Sample records for classifying tropical cyclones

  1. Tropical Cyclones John, Steve

    E-print Network

    Greenslade, Diana

    Tropical Cyclones John, Steve and Rosita Tropical Cyclone Season 1999--2000 #12;Tropical Cyclones John, Steve and Rosita Tropical Cyclone Season 1999­2000 © Commonwealth of Australia, August 2000 Hotel: Courtesy of WA Newspapers. #12;Tropical Cyclones John, Steve and Rosita 1 Tropical Cyclones John

  2. Classifying Southern Hemisphere extratropical cyclones

    NASA Astrophysics Data System (ADS)

    Catto, Jennifer

    2015-04-01

    There is a wide variety of flavours of extratropical cyclones in the Southern Hemisphere, with differing structures and lifecycles. Previous studies have classified these manually using upper level flow features or satellite data. 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 850hPa relative vorticity. A clustering method applied to large-scale fields from ERA-Interim at the time of cyclone genesis (when the cyclone is first identified), has been used to objectively classify these cyclones in the Southern Hemisphere. This simple method is able to separate the cyclones into classes with quite different development mechanisms and lifecycle characteristics. Some of the classes seem to coincide with previous manual classifications on shorter timescales, showing their utility for climate model evaluation and climate change studies.

  3. Tropical Cyclone Information System

    NASA Technical Reports Server (NTRS)

    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.

  4. Cloudsat tropical cyclone database

    NASA Astrophysics Data System (ADS)

    Tourville, Natalie D.

    CloudSat (CS), the first 94 GHz spaceborne cloud profiling radar (CPR), launched in 2006 to study the vertical distribution of clouds. Not only are CS observations revealing inner vertical cloud details of water and ice globally but CS overpasses of tropical cyclones (TC's) are providing a new and exciting opportunity to study the vertical structure of these storm systems. CS TC observations are providing first time vertical views of TC's and demonstrate a unique way to observe TC structure remotely from space. Since December 2009, CS has intersected every globally named TC (within 1000 km of storm center) for a total of 5,278 unique overpasses of tropical systems (disturbance, tropical depression, tropical storm and hurricane/typhoon/cyclone (HTC)). In conjunction with the Naval Research Laboratory (NRL), each CS TC overpass is processed into a data file containing observational data from the afternoon constellation of satellites (A-TRAIN), Navy's Operational Global Atmospheric Prediction System Model (NOGAPS), European Center for Medium range Weather Forecasting (ECMWF) model and best track storm data. This study will describe the components and statistics of the CS TC database, present case studies of CS TC overpasses with complementary A-TRAIN observations and compare average reflectivity stratifications of TC's across different atmospheric regimes (wind shear, SST, latitude, maximum wind speed and basin). Average reflectivity stratifications reveal that characteristics in each basin vary from year to year and are dependent upon eye overpasses of HTC strength storms and ENSO phase. West Pacific (WPAC) basin storms are generally larger in size (horizontally and vertically) and have greater values of reflectivity at a predefined height than all other basins. Storm structure at higher latitudes expands horizontally. Higher vertical wind shear (? 9.5 m/s) reduces cloud top height (CTH) and the intensity of precipitation cores, especially in HTC strength storms. Average zero and ten dBZ height thresholds confirm WPAC storms loft precipitation sized particles higher into the atmosphere than in other basins. Two CS eye overpasses (32 hours apart) of a weakening Typhoon Nida in 2009 reveal the collapse of precipitation cores, warm core anomaly and upper tropospheric ice water content (IWC) under steady moderate shear conditions.

  5. Black Swan Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    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 spectrum of characteristics in our synthetic database, although no large surge has been recorded historically as only one moderate storm passed by the area. Tampa black swans are identified as those that move northward parallel to the west Florida coast with high intensities and resonant with the Florida-shelf edge waves to generate extreme surges up to 10 m in Tampa Bay. The Arabian Sea area has sea surface temperatures warm enough to support the development of severe TCs, but TC development has been limited by low humidity and high wind shear, and only one recorded TC (super cyclonic storm Gonu in 2007) moved close to the Persian Gulf, making landfall in Oman and Iran. Our analysis shows that black swan TCs can originate within the Persian Gulf and make landfall with high intensities in populous places; extreme surges over 9 m for Abu Dubai and Doha and over 7 m for Dubai are possible. Darwin experienced immense devastation from Cyclone Tracy of 1974, but the damage was mainly due to the strong winds (the surge was only about 1.6 m). Our analysis includes extremely intense black swan TCs that make landfall just south of Darwin, generating surges above 10 m; these results may prompt the city to reconsider its TC risk. We are currently analyzing the join probability of the extreme wind and surge of these black swan TCs to more clearly assess their full damage potentials.

  6. Objective classification of historical tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Chenoweth, Michael

    2007-03-01

    Preinstrumental records of historical tropical cyclone activity require objective methods for accurately categorizing tropical cyclone intensity. Here wind force terms and damage reports from newspaper accounts in the Lesser Antilles and Jamaica for the period 1795-1879 are compared with wind speed estimates calculated from barometric pressure data. A total of 95 separate barometric pressure readings and colocated simultaneous wind force descriptors and wind-induced damage reports are compared. The wind speed estimates from barometric pressure data are taken as the most reliable and serve as a standard to compare against other data. Wind-induced damage reports are used to produce an estimated wind speed range using a modified Fujita scale. Wind force terms are compared with the barometric pressure data to determine if a gale, as used in the contemporary newspapers, is consistent with the modern definition of a gale. Results indicate that the modern definition of a gale (the threshold point separating the classification of a tropical depression from a tropical storm) is equivalent to that in contemporary newspaper accounts. Barometric pressure values are consistent with both reported wind force terms and wind damage on land when the location, speed and direction of movement of the tropical cyclone are determined. Damage reports and derived wind force estimates are consistent with other published results. Biases in ships' logbooks are confirmed and wind force terms of gale strength or greater are identified. These results offer a bridge between the earlier noninstrumental records of tropical cyclones and modern records thereby offering a method of consistently classifying storms in the Caribbean region into tropical depressions, tropical storms, nonmajor and major hurricanes.

  7. APR-2 Tropical Cyclone Observations

    NASA Technical Reports Server (NTRS)

    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.

  8. Tropical Cyclone Report Hurricane Irene

    E-print Network

    Tropical Cyclone Report Hurricane Irene (AL092011) 21-28 August 2011 Lixion A. Avila and John Cangialosi National Hurricane Center 14 December 2011 Updated 19 December 2011 to correct landfall pressure as a category 3 hurricane (on the Saffir-Simpson Hurricane Wind Scale) but gradually weakened after crossing

  9. Objective classification of historical tropical cyclone intensity

    Microsoft Academic Search

    Michael Chenoweth

    2007-01-01

    Preinstrumental records of historical tropical cyclone activity require objective methods for accurately categorizing tropical cyclone intensity. Here wind force terms and damage reports from newspaper accounts in the Lesser Antilles and Jamaica for the period 1795-1879 are compared with wind speed estimates calculated from barometric pressure data. A total of 95 separate barometric pressure readings and colocated simultaneous wind force

  10. Objective classification of historical tropical cyclone intensity

    Microsoft Academic Search

    Michael Chenoweth

    2007-01-01

    Preinstrumental records of historical tropical cyclone activity require objective methods for accurately categorizing tropical cyclone intensity. Here wind force terms and damage reports from newspaper accounts in the Lesser Antilles and Jamaica for the period 1795–1879 are compared with wind speed estimates calculated from barometric pressure data. A total of 95 separate barometric pressure readings and colocated simultaneous wind force

  11. The Distribution of Annual Tropical Cyclone Frequency

    Microsoft Academic Search

    H. C. S. Thom

    1960-01-01

    In preparation for studying and fitting tropical cyclone frequency distributions certain time trends in the climatological series are tested statistically and explanations of their possible cause proposed. The annual frequency of tropical cyclones and hurricanes is hypo- thesized to be a rare-event type of series. On the basis of physical and statistical principles it is shown how the Poisson and

  12. LCSs in tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Rutherford, B.; Montgomery, M. T.

    2011-12-01

    The formation of tropical cyclones in the Atlantic most often occurs at the intersection of the wave trough axis of a westward propagating African easterly wave and the wave critical latitude. Viewed in a moving reference frame with the wave, a cat's eye region of cyclonic recirculation can be seen in streamlines prior to genesis. The cat's eye recirculation region has little strain deformation and its center serves as the focal point for aggregation of convectively generated vertical vorticity. Air inside the cat's eye is repeatedly moistened by convection and is protected from the lateral intrusion of dry air. Since the flow is inherently time-dependent, we contrast the time-dependent structures with Eulerian structures of the wave-relative frame. Time-dependence complicates the kinematic structure of the recirculation region as air masses from the outer environment are allowed to interact with the interior of the cat's eye. LCSs show different boundaries of the cat's eye than the streamlines in the wave-relative frame. These LCSs are particularly important for showing the pathways of air masses that interact with the developing vortex, as moist air promotes development by supporting deep convection, while interaction with dry air impedes development. We primarily use FTLEs to locate the LCSs, and show the role of LCSs in both developing and non-developing storms. In addition, we discuss how the vertical coherence of LCSs is important for resisting the effects of vertical wind shear.

  13. Tropical Cyclone Report: Hurricane Isabel

    NSDL National Science Digital Library

    This detailed description of Hurricane Isabel, a long-lived Cape Verde hurricane that reached Category 5 status on the Saffir-Simpson Hurricane Scale, contains a synoptic history, meteorological statistics, casualty and damage statistics, and a forecast and warning critique. The storm made landfall near Drum Inlet on the Outer Banks of North Carolina as a category 2 hurricane and is considered to be one of the most significant tropical cyclones to affect portions of northeastern North Carolina and east-central Virginia since Hurricane Hazel in 1954 and the Chesapeake-Potomac Hurricane of 1933. Voluminous charts include best track, selected ship reports, selected surface observations, and rainfall. A warnings chart is also included along with a best track map.

  14. Tropical cyclone-ocea~ interactions Isaac Ginis

    E-print Network

    Rhode Island, University of

    Hurricane Andrew in 1992 exceeded 60 with nearly $30 billion damage. Tropical cyclone modeling efforts over of hurricane track predictions over the last 30 years, in contrast there has been no perceptible improvement

  15. Projected increase in tropical cyclones near Hawaii

    NASA Astrophysics Data System (ADS)

    Murakami, Hiroyuki; Wang, Bin; Li, Tim; Kitoh, Akio

    2013-08-01

    Projections of the potential impacts of global warming on regional tropical cyclone activity are challenging owing to multiple sources of uncertainty in model physical schemes and different assumptions for future sea surface temperatures. A key factor in projecting climate change is to derive robust signals of future changes in tropical cyclone activity across different model physical schemes and different future patterns in sea surface temperature. A suite of future warming experiments (2075-2099), using a state-of-the-art high-resolution global climate model, robustly predicts an increase in tropical cyclone frequency of occurrence around the Hawaiian Islands. A physically based empirical model analysis reveals that the substantial increase in the likelihood of tropical cyclone frequency is primarily associated with a northwestward shifting of the tropical cyclone track in the open ocean southeast of the islands. Moreover, significant and robust changes in large-scale environmental conditions strengthen in situ tropical cyclone activity in the subtropical central Pacific. These results highlight possible future increases in storm-related socio-economic and ecosystem damage for the Hawaiian Islands.

  16. Tall Precipitation Cells in Tropical Cyclone Eyewalls Are Associated with Tropical Cyclone Intensification

    NASA Technical Reports Server (NTRS)

    Kelley, Owen A.; Stout, John; Halverson, Jeffrey B.

    2004-01-01

    The association between tall precipitation and tropical cyclone intensification may have implications for the difficult task of forecasting the destructive potential of these storms. We propose a novel way to use radar-observed rain height to help predict tropical cyclone intensity. Then, we adapt this technique for use on the much more plentiful data from infrared and microwave instruments.

  17. Mesoscale Interactions in Tropical Cyclone Genesis

    Microsoft Academic Search

    J. Simpson; E. Ritchie; G. J. Holland; J. Halverson; S. Stewart

    1997-01-01

    With the multitude of cloud clusters over tropical oceans, it has been perplexing that so few develop into tropical cyclones. The authors postulate that a major obstacle has been the complexity of scale interactions, particularly those on the mesoscale, which have only recently been observable. While there are well-known climatological requirements, these are by no means sufficient. A major reason

  18. Global view of the upper level outflow patterns associated with tropical cyclone intensity changes during FGGE

    NASA Technical Reports Server (NTRS)

    Chen, L.; Gray, W. M.

    1985-01-01

    The characteristics of the upper tropospheric outflow patterns which occur with tropical cyclone intensification and weakening over all of the global tropical cyclone basins during the year long period of the First GARP Global Experiment (FGGE) are discussed. By intensification is meant the change in the tropical cyclone's maximum wind or central pressure, not the change of the cyclone's outer 1 to 3 deg radius mean wind which we classify as cyclone strength. All the 80 tropical cyclones which existed during the FGGE year are studied. Two-hundred mb wind fields are derived from the analysis of the European Center for Medium Range Weather Forecasting (ECMWF) which makes extensive use of upper tropospheric satellite and aircraft winds. Corresponding satellite cloud pictures from the polar orbiting U.S. Defense Meteorological Satellite Program (DMSP) and other supplementary polar and geostationary satellite data are also used.

  19. On the size distribution of Atlantic tropical cyclones

    E-print Network

    Emanuel, Kerry Andrew

    The size of a tropical cyclone is known to vary considerably across storms, though little is understood about the environmental and internal factors that modulate it. Making use of newly available extended tropical cyclone ...

  20. Modelling Atlantic Basin Tropical Cyclone Storm Tracks

    NASA Astrophysics Data System (ADS)

    Hardisty, F.; Carroll, D.

    2011-12-01

    Two of the most useful data sets for understanding Atlantic Basin tropical cyclones are the HURDAT data set, provided by NOAA, and the Extended Best Track (EBT) data set, provided by Colorado State University. Each has their strengths: the HURDAT is a more complete set of cyclone tracks, while the EBT contains additional radial extent, wind speed, and pressure information for a more limited set of cyclones. We report here on methods that we developed to generate realistic synthetic cyclone tracks using the strengths of each data set. We also report on some novel visualization methods (using HTML5) and cloud computing methods we employed in the research. We hope that this research will lead to more accurate predictions of the number and severity of cyclones for a given season.

  1. Tropical Cyclone Structure Analysis: A MultiSensor Approach

    Microsoft Academic Search

    M. Demaria; K. S. Maclay; J. A. Knaff

    2006-01-01

    Tropical cyclones include many scales, ranging from the individual convective elements (1-10 km) to the upper level outflow that can extend to more than 1000 km from the storm center. At the present time there is no individual sensor that can measure all aspects of tropical cyclones. In this study, a multi-sensor method for diagnosing the tropical cyclone wind field

  2. DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL BELOW AND BEHIND IT. STRAIGHT HORIZONTAL PIPE IS SLIME FEED FROM ROD MILL. PIPE OUT TOP OF CYCLONE AND CURVING AT LOWER RIGHT CARRIED FINELY GROUND SLIME TO FLOTATION CONDITIONER TANK. PIPE NOT VISIBLE OUT BOTTOM OF CYCLONE CONVEYED COARSER SLIME TO BALL MILL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  3. Tropical cyclone rainfall area controlled by relative sea surface temperature.

    PubMed

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-01-01

    Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates. PMID:25761457

  4. The Impact of Tropical Cyclones on the Geomorphic Evolution of Bolivar Peninsula, TX 

    E-print Network

    Hales, Billy

    2012-07-16

    . What contributions do tropical cyclones give toward the evolution of a spit, and do tropical cyclones give the same kinds of impacts? To determine if tropical cyclones have similar impacts, shoreline and volumetric change from four storms impacting...

  5. Observations of Tropical Cyclones With the SSMIS

    Microsoft Academic Search

    Jeffrey D. Hawkins; F. Joseph Turk; Thomas F. Lee; Kim Richardson

    2008-01-01

    Passive microwave (PMW) radiometric observations of tropical cyclones (TCs) from the special sensor microwave imager\\/sounder (SSMIS) continue the legacy monitoring capabilities initiated with the special sensor microwave\\/imager (SSM\\/I) that began in 1987. The SSMIS has the following several important differences that should be factored into applications when compared to SSM\\/I data: 1) channel changes from 85 to 91 GHz result

  6. Cyclone Center: Using Crowdsourcing to Determine Tropical Cyclone Intensity (Invited)

    NASA Astrophysics Data System (ADS)

    Hennon, C. C.; Knapp, K. R.; Schreck, C. J.; Stevens, S. E.; Kossin, J. P.

    2013-12-01

    The strength of tropical cyclones (TCs) is traditionally determined using the sustained maximum wind speed. Because TCs develop and spend most of their lifetime over tropical oceans, it is rare to directly observe a storm well enough to determine its strength accurately. The Dvorak technique was developed in the 1970s and 1980s to address this problem. By determining a number of cloud and structural characteristics from satellite images, a forecaster could now arrive at a reasonable maximum sustained wind without direct observations. However, the Dvorak technique by nature is subjective and it has been shown that trained experts frequently disagree on storm intensities. Furthermore, the application of the rules and constraints of the process has diverged with time across different forecast centers. This has led in several cases to severe disagreements in storm intensities when two or more forecast centers track the same TC. The accumulation of these differences has caused heterogeneous trends in TC intensity to arise at decadal time scales. A global reanalysis of TC intensity is required to resolve these discrepancies, but such an undertaking is unrealistic. Cyclone Center, an Internet crowd sourcing site for TCs, was created to resolve differences in TC intensities and produce a consistent 32-year (1978-2009) record of it. By using a homogeneous satellite dataset (HURSAT) and adapting the Dvorak technique into a set of three or four simple questions, laypersons perform the actions of the expert. User responses are converted into 3-hourly storm intensities. To capitalize on the crowd sourcing approach, at least 10 different users are shown the same image; this allows critical data such as cloud pattern uncertainties and storm metadata (e.g. eye size, center location, cloud pattern) to be collected. Preliminary analyses show that our citizen scientists many times outperform computer classifications in pattern matching and exhibit low bias and mean error when compared to a 'ground truth' set of storms (sampled with aircraft reconnaissance data). However, the intensity data can be noisy; we believe that further refinements in the statistical processing of user responses and the calculation of intensities using cloud top temperature should mitigate this concern and lead to lower errors. Typhoon Ivan (1997) is one of several hundred tropical cyclones that citizen scientists are analyzing

  7. Ocean Barrier Layers’ Effect on Tropical Cyclone Intensification

    SciTech Connect

    Balaguru, Karthik; Chang, P.; Saravanan, R.; Leung, Lai-Yung R.; Xu, Zhao; Li, M.; Hsieh, J.

    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.

  8. Tropical cyclone preparedness and response : opportunities for operations research

    E-print Network

    Murphy, Maurice D

    2008-01-01

    This thesis explores how operations research methods can be applied in the emergency response community by looking at two recent tropical storm disasters; tropical cyclone Yemyin in Pakistan, June 2007 and super typhoon ...

  9. Space options for tropical cyclone hazard mitigation

    NASA Astrophysics Data System (ADS)

    Dicaire, Isabelle; Nakamura, Ryoko; Arikawa, Yoshihisa; Okada, Kazuyuki; Itahashi, Takamasa; Summerer, Leopold

    2015-02-01

    This paper investigates potential space options for mitigating the impact of tropical cyclones on cities and civilians. Ground-based techniques combined with space-based remote sensing instrumentation are presented together with space-borne concepts employing space solar power technology. Two space-borne mitigation options are considered: atmospheric warming based on microwave irradiation and laser-induced cloud seeding based on laser power transfer. Finally technology roadmaps dedicated to the space-borne options are presented, including a detailed discussion on the technological viability and technology readiness level of our proposed systems. Based on these assessments, the space-borne cyclone mitigation options presented in this paper may be established in a quarter of a century.

  10. Detailed structure within a tropical cyclone ``eye''

    NASA Astrophysics Data System (ADS)

    Teshiba, Michihiro; Fujita, Hiroshi; Hashiguchi, Hiroyuki; Shibagaki, Yoshiaki; Yamanaka, Manabu D.; Fukao, Shoichiro

    2005-12-01

    The characteristics of the ``eye'' and eyewall of a Tropical Cyclone (TC) are examined with a wind profiler and upper-soundings around a small island belonging to Japan. There are few observations of wind behavior in the eye of a TC with high time and height resolutions. In the eye of the TC, weak cyclonic wind and updraft formed like a cylinder centered on the TC. The updraft did not form clouds and precipitation because stable and relatively dry air existed in the middle troposphere. There were dry layers above the middle troposphere in the eye, especially in the lower layers on the front side of the TC. Therefore, the rainfall associated with the eyewall was strengthened and developed. This is the first time that the detailed wind behavior in the eye of the TC in the developing and mature stage has been observed.

  11. The impact of climate change on global tropical cyclone damage

    Microsoft Academic Search

    Kerry Emanuel; Shun Chonabayashi; Laura Bakkensen; Robert Mendelsohn

    2012-01-01

    One potential impact from greenhouse-gas emissions is increasing damage from extreme events. Here, we quantify how climate change may affect tropical cyclone damage. We find that future increases in income are likely to double tropical cyclone damage even without climate change. Climate change is predicted to increase the frequency of high-intensity storms in selected ocean basins depending on the climate

  12. Tropical Cyclone Boura on November 17, 2002

    NSDL National Science Digital Library

    Lori Perkins

    2002-11-21

    Tropical Cyclone Boura approaches Madagascar on November 17, 2002. The storm has intensified over night. The rain structure is depicted with 5 different isosurfaces. The first isosurface is grey and depicts areas with 0.5 inches of rain per hour. The second is light blue and reflects 1.0 inches of rain per hour. THe third is green and shows 1.7 inches of rain per hour. The forth is yellow and represents 2.0 inches of rain per hour. The last isosurface is red and shows 2.2 inches or more of rain per hour.

  13. Emergency Department Presentations following Tropical Cyclone Yasi

    PubMed Central

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

    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, 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. Results 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). Discussion 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. PMID:26111010

  14. Coastal flooding by tropical cyclones and sea-level rise.

    PubMed

    Woodruff, Jonathan D; Irish, Jennifer L; Camargo, Suzana J

    2013-12-01

    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. PMID:24305147

  15. Analysis of Tropical Cyclone Tracks in the North Indian Ocean

    NASA Astrophysics Data System (ADS)

    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.

  16. Projecting global tropical cyclone economic damages with validation of tropical cyclone economic damage model

    NASA Astrophysics Data System (ADS)

    Iseri, Y.; Iwasaki, A.; Miyazaki, C.; Kanae, S.

    2014-12-01

    Tropical cyclones (TCs) sometimes cause serious damages to human society and thus possible changes of TC properties in the future have been concerned. In fact, the Fifth Assessment Report (AR5) by IPCC (Intergovernmental Panel on Climate Change) mentions likely increasing in intensity and rain rate of TCs. In addition, future change of socioeconomic condition (e.g. population growth) might worsen TC impacts in the future. Thereby, in this study, we developed regression models to estimate economic damages by TCs (hereafter TC damage model), and employed those models to project TC economic damages under several future climate and socioeconomic scenarios. We developed the TC damage models for each of 4 regions; western North Pacific, North American, North Indian, and Southern Hemisphere. The inputs for TC damage model are tropical cyclone central pressure, populations in the area exposed by tropical cyclone wind, and GDP (Gross Domestic Product) per capita. The TC damage models we firstly developed tended to overestimate very low damages and also underestimate very high damages. Thereby we modified structure of TC damage models to improve model performance, and then executed extensive validation of the model. The modified model presented better performance in estimating very low and high TC damages. After the modification and validation of the model, we determined the structure of TC damage models and projected TC economic damages. The result indicated increase in TC economic damage in global scale, while TC economic damage against world GDP would decrease in the future, which result is consistent with previous study.

  17. Hurricane Earl, September 1, 2010/NOAA Tropical Cyclones

    E-print Network

    Fang, Yuguang "Michael"

    Hurricane Earl, September 1, 2010/NOAA Tropical Cyclones A PREPAREDNESS GUIDE U.S. DEPARTMENT, 6 of which became hurricanes East Pacific Ocean: 15 tropical storms, 8 of which became hurricanes Central Pacific Ocean: 4 tropical storms, 2 of which became hurricanes Over a typical 2-year period, the U

  18. GPM Rain Rates in Tropical Cyclone Pam - Duration: 15 seconds.

    NASA Video Gallery

    NASA-JAXA's GPM Satellite Close-up of Cyclone Pam's Rainfall NASA-JAXA's GPM core satellite captured rain rates in Tropical Cyclone Pam at 03:51 UTC (2:51 p.m. local time) on March 14, 2015. Heavie...

  19. Australian Tropical Cyclone Activity: Interannual Prediction and Climate Change

    NASA Astrophysics Data System (ADS)

    Nicholls, N.

    2014-12-01

    It is 35 years since it was first demonstrated that interannual variations in seasonal Australian region tropical cyclone (TC) activity could be predicted using simple indices of the El Niño - Southern Oscillation (ENSO). That demonstration (Nicholls, 1979), which was surprising and unexpected at the time, relied on only 25 years of data (1950-1975), but its later confirmation eventually led to the introduction of operational seasonal tropical cyclone activity. It is worth examining how well the ENSO-TC relationship has performed, over the period since 1975. Changes in observational technology, and even how a tropical cyclone is defined, have affected the empirical relationships between ENSO and seasonal activity, and ways to overcome this in forecasting seasonal activity will be discussed. Such changes also complicate the investigation of long-term trends in cyclone activity. The early work linked cyclone activity to local sea surface temperature thereby leading to the expectation that global warming would result in an increase in cyclone activity. But studies in the 1990s (eg., Nicholls et al., 1998) suggested that such an increase in activity was not occurring, neither in the Australian region nor elsewhere. Trends in Australian tropical cyclone activity will be discussed, and the confounding influence of factors such as changes in observational technologies will be examined. Nicholls, N. 1979. A possible method for predicting seasonal tropical cyclone activity in the Australian region. Mon. Weath. Rev., 107, 1221-1224 Nicholls, N., Landsea, C., and Gill, J., 1998. Recent trends in Australian region tropical cyclone activity. Meteorology and Atmospheric Physics, 65, 197-205.

  20. Tropical cyclone intensity change. A quantitative forecasting scheme

    NASA Technical Reports Server (NTRS)

    Dropco, K. M.; Gray, W. M.

    1981-01-01

    One to two day future tropical cyclone intensity change from both a composite and an individual case point-of-view are discussed. Tropical cyclones occurring in the Gulf of Mexico during the period 1957-1977 form the primary data source. Weather charts of the NW Atlantic were initially examined, but few differences were found between intensifying and non-intensifying cyclones. A rawinsonde composite analysis detected composite differences in the 200 mb height fields, the 850 mb temperature fields, the 200 mb zonal wind and the vertical shears of the zonal wind. The individual cyclones which make up the composite study were then separately examined using this composite case knowledge. Similar parameter differences were found in a majority of individual cases. A cyclone intensity change forecast scheme was tested against independent storm cases. Correct predictions of intensification or non-intensification could be made approximately 75% of the time.

  1. Inducing Tropical Cyclones to Undergo Brownian Motion

    NASA Astrophysics Data System (ADS)

    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.

  2. Global Ensemble Predictions of 2009's Tropical Cyclones Initialized with an Ensemble Kalman Filter

    E-print Network

    Hamill, Tom

    Laboratory, Global Systems Division, Boulder, Colorado 1st revision, submitted to Monthly Weather summer tropical cyclones (TCs) from two experimental global numerical weather prediction ensemble1 Global Ensemble Predictions of 2009's Tropical Cyclones Initialized with an Ensemble Kalman

  3. Global warming shifts Pacific tropical cyclone location MinHo Kwon,1,3

    E-print Network

    Li, Tim

    Global warming shifts Pacific tropical cyclone location Tim Li,1 MinHo Kwon,1,3 Ming Zhao,3 Jong) is used to investigate the change of tropical cyclone frequency in the North Pacific under global warming, and W. Yu (2010), Global warming shifts Pacific tropical cyclone location, Geophys. Res. Lett., 37, L

  4. Prediction of tropical cyclone genesis using a vortex merger index

    NASA Astrophysics Data System (ADS)

    Venkatesh, T. N.; Mathew, Joseph

    2004-02-01

    We propose a new method for detecting tropical cyclone genesis at an early stage by supposing merger of mesoscale midlevel vortices to be a common precursor event. The merger event serves as a selection mechanism and is a possible explanation of why only a small fraction of cloud clusters which meet the necessary conditions actually develop into tropical cyclones. The detection procedure uses satellite IR images which are available in near real-time. After tests using data for the Bay of Bengal basin for the years 1999-2001, a real-time test was conducted for the post-monsoon 2002 and pre-monsoon 2003 seasons. We found that the method was successful in detecting the formation of tropical cyclones 04B (2002) and 01B (2003) about 48 hours before they reached storm strength, and no storm escaped detection.

  5. Observations of Wind Asymmetries in Atlantic Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Dougherty, E.; Davis, C. A.

    2014-12-01

    Most major cities are located on coastlines, vulnerable to the direct impacts of tropical cyclones. Therefore, it is critical to understand and improve prediction of these storms in order to make communities more resilient. Though hurricane warning systems have improved in recent years, these warnings are insufficient, because they fail to account for an indication of tropical cyclone wind asymmetry, or the radial extent of maximum winds in different locations within the cyclone. This study explored the wind asymmetry (defined by magnitude and orientation) among 337 Atlantic tropical cyclones from 1988-2012, utilizing the National Hurricane Center's (NHC) Extended Best Track Dataset (EBT) and Statistical Hurricane Intensity Prediction Scheme (SHIPS). Asymmetry was defined as the magnitude of the largest difference in the radius of gale-force wind across opposing quadrants, normalized by the average of the four wind radii. The asymmetry orientation pointed along the axis of maximum asymmetry toward the quadrant with the greater gale radius. Relationships between wind asymmetry and various storm characteristics such as geographical location, storm life cycle, intensity, size, storm motion, and vertical wind shear were examined. The magnitude of asymmetry increased in higher latitudes and along coastlines, particularly in smaller storms. Asymmetry was higher at the beginning of a storm's life, possibly owing to a less well-organized structure, and higher at the end of a storm's life, coinciding with an increase in vertical wind shear and translation speed. Results from this study may allow for improved tropical cyclone forecasts and warnings to help protect seaside communities.

  6. Field theoretical prediction of a property of the tropical cyclone

    NASA Astrophysics Data System (ADS)

    Spineanu, F.; Vlad, M.

    2014-01-01

    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 classical 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 coherent structures known in natural systems. Therefore the field theoretical (FT) formulation finds that the cuasi-coherent form of the atmospheric vortex (tropical cyclone) at stationarity is an expression of this particular property. In the present work we examine a strong property of the tropical cyclone, which arises in the FT formulation in a natural way: the equality of the masses of the particles associated to the matter field and respectively to the gauge field in the FT model is translated into the equality between the maximum radial extension of the tropical cyclone and the Rossby radius. For the cases where the FT model is a good approximation we calculate characteristic quantities of the tropical cyclone and find good comparison with observational data.

  7. A statistical analysis of the association between tropical cyclone intensity change and tornado frequency

    NASA Astrophysics Data System (ADS)

    Moore, Todd W.

    2015-05-01

    Tropical cyclones often produce tornadoes that have the potential to compound the injury and fatality counts and the economic losses associated with tropical cyclones. These tornadoes do not occur uniformly through time or across space. Multiple statistical methods were used in this study to analyze the association between tropical cyclone intensity change and tornado frequency. Results indicate that there is an association between the two and that tropical cyclones tend to produce more tornadoes when they are weakening, but the association is weak. Tropical cyclones can also produce a substantial number of tornadoes when they are relatively stable or strengthening.

  8. O the Evolution of Tropical Cyclones

    Microsoft Academic Search

    R. W. James

    1951-01-01

    Hurricane development is identified with a steady change from anticyclonic to cyclonic absolute vorticity.A measure of absolute vorticity, the energy ratio, is introduced, and the structure of a number of hurricanes is discussed with its aid.Simple cyclone-models are devised, and the characteristics of hurricane structure and growth elucidated with them. It is shown that the kinetic energy of a circular

  9. Satellite-observed latent heat release in a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Rodgers, E. B.

    1977-01-01

    The latent heat release (LHR) and the distribution of rainfall rate of a tropical cyclone as it grows from a tropical disturbance to a typhoon were determined from Nimbus 5 Electrically Scanning Microwave Radiometer data. The LHR (calculated over a circular area of 4 deg latitude radius) increased during the development and intensification of the storm from a magnitude of 2.7 x 10 to the fourteenth W (in the disturbance stage) to 8.8 x 10 to the fourteenth W (typhoon stage). The latter value corresponds to a mean rainfall rate of 2.0 mm/h. The more intense the cyclone and the greater the LHR, the greater the percentage contribution of the larger rainfall rates to the LHR. As a cyclone intensifies, the higher rainfall rates tend to concentrate toward the center of the circulation.

  10. Automatic template matching method for tropical cyclone eye fix

    Microsoft Academic Search

    Wong Ka Yan; Yip Chi Lap; Li Ping Wah; Tsang Wai Wan

    2004-01-01

    A time-honored way of finding, or fixing, the center of a tropical cyclone (TC) is to overlay templates of spirals onto a printout of radar or satellite image. Modern methods, however, mostly focus on wind field analysis, or other motion vector techniques. These techniques cannot be applied effectively if the image is sampled infrequently, or when the TC moves fast.

  11. TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 131 (2013)

    E-print Network

    Smith, Roger K.

    2013-01-01

    of the incipient storm, thereby greatly amplifying the local vorticity. It exhibits also a degree of randomness-layer parameterization used in the model. KEY WORDS Tropical cyclone, hurricane, typhoon, spin-up, intensification to success- fully forecast the intensity changes of these deadly storms (e.g., Davis et al. 2008). Further

  12. Atlantic Sea Surface Temperatures and Tropical Cyclone Formation

    Microsoft Academic Search

    Lloyd J. Shapiro; Stanley B. Goldenberg

    1998-01-01

    It has long been accepted that interannual fluctuations in sea surface temperature (SST) in the Atlantic are associated with fluctuations in seasonal Atlantic basin tropical cyclone frequency. To isolate the physical mech- anism responsible for this relationship, a singular value decomposition (SVD) is used to establish the dominant covarying modes of tropospheric wind shear and SST as well as horizontal

  13. Tropical cyclone triggering of sediment discharge in Taiwan

    E-print Network

    Sobel, Adam

    and was the first major tropical cyclone to affect Taiwan after the 1999 Chichi earthquake. The passage debris produced during the Chichi earthquake into the Choshui River. We show that a range of atmospheric on long time- scales (106 ­107 yr) has been understood in terms of relief and mean annual precipitation

  14. Frequently Asked Questions: Hurricanes, Typhoons, and Tropical Cyclones

    NSDL National Science Digital Library

    This collection of basic definitions and answers to questions about hurricanes and tropical cyclones includes how they form, how they are named, how intensities are measured, and how storms are forecast. Historical information, information on myths surrounding these storms, links to sites displaying real-time storm information, and safety tips are also included.

  15. Tropical Cyclone Diurnal Cycle as Observed by TRMM

    NASA Technical Reports Server (NTRS)

    Leppert, Kenneth D., II; Cecil, D. J.

    2015-01-01

    Using infrared satellite data, previous work has shown a consistent diurnal cycle in the pattern of cold cloud tops around mature tropical cyclones. In particular, an increase in the coverage by cold cloud tops often occurs in the inner core of the storm around the time of sunset and subsequently propagates outward to several hundred kilometers over the course of the following day. This consistent cycle may have important implications for structure and intensity changes of tropical cyclones and the forecasting of such changes. Because infrared satellite measurements are primarily sensitive to cloud top, the goal of this study is to use passive and active microwave measurements from the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) and Precipitation Radar (PR), respectively, to examine and better understand the tropical cyclone diurnal cycle throughout a larger depth of the storm's clouds. The National Hurricane Center's best track dataset was used to extract all PR and TMI pixels within 1000 km of each tropical cyclone that occurred in the Atlantic basin between 1998-2011. Then the data was composited according to radius (100-km bins from 0-1000 km) and local standard time (LST; 3-hr bins). Specifically, PR composites involved finding the percentage of pixels with reflectivity greater than or equal to 20 dBZ at various heights (i.e., 2-14 km in increments of 2 km) as a function of radius and time. The 37- and 85- GHz TMI channels are especially sensitive to scattering by precipitation-sized ice in the mid to upper portions of clouds. Hence, the percentage of 37- and 85-GHz polarization corrected temperatures less than various thresholds were calculated using data from all storms as a function of radius and time. For 37 GHz, thresholds of 260 K, 265 K, 270 K, and 275 K were used, and for 85 GHz, thresholds of 200-270 K in increments of 10 K were utilized. Note that convection forced by the interactions of a tropical cyclone with land (e.g., due to frictional convergence) may disrupt the natural convective cycle of a cyclone. Hence, only data pertaining to storms whose centers were greater than 300 km from land were included in the composites. Early results suggest the presence of a diurnal cycle in the PR composites of all Atlantic basin tropical cyclones from a height of 2-12 km from approximately 0-400 km radius, but the cycle is most apparent above 6 km. At a height of 8 km, there is a peak (minimum) in the percentage of PR pixels greater than or equal to 20 dBZ near 0 (21) LST in the inner core with some indication that this signal propagates outward with time. In contrast, the 37- and 85-GHz composites show little indication of a diurnal cycle at any radii, regardless of the threshold used. Ongoing work with this project will involve sub-setting the composites according to storm intensity to see if the diurnal cycle varies with storm strength. Moderate to strong vertical wind shear often leads to asymmetries in tropical cyclone convection and may disrupt the cyclone's natural diurnal cycle. Therefore, wind shear thresholds will be applied to the composites to determine if the diurnal cycle becomes more apparent in a low shear environment. Finally, other work to be completed will involve developing composites for other tropical cyclone basins, including the East Pacific, Northwest Pacific, South Pacific, and Indian Ocean.

  16. Tropical Cyclone Intensity in Vertical Wind Shear.

    NASA Astrophysics Data System (ADS)

    Wong, Martin L. M.; Chan, Johnny C. L.

    2004-08-01

    The structure and intensity changes of tropical cyclones (TCs) in environmental vertical wind shear (VWS) are investigated in this study using the fifth-generation Pennsylvania State University National Center for Atmospheric Research (PSU NCAR) Mesoscale Model (MM5). Triply nested domains of 36-, 12-, and 4-km resolution are used with fully explicit moisture physics in the 4-km domain. Idealized environments with easterly shears of 2, 4, 6, 8, and 10 m s-1 between 800 and 200 hPa are applied on an f plane. Under small values of VWS (2 and 4 m s-1), the TC intensities are similar to that of the control (CTRL; i.e., no VWS) after initial adjustments. The TCs under 6 and 8 m s-1 of VWS are not as intense, although they do not weaken during the simulation. On the other hand, the TC in 10 m s-1 of VWS weakened significantly.Given the same VWS, the TC intensity is also found to be sensitive to TC size. Experiments with TCs with a smaller radius of 15 m s-1 wind reveal that while the TC in 2 m s-1 of VWS remains as intense as the CTRL, the TC in the 4 m s-1 VWS case weakened significantly to a minimal hurricane by the end of the simulation. A VWS of 6 m s-1 is strong enough to cause dissipation of the TC in 72 h. These results indicate that the size of a TC has to be taken into account in determining the intensity change of a TC in VWS.In the 10 m s-1 VWS case, the average temperature over the lower half of the troposphere within 50 km from the TC surface center is higher than that of the CTRL throughout the simulation. Such a warming, though of a small magnitude, is also observed for a brief period in the upper half of the troposphere before the rapid weakening of the TC and is related to the asymmetry of temperature required for a tilt of the vortex axis. The evolution of the vortex tilt is found to be similar to the dry simulations in previous studies, with the midlevel center (? = 0.525) located mainly in the southeast quadrant of the surface center. A tendency for the midlevel center to rotate about the surface center is also observed. These results support the idea that the resistance to vertical tilt by the mutual rotation between the low-level and midlevel centers is also valid in the moist simulations.It is hypothesized that the secondary circulation and the associated diabatic heating reduce the vertical tilt and the weakening. Condensation heating offsets the anomalous cooling effect due to the anomalous rising motion ahead of the vortex tilt. For small VWS, the vertical motion asymmetry is not strong enough to destroy the complete secondary circulation and the eyewall. As a result, a large temperature asymmetry and the associated vortex tilt cannot develop. Furthermore, there is no entrainment of cool/dry air in the upper troposphere. Therefore, TCs under small shears can be as intense as the CTRL.Large-scale asymmetries in the form of anticyclones found in previous studies are also observed. These asymmetries are apparently related to the change of shears near the TCs. While the shears at outer radii stay roughly constant with time, the shears near the TC centers can have large temporal fluctuations both in magnitude and orientation. This result suggests that the location at which the VWS is estimated in observational studies could be important in determining the relationship between VWS and TC intensity change.


  17. THE DVORAK TROPICAL CYCLONE INTENSITY ESTIMATION TECHNIQUE

    E-print Network

    affected by TCs (commonly called hurricanes, typhoons, or cyclones). The Dvorak technique's practical and AtmosphericAdministration (NOAA), National Hurri- cane Center (NHC; in Miami,Florida),andtheJoint Typhoon and decay. Dvorak and his colleagues derived an empirical meth- od relating TC cloud structures to storm

  18. Clustering of tropical cyclones in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Vitolo, Renato; Stephenson, David; Cook, Ian

    2010-05-01

    We investigate the spatial dependence of and the large-scale atmospheric and climatic effects on the clustering of tropical cyclones in the North Atlantic Ocean. Tropical cyclone tracks from the HURDAT database are examined. We study the transit of tropical cyclones near points belonging to a grid covering the North Atlantic Ocean. Clustering is characterized by the dispersion (ratio of the variance and the mean) of the yearly counts of cyclone transits at distance less than a radius R from the gridpoints. Coherent patches of overdispersion are found for large radii (R>=300km) in the main development region, in the central North Atlantic, off the Mexican coast in the Gulf of Mexico and in the Caribbean sea. Transits of tropical cyclones with intense windspeeds (>60kt) are overdispersed in smaller regions. Patches of overdispersion occur in the central North Atlantic and in a region surrounding the souther coast of Florida, the western coast of Cuba and the coast of Belize. The influence of large-scale atmospheric and climatic processes is analysed by Poisson regression with a time-varying rate that depends on indices for the Atlantic Multidecadal Oscillation (AMO), the North Atlantic Oscillation (NAO) and the Southern Oscillation (SO). A clear-cut signal is found at the largest spatial scales (R>=300km). The AMO has positive effects on the local transit rate in a very large region of the North Atlantic, around the main development region and Caribbean Sea. Positive effects are found for the NAO around Cuba and the Caribbean. Negative (though small) effects are found for the SOI in the Caribbean and the Gulf of Mexico.

  19. Contribution of Tropical Cyclones to the North Pacific Climatological Rainfall as Observed from Satellites

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Adler, Robert F.; Pierce, Harold F.

    1997-01-01

    Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations for an eleven year period. These satellite-derived rainfall amounts are used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the North Pacific Ocean total rainfall during June-November when tropical cyclones are most important. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from passive microwave satellite observations within 444 km radius of the center of those North Pacific tropical cyclones that reached storm stage and greater. These rain rate observations are converted to monthly rainfall amounts and then compared to those for non-tropical cyclone systems. The main results of this study indicate that: 1) tropical cyclones contribute 7% of the rainfall to the entire domain of the North Pacific during the tropical cyclone season and 12%, 3%, and 4% when the study area is limited to, respectively, the western, central, and eastern third of the ocean; 2) the maxima in tropical cyclone rainfall are poleward (5 deg to 10 deg latitude depending on longitude) of the maxima in non-tropical cyclone rainfall; 3) tropical cyclones contribute a maximum of 30% northeast of the Philippine Islands and 40% of the lower Baja California coast; 4) in the western North Pacific, the tropical cyclone rainfall lags the total rainfall by approximately two months and shows seasonal latitudinal variation following the ITCZ; and 5) in general, tropical cyclone rainfall is enhanced during the El Nino years by warm SSTs in the eastern North Pacific and by the monsoon trough in the western and central North Pacific.

  20. Introduction to Tropical Meteorology, 2nd Edition, Chapter 8: Tropical Cyclones

    NSDL National Science Digital Library

    2014-09-14

    Tropical cyclones are the deadliest tropical weather systems. This chapter describes their seasonal and geographic variability and controls, decadal cycles, and history of naming conventions. Tropical cyclogenesis is explored in depth and the core and balance solutions for regions of the cyclone are examined. Intensity is considered in terms of inner-core dynamics, large-scale environmental controls, limits on potential intensity, satellite interpretation techniques, and classification by wind speed. Factors that influence motion are investigated. Extratropical transition is described in terms of structural changes, preceding mechanisms, and impact on high latitudes. Societal impacts and mitigation are also covered.

  1. Toarcian extreme warmth led to tropical cyclone intensification

    NASA Astrophysics Data System (ADS)

    Krencker, François-Nicolas; Bodin, Stéphane; Suan, Guillaume; Heimhofer, Ulrich; Kabiri, Lahcen; Immenhauser, Adrian

    2015-09-01

    Models predict that tropical cyclone intensity should increase on a warming planet. Observing this relationship remains, however, a difficult task since no clear trend is yet emerging from the anthropogenic record. The geological past offers the opportunity to study this relationship by looking at episodes of extreme warmth, such as the Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, ca. 181 Ma). In this study, we document an increase in the occurrence of storm-related deposits during the onset of the T-OAE in the tide-dominated High Atlas Basin of Morocco, associated with a drastic deepening of the mean storm weather wave base. The palaeolatitude of the High Atlas Basin (18° North during the Early Jurassic) rules out winter storms as the driving mechanism behind the formation of these deposits and points to a dramatic intensification of tropical cyclone intensity during the T-OAE global warming. These new results, combined with the previously reported ubiquitous appearance of storm deposits during the T-OAE in tropical seas of the western Tethyan area, support the concept that the globally averaged intensity of tropical cyclones will increase in the coming century due to the anthropogenic climate change.

  2. Coastal Hazard due to Tropical Cyclones in Mexico

    NASA Astrophysics Data System (ADS)

    Silva-Casarin, R.; Mendoza-Baldwin, E.; Marino-Tapia, I.; Enriquez, C.; Ruiz, G.; Escalante-MAncera, E.; Ruíz-Rentería, F.

    2013-05-01

    The Mexican coast is hit every year by at least 3 cyclones and it is affected for nearly 59 hours a year on average; this induces undesirable consequences, such as coastal erosion and flooding. To evaluate the hazard to which the coastal zone is exposes, a historical characterization of atmospheric conditions (surface winds and pressure conditions of the storms), waves (wave heights and their associated wave periods) and flooding levels due to tropical storms for more than 60 years is presented. The atmospheric and wave conditions were evaluated using a modification of the original parametric Hydromet-Rankin Vortex Model by Bretschneider (1990) and Holland (1980) as presented by Silva, et al. (2002). The flooding levels caused by hurricanes were estimated using a two-dimensional, vertically averaged finite volume model to evaluate the storm surge, Posada et al. (2008). The cyclone model was compared to the data series of 29 cyclones recorded by buoys of the National Data Buoy Center-NOAA and some data recorded in shallow waters near Cancun, Mexico and the flooding model was compared with observed data from Cancun, Mexico; both models gave good results. For the extreme analyses of wind, wave heights and maximum flooding levels on the Mexican coasts, maps of the scale and location parameters used in the Weibull cumulative distribution function and numerical results for different return periods are provided. The historical occurrence of tropical storms is also revised as some studies indicate that the average intensity of tropical cyclones is increasing; no definite trends pointing to an increase in storm frequency or intensity were found. What was in fact found is that although there are more cyclones in the Pacific Ocean and these persist longer, the intensity of the cyclones in the Atlantic Ocean is greater affecting. In any case, the strong necessity of avoiding storm induced coastal damage (erosion and flooding) is reflected in numerous works, such as this one, which aim to better manage the coastal area and reduce its vulnerability to hurricanes. References Bretschneider, C.L., 1990. Tropical Cyclones. Handbook of Coastal and Ocean Engineering, Gulf Publishing Co., Vol. 1, 249-370. Holland, G.L., 1980. An analytical model of wind and pressure profiles in hurricanes. Monthly Weather Review, 108, 1212-1218. Posada, G., Silva, R. & de Brye, S. 2008. Three dimensional hydrodynamic model with multiquadtree meshes. American Journal of Environmental Sciences. 4(3): 209-222. Silva, R., Govaere, G., Salles, P., Bautista, G. & Díaz, G. 2002. Oceanographic vulnerability to hurricanes on the Mexican coast. International Conference on Coastal Engineering, pp. 39-51.

  3. Fine resolution simulations of the effect of climate change on tropical cyclones in the South Pacific

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin

    2015-02-01

    Fine-resolution (18 km) regional climate model simulations using the GFDL regional climate model ZETAC are implemented over a South Pacific domain, where the interannual variability of tropical cyclone formation is large. When forced with observed sea surface temperatures and reanalysis boundary conditions, the model is able to give a good simulation of the interannual variation of regions of tropical cyclone formation, with tropical cyclones simulated to form much further east during El Niño years, as observed. An imposed climate-change perturbation is applied to the model, with the resulting simulation indicating that fewer tropical cyclones form in this region in a warmer world. This result appears to be most closely related to increased vertical velocity in the equatorial Pacific, leading to compensating subsidence in the adjacent tropical cyclone formation regions of the South Pacific, thus suppressing tropical cyclone formation.

  4. Statistical Aspects of the North Atlantic Basin Tropical Cyclones: Trends, Natural Variability, and Global Warming

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2007-01-01

    Statistical aspects of the North Atlantic basin tropical cyclones for the interval 1945- 2005 are examined, including the variation of the yearly frequency of occurrence for various subgroups of storms (all tropical cyclones, hurricanes, major hurricanes, U.S. landfalling hurricanes, and category 4/5 hurricanes); the yearly variation of the mean latitude and longitude (genesis location) of all tropical cyclones and hurricanes; and the yearly variation of the mean peak wind speeds, lowest pressures, and durations for all tropical cyclones, hurricanes, and major hurricanes. Also examined is the relationship between inferred trends found in the North Atlantic basin tropical cyclonic activity and natural variability and global warming, the latter described using surface air temperatures from the Armagh Observatory Armagh, Northern Ireland. Lastly, a simple statistical technique is employed to ascertain the expected level of North Atlantic basin tropical cyclonic activity for the upcoming 2007 season.

  5. Condensed water in tropical cyclone “Oliver”, 8 February 1993

    Microsoft Academic Search

    R. F. Pueschel; D. A. Allen; C. Black; S. Faisant; G. V. Ferry; S. D. Howard; J. M. Livingston; J. Redemann; C. E. Sorenson; S. Verma

    1995-01-01

    On February 8, 1993, the NASA DC-8 aircraft profiled from 10,000 to 37,000 feet (3.1–11.3 km) pressure altitude in a stratified section of tropical cyclone “Oliver” over the Coral Sea northeast of Australia. Size, shape and phase of cloud and precipitation particles were measured with a 2-D Greyscale probe. Cloud\\/ precipitation particles changed from liquid to ice as soon as

  6. A New Method for Estimating Tropical Cyclone Wind Speed Probabilities

    Microsoft Academic Search

    Mark Demaria; John A. Knaff; Richard Knabb; Chris Lauer; Charles R. Sampson; Robert T. Demaria

    2009-01-01

    The National Hurricane Center (NHC) Hurricane Probability Program (HPP) was implemented in 1983 to estimate the probability that the center of a tropical cyclone would pass within 60 n mi of a set of specified points out to 72 h. Other than periodic updates of the probability distributions, the HPP remained unchanged through2005.Beginningin2006,theHPPproductswerereplacedbythosefromanewprogramthatestimates probabilities of winds of at least 34,

  7. Reexamination of Tropical Cyclone Wind–Pressure Relationships

    Microsoft Academic Search

    John A. Knaff; Raymond M. Zehr

    2007-01-01

    Tropical cyclone wind-pressure relationships are reexamined using 15 yr of minimum sea level pressure estimates, numerical analysis fields, and best-track intensities. Minimum sea level pressure is estimated from aircraft reconnaissance or measured from dropwindsondes, and maximum wind speeds are interpolated from best-track maximum 1-min wind speed estimates. The aircraft data were collected primarily in the Atlantic but also include eastern

  8. Effect of surface waves on Charnock coefficient under tropical cyclones

    Microsoft Academic Search

    Il-Ju Moon; Isaac Ginis; Tetsu Hara

    2004-01-01

    The dependence of the air-sea momentum flux on surface wave fields is investigated at very high winds under tropical cyclones. A coupled wave-wind model is applied to estimate the momentum flux under ten hurricanes in the western Atlantic Ocean during 1998–2003. The model explicitly calculates the wave-induced stress vector and the total wind stress vector from a given wind speed

  9. Effect of surface waves on Charnock coefficient under tropical cyclones

    Microsoft Academic Search

    Il-Ju Moon; Isaac Ginis; Tetsu Hara

    2004-01-01

    The dependence of the air-sea momentum flux on surface wave fields is investigated at very high winds under tropical cyclones. A coupled wave-wind model is applied to estimate the momentum flux under ten hurricanes in the western Atlantic Ocean during 1998-2003. The model explicitly calculates the wave-induced stress vector and the total wind stress vector from a given wind speed

  10. Hindcasts of Integrated Kinetic Energy in North Atlantic Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Kozar, Michael; Misra, Vasubandhu

    2015-04-01

    Integrated kinetic energy (IKE) is a recently developed metric that evaluates the destructive potential of a tropical cyclone by assessing the size and strength of its wind field. Despite the potential usefulness of the IKE metric, there are few, if any, operational tools that are specifically designed to forecast IKE in real-time. Therefore, a system of artificial neural networks is created to produce deterministic and probabilistic projections of IKE in North Atlantic tropical cyclones out to 72 hours from a series of relevant environmental and storm specific normalized input parameters. In an effort to assess its real-time skill, this IKE forecasting system is run in a mock-operational mode for the 1990 to 2011 North Atlantic hurricane seasons. Hindcasts of IKE are produced in this manner by running the neural networks with hindcasted input parameters from NOAA's second generation Global Ensemble Forecasting System reforecast dataset. Ultimately, the results of the hindcast exercises indicate that the neural network system is capable of skillfully forecasting IKE in an operational setting at a level significantly higher than climatology and persistence. Ultimately, forecasts of IKE from these neural networks could potentially be an asset for operational meteorologists that would complement existing forecast tools in an effort to better assess the damage potential of landfalling tropical cyclones, particularly with regards to storm surge damage.

  11. Satellite-observed latent heat release in a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Rodgers, E. B.

    1976-01-01

    Data from the Nimbus 5 electrically scanning microwave radiometer (ESMR) are used to make calculations of the latent heat release (L.H.R.) and the distribution of rainfall rate in a tropical cyclone as it grows from a tropical disturbance to a typhoon. The L.H.R. (calculated over a circular area of 4 deg latitude radius) increases during the development and intensification of the storm from a magnitude of 2.7 X 10 to the 21st power ergs/s (in the disturbance stage) to 8.8 X 10 to the 21st power ergs (typhoon stage). The latter value corresponds to a mean rainfall rate of 2.0 mm hr/s. The more intense the cyclone and the greater the L.H.R., the greater the percentage contribution of the larger rainfall rates to the L.H.R. In the disturbance stage the percentage contribution of rainfall rates less than or minus 6 mm hr/s is typically 8%; for the typhoon stage, the value is 38%. The distribution of rainfall rate as a function of radial distance from the center indicates that as the cyclone intensifies, the higher rainfall rates tend to concentrate toward the center of the circulation.

  12. Self-Stratification of Tropical Cyclone Outflow. Part II: Implications for Storm Intensification

    E-print Network

    Emanuel, Kerry Andrew

    Tropical cyclones intensify and are maintained by surface enthalpy fluxes that result from the thermodynamics disequilibrium that exists between the tropical oceans and atmosphere. While this general result has been known ...

  13. NASA Sees Heavy Rainfall, Hot Towers in Tropical Cyclone Nathan - Duration: 15 seconds.

    NASA Video Gallery

    NASA-JAXA's Tropical Rainfall Measuring Mission or TRMM satellite showed that the heaviest rainfall occurring in Tropical Cyclone Nathan on March 18 at 0758 UTC (3:58 a.m. EDT) was falling at a rat...

  14. Viewing the top of the cyclone: CALIOP Ice water content in the uppermost layer of tropical cyclones, 2006 - 2011

    NASA Astrophysics Data System (ADS)

    Avery, M. A.; Heymsfield, A.; Young, S.; Deng, M.; Holz, R. E.; Smith, W.; Vaughan, M.

    2012-12-01

    NASA's Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) is ideally suited to viewing the very top of tropical cyclones. CALIOP measures 532 nm backscattered light, at both parallel and perpendicular polarizations. The backscattered signal, with 60 m vertical resolution, provides an accurate measurement of tropical cyclone cloud top heights. Ice water content is parameterized from optical extinction coefficients. Extinction coefficients are retrieved as the 532 nm beam penetrates the cloud deck, until attenuation occurs at an effective optical depth of approximately three. Depolarization provides some insight about particle habit. CALIOP sensitivity to cloud ice water content in the uppermost layer is 0.1 mg/m3, a detection range that includes sub-visible cirrus. Most hurricane or tropical cyclone measurements are focused on the middle and lower regions of storms, but characterization of cyclone interaction with the lowermost stratosphere at the upper storm boundary may be important for determining the total momentum and moisture transport budget. A survey of 5 years of CALIOP observations of the uppermost layer of tropical cyclones is presented, including more detailed analysis of Hurricanes Bill, Karl, and Earl, and Typhoons Bud, Ileana and Choi-wan. For reference, CALIOP observations of cloud top height and ice water content are also compared with MODIS and CloudSat observations during these six tropical cyclones. A surprising amount of cloud ice is to be found between 16 - 19 km, at the very top of these big storms.

  15. Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century

    E-print Network

    Rothman, Daniel

    climate models. Tropical cyclones downscaled from the climate of the period 1950­2005 are compared frequency of events is consistent with increases in a genesis potential index based on monthly mean global. It has been known for at least 60 y that tropical cyclones are driven by surface enthalpy fluxes (1, 2

  16. Analysis of North Atlantic Tropical Cyclone Intensify Change Using Data Mining

    ERIC Educational Resources Information Center

    Tang, Jiang

    2010-01-01

    Tropical cyclones (TC), especially when their intensity reaches hurricane scale, can become a costly natural hazard. Accurate prediction of tropical cyclone intensity is very difficult because of inadequate observations on TC structures, poor understanding of physical processes, coarse model resolution and inaccurate initial conditions, etc. This…

  17. A Global Climate Model based event set for tropical cyclone risk assessment in the West Pacific

    Microsoft Academic Search

    Renato Vitolo; Jane Strachan; Pier Luigi Vidale; David Stephenson; Ian Cook; Shaun Flay; Matthew Foote

    2010-01-01

    We propose a new approach to the creation of a stochastic event set for tropical cyclone risk assessment in West Pacific, for use in the insurance industry in the catastrophe modelling process. The event set is based on both available observational data and a database of tropical cyclones dynamically simulated by a state-of-the-art Global Climate Model. For an initial proof

  18. Mesoscale Simulation of Tropical Cyclones in the South Pacific: Climatology and Interannual Variability

    E-print Network

    Mesoscale Simulation of Tropical Cyclones in the South Pacific: Climatology and Interannual is shown to reproduce a wide range of mesoscale convective systems. Tropical cyclones grow from the most related to mesoscale in- teractions, which also affect TC tracks and the resulting occurrence. 1

  19. 1.4 GLOBAL STUDIES OF TROPICAL CYCLONES USING THE WORLD WIDE LIGHTNING LOCATION NETWORK

    E-print Network

    Thomas, Jeremy N.

    1 1.4 GLOBAL STUDIES OF TROPICAL CYCLONES USING THE WORLD WIDE LIGHTNING LOCATION NETWORK Natalia N. 2008) 1. INTRODUCTION 1 The lightning activity generated by tropical cyclones is not well understood lightning networks. Recent studies have used satellite-based lightning detection and an extended regional

  20. Global tropical cyclone activity: A link to the North Atlantic Oscillation

    Microsoft Academic Search

    James B. Elsner; Bethany Kocher

    2000-01-01

    An index of global tropical cyclone activity (GTCA) is extracted from an interbasin dispersion matrix composed of correlations in the frequency of tropical cyclones among the five principal basins of activity over the period 1966-1998. The extraction is performed using a single-factor common factor analysis model. Factor scores provide the index of GTCA. The time series of factor scores is

  1. Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones? YUMIN MOON AND DAVID S. NOLAN

    E-print Network

    Nolan, David S.

    Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones? YUMIN MOON AND DAVID S that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue

  2. Convective Modes for Significant Severe Thunderstorms in the Contiguous United States. Part III: Tropical Cyclone Tornadoes

    E-print Network

    : Tropical Cyclone Tornadoes ROGER EDWARDS, ANDREW R. DEAN, RICHARD L. THOMPSON, AND BRYAN T. SMITH NWS Storm of the SPC tropical cyclone (TC) tornado records. Distributions of environmental convective parameters, derived from SPC hourly mesoanalysis fields that have been related to supercells and tornadoes

  3. Modeling the physical and biogeochemical response of a marine shelf system to a tropical cyclone

    Microsoft Academic Search

    S. A. Condie; M. Herzfeld; N. Margvelashvili; J. R. Andrewartha

    2009-01-01

    We describe the first use of a fully integrated biogeochemical model to explore the response of a marine shelf system to a tropical cyclone. Ocean currents, nutrients, sediments and plankton dynamics were simulated under conditions representative of Tropical Cyclone Bobby, which traversed the Australian North West Shelf in February 1995. Results show strong upwelling of nutrients and a phytoplankton bloom.

  4. Convective structure in rapidly intensifying tropical cyclones as depicted by passive microwave measurements

    E-print Network

    Nesbitt, Steve

    ) detect emission from liquid hydrometeors whereas higher frequencies (37­85 GHz) measure scatteringConvective structure in rapidly intensifying tropical cyclones as depicted by passive microwave 7 March 2011; published 15 April 2011. [1] Microwave remote sensing of tropical cyclones under

  5. Satellite-observed latent heat release in a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Rodgers, E. B.

    1976-01-01

    Earlier observational estimates of storm latent heat release (LHR) have been made using a moisture budget approach. The present paper summarizes results for the tropical cyclone Nora, using the electrically scanning microwave radiometer (ESMR) on Nimbus 5, on the basis of the theoretical brightness temperature/rainfall rate relationship for an assumed freezing level of 5 km. The LHR of the storm as a function of time for a circular area of radius 4 deg latitude positioned on the circulation center is discussed along with the calculated mean rain rate as a function of distance from the storm center. The contribution of the various magnitudes of rain rates to the total LHR of the storm is examined. It is concluded that the Nimbus 5 ESMR data can be used to determine the LHR characteristics of tropical cyclones and are potentially useful in the monitoring of such storms. The calculations for Typhoon Nora indicate that the LHR for the storm increases as the storm intensifies from a tropical disturbance to a typhoon.

  6. Radio occultation bending angle anomalies during tropical cyclones

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J. K.

    2011-06-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  7. Radio occultation bending angle anomalies during tropical cyclones

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J.

    2011-02-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  8. Impact of sea surface temperature in modulating movement and intensity of tropical cyclones

    Microsoft Academic Search

    M. Mandal; U. C. Mohanty; P. Sinha; M. M. Ali

    2007-01-01

    It is well recognized that sea surface temperature (SST) plays a dominant role in the formation and intensification of tropical\\u000a cyclones. A number of observational\\/empirical studies were conducted at different basins to investigate the influence of SST\\u000a on the intensification of tropical cyclones and in turn, modification in SST by the cyclone itself. Although a few modeling\\u000a studies confirmed the

  9. Climate Response to Tropical Cyclone-Induced Ocean Mixing in an Earth System Model of Intermediate Complexity

    Microsoft Academic Search

    R. L. Sriver; M. E. Mann; M. P. Goes; K. Keller

    2009-01-01

    We introduce a parameterization of ocean mixing by tropical cyclones into an Earth system model of intermediate complexity. The parameterization is based on previously published global budgets of tropical cyclone mixing derived from high-resolution satellite measurements of surface temperature. Under equilibrium conditions, we find tropical cyclones substantially increase global upper ocean heat content consistent with K. Emanuel's heat pump hypothesis.

  10. Upper-tropospheric influences on Western Pacific tropical cyclone intensity change as inferred from satellite ozone observations

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Stout, John

    1989-01-01

    The use of Nimbus-7 TOMS data to diagnose changes in tropical cyclone intensity is demonstrated. The relationship between upper-tropospheric environmental total ozone distribution and intensity for a tropical cyclone case study is examined. The climatological total ozone patterns are used to identify the upper-tropospheric features to differentiate between intensifying and nonintensifying Western Pacific tropical cyclones.

  11. Budget Comparison of Parameterized Microphysical Processes in Tropical Cyclone Simulations

    NASA Astrophysics Data System (ADS)

    Michelson, Sara A.; Bao, Jian-Wen; Grell, Evelyn D.

    2015-04-01

    Despite the fact that microphysics parameterization schemes used in numerical models for tropical cyclone (TC) prediction can be as complex as being capable of resolving the evolution of hydrometeor size spectra, operational centers still cannot computationally afford to run any TC prediction models with spectrum-resolving schemes operationally. To strike an optimal balance between computational cost and physical effect, there is a need to understand what minimal complexity of microphysics parameterizations is required in operational TC prediction models that are run at affordable resolutions. In order to address this need, we have been investigating whether or not the microphysics schemes currently used in NOAA's operational TC models are complex enough to enable us to use these models for high-resolution prediction of tropical cyclones. In this study, we used the Weather Research and Forecasting (WRF) model to investigate the impact of parameterized warm-rain processes in four widely-used bulk microphysics parameterization schemes on the model-simulated tropical cyclone (TC) development. The schemes investigated, ranging from a single-moment simple 3-category scheme to a complex double-moment 6-category scheme, produce different TC intensification rates and average vertical hydrometeor distributions, as well as different accumulated precipitation. By diagnosing the source and sink terms of the hydrometeor budget equations, we found that the differences in the warm-rain production rate, particularly by conversion of cloud water to rain water, contribute significantly to the variations in the frozen hydrometeor production and in the overall latent heat release above the freezing level. These differences in parameterized warm-rain production reflect the differences of the four schemes in the definition of rain droplet size distribution and consequently in spectrum-dependent microphysical processes, such as accretion growth of frozen hydrometeors and their sedimentation. We will show that the hydrometeor budget analysis of the four schemes indicates that the assumed pathways to the production of frozen hydrometeors are quite sensitive to the amount of available super-cooled rain water and, thus, the uncertainties in the parameterized warm-rain processes can affect the intensification and structure of the model-simulated tropical cyclone. Furthermore, we will show that the results from this study strongly suggest that the advantage of double-moment formulations can be overshadowed by the uncertainties in the spectral definition of individual hydrometeor categories and spectrum-dependent microphysical processes.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Trade-off between intensity and frequency of global tropical cyclones

    NASA Astrophysics Data System (ADS)

    Kang, Nam-Young; Elsner, James B.

    2015-07-01

    Global tropical cyclone climate has been investigated with indicators of frequency, intensity and activity. However, a full understanding of global warming's influence on tropical cyclone climate remains elusive because of the incomplete nature of these indicators. Here we form a complete three-dimensional variability space of tropical cyclone climate where the variabilities are continuously linked and find that global ocean warmth best explains the out-of-phase relationship between intensity and frequency of global tropical cyclones. In a year with greater ocean warmth, the tropical troposphere is capped by higher pressure anomaly in the middle and upper troposphere even with higher moist static energy anomaly in the lower troposphere, which is thought to inhibit overall tropical cyclone occurrences but lead to greater intensities. A statistical consequence is the trade-off between intensity and frequency. We calculate an average increase in global tropical cyclone intensity of 1.3 m s-1 over the past 30 years of ocean warming occurring at the expense of 6.1 tropical cyclones worldwide.

  14. The utilization of satellite observed total ozone to predict tropical cyclone recurvature

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Stout, John

    1990-01-01

    The feasibility of using satellite measurements of total ozone to delineate the characteristic upper-tropospheric wave patterns conductive for tropical cyclone recurvature was investigated using measurements by the Nimbus-7 TOMS instrument measurements of total ozone fields were used to delineate the total ozone distribution for the straight-moving, left-curving, and right-curving tropical cyclones. Using these data for 12-h and 24-h forecasts, it is shown that the composite total ozone maps could be used to differentiate the recurving tropical cyclones from nonrecurving systems, suggesting that the majority of the upper-tropospheric waves delineated by total ozone distribution were deep enough to influence the motion of the storms. The left- and the right-recurving tropical cyclones observed during the 12-hr and 24-hr periods had, respectively, higher and lower upper-tropospheric heights downstream than the nonrecurving cyclones.

  15. Sea surface signature of tropical cyclones using microwave remote sensing

    NASA Astrophysics Data System (ADS)

    Kil, Bumjun; Burrage, Derek; Wesson, Joel; Howden, Stephan

    2013-06-01

    Measuring the sea surface during tropical cyclones (TC) is challenging due to severe weather conditions that prevent shipboard measurements and clouds which mask the sea surface for visible satellite sensors. However, sea surface emission in the microwave L-band can penetrate rain and clouds and be measured from space. The European Space Agency (ESA) MIRAS L-band radiometer on the Soil Moisture and Ocean Salinity (SMOS) satellite enables a view of the sea surface from which the effects of tropical cyclones on sea surface emissivity can be measured. The emissivity at these frequencies is a function of sea surface salinity (SSS), sea surface temperature (SST), sea surface roughness, polarization, and angle of emission. If the latter four variables can be estimated, then models of the sea surface emissivity can be used to invert SSS from measured brightness temperature (TB). Actual measured TB from space also has affects due to the ionosphere and troposphere, which have to be compensated for, and components due to the galactic and cosmic background radiation those have to be removed. In this research, we study the relationships between retrieved SSS from MIRAS, and SST and precipitation collected by the NASA TMI sensor from the Tropical Rainfall Measuring Mission (TRMM) satellite during Hurricane Isaac, in August 2012. During the slower movement of the storm, just before landfall on the vicinity of the Louisiana Shelf, higher precipitation amounts were associated with lower SSS and slightly increased SST. This increased trend of SST and lower SSS under regions of high precipitation are indicative of inhibited vertical mixing. The SMOS Level 2 SSS were filtered by a stepwise process with removal of high uncertainty in TB under conditions of strong surface roughness which are known to create noise. The signature of increased SST associated with increasing precipitation was associated with decreased SSS during the storm. Although further research is required, this study shows that there is a TB signal from the sea surface beneath a tropical cyclone that provides information on roughness and salinity.

  16. Recurving Western North Pacific Tropical Cyclones as Precursors to High-Latitude Blocking

    NASA Astrophysics Data System (ADS)

    Archambault, H.; Harr, P.

    2013-12-01

    High-latitude blocking is a subseasonal atmospheric phenomenon that has been linked to a variety of high-impact weather, including flooding rains, heat waves, and cold-air outbreaks. Increasing understanding of the precursors to high-latitude blocking thus is an avenue through which subseasonal forecasting of high-impact weather may be improved. In this study, the hypothesis that recurving tropical cyclones over the western North Pacific favor high-latitude blocking is explored from statistical and dynamical perspectives. This hypothesis is based on the observed tendency for recurving tropical cyclones to induce cyclonic Rossby wave breaking, a mechanism for high-latitude block formation. In this study, a standard blocking index is used in conjunction with a database of recurving tropical cyclones over the western North Pacific to assess the frequency of blocking episodes following recurving tropical cyclones, and, conversely, the frequency of recurving tropical cyclones preceding blocking episodes. In addition, composite analyses are constructed from the 0.5° NCEP/NCAR Climate Forecast System Reanalysis data to establish the dynamical mechanisms and physical processes linking recurving tropical cyclones to the onset of blocking. It is found that blocking tends to occur a wavelength or more downstream from the recurving tropical cyclone within the poleward exit region of an elongated, intensified jet steam, where cyclonic wave breaking is favored. Given the importance of the jet stream in the onset of blocking, this study specifically addresses how characteristics of the phasing between the tropical cyclone outflow and extratropical features influence the structure and intensity of the downstream jet stream.

  17. Impacts of Tropical Cyclones and Accompanying Precipitation on Infectious Diarrhea in Cyclone Landing Areas of Zhejiang Province, China

    PubMed Central

    Deng, Zhengyi; Xun, Huanmiao; Zhou, Maigeng; Jiang, Baofa; Wang, Songwang; Guo, Qing; Wang, Wei; Kang, Ruihua; Wang, Xin; Marley, Gifty; Ma, Wei

    2015-01-01

    Background: Zhejiang Province, located in southeastern China, is frequently hit by tropical cyclones. This study quantified the associations between infectious diarrhea and the seven tropical cyclones that landed in Zhejiang from 2005–2011 to assess the impacts of the accompanying precipitation on the studied diseases. Method: A unidirectional case-crossover study design was used to evaluate the impacts of tropical storms and typhoons on infectious diarrhea. Principal component analysis (PCA) was applied to eliminate multicollinearity. A multivariate logistic regression model was used to estimate the odds ratios (ORs) and the 95% confidence intervals (CIs). Results: For all typhoons studied, the greatest impacts on bacillary dysentery and other infectious diarrhea were identified on lag 6 days (OR = 2.30, 95% CI: 1.81–2.93) and lag 5 days (OR = 3.56, 95% CI: 2.98–4.25), respectively. For all tropical storms, impacts on these diseases were highest on lag 2 days (OR = 2.47, 95% CI: 1.41–4.33) and lag 6 days (OR = 2.46, 95% CI: 1.69–3.56), respectively. The tropical cyclone precipitation was a risk factor for both bacillary dysentery and other infectious diarrhea when daily precipitation reached 25 mm and 50 mm with the largest OR = 3.25 (95% CI: 1.45–7.27) and OR = 3.05 (95% CI: 2.20–4.23), respectively. Conclusions: Both typhoons and tropical storms could contribute to an increase in risk of bacillary dysentery and other infectious diarrhea in Zhejiang. Tropical cyclone precipitation may also be a risk factor for these diseases when it reaches or is above 25 mm and 50 mm, respectively. Public health preventive and intervention measures should consider the adverse health impacts from tropical cyclones. PMID:25622139

  18. An Estimate of the North Atlantic Basin Tropical Cyclone Activity for the 2011 Hurricane Season

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2011-01-01

    Estimates are presented for the expected level of tropical cyclone activity for the 2011 North Atlantic Basin hurricane season. It is anticipated that the frequency of tropical cyclones for the North Atlantic Basin during the 2011 hurricane season will be near to above the post-1995 means. Based on the Poisson distribution of tropical cyclone frequencies for the current more active interval 1995-2010, one computes P(r) = 63.7% for the expected frequency of the number of tropical cyclones during the 2011 hurricane season to be 14 plus or minus 3; P(r) = 62.4% for the expected frequency of the number of hurricanes to be 8 plus or minus 2; P(r) = 79.3% for the expected frequency of the number of major hurricanes to be 3 plus or minus 2; and P(r) = 72.5% for the expected frequency of the number of strikes by a hurricane along the coastline of the United States to be 1 plus or minus 1. Because El Nino is not expected to recur during the 2011 hurricane season, clearly, the possibility exists that these seasonal frequencies could easily be exceeded. Also examined are the effects of the El Nino-Southern Oscillation phase and climatic change (global warming) on tropical cyclone seasonal frequencies, the variation of the seasonal centroid (latitude and longitude) location of tropical cyclone onsets, and the variation of the seasonal peak wind speed and lowest pressure for tropical cyclones.

  19. Cyclone Driven Sediment Loads in a Tropical Mega-River.

    NASA Astrophysics Data System (ADS)

    Darby, Stephen; Leyland, Julian; Hackney, Christopher; Heasley, Eleanore; Kummu, Matti; Lauri, Hannu; Parsons, Daniel; Nicholas, Andrew; Aalto, Rolf; Best, Jim

    2015-04-01

    Understanding the links between environmental change and sediment transport in the mega-rivers that dominate the flux of terrestrial sediment to their deltas and oceans remains a major challenge. Many large river systems display significant seasonality in flow regime, which is affected to a greater or lesser degree by the influence of large tropical storms, which act to increase their variability and thus drive uncertainty in predicting the impacts associated with changes in future flow regimes. Here we demonstrate the significance of tropical storms in driving sediment flux from one of the world's largest rivers, the Mekong, to its delta. Data was collected at Kratie, Cambodia; this being the site of the Mekong's final reliable flow gauging station before the Mekong delta. Suspended sediment fluxes were estimated by calibrating acoustic backscatter returns from an acoustic Doppler current profiler to observed suspended sediment concentrations (SSCs) across a monsoon cycle. The retrieved SSCs were combined with flow velocity estimates to recover the sediment flux. These estimates of flux were then used to build sediment rating curves to predict suspended flux as a function of flow discharge. A hydrological model, VMod, was then used to estimate daily discharge values for the same historical period, but for a scenario in which the effects of tropical storms on the flow regime are isolated. This was achieved by forcing the hydrological model with daily precipitation values that account for precipitation anomalies associated with observed tropical storms. The difference in cumulative sediment transport estimated by combining the two flow discharge scenarios with the constructed sediment rating curves allowed the contribution of tropical storms to the Lower Mekong's suspended sediment transport regime to be isolated. It was found that sediment loads in the Mekong River attenuate downstream from approximately 120 MT in Laos and Thailand to ~80-90 MT in the alluvial floodplain reaches of Cambodia. Furthermore, it is shown that the proportion of flux generated from tropical cyclones increases downstream and dominates (~60%) the flux observed around the confluence of the 3S basin (the Se San, Sre Pok and Se Kong Rivers) which drains the Vietnamese highlands. This implies future changes in cyclone tracks may impact upon sediment delivery to the Mekong delta.

  20. Do Tropical Cyclones Shape Shorebird Habitat Patterns? Biogeoclimatology of Snowy Plovers in Florida

    PubMed Central

    Convertino, Matteo; Elsner, James B.; Muñoz-Carpena, Rafael; Kiker, Gregory A.; Martinez, Christopher J.; Fischer, Richard A.; Linkov, Igor

    2011-01-01

    Background The Gulf coastal ecosystems in Florida are foci of the highest species richness of imperiled shoreline dependent birds in the USA. However environmental processes that affect their macroecological patterns, like occupancy and abundance, are not well unraveled. In Florida the Snowy Plover (Charadrius alexandrinus nivosus) is resident along northern and western white sandy estuarine/ocean beaches and is considered a state-threatened species. Methodology/Principal Findings Here we show that favorable nesting areas along the Florida Gulf coastline are located in regions impacted relatively more frequently by tropical cyclones. The odds of Snowy Plover nesting in these areas during the spring following a tropical cyclone impact are seven times higher compared to the odds during the spring following a season without a cyclone. The only intensity of a tropical cyclone does not appear to be a significant factor affecting breeding populations. Conclusions/Significance Nevertheless a future climate scenario featuring fewer, but more extreme cyclones could result in a decrease in the breeding Snowy Plover population and its breeding range. This is because the spatio-temporal frequency of cyclone events was found to significantly affect nest abundance. Due to the similar geographic range and habitat suitability, and no decrease in nest abundance of other shorebirds in Florida after the cyclone season, our results suggest a common bioclimatic feedback between shorebird abundance and tropical cyclones in breeding areas which are affected by cyclones. PMID:21264268

  1. Changes in Tropical Cyclone Intensity Over the Past 30 Years: A Global and Dynamic Perspective

    NASA Technical Reports Server (NTRS)

    Wu, Liguang; Wang, Bin; Braun, Scott A.

    2006-01-01

    The hurricane season of 2005 was the busiest on record and Hurricane Katrina (2005) is believed to be the costliest hurricane in U. S. history. There are growing concerns regarding whether this increased tropical cyclone activity is a result of global warming, as suggested by Emanuel(2005) and Webster et al. (2005), or just a natural oscillation (Goldenberg et al. 2001). This study examines the changes in tropical cyclone intensity to see what were really responsible for the changes in tropical cyclone activity over the past 30 years. Since the tropical sea surface temperature (SST) warming also leads to the response of atmospheric circulation, which is not solely determined by the local SST warming, this study suggests that it is better to take the tropical cyclone activities in the North Atlantic (NA), western North Pacific (WNP) and eastern North Pacific (ENP) basins as a whole when searching for the influence of the global-scale SST warming on tropical cyclone intensity. Over the past 30 years, as the tropical SST increased by about 0.5 C, the linear trends indicate 6%, 16% and 15% increases in the overall average intensity and lifetime and the annual frequency. Our analysis shows that the increased annual destructiveness of tropical cyclones reported by Emanuel(2005) resulted mainly from the increases in the average lifetime and annual frequency in the NA basin and from the increases in the average intensity and lifetime in the WNP basin, while the annual destructiveness in the ENP basin generally decreased over the past 30 years. The changes in the proportion of intense tropical cyclones reported by Webster et a1 (2005) were due mainly to the fact that increasing tropical cyclones took the tracks that favor for the development of intense tropical cyclones in the NA and WNP basins over the past 30 years. The dynamic influence associated with the tropical SST warming can lead to the impact of global warming on tropical cyclone intensity that may be very different from our current assessments, which were mainly based on the thermodynamic theory of tropical cyclone intensity.

  2. Can the vertical motions in the eyewall of tropical cyclones support persistent UAV flight?

    E-print Network

    Poh, Chung-Kiak

    2014-01-01

    Powered flights in the form of manned or unmanned aerial vehicles (UAVs) have been flying into tropical cyclones to obtain vital atmospheric measurements with flight duration typically lasting between 12 and 36 hours. Convective vertical motion properties of tropical cyclones have previously been studied. This work investigates the possibility to achieve persistent flight by harnessing the generally pervasive updrafts in the eyewall of tropical cyclones. A sailplane UAV capable of vertical take-off and landing (VTOL) is proposed and its flight characteristics simulated. Results suggest that the concept of persistent flight within the eyewall is promising and may be extendable to the rainband regions.

  3. Response of tropical sea surface temperature, precipitation, and tropical cyclone-related variables to changes in global and local forcing

    E-print Network

    Sobel, Adam

    A single-column model is used to estimate the equilibrium response of sea surface temperature (SST), precipitation, and several variables related to tropical cyclone (TC) activity to changes in both local and global forcing. ...

  4. Developing an enhanced tropical cyclone data portal for the Southern Hemisphere and the Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Kuleshov, Yuriy; de Wit, Roald; Atalifo, Terry; Prakash, Bipendra; Waqaicelua, Alipate; Kunitsugu, Masashi; Caroff, Philippe; Chane-Ming, Fabrice

    2013-04-01

    Tropical cyclones are the most extreme weather phenomena which severely impact coastal communities and island nations. There is an ongoing research (i) on accurate analysis of observed trends in tropical cyclone occurrences, and (ii) how tropical cyclone frequency and intensity may change in the future as a result of climate change. Reliable historical records of cyclone activity are vital for this research. The Pacific Australia Climate Change Science and Adaptation Planning (PACCSAP) program is dedicated to help Pacific Island countries and Timor Leste gain a better understanding of how climate change will impact their regions. One of the key PACCSAP projects is focused on developing a tropical cyclone archive, climatology and seasonal prediction for the regions. As part of the project, historical tropical cyclone best track data have been examined and prepared to be subsequently displayed through the enhanced tropical cyclone data portal for the Southern Hemisphere and the Western Pacific Ocean. Data from the Regional Specialised Meteorological Centre (RSMC) Nadi, Fiji and Tropical Cyclone Warning Centres (TCWCs) in Brisbane, Darwin and Wellington for 1969-1970 to 2010-2011 tropical cyclone seasons have been carefully examined. Errors and inconsistencies which have been found during the quality control procedure have been corrected. To produce a consolidated data set for the South Pacific Ocean, best track data from these four centres have been used. Specifically, for 1969-1970 to 1994-1995 tropical cyclone seasons, data from TCWCs in Brisbane, Darwin and Wellington have been used. In 1995, RSMC Nadi, Fiji has been established with responsibilities for issuing tropical cyclone warnings and preparing best track data for the area south of the equator to 25°S, 160°E to 120°W. Consequently, data from RSMC Nadi have been used as a primary source for this area, starting from the 1995-1996 tropical cyclone season. These data have been combined with the data from TCWC Wellington for the area 25°S to 40°S, 160°E to 120°W and with the data from TCWCs in Brisbane and Darwin for the area south of the equator to 37°S, 135°E to 160°E. In addition, tropical cyclone best track data for the North-West Pacific for 1977-2011 seasons prepared at RSMC Tokyo and for the South Indian Ocean for 1969-2011 prepared at RSMC la Réunion have been added to the dataset. As a result, new design of the Southern Hemisphere/Pacific Tropical Cyclone Data Portal (http://www.bom.gov.au/cyclone/history/tracks/) incorporates best track data for the Western Pacific both south and north of the equator and for the South Indian Ocean. The portal has been developed using the OpenLayers web mapping library. Main features of the portal include dynamic map navigation, presenting detailed cyclone information for a selected region in the Southern Hemisphere and North-West Pacific and displaying changes in tropical cyclone intensity over the lifetime of a cyclone. One of the unique features of the portal is its enhanced functionality for spatial and temporal selection for cyclones in selected areas (e.g. economic exclusion zones of the countries). Acknowledgement The research discussed in this paper was conducted through the PACCSAP supported by the AusAID and the Department of Climate Change and Energy Efficiency and delivered by the Bureau of Meteorology and CSIRO. We acknowledge C. Shamsu, D. Duong, P. Lopatecki, W. Banerjee, P. He, P. Wickramasinghe and A. Bauers from the School of Computer Sciences and IT at the Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Australia for their contribution to the development of the portal's functionality on spatial selection.

  5. A satellite observational and numerical study of precipitation characteristics in western North Atlantic tropical cyclones

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Chang, Simon W.; Pierce, Harold F.

    1994-01-01

    Special Sensor Microwave/Imager (SSM/I) observations were used to examine the spatial and temporal changes of the precipitation characteristics of tropical cyclones. SSM/I observations were also combined with the results of a tropical cyclone numerical model to examine the role of inner-core diabatic heating in subsequent intensity changes of tropical cyclones. Included in the SSM/I observations were rainfall characteristics of 18 named western North Atlantic tropical cyclones between 1987 and 1989. The SSM/I rain-rate algorithm that employed the 85-GHz channel provided an analysis of the rain-rate distribution in greater detail. However, the SSM/I algorithm underestimated the rain rates when compared to in situ techniques but appeared to be comparable to the rain rates obtained from other satellite-borne passive microwave radiometers. The analysis of SSM/I observations found that more intense systems had higher rain rates, more latent heat release, and a greater contribution from heavier rain to the total tropical cyclone rainfall. In addition, regions with the heaviest rain rates were found near the center of the most intense tropical cyclones. Observational analysis from SSM/I also revealed that the greatest rain rates in the inner-core regions were found in the right half of fast-moving cyclones, while the heaviest rain rates in slow-moving tropical cyclones were found in the forward half. The combination of SSM/I observations and an interpretation of numerical model simulations revealed that the correlation between changes in the inner core diabetic heating and the subsequent intensity became greater as the tropical cyclones became more intense.

  6. Decadal Trends of Atlantic Basin Tropical Cyclones (1950-1999)

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2001-01-01

    Ten-year moving averages of the seasonal rates for 'named storms,' tropical storms, hurricanes, and major (or intense) hurricanes in the Atlantic basin suggest that the present epoch is one of enhanced activity, marked by seasonal rates typically equal to or above respective long-term median rates. As an example, the 10-year moving average of the seasonal rates for named storms is now higher than for any previous year over the past 50 years, measuring 10.65 in 1994, or 2.65 units higher than its median rate of 8. Also, the 10-year moving average for tropical storms has more than doubled, from 2.15 in 1955 to 4.60 in 1992, with 16 of the past 20 years having a seasonal rate of three or more (the median rate). For hurricanes and major hurricanes, their respective 10-year moving averages turned upward, rising above long-term median rates (5.5 and 2, respectively) in 1992, a response to the abrupt increase in seasonal rates that occurred in 1995. Taken together, the outlook for future hurricane seasons is for all categories of Atlantic basin tropical cyclones to have seasonal rates at levels equal to or above long-term median rates, especially during non-El Nino-related seasons. Only during El Nino-related seasons does it appear likely that seasonal rates might be slightly diminished.

  7. Tropical cyclone genesis over the south China sea Guihua Wang a,, Jilan Su a

    E-print Network

    Chen, .Dake

    strength of a tropical storm or stronger (i.e., typhoon). Globally, the Northwest Pacific, including by tropical cyclones (TCs) with intensity reaching a tropical storm or stronger. It is also an area numbers of TC and typhoon generated in the Available online at www.sciencedirect.com Journal of Marine

  8. Differential leaflet mortality may influence biogeochemical cycling following tropical cyclones.

    PubMed

    Marler, Thomas E; Ferreras, Ulysses

    2014-01-01

    Intensity of tropical cyclones is expected to increase in the coming century, and an improved understanding of their influence on biogeochemical cycles would benefit ecologists and conservationists. We studied the November 2013 Typhoon Haiyan damage to observe that numerous examples of partial leaf necrosis on intact leaves of trees in the Cycadaceae and Arecaceae families resulted, leaving behind a copious amount of arboreal dead leaf material attached to live leaves. The decay process of this form of arboreal litter has not been previously studied. When compared with decay of ground litter or detached litter suspended in the canopy, we predict the decay process of this form of arboreal litter will include increased photooxidation, leaching, and comminution by detritivorous insects and mites; but decreased catabolism of organic molecules by saprophytic organisms. PMID:25083171

  9. Impacts of Different Grades of Tropical Cyclones on Infectious Diarrhea in Guangdong, 2005-2011

    PubMed Central

    Zhang, Ying; Wang, Wei; Wang, Xin; Jiang, Baofa; Ma, Wei

    2015-01-01

    Objective Guangdong province is one of the most vulnerable provinces to tropical cyclones in China. Most prior studies concentrated on the relationship between tropical cyclones and injuries and mortality. This study aimed to explore the impacts of different grades of tropical cyclones on infectious diarrhea incidence in Guangdong province, from 2005 to 2011. Methods Mann-Whitney U test was firstly used to examine if infectious diarrhea were sensitive to tropical cyclone. Then unidirectional 1:1 case-crossover design was performed to quantitatively evaluate the relationship between daily number of infectious diarrhea and tropical cyclone from 2005 to 2011 in Guangdong, China. Principal component analysis (PCA) was applied to eliminate multicollinearity. Multivariate logistic regression model was used to estimate the hazard ratios (HRs) and the 95% confidence intervals (CI). Results There were no significant relationships between tropical cyclone and bacillary dysentery, amebic dysentery, typhoid, and paratyphoid cases. Infectious diarrhea other than cholera, dysentery, typhoid and paratyphoid significantly increased after tropical cyclones. The strongest effect were shown on lag 1 day (HRs = 1.95, 95%CI = 1.22, 3.12) and no lagged effect was detected for tropical depression, tropical storm, severe tropical storm and typhoon, with the largest HRs (95%CI) of 2.16 (95%CI = 1.69, 2.76), 2.43 (95%CI = 1.65, 3.58) and 2.21 (95%CI = 1.65, 2.69), respectively. Among children below 5 years old, the impacts of all grades of tropical cyclones were strongest at lag 0 day. And HRs were 2.67 (95%CI = 1.10, 6.48), 2.49 (95%CI = 1.80, 3.44), 4.89 (95%CI = 2.37, 7.37) and 3.18 (95%CI = 2.10, 4.81), respectively. Conclusion All grades of tropical cyclones could increase risk of other infectious diarrhea. Severe tropical storm has the strongest influence on other infectious diarrhea. The impacts of tropical cyclones on children under 5 years old were higher than total population. PMID:26106882

  10. Tropical cyclone cooling combats region-wide coral bleaching.

    PubMed

    Carrigan, Adam D; Puotinen, Marji

    2014-05-01

    Coral bleaching has become more frequent and widespread as a result of rising sea surface temperature (SST). During a regional scale SST anomaly, reef exposure to thermal stress is patchy in part due to physical factors that reduce SST to provide thermal refuge. Tropical cyclones (TCs - hurricanes, typhoons) can induce temperature drops at spatial scales comparable to that of the SST anomaly itself. Such cyclone cooling can mitigate bleaching across broad areas when well-timed and appropriately located, yet the spatial and temporal prevalence of this phenomenon has not been quantified. Here, satellite SST and historical TC data are used to reconstruct cool wakes (n=46) across the Caribbean during two active TC seasons (2005 and 2010) where high thermal stress was widespread. Upon comparison of these datasets with thermal stress data from Coral Reef Watch and published accounts of bleaching, it is evident that TC cooling reduced thermal stress at a region-wide scale. The results show that during a mass bleaching event, TC cooling reduced thermal stress below critical levels to potentially mitigate bleaching at some reefs, and interrupted natural warming cycles to slow the build-up of thermal stress at others. Furthermore, reconstructed TC wave damage zones suggest that it was rare for more reef area to be damaged by waves than was cooled (only 12% of TCs). Extending the time series back to 1985 (n = 314), we estimate that for the recent period of enhanced TC activity (1995-2010), the annual probability that cooling and thermal stress co-occur is as high as 31% at some reefs. Quantifying such probabilities across the other tropical regions where both coral reefs and TCs exist is vital for improving our understanding of how reef exposure to rising SSTs may vary, and contributes to a basis for targeting reef conservation. PMID:24474700

  11. The probability of tropical cyclone landfalls in Western North Pacific

    NASA Astrophysics Data System (ADS)

    Bonazzi, A.; Bellone, E.; Khare, S.

    2012-04-01

    The Western North Pacific (WNP) is the most active basin in terms of tropical cyclone and typhoon occurrences. The densely populated countries that form the western boundary of WNP basin -- e.g. China, Japan and the Philippines -- are exposed to extreme wind gusts, storm surge and fresh water flooding eventually triggered by Tropical Cyclones (TC) events. Event-based catastrophe models (hereafter cat models) are extensively used by the insurance industry to manage their exposure against low-frequency/high-consequence events such as natural catastrophes. Cat models provide their users with a realistic set of stochastic events that expands the scope of a historical catalogue. Confidence in a cat model ability to extrapolate peril and loss statistics beyond the period covered by observational data requires good agreement between stochastic and historical peril characteristics at shorter return periods. In WNP risk management practitioners are faced with highly uncertain data to base their decisions. Albeit 4 national agencies maintain best track catalogues, data are generally based on satellite imageries with very limited central pressure (CP) and maximum velocity (VMAX) measurements -- regular flight reconnaissance missions stopped in 1987. As a result differences up to 20 knots are found in estimates of VMAX from different agencies as documented in experiment IOP-10 during Typhoon Megi in 2010. In this work we present a comprehensive analysis of CP and VMAX probability distributions at landfall across the WNP basin along a set of 150 gates (100 km coast segments) based on best track catalogues from Japan Meteorological Agency, Joint Typhoon Warning Center, China Meteorological Agency and Hong Meteorological Agency. Landfall distributions are then used to calibrate a random-walk statistical track model. A long simulation of 100,000 years of statistical TC tracks will ultimately constitute the central building block of a basin-wide stochastic catalogue of synthetic TC events fully characterized in terms of their wind and rain footprints.

  12. The Impact of Dry Saharan Air on Tropical Cyclone Intensification

    NASA Technical Reports Server (NTRS)

    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 two Global Hawk (GH) Unmanned Airborne Systems (UASs) with separate comprehensive environmental and over-storm payloads. The GH flight altitudes (>16.8 km) allow overflights of most convection and sampling of upper-tropospheric winds. Deployments from Goddard s Wallops Flight Facility and 26-hour flight durations will provide coverage of the entire Atlantic Ocean basin, and on-station times up to 5-22 h depending on storm location. Deployments will be in September of 2012 and from late-August to late- September 2013-2014, with up to eleven 26-h flights per deployment.

  13. TROPICAL CYCLONE TORNADOES A RESEARCH AND FORECASTING OVERVIEW. PART 1: CLIMATOLOGIES, DISTRIBUTION AND FORECAST CONCEPTS

    E-print Network

    7.A.1 TROPICAL CYCLONE TORNADOES ­ A RESEARCH AND FORECASTING OVERVIEW. PART 1: CLIMATOLOGIES cyclone (TC) tornadoes represent a relatively small subset of total tornado reports, but garner processes ­ including those involving baroclinicity at various scales ­ appear to contribute to tornado

  14. Extreme rainfall intensities and long-term rainfall risk from tropical cyclones

    E-print Network

    Langousis, Andreas, 1981-

    2009-01-01

    We develop a methodology for the frequency of extreme rainfall intensities caused by tropical cyclones (TCs) in coastal areas. The mean rainfall field associated with a TC with maximum tangential wind speed Vmax, radius ...

  15. Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century

    E-print Network

    Emanuel, Kerry Andrew

    A recently developed technique for simulating large [O(10[superscript 4])] numbers of tropical cyclones in climate states described by global gridded data is applied to simulations of historical and future climate states ...

  16. Does It Make Sense To Modify Tropical Cyclones? A Decision-Analytic Assessment

    E-print Network

    Klima, Kelly

    Recent dramatic increases in damages caused by tropical cyclones (TCs) and improved understanding of TC physics have led DHS to fund research on intentional hurricane modification. We present a decision analytic assessment ...

  17. Tropical cyclones within the sedimentary record : analyzing overwash deposition from event to millennial timescales

    E-print Network

    Woodruff, Jonathan Dalrymple

    2009-01-01

    Tropical cyclone activity over the last 5000 years is investigated using overwash sediments from coastal lagoons on the islands of Vieques, Puerto Rico and Koshikijima, Japan. A simple sediment transport model can reproduce ...

  18. The poleward migration of the location of tropical cyclone maximum intensity

    E-print Network

    Kossin, James P.

    Temporally inconsistent and potentially unreliable global historical data hinder the detection of trends in tropical cyclone activity. This limits our confidence in evaluating proposed linkages between observed trends in ...

  19. Relative impact of climate indicators and aerosols on tropical cyclones

    NASA Astrophysics Data System (ADS)

    Chiacchio, Marc; Pausata, Francesco; Messori, Gabriele; Hannachi, Abdel; Chin, Mian; Ekman, Annica; Barrie, Leonard

    2015-04-01

    This study assesses the most important environmental variables modulating tropical cyclone (TC) frequency in six different oceanic basins such as the East Pacific, West Pacific, North Atlantic, North Indian Ocean, South Indian Ocean, and South Pacific. To determine their influence, we used multiple linear regression between TC frequency and variations in meteorological variables and circulation indices as well as aerosol optical depth (AOD) anomalies over the tropical cyclone development areas for the period 1980-2009 (where the AOD was separated into the compounds black and organic carbon, sulfate dust and sea salt). Overall the low-level relative humidity in the North Atlantic, stratospheric aerosol burden in the East Pacific, and the black carbon burden in the North Indian basin showed the greatest relation with TC activity and were all with statistically significant and explained variances of 28%. Amongst the circulation modes of variability, the Atlantic Multidecadal Oscillation (AMO) and the El Nino Southern Oscillation (ENSO) appeared to be most important to TC activity with significant variances of 29% in the South Indian Ocean and 25% in the East Pacific basins, respectively. We also examined the inter-basin relationship between the different environmental variables in one basin and the cyclone frequency in another basin. Overall the strongest connections were found between North Atlantic basin variables and North Indian TCs while the weakest links were found between West Pacific basin variables and South Pacific TCs. Lastly, because the strongest cooling of the lower stratospheric temperature was found over the North Atlantic since the last few decades and because the cooling could explain a variance of 15% of TC frequency in that same basin, we investigated five global climate models from the historical runs of the CMIP5 archive to determine whether they were able to capture this cooling in the lower stratosphere. Although the models were able to properly simulate the timing of the warming and cooling of the lower stratosphere that follows a volcanic eruption, they showed, for example, about a factor of two stronger cooling compared to the reanalysis. If the TC activity over the North Atlantic is indeed influenced by lower stratospheric cooling following a volcanic eruption, this result warrants the need for a better representation of such physical processes in models so that more accurate projections of TC activity can be made.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Tropical Cyclone rainfall changes in a warmer climate

    NASA Astrophysics Data System (ADS)

    Scoccimarro, Enrico; Villarini, Gabriele; Gualdi, Silvio; Navarra, Antonio; Vecchi, Gabriel; Walsh, Kevin; Zhao, Ming

    2015-04-01

    Possible changes in the intensity of rainfall events associated with tropical cyclones (TCs) are investigated under idealized forcing scenarios, with a special focus on landfalling storms. A new set of experiments designed within the U.S. CLIVAR Hurricane Working Group allows disentangling the relative role of changes in atmospheric carbon dioxide from that played by sea surface temperature (SST) in changing the amount of rainfall associated with TCs in a warmer world. Compared to the present day simulation, we found an increase in TC rainfall under the scenarios involving SST increases. On the other hand, in a CO2 doubling-only scenario, the changes in TC rainfall are small and we found that, on average, TC rainfall tends to decrease compared to the present day climate. The results of this study highlight the contribution of landfalling TCs to the projected increase in the rainfall changes affecting the tropical coastal regions. Scenarios involving SST increases, project a TC rainfall strengthening more evident over land than over ocean. This is linked to the increased lifting effect on the landfalling TCs, induced by an increased instability of the atmospheric column along the coastal regions in a warmer climate.

  2. Classification of rice crops based on submergence due to tropical cyclone using remotely sensed data: an Indian case study

    NASA Astrophysics Data System (ADS)

    Abhyankar, Abhijat A.; Patwardhan, Anand; Inamdar, Arun

    2006-12-01

    Tropical cyclones are one of the most destructive natural disasters occurring frequently in coastal India. The socio economic impacts of these tropical cyclones are high as they result in enormous loss of life and property every year. In the present study, pre event visible-near IR images and post event Radarsat images were procured and used to identify completely submerged landcovers temporally. The methodology is developed considering a case study on the Kendrapara district of Orissa state, which was hit by a cyclone on 29-30 th October 1999. The pre event IRS 1D LISS III (resolution = 22m) image of Kendrapara district was procured geometrically corrected and classified into several landuse and landcover classes. For landuse/landcover classification, supervised classification technique was used. This georeferenced landuse/landcover map provided the baseline information for the district. Next step involved procurement of immediate temporal post-event SAR images of the cyclone-affected district. These images were geometrically corrected and cleaned for speckle noise. Deterministic approach was used to set up threshold for classifying pixel as completely submerged under water or non submerged for Radarsat SAR images i.e. Radarsat SAR images exactly delineated areas completely submerged under water due to cyclonic floods. This type of analysis will help policy makers in determining the extent of submergence and damage. This methodology would be used as a rapid tool to assess damage. Further, this will help in expediting the release of relief funds as well as aid proper allocation of funds to the affected areas/people.

  3. Masking of interannual climate proxy signals by residual tropical cyclone rainwater: Evidence and challenges for low-latitude speleothem paleoclimatology

    NASA Astrophysics Data System (ADS)

    Frappier, Amy Benoit

    2013-09-01

    The anomalously low oxygen isotope ratio (?18O values) of tropical cyclone rainfall can transfer proxy information about past tropical cyclone activity to stalagmite oxygen isotope records. Isotopically distinct stormwater reaches the growing crystal surface as a coherent slug, or after attenuation by mixing with isotopically normal vadose groundwaters. A high-resolution micromilled stalagmite stable isotope record from Belize shows that residual tropical cyclone water from Hurricane Mitch masked the oxygen isotope record of a major El Niño event. On decadal time scales, measured ?18O values are affected by changes in local tropical cyclone frequency. Despite the tropical cyclone masking effect, the structure of the "missing" El Niño event is preserved in the ATM-7 carbon isotope ratios (?13C values). In tropical cyclone-prone regions, the fidelity of stalagmite oxygen isotope proxy data to recording background climate signals is modulated by temporal variations in local tropical cyclone rainfall, and the sensitivity of individual stalagmites to tropical cyclone masking varies with hydrology. Speleothem ?13C values, unaffected by tropical cyclones, can preserve the underlying structure of climatic variability. For low-latitude speleothems with C-O isotope covariance, intervals in which the ?18O values are significantly lower than ?13C values predict may indicate periods when local tropical cyclone masking of isotope-derived precipitation records is enhanced by greater infiltration of tropical cyclone rain. The temporal structure in stalagmite C-O isotope covariance has paleoenvironmental meaning that may be revealed by exploring factors associated with independent behavior in each isotope ratio, respectively. Tropical cyclone masking presents new challenges to paleoclimatology and a source of hypotheses for paleotempestology.

  4. Reconciling droughts and landfalling tropical cyclones in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Misra, Vasubandhu; Bastola, Satish

    2015-05-01

    A popular perception is that landfalling tropical cyclones help to mitigate droughts in the Southeastern United States (SeUS). However intriguing paradigms on the role of large scale SST variations on continental US including SeUS droughts and seasonal Atlantic tropical cyclone activity confronts us. These paradigms suggest that in the presence of warm (cold) eastern tropical Pacific and cold (warm) Atlantic Ocean sea surface temperature anomaly (SSTA) lead to the increased likelihood of wetter (drier) conditions over the continental US including the SeUS. Juxtaposing this understanding with the fact that landfalling tropical cyclones contribute significantly to the annual mean total rainfall in the SeUS and in El Niño (La Niña) years with cold (warm) tropical Atlantic SSTA lead to reduced (increased) Atlantic tropical cyclone activity raises a conflict on the role of the large-scale SST variations in SeUS hydroclimate. This study attempts to investigate the apparent dichotomous role of the large scale SST variations on the SeUS hydrology by examining the role of rainfall from landfalling tropical cyclones in the SeUS to local seasonal droughts. Our study finds that the contribution of the rainfall from landfalling tropical cyclone on the mitigation of monthly drought in the 28 SeUS watersheds is relatively insignificant. So much so that the hydrological model uncertainty in estimating the drought index over the 28 SeUS watersheds is larger than the sensitivity exhibited by the drought index to the inclusion of rain from landfalling tropical cyclone. The conclusions of this study are justified by the fact that the timing of the landfalling tropical cyclone in relation to overall soil moisture conditions of the watershed does not coincide with a drought like situation in the 1948-2006 time period analyzed in this study. This largely stems from the fact that the large-scale flow pattern resulting in abundant (lack of) advection of moisture for anomalously wet (dry) summer and fall seasons in the SeUS emanating from the source region of the Caribbean Sea and the northwestern tropical Atlantic Ocean coincides with the steering flow of the Atlantic tropical cyclones bound to make landfall in the SeUS (recurving away from the SeUS).

  5. Effects of tropical North Atlantic SST on tropical cyclone genesis in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Yu, Jinhua; Li, Tim; Tan, Zhemin; Zhu, Zhiwei

    2015-04-01

    The tropical cyclone genesis number (TCGN) in July-October (JASO) over the western North Pacific (WNP) exhibits a robust interannual variation. It shows a longitudinally tri-pole pattern with a high in the eastern WNP and South China Sea (SCS) and a low in the western WNP, which explain 42.2 and 23.4 % of total TCGN variance in the eastern WNP and SCS, respectively. The high-low-high pattern is similar to that derived from a TC genesis potential index (GPI). To understand the cause of the longitudinal distribution of the dominant interannual mode, we examine the contributions of environmental parameters associated with GPI. It is found that relative humidity and relative vorticity are important factors responsible for TC variability in the SCS, while vertical shear and relative vorticity are crucial in determining TC activity in eastern WNP. A simultaneous correlation analysis shows that the WNP TCGN in JASO is significantly negatively correlated (with a correlation coefficient of -0.5) with sea surface temperature anomalies (SSTA) in the tropical North Atlantic (TNA). The longitudinal distribution of TC genesis frequency regressed onto TNA SSTA resembles that regressed upon the WNP TCGN series. The spatial patterns of regressed environmental variables onto the SSTA over the TNA also resemble those onto TCGN in the WNP, that is, an increase of relative humidity in the SCS and a weakening of vertical shear in the eastern WNP are all associated with cold SSTA in the TNA. Further analyses show that the cold SSTA in the TNA induce a negative heating in situ. In response to this negative heating, a low (upper)-level anomalous aniti-cyclonic (cyclonic) flows appear over the subtropical North Atlantic and eastern North Pacific, and to east of the cold SSTA, anomalous low-level westerlies appear in the tropical Indian Ocean. Given pronounced mean westerlies in northern Indian Ocean in boreal summer, the anomalous westerly flows increase local surface wind speed and surface evaporation and cool the SST in situ. Cold SSTA in northern Indian Ocean further suppress local convection, inducing anomalous westerlies to its east, leading to enhanced cyclonic vorticity and low surface pressure over the WNP monsoon trough region. Idealized numerical experiments further confirm this Indian Ocean relaying effect, through which cold SSTA in the tropical Atlantic exert a remote impact to circulation in the WNP.

  6. Putting to rest WISHE-ful misconceptions for tropical cyclone intensification

    NASA Astrophysics Data System (ADS)

    Montomery, Michael T.; Persing, John; Smith, Roger K.

    2015-03-01

    The purpose of this article is twofold. The first is to point out and correct several misconceptions about the putative WISHE mechanism of tropical cyclone intensification that currently are being taught to atmospheric science students, to tropical weather forecasters, and to laypeople who seek to understand how tropical cyclones intensify. The mechanism relates to the simplest problem of an initial cyclonic vortex in a quiescent environment. This first part is important because the credibility of tropical cyclone science depends inter alia on being able to articulate a clear and consistent picture of the hypothesized intensification process and its dependencies on key flow parameters. The credibility depends also on being able to test the hypothesized mechanisms using observations, numerical models, or theoretical analyses. The second purpose of the paper is to carry out new numerical experiments using a state-of-the-art numerical model to test a recent hypothesis invoking the WISHE feedback mechanism during the rapid intensification phase of a tropical cyclone. The results obtained herein, in conjunction with prior work, do not support this recent hypothesis and refute the view that the WISHE intensification mechanism is the essential mechanism of tropical cyclone intensification in the idealized problem that historically has been used to underpin the paradigm. This second objective is important because it presents a simple way of testing the hypothesized intensification mechanism and shows that the mechanism is neither essential nor the dominant mode of intensification for the prototype intensification problem. In view of the operational, societal, and scientific interest in the physics of tropical cyclone intensification, we believe this paper will be of broad interest to the atmospheric science community and the findings should be useful in both the classroom setting and frontier research.

  7. Perspective: coordinating paleoclimate research on tropical cyclones with hurricane-climate theory and modelling

    Microsoft Academic Search

    AMY F RAPPIER; T HOMAS K NUTSON; K AM-BIU L IU; K ERRY E MANUEL

    2007-01-01

    Extending the meteorological record back in time can offer critical data for assessing tropical cyclone-climate links. While paleotempestology, the study of ancient storms, can provide a more realistic view of past 'worst case scenarios', future environmental conditions may have no analogues in the paleoclimate record. The primary value in paleotem- pestology proxy records arises from their ability to quantify climate-tropical

  8. Isotopic spikes from tropical cyclones in surface waters: Opportunities in hydrology and paleoclimatology

    Microsoft Academic Search

    James R Lawrence

    1998-01-01

    The stable isotopic ratio of precipitation from tropical cyclones is very low compared to that of normal summer precipitation (Lawrence and Gedzelman, 1996). Tropical Storms Allison and Chantal made landfall in southeast Texas in the summer of 1989 and dumped large amounts of rain. Isotope ratios of surface waters measured at five different sites decreased markedly after the passage and

  9. On the Wavelength of the Rossby Waves Radiated by Tropical Cyclones KYLE D. KROUSE

    E-print Network

    Sobel, Adam

    On the Wavelength of the Rossby Waves Radiated by Tropical Cyclones KYLE D. KROUSE Department depression­type disturbances, which occur as a result of Rossby wave radiation from a preexisting tropical flow of the radiated Rossby waves and that of the TC. The authors argue that either horizontal

  10. Tropical Cyclone Paka's Initial Explosive Development (10-12 December, 1997)

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Halverson, Jeff; Simpson, Joanne; Olson, William; Pierce, Harold

    1999-01-01

    Convection associated with an equatorial westerly wind burst was first observed late November during the strong El Nino of 1997 at approximately 2000 km southwest of the Hawaiian Islands. This region of convection lead to the formation of twin tropical cyclones, one in the southern hemisphere named Pam and the other in the northern hemisphere named Paka. During the first week in December, tropical cyclone Paka, the system of concern, reached tropical storm stage as it moved rapidly westward at relatively low latitudes. During the 10-12 of December, Paka rapidly developed into a typhoon.

  11. Pollution and dust aerosols modulating tropical cyclones intensities

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Clavner, Michal; Nirel, Ronit

    2011-10-01

    Tropical cyclones (TC) are propelled mostly by realization of latent heat that is stored in vapor coming off warm sea surfaces. The heating occurs when the vapor condenses into cloud drops. Re-evaporation of the cloud water takes back the released heat, whereas precipitation of the water as rain fixates the heat in the air. Therefore, it is expected that TC intensities would be sensitive to precipitation forming processes that affect the amount and distribution of latent heat release. This has been simulated by numerical models, which showed that cloud condensation nuclei (CCN) aerosols weaken the storms apparently by slowing the conversion of cloud drops into precipitation. If so, we should expect that storm predictions that do not take this aerosol effect into account would over-predict TC intensities. Here we show that increased aerosols quantities in a TC periphery can explain about 8% of the forecast errors of the TC. Indeed, actual intensities of polluted TCs were found to be on average lower than their predicted values, providing supporting observational evidence to the hypothesis. It was also found that TC intensity might be more susceptible to the impacts of aerosols during their developing stages and less in the TC mature and dissipating stages.

  12. The dry intrusion perspective of extra-tropical cyclone development

    NASA Astrophysics Data System (ADS)

    Browning, K. A.

    1997-12-01

    The dry intrusion is a coherent region of air descending from near tropopause-level. It often has a clear signature in satellite imagery, especially in the water vapour channel, where it is seen as a ‘dark zone’. Parts of dry intrusions are characterised by high potential vorticity and, upon approaching a low-level baroclinic zone, rapid cyclogenesis may be expected to ensue. The leading edges of dry intrusions are defined by cold [theta]w-fronts (moisture fronts). In some places the dry intrusion undercuts rearward-ascending warm air to give an ana-cold front. In other places it overruns the warm air to produce an upper cold [theta]w-front in advance of the surface cold front. Here the dry intrusion is associated with the generation of potential instability and its eventual release as showers or thunderstorms. Identification of dry intrusions provides the forecaster with additional nowcasting evidence that is especially helpful when issuing severe weather warnings. The identification of water vapour dark zones associated with dry intrusions can also form the basis of methods for validating NWP models. Through their relationship to high potential vorticity, they can provide guidance for bogussing NWP models in situations of potentially severe weather. This article provides an introduction to the structure and behaviour of dry intrusions and their relationship to other aspects of extra-tropical cyclones.

  13. Impact of environmental moisture on tropical cyclone intensification

    NASA Astrophysics Data System (ADS)

    Wu, L.; Su, H.; Fovell, R. G.; Dunkerton, T. J.; Wang, Z.; Kahn, B. H.

    2015-06-01

    The impacts of environmental moisture on the intensification of a tropical cyclone (TC) are investigated in the Weather Research and Forecasting (WRF) model, with a focus on the azimuthal asymmetry of the moisture impacts. A series of sensitivity experiments with varying moisture perturbations in the environment are conducted and the Marsupial Paradigm framework is employed to understand the different moisture impacts. We find that modification of environmental moisture has insignificant impacts on the storm in this case unless it leads to convective activity in the environment, which deforms the quasi-Lagrangian boundary of the storm. By facilitating convection and precipitation outside the storm, enhanced environmental moisture ahead of the northwestward-moving storm induces a dry air intrusion to the inner core and limits TC intensification. However, increased moisture in the rear quadrants favors intensification by providing more moisture to the inner core and promoting storm symmetry, with primary contributions coming from moisture increase in the boundary layer. The different impacts of environmental moisture on TC intensification are governed by the relative locations of moisture perturbations and their interactions with the storm Lagrangian structure.

  14. An ocean coupling potential intensity index for tropical cyclones

    NASA Astrophysics Data System (ADS)

    Lin, I.-I.; Black, P.; Price, J. F.; Yang, C.-Y.; Chen, S. S.; Lien, C.-C.; Harr, P.; Chi, N.-H.; Wu, C.-C.; D'Asaro, E. A.

    2013-05-01

    Timely and accurate forecasts of tropical cyclones (TCs, i.e., hurricanes and typhoons) are of great importance for risk mitigation. Although in the past two decades there has been steady improvement in track prediction, improvement on intensity prediction is still highly challenging. Cooling of the upper ocean by TC-induced mixing is an important process that impacts TC intensity. Based on detail in situ air-deployed ocean and atmospheric measurement pairs collected during the Impact of Typhoons on the Ocean in the Pacific (ITOP) field campaign, we modify the widely used Sea Surface Temperature Potential Intensity (SST_PI) index by including information from the subsurface ocean temperature profile to form a new Ocean coupling Potential Intensity (OC_PI) index. Using OC_PI as a TC maximum intensity predictor and applied to a 14 year (1998-2011) western North Pacific TC archive, OC_PI reduces SST_PI-based overestimation of archived maximum intensity by more than 50% and increases the correlation of maximum intensity estimation from r2 = 0.08 to 0.31. For slow-moving TCs that cause the greatest cooling, r2 increases to 0.56 and the root-mean square error in maximum intensity is 11 m s-1. As OC_PI can more realistically characterize the ocean contribution to TC intensity, it thus serves as an effective new index to improve estimation and prediction of TC maximum intensity.

  15. Measuring NWP Skill of Tropical Cyclones in Shanghai Meteorological Service

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Xu, Xiaolin; Chen, Baode

    2014-05-01

    A WRF based typhoon NWP system for operations, namely, the SMS-THRAPS (Shanghai Meteorological Service-Tropical cyclone High Resolution Analysis and Prediction System), has been developed in Shanghai Typhoon Institute (STI). It mainly consists of the Gridpoint Statistical Interpolation (GSI) data assimilation, a complex cloud analysis (CCS) package and the WRF3.5. A significant number of local observations such as SYNOP, SHIP, BUOY, METAR, AMDAR, CINRAD and AWS can be assimilated into the system. The model is configured with a mesh of 9 km horizontal resolution covering an area about 6000km×5000km and a moving nest of 7°×7° at 3 km grid distance. Numerical experiments for Super typhoon "MEGI" (2012) during landfall stage indicated that assimilation of local observations is very important for improving the accuracy of typhoon track, intensity forecasts, particularly, local rainfall distribution. The SMS-THRAPS performance in 2013 was evaluated and compared with ECWMF and JAPAN global numerical forecasts. The results show that SMS-THRAPS's track forecast is similar to ECWMF and better than JAPAN. SMS-THRAPS is the best in sea level pressure forecast at leading time < 42 hours, and worse than ECWMF, better than JAPAN at leading time > 42 hours. Key words: High resolution, Typhoon, Assimilation

  16. Tropical Indian Ocean Influence on Northwest Pacific Tropical Cyclones Following Strong El Nino

    NASA Astrophysics Data System (ADS)

    Du, Y.; Yang, L.; Xie, S.

    2010-12-01

    Following a strong El Nino, tropical cyclone (TC) number decreases over the Northwest (NW) Pacific despite little change in local sea surface temperature. Our analysis suggests El Nino-induced tropical Indian Ocean (TIO) warming play an important role. The TIO warming forces a warm tropospheric Kelvin wave that propagates into the western Pacific. Inducing surface divergence off the equator, the tropospheric Kelvin wave suppresses convection and induces an anomalous anticyclone over the NW Pacific, both anomalies unfavorable for TCs. The westerly vertical shear associated with the warm Kelvin wave reduces the magnitude of vertical shear in the South China Sea and strengthens it in the NW Pacific, an east-west variation that causes TC activity to increase and decrease in respective regions. These results help improve seasonal TC prediction.

  17. The role of tropical Atlantic SST anomalies in modulating western North Pacific tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Huo, Liwei; Guo, Pinwen; Hameed, Saji N.; Jin, Dachao

    2015-04-01

    The connection between north tropical Atlantic (NTA) sea surface temperature (SST) anomalies and tropical cyclone (TC) genesis over the western North Pacific (WNP) and associated physical mechanisms are investigated in this study. We demonstrate a remarkable negative correlation of WNP TC genesis frequency with the (preceding) boreal spring NTA SST anomalies. Our analysis suggests that major factors for TC genesis including distributions of large-scale vorticity and midtropospheric humidity are rendered unfavorable by remote teleconnections while barotropic energy conversion from the large-scale flow is suppressed. As shown in recent studies, the remote teleconnection from the Atlantic is sustained and enhanced throughout the typhoon season through local air-sea interactions. These results suggest that boreal spring NTA SST anomaly could be a new predictor for the seasonal WNP TC activity.

  18. Response of Seasonal Atlantic Tropical Cyclone Activity to Suppression of African Easterly Waves in a Regional Climate Model

    NASA Astrophysics Data System (ADS)

    Patricola, C. M.; Saravanan, R.; Chang, P.

    2014-12-01

    Atlantic tropical cyclones and African easterly waves (AEWs) are strongly linked on the synoptic timescale, with about 85% of observed major Atlantic hurricanes originating from AEWs (e.g., Landsea et al. 1993). However, the influence of variability in AEWs on seasonal Atlantic tropical cyclone activity is not fully understood; a positive correlation between AEW activity and Atlantic tropical cyclone activity exists on the interannual timescale during just some periods of the observational record (e.g., Thorncroft and Hodges, 2001; Hopsch et al. 2007). This study investigates the impact of AEWs on seasonal Atlantic tropical cyclone activity using regional climate model simulations in which AEWs were either prescribed or removed through the lateral boundary condition (LBC). The control simulation (10-member ensemble) was run at 27 km resolution and used 6-hourly LBCs from the NCEP CFS Reanalysis and daily NOAA Optimum Interpolation (OI) V2 sea surface temperature (SST) from the year 2005. In the experiment AEWs were suppressed by filtering 2-10 day variability over tropical latitudes from the eastern LBC, located along the west coast of the Sahel. The difference in Atlantic tropical cyclone frequency was insignificant between the simulations in which AEWs were prescribed versus suppressed, indicating that AEWs are not necessary to maintain climatological tropical cyclone frequency even though tropical cyclones readily originate from these features. This further implies that seasonal Atlantic tropical cyclone frequency is uninfluenced by variability in AEWs, and that the value of AEW variability as a predictor of Atlantic tropical cyclones is limited to the weekly timescale. However in response to filtering AEWs, accumulated cyclone energy significantly increased by about 15% of the control simulation mean and the spatial pattern of track density shifted in association with changes in steering winds. This suggests the importance of AEWs in impacting tropical cyclone tracks through their influence on the large-scale circulation via wave-mean flow interaction.

  19. Regional climate model projections of rainfall from U.S. landfalling tropical cyclones

    NASA Astrophysics Data System (ADS)

    Wright, Daniel B.; Knutson, Thomas R.; Smith, James A.

    2015-03-01

    The eastern United States is vulnerable to flooding from tropical cyclone rainfall. Understanding how both the frequency and intensity of this rainfall will change in the future climate is a major challenge. One promising approach is the dynamical downscaling of relatively coarse general circulation model results using higher-resolution regional climate models (RCMs). In this paper, we examine the frequency of landfalling tropical cyclones and associated rainfall properties over the eastern United States using Zetac, an 18-km resolution RCM designed for modeling Atlantic tropical cyclone activity. Simulations of 1980-2006 tropical cyclone frequency and rainfall intensity for the months of August-October are compared against results from previous studies and observation-based datasets. The 1980-2006 control simulations are then compared against results from three future climate scenarios: CMIP3/A1B (late twenty-first century) and CMIP5/RCP4.5 (early and late twenty-first century). In CMIP5 early and late twenty-first century projections, the frequency of occurrence of post-landfall tropical cyclones shows little net change over much of the eastern U.S. despite a decrease in frequency over the ocean. This reflects a greater landfalling fraction in CMIP5 projections, which is not seen in CMIP3-based projections. Average tropical cyclone rain rates over land within 500 km of the storm center increase by 8-17 % in the future climate projections relative to control. This is at least as much as expected from the Clausius-Clapeyron relation, which links a warmer atmosphere to greater atmospheric water vapor content. Over land, the percent enhancement of area-averaged rain rates from a given tropical cyclone in the warmer climate is greater for larger averaging radius (300-500 km) than near the storm, particularly for the CMIP3 projections. Although this study does not focus on attribution, the findings are broadly consistent with historical tropical cyclone rainfall changes documented in a recent observational study. The results may have important implications for future flood risks from tropical cyclones.

  20. Assessing Impacts of Global Warming on Tropical Cyclone Tracks

    NASA Technical Reports Server (NTRS)

    Wu, Li-Guang; Wang, Bin

    2003-01-01

    A new approach is proposed to assess the possible impacts of the global climate change on tropical cyclone (TC) tracks in the western North Pacific (WNP) basin. The idea is based on the premise that the future change of TC track characteristics is primarily determined by changes in large-scale environmental steering flows. It is demonstrated that the main characteristics of the current climatology of TC tracks can be derived from the climatological mean velocity field of TC motion by using a trajectory model. The climatological mean velocity of TC motion, which is composed of the large-scale steering and beta drift, is determined on each grid of the basin. The mean beta drift is estimated from the best track data, and the mean large-scale steering flow is computed from the NCEP/NCAR reanalysis for the current climate state. The derived mean beta drift agrees well with the results of previous observational and numerical studies in terms of its direction and magnitude. The outputs of experiments A2 and B2 of the Geophysical Fluid Dynamics Laboratory (GFDL) R30 climate model suggest that the subtropical high will be persistently weak over the western part of the WNP or shift eastward during July-September in response to the future climate change. By assuming that the mean beta drift in the future climate state is unchanged, the change in the general circulation by 2059 will decrease the TC activities in the WNP, but favor a northward shift of typical TC tracks. As a result, the storm activities in the South China Sea will decrease by about 12%, while the Japan region will experience an increase of TCs by 12-15%. During the period of 2000-2029, the tropical storms that affect the China region will increase by 5-6%, but return to the current level during 2030-2059. It is also suggested that, during the period of 2030-2059 tropical storms will more frequently affect Japan and the middle latitude region of China given that the formation locations remain the same as in the current climate state.

  1. An Extended Forecast of the Frequencies of North Atlantic Basin Tropical Cyclone Activity for 2009

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2009-01-01

    An extended forecast of the frequencies for the 2009 North Atlantic basin hurricane season is presented. Continued increased activity during the 2009 season with numbers of tropical cyclones, hurricanes, and major hurricanes exceeding long-term averages are indicated. Poisson statistics for the combined high-activity intervals (1950-1965 and 1995-2008) give the central 50% intervals to be 9-14, 5-8, and 2-4, respectively, for the number of tropical cyclones, hurricanes, and major hurricanes, with a 23.4% chance of exceeding 14 tropical cyclones, a 28% chance of exceeding 8 hurricanes, and a 31.9% chance of exceeding 4 major hurricanes. Based strictly on the statistics of the current high-activity interval (1995-2008), the central 50% intervals for the numbers of tropical cyclones, hurricanes, and major hurricanes are 12-18, 6-10, and 3-5, respectively, with only a 5% chance of exceeding 23, 13, or 7 storms, respectively. Also examined are the first differences in 10-yr moving averages and the effects of global warming and decadal-length oscillations on the frequencies of occurrence for North Atlantic basin tropical cyclones. In particular, temperature now appears to be the principal driver of increased activity and storm strength during the current high-activity interval, with near-record values possible during the 2009 season.

  2. Assessing the importance of tropical cyclones on continental margin sedimentation in the Mississippi delta region

    Microsoft Academic Search

    Michael. B. Dail; D. Reide Corbett; J. P. Walsh

    2007-01-01

    Recent research on the Mississippi margin indicates notable seasonal variation in seabed dynamics. During years with minimal tropical-system activity, sediments initially deposited from late spring to early fall are remobilized by wind-driven currents and wave energy during extra-tropical weather systems in the winter. This research reveals the profound significance of tropical cyclones on Louisiana Shelf sedimentation. The amount of material

  3. Factors That Influence the Size of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Toumi, Ralf; Czaja, Arnaud; Van Kan, Adrian

    2015-04-01

    Tropical cyclone (TC) size is an important feature setting the extent of coastal flooding, the size of storm surge and area threatened by landfall. The importance of TC size is demonstrated comparing Hurricanes Sandy in 2012 and Bret in 1999. As a Saffir-Simpson Hurricane Scale category-3 hurricane, the radius of gale-force wind of Hurricane Sandy exceeded 800 km prior to landfall, and the storm caused catastrophic storm surge into the New Jersey and New York coastlines, and damage up to an estimated total of 50 billion. Hurricane Bret, on the other hand, was a more intense category-4 hurricane with a radius of gale-force wind of only 140 km. Although Bret's intensity is considerable, damage was reported to be relatively light, totalling an estimated 60 million. The difference impacts are mainly caused by the difference in size. Despite the fact that a wide range of observed TC sizes has been recognised, the underlying factors that control both individual storm size and the climatological size variation remain mysterious. Here an idealized full-physics numerical cyclone model and a modified hurricane steady-state model (? model) for TC wind profile are used to investigate the influence of environmental temperature and initial vortex properties on TC size. In the simulation we find that a sea surface temperature increase, a temperature decrease in the upper troposphere, a large or strong initial vortex can lead to the extension of TC size. The numerical model simulations show a Gaussian distribution with width, ?, of the moist entropy in the boundary layer. The width, ?, has good linear relationship with the size changes caused by different factors. With regards to TC size and intensity, we find that, unlike the intensity prediction based on the maximum potential intensity theory, it seems that there is no upper limit for TC size providing there is sufficient latent heat flux. The increase of TC size at the steady stage also causes a slight drop in intensity. In addition, a weak relationship between TC size and intensity is confirmed in the simulations, and this relationship can be understood with the ? model. The ? model correctly depicts the tangential velocity profile at the top of boundary layer (TBL). Based on the ? model, the TC size is a function of the distribution of moist entropy at the TBL given by ?, the pressure drop from the ambient environment to the eye, and the Coriolis parameter. We establish that for the size the width of the entropy distribution close to the core is more important than the environmental entropy or the difference between the environment and the core entropy. One can predict TC size by understanding what sets the width, ?.

  4. Tropical cyclone track Analysis over Indian Coast Using Spatio-Temporal data-mining

    NASA Astrophysics Data System (ADS)

    Mohapatra, Gyanendranath; Manjunath, Swetha; Behera, Sasmita; Mohanty, Pratap Kumar

    2015-04-01

    Tropical cyclones are a natural hazard which largely affects the lives and property with its destructive wind and heavy rainfall. Fluctuations in the frequency and intensity complicate the detection of long-term trends and play an important role in the global climate system; therefore understanding and predicting tropical cyclones track, intensity, and landfall location is of both societal and scientific significance. In this study a data-mining approach is being used to analyze the tropical cyclone track both in the temporal and spatial scale. Basically, the Indian coast line is divided into four zones viz. north east, south east in the eastern side adjoining Bay of Bengal and North west and south west in the western side adjoining Arabian sea as these coastal areas are very much vulnerable for disaster due to maximum number of landfall of Tropical Cyclones. The track and landfall associated with all the cyclones are clustered based on their intensity (Severe, moderate and low) and landfall location. The analyses are carried out for landfall location and the extent of track separately for the events happening in two seasons i.e. pre-monsoon and post-monsoon period. Along with categorization of intensity, trend analysis of track and the targeted zone of maximum damage also been studied. Algorithms are being developed for potential resilient and impact assessment of the parameters associated with cyclone disaster in the coastal region of India. One of the important objectives of this present work is also the identification of most disaster prone coastal area and becoming a part of the information support system during the cyclone period. Based on the statistics like mean, Standard Deviation, regression and correlation analysis, an index is developed which determines the level of damage and vulnerability along the coastal region. This index can be used for the early warning system of particular coastal areas for the preparedness and mitigation of future cyclone events.

  5. Cost-benefit analysis of a green electricity system in Japan considering the indirect economic impacts of tropical cyclones

    Microsoft Academic Search

    Miguel Esteban; Qi Zhang; Gorka Longarte-Galnares

    2012-01-01

    Global warming is likely to profoundly influence future weather patterns, and one consequence of this is the likelihood of an increase in tropical cyclone intensity. The present paper presents a cost-benefit analysis of introducing significant amounts of green energy in the electricity system in Japan in the light of the economic damage that an increase in tropical cyclone intensity could

  6. Climate response to tropical cyclone-induced ocean mixing in an1 Earth system model of intermediate complexity2

    E-print Network

    Climate response to tropical cyclone-induced ocean mixing in an1 Earth system model of intermediate system model of intermediate complexity. The parameterization is based on21 previously published global. Abstract19 We introduce a parameterization of ocean mixing by tropical cyclones (TCs) into20 an Earth

  7. THE DEADLIEST, COSTLIEST, AND MOST INTENSE UNITED STATES TROPICAL CYCLONES FROM 1851 TO 2006 (AND OTHER FREQUENTLY REQUESTED HURRICANE FACTS)

    Microsoft Academic Search

    Eric S. Blake; Edward N. Rappaport; Christopher W. Landsea; NHC Miami

    This technical memorandum lists the deadliest tropical cyclones in the United States during 1851- 2006 and the costliest tropical cyclones in the United States during 1900-2006. The compilation ranks damage, as expressed by monetary losses, in three ways: 1) contemporary estimates; 2) contemporary estimates adjusted by inflation to 2006 dollars; and 3) contemporary estimates adjusted for inflation and the growth

  8. Impact of Tropical Cyclones on the Heat Budget of the South Pacific Ocean S. JULLIEN,* C. E. MENKES,1

    E-print Network

    Impact of Tropical Cyclones on the Heat Budget of the South Pacific Ocean S. JULLIEN,* C. E. MENKES cyclones (TCs) in the South Pacific convergence zone through a complete ocean heat budget. The TC impact, in final form 4 May 2012) ABSTRACT The present study investigates the integrated ocean response to tropical

  9. Tropical Cyclone Changes in the Western North Pacific in a Global Warming Scenario MARKUS STOWASSER, YUQING WANG, AND KEVIN HAMILTON

    E-print Network

    Wang, Yuqing

    Tropical Cyclone Changes in the Western North Pacific in a Global Warming Scenario MARKUS STOWASSER The influence of global warming on the climatology of tropical cyclones in the western North Pacific basin Model version 2 (CCSM2) coupled global climate model. The regional model is first tested in 10 yr

  10. Edwards, R., 2012: Tropical cyclone tornadoes: A review of knowledge in research and prediction. Electronic J. Severe Storms Meteor., 7 (6), 161.

    E-print Network

    Edwards, R., 2012: Tropical cyclone tornadoes: A review of knowledge in research and prediction. Electronic J. Severe Storms Meteor., 7 (6), 1­61. 1 Tropical Cyclone Tornadoes: A Review of Knowledge of tropical cyclone (TC) tornadoes has spanned portions of ten decades, but has been missing a documentary

  11. Characterization of the Tropical-Cyclone-Induced Multi-Hazard Extreme Distribution of Coastal Flooding

    NASA Astrophysics Data System (ADS)

    Diez Sierra, J.; Toimil, A.; del Jesus, M.; Méndez Incera, F. J.; Medina, R.

    2014-12-01

    Coastal areas are among the most populated regions on Earth. They constitute the interface between continental land and the ocean. For this reason they are subject to complex flooding dynamics that arise from the interaction of coastal and continental dynamics. This complexity complicates the analysis of the changes induced by climate change on the distribution of extreme events. In this work, we develop a methodology to characterize the extreme distribution of flooding induced by tropical cyclones in coastal environments under different climates, considering marine dynamics (storm surge and wave run-up) and continental dynamics (precipitation and runoff).The approach followed in this work begins by selecting the tropical cyclones that affected the study area in the past; augmenting it with synthetically-generated cyclones. The maximum dissimilarity algorithm is then used on the dataset to select for dynamical downscaling the K tropical cyclones that best represent the variability on the data. Numerical simulations are carried out for these K tropical cyclones to derive the spatial fields of wind (by means of the Hydromet-Rankine Vortex model) and rainfall (using R-Clipper model) induced by the cyclone. SWAN model is used to derive the wave fields, H2D to derive the storm surge fields and a CUENCAS-like model (IH-Mole) to derive runoff fields. All the flood-inducing dynamics are the input to the RFSM-EDA model that computes flood depths for the study area.Having completed the dynamical downscaling database, a Monte Carlo simulation is used to generate synthetic time series of tropical cyclone occurrence. Tropical cyclone climate is related to the spatial patterns of sea surface temperature (SST) fields, which are used in turn as the main driver of a Monte Carlo simulation. Flood time series are derived from cyclone time series using the dynamical downscaling database and interpolation, for those cyclones that have not been simulated.Our hybrid approach (mixing statistical and dynamical downscaling) allows us to compute any statistic of the complete flooding distribution at every location of the study site. Moreover, making use of SST data from simulations of future climate, obtained from general circulation models, we can study the effects of climate change in these distributions of extremes.

  12. Effects of surface heat flux-induced sea surface temperature changes on tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Shen, Weixing; Ginis, Isaac

    2003-09-01

    It is known that in deep and open oceans, the effect of sea surface sensible and evaporative heat fluxes on the tropical cyclone-induced sea surface cooling is small compared to that caused by turbulent mixing and cold water entrainment into the upper ocean mixed-layer. This study shows that tropical cyclone-induced surface heat fluxes dominate the surface cooling in near-coastal shallow ocean regions with limited or no underlying cold water. The thermal response of the ocean to the surface heat fluxes is nearly one dimensional through very quick vertical mixing in the ocean mixed layer. The flux-induced sea surface cooling may lead to appreciable reduction of storm intensity if the storm moves slowly. It is therefore important to account this negative feedback of ocean coupling in near-coastal regions for more skillful forecasting of landfalling tropical cyclones.

  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

    NASA Technical Reports Server (NTRS)

    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 later and with both being related to global warming. In this study, the relationship between the LOS and tropical cyclone activity and climate is examined for the weather satellite era, 1960-2013. Estimates are also given for the LOS and LSD, as well as for the expected number of tropical cyclones (NTC), the total number of storm days (NSD), the total accumulated cyclone energy (ACE), and the net tropical cyclone activity (NTCA) index for the 2014 hurricane season.

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

    NASA Technical Reports Server (NTRS)

    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 cyclones NOT interacted with thc developing baroclinic disturbance as it penetrated the western MED. To do so, we first remove the moisture and dynamical features of the two vestigial tropical cyclones from the large scale meteorological fields used to initialize the Mediterranean cyclone simulation. This is done through depletion of the moisture front associated with the two tropical cyclones, accomplished by relaxation to the suppressed east Atlantic conditions. The dynamical effects are removed through energetic destruction of the latter stages of the eastward traveling tropical cyclones, accomplished by lowering the underlying sea surface temperatures. A precipitation-distribution impact experiment is then run by initializing with the customized large-scale fields. The final precipitation-impact field is described by differencing the "impact" run from the "control" run -- the latter defined as the original simulation which intrinsically includes the effects of the two vestigial tropical cyclones.

  15. Assessing the Importance of Atlantic Basin Tropical Cyclone Steering Currents in Anticipating Landfall Risk

    NASA Astrophysics Data System (ADS)

    Truchelut, R.; Hart, R. E.

    2013-12-01

    While a number of research groups offer quantitative pre-seasonal assessments of aggregate annual Atlantic Basin tropical cyclone activity, the literature is comparatively thin concerning methods to meaningfully quantify seasonal U.S. landfall risks. As the example of Hurricane Andrew impacting Southeast Florida in the otherwise quiet 1992 season demonstrates, an accurate probabilistic assessment of seasonal tropical cyclone threat levels would be of immense public utility and economic value; however, the methods used to predict annual activity demonstrate little skill for predicting annual count of landfalling systems of any intensity bin. Therefore, while current models are optimized to predict cumulative seasonal tropical cyclone activity, they are not ideal tools for assessing the potential for sensible impacts of storms on populated areas. This research aims to bridge the utility gap in seasonal tropical cyclone forecasting by shifting the focus of seasonal modelling to the parameters that are most closely linked to creating conditions favorable for U.S. landfalls, particularly those of destructive and costly intense hurricanes. As it is clear from the initial findings of this study that overall activity has a limited influence on sensible outcomes, this project concentrates on detecting predictability and trends in cyclogenesis location and upper-level wind steering patterns. These metrics are demonstrated to have a relationship with landfall activity in the Atlantic Basin climatological record. By aggregating historic seasonally-averaged steering patterns using newly-available reanalysis model datasets, some atmospheric and oceanic precursors to an elevated risk of North American tropical cyclone landfall have been identified. Work is ongoing to quantify the variance, persistence, and predictability of such patterns over seasonal timescales, with the aim of yielding tools that could be incorporated into tropical cyclone risk mitigation strategies.

  16. How do beetle assemblages respond to cyclonic disturbance of a fragmented tropical rainforest landscape?

    PubMed

    Grimbacher, Peter S; Stork, Nigel E

    2009-09-01

    There are surprisingly few studies documenting effects of tropical cyclones (including hurricanes and typhoons) on rainforest animals, and especially insects, considering that many tropical forests are frequently affected by cyclonic disturbance. Consequently, we sampled a beetle assemblage inhabiting 18 upland rainforest sites in a fragmented landscape in north-eastern Queensland, Australia, using a standardised sampling protocol in 2002 and again 12 months after the passage of Severe Tropical Cyclone Larry (March 2006). The spatial configuration of sites allowed us to test if the effects of a cyclone and those from fragmentation interact. From all insect samples we extracted 12,568 beetles of 382 species from ten families. Beetle species composition was significantly different pre-and post-cyclone although the magnitude of faunal change was not large with 205 species, representing 96% of all individuals, present in both sampling events. Sites with the greatest changes to structure had the greatest changes in species composition. At the site level, increases in woody debris and wood-feeding beetle (Scolytinae) counts were significantly correlated but changes in the percent of ground vegetation were not mirrored by changes in the abundance of foliage-feeding beetles (Chrysomelidae). The overall direction of beetle assemblage change was consistent with increasing aridity, presumably caused by the loss of canopy cover. Sites with the greatest canopy loss had the strongest changes in the proportion of species previously identified in the pre-cyclone study as preferring arid or moist rainforest environments. The magnitude of fragmentation effects was virtually unaltered by the passage of Cyclone Larry. We postulate that in the short-term the effects of cyclonic disturbance and forest fragmentation both reduce the extent of moist, interior habitat. PMID:19597849

  17. Thermal stress and tropical cyclones affect economic production in Central America and Caribbean

    NASA Astrophysics Data System (ADS)

    Hsiang, S. M.

    2009-12-01

    Surface temperatures and tropical cyclones have large impacts on economic production. Local cyclone energy dissipation reduces output in agriculture and tourism, while stimulating output in construction. High surface temperatures reduce output in several labor-intensive industries; a 1° C increase for two consecutive years results in production losses of ˜13%. The response is greatest during the hottest season and is non-linear, with high temperature days contributing the most to production losses. The structure of this response matches results from a large ergonomics literature, supporting the hypothesis that thermal stress reduces human performance, driving macroeconomic fluctuations. This large response of non-agricultural sectors suggests that current estimates underestimate the scale and scope of economic vulnerabilities to climate change. Responses of each industry to surface temperature, tropical cyclones and rainfall. Estimates represent the change of value-added in the industry in response to each atmospheric variables during the year of production (L=0) and the years prior (L?1). The responses to surface temperature are triangles, tropical cyclones are squares and rainfall are crosses. Estimates are grey if none of the annual responses are significant at the ? = 0.1 level. Whiskers indicate 95% confidence intervals. Tourism receipts displays the five years prior (L=1-5) because of the long response of that industry to cyclones. Agriculture per worker is also plotted as circles when estimated a second time excluding mainland countries from the sample. Units are: temperature- percent change in output per 0.33°C; cyclones- percent changes in output per 1 standard deviation of tropical cyclone energy; rainfall- percent change in output per 2 cm/month.

  18. Disaster, Deprivation and Death: Large but delayed infant mortality in the wake of Filipino tropical cyclones

    NASA Astrophysics Data System (ADS)

    Anttila-Hughes, J. K.; Hsiang, S. M.

    2011-12-01

    Tropical cyclones are some of the most disastrous and damaging of climate events, and estimates of their destructive potential abound in the natural and social sciences. Nonetheless, there have been few systematic estimates of cyclones' impact on children's health. This is concerning because cyclones leave in their wake a swath of asset losses and economic deprivation, both known to be strong drivers of poor health outcomes among children. In this paper we provide a household-level estimate of the effect of tropical cyclones on infant mortality in the Philippines, a country with one of the most active cyclone climatologies in the world. We reconstruct historical cyclones with detailed spatial and temporal resolution, allowing us to estimate the multi-year effects of cyclones on individuals living in specific locations. We combine the cyclone reconstruction with woman-level fertility and mortality data from four waves of the Filipino Demographic and Health Survey, providing birth histories for over 55,000 women. In multiple regressions that control for year and region fixed effects as well as intra-annual climate variation, we find that there is a pronounced and robust increase in female infant mortality among poor families in the 12-24 months after storms hit. The estimated mortality rate among this demographic subgroup is much larger than official mortality rates reported by the Filipino government immediately after storms, implying that much of a cyclone's human cost arrives well after the storm has passed. We find that high infant mortality rates are associated with declines in poor families' income and expenditures, including consumption of food and medical services, suggesting that the mechanism by which these deaths are effected may be economic deprivation. These results indicate that a major health and welfare impact of storms has been thus far overlooked, but may be easily prevented through appropriately targeted income support policies.

  19. Inter-comparison of extra-tropical cyclone activity in eight reanalysis datasets

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolan L.; Feng, Yang

    2014-05-01

    This study inter-compares extra-tropical cyclone activity in the following eight reanalysis datasets: (1) the Japanese 55-year Reanalysis (JRA55), (2) the Twentieth Century Reanalysis (20CR), (3) the NASA Modern Era Retrospective-analysis for Research and Applications (MERRA), (4) the NCEP Climate Forecast System Reanalysis (CFSR), (5) the ERA-Interim Reanalysis (ERAint), (6) the ERA40 Reanalysis, (7) the NCEP-NCAR Reanalysis (NCEP1), and (8) the NCEP-DOE Reanalysis (NCEP2). The inter-comparison is based on cyclones identified by applying an automatic objective cyclone tracking algorithm to each of the eight datasets. It includes trends and variability in cyclone counts and intensity, as well as track-to-track comparison of cyclones in each pair of these eight datasets. Specifically, MERRA shows higher counts of strong cyclones (of stronger wind force) than the others. CFSR shows many more cyclones of moderate intensity than the others. JRA55 and ERAint are similar in terms of deep cyclone (core pressure ? 980 hPa) statistics in both hemispheres; but JRA55 shows more strong cyclones in the SH than does ERAint. The best track-to-track agreements are between NCEP1~NCEP2, CFSR~ERAint, and ERA40~JRA55 in the NH; and between JRA55~ERA40, JRA55~ERAint, CFSR~ERAint, and CFSR~NCEP2 in the SH. The poorest track-to-track agreements are between 20CR~MERRA in both hemispheres. The best-match tracks are generally those with deeper mean core pressure than the unmatch tracks. In general, there is more similarity in temporal trends and variability than in specific cyclone counts and intensity. This is especially true for deep cyclone counts, which show very good agreement since 1960. There is also more similarity in deep cyclone statistics than in all cyclone statistics. All the eight datasets agree very well on temporal trends and variability of deep cyclone activity over the NH major storm track regions, with some discrepancies in all-cyclone activity in the pre-satellite era. The agreement in temporal trends and variability in the SH is generally not as good as in the NH. In particular, one should note that there exist temporal inhomogeneities in these datasets for both hemispheres, which shall be taken into account when using these datasets to analyze trends.

  20. Tropical Cyclone Bejisa Near Madagascar - Duration: 13 seconds.

    NASA Video Gallery

    NASA's TRMM satellite flew over Cyclone Bejisa on December 29, 2013 at 1507 UTC. This 3-D animation of TRMM data revealed strong thunderstorms around Bejisa's center were reaching heights above 16....

  1. Impacts of different cumulus physics over south Asia region with case study tropical cyclone Viyaru

    E-print Network

    Fahad, Abdullah Al

    2015-01-01

    Tropical Cyclone Viyaru, formerly known as Cyclonic Storm Mahasen was a rapidly intensifying, category 01B storm that made landfall in Chittagong, Bangladesh on the 16th of May, 2013. In this study, the sensitivity of numerical simulations of tropical cyclone to cumulus physics parametrization is carried out with a view to determine the best cumulus physics option for prediction of the cyclones track, timing, and central pressure evolution in the Bay of Bengal. For this purpose, the tropical cyclone Viyaru has been simulated by WRF ARW in a nested domain with NCEP Global Final Analysis(FNL) data as initial and boundary conditions. The model domain consists of one parent domain and one nested domain. The resolution of the parent domain is 36 km while the nested domain has a resolution of 12 km. Five numerical simulations have been done with the same micro-physics scheme (WSM3), planetary boundary layer scheme,NOAH land surface scheme but different Cumulus Parametrization scheme. Four cumulus Parametrization sc...

  2. Tropical Cyclone Motion in Response to Land Surface Friction.

    NASA Astrophysics Data System (ADS)

    Wong, Martin L. M.; Chan, Johnny C. L.

    2006-04-01

    Numerical experiments are performed with the fifth-generation Pennsylvania State University National Center for Atmospheric Research Mesoscale Model (MM5) to study the effects of surface-moisture flux and friction over land on the movement of tropical cyclones (TCs). On an f plane, the TCs are initially placed 150 km due east of a north south-oriented coastline in an atmosphere at rest. It is found that a TC could drift toward land when the roughness length is 0.5 m over land, with an average drift speed of 1 m s-1. Friction, but not surface-moisture flux over land, is apparently essential for the movement toward land. The friction-induced asymmetry in the large-scale flow is the primary mechanism responsible for causing the TC drift. The mechanism responsible for the development of the large-scale asymmetric flow over the lower to midtroposphere (900 600 hPa) appears to be the creation of asymmetric vorticity by the divergence term in the vorticity equation. Horizontal advection then rotates the asymmetric vorticity to give a northeasterly flow in the TC periphery (500 1000 km from the TC center). The flow near the TC center has a more northerly component because of the stronger rotation by the tangential wind of the TC at inner radii. However, the TC does not move with the large-scale asymmetric flow. Potential vorticity budget calculations indicate that while the horizontal advection term is basically due to the effect of advection by the large-scale asymmetric flow, the diabatic heating and vertical advection terms have to be considered in determining the vortex landward drift, because of the strong asymmetry in vertical motion. Two mechanisms could induce the asymmetry in vertical motion and cause a deviation of the TC track from the horizontal asymmetric flow. First, the large-scale asymmetric flow in the upper troposphere differs from that in the lower troposphere, both in magnitude and direction, which results in a vertical shear that could force the asymmetry. A vertical tilt of the vortex axis is also found that is consistent with the direction of shear and also the asymmetry in rainfall and vertical motion. Second, asymmetric boundary layer convergence that results from the internal boundary layer could also force an asymmetry in vertical motion.


  3. Tropical cyclones and the flood hydrology of Puerto Rico

    NASA Astrophysics Data System (ADS)

    Smith, James A.; Sturdevant-Rees, Paula; Baeck, Mary Lynn; Larsen, Matthew C.

    2005-06-01

    Some of the largest unit discharge flood peaks in the stream gaging records of the U.S. Geological Survey (USGS) have occurred in Puerto Rico. Many of these flood peaks are associated with tropical cyclones. Hurricane Georges, which passed directly over the island on 21-22 September 1998, produced record flood peaks at numerous USGS stations in Puerto Rico. The hydrology and hydrometeorology of extreme flood response in Puerto Rico are examined through analyses of rainfall, based on Weather Surveillance Radar-1988 Doppler (WSR-88D) radar reflectivity observations and USGS rain gage observations and discharge from USGS stream gaging stations. Peak rainfall accumulations of more than 700 mm occurred in the central mountain region of the island. The largest unit discharge flood peaks, however, were located in the eastern portion of the island in areas with smaller storm total rainfall accumulations but markedly larger rainfall rates at 5-60 min timescale. Orographic precipitation mechanisms played an important role in rainfall distribution over the island of Puerto Rico. Amplification of rainfall accumulations was associated with areas of upslope motion. Elevated low-level cloud water content in regions of upslope motion played an important role in the maximum rainfall accumulations in the central mountain region of Puerto Rico. The largest unit discharge flood peaks, however, were produced by a decaying eye wall mesovortex, which resulted in a 30-45 min period of extreme rainfall rates over the eastern portion of the island. This storm element was responsible for the record flood peak of the Río Grande de Lóiza. The role of terrain in development and evolution of the eye wall mesovortex is unclear but is of fundamental importance for assessing extreme flood response from the storm. Hydrologic response is examined through analyses of rainfall and discharge from five pairs of drainage basins, extending from east to west over the island. These analyses point to the importance of short-term rainfall rates for extreme flood response. The hydrologic response of Puerto Rico is compared with two other extreme flood environments, the central Appalachians and Edwards Plateau of Texas. These analyses suggest that the high rainfall environment of Puerto Rico is linked to the development of a hydraulically efficient drainage system.

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

    PubMed

    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. PMID:23922393

  5. A Study of Long-lasting Rainbands Associated with Tropical Cyclones in the Western North Pacific

    NASA Astrophysics Data System (ADS)

    Chen, Buo-Fu; Lee, Cheng-Shang

    2013-04-01

    Long-lasting rainbands might occur when tropical cyclones (TCs) interact with the environment, especially the southwest monsoon as in the cases of Typhoons Kalmeagi (2008), Morakot (2009) and Fanapi (2010) in the western North Pacific. These long-lasting rainbands are linear convective systems that have a large cold cloud shield, and last for more than six hours. They often pose great challenges to typhoon rainfall forecast when they interact with terrain to produce continuous torrential rain at remote region of TC. In this study, a total of 165 long-lasting rainbands that occurred to the south of TC centers during 1999-2009 are identified using infrared images and passive micro-wave images. Furthermore, these long-lasting rainbands are classified into two types: outer-MCS (85 cases) and enhanced-rainbands (80 cases), depending on the origin of these rainbands. A long-lasting rainband is classified as outer-MCS if it developed from a distant rainband of the TC. If the long-lasting rainband is a primary rainband, it is classified as enhanced-rainband. Results show that 31% of all TCs in the western North Pacific produce at least one long-lasting rainband during its life period. An outer-MCS generally occurs at area 200-700 km away from the TC center and moves usually outward with respect to the moving TC center. It often develops in the downshear right quadrant of a TC. On the other hand, an enhanced-rainband usually is distributed between 100- and 300-km radii of a TC and moves cyclonically. It often develops in the downshear left quadrant of a TC. The environmental conditions favorable for the development of long-lasting rainbands are identified, including low-level south-westerly flows, mid-level dry air associated with the subtropical high, and strong vertical wind shears. Results also show that impacts of outer-MCS and that of enhanced-rainbands on TC structure changes are quite different. When an enhanced-rainband occurs, the TC usually increases its size with a faster rate and the intensification rate remains the same. However, the increasing rate of size remains the same but the intensification rate becomes slower when an outer-MCS occurs.

  6. Australian tropical cyclone activity lower than at any time over the past 550-1,500 years.

    PubMed

    Haig, Jordahna; Nott, Jonathan; Reichart, Gert-Jan

    2014-01-30

    The assessment of changes in tropical cyclone activity within the context of anthropogenically influenced climate change has been limited by the short temporal resolution of the instrumental tropical cyclone record (less than 50 years). Furthermore, controversy exists regarding the robustness of the observational record, especially before 1990. Here we show, on the basis of a new tropical cyclone activity index (CAI), that the present low levels of storm activity on the mid west and northeast coasts of Australia are unprecedented over the past 550 to 1,500 years. The CAI allows for a direct comparison between the modern instrumental record and long-term palaeotempest (prehistoric tropical cyclone) records derived from the (18)O/(16)O ratio of seasonally accreting carbonate layers of actively growing stalagmites. Our results reveal a repeated multicentennial cycle of tropical cyclone activity, the most recent of which commenced around AD?1700. The present cycle includes a sharp decrease in activity after 1960 in Western Australia. This is in contrast to the increasing frequency and destructiveness of Northern Hemisphere tropical cyclones since 1970 in the Atlantic Ocean and the western North Pacific Ocean. Other studies project a decrease in the frequency of tropical cyclones towards the end of the twenty-first century in the southwest Pacific, southern Indian and Australian regions. Our results, although based on a limited record, suggest that this may be occurring much earlier than expected. PMID:24476890

  7. Self-Stratification of Tropical Cyclone Outflow. Part I: Implications for Storm Structure

    E-print Network

    Rothman, Daniel

    Self-Stratification of Tropical Cyclone Outflow. Part I: Implications for Storm Structure KERRY of the outflow occurs below the ambient tropopause and develops its own stratification, unrelated to that of the unperturbed environment. The authors propose that this stratification is set in the storm's core

  8. Cluster analysis of tropical cyclone tracks in the Southern Hamish A. Ramsay Suzana J. Camargo

    E-print Network

    Cluster analysis of tropical cyclone tracks in the Southern Hemisphere Hamish A. Ramsay · Suzana J 2011 Ó Springer-Verlag 2011 Abstract A probabilistic clustering method is used to describe various clusters are examined: three in the South Indian Ocean, three in the Australian Region, and one

  9. RETRIEVAL OF HYDROMETEOR PROFILES IN TROPICAL CYCLONES AND CONVECTION BY A COMBINED

    E-print Network

    Jiang, Haiyan

    ocean from combined spaceborne radar and radiometer measurements. In the algorithm, the interceptCHAPTER 3 RETRIEVAL OF HYDROMETEOR PROFILES IN TROPICAL CYCLONES AND CONVECTION BY A COMBINED RADAR radar reflectivity profile are used to obtain LWC and IWC profiles. 0N bT 0N The retrieval technique

  10. Contribution of tropical cyclones to extreme rainfall events in the southeastern United States

    Microsoft Academic Search

    David B. Knight; Robert E. Davis

    2009-01-01

    Extreme precipitation has been increasing in the United States over the past century. In light of the associated impacts and possible linkages to climate change, this topic has garnered a great deal of attention from the scientific community and general public. Because tropical cyclones are a common source of heavy rainfall in the southeastern United States, we examined the contribution

  11. Tree-ring isotope records of tropical cyclone activity Dana L. Miller*, Claudia I. Mora*

    E-print Network

    Grissino-Mayer, Henri D.

    Tree-ring isotope records of tropical cyclone activity Dana L. Miller*, Claudia I. Mora* , Henri D a 220- year record of oxygen isotope values of -cellulose in longleaf pine tree rings that preserves anomalously low isotope values in the latewood portion of the ring in years corresponding with known 19th

  12. Clustering of eastern North Pacific tropical cyclone tracks: ENSO and MJO effects

    Microsoft Academic Search

    Suzana J. Camargo; Andrew W. Robertson; Anthony G. Barnston; Michael Ghil

    2008-01-01

    A probabilistic clustering technique is used to describe tropical cyclone tracks in the eastern North Pacific, on the basis of their shape and location. The best track data set is decomposed in terms of three clusters; these clusters are analyzed in terms of genesis location, trajectory, landfall, intensity, seasonality, and their relationships with the El Niño–Southern Oscillation (ENSO) and Madden-Julian

  13. Warm ocean anomaly, air sea fluxes, and the rapid intensification of tropical cyclone Nargis (2008)

    E-print Network

    Texas at Austin. University of

    2008-01-01

    Warm ocean anomaly, air sea fluxes, and the rapid intensification of tropical cyclone Nargis (2008. Using in situ ocean depth-temperature measurements and satellite altimetry, it is found that Nargis' rapid intensification took place on a pre-existing warm ocean anomaly in the Bay of Bengal

  14. Modeling the Direct and Indirect Effects of Atmospheric Aerosols on Tropical Cyclones

    E-print Network

    Lee, Keun-Hee

    2012-02-14

    Pa wind within an annulus starting at 100 km and extending to 300 km from the center of the hurricane [Knaff et al., 2004]. It has been recognized that the vertical wind shear tends to give a negative influence on tropical cyclone development [Emmanuel...

  15. The effects of Cyclone Waka on the structure of lowland tropical rain forest in Vavau, Tonga

    Microsoft Academic Search

    Janet Franklin; Donald R. Drake; Kim R. McConkey; Filipe Tonga; Leslie B. Smith

    2004-01-01

    On 31 December 2001, Tropical Cyclone Waka passed directly over the Vava'u island group, Kingdom of Tonga, with sustained and maximum wind speeds of 185 km h?1 and 230 km h?1 respectively. During a prior study of forest secondary succession, 44 forest plots on 13 islands had been surveyed in 1995 and their locations marked. Nineteen of the plots were

  16. Understanding and Forecasting Tropical Cyclone Intensity Change with the Typhoon Intensity Prediction Scheme (TIPS)

    Microsoft Academic Search

    Patrick J. Fitzpatrick

    1997-01-01

    A multiple regression scheme with tropical cyclone intensity change as the dependent variable has been developed. The new scheme is titled the Typhoon Intensity Prediction Scheme (TIPS) and is similar to one used operationally at the National Hurricane Center. However, TIPS contains two major differences: it is developed for the western North Pacific Ocean, and utilizes digitized satellite data; the

  17. On the Height of the Warm Core in Tropical Cyclones DANIEL P. STERN

    E-print Network

    Nolan, David S.

    On the Height of the Warm Core in Tropical Cyclones DANIEL P. STERN Department of Meteorology not well known. In the control simulation, the height of the warm core is nearly constant over a wide range based on thermal wind balance, it is shown that the height of the warm core is not necessarily related

  18. Tropical Cyclone Genesis Factors in Simulations of the Last Glacial Maximum ROBERT L. KORTY

    E-print Network

    and examined in simu- lations of the Last Glacial Maximum (LGM) from the Paleoclimate Modelling Intercomparison Project Phase 2 (PMIP2). Despite universally colder conditions at the LGM, values of tropical cyclone Pacific, feature higher po- tential intensities at the LGM than they do in the control runs, while other

  19. An Estimate of North Atlantic Basin Tropical Cyclone Activity for 2008

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2008-01-01

    The statistics of North Atlantic basin tropical cyclones for the interval 1945-2007 are examined and estimates are given for the frequencies of occurrence of the number of tropical cyclones, number of hurricanes, number of major hurricanes, number of category 4/5 hurricanes, and number of U.S. land-falling hurricanes for the 2008 hurricane season. Also examined are the variations of peak wind speed, average peak wind speed per storm, lowest pressure, average lowest pressure per storm, recurrence rate and duration of extreme events (El Nino and La Nina), the variation of 10-yr moving averages of parametric first differences, and the association of decadal averages of frequencies of occurrence of North Atlantic basin tropical cyclones against decadal averages of Armagh Observatory, Northern Ireland, annual mean temperature (found to be extremely important for number of tropical cyclones and number of hurricanes). Because the 2008 hurricane season seems destined to be one that is non-El Nino-related and is a post-1995 season, estimates of the frequencies of occurrence for the various subsets of storms should be above long-term averages.

  20. meeting summary: Third COMPARE Workshop: A Model Intercomparison Experiment of Tropical Cyclone Intensity and Track Prediction

    Microsoft Academic Search

    Masashi Nagata; Lance Leslie; Yoshio Kurihara; Russell L. Elsberry; Masanori Yamasaki; Hirotaka Kamahori; Robert Abbey Jr.; Kotaro Bessho; Javier Calvo; Johnny C. L. Chan; Peter Clark; Michel Desgagne; Song-You Hong; Detlev Majewski; Piero Malguzzi; John McGregor; Hiroshi Mino; Akihiko Murata; Jason Nachamkin; Michel Roch; Clive Wilson

    2001-01-01

    The Third Comparison of Mesoscale Prediction and Research Experiment (COMPARE) workshop was held in Tokyo, Japan, on 13-15 December 1999, cosponsored by the Japan Meteorological Agency (JMA), Japan Science and Technology Agency, and the World Meteorological Organization. The third case of COMPARE focuses on an event of explosive tropical cyclone [Typhoon Flo (9019)] development that occurred during the cooperative three

  1. Pattern Classification of Tropical Cyclone Tracks over the Western North Pacific using a Fuzzy Clustering Method

    Microsoft Academic Search

    H. Kim; C. Ho; J. Kim

    2008-01-01

    This study presents the pattern classification of tropical cyclone (TC) tracks over the western North Pacific (WNP) basin during the typhoon season (June through October) for 1965-2006 (total 42 years) using a fuzzy clustering method. After the fuzzy c-mean clustering algorithm to the TC trajectory interpolated into 20 segments of equivalent length, we divided the whole tracks into 7 patterns.

  2. Optimal Rain Rate Estimation in Tropical Cyclones: Validation of Sfmr Remote Sensing Rain Rates

    Microsoft Academic Search

    H. Jiang; P. G. Black; E. W. Uhlhorn; P. A. Leighton; E. J. Zipser; F. D. Marks

    2002-01-01

    Rain rates within tropical cyclones obtained from the Stepped Frequency Microwave Radiometer (SFMR) on the NOAA WP-3D hurricane research aircraft are analyzed and validated. Airborne radar and particle image data from the same flights are interpolated or averaged into 12-s time intervals for comparing with SFMR data. Also, airborne radar data are used to categorize the SFMR data according to

  3. Wind Farms in Regions Exposed to Tropical Cyclones Niels-Erik Clausen1

    E-print Network

    with tropical cyclones. Present international design codes for wind turbines do not apply to these regions. A 30 MW wind farm located at the north-east of the Philippines is considered as the case study safety factor is 1.35. The wind turbine yawing controls were found to be able to cope with the demands

  4. The air-sea interface and surface stress under tropical cyclones.

    PubMed

    Soloviev, Alexander V; Lukas, Roger; Donelan, Mark A; Haus, Brian K; Ginis, Isaac

    2014-01-01

    Tropical cyclone track prediction is steadily improving, while storm intensity prediction has seen little progress in the last quarter century. Important physics are not yet well understood and implemented in tropical cyclone forecast models. Missing and unresolved physics, especially at the air-sea interface, are among the factors limiting storm predictions. In a laboratory experiment and coordinated numerical simulation, conducted in this work, the microstructure of the air-water interface under hurricane force wind resembled Kelvin-Helmholtz shear instability between fluids with a large density difference. Supported by these observations, we bring forth the concept that the resulting two-phase environment suppresses short gravity-capillary waves and alters the aerodynamic properties of the sea surface. The unified wave-form and two-phase parameterization model shows the well-known increase of the drag coefficient (Cd) with wind speed, up to ~30 ms(-1). Around 60 ms(-1), the new parameterization predicts a local peak of Ck/Cd, under constant enthalpy exchange coefficient Ck. This peak may explain rapid intensification of some storms to major tropical cyclones and the previously reported local peak of lifetime maximum intensity (bimodal distribution) in the best-track records. The bimodal distribution of maximum lifetime intensity, however, can also be explained by environmental parameters of tropical cyclones alone. PMID:24930493

  5. A WSR-88D Assessment of Tropical Cyclone Outer Rainband Tornadoes

    Microsoft Academic Search

    Scott M. Spratt; David W. Sharp; Pat Welsh; Al Sandrik; Frank Alsheimer; Charlie Paxton

    1997-01-01

    As part of the National Weather Service (NWS) Modernization and Restructuring Program, WSR-88D (NE- XRAD) Doppler radar installation has been completed at each Weather Service Office in Florida. Recently, this powerful new tool provided unique opportunities for Jacksonville, Tampa Bay, and Melbourne NEXRAD Weather Service Office personnel to investigate tropical cyclone (TC) rainbands for evidence of tornadogenesis. This study provides

  6. Sea Surface Temperature and the Maximum Intensity of Atlantic Tropical Cyclones

    Microsoft Academic Search

    Mark Demaria; John Kaplan

    1994-01-01

    An empirical relationship between climatological sea surface temperature (SST) and the maximum intensity of tropical cyclones in the North Atlantic basin is developed from a 31-year sample (1962-1992). This relationship is compared with the theoretical results described by Emanuel. The theoretical results are in agreement with the observations over a wide range of SST, provided that the tropopause temperature is

  7. Current understanding of tropical cyclone structure and intensity changes – a review

    Microsoft Academic Search

    Y. Wang; C.-C. Wu

    2004-01-01

    Summary Current understanding of tropical cyclone (TC) structure and intensity changes has been reviewed in this article. Recent studies in this area tend to focus on two issues: (1) what factors determine the maximum potential intensity (MPI) that a TC can achieve given the thermodynamic state of the atmosphere and the ocean? and (2) what factors prevent the TCs from

  8. An explicit three-dimensional nonhydrostatic numerical simulation of a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Tripoli, G. J.

    1992-01-01

    A nonhydrostatic numerical simulation of a tropical cyclone is performed with explicit representation of cumulus on a meso-beta scale grid and for a brief period on a meso-gamma scale grid. Individual cumulus plumes are represented by a combination of explicit resolution and a 1.5 level closure predicting turbulent kinetic energy (TKE).

  9. The air-sea interface and surface stress under tropical cyclones

    PubMed Central

    Soloviev, Alexander V.; Lukas, Roger; Donelan, Mark A.; Haus, Brian K.; Ginis, Isaac

    2014-01-01

    Tropical cyclone track prediction is steadily improving, while storm intensity prediction has seen little progress in the last quarter century. Important physics are not yet well understood and implemented in tropical cyclone forecast models. Missing and unresolved physics, especially at the air-sea interface, are among the factors limiting storm predictions. In a laboratory experiment and coordinated numerical simulation, conducted in this work, the microstructure of the air-water interface under hurricane force wind resembled Kelvin-Helmholtz shear instability between fluids with a large density difference. Supported by these observations, we bring forth the concept that the resulting two-phase environment suppresses short gravity-capillary waves and alters the aerodynamic properties of the sea surface. The unified wave-form and two-phase parameterization model shows the well-known increase of the drag coefficient (Cd) with wind speed, up to ~30?ms?1. Around 60?ms?1, the new parameterization predicts a local peak of Ck/Cd, under constant enthalpy exchange coefficient Ck. This peak may explain rapid intensification of some storms to major tropical cyclones and the previously reported local peak of lifetime maximum intensity (bimodal distribution) in the best-track records. The bimodal distribution of maximum lifetime intensity, however, can also be explained by environmental parameters of tropical cyclones alone. PMID:24930493

  10. Trend discrepancies among three best track data sets of western North Pacific tropical cyclones

    NASA Astrophysics Data System (ADS)

    Song, Jin-Jie; Wang, Yuan; Wu, Liguang

    2010-06-01

    The hot debate over the influence of global warming on tropical cyclone (TC) activity in the western North Pacific over the past several decades is partly due to the diversity of TC data sets used in recent publications. This study investigates differences of track, intensity, frequency, and the associated long-term trends for those TCs that were simultaneously recorded by the best track data sets of the Joint Typhoon Warning Center (JTWC), the Regional Specialized Meteorological Center (RSMC) Tokyo, and the Shanghai Typhoon Institute (STI). Though the differences in TC tracks among these data sets are negligibly small, the JTWC data set tends to classify TCs of category 2-3 as category 4-5, leading to an upward trend in the annual frequency of category 4-5 TCs and the annual accumulated power dissipation index, as reported by Webster et al. (2005) and Emanuel (2005). This trend and potential destructiveness over the period 1977-2007 are found only with the JTWC data set, but downward trends are apparent in the RSMC and STI data sets. It is concluded that the different algorithms used in determining TC intensity may cause the trend discrepancies of TC activity in the western North Pacific.

  11. Potential Application of Airborne Passive Microwave Observations for Monitoring Inland Flooding Caused by Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Radley, C.D.; LaFontaine, F.J.

    2008-01-01

    Inland flooding from tropical cyclones can be a significant factor in storm-related deaths in the United States and other countries. Information collected during NASA tropical cyclone field studies suggest surface water and flooding induced by tropical cyclone precipitation can be detected and therefore monitored using passive microwave airborne radiometers. In particular, the 10.7 GHz frequency of the NASA Advanced Microwave Precipitation Radiometer (AMPR) flown on the NASA ER-2 has demonstrated high resolution detection of anomalous surface water and flooding in numerous situations. This presentation will highlight the analysis of three cases utilizing primarily satellite and airborne radiometer data. Radiometer data from the 1998 Third Convection and Moisture Experiment (CAMEX-3) are utilized to detect surface water during landfalling Hurricane Georges in both the Dominican Republic and Louisiana. A third case is landfalling Tropical Storm Gert in Eastern Mexico during the Tropical Cloud Systems and Processes (TCSP) experiment in 2005. AMPR data are compared to topographic data and vegetation indices to evaluate the significance of the surface water signature visible in the 10.7 GHz information. The results of this study suggest the benefit of an aircraft 10 GHz radiometer to provide real-time observations of surface water conditions as part of a multi-sensor flood monitoring network.

  12. Tropical cyclone rainfall characteristics as determined from a satellite passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Rodgers, E. B.; Adler, R. F.

    1981-01-01

    Data from the Nimbus 5 electrically scanning microwave radiometer (ESMR-5) were used to calculate latent heat release (LHR) and other rainfall parameters for over 70 satellite observations of 21 tropical cyclones during 1973, 1974, and 1975 in the tropical North Pacific Ocean. The results indicate that the ESMR-5 measurements can be useful in determining the rainfall characteristics of these storms and appear to be potentially useful in monitoring as well as predicting their intensity. The ESMR-5 derived total tropical cyclone rainfall estimates agree favorably with previous estimates for both the disturbance and typhoon stages. The mean typhoon rainfall rate (1.9 mm h/1) is approximately twice that of disturbances (1.1 mm h/1).

  13. Biological response due to tropical cyclone PHYN in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Rao Neerukattu, Srinivasa; Rao, B. Venkateswara

    During the fall intermonsoon cyclone PHYN (09-11 Nov 2009) occurred in the Northeast Ara-bian Sea, we observed 4.4 C mean Sea Surface Temperature (SST) drop in Aqua-MODIS derived SST data; where the maximum wind speeds recorded were of the order of 50 Knots. High wind speeds deepened the vertical mixing of 90 m, and brought the cold (23.9C), nutrient rich waters to the surface; this is confirmed with Argo's temperature profile data. Post cyclone chlorophyll-a (Chl-a) enhancement was observed through 8 day mean average chlorophyll-a derived from Aqua-MODIS data, concentration from 4.56 mg/m3 to 16 mg/m3. SST drop and Chl-a Enhancement are not continuum all along the cyclone path; Maximum SST drop and Chl-a enhancement are observed at the establishment of `cyclone eye'. The formation of an eye is almost always an indicator of increasing tropical cyclone organization and strength. Where the cyclone stalls, its movement has fallen below 2.24m/s, movement is erratic over a small area; the wave action caused by the strong surface winds churns the ocean surface and produces upwelling. This has the effect of cooling the temperature of the sea surface over an area 200 to 300 miles across. Strong asymmetry in the SST response occurs in the wake of the storm. These results in a cool swath of SST centered 50-400 km on the right hand side of the storm track. SST drop 3o C larger than on left hand side of the track. Tropical cyclones when passing over land may have destroying human lives, but over the ocean they can strongly enhance biological life i.e. enhancing phytoplankton (Chl-a) biomass.

  14. Stable isotope anatomy of tropical cyclone Ita, North-Eastern Australia, April 2014.

    PubMed

    Munksgaard, Niels C; Zwart, Costijn; Kurita, Naoyuki; Bass, Adrian; Nott, Jon; Bird, Michael I

    2015-01-01

    The isotope signatures registered in speleothems during tropical cyclones (TC) provides information about the frequency and intensity of past TCs but the precise relationship between isotopic composition and the meteorology of TCs remain uncertain. Here we present continuous ?18O and ?2H data in rainfall and water vapour, as well as in discrete rainfall samples, during the passage of TC Ita and relate the evolution in isotopic compositions to local and synoptic scale meteorological observations. High-resolution data revealed a close relationship between isotopic compositions and cyclonic features such as spiral rainbands, periods of stratiform rainfall and the arrival of subtropical and tropical air masses with changing oceanic and continental moisture sources. The isotopic compositions in discrete rainfall samples were remarkably constant along the ~450 km overland path of the cyclone when taking into account the direction and distance to the eye of the cyclone at each sampling time. Near simultaneous variations in ?18O and ?2H values in rainfall and vapour and a near-equilibrium rainfall-vapour isotope fractionation indicates strong isotopic exchange between rainfall and surface inflow of vapour during the approach of the cyclone. In contrast, after the passage of spiral rainbands close to the eye of the cyclone, different moisture sources for rainfall and vapour are reflected in diverging d-excess values. High-resolution isotope studies of modern TCs refine the interpretation of stable isotope signatures found in speleothems and other paleo archives and should aim to further investigate the influence of cyclone intensity and longevity on the isotopic composition of associated rainfall. PMID:25742628

  15. Lightning activity within tropical cyclones in the South West Indian Ocean

    NASA Astrophysics Data System (ADS)

    Bovalo, C.; Barthe, C.; Yu, N.; Bègue, N.

    2014-07-01

    Lightning activity within 70 tropical cyclones in the South West Indian Ocean is studied using a large data set (2005-2013) provided by the World Wide Lightning Location Network (WWLLN). The radial and azimuthal distributions of lightning flashes are analyzed in three different regions of the basin: the open ocean, the Mozambique Channel, and the oceanic region up to 400 km off the eastern coast of Madagascar (ECM). Over the open ocean, lightning activity detected by the WWLLN is mainly found in the eyewall and decreases outward, regardless of storm intensity. Lightning activity in the eyewall of tropical cyclones is higher than in the eyewall of tropical storms. The front and the right quadrants (225° to 45°) relative to the storm motion are the regions where lightning flashes are preferentially detected. Near the ECM, lightning density in the eyewall, the inner rainbands, and the outer rainbands is quite similar, presumably owing to the proximity of land. When the system reaches tropical cyclone strength, lightning activity is mainly found in the left and rear quadrants relative to storm motion. In the Mozambique Channel, the radial and azimuthal distributions of lightning flashes are complex due to the geographical configuration of this subdomain. The relationships between lightning activity and intensity change have also been investigated for systems over the open ocean. The proportion of periods with lightning activity is higher during rapid intensity changes of tropical cyclones. During tropical storm stage, lightning activity in the outer rainbands starts increasing 18 h before a rapid intensification period. 2014. American Geophysical Union. All Rights Reserved.

  16. An Observing System Simulation Experiment for the use of Unmanned Aircraft Systems in improving tropical cyclone forecasts

    NASA Astrophysics Data System (ADS)

    Prive, N.; Xie, Y.; Koch, S. E.; Atlas, R.; Majumdar, S.; Masutani, M.; Woollen, J.; Riishojgaard, L.

    2010-12-01

    Unmanned Aircraft Systems (UAS) are capable of providing in situ observations in tropical cyclones which are not possible by other means. An Observing System Simulation Experiment (OSSE) is performed to evaluate the potential use of UAS for improving the analysis and forecasting of tropical cyclones in the Atlantic basin. The OSSE framework allows many different data sampling strategies to be tested, revealing how the new observations interact with the data assimilation system. In this OSSE, the Global Forecast System and Gridpoint Statistical Interpolation data assimilation package are used as the experimental forecast model, with Nature Run from the European Centre for Medium-range Weather Forecasts. Improvements in the 3-5 day tropical cyclone track forecasts are seen when tropical cyclones are observed by a high-altitude UAS with dropsonde deployment. The potential use of OSSEs for addressing theoretical aspects of data assimilation and new observing systems will be discussed.

  17. Salt Content and Oxygen Isotope Ratios of Rain as Indices of Tropical Cyclone Intensification

    NASA Astrophysics Data System (ADS)

    Lawrence, J. R.; Gedzelman, S. D.; Padilla, H.

    2006-12-01

    Tropical cyclones making landfall in the United States exhibit large variations in both their concentrations of salt and oxygen isotope ratios. For most storms chloride concentrations (3.5 to 11 ppm) fell in the same range as those of average coastal rainfall. For two storms, Georges 98 and Katrina 05, the chloride concentrations were 25 and 50 ppm respectively. Mean oxygen isotope values ranged from -5.3 to -11.2 per mil for all storms with George 98 and Katrina 05, having oxygen isotope values of -7.4 and -4.6 per mil. The concentration of chloride in the storms is the direct result of the addition of sea spray or salt particles from sea spray into the storm with subsequent removal by rainout. Oxygen isotope values of tropical cyclones have been shown to decrease from the outer edges of the storm toward the center as the result of exposure of inflowing water vapor to rain with low isotope values. A subsequent rise in the innermost regions of the storm suggests that increased sea spray plays a roll. The oxygen isotope value of seawater is 0 per mil. Simple mass balance considerations using Katrina 05 as an example show that the high mean oxygen isotope value of the rain from Katrina where collections were made in the interior most region of the storm cannot be explained by the simple addition of sea spray to the rain. Rather the oxygen isotopic composition of the water vapor in the innermost portions of intense tropical cyclones must be relatively high because of the high degree of evaporation of sea spray droplets and the high rate of isotopic exchange due to the increased surface area of liquid water. This water vapor having a high oxygen isotope value must be a major source of water for the inner portions of intense tropical cyclones. The thermodynamics of this process is a key to understanding the intensification of intense tropical cyclones. The combined study of salt concentrations, of stable isotope ratios and the use of trajectory analysis in tropical cyclones promises to be a powerful tool in unraveling the secrets of rapid storm intensification.

  18. A weather analysis system for Baja California: tropical cyclone season of 2006

    NASA Astrophysics Data System (ADS)

    Farfan, L. M.

    2007-05-01

    During the warm season of 2006, general characteristics of tropical weather systems were documented on a real-time basis. This study covered the period July-October and included an analysis of observations derived from a regional network: imagery from radar and geostationary satellite, and data from surface stations. A set of graphical products were generated and were available to a broad audience by using the internet address http:met-bcs.cicese.mx. Products were updated anywhere from one to 24 hours and included displays from numerical models. The analysis system has been in operation since the summer of 2005 and it is concentrated in the development of eastern Pacific tropical cyclones. In 2006 this basin had 18 tropical storms and 10 hurricanes, which are slightly above the corresponding normals. Three cyclones (John, Lane, and Paul) made landfall on the northwest coast of Mexico and four other systems developed within 800 km from the area of interest, resulting in additional events of convective activity over southern Baja California. This presentation is intended to provide a summary of the tropical cyclone activity, lessons learned from the application of the analysis system, and plans for the upcoming season of 2007.

  19. The relationship between satellite measured convective bursts and tropical cyclone intensification

    NASA Technical Reports Server (NTRS)

    Steranka, J.; Rodgers, E. B.; Gentry, R. C.

    1986-01-01

    High temporal resolution satellite IR measurements are used to analyze the relationship between the mean temperature of cloud canopy tops and the future maximum winds of Atlantic Ocean tropical cyclones. The measurements showed that prolonged surges of intense convection developed in the rear region surrounding cyclone depression centers before the maximum winds initially increased. When surges lasted for 9 hr or more, and the cloud-top temperature within 222 km of the cyclone centers was 238 K or less, then 71 percent of the time the maximum winds increased by 5 m/s or more within 24 hr. When intense convection was not present, similar maximum wind increases occurred only 37 percent of the time.

  20. Predicting tropical cyclone intensity using satellite-measured equivalent blackbody temperatures of cloud tops

    NASA Technical Reports Server (NTRS)

    Gentry, R. C.; Rodgers, E.; Shenk, W. E.; Steranka, J.

    1980-01-01

    A relationship between maximum winds and satellite-measured equivalent blackbody temperatures near tropical cyclones is investigated with data from both the Atlantic and western North Pacific areas. This investigation revealed not only a significant correlation between satellite-derived equivalent blackbody temperatures and maximum winds but also a strong lag relationship between these temperatures and maximum winds. From this latter relationship a regression technique was developed to forecast 24-h changes of the maximum winds for weak (maximum winds less than or equal to 65 kt) and strong (maximum winds greater than 65 kt) tropical cyclones by utilizing the equivalent blackbody temperatures around the storm alone, together with changes in maximum winds during the preceding 24 h and the current maximum winds. Testing of these equations with independent data showed that the mean errors of forecasts made by the equations are lower than the errors in forecasts made by persistence techniques.

  1. Clustering of eastern North Pacific tropical cyclone tracks: ENSO and MJO eects

    Microsoft Academic Search

    Suzana J. Camargo; Andrew W. Robertson; Anthony G. Barnston; Michael Ghil

    A probabilistic clustering technique is used to describe tropical cyclone tracks in the eastern North Pacific, based on their shape and location. The best-track dataset is decomposed in terms of three clusters; these clusters are analyzed in terms of gene- sis location, trajectory, landfall, intensity, seasonality, and their relationships with the El Nino-Southern Oscillation (ENSO) and Madden-Julian Oscillation (MJO). Longitudinal

  2. Lightning Observations During Tropical Cyclone Intensity Change: A Composite Study of Spatial and Temporal Relationships

    Microsoft Academic Search

    Marcus Austin

    2010-01-01

    Although tropical cyclone (TC) track forecasts have improved considerably in recent years, predicting their intensity continues to be a challenge for both meteorologists and numerical models. A storm’s path is primarily influenced greatly by large-scale atmospheric circulations; however, its strength appears to be dominated both by large scale influences and small-scale mechanisms within the storm itself. Most previous research on

  3. Upper-Level Eddy Angular Momentum Fluxes and Tropical Cyclone Intensity Change

    Microsoft Academic Search

    Mark Demaria; Jong-Jin Baik; John Kaplan

    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 (371 synoptic times). A period of enhanced EFC within 1500 km of the storm center occurred about every 5 days due to the interaction with upper-level troughs in the midlatitude westerlies or upper-level, cold lows

  4. On sea surface roughness parameterization and its effect on tropical cyclone structure and intensity

    Microsoft Academic Search

    Zhihua Zeng; Yuqing Wang; Yihong Duan; Lianshou Chen; Zhiqiu Gao

    2010-01-01

    A new parameterization scheme of sea surface momentum roughness length for all wind regimes, including high winds, under tropical\\u000a cyclone (TC) conditions is constructed based on measurements from Global Positioning System (GPS) dropsonde. It reproduces\\u000a the observed regime transition, namely, an increase of the drag coefficient with an increase in wind speed up to 40 m s?1, followed by a

  5. Seasonal Rates for Atlantic Basin Tropical Cyclones During the Present Epoch

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Ten-year moving averages of the seasonal rates for "named storms," tropical storms, hurricanes, and major (or intense) hurricanes in the Atlantic basin since 1950 suggest that the present epoch is one of enhanced activity. Consequently, the outlook for the 2001 hurricane season and immediately succeeding seasons is for all categories of Atlantic basin tropical cyclones to have seasonal rates at levels equal to or above their long-term median rates, especially when the season is designated non-El Nino-related. Only when the season is designated El Nino-related does it appear likely that seasonal rates might be slightly diminished.

  6. A complete tropical cyclone radial wind structure model and comprehensive comparison with observations

    NASA Astrophysics Data System (ADS)

    Chavas, D. R.; Emanuel, K.; Lin, N.

    2014-12-01

    This work develops a simple model for the complete radial structure of the tropical cyclone wind field at the top of the boundary layer. The model is constructed by mathematically merging existing theoretical solutions for the radial wind structure in the inner convecting and outer non-convecting regions. The model is then evaluated against three observational datasets. First, the outer solution is tested against a global database from the QuikSCAT satellite (1999-2009) and found to reproduce the characteristic wind structure of tropical cyclones at large radii where convection is absent, suggesting that it successfully captures the physics of this region. Second, the inner solution is tested against the HWind database (2004-2012) for the Atlantic and East Pacific basins and are shown to credibly represent the inner-core structure but substantially underestimate wind speeds at large radii. The complete model is then shown to largely rectify this underestimation, particularly at higher intensities. Finally, model variability is compared with the Extended Best Track dataset (1988-2013). The complete model exhibits two modes of variability corresponding to the independent variations in storm size and in inner structure that mirror that observed in nature, including the independent variability of the inner and outer regions of tropical cyclones. More broadly, the model provides insight into clear definitions of the terms "size" and "structure" and their respective, independent variabilities.

  7. Impact of aerosols on tropical cyclones: An investigation using convection-permitting model simulation

    NASA Astrophysics Data System (ADS)

    Hazra, Anupam; Mukhopadhyay, P.; Taraphdar, S.; Chen, J.-P.; Cotton, William R.

    2013-07-01

    role of aerosols' effect on two tropical cyclones over the Bay of Bengal is investigated using a convection-permitting model with a two-moment mixed-phase bulk cloud microphysics scheme. The simulation results show the role of aerosol on the microphysical and dynamical properties of the cloud and bring out the change in efficiency of the clouds in producing precipitation. The tracks of the tropical cyclones (TCs) are hardly affected by the changing aerosol concentrations, but the intensity exhibits significant sensitivity due to the change in aerosol concentration. It is also clearly seen from the analyses that higher heating in the middle troposphere within the cyclone center is in response to latent heat release as a consequence of greater graupel formation. Greater heating in the middle level is particularly noticeable for the clean aerosol regime which causes enhanced divergence in the upper level, which, in turn, forces lower level convergence. As a result, the cleaner aerosol perturbation is more unstable within the cyclone core and produces a more intense cyclone as compared to the other two aerosol perturbations. This study, along with previous simulations, shows the robustness of the concept of TC weakening by storm ingestion of high concentrations of cloud condensation nuclei (CCN). The consistency of these model results gives us confidence in stating that there is a high probability that ingestion of high CCN concentrations in a TC will lead to weakening of the storm but has little impact on storm direction. Moreover, as pollution is increasing over the Indian subcontinent, this study suggests that pollution may be weakening TCs over the Bay of Bengal.

  8. Large-scale factors in tropical and extratropical cyclone transition and extreme weather events.

    PubMed

    Pezza, Alexandre Bernardes; Simmonds, Ian

    2008-12-01

    Transition mechanisms characterizing changes from hurricanes to midlatitude cyclones and vice-versa (extratropical and tropical transition) have become a topic of increasing interest, partially because of their association with recent unusual storms that have developed in different ocean basins of both hemispheres. The aim of this work is to discuss some recent cases of transition and highly unusual hurricane developments and to address some of their wider implications for climate science. Frequently those dramatic cyclones are responsible for severe weather, potentially causing significant damage to property and infrastructure. An additional manifestation discussed here is their association with cold surges, a topic that has been very little explored in the literature. In the Southern Hemisphere, the first South Atlantic hurricane, Catarina, developed in March 2004 under very unusual large-scale conditions. That exceptional cyclone is viewed as a case of tropical transition facilitated by a well-developed blocking structure. A new index for monitoring tropical transition in the subtropical South Atlantic is discussed. This "South Atlantic index" is used to show that the unusual flow during and prior to Catarina's genesis can be attributed to tropical/extratropical interaction mechanisms. The "Donald Duck" case in Australia and Vince in the North Atlantic have also been examined and shown to belong to a category of hybrid-transitioning systems that will achieve at least partial tropical transition. While clearly more research is needed on the topic of transition, as we gain further insight, it is becoming increasingly apparent that features of large-scale circulation do play a fundamental role. A complex interaction between an extratropical transition case and an extreme summer cold surge affecting southeastern Australia is discussed as an example of wider climate implications. PMID:19076416

  9. Tropical Cyclone Intensification from Asymmetric Convection: Energetics and Efficiency

    E-print Network

    Nolan, David S.

    perturbations to represent rapid heat release in cumulus updrafts. Purely asymmetric heat sources that evolve. A sense of these heating distributions can be seen from Tropical Rainfall Measuring Mission (TRMM studies of the linear response to asymmetric heating of a balanced vortex showed that the resulting

  10. Global Ensemble Predic1ons of 2009's Tropical Cyclones

    E-print Network

    Hamill, Tom

    and Joint Typhoon Warning Center 5 #12;Ensemble systems evaluated · Run ourselves on NSF U TexasFng). 7 #12;Rules for including a parFcular storm in "homogeneous" comparisons of models A vs. B · Storm must be tracked and at least tropical depression strength at iniFal Fme of forecast · Ensemble

  11. Characterizing multi-hazard extreme distributions of coastal flooding induced by tropical cyclones

    NASA Astrophysics Data System (ADS)

    Díez-Sierra, Javier; Toimil, Alexandra; del Jesus, Manuel; Méndez, Fernando; Medina, Raúl

    2015-04-01

    Coastal areas, which are among the most populated regions on Earth, are the interface between continental land and the ocean. As a consequence of their location, they are subject to complex flooding dynamics, arising from the interaction between coastal and continental dynamics. This complexity is translated to the characterization of extreme distributions and the effects induced by climate change in the distribution of extreme events. In this work, we develop a methodology that serves to characterize the extreme distribution of flooding in a coastal environment. We focus in the dynamics induced by tropical cyclones that are both marine (storm surge and wave run-up) and continental (precipitation and runoff). Our approach makes uses of historical cyclones that have affected the study area in the past. This ensemble is augmented by synthetically generated cyclones in order to better cover the range of possible tracks. A maximum dissimilarity algorithm is used on the augmented database to select a reduced subset of tracks best representing the variability on the data (Camus et al. 2014). This subset is used to carry out a dynamical downscaling. Numerical simulations are carried out for these subset of tropical cyclones to derive the spatial fields of wind (by means of the Hydromet-Rankine Vortex model) and rainfall (using R-Clipper model) induced by the cyclone. SWAN model is used to derive the wave fields (Díaz et al. 2014), H2D to derive the storm surge fields and a CUENCAS-like model (IH-Mole) to derive runoff fields. All the flood-inducing dynamics are the input to the RFSM-EDA model that computes flood depths for the study area. A Monte Carlo simulation is used to generate synthetic time series of tropical cyclones. Tropical cyclone climate is related to the spatial patterns of sea surface temperature (SST) fields using a non-linear clustering technique, which are used in turn as the main driver of a Monte Carlo simulation. Flood time series are derived from cyclone time series using the dynamical downscaling database and interpolation, for those cyclones that have not been simulated. Our hybrid approach (mixing statistical and dynamical downscaling) allows us to compute any statistic of the complete flooding distribution at every location of the study site. Moreover, making use of SST data from simulations of future climate, obtained from general circulation models (AOGCM), we can study the effects of climate change in these distributions of extremes. Diaz-Hernandez, G., Mendez, F. J., & Mínguez, R. (2014). Numerical analysis and diagnosis of the hydrodynamic effects produced by hurricane Gordon on the coast of Spain. Weather and Forecasting, (2014). Camus, P., Menéndez, M., Méndez, F. J., Izaguirre, C., Espejo, A., Cánovas, V., Pérez, J., Rueda, A., Losada, I.J. & Medina, R. (2014). A weather-type statistical downscaling framework for ocean wave climate. Journal of Geophysical Research: Oceans, 119(11), 7389-7405.

  12. Identifying recharge from tropical cyclonic storms, Baja California Sur, Mexico.

    PubMed

    Eastoe, Christopher J; Hess, Greg; Mahieux, Susana

    2015-04-01

    Groundwater in the Todos Santos watershed in southern Baja California, and throughout the peninsula south of latitude 28°N, has values of (?18 O‰, ?D‰) ranging between (-8.3, -57) and (-10.9, -78). Such negative values are uncharacteristic of the site latitude near the sea level. Altitude effects do not explain the isotope data. Tropical depressions originating along the Pacific coast of North America yield rain with isotopic depletion; rain from these weather systems in southern Arizona commonly has ?18O values<-10‰ in comparison with amount-weighted mean summer and fall rain at -6‰. Isotope data indicate hurricane rain as the predominant source of recharge in southern Baja California, where named tropical depressions bring large rains (>50?mm) at least once every 2 to 3 years, and along the Pacific coast between Jalisco and Oaxaca. PMID:24635484

  13. Study of tropical cyclone "Fanoos" using MM5 model - a case study

    NASA Astrophysics Data System (ADS)

    Ramalingeswara Rao, S.; Muni Krishna, K.; Bhanu Kumar, O. S. R. U.

    2009-01-01

    Tropical cyclones are one of the most intense weather hazards over east coast of India and create a lot of devastation through gale winds and torrential floods while they cross the coast. So an attempt is made in this study to simulate track and intensity of tropical cyclone "Fanoos", which is formed over the Bay of Bengal during 5-10 December 2005 by using mesoscale model MM5. The simulated results are compared with the observed results of India Meteorological Department (IMD); results show that the cumulus parameterization scheme, Kain-Fritsch (KF) is more accurately simulated both in track and intensity than the other Betts-Miller (BM) and Grell Schemes. The reason for better performance of KF-1 scheme may be due to inclusion of updrafts and downdrafts. The model could predict the minimum Central Sea Level Pressure (CSLP) as 983 hPa as compared to the IMD reports of 984 hPa and the wind speed is simulated at maximum 63 m/s compared to the IMD estimates of 65 m/s. Secondly "Fanoos" development from the lagrangian stand point in terms of vertical distribution of Potential Vorticity (PV) is also carried out around cyclone centre.

  14. Understanding the impact of model resolution on tropical cyclones in CAM5 using rotating radiative-convective equilibrium

    NASA Astrophysics Data System (ADS)

    Reed, Kevin; Chavas, Daniel

    2015-04-01

    In our continued effort to understand the climate system and improve its representation in general circulation models (GCMs) it is crucial to develop new methods to evaluate these models. This is certainly true as the GCM community advances towards high horizontal resolutions (i.e., grid spacing less than 0.5 degrees), which will require interpreting and improving the performance of many model components. Of specific interest is the simulation of tropical cyclones at these spatial scales. Idealized, or reduced complexity, frameworks can be used to investigate how model assumptions impact behavior across scales. Here we explore the implication of horizontal resolution on tropical cyclones in GCMs using an idealized global rotating radiative-convective equilibrium (RCE) configuration. The National Center for Atmospheric Research and U.S. Department of Energy supported Community Atmosphere Model 5 (CAM5) is configured for an ocean-covered earth with diurnally varying, spatially uniform insolation and spatially uniform rotation, a setup that permits the formation of tropical cyclones throughout the entire global domain. CAM5 is run with the spectral element dynamics package at two horizontal resolutions: a standard resolution of approximately 1 degree grid spacing and a high-resolution of approximately 0.25 degree grid spacing. In this unique testbed, the statistics of tropical cyclone intensity and outer size, as measured by the azimuthal-mean radius of 12 m/s, are analyzed under both configurations. Implications of the results for both model development and tropical cyclone physics are discussed.

  15. Current Enhanced Atlantic Tropical Cyclone Frequency: A Climate-Change Impact?

    NASA Astrophysics Data System (ADS)

    Holland, G. J.; Bruyere, C.

    2010-12-01

    Previous studies of Atlantic tropical cyclone response to anthropogenic climate change have assumed that this has occurred as a quasi-linear trend from around the turn of the 20th century. However, comparison of Global Climate Model (GCM) simulations with and without forcing by anthropogenic gases indicates that the warming due to climate change component was indistinguishable from natural variability until the mid 20th century (Meehl et al 2004). The global change trend became distinct from the annual variability by ~1975. This analysis suggests that internal variability may not be a dominant contributor to the current record temperatures in the MDR, in disagreement with early studies that concluded it was entirely due to internal variability associated with the Atlantic Multidecadal Oscillation (AMO) or similar. Other studies have shown that the warming in the MDR could be explained by changes in both radiative forcing from anthropogenic considerations or by a combination of both radiative and internal effects. Here we adopt the working hypothesis that anthropogenic forcing of climate change moved above the natural climate variability noise level after 1960 and that the majority of the current record level of MDR SST is due to anthropogenic forcing (see Gillett et al for a summary). While this will undoubtedly be controversial, we provide evidence that it fits the available evidence far better than the century-long linear increase that has been assumed in previous studies. We are considering the impacts of this hypothesis on all aspects of Atlantic tropical cyclones; however this presentation will focus on frequency. We first discuss the potential impacts of data errors and shown that these are negligible over the period of interest. We next utilize the association between tropical cyclone frequency and the MDR SST, the MDR SST anomaly compared to the tropics as a whole, and a Genesis Parameter (GP) that incorporates a range of environmental parameters. We find that the current enhanced tropical cyclone frequency arises mainly from climate change with a minority contribution from internal variability. Gillett, N. P., P. A. Stott, and B. D. Santer (2008), Attribution of cyclogenesis region sea surface temperature change to anthropogenic influence, Geophys. Res. Lett., 35, L09707, doi:10.1029/2008GL033670. Meehl, Gerald A., Warren M. Washington, Caspar M. Ammann, Julie M. Arblaster, T. M. L. Wigley, Claudia Tebaldi, 2004: Combinations of Natural and Anthropogenic Forcings in Twentieth-Century Climate. J. Climate, 17, 3721-3727.

  16. Mesoscale Aspects of the Downshear Reformation of a Tropical Cyclone

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance fights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 m/s and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of: rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intense.

  17. Sediment transport off Bangladesh: the power of tropical cyclones recorded in a submarine canyon

    NASA Astrophysics Data System (ADS)

    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.

  18. Cyclone-induced net sediment transport pathway on the continental shelf of tropical Australia inferred from reef talus deposits

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.; Heap, Andrew D.

    2009-09-01

    Tropical cyclones affect storm-dominated sediment transport processes that characterise Holocene shelf deposits in many shelf environments. A summary of cyclone-associated deposits in the Great Barrier Reef published by Larcombe and Carter [2004. Cyclone pumping, sediment partitioning and the development of the Great Barrier Reef shelf system: a review. Quaternary Science Reviews 23, pp. 107-135 indicates a pervasive northwards orientation of deposits on the lee side of reefs and other obstacles. In this paper, we describe the geomorphology of reef talus deposits found in the Gulf of Carpentaria and Arafura Sea, Australia, that we attribute to tropical cyclones. The orientation of these deposits is also indicative of a consistent, along-coast transport pathway. The deposits are located on the leeward side of submerged coral reefs; they are up to 10 m in thickness, comprised of re-worked carbonate sand and gravel and radiocarbon dating indicates that they are of Holocene age. An explanation for the consistent along-coast cyclone transport pathway is presented based on previously published hydrodynamic modelling results. These models illustrate how currents generated by the passage of a cyclone are asymmetric in plan view, such that stronger flows are generated between the eye of the cyclone and the coast. The result of the passage of many cyclones over geologic timescales is a net along-coast sediment transport pathway located on the inner- to mid-shelf, possibly extending over the entire length of northern Australia's coastline. This process provides an explanation for the observed sediment transport patterns on modern tropical continental shelves, as well as a basis for the interpretation of ancient tropical shelf deposits.

  19. Extra-tropical cyclonic\\/anticyclonic activity in North-Eastern Pacific and air temperature extremes in Western North America

    Microsoft Academic Search

    Alice Favre; Alexander Gershunov

    2006-01-01

    Synoptic extra-tropical cyclone and anticyclone trajectories have been constructed from mean daily sea level pressure (SLP)\\u000a data using a new automated scheme. Frequency, intensity and trajectory characteristics of these transients have been summarized\\u000a to form indices describing wintertime cyclonic and anticyclonic activity over the North-Eastern Pacific (east of 170°W) during\\u000a 1950–2001. During this period, the strength of anticyclones gradually diminished

  20. Recently increased tropical cyclone activity and inferences concerning coastal erosion and inland hydrological regimes in New Zealand and Eastern Australia

    Microsoft Academic Search

    Patrick J. Grant

    1981-01-01

    For the area bounded by 0–35 °S latitude and 105 °E–105 °W longitude a significant increase of tropical cyclone frequency occurred about 1954–55 and this regime persisted throughout the 1960s and 1970s. Probably this frequency increase was accompanied by an increase of cyclonic storm intensity. It was related to an atmospheric pressure regime change over Australasia which commenced in early

  1. On predicting future economic losses from tropical cyclones: Comparing damage functions for the Eastern USA

    NASA Astrophysics Data System (ADS)

    Geiger, Tobias; Levermann, Anders; Frieler, Katja

    2015-04-01

    Recent years have seen an intense scientific debate of what to expect from future tropical cyclone activity under climate change [1,2]. Besides the projection of cyclones' genesis points and trajectories it is the cyclone's impact on future societies that needs to be quantified. In our present work, where we focus on the Eastern USA, we start out with a comprehensive comparison of a variety of presently available and novel functional relationships that are used to link cyclones' physical properties with their damage caused on the ground. These so-called damage functions make use of high quality data sets consisting of gridded population data, exposed capital at risk, and information on the cyclone's extension and its translational and locally resolved maximum wind speed. Based on a cross-validation ansatz we train a multitude of damage functions on a large variety of data sets in order to evaluate their performance on an equally sized test sample. Although different damage analyses have been conducted in the literature [3,4,5,6], the efforts have so far primarily been focused on determining fit parameters for individual data sets. As our analysis consists of a wide range of damage functions implemented on identical data sets, we can rigorously evaluate which (type of) damage function (for which set of parameters) does best in reproducing damages and should therefore be used for future loss analysis with highest certainty. We find that the benefits of using locally resolved data input tend to be outweighed by the large uncertainties that accompany the data. More coarse and generalized data input therefore captures the diversity of cyclonic features better. Furthermore, our analysis shows that a non-linear relation between wind speed and damage outperforms the linear as well as the exponential relationship discussed in the literature. In a second step, the damage function with the highest predictive quality is implemented to predict potential future cyclone losses for the Eastern USA until the year 2100. The projection is based on downscaling five different GCM model runs for the RCP8.5 scenario, as conducted by Emanuel et al. [7], and accounts for population and GDP changes relying on the newly developed Shared Socioenonomic Pathways (SSPs) [8]. We hereby contribute valuable input to the scientific community as well as the societies at risk. The possibility of extending this work to different regions in order to access the future impact of tropical cyclones on a global scale will also be discussed. References [1] Thomas R. Knutson, John L. McBride, Johnny Chan, Kerry Emanuel, Greg Holland, Chris Landsea, Isaac Held, James P. Kossin, A. K. Srivastava, and Masato Sugi. Tropical cyclones and climate change. Nature Geoscience, 3(3):157-163, 2010. [2] Robert Mendelsohn, Kerry Emanuel, Shun Chonabayashi, and Laura Bakkensen. The impact of climate change on global tropical cyclone damage. Nature Climate Change, 2(3):205-209, 2012. [3] Silvio Schmidt, Claudia Kemfert, and Peter Höppe. The impact of socio-economics and climate change on tropical cyclone losses in the USA. Regional Environmental Change, 10(1):13-26, 2009. [4] William D. Nordhaus. The Economics of Hurricanes and Implications of Global Warming. Climate Change Economics, 01(01):1-20, 2010. [5] Kerry Emanuel. Global Warming Effects on U.S. Hurricane Damage. Weather, Climate, and Society, 3(4):261-268, 2011. [6] Richard J. Murnane and James B. Elsner. Maximum wind speeds and US hurricane losses. Geophysical Research Letters, 39(16):707, 2012. [7] Kerry Emanuel. Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century. Proceedings of the National Academy of Sciences of the United States of America, 110(30):12219-24, 2013. [8] Detlef P. van Vuuren, Keywan Riahi, and Richard Moss. A proposal for a new scenario framework to support research and assessment in different climate research communities. Global Environmental Change, 22(1):21-35, 2012.

  2. Typhoon Vamei: An Equatorial Tropical Cyclone Formation C.-P. Chang, Ching-Hwang Liu1 , Hung-Chi Kuo2

    E-print Network

    Chang, Chih-Pei

    1 Typhoon Vamei: An Equatorial Tropical Cyclone Formation C.-P. Chang, Ching-Hwang Liu1 , Hung-free. Typhoon Vamei, which developed near Singapore on 27 December 2001, was the first recorded tropical cyclone latitude for a typhoon was 3.3°N for Typhoon Sarah in 1956 (Fortner, 1958). Typhoon Vamei formed near

  3. Tropical Cyclones and Ice Cores: Developing a Long Term Perspective

    NASA Astrophysics Data System (ADS)

    Urmann, D.

    2006-12-01

    Accurate forecasts of seasonal typhoon activity in the northwestern Pacific are of critical importance to the people living in the densely populated coastal cities of east Asia. The El Niño Southern Oscillation (ENSO) is a key component of these forecasts as past observations indicate that El Niño (La Niña) events are associated with an increase (decrease) in the proportion of typhoons striking Japan, Korea and Taiwan (The Philippines and the South China Sea). The ice core-derived ?18O record from the Quelccaya ice cap (Peru) is strongly correlated (r=0.646, p<0.001, 1856-2003) with sea surface temperatures (SST) in NINO 4, a region of the western equatorial Pacific that is a sensitive recorder of ENSO. Additionally, a direct relationship is observed between ?18O and both the mean longitude of typhoon development (r=0.59, p<.001, 1945-2003) and the number of typhoon days (r=0.59, p<.001, 1945-2003). The typhoon and ice core ?18O records exhibit patterns of decadal-scale variability that closely resemble the longer-term variations in NINO 4 SSTs (decadal NINO 4 SST variability is known as the "Decadal ENSO"). Annual values of ?18O are significantly different (p=.05) between La Niña and El Niño years suggesting that ?18O reflects not only the Decadal ENSO but also the superimposed interannual ENSO variability. ENSO-driven shifts in the SSTs and large-scale atmospheric circulation patterns may provide a physical linkage to explain the observed relationships among ?18O, SSTs and typhoon activity. The effect of the ongoing warming on ENSO is unclear, but any changes in the background frequency or intensity of ENSO events would likely affect the development of typhoons and cyclones in the Pacific as well as hurricanes in the Atlantic. The 1500-year ?18O record from Quelccaya offers a unique opportunity to examine how ENSO-driven hurricane and typhoon activity responded to large-scale climate forcing (changes) in the past and may provide a more complete perspective and better understanding that will be required to evaluate the likely effects under future climate change scenarios

  4. Skill of probabilistic decadal forecasts regarding the frequencies of Northern Hemisphere extra-tropical cyclones

    NASA Astrophysics Data System (ADS)

    Tim, Kruschke; Rust, Henning; Kadow, Christopher; Ulbrich, Uwe; Leckebusch, Gregor

    2015-04-01

    Mid-latitude cyclones exert a large influence on primary meteorological parameters such as surface temperature, wind speed or precipitation. The variability in their frequency of occurrence is thus important for climate variability in the extra-tropics and consequently a crucial parameter for skillful predictions on interannual to multi-decadal time scales. This work investigates the skill of a prediction system which is being developed to make climate forecasts for time scales of up to 10 years. Within MiKlip - the German initiative for decadal prediction - five different hindcast sets for the period 1961-2010 were set up, all produced by the same model system (MPI-ESM-LR), but following different strategies for initialization (anomaly-initialization and full-field-initialization from different reanalysis data sets as well as initialization from an assimilation experiment). Based on 41 annual initializations for each of the strategies, it is analyzed whether these forecast systems can provide skillful (compared to climatological forecasts and uninitialized climate projections) probabilistic three-category forecasts enhanced, normal or decreased) of Northern Hemisphere extra-tropical winter (ONDJFM) cyclone frequencies with different lead times. It is shown, that they exhibit significant skill for the North Atlantic and Pacific storm track,mainly for lead times of 2-5 years. Prediction skill for the subset of intense (strongest 25% according to laplacian of sea-level pressure) cyclones is generally higher than for the full set of all detected systems. A comparison of the different initialization strategies indicates systematic differences for some lead times and regions. First exploratory analyses regarding potential sources of found predictive skill indicate local oceanic forcing of lower troposphere baroclinicity but also remote influences - especially of tropical origin - modulating large scale circulation patterns.

  5. Tropical Cyclone Zoe devastates South Pacific Islands on Sunday December 29, 2002.

    NSDL National Science Digital Library

    Lori Perkins

    2003-01-09

    Tropical Cyclone Zoe brought winds in excess of 300 km per hour (186 mph) and dangerous waves to the south pacific islands on December 29, 2002. The visualization zooms down to the storm and then shows the overall rain structure. Blue represents areas where at least 0.5 inches of rain fell per hour. Green shows at least 1.0 inch of rain. Yellow is 1.7 inches and red depicts more than 2.2 inches of rain per hour.

  6. The Challenges of Interpreting Microwave-Sounded Height- Registered Water near Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Fishbein, E.; Fetzer, E.; Kahn, B.; Lambrightsen, B.; Teixeira, J.

    2008-12-01

    Satellite-derived coincident profiles of water, and liquid water (cloud properties) provide some of the best constraints on the energetics of tropical cyclones. The problem addressed is how accuracy depends on amount and distribution of cloud liquid water. We focus on products derived from the AMSU/MHS sounders using algorithms from the AIRS/AMSU/HSB investigations. We use error analysis and inter omparisons with total precipitable and liquid water from AMSR-E and MODIS. Accuracy degrades as cloud liquid water amount increases and the vertical distribution of water vapor depends on climatological constraints on either partitioning between phases or vertical correlation.

  7. Communicating the Threat of a Tropical Cyclone to the Eastern Range

    NASA Technical Reports Server (NTRS)

    Winters, Katherine A.; Roeder, William P.; McAleenan, Mike; Belson, Brian L.; Shafer, Jaclyn A.

    2012-01-01

    The 45th Weather Squadron (45 WS) has developed a tool to help visualize the Wind Speed Probability product from the National Hurricane Center (NHC) and to help communicate that information to space launch customers and decision makers at the 45th Space Wing (45 SW) and Kennedy Space Center (KSC) located in east central Florida. This paper reviews previous work and presents the new visualization tool, including initial feedback as well as the pros and cons. The NHC began issuing their Wind Speed Probability product for tropical cyclones publicly in 2006. The 45 WS uses this product to provide a threat assessment to 45 SW and KSC leadership for risk evaluations with an approaching tropical cyclone. Although the wind speed probabilities convey the uncertainty of a tropical cyclone well, communicating this information to customers is a challenge. The 45 WS continually strives to provide the wind speed probability information to customers in a context which clearly communicates the threat of a tropical cyclone. First, an intern from the Florida Institute of Technology (FIT) Atmospheric Sciences department, sponsored by Scitor Corporation, independently evaluated the NHC wind speed probability product. This work was later extended into a M.S. thesis at FIT, partially funded by Scitor Corporation and KSC. A second thesis at FIT further extended the evaluation partially funded by KSC. Using this analysis, the 45 WS categorized the probabilities into five probability interpretation categories: Very Low, Low, Moderate, High, and Very High. These probability interpretation categories convert the forecast probability and forecast interval into easily understood categories that are consistent across all ranges of probabilities and forecast intervals. As a follow-on project, KSC funded a summer intern to evaluate the human factors of the probability interpretation categories, which ultimately refined some of the thresholds. The 45 WS created a visualization tool to express the timing and risk for multiple locations in a single graphic. Preliminary results on an on-going project by FIT will be included in this paper. This project is developing a new method of assigning the probability interpretation categories and updating the evaluation of the performance of the NHC wind speed probability analysis.

  8. Pattern Classification of Tropical Cyclone Tracks over the Western North Pacific using a Fuzzy Clustering Method

    NASA Astrophysics Data System (ADS)

    Kim, H.; Ho, C.; Kim, J.

    2008-12-01

    This study presents the pattern classification of tropical cyclone (TC) tracks over the western North Pacific (WNP) basin during the typhoon season (June through October) for 1965-2006 (total 42 years) using a fuzzy clustering method. After the fuzzy c-mean clustering algorithm to the TC trajectory interpolated into 20 segments of equivalent length, we divided the whole tracks into 7 patterns. The optimal number of the fuzzy cluster is determined by several validity measures. The classified TC track patterns represent quite different features in the recurving latitudes, genesis locations, and geographical pathways: TCs mainly forming in east-northern part of the WNP and striking Korean and Japan (C1); mainly forming in west-southern part of the WNP, traveling long pathway, and partly striking Japan (C2); mainly striking Taiwan and East China (C3); traveling near the east coast of Japan (C4); traveling the distant ocean east of Japan (C5); moving toward South China and Vietnam straightly (C6); and forming in the South China Sea (C7). Atmospheric environments related to each cluster show physically consistent with each TC track patterns. The straight track pattern is closely linked to a developed anticyclonic circulation to the north of the TC. It implies that this ridge acts as a steering flow forcing TCs to move to the northwest with a more west-oriented track. By contrast, recurving patterns occur commonly under the influence of the strong anomalous westerlies over the TC pathway but there definitely exist characteristic anomalous circulations over the mid- latitudes by pattern. Some clusters are closely related to the well-known large-scale phenomena. The C1 and C2 are highly related to the ENSO phase: The TCs in the C1 (C2) is more active during La Niña (El Niño). The TC activity in the C3 is associated with the WNP summer monsoon. The TCs in the C4 is more (less) vigorous during the easterly (westerly) phase of the stratospheric quasi-biennial oscillation. This study may be applied to the statistical-dynamic long-range forecast model of TC activity as well as the diagnostic study of TC activity.

  9. Evaluation of official tropical cyclone landfall forecast issued by India Meteorological Department

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Nayak, D. P.; Sharma, Monica; Sharma, R. P.; Bandyopadhyay, B. K.

    2015-06-01

    India Meteorological Department (IMD) introduced the objective tropical cyclone (TC) track forecast valid for next 24 hrs over the North Indian Ocean (NIO) in 2003. It further extended the validity period up to 72 hrs in 2009. Here an attempt is made to evaluate the TC landfall forecast issued by IMD during 2003-2013 (11 years) by calculating the landfall point forecast error (LPE) and landfall time forecast error (LTE). The average LPE is about 67, 95, and 124 km and LTE is about 4, 7, and 2 hrs, respectively for 24, 48, and 72-hr forecasts over the NIO as a whole during 2009-2013. The accuracy of TC landfall forecast has been analysed with respect to basin of formation (Bay of Bengal, Arabian Sea, and NIO as a whole), specific regions of landfall, season of formation (pre-monsoon and post-monsoon seasons), intensity of TCs (cyclonic storm (CS), and severe cyclonic storm (SCS) or higher intensities) at the time of initiation of forecast and type of track of TCs (climatological/straight moving and recurving/looping type). The LPE is less over the BOB than over the AS for all forecast lengths up to 72 hrs. Similarly, the LPE is less during the post-monsoon season than during pre-monsoon season. The LPEs are less for climatologically moving/straight moving TCs than for the recurving/looping TCs.

  10. Summary of the NHC/TPC Tropical Cyclone Track and Intensity Guidance Models

    NSDL National Science Digital Library

    This reference describes the models used for forecasting hurricanes by the the National Hurricane Center (NHC) in Miami, Florida, which issues 72-hour tropical cyclone track and intensity forecasts four times per day for all storms in the north Atlantic and eastern north Pacific east of 140 degrees west. The track forecasts are the storm latitude and longitude (to the nearest tenth of a degree) and the intensity forecasts are the 1-minute maximum sustained surface wind. There is information about the entities that maintain the models, which are the Tropical Prediction Center (TPC), National Center for Environmental Predictions (NCEP), and the Environmental Modeling Center (EMC). Nine track guidance models are explained along with four intensity guidance models. The site offers an explanation of model verification and tables that display average errors for the track and intensity models.

  11. The Relationship of Tropical Cyclone Convective Intensity to Passive Microwave Observations

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Guillory, Anthony; LaFontaine, Frank J.; Cecil, Dan; Heymsfield, Gerald; Arnold, James E. (Technical Monitor)

    2002-01-01

    During the 1998 and 2001 hurricane seasons, the Advanced Microwave Precipitation Radiometer (AMPR) was flown aboard the National Aeronautics and Space Administration (NASA) ER-2 high altitude aircraft as part of the Third Convection And Moisture EXperiment (CAMEX-3) and the Fourth Convection And Moisture Experiment (CAMEX-4). Several hurricanes and tropical storms were sampled during these experiments. The passive microwave observations of these tropical cyclones collected at frequencies of 10.7, 19.35, 37.1, and 85.5 GHz will be presented to explain differences in precipitation features of the hurricanes. In particular, the relationship of the passive microwave signatures of precipitation-sized ice to vertical updraft strength will be examined as a possible indicator of future convective intensity. Correlated aircraft radar, lightning, visible and infrared information will also be examined to provide further insight.

  12. Atlantic Tropical Cyclone Monitoring with AMSU-A: Estimation of Maximum Sustained Wind Speeds

    NASA Technical Reports Server (NTRS)

    Spencer, Roy W.; Braswell, William D.

    2001-01-01

    The first Advanced Microwave Sounding Unit temperature sounder (AMSU-A) was launched on the NOAA-15 satellite on 13 May 1998. The AMSU-A's higher spatial and radiometric resolutions provide more useful information on the strength of the middle- and upper-tropospheric warm cores associated with tropical cyclones than have previous microwave temperature sounders. The gradient wind relationship suggests that the temperature gradient near the core of tropical cyclones increases nonlinearly with wind speed. The gradient wind equation is recast to include AMSU-A-derived variables, Stepwise regression is used to determine which of these variables is most closely related to maximum sustained winds (V(sub max)). The satellite variables investigated include the radially averaged gradients at two spatial resolutions of AMSU-A channels 1-10 T(sub b) data (delta(sub r)T(sub B)), the squares of these gradients, a channel-15-based scattering index (SI(sub 89)), and area-averaged T(sub B). Calculations of T(sub B) and delta(sub r)T(sub B) from mesoscale model simulations of Andrew reveal the effects of the AMSU spatial sampling on the cyclone warm core presentation. Stepwise regression of 66 AMSU-A terms against National Hurricane Center V(sub max) estimates from the 1998 and 1999 Atlantic hurricane season confirms the existence of a nonlinear relationship between wind speed and radially averaged temperature gradients near the cyclone warm core. Of six regression terms, four are dominated by temperature information, and two are interpreted as correcting for hydrometeor contamination. Jackknifed regressions were performed to estimate the algorithm performance on independent data. For the 82 cases that had in situ measurements of V(sub max), the average error standard deviation was 4.7 m/s. For 108 cases without in situ wind data, the average error standard deviation was 7.5 m/s Operational considerations, including the detection of weak cyclones and false alarm reduction, are also discussed.

  13. Atlantic Tropical Cyclone Monitoring with AMSU-A: Estimation of Maximum Sustained Wind Speeds

    NASA Technical Reports Server (NTRS)

    Spencer, Roy; Braswell, William D.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    The first Advanced Microwave Sounding Unit temperature sounder (AMSU-A) was launched on the NOAA-15 satellite on 13 May 1998. The AMSU-A's higher spatial and radiometric resolutions provide more useful information on the strength of the middle and upper tropospheric warm cores associated with tropical cyclones than have previous microwave temperature sounders. The gradient wind relationship suggests that the temperature gradient near the core of tropical cyclones increases nonlinearly with wind speed. We recast the gradient wind equation to include AMSU-A derived variables. Stepwise regression is used to determine which of these variables is most closely related to maximum sustained winds (V(sub max)). The satellite variables investigated include the radially averaged gradients at two spatial resolutions of AMSU-A channels 1 through 10 T(sub b) data (delta(sub r)T(sub b)), the squares of these gradients, a channel 15 based scattering index (SI-89), and area averaged T(sub b). Calculations of Tb and delta(sub r)T(sub b) from mesoscale model simulations of Andrew reveal the effects of the AMSU spatial sampling on the cyclone warm core presentation. Stepwise regression of 66 AMSU-A terms against National Hurricane Center (NHC) V(sub max) estimates from the 1998 and 1999 Atlantic hurricane season confirms the existence of a nonlinear relationship between wind speed and radially averaged temperature gradients near the cyclone warm core. Of six regression terms, four are dominated by temperature information, and two are interpreted as correcting for hydrometeor contamination. Jackknifed regressions were performed to estimate the algorithm performance on independent data. For the 82 cases that had in situ measurements of V(sub max), the average error standard deviation was 4.7 m/s. For 108 cases without in situ wind data, the average error standard deviation was 7.5 m/s. Operational considerations, including the detection of weak cyclones and false alarm reduction are also discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. ESTIMATING THE BENEFIT OF TRMM TROPICAL CYCLONE DATA IN SAVING LIVES

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.

    2005-01-01

    The Tropical Rainfall Measuring Mission (TRMM) is a joint NASA/JAXA research mission launched in late 1997 to improve our knowledge of tropical rainfall processes and climatology (Kummerow et ai., 2000; Adler et ai., 2003). In addition to being a highly successful research mission, its data are available in real time and operational weather agencies in the U.S. and internationally are using TRMM data and images to monitor and forecast hazardous weather (tropical cyclones, floods, etc.). For example, in 2004 TRMM data were used 669 times for determining tropical cyclone location fixes (National Research Council, 2004). TRMM flies at a relatively low altitude, 400 km, and requires orbit adjustment maneuvers to maintain altitude against the small drag of the atmosphere. There is enough fuel used for these maneuvers remaining on TRMM for the satellite to continue flying until 2011-12. However, most of the remaining fuel may be used to perform a controlled re-entry of the satellite into the Pacific Ocean. The fuel threshold for this operation will be reached in the summer of 2005, although the maneuver would actually occur in late 2006 or 2007. The full science mission would end in 2005 under the controlled re-entry option. This re-entry option is related to the estimated probability of injury (1/5,000) that might occur during an uncontrolled re-entry of the satellite. If the estimated probability of injury exceeds 1/10,000 a satellite is a candidate for a possible controlled re-entry. In the TRMM case the NASA Safety Office examined the related issues and concluded that, although TRMM exceeded the formal threshold, the use of TRMM data in the monitoring and forecasting of hazardous weather gave a public safety benefit that compensated for TRMM slightly exceeding the orbital debris threshold (Martin, 2002). This conclusion was based in part on results of an independent panel during a workshop on benefits of TRMM data in concluded that the benefit of TRMM data in saving lives through its use in operational forecasting could not be quantified. The objective of this paper is to describe a possible technique to estimate the number of lives saved per year and apply it to the TRMM case and the use of its data in monitoring and forecasting tropical cyclones.

  16. Global Tropical Moisture Exports and their Influence on Extratropical Cyclone Activity

    NASA Astrophysics Data System (ADS)

    Knippertz, P.; Wernli, H.; Gläser, G.

    2012-04-01

    Many case studies have shown that heavy precipitation events and rapid cyclogenesis in the extratropics can be fuelled by moist and warm tropical air masses. Often the tropical moisture export (TME) occurs through a longitudinally confined region in the subtropics. Here a climatology of TMEs to both hemispheres is constructed on the basis of seven-day forward trajectories, which were started daily from the tropical lower troposphere and which were required to reach a water vapour flux of at least 100 g kg-1 m s-1 somewhere poleward of 35 degrees. For this analysis 6-hourly European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim re-analysis data have been used for the 32-year period 1979-2010. A comparison with a TME climatology based upon the older ERA-40 re-analysis shows little sensitivity. The results are then related to the deepening of objectively identified (extratropical) cyclones in both hemispheres. On average TME trajectories move upwards and eastwards on their way across the subtropics in both hemispheres and are associated with both moisture and meridional-wind anomalies. TME shows four main regions of activity in both hemispheres: In the northern hemisphere these are the eastern Pacific ("Pineapple Express" region) with a marked activity maximum in boreal winter, the West Pacific with maximum activity in summer and autumn associated with the Asian monsoon, the narrow Great Plains region with a maximum in spring and summer associated with the North American monsoon and the western Atlantic or Gulf Stream region with a rather flat seasonal cycle. In the southern hemisphere activity peaks over the central and eastern Pacific, eastern South America and the adjacent Atlantic, the western Indian Ocean, and western Australia. Southern hemisphere TME activity peaks in boreal winter, particularly over the Atlantic and Pacific Oceans, which suggests a significant influence of northern hemispheric Rossby wave energy propagation across the equator. The interannual variability in several regions is significantly modulated by El Niño. A detailed analysis of TME encounters along individual extratropical cyclone tracks reveals several extraordinary cyclone-deepening events associated with TME trajectories (e.g. storm "Klaus" in January 2009). A statistical analysis quantifies the fraction of explosively deepening cyclones that occur with and without a TME influence.

  17. Sensitivity of Tropical Cyclone Spinup Time to the Initial Entropy Deficit

    NASA Astrophysics Data System (ADS)

    Tang, B.; Corbosiero, K. L.; Rios-Berrios, R.; Alland, J.; Berman, J.

    2014-12-01

    The development timescale of a tropical cyclone from genesis to the start of rapid intensification in an axisymmetric model is hypothesized to be a function of the initial entropy deficit. We run a set of idealized simulations in which the initial entropy deficit between the boundary layer and free troposphere varies from 0 to 100 J kg-1 K-1. The development timescale is measured by changes in the integrated kinetic energy of the low-level vortex. This timescale is inversely related to the mean mass flux during the tropical cyclone gestation period. The mean mass flux, in turn, is a function of the statistics of convective updrafts and downdrafts. Contour frequency by altitude diagrams show that entrainment of dry air into updrafts is predominately responsible for differences in the mass flux between the experiments, while downdrafts play a secondary role. Analyses of the potential and kinetic energy budgets indicate less efficient conversion of available potential energy to kinetic energy in the experiments with higher entropy deficits. Entrainment leads to the loss of buoyancy and the destruction of available potential energy. In the presence of strong downdrafts, there can even be a reversal of the conversion term. Weaker and more radially confined radial inflow results in less convergence of angular momentum in the experiments with higher entropy deficits. The result is a slower vortex spinup and a reduction in steady-state vortex size, despite similar steady-state maximum intensities among the experiments.

  18. The benefits of using short interval satellite images to derive winds for tropical cyclones

    NASA Technical Reports Server (NTRS)

    Rodgers, E.; Gentry, R. C.; Shenk, W. E.; Oliver, V.

    1978-01-01

    During the 1975, 1976, and 1977, NOAA's National Environmental Satellite Service and NASA's Goddard Space Flight Center conducted a cooperative program to determine the optimum resolution and frequency of satellite images for deriving winds to study and forecast tropical cyclones. Rapid scan images were obtained at 7.5 minute interval from SMS-2 for hurricane Eloise and cyclone Caroline, and at 3 minute intervals from GOES-1 for tropical storms Belle, Holly, and Anita. Cloud motions were derived from these images using the Atmospheric and Oceanographic Information Processing System. Winds that were derived from the movement of upper and lower tropospheric level clouds using rapid scan data were compared with the 15 and 30 minute interval data. Greater than 10 (5) times as many clouds could be tracked to obtain winds using 3 and 7.5 minute rapid scan images as when using 15 or 30 minute interval images. A few bright areas within the central dense overcast which appeared to be moving with the winds at low levels were tracked.

  19. Trends in Tropical Cyclone Precipitation and Discharge in Watersheds near Houston, Texas

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Quiring, S. M.; Guneralp, I.; Peacock, W. G.

    2013-12-01

    Daily precipitation and river discharge data for a 60 year period were examined for eight watersheds in the San Jacinto River basin near Houston, Texas to identify significant linear trends and abrupt changes in the precipitation and discharge time series for each watershed. Results show that the tropical cyclone precipitation (TCP) is responsible for 50%-65% of annual maximum discharge events in the watersheds studied. Both change points and linear trends were detected in the 90th percentile precipitation. Increasing trends were also observed in the annual extreme discharge and the 90th percentile discharge. The more developed watersheds tend to have higher mean discharge and greater trends in extreme discharge. Increases in discharge coincided with increases in developed land and decreases in forest. Moreover, developed watersheds tend to have more frequent TCP-related discharge exceeding the 90th percentile after 1980. Therefore, the significant changes in land cover/use in watersheds near Houston are a major cause of the increased flooding risk in recent years. Increases in the discharge variance were also observed indicating that discharge is becoming more variable over time. Key words: Tropical Cyclone, Discharge, Houston

  20. An Estimate of the North Atlantic Basin Tropical Cyclone Activity for the 2010 Hurricane Season

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2010-01-01

    Estimates are presented for the tropical cyclone activity expected for the 2010 North Atlantic basin hurricane season. It is anticipated that the 2010 season will be more active than the 2009 season, reflecting increased frequencies more akin to that of the current more active phase that has been in vogue since 1995. Averages (+/- 1 sd) during the current more active phase are 14.5+/-4.7, 7.8+/-3.2, 3.7+/-1.8, and 2+/- 2, respectively, for the number of tropical cyclones (NTC), the number of hurricanes (NH), the number of major hurricanes (NMH), and the number of United States (U.S.) land-falling hurricanes (NUSLFH). Based on the "usual" behavior of the 10-yma parametric first differences, one expects NTC = 19+/-2, NH = 14+/-2, NMH = 7+/-2, and NUSLFH = 4+/-2 for the 2010 hurricane season; however, based on the "best guess" 10-yma values of surface-air temperature at the Armagh Observatory (Northern Ireland) and the Oceanic Nino Index, one expects NTC > or equals 16, NH > or equals 14, NMH > or equals 7, and NUSLFH > or equals 6.

  1. The Air-Sea Interface and Surface Stress under Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Soloviev, Alexander; Lukas, Roger; Donelan, Mark; Ginis, Isaac

    2013-04-01

    Air-sea interaction dramatically changes from moderate to very high wind speed conditions (Donelan et al. 2004). Unresolved physics of the air-sea interface are one of the weakest components in tropical cyclone prediction models. Rapid disruption of the air-water interface under very high wind speed conditions was reported in laboratory experiments (Koga 1981) and numerical simulations (Soloviev et al. 2012), which resembled the Kelvin-Helmholtz instability at an interface with very large density difference. Kelly (1965) demonstrated that the KH instability at the air-sea interface can develop through parametric amplification of waves. Farrell and Ioannou (2008) showed that gustiness results in the parametric KH instability of the air-sea interface, while the gusts are due to interacting waves and turbulence. The stochastic forcing enters multiplicatively in this theory and produces an exponential wave growth, augmenting the growth from the Miles (1959) theory as the turbulence level increases. Here we complement this concept by adding the effect of the two-phase environment near the mean interface, which introduces additional viscosity in the system (turning it into a rheological system). The two-phase environment includes air-bubbles and re-entering spray (spume), which eliminates a portion of the wind-wave wavenumber spectrum that is responsible for a substantial part of the air sea drag coefficient. The previously developed KH-type interfacial parameterization (Soloviev and Lukas 2010) is unified with two versions of the wave growth model. The unified parameterization in both cases exhibits the increase of the drag coefficient with wind speed until approximately 30 m/s. Above this wind speed threshold, the drag coefficient either nearly levels off or even slightly drops (for the wave growth model that accounts for the shear) and then starts again increasing above approximately 65 m/s wind speed. Remarkably, the unified parameterization reveals a local minimum of the drag coefficient wind speed dependence around 65 m/s. This minimum may contribute to the rapid intensification of storms to major tropical cyclones. The subsequent slow increase of the drag coefficient with wind above 65 m/s serves as an obstacle for further intensification of tropical cyclones. Such dependence may explain the observed bi-modal distribution of tropical cyclone intensity. Implementation of the new parameterization into operational models is expected to improve predictions of tropical cyclone intensity and the associated wave field. References: Donelan, M. A., B. K. Haus, N. Reul, W. Plant, M. Stiassnie, H. Graber, O. Brown, and E. Saltzman, 2004: On the limiting aerodynamic roughness of the ocean in very strong winds, Farrell, B.F, and P.J. Ioannou, 2008: The stochastic parametric mechanism for growth of wind-driven surface water waves. Journal of Physical Oceanography 38, 862-879. Kelly, R.E., 1965: The stability of an unsteady Kelvin-Helmholtz flow. J. Fluid Mech. 22, 547-560. Koga, M., 1981: Direct production of droplets from breaking wind-waves-Its observation by a multi-colored overlapping exposure technique, Tellus 33, 552-563. Miles, J.W., 1959: On the generation of surface waves by shear flows, part 3. J. Fluid. Mech. 6, 583-598. Soloviev, A.V. and R. Lukas, 2010: Effects of bubbles and sea spray on air-sea exchanges in hurricane conditions. Boundary-Layer Meteorology 136, 365-376. Soloviev, A., A. Fujimura, and S. Matt, 2012: Air-sea interface in hurricane conditions. J. Geophys. Res. 117, C00J34.

  2. Possible relationship between East Indian Ocean SST and tropical cyclone affecting Korea

    NASA Astrophysics Data System (ADS)

    Kim, J. Y.; Choi, K. S.; Kim, B. J.

    2014-12-01

    In this study, a strong negative correlation was found between East Indian Ocean (EIO) SST and frequency of summertime tropical cyclone (TC) affecting Korea.For the Warm EIO SST years, the TCs mostly occurred in the southwestern region of tropical and subtropical western Pacific, and migrated west toward the southern coast of China and Indochinese peninsula through the South China Sea. This is because the anomalous easterlies, induced by the development of anomalous anticyclone (weakening of monsoon trough) from the tropical central Pacific to the southern coast of China, served as the steering flows for the westward migration of TCs. In contrast, for the cold EIO SST years, the TCs mostly occurred in the northeastern region of tropical and subtropical western Pacific, and migrated toward Korea and Japan located in the mid-latitudes of East Asia through the East China Sea. This is because the northeastward retreat of subtropical western North Pacific high (SWNPH) was more distinct for the cold EIO SST years compared to the warm EIO SST years. Therefore, the TCs of warm EIO SST years weakened or dissipated shortly due to the effect of geographical features as they land on the southern coast of China and Indochinese peninsula, whereas the TCs of cold EIO SST years had stronger intensity than the TCs of warm EIO SST years as sufficient energy is supplied from the ocean while moving toward Korea and Japan.

  3. A Study of Oceans and Atmospheric Interactions Associated with Tropical Cyclone Activity using Earth Observing Technology

    NASA Astrophysics Data System (ADS)

    Abdullah, Warith; Reddy, Remata

    From October 22nd to 30th, 2012 Hurricane Sandy was a huge storm of many abnormalities causing an estimated 50 billion dollars in damage. Tropical storm development states systems’ energy as product of warm sea surface temperatures (SST’s) and tropical cyclone heat potential (TCHP). Advances in Earth Observing (EO) technology, remote sensing and proxy remote sensing have allowed for accurate measurements of SST and TCHP information. In this study, we investigated rapid intensification of Sandy through EO applications for precipitable water vapor (PWAT), SST’s and TCHP during the period of October 27th. These data were obtained from NASA and NOAA satellites and NOAA National Buoy data center (NDBC). The Sensible Heat (Qs) fluxes were computed to determine available energy resulting from ocean-atmosphere interface. Buoy 41010, 120 NM east of Cape Canaveral at 0850 UTC measured 22.3 °C atmospheric temperatures and 27 °C SST, an interface of 4.7 °C. Sensible heat equation computed fluxes of 43.7 W/m2 at 982.0 mb central pressure. Sandy formed as late-season storm and near-surface air temperatures averaged > 21 °C according to NOAA/ESRL NCEP/NCAR reanalysis at 1000 mb and GOES 13 (EAST) geostationary water vapor imagery shows approaching cold front during October 27th. Sandy encountered massive dry air intrusion to S, SE and E quadrants of storm while travelling up U.S east coast but experienced no weakening. Cool, dry air intrusion was considered for PWAT investigation from closest sounding station during Oct. 27th 0900 - 2100 UTC at Charleston, SC station 72208. Measured PWAT totaled 42.97 mm, indicating large energy potential supply to the storm. The Gulf Stream was observed using NASA Short-term Prediction Research and Transition Center (SPoRT) MODIS SST analysis. The results show 5 °C warmer above average than surrounding cooler water, with > 25 °C water extent approximately 400 NM east of Chesapeake Bay and eddies > 26 °C. Results from sensible heat computations for atmospheric interface suggests unusual warmth associated with Gulf Stream current, such that it provided Sandy with enough kinetic energy to intensify at high latitude. The study further suggests that energy gained from Caribbean TCHP and Gulf Stream SST’s were largely retained by Sandy upon losing tropical-cyclone characteristics and merging with strong cold front and polar jet stream. Storms of Sandy’s magnitude and unusual source of energy resulting from Gulf Stream may indicate a building average for tropical cyclone development and intensity for North Atlantic, particularly as the GOM waters continue to warm on seasonal averages.

  4. Tropical Cyclone Outflow Structure Observed during the Hurricane and Severe Storms Sentinel (HS3) and Tropical Cyclone Intensity (TCI) Experiments (2012-2014)

    NASA Astrophysics Data System (ADS)

    Black, P. G.; Hendricks, E. A.; Doyle, J. D.; Moskaitis, J.; Velden, C.

    2014-12-01

    Little is known about the detailed vertical and horizontal structure of the Tropical Cyclone (TC) outflow layer owing to lack of in-situ observations in this region over the years. We hypothesize that TC outflow structure change due either to external environmental interactions or internal dynamical changes are related to TC intensity changes, making the outflow layer an important region of study for improvement of TC predictability. Dropsonde profiles through TC outflow layers were obtained during the Hurricane and Severe Storms Sentinel (HS3) experiment (2012-2014) and the Tropical Cyclone Intensity (TCI) experiment (2014). Using mini-dropsondes deployed with the Airborne Vertical Atmospheric Profiling System (AVAPS) from a NASA Global Hawk and eXpendable Digital Dropsondes (XDDs) deployed with the High Definition Sounding System (HDSS) from a NASA WB-57F, new insights into the vertical structure of the TC outflow layer have been obtained. Atmospheric Motion Vectors (AMVs) show that 'far-field' outflow jet dropsondes in Hurricane Leslie (2012) were obtained during a period of jet development and deformation in response the 'pincer effect' of an upper trough to the east and an upper cold low to west of Leslie. We speculate that the resulting deformation of the outflow layer and associated jet feature may have been responsible for limiting further development of Leslie. AMVs in Hurricane Nadine (2012) and pre-TC Gabrielle (2013) showed that outflow jets sampled by dropsondes developed over time scales of several hours. Wind profile observations in outflow jet 'roots' near 'convective bursts' showed that they were weaker and thicker near the convection and became thinner and stronger downstream as the 'far-field' region was sampled. All dropsonde profiles showed that the outflow layer contained numerous thin isothermal layers and layers of enhanced vertical wind shear. These numerous thin unstable layers were characterized by a super-critical Richardson number in excess of ¼. The outflow layer therefore appears to contain multiple transient thin unstable layers generating turbulence that may play a role in the dynamics of the outflow layer and its impact on TC predictability.

  5. Influence of upper-ocean stratification on tropical cyclone-induced surface cooling in the Bay of Bengal

    E-print Network

    Influence of upper-ocean stratification on tropical cyclone-induced surface cooling in the Bay, and barrier layer in this region, with fresher waters, deeper upper-ocean stratification, and thicker barrier in oceanic stratification rather than to differences in TC wind energy input. During the postmonsoon season

  6. Response of Tropical Cyclone Potential Intensity to a Global Warming Scenario in the IPCC AR4 CGCMs

    E-print Network

    Wang, Yuqing

    Response of Tropical Cyclone Potential Intensity to a Global Warming Scenario in the IPCC AR4 CGCMs (TC) potential intensity (PI) and its control parameters in transient global warming simulations the first 70 years of a transient run forced by 1% per year CO2 increase. The linear trend over the period

  7. Climate response to tropical cyclone-induced ocean mixing in an Earth system model of intermediate complexity

    Microsoft Academic Search

    Ryan L. Sriver; Marlos Goes; Michael E. Mann; Klaus Keller

    2010-01-01

    We introduce a parameterization of ocean mixing by tropical cyclones (TCs) into an Earth system model of intermediate complexity. The parameterization is based on previously published global budgets of TC-induced mixing derived from high-resolution satellite measurements of anomalous sea surface temperatures along storm tracks. Recognizing the caveats introduced, for example, by the simplified model structure, we find that the representation

  8. Shore & Beach Vol. 73, No. 2 & 3, Spring/Summer 2005, pp.20 The 2004 Atlantic basin tropical cyclone season

    E-print Network

    Gray, William

    tropical cyclone season was one of the most active and destructive on re- cord. A total of fourteen named or major hurricanes (sustained winds >= 111 mph) developed during the season. These six major hurricanes lasted for 22.25 days, which is the most major hurricane days since the 1926 season. The primary reason

  9. The landfall and structure of a tropical cyclone: The sensitivity of model predictions to soil moisture parameterizations

    Microsoft Academic Search

    Ashu Dastoor; T. N. Krishnamurti

    1991-01-01

    A regional mesoscale multi-level primitive equation model is used to predict the landfall and structure of a tropical cyclone. Three areas of model sensitivity are addressed in this paper; (1) the horizontal resolution, which includes the representation of orography; (2) the impact of an improved representation of the distribution of land surface soil moisture on the landfall problem; and (3)

  10. Real-Time Track Prediction of Tropical Cyclones over the North Indian Ocean Using the ARW Model

    E-print Network

    Real-Time Track Prediction of Tropical Cyclones over the North Indian Ocean Using the ARW Model The performance of the Advanced Research version of the Weather Research and Forecasting (ARW) model in real-time and warning systems. The Advanced Research version of the Weather Re- search and Forecasting system (ARW

  11. A Comparison of Extra-tropical Cyclones in Recent Re-analyses; ERA-INTERIM, NASA-MERRA,

    E-print Network

    Hodges, Kevin

    A Comparison of Extra-tropical Cyclones in Recent Re-analyses; ERA-INTERIM, NASA-MERRA, NCEP to spatial resolution except NASA-MERRA which has larger in- tensities for several different measures-Interim is lower than in the NH, but for NASA-MERRA and NCEP-CFSR the number matched is similar to the NH. The mean

  12. Tropical cyclone identification and tracking system using integrated neural oscillatory elastic graph matching and hybrid RBF network track mining techniques

    Microsoft Academic Search

    Raymond S. T. Lee; James N. K. Liu

    2000-01-01

    We present an automatic and integrated neural network-based tropical cyclone (TC) identification and track mining system. The proposed system consists of two main modules: 1) TC pattern identification system using neural oscillatory elastic graph matching model; and 2) TC track mining system using hybrid radial basis function network with time difference and structural learning algorithm. For system evaluation, 120 TC

  13. The combined effects of beta-shear and environmental shear on a dry tropical cyclone in a numerical model

    E-print Network

    Nolan, David S.

    The combined effects of beta-shear and environmental shear on a dry tropical cyclone in a numerical to the advection of the upper-level structure of the TC downstream, less optimal eye warming forced by asymmetric such that vortex reaches new balanced state, with only gradual weakening over course of several days. Dry

  14. "Electrically-Hot" Convection and Tropical Cyclone Development in the Eastern Atlantic

    NASA Astrophysics Data System (ADS)

    Leppert, K.; Petersen, W. A.; Williams, E.

    2008-12-01

    The depth and intensity of convective-scale "hot" towers in intensifying tropical disturbances has been hypothesized to play a role in tropical cyclogenesis via dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this investigation we investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") resident in African Easterly Waves (AEW) may play in tropical cyclogenesis over the eastern Atlantic Ocean. NCEP reanalysis data for the months of July to November for the years 2004, 2006, and 2007 are analyzed for the domain of 5° N - 15° N and 50° W - 30° E. Specifically, NCEP data for individual AEWs are partitioned into northerly, southerly, trough, and ridge phases using the 700 hPa meridional winds. Subsequently, information from National Hurricane Center storm reports were divided up into developing and non-developing waves (i.e. tropical cyclogenesis). Finally, composites were created of developing and non- developing waves using the NCEP variables, but with the inclusion of lightning flash count and infrared brightness temperature information. The Zeus and World Wide Lightning Location Network lightning data were used for the lightning information, and the IR brightness temperature data was extracted from the NASA global-merged infrared brightness temperature dataset. Results indicate that developing AEW composites have greater low-level positive vorticity (9.0E-06 s-1 vs. 4.5E-06 s-1), slightly greater upward vertical motion (-0.035 Pascals s-1 vs. -0.028 Pascals s-1), slightly higher upper-level divergence(2.5E-06 s-1 vs. 1.8E-06 s-1), a higher mid-level (i.e. 600 hPa) moisture anomaly (0.6 g kg-1 vs. -0.15 g kg-1), cooler average brightness temperatures (273.5K vs. 278.4K), and more lightning strikes (1018 vs. 641 strikes) when compared against the non-developing composites. These results collectively indicate that AEWs producing tropical cyclones may have increased convective activity- and in particular, convective activity producing more lightning. To complement the composite work, we are further investigating the degree to which the aforementioned behavior is observed in individual cases. Work is also proceeding to identify whether the higher lightning strike/cooler brightness temperature behavior in the AEW tropical cyclone-developing composites is the result of more widespread convection producing a larger frequency of lightning, or just a few more vertically developed and electrically-intense convective towers.

  15. Changes in large-scale controls of Atlantic tropical cyclone activity with the phases of the Atlantic multidecadal oscillation

    NASA Astrophysics Data System (ADS)

    Caron, Louis-Philippe; Boudreault, Mathieu; Bruyère, Cindy L.

    2015-04-01

    Atlantic tropical cyclone activity is known to oscillate between multi-annual periods of high and low activity. These changes have been linked to the Atlantic multidecadal oscillation (AMO), a mode of variability in Atlantic sea surface temperature which modifies the large-scale conditions of the tropical Atlantic. Cyclone activity is also modulated at higher frequencies by a series of other climate factors, with some of these influences appearing to be more consistent than others. Using the HURDAT2 database and a second set of tropical cyclone data corrected for possible missing storms in the earlier part of the record, we investigate, through Poisson regressions, the relationship between a series of climate variables and a series of metrics of seasonal Atlantic cyclone activity during both phases of the AMO. We find that, while some influences, such as El Niño Southern oscillation, remain present regardless of the AMO phase, other climate factors show an influence during only one of the two phases. During the negative phase, Sahel precipitation and the North Atlantic oscillation (NAO) are measured to play a role, while during the positive phase, the 11-year solar cycle and dust concentration over the Atlantic appear to be more important. Furthermore, we show that during the negative phase of the AMO, the NAO influences all our measures of tropical cyclone activity, and we go on to provide evidence that this is not simply due to changes in steering current, the mechanism by which the NAO is usually understood to impact Atlantic cyclone activity. Finally, we conclude by demonstrating that our results are robust to the sample size as well as to the choice of the statistical model.

  16. Integrating and Visualizing Tropical Cyclone Data Using the Real Time Mission Monitor

    NASA Technical Reports Server (NTRS)

    Goodman, H. Michael; Blakeslee, Richard; Conover, Helen; Hall, John; He, Yubin; Regner, Kathryn

    2009-01-01

    The Real Time Mission Monitor (RTMM) is a visualization and information system that fuses multiple Earth science data sources, to enable real time decision-making for airborne and ground validation experiments. Developed at the NASA Marshall Space Flight Center, RTMM is a situational awareness, decision-support system that integrates satellite imagery, radar, surface and airborne instrument data sets, model output parameters, lightning location observations, aircraft navigation data, soundings, and other applicable Earth science data sets. The integration and delivery of this information is made possible using data acquisition systems, network communication links, network server resources, and visualizations through the Google Earth virtual globe application. RTMM is extremely valuable for optimizing individual Earth science airborne field experiments. Flight planners, scientists, and managers appreciate the contributions that RTMM makes to their flight projects. A broad spectrum of interdisciplinary scientists used RTMM during field campaigns including the hurricane-focused 2006 NASA African Monsoon Multidisciplinary Analyses (NAMMA), 2007 NOAA-NASA Aerosonde Hurricane Noel flight, 2007 Tropical Composition, Cloud, and Climate Coupling (TC4), plus a soil moisture (SMAP-VEX) and two arctic research experiments (ARCTAS) in 2008. Improving and evolving RTMM is a continuous process. RTMM recently integrated the Waypoint Planning Tool, a Java-based application that enables aircraft mission scientists to easily develop a pre-mission flight plan through an interactive point-and-click interface. Individual flight legs are automatically calculated "on the fly". The resultant flight plan is then immediately posted to the Google Earth-based RTMM for interested scientists to view the planned flight track and subsequently compare it to the actual real time flight progress. We are planning additional capabilities to RTMM including collaborations with the Jet Propulsion Laboratory in the joint development of a Tropical Cyclone Integrated Data Exchange and Analysis System (TC IDEAS) which will serve as a web portal for access to tropical cyclone data, visualizations and model output.

  17. Occurrence of Landslides during the Approach of Tropical Cyclone Juliette (2001) to Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Antinao, J.; Farfan, L.

    2012-12-01

    The approach of Tropical Cyclone Juliette to the Baja California Peninsula in September 2001 triggered at least 419 landslides. Most of the landslides were shallow slips and debris slides, of limited areal extent, which were converted rapidly into debris flows to be exported quickly out of the mountain areas towards the lowlands. Main factors affecting landslide occurrence were total storm rainfall and intensity, aspect, geology and vegetation association. Two processes can be distinguished as initiating slope failure. The first process is linked to failures in concave topography, where accumulation of rainfall from exposed bedrock slopes generated excess overland flow that aggregated to generate a 'fire hose' effect on the base of slopes, mobilizing regolith. A second process involved a combination of wind and excess overland flow developed in the more convex or planar upper slopes, where heterogeneous regolith has formed in time following successional changes in vegetation associations along the oak-dry tropical forest ecotone. In this area, wind uprooted trees that dislodged large regolith and bedrock blocks, priming hillslopes for further runoff concentration. From the analysis of historical information, an estimative threshold curve for triggering landslides in this region is sketched. It was also determined that storms like Juliette approach the southern peninsula on average once every 100 years. Denudation estimates are in the higher end of the spectrum for a tectonically passive margin. These estimates should be considered when taking decisions regarding management of water resources in this area through damming of streams. The results emphasize the need for a more detailed representation of the spatial distribution of the rainfall and winds for this mountainous region frequently affected by the passage of tropical cyclones.

  18. Trends and low frequency variability of extra-tropical cyclone activity in the ensemble of twentieth century reanalysis

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolan L.; Feng, Y.; Compo, G. P.; Swail, V. R.; Zwiers, F. W.; Allan, R. J.; Sardeshmukh, P. D.

    2013-06-01

    An objective cyclone tracking algorithm is applied to twentieth century reanalysis (20CR) 6-hourly mean sea level pressure fields for the period 1871-2010 to infer historical trends and variability in extra-tropical cyclone activity. The tracking algorithm is applied both to the ensemble-mean analyses and to each of the 56 ensemble members individually. The ensemble-mean analyses are found to be unsuitable for accurately determining cyclone statistics. However, pooled cyclone statistics obtained by averaging statistics from individual members generally agree well with statistics from the NCEP-NCAR reanalyses for 1951-2010, although 20CR shows somewhat weaker cyclone activity over land and stronger activity over oceans. Both reanalyses show similar cyclone trend patterns in the northern hemisphere (NH) over 1951-2010. Homogenized pooled cyclone statistics are analyzed for trends and variability. Conclusions account for identified inhomogeneities, which occurred before 1949 in the NH and between 1951 and 1985 in the southern hemisphere (SH). Cyclone activity is estimated to have increased slightly over the period 1871-2010 in the NH. More substantial increases are seen in the SH. Notable regional and seasonal variations in trends are evident, as is profound decadal or longer scale variability. For example, the NH increases occur mainly in the mid-latitude Pacific and high-latitude Atlantic regions. For the North Atlantic-European region and southeast Australia, the 20CR cyclone trends are in agreement with trends in geostrophic wind extremes derived from in-situ surface pressure observations. European trends are also consistent with trends in the mean duration of wet spells derived from rain gauge data in Europe.

  19. High-Resolution Modeling to Assess Tropical Cyclone Activity in Future Climate Regimes

    SciTech Connect

    Lackmann, Gary

    2013-06-10

    Applied research is proposed with the following objectives: (i) to determine the most likely level of tropical cyclone intensity and frequency in future climate regimes, (ii) to provide a quantitative measure of uncertainty in these predictions, and (iii) to improve understanding of the linkage between tropical cyclones and the planetary-scale circulation. Current mesoscale weather forecasting models, such as the Weather Research and Forecasting (WRF) model, are capable of simulating the full intensity of tropical cyclones (TC) with realistic structures. However, in order to accurately represent both the primary and secondary circulations in these systems, model simulations must be configured with sufficient resolution to explicitly represent convection (omitting the convective parameterization scheme). Most previous numerical studies of TC activity at seasonal and longer time scales have not utilized such explicit convection (EC) model runs. Here, we propose to employ the moving nest capability of WRF to optimally represent TC activity on a seasonal scale using a downscaling approach. The statistical results of a suite of these high-resolution TC simulations will yield a realistic representation of TC intensity on a seasonal basis, while at the same time allowing analysis of the feedback that TCs exert on the larger-scale climate system. Experiments will be driven with analyzed lateral boundary conditions for several recent Atlantic seasons, spanning a range of activity levels and TC track patterns. Results of the ensemble of WRF simulations will then be compared to analyzed TC data in order to determine the extent to which this modeling setup can reproduce recent levels of TC activity. Next, the boundary conditions (sea-surface temperature, tropopause height, and thermal/moisture profiles) from the recent seasons will be altered in a manner consistent with various future GCM/RCM scenarios, but that preserves the large-scale shear and incipient disturbance activity. This will allow (i) a direct comparison of future TC activity that could be expected for an active or inactive season in an altered climate regime, and (ii) a measure of the level of uncertainty and variability in TC activity resulting from different carbon emission scenarios.

  20. Subgrid Convective Cloud Parameterization for Tropical Cyclone Prediction at Grey-Zone Resolution

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Bao, Jian-Wen; Chen, Baode

    2015-04-01

    The use of only the explicit microphysics scheme in high-resolution weather prediction models at grey-zone horizontal resolutions (i.e., from one to a few kilometers)is often insufficient to neutralize moist convective instability for the entire grid box because the grid-resolved updrafts may not be strong enough. A consequence of such a problem is that unrealistically-intense grid-size convection may occur in model simulations, which in tropical cyclone simulations can lead to erroneous representation of tropical cyclone development. The use of a conventional subgrid convective cloud parameterization scheme along with the explicit microphysics scheme to alleviate this problem is not appropriate since such a scheme assumes that the subgrid updraft area is much smaller than the model grid size and this assumption becomes invalid when the grid size is a few kilometers or smaller. This presentation will introduce a subgrid convective cloud parameterization scheme that has been developed at the Shanghai Typhoon Institute in which the aforementioned assumption about the subgrid updraft area is removed. The newly-developed scheme can be used for grid spacing equal to or smaller than a few kilometers to help eliminate moist convective instability for the entire grid point. The scheme behaves similarly to conventional ones when the subgrid updraft area is much smaller than the grid size. As the subgrid updraft area in a grid box approaches the grid size, the parameterized sub-grid convection in the scheme diminishes. A special consideration is taken in the scheme to ensure that a unified formulation of cloud microphysics is applied to both subgrid and grid-resolved clouds. Preliminary results from experimenting with the scheme in the Advanced Research WRF (ARW) model with an idealized tropical cyclone intensification case will be reported in this presentation. It will be demonstrated that the scheme converges (i.e., the parameterized convection diminishes as the updraft area in a grid box approaches the grid size)as the model's horizontal resolution increases. Remaining issues and challenges in refining this scheme for operational models will also be discussed.

  1. Analysis of CAPE in Intensifying Tropical Cyclones Simulated by CM1

    NASA Astrophysics Data System (ADS)

    Lee, Marguerite; Frisius, Thomas

    2015-04-01

    The transition of a tropical storm to a full blown hurricane (Typhoon) during intensification can be a source of great debate among many well respected scientists. As a result there is a lack of a comprehensive understanding of intensification. The present study aims to lessen some of the confusion by addressing the role of convective available potential energy (CAPE) in cyclogenesis. Previous work by others fail to include this due to assumptions that allow the intensification to occur under different conditions. A series of sensitivity tests were conducted using an idealised set up in the cloud resolving non-hydrostatic model CM1. A base state provided by a Dunion sounding was used with the vortex being initialised using the Rotunno and Emanuel's scheme and the Morrison double-moment cloud microphysical scheme was adopted. All experiments employed a 2km grid spacing with 600 grid points in the horizontal and 500m grid spacing with 59 grid points in the vertical. Two sets of sensitivity tests were done where the distribution of CAPE was investigated. In the first group the base state temperature was perturbed such that the atmosphere cooled and warmed at 0.5K/km and 1K/km in the vertical direction. In the second group the value for the exchange coefficient for enthalpy was increased and decreased by a factor of 2 and 4 for both cases. Since we are only interested in the rate of intensification most results were taken at the time when the rate of intensification was the highest. In the temperature perturbation experiments warming the atmosphere creates less than ideal conditions for cyclogenesis which results in no hurricane developing when the air was warmed by 1K/km and a very weak tropical cyclone developing when the air was warmed by 0.5K/km. As a result of this there is very little CAPE present in both cases. In contrast, cooling the air provides better conditions for cyclogenesis. The amount of CAPE is much greater when the air was cooled by 0.5K/km but the final intensity of the cyclone is not. In fact the intensification of the cyclone under both cooling conditions are very similar. The results for the second experiment group are more distinct. Although the coefficient was halved and quartered, there is still a strong cyclone present but the amount of CAPE is less. The experiment with a reduction by factor of 4 exhibits very little CAPE whereas the one where it was reduced by a factor of 2 has some but still a rather small amount of CAPE. There is a greater amount of CAPE for when the coefficient is increased by a factor of 4. Additionally, the intensification rate is also much greater. The intensification rate appears to be sensitive to the presence of CAPE. These results suggest that CAPE is a vital quantity for tropical cyclone intensification.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. The use of reflected GPS signals to retrieve ocean surface wind speeds in tropical cyclones

    NASA Astrophysics Data System (ADS)

    Katzberg, Stephen J.; Dunion, Jason; Ganoe, George G.

    2013-07-01

    the first intentional acquisition of GPS signals reflected from water bodies, one of the objectives which has driven the research is to determine whether the acquired signal can provide useful geophysical information about the reflecting surface. One obvious condition of considerable interest is ocean surface wind speed. Theory suggested that the reflection technique, a form of bistatic RADAR, would be sensitive to surface roughness which in turn is driven by wind speed. This paper reports the results derived from data acquired over the past decade of applying the GPS reflection technique to ocean surface winds, particularly ocean surface winds in tropical cyclones. Examples of wind speed retrievals will be given for some illustrative cases of hurricanes and tropical storms. The results from several hurricanes and tropical storms on how the signal was calibrated will be presented. In addition, a quantitative comparison will be given between dropsondes deployed by NOAA during the storms and GPS reflection derived wind speeds taken at the same time. Conditions in which the GPS technique offers excellent comparisons as well as examples where the comparison is not so good will be presented. Suggestions will be given as to when the GPS technique can be used with confidence and when it is likely to be at variance with other methods.

  4. Water security and societal impacts of tropical cyclones in northwestern Mexico, 1970-2010

    NASA Astrophysics Data System (ADS)

    Scott, C. A.; Farfan, L.

    2012-12-01

    Hydroclimatic variability is one of several potential threats to water security, defined as sustainable quantities and qualities of water for resilient societies and ecosystems in the face of uncertain global environmental change. Other threats can stem from human dimensions of global change, e.g., long-distance trade of water-intensive agricultural commodities or pollution resulting from industrial production and mining in response to rising global market demand. Drought and water scarcity are considered the principal, chronic, hydroclimatic drivers of water insecurity in arid and semi-arid regions. In these conditions, however, rainfall is both the water-supply lifeline and, in extreme events, the cause of flood hazard. In this study, we consider the monsoon-dominated Pacific coast of Mexico and assess the human impacts from tropical cyclone landfall over the past four decades (1970-2010). Storm data from the U.S. National Hurricane Center, rainfall reports from Mexico's National Meteorological Service, and indicators from an international disaster database at Belgium's Université Catholique de Louvain are used to assess the impacts of more than 30 landfall events. For the ten events with the greatest population impact, between 20,000 to 800,000 people were affected by each landfalling cyclone. Strong winds and heavy rainfall, particularly when sustained over periods of 1-3 days, result in significant property damage and loss of life. Results indicate that, in densely populated areas, excessive rainfall accumulations and high daily rates are important causes of cyclone disasters. Strengthening water security associated with extreme events requires planning via structured exchanges between scientists and decision-makers. Adaptive management that accounts for uncertainties, initiates responses, and iteratively assesses outcomes is the thrust of an emerging water-security initiative for the arid Americas that seeks to strengthen water security in northwestern Mexico.Norbert Impacts in Alamos, Sonora, 12 Oct. 2008

  5. AMSU-A Tropical Cyclone Maximum Sustained Winds and Web Site

    NASA Technical Reports Server (NTRS)

    Spencer, Roy; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    The Advanced Microwave Sounding Unit (AMSU)-A instruments on the NOAA-15 and NOAA-16 satellites provide information on the warm cores of tropical cyclones from oxygen channel brightness temperature (Tb) measurements near 55 GHz. With appropriate assumptions, cyclone-scale Tb gradients can be directly related to middle-to-lower tropospheric height gradients. We have developed a method for diagnosis of maximum sustained winds (Vmax) from radially averaged Tb gradients in several of the AMSU channels. Calibration of the method with recon-based (or other in situ) winds results in better agreement than with Dvorak wind estimates. Gradient wind theory shows that the warm core Tb gradient signal increases non-linearly with wind speed, making microwave temperature sounders useful for diagnosing high wind speeds, but at the expense of a minimum useful detection limit of about 40 knots. It is found that accurate wind diagnoses depend upon (1) accounting for hydrometeor effects in the AMSU channels, and (2) maximizing signal-to-noise, since the 50 km resolution data cannot fully resolve the temperature gradients in the Vmax region, typically 10-20 km in scale. AMSU imagery and max diagnoses from specific hurricanes will be shown, including independent tests from the 2000 hurricane season.

  6. MISR CMVs and Multiangular Views of Tropical Cyclone Inner-Core Dynamics

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Diner, David J.; Garay, Michael J; Jovanovic, Veljko M.; Lee, Jae N.; Moroney, Catherine M.; Mueller, Kevin J.; Nelson, David L.

    2010-01-01

    Multi-camera stereo imaging of cloud features from the MISR (Multiangle Imaging SpectroRadiometer) instrument on NASA's Terra satellite provides accurate and precise measurements of cloud top heights (CTH) and cloud motion vector (CMV) winds. MISR observes each cloudy scene from nine viewing angles (Nadir, +/-26(sup o), +/-46(sup o), +/-60(sup o), +/-70(sup o)) with approximatel 275-m pixel resolution. This paper provides an update on MISR CMV and CTH algorithm improvements, and explores a high-resolution retrieval of tangential winds inside the eyewall of tropical cyclones (TC). The MISR CMV and CTH retrievals from the updated algorithm are significantly improved in terms of spatial coverage and systematic errors. A new product, the 1.1-km cross-track wind, provides high accuracy and precision in measuring convective outflows. Preliminary results obtained from the 1.1-km tangential wind retrieval inside the TC eyewall show that the inner-core rotation is often faster near the eyewall, and this faster rotation appears to be related linearly to cyclone intensity.

  7. Change in surface latent heat flux and its association with tropical cyclone genesis in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Zhou, Lian-Tong; Chen, Guosen; Wu, Renguang

    2015-01-01

    The present study investigates the influence of June through November (JJASON) thermal state of the western North Pacific warm pool on surface latent heat flux and their association with tropical cyclone (TC) genesis by using 25 level water temperature data with European Centre for Medium-Range Weather Forecasts (ECWMF) operational ocean analysis (ORA-S3), the monthly mean fluxes from Objectively Analyzed Air-sea Fluxes (OAFlux) Project, and the tropical cyclone data from the International Best Track Archive for Climate Stewardship (IBTrACS). It is found that positive (negative) latent heat flux anomalies over the western North Pacific are associated with warm (cold) state of the warm pool. The analysis suggests that the change in sea-air humidity difference has a direct contribution to surface latent heat flux anomalies over the western Pacific in warm state years of the warm pool. However, the change in surface wind speed is the main cause of surface latent heat flux anomalies over central tropical Pacific. In cold state years, change in the sea-air humidity difference has a direct contribution to surface latent heat flux anomalies over the western Pacific and central and eastern tropical Pacific, and the change in surface wind speed appears not to be a cause of identified surface latent heat flux anomalies. Moreover, the results show that the sea-air humidity difference contributes to tropical cyclone genesis in warm state years, but in cold state years, tropical cyclone genesis occurs mainly in regions of sea-air humidity difference decrease and surface wind speed increase.

  8. Interannual variability of tropical cyclone activity and regional Hadley circulation over the Northeastern Pacific

    NASA Astrophysics Data System (ADS)

    Zhang, Gan; Wang, Zhuo

    2015-04-01

    The interannual variability of the regional Hadley circulation (HC) and tropical cyclone (TC) activity over the Northeastern Pacific (NEP) was investigated. The interannual variability of the HC in the NEP hurricane season is found dominated by a mode (M1EP) regulating the strength and meridional extent of the Intertropical Convergence Zone. M1EP has a more robust correlation with NEP TC activity than the El Niño-Southern Oscillation sea surface temperature indices. The strong correlation is attributed to the impacts of M1EP on environmental conditions. In addition, the leading mode of the Atlantic HC, which has an anticorrelation with M1EP, also strongly impacts NEP TC activity. The findings, together with Zhang and Wang (2013), highlight the role of the HC in controlling the variability of TC activity as well as the interbasin connection between the NEP and the Atlantic. The regional HC is thus recommended as a useful metric to benchmark models in simulating TC activity.

  9. Vertical structure of tropical cyclones at onset of the rapid intensification in the HWRF model

    NASA Astrophysics Data System (ADS)

    Kieu, Chanh; Tallapragada, Vijay; Hogsett, Wallace

    2014-05-01

    In this study, the tropical cyclone structure at the onset of rapid intensification (RI) is examined using the cloud-permitting version of the Hurricane Weather Research and Forecast (HWRF) model. Idealized experiments with different vortex initial vertical structures in different environments show that the HWRF model vortex possesses a specific constraint in the dynamical and thermodynamic structure at the RI onset including (i) a warm anomaly of 1-3°K, (ii) a moist column with relative humidity > 90% within the storm central region, and (iii) low-level tangential flow ?12 m s-1. Regardless of vortex structures or environment conditions applied in this study, model vortex does not intensify if the above constraint is not established. Such a requirement in the model moisture and dynamical structure at the RI onset can explain why the RI onset is much delayed in dry experiments as compared to the onset in moist experiments.

  10. Change in ocean subsurface environment to suppress tropical cyclone intensification under global warming

    PubMed Central

    Huang, Ping; Lin, I. -I; Chou, Chia; Huang, Rong-Hui

    2015-01-01

    Tropical cyclones (TCs) are hazardous natural disasters. Because TC intensification is significantly controlled by atmosphere and ocean environments, changes in these environments may cause changes in TC intensity. Changes in surface and subsurface ocean conditions can both influence a TC's intensification. Regarding global warming, minimal exploration of the subsurface ocean has been undertaken. Here we investigate future subsurface ocean environment changes projected by 22 state-of-the-art climate models and suggest a suppressive effect of subsurface oceans on the intensification of future TCs. Under global warming, the subsurface vertical temperature profile can be sharpened in important TC regions, which may contribute to a stronger ocean coupling (cooling) effect during the intensification of future TCs. Regarding a TC, future subsurface ocean environments may be more suppressive than the existing subsurface ocean environments. This suppressive effect is not spatially uniform and may be weak in certain local areas. PMID:25982028

  11. Marine climate influences on interannual variability of tropical cyclones in the eastern Caribbean: 1979-2008

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.

    2015-04-01

    Interannual variability of tropical cyclones (TCs) in the eastern Caribbean is studied using MIT-Hurdat fields during the July-October season from 1979 to 2008. TC intensity shows local climate sensitivity particularly for upper ocean currents, salinity and mixed-layer depth, and 200-850 mb wind shear. Remote influences from the Southern Oscillation, Saharan dust, and the South American monsoon are also identified as important. Ocean currents diminish along the coast of South America, so interbasin transfer between the North Brazil and Caribbean Currents declines in seasons of frequent and intense TCs. This is related to a dipole pattern in the sea surface height formed mainly by reduced trade wind upwelling northeast of Venezuela. A low-salinity plume from the Orinoco River spreads across the eastern Caribbean. It is the weaker currents and shallower mixed layer that conspire with surplus heat to build thermodynamic energy available for TC intensification.

  12. Increase in the Intensity of Postmonsoon Bay of Bengal Tropical Cyclones

    SciTech Connect

    Balaguru, Karthik; Taraphdar, Sourav; Leung, Lai-Yung R.; Foltz, Gregory R.

    2014-05-28

    The post-monsoon (October-November) tropical cyclone (TC) season in the Bay of Bengal has spawned many of the deadliest storms in recorded history. Here it is shown that the intensity of post-monsoon Bay of Bengal TCs, and the contribution of major TCs to total TC power, increased during 1981-2010. It is found that changes in environmental parameters are responsible for the observed increases in TC intensity. Increases in sea surface temperature and upper ocean heat content made the ocean more conducive to TC development, while enhanced convective instability made the atmosphere more favorable for the growth of TCs. The largest changes in the atmosphere and ocean occurred in the eastern Bay of Bengal, where nearly all major TCs form. These changes are part of positive linear trends, suggesting that the intensity of post-monsoon Bay of Bengal TCs may continue to increase in the future.

  13. Change in ocean subsurface environment to suppress tropical cyclone intensification under global warming.

    PubMed

    Huang, Ping; Lin, I-I; Chou, Chia; Huang, Rong-Hui

    2015-01-01

    Tropical cyclones (TCs) are hazardous natural disasters. Because TC intensification is significantly controlled by atmosphere and ocean environments, changes in these environments may cause changes in TC intensity. Changes in surface and subsurface ocean conditions can both influence a TC's intensification. Regarding global warming, minimal exploration of the subsurface ocean has been undertaken. Here we investigate future subsurface ocean environment changes projected by 22 state-of-the-art climate models and suggest a suppressive effect of subsurface oceans on the intensification of future TCs. Under global warming, the subsurface vertical temperature profile can be sharpened in important TC regions, which may contribute to a stronger ocean coupling (cooling) effect during the intensification of future TCs. Regarding a TC, future subsurface ocean environments may be more suppressive than the existing subsurface ocean environments. This suppressive effect is not spatially uniform and may be weak in certain local areas. PMID:25982028

  14. Characteristics of Tropical Cyclones in High-resolution Models in the Present Climate

    NASA Technical Reports Server (NTRS)

    Shaevitz, Daniel A.; Camargo, Suzana J.; Sobel, Adam H.; Jonas, Jeffrey A.; Kim, Daehyun; Kumar, Arun; LaRow, Timothy E.; Lim, Young-Kwon; Murakami, Hiroyuki; Reed, Kevin; Roberts, Malcom J.; Scoccimarro, Enrico; Vidale, Pier Luigi; Wang, Hui; Wehner, Michael F.; Zhao, Ming; Henderson, Naomi

    2014-01-01

    The global characteristics of tropical cyclones (TCs) simulated by several climate models are analyzed and compared with observations. The global climate models were forced by the same sea surface temperature (SST) fields in two types of experiments, using climatological SST and interannually varying SST. TC tracks and intensities are derived from each model's output fields by the group who ran that model, using their own preferred tracking scheme; the study considers the combination of model and tracking scheme as a single modeling system, and compares the properties derived from the different systems. Overall, the observed geographic distribution of global TC frequency was reasonably well reproduced. As expected, with the exception of one model, intensities of the simulated TC were lower than in observations, to a degree that varies considerably across models.

  15. Multiannual forecasts of Atlantic U.S. tropical cyclone wind damage potential

    NASA Astrophysics Data System (ADS)

    Caron, Louis-Philippe; Hermanson, Leon; Doblas-Reyes, Francisco J.

    2015-04-01

    There are strong decadal variations in Atlantic hurricane activity, with an active period in the 1950s and 1960s, a quiescent period from the 1970s through the early 1990s and a resurgence in activity since the mid-1990s. Using an index that relies on subpolar gyre temperature and subtropical sea level pressure, two quantities with links to hurricane activity, we show that it is possible to construct reliable 5 year mean forecasts of both basin-wide tropical cyclone activity as well as wind energy associated with hurricanes making landfall along the U.S. coastline. Furthermore, the index is capable of reproducing the major decadal shifts in activity observed over the last 50 years. This is the first time that a forecast system shows significant skill of a landfalling hurricane characteristic at the multiannual time scale and, as such, shows great promise as a valuable climate service product.

  16. Mosaics of canopy openness induced by tropical cyclones in lowland rain forests with contrasting management histories in northeastern Australia

    Microsoft Academic Search

    SIMON J. GROVE; STEPHEN M. TURTON; DANNY T. SIEGENTHALER

    2000-01-01

    ABSTRACT. Tropical Cyclone ‘Rona’ crossed,the coast of the Daintree,lowlands of northeastern,Australia in 1999. This study reports on its impact,on forest canopy openness,at six lowland,rain forest sites with,contrasting,management,histories (old-growth, selectively logged and regrowth). Percentage canopy openness was calculated,from,individual,hemispherical,photographs,taken,from,marked,points below the forest canopy at nine plots per site 3?4 mo before the cyclone, and at the same points a month afterwards. Before

  17. The Structure and Dynamics of Coherent Vortices in the Eyewall Boundary Layer of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Stern, D. P.; Bryan, G. H.

    2014-12-01

    The boundary layer within the eyewall of intense tropical cyclones has been shown to be both highly turbulent and to contain coherent small-scale (of order 1 km) vortices. Dropsonde observations have indicated that extreme updrafts of 10-25 m/s can occur in the lowest 2 km, sometimes as low as a few hundred meters above the surface. These updrafts are often collocated with or found very nearby to local extrema in horizontal wind speed, which sometimes exceed 100 m/s. Here, the CM1 model is used to simulate intense tropical cyclones in an idealized framework, with horizontal grid spacing as fine as ~30 meters. At this grid spacing, the scales of the vortices are well resolved. By examining individual features and compositing over many updrafts, we find that there is a consistent structure and relationship between vorticity, vertical velocity, and near-surface windspeeds. We quantitatively show that buoyancy is not responsible for the acceleration of strong boundary layer updrafts. Instead, the updrafts are forced by dynamical pressure gradients associated with strong gradients in the velocity fields. It is currently unknown whether dropsonde observations represent quasi-vertical profiles through the features, or if instead the sondes are horizontally advected through the features. Using simulated dropsonde trajectories, we show that sondes are likely to be horizontally advected through features, and therefore apparent vertical variability in observed kinematic and thermodynamic profiles may actually be primarily in the horizontal. In observations, extreme updrafts are almost exclusively found in Category 4 and 5 hurricanes. We conduct simulations at varying intensity to investigate whether or not similar features exist in weaker storms. Finally, we have developed an objective algorithm that allows us to track individual updrafts/vortices in time, and we use this to investigate the evolution and lifecycle of these features and to gain further insight into their dynamics.

  18. Investigating sensitivity to Saharan dust in tropical cyclone formation using NASA's adjoint model

    NASA Astrophysics Data System (ADS)

    Holdaway, Daniel

    2015-04-01

    As tropical cyclones develop from easterly waves coming off the coast of Africa they interact with dust from the Sahara desert. There is a long standing debate over whether this dust inhibits or advances the developing storm and how much influence it has. Dust can surround the storm and absorb incoming solar radiation, cooling the air below. As a result an energy source for the system is potentially diminished, inhibiting growth of the storm. Alternatively dust may interact with clouds through micro-physical processes, for example by causing more moisture to condense, potentially increasing the strength. As a result of climate change, concentrations and amount of dust in the atmosphere will likely change. It it is important to properly understand its effect on tropical storm formation. The adjoint of an atmospheric general circulation model provides a very powerful tool for investigating sensitivity to initial conditions. The National Aeronautics and Space Administration (NASA) has recently developed an adjoint version of the Goddard Earth Observing System version 5 (GEOS-5) dynamical core, convection scheme, cloud model and radiation schemes. This is extended so that the interaction between dust and radiation is also accounted for in the adjoint model. This provides a framework for examining the sensitivity to dust in the initial conditions. Specifically the set up allows for an investigation into the extent to which dust affects cyclone strength through absorption of radiation. In this work we investigate the validity of using an adjoint model for examining sensitivity to dust in hurricane formation. We present sensitivity results for a number of systems that developed during the Atlantic hurricane season of 2006. During this period there was a significant outbreak of Saharan dust and it is has been argued that this outbreak was responsible for the relatively calm season. This period was also covered by an extensive observation campaign. It is shown that the adjoint can provide insight into the sensitivity and reveals a relatively low sensitivity to dust compared to, for example, the thermodynamic variables. However a secondary sensitivity though moisture is seen. If dust dries the air it can significantly reduce the cyclone intensity through the moisture.

  19. Tropical Cyclones, Hurricanes, and Climate: NASA's Global Cloud-Scale Simulations and New Observations that Characterize the Lifecycle of Hurricanes

    NASA Technical Reports Server (NTRS)

    Putman, William M.

    2010-01-01

    One of the primary interests of Global Change research is the impact of climate changes and climate variability on extreme weather events, such as intense tropical storms and hurricanes. Atmospheric climate models run at resolutions of global weather models have been used to study the impact of climate variability, as seen in sea surface temperatures, on the frequency and intensity of tropical cyclones. NASA's Goddard Earth Observing System Model, version 5 (GEOS-5) in ensembles run at 50 km resolution has been able to reproduce the interannual variations of tropical cyclone frequency seen in nature. This, and other global models, have found it much more difficult to reproduce the interannual changes in intensity, a result that reflects the inability of the models to simulate the intensities of the most extreme storms. Better representation of the structures of cyclones requires much higher resolution models. Such improved representation is also fundamental to making best use of satellite observations. In collaboration with NOAA's Geophysical Fluid Dynamics Laboratory, GEOS-5 now has the capability of running at much higher resolution to better represent cloud-scale resolutions. Global simulations at cloud-permitting resolutions (10- to 3.5-km) allows for the development of realistic tropical cyclones from tropical storm 119 km/hr winds) to category 5 (>249km1hr winds) intensities. GEOS-5 has produced realistic rain-band and eye-wall structures in tropical cyclones that can be directly analyzed against satellite observations. For the first time a global climate model is capable of representing realistic intensity and track variability on a seasonal scale across basins. GEOS-5 is also used in assimilation mode to test the impact of NASA's observations on tropical cyclone forecasts. One such test, for tropical cyclone Nargis in the Indian Ocean in May 2008, showed that observations from Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU-A) on Aqua substantially reduced forecast track errors. 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. SA is also bringing several state of the art instruments in recent field campaigns to peer under the clouds and study the inner workings of the tropical storms. With the Genesis and Rapid Intensification Processes (GRIP) experiment, a NASA Earth science field experiment in 2010 that includes the Global Hawk Unmanned Airborne System (UAS) configured with a suite of in situ and remote sensing instruments that are observing and characterizing the lifecycle of hurricanes, we expect significant improvement in our understanding of the track and intensification processes with the assimilation of the satellite and field campaign observations of meteorological parameters in the numerical prediction models.

  20. Convection in tropical cyclones associated with vapor volume reduction - a new concept

    NASA Astrophysics Data System (ADS)

    Mardhekar, D.

    2010-09-01

    Low pressure zone formation due to convection in a tropical cyclone is associated by a newly discovered phenomenon. The explanation is based on Avogadro's law. According to the law 18 grams (molecular weight expressed in grams) of water when evaporated occupies 22.414 litres of vapor at standard temperature and pressure (STP). Therefore, 1.0 gram of water in the vapor form will occupy 1.245 litres. That is, 1245 ml volume of vapor at STP when condensed will form 1.0 ml volume of water. Due to the phase change that is from water vapor to liquid water, huge reduction in volume occurs. The process of condensation of vapor into liquid water from the vapor component of the vapor-rich air is continuously taking place in a tropical cyclone particularly in the eye wall on a very large scale. The condensed water precipitates as rain or forms clouds. Each ml of the rain leaves behind a vacant space equal to 1245 ml forming a low-pressure zone and consequently a pressure gradient force is formed. Therefore, when there are continuous heavy rains in the eye wall, the magnitude of the low pressure zone and the pressure gradient force forming continuously in the condensation regions of the eye wall is gigantic. At the same time the latent heat released in the condensation process is absorbed by the remaining air component, it becomes warmer and buoyant, therefore ascends and ultimately escapes from the top of the cyclone as the outflow, again forming a low pressure zone. Thus, continuous condensation and continuous ascent and escape of warm air from the top together form a continuous pressure gradient and the vapour-rich air is continuously sucked up from below, that is from above the sea surface in the region of the eye wall due to the continuously forming pressure gradient force maintaining the near sea surface convergence of the vapour rich air. The value 1245 changes with change in temperature and pressure, but it does not affect the presented concept. The formation of the low pressure zone due to the condensation is instantaneous. The moment the condensation takes place, the low pressure zone and the consequent pressure gradient force is formed at that instant, hence this phenomenon enhances the fuel input process. Thus, the combination of the convection and the low pressure zone formation due to condensation and vapor volume reduction plays a combined role in the dynamics of a tropical cyclone. In case of tornadoes in the tornado alley, tornadoes are formed where warm vapor-rich air from the Gulf of Mexico meets the cold dry air from Canada. Here the same phenomena of vapor volume reduction and consequent formation of the low pressure zone as explained above is dominantly contributing in initiating and maintaining the flow of air forming a tornado. Since this phenomenon is taking place on land and vapour supply is limited, the tornadoes have a short life span.

  1. Decadal changes in tropical cyclone activity over the western North Pacific in the late 1990s

    NASA Astrophysics Data System (ADS)

    He, Haozhe; Yang, Jing; Gong, Daoyi; Mao, Rui; Wang, Yuqing; Gao, Miaoni

    2015-03-01

    A pronounced decadal change in tropical cyclone (TC) activity over the western North Pacific (WNP) in the late 1990s was identified. Based on a comparison of the two epochs that occurred before and after the late 1990s, the TC genesis number exhibited an evident decrease over the southern WNP (S-WNP: 5°-20°N, 105°-170°E) and an increase over the northern WNP (N-WNP: 20°-25°N, 115°-155°E), which partly corresponded to a significant northward migration in the seasonal mean latitudinal location of TC genesis, i.e., from 17.2°N to 18.7°N. After the late 1990s, the northwestward-moving track became the most dominant track mode, accompanied by the weakening of both the westward-moving track and the northeastward-recurving track. Meanwhile, the TC occurrence frequency (TCF) experienced evident increases over southeastern China and the Okinawa islands, while prominent decreases occurred over the South China Sea, the Philippine Sea, Japan and east of Japan. Changes in the TCF were determined by TC genesis changes, TC track shifts and variations in regional TC durations, which were all ascribed to the decadal change in tropical Indo-Pacific sea surface temperature. The full picture on the decadal changes in the WNP TC activity revealed in this study may provide useful guidance for regional TC seasonal forecasts and future projections.

  2. Assessment of Tropical Cyclone Induced Transgression of the Chandeleur Islands for Restoration and Wildlife Management

    NASA Technical Reports Server (NTRS)

    Mitchell, Brandie; Reahard, Ross; Billiot, Amanda; Brown, Tevin; Childs, Lauren

    2009-01-01

    The Chandeleur Islands are the first line of defense against tropical storms and hurricanes for coastal Louisiana. They provide habitats for birds species and are a wildlife refuge; however, distressingly, they are eroding and transgressing at an alarming rate. In 1998, Hurricane Georges caused severe damage to the chain, prompting restoration and monitoring efforts by both Federal and State agencies. Since then, storm events have steadily diminished the condition of the islands. Quantification of shoreline erosion, vegetation, and land loss, from 1979 to 2009, was achieved through the analysis of imagery from Landsat 2-4 Multispectral Scanner, Landsat 4 & 5 Thematic Mapper, and Advanced Spaceborne Thermal Emission and Reflection Radiometer sensors. QuickBird imagery was used to validate the accuracy of these results. In addition, this study presents an application of Moderate Resolution Imaging Spectroradiometer data to assist in tracking the transgression of the Chandeleur Islands. The use of near infrared reflectance calculated from MOD09 surface reflectance data from 2000 to 2009 was analyzed using the Time Series Product Tool. The scope of this project includes not only assessments of the tropical cyclonic events during this time period, but also the effects of tides, winds, and cold fronts on the spatial extent of the islands. Partnering organizations, such as the Pontchartrain Institute for Environmental Research, will utilize those results in an effort to better monitor and address the continual change of the island chain.

  3. Diurnal variations of tropical cyclone precipitation in the inner and outer rainbands

    NASA Astrophysics Data System (ADS)

    Wu, Qiaoyan; Ruan, Zhenxin; Chen, Dake; Lian, Tao

    2015-01-01

    15 years (1998-2012) of satellite-measured precipitation data and tropical cyclone (TC) information, this study estimates the diurnal variations of TC precipitation in its inner core and outer rainbands. It is found that for both weak (tropical storms to category 1 TCs) and strong (categories 2-5 TCs) storms over all six TC basins, the TC precipitation reaches its daily maximum in the morning, but the mean rain rate and diurnal variations are larger in the inner core than in the outer rainbands. With increasing radial distance from the TC center, the diurnal amplitude of precipitation decreases, and the peak time appears progressively later. The outward propagation of diurnal signals from the TC center dominates as an internal structure of the TC convective systems. For all basins examined, the diurnal precipitation maximum within the inner core of a strong storm occurs earlier than the maximum observed in non-TC precipitation; the same result is not found for the outer rainbands. In the North Atlantic, the diurnal variations of TC precipitation in weak storms are much weaker than those in other basins, and the TC precipitation in strong storms shows a semidiurnal cycle in the inner core while exhibiting a clear diurnal cycle with a peak around noon in the outer rainbands.

  4. Monitoring tropical-cyclone intensity using environmental wind fields derived from short-interval satellite images

    NASA Technical Reports Server (NTRS)

    Rodgers, E.; Gentry, R. C.

    1983-01-01

    The feasibility of predicting changes in tropical storm intensity based on satellite observations of the dynamical relationships between the large-scale upper and lower tropospheric circulations surrounding the cyclone and the characteristics of the storm's inner core is studied. Rapid-scan visible images from the SMS-1 and GOES-1 satellites were used to examine the local change in relative angular momentum (RAM), the lower and upper tropospheric environmental areal mean relative vorticity and transverse circulation on three consecutive days for tropical storms Caroline (August, 1975), Anita (August and September, 1977) and Ella (September, 1978). The three case studies suggest that storm intensification may be predicted from the storm's local change of net RAM, with this quantity best correlated with storm intensification after a time lag of 6 hours. Intensification is also found to be related to the environmental lower and upper tropospheric areal-mean relative vorticity, and to the upper tropospheric environmental circulation, which acts either to hinder or to enhance the storm's anticyclonic outflow channels.

  5. Does the Asian monsoon modulate tropical cyclone activity over the South China Sea?

    NASA Astrophysics Data System (ADS)

    Huang, Qian; Guan, Yuping

    2012-11-01

    To investigate whether the Asian monsoon influences tropical cyclone (TC) activity over the South China Sea (SCS), TCs (including tropical storms and typhoons) over the SCS are analyzed using the Joint Typhoon Warning Center dataset from 1945 to 2009. Results show an increasing trend in the frequencies of TC-all (all TCs over the SCS) and TY-all (all typhoons over the SCS), due mainly to an increase in the number of TCs moving into the SCS after development elsewhere. Little change is seen in the number of TCs that form in the SCS. The results of wavelet analysis indicate that the frequency of typhoons (TY) shows a similar oscillation as that of TCs, i.e., a dominant periodicity of 8-16 years around the 1970s for all TC activity, except for TC-mov (TCs that moved into the SCS from the western North Pacific). To examine the relationship between typhoon activity and the summer monsoon, a correlation analysis was performed that considered typhoons, TCs, and five monsoon indexes. The analysis reveals statistically significant negative correlation between the strength of the Southwest Asian summer monsoon and typhoon activity over the SCS, which likely reflects the effect of the monsoon on TC formation in the western North Pacific (WNP) and subsequent movement into the SCS. There is a statistically significant negative correlation between TY-loc (typhoons that developed from TCs formed over the SCS) and the South China Sea summer monsoon and Southeast Asian summer monsoon.

  6. Cloud-to-Ground Lightning Characteristics of a Major Tropical Cyclone Tornado Outbreak

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Goodman, Steven J.

    1999-01-01

    A comprehensive analysis has been conducted of the cloud-to-ground lightning activity occurring within a landfalling tropical cyclone that produced an outbreak of strong and damaging tornadoes. Radar data indicate that 12 convective cells were responsible for 29 tornadoes, several of which received an F3 intensity rating, in the southeastern United States on 16 August 1994 within the remnants of Tropical Storm Beryl. Of these 12 tornadic storms, the most active cell produced 315 flashes over a 5.5 hour period, while the other storms were less active. Three tornadic storms failed to produce any CG lightning at all. In general, the tornadic storms were more active electrically than other non-tornadic cells within Beryl's remnants, although the flash rates were rather modest by comparison with significant midlatitude severe storm events. Very few positive polarity flashes were found in the Beryl outbreak. During some of the stronger tornadoes, CG flash rates in the parent storms showed sharp transient decreases. Doppler radar data suggest the stronger tornadic storms were small supercells, and the lightning data indicate these storms exhibited lightning characteristics similar to those found in heavy-precipitation supercell storms.

  7. North Atlantic tropical cyclone track migration since 1550 A.D. revealed using a Belizean stalagmite

    NASA Astrophysics Data System (ADS)

    Baldini, Lisa; Baldini, James; Frappier, Amy; Ridley, Harriet; Asmerom, Yemane; Prufer, Keith; Breitenbach, Sebastian; Aquino, Valorie; Polyak, Victor; Awe, Jaime

    2015-04-01

    A gradual shift in the geographic distribution of hurricanes and tropical storms from the western Caribbean to the US Atlantic Coast between 1550 and 1983 A.D. is revealed by an annually-resolved, 456-year record of tropical cyclone (TC) activity reconstructed using sub-annually resolved carbon and oxygen isotope ratios in stalagmite YOK-G from Yok Balum Cave, southern Belize. Annual geochemical cycles combined with 230Th dating provide excellent chronological control, and the hurricane season signal intensity is reconstructed using seasonally-specific isotope ratios. The stalagmite hurricane season signal correlates very well with HURDAT2 western Caribbean TC count over the calibration period (1945-1983) as well as over the 25-year verification period. Our record suggests very few TCs affected the western Caribbean in the mid-1500s, but that this was followed by gradually rising western Caribbean TC activity that peaked during the Little Ice Age (LIA). Western Caribbean TC activity then decreases gradually from the mid-1600s to present day, with abrupt shifts at 1790 A.D. and 1870 A.D. Comparison with basin-wide TC reconstructions reveals a northward shift in the geographic distribution of TC impacts over the past few hundred years, from dominantly western Caribbean during the LIA to substantially more along the North American Atlantic margin during the 20th Century. Our reconstruction suggests that NAO variability played a major role in driving these shifts in dominant storm tracks through time.

  8. Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Goodman, Steven; Cammarata, Michael

    2003-01-01

    Data from a single WSR-88D Doppler radar and the National Lightning Detection Network are used to examine in detail the characteristics of the convective storms that produced a severe tornado outbreak within Tropical Storm Beryl's remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 hours, spawning tornadoes over a time period spanning approximately 6.5 hours. Several other tornadic cells also exhibited great longevity, with cell lifetimes greater than ever previously documented in a landfalling tropical cyclone tornado event, and comparable to those found in major midlatitude tornadic supercell outbreaks. Time-height analyses of the three strongest tornadic supercells are presented in order to document storm kinematic structure and to show how these storms appear at different ranges from a WSR-88D radar. In addition, cloud-to-ground (CG) lightning data are examined for the outbreak, the most intense tropical cyclone tornado event studied thus far. Although the tornadic cells were responsible for most of Beryl's CG lightning, flash rates were only weak to moderate, even in the most intense supercells, and in all the tornadic storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced no detectable CG lightning at all. In the stronger cells, there is some evidence that CG lightning rates decreased during tornadogenesis, as has been documented before in some midlatitude tornadic storms. A number of the storms spawned tornadoes just after producing their final CG lightning flashes. Surprisingly, both peak currents and positive flash percentages were larger in Beryl s nontornadic storms than in the tornadic ones. Despite some intriguing patterns, the CG lightning behavior in this outbreak remains mostly inconsistent and ambiguous, and offers only secondary value for warning guidance. The present findings argue in favor of the implementation of observing systems capable of continuous monitoring of total lightning activity in storms.

  9. On tropical cyclone size and intensity changes associated with two types of long-lasting rainbands in monsoonal environments

    NASA Astrophysics Data System (ADS)

    Chen, Buo-Fu; Lee, Cheng-Shang; Elsberry, Russell L.

    2014-04-01

    Tropical cyclones (TCs) in a monsoonal environment may have heavy rain events separate from the eyewall rainfall. Two types of long-lasting rainbands in western North Pacific TCs interacting with the East Asia summer monsoon during 1999-2009 are identified and the effects of these rainbands on TC size and intensity changes are examined. For all of the south-type Outer Mesoscale Convective Systems as defined in our previous study, the TC intensification rate is decreased but the rate of size change is not modified. Long-lasting south-type Enhanced Rainbands (ERBs) that develop between 100 and 300 km radii and move cyclonically are associated with significant TC size increases. Seventy percent of very large typhoons had an ERB during the period when they intensified from tropical storms to typhoons.

  10. Effects of Tropical Cyclones on Ocean Heat Transport as simulated by a High Resolution Coupled General Circulation Model

    Microsoft Academic Search

    E. Scoccimarro; S. Gualdi; A. Bellucci; A. Sanna; M. Vichi; E. Manzini; P. Fogli; A. Navarra; P. Oddo

    2010-01-01

    Tropical cyclones (TCs) activity and their relationship with the Northern hemispheric Ocean Heat Transport (OHT) is investigated. The analysis has been performed using 20C3M (20th Century) and A1B (21st Century) IPCC scenario climate simulations obtained running a state-of-the-art atmosphere-ocean-seaice coupled global model, with high-resolution in the atmosphere. The capability of the model to reproduce a realistic TC climatology has been

  11. Improving Tropical Cyclone Track and Intensity in a Global Model with Local Mesh Refinement

    NASA Astrophysics Data System (ADS)

    Zarzycki, C. M.; Jablonowski, C.

    2014-12-01

    Even with recent improvements in general circulation model (GCM) resolution, tropical cyclones (TCs) are typically underresolved, resulting in fewer or weaker storms than observed. In an effort to alleviate these issues, the use of limited area models (LAMs) allowing for higher resolutions has become popular. However, LAMs require lateral boundary conditions and typically lack two-way communication with the exterior domain. Variable-resolution GCMs can serve as the bridge between traditional global models and high-resolution LAMs. These models can reach 10 km or finer resolution in low-latitude ocean basins where TCs are prevalent. They do so while maintaining global continuity, therefore eliminating the need for externally-forced and possibly numerically and physically inconsistent boundary conditions required by LAMs. Recent developments allow the Community Atmosphere Model's (CAM) Spectral Element (SE) dynamical core to be run on unstructured, statically-nested, variable-resolution grids. We present deterministic CAM-SE model simulations of TCs during recent summers and compare the model's prediction of storm track and intensity to other global and regional models as well as observations. The simulations are run on a 55 km global cubed-sphere grid with additional refinement to 13 km over the Atlantic and Eastern Pacific Oceans. Forecasts are integrated for eight days and the period of analysis spans three months (August, September, and October) during 2012 and 2013. We compare these simulations to identically initialized model runs without mesh refinement to demonstrate the impact of high resolution on TC behavior in CAM. We also investigate cyclone genesis and whether locally high resolution in a global model leads to improved forecast skill at longer lead times. In addition, the impact of the localized refined patch on the remainder of the coarser global solution during the simulation period is discussed.

  12. Factors Affecting the Intensity and Trajectory of Tropical Cyclone Yasi (February 2011)

    NASA Astrophysics Data System (ADS)

    Parker, C.; Lynch, A. H.; Arbetter, T. E.

    2014-12-01

    Tropical Cyclone (TC) Yasi was a rapidly intensifying, category 5 storm that made landfall in Queensland, Australia on February 3rd, 2011. An ensemble of physics sensitivity simulations of TC Yasi using WRF v3.4.1 on a 12-km nested domain demonstrates that the choice of cumulus scheme dominates the outcome of the simulated intensity, trajectory and timing of the cyclone. The choice of microphysics parameterization, planetary boundary layer, surface drag coefficient, and ocean mixed layer scheme had smaller effects. The Modified Tiedtke scheme preferentially activates shallow convection, producing an accurate planetary boundary layer and profile of dry and moist air. However, deep convection and storm intensity are hindered. Thus the scheme produces the most accurate trajectory and landfall location but underestimates intensity and depth of the storm. Conversely, the Kain-Fritsch scheme initiates more deep convection and suppresses shallow convection, allowing storm deepening and intensification. However, subsidence from this convection scheme results in dry air entrainment aloft and a more shallow and moist boundary layer than observed. This scheme more accurately simulates depth and intensity but the trajectory and landfall location are too far south. In all ensemble runs, the simulated event reached maximum intensity over the open ocean and dissipated towards landfall, contrary to Yasi's observed lifecycle. In order to represent potential warming of the East Australian Current (EAC) not resolved in the previous experiments, idealized simulations were performed where a 1°x1° resolution auxiliary sea surface temperature dataset was assimilated into the surface (lower boundary) forcing and 1°K was added to the coastal lagoon. This warming improves the simulated evolution and maintenance of intensity towards landfall and implies that additional warming can fuel further intensification. As the speed, volume transport and temperature of the EAC are predicted to increase with climate change, there are important ramifications for the life cycle of TCs in the area and for coastal settlements in the path of future storms.

  13. Influence of a tropical cyclone on the upper ionosphere according to tomography sounding data over Sakhalin Island in November 2007

    NASA Astrophysics Data System (ADS)

    Vanina-Dart, L. B.; Romanov, A. A.; Sharkov, E. A.

    2011-12-01

    Tomography sounding data for the first half of November 2007 are presented. The sounding was conducted over three points located at the same meridian—Yuzhno-Sakhalinsk (47° N, 143° E), Poronaisk (49° N, 143° E), and Nogliki (51° N, 143° E)—in order to find the possible influence of a tropical cyclone on the upper ionosphere. A change in the foF2 parameter by on average no more than 10-20% is a possible response of the upper ionosphere localized over the tropical cyclone (TC) zone (in the given case, 25°-30° northward and 5°-20° eastward) at a distance of approximately 3800-5500 km from it. A decrease or, vice versa, an increase in foF2 is related to the delay of the measurement moment relative to the beginning of the TC action. The complexity of a morphological analysis of the given event is that a tropical cyclone is a "wideband" (in the longitudinal and, to a lesser degree, in the latitudinal directions) and lasting disturbance source.

  14. Evaluation of Experimental Models for Tropical Cyclone Forecasting in Support of the NOAA Hurricane Forecast Improvement Project (HFIP)

    NASA Astrophysics Data System (ADS)

    Kucera, P. A.; Brown, B.; Williams, C.; Nance, L. B.

    2014-12-01

    The Tropical Cyclone Modeling Team (TCMT) in NCAR's Joint Numerical Testbed (JNT) Program focuses on the verification of experimental forecasts of tropical cyclones (TCs). Activities of the team include the development of new verification methods and tools for TC forecasts and the design and implementation of diagnostic verification experiments to evaluate the performance of tropical cyclone forecast models. For the NOAA Hurricane Forecast Improvement Project (HFIP), the TCMT has designed and conducted verification studies involving various deterministic, ensemble, and statistical regional and global forecast models that participate in the annual HFIP real-time forecast Demonstration experiment. The HFIP Demonstration experiment is conducted during the months of August through October each year. The TCMT has applied new and established statistical approaches to provide statistically meaningful diagnostic evaluations of TC forecasts for storms observed during the Demonstration period. For this study, the TCMT has conducted evaluation of operational and experimental forecast performance for the 2012-2014 hurricane seasons in the North Atlantic and Eastern Pacific Oceans. This presentation will provide an overview of the Demonstration experiment along with a summary of results from the experimental model forecasts for the Atlantic and Eastern Pacific Ocean basins with the goal of documenting potential improvements to hurricane forecasts in comparison to operational baselines.

  15. Large-scale influences on the pre-genesis of tropical cyclone Karl (2010)

    NASA Astrophysics Data System (ADS)

    Griffin, Kyle S.

    The genesis of Tropical Cyclone (TC) Karl (2010) in September 2010 provided a unique opportunity to examine the continuing problem of understanding tropical cyclogenesis. The precursor disturbance to Karl originated from a cluster of showers east of the Windward Islands and was well sampled by ongoing field campaigns, particularly the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT), as the targeted disturbance progressed westward. While traditional genesis theories focusing on moisture and mass fields (e.g. top-down showerhead method) can explain the initial spin-up of the disturbance several days prior to its official genesis, additional perspectives are examined in concert with more traditional methods in order to provide a more complete analysis of the synoptic-scale patterns that influenced the pre-Karl disturbance. A surge of westerly winds from northern South America aids the initial spin-up of the pre-Karl disturbance on 8-9 September, leading to the formation of a nearly closed earth-relative circulation. It can be shown that these anomalous westerly winds are tied to the convectively active phase of a convectively coupled Kelvin wave (CCKW). The observed formation of the nearly closed circulation on 10 September is well timed with the passage of this convectively active phase, a relationship that has been shown to hold true in cases of CCKW-TC interactions around the globe. Physically, the CCKW increases deep convection and aids in the generation of low-level relative vorticity on the cyclonic shear side of the low-level westerly wind anomalies, both of which serve to help organize the pre-Karl disturbance. Finally, the passage of the CCKW coincides with an equatorward surge of cold air and southerly winds in the lee of the Andes, triggered by a passing mid-latitude disturbance on 31 August. As the surge passes the equator on 7 September, little temperature perturbation remains with the surge, but terrain-channeled low-level flow acts to turn southerly flow into westerly flow south of the pre-Karl disturbance. By 8-9 September, anomalous westerly winds with the surge merge with and enhance the anomalous westerly winds associated with the CCKW passage, strengthening the low-level vorticity generation in the cyclonic shear of the merged CCKW-wind surge on the pre-Karl disturbance. However, despite this increase in vorticity and convection, the environment surrounding the pre-Karl disturbance remained unfavorable for several more days, with increased vertical wind shear and the convectively suppressed phase of a CCKW inhibiting further development before TC genesis occurred on 14 September. Despite this delayed development, the interplay of both mid-latitude and equatorial wave precursors likely contributed to the eventual genesis of TC Karl.

  16. The Structure and Dynamics of Coherent Vortices in the Eyewall Boundary Layer of Tropical Cyclones.

    NASA Astrophysics Data System (ADS)

    Stern, Daniel; Bryan, George

    2014-05-01

    The boundary layer within the eyewall of intense tropical cyclones has been shown to be both highly turbulent and to contain coherent small-scale (of order 1 km) vortices. Dropsonde observations have indicated that extreme updrafts of 10-25 m/s can occur in the lowest 2 km, sometimes as low as a few hundred meters above the sea surface. These updrafts are often collocated with or found very nearby to local extrema in horizontal wind speed, which sometimes exceed 100 m/s. A previous numerical study of Hurricane Isabel investigated updrafts that appeared to be analogous to those seen in the dropsondes, and it was shown that these updrafts were associated with coherent vortices, were confined to low-levels, and were not forced by buoyancy. A significant limitation of this previous work is that the vortices/updrafts were only marginally resolved. Here, the CM1 model is used to simulate intense tropical cyclones in an idealized framework, with horizontal grid spacing as fine as ~30 meters. At this grid spacing, the scales of the vortices (~500-1500 m) are clearly well resolved. By examining individual features and compositing over many updrafts, we find that there is a consistent structure and relationship between vorticity, vertical velocity, and near surface windspeeds. We quantitatively show that buoyancy is not responsible for the acceleration of strong boundary layer updrafts. Instead, the updrafts are forced by dynamical pressure gradients associated with strong gradients in the velocity fields. It is currently unknown whether dropsonde observations represent quasi-vertical profiles through the features, or if instead the sondes are horizontally advected through the features. Simulated dropsonde trajectories are used to answer this question, and to aid in the interpretation of the observed kinematic and thermodynamic profiles. In observations, these extreme updrafts are almost exclusively found in Category 4 and 5 hurricanes. We conduct simulations at varying intensity to investigate whether or not similar features exist in weaker storms. Finally, observations indicate that nearly all extreme updrafts are found in the left-of-shear semicircle. We conduct additional simulations with varying amounts of shear in order to better understand the mechanisms by which shear controls the spatial distribution of these features.

  17. Using Enabling Technologies to Advance Data Intensive Analysis Tools in the JPL Tropical Cyclone Information System

    NASA Astrophysics Data System (ADS)

    Knosp, B.; Gangl, M. E.; Hristova-Veleva, S. M.; Kim, R. M.; Lambrigtsen, B.; Li, P.; Niamsuwan, N.; Shen, T. P. J.; Turk, F. J.; Vu, Q. A.

    2014-12-01

    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 related to tropical cyclones. The TCIS has been supporting specific science field campaigns, such as the Genesis and Rapid Intensification Processes (GRIP) campaign and the Hurricane and Severe Storm Sentinel (HS3) campaign, by creating near real-time (NRT) data visualization portals. These portals are intended to assist in mission planning, enhance the understanding of current physical processes, and improve model data by comparing it to satellite and aircraft observations. The TCIS NRT portals allow the user to view plots on a Google Earth interface. To compliment these visualizations, the team has been working on developing data analysis tools to let the user actively interrogate areas of Level 2 swath and two-dimensional plots they see on their screen. As expected, these observation and model data are quite voluminous and bottlenecks in the system architecture can occur when the databases try to run geospatial searches for data files that need to be read by the tools. To improve the responsiveness of the data analysis tools, the TCIS team has been conducting studies on how to best store Level 2 swath footprints and run sub-second geospatial searches to discover data. The first objective was to improve the sampling accuracy of the footprints being stored in the TCIS database by comparing the Java-based NASA PO.DAAC Level 2 Swath Generator with a TCIS Python swath generator. The second objective was to compare the performance of four database implementations - MySQL, MySQL+Solr, MongoDB, and PostgreSQL - to see which database management system would yield the best geospatial query and storage performance. The final objective was to integrate our chosen technologies with our Joint Probability Density Function (Joint PDF), Wave Number Analysis, and Automated Rotational Center Hurricane Eye Retrieval (ARCHER) tools. In this presentation, we will compare the enabling technologies we tested and discuss which ones we selected for integration into the TCIS' data analysis tool architecture. We will also show how these techniques have been automated to provide access to NRT data through our analysis tools.

  18. Evaluation and Validation of Simulated CYGNSS Winds over Large Range of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Jelenak, Zorana; Chang, Paul; Soisuvarn, Seubson; Said, Faozi

    2015-04-01

    The CYclone Global Navigation Satellite System (CYGNSS) mission is the first satellite constellation demonstration of ocean surface wind retrievals utilizing the GPS reflection technique [1]. While CYGNSS is targeting retrievals in and around the tropical cyclone environment, it will be retrieving wind speeds in all weather conditions. The End-to-End (E2E) simulator was developed by the CYGNSS project to help assess engineering design impacts, develop and evaluate wind retrieval algorithms, and to help identify and address system risk areas. The CYGNSS E2E simulator takes sensor-based inputs such as the GPS satellite locations, CYGNSS satellite locations, the transmitter and receiver positions and orientations, and the antenna pattern, together with large non-uniform wind fields and produces simulated DDMs. These DDMs are then used within retrieval algorithms to produce observed winds. To assess the performance and error characteristics of CYGNSS wind measurements as well as to test different sensor configurations, measurements were simulated using E2E simulator and realistic, high-resolution wind fields from Hurricane Weather Research and Forecasting prediction model HWRF during 2010-2011 Atlantic and Pacific hurricane seasons. This resulted in simulated measurements for a total of 43 storms; 22 hurricanes, 17 tropical storms and 4 depressions. Wind speeds retrievals from simulated measurements were performed using retrieval algorithm developed at the University of Michigan [2]. To characterize algorithm performance and CYGNSS measurement capability CYGNSS wind retrievals were collocated in space and time with "truth" data. The "truth" data included HWRF, ASCAT and OSCAT scatterometer winds, and step frequency microwave radiometer (SFMR) aircraft measurements collected during hurricane reconnaissance flights. Wind speed retrieval error characteristics relative to wind speed ranges, measurement geometry, storm center position and NHC best track database were examined and validated against project science requirements document. The improved understanding of measurement and algorithm performances, derived from these analyses, led us to develop new quality flagging scheme with a goal of achieving a more robust wind product. The new flagging scheme has been proposed and implemented in final validation statistics. A summary of the analyses of these simulated data and flagging algorithm will be presented and discussed. References: [1] Ruf, C.S.; Gleason, S.; Jelenak, Z.; Katzberg, S.; Ridley, A.; Rose, R.; Scherrer, J.; Zavorotny, V. : The CYGNSS nanosatellite constellation hurricane mission; IEEE International Geoscience and Remote Sensing Symposium Proceedings, pp 214-216; July 2012 [2] Clarizia, M.P.; Ruf, C.S.; Jales, P.; Gommenginger, C.; Spaceborne GNSS-R minimum variance wind speed estimator; IEEE Transactions on Geoscience and Remote Sensing, pp 6829-6843; February 2014

  19. High Resolution Global Climate Modeling with GEOS-5: Intense Precipitation, Convection and Tropical Cyclones on Seasonal Time-Scales.

    NASA Technical Reports Server (NTRS)

    Putnam, WilliamM.

    2011-01-01

    In 2008 the World Modeling Summit for Climate Prediction concluded that "climate modeling will need-and is ready-to move to fundamentally new high-resolution approaches to capitalize on the seamlessness of the weather-climate continuum." Following from this, experimentation with very high-resolution global climate modeling has gained enhanced priority within many modeling groups and agencies. The NASA Goddard Earth Observing System model (GEOS-5) has been enhanced to provide a capability for the execution at the finest horizontal resolutions POS,SIOle with a global climate model today. Using this high-resolution, non-hydrostatic version of GEOS-5, we have developed a unique capability to explore the intersection of weather and climate within a seamless prediction system. Week-long weather experiments, to mUltiyear climate simulations at global resolutions ranging from 3.5- to 14-km have demonstrated the predictability of extreme events including severe storms along frontal systems, extra-tropical storms, and tropical cyclones. The primary benefits of high resolution global models will likely be in the tropics, with better predictions of the genesis stages of tropical cyclones and of the internal structure of their mature stages. Using satellite data we assess the accuracy of GEOS-5 in representing extreme weather phenomena, and their interaction within the global climate on seasonal time-scales. The impacts of convective parameterization and the frequency of coupling between the moist physics and dynamics are explored in terms of precipitation intensity and the representation of deep convection. We will also describe the seasonal variability of global tropical cyclone activity within a global climate model capable of representing the most intense category 5 hurricanes.

  20. A Comparison of Dynamical Seasonal Tropical Cyclone Predictions for the Australian and Western Pacific Regions

    NASA Astrophysics Data System (ADS)

    Shelton, Kay; Charles, Andrew; Nakaegawa, Toshiyuki; Hendon, Harry; Kuleshov, Yuriy

    2013-04-01

    The Australian Bureau of Meteorology (BoM) issues predictions of tropical cyclone (TC) activity in the Australian and South Pacific regions in the October before the TC season (November to April). Currently, these predictions utilise a statistical model based on the historical relationship between tropical cyclone activity and (i) sea surface temperature anomalies in the Equatorial Pacific (NINO3.4 region) and (ii) the Southern Oscillation Index over the past few decades. Variations in the El Niño-Southern Oscillation (ENSO)-TC relationship that are not contained within the historical record can lead to deficiencies in future predictions. The use of dynamical (physics-based) climate models (GCMs) offers an alternative to statistical TC prediction schemes. Any changes to the environment (whatever their character or cause) are incorporated in the analyses used to initialise a dynamical model. As part of the Pacific-Australia Climate Change Science and Adaptation Planning (PACCSAP) Program, BoM is developing dynamically-based seasonal TC predictions for the Australian, South Pacific and North-West Pacific regions. The seasonal TC predictions from two fully-coupled GCMs are evaluated and compared. These models are BoM's Predictive Ocean-Atmosphere Model for Australia (POAMA) and the Japan Meteorological Agency/Meteorological Research Institute Coupled GCM (JMA/MRI-CGCM). The resolution of POAMA's atmospheric component is T42 (~2.5° x 2.5°), while JMA/MRI-CGCM is T95 (~1.8° x 1.8°). Two TC tracking methods are employed and applied to both models to evaluate the influence of model composition and tracking technique on seasonal TC predictions. In the more traditional TC detection scheme TCs are identified where 850-hPa relative vorticity is a maximum (minimum in the Southern Hemisphere) and exceeds a certain threshold. Additionally, the 500-200-hPa thickness and the difference in maximum winds at 850 and 200 hPa are used to differentiate tropical from extratropical disturbances. A second TC detection scheme, developed at BoM for use with low resolution climate models, identifies local environments that are considered favourable for TCs to form and develop. This technique utilises the Okubo-Weiss-Zeta Parameter (OWZP), which isolates regions with low-deformation flow and large amplitude vorticity. Low-level humidity and vertical wind shear thresholds are also applied to ensure that only tropical disturbances are identified as TCs. Application of the OWZP technique to POAMA reveals TC-like disturbances with horizontal and vertical structure resembling those identified in other GCMs of similar resolution. The geographic distribution of genesis locations and the tracks of the disturbances are similar to those for observed TCs. The seasonal and interannual variability of the TC-like disturbances in POAMA is consistent with observations; however, too few disturbances are present in the Australian region. The modulation of the geographic distribution of the TC-like disturbances by ENSO is also consistent with observations. The suitability of the system for predicting TC activity for the Australian and South Pacific regions will be reported on, including an assessment of the predictability of large-scale environmental parameters favourable to TC development.

  1. How Well Do Global Climate Models Simulate the Variability of Atlantic Tropical Cyclones Associated with ENSO?

    NASA Technical Reports Server (NTRS)

    Wang, Hui; Long, Lindsey; Kumar, Arun; Wang, Wanqiu; Schemm, Jae-Kyung E.; Zhao, Ming; Vecchi, Gabriel A.; LaRow, Timorhy E.; Lim, Young-Kwon; Schubert, Siegfried D.; Shaevitz, Daniel A.; Camargo, Suzana J.; Henderson, Naomi; Kim, Daehyun; Jonas, Jeffrey A.; Walsh, Kevin J. E.

    2013-01-01

    The variability of Atlantic tropical cyclones (TCs) associated with El Nino-Southern Oscillation (ENSO) in model simulations is assessed and compared with observations. The model experiments are 28-yr simulations forced with the observed sea surface temperature from 1982 to 2009. The simulations were coordinated by the U.S. CLIVAR Hurricane Working Group and conducted with five global climate models (GCMs) with a total of 16 ensemble members. The model performance is evaluated based on both individual model ensemble means and multi-model ensemble mean. The latter has the highest anomaly correlation (0.86) for the interannual variability of TCs. Previous observational studies show a strong association between ENSO and Atlantic TC activity, as well as distinctions in the TC activities during eastern Pacific (EP) and central Pacific (CP) El Nino events. The analysis of track density and TC origin indicates that each model has different mean biases. Overall, the GCMs simulate the variability of Atlantic TCs well with weaker activity during EP El Nino and stronger activity during La Nina. For CP El Nino, there is a slight increase in the number of TCs as compared with EP El Nino. However, the spatial distribution of track density and TC origin is less consistent among the models. Particularly, there is no indication of increasing TC activity over the U.S. southeast coastal region as in observations. The difference between the models and observations is likely due to the bias of vertical wind shear in response to the shift of tropical heating associated with CP El Nino, as well as the model bias in the mean circulation.

  2. Re-examination of tropical cyclone formation in monsoon troughs over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Zong, Huijun; Wu, Liguang

    2015-07-01

    The monsoon trough (MT) is one of the large-scale patterns favorable for tropical cyclone (TC) formation over the western North Pacific (WNP). This study re-examines TC formation by treating the MT as a large-scale background for TC activity during May-October. Over an 11-year (2000-10) period, 8.3 TC formation events on average per year are identified to occur within MTs, accounting for 43.1% of the total TC formation events in the WNP basin. This percentage is much lower than those reported in previous studies. Further analysis indicates that TC formation events in monsoon gyres were included at least in some previous studies. The MT includes a monsoon confluence zone where westerlies meet easterlies and a monsoon shear line where the trade easterlies lie north of the monsoon westerlies. In this study, the large-scale flow pattern associated with TC formation in the MT is composited based on the reference point in the confluence zone where both the zonal and meridional wind components are zero with positive vorticity. While previous studies have found that many TCs form in the confluence zone, the composite analysis indicates that nearly all of the TCs formed in the shear region, since the shear region is associated with stronger low-level relative vorticity than the confluence zone. The prevailing easterly vertical shear of zonal wind and barotropic instability may also be conducive to TC formation in the shear region, through the development of synoptic-scale tropical disturbances in the MT that are necessary for TC formation.

  3. Tropical Cyclone Activity in Regional and Grid-Refined Global Simulations

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.

    2014-12-01

    Most electric power and transmission facilities in Japan operate for half a century or more, so it is important to ensure against general fatigue and damage from extreme weather and climate events. There is therefore a critical demand for useful assessments of the present weather and accurate predictions of future weather and climate. Tropical Cyclones (TCs) are among the most destructive weather phenomenon to the industry. This study compares simulated TC activity in regional climate simulations using the Weather Research and Forecasting (WRF) model and global climate simulations using the Model for Prediction Across Scales (MPAS) specifically to identify the benefits of global variable resolution simulation. Horizontal refinement to approximately 20km grid spacing over the Northwest Pacific is achieved through nesting for WRF and MPAS uses a variable resolution mesh. The ability of these two simulation approaches to capture TC activity is examined in single-year continuous simulations from May 2005 to April 2006. Compared to surface station and satellite derived rainfall datasets, tropical precipitation patterns are reproduced reasonably well by both models, but the annual precipitation totals are overestimated. Similarly, using an automated TC identification and tracking algorithm, results show that both models reproduce well TC genesis regions, tracks, wind-pressure relationships, and intensification rate, but TC frequencies are overestimated by both models. These results indicate that global variable resolution simulation is a suitable tool to study regional climate and TC activity. Future work will use MPAS to simulate longer periods of current and future climate to provide a unique view of the future change TC activity over Japan, tailored to the needs of the electric power industry.

  4. Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    NASA Technical Reports Server (NTRS)

    Mccaul, Eugene W., Jr.; Buechler, Dennis E.; Goodman, Steven J.; Cammarata, Michael

    2004-01-01

    Data from a single Weather Surveillance Radar-1988 Doppler (WSR-88D) and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak, including three tornadoes that reached F3 intensity, within Tropical Storm Beryl s remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 h. spawning tornadoes over a time period spanning approximately 6.5 h. Several other tornadic cells also exhibited great longevity, with cell lifetimes longer than ever previously documented in a landfalling tropical cyclone (TC) tornado event. This event is easily the most intense TC tornado outbreak yet documented with WSR-88Ds. Time-height analyses of the three strongest tornadic supercells are presented in order to document storm kinematic structure and to show how these storms appear at different ranges from a WSR-88D. In addition, cloud-to-ground (CG) lightning data are examined in Beryl s remnants. Although the tornadic cells were responsible for most of Beryl's CG lightning, their flash rates were only weak to moderate, and in all the tornadic storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced no detectable CG lightning at all. There is evidence that CG lightning rates decreased during the tornadoes, compared to 30-min periods before the tornadoes. A number of the storms spawned tornadoes just after producing their final CG lightning flashes. Contrary to the findings for flash rates, both peak currents and positive flash percentages were larger in Beryl's nontornadic storms than in the tornadic ones.

  5. Investigation on the Influence of the Column Ozone Anomaly on the Energetics of Tropical Cyclones Over NIO and Related Air-Sea Interaction

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Sutapa; Dutta, Debashree

    2014-09-01

    An investigation on the temporal and spatial variation of ozone using the total column ozone (TCO) values during the cyclonic activities over North Indian Ocean (NIO) is carried out during the period from 1997 to 2012. The stepwise variation of TCO during the passage of the tropical cyclones over the Bay of Bengal and the Arabian Sea of the NIO is examined. The anomalies in TCO are estimated at each step of the life span of the cyclones starting from the genesis to landfall stages. The result reveals that the TCO values are quite high prior to the formation of the depression over NIO; however, at the stage of cyclogenesis it decreases which, with the increase in the intensity of the cyclones, further decreases and becomes minimum near the coast during the landfall. The maximum negative anomaly in TCO is observed for maximum intensity of the tropical cyclones as well as during the landfall. The result further shows that when the cyclones die out after the landfall the TCO regains the normal value. It is further observed that the reduction in TCO enhances the accumulated cyclone energy over NIO. The result finally shows that, the higher the energy of the cyclones, the lower becomes the stratospheric warming, that is, the higher the stratospheric cooling.

  6. ATOVS microwave sounding observation cycling assimilation on a tropical cyclone case in 2012

    NASA Astrophysics Data System (ADS)

    Xi, Shuang; Dong, Peng-ming; Zhang, Peng; Ma, Gang; Qin, Dan-yu

    2014-11-01

    This study introduces the construction of the satellite observation cycling assimilation system in national satellite meteorological center (NSMC). A typhoon case (1209 Saola ) is chosen to be performed as a testing experiment to check the operation of the cycling assimilation, with a low resolution . Three experiments are designed: control, ATOVS microwave observation assimilation and forecasting with cold starting, assimilation and forecasting with warm starting. Compared with the cold start forecasting, cycling forecasting showed advance in describing more information of the Tropical Cyclones in detail. As for track and intensity prediction, both the two assimilation experiments were prior to control experiment. Especially, the cycling experiment is better than cold experiment in the first one day and third day and the day before landing, but not act well in its peak period, which may suggest that the model couldn't not match the description of the typhoon Saola at the full developing period or upgrading develop period, with the low resolution in the testing experiments, but also can demonstrate well when it develop slowly or in a relatively steady period.

  7. Landscape-scale analysis of wetland sediment deposition from four tropical cyclone events.

    PubMed

    Tweel, Andrew W; Turner, R Eugene

    2012-01-01

    Hurricanes Katrina, Rita, Gustav, and Ike deposited large quantities of sediment on coastal wetlands after making landfall in the northern Gulf of Mexico. We sampled sediments deposited on the wetland surface throughout the entire Louisiana and Texas depositional surfaces of Hurricanes Katrina, Rita, Gustav, and the Louisiana portion of Hurricane Ike. We used spatial interpolation to model the total amount and spatial distribution of inorganic sediment deposition from each storm. The sediment deposition on coastal wetlands was an estimated 68, 48, and 21 million metric tons from Hurricanes Katrina, Rita, and Gustav, respectively. The spatial distribution decreased in a similar manner with distance from the coast for all hurricanes, but the relationship with distance from the storm track was more variable between events. The southeast-facing Breton Sound estuary had significant storm-derived sediment deposition west of the storm track, whereas sediment deposition along the south-facing coastline occurred primarily east of the storm track. Sediment organic content, bulk density, and grain size also decreased significantly with distance from the coast, but were also more variable with respect to distance from the track. On average, eighty percent of the mineral deposition occurred within 20 km from the coast, and 58% was within 50 km of the track. These results highlight an important link between tropical cyclone events and coastal wetland sedimentation, and are useful in identifying a more complete sediment budget for coastal wetland soils. PMID:23185635

  8. Landscape-Scale Analysis of Wetland Sediment Deposition from Four Tropical Cyclone Events

    PubMed Central

    Tweel, Andrew W.; Turner, R. Eugene

    2012-01-01

    Hurricanes Katrina, Rita, Gustav, and Ike deposited large quantities of sediment on coastal wetlands after making landfall in the northern Gulf of Mexico. We sampled sediments deposited on the wetland surface throughout the entire Louisiana and Texas depositional surfaces of Hurricanes Katrina, Rita, Gustav, and the Louisiana portion of Hurricane Ike. We used spatial interpolation to model the total amount and spatial distribution of inorganic sediment deposition from each storm. The sediment deposition on coastal wetlands was an estimated 68, 48, and 21 million metric tons from Hurricanes Katrina, Rita, and Gustav, respectively. The spatial distribution decreased in a similar manner with distance from the coast for all hurricanes, but the relationship with distance from the storm track was more variable between events. The southeast-facing Breton Sound estuary had significant storm-derived sediment deposition west of the storm track, whereas sediment deposition along the south-facing coastline occurred primarily east of the storm track. Sediment organic content, bulk density, and grain size also decreased significantly with distance from the coast, but were also more variable with respect to distance from the track. On average, eighty percent of the mineral deposition occurred within 20 km from the coast, and 58% was within 50 km of the track. These results highlight an important link between tropical cyclone events and coastal wetland sedimentation, and are useful in identifying a more complete sediment budget for coastal wetland soils. PMID:23185635

  9. Thermodynamic characteristics of tropical cyclones with rapid intensity change over the coastal waters of China

    NASA Astrophysics Data System (ADS)

    Yu, Yubin; Yao, Xiuping

    2011-08-01

    In order to investigate the different thermodynamic mechanisms between rapid intensifying (RI) and rapid weakening (RW) tropical cyclones (TCs), the thermodynamic structures of two sets of composite TCs are analyzed based on the complete-form vertical vorticity tendency equation and the NCEP/NCAR reanalysis data. Each composite is composed of five TCs, whose intensities change rapidly over the coastal waters of China. The results show that the maximum apparent heating source Q 1 exists in both the upper and lower troposphere near the RI TC center, and Q 1 gets stronger at the lower level during the TC intensification period. But for the RW TC, the maximum Q 1 exists at the middle level near the TC center, and Q 1 gets weaker while the TC weakens. The maximum apparent moisture sink Q 2 lies in the mid troposphere. Q 2 becomes stronger and its peak-value height rises while TC intensifies, and vice versa. The increase of diabatic heating with height near the TC center in the mid-upper troposphere and the increase of vertical inhomogeneous heating near the TC center in the lower troposphere are both favorable to the TCs' rapid intensification; otherwise, the intensity of the TC decreases rapidly.

  10. Modulation of Environmental Factors on Abnormal Track and Intensity of Tropical Cyclone Nargis (2008)

    NASA Astrophysics Data System (ADS)

    Wang, D.; Wang, C.; Yang, L.; Li, W.

    2010-12-01

    Tropical cyclone Nargis made landfall in Myanmar on 2 May, 2008, brought this country storm surge, flood and significant death toll. Abnormal features were displayed during the life cycle of Nargis, including earlier season occurrence, rare eastward motion, rapid intensification, and torrential rain. This study is to investigate circulation modulation at high latitude (including polar region) on Nargis’ track, and the associated favorable atmospheric conditions during Nargis’ rapid intensification period. A hypothesis about non-local air-sea interaction effect on rapid intensification is also raised. Our analysis indicates that, locally, a synoptic ridge system in India and the north invasion of low latitude westerly together contributed to steering Nargis eastward after its recurvature. Both of them result from the circulation adjustment at high latitude. During the rapid intensification period, such westerly in the Bay of Bengal was also in favor of providing more water vapor to Nargis, which permitted more latent heat to be released for rapid intensification. It seems that, apart from the heat supplied from the ocean beneath the core of Nargis, heat exchange with the upper layer of the neighboring ocean of the Andaman Sea contributed to Nargis’ rapid intensification prior to its landfalling.

  11. Impacts of assimilating various remotely sensed atmospheric parameters on WRF's tropical cyclone prediction skill

    NASA Astrophysics Data System (ADS)

    Ren, D.; Lynch, M. J.; Le Marshall, J.; Leslie, L. M.; Yu, F.; Zhang, G.

    2014-12-01

    Assimilating remotely sensed atmospheric parameters are critical for improving numerical weather prediction model skill, and especially for the prediction of tropical cyclone (TC) activities. The model skill is assessed by comparison with IBTRACs. In this talk, we will present results recently obtained using the weather research and forecasting data assimilation (WRF_DA) code. In the four TC cases studied (between 2003 and 2009), QuikSCAT measured near surface wind vectors (within a 6-hour assimilation window centered at model initiaisationl time) are assimilated. We further assimilated Infrared Atmospheric Sounding Interferometer (IASI) clear sky radiance and SSM/I measured total precipitable water vapour. By comparing with the control case (without assimilating any remote sensing data), the information content and impact of individual data sources are estimated. Possible use of cloudy and cloud contaminated radiances also will be assessed. Since the lifetime of a satellite platform is limited (~10 years), we further discuss a generic quality control scheme and an objective scheme of channel selection. This differs from the WRF_DA default procedure. An efficient method of obtaining bias correction coefficients are presented together with updating these coefficients in the prediction cycle.

  12. North American Tropical Cyclone Landfall and SST: A Statistical Model Study

    NASA Technical Reports Server (NTRS)

    Hall, Timothy; Yonekura, Emmi

    2013-01-01

    A statistical-stochastic model of the complete life cycle of North Atlantic (NA) tropical cyclones (TCs) is used to examine the relationship between climate and landfall rates along the North American Atlantic and Gulf Coasts. The model draws on archived data of TCs throughout the North Atlantic to estimate landfall rates at high geographic resolution as a function of the ENSO state and one of two different measures of sea surface temperature (SST): 1) SST averaged over the NA subtropics and the hurricane season and 2) this SST relative to the seasonal global subtropical mean SST (termed relSST). Here, the authors focus on SST by holding ENSO to a neutral state. Jackknife uncertainty tests are employed to test the significance of SST and relSST landfall relationships. There are more TC and major hurricane landfalls overall in warm years than cold, using either SST or relSST, primarily due to a basinwide increase in the number of storms. The signal along the coast, however, is complex. Some regions have large and significant sensitivity (e.g., an approximate doubling of annual major hurricane landfall probability on Texas from -2 to +2 standard deviations in relSST), while other regions have no significant sensitivity (e.g., the U.S. mid-Atlantic and Northeast coasts). This geographic structure is due to both shifts in the regions of primary TC genesis and shifts in TC propagation.

  13. Does it make sense to modify tropical cyclones? A decision-analytic assessment.

    PubMed

    Klima, Kelly; Morgan, M Granger; Grossmann, Iris; Emanuel, Kerry

    2011-05-15

    Recent dramatic increases in damages caused by tropical cyclones (TCs) and improved understanding of TC physics have led DHS to fund research on intentional hurricane modification. We present a decision analytic assessment of whether it is potentially cost-effective to attempt to lower the wind speed of TCs approaching South Florida by reducing sea surface temperatures with wind-wave pumps. Using historical data on hurricanes approaching South Florida, we develop prior probabilities of how storms might evolve. The effects of modification are estimated using a modern TC model. The FEMA HAZUS-MH MR3 damage model and census data on the value of property at risk are used to estimate expected economic losses. We compare wind damages after storm modification with damages after implementing hardening strategies protecting buildings. We find that if it were feasible and properly implemented, modification could reduce net losses from an intense storm more than hardening structures. However, hardening provides "fail safe" protection for average storms that might not be achieved if the only option were modification. The effect of natural variability is larger than that of either strategy. Damage from storm surge is modest in the scenario studied but might be abated by modification. PMID:21506599

  14. Tropical cyclone warm core analyses with FY-3 microwave temperature sounder data

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Bai, Jie; Zhang, Wenjun; Yan, Jun; Zhou, Zhuhua

    2014-05-01

    Space-borne microwave instruments are well suited to analyze Tropical Cyclone (TC) warm core structure, because certain wavelengths of microwave energy are able to penetrate the cirrus above TC. With the vector discrete-ordinate microwave radiative transfer model, the basic atmospheric parameters of Hurricane BOB are used to simulate the upwelling brightness temperatures on each channel of the Microwave Temperature Sounder (MWTS) onboard FY-3A/3B observation. Based on the simulation, the characteristic of 1109 super typhoon "Muifa" warm core structure is analyzed with the MWTS channel 3. Through the radiative and hydrostatic equation, TC warm core brightness temperature anomalies are related to surface pressure anomalies. In order to correct the radiation attenuation caused by MWTS scan geometric features, and improve the capability in capturing the relatively complete warm core radiation, a proposed algorithm is devised to correct the bias from receiving warm core microwave radiation, shows similar time-variant tendency with "Muifa" minimal sea level pressure as described by TC best track data. As the next generation of FY-3 satellite will be launched in 2012, this method will be further verified

  15. Ecosystem effects of a tropical cyclone on a network of lakes in northeastern North America.

    PubMed

    Klug, Jennifer L; Richardson, David C; Ewing, Holly A; Hargreaves, Bruce R; Samal, Nihar R; Vachon, Dominic; Pierson, Donald C; Lindsey, Amanda M; O'Donnell, David M; Effler, Steven W; Weathers, Kathleen C

    2012-11-01

    Here we document the regional effects of Tropical Cyclone Irene on thermal structure and ecosystem metabolism in nine lakes and reservoirs in northeastern North America using a network of high-frequency, in situ, automated sensors. Thermal stability declined within hours in all systems following passage of Irene, and the magnitude of change was related to the volume of water falling on the lake and catchment relative to lake volume. Across systems, temperature change predicted the change in primary production, but changes in mixed-layer thickness did not affect metabolism. Instead, respiration became a driver of ecosystem metabolism that was decoupled from in-lake primary production, likely due to addition of terrestrially derived carbon. Regionally, energetic disturbance of thermal structure was shorter-lived than disturbance from inflows of terrestrial materials. Given predicted regional increases in intense rain events with climate change, the magnitude and longevity of ecological impacts of these storms will be greater in systems with large catchments relative to lake volume, particularly when significant material is available for transport from the catchment. This case illustrates the power of automated sensor networks and associated human networks in assessing both system response and the characteristics that mediate physical and ecological responses to extreme events. PMID:23016881

  16. Seasonal prediction for tropical cyclone frequency around Taiwan using teleconnection patterns

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Wu, Chun-Chieh; Wang, Yuqing

    2014-05-01

    In this study, a statistical model is developed to predict the frequency of tropical cyclones (TCs) that influence Taiwan in boreal summer. Predictors are derived from large-scale environments from February to May in six regions, including four atmospheric circulation predictors over the western sea and eastern sea of Australia, the subtropical western North Pacific (SWNP), and the eastern sea of North America, and two sea surface temperature predictors in the Southeast Indian Ocean and the North Atlantic. The statistical model is verified based on statistical cross-validation tests and by contrasting the differences in the large-scale environments between high and low TC frequency years hindcasted by the model. The results show the relationships of two atmospheric circulation predictors and one SST predictor around Australia with Antarctic Oscillation (AAO) pattern, as well as the relationships of those in the SWNP and around eastern sea of North America with Pacific/North American teleconnection (PNA) pattern. When the anomalous anticyclone around Australia (positive AAO pattern) and the one over the region from eastern sea of North America and the Aleutian Islands to the SWNP (negative PNA pattern) are both strengthened from February, the trade wind in the equatorial Pacific is intensified and consequently plays an important role in steering TCs towards Taiwan during boreal summer.

  17. PDO modulation of ENSO effect on tropical cyclone rapid intensification in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Wang, Xidong; Liu, Hailong

    2015-03-01

    This study investigates how the Pacific Decadal Oscillation (PDO) modulates the effect of El Niño/Southern Oscillation (ENSO) on tropical cyclone rapid intensification (RI) in the western North Pacific. The analysis shows that the interannual relationship between ENSO and annual RI number in warm PDO phases is strong and statistically significant. In cold PDO phases, however, there is no significant correlation between ENSO and RI on the interannual timescale. The enhancement of the interannual ENSO-RI relationship in warm PDO phases is mainly attributable to the change of the environmental vertical wind shear. The PDO in warm (cold) phases can strengthen (weaken) an El Niño event to increase (reduce) the effects of the warm pool of water over the equatorial Pacific in typhoon season by local diabatic heating. El Niño events are accompanied by the stronger Walker circulation in the equatorial Pacific in the warm PDO phase than in the cold PDO phase. In contrast, the Walker circulation pattern and amplitude associated with La Niña events is less affected by the alternate PDO phase. This tends to make the atmospheric response to ENSO stronger (weaker) in warm (cold) PDO phase, and so is the atmospheric teleconnection of ENSO. Our results indicate that the stratification of ENSO-based statistical RI forecast by the PDO can greatly improve the accuracy of statistical RI predictions.

  18. Prehistorical tropical cyclones inferred from washover deposits in the Gulf of Exmouth (W Australia)

    NASA Astrophysics Data System (ADS)

    May, Simon Matthias; Brill, Dominik; Leopold, Matthias; Callow, Nik; Engel, Max; Pint, Anna; Scheffers, Anja; Brückner, Helmut

    2015-04-01

    The NW Australian coast is impacted by 1-2 tropical cyclones (TCs) making landfall per year, and ten historical tsunamis are recorded since 1858. Notwithstanding, little is known about the geological imprint of both (pre)historical TCs and tsunamis in NW Australia in general. Past coastal flooding events may be inferred from geomorphic and sedimentary archives, i.e. in the form of particular landforms (beach ridges, washover fans), deposits (washover sediments in lagoons) or erosional features. Here we present new data on the sedimentology and chronostratigraphy of prehistorical washover events found in geological archives in the NW part of Western Australia. Along the W coast of the Exmouth Gulf, distinct lobate washover fans consist of shell debris layers, sand, coarse coral fragments and entire shells and exhibit delta-type sedimentation patterns. Using ground penetrating radar, unmanned aerial vehicle survey techniques as well as geomorphological and sedimentological investigations, multiple reactivation of the washover fans due to strong TCs is inferred from their complex pattern of accumulation and incision and a minimum of three palaeosols. Each of the palaeosols indicate one major depositional event and a subsequent period of geomorphological stability. Our study aims at (i) providing a detailed characterization of the washover fans' geomorphology and stratigraphical architecture; (ii) documenting the depositional processes involved in the formation of the fans; and (iii) presenting a consistent OSL-based chronostratigraphy spanning the last ~2000 a, showing how OSL can be a key in establishing late Holocene event chronologies.

  19. Predictability of Atlantic tropical cyclones in the GFDL HiRAM model

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Zhang, Gan; Peng, Melinda S.; Chen, Jan-Huey; Lin, Shian-Jiann

    2015-04-01

    The hindcasts of the Geophysical Fluid Dynamics Laboratory (GFDL) High-Resolution Atmospheric Model (HiRAM), which skillfully predicted the interannual variability of Atlantic tropical cyclone (TC) frequency, were analyzed to investigate what key circulation systems a model must capture in order to skillfully predict TCs. The HiRAM reproduced the leading empirical orthogonal function mode (M1) of the interannual variability of the Atlantic Hadley circulation and its impacts on environmental conditions. M1 represents the variability of the Intertropical Convergence Zone (ITCZ) intensity and width, and the predictability of Atlantic TCs can be explained by the lag correlation between M1 and SST in preceding months. Although the ITCZ displacement was not well predicted by the HiRAM hindcasts, it does not affect the prediction of the basin-wide hurricane count. The analyses suggest that the leading mode of the variability of the regional Hadley circulation can serve as a useful metric to evaluate the performance of global models in TC seasonal prediction.

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

    NASA Technical Reports Server (NTRS)

    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. Enhanced western North Pacific tropical cyclone activity in May in recent years

    NASA Astrophysics Data System (ADS)

    Xu, Shibin; Wang, Bin

    2014-05-01

    The tropical cyclone (TC) power dissipation index (PDI) in May over the western North Pacific (WNP) region shows a remarkable increase from the pre-1999 years (1979-1999) to the post-1999 years (2000-2011). Both increased TC numbers and enhanced TC intensity contributed to the change in the PDI. The averaged TC number in May increased from 1.05 per year in the pre-1999 years to 1.75 per year in the post-1999 years. In particular, the number of intense typhoon goes up from 0.14 per year to 0.83 per year, implying a sharp increase of TC intensity. Examination of the large scale background circulation in May shows that the epochal increase of TC number is caused by a significant increase of the genesis potential index (GPI), which has increased by about 33 % from the first (1979-1998) to the second (1999-2011) epoch over the TC genesis region (110°E-160°E, 5°N-20°N). The higher TC intensity is related to the increased maximum potential intensity and reduced TC ambient vertical wind shear in the second epoch. These decadal changes in background conditions over the WNP are the results of the enhanced summer monsoon in May over the both South Asia and South China Sea.

  2. The interannual relationship between MJO activity and tropical cyclone genesis in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Tsuboi, Aya; Takemi, Tetsuya

    2014-12-01

    The present study investigated the relationship between the interannual variations of Madden-Julian Oscillation (MJO) and tropical cyclone genesis (TCG) over the Indian Ocean during the October-November-December season by conducting statistical analyses with the use of 33-year reanalysis data. Through dividing the 33-year period into the active year and the non-active year of MJO, we identified the characteristics of TCG in the active and the non-active year. Environmental conditions for TCG under the influence of the MJO activity were diagnosed by an empirical index, Genesis Potential Index (GPI). It was shown that TCG events over the Indian Ocean in the active year are significantly increased when the convectively active phase of MJO develops over the Indian Ocean and the Maritime Continent. GPI in the active (non-active) year showed positive (negative) anomaly over almost the whole Indian Ocean. In addition, TCG is enhanced (suppressed) in the area of positive (negative) GPI anomaly. Diagnosing the factors constituting GPI showed that relative humidity and vertical velocity have more pronounced contributions than the other factors of GPI. The present analyses demonstrate that the activity of MJO has an influence on the inter-annual relationship of TCG through the modulation of environmental conditions.

  3. Impact of intraseasonal oscillation on the tropical cyclone track in the South China Sea

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Du, Yan; Wang, Dongxiao; Wang, Chunzai; Wang, Xin

    2015-03-01

    This study investigates the impact of the intraseasonal oscillation (ISO) on tropical cyclone (TC) tracks in the South China Sea (SCS) during 1970-2010. About one third of TCs in the SCS move eastward, while the other two thirds move westward. In the TC genesis peak seasons of June-October (JJASO), the westward moving TCs are controlled by the background TC steering flow of easterly, and the eastward moving TCs by the TC steering flow induced by the ISO. The outgoing longwave radiation and wind fields show that the eastward moving TCs were mostly along the main axis of strong TC steering flow anomaly of westerly associated with the ISO, while the westward moving TCs were only weakly associated with the ISO. An experiment performed with a simple two-level model further confirmed the result. The interannual variation of TC tracks in the SCS is also discussed. It is found that the steering flow anomalies in the SCS mostly favor eastward moving TCs in central Pacific (CP) El Niño and eastern Pacific (EP) El Niño years. However, the eastward flow anomalies are too weak to have strong influence on the majority of the TCs. During La Niña years, TCs in the SCS tend to move westward, possibly related to the westward steering flow anomalies.

  4. Reexamination of the influence of ENSO on landfalling tropical cyclones in Korea

    NASA Astrophysics Data System (ADS)

    Ho, Chang-Hoi; Kim, Hyeong-Seog

    2011-11-01

    This study examines the influence of the El Niño-Southern Oscillation (ENSO) on the frequency of landfalling tropical cyclones (TCs) in the Korean Peninsula during the TC season, June through October, of the years 1951-2010. An ENSO year is defined when the seasonal mean of the NINO3.4 sea surface temperature (SST) anomalies is greater/less than the typical seasonal mean by 0.5°C. The overall results of this study support that ENSO does not affect the landfalling TCs in Korea; the mean frequencies of the TC landfalls (influences) during El Niño and La Niña calculated over the entire analysis period are 1.1 (3.3) and 1.2 (3.0), respectively. The variations in the basin-wide distribution of TCs show that the influence of ENSO on TC distribution is extended over southeastern Japan with no significant signals coming from over the Korean Peninsula and the East China Sea. The change in the intensity of the landfalling TCs in the Korean Peninsula due to ENSO leads to the same conclusion as that in the frequency of the landfalling TCs. In addition, the same conclusion is obtained when the TC season duration is expanded to include the entire year and when different definitions of the ENSO years (e.g., based on the preceding or following winter NINO3.4 SST anomalies) are selected for analysis.

  5. Impacts of Air-Sea Interaction on Tropical Cyclone Track and Intensity

    NASA Technical Reports Server (NTRS)

    Wu, Liguang; Wang, Bin; Braun, Scott A.

    2004-01-01

    The influence of hurricane-ocean coupling on intensity and track of tropical cyclones (TCs) is investigated through idealized numerical experiments using a coupled hurricane-ocean model. The focus is placed on how air-sea interaction affects TC tracks and intensity. It is found that the symmetric sea surface temperature (SST) cooling is primarily responsible for the TC weakening in the coupled experiments because the induced asymmetric circulation associated with the asymmetric SST anomalies is weak and shallow. The track difference between the coupled and fixed SST experiments is generally small because of the competing processes. One is associated with the modified TC asymmetries. The asymmetric SST anomalies - weaken the surface fluxes in the rear and enhance the fluxes in the front. As a result, the enhanced diabatic heating is located on the southern side for a westward-moving TC, tending to shift the TC southward. The symmetric SST anomalies weakens the TC intensity and thus the dymmetrization process, leading to more prominent TC asymmetries. The other is associated with the weakening of the beta drift resulting from the weakening of the TC outer strength. In the coupled experiment, the weakening of the beta drift leads to a more northward shift. By adjusting the vortex outer strength of the initial vortices, the beta drift can vary while the effect of air-sea interaction changes little. Two types of track differences simulated in the previous numerical studies are obtained.

  6. A stochastic model for tropical cyclone tracks based on Reanalysis data and GCM output

    NASA Astrophysics Data System (ADS)

    Ito, K.; Nakano, S.; Ueno, G.

    2014-12-01

    In the present study, we try to express probability distribution of tropical cyclone (TC) trajectories estimated on the basis of GCM output. The TC tracks are mainly controlled by the atmospheric circulation such as the trade winds and the Westerlies as well as are influenced to move northward by the Beta effect. The TC tracks, which calculated with trajectory analysis, would thus correspond to the movement of TCs due to the atmospheric circulation. Comparing the result of the trajectory analysis from reanalysis data with the Best Track (BT) of TC in the present climate, the structure of the trajectory seems to be similar to the BT. However, here is a significant problem for the calculation of a trajectory in the reanalysis wind field because there are many rotation elements including TCs in the reanalysis data. We assume that a TC would move along the steering current and the rotations would not have a great influence on the direction of moving. We are designing a state-space model based on the trajectory analysis and put an adjustment parameter for the moving vector. Here, a simple track generation model is developed. This model has a possibility to gain the probability distributions of calculated TC tracks by fitting to the BT using data assimilation. This work was conducted under the framework of the "Development of Basic Technology for Risk Information on Climate Change" supported by the SOUSEI Program of the Ministry of Education, Culture, Sports, Science, and Technology.

  7. The effects of vortex structure and vortex translation on the tropical cyclone boundary layer wind field

    NASA Astrophysics Data System (ADS)

    Williams, Gabriel J.

    2015-03-01

    The effects of vortex translation and radial vortex structure in the distribution of boundary layer winds in the inner core of mature tropical cyclones are examined using a high-resolution slab model and a multilevel model. It is shown that the structure and magnitude of the wind field (and the corresponding secondary circulation) depends sensitively on the radial gradient of the gradient wind field above the boundary layer. Furthermore, it is shown that vortex translation creates low wave number asymmetries in the wind field that rotate anticyclonically with height. A budget analysis of the steady state wind field for both models was also performed in this study. Although the agradient force drives the evolution of the boundary layer wind field for both models, it is shown that the manner in which the boundary layer flow responds to this force differs between the two model representations. In particular, the inner core boundary layer flow in the slab model is dominated by the effects of horizontal advection and horizontal diffusion, leading to the development of shock structures in the model. Conversely, the inner core boundary layer flow in the multilevel model is primarily influenced by the effects of vertical advection and vertical diffusion, which eliminates shock structures in this model. These results further indicate that special care is required to ensure that qualitative applications from slab models are not unduly affected by the neglect of vertical advection. This article was corrected on 31 MAR 2015. See the end of the full text for details.

  8. Eastern Pacific tropical cyclones intensified by El Niño delivery of subsurface ocean heat.

    PubMed

    Jin, F-F; Boucharel, J; Lin, I-I

    2014-12-01

    The El Niño Southern Oscillation (ENSO) creates strong variations in sea surface temperature in the eastern equatorial Pacific, leading to major climatic and societal impacts. In particular, ENSO influences the yearly variations of tropical cyclone (TC) activities in both the Pacific and Atlantic basins through atmospheric dynamical factors such as vertical wind shear and stability. Until recently, however, the direct ocean thermal control of ENSO on TCs has not been taken into consideration because of an apparent mismatch in both timing and location: ENSO peaks in winter and its surface warming occurs mostly along the Equator, a region without TC activity. Here we show that El Niño--the warm phase of an ENSO cycle--effectively discharges heat into the eastern North Pacific basin two to three seasons after its wintertime peak, leading to intensified TCs. This basin is characterized by abundant TC activity and is the second most active TC region in the world. As a result of the time involved in ocean transport, El Niño's equatorial subsurface 'heat reservoir', built up in boreal winter, appears in the eastern North Pacific several months later during peak TC season (boreal summer and autumn). By means of this delayed ocean transport mechanism, ENSO provides an additional heat supply favourable for the formation of strong hurricanes. This thermal control on intense TC variability has significant implications for seasonal predictions and long-term projections of TC activity over the eastern North Pacific. PMID:25471884

  9. Saharan Air and Atlantic Tropical Cyclone Suppression From a Global Modeling Perspective

    NASA Technical Reports Server (NTRS)

    Reale, O.; Lau, W. K. M.; daSilva, A.; Kim, K.-M.

    2007-01-01

    During summer 2006, the NASA African Monsoon Multidisciplinary Analysis (NAMMA) organized a field campaign in Africa called Special Observation Period (SOP-3), in which scientists in the field were involved in a number of surface network and aircraft measurements. One of the scientific goals of the campaign was to understand the nature and causes for tropical cyclogenesis originating out of African Easterly Waves (AEWs, westward propagating atmospheric disturbances sometimes associated with precursors of hurricanes), and the role that the Saharan Air Layer (SAL, a hot and dry air layer advecting large amounts of dust) can play in the formation or suppression of tropical cyclones. During the NAMMA campaign a high-resolution global model, the NASA GEOS-5, was operationally run by the NASA Global Modeling and Assimilation Office (GMAO) in support to the mission. The daily GEOS-5 forecasts were found to be very useful by decision-making scientists in the field as an aid to discriminate between developing and non-developing AEWs and plan the flight tracks. In the post-event analyses which were performed mostly by the Goddard Laboratory for Atmospheres, two events were highlighted: a non-developing AEW which appeared to have been suppressed by Saharan air, compared to a developing AEW which was the precursor of hurricane Helene. Both events were successfully predicted by the GEOS-5 during the real-time forecasts provided in support to the mission. In this work it is found that very steep moisture gradients and a strong thermal dipole, with relatively warm air in the mid-troposphere and cool air below, are associated with SAL in both the GEOS-5 forecasts and the NCEP analyses, even at -great distance- from the Sahara. The presence of these unusual thermodynamic features over the Atlantic Ocean, at several thousands of kilometers from the African coastline, is suggestive that SAL mixing is very minimal and that the model's capability of retaining the different properties of air masses during transport are important to represent effectively the role of dry air intrusions in the tropical circulation.

  10. Plant Carbonate Fossils from the Ephemeral Pond Domain in South Texas/NE Mexico Yield a Record of Tropical Cyclone Activity: Oxygen Isotopes

    NASA Astrophysics Data System (ADS)

    Lawrence, J. R.; Maddocks, R.; Slowey, N. C.; Roark, E.

    2013-05-01

    Tropical cyclones produce rain with anomalously low oxygen isotope ratios. When dry ponds suddenly receive a large influx of this rainwater, algal plants known as "Charo" grow rapidly and produce desiccation resistant seeds covered by a carbonate coating. The oxygen isotopic composition of the carbonate reflects the presence of tropical cyclone water. A sediment core was taken in 2010 and pond waters were collected. Three tropical cyclones flooded the pond that year. The pond waters exhibited low isotope ratios that gradually rose as evaporation took place over the following days. Carbonate coated seeds "Charo" were separated from the top centimeter of the core. Two of the analyzed samples exhibited distinctly low isotope ratios indicating that the pond had been flooded with water from tropical cyclones at least twice. Additional isotopic analyses of carbonate coating from the seeds deeper in the core are in progress. The quantity of carbonate coating the seeds is more than adequate for obtaining lead 210 and carbon 14 dates. The main objective of our study is to produce a longterm record of tropical cyclone activity in the South Texas / Northeast Mexico region.

  11. Tropical cyclone hazards and warning and disaster mitigation systems in India

    Microsoft Academic Search

    Porathur V Joseph

    1994-01-01

    The main features of a cyclone that cause death and destruction are: (1) Storm surge, a rapid increase in sea level along\\u000a the coast, primarily caused by the strong surface wind field of the cyclone as it approaches the coast, (2) the violent sustained\\u000a wind and wind gusts and cyclone-spawned tornadoes, and (3) the heavy rain and consequent flooding. The

  12. Small-scale field-aligned currents caused by tropical cyclones as observed by the SWARM satellites above the ionosphere

    NASA Astrophysics Data System (ADS)

    Aoyama, T.; Iyemori, T.; Nakanishi, K.

    2014-12-01

    We present case studies of small-scale magnetic fluctuations above typhoons, hurricanes and cyclones as observed by the swarm constellation. It is reported lately that AGWs(atmospheric gravity waves) generated by meteorological phenomena in the troposphere such as typhoons and tornadoes, large earthquakes and volcanic eruptions propagate to the mesosphere and thermosphere. We observe them in various forms(e.g. airglows, ionospheric disturbances and TEC variations). We are proposing the following model. AGWs caused by atmospheric disturbances in the troposphere propagate to the ionospheric E-layer, drive dynamo action and generate field-aligned currents. The satellites observe magnetic fluctuations above the ionosphere. In this presentation, we focus on cases of tropical cyclone(hurricanes in North America, typhoons in North-West Pacific).

  13. Analysis of cross-hemispheric influences on the monsoon trough and tropical cyclone genesis during FGGE and diurnal subsidence differences

    NASA Technical Reports Server (NTRS)

    Gray, W. M.; Lee, C. S.

    1985-01-01

    For a number of years our project has been studying the cross-equatorial (winter to summer hemisphere) processs that can lead to the day-to-day alterations in the strength of the monsoon trough. These processes are also related to the genesis and intensification of tropical storms. The cross-hemispheric processes that occurred during the FGGE year are currently being studied with the use of the ECMWF analysis. How the winter hemisphere can affect low level cold surge penetration across the equator following cold front passage, and how upper tropospheric anticyclones of the winter hemisphere can produce an intensification of a tropical cyclone of the opposite hemisphere is described. ECMWF analysis of the 00Z versus 12Z diurnal difference in the clear region (10 deg diameter) subsidence occurring in the subtropical Pacific Ocean during FGGE is presented. The general reliability of the FGGE ECMWF analysis with regard to the specification of the large scale structure of tropical cyclones is shown.

  14. Variability of Sea Surface Temperature Response to Tropical Cyclones along the NEC Bifurcation Latitude

    NASA Astrophysics Data System (ADS)

    Fernandez, I.; Villanoy, C. L.

    2013-12-01

    The east of the Philippines serves as an entry point to an annual average of 20 tropical cyclones. The ocean is dynamic where the North Equatorial Current (NEC) bifurcates into the Kurushio Current to the north and Mindanao Current to the south. The displacement and intensity of NEC bifurcation in the region varies seasonally and interannually driven by local monsoons and ENSO. The variability of the NEC bifurcation latitude may alter the origins of the Kuroshio and modify the sea surface temperature field, which can alter the strength of the typhoons and upper ocean response. This paper aims to characterize the variability of Sea Surface Temperature (SST) Response to Tropical Cyclones along with the NEC Bifurcation latitude using daily merged product of the TRMM Microwave Imager (TMI) and Advanced Microwave Scanning Radiometer (AMSR-E), Sea Surface Height (SSH) and SSH Anomaly (SSHA) from AVISO and background climatological D26 (depth of 26 °C) and T100 (depth integrated temperature up to 100 meters) from ARGO profiles and CTD data from WOA09 from 2003 to 2012. SSH measurements from this period were used as a proxy for determining the bifurcation latitude (YB). Characteristics of the meridional distribution from 0° to 30°N of D26 is homogenous along 10-15°N. Monthly mean D26 along 10-15°N, 125-145°E shows high correlation with YB . Variations of the D26 and T100 showed deepening and warming along with YB. Two regions were derived from meridional distribution of T100 namely BSouth (<15°N) where background climatological condition is warm all throughout the year with deep D26 and BNorth (>15°N), where background climatological condition is shallow (D26) and varies seasonally. These regions where used to compare variability with respect to SST recovery time and the SST maximum change (?SSTmax) along with other factors such as TCs translation speed (TS) and intensity based on the Saffir-Simpson Hurricane Scale. Results showed that in both regions SST Recovery time is described as fast (<= 5day) when ?SSTmax is less than 1°C. Also, slow-moving TCs (TS < 4 m/s) is associated with maximum change in temperature and most often with longer Recovery time (>5days). Difference between both regions can be described with respect to the ?SSTmax. Higher ?SSTmax of up to 7°C was observed on BNorth which can be attributed to colder water (Temp < 26) brought up to surface given a shallow D26 layer. Moreover, the presence of cold-core eddies (SSHA <0) contributes to higher maximum cooling on the region. On the other hand, ?SSTmax is up to 4°C in BSouth associated with deeper D26 of >= 100m allowing only warm water (Temp>26) to be brought to the surface.

  15. The Parameterization of PBL height with Helicity and preliminary Application in Tropical Cyclone Prediction

    NASA Astrophysics Data System (ADS)

    Ma, Leiming

    2015-04-01

    Planetary Boundary Layer (PBL) plays an important role in transferring the energy and moisture from ocean to tropical cyclone (TC). Thus, the accuracy of PBL parameterization determines the performance of numerical model on TC prediction to a large extent. Among various components of PBL parameterization, the definition on the height of PBL is the first should be concerned, which determines the vertical scale of PBL and the associated processes of turbulence in different scales. However, up to now, there is lacked consensus on how to define the height of PBL in the TC research community. The PBL heights represented by current numerical models usually exhibits significant difference with TC observation (e.g., Zhang et al., 2011; Storm et al., 2008), leading to the rapid growth of error in TC prediction. In an effort to narrow the gap between PBL parameterization and reality, this study presents a new parameterization scheme for the definition of PBL height. Instead of using traditional definition for PBL height with Richardson number, which has been verified not appropriate for the strongly sheared structure of TC PBL in recent observation studies, the new scheme employs a dynamical definition based on the conception of helicity. In this sense the spiral structures associated with inflow layer and rolls are expected to be represented in PBL parameterization. By defining the PBL height at each grid point, the new scheme also avoids to assume the symmetric inflow layer that is usually implemented in observational studies. The new scheme is applied to the Yonsei University (YSU) scheme in the Weather Research and Forecasting (WRF) model of US National Center for Atmospheric Research (NCAR) and verified with numerical experiments on TC Morakot (2009), which brought torrential rainfall and disaster to Taiwan and China mainland during landfall. The Morakot case is selected in this study to examine the performance of the new scheme in representing various structures of PBL over land and ocean. The results of simulations show that, in addition to enhancing the PBL height in the situation of intensive convection, the new scheme also significantly reduces the PBL height and 2m-temperature over land during the night time, a well-known problem for YSU scheme according to previous studies. The activity of PBL processes are modulated due to the improved PBL height, which ultimately leads to the improvement of prediction on TC Morakot. Key Words: PBL; Parameterization; Numerical Prediction; Tropical Cyclone Acknowledgements. This study was jointly supported by the Chinese National 973 Project (No. 2013CB430300, and No. 2009CB421500) and grant from the National Natural Science Foundation (No. 41475059). References Zhang, J. A., R. F. Rogers, D. S. Nolan, and F. D. Marks Jr., 2011: On the characteristic height scales of the hurricane boundary layer, Mon. Weather Rev., 139, 2523-2535. Storm B., J. Dudhia, S. Basu, et al., 2008: Evaluation of the Weather Research and Forecasting Model on forecasting Low-level Jets: Implications for Wind Energy. Wind Energ., DOI: 10.1002/we.

  16. Tracking a tropical cyclone with ERS-SCAT: a CMOD4 model review

    NASA Astrophysics Data System (ADS)

    de Chiara, Giovanna; Crapolicchio, Raffaele; Migliaccio, Maurizio; Lecomte, Pascal

    2003-02-01

    The spaceborne scatterometer is a microwave radar that provides high precision radiometric measures of the normalized radar cross section ?0 of the ocean surface. The backscatter is affected by the superficial roughness that is in turn related to the local wind. Since microwave wavelengths are used the scatterometer, at first order, can be meant as an instrument which provides measurements independent of clouds and sun illumination therefore it is able to observe the internal structure of a Tropical Cyclone (TC). The relationship between the ?0 and the surface wind filed is described by a geophysical model function (GMF). The model used in the ERS scatterometer processing is the well-known semi-empirical model CMOD4. Unfortunately this model is not tailored for high wind speeds, such as the case of TCs. This fact causes a poor quality in the wind field estimated through the scatterometer data acquired over a TC. In this paper we describe a study in view of a possible extension of the CMOD4 for high wind speeds. The study has been based on the ERS-2 ?0 measurements relevant to six selected TCs and the corresponding wind speeds obtained by employing the Holland model. We have selected six TCs and for each one we have developed a 3D wind speed pattern making use of the wind speed available through the NHC (National Hurricane Center) warnings. The obtained wind speeds are then correlated to the ?0"s acquired over these six TCs. The results obtained in this work support the need to extend the CMOD4 model.

  17. Characterization of surface wind and stress in tropical cyclone with scatterometer

    NASA Astrophysics Data System (ADS)

    Liu, W. T.; Tang, W.; Xie, X.

    2014-12-01

    Wind is air in motion and stress is the momentum exchange between ocean and atmosphere. While the strong wind of a tropical cyclone (TC) causes destruction at landfall, it is the surface stress that drags down the TC. The relations that were established to retrieve moderate wind speeds from the normalized radar cross-section, or backscatter power, measured by Ku-band and C-band scatterometers do not apply well to TC-scale winds. It has been difficult to establish new relations at strong winds because credible strong winds coincident with scatterometer measurements are not sufficient. We will give credence to our hypothesis that there is no distinct physics of radar backscatter from ocean surface for weather phenomenon like the TC. The relation between backscatter and surface roughness or stress does not change under TC, and the same retrieval algorithm can be extended to the TC. The need for changes in wind retrieval algorithm is explained through the change of the drag coefficient that relates wind to stress in TC. We aspire to separate the sensor parameters that affect backscatter, such as, incident angle, azimuth angle, polarization and backscatter frequencies, from the secondary factors related to the physics of the air-sea interface and turbulent transport, such as air stability (shear and buoyance), air density, sea states, and sea sprays, so that we can establish a simple approximation of surface stress from the backscatter averaged over the relevant spatial and temporal scales. We established a relation between backscatter and surface stress over a moderate range of wind speed, where wind measurements coincident with satellite observations are abundant, and the drag coefficient is well established to convert wind measurements to stress. This relation is applied to retrieve stress from the scatterometer measurement in the high wind range of TC. The characteristic of the drag coefficient in TC-scale winds will be discussed. The difference between wind and stress in a TC will be demonstrated.

  18. Dynamical downscaling forecasts of Western North Pacific tropical cyclone genesis and landfall

    NASA Astrophysics Data System (ADS)

    Huang, Wan-Ru; Chan, Johnny C. L.

    2014-04-01

    This study evaluates the potential use of the regional climate model version 3 (RegCM3) driven by (1) the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) data during 1982-2001 and (2) the NCEP Climate Forecast System Version 2 (CFS2) hindcast data during 2000-2010 in forecasting Western North Pacific (WNP) tropical cyclone (TC) activity. The first experiment is conducted to investigate the ability of the model in generating a good climatology of TC activity in spatial and temporal scales, so the model could be used in the second experiment to test its ability in forecasting TC genesis and landfall. Both experiments extend through the May to October WNP-TC season. Results show that the use of RegCM3 driven by the CFSR achieves a better simulation on the temporal and spatial variation of WNP-TC genesis during 1982-2001, as compared to previous studies using the same model but driven by the ERA40 reanalysis. In addition, diagnoses on the use of RegCM3 driven by the CFS2 point out that the 2000-2010 WNP-TC genesis locations and numbers from the model are very similar to those from the observations. The skill of RegCM3 in the forecasts of landfalling TCs is higher over the Southeast Asian region than over the other sub-regions of East Asia. Potential causes for such regional differences are discussed. Most importantly, statistical analyses show that the use of RegCM3 driven by the CFS2 gives a better forecast skill than the use of CFS2 alone for the prediction of WNP-TCs making landfall in East Asia. This indicates that the use of a dynamical downscaling method for the global forecast data would likely lead to a higher forecast skill of regional TC landfalls in most of the East Asian region.

  19. The performance of the new tropical cyclone track prediction system of the China National Meteorological Center

    NASA Astrophysics Data System (ADS)

    Ryder Wilkie, Kari T.; Mertl, Amy L.; Traniello, James F. A.

    2007-08-01

    The global spectral model (GSM) at T213 horizontal resolution with 31 vertical levels has been used operationally in the China National Meteorological Center (CNMC) since 2002. The results show that the GSM is skillful in predicting large-scale circulations because of both the high spatial resolution and the improved model physics. However, because of the low skill in predicting the tropical cyclone (TC) genesis, the model has low skill in predicting TC tracks. In order to improve the prediction skill for TC tracks, an asymmetric bogus vortex scheme was implemented in the CNMCs operational GSM, and has being run in an experimental mode in 2003 and in an operational mode since 2004. In this paper, the performance of the new system in predicting TC tracks over the western North Pacific in the last 3 years are evaluated together with a description of the construction of the asymmetric vortex bogus scheme and its implementation into the CNMCs GSM. It is shown that the asymmetric bogus vortex scheme can improve the track forecast skill not only in short term but also beyond 72 h compared with the corresponding axisymmetric vortex bogus scheme. The results also show that the performance of the GSM with the asymmetric vortex bogus scheme is superior to that of the current operational limited area TC model used at CNMC. However, systematic errors are found in the new TC prediction system: the model predicted tracks tend to deflect westward when TCs travel northeastward while northward when TCs travel westward or northwestward. The plan for future improvement and development of the TC prediction system at CNMC is also briefly discussed.

  20. Remote sensing of the ocean and the atmospheric boundary layer within tropical cyclones

    NASA Astrophysics Data System (ADS)

    Esteban Fernandez, Daniel

    This dissertation presents the Imaging Wind and Rain Airborne Profiler (IWRAP), the first high-resolution dual-band airborne Doppler radar designed to study the inner core of Tropical Cyclones (TCs). IWRAP is usually operated from a National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft during missions through TCs and severe ocean storms. The system is designed to provide high-resolution dual-polarized C- and Ku-band reflectivity and Doppler velocity profiles of the atmospheric boundary layer (ABL) within the inner core precipitation bands of TCs and to study the effects precipitation has on ocean wind scatterometry as it applies to TCs. A summary of the principles of operation and the design of the instrument is given, with an emphasis on the unique digital receiver. Airborne ocean backscatter measurements at C- and Ku-band wavelengths and HH and VV polarizations obtained in moderate to very high wind speed conditions (25--65 m·s-1) are presented. The differences between these measurements and current geophysical model functions (GMFs) are reported. The impact of these results on satellite-based scatterometry is discussed, and their application is illustrated through the reprocessing of QuikSCAT passes with the new GMFs. The use of dual wavelength techniques to determine differential attenuation from IWRAP's dual band reflectivity measurements, as well as to derive rainfall rates and drop-size distribution parameters is also addressed. In addition, results on the use of the radar Doppler velocity measurements to derive the three-dimensional (north, east and vertical) components of the ABL winds within rainbands of TCs are presented. Validation of these results is performed by comparison against other available datasets. IWRAP's unique imaging capability provides, to our knowledge, the highest-resolution measurements of the ABL winds of a hurricane ever obtained.

  1. Shallow ocean response to tropical cyclones observed on the continental shelf of the northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Yang, Bing; Hou, Yijun; Hu, Po; Liu, Ze; Liu, Yahao

    2015-05-01

    Based on observed temperature and velocity in 2005 in northwestern South China Sea, the shallow ocean responses to three tropical cyclones were examined. The oceanic response to Washi was similar to common observations with 2°C cooling of the ocean surface and slight warming of the thermocline resulted from vertical entrainment. Moreover, the wavefield was dominated by first mode near-inertial oscillations, which were red-shifted and trapped by negative background vorticity leading to an e-folding timescale of 12 days. The repeated reflections by the surface and bottom boundaries were thought to yield the successive emergence of higher modes. The oceanic responses to Vicente appeared to be insignificant with cooling of the ocean surface by only 0.5°C and near-inertial currents no larger than 0.10 m/s as a result of a deepened surface mixed layer. However, the oceanic responses to Typhoon Damrey were drastic with cooling of 4.5°C near the surface and successive barotropic-like near-inertial oscillations. During the forced stage, the upper ocean heat content decreased conspicuously by 11.65% and the stratification was thoroughly destroyed by vertical mixing. In the relaxation stage, the water particle had vertical displacement of 20-30 m generated by inertial pumping. The current response to Damrey was weaker than Washi due to the deepened mixed layer and the destroyed stratification. Our results suggested that the shallow water oceanic responses to tropical cyclones varied significantly with the intensity of tropical cyclones, and was affected by local stratification and background vorticity.

  2. Global warming and tropical cyclone climate in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Kang, Nam-Young

    Violent tropical cyclones (TCs) continue to inflict serious impacts on national economies and welfare, but how they are responding to global warming has not been fully clarified. Here I construct an empirical framework that shows the observations supporting a strong link between rising global ocean warmth and increasing trade-off between TC intensity and frequency in the western North Pacific. Thermodynamic structure of the tropical western North Pacific with high global ocean warmth is characterized by convectively more unstable lower troposphere with greater heat and moisture, but this instability is simultaneously accompanied by anomalous high pressure in the middle and upper troposphere over the same region. Increasing trade-off level between TC intensity and frequency in a warmer year proves that this environment further inhibits the TC occurrences over the region, but TCs that form tend to discharge stored energy to upper troposphere with stronger intensities. By increasing the intensity threshold at higher levels we confirmed that the TC climate connection with global ocean warmth occurs throughout the strongest portion of TCs, and the environmental connection of the TC climate is more conspicuous in the extreme portion of TCs. Intensities at the strongest 10~% of the western North Pacific TCs are comparable to super typhoons on average, the increasing trade-off magnitude clearly suggests that super typhoons in a warmer year gets stronger. Conclusively, the negative collinear feature of the thermodynamics influences the portion of TCs at the highest intensities, and super typhoons are likely to become stronger at the expense of overall TC frequencies in a warmer world. The consequence of this finding is that record-breaking TC intensities occur at the expense of overall TC frequencies under global warming. TC activity is understood as a variation which is independent of global warming, and could be assumed to be an internal variability having no trend. Frequency variation and super typhoon intensity variation are regarded as the addition of global warming influence on TC activity variation. The structure depicts how a previous intensity record is overtaken and frequency falls continuously in the global warming environment in a linear perspective. A peak TC activity year when global ocean warmth is the highest ever is likely to experience a record-breaking intensity. In the same way, the least number of annual TCs may appear when a lull of TC activity occurs in the warmest year.

  3. Improvements to Stepped Frequency Microwave Radiometer Real-time Tropical Cyclone Products

    NASA Astrophysics Data System (ADS)

    Uhlhorn, E. W.; Klotz, B.

    2012-12-01

    With the installation of C-band stepped frequency microwave radiometers (SFMR) on Air Force Reserve Command WC-130J hurricane reconnaissance aircraft, the SFMR has assumed a prominent role for operational measurement of surface winds, and thus, hurricane intensity estimation. The current SFMR wind retrieval algorithm was developed from GPS dropwindsonde surface wind measurements, and has been successfully implemented across all SFMR-equipped aircraft. The algorithm improvements were specifically targeted at improving surface wind accuracy at hurricane force conditions (> 65 kts, 33 m/s), especially within the eyewall, although the SFMR surface wind vs. emissivity geophysical model function was developed over a broad range of wind speeds (10-140 kts, 5-70 m/s) with the expectation that the hurricane wind field could be readily measured in general. Due to the significant microwave absorption by precipitation, a by-product of the wind retrieval process is an estimate of the path-averaged rain rate (in actuality, the rain water content). An SFMR surface wind speed high bias in strong precipitation has recently been quantified and is particularly evident at weak-to-moderate wind speeds (<65 kts, 33 m/s) and large rain rates (>20 mm/hr), which has important implications for identifying tropical systems at the depression and storm stages, and additionally for observing significant outer wind radii. A major reason for this wind bias is due to an inaccurate rain absorption model that was used to develop the current surface emissivity vs. wind speed geophysical model function. Observations now suggest that the rain-induced absorption is significantly overestimated by the model, resulting in underestimated rain rate values. With the wind speed bias identified, the rain absorption component of the SFMR geophysical model function is addressed to provide an improved rain rate product. This new absorption model is developed by relating SFMR excess brightness temperature observations to external precipitation information including from WP-3D Droplet Measurement Technologies Precipitation Imaging Probe and airborne tail Doppler (X-band) and lower fuselage (C-band) radar data. Peak rain rate values using this updated model function are typically ~80 mm/hr, which is somewhat higher than maximum values found using the previous model version. This rain rate value equates to a radar reflectivity of ~50 dBZ, consistent with the maximum reflectivity values typically found in tropical cyclones.

  4. The environments and associated physical mechanisms that cause size and structure changes in a tropical cyclone

    NASA Astrophysics Data System (ADS)

    Stovern, Diana

    Tropical cyclones (TCs) can make significant size changes during their lifetime and the amount of size change depends on the environmental conditions surrounding the TC and internal TC dynamics. Focusing on the former, this study explores the impacts that environmental temperature and air-sea temperature difference has on TC size and structure changes. The study is conducted in two parts: the first part uses the WRF-ARW model to test the sensitivity of TC size changes to simple changes in the environment; the second part validates the results from the first part by characterizing the environments associated with real cases of TC size change in the North Atlantic basin. It is found that when the simulated atmosphere is cooled, the initial specific humidity and convective available potential energy (CAPE) decrease but the surface energy fluxes from the ocean increase. The higher surface fluxes support a larger inner- and outer-core precipitation field, which leads to a larger wind field through the diabatic production of potential vorticity. In contrast, a warmer atmosphere with reduced surface energy fluxes inhibits the growth of the TC wind field. The higher initial CAPE and moisture content, however, allow the TC to spin up more rapidly with a compact core of intense precipitation. Thus, it is not the temperature of the atmosphere that is causing the size changes, but instead it is the higher surface energy fluxes that arise from the increased air-sea temperature difference. In the second part of the study, the environments associated with real cases of TC size change in the North Atlantic Basin were characterized. Environmental composites, created using the ERA-Interim reanalysis dataset, show that TCs that made size changes in the deep tropics were typically associated with more environmental, mid-level humidity and higher air-sea temperature difference. The TCs that made large size changes in the extratropics were associated with highly-baroclinic environments and high mid-level moisture south of the TC-circulation center. The results are generally consistent with the size change environments simulated in the first part of this study and with others that have modeled the impact of environmental moisture on TC size changes.

  5. Cloud-to-Ground Lightning Characteristics of a Major Tropical Cyclone Tornado Outbreak

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Goodman, Steven J.

    1999-01-01

    It is well known that most tropical cyclones (TCs) that make landfall along the Gulf coast of the United States spawn at least a few tornadoes. Although most landfalling TCs generate fewer than a dozen such tornadoes, a small proportion produce large swarm outbreaks, with as many as 25 or more tornadoes. Usually, these major outbreaks occur in large, intense hurricane-strength TCs, but on 15-17 August 1994 Tropical Storm Beryl spun off 37 tornadoes along its path from the Florida panhandle through the mid-Atlantic states. Some 32 of these tornadoes occurred on 16 August 1994 from eastern Georgia to southern Virginia, with most of these taking place in South Carolina. Beryl's 37 tornadoes moved it into what was at that time fifth place historically in terms of TC tornado productivity. The Beryl outbreak is especially noteworthy in that at least three of the tornadoes achieved peak intensity of F3 on the Fujita damage intensity scale. Although no fatalities resulted from the Beryl outbreak, at least 50 persons suffered injuries, and property damages totalled more than $50 million . The Beryl outbreak is a good example of a TC whose greatest danger to the public is its post-landfall severe weather. In this respect, and in the character of its swarm outbreak of tornadoes, it resembles another large tornado outbreak spawned by a relatively weak TC, Hurricane Danny of 1985). In the Danny outbreak, numerous shallow mini-supercell storms were found to have occurred, and it was noted that, because of the storms' relatively shallow depth, cloud-to-ground (CG) lightning was negligible. Better observations of future TC tornado outbreaks, especially with modern surveillance tools such as Doppler radars and the National Lightning Detection Network (NLDN), were recommended. Although the Beryl tornado outbreak is not the first set of TC-spawned tornado storms to be observed with the NLDN, it is one of the largest and likely the most intense such outbreak. The purpose of this paper is to document the NLDN-derived CG lightning characteristics of Beryl's tornadic storms, and to see how they compare with observations of CG lightning activity in other types of severe storms. In particular, we attempt to quantify the CG flash rates of TC tornadic cells, and to discover if there are any characteristics of their CG activity that may be useful to operational forecasters seeking to distinguish which cells are most likely to produce severe weather.

  6. Cross-equatorial influences of a South American cold surge on the development of two eastern North Pacific tropical cyclones 

    E-print Network

    Millier, Vicki Anne

    1989-01-01

    case study of such an event. In late May 1979 a severe cold front passed over South America. On the mornings of 31 May and 1 June I'our states in Brazil experienced the worst freeze since 1975. Simultaneously, two tropical cyclones developed oif... Brazil and was the worst cold surge experienced in Brazil since 1975. ' Fortune and Kousky (1983) studied this cold front (Fig. 2) and found that the strong cold surge was the result of the superposition of a shortwave trough on a longwave trough...

  7. Global Ensemble Predictions of 2009's Tropical Cyclones Initialized with an Ensemble Kalman Filter

    E-print Network

    Hamill, Tom

    cyclone central pressure and position produced at the National Hurricane Center and the Joint Typhoon­EnKF initialized relatively deep vortices by assimilating the TC central pressure estimate, the model storms filled

  8. Cyclone Susan

    NSDL National Science Digital Library

    Greg Shirah

    1999-01-21

    The Tropical Rainfall Measuring Mission (TRMM) satellite was launched in November 1997. An early TRMM observation was Cyclone Susan, which barreled through the South Pacific Ocean in the second week of January 1998. TRMM measured the storms rain height and coverage.

  9. A Statistical Model of Tropical Cyclone Tracks in the Western North Pacific with ENSO-Dependent Cyclogenesis

    NASA Technical Reports Server (NTRS)

    Yonekura, Emmi; Hall, Timothy M.

    2011-01-01

    A new statistical model for western North Pacific Ocean tropical cyclone genesis and tracks is developed and applied to estimate regionally resolved tropical cyclone landfall rates along the coasts of the Asian mainland, Japan, and the Philippines. The model is constructed on International Best Track Archive for Climate Stewardship (IBTrACS) 1945-2007 historical data for the western North Pacific. The model is evaluated in several ways, including comparing the stochastic spread in simulated landfall rates with historic landfall rates. Although certain biases have been detected, overall the model performs well on the diagnostic tests, for example, reproducing well the geographic distribution of landfall rates. Western North Pacific cyclogenesis is influenced by El Nino-Southern Oscillation (ENSO). This dependence is incorporated in the model s genesis component to project the ENSO-genesis dependence onto landfall rates. There is a pronounced shift southeastward in cyclogenesis and a small but significant reduction in basinwide annual counts with increasing ENSO index value. On almost all regions of coast, landfall rates are significantly higher in a negative ENSO state (La Nina).

  10. GPS monitoring of the thropospheric water vapor fields due to "Vince" tropical cyclone in October 2005 (South Iberian Peninsula)

    NASA Astrophysics Data System (ADS)

    Seco, A.; Ramirez, F.; Gonzalez, P. J.; García, R.; Yagüe, C.; Miqueleiz, L.; Fernández, J.

    2009-04-01

    We present the GPS estimated water vapor content, distribution and temporal variation due to the "Vince" tropical cyclone on October 11th, 2005 in its track over the Southern part of the Iberian Peninsula. The anomalous event (Vince is the only "historical" tropical cyclone that arrived the Iberian Peninsula) was studied using a sparse array of GPS stations throughout South Portugal and Spain. Analysis of GPS data recorded significant increases of Zenith Tropospheric Delay (ZTD), Zenith Wet Delay (ZTD) and precipitable water (PW). These increments were observed in all the GPS stations along October 11th, corresponding with the West-to-East observed track of Vince. Unusual values of ZTD, ZWD and PW was decreasing gradually from the western stations to the eastern stations. This observation correlates well with the Vince's weakening, due to lack of water vapor inputs (Atlantic ocean) and its intrusion into the continental area (Southern Iberian). Furthermore, good correlation has been observed between PW values and torrential rainfalls registered at rain gauges from the available meteorological networks.

  11. Measurements of the upper troposphere and lower stratosphere during tropical cyclones using the GPS radio occultation technique

    NASA Astrophysics Data System (ADS)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig; Nielsen, Johannes

    2011-01-01

    Water vapour transport to the upper troposphere and lower stratosphere by deep convective storms affects the radiation balance of the atmosphere and has been proposed as an important component of climate change. The aim of the work presented here is to understand if the GPS radio occultation technique is useful for characterization of this process. Our assessment addresses the question if severe storms leave a significant signature in radio occultation profiles in the upper troposphere/lower stratosphere. Radio occultation data from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) were analyzed, focusing on two particular tropical cyclones with completely different characteristics, the hurricane Bertha, which formed in the Atlantic Basin during July 2008 and reached a maximum intensity of Category 3, and the typhoon Hondo, which formed in the south Indian Ocean during 2008 reaching a maximum intensity of Category 4. The result is positive, suggesting that the bending angle of a GPS radio occultation signal contains interesting information on the atmosphere around the tropopause, but not any information regarding the water vapour. The maximum percentage anomaly of bending angle between 14 and 18 km of altitude during tropical cyclones is typically larger than the annual mean by 5-15% and it can reach 20% for extreme cases. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  12. Dynamic impact of the vertical shear of gradient wind on the tropical cyclone boundary layer wind field

    NASA Astrophysics Data System (ADS)

    Cai, Ninghao; Xu, Xin; Song, Lili; Bai, Lina; Ming, Jie; Wang, Yuan

    2014-02-01

    This work studies the impact of the vertical shear of gradient wind (VSGW) in the free atmosphere on the tropical cyclone boundary layer (TCBL). A new TCBL model is established, which relies on fiveforce balance including the pressure gradient force, Coriolis force, centrifugal force, turbulent friction, and inertial deviation force. This model is then employed to idealize tropical cyclones (TCs) produced by DeMaria's model, under different VSGW conditions (non-VSGW, positive VSGW, negative VSGW, and VSGW increase/decrease along the radial direction). The results show that the free-atmosphere VSGW is particularly important to the intensity of TC. For negative VSGW, the total horizontal velocity in the TCBL is somewhat suppressed. However, with the maximum radial inflow displaced upward and outward, the radial velocity notably intensifies. Consequently, the convergence is enhanced throughout the TCBL, giving rise to a stronger vertical pumping at the TCBL top. In contrast, for positive VSGW, the radial inflow is significantly suppressed, even with divergent outflow in the middle-upper TCBL. For varying VSGW along the radial direction, the results indicate that the sign and value of VSGW is more important than its radial distribution, and the negative VSGW induces stronger convergence and Ekman pumping in the TCBL, which favors the formation and intensification of TC.

  13. Modification of the ionosphere near the terminator due to the passage of a strong tropical cyclone through the large Island

    NASA Astrophysics Data System (ADS)

    Belyaev, G.; Boychev, B.; Kostin, V.; Trushkina, E.; Ovcharenko, O.

    2015-03-01

    Earlier by the authors according to the Intercosmos Bulgaria-1300 and Cosmos-1809 satellite data it's been shown that the ionosphere is modified above the tropical cyclones (TC). Local perturbations of the plasma density, the appearance of the electric fields and the development of ELF-VLF zone of turbulence were observed. These effects were due to the injection of up stream of neutral particles from TC. In this paper the data of the Cosmos-1809 satellite when tropical cyclone Harry (1989) passed through the island of New Caledonia was examined. Influence of evening and morning terminators on the structure of the ionosphere from TC was discussed. It is detected: 1 - the appearance of latitude belt (up to 5000km) of structured perturbations in the night ionosphere; 2 - simulation in the illuminated ionosphere of periodic oscillation of the electric field with a scale ~ 400 km, passing beyond plasma pause. Model for the formation above TC in the lower ionosphere vertical submerged jet that injects neutral particles of different varieties into the upper ionosphere on ballistic trajectories was proposed. Changing of the ionization of neutral particles near the terminator and the deviation of the jet under the interaction of the TC with the island are confirmed in the proposed model.

  14. Uncertainty quantification for a climatology of the frequency and spatial distribution of North Atlantic tropical cyclone landfalls

    NASA Astrophysics Data System (ADS)

    Tolwinski-Ward, S. E.

    2015-03-01

    A spatially resolved climatology for the annual frequency of tropical cyclone (TC) landfalls along the Atlantic coast of North America is developed, and its uncertainty deriving from multiple sources is quantified. Historical landfall counts in piecewise-linear segments approximating the coastline are modeled using Poisson regression with spatial random effects. Predictors include index representations of the mean hurricane-season phases of the Southern Oscillation, the Atlantic Multidecadal Oscillation, and the North Atlantic Oscillation, with the effect of the latter also modeled spatially. This spatial generalized linear model for landfall frequency is used in conjunction with a data level accounting explicitly for the time-dependent uncertainty in the recorded landfall positions. The model performs skillfully in cross-validation exercises. The inferred effects of the climatic predictors are also consistent with current scientific understanding of the mechanisms through which related large-scale climatic variability affects the development and motion of Atlantic tropical cyclones. Sampling variability in the data over the short length of the observational record and observational error in the historical data are found to contribute substantially to the overall climatological uncertainty. The contribution from uncertainty in the underlying model parameters is negligible compared to these other sources. The model presented here could be used for applications in insurance and risk management, and adaptations could also be used to investigate changes in TC landfall climatology under an uncertain and changing climate.

  15. Potential indirect effects of aerosol on tropical cyclone intensity: convective fluxes and cold-pool activity

    NASA Astrophysics Data System (ADS)

    Krall, G. M.; Cottom, W. R.

    2012-01-01

    Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin-emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentrations. A clean maritime field of cloud condensation nuclei (CCN) was prescribed as marine background CCN concentrations and then based on satellite and global aerosol model output, increased to pollution levels and further enhanced in sensitivity tests. The typhoon was simulated for 96 h beginning 17 August 2008. During the final 60 h CCN concentrations were enhanced as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from the 2008 T-PARC observational campaign using an objective analysis routine. At 36 h, the internal nudging of the model was switched off and allowed to freely evolve on its own. As the typhoon encountered the elevated CCN in the sensitivity tests, a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior was simulated. Early during the ingestion of enhanced CCN, precipitation was reduced due to suppressed collision and coalescence, and storm winds increased in strength. Subsequently, owing to reduced fall speeds of the smaller drops, greater amounts of condensate were thrust into supercooled levels where the drops froze releasing greater amounts of latent heat of freezing. Convection thereby intensified which resulted in enhanced rainfall and more vigorous convectively-produced downdrafts. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools. The enhanced cold-pools blocked the inflow of warm, moist air into the core of the typhoon which led to a weakening of the typhoon with significantly reduced low level wind speeds. The very high amounts of pollution aerosols resulted in large amounts of condensate being thrust into the storm anvil which weakened convective downdrafts and cold-pools, yet the system did show reductions in windspeed (although weaker) compared with the clean control run. This study suggests that ingestion of elevated amounts of CCN into a tropical cyclone (TC) can appreciably alter the intensity of the storm. This implies that intensity prediction of TCs would be improved by including indirect aerosol affects. However, the pollution aerosols have very little impact on the storm track.

  16. Determining relevant parameters for a statistical tropical cyclone genesis tool based upon global model output

    NASA Astrophysics Data System (ADS)

    Halperin, D.; Hart, R. E.; Fuelberg, H. E.; Cossuth, J.

    2013-12-01

    Predicting tropical cyclone (TC) genesis has been a vexing problem for forecasters. While the literature describes environmental conditions which are necessary for TC genesis, predicting if and when a specific disturbance will organize and become a TC remains a challenge. As recently as 5-10 years ago, global models possessed little if any skill in forecasting TC genesis. However, due to increased resolution and more advanced model parameterizations, we have reached the point where global models can provide useful TC genesis guidance to operational forecasters. A recent study evaluated five global models' ability to predict TC genesis out to four days over the North Atlantic basin (Halperin et al. 2013). The results indicate that the models are indeed able to capture the genesis time and location correctly a fair percentage of the time. The study also uncovered model biases. For example, probability of detection and false alarm rate varies spatially within the basin. Also, as expected, the models' performance decreases with increasing lead time. In order to explain these and other biases, it is useful to analyze the model-indicated genesis events further to determine whether or not there are systematic differences between successful forecasts (hits), false alarms, and miss events. This study will examine composites of a number of physically-relevant environmental parameters (e.g., magnitude of vertical wind shear, aerially averaged mid-level relative humidity) and disturbance-based parameters (e.g., 925 hPa maximum wind speed, vertical alignment of relative vorticity) among each TC genesis event classification (i.e., hit, false alarm, miss). We will use standard statistical tests (e.g., Student's t test, Mann-Whitney-U Test) to calculate whether or not any differences are statistically significant. We also plan to discuss how these composite results apply to a few illustrative case studies. The results may help determine which aspects of the forecast are (in)correct and whether the incorrect aspects can be bias-corrected. This, in turn, may allow us to further enhance probabilistic forecasts of TC genesis.

  17. Simple kinematic models for the environmental interaction of tropical cyclones in vertical wind shear

    NASA Astrophysics Data System (ADS)

    Riemer, M.; Montgomery, M. T.

    2011-09-01

    A major impediment to the intensity forecast of tropical cyclones (TCs) is believed to be associated with the interaction of TCs with dry environmental air. However, the conditions under which pronounced TC-environment interaction takes place are not well understood. As a step towards improving our understanding of this problem, we analyze here the flow topology of a TC immersed in an environment of vertical wind shear in an idealized, three-dimensional, convection-permitting numerical experiment. A set of distinct streamlines, the so-called manifolds, can be identified under the assumptions of steady and layer-wise horizontal flow. The manifolds are shown to divide the flow around the TC into distinct regions. The manifold structure in our numerical experiment is more complex than the well-known manifold structure of a non-divergent point vortex in uniform background flow. In particular, one manifold spirals inwards and ends in a limit cycle, a meso-scale dividing streamline encompassing the eyewall above the layer of strong inflow associated with surface friction and below the outflow layer in the upper troposphere. From the perspective of a steady and layer-wise horizontal flow model, the eyewall is well protected from the intrusion of environmental air. In order for the environmental air to intrude into the inner-core convection, time-dependent and/or vertical motions, which are prevalent in the TC inner-core, are necessary. Air with the highest values of moist-entropy resides within the limit cycle. This "moist envelope" is distorted considerably by the imposed vertical wind shear, and the shape of the moist envelope is closely related to the shape of the limit cycle. In a first approximation, the distribution of high- and low-?e air around the TC at low to mid-levels is governed by the stirring of convectively modified air by the steady, horizontal flow. Motivated by the results from the idealized numerical experiment, an analogue model based on a weakly divergent point vortex in background flow is formulated. The simple kinematic model captures the essence of many salient features of the manifold structure in the numerical experiment. A regime diagram representing realistic values of TC intensity and vertical wind shear can be constructed for the point-vortex model. The results indicate distinct scenarios of environmental interaction depending on the ratio of storm intensity and vertical-shear magnitude. Further implications of the new results derived from the manifold analysis for TCs in the real atmosphere are discussed.

  18. Physically-based Assessment of Tropical Cyclone Damage and Economic Losses

    NASA Astrophysics Data System (ADS)

    Lin, N.

    2012-12-01

    Estimating damage and economic losses caused by tropical cyclones (TC) is a topic of considerable research interest in many scientific fields, including meteorology, structural and coastal engineering, and actuarial sciences. One approach is based on the empirical relationship between TC characteristics and loss data. Another is to model the physical mechanism of TC-induced damage. In this talk we discuss about the physically-based approach to predict TC damage and losses due to extreme wind and storm surge. We first present an integrated vulnerability model, which, for the first time, explicitly models the essential mechanisms causing wind damage to residential areas during storm passage, including windborne-debris impact and the pressure-debris interaction that may lead, in a chain reaction, to structural failures (Lin and Vanmarcke 2010; Lin et al. 2010a). This model can be used to predict the economic losses in a residential neighborhood (with hundreds of buildings) during a specific TC (Yau et al. 2011) or applied jointly with a TC risk model (e.g., Emanuel et al 2008) to estimate the expected losses over long time periods. Then we present a TC storm surge risk model that has been applied to New York City (Lin et al. 2010b; Lin et al. 2012; Aerts et al. 2012), Miami-Dade County, Florida (Klima et al. 2011), Galveston, Texas (Lickley, 2012), and other coastal areas around the world (e.g., Tampa, Florida; Persian Gulf; Darwin, Australia; Shanghai, China). These physically-based models are applicable to various coastal areas and have the capability to account for the change of the climate and coastal exposure over time. We also point out that, although made computationally efficient for risk assessment, these models are not suitable for regional or global analysis, which has been a focus of the empirically-based economic analysis (e.g., Hsiang and Narita 2012). A future research direction is to simplify the physically-based models, possibly through parameterization, and make connections to the global loss data and economic analysis.

  19. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS08) field experiment - Part 1: The role of the easterly wave critical layer

    Microsoft Academic Search

    M. T. Montgomery; L. L. Lussier III; R. W. Moore; Z. Wang

    2009-01-01

    An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the surrounding base state flow was an easterly trade wind flow and the precursor disturbance to Typhoon Nuri was an easterly wave that originated

  20. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS08) field experiment - Part 1: The role of the easterly wave critical layer

    Microsoft Academic Search

    M. T. Montgomery; L. L. Lussier III; R. W. Moore; Z. Wang

    2010-01-01

    An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the surrounding base state is an easterly trade wind flow and the precursor disturbance to Typhoon Nuri is an easterly wave that originates in

  1. Studies ofthe influence of rainfall upon scatterometer estimates for sea surface stress: Applications to boundary layer parameterization and drag coefficient models within tropical cyclone environments

    Microsoft Academic Search

    David E. Weissman; Henry R. Winterbottom; Mark A. Bourassa

    2010-01-01

    The use of satellite scatterometers to probe the winds in and near strong tropical cyclones (TCs) is a valuable tool for both numerical weather prediction (NWP) and weather forecasters. The presence of widespread rain in these storms complicates the estimation of surface winds from the satellite. Improvements in the techniques to infer surface winds from the satellite observations, which remove

  2. The influence of rainfall upon Scatterometer estimates for sea surface stress: Applications to boundary layer parameterization and drag coefficient models within tropical cyclone environments

    Microsoft Academic Search

    David E. Weissman; Henry R. Winterbottom; Mark A. Bourassa

    2010-01-01

    The use of satellite scatterometers to probe the winds in and near strong tropical cyclones (TCs) is a valuable tool for both numerical weather prediction (NWP) and weather forecasters. The presence of widespread rain in these storms complicates the estimation of surface winds from the satellite. Improvements in the techniques to infer surface winds from the satellite observations, which remove

  3. Understanding the Role of Cloud and Convective Processes in Simulating the Weaker Tropical Cyclones over Indian Seas

    NASA Astrophysics Data System (ADS)

    Kanase, Radhika D.; Mukhopadhyay, P.; Salvekar, P. S.

    2015-06-01

    This study addresses the problem of incorporating moist processes (resolving the grid scale and parameterizing the subgrid scale) at resolutions of 9 and 3 km with double- and triple-nested domains, respectively, in predicting the track and intensity of four cases of weaker tropical cyclones over the North Indian Ocean. The sensitivity experiments are carried out with three convective parameterization schemes, and the results are evaluated based on the track and intensity of cyclones. The Betts-Miller-Janjic scheme shows the most reasonable representation of track and intensity and therefore is used for all sensitivity experiments related to microphysical schemes in two and three domains. Three sets of microphysics sensitivity experiments are carried out: The first set includes experiments with parameterized moist convection (referred to as the 9-km experiment) in two domains (27 and 9 km). The second and third sets of simulation experiments are carried out at 9 km in two domains (27 and 9 km; referred to as the 9-km-noCP) and at 3 km in three domains (27 km, 9 km and 3 km; referred to as the 3-km experiment), respectively, by resolving the grid-scale convection explicitly with the four bulk microphysical schemes. The explicit moist convection treatment at 9- and 3-km resolution produces a better cyclone simulation than the parameterized convection at 9-km resolution. The latent heat released in the generation of hydrometeors such as snow and graupel in the mid-tropospheric levels appears to influence the heating within the inner core of the cyclone. The comparable and more realistic representation of mid-tropospheric heating is possibly one of the main reasons behind the improvement at 9-km-noCP and 3 km. The stronger vertical advection of moist static energy gives well-organized mesoscale convection within the cyclone environment at 9-km-noCP and 3-km resolution. This study therefore demonstrates the importance of microphysical processes in the simulation of weaker TC over the North Indian Ocean.

  4. The Impact of Spray-Mediated Enhanced Enthalpy and Reduced Drag Coefficients in the Modelling of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Zweers, N. C.; Makin, V. K.; de Vries, J. W.; Kudryavtsev, V. N.

    2015-06-01

    The impact of new parametrizations for drag and air-sea enthalpy exchange on modelling the intensity of tropical cyclones with a numerical weather prediction (NWP) model is examined. These parametrizations follow from a model for the marine atmospheric boundary layer for high wind-speed conditions in the presence of spray droplets that originate from breaking wave crests. This model accounts for the direct impact of these droplets on the air-sea momentum flux through action of a spray force, which originates from the interaction of the `rain' of spray droplets with the vertical wind shear and is expressed in terms of the spray generation function (SGF). The SGF is cubic in the wind speed up to 50 m s beyond which its value increases less strongly. The drag coefficient () decreases from a wind speed of approximately 30 m s, in agreement with the available measurements in these conditions. The enthalpy exchange coefficient () increases with increasing wind speed and slowly decreases beyond a wind speed of about 40 m s due to the strong decrease in . The value for is in agreement with observational data for wind speeds up to 30 m s; for higher wind speeds the value is in the range 1.2-1.5 in agreement with a well-established theory. The parametrization is tested in an NWP model. The tropical cyclones Ivan (2004) and Katrina (2005) in the Gulf of Mexico are simulated. To the sea surface temperatures (SSTs) from the European Centre archive that were prescribed to the NWP model, a parametrized cooling (based on estimations from theoretical studies and measurements) was applied during the model forecasts, as the NWP model does not resolve locally rather strong induced reductions in SSTs. The simulations show that realistic tropical cyclone wind speeds and central pressure can be obtained with the proposed drag and enthalpy parametrizations. The results indicate that the value for at very high wind speeds is in the correct range. Moreover, the results motivate the application of the parametrizations in atmosphere-ocean coupled models.

  5. Ionospheric precursors of the intensification of isolated tropical cyclones according to the IKB-1300 and Cosmos-1809 satellite data

    NASA Astrophysics Data System (ADS)

    Kostin, V. M.; Belyaev, G. G.; Boichev, B.; Trushkina, E. P.; Ovcharenko, O. Ya.

    2015-03-01

    The ionospheric parameters were analyzed, which made it possible to distinguish several successive stages in the development of isolated tropical cyclones (TCs). Data were taken from the Cosmos-1809 and Intercosmos Bulgaria-1300 satellites, which passed over several dozen TCs. The first stage of TC development consists of a sharp increase in altitudinal substorm activity caused by a tropical disturbance and depression. During this stage, plasma density caverns extending over several hundreds of kilometers are observed in the nighttime upper ionosphere a day before the formation of a tropical storm or even a category-I hurricane. The second stage, typical of TCs with intensities reaching categories I and II, is the displacement of a wide plasma density maximum in the upper ionosphere from the geomagnetic equator into the region, the center of which along the geomagnetic field line is projected to 200-230 km altitudes at a TC latitude. The third stage, which is typical of TC categories III-V, consists of the formation of an additional Ne peak (with a width reaching 1000 km) near the TC zenith. This peak includes ? Ne disturbances and is accompanied by electrostatic oscillations at the H+ and He+ cyclotron frequencies and at the lower hybrid resonance frequency and by electric fields that are projected into the magnetically conjugate region. The crossing of New Caledonia by the category-IV TC Harry was considered in detail. It was shown that the neutral particle ascending jet probably deviated along the meridian in this case.

  6. Coupled Atmosphere-Wave-Ocean Modeling of Tropical Cyclones: Progress, Challenges, and Ways Forward

    NASA Astrophysics Data System (ADS)

    Chen, Shuyi

    2015-04-01

    It has long been recognized that air-sea interaction plays an important role in tropical cyclones (TC) intensity change. However, most current numerical weather prediction (NWP) models are deficient in predicting TC intensity. The extreme high winds, intense rainfall, large ocean waves, and copious sea spray in TCs push the surface-exchange parameters for temperature, water vapor, and momentum into untested regimes. Parameterizations of air-sea fluxes in NWP models are often crude and create "manmade" energy source/sink that does not exist, especially in the absence of a fully interactive ocean in the model. The erroneous surface heat, moisture, and momentum fluxes can cause compounding errors in the model (e.g., precipitation, water vapor, boundary layer properties). The energy source (heat and moisture fluxes from the ocean) and sink (surface friction and wind-induced upper ocean cooling) are critical to TC intensity. However, observations of air-sea fluxes in TCs are very limited, especially in extreme high wind conditions underneath of the eyewall region. The Coupled Boundary Layer Air-Sea Transfer (CBLAST) program was designed to better understand the air-sea interaction, especially in high wind conditions, which included laboratory and coupled model experiments and field campaign in 2003-04 hurricane seasons. Significant progress has been made in better understanding of air-sea exchange coefficients up to 30 m/s, i.e., a leveling off in drag coefficient and relatively invariant exchange coefficient of enthalpy with wind speed. More recently, the Impact of Typhoon on the Ocean in the Pacific (ITOP) field campaign in 2010 has provided an unprecedented data set to study the air-sea fluxes in TCs and their impact on TC structure and intensity. More than 800 GPS dropsondes and 900 AXBTs/AXCTs as well as drifters, floats, and moorings were deployed in TCs, including Typhoons Fanapi and Malakas, and Supertyphoon Megi with a record peak wind speed of more than 80 m/s. It is found that the air-sea fluxes are quite asymmetric around a storm with complex features representing various air-sea interaction processes in TCs. A unique observation in Typhoon Fanapi is the development of a stable boundary layer in the near-storm cold wake region, which has a direct impact on TC inner core structure and intensity. Despite of the progress, challenges remain. Air-sea momentum exchange in wind speed greater than 30-40 m/s is largely unresolved. Directional wind-wave stress and wave-current stress are difficult to determine from observations. Effects of sea spray on the air-sea fluxes are still not well understood. This talk will provide an overview on progress made in recent years, challenges we are facing, and ways forward. An integrated coupled observational and atmosphere-wave-ocean modeling system is urgently needed, in which coupled model development and targeted observations from field campaign and lab measurements together form the core of the research and prediction system. Another important aspect is that fully coupled models provide explicit, integrated impact forecasts of wind, rain, waves, ocean currents and surges in TCs and winter storms, which are missing in most current NWP models. It requires a new strategy for model development, evaluation, and verification. Ensemble forecasts using high-resolution coupled atmosphere-wave-ocean models can provide probabilistic forecasts and quantitative uncertainty estimates, which also allow us to explore new methodologies to verify probabilistic impact forecasts and evaluate model physics using a stochastic approach. Examples of such approach in TCs including Superstorm Sandy will be presented.

  7. The potential impacts of warmer-continent-related lower-layer equatorial westerly wind on tropical cyclone initiation

    NASA Astrophysics Data System (ADS)

    Yuan, Zhuojian; Qian, Yu-Kun; Qi, Jindian; Wu, Junjie

    2012-03-01

    Global climate models predict that the increasing Amazonian-deforestation rates cause rising temperatures (increases of 1.8°C to 8°C under different conditions) and Amazonian drying over the 21st century. Observations in the 20th century also show that over the warmer continent and the nearby western South Atlantic Ocean, the lower-layer equatorial westerly wind (LLEWW) strengthens with the initiation of tropical cyclones (TCs). The warmer-continent-related LLEWW can result from the Coriolis-force-induced deflection of the cross-equatorial flow (similar to the well-known heat-island effect on sea breeze) driven by the enhanced land-sea contrast between the warmer urbanized continents and relatively cold oceans. This study focuses on the processes relating the warmer-continent-related LLEWW to the TC initiation and demonstrates that the LLEWW embedded in trade easterlies can directly initiate TCs by creating cyclonic wind shears and forming the intertropical convergence zone. In addition to this direct effect, the LLEWW combined with the rotating Earth can boost additional updraft vapor over the high sea-surface temperature region (factor 1), facilitating a surface-to-midtroposphere moist layer (factor 2) and convective instability (factor 3) followed by diabatic processes. According to previous studies, the diabatic heating in a finite equatorial region also activates TCs (factor 4) on each side of the Equator with weak vertical shear (factor 5). Factors 1-5 are favorable conditions for the initiation of severe TCs. Statistical analyses show that the earliest signal of sustained LLEWW not only leads the earliest signal of sustained tropical depression by >3 days but also explains a higher percentage of total variance.

  8. Tropical Cyclone Reconstruction Implications of Hurricane Irene Precipitation ?18O Anomalies and Their Transfer into Oysters in the Chesapeake Bay Region, August 2011

    NASA Astrophysics Data System (ADS)

    Kilbourne, K. H.; Biasatti, D.; Cooper, L. W.

    2012-12-01

    Improved records of past tropical cyclone frequency, intensity or track location from paleoclimate proxies could further our understanding of the decadal to centennial-scale controls on tropical cyclone activity when paired with independent paleoclimate information. Better understanding of the controls on tropical cyclone activity over these time scales can improve our projections of tropical cyclone activity under future climate scenarios, providing the opportunity to prepare for changes in tropical cyclone frequency, intensity or location. Tropical cyclone rainfall tends to be more depleted in the heavy isotope of oxygen (18O) than typical summertime low- to mid-latitude rainfall, providing a potential signal of tropical cyclone events that may be preserved in coastal biogenic carbonates. Such a paleotempest proxy depends on the transmission of the oxygen isotopic signal from precipitation into the coastal zone and concomitant incorporation into biogenic carbonates. This study quantified the oxygen isotopic signal of precipitation from Hurricane Irene as the signal passed into the Chesapeake Bay estuary and into oysters growing in the estuary. Hurricane Irene swept through the Chesapeake Bay region in August 2011. Meteoric water samples were collected at regular intervals during the storm, to characterize the 18O-depletion of the storm-related precipitation. Immediately following the storm, the oxygen isotopic signal was measured in the main stem of the Chesapeake Bay and in Lesson Cove, a sub-estuary near the Patuxent River mouth. Oysters collected from Lesson Cove shortly after the storm were also analyzed for oxygen isotopes in shell carbonate to determine if oysters could be accurate recorders of past storm events. The storm outer rain bands had ?18O value of -4.1‰, with a -7.5‰ isotopic gradient to the inner rain bands, which had ?18O values averaging -11.6‰ as the storm passed up the Chesapeake Bay. The smaller estuary of Lesson Cove showed little to no isotopic shift within hours of the storm, when the ?18O values were -4.2‰, but isotopic depletion peaked a day later with water ?18O values at -9.6‰, and was followed by a return to near pre-storm values over the course of the following 5 days. The main stem of the Chesapeake had a much smaller ?18O shift associated with the storm, beginning at -4.3‰ with a shift of only -0.3‰ to a minimum of -4.6‰ that returned to pre-storm values over the course of 9 days, illustrating the dominance of ocean oxygen isotopic composition over that of added precipitation in a large estuary. The results of this study suggest that the use of oxygen isotopes in biogenic carbonates for tropical cyclone reconstruction will be more successful in small estuaries where freshwater inputs dominate and dilution by seawater is minimal. These more restricted environments are more likely to show larger and easier to detect tropical cyclone-related isotopic anomalies.

  9. Comparisons and Contrasts Between Mediterranean Flood-Producing Orographic Storms and Tropical Cyclones Modified by Complex Orography

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Tripoli, Gregory J.; Lee, Chun-Woo; Mehta, Amita; Mugnai, Alberto; Panegrossi, Giulia; Sohn, Byung-Ju

    2003-01-01

    Often, late-year, flood-producing storms in the Mediterranean Alps region arise from baroclinic disturbances developing on westerly longwaves, with the incipient storm circulations appearing well west of the flood zone. Regardless of the genesis locations and before the storms begin their flow interactions with the orography of the Mediterranean Alps, a process which can produce intense long-lived rainfall over the mountainous terrain of Italy and France, most of their moisture is drawn from warm Mediterranean waters while important elements of their thermodynamic structure are derived from airmass properties originating in north Africa and the Mediterranean basin itself. In fact, because of strong thermodynamic contrasts between the baroclinic zone producing the incipient disturbance and high potential temperature air from the south advecting into and wrapping around the storm center, a Mediterranean storm whose origins are from an evolving shortwave baroclinic perturbation, can become a quasi-warm core hybrid in term of its energetics composition, a process somewhat akin to the development of polar lows. This process begs the question of whether there are similarities between the autumn-winter season flood producing storms of the Mediterranean Alps and warm core tropical cyclones which become altered dynamically and thermodynamically by landfall over steep orographic terrain. This study investigates, from a comparison and contrast perspective, how the similarities and differences between the two types of storms manifest themselves over their respective life cycles. Before the orographically-induced precipitation-release stage in which both types of storm have evolved to the same hydrometeorlogical conclusion, the two storm categories are transforming from entirely distinctive origins, i.e., the classic eastward traveling, baroclinic mid-latitude cyclone forming in western Europe, and the classic eastward-traveling, warm core tropical cyclone developing in the western Pacific. The analyses use high resolution, nonhydrostatic model simulations, satellite data, and various types of ground data to conduct the study. The flood events of Piemonte- 2000 in northern Italy and Typhoon Rusa-2002 in South Korea are selected to focus the analysis on well documented meteorological events.

  10. Extra-tropical cyclones in the present and future climate: a review

    Microsoft Academic Search

    U. Ulbrich; G. C. Leckebusch; J. G. Pinto

    2009-01-01

    Based on the availability of hemispheric gridded data sets from observations, analysis and global climate models, objective\\u000a cyclone identification methods were developed and applied to these data sets. Due to the large amount of investigation methods\\u000a combined with the variety of different datasets, a multitude of results exist, not only for the recent climate period but\\u000a also for the next

  11. Impact of tropical cyclones on the tropospheric water and energy cycle at synoptic scale : a case study

    NASA Astrophysics Data System (ADS)

    Garot, Thomas; Brogniez, Hélène; Viltard, Nicolas

    2015-04-01

    Typhoon Bopha, formed on November 25 and dissipated on December 9, 2012. It was the strongest tropical cyclone to ever hit the southern Philippine island of Mindanao, making landfall as a Category 5 super typhoon with winds of 280 km/h. During the life cycle of the typhoon, the satellite Megha-Tropiques provided 2 to 5 samplings of the tropical atmosphere per day, thanks to its low inclination orbit (20°). At that time, the two microwave radiometers SAPHIR and MADRAS were both performing measurements thus giving the opportunity to investigate(i) how the typhoon impacted the atmospheric humidity of its environment and (ii) the temporal evolution of its rain field. For this purpose, three different level of upper tropospheric humidity retrieved from SAPHIR, rain rates and releases of total latent heat estimated from MADRAS were monitored along the track. We discussed the mean behavior of the typhoon that shows strong lagged oscillations of humidity and convection during its life cycle and we deepened its spatial asymetries and their relationship with the close environment. This analysis was completed with the traking algorithm TOOCAN that allows to study how each individual convective clusters contributed to the life cycle of the typhoon.

  12. Objective analysis of tropical cyclone intensity, strength, and size using routine aircraft reconnaissance data

    E-print Network

    Stanfield, Charles Baynard

    1986-01-01

    representative set of data is obtained over a 13 month per1od for the entire spectrum of storms from tropical de- pression to super typhoon. These data are used to try to establish empirical pressure/wind relationsh1ps and a means of determining effec- tive... Comparison of the computed and observed maximum surface winds within 55 km of the center of a tropical depression 3 As Table 2, except for tropical storms. 4 As Table 2, except for typhoons 5 As Table 2, except for super typhoons 24 25 26 27 6...

  13. An objective method for forecasting tropical cyclone intensity and motion using Nimbus-5 ESMR measurements and non-satellite derived descriptors

    NASA Technical Reports Server (NTRS)

    Hunter, H. E.; Rodgers, E. B.; Shenk, W. E.

    1979-01-01

    An empirical analysis program, based on finding an optimal representation of the data was applied to 120 observations of 29 1973 and 1974 North Pacific tropical cyclones. Each observation consists of a field of Nimbus-5 Electrically Scanning Microwave Radiometer radiation measurements at 267 grid points covering and surrounding the tropical cyclone plus nine other non-satellite derived discriptors. Forecast algorithms to estimate storm intensity and motion at 12, 24, 48, and 72 hours after each observation were developed using an independent eigen screening analysis. These algorithms were based on best track data. Independent testing of these algorithms showed that the performance of most of these algorithms were better than persistence and the algorithms forecasting 24, 48, and 72 hour maximum wind speed were better than those made operationally by the Joint Typhoon Warning Center for 1973 and 1974 that did not use best track data.

  14. Satellite Movie Shows Three Tropical Cyclones in Eastern Pacific - Duration: 37 seconds.

    NASA Video Gallery

    This animation of NOAA's GOES-Wast satellite imagery from August 2 through 4 shows the movement of Tropical Depression Genevieve (left) southwest of Hawaii, Hurricane Iselle (center) in the Eastern...

  15. The Impact of Tropical Cyclones on the Geomorphic Evolution of Bolivar Peninsula, TX

    E-print Network

    Hales, Billy

    2012-07-16

    Semivariogram Analysis ......................................................... 82 Fractal Scaling Range Analysis ............................................... 91 Shifting Window Analysis ...................................................... 96....25 Fractal analysis for Hurricane Ike ................................................. 92 Figure 3.26 Fractal analysis for Hurricane Rita. ............................................... 93 Figure 3.27 Fractal analysis for Tropical Storm Fay...

  16. Combining New Satellite Tools and Models to Examine Role of Mesoscale Interactions in Formation and Intensification of Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Simpson, Joanne; Pierce, H.; Ritchie, L.; Liu, T.; Brueske, K.; Velden, C.; Halverson, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The objective of this research is to start filling the mesoscale gap to improve understanding and probability forecasts of formation and intensity variations of tropical cyclones. Sampling by aircraft equipped to measure mesoscale processes is expensive, thus confined in place and time. Hence we turn to satellite products. This paper reports preliminary results of a tropical cyclone genesis and early intensification study. We explore the role of mesoscale processes using a combination of products from TRMM, QuikSCAT, AMSU, also SSM/I, geosynchronous and model output. Major emphasis is on the role of merging mesoscale vortices. These initially form in midlevel stratiform cloud. When they form in regions of lowered Rossby radius of deformation (strong background vorticity) the mesoscale vortices can last long enough to interact and merge, with the weaker vortex losing vorticity to the stronger, which can then extend down to the surface. In an earlier cyclongenesis case (Oliver 1993) off Australia, intense deep convection occurred when the stronger vortex reached the surface; this vortex became the storm center while the weaker vortex was sheared out as the major rainband. In our study of Atlantic tropical cyclones originating from African waves, we use QuikSCAT to examine surface winds in the African monsoon trough and in the vortices which move westward off the coast, which may or may not undergo genesis (defined by NHC as reaching TD, or tropical depression, with a west wind to the south of the surface low). We use AMSU mainly to examine development of warm cores. TRMM passive microwave TMI is used with SSM/I to look at the rain structure, which often indicates eye formation, and to look at the ice scattering signatures of deep convection. The TRMM precipitation radar, PR, when available, gives precipitation cross sections. So far we have detailed studies of two African-origin cyclones, one which became severe hurricane Floyd 1999, and the other reached TD2 in June 2000 and then died out. The atmosphere off West African is dry and stable. It becomes less so between June and September, as the SST and convection heat up. QuikSCAT shows the African monsoon trough and shear zone extend westward over the ocean to nearly 30 degrees West. The evidence is strong that the two cyclones had in common multiple midlevel mergers, which extended to the surface keeping the surface vortex strong. These continued until both systems were designated TD's by NHC. In the June 2000 case, the main reason for failure was the lower SST and dry, stable atmosphere. This is shown by the comparison of the equivalent potential temperature maps and profiles with those from pre-Floyd. In the vortex which became Floyd, QuikSCAT shows continuous importation of high theta e (warm, moist) air from the south. From September 2-8, this air flowed around the vortex center, building up a high theta-e pool to the north. Then late on September 9, a 100-km wide jet of high theta-e air penetrated the vortex core, a major convective burst' was observed, and an intensifying, more elevated warm core was seen on AMSU. Rapid pressure fall and wind intensification were underway by 0000 UTC on September 10. Floyd became a Hurricane at 1200 UTC on Sept 10, 1999, with successive convective bursts running the hurricane thermodynamic engine by intensifying the warm core. TD2 was a strong African vortex, sustained by moderate convection (up to about 12.5 km) offshore of Africa. It peaked on June 23, showing an apparent "eye" on passive microwave composites. However, it could not assemble the ingredients for a convective burst. Thus it failed to get the thermodynamic hurricane engine going before it moved too far west of the region of lowered Rossby radius. By June 26, cloud systems were dying out. On June 25, a surface vortex was no longer seen on QuikSCAT, although one continued above the surface on model profiles until June 27. One of our main findings so far is showing the role of the mesoscale vortex interactions in sustaining some African vortices far out in to t

  17. Use of AIRS-derived Products in Tropical Cyclone Intensity Analysis During the HS3 Field Experiment

    NASA Astrophysics Data System (ADS)

    Garms, E.; Knuteson, R. O.; Plokhenko, Y.; Smith, W.; Weisz, E.; Revercomb, H. E.; Ackerman, S. A.

    2012-12-01

    The high-resolution data collected during a field experiment is extremely valuable, but it is equally valuable to have observations that provide context for such in situ measurements. For this reason, satellite data coincident with observations taken from the Global Hawk UAVs during the Hurricane and Severe Storm Sentinel (HS3) field experiment are vital to a gaining a more complete understanding of tropical cyclone (TC) processes. The primary data used in this study are calibrated hyperspectral infrared radiances obtained from the NASA Atmospheric Infrared Sounder (AIRS), onboard the Aqua satellite. AIRS measures upwelling Earth-emitted infrared spectra using more than 2300 IR channels between 3.7 and 15.4 microns. Several products derived from this high-spectral resolution data are used in this study. These products include a 3-D cloud amount vertical profile (CAVP) product as well as temperature and water vapor profiles retrieved using a Dual-Regression algorithm (DR), both of which were developed at the University of Wisconsin-Madison Space Science and Engineering Center (SSEC) Cooperative Institute for Meteorological Satellite Studies (CIMSS). The CAVP product will be used to measure the slope of the cloud tops of rainbands in a tropical cyclone. Observations from the UW Scanning High-resolution Interferometer Sounder (S-HIS), NASA Micro Pulse Lidar (MPL), and NCAR dropsondes taken during the 2012 Hurricane and Severe Storm Sentinel (HS3) field experiment will be used to validate the rainband slope analysis and the DR retrievals. The methodology behind the TC rainband slope analysis, which is hypothesized to correlate with TC intensity, will be discussed. This product will then be used to obtain a TC intensity estimate, which will be compared to other accepted intensity estimates like the Advanced Dvorak Technique (ADT), Advanced Microwave Sounding Unit (AMSU), and Satellite Consensus (SATCON) estimates. Additionally, the DR product will be used to characterize the environment around the rainband for each case. The purpose of this study is to determine the usefulness of a TC rainband slope index derived from AIRS L1B radiances in TC intensity analysis and short-term intensity change prediction. Examples of the TC rainband slope analysis, statistics for intensity estimate agreement with accepted intensity indices, and a possible correlation with intensity change will be presented. Conclusions regarding the utility of this measure in passively determining real-time intensity and intensity change of a TC will be discussed, along with applications for the duration of the HS3 experiment.

  18. In situ evidence of rapid, vertical, irreversible transport of lower tropospheric air into the lower tropical stratosphere by convective cloud turrets and by larger-scale upwelling in tropical cyclones

    NASA Astrophysics Data System (ADS)

    Danielsen, Edwin F.

    1993-05-01

    The STEP tropical objectives were successfully met during the flight experiments conducted from Darwin, Australia, January 16 to February 16, 1987. Necessary and sufficient measurements were made in, above, and downwind from very cold cirrus clouds, produced by three convective cloud types, to demonstrate irreversible mass transports into and dehydration in the lower tropical stratosphere. The three types are defined and described in terms of the physical processes that produce them and illustrated by examples derived from in situ and remote measurements. Intense solar heating is shown to produce, in addition to the usual vertical, sea breeze circulations normal to the coastline, an unusual pair of continental spanning, horizontal circulations. An upper tropospheric-lower stratospheric anti cyclonic circulation, inclined upward toward the tropics, contributes to the dehydration of dissipating cirrus anvils and intensifies the upper level, tropical easterlies. The lower tropospheric cyclonic circulation with tropical westerlies and extratropical easterlies is in direct conflict with the normal tropical easterlies and extratropical westerlies. Impulsive switches between these two opposing lower-level wind systems create conditions favorable for each of these cloud types and explain the summer season's aperiodic variability.

  19. Retrieval of Hydrometeor Profiles in Tropical Cyclones and Convection from Combined Radar and Radiometer Observations

    E-print Network

    Jiang, Haiyan

    ) found that the TRMM version-5 radiometer- only 2A12 algorithm (Kummerow et al. 1996) obtains of understanding the global energy and water cycles by providing four-dimensional distributions of latent heat- ing budgets. The latent heat release in tropical cy- clones provides heating and produces a warm

  20. An Observational Study of Tropical Cyclone Spinup in Supertyphoon Jangmi (2008) from 24 to 27 September

    E-print Network

    Smith, Roger K.

    2008-01-01

    using dropsondes, in situ flight-level data, satellite imagery, and Electra Doppler Radar (ELDORA in Tropical Storm Jangmi reveals multiple rotating updrafts near the de- veloping eye beneath cold cloud top s21 . The analysis of the corresponding infrared satellite imagery suggests that vortical updrafts

  1. Interannual variability of tropical cyclone activity in the southern South China Sea

    Microsoft Academic Search

    Zabani M. Zuki; Anthony R. Lupo

    2008-01-01

    A study of tropical storm activity in the southern South China Sea region was carried out for the period of 1960 to 2006 using data obtained from the UNISYS website archive, which was provided to them from the Joint Typhoon Warning Center (JWTC) best track data. This study was motivated by two particularly costly storms that impacted Malaysia during the

  2. 'Electrically-Hot' Convection and Tropical Cyclone Development in the Eastern Atlantic

    NASA Technical Reports Server (NTRS)

    Leppert, Kenneth, II; Petersen, Walter A.; Williams, Earle

    2008-01-01

    The depth and intensity of convective-scale "hot" towers in intensifying tropical disturbances has been hypothesized to play a role in tropical cyclogenesis via dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this investigation we investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") resident in African Easterly Waves (AEW) may play in tropical cyclogenesis over the eastern Atlantic Ocean. NCEP reanalysis data for the months of July to November for the years 2004, 2006, and 2007 are analyzed for the domain of 5 N - 15 N and 500W - 300 E. Specifically, NCEP data for individual AEWs are partitioned into northerly, southerly, trough, and ridge phases using the 700 hPa meridional winds. Subsequently, information from National Hurricane Center storm reports were divided up into developing and non-developing waves (i.e. tropical cyclogenesis). Finally, composites were created of developing and non-developing waves using the NCEP variables, but with the inclusion of lightning flash count and infrared brightness temperature information. The Zeus and World Wide Lightning Location Network lightning data were used for the lightning information, and the IR brightness temperature data was extracted from the NASA global-merged infrared brightness temperature dataset.

  3. Global representation of tropical cyclone-induced ocean thermal changes using Argo data - Part 1: Methods and results

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Zhu, J.; Sriver, R. L.

    2014-12-01

    Argo floats are used to examine tropical cyclone (TC)-induced ocean thermal changes on the global scale by comparing temperature profiles before and after TC passage. We present a footprint method that analyzes cross-track thermal responses along all storm tracks during the period 2004-2012. We combine the results into composite representations of the vertical structure of the average thermal response for two different categories: tropical storms/depressions (TS/TD) and hurricanes. The two footprint composites are functions of three variables: cross-track distance, water depth and time relative to TC passage. We find that this footprint strategy captures the major features of the upper-ocean thermal response to TCs on time scales up to 20 days when compared against previous case study results using in situ measurements. Further, TC effects are distinguishable from background sampling variability, but the significance of this result depends on differences in regional oceanic conditions and the intensity of the TC events. On the global scale, results indicate that hurricanes induce strong upwelling near the storm center, along with downwelling away from the storm, during the first 3 days after storm passage. We also find significant subsurface warming between 30 and 200 m depth for both hurricanes and TS/TDs. On average, the subsurface ocean response persists along storm tracks for up to 20 days down to 200 (400) m depth for TS/TD (Hurricanes), exhibiting peak warming of 0.4 °C at 60 m for hurricanes and 0.2 °C at 35 m for TS/TD. The footprint method shows a weak cooling response between 200 and 400 m, which is significant for Hurricanes but not for TS/TD.

  4. Doppler Radar and Cloud-to-Ground Lightning Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Buechler, Dennis; Cammarata, Michael; Arnold, James E. (Technical Monitor)

    2002-01-01

    Data from a single WSR-88D Doppler radar and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak within Tropical Storm Beryl's remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 12 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 hours, spawning tornadoes over a time period spanning approximately 6.5 hours. Time-height analyses of the three strongest supercells are presented in order to document storm kinematic structure and evolution. These Beryl mini-supercells were comparable in radar-observed intensity but much more persistent than other tropical cyclone-spawned tornadic cells documented thus far with Doppler radars. Cloud-to-ground lightning data are also examined for all the tornadic cells in this severe swarm-type tornado outbreak. These data show many of the characteristics of previously reported heavy-precipitation supercells. Lightning rates were weak to moderate, even in the more intense supercells, and in all the storms the lightning flashes were almost entirely negative in polarity. No lightning at all was detected in some of the single-tornado storms. In the stronger cells, there is some evidence that lightning rates can decrease during tornadogenesis, as has been documented before in some midlatitude tornadic storms. A number of the storms spawned tornadoes just after producing their final cloud-to-ground lightning flashes. These findings suggest possible benefits from implementation of observing systems capable of monitoring intracloud as well as cloud-to-ground lightning activity.

  5. A Stealth Thermal Control by El Niño on Intense Tropical Cyclones in the Central and Eastern Pacific

    NASA Astrophysics Data System (ADS)

    Boucharel, J.; Jin, F. F.; Lin, I. I.

    2014-12-01

    The El Niño Southern Oscillation (ENSO) phenomenon, which features strong oceanic surface warming over the equatorial eastern Pacific, has major climatic and societal impacts. In particular, it greatly influences the yearly variations of tropical cyclone (TC) activities in both the Pacific and Atlantic basins via atmospheric dynamical factors such as vertical wind shear and stability. Until recently the direct ocean thermal control of ENSO on TCs has not been taken into consideration because of a mismatch in both timing and location. ENSO peaks in winter and the warming occurs along the equator, a region without TC activity. Here, we present evidence that El Niño discharges its heat into the eastern north Pacific basin 2-3 seasons after it peaks. This basin is characterized by abundant TC activity and is the second most active TC region in the world. As a result, an "El Niño heat reservoir" underneath the ocean surface is delivered to this basin during the TC season (boreal summer/fall) following the winter time peak of El Niño. ENSO exerts a delayed and stealth ocean thermal control on the overlying TCs that can draw the heat out from below the ocean surface, which provides an additional ocean heat supply favorable for the formation of hurricanes with strong intensities. This thermal control on intense TC variability has significant implications for seasonal predictions and long-term projections of TC activity over the eastern north Pacific.

  6. Introduction to Suomi national polar-orbiting partnership advanced technology microwave sounder for numerical weather prediction and tropical cyclone applications

    NASA Astrophysics Data System (ADS)

    Weng, F.; Zou, X.; Wang, X.; Yang, S.; Goldberg, M. D.

    2012-10-01

    The Suomi National Polar-orbiting Partnership (NPP) satellite was successfully launched on 28 October 2011. On board the Suomi NPP, the Advanced Technology Microwave Sounder (ATMS) is a cross-track scanning instrument and has 22 channels at frequencies ranging from 23 to 183 GHz which allows for probing the atmospheric temperature and moisture under clear and cloudy conditions. ATMS inherited most of the sounding channels from its predecessors: Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Humidity Sounder (MHS) onboard NOAA and MetOp satellites. However, ATMS has a wider scan swath and has no gaps between two consecutive orbits. It includes one new temperature sounding channel and two water vapor sounding channels and provides more details of thermal structures in lower troposphere, especially for the storm conditions such as tropical cyclones. While ATMS temperature sounding channels have shorter integration time and therefore higher noise than AMSU-A, the ATMS observations from their overlapping field of views are resampled to produce AMSU-A-like measurements.

  7. Impacts of decaying eastern and central Pacific El Niños on tropical cyclone activities over the western North Pacific in summer

    NASA Astrophysics Data System (ADS)

    Yang, Yuxing; Xie, Ruihuang; Wang, Faming; Huang, Fei

    2015-05-01

    We investigate the influences of the decaying eastern Pacific El Niño (EP-El Niño) and central Pacific El Niño (CP-El Niño) on tropical cyclone (TC) activities in the western North Pacific (WNP) during July, August, and September (JAS). During this period, TC geneses and tracks are reduced in the central and eastern WNP. However, TC tracks reaching the Philippines increase, and more TC geneses appear west of 145°E during EP-El Niño. During CP-El Niño, tracks reaching the South China Sea (SCS) and southeast coast of China increase, and positive anomalies of TC genesis are found in the southern part of the central WNP and southern SCS. It is possible that the different variations of the anomalous anticyclone over east of the Philippines in the WNP induced by El Niños are instrumental to the different TC variations in the two types of decaying El Niños during JAS. Compared with EP-El Niño, strengthening and northward expansion of the anomalous anticyclone during CP-El Niño cause a westward shift of the western Pacific subtropical high in summer, which is responsible for more westward TC tracks over the SCS and southeast coast of China. This northward expansion can cause the center of suppressed TC geneses in the central WNP to migrate further north during CP-El Niño. A decreased magnitude of vertical shear dominates the southern part of the central WNP and southern SCS, which enhances TC formation in these regions during CP-El Niño.

  8. CloudSat & A-Train Observations of Tropical Cyclones: Examining Effects of Wind Shear on Storm Structure

    NASA Astrophysics Data System (ADS)

    Tourville, N. D.; Knaff, J. A.; Demaria, M.; Stephens, G. L.; Vane, D.

    2014-12-01

    CloudSat (CS) heralded a new era of profiling the planet's cloud systems and storms with its launch in 2006. This satellite flies the first 94 GHz spaceborne cloud profiling radar and the data collected has provided a unique perspective on Earth's cloudiness and processes that affect clouds. While passes of the nadir-pointing CPR antenna occur infrequently over tropical cyclones (TCs), they happen enough to provide a detailed compilation of the inner structure of clouds and precipitation of these complex storm systems. Over 8,000 vertical profiles of TCs have been collected during the period June 2006 through June 2014 and observations continue as CS flies in daylight only mode. Each unique overpass profiled by CS has been compiled with corresponding A-Train sensors, model data and storm specific best track information.With the volume of data collected, it is possible to composite TC structure information with respect to various environmental parameters that are known to have a controlling influence on storms. To illustrate this characteristic of the data, we show composites of the vertical structure of TCs as a function of environmental wind shear. Observations of wind shear at varying levels (for example 200-850 mb) and TC composites relative to the direction of the larger scale shear will be examined and discussed in detail.

  9. Increased threat of island endemic tree's extirpation via invasion-induced decline of intrinsic resistance to recurring tropical cyclones.

    PubMed

    Marler, Thomas E

    2013-01-01

    Cycas micronesica populations in Guam have been threatened by the invasion of the armored scale Aulacaspis yasumatsui. I integrate four factors that illuminate an acute need for intervention to reduce an unprecedented threat caused by the invasion. First, mechanical failure of healthy C. micronesica trees during catastrophic winds is rare because of the cycad tree's unique pachycaulis stem design. Second, tree-winching and three-point bend stress tests revealed the natural resistance to damage from tropical cyclones has been compromised by the chronic feeding of this homopteran pest. Third, no typhoon event has occurred since the arthropod's invasion and its spread in the year 2005 to actually test extent of mechanical failure for the unhealthy remaining trees. Fourth, historical records indicate the probability that Guam will experience typhoon force winds is 0.51 in three years and 0.91 in 10 y. These four factors integrate to predict the next typhoon may eliminate the surviving C. micronesica trees and stewardship of this declining population requires intervention to counter this prediction. PMID:23802037

  10. Effects of tropical cyclones on large-scale circulation and ocean heat transport in the South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, Xidong; Wang, Chunzai; Han, Guijun; Li, Wei; Wu, Xinrong

    2014-12-01

    In this study, we investigate the influence of tropical cyclones (TCs) on large-scale circulation and ocean heat transport in the South China Sea (SCS) by using an ocean general circulation model at a 1/8° resolution during 2000-2008. The model uses a data assimilation system to assimilate observations in order to improve the representation of SCS circulation. The results reveal an unexpected deep SCS circulation anomaly induced by TCs, which suggests that effects of TC can penetrate deeper into the ocean. This deep effect may result from the near inertial oscillations excited by TCs. The inertial oscillations can propagate downward to the oceanic interior. The analyses confirm that TCs have two effects on ocean heat transport of the SCS. Firstly, the wind stress curl induced by TCs affects the structure of SCS circulation, and then changes heat transport. Secondly, TCs pump surface heat downward to the thermocline, increasing the heat injection from the atmosphere to the ocean. Two effects together amplify the outflow of the surface heat southward away the SCS through the Mindoro and Karimata Straits. The TC-induced heat transports through the Mindoro, Balabac and Karimata Straits account for 20 % of the total heat transport through three straits. An implication of this study is that ocean models need to simulate the TC effect on heat transport in order to correctly evaluate the role of the SCS through flow in regulating upper ocean circulation and climate in the Indonesian maritime continent and its adjacent regions.

  11. Relationship between tropical cyclone activities in the Northwest Pacific area and the summer monsoon rainfall in the Northeast Asian region

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Cha, Yu-Mi; Kang, Sung-Dae; Kim, Hae-Dong

    2014-08-01

    This study analyzed the effects of thermal differences between land and the sea on tropical cyclone (TC) activity. To this end, northern China in which thermal ridges appear in summer in the continent east of Asia was defined as "Land" and an area of the sea where temperatures are low in the tropical and subtropical western North Pacific was defined as "Sea" to analyze the time series of thermal differences between the land and the sea over the last 62 years. Change-point analysis was applied to these time series. According to the results, a significant climate regime shift existed in 1978. That is, positive values were distributed from 1951 to 1978 (5178) and negative values were distributed from 1979 to 2012 (7912). Thereafter, average differences between the 5178 period during which positive values were apparent and the 7912 period during which negative values were apparent was analyzed. With regard to TC genesis, TCs during the 7912 period showed a tendency of being mainly formed in the northwestern quadrant of the tropical and subtropical western North Pacific, and those during the 5178 period showed a tendency of being mainly formed in the southeastern quadrant. With regard to TC movements, whereas TCs during the 7912 period showed a pattern of moving west from the Philippines toward the Indochina peninsular and southern China, those during the 5178 period showed a pattern of moving north from the far southeastern sea of the Philippines to pass the East China Sea and go toward Korea and Japan. Therefore, the TCs during the 7912 period showed a tendency of being formed and moving in regions further west than those of the TCs during the 5178 period. With regard to TC intensities during the two periods, TCs during the 5178 period were more intense. Large-scale environments that affected these changes in TC activity between the two periods were analyzed. During the 7912 period, since temperature in the continent were lower than those in the sea, anomalous anticyclones were reinforced in the continent East of Asia and anomalous cyclones were reinforced in the sea. Consequently, anomalous northerlies were reinforced in a region ranging from the middle-latitude region in East Asia to the Indochina peninsular so that TCs could not move to the middle-latitude region in East Asia but moved west toward the Indochina peninsular and southern China during this period. Eventually, during the 7912 period, temperatures in the land were higher than those in the sea to show the west high east low anomalous pressure system patterns so that western North Pacific subtropical highs could not develop and thus the steering flows of anomalous southerlies that would move TCs to the middle-latitude region in East Asia were weak. These results were identified from 600 hPa relative humidity, 200-850 hPa vertical wind shears, and differences in sea surface temperatures between the two periods.

  12. [Summary of Research on Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 meters per second and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of, rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify. Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast. The structures of the highly sheared tropical storm Chantal During CAMEX-4 is also discussed.

  13. The Human Impact of Tropical Cyclones: a Historical Review of Events 1980-2009 and Systematic Literature Review

    PubMed Central

    Doocy, Shannon; Dick, Anna; Daniels, Amy; Kirsch, Thomas D.

    2013-01-01

    Background. Cyclones have significantly affected populations in Southeast Asia, the Western Pacific, and the Americas over the past quarter of a century. Future vulnerability to cyclones will increase due to factors including population growth, urbanization, increasing coastal settlement, and global warming. The objectives of this review were to describe the impact of cyclones on human populations in terms of mortality, injury, and displacement and, to the extent possible, identify risk factors associated with these outcomes. This is one of five reviews on the human impact of natural disasters. Methods. Data on the impact of cyclones were compiled using two methods, a historical review from 1980 to 2009 of cyclone events from multiple databases and a systematic literature review of publications ending in October 2012. Analysis included descriptive statistics and bivariate tests for associations between cyclone characteristics and mortality using Stata 11.0. Findings. There were 412,644 deaths, 290,654 injured, and 466.1 million people affected by cyclones between 1980 and 2009, and the mortality and injury burden was concentrated in less developed nations of Southeast Asia and the Western Pacific. Inconsistent reporting suggests this is an underestimate, particularly in terms of the injured and affected populations. The primary cause of cyclone-related mortality is drowning; in developed countries male gender was associated with increased mortality risk, whereas females experienced higher mortality in less developed countries. Conclusions. Additional attention to preparedness and early warning, particularly in Asia, can lessen the impact of future cyclones. PMID:23857074

  14. The human impact of tropical cyclones: a historical review of events 1980-2009 and systematic literature review.

    PubMed

    Doocy, Shannon; Dick, Anna; Daniels, Amy; Kirsch, Thomas D

    2013-01-01

    Background. Cyclones have significantly affected populations in Southeast Asia, the Western Pacific, and the Americas over the past quarter of a century. Future vulnerability to cyclones will increase due to factors including population growth, urbanization, increasing coastal settlement, and global warming. The objectives of this review were to describe the impact of cyclones on human populations in terms of mortality, injury, and displacement and, to the extent possible, identify risk factors associated with these outcomes. This is one of five reviews on the human impact of natural disasters. Methods. Data on the impact of cyclones were compiled using two methods, a historical review from 1980 to 2009 of cyclone events from multiple databases and a systematic literature review of publications ending in October 2012. Analysis included descriptive statistics and bivariate tests for associations between cyclone characteristics and mortality using Stata 11.0. Findings. There were 412,644 deaths, 290,654 injured, and 466.1 million people affected by cyclones between 1980 and 2009, and the mortality and injury burden was concentrated in less developed nations of Southeast Asia and the Western Pacific. Inconsistent reporting suggests this is an underestimate, particularly in terms of the injured and affected populations. The primary cause of cyclone-related mortality is drowning; in developed countries male gender was associated with increased mortality risk, whereas females experienced higher mortality in less developed countries. Conclusions. Additional attention to preparedness and early warning, particularly in Asia, can lessen the impact of future cyclones. PMID:23857074

  15. The role of tropical cyclones on landscape dynamics in southern Baja California, Mexico based on Late Pleistocene-Holocene alluvial stratigraphy

    NASA Astrophysics Data System (ADS)

    McDonald, Eric; Antinao, Jose Luis; Rhodes, Edward J.; Brown, Nathan; Gosse, John

    2015-04-01

    Region-wide alluvial records provide evidence that time-transgressive changes in climate can be a major driver of landscape evolution. Historically, landfall of eastern Pacific tropical cyclones in southwestern North America during the late summer and early fall provide the strongest storms that have demonstrated geomorphic impact on the landscape. The alluvial fan record of the southern portion of Baja California (Mexico) was investigated to determine if linkages exist between region-wide fluvial deposits and tropical cyclones. The regional distribution and Pleistocene to Holocene morphostratigraphy of alluvial fans has been established for the southern portion of Baja California with primary focus on the La Paz and San José del Cabo basins. Six discrete morphopedosedimentary alluvial units (Qt1 through Qt6) were differentiated across the region using a combination of geomorphologic mapping, sedimentological analysis, and soil development further reinforced with geochronology using radiocarbon, optically stimulated luminescence and cosmogenic depth-profiles. A first phase of regional aggradation began before ~ 100 ka (Qt1) and culminated ~10 ka (Qt4). After deposition of Qt4, increasing regional incision of older units and the progressive development of a channelized alluvial landscape coincide with deposition of Qt5 and Qt6 units in a second, incisional phase. All units are conformed of multiple 1-3 m thick alluvial packages deposited in upper-flow regime and representing individual storms. Aggradational units (Qt1-Qt4) covered broad (>2 km) channels in the form of sheetflood deposition while incisional stage deposits are mostly confined to channels of ~0.5-2 km width. Continuous deposition of the thicker sequences is demonstrated by closely spaced luminescence dates in vertical profiles. In a few places disconformities between major units are evident and indicated by partly eroded buried soils. Analysis of historical terraces as part of the younger units incised into older fans show that deposition was accomplished by large tropical cyclone events. Older units feature the same sedimentological traits as these historical deposits. We interpret the whole sequence as indicating discrete periods during the Late Pleistocene and Holocene when climatic conditions allowed large tropical cyclone events that today are not expressed. These discrete periods can be associated with specific periods when (a) insolation at the Equator was at peaks determined by precessional cycles and (b) the Tropical Pacific might have shown a state similar to that currently displayed during El Niño events.

  16. The NASA Real Time Mission Monitor - A Situational Awareness Tool for Conducting Tropical Cyclone Field Experiments

    NASA Technical Reports Server (NTRS)

    Goodman, Michael; Blakeslee, Richard; Hall, John; Parker, Philip; He, Yubin

    2008-01-01

    The NASA Real Time Mission Monitor (RTMM) is a situational awareness tool that integrates satellite, aircraft state information, airborne and surface instruments, and weather state data in to a single visualization package for real time field experiment management. RTMM optimizes science and logistic decision-making during field experiments by presenting timely data and graphics to the users to improve real time situational awareness of the experiment's assets. The RTMM is proven in the field as it supported program managers, scientists, and aircraft personnel during the NASA African Monsoon Multidisciplinary Analyses (investigated African easterly waves and Tropical Storm Debby and Helene) during August-September 2006 in Cape Verde, the Tropical Composition, Cloud and Climate Coupling experiment during July-August 2007 in Costa Rica, and the Hurricane Aerosonde mission into Hurricane Noel in 2-3 November 2007. The integration and delivery of this information is made possible through data acquisition systems, network communication links, and network server resources built and managed by collaborators at NASA Marshall Space Flight Center (MSFC) and Dryden Flight Research Center (DFRC). RTMM is evolving towards a more flexible and dynamic combination of sensor ingest, network computing, and decision-making activities through the use of a service oriented architecture based on community standards and protocols. Each field experiment presents unique challenges and opportunities for advancing the functionality of RTMM. A description of RTMM, the missions it has supported, and its new features that are under development will be presented.

  17. [Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance fights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 m/s and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of: rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intense.

  18. Quasi-Equilibria of the Rotunno-Emanuel Tropical Cyclone Model

    NASA Technical Reports Server (NTRS)

    Chao, Winston C.; Chen, Baode

    2003-01-01

    Long-term integrations using the Rotunno-Emanuel (RE) model demonstrate that given sufficient elapsed time the weak initial vortex specified by R E can also lead to tropical cyclogenesis, albeit at a slower growth rate. Thus the RE notion of the finite-amplitude nature of tropical cyclogenesis is valid only if the period of examination is limited to the first eight days. These results also show that, if initial vortex as specified by RE is used, prior to cyclogenesis the model state does not resemble the observed pre-genesis disturbances in the sense that there is no precipitation in the center of the disturbance. Another experiment using the same model but with the initial vortex replaced by a disturbance with a different structure shows that a state resembling the observed pre-genesis disturbances can be simulated and this state can lead to spontaneous cyclogenesis, a rapid transition between two quasi-equilibria. This spontaneous cyclogenesis is associated with the generation of a new convective region at large radius and its subsequent contraction, which reminds one of the observed eye-wall replacement, but the distinction from the latter is obvious.

  19. ENSO Effect on East Asian Tropical Cyclone Landfall via Changes in Tracks and Genesis in a Statistical Model

    NASA Technical Reports Server (NTRS)

    Yonekura, Emmi; Hall, Timothy M.

    2014-01-01

    Improvements on a statistical tropical cyclone (TC) track model in the western North Pacific Ocean are described. The goal of the model is to study the effect of El Nino-Southern Oscillation (ENSO) on East Asian TC landfall. The model is based on the International Best-Track Archive for Climate Stewardship (IBTrACS) database of TC observations for 1945-2007 and employs local regression of TC formation rates and track increments on the Nino-3.4 index and seasonally varying climate parameters. The main improvements are the inclusion of ENSO dependence in the track propagation and accounting for seasonality in both genesis and tracks. A comparison of simulations of the 1945-2007 period with observations concludes that the model updates improve the skill of this model in simulating TCs. Changes in TC genesis and tracks are analyzed separately and cumulatively in simulations of stationary extreme ENSO states. ENSO effects on regional (100-km scale) landfall are attributed to changes in genesis and tracks. The effect of ENSO on genesis is predominantly a shift in genesis location from the southeast in El Nino years to the northwest in La Nina years, resulting in higher landfall rates for the East Asian coast during La Nina. The effect of ENSO on track propagation varies seasonally and spatially. In the peak activity season (July-October), there are significant changes in mean tracks with ENSO. Landfall-rate changes from genesis- and track-ENSO effects in the Philippines cancel out, while coastal segments of Vietnam, China, the Korean Peninsula, and Japan show enhanced La Nina-year increases.

  20. Finding Tropical Cyclones on a Cloud Computing Cluster: Using Parallel Virtualization for Large-Scale Climate Simulation Analysis

    SciTech Connect

    Hasenkamp, Daren; Sim, Alexander; Wehner, Michael; Wu, Kesheng

    2010-09-30

    Extensive computing power has been used to tackle issues such as climate changes, fusion energy, and other pressing scientific challenges. These computations produce a tremendous amount of data; however, many of the data analysis programs currently only run a single processor. In this work, we explore the possibility of using the emerging cloud computing platform to parallelize such sequential data analysis tasks. As a proof of concept, we wrap a program for analyzing trends of tropical cyclones in a set of virtual machines (VMs). This approach allows the user to keep their familiar data analysis environment in the VMs, while we provide the coordination and data transfer services to ensure the necessary input and output are directed to the desired locations. This work extensively exercises the networking capability of the cloud computing systems and has revealed a number of weaknesses in the current cloud system software. In our tests, we are able to scale the parallel data analysis job to a modest number of VMs and achieve a speedup that is comparable to running the same analysis task using MPI. However, compared to MPI based parallelization, the cloud-based approach has a number of advantages. The cloud-based approach is more flexible because the VMs can capture arbitrary software dependencies without requiring the user to rewrite their programs. The cloud-based approach is also more resilient to failure; as long as a single VM is running, it can make progress while as soon as one MPI node fails the whole analysis job fails. In short, this initial work demonstrates that a cloud computing system is a viable platform for distributed scientific data analyses traditionally conducted on dedicated supercomputing systems.

  1. A prediction scheme with genetic neural network and Isomap algorithm for tropical cyclone intensity change over western North Pacific

    NASA Astrophysics Data System (ADS)

    Huang, Ying; Jin, Long

    2013-08-01

    A western North Pacific tropical cyclone (TC) intensity prediction scheme has been developed based on climatology and persistence (CLIPER) factors as potential predictors and using genetic neural network (GNN) model. TC samples during June-October spanning 2001-2010 are used for model development. The GNN model input is constructed from potential predictors by employing both a stepwise regression method and an Isometric Mapping (Isomap) algorithm. The Isomap algorithm is capable of finding meaningful low-dimensional architectures hidden in their nonlinear high-dimensional data space and separating the underlying factors. In this scheme, the new developed model, which is termed the GNN-Isomap model, is used for monthly TC intensity prediction at 24- and 48-h lead times. Using identical modeling samples and independent samples, predictions of the GNN-Isomap model are compared with the widely used CLIPER method. By adopting different numbers of nearest neighbors, results of sensitivity experiments show that the mean absolute prediction errors of the independent samples using GNN-Isomap model at 24- and 48-h forecasts are smaller than those using CLIPER method. Positive skills are obtained as compared to the CLIPER method with being above 12 % at 24 h and above 14 % at 48 h. Analyses of the new scheme suggest that the useful linear and nonlinear prediction information of the full pool of potential predictors is excavated in terms of the stepwise regression method and the Isomap algorithm. Moreover, the GNN is built by integrating multiple individual neural networks with the same expected output and network architecture is optimized by an evolutionary genetic algorithm, so the generalization capacity of the GNN-Isomap model is significantly enhanced, indicating a potentially better operational weather prediction.

  2. Tropical cyclones in the North American Regional Reanalysis: An assessment of spatial biases in location, intensity, and structure

    NASA Astrophysics Data System (ADS)

    Zick, Stephanie E.; Matyas, Corene J.

    2015-03-01

    Long-term reanalysis data sets, such as the North American Regional Reanalysis (NARR) and Climate Forecast System Reanalysis (CFSR), are data-rich resources for weather and climate research. However, investigations into tropical cyclone (TC) structures are lacking. This study examines position, intensity, and structure of U.S. landfalling TCs in these data sets during 1998-2012. TC positions are determined using three dynamic and thermodynamic parameters. In NARR, positions are problematic near the domain boundary but show statistically significant improvements compared with CFSR in regions over the U.S. and near its coastlines. TC intensity is universally underestimated in both data sets, yet the pressure-wind relationship is reasonably maintained. NARR and CFSR intensities are highly correlated (r = 0.93), suggesting that these data sets are limited in a similar fashion in their generation of intensity and that advanced data assimilation techniques are unable to overcome the shortcomings of low resolutions. To investigate TC structure, a 10-storm composite is constructed using the most intense model TCs at peak intensity. Both models develop robust warm cores (T' ~ 6-7 K), but the radius of maximum winds (>100 km) is too broad compared with storms in nature. Secondary circulation features in NARR are more realistic, particularly the shallow inflow layer, vertical motion in the inner core, and confined outflow in the upper troposphere. Results indicate that, over the U.S. and near its coastline, NARR positions and structure are competitive with or slightly improved upon CFSR. Away from the domain boundary, NARR is a suitable resource for evaluating TC positions and certain aspects of the secondary circulation.

  3. The Modulation and Decadal Change of Madden-Julian Oscillation on Tropical Cyclone in the Western North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Zhao, W.

    2014-12-01

    This study focuses on the climatological relationship between the Modden-Julian Oscillation (MJO) and Tropical Cyclone (TC) activity in the Western North Pacific (WNP) and its decadal variability. Based on the knowledge of the modulation of MJO on TC in WNP, a set of data including the RMM(Real-time Multivariate MJO)index from RMRC(bureau of meteorology)of the Centre for Australian Weather and Climate Research,the best tracks from the Navy Joint Typhoon Warming Center(JTWC),daily data of the NCEP/NCAR reanalysis and the ECMWF ERA-interim reanalysis were used.The result shows that TC frequency in WNP exhibited a statistically significant decrease during the period of 1998-2010, comparing to the period of 1979-1997.The decrease on TC frequency in WNP mainly occured during MJO active phases 4,5,6,and 7. In further investigation on comparison of cycle days of MJO, duration of MJO active phases (4,5,6,and 7),low-frequency wind at 850hPa, large-scale convection circulation and vatiability of Surface Sea Temperatures (SST) and Outgoing Longwave Radiation (OLR) in MJO active phases between 1979-1997 and 1998-2010, we found that: during 1998-2010,cycle days of MJO and duration of MJO active phases exhibited a significant decrease; low-frequency wind at 850hPa showed an eastern-wind transition; convective areas in MJO active phases decreased and anormaly of its SST were more negative. These may be reasons of difference of TC frequency in the period of 1979-1997 and 1998-2010.

  4. Cyclone shelters and cyclone resilient design in coastal areas of Bangladesh

    E-print Network

    Jia, Zheng, M.C.P. Massachusetts Institute of Technology

    2012-01-01

    Bangladesh is one of those countries that are most vulnerable to tropical cyclones. In recent decades, cyclone mitigations by the Government of Bangladesh and international organizations have greatly increased the coastal ...

  5. [Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones]. [Structure of the HighIy Sheared Tropical Stom Chantal During CAMEX-4

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Tropical Storm Chantal during August 2001 was a storm that failed to intensify over the few days prior to making landfall on the Yucatan Peninsula. An observational study of Tropical Storm Chantal is presented using a diverse data set including remote and in situ measurements from the NASA ER-2 and DC-8 and the NOAA WP-3D N42RF aircraft and satellite data. The authors discuss the storm structure from the larger scale environment down to the convective scale. Large vertical shear (850-200 hPa shear magnitude range 8-15 m/s) plays a very important role in preventing Chantal from intensifying. The storm had a poorly defined vortex that only extended up to 5-6 km altitude, and an adjacent intense convective region that comprised an Mesoscale Convective System (MCS). The entire low-level circulation center was in the rain-free western side of the storm, about 80 km to the west-southwest of the MCS. The MCS appears to have been primarily the result of intense convergence between large scale, low-level easterly flow with embedded downdrafts, and the cyclonic vortex flow. The individual cells in the MCS such as Cell 2 during the period of the observations, were extremely intense with reflectivity core diameters of 10 km and peak updrafts exceeding 20 m/s. Associated with this MCS were two broad subsidence (warm) regions both of which had portions over the vortex. The first layer near 700 hPa was directly above the vortex and covered most of it. The second layer near 500 hPa was along the forward and right flanks of Cell 2 and undercut the anvil divergence region above. There was not much resemblance of these subsidence layers to typical upper level warm cores in hurricanes that are necessary to support strong surface winds and a low central pressure. The observations are compared to previous studies of weakly sheared storms and modeling studies of shear effects and intensification. The configuration of the convective updrafts, low-level circulation, and lack of vertical coherence between the upper and low level warming regions, likely inhibited intensification of Chantal. This configuration is consistent with modeling of vortices in sheared environments, which suggest strongest convection and rain in the downshear left quadrant of the storm, and subsidence in the upshear right quadrant. The vertical shear profile is however different from what was assumed in previous modeling in that the winds are strongest in the lowest levels and the deep tropospheric vertical shear is on the order of 10-12 m/s.

  6. The influence of African easterly waves on Atlantic tropical cyclone activity

    NASA Astrophysics Data System (ADS)

    Staehling, Erica M.

    A high-resolution global atmospheric model is used to disentangle the relationship between African easterly waves (AEWs) and Atlantic tropical storms (TCs) from the large-scale environmental factors that may obscure their connection. Since the two most cited references on AEW interannual variability in relation to TC activity draw conflicting conclusions about the historical relationship, and the AEW counts in each study do not show agreement on historical variability, novel analysis procedures are developed to produce consistent AEW and TC count statistics for the historical record using reanalysis products. This reanalysis-derived historical record is used to legitimize the model for the study of AEWs, which is subsequently utilized to investigate the relationship between AEWs and TCs. The internal variability of the relationship between AEW and TC count, including the sensitivity to ENSO phase and annual trends, and the interplay between environmental factors, AEW activity, and TC activity are probed using three sets of simulations: 1) climatological simulations, consisting of three ensemble members forced with historical seasonally and annually varying SST; 2) simulations with interannually invariant forcing, including a control simulation with climatological mean SST and a perpetual La Nina simulation with composite SST from strong La Nina years; 3) perturbed simulations, in which the large-scale environment is drastically altered through the manipulation of African albedo. Since variability exists in AEW count that is unexplained by known indicators of large-scale environmental favorability, across all simulations and multiple timescales, it is unlikely that the ubiquitous covariance between AEW and TC count is simply a response to environmental factors. The statistically significant correlations between AEW and TC statistics suggest that AEW variability accounts for a portion of the observed variability in TC count not due to known environmental factors, since there is unexplained variance in AEW count, and both individual years and aggregated model runs with more (fewer) AEWs also tend to have more (fewer) TCs. It is argued that while half of the covariance between AEW and TC count interannually is mediated by the large-scale environment, the other half can be attributed to stochastic AEW variability.

  7. Effect of Land and its Surface Characteristics on Tropical Cyclone Intensity and Structure - An idealized study using HWRF

    NASA Astrophysics Data System (ADS)

    Subramanian, S.; Gopalakrishnan, S. G.; Niyogi, D.; Marks, F., Jr.

    2012-12-01

    Although the upward transfer of enthalpy fluxes from the ocean surface to the atmosphere and the downward transfer of momentum from the atmosphere to ocean surface eventually controls the evolution and intensification of a Tropical Cyclone (TC) (Ooyama 1969; Anthes and Chang 1978; Tuleya and Kurihara 1978; Emanuel 1995), several TCs are known to sustain over land and some of them have even been found to intensify over land. Past studies have emphasized on the importance of land surface affecting storm development and have showed that anomalously wet conditions may sustain or strengthen the storm if the surface temperature is sufficiently high (Emanuel, 1995; Emanuel et al., 2004, 2008; Kellner et al., 2012; Tuleya, 1994). We explore the fundamental interactions between land surface and TC and aim to understand the mechanisms involved in the sustenance or strengthening of such hurricanes. This study uses the idealized framework of the operationally adopted Hurricane Weather Research and Forecasting system (HWRF) with similar setting as that of Gopalakrishnan et al., 2011, 2012. The TC simulated over an all ocean domain was designated as the control experiment. To simulate landfall and to study the land surface effects on TCs, land was included in the western half of the domain using various land use and soil categories from the USGS table. The results from various experiments were compared and the storm's development, secondary circulation involved in the storm, the role friction plays in the cyclone processes etc were studied with special focus on the land surface effects on TC. The TC development in the experiments with land mass was not as intense as in the control and the time evolution of storms for major cases is given in Figure 1. Montgomery et al., 2010 have explained the importance of surface drag on primary and secondary circulations in TCs over ocean. Results from this study also indicate stronger inflow makes for stronger storm as in Gopalakrishnan et al., 2012 The storm over the desert soil dissipated very quickly owing to the absence of moisture fluxes and presence of weak convergence at the hurricane boundary layer. Over wetland and land areas with high soil moisture content, the storms decayed slowly and maintained its structure for an appreciable time. They also showed a slight strengthening due to relatively high soil moisture and moisture convergence in the in-flow region due to the increase in friction. From preliminary analysis, it appears that friction might have a dual role to play - while Cd reduces the speed in the tangential direction, it tends to increase the inflow and this balance we think, is very crucial over land and work is in process to completely analyze results. Figure 1: Time history of the intensification process in an idealized storm: Hovemoller diagrams for axisymmetric mean tangential winds at a height of 10 m for runs with (left) only ocean, (center) desert soil, and (right) herbaceous wetlands.

  8. In situ evidence of rapid, vertical, irreversible transport of lower tropospheric air into the lower tropical stratosphere by convective cloud turrets and by larger-scale upwelling in tropical cyclones

    NASA Technical Reports Server (NTRS)

    Danielsen, Edwin F.

    1993-01-01

    The STEP tropical objectives were successfully met during the flight experiments conducted from Darwin, Australia, January 16 to February 16, 1987. Necessary and sufficient measurements were made in, above, and downwind from very cold cirrus clouds, produced by three convective cloud types, to demonstrate irreversible mass transports into and dehydration in the lower tropical stratosphere. The three types are defined and described in terms of the physical processes that produce them and illustrated by examples derived from in situ and remote measurements. Intense solar heating is shown to produce, in addition to the usual vertical, sea breeze circulations normal to the coastline, an unusual pair of continental spanning, horizontal circulations. An upper tropospheric-lower stratospheric anticyclonic circulation, inclined upward toward the tropics, contributes to the dehydration of dissipating cirrus anvils and intensifies the upper level, tropical easterlies. The lower tropospheric cyclonic circulation with tropical westerlies and extratropical easterlies is in direct conflict with the normal tropical easterlies and extratropical westerlies. Impulsive switches between these two opposing lower-level wind systems create conditions favorable for each of these cloud types and explain the summer season's aperiodic variability.

  9. Effects of Relative and Absolute Sea Surface Temperature on Tropical Cyclone Potential Intensity Using a Single-Column Model

    E-print Network

    cyclone energy (ACE) and power dissipation index (PDI), with a near doubling of PDI over about 35 years. If this relationship were to continue into the future, based on climate model projections the North Atlantic PDI would

  10. Forecasting surface wind speeds over offshore islands near Taiwan during tropical cyclones: Comparisons of data-driven algorithms and parametric wind representations

    NASA Astrophysics Data System (ADS)

    Wei, Chih-Chiang

    2015-03-01

    Tropical cyclones often affect the western North Pacific region. Between May and October annually, enormous flood damage is frequently caused by typhoons in Taiwan. This study adopted machine learning techniques to forecast the hourly wind speeds over offshore islands near Taiwan during tropical cyclones. To develop a highly reliable surface wind speed prediction technique, the four kernel-based support vector machines for regression (SVR) models, comprising radial basis function, linear, polynomial, and Pearson VII universal kernels were used. To ensure the accuracy of the SVR model, traditional regressions and the parametric wind representations, comprising the modified Rankine profile, Holland wind profile, and DeMaria wind profile were used to compare wind speed forecasts. The methodology was applied to two islands near Taiwan, Lanyu, and Pengjia Islets. The forecasting horizon ranged from 1 to 6 h. The results indicated that the Pearson VII SVR is the most precise of the kernel-based SVR models, regressions, and parametric wind representations. Additionally, Typhoons Nanmadol and Saola which made landfall over Taiwan during 2011 and 2012 were simulated and examined. The results showed that the Pearson VII SVR yielded more favorable results than did the regressions and Holland wind profile. In addition, we observed that Holland wind profile seems applicable to open ocean but unsuitable for areas affected by topographic effects, such as the Central Mountain Range of Taiwan.

  11. Response of dissolved oxygen and related marine ecological parameters to a tropical cyclone in the South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, Jingrou; Tang, Danling; Alpers, Werner; Wang, Sufen

    2014-04-01

    It is well known that tropical cyclones can cause upwelling, decrease of sea surface temperature, increase of chlorophyll-a (Chl-a) concentration and enhancement of primary production. But little is known about the response of dissolved oxygen (DO) concentration to a typhoon in the open ocean. This paper investigates the impact of a typhoon on DO concentration and related ecological parameters using in situ and remote sensing data. The in situ data were collected 1 week after the passage of the super-typhoon Nanmadol in the northern South China Sea in 2011. An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track. At these stations, maximum DO concentration was found at a depth of around 5 m and maximum Chl-a concentration at depths between 50 and 75 m. The layer of high DO concentration extends from the surface to a depth of 35 m and the concentrations stay almost constant down to this depth. Due to the passage of the typhoon, also a large sea level anomaly (21.6 cm) and a high value of Ekman pumping velocity (4.0 × 10-4 m s-1) are observed, indicating upwelling phenomenon. At the same time, also intrusion of Kuroshio waters in the form of a loop current into the South China Sea (SCS) was observed. We attribute the increase of DO concentration after the passage of the typhoon to three effects: (1) entrainment of oxygen from the air into the upper water layer and strong vertical mixing of the water body due to the typhoon winds, (2) upwelling of cold nutrient-rich water which stimulates photosynthesis of phytoplankton and thus the generation of oxygen, which also increases the DO concentration due to cold water since the solubility of oxygen increase with decreasing water temperature, and, possibly, (3) transport of DO enriched waters from the Western Pacific to the SCS via the intrusion of Kuroshio waters.

  12. Response of phytoplankton and dissolved oxygen and related marine ecological parameters to typhoon tropical cyclone in the oceans

    NASA Astrophysics Data System (ADS)

    Tang, DanLing

    Typhoons (tropical cyclones, or hurricanes) are strong wind events in the weather system, which influence the upper ocean dynamics and the ecosystem, in particular upwelling, water temperature, salinity, chlorophyll-a (Chl-a) concentration and primary production and fish abundances. But little is known about the response of dissolved oxygen (DO) concentration to a typhoon in the open ocean. This paper investigates the impact of a typhoon on DO concentration and related ecological parameters using in-situ and remote sensing data. The in-situ data were collected one week after the passage of the super-typhoon Nanmadol in the northern South China Sea in 2011. An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track. At these stations, maximum DO concentration was found at a depth of around 5 m and maximum Chl-a concentration at depths between 50 m and 75 m. The layer of high DO concentration extends from the surface to a depth of 35 m and the concentrations stay almost constant down to this depth. Due to the passage of the typhoon, also a large sea level anomaly (21.6 cm) and a high value of Ekman pumping velocity (4.0×10-4 m s-1) are observed, indicating upwelling phenomenon. At the same time, also intrusion of Kuroshio waters in the form of a loop current into the South China Sea (SCS) was observed. We attribute the increase of DO concentration after the passage of the typhoon to three effects:1) entrainment of oxygen from the air into the upper water layer and strong vertical mixing of the water body due to the typhoon winds, 2) upwelling of cold nutrient-rich water which stimulates photosynthesis of phytoplankton and thus the generation of oxygen, which also increases the DO concentration due to cold water since the solubility of oxygen increase with decreasing water temperature, and, possibly, 3) transport of DO enriched waters from the Western Pacific to the SCS via the intrusion of Kuroshio waters. After a series studies, taking full advantage of remote sensing technology and multiple satellite data, we proposed the theoretical system of “wind driven upper ocean- phytoplankton blooms -enhancing primary production”, and suggest an interdisciplinary “Remote Sensing Marine Ecology. Related paper can be fund from http://lingzis.51.net/journal%20article.htm.

  13. The impact of climate change on global tropical storm damages

    Microsoft Academic Search

    Robert Mendelsohn; Kerry Emanuel; Shun Chonabayashi

    2011-01-01

    This paper constructs an integrated assessment model of tropical cyclones in order to quantify the impact that climate change may have on tropical cyclone damages in countries around the world. The paper relies on a tropical cyclone generator in each oceanand several climate models to predict tropical cyclones with and without climate change. A damage model is constructed to compute

  14. A Numerical Study of the Impacts of Dry Air on Tropical Cyclone Formation: A Development Case and a Non-development Case

    NASA Astrophysics Data System (ADS)

    Fritz, C.; Wang, Z.

    2012-12-01

    The impacts of dry air on tropical cyclone formation are examined in the numerical model simulations of ex-Gaston (2010) and pre-Fay (2008). The former, a remnant low downgraded from a short-lived tropical cyclone, can be regarded as a non-developing system as it failed to redevelop, and the latter developed into a tropical cyclone despite lateral dry air entrainment and a transient upper-level dry air intrusion. Water vapor budget analysis suggests that the mean vertical moisture transport plays the dominant role in moistening the free atmosphere. Backward trajectory analysis and water budget analysis show that vertical transport of dry air from the middle and upper troposphere, where a well-defined wave pouch is absent, contributes to the mid-level drying near the pouch center in ex-Gaston. The mid-level drying suppresses deep convection, reduces moisture supply from the boundary layer, and contributes to the non-development of ex-Gaston. Three-dimensional trajectory analysis based on the numerical model simulation of Fay suggests that dry air entrained at the pouch periphery tends to stay off the pouch center due to the weak mid-level inflow or gets moistened along its path even if being wrapped into the wave pouch. Lateral entrainment in the middle troposphere thus does not suppress convection near the pouch center or prevent the development of Tropical Storm Fay. This study suggests that the upper troposphere is a weak spot of the wave pouch at the early formation stage and that the vertical transport is likely a more direct pathway for dry air to influence moist convection near the pouch center. Fig. 1 (a) 3 km relative humidity and storm relative streamlines for Gaston (2010) at 0800 UTC 05 September 2010 with a group of ensemble forward parcel trajectories (gray); (b) vertical cross section of RH along 17.5°N (contour intervals are set to 15%) and backward trajectories (gray) projected on the longitude-height plane. The box in (a) highlights a pocket of dry air near the pouch center. The line in (a) indicates the cross section location shown in (b). Particle trajectories and streamlines are both shown in a wave co-moving framework. The yellow dots indicate the initialization location of the ensemble trajectories.

  15. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment - Part 1: The role of the easterly wave critical layer

    NASA Astrophysics Data System (ADS)

    Montgomery, M. T.; Lussier, L. L., III; Moore, R. W.; Wang, Z.

    2010-10-01

    An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the surrounding base state is an easterly trade wind flow and the precursor disturbance to Typhoon Nuri is an easterly wave that originates in the ITCZ in the Central Pacific. This disturbance can be tracked more than 10 days prior to tropical storm formation. An overview of the field data is presented here using a newly proposed dynamical framework for tropical cyclone formation within the critical layer of an easterly wave. Despite propagating through a hostile environment ripe with strong vertical wind shear and relatively dry air, the easterly wave critical layer protects the proto-vortex and allows it to gestate until it reaches a more favorable environment. Within this protective "Kelvin cat's eye flow" located within the wave's critical layer existed a sweet spot, defined as the intersection between the wave trough and critical latitude, which is the preferred location for tropical cyclogenesis. Global Forecast System Final Analyses and IR satellite imagery, which shows convective bands wrapping around the sweet spot as genesis nears, confirm that this sweet spot is the location where Typhoon Nuri's dominant low-level circulation emerges. United States Air Force C130 and Naval Research Laboratory P3 research flights on 16 and 17 August collected flight-level, dropwindsonde, and Doppler radar data that allowed an evaluation of the dynamic and thermodynamic processes within the cat's eye circulation. The dropwindsonde analyses identifies the precursor easterly wave disturbance on 16 August and identifies an area of weak low-level cyclonic circulation on 17 August. Real-time forecasts were produced using operational global prediction model data to support scientific missions during TCS-08. These forecasts were found to be useful in flight planning discussions and predicted Typhoon Nuri's eventual genesis latitude within 1.5 degrees 72 h in advance.

  16. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment - Part 1: The role of the easterly wave critical layer

    NASA Astrophysics Data System (ADS)

    Montgomery, M. T.; Lussier, L. L., III; Moore, R. W.; Wang, Z.

    2009-09-01

    An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the surrounding base state flow was an easterly trade wind flow and the precursor disturbance to Typhoon Nuri was an easterly wave that originated in the ITCZ in the Central Pacific and can be tracked more than 10 days prior to tropical storm formation. An overview of the field data is presented here using a newly proposed dynamical framework for tropical cyclone formation within the critical layer of an easterly wave. Despite propagating through a hostile environment ripe with strong vertical wind shear and relatively dry air, the easterly wave critical layer protected the proto-vortex and allowed it to gestate until it reached a more favorable environment. Within this protective "Kelvin's cat's eye flow" located within the wave's critical layer existed a "sweet spot", defined as the intersection between the wave trough and critical latitude, which was the preferred location for tropical cyclogenesis. Global Forecast System Final Analyses and IR satellite imagery, which shows convective bands wrapping around the sweet spot as genesis nears, confirm that this sweet spot is the location where Typhoon Nuri's dominant low-level circulation emerges. United States Air Force C130 and Naval Research Laboratory P3 research flights on 16 and 17 August collected flight-level, dropwindsonde, and Doppler radar data that allowed an evaluation of the dynamic and thermodynamic processes within the cat's eye. The dropwindsonde analyses identified the precursor easterly wave disturbance on 16 August and identified an area of weak low-level cyclonic circulation on 17 August. During the TCS-08 experiment "real-time forecasts" were produced in real-time using operational global prediction model data to support scientific missions. These forecasts were found to be useful in flight planning discussions and predicted Nuri's genesis latitude within 1.5° 72 h in advance.

  17. Improving our Understanding of Atlantic Tropical Cyclones through Knowledge of the Saharan Air Layer: Hope or Hype?

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.; Shie, Chung-Lin

    2008-01-01

    The existence of the Saharan air layer (SAL), a layer of warm, dry, dusty air that frequently moves westward off of the Saharan desert of Africa and over the tropical Atlantic Ocean, has long been appreciated. As air moves over the desert, it is strongly heated from below, producing a very hot air mass at low levels. Because there is no moisture source over the Sahara, the rise in temperature causes a sharp drop in relative humidity, thus drying the air. In addition, the warm air produces a very strong jet of easterly flow in the middle troposphere called the African easterly jet that is thought to play a critical role in hurricane formation. In recent years, there has been an increased focus on the impact that the SAL has on the formation and evolution of hurricanes in the Atlantic. However, the nature of its impact remains unclear, with some researchers arguing that the SAL amplifies hurricane development and with others arguing that it inhibits it. The argument for positively influencing hurricane development is based upon the fact that the African easterly jet produces the waves that eventually form hurricanes and that it leads to rising motion south of the jet that favors the development of deep thunderstorm clouds. The potential negative impacts of the SAL include 1) low-level vertical wind shear associated with the African easterly jet; 2) warm SAL air aloft, which increases thermodynamic stability and suppresses cloud development; and 3) dry air, which produces cold downdrafts in precipitating regions, thereby removing energy needed for storm development. As part of this recent focus on the SAL and hurricanes (which motivated a 2006 NASA field experiment), there has been little emphasis on the SAL s potential positive influences and almost complete emphasis on its possible negative influences, almost to the point of claims that the SAL is the major suppressing influence on hurricanes in the Atlantic. Multiple NASA satellite data sets (TRMM, MODIS, and AIRS/AMSU) and National Centers for Environmental Prediction global analyses are used to characterize the SAL s properties and evolution in relation to developing hurricanes. The results show that storms generally form on the southern side of the jet, where favorable background rotation is high. The jet often helps to form the northern side of the storms and rarely moves over their inner cores, so jet-induced vertical wind shear does not appear to be a negative influence on developing storms. Warm SAL air is confined to regions north of the jet and generally does not impact the tropical cyclone precipitation south of the jet. Of the three proposed negative influences, dry air appears to be the key influence; however, the presence of dry SAL air is not a good indicator of whether a storm will weaken since many examples of intensifying storms surrounded by such dry air can be found. In addition, a global view of relative humidity shows moisture distributions in other ocean basins that are almost identical to the Atlantic. The dry zones correspond to regions of descending air on the eastern and equatorward sides of semi-permanent oceanic high pressure systems. Thus, the dry air over the Atlantic appears to be primarily a product of the large-scale flow, but with enhanced drying at low levels associated with the Sahara. As a result, we conclude that the SAL is not a major negative influence on hurricanes. It is just one of many possible influences and can be both positive and negative.

  18. Design of Wind Turbines in an Area with Tropical Cyclones Niels-Erik Clausen, niels-erik.clausen@risoe.dk, Sren Ott, Niels-Jacob Tarp-Johansen, Per Nrgrd and

    E-print Network

    Design of Wind Turbines in an Area with Tropical Cyclones Niels-Erik Clausen, niels and cost of wind turbines is influenced by a combination of fatigue and extreme loads and the applied design codes. In general wind turbines are designed for 20 years of operation using design standards

  19. Improving Tropical Cyclogenesis Statistical Model Forecasts through the Application of a Neural Network Classifier

    E-print Network

    Hennon, Christopher C.

    Network Classifier CHRISTOPHER C. HENNON Department of Atmospheric Sciences, University of North Carolina (Manuscript received 23 March 2004, in final form 22 May 2005) ABSTRACT A binary neural network classifier forecasts for genesis at 6-h intervals. Results consistently show that the neural network classifier

  20. Extremely high-energy wave deposits inside the Great Barrier Reef, Australia: determining the cause—tsunami or tropical cyclone

    Microsoft Academic Search

    Jonathan Nott

    1997-01-01

    A hydrodynamic approach is used to determine whether tsunami- or cyclone-generated waves were responsible for the deposition of fields of well-imbricated rock boulders (up to 290 tonnes) along the coast of Cairns inside the Great Barrier Reef, Australia. Calculations of the overturning moments show that only tsunami are capable of moving such large boulders in this environment. It is hypothesised

  1. On the Use of Two-Dimensional Incompressible Flow to Study Secondary Eyewall Formation in Tropical Cyclones

    E-print Network

    Miami, University of

    Cyclones YUMIN MOON, DAVID S. NOLAN, AND MOHAMED ISKANDARANI Rosenstiel School of Marine and Atmospheric; Nong and Emanuel 2003; Terwey and Montgomery 2008; Judt and Chen 2010), and a number of them use two parameters. In the parameter space considered by K04 Corresponding author address: Yumin Moon, University

  2. Two millennia of tropical cyclone-induced mud layers in a northern Yucatán stalagmite: Multiple overlapping climatic hazards during the Maya Terminal Classic "megadroughts"

    NASA Astrophysics Data System (ADS)

    Frappier, Amy Benoit; Pyburn, James; Pinkey-Drobnis, Aurora D.; Wang, Xianfeng; Corbett, D. Reide; Dahlin, Bruce H.

    2014-07-01

    An annually laminated stalagmite from the northern Yucatán Peninsula contains mud layers from 256 cave flooding events over 2240 years. This new conservative proxy for paleotempestology recorded cave flooding events with a recurrence interval of 8.3 years during the twentieth century, with the greatest frequency during the twentieth century and the least frequent during the seventeenth century. Tropical cyclone (TC) events are unlikely to flood the cave during drought when the water table is depressed. Applying TC masking to the Chaac paleorainfall reconstruction suggests that the severity of the Maya "megadroughts" was underestimated. Without a high-resolution radiometric geochronology of individual local TC events, speleothem isotope records cannot resolve whether the Terminal Classic Period in the northern Maya Lowlands was punctuated by several brief drought breaks with normal TCs, or whether the region was very dry and peppered by unusually severe and frequent hurricane seasons.

  3. Tropical Cyclone Gonu: Number of Patients and Pattern of Illnesses in the Primary Health Centers in A’Seeb Area, Muscat, Sultanate of Oman

    PubMed Central

    Alhinai, Mustafa Y.

    2011-01-01

    Objectives On June 6th 2007, a tropical Cyclone Gonu striked the coastline of Oman. The purpose of this study is to compare number of patients and pattern of illnesses between disaster (June 2007) and peace times (June 2006/2008). Methods Descriptive comparative analysis of all patients who visited primary health centers in Wilayat A’Seeb during the index days. Electronic database collected from the Health Centers (HC) were grouped into four groups; infection-related, trauma-related, acute non trauma-related, and miscellaneous group. Data were analyzed to find difference of patient influx and disease patterns between disaster and peace times. Results HC visits during the index days decreased from 9006 in 2006 to 8687 in 2007 then increased to 8786 in 2008. Neither between years variation nor between disaster and peace times difference was found to be statistically significant. The proportion of patient visited the HC due to infection-related illnesses changed from 30% in 2006, 31% in 2007, and 24% in 2008 (p<0.0001). The proportion of patients visited the HC due to trauma-related illnesses had changed from 4% in 2006, to 6.7% in 2007, and to 4.4% in 2008. (p<0.0001). Proportions for acute non trauma-related visits were 27% in 2006, 24% in 2007, and 23% in 2008 (p<0.0001). Miscellaneous group accounted for 38% in 2006, 37% in 2007, and 47% in 2008 (p<0.0001). Conclusion Tropical Cyclone Gonu caused statistically significant increase in percentages of infectious and trauma-related visits. The overall ratios of total visits did not differ from peace times. PMID:22043424

  4. Louisiana Natural Disasters and Ecological Forecasting: Assessment of Tropical Cyclone Induced Transgression of the Chandeleur Islands for Restoration and Wildlife Management

    NASA Astrophysics Data System (ADS)

    Reahard, R. R.; Mitchell, B. S.; Childs, L. M.; Billiot, A.; Brown, T.

    2009-12-01

    The Chandeleur Islands are the first line of defense against tropical storms and hurricanes for coastal Louisiana. They provide habitats for bird species and are a national wildlife refuge; however, they are eroding and transgressing at an alarming rate. In 1998, Hurricane Georges caused severe damage to the chain, prompting restoration and monitoring efforts by both Federal and State agencies. Since then, storm events have steadily diminished the condition of the islands. Quantification of shoreline erosion, vegetation, and land loss, from 1979 to 2009, was calculated through the analysis of imagery from Landsat 2-4 Multispectral Scanner, Landsat 4 & 5 Thematic Mapper, and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensors. QuickBird imagery was used to validate the accuracy of these results. In addition, this study presents an application of Moderate Resolution Imaging Spectroradiometer (MODIS) data to assist in tracking the landward migration of the Chandeleur Islands. The use of near infrared reflectance calculated from MOD09 surface reflectance data from 2000 to 2008 was analyzed using the Time Series Product Tool. The scope of this project includes not only assessments of the tropical cyclonic events during this time period, but also the effects of tides, winds, and cold fronts on the spatial extent of the islands. Partnering organizations, such as the Pontchartrain Institute for Environmental Sciences, will utilize those results in an effort to better monitor and address the continual change of the Chandeleur Islands.

  5. Dynamics and Predictability of Tropical Cyclone Genesis Evaluated through a Coupled EnKF and 4DVar Data Assimilation Method during GRIP and PREDICT 2010.

    NASA Astrophysics Data System (ADS)

    Reyes, A.; Jenkins, G. S.; Poterjoy, J.; Zhang, F.

    2014-12-01

    The genesis of Hurricane Karl (2010) and Tropical Storm Mathew (2010) are examined and compared using a coupled ensemble Kalman filter and four-dimension variational data assimilation method (E4DVar) to assimilate conventional and field campaign observations. This research makes use of dropsonde and sounding observations, which were collected during both the Genesis and Rapid Intensification Processes (GRIP) and the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) field campaigns. E4DVar uses a mix of climatological and flow-dependent background error covariance obtained from ensemble forecasts together with the tangent linear model and its adjoint to perform the four-dimensional data assimilation. As a result, E4DVar analyses are able to capture multi-scale features of the developing disturbances accurately, such as the evolving thermodynamic and kinematic structure of pre-genesis Karl and Mathew. Preliminary diagnostics shows that the genesis of both storms followed a bottom-up process with several mesoscale convective vorticies (MCVs) observed in the pre-genesis stages. To determine the role of these MCVs and to better understand the initial development of the surface cyclone, a two-dimensional spectral decomposition and filtering of model variables, together with a vorticity budget, are performed on high-resolution (1.5 km) simulations of both systems.

  6. Experimental Dynamical Seasonal Forecasts of Tropical Cyclone Activity at IRI SUZANA J. CAMARGO AND ANTHONY G. BARNSTON

    E-print Network

    Camargo, Suzana J.

    University (Gray et al. 1993; Klotzbach 2007a), the typhoon activity forecasts of the City Univer- sity of Hong Kong (Chan et al. 1998, 2001), and Tropical Storm Risk (Saunders and Lea 2004). A review of TC

  7. Global representation of tropical cyclone-induced ocean thermal changes using Argo data - Part 2: Estimating air-sea heat fluxes and ocean heat content changes

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Zhu, J.; Sriver, R. L.

    2014-12-01

    We use Argo temperature data to examine changes in ocean heat content (OHC) and air-sea heat fluxes induced by tropical cyclones (TC)s on a global scale. A footprint technique that analyzes the vertical structure of cross-track thermal responses along all storm tracks during the period 2004-2012 is utilized (see part I). We find that TCs are responsible for 1.87 PW (11.05 W m-2 when averaging over the global ocean basin) of heat transfer annually from the global ocean to the atmosphere during storm passage (0-3 days) on a global scale. Of this total, 1.05 ± 0.20 PW (4.80 ± 0.85 W m-2) is caused by Tropical storms/Tropical depressions (TS/TD) and 0.82 ± 0.21 PW (6.25 ± 1.5 W m-2) is caused by hurricanes. Our findings indicate that ocean heat loss by TCs may be a substantial missing piece of the global ocean heat budget. Net changes in OHC after storm passage is estimated by analyzing the temperature anomalies during wake recovery following storm events (4-20 days after storm passage) relative to pre-storm conditions. Results indicate the global ocean experiences a 0.75 ± 0.25 PW (5.98 ± 2.1W m-2) net heat gain annually for hurricanes. In contrast, under TS/TD conditions, ocean experiences 0.41 ± 0.21 PW (1.90 ± 0.96 W m-2) net ocean heat loss, suggesting the overall oceanic thermal response is particularly sensitive to the intensity of the event. The net ocean heat uptake caused by all storms is 0.34 PW.

  8. Anatomy and evolution of a cyclonic mesoscale eddy observed in the northeastern Pacific tropical-subtropical transition zone

    NASA Astrophysics Data System (ADS)

    Kurczyn, J. A.; Beier, E.; Lavín, M. F.; Chaigneau, A.; Godínez, V. M.

    2013-11-01

    In November 2005 off Cabo Corrientes, a cyclonic eddy was sampled from (i) remotely sensed data of sea level anomaly, near-surface wind, chlorophyll-a concentration and sea surface temperature and (ii) direct observations from a lowered Acoustic Doppler profiler, and a conductivity, temperature, and depth sensor. The sea level anomaly data set and an automated eddy detection method showed that this vortex formed near the Mexican coast and traveled westward/northwestward, ˜1000 km into the open ocean for ˜8 months. Surface winds and currents indicated that the cyclone was generated during a coastal upwelling event that occurred simultaneously with an equatorward flow located close to the coast. During its growing phase, the eddy extended from the surface to 750 m depth and mixed the water column in the first ˜100 m, showing an eastward shift of the eddy axis toward the sea surface of 1.5° of longitude, that generated a southward meridional heat transport in the upper layers. Integrated in the vertical, this heat transport accounted for a total of -105 × 1012 W, within the region of the eddy. The estimation of the available heat and salt anomaly contents revealed that the eddy transported relatively cold, salty, and anoxic waters associated with the Subtropical Subsurface water mass. While traveling offshore, the cyclonic eddy also exhibited relatively higher chlorophyll a concentrations at the sea surface than its surroundings. Comparison of some surface properties estimated from satellite and in situ data showed that satellite data tend to underestimate its amplitude and orbital geostrophic velocity.

  9. Idealized numerical experiments associated with the intensity and rapid intensification of stationary tropical-cyclone-like vortex and its relation to initial sea-surface temperature and vortex-induced sea-surface cooling

    Microsoft Academic Search

    Akiyoshi Wada

    2009-01-01

    Idealized numerical experiments were performed using a nonhydrostatic atmospheric model coupled with a slab mixed-layer ocean model with a horizontal grid spacing of 2 km in order to investigate the roles of initial sea-surface temperature (SST) and vortex-induced sea-surface cooling (SSC) in the intensity and intensification of a stationary idealized tropical-cyclone-like vortex. Numerical experiment results indicate that the coupled model

  10. Identification of Storm Surge Vulnerable Areas in the Philippines Through Simulations of Typhoon Haiyan-Induced Storm Surge Using Tracks of Historical Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Lapidez, John Phillip; Suarez, John Kenneth; Tablazon, Judd; Dasallas, Lea; Gonzalo, Lia Anne; Santiago, Joy; Cabacaba, Krichi May; Ramos, Michael Marie Angelo; Mahar Francisco Lagmay, Alfredo; Malano, Vicente

    2014-05-01

    Super Typhoon Haiyan entered the Philippine Area of Responsibility (PAR) 07 November 2013, causing tremendous damage to infrastructure and loss of lives mainly due to the typhoon's storm surge and strong winds. Storm surges up to a height of 7 meters were reported in the hardest hit areas. The threat imposed by this kind of natural calamity compelled researchers of the Nationwide Operational Assessment of Hazards, the flagship disaster mitigation program of the Department of Science and Technology, Government of the Philippines, to undertake a study to determine the vulnerability of all Philippine coastal communities to storm surges of the same magnitude as those generated by Haiyan. This study calculates the maximum probable storm surge height for every coastal locality by running simulations of Haiyan-type conditions but with tracks of tropical cyclones that entered PAR from 1948-2013. DOST-Project NOAH used the Japan Meteorological Agency (JMA) Storm Surge Model, a numerical code that simulates and predicts storm surges spawned by tropical cyclones. Input parameters for the storm surge model include bathymetric data, storm track, central atmospheric pressure, and maximum wind speed. The simulations were made using Haiyan's pressure and wind speed as the forcing parameters. The simulated storm surge height values were added to the maximum tide level obtained from WXTide, software that contains a catalogue of worldwide astronomical tides, to come up with storm tide levels. The resulting water level was used as input to FLO-2D to generate the storm tide inundation maps. One product of this study is a list of the most vulnerable coastal areas that can be used as basis for choosing priority sites for further studies to implement appropriate site-specific solutions. Another product is the storm tide inundation maps that the local government units can use to develop a Risk-Sensitive Land Use Plan for identifying appropriate areas to build residential buildings, evacuation sites, and other critical facilities and lifelines. The maps can also be used to develop a disaster response plan and evacuation scheme.

  11. PUBLISHED ONLINE: 12 FEBRUARY 2012 | DOI: 10.1038/NCLIMATE1410 Global trends in tropical cyclone risk

    E-print Network

    Kossin, James P.

    exposed and their vulnerability, as well as the frequency and intensity of storms. How will the cumulative of the world and affect nearly all tropical areas (Fig. 1). They are associated with extreme winds, torrential rains triggering floods and/or landslides, high waves and damaging storm surges leading to extensive

  12. The Mechanical Energy Input to the Ocean Induced by Tropical Cyclones LING LING LIU AND WEI WANG

    E-print Network

    Huang, Rui Xin

    in a Chinese tropical forest Jiajia Liu a,b , Tan Yunhong c , J.W. Ferry Slik d, a Community Ecology and compiled data of the maximum height, leaf area, seed mass and wood density of 334 tree species in 500 the topographical gradient. This change was accompanied by increasing community average seed mass and wood density

  13. Tracking and Verification of East Atlantic Tropical Cyclone Genesis in the NCEP Global Ensemble: Case Studies during the NASA African

    E-print Network

    Pu, Zhaoxia

    : Case Studies during the NASA African Monsoon Multidisciplinary Analyses ANDREW D. SNYDER AND ZHAOXIA PU to a genesis time defined to be the first designation of the tropical depression from the National Hurricane and Kalnay 1997; Buizza et al. 2005; Wei et al. 2008; Reynolds et al. 2008). During the hurricane season

  14. Impact of Secondary Eyewall Heating on Tropical Cyclone Intensity Change* XIAQIONG ZHOU, BIN WANG, XUYANG GE, AND TIM LI

    E-print Network

    Wang, Bin

    weakening are compared using the Tropical Rainfall Measuring Mission (TRMM) 2A12 and 2A25 data. It is found that the secondary eyewalls with a stratiform-type heating profile show a marked weakening, while those TCs convection, the latent heat released in the outer eyewall and moat region can better sustain storm intensity

  15. On the Characterization of Rainfall Associated with U.S. Landfalling North Atlantic Tropical Cyclones Based on Satellite Data and Numerical Weather Prediction Outputs

    NASA Astrophysics Data System (ADS)

    Luitel, B. N.; Villarini, G.; Vecchi, G. A.

    2014-12-01

    When we talk about tropical cyclones (TCs), the first things that come to mind are strong winds and storm surge affecting the coastal areas. However, according to the Federal Emergency Management Agency (FEMA) 59% of the deaths caused by TCs since 1970 is due to fresh water flooding. Heavy rainfall associated with TCs accounts for 13% of heavy rainfall events nationwide for the June-October months, with this percentage being much higher if the focus is on the eastern and southern United States. This study focuses on the evaluation of precipitation associated with the North Atlantic TCs that affected the continental United States over the period 2007 - 2012. We evaluate the rainfall associated with these TCs using four satellite based rainfall products: Tropical Rainfall Measuring Mission - Multi-satellite Precipitation Analysis (TMPA; both real-time and research version); Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN); Climate Prediction Center (CPC) MORPHing technique (CMORPH). As a reference data we use gridded rainfall provided by CPC (Daily US Unified Gauge-Based Analysis of Precipitation). Rainfall fields from each of these satellite products are compared to the reference data, providing valuable information about the realism of these products in reproducing the rainfall associated with TCs affecting the continental United States. In addition to the satellite products, we evaluate the forecasted rainfall produced by five state-of-the-art numerical weather prediction (NWP) models: European Centre for Medium-Range Weather Forecasts (ECMWF), UK Met Office (UKMO), National Centers for Environmental Prediction (NCEP), China Meteorological Administration (CMA), and Canadian Meteorological Center (CMC). The skill of these models in reproducing TC rainfall is quantified for different lead times, and discussed in light of the performance of the satellite products.

  16. Increased threat of island endemic tree’s extirpation via invasion-induced decline of intrinsic resistance to recurring tropical cyclones

    PubMed Central

    Marler, Thomas E.

    2013-01-01

    Cycas micronesica populations in Guam have been threatened by the invasion of the armored scale Aulacaspis yasumatsui. I integrate four factors that illuminate an acute need for intervention to reduce an unprecedented threat caused by the invasion. First, mechanical failure of healthy C. micronesica trees during catastrophic winds is rare because of the cycad tree’s unique pachycaulis stem design. Second, tree-winching and three-point bend stress tests revealed the natural resistance to damage from tropical cyclones has been compromised by the chronic feeding of this homopteran pest. Third, no typhoon event has occurred since the arthropod’s invasion and its spread in the year 2005 to actually test extent of mechanical failure for the unhealthy remaining trees. Fourth, historical records indicate the probability that Guam will experience typhoon force winds is 0.51 in three years and 0.91 in 10 y. These four factors integrate to predict the next typhoon may eliminate the surviving C. micronesica trees and stewardship of this declining population requires intervention to counter this prediction. PMID:23802037

  17. Cholera Outbreak Linked with Lack of Safe Water Supply Following a Tropical Cyclone in Pondicherry, India, 2012

    PubMed Central

    Fredrick, Tony; Ponnaiah, Manickam; Murhekar, Manoj V.; David, Joseph K.; Vadivoo, Selvaraj; Joshua, Vasna

    2015-01-01

    ABSTRACT In the aftermath of a severe cyclonic storm on 7 January 2012, a cluster of acute diarrhoea cases was reported from two localities in Pondicherry, Southern India. We investigated the outbreak to identify causes and recommend control measures. We defined a case as occurrence of diarrhoea of more than three loose stools per day with or without vomiting in a resident of affected areas during 6-18 January 2012. We used active (door-to-door survey) and stimulated passive (healthy facility-based) surveillance to identify cases. We described the outbreak by time, place, and person. We compared the case-patients with up to three controls without any apparent signs and symptoms of diarrhoea and matched for age, gender, and neighbourhood. We calculated matched odds ratio (MOR), 95% confidence intervals (CI), and population attributable fractions (PAF). We collected rectal swabs and water samples for laboratory diagnosis and tested water samples for microbiological quality. We identified 921 cases and one death among 8,367 residents (attack rate: 11%, case-fatality: 0.1%). The attack rate was the highest among persons of 50 years and above (14%) and females (12%). The outbreak started on 6 January and peaked on the 9th and lasted till 14 January. Cases were clustered around two major leakages in water supply system. Nine of the 16 stool samples yielded V. cholerae O1 Ogawa. We identified that consumption of water from the public distribution system (MOR=37, 95% CI 4.9-285, PAF: 97%), drinking unboiled water (MOR=35, 95% CI 4.5-269, PAF: 97%), and a common latrine used by two or more households (MOR=2.7, 95% CI 1.3-5.6) were independently associated with cholera. Epidemiological evidence suggested that this outbreak was due to ingestion of water contaminated by drainage following rains during cyclone. We recommended repair of the water supply lines, cleaning-up of the drains, handwashing, and drinking of boiled water. PMID:25995719

  18. Cholera outbreak linked with lack of safe water supply following a tropical cyclone in pondicherry, India, 2012.

    PubMed

    Fredrick, Tony; Ponnaiah, Manickam; Murhekar, Manoj V; Jayaraman, Yuvaraj; David, Joseph K; Vadivoo, Selvaraj; Joshua, Vasna

    2015-03-01

    In the aftermath of a severe cyclonic storm on 7 January 2012, a cluster of acute diarrhoea cases was reported from two localities in Pondicherry, Southern India. We investigated the outbreak to identify causes and recommend control measures. We defined a case as occurrence of diarrhoea of more than three loose stools per day with or without vomiting in a resident of affected areas during 6-18 January 2012. We used active (door-to-door survey) and stimulated passive (healthy facility-based) surveillance to identify cases. We described the outbreak by time, place, and person. We compared the case-patients with up to three controls without any apparent signs and symptoms of diarrhoea and matched for age, gender, and neighbourhood. We calculated matched odds ratio (MOR), 95% confidence intervals (CI), and population attributable fractions (PAF). We collected rectal swabs and water samples for laboratory diagnosis and tested water samples for microbiological quality. We identified 921 cases and one death among 8,367 residents (attack rate: 11%, case-fatality: 0.1%). The attack rate was the highest among persons of 50 years and above (14%) and females (12%). The outbreak started on 6 January and peaked on the 9th and lasted till 14 January. Cases were clustered around two major leakages in water supply system. Nine of the 16 stool samples yielded V. cholerae O1 Ogawa. We identified that consumption of water from the public distribution system (MOR=37, 95% CI 4.9-285, PAF: 97%), drinking unboiled water (MOR=35, 95% CI 4.5-269, PAF: 97%), and a common latrine used by two or more households (MOR=2.7, 95% CI 1.3-5.6) were independently associated with cholera. Epidemiological evidence suggested that this outbreak was due to ingestion of water contaminated by drainage following rains during cyclone. We recommended repair of the water supply lines, cleaning-up of the drains, handwashing, and drinking of boiled water. PMID:25995719

  19. Cyclone Monty

    Atmospheric Science Data Center

    2013-04-16

    ... On February 29, Monty was upgraded to category 4 cyclone status. After traveling inland about 300 kilometers to the south, the ... at different view angles. The height retrievals are at this stage uncorrected for the effects of the high winds associated with cyclone ...

  20. An air pollution episode and its formation mechanism during the tropical cyclone Nuri's landfall in a coastal city of south China

    NASA Astrophysics Data System (ADS)

    Yang, John Xun; Lau, Alexis Kai Hon; Fung, Jimmy Chi Hung; Zhou, Wen; Wenig, Mark

    2012-07-01

    In this work we investigated an air pollution episode during the landfall process of a tropical cyclone (TC) in Hong Kong. TCs affect air condition and account for most air pollution episodes in summer of this region. In August 2008, TC Nuri made direct landfall in Hong Kong. Before its landfall, an air pollution episode occurred, where major pollutants like SO2 and PM10 increased eight and six times higher respectively. Rather than using single measurement method, we combined ground air sampling, lidar, sunphotometer and satellite lidar CALIPSO with focus on aerosol to study the episode mechanism, and some new phenomena were found. During the episode, it was found that heavy inland aerosol plumes existed in areas larger than urbanized regions and were elevated vertically and transported southward. During episode, planetary boundary layer (PBL) expansion and height increase were observed, which is different from previous reported PBL compression and height decrease. While vertical subsidence and horizontal stagnation and consequently local aerosol accumulation were attributed as the main episode cause in previous cases, our observation showed that transported aerosols dominated in this TC landfall event. This can be further confirmed by examining aerosol chemical composition, size distribution and single scattering albedo, where transported related species showed significantly change and local indicators remained relatively stable. Invigorated cloud droplets were found on the boundary layer top upon aerosol elevation. The results indicate that site difference and TC tracks should be considered for analyzing episode formation mechanism. They can cause difference in the strength of vertical subsidence and horizontal advection and affect pollution flow direction, which subsequently results in different pollution formation processes.

  1. Antecedent mid-tropospheric frontogenesis caused by the interaction between a tropical cyclone and midlatitude trough: a case study of Typhoon Rusa (2002)

    NASA Astrophysics Data System (ADS)

    Baek, Eun-Hyuk; Lim, Gyu-Ho; Kim, Joo-Hong; Kug, Jong-Seong

    2014-10-01

    This study examines antecedent mid-tropospheric frontogenesis (AMF) resulting from the interaction between Typhoon Rusa (2002) and a midlatitude trough over the Korean Peninsula. In this event, the AMF contributed to the first peak in the time series of rainfall in Gangneung (37.75°N, 128.90°E), occurring about 12 h before the time of the extratropical transition (ET) process of the tropical cyclone (TC). Using observations and high-resolution model outputs, we showed that the AMF contributed to the antecedent rainfall in Gangneung during the first rainfall period when Gangneung was located outside of Rusa's sphere of direct influence. A Weather Research Forecasting (WRF) model experiment was conducted to diagnose the frontogenetical features and associated precipitation processes in detail. The experiment revealed that the AMF was mainly forced by the horizontal deformation forcing (HDF). The direction of the HDF was oriented from southwest to northeast in the middle part of the peninsula. The HDF increased positively due to the confluence of the southeasterlies from the TC and the northwesterlies emanating from the midlatitude trough. The experiment also suggested that the mid-tropospheric moisture originated from the subtropical ocean and deposited into the frontal region by the southerlies on the eastern periphery of the TC, which enhanced the convergence of moisture flux in the frontal region during the first rainfall period. The thermally direct circulation associated with the AMF lead to the mid-tropospheric saturation, which enhanced the precipitation of the first rainfall event together with the orographically forced convection at the low level above Gangneung.

  2. On the Sizes of the North Atlantic Basin Tropical Cyclones Based on 34- and 64-kt Wind Radii Data, 2004-2013

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2014-01-01

    At end of the 2012 hurricane season the National Hurricane Center retired the original HURDAT dataset and replaced it with the newer version HURDAT2, which reformatted the original data and included additional information, in particular, estimates of the 34-, 50, and 64-kt wind radii for the interval 2004-2013. During the brief 10-year interval, some 164 tropical cyclones are noted to have formed in the North Atlantic basin, with 77 becoming hurricanes. Hurricane Sandy (2012) stands out as being the largest individual storm that occurred in the North Atlantic basin during the 2004 -2013 timeframe, both in terms of its 34- and 64-kt wind radii and wind areas, having maximum 34- and 64-kt wind radii, maximum wind areas, and average wind areas each more than 2 standard deviations larger than the corresponding means. In terms of the largest yearly total 34-kt wind area (i.e., the sum of all individual storm 34-kt wind areas during the year), the year 2010 stands out as being the largest (about 423 × 10(exp 6) nmi(exp 2)), compared to the mean of about 174 × 10(exp 6) nmi(exp 2)), surpassing the year 2005 (353 x 10(exp 6) nmi(exp 2)) that had the largest number of individual storms (28). However, in terms of the largest yearly total 64-kt wind area, the year 2005 was the largest (about 9 × 10(exp 6) nmi(exp 2)), compared to the mean of about 3 × 106 nmi(exp 2)). Interesting is that the ratio of total 64-kt wind area to total 34-kt wind area has decreased over time, from 0.034 in 2004 to 0.008 in 2013.

  3. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment - Part 3: Dynamics of low-level spin-up during the genesis

    NASA Astrophysics Data System (ADS)

    Lussier, L. L., III; Montgomery, M. T.; Bell, M. M.

    2013-10-01

    Aircraft reconnaissance data collected during the Tropical Cyclone Structure 2008 field campaign are used to examine further kinematical, dynamical and thermodynamical aspects of the genesis of Typhoon Nuri. Data from the first two missions into the pre-Nuri disturbance document the transition from a tropical wave to a tropical depression. Dropwindsonde-derived tangential wind profiles at several radii from the low-level circulation center indicate that the magnitude of low-level circulation increases and that the corresponding tangential velocity maximum moves inward from the first to second reconnaissance mission. To compliment these findings, a three-dimensional variational analysis incorporating both dropwindsonde and aircraft Doppler radar data is conducted. These data are used to perform circulation tendency calculations at multiple distances from the low-level circulation center. The results demonstrate a net spin-up of the system-scale circulation in the low-levels near the center and in the outer regions of the recirculating Kelvin cat's eye circulation. In these regions, the spin-up tendency due to the influx of cyclonic absolute vorticity exceeds the frictional spin-down tendency for both Nuri missions. The system-scale spin up is found to be accompanied by areas of low-level vorticity concentration through vortex-tube stretching associated with cumulus convection. The areal coverage and intensity of these high-vorticity regions increase between the first and second Nuri missions. The findings of this study are consistent in some respects to the Nuri observational analysis carried out by Raymond and Lopez (2011), but differ in their suggested key result and related scientific implication that the pre-Nuri disturbance was spinning down on the first day of observations. The findings herein strongly support a recent tropical cyclogenesis model positing that the Kelvin cat's eye circulation of the parent wave-like disturbance provides a favorable environment for convective-vorticity organization and low-level spin-up on the mesoscale.

  4. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment - Part 3: Dynamics of low-level spin-up during the genesis

    NASA Astrophysics Data System (ADS)

    Lussier, L. L., III; Montgomery, M. T.; Bell, M. M.

    2014-08-01

    Aircraft reconnaissance data collected during the Tropical Cyclone Structure 2008 field campaign are used to examine further kinematical, dynamical, and thermodynamical aspects of the genesis of Typhoon Nuri. Data from the first two missions into the pre-Nuri disturbance document the transition from a tropical wave to a tropical depression. Dropwindsonde-derived tangential wind profiles at several radii from the low-level circulation center indicate that the magnitude of low-level circulation increases and that the corresponding tangential velocity maximum moves inward from the first to second reconnaissance mission. To compliment these findings, a three-dimensional variational analysis incorporating both dropwindsonde and aircraft Doppler radar data is conducted. These data are used to perform circulation tendency calculations at multiple distances from the low-level circulation center. The results demonstrate a net spin-up of the system-scale circulation in the low levels near the center and in the outer regions of the recirculating Kelvin cat's eye circulation. In these regions, the spin-up tendency due to the influx of cyclonic absolute vorticity exceeds the frictional spin-down tendency for both Nuri missions. The system-scale spin-up is found to be accompanied by areas of low-level vorticity concentration through vortex-tube stretching associated with cumulus convection. The areal coverage and intensity of these high-vorticity regions increase between the first and second Nuri missions. The findings of this study are consistent in some respects to the Nuri observational analysis carried out by Raymond and López-Carrillo (2011), but differ in their suggested key results and related scientific implications that the pre-Nuri disturbance was spinning down in the planetary boundary layer on the first day of observations. The findings herein strongly support a recent tropical cyclogenesis model positing that the Kelvin cat's eye circulation of the parent wave-like disturbance provides a favorable environment for convective vorticity organization and low-level spin-up on the mesoscale.

  5. Tropical Prediction Center: National Hurricane Center

    NSDL National Science Digital Library

    The National Hurricane Center contains news of active tropical systems; a hurricane awareness section about the hazards of hurricanes and what you can do to help protect yourself, your family, and your property; links to regional tropical cyclone centers; tropical weather outlooks, marine forecasts, and Sea Surface Temperature analyses; blank hurricane tracking charts; and current season summaries and tropical cyclone reports including synoptic history, meteorological statistics, casualties and damages, and the post-analysis best track.

  6. Associating extreme precipitation events to parent cyclones in gridded data

    NASA Astrophysics Data System (ADS)

    Rhodes, Ruari; Shaffrey, Len; Gray, Sue

    2015-04-01

    When analysing the relationship of regional precipitation to its parent cyclone, it is insufficient to consider the cyclone's region of influence as a fixed radius from the centre due to the irregular shape of rain bands. A new method is therefore presented which allows the use of objective feature tracking data in the analysis of regional precipitation. Utilising the spatial extent of precipitation in gridded datasets, the most appropriate cyclone(s) may be associated with regional precipitation events. This method is applied in the context of an analysis of the influence of clustering and stalling of extra-tropical cyclones in the North Atlantic on total precipitation accumulations over England and Wales. Cyclone counts and residence times are presented for historical records (ERA-Interim) and future projections (HadGEM2-ES) of extreme (> 98th percentile) precipitation accumulations over England and Wales, for accumulation periods ranging from one day to one month.

  7. Terr. Atmos. Ocean. Sci., Vol. 18, No. 4, 805-825, October 2007 Climate Prediction of Tropical Cyclone Activity in the Vicinity

    E-print Network

    Hawai'i at Manoa, University of

    effects of potential flooding, storm surges, and high winds resulting from typhoons. W. Gray and his.g., the annual number of typhoons and the annual number of tropical storms and typhoons). The informative results June through October, when typhoons are most active in the study domain. The model is based

  8. Louisiana Natural Disasters and Ecological Forecasting: Assessment of Tropical Cyclone Induced Transgression of the Chandeleur Islands for Restoration and Wildlife Management

    Microsoft Academic Search

    R. R. Reahard; B. S. Mitchell; L. M. Childs; A. Billiot; T. Brown

    2009-01-01

    The Chandeleur Islands are the first line of defense against tropical storms and hurricanes for coastal Louisiana. They provide habitats for bird species and are a national wildlife refuge; however, they are eroding and transgressing at an alarming rate. In 1998, Hurricane Georges caused severe damage to the chain, prompting restoration and monitoring efforts by both Federal and State agencies.

  9. Conceptual Models of Tropical Waves

    NSDL National Science Digital Library

    2014-09-14

    Tropical waves are prolific rainfall producers that sometimes form tropical cyclones. Conceptual models of tropical waves are used to help learners understand the dynamical characteristics and evolution of tropical waves. Users will learn about the vertical and horizontal structure of tropical waves and the typical weather changes that accompany the passage of a tropical wave. Four different methods of tracking tropical waves are also provided. The Webcast is presented by Mr. Horace Burton and Mr. Selvin Burton of the Caribbean Institute for Meteorology and Hydrology under the auspices of the MeteoForum Project.

  10. Assessing the impact of cyclones in the coastal zone of Bangladesh

    NASA Astrophysics Data System (ADS)

    Wolf, Judith; Bricheno, Lucy; Chowdury, Shahad; Rahman, Munsur; Ghosh, Tuhin; Kay, Susan; Caesar, John

    2014-05-01

    We review the state of knowledge regarding tropical cyclones and their impacts on coastal ecosystems, as well as the livelihood and health of the coastal communities, under the present and future climate, with application to the coastal zone of Bangladesh. This region is particularly vulnerable to tropical cyclones as it is very low-lying and densely populated. Cyclones cause damage due to the high wind speed and also the ensuing storm surge, which causes inundation and salinity intrusion into agricultural land and contaminates fresh water. The world's largest mangrove forest, the Sundarbans, protects the coast of the Brahmaputra-Ganges-Meghna (BGM) delta from these cyclonic storms but mangroves are themselves vulnerable to cyclone damage, as in 2007 when ~36% of the mangrove area was severely damaged leading to further losses of livelihood. We apply an idealised cyclone model and use the winds and pressures from this model to drive a storm surge model in the Bay of Bengal, in order to examine the impact of the intensity, track speed and landfall of the cyclones in terms of surge and inundation. The model is tested by reproducing the track and intensity of Cyclone Sidr of 2007. We also examine the projected future climate from the South Asia Regional Climate Model to understand how tropical cyclones may change under global warming and assess how this may impact the BGM Delta over the 21st century.

  11. Characterization of sampling cyclones

    E-print Network

    Moore, Murray Edward

    1986-01-01

    Presamplers, Ph. D, The- sis, Dept. oj Environmental Health, College of Medicine, Univ. of Cincinnati, (1976) 28 APPENDIX Table 1: Ratio of Dimensions to Cyclone Diameter Cyclone Cylinder Diameter, mm Height Inlet Exhaust Tube Gap Insertion 38. 10...: Nuclear Engineering CHARACTERIZATION OF SAMPLIVG CYCLONES A Thesis by MURRAY EDWARD MOORE Approved as to style and content by: Andrew R. Mc arland (Co-Chairman of Committee) Frederick R. Best (Co-Chairman of Committee) 7 4& pc~ Theodore A...

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

    PubMed

    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. PMID:22423166

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

    PubMed Central

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

    2012-01-01

    Abstract 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. PMID:22423166

  14. Cyclone Center Using Crowdsourcing to Determine Tropical Cyclone Intensity

    E-print Network

    Hennon, Christopher C.

    classification. Zooniverse, the delivery vehicle for the Citizen Science Alliance, developed the website. Changes in other observation technologies (e.g. microwave satellites) further complicate an agency's "best 1978-2009. Our analysts are "citizen scientist" volunteers from around the world. Most are not experts

  15. Catalyst attrition in cyclones

    Microsoft Academic Search

    J Reppenhagen; J Werther

    2000-01-01

    The mechanism of catalyst attrition in cyclones has been investigated both theoretically and experimentally for various types of catalysts. A model is suggested that considers cyclone attrition under steady-state conditions as a comminution process. It considers the efficiency of such a process by relating the surface energy created by comminution to the kinetic energy, which has been spent to create

  16. Tropical Storms, Worldwide

    NSDL National Science Digital Library

    The University of Hawaii's Mees Solar Observatory, stationed at Haleakala, Maui, provides a wealth of data and images in its Webpages. This page, Tropical Storms Worldwide, gives regional maps and written updates of hurricane, typhoon, and tropical cyclone activity around the globe. The page also features a strike probability calculator where users click on a list of geographic locations or enter map coordinates or a US zip code in order to view the probability of a tropical storm reaching that area. A storm data archive (1994-2000) and printer-friendly .pdf-formatted storm track maps are also available.

  17. Damping and pumping of a vortex Rossby wave in a monotonic cyclone: Critical layer stirring versus inertiabuoyancy wave emission

    E-print Network

    Schecter, David

    , in principle, con- tribute to the intensification of a swirling storm, such as an incipient tropical cyclone.2 monotonically with radius r. Early studies of 3D symmetrization4­10 assumed that the vortex motion

  18. A COMPARISON BETWEEN NEURAL NETWORKS AND MAXIMUM LIKELIHOOD REMOTELY SENSED DATA CLASSIFIERS TO DETECT TROPICAL RAIN LOGGED-OVER FOREST IN INDONESIA

    Microsoft Academic Search

    Anas Fauzi; Yousif Ali Hussin; Michael Weir

    Selective logging has been applied in the Indonesian tropical rain forest since the 1960. This has resulted thousands of hectare logged-over forest. In Labanan, Berau, East Kalimantan, selective logging will enter the second rotation in 2010. A comprehensive analysis on the logged over forest condition should be made before harvesting the logged over forest. One aspect that should be considered

  19. Tropical Cyclone ALMA, May 29, 2002

    NSDL National Science Digital Library

    Lori Perkins

    2002-05-31

    This is Hurricane Alma on May 29, 2002 as seen by TRMM and GOES. The animation zooms down to Hurricand Alma and then scans across the cloud tops to reveal the underlying rain structure. There are 3 isosurfaces defined (Yellow = 0.5 inches-hour, Green = 1.0 inches-hour, and Red = 2.0 nches-hour)

  20. Historical Global Tropical Cyclone Landfalls* JESSICA WEINKLE

    E-print Network

    Colorado at Boulder, University of

    created that might serve as a consistency check for such economic normalization studies. Using currently available historical TC best-track records, a global database focused on hurricane-force strength landfalls confidence to the fidelity of economic normalization analyses. 1. Introduction The active North Atlantic

  1. Les cyclones tropicaux et le changement climatique

    NASA Astrophysics Data System (ADS)

    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.

  2. Comparison of different tracking algorithms analysing subantarctic cyclones: A contribution to the IMILAST programme

    NASA Astrophysics Data System (ADS)

    Grieger, Jens; Leckebusch, Gregor C.; Raible, Christoph C.; Rudeva, Irina; Simmonds, Ian

    2015-04-01

    Cyclones are a dominant feature of the mid- and high-latitude atmospheric circulation, however their definition is not straightforward as their characteristics are complex. Thus, a number of studies present different objective cyclone detection and tracking algorithms focusing on different aspects of what is thought to be the main characteristic of a cyclone. For example, studies use either the rotational character of cyclones by using the vorticity as main field to identify cyclones or the mass character by using the pressure field. In this study, 14 different objective identification and tracking algorithms are compared by analyzing subantarctic cyclones. This region is of especial interest because it hosts the greatest frequencies of cyclogenesis and cyclone occurrence across the whole Southern Hemisphere. The character of cyclones there are strongly influenced by the intense baroclinicity and the presence of the Antarctic massif. The study is part of the Intercomparison of Mid Latitude STorm diagnostics (IMILAST) project. As a common basis ERA-Interim reanalysis data between 1979-2008 is used. This contribution investigates the output of the different tracking algorithms for the representation of extra-tropical cyclones around Antarctica, and all cyclone tracks south of 60° S are selected. We focus on three sectors around Antarctica, namely East Antarctica, Amundsen-Bellingshausen Seas, and Weddell Sea, for a differentiated comparison of the different tracking methodologies. A track-to-track analysis allows the evaluation of differences and similarities of the methodologies for the representation of subantarctic cyclones. As known from similar studies for the entire Southern Hemisphere, absolute numbers of identified cyclone tracks differ significantly. This is also the case for all sectors around Antarctica. Differences are even more pronounced in austral winter (JJA) due to the different treatment of cyclone intensities by the numerous tracking methods. However, the main features of the geographical distribution are well represented by the different algorithms, whereas major differences are found in the region of Ronne and Ross ice shelves. As would be expected, cyclone characteristics such as trajectories agree better when focusing on strong cyclones rather than analyzing all cyclones.

  3. Balanced thermal structure of an intensifying tropical By DAVID J. RAYMOND*, Physics Department and Geophysical Research Center, New Mexico Tech,

    E-print Network

    Raymond, David J.

    Balanced thermal structure of an intensifying tropical cyclone By DAVID J. RAYMOND*, Physics of a virtual potential temperature dipole in a developing tropical cyclone is a balanced response to the growth to the observed potential vorticity distribution is inverted subject to non-linear balance for two successive days

  4. The Morphology of Cyclonic Windstorms

    NASA Astrophysics Data System (ADS)

    Hewson, Tim

    2015-04-01

    The aim of this study is to help facilitate the correct interpretation and use of model analyses and predictions of windstorms in the extra-tropics, and to show that 'storm detection' does not just depend on the efficacy of the identification/tracking algorithm. Under the auspices of the IMILAST (Intercomparison of MId-LAtitude STorm diagnostics) project, 29 damaging European cyclonic windstorms have been studied in detail, using observational evidence as the main tool. Accordingly a conceptual model of windstorm evolution has been constructed. This usefully has its roots in the evolution one sees on standard synoptic charts, and highlights that three types of damage footprint can be associated. Building on previous work these are referred to as the warm jet, the sting jet and the cold jet footprints. The jet phenomena themselves each relate to the proximity of fronts on the synoptic charts, and accordingly occur in airmasses with different stability characteristics. These characteristics seem to play a large role in determining the magnitude of surface gusts, and how those gusts vary between coastal and inland sites. These aspects will be discussed with examples, showing that one cannot simply characterise or rank cyclones using wind strength on a lower tropospheric level such as 850hPa. A key finding that sets the sting jet apart, and that makes it a particularly dangerous phenomena, is that gust magnitude is relatively unaffected by passage inland, and this seems to relate to the atmosphere in its environment being destabilised from above. For sting jets wind strength may be greatest below 850hPa. Unfortunately neither current generation global re-analyses, nor global climate models seem to be able to simulate sting jets. This is for various reasons, though their low resolution is key. This limitation has been recognised previously, and the standard way to address this has been to use a re-calibration technique. The potential pitfalls of this approach will be highlighted using the aforementioned windstorm set to illustrate. Based again on case studies it will be shown that spatial resolution in a numerical model needs to be of order 10-20km to capture most major windstorms. However even then some of the smaller systems, which can be equally damaging, will be missed.

  5. Opposed-flow virtual cyclone for particle concentration

    DOEpatents

    Rader, Daniel J. (Lafayette, CA); Torczynski, John R. (Albuquerque, NM)

    2000-12-05

    An opposed-flow virtual cyclone for aerosol collation which can accurately collect, classify, and concentrate (enrich) particles in a specific size range. The opposed-flow virtual cyclone is a variation on the virtual cyclone and has its inherent advantages (no-impact particle separation in a simple geometry), while providing a more robust design for concentrating particles in a flow-through type system. The opposed-flow virtual cyclone consists of two geometrically similar virtual cyclones arranged such that their inlet jets are inwardly directed and symmetrically opposed relative to a plane of symmetry located between the two inlet slits. A top plate bounds both jets on the "top" side of the inlets, while the other or lower wall curves "down" and away from each inlet jet. Each inlet jet will follow the adjacent lower wall as it turns away, and that particles will be transferred away from the wall and towards the symmetry plane by centrifugal action. After turning, the two jets merge smoothly along the symmetry line and flow parallel to it through the throat. Particles are transferred from the main flows, across a dividing streamline, and into a central recirculating region, where particle concentrations become greatly increased relative to the main stream.

  6. A preliminary computer pattern analysis of satellite images of mature extratropical cyclones

    NASA Technical Reports Server (NTRS)

    Burfeind, Craig R.; Weinman, James A.; Barkstrom, Bruce R.

    1987-01-01

    This study has applied computerized pattern analysis techniques to the location and classification of features of several mature extratropical cyclones that were depicted in GOES satellite images. These features include the location of the center of the cyclone vortex core and the location of the associated occluded front. The cyclone type was classified in accord with the scheme of Troup and Streten. The present analysis was implemented on a personal computer; results were obtained within approximately one or two minutes without the intervention of an analyst.

  7. Cosmic Classifier

    NSDL National Science Digital Library

    This interactive, online activity allows students to examine the Hubble Deep Field image and simulate the process astronomers have gone through to classify the objects in it. Students classify select objects in the image based on observable properties such as color and shape. Students then compare their classifications to those made by astronomers. Upon completion of this activity, students will have classified objects in the Hubble Deep Field, described their characteristics, and used a table to display their data. Students can work through the activity independently or in groups. Teachers also may choose to have students prepare oral reports based on what they learned after performing the activity. Detailed teacher pages, identified as Teaching Tips on the title page of the activity, provide science background information, lesson plan ideas, related resources, and alignment with national education standards. This activity is part of the online exploration "The Hubble Deep Field Academy" that is available on the Amazing Space website.

  8. Cyclone Dera in the Mozambique Channel

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Sea-viewing Wide Field-of-view Sensor (SeaWiFS, flying aboard OrbView-2) saw Tropical Cyclone Dera shortly after it formed today (March 9, 2001) over the Mozambique Channel. Mozambique is visible to the left of the storm, and the island of Madagascar is partially visible on the right side of the storm. In the high-resolution image you can see the Zambeze River in Mozambique, which has been flooded in recent weeks. The signature brownish plumes of sediment discharge from the Zambeze into the channel are visible at several places along Mozambique's coastline. According to the U.S. Joint Typhoon Warning Center, Cyclone Dera now has sustained winds of 55 knots (about 63 mph or 102 km per hour), with gusts of up to 70 knots (81 mph or 130 km per hour). The storm is moving in a south-southeasterly direction at about 14 knots (16 mph or 26 km per hour). The storm is predicted to continue intensifying over the next 24 hours and should continue heading in a southerly direction. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  9. Evolution of Cyclone Characteristics The composite evolution of west and east Atlantic cyclone is likely to

    E-print Network

    Dacre, Helen

    Evolution of Cyclone Characteristics The composite evolution of west and east Atlantic cyclone. The spatial distribution and evolution characteristics of North Atlantic cyclones. Mon. Wea. Rev. 137, 99 characteristics and the evolution of these characteristics are calculated in composite cyclones. Method · Cyclones

  10. An integrated stormwater management approach for small islands in tropical climates

    Microsoft Academic Search

    Z. Vojinovic; J. Van Teeffelen

    2007-01-01

    In many tropical island settings in the world and as a result of human activities and tropical weather conditions, urban areas have been vulnerable to special kinds of hazards. The most common and the most widely experienced hazard events for these localities are tropical cyclones and accompanying storm surges, flash floods and landslides. Such events can cause serious damages to

  11. A climatological study: wet season cyclone tracks in the East Mediterranean region

    NASA Astrophysics Data System (ADS)

    Almazroui, Mansour; Awad, Adel M.; Islam, M. Nazrul; Al-Khalaf, A. K.

    2015-04-01

    This work identifies a total of 1,992 cyclone tracks over the East Mediterranean region using six hourly sea level pressure fields taken from National Center for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalysis for the period 1958-2010. A classification method is developed to classify the long-track cyclones into four key routes. Besides these, two other routes are considered, which are classified as either stationary or having a short track length. This study reveals that the East Mediterranean region has three main cyclogenesis areas and four main cyclolysis areas. Analysis of the relationships between the main cyclogenesis and cyclolysis areas indicates that the Anatolian Mountain region generates the largest number of cyclones and that they terminate in four cyclolysis areas. It is also found that 19.0, 29.4, and 51.6 % of the cyclones are stationary, short, and long tracks, respectively, while only 1.6 % of the cyclones are explosive. The average lifetime of the tracks is between 2 and 3 days, although a few live up to 5 or 6 days. The study of the synoptic composition of the routes indicates that the East Mediterranean cyclones are controlled by two key processes: (i) the possibility of merging tracks with low pressure systems over the Arabian Peninsula and (ii) the extensions of both the Azores and the Siberian highs into the East Mediterranean, as well as by the wind speeds in the upper atmosphere.

  12. P1.4 TOWARD A GLOBAL CLIMATOLOGY OF TROPICAL CLOUD CLUSTERS Christopher C. Hennon *

    E-print Network

    Hennon, Christopher C.

    remapping resolution and calibration normalization. We use the global #12;best track dataset (IBTrACS, Knapp the cloud cluster database. IBTrACS contains tropical cyclone tracks from every forecast and analysis center

  13. Combining Classifiers Sargur Srihari

    E-print Network

    Combining Classifiers Sargur Srihari srihari@cedar.buffalo.edu #12;Synononyms for the Topic · "Mixture of Experts" · "Ensemble Classifiers" · "Modular Classifiers" · "Pooled Classifiers" · "Combining. Component Classifiers with Discriminant Functions Use a principled statistical approach 2. Component

  14. Occurrence and characteristics of mesoscale eddies in the tropical northeast Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Schütte, Florian; Brandt, Peter; Karstensen, Johannes

    2015-04-01

    Coherent mesoscale features (referred to here as eddies) in the tropical northeast Atlantic (between 12°N - 22°N and 15°W - 26°W) are examined and characterised. Surface signatures of eddies were analysed using an eddy detection method based on 18 years of satellite altimetry data. Mean spatial eddy surface pattern of satellite derived anomalies of sea level (SLA), sea surface temperature (SST), salinity (SSS) and chlorophyll concentration (Chl) were obtained from composites of all snapshots around identified eddy cores. Three types of eddies could be identified: anticyclones, cyclones and anticyclonic-mode-water eddies. Anticyclones and cyclones can be distinguished due to their elevation/depression of SLA. In general, they are associated with warm/cold SST, reduced/enhanced Chl and enhanced/reduced SSS, respectively. However, 18% of all detected anticyclones show instead cold SST, enhanced Chl and reduced SSS. This kind of eddies are classified as anticyclonic-mode-water eddies. For all types of eddies three main eddy generation regions in the coastal upwelling region associated with headlands are identifiable. From these three generation regions, almost all eddies propagate westward along corridors with distinct meridional deflection (anticyclones - equatorward, cyclones - poleward, anticyclonic-mode-water eddies - no deflection). The generation of eddies follows distinct seasonal cycles with anticyclones predominantly generated during late boreal summer, cyclones during boreal winter and anticyclonic-mode-water eddies during early boreal summer. The mean vertical structure of the three eddy types was determined combining SLA eddy detection with all available in-situ temperature, salinity and oxygen profile data (Argo, ship, mooring data). Core depths of anticyclones/cyclones are at ~50m/~40m, respectively. The core depth of anticyclonic-mode-water eddies is at ~70m depth with positive/negative density anomaly above/below its core depth. The mean oxygen profile for the different eddy types suggests that anticyclones (cyclones) transport waters with high (low) oxygen concentration. In anticyclonic-mode-water eddies extremely low oxygen levels reaching suboxic or close to anoxic conditions have been observed. These open-ocean low-oxygen zones can develop due to a combination of eddy dynamics and biogeochemical cycling. The available oxygen datasets indicate