the A budget equation and is correlated with a similar fluctuation in the K to A conversion. LHR does not appear to be critical in the development of this cyclone system. Rather, LHR acts to increase the intensity of the event. It is hypothesized that the direct influence that LHR had on the deepening cyclone's reduced mass was augmented by an indirect influence, in which pre-existing dry dynamical forcing was enhanced by diabatic heating, thus leading to accelerated cyclone development at a later time.

  5. The diagnosis of a preblocking explosively-developing extratropical cyclone system

    Science.gov (United States)

    Uhl, Mary A.; Smith, Phillip J.; Lupo, Anthony R.; Zwack, Peter

    1992-01-01

    This paper presents the diagnosis of an extratropical cyclone that developed explosively from 18 to 19 January 1979 over the North Atlantic Ocean. The diagnosis applies data obtained from the Goddard Laboratory for Atmospheres FGGE SOP-1 level III-b global analyses on a 4 deg latitude by 5 deg longitude grid to the extended height tendency and the Zwack-Okossi development equations. The cyclone developed initially in response to cyclonic vorticity advection downstream from an upper air through, warm air advection in a strongly baroclinic region, and latent heat release in the cyclone domain. As development continued, thermal advection and latent heat release increased their role in forcing height falls in the cyclone domain, while the influence of vorticity advection decreased. Finally, development ceased when anticyclonic vorticity advection below 700 mb and adiabatic cooling in the ascending air combined to neutralize the influence of warm air advection and latent heat release.

  6. Objectively classifying Southern Hemisphere extratropical cyclones

    Science.gov (United States)

    Catto, Jennifer

    2016-04-01

    There has been a long tradition in attempting to separate extratropical cyclones into different classes depending on their cloud signatures, airflows, synoptic precursors, or upper-level flow features. Depending on these features, the cyclones may have different impacts, for example in their precipitation intensity. It is important, therefore, to understand how the distribution of different cyclone classes may change in the future. Many of the previous classifications have been performed manually. In order to be able to evaluate climate models and understand how extratropical cyclones might change in the future, we need to be able to use an automated method to classify cyclones. Extratropical cyclones have been identified in the Southern Hemisphere from the ERA-Interim reanalysis dataset with a commonly used identification and tracking algorithm that employs 850 hPa relative vorticity. A clustering method applied to large-scale fields from ERA-Interim at the time of cyclone genesis (when the cyclone is first detected), has been used to objectively classify identified cyclones. The results are compared to the manual classification of Sinclair and Revell (2000) and the four objectively identified classes shown in this presentation are found to match well. The relative importance of diabatic heating in the clusters is investigated, as well as the differing precipitation characteristics. The success of the objective classification shows its utility in climate model evaluation and climate change studies.

  7. The influence of an atmospheric Two-Way coupled model system on the predictability of extratropical cyclones

    Science.gov (United States)

    Schuster, Mareike; Thürkow, Markus; Weiher, Stefan; Kirchner, Ingo; Ulbrich, Uwe; Will, Andreas

    2016-04-01

    A general bias of global atmosphere ocean models, and also of the MPI-ESM, is an under-representation of the high latitude cyclone activity and an overestimation of the mid latitude cyclone activity in the North Atlantic, thus representing the extra-tropical storm track too zonal. We will show, that this effect can be antagonized by applying an atmospheric Two-Way Coupling (TWC). In this study we present a newly developed Two-Way Coupled model system, which is based on the MPI-ESM, and show that it is able to capture the mean storm track location more accurate. It also influences the sub-decadal deterministic predictability of extra-tropical cyclones and shows significantly enhanced skill compared to the "uncoupled" MPI-ESM standalone system. This study evaluates a set of hindcast experiments performed with said Two-Way Coupled model system. The regional model COSMO CLM is Two-Way Coupled to the atmosphere of the global Max-Plack-Institute Earth System Model (MPI-ESM) and therefore integrates and exchanges the state of the atmosphere every 10 minutes (MPI-TWC-ESM). In the coupled source region (North Atlantic), mesoscale processes which are relevant for the formation and early-stage development of cyclones are expected to be better represented, and therefore influence the large scale dynamics of the target region (Europe). The database covers 102 "uncoupled" years and 102 Two-Way Coupled years of the recent climate (1960-2010). Results are validated against the ERA-Interim reanalysis. Besides the climatological point of view, the design of this single model ensemble allows for an analysis of the predictability of the first and second leadyears of the hindcasts. As a first step to understand the improved predictability of cyclones, we will show a detailed analysis of climatologies for specific cyclone categories, sorted by season and region. Especially for cyclones affecting Europe, the TWC is capable to counteract the AOGCM's biases in the North Atlantic. Also

  8. Synoptic and climatological aspects of extra-tropical cyclones

    Science.gov (United States)

    Leckebusch, G. C.

    2010-09-01

    Mid-latitude cyclones are highly complex dynamical features embedded in the general atmospheric circulation of the extra-tropics. Although the basic mechanisms leading to the formation of cyclones are commonly understood, the specific conditions and physical reasons triggering extreme, partly explosive development, are still under investigation. This includes also the identification of processes which might modulate the frequency and intensity of cyclone systems on time scales from days to centennials. This overview presentation will thus focus on three main topics: Firstly, the dynamic-synoptic structures of cyclones, the possibility to objectively identify cyclones and wind storms, and actual statistical properties of cyclone occurrence under recent climate conditions are addressed. In a second part, aspects of the interannual variability and its causing mechanisms are related to the seasonal predictability of extreme cyclones producing severe storm events. Extending the time frame will mean to deduce information on decadal or even centennial time periods. Thus, actual work to decadal as well as climatological variability and changes will be presented. In the last part of the talk focus will be laid on potential socio-economical impacts of changed cyclone occurrence. By means of global and regional climate modeling, future damages in terms of insured losses will be investigated and measures of uncertainty estimated from a multi-model ensemble analysis will be presented.

  9. Variations in Extratropical Cyclone Activity in Northern East Asia

    Institute of Scientific and Technical Information of China (English)

    WANG Xinmin; ZHAI Panmao; WANG Cuicui

    2009-01-01

    Based on an improved objective cyclone detection and tracking algorithm, decadal variations in extratropical cyclones in northern East Asia are studied by using the ECMWF 40 Year Reanalysis (ERA-40) sea-level pressure data during 1958-2001. The results reveal that extratropical cyclone activity has displayed clear seasonal, interannual, and decadal variability in northern East Asia. Spring is the season when cyclones occur most frequently. The spatial distribution of extratropical cyclones shows that cyclones occur mainly within the 40°-50°N latitudinal band in northern East Asia, and the most frequent region of occurrence is in Mongolia. Furthermore, this study also reveals the fact that the frequency of extratropical cyclones has significantly decreased in the lower latitude region of northern East Asia during 1958-2001, but dccadal variability has dominated in higher latitude bands, with frequent cyclone genesis. The intensity of extratropical cyclones has decreased on an annual and seasonal basis. Variation of the annual number of cyclones in northern East Asia is associated with the mean intensity of the baroclinic frontal zone, which is influenced by climate warming in the higher latitudes. Moreover, the dipole structure of extratopical cyclone change, with increases in the north and decreases in the southern part of northern East Asia, is related to the northward movement of the baroclinic frontal zone on either side of 110°E.

  10. Extratropical cyclone classification and its use in climate studies

    Science.gov (United States)

    Catto, J. L.

    2016-06-01

    Extratropical cyclones have long been known to be important for midlatitude weather. It is therefore important that our current state-of-the-art climate models are able to realistically represent these features, in order that we can have confidence in how they are projected to change in a warming climate. Despite the observation that these cyclones are extremely variable in their structure and features, there have, over the years, been numerous attempts to classify or group them. Such classifications can provide insight into the different cloud structures, airflows, and dynamical forcing mechanisms within the different cyclone types. This review collects and details as many classification techniques as possible, and may therefore act as a reference guide to classifications. These classifications offer the opportunity to improve the way extratropical cyclone evaluation in climate models is currently done by giving more insight into the dynamical and physical processes that occur in climate models (rather than just evaluating the mean state over a broad region as is often done). Examples of where these ideas have been used, or could be used, are reviewed. Finally, the potential impacts of future climate changes on extratropical cyclones are detailed. The ways in which the classification techniques could improve our understanding of future changes in extratropical cyclones and their impacts are given.

  11. On the Relationship between Tropical Moisture Exports and Extratropical Cyclones

    Science.gov (United States)

    Knippertz, Peter; Wernli, Heini; Gläser, Gregor; Boleti, Eirini; Joos, Hanna; Binder, Hanin

    2016-04-01

    Tropical moisture export (TME) events are an important element of the global circulation and contribute significantly to regional precipitation. They are defined here on the basis of trajectories starting in the tropical troposphere and reaching a water vapor flux of at least 100 g kg-1 m s-1 poleward of 35° latitude. TME frequency shows four marked occurrence maxima in both hemispheres with varying seasonal cycles. In some cases TMEs can be linked to similar phenomena of atmospheric flow such as Warm Conveyor Belts (WCBs) or Atmospheric Rivers (ARs). For example, 90% of all ARs affecting the US West Coast during December-May are connected to TME events, but the tropical moisture source is less important during the more active AR season June-November. In addition to these climatological TME characteristics we discuss two aspects of their relationship to extratropical cyclones: Case studies indicate that (i) cyclones traveling along the southern fringes of the midlatitude storm track can instigate the export of tropical moisture ahead of their cold fronts, and (ii) the tropical moisture can fuel latent heat release in the cyclone and therefore contribute to its intensification. A long-term statistical analysis of passages of TME trajectories through areas with closed isobars surrounding active cyclones in the northern hemisphere reveals a surprisingly small number of encounters, particularly in winter. The majority of hits occur south of 40°N and there is no statistically significant relationship with cyclone intensification. The results suggest that TMEs often pass relatively far from cyclone centers where vertical motions tend to be moderate. This prevents an early rainout of the tropical moisture and allows the export into higher latitudes. For the same reasons we expect TMEs to "avoid" WCBs with roots at low latitudes. This interpretation is consistent with the fact that most TME maxima are located along the western flanks of subtropical high-pressure systems.

  12. A Multivariate Analysis of Extratropical Cyclone Environmental Sensitivity

    Science.gov (United States)

    Tierney, G.; Posselt, D. J.; Booth, J. F.

    2015-12-01

    The implications of a changing climate system include more than a simple temperature increase. A changing climate also modifies atmospheric conditions responsible for shaping the genesis and evolution of atmospheric circulations. In the mid-latitudes, the effects of climate change on extratropical cyclones (ETCs) can be expressed through changes in bulk temperature, horizontal and vertical temperature gradients (leading to changes in mean state winds) as well as atmospheric moisture content. Understanding how these changes impact ETC evolution and dynamics will help to inform climate mitigation and adaptation strategies, and allow for better informed weather emergency planning. However, our understanding is complicated by the complex interplay between a variety of environmental influences, and their potentially opposing effects on extratropical cyclone strength. Attempting to untangle competing influences from a theoretical or observational standpoint is complicated by nonlinear responses to environmental perturbations and a lack of data. As such, numerical models can serve as a useful tool for examining this complex issue. We present results from an analysis framework that combines the computational power of idealized modeling with the statistical robustness of multivariate sensitivity analysis. We first establish control variables, such as baroclinicity, bulk temperature, and moisture content, and specify a range of values that simulate possible changes in a future climate. The Weather Research and Forecasting (WRF) model serves as the link between changes in climate state and ETC relevant outcomes. A diverse set of output metrics (e.g., sea level pressure, average precipitation rates, eddy kinetic energy, and latent heat release) facilitates examination of storm dynamics, thermodynamic properties, and hydrologic cycles. Exploration of the multivariate sensitivity of ETCs to changes in control parameters space is performed via an ensemble of WRF runs coupled with

  13. Multiple Satellite Observations of Cloud Cover in Extratropical Cyclones

    Science.gov (United States)

    Naud, Catherine M.; Booth, James F.; Posselt, Derek J.; van den Heever, Susan C.

    2013-01-01

    Using cloud observations from NASA Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and CloudSat-CALIPSO, composites of cloud fraction in southern and northern hemisphere extratropical cyclones are obtained for cold and warm seasons between 2006 and 2010, to assess differences between these three data sets, and between summer and winter cyclones. In both hemispheres and seasons, over the open ocean, the cyclone-centered cloud fraction composites agree within 5% across the three data sets, but behind the cold fronts, or over sea ice and land, the differences are much larger. To supplement the data set comparison and learn more about the cyclones, we also examine the differences in cloud fraction between cold and warm season for each data set. The difference in cloud fraction between cold and warm season southern hemisphere cyclones is small for all three data sets, but of the same order of magnitude as the differences between the data sets. The cold-warm season contrast in northern hemisphere cyclone cloud fractions is similar for all three data sets: in the warm sector, the cold season cloud fractions are lower close to the low, but larger on the equator edge than their warm season counterparts. This seasonal contrast in cloud fraction within the cyclones warm sector seems to be related to the seasonal differences in moisture flux within the cyclones. Our analysis suggests that the three different data sets can all be used confidently when studying the warm sector and warm frontal zone of extratropical cyclones but caution should be exerted when studying clouds in the cold sector.

  14. CYGNSS Observations of Surface Wind Speeds in Oceanic Tropical and Extratropical Cyclones

    Science.gov (United States)

    Posselt, D. J.; Crespo, J.; Naud, C. M.

    2016-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) mission is the first of the new generation of NASA Earth Venture missions, and consists of a constellation of eight small satellites scheduled for launch in November 2016. The mission utilizes GPS signals reflected from the Earth's surface to infer near-surface wind speeds over the global tropical oceans. The eight-satellite constellation will observe ocean-surface wind speeds in all weather conditions (including in heavy precipitation) with a median revisit time of approximately 3 hours. While CYGNSS is designed to measure wind speeds in the inner core of tropical cyclones, it will observe near-surface winds over all oceanic regions within the span of its orbit. The orbit inclination is 35 degrees, which means that the satellite will observe primarily the tropics and sub-tropics; however, because the antennae are angled 28 degrees off-nadir, the effective range of latitudes spans -40 to 40 degrees. As such, CYGNSS will observe regions known to be characterized by rapid extratropical cyclone development (e.g., the southern portion of the Gulf Stream off the U.S. East Coast). In this presentation, we discuss CYGNSS sampling characteristics, with an eye toward its potential to observe winds not only in tropical cyclones, but in extratropical cyclones as well. We simulate orbits over a historical extratropical storm, and also utilize a multi-year database of cyclone centers to determine CYGNSS sampling characteristics integrated over many storms.

  15. A link between high-speed solar wind streams and explosive extratropical cyclones

    Science.gov (United States)

    Prikryl, Paul; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Bruntz, Robert

    2016-11-01

    A link between solar wind magnetic sector boundary (heliospheric current sheet) crossings by the Earth and the upper-level tropospheric vorticity was discovered in the 1970s. These results have been later confirmed but the proposed mechanisms remain controversial. Extratropical-cyclone tracks obtained from two meteorological reanalysis datasets are used in superposed epoch analysis of time series of solar wind plasma parameters and green coronal emission line intensity. The time series are keyed to times of maximum growth of explosively developing extratropical cyclones in the winter season. The new statistical evidence corroborates the previously published results (Prikryl et al., 2009). This evidence shows that explosive extratropical cyclones tend to occur after arrivals of solar wind disturbances such as high-speed solar wind streams from coronal holes when large amplitude magneto-hydrodynamic waves couple to the magnetosphere-ionosphere system. These MHD waves modulate Joule heating and/or Lorentz forcing of the high-latitude thermosphere generating medium-scale atmospheric gravity waves that propagate energy upward and downward from auroral zone through the atmosphere. At the tropospheric level, in spite of significantly reduced amplitudes, these gravity waves can provide a lift of unstable air to release the moist symmetric instability thus initiating slantwise convection and forming cloud/precipitation bands. The release of latent heat is known to provide energy for rapid development and intensification of extratropical cyclones.

  16. A diagnosis of the explosive development of two extratropical cyclones

    Science.gov (United States)

    Lupo, Anthony R.; Smith, Phillip J.; Zwack, Peter

    1992-01-01

    This paper examines the 24-h explosive development periods of two extratropical cyclones, the first occurring over the Gulf Stream off the coast of New England from 18 to 19 January 1979 and the second occurring over the southeastern United States from 20 to 21 January 1979. The data used in this study are the First GARP (Global Atmospheric Research Program) Global Experiment (FGGE) level IIIb (SOP I) global analyses on a 4 deg latitude x 5 deg longitude grid. The parameter used to diagnose development is the geostrophic relative vorticity tendency calculated using an extended form of the Zwack-Okossi development equation. This development equation is similar to the Petterssen-Sutcliffe development equation, but is shown to be more complete by explicitly coupling surface development with forcing at all levels above the surface. Cyclonic-vorticity advection, warm-air advection, and latent heat release act to develop the two cyclones, while adiabatic cooling in the ascending air opposes development. Further, vertical profiles of the development quantities for these two cases reveal that vorticity and temperature advection maximize in the 200-300-mb layer, while the latent heat release maximum is typically below 500 mb.

  17. Impact of horizontal spatial resolution on the derivation of the source receptor relationship—an extra-tropical cyclone case

    Science.gov (United States)

    Lee, Jae-Bum; Lee, Tae-Young

    2004-11-01

    A numerical study has been made to evaluate the impact of horizontal resolution on the estimation of the source receptor (S R) relationship. Numerical experiments with four different horizontal grid sizes have been performed for an extra-tropical cyclonic episode in East Asia. CSU RAMS and YU-SADM (Yonsei University's sulfuric acid deposition model) have been used to simulate meteorological and pollutant fields, respectively.In this study, enhanced spatial resolution has improved the simulation of an extra-tropical cyclone, cold front and associated precipitation systems. As spatial resolution increases, the circulation associated with the cyclone and cold front becomes stronger, and the amount of frontal rainfall increases. This study has shown that enhancement of spatial resolution tends to increase self-contributions but decrease foreign contributions to the wet deposition associated with an extra-tropical cyclone. It has been found that increased precipitation for enhanced spatial resolution reduces the amount of transported pollutant but increases the wet deposition of locally emitted pollutants. The larger self-contribution for higher resolutions may also be partially due to the increased strength of resolved convection. The impact of enhancing spatial resolution on dry deposition is felt mostly over downstream regions where the centres of the lows and fronts pass. Contributions from upstream sources increase as cyclonic circulation becomes stronger with increasing spatial resolution. On the other hand, enhancing spatial resolution does not significantly affect the S R relationship for either dry or wet deposition in the other regions where the extra-tropical cyclone does not pass. This study indicates that improved simulation of a cold front does not significantly affect the S R relationship for wet deposition over the area of passage of the cold front. An additional discussion infers a S R relationship for the wet deposition associated with a typical extra-tropical

  18. Kelvin-Helmholtz waves in extratropical cyclones passing over mountain ranges: KH Waves in Extratropical Cyclones over Mountain Ranges

    Energy Technology Data Exchange (ETDEWEB)

    Medina, Socorro [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences; Houze, Robert A. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences; Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-02-19

    Kelvin–Helmholtz billows with horizontal scales of 3–4 km have been observed in midlatitude cyclones moving over the Italian Alps and the Oregon Cascades when the atmosphere was mostly statically stable with high amounts of shear and Ri < 0.25. In one case, data from a mobile radar located within a windward facing valley documented a layer in which the shear between down-valley flow below 1.2 km and strong upslope cross-barrier flow above was large. Several episodes of Kelvin–Helmholtz waves were observed within the shear layer. The occurrence of the waves appears to be related to the strength of the shear: when the shear attained large values, an episode of billows occurred, followed by a sharp decrease in the shear. The occurrence of large values of shear and Kelvin–Helmholtz billows over two different mountain ranges suggests that they may be important features occurring when extratropical cyclones with statically stable flow pass over mountain ranges.

  19. How well do CMIP5 climate models reproduce explosive cyclones in the extratropics of the Northern Hemisphere?

    Science.gov (United States)

    Seiler, C.; Zwiers, F. W.

    2016-02-01

    Extratropical explosive cyclones are rapidly intensifying low pressure systems with severe wind speeds and heavy precipitation, affecting livelihoods and infrastructure primarily in coastal and marine environments. This study evaluates how well the most recent generation of climate models reproduces extratropical explosive cyclones in the Northern Hemisphere for the period 1980-2005. An objective-feature tracking algorithm is used to identify and track cyclones from 25 climate models and three reanalysis products. Model biases are compared to biases in the sea surface temperature (SST) gradient, the polar jet stream, the Eady growth rate, and model resolution. Most models accurately reproduce the spatial distribution of explosive cyclones when compared to reanalysis data ( R = 0.94), with high frequencies along the Kuroshio Current and the Gulf Stream. Three quarters of the models however significantly underpredict explosive cyclone frequencies, by a third on average and by two thirds in the worst case. This frequency bias is significantly correlated with jet stream speed in the inter-model spread ( R ≥ 0.51), which in the Atlantic is correlated with a negative meridional SST gradient ( R = -0.56). The importance of the jet stream versus other variables considered in this study also applies to the interannual variability of explosive cyclone frequency. Furthermore, models with fewer explosive cyclones tend to underpredict the corresponding deepening rates ( R ≥ 0.88). A follow-up study will assess the impacts of climate change on explosive cyclones, and evaluate how model biases presented in this study affect the projections.

  20. A-Train Based Observational Metrics for Model Evaluation in Extratropical Cyclones

    Science.gov (United States)

    Naud, Catherine M.; Booth, James F.; Del Genio, Anthony D.; van den Heever, Susan C.; Posselt, Derek J.

    2015-01-01

    Extratropical cyclones contribute most of the precipitation in the midlatitudes, i.e. up to 70 during winter in the northern hemisphere, and can generate flooding, extreme winds, blizzards and have large socio-economic impacts. As such, it is important that general circulation models (GCMs) accurately represent these systems so their evolution in a warming climate can be understood. However, there are still uncertainties on whether warming will increase their frequency of occurrence, their intensity and how much rain or snow they bring. Part of the issue is that models have trouble representing their strength, but models also have biases in the amount of clouds and precipitation they produce. This is caused by potential issues in various aspects of the models: convection, boundary layer, and cloud scheme to only mention a few. In order to pinpoint which aspects of the models need improvement for a better representation of extratropical cyclone precipitation and cloudiness, we will present A-train based observational metrics: cyclone-centered, warm and cold frontal composites of cloud amount and type, precipitation rate and frequency of occurrence. Using the same method to extract similar fields from the model, we will present an evaluation of the GISS-ModelE2 and the IPSL-LMDZ-5B models, based on their AR5 and more recent versions. The AR5 version of the GISS model underestimates cloud cover in extratropical cyclones while the IPSL AR5 version overestimates it. In addition, we will show how the observed CloudSat-CALIPSO cloud vertical distribution across cold fronts changes with moisture amount and cyclone strength, and test if the two models successfully represent these changes. We will also show how CloudSat-CALIPSO derived cloud type (i.e. convective vs. stratiform) evolves across warm fronts as cyclones age, and again how this is represented in the models. Our third process-based analysis concerns cumulus clouds in the post-cold frontal region and how their

  1. How will climate change affect explosive cyclones in the extratropics of the Northern Hemisphere?

    Science.gov (United States)

    Seiler, C.; Zwiers, F. W.

    2016-06-01

    Explosive cyclones are rapidly intensifying low pressure systems generating severe wind speeds and heavy precipitation primarily in coastal and marine environments. This study presents the first analysis on how explosive cyclones respond to climate change in the extratropics of the Northern Hemisphere. An objective-feature tracking algorithm is used to identify and track cyclones from 23 CMIP5 climate models for the recent past (1981-1999) and future (2081-2099). Explosive cyclones are projected to shift northwards by about 2.2^circ latitude on average in the northern Pacific, with fewer and weaker events south of 45^circ hbox {N}, and more frequent and stronger events north of this latitude. This shift is correlated with a poleward shift of the jet stream in the inter-model spread (R=0.56). In the Atlantic, the total number of explosive cyclones is projected to decrease by about 17 % when averaging across models, with the largest changes occurring along North America's East Coast. This reduction is correlated with a decline in the lower-tropospheric Eady growth rate (R=0.51), and is stronger for models with smaller frequency biases (R=-0.65). The same region is also projected to experience a small intensification of explosive cyclones, with larger vorticity values for models that predict stronger increases in the speed of the jet stream (R=0.58). This strengthening of the jet stream is correlated with an enhanced sea surface temperature gradient in the North Atlantic (R=-0.63). The inverse relationship between model bias and projection, and the role of model resolution are discussed.

  2. The relationship between clouds and dynamics in Southern Hemisphere extratropical cyclones in the real world and a climate model

    Science.gov (United States)

    Govekar, Pallavi D.; Jakob, Christian; Catto, Jennifer

    2014-06-01

    The representation of clouds over the Southern Ocean in contemporary climate models remains a major challenge. A major dynamical influence on the structure of clouds is the passage of extratropical cyclones. They exert significant dynamical influences on the clouds in the dynamically active frontal regions as well as in the dynamically suppressed regions ahead and behind the cyclones. A cyclone compositing methodology is applied to a reanalysis and vertical profiles of cloudiness from CloudSat/CALIPSO to quantify the relationship between clouds and dynamics in extratropical cyclones over the Southern Ocean. It is found that the range of cloud fraction, vertical motion, and relative humidity changes considerably with height. There is a strong quasi-linear relationship between the three variables which changes with altitude. After establishing the observed relationships, the methodology is applied to the Australian Community Climate and Earth System Simulator to evaluate the model's ability to simulate the identified cloud-dynamics relationships. While the model is able to qualitatively reproduce the overall cloud structure, the circulation around the cyclone is generally too weak. As a result, the model fails to represent the observed cloud to dynamics relationship. This wrong relationship in the model leads to a misrepresentation of the cloud field manifested as either an error in the cloud fraction or as simulating the "right" clouds for the "wrong" reason. The result underscores the importance of relationship-oriented model evaluation techniques over simple right or wrong assessments.

  3. Detection of merger and splitting of extra-tropical cyclones

    Science.gov (United States)

    Kew, Sarah; Hanley, John

    2013-04-01

    Results from the project IMILAST (Intercomparison of mid-latitude storm diagnostics) show that, despite a wide variety in the 15 cyclone identification and tracking techniques considered, a reasonable agreement on tracks of intense cyclones can be reached, at least in the central intensifying stage of the cyclone life cycle. In contrast, diagnostics of cyclone genesis and lysis events show reduced agreement amongst the methods with genesis and lysis density maps exhibiting coherence over smaller spatial scales. Recent work by Hanley and Caballero claims that multi-centre cyclones occur more frequently as storm intensity increases, with an associated increase in the probability of spurious splittings by single-centre tracking routines. We investigate whether the methodological differences in handling of cyclone merger and splitting are responsible for the range in genesis/lysis outcomes exhibited in IMILAST results or whether other factors, such as cyclone definition, have more influence over the spread. The study is focussed on a number of selected cases of intense cyclones that undergo a clear merger or splitting. Of the methods contributing to the IMILAST project, three explicitly handle cyclone merger and splitting. In demonstrating the differences between the techniques, we explore what each approach has to offer.

  4. ANALYSIS OF EXTRATROPICAL TRANSITION OF TROPICAL CYCLONE OVER MAINLAND CHINA

    Institute of Scientific and Technical Information of China (English)

    朱佩君; 郑永光; 陶祖钰

    2003-01-01

    Typhoon Winnie (1997) experienced three stages after landfall on China: weakening, transition, and re-intensification. The transition is similar to the "complex transition" model proposed by Matano and Sekioka. During the re-intensification stage, the transformed cyclone developed into a pattern of Shapiro-Keyser Cyclone model. From the diagnosis we can find that the cause of Winnie's transition is the intrusion of cold air from the mid- and upper- troposphere and the warm temperature advection in the lower. Winnie redeveloped after transition,which is the result of three vital factors: the warm temperature advection in the lower troposphere, the divergence on the right side of the upper jet entry and the cyclonic vorticity advection in the upper.

  5. How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble

    Science.gov (United States)

    Yettella, Vineel; Kay, Jennifer E.

    2017-09-01

    The extratropical precipitation response to global warming is investigated within a 30-member initial condition climate model ensemble. As in observations, modeled cyclonic precipitation contributes a large fraction of extratropical precipitation, especially over the ocean and in the winter hemisphere. When compared to present day, the ensemble projects increased cyclone-associated precipitation under twenty-first century business-as-usual greenhouse gas forcing. While the cyclone-associated precipitation response is weaker in the near-future (2016-2035) than in the far-future (2081-2100), both future periods have similar patterns of response. Though cyclone frequency changes are important regionally, most of the increased cyclone-associated precipitation results from increased within-cyclone precipitation. Consistent with this result, cyclone-centric composites show statistically significant precipitation increases in all cyclone sectors. Decomposition into thermodynamic (mean cyclone water vapor path) and dynamic (mean cyclone wind speed) contributions shows that thermodynamics explains 92 and 95% of the near-future and far-future within-cyclone precipitation increases respectively. Surprisingly, the influence of dynamics on future cyclonic precipitation changes is negligible. In addition, the forced response exceeds internal variability in both future time periods. Overall, this work suggests that future cyclonic precipitation changes will result primarily from increased moisture availability in a warmer world, with secondary contributions from changes in cyclone frequency and cyclone dynamics.

  6. How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble

    Science.gov (United States)

    Yettella, Vineel; Kay, Jennifer E.

    2016-10-01

    The extratropical precipitation response to global warming is investigated within a 30-member initial condition climate model ensemble. As in observations, modeled cyclonic precipitation contributes a large fraction of extratropical precipitation, especially over the ocean and in the winter hemisphere. When compared to present day, the ensemble projects increased cyclone-associated precipitation under twenty-first century business-as-usual greenhouse gas forcing. While the cyclone-associated precipitation response is weaker in the near-future (2016-2035) than in the far-future (2081-2100), both future periods have similar patterns of response. Though cyclone frequency changes are important regionally, most of the increased cyclone-associated precipitation results from increased within-cyclone precipitation. Consistent with this result, cyclone-centric composites show statistically significant precipitation increases in all cyclone sectors. Decomposition into thermodynamic (mean cyclone water vapor path) and dynamic (mean cyclone wind speed) contributions shows that thermodynamics explains 92 and 95% of the near-future and far-future within-cyclone precipitation increases respectively. Surprisingly, the influence of dynamics on future cyclonic precipitation changes is negligible. In addition, the forced response exceeds internal variability in both future time periods. Overall, this work suggests that future cyclonic precipitation changes will result primarily from increased moisture availability in a warmer world, with secondary contributions from changes in cyclone frequency and cyclone dynamics.

  7. Hurricane Force Winds in Explosive Maritime Extratropical Cyclones: A Modeling and Observational Study of Their Evolution and Dynamics

    Science.gov (United States)

    Albright, Benjamin Scott

    Extratropical cyclones can be as powerful as tropical cyclones with winds reaching 33 m s-1 or even stronger. They can also be very large in scale, and impact life and property on the oceans as well as over the land if the storms make a landfall. Two conceptual models exist that attempt to explain how the extreme winds in the bent-back frontal zone of these cyclones occur. The first is a jet associated with the cold conveyor belt and the second is through a phenomenon known as a sting jet. Some of the objectives this thesis will address are: (1) The role of gradient wind is during the life-cycle of the cyclone, (2) how model results compare to actual observations, and (3) if the sting jet or cold conveyor belt jet are the only causes for high winds within the bent-back frontal zone, among others. This thesis will examine two case studies of extreme, extratropical cyclones that occurred over the North Atlantic Ocean. Extensive observations including dropsondes, Stepped Frequency Microwave Radiometer (SFMR) measurements from a NOAA WP-3D aircraft and satellite scatterometer measurements are used to compare with modeled results of the two case studies. The Weather Research and Forecasting (WRF) Model Version 3.4.1 and the NOAA Environmental Modeling System (NEMS) NMM-B Launcher are used to model the two case studies and for high resolution and sensitivity testing. Trajectories calculated by the Read/Interpolate/Plot program and cross sections are additional tools used in the study. Some of the major conclusions included identifying sting jets in each storm but they were found not to be the major cause of the highest winds within the bent-back frontal zone. A secondary stream of air that accelerates from the west of the rapidly intensifying cyclone into a low-level jet located within a larger pressure gradient force and thermal gradient was found to be the major source of the high winds. It is suggested that the findings and conclusions based on the results of this

  8. Rossby wave breaking, the upper level jet, and serial clustering of extratropical cyclones in western Europe

    OpenAIRE

    Priestley, Matthew D. K.; Joaquim G. Pinto; Dacre, Helen F.; Shaffrey, Len C.

    2017-01-01

    Winter 2013/14 was the stormiest on record for the UK and was characterized by recurrent clustering of extratropical cyclones. This clustering was associated with a strong, straight and persistent North Atlantic jet and was also associated with Rossby wave breaking (RWB) on both flanks, pinning the jet in place. The occurrence of RWB and cyclone clustering is further studied in 36 years of the ERA-Interim Reanalysis. Clustering at 55°N is associated with an extended and anomalously strong edd...

  9. Extratropical cyclones and the projected decline of winter Mediterranean precipitation in the CMIP5 models

    OpenAIRE

    Zappa, Giuseppe; Hawcroft, Matthew K; Shaffrey, Len; Black, Emily; Brayshaw, David J.

    2015-01-01

    The Mediterranean region has been identified as a climate change "hot-spot" due to a projected reduction in precipitation and fresh water availability which has potentially large socio-economic impacts. To increase confidence in these projections, it is important to physically understand how this precipitation reduction occurs. This study quantifies the impact on winter Mediterranean precipitation due to changes in extratropical cyclones in 17 CMIP5 climate models. In each model, the extratro...

  10. Robustness of serial clustering of extratropical cyclones to the choice of tracking method

    Directory of Open Access Journals (Sweden)

    Joaquim G. Pinto

    2016-07-01

    Full Text Available Cyclone clusters are a frequent synoptic feature in the Euro-Atlantic area. Recent studies have shown that serial clustering of cyclones generally occurs on both flanks and downstream regions of the North Atlantic storm track, while cyclones tend to occur more regulary on the western side of the North Atlantic basin near Newfoundland. This study explores the sensitivity of serial clustering to the choice of cyclone tracking method using cyclone track data from 15 methods derived from ERA-Interim data (1979–2010. Clustering is estimated by the dispersion (ratio of variance to mean of winter [December – February (DJF] cyclone passages near each grid point over the Euro-Atlantic area. The mean number of cyclone counts and their variance are compared between methods, revealing considerable differences, particularly for the latter. Results show that all different tracking methods qualitatively capture similar large-scale spatial patterns of underdispersion and overdispersion over the study region. The quantitative differences can primarily be attributed to the differences in the variance of cyclone counts between the methods. Nevertheless, overdispersion is statistically significant for almost all methods over parts of the eastern North Atlantic and Western Europe, and is therefore considered as a robust feature. The influence of the North Atlantic Oscillation (NAO on cyclone clustering displays a similar pattern for all tracking methods, with one maximum near Iceland and another between the Azores and Iberia. The differences in variance between methods are not related with different sensitivities to the NAO, which can account to over 50% of the clustering in some regions. We conclude that the general features of underdispersion and overdispersion of extratropical cyclones over the North Atlantic and Western Europe are robust to the choice of tracking method. The same is true for the influence of the NAO on cyclone dispersion.

  11. Numerical prediction and potential vorticity diagnosis of extratropical cyclones

    Science.gov (United States)

    Huo, Zonghui

    By combining numerical simulations with different diagnostic tools, this thesis examines the various aspects of two explosively deepening cyclones-the superstorm of March 12-14 1993 and a storm that occurred during the Intensive Observation Period 14 (IOP-14) of the Canadian Atlantic Storm Program (CASP). Using conventional observations, the general aspects of the storms are documented and the dynamical and physical mechanisms are discussed. Then the life cycles are simulated with the Canadian Regional Finite-Element model. To improve the model initial conditions, a methodology is proposed on the basis of potential vorticity thinking, and is tested to be successful in the simulation of the March 1993 superstorm. Using the successful simulations as control runs, a series of numerical sensitivity experiments are conducted to study the impacts of model physics on the development of the two rapidly deepening cyclones. The deepening mechanisms of both storms are examined within the context of PV thinking, i.e., using piecewise potential vorticity inversion diagnostics. In both cases, the upper-level PV anomalies contribute the most to the surface cyclone, followed by the lower-level thermal anomalies and diabatic heating related moist PV anomaly. It is found that a favorable phase tilt between the upper- and lower-level PV anomalies allows a mutual interaction between them, in which the circulations associated with the upper-level anomalies enhance the lower-level anomalies, which in turn feedback positively into the upper-level PV anomalies. In addition to the vertical interactions, there also exist lateral interactions between the upper-level PV anomalies for the March 1993 superstorm. The upper-level PV features (troughs) are isolated with the piecewise PV inversion. By removing or changing the intensity of the trough in the initial conditions, the RFE model is integrated to examine the impact of each trough and its interaction with the other trough on the superstorm

  12. Utilization of satellite cloud information to diagnose the energy state and transformations in extratropical cyclones

    Science.gov (United States)

    Smith, P. J.

    1985-01-01

    An important component of the research was a continuing investigation of the impact of latent release on extratropical cyclone development. Previous efforts to accomplish this task have focused on the energy balance and the vertical motion field of an intense winter extratropical cyclone over the United States. During this fiscal year researchers turned their attention to a more fundamental diagnostic variable, the height tendency. Central to this effort is the use of a modified form of the quasi-geostrophic height tendency equation, in which geostrophic wind components have been replaced by observed winds and a latent heat release term has been added. This methodology was adopted to produce a simple diagnostic model which retains the essential mechanisms of quasi-geostrophic theory but more faithfully describes observed wave development when the Rossby Number approaches and exceeds 0.5. Results to date indicate that the new model yields height tendencies that are superior to those obtained from the quasi-geostrophic formulation and are sufficiently close to the observed tendencies to be a useful tool for diagnosing the principle large-scale forcing mechanisms in th e700-300 mb layer. Of the three forcing terms included in the new model, vortity advection is in general dominant. The most persistent challenge to this dominance is made by the thermal advection. On the whole, latent heat release plays a secondary role. Finally, during the rapid intensification observed for this cyclone, all three processes complement each other in forcing height falls.

  13. Utilization of satellite cloud information to diagnose the energy state and transformations in extratropical cyclones

    Science.gov (United States)

    Smith, P. J.

    1985-01-01

    An important component of the research was a continuing investigation of the impact of latent release on extratropical cyclone development. Previous efforts to accomplish this task have focused on the energy balance and the vertical motion field of an intense winter extratropical cyclone over the United States. During this fiscal year researchers turned their attention to a more fundamental diagnostic variable, the height tendency. Central to this effort is the use of a modified form of the quasi-geostrophic height tendency equation, in which geostrophic wind components have been replaced by observed winds and a latent heat release term has been added. This methodology was adopted to produce a simple diagnostic model which retains the essential mechanisms of quasi-geostrophic theory but more faithfully describes observed wave development when the Rossby Number approaches and exceeds 0.5. Results to date indicate that the new model yields height tendencies that are superior to those obtained from the quasi-geostrophic formulation and are sufficiently close to the observed tendencies to be a useful tool for diagnosing the principle large-scale forcing mechanisms in th e700-300 mb layer. Of the three forcing terms included in the new model, vortity advection is in general dominant. The most persistent challenge to this dominance is made by the thermal advection. On the whole, latent heat release plays a secondary role. Finally, during the rapid intensification observed for this cyclone, all three processes complement each other in forcing height falls.

  14. Characteristic Paths of Extratropical Cyclones that Cause High Wind Events in the Northeast United States

    Science.gov (United States)

    Booth, J. F.; Rieder, H. E.; Lee, D.; Kushnir, Y.

    2014-12-01

    This study analyzes the association between wintertime high wind events (HWEs) in the northeast United States US and extratropical cyclones. Sustained wind maxima in the Daily Summary Data from the National Climatic Data Center's Integrated Surface Database are analyzed for 1979-2012. For each station, a Generalized Pareto Distribution (GPD) is fit to the upper tail of the daily maximum wind speed data, and probabilistic return levels at intervals of 1, 3 and 5-years are derived from the GPD fit. At each interval, wind events meeting the return level criteria are termed HWEs. The HWEs occurring on the same day are grouped into multi-station events allowing the association with extratropical cyclones, which are tracked in the European Center for Medium-Range Weather Forecast ERA-Interim reanalysis. Using hierarchical clustering analysis, this study finds that the HWEs are most often associated with cyclones travelling from southwest to northeast, usually originating west of the Appalachian Mountains. The results show that a storm approaching from the southwest is four times more likely to cause strong surface winds than a Nor'easter. A series of sensitivity analyses confirms the robustness of this result. Next, the relationship between the strength of the wind events and the corresponding storm minimum sea level pressure is analyzed. No robust relationship between these quantities is found for strong wind events. Nevertheless, subsequent analysis shows that a relationship between deeper storms and stronger winds emerges if the analysis is extended to the entire set of wintertime storms.

  15. A Dynamic Analysis and Numerical Simulation of Explosive Development of an Extratropical Cyclone Over Land

    Institute of Scientific and Technical Information of China (English)

    丁一汇; 朱彤

    1994-01-01

    The present paper has made a dynamic and diagnostic study of the process of explosive deepening of an extratropical cyclone over North China on April 25-26, 1983, in order to gain an insight into the physical mechanism of explosive development of cyclone over land. It turns out that this cyclone occurred in the strong baroclinic zone, and the vorticity and thermal advection triggered the initial development of the cyclone. Subsequently, as the rainfall increased, the effect of condensational heating became more and more important. During the time period of rapid intensification (from 1200GMT 25 to 0000GMT 26 April, 1983, the central surface pressure fell down from 998. 2 to 988. 3 hPa), the peak of diabatic heating profile continuously descended, leading to a rapid increase in heating amount in the lower troposphere. This condition is favorable to the explosive development of rotational circulation or vortex. The numerical simulations have further demonstrated the importance of the lowering of heating p

  16. WRF simulations of two extreme snowfall events associated with contrasting extratropical cyclones over the western and central Himalaya

    OpenAIRE

    2015-01-01

    © 2015. American Geophysical Union. All Rights Reserved. Two extreme snowfall events associated with extratropical cyclones, one interacting with the western and one with the central Himalaya, are simulated with the Weather Research and Forecasting (WRF) model over 8 days. One event in January 1999 was driven by a longwave trough over west Asia, with the cyclone becoming terrain-locked in the western Himalayan notch. Another event in March 2006 was driven by a trough further south and east, f...

  17. The relevance of individual microphysical processes for potential vorticity anomalies in extratropical cyclones

    Science.gov (United States)

    Crezee, Bas; Joos, Hanna; Wernli, Heini

    2016-04-01

    Extratropical cyclones have a large impact on daily weather through their accompanying strong winds and precipitation. The latent heating and cooling associated with microphysical processes like condensation, freezing and melting, sublimation and evaporation leads to the formation of distinct cloud diabatic potential vorticity (CDPV) anomalies. Positive low-level CDPV anomalies - which typically are formed along the fronts and close to the cyclone center - have been shown to interact with upper-level PV anomalies thereby potentially enhancing storm intensification. Here a novel method is applied, which calculates backward trajectories from the mature storm stage, integrates cloud diabatic PV changes due to microphysical processes, and constructs a CDPV budget for each individual anomaly. Thereby we quantify the contributions of, e.g., cloud condensation, depositional growth of snow and melting of snow to the individual anomalies and in turn to the near-surface circulation. First, we apply this method to an idealized mid-latitude cyclone. The formation of the relatively small low-level negative CDPV anomalies is dominated each by one specific process, depending on their location relative to the front. For the large positive PV anomaly we find that the strongest contributions are from in-cloud condensation and below-cloud snow melting and rain evaporation. Although contributions of in-cloud depositional growth of ice are rather small, they cover a very large area and are therefore dynamically significant, i.e., they produce a fairly large-scale but low-amplitude anomaly. In addition the results from the idealized simulations are compared to a wintertime cyclone. It will be discussed how well the method works for real cyclones and how closely the results agree with those from the idealized channel model experiment.

  18. Accelerating two-stage explosive development of an extratropical cyclone over the northwestern Pacific Ocean: a piecewise potential vorticity diagnosis

    Directory of Open Access Journals (Sweden)

    Shenming Fu

    2014-03-01

    Full Text Available An extreme explosive extratropical cyclone over the northwestern Pacific Ocean (NPO that formed in winter 2004 and went through two distinct rapid deepening periods was successfully simulated by a non-hydrostatic mesoscale model (MM5. Based on the simulation, the cyclone's rapid deepening was investigated in detail using the piecewise potential vorticity (PV inversion method which successfully captured the characteristics of the cyclone and its associated background circulations. Results indicated that explosive development of the cyclone was dominated by forcings in the extended surface layer (ESL, which were closely related to baroclinity (temperature advection and boundary layer processes (sensible heat exchange. In the interior layer (IL, direct effects of condensation were mainly conducive to the cyclone's development, whereas indirect effects (interactions with other layers mainly acted conversely. Processes associated with latent heat release (LHR were characterised by nonlinearity. Features of the precipitation, including intensity, duration, range and relative configuration to the cyclone determined the influences of condensation on the cyclone. In the upper layer (UL, tropopause-folding processes and horizontal PV advection were main influencing factors to the evolution of the cyclone. Upper-level forcings firstly exerted slight effects on the cyclone's development, since upper-level positive PV anomalies were far from the cyclone; then, as the influencing short-wave trough and the cyclone both moved northeastward, upper-level positive PV anomalies merged, enhanced and entered key areas of the cyclone, and thus both direct and indirect effects associated with the upper-level forcings strengthened significantly around the cyclone, and this dominated the cyclone's transition from a moderate explosive cyclone to an extreme one.

  19. Mesoscale generation of available potential energy in the warm sector of an extratropical cyclone

    Science.gov (United States)

    Fuelberg, H. E.; Ruminski, M. G.; Starr, D. OC.

    1985-01-01

    The generation of available potential energy (APE) was evaluated in the warm sector of an extratropical cyclone containing intense convective activity. Mesoscale rawinsonde data from AVE-SESAME '79 was employed. Parametrization techniques were used for latent and sensible heating components, and variations for the Kuo scheme provided convective latent heat release. Radiative transfer models were used to obtain estimates of infrared and solar processes. The results indicated that solar heating was greater than IR cooling near midday. An extensive low-level cloud deck was the most radiatively active area. Negative generation of APE occurred during most of the period for the SESAME domain as a whole. The leading contributor was convective latent heating located primarily in regions of negative efficiency. Infrared cooling was the only component to consistently produce positive generation. Sensible heating provided an important sink of APE in the low levels during the afternoon.

  20. Effects of Extratropical Cyclone Frequency and Intensity on mass balance of the Greenland Ice Sheet

    Science.gov (United States)

    Auger, J.; Birkel, S. D.; Maasch, K. A.; Mayewski, P. A.

    2014-12-01

    Significant Arctic-wide warming over the past decade is thought to result in part from a weakening of the equator-pole thermal gradient in the atmosphere. Francis and Vavrus (2012) and others link Arctic amplification, or enhanced Arctic warming, to decreasing extratropical cyclone (ETC) speeds, and increasing northward meridional heat transports. Here, we are using the latest high-resolution reanalysis models (ASR, JRA-55, CFSR, ERA-Interim, MERRA) to evaluate how Arctic amplification may be impacting the mass balance of the Greenland Ice Sheet. Our approach is to assess synoptic-scale changes in circulation as represented by changes in storm tracks and storm intensities in the North Atlantic region. As part of this work, we are validating the reanalysis models against existing accumulation, ablation, and meteorological station data available across Greenland, and therefore hope to gain insights on model performance and applicability to the problem domain.

  1. Stratosphere-troposphere exchange in an extratropical cyclone, calculated with a Lagrangian method

    Directory of Open Access Journals (Sweden)

    M. Sigmond

    Full Text Available A Lagrangian technique is developed and applied to calculate stratosphere-troposphere exchange in an extratropical cyclone. This exchange is computed from the potential vorticity or PV along trajectories, calculated from ECMWF circulation data. Special emphasis is put on the statistical significance of the results. The computed field of the cross-tropopause flux is dominated by elongated patterns of statistically significant large downward and small upward fluxes. The downward fluxes mainly occur in the lower part of the considered tropopause folds. The upward fluxes are found near the entrance of the folds, in the tropopause ridges. The ratio between the area averaged downward and upward cross-tropopause fluxes increases with increasing strength of the cyclone. Since the largest fluxes are shown to occur in the regions with the largest wind shear, where PV-mixing is thought to cause large cross-tropopause fluxes, the results are expected to be reliable, at least in a qualitative sense. The position of a tropopause fold along the northwest coast of Africa is confirmed by total ozone observations. The results indicate that the applied Lagrangian technique is an appropriate tool for diagnosing stratosphere-troposphere exchange.

    Key words: Meteorology and atmospheric dynamics (general circulation; mesoscale meteorology; middle atmosphere dynamics

  2. Estudo de caso de ciclone extratropical sobre a América do Sul: sensibilidade das análises Case study of extratropical cyclone over the South America: sensibility of analysis

    Directory of Open Access Journals (Sweden)

    David Mendes

    2009-12-01

    Full Text Available A trajetória e a energética de um ciclone extratropical são analisadas usando as reanálises do NCEP/NCAR, em comparação com as saídas do modelo CPTEC/COLA (T126L28 com análises do GPSAS. A analise da energética e da trajetória de um ciclone, formado no leste da Argentina em 23 de Agosto de 2005, mostrou diferenças significativas entre as reanálises e o modelo, principalmente na sua trajetória e magnitude. A comparação da evolução do ciclone extratropical entre as reanálises e o modelo, mostrou alguns resultados consideráveis, tais como: maior diferença na intensidade da pressão central do ciclone extratropical; maiores diferenças na Energia Cinética após a máxima intensidade do ciclone, e diferenças marcantes no posicionamento do ciclone extratropical.The trajectory and the energetic of extratropical cyclones are analyzed using the NCEP/NCAR reanalysis in comparison with the model outputs CPTEC/COLA (T126L28 with GPSAS analysis. The analysis of the energetic and path of the cyclone formed over East Argentina on 23 August 2005 showed significant differences between the reanalysis and the model, especially in its track and magnitude. The comparison of the extratropical cyclone evolution, between reanalysis and the model, showed some considerable results such as: greater difference in the central pressure intensity of the extratropical cyclones; larger differences in kinetic energy after maximum cyclone intensity and a striking difference in the extratropical cyclone position.

  3. Structural and Environmental Characteristics of Extratropical Cyclones that Cause Tornado Outbreaks in the Warm Sector

    Science.gov (United States)

    Tochimoto, Eigo; Niino, Hiroshi

    2016-04-01

    The differences in structural and environmental characteristics of extratropical cyclones (hereafter, ECs) that cause tornado outbreaks and those that do not were examined through composite analyses of the newly-released Japanese reanalysis data (JRA-55) and idealized numerical experiments. ECs that developed in the United States in April and May between 1995 and 2012 are categorized into two groups: ECs accompanied by 15 or more tornadoes (hereafter, outbreak cyclones (OCs)) and ECs accompanied by 5 or less tornadoes (non-outbreak cyclones (NOCs)). 55 OCs and 41 NOCs that are of similar strength as OCs are selected in this study. The composite analyses show significant differences in convective environmental parameters between OCs and NOCs. For OCs, convective available potential energy (CAPE) and storm relative environmental helicity (SREH) are larger and the areas in which these parameters have significant values are wider in the warm sector. The larger CAPE in OCs is due to larger amount of low-level water vapor, while the larger SREH in OCs due to stronger southerly wind at low levels. A piecewise potential vorticity (PV) diagnostics (Davis and Emanuel, 1991) indicates that low- to mid-level PV anomalies mainly contribute to the difference in the low-level winds between OCs and NOCs. On the other hand, the low-level winds associated with upper-level PV anomalies are not the major contributor to the difference. The results of the idealized numerical experiments for OCs and NOCs (hereafter, referred to as OC-CTL and NOC-CTL, respectively) using WRF ver. 3.4 show that the characteristics of the low-level wind fields and SREH distributions for the simulated ECs in OC-CTL and NOC-CTL are similar to those for OCs and NOCs, respectively. In OC-CTL, SREH and low-level winds in the east-southeast region of the EC center is larger than those in NOC-CTL, respectively. It is suggested that these differences are due to the structures of jetstream. The structure of

  4. Exploring post-cold frontal moisture transport in an idealized extratropical cyclone study

    Science.gov (United States)

    Sheffield, Amanda Marie

    Moisture transport in extratropical cyclones (ETCs) has been studied in the past in the context of the warm conveyor belt (WCB), a 'conveyor belt' transferring moisture from the warm sector boundary layer to the free troposphere both eastward and poleward of the warm front. Recent research has highlighted a different, potentially important mechanism of transporting water vapor in ETCs by post-cold frontal (PCF) clouds. PCF clouds are typically boundary layer cumulus clouds located in the cold sector of an ETC that transfer moisture to the free troposphere through convective-evaporative processes. Recent studies have suggested that these PCF cumuli may vertically transport nearly equivalent amounts of moisture as the WCB. Therefore, not only are these PCF cumuli important in venting the PCF boundary layer, they also play a role in limiting the amount of moisture available for convergence in the source region of the WCB. This limitation can have important consequences for regional weather and climate through its impact on the timing and location of precipitation, the three-dimensional redistribution of water vapor, and the distribution of clouds within ETCs. The goal of this study is to investigate the role of PCF clouds in the moisture transport of an ETC, and the impacts of environmental factors such as SST and aerosol loading on this transport role. We have achieved this goal through the use of numerical simulations of such a storm system. Previous studies have utilized model simulations with relatively coarse grid resolutions and convective parameterization schemes. Here, we simulate a wintertime ETC over the Pacific Ocean using high spatial and temporal resolution, advanced microphysics and explicitly resolved convection. The results of this research demonstrate that PCF cumuli are found to vertically ventilate BL moisture over an expansive region behind the cold front. The free tropospheric moisture contents and stability profile of the cold sector exert a

  5. Objective determination of the extratropical transition of tropical cyclones in the Northern Hemisphere

    Directory of Open Access Journals (Sweden)

    Joshua Studholme

    2015-05-01

    Full Text Available Extratropical transition (ET has eluded objective identification since the realisation of its existence in the 1970s. Recent advances in numerical, computational models have provided data of higher resolution than previously available. In conjunction with this, an objective characterisation of the structure of a storm has now become widely accepted in the literature. Here we present a method of combining these two advances to provide an objective method for defining ET. The approach involves applying K-means clustering to isolate different life-cycle stages of cyclones and then analysing the progression through these stages. This methodology is then tested by applying it to five recent years from the European Centre of Medium-Range Weather Forecasting operational analyses. It is found that this method is able to determine the general characteristics for ET in the Northern Hemisphere. Between 2008 and 2012, 54% (±7, 32 of 59 of Northern Hemisphere tropical storms are estimated to undergo ET. There is great variability across basins and time of year. To fully capture all the instances of ET is necessary to introduce and characterise multiple pathways through transition. Only one of the three transition types needed has been previously well-studied. A brief description of the alternate types of transitions is given, along with illustrative storms, to assist with further study.

  6. The role of the cold sector of extratropical cyclones in setting atmospheric mean state features of the Gulf Stream basin.

    Science.gov (United States)

    Vannière, Benoît; Czaja, Arnaud; Dacre, Helen; Woollings, Tim

    2016-04-01

    The mechanism by which the Gulf Stream SST front anchors a band of precipitation on its warm edge is still a matter of debate and little is known about how synoptic activity contributes to shape precipitation mean state pattern. In this talk, we introduce a new indicator for the cold sector of extratropical storms based on low-level PV. This indicator is used in ERA interim data to separate the cold sector contribution to precipitation and vertical wind from the contribution of the rest of the storm. We find that cold sector precipitation forms a band following the SST front closely. In contrast, the enhanced ascent on the warm edge of the front is set primarily by the warm sector and cannot be directly related to the precipitation band as proposed by previous studies. Numerical sensitivity experiments of an extratropical cyclone passing over different sets of SST further confirms that the anchoring effect of the SST front on precipitation comes exclusively from the cold sector. These results lead us to revisit the atmospheric boundary layer model proposed to describe air-sea interactions over the Gulf-Stream SST gradient. Finally, we explore the role of the cold sector convection in restoring baroclinicity in the wake of an extratropical cyclone.

  7. The influence of solar wind on extratropical cyclones – Part 1: Wilcox effect revisited

    Directory of Open Access Journals (Sweden)

    M. Rybanský

    2009-01-01

    mean VAI response to SBP associated with the north-to-south reversal of BZ is leading by up to 2 days the mean VAI response to SBP associated with the south-to-north reversal of BZ. For the latter, less geoeffective events, the VAI minimum deepens (with the above exception of the Northern Hemisphere low-aerosol 500-mb VAI and the VAI maximum is delayed. The phase shift between the mean VAI responses obtained for these two subsets of SBP events may explain the reduced amplitude of the overall Wilcox effect. In a companion paper, Prikryl et al. (2009 propose a new mechanism to explain the Wilcox effect, namely that solar-wind-generated auroral atmospheric gravity waves (AGWs influence the growth of extratropical cyclones. It is also observed that severe extratropical storms, explosive cyclogenesis and significant sea level pressure deepenings of extratropical storms tend to occur within a few days of the arrival of high-speed solar wind. These observations are discussed in the context of the proposed AGW mechanism as well as the previously suggested atmospheric electrical current (AEC model (Tinsley et al., 1994, which requires the presence of stratospheric aerosols for a significant (Wilcox effect.

  8. A Comparison of Precipitation Distribution of Two Landfalling Tropical Cyclones during the Extratropical Transition

    Institute of Scientific and Technical Information of China (English)

    CHEN Guanghua

    2011-01-01

    The precipitation distributions associated with two landfalling tropical cyclones (TCs) during extratropical transition (ET) were examined in this study.Their distinction is that the bulk of precipitation fell to the left of the TC track in one TC and to the right in the other.The analyses indicate that,for the TC Haima (2004) case,accompanied by the approach of a deep midlatitude trough throughout the depth of the troposphere,the warm and moist air advection by the southeasterly flow north of TC was favorable for warm advection and frontogenesis to the northwest of the TC.Due to the steepening of equivalent potential temperature (θe),the air-parcel uplift along the θe surface,in collaboration with thermally direct circulation related to frontogenesis,led to enhanced precipitation northwest of the TC.In contrast,for TC Matsa (2005)embedded within a moister environment,a weak midlatitude trough was situated at the mid-upper level.The convection was triggered by the conditional instability at the lower level and then sustained by dynamic forcing at the mid-upper level so that the heavy precipitation occurred to the northeast of TC.For the two TC cases,the precipitation enhancement was also linked to the upper-level anomalous divergence associated with the jet-related forcing on the right side of the jet entrance.From the quasigeostrophic perspective,the advection of geostrophic absolute vorticity by the thermal wind most likely served as an indication reflecting the displacement of the vertical motion relative to the center of the TC.

  9. A comparison of observed and numerically predicted eddy kinetic energy budgets for a developing extratropical cyclone

    Science.gov (United States)

    Dare, P. M.; Smith, P. J.

    1983-01-01

    The eddy kinetic energy budget is calculated for a 48-hour forecast of an intense occluding winter cyclone associated with a strong well-developed jet stream. The model output consists of the initialized (1200 GMT January 9, 1975) and the 12, 24, 36, and 48 hour forecast fields from the Drexel/NCAR Limited Area Mesoscale Prediction System (LAMPS) model. The LAMPS forecast compares well with observations for the first 24 hours, but then overdevelops the low-level cyclone while inadequately developing the upper-air wave and jet. Eddy kinetic energy was found to be concentrated in the upper-troposphere with maxima flanking the primary trough. The increases in kinetic energy were found to be due to an excess of the primary source term of kinetic energy content, which is the horizontal flux of eddy kinetic energy over the primary sinks, and the generation and dissipation of eddy kinetic energy.

  10. Diagnosing the Influence of Diabatic Processes on the Explosive Deepening of Extratropical Cyclones over the North Atlantic Ocean

    Science.gov (United States)

    Knippertz, P.; Fink, A. H.; Pohle, S.; Pinto, J. G.

    2012-04-01

    The relative roles of baroclinic and diabatic processes for explosive deepening of extratropical cyclones have been debated for a long time, mostly on the basis of case studies. Here we present a powerful diagnostic approach to the problem, which is based on a combination of an automatic cyclone tracking with a special version of the classical pressure tendency equation (PTE) that relates changes in surface pressure to contributions from horizontal and vertical temperature advection as well as diabatic processes, i.e., mainly latent heat release in clouds. Along the entire track of a cyclone, the PTE is evaluated in a 3°x3° box from the surface to 100 hPa centred on the location the storm is moving to within the next time step. The great advantage of this new approach is the easy applicability to large gridded datasets, even if diabatic tendencies are not explicitly available as in many reanalysis products. The strengths and limitations of the method are illustrated here through application to several explosively deepening, damaging winter storms over the North Atlantic Ocean. Data used are 6-hourly ERA-Interim re-analyses. For better interpretation of the results, the PTE analysis is complemented with other classical cyclogenetic factors, i.e., the strength of the polar jet and the equivalent-potential temperature θe at 850 hPa in the warm sector. The main conclusions from this analysis are: • The time evolutions of the actual core pressure of the storm and the 6-hourly pressure changes in the moving box used to evaluate the PTE show structural similarities that are dominated by the explosive deepening. • The vertical advection term is positive throughout the entire lifecycle of all storms indicating the dominance of ascent downstream of the cyclone center. It is (over-) compensated by negative contributions through warm advection and diabatic heating. • Storms "Martin" and "Kyrill" are dominated by baroclinic processes with contributions of diabatic

  11. A Numerical Study on the Effect of an Extratropical Cyclone on the Evolution of a Midlatitude Front

    Institute of Scientific and Technical Information of China (English)

    CHEN Guanghua

    2013-01-01

    The extratropical transition (ET) of tropical cyclone (TC) Haima (2004) was simulated to understand the impact of TC on midlatitude frontal systems.Two experiments were conducted using the Advanced Research version of the Weather Research and Forecast (WRF) model.In the control run (CTL),a vortex was extracted from the 24-hour pre-run output and then inserted into the National Centers for Environmental Prediction (NCEP) global final (FNL) analysis as an initial condition,while TC circulation was removed from the initial conditions in the sensitivity run (NOTC).Comparisons of the experiments demonstrate that the midlatitude front has a wider meridional extent in the NOTC run than that in the CTL run.Furthermore,the CTL run produces convection suppression to the southern side of the front due to strong cold advection related to the TC circulation.The easterly flow north of the TC not only decelerates the eastward displacement of the front and contracts its zonal scale but also transports more moisture westward and lifts the air along equivalent potential temperature surfaces ahead of the front.As a result,the ascending motion and diabatic heating are enhanced in the northeastern edge of the front,and the anticyclonic outflow in the upper-level is intensified.The increased pressure gradient and divergent flow aloft strengthen the upper-level jet and distort the trough axis in a northwest-southeast orientation.The thermal contrast between the two systems and the dynamic contribution related to the TC circulation can facilitate scalar and rotational frontogenesis to modulate the frontal structure.

  12. Tropical Cyclone Information System

    Science.gov (United States)

    Li, P. Peggy; Knosp, Brian W.; Vu, Quoc A.; Yi, Chao; Hristova-Veleva, Svetla M.

    2009-01-01

    The JPL Tropical Cyclone Infor ma tion System (TCIS) is a Web portal (http://tropicalcyclone.jpl.nasa.gov) that provides researchers with an extensive set of observed hurricane parameters together with large-scale and convection resolving model outputs. It provides a comprehensive set of high-resolution satellite (see figure), airborne, and in-situ observations in both image and data formats. Large-scale datasets depict the surrounding environmental parameters such as SST (Sea Surface Temperature) and aerosol loading. Model outputs and analysis tools are provided to evaluate model performance and compare observations from different platforms. The system pertains to the thermodynamic and microphysical structure of the storm, the air-sea interaction processes, and the larger-scale environment as depicted by ocean heat content and the aerosol loading of the environment. Currently, the TCIS is populated with satellite observations of all tropical cyclones observed globally during 2005. There is a plan to extend the database both forward in time till present as well as backward to 1998. The portal is powered by a MySQL database and an Apache/Tomcat Web server on a Linux system. The interactive graphic user interface is provided by Google Map.

  13. JPL Tropical Cyclone Information System

    Data.gov (United States)

    National Aeronautics and Space Administration — The JPL Tropical Cyclone Information System (TCIS) brings together satellite and in situ data sets from various sources to help you find information for a particular...

  14. The impact of the Arctic Sea Ice retreat on extratropical cyclones and anticyclones over Northern Eurasia: atmospheric model simulations

    Science.gov (United States)

    Akperov, Mirseid; Semenov, Vladimir; Mokhov, Igor; Lupo, Antony

    2015-04-01

    The Arctic region has been warming more than twice as fast as the other parts of the world during the last few decades. The rapid Arctic warming is accompanied with the dramatic change of Arctic sea ice cover. Recently, it has been suggested that such climatic changes might have led to the increase of anomalous weather events in winter over Northern Eurasia. One example is anomalous cold winters over Northern Eurasia associated with atmospheric blocking events. However, a large uncertainty remains concerning robustness of the observed relationship and associated mechanisms of impact. The main goal of this research is to explore the connection between the declining Arctic sea ice (most strongly expressed in the Barents-Kara Seas region) in the cold season and the change of cyclonic and anti-cyclonic activity over Northern Eurasia using simulations with atmospheric general circulation model (AGCM). The simulations were performed with the ECHAM5 AGCM using identical sea surface temperature climatology but different sea ice concentrations (SIC) for the periods corresponding to the high (1966-1969), low (1990-1995) and very low (2005-2012) SIC regimes in the Arctic as well as for the mean climatological SIC for 1971-2000. The duration of each simulation was 50 years. For the regimes with high and very low SIC, a statistically significant increase in the number of long-living anticyclones (with lifetime of more than 5 days) over Northern Eurasia was found. Long-living cyclones exhibited different changes in their number depending on their intensity. The analysis of the spatial patterns of cyclonic and anti-cyclonic activity over Eurasia was performed. We found an increase of the frequency of cyclones over the central region of the European part of Russia (EPR) and anticyclones over the northern region of the EPR for the regimes with a high sea ice concentration in the Arctic. For the regime with very low SIC the shift of the frequency of cyclones and anticyclones towards

  15. Extratropical Weather Systems on Mars: Radiatively-Active Water Ice Effects

    Science.gov (United States)

    Hollingsworth, J. L.; Kahre, M. A.; Haberle, R. M.; Urata, R. A.; Montmessin, F.

    2017-01-01

    Extratropical, large-scale weather disturbances, namely transient, synoptic-period,baroclinic barotropic eddies - or - low- (high-) pressure cyclones (anticyclones), are components fundamental to global circulation patterns for rapidly rotating, differentially heated, shallow atmospheres such as Earth and Mars. Such "wave-like" disturbances that arise via (geophysical) fluid shear instability develop, mature and decay, and travel west-to-east in the middle and high latitudes within terrestrial-like planetary atmospheres. These disturbances serve as critical agents in the transport of heat and momentum between low and high latitudes of the planet. Moreover, they transport trace species within the atmosphere (e.g., water vapor/ice, other aerosols (dust), chemical species, etc). Between early autumn through early spring, middle and high latitudes on Mars exhibit strong equator-to-pole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems [Banfield et al., 2004; Barnes et al., 1993]. A good example of traveling weather systems, frontal wave activity and sequestered dust activity from MGS/MOC image analyses is provided in Figure 1 (cf. Wang et al. [2005]). Utilizing an upgraded and evolving version of the NASA Ames Research Center (ARC) Mars global climate model, investigated here are key dynamical and physical aspects of simulated northern hemisphere (NH) large-scale extratropica lweather systems,with and without radiatively-active water ice clouds. Mars Climate Model:

  16. Cyclone frequency in east asia and double-cyclones

    OpenAIRE

    Umemoto, Tohru

    1982-01-01

    Japanese meteorologists call a certain type of cyclone "Futatsudama-teikiatsu" (Double-cyclone). The relationships between frequencies of extratropical cyclones and Double-cyclones were studied. Using a 2° latitude/longitude grid covering East Asia, three high frequency belts were found. Double-cyclones were classified into three types. Features of occurrence of these three types were discussed.

  17. Tropical-Extratropical Interactions and Intrasasonal Oscillations in the Indian Monsoon System in a Warmer Planet

    Science.gov (United States)

    Carvalho, L. V.; Jones, C.; Cannon, F.; Norris, J.

    2015-12-01

    The India summer monsoon (ISM) experiences long periods of wet and dry conditions frequently associated with floods and long dry spells. These events are largely governed by northward propagating boreal summer monsoon intraseasonal oscillations (MISO). Here we investigate intraseasonal variability of the ISM in the climate of the 20th century using the Climate Forecast System Reanalysis (1979-2013) and examine future scenarios of climate change using models of the Coupled Model Intercomparison Project Phase-5 project. ISM is characterized with a large-scale index obtained by performing combined EOF analysis of precipitation, low level circulation, specific humidity and temperature. This index realistically defines the monsoon's onset and withdrawal, is well correlated with seasonal precipitation in India and exhibits variance on intraseasonal timescales that are related to MISO and extreme wet and dry conditions in India. With similar approach we investigate the skill of the CMIP5 models in realistically simulating MISO in the 'historic' run (1951-2005) and examine projected changes in the amplitude and persistence these events in the high-emission representative concentration pathway 8.5 (RCP8.5) (2006-2100). MISO is well characterized in CMIP5 models that indicate significant increase in the intensity and frequency of extremely dry and wet conditions affecting India by 2050. We show that the main mechanism driving MISO in CMIP5 models are linked to the propagation of extratropical wave trains and interactions with the tropics. In a warmer planet, the increase in polar temperatures weakens the tropical-extratropical temperature gradient and decreases the intensity of the upper tropospheric jet. These changes in the jet and in the baroclinic structure of the atmosphere result in enhanced extratropical wave activity and more extreme events. We use a wave tracking algorithm to demonstrate these differences and explore physical and dynamical mechanisms underlying

  18. Tracking winter extra-tropical cyclones based on their relative vorticity evolution and sensitivity to prior data filtering (cycloTRACK v1.0

    Directory of Open Access Journals (Sweden)

    E. Flaounas

    2014-02-01

    Full Text Available In this study we present a new cyclone identification and tracking algorithm. Identification is based on a recognition pattern of enclosed contours of 850 hPa filtered relative vorticity values, while tracking is based on the minimization of a cost function. In particular, for each tracked cyclone our algorithm builds all possible tracks and finally chooses the one which presents the least differences of relative vorticity between consecutive track points. In parallel, for each track point the algorithm provides a cyclone area within which different physical diagnostics are calculated (such as pressure and wind speed. The area size is a function of the cyclone relative vorticity. To validate our approach we apply the algorithm on the Northern Hemisphere for the winters of 1989–2009. Three integrations of the algorithm were performed, each by using different filtering strengths. Using the three integrations, we assess the algorithm sensitivity to prior filtering the relative vorticity field. We show that filtering the input relative vorticity fields has an impact only on the weak cyclones, while in their majority the strong cyclones are independently detected and tracked.

  19. 北半球温带气旋客观研究方法及模拟和预估的研究进展%A Review of the Research on Objective Method and Simulation and Projection of Extratropical Cyclone over the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇

    2015-01-01

    温带气旋是影响中高纬度地区大范围天气气候变化的重要天气系统之一,研究其气候特征、活动规律和变化趋势对改进天气预报和理解全球气候变化具有重要意义。从主要温带气旋的识别方法、当前气候时期温带气旋的变化、气候情景下未来温带气旋变化的预估以及不确定性分析等4个方面,全面回顾了北半球温带气旋的研究进展:(1)20世纪80年代后,基于再分析数据和大气环流模式(GCM)的发展,温带气旋研究从主观分析开始向客观识别方法发展;(2)再分析和模式数据均显示北半球存在两个温带气旋主活动中心和两个次活动中心,主活动中心分别位于北太平洋和北大西洋地区,次活动中心分别位于地中海和蒙古地区;(3)在人类活动影响的气候变化情景下,大多数模式模拟得到北半球大部分地区温带气旋数目将减少,个别地区的温带气旋数目将增加;(4)由于不同研究中对阈值、物理量和大气层的选取存在差异,这使得对当前气候时期和GCM模拟研究中的温带气旋及其变化和趋势问题还存在许多不确定性。因此,目前亟待解决的问题是对于温带气旋的不同研究方法和研究结果做更多具体的比较分析,从而给出对温带气旋更深入的认识。%Extratropical cyclone is one of the important synoptic systems which affect climate/weather variability over a wide area of mid- and high latitudes, and it is meaningful to research its climatic characteristics, activity patterns, and variation tendency. A comprehensive review of research progress of extratropical cyclones over the Northern Hemisphere from four aspects, involving identiifcation methods, changes during present climate period, changes estimated under the future climate scenarios, and uncertainty analysis of extratropical cyclones, is discussed: (1) In view of the development of

  20. Identification of a subtropical cyclone in the proximity of the Canary Islands and its analysis by numerical modeling

    Science.gov (United States)

    Quitián-Hernández, L.; Martín, M. L.; González-Alemán, J. J.; Santos-Muñoz, D.; Valero, F.

    2016-09-01

    Subtropical cyclones (STC) are low-pressure systems that share tropical and extratropical characteristics. Because of the great economic and social damage, the study of these systems has recently grown. This paper analyzes the cyclone formed in October 2014 near the Canary Islands and diagnoses such a cyclone in order to identify its correspondence to an STC category, examining its dynamical and thermal evolution. Diverse fields have been obtained from three different numerical models, and several diagnostic tools and cyclone phase space diagrams have been used. An extratropical cyclone, in its early stage, experimented a process of cut-off and isolation from the midlatitude flow. The incursion of a trough in conjunction with a low-level baroclinic zone favored the formation of the STC northwestern of the Canary Islands. Streamers of high potential vorticity linked to the cyclone favored strong winds and precipitation in the study domain. Cyclone phase space diagrams are used to complement the synoptic analysis and the satellite images of the cyclone to categorize such system. The diagrams reveal the transition from extratropical cyclone to STC remaining for several days with a subtropical structure with a quite broad action radius. The study of the mesoscale environment parameters showed an enhanced conditional instability through a deep troposphere layer. It is shown that moderate to strong vertical wind shear together with relatively warm sea surface temperature determine conditions enabling the development of long-lived convective structures.

  1. A Subtropical Cyclone in the Canary Islands: the October 2014 event

    Science.gov (United States)

    Quitian, Lara; Martin, Maria Luisa; Jesús González-Alemán, Juan; Santos-Muñoz, Daniel; Valero Rodríguez, Francisco

    2016-04-01

    Depending on the thermal structure and dynamics, there are different types of cyclones in the troposphere. Subtropical cyclones (STC) are low pressure systems that share tropical and extratropical characteristics, having hybrid thermal structures. In October 2014, a cyclonic system landfall the Canary Islands, causing widespread damages. The system began to develop in October 18 and its effects lasted until October 21. Here, the diagnosis and identification of such cyclone as STC is carried out, examining its dynamical and thermal evolution. Diverse fields have been obtained from three different numerical models, and several diagnostic tools and cyclone phase space diagrams have been used. The cyclone evolved from a typical extratropical cyclone, detached from the atmospheric circulation which was highly meridional and became a stationary cut-off low. The meridional intrusion of the trough as well as a low-level baroclinic zone favored the formation of a STC northwestern of the Canary Islands. Several cyclone phase space diagrams are used to classify the cyclone as a STC, highlighting a deep cold core in its early stages that develops into a shallow warm core. High potential vorticity areas associated with the cyclone promoted strong winds and precipitation over the Islands. Throughout the event, an increased conditional instability is observed in the different soundings, leading to strong vertical wind shear. Moreover, relatively warm sea surface temperature is obtained, establishing the conditions to favor the organization of long-lived convective structures.

  2. Tropical Cyclone Signatures in Atmospheric Convective Available Potential Energy

    Science.gov (United States)

    Studholme, Joshua; Gulev, Sergey

    2016-04-01

    Tropical cyclones play an important role in the climate system providing transports of energy and water vapor, forcing the ocean, and also affecting mid-latitude circulation phenomena. Tropical cyclone tracks experience strong interannual variability and in addition, longer term trend-like changes in all ocean basins. Analysis of recent historical data reveal a poleward shift in the locations of tropical cyclone tracks in both the Northern and Southern Hemispheres (Kossin et al. 2014, Nature, 509, 349-352). The physical consequences of these alterations are largely unconstrained. For example, the increasing encroachment of tropical cyclone activity into the extra-tropical environment presents a novel and still poorly understood paradigm for tropical-extratropical interactions. In this respect, the role that the atmospheric convective available potential energy (CAPE) plays in the dynamics of tropical cyclones is highly interesting. The two characteristic global-scale spatial patterns in CAPE are identified using EOF analysis. The first pattern shows an abundance of CAPE in the centre of the Pacific and corresponds to the El Nino Southern Oscillation. The second one is capturing positive CAPE anomalies in the oceanic tropics and negative anomalies over equatorial Africa. Associated with these buoyancy patterns, alterations in tropical cyclone activity occur in all basins forming both zonal and meridional patterns. Atmospheric buoyancy is the trigger for deep convection, and subsequently cyclone genesis. This is the mechanism of impact upon location at the start of cyclone tracks. It is found to have less impact upon where cyclones subsequently move, whether or not they undergo extratropical transition and when and where they experience lysis. It is shown that CAPE plays a critical role in the general circulation in the tropics which in turn is the larger steering context for embedded systems within the Walker and Hadley cells. So this lack of `latter life' impact

  3. Diagnostic analysis of the extratropical re-intensification of tropical cyclones over mainland of China%中国大陆上变性加强热带气旋的诊断分析

    Institute of Scientific and Technical Information of China (English)

    李侃; 徐海明

    2011-01-01

    Based on the Tropical Cyclone (TC) Yearbook's data of JMA from 1979 to 2007, statistical analyses were performed to study the extratropical transition ( ET) of tropical cyclones over mainland of China. Results indicated that there were 16 tropical cyclones over the mainland of China, which accounted for 8. 56% of the total number of tropical cyclones that made landfall on China during the 29 a, only 8 of these ET cases got strengthened after transition. In addition, the moist potential vorticity ( MPV ) and the dynamic, thermodynamic processes analyses of the 8 ET cases're-intensification revealed that the combination of the dynamic and thermodynamic processes was able to define a development region in which it was favorable for intensification of most ET cases over mainland of China during the 29 a. Moreover, the upper-level positive MPV propagated downward to low-level during the obvious re-intensification phase of ET, however, the upper-level positive MPV did not always propagate downward when the ET of TC was reinforced only a little.%利用1979-2007年日本气象厅热带气旋年鉴资料,对在中国大陆上发生变性的热带气旋进行了统计分析,结果表明:29 a间中国大陆上发生变性的热带气旋共有16个,占登陆中国热带气旋总数的8.56%,其中8个变性后加强.利用日本JRA-25再分析资料诊断分析了这8个变性加强热带气旋的湿位涡垂直分布特征以及影响热带气旋变性发展的热力、动力因子,结果表明:29 a间中国大陆上大部分变性热带气旋的再加强均与中高层动力因子和低层热力因子所组成的发展区密切相关;变性加强明显的热带气旋,其高层的正湿位涡下传至低层,而变性加强幅度较小的热带气旋,其高层正湿位涡并不一定会下传至低层.

  4. Forecasting of cyclone Viyaru and Phailin by NWP-based cyclone prediction system (CPS) of IMD – an evaluation

    Indian Academy of Sciences (India)

    S D Kotal; S K Bhattacharya; S K Roy Bhowmik; P K Kundu

    2014-10-01

    An objective NWP-based cyclone prediction system (CPS) was implemented for the operational cyclone forecasting work over the Indian seas. The method comprises of five forecast components, namely (a) Cyclone Genesis Potential Parameter (GPP), (b) Multi-Model Ensemble (MME) technique for cyclone track prediction, (c) cyclone intensity prediction, (d) rapid intensification, and (e) predicting decaying intensity after the landfall. GPP is derived based on dynamical and thermodynamical parameters from the model output of IMD operational Global Forecast System. The MME technique for the cyclone track prediction is based on multiple linear regression technique. The predictor selected for the MME are forecast latitude and longitude positions of cyclone at 12-hr intervals up to 120 hours forecasts from five NWP models namely, IMD-GFS, IMD-WRF, NCEP-GFS, UKMO, and JMA. A statistical cyclone intensity prediction (SCIP) model for predicting 12 hourly cyclone intensity (up to 72 hours) is developed applying multiple linear regression technique. Various dynamical and thermodynamical parameters as predictors are derived from the model outputs of IMD operational Global Forecast System and these parameters are also used for the prediction of rapid intensification. For forecast of inland wind after the landfall of a cyclone, an empirical technique is developed. This paper briefly describes the forecast system CPS and evaluates the performance skill for two recent cyclones Viyaru (non-intensifying) and Phailin (rapid intensifying), converse in nature in terms of track and intensity formed over Bay of Bengal in 2013. The evaluation of performance shows that the GPP analysis at early stages of development of a low pressure system indicated the potential of the system for further intensification. The 12-hourly track forecast by MME, intensity forecast by SCIP model, and rapid intensification forecasts are found to be consistent and very useful to the operational forecasters. The error

  5. Sampling Odor Substances by Mist-Cyclone System

    Science.gov (United States)

    Matsubara, Osamu; Jiang, Zhiheng; Toyama, Shigeki

    2009-05-01

    Many techniques have been developed to measure odor substances. However most of those methods are based on using aquatic solutions(1),(2). Many odor substances specifically at low density situation, are difficult to dissolve into water. To absorb odor substances and obtain highest concentration solutions are key problems for olfactory systems. By blowing odor substances contained air mixture through mist of water and then separating the liquid from two-phases fluid with a cyclone unit a high concentration solution was obtained.

  6. Characteristics and development of European cyclones with tropical origin in reanalysis data

    Science.gov (United States)

    Dekker, Mark M.; Haarsma, Reindert J.; Vries, Hylke de; Baatsen, Michiel; Delden, Aarnout J. van

    2017-03-01

    Major storm systems over Europe frequently have a tropical origin. This paper analyses the characteristics and dynamics of such cyclones in the observational record, using MERRA reanalysis data for the period 1979-2013. By stratifying the cyclones along three key phases of their development (tropical phase, extratropical transition and final re-intensification), we identify four radically different life cycles: the tropical cyclone and extratropical cyclone life cycles, the classic extratropical transition and the warm seclusion life cycle. More than 50% of the storms reaching Europe from low latitudes follow the warm seclusion life cycle. It also contains the strongest cyclones. They are characterized by a warm core and a frontal T-bone structure, with a northwestward warm conveyor belt and the effects of dry intrusion. Rapid deepening occurs in the latest phase, around their arrival in Europe. Both baroclinic instability and release of latent heat contribute to the strong intensification. The pressure minimum occurs often a day after entering Europe, which enhances the potential threat of warm seclusion storms for Europe. The impact of a future warmer climate on the development of these storms is discussed.

  7. Extratropical transitioning in the RMS Japan typhoon wind field model

    Science.gov (United States)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  8. Prevention of destructive tropical and extratropical storms, hurricanes, tornadoes, dangerous thunderstorms, and catastrophic floods

    Directory of Open Access Journals (Sweden)

    E. Yu. Krasilnikov

    2002-01-01

    Full Text Available Tropical cyclones and storms, hurricanes, powerful thunderclouds, which generate tornadoes, destructive extratropical cyclones, which result in catastrophic floods, are the powerful cloud systems that contain huge amount of water. According to the hypothesis argued in this paper, an electric field coupled with powerful clouds and electric forces play a cardinal role in supporting this huge mass of water at a high altitude in the troposphere and in the instability of powerful clouds sometimes during rather a long time duration. Based on this hypothesis, a highly effective method of volume electric charge neutralization of powerful clouds is proposed. It results in the decrease in an electric field, a sudden increase in precipitation, and subsequent degradation of powerful clouds. This method, based on the natural phenomenon, ensures the prevention of the intensification of tropical and extratropical cyclones and their transition to the storm and hurricane (typhoon stages, which makes it possible to avoid catastrophic floods. It also ensures the suppression of severe thunderclouds, which, in turn, eliminates the development of dangerous thunderstorms and the possibility of the emergence and intensification of tornadoes.

  9. Theoretical investigation of pressure drop in combined cyclone and fabric filter systems

    Science.gov (United States)

    Dirgo, John A.; Cooper, Douglas W.

    Computer simulations were conducted to investigate potential pressure drop reductions obtainable by combining cyclones, as pre-collectors, with fabric filters. The Leith-Licht model was used to characterize cyclone emissions and the specific resistance ( K2) of the fabric filter dust cake was calculated from an empirical correlation. Several important dimensionless groups were identified and evaluated. One group, the product of the ratio of the dust cake specific resistances expected with and without the cyclone and the mass penetration of the cyclone, ( K2/ K2) Pn, indicates whether a pressure drop reduction is possible. A correlation was developed for this group as a function of the size properties of the inlet dust (particle mass median diameter and geometric standard deviation) and the cyclone particle cut diameter. Expressions were derived for the break-even time, the duration of filtration with the cyclone needed to show a pressure drop reduction in comparison with filtration without the cyclone. It is shown that in previously reported experiments and simulations indicating an advantage for the combined cyclone-fabric filter system, filtration cycles were typically longer than the break-even time; those showing no improvement typically had filtration times shorter than the break-even time.

  10. Polar Cyclone Identification from 4D Climate Data in a Knowledge-Driven Visualization System

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2016-09-01

    Full Text Available Arctic cyclone activity has a significant association with Arctic warming and Arctic ice decline. Cyclones in the North Pole are more complex and less developed than those in tropical regions. Identifying polar cyclones proves to be a task of greater complexity. To tackle this challenge, a new method which utilizes pressure level data and velocity field is proposed to improve the identification accuracy. In addition, the dynamic, simulative cyclone visualized with a 4D (four-dimensional wind field further validated the identification result. A knowledge-driven system is eventually constructed for visualizing and analyzing an atmospheric phenomenon (cyclone in the North Pole. The cyclone is simulated with WebGL on in a web environment using particle tracing. To achieve interactive frame rates, the graphics processing unit (GPU is used to accelerate the process of particle advection. It is concluded with the experimental results that: (1 the cyclone identification accuracy of the proposed method is 95.6% when compared with the NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data; (2 the integrated knowledge-driven visualization system allows for streaming and rendering of millions of particles with an interactive frame rate to support knowledge discovery in the complex climate system of the Arctic region.

  11. Simulation Study of Extratropical Cyclone Activities on the Nuclear Material Dispersion from the Damaged Fukushima Nuclear Power Plant%气旋活动对福岛核污染物扩散影响的模拟研究

    Institute of Scientific and Technical Information of China (English)

    王鹏飞; 费建芳; 程小平; 黄小刚; 王益柏

    2013-01-01

    基于拉格朗日粒子扩散模式FLEXPART-WRF,根据Stohl推导的日本福岛第一核电站核事故(下称福岛核事故)发生后40d内的137 Cs排放量数据,对核污染物在中尺度区域的扩散传输进行数值模拟研究,并选取近5年3次典型气旋个例(北方气旋、南方气旋和缓慢移动气旋)进行敏感性试验,以分析不同气旋系统对污染物扩散的影响.结果表明:福岛核事故发生后,受中纬度西风带影响,核污染物主要向东部太平洋方向扩散;核事故发生后的5d,受北方气旋和日本南部局地中尺度气旋2次气旋过程的影响,核污染物对日本本土部分地区影响较大,但影响时间不长.典型气旋个例的敏感性模拟试验结果表明:北方气旋和南方气旋均可使核污染物对日本本土造成一定的影响,但由于气旋移动速度较快,影响日本岛的时间较短,沉降量也较小;当出现缓慢移动气旋影响日本和周边地区时,可致污染物影响日本岛的时问延长,并直接进入东亚大陆.%In this study the Lagrangian particle dispersion model KLEXPART-WRF was adopted to simulate the nuclear radiation transport in the atmosphere for the crisis of the Fukushima Daiichi nuclear power plant, according to the emissions inventory of 137Cs. Besides the simulation for the nuclear accident period, three simulations for the sensitivity were also conducted for three kinds of typical cyclone activity processes including the northern cyclone, the southern cyclone and the quasi-stationary cyclone to reveal the possible transport path of radioactive materials. The results showed that after the occurrence of the accident, the radioactive materials primarily spread toward the eastern Pacific Ocean under the effect of the westerlies in the mid-latitudes. In the first five days, nuclear contaminants produced a short-term but significant impact on the Japan Island under influences of two cyclone processes of a northern cyclone and a

  12. A Study of the Extratropical Transformation of Typhoon Winnie (1997)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The complicated evolutive process of how a tropical cyclone transforms into an extratropical cyclone is still an unresolved issue to date, especially one which arises in a weakly baroclinic environment. Typhoon Winnie (1997) is studied during its extratropical transformation stage of extratropical transition (ET)with observational data and numerical simulations. Results show that Winnie experienced its extratropical transformation to the south of the subtropical high without intrusion of the mid-latitude baroclinic zone.This is significantly different from previous studies. Analyses reveal that the cold air, which appeared in the north edge of Winnie circulation, resulted from the precipitation drag and cooling effect of latent heat absorption associated with the intense precipitation there. The cooling only happened below 3 km and the greatest cooling was below 1 km. With the cold air and its advection by the circulation of Winnie, a front was formed in the lower troposphere. The front above is related not only to the cooling in the lower level but also to the warming effect of latent heat release in the middle-upper levels. The different temperature variation in the vertical caused the temperature gradient over Winnie and resulted in the baroclinicity.

  13. Interactions between tropical cyclones and mid-latitude systems in the Northeastern Pacific

    Science.gov (United States)

    Lugo, A.; Abarca, S. F.; Raga, G. B.; Vargas, D. C.

    2014-12-01

    Major challenges in tropical meteorology include the short-term forecast of tropical cyclone (TC) intensity, which is defined as the maximum tangential wind. Several efforts have been made in order to reach this goal over the last decade: Among these efforts, the study of lightning in the TC inner core (the region inside a disc of 100 km radius from the center) as a proxy to deep convection, has the potential to be used as a predictor to forecast intensity (DeMaria et al, 2012, Mon. Wea. Rev., 140, 1828-1842).While most studies focus their objectives in studying the lightning flash density in the inner core, we study the probability of flash occurrence for intensifying and weakening cyclones. We have analyzed the trajectories of the observed 62 tropical cyclones that developed in the basin from 2006 to 2009, and classified them into separate clusters according to their trajectories. These clusters can broadly be described as having trajectories mostly oriented: East-West, towards the central Pacific, NW far from the Mexican coast, parallel to the Mexican coast and recurving towards the Mexican coast.We estimate that probability of inner core lightning occurrence increases as cyclones intensify but the probability rapidly decrease as the systems weaken. This is valid for cyclones in most of the clusters. However, the cyclones that exhibit trajectories that recurve towards the Mexican coast, do not present the same relationship between intensity and inner-core lightning probability, these cyclones show little or no decrease in the lightning occurrence probability as they weaken.We hypothesize that one of the reasons for this anomalous behavior is likely the fact that these cyclones interact with mid-latitude systems. Mid-latitude systems are important in determining the recurving trajectory but they may also influence the TC by advecting mid-level moisture towards the TC inner core. This additional supply of moisture as the system is approaching land may enhance deep

  14. Cyclogenesis Frequency Changes of Extratropical Cyclones in the Northern Hemisphere and East Asia Revealed by ERA40 Reanalysis Data%ERA40再分析资料揭示的北半球和东亚地区温带气旋生成频率变化

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇; 李巧萍

    2012-01-01

    本文利用欧洲中心再分析数据ERA40的6小时间隔海平面气压场和一种改进的客观判定和追踪方法研究1958—2001年北半球和东亚地区温带气旋生成频率的气候态、年代际变化及可能原因。结果表明:(1)北半球温带气旋的源地主要位于北美东部(落基山下游地区)、西北大西洋地区、格陵兰至欧洲北部地区、蒙古地区和日本至西北太平洋地区。大洋的西岸和陡峭地形的背风坡有利于大气斜压性的增强和正涡度的发展,从而有利于地面气旋的形成。(2)年、冬季和春季30°~60°N气旋生成数目呈现减少的变化趋势,60°~90°N地区的气旋生成数呈增加的变化趋势。这在一定程度上支持了北半球风暴路径北移的观点。60°N以南和以北的温带气旋数目同北极涛动指数(AO)分别呈现负相关和正相关,这种相关性在年、春季和秋季最为显著。(3)1958--2001年东亚地区的年气旋数目呈现明显的年代际变化。20世纪60年代至80年代中期40°~60°N、80°~140°E地区气旋数目呈增加趋势,而80年代中期之后温带气旋数目则锐减,主要原因是80年代以后该地区大气斜压性减弱,更高纬度地区的大气斜压性增强,从而导致了气旋源地的北移。在较低纬带的20°~40°N、110°~160°E地区气旋数目线性增加,这主要是由于位于40°~55°N的北太平洋风暴轴有向低纬度偏移的变化趋势造成的。%A climatology of cyclogenesis frequency of extratropical cyclones in the Northern Hemisphere and East Asia for the years of 1958 to 2001, and the interdecadal variation and possible causes, were ana- lyzed by applying an improved objective detecting and tracking algorithm to the six-hourly sea-level pres- sure fields in the European Center for Medium-range Weather Forecasts reanalysis data ERA40. The result shows that: (1) major source regions of

  15. Data denial experiments for extratropical transition

    Directory of Open Access Journals (Sweden)

    Doris Anwender

    2012-11-01

    Full Text Available Data denial experiments using the European Centre for Medium-Range Weather Forecasts (ECMWF model are designed to investigate the value of targeted observations for historical extratropical transition (ET cases over the Atlantic. The impact of removing data from specified locations linked to the ET development is therefore examined. It is shown that the impact of denying data in the near tropical cyclone (TC environment is, on average, as important as denying data in mid-latitude sensitive regions determined using extratropical singular vectors (SV. The impact of data denial over TC regions propagates downstream from the Atlantic towards Europe, with a maximum degradation at day 4. This degradation is mainly attributed to the data denial at the TC stage, i.e. before ET is completed. When data are denied on mid-latitude sensitive regions, the largest degradation is found around day 2 and also after the day 4 forecast. In general, the loss of information content is larger when data are denied in mid-latitude sensitive areas because these identify dynamically active regions. In both denial experiments, aircraft and satellite radiance data are the most influential observations. For the selected case of Hurricane Irene, the largest degradations are found for forecasts initialised while Irene reached its peak intensity. If observations are denied in the near storm environment, the TC mostly disappears from the analysis and the subsequent forecast. This allows the impact of Irene on the formation of the downstream cut-off low to be investigated.

  16. The Cyclone Global Navigation Satellite System (CYGNSS) - Analysis and Data Assimilation for Tropical Convection

    Science.gov (United States)

    Li, Xuanli; Lang, Timothy J.; Mecikalski, John; Castillo, Tyler; Hoover, Kacie; Chronis, Themis

    2017-01-01

    Cyclone Global Navigation Satellite System (CYGNSS): a constellation of 8 micro-satellite observatories launched in November 2016, to measure near-surface oceanic wind speed. Main goal: To monitor surface wind fields of the Tropical Cyclones' inner core, including regions beneath the intense eye wall and rain bands that could not previously be measured from space; Cover 38 deg S -38 deg N with unprecedented temporal resolution and spatial coverage, under all precipitating conditions Low flying satellite: Pass over ocean surface more frequently than one large satellite. A median(mean) revisit time of 2.8(7.2) hrs.

  17. Influences of tropical-extratropical interaction on the multidecadal AMOC variability in the NCEP climate forecast system

    Science.gov (United States)

    Huang, Bohua; Hu, Zeng-Zhen; Schneider, Edwin K.; Wu, Zhaohua; Xue, Yan; Klinger, Barry

    2012-08-01

    We have examined the mechanisms of a multidecadal oscillation of the Atlantic Meridional Overturning Circulation (AMOC) in a 335-year simulation of the Climate Forecast System (CFS), the climate prediction model developed at the National Centers for Environmental Prediction (NCEP). Both the mean and seasonal cycle of the AMOC in the CFS are generally consistent with observation-based estimates with a maximum northward volume transport of 16 Sv (106 m3/s) near 35°N at 1.2 km. The annual mean AMOC shows an intermittent quasi 30-year oscillation. Its dominant structure includes a deep anomalous overturning cell (referred to as the anomalous AMOC) with amplitude of 0.6 Sv near 35°N and an anomalous subtropical cell (STC) of shallow overturning spanning across the equator. The mechanism for the oscillation includes a positive feedback between the anomalous AMOC and surface wind stress anomalies in mid-latitudes and a negative feedback between the anomalous STC and AMOC. A strong AMOC is associated with warm sea surface temperature anomaly (SSTA) centered near 45°N, which generates an anticyclonic easterly surface wind anomaly. This anticyclonic wind anomaly enhances the regional downwelling and reinforces the anomalous AMOC. In the mean time, a wind-evaporation-SST (WES) feedback extends the warm SSTA to the tropics and induces a cyclonic wind stress anomaly there, which drives a tropical upwelling and weakens the STC north of the equator. The STC anomaly, in turn, drives a cold upper ocean heat content anomaly (HCA) in the northern tropical Atlantic and weakens the meridional heat transport from the tropics to the mid-latitude through an anomalous southward western boundary current. The anomalous STC transports cold HCA from the subtropics to the mid-latitudes, weakening the mid-latitude deep overturning.

  18. Influences of tropical-extratropical interaction on the multidecadal AMOC variability in the NCEP climate forecast system

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohua; Schneider, Edwin K.; Klinger, Barry [Gorge Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Hu, Zeng-Zhen; Xue, Yan [National Centers for Environmental Prediction/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Wu, Zhaohua [Florida State University, Department of Earth, Ocean, and Atmospheric Science, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL (United States)

    2012-08-15

    We have examined the mechanisms of a multidecadal oscillation of the Atlantic Meridional Overturning Circulation (AMOC) in a 335-year simulation of the Climate Forecast System (CFS), the climate prediction model developed at the National Centers for Environmental Prediction (NCEP). Both the mean and seasonal cycle of the AMOC in the CFS are generally consistent with observation-based estimates with a maximum northward volume transport of 16 Sv (10{sup 6} m{sup 3}/s) near 35 N at 1.2 km. The annual mean AMOC shows an intermittent quasi 30-year oscillation. Its dominant structure includes a deep anomalous overturning cell (referred to as the anomalous AMOC) with amplitude of 0.6 Sv near 35 N and an anomalous subtropical cell (STC) of shallow overturning spanning across the equator. The mechanism for the oscillation includes a positive feedback between the anomalous AMOC and surface wind stress anomalies in mid-latitudes and a negative feedback between the anomalous STC and AMOC. A strong AMOC is associated with warm sea surface temperature anomaly (SSTA) centered near 45 N, which generates an anticyclonic easterly surface wind anomaly. This anticyclonic wind anomaly enhances the regional downwelling and reinforces the anomalous AMOC. In the mean time, a wind-evaporation-SST (WES) feedback extends the warm SSTA to the tropics and induces a cyclonic wind stress anomaly there, which drives a tropical upwelling and weakens the STC north of the equator. The STC anomaly, in turn, drives a cold upper ocean heat content anomaly (HCA) in the northern tropical Atlantic and weakens the meridional heat transport from the tropics to the mid-latitude through an anomalous southward western boundary current. The anomalous STC transports cold HCA from the subtropics to the mid-latitudes, weakening the mid-latitude deep overturning. (orig.)

  19. Energy transformations associated with the synoptic and planetary scales during the evolution of a blocking anticyclone and an upstream explosively-developing cyclone

    OpenAIRE

    Smith, Phillip J.; Tsou, Chih-Hua

    2011-01-01

    Energy transformations associated with a wave system that included the development of a blocking anticyclone over the North Atlantic Ocean and the upstream explosive-development of an extratropical cyclone are studied for the period 17–21 January 1979. Included in the investigation are eddy kinetic energy (KE), release of eddy potential energy (CE), generation of eddy kinetic energy (GK), and exchange between eddy and zonal kinetic energy (CK). In addition, these quantities were partitioned i...

  20. Extratropical Cyclogenesis and Frontal Waves on Mars: Influences on Dust, Weather and the Planet's climate

    Science.gov (United States)

    Hollingsworth, J. L.; Kahre, Melinda A.

    2012-01-01

    Between late autumn and early spring, middle and high latitudes on Mars exhibit strong equatortopole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic periodwaves) [1,2]. For a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, these large-scale, extratropical weather disturbances are critical components of the global circulation. The wavelike disturbances act as agents in the transport of heat and momentum between low and high latitudes of the planet. Through cyclonic/anticyclonic winds, intense shear deformations, contractions-dilatations in temperature and density, and sharp perturbations amongst atmospheric tracers (i.e., dust, volatiles (e.g., water vapor) and condensates (e.g., water-ice cloud particles)), Mars extratropical weather systems have significant subsynoptic scale ramifications by supporting atmospheric frontal waves (Fig. 1).

  1. Cyclonic multiphase flow measurement system GLCC®1 for oil well capacity evaluation

    Directory of Open Access Journals (Sweden)

    J.M. Godoy–Alcántar

    2008-10-01

    Full Text Available This paper shows the development of a portable multiphase flow measurement system based in cyclonic separation technology GLCC@1. This system is aimed for oil well measurement and was developed in three phases; the first devoted to the geometric design of a cyclonic separator by means of design software GLCC V7.8 and the selection of measurement instrumentation and flux control valves. In the second phase, the automatic control system was designed for the implementation of four control strategies each one related with a possible scenario of the well behavior. The third constitutes the integration of the measurement and control devices through a user interface aimed for visualization, information processing and system's operation and control. Experimental results in oil well measurements show the efficiency and workability of the integrated system.

  2. Atmospheric pressure variations at extratropical latitudes associated with Forbush decreases of galactic cosmic rays

    Science.gov (United States)

    Artamonova, I.; Veretenenko, S.

    2014-12-01

    Changes of troposphere pressure associated with short-time variations of galactic cosmic rays (GCRs) taking place in the Northern hemisphere's cold months (October-March) were analyzed for the period 1980-2006, NCEP/NCAR reanalysis data being used. Noticeable pressure variations during Forbush decreases of GCRs were revealed at extratropical latitudes of both hemispheres. The maxima of pressure increase were observed on the 3rd-4th days after the event onsets over Northern Europe and the European part of Russia in the Northern hemisphere, as well as on the 4th-5th days over the eastern part of the South Atlantic opposite Queen Maud Land and over the d'Urville Sea in the Southern Ocean. According to the weather chart analysis, the observed pressure growth, as a rule, results from the weakening of cyclones and intensification of anticyclone development in these areas. The presented results suggest that cosmic ray variations may influence the evolution of extratropical baric systems and play an important role in solar-terrestrial relationships.

  3. The Tropical UTLS JAPE Bubble and its Role Driving Extratropical Weather

    Science.gov (United States)

    Tripoli, G. J.; Nytes, L.

    2015-12-01

    Latent heating by tropical weather systems produces vertical mass fluxes of high potential temperature that fill upper isentropic layers with mass. This produces an expanded isentropic layer in the tropical Upper troposphere - Lower Stratosphere (UTLS) of elevated potential energy. Because this elevated potential energy is converted to kinetic energy if it flows poleward, we call it JAPE (Jet Available Potential Energy). This conversion effectively prevents wholesale movement into the extratropics, an effect of inertial stability due to the Earth's rotation. As a result, the JAPE takes the form of a potential energy bubble spanning heights between 10 km and 18 km and meridionally between 30N and 30S on average with occasional poleward plumes reaching up to 50 degrees latitude. The JAPE bubble is bounded on its poleward edge by the subtropical jet (STJ) and its upper surface by the elevated tropical tropopause. As potential energy is continually fed into the bubble by tropical convective and tropical cyclone activity, the JAPE bubble builds mass and an increasing potential to surge that mass into the extratropics, leading to "JAPE surge" events. These events occur at weaknesses in the inertial wall of the bubble, usually related to interactions with a polar jet. These surges become energy conduits, infusing the JAPE (and reducing the bubble mass) into the extratropical Rossby wave stream via a STJ-PJ interaction. The poleward JAPE surge events are periodic and occur in 3-5 locations simultaneously around the globe, usually in the winter hemisphere. At the oral presentation, a 36 year analysis of the behavior of the JAPE bubble will be presented, and its role in energizing the Rossby wave train will be discussed.

  4. Cyclone performance by velocity

    Science.gov (United States)

    Cyclones are used almost exclusively in the US cotton ginning industry for emission abatement on pneumatic conveying system exhausts because of their high efficiency, and low capital and operating cost.. Cyclone performance is improved by increasing collection effectiveness or decreasing energy cons...

  5. Simulations of Severe Tropical Cyclone Nargis over the Bay of Bengal Using RIMES Operational System

    Science.gov (United States)

    Raju, P. V. S.; Potty, Jayaraman; Mohanty, U. C.

    2012-10-01

    The Regional Integrated Multi-Hazard Early Warning System (RIMES), an international, intergovernmental organization based in Thailand is engaged in disaster risk reduction over the Asia-Pacific region through early warning information. In this paper, RIMES' customized Weather Research Forecast (WRF) model has been used to evaluate the simulations of cyclone Nargis which hit Myanmar on 2 May 2008, the most deadly severe weather event in the history of Myanmar. The model covers a domain of 35ºE to 145ºE in the east—west direction and 12ºS to 40ºN in the north—south direction in order to cover Asia and east Africa with a resolution of 9 km in the horizontal and 28 vertical levels. The initial and boundary conditions for the simulations were provided by the National Center for Environmental Prediction-Global Forecast System (NCEP-GFS) available at 1º lon/lat resolution. An attempt is being made to critically evaluate the simulation of cyclone Nargis by seven set of simulations in terms of track, intensity and landfall time of the cyclone. The seven sets of model simulations were initialized every 12 h starting from 0000 UTC 28 April to 01 May 2008. Tropical Rainfall Measurement Mission (TRMM) precipitation (mm) is used to evaluate the performance of the simulations of heavy rainfall associated with the tropical cyclone. The track and intensity of the simulated cyclone are compared by making use of Joint Typhoon Warning Center (JTWC) data sets. The results indicate that the landfall time, the distribution and intensity of the rainfall, pressure and wind field are well simulated as compared with the JTWC estimates. The average landfall track error for all seven simulations was 64 km with an average time error of about 5 h. The average intensity error of central pressure in all the simulations were found out to be approximately 6 hPa more than the JTWC estimates and in the case of wind, the simulations under predicted it by an average of 12 m s-1.

  6. A note on boundary-layer friction in baroclinic cyclones

    CERN Document Server

    Boutle, I A; Belcher, S E; Plant, R S

    2008-01-01

    The interaction between extratropical cyclones and the underlying boundary layer has been a topic of recent discussion in papers by Adamson et. al. (2006) and Beare (2007). Their results emphasise different mechanisms through which the boundary layer dynamics may modify the growth of a baroclinic cyclone. By using different sea-surface temperature distributions and comparing the low-level winds, the differences are exposed and both of the proposed mechanisms appear to be acting within a single simulation.

  7. Evolution of Tropical Cyclone Characteristics and Forecast Assessment

    Science.gov (United States)

    2016-06-07

    the shore- or sea-based asset and the size of the risk is measured by the total impact of the tropical cyclone in terms of costs incurred to take...understanding and prediction of the extratropical transition phase of a decaying tropical cyclone. A secondary long- term goal of this research is to measure ...the so-called “ cost /loss ratio” decision model. An alternative to the cost /loss type of decision process that may be applied to individual tropical

  8. Polar Cyclone Identification from 4D Climate Data in a Knowledge-Driven Visualization System

    OpenAIRE

    Feng Wang; Wenwen Li; Sizhe Wang

    2016-01-01

    Arctic cyclone activity has a significant association with Arctic warming and Arctic ice decline. Cyclones in the North Pole are more complex and less developed than those in tropical regions. Identifying polar cyclones proves to be a task of greater complexity. To tackle this challenge, a new method which utilizes pressure level data and velocity field is proposed to improve the identification accuracy. In addition, the dynamic, simulative cyclone visualized with a 4D (four-dimensional) wind...

  9. Comparison of Mid-latitude Cyclones in Sea Level Pressure, Gepotential Height and Vorticity Fields

    Science.gov (United States)

    Raible, Christoph C.; Blender, Richard; Fraedrich, Klaus

    2013-04-01

    The mid-latitudes are dominated by diurnal variability, which is related to traveling high- and low-pressure systems. The lows or cyclones are a major source of natural hazards. This has led to growing interest in the scientific community to develop Eulerian and Lagrangian measures and to analyze the atmospheric high-frequency variability. One important issue is that there is no straight forward definition of cyclones resulting in a large variety of so-called cyclone detection and tracking methods. Each of these methods relies on different input fields which are related to specific features of a cyclone, e.g., sea level pressure (SLP), which specifically focuses on the mass aspect of the velocity field. Recently, the available methods have been compared with respect to climatology and life cycles using the ERA interim data set (Neu et al. 2013). Based on this study we investigate different fields as input for one specific method. We focus on the three mostly used input data, sea level pressure (SLP), 1000-hPa gepotential height (Z1000) and 850-hPa vorticity (850VOR). The cyclone detection and tracking method developed by Blender et al. (1997) is used and we apply it to ERA interim data in the 1.5 x 1.5 resolution. The method was mainly applied for Z1000 and the Northern Hemisphere (e.g., Blender et al. 1997; Raible et al. 2008). To compare the tracks and cyclone characteristics obtained from the different input data we need to adapt critical parameters of the method in such a way that comparable numbers of cyclone centers are identified in either field. The target is set to the number of cyclone centers in northern hemispheric winter. This enables us to assess the seasonal and hemispheric dependence. Preliminary results show that the agreement between cyclones based on SLP and Z1000 varies between roughly 70 to 80% depending on the season and the hemisphere. Spatially, most of the differences are found around orographic features like Greenland. An interesting

  10. Abrupt transitions in the NAO control of explosive North Atlantic cyclone development

    Science.gov (United States)

    Gómara, Iñigo; Rodríguez-Fonseca, Belén; Zurita-Gotor, Pablo; Ulbrich, Sven; Pinto, Joaquim G.

    2016-11-01

    Explosive cyclones are intense extra-tropical low pressure systems featuring large deepening rates. In the Euro-Atlantic sector, they are a major source of life-threatening weather impacts due to their associated strong wind gusts, heavy precipitation and storm surges. The wintertime variability of the North Atlantic cyclonic activity is primarily modulated by the North Atlantic Oscillation (NAO). In this study, we investigate the interannual and multi-decadal variability of explosive North Atlantic cyclones using track density data from two reanalysis datasets (NCEP and ERA-40) and a control simulation of an atmosphere/ocean coupled General Circulation Model (GCM—ECHAM5/MPIOM1). The leading interannual and multi-decadal modes of variability of explosive cyclone track density are characterized by a strengthening/weakening pattern between Newfoundland and Iceland, which is mainly modulated by the NAO at both timescales. However, the NAO control of interannual cyclone variability is not stationary in time and abruptly fluctuates during periods of 20-25 years long both in NCEP and ECHAM5/MPIOM1. These transitions are accompanied by structural changes in the leading mode of explosive cyclone variability, and by decreased/enhanced baroclinicity over the sub-polar/sub-tropical North Atlantic. The influence of the ocean is apparently important for both the occurrence and persistence of such anomalous periods. In the GCM, the Atlantic Meridional Overturning Circulation appears to influence the large-scale baroclinicity and explosive cyclone development over the North Atlantic. These results permit a better understanding of explosive cyclogenesis variability at different climatic timescales and might help to improve predictions of these hazardous events.

  11. A Study of Extratropical Transition and Re-Intensification of Typhoon Mindulle (2004)

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiande; WANG Qi; FU Gang; LIU Yulong; TIAN Ying

    2011-01-01

    In this study,the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSUNCAR) Mesoscale Model (MM5) is used to simulate Typhoon Mindulle (2004) at high resolution (3-km grid size).The data from measurements show that in the upper atmosphere the existence of an upper jet is important to the transition cyclone.When Mindulle moved to the area of the upper jet entrance,where high-altitude divergence existed,the pumping of the high-altitude divergence would enhance the vertical motion and low-level cyclone convergence.The enhanced vertical motion was confirmed by the simulation results and indicated that the existence of upper divergence enhanced the vertical motion which was favorable for the maintenance of Typhoon Mindulle.The process of extratropical transition (ET) and re-intensification always accompanies the process of cold air invasion.This process enhances the baroclinicity of the atmosphere and the formation of front at high altitudes,which converts baroclinic potential energy into kinetic energy and strengthens the cyclone vortex.The distributions of equivalent potential temperature (θe) and temperature anomalies show that the warm-core of the typhoon at the tropopause aids the re-intensification of the system.As the typhoon reenters the ocean,latent heat flux (LHF) increases in the north and west and the strong reflectivity and vertical motion occur in the east and southeast,and the west.With the re-intensification of the typhoon the wind field evolves from an oval to a circle at the lower atmosphere,the area coverage by high winds increases,and the distribution of the tangential wind shows an asymmetric pattern.

  12. Evaluation of Model Microphysics Within Precipitation Bands of Extratropical Cyclones

    Science.gov (United States)

    Colle, Brian A.; Yu, Ruyi; Molthan, Andrew L.; Nesbitt, Steven

    2014-01-01

    It is hypothesized microphysical predictions have greater uncertainties/errors when there are complex interactions that result from mixed phased processes like riming. Use Global Precipitation Measurement (GPM) Mission ground validation studies in Ontario, Canada to verify and improve parameterizations. The WRF realistically simulated the warm frontal snowband at relatively short lead times (1014 h). The snowband structire is sensitive to the microphysical parameterization used in WRF. The Goddard and SBUYLin most realistically predicted the band structure, but overpredicted snow content. The double moment Morrison scheme best produced the slope of the snow distribution, but it underpredicted the intercept. All schemes and the radar derived (which used dry snow ZR) underpredicted the surface precipitation amount, likely because there was more cloud water than expected. The Morrison had the most cloud water and the best precipitation prediction of all schemes.

  13. A Climatological Study of Hurricane Force Extratropical Cyclones

    Science.gov (United States)

    2012-03-01

    to weaken. There is some indication that diabatic processes serve as an additional energy source. Brief examination of predictability using ECMWF...Shortly after this time, the storm begins to weaken. There is some indication that diabatic processes serve as an additional energy source. Brief...Their primary energy source comes in the form of a baroclinic zone (meridional temperature gradient). While not a necessary ingredient, diabatic

  14. Evaluation of Model Microphysics Within Precipitation Bands of Extratropical Cyclones

    Science.gov (United States)

    Colle, B.; Molthan, A.; Yu, R.; Stark, D.; Yuter, S. E.; Nesbitt, S. W.

    2013-12-01

    Recent studies evaluating the bulk microphysical schemes (BMPs) within cloud resolving models (CRMs) have indicated large uncertainties and errors in the amount and size distributions of snow and cloud ice aloft. The snow prediction is sensitive to the snow densities, habits, and degree of riming within the BMPs. Improving these BMPs is a crucial step toward improving both weather forecasting and climate predictions. Several microphysical schemes in the Weather Research and Forecasting (WRF) model down to 1.33-km grid spacing are evaluated using aircraft, radar, and ground in situ data from the Global Precipitation Mission Cold-season Precipitation Experiment (GCPEx) experiment, as well as a few years (15 winter storms) of surface measurements of riming, crystal habit, snow density, and radar measurements at Stony Brook, NY (SBNY on north shore of Long Island) during the 2009-2012 winter seasons. Surface microphysical measurements at SBNY were taken every 15 to 30 minutes using a stereo microscope and camera, and snow depth and snow density were also recorded. During these storms, a vertically-pointing Ku-band radar was used to observe the vertical evolution of reflectivity and Doppler vertical velocities. A Particle Size and Velocity (PARSIVEL) disdrometer was also used to measure the surface size distribution and fall speeds of snow at SBNY. For the 15 cases at SBNY, the WSM6, Morrison (MORR), Thompson (THOM2), and Stony Brook (SBU-YLIN) BMPs were validated. A non-spherical snow assumption (THOM2 and SBU-YLIN) simulated a more realistic distribution of reflectivity than spherical snow assumptions in the WSM6 and MORR schemes. The MORR, WSM6, and SBU-YLIN schemes are comparable to the observed velocity distribution in light and moderate riming periods. The THOM2 is ~0.25 m s-1 too slow with its velocity distribution in these periods. In heavier riming, the vertical Doppler velocities in the WSM6, THOM2, and MORR schemes were ~0.25 m s-1 too slow, while the SBU-YLIN was 0.25 to 0.5 m s-1 too fast. Overall, the BMPs simulate a size distribution close to the observed for D 6 mm in the dendrites, side planes, and mixed habit periods, the BMPs are likely not simulating enough aggregation to create a larger size distribution, although the MORR (double moment) scheme seemed to perform best. These SBNY results will be compared with some results from GCPEx for a warm frontal snow band observed at 18 February 2012.

  15. The observed clustering of damaging extratropical cyclones in Europe

    Science.gov (United States)

    Cusack, Stephen

    2016-04-01

    The clustering of severe European windstorms on annual timescales has substantial impacts on the (re-)insurance industry. Our knowledge of the risk is limited by large uncertainties in estimates of clustering from typical historical storm data sets covering the past few decades. Eight storm data sets are gathered for analysis in this study in order to reduce these uncertainties. Six of the data sets contain more than 100 years of severe storm information to reduce sampling errors, and observational errors are reduced by the diversity of information sources and analysis methods between storm data sets. All storm severity measures used in this study reflect damage, to suit (re-)insurance applications. The shortest storm data set of 42 years provides indications of stronger clustering with severity, particularly for regions off the main storm track in central Europe and France. However, clustering estimates have very large sampling and observational errors, exemplified by large changes in estimates in central Europe upon removal of one stormy season, 1989/1990. The extended storm records place 1989/1990 into a much longer historical context to produce more robust estimates of clustering. All the extended storm data sets show increased clustering between more severe storms from return periods (RPs) of 0.5 years to the longest measured RPs of about 20 years. Further, they contain signs of stronger clustering off the main storm track, and weaker clustering for smaller-sized areas, though these signals are more uncertain as they are drawn from smaller data samples. These new ultra-long storm data sets provide new information on clustering to improve our management of this risk.

  16. Picosecond laser surface micro-texturing for the modification of aerodynamic and dust distribution characteristics in a multi-cyclone system

    Directory of Open Access Journals (Sweden)

    Omonigho B. Otanocha

    2016-12-01

    Full Text Available Aerodynamic flow control in a cyclone is critical to its performance. Dust accumulation in a multi-cyclone is undesirable. This research investigated, the effects of laser-patterned Ethylene-Propylene-Diene Monomer (EPDM roof in a commercial multi-cyclone system on its aerodynamic and dust accumulation characteristics. Our experimental data show that strategically designed concentric micro-dimples on the cyclone roof can improve both the aerodynamic performance and dust separation capability in the multi-cyclone system. With specific laser-patterned cyclone roof, up to 78% reduction in dust adhesion was demonstrated in one of the cones (cone 9. With the 315-μm diameter micro-dimples on EPDM roof, it was observed that dimples located close to the vortex finder caused an increase in the reverse airflows in the cyclone, thereby effecting entrainment of dust. The overall dust separation efficiency of the multi-cyclone system was at an average of 99.9% with the laser-textured roof, hence no adverse effect on the original cyclone system, in spite of the reported improvements in dust adhesion reduction.

  17. Dynamical system analysis of a low-order tropical cyclone model

    Directory of Open Access Journals (Sweden)

    Daria Schönemann

    2012-02-01

    Full Text Available Tropical cyclone dynamics is investigated by means of a conceptual box model. The tropical cyclone (TC is divided into three regions, the eye, eyewall and ambient region. The model forms a low-order dynamical system of three ordinary differential equations. These are based on entropy budget equations comprising processes of surface enthalpy transfer, entropy advection, convection and radiative cooling. For tropical ocean parameter settings, the system possesses four non-trivial steady state solutions when the sea surface temperature (SST is above a critical value. Two steady states are unstable while the two remaining states are stable. Bifurcation diagrams provide an explanation why only finite-amplitude perturbations above a critical SST can transform into TCs. Besides SST, relative humidity of the ambient region forms an important model parameter. The surfaces that describe equilibria as a function of SST and relative humidity reveal a cusp-catastrophe where the two non-trivial equilibria split into four. Within the model regime of four equilibria, cyclogenesis becomes very unlikely due to the repelling and attracting effects of the two additional equilibria. The results are in qualitative agreement with observations and evince the relevance of the simple model approach to the dynamics of TC formation and its maximum potential intensity.

  18. New Perspectives on Intermountain Cyclones and Cold Fronts

    Science.gov (United States)

    Steenburgh, W. J.; West, G.; Neuman, C.; Shafer, J.; Jeglum, M.; Bosart, L. F.; Lee, T.

    2011-12-01

    The topography in and around the Intermountain West strongly affects the genesis, migration, and lysis of extratropical cyclones and cold fronts. In this presentation, we summarize new perspectives on Intermountain cyclone and cold-front evolution derived from recent climatological, observational, and modeling studies based on high-density observations and high-resolution reanalyses and numerical simulations. Recent high-resolution reanalyses show that Intermountain cyclone activity is greatest in two distinct regions. The first, which we call the Great Basin cyclone region, extends northeastward from the southern high Sierra to the Great Salt Lake Basin of northwest Utah. The second, which we call the Canyonlands cyclone region, lies over the upper Colorado River Basin of southeast Utah, a lowland region between the mountains and plateaus of central Utah and the Colorado Rockies. Composites of strong Intermountain cyclones generated in cross-Sierra (210-300°) 500-hPa flow show that cyclogenesis is preceeded by the development of the Great Basin Confluence Zone (GBCZ), a regional airstream boundary that extends downstream from the Sierra Nevada. Cyclogenesis occurs along the GBCZ as large-scale ascent develops over the Intermountain West in advance of an approaching upper-level trough. Flow splitting around the high Sierra and the presence of low-level baroclinity along the GBCZ suggest that Intermountain Cyclogenesis might be better conceptualized from a potential vorticity perspective than from traditional quasigeostrophic models of lee cyclogenesis. Surface observations indicate that the frequency of strong cold-frontal passages increases dramatically from the Cascade-Sierra Mountains to northern Utah, suggesting that the Intermountain West is a frequent cold-frontal breeding ground. Two case studies help illustrate the mechanisms contributing to these strong cold-frontal passages. During the 2002 Tax Day Cyclone, strong contraction (i.e., deformation and

  19. Development of an Adaptable Display and Diagnostic System for the Evaluation of Tropical Cyclone Forecasts

    Science.gov (United States)

    Kucera, P. A.; Burek, T.; Halley-Gotway, J.

    2015-12-01

    NCAR's Joint Numerical Testbed Program (JNTP) focuses on the evaluation of experimental forecasts of tropical cyclones (TCs) with the goal of developing new research tools and diagnostic evaluation methods that can be transitioned to operations. Recent activities include the development of new TC forecast verification methods and the development of an adaptable TC display and diagnostic system. The next generation display and diagnostic system is being developed to support evaluation needs of the U.S. National Hurricane Center (NHC) and broader TC research community. The new hurricane display and diagnostic capabilities allow forecasters and research scientists to more deeply examine the performance of operational and experimental models. The system is built upon modern and flexible technology that includes OpenLayers Mapping tools that are platform independent. The forecast track and intensity along with associated observed track information are stored in an efficient MySQL database. The system provides easy-to-use interactive display system, and provides diagnostic tools to examine forecast track stratified by intensity. Consensus forecasts can be computed and displayed interactively. The system is designed to display information for both real-time and for historical TC cyclones. The display configurations are easily adaptable to meet the needs of the end-user preferences. Ongoing enhancements include improving capabilities for stratification and evaluation of historical best tracks, development and implementation of additional methods to stratify and compute consensus hurricane track and intensity forecasts, and improved graphical display tools. The display is also being enhanced to incorporate gridded forecast, satellite, and sea surface temperature fields. The presentation will provide an overview of the display and diagnostic system development and demonstration of the current capabilities.

  20. AIRS impact on the analysis and forecast track of tropical cyclone Nargis in a global data assimilation and forecasting system

    Science.gov (United States)

    Reale, O.; Lau, W. K.; Susskind, J.; Brin, E.; Liu, E.; Riishojgaard, L. P.; Fuentes, M.; Rosenberg, R.

    2009-03-01

    Tropical cyclones in the northern Indian Ocean pose serious challenges to operational weather forecasting systems, partly due to their shorter lifespan and more erratic track, compared to those in the Atlantic and the Pacific. Moreover, the automated analyses of cyclones over the northern Indian Ocean, produced by operational global data assimilation systems (DASs), are generally of inferior quality than in other basins, partly because of asymmetric data distribution and the absence of targeted observations inside cyclones. In this work it is shown that the assimilation of Atmospheric Infrared Sounder (AIRS) temperature retrievals under partial cloudy conditions can significantly impact the representation of the cyclone Nargis (which caused devastating loss of life in Myanmar in May 2008) in a global DAS. Forecasts produced from these improved analyses by a global model produce substantially smaller track errors. The impact of the assimilation of clear-sky radiances on the same DAS and forecasting system is positive, but smaller than the one obtained by ingestion of AIRS retrievals, probably due to poorer coverage.

  1. Economic costs of extratropical storms under climate change: An application of FUND

    Science.gov (United States)

    Narita, D.; Tol, R.; Anthoff, D.

    2009-12-01

    Extratropical cyclones have attracted some attention in climate policy circles as a possible significant damage factor of climate change. This study conducts an assessment of economic impacts of increased storm activities under climate change with the integrated assessment model FUND 3.5. FUND is a model that calculates damages of climate change for 16 regions by making use of exogenous scenarios of socioeconomic variables (for details of our estimation approach, see our working paper whose URL is indicated below). Our estimation shows that in the base case, the direct economic damage of enhanced storms due to climate change amounts to $2.8 billion globally (approximately 38% of the total economic loss of storms at present) at the year 2100, while the ratio to the world GDP is 0.0009%. The regional results (Figure 1) indicate that the economic effect of extratropical storms with climate change would have relatively minor importance for the US (USA): The enhanced extratropical storm damage (less than 0.001% of GDP for the base case) is one order of magnitude lower than the tropical cyclone damage (roughly 0.01% GDP) calculated by the same version of FUND. In the regions without strong tropical cyclone influence, such as Western Europe (WEU) and Australia and New Zealand (ANZ), the extratropical storms might have some more significance as a possible damage factor of climate change. Especially for the latter, the direct economic damage could amount to more than 0.006% of GDP. Still, the impact is small relative to the income growth expected in these regions. Figure 1. Increased direct economic loss at the year 2100 for selected regions (results are shown for the three different baselines: the years 1986-2005, 1976-2005, and 1996-2005). US - USA; Canada - CAN; Western Europe - WEU; Australia and New Zealand - ANZ.

  2. Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

    Directory of Open Access Journals (Sweden)

    Hisashi Ozawa

    2015-01-01

    Full Text Available The formation process of circulatory motion of a tropical cyclone is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the first and second laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation and dissipation rates of mechanical energy in the fluid system. We find from this formulation and data analysis that the thermodynamic efficiency of tropical cyclones is about 40% lower than the Carnot maximum efficiency because of the presence of thermal dissipation due to irreversible transport of sensible and latent heat in the atmosphere. We show that a tropical cyclone tends to develop within a few days through a feedback supply of mechanical energy when the sea surface temperature is higher than 300 K, and when the horizontal scale of circulation becomes larger than the vertical height of the troposphere. This result is consistent with the critical radius of 50 km and the corresponding central pressure of about 995 hPa found in statistical properties of typhoons observed in the western North Pacific.

  3. Cyclone reactor

    Science.gov (United States)

    Converse, Alvin O.; Grethlein, Hans E.; Holland, Joseph E.

    1989-04-04

    A system is provided to produce sugars from a liquid-solid mixture containing biomass, and an acid, wherein the mixture is heated to an appropriate temperature to achieve hydrolysis. The liquid-solid mixture is introduced as a stream into the circular-cylindrical chamber of a cyclone reaction vessel and steam is introduced to the vessel to provide the necessary heat for hydrolysis as well as to establish the liquid-solid mixture in a rotary flow field whereby the liquids and solids of the mixture move along spiral paths within the chamber. The liquid-solid mixture may be introduced at the periphery of the chamber to spiral down toward and be discharged at or near the center of the chamber. Because of differing mass, the solid particles in the mixture move radially inward at a different rate than the liquid and that rate is controlled to maximize the hydrolysis of the solids and to minimize the decomposition of sugars, thus formed.

  4. The synoptic-scale evolution during the extratropical transition of Irene (2011), Sandy (2012), and Andrea (2013)

    Science.gov (United States)

    Towey, Katherine Lorraine

    Tropical cyclones (TCs) of varying shapes, sizes, and intensities form in nearly every ocean basin and can potentially impact heavily populated areas, threatening human life and property. As a TC moves poleward, it can interact with a variety of synoptic-scale features, which results in either the dissipation of the TC or a transition into an extratropical cyclone (EXTC) through the process of extratropical transition (ET). Given an ideal synoptic-scale setup, a TC can transition into a fast-moving and rapidly developing EXTC, which could extend TC-like conditions such as strong surface winds and intense rainfall over a broad area at high latitudes. In recent years, three TCs, Irene (2011), Sandy (2012), and Andrea (2013), transitioned to EXTCs while approaching the middle latitudes and subsequently impacted the Northeast as EXTCs. In order to analyze the ET of these TCs, the cyclone phase space, developed by Hart (2003), was utilized. This product aids in determining the structural evolution associated with ET in which a symmetric, warm-core TC transitions to an asymmetric, cold-core EXTC. Changes in the structure, motion, and intensity of TCs during ET are highly dependent on the midlatitude environment into which the TC moves. A variety of factors contribute to the intensity of the resultant EXTC, including xix the overall large-scale pattern, track of the TC, time of year, as well as the intensity of the TC and the frontal system with which the TC interacts. Synoptic-scale features were analyzed for three phases of evolution throughout the ET process: tropical phase, transition period, and post-tropical phase. The TCs were not influenced by the upper-level flow until shortly after the onset of transition. It was not until the mid-way point of the transition period when the TC circulation was incorporated into the flow and began to exhibit baroclinic features. Due to differing tracks and TC intensities, the synoptic-scale features analyzed in each phase vary

  5. A weather analysis system for the Baja California peninsula: tropical cyclone season of 2007

    Science.gov (United States)

    Farfan, L. M.; Cosio, M. A.

    2008-05-01

    General characteristics of tropical weather systems were documented on a real-time basis. The geographical area of interest is the Baja California peninsula, located in northwestern Mexico. This study covers the warm season of 2007, from May through October, and includes observations derived from radar and satellite imagery as well as reports from a network of rain gauges. A set of graphical products were generated and they were available to the public through the internet. The analysis system has been in operation since the summer of 2005 and it is focused to document the development of tropical cyclones in eastern Pacific Ocean. During the season of 2007, this basin had a total of 11 tropical storms and four of them were within 800 km from the west coast of Mexico (Dalila, Ivo, Juliette and Kiko). Only one system made landfall in the area of interest: Hurricane Henriette which moved across Baja California, the Gulf of California and a portion of the state of Sonora. This presentation provides an overview of the graphical products along with lessons learned from the season studied, collaborations with local emergency managers and plans for the upcoming season of 2008.

  6. Remote Sensing of Tropical Cyclones: Applications from Microwave Radiometry and Global Navigation Satellite System Reflectometry

    Science.gov (United States)

    Morris, Mary

    Tropical cyclones (TCs) are important to observe, especially over the course of their lifetimes, most of which is spent over the ocean. Very few in situ observations are available. Remote sensing has afforded researchers and forecasters the ability to observe and understand TCs better. Every remote sensing platform used to observe TCs has benefits and disadvantages. Some remote sensing instruments are more sensitive to clouds, precipitation, and other atmospheric constituents. Some remote sensing instruments are insensitive to the atmosphere, which allows for unobstructed observations of the ocean surface. Observations of the ocean surface, either of surface roughness or emission can be used to estimate ocean surface wind speed. Estimates of surface wind speed can help determine the intensity, structure, and destructive potential of TCs. While there are many methods by which TCs are observed, this thesis focuses on two main types of remote sensing techniques: passive microwave radiometry and Global Navigation Satellite System reflectometry (GNSS-R). First, we develop and apply a rain rate and ocean surface wind speed retrieval algorithm for the Hurricane Imaging Radiometer (HIRAD). HIRAD, an airborne passive microwave radiometer, operates at C-band frequencies, and is sensitive to rain absorption and emission, as well as ocean surface emission. Motivated by the unique observing geometry and high gradient rain scenes that HIRAD typically observes, a more robust rain rate and wind speed retrieval algorithm is developed. HIRAD's observing geometry must be accounted for in the forward model and retrieval algorithm, if high rain gradients are to be estimated from HIRAD's observations, with the ultimate goal of improving surface wind speed estimation. Lastly, TC science data products are developed for the Cyclone Global Navigation Satellite System (CYGNSS). The CYGNSS constellation employs GNSS-R techniques to estimate ocean surface wind speed in all precipitating

  7. Impact of Climate Change on the Climatology of Vb Cyclones

    Science.gov (United States)

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

    2017-04-01

    Extra-tropical cyclones of type Vb develop over the western Mediterranean and move northeastward, leading to heavy precipitation over Central Europe and posing a major natural hazard. Since such cyclones are high-impact events that lead to important economical and personal damage, in Central Europe, and especially in the Alpine region, understanding their sensitivity to climate change is important to provide suitable adaptation measures. This communication aims at investigating the impact of climate change in Vb cyclones through a climate simulation covering the whole 21st century performed with the Community Earth System Model (CESM1). Further, some selected Vb episodes within the simulation are downscaled with the Weather Research and Forecasting Model (WRF). The analysis focuses on two different time periods. The reference period spans the ERA-Interim period 1979 to 2013, whereas the other one covers the last 30 years of the 21st century 2070-2099. The simulation uses the emissions from the business as usual scenario (RCP8.5). For both periods, the Vb cyclones were identified using a tracking tool and their main properties were characterized. During the reference period 86 Vb cyclones can be identified overall, which corresponds to approximately 2.5 Vb cyclones per year. This number corresponds very well to the 82 Vb cyclones found in the ERA-Interim reanalysis dataset in the same period of time. This number is reduced under future climate conditions, leading to 48 Vb cyclones in total, or to 1.6 Vb cyclones per year on average. Despite the reduction in their number, results indicate that there is a tendency for intensification in precipitation for high-impact Vb events of around 10% over the Alpine region in the future compared to the ones between 1979 and 2013. Interestingly, while the summer months are most prone for the occurrence of the 10 heaviest precipitation Vb events in the current conditions, the 10 heaviest precipitation Vb events in the future

  8. Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system.

    Science.gov (United States)

    Lim, Yun Hui; Ngo, Khanh Quoc; Park, Young Koo; Jo, Young Min

    2012-08-01

    Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume ofdust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 microm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.

  9. Cyclone and after...

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    been described with reference to a series of satellite imageries. The role of cyclone detection radar network in detection of cyclone and their use in early warning have been described with reference to radar pictures of some typical cyclones...

  10. Statistical Analysis of Ensemble Forecasts of Tropical Cyclone Tracks over the North Atlantic

    Science.gov (United States)

    2012-06-01

    generally best suited for the extratropics such that no special perturbations are applied specific to individual tropical cyclones ( UCAR 2012...Available from http://edocs.nps.edu/]. 63 UCAR , cited 2012: Guide to GFS Ensemble Track Plots. [Available online at http://www.ral.ucar.edu/guidance

  11. Development of an Expert System Based on the Systematic Approach To Tropical Cyclone Track Forecasting

    Science.gov (United States)

    2016-06-07

    The conceptual methodology for accomplishing these goals is the Systematic Approach to Tropical Cyclone Track Forecasting (hereafter Systematic...and Elsberry (1999) is shown in Table 1, and includes some significant changes compared to the preliminary result shown in last year’s report. An

  12. Characteristics of cyclones causing extreme sea levels in the northern Baltic Sea** The study was supported by the Estonian Ministry of Education and Research (IUT20-11 and Grant ETF9134 and by the EU Regional Development Foundation, Environmental Conservation and Environmental Technology R&D Programme Project No. 3.2.0801.12-0044.

    Directory of Open Access Journals (Sweden)

    Piia Post

    2014-01-01

    Full Text Available The basic parameters of extra-tropical cyclones in the northern Baltic are examined in relation to extreme sea level events at Estonian coastal stations between 1948 and 2010. The hypothesis that extreme sea level events might be caused not by one intense extra-tropical cyclone, as suggested by earlier researchers, but by the temporal clustering of cyclones in a certain trajectory corridor, is tested. More detailed analysis of atmospheric conditions at the time of the two most extreme cases support this concept: the sequence of 5 cyclones building up the extreme sea level within about 10 days was very similar in structure and periodicity.

  13. The Improved NRL Tropical Cyclone Monitoring System with a Unified Microwave Brightness Temperature Calibration Scheme

    Directory of Open Access Journals (Sweden)

    Song Yang

    2014-05-01

    Full Text Available The near real-time NRL global tropical cyclone (TC monitoring system based on multiple satellite passive microwave (PMW sensors is improved with a new inter-sensor calibration scheme to correct the biases caused by differences in these sensor’s high frequency channels. Since the PMW sensor 89 GHz channel is used in multiple current and near future operational and research satellites, a unified scheme to calibrate all satellite PMW sensor’s ice scattering channels to a common 89 GHz is created so that their brightness temperatures (TBs will be consistent and permit more accurate manual and automated analyses. In order to develop a physically consistent calibration scheme, cloud resolving model simulations of a squall line system over the west Pacific coast and hurricane Bonnie in the Atlantic Ocean are applied to simulate the views from different PMW sensors. To clarify the complicated TB biases due to the competing nature of scattering and emission effects, a four-cloud based calibration scheme is developed (rain, non-rain, light rain, and cloudy. This new physically consistent inter-sensor calibration scheme is then evaluated with the synthetic TBs of hurricane Bonnie and a squall line as well as observed TCs. Results demonstrate the large TB biases up to 13 K for heavy rain situations before calibration between TMI and AMSR-E are reduced to less than 3 K after calibration. The comparison stats show that the overall bias and RMSE are reduced by 74% and 66% for hurricane Bonnie, and 98% and 85% for squall lines, respectively. For the observed hurricane Igor, the bias and RMSE decrease 41% and 25% respectively. This study demonstrates the importance of TB calibrations between PMW sensors in order to systematically monitor the global TC life cycles in terms of intensity, inner core structure and convective organization. A physics-based calibration scheme on TC’s TB corrections developed in this study is able to significantly reduce the

  14. Concept for a cyclonic spray scrubber as a fission product removal system for filtered containment venting

    Energy Technology Data Exchange (ETDEWEB)

    Lebel, Luke S., E-mail: Luke.Lebel@cnl.ca; Piro, Markus H., E-mail: Markus.Piro@cnl.ca; MacCoy, Reilly, E-mail: Reilly.MacCoy@cnl.ca; Clouthier, Anthony, E-mail: Tony.Clouthier@cnl.ca; Chin, Yu-Shan, E-mail: Sammy.Chin@cnl.ca

    2016-02-15

    Graphical abstract: - Highlights: • A new cyclonic spray scrubber concept for filtered containment venting is presented. • Mechanistic particle removal model paired with discrete particle CFD simulations. • Calculations predict that very high decontamination factors can be achieved. - Abstract: The application of a cyclonic spray scrubber as a technology for filtered containment venting is proposed in this paper. This study has paired a mechanistic model for the kinetic particle coagulation of with Euler–Lagrange discrete particle simulations in order to predict particle decontamination factors. The continuous phase behavior has been investigated using computational fluid dynamics simulations together with phase Doppler anemometry measurements. Calculations show that spray scrubbing of radionuclide-bearing aerosols could be very effective, and predict that decontamination factors can be in excess of 10{sup 6} for micron sized particles and excess of 10{sup 3} for submicron particles. In the wake of the accident at the Fukushima Daiichi Nuclear Power Plant, filtered containment venting is being viewed as an increasingly important severe accident mitigation technology. Cyclonic spray scrubbing could be implemented as a passive technology for decontaminating containment gases in an emergency prior to their discharge to the atmosphere, and is a novel approach for this application.

  15. Desarrollo de aplicaciones basadas en Linux Embedded en una arquitectura basada en Cyclone V SoC (System on Chip) de Altera

    OpenAIRE

    2014-01-01

    We attempt to integrate and start up the set of necessary tools to deploy the design cycle of embedded systems based on Embedded Linux on a "Cyclone V SoC" made by Altera. First, we will analyze the available tools for designing the hardware system of the SoCkit development kit, made by Arrow, which has a "Cyclone V SoC" system (based on a "ARM Cortex-A9 MP Core" architecture). When designing the SoCkit board hardware, we will create a new peripheral to integrate it into the hardware syste...

  16. Tropical Cyclone Report, 1988

    Science.gov (United States)

    1988-01-01

    TAIWAN NAVPGSCOL LIBRARY CITIES SERVICES OIL GAS CORP NAVPOLAROCEANCEN SUITLAND CIUDAD UNIVERSITARIA , MEXICO NAVAL RESEARCH LAB CIVIL DEFENSE, SAIPAN...The system software has been provided An effort is now underway to develop a to OAO Corporation for inclusion in the JTWC series of examples...winds in the range of 34 to speed, typically within one degree of the center of a 63 kt (17 to 32 m/sec) inclusive . tropical cyclone. TROPICAL UPPER

  17. A coupled atmosphere-ocean-wave modeling approach for a Tropical Like Cyclone in the Mediterranean Sea

    Science.gov (United States)

    Ricchi, Antonio; Miglietta, M. Marcello; Barbariol, Francesco; Benetazzo, Alvise; Bonaldo, Davide; Falcieri, Francesco; Russo, Aniello; Sclavo, Mauro; Carniel, Sandro

    2016-04-01

    In November 6-8, 2011, in the Balearic islands an extra-tropical depression developed into a Tropical-Like Cyclone (TLC) characterized by a deep-warm core, leading to a mean sea level pressure minimum of about 991 hPa, 10 m wind speeds higher than 28 m/s around the eye, and very intense rainfall, especially in the Gulf of Lion. To explore in detail the effect of the sea surface temperature on the Medicane evolution, we employed the coupled modeling system COAWST, which consists of the ROMS model for the hydrodynamic part, the WRF model for the meteorological part, and the SWAN for the surface wave modeling. All model run over 5 km domain (same domain for ROMS and SWAN). COAWST was used with different configurations: in Stand Alone (SA) mode (that is, with only the atmospheric part), in atmosphere-ocean coupled mode (AO), and in a fully coupled version including also surface waves (AOW). Several sensitivity simulations performed with the SA approach were undertaken to simulate the TLC evolution. Especially in the later stage of the lifetime, when the cyclone was weaker, the predictability appears limited. Sensitivity simulations have considered the effect of the cumulus scheme (using an explicit scheme the Medicane does not develop and remains an extra-tropical depression) and the PBL scheme (using MYJ or MYNN resulting "Medicane" are extremely similar, although the roughness appears rather different among the two experiments). Comparing the three runs, the effects of different simulations on the Medicane tracks are significant only in the later stage of the cyclone lifetime. In the overall modeled basin, wind intensity is higher in the SA case w.r.t. both coupled runs. When compared to case AO, winds are about 1 m/s larger, even though the spatial distribution is very similar (possibly because of the lower SST produced by case AO). Case AOW produces less intense winds then SA and AO case in the areas where the wave is most developed (differences are about 2-4 m

  18. An error analysis of tropical cyclone divergence and vorticity fields derived from satellite cloud winds on the Atmospheric and Oceanographic Information Processing System (AOIPS)

    Science.gov (United States)

    Hasler, A. F.; Rodgers, E. B.

    1977-01-01

    An advanced Man-Interactive image and data processing system (AOIPS) was developed to extract basic meteorological parameters from satellite data and to perform further analyses. The errors in the satellite derived cloud wind fields for tropical cyclones are investigated. The propagation of these errors through the AOIPS system and their effects on the analysis of horizontal divergence and relative vorticity are evaluated.

  19. Tropical Cyclone Prediction Using COAMPS-TC

    Science.gov (United States)

    2014-09-01

    Oceanography | Vol. 27, No.3104 S P E C I A L I S S U E O N N AV Y O P E R AT I O N A L M O D E L S Tropical Cyclone Prediction Using COAMPS...Ocean/ Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS®-TC) has been developed for prediction of tropical cyclone track, structure...and intensity. The COAMPS-TC has been tested in real time in both uncoupled and coupled modes over the past several tropical cyclone seasons in

  20. Scenarios in the development of Mediterranean cyclones

    Directory of Open Access Journals (Sweden)

    M. Romem

    2007-07-01

    Full Text Available The Mediterranean is one of the most cyclogenetic regions in the world. The cyclones are concentrated along its northern coasts and their tracks are oriented more or less west-east, with several secondary tracks connecting them to Europe and to North Africa. The aim of this study is to examine scenarios in the development of Mediterranean cyclones, based on five selected winter seasons (October–March. We detected the cyclones subjectively using 6-hourly Sea-Level Pressure maps, based on the NCAR/NCEP reanalysis archive.

    HMSO (1962 has shown that most Mediterranean cyclones (58% enter the Mediterranean from the Atlantic Ocean (through Biscay and Gibraltar, and from the south-west, the Sahara Desert, while the rest are formed in the Mediterranean Basin itself. Our study revealed that only 13% of the cyclones entered the Mediterranean, while 87% were generated in the Mediterranean Basin. The entering cyclones originate in three different regions: the Sahara Desert (6%, the Atlantic Ocean (4%, and Western Europe (3%.

    The cyclones formed within the Mediterranean Basin were found to generate under the influence of external cyclonic systems, i.e. as "daughter cyclones" to "parent cyclones" or troughs. These parent systems are located in three regions: Europe (61%, North Africa and the Red Sea (34.5% and the Mediterranean Basin itself (4.5%. The study presents scenarios in the development of Mediterranean cyclones during the winter season, emphasizing the cyclogenesis under the influence of various external forcing.

    The large difference with respect to the findings of HMSO (1962 is partly explained by the dominance of spring cyclones generating in the Sahara Desert, especially in April and May that were not included in our study period.

  1. The spatial distribution and evolution characteristics of North Atlantic cyclones

    Science.gov (United States)

    Dacre, H.; Gray, S.

    2009-09-01

    Mid-latitude cyclones play a large role in determining the day-to-day weather conditions in western Europe through their associated wind and precipitation patterns. Thus, their typical spatial and evolution characteristics are of great interest to meteorologists, insurance and risk management companies. In this study a feature tracking algorithm is applied to a cyclone database produced using the Hewson-method of cyclone identification, based on low-level gradients of wet-bulb potential temperature, to produce a climatology of mid-latitude cyclones. The aim of this work is to compare the cyclone track and density statistics found in this study with previous climatologies and to determine reasons for any differences. This method is found to compare well with other cyclone identification methods; the north Atlantic storm track is reproduced along with the major regions of genesis. Differences are attributed to cyclone lifetime and strength thresholds, dataset resolution and cyclone identification and tracking methods. Previous work on cyclone development has been largely limited to case studies as opposed to analysis of climatological data, and does not distinguish between the different stages of cyclone evolution. The cyclone database used in this study allows cyclone characteristics to be tracked throughout the cyclone lifecycle. This enables the evaluation of the characteristics of cyclone evolution for systems forming in different genesis regions and a calculation of the spatial distribution and evolution of these characteristics in composite cyclones. It was found that most of the cyclones that cross western Europe originate in the east Atlantic where the baroclinicity and sea surface temperature gradients are weak compared to the west Atlantic. East Atlantic cyclones also have higher low-level relative vorticity and lower mean sea level pressure at their genesis point than west Atlantic cyclones. This is consistent with the hypothesis that they are secondary

  2. Objective climatology of cyclones in the Mediterranean region: a consensus view among methods with different system identification and tracking criteria

    Directory of Open Access Journals (Sweden)

    Piero Lionello

    2016-05-01

    Full Text Available The Mediterranean storm track constitutes a well-defined branch of the North Hemisphere storm track and is characterised by small but intense features and frequent cyclogenesis. The goal of this study is to assess the level of consensus among cyclone detection and tracking methods (CDTMs, to identify robust features and to explore sources of disagreement. A set of 14 CDTMs has been applied for computing the climatology of cyclones crossing the Mediterranean region using the ERA-Interim dataset for the period 1979–2008 as common testbed. Results show large differences in actual cyclone numbers identified by different methods, but a good level of consensus on the interpretation of results regarding location, annual cycle and trends of cyclone tracks. Cyclogenesis areas such as the north-western Mediterranean, North Africa, north shore of the Levantine basin, as well as the seasonality of their maxima are robust features on which methods show a substantial agreement. Differences among methods are greatly reduced if cyclone numbers are transformed to a dimensionless index, which, in spite of disagreement on mean values and interannual variances of cyclone numbers, reveals a consensus on variability, sign and significance of trends. Further, excluding ‘weak’ and ‘slow’ cyclones from the computation of cyclone statistics improves the agreement among CDTMs. Results show significant negative trends of cyclone frequency in spring and positive trends in summer, whose contrasting effects compensate each other at annual scale, so that there is no significant long-term trend in total cyclone numbers in the Mediterranean basin in the 1979–2008 period.

  3. Polytropic process and tropical Cyclones

    CERN Document Server

    Romanelli, Alejandro; Rodríguez, Juan

    2013-01-01

    We show a parallelism between the expansion and compression of the atmosphere in the secondary cycle of a tropical cyclone with the fast expansion and compression of wet air in a bottle. We present a simple model in order to understand how the system (cyclone) draws energy from the air humidity. In particular we suggest that the upward (downward) expansion (compression) of the warm (cold) moist (dry) air follows a polytropic process, $PV^\\beta$= constant. We show both experimentally and analytically that $\\beta$ depends on the initial vapor pressure in the air. We propose that the adiabatic stages in the Carnot-cycle model for the tropical cyclone be replaced by two polytropic stages. These polytropic processes can explain how the wind wins energy and how the rain and the dry bands are produced inside the storm.

  4. Tropical Cyclones as a Critical Phenomenon

    CERN Document Server

    Corral, A

    2011-01-01

    It has been proposed that the number of tropical cyclones as a function of the energy they release is a decreasing power-law function, up to a characteristic energy cutoff determined by the spatial size of the ocean basin in which the storm occurs. This means that no characteristic scale exists for the energy of tropical cyclones, except for the finite-size effects induced by the boundaries of the basins. This has important implications for the physics of tropical cyclones. We discuss up to what point tropical cyclones are related to critical phenomena (in the same way as earthquakes, rainfall, etc.), providing a consistent picture of the energy balance in the system. Moreover, this perspective allows one to visualize more clearly the effects of global warming on tropical-cyclone occurrence.

  5. A study of simulation and prediction of extratropical cyclones over the Northern Hemisphere partⅡ:Future changes under RCP4.5 projected by the 6 CMIP5 coupled models%北半球温带气旋的模拟和预估研究Ⅱ∶6个 CMIP5耦合模式预估的未来 RCP4.5情景下的变化

    Institute of Scientific and Technical Information of China (English)

    张颖娴; 丁一汇

    2014-01-01

    The simulation results of the 6 climate coupled models of CMIP5 under the secondary emission scenarion RCP4.5 (Representative Concentration Pathway 4.5)are used to estimate the changes of the extratropical cyclone (EC)numbers and EC intensity,as well as the storm track and its strength in the future.The results indicate that:(1)although each model dif¯ fers in the simulations of the regional cyclogenesis during 2053—2100 under RCP4.5 relative to the second half of the 20th cen¯ tury,it is similarly found that ECs would decrease integrally in the Northern Hemisphere,especially in the lower latitudes.(2) The central pressure of ECs over the Northern Hemisphere would depress and the vorticity intensity would weaken in the future reproduced by models consistently.The simulated Atlantic storm track would move polewards sequentially but with weakened strength as are shown by most of the models in the future;the simulated Pacific storm track would also migrate polewards by more than half the models,but with intensity changes differing in the different seasons.And,(3)a poleward movement of the future baroclinic zone in the middle¯upper troposphere is detected in all the 6 models,and this change in the Southern Hemi¯ sphere would be more significant.The changes of the baroclinic zone reflect the similar changes of storm track to some extent, which supports for the conclusion of possible poleward shift of the two storm tracks.That could be a significant reduction in EC activities over the Northern Hemisphere under RCP4.5,while the poleward movements of baroclinic zone and storm path would cause more remarkable reduction of EC activities over the lower latitudes in the future.%利用 CMIP5(Coupled Model Intercomparison Project Phase 5)的6个气候耦合模式中等排放情景———RCP4•5(典型浓度路径4•5)下的模拟结果对北半球温带气旋数目、风暴路径和强度的未来变化进行了研究分析。结果表明:(1)相对于20

  6. The Intensity-dependence of Tropical Cyclone Intensification in a Simplified Energetic System and a Full Physics Model

    Science.gov (United States)

    Wang, Y.

    2015-12-01

    Several recent studies based on best track data for tropical cyclones (TCs) over the North Atlantic revealed a strong dependence of the TC intensification rate (IR) on TC intensity. The TC IR shows a maximum (i.e., most rapid intensification) when the TC intensity reaches about 35 - 40 m s-1. Physically, this intensity-dependence has been explained in terms of the inner-core inertial stability and the decreased potential for a TC to intensify as it approaches its maximum potential intensity (MPI). Here, we propose a new simplified dynamical system based on TC energetics. For this purpose, the TC system is considered as a Carnot heat engine as in earlier theoretical studies, and formulated on the grounds of major energy production and dissipation processes. This offers a way to explain the IR behavior of TCs in terms of its sensitivity to the physical processes involved, and to derive a physically-based relationship between TC intensification and intensity. This relationship is consistent with observations, and in quantitative agreement with that gained from empirical relations in an alternative dynamical system proposed by DeMaria(2009), which has been formulated analogously to the logistic growth equation (LGE). Results from idealized full-physics model simulations confirm the validity of several key assumptions implicitly involved in the simplified dynamical system and the intensity-dependence of the TC IR as well.

  7. Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

    OpenAIRE

    OZAWA,Hisashi; SHIMOKAWA, Shinya

    2015-01-01

    The formation process of circulatory motion of a tropical cyclone is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the first and second laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation ...

  8. A case study on the cyclone activity around Europe from winter to spring of 2000 (From the view of comparison with that in East Asia)

    Science.gov (United States)

    Kuwana, Yusuke; Otani, Kazuo; Matsumoto, Kengo; Kato, Kuranoshin

    2017-04-01

    The extratropical cyclone is one of the basic systems that characterize the weather and climate in mid-latitude area, where the mean meridional temperature gradient is large. However, this activity is deeply influenced by the seasonal transition and regional differences of the mean atmospheric fields. Diversity of cyclone's characteristics such as baroclinic instability wave, polar lows and slow-moving cold vortexes is also seen within the mid-latitude area. For example, the seasonal transition of the large-scale fields is rather widely different in European region from that in East Asia where the influence Asian monsoon is very great. It is also noted that the cyclones developed in the other region might effect greatly the weather in Europe. On the other hand, detailed knowledge of the daily cyclone activity would help to understand deeply the differences of regional climatology among various areas including seasonal transition and geographical characteristics. After such interest, Takigawa and Kato(EGU 2015) made a preliminary study on the cyclone activity in Europe . We used the NCEP/NCAR re-analysis data for 2000 and pointed out that not only the daily systems but also the intraseasonal-scale systems were also dominant in winter and summer. Thus the present study will examining the case for 2000 with special attention to the features from winter to spring. In winter, submonthly-scale intraseasonal variation of the Icelandic Low was change. In the stage when Icelandic Low with such intraseasonal-scale approached northwestern Europe, several lows passed eastward around with a few days interval the southern edge of Icelandic low with relatively strong baraclinicity. It is remarked that their center pressure was rather low (below 980hPa). After April, when the seasonal mean Icelandic low had disappeared, different types of the intra-seasonal-scale cyclones and anticyclones were dominantly observed. In the lower SLP stage of the intraseasonal variation in Europe

  9. An Observing System Simulation Experiment (OSSE to Assess the Impact of Doppler Wind Lidar (DWL Measurements on the Numerical Simulation of a Tropical Cyclone

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2010-01-01

    Full Text Available The importance of wind observations has been recognized for many years. However, wind observations—especially three-dimensional global wind measurements—are very limited. A satellite-based Doppler Wind Lidar (DWL is proposed to measure three-dimensional wind profiles using remote sensing techniques. Assimilating these observations into a mesoscale model is expected to improve the performance of the numerical weather prediction (NWP models. In order to examine the potential impact of the DWL three-dimensional wind profile observations on the numerical simulation and prediction of tropical cyclones, a set of observing simulation system experiments (OSSEs is performed using the advanced research version of the Weather Research and Forecasting (WRF model and its three-dimensional variational (3DVAR data assimilation system. Results indicate that assimilating the DWL wind observations into the mesoscale numerical model has significant potential for improving tropical cyclone track and intensity forecasts.

  10. 旋风干燥系统技术改造总结%Summary on the technical remoulding of cyclone drying system

    Institute of Scientific and Technical Information of China (English)

    田小娟; 张宇; 赵峰

    2012-01-01

    总结了悬浮法PVC装置旋风干燥系统的多项技术改造.包括气流干燥管、螺旋输送器、空气加热器、鼓风机等设备的改造,并增加了空气预热装置。改造后旋风干燥系统的生产能力得到了提高,满足了工艺要求。%Many technical remouldings related to the cyclone drying system in suspension PVC production plant were sumarized, including the remoulding of pneumatic tubes, auger conveyor, air heaters and blowing machines, and adding an air preheater. After remoulding, the production capacity of cyclone drying system were improved, and thus meeting the process requirements.

  11. Dynamics of synoptic-scale cyclones: A conceptual view based on potential vorticity building blocks and the theory of optimal perturbations

    NARCIS (Netherlands)

    Vries, Hylke de

    2006-01-01

    The development of extra-tropical cyclones has been investigated for a model hierarchy. The aim of the study was to get insight into the main mechanisms responsible for the rapid development. A physically intuitive approach in terms of potential vorticity has been invoked to construct so-called

  12. Cyclonic Separation Technology: Researches and Developments

    Institute of Scientific and Technical Information of China (English)

    汪华林; 张艳红; 王剑刚; 刘洪来

    2012-01-01

    Centered on thetechniques and industrial applications of the reinforced cyclonic separation process, its principles and mechanism for separation ot ions, molecules and their aggregates using polyalsperse aroplets are discussed generally; the characteristics and influential factors of fish-hook phenomenon of the grade efficiency curve in cyclonic separation for both gas and liquid are analyzed; and the influence of shear force on particle be- havior (or that of particle swarm) is also summarized. A novel idea for cyclonic separation is presented here: enhancing the cyclonic seoaration process of ions, molecules and their aggregates with monodisperse microspheres and their surface grafting, rearranging the distribution of particles by size using centrifugal field, reinforcing the cyclonic separation performance with orderly arranged particle swarm. Also the investigation of the shortcut flow, recirculation flow, the asymmetric structure and non-linear characteristics of the cyclonic flow field with a com-bined method of Volumetric 3-component Velocimetry (V3V) and Phase-Doppler Particle Anemometer (PDPA) are elaborated. It is recommended to develop new systems for the separation of heterogeneous phases with cyclonic technology, in accordance with the capture and reuse of CO2, methanol to olefins (MTO) process, coal transfer, andthe exploitation of oil shale.

  13. APR-2 Tropical Cyclone Observations

    Science.gov (United States)

    Durden, S. L.; Tanelli, S.

    2011-01-01

    The Second Generation Airborne Precipitation Radar (APR-2) participated in the Genesis and Rapid Intensification Processes (GRIP) experiment in August and September of 2010, collecting a large volume of data in several tropical systems, including Hurricanes Earl and Karl. Additional measurements of tropical cyclone have been made by APR-2 in experiments prior to GRIP (namely, CAMEX-4, NAMMA, TC4); Table 1 lists all the APR-2 tropical cyclone observations. The APR-2 observations consist of the vertical structure of rain reflectivity at 13.4 and 35.6 GHz, and at both co-polarization and crosspolarization, as well as vertical Doppler measurements and crosswind measurements. APR-2 normally flies on the NASA DC-8 aircraft, as in GRIP, collecting data with a downward looking, cross-track scanning geometry. The scan limits are 25 degrees on either side of the aircraft, resulting in a roughly 10-km swath, depending on the aircraft altitude. Details of the APR-2 observation geometry and performance can be found in Sadowy et al. (2003).The multiparameter nature of the APR-2 measurements makes the collection of tropical cyclone measurements valuable for detailed studies of the processes, microphysics and dynamics of tropical cyclones, as well as weaker systems that are associated with tropical cyclone formation. In this paper, we give a brief overview of how the APR-2 data are processed. We also discuss use of the APR-2 cross-track winds to estimate various quantities of interest in in studies of storm intensification. Finally, we show examples of the standard products and derived information.

  14. Emergency Department Presentations following Tropical Cyclone Yasi

    OpenAIRE

    Peter Aitken; Richard Charles Franklin; Jenine Lawlor; Rob Mitchell; Kerrianne Watt; Jeremy Furyk; Niall Small; Leone Lovegrove; Peter Leggat

    2015-01-01

    Introduction Emergency departments see an increase in cases during cyclones. The aim of this study is to describe patient presentations to the Emergency Department (ED) of a tertiary level hospital (Townsville) following a tropical cyclone (Yasi). Specific areas of focus include changes in: patient demographics (age and gender), triage categories, and classification of diseases. Methods Data were extracted from the Townsville Hospitals ED information system (EDIS) for three periods in 2009, 2...

  15. Large-Scale Weather Disturbances in Mars’ Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2015-11-01

    Between late autumn and early spring, Mars’ middle and high latitudes within its atmosphere support strong mean thermal gradients between the tropics and poles. Observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). These extratropical weather disturbances are key components of the global circulation. Such wave-like disturbances act as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively lifted and radiatively active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are examined. Simulations that adapt Mars’ full topography compared to simulations that utilize synthetic topographies emulating key large-scale features of the southern middle latitudes indicate that Mars’ transient barotropic/baroclinic eddies are highly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). The occurrence of a southern storm zone in late winter and early spring appears to be anchored to the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre

  16. Tropical response to extratropical eastward propagating waves

    Directory of Open Access Journals (Sweden)

    S. Sridharan

    2015-06-01

    Full Text Available Space–time spectral analysis of ERA-interim winds and temperature at 200 hPa for December 2012–February 2013 shows the presence of eastward propagating waves with period near 18 days in mid-latitude meridional winds at 200 hPa. The 18 day waves of k = 1–2 are dominantly present at latitudes greater than 80°, whereas the waves of k = 3–4 are dominant at 60° of both Northern and Southern Hemispheres. Though the 18 day wave of smaller zonal wavenumbers (k = 1–2 are confined to high latitudes, there is an equatorward propagation of the 18 day wave of k = 4 and 5. The wave amplitude of k = 5 is dominant than that of k = 4 at tropical latitudes. In the Northern Hemisphere (NH, there is a poleward tilt in the phase of the wave of k = 5 at mid-latitudes, as height increases indicating the baroclinic nature of the wave, whereas in the Southern Hemisphere (SH, the wave has barotropic structure as there is no significant phase variation with height. At the NH subtropics, the wave activity is confined to 500–70 hPa with moderate amplitudes. It is reported for the first time that the wave of similar periodicity (18 day and zonal structure (k = 5 as that of extratropical wave disturbance has been observed in tropical OLR, a proxy for tropical convection. We suggest that the selective response of the tropical wave forcing may be due to the lateral forcing of the eastward propagating extratropical wave of similar periodicity and zonal structure.

  17. The effect of the dust collection system on the flowpattern and separation efficiency of a gas cyclone

    NARCIS (Netherlands)

    Hoffmann, A.C; deGroot, M.; Hospers, A.

    1996-01-01

    The influence of the presence of a hopper section, consisting of a dust hopper and swirl attenuator, under gas-solid cyclones has been investigated by numerical simulation. Inclusion of this configuration in the simulations was found to have a significant influence on both flowpattern and separation

  18. Variant for estimating the activity of tropical cyclone groups in the world ocean

    Science.gov (United States)

    Yaroshevich, M. I.

    2016-12-01

    It is especially important to know the character and the intensity level of tropical cyclone (TC) activity when the system for estimating the cyclonic danger and risk is formed. During seasons of increased cyclonic activity, when several TCs are simultaneously active, the total energy effect of the cyclone group joint action is not estimated numerically. Cyclonic activity is as a rule characterized by the number of TCs that occur in the considered zone. A variant of the criterion, according to which relative cyclonic activity is estimated, is presented.

  19. Multiscale asymptotics for the Skeleton of the Madden-Julian Oscillation and Tropical-Extratropical Interactions

    CERN Document Server

    Chen, Shengqian; Stechmann, Samuel N

    2015-01-01

    A new model is derived and analyzed for tropical-extratropical interactions involving the Madden-Julian oscillation (MJO). The model combines (i) the tropical dynamics of the MJO and equatorial baroclinic waves and (ii) the dynamics of barotropic Rossby waves with significant extratropical structure, and the combined system has a conserved energy. The method of multiscale asymptotics is applied to systematically derive a system of ordinary differential equations (ODEs) for three-wave resonant interactions. Two novel features are (i) a degenerate auxiliary problem with overdetermined equations due to a compatibility condition (meridional geostrophic balance) and (ii) cubic self-interaction terms that are not typically found in three-wave resonance ODEs. Several examples illustrate applications to MJO initiation and termination, including cases of (i) the MJO, equatorial baroclinic Rossby waves, and barotropic Rossby waves interacting, and (ii) the MJO, baroclinic Kelvin waves, and barotropic Rossby waves inter...

  20. Sensitivity of Cyclone Tracks to the Initial Moisture Distribution: A Moist Potential Vorticity Perspective

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In this study, the characteristics of moist potential vorticity (MPV) in the vicinity of a surface cyclone center and their physical processes are investigated. A prognostic equation of surface absolute vorticity is then used to examine the relationship between the cyclone tracks and negative MPV (NMPV) using numerical simulations of the life cycle of an extratropical cyclone. It is shown that the MPV approach developed herein, i.e., by tracing the peak NMPV, can be used to help trace surface cyclones during their development and mature stages. Sensitivity experiments are conducted to investigate the impact of different initial moisture fields on the effectiveness of the MPV approach. It is found that the lifetime of NMPV depends mainly on the initial moisture field, the magnitude of condensational heating, and the advection of NMPV. When NMPV moves into a saturated environment at or near a cyclone center, it can trace better the evolution of the surface cyclone due to the conservative property of MPV. It is also shown that the NMPV generation is closely associated with the coupling of large potential temperature and moisture gradients as a result of frontogenesis processes. Analyses indicate that condensation, confluence and tilting play important but different roles in determining the NMPV generation. NMPV is generated mainly through the changes in the strength of baroclinicity and in the direction of the moisture gradient due to moist and/or dry air mass intrusion into the baroclinic zone.

  1. Development of a software and hardware system for monitoring the air cleaning process using a cyclone-separator

    Science.gov (United States)

    Nicolaeva, B. K.; Borisov, A. P.; Zlochevskiy, V. L.

    2017-08-01

    The article is devoted to the development of a hardware-software complex for monitoring and controlling the process of air purification by means of a cyclone-separator. The hardware of this complex is the Arduino platform, to which are connected pressure sensors, air velocities, dustmeters, which allow monitoring of the main parameters of the cyclone-separator. Also, a frequency converter was developed to regulate the rotation speed of an asynchronous motor necessary to correct the flow rate, the control signals of which come with Arduino. The program part of the complex is written in the form of a web application in the programming language JavaScript and inserts into CSS and HTML for the user interface. This program allows you to receive data from sensors, build dependencies in real time and control the speed of rotation of an asynchronous electric drive. The conducted experiment shows that the cleaning efficiency is 95-99.9%, while the airflow at the cyclone inlet is 16-18 m/s, and at the exit 50-70 m/s.

  2. Exploring alternative wind vulnerability and loss modeling methods - application to Europe extra-tropical cyclones

    Science.gov (United States)

    Peiris, N.

    2009-04-01

    Catastrophe models are used to assess the economic and insured loss to the built environment due to natural hazards such as earthquakes, windstorms, floods, storm surges, tsunamis, etc. A conventional catastrophe model estimating direct economic loss could be divided into three basic components; hazard, vulnerability and exposure. For a single event, the hazard component represents the best estimate realization of the hazard footprint over a region at the modeling resolution, i.e. variable grid, postalcode, cresta, etc. The vulnerability component represents the response of the buildings or any modeled structure to the hazard, quantified in terms of a loss ratio. The exposure component represents the value of the buildings in a portfolio covering a region or those underwritten by an insurer or a re-insurer. The exposure together with the vulnerability functions produces the expected economic loss of the hazard footprint for a given hazard event. In the case of estimating indirect economic losses and insured losses financial models are utilized with various financial structures applied on the economic loss estimates. The commonly used method of characterizing wind vulnerability of buildings is to develop functions of mean loss ratio or mean damage ratio (MDR) vs wind speed where the wind speed is often defined as the peak gust measured at a height of 10m above the ground elevation. The uncertainty associated with MDR due to the likelihood of the building experiencing a range of damage states and hence loss ratios at a given wind speed is quantified by a continuous statistical distribution with a mean (which is the MDR) and a standard deviation, SD. For a given event footprint a conventional catastrophe model calculates an MDR and associated SD for each location of a building portfolio. This together with the location exposure or insured value results in the location loss. The location losses are then aggregated together with their SDs to obtain the total expected loss over the event footprint and the associated uncertainty. Now, the actual loss in the building portfolio may not occur at every location, i.e. there are locations with and without loss. It is anticipated that the total incurred loss over the footprint falls within the range of modeled footprint loss and closer to the expected modeled loss value. An alternative methodology to the above was explored where it was attempted to model realizations of actual losses expected at each location. Firstly the building vulnerability was represented by its underlying fragility functions where each fragility function characterizes the likely damage mode and hence the loss ratio the building could experience during a windstorm and the associated probability of occurrence conditional on the wind speed. The damage modes considered are mutually exclusive and engineering considerations determine the extent of correlation between each damage mode (or sub-damage state). The fragility functions therefore describe the damage matrix for a building subjected to the wind hazard and this matrix produces the probability of damage as well as no damage. Hence at a building location subjected to a certain wind speed within the hazard footprint, one could sample from the damage matrix the actual damage ratio, which could range from zero (where no damage could occur) to the maximum likely damage ratio. By sampling all locations N times, one could subsequently obtain N realizations of the loss footprint hence obtain the expected total event loss and the loss distribution quantifying the uncertainty. In evaluating the insured loss or gross loss, the calculated ground-up loss at a location is used in the expected mode to estimate the gross loss based on the deductibles, limits and other relevant financial structures. This is in contrast to the conventional catastrophe model where the gross loss is calculated as a distributed loss using MDR and SD. The location correlation modeling was explored in the alternative methodology using correlated sampling techniques and compared with the methodology in

  3. The downstream response to explosive extratropical cyclone intensification over the North Pacific

    Science.gov (United States)

    Lupo, Kevin Michael

    The elastohydrodynamic lubrication (EHL) regime is characterized by the elastic deformation of the bodies in contact, hydrodynamics of viscous friction caused by shearing the lubricant, and dramatic viscosity increase due to high pressure. As technology for mechanical components advances towards higher energy efficiency and less energy loss from viscous friction, this advancement implies that lubricant films are decreasing towards thicknesses on the nanometer scale. However, these lubricant films may behave differently from what is predicted by classical EHL theory. While viscosity is affected by temperature, pressure, and shear rate, researchers have discovered that there is a new dependence of film thickness on viscosity, indicating that extreme confinement in EHL can affect the viscosity of the lubricant. In this work, we attempt to characterize the relationship between film thickness and viscosity for squalane using molecular dynamics (MD) simulations so that we may observe how the lubricant behaves with film thicknesses on the nanometer scale. However, we were unable to successfully obtain this relationship due to issues with the MD simulations. In addition, we attempt to improve the ability of EHL simulations to accurately capture the behavior of ultra-thin film lubricated interfaces by incorporating empirical models that describe the effect of confinement on fluid viscosity. The enhanced model reproduces trends seen in some EHL experiments where the film thickness of very thin film lubricants is larger than expected compared to classical EHL theory. Our enhanced EHL simulation successfully produces film thickness results with increased accuracy to experimental data.

  4. A Linear Stability Analysis of the Rapid Development of an Extratropical Cyclone.

    Science.gov (United States)

    1986-03-01

    temperatura perturbation(i 91 . • w +I. 0. .040HORIZONTRL DISTRNCE (X IOE2 KM) 100 5.0 5.0 10.0 12.0 14.0 16. z . w200 oZ •L 400 -" 0 500 .- =100 700...Tucson, Arizona 85721 27. Lynn K. Shay (Code 63Sh) 1 Department of Met rolo Monterey, Ca. 939-58 110 .’ .’ *. mmt 28. William Clune 1 Quality Control

  5. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  6. Grey swan tropical cyclones

    Science.gov (United States)

    Lin, Ning; Emanuel, Kerry

    2016-01-01

    We define `grey swan’ tropical cyclones as high-impact storms that would not be predicted based on history but may be foreseeable using physical knowledge together with historical data. Here we apply a climatological-hydrodynamic method to estimate grey swan tropical cyclone storm surge threat for three highly vulnerable coastal regions. We identify a potentially large risk in the Persian Gulf, where tropical cyclones have never been recorded, and larger-than-expected threats in Cairns, Australia, and Tampa, Florida. Grey swan tropical cyclones striking Tampa, Cairns and Dubai can generate storm surges of about 6 m, 5.7 m and 4 m, respectively, with estimated annual exceedance probabilities of about 1/10,000. With climate change, these probabilities can increase significantly over the twenty-first century (to 1/3,100-1/1,100 in the middle and 1/2,500-1/700 towards the end of the century for Tampa). Worse grey swan tropical cyclones, inducing surges exceeding 11 m in Tampa and 7 m in Dubai, are also revealed with non-negligible probabilities, especially towards the end of the century.

  7. Cyclone reduction of taconite. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, P.R.; Bartlett, R.W.; Abdel-latif, M.A.; Hou, X.; Kumar, P. [College of Mines and Earth Resources, University of Idaho, Idaho Falls, ID (United States)

    1995-05-01

    A cyclone reactor system for the partial reduction and melting of taconite concentrate fines has been engineered, designed and operated. A non-transferred arc plasma torch was employed as a heat source. Taconite fines, carbon monoxide, and carbon dioxide were fed axially into the reactor, while the plasma gas was introduced tangentially into the cyclone. The average reactor temperature was maintained at above 1400{degrees}C, and reduction experiments were performed under various conditions. The influence of the following parameters on the reduction of taconite was investigated experimentally; carbon monoxide to carbon dioxide inlet feed ratio, carbon monoxide inlet partial pressure, and average reactor temperature. The interactions of the graphite lining with carbon dioxide and taconite were also studied. An attempt was made to characterize the flow behavior of the molten product within the cyclone. The results suggest that the system may approach a plug flow reactor, with little back mixing. Finally, a fundamental mathematical model was developed. The model describes the flow dynamics of gases and solid particles in a cyclone reactor, energy exchange, mass transfer, and the chemical kinetics associated with cyclone smelting of taconite concentrate fines. The influence of the various parameters on the reduction and melting of taconite particles was evaluated theoretically.

  8. Human-induced greening of the northern extratropical land surface

    Science.gov (United States)

    Mao, Jiafu; Ribes, Aurélien; Yan, Binyan; Shi, Xiaoying; Thornton, Peter E.; Séférian, Roland; Ciais, Philippe; Myneni, Ranga B.; Douville, Hervé; Piao, Shilong; Zhu, Zaichun; Dickinson, Robert E.; Dai, Yongjiu; Ricciuto, Daniel M.; Jin, Mingzhou; Hoffman, Forrest M.; Wang, Bin; Huang, Mengtian; Lian, Xu

    2016-10-01

    Significant land greening in the northern extratropical latitudes (NEL) has been documented through satellite observations during the past three decades. This enhanced vegetation growth has broad implications for surface energy, water and carbon budgets, and ecosystem services across multiple scales. Discernible human impacts on the Earth's climate system have been revealed by using statistical frameworks of detection-attribution. These impacts, however, were not previously identified on the NEL greening signal, owing to the lack of long-term observational records, possible bias of satellite data, different algorithms used to calculate vegetation greenness, and the lack of suitable simulations from coupled Earth system models (ESMs). Here we have overcome these challenges to attribute recent changes in NEL vegetation activity. We used two 30-year-long remote-sensing-based leaf area index (LAI) data sets, simulations from 19 coupled ESMs with interactive vegetation, and a formal detection and attribution algorithm. Our findings reveal that the observed greening record is consistent with an assumption of anthropogenic forcings, where greenhouse gases play a dominant role, but is not consistent with simulations that include only natural forcings and internal climate variability. These results provide the first clear evidence of a discernible human fingerprint on physiological vegetation changes other than phenology and range shifts.

  9. Observational Analysis of Cloud and Precipitation in Midlatitude Cyclones: Northern Versus Southern Hemisphere Warm Fronts

    Science.gov (United States)

    Naud, Catherine M.; Posselt, Derek J.; van den Heever, Susan C.

    2012-01-01

    Extratropical cyclones are responsible for most of the precipitation and wind damage in the midlatitudes during the cold season, but there are still uncertainties on how they will change in a warming climate. An ubiquitous problem amongst General Circulation Models (GCMs) is a lack of cloudiness over the southern oceans that may be in part caused by a lack of clouds in cyclones. We analyze CloudSat, CALIPSO and AMSR-E observations for 3 austral and boreal cold seasons and composite cloud frequency of occurrence and precipitation at the warm fronts for northern and southern hemisphere oceanic cyclones. We find that cloud frequency of occurrence and precipitation rate are similar in the early stage of the cyclone life cycle in both northern and southern hemispheres. As cyclones evolve and reach their mature stage, cloudiness and precipitation at the warm front increase in the northern hemisphere but decrease in the southern hemisphere. This is partly caused by lower amounts of precipitable water being available to southern hemisphere cyclones, and smaller increases in wind speed as the cyclones evolve. Southern hemisphere cloud occurrence at the warm front is found to be more sensitive to the amount of moisture in the warm sector than to wind speeds. This suggests that cloudiness in southern hemisphere storms may be more susceptible to changes in atmospheric water vapor content, and thus to changes in surface temperature than their northern hemisphere counterparts. These differences between northern and southern hemisphere cyclones are statistically robust, indicating A-Train-based analyses as useful tools for evaluation of GCMs in the next IPCC report.

  10. Relation between tropical cyclone heat potential and cyclone intensity in the North Indian Ocean

    Science.gov (United States)

    Jangir, B.; Swain, D.; Udaya Bhaskar, T. V. S.

    2016-05-01

    Ocean Heat Content (OHC) plays a significant role in modulating the intensity of Tropical Cyclones (TC) in terms of the oceanic energy available to TCs. TC Heat Potential (TCHP), an estimate of OHC, is thus known to be a useful indicator of TC genesis and intensification. In the present study, we analyze the role of TCHP in intensification of TCs in the North Indian Ocean (NIO) through statistical comparisons between TCHP and Cyclone Intensities (CI). A total of 27 TCs (20 in the Bay of Bengal, and 7 in the Arabian Sea) during the period 2005-2012 have been analyzed using TCHP data from Global Ocean Data Assimilation System (GODAS) model of Indian National Center for Ocean Information Services and cyclone best track data from India Meteorological Department. Out of the 27 cyclones analyzed, 58% (86%) in the Bay (Arabian Sea) have negative correlation and 42% (14%) cyclones have positive correlation between CI and TCHP. On the whole, more than 60% cyclones in the NIO show negative correlations between CI and TCHP. The negative percentage further increases for TCHP leading CI by 24 and 48 hours. Similar trend is also seen with satellite derived TCHP data obtained from National Remote Sensing Center and TC best track data from Joint Typhoon Warming Centre. Hence, it is postulated that TCHP alone need not be the only significant oceanographic parameter, apart from sea surface temperature, responsible for intensification and propagation of TCs in the NIO.

  11. Tropical Cyclone Report, 1987.

    Science.gov (United States)

    1987-01-01

    NAVOCEANCOMDET ALAMEDA CIUDAD UNIVERSITARIA , MEXICO NAVOCEANCOMDET ASHEVILLE CIVIL DEFENSE, SAIPAN NAVOCEANCOMDET ATSUGI CINCPACFLT NAVOCEANCOMDET BARBERS...minute mean) in "" begin to rotate about one another. When intense tropical the range of 34 to 63 kt (17 to 32 m/sec) inclusive . * -’.- cyclones are

  12. Tropical Cyclone Report, 1990.

    Science.gov (United States)

    1990-01-01

    surface winds in the range of 34 to center of a tropical cyclone. 63 kt (17 to 32 m/sec) inclusive . MAXIMUA SUSTAINED WIND - The highest TROPICAL UPPER...PASADENA CIUDAD UNIVERSITARIA . MEXICO LISD CAMP SPRINGS CENTER, MD CIVIL DEFENSE, BELAU LOS ANGELES PUBLIC LIBRARY CIVIL DEFENSE, MAJURO MAURITIUS

  13. Impacts of tropical cyclones on Fiji and Samoa

    Science.gov (United States)

    Kuleshov, Yuriy; Prakash, Bipendra; Atalifo, Terry; Waqaicelua, Alipate; Seuseu, Sunny; Ausetalia Titimaea, Mulipola

    2013-04-01

    on Samoa totalled to US130 million. Cyclone Val caused damage and destruction to 95% of houses in Samoa and severe crop damage; total damage was estimated as US200 million. Recently, severe tropical cyclone Evan affected Samoa and Fiji (December 2012). Significant progress in operational tropical cyclone forecasting has been achieved over the past few decades which resulted in improving early warning system but death toll attributed to cyclones is still high - at least 14 deaths in Samoa are related to cyclone Evan (luckily, no death reports in Fiji). Cyclone-related economic losses also remain very high making significant negative impact on economies of the countries. Preliminary assessment of damage caused by cyclone Evan in Fiji indicates loses of about 75.29 million. By the end of this century projections suggest decreasing numbers of tropical cyclones but a possible shift towards more intense categories. In addition, geographic shifts in distribution of tropical cyclone occurrences caused by warming of the atmospheric and oceanic environment are possible. This should be taken in consideration by authorities of the Pacific Island Countries when developing adaptation strategies to increasing tropical cyclone risk due to climate change.

  14. Assessing Tropical Cyclone Damage

    Science.gov (United States)

    Done, J.; Czajkowski, J.

    2012-12-01

    Landfalling tropical cyclones impact large coastal and inland areas causing direct damage due to winds, storm-surge flooding, tornadoes, and precipitation; as well as causing substantial indirect damage such as electrical outages and business interruption. The likely climate change impact of increased tropical cyclone intensity, combined with increases in exposure, bring the possibility of increased damage in the future. A considerable amount of research has focused on modeling economic damage due to tropical cyclones, and a series of indices have been developed to assess damages under climate change. We highlight a number of ways this research can be improved through a series of case study analyses. First, historical loss estimates are revisited to properly account for; time, impacted regions, the source of damage by type, and whether the damage was direct/indirect and insured/uninsured. Second, the drivers of loss from both the socio-economic and physical side are examined. A case is made to move beyond the use of maximum wind speed to more stable metrics and the use of other characteristics of the wind field such as direction, degree of gustiness, and duration is explored. A novel approach presented here is the potential to model losses directly as a function of climate variables such as sea surface temperature, greenhouse gases, and aerosols. This work is the first stage in the development of a tropical cyclone loss model to enable projections of losses under scenarios of both socio-economic change (such as population migration or altered policy) and physical change (such as shifts in tropical cyclone activity one from basin to another or within the same basin).

  15. Tropical Cyclones within the Sedimentary Record: Analyzing Overwash Deposition from Event to Millennial Timescales

    Science.gov (United States)

    2009-02-01

    grain-size diameter for siliciclastic particles using the relationship developed by Ferguson and Church (2004). Predictions using this relationship...of intense hurricane strikes from New Jersey: Geology, v. 29, p. 615–618, doi: 10.1130/0091–7613(2001)029򒨧:SEOIHS>2.0.CO;2. Ferguson , R.I., and...Stone, G. W., Liu, B., Pepper , D. A., and Wang, P. (2004). The importance of extratropical and tropical cyclones on the short-term evolution of

  16. Butterflies, Black swans and Dragon kings: How to use the Dynamical Systems Theory to build a "zoology" of mid-latitude circulation atmospheric extremes?

    Science.gov (United States)

    Faranda, D.; Yiou, P.; Alvarez-Castro, M. C. M.

    2015-12-01

    A combination of dynamical systems and statistical techniques allows for a robust assessment of the dynamical properties of the mid-latitude atmospheric circulation. Extremes at different spatial and time scales are not only associated to exceptionally intense weather structures (e.g. extra-tropical cyclones) but also to rapid changes of circulation regimes (thunderstorms, supercells) or the extreme persistence of weather structure (heat waves, cold spells). We will show how the dynamical systems theory of recurrence combined to the extreme value theory can take into account the spatial and temporal dependence structure of the mid-latitude circulation structures and provide information on the statistics of extreme events.

  17. A Look Under the Hood: How the JPL Tropical Cyclone Information System Uses Database Technologies to Present Big Data to Users

    Science.gov (United States)

    Knosp, B.; Gangl, M.; Hristova-Veleva, S. M.; Kim, R. M.; Li, P.; Turk, J.; Vu, Q. A.

    2015-12-01

    The JPL Tropical Cyclone Information System (TCIS) brings together satellite, aircraft, and model forecast data from several NASA, NOAA, and other data centers to assist researchers in comparing and analyzing data and model forecast related to tropical cyclones. The TCIS has been running a near-real time (NRT) data portal during North Atlantic hurricane season that typically runs from June through October each year, since 2010. Data collected by the TCIS varies by type, format, contents, and frequency and is served to the user in two ways: (1) as image overlays on a virtual globe and (2) as derived output from a suite of analysis tools. In order to support these two functions, the data must be collected and then made searchable by criteria such as date, mission, product, pressure level, and geospatial region. Creating a database architecture that is flexible enough to manage, intelligently interrogate, and ultimately present this disparate data to the user in a meaningful way has been the primary challenge. The database solution for the TCIS has been to use a hybrid MySQL + Solr implementation. After testing other relational database and NoSQL solutions, such as PostgreSQL and MongoDB respectively, this solution has given the TCIS the best offerings in terms of query speed and result reliability. This database solution also supports the challenging (and memory overwhelming) geospatial queries that are necessary to support analysis tools requested by users. Though hardly new technologies on their own, our implementation of MySQL + Solr had to be customized and tuned to be able to accurately store, index, and search the TCIS data holdings. In this presentation, we will discuss how we arrived on our MySQL + Solr database architecture, why it offers us the most consistent fast and reliable results, and how it supports our front end so that we can offer users a look into our "big data" holdings.

  18. Mesoscale Processes in Tropical Cyclones

    Science.gov (United States)

    2016-06-07

    analysis of the manner in which atmospheric vortices can interact; the first research results on the presence of mesoscale vortices in tropical cyclones...Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be...tropical cyclone motion; thermodynamic estimation of tropical cyclone intensity, which has been utilized in a WMO statement on climate change and tropical

  19. Characteristics of tropical cyclones and overshooting from GPS radio occultation data

    Science.gov (United States)

    Biondi, Riccardo; Rieckh, Therese; Steiner, Andrea; Kirchengast, Gottfried

    2014-05-01

    Tropical cyclones (TCs) are extreme weather events causing every year huge damages and several deaths. In some countries they are the natural catastrophes accounting for the major economic damages. The thermal structure of TCs gives important information on the cloud top height allowing for a better understanding of the troposphere-stratosphere transport, which is still poorly understood. The measurement of atmospheric parameters (such as temperature, pressure and humidity) with high vertical resolution and accuracy in the upper troposphere and lower stratosphere (UTLS) is difficult especially during severe weather events (e.g TCs). Satellite remote sensing has improved the TC forecast and monitoring accuracy. In the last decade the Global Positioning Systems (GPS) Radio Occultation (RO) technique contributed to improve our knowledge especially at high troposphere altitudes and in remote regions of the globe thanks to the high vertical resolution, avoiding temperature smoothing issues (given by microwave and infrared instruments) in the UTLS and improving the poor temporal resolution and global coverage given by lidars and radars. We selected more than twenty-thousand GPS RO profiles co-located with TC best tracks for the period 2001 to 2012 and computed temperature anomaly profiles relative to a RO background climatology in order to detect TC cloud tops. We characterized the thermal structure for different ocean basins and for different TC intensities, distinguishing between tropical and extra-tropical cases. The analysis shows that all investigated storms have a common feature: they warm the troposphere and cool the UTLS near the cloud top. This behavior is amplified in the extra-tropical areas. Results reveal that the storms' cloud tops in the southern hemisphere basins reach higher altitudes and lower temperatures than in the northern hemisphere basins. We furthermore compared the cloud top height of each profile with the mean tropopause altitude (from the RO

  20. The Research On The Performance Of Oil-gas Cyclone Separators In Oil Injected Compressor Systems With Considering The Collision And Breakup Of Oil Droplets

    OpenAIRE

    2012-01-01

    The high-speed swirling flow field in the cyclone oil-gas separator will cause the breakup of oil droplets, thus reducing the separation efficiency. In this paper, the performance of an oil-gas cyclone separator was investigated through both numerical simulations and experiments with considering the breakup of oil droplets in oil-gas cyclone separators. The gas flow field was simulated using the RSM turbulence model and the trajectory of the oil droplets was calculated by the Discrete Phase M...

  1. Development of a cyclone separator with new design

    Energy Technology Data Exchange (ETDEWEB)

    Molerus, O. [Lehrstuhl fuer Mechanische Verfahrenstechnik, Univ. Erlangen-Nuernberg, Erlangen (Germany); Glueckler, M. [Lehrstuhl fuer Mechanische Verfahrenstechnik, Univ. Erlangen-Nuernberg, Erlangen (Germany)

    1996-01-01

    A new cyclone separator is proposed which is designed for the gentle separation of particles from a gas phase (with respect to breakage and attrition of the particles) for usual solid loadings (1<{mu}<15) and which is suitable for downer systems. In order to evaluate the quality of performance, test experiments were carried out that gave overall collection efficiencies of up to 99.9% and cut sizes in the range of 10{mu}m. Regarding particle breakage and attrition, the new cyclone showed significantly less particle comminution than a comparable conventional cyclone. (orig.)

  2. Improved Satellite Techniques for Monitoring and Forecasting the Transition of Hurricanes to Extratropical Storms

    Science.gov (United States)

    Folmer, Michael; Halverson, Jeffrey; Berndt, Emily; Dunion, Jason; Goodman, Steve; Goldberg, Mitch

    2014-01-01

    The Geostationary Operational Environmental Satellites R-Series (GOES-R) and Joint Polar Satellite System (JPSS) Satellite Proving Grounds have introduced multiple proxy and operational products into operations over the last few years. Some of these products have proven to be useful in current operations at various National Weather Service (NWS) offices and national centers as a first look at future satellite capabilities. Forecasters at the National Hurricane Center (NHC), Ocean Prediction Center (OPC), NESDIS Satellite Analysis Branch (SAB) and the NASA Hurricane and Severe Storms Sentinel (HS3) field campaign have had access to a few of these products to assist in monitoring extratropical transitions of hurricanes. The red, green, blue (RGB) Air Mass product provides forecasters with an enhanced view of various air masses in one complete image to help differentiate between possible stratospheric/tropospheric interactions, moist tropical air masses, and cool, continental/maritime air masses. As a compliment to this product, a new Atmospheric Infrared Sounder (AIRS) and Cross-track Infrared Sounder (CrIS) Ozone product was introduced in the past year to assist in diagnosing the dry air intrusions seen in the RGB Air Mass product. Finally, a lightning density product was introduced to forecasters as a precursor to the new Geostationary Lightning Mapper (GLM) that will be housed on GOES-R, to monitor the most active regions of convection, which might indicate a disruption in the tropical environment and even signal the onset of extratropical transition. This presentation will focus on a few case studies that exhibit extratropical transition and point out the usefulness of these new satellite techniques in aiding forecasters forecast these challenging events.

  3. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    OpenAIRE

    2006-01-01

    Ozone and carbone monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a lagrangian-based study (backward trajectories and a Reverse Domain Filling technique) to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in th...

  4. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2006-01-01

    Full Text Available Ozone and carbon monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a Lagrangian-based study (backward trajectories and a Reverse Domain Filling technique to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in the lower troposphere (O3≃100 ppbv; CO≃90 ppbv in the dry airstream of the cyclone, and again in the upper troposphere (O3≃200 ppbv; CO≃90 ppbv on the northern side of the large scale potential vorticity feature associated with baroclinic development. In agreement with the maritime development of the cyclone, the chemical composition of the anticyclonic portion of the warm conveyor belt outflow (O3≃40 ppbv; CO≃85 ppbv corresponds to the lowest mixing ratios of both ozone and carbon monoxide in the upper tropospheric airborne observations. The uncertain degree of confidence of the Lagrangian-based technique applied to a 100 km segment of upper level airborne observations with high ozone (200 ppbv and relatively low CO (80 ppbv observed northwest of the cyclone prevents identification of the ozone enrichment process of air parcels embedded in the cyclonic part of the upper level outflow of the warm conveyor belt. Different hypotheses of stratosphere-troposphere exchange are discussed.

  5. Stratosphere-troposphere exchange in a summertime extratropical low: analysis

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2005-11-01

    Full Text Available Ozone and carbone monoxide measurements sampled during two commercial flights in airstreams of a summertime midlatitude cyclone are analysed with a lagrangian-based study (backward trajectories and a Reverse Domain Filling technique to gain a comprehensive understanding of transport effects on trace gas distributions. The study demonstrates that summertime cyclones can be associated with deep stratosphere-troposphere transport. A tropopause fold is sampled twice in its life cycle, once in the lower troposphere (O3≃100 ppbv; CO≃90 ppbv in the dry airstream of the cyclone, and again in the upper troposphere (O3≃200 ppbv; CO≃90 ppbv on the northern side of the large scale potential vorticity feature associated with baroclinic development. In agreement to the maritime development of the cyclone, the chemical composition of the anticyclonic part outflow of the warm conveyor belt (O3≃40 ppbv; CO≃85 ppbv corresponds to the lowest mixing ratios of both ozone and carbone monoxide in upper tropospheric airborne observations. The uncertain degree of confidence of the Lagrangian-based technique applied to a 100 km segment of upper level airborne observations with high ozone (200 ppbv and relatively low CO (80 ppbv observed northwest of the cyclone prevents to identify the ozone enrichment process of air parcels embedded in the cyclonic part of the upper level outflow of the warm conveyor belt. Different hypotheses of stratosphere-troposphere exchange are discussed.

  6. Conceptual Models of Frontal Cyclones.

    Science.gov (United States)

    Eagleman, Joe R.

    1981-01-01

    This discussion of weather models uses maps to illustrate the differences among three types of frontal cyclones (long wave, short wave, and troughs). Awareness of these cyclones can provide clues to atmospheric conditions which can lead toward accurate weather forecasting. (AM)

  7. Tropical Cyclone Report

    Science.gov (United States)

    1989-01-01

    GUARD 160 (13-14W)TS KEN-LOLA BOUCHARD 86 (32W) TY GAY CRITTENDEN 166 (15W) TY MAC BOUCHARD 92 (33W) TY HUNT SHOEMAKER 172 (16W) TY OWEN CRITTENDEN 98...GURAL 188 TC 02A BOUCHARD 190 TC 32W ( GAY ) CRI’TTENDEN 166 4. SUMMARY OF SOUTH PACIFIC AND SOUTH INDIAN OCEAN TROPICAL CYCLONES ............. 193 4.1...Commander Naval ICAO International Civil Aviation AFB Air Force Base Oceanography Command Organization AFGWC Air Force Global Weather COSM or INIT Initial

  8. Southern annular mode: tropical-extratropical interactions and impacts

    CSIR Research Space (South Africa)

    Fauchereau, N

    2009-09-01

    Full Text Available ?Dept.,?University?of?Cape?Town,?South?Africa 1.?Introduction The?Southern?Annular?Mode?(SAM,?also?called?Antarctic? Oscillation)?is?the?dominant?mode?of?extratropical?(south? of ? 20S) ? low?frequency ? atmospheric ? variability ? ? in ? the? Southern?Hemisphere.?It ?basically...?with?a?seasonally?adjusted?principal?component? index,?17th?Climate?diagnostics?workshop,?Norman,?OK,? 52?57. ...

  9. IMPACT ASSESSMENT OF TROPICAL CYCLONE HUD HUD ON COASTAL REGION OF VISAKHAPATNAM, ANDHRA PRADESH, INDIA

    Directory of Open Access Journals (Sweden)

    G. Vivek

    2015-10-01

    Full Text Available Tropical cyclone is a rapidly rotating storm system characterized by a low pressure center, strong winds, and a spiral arrangements of thunderstorms that produce heavy rain. Tropical cyclones typically form over large bodies of relatively warm water. On 6th October 2014 Hud Hud originates from a low pressure system that formed under the influence of an upper air cyclonic circulation in the Andaman Sea. On 9th October 2014 the IMD department classified the Hud Hud as a very severe cyclonic storm on IMD scale and category 4 on Staffir-Simpson scale. The cyclone hit the coast of Visakhapatnam on 12th October 2014 at wind speed of 175 km/h which caused extensive damage to the city and the neighbouring districts. The damage caused by Cyclone Hud Hud not only changed the landscape of the port city, but also made it the first city in the country to be directly hit by a cyclone since 1891 as per the records of the IMD. The remote sensing technique used here is NDVI. NDVI will separate vegetation and non-vegetation part. The NDVI will be classified in ERDAS and calculated the area using ARCGIS. The satellite data of 4th October 2014 show s before the cyclone, 14th October 2014 shows after the cyclone and 7th December 2014 after two month of cyclone.

  10. Up-date on cyclone combustion and cyclone boilers

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Felipe Alfaia do; Nogueira, Manoel Fernandes Martins; Rocha, Rodrigo Carnera Castro da; Gazel, Hussein Felix; Martins, Diego Henrique dos Reis [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Campus Universitario Jose da Silveira Netto], E-mails: mfmn@ufpa.br, mfmn@ufpa.br

    2010-07-01

    The boiler concept has been around for more than 70 years, and there are many types available. Boilers provide steam or hot water for industrial and commercial use. The Federal University of Para (UFPA) through the research group EBMA (Energy,Biomass and Environment) has been developing cyclonic furnace with a water wall, a boiler, aiming to use regional timbers (sawdust) and agro-industries residues as fuel to produce steam to be used in industrial processes as well as in power generation,. The use of cyclonic combustion for burning waste instead of burning in a fixed bed is mainly due to two factors efficiency improvement causing a more compact boiler and less risk of explosion, since their process does not generate an accumulation of volatile. Present state-of-art for commercial cyclone boilers has as set up a cyclone combustor with two combustion chambers, in fluid communication, where there ducts for supplying air and fuel directly into the first chamber and for forming a cyclonic flow pattern and a heat exchanger surrounding the second chamber for keeping low combustion temperature in both chambers. This paper shows the results of a literature review about design, construction and operation of cyclonic boilers using solid, liquid or gaseous fuel. This information has been used for the design of a cyclone boiler to be constructed at UFPA for research purposes and its basic concept is presented at the end of this article. (author)

  11. Objective Tracking of Tropical Cyclones in the North-West Pacific Basin Based on Wind Field Information only

    Science.gov (United States)

    Leckebusch, G. C.; Befort, D. J.; Kruschke, T.

    2016-12-01

    Although only ca. 12% of the global insured losses of natural disasters occurred in Asia, there are two major reasons to be concerned about risks in Asia: a) The fraction of loss events was substantial higher with 39% of which 94% were due to atmospheric processes; b) Asia and especially China, is undergoing quick transitions and especially the insurance market is rapidly growing. In order to allow for the estimation of potential future (loss) impacts in East-Asia, in this study we further developed and applied a feature tracking system based on extreme wind speed occurrences to tropical cyclones, which was originally developed for extra-tropical cyclones (Leckebusch et al., 2008). In principle, wind fields will be identified and tracked once a coherent exceedance of local percentile thresholds is identified. The focus on severe wind impact will allow an objective link between the strength of a cyclone and its potential damages over land. The wind tracking is developed in such a way to be applicable also to course-gridded AOGCM simulation. In the presented configuration the wind tracking algorithm is applied to the Japanese reanalysis (JRA55) and TC Identification is based on 850hPa wind speeds (6h resolution) from 1979 to 2014 over the Western North Pacific region. For validation the IBTrACS Best Track archive version v03r8 is used. Out of all 904 observed tracks, about 62% can be matched to at least one windstorm event identified in JRA55. It is found that the relative amount of matched best tracks increases with the maximum intensity. Thus, a positive matching (hit rate) of above 98% for Violent Typhoons (VTY), above 90% for Very Strong Typhoons (VSTY), about 75% for Typhoons (TY), and still some 50% for less intense TCs (TD, TS, STS) is found. This result is extremely encouraging to apply this technique to AOGCM outputs and to derive information about affected regions and intensity-frequency distributions potentially changed under future climate conditions.

  12. Characteristics of the internal and external sources of the Mediterranean synoptic cyclones for the period 1956-2013

    Science.gov (United States)

    Almazroui, Mansour; Awad, Adel M.; Nazrul Islam, M.

    2017-07-01

    This paper investigates the main sources and features of the Mediterranean synoptic cyclones affecting the basin, using the cyclone tracks. The cyclones' tracks are identified using sea level pressure (SLP) from the NCEP/NCAR reanalysis data for the period 1956-2013. The identified cyclones are classified into two categories: basin affected and basin non-affected. Most of the basin-affected (non-affected) cyclones are internal (external), i.e., generated inside (outside) the Mediterranean basin. This study reveals four (five) main sources of internal (external) cyclones. These four (five) main sources generated about 63.76% (57.25%) of the internal (external) cyclones. Seasonal analysis shows that most of the basin-affected internal (external) cyclones were generated in the winter (spring) season. The lowest number of cyclones were found in the summer. Moreover, the synoptic study of the atmospheric systems accompanied the highest- and lowest-generated years demonstrates that the deepening of the north Europe cyclones and the relative positions of Azores- and Siberian-high systems represent the important factors that influence the number of internal cyclones. Essential factors influencing the external cyclones are the strength of the maximum upper wind, Azores high, Siberian high, and orientations of their ridges.

  13. Growth of cyclone Viyaru and Phailin – a comparative study

    Indian Academy of Sciences (India)

    S D Kotal; S K Bhattacharya; S K Roy Bhowmik; P K Kundu

    2014-10-01

    The tropical cyclone Viyaru maintained a unique quasi-uniform intensity during its life span. Despite being in contact with sea surface for < 120 hr travelling about 2150 km, the cyclonic storm (CS) intensity, once attained, did not intensify further, hitherto not exhibited by any other system over the Bay of Bengal. On the contrary, the cyclone Phailin over the Bay of Bengal intensified into very severe cyclonic storm (VSCS) within about 48 hr from its formation as depression. The system also experienced rapid intensification phase (intensity increased by 30 kts or more during subsequent 24 hours) during its life time and maximum intensity reached up to 115 kts. In this paper, a comparative study is carried out to explore the evolution of the various thermodynamical parameters and possible reasons for such converse features of the two cyclones. Analysis of thermodynamical parameters shows that the development of the lower tropospheric and upper tropospheric potential vorticity (PV) was low and quasi-static during the lifecycle of the cyclone Viyaru. For the cyclone Phailin, there was continuous development of the lower tropospheric and upper tropospheric PV, which attained a very high value during its lifecycle. Also there was poor and fluctuating diabatic heating in the middle and upper troposphere and cooling in the lower troposphere for Viyaru. On the contrary, the diabatic heating was positive from lower to upper troposphere with continuous development and increase up to 6°C in the upper troposphere. The analyses of cross sections of diabatic heating, PV, and the 1000–500 hPa geopotential metre (gpm) thickness contours indicate that the cyclone Viyaru was vertically tilted (westward) and lacked axisymmetry in its structure and converse features (axisymmetric and vertical) that occurred for the cyclone Phailin. In addition, there was a penetration of dry air in the middle troposphere of Viyaru, whereas high moisture existed in the middle troposphere of

  14. The role of latent heat in kinetic energy conversions of South Pacific cyclones

    Science.gov (United States)

    Kann, Deirdre M.; Vincent, Dayton G.

    1986-01-01

    The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.

  15. The role of latent heat in kinetic energy conversions of South Pacific cyclones

    Science.gov (United States)

    Kann, Deirdre M.; Vincent, Dayton G.

    1986-01-01

    The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.

  16. Scavenging of biomass burning refractory black carbon and ice nuclei in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-01-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the Western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Cloud hydrometeors were evaporated by a counterflow virtual impactor and the residue was sampled by a single particle soot photometer (SP2 instrument and a continuous flow diffusion chamber ice nucleus detector. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. In storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN measurements from ice particle residues generally agreed well with simultaneous measurements of total ice concentrations provided that the measurements were made at ambient temperatures similar to those in the CFDC chamber, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures (−22 to −6.4 °C, ice particle concentrations were similar to IN concentrations at CFDC chamber temperatures representative of colder temperatures. This is consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by sedimentation to lower altitudes. Homogeneous freezing did not appear to contribute significantly to midlevel ice concentrations and rime-splintering was also unlikely due to the absence of significant supercooled liquid water in the warm sector clouds. IN number concentrations were typically about a~factor of five to ten lower than simultaneous measurements of rBC concentrations in cloud.

  17. Understanding the varied response of the extratropical storm tracks to climate change.

    Science.gov (United States)

    O'Gorman, Paul A

    2010-11-09

    Transient eddies in the extratropical storm tracks are a primary mechanism for the transport of momentum, energy, and water in the atmosphere, and as such are a major component of the climate system. Changes in the extratropical storm tracks under global warming would impact these transports, the ocean circulation and carbon cycle, and society through changing weather patterns. I show that the southern storm track intensifies in the multimodel mean of simulations of 21st century climate change, and that the seasonal cycle of storm-track intensity increases in amplitude in both hemispheres. I use observations of the present-day seasonal cycle to confirm the relationship between storm-track intensity and the mean available potential energy of the atmosphere, and show how this quantitative relationship can be used to account for much of the varied response in storm-track intensity to global warming, including substantially different responses in simulations with different climate models. The results suggest that storm-track intensity is not related in a simple way to global-mean surface temperature, so that, for example, a stronger southern storm track in response to present-day global warming does not imply it was also stronger in hothouse climates of the past.

  18. 65-nm Cyclone Ⅲ FPGA

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Altera公司低功耗、低成本Cyclone Ⅲ系列65nm FPGA所有8个型号的产品级芯片实现量产,Cyclone Ⅲ系列产品已迅速应用于无线、军事、显示、汽车和工业市场的大量客户系统中。

  19. Extratropical North Atlantic SST influence on Sahel rainfall

    Science.gov (United States)

    Liu, Y.; Chiang, J. C.

    2013-12-01

    We present evidence suggesting that the late 1960's Sahel drought was linked to an abrupt cooling in the extratropical North Atlantic, whose influence was then propagated to the Sahel by atmospheric teleconnection. Such linkages have been observed in paleoclimate during abrupt climate changes of the last glacial period. They have also occurred in coupled model simulations of Atlantic meridional overturning circulation (AMOC) slowdown, the latter being the leading cause of said paleoclimate abrupt changes. The AMOC-slowdown simulations show a characteristic global pattern of climate changes, including a northern hemispheric-wide cooling and increased surface pressure, and weakening of the West African and Asian monsoons. We show that an observed northern-hemispheric pattern of changes, resembling the AMOC slowdown, occurred during the late 1960's, co-incident with the Sahel drought. A combined principal component analysis of 20th century surface temperature, sea level pressure and precipitation extracts a leading mode whose spatial pattern closely resemble the impacts of AMOC slowdown. A similar analysis of AMIP-type simulations forced by 20th century observed forcings shows a similar result, suggesting that the origins of the climate change reside in SST changes, in particular over extratropical North Atlantic. Taken together, the results suggests the influence of extratropical North Atlantic cooling on the 20th century Sahel drought, and a teleconnection pathway through surface/tropospheric cooling. Motivated by our observational result, we investigated atmospheric teleconnection mechanisms of extratropical North Atlantic cooling in an atmospheric general circulation model (GCM) coupled with slab ocean. Our results indicate the central role of tropospheric cooling in communicating the influence on the Sahel. We explicitly show this using regional climate model simulation of the Sahel, with air temperature and associated humidity anomalies from the GCM simulation

  20. Emergency Department Presentations following Tropical Cyclone Yasi.

    Directory of Open Access Journals (Sweden)

    Peter Aitken

    Full Text Available Emergency departments see an increase in cases during cyclones. The aim of this study is to describe patient presentations to the Emergency Department (ED of a tertiary level hospital (Townsville following a tropical cyclone (Yasi. Specific areas of focus include changes in: patient demographics (age and gender, triage categories, and classification of diseases.Data were extracted from the Townsville Hospitals ED information system (EDIS for three periods in 2009, 2010 and 2011 to coincide with formation of Cyclone Yasi (31 January 2011 to six days after Yasi crossed the coast line (8 February 2012. The analysis explored the changes in ICD10-AM 4-character classification and presented at the Chapter level.There was a marked increase in the number of patients attending the ED during Yasi, particularly those aged over 65 years with a maximum daily attendance of 372 patients on 4 Feb 2011. The most marked increases were in: Triage categories--4 and 5; and ICD categories--diseases of the skin and subcutaneous tissue (L00-L99, and factors influencing health care status (Z00-Z99. The most common diagnostic presentation across all years was injury (S00-T98.There was an increase in presentations to the ED of TTH, which peaked in the first 24-48 hours following the cyclone and returned to normal over a five-day period. The changes in presentations were mostly an amplification of normal attendance patterns with some altered areas of activity. Injury patterns are similar to overseas experience.

  1. Black Swan Tropical Cyclones

    Science.gov (United States)

    Emanuel, K.; Lin, N.

    2012-12-01

    Virtually all assessments of tropical cyclone risk are based on historical records, which are limited to a few hundred years at most. Yet stronger TCs may occur in the future and at places that have not been affected historically. Such events lie outside the realm of historically based expectations and may have extreme impacts. Their occurrences are also often made explainable after the fact (e.g., Hurricane Katrina). We nickname such potential future TCs, characterized by rarity, extreme impact, and retrospective predictability, "black swans" (Nassim Nicholas Taleb, 2007). As, by definition, black swan TCs have yet to happen, statistical methods that solely rely on historical track data cannot predict their occurrence. Global climate models lack the capability to predict intense storms, even with a resolution as high as 14 km (Emanuel et al. 2010). Also, most dynamic downscaling methods (e.g., Bender et al. 2010) are still limited in horizontal resolution and are too expensive to implement to generate enough events to include rare ones. In this study, we apply a simpler statistical/deterministic hurricane model (Emanuel et al. 2006) to simulate large numbers of synthetic storms under a given (observed or projected) climate condition. The method has been shown to generate realistic extremes in various basins (Emanuel et al. 2008 and 2010). We also apply a hydrodynamic model (ADCIRC; Luettich et al. 1992) to simulate the storm surges generated by these storms. We then search for black swan TCs, in terms of the joint wind and surge damage potential, in the generated large databases. Heavy rainfall is another important TC hazard and will be considered in a future study. We focus on three areas: Tampa Bay in the U.S., the Persian Gulf, and Darwin in Australia. Tampa Bay is highly vulnerable to storm surge as it is surrounded by shallow water and low-lying lands, much of which may be inundated by a storm tide of 6 m. High surges are generated by storms with a broad

  2. Baroclinic mixing of potential vorticity as the principal sharpening mechanism for the extratropical Tropopause Inversion Layer

    Science.gov (United States)

    Wang, Shu Meir; Geller, Marvin A.

    2016-09-01

    Previous works have shown that a dry, idealized general circulation model could produce many features of the extratropical Tropopause Inversion Layer (TIL). In particular, the following have been shown, but no explanations were given for these results. (1) A sharper extratropical TIL resulted more from increased horizontal resolution than from increased vertical resolution. (2) If the Equator-to-Pole temperature gradient was varied, the annual variation of the extratropical TIL found in observations could be reproduced. (3) The extratropical TIL altitude showed excellent correlation with the upper tropospheric relative vorticity, as had been previously proposed. (4) Increased horizontal model resolutions led to extratropical TILs that were at lower altitudes. We show that these conclusions follow from baroclinic mixing of high stratospheric potential vorticity into the troposphere being the principal sharpening mechanism for the extratropical TIL and the increased baroclinic activity occurring in higher horizontal resolution models. We furthermore suggest that the distance from the jet exerts a greater influence on the height and sharpness of the extratropical TIL than does the upper tropospheric relative vorticity, and this accounts for the annual behavior of the extratropical TIL found in observations and reproduced with a dry, mechanistic, global model.

  3. Analysis of the efficiency of a cloth cyclone: the effect of the permeability of the filtering medium

    Directory of Open Access Journals (Sweden)

    M.V. Rodrigues

    2003-10-01

    Full Text Available The cloth cyclone is a solid-gas separation device that consists of a Lapple cyclone whose conical section has been replaced by a conical filtering wall. The present research was undertaken with the aim of examining the influence of a conical filtering section made of three different materials on the performance of a Lapple design cyclone. The overall efficiency and pressure drops of the cloth cyclone and a conventional one were compared. The effect of the filtering medium on the behavior of the cyclone was also evaluated using an equation that correlates the cut size diameter with the operational conditions, the properties of the gas-solid system and the resistance of the filtering medium. The experimental results demonstrated that the overall efficiency of the conventional cyclone was similar to that of the proposed device, with the latter displaying a reduction in pressure drop. Consequently, energy costs are lowered when cloth cyclones are used.

  4. The NASA Cyclone Global Navigation Satellite System (CYGNSS): A Constellation of Bi-static Ocean Scatterometer Microsatellites to Probe the Inner Core of Hurricanes

    Science.gov (United States)

    Ruf, C. S.; Clarizia, M. P.; Ridley, A. J.; Gleason, S.; O'Brien, A.

    2014-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) is the first NASA Earth Ventures spaceborne mission. CYGNSS consists of a constellation of eight small observatories carried into orbit on a single launch vehicle. The eight satellites comprise a constellation that flies closely together to measure the ocean surface wind field with unprecedented temporal resolution and spatial coverage, under all precipitating conditions, and over the full dynamic range of wind speeds experienced in a TC. The 8 CYGNSS observatories will fly in 500 km circular orbits at a common inclination of ~35°. Each observatory includes a Delay Doppler Mapping Instrument (DDMI) consisting of a modified GPS receiver capable of measuring surface scattering, a low gain zenith antenna for measurement of the direct GPS signal, and two high gain nadir antennas for measurement of the weaker scattered signal. Each DDMI is capable of measuring 4 simultaneous bi-static reflections, resulting in a total of 32 wind measurements per second across the globe by the full constellation. Simulation studies will be presented which examine the sampling as functions of various orbit parameters of the constellation. For comparison purposes, a similar analysis is conducted using the sampling of several past and present conventional spaceborne ocean wind scatterometers. Differences in the ability of the sensors to resolve the evolution of the TC inner core will be examined. The CYGNSS observatories are currently in Phase C development. An update on the current status of the mission will be presented, including the expected precision, accuracy and spatial and temporal sampling properties of the retrieved winds.

  5. Observational Diagnoses of Extratropical Ozone STE During the Aura Era

    Science.gov (United States)

    Olsen, Mark A.; Douglass, Anne R.; Witte, Jacquie C.; Kaplan, Trevor B.

    2011-01-01

    The transport of ozone from the stratosphere to the extratropical troposphere is an important boundary condition to tropospheric chemistry. However, previous direct estimates from models and indirect estimates from observations have poorly constrained the magnitude of ozone stratosphere-troposphere exchange (STE). In this study we provide a direct diagnosis of the extratropical ozone STE using data from the Microwave Limb Sounder on Aura and output of the MERRA reanalysis over the time period from 2005 to the present. We find that the mean annual STE is about 275 Tg/yr and 205 Tg/yr in the NH and SH, respectively. The interannual variability of the magnitude is about twice as great in the NH than the SH. We find that this variability is dominated by the seasonal variability during the late winter and spring. A comparison of the ozone flux to the mass flux reveals that there is not a simple relationship between the two quantities. This presentation will also examine the magnitude and distribution of ozone in the lower stratosphere relative to the years of maximum and minimum ozone STE. Finally, we will examine any possible signature of increased ozone STE in the troposphere using sonde and tropospheric ozone residual (TOR) data, and output from the Global Modeling Initiative Chemistry Transport Model (GMI CTM).

  6. Modeling the impact of land surface feedbacks on post landfall tropical cyclones

    Science.gov (United States)

    Subramanian, Subashini

    The land surface is an important component of numerical models. The land surface models are modules that control energy partitioning, compute surface exchange coefficients and form the only physical boundary in a regional scale numerical model. Thus, an accurate representation of land surface is critical to compute surface fluxes, represent the boundary layer evolution and affect changes in weather systems. Land surface can affect landfalling tropical cyclones in two ways: (i) when the cyclone is offshore and land can influence cyclones by introducing dry (or moist) air that can weaken (or strengthen) the organized convective structure of cyclones, and (ii) land can affect the evolution of cyclones post landfall by modifying the surface heat fluxes and introducing additional surface drag. In this dissertation, the hypothesis that improved representation of land surface conditions will improve the prediction of landfalling tropical cyclones is tested. To that effect, a comprehensive review of land surface effects on tropical cyclones was undertaken and an idealized study was conducted to study the impact of antecedent soil temperature on the sustenance/reintensification of tropical cyclones over land. Rainfall verification for cyclone events over the Atlantic Ocean was conducted and a comparison study between land models--GFDL Slab and Noah, also considers the sensitivity of tropical cyclone models to land surface parameterizations. The recent adoption of Noah land model with hydrology products in HWRF offers a unique opportunity to couple a river routing model to HWRF to provide streamflow estimations from the HWRF model and this dissertation has outlined techniques to real time predict streamflow for United States with HWRF forcing. Results from this dissertation research indicate antecedent land surface conditions can affect tropical cyclone evolution post landfall and high soil temperature and thermally diffusive soil texture of land surface are critical factors

  7. Extreme weather: Subtropical floods and tropical cyclones

    Science.gov (United States)

    Shaevitz, Daniel A.

    Extreme weather events have a large effect on society. As such, it is important to understand these events and to project how they may change in a future, warmer climate. The aim of this thesis is to develop a deeper understanding of two types of extreme weather events: subtropical floods and tropical cyclones (TCs). In the subtropics, the latitude is high enough that quasi-geostrophic dynamics are at least qualitatively relevant, while low enough that moisture may be abundant and convection strong. Extratropical extreme precipitation events are usually associated with large-scale flow disturbances, strong ascent, and large latent heat release. In the first part of this thesis, I examine the possible triggering of convection by the large-scale dynamics and investigate the coupling between the two. Specifically two examples of extreme precipitation events in the subtropics are analyzed, the 2010 and 2014 floods of India and Pakistan and the 2015 flood of Texas and Oklahoma. I invert the quasi-geostrophic omega equation to decompose the large-scale vertical motion profile to components due to synoptic forcing and diabatic heating. Additionally, I present model results from within the Column Quasi-Geostrophic framework. A single column model and cloud-revolving model are forced with the large-scale forcings (other than large-scale vertical motion) computed from the quasi-geostrophic omega equation with input data from a reanalysis data set, and the large-scale vertical motion is diagnosed interactively with the simulated convection. It is found that convection was triggered primarily by mechanically forced orographic ascent over the Himalayas during the India/Pakistan flood and by upper-level Potential Vorticity disturbances during the Texas/Oklahoma flood. Furthermore, a climate attribution analysis was conducted for the Texas/Oklahoma flood and it is found that anthropogenic climate change was responsible for a small amount of rainfall during the event but the

  8. 2003 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2003 Tropical Cyclones of the World poster. During calendar year 2003, fifty-one tropical cyclones with sustained surface winds of at least 64 knots were...

  9. Year 2001 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2001 Tropical Cyclones of the World poster. During calendar year 2001, fifty tropical cyclones with sustained surface winds of at least 64 knots were observed...

  10. Year 2000 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2000 Tropical Cyclones of the World poster. During calendar year 2000, forty-five tropical cyclones with sustained surface winds of at least 64 knots were...

  11. Comparing hurricane and extratropical storm surge for the Mid-Atlantic and Northeast Coast of the United States for 1979-2013

    Science.gov (United States)

    Booth, J. F.; Rieder, H. E.; Kushnir, Y.

    2016-09-01

    This letter examines the magnitude, spatial footprint, and paths of hurricanes and extratropical cyclones (ETCs) that caused strong surge along the east coast of the US between 1979 and 2013. Lagrangian cyclone track information, for hurricanes and ETCs, is used to associate surge events with individual storms. First, hurricane influence is examined using ranked surged events per site. The fraction of hurricanes among storms associated with surge decreases from 20%-60% for the top 10 events to 10%-30% for the top 50 events, and a clear latitudinal gradient of hurricane influence emerges for larger sets of events. Secondly, surges on larger spatial domains are examined by focusing on storms that cause exceedance of the probabilistic 1-year surge return level at multiple stations. Results show that if the strongest events in terms of surge amplitude and spatial extent are considered, then hurricanes are most likely to create the hazards. However, when slightly less strong events that still impact multiple areas during the storm life cycle are considered, the relative importance of hurricanes shrinks as that of ETCs grows. Furthermore we find distinct paths for ETCs causing multi-site surge at individual segments of the US east coast.

  12. Promoting the confluence of tropical cyclone research

    OpenAIRE

    Marler, Thomas E

    2015-01-01

    Contributions of biologists to tropical cyclone research may improve by integrating concepts from other disciplines. Employing accumulated cyclone energy into protocols may foster greater integration of ecology and meteorology research. Considering experienced ecosystems as antifragile instead of just resilient may improve cross-referencing among ecological and social scientists. Quantifying ecosystem capital as distinct from ecosystem services may improve integration of tropical cyclone ecol...

  13. Tropical Cyclones: Forecasting Advances, Science Opportunities and Operational Challenges

    Science.gov (United States)

    Bosart, L. F.

    2014-12-01

    Although skill in forecasting the tracks of tropical cyclones (TCs) by operational forecast centers have improved steadily over the last 25 years, corresponding forecasts of TC intensity have shown little improvement until recently. These recent improvements in TC intensity forecasts appear to be related to a combination of better data assimilation, improved physics, and increased resolution in global operational numerical weather prediction models and new knowledge gained from a variety of recent TC-related field programs such as BGRIP, IFEX,and PREDICT. The first part of this presentation will briefly review the state of the art of TC track and intensity forecasting. The bulk of this presentation will address important TC-related science and operational challenges. These challenges include: 1) determining the physical processes that govern TC clustering, mutually interacting TCs, and the existence of different TC genesis pathways, 2) establishing how tropical-midlatitude interactions associated with recurving and transitioning (extratropical transition) TCs can trigger downstream baroclinic development, the subsequent formation of eastward-propagating Rossby wave trains, and the ensuing occurrence of extreme weather events well downstream, and 3) identifying critical TC-related forecast problems such as forecasts of the timing and extent of coastal storm surges and inland flooding associated with landfalling TCs). These important science and operational challenges will be illustrated with brief case studies.

  14. The hurricane-like Mediterranean cyclone of January 1995

    Science.gov (United States)

    Pytharoulis, Ioannis; Craig, George; Ballard, Susan

    2000-09-01

    The development of a hurricane-like vortex over the Mediterranean Sea was studied using (mainly) the UK Met. Office Unified Model. The Mediterranean cyclone formed in the morning of 15 January 1995 over the sea between Greece and Sicily. Strong convection was observed prior to its genesis. During the longest part of the cyclone's lifetime, strong surface fluxes and, as a result, deep convection existed in its vicinity. Its track was influenced by the surface fluxes and the flow in the wider region. The forecast of the mesoscale and limited-area models reproduced the general characteristics of the actual system as they appeared at the surface and upper-air charts and at the satellite imagery. The investigation of the cyclone's characteristics gave strong evidence (including an ‘eye’ and a warm core) to support the initial assertion that it was similar to tropical cyclones and some polar lows. Baroclinic instability does not seem particularly important, although the cyclone formed at the edge of a baroclinic zone. A numerical experiment showed the vortex did not develop in the absence of surface heat and moisture fluxes. Another experiment showed that sensible and latent heat fluxes were equally important in its development.

  15. Archive Compiles New Resource for Global Tropical Cyclone Research

    Science.gov (United States)

    Knapp, Kenneth R.; Kruk, Michael C.; Levinson, David H.; Gibney, Ethan J.

    2009-02-01

    The International Best Track Archive for Climate Stewardship (IBTrACS) compiles tropical cyclone best track data from 11 tropical cyclone forecast centers around the globe, producing a unified global best track data set (M. C. Kruk et al., A technique for merging global tropical cyclone best track data, submitted to Journal of Atmospheric and Oceanic Technology, 2008). Best track data (so called because the data generally refer to the best estimate of a storm's characteristics) include the position, maximum sustained winds, and minimum central pressure of a tropical cyclone at 6-hour intervals. Despite the significant impact of tropical cyclones on society and natural systems, there had been no central repository maintained for global best track data prior to the development of IBTrACS in 2008. The data set, which builds upon the efforts of the international tropical forecasting community, has become the most comprehensive global best track data set publicly available. IBTrACS was created by the U.S. National Oceanic and Atmospheric Administration's National Climatic Data Center (NOAA NCDC) under the auspices of the World Data Center for Meteorology.

  16. Weak simulated extratropical responses to complete tropical deforestation

    Science.gov (United States)

    Findell, K.L.; Knutson, T.R.; Milly, P.C.D.

    2006-01-01

    The Geophysical Fluid Dynamics Laboratory atmosphere-land model version 2 (AM2/LM2) coupled to a 50-m-thick slab ocean model has been used to investigate remote responses to tropical deforestation. Magnitudes and significance of differences between a control run and a deforested run are assessed through comparisons of 50-yr time series, accounting for autocorrelation and field significance. Complete conversion of the broadleaf evergreen forests of South America, central Africa, and the islands of Oceania to grasslands leads to highly significant local responses. In addition, a broad but mild warming is seen throughout the tropical troposphere (deforested run and the control run are similar in magnitude and area to the differences between nonoverlapping segments of the control run. These simulations suggest that extratropical responses to complete tropical deforestation are unlikely to be distinguishable from natural climate variability.

  17. Some aspects of temporal structure of leading winter extratropical modes

    Science.gov (United States)

    Pastor, M. A.; Doblas-Reyes, F. J.; Casado, M. J.

    2003-04-01

    SOME ASPECTS OF TEMPORAL STRUCTURE OF LEADING WINTER EXTRATROPICAL MODES M.A.Pastor (1), F. J. Doblas-Reyes (2), M. J. Casado (1) (1) I Instituto Nacional de Meteorología, c/Leonardo Prieto Castro,8,28071 ,Madrid,Spain, a.pastor@inm.es (2) ECMWF, Shinfield Park,RG2 9AX, Reading, UK, f.doblas-reyes@ecmwf.int As a first step in the evaluation of the capability of seasonal ensemble predictions to reproduce the leading modes which dominate the extratropical northern circulation and to explore the ensemble predictability, we examine the power spectra and timescale properties of the dominant atmospheric teleconnection patterns like the North Atlantic Oscillation (NAO), the Pacific-North America (PNA) patterns, etc. using the National Centres for Environmental Prediction (NCEP) re-analyses spanning the winters of 1948-2000 over the Northern Hemisphere poleward of 20ºN. The teleconnection patterns are identified by applying a rotated principal component analysis (RPCA) to the daily unfiltered 500-hPa geopotential height field. The election of the RPCA methodology is motivated by the fact that identifies simple and unique patterns of spatial dataset variability. The temporal evolution of the selected patterns can be understood as a stochastic processes with an e-folding timescale less than 10 days. The shortness of this timescale indicates that the excitation of these teleconnection patterns is limited to a period of time limited to a few days. Then, this study shows that the selected patterns evolve on timescales less than 2 weeks in agreement with very recent published works. It is emphasized the use of daily data in order to improve our understanding of the growth and decay mechanisms of teleconnection patterns, since using monthly or seasonal data, can produce a misleading picture of the underlying dynamics of the anomalies with time scales much shorter than 2 months.

  18. The impact of extratropical warming on the tropical precipitation

    Science.gov (United States)

    Yoshimori, Masakazu; Abe-Ouchi, Ayako; Tatebe, Hiroaki; Nozawa, Toru

    2017-04-01

    From paleoclimate evidence to future climate projections, it has been reported that the asymmetric warming (or cooling) between the northern and southern hemisphere extratropics induces the meridional shift in the tropical precipitation. Such a shift is often understood by the energy-flux framework in that the extra energy is transported from more warming to less warming hemispheres through the change in the Hadley circulation. As the Hadley circulation transports energy in opposite direction to the moisture, the tropical precipitation tends to be intensified in the hemisphere of a larger warming. This framework is shown to be particularly useful for modelling results without ocean dynamical feedback. In the current study, a fully coupled atmosphere-ocean model is used to investigate the impact of extratropical warming on the tropical precipitation under the realistic RCP4.5 scenario. It is shown that the mid-high latitude warming alone in the poleward of 40° (56% global warming) can significantly affect the tropical precipitation change in the equatorward of 20° (38% hemispheric contrast) from late autumn to early winter. High-latitude warming alone affects much less. This meridional change in the tropical precipitation is largely explained by the circulation change, rather than the humidity change. The reduced northward eddy momentum and heat fluxes in the northern hemisphere induces anomalous Hadley circulation in the northern tropics. This change seems to weaken the equatorial upwelling in the Pacific, which leads to the equatorial SST rise. The equatorial sea surface warming induces the meridionally symmetric pattern of the anomalous Hadley circulation (though, asymmetric in strength), resulting in the northward migration of the tropical precipitation. The larger change in the ocean heat transport near the equator, relative to the atmosphere, requires a more refined theory than the conventional energy-flux framework.

  19. Simulation of Extreme Arctic Cyclones in IPCC AR5 Experiments

    Science.gov (United States)

    Vavrus, S. J.

    2012-12-01

    Although impending Arctic climate change is widely recognized, a wild card in its expression is how extreme weather events in this region will respond to greenhouse warming. Intense polar cyclones represent one type of high-latitude phenomena falling into this category, including very deep synoptic-scale cyclones and mesoscale polar lows. These systems inflict damage through high winds, heavy precipitation, and wave action along coastlines, and their impact is expected to expand in the future, when reduced sea ice cover allows enhanced wave energy. The loss of a buffering ice pack could greatly increase the rate of coastal erosion, which has already been increasing in the Arctic. These and related threats may amplify if extreme Arctic cyclones become more frequent and/or intense in a warming climate with much more open water to fuel them. This possibility has merit on the basis of GCM experiments, which project that greenhouse forcing causes lower mean sea level pressure (SLP) in the Arctic and a strengthening of the deepest storms over boreal high latitudes. In this study, the latest Coupled Model Intercomparison Project (CMIP5) climate model output is used to investigate the following questions: (1) What are the spatial and seasonal characteristics of extreme Arctic cyclones? (2) How well do GCMs simulate these phenomena? (3) Are Arctic cyclones already showing the expected response to greenhouse warming in climate models? To address these questions, a retrospective analysis is conducted of the transient 20th century simulations among the CMIP5 GCMs (spanning years 1850-2005). The results demonstrate that GCMs are able to reasonably represent extreme Arctic cyclones and that the simulated characteristics do not depend significantly on model resolution. Consistent with observational evidence, climate models generate these storms primarily during winter and within the climatological Aleutian and Icelandic Low regions. Occasionally the cyclones remain very intense

  20. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Directory of Open Access Journals (Sweden)

    J. L. Stith

    2011-07-01

    Full Text Available In situ airborne sampling of refractory black carbon (rBC particles and Ice Nuclei (IN was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI and the residuals were sampled by a single particle soot photometer (SP2 instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here −24 to −29 °C, IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass

  1. Observations of ice nuclei and heterogeneous freezing in a Western Pacific extratropical storm

    Science.gov (United States)

    Stith, J. L.; Twohy, C. H.; Demott, P. J.; Baumgardner, D.; Campos, T.; Gao, R.; Anderson, J.

    2011-07-01

    In situ airborne sampling of refractory black carbon (rBC) particles and Ice Nuclei (IN) was conducted in and near an extratropical cyclonic storm in the western Pacific Ocean during the Pacific Dust Experiment, PACDEX, in the spring of 2007. Airmass origins were from Eastern Asia. Clouds associated primarily with the warm sector of the storm were sampled at various locations and altitudes. Cloud hydrometeors were evaporated by a counterflow virtual impactor (CVI) and the residuals were sampled by a single particle soot photometer (SP2) instrument, a continuous flow diffusion chamber ice nucleus detector (CFDC) and collected for electron microscope analysis. In clouds containing large ice particles, multiple residual particles were observed downstream of the CVI for each ice particle sampled on average. The fraction of rBC compared to total particles in the residual particles increased with decreasing condensed water content, while the fraction of IN compared to total particles did not, suggesting that the scavenging process for rBC is different than for IN. In the warm sector storm midlevels at temperatures where heterogeneous freezing is expected to be significant (here -24 to -29 °C), IN concentrations from ice particle residuals generally agreed with simultaneous measurements of total ice concentrations or were higher in regions where aggregates of crystals were found, suggesting heterogeneous freezing as the dominant ice formation process in the mid levels of these warm sector clouds. Lower in the storm, at warmer temperatures, ice concentrations were affected by aggregation and were somewhat less than measured IN concentrations at colder temperatures. The results are consistent with ice particles forming at storm mid-levels by heterogeneous freezing on IN, followed by aggregation and sedimentation to lower altitudes. Compositional analysis of the aerosol and back trajectories of the air in the warm sector suggested a possible biomass burning source for much

  2. Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tides, extra-tropical storm surges and mean sea level

    Science.gov (United States)

    Haigh, Ivan D.; Wijeratne, E. M. S.; MacPherson, Leigh R.; Pattiaratchi, Charitha B.; Mason, Matthew S.; Crompton, Ryan P.; George, Steve

    2014-01-01

    The occurrence of extreme water levels along low-lying, highly populated and/or developed coastlines can lead to considerable loss of life and billions of dollars of damage to coastal infrastructure. Therefore it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood management, engineering and future land-use planning. This ensures the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. This paper estimates for the first time present day extreme water level exceedence probabilities around the whole coastline of Australia. A high-resolution depth averaged hydrodynamic model has been configured for the Australian continental shelf region and has been forced with tidal levels from a global tidal model and meteorological fields from a global reanalysis to generate a 61-year hindcast of water levels. Output from this model has been successfully validated against measurements from 30 tide gauge sites. At each numeric coastal grid point, extreme value distributions have been fitted to the derived time series of annual maxima and the several largest water levels each year to estimate exceedence probabilities. This provides a reliable estimate of water level probabilities around southern Australia; a region mainly impacted by extra-tropical cyclones. However, as the meteorological forcing used only weakly includes the effects of tropical cyclones, extreme water level probabilities are underestimated around the western, northern and north-eastern Australian coastline. In a companion paper we build on the work presented here and more accurately include tropical cyclone-induced surges in the estimation of extreme water level. The multi-decadal hindcast generated here has been used primarily to estimate extreme water level exceedance probabilities but could be used more widely in the future for a variety of other research and practical

  3. Classic Maya civilization collapse associated with reduction in tropical cyclone activity

    Science.gov (United States)

    Medina, M. A.; Polanco-Martinez, J. M.; Lases-Hernández, F.; Bradley, R. S.; Burns, S. J.

    2013-12-01

    In light of the increased destructiveness of tropical cyclones observed over recent decades one might assume that an increase and not a decrease in tropical cyclone activity would lead to societal stress and perhaps collapse of ancient cultures. In this study we present evidence that a reduction in the frequency and intensity of tropical Atlantic cyclones could have contributed to the collapse of the Maya civilization during the Terminal Classic Period (TCP, AD. 800-950). Statistical comparisons of a quantitative precipitation record from the Yucatan Peninsula (YP) Maya lowlands, based on the stalagmite known as Chaac (after the Mayan God of rain and agriculture), relative to environmental proxy records of El Niño/Southern Oscillation (ENSO), tropical Atlantic sea surface temperatures (SSTs), and tropical Atlantic cyclone counts, suggest that these records share significant coherent variability during the TCP and that summer rainfall reductions between 30 and 50% in the Maya lowlands occurred in association with decreased Atlantic tropical cyclones. Analysis of modern instrumental hydrological data suggests cyclone rainfall contributions to the YP equivalent to the range of rainfall deficits associated with decreased tropical cyclone activity during the collapse of the Maya civilization. Cyclone driven precipitation variability during the TCP, implies that climate change may have triggered Maya civilization collapse via freshwater scarcity for domestic use without significant detriment to agriculture. Pyramid in Tikal, the most prominent Maya Kingdom that collapsed during the Terminal Classic Period (circa C.E. 800-950) Rainfall feeding stalagmites inside Rio Secreto cave system, Yucatan, Mexico.

  4. Tropical cyclone hazards analysis based on tropical cyclone potential impact index

    Institute of Scientific and Technical Information of China (English)

    XIAO Fengjin; YIN Yizhou; LUO Yong; SONG Lianchun; YE Dianxiu

    2011-01-01

    Tropical cyclone,a high energy destructive meteorological system with heavy rainfall and gale triggered massive landslides and windstorms,poses a significant threat to coastal areas.In this paper we have developed a Tropical Cyclone Potential Impact Index (TCPI) based on the air mass trajectories,disaster information,intensity,duration,and frequency of tropical cyclones.We analyzed the spatial pattern and interannual variation of the TCPI over the period 1949-2009,and taking the Super Typhoon Saomai as an example have examined the relationship between the TCPI and direct economic losses,total rainfall,and maximum wind speed.The results reveal that China's TCPI appears to be a weak decreasing trend over the period,which is not significant overall,but significant in some periods.Over the past 20 years,the TCPI decreased in the southern China coastal provinces of Hainan,Guangdong and Guangxi,while it increased in the southeastern coastal provinces of Zhejiang,Fujian and Taiwan.The highest values of TCPI are mainly observed in Taiwan,Hainan,the coastal areas of Guangdong and Fujian and Zhejiang's southern coast.The TCPI has a good correlation (P=0.01) with direct economic loss,rainfall,and maximum wind speed.

  5. Wind waves in tropical cyclones: satellite altimeter observations and modeling

    Science.gov (United States)

    Golubkin, Pavel; Kudryavtsev, Vladimir; Chapron, Bertrand

    2016-04-01

    Results of investigation of wind-wave generation by tropical cyclones using satellite altimeter data are presented. Tropical cyclones are generally relatively small rapidly moving low pressure systems that are capable of generating severe wave conditions. Translation of a tropical cyclone leads to a prolonged period of time surface waves in the right sector remain under high wind forcing conditions. This effect has been termed extended fetch, trapped fetch or group velocity quasi-resonance. A tropical cyclone wave field is thus likely more asymmetrical than the corresponding wind field: wind waves in the tropical cyclone right sector are more developed with larger heights than waves in the left one. A dataset of satellite altimeter intersections of the Western Pacific tropical cyclones was created for 2010-2013. Data from four missions were considered, i.e., Jason-1, Jason-2, CryoSat-2, SARAL/AltiKa. Measurements in the rear-left and front-right sectors of tropical cyclones were examined for the presence of significant wave asymmetry. An analytical model is then derived to efficiently describe the wave energy distribution in a moving tropical cyclone. The model essentially builds on a generalization of the self-similar wave growth model and the assumption of a strongly dominant single spectral mode in a given quadrant of the storm. The model provides a criterion to anticipate wave enhancement with the generation of trapped abnormal waves. If forced during a sufficient timescale interval, also defined from this generalized self-similar wave growth model, waves can be trapped and large amplification of the wave energy will occur in the front-right storm quadrant. Remarkably, the group velocity and corresponding wavelength of outrunning wave systems will become wind speed independent and solely relate to the translating velocity. The resulting significant wave height also only weakly depends on wind speed, and more strongly on the translation velocity. Satellite

  6. Training on Eastern Pacific tropical cyclones for Latin American students

    Science.gov (United States)

    Farfán, L. M.; Raga, G. B.

    2009-05-01

    Tropical cyclones are one of the most impressive atmospheric phenomena and their development in the Atlantic and Eastern Pacific basins has potential to affect several Latin-American and Caribbean countries, where human resources are limited. As part of an international research project, we are offering short courses based on the current understanding of tropical cyclones in the Eastern Pacific basin. Our main goal is to train students from higher-education institutions from various countries in Latin America. Key aspects are tropical cyclone formation and evolution, with particular emphasis on their development off the west coast of Mexico. Our approach includes lectures on tropical cyclone climatology and formation, dynamic and thermodynamic models, air-sea interaction and oceanic response, ocean waves and coastal impacts as well as variability and climate-related predictions. In particular, we use a best-track dataset issued by the United States National Hurricane Center and satellite observations to analyze convective patterns for the period 1970-2006. Case studies that resulted in landfall over northwestern Mexico are analyzed in more detail; this includes systems that developed during the 2006, 2007 and 2008 seasons. Additionally, we have organized a human-dimensions symposium to discuss socio-economic issues that are associated with the landfall of tropical cyclones. This includes coastal zone impact and flooding, the link between cyclones and water resources, the flow of weather and climate information from scientists to policy- makers, the role of emergency managers and decision makers, impact over health issues and the viewpoint of the insurance industry.

  7. DEMONSTRATION BULLETIN: CYCLONE FURNACE SOIL VITRI- FICATION TECHNOLOGY - BABCOCK & WILCOX

    Science.gov (United States)

    Babcock and Wilcox's (B&W) cyclone furnace is an innovative thermal technology which may offer advantages in treating soils containing organics, heavy metals, and/or radionuclide contaminants. The furnace used in the SITE demonstration was a 4- to 6-million Btu/hr pilot system....

  8. Corruption in cyclone preparedness and relief efforts in coastal Bangladesh

    DEFF Research Database (Denmark)

    Mahmud, Tanvir; Prowse, Martin

    2012-01-01

    schemes) suffered from greater levels, and worse types, of corruption than pre-disaster interventions (such as cyclone warning systems and disaster-preparedness training). Using an asset index created using principal component analysis, the article assesses how corruption affected wealth quartiles. Ultra...

  9. Numerical simulation and observations of very severe cyclone generated surface wave fields in the north Indian Ocean

    Indian Academy of Sciences (India)

    P Sirisha; P G Remya; T M Balakrishnan Nair; B Venkateswara Rao

    2015-12-01

    Accurate wave forecast is most needed during tropical cyclones as it has adverse effects on the entire marine activities. The present work evaluates the performance of a wave forecasting system under very severe cyclonic conditions for the Indian Ocean. The wave model results are validated separately for the deep water and shallow water using in-situ observations. Satellite altimeter observations are also utilized for validation purpose. The results show that the model performance is accurate (SI < 26% and correlation > 0.9) and consistent during very severe cyclones (categories 4 and 5). The power of the cyclone waves which hit in the eastern Indian coastal region is also analysed and it reveals that the coastal region which lies on the right side of the cyclone track receives high amount wave energy throughout the cyclone period. The study also says that the abnormal waves mostly present on the right side of the track.

  10. Cyclonic multiphase flow measurement system GLCC{copyright}1 for oil well capacity evaluation; Sistema de medicion de flujo multifasico mediante tecnologia ciclonica GLCC{copyright}1 para aforo de pozos petroleros

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Alcantar, J. M; Cervantes-Martinez, G; Cruz-Maya, J. A; Hernandez-Buenfil, M. A; Ramirez-Antonio, I [Instituto Mexicano del Petroleo, Mexico, D.F, (Mexico)]. E-mail: mgodoy@imp.mx

    2008-10-15

    This paper shows the development of a portable multiphase flow measurement system based in cyclonic separation technology GLCC{copyright}1. This system is aimed for oil well measurement and was developed in three phases; the first devoted to the geometric design of a cyclonic separator by means of designs sofware GLCCV7.8 and the selection of measurement instrumentation and flux control valves. In the second phase, the automatic control system was designed for the implementation of four control strategies each one related with a possible scenario of the well behavior. The third constitutes the integration of the measurement and control devices through a user interface aimed for visualization, information processing and system's operation and control. Experimental results in oil well measurements show the efficiency and workability of the integrated system. [Spanish] En el presente trabajo se muestra el desarrollo de un sistema portatil para la medicion de flujo multifasico, basado en la tecnologia de separacion ciclonica GLCC{copyright}1 y su utilizacion el aforo de pozos petroleros. El desarrollo del sistema se compone de tres fases, la primera se orienta hacia el diseno geometrico de un separador tipo ciclonico por medio del simulador GLCCV 7.8, asi como el dimensionamiento y la seleccion de los instrumentos de medicion y valvulas de control de flujo. En la segunda fase, se lleva a cabo la etapa de diseno del control automatico del sistema, el cual se fundamenta en el desarrollo e implantacion de cuatro estrategias de control basadas en el comportamiento dinamico de las variables de produccion del pozo; la tercera fase, la constituye el desarrollo de una interfaz para la integracion y operacion conjunta de los componentes de medicion y control del sistema, asi como de visualizacion, procesamiento y almacenamiento de la informacion. Se muestran los resultados experimentales de una prueba de medicion realizada en campo, las mediciones obtenidas muestran la

  11. Paradigms for Tropical Cyclone Intensification

    Science.gov (United States)

    2014-03-01

    summarised by Willoughby (1995, his sections 2.2.2 and 2.5.2; see also Willoughby 1990b). This model invokes the axisymmetric balance theory...Emanuel 2004, Montgomery et al. 2006, Terwey and Montgomery 2008, Braun et al. 2010). Indeed, the last four authors and others have talked about...axisymmetric balance view of spin-up The applicability of the axisymmetric balance theory summarised earlier, to the revised view of tropical cyclone

  12. The Dynamics of Tropical Cyclones

    Science.gov (United States)

    2016-06-07

    elucidate the physical mechanisms underlying changes in hurricane structure and intensity, including rapid deepening and eyewall replacement cycles; 7. To...interpreted and compared. Lectures on this work have been given by the PI at James Cook University in Townsville, the Australian Bureau of Meteorology Regional...tropical cyclone confirms the dominance of horizontal eddy fluxes at early times. The physical mechanism responsible for the differences between

  13. Cyclone with boundary layer displacement

    Energy Technology Data Exchange (ETDEWEB)

    Gorton-Huelgerth, A.; Hoffmann, D.; Staudinger, G. [Technische Universitaet Graz, Graz (Austria). Inst. fuer Verfahrenstechnik, Abt. fuer Apparatebau und Mechanische Verfahrenstechnik

    1998-12-31

    In a cyclone the boundary layers at the cover plate and outside of the vortex finder are considered to affect the separation efficiency of a cyclone. To improve separation efficiency, the boundary layers at and the space between vortex finder and cover plate were investigated. Two identical cyclones, 400 mm diameter and 990 mm long were manufactured with high precision from stainless steel. One was equipped with openings for insertion of velocity probes; the opening could be closed with glass windows to allow Laser Doppler Anemometry. The other cyclone was used for testing separation efficiency. Velocity measurements by both conventional pressure probes and Laser Doppler Anemometry revealed that only a minor part of the boundary layer at the outside of the vortex finder reaches the lower end of it, because the axial velocity is slowed down drastically. Light sheet visualization showed that there exists a heavily particle loaded boundary layer at the cover plate. There are no particles at the lower part of the vortex finder. This can be explained by the radial mass exchange. The effect of vortex finder length on separation efficiency was investigated by varying the length of the vortex finder and measuring the separation efficiency using a limestone powder as test material. It was found that the separation efficiency is not sensitive to the length of the vortex finder. Particle slip increases only where the vortex finder is definitely shorter than its diameter. It was tried to improve the separation efficiency by introducing an air curtain along the vortex finder. The positive effect on separation efficiency and particle cut size is minimal. Results from velocity measurements with cylinder pressure probes in the boundary layer do not fit the results from other measurement techniques. Many older measurements were made with these probes. The conclusions drawn and the design rules deduced are to be questioned. 17 refs., 21 figs., 2 tabs.

  14. 1992 Annual Tropical Cyclone Report

    Science.gov (United States)

    1992-01-01

    The other four chapters are in prepara- tion. The chapter-by-chapter publishing format not only makes the edition and inclusion of updated information...cyclone with maximum l-minute mean sustained sur- face winds in the range of 34 to 63 kt (17 to 32 m/see), inclusive . TROPICAL UPPER-TROPOSPHERIC TROUGH...CHUNG CHENG INSTITUTE, TAIWAN CITIES SERVICES OIL GAS CORP CITY POLYTECHNIC OF HONG KONG CKJDAD UNIVERSITARIA , MEXICO CIVIL DEFENSE, BELAU CIVIL DEFENSE

  15. Lagrangian Vortices in Developing Tropical Cyclones

    Science.gov (United States)

    2015-06-25

    cyclones B. Rutherford,a* T. J. Dunkertona and M. T. Montgomeryb aNorthwest Research Associates, Redmond, WA, USA bNaval Postgraduate School, Monterey...article has been contributed to by a US Government employee and his work is in the public domain in the USA. Tracking pre-genesis tropical cyclones is...season. All of the Lagrangian coherent structures that can be identified by this field are shown for developing disturbances and mature cyclones . The

  16. Promoting the confluence of tropical cyclone research.

    Science.gov (United States)

    Marler, Thomas E

    2015-01-01

    Contributions of biologists to tropical cyclone research may improve by integrating concepts from other disciplines. Employing accumulated cyclone energy into protocols may foster greater integration of ecology and meteorology research. Considering experienced ecosystems as antifragile instead of just resilient may improve cross-referencing among ecological and social scientists. Quantifying ecosystem capital as distinct from ecosystem services may improve integration of tropical cyclone ecology research into the expansive global climate change research community.

  17. LIQUID CYCLONE CONTACTOR

    Science.gov (United States)

    Whatley, M.E.; Woods, W.M.

    1962-09-01

    This invention relates to liquid-liquid extraction systems. The invention, an improved hydroclone system, comprises a series of serially connected, axially aligned hydroclones, each of which is provided with an axially aligned overflow chamber. The chambers are so arranged that rotational motion of a fluid being passed through the system is not lost in passing from chamber to chamber; consequently, this system is highly efficient in contacting and separating two immiscible liquids. (AEC)

  18. Reduced death rates from cyclones in Bangladesh: what more needs to be done?

    Science.gov (United States)

    Haque, Ubydul; Hashizume, Masahiro; Kolivras, Korine N; Overgaard, Hans J; Das, Bivash; Yamamoto, Taro

    2012-02-01

    Tropical storms, such as cyclones, hurricanes and typhoons, present major threats to coastal communities. Around two million people worldwide have died and millions have been injured over the past two centuries as a result of tropical storms. Bangladesh is especially vulnerable to tropical cyclones, with around 718 000 deaths from them in the past 50 years. However, cyclone-related mortality in Bangladesh has declined by more than 100-fold over the past 40 years, from 500 000 deaths in 1970 to 4234 in 2007. The main factors responsible for these reduced fatalities and injuries are improved defensive measures, including early warning systems, cyclone shelters, evacuation plans, coastal embankments, reforestation schemes and increased awareness and communication. Although warning systems have been improved, evacuation before a cyclone remains a challenge, with major problems caused by illiteracy, lack of awareness and poor communication. Despite the potential risks of climate change and tropical storms, little empirical knowledge exists on how to develop effective strategies to reduce or mitigate the effects of cyclones. This paper summarizes the most recent data and outlines the strategy adopted in Bangladesh. It offers guidance on how similar strategies can be adopted by other countries vulnerable to tropical storms. Further research is needed to enable countries to limit the risks that cyclones present to public health.

  19. Landfall tropical cyclone rainstorms on the north slope of the Dabie Mountains

    Science.gov (United States)

    Huang, Z. Y.; Wang, J. Y.; Lee, C.

    2016-08-01

    The formation and development mechanism of landfall cyclone rainstorms that occur on the north slope of the Dabie Mountains were investigated by the determination of typical occurrences. Interaction between the tropical cyclone and the westerly trough was characterized by the favorable circulation backgrounds of landfall tropical cyclone rainstorms on the north slope of the Dabie Mountains. A conveyor belt was created between the easterly jet flow of the tropical cyclone and the subtropical high pressure of the western equatorial Pacific Ocean and the southerly jet flow of the westerly trough front, creating a huge amount of energy and vapor from the landfall tropical cyclone in the rainstorm area and destabilizing the stratification. These conditions were advantageous to the frontogenesis of a warm front and the development of Mesoscale convective systems (MCS) in the westerly cold air that met the inverted trough located at the northern portion of the tropical cyclone. The existence and development of the mesoscale front area in the ground provide a trigger mechanism for the rainstorm. The MCS occurred and developed in the equivalent potential temperature theta se (θse) frontal zone, which is located between the low pressure area of the typhoon and the cold air, which is located at the rear of the westerly trough. The terrain block slowed or stopped the motion of the low pressure system formed by the landfall tropical cyclone, which was conducive to the enhancement of the rainstorm.

  20. Spatial-temporal characteristics of activity frequencies of northern cyclone and southern cyclone in East Asia%东亚地区北方气旋和南方气旋活动频数的时空特征

    Institute of Scientific and Technical Information of China (English)

    王艳玲; 王黎娟

    2011-01-01

    the activity rules of extratropical cyclone in East Asia and forecasting cyclone activity.

  1. Development and Application of an Objective Tracking Algorithm for Tropical Cyclones over the North-West Pacific purely based on Wind Speeds

    Science.gov (United States)

    Befort, Daniel J.; Kruschke, Tim; Leckebusch, Gregor C.

    2017-04-01

    Tropical Cyclones over East Asia have huge socio-economic impacts due to their strong wind fields and large rainfall amounts. Especially, the most severe events are associated with huge economic losses, e.g. Typhoon Herb in 1996 is related to overall losses exceeding 5 billion US (Munich Re, 2016). In this study, an objective tracking algorithm is applied to JRA55 reanalysis data from 1979 to 2014 over the Western North Pacific. For this purpose, a purely wind based algorithm, formerly used to identify extra-tropical wind storms, has been further developed. The algorithm is based on the exceedance of the local 98th percentile to define strong wind fields in gridded climate data. To be detected as a tropical cyclone candidate, the following criteria must be fulfilled: 1) the wind storm must exist for at least eight 6-hourly time steps and 2) the wind field must exceed a minimum size of 130.000km2 for each time step. The usage of wind information is motivated to focus on damage related events, however, a pre-selection based on the affected region is necessary to remove events of extra-tropical nature. Using IBTrACS Best Tracks for validation, it is found that about 62% of all detected tropical cyclone events in JRA55 reanalysis can be matched to an observed best track. As expected the relative amount of matched tracks increases with the wind intensity of the event, with a hit rate of about 98% for Violent Typhoons, above 90% for Very Strong Typhoons and about 75% for Typhoons. Overall these results are encouraging as the parameters used to detect tropical cyclones in JRA55, e.g. minimum area, are also suitable to detect TCs in most CMIP5 simulations and will thus allow estimates of potential future changes.

  2. Tracking Surface Cyclones with Moist Potential Vorticity

    Institute of Scientific and Technical Information of China (English)

    Zuohao CAO; Da-Lin ZHANG

    2004-01-01

    Surface cyclone tracks are investigated in the context of moist potential vorticity (MPV). A prognostic equation of surface absolute vorticity is derived which provides a basis for using negative MPV (NMPV) in the troposphere as an alternative approach to track surface cyclones. An observed case study of explosive lee cyclogenesis is performed to test the effectiveness of the MPV approach. It is shown that when a surface cyclone signal is absent due to the blocking of the Rocky Mountains, the surface cyclone can be well identified by tracing the peak NMPV.

  3. Dust-infused baroclinic cyclone storm clouds: The evidence, meteorology, and some implications

    Science.gov (United States)

    Fromm, Michael; Kablick, George; Caffrey, Peter

    2016-12-01

    Desert mineral dust is a critical yet still poorly understood component of atmospheric composition, weather, and climate. Long-range transport of dust is well known, yet uncertainty persists regarding the pathway from the desert floor to the free troposphere. Here we will show that a recurrent pathway for dust into the uppermost troposphere involves passage through an extratropical baroclinic cyclonic storm. The evidence derives from a synergistic use of satellite-based, multispectral nadir-image data and lidar. The dust-infused baroclinic storm (DIBS) exhibits peculiar cirrus cloud top reflected and emitted radiance from the UV through thermal IR, involving positive UV absorbing aerosol index, muted visible reflectivity, visible cumuliform texture, and systematically intense visible lidar backscatter on a synoptic scale. Proof that the DIBS is microphysically impacted by storm-scale dust infusion is the occurrence of anomalously large daytime 3.9-11μm brightness temperature difference indicative of small ice crystals. We present multispectral snapshots of two DIBS, over two desert source regions, in comparison with a pristine baroclinic storm cloud. Each storm snapshot is presented in the context of the baroclinic cyclone's lifetime and dust source region (the Gobi desert and the Sahara). These and other cases discussed show that the DIBS is a recurring conduit for long-range transport and a natural experiment in dust-related aerosol indirect effects.

  4. Extra-tropical origin of equatorial Pacific cold bias in climate models

    Science.gov (United States)

    Burls, N.; Muir, L.; Vincent, E. M.; Fedorov, A. V.

    2015-12-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in this project). Our study investigates the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis confirms that cold SST biases within the extra-tropical Pacific translate into a cold equatorial SST bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extended extra-tropical Pacific, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical albedo and the root-mean-square-error in equatorial SSTs - a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias is to improve the representation of cloud albedo in mid-latitudes.

  5. OPTIMIZATION AND APPLICATIONS OF REVERSE-FLOW CYCLONES

    Institute of Scientific and Technical Information of China (English)

    Guogang Sun; Jianyi Chen; Mingxian Shi

    2005-01-01

    An optimum design approach to reverse-flow cyclones based on the concept of optimizing cyclone dimensions is introduced in this paper. This approach involves optimizing cyclone dimensions by categories, calculating cyclone performance by correlating similitude numbers and optimizing the combination of four cyclone parameters, D, KA,(-d- and vi, which has been proven to be applicable not only for single-stage cyclone, but also for multistage cyclone separators. Applications of the designed cyclones in FCC units and acrylonitrile reactors are also presented.

  6. Effects of Flow Parameters and Inlet Geometry on Cyclone Efficiency

    Institute of Scientific and Technical Information of China (English)

    赵兵涛

    2006-01-01

    A novel cyclone design, named converging symmetrical spiral inlet (CSSI) cyclone, is developed by improving the inlet geometry of conventional tangential single inlet (CTSI) cyclone for enhancing the physical performance of the cyclone.The collection efficiency of the CSSI cyclone is experimentally compared with the widely used CTSI cyclone. The results indicate that the CSSI cyclone provides higher collection efficiency by 5%~20% than that of the CTSI cyclone for a tested inlet velocity range of 11.99~23.85 m/s. In addition, the results of collection efficiency comparison between experimental data and theoretical model are also discussed.

  7. Corruption in cyclone preparedness and relief efforts in coastal Bangladesh

    DEFF Research Database (Denmark)

    Mahmud, Tanvir; Prowse, Martin

    2012-01-01

    This article seeks to draw possible lessons for adaptation programmes in Bangladesh by examining whether cyclone preparedness and relief interventions are subject to corrupt practices. Based on a random sample survey of 278 households, three focus-group discussions and seven key-informant intervi......This article seeks to draw possible lessons for adaptation programmes in Bangladesh by examining whether cyclone preparedness and relief interventions are subject to corrupt practices. Based on a random sample survey of 278 households, three focus-group discussions and seven key......-informant interviews, the article investigates the nature and extent of corruption in pre- and post-disaster interventions in Khulna before and after Cyclone Aila in May 2009. Ninety nine percent of households reported losses from corrupt practices. Post-disaster interventions (such as food aid and public works...... schemes) suffered from greater levels, and worse types, of corruption than pre-disaster interventions (such as cyclone warning systems and disaster-preparedness training). Using an asset index created using principal component analysis, the article assesses how corruption affected wealth quartiles. Ultra...

  8. The Physical Models of Cyclone Diplegs in Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    K.Smolders; D.Geldart; J.Baeyens

    2001-01-01

    In most industrial fluidization units, two- or three-stage cyclone systems are used to clean the product gases. To return the solids to the bed, these cyclones are fitted with diplegs. By pass of gas from the bed through the dipleg is partially overcome by the back pressure build-up in the dipleg and by adding a trickle valve at the bottom of the dipleg. Diplegs of primary cyclones, operating at a high solid loading behave differently from diplegs of secondary and tertiary cyclones which operate at low solid loading. Both types have been investigated by pressure drop measurements, visual observation and by measurements of the air flow rate flowing up the riser. The primary dipleg was also studied using electrical capacitance tomography. The results are reported hereafter and will give a first indication towards the right design of the dipleg and the selection of the trickle valve. The influence of gas flow in the dipleg on the conversion in a catalytic fluidized bed reactor is found to be negligible.

  9. Estimating Tropical Cyclone Precipitation from Station Observations

    Institute of Scientific and Technical Information of China (English)

    REN Fumin; WANG Yongmei; WANG Xiaoling; LI Weijing

    2007-01-01

    In this paper, an objective technique for estimating the tropical cyclone (TC) precipitation from station observations is proposed. Based on a comparison between the Original Objective Method (OOM) and the Expert Subjective Method (ESM), the Objective Synoptic Analysis Technique (OSAT) for partitioning TC precipitation was developed by analyzing the western North Pacific (WNP) TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM,by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation (D0) and the TC size (D1), into variable parameters.Case verification for OSAT was also carried out by applying CMORPH (Climate Prediction Center MORPHing technique) daily precipitation measurements, which is NOAA's combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.

  10. Sea surface height evidence for long-term warming effects of tropical cyclones on the ocean.

    Science.gov (United States)

    Mei, Wei; Primeau, François; McWilliams, James C; Pasquero, Claudia

    2013-09-17

    Tropical cyclones have been hypothesized to influence climate by pumping heat into the ocean, but a direct measure of this warming effect is still lacking. We quantified cyclone-induced ocean warming by directly monitoring the thermal expansion of water in the wake of cyclones, using satellite-based sea surface height data that provide a unique way of tracking the changes in ocean heat content on seasonal and longer timescales. We find that the long-term effect of cyclones is to warm the ocean at a rate of 0.32 ± 0.15 PW between 1993 and 2009, i.e., ∼23 times more efficiently per unit area than the background equatorial warming, making cyclones potentially important modulators of the climate by affecting heat transport in the ocean-atmosphere system. Furthermore, our analysis reveals that the rate of warming increases with cyclone intensity. This, together with a predicted shift in the distribution of cyclones toward higher intensities as climate warms, suggests the ocean will get even warmer, possibly leading to a positive feedback.

  11. Effect of a cyclonic flotation column on the separation of magnesium from phosphate ore

    Institute of Scientific and Technical Information of China (English)

    Li Guosheng; Liu Jiongtian; Cao Yijun; Wang Dapeng

    2011-01-01

    This study was performed to investigate the effects of the cyclonic separation mechanism on the removal of magnesium from phosphate ore.An analysis of the particle-bubble collision mechanism in a cyclonic force field was used to design two different pulp circulation systems for a cyclonic-static micro-bubble flotation column (FCSMC).Experiments comparing the two conditions were then conducted.Size analysis of the feed and separated products was conducted with a BXF cyclone size analyzer.The results show that about 34.60% of the total MgO content in the feed exists in the -10 μm fraction.This demonstrates that magnesium removal from phosphate ore has the characteristics of a micro-fine particle flotation problem.Under conditions of cyclonic circulation the MgO level of the concentrate is 1.74%,which is lower than that obtained from the column operated in direct-flow circulation by 0.34%.These results indicate that the cyclonic circulation mechanism of the FCSMC can promote removal of micro-fine particles containing magnesium.This is attributed to the function of surface flotation and to the reduction of the lower separation limit under conditions of cyclonic circulation.

  12. Transport timescales and tracer properties in the extratropical UTLS

    Directory of Open Access Journals (Sweden)

    P. Hoor

    2010-05-01

    Full Text Available A comprehensive evaluation of seasonal backward trajectories initialized in the Northern Hemisphere lowermost stratosphere (LMS has been performed to investigate the origin of air parcels and the main mechanisms determining characteristic structures in H2O and CO within the LMS. In particular we explain the fundamental role of the transit time since last tropopause crossing (tTST for the chemical structure of the LMS as well as the feature of the extra-tropical tropopause transition layer (ExTL as identified from CO profiles. The distribution of H2O in the background LMS above Θ=320 K and 340 K in northern winter and summer, respectively, is found to be governed mainly by the saturation mixing ratio, which in turn is determined by the Lagrangian Cold Point (LCP encountered by each trajectory. Most of the backward trajectories from this region in the LMS experienced their LCP in the tropics and sub-tropics. The transit time since crossing the tropopause from the troposphere to the stratosphere (tTST is independent of the H2O value of the air parcel. TST often occurs 20 days after trajectories have encountered their LCP. CO, on the other hand, depends strongly on tTST due to its finite lifetime. The ExTL as identified from CO measurements is then explained as a layer of air just above the tropopause, which on average encountered TST fairly recently.

  13. Traveling Weather Disturbances in Mars' Southern Extratropics: Sway of the Great Impact Basins

    Science.gov (United States)

    Hollingsworth, Jeffery L.

    2016-04-01

    As on Earth, between late autumn and early spring on Mars middle and high latitudes within its atmosphere support strong mean thermal contrasts between the equator and poles (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that this strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Within a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, such large-scale, extratropical weather disturbances are critical components of the global circulation. These wave-like disturbances act as agents in the transport of heat and momentum, and moreover generalized tracer quantities (e.g., atmospheric dust, water vapor and water-ice clouds) between low and high latitudes of the planet. The character of large-scale, traveling extratropical synoptic-period disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a high-resolution Mars global climate model (Mars GCM). This global circulation model imposes interactively lifted (and radiatively active) dust based on a threshold value of the instantaneous surface stress. Compared to observations, the model exhibits a reasonable "dust cycle" (i.e., globally averaged, a more dusty atmosphere during southern spring and summer occurs). In contrast to their northern-hemisphere counterparts, southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense synoptically. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather disturbances are examined. Simulations that adapt Mars' full topography compared to simulations that utilize synthetic topographies emulating essential large-scale features of the southern middle latitudes indicate that Mars

  14. The impact of the Asian summer monsoon on the composition of the extratropical lower stratosphere

    Science.gov (United States)

    Hoor, Peter; Müller, Stefan; Bozem, Heiko; Krause, Jens; Zahn, Andreas; Boenisch, Harald; Engel, Andreas; Vogel, Bärbel; Rolf, Christian; Ploeger, Felix; Krämer, Martina; Riese, Martin; Schlager, Hans

    2017-04-01

    We present tracer measurements from the German research aircraft HALO, which were obtained during the TACTS/ESMVal-project (Transport and Composition in the UT/LS and Earth System Model Validation) in September 2012 in the northern mid latitude lower stratosphere. We will focus on the distribution of CO, N2O and ozone in the extratropics between potential temperatures of 360 K and 410 K and their changes over the course of the campaign. Based on the distribution of N2O and CO, which constitute two tropospheric tracers of different lifetime one can quantify time scales of transport and chemical ageing of air masses. To account for mixing we analyze the distribution of CO relative to N2O. In geometrical coordinates we observed an increase of N2O and CO over a course of four weeks due to the increased impact of the monsoon system. When analyzing CO relative N2O to account for mixing we observe a decrease of the tropospheric fraction relative to N2O. These results are consistent with the fact that air in Asian monsoon anticyclone is trapped which allows for photochemical CO degradation. Based on the correlation of CO and N2O we estimate an upper limit for the degradation of CO relative to N2O of 30 days.

  15. Mixing in the Extratropical Stratosphere: Model-measurements Comparisons using MLM Diagnostics

    Science.gov (United States)

    Ma, Jun; Waugh, Darryn W.; Douglass, Anne R.; Kawa, Stephan R.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    We evaluate transport processes in the extratropical lower stratosphere for both models and measurements with the help of equivalent length diagnostic from the modified Lagrangian-mean (MLM) analysis. This diagnostic is used to compare measurements of long-lived tracers made by the Cryogenic Limb Array Etalon Spectrometer (CLAES) on the Upper Atmosphere Research Satellite (UARS) with simulated tracers. Simulations are produced in Chemical and Transport Models (CTMs), in which meteorological fields are taken from the Goddard Earth Observing System Data Assimilation System (GEOS DAS), the Middle Atmosphere Community Climate Model (MACCM2), and the Geophysical Fluid Dynamics Laboratory (GFDL) "SKYHI" model, respectively. Time series of isentropic equivalent length show that these models are able to capture major mixing and transport properties observed by CLAES, such as the formation and destruction of polar barriers, the presence of surf zones in both hemispheres. Differences between each model simulation and the observation are examined in light of model performance. Among these differences, only the simulation driven by GEOS DAS shows one case of the "top-down" destruction of the Antarctic polar vortex, as observed in the CLAES data. Additional experiments of isentropic advection of artificial tracer by GEOS DAS winds suggest that diabatic movement might have considerable contribution to the equivalent length field in the 3D CTM diagnostics.

  16. A comparison of tracking methods for extreme cyclones in the Arctic basin

    Directory of Open Access Journals (Sweden)

    Ian Simmonds

    2014-09-01

    Full Text Available Dramatic climate changes have occurred in recent decades over the Arctic region, and very noticeably in near-surface warming and reductions in sea ice extent. In a climatological sense, Arctic cyclone behaviour is linked to the distributions of lower troposphere temperature and sea ice, and hence the monitoring of storms can be seen as an important component of the analysis of Arctic climate. The analysis of cyclone behaviour, however, is not without ambiguity, and different cyclone identification algorithms can lead to divergent conclusions. Here we analyse a subset of Arctic cyclones with 10 state-of-the-art cyclone identification schemes applied to the ERA-Interim reanalysis. The subset is comprised of the five most intense (defined in terms of central pressure Arctic cyclones for each of the 12 calendar months over the 30-yr period from 1 January 1979 to 31 March 2009. There is a considerable difference between the central pressures diagnosed by the algorithms of typically 5–10 hPa. By contrast, there is substantial agreement as to the location of the centre of these extreme storms. The cyclone tracking algorithms also display some differences in the evolution and life cycle of these storms, while overall finding them to be quite long-lived. For all but six of the 60 storms an intense tropopause polar vortex is identified within 555 km of the surface system. The results presented here highlight some significant differences between the outputs of the algorithms, and hence point to the value using multiple identification schemes in the study of cyclone behaviour. Overall, however, the algorithms reached a very robust consensus on most aspects of the behaviour of these very extreme cyclones in the Arctic basin.

  17. Reduced models of extratropical low-frequency variability

    Science.gov (United States)

    Strounine, Kirill

    Low-frequency variability (LFV) of the atmosphere refers to its behavior on time scales of 10-100 days, longer than the life cycle of a mid-latitude cyclone but shorter than a season. This behavior is still poorly understood and hard to predict. It has been helpful in gaining understanding that might improve prediction to use various simplified models. The present study compares and contrasts various mode reduction strategies that help derive systematically such simplified models of LFV. Three major strategies have been applied to reduce a fairly realistic, high-dimensional, quasi-geostrophic, 3-level (QG3) atmospheric model to lower dimensions: (i) a purely empirical, multi-level regression procedure, which specifies the functional form of the reduced model and finds the model coefficients by multiple polynomial regression; (ii) an empirical-dynamical method, which retains only a few components in the projection of the full QG3 model equations onto a specified basis (the so-called bare truncation), and finds the linear deterministic and additive stochastic corrections empirically; and (iii) a dynamics-based technique, employing the stochastic mode reduction strategy of Majda et al. (2001; MTV). Subject to the assumption of significant time-scale separation in the physical system under consideration, MTV derives the form of the reduced model and finds its coefficients with minimal statistical fitting. The empirical-dynamical and dynamical reduced models were further improved by sequential parameter estimation and benchmarked against multi-level regression models; the extended Kalman filter (EKF) was used for the parameter estimation. In constructing the reduced models, the choice of basis functions is also important. We considered as basis functions a set of empirical orthogonal functions (EOFs). These EOFs were computed using (a) an energy norm; and (b) a potential-enstrophy norm. We also devised a method, using singular value decomposition of the full

  18. The Role of Moist Processes in the Intrinsic Predictability of Indian Ocean Cyclones

    Energy Technology Data Exchange (ETDEWEB)

    Taraphdar, Sourav; Mukhopadhyay, P.; Leung, Lai-Yung R.; Zhang, Fuqing; Abhilash, S.; Goswami, B. N.

    2014-07-16

    The role of moist processes and the possibility of error cascade from cloud scale processes affecting the intrinsic predictable time scale of a high resolution convection permitting model within the environment of tropical cyclones (TCs) over the Indian region are investigated. Consistent with past studies of extra-tropical cyclones, it is demonstrated that moist processes play a major role in forecast error growth which may ultimately limit the intrinsic predictability of the TCs. Small errors in the initial conditions may grow rapidly and cascades from smaller scales to the larger scales through strong diabatic heating and nonlinearities associated with moist convection. Results from a suite of twin perturbation experiments for four tropical cyclones suggest that the error growth is significantly higher in cloud permitting simulation at 3.3 km resolutions compared to simulations at 3.3 km and 10 km resolution with parameterized convection. Convective parameterizations with prescribed convective time scales typically longer than the model time step allows the effects of microphysical tendencies to average out so convection responds to a smoother dynamical forcing. Without convective parameterizations, the finer-scale instabilities resolved at 3.3 km resolution and stronger vertical motion that results from the cloud microphysical parameterizations removing super-saturation at each model time step can ultimately feed the error growth in convection permitting simulations. This implies that careful considerations and/or improvements in cloud parameterizations are needed if numerical predictions are to be improved through increased model resolution. Rapid upscale error growth from convective scales may ultimately limit the intrinsic mesoscale predictability of the TCs, which further supports the needs for probabilistic forecasts of these events, even at the mesoscales.

  19. Cyclone Center: Insights on Historical Tropical Cyclones from Citizen Volunteers

    Science.gov (United States)

    Thorne, P.; Hennon, C. C.; Knapp, K. R.; Schreck, C. J., III; Stevens, S. E.; Kossin, J. P.; Rennie, J.; Hennon, P. A.; Kruk, M. C.

    2015-12-01

    The cyclonecenter.org project started in fall 2012 and has been collecting citizen scientist volunteer tropical cyclone intensity estimates ever since. The project is hosted by the Citizen Science Alliance (zooniverse) and the platform is supported by a range of scientists. We have over 30 years of satellite imagery of tropical cyclones but the analysis to date has been done on an ocean-basin by ocean-basin basis and worse still practices have changed over time. We therefore do not, presently, have a homogeneous record relevant for discerning climatic changes. Automated techniques can classify many of the images but have a propensity to be challenged during storm transitions. The problem is fundamentally one where many pairs of eyes are invaluable as there is no substitute for human eyes in discerning patterns. Each image is classified by ten unique users before it is retired. This provides a unique insight into the uncertainty inherent in classification. In the three years of the project much useful data has accrued. This presentation shall highlight some of the results and analyses to date and touch on insights as to what has worked and what perhaps has not worked so well. There are still many images left to complete so its far from too late to jump over to www.cyclonecenter.org and help out.

  20. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sarv, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1991-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  1. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Farzan, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1990-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  2. Annual Tropical Cyclone Report, 1984.

    Science.gov (United States)

    1984-01-01

    compares COSM to OTCM, i.e. in the 461 cases available for a (homogeneous) (12) Dvorak -- An estimation of a comparison, the average vector error at...TOTL - TOTAL (TYAN 78) COSM - CosMOS (MOS) CLIP 322 232 323 280 344 262 NTCM - NESTLD TROPICAL CYCLONE MODEL 255 23 258 -21 262 0 OTCH - ONE-WAY...BILL CECIL CARMEN CARY CLARA DOT DON DINAH DOYLE ELLIS ELLEN ED ELSIE FAYE FORREST FREDA FABIAN GORDON GEORGIA GERALD GAY HOPE HERBERT HOLLY HAL

  3. Annual Tropical Cyclone Report 1980

    Science.gov (United States)

    1980-01-01

    old global band prognos- TROPICAL CYCLONE HAVEN STUDIES tic fields because the tau zero analysis is not available until several hours past warn...fore- In addition, COMSECONDFLT and CINCLANTFLT casts are now being recomputed with tau zero have requested 22 ports and harbors in the analyses...34 PCh 5 T2.".2.5 .𔃿B.S,24HRS HOBB6 KJl1 lB 171539 17.eH 67.2E PEN 6 HOARS KGUW II 188418 I8.SN 67.5E PEN 6 TI.5/2.5 AII./24HRS HORAS KGLC 12 .81516 18

  4. Understanding the impact of extra-tropical storms from CORDEX projections over the Scandinavian coast

    Science.gov (United States)

    Veldore, Vidyunmala; Luna, Byron Quan

    2017-04-01

    Response of extra-tropical storms to climate change over the Scandinavian coast in high resolution regional climate projection is investigated in the current study. The complex interactions between North Atlantic oscillation, arctic amplification, ocean-atmospheric interactions and changing nature of synoptic waves will affect the generation and extremity of storm types. The nature of these storms is dependent on large-scale systems over this region, and hence higher resolution climate models might be able to represent the structure and intensity of the storms with accuracy. We propose a tracking algorithm for two seasons autumn (September-October-November) and winter season (December-January-February) providing features to detect the frequency and intensity of storm types for a given coast. Our objective is to understand the impact of changing nature of extreme storm types over the Scandinavian coast. Using a spatial assessment, possible impacts due to future storms in RCP8.5 scenario are assessed and hazard levels are represented.

  5. Shift of extreme spring streamflow on the Belorussian rivers and its association with changes of cyclonic activity over Eastern Europe

    Science.gov (United States)

    Partasenok, Irina; Chekan, Gregory

    2014-05-01

    The intra-annual distribution of precipitation is the most variable component of the water resources of Belarus. This distribution is controlled by extratropical cyclones from the Atlantic Ocean and Mediterranean that bring most of precipitation to the nation. That's why the aim of our study was to quantify major characteristics of these cyclones and to estimate effects of their passing through the Belorussian territory on regional water budget including floods and low water conditions. We documented the long-term fluctuations of streamflow and occurrence of extreme phenomena on the rivers of Belarus during the post-World War II period. It was established that annual water budget of the nation vary from year to year without systematic tendencies. At the same time, analysis of intra-annual distribution of streamflow reveals significant changes since the 1970s: increase of winter and decrease of spring runoff. As a result, the frequency of extreme spring floods has decreased. These changes in water regime are associated with climatic anomalies caused by large-scale alterations in atmospheric circulation, specifically in trajectories of cyclones. As a manifestation of these circulation changes, we observe increase of the surface air temperatures, more frequent cold season thaws, redistribution of seasonal precipitation totals, and decrease of the fraction of frozen precipitation in the shoulder seasons. Analysis of cyclonic activity over Belarus during the past 60 years in the cold season (December through February) shows the largest number of cyclones in 1950-1970. During this period, the largest number of spring floods caused by snowmelt on the rivers of Belarus was reported. Since 1970, we observe a decrease in the total number of cyclones but also an increasing strength (deepening) of the remaining cyclones in the cold season. That has led to some precipitation increase. During the last four decades, more frequent zonal air movement in the atmosphere and

  6. The great 2012 Arctic Ocean summer cyclone enhanced biological productivity on the shelves.

    Science.gov (United States)

    Zhang, Jinlun; Ashjian, Carin; Campbell, Robert; Hill, Victoria; Spitz, Yvette H; Steele, Michael

    2014-01-01

    [1] A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and phytoplankton biomass by up to 40% in the wake of the cyclone. The increase in zooplankton biomass is up to 18% on 31 August and remains 10% on 15 September, more than 1 month after the storm. In the central PSA, however, model simulations indicate a decrease in PP and plankton biomass. The biological gain on the shelves and loss in the central PSA are linked to two factors. (1) The cyclone enhances mixing in the upper ocean, which increases nutrient availability in the surface waters of the shelves; enhanced mixing in the central PSA does not increase productivity because nutrients there are mostly depleted through summer draw down by the time of the cyclone's passage. (2) The cyclone also induces divergence, resulting from the cyclone's low-pressure system that drives cyclonic sea ice and upper ocean circulation, which transports more plankton biomass onto the shelves from the central PSA. The simulated biological gain on the shelves is greater than the loss in the central PSA, and therefore, the production on average over the entire PSA is increased by the cyclone. Because the gain on the shelves is offset by the loss in the central PSA, the average increase over the entire PSA is moderate and lasts only about 10 days. The generally positive impact of cyclones on the marine ecosystem in the Arctic, particularly on the shelves, is likely to grow with increasing

  7. Seasonal variability of tropical cyclones generated over the South China Sea

    Institute of Scientific and Technical Information of China (English)

    WANG Guihua; WANG Hui; QI Yiquan

    2007-01-01

    The seasonal variability of tropical cyclones (CTCs) generated over the South China Sea (SCS) from 1948 to 2003 is analyzed. It peaks in occurrence in August and few generate in late winter (from January to March). The seasonal activity is attributed to the variability of atmosphere and ocean environments associated with the monsoon system. It is found that the monsoonal characteristics of the SCS basically determine the region of tropical cyclone (TC) genesis in each month.

  8. Topographic effects on polar low and tropical cyclone development in simple theoretical model

    Institute of Scientific and Technical Information of China (English)

    Zi-liang LI; Gang FU; Jing-tian GUO; Yi-hong DUAN; Mei-gen ZHANG

    2009-01-01

    The polar low and tropical cyclone type vortices over topography are assumed to be the axisymmetrical and thermal-wind balanced systems, which are solved as an initial value problem of a linearized vortex equation set in cylindrical coordinates. The roles of the sensible and latent heating, friction, and topography in the structure and intensification of the polar low and tropical cyclone type vortices are analyzed. The radial velocity, vertical velocity, azimuthal velocity, and the unstable growth rate including the topography effects are obtained. It is shown that the interaction between the flow and the topography plays a significant role in the structure and intensification of the polar low and tropical cyclone system. The analysis of the topography term indicates that, in the up-slope side of the mountain, the radial inflow and the vertical ascent forced by the mountain can intensify the polar low and tropical cyclone type vortex and increase the unstable growth rate. However, in the lee side of the mountain, the radial inflow and the vertical descent forced by the mountain can weaken the polar low and tropical cyclone type vortex and decrease the unstable growth rate of the polar low and tropical cyclone system. In addition, the evolutionary process and the spatial structure of the polar low observed over the Japan Sea on 19 December 2003 are investigated with the observationaldata to verify this theoretical result.

  9. Advantages and risks in increasing cyclone separator length

    NARCIS (Netherlands)

    Hoffmann, AC; de Groot, M; Peng, W; Dries, HWA; Kater, J

    2001-01-01

    The effect of cyclone length on separation efficiency and pressure drop has been investigated experimentally and theoretically by varying the length of the cylindrical segment of a cylinder-on-cone cyclone. Experimental results based on cyclone lengths from 2.65 to 6.15 cyclone diameters showed a ma

  10. An economic assessment of tropical cyclone risk on offshore wind farms

    DEFF Research Database (Denmark)

    Hong, Lixuan; Möller, Bernd

    2012-01-01

    Frequent tropical cyclones pose great risks and obstacles to the development of offshore wind farms in the coastal regions of China and other areas in the Pacific, where development of wind energy is gaining momentum. This paper aims to identify and evaluate the economic risks of tropical cyclones...... on offshore wind farms within the Economic Exclusive Zone (EEZ) of China and help improve decision-making for planners and investors. The risks of tropical cyclone impact in this paper are defined by the statistical extreme wind climate and the annual expected economic losses of offshore wind farms....... A probabilistic tropical cyclone event model is applied to evaluate 20-year, 30-year, 50-year and 100-year recurrence of extreme wind speeds by geographical location. Combining a damage model derived from empirical loss data and an investment cost model within a Geographical Information System (GIS), the annual...

  11. A field theoretical prediction of the tropical cyclone properties

    CERN Document Server

    Spineanu, Florin

    2013-01-01

    The large scale atmospheric vortices (tropical cyclones, tornadoes) are complex physical systems combining thermodynamics and fluid-mechanical processes. The late phase of the evolution towards stationarity consists of the vorticity concentration, a well known tendency to self-organization, an universal property of the two-dimensional fluids. It may then be expected that the stationary state of the tropical cyclone has the same nature as the vortices of many other systems in nature: ideal (Euler) fluids, superconductors, Bose - Einsetin condensate, cosmic strings, etc. Indeed it was found that there is a description of the atmospheric vortex in terms of a field theory. It is compatible with the more conventional treatment based on conservation laws, but the field theoretical model reveals properties that are almost inaccessible to the conventional formulation: it identifies the stationary states as being close to self-duality. This is of highest importance: the self-duality is known to be the origin of all co...

  12. Assessment of Mediterranean cyclones in the multi-ensemble EC-Earth

    Science.gov (United States)

    Gil, Victoria; Liberato, Margarida L. R.; Trigo, Isabel F.; Trigo, Ricardo M.

    2015-04-01

    The geographical location and characteristics of the Mediterranean basin make this a particularly active region in terms of cyclone forming and re-development (Trigo et al., 2002). The area is affected by moving depressions, most originated over the North Atlantic, which may later be forced by the orography surrounding the Mediterranean Sea and enhanced by the local source of moisture and heat fluxes over the Sea itself. The present work analyses the response of Mediterranean cyclones to climate change by means of 7 ensemble members of EC-EARTH model from CMIP5 (Fifth Coupled Model Intercomparison Project). We restrict the analysis to a relatively small subset (7 members) of the total number of ensemble members available in order to take into account only the members present in the three selected experiments for robust detection of extra-tropical cyclones in the Mediterranean (Trigo, 2006). We have applied the standard procedure by comparing a common 25-year period of the historical (1980-2004), present day simulations, and the future climate simulations (2074-2098) forced by RCP4.5 and RCP8.5 scenarios. The study area corresponds to the window between 10°W-42°E and 27°N-48°N. The analysis is performed with a focus in spatial distribution density and main characteristics of the overall cyclones for winter (DJF) and summer (JJA) seasons. Despite the discrepancies in cyclone numbers when compared with the ERA Interim common period (reducing to only 72% in DJF and 78% in JJA), the ensemble average matches relatively well the main spatial patterns of areas. Results indicate that the ensemble average is characterized by a small decrease in winter (-3%) and a notable increase in summer (+10%) in total number of cyclones and that the individual ensemble members reveal small spread. Such tendency is particularly pronounced under the high RCP8.5 emission scenario being more moderated under the RCP4.5 scenario. Additionally, an assessment of changes in the annual cycle

  13. Asymmetric and axisymmetric dynamics of tropical cyclones

    Directory of Open Access Journals (Sweden)

    J. Persing

    2013-05-01

    Full Text Available We present the results of idealized numerical experiments to examine the difference between tropical cyclone evolution in three-dimensional (3-D and axisymmetric (AX model configurations. We focus on the prototype problem for intensification, which considers the evolution of an initially unsaturated AX vortex in gradient-wind balance on an f-plane. Consistent with findings of previous work, the mature intensity in the 3-D model is reduced relative to that in the AX model. In contrast with previous interpretations invoking barotropic instability and related horizontal mixing processes as a mechanism detrimental to the spin-up process, the results indicate that 3-D eddy processes associated with vortical plume structures can assist the intensification process by contributing to a radial contraction of the maximum tangential velocity and to a vertical extension of tangential winds through the depth of the troposphere. These plumes contribute significantly also to the azimuthally-averaged heating rate and the corresponding azimuthal-mean overturning circulation. The comparisons show that the resolved 3-D eddy momentum fluxes above the boundary layer exhibit counter-gradient characteristics and are generally not represented properly by the subgrid-scale parameterizations in the AX configuration. The resolved eddy fluxes act to support the contraction and intensification of the maximum tangential winds. The comparisons indicate fundamental differences between convective organization in the 3-D and AX configurations for meteorologically relevant forecast time scales. While the radial and vertical gradients of the system-scale angular rotation provide a hostile environment for deep convection in the 3-D model, with a corresponding tendency to strain the convective elements in the tangential direction, deep convection in the AX model does not suffer this tendency. Also, since during the 3-D intensification process the convection has not yet organized

  14. Vertical transport of ozone and CO during super cyclones in the Bay of Bengal as detected by Tropospheric Emission Spectrometer.

    Science.gov (United States)

    Fadnavis, S; Beig, G; Buchunde, P; Ghude, Sachin D; Krishnamurti, T N

    2011-02-01

    Vertical profiles of carbon monoxide (CO) and ozone retrieved from Tropospheric Emission Spectrometer have been analyzed during two super cyclone systems Mala and Sidr. Super cyclones Mala and Sidr traversed the Bay of Bengal (BOB) region on April 24-29, 2006 and November 12-16, 2007 respectively. The CO and ozone plume is observed as a strong enhancement of these pollutants in the upper troposphere over the BOB, indicating deep convective transport. Longitude-height cross-section of these pollutants shows vertical transport to the upper troposphere. CO mixing ratio ~90 ppb is observed near the 146-mb level during the cyclone Mala and near 316 mb during the cyclone Sidr. Ozone mixing ratio ~60-100 ppb is observed near the 316-mb level during both the cyclones. Analysis of National Centers for Environmental Prediction (NCEP) reanalysis vertical winds (omega) confirms vertical transport in the BOB.

  15. Post Cyclone (PoC) : An innovative way to reduce the emission of fines from industrial cyclones

    NARCIS (Netherlands)

    Ray - Bhowmick, Madhumita; Luning, P.E.; Hoffmann, A.C; Plomp, A.; Beumer, M.I.L.

    A novel approach for reducing the emission of industrial-scale cyclones of particles smaller than 10 mu m is presented. Utilizing the strong swirl already present in the vortex finder of a conventional cyclone, the escaped dust from the cyclone is collected in a so-called ''Post Cyclone'' (PoC),

  16. Post Cyclone (PoC) : An innovative way to reduce the emission of fines from industrial cyclones

    NARCIS (Netherlands)

    Ray, MB; Luning, PE; Hoffmann, AC; Plomp, A; Beumer, MIL

    1997-01-01

    A novel approach for reducing the emission of industrial-scale cyclones of particles smaller than 10 mu m is presented. Utilizing the strong swirl already present in the vortex finder of a conventional cyclone, the escaped dust from the cyclone is collected in a so-called ''Post Cyclone'' (PoC), whi

  17. Innovative software facilitates cyclone tracking and analysis

    Science.gov (United States)

    Grigoriev, Sergey; Gulev, Sergey; Zolina, Olga

    The need for research and development of new cost-efficient methods for tracking and analyzing atmospheric cyclones is apparent. Currently storm tracking is performed either manually or using numerical codes. The manual approach is more accurate but it requires considerable time and labor. Numerical schemes [e.g., Murray and Simmonds, 1991] track the cyclones from digital sea level pressure (SLP) data, linking the sequential positions of cyclone centers using different assumptions based on atmospheric dynamics. This approach is very effective computationally but it creates a number of uncertainties and biases, especially in the Northern Hemisphere.

  18. Tropical cyclone statistics in the Northeastern Pacific

    OpenAIRE

    Romero Vadillo, E; Zaitsev, Oleg; Morales Pérez., R

    2007-01-01

    The principal area of tropical cyclogenesis in the tropical eastern Pacific Ocean is offshore in the Gulf of Tehuantepec, between 8 and 15° N, and most of these cyclones move towards the west and northwest during their initial phase. Historical analysis of tropical cyclone data in the Northeastern (NE) Pacific over the last 38 years (from 1966 to 2004) shows a mean of 16.3 tropical cyclones per year, consisting of 8.8 hurricanes and 7.4 tropical storms. The analysis shows great geographical v...

  19. Interactions between clouds and atmospheric circulation in the extratropics

    Science.gov (United States)

    Ceppi, Paulo

    In climate models, the simulation of clouds is known to be particularly problematic, leading to important biases in the climatological energy balance on regional scales, as well as to large uncertainties in the future amount of warming in response to greenhouse gas increase. This thesis explores the connections between clouds and atmospheric circulation in extratropical regions. In particular, we investigate the impacts of clouds and their uncertainties on atmospheric circulation and its response to global warming. We find that clouds have very substantial effects both on the mean circulation and on its future response to warming in climate models. In the mean state, the position of the midlatitude jet correlates well with the midlatitude shortwave cloud-radiative effect (SW CRE), which suffers from very large biases in models. Models in which midlatitude SW CRE is too negative have anomalously cold midlatitudes, leading to an anomalously equatorward jet position. This result is supported by idealized model experiments and appears consistent with the effect of midlatitude baroclinicity changes on eddy activity. This means that an accurate representation of clouds and their radiative effects is essential to correctly portray the mean circulation. In the context of greenhouse gas--forced change, we demonstrate that cloud-radiative changes have a surprisingly large impact on the atmospheric circulation response. This results mainly from the SW cloud feedback, whose specific spatial structure induces low-latitude warming and high-latitude cooling, enhancing midlatitude baroclinicity and favoring a strengthening and poleward shift of the midlatitude jet. This opposes the effects of other major feedbacks (e.g., the water vapor feedback and the longwave cloud feedback), which produce polar-amplified warming and weakened midlatitude baroclinicity. For this reason, cloud-radiative changes explain the majority of the poleward expansion of atmospheric circulation in our model

  20. CO2 and albedo climate impacts of extratropical carbon and biomass plantations

    NARCIS (Netherlands)

    Schaeffer, M.; Eickhout, B.; Hoogwijk, M.; Strengers, B.; Vuuren, van D.J.; Leemans, R.; Opsteegh, T.

    2006-01-01

    We explored the climate impacts for two land-use change scenarios, aimed at mitigating the buildup of greenhouse gases in the atmosphere. Using the integrated assessment model IMAGE 2.2, we found that the large-scale implementation in the extratropics of either carbon-sequestration or modern-biomass

  1. 76 FR 74776 - Forum-Trends in Extreme Winds, Waves, and Extratropical Storms Along the Coasts

    Science.gov (United States)

    2011-12-01

    ... National Oceanic and Atmospheric Administration Forum--Trends in Extreme Winds, Waves, and Extratropical... open public forum. SUMMARY: This notice sets forth the schedule and topics of an upcoming forum hosted... the forum and are required to RSVP to Brooke.Stewart@noaa.gov by 5 p.m. EST, Wednesday, December 28...

  2. Verification of tropical cyclone using the KIAPS Integration Model (KIM)

    Science.gov (United States)

    Lim, S.; Seol, K. H.

    2015-12-01

    The Korea Institute of Atmospheric Prediction Systems (KIAPS) is a government funded non-profit research and development institute located in Seoul, South Korea. KIAPS is developing the Global Model, a backbone for the next-generation operational global numerical weather prediction (NWP) system with three-phase plans; Establishment and R&D Planning (2011-2013), Test Model Development (2014-2016), and Operational Model Development (2017-2019). As a second-phase, we have beta version of KIAPS Integration Model (KIM) that can produce reasonable global forecasting. Using the KIM model, we are evaluating the tropical cyclone forecast in the global model. To objectively provide a best estimate of the storm's central position, we use the Geophysical Fluid Dynamics Laboratory (GFDL) vortex tracker, widely used in tracker algorithms. It gives the track and intensity of the storm throughout the duration of the forecast based on its algorithm. As a verification tool, we use the Model Evaluation Tool - Tropical Cyclone (MET-TC), which produces statistical evaluation. We expect these results give the statue of ability for the tropical cyclone forecast with KIM model.

  3. Human influence on tropical cyclone intensity

    Science.gov (United States)

    Sobel, Adam H.; Camargo, Suzana J.; Hall, Timothy M.; Lee, Chia-Ying; Tippett, Michael K.; Wing, Allison A.

    2016-07-01

    Recent assessments agree that tropical cyclone intensity should increase as the climate warms. Less agreement exists on the detection of recent historical trends in tropical cyclone intensity. We interpret future and recent historical trends by using the theory of potential intensity, which predicts the maximum intensity achievable by a tropical cyclone in a given local environment. Although greenhouse gas-driven warming increases potential intensity, climate model simulations suggest that aerosol cooling has largely canceled that effect over the historical record. Large natural variability complicates analysis of trends, as do poleward shifts in the latitude of maximum intensity. In the absence of strong reductions in greenhouse gas emissions, future greenhouse gas forcing of potential intensity will increasingly dominate over aerosol forcing, leading to substantially larger increases in tropical cyclone intensities.

  4. Cyclone oil shale retorting concept. [Use it all retorting process

    Energy Technology Data Exchange (ETDEWEB)

    Harak, A.E.; Little, W.E.; Faulders, C.R.

    1984-04-01

    A new concept for above-ground retorting of oil shale was disclosed by A.E. Harak in US Patent No. 4,340,463, dated July 20, 1982, and assigned to the US Department of Energy. This patent titled System for Utilizing Oil Shale Fines, describes a process wherein oil shale fines of one-half inch diameter and less are pyrolyzed in an entrained-flow reactor using hot gas from a cyclone combustor. Spent shale and supplemental fuel are burned at slagging conditions in this combustor. Because of fines utilization, the designation Use It All Retorting Process (UIARP) has been adopted. A preliminary process engineering design of the UIARP, analytical tests on six samples of raw oil shale, and a preliminary technical and economic evaluation of the process were performed. The results of these investigations are summarized in this report. The patent description is included. It was concluded that such changes as deleting air preheating in the slag quench and replacing the condenser with a quench-oil scrubber are recognized as being essential. The addition of an entrained flow raw shale preheater ahead of the cyclone retort is probably required, but final acceptance is felt to be contingent on some verification that adequate reaction time cannot be obtained with only the cyclone, or possibly some other twin-cyclone configuration. Sufficient raw shale preheating could probably be done more simply in another manner, perhaps in a screw conveyor shale transporting system. Results of the technical and economic evaluations of Jacobs Engineering indicate that further investigation of the UIARP is definitely worthwhile. The projected capital and operating costs are competitive with costs of other processes as long as electric power generation and sales are part of the processing facility.

  5. Tropical cyclone Pam field survey in Vanuatu

    Science.gov (United States)

    Fritz, Hermann M.; Pilarczyk, Jessica E.; Kosciuch, Thomas; Hong, Isabel; Rarai, Allan; Harrison, Morris J.; Jockley, Fred R.; Horton, Benjamin P.

    2016-04-01

    Severe tropical cyclone Pam (Cat. 5, SSHS) crossed the Vanuatu archipelago with sustained winds of 270 km/h on March 13 and 14, 2015 and made landfall on Erromango. Pam is the most intense tropical cyclone to make landfall on Vanuatu since the advent of satellite imagery based intensity estimates in the 1970s. Pam caused one of the worst natural disaster in Vanuatu's recorded history. Eleven fatalities were directly attributed to cyclone Pam and mostly due to lack of shelter from airborne debris. On March 6 Pam formed east of the Santa Cruz Islands causing coastal inundation on Tuvalu's Vaitupu Island located some 1100 km east of the cyclone center. Pam intensified while tracking southward along Vanuatu severely affecting the Shefa and Tafea Provinces. An international storm surge reconnaissance team was deployed to Vanuatu from June 3 to 17, 2015 to complement earlier local surveys. Cyclone Pam struck a remote island archipelago particularly vulnerable to the combined cyclonic multi-hazards encompassing extreme wind gusts, massive rainfall and coastal flooding due to a combination of storm surge and storm wave impacts. The team surveyed coastal villages on Epi, the Shepherd Islands (Tongoa and Mataso), Efate (including Lelepa), Erromango, and Tanna. The survey spanned 320 km parallel to the cyclone track between Epi and Tanna encompassing more than 45 sites including the hardest hit settlements. Coastal flooding profiles were surveyed from the shoreline to the limit of inundation. Maximum coastal flood elevations and overland flow depths were measured based on water marks on buildings, scars on trees, rafted debris and corroborated with eyewitness accounts. We surveyed 91 high water marks with characteristic coastal flood levels in the 3 to 7 m range and composed of storm surge with superimposed storm waves. Inundation distances were mostly limited to a few hundred meters but reached 800 m on Epi Island. Wrack lines containing pumice perfectly delineated the

  6. The role of large-scale, extratropical dynamics in climate change

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, T.G. [ed.

    1994-02-01

    The climate modeling community has focused recently on improving our understanding of certain processes, such as cloud feedbacks and ocean circulation, that are deemed critical to climate-change prediction. Although attention to such processes is warranted, emphasis on these areas has diminished a general appreciation of the role played by the large-scale dynamics of the extratropical atmosphere. Lack of interest in extratropical dynamics may reflect the assumption that these dynamical processes are a non-problem as far as climate modeling is concerned, since general circulation models (GCMs) calculate motions on this scale from first principles. Nevertheless, serious shortcomings in our ability to understand and simulate large-scale dynamics exist. Partly due to a paucity of standard GCM diagnostic calculations of large-scale motions and their transports of heat, momentum, potential vorticity, and moisture, a comprehensive understanding of the role of large-scale dynamics in GCM climate simulations has not been developed. Uncertainties remain in our understanding and simulation of large-scale extratropical dynamics and their interaction with other climatic processes, such as cloud feedbacks, large-scale ocean circulation, moist convection, air-sea interaction and land-surface processes. To address some of these issues, the 17th Stanstead Seminar was convened at Bishop`s University in Lennoxville, Quebec. The purpose of the Seminar was to promote discussion of the role of large-scale extratropical dynamics in global climate change. Abstracts of the talks are included in this volume. On the basis of these talks, several key issues emerged concerning large-scale extratropical dynamics and their climatic role. Individual records are indexed separately for the database.

  7. Sensitivity experiments on the response of Vb cyclones to sea surface temperature and soil moisture changes

    Science.gov (United States)

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

    2017-07-01

    Extratropical cyclones of type Vb, which develop over the western Mediterranean and move northeastward, are major natural hazards that are responsible for heavy precipitation over central Europe. To gain further understanding in the governing processes of these Vb cyclones, the study explores the role of soil moisture and sea surface temperature (SST) and their contribution to the atmospheric moisture content. Thereby, recent Vb events identified in the ERA-Interim reanalysis are dynamically downscaled with the Weather Research and Forecasting (WRF) model. Results indicate that a mean high-impact summer Vb event is mostly sensitive to an increase in the Mediterranean SSTs and rather insensitive to Atlantic SSTs and soil moisture changes. Hence, an increase of +5 K in Mediterranean SSTs leads to an average increase of 24 % in precipitation over central Europe. This increase in precipitation is mainly induced by larger mean upward moisture flux over the Mediterranean with increasing Mediterranean SSTs. This further invokes an increase in latent energy release, which leads to an increase in atmospheric instability, i.e. in convective available potential energy. Both the increased availability of atmospheric moisture and the increased instability of the atmosphere, which is able to remove extra moisture from the atmosphere due to convective processes, are responsible for the strong increase in precipitation over the entire region influenced by Vb events. Precipitation patterns further indicate that a strong increase in precipitation is found at the eastern coast of the Adriatic Sea for increased Mediterranean SSTs. This premature loss in atmospheric moisture leads to a significant decrease in atmospheric moisture transport to central Europe and the northeastern flanks of the Alpine mountain chain. This leads to a reduction in precipitation in this high-impact region of the Vb event for an increase in Mediterranean SSTs of +5 K. Furthermore, the intensity of the Vb

  8. Observations of cyclone-induced storm surge in coastal Bangladesh

    CERN Document Server

    Chiu, Soyee

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no obvious residual at all. Both maximum and minimum residual water levels are higher for west-landing cyclones producing onshore winds and generally diminish for cyclones making landfall on the Bangladesh coast or eastward producing offshore winds. Water levels observed during cyclones are generally more strongly influenced by tidal phase and amplitude than by storm surge alone. In only 7 of the 15 stations does the highest plausible observed water level coincide with a cyclone. While cyclone-coincident residual water level ...

  9. Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

    Directory of Open Access Journals (Sweden)

    M. Widmann

    2009-09-01

    Full Text Available Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past.

    Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode.

  10. Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

    Directory of Open Access Journals (Sweden)

    M. Widmann

    2010-09-01

    Full Text Available Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past.

    Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode.

  11. The influence of extratropical cloud phase and amount feedbacks on climate sensitivity

    Science.gov (United States)

    Frey, William R.; Kay, Jennifer E.

    2017-07-01

    Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes.

  12. Which way will the circulation shift in a changing climate? Possible nonlinearity of extratropical cloud feedbacks

    Science.gov (United States)

    Tandon, Neil F.; Cane, Mark A.

    2017-06-01

    In a suite of idealized experiments with the Community Atmospheric Model version 3 coupled to a slab ocean, we show that the atmospheric circulation response to CO2 increase is sensitive to extratropical cloud feedback that is potentially nonlinear. Doubling CO2 produces a poleward shift of the Southern Hemisphere (SH) midlatitude jet that is driven primarily by cloud shortwave feedback and modulated by ice albedo feedback, in agreement with earlier studies. More surprisingly, for CO2 increases smaller than 25 %, the SH jet shifts equatorward. Nonlinearities are also apparent in the Northern Hemisphere, but with less zonal symmetry. Baroclinic instability theory and climate feedback analysis suggest that as the CO2 forcing amplitude is reduced, there is a transition from a regime in which cloud and circulation changes are largely decoupled to a regime in which they are highly coupled. In the dynamically coupled regime, there is an apparent cancellation between cloud feedback due to warming and cloud feedback due to the shifting jet, and this allows the ice albedo feedback to dominate in the high latitudes. The extent to which dynamical coupling effects exceed thermodynamic forcing effects is strongly influenced by cloud microphysics: an alternate model configuration with slightly increased cloud liquid (LIQ) produces poleward jet shifts regardless of the amplitude of CO2 forcing. Altering the cloud microphysics also produces substantial spread in the circulation response to CO2 doubling: the LIQ configuration produces a poleward SH jet shift approximately twice that produced under the default configuration. Analysis of large ensembles of the Canadian Earth System Model version 2 demonstrates that nonlinear, cloud-coupled jet shifts are also possible in comprehensive models. We still expect a poleward trend in SH jet latitude for timescales on which CO2 increases by more than 25 %. But on shorter timescales, our results give good reason to expect significant

  13. On the Relationship Between the Length of Season and Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2013

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    Officially, the North Atlantic basin tropical cyclone season runs from June 1 through November 30 of each year. During this 183-day interval, the vast majority of tropical cyclone onsets are found to occur. For example, in a study of the 715 tropical cyclones that occurred in the North Atlantic basin during the interval 1945-2010, it was found that about 97 percent of them had their onsets during the conventional hurricane season, with the bulk (78 percent) having had onset during the late summer-early fall months of August, September, and October and with none having had onset in the month of March. For the 2014 hurricane season, it already has had the onset of its first named storm on July 1 (day of year (DOY) 182), Arthur, which formed off the east coast of Florida, rapidly growing into a category-2 hurricane with peak 1-minute sustained wind speed of about 90 kt and striking the coast of North Carolina as a category-2 hurricane on July 3. Arthur is the first hurricane larger than category-1 to strike the United States (U.S.) since the year 2008 when Ike struck Texas as a category-2 hurricane and there has not been a major hurricane (category-3 or larger) to strike the U.S. since Wilma struck Florida as a category-3 hurricane in 2005. Only two category-1 hurricanes struck the U.S. in the year 2012 (Isaac and Sandy, striking Louisiana and New York, respectively) and there were no U.S. land-falling hurricanes in 2013 (also true for the years 1962, 1973, 1978, 1981, 1982, 1990, 1994, 2000, 2001, 2006, 2009, and 2010). In recent years it has been argued that the length of season (LOS), determined as the inclusive elapsed time between the first storm day (FSD) and the last storm day (LSD) of the yearly hurricane season (i.e., when peak 1-minute sustained wind speed of at least 34 kt occurred and the tropical cyclone was not classified as 'extratropical'), has increased in length with the lengthening believed to be due to the FSD occurring sooner and the LSD occurring

  14. The Genesis of Tropical Cyclone Bilis (2000) Associated with Cross-equatorial Surges

    Institute of Scientific and Technical Information of China (English)

    XU Yamei

    2011-01-01

    The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis (2000) was selected as the case to study. The research data used are from the results of the non-hydrostatic mesoscale model (MM5), which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm. The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end. It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak, sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression, with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation. The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression. The depression was strengthened by cross-equatorial surges, which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

  15. The Genesis of Tropical Cyclone Bilis(2000) Associated with Cross-equatorial Surges

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis(2000) was selected as the case to study.The research data used are from the results of the non-hydrostatic mesoscale model(MM5),which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm.The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end.It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak,sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression,with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation.The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression.The depression was strengthened by cross-equatorial surges,which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

  16. The bi-decadal rainfall cycle, Southern Annular Mode and tropical cyclones over the Limpopo River Basin, southern Africa

    CSIR Research Space (South Africa)

    Malherbe, J

    2014-06-01

    Full Text Available The association between bi-decadal rainfall variability over southern Africa and the rainfall contributed by tropical cyclonic systems from the Southwest Indian Ocean (SWIO) provides a potential means towards understanding decadal-scale variability...

  17. Effect of tropical cyclones on the stratosphere-troposphere exchange observed using satellite observations over the north Indian Ocean

    Science.gov (United States)

    Venkat Ratnam, M.; Babu, S. Ravindra; Das, S. S.; Basha, G.; Krishnamurthy, B. V.; Venkateswararao, B.

    2016-07-01

    Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere-troposphere exchange (STE) processes in the upper troposphere and lower stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007-2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) radio occultation (RO) measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K), and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10-3 kg m-2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10-3 kg m-2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and consequentially the STE in the UTLS region.

  18. Extreme Winter Cyclones in the North Atlantic in a Last Millennium Climate Simulation with CESM1.0.1

    Science.gov (United States)

    Blumer, Sandro R.; Raible, Christoph C.; Lehner, Flavio; Stocker, Thomas F.

    2016-04-01

    Extreme cyclones and their associated impacts are a major threat to mankind, as they often result in heavy precipitation events and severe winds. The last millennium is closest to the Anthropocene and has the best coverage of paleo-climatic information. Therefore, it can serve as a test bed for estimating natural forcing variations beyond the recent observational period and can deliver insight into the frequency and intensity of extreme events, including strong cyclones and their dependency on internal variability and external forcing. The aim of this study is to investigate how the frequency and intensity of extreme cyclones in the North Atlantic have changed in the last millennium, and investigate phases which deviate more than one standard deviation. In particular the changes during prolonged cold and warm periods and the 21st century are analysed to assess the external forcing imprint. We use a comprehensive fully-coupled transient climate simulation of the last millennium (AD 1000-2100) with a relatively high spatial (0.9x1.25 degrees) resolution. Cyclones are then detected and tracked in 12-hourly output using an algorithm that is based on the geopotential height field on 1000 hPa. In addition to the tracking, a Gaussian function is fitted to the depressions in the geopotential height field at every time step in order to have a geometric representation of the low pressure systems. Additionally, two intensity indices for extreme cyclones are defined: the 90 percentile of the mean gradient in geopotential and the 90 percentile of the precipitation within a radius of one standard deviation of the approximated Gaussian function around the cyclone. These criteria consider two aspects of cyclone's intensity: extremes in wind and precipitation. A 30-yr running window is applied to the entire simulation. Within each window the cyclone frequency and the indices for extreme wind and extreme precipitation cyclones are averaged. This analysis reveals decadal to

  19. Characteristics of cyclone climatology and variability in the Southern Ocean

    Institute of Scientific and Technical Information of China (English)

    WEI Lixin; QIN Ting

    2016-01-01

    A new climatology of cyclones in the Southern Ocean is generated by applying an automated cyclone detection and tracking algorithm (developed by Hodges at the Reading University) for an improved and relatively high-resolution European Centre for Medium-Range Weather Forecasts atmospheric reanalysis during 1979–2013. A validation shows that identified cyclone tracks are in good agreement with a available analyzed cyclone product. The climatological characteristics of the Southern Ocean cyclones are then analyzed, including track, number, density, intensity, deepening rate and explosive events. An analysis shows that the number of cyclones in the Southern Ocean has increased for 1979–2013, but only statistically significant in summer. Coincident with the circumpolar trough, a single high-density band of cyclones is observed in 55°–67°S, and cyclone density has generally increased in north of this band for 1979–2013, except summer. The intensity of up to 70% cyclones in the Southern Ocean is less than 980 hPa, and only a few cyclones with pressure less than 920 hPa are detected for 1979–2013. Further analysis shows that a high frequency of explosive cyclones is located in the band of 45°–55°S, and the Atlantic Ocean sector has much higher frequent occurrence of the explosive cyclones than that in the Pacific Ocean sector. Additionally, the relationship between cyclone activities in the Southern Ocean and the Southern Annular Mode is discussed.

  20. Cylinder head covers with integrated, switched cyclone-type oil mist separator; Zylinderkopfhauben mit integriertem geschalteten Zyklon-Oelnebelabscheider

    Energy Technology Data Exchange (ETDEWEB)

    Hintze, S.; Janssen, H.; Karl, W.; Soares, J. [Polytec Automotive GmbH und Co. KG, Lohne (Germany)

    2006-05-15

    Polytec Automotive has developed a new engine ventilation system for integration into cylinder head covers with operating features which distinguish it from all other systems presently on the market. The performance curve for this new switched, patented cyclone separator has been optimized at low flow rates and tuned to reduce the pressure in the high flow range. The wide operating range allows the separating performance of this switched cyclone-type separator to be adjusted to all engines, ensuring universal application. (orig.)

  1. Upper-tropospheric environment-tropical cyclone interactions over the western North Pacific: A statistical study

    Science.gov (United States)

    Qian, Yu-Kun; Liang, Chang-Xia; Yuan, Zhuojian; Peng, Shiqiu; Wu, Junjie; Wang, Sihua

    2016-05-01

    Based on 25-year (1987-2011) tropical cyclone (TC) best track data, a statistical study was carried out to investigate the basic features of upper-tropospheric TC-environment interactions over the western North Pacific. Interaction was defined as the absolute value of eddy momentum flux convergence (EFC) exceeding 10 m s-1 d-1. Based on this definition, it was found that 18% of all six-hourly TC samples experienced interaction. Extreme interaction cases showed that EFC can reach ~120 m s-1 d-1 during the extratropical-cyclone (EC) stage, an order of magnitude larger than reported in previous studies. Composite analysis showed that positive interactions are characterized by a double-jet flow pattern, rather than the traditional trough pattern, because it is the jets that bring in large EFC from the upper-level environment to the TC center. The role of the outflow jet is also enhanced by relatively low inertial stability, as compared to the inflow jet. Among several environmental factors, it was found that extremely large EFC is usually accompanied by high inertial stability, low SST and strong vertical wind shear (VWS). Thus, the positive effect of EFC is cancelled by their negative effects. Only those samples during the EC stage, whose intensities were less dependent on VWS and the underlying SST, could survive in extremely large EFC environments, or even re-intensify. For classical TCs (not in the EC stage), it was found that environments with a moderate EFC value generally below ~25 m s-1 d-1 are more favorable for a TC's intensification than those with extremely large EFC.

  2. tropical cyclone risk analysis: a decisive role of its track

    Science.gov (United States)

    Chelsea Nam, C.; Park, Doo-Sun R.; Ho, Chang-Hoi

    2016-04-01

    The tracks of 85 tropical cyclones (TCs) that made landfall to South Korea for the period 1979-2010 are classified into four clusters by using a fuzzy c-means clustering method. The four clusters are characterized by 1) east-short, 2) east-long, 3) west-long, and 4) west-short based on the moving routes around Korean peninsula. We conducted risk comparison analysis for these four clusters regarding their hazards, exposure, and damages. Here, hazard parameters are calculated from two different sources independently, one from the best-track data (BT) and the other from the 60 weather stations over the country (WS). The results show distinct characteristics of the four clusters in terms of the hazard parameters and economic losses (EL), suggesting that there is a clear track-dependency in the overall TC risk. It is appeared that whether there occurred an "effective collision" overweighs the intensity of the TC per se. The EL ranking did not agree with the BT parameters (maximum wind speed, central pressure, or storm radius), but matches to WS parameter (especially, daily accumulated rainfall and TC-influenced period). The west-approaching TCs (i.e. west-long and west-short clusters) generally recorded larger EL than the east-approaching TCs (i.e. east-short and east-long clusters), although the east-long clusters are the strongest in BT point of view. This can be explained through the spatial distribution of the WS parameters and the regional EL maps corresponding to it. West-approaching TCs accompanied heavy rainfall on the southern regions with the helps of the topographic effect on their tracks, and of the extended stay on the Korean Peninsula in their extratropical transition, that were not allowed to the east-approaching TCs. On the other hand, some regions had EL that are not directly proportional to the hazards, and this is partly attributed to spatial disparity in wealth and vulnerability. Correlation analysis also revealed the importance of rainfall; daily

  3. 飓风“桑迪”温带变性过程特征分析%Characteristics of extratropical transition of hurricane Sandy

    Institute of Scientific and Technical Information of China (English)

    黄蔚薇; 董静舒; 王洁; 许映龙

    2015-01-01

    Based on the 1°×1°NCEP reanalysis data,characteristics of extratropical transition of hurricane Sandy were analyzed.The results indicate that thermal asymmetry of extratropical transition system is displayed directly u-sing thickness fields in low,middle and upper levels of the troposphere,which is favorable to diagnose the extrat-ropical transition of hurricane.Vorticity field could diagnose the coupling of upper-level trough and hurricane,and the extratropical transition begins because the hurricane is impacted by the baroclinic trough after the combination of their positive vorticity.The strong convection during the process of extratropical transition could be enhanced by forced rising of thickness deformation field,lifting of lower frontal zone,positive feedback of condensation and in-creasing upper divergence,which are also reasons of westerly deviation of strong upwarding zone.The warm core of hurricane Sandy falls to the middle and lower levels of the troposphere,which is associated with the sink of strong ascending motion.The warm core can be ruined by strong cold advection,but moderate cold air advection is in favor of Sandy′s redevelopment.Temperature advection distribution at 850 hPa is indicative to Sandy′s track during the extratropical transition process,which approximately parallels the connection between warm and cold ad-vection centers.%利用 NCEP 的1°×1°资料,分析飓风“桑迪”温带变性前后物理量的特征和变化。结果表明:利用对流层低层、中层及高层的厚度场可立体直观地展现热带气旋中心热力结构的对称性,便于进行飓风温带变性的诊断分析。涡度场可诊断高空槽和飓风耦合的情况,两者的正涡度场连接后使热带气旋受到高空槽的影响开始变性。厚度变形场动力强迫上升、低层锋区抬升、强降水区凝结潜热正反馈作用和高空辐散加强等有利于飓风“桑迪”变性过程中深对流的维持及发展

  4. Development of an Extratropical Storm Wind, Wave, and Water Level Climatology for the Offshore Mid-Atlantic

    Science.gov (United States)

    2015-08-01

    ER D C/ CH L TR -1 5- 11 Development of an Extratropical Storm Wind , Wave, and Water Level Climatology for the Offshore Mid-Atlantic...Development of an Extratropical Storm Wind , Wave, and Water Level Climatology for the Offshore Mid-Atlantic Michael F. Forte Field Research Facility...of the extreme offshore wind , wave, and water level climate in the mid-Atlantic region has been conducted for the U.S. Bureau of Safety and

  5. Tropical cyclones in reanalysis data sets

    Science.gov (United States)

    Murakami, Hiroyuki

    2014-03-01

    This study evaluates and compares tropical cyclones (TCs) in state-of-the-art reanalysis data sets including the following: the Japanese 55-year Reanalysis (JRA-55), Japanese 25-year Reanalysis, European Centre for Medium-Range Weather Forecasts Reanalysis-40, Interim Reanalysis, National Centers for Environmental Prediction Climate Forecast System Reanalysis, and NASA's Modern Era Retrospective Analysis for Research and Application (MERRA). Most of the reanalyses reproduce a reasonable global spatial distribution of observed TCs and temporal interannual variation of total TC frequency. Of the six reanalysis data sets, JRA-55 appears to be the best in terms of the following: the highest skill for spatial and temporal distribution of TC frequency of occurrence, highest TC hitting rate, lower false alarm rate, reasonable TC structure in terms of the relationship between maximum surface wind speed and sea level pressure, and higher correlation coefficients for interannual variations of TC frequency. These results also suggest that the finest-resolution reanalysis data sets, like MERRA, are not always the best in terms of TC climatology.

  6. Climate Prediction Center (CPC) Western Pacific Basin Cyclone Monitoring

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tropical cyclones are one of the nature?s destructive phenomena, causing loss of lives and property damage. The affected countries associated with the cyclones of...

  7. NESDIS Microwave Sounder-based Tropical Cyclone (TC) Products

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The S-NPP Microwave Sounder-based Tropical Cyclone (TC) Products provide estimates of tropical cyclone maximum wind speed, minimum sea level pressure, radii of 34,...

  8. Dust cyclone technology for gins – A literature review

    Science.gov (United States)

    Dust cyclone research leading to more efficient designs has helped the cotton ginning industry to comply with increasingly stringent air quality regulations governing fine particulate emissions. Future changes in regulations may require additional improvements in dust cyclone efficacy. This inter-...

  9. Cyclone disaster vulnerability and response experiences in coastal Bangladesh.

    Science.gov (United States)

    Alam, Edris; Collins, Andrew E

    2010-10-01

    For generations, cyclones and tidal surges have frequently devastated lives and property in coastal and island Bangladesh. This study explores vulnerability to cyclone hazards using first-hand coping recollections from prior to, during and after these events. Qualitative field data suggest that, beyond extreme cyclone forces, localised vulnerability is defined in terms of response processes, infrastructure, socially uneven exposure, settlement development patterns, and livelihoods. Prior to cyclones, religious activities increase and people try to save food and valuable possessions. Those in dispersed settlements who fail to reach cyclone shelters take refuge in thatched-roof houses and big-branch trees. However, women and children are affected more despite the modification of traditional hierarchies during cyclone periods. Instinctive survival strategies and intra-community cooperation improve coping post cyclone. This study recommends that disaster reduction programmes encourage cyclone mitigation while being aware of localised realities, endogenous risk analyses, and coping and adaptation of affected communities (as active survivors rather than helpless victims).

  10. Southern Hemisphere strong polar mesoscale cyclones in high-resolution datasets

    Science.gov (United States)

    Pezza, Alexandre; Sadler, Katherine; Uotila, Petteri; Vihma, Timo; Mesquita, Michel D. S.; Reid, Phil

    2016-09-01

    Mesoscale cyclones are small low-pressure systems (usually explosive cyclones" (i.e., rapid intensification but not necessarily short lived). A short climatology (2009-2012) is obtained by using high resolution (0.5°) Antarctic Mesoscale Prediction System (AMPS) mean sea level pressure. The results show a significant improvement of spatial detail compared to the 0.75° resolution ERA-interim dataset, with a total count approximately 46 % higher in AMPS. The subset of mesoscale cyclones that are explosive is small, with a total genesis number of about 13 % that of polar lows. In addition, only about 1 % of the polar lows are explosive, suggesting that cyclones that undergo rapid intensification tend to become larger longer lived (and hence are no longer regarded as polar lows). Mesoscale cyclones are more frequent in winter, with a maximum concentration around the Antarctic but also occurring as far north as Tasmania and New Zealand. Analysis of sensible heat flux and sea ice extent anomalies during the genesis days shows that there is a large spread of genesis points over both positive and negative flux anomalies in winter, with a somewhat random pattern in the other seasons.

  11. Observations of cyclone-induced storm surge in coastal Bangladesh

    OpenAIRE

    Chiu, Soyee; Small, Christopher

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no o...

  12. Temporal clustering of tropical cyclones and its ecosystem impacts

    OpenAIRE

    Peter J Mumby; Vitolo, Renato; Stephenson, David B.

    2011-01-01

    Tropical cyclones have massive economic, social, and ecological impacts, and models of their occurrence influence many planning activities from setting insurance premiums to conservation planning. Most impact models allow for geographically varying cyclone rates but assume that individual storm events occur randomly with constant rate in time. This study analyzes the statistical properties of Atlantic tropical cyclones and shows that local cyclone counts vary in time, with periods of elevated...

  13. Short term teleconnections associated with an individual tropical cyclone

    OpenAIRE

    Woll, Stephen C.

    1993-01-01

    Approved for public release; distribution is unlimited. The short term teleconnections associated with an individual western Pacific tropical cyclone have been investigated using an atmospheric general circulation model. The general strategy was to use the GCM, in combination with several tropical cyclone bogusing procedures, to isolate the effects on the global circulation of the tropical cyclone. The bogusing procedures were used to alter the tropical cyclone in the initial conditions fo...

  14. On the structure of the extra-tropical transition layer from in-situ observations

    OpenAIRE

    Pisso, I.; Law, K. S.; Fierli, F.; P. H. Haynes; P. Hoor; Palazzi, E; F. Ravegnani; S. Viciani

    2012-01-01

    In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994–2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces...

  15. Seasonal Variability of Extratropical North Pacific Wind Stress, Ekman Pumping and Sverdrup Transport

    Science.gov (United States)

    2001-12-01

    The annual cycle of the North Pacific wind stress , Ekman pumping and Sverdrup transport is investigated by means of empirical orthogonal function... stress components. These wind stress components are averaged to 624 monthly mean fields from which monthly mean Ekman pumping and Sverdrup transport...Research (NCAR) Reanalysis daily averaged surface wind components covering the extratropical North Pacific are used to calculate daily averaged wind

  16. A three-dimensional model study on ocean dynamic response to traveling cyclone over the Huanghai Sea

    Institute of Scientific and Technical Information of China (English)

    QIN Zenghao; LI Yongping; YUAN Yaochu; YU Runling

    2005-01-01

    On the basis of numerical simulation of the mean circulation and relevant thermal-salinity fields in June with a three-dimensional ocean model (ECOM-si), the model outputs are used as first guess of initial fields for numerical integration of the model equations and the numerical results are applied to investigating the dynamical responses of the Huanghai Sea and the East China Sea (HECS) in the course of a weak land-to-sea cyclone's passage over the Huanghai Sea on 15~16 June 1999. Predominance of the dynamic impact of cyclone over the thermal one in June in the HECS is justified using observations and model simulations. The cyclone and its surrounding weather system, i.e., subtropical high ridge to its south could influence current and thermal fields in the Bohai Sea, the Huanghai Sea and the northern East China Sea even though the intensity of cyclone was rather weak. The response of oceanic currents to the wind stresses driven by the cyclone and its southern subtropical high were strongly characterized by the wind driit with its extent of equivalent scale of cyclone in the horizontal and of Ekman layer in the vertical. The sea response at a given site was closely related to the transient local wind speed and direction,especially was sensitive to the local wind direction,which is demonstrated at three points locating at the southern and western Huanghai Sea and the northern East China Sea. So the sea responses at locations differed considerably from one another. Current responded to the wind stress in a simple way:directly to the wind-driven current and subsequent gradient current and slope current, etc., whereas sea temperature responded to the wind stress in two ways: directly to the cyclone-induced cooling and indirectly to water movements both in the horizontal and the vertical by the cyclone' s wind stress. So the sea temperature variation under the influence of cyclone was more complicate than the current. The HECS in response to the cyclone and its

  17. Decadal cyclone variability in the North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Luksch, U.; Blender, R.; Fraedrich, K. [Meteorological Inst., Univ. of Hamburg (Germany); Raible, C.C. [Climate and Environmental Physics, Physics Inst., Univ. of Bern (Switzerland)

    2005-12-01

    The unstable midlatitude ocean-atmosphere coupling motivates the definition of two decadal regimes with distinct implications for the North Atlantic cyclone variability. Phases with low (high) decadal variability of the North Atlantic Oscillation, which are connected with an annular (sectoral) spatial scale of the geopotential height teleconnection pattern, are identified as a hemispheric (regional) regime. In the hemispheric regime during a positive El Nino/Southern Oscillation (ENSO) index (warm event), the North Atlantic cyclones and the regions of enhanced precipitation shift southward while over northern Europe the cyclone activity and the rainfall are reduced. During the regional regime this impact of ENSO on the Atlantic storm track is extremely small and a clear interpretation over Europe is inhibited. (orig.)

  18. Cyclone contribution to the Mediterranean Sea water budget

    Science.gov (United States)

    Flaounas, E.; Di Luca, A.; Drobinski, P.; Mailler, S.; Arsouze, T.; Bastin, S.; Beranger, K.; Lebeaupin Brossier, C.

    2016-02-01

    This paper analyzes the impact of cyclones to the atmospheric components on the Mediterranean Sea Water Budget, namely the cyclones contribution to precipitation and evaporation over the Mediterranean Sea. Three regional simulations were performed with the WRF model for the period 1989-2008. The model was run (1) as a standalone model, (2) coupled with the oceanic model NEMO-MED12 and (3) forced by the smoothed Sea Surface Temperature (SST) fields from the second simulation. Cyclones were tracked in all simulations, and their contribution to the total rainfall and evaporation was quantified. Results show that cyclones are mainly associated with extreme precipitation, representing more than 50 % of the annual rainfall over the Mediterranean Sea. On the other hand, we found that cyclone-induced evaporation represents only a small fraction of the annual total, except in winter, when the most intense Mediterranean cyclones take place. Despite the significant contribution of cyclones to rainfall, our results show that there is a balance between cyclone-induced rainfall and evaporation, suggesting a weak net impact of cyclones on the Mediterranean Sea water budget. The sensitivity of our results with respect to rapid SST changes during the development of cyclones was also investigated. Both rainfall and evaporation are affected in correlation with the SST response to the atmosphere. In fact, air feedbacks to the Mediterranean Sea during the cyclones occurrence were shown to cool down the SST and consequently to reduce rainfall and evaporation at the proximity of cyclone centers.

  19. Cyclone IV拓展Altera低成本Cyclone FPGA系列

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ 基于60nm工艺的Cyclone IV FPGA是在现有Cyclone系列FPGA基础上的扩展.cycIone IV FPGA由两个子系列组成,一是Cyclone IV GX FPGA,它是带收发器的低成本、低功耗FPGA且支持业界主流的协议规范;另一款是内核电压1.0的Cyclone IV E FPGA,不含收发器但具有更低成本和功耗.

  20. Upper-level eddy angular momentum fluxes and tropical cyclone intensity change

    Science.gov (United States)

    Demaria, Mark; Baik, Jong-Jin; Kaplan, John

    1993-01-01

    The eddy flux convergence of relative angular momentum (EFC) at 200 mb was calculated for the named tropical cyclones during the 1989-1991 Atlantic hurricane seasons. A period of enhanced EFC within 1500 km of the storm center occurred about every five days due to the interaction with upper-level troughs in the midlatitude westerlies or upper-level, cold lows in low latitudes. Twenty-six of the 32 storms had at least one period of enhanced EFC. In about one-third of the cases, the storm intensified just after the period of enhanced EFC. In most of the cases in which the storm did not intensify the vertical shear increased, the storm moved over cold water, or the storm became extratropical just after the period of enhanced EFC. A statistically significant relationship was found between the EFC within 600 km of the storm center and the intensity change during the next 48 h. The EFC was also examined for the ten storms from the 1989-1991 sample that had the largest intensification rates. Six of the ten periods of rapid intensification were associated with enhanced EFC. In the remaining four cases the storms were intensifying rapidly in a low shear environment without any obvious interaction with upper-level troughs.

  1. On the dynamics of synoptic scale cyclones associated with flood events in Crete

    Science.gov (United States)

    Flocas, Helena; Katavoutas, George; Tsanis, Ioannis; Iordanidou, Vasiliki

    2015-04-01

    Flood events in the Mediterranean are frequently linked to synoptic scale cyclones, although topographical or anthropogenic factors can play important role. The knowledge of the vertical profile and dynamics of these cyclones can serve as a reliable early flood warning system that can further help in hazard mitigation and risk management planning. Crete is the second largest island in the eastern Mediterranean region, being characterized by high precipitation amounts during winter, frequently causing flood events. The objective of this study is to examine the dynamic and thermodynamic mechanisms at the upper and lower levels responsible for the generation of these events, according to their origin domain. The flooding events were recorded for a period of almost 20 years. The surface cyclones are identified with the aid of MS scheme that was appropriately modified and extensively employed in the Mediterranean region in previous studies. Then, the software VTS, specially developed for the Mediterranean cyclones, was employed to investigate the vertical extension, slope and dynamic/kinematic characteristics of the surface cyclones. Composite maps of dynamic/thermodynamic parameters, such as potential vorticity, temperature advection, divergence, surface fluxes were then constructed before and during the time of the flood. The dataset includes 6-hourly surface and isobaric analyses on a 0.5° x 0.5° regular latitude-longitude grid, as derived from the ERA-INTERIM Reanalysis of the ECMWF. It was found that cyclones associated with flood events in Crete mainly generate over northern Africa or southern eastern Mediterranean region and experience their minimum pressure over Crete or southwestern Greece. About 84% of the cyclones extend up to 500hPa, demonstrating that they are well vertically well-organized systems. The vast majority (almost 84%) of the surface cyclones attains their minimum pressure when their 500 hpa counterparts are located in the NW or SW, confirming

  2. Interactions Between Vestige Atlantic Tropical Cyclones and Mid-Latitude Storms Over Mediterranean Basin

    Science.gov (United States)

    Smith, Eric A.; Mehta, Amita; Mugnai, Alberto; Tripoli, Gregory J.

    2007-01-01

    One of the more interesting tropical-mid-latitude interactions is one that has important effects on precipitation within the Mediterranean basin. This interaction consists of an Atlantic tropical cyclone vestige whose original disturbance travels eastward and northward across Atlantic basin, eventually intermingling with a mid-latitude cyclone entering southern Europe and/or the \\bestern Mediterranean Sea. The period for these interactions is from mid-September through November. If the tropical cyclone and its vestige is able to make the eastward Atlantic transit within the low to mid-levels, or if an upper level potential vorticity perturbation Cjet streak) emitted by a Hurricane in its latter stages within the central Atlantic is able to propagate into and along the longwave pattern affecting the western Mediterranean Sea (MED), then there is the prospect for the tropical cyclone remnant to produce a major modification of the mid-latitude storm system preparing to affect the MED region. For such an occurrence to take place, it is necessary for an amplifying baroclinic perturbation to be already situated to the rear of a longwave trough, or to be excited by the emitted jet streak to the rear of a longwave trough -- in either case, preparing to affect the western MED. The Algiers City flood of 9-10 November 2001, which killed some 700 people, was produced by a Mediterranean cyclone that had been influenced by two vestige Atlantic tropical cyclones, 1,orenzo and Noel. A published modeling study involving various of this study's authors has already described the dynamical development of the Algiers storm as it amplified from a developing baroclinic disturbance in the Rossby wave train, into a northern Africa hazardous flood system, then lingered in the western MED as a semi-intense warm core cyclone. In our new modeling experiments, we investigate the impact of what might have happened in the eventual precipitation field. had the main features of the tropical

  3. Analyzing the Response of Climate Perturbations to (Tropical) Cyclones using the WRF Model

    Science.gov (United States)

    Tewari, M.; Mittal, R.; Radhakrishnan, C.; Cipriani, J.; Watson, C.

    2015-12-01

    An analysis of global climate models shows considerable changes in the intensity and characteristics of future, warm climate cyclones. At regional scales, deviations in cyclone characteristics are often derived using idealized perturbations in the humidity, temperature and surface conditions. In this work, a more realistic approach is adopted by applying climate perturbations from the Community Climate System Model (CCSM4) to ERA-interim data to generate the initial and boundary conditions for future climate simulations. The climate signal perturbations are generated from the differences in 21 years of mean data from CCSM4 with representative concentration pathways (RCP8.5) for the periods: (a) 2070-2090 (future climate), (b) 2025-2045 (near-future climate) and (c) 1985-2005 (current climate). Four individual cyclone cases are simulated with and without climate perturbations using the Weather Research and Forecasting model with a nested configuration. Each cyclone is characterized by variations in intensity, landfall location, precipitation and societal damage. To calculate societal damage, we use the recently introduced Cyclone Damage Potential (CDP) index evolved from the Willis Hurricane Index (WHI). As CDP has been developed for general societal applications, this work should provide useful insights for resilience analyses and industry (e.g., re-insurance).

  4. Persistent cyclonic structures in self-similar turbulent flows

    CERN Document Server

    Mininni, P D

    2009-01-01

    Invariance properties of a physical system govern its behavior: energy conservation in turbulence drives a wide distribution of energy among modes, as observed in geophysics, astrophysics and engineering. In hydrodynamic turbulence, the role of helicity (which measures departures from mirror symmetry) remains unclear since it does not alter this distribution. However, the interplay of rotation and helicity leads to significant differences. Using numerical simulations we show the occurence of long-lived laminar cyclonic vortices together with turbulent vortices, reminiscent of recent tornado observations. Furthermore, the small scales are completely self-similar with no deviations from Gaussianity. This result points to the discovery of a small parameter in rotating helical turbulence.

  5. ASPECTS OF CYCLON AND BDNF GENE EXPRESSION IN SCHIZOPHRENIA PATIENTS

    Directory of Open Access Journals (Sweden)

    Rinaldo Shishkov

    2012-08-01

    Full Text Available The pathogenesis of the schizophrenic illness is still not fully elucidated. Many studies have been conducted revealing different aspects but may be the studies of greatest significance are studying the genetic aspects of expression of trophic factors and enzymes associated with nervous system development and plasticity. In this relation we aimed at measuring the Cyclon and BDNF genes expression in blood of patients suffering from schizophrenia and to test for correlation between them. Our result did not reveal correlation in spite of their connection with the disease

  6. Energy transformations associated with the synoptic and planetary scales during the evolution of a blocking anticyclone and an upstream explosively-developing cyclone

    Science.gov (United States)

    Smith, Phillip J.; Tsou, Chih-Hua

    1992-01-01

    The eddy kinetic energy (KE), release of eddy potential energy, generation of eddy kinetic energy, and exchange between eddy and zonal kinetic energy are investigated for a blocking anticyclone over the North Atlantic Ocean and an extratropical cyclone that developed during January 17-21, 1979. The results indicate that KE was maintained by baroclinic conversion of potential to kinetic. As released potential energy was being used to generate KE, a portion of the KE was barotropically converted to zonal KE. These transformations were dominated by the synoptic-scale component. While changes in the mass field depended not only on the synoptic scale but also on the interactions between the synoptic and planetary scales, the corresponding changes in the eddy motion fields responded largely to synoptic-scale processes.

  7. Fujiwhara interaction of tropical cyclone scale vortices using a weighted residual collocation method

    CERN Document Server

    Walsh, Raymond P

    2016-01-01

    The fundamental interaction between tropical cyclones was investigated through a series of water tank experiements by Fujiwhara [20, 21, 22]. However, a complete understanding of tropical cyclones remains an open research challenge although there have been numerous investigations through measurments with aircrafts/satellites, as well as with numerical simulations. This article presents a computational model for simulating the interaction between cyclones. The proposed numerical method is presented briefly, where the time integration is performed by projecting the discrete system onto a Krylov subspace. The method filters the large scale fluid dynamics using a multiresolution approximation, and the unresolved dynamics is modeled with a Smagorinsky type subgrid scale parameterization scheme. Numerical experiments with Fujiwhara interactions are considered to verify modeling accuracy. An excellent agreement between the present simulation and a reference simulation at Re = 5000 has been demonstrated. At Re = 3744...

  8. Extra-tropical origin of equatorial Pacific cold bias in climate models with links to cloud albedo

    Science.gov (United States)

    Burls, Natalie J.; Muir, Leslie; Vincent, Emmanuel M.; Fedorov, Alexey

    2017-09-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in the present study). Here, we investigate the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis suggests that cold SST biases within the extra-tropical Pacific indeed translate into a cold equatorial bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and local surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extra-tropics, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical Pacific albedo and the root-mean-square-error in equatorial SSTs—a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias in the models is to improve the representation of subtropical and mid-latitude cloud albedo.

  9. Extra-tropical origin of equatorial Pacific cold bias in climate models with links to cloud albedo

    Science.gov (United States)

    Burls, Natalie J.; Muir, Leslie; Vincent, Emmanuel M.; Fedorov, Alexey

    2016-11-01

    General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in the present study). Here, we investigate the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis suggests that cold SST biases within the extra-tropical Pacific indeed translate into a cold equatorial bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and local surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extra-tropics, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical Pacific albedo and the root-mean-square-error in equatorial SSTs—a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias in the models is to improve the representation of subtropical and mid-latitude cloud albedo.

  10. Trends Analyses for Several Factors Affected by Tropical Cyclones

    Directory of Open Access Journals (Sweden)

    Md. T. Islam

    2011-01-01

    Full Text Available Problem statement: This study presents an analytical investigation for the trends of several factors such as number of death of peoples, damages of wealth, flood surge heights, wind speed and radius of the severe storm due to tropical cyclones in Bangladesh. Approach: The study is performed by conducting the field visits to cyclone site, collected data and information on damages and deaths of peoples during field visits, necessary data related to tropical cyclones obtained from available publications and news-study. The data since the period of the independence of Bangladesh (nearly 40 years are analyzed. Results: The analyses showed that the 17 major cyclones have been occurred since 1970. Among these 17 major cyclones, the 5 cyclones were tragically severe that killed over 400 thousand peoples. It is observed that the coast of the Bay of Bengal is particularly vulnerable to tropical cyclones. It is revealed that Bangladesh is more vulnerable to devastating cyclones in the recent years because the frequency of the severe cyclones has increased remarkably. Conclusion/Recommendation: The return period of the major cyclones was decreased drastically in recent years and the country, especially, the Bengal Bay is predominantly helpless during the cyclone seasons.

  11. Submesoscale cyclones in the Agulhas Current

    CSIR Research Space (South Africa)

    Krug, Marjolaine

    2017-01-01

    Full Text Available a period of 1 month provide the first high resolution observations of the Agulhas Current’s inshore front. The observations collected in a non-meandering Agulhas Current show the presence of submesoscale cyclonic eddies, generated at the inshore...

  12. Cyclone hazard proneness of districts of India

    Indian Academy of Sciences (India)

    M Mohapatra

    2015-04-01

    Hazards associated with tropical cyclones (TCs) are long-duration rotatory high velocity winds, very heavy rain, and storm tide. India has a coastline of about 7516 km of which 5400 km is along the mainland. The entire coast is affected by cyclones with varying frequency and intensity. Thus classification of TC hazard proneness of the coastal districts is very essential for planning and preparedness aspects of management of TCs. So, an attempt has been made to classify TC hazard proneness of districts by adopting a hazard criteria based on frequency and intensity of cyclone, wind strength, probable maximum precipitation, and probable maximum storm surge. Ninety-six districts including 72 districts touching the coast and 24 districts not touching the coast, but lying within 100 km from the coast have been classified based on their proneness. Out of 96 districts, 12 are very highly prone, 41 are highly prone, 30 are moderately prone, and the remaining 13 districts are less prone. This classification of coastal districts based on hazard may be considered for all the required purposes including coastal zone management and planning. However, the vulnerability of the place has not been taken into consideration. Therefore, composite cyclone risk of a district, which is the product of hazard and vulnerability, needs to be assessed separately through a detailed study.

  13. Initialization, Prediction and Diagnosis of the Rapid Intensification of Tropical Cyclones using the Australian Community Climate and Earth System Simulator, ACCESS

    Science.gov (United States)

    2011-11-23

    diabatic processes act as PV sources and sinks. Furthermore, when the traditional equation is applied to convective systems there can be very large...when friction and diabatic processes are present. The implication of this result is profound, i.e., for most atmospheric systems PV is to a large... diabatic heating and frictional or other forces. J. Atmos. Sci., 44, 828—841. Kepert, J. D. and Y. Wang, 2001: The dynamics of boundary layer jets

  14. Assessment of an ensemble of ocean-atmosphere coupled and uncoupled regional climate models to reproduce the climatology of Mediterranean cyclones

    Science.gov (United States)

    Flaounas, Emmanouil; Kelemen, Fanni Dora; Wernli, Heini; Gaertner, Miguel Angel; Reale, Marco; Sanchez-Gomez, Emilia; Lionello, Piero; Calmanti, Sandro; Podrascanin, Zorica; Somot, Samuel; Akhtar, Naveed; Romera, Raquel; Conte, Dario

    2016-11-01

    This study aims to assess the skill of regional climate models (RCMs) at reproducing the climatology of Mediterranean cyclones. Seven RCMs are considered, five of which were also coupled with an oceanic model. All simulations were forced at the lateral boundaries by the ERA-Interim reanalysis for a common 20-year period (1989-2008). Six different cyclone tracking methods have been applied to all twelve RCM simulations and to the ERA-Interim reanalysis in order to assess the RCMs from the perspective of different cyclone definitions. All RCMs reproduce the main areas of high cyclone occurrence in the region south of the Alps, in the Adriatic, Ionian and Aegean Seas, as well as in the areas close to Cyprus and to Atlas mountains. The RCMs tend to underestimate intense cyclone occurrences over the Mediterranean Sea and reproduce 24-40 % of these systems, as identified in the reanalysis. The use of grid nudging in one of the RCMs is shown to be beneficial, reproducing about 60 % of the intense cyclones and keeping a better track of the seasonal cycle of intense cyclogenesis. Finally, the most intense cyclones tend to be similarly reproduced in coupled and uncoupled model simulations, suggesting that modeling atmosphere-ocean coupled processes has only a weak impact on the climatology and intensity of Mediterranean cyclones.

  15. Climatology of extratropical atmospheric wave packets in the northern hemisphere

    CERN Document Server

    Grazzini, Federico

    2010-01-01

    Planetary and synoptic scale wave-packets represents one important component of the atmospheric large-scale circulation. These dissipative structures are able to rapidly transport eddy kinetic energy, generated locally (e.g. by baroclinic conversion), downstream along the upper tropospheric flow. The transported energy, moving faster than individual weather systems, will affect the development of the next meteorological system on the leading edge of the wave packet, creating a chain of connections between systems that can be far apart in time and space, with important implications on predictability. In this work we present a different and novel approach to investigate atmospheric variability, based on the objective recognition of planetary and synoptic wave packets. We have developed an objective tracking algorithm which allows to extract relevant statistical properties of the wave trains as a function of their dominant wavelength. We have applied the algorithm to the daily analysis (every 12h) from 1958-2009...

  16. Buoyancy in tropical cyclones and other rapidly rotating atmospheric vortices

    Science.gov (United States)

    Smith, Roger K.; Montgomery, Michael T.; Zhu, Hongyan

    2005-07-01

    Motivated primarily by its application to understanding tropical-cyclone intensification and maintenance, we re-examine the concept of buoyancy in rapidly rotating vortices, distinguishing between the buoyancy of the symmetric balanced vortex or system buoyancy, and the local buoyancy associated with cloud dynamics. The conventional definition of buoyancy is contrasted with a generalized form applicable to a vortex, which has a radial as well as a vertical component. If, for the special case of axisymmetric motions, the balanced density and pressure distribution of a rapidly rotating vortex are used as the reference state, the buoyancy field then characterizes the unbalanced density perturbations, i.e. the local buoyancy. We show how to determine such a reference state without approximation. The generation of the toroidal circulation of a vortex, which is necessary for vortex amplification, is characterized in the vorticity equation by the baroclinicity vector. This vector depends, inter-alia, on the horizontal (or radial) gradient of buoyancy evaluated along isobaric surfaces. We show that for a tropical-cyclone-scale vortex, the buoyancy so calculated is significantly different from that calculated at constant height or on surfaces of constant σ ( σ = ( p - p*)/( ps - p*), where p is the actual pressure, p* some reference pressure and ps is the surface pressure). Since many tropical-cyclone models are formulated using σ-coordinates, we examine the calculation of buoyancy on σ-surfaces and derive an expression for the baroclinicity vector in σ-coordinates. The baroclinic forcing term in the azimuthal vorticity equation for an axisymmetric vortex is shown to be approximately equal to the azimuthal component of the curl of the generalized buoyancy. A scale analysis indicates that the vertical gradient of the radial component of generalized buoyancy makes a comparatively small contribution to the generation of toroidal vorticity in a tropical cyclone, but may be

  17. The Representation of Tropical Cyclones Within the Global William Putman Non-Hydrostatic Goddard Earth Observing System Model (GEOS-5) at Cloud-Permitting Resolutions

    Science.gov (United States)

    Putman, William M.

    2010-01-01

    The Goddard Earth Observing System Model (GEOS-S), an earth system model developed in the NASA Global Modeling and Assimilation Office (GMAO), has integrated the non-hydrostatic finite-volume dynamical core on the cubed-sphere grid. The extension to a non-hydrostatic dynamical framework and the quasi-uniform cubed-sphere geometry permits the efficient exploration of global weather and climate modeling at cloud permitting resolutions of 10- to 4-km on today's high performance computing platforms. We have explored a series of incremental increases in global resolution with GEOS-S from irs standard 72-level 27-km resolution (approx.5.5 million cells covering the globe from the surface to 0.1 hPa) down to 3.5-km (approx. 3.6 billion cells).

  18. Characteristics of lightning activity in tropical cyclones developed over North Indian Ocean basin during 2010-2015

    Science.gov (United States)

    Ranalkar, M. R.; Pawar, S. D.; Pradeep Kumar, P.

    2017-05-01

    The characteristics of lightning activity in tropical cyclones (TCs) over North Indian Ocean (NIO) are presented using sample of 21 TCs developed during 2010-2015 using TRMM and World Wide Lightning Location Network (WWLLN) datasets along with information from annual reports of Regional Specialized Meteorological Center (RSMC), New Delhi. The microphysical features such as Polarization Corrected Brightness Temperature (PCT), attenuation corrected reflectivity factor, Ice Water Path (IWP) play a pivotal role in development of convective systems within TCs. The TCs exhibited systematic variation in lightning flashes per day within 300 km of estimated center during their life cycle irrespective of their severity and flash rate within 300 km of storm center. The lightning flashes ranged from 1 to 3500 flashes per day during pre-cyclone stage, 100 to 8000 flashes per day during cyclone stage and 0 to 4300 flashes per day during post-cyclone stage. The TCs produced maximum flash density in eyewall region (20-40 km) and outer rainband region (200-260 km). The WWLLN recorded 165,512 flashes within 300 km of TC centers during their life cycle. The maximum flashes occurred during cyclone stage followed by pre-cyclone and post-cyclone. The time variation of flash rate for all cyclones was episodic and primarily peaked during late night and early morning hours. The diurnal variation of lightning flashes during TCs due to variation in detection efficiency of WWLLN also controls temporal distribution of lightning activity. During rapid intensification, TCs produced profuse lightning flashes per hour. Episodic lightning flashes per hour occurred during weakening stage and prior to landfall. It is evident that outbreaks of lightning flashes prior to maximum intensity change as manifested in maximum sustained wind speed and fall in estimated central pressure (ECP) indicate potential predictive value of lightning activity for TC intensity change.

  19. Fuel for cyclones: The water vapor budget of a hurricane as dependent on its movement

    Science.gov (United States)

    Makarieva, Anastassia M.; Gorshkov, Victor G.; Nefiodov, Andrei V.; Chikunov, Alexander V.; Sheil, Douglas; Nobre, Antonio Donato; Li, Bai-Lian

    2017-09-01

    Despite the dangers associated with tropical cyclones and their rainfall, the origin of the moisture in these storms, which include destructive hurricanes and typhoons, remains surprisingly uncertain. Existing studies have focused on the region 40-400 km from a cyclone's center. It is known that the rainfall within this area cannot be explained by local processes alone but requires imported moisture. Nonetheless, the dynamics of this imported moisture appears unknown. Here, considering a region up to three thousand kilometers from cyclone center, we analyze precipitation, atmospheric moisture and movement velocities for severe tropical cyclones - North Atlantic hurricanes. Our findings indicate that even over such large areas a hurricane's rainfall cannot be accounted for by concurrent evaporation. We propose instead that a hurricane consumes pre-existing atmospheric water vapor as it moves. The propagation velocity of the cyclone, i.e. the difference between its movement velocity and the mean velocity of the surrounding air (steering flow), determines the water vapor budget. Water vapor available to the hurricane through its movement makes the hurricane self-sufficient at about 700 km from the hurricane center obviating the need to concentrate moisture from greater distances. Such hurricanes leave a dry wake, whereby rainfall is suppressed by up to 40% compared to the local long-term mean. The inner radius of this dry footprint approximately coincides with the hurricane's radius of water self-sufficiency. We discuss how Carnot efficiency considerations do not constrain the power of such open systems. Our findings emphasize the incompletely understood role and importance of atmospheric moisture stocks and dynamics in the behavior of severe tropical cyclones.

  20. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity.

    Science.gov (United States)

    Darby, Stephen E; Hackney, Christopher R; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R; Best, James L; Nicholas, Andrew P; Aalto, Rolf

    2016-11-10

    The world's rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being 'drowned' by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world's great deltas. We demonstrate that spatial variations in the Mekong's suspended sediment load are correlated (r = 0.765, P cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world's major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  1. Near-inertial ocean response to tropical cyclone forcing on the Australian North-West Shelf

    Science.gov (United States)

    Rayson, M. D.; Ivey, G. N.; Jones, N. L.; Lowe, R. J.; Wake, G. W.; McConochie, J. D.

    2015-12-01

    The Regional Ocean Modeling System (ROMS) was applied to the Australian North-West Shelf (NWS) to hindcast the ocean response to four intense historical tropical cyclones (TCs). While the four cyclones had very different trajectories across the NWS, all passed within 150 km of a long-term vertical mooring located on the continental shelf in 125 m depth. The observed ocean response at this relatively shallow, Southern Hemisphere shelf site was characterized by the development of a peak in the counter-clockwise (CCW) near-inertial kinetic energy, mixed layer deepening, and subsequent restratification. Strong near-inertial isotherm oscillations were also observed following two of the cyclones. ROMS reproduced these features and also showed that the peak in the near-inertial CCW kinetic energy was observed on the left side of each cyclone trajectory. The time rate of change of near-inertial kinetic energy depended strongly on the storm Rossby number, i.e., defined based on the storm speed, the storm length scale, and the Coriolis frequency. The shallow water depth on the NWS resulted in first, a more rapid decay of near-inertial oscillations than in the deep ocean, and second a generation efficiency (the ratio of near-inertial power to the rate of wind work) of up to 10%, smaller than found for cyclones propagating across deeper water. The total energy put into near-inertial motions is nevertheless large compared to the background tidal energy. The rapid decay of near-inertial motions emphasizes the importance of frictional effects in characterizing the response to cyclone forcing in shallow seas.

  2. Improvements of Satellite-Derived Cyclonic Rainfall over the North Atlantic.

    Science.gov (United States)

    Klepp, Christian-Philipp; Bakan, Stephan; Graßl, Hartmut

    2003-02-01

    Case studies of rainfall, derived from Special Sensor Microwave Imager (SSM/I) satellite data during the passage of individual cyclones over the North Atlantic, are presented to enhance the knowledge of rainfall processes associated with frontal systems. A multisatellite method is applied for complete coverage of the North Atlantic twice a day. Different SSM/I precipitation algorithms have been tested for individual cyclones and compared to the Global Precipitation Climatology Project (GPCP) datasets. An independent rainfall pattern and intensity validation method is presented using voluntary observing ship (VOS) datasets and Advanced Very High Resolution Radiometer (AVHRR) images.Intense cyclones occur frequently in the wintertime period, with cold fronts propagating far south over the North Atlantic. Following upstream, large cloud clusters are frequently embedded in the cellular structured cold air of the backside regions, which produce heavy convective rainfall events, especially in the region off Newfoundland around 50°N. These storms can be easily identified on AVHRR images. It transpired that only the SSM/I rainfall algorithm of Bauer and Schlüssel is sensitive enough to detect the rainfall patterns and intensities observed by VOS for those cyclone types over the North Atlantic. In contrast, the GPCP products do not recognize this backside rainfall, whereas the frontal rainfall conditions are well represented in all tested datasets. This is suggested from the results of an intensive intercomparison study with ship reports from the time period of the Fronts and Atlantic Storm Track Experiment (FASTEX) field campaign. For this purpose, a new technique has been developed to transfer ship report codes into rain-rate estimates. From the analysis of a complete life cycle of a cyclone, it follows that these mesoscale backside rainfall events contribute up to 25% to the total amount of rainfall in North Atlantic cyclones.

  3. THE STRUCTURE OF TROPICAL CYCLONE BY TOVS AND ITS APPLICATION IN NUMERICAL WEATHER PREDICTION

    Institute of Scientific and Technical Information of China (English)

    万齐林; 何溪澄

    2002-01-01

    The TOVS data are used to study the structure of a number of tropical cyclones for the year 2000.Differences are found to some extent between what is found and classic conceptual models in that (1) the horizontal structure is asymmetric and variable so that the low-value centers at low levels of the geopotential hejght field (or the high-value centers at high levels) do not necessarily coincide with the high-value centers of the temperature field; (2) the vertical structure is also variable in the allocation of the anomalies of the geopotential height field between low values at low levels and high values at high levels. It is especially noted that the centers of the anomalies are tilting at both high and low levels or the high level is only at the edge of a high-pressure zone. There is not any significant high-value anomalous center in a corresponding location with the tropical cyclone.The structure of tropical cyclone in the TOVS is also used as reference to modify the structure of typhoon BOGUS in the numerical prediction model system of tropical cyclones. It is found that the modified BOGUS performs better in coordinating with the environment and predicting the track of the tropical cyclone. The demonstration is two-fold - the structure of the typhoon BOGUS is such that it means much in the track prediction and the use of the TOVS-based tropical cyclone structure really helps in improving it. It provides the foundation for modification and evolution of typhoon BOGUS.

  4. DECREASE IN DUST EMISSIONS BY ADDING CYCLONES IN THE CATCHING ASH DEVICE AT NOVOCHERKASSK HYDRO POWER PLANT

    Directory of Open Access Journals (Sweden)

    Korotkova T. G.

    2016-06-01

    Full Text Available After silage of ash captured by the electrostatic precipitator, we installed the cyclone of NIIOGAZ CN-15-500 for exhaust gas pre-treatment of the ash resulting from the process of burning solid fuels (coal of Donetsk in boilers of Novocherkassk hydro power plant. The plant cyclone examination was performed in a production environment of Novocherkassk hydro power station comprising 4 cylindrical cyclone element diameters of 500 mm, and is defined by its real effectiveness, which amounted to 91%. After the cyclone, the gas enters the two-bag filter FRKI-90KP3-2-2 designed to trap solid ash residues and installed over the silo dry ash. Filters are manufactured in climatic design for temperate and cold climate with the accommodation category 4. The article shows the characteristic of the test results and bag filters FRKI- 90K-P3-2-2 before and after the cyclone in the cleaning system. The work presents the analysis of the composition of the ash and compares it with published data. It is experimentally proved that the inclusion of Cyclone CN-15-500 in the process diverting gas purification scheme allowed more efficient operation of fabric filters, reducing the dust significantly for the input gases

  5. High resolution model projections of tropical cyclone landfall over southern Africa under enhanced anthropogenic forcing

    CSIR Research Space (South Africa)

    Malherbe, J

    2011-09-01

    Full Text Available , no such change has been noted when all closed warm-core low pressure systems are considered. Several studies have through the use of coupled global circulation models globally reported a projected decrease in the number of tropical cyclones expected under...

  6. Simulated sensitivity of the tropical climate to extratropical thermal forcing: tropical SSTs and African land surface

    Science.gov (United States)

    Talento, Stefanie; Barreiro, Marcelo

    2016-08-01

    This study investigates the Intertropical Convergence Zone (ITCZ) response to extratropical thermal forcing applied to an atmospheric general circulation model coupled to slab ocean and land models. We focus on the relative roles of the atmosphere, tropical sea surface temperatures (SSTs) and continental surface temperatures in the ITCZ response to the imposed forcing. The forcing consists of cooling in one hemisphere and warming in the other poleward of 40°, with zero global average. Three sets of experiments are performed: in the first the slab ocean and land models are applied globally; in the second the tropical SSTs are kept fixed while the slab land model is applied globally; in the third, in addition, surface temperatures over Africa are kept fixed. Realistic boundary surface conditions are used. We find that the ITCZ shifts towards the warmer hemisphere and that the stronger the forcing, the larger the shift. When the constraint of fixed tropical SST is imposed we find that the ITCZ response is strongly weakened, but it is still not negligible in particular over the Atlantic Ocean and Africa where the precipitation anomalies are of the order of 20 and 60 %, respectively, of the magnitude obtained without the SST restriction. Finally, when the constraint of the African surface temperature is incorporated we find that the ITCZ response completely vanishes, indicating that the ITCZ response to the extratropical forcing is not possible just trough purely atmospheric processes, but needs the involvement of either the tropical SST or the continental surface temperatures. The clear-sky longwave radiation feedback is highlighted as the main physical mechanism operating behind the land-based extratropical to tropical communication.

  7. Tropical Cyclone Interactions Within Central American Gyres

    Science.gov (United States)

    Papin, P. P.; Bosart, L. F.; Torn, R. D.

    2014-12-01

    Central American gyres (CAGs) are broad (~1000 km diameter) low-level cyclonic circulations that organize over Central America during the tropical cyclone (TC) season. While CAGs have rarely been studied, prior work on similar circulations has been conducted on monsoon depressions (MDs) and monsoon gyres (MGs), which possess spatial scales of 1000 - 2500 km in the west Pacific basin. A key difference between MDs and MGs is related to the organization of vorticity around the low-level circulation. MDs possess a symmetrical vorticity pattern where vorticity accumulates near the circulation center over time, occasionally developing into a large TC. In contrast, MGs possess asymmetrical vorticity, organized in mesovorticies, which rotate cyclonically along the periphery of the MG circulation. Small tropical cyclones (TCs) occasionally develop from these mesovorticies. Interaction and development of TCs within CAGs are also common, as noted by a CAG identified during the 2010 PREDICT field project, which involved the interaction of TC Matthew and the development of TC Nicole within the larger CAG. This project is motivated by the lack of prior research on CAGs, as well as the complex scale interactions that occasionally occur between TCs and CAGs. This presentation focuses on the mutual interaction of vortices embedded in the larger-scale cyclonic flow comprising the CAG circulation. Case studies will be presented using a circulation framework to illustrate the relationship between different scale vorticity elements within the CAG. Some of these case studies resemble a MD-like evolution, where a large TC develops through the accumulation of symmetrical vorticity around the CAG (e.g. TC Opal 1995, TC Frances 1998). Other instances resemble a MG-like evolution, where smaller mesovorticies rotate around a common circulation center (e.g. TC Florence 1988). The circulation analysis framework aids in the diagnosis of interaction between different scale cyclonic vortices, and

  8. Toward improving hurricane forecasts using the JPL Tropical Cyclone Information System (TCIS): A framework to address the issues of Big Data

    Science.gov (United States)

    Hristova-Veleva, S. M.; Boothe, M.; Gopalakrishnan, S.; Haddad, Z. S.; Knosp, B.; Lambrigtsen, B.; Li, P.; montgomery, M. T.; Niamsuwan, N.; Tallapragada, V. S.; Tanelli, S.; Turk, J.; Vukicevic, T.

    2013-12-01

    Accurate forecasting of extreme weather requires the use of both regional models as well as global General Circulation Models (GCMs). The regional models have higher resolution and more accurate physics - two critical components needed for properly representing the key convective processes. GCMs, on the other hand, have better depiction of the large-scale environment and, thus, are necessary for properly capturing the important scale interactions. But how to evaluate the models, understand their shortcomings and improve them? Satellite observations can provide invaluable information. And this is where the issues of Big Data come: satellite observations are very complex and have large variety while model forecast are very voluminous. We are developing a system - TCIS - that addresses the issues of model evaluation and process understanding with the goal of improving the accuracy of hurricane forecasts. This NASA/ESTO/AIST-funded project aims at bringing satellite/airborne observations and model forecasts into a common system and developing on-line tools for joint analysis. To properly evaluate the models we go beyond the comparison of the geophysical fields. We input the model fields into instrument simulators (NEOS3, CRTM, etc.) and compute synthetic observations for a more direct comparison to the observed parameters. In this presentation we will start by describing the scientific questions. We will then outline our current framework to provide fusion of models and observations. Next, we will illustrate how the system can be used to evaluate several models (HWRF, GFS, ECMWF) by applying a couple of our analysis tools to several hurricanes observed during the 2013 season. Finally, we will outline our future plans. Our goal is to go beyond the image comparison and point-by-point statistics, by focusing instead on understanding multi-parameter correlations and providing robust statistics. By developing on-line analysis tools, our framework will allow for consistent

  9. Sensitivity of movement and intensity of severe cyclone AILA to the physical processes

    Indian Academy of Sciences (India)

    S Rambabu; D Gayatri Vani; S S V S Ramakrishna; G V Rama; B V AppaRao

    2013-08-01

    Accurate prediction of movement and intensity of tropical cyclone is still most challenging problem in numerical weather prediction. The positive progress in this field can be achieved by providing network of observations in the storm region and best representation of atmospheric physical processes in the model. In the present study later part was attempted to investigate the sensitivity of movement and intensity of the severe cyclonic storm AILA to different physical processes in the Weather Research and Forecasting model. Three sets of experiments were conducted for convection, microphysics (MP) and planetary boundary layer (PBL) processes. Model-simulated fields like minimum central surface pressure, maximum surface wind, track and vector displacement error are considered to test the sensitivity. The results indicate that the movement of the system is more sensitive to the cumulus physics and the intensity of the cyclone is sensitive to both PBL and cumulus physics. The combination of Betts Miller Janjic (BMJ) for convection, Yonsei University (YSU) for PBL and Purdue Lin (LIN) for microphysics is found to perform better than other combination schemes. The horizontal and vertical features of the system along with its special features like complete northward movement of the system throughout the travel period and the consistent cyclonic storm intensity until 15 hrs after the landfall could be well simulated by the model.

  10. An Intercomparison of Semi-Eulerian and Lagrangian Based Cyclone Tracking Methods for the North Pacific and Alaskan Regions

    Science.gov (United States)

    Shippee, N. J.; Atkinson, D. E.

    2014-12-01

    The idea of considering the "end user perspective" regarding storm activity and objective tracking methods used to compile information on their behaviour is particularly important in the Alaskan region. Annually, coastal regions in the North are exposed to stormy conditions, though most impacts occur during periods where multiple storms track over the same area in a short period of time (serial cyclones) or where strong storms occur without the presence of a protective sea ice buffer. From a fixed perspective (i.e. Eulerian), a storm may be identified more by the impacts that it generates at that location (winds, sea state, erosion). From a Lagrangian (tracking) view, the intensity, duration, and characteristics of the synoptic environment may prove more relevant for understanding. The overall "effectiveness" of an objective tracking method depends on the intended use of the provided information. While pitting different methods against each other is not necessarily a fruitful exercise (Mesquita et al. 2009), the reality is that one method may better reflect the reality of storm activity and impacts to those experiencing the weather first hand. One of the more subtle points in extra-tropical cyclone tracking and comparison work is the method by which a storm is defined. Most cyclones are analyzed on MSLP fields; others define a cyclone by relative vorticity (ζ) maxima at 850 hPa (NH) and minima (SH). Storms can also be defined by wind events, or even impacts, at a location. Using counts of strong wind events at a grid point or location can account for pressure gradients both associated with storms and absent of a synoptic event. Three separate tracking algorithms are analyzed to determine the method most likely to produce a long-term homogeneous dataset that can be used to train a statistical seasonal prediction method. These methods include the Serreze algorithm, Hodges TRACK algorithm, and Atkinson algorithm. Both the Serreze and Hodges methods provide a tracking

  11. Probability Distributions for Cyclone Key Parameters and Cyclonic Wind Speed for the East Coast of Indian Region

    Directory of Open Access Journals (Sweden)

    Pradeep K. Goyal

    2011-09-01

    Full Text Available This paper presents a study conducted on the probabilistic distribution of key cyclone parameters and the cyclonic wind speed by analyzing the cyclone track records obtained from India meteorological department for east coast region of India. The dataset of historical landfalling storm tracks in India from 1975–2007 with latitude /longitude and landfall locations are used to map the cyclone tracks in a region of study. The statistical tests were performed to find a best fit distribution to the track data for each cyclone parameter. These parameters include central pressure difference, the radius of maximum wind speed, the translation velocity, track angle with site and are used to generate digital simulated cyclones using wind field simulation techniques. For this, different sets of values for all the cyclone key parameters are generated randomly from their probability distributions. Using these simulated values of the cyclone key parameters, the distribution of wind velocity at a particular site is obtained. The same distribution of wind velocity at the site is also obtained from actual track records and using the distributions of the cyclone key parameters as published in the literature. The simulated distribution is compared with the wind speed distributions obtained from actual track records. The findings are useful in cyclone disaster mitigation.

  12. Assessment of the Effects of Air-Sea-Land Interaction Processes on the Intensity and Impact of Modelled and Observed Coastal Extratropical Cyclones

    Science.gov (United States)

    2011-09-08

    estimated insured value of U.S. coastal properties. June Bengtsson, L. M., K. I. Hodges , M. Esch, N. Keenlyside, L. Kornbleuh, J.-J. Luo, and T...Russell, Makiko~Sato, Drew T. Shindell, Peter H. Stone, Shan Sun, Nick Tausnev, Duane Thresher, Mao-Sung Yao 2005. Present day atmospheric simulations

  13. Submesoscale cyclones in the Agulhas current

    Science.gov (United States)

    Krug, M.; Swart, S.; Gula, J.

    2017-01-01

    Gliders were deployed for the first time in the Agulhas Current region to investigate processes of interactions between western boundary currents and shelf waters. Continuous observations from the gliders in water depths of 100-1000 m and over a period of 1 month provide the first high-resolution observations of the Agulhas Current's inshore front. The observations collected in a nonmeandering Agulhas Current show the presence of submesoscale cyclonic eddies, generated at the inshore boundary of the Agulhas Current. The submesoscale cyclones are often associated with warm water plumes, which extend from their western edge and exhibit strong northeastward currents. These features are a result of shear instabilities and extract their energy from the mean Agulhas Current jet.

  14. Measuring wind and stress under tropical cyclones with scatterometer

    Science.gov (United States)

    Liu, W. Timothy

    2016-07-01

    Ocean surface stress, the turbulent transport of momentum, is largely derived from wind through a drag coefficient. In tropical cyclones (TC), scatterometers have difficulty in measuring strong wind and there is large uncertainty in the drag coefficient. We postulate that the microwave backscatter from ocean surface roughness, which is in equilibrium with local stress, does not distinguish weather systems. The reduced sensitivity of scatterometer wind retrieval algorithm under the strong wind is an air-sea interaction problem that is caused by a change in the behavior of the drag coefficient and not a sensor problem. Under this assumption, we applied a stress retrieval algorithm developed over a moderate wind range to retrieve stress under the strong winds of TCs. Over a moderate wind range, the abundant wind measurements and more established drag coefficient value allow sufficient stress data to be computed from wind to develop a stress retrieval algorithm for the scatterometer. Using unprecedented large amount of stress retrieved from the scatterometer coincident with strong winds in TC, we showed that the drag coefficient decreases with wind speed at a much steeper rate than previously revealed, for wind speeds over 25 m/s. The result implies that the ocean applies less drag to inhibit TC intensification and the TC causes less ocean mixing and surface cooling than previous studies indicated. With continuous and extensive coverage from constellations of scatterometers for several decades, the impact of tropical cyclones on the ocean and the feedback from the ocean are examined.

  15. Particle Residence Time in Column Flotation Based on Cyclonic Separation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-hua; LIU Jiong-tian

    2007-01-01

    The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its unique cyclonic force field. It also has been observed that the presence of a cyclonic force field leads to a lower bottom separation size limit and a reduction of unselective entrainment. The collection zone of the column is considered to consist of two parts, a column separation zone and a cyclonic zone. Total recovery of the collection zone was developed. For our study, we analyzed the particle movement in the cyclonic zone. Particle residence time equations for the cyclonic zone were derived by force analysis. Results obtained in this study provide a theoretical foundation for the design and scale-up of the FCSMC.

  16. A DYNAMICAL INTERPRETATION OF THE WIND FIELD IN TROPICAL CYCLONES

    Institute of Scientific and Technical Information of China (English)

    HAO Shi-feng; CUI Xiao-peng; PAN Jin-song; ZHOU Guan-bo; HU Bo

    2009-01-01

    Based on the primitive equations in polar coordinates and with the supposition that parcel velocity in tropical cyclones is in linear variation and that the distribution of surface pressure agrees with the Fujita formula, a set of equations are derived, which describe the impact of perturbations of central pressure, position of tropical cyclones, direction and velocity of movement of tropical cyclones on the wind field. It is proved that the second order approximation of the kinetic energy of tropical cyclones can be described by the equations under linear approximation. Typhoon Wipha (2007) is selected to verify the above interpretation method, and the results show that the interpretation method of the wind field could give very good results before the landfall of tropical cyclones, while making no apparent improvement after the landfall. The dynamical interpretation method in this paper is applicable to improving the forecasts of the wind field of tropical cyclones close to the coast.

  17. Cyclones, windstorms and the IMILAST project

    Directory of Open Access Journals (Sweden)

    Tim D. Hewson

    2015-09-01

    Full Text Available By way of introduction to the TELLUS thematic cluster on outcomes of the IMILAST project (Intercomparison of MId-LAtitude STorm diagnostics, this paper presents the results of new research that is fundamental for the correct interpretation of IMILAST results. Specifically we investigated the mesoscale structure of cyclonic windstorms, and the representation of those windstorms in re-analysis data. The paper concludes with an overview of the project itself. Twenty-nine historic windstorms are studied in detail, using wide-ranging observational data, and on this basis a conceptual model of the life cycle of a typical windstorm-generating cyclone is developed. The model delineates three wind phenomena, the warm jet, the sting jet and the cold jet, and maps out the typical damage footprint left by each. Focussing on the boundary layer, the physical processes at work in each jet zone are investigated. These include the impact of near-surface stability and exposure on gust strength. Based on numerous cases, a generic description of the sting jet is provided, with many new features highlighted. This phenomenon looks to be unique in that exceptional gusts can be realised well inland because destabilisation is activated from above. We next investigate how well the widely-referenced ERA-Interim re-analysis, that has been a primary data source for IMILAST, can represent windstorms. In many ways, performance is suboptimal. Compared to a benchmark manually-analysed dataset, windstorm-generating cyclones generally do not deepen rapidly enough. In part, this is a resolution limitation. For one medium-sized cyclone, it is shown, using other models, that horizontal resolution of order 20 km or better is required to capture the most damaging winds. In the context of IMILAST, which has used data at resolutions ≥80 km, this is a fundamental result. For this and other reasons, caution is clearly needed when inferring storm behaviour and severity from model

  18. Les cyclones tropicaux et le changement climatique

    Science.gov (United States)

    André, Jean-Claude; Royer, Jean-François; Chauvin, Fabrice

    2008-09-01

    Results from observations and modelling studies, a number of which having been used to support the conclusions of the IPCC fourth assessment report, are presented. For the past and present-day (since 1970) periods, the increase of strong cyclonic activity over the North Atlantic Ocean appears to be in good correlation with increasing temperature of the ocean surface. For regions where observational data are of lesser quality, the increasing trend is less clear. In fact, assessing long-term changes is made difficult due to both the multi-decennial natural variability and the lesser coverage of observations before satellites were made available. Indirect observational data, such as those derived from quantitative estimations of damage caused by tropical cyclones, suffer from many artefacts and do not allow the resolving of the issue either. For the future, only numerical three-dimensional climate models can be used. They nevertheless run presently with too-large grid-sizes, so that their results are still not converging. Various simulations lead indeed to different results, and it is very often difficult to find the physical reasons for these differences. One concludes by indicating some ways through which numerical simulations could be improved, leading to a decrease of uncertainties affecting the prediction of cyclonic activity over the next decades.

  19. Impact of the observed extratropics on climatological simulations of the MJO in a tropical channel model

    Science.gov (United States)

    Hall, Nicholas M. J.; Thibaut, Séverin; Marchesiello, Patrick

    2016-06-01

    A regional model is used to quantify the influence of the extratropics on simulated tropical intraseasonal variability. The Weather Research and Forecasting (WRF) model is run in tropical channel mode with the boundaries at 30° N and S constrained to 6-hourly reanalysis data. Experiments with modified boundary conditions are carried out in which intraseasonal (20-100 days) timescales are removed, or in which only the annual and diurnal cycles are retained. Twin runs are used to give an objective measure of the boundary-independant component of the variance in each case. The model captures MJO-like propagating structures and shows greater zonal-wind variance in runs with full boundary conditions. Comparison between experiments indicates that about half the intraseasonal variance can be attributed to boundary influence, and specifically to the presence of an intraseasonal extratropical signal. This signal is associated with stronger correlations between low-level zonal wind precursors in the Pacific sector and Indian Ocean convective events. Temporal coherence between MJO events in the model and the observations is analysed by defining four phases based on convectively coupled signals in the low-level zonal wind. The model can only match observed events above the level of chance when intraseasonal boundary information is provided. Results are analysed in terms of `primary' and `successive' events. Although the model hindcast skill is generally poor, it is better for successive events.

  20. 基于风雨影响评估的深圳市热带气旋数据库系统%The Tropical Cyclone Database System of Shenzhen Based on the Needs of Typhoon Storm Assessment

    Institute of Scientific and Technical Information of China (English)

    郑群峰; 徐文文; 李磊; 王博

    2014-01-01

    Assessment on the wind and rain hazards during the landfall of tropical cyclone (TC) is an essential task in the weather forecasting and warning service, and the climate data collected during the passage of TC are important to support this job. Taking Shenzhen as an example, a TC climate database system and the technical thoughts used to establish the system are introduced. The system has the following functions: 1) Meteorological data on TCs can be automatically collected and stored into the database; 2) The system can help to pick out historically similar TCs based on the key area checking combined with the TC tracks deviation checking, and consequently help to evaluate the wind and rain hazards of TCs on Shenzhen;3) The system can visually illustrate the impacts of different TCs landing at different cities of Guangdong province; 4) The system can automatically prompt forecasters the hazard level of different TC. Through the platform, forecasters can quickly and efficiently obtain the information on the wind and rain hazards of the TCs with similar paths or landfall points, which will help to evaluate the wind and rain hazards possibly induced by current TC.%风雨影响评估是热带气旋预报预警服务中的一项重要工作,而热带气旋风雨影响的历史气候数据是支撑这一工作的重要依据。以深圳为例,提出了建立热带气旋数据库系统的技术思路,该系统实现了以下几种功能:1)热带气旋数据的后台自动入库;2)关键区和相似离度相结合的相似台风的自动检索和风雨影响分析;3)直观展示广东沿海各市登陆的热带气旋的风雨影响气候概况;4)热带气旋风雨影响等级的自动提示。通过该系统,预报员可以高效、快速地查询历史相似路径或相同登陆点的热带气旋风雨影响情况,从而为分析当前热带气旋可能造成的风雨影响评估提供参考依据。

  1. The contribution of symmetrization to the intensification of Tropical Cyclones

    OpenAIRE

    Miller, Henry A.

    2001-01-01

    Operational ability to forecast tropical cyclone motion is much better than the ability to forecast intensity change. Several recent works have studied the mechanisms that bring about the symmetrization of various types of asymmetries in tropical cyclones. This study was conducted to add to that knowledge by examining the transfers of kinetic energy between scales and how those energy transfers alter the wind structure of the cyclone. Adding to the understanding of how this process can alter ...

  2. Incorporation of Tropical Cyclone Avoidance Into Automated Ship Scheduling

    Science.gov (United States)

    2014-06-01

    TROPICAL CYCLONE AVOIDANCE INTO AUTOMATED SHIP SCHEDULING by Stephen W. Lantz June 2014 Thesis Advisor: Walter DeGrange Co-Advisor: Eva...COVERED Master’s Thesis 4. TITLE AND SUBTITLE INCORPORATION OF TROPICAL CYCLONE AVOIDANCE INTO AUTOMATED SHIP SCHEDULING 5. FUNDING NUMBERS 6... cyclones (TCs) frequently disrupt these plans, requiring diversions and inefficient steaming speeds. We evaluate the impact of adding anticipated TC

  3. Density distribution in a heavy-medium cyclone

    Institute of Scientific and Technical Information of China (English)

    Wang Yuling; Zhao Yuemin; Yang Jianguo

    2011-01-01

    Heavy-medium cyclones are widely used to upgrade run-of-mine coal. But the understanding of flow in a cyclone containing a dense medium is still incomplete. By introducing turbulent diffusion into calculations of centrifugal settling a theoretical distribution function giving the density field can be deduced. Qualitative analysis of the density field in every part of a cylindrical cyclone suggests an optimum design that has exhibited good separation effectiveness and anti-wear performance when in commercial operation.

  4. Cyclone Nargis in Myanmar: lessons for public health preparedness for cyclones.

    Science.gov (United States)

    Guha-Sapir, Debarati; Vogt, Florian

    2009-01-01

    Recent natural disasters such as the 2004 tsunami, 2008 Sichuan earthquake, and the 2008 Myanmar cyclone have killed more than 100,000 people each. Mortality and morbidity associated with natural disasters are a growing concern, especially because extreme climate events are likely to get increasingly frequent. The authors comment on Cyclone Nargis, claiming an extraordinarily high death toll during its devastating track through the Irrawaddy delta in Myanmar on May 2, 2008 and analyze how and why its mortality pattern differs from other typical postdisaster situations. Underlying factors and preconditions are described and the specificity of the Myanmese context is presented. This leads to lessons how excess mortality can be reduced in future high-ranked cyclones, whose recurrence in this region will only be a matter of time.

  5. Extreme Arctic cyclones in CMIP5 historical simulations

    National Research Council Canada - National Science Library

    Vavrus, Stephen J

    2013-01-01

    .... This study addresses whether such powerful storms are an emerging expression of anthropogenic climate change by investigating simulated extreme Arctic cyclones during the historical period (1850–2005...

  6. Detection of cyclonic eddy generated by looping tropical cyclone in the northern South China Sea:a case study

    Institute of Scientific and Technical Information of China (English)

    HU Jianyu; KAWAMURA Hiroshi

    2004-01-01

    A case study on the cyclonic eddy generated by the tropical cyclone looping over the northern South China Sea (NSCS) is presented, using TOPEX/POSEIDON altimeter data and AVHRR sea surface temperature (SST) data.Three cases relating to the tropical cyclone events (Typhoon Kai-Tak in July 2000, Tropical Storm Russ in June 1994 and Tropical Storm Maria in August-September 2000) over the NSCS have been analyzed. For each looping tropical cyclone case, the cyclonic eddy with an obvious sea level depression appears in the sea area where the tropical cyclone takes a loop form, and lasts for about 2 weeks with a slight variation in location. The cold core with the SST difference greater than 2 ℃ against its surrounding areas is also observed by the satellite-derived SST data.

  7. Detection of cyclonic eddy generated by looping tropical cyclone in the northern South China Sea:a case study

    Institute of Scientific and Technical Information of China (English)

    HU Jianyu; KAWAMURA Hiroshi

    2004-01-01

    A case study on the cyclonic eddy generated by the tropical cyclone looping over the northern South China Sea (NSCS) is presented, using TOPEX/POSEIDON altimeter data and AVHRR sea surface temperature (SST) data.Three cases relating to the tropical cyclone events (Typhoon Kai-Tak in July 2000, Tropical Storm Russ in June 1994and Tropical Storm Maria in August-September 2000) over the NSCS have been analyzed. For each looping tropical cyclone case, the cyclonic eddy with an obvious sea level depression appears in the sea area where the tropical cyclone takes a loop form, and lasts for about 2 weeks with a slight variation in location. The cold core with the SST difference greater than 2 ℃ against its surrounding areas is also observed by the satellite-derived SST data.

  8. Quality of cyclone early warning services: a case study in remote off-shore island in Bangladesh

    Science.gov (United States)

    Ashrafi, Z. M.; Mahmud, S.; Mahbub, A. Q. M.

    2015-12-01

    Geographic location, the unique natural setting of the country and its tropical monsoon climate modify and regulate the climatic condition, makes Bangladesh more vulnerable to cyclones and storm surges. Previous studies have showed that 80-90 % of global losses and 53 % of total cyclone-related deaths worldwide, occur in Bangladesh and out of which, 42% of cyclone-caused deaths were recorded in the last two centuries. The Cyclone Preparedness Program (CPP) is a unique joint program under the initiative of Government of Bangladesh and Bangladesh Red Crescent Society that provides a robust cyclone early warning (CEW) system for the 13 coastal districts in Bangladesh. CPP ensures rapid dissemination of official Bangladesh Meteorological Department's CEW signals to these communities. However, inconsistent CEW services are reported in several of these coastal communities. This study offered the quality assessment of CPP CEW services in Nijhum Island, a highly populated remotely located off-shore island in Bangladesh. Primary rural appraisal (household survey, focus group discussion and expert interview) were used for field data collection and Likert scale, for data analysis. Study revealed that cyclone early warning signal dissemination were restricted to small area covering only 35 percent of the total population. Moreover, local inhabitants had very poor understanding about disseminated CEW signals (flag signaling system, signal number & severity) although CPP initiated several training program to build and raise awareness. Consequently, people remained inactive during cyclone and reluctant to seek shelter which resulted in lack of proper post-disaster management. Moreover, local people had concern regarding accuracy of CEW signals disseminated by CPP. To ensure last mile connectivity of CEW services, it is highly recommended that local people should be given more training and awareness on CEW signals and how to respond to the same.

  9. Tropical cyclone statistics in the Northeastern Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Vadillo, E. [Universidad Autonoma de Baja California Sur (UABCS), La Paz, Baja California Sur (Mexico); Zaytsev, O. [Centro Interdisciplinario de Ciencias Marinas, Instituto Politecnico Nacional, La Paz, Baja California Sur (Mexico)]. E-mail: ozaytsev@ipn.mx; Morales-Perez, R. [Instituto Mexicano de Tecnologia del Agua (IMTA), Jiutepec, Morelos (Mexico)

    2007-04-15

    The principal area of tropical cyclogenesis in the tropical eastern Pacific Ocean is offshore in the Gulf of Tehuantepec, between 8 and 15 degrees Celsius N, and most of these cyclones move towards the west and northwest during their initial phase. Historical analysis of tropical cyclone data in the Northeastern (NE) Pacific over the last 38 years (from 1966 to 2004) shows a mean of 16.3 tropical cyclones per year, consisting of 8.8 hurricanes 198 and 7.4 tropical storms. The analysis shows great geographical variability of cyclone tracks, and that there were a considerable number of hurricane strikes along the Mexican coast. About 50% of the tropical cyclones formed turned north to northeast. It was rare that any passed further north than 30 degrees Celsius N in latitude because of the cold California Current. Hurricane tracks that affected the NE Pacific may be separated into 5 groups. We compared the historical record of the sea surface temperature (SST), related with the El Nino events with a data set of tropical cyclones, including frequency, intensity, trajectory, and duration. Although the statistical dependence between the frequencies of tropical cyclones of the most abundant categories, 1 and 2, over this region and SST data was not convincing, the percentage of high intensity hurricanes and hurricanes with a long life-time (greater than 12 days) was more during El Nino years than in non-El Nino years. [Spanish] La principal region de la formacion de ciclones en el oceano Pacifico Este es el Golfo de Tehuantepec, entre los 8 y los 15 grados Celsius N. En su fase inicial los ciclones se mueven hacia el oeste y el noroeste. El analisis historico de los ciclones que se han generado durante los ultimos 38 anos (de 1966 a 2004) muestra un promedio de 16.2 ciclones por ano, consistentes en 8.8 huracanes y 7.4 tormentas tropicales. El analisis muestra una gran variabilidad geografica en la trayectoria de los ciclones, de los cuales un gran numero impacta las

  10. DMS cyclone separation processes for optimization of plastic wastes recycling and their implications.

    Science.gov (United States)

    Gent, Malcolm Richard; Menendez, Mario; Toraño, Javier; Torno, Susana

    2011-06-01

    It is demonstrated that substantial reductions in plastics presently disposed of in landfills can be achieved by cyclone density media separation (DMS). In comparison with the size fraction of plastics presently processed by industrial density separations (generally 6.4 to 9.5 mm), cyclone DMS methods are demonstrated to effectively process a substantially greater range of particle sizes (from 0.5 up to 120 mm). The purities of plastic products and recoveries obtained with a single stage separation using a cylindrical cyclone are shown to attain virtually 100% purity and recoveries >99% for high-density fractions and >98% purity and recoveries were obtained for low-density products. Four alternative schemas of multi-stage separations are presented and analyzed as proposed methods to obtain total low- and high-density plastics fraction recoveries while maintaining near 100% purities. The results of preliminary tests of two of these show that the potential for processing product purities and recoveries >99.98% of both density fractions are indicated. A preliminary economic comparison of capital costs of DMS systems suggests cyclone DMS methods to be comparable with other DMS processes even if the high volume capacity for recycling operations of these is not optimized.

  11. Further theoretical studies of modified cyclone separator as a diesel soot particulate emission arrester.

    Science.gov (United States)

    Mukhopadhyay, N; Bose, P K

    2009-10-01

    Soot particulate emission reduction from diesel engine is one of the most emerging problems associated with the exhaust pollution. Diesel particulate filters (DPF) hold out the prospects of substantially reducing regulated particulate emissions but the question of the reliable regeneration of filters still remains a difficult hurdle to overcome. Many of the solutions proposed to date suffer from design complexity, cost, regeneration problem and energy demands. This study presents a computer aided theoretical analysis for controlling diesel soot particulate emission by cyclone separator--a non contact type particulate removal system considering outer vortex flow, inner vortex flow and packed ceramic fiber filter at the end of vortex finder tube. Cyclone separator with low initial cost, simple construction produces low back pressure and reasonably high collection efficiencies with reduced regeneration problems. Cyclone separator is modified by placing a continuous ceramic packed fiber filter placed at the end of the vortex finder tube. In this work, the grade efficiency model of diesel soot particulate emission is proposed considering outer vortex, inner vortex and the continuous ceramic packed fiber filter. Pressure drop model is also proposed considering the effect of the ceramic fiber filter. Proposed model gives reasonably good collection efficiency with permissible pressure drop limit of diesel engine operation. Theoretical approach is predicted for calculating the cut size diameter considering the effect of Cunningham molecular slip correction factor. The result shows good agreements with existing cyclone and DPF flow characteristics.

  12. The effects of moist entropy and moisture budgets on tropical cyclone development

    Science.gov (United States)

    Juračić, Ana; Raymond, David J.

    2016-08-01

    This paper examines the moist entropy and moisture budgets in tropical cyclones, as well as their relation to tropical cyclone's development. This analysis focuses on the dropsonde data collected during Hurricane and Severe Storm Sentinel project and the accompanying satellite data. Two tropical cyclones of interest are Tropical Storm Gabrielle (2013) and Hurricane Edouard (2014). There were three research flights into Gabrielle (2013), during its nondeveloping and decaying stages. Edouard (2014) was visited four times in different stages of its life cycle, twice during the intensification and twice during the decay. Also, we extended our analysis on the larger data set, consisting of 11 nonintensifying and 12 intensifying systems. Our study shows that the moist entropy tends to increase during intensification and decrease during nonintensifying stages. On the other hand, the moisture budget relates better to the tropical cyclone's current intensity than its development. The sign of the moist entropy tendency depends on the ability of surface fluxes and irreversible moist entropy generation to overcome lateral export of moist entropy and loss due to radiative cooling. Edouard's decay during the last research flight was likely the result of increasing wind shear and low sea surface temperatures. During its decay, Gabrielle had strong column-integrated lateral export of moist entropy and drying between 1 and 4 km height. This is probably the consequence of a dry environment at multiple levels, amplified by a warm and dry anomaly left behind by previous convective activity.

  13. Cyclone trends constrain monsoon variability during Late Oligocene sea level highstands (Kachchh Basin, NW India

    Directory of Open Access Journals (Sweden)

    M. Reuter

    2013-01-01

    Full Text Available Important concerns about the consequences of climate change for India are the potential impact on tropical cyclones and the monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin as an indicator of tropical cyclone activity along the NW Indian coast during the Late Oligocene warming period (~27–24 Ma. Direct proxies providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system in the Early Miocene. The vast shell concentrations comprise a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deep to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished each recording a relative storm wave base depth. (1 A shallow storm wave base is shown by nearshore mollusks, corals and Clypeaster echinoids; (2 an intermediate storm wave base depth is indicated by lepidocyclind foraminifers, Eupatagus echinoids and corallinaceans; and (3 a deep storm wave base is represented by an Amussiopecten–Schizaster echinoid assemblage. Vertical changes in these skeletal associations give evidence of gradually increasing tropical cyclone intensity in line with third-order sea level rise. The intensity of cyclones over the Arabian Sea is primarily linked to the strength of the Indian monsoon. Therefore and since the topographic boundary conditions for the Indian monsoon already existed in the Late Oligocene, the longer-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~26 Ma followed by a period of monsoon weakening during the peak of the Late Oligocene

  14. Numerical forecast and analysis of a tropical-like cyclone in the Ionian Sea

    Directory of Open Access Journals (Sweden)

    S. Davolio

    2009-04-01

    Full Text Available A forecasting system has been implemented for operational weather prediction over southern Italy in the framework of the RISKMED (INTERREG IIIB project, which aims at weather-risk reduction in the central and eastern Mediterranean area. The system comprises two different regional forecasting chains, one based on BOLAM and MOLOCH models, the second based on the Weather Research and Forecasting (WRF model.

    On 26 September 2006, a subsynoptic-scale vortex developed over the Mediterranean Sea and affected south-eastern Italy. The cyclone was documented by radar reflectivity maps, Meteosat Second Generation satellite images and surface stations data. The observational analysis showed that the cyclone possessed the typical characteristics of a Mediterranean tropical-like cyclone.

    All the limited-area models employed in RISKMED were able to properly forecast the formation of the small-scale vortex, although with differences in intensity, trajectory and evolution. The predictability of the event has been evaluated employing a multi-model, multi-analysis approach. The simulation results show strong sensitivity to the specification of the initial and boundary conditions.

    Sensitivity experiments were performed in order to analyse the mechanisms responsible for the development and the maintenance of the cyclone over the sea. The life cycle of the vortex turned out to be characterized by different phases: the orographic cyclogenesis on the lee side of the Atlas Mountains; the initial phase of development, characterised by the critical role played by the surface heat fluxes; the transition to a tropical-like cyclone mainly as a consequence of the latent-heat release associated with strong convective activity over the Ionian Sea; finally, the maintenance of the vortex strength due to both the surface fluxes and the release of latent heat.

  15. The Impact of ENSO on Extratropical Low Frequency Noise in Seasonal Forecasts

    Science.gov (United States)

    Schubert, Siegfried D.; Suarez, Max J.; Chang, Yehui; Branstator, Grant

    2000-01-01

    This study examines the uncertainty in forecasts of the January-February-March (JFM) mean extratropical circulation, and how that uncertainty is modulated by the El Nino/Southern Oscillation (ENSO). The analysis is based on ensembles of hindcasts made with an Atmospheric General Circulation Model (AGCM) forced with sea surface temperatures observed during; the 1983 El Nino and 1989 La Nina events. The AGCM produces pronounced interannual differences in the magnitude of the extratropical seasonal mean noise (intra-ensemble variability). The North Pacific, in particular, shows extensive regions where the 1989 seasonal mean noise kinetic energy (SKE), which is dominated by a "PNA-like" spatial structure, is more than twice that of the 1983 forecasts. The larger SKE in 1989 is associated with a larger than normal barotropic conversion of kinetic energy from the mean Pacific jet to the seasonal mean noise. The generation of SKE due to sub-monthly transients also shows substantial interannual differences, though these are much smaller than the differences in the mean flow conversions. An analysis of the Generation of monthly mean noise kinetic energy (NIKE) and its variability suggests that the seasonal mean noise is predominantly a statistical residue of variability resulting from dynamical processes operating on monthly and shorter times scales. A stochastically-forced barotropic model (linearized about the AGCM's 1983 and 1989 base states) is used to further assess the role of the basic state, submonthly transients, and tropical forcing, in modulating the uncertainties in the seasonal AGCM forecasts. When forced globally with spatially-white noise, the linear model generates much larger variance for the 1989 base state, consistent with the AGCM results. The extratropical variability for the 1989 base state is dominanted by a single eigenmode, and is strongly coupled with forcing over tropical western Pacific and the Indian Ocean, again consistent with the AGCM results

  16. 1995 Annual Tropical Cyclone Report

    Science.gov (United States)

    1995-01-01

    32 ndsec), inclusive . TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) - A dominant climatologi- cal system and a daily upper-level synoptic fea- ture of the...SEOUL CHULALONGKORN UNIVERSITY, BANGKOK CHUNG CHENG INSTITUTE, TAIWAN CITY POLYTECHNIC OF HONG KONG CIUDAD UNIVERSITARIA , MEXICO CIVIL DEFENSE, CHUUK

  17. Economics of oversized cyclones in the cotton ginning industry

    Science.gov (United States)

    Cost of reducing pollution to meet increasingly stringent air quality standards particularly for the U.S. cotton ginning industry is rising overtime. Most industry participants use cyclones to control air pollutants. These cyclones have no moving parts and their initial investment costs are relative...

  18. Waves off Gopalpur, northern Bay of Bengal during cyclone Phailin.

    Digital Repository Service at National Institute of Oceanography (India)

    Amrutha, M.M.; SanilKumar, V.; Anoop, T.R.; Nair, T.M.B.; Nherakkol, A.; Jeyakumar, C

    The wave statistical parameters during Cyclone Phailin which crossed the northern Bay of Bengal are described based on the Directional Waverider buoy-measured wave data from 8 to 13 October 2013. On 12 October 2013, the cyclone passed within 70 km...

  19. Tropical cyclones over NIO during La-Nina Modoki years

    Digital Repository Service at National Institute of Oceanography (India)

    Sumesh, K.G.; RameshKumar, M.R.

    Tropical cyclones over NIO (North Indian Ocean) are highly influenced by the El-Nino and La-Nina activities over the Pacific Ocean Influences of air-sea interaction processes like El-Nino Modoki and La-Nina Modoki on tropical cyclones are less...

  20. Ocean barrier layers' effect on tropical cyclone intensification.

    Science.gov (United States)

    Balaguru, Karthik; Chang, Ping; Saravanan, R; Leung, L Ruby; Xu, Zhao; Li, Mingkui; Hsieh, Jen-Shan

    2012-09-04

    Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.

  1. Could cyclone performance improve with reduced inlet velocity?

    Science.gov (United States)

    Increasingly stringent regulations have resulted in more restrictive air permit requirements at the same time that energy costs have risen. Cyclone operating strategies are sought so cotton gins can control particulate emissions using less energy with current cyclone technology. Tests were conducted...

  2. Novel cyclone empirical pressure drop and emissions with heterogeneous particulate

    Science.gov (United States)

    New cyclone designs equally effective at controlling emissions that have smaller pressure losses would reduce both the financial and the environmental cost of procuring electricity. Tests were conducted with novel and industry standard 30.5 cm diameter cyclones at inlet velocities from 8 to 18 m s-...

  3. Impact of global warming on cyclonic disturbances over south Asian region

    Science.gov (United States)

    Patwardhan, Savita; Kulkarni, Ashwini; Kumar, K. Krishna

    2012-02-01

    A state-of-the-art regional climate modelling system, known as PRECIS (Providing REgional Climates for Impacts Studies) developed by the Hadley Centre for Climate Prediction and Research, UK is applied over the Indian domain to investigate the impact of global warming on the cyclonic disturbances such as depressions and storms. The PRECIS simulations at 50 × 50 km horizontal resolution are made for two time slices, present (1961-1990) and the future (2071-2100), for two socioeconomic scenarios A2 and B2. The model simulations under the scenarios of increasing greenhouse gas concentrations and sulphate aerosols are analysed to study the likely changes in the frequency, intensity and the tracks of cyclonic disturbances forming over north Indian Ocean (Bay of Bengal and Arabian Sea) and the Indian landmass during monsoon season. The model overestimates the frequency of cyclonic disturbances over the Indian subcontinent in baseline simulations (1961-1990). The change is evaluated towards the end of present century (2071-2100) with respect to the baseline climate. The present study indicates that the storm tracks simulated by the model are southwards as compared to the observed tracks during the monsoon season, especially for the two main monsoon months, viz., July and August. The analysis suggests that the frequency of cyclonic disturbances forming over north Indian Ocean is likely to reduce by 9% towards the end of the present century in response to the global warming. However, the intensity of cyclonic disturbances is likely to increase by about 11% compared to the present.

  4. Impact of global warming on cyclonic disturbances over south Asian region

    Indian Academy of Sciences (India)

    Savita Patwardhan; Ashwini Kulkarni; K Krishna Kumar

    2012-02-01

    A state-of-the-art regional climate modelling system, known as PRECIS (Providing REgional Climates for Impacts Studies) developed by the Hadley Centre for Climate Prediction and Research, UK is applied over the Indian domain to investigate the impact of global warming on the cyclonic disturbances such as depressions and storms. The PRECIS simulations at 50 × 50 km horizontal resolution are made for two time slices, present (1961–1990) and the future (2071–2100), for two socioeconomic scenarios A2 and B2. The model simulations under the scenarios of increasing greenhouse gas concentrations and sulphate aerosols are analysed to study the likely changes in the frequency, intensity and the tracks of cyclonic disturbances forming over north Indian Ocean (Bay of Bengal and Arabian Sea) and the Indian landmass during monsoon season. The model overestimates the frequency of cyclonic disturbances over the Indian subcontinent in baseline simulations (1961–1990). The change is evaluated towards the end of present century (2071–2100) with respect to the baseline climate. The present study indicates that the storm tracks simulated by the model are southwards as compared to the observed tracks during the monsoon season, especially for the two main monsoon months, viz., July and August. The analysis suggests that the frequency of cyclonic disturbances forming over north Indian Ocean is likely to reduce by 9% towards the end of the present century in response to the global warming. However, the intensity of cyclonic disturbances is likely to increase by about 11% compared to the present.

  5. Tropical Cyclone Center Positions from Sequences of HDSS Sondes Deployed along High-Altitude Overpasses of Hurricane Joaquin in 2015, during the ONR Tropical Cyclone Intensity field program.

    Science.gov (United States)

    Creasey, R.; Elsberry, R. L.; Hendricks, E. A.

    2016-12-01

    A method is developed to calculate the zero wind center (ZWC) position from a sequence of Yankee High Density Sounding System (HDSS) dropwindsondes deployed during a high-altitude overpass of a tropical cyclone. The approach is similar to the Willoughby and Chelmow technique in that it utilizes the intersections of bearings normal to the wind directions across the center to locate the ZWC position. Average wind directions over 1 km layers are calculated from the highly accurate Global Positioning (GPS) lat./long. positions as the HDSS sonde falls from the 60,000 foot flight-level of the NASA WB57 to the ocean surface. An iterative procedure is used to also account for the storm translation, which is necessary to put these high-frequency HDSS observations into a storm-relative coordinate system. The Tropical Cyclone Intensity (TCI-15) mission into Hurricane Joaquin on 4 October 2015 is examined. The ZWC positions from two center overpasses indicate the vortex tilts from 1 km to 10 km elevation and rotates cyclonically.

  6. Lessons learnt from tropical cyclone losses

    Science.gov (United States)

    Honegger, Caspar; Wüest, Marc; Zimmerli, Peter; Schoeck, Konrad

    2016-04-01

    Swiss Re has a long history in developing natural catastrophe loss models. The tropical cyclone USA and China model are examples for event-based models in their second generation. Both are based on basin-wide probabilistic track sets and calculate explicitly the losses from the sub-perils wind and storm surge in an insurance portfolio. Based on these models, we present two cases studies. China: a view on recent typhoon loss history Over the last 20 years only very few major tropical cyclones have caused severe insurance losses in the Pearl River Delta region and Shanghai, the two main exposure clusters along China's southeast coast. Several storms have made landfall in China every year but most struck areas with relatively low insured values. With this study, we make the point that typhoon landfalls in China have a strong hit-or-miss character and available insured loss experience is too short to form a representative view of risk. Historical storm tracks and a simple loss model applied to a market portfolio - all from publicly available data - are sufficient to illustrate this. An event-based probabilistic model is necessary for a reliable judgement of the typhoon risk in China. New York: current and future tropical cyclone risk In the aftermath of hurricane Sandy 2012, Swiss Re supported the City of New York in identifying ways to significantly improve the resilience to severe weather and climate change. Swiss Re provided a quantitative assessment of potential climate related risks facing the city as well as measures that could reduce those impacts.

  7. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions

    Science.gov (United States)

    Cronin, Meghan F.; Tozuka, Tomoki

    2016-01-01

    In regions of strong sea surface temperature (SST) gradients, the surface “geostrophic” currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic (“thermal wind”) shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed. PMID:27354231

  8. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions.

    Science.gov (United States)

    Cronin, Meghan F; Tozuka, Tomoki

    2016-06-29

    In regions of strong sea surface temperature (SST) gradients, the surface "geostrophic" currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic ("thermal wind") shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed.

  9. Steady State Ocean Response to Wind Forcing in Extratropical Frontal Regions

    Science.gov (United States)

    Cronin, Meghan F.; Tozuka, Tomoki

    2016-06-01

    In regions of strong sea surface temperature (SST) gradients, the surface “geostrophic” currents have a vertical shear aligned with the surface density front defined by the temperature. This surface geostrophic (“thermal wind”) shear can balance a portion of the surface wind stress, altering the classic Ekman response to wind forcing. Here we show that these frontal effects cannot be ignored in the Tropics or in strong frontal regions in the extratropics, such as found in coastal regions and in western boundary currents of all basins. Frontal effects also dominate the classic Ekman response in the regions of both hemispheres where Trade winds change to westerlies. Implications for vertical motion and global heat transport are discussed.

  10. Evaluation, engineering and development of advanced cyclone processes

    Energy Technology Data Exchange (ETDEWEB)

    Durney, T.E.; Cook, A. [Coal Technology Corporation, Bristol, VA (United States); Ferris, D.D. [ICF Kaiser Engineers, Inc., Pittsburgh, PA (United States)] [and others

    1995-11-01

    This research and development project is one of three seeking to develop advanced, cost-effective, coal cleaning processes to help industry comply with 1990 Clean Air Act Regulations. The specific goal for this project is to develop a cycloning technology that will beneficiate coal to a level approaching 85% pyritic sulfur rejection while retaining 85% of the parent coal`s heating value. A clean coal ash content of less than 6% and a moisture content, for both clean coal and reject, of less than 30% are targeted. The process under development is a physical, gravimetric-based cleaning system that removes ash bearing mineral matter and pyritic sulfur. Since a large portion of the Nation`s coal reserves contain significant amounts of pyrite, physical beneficiation is viewed as a potential near-term, cost effective means of producing an environmentally acceptable fuel.

  11. Infectious Diseases and Tropical Cyclones in Southeast China.

    Science.gov (United States)

    Zheng, Jietao; Han, Weixiao; Jiang, Baofa; Ma, Wei; Zhang, Ying

    2017-05-07

    Southeast China is frequently hit by tropical cyclones (TCs) with significant economic and health burdens each year. However, there is a lack of understanding of what infectious diseases could be affected by tropical cyclones. This study aimed to examine the impacts of tropical cyclones on notifiable infectious diseases in southeast China. Disease data between 2005 and 2011 from four coastal provinces in southeast China, including Guangdong, Hainan, Zhejiang, and Fujian province, were collected. Numbers of cases of 14 infectious diseases were compared between risk periods and reference periods for each tropical cyclone. Risk ratios (RRs) were calculated to estimate the risks. TCs were more likely to increase the risk of bacillary dysentery, paratyphoid fever, dengue fever and acute hemorrhagic conjunctivitis (ps cyclones.

  12. Modified diffusion with memory for cyclone track fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Bernido, Christopher C., E-mail: cbernido@mozcom.com [Research Center for Theoretical Physics, Central Visayan Institute Foundation, Jagna, Bohol 6308 (Philippines); Carpio-Bernido, M. Victoria [Research Center for Theoretical Physics, Central Visayan Institute Foundation, Jagna, Bohol 6308 (Philippines); Escobido, Matthew G.O. [W. Sycip Graduate School of Business, Asian Institute of Management, 123 Paseo de Roxas Ave., Makati City 1260 (Philippines)

    2014-06-13

    Fluctuations in a time series for tropical cyclone tracks are investigated based on an exponentially modified Brownian motion. The mean square displacement (MSD) is evaluated and compared to a recent work on cyclone tracks based on fractional Brownian motion (fBm). Unlike the work based on fBm, the present approach is found to capture the behavior of MSD versus time graphs for cyclones even for large values of time. - Highlights: • Cyclone track fluctuations are modeled as stochastic processes with memory. • Stochastic memory functions beyond fractional Brownian motion are introduced. • The model captures the behavior of cyclone track fluctuations for longer periods of time. • The approach can model time series for other fluctuating phenomena.

  13. On the Effect of Extratropical Wind Stress Forcing on Pacific Subtropical Cells and Tropical Climate

    Science.gov (United States)

    Graffino, Giorgio; Farneti, Riccardo; Kucharski, Fred

    2017-04-01

    The influence of extratropical atmospheric dynamics on the tropical ocean state is a classical example of ocean-atmosphere teleconnection. One way to influence tropical climate is through oceanic SubTropical Cells (STCs), shallow overturning circulation structures connecting the Equatorial Ocean with the subtropical regions. STC are responsible for large mass and energy transports, and their influence on tropical climate, and consequently on the global climate, is fundamental both on the mean and its variability. These circulation structures are present in all basins across the Tropics (Pacific, Atlantic, and Indian Ocean), with different properties and strengths due to the features of each basin. We focus here on the effect of off-equatorial winds on the Pacific STCs, which are the largest and have been previously studied for their potential role in driving low-frequency Pacific variability. Using the Modular Ocean Model version 5 (MOM5), we force the ocean surface with idealized wind stress and wind stress curl anomaly patterns, in order to highlight the influence of subtropical and extratropical forcing on STCs dynamics, and, eventually, on some aspects of Pacific tropical climate. Results have been compared with a control simulation, in which a climatological forcing has been applied at the ocean surface. Our simulations show an increased (reduced) meridional water transport for positive (negative) wind stress anomalies in the Subtropics; the structure of the thermocline at the Equator is modified as well, where cold (warm) anomalies appear. Those signatures result from anomalous values of Equatorial UnderCurrent (EUC), which is partly fed by the STCs. Meridional ocean heat transport is influenced too, showing larger (weaker) values for stronger (weaker) subtropical wind stress. Anomalous circulations are further analyzed for the interior and western boundary transports, and scalings are derived linking subtropical wind stress, STC transports and tropical

  14. Extratropical influences on the inter-annual variability of South-Asian monsoon

    Science.gov (United States)

    Syed, F. S.; Yoo, J. H.; Körnich, H.; Kucharski, F.

    2012-04-01

    The effects of extratropical dynamics on the interannual variations in South-Asian Monsoon (SAM) are examined. Based on NCEP/NCAR reanalysis and CRU precipitation data, a conditional maximum covariance analysis is performed on sea level pressure, 200 hPa geopotential heights and the SAM rainfall by removing the linear effects of El-Niño Southern Oscillation from the fields. It is found that two modes provide a strong connection between the upper-level circulation in the Atlantic/European region and SAM rainfall: the Circumglobal Teleconnection (CGT) and the Summer North Atlantic Oscillation (SNAO). The structures in the 200 hPa heights of both modes in the Atlantic region are similar in the Atlantic region, and their southeastward extension to South Asia (SA) also corresponds to upper-level ridges (in their positive phases) in slightly different positions. Nevertheless, the influence of both modes on SAM rainfall is distinct. Whereas a positive CGT is related to a widespread increase of rainfall in SAM, a positive SNAO is related to a precipitation dipole with its positive phase over Pakistan and the negative phase over northern India. The physical mechanisms for the influence of CGT and SNAO on SAM are related to the upper-level geopotential anomaly which affects the amplitude and position of the low-level convergence. The small displacements of the centers of these responses and the low level cold advection from the north east of SA in case of SNAO explain the differences in the corresponding SAM rainfall distributions. These findings are confirmed with the relatively high-resolution coupled climate model EC-Earth, which gives confidence in the physical basis and robustness of these extratropical variability modes and their influence on the South-Asian monsoon rainfall.

  15. Clouds and the extratropical circulation response to global warming in a hierarchy of global atmosphere models

    Science.gov (United States)

    Voigt, Aiko

    2017-04-01

    Climate models project that global warming will lead to substantial changes in the position of the extratropical jet streams. Yet, many quantitative aspects of such jet stream changes remain uncertain among models, and recent work has indicated a potentially important role of cloud radiative interactions. Here, I will investigate how cloud-radiative changes impact the extratropical circulation response using a hierarchy of global atmosphere models. I will first focus on aquaplanet setups with prescribed sea-surface temperatures (SSTs), which reproduce the model spread found in realistic simulations with interactive SSTs. Simulations with two CMIP5 models MPI-ESM and IPSL-CM5A and prescribed clouds show that half of the circulation response can be attributed to cloud changes. The rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry Held-Suarez model, although the latter is too sensitive because of its simplified treatment of diabatic processes. I will then show that the aquaplanet results also hold when the models are used in a realistic setup that includes continents and seasonality. Finally, I will juxtapose these prescribed-SST simulations with interactive-SST simulations. This will allow for a comparison of the circulation impacts of atmospheric and surface cloud-radiative changes.

  16. Analysis of Tropical Cyclone Tracks in the North Indian Ocean

    Science.gov (United States)

    Patwardhan, A.; Paliwal, M.; Mohapatra, M.

    2011-12-01

    Cyclones are regarded as one of the most dangerous meteorological phenomena of the tropical region. The probability of landfall of a tropical cyclone depends on its movement (trajectory). Analysis of trajectories of tropical cyclones could be useful for identifying potentially predictable characteristics. There is long history of analysis of tropical cyclones tracks. A common approach is using different clustering techniques to group the cyclone tracks on the basis of certain characteristics. Various clustering method have been used to study the tropical cyclones in different ocean basins like western North Pacific ocean (Elsner and Liu, 2003; Camargo et al., 2007), North Atlantic Ocean (Elsner, 2003; Gaffney et al. 2007; Nakamura et al., 2009). In this study, tropical cyclone tracks in the North Indian Ocean basin, for the period 1961-2010 have been analyzed and grouped into clusters based on their spatial characteristics. A tropical cyclone trajectory is approximated as an open curve and described by its first two moments. The resulting clusters have different centroid locations and also differently shaped variance ellipses. These track characteristics are then used in the standard clustering algorithms which allow the whole track shape, length, and location to be incorporated into the clustering methodology. The resulting clusters have different genesis locations and trajectory shapes. We have also examined characteristics such as life span, maximum sustained wind speed, landfall, seasonality, many of which are significantly different across the identified clusters. The clustering approach groups cyclones with higher maximum wind speed and longest life span in to one cluster. Another cluster includes short duration cyclonic events that are mostly deep depressions and significant for rainfall over Eastern and Central India. The clustering approach is likely to prove useful for analysis of events of significance with regard to impacts.

  17. Impact of Megha-Tropiques SAPHIR radiance assimilation on the simulation of tropical cyclones over Bay of Bengal

    Science.gov (United States)

    Dhanya, M.; Gopalakrishnan, Deepak; Chandrasekar, Anantharaman; Singh, Sanjeev Kumar; Prasad, V. S.

    2016-05-01

    Impact of SAPHIR radiance assimilation on the simulation of tropical cyclones over Indian region has been investigated using the Weather Research and Forecasting (WRF) model. Three cyclones that formed over Bay of Bengal have been considered in the present study. Assimilation methodology used here is the three dimensional variational (3DVar) scheme within the WRF model. With the initial and boundary conditions from Global Forecasting System (GFS) analyses from the National Centres for Environmental Prediction (NCEP), a control run (CTRL) without assimilation of any data and a 3DVar run with the assimilation of SAPHIR radiance have been performed. Both model simulations have been compared with the observations from India Meteorological Department (IMD), Tropical Rainfall Measurement Mission (TRMM), and analysis fields from GFS. Detailed analysis reveals that, the SAPHIR radiance assimilation has led to significant improvement in the simulation of all the three cyclones in terms of cyclone track, intensity, accumulated rainfall. The simulation of warm core structure and relative vorticity profile of each cyclone by 3DVar run are found to be more closer to GFS analyses, when compared with the CTRL run.

  18. Numerical simulation of gas-solids two-phase flow field of built-in fourth stage cyclone separation system in FCCU%FCC内置式四旋分离系统内气固两相流场的数值研究

    Institute of Scientific and Technical Information of China (English)

    王锐; 王建军; 赵艳; 金有海

    2014-01-01

    通过数值模拟的方法,采用RSM湍流模型对FCC内置式四旋分离系统内气固两相流场进行了研究。研究表明,四旋灰斗底部存在错流,不利于排料;储料罐顶部平衡管泄气有利于四旋排料,但同时增加了颗粒逃逸的概率,降低分离系统效率;分离系统内颗粒运动轨迹包括灰斗捕集、排气管逃逸及平衡管逃逸,控制颗粒在平衡管逃逸可通过在储料罐内添加锥形挡板结构实现;四旋环形空间顶部与灰斗底部锥段颗粒浓度较高,易对四旋内壁产生磨损;内置式四旋分离系统优点在于不存在催化剂跑损问题。%The Reynolds stress model was used to simulate gas-solids flow field of built-in fourth stage separation cyclone system in FCCU. Cross flow existed at the bottom of the dust hopper in the cyclone separator, which was not favorable for particle discharge. Although blowdown on the top of the dust storage tank could help separator discharge, it also increased the chance of particles escaping from the balance tube, lowering separation efficiency. The movement trajectory of particles in the system included trapped in the dust hopper of the dust storage tank, escaping from the vortex finder and the balance tube. In order to reduce particles escaping from the balance tube, adding a cone baffle in the dust storage tank could be an effective way. Particle concentration was higher at the top of the annular space and the bottom of the dust hopper, causing wall wear out. The built-in fourth stage separation cyclone system had an advantage of resolving catalyst loss.

  19. Role of scale interactions in the abrupt change of tropical cyclone in autumn over the Western North Pacific

    Science.gov (United States)

    Hsu, Pang-Chi; Lee, Ting-Hui; Tsou, Chih-Hua; Chu, Pao-Shin; Qian, Yitian; Bi, Mingyu

    2017-01-01

    Tropical cyclone (TC) activity in autumn (September-November) over the western North Pacific experienced an abrupt change in 1998, which can be detected by the Bayesian change-point analysis. During the decade before the regime shift (1988-1997), the occurrence frequency of TC genesis increased significantly over the tropical western Pacific, where the seasonal cyclonic flow, intraseasonal oscillation (ISO) and synoptic-scale eddy (SSE) were all strengthened, compared to those observed in the decade after 1998 (1998-2007). The TC trajectories also exhibited spatial differences. During the active decade, the TCs had a higher probability to move westward into the Philippine Sea and the South China Sea, and recurved northeastward toward the east of Japan. Meanwhile, the northwestward propagating TCs approaching Taiwan and southeastern coast of China were reduced. To understand the role of mean flow-ISO-SSE interaction in the decadal changes of SSE and associated TC activity, we diagnosed a newly proposed SSE kinetic energy (KE) equation that separates the contributions of seasonal-mean circulation and ISO to the SSE. The results show that, during the active TC decade, the SSE obtained higher KE from both mean flow and ISO through eddy barotropic energy conversion when the enhanced SSE momentum flux interacted with the strengthened monsoon trough and vigorous ISO cyclonic anomaly over the western tropical Pacific. The increased SSE KE contributed positively to the increased TC genesis over the main genesis region (7.5°-20°N, 130°-170°E). It also benefited the growth of TCs over the Philippine Sea and the South China Sea during the active decade. The decadal change in TC frequency over the extratropics was related to the eddy baroclinic energy conversion instead of the barotropic conversion associated with scale interaction. During the active TC decade, SSE gained more (less) KE from the SSE available potential energy over the east of Japan (the East China Sea

  20. A comparative study of chlorophyll-a concentration during different tropical cyclones in the Bay of Bengal based on measurements and model simulations

    Science.gov (United States)

    Pandey, Suchita; Bhagawati, Chirantan; Patel, Ramkrushnbhai; Chakraborty, Arun; Jayanarayanan, Kuttippurath

    2016-04-01

    Chlorophyll-a (chl-a) pigments derived from ocean color can be used as a tool for estimating phytoplankton distribution in the observed oceanic region. This study aims at providing new insights on the variability of chl-a concentration during the occurrences of different cyclones in the Bay of Bengal (BoB). We consider two tropical cyclones of different intensities observed in the BOB; MALA and NILAM. MALA was a cyclonic storm and was formed on 24 April 2006 and dissipated by 30 April 2006. The wind speed and lowest pressure during the MALA have been recorded as 185‒220 Km/h and 950 hp, respectively. Multi-satellite observations are used for chl-a (SeaWiFS, MODIS, OCM-2), winds (QuickSCAT) and sea surface height (SSH) (TOPEX/POSEIDON) analyses in this study. Argo data taken from CORIOLIS (along the cyclone track) are used for temperature and salinity, from which Mixed Layer Depth (MLD), Isothermal Layer Depth (ILD), Barrier Layer Thickness (BLT) is calculated. A case study for MALA cyclone using daily forcing of winds and surface net heat flux in 'Regional Ocean Modeling System' (ROMS) with NPCHLZD (Nitrate, Phytoplankton, Chlorophyll, Zooplankton and Detritus), five components ecosystem model is used for study the chl-a variability during the cyclone. The results show high chl-a concentration along the track as well as in the right side of the track of the cyclone. The daily variations of MLD, BLT, SSH and wind stress curl (WSC) are compared with the daily time series of chl-a for pre-cyclone, during cyclone and post cyclone period. During and after the passage of cyclone average chl-a values increased from 0.2 mg/l to 0.4 mg/l and greater. It shows good agreement with MLD (30‒40 m), negligible BLT and strong WSC (4*10-6n/m3). It implies the strong winds has initiated upwelling, which subsequently triggered phytoplankton bloom during and after the cyclonic storm. The cyclone NILAM was formed on 28 October 2012 and dissipated by 1 November 2012, which had a

  1. A New Calculation Method of the Axial and Radial Velocity and Grade—Efficiency for High—Efficiency Cyclones

    Institute of Scientific and Technical Information of China (English)

    ZhangCOngzhi; WangZijie

    1995-01-01

    At present in China,the cyclones are widely used in the dust removal ventilation system of boilers,industry funaces of pits etc.,because of their simple structure,long life and cost efficiency,In order to improve efficiency of the cyclones,new theoretical calculation method is very important.In this paper,the concept of down-flow quantity is introduced and new formula is decuted based on Kilven law and the work has done by Zhao Weizhong[1],The formula is not only of advantage theoretically but also fit with experimental results quite well.On the basis,the effect of three-dimensional velocity distribution in the flow field within cyclones and other parameters on the grade-efficiency calcuation are analyzed and a new equation for grade-efficiency estimation is introduced.The calculating accuracy of the equation is better than the others theoretically and experimentally.

  2. Temporal clustering of tropical cyclones and its ecosystem impacts.

    Science.gov (United States)

    Mumby, Peter J; Vitolo, Renato; Stephenson, David B

    2011-10-25

    Tropical cyclones have massive economic, social, and ecological impacts, and models of their occurrence influence many planning activities from setting insurance premiums to conservation planning. Most impact models allow for geographically varying cyclone rates but assume that individual storm events occur randomly with constant rate in time. This study analyzes the statistical properties of Atlantic tropical cyclones and shows that local cyclone counts vary in time, with periods of elevated activity followed by relative quiescence. Such temporal clustering is particularly strong in the Caribbean Sea, along the coasts of Belize, Honduras, Costa Rica, Jamaica, the southwest of Haiti, and in the main hurricane development region in the North Atlantic between Africa and the Caribbean. Failing to recognize this natural nonstationarity in cyclone rates can give inaccurate impact predictions. We demonstrate this by exploring cyclone impacts on coral reefs. For a given cyclone rate, we find that clustered events have a less detrimental impact than independent random events. Predictions using a standard random hurricane model were overly pessimistic, predicting reef degradation more than a decade earlier than that expected under clustered disturbance. The presence of clustering allows coral reefs more time to recover to healthier states, but the impacts of clustering will vary from one ecosystem to another.

  3. Boundary-Layer Wind Structure in a Landfalling Tropical Cyclone

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this study, a slab boundary layer model with a constant depth is used to analyze the boundary-layer wind structure in a landfalling tropical cyclone. Asymmetry is found in both the tangential and radial components of horizontal wind in the tropical cyclone boundary layer at landfall. For a steady tropical cyclone on a straight coastline at landfall, the magnitude of the radial component is greater in the offshoreflow side and the tangential component is greater over the sea, slightly offshore, therefore the greater total wind speed occurs in the offshore-flow side over the sea. The budget analysis suggests that: (1) a greater surface friction over land produces a greater inflow and the nonlinear effect advects the maximum inflow downstream, and (2) a smaller surface friction over the sea makes the decrease of the tangential wind component less than that over land. Moreover, the boundary layer wind structures in a tropical cyclone are related to the locations of the tropical cyclone relative to the coastline due to the different surface frictions. During tropical cyclone landfall, the impact of rough terrain on the cyclone increases, so the magnitude of the radial component of wind speed increases in the offshore-flow side and the tangential component outside the radius of maximum wind speed decreases gradually.

  4. Mathematical Model of the Multi-Channel Spiral Cyclone

    Directory of Open Access Journals (Sweden)

    Justina Danilenkaitė

    2013-12-01

    Full Text Available The article deals with a problem of experimental investigation and numerical simulation of gas aerodynamics of a multi-channel spiral cyclone with a tangential inlet. The paper presents an overview of experimental and theoretical works on the cyclones having a particularly complex turbulent flow and focuses on three-dimensional transport differential equations for a non-compressible laminar and turbulent flow inside the cyclone. The equations have been solved applying the numerical finite volume method using the RNG (Re–Normalisation Group k-ε turbulence model. The numerical simulation of the flow cyclone has been carried out. The height of the cyclone is 0.80 m with 0.33 m in diameter, the height of the spiral–cylindrical part – 0.098 meters and that of the cone – 0.45 m. Inlet dimensions (cylindrical part on the side, in accordance with drawings makes a×b = 28×95 mm. The mathematical model for the air traffic movement cyclone has accounted for Navier-Stokes (Reynolds three-dimensional differential equations. The simulation results have been obtained with reference to the cyclone of tangential velocity profiles using RNG k-ε turbulence model. The inlet velocity of 5.1 m/s slightly differs from experimental results, thus making an error of 7%.Article in Lithuanian

  5. Damaging sediment density flows triggered by tropical cyclones

    Science.gov (United States)

    Pope, Ed L.; Talling, Peter J.; Carter, Lionel; Clare, Michael A.; Hunt, James E.

    2017-01-01

    The global network of subsea fibre-optic cables plays a critical role in the world economy and is considered as strategic infrastructure for many nations. Sediment density flows have caused significant disruption to this network in the recent past. These cable breaks represent the only means to actively monitor such flows over large oceanic regions. Here, we use a global cable break database to analyse tropical cyclone triggering of sediment density flows worldwide over 25 yrs. Cable breaking sediment density flows are triggered in nearly all areas exposed to tropical cyclones but most occur in the NW Pacific. They are triggered by one of three sets of mechanisms. Tropical cyclones directly trigger flows, synchronous to their passage, as a consequence of storm waves, currents and surges. Cyclones also trigger flows indirectly, with near-synchronous timing to their passage, as a consequence of peak flood discharges. Last, cyclones trigger flows after a delay of days as a consequence of the failure of large volumes of rapidly deposited sediment. No clear relationship emerges between tropical cyclone activity (i.e. track, frequency and intensity) and the number of sediment density flows triggered. This is a consequence of the short period of observation. However, expansion of the cable network and predicted changes to cyclone activity in specific regions increases the likelihood of increasing numbers of damaging flows.

  6. Experimental research on cyclone performance at high temperature

    Institute of Scientific and Technical Information of China (English)

    LI Wenqi; CHEN Jianyi

    2007-01-01

    To predict the influence of operating temperatures on cyclone performance,an experimental investigation was conducted on particle separation in a reverse flow,tangential volute-inlet cyclone separator with a diameter of 300 mm and with air heated up to 973 K.The test powder silica has a mass median diameter of 10 urn,while inlet velocity range was 12-36 m/s.Both the separation efficiency and pressure drop of the cyclone were measured as a function of the inlet velocity and operating temperature.At the same inlet velocity,both the separation efficiency and pressure drop decrease with increasing temperature.In addition,optimum inlet velocity,at which the cyclone has its highest separation efficiency,tends to increase with a rise in temperature.An analysis on our own data and published results has shown that the fractional efficiency of a cyclone is a definite function of dimensionless numbers such as the Stokes number,the Reynolds number,the Froude number,dimensionless cyclone inlet area,and dimensionless outlet diameter.A nondimensional experimental correlation of the cyclone performance,including the influence of temperature,was obtained on the basis of our own previous work.The prediction of the influence of temperature on separation efficiencies and pressure drops is in fairly good agreement with experimental results.

  7. The contribution of tropical cyclones to rainfall in Mexico

    Science.gov (United States)

    Agustín Breña-Naranjo, J.; Pedrozo-Acuña, Adrián; Pozos-Estrada, Oscar; Jiménez-López, Salma A.; López-López, Marco R.

    Investigating the contribution of tropical cyclones to the terrestrial water cycle can help quantify the benefits and hazards caused by the rainfall generated from this type of hydro-meteorological event. Rainfall induced by tropical cyclones can enhance both flood risk and groundwater recharge, and it is therefore important to characterise its minimum, mean and maximum contributions to a region or country's water balance. This work evaluates the rainfall contribution of tropical depressions, storms and hurricanes across Mexico from 1998 to 2013 using the satellite-derived precipitation dataset TMPA 3B42. Additionally, the sensitivity of rainfall to other datasets was assessed: the national rain gauge observation network, real-time satellite rainfall and a merged product that combines rain gauges with non-calibrated space-borne rainfall measurements. The lower Baja California peninsula had the highest contribution from cyclonic rainfall in relative terms (∼40% of its total annual rainfall), whereas the contributions in the rest of the country showed a low-to-medium dependence on tropical cyclones, with mean values ranging from 0% to 20%. In quantitative terms, southern regions of Mexico can receive more than 2400 mm of cyclonic rainfall during years with significant TC activity. Moreover, (a) the number of tropical cyclones impacting Mexico has been significantly increasing since 1998, but cyclonic contributions in relative and quantitative terms have not been increasing, and (b) wind speed and rainfall intensity during cyclones are not highly correlated. Future work should evaluate the impacts of such contributions on surface and groundwater hydrological processes and connect the knowledge gaps between the magnitude of tropical cyclones, flood hazards, and economic losses.

  8. Cyclone formation and development in the Antarctic Prydz Bay

    Institute of Scientific and Technical Information of China (English)

    解思梅; 梅山; 刘克威; 魏立新

    2002-01-01

    Using meteorological data of field observation in 1990~ 2000 , especially polar orbit highresolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncomplete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calculated. In the open water area, momentum flux is - 2.205 N/m2, sensible heat flux is 486.69 W/m2, and latent heat flux is 261.84 W/m2. It is larger than values of westerlies burst over the Pacific. The heat transferred from ocean to atmosphere in form of sensible and latent heat promotes cyclone development rapidly. In this case wind force was as strong as 12 grade, with 10 minutes average wind speed of 38 m/s, and instantaneous wind speed of 100 m/s which broke the wind speed record of 96 m/s in the Antarctic (Wendler and Kodama).

  9. 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 wind events can be defined via different percentile values of the windspeed (e.g. above the 95 percentile). By this means the relationship between strong wind events and cyclones is also investigated. For several regions (e.g. Germany, France, Spain) a shift to more deep cyclones connected with an increasing number of strong wind events is found.

  10. Why Do Model Tropical Cyclones Grow Progressively in Size and Decay in Intensity after Reaching Maturity

    Science.gov (United States)

    2015-08-17

    TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 1–16 (2015) Meteorological Institute Ludwig Maximilians University of Munich Why do model tropical cyclones ...behaviour of tropical cyclones in the prototype problem for cyclone intensification on an f -plane is examined using a nonhydrostatic, three-dimensional...controlling the evolution of size and intensity of a tropical cyclone . It provides also a plausible, and arguably simpler, explanation for the expansion

  11. A statistical assessment of tropical cyclone activity in atmospheric general circulation models

    OpenAIRE

    Suzana J. Camargo; Barnston, Anthony G; Zebiak, Stephen E.

    2005-01-01

    The properties of tropical cyclones in three low-resolution atmospheric general circulation models (AGCMs) in seven ocean basins are discussed. The models are forced by prescribed, observed sea surface temperatures over a period of 40 yr, and their simulations of tropical cyclone activity are compared with observations. The model cyclone characteristics considered include genesis position, number of cyclones per year, seasonality, accumulated cyclone energy, track locations, and number of sto...

  12. Coastal flooding by tropical cyclones and sea-level rise.

    Science.gov (United States)

    Woodruff, Jonathan D; Irish, Jennifer L; Camargo, Suzana J

    2013-12-05

    The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence.

  13. Two parametric tropical cyclone models for storm surge modeling

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-li

    2010-01-01

    In this paper,the two parametric tropical cyclone models for storm surge modeling are further developed.The analytical expressions of tangential and radial velocity distribution are derived from the governing momentum equations,based on the general symmetric pressure distribution proposed by Holland and Fujita.On the basis of the data of several tropical cyclones that occurred in East China Ocean,the shape parameter in pressure model is estimated.Finally,the Fred cyclone(typhoon 199417)is calculated,and comparisons of measured and calculated air pressures and wind speed are presented.

  14. Study of a Novel Rotary Cyclone Gas-Solid Separator

    Institute of Scientific and Technical Information of China (English)

    Zhiguang Ling; Xingyong Deng

    2003-01-01

    Based on the analytical study of the characteristics of fine particle motion in swirling flow, a new design idea on flow organization and construction aimed at increasing the positive radial flow in the separation chamber of the rotary cyclone separator (PRV type) was proposed. Experimental verification including the test of variation of separation efficiency and pressure loss with the first and secondary flow ratio show that this new type separator has higher and more stable separation efficiency in broad flow ratio range while the pressure loss is far below the conventional rotary cyclone separator and even comparable with that of simple cyclone separator

  15. Study on Non-Collision Mineralizing Mechanism of Froth Cyclone

    Institute of Scientific and Technical Information of China (English)

    董平; 许占贤; 周晓玲

    2002-01-01

    On the basis of the mineralizing mechanism of froth cyclone, this paper expounds that the froth cyclone flotation process is accomplished in a limited centrifugal field. The main feature of air bubble mineralizing in the froth cyclone is a synthetic mineralizing process, of which the non-collision mineralization of minute air bubble separated out dominates, supplemented with the collision mineralization. Moreover, this paper points out that the hydrophobic separated out and centrifugal force strengthen the selectivity of fine coal particle, accelerate the flotation speed and improve the slime recovery.

  16. Mediterranean cyclone characteristics related to precipitation occurrence in Crete, Greece

    OpenAIRE

    Iordanidou, V.; A. G. Koutroulis; I. K. Tsanis

    2015-01-01

    The characteristics of the cyclone tracks that caused precipitation events of variable intensity for the period 1979–2011 over the island of Crete are presented. The data set used for cyclone identification is the 0.5° × 0.5°, 30 years European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim mean sea-level pressure. Cyclone characteristics are calculated with the aid of the Melbourne University algorithm (MS scheme). Daily precipitation data from a dense gaugi...

  17. Tropical cyclones and climate change; Les cyclones tropicaux et le changement climatique

    Energy Technology Data Exchange (ETDEWEB)

    Andre, J.C. [Centre Europeen de Recherches Avancees en Calcul Scientifique, 31 - Toulouse (France); Royer, J.F.; Chauvin, F. [Meteo-France, Centre National de Recherches Meteorologique (CNRM), 31 - Toulouse (France)

    2008-09-15

    Results from observations and modelling studies, a number of which having been used to support the conclusions of the IPCC fourth assessment report, are presented. For the past and present-day (since 1970) periods, the increase of strong cyclonic activity over the North Atlantic Ocean appears to be in good correlation with increasing temperature of the ocean surface. For regions where observational data are of lesser quality, the increasing trend is less clear. In fact, assessing long-term changes is made difficult due to both the multi-decennial natural variability and the lesser coverage of observations before satellites were made available. Indirect observational data, such as those derived from quantitative estimations of damage caused by tropical cyclones, suffer from many artefacts and do not allow the resolving of the issue either. For the future, only numerical three-dimensional climate models can be used. They nevertheless run presently with too-large grid-sizes, so that their results are still not converging. Various simulations lead indeed to different results, and it is very often difficult to find the physical reasons for these differences. One concludes by indicating some ways through which numerical simulations could be improved, leading to a decrease of uncertainties affecting the prediction of cyclonic activity over the next decades. (authors)

  18. Extreme midlatitude cyclones and their implications for precipitation and wind speed extremes in simulations of the Maunder Minimum versus present day conditions

    Energy Technology Data Exchange (ETDEWEB)

    Raible, C.C.; Casty, C. [University of Bern, Climate and Environmental Physics, Physics Institute, Bern (Switzerland); Yoshimori, M. [University of Bern, Climate and Environmental Physics, Physics Institute, Bern (Switzerland); Rutgers University, Center for Environmental Prediction, New Brunswick, NJ (United States); Stocker, T.F. [University of Bern, Climate and Environmental Physics, Physics Institute, Bern (Switzerland); University of Hawaii, International Pacific Research Center, SOEST, Honolulu, HI (United States)

    2007-03-15

    Extreme midlatitude cyclone characteristics, precipitation, wind speed events, their inter-relationships, and the connection to large-scale atmospheric patterns are investigated in simulations of a prolonged cold period, known as the Maunder Minimum from 1640 to 1715 and compared with today. An ensemble of six simulations for the Maunder Minimum as well as a control simulation for perpetual 1990 conditions are carried out with a coupled atmosphere-ocean general circulation model, i.e., the Climate Community System Model (CCSM). The comparison of the simulations shows that in a climate state colder than today the occurrence of cyclones, the extreme events of precipitation and wind speed shift southward in all seasons in the North Atlantic and the North Pacific. The extremes of cyclone intensity increases significantly in winter in almost all regions, which is related to a stronger meridional temperature gradient and an increase in lower tropospheric baroclinicity. Extremes of cyclone intensity in subregions of the North Atlantic are related to extremes in precipitation and in wind speed during winter. Moreover, extremes of cyclone intensity are also connected to distinct large-scale atmospheric patterns for the different subregions, but these relationships vanish during summer. Analyzing the mean 1,000 hPa geopotential height change of the Maunder Minimum simulations compared with the control simulation, we find a similar pattern as the correlation pattern with the cyclone intensity index of the southern Europe cyclones. This illustrates that changes in the atmospheric high-frequency, i.e., the simulated southward shift of cyclones in the North Atlantic and the related increase of extreme precipitation and wind speed in particular in the Mediterranean in winter, are associated with large-scale atmospheric circulation changes. (orig.)

  19. Targeted ocean sampling guidance for tropical cyclones

    Science.gov (United States)

    Chen, Sue; Cummings, James A.; Schmidt, Jerome M.; Sanabia, Elizabeth R.; Jayne, Steven R.

    2017-05-01

    A 3-D variational ocean data assimilation adjoint approach is used to examine the impact of ocean observations on coupled tropical cyclone (TC) model forecast error for three recent hurricanes: Isaac (2012), Hilda (2015), and Matthew (2016). In addition, this methodology is applied to develop an innovative ocean observation targeting tool validated using TC model simulations that assimilate ocean temperature observed by Airborne eXpendable Bathy Thermographs and Air-Launched Autonomous Micro-Observer floats. Comparison between the simulated targeted and real observation data assimilation impacts reveals a positive maximum mean linear correlation of 0.53 at 400-500 m, which implies some skill in the targeting application. Targeted ocean observation regions from these three hurricanes, however, show that the largest positive impacts in reducing the TC model forecast errors are sensitive to the initial prestorm ocean conditions such as the location and magnitude of preexisting ocean eddies, storm-induced ocean cold wake, and model track errors.

  20. A global climate model based, Bayesian climate projection for northern extra-tropical land areas

    Science.gov (United States)

    Arzhanov, Maxim M.; Eliseev, Alexey V.; Mokhov, Igor I.

    2012-04-01

    Projections with contemporary global climate models (GCMs) still markedly deviate from each other on magnitude of climate changes, in particular, in middle to subpolar latitudes. In this work, a climate projection based on the ensemble of 18 CMIP3 GCM models forced by SRES A1B scenario is performed for the northern extra-tropical land. To assess the change of soil state, off-line simulations are performed with the Deep Soil Simulator (DSS) developed at the A.M.Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS). This model is forced by output of the above-mentioned GCM simulations. Ensemble mean and ensemble standard deviation for any variable are calculated by using Bayesian averaging which allows to enhance a contribution from more realistic models and diminish that from less realistic models. As a result, uncertainty for soil and permafrost variables become substantially narrower. The Bayesian weights for each model are calculated based on their performance for the present-day surface air temperature (SAT) and permafrost distributions, and for SAT trend during the 20th century. The results, except for intra-ensemble standard deviations, are not very sensitive to particular choice of Bayesian traits. Averaged over the northern extra-tropical land, annual mean surface air temperature in the ensemble increases by 3.1 ± 1.4 K (ensemble mean±intra-ensemble standard deviation) during the 21st century. Precipitation robustly increases in the pan-Arctic and decreases in the Mediterranean/Black Sea region. The models agree on near-surface permafrost degradation during the 21st century. The area underlain by near-surface permafrost decreases from the contemporary value 20 ± 3 mln sq. km to 14 ± 3 mln sq. km in the late 21st century. This leads to risk for geocryological hazard due to soil subsidence. This risk is classified as moderate to high in the southern and western parts of Siberia and Tibet in Eurasia, and in the region from Alaska

  1. The interannual leading modes of the extratropical variability in the Southern Hemisphere simulated by the ECHAM-4 atmospheric model

    Energy Technology Data Exchange (ETDEWEB)

    Carril, A.F. [ISAO, Istituto di Scienze dell' Atmosfera e dell' Oceano, Bologna (Italy); Navarra, A. [INGV, Istituto Nazionale di Geofisicae Vulcanologia, Rome (Italy)

    2001-11-01

    An ensemble of twenty-three 14-year experiments conducted with the ECHAM-4 GCM has been examined to test the model's capability to simulate the principal modes of interannual variability. The integrations were performed under specified monthly SST between 1979-1993. The analysis was focused on the Southern Hemisphere (SH) extratropics. Empirical orthogonal functions analysis (EOF) using seasonal anomaly fields has been performed to isolate the principal modes that dominate the southern extratropical variability at the interannual time scale. Leading patterns of 500 hPa geopotential height (z500) have been compared with those estimated from the ECMWF re-analysis dataset. The model is able to adequately reproduce the spatial pattern of the annular mode, but it represents the temporal variations of the oscillation less satisfactorily. The model simulation of the Pacific South American (PSA) pattern is better, both in the shape of the pattern and in the temporal evolution. To verify if the capability of the model to adequately simulate the temporal oscillation of the propagating patterns is related to the increased influence of the tropical external forcing, covarying SST-atmospheric modes have been identified by singular value decomposition (SVD). In winter (July-August-September, JAS) the tropical SST variability is highly correlated with the ENSO mode. In summer (January-February-March, JFM) the strength of the teleconnections is related to strong westerly anomalies, disrupted by a meridional out of phase relation near to South America. The large size of the ensemble was exploited by comparing the time-varying model spread and degrees of freedom of the simulated extratropical circulation. Results show that when the extratropical circulation has a few degrees of freedom, the reproducibility is relatively low and the ensemble is governed by a fairly robust zonally symmetric structure of dispersion. (orig.)

  2. Operation of a cyclonic preheater in the Ca-looping for CO2 capture.

    Science.gov (United States)

    Martínez, Ana; Lara, Yolanda; Lisbona, Pilar; Romeo, Luis M

    2013-10-01

    Calcium looping is an emerging technology for CO2 capture that makes use of the calcium oxide as a sorbent. One of its main issues is the significant energy consumption in the calciner, where the regeneration of the sorbent takes place. Nevertheless, as a high temperature looping technology, the surplus heat flows may be used to reduce the energy needs in this reactor. The addition of a cyclonic preheater similar to those used in the cement industry is proposed in this work. A calcium looping system was modeled and simulated to assess the advantages and disadvantages of the inclusion of a cyclonic preheater. Despite the negative effect on the maximum average capture capacity of the sorbent, a reduction on the coal and oxygen consumptions and on the extra CO2 generated in the calciner is obtained.

  3. Low NO sub x /SO sub x Burner retrofit for utility cyclone boilers

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    This Public Design Report provides available nonproprietary design information on the Low NO{sub x}SO{sub x} Burner Retrofit of Utility Cyclone Boilers project. In addition to the design aspects, the history of the project, the organization of the project, and the role of the funding parties are discussed. An overview of the Low NO{sub x}SO{sub x} (LNS) Burner, the cyclone boiler and the Southern Illinois Power Cooperative host site is presented. A detailed nonproprietary description of the individual process steps, plant systems, and resulting performance then follows. Narrative process descriptions, simplified process flow diagrams, input/output stream data, operating conditions and requirements are given for each unit. The plant demonstration program and start up provisions, the environmental considerations and control, monitoring and safety factors that are considered are also addressed.

  4. Natural disaster management in India with focus on floods and cyclones

    Science.gov (United States)

    Thattai, Deeptha V.; Sathyanathan, R.; Dinesh, R.; Harshit Kumar, L.

    2017-07-01

    Disasters are of two major kinds, natural and manmade, and affect the community. Natural disasters are caused by natural earth processes like floods, droughts, cyclones, tsunamis, earthquakes and epidemics. Manmade disasters occur due to chemical spills, accidents, terrorism activities etc. India is prone to almost all the major natural disasters. The high population density combined with poor preparedness, planning and management, and rescue and relief measures inevitably lead to huge losses of lives and property every year in the country. This paper analyses the disaster management policy of India and its implementation using two recent case studies - one where a relative degree of success has been achieved (cyclones) and the other where we are still struggling to have even a basic preparedness system in place (floods).

  5. Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall

    DEFF Research Database (Denmark)

    Doyle, Samuel H.; Hubbard, Alun; van de Wal, Roderik S.W.

    2015-01-01

    Intense rainfall events significantly affect Alpine and Alaskan glaciers through enhanced melting, ice-flow acceleration and subglacial sediment erosion, yet their impact on the Greenland ice sheet has not been assessed. Here we present measurements of ice velocity, subglacial water pressure...... and meteorological variables from the western margin of the Greenland ice sheet during a week of warm, wet cyclonic weather in late August and early September 2011. We find that extreme surface runoff from melt and rainfall led to a widespread acceleration in ice flow that extended 140 km into the ice-sheet interior....... We suggest that the late-season timing was critical in promoting rapid runoff across an extensive bare ice surface that overwhelmed a subglacial hydrological system in transition to a less-efficient winter mode. Reanalysis data reveal that similar cyclonic weather conditions prevailed across southern...

  6. The evacuation of cairns hospitals due to severe tropical cyclone Yasi.

    Science.gov (United States)

    Little, Mark; Stone, Theona; Stone, Richard; Burns, Jan; Reeves, Jim; Cullen, Paul; Humble, Ian; Finn, Emmeline; Aitken, Peter; Elcock, Mark; Gillard, Noel

    2012-09-01

    On February 2, 2011, Tropical Cyclone Yasi, the largest cyclone to cross the Australian coast and a system the size of Hurricane Katrina, threatened the city of Cairns. As a result, the Cairns Base Hospital (CBH) and Cairns Private Hospital (CPH) were both evacuated, the hospitals were closed, and an alternate emergency medical center was established in a sports stadium 15 km from the Cairns central business district. This article describes the events around the evacuation of 356 patients, staff, and relatives to Brisbane (approximately 1,700 km away by road), closure of the hospitals, and the provision of a temporary emergency medical center for 28 hours during the height of the cyclone. Our experience highlights the need for adequate and exercised hospital evacuation plans; the need for clear command and control with identified decision-makers; early decision-making on when to evacuate; having good communication systems with redundancy; ensuring that patients are adequately identified and tracked and have their medications and notes; ensuring adequate staff, medications, and oxygen for holding patients; and planning in detail the alternate medical facility safety and its role, function, and equipment.

  7. Pressure Drop in Cyclone Separator at High Pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    For the design of pressurized circulating fluidized beds, experiments were conducted in a small cyclone with 120 mm in diameter and 300 mm in height at high pressures and at atmospheric temperatures. Influence of air leakage from the stand pipe into the cyclone was specially focused. A semi-empirical model was developed for the predic tion of the pressure drop of the cyclone separator at different operate pressures with the effect of air leakage and inlet solid loading. The operate pressure, air leakage and inlet solid loading act as significant roles in cyclone pressure drop. The pressure drop increases with the increasing of pressure and decreases with the increasing of the flow rate of air leakage from the standpipe and with the increasing of the inlet solid loading.

  8. Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India)

    Science.gov (United States)

    Reuter, M.; Piller, W. E.; Harzhauser, M.; Kroh, A.

    2013-09-01

    Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin) as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27-24 Ma). Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system at the Oligocene-Miocene boundary. The vast shell concentrations are comprised of a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deeper to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished, each recording a relative storm wave base. (1) A shallow storm wave base is shown by nearshore molluscs, reef corals and Clypeaster echinoids; (2) an intermediate storm wave base depth is indicated by lepidocyclinid foraminifers, Eupatagus echinoids and corallinacean algae; and (3) a deep storm wave base is represented by an Amussiopecten bivalve-Schizaster echinoid assemblage. These wave base depth estimates were used for the reconstruction of long-term tropical storm intensity during the late Oligocene. The development and intensification of cyclones over the recent Arabian Sea is primarily limited by the atmospheric monsoon circulation and strength of the associated vertical wind shear. Therefore, since the topographic boundary conditions for the Indian monsoon already existed in the late Oligocene, the reconstructed long-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~ 26 Ma followed by a period of monsoon weakening during the peak of the late

  9. Cyclone trends constrain monsoon variability during late Oligocene sea level highstands (Kachchh Basin, NW India

    Directory of Open Access Journals (Sweden)

    M. Reuter

    2013-09-01

    Full Text Available Climate change has an unknown impact on tropical cyclones and the Asian monsoon. Herein we present a sequence of fossil shell beds from the shallow-marine Maniyara Fort Formation (Kachcch Basin as a recorder of tropical cyclone activity along the NW Indian coast during the late Oligocene warming period (~ 27–24 Ma. Proxy data providing information about the atmospheric circulation dynamics over the Indian subcontinent at this time are important since it corresponds to a major climate reorganization in Asia that ends up with the establishment of the modern Asian monsoon system at the Oligocene–Miocene boundary. The vast shell concentrations are comprised of a mixture of parautochthonous and allochthonous assemblages indicating storm-generated sediment transport from deeper to shallow water during third-order sea level highstands. Three distinct skeletal assemblages were distinguished, each recording a relative storm wave base. (1 A shallow storm wave base is shown by nearshore molluscs, reef corals and Clypeaster echinoids; (2 an intermediate storm wave base depth is indicated by lepidocyclinid foraminifers, Eupatagus echinoids and corallinacean algae; and (3 a deep storm wave base is represented by an Amussiopecten bivalve-Schizaster echinoid assemblage. These wave base depth estimates were used for the reconstruction of long-term tropical storm intensity during the late Oligocene. The development and intensification of cyclones over the recent Arabian Sea is primarily limited by the atmospheric monsoon circulation and strength of the associated vertical wind shear. Therefore, since the topographic boundary conditions for the Indian monsoon already existed in the late Oligocene, the reconstructed long-term cyclone trends were interpreted to reflect monsoon variability during the initiation of the Asian monsoon system. Our results imply an active monsoon over the Eastern Tethys at ~ 26 Ma followed by a period of monsoon weakening during the

  10. Sediment transport off Bangladesh: the power of tropical cyclones recorded in a submarine canyon

    Science.gov (United States)

    Meyer, I.; Kudrass, H.; Palamenghi, L.

    2011-12-01

    Marine sediments offshore Bangladesh are mainly supplied by the Ganges-Brahmaputra river system and are accumulated on the shelf of Bangladesh. The average sediment discharge of the world's biggest river system is estimated to be 0.8-1 billion tons per year. The shallow shelf is cut by a steep and up to 1000 m deep anaerobic canyon, called the "Swatch of No Ground", which acts as a sediment trap. An extremely high annual sedimentation flux of 20-45 cm was determined for the last 50 years by 137Cs and 210Pb measurements. In order to investigate the sediment transport in the Bay of Bengal a marine sediment core was taken from the mid-part of the Swatch of No Ground (21°18N/89°34E) and analyzed for element composition and grain-size distributions. Results show a sequence of graded fine-sand-silt-clay layers. These sequences can be directly related to the historical record of tropical storms, which move across the northern Bay of Bengal during pre- and post-monsoon flood peak and mobilize huge amounts of the shallow marine and coastal sediments into turbid hyperpycnal water masses. Due to the anti-clockwise rotation of the cyclones and their northward path the main transport direction is westward. The coarse grained sediment, remobilized by storm waves, is supported by cyclone-induced currents toward the canyon while the fine grained fraction follows afterward supported by the storm swell plus the semi-diurnal tidal component. Despite the high riverine input the amount of sediment mobilized during normal weather conditions is minimal compared to the sediment mobilized by the cyclonic high-energy input. Similar cyclone-induced sediment transport probably also governs erosion and deposition in most tropical shelf areas affected by the monsoon regime.

  11. Recent Developments in the Fluid Dynamics of Tropical Cyclones

    Science.gov (United States)

    Montgomery, Michael T.; Smith, Roger K.

    2017-01-01

    This article reviews progress in understanding the fluid dynamics and moist thermodynamics of tropical cyclone vortices. The focus is on the dynamics and moist thermodynamics of vortex intensification and structure. We discuss previous ideas on many facets of the subject and articulate also some open questions. The advances reviewed herein provide new insight and tools for interpreting complex vortex-convective phenomenology in simulated and observed tropical cyclones.

  12. Simulation of Extreme Arctic Cyclones in IPCC AR5 Experiments

    Science.gov (United States)

    2014-05-15

    emerge in the interior Arctic Ocean, especially over regions where sea ice loss exposes open water. However, this change is not effected by the...htm> Scientific American ("Warming Arctic spurs cyclones and sea ice loss "), < http://www.scientificamerican.com/article/warming- arctic -spurs...cyclones-and-sea- ice - loss /?&WT.mc_id=SA_DD_20140220> Nelson Institute of Environmental Studies at University of Wisconsin feature ("More extreme Arctic

  13. NUMERICAL SIMULATIONS OF β-GYRES IN TROPICAL CYCLONES

    Institute of Scientific and Technical Information of China (English)

    杨洪波; 张铭

    2003-01-01

    The circulation of β-gyres in tropical cyclones is studied using numerical simulations. As shown in the result, there is clear circulation of β-gyres in the deviation flow field of the middle layer of the model,i.e. there is cyclone current west of the vortex center but anticyclone current east of it. The theory analysis shows that the circulation of β-gyres is formed by the advection of geostrophic vorticity.

  14. Statistical Aspects of North Atlantic Basin Tropical Cyclones During the Weather Satellite Era, 1960-2013: Part 1

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    A tropical cyclone is described as a warm-core, nonfrontal, synoptic-scale system that originates over tropical or subtropical waters, having organized deep convection and closed surface wind circulation (counterclockwise in the Northern Hemisphere) about a well defined center. When its sustained wind speed equals 34-63 kt, it is called a tropical (or subtropical) storm and is given a name (i.e., alternating male and female names, beginning in 1979); when its sustained wind speed equals 64-95 kt, it is called a hurricane (at least in the Eastern Pacific and North Atlantic basin); and when its sustained wind speed equals 96 kt or higher, it is called an intense or major hurricane (i.e., categories 3-5 on the Saffir-Simpson Hurricane Wind Scale). Although tropical cyclones have been reported and described since the voyages of Columbus, a detailed record of their occurrences extends only from 1851 to the present, with the most reliable portion extending only from about 1945 to the present, owing to the use of near-continuous routine reconnaissance aircraft monitoring flights and the use of satellite imagery (beginning in 1960; see Davis). Even so, the record may still be incomplete, possibly missing at least one tropical cyclone per yearly hurricane season, especially prior to the use of continuous satellite monitoring. In fact, often an unnamed tropical cyclone is included in the year-end listing of events at the conclusion of the season, following post-season analysis (e.g., as happened in 2011 and 2013, each having one unnamed event). In this two-part Technical Publication (TP), statistical aspects of the North Atlantic basin tropical cyclones are examined for the interval 1960-2013, the weather satellite era. Part 1 examines some 25 parameters of tropical cyclones (e.g., frequencies, peak wind speed (PWS), accumulated cyclone energy (ACE), etc.), while part 2 examines the relationship of these parameters against specific climate-related factors. These studies are

  15. An intimate coupling of ocean-atmospheric interaction over the extratropical North Atlantic and Pacific

    Science.gov (United States)

    Li, Chun; Wu, Lixin; Wang, Qi; Qu, Liwei; Zhang, Liping

    2009-05-01

    The inter-basin teleconnection between the North Atlantic and the North Pacific ocean-atmosphere interaction is studied using a coupled ocean-atmosphere general circulation model. In the model, an idealized oceanic temperature anomaly is initiated over the Kuroshio and the Gulf Stream extension region to track the coupled evolution of ocean and atmosphere interaction, respectively. The experiments explicitly demonstrate that both the North Pacific and the North Atlantic ocean-atmosphere interactions are intimately coupled through an inter-basin atmospheric teleconnection. This fast inter-basin communication can transmit oceanic variability between the North Atlantic and the North Pacific through local ocean-to-atmosphere feedbacks. The leading mode of the extratropical atmospheric internal variability plays a dominant role in shaping the hemispheric-scale response forced by oceanic variability over the North Atlantic and Pacific. Modeling results also suggest that a century (two centuries) long observations are necessary for the detection of Pacific response to Atlantic forcings (Atlantic response to Pacific forcing).

  16. Partial Whitening SVD Analysis and its application to tropical-extratropical teleconnections

    Science.gov (United States)

    Swenson, Erik

    2014-05-01

    Various multivariate statistical methods have been established and proven useful for isolating relationships between datasets. Many popular linear methods are based on Singular Value Decomposition (SVD) and include Canonical Correlation Analysis (CCA), Maximum Covariance Analysis (MCA), and Redundancy Analysis (RDA). In this study, Partial Whitening SVD Analysis (PWSVD) is introduced as a new technique that maximizes the squared covariance between partially-whitened variables. Applied as a pre-filter, the partial whitening transformation acts to decorrelate and normalize individual variables to a fractional degree that is specified prior. Particular PWSVD solutions include a new and effective regularization for CCA as well a variance bias correction for MCA. Also, given some crude prior expectation of the signal-to-noise, asymmetric PWSVD solutions can provide significant benefit, and the full range of solutions bridges those of CCA, MCA and RDA. After deriving PWSVD, it is used to linearly relate precipitation in the tropical Pacific with Northern Hemisphere extratropical circulation during boreal winter, and solutions are contrasted with those of traditional methods. It is demonstrated that PWSVD produces a highly robust representation of the dominant teleconnections, namely ENSO and ENSO Modoki, or flavors of ENSO. Lastly, the practical use of PWSVD is encouraged for a range of applications.

  17. Has influence of extratropical waves in modulating Indian summer monsoon rainfall (ISMR) increased?

    Indian Academy of Sciences (India)

    A K Srivastava; Somenath Dutta; S R Kshirsagar; Kavita Srivastava

    2014-04-01

    In the paper, influence of extratropical circulation features on Indian Summer Monsoon Rainfall (ISMR) is examined. Energetics of extra tropics, north of Indian subcontinent for deficient and nondeficient ISMR years, during two periods 1951–1978 and 1979–2005, are calculated and critically analyzed. It is observed that for the period 1951–1978, only two out of the 10 energetic parameters, viz., the zonal available potential energy (high) and conversion of zonal available potential with kinetic energy to eddy kinetic energy (low) differed significantly in JJA months of the deficient years from that of the nondeficient years. However, during the 1979–2005 period, as many as six out of the 10 energetic parameters, viz., eddy available potential energy, zonal available potential energy, eddy kinetic energy, generation of zonal available potential energy, conversion of zonal available potential energy to zonal kinetic energy and conversion of zonal kinetic energy to eddy kinetic energy differed significantly in JJA months of the deficient years from that of the nondeficient years. These results confirm growing influence of the transient stationary waves in deficient years after the climate shift year, 1979. Analysis of energetic parameters of the pre-monsoon season of the two periods also reveals similar results. This suggests that forcings apparently responsible for energetics in JJA months of the deficient years of the later period were present even before the advent of Indian summer monsoon season.

  18. Tropical cyclone activity over the Southwest Tropical Indian Ocean

    Science.gov (United States)

    Burns, Jessica M.; Subrahmanyam, Bulusu; Nyadjro, Ebenezer S.; Murty, V. S. N.

    2016-08-01

    The Southwest Tropical Indian Ocean (SWTIO) is a key region for air-sea interaction. Tropical cyclones (TCs) regularly form over the SWTIO and subsurface ocean variability influences the cyclogenesis of this region. Tropical cyclone days for this region span from November through April, and peak in January and February during austral summer. Past research provides evidence for more tropical cyclone days over the SWTIO during austral summer (December-June) with a deep thermocline ridge than in austral summer with a shallow thermocline ridge. We have analyzed the Argo temperature data and HYbrid Coordinate Ocean Model (HYCOM) outputs while focusing on the austral summer of 2012/2013 (a positive Indian Ocean Dipole (IOD) year and neutral El Niño Southern Oscillation (ENSO) year) when seven named tropical cyclones developed over the SWTIO region. This study reveals that the climatic events like the IOD and ENSO influence the cyclonic activity and number of TC days over the SWTIO. We ascertain that the IOD events have linkages with the Barrier Layer Thickness (BLT) in the SWTIO region through propagating Rossby waves, and further show that the BLT variability influences the cyclonic activity in this region.

  19. Improvement of wind field hindcasts for tropical cyclones

    Directory of Open Access Journals (Sweden)

    Yi Pan

    2016-01-01

    Full Text Available This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the Cross-Calibrated Multi-Platform (CCMP reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

  20. Influences of Tropical Cyclones on China During 1965-2004

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaoling; WU Liguang; REN Fumin; WANG Yongmei; LI Weijing

    2008-01-01

    Using the Joint Typhoon Warning Center (JTWC) and China Meteorological Administration (CMA) tropical cyclone track datasets, variations in frequency and intensity of the affecting-China tropical cyclones (ACTCs) are studied for the period of 1965 2004. First, the differences between the two tropical cyclone datasets are examined. The annual frequencies of tropical cyclones in the western North Pacific basin are reasonably consistent to each other, while the intensity records are less reliable. The annual numbers of ACTCs based on different datasets are close to each other with similar interdecadal and interannual variations. However, the maximum intensity and the annual frequency of ACTCs for strong categories show great dependence on datasets. Tropical cyclone impacts on China show the same variations as the annual number of ACTCs and also show dependence on datasets. Differences in tropical cyclone impacts on China are mainly caused by datasets used. The annual frequency of ACTCs, especially the length of lifetime of ones that make landfall, and the intensity estimates all have effects on the value of impacts on China.

  1. An exemplary case of a bromine explosion event linked to cyclone development in the Arctic

    Science.gov (United States)

    Blechschmidt, A.-M.; Richter, A.; Burrows, J. P.; Kaleschke, L.; Strong, K.; Theys, N.; Weber, M.; Zhao, X.; Zien, A.

    2016-02-01

    Intense, cyclone-like shaped plumes of tropospheric bromine monoxide (BrO) are regularly observed by GOME-2 on board the MetOp-A satellite over Arctic sea ice in polar spring. These plumes are often transported by high-latitude cyclones, sometimes over several days despite the short atmospheric lifetime of BrO. However, only few studies have focused on the role of polar weather systems in the development, duration and transport of tropospheric BrO plumes during bromine explosion events. The latter are caused by an autocatalytic chemical chain reaction associated with tropospheric ozone depletion and initiated by the release of bromine from cold brine-covered ice or snow to the atmosphere. In this manuscript, a case study investigating a comma-shaped BrO plume which developed over the Beaufort Sea and was observed by GOME-2 for several days is presented. By making combined use of satellite data and numerical models, it is shown that the occurrence of the plume was closely linked to frontal lifting in a polar cyclone and that it most likely resided in the lowest 3 km of the troposphere. In contrast to previous case studies, we demonstrate that the dry conveyor belt, a potentially bromine-rich stratospheric air stream which can complicate interpretation of satellite retrieved tropospheric BrO, is spatially separated from the observed BrO plume. It is concluded that weather conditions associated with the polar cyclone favoured the bromine activation cycle and blowing snow production, which may have acted as a bromine source during the bromine explosion event.

  2. Studying Policy Changes in Disaster Management in India: A Tale of Two Cyclones.

    Science.gov (United States)

    Jha, Ayan; Basu, Rivu; Basu, Atreyee

    2016-02-01

    The mainstay of India's disaster management policy until the early 2000s had been relief and rescue operations. The Odisha Super Cyclone (1999) with 10,000 deaths and US $3 billion economic damage provided a rude awakening. Recognizing the importance of preemptive preparedness, the government initiated systematic steps to implement a national framework interlinking economic, environmental, and overall developmental issues for efficient response to and mitigation of disasters. We attempted a critical analysis of this paradigm shift in India's disaster management policy through the prism of 2 cyclones, 14 years apart in time. With improved preparedness and response measures, the death toll in 2013 Cyclone Phailin was 0.5% and the economic loss was about one-third of that during 1999. Concomitant improvements in the technological expertise of the early warning system, an integrated approach at all levels of administration including joint planning with major nongovernmental organizations, and improved community participation were identified as game-changers. An unbelievable 1 million people were evacuated to safety. Our essay aims to highlight key steps in this success and calls for futuristic approaches like insurance programs and gender-sensitive recovery plans. With thorough scrutiny, India's model may well stand to be replicated in resource-restricted settings.

  3. A satellite based study of tropospheric bromine explosion events and their linkages to polar cyclone development

    Science.gov (United States)

    Blechschmidt, Anne-Marlene; Richter, Andreas; Burrows, John P.; Kaleschke, Lars; Strong, Kimberly; Theys, Nicolas; Weber, Mark; Zhao, Xiaoyi; Zien, Achim; Hodges, Kevin I.

    2016-04-01

    Intense, cyclone-like shaped plumes of tropospheric bromine monoxide (BrO) are regularly observed by the UV-vis satellite instruments GOME-2/MetOp-A and SCIAMACHY/Envisat over Arctic and Antarctic sea ice in polar spring. The plumes are associated with an autocatalytic chemical chain reaction involving tropospheric ozone depletion and initiated by the release of bromine from cold brine-covered ice or snow to the atmosphere. This influences atmospheric chemistry as it affects the oxidising capacity of the troposphere through OH production and may also influence the local weather/temperature of the polar atmosphere, as ozone is a major greenhouse gas. Here, we make combined use of satellite retrievals and numerical model simulations to study individual BrO plume cases in the polar atmosphere. In agreement with previous studies, our analysis shows that the plumes are often transported by high latitude cyclones, sometimes over several days despite the short atmospheric lifetime of BrO. Moreover, general characteristics of bromine explosion events linked to transport by polar weather systems, such as frequency, spatial distribution and favourable weather conditions are derived based on a new detection method. Our results show that BrO cyclone transport events are by far more common in the Antarctic than in the Arctic.

  4. Effects of melting ice sheets and orbital forcing on the early Holocene warming in extratropical Northern Hemisphere

    Science.gov (United States)

    zhang, yurui; Renssen, Hans; Seppä, Heikki

    2016-04-01

    The early Holocene is an important climatological period, as it marked the final transition from the last deglaciation to the relatively warm and stable Holocene. Previous studies have analyzed the influence of the demise of the ice sheets and other forcings on the climate system during the Holocene. However, the climate response to the forcings together with the internal feedbacks before 9 ka remains not fully comprehended. In this study, we therefore disentangle how these forcings contributed to climate change during the earliest part of Holocene (11.5-7 ka) by employing the LOVECLIM climate model for both equilibrium and transient experiments. The results of our equilibrium experiments for 11.5 ka reveal that the annual mean temperature at the onset of the Holocene was lower than in the preindustrial era over most of the extratropical Northern Hemisphere. The magnitude of this cooler climate varies regionally and this spatial pattern is suggested by the biologically based proxies as well. In eastern N America and NW Europe the temperatures were 2-5 °C lower than in the preindustrial era as the climate was strongly influenced by the cooling effects of the ice sheets at here. This cooling of the ice-sheet surface was caused both by the enhanced surface albedo and by the orography of the ice sheets. In contrast, in Alaska, temperatures in all seasons were 0.5-3 °C higher than in the control run primarily due to the orbitally induced positive insolation anomaly and the enhanced southerly winds which advected warm air from the South as a response to the high air pressure over the Laurentide Ice Sheet (LIS). Our transient experiments indicate that the Holocene temperature evolution and the early Holocene warming were also geographically heterogeneous. In Alaska, the climate is constantly cooling over the whole Holocene. In contrast, in N Canada, there was an overall warming during the early Holocene up to 1.88 °C ka-1 in summer as a consequence of the progressive

  5. Classification of extratropical cyclogenesis events based on a set of precursors

    Science.gov (United States)

    Graf, Michael; Sprenger, Michael; Wernli, Heini

    2014-05-01

    Many studies indicate a large variability of the relevant physical processes (so-called precursors) responsible for cyclogenesis. In this study, potential precursors for cyclogenesis are systematically and comprehensibly investigated on a statistical basis. For this reason, cyclones are objectively identified during the time period 2000-2011 in the ERA-interim dataset and then tracked along their life cycle. The starting points of these tracks are considered as the points of cyclogenesis. In the environment of these cyclogenesis locations a set of about 30 potential precursors is determined. The set includes the following parameters: (a) the surface conditions and fluxes (e.g., sensible and latent heat fluxes, sea surface temperature); (b) characteristic conditions in the troposphere (e.g., vertically integrated water vapor, amplitude of low-level potential vorticity); (c) measures of baroclinic and convective stability (e.g., horizontal temperature gradients, convective available potential energy, Eady growth rate); and (d) flow patterns and forcings from upper-tropospheric and stratospheric levels (e.g., jet streams and streaks, potential vorticity anomalies). In addition to simple Eulerian characterisations, more advanced diagnostic approaches are applied: Lagrangian backward trajectories, averaged time since oceanic moisture uptake of involved low-level air parcels, and layerwise quasi-geostrophic forcing for vertical motion. In the phase space of these potential precursors - determined for a multitude of cyclones and suitably normalized - a principal component analysis is performed. The first two principal components are used subsequently for the separation of the cyclogenesis events in nine classes. Composites of each class are constructed in order to represent the averaged spatial pattern of the precursors. This statistical approach reveals that the most important separating mechanisms are upper-level forcing and moist processes. They are to a large extent

  6. The Impact of Dry Saharan Air on Tropical Cyclone Intensification

    Science.gov (United States)

    Braun, Scott A.

    2012-01-01

    The controversial role of the dry Saharan Air Layer (SAL) on tropical storm intensification in the Atlantic will be addressed. The SAL has been argued in previous studies to have potential positive influences on storm development, but most recent studies have argued for a strong suppressing influence on storm intensification as a result of dry air, high stability, increased vertical wind shear, and microphysical impacts of dust. Here, we focus on observations of Hurricane Helene (2006), which occurred during the NASA African Monsoon Multidisciplinary Activities (NAMMA) experiment. Satellite and airborne observations, combined with global meteorological analyses depict the initial environment of Helene as being dominated by the SAL, although with minimal evidence that the SAL air actually penetrated to the core of the disturbance. Over the next several days, the SAL air quickly moved westward and was gradually replaced by a very dry, dust-free layer associated with subsidence. Despite the wrapping of this very dry air around the storm, Helene intensified steadily to a Category 3 hurricane suggesting that the dry air was unable to significantly slow storm intensification. Several uncertainties remain about the role of the SAL in Helene (and in tropical cyclones in general). To better address these uncertainties, NASA will be conducting a three year airborne campaign called the Hurricane and Severe Storm Sentinel (HS3). The HS3 objectives are: To obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers (that help to isolate tropical disturbances from hostile environments). To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. The mission objectives will be achieved using

  7. Experimental investigation into the application of a magnetic dense medium cyclone in a production environment / Ilana Katinka Myburgh

    OpenAIRE

    Myburgh, Ilana Katinka

    2001-01-01

    The magnetic dense medium cyclone project was undertaken at Koingnaas Mine on a 250 mm diameter cyclone during 1998 and a 510 mm cyclone during 2000. The aim of the project was to evaluate the performance of a magnetic DM cyclone in a production environment. Previous test work on magnetic DM cyclones were conducted during 1995 and 1996 on small (100 mm) cyclones in a laboratory environment, with medium feed only. Solenoid position, magnetic field strength and medium inlet de...

  8. On tropical cyclone frequency and the warm pool area

    Directory of Open Access Journals (Sweden)

    R. E. Benestad

    2009-04-01

    Full Text Available The proposition that the rate of tropical cyclogenesis increases with the size of the "warm pool" is tested by comparing the seasonal variation of the warm pool area with the seasonality of the number of tropical cyclones. An analysis based on empirical data from the Northern Hemisphere is presented, where the warm pool associated with tropical cyclone activity is defined as the area, A, enclosed by the 26.5°C SST isotherm. Similar analysis was applied to the temperature weighted area AT with similar results.

    An intriguing non-linear relationship of high statistical significance was found between the temperature weighted area in the North Atlantic and the North-West Pacific on the one hand and the number of cyclones, N, in the same ocean basin on the other, but this pattern was not found over the North Indian Ocean. A simple statistical model was developed, based on the historical relationship between N and A. The simple model was then validated against independent inter-annual variations in the seasonal cyclone counts in the North Atlantic, but the correlation was not statistically significant in the North-West Pacific. No correlation, however, was found between N and A in the North Indian Ocean.

    A non-linear relationship between the cyclone number and temperature weighted area may in some ocean basins explain both why there has not been any linear trend in the number of cyclones over time as well as the recent upturn in the number of Atlantic hurricanes. The results also suggest that the notion of the number of tropical cyclones being insensitive to the area A is a misconception.

  9. Impact of cyclone Nilam on tropical lower atmospheric dynamics

    Science.gov (United States)

    Vinay Kumar, P.; Dutta, Gopa; Ratnam, M. V.; Krishna, E.; Bapiraju, B.; Rao, B. Venkateswara; Mohammad, Salauddin

    2016-08-01

    A deep depression formed over the Bay of Bengal on 28 October 2012, and developed into a cyclonic storm. After landfall near the south coast of Chennai, cyclone Nilam moved north-northwestwards. Coordinated experiments were conducted from the Indian stations of Gadanki (13.5°N, 79.2°E) and Hyderabad (17.4°N, 78.5°E) to study the modification of gravity-wave activity and turbulence by cyclone Nilam, using GPS radiosonde and mesosphere-stratosphere-troposphere radar data. The horizontal velocities underwent large changes during the closest approach of the storm to the experimental sites. Hodograph analysis revealed that inertia gravity waves (IGWs) associated with the cyclone changed their directions from northeast (control time) to northwest following the path of the cyclone. The momentum flux of IGWs and short-period gravity waves (1-8 h) enhanced prior to, and during, the passage of the storm (±0.05 m2 s-2 and ±0.3 m2 s-2, respectively), compared to the flux after its passage. The corresponding body forces underwent similar changes, with values ranging between ±2-4 m s-1 d-1 and ±12-15 m s-1 d-1. The turbulence refractivity structure constant ( C n 2 ) showed large values below 10 km before the passage of the cyclone when humidity in the region was very high. Turbulence and humidity reduced during the passage of the storm when a turbulent layer at ~17 km became more intense. Turbulence in the lower troposphere and near the tropopause became weak after the passage of the cyclone.

  10. Inducing Tropical Cyclones to Undergo Brownian Motion

    Science.gov (United States)

    Hodyss, D.; McLay, J.; Moskaitis, J.; Serra, E.

    2014-12-01

    Stochastic parameterization has become commonplace in numerical weather prediction (NWP) models used for probabilistic prediction. Here, a specific stochastic parameterization will be related to the theory of stochastic differential equations and shown to be affected strongly by the choice of stochastic calculus. From an NWP perspective our focus will be on ameliorating a common trait of the ensemble distributions of tropical cyclone (TC) tracks (or position), namely that they generally contain a bias and an underestimate of the variance. With this trait in mind we present a stochastic track variance inflation parameterization. This parameterization makes use of a properly constructed stochastic advection term that follows a TC and induces its position to undergo Brownian motion. A central characteristic of Brownian motion is that its variance increases with time, which allows for an effective inflation of an ensemble's TC track variance. Using this stochastic parameterization we present a comparison of the behavior of TCs from the perspective of the stochastic calculi of Itô and Stratonovich within an operational NWP model. The central difference between these two perspectives as pertains to TCs is shown to be properly predicted by the stochastic calculus and the Itô correction. In the cases presented here these differences will manifest as overly intense TCs, which, depending on the strength of the forcing, could lead to problems with numerical stability and physical realism.

  11. On the Development of Above-Anvil Cirrus Plumes in Extratropical Convection

    Science.gov (United States)

    Homeyer, C. R.; McAuliffe, J. D.; Bedka, K. M.

    2016-12-01

    Expansive cirrus clouds present above the anvils of extratropical convection have been observed in satellite and aircraft-based imagery for several decades. Despite knowledge of their occurrence, the precise mechanisms and atmospheric conditions leading to their formation and maintenance are not entirely known. Here, we examine the formation of these cirrus "plumes" using a combination of satellite imagery, three-dimensional ground-based radar observations, assimilated atmospheric states from a state-of-the-art reanalysis, and idealized numerical simulations with explicitly resolved convection. Using data from ten recent cases (2013-Present), we find that all storms with above-anvil cirrus plumes reach altitudes 1 to 6 km above the tropopause. Thus, it is likely that these clouds represent the injection of cloud material into the lower stratosphere. Comparison of above-anvil cirrus plume cases with ten additional cases of observed tropopause-penetrating convection without plumes reveals that these clouds are associated with large vector differences between the motion of a storm and the environmental wind in the upper troposphere and lower stratosphere (UTLS), suggesting that gravity wave breaking and/or stretching of the tropopause-penetrating cloud are/is more prevalent in plume-producing storms. No relationship is found between above-anvil cirrus plume occurrence and the stability of the lower stratosphere (or tropopause structure) or the duration of stratospheric penetration. Idealized model simulations of tropopause-penetrating convection with small and large magnitudes of storm-relative wind in the UTLS are found to reproduce the established observational relationship and show that frequent gravity wave breaking is the primary mechanism responsible for above-anvil cirrus plume formation.

  12. On the structure of the extra-tropical transition layer from in-situ observations

    Directory of Open Access Journals (Sweden)

    I. Pisso

    2012-10-01

    Full Text Available In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994–2007 were combined to investigate the Extra-tropical Transition Layer (ExTL region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis of the available data provides a working definition of the upper limit of the ExTL based on the upper limit of the region of high vertical CO gradient in PV relative coordinates. A secondary local maximum in vertical O3 gradient can be used a proxy for the lower limit, although it is less clearly defined than that of CO. The sloping isopleths of CO and O3 mixing ratios and the CO mixing ratio gradient are consistent with isopleths in purely dynamical diagnostics such as χ30 d, the proportion of air masses in contact with the PBL within one month and underline the differences between the PV based and chemical tropopauses. The use of tropopause relative coordinates allows different seasons to be analysed together to produce climatological means. The weak dependence of dynamical diagnostics of transport on the absolute values of tracer concentrations makes them a suitable process-oriented tool to evaluate global chemical models and make Lagrangian comparisons.

  13. On the structure of the extra-tropical transition layer from in-situ observations

    Science.gov (United States)

    Pisso, I.; Law, K. S.; Fierli, F.; Haynes, P. H.; Hoor, P.; Palazzi, E.; Ravegnani, F.; Viciani, S.

    2012-10-01

    In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994-2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis of the available data provides a working definition of the upper limit of the ExTL based on the upper limit of the region of high vertical CO gradient in PV relative coordinates. A secondary local maximum in vertical O3 gradient can be used a proxy for the lower limit, although it is less clearly defined than that of CO. The sloping isopleths of CO and O3 mixing ratios and the CO mixing ratio gradient are consistent with isopleths in purely dynamical diagnostics such as χ30 d, the proportion of air masses in contact with the PBL within one month and underline the differences between the PV based and chemical tropopauses. The use of tropopause relative coordinates allows different seasons to be analysed together to produce climatological means. The weak dependence of dynamical diagnostics of transport on the absolute values of tracer concentrations makes them a suitable process-oriented tool to evaluate global chemical models and make Lagrangian comparisons.

  14. Tropical Cyclones Cause CaCO3 Undersaturation of Coral Reef Seawater in a High-CO2 World

    Science.gov (United States)

    Manzello, D.; Enochs, I.; Carlton, R.; Musielewicz, S.; Gledhill, D. K.

    2013-12-01

    Ocean acidification is the global decline in seawater pH and calcium carbonate (CaCO3) saturation state (Ω) due to the uptake of anthropogenic CO2 by the world's oceans. Acidification impairs CaCO3 shell and skeleton construction by marine organisms. Coral reefs are particularly vulnerable, as they are constructed by the CaCO3 skeletons of corals and other calcifiers. We understand relatively little about how coral reefs will respond to ocean acidification in combination with other disturbances, such as tropical cyclones. Seawater carbonate chemistry data collected from two reefs in the Florida Keys before, during, and after Tropical Storm Isaac provide the most thorough data to-date on how tropical cyclones affect the seawater CO2-system of coral reefs. Tropical Storm Isaac caused both an immediate and prolonged decline in seawater pH. Aragonite saturation state was depressed by 1.0 for a full week after the storm impact. Based on current 'business-as-usual' CO2 emissions scenarios, we show that tropical cyclones with high rainfall and runoff can cause periods of undersaturation (Ω strength, frequency, and rainfall of the most severe tropical cyclones with climate change in combination with ocean acidification will negatively impact the structural persistence of coral reefs over this century.

  15. Contrasting tropical cyclone and non-tropical cyclone related rainfall drop size distribution at Darwin, Australia

    Science.gov (United States)

    Deo, Anil; Walsh, Kevin J. E.

    2016-11-01

    In this study the rainfall drop size distribution (DSD) during the passage of seven tropical cyclones (TCs) over Darwin is compared and contrasted with that associated with non-tropical cyclone (non-TC) events, using the impact disdrometer data at the Darwin Atmospheric Radiation and Measurement (ARM) site. The disparity of the DSD with respect to rainfall types (between TC and non-TC conditions) and distance from TC centre is also examined. It is shown that TC DSDs are statistically different from the non-TC DSDs, the former encompassing a larger concentration of small to moderate drop sizes. The TC mass-weighted mean diameter (Dm) is lower than the non-TC values at all rain rates and also for the different precipitation types (convective, transition and stratiform). The TC DSD varies with distance from the TC centre, as rainfall near the TC centre (< 60 km) comprises of relatively smaller drops which are strongly evident at small to moderate rain rates (< 30 mm h- 1). Such variations in the DSD have implications for the parameters used in the algorithm that converts radar reflectivity to rainfall rate in TCs, as well as for the analytical expressions used in describing the observed DSD employed in cloud modelling parameterizations.

  16. Evaluating the Climate Role of Tropical Cyclones Using an Atmospheric General Circulation Model

    Science.gov (United States)

    Winterbottom, H. R.; Pegion, P. J.; Hart, R. E.

    2011-12-01

    A formal assessment and an identification for the global circulation impact of a tropical cyclone (TC) remains in the developmental stages. This area of research was first suggested by Bengtsson et al., [1982], when questions were posed regarding the role of TCs with respect to the poleward transport of heat, moisture, and momentum. To date, much attention has been paid to the role of oceanic heat transport [Emanuel, 2001; Sriver and Huber, 2007; Hart et al., 2007; Liu et al., 2008; Hu and Meehl, 2009]. Fewer studies, however, have identified an explicit role for the TC within the atmosphere, although recent work has begun to quantify the magnitude of that atmospheric footprint from reanalysis datasets [Hart et al., 2007; Schenkel and Hart, 2011]. A recent study by Hart [2011] deduced a statistical relationship between northern hemisphere TC activity (evaluated using both TC count and power dissipation [Emanuel, 2007]) and the subsequent winter climate. Hart [2011] ascertained that there exists a strong (statistical) inverse relationship between the amount of pole-ward TC power-dissipation (e.g., recurving TCs) and the 500-hPa extratropical stationary eddy-temperature flux, and speculated on the physical (and potential nonphysical) explanations for such a relationship. Indeed, the relationship was so strong that it was the most robust predictor of this measure of wind activity amidst all known teleconnection indices. These prior works provide the foundation on which to further explore the TC role in climate. Accordingly, in this study, we diagnose the climatic impact of TCs upon the Earth's general circulation using the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) and the TC vortex removal procedure discussed by Winterbottom and Chassignet [2011]. A series of experiments with and without TCs will be compared. We will evaluate the mean and transient eddy fluxes as a function of a simulation with TCs and a simulation without. We

  17. ANALYSIS ON CYCLONE COLLECTION EFFICIENCIES AT HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Jianyi Chen; Mingxian Shi

    2003-01-01

    In order to predict the influence of operating temperature on cyclone performance, an experimental investigation on particle separation was conducted in a 300 mm diameter, tangential volute-inlet and reverse flow cyclone separator with air heated up to 973 K. The test powder silica has a mean mass diameter of 10 microns and the measured as a function of the inlet velocity and operating temperature. It is shown that at the same inlet velocity both the overall efficiency and fractional efficiency decrease with an increase of temperature. An analysis of our own data and published results has shown that the fractional efficiency of a cyclone is a definite function of such dimensionless numbers as Stokes number, Reynolds number, Froude number and dimensionless cyclone inlet area and dimensionless outlet diameter. A nondimensional experimental correlation of the cyclone performance, including the influence of the temperature, was obtained on the basis of our own previous work. The prediction of the influence of temperature on separation efficiencies is in fairly good agreement with experimental results.

  18. Extreme cyclone events in the Arctic: Wintertime variability and trends

    Science.gov (United States)

    Rinke, A.; Maturilli, M.; Graham, R. M.; Matthes, H.; Handorf, D.; Cohen, L.; Hudson, S. R.; Moore, J. C.

    2017-09-01

    Typically 20-40 extreme cyclone events (sometimes called ‘weather bombs’) occur in the Arctic North Atlantic per winter season, with an increasing trend of 6 events/decade over 1979-2015, according to 6 hourly station data from Ny-Ålesund. This increased frequency of extreme cyclones is consistent with observed significant winter warming, indicating that the meridional heat and moisture transport they bring is a factor in rising temperatures in the region. The winter trend in extreme cyclones is dominated by a positive monthly trend of about 3-4 events/decade in November-December, due mainly to an increasing persistence of extreme cyclone events. A negative trend in January opposes this, while there is no significant trend in February. We relate the regional patterns of the trend in extreme cyclones to anomalously low sea-ice conditions in recent years, together with associated large-scale atmospheric circulation changes such as ‘blockinglike’ circulation patterns (e.g. Scandinavian blocking in December and Ural blocking during January-February).

  19. Contrasting Various Metrics for Measuring Tropical Cyclone Activity

    Directory of Open Access Journals (Sweden)

    Jia-Yuh Yu and Ping-Gin Chiu

    2012-01-01

    Full Text Available Popular metrics used for measuring the tropical cyclone (TC activity, including NTC (number of tropical cyclones, TCD (tropical cyclone days, ACE (accumulated cyclone energy, PDI (power dissipation index, along with two newly proposed indices: RACE (revised accumulated cyclone energy and RPDI (revised power dissipation index, are compared using the JTWC (Joint Typhoon Warning Center best-track data of TC over the western North Pacific basin. Our study shows that, while the above metrics have demonstrated various degrees of discrepancies, but in practical terms, they are all able to produce meaningful temporal and spatial changes in response to climate variability. Compared with the conventional ACE and PDI, RACE and RPDI seem to provide a more precise estimate of the total TC activity, especially in projecting the upswing trend of TC activity over the past few decades, simply because of a better approach in estimating TC wind energy. However, we would argue that there is still no need to find a _ or _ metric for TC activity because different metrics are designed to stratify different aspects of TC activity, and whether the selected metric is appropriate or not should be determined solely by the purpose of study. Except for magnitude difference, the analysis results seem insensitive to the choice of the best-track datasets.

  20. CFB cyclones at high temperature: Operational results and design assessment

    Institute of Scientific and Technical Information of China (English)

    Raf Dewil; Jan Baeyens; Bart Caerts

    2008-01-01

    Pressure drop and cut size measurements are reported for a full scale cyclone operating within a 58 MWth CFB-combustor unit at 775℃.The paper reviews the vast number of equations to calculate the pressure drop and separation efficiency of cyclones, generally for operation at ambient temperature and at low Cs[0.5]. None of the literature correlations predicts the pressure drop with a fair accuracy within the range of experimental operating conditions. The cut size d50 can be estimated using direct empirical methods or using the Stokes number, Stk50. Both methods were used to compare measured and predicted values of d50. With the exception of Muschelknautz and Krambrock, none of the equations made accurate predictions.Finally, an alternative method to determine the friction factor of the pressure drop equation (Euler number, Eu) and of the cut size is proposed. The Eu number is determined from the geometry of common cyclones, and the derived value of Stk50 defines more accurate cut sizes. The remaining discrepancy of less than 5%, when compared with the measured values, is tentatively explained in terms of a reduced cyclone diameter due to the solids layer formed near its wall. Further measurements, mostly using positron emission particle tracking, elucidate the particle motion in the cyclone and both tracking results and the influence of the particle movement on Eu and Stk50 will be discussed in a follow-up paper.

  1. Determination of welding spark parameters for cyclone efficiency calculation (rus

    Directory of Open Access Journals (Sweden)

    Kitain M.B.

    2011-08-01

    Full Text Available Importance of the current work is explained by the problem of air purification in the field of breath of the worker and prevention of the fire and the explosion. To solve this problem the authors offer to use Reverse-flow cyclone as precleaner with spark extinguishing option. In case if the dust includes sparks it is very important to insure that the particles with the sparks will be totally collected in the cyclone, so the collection efficiency for such particles will be 100% in the cyclone. For the estimation of the efficiency of gas purification from the dust particles in the cyclones dust particles features should be determinate, that can be done with the satisfactory accuracy only by physical modeling results. The amount of physical experiments was made by the authors. The methods of determination of the geometric diameter and hydraulic size of the particle consisting sparks were offered. The experimental researches showed that the accuracy of using the geometric diameter of such particle is not enough, because the hydrodynamic characteristics of the particles (such as weight, effective diameter, the way of interaction with the environment can be change in the case of moving. At the same time< hydraulic size, determined in the second part of the experiment, consider all these factors and can be used for the estimation of the cyclone efficiency based on the model of turbulent diffusion with the limited velocity.

  2. Contrasting Various Metrics for Measuring Tropical Cyclone Activity

    Directory of Open Access Journals (Sweden)

    Jia-Yuh Yu Ping-Gin Chiu

    2012-01-01

    Full Text Available Popular metrics used for measuring the tropical cyclone (TC activity, including NTC (number of tropical cyclones, TCD (tropical cyclone days, ACE (accumulated cyclone energy, PDI (power dissipation index, along with two newly proposed indices: RACE (revised accumulated cyclone energy and RPDI (revised power dissipation index, are compared using the JTWC (Joint Typhoon Warning Center best-track data of TC over the western North Pacific basin. Our study shows that, while the above metrics have demonstrated various degrees of discrepancies, but in practical terms, they are all able to produce meaningful temporal and spatial changes in response to climate variability. Compared with the conventional ACE and PDI, RACE and RPDI seem to provide a more precise estimate of the total TC activity, especially in projecting the upswing trend of TC activity over the past few decades, simply because of a better approach in estimating TC wind energy. However, we would argue that there is still no need to find a ¡§universal¡¨ or ¡§best¡¨ metric for TC activity because different metrics are designed to stratify different aspects of TC activity, and whether the selected metric is appropriate or not should be determined solely by the purpose of study. Except for magnitude difference, the analysis results seem insensitive to the choice of the best-track datasets.

  3. SINGULAR SPECTRUM ANALYSIS FOR TROPICAL CYCLONE LANDING IN GUANGDONG

    Institute of Scientific and Technical Information of China (English)

    谢炯光; 纪忠萍

    2003-01-01

    Using the method of Singular Spectrum Analysis (SSA), the evolution regularity of tropical cyclones landing in Guangdong are analyzed. The main periods of yearly topical cyclones landing in Guangdong are found at 8 and quasi-3 years, and in the west of Pearl River Mouth are 12 and quasi-2 years to the west ofPearl River Mouth. The northwest Pacific that topical cyclones are generated isdivided into 8 areas, and the Sea-Surface Temperature (SST) in each area is analyzed using SSA. The main periods of NINO-west are 8 and 3 years, and those of the warm pool are 12 and 2 years, respectively. This may be the physical reason for the generation tropical cyclones landing in Guangdong. By combining the Maximum Entropy Method (MEM) with SSA (SSA-MEM), the yearly variation trend of tropical cyclones landing in Guangdong and the Pearl River Mouth are forecast, and theresults are good. The method can be used in operational short-range climate forecast.

  4. Tropical cyclones in a T159 resolution global climate model: comparison with observations and re-analyses

    Science.gov (United States)

    Bengtsson, L.; Hodges, K. I.; Esch, M.

    2007-08-01

    Tropical cyclones have been investigated in a T159 version of the MPI ECHAM5 climate model using a novel technique to diagnose the evolution of the three-dimensional vorticity structure of tropical cyclones, including their full life cycle from weak initial vortices to their possible extra-tropical transition. Results have been compared with re-analyses [the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-yr Re-analysis (ERA40) and Japanese 25 yr re-analysis (JRA25)] and observed tropical storms during the period 1978-1999 for the Northern Hemisphere. There is no indication of any trend in the number or intensity of tropical storms during this period in ECHAM5 or in re-analyses but there are distinct inter-annual variations. The storms simulated by ECHAM5 are realistic both in space and time, but the model and even more so the re-analyses, underestimate the intensities of the most intense storms (in terms of their maximum wind speeds). There is an indication of a response to El Niño-Southern Oscillation (ENSO) with a smaller number of Atlantic storms during El Niño in agreement with previous studies. The global divergence circulation responds to El Niño by setting up a large-scale convergence flow, with the centre over the central Pacific with enhanced subsidence over the tropical Atlantic. At the same time there is an increase in the vertical wind shear in the region of the tropical Atlantic where tropical storms normally develop. There is a good correspondence between the model and ERA40 except that the divergence circulation is somewhat stronger in the model. The model underestimates storms in the Atlantic but tends to overestimate them in the Western Pacific and in the North Indian Ocean. It is suggested that the overestimation of storms in the Pacific by the model is related to an overly strong response to the tropical Pacific sea surface temperature (SST) anomalies. The overestimation in the North Indian Ocean is likely to be due to an over

  5. Advanced In-Furnace NOx Control for Wall and Cyclone-Fired Boilers

    Energy Technology Data Exchange (ETDEWEB)

    Hamid Sarv

    2009-02-28

    A NO{sub x} minimization strategy for coal-burning wall-fired and cyclone boilers was developed that included deep air staging, innovative oxygen use, reburning, and advanced combustion control enhancements. Computational fluid dynamics modeling was applied to refine and select the best arrangements. Pilot-scale tests were conducted by firing an eastern high-volatile bituminous Pittsburgh No.8 coal at 5 million Btu/hr in a facility that was set up with two-level overfire air (OFA) ports. In the wall-fired mode, pulverized coal was burned in a geometrically scaled down version of the B and W DRB-4Z{reg_sign} low-NO{sub x} burner. At a fixed overall excess air level of 17%, NO{sub x} emissions with single-level OFA ports were around 0.32 lb/million Btu at 0.80 burner stoichiometry. Two-level OFA operation lowered the NO{sub x} levels to 0.25 lb/million Btu. Oxygen enrichment in the staged burner reduced the NO{sub x} values to 0.21 lb/million Btu. Oxygen enrichment plus reburning and 2-level OFA operation further curbed the NO{sub x} emissions to 0.19 lb/million Btu or by 41% from conventional air-staged operation with single-level OFA ports. In the cyclone firing arrangement, oxygen enrichment of the cyclone combustor enabled high-temperature and deeply staged operation while maintaining good slag tapping. Firing the Pittsburgh No.8 coal in the optimum arrangement generated 112 ppmv NO{sub x} (0.15 lb/million Btu) and 59 ppmv CO. The optimum emissions results represent 88% NO{sub x} reduction from the uncontrolled operation. Levelized costs for additional NO{sub x} removal by various in-furnace control methods in reference wall-fired or cyclone-fired units already equipped with single-level OFA ports were estimated and compared with figures for SCR systems achieving 0.1 lb NO{sub x}/10{sup 6} Btu. Two-level OFA ports could offer the most economical approach for moderate NO{sub x} control, especially for smaller units. O{sub 2} enrichment in combination with 2-level

  6. Can we predict the frequency of cyclones over Bay of Bengal during October-December?

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    Forecasting cyclone activity in Australian (Nicholls, 1984; 1992) and southern Pacific (Revell and Goulter, 1986) regions with SO (Southern Oscillation) and the influence of El-Nino-Southern Oscillation (ENSO) on Bay of Bengal cyclones (Felton et al...

  7. Wave forecasting and monitoring during very severe cyclone Phailin in the Bay of Bengal.

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B; Remya, P.G.; Harikumar, R.; Sandhya, K.G.; Sirisha, P.; Srinivas, K.; Nagaraju, C.; Nherakkol, A.; KrishnaPrasad, B.; Jeyakumar, C.; Kaviyazhahu, K.; Hithin, N.K.; Kumari, R.; SanilKumar, V.; RameshKumar, M.; Shenoi, S.S.C.; Nayak, S.

    Wave fields, both measured and forecast during the very severe cyclone Phailin, are discussed in this communication. Waves having maximum height of 13.54 m were recorded at Gopalpur, the landfall point of the cyclone. The forecast and observed...

  8. The lowering of sea surface temperature in the east central Arabian sea associated with a cyclone

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Rao, D.P.; Sastry, J.S.

    An analysis of thermal Structure in the East Central Arabian Sea associated with a moderate cyclone is presented. The heat storage and the heat budget components have been computed. Under the influence of the cyclone the Sea Surface Temperature (SST...

  9. The transition from the tropical to the extra-tropical ozone-QBO signature in EMAC-ESCiMo, ERA interim and ozone CCI data

    Science.gov (United States)

    Kerzenmacher, Tobias; Joeckel, Patrick; Braesicke, Peter

    2016-04-01

    The quasi-biennial oscillation (QBO) in the tropical zonal mean stratospheric winds is a major driver of interannual ozone variability in the tropics. The associated ozone variability is clearly seen in the tropics. In addition, it affects the interannual ozone variability in sub-tropical and mid-latitude regions. The QBO influence on ozone in all latitudes can be diagnosed in climate model data (free running or nudged EMAC simulations from the ESCiMo project), reanalysis data (ERA-Interim) and satellite data (ozone CCI). We extract the ozone-QBO signature from the data by using a Fourier filtering technique so that the modelled and observed structures can be compared. Starting from the signal in total column ozone, we construct composite latitude height cross-sections of ozone to reveal the vertical structure of QBO related changes for different phases of the ozone-QBO. We discuss the differences between the modelled (EMAC) and observed (CCI) signatures and compare them to ERA-Interim (a data assimilation system). With this diagnostic we improve our understanding of the physical mechanisms that contribute to ozone variability and how an `ozone change signal' can migrate from the tropics to the extra-tropics. Understanding the main mechanisms involved in this signal transfer lays the foundation for an improved trend detection on decadal time scales.

  10. Satellite-based Tropical Cyclone Monitoring Capabilities

    Science.gov (United States)

    Hawkins, J.; Richardson, K.; Surratt, M.; Yang, S.; Lee, T. F.; Sampson, C. R.; Solbrig, J.; Kuciauskas, A. P.; Miller, S. D.; Kent, J.

    2012-12-01

    Satellite remote sensing capabilities to monitor tropical cyclone (TC) location, structure, and intensity have evolved by utilizing a combination of operational and research and development (R&D) sensors. The microwave imagers from the operational Defense Meteorological Satellite Program [Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS)] form the "base" for structure observations due to their ability to view through upper-level clouds, modest size swaths and ability to capture most storm structure features. The NASA TRMM microwave imager and precipitation radar continue their 15+ yearlong missions in serving the TC warning and research communities. The cessation of NASA's QuikSCAT satellite after more than a decade of service is sorely missed, but India's OceanSat-2 scatterometer is now providing crucial ocean surface wind vectors in addition to the Navy's WindSat ocean surface wind vector retrievals. Another Advanced Scatterometer (ASCAT) onboard EUMETSAT's MetOp-2 satellite is slated for launch soon. Passive microwave imagery has received a much needed boost with the launch of the French/Indian Megha Tropiques imager in September 2011, basically greatly supplementing the very successful NASA TRMM pathfinder with a larger swath and more frequent temporal sampling. While initial data issues have delayed data utilization, current news indicates this data will be available in 2013. Future NASA Global Precipitation Mission (GPM) sensors starting in 2014 will provide enhanced capabilities. Also, the inclusion of the new microwave sounder data from the NPP ATMS (Oct 2011) will assist in mapping TC convective structures. The National Polar orbiting Partnership (NPP) program's VIIRS sensor includes a day night band (DNB) with the capability to view TC cloud structure at night when sufficient lunar illumination exits. Examples highlighting this new capability will be discussed in concert with additional data fusion efforts.

  11. Performance of WRF-ARW model in real-time prediction of Bay of Bengal cyclone `Phailin'

    Science.gov (United States)

    Mandal, M.; Singh, K. S.; Balaji, M.; Mohapatra, M.

    2016-05-01

    This study examines the performance of the Advanced Research core of Weather Research and Forecasting (ARW-WRF) model in prediction of the Bay of Bengal cyclone `Phailin'. The two-way interactive double-nested model at 27 and 9-km resolutions customized at Indian Institute of Technology Kharagpur (IITKGP) is used to predict the storm on real-time basis and five predictions are made with five different initial conditions. The initial and boundary conditions for the model are derived from the Global Forecasting System (GFS) analysis and forecast respectively. The track of storm is well predicted in all the five forecasts. In particular, the forecast with less initial positional error led to more accurate track and landfall prediction. It is observed that the predicted peak intensity and translation speed of the storm depends strongly on initial intensity error, vertical wind shear and vertical distribution of maximum potential vorticity. The trend of intensification and dissipation of the storm is well predicted by the model in terms of central sea level pressure (CSLP). The intensity in terms of maximum surface wind (MSW) is under-predicted by the model and it is suggested that the MSW estimated from predicted pressure drop may be used as prediction guideline. The storm intensified rapidly during its passage over the high Tropical Cyclone Heat Potential zone and is reasonably well predicted by the model. Though the magnitude of the precipitation is not well predicted, distribution of precipitation is fairly well predicted by the model. The track and intensity of the storm predicted by the customized WRF-ARW is better than that of other NWP models. The landfall (time and position) is also better predicted by the model compared to other NWP models if initialized at cyclonic storm stage. The results indicate that the customized model have good potential for real-time prediction of Bay of Bengal cyclones and encourage further investigation with larger number of cyclones.

  12. A review of flow modeling for dense medium cyclones

    Energy Technology Data Exchange (ETDEWEB)

    M. Narasimha; M.S. Brennan; P.N. Holtham [Tata Steel, Jamshedpur (India). R& amp; D Division

    2006-06-15

    A critical assessment is presented for the existing fluid flow models used for dense medium cyclones (DMCs) and hydrocyclones. As the present discussion indicates, the understanding of dense medium cyclone flow is still far from the complete. However, its similarity to the hydrocyclone provides a basis for improved understanding of fluid flow in DMCs. The complexity of fluid flow in DMCs is basically due to the existence of medium as well as the dominance of turbulent particle size and density effects on separation. Both the theoretical and experimental analysis is done with respect to two-phase motions and solid phase flow in hydrocyclones or DMCs. A detailed discussion is presented on the empirical, semiempirical, and the numerical models based upon both the vorticity-stream function approach and Navier-Stokes equations in their primitive variables and in cylindrical coordinates available in literature. The existing equations describing turbulence and multiphase flows in cyclone are also critically reviewed.

  13. Impact of Vertical Wind Shear on Tropical Cyclone Rainfall

    Science.gov (United States)

    Cecil, Dan; Marchok, Tim

    2014-01-01

    While tropical cyclone rainfall has a large axisymmetric component, previous observational and theoretical studies have shown that environmental vertical wind shear leads to an asymmetric component of the vertical motion and precipitation fields. Composites consistently depict a precipitation enhancement downshear and also cyclonically downwind from the downshear direction. For consistence with much of the literature and with Northern Hemisphere observations, this is subsequently referred to as "Downshear-Left". Stronger shear magnitudes are associated with greater amplitude precipitation asymmetries. Recent work has reinforced the prior findings, and explored details of the response of the precipitation and kinematic fields to environmental vertical wind shear. Much of this research has focused on tropical cyclones away from land, to limit the influence of other processes that might distort the signal related to vertical wind shear. Recent evidence does suggest vertical wind shear can also play a major role in precipitation asymmetries during and after landfall.

  14. Demonstration of coal reburning for cyclone boiler NO{sub x} control. Appendix, Book 1

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    Based on the industry need for a pilot-scale cyclone boiler simulator, Babcock Wilcox (B&W) designed, fabricated, and installed such a facility at its Alliance Research Center (ARC) in 1985. The project involved conversion of an existing pulverized coal-fired facility to be cyclone-firing capable. Additionally, convective section tube banks were installed in the upper furnace in order to simulate a typical boiler convection pass. The small boiler simulator (SBS) is designed to simulate most fireside aspects of full-size utility boilers such as combustion and flue gas emissions characteristics, fireside deposition, etc. Prior to the design of the pilot-scale cyclone boiler simulator, the various cyclone boiler types were reviewed in order to identify the inherent cyclone boiler design characteristics which are applicable to the majority of these boilers. The cyclone boiler characteristics that were reviewed include NO{sub x} emissions, furnace exit gas temperature (FEGT) carbon loss, and total furnace residence time. Previous pilot-scale cyclone-fired furnace experience identified the following concerns: (1) Operability of a small cyclone furnace (e.g., continuous slag tapping capability). (2) The optimum cyclone(s) configuration for the pilot-scale unit. (3) Compatibility of NO{sub x} levels, carbon burnout, cyclone ash carryover to the convection pass, cyclone temperature, furnace residence time, and FEGT.

  15. Rapid assessment tool for tropical cyclone waves and storm surge hazards in Mexico

    Science.gov (United States)

    Appendini, Christian M.; Rosengaus, Michel; Meza-Padilla, Rafael; Camacho-Magaña, Victor

    2017-04-01

    Mexico is under the constant threat of tropical cyclones generated in the Atlantic and the Eastern Pacific oceans. While the National Hurricane Center (NHC) in Miami is responsible for the forecast of tropical cyclones in both basins and providing watch and warning areas information for Mexico, Central America and the Caribbean, they are not responsible to issue waves and storm surge hazards. This work presents a quick assessment tool for waves and storm surge hazards developed under conditions that are common to developing countries: tight budget and time constraints, as well as limited numerical modeling capabilities. The system is based on 3100 synthetic tropical cyclones doing landfall in Mexico. Hydrodynamic and wave models were driven by the synthetic events to create a robust database composed of maximum envelops of wind speed, significant wave height and storm surge for each event. The results were incorporated into a forecast system that uses the NHC advisory to locate the synthetic events passing inside specified radiuses for the present and forecast position of the real event. Using limited computer resources, the system displays the information meeting the search criteria, and the forecaster can select specific events to generate the desired hazard map (i.e. wind, waves, and storm surge) based on the maximum envelop maps. This system was developed in a limited time frame to be operational in 2015 by the Hurricane and Severe Storms Unit of the Mexican National Weather Service, and represents a pilot project for other countries in the region not covered by detailed storm surge and waves forecasts.

  16. Tropical cyclone Pam coastal impact survey in Vanuatu

    Science.gov (United States)

    Fritz, H. M.; Pilarczyk, J.; Kosciuch, T. J.; Hong, I.; Rarai, A.; Harrison, M. J.; Jockley, F. R.; Horton, B.

    2015-12-01

    Severe tropical cyclone Pam (Cat. 5, SSHS) crossed the Vanuatu archipelago with sustained winds of 270 km/h on March 13 and 14, 2015 and made landfall on Erromango. Pam caused the worst natural disaster in Vanuatu's recorded history since severe tropical cyclone Uma in 1987. Eleven fatalities were directly attributed to cyclone Pam and mostly due to lack of shelter from airborne debris. On March 6 Pam formed east of the Santa Cruz Islands and intensified while tracking southward along Vanuatu severely affecting the Shefa and Tafea Provinces. An international storm surge reconnaissance team was deployed to Vanuatu from June 3 to 17, 2015 to complement earlier local surveys. Cyclone Pam struck a remote island archipelago particularly vulnerable to the combined cyclonic multi-hazards encompassing extreme wind gusts, massive rainfall and coastal flooding due to a combination of storm surge and storm wave impacts. The team surveyed coastal villages on Epi, the Shepherd Islands (Tongoa and Mataso), Efate (including Lelepa), Erromango, and Tanna. The survey spanned 320 km parallel to the cyclone track between Epi and Tanna encompassing more than 45 sites including the hardest hit settlements. Coastal flooding profiles were surveyed from the shoreline to the limit of inundation. Maximum coastal flood elevations and overland flow depths were measured based on water marks on buildings, scars on trees, rafted debris and corroborated with eyewitness accounts. We surveyed 91 high water marks with characteristic coastal flood levels in the 3 to 7 m range and composed of storm surge with superimposed storm waves. Inundation distances were mostly limited to a few hundred meters. Coral boulders of more than 1 m diameter were measured on Erromango and sediment samples were collected at key sites across the archipelago. Infrastructure damage on traditional and modern structures was assessed. Eyewitnesses were interviewed at most sites to document the chronology of the wind and

  17. A FUZZY MATHEMATICS EVALUATION OF THE DISASTER BY TROPICAL CYCLONES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, data from Disaster Reduction in China have been used to statistically analyze the disaster by tropical cyclones that occurred from 1979 to 1996 within the area of Guangdong province. By the method of fuzzy subset theory, the conditions of the disaster have been discussed and the evaluation model of the disaster B set up. The index of the disaster of every tropical cyclone have been obtained and divided into five parts. The result shows that the index is almost proportional to the direct economic losses, so this model is reasonable.

  18. Western North Pacific tropical cyclone wind structure and structure changes

    OpenAIRE

    Fisher, Michael Robert.

    1996-01-01

    Subjective and objective analyses of near-surface winds are utilized to estimate tropical cyclone (TC) size over a region of the western North Pacific. An empirical outer wind profile assuming partial conservation of angular momentum is utilized to determine the radial extent of cyclonic winds, which may be defined as the TC size in four categories. The first method uses the radii of either 3O-kt or 35-kt wind in the Joint Typhoon Warning Center (JTWC) warnings during 1989-1994 to estimate th...

  19. A Probabilistic Rain Diagnostic Model Based on Cyclone Statistical Analysis

    OpenAIRE

    Iordanidou, V.; A. G. Koutroulis; I. K. Tsanis

    2014-01-01

    Data from a dense network of 69 daily precipitation gauges over the island of Crete and cyclone climatological analysis over middle-eastern Mediterranean are combined in a statistical approach to develop a rain diagnostic model. Regarding the dataset, 0.5 × 0.5, 33-year (1979–2011) European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-Interim) is used. The cyclone tracks and their characteristics are identified with the aid of Melbourne University algorithm (MS scheme). T...

  20. Studying temperature and dynamical variations in the extratropical boreal atmosphere in the 2012-2013 winter

    Science.gov (United States)

    Vargin, Pavel; Medvedeva, Irina

    A major Sudden Stratospheric Warming (SSW) event in early January 2013 led to a large increase in the polar stratospheric temperature (up to 60 K at 44 km height), zonal circulation reversal, split of the stratospheric polar vortex (wavenumber 2 type of SSW), and effected temperature and dynamics of the mesosphere - lower thermosphere. We analyzed the SSW-related variations in thermo-dynamical parameters of the atmosphere within a height range from the troposphere to the lower thermosphere, using reanalysis data and data of ground-based spectrometric and satellite observations. Wave activity in the extratropical troposphere and stratosphere was studied using calculated three-day means of the three-dimensional Plumb fluxes. We revealed amplification in activity of planetary waves propagating from the troposphere to the stratosphere over Eastern Siberia - China two weeks prior to that SSW. The eastward propagating Rossby wave-trains observed in the upper troposphere one week before the SSW might have contributed to enhancement of the tropospheric anticyclone over the north-eastern Atlantic that, in turn, led to the splitting of the stratospheric polar vortex during the SSW. To investigate the SSW manifestations in the middle and upper atmosphere over Eastern Siberia, the data of ground-based spectrographic measurements of the OH (834.0 nm, band (6-2)) and O2 (864.5 nm, band (0-1)) emissions obtained at the Geophysical Observatory of the Institute of Solar-Terrestrial Physics (52N, 103E, near Irkutsk) and MLS Aura satellite data were used. An increase in the activity of planetary waves in the 2nd half of November and December 2012 was revealed. During the SSW evolution, an increase in temperature of the stratosphere ( 70 K at 10 hPa) was accompanied by mesospheric cooling which was observed in a narrow layer ( 50 K at 0.01 hPa). In late December - early January, there was significant increase of intensities of OH and O2 emissions originating at the mesosphere and low

  1. The 1985/86 Intraseasonal Oscillation and the Role of the Extratropics.

    Science.gov (United States)

    Hsu, Huang-Hsiung; Hoskins, Brian J.; Jin, Fei-Fei

    1990-04-01

    studies and new numerical model experiments. It describes a mixture of eastward propagation and the flaring of stationary features of tropical convection. However, it does not describe an oscillation. It is possible that equatorial Kelvin waves of very small magnitude do play a role in making such an oscillation possible and that the variable magnitude and period of the oscillation depend on the match of the extratropical structures with the Kelvin wave.

  2. The Role of Interacting Cyclones in Modifying Tropical Cyclone Landfall Threat: Fujiwhara vs. enhanced Beta drift?

    Science.gov (United States)

    Hart, R. E.

    2013-12-01

    The recent impacts of tropical cyclones (TCs) Irene and Sandy have brought to the forefront the question of the true return period of landfalls in that region. Given the relatively short period of record of observations, those seeking robust return estimates often generate stochastic event sets. While the details of methods for generating those sets are generally not published (with an exception being Emanuel 2006), presentations have suggested that each member (TC event) of a stochastic set does not impact other TC members. Such an approach has the benefit of relative simplicity as well as rapidity of production, as each TC member can be produced without concern about simultaneous TCs in the basin. Given most real-world TCs are separated by several days or more, and distances of 2000km or more, this approach is seemingly well-founded for the majority of TC climatology. Yet, there have been many examples of TC-TC Fujiwhara interaction across the globe. While the interaction is much more common in the western Pacific, it is not unheard of in the Atlantic - with Connie and Diane in 1955 as two examples of such interaction but largely away from land. Further, the northeast U.S. coast can be threatened through such TC-TC interactions. The historic 1893 New York City Hurricane took an unusual NNW track (and landfall location) possibly as a consequence of interaction with one if not two additional nearby TCs. Numerical model (WRF) simulations of this case revealed exceptional difficulty in track prediction, illustrating further the complexity of the interaction. Interaction is not necessarily limited to another TC. Occasionally, a TC will interact with an occluded cold-core cyclone, which can then take the TC on a highly unusual track. Such interactions by their nature occur most often early or late in the TC season. Examples of TC-nonTC interaction include the 1938 New England Hurricane, Hurricane Hazel from 1950, and most recently, Hurricane Sandy, all of which had

  3. The sensitivity of characteristics of cyclone activity to identification procedures in tracking algorithms

    Directory of Open Access Journals (Sweden)

    Irina Rudeva

    2014-12-01

    Full Text Available The IMILAST project (‘Intercomparison of Mid-Latitude Storm Diagnostics’ was set up to compare low-level cyclone climatologies derived from a number of objective identification algorithms. This paper is a contribution to that effort where we determine the sensitivity of three key aspects of Northern Hemisphere cyclone behaviour [namely the number of cyclones, their intensity (defined here in terms of the central pressure and their deepening rates] to specific features in the automatic cyclone identification. The sensitivity is assessed with respect to three such features which may be thought to influence the ultimate climatology produced (namely performance in areas of complicated orography, time of the detection of a cyclone, and the representation of rapidly propagating cyclones. We make use of 13 tracking methods in this analysis. We find that the filtering of cyclones in regions where the topography exceeds 1500 m can significantly change the total number of cyclones detected by a scheme, but has little impact on the cyclone intensity distribution. More dramatically, late identification of cyclones (simulated by the truncation of the first 12 hours of cyclone life cycle leads to a large reduction in cyclone numbers over the both continents and oceans (up to 80 and 40%, respectively. Finally, the potential splitting of the trajectories at times of the fastest propagation has a negligible climatological effect on geographical distribution of cyclone numbers. Overall, it has been found that the averaged deepening rates and averaged cyclone central pressure are rather insensitive to the specifics of the tracking procedure, being more sensitive to the data set used (as shown in previous studies and the geographical location of a cyclone.

  4. Steady-state aerosol distributions in the extra-tropical, lower stratosphere and the processes that maintain them

    Directory of Open Access Journals (Sweden)

    J. C. Wilson

    2008-02-01

    Full Text Available Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and the sedimentation of particles in the extra-tropical overworld maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. Exchange with the troposphere is important in understanding aerosol evolution there. Size distributions of volcanically perturbed aerosol are included to distinguish between volcanic and non-volcanic conditions. This analysis suggests that model failures to correctly predict OCS and aerosol properties below 20 km in the Northern Hemisphere extra tropics result from inadequate descriptions of atmospheric circulation.

  5. Steady-state aerosol distributions in the extra-tropical, lower stratosphere and the processes that maintain them

    Directory of Open Access Journals (Sweden)

    J. C. Wilson

    2008-11-01

    Full Text Available Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and sedimentation of particles in the extra-tropical overworld north of 45 N are found to maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. Exchange with the troposphere is important in understanding aerosol evolution there. Size distributions of volcanically perturbed aerosol are included to distinguish between volcanic and non-volcanic conditions. This analysis suggests that model failures to correctly predict OCS and aerosol properties below 20 km in the Northern Hemisphere extra tropics result from inadequate descriptions of atmospheric circulation.

  6. Estimates of Two-Phase Flow Parameters in the Cyclone Chamber

    Directory of Open Access Journals (Sweden)

    Razva Aleksandr

    2016-01-01

    Full Text Available It provides analysis of methods for assessing circumferential speeds distribution of pressure in the cyclone chamber. It is shown that for cylindrical chambers of less than two diameters and the inlet section of at least 0.1 square cross section the maximum peripheral speed and rate distributions circumferential speeds along the current line is not changed. Analysis of the distribution shows that the concentration of small particles that are typical for gas dedusting systems have a significant impact on the distribution of pressure, vacuum and on the axis of the absolute value decreases toward dust of output section unlike the swirl chambers fuel combustion.

  7. Experimental Studies on Swirling Gas—Particle Flows in a Spouting —Cyclone Combustor

    Institute of Scientific and Technical Information of China (English)

    L.X.Zhou; B.Zhou; 等

    1992-01-01

    The gas and particle time-averaged velocity and RMS fluctuation velocity of swirling gas-particle flows in a spouting-cyclone combustor were maesured by a hot-ball probe and a conventional LDV system.The results show large velocity slip between the two phases both in tangential and axial directions and high noisotropic turbulence of the two phases were also observed which is favorable to coal combustion.the particle RMS flutuation velocity is higher than the gas RMS fluctuation velocity only in some regions of the flow field.

  8. A SIMULATION STUDY OF THE INFLUENCE OF LAND FRICTION ON LANDFALL TROPICAL CYCLONE TRACK AND INTENSITY

    Institute of Scientific and Technical Information of China (English)

    YUAN Jin-nan; HUANG Yan-yan; LIU Chun-xia; WAN Qi-lin

    2008-01-01

    A quasi-geostrophic barotropic vorticity equation model is used to simulate the influences of topographic forcing and land friction on landfall tropical cyclone track and intensity. The simulation results show that tropical cyclone track may have sudden deflection when the action of topographic friction dissipation is considered, and sudden deflection of the track is easy to happen and sudden change of tropical cyclone intensity is not clear when the intensity of tropical cyclone is weak and the land friction is strong.The land friction may be an important factor that causes sudden deflection of tropical cyclone track around landfall.

  9. Syndromic surveillance in Vanuatu since Cyclone Pam: a descriptive study

    Directory of Open Access Journals (Sweden)

    George Worwor

    2016-12-01

    Full Text Available In 2012, Vanuatu designed and implemented a syndromic surveillance system based on the guidelines developed by the Pacific Community and the World Health Organization to provide early warning of outbreaks and other important public health events. Four core syndromes were endorsed for surveillance: acute fever and rash, prolonged fever, influenza-like illness and acute watery diarrhoea. In March 2015, Vanuatu was struck by Cyclone Pam, after which several important changes and improvements to the country's syndromic surveillance were made. To date, there has been no formal evaluation of whether regular reports are occurring or that core syndromes are being documented. We therefore carried out a descriptive study in the 11 sentinel sites in Vanuatu conducting syndromic surveillance between July and December 2015. There was a total of 53 822 consultations which were higher in the first 13 weeks (n = 29 622 compared with the last 13 weeks (n = 24 200. During the six months, there were no cases of acute fever and rash or prolonged fever. There were cases with influenza-like illness from week 27 to 35, but no case was reported after week 35. Acute watery diarrhoea occurred in one or two cases per week during the whole study period. For these two core syndromes, there were generally more females than males, and about one third were children aged under 5 years. In conclusion, Vanuatu implemented changes to its new syndromic surveillance system from July to December 2015, although laboratory components had not yet been incorporated. The laboratory components are working in 2016 and will be the subject of a further report.

  10. A comparative study on the genesis of North Indian Ocean tropical cyclone Madi (2013) and Atlantic Ocean tropical cyclone Florence (2006)

    Science.gov (United States)

    Rajasree, V. P. M.; Kesarkar, Amit P.; Bhate, Jyoti N.; Singh, Vikas; Umakanth, U.; Varma, T. Harish

    2016-12-01

    A modeling study has been carried out to understand the similarities and differences in the genesis sequence of a Bay of Bengal tropical cyclone Madi (6-13 December 2013) and the Atlantic Ocean tropical cyclone Florence (3-12 September 2006) on the applicability of hypotheses of the marsupial theory of tropical cyclogenesis. We examined the role of the protective pouch and warm core formation during their genesis and intensification phases. We have chosen tropical cyclone Madi and tropical cyclone Florence for our study specifically due to both of these tropical cyclones originated from westward moving parent disturbance embedded in the intertropical convergence zone. Also, the genesis and intensification of tropical cyclone Florence were accompanied by a series of Saharan dust outbreaks. Our results indicated that the dry air intrusion was not a dominant detrimental factor for the genesis of tropical cyclone Madi and showed rapid intensification within the pouch region. However, in the case of the tropical cyclone Florence, the delay in the intensification as a category 1 tropical cyclone from its tropical depression stage was due to entrainment of the dry air into the core of cyclonic vortex up to 700 hPa from above. The results from this study showed that the wave pouch played a most significant role in the vorticity upscale cascade (First hypothesis) and moisture aggregation (Second hypothesis) in pregenesis period of both the tropical cyclones. It also prevented the lateral dry air intrusion (Second hypothesis) from the Saharan Air Layer during the genesis phase of tropical cyclone Florence.

  11. Cyclone Xaver seen by SARAL/AltiKa

    Science.gov (United States)

    Scharroo, Remko; Fenoglio, Luciana; Annunziato, Alessandro

    2014-05-01

    During the first week of December 2013, Cyclone Xaver pounded the coasts and the North Sea. On 6 December, all along the Wadden Sea, the barrier islands along the north of the Netherlands and the northwest of Germany experienced record storm surges. We show a comparison of the storm surge measured by the radar altimeter AltiKa on-board the SARAL satellite and various types of in-situ data and models. Two tide gauges along the German North Sea coast, one in the southern harbour of the island of Helgoland and one on an offshore lighthouse Alte Weser, confirmed that the storm drove sea level to about three meters above the normal tide level. Loading effects during the storm are also detected by the GPS measurements at several tide gauge stations. The altimeter in the mean time shows that the storm surge was noticeable as far as 400 km from the coast. The altimeter measured wind speeds of 20 m/s nearly monotonically throughout the North Sea. An offshore anemometer near the island of Borkum corroborated this value. A buoy near the FINO1 offshore platform measured wave heights of 8 m, matching quite well the measurements from the altimeter, ranging from 6 m near the German coast to 12 m further out into the North Sea. Furthermore we compare the altimeter-derived and in-situ sea level, wave height and wind speed products with outputs from the Operation Circulation and Forecast model of the Bundesamt für Seeschifffahrt und Hydrographie (BSH) and with a global storm surge forecast and inundation model of the Joint Research Centre (JRC) of the European Commission. The Operational circulation model of BSH (BSHcmod) and its component, the surge model (BSHsmod), perform daily predictions for the next 72 hours based on the meteorological model of the Deutsche Wetterdienst (DWD). The JRC Storm Surge Calculation System is a new development that has been established at the JRC in the framework of the Global Disasters Alerts and Coordination System (GDACS). The system uses

  12. Global near-realtime monitoring of Tropical Cyclones Using Weather Satellites

    Science.gov (United States)

    Lee, T.; Hawkins, J.; Turk, F.; Miller, S.; Sampson, C.; Kuciauskas, A.; Richardson, K.; Kent, J.

    2006-12-01

    The Naval Research Laboratory maintains a satellite web portal that monitors global tropical cyclones in every basin on a continuing basis. The portal is used routinely by agencies around the world in forecasting operations and the issuance of warnings. Products from this site are widely redistributed and published frequently in journal articles, seasonal storm summaries, and ongoing World Wide Web discussions. Traditionally, weather satellite reconnaissance of tropical cyclones has depended on the interpretation of visible and infrared imagery. But such methods have limitations. Visible images are not available during the nighttime, and both kinds of imagery often fail to detect important structure, including storm eyes, which are vital for determining the strength and location of tropical systems. Thus, the portal supplements visible and infrared coverage with products from satellite microwave sensors. These sensors penetrate higher clouds to reveal important detail about low-level cloud and precipitation features. The first part of the talk will discuss how these various products can be used together for improved analysis. The second part of talk will present information about tropical cyclone structure. Surface winds from aircraft will be compared to features seen in passive microwave images. We see that low brightness temperature features on 85 GHz images often corresponding to wind maxima near the sea surface. We shall make some inferences about how the observation of specific structures in satellite images can help characterize the wind field when no aircraft data are available. Special attention will be paid to multiple eye walls apparent on satellite images. These are associated with very intense storms which undergo an evolutionary process not observed in weaker systems.

  13. Cyclone life cycle characteristics over the Northern Hemisphere in coupled GCMs

    Energy Technology Data Exchange (ETDEWEB)

    Loeptien, Ulrike; Latif, Mojib [Leibniz-Institut fuer Meereswissenschaften, Kiel (Germany); Zolina, Olga [P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation); University of Bonn, Meteorological Institute, Bonn (Germany); Gulev, Sergey [Leibniz-Institut fuer Meereswissenschaften, Kiel (Germany); P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation); Soloviov, Vladimir [P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation)

    2008-10-15

    Cyclone activity and life cycle are analysed in the coupled GCMs ECHAM5/OM and ECHAM4/OPYC3. First, the results for the present climate (1978-1999) are compared with ERA-40 and NCEP/NCAR reanalyses, showing a drastic improvement in the representation of cyclone activity in ECHAM5/OM compared to ECHAM4/OPYC3. The total number of cyclones, cyclone intensity, propagation velocity and deepening rates are found to be much more realistic in ECHAM5/OM relative to ECHAM4/OPYC3. Then, changes in extra tropical cyclone characteristics are compared between present day climate and future climate under the emission-scenario A1B using ECHAM5/OM. This comparison is performed using the 20-year time slices 1978-1999, 2070-2090 and 2170-2190, which were considered to be representative for the various climate conditions. The total number of cyclones does not undergo significant changes in a warmer climate. However, regional changes in cyclone numbers and frequencies are evident. One example is the Mediterranean region where the number of cyclones in summer increases almost by factor 2. Some noticeable changes are also found in cyclone life cycle characteristics (deepening rate and propagation velocity). Cyclones in the future climate scenario tend to move slower and their deepening rate becomes stronger, while cyclone intensity does not undergo significant change in a warmer climate. Generally, our results do not support the hypothesis of enhanced storminess under future climate conditions. (orig.)

  14. Effects of melting ice sheets and orbital forcing on the early Holocene warming in extratropical Northern Hemisphere

    Science.gov (United States)

    Zhang, Y.; Renssen, H.; Seppä, H.

    2015-11-01

    The early Holocene is a critical period for climate change, as it marked the final transition from the last deglaciation to the relatively warm and stable Holocene. It is characterized by a warming trend that has been registered in numerous proxy records. This climatic warming was accompanied by major adjustments in different climate components, including the decaying of ice sheets in cryosphere, the perturbation of circulation in the ocean, the expansion of vegetation (over the high latitude) in biosphere. Previous studies have analyzed the influence of the demise of the ice sheets and other forcings on climate system. However, the climate response to the forcings together with the internal feedbacks before 9 ka remains not fully comprehended. In this study, we therefore disentangle how these forcings contributed to climate change during the earliest part of Holocene (11.5-7 ka) by employing the LOVECLIM climate model for both equilibrium and transient experiments. The results of our equilibrium experiments for 11.5 ka reveal that the annual mean temperature at the onset of the Holocene was lower than in the preindustrial era in the Northern extratropics, except in Alaska. The magnitude of this cool anomaly varies regionally as a response to varying climate forcings and diverse mechanisms. In eastern N America and NW Europe the temperatures throughout the whole year were 2-5 °C lower than in the preindustrial control, reaching the maximum cooling as here the climate was strongly influenced by the cooling effects of the ice sheets. This cooling of the ice-sheet surface was caused both by the enhanced surface albedo and by the orography of the ice sheets. For Siberia, a small deviation (-0.5-1.5 °C) in summer temperature and 0.5-1.5 °C cooler annual climate compared to the preindustrial run were caused by the counteraction of the high albedo associated with the tundra vegetation which was more southward extended at 11.5 ka than in the preindustrial period and the

  15. Tropical Cyclone Vulnerability Mapping Using Geospatial Techniques: Application to a Coastal Upazila in Bangladesh

    Science.gov (United States)

    Hoque, M. A. A.; Phinn, S. R.; Roelfsema, C. M.; Childs, I.

    2015-12-01

    Cyclones are one of the most catastrophic natural disasters. Globally, many coastal regions are vulnerable to different categories cyclones. In Bangladesh, disasters from tropical cyclones are annual occurrences in coastal areas. The intensity and extent of damage due to tropical cyclones are very high. An appropriate mapping approach is essential for producing detail vulnerability assessments to deliver useful information for reducing the impacts of cyclones on people, property and environment. The present study developed and tested a vulnerability mapping approach for tropical cyclone impacts in Sarankhola upazila a 151 km2 local government area located in coastal Bangladesh. The study applied the approach by integrating remote sensing, field data and multi-criteria evaluation at regional scales covering Bangladesh to tropical cyclones.

  16. Modelling cyclonic eddies in the Delagoa Bight region

    Science.gov (United States)

    Cossa, O.; Pous, S.; Penven, P.; Capet, X.; Reason, C. J. C.

    2016-05-01

    The objective of this study is to document and shed light on the circulation around the Delagoa Bight region in the southern Mozambique Channel using a realistic modelling approach. A simulation including mesoscale forcings at the boundaries of our regional configuration succeeds in reproducing the general circulation in the region as well as the existence of a semi-permanent cyclonic eddy, whose existence is attested by in situ measurements in the Bight. Characterised by a persistent local minimum in SSH located around 26°S-34°E, this cyclonic eddy termed herein the Delagoa Bight lee eddy occurs about 25% of the time with no clear seasonal preference. Poleward moving cyclones, mostly generated further north, occur another 25% of the time in the Bight area. A tracking method applied to eddies generated in Delagoa Bight using model outputs as well as AVISO data confirms the model realism and provides additional statistics. The diameter of the eddy core varies between 61 and 147 km and the average life time exceeds 20 days. Additional model analyses reveal the systematic presence of negative vorticity in the Bight that can organise and form a Delagoa Bight lee eddy depending on the intensity of an intermittent southward flow along the shore and the spatial distribution of surrounding mesoscale features. In addition, the model solution shows other cyclonic eddies generated near Inhambane and eventually travelling through the Bight. Their generation and pathways appears to be linked with large Mozambique Channel rings.

  17. BABCOCK & WILCOX CYCLONE VITRIFICATION TECHNOLOGY FOR CONTAMINATED SOIL

    Science.gov (United States)

    The Babcock & Wilcox 6 million Btu/hr pilot cyclone furnace was successfully used in a 2-yr Superfund Innovative Technology Evaluation (SITE) Emerging Technology project to melt and vitrify an EPA Synthetic Soil Matrix (SSM) spiked with 7,000 ppm lead, 1,000 ppm cadmium, and 1,5...

  18. APPLICATIONS ANALYSIS REPORT: BABCOCK AND WILCOX CYCLONE FURNACE

    Science.gov (United States)

    This document is an evaluation of the performance of the Babcock & Wilcox (B&W) Cyclone Furnace Vitrification Technology and its applicability as a treatment technique for soils contaminated with heavy metals, radionuclides, and organics. oth the technical and economic aspects of...

  19. Dust cyclone research in the 21st century

    Science.gov (United States)

    Research to meet the demand for ever more efficient dust cyclones continues after some eighty years. Recent trends emphasize design optimization through computational fluid dynamics (CFD) and testing design subtleties not modeled by semi-empirical equations. Improvements to current best available ...

  20. Flow in the Inlet Region in Tangential Inlet Cyclones

    NARCIS (Netherlands)

    Peng, W.; Boot, P.J.A.J.; Hoffmann, A.C; Dries, H.W.A.; Kater, J.

    2001-01-01

    In this paper the flow pattern in a tangential inlet cyclone is studied by laser Doppler anemometry, with emphasis on the inlet region. The particular focus is on axial asymmetry in the flow, which was studied by determining radial profiles of the axial and tangential gas velocity components at four

  1. Evaluation of a Heuristic Model for Tropical Cyclone Resilience

    Science.gov (United States)

    2015-01-26

    Riehl 1958; Kimball 4 2006; Riemer and Montgomery 2011), both of which influence the organization of 5 convection and, ultimately, operation of the...On the ability of dry tropical-cyclone-like vortices to withstand 1 vertical shear. J. Atmos. Sci., 61, 114–119. 2 Kimball , S. K., 2006: A modeling

  2. CONVECTIVE HEAT TRANSFER IN CYCLONE DEVICE WITH EXTERNAL GAS RECIRCULATION

    Directory of Open Access Journals (Sweden)

    S. V. Karpov

    2016-01-01

    Full Text Available The article considers the convective heat transfer on the surface of a hollow cylinder or several billets in a cyclone device with the new principle of external gas recirculation. According to this principle, transport of coolant from the lateral surface of the chamber, where the temperature is the highest, in the axial region is being fulfilled due to the pressure drop between the wall and axial areas of cyclonic flow. Dependency analysis of average and local heat transfer coefficients from operational and geometrical parameters has been performed; the generalized similarity equations for the calculation of the latter have been suggested. It is demonstrated that in case of download of a cyclone chamber with several billets, the use of the considered scheme of the external recirculation due to the specific characteristics of aerodynamics practically does not lead to noticeable changes in the intensity of convective heat transfer. Both experimental data and the numerical simulation results obtained with the use of OpenFOAM platform were used in the work. The investigations fulfilled will expand the area of the use of cyclone heating devices.

  3. Reliability of a jacket structure in a tropical cyclone environment

    Energy Technology Data Exchange (ETDEWEB)

    Vandersc