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1

Assessing Tropical Cyclone Damage  

NASA Astrophysics Data System (ADS)

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

Done, J.; Czajkowski, J.

2012-12-01

2

Tropical Cyclone Gonu  

NASA Technical Reports Server (NTRS)

You might expect to see a storm with near-perfect symmetry and a well-defined eye hovering over the warm waters of the Caribbean or in the South Pacific, but Tropical Cyclone Gonu showed up in an unusual place. On June 4, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this image, Tropical Cyclone Gonu was approaching the northeastern shore of Oman, a region better known for hot desert conditions. Though rare, cyclones like Gonu are not unheard of in the northern Indian Ocean basin. Most cyclones that form in the region form over the Bay of Bengal, east of India. Those that take shape over the Arabian Sea, west of the Indian peninsula, tend to be small and fizzle out before coming ashore. Cyclone Gonu is a rare exception. As of June 4, 2007, the powerful storm had reached a dangerous Category Four status, and it was forecast to graze Oman's northeastern shore, following the Gulf of Oman. According to storm statistics maintained on Unisys Weather, the last storm of this size to form over the Arabian Sea was Cyclone 01A, which tracked northwest along the coast of India between May 21 and May 28, 2001. Unlike Gonu's forecasted track, Cyclone 01A never came ashore. MODIS acquired this photo-like image at 12:00 p.m. local time (9:00 UTC), a few hours after the Joint Typhoon Warning Center estimated Gonu's sustained winds to be over 240 kilometers per hour (145 miles per hour). The satellite image confirms that Gonu was a super-powerful cyclone. The storm has the hallmark tightly wound arms that spiral around a well-defined, circular eye. The eye is surrounded by a clear wall of towering clouds that cast shadows on the surrounding clouds. Called hot towers, these clouds are a sign of the powerful uplift that feeds the storm. The symmetrical spirals, clear eye, and towering clouds are all features regularly seen in satellite images of other particularly powerful cyclones, which are also known as typhoons or hurricanes when they form in other parts of the world. The high-resolution image provided above is at MODIS' full spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response System provides this image at additional resolutions.

2007-01-01

3

Tropical Cyclone Eye Thermodynamics  

Microsoft Academic Search

In intense tropical cyclones, sea level pressures at the center are 50-100 hPa lower than outside the vortex, but only 10-30 hPa of the total pressure fall occurs inside the eye between the eyewall and the center. Warming by dry subsidence accounts for this fraction of the total hydrostatic pressure fall. Convection in the eyewall causes the warming by doing

H. E. Willoughby

1998-01-01

4

ENSO and Tropical Cyclone Activity  

Microsoft Academic Search

The present state of knowledge regarding tropical cyclone activity in various ocean basins and the El Niño-Southern Oscillation phenomenon is reviewed in this chapter. The ocean basins include the western North Pacific, the eastern and central North Pacific, the southwestern Pacific, the southeastern Pacific, and the North Atlantic. Following a description of the ENSO phenomenon, tropical cyclone activity in each

Pao-Shin Chu

5

Tropical Cyclone Intensity Analysis  

NSDL National Science Digital Library

This lesson provides guidance for operational forecasters needing to combine different intensity methods to determine the intensity of a tropical cyclone. Each of the intensity methods is summarized, focusing on both strengths and weaknesses. These methods include the Dvorak technique, surface observations, scatterometry, the Advanced Dvorak Technique (ADT), microwave sounders (AMSU), SATCON, and subjective interpretation of passive microwave patterns. Consideration of the previous intensity estimate and forecast is also examined. Three case studies task the learner with combining the various methods to derive appropriate intensity estimates and a final quiz tests learner knowledge to demonstrate successful completion of the lesson.

Comet

2014-05-15

6

Tropical Cyclones and Climate Change  

E-print Network

Whether the characteristics of tropical cyclones have changed or will change in a warming climate — and if so, how — has been the subject of considerable investigation, often with conflicting results. Large amplitude ...

Knutson, Thomas R.

7

Black Swan Tropical Cyclones  

NASA Astrophysics Data System (ADS)

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.

Emanuel, K.; Lin, N.

2012-12-01

8

Polytropic process and tropical Cyclones  

E-print Network

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

Romanelli, Alejandro; Rodríguez, Juan

2013-01-01

9

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

10

Tropical Cyclone Report Hurricane Katrina  

E-print Network

1 Tropical Cyclone Report Hurricane Katrina 23-30 August 2005 Richard D. Knabb, Jamie R. Rhome, and damage cost estimates Katrina was an extraordinarily powerful and deadly hurricane that carved a wide deadliest hurricanes to ever strike the United States. Katrina first caused fatalities and damage

11

Fluid Mechanics of Tropical Cyclones  

NASA Astrophysics Data System (ADS)

Typhoons in the northwest Pacific and hurricanes in the northeast Atlantic are particular instances of a global phenomenon with frequently disastrous consequences known as the Tropical Cyclone (TC). This is an intense cyclone, generated over a tropical ocean with kinetic energy 1018 J or more, which extends over several hundred kilometres and yet is above all characterized by its calm central region: ``the eye of the storm''. In a TC (not, of course, to be confused with such completely different phenomena as tornadoes) both the energy input and its dissipation mainly occur within that boundary layer between air and ocean which, at high TC wind speeds of 50-60 m/s, comprises essentially ``a third fluid'': ocean spray. Afterwards, as a TC reaches land, disastrous effects of several different kinds may occur, and this paper outlines how fluid mechanics contributes towards worldwide struggles to reduce the human impact of TC disasters.

Lighthill, James, Sir

12

Global trends in tropical cyclone risk  

NASA Astrophysics Data System (ADS)

The impact of tropical cyclones on humans depends on the number of people exposed and their vulnerability, as well as the frequency and intensity of storms. How will the cumulative effects of climate change, demography and vulnerability affect risk? Conventionally, reports assessing tropical cyclone risk trends are based on reported losses, but these figures are biased by improvements to information access. Here we present a new methodology based on thousands of physically observed events and related contextual parameters. We show that mortality risk depends on tropical cyclone intensity, exposure, levels of poverty and governance. Despite the projected reduction in the frequency of tropical cyclones, projected increases in both demographic pressure and tropical cyclone intensity over the next 20 years can be expected to greatly increase the number of people exposed per year and exacerbate disaster risk, despite potential progression in development and governance.

Peduzzi, P.; Chatenoux, B.; Dao, H.; de Bono, A.; Herold, C.; Kossin, J.; Mouton, F.; Nordbeck, O.

2012-04-01

13

Tropical Cyclones as a Critical Phenomenon  

E-print Network

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

Corral, A

2011-01-01

14

Climatology of landfalling tropical cyclones in Bangladesh 1877–2003  

Microsoft Academic Search

Bangladesh is highly susceptible to tropical cyclones. Unfortunately, there is a dearth of climatological studies on the tropical\\u000a cyclones of Bangladesh. The Global Tropical Cyclone Climatic Atlas (GTCCA) lists historical storm track information for all\\u000a the seven tropical cyclone ocean basins including the North Indian Ocean. Using GIS, tropical cyclones that made landfall\\u000a in Bangladesh during 1877–2003 are identified and

Tanveerul Islam; Richard E. Peterson

2009-01-01

15

How can tropical cyclones survive?  

NASA Astrophysics Data System (ADS)

How can tropical cyclones survive? It is important for understanding the development of tropical cyclones to be able to quantify the exchange of enthalpy and momentum between air and water. Air-sea fluxes are often formulated as drag CD and enthalpy CK exchange coefficients. Emanuel, 1986, derived an expression for potential intensity that depends on local environment parameters and is proportional to the ratio of enthalpy and drag coefficients. This ratio should be larger than 0.75 for a cyclone to develop. There are no direct surface measurements of CK/ CD under hurricane conditions and extrapolation from most open-ocean measurements at 25 m/s gives values of CK/ CD< 0.75 and in that case no cyclone could survive and Emanuel's theory must be wrong. However there are measurements of CK taken over the Baltic Sea and Lake Ontario showing increasing values of CK up to 2.5 for wind speeds around 12 m/s. If this can be implemented for hurricane conditions the ratio CK/ CD>0.75 is in accordance with Emanuel's prediction. The high CK values are observed during situations when there is a regime shift of the structure of turbulence in the boundary layer. From spectral analysis it was found that as the boundary layer approaches neutral stratification, smaller-scale eddies become increasingly important in the turbulent transport of humidity and sensible heat and thus enhance the exchange coefficient CK. This turbulence regime is called the UVCN regime and require high wind speed, small temperature difference between air and water, sufficiently strong wind gradients and growing sea condition ( Smedman et al., 2007, Sahlee et al., 2008). What is the difference between world oceans and enclosed seas? The answer is the waves. The wave field over the open oceans is swell dominated but in enclosed seas and coastal areas swell is restricted mainly to low wind speed conditions, and swell is short lived because of short distances to the shores. When swell is present the MABL will be dominated by large eddies of zi size creating weak gradients of wind, temperature and humidity and thus small scale eddies cannot be formed leading to reduced CK-values. However, during hurricane condition the waves are expected to be young, stratification is close to neutral and gradients are sufficiently large to generate UVCN condition and thus increased CK values. References: K. A. Emanuel, 1986: An air-sea interaction theory for tropical cyclones, part I: Steady-state maintenance, J. Atmos. Sci., 43,585-604 E. Sahlee et al., 2008: Reevaluation of bulk exchange coefficient for humiditu at sea during unstable and neutral conditions, DOI:10.1175/2007JPO3754.1 A. Smedman, 2007: Heat/mass transfer in the slightly unstable atmospheric surface layer,Quart. J. Meteorol. Soc., 133, 37-51

Smedman, Ann-Sofi

2013-04-01

16

Midlevel ventilation's constraint on tropical cyclone intensity  

E-print Network

Midlevel ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hypothesized mechanism by which environmental vertical wind shear can constrain a TC's intensity. An idealized ...

Tang, Brian Hong-An

2010-01-01

17

Tropical Cyclone Jack in Satellite 3-D  

NASA Video Gallery

This 3-D flyby from NASA's TRMM satellite of Tropical Cyclone Jack on April 21 shows that some of the thunderstorms were shown by TRMM PR were still reaching height of at least 17 km (10.5 miles). ...

18

Nuclear power plant risk from tropical cyclones  

Microsoft Academic Search

Tropical cyclones are considered to have a potential for contributing to the overall core-melt frequency at Turkey Point. A tropical cyclone is known to have the four main hazards associated with it: wind, tidal surge, wind-generated missiles, and precipitation. To understand the contribution to overall core-melt risk at Turkey Point, it is essential to understand the mechanisms of these hazards

1991-01-01

19

The Caribbean Sea and Tropical Cyclones  

NASA Astrophysics Data System (ADS)

Observations have shown a significant interannual and multi-decadal variability in track and intensity of tropical cyclones in the Caribbean Sea. The environmental conditions seem to favour tropical cyclone activity in the western part of the basin while the atmospheric deep convection are generally suppressed over the eastern Caribbean Sea. Over the last a few decades tropical cyclone track forecasts have improved significantly, whereas very little progress made in tropical cyclone intensity forecasts. The lack of the skill in the intensity forecasts may be attributed to deficiencies in the current prediction models: insufficient horizontal resolution, inadequate surface and boundary layer formulations, and no full coupling to the ocean. The extreme high winds, intense rainfall, large ocean waves, and copious sea spray push the surface-exchange parameters for temperature, water vapor, and momentum into untested new regimes. To resolve the hurricane eyewall structure, crucial in intensity forecasting, the horizontal resolution need to be at ~1-2 km. The air-sea interaction in the Caribbean Sea region is largely unknown with very little observations. While tropical cyclones draw energy from the ocean surface, they cool the ocean by wind-induced surface fluxes and vertical mixing. The effects of the warm SST and deep upper-ocean mixed layer in the Caribbean Sea on tropical cyclone formation and evolution are investigated using the high-resolution atmospheric model and ocean mixed layer model.

Chen, S. S.

2001-12-01

20

Projected increase in tropical cyclones near Hawaii  

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

21

Tropical cyclone boundary layer shocks  

E-print Network

This paper presents numerical solutions and idealized analytical solutions of axisymmetric, $f$-plane models of the tropical cyclone boundary layer. In the numerical model, the boundary layer radial and tangential flow is forced by a specified pressure field, which can also be interpreted as a specified gradient balanced tangential wind field $v_{\\rm gr}(r)$ or vorticity field $\\zeta_{\\rm gr}(r)$. When the specified $\\zeta_{\\rm gr}(r)$ field is changed from one that is radially concentrated in the inner core to one that is radially spread, the quasi-steady-state boundary layer flow transitions from a single eyewall shock-like structure to a double eyewall shock-like structure. To better understand these structures, analytical solutions are presented for two simplified versions of the model. In the simplified analytical models, which do not include horizontal diffusion, the $u(\\partial u/\\partial r)$ term in the radial equation of motion and the $u[f+(\\partial v/\\partial r)+(v/r)]$ term in the tangential equat...

Slocum, Christopher J; Taft, Richard K; Schubert, Wayne H

2014-01-01

22

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

NASA Technical Reports Server (NTRS)

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.

Chen, L.; Gray, W. M.

1985-01-01

23

The Tropical East Pacific as a Laboratory for Tropical Cyclones  

NASA Astrophysics Data System (ADS)

The summertime tropical cyclogenesis rate per unit area in the eastern Pacific ocean is arguably higher than in any other location in the world. Many if not most of these cyclones form from African easterly waves which cross Central America into the Pacific. Of order 25% of these waves intensify into cyclones. A significant fraction of east Pacific tropical cyclones undergoes landfall on the Mexican coast. Those which do not, generally dissipate over cold ocean waters north of the east Pacific intertropical convergence zone, often not far from land. The layer of warm ocean water which supports the development of east Pacific cyclones is unusually shallow and is structured by anticyclonic vortices which form by various processes and propagate slowly to the west. These vortices locally deepen the oceanic mixed layer and support stronger convection than their surroundings, possibly promoting cyclogenesis and cyclone intensification. Cyclones in turn have an unusually large effect on the ocean mixed layer due to its shallowness. The east Pacific is thus a region of strong coupling between the atmosphere and the ocean, mediated in large part by the action of tropical cyclones. In most cases cyclogenesis, intensification, landfall, and decay over cold water occur within easy range of research aircraft launched from a number of Central American and Mexican bases such as San Jose, Huatulco, Acapulco, Puerto Vallarta, and Cabo San Lucas. The U. S. National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration have all successfully operated aircraft-based research projects from one or more of these locations. The frequency with which cyclones form, develop, and decay in the east Pacific and their proximity to land bases with excellent facilities make the tropical east Pacific an ideal international laboratory for the study of tropical cyclones. Given the importance of these cyclones to global weather and climate, every effort should be made to take advantage of this natural laboratory to enhance our knowledge of this phenomenon.

Raymond, D. J.

2007-05-01

24

Modelling Atlantic Basin Tropical Cyclone Storm Tracks  

NASA Astrophysics Data System (ADS)

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.

Hardisty, F.; Carroll, D.

2011-12-01

25

Reanalyzing Tropical Cyclone Intensities with Citizen Scientists  

NASA Astrophysics Data System (ADS)

Tropical cyclones are among the most destructive weather phenomena. Whenever possible, the intensities of these storms have been determined from in situ data or aircraft reconnaissance. More often, however, they are estimated subjectively from satellite data using the Dvorak technique. Heterogeneities are introduced into the historical record with the evolution of operational procedures, personnel, and observing platforms. In some cases, multiple agencies even arrive at different estimates for the same storm. These uncertainties impede our ability to identify the relationship between tropical cyclone intensities and climate change. NOAA's NCDC has produced a 30-year (1979-2008) homogeneous dataset (HURSAT) of tropical cyclone imagery from geostationary satellites. This dataset has the potential to address some of the uncertainties in the recent tropical cyclone record. However, it would take nearly 40 years for a trained expert, working nonstop, to apply the Dvorak technique to all 200,000 images. Harnessing the power of thousands of Citizen Scientists, the same task can be completed in a matter of months. This presentation will explain how the Dvorak technique was adapted for Citizen Scientists, and how their skill will be evaluated relative to the operational analyses by trained experts.

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

2012-12-01

26

Tropical cyclone trends in the Australian region  

Microsoft Academic Search

Tropical cyclone trends in the Australian region are examined using the Bureau of Meteorology best track data. Here the focus is on analyzing differences in trends between the eastern and western subregions of the Australian formation region, under the assumption that any spurious trends in the best track data due to changes in observational practices would be less noticeable in

Muhammad E. E. Hassim; Kevin J. E. Walsh

2008-01-01

27

Nuclear power plant risk from tropical cyclones  

SciTech Connect

Tropical cyclones are considered to have a potential for contributing to the overall core-melt frequency at Turkey Point. A tropical cyclone is known to have the four main hazards associated with it: wind, tidal surge, wind-generated missiles, and precipitation. To understand the contribution to overall core-melt risk at Turkey Point, it is essential to understand the mechanisms of these hazards and their relative importance. The results are bounded by the hurricane surge scenario, where the frequency of core melt is equal to the frequency of the surge reaching 19 ft NGVD (National Geographic Vertical Datum). This could be mitigated by potential recovery actions for the tropical cyclone scenario. The probability of the storm surge reaching 19 ft NVGD is estimated to be 1 x 10{sup {minus}4}. The data associated with the tropical cyclones as discussed in detail in the body of this paper are lacking in quantity and quality. By taking the conservative approach in creating the wind/frequency, wind/surge, and surge/frequency relationships, the conclusion that the results are worst case is reasonable. With this in mind, it is logical to conclude that the value of further hazard analysis to narrow down the built-in conservative margin using the existing data and technology is doubtful. Thus, a recovery approach to driving the risk level down is the most pragmatic step to be taken.

Gilmore, T.F. (Florida Power and Light Co., Juno Beach (United States))

1991-01-01

28

Atlantic Tropical Cyclones in the 20th Natural Variability and Secular Change in Cyclone Count  

E-print Network

Atlantic Tropical Cyclones in the 20th Century: Natural Variability and Secular Change in Cyclone@atmos.umd.edu Keywords: Tropical cyclone counts; sea surface temperature; natural variability; secular change. #12 to develop consistent estimates of its natural variability and secular change components. The analysis scheme

Nigam, Sumant

29

Model finds bigger, stronger tropical cyclones with warming seas  

NASA Astrophysics Data System (ADS)

In the wake of powerful tropical cyclones such as Hurricanes Sandy and Katrina and Typhoon Haiyan, questions about the likely effect of climate change on tropical cyclone activity are on the public's mind. The interactions between global warming and cyclone activity, however, are complex, with rising sea surface temperatures, changing energy distributions, and altered atmospheric dynamics all having some effect.

Schultz, Colin

2014-03-01

30

Tropical Cyclone Occurrences in the Vicinity of Hawaii: Are the Differences between El Niño and Non-El Niño Years Significant?  

Microsoft Academic Search

Tropical cyclones in the vicinity of Hawaii are rare. However, when they occurred, they caused enormous property damage. The authors have examined historical records (1949-95) of cyclones and classified them into El Niño and non-El Niño batches. A bootstrap resampling method is used to simulate sampling distributions of the annual mean number of tropical cyclones for the above two batches

Pao-Shin Chu; Jianxin Wang

1997-01-01

31

FAQ: Hurricanes, Typhoons, and Tropical Cyclones  

NSDL National Science Digital Library

This website contains the answers to over 50 questions relating the characteristics of typhoons, tropical cyclones, and hurricanes. It covers a wide variety of topics, from basic definitions to myths, names, winds, forecasting, and historical information. The answers to the questions contain charts, graphs, text, and illustrations for a thorough explanation. When appropriate, links are given for more details. This site is also available in Spanish and French.

Landsea, Christopher

32

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

E-print Network

. 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...

Hales, Billy

2012-07-16

33

Remote forcing of water levels by tropical cyclones in southwest Australia  

NASA Astrophysics Data System (ADS)

Tropical cyclones (termed hurricanes and typhoons in other regions), are extreme events associated with strong winds, torrential rain and storm surges (in coastal areas) and cause extensive damage as a result of strong winds and flooding (caused by either heavy rainfall or ocean storm surges) in the immediate area of impact. The eastern Indian Ocean, particularly in the northwest region of Australia, is impacted by up to 10 tropical cyclones during the cyclone season, although direct impact of cyclones along the west and southwest coastlines is rare. However, the sub-tidal frequency component of sea level records along the west and south coasts of Western Australia indicates lagged correspondence with the occurrence of tropical cyclones. It is demonstrated that the tropical cyclones generate a continental shelf wave which travels along the west and south coasts of Australia up to 3500 km with speeds of 450-500 km day -1 (5.2-5.8 ms -1) with maximum trough to crest wave height of 0.63 m, comparable with the mean daily tidal range in the region. The shelf wave is identified in the coastal sea level records, initially as a decrease in water level, 1-2 days after the passage of the cyclone and has a period of influence up to 10 days. Amplitude of the shelf wave was strongly affected by the path of the tropical cyclone, with cyclones travelling parallel to the west coast typically producing the most significant signal due to resonance and superposition with local forcing. Analysis of water levels from Port Hedland, Geraldton, Fremantle and Albany together with cyclone paths over a ten year period (1988-1998) indicated that the tropical cyclones paths may be classified into 6 different types based on the amplitude of the wave.

Eliot, Matthew; Pattiaratchi, Charitha

2010-08-01

34

Tropical Cyclones and the Carbon Cycle  

NASA Astrophysics Data System (ADS)

The relationship between tropical cyclones and the carbon cycle poses an interesting question: tropical surface waters are generally quite warm and poor in nutrients, but the mixing in tropical cyclones entrains potentially large amounts of cold, nutrient-rich water. As the cold anomaly warms, there is a tendency toward over-saturation of carbon dioxide, and thus a net outgassing from the ocean to the atmosphere, but because nutrients are mixed into the photic zone, there is a simultaneous phytoplankton bloom which removes carbon from the mixed layer. The amount of carbon taken up into biota by the induced biological activity can in some cases create a net undersaturation of carbon dioxide in spite of the warming of entrained cold water, and therefore cause a net ingassing of carbon in the wake of a tropical cyclone. This is, however, only a short-term effect. Phytoplankton have a short life cycle, and the detritus they leave behind sinks and remineralizes; that which remineralizes below the climatological mixed layer represents a long-term sink of carbon from the atmosphere to the mixed layer, but the remainder will quickly return to the atmosphere. Both the warming of the mixed layer and the induced phytoplankton bloom are easily observable, but neither the sign nor the magnitude of the net effect is intuitive. To illuminate the question, a simple one-dimensional model is formulated which simulates the behavior of the upper few hundred meters of the ocean in response to tropical cyclone-induced mixing. Phytoplankton (and its remains), Nitrate, and Dissolved Inorganic Carbon are tracked, and the model is both initialized and forced with the best possible approximation to real chemical concentrations, winds, and heat fluxes, and the effect of the storm is estimated by comparing model behavior with the storm included and with the storm removed from observations. It is shown that the model performs acceptably well compared to such observations as exist. The model is then used to estimate the net flux of carbon between the deep ocean and the atmosphere for a large number of tropical cyclones around the world over the period 1999-2007. It is found that while in a few cases there is a large flux of carbon from the atmosphere to the deep ocean due biological sinking, for a large majority of storms the effect is quite small. For storms to cause a large carbon sink, they must be rather strong, and they must pass over a region of ocean with a both shallow nutricline and a relatively low stratification. While Typhoon Chanchu, which passed through the South China Sea in 2006, caused a large and well-studied sink of carbon that gave some initial cause for optimism that tropical cyclones might in general cause a similar effect, it now appears that such events are both too infrequent and cover too small an area to be a critical part of the carbon cycle in the current climate. It is reasoned that this may not necessarily be the case for previous climates with many more and stronger tropical cyclones, e.g. the early Pliocene.

Zimmerman, N. L.; Emanuel, K.

2010-12-01

35

Data Analysis of Tropical Cyclone Size  

NASA Astrophysics Data System (ADS)

The geometric size of a tropical cyclone (TC) is directly related to its destructive potential. However, widely used measures for TC activity and destructive potential, such as the accumulated cyclone energy (ACE) and power dissipation index (PDI), are based on maximum wind speed, without considering storm size. Our analysis of the Automated Tropical Cyclone Forecast (ATCF), Joint Typhoon Warning Center (JWTC), and National Hurricane Center (NHC) best track data shows that storm size is positively correlated with TC intensity and translation speed globally. The revised ACE and PDI (RACE and RPDI) take into account storm size but do not have a significant effect on annual trends for TC activity and destructive potential. In the Atlantic basin (AL), TC activity and destructiveness measures bear positive correlations with HadISST September sea surface temperature in both short and long term analysis. In the Western Pacific basin (WP), the annual trends of RACE and RPDI exhibit much stronger correlations with local August SST than ACE and PDI. Both results imply a potentially strong linkage between global warming and hurricane destructiveness.

Tang, N. W.; Su, H.

2012-12-01

36

Tropical cyclone intensities from satellite microwave data  

NASA Technical Reports Server (NTRS)

Radial profiles of mean 1000 mb to 250 mb temperature from the Nimbus 6 scanning microwave spectrometer (SCAMS) were constructed around eight intensifying tropical storms in the western Pacific. Seven storms showed distinct inward temperature gradients required for intensification; the eighth displayed no inward gradient and was decaying 24 hours later. The possibility that satellite data might be used to forecast tropical cyclone turning motion was investigated using estimates obtained from Nimbus 6 SCAMS data tapes of the mean 1000 mb to 250 mb temperature field around eleven tropical storms in 1975. Analysis of these data show that for turning storms, in all but one case, the turn was signaled 24 hours in advance by a significant temperature gradient perpendicular to the storm's path, at a distance of 9 deg to 13 deg in front of the storm. A thresholding technique was applied to the North Central U.S. during the summer to estimate precipitation frequency. except

Vonderhaar, T. H.; Kidder, S. Q.

1980-01-01

37

Ocean Barrier Layers’ Effect on Tropical Cyclone Intensification  

SciTech Connect

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.

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

2012-09-04

38

Ocean barrier layers' effect on tropical cyclone intensification.  

PubMed

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. PMID:22891298

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

2012-09-01

39

Tropical cyclone preparedness and response : opportunities for operations research  

E-print Network

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 ...

Murphy, Maurice D

2008-01-01

40

Diurnal analysis of intensity trends in Atlantic tropical cyclones  

E-print Network

I postulate that a diurnal cycle may exist in observational variables related to tropical cyclone (TC) intensity. Prior studies document a significant diurnal signal in moist convection across tropical regions. Since ...

Kowch, Roman S

2013-01-01

41

Detailed structure within a tropical cyclone ``eye''  

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

42

Atlantic tropical cyclones in the twentieth century: natural variability and secular change in cyclone count  

E-print Network

% of the decadal count variance as opposed to *30% for MDR SST. Atlantic Multidecadal Oscillation (AMO) dominatesAtlantic tropical cyclones in the twentieth century: natural variability and secular change of Atlantic tropical cyclones (TCs) is analyzed to develop consistent estimates of its natural variability

Nigam, Sumant

43

Modeling of tropical cyclone winds and waves for emergency management  

Microsoft Academic Search

This paper compares three commonly used parametric models of tropical cyclone winds and evaluates their application in the wave model WAM. The parametric models provide surface wind fields based on best tracks of tropical cyclones and WAM simulates wave growth based on the wind energy input. The model package is applied to hindcast the wind and wave conditions of Hurricane

Amal C. Phadke; Christopher D. Martino; Kwok Fai Cheung; Samuel H. Houston

2003-01-01

44

Improvements in Real-Time Tropical Cyclone Products  

E-print Network

DeMaria ­ Improvements in the Statistical Hurricane Intensity Prediction Scheme (SHIPS) for the 2007 Hurricane Season · John Knaff ­ The RAMMB Experimental Tropical Cyclone Web Page · Andrea Schumacher ­ Extension of the NESDIS operational tropical cyclone formation probability product to the Central

Kuligowski, Bob

45

Tropical Cyclone Boura on November 17, 2002  

NSDL National Science Digital Library

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.

Perkins, Lori; Halverson, Jeff

2002-11-21

46

Sea turtle species vary in their susceptibility to tropical cyclones.  

PubMed

Severe climatic events affect all species, but there is little quantitative knowledge of how sympatric species react to such situations. We compared the reproductive seasonality of sea turtles that nest sympatrically with their vulnerability to tropical cyclones (in this study, "tropical cyclone" refers to tropical storms and hurricanes), which are increasing in severity due to changes in global climate. Storm surges significantly decreased reproductive output by lowering the number of nests that hatched and the number of hatchlings that emerged from nests, but the severity of this effect varied by species. Leatherback turtles (Dermochelys coriacea) began nesting earliest and most offspring hatched before the tropical cyclone season arrived, resulting in little negative effect. Loggerhead turtles (Caretta caretta) nested intermediately, and only nests laid late in the season were inundated with seawater during storm surges. Green turtles (Chelonia mydas) nested last, and their entire nesting season occurred during the tropical cyclone season; this resulted in a majority (79%) of green turtle nests incubating in September, when tropical cyclones are most likely to occur. Since this timing overlaps considerably with the tropical cyclone season, the developing eggs and nests are extremely vulnerable to storm surges. Increases in the severity of tropical cyclones may cause green turtle nesting success to worsen in the future. However, published literature suggests that loggerhead turtles are nesting earlier in the season and shortening their nesting seasons in response to increasing sea surface temperatures caused by global climate change. This may cause loggerhead reproductive success to improve in the future because more nests will hatch before the onset of tropical cyclones. Our data clearly indicate that sympatric species using the same resources are affected differently by tropical cyclones due to slight variations in the seasonal timing of nesting, a key life history process. PMID:17479295

Pike, David A; Stiner, John C

2007-08-01

47

How ocean color can steer Pacific tropical cyclones  

NASA Astrophysics Data System (ADS)

Because ocean color alters the absorption of sunlight, it can produce changes in sea surface temperatures with further impacts on atmospheric circulation. These changes can project onto fields previously recognized to alter the distribution of tropical cyclones. If the North Pacific subtropical gyre contained no absorbing and scattering materials, the result would be to reduce subtropical cyclone activity in the subtropical Northwest Pacific by 2/3, while concentrating cyclone tracks along the equator. Predicting tropical cyclone activity using coupled models may thus require consideration of the details of how heat moves into the upper thermocline as well as biogeochemical cycling.

Gnanadesikan, Anand; Emanuel, Kerry; Vecchi, Gabriel A.; Anderson, Whit G.; Hallberg, Robert

2010-09-01

48

Coastal flooding by tropical cyclones and sea-level rise.  

PubMed

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

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

2013-12-01

49

Electromagnetohydrodynamic nature of tropical cyclones, hurricanes, and tornadoes  

NASA Astrophysics Data System (ADS)

The problem of genesis and intensification of tropical cyclones, hurricanes, and tornadoes is highly important in meteorology and to date has not been solved. At the same time, practically all researches made concerning these phenomena fail to take into account that the origin and intensification of tropical cyclones, hurricanes, and tornadoes take place under conditions of an abnormally strong electric field which together with electromagnetohydrodynamic interaction occupies a key position in the intensification process. The detailed description of the electromagnetohydrodynamic model explaining the processes of energy conversion in tropical cyclones, hurricanes, and tornadoes is presented.

Krasilnikov, Evgeny Y.

1997-06-01

50

Analysis of Tropical Cyclone Tracks in the North Indian Ocean  

NASA Astrophysics Data System (ADS)

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.

Patwardhan, A.; Paliwal, M.; Mohapatra, M.

2011-12-01

51

Asymmetric and axisymmetric dynamics of tropical cyclones  

NASA Astrophysics Data System (ADS)

We present the results of idealized numerical experiments to examine the difference between tropical cyclone evolution in three-dimensional (3-D) and axisymmetric (AX) model configurations. We focus on the prototype problem for intensification, which considers the evolution of an initially unsaturated AX vortex in gradient-wind balance on an f plane. Consistent with findings of previous work, the mature intensity in the 3-D model is reduced relative to that in the AX model. In contrast with previous interpretations invoking barotropic instability and related horizontal mixing processes as a mechanism detrimental to the spin-up process, the results indicate that 3-D eddy processes associated with vortical plume structures can assist the intensification process by contributing to a radial contraction of the maximum tangential velocity and to a vertical extension of tangential winds through the depth of the troposphere. These plumes contribute significantly also to the azimuthally averaged heating rate and the corresponding azimuthal-mean overturning circulation. The comparisons show that the resolved 3-D eddy momentum fluxes above the boundary layer exhibit counter-gradient characteristics during a key spin-up period, and more generally are not solely diffusive. The effects of these eddies are thus not properly represented by the subgrid-scale parameterizations in the AX configuration. The resolved eddy fluxes act to support the contraction and intensification of the maximum tangential winds. The comparisons indicate fundamental differences between convective organization in the 3-D and AX configurations for meteorologically relevant forecast timescales. While the radial and vertical gradients of the system-scale angular rotation provide a hostile environment for deep convection in the 3-D model, with a corresponding tendency to strain the convective elements in the tangential direction, deep convection in the AX model does not suffer this tendency. Also, since during the 3-D intensification process the convection has not yet organized into annular rings, the azimuthally averaged heating rate and radial gradient thereof is considerably less than that in the AX model. This lack of organization results broadly in a slower intensification rate in the 3-D model and leads ultimately to a weaker mature vortex after 12 days of model integration. While azimuthal mean heating rates in the 3-D model are weaker than those in the AX model, local heating rates in the 3-D model exceed those in the AX model and at times the vortex in the 3-D model intensifies more rapidly than AX. Analyses of the 3-D model output do not support a recent hypothesis concerning the key role of small-scale vertical mixing processes in the upper-tropospheric outflow in controlling the intensification process. In the 3-D model, surface drag plays a particularly important role in the intensification process for the prototype intensification problem on meteorologically relevant timescales by helping foster the organization of convection in azimuth. There is a radical difference in the behaviour of the 3-D and AX simulations when the surface drag is reduced or increased from realistic values. Borrowing from ideas developed in a recent paper, we give a partial explanation for this difference in behaviour. Our results provide new qualitative and quantitative insight into the differences between the asymmetric and symmetric dynamics of tropical cyclones and would appear to have important consequences for the formulation of a fluid dynamical theory of tropical cyclone intensification and mature intensity. In particular, the results point to some fundamental limitations of strict axisymmetric theory and modelling for representing the azimuthally averaged behaviour of tropical cyclones in three dimensions.

Persing, J.; Montgomery, M. T.; McWilliams, J. C.; Smith, R. K.

2013-12-01

52

Tropical Cyclone Crystal on December 25, 2002  

NSDL National Science Digital Library

Tropical Cyclone Crystal approaches the island of Mauritius in the Indian Ocean. The storm packed sustained winds of 80 miles per hour with gusts up to 96 miles per hour. Mauritius is situated east of Madagascar off of the Africas southeastern coast. This animation shows the storms rain structure 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.

Perkins, Lori; Halverson, Jeff

2002-12-30

53

Hurricane Earl, September 1, 2010/NOAA Tropical Cyclones  

E-print Network

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

Fang, Yuguang "Michael"

54

Tropical cyclone size in observations and in radiative-convective equilibrium  

E-print Network

Tropical cyclone size remains an unsolved problem in tropical meteorology, yet size plays a significant role in the damage caused by tropical cyclones due to wind, storm surge, and inland freshwater flooding. This work ...

Chavas, Daniel Robert

2013-01-01

55

Tropical Cyclone Mahasen Rain Moving Into Bay Of Bengal  

NASA Video Gallery

This animated TRMM Multisatellite Precipitation Analysis shows the rainfall that occurred with Tropical Cyclone Mahasen during the week of May 6 through 13, 2013 as it moved through the Bay of Beng...

56

TRMM Sees Rainfall Totals from Tropical Cyclone Guito  

NASA Video Gallery

This animation of rainfall gathered from February 11-19, 2014 by NASA's TRMM satellite revealed that Tropical Cyclone Guito produced as much as 16.9 inches/430 mm of rainfall in the center of the M...

57

Rainfall Totals from the Tropical Cyclones Passing Over Philippines  

NASA Video Gallery

Rainfall totals from the TRMM satellite of all tropical cyclones that passed through the Philippines from January through November 11, 2013. Red indicated areas where rainfall totals were greater t...

58

Tropical Cyclone Center Locations from Enhanced Infrared Satellite Imagery.  

National Technical Information Service (NTIS)

A procedure to locate tropical cyclone centers with Enhanced Infrared (EIR) satellite imagery is presented. Schematic representations of cloud pattern centers are shown along with EIR examples to help the user select the most likely center position for an...

J. Jiang, V. F. Dvorak

1987-01-01

59

The increasing intensity of the strongest tropical cyclones.  

PubMed

Atlantic tropical cyclones are getting stronger on average, with a 30-year trend that has been related to an increase in ocean temperatures over the Atlantic Ocean and elsewhere. Over the rest of the tropics, however, possible trends in tropical cyclone intensity are less obvious, owing to the unreliability and incompleteness of the observational record and to a restricted focus, in previous trend analyses, on changes in average intensity. Here we overcome these two limitations by examining trends in the upper quantiles of per-cyclone maximum wind speeds (that is, the maximum intensities that cyclones achieve during their lifetimes), estimated from homogeneous data derived from an archive of satellite records. We find significant upward trends for wind speed quantiles above the 70th percentile, with trends as high as 0.3 +/- 0.09 m s(-1) yr(-1) (s.e.) for the strongest cyclones. We note separate upward trends in the estimated lifetime-maximum wind speeds of the very strongest tropical cyclones (99th percentile) over each ocean basin, with the largest increase at this quantile occurring over the North Atlantic, although not all basins show statistically significant increases. Our results are qualitatively consistent with the hypothesis that as the seas warm, the ocean has more energy to convert to tropical cyclone wind. PMID:18769438

Elsner, James B; Kossin, James P; Jagger, Thomas H

2008-09-01

60

The Effect of the Ocean Eddy on Tropical Cyclone Intensity  

Microsoft Academic Search

The rapid intensification of Hurricane Katrina followed by the devastation of the U.S. Gulf States highlights the critical role played by an upper-oceanic thermal structure (such as the ocean eddy or Loop Current) in affecting the development of tropical cyclones. In this paper, the impact of the ocean eddy on tropical cyclone intensity is investigated using a simple hurricane-ocean coupled

Chun-Chieh Wu; Chia-Ying Lee; I.-I. Lin

2007-01-01

61

Importance of tropical cyclone heat potential for tropical cyclone intensity and intensification in the Western North Pacific  

Microsoft Academic Search

Which is more important for tropical cyclone (TC) intensity and intensification, sea surface temperature (SST) or tropical\\u000a cyclone heat potential (TCHP)? Investigations using best-track TC central pressures, TRMM\\/TMI three-day mean SST data, and\\u000a an estimated TCHP based on oceanic reanalysis data from 1998 to 2004, show that the central pressure is more closely related\\u000a to TCHP accumulated from TC formation

Akiyoshi Wada; Norihisa Usui

2007-01-01

62

High resolution numerical simulation of Tropical Cyclone Drena undergoing extra-tropical transition  

Microsoft Academic Search

Summary Tropical Cyclone Drena, a relatively long lived cyclone lasting from January 2, 1997 to January 10, 1997, crossed over three well separated island groups and affected a fourth in the south western Pacific Ocean during different stages of its life cycle. Midway through its transition into an extra-tropical low, it passed over the eastern edge of Norfolk Island, an

B. W. Buckley; L. M. Leslie

1998-01-01

63

2012 Atlantic Tropical Cyclone Outlook , Morgan Lennon2  

E-print Network

(AMM), Atlantic Multidecadal Oscillation (AMO), Atlantic Warm Pool (AWP), Dipole Mode (DM), Tropical2012 Atlantic Tropical Cyclone Outlook Lian Xie1 , Morgan Lennon2 , and Montserrat Fuentes2 University Summary of 2012 Forecast Results The 2012 Atlantic** hurricane season is forecast to be on par

Parker, Matthew D. Brown

64

Overshooting convection in tropical cyclones David M. Romps1  

E-print Network

2009; revised 17 March 2009; accepted 8 April 2009; published 6 May 2009. [1] Using infrared satellite imagery, best-track data, and reanalysis data, tropical cyclones are shown to contain a disproportionate of stratospheric water vapor. It is the objective of this study to quantify the fraction of tropical overshooting

Romps, David M.

65

Research Spotlight: Tropical cyclone formation affected by ocean color  

NASA Astrophysics Data System (ADS)

The color of the ocean can alter the frequency of tropical cyclones, according to a new study. The absorption of sunlight is affected by the concentration of chlorophyll, with the Sun's heat penetrating deeper in clear, low-chlorophyll waters. In the ocean gyres this heat can get carried away so that lower concentrations of chlorophyll are associated with colder surface waters. Ocean surface temperatures can affect atmospheric circulation patterns and thus the formation of cyclones and other weather patterns.

Tretkoff, Ernie

66

Interactions Between Vestige Atlantic Tropical Cyclones and Mid-latitude Cyclonic Storms Over Mediterranean Basin  

NASA Astrophysics Data System (ADS)

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 western 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 (jet 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, Lorenzo 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 the 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.

Smith, E. A.; Mehta, A. V.; Mugnai, A.; Tripoli, G. J.

2006-12-01

67

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

E-print Network

of global warming on tropical cyclones. climate change | natural hazards Some 90 tropical cyclones develop of these additional factors to global climate change generally results in a reduction of the global frequency of tropical cyclones as the climate warms, seen in many explicit and downscaled simulations using global

Rothman, Daniel

68

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

E-print Network

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

Li, Tim

69

Predictability of Tropical Cyclones Using the ECMWF Ensemble Prediction System  

NASA Astrophysics Data System (ADS)

The predictability of tropical cyclones using the ECMWF ensemble prediction system (EPS) is demonstrated with 3 severe cyclones in the Indian Ocean and 1 supertyphoon from the northwest Pacific, which include: Gonu, Sidr, and Man-Yi from 2007 and Nargis from 2008. While TC genesis forecasts are assumed to have little skill beyond 48 hours, we show that these projections can provide considerable lead-time with the ECMWF ensembles on average, correctly projecting the date of genesis and location of TC formation 5.5 days in advance. In addition, the ECMWF EPS shows considerable skill in track forecasts for both timing and location of movement especially in the 7 to 10 day range for all four tropical cyclones. While TC intensity forecasts are generally underestimated - attributed to the reduced resolution in the ECMWF ensembles - these intensity projections, especially for large tropical cyclones, can provide several days of additional lead-time that is not currently provided. This extra lead-time is vitally important in countries where coastal evacuations and disaster preparations are particularly slow. The potential forecasting benefits using the ECMWF EPS for tropical cyclones is reviewed in conjunction with a separate presentation in how this information can be used to mitigate disaster risk for countries in coastal areas of the Northern Indian Ocean.

Belanger, J. I.; Webster, P. J.; Hoyos, C. H.; Curry, J. A.; Agudelo, P. A.

2008-12-01

70

Field theoretical prediction of a property of the tropical cyclone  

NASA Astrophysics Data System (ADS)

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.

Spineanu, F.; Vlad, M.

2014-01-01

71

Reconstructing a Partially Observed Record of Tropical Cyclone Counts.  

NASA Astrophysics Data System (ADS)

An approach to reconstructing a partially observed annual time series of tropical cyclone counts is presented. The approach is based on a simple model of the time series of true counts and on a simple model of the way in which this time series is observed through time. The approach is applied to a record of observed tropical cyclone counts for the Australian region for the period 1910-88. Some diagnostics are presented that indicate the model performs fairly well at reproducing the behavior of the observed counts.

Solow, Andrew R.

1989-11-01

72

Contributions of Tropical Cyclones to the North Atlantic Climatological Rainfall as Observed from Satellites  

NASA Technical Reports Server (NTRS)

The tropical cyclone rainfall climatology study that was performed for the North Pacific was extended to the North Atlantic. Similar to the North Pacific tropical cyclone study, mean monthly rainfall within 444 km of the center of the North Atlantic tropical cyclones (i.e., that reached storm stage and greater) was estimated from passive microwave satellite observations during, an eleven year period. These satellite-observed rainfall estimates were used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the North Atlantic total rainfall during, June-November when tropical cyclones were most abundant. The main results from this study indicate: 1) that tropical cyclones contribute, respectively, 4%, 3%, and 4% to the western, eastern, and entire North Atlantic; 2) similar to that observed in the North Pacific, the maximum in North Atlantic tropical cyclone rainfall is approximately 5 - 10 deg poleward (depending on longitude) of the maximum non-tropical cyclone rainfall; 3) tropical cyclones contribute regionally a maximum of 30% of the total rainfall 'northeast of Puerto Rico, within a region near 15 deg N 55 deg W, and off the west coast of Africa; 4) there is no lag between the months with maximum tropical cyclone rainfall and non-tropical cyclone rainfall in the western North Atlantic, while in the eastern North Atlantic, maximum tropical cyclone rainfall precedes maximum non-tropical cyclone rainfall; 5) like the North Pacific, North Atlantic tropical cyclones Of hurricane intensity generate the greatest amount of rainfall in the higher latitudes; and 6) warm ENSO events inhibit tropical cyclone rainfall.

Rodgers, Edward B.; Adler, Robert F.; Pierce, Harold F.; Einaudi, Franco (Technical Monitor)

2000-01-01

73

Long-Term Natural Variability of Tropical Cyclones in Australia  

Microsoft Academic Search

Numerous late Holocene records of tropical cyclones have been collected from tropical northern Australia. They are in the\\u000a form of multiple shore parallel sedimentary ridges deposited over the past 6,000 years and an 800 year long annual resolution\\u000a oxygen isotope record from a calcium carbonate cave stalagmite. The sedimentary ridges are composed of coral fragments, or\\u000a shell and sand or

Jonathan Nott

74

2010 Atlantic Tropical Cyclone Outlook , Danny Modlin2  

E-print Network

from SST datasets over the region between 21S to 32N and 74W to 15E. Atlantic Multidecadal Oscillation2010 Atlantic Tropical Cyclone Outlook Lian Xie1 , Danny Modlin2 , and Montserrat Fuentes2 University Summary of 2010 Forecast Results The 2010 Atlantic hurricane season is forecast to be above normal

Liu, Paul

75

2011 Atlantic Tropical Cyclone Outlook , Morgan Lennon2  

E-print Network

://www.cdc.noaa.gov/data/climateindices/ and include Atlantic Meridional Mode (AMM), Atlantic Multidecadal Oscillation (AMO), Atlantic Warm Pool (AWP2011 Atlantic Tropical Cyclone Outlook Lian Xie1 , Morgan Lennon2 , and Montserrat Fuentes2 University Summary of 2011 Forecast Results The 2011 Atlantic hurricane season is forecast to be more active

Liu, Paul

76

Cluster Analysis of Southern Hemisphere Tropical Cyclone Tracks  

NASA Astrophysics Data System (ADS)

A probabilistic clustering method is used to describe various aspects of tropical cyclone tracks in the Southern Hemisphere, for the period 1969-2008. A total of 10 clusters are obtained, being comprised of five in the Pacific Ocean, four in the Indian Ocean, and one to the north of Australia. Clusters are explored with respect to their large-scale environmental controls, including sea surface temperature, El Niño-Southern Oscillation (ENSO), low-level vertical vorticity, deep-layer vertical wind shear, outgoing longwave radition, and the Madden-Julian Oscillation (MJO). Composite maps, constructed 2 days prior to genesis for each cluster, indicate that many of these can be seen as significant precursors to tropical cyclone formation (relative to the quiescent days with the same seasonality). In addition to large-scale controls, clusters are also evaluated in terms of their genesis location, seasonality, mean peak intensity, track duration, landfall location, and intensity at landfall. Preliminary results indicate that both ENSO and MJO play important roles in discriminating between clusters. La Niña events are associated with enhanced tropical cyclone activity in the eastern Indian Ocean (2 clusters) and Coral Sea (1 cluster), while El Niño events result in more tropical cyclones forming in two south-central Pacific clusters. The ENSO-modulating effect on genesis appears to be caused primarily by changes in low-level zonal flow near the equator, and associated relative vorticity in the main development regions.

Ramsay, H. A.; Camargo, S. J.

2010-12-01

77

Comments on "Global Climate Change and Tropical Cyclones": Part II  

E-print Network

) the inconsistency in the response of different climate models to green- house gas increases. We agree that current of the inner core oftropical cyclones. Thus, the relevant issue is whether or not the tropical vortices of whether the anticipated green- increase in maximum wind speed and a decrease in house gas-induced warming

Broccoli, Anthony J.

78

Semi-Empirical Projections of Future Atlantic Tropical Cyclone Activity  

NASA Astrophysics Data System (ADS)

Using a previously validated statistical model relating Atlantic annual tropical cyclone (TC) counts to climate state variables, we investigate the impact of projected future changes in climate on Atlantic TC activity. In contrast to some recent studies, our results suggest, albeit with a wide uncertainty range, the possibility that anthropogenic climate change could lead to a substantial increase in annual TC counts

Sabbatelli, T. A.; Mann, M. E.; Miller, S. K.; Evans, J. L.

2008-12-01

79

TROPICAL CYCLONE FORMATIONS IN THE SOUTH CHINA SEA  

Microsoft Academic Search

In the past 34 years (1972-2005), there were about one thousand tropical cyclones (TCs) formed in the western North Pacific (WNP). During the same period, 131 TCs formed in the South China Sea (SCS) with an annual average of 3.9. Almost no TC formation occurs in the SCS from January to March, but the number of TC formation cases increases

CHENG-SHANG LEE; YUNG-LAN LIN

80

Hurricane Isaac, August 28, 2012/NOAA Tropical Cyclones  

E-print Network

by destructive winds, tornadoes and flooding from these storms. How great is the danger? For 1970 be devastating. Floods from heavy rains and severe weather, such as tornadoes, can cause extensive damage can still bring heavy rain and high winds. Tropical cyclone formation regions with mean tracks/NWS Jet

81

Tropical Cyclone Movement Forecasts Based on Observations from Satellites.  

National Technical Information Service (NTIS)

A method to predict 24-hr movement of tropical cyclones using consecutive daily satellite views is described. The method is based on the observation that changes in the location of major structural features of the storm are correlated with changes in the ...

R. W. Fett, S. Brand

1974-01-01

82

A 6000 year tropical cyclone record from Western Australia  

NASA Astrophysics Data System (ADS)

This study provides the first long-term tropical cyclone record from the Indian Ocean region. Multiple shore parallel ridges composed entirely of one species of marine cockle shell ( Fragum eragatum) standing between 3 and 6 m above mean sea level occur at Hamelin Pool, Shark Bay, Western Australia. The ridges record a tropical cyclone history between approximately 500 cal BP and 6000-7000 cal BP. Numerical storm surge and shallow water wave modelling techniques have been applied to determine the intensity (central pressure with uncertainty margins) of the storms responsible for deposition of the ridges, which has occurred approximately every 190-270 years. The ridges also record a 1700 year gap in tropical cyclone activity, between approximately 5400 cal BP and 3700 cal BP, where ridges deposited prior to this time were buried by a substantial deposit of aeolian fine-grained terrestrial sediment. The presence of this sedimentary unit suggests that this 1700 year period was characterised by a very dry climate; possibly the driest phase experienced in this region since the mid-Holocene. The absence of tropical cyclones at this time and the occurrence of this mega-drought may be linked.

Nott, Jonathan

2011-03-01

83

Assessing Impacts of Global Warming on Tropical Cyclone Tracks  

Microsoft Academic Search

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 and in formation locations.It is demonstrated that the

Liguang Wu; Bin Wang

2004-01-01

84

Tropical cyclones and heavy rainfall in Fujian Province, China  

Microsoft Academic Search

Tropical cyclones (TCs) are historically documented along the coastline of China. They can have negative impacts on society and damages are reported annually. This paper examines to what extent TCs are responsible for heavy rain days (precipitation > 100 mm\\/d) in coastal Fujian Province. The average deviation of TCs making landfall in China is 25%, and they occur more reliably than TCs in

Yizhou Yin; Marco Gemmer; Yong Luo; Yan Wang

2010-01-01

85

Tropical Cyclone Parameters Derived from Synthetic Aperture Radar (SAR) Images  

Microsoft Academic Search

Ocean waves play an important role in the dynamics of extreme events like hurricanes or typhoons by conditioning the air\\/sea fluxes of momentum, heat and moisture. In this study a data set of ENVISAT ASAR Scan SAR images (400 times 400 km coverage) are used to observe the structure of tropical cyclones and typhoons at the sea surface. The following

A. Reppucci; S. Lehner; J. Schulz-Stellenfleth

2006-01-01

86

A QuikSCAT climatology of tropical cyclone size  

E-print Network

QuikSCAT data of near-surface wind vectors for the years 1999–2008 are used to create a climatology of tropical cyclone (TC) size, defined as the radius of vanishing winds. The azimuthally-averaged radius of 12 ms?1 [ms ...

Chavas, Daniel Robert

87

Tropical Cyclone Induced Air-Sea Interactions Over Oceanic Fronts  

NASA Astrophysics Data System (ADS)

Recent severe tropical cyclones underscore the inherent importance of warm background ocean fronts and their interactions with the atmospheric boundary layer. Central to the question of heat and moisture fluxes, the amount of heat available to the tropical cyclone is predicated by the initial mixed layer depth and strength of the stratification that essentially set the level of entrainment mixing at the base of the mixed layer. In oceanic regimes where the ocean mixed layers are thin, shear-induced mixing tends to cool the upper ocean to form cold wakes which reduces the air-sea fluxes. This is an example of negative feedback. By contrast, in regimes where the ocean mixed layers are deep (usually along the western part of the gyres), warm water advection by the nearly steady currents reduces the levels of turbulent mixing by shear instabilities. As these strong near-inertial shears are arrested, more heat and moisture transfers are available through the enthalpy fluxes (typically 1 to 1.5 kW m-2) into the hurricane boundary layer. When tropical cyclones move into favorable or neutral atmospheric conditions, tropical cyclones have a tendency to rapidly intensify as observed over the Gulf of Mexico during Isidore and Lili in 2002, Katrina, Rita and Wilma in 2005, Dean and Felix in 2007 in the Caribbean Sea, and Earl in 2010 just north of the Caribbean Islands. To predict these tropical cyclone deepening (as well as weakening) cycles, coupled models must have ocean models with realistic ocean conditions and accurate air-sea and vertical mixing parameterizations. Thus, to constrain these models, having complete 3-D ocean profiles juxtaposed with atmospheric profiler measurements prior, during and subsequent to passage is an absolute necessity framed within regional scale satellite derived fields.

Shay, L. K.

2012-12-01

88

Vulnerability of bangladesh to climate change and sea level rise through tropical cyclones and storm surges  

Microsoft Academic Search

Bangladesh is frequently visited by natural disasters such as tropical cyclones, storm surges, floods, droughts, tornadoes, and “norwesters.” Of these, tropical cyclones originating in the Bay of Bengal and associated storm surges are the most disastrous. There are various reasons for the disastrous effects of cyclones and storm surges in Bangladesh. Superimposed on these disastrous effects, climate change and any

A. Ali

1996-01-01

89

Growth and Decay of an Extra-Tropical Cyclone’s PV-Tower  

Microsoft Academic Search

Summary   The surface low of a mature extra-tropical cyclone is often surmounted by a troposphere-spanning column of anomalously high\\u000a potential vorticity (PV). In this study the growth and decay of such a PV-tower is traced for one major North Atlantic frontal-wave\\u000a cyclone using the ECMWF analysis fields and adopting both Eulerian and Lagrangian frameworks.\\u000a \\u000a A tower’s structure and composition relates

A. M. Rossa; H. Wernli; H. C. Davies

2000-01-01

90

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

NSDL National Science Digital Library

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.

Comet

2010-12-22

91

Tropical Cyclone Monty Strikes Western Australia  

NASA Technical Reports Server (NTRS)

The Multi-angle Imaging SpectroRadiometer (MISR) acquired these natural color images and cloud top height measurements for Monty before and after the storm made landfall over the remote Pilbara region of Western Australia, on February 29 and March 2, 2004 (shown as the left and right-hand image sets, respectively). On February 29, Monty was upgraded to category 4 cyclone status. After traveling inland about 300 kilometers to the south, the cyclonic circulation had decayed considerably, although category 3 force winds were reported on the ground. Some parts of the drought-affected Pilbara region received more than 300 millimeters of rainfall, and serious and extensive flooding has occurred.

The natural color images cover much of the same area, although the right-hand panels are offset slightly to the east. Automated stereoscopic processing of data from multiple MISR cameras was utilized to produce the cloud-top height fields. The distinctive spatial patterns of the clouds provide the necessary contrast to enable automated feature matching between images acquired at different view angles. The height retrievals are at this stage uncorrected for the effects of the high winds associated with cyclone rotation. Areas where heights could not be retrieved are shown in dark gray.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. These data products were generated from a portion of the imagery acquired during Terra orbits 22335 and 22364. The panels cover an area of about 380 kilometers x 985 kilometers, and utilize data from blocks 105 to 111 within World Reference System-2 paths 115 and 113.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2004-01-01

92

A field theoretical prediction of the tropical cyclone properties  

E-print Network

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

Spineanu, Florin

2013-01-01

93

Atlantic tropical cyclones in the twentieth century: natural variability and secular change in cyclone count  

Microsoft Academic Search

The twentieth century record of the annual count of Atlantic tropical cyclones (TCs) is analyzed to develop consistent estimates\\u000a of its natural variability and secular change components. The analysis scheme permits development of multidecadal trends from\\u000a natural variability alone, reducing aliasing of the variability and change components. The scheme is rooted in recurrent variability\\u000a modes of the influential SST field

Sumant Nigam; Bin Guan

2011-01-01

94

Recent Advances in Understanding Tropical Cyclone-Climate Interactions Using Climate Models of Varying Complexity  

NASA Astrophysics Data System (ADS)

Understanding potential feedbacks associated with tropical cyclones in the coupled ocean-atmosphere system is important within the context of climate change. Here we present results from recent ocean/atmosphere modeling studies addressing the role of tropical cyclones within the climate system. We use multiple models featuring varying levels of complexity, and we simulate the effects of tropical cyclones in several ways. This includes modifying the ocean's vertical mixing budget and surface wind fields to reflect conditions consistent with present-day tropical cyclone activity, as well as for altered climate states. We find tropical cyclones can significantly alter the thermal structure of the upper ocean in the tropical and subtropical latitudes, and these changes affect the dynamics of the subtropical overturning circulation. Effects are enhanced for climate scenarios with amplified tropical cyclone activity. Furthermore, altered sea surface temperatures directly impact the strength and spatial extent of large scale atmospheric circulations such as the Hadley and Walker cells. We find tropical cyclones do not significantly influence the equator to pole oceanic heat transport for present-day conditions. Results point to the possibility of tropical cyclone-induced climate feedbacks, however, these feedbacks are significant only for scenarios with increased tropical cyclone activity compared to the current climatology.

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

2010-12-01

95

Effects of Environmental Flow upon Tropical Cyclone Structure  

Microsoft Academic Search

Numerical simulations of tropical-cyclone-like vortices are performed to analyze the effects of unidirectional vertical wind shear and translational flow upon the organization of convection within a hurricane's core region and upon the intensity of the storm. A series of dry and moist simulations is performed using the Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model version 5 (MM5) with

William M. Frank; Elizabeth A. Ritchie

1999-01-01

96

Satellite-observed latent heat release in a tropical cyclone  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

97

Disaster triggers disaster: Earthquake triggering by tropical cyclones  

NASA Astrophysics Data System (ADS)

Three recent devastating earthquakes, the 1999 M=7.6 Chi-Chi (Taiwan), 2010 M=7.0 Leogane (Haiti), 2010 M=6.4 Kaohsiung (Taiwan), and additional three moderate size earthquakes (6tropical mountainous areas shortly after very wet tropical cyclones (hurricane or typhoon) hit the very same area. The most familiar example is Haiti, which was hit during the late summer of 2008 by two hurricanes and two tropical storms (Fay, Gustav, Hanna and Ike) within 25 days. A year an a half after this very wet hurricane season, the 2010 Leogane earthquake occurred in the mountainous Haiti's southern peninsula and caused the death of more than 300,000 people. The other cases are from Taiwan, which is characterized by a high seismicity level and frequent typhoon landfall. The three wettest typhoons in Taiwan's past 50 years were Morakot (in 2009, with 2885 mm or rain), Flossie (1969, 2162 mm) and Herb (1996, 1987 mm)[Lin et al., 2010]. Each of this three very wet storms was followed by one or two main-shock M>6 earthquake that occurred in the central mountainous area of Taiwan within three years after the typhoon. The 2009 Morakot typhoon was followed by 2009 M=6.2 Nantou and 2010 M=6.4 Kaohsiung earthquakes; the 1969 Flossie typhoon was followed by an M=6.3 earthquake in 1972; and the 1996 Herb typhoon by the 1998 M=6.2 Rueyli and 1999 M=7.6 Chi-Chi earthquakes. The earthquake catalog of Taiwan lists only two other M>6 main-shocks that occurred in Taiwan's central mountainous belt, one of them was in 1964 only four months after the wet Typhoon Gloria poured heavy rain in the same area. We suggest that the close proximity in time and space between wet tropical cyclones and earthquakes reflects a physical link between the two hazard types in which these earthquakes were triggered by rapid erosion induced by tropical cyclone's heavy rain. Based on remote sensing observations, meshfree finite element modeling, and Coulomb failure stress analysis, we show that the erosion induced by very wet cyclones increased the failure stresses at the hypocenters' depth by 300-1500 Pa, which ultimately triggered these earthquakes. Our findings are supported by a statistical analysis indicating a very low probability (1-5%) for a random earthquake occurrence process to form the observed typhoon-earthquake temporal distribution.

Wdowinski, S.; Tsukanov, I.

2011-12-01

98

Buoyancy in tropical cyclones and other rapidly rotating atmospheric vortices  

NASA Astrophysics Data System (ADS)

Motivated primarily by its application to understanding tropical-cyclone intensification and maintenance, we re-examine the concept of buoyancy in rapidly rotating vortices, distinguishing between the buoyancy of the symmetric balanced vortex or system buoyancy, and the local buoyancy associated with cloud dynamics. The conventional definition of buoyancy is contrasted with a generalized form applicable to a vortex, which has a radial as well as a vertical component. If, for the special case of axisymmetric motions, the balanced density and pressure distribution of a rapidly rotating vortex are used as the reference state, the buoyancy field then characterizes the unbalanced density perturbations, i.e. the local buoyancy. We show how to determine such a reference state without approximation. The generation of the toroidal circulation of a vortex, which is necessary for vortex amplification, is characterized in the vorticity equation by the baroclinicity vector. This vector depends, inter-alia, on the horizontal (or radial) gradient of buoyancy evaluated along isobaric surfaces. We show that for a tropical-cyclone-scale vortex, the buoyancy so calculated is significantly different from that calculated at constant height or on surfaces of constant ? ( ? = ( p - p*)/( ps - p*), where p is the actual pressure, p* some reference pressure and ps is the surface pressure). Since many tropical-cyclone models are formulated using ?-coordinates, we examine the calculation of buoyancy on ?-surfaces and derive an expression for the baroclinicity vector in ?-coordinates. The baroclinic forcing term in the azimuthal vorticity equation for an axisymmetric vortex is shown to be approximately equal to the azimuthal component of the curl of the generalized buoyancy. A scale analysis indicates that the vertical gradient of the radial component of generalized buoyancy makes a comparatively small contribution to the generation of toroidal vorticity in a tropical cyclone, but may be important in tornadoes and possibly also in dust devils. We derive also a form of the Sawyer-Eliassen equation from which the toroidal (or secondary) circulation of a balanced vortex may be determined. The equation is shown to be the time derivative of the toroidal vorticity equation in which the time rate-of-change of the material derivative of potential toroidal vorticity is set to zero. In analogy with the general case, the diabatic forcing term in the Sawyer-Eliassen equation is shown to be approximately equal to the time rate-of-change of the azimuthal component of the curl of generalized buoyancy. Finally, we discuss the generation of buoyancy in tropical cyclones and contrast the definitions of buoyancy that have been used in recent studies of tropical cyclones. We emphasize the non-uniqueness of the buoyancy force, which depends on the choice of a reference density and pressure, and note that different, but equivalent interpretations of the flow dynamics may be expected to arise if different reference quantities are chosen.

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

2005-07-01

99

The World Wide Lightning Location Network and Convective Activity in Tropical Cyclones  

E-print Network

The World Wide Lightning Location Network and Convective Activity in Tropical Cyclones SERGIO F February 2010, in final form 19 August 2010) ABSTRACT Lightning flash density in tropical cyclones (TCs) is investigated to identify whether lightning flashes provide information on TC intensity and/or intensity change

Corbosiero, Kristen L.

100

Distinguishing Tropical Cyclone-Related Flooding in U.S. Presidential Disaster Declarations: 19651997  

E-print Network

Distinguishing Tropical Cyclone-Related Flooding in U.S. Presidential Disaster Declarations: 1965 disasters related to flooding resulting from tropical cyclones. Neither FEMA nor the states that request federal disaster aid distin- guish flood disasters by their meteorological origin, making it difficult

Colorado at Boulder, University of

101

Climate Forcing of North Atlantic Tropical Cyclone Activity over the last 6000 years  

Microsoft Academic Search

Reconstructions of extreme overwash events in backbarrier lagoons and wetlands from the Caribbean to the northeastern United States show similar patterns of event occurrence. Comparisons with instrumental and historical records indicate that most of these overwash layers were likely deposited by landfalling tropical cyclones. Over the last 6000 years intense tropical cyclones have deposited coarse grained laminae in a coastal

J. P. Donnelly; J. D. Woodruff; E. Scileppi

2006-01-01

102

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

103

Use of a Genesis Potential Index to Diagnose ENSO Effects on Tropical Cyclone Genesis  

E-print Network

Use of a Genesis Potential Index to Diagnose ENSO Effects on Tropical Cyclone Genesis SUZANA J, and relative humidity and vorticity are important for the eastward shift in the mean genesis location in developing schemes for forecasting tropical cyclone (TC) number, to the extent that an independent capability

Sobel, Adam

104

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

Microsoft Academic Search

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

James B. Elsner; Bethany Kocher

2000-01-01

105

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

E-print Network

: Wind turbine classes as defined in IEC-61400-1 [1] History shows that tropical cyclones can cause with tropical cyclones. Present international design codes for wind turbines do not apply to these regions. A 30 safety factor is 1.35. The wind turbine yawing controls were found to be able to cope with the demands

106

Analysis of North Atlantic Tropical Cyclone Intensify Change Using Data Mining  

ERIC Educational Resources Information Center

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…

Tang, Jiang

2010-01-01

107

Statistical Tropical Cyclone Wind Radii Prediction Using Climatology and Persistence JOHN A. KNAFF  

E-print Network

Statistical Tropical Cyclone Wind Radii Prediction Using Climatology and Persistence JOHN A. KNAFF. The statistical-parametric model employs aspects of climatology and persis- tence to forecast tropical cyclone employs climatology and persistence suggests that the statistical-parametric model does a good job

Collett Jr., Jeffrey L.

108

Low frequency variability of tropical cyclone potential intensity 2. Climatology for 19821995  

E-print Network

Low frequency variability of tropical cyclone potential intensity 2. Climatology for 1982 2002. [1] In this note, we describe the method of calculating a climatology of tropical cyclone/pcmin/climo.html. The climatology has been constructed from the National Centers for Environmental Prediction/National Center

Emanuel, Kerry A.

109

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

Microsoft Academic Search

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.

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

2009-01-01

110

A note concerning the Lighthill “sandwich model” of tropical cyclones  

PubMed Central

The basic element of Lighthill's “sandwich model” of tropical cyclones is the existence of “ocean spray,” a layer intermediate between air and sea made up of a cloud of droplets that can be viewed as a “third fluid.” We propose a mathematical model of the flow in the ocean spray based on a semiempirical turbulence theory and demonstrate that the availability of the ocean spray over the waves in the ocean can explain the tremendous acceleration of the wind as a consequence of the reduction of the turbulence intensity by droplets. This explanation complements the thermodynamic arguments proposed by Lighthill. PMID:16049097

Barenblatt, G. I.; Chorin, A. J.; Prostokishin, V. M.

2005-01-01

111

Classic Maya civilization collapse associated with reduction in tropical cyclone activity  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

112

The structure and rainfall features of Tropical Cyclone Rammasun (2002)  

NASA Astrophysics Data System (ADS)

Tropical Rainfall Measuring Mission (TRMM) data [TRMM Microwave Imager/Precipitation Radar/Visible and Infrared Scanner (TMI/PR/VIRS)] and a numerical model are used to investigate the structure and rainfall features of Tropical Cyclone (TC) Rammasun (2002). Based on the analysis of TRMM data, which are diagnosed together with NCEP/AVN [Aviation (global model)] analysis data, some typical features of TC structure and rainfall are preliminary discovered. Since the limitations of TRMM data are considered for their time resolution and coverage, the world observed by TRMM at several moments cannot be taken as the representation of the whole period of the TC lifecycle, therefore the picture should be reproduced by a numerical model of high quality. To better understand the structure and rainfall features of TC Rammasun, a numerical simulation is carried out with mesoscale model MM5 in which the validations have been made with the data of TRMM and NCEP/AVN analysis.

Ma, Leiming; Duan, Yihong; Zhu, Yongti

2004-12-01

113

Increasing destructiveness of tropical cyclones over the past 30 years.  

PubMed

Theory and modelling predict that hurricane intensity should increase with increasing global mean temperatures, but work on the detection of trends in hurricane activity has focused mostly on their frequency and shows no trend. Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and--taking into account an increasing coastal population--a substantial increase in hurricane-related losses in the twenty-first century. PMID:16056221

Emanuel, Kerry

2005-08-01

114

Sea surface signature of tropical cyclones using microwave remote sensing  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

115

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

NASA Technical Reports Server (NTRS)

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.

Wilson, Robert M.

2011-01-01

116

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

PubMed Central

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

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

2011-01-01

117

North Atlantic Basin Tropical Cyclone Activity in Relation to Temperature and Decadal- Length Oscillation Patterns  

NASA Technical Reports Server (NTRS)

Yearly frequencies of North Atlantic basin tropical cyclones, their locations of origin, peak wind speeds, average peak wind speeds, lowest pressures, and average lowest pressures for the interval 1950-2008 are examined. The effects of El Nino and La Nina on the tropical cyclone parametric values are investigated. Yearly and 10-year moving average (10-yma) values of tropical cyclone parameters are compared against those of temperature and decadal-length oscillation, employing both linear and bi-variate analysis, and first differences in the 10-yma are determined. Discussion of the 2009 North Atlantic basin hurricane season, updating earlier results, is given.

Wilson, Robert M.

2009-01-01

118

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

E-print Network

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.

Poh, Chung-Kiak

2014-01-01

119

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

E-print Network

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. ...

Sobel, Adam

120

Global Losses and Declining Vulnerability to Tropical Cyclones  

NASA Astrophysics Data System (ADS)

Approach An extreme environmental event may generate different losses for different societies. If the physical exposure to an event is held fixed, then the magnitude of a society's loss defines its vulnerability to that event. Competing hypotheses suggest that social and economic developments could make vulnerability rise or fall over time, but previous studies have been unable to reject either hypothesis because they lacked accurate data on societies' physical exposure to extreme events. We address this problem for a specific type of event by reconstructing the exposure of 233 countries to every tropical cyclone (TC) on the planet between 1950 and 2008 in making use of the Limited Information Cyclone Reconstruction and Integration for Climate and Economics (LICRICE) model [Hsiang, 2010]. By filling a critical data gap, this reconstruction enables us to compare how revenue losses, damages, and deaths from physically similar events change over time. Our approach contrasts with a large literature, which relies almost exclusively on self-reporting data of TC damages compiled by the Emergency Events Database (EM-DAT)[OFDA/CRED, 2009]. Results On a global scale, we find that populations rapidly mitigate certain TC risks, reducing their reported damages from a TC of low intensity by a remarkable 9.4% yr-1 and death rates by 5.1% yr-1 (Figure 1). However, these rapid reductions in vulnerability are not evident for the highest intensity TCs and lost agricultural revenues, which are more difficult to observe than deaths or damages, exhibit non-declining vulnerability for events of all intensities. Because the vulnerability of agriculture has remained high while vulnerability to damages has declined rapidly, our results indicate that lost agricultural revenues have dominated TC losses ever since ˜1990. References Hsiang, S. M. (2010). Temperatures and cyclones strongly associated with economic production in the Caribbean and Central America. Proceedings of the National Academy of Sciences, 107(35):15367-15372. OFDA/CRED (2009). The International Disaster Database.

Narita, D.; Hsiang, S. M.

2011-12-01

121

Ocean feedback to tropical cyclones: climatology and processes  

NASA Astrophysics Data System (ADS)

This study presents the first multidecadal and coupled regional simulation of cyclonic activity in the South Pacific. The long-term integration of state-of the art models provides reliable statistics, missing in usual event studies, of air-sea coupling processes controlling tropical cyclone (TC) intensity. The coupling effect is analyzed through comparison of the coupled model with a companion forced experiment. Cyclogenesis patterns in the coupled model are closer to observations with reduced cyclogenesis in the Coral Sea. This provides novel evidence of air-sea coupling impacting not only intensity but also spatial cyclogenesis distribution. Storm-induced cooling and consequent negative feedback is stronger for regions of shallow mixed layers and thin or absent barrier layers as in the Coral Sea. The statistical effect of oceanic mesoscale eddies on TC intensity (crossing over them 20 % of the time) is also evidenced. Anticyclonic eddies provide an insulating effect against storm-induced upwelling and mixing and appear to reduce sea surface temperature (SST) cooling. Cyclonic eddies on the contrary tend to promote strong cooling, particularly through storm-induced upwelling. Air-sea coupling is shown to have a significant role on the intensification process but the sensitivity of TCs to SST cooling is nonlinear and generally lower than predicted by thermodynamic theories: about 15 rather than over 30 hPa °C-1 and only for strong cooling. The reason is that the cooling effect is not instantaneous but accumulated over time within the TC inner-core. These results thus contradict the classical evaporation-wind feedback process as being essential to intensification and rather emphasize the role of macro-scale dynamics.

Jullien, Swen; Marchesiello, Patrick; Menkes, Christophe E.; Lefèvre, Jérôme; Jourdain, Nicolas C.; Samson, Guillaume; Lengaigne, Matthieu

2014-11-01

122

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

123

A Study of Cyclones and Anti-Cyclones in Jupiter's North Tropical Zone, 2003-2013  

NASA Astrophysics Data System (ADS)

We have examined ground and space-based data from Jupiter's Northern Equatorial Belt and North Tropical Zone to characterize drift rates and statistics of cyclones and anti-cyclones. Ground-based positional data on the storms comes from the JUPOS database, maintained by the JUPOS team. Over 2,000 observations of 80 storms in the 2003-2013 time period were used to characterize trends in both latitudinal and longitudinal position, and velocity over time. We found that after the year of 2009, the dark storms in the 15-16N latitude band were forming further south than before. We hypothesize that small changes in the differential zonal wind caused this new, southerly zone to be favored. Because these storms form in an area of lower zonal wind speed, they also drift at a slower velocity relative to system III. Additionally, By comparing our analysis of JUPOS observations to Hubble and Cassini measurements of wind speed, we were able to characterize the relationship between storm size and storm velocity and a fraction of the zonal flow, and build an empirical model useful for predicting jovian storms in the future.

Penprase, Bryan E.; Marsh, Franklin M.

2014-11-01

124

Arabian Sea tropical cyclones intensified by emissions of black carbon and other aerosols.  

PubMed

Throughout the year, average sea surface temperatures in the Arabian Sea are warm enough to support the development of tropical cyclones, but the atmospheric monsoon circulation and associated strong vertical wind shear limits cyclone development and intensification, only permitting a pre-monsoon and post-monsoon period for cyclogenesis. Thus a recent increase in the intensity of tropical cyclones over the northern Indian Ocean is thought to be related to the weakening of the climatological vertical wind shear. At the same time, anthropogenic emissions of aerosols have increased sixfold since the 1930s, leading to a weakening of the southwesterly lower-level and easterly upper-level winds that define the monsoonal circulation over the Arabian Sea. In principle, this aerosol-driven circulation modification could affect tropical cyclone intensity over the Arabian Sea, but so far no such linkage has been shown. Here we report an increase in the intensity of pre-monsoon Arabian Sea tropical cyclones during the period 1979-2010, and show that this change in storm strength is a consequence of a simultaneous upward trend in anthropogenic black carbon and sulphate emissions. We use a combination of observational, reanalysis and model data to demonstrate that the anomalous circulation, which is radiatively forced by these anthropogenic aerosols, reduces the basin-wide vertical wind shear, creating an environment more favourable for tropical cyclone intensification. Because most Arabian Sea tropical cyclones make landfall, our results suggest an additional impact on human health from regional air pollution. PMID:22051678

Evan, Amato T; Kossin, James P; Chung, Chul Eddy; Ramanathan, V

2011-11-01

125

Differential leaflet mortality may influence biogeochemical cycling following tropical cyclones  

PubMed Central

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

Marler, Thomas E; Ferreras, Ulysses

2014-01-01

126

Differential leaflet mortality may influence biogeochemical cycling following tropical cyclones.  

PubMed

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

Marler, Thomas E; Ferreras, Ulysses

2014-01-01

127

Jason Tracks Powerful Tropical Cyclone Gonu's High Winds, Waves  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Wind Speed Wave Height Click on images for larger versions

This pair of images from the radar altimeter instrument on the U.S./France Jason mission reveals information on wind speeds and wave heights of Tropical Cyclone Gonu, which reached Category 5 strength in the Arabian Sea prior to landfall in early June 2007. Strong winds near 20 meters per second and wave heights of greater than 5 meters were recorded. These high waves are extremely rare in the Arabian Sea and exacerbated heavy flooding from the storm surge over much of the Oman coastline.

The U.S. portion of the Jason mission is managed by JPL for NASA's Science Mission Directorate, Washington, D.C. Research on Earth's oceans using Jason and other space-based capabilities is conducted by NASA's Science Mission Directorate to better understand and protect our home planet.

2007-01-01

128

A numerical investigation of supercells in landfalling tropical cyclones  

NASA Astrophysics Data System (ADS)

Supercell thunderstorms are known to occur in the outer rainbands of tropical cyclones (TCs), and these cells are of interest because they are occasionally tornadic. A series of multi-scale quasi-idealized TC simulations are used to study the development of outer rainband supercells. Within the environment of landfalling TCs, the sea-to-land transition of the rainbands is found to locally benefit supercell development onshore due in part to (1) enhanced surface-based destabilization during the day and (2) increased surface friction slowing and backing the low-level winds. Landfall time of day is shown to have a substantial impact on the average number, strength, and lifetime of the ensemble of simulated supercells. These idealized simulations represent a first attempt at controlled hypothesis tests for supercell and tornado ingredients within the context of a highly resolved parent TC.

Morin, M. J.; Parker, M. D.

2011-05-01

129

Can existing climate models be used to study anthropogenic changes in tropical cyclone climate?  

Microsoft Academic Search

The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While the model resolution is insufficient to reproduce

A. J. Broccoli; S. Manabe

1990-01-01

130

The Relationship between the Southern Oscillation and Tropical Cyclone Frequency in the Australian Region.  

NASA Astrophysics Data System (ADS)

A statistical model of the relationship between tropical cyclone frequency in the Australian region and an index of the strength and phase of the southern oscillation is developed for the period 1910-88. The modeling is nonstandard because the cyclone record is incomplete early in this period. The fitted model indicates that the mean annual number of cyclones during a major cold event is twice that during a major warm event.

Solow, Andrew; Nicholls, Neville

1990-10-01

131

Tropical cyclone cooling combats region-wide coral bleaching.  

PubMed

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

Carrigan, Adam D; Puotinen, Marji

2014-05-01

132

The probability of tropical cyclone landfalls in Western North Pacific  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

133

The genesis of tropical cyclone Bilis (2000) associated with cross-equatorial surges  

NASA Astrophysics Data System (ADS)

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

Xu, Yamei

2011-05-01

134

The Impact of Dry Saharan Air on Tropical Cyclone Intensification  

NASA Technical Reports Server (NTRS)

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.

Braun, Scott A.

2012-01-01

135

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

136

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

E-print Network

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 ...

Langousis, Andreas, 1981-

2009-01-01

137

Toward improved tropical cyclone intensity forecasts : probabilistic prediction, predictability, and the role of verification  

E-print Network

Over the past two decades, deterministic predictions of tropical cyclone (TC) intensity consistently scored poorly in mean absolute error (MAE) verification, despite the concurrent advancement of TC modeling and observing ...

Moskaitis, Jonathan Robert

2009-01-01

138

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

E-print Network

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 ...

Klima, Kelly

139

The tropical cyclone-induced flux of carbon between the ocean and the atmosphere  

E-print Network

Tropical cyclones are known to cause phytoplankton blooms in regions of the ocean that would otherwise support very little life; it is also known that these storms entrain carbon-rich deep water, which can cause ...

Zimmerman, Neil L

2012-01-01

140

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

E-print Network

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 ...

Woodruff, Jonathan Dalrymple

2009-01-01

141

Long-term rainfall risk from tropical cyclones in coastal areas  

E-print Network

We develop a methodology for the frequency of extreme rainfall intensities caused by tropical cyclones (TCs) in coastal areas. The model does not account for landfall effects. This makes the developed framework best suited ...

Veneziano, Daniele

142

On the Influences of Vertical Wind Shear on Symmetric Tropical Cyclone Structure Derived from AMSU  

Microsoft Academic Search

Axisymmetric temperatures and gradient-balanced winds associated with tropical cyclones derived from the Advanced Microwave Sounding Unit are stratified by the 24-h averaged vector difference of the horizontal wind between 200 and 850 hPa (or vertical wind shear). Using 186 total cases that are limited to tropical cyclones with intensities greater than 33 m s 21 (or mature) and are located

John A. Knaff; Stacey A. Seseske; Mark DeMaria; Julie L. Demuth

2004-01-01

143

Multi-model GCM ensemble simulations of idealized tropical cyclones  

NASA Astrophysics Data System (ADS)

As General Circulation Models (GCMs) are now capable of running operationally at higher horizontal resolutions than ever before, such models have become a tool of choice for the evaluation of tropical cyclones in current and future climate conditions. GCM horizontal resolutions in the range between 10-50 km are now computationally achievable for seasonal or multi-year simulations and there is growing confidence that high-resolution global models provide reliable representations of many characteristics of tropical storms. However, model design choices are an important source of uncertainty. This is widely documented for physical parameterization suites, but it is less recognized for the dynamical component of models and the physics-dynamics coupling. The study offers a first look into these structural uncertainties. This study focuses on dynamical core model intercomparisons. In particular, it looks at the results of the Dynamical Core Model Intercomparison Project (DCMIP) that took place at the National Center for Atmospheric Research (NCAR) in August 2012. The analysis is focused on the evaluation of an idealized tropical storm and uncertainties triggered by the choice of model dynamical core formulation in various global models. These models include the four dynamical cores available in NCAR's Community Atmosphere Model (Finite-Volume (FV), Spectral-Element (SE) and the Eulerian and semi-Lagrangian spectral transform dynamical cores), the NOAA model FIM, the model ICON (Max-Planck Institute and German Weather Service), GFDL's FV3 model on the cubed-sphere grid, ECMWF's Integrated Forecasting System (IFS) and the model PUMA from the University of Hamburg.

Reed, K. A.; Jablonowski, C.; Ullrich, P. A.; Kent, J.; Lauritzen, P. H.; Taylor, M.; Nair, R.

2013-12-01

144

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

NASA Astrophysics Data System (ADS)

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 of concept exercise we focus on the West Pacific region: Japan, China and South-East Asia. A database of tropical cyclone tracks is extracted from over 200 years of current climate simulations by HiGEM1.1, a high resolution, coupled ocean-atmosphere Global Climate Model. A bias correction procedure is applied to model the central pressure of the dynamically HiGEM-simulated tropical cyclones in terms of the observed (IBTrACS) distribution of central pressures. The bias-corrected storm track database is statistically sampled and spatially perturbed to produce a 1000 year database of synthetic storms. The proposed approach has several advantages: 1. it is based on a long-term, globally consistent source of dynamically simulated tropical storms under current state of the atmosphere/climate; this compensates reliance on limited and/or inconsistent historical data and provides a much larger sampling for the distribution of the tropical cyclone landfalls; 2. it allows assessment of how large scale natural climate variability may influence regional tropical cyclone activity on multidecadal time scales, and how this may alter risk; 3. it allows to analyse teleconnections in weather extremes, and hence potential accumulation of seemingly unrelated risk; 4. it can be further developed to assess how climate change may affect tropical cyclone risk in the future. Adopting an integrated approach may begin to change the way that weather related risk is understood and assessed in the insurance industry.

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

2010-05-01

145

Tree-ring Oxygen Isotope Records of Climate Modes Influencing North Atlantic Tropical Cyclone Activity  

NASA Astrophysics Data System (ADS)

The relatively short instrumental record hinders our ability to discern the linkages between low frequency modes of climate variability and tropical cyclone activity and to differentiate natural versus anthropogenic components of these trends. The development of biological proxies for tropical cyclone activity and climate provides a basis for evaluation of these linkages over much longer time frames. The oxygen isotope composition of tree-ring cellulose, sampled at high resolution (seasonal or better), provides a new proxy for tropical cyclone activity that preserves a concurrent isotope time series reflecting the influence of climate variability. This proxy archive potentially extends many centuries beyond the instrumental and historical (documentary) record of climate and tropical cyclone activity. Isotope time series for longleaf pines (Pinus palustris Mill.) in southern Georgia and South Carolina preserve distinct tropical cyclone histories, yet similar, long term trends in cellulose ? 18O compositions. The isotope time series correlate to various climate modes proposed to impact hurricane formation and frequency. Tree-ring cellulose ? 18O values at the Georgia study site show a significant negative correlation with AMO indices from 1875 to about 1950, and a weaker, positive correlation from about 1965 to 1990. The "crossover" parallels a change in the predominant ontogeny of North Atlantic tropical cyclones from tropical-only to baroclinically-enhanced hurricanes. The intervening 1950s is marked by greater correspondence to ENSO indices. Reduced seasonality in the isotope record (i.e., the difference between earlywood and latewood ? 18O values) corresponds to warm phases of the PDO. An isotope series for 1580 to 1650 suggests little tropical cyclone activity coinciding with a period (1560-1625) of severe drought in the African Sahel. Although preliminary, these results suggest that tree-ring oxygen isotope compositions are sensitive to changes in climate modes that affect hurricane frequency and may ultimately yield a long, rich archive of climate information.

Mora, C. I.; Miller, D. L.; Grissino-Mayer, H. D.; Kocis, W. N.; Lewis, D. B.

2006-12-01

146

On the incompleteness of the historical record of North Atlantic tropical cyclones  

NASA Astrophysics Data System (ADS)

There is some question as to whether the historical record of observed North Atlantic tropical cyclones prior to the advent of satellite coverage is complete. This question is central to understanding the historical trend in tropical cyclone activity and the effect of environmental factors on it. To address this question, a statistical model of the relationship between annual cyclone counts between 1870 and 2004 and sea surface temperature and the state of the Southern Oscillation is extended to allow for non-decreasing observation probability prior to 1966. The estimated observation probabilities increase from 0.72 in 1870 to 1 in 1964. Allowing for record incompleteness reduces the estimated effect of sea surface temperature on annual tropical cyclone activity.

Solow, Andrew R.; Beet, Andrew R.

2008-06-01

147

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

NASA Technical Reports Server (NTRS)

Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.

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

1981-01-01

148

The Role of Interacting Cyclones in Modifying Tropical Cyclone Landfall Threat: Fujiwhara vs. enhanced Beta drift?  

NASA Astrophysics Data System (ADS)

The recent impacts of tropical cyclones (TCs) Irene and Sandy have brought to the forefront the question of the true return period of landfalls in that region. Given the relatively short period of record of observations, those seeking robust return estimates often generate stochastic event sets. While the details of methods for generating those sets are generally not published (with an exception being Emanuel 2006), presentations have suggested that each member (TC event) of a stochastic set does not impact other TC members. Such an approach has the benefit of relative simplicity as well as rapidity of production, as each TC member can be produced without concern about simultaneous TCs in the basin. Given most real-world TCs are separated by several days or more, and distances of 2000km or more, this approach is seemingly well-founded for the majority of TC climatology. Yet, there have been many examples of TC-TC Fujiwhara interaction across the globe. While the interaction is much more common in the western Pacific, it is not unheard of in the Atlantic - with Connie and Diane in 1955 as two examples of such interaction but largely away from land. Further, the northeast U.S. coast can be threatened through such TC-TC interactions. The historic 1893 New York City Hurricane took an unusual NNW track (and landfall location) possibly as a consequence of interaction with one if not two additional nearby TCs. Numerical model (WRF) simulations of this case revealed exceptional difficulty in track prediction, illustrating further the complexity of the interaction. Interaction is not necessarily limited to another TC. Occasionally, a TC will interact with an occluded cold-core cyclone, which can then take the TC on a highly unusual track. Such interactions by their nature occur most often early or late in the TC season. Examples of TC-nonTC interaction include the 1938 New England Hurricane, Hurricane Hazel from 1950, and most recently, Hurricane Sandy, all of which had historic impacts in the region. Thus, the question raised here is: Is it necessary to account for the above cyclone interactions to accurately quantify TC risk for subregions of the U.S. coastline? This presentation will address this question by examining the distribution of TC motion vector across the basin, within subregions, and for the subset where TCs are within 1500km of each other (the threshold where interaction generally begins; Lander and Holland 1993) or less to determine if there is a systematic shift in motion (compared to single TC occurrences) that alters TC landfall threat regionally. Preliminary results show a statistically significant shift in TC motion when interaction is occurring -- a shift from bimodal motion (toward W or NE) to a unimodal motion (toward the N or NNW). This shift is not due to the Fujiwhara interaction itself (given the offsetting nature of the motion by one TC on the other), but instead is argued to be a consequence of enhanced Beta-drift resulting from the effective larger cyclonic circulation resulting from the two circulations interacting. The hypothesis is tested by reexamining shallow water model simulations of multiple TCs from prior work (Hart and Evans 1999). Potential implications of these results on the risk of midlatitude landfalls will be discussed.

Hart, R. E.

2013-12-01

149

5/29/09 6:33 PMGlobal Warming and Cyclones: a Vicious Cycle? : Discovery News Page 1 of 3http://dsc.discovery.com/news/2009/05/14/tropical-cyclones-warming-print.html  

E-print Network

://dsc.discovery.com/news/2009/05/14/tropical-cyclones-warming-print.html Discovery Channel « back Global Warming and Tropical Cyclones: a Vicious Cycle? Emily Sohn, Discovery News May 14, 2009 -- Global warming can change storm patterns. In turn, storms might help fuel global warming. A new study suggests that tropical cyclones shoot

Romps, David M.

150

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

NASA Astrophysics Data System (ADS)

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 of tropical cyclone precipitation relative to overall extreme precipitation from all weather systems combined. We used a surface observation network over the period 1972-2007, consisting of first-order and Cooperative Observer Program weather stations. Furthermore, to account for precipitation that may be unmeasured by rain gauges because of windy conditions during tropical cyclones, we employed a wind-corrected data set and the North American Regional Reanalysis. According to several metrics of extreme precipitation, we found that extreme precipitation from tropical cyclones has been increasing over the past few decades. Additionally, the contribution of tropical cyclone precipitation to overall extreme precipitation has been significantly increasing by approximately 5%-10% per decade in the southeastern Atlantic coastal states. We attribute this rise in tropical cyclone contribution to an increase in both the storm wetness (precipitation per storm) and storm frequency over the period of record. There is little evidence that changes in storm duration are responsible for the increase. As such, we believe that an important factor in accurately projecting changes in extreme precipitation rests on whether tropical cyclone activity is driven more by natural decadal oscillations or by large-scale warming of the environment.

Knight, David B.; Davis, Robert E.

2009-12-01

151

The poleward migration of the location of tropical cyclone maximum intensity  

NASA Astrophysics Data System (ADS)

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 tropical cyclones and in the environment. Here we mitigate this difficulty by focusing on a metric that is comparatively insensitive to past data uncertainty, and identify a pronounced poleward migration in the average latitude at which tropical cyclones have achieved their lifetime-maximum intensity over the past 30 years. The poleward trends are evident in the global historical data in both the Northern and the Southern hemispheres, with rates of 53 and 62 kilometres per decade, respectively, and are statistically significant. When considered together, the trends in each hemisphere depict a global-average migration of tropical cyclone activity away from the tropics at a rate of about one degree of latitude per decade, which lies within the range of estimates of the observed expansion of the tropics over the same period. The global migration remains evident and statistically significant under a formal data homogenization procedure, and is unlikely to be a data artefact. The migration away from the tropics is apparently linked to marked changes in the mean meridional structure of environmental vertical wind shear and potential intensity, and can plausibly be linked to tropical expansion, which is thought to have anthropogenic contributions.

Kossin, James P.; Emanuel, Kerry A.; Vecchi, Gabriel A.

2014-05-01

152

Tropical Cyclone Atmospheric Forcing for Ocean Response Models: Approaches and Issues  

Microsoft Academic Search

The specification of tropical cyclone atmospheric forcing for ocean response models is described with emphasis on methods that are currently actively applied in basins rich in in- situ, airborne and remotely sensed meteorological data. We emphasize approaches and critical issues addressed in more detail in this workshop's special session on Tropical Meteorology. Five alternative wind fields developed for Gulf of

V. J. Cardone; A. T. Cox

153

SST and North American Tropical Cyclone Landfall: A Statistical Modeling Study  

Microsoft Academic Search

We employ a statistical model of North Atlantic tropical cyclone (TC) tracks to investigate the relationship between sea-surface temperature (SST) and North American TC landfall rates. The track model is conditioned on summer SST in the tropical North Atlantic being in either the 19 hottest or the 19 coldest years in the period 1950-2005. For each conditioning many synthetic TCs

Timothy M. Hall; Stephen Jewson

2008-01-01

154

Forecasting tropical cyclone recurvature with upper tropospheric winds  

NASA Technical Reports Server (NTRS)

Data from 17 tropical cyclones during the 1974 through 1979 hurricane seasons are used to investigate whether the high level winds far to the northwest, north and northeast of the hurricane center can be used to predict hurricane track recurvature. When the man 200-mb winds 1500 to 2000 km northwest and north of the storm center equal or exceed 20 m/s, 80 per cent of the storms recurved before traveling as much as 12 degrees of longitude farther west. The high winds were also used to predict change in direction of forward motion during the next 72 hours. The regression equations developed explain up to 41 per cent of the variance in future direction. In addition to the geostrophic winds used, winds were also obtained by tracking clouds with successive satellite imagery. The u-components of the satellite winds are highly correlated with the geostrophic winds at 200-mb and could probably be used instead of them when available. The v-components are less highly correlated.

Gentry, R. C.

1983-01-01

155

Impacts of tropical cyclones on hydrochemistry of a subtropical forest  

NASA Astrophysics Data System (ADS)

Tropical cyclones (typhoons/hurricanes) have major impacts on the biogeochemistry of forest ecosystems, but the stochastic nature and the long intervals between storms means that there are limited data on their effects. We characterised the impacts of 14 typhoons over six years on hydrochemistry of a subtropical forest plantation in Taiwan, a region experiencing frequent typhoons. Typhoons contributed 1/3 of the annual rainfall on average, but ranged from 4 to 55%. The stochastic nature of annual typhoon related precipitation poses a challenge with respect to managing the impacts of these extreme events. This challenge is exacerbated by the fact that typhoon-related rainfall is not significantly correlated with wind velocity, the current focus of weather forecasts. Thus, little advance warning is provided for the hydrological impacts of these storms. The typhoons we studied contributed approximately one third of the annual input and output of most nutrients (except nitrogen) during an average 9.5 day yr-1 period, resulting in nutrient input/output rates an order of magnitude greater than during non-typhoon months. Nitrate output balanced input during the non-typhoon period, but during the typhoon period an average of 10 kg ha-1 yr-1 nitrate was lost. Streamwater chemistry exhibited similarly high variability during typhoon and non-typhoon periods and returned to pre-typhoon levels one to three weeks following each typhoon. The streamwater chemistry appears to be very resilient in response to typhoons, resulting in minimal loss of nutrients.

Chang, C. T.; Hamburg, S. P.; Hwong, J. L.; Lin, N. H.; Hsueh, M. L.; Chen, M. C.; Lin, T. C.

2013-10-01

156

Coupled atmosphere-wave-ocean modeling under tropical cyclone conditions  

NASA Astrophysics Data System (ADS)

A coupled atmosphere-wave-ocean modeling framework has been developed that is based on a comprehensive, physics-based treatment of the wind-wave-current interaction. In this framework, the surface boundary condition of the atmospheric model incorporates the sea-state dependent air-sea momentum flux. The wave model is forced by the sea-state dependent wind stress and includes the ocean surface current effect. The ocean model is forced by the sea-state dependent momentum flux and includes the ocean surface wave effects (Coriolis-Stokes effect, wave growth/decay effect, Langmuir turbulence effect). In this presentation we will focus on the sensitivity of the sea state dependence of the momentum flux to different theories. Major differences among these theories stem from the parameterization of wave form drag (or wave growth rate), the assumption of the mean wind profile, and the parameterization of the spectral tail. In addition, we will discuss the surface wave effect on the ocean model forcing. It is shown that the effective wind forcing (momentum flux) on ocean currents may be significantly different from the wind stress under tropical cyclone conditions, where the surface wave field is typically less developed and more complex. In addition, the upper ocean mixing may be significantly modified by the Stokes drift (Langmuir turbulence) depending on the surface wave conditions.

Ginis, I.; Hara, T.; Reichl, B.; Hughes, C.

2012-12-01

157

Dynamics of the Stratiform Sector of a Tropical Cyclone Rainband  

NASA Astrophysics Data System (ADS)

Airborne Doppler radar collected observations of the stationary rainband complex of Hurricane Rita (2005) in exceptional detail. Dynamics of the stationary rainband complex play a large role in the evolution of the tropical cyclone's internal structure. The stratiform sector of the stationary rainband complex occurs on the downwind end of the complex. This stratiform rainband is a mesoscale feature consisting of nearly uniform precipitation and weak vertical velocities from collapsing convective cells. Upward transport and associated latent heating occur within the stratiform cloud layer in the form of rising radial outflow. Below the cloud layer, descending radial inflow was driven by horizontal buoyancy gradients, and thus horizontal vorticity generation, introduced by regions of sublimational and melting cooling. The organization of this transport initially is robust but fades downwind as the convection dissipates. This descending inflow advected higher angular momentum inward, which resulted in the development of a midlevel tangential jet and broadening of the tangential wind field. This circulation may have also contributed to ventilation of the eyewall as inflow of low-entropy air continued past the rainband in both the boundary layer and midlevels. Given the expanse of the stratiform rainband region, its thermodynamic and kinematic impacts likely help to modify the structure and intensity of the overall storm.

Didlake, A. C.; Houze, R.

2013-12-01

158

Tropical cyclones in enhanced resolution CMIP5 experiments  

NASA Astrophysics Data System (ADS)

This study investigates the possible effects of global warming on tropical cyclone (TC) activity. The study is conducted using the coupled ocean-atmosphere global climate model EC-Earth configured at a relatively high resolution (T159 with 62 vertical levels), which is integrated following the CMIP5 protocol. By considering the late twentieth century (1979-2009) in the historical simulation and the twenty-first century end (2070-2100) in the RCP4.5 and RCP8.5 scenarios, significant future annual mean frequency decreases are found globally and in both hemispheres, accompanied by significant mean lifetime decreases and significant intensity increases, the latter being found through several different measures (but with caveats). In addition, the relatively novel aspect of simulating TCs of the past (1900-1930) is studied to further assess the robustness of the climate change results. These results suggest that TCs in the early twentieth century were more frequent in the southern hemisphere and dissipated more energy in the southern hemisphere and the South Indian Ocean. Although some model biases are present and the coarse model resolution prevents intense TCs in being simulated, reasonable TC simulation skill for other metrics (e.g., TC genesis, frequency of occurrence) is found when validated against present day observations. Thus the model displays an acceptable ability to connect TC climatology with the larger scale circulation.

Rathmann, Nicholas Mossor; Yang, Shuting; Kaas, Eigil

2014-02-01

159

Axisymmetrically Tropical Cyclone-like Vortices with Secondary Circulations  

E-print Network

The secondary circulation of the tropical cyclone (TC) is related to its formation and intensification, thus becomes very important in the studies. The analytical solutions have both the primary and secondary circulation in a three-dimensionally nonhydrostatic and adiabatic model. We prove that there are three intrinsic radiuses for the axisymmetrically ideal incompressible flow. The first one is the radius of maximum primary circular velocity $r_m$. The second one is radius of the primary kernel $r_k>r_m$, across which the vorticity of the primary circulation changes sign and the vertical velocity changes direction. The last one is the radius of the maximum primary vorticity $r_d$, at which the vertical flow of the secondary circulation approaches its maximum, and across which the radius velocity changes sign. The first TC-like vortex solution has universal inflow or outflow. The relations between the intrinsic length scales are $r_k=\\sqrt{2}r_m$ and $r_d=2r_m$. The second one is a multi-planar solution, per...

Sun, Liang

2013-01-01

160

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

161

Tropical cyclone track and genesis forecasting using satellite microwave sounder data  

NASA Technical Reports Server (NTRS)

Although many dynamical and statistical prediction schemes are available to forecasters, tropical cyclone track errors are still large. One primary difficulty is that tropical cyclones exist over the data-sparse tropical oceans. Satellite sounders, however, routinely provide numerous data over these areas. Mean layer temperatures from the Scanning Microwave Spectrometer on board the Nimbus 6 satellite are decomposed using empirical orthogonal functions, and the expansion coefficients are related to deviations from the persistence forecast location, to speed change, to direction change and to intensity change. The significance of the regression equations is tested by a null hypothesis of zero correlation coefficient. It appears that significant information about tropical cyclone motion exists in the satellite-estimated mean layer temperatures, especially at upper levels. A physical interpretation of the statistical results is offered, and a one-storm-out independent test is used to test the stability of the equations. Finally, some further work is suggested.

Kidder, S. Q.

1982-01-01

162

Assimilation of hyperspectral satellite radiance observations within tropical cyclones  

NASA Astrophysics Data System (ADS)

The availability of high resolution temperature and water vapor data is critical for the study of mesoscale scale weather phenomena (e.g., convective initiations, and tropical cyclones). As hyperspectral infrared sounders, the Atmospheric Infrared Sounder (AIRS) and Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) could provide high resolution atmospheric profiles by measuring radiations in many thousands of different channels. This work focuses on the assessment of the potential values of satellite hyperspectral radiance data on the study of convective initiations (CI) and the assimilation of AIRS radiance observations within tropical storms. First, the potential capability of hyperspectral infrared measurements (GIFTS) to provide convective precipitation forecasts has been studied and assessed. Using both the observed and the model-predicted profiles as input to the GIFTS radiative transfer model (RTM), it is shown that the simulated GIFTS radiance could capture the high vertical and temporal variability of the real and modeled atmosphere prior to a convective initiation, as well as the differences between observations and model forecasts. This study suggests the potential for hyperspectral infrared radiance data to make an important contribution to the improvement of the forecast skill of convective precipitation. Second, as the first step toward applying AIRS data to tropical cyclone (TC) prediction, a set of dropsonde profiles during Hurricane Rita (2005) is used to simulate AIRS radiance data and to assess the ability of AIRS data in capturing the vertical variability within TCs through one-dimensional variational (1D-Var) twin experiments. The AIRS observation errors and background errors are first estimated. Five sets of 1D-Var twin experiments are then performed using different combinations of AIRS channels. Finally, results from these 1D-Var experiments are analyzed. Major findings are: (1) AIRS radiance data contain useful information about the vertical variability of the temperature and water vapor within hurricanes; (2) assimilation of AIRS radiances significantly reduced errors in background temperature in the lower troposphere and relative humidity in the upper troposphere; (3) the near-real time (NRT) channel set provided by NOAA/NESDIS seems sufficient for capturing the vertical variability of the atmosphere in the upper troposphere of TCs, but not in the lower troposphere; and (4) the channels with weighting functions peak within the layer between 500-700 hPa could provide useful information to the atmospheric state below 700 hPa. A channel selection method is proposed to capture most vertical variability of temperature and water vapor within TCs contained in AIRS data. Finally, AIRS radiance data within TCs have been assimilated in the 1D-Var experiments with comparisons of the retrieval temperature and water vapor profiles with co-located Global Positioning System (GPS) radio occultation (RO) soundings and dropsonde profiles. The comparisons of AIRS 1DVar retrieval profiles with GPS RO sounding show that AIRS data can greatly improve the analysis of temperature and water vapor profiles within TCs. The comparisons of retrieval profiles with dropsonde data during Hurricane Rita, however, showed some discrepancies partly due to the difference of these two measurements and the uncertainties of the AIRS errors.

Lin, Haidao

163

Application of the Marsupial Paradigm to Tropical Cyclone Formation from Northwestward-Propagating Disturbances  

NASA Technical Reports Server (NTRS)

A wave-tracking algorithm is developed for northwestward-propagating waves that, on occasion, play a role in tropical cyclogenesis over the western oceans. To obtain the Lagrangian flow structure, the frame of reference is translated obliquely at the same propagation speed with the precursor disturbance. Trajectory analysis suggests that streamlines in the obliquely translated frame of reference can be used to approximate flow trajectories. The algorithm was applied to Super Typhoon Nakri (2008), Tropical Cyclone Erika (2009), and a few other examples. Diagnoses of meteorological analyses and satellite-derived moisture and precipitation fields show that the marsupial framework for tropical cyclogenesis in tropical easterly waves is relevant also for northwestward-propagating disturbances as are commonly observed in the tropical western Atlantic, the Gulf of Mexico, and the western North Pacific. Finally, it is suggested that analysis of the global model data and satellite observations in the marsupial framework can provide useful guidance on early tropical cyclone advisories.

Wang, Zhuo; Dunkerton, Timothy J.; Montgomery, Michael T.

2012-01-01

164

The Structural Changes of Tropical Cyclones Upon Interaction with Vertical Wind Shear  

NASA Technical Reports Server (NTRS)

The Fourth Convection and Moisture Experiment (CAMEX-4) provided a unique opportunity to observe the distributions and document the roles of important atmospheric factors that impact the development of the core asymmetries and core structural changes of tropical cyclones embedded in vertical wind shear. The state-of-the-art instruments flown on the NASA DC-8 and ER-2, in addition to those on the NOAA aircraft, provided a unique set of observations that documented the core structure throughout the depth of the tropical cyclone. These data have been used to conduct a combined observational and modeling study using a state-of-the-art, high- resolution mesoscale model to examine the role of the environmental vertical wind shear in producing tropical cyclone core asymmetries, and the effects on the structure and intensity of tropical cyclones.The scientific objectives of this study were to obtain in situ measurements that would allow documentation of the physical mechanisms that influence the development of the asymmetric convection and its effect on the core structure of the tropical cyclone.

Ritchie, Elizabeth A.

2003-01-01

165

Comparison of explicitly simulated and downscaled tropical cyclone activity in a high-resolution global climate model  

E-print Network

The response of tropical cyclone activity to climate change is a matter of great inherent interest and practical importance. Most current global climate models are not, however, capable of adequately resolving tropical ...

Emanuel, Kerry Andrew

166

Interannual variability of tropical cyclone activity in the southern South China Sea  

NASA Astrophysics Data System (ADS)

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 1996-2001 period. This study demonstrated that November and December were the most active months for tropical cyclone activity in this region. A majority of these storms attained tropical storm intensity. Also, a majority of the tropical cyclones originated within the study area near Malaysia as opposed to moving into the area. The long-term trend showed that there has been a slight increase in tropical cyclone activity in the region, but the trend was not statistically significant. A study of the interannual variability revealed that there was more (less) tropical cyclone activity in the region during La Niña (El Niño) years. Longer-term variability, such as that related to the Pacific Decadal Oscillation, was not found in the analysis here. Using spectral methods confirms that there was significant El Niño-related variability in climatological quantities such as monthly sea surface temperatures or pressures. Finally, the background climatological state was examined in order to determine whether or not the atmosphere in the region was more conducive to tropical cyclone formation or maintenance during active years. It was found that the most active years were associated with warmer SSTs in the study region, relatively weak 200-850 hPa wind shear, a warm-core structure, more water vapor, and more cyclonic low-level relative vorticity, and these were all La Niña-type years. Nonactive years were associated with weaker wind shear, less water vapor, and a more anticyclonic (vorticity) background, regardless of whether the SSTs were warmer or cooler, and most of these were El Niño-type years.

Zuki, Zabani M.; Lupo, Anthony R.

2008-03-01

167

The Impact of the Saharan Air Layer on Tropical Cyclones and Tropical Climate  

NASA Astrophysics Data System (ADS)

Infrared and microwave satellite imagery has steadily improved our ability to detect low to mid-level dry air at tropical latitudes and in the environments of tropical disturbances. However, understanding how this dry air affects the tropical atmosphere and tropical systems remains a difficult challenge. This presentation will discuss the impacts of intraseasonal low to mid-level dry air sources (e.g. the Saharan Air Layer and mid-latitude dry air intrusions) on the mean atmospheric state of the tropical North Atlantic and present new mean soundings for this region of the world. Discussion will also include recent research that is examining how the tropical cyclone diurnal cycle and associated diurnal pulses might provide a means for helping environmental dry air influence the storm environment. Special infrared GOES imagery reveals that the timing of these diurnal pulses in the TC environment are remarkably predictable in both time and space and suggests that these features steadily propagate away from the storm each day. As these diurnal pulses reach peripheral TC radii where low to mid-level dry air is place, substantial arc clouds (100s of km in length and lasting for several hours) have been observed forming along the leading edge of the pulse. It is hypothesized that the processes leading to the formation of arc cloud events can significantly impact an AEW or TC (particularly smaller, less developed systems). Specifically, the cool, dry air associated with the convectively-driven downdrafts that form arc clouds can help stabilize the middle to lower troposphere and may even act to stabilize the boundary layer. The arc clouds themselves may also act to disrupt the storm. As they race away from the convective core region, they create low-level outflow in the quadrant/semicircle of the AEW or TC in which they form. This outflow pattern counters the typical low-level inflow that is vital for TC formation and maintenance.

Dunion, J.

2012-12-01

168

Understanding the impact of saharan dust aerosols on tropical cyclones  

NASA Astrophysics Data System (ADS)

Genesis of Tropical Cyclones (TCs) in the main development region for Atlantic hurricanes is tied to convection initiated by African easterly waves (AEWs) during Northern hemisphere summer and fall seasons. The main development region is also impacted by dust aerosols transported from the Sahara. It has been hypothesized that dust aerosols can modulate the development of TCs through aerosol-radiation and aerosol-cloud interaction processes. In this study, we investigate the impact of dust aerosols on TC development using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem). We first develop a technique to constrain the WRF-Chem model with a realistic three-dimensional spatial distribution of dust aerosols. The horizontal distribution of dust is specified using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived aerosol products and output from the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. The vertical distribution of dust is constrained using the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). We validate our technique through in situ aircraft measurements where both showed aerosol number concentrations from 20-30 cm-3 in the atmosphere for Saharan dust moving over the eastern Atlantic Ocean. Then, we use the satellite data constraint technique to nudge the WRF-Chem aerosol fields throughout the simulation of TC Florence developing over the eastern Atlantic Ocean during September 2006. Three different experiments are conducted where the aerosol-radiation and aerosol-cloud interaction processes are either activated or deactivated in the model while all other model options are identical between the experiments. By comparing the model experiment results, the impact of the aerosol interaction processes on TC development can be understood. The results indicate that dust aerosols can delay or prevent the development of a TC as the minimum sea level pressure of TC Florence was 13 hPa higher when the aerosols interactions were activated as opposed to deactivated in the model.

Naeger, Aaron

169

Have Tropical Cyclones Been Feeding More Extreme Rainfall?  

NASA Technical Reports Server (NTRS)

We have conducted a study of the relationship between tropical cyclone (TC) and extreme rain events using GPCP and TRMM rainfall data, and storm track data for July through November (JASON) in the North Atlantic (NAT) and the western North Pacific (WNP). Extreme rain events are defined in terms of percentile rainrate, and TC-rain by rainfall associated with a named TC. Results show that climatologically, 8% of rain events and 17% of the total rain amount in NAT are accounted by TCs, compared to 9% of rain events and 21% of rain amount in WNP. The fractional contribution of accumulated TC-rain to total rain, Omega, increases nearly linearly as a function of rainrate. Extending the analyses using GPCP pentad data for 1979-2005, and for the post-SSM/I period (1988-2005), we find that while there is no significant trend in the total JASON rainfall over NAT or WNP, there is a positive significant trend in heavy rain over both basins for the 1979-2005 period, but not for the post-SSM/I period. Trend analyses of Omega for both periods indicate that TCs have been feeding increasingly more to rainfall extremes in NAT, where the expansion of the warm pool area can explain slight more than 50% of the change in observed trend in total TC rainfall. In WNP, trend signals for Omega are mixed, and the long-term relationship between TC rain and warm pool areas are strongly influenced by interannual and interdecadal variability.

Lau, K.-M.; Zhou, Y. P.; Wu, H.-T.

2008-01-01

170

Have Tropical Cyclones been Feeding More Extreme Rainfall?  

NASA Technical Reports Server (NTRS)

We have conducted a study of the relationship between tropical cyclone (TC) and extreme rain events using GPCP and TRMM rainfall data ; and storm track data for July through November (JASON) in the North Atlantic (NAT) and the western North Pacific (WNP). Extreme rain events are defined in terms of percentile rainrate, and TC-gain by rainfall associated with a named TC. Results show that climatologically, 8% of rain events and 17% of the total rain amount in NAT are accounted by TCs, compared to 9% of rain events, and 21% of rain amount in WN.P. The fractional contribution of accumulated TC-rain to total rain, Omega, increases nearly linearly as a function of rainrate. Extending the analyses using GPCP pentad data for 1979-2005, and for the post-SSM/I period (1988-2005), we find that while there is no significant trend in the total JASON rainfall over NAT or WNP there is a positive significant trend in heavy rain over both basins for the 1979-2005 period, but not for the post-SSM/I period. Trend analyses of Omega for bout periods indicate that TCs have been feeding increasingly more to rainfall extremes in NAT, where the expansion of the warm pool area can explain slightly more than 50% of the change in observed trend in total TC rainfall. In. WNP, trend signals for Omega are mixed, and the loner term relationship between TC rain and warm pool area is strongly influenced by interannual and interdecadal variability.

Lau, K.-M.; Zhou, Y. P.; Wu, H.-T.

2008-01-01

171

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

172

Impacts of El Niño Southern Oscillation Events on Tropical Cyclone Landfalling Activity in the Western North Pacific  

Microsoft Academic Search

The impact of El Niño Southern Oscillation (ENSO) episodes on the variability in the landfalling pattern of tropical cyclones in the western North Pacific is studied using the bootstrap technique.It is found that, relative to neutral years, in the months September, October, and November or the late season of El Niño years the number of tropical cyclones landfalling in the

M. C. Wu; W. L. Chang; W. M. Leung

2004-01-01

173

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

174

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

175

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

NASA Astrophysics Data System (ADS)

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.

Truchelut, R.; Hart, R. E.

2013-12-01

176

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)

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.

Wilson, Robert M.

2014-01-01

177

Tropical cyclone induced physical and biogeochemical response in the Arabian Sea  

NASA Astrophysics Data System (ADS)

Tropical cyclone moving over a warm ocean is a manifestation of intense air-sea interaction process. Though the destructive power associated with the landfall of a cyclone is well known, its role in enhancing the biological production, and associated biogeochemical fluxes is least understood. In the Arabian Sea, located in the western part of the north Indian Ocean, tropical cyclones occurs regularly during spring (April-May) and fall (October-November) intermonsoons. In this presentation the life cycle of a tropical cyclone Phyan, which occurred during 9-11 November 2009 in the Arabian Sea is analyzed to understand the quantitative response in sea surface temperature (SST), chlorophyll concentration, net primary production (NPP) and CO2 out-gassing using a variety of remotely sensed as well as in situ data. Associated with the passage of cyclone, SST showed a rapid cooling of 2oC. The cooling was in response to the strong cyclonic wind stress curl and associated upward Ekman-pumping. The chlorophyll biomass as well as net primary productivity showed a 2-fold increase. The biological response mediated by the upward Ekman pumping-driven vertical transport of subsurface nutrient showed a time lag of 3-4 days. During the period of cyclone development, entrainment of CO2 into the surface ocean by turbulent mixing and Ekman-pumping enhanced the out-gassing from the ocean, which was 0.123 Tg C. This accounted for ~85% of the total out-gassing from the eastern Arabian Sea during November. Thus, if the frequency and intensity of the cyclone increases in future due to warming, the Arabian Sea would become more productive, and also release more CO2 to the atmosphere than the present. In addition, increased productivity, in turn, will exert increased demand on mid-depth oxygen exerting additional stress on already existing oxygen minimum zone (OMZ).

Kumar, Prasanna; Bhaskar, Byju

2013-04-01

178

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

PubMed

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

Grimbacher, Peter S; Stork, Nigel E

2009-09-01

179

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

180

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

NASA Astrophysics Data System (ADS)

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.

Hsiang, S. M.

2009-12-01

181

Can existing climate models be used to study anthropogenic changes in tropical cyclone climate?  

NASA Astrophysics Data System (ADS)

The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While the model resolution is insufficient to reproduce the fine structure of tropical cyclones, the simulated storms become more realistic as resolution is increased. To obtain a preliminary estimate of the response of the tropical cyclone climatology, CO2 was doubled using models with varying cloud treatments and different horizontal resolutions. In the experiment with prescribed cloudiness, the number of storm-days, a combined measure of the number and duration of tropical storms, undergoes a statistically significant increase in the doubled-CO2 climate. In contrast, a smaller but significant reduction of the number of storm-days is indicated in the experiment with cloud feedback. In both cases the response is independent of horizontal resolution. While the inconclusive nature of these experimeital results highlights the uncertainties that remain in examining the details of greenhouse gas induced climate change, the ability of the models to qualitatively simulate the tropical storm climatology suggests that they are appropriate tools for this problem.

Broccoli, A. J.; Manabe, S.

1990-10-01

182

Can existing climate models be used to study anthropogenic changes in tropical cyclone climate  

SciTech Connect

The utility of current generation climate models for studying the influence of greenhouse warming on the tropical storm climatology is examined. A method developed to identify tropical cyclones is applied to a series of model integrations. The global distribution of tropical storms is simulated by these models in a generally realistic manner. While the model resolution is insufficient to reproduce the fine structure of tropical cyclones, the simulated storms become more realistic as resolution is increased. To obtain a preliminary estimate of the response of the tropical cyclone climatology, CO{sub 2} was doubled using models with varying cloud treatments and different horizontal resolutions. In the experiment with prescribed cloudiness, the number of storm-days, a combined measure of the number and duration of tropical storms, undergoes a statistically significant reduction of the number of storm-days is indicated in the experiment with cloud feedback. In both cases the response is independent of horizontal resolution. While the inconclusive nature of these experimental results highlights the uncertainties that remain in examining the details of greenhouse-gas induced climate change, the ability of the models to qualitatively simulate the tropical storm climatology suggests that they are appropriate tools for this problem.

Broccoli, A.J.; Manabe, S.

1990-10-01

183

Condensed water in tropical cyclone "Oliver", 8 February 1993  

NASA Astrophysics Data System (ADS)

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 the freezing level was reached near 17,000 feet (5.2 km) pressure altitude. The cloud was completely glaciated at -5°C. There was no correlation between ice particle habit and ambient temperature. In the liquid phase, the precipitation-cloud drop concentration was 4.0 × 10 3 m -3, the geometric mean diameter Dg=0.5-0.7 mm, and the liquid water content 0.7-1.9 g m -3. The largest particles anywhere in the cloud, dominated by fused dendrites at concentrations similar to that of raindrops (2.5 × 10 3 m -3) but a higher condensed water content (5.4 g m -3 estimated) were found in the mixed phase; condensed water is removed very effectively from the mixed layer due to high settling velocities of the large mixed particles. The highest number concentration (4.9 × 10 4 m -3), smallest size ( Dg=0.3-0.4 mm), largest surface area (up to 2.6 × 10 2 cm 2 m -3 at 0.4-1.0 g m -3 of condensate) existed in the ice phase at the coldest temperature (-40°C) at 35,000 feet (10.7 km). Each cloud contained aerosol (haze particles) in addition to cloud particles. The aerosol total surface area exceeded that of the cirrus particles at the coldest temperature. Thus, aerosols must play a significant role in the upscattering of solar radiation. Light extinction (6.2 km -1) and backscatter (0.8 sr -1 km -1) was highest in the coldest portion of the cirrus cloud at the highest altitude.

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

184

Landfalling Tropical Cyclones: Forecast Problems and Associated Research Opportunities  

USGS Publications Warehouse

The Fifth Prospectus Development Team of the U.S. Weather Research Program was charged to identify and delineate emerging research opportunities relevant to the prediction of local weather, flooding, and coastal ocean currents associated with landfalling U.S. hurricanes specifically, and tropical cyclones in general. Central to this theme are basic and applied research topics, including rapid intensity change, initialization of and parameterization in dynamical models, coupling of atmospheric and oceanic models, quantitative use of satellite information, and mobile observing strategies to acquire observations to evaluate and validate predictive models. To improve the necessary understanding of physical processes and provide the initial conditions for realistic predictions, a focused, comprehensive mobile observing system in a translating storm-coordinate system is required. Given the development of proven instrumentation and improvement of existing systems, three-dimensional atmospheric and oceanic datasets need to be acquired whenever major hurricanes threaten the United States. The spatial context of these focused three-dimensional datasets over the storm scales is provided by satellites, aircraft, expendable probes released from aircraft, and coastal (both fixed and mobile), moored, and drifting surface platforms. To take full advantage of these new observations, techniques need to be developed to objectively analyze these observations, and initialize models aimed at improving prediction of hurricane track and intensity from global-scale to mesoscale dynamical models. Multinested models allow prediction of all scales from the global, which determine long- term hurricane motion to the convective scale, which affect intensity. Development of an integrated analysis and model forecast system optimizing the use of three-dimensional observations and providing the necessary forecast skill on all relevant spatial scales is required. Detailed diagnostic analyses of these datasets will lead to improved understanding of the physical processes of hurricane motion, intensity change, the atmospheric and oceanic boundary layers, and the air- sea coupling mechanisms. The ultimate aim of this effort is the construction of real-time analyses of storm surge, winds, and rain, prior to and during landfall, to improve warnings and provide local officials with the comprehensive information required for recovery efforts in the hardest hit areas as quickly as possible.

Marks, F.D.; Shay, L.K.; Barnes, G.; Black, P.; Demaria, M.; McCaul, B.; Mounari, J.; Montgomery, M.; Powell, M.; Smith, J.D.; Tuleya, B.; Tripoli, G.; Xie, L.; Zehr, R.

1998-01-01

185

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

PubMed Central

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

Mei, Wei; Primeau, Francois; McWilliams, James C.; Pasquero, Claudia

2013-01-01

186

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

NASA Astrophysics Data System (ADS)

On 2 May 2008, category-4 tropical cyclone Nargis devastated Myanmar. It was observed that just prior to its landfall, Nargis rapidly intensified from a weak category-1 storm to an intense category-4 storm within only 24 h. 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. In the anomaly, the subsurface ocean is evidently warmer than climatology, as characterized by the depth of the 26°C isotherm of 73-101 m and the tropical cyclone heat potential of 77-105 kj cm-2. This pre-existing deep, warm subsurface layer leads to reduction in the cyclone-induced ocean cooling, as shown from the ocean mixed layer numerical experiments. As a result, there was a near 300% increase in the air-sea enthalpy flux to support Nargis' rapid intensification.

Lin, I.-I.; Chen, Chi-Hong; Pun, Iam-Fei; Liu, W. Timothy; Wu, Chun-Chieh

2009-02-01

187

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

NASA Technical Reports Server (NTRS)

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).

Tripoli, G. J.

1992-01-01

188

On the ability of global Ensemble Prediction Systems to predict tropical cyclone track probabilities  

E-print Network

probabilities Sharanya J. Majumdar and Peter M. Finocchio University of Miami, Miami, Florida Submitted The ability of ensemble prediction systems to predict the probability that a tropical cyclone will fall within to be more accurate than all models except its deterministic counterpart. Dynamic probability circles

Majumdar, Sharan

189

Quantifying the Shapes of U.S. Landfalling Tropical Cyclone Rain Shields  

Microsoft Academic Search

Tropical cyclones (TCs) produce complex rainfall patterns that are difficult to predict due to atmospheric and land surface forcings. This study utilizes geographic information systems to spatially analyze radar returns and calculate several metrics that quantify the shapes of TC rain shields. Three stepwise discriminant analyses are performed to determine which of the shape metrics distinguish among TCs categorized by:

Corene Matyas

2007-01-01

190

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

E-print Network

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

Texas at Austin. University of

191

The effect of ice-phase microphysics on tropical cyclones simulated by the Lokalmodell  

Microsoft Academic Search

It is known that the release of latent heat is essential for the growth and the longe- vity of tropical cyclones. Furthermore, it is necessary for the maintenance of storms that the formed condensate must be removed from the vortex area before it may be evaporated in subsaturated air. Therefore, the formation of precipitation and fallout are important processes in

Thomas Frisius; Thomas Hasselbeck; Fritz Herbert; Theoretische Meteorologie

192

Atlantic Warm Pool acting as a link between Atlantic Multidecadal Oscillation and Atlantic tropical cyclone activity  

Microsoft Academic Search

Multidecadal variability of Atlantic tropical cyclone activity is observed to relate to the Atlantic Multidecadal Oscillation (AMO), a mode manifesting primarily in sea surface temperature (SST) in the high latitudes of the North Atlantic. In the low latitudes of the North Atlantic, a large body of warm water called the Atlantic Warm Pool (AWP) comprises the Gulf of Mexico, the

Chunzai Wang; Sang-Ki Lee; David B. Enfield

2008-01-01

193

Dendrotempestology and the Isotopic Record of Tropical Cyclones in Tree Rings  

E-print Network

the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO)) combined with other observed for the Atlantic Ocean (Klotzbach 2006), perhaps due to increasing SSTs. Energy dissipation 2005 tropical cyclone season in the Atlantic Ocean was likely caused by abnormally high SSTs (0.9"C

Grissino-Mayer, Henri D.

194

Revisiting the Influence of the Quasi-Biennial Oscillation on Tropical Cyclone Activity  

E-print Network

al. 2010), the Atlantic multidecadal oscillation (AMO; Goldenberg et al. 2001; Zhang and DelworthRevisiting the Influence of the Quasi-Biennial Oscillation on Tropical Cyclone Activity SUZANA J form 7 June 2010) ABSTRACT The statistical relationship between the quasi-biennial oscillation (QBO

Sobel, Adam

195

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

Microsoft Academic Search

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

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

1997-01-01

196

Sea Surface Temperature and the Maximum Intensity of Atlantic Tropical Cyclones  

Microsoft Academic Search

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

Mark Demaria; John Kaplan

1994-01-01

197

Influence of tropical cyclones on seasonal ocean circulation in the South China Sea  

Microsoft Academic Search

The seasonal variability of South China Sea (SCS) ocean circulation influenced by tropical cyclones (TCs) is studied by using satellite QuikSCAT wind data, Sverdrup theory, and a reduced gravity model. TCs can induce a positive (negative) wind stress curl in the northwestern (southeastern) SCS in summer and a positive wind stress curl for the whole SCS in winter. With these

Guihua Wang; Zheng Ling; Chunzai Wang

2009-01-01

198

Variability in tornado frequency associated with U.S. landfalling tropical cyclones  

Microsoft Academic Search

A statistical model for tornado frequency from Gulf of Mexico landfalling tropical cyclones (TCs) is developed using TC size, intensity, recurvature, and mid-level specific humidity data. New datasets are assembled for tornado frequency and for TC size at landfall as measured by the radius of outer closed isobar and distance of tornado from the TC center. Owing to systematic undercounting

James I. Belanger; Judith A. Curry; Carlos D. Hoyos

2009-01-01

199

Response of tropical cyclone potential intensity over the north Indian Ocean to global warming  

Microsoft Academic Search

The responses of tropical cyclone (TC) potential intensity (PI) and the associated environmental control parameters over the North Indian Ocean (NIO) to the doubled CO2 concentration are assessed based on the ensemble simulation from 15 coupled general circulation models (CGCMs) participated in the Intergovernmental Panel for Climate Change (IPCC) Forth Assessment Report (AR4). The results show that the annual mean

Jinhua Yu; Yuqing Wang

2009-01-01

200

The Influence of Airborne Doppler Radar Data Quality on Numerical Simulations of a Tropical Cyclone  

E-print Network

The Influence of Airborne Doppler Radar Data Quality on Numerical Simulations of a Tropical Cyclone LEI ZHANG* AND ZHAOXIA PU Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah- clones (TCs) has been well recognized. However, the influence of radar data quality on the numerical

Pu, Zhaoxia

201

Extreme wind conditions in tropical cyclones observed from synthetic aperture radar images  

Microsoft Academic Search

Both atmospheric and oceanic processes play an important role in the dynamics of tropical cyclones. Due to the relatively small amount of in situ data available for extreme events like hurricanes or typhoons remote sensing techniques play an important role in the measurement of the relevant geophysical parameters. In this paper some recent results on SAR observation of extreme wind

A. Reppucci; S. Lehner; J. Schulz-Stellenfleth; H. Breit

2007-01-01

202

Effects of Environmental Water Vapor on Tropical Cyclone Structure and Intensity  

Microsoft Academic Search

The tropical cyclone (TC) and environmental interaction is not fully understood. Previous studies have demonstrated that this interaction affects intensity change. The studies found that intensification is favored in low shear, moist environments, with high sea surface temperatures (SST). However, little precise quantification was provided, especially in terms of the impact of environmental water vapor on TC intensity change. This

Derek Ortt

2007-01-01

203

Tropical cyclones and the ecohydrology of Australia's recent continental-scale drought  

E-print Network

Tropical cyclones and the ecohydrology of Australia's recent continental-scale drought Gavan S. Mc. [1] The Big Dry, a recent drought over southeast Australia, began around 1997 and continued until 2011. We show that between 2002­2010, instead of a localized drought, there was a continent

Tregoning, Paul

204

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

E-print Network

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

Grissino-Mayer, Henri D.

205

Evolution of the Surface Wind Field in an Intensifying Tropical Cyclone  

Microsoft Academic Search

The surface wind field in a developing tropical cyclone (Agnes, 1972) was analyzed over a 1660 km radius for four days using conventional surface data, as the storm evolved from a disorganized depression to a hurricane. The transition to hurricane intensity was characterized by a wavelike disturbance propagating inward at 15 m s1 from the outermost radii to the storm

John Molinari; Steven Skubis

1985-01-01

206

Service Assessment. Hurricane/Post-Tropical Cyclone Sandy, October 22-29, 2012.  

National Technical Information Service (NTIS)

On October 22-29, 2012, Hurricane/Post-Tropical Cyclone Sandy moved from the Caribbean to the U.S. Eastern Seaboard, ultimately making landfall near Brigantine, NJ, around 7:30 p.m. on October 29. The storm resulted in an enormous impact to life and prope...

2013-01-01

207

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

PubMed

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

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

2014-01-30

208

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

NASA Astrophysics Data System (ADS)

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. However, in transient simulations featuring historical and projected anthropogenic climate forcing, the addition of tropical cyclone mixing decreases model ocean heat content, which reduces a positive model bias compared to climatological anomalous upper ocean heat content during the period 1950-2000. This decrease is primarily caused by changes in the spatial structure of surface ocean heat fluxes that reflect cooler tropical temperatures due to enhanced mixing in storm regions and warmer high-latitude temperatures associated with increased poleward heat transport in the mid-latitudes. Furthermore, tropical cyclone mixing regulates the strength of the meridional overturning circulation, mitigating a projected slowdown in the model during the next 100 years. These results support the hypothesis that tropical cyclone-induced ocean mixing may actively contribute to the dynamics of the climate system, particularly as a tropical thermostat within climate-change scenarios.

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

2009-12-01

209

The impact of verification area design on tropical cyclone targeted observations based on the CNOP method  

NASA Astrophysics Data System (ADS)

This study investigated the impact of different verification-area designs on the sensitive areas identified using the conditional nonlinear optimal perturbation (CNOP) method for tropical cyclone targeted observations. The sensitive areas identified using the first singular vector (FSV) method, which is the linear approximation of CNOP, were also investigated for comparison. By analyzing the validity of the sensitive areas, the proper design of a verification area was developed. Tropical cyclone Rananim, which occurred in August 2004 in the northwest Pacific Ocean, was studied. Two sets of verification areas were designed; one changed position, and the other changed both size and position. The CNOP and its identified sensitive areas were found to be less sensitive to small variations of the verification areas than those of the FSV and its sensitive areas. With larger variations of the verification area, the CNOP and the FSV as well as their identified sensitive areas changed substantially. In terms of reducing forecast errors in the verification area, the CNOP-identified sensitive areas were more beneficial than those identified using FSV. The design of the verification area is important for cyclone prediction. The verification area should be designed with a proper size according to the possible locations of the cyclone obtained from the ensemble forecast results. In addition, the development trend of the cyclone analyzed from its dynamic mechanisms was another reference. When the general position of the verification area was determined, a small variation in size or position had little influence on the results of CNOP.

Zhou, Feifan; Mu, Mu

2011-09-01

210

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

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

211

On the interaction of Tropical Cyclone Flossie and emissions from Hawaii's Kilauea volcano  

NASA Astrophysics Data System (ADS)

29 July 2013, Tropical Storm Flossie passed the Hawaiian Islands. This is the first interaction between an active, vigorously degassing volcano and a tropical cyclone captured by a vog (volcanic smog) dispersion model run over the Hawaiian Islands since operational simulations began in 2010, providing a unique opportunity to analyze the influence of robust volcanic emissions entrained into a tropical cyclone. Results from the vog dispersion model are compared with Geostationary Operational Environmental Satellite observations, lightning data from Vaisala's Global Lightning Dataset (GLD360), and the National Weather Service Weather Surveillance Radar, 1988 Dual-Polarmetric Doppler radar to investigate the effect of volcanic emissions on the storm. Observations and model results suggest that aerosol loading resulted in deep convection and glaciation which in turn enhanced charge separation and promoted active lightning.

Pattantyus, Andre; Businger, Steven

2014-06-01

212

Lightning activity within tropical cyclones in the South West Indian Ocean  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

213

Intense convection vs. widespread precipitation: Which is more important for tropical cyclone intensification?  

NASA Astrophysics Data System (ADS)

Ever since Malkus and Riehl introduced "hot towers" into the lexicon and stated their importance for tropical cyclone energetics, it has often been assumed that intense deep convection near the center of a tropical disturbance favors intensification. Certainly, case studies have shown intensification following "bursts" of deep convection. However, other studies have shown that intensification may be more closely related to the fractional coverage of precipitation near the cyclone center, suggesting that symmetrical latent heat release may be more important than the intensity of convection. First, we summarize recent uses of the 14-year database of TRMM Precipitation Features in tropical cyclones that have examined this issue globally. In addition, we also undertake a detailed compilation of passive microwave overpasses in 10 genesis situations, comparing measures of convective intensity (lowest Tb in the ice scattering channel) vs. measures of total rainfall in the inner core, in an attempt to learn the relative importance of symmetric vs. asymmetric convection prior to a system attaining tropical depression status.

Zipser, E. J.; Zawislak, J. A.; Liu, C.; Jiang, H.

2012-12-01

214

Operational Evaluation of QuikSCAT Winds in Tropical Cyclones at the Tropical Prediction Center/National Hurricane Center  

NASA Astrophysics Data System (ADS)

Remotely sensed ocean surface vector winds from the QuikSCAT scatterometer aboard the NASA SeaWinds satellite are an important source of data at the Tropical Prediction Center (TPC)/National Hurricane Center (NHC). These data fill a large void in surface wind information over the open ocean portion of the NHC/TPC area of responsibility in the Eastern Pacific and Atlantic basins. QuikSCAT has been used at TPC/NHC to supplement other observations for estimation of tropical cyclone (TC) intensity and the radius of 34-kt and 50- kt winds. Both of these parameters are critical to the warning and forecast mission at TPC. In the TC environment, the quality of QuikSCAT winds is often degraded by rain contamination. However, the interpretation of the impact of rain on QuikSCAT winds is not straightforward, since no direct measurement of rain rate is co-located with the instrument, and the impact of rain varies with the rain rate and the actual near- surface wind speed. Examination of QuikSCAT wind data within the range of coastal radar and other rain rate estimates such as those from the Tropical Rainfall Measurement Mission (TRMM) have shown a strong relationship between high wind estimates from the scatterometer and rain rate. To quantify the accuracy of QuikSCAT winds in estimating TC intensity, maximum wind speeds from 25-km and 12.5-km near-real time QuikSCAT retrievals over classified TCs during the 2005 and 2006 Atlantic hurricane seasons are compared to the NHC best track intensity and Dvorak satellite intensity estimates. Results from 2005 indicate a positive bias in QuikSCAT maximum winds for tropical depressions and weak tropical storms due to rain enhancing backscatter to the instrument. A large negative bias of QuikSCAT intensity estimates was seen for hurricanes with maximum winds above 85 kt due to rain attenuation, resolution limitations, and signal saturation at high winds speed. QuikSCAT intensity estimates showed more skill in moderate to strong tropical storms and marginal hurricanes; although some of this reduced bias results from the cancellation of larger errors of opposite sign in this range of wind speeds. Estimates of outer wind radii have proven very useful, especially in major hurricanes where the maximum radius of 34 kt winds often extends outside the region of heavy rainfall near the TC center. These bulk statistical results indicate that QuikSCAT winds in the TC environment can provide valuable information, but must be carefully evaluated on a case-by-case basis. Results from 2006 will be evaluated and compared to those from 2005. Also, case examples comparing QuikSCAT winds to measurements from aircraft reconnaissance, the NOAA stepped-frequency microwave radiometer (SFMR), and ship and buoy observations will be presented. These examples will highlight the difficulty of interpreting QuikSCAT winds in an operational setting. Additionally, an evaluation of a new near-real time QuikSCAT retrieval algorithm developed by NASA and NOAA NESDIS may be possible prior to the end of the 2006 hurricane season. Finally, suggestions will be made for improvements to future ocean vector wind platforms necessary to support the operational mission at TPC.

Sobolowski, S.; Frei, A.; Mahani, S.

2005-05-01

215

Operational Evaluation of QuikSCAT Winds in Tropical Cyclones at the Tropical Prediction Center/National Hurricane Center  

NASA Astrophysics Data System (ADS)

Remotely sensed ocean surface vector winds from the QuikSCAT scatterometer aboard the NASA SeaWinds satellite are an important source of data at the Tropical Prediction Center (TPC)/National Hurricane Center (NHC). These data fill a large void in surface wind information over the open ocean portion of the NHC/TPC area of responsibility in the Eastern Pacific and Atlantic basins. QuikSCAT has been used at TPC/NHC to supplement other observations for estimation of tropical cyclone (TC) intensity and the radius of 34-kt and 50- kt winds. Both of these parameters are critical to the warning and forecast mission at TPC. In the TC environment, the quality of QuikSCAT winds is often degraded by rain contamination. However, the interpretation of the impact of rain on QuikSCAT winds is not straightforward, since no direct measurement of rain rate is co-located with the instrument, and the impact of rain varies with the rain rate and the actual near- surface wind speed. Examination of QuikSCAT wind data within the range of coastal radar and other rain rate estimates such as those from the Tropical Rainfall Measurement Mission (TRMM) have shown a strong relationship between high wind estimates from the scatterometer and rain rate. To quantify the accuracy of QuikSCAT winds in estimating TC intensity, maximum wind speeds from 25-km and 12.5-km near-real time QuikSCAT retrievals over classified TCs during the 2005 and 2006 Atlantic hurricane seasons are compared to the NHC best track intensity and Dvorak satellite intensity estimates. Results from 2005 indicate a positive bias in QuikSCAT maximum winds for tropical depressions and weak tropical storms due to rain enhancing backscatter to the instrument. A large negative bias of QuikSCAT intensity estimates was seen for hurricanes with maximum winds above 85 kt due to rain attenuation, resolution limitations, and signal saturation at high winds speed. QuikSCAT intensity estimates showed more skill in moderate to strong tropical storms and marginal hurricanes; although some of this reduced bias results from the cancellation of larger errors of opposite sign in this range of wind speeds. Estimates of outer wind radii have proven very useful, especially in major hurricanes where the maximum radius of 34 kt winds often extends outside the region of heavy rainfall near the TC center. These bulk statistical results indicate that QuikSCAT winds in the TC environment can provide valuable information, but must be carefully evaluated on a case-by-case basis. Results from 2006 will be evaluated and compared to those from 2005. Also, case examples comparing QuikSCAT winds to measurements from aircraft reconnaissance, the NOAA stepped-frequency microwave radiometer (SFMR), and ship and buoy observations will be presented. These examples will highlight the difficulty of interpreting QuikSCAT winds in an operational setting. Additionally, an evaluation of a new near-real time QuikSCAT retrieval algorithm developed by NASA and NOAA NESDIS may be possible prior to the end of the 2006 hurricane season. Finally, suggestions will be made for improvements to future ocean vector wind platforms necessary to support the operational mission at TPC.

Brennan, M. J.; Knabb, R.

2006-12-01

216

A Quasi-tropical Cyclone Over The Western Mediterranean: Dynamical Vs Boundary Factors  

NASA Astrophysics Data System (ADS)

A small, quasi-tropical cyclone occurred on 11 and 12 September 1996 over the West- ern Mediterranean. Intense convective activity over the region during this period also produced a tornado outbreak in the Balearic Islands and torrential precipitation over eastern mainland Spain. Numerical experiments using the MM5 model are used to analyze this event. A sensitivity study, with a factors separation technique, examin- ing the upper-level dynamic forcing, latent heat flux from the sea, and orography is conducted. A potential vorticity (PV) inversion technique is used to reduce the ampli- tude of an upper-level intense trough and then evaluate its effects. Orography does not play a significant role during this particular cyclone development. Conversely, both the latent heat flux and the upper-level trough are crucial for low-level cyclogenesis, resulting in an air-sea interaction instability. At the first stage of the cyclogenesis, the upper-level PV anomaly enhanced the low-level circulation of the synoptic-scale low and enhanced the latent heat flux from the sea. During its mature stage, the circula- tion associated with the small-scale cyclone enhanced the latent heat flux from the sea, thereby helping to maintain the development of deep convection and so induc- ing further cyclone deepening by diabatic heating. This scenario represents an air-sea interaction instability feedback mechanism. The primary role of the sea as a source of heat and moisture in this particular event is highlighted by performing a sensitiv- ity analysis of the cyclone formation to different SST's. Thus, the interaction of the upper-level anomaly and the heat fluxes from the sea emerges as the main agent for the genesis and evolution of the small quasi-tropical cyclone.

Homar, V.; Romero, R.; Stensrud, D. J.; Ramis, C.; Alonso, S.

217

The impacts of tropical cyclones on the net carbon balance of eastern US forests (1851-2000)  

NASA Astrophysics Data System (ADS)

In temperate forests of the eastern US, tropical cyclones are a principal agent of catastrophic wind damage, with dramatic impacts on the structure and functioning of forests. Substantial progress has been made to quantify forest damage and resulting gross carbon emissions from tropical cyclones. However, the net effect of storms on the carbon balance of forests depends not only on the biomass lost in single events, but also on the uptake during recovery from a mosaic of past events. This study estimates the net impacts of tropical cyclones on the carbon balance of US forests over the period 1851-2000. To track both disturbance and recovery and to isolate the effects of storms, a modeling framework is used combining gridded historical estimates of mortality and damage with a mechanistic model using an ensemble approach. The net effect of tropical cyclones on the carbon balance is shown to depend strongly on the spatial and temporal scales of analysis. On average, tropical cyclones contribute a net carbon source over latter half of the 19th century. However, throughout much of the 20th century a regional carbon sink is estimated resulting from periods of forest recovery exceeding damage. The large-scale net annual flux resulting from tropical cyclones varies by up to 50 Tg C yr-1, an amount equivalent to 17%-36% of the US forest carbon sink.

Fisk, J. P.; Hurtt, G. C.; Chambers, J. Q.; Zeng, H.; Dolan, K. A.; Negrón-Juárez, R. I.

2013-12-01

218

An Evaluation of QuikSCAT data over Tropical Cyclones as Determined in an Operational Environment  

NASA Astrophysics Data System (ADS)

QuikSCAT data over all global tropical cyclones were examined during the past 3 1/2 years in conjunction with the development of a user¡_s guide to the forecasters at the Joint Typhoon Warning Center, Pearl Harbor, Hawaii. The active microwave scatterometer has greatly enhanced the forecaster's ability to evaluate surface winds over the data poor regions of the tropical oceans. The QuikSCAT scatterometer¡_s unique ability to provide both wind speed and direction on a nearly bi-daily basis has greatly increased the forecaster¡_s near real-time knowledge of tropical cyclone genesis, intensification potential, outer wind structure, and a ¡rminimum estimate¡_ for a tropical cyclone¡_s maximum sustained winds. Scatterometer data were compared with data available to the forecasters in a near real-time environment including ship, land and buoy reports. In addition, comparisons were also made with aircraft measurements (for Atlantic and East Pacific systems), numerical weather model wind fields, and various remote sensing techniques. Wind speeds were found to be extremely useful, especially for the radius of gale force winds. However, in rain-contaminated areas, light winds were often greatly overestimated while in heavy winds, wind speeds were often quite reasonable if not slightly underestimated. The largest issues are still focused on the correct wind direction selection. In these cases, rain-flagged wind vector cells greatly affected the results from the direction ambiguity selection procedure. The ambiguity selection algorithm often had difficulties resolving a circulation center when large areas of the tropical cyclone¡_s center were flagged. Often a block of winds would occur perpendicular to the swath irregardless of the circulation¡_s position. These winds caused considerable confusion for the operational forecasters. However, it was determined that in many cases, an accurate center position could still be obtained by using methods to incorporate the more accurate wind speeds and the outer wind field vectors that were not as seriously affected. Quantitative results and comparisons will be shown in this presentation. In addition, guides to the operational forecasters to determine system centers inspite of the ambiguity selection problems will also be discussed.

Hawkins, J. D.; Edson, R. T.

2001-12-01

219

Stratospheric and mesospheric concentric gravity waves over tropical cyclone Mahasen: Joint AIRS and VIIRS satellite observations  

NASA Astrophysics Data System (ADS)

We report on the first simultaneous spaceborne observations of concentric gravity wave patterns in the stratosphere and mesosphere over the Indian Ocean excited by Tropical Cyclone Mahasen. On the nights of 13-14 May 2013, concentric ring patterns in nightglow were observed in close-proximity to Mahasen by the Day/Night Band (DNB) of the Visible/Infrared Imager/Radiometer Suite (VIIRS) on the Suomi NPP satellite. The waves exhibited horizontal wavelengths of 40-60 km. On 13 May 2013, long concentric waves of ~500 km wavelength were also seen west of India, far away (~1500 km) from their estimated center near Mahasen. Concentric gravity waves in the stratosphere were observed nearly simultaneously by the Atmospheric Infrared Sounder on the Aqua satellite. These multi-level observations provide a clearer picture of the complex three-dimensional structure of tropical cyclone-generated gravity waves than a single instrument alone.

Yue, Jia; Miller, Steven D.; Hoffmann, Lars; Straka, William C.

2014-11-01

220

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

NASA Technical Reports Server (NTRS)

During the 1975, 1976 and 1977 North Atlantic hurricane seasons, NOAA/NESS and NASA/GSFC conducted a cooperative program to determine the best resolution and frequency now available from satellite images for deriving winds to study and forecast tropical cyclones. High spatial and temporal resolution satellite imagery made it feasible to provide a large number of lower and upper tropospheric winds which can be obtained by tracking clouds within 650 km of tropical cyclone centers. Up to 10 (5) times as many low-level winds were derived from images spaced at 3 or 7.5 min intervals as from those at 30 min (15 min) intervals. Rapid-scan full-resolution IR and visible images minimized the 'erroneous' winds derived by tracking cloud elements that propagate by growing on one side and dissipating on the other and by tracking repetitive patterns that provided ambiguous indications of direction of movement.

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

1979-01-01

221

Concept of spinsonde for multi-cycle measurement of vertical wind profile of tropical cyclones  

E-print Network

Tropical cyclones and cyclogenesis are active areas of research. Chute-operated dropsondes jointly developed by NASA and NCAR are capable of acquiring high resolution vertical wind profile of tropical cyclones. This paper proposes a chute-free vertical retardation technique (termed as spinsonde) that can accurately measure vertical wind profile. Unlike the expendable dropsondes, the spinsonde allows multi-cycle measurement to be performed within a single flight. Proof of principle is demonstrated using a simulation software and results indicate that the GPS ground speed correlates with the wind speeds to within +/-5 km/h. This technique reduces flying weight and increases payload capacity by eliminating bulky chutes. Maximum cruising speed (Vh) achieved by the spinsonde UAV is 372 km/h.

Poh, Chung-How

2014-01-01

222

The impact of verification area design on tropical cyclone targeted observations based on the CNOP method  

Microsoft Academic Search

This study investigated the impact of different verification-area designs on the sensitive areas identified using the conditional\\u000a nonlinear optimal perturbation (CNOP) method for tropical cyclone targeted observations. The sensitive areas identified using\\u000a the first singular vector (FSV) method, which is the linear approximation of CNOP, were also investigated for comparison.\\u000a By analyzing the validity of the sensitive areas, the proper

Feifan Zhou; Mu Mu

2011-01-01

223

A statistical forecast model for Tropical Cyclone Rainfall and flood events for the Hudson River  

NASA Astrophysics Data System (ADS)

Tropical Cyclones (TCs) lead to potentially severe coastal flooding through wind surge and also through rainfall-runoff processes. There is growing interest in modeling these processes simultaneously. Here, a statistical approach that can facilitate this process is presented with an application to the Hudson River Basin that is associated with the New York City metropolitan area. Three submodels are used in sequence. The first submodel is a stochastic model of the complete life cycle of North Atlantic (NA) tropical cyclones developed by Hall and Yonekura (2011). It uses archived data of TCs throughout the North Atlantic to estimate landfall rates at high geographic resolution as a function of the ENSO state and of sea surface temperature (SST). The second submodel translates the attributes of a tropical cyclone simulated by the first model to rainfall intensity at selected stations within the watershed of Hudson River. Two different approaches are used and compared: artificial neural network (ANN) and k-nearest neighbor (KNN). Finally, the third submodel transforms, once again, by using an ANN approach and KNN, the rainfall intensities, calculated for the ensemble of the stations, to the streamflows at specific points of the tributaries of the Hudson River. These streamflows are to be used as inputs in a hydrodynamic model that includes storm surge surge dynamics for the simulation of coastal flooding along the Hudson River. Calibration and validation of the model is carried out by using, selected tropical cyclone data since 1950, and hourly station rainfall and streamflow recorded for such extreme events. Four stream gauges (Troy dam, Mohawk River at Cohoes, Mohawk River diversion at Crescent Dam, Hudson River above lock one nr Waterford), a gauge from a tributary in the lower Hudson River, and over 20 rain gauges are used. The performance of the proposed model as tool for storm events is then analyzed and discussed.

Cioffi, Francesco; Conticello, Federico; Hall, Thimoty; Lall, Upmanu; Orton, Philip

2014-05-01

224

Does Tropical Cyclone Modification Make Sense? A Decision-Analytic Assessment  

Microsoft Academic Search

Since the demise of project Stormfury in 1983, little attention has been devoted to the possibility of intentionally modifying tropical cyclones (TC). However, following Hurricane Katrina and three other Category 5 hurricanes (Emily, Rita, and Wilma), which together resulted in at least 2,280 deaths and over $120-billion in damages (Blake et al., 2007), the U.S. Department of Homeland Security (DHS)

K. Klima; M. G. Morgan; I. Grossmann

2009-01-01

225

Spatial and Spatiotemporal Projection Pursuit Techniques to Predict the Extratropical Transition of Tropical Cyclones  

Microsoft Academic Search

A multistage projection pursuit (PP) approach is applied to the classification of tropical cyclones (TCs) during extratropical transition (ET) using 500-hPa Navy Operational Global Atmospheric Prediction System (NOGAPS) geopotential height analyses. PP algorithms reduce the dimensionality of the high-dimensional data while minimizing the loss of information that discriminates among classes of ET types. In this paper, a prediction system is

Oguz Demirci; J. Scott Tyo; Elizabeth A. Ritchie

2007-01-01

226

Tropical cyclone strikes at the coastal cities of China from 1949 to 2008  

Microsoft Academic Search

The spatiotemporal features of tropical cyclone strikes from 1949 to 2008 at 49 coastal cities of China are investigated in\\u000a this study. The cities in Hainan, Guangdong, and Taiwan have high strike frequencies, with the severest and most frequent\\u000a average strikes found in Taiwan. In Hainan, strike clusters appear in the mid-1950s, the early 1960s and 1970s, and the late

Qingqing Li; Yihong Duan

2010-01-01

227

The effect of surface friction on the development of tropical cyclones  

Microsoft Academic Search

When tropical cyclones (hereafter referred as TCs) are over the ocean, surface friction plays a dual role in the development\\u000a of TCs. From the viewpoint of water vapor supply, frictional convergence and Ekman pumping provide a source of moisture for\\u000a organized cumulus convection and is propitious to the spin-up of TCs. On the other hand, surface friction leads to a

Juan Fang; Jianping Tang; Rongsheng Wu

2009-01-01

228

ENSO and Western North Pacific tropical cyclone activity simulated in a CGCM  

Microsoft Academic Search

A high-resolution (T213) coupled ocean–atmosphere general circulation model (CGCM) has been used to examine the relationship\\u000a between El Niño\\/Southern Oscillation (ENSO) and tropical cyclone (TC) activity over the western North Pacific (WNP). The model\\u000a simulates ENSO-like events similar to those observed, though the amplitude of the simulated Niño34 sea surface temperature\\u000a (SST) anomaly is twice as large as observed. In

Satoshi Iizuka; Tomonori Matsuura

2008-01-01

229

Influence of the Global Warming on Tropical Cyclone Climatology: An Experiment with the JMA Global Model  

Microsoft Academic Search

The influence of the global warming on tropical cyclones has been examined using a high resolution AGCM. Two ten-year integrations were performed with the JMA global model at T106 horizontal resolu- tion. For the control experiment, the observed SST for the period 1979-1988 is prescribed, while for the doubling CO2 (2 ? CO2) experiment, SST anomaly due to the global

Masato SUGI; Akira NODA; Nobuo SATO

2002-01-01

230

Barotropic process contributing to the formation and growth of tropical cyclone Nargis  

NASA Astrophysics Data System (ADS)

This study reveals the barotropic dynamics associated with the formation and growth of tropical cyclone Nargis in 2008, during its formation stage. Strong equatorial westerlies occurred over the southern Bay of Bengal in association with the arrival of an intraseasonal westerly event during the period 22-24 April 2008. The westerlies, together with strong tropical-subtropical easterlies, constituted a large-scale horizontal shear flow, creating cyclonic vorticity and thereby promoting the incipient disturbance that eventually evolved into Nargis. This basic zonal flow in the lower troposphere was barotropically unstable, with the amplified disturbance gaining more kinetic energy from the easterly jet than from the westerly jet during 25-26 April. This finding suggests that more attention should be paid to the unstable easterly jet when monitoring and predicting the development of tropical cyclones. Energetics analyses reveal that barotropic energy conversion by the meridional gradient of the basic zonal flow was indeed an important energy source for the growth of Nargis.

Mao, Jiangyu; Wu, Guoxiong

2011-05-01

231

Tropical Cyclone Intensification from Asymmetric Convection: Energetics and Efficiency  

E-print Network

. 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 to the azimuthally averaged heating. The symmetric response to the purely asymmetric part of the heating was found

Nolan, David S.

232

Tropical cyclones in a regional coupled ocean-atmosphere model of the South Pacific Convergence Zone  

NASA Astrophysics Data System (ADS)

The South Pacific Convergence Zone (SPCZ) is the most powerful convective machine of the Southern Hemisphere. Extreme weather and water resources of numerous vulnerable islands depend on its behavior. In particular, the SPCZ experiences about 15% of global annual cyclone occurrence. Yet, understanding the coupled ocean-atmosphere dynamics of the SPCZ is a challenge that is still to be met, especially in view of the strong known biases of climate models in this region. Tropical cyclone development and fate are intrinsically linked to air-sea coupling as they derive their energy from air-sea heat and moisture fluxes. Most notably, as cyclones develop, they induce sea surface cooling on their track that provides a negative feedback on their intensity. The objective of the present study is to quantify the capacity of air-sea coupling to control cyclonic intensity in the SPCZ. It fills a gap in the current modeling literature between coarse resolution coupled climate models and short-term studies. For this study, we implemented a regional coupled model of the SPCZ at 35 km resolution, based on the mesoscale atmospheric model WRF (Weather Research and Forecast) and oceanic model ROMS (Regional Oceanic Modeling System). Interannual boundary forcing is applied in a 10-year long simulation. The SPCZ behavior in the coupled system is shown to be realistic in terms of large-scale circulation, and patterns and magnitude of precipitation and air-sea fluxes. The surface drag coefficients appear among the most sensitive parameters in the coupled system. The residual coupling effect is analyzed through comparison between the coupled simulation and an uncoupled atmospheric simulation. Significant statistical changes induced by coupling as expressed in spatial distribution, seasonal variability and intensity distribution are evidenced in this comparison at both cyclonic and climatological scales. We also estimate the changes in stochastic processes that affect the interannual variability of cyclonic activity.

Jullien, S.; Marchesiello, P.; Menkes, C.; Lefevre, J.; Lengaigne, M.

2012-12-01

233

Role of Sensible and Latent Heat Fluxes from the Ocean in the Genesis of Tropical Cyclone Nargis (2008)  

NASA Astrophysics Data System (ADS)

On May 2, 2008, Tropical Cyclone Nargis killed over 130,000 people in southern Myanmar making it the 8th deadliest cyclone of all time. A better understanding of the mechanisms in the early stages of development of tropical cyclones, such as the role of latent and sensible heat fluxes from the ocean, could help forecast modelers better understand the physics of the cyclogenesis, improve the model forecasts and ultimately gain a greater lead time in detecting and predicting cyclones. We conducted two experiments using the Weather Research and Forecast (WRF) model version 3.3.1 to determine the impact of surface fluxes on the genesis of Cyclone Nargis during a 60-hour forecast. The two experiments included: a control run (CNTRL), where the model forecast had full physics, including sensible and latent heat fluxes from the surface, and a no flux run (NOFLX), which turned off both surface sensible heat and latent heat fluxes. The CNTRL produced a strong cyclone, with a maximum wind of 65 knots (33.4 m/s) and a minimum pressure of 955 hPa. The NOFLX produced a weak cyclone with a maximum wind of 25 knots (12.9 m/s) and a minimum pressure of 1002 hPa. Thus major factors in the genesis of Cyclone Nargis were the surface latent and sensible heat fluxes over the ocean, where the sea-surface temperature was above normal.

Almanza, V. D.; Anthes, R. A.; Chen, S.; Kuo, Y.; Wang, C.; Schreiner, W. S.; Hunt, D.

2012-12-01

234

Central American Gyres, Tropical Cyclones, and Heavy Eastern U.S. Rainfall  

NASA Astrophysics Data System (ADS)

Between late summer and mid-autumn, broad low-level cyclonic circulations with spatial scales of 1000-2000 km can develop over Central America on time scales of 1-2 days and persist for 3-5 days. These broad cyclonic circulation regions, which hereafter we will call gyres, can absorb westward-moving tropical cyclones (TCs) from the east (e.g., Matthew in September 2010), disgorge cyclonic circulations to the northeast that later develop into TCs (e.g., Nicole in September 2010), interact with remnant southward-moving cold fronts to encourage weak TC development (e.g., TC Nate in October 2011), or enable weak eastern Pacific tropical depressions (TDs) to make landfall in Central America (e.g., TD 12-E in October 2011). A distinguishing feature of a Central American gyre is that it can be directly associated with exceptionally heavy rainfall and damaging regional flooding, such as occurred in conjunction with the landfall of TD 12-E and TC Nate. Similarly, a deep poleward tropical moisture transport from a Central American gyre in response to amplified midlatitude flow can lead to flooding rains in midlatitudes such as occurred along the Atlantic coast in conjunction with TC Lee in September 2011. This presentation will focus on the large-scale flow contribution to the formation of a well-defined Central American gyre in late September 2010 during the PREDICT field experiment and the subsequent impact of the gyre on the midlatitude flow and weather over eastern North America. The gyre formed when a strong east-west oriented cyclonic shear zone that separated anomalous tropical westerlies in the eastern Pacific from anomalous tropical easterlies over the Caribbean and North Atlantic was disrupted by northerly flow across the Isthmus of Tehuantepec gap (Chivela Pass) into the tropical Pacific. Initially, anomalous easterly flow from the Caribbean that was deflected southward by higher terrain to the west provided the initial source of northerly flow through the gap. Subsequently, northerly winds west of TC Matthew as the storm made landfall in Central America provided a renewed source of gap flow. Finally, a terrain-channeled northerly cool surge developed through the gap in the later stages of the gyre life cycle. TC-induced anticyclonic wave breaking over the western Pacific, subsequent downstream Rossby wave development, and formation of a meridionally elongated trough over central North America contributed to cool surge formation. Gyre formation allowed cyclonic vorticity and tropical moisture to become concentrated over Central America. Gyre-TC interactions and gyre-induced poleward tropical moisture surges will be discussed in conjunction with the "birth" of TC Nicole and subsequent very heavy rains along the U.S. East Coast.

Bosart, L. F.; Griffin, K. S.; Papin, P. P.; Torn, R. D.

2012-12-01

235

Numerical modeling of wind waves generated by tropical cyclones using moving grids  

NASA Astrophysics Data System (ADS)

A version of the WAVEWATCH III wave model featuring a continuously moving spatial grid is presented. The new model option/version is intended for research into wind waves generated by tropical cyclones in deep water away from the coast. The main advantage of such an approach is that the cyclones can be modeled with spatial grids that cover much smaller areas than conventional fixed grids, making model runs with high spatial resolution more economically feasible. The model modifications necessary are fairly trivial. Most complications occur due to the Garden Sprinkler effect (GSE) and methods used to mitigate it. The basic testing of the model is performed using idealized wind fields consisting of a Rankine vortex. The model is also applied to hurricane Lili in the Gulf of Mexico in October 2002. The latter application shows that the moving grid approach provides a natural way to deal with hurricane wind fields that have a high-resolution in space, but a low resolution in time. Although the new model version is originally intended for tropical cyclones, it is suitable for high-resolution modeling of waves due to any moving weather pattern.

Tolman, Hendrik L.; Alves, Jose-Henrique G. M.

236

Impact of tropical cyclones on aerosol properties over urban region of Hyderabad, India  

NASA Astrophysics Data System (ADS)

Fierce tropical cyclones occur in India during the pre-monsoon (spring), early monsoon (early summer), or post-monsoon (fall) periods. Originating in both the Bay of Bengal and the Arabian Sea, tropical cyclones often attain velocities of more than 100 kmh-1 and are notorious for causing intense rain and tidal waves as they cross the Indian coast. Cyclones are associated with heavy rainfall, gusty winds, and sometimes, storm surges. In the present study, we have analyzed the changes in aerosol properties at Hyderabad, India, associated with very severe cyclonic storm "Mala" occurred during the last week of April, 2006 over the Central-Eastern part of the Bay of Bengal centered near Lat. 16.0 N and Long. 93.0 E, at 18:00 UTC on 28th April 2006, about 500 Km North of Portblair. This tropical cyclone, packing winds of 240 km/h, slammed into Myanmar on 28th April and 29th April destroying hundreds of houses, two beach resorts and at least five factories as per the reports of the Kyemon daily paper and the International Federation of the Red Cross. Cyclone "Mala" is described as the most severe cyclone in the Bay of Bengal after the 1999 Orissa Super Cyclone. The measurements for the case study were carried out in the premises of the National Remote Sensing Centre (NRSC) campus at Balanagar (17o.28' N and 78o.26' E) located within the Hyderabad urban center during cyclone period. Synchronous and continuous observations of columnar Aerosol Optical Depth (AOD) were carried out using a handheld multi-channel sun-photometer (Microtops-II, Solar Light Co., USA) at six wavelength bands centered around 380, 440, 500, 675, 870 and 1020 nm. Continuous measurements of particulate matter (PM) grain-size distribution were performed with the GRIMM aerosol spectrometer, model 1-108. The cyclone "Mala" over the Bay of Bengal occurred during 26-29 April, 2006, struck the coast of Myanmar with winds of 115 mph (185 kmh-1), causing severe damage and loss of human life on 29 April, 2006. Initially the depression was moving northwest and on 25 April it changed its direction and accelerated towards north and after northeast resulting in remarkable wind direction changes. As the cyclone moved towards the Myanmar coast on 29 and 30 April, the low-level convergence turned to northwesterly, pulling air from the northern Indian landscapes. This caused an increase in wind speed over the entire Bay of Bengal. The intensity of the cyclonic activity affected continental India on 28 and 29 April. On that day the wind field was dominated by a northwesterly flow from Indian continent towards the Bay of Bengal, which lifted a lot of mineral dust particles from the Indian arid landscapes. This is further confirmed from the analysis of Terra-MODIS image on 29 April, where the dust plumes over the Bay of Bengal can be clearly detected. The variation of the daily mean particulate-matter load measured by the GRIMM instrument showed nearly a two-fold increase in particulate-mass concentrations during the intense cyclone period (28th and 29th April). This is attributed to the increase in surface winds caused by the cyclonic activity, strongly associated with lifting of coarse-mode aerosols from the landscapes neighboring Hyderabad. Also, from the large standard deviations it is concluded that the diurnal pattern of the PMx concentrations are highly variable during the cyclonic activity, probably caused by the frequent and sharp changes in wind speed and direction accompanying it. The day-to-day variation of AOD500 and Ångström exponent ? were also analysed. Contrary to the PMx concentrations, the AOD500 values showed remarkable decrease during the cyclone period. This decrease can be as high as 44% between the pre and during cyclone days (25th and 28th April), respectively and 41% between 28 and 30 April. These large variations in aerosol load are mainly attributed to the changes in wind speed and direction as well as the air mass trajectories, bringing marine air masses over the region on 28th April. Despite the uplifting of soil pa

Kharol, Shailesh Kumar; Badarinath, K. V. S.; Rani Sharma, Anu; Krishna Prasad, V.; Kaskaoutis, Dimitrios G.; Nastos, Panagiotis T.; Kambezidis, Harry D.

2010-05-01

237

Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tropical cyclone-induced storm surges  

NASA Astrophysics Data System (ADS)

The incidence of major storm surges in the last decade have dramatically emphasized the immense destructive capabilities of extreme water level events, particularly when driven by severe tropical cyclones. Given this risk, it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood and erosion management, engineering and for future land-use planning and to ensure the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. Australia has a long history of coastal flooding from tropical cyclones. Using a novel integration of two modeling techniques, this paper provides the first estimates of present day extreme water level exceedance probabilities around the whole coastline of Australia, and the first estimates that combine the influence of astronomical tides, storm surges generated by both extra-tropical and tropical cyclones, and seasonal and inter-annual variations in mean sea level. Initially, an analysis of tide gauge records has been used to assess the characteristics of tropical cyclone-induced surges around Australia. However, given the dearth (temporal and spatial) of information around much of the coastline, and therefore the inability of these gauge records to adequately describe the regional climatology, an observationally based stochastic tropical cyclone model has been developed to synthetically extend the tropical cyclone record to 10,000 years. Wind and pressure fields derived for these synthetically generated events have then been used to drive a hydrodynamic model of the Australian continental shelf region with annual maximum water levels extracted to estimate exceedance probabilities around the coastline. To validate this methodology, selected historic storm surge events have been simulated and resultant storm surges compared with gauge records. Tropical cyclone induced exceedance probabilities have been combined with estimates derived from a 61-year water level hindcast described in a companion paper to give a single estimate of present day extreme water level probabilities around the whole coastline of Australia. Results of this work are freely available to coastal engineers, managers and researchers via a web-based tool (www.sealevelrise.info). The described methodology could be applied to other regions of the world, like the US east coast, that are subject to both extra-tropical and tropical cyclones.

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

2014-01-01

238

Evaluating probabilistic decadal forecasts of Northern Hemisphere extra-tropical cyclone frequencies  

NASA Astrophysics Data System (ADS)

Mid-latitudinal cyclones are a key factor for understanding regional anomalies of primary meteorological parameters, such as temperature, surface wind speed or precipitation. Extreme cyclones potentially cause tremendous impacts on society and economy, e.g. by enormous wind-storm induced damages. Based on an ensemble prediction experiment with 41 annually initialised (1961-2001) hindcasts, as part of the German MiKlip-initiative for decadal prediction, this study evaluates a single-model decadal forecast system (MPI-ESM-LR). It analyses, whether the forecast system can provide skillful probabilistic three-category forecasts (enhanced, normal or decreased) of extra-tropical winter (ONDJFM) cyclone frequencies over the northern hemisphere with lead times from one year up to a decade. Thus, it will be analysed whether the MiKlip-system is of additional value compared to climatological forecasts and uninitialised climate projections. It is shown, that these predictions exhibit significant skill, mainly over the North Atlantic and Pacific for lead times of 2-5 years. Skill for the subset of intense (strongest 25% according to laplacian of SLP) cyclones is generally higher than for the full set of all detected systems.A comparison of decadal predictions from different initialisation strategies indicates systematic differences for some lead times and regions. Additional parameters (e.g. air temperature, SST, and geopotential height) and indices of large-scale variability modes (e.g. NAO and PNA) are analysed for a better understanding of the underlying mechanisms of cyclone frequency modification and thus potential sources of skill.

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

2014-05-01

239

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

Microsoft Academic Search

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

Patrick J. Grant

1981-01-01

240

Predicting Tropical Cyclogenesis with a Global Mesoscale Model: Hierarchical Multiscale Interactions During the Formation of Tropical Cyclone Nargis(2008)  

NASA Technical Reports Server (NTRS)

Very severe cyclonic storm Nargis devastated Burma (Myanmar) in May 2008, caused tremendous damage and numerous fatalities, and became one of the 10 deadliest tropical cyclones (TCs) of all time. To increase the warning time in order to save lives and reduce economic damage, it is important to extend the lead time in the prediction of TCs like Nargis. As recent advances in high-resolution global models and supercomputing technology have shown the potential for improving TC track and intensity forecasts, the ability of a global mesoscale model to predict TC genesis in the Indian Ocean is examined in this study with the aim of improving simulations of TC climate. High-resolution global simulations with real data show that the initial formation and intensity variations of TC Nargis can be realistically predicted up to 5 days in advance. Preliminary analysis suggests that improved representations of the following environmental conditions and their hierarchical multiscale interactions were the key to achieving this lead time: (1) a westerly wind burst and equatorial trough, (2) an enhanced monsoon circulation with a zero wind shear line, (3) good upper-level outflow with anti-cyclonic wind shear between 200 and 850 hPa, and (4) low-level moisture convergence.

Shen, B.-W.; Tao, W.-K.; Lau, W. K.; Atlas, R.

2010-01-01

241

Predicting tropical cyclogenesis with a global mesoscale model: Hierarchical multiscale interactions during the formation of tropical cyclone Nargis (2008)  

NASA Astrophysics Data System (ADS)

Very severe cyclonic storm Nargis devastated Burma (Myanmar) in May 2008, caused tremendous damage and numerous fatalities, and became one of the 10 deadliest tropical cyclones (TCs) of all time. To increase the warning time in order to save lives and reduce economic damage, it is important to extend the lead time in the prediction of TCs like Nargis. As recent advances in high-resolution global models and supercomputing technology have shown the potential for improving TC track and intensity forecasts, the ability of a global mesoscale model to predict TC genesis in the Indian Ocean is examined in this study with the aim of improving simulations of TC climate. High-resolution global simulations with real data show that the initial formation and intensity variations of TC Nargis can be realistically predicted up to 5 days in advance. Preliminary analysis suggests that improved representations of the following environmental conditions and their hierarchical multiscale interactions were the key to achieving this lead time: (1) a westerly wind burst and equatorial trough, (2) an enhanced monsoon circulation with a zero wind shear line, (3) good upper-level outflow with anti-cyclonic wind shear between 200 and 850 hPa, and (4) low-level moisture convergence.

Shen, B.-W.; Tao, W.-K.; Lau, W. K.; Atlas, R.

2010-07-01

242

An evaluation of the real-time tropical cyclone forecast skill of the Navy Operational Global Atmospheric Prediction System in the western North Pacific  

NASA Technical Reports Server (NTRS)

The paper evaluates the meteorological quality and operational utility of the Navy Operational Global Atmospheric Prediction System (NOGAPS) in forecasting tropical cyclones. It is shown that the model can provide useful predictions of motion and formation on a real-time basis in the western North Pacific. The meterological characteristics of the NOGAPS tropical cyclone predictions are evaluated by examining the formation of low-level cyclone systems in the tropics and vortex structure in the NOGAPS analysis and verifying 72-h forecasts. The adjusted NOGAPS track forecasts showed equitable skill to the baseline aid and the dynamical model. NOGAPS successfully predicted unusual equatorward turns for several straight-running cyclones.

Fiorino, Michael; Goerss, James S.; Jensen, Jack J.; Harrison, Edward J., Jr.

1993-01-01

243

An evaluation of the real-time tropical cyclone forecast skill of the Navy Operational Global Atmospheric Prediction System in the western North Pacific  

SciTech Connect

The paper evaluates the meteorological quality and operational utility of the Navy Operational Global Atmospheric Prediction System (NOGAPS) in forecasting tropical cyclones. It is shown that the model can provide useful predictions of motion and formation on a real-time basis in the western North Pacific. The meterological characteristics of the NOGAPS tropical cyclone predictions are evaluated by examining the formation of low-level cyclone systems in the tropics and vortex structure in the NOGAPS analysis and verifying 72-h forecasts. The adjusted NOGAPS track forecasts showed equitable skill to the baseline aid and the dynamical model. NOGAPS successfully predicted unusual equatorward turns for several straight-running cyclones. 35 refs.

Fiorino, M.; Goerss, J.S.; Jensen, J.J.; Harrison, E.J. Jr. (NASA, Goddard Space Flight Center, Greenbelt, MD (United States) Naval Research Lab., Monterey, CA (United States) Fleet Numerical Oceanography Center, Monterey, CA (United States) ARC Professional Services Group, Inc., Landover, MD (United States))

1993-03-01

244

Tropical Cyclones and Ice Cores: Developing a Long Term Perspective  

NASA Astrophysics Data System (ADS)

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

Urmann, D.

2006-12-01

245

Analysis of North Atlantic tropical cyclone intensify change using data mining  

NASA Astrophysics Data System (ADS)

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 study aims to tackle two factors that account for the underperformance of current TC intensity forecasts: (1) inadequate observations of TC structures, and (2) deficient understanding of the underlying physical processes governing TC intensification. To tackle the problem of inadequate observations of TC structures, efforts have been made to extract vertical and horizontal structural parameters of latent heat release from Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data products. A case study of Hurricane Isabel (2003) was conducted first to explore the feasibility of using the 3D TC structure information in predicting TC intensification. Afterwards, several structural parameters were extracted from 53 TRMM PR 2A25 observations on 25 North Atlantic TCs during the period of 1998 to 2003. A new generation of multi-correlation data mining algorithm (Apriori and its variations) was applied to find roles of the latent heat release structure in TC intensification. The results showed that the buildup of TC energy is indicated by the height of the convective tower, and the relative low latent heat release at the core area and around the outer band. Adverse conditions which prevent TC intensification include the following: (1) TC entering a higher latitude area where the underlying sea is relative cold, (2) TC moving too fast to absorb the thermal energy from the underlying sea, or (3) strong energy loss at the outer band. When adverse conditions and amicable conditions reached equilibrium status, tropical cyclone intensity would remain stable. The dataset from Statistical Hurricane Intensity Prediction Scheme (SHIPS) covering the period of 1982-2003 and the Apriori-based association rule mining algorithm were used to study the associations of underlying geophysical characteristics with the intensity change of tropical cyclones. The data have been stratified into 6 TC categories from tropical depression to category 4 hurricanes based on their strength. The result showed that the persistence of intensity change in the past and the strength of vertical shear in the environment are the most prevalent factors for all of the 6 TC categories. Hyper-edge searching had found 3 sets of parameters which showed strong intramural binds. Most of the parameters used in SHIPS model have a consistent "I-W" relation over different TC categories, indicating a consistent function of those parameters in TC development. However, the "I-W" relations of the relative momentum flux and the meridional motion change from tropical storm stage to hurricane stage, indicating a change in the role of those two parameters in TC development. Because rapid intensification (RI) is a major source of errors when predicting hurricane intensity, the association rule mining algorithm was performed on RI versus non-RI tropical cyclone cases using the same SHIPS dataset. The results had been compared with those from the traditional statistical analysis conducted by Kaplan and DeMaria (2003). The rapid intensification rule with 5 RI conditions proposed by the traditional statistical analysis was found by the association rule mining in this study as well. However, further analysis showed that the 5 RI conditions can be replaced by another association rule using fewer conditions but with a higher RI probability (RIP). This means that the rule with all 5 constraints found by Kaplan and DeMaria is not optimal, and the association rule mining technique can find a rule with fewer constraints yet fits more RI cases. The further analysis with the highest RIPs over different numbers of conditions has demonstrated that the interactions among multiple factors are responsible for the RI process of T

Tang, Jiang

246

Spatial relationships between tropical cyclone frequencies and population densities in Haiti since the 19th century  

NASA Astrophysics Data System (ADS)

The second edition of the United Nations Global Assessment Report on Disaster Risk Reduction in 2011 outlined that the worldwide physical exposure to tropical cyclones increased by 192 per cent between 1970 and 2010. For the past 160 years, the Republic of Haiti has experienced numerous tropical storms and hurricanes which may have directly effected the country's development path. However, statistical data regarding storm frequencies and population densities in space and time show that the population's exposure in Haiti may have more negatively influenced its development than the actual number of storms and hurricanes. Haitians, in particular, those living in urban areas have been exposed to much higher tropical cyclone hazards than rural areas since the second half of the 20th century. Specifically, more storms made landfall in regions of accelerated migration/urbanization, such as, in departments Ouest, Artibonite, Nord, and Nord-Ouest with Haiti's four largest cities Port-au-Prince, Gonaives, Cap-Haitien and Port-de-Paix.

Klose, C. D.

2011-12-01

247

Journal of the Meteorological Society of Japan, Vol. 80, No. 3, pp. 403--418, 2002 403 Interannual Variation of Tropical Cyclone Activity  

E-print Network

, USA and Pao-Shin CHU Department of Meteorology, School of Ocean and Earth Science and Technology of tropical cyclones, which includes tropical storms and hurricanes, is high. For the period 1966 with the increased cyclone frequency in the CNP for an ENHS composite. Furthermore, a majority of initial detection

Hawai'i at Manoa, University of

248

Statistical Aspects of North Atlantic Basin Tropical Cyclones During the Weather Satellite Era, 1960-2013: Part 1  

NASA Technical Reports Server (NTRS)

A tropical cyclone is described as a warm-core, nonfrontal, synoptic-scale system that originates over tropical or subtropical waters, having organized deep convection and closed surface wind circulation (counterclockwise in the Northern Hemisphere) about a well defined center. When its sustained wind speed equals 34-63 kt, it is called a tropical (or subtropical) storm and is given a name (i.e., alternating male and female names, beginning in 1979); when its sustained wind speed equals 64-95 kt, it is called a hurricane (at least in the Eastern Pacific and North Atlantic basin); and when its sustained wind speed equals 96 kt or higher, it is called an intense or major hurricane (i.e., categories 3-5 on the Saffir-Simpson Hurricane Wind Scale). Although tropical cyclones have been reported and described since the voyages of Columbus, a detailed record of their occurrences extends only from 1851 to the present, with the most reliable portion extending only from about 1945 to the present, owing to the use of near-continuous routine reconnaissance aircraft monitoring flights and the use of satellite imagery (beginning in 1960; see Davis). Even so, the record may still be incomplete, possibly missing at least one tropical cyclone per yearly hurricane season, especially prior to the use of continuous satellite monitoring. In fact, often an unnamed tropical cyclone is included in the year-end listing of events at the conclusion of the season, following post-season analysis (e.g., as happened in 2011 and 2013, each having one unnamed event). In this two-part Technical Publication (TP), statistical aspects of the North Atlantic basin tropical cyclones are examined for the interval 1960-2013, the weather satellite era. Part 1 examines some 25 parameters of tropical cyclones (e.g., frequencies, peak wind speed (PWS), accumulated cyclone energy (ACE), etc.), while part 2 examines the relationship of these parameters against specific climate-related factors. These studies are a continuation of nearly two decades of previous tropical cyclone-related investigations.

Wilson, Robert M.

2014-01-01

249

An analysis of the multiscale nature of tropical cyclone activities in June 2004: Climate background  

NASA Astrophysics Data System (ADS)

A record-breaking five tropical cyclones (TCs) formed in June 2004 in the western North Pacific (WNP), where June is normally a transition month to the typhoon season and therefore sensitive to climate oscillations. This special month (June 2004) was an unusual period in the developing stage of a warm (El Niño) episode and a strong convective phase of the Madden-Julian Oscillation (MJO). Such climate background is shown to provide large-scale favorable circulations for TC formation: the warm sea surface temperature anomalies (SSTAs) associated with developing El Niño and convective heating of the MJO to jointly induce weaker easterly trade winds and a large-scale cyclonic circulation anomaly in the WNP. A space-time filtering of the outgoing longwave radiation (OLR) and 850 hPa wind fields is performed to identify the MJO, Rossby waves, and mixed Rossby-gravity (MRG) waves (or tropical depression (TD)-type disturbances). From the evolution and structure of these high-frequency waves in relation to that of the MJO and the climate background, the heating and enhanced low-level cyclonic flow in the WNP associated with the MJO and climate background are attributed to the initiation, propagation, and energy dispersion of tropical Rossby and MRG-TD waves, interacting with convection. The relative importance of these large-scale waves to the five TC formations (A-E) is quantified by examining the normalized vorticity at 850 hPa and OLR at the genesis location of each TC. TCs A and C (TCs B and D) were related to the Rossby wave (the MJO), and the MRG-TD was the most related to TC E.

Ching, Lin; Sui, Chung-Hsiung; Yang, Ming-Jen

2010-12-01

250

Communicating the Threat of a Tropical Cyclone to the Eastern Range  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

251

Determination of tropical cyclone surface pressure and winds from satellite microwave data  

NASA Technical Reports Server (NTRS)

An approach to the problem of deducing wind speed and pressure around tropical cyclones is presented. The technique, called the Surface Wind Inference from Microwave data (SWIM technique, uses satellites microwave sounder data to measure upper tropospheric temperature anomalies which may then be related to surface pressure anomalies through the hydrostatic and radiative transfer equations. Surface pressure gradients outside of the radius of maximum wind are estimated for the first time. Future instruments may be able to estimate central pressure with + or - 0/1 kPa accuracy.

Kidder, S. Q.

1979-01-01

252

Statistical Aspects of North Atlantic Basin Tropical Cyclones During the Weather Satellite Era, 1960-2013. Part 2  

NASA Technical Reports Server (NTRS)

This Technical Publication (TP) is part 2 of a two-part study of the North Atlantic basin tropical cyclones that occurred during the weather satellite era, 1960-2013. In particular, this TP examines the inferred statistical relationships between 25 tropical cyclone parameters and 9 specific climate-related factors, including the (1) Oceanic Niño Index (ONI), (2) Southern Oscillation Index (SOI), (3) Atlantic Multidecadal Oscillation (AMO) index, (4) Quasi-Biennial Oscillation (QBO) index, (5) North Atlantic Oscillation (NAO) index of the Climate Prediction Center (CPC), (6) NAO index of the Climate Research Unit (CRU), (7) Armagh surface air temperature (ASAT), (8) Global Land-Ocean Temperature Index (GLOTI), and (9) Mauna Loa carbon dioxide (CO2) (MLCO2) index. Part 1 of this two-part study examined the statistical aspects of the 25 tropical cyclone parameters (e.g., frequencies, peak wind speed (PWS), accumulated cyclone energy (ACE), etc.) and provided the results of statistical testing (i.e., runs-testing, the t-statistic for independent samples, and Poisson distributions). Also, the study gave predictions for the frequencies of the number of tropical cyclones (NTC), number of hurricanes (NH), number of major hurricanes (NMH), and number of United States land-falling hurricanes (NUSLFH) expected for the 2014 season, based on the statistics of the overall interval 1960-2013, the subinterval 1995-2013, and whether the year 2014 would be either an El Niño year (ENY) or a non-El Niño year (NENY).

Wilson, Robert M.

2014-01-01

253

Assimilation of Doppler Weather Radar Data in WRF Model for Simulation of Tropical Cyclone Aila  

NASA Astrophysics Data System (ADS)

For the accurate and effective forecasting of a cyclone, it is critical to have accurate initial structure of the cyclone in numerical models. In this study, Kolkata Doppler weather radar (DWR) data were assimilated for the numerical simulation of a land-falling Tropical Cyclone Aila (2009) in the Bay of Bengal. To study the impact of radar data on very short-range forecasting of a cyclone's path, intensity and precipitation, both reflectivity and radial velocity were assimilated into the weather research and forecasting (WRF) model through the ARPS data assimilation system (ADAS) and cloud analysis procedure. Numerical experiment results indicated that radar data assimilation significantly improved the simulated structure of Cyclone Aila. Strong influences on hydrometeor structures of the initial vortex and precipitation pattern were observed when radar reflectivity data was assimilated, but a relatively small impact was observed on the wind fields at all height levels. The assimilation of radar wind data significantly improved the prediction of divergence/convergence conditions over the cyclone's inner-core area, as well as its wind field in the low-to-middle troposphere (600-900 hPa), but relatively less impact was observed on analyzed moisture field. Maximum surface wind speed produced from DWR-Vr and DWR-ZVr data assimilation experiments were very close to real-time values. The impact of radar data, after final analysis, on minimum sea level pressure was relatively less because the ADAS system does not adjust for pressure due to the lack of pressure observations, and from not using a 3DVAR balance condition that includes pressure. The greatest impact of radar data on forecasting was realized when both reflectivity and wind data (DWR-ZVr and DWR-ZVr00 experiment) were assimilated. It is concluded that after final analysis, the center of the cyclone was relocated very close to the observed position, and simulated cyclone maintained its intensity for a longer duration. Using this analysis, different stages of the cyclone are better captured, and cyclone structure, intensification, direction of movement, speed and location are significantly improved when both radar reflectivity and wind data are assimilated. As compared to other experiments, the maximum reduction in track error was noticed in the DWR-ZVr and DWR-ZVr00 experiments, and the predicted track in these experiments was very close to the observed track. In the DWR-ZVr and DWR-ZVr00 experiments, rainfall pattern and amount of rainfall forecasts were remarkably improved and were similar to the observation over West Bengal, Orissa and Jharkhand; however, the rainfall over Meghalaya and Bangladesh was missed in all the experiments. The influence of radar data reduces beyond a 12-h forecast, due to the dominance of the flow from large-scale, global forecast system models. This study also demonstrates successful coupling of the data assimilation package ADAS with the WRF model for Indian DWR data.

Srivastava, Kuldeep; Bhardwaj, Rashmi

2014-08-01

254

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

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

255

Excitation of equatorial Kelvin and Yanai waves by tropical cyclones in an ocean general circulation model  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TCs) actively contribute to the dynamics of Earth's coupled climate system. They influence oceanic mixing rates, upper-ocean heat content, and air-sea fluxes, with implications for atmosphere and ocean dynamics on multiple spatial and temporal scales. Using an ocean general circulation model with modified surface wind forcing, we explore how TC winds can excite equatorial ocean waves in the tropical Pacific. We highlight a situation where three successive TCs in the western North Pacific region, corresponding to events in 2003, excite a combination of Kelvin and Yanai waves in the equatorial Pacific. The resultant thermocline adjustment significantly modifies the thermal structure of the upper equatorial Pacific and leads to eastward zonal heat transport. Observations of upper-ocean temperature by the Tropical Atmosphere Ocean (TAO) buoy array and sea-level height anomalies using altimetry reveal wave passage during the same time period with similar properties to the modeled wave, although our idealized model methodology disallows precise identification of the TC forcing with the observed waves. Results indicate that direct oceanographic forcing by TCs may be important for understanding the spectrum of equatorial ocean waves, thus remotely influencing tropical mixing and surface energy budgets. Because equatorial Kelvin waves are closely linked to interannual variability in the tropical Pacific, these findings also suggest TC wind forcing may influence the timing and amplitude of El Niño events.

Sriver, R. L.; Huber, M.; Chafik, L.

2012-09-01

256

Excitation of equatorial Kelvin and Yanai waves by tropical cyclones in an ocean general circulation model  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TCs) actively contribute to the dynamics of Earth's coupled climate system. They influence oceanic mixing rates, upper-ocean heat content, and air-sea fluxes, with implications for atmosphere and ocean dynamics on multiple spatial and temporal scales. Using an ocean general circulation model with modified surface wind forcing, we explore how TC winds can excite equatorial ocean waves in the tropical Pacific. We highlight a situation where three successive TCs in the western North Pacific region, corresponding to events in 2003, excite a combination of Kelvin and Yanai waves in the equatorial Pacific. The resultant thermocline adjustment significantly modifies the thermal structure of the upper equatorial Pacific and leads to eastward zonal heat transport. Observations of upper-ocean temperature by the Tropical Atmosphere Ocean (TAO) buoy array and sea-level height anomalies using altimetry reveal wave passage during the same time period with similar properties to the modeled wave, although our idealized model methodology disallows precise identification of the TC forcing with the observed waves. Results indicate that direct oceanographic forcing by TCs may be important for understanding the spectrum of equatorial ocean waves, thus remotely influencing tropical mixing and surface energy budgets. Because equatorial Kelvin waves are closely linked to interannual variability in the tropical Pacific, these findings also suggest TC wind forcing may influence the timing and amplitude of El Niño events.

Sriver, R. L.; Huber, M.; Chafik, L.

2013-01-01

257

Evaluation of official tropical cyclone track forecast over north Indian Ocean issued by India Meteorological Department  

NASA Astrophysics Data System (ADS)

India Meteorological Department (IMD) introduced the objective tropical cyclone (TC) track forecast valid for next 24 hr over the north Indian Ocean (NIO) in 2003. It further extended the validity period up to 72 hr in 2009. Here an attempt is made to evaluate the TC track forecast issued by IMD during 2003-2011 (9 years) by calculating the direct position error (DPE) and skill in track forecast. The accuracy of TC track forecast has been analysed with respect to basin of formation (Bay of Bengal, Arabian Sea and NIO as whole), season of formation (pre-monsoon and post-monsoon seasons), intensity of TCs (cyclonic storm and severe cyclonic storm or higher intensities) and type of track of TCs (climatological/straight moving and recurving/looping type). The average DPE is about 140, 262 and 386 km and skill is about 27%, 39% and 50%, respectively for 24, 48 and 72 hr forecasts over the NIO as a whole during 2009-2011. Though the DPE is higher and skill is less as compared to those in northwest Pacific and north Atlantic Ocean, the rate of decrease (increase) in DPE (skill) is higher over the NIO in recent years. The DPE (skill) over the NIO has decreased (increased) at the rate of about 7.3 km (3%) per year during 2003-2011 for 24 hr forecasts.

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

2013-06-01

258

The evacuation of cairns hospitals due to severe tropical cyclone Yasi.  

PubMed

On February 2, 2011, Tropical Cyclone Yasi, the largest cyclone to cross the Australian coast and a system the size of Hurricane Katrina, threatened the city of Cairns. As a result, the Cairns Base Hospital (CBH) and Cairns Private Hospital (CPH) were both evacuated, the hospitals were closed, and an alternate emergency medical center was established in a sports stadium 15 km from the Cairns central business district. This article describes the events around the evacuation of 356 patients, staff, and relatives to Brisbane (approximately 1,700 km away by road), closure of the hospitals, and the provision of a temporary emergency medical center for 28 hours during the height of the cyclone. Our experience highlights the need for adequate and exercised hospital evacuation plans; the need for clear command and control with identified decision-makers; early decision-making on when to evacuate; having good communication systems with redundancy; ensuring that patients are adequately identified and tracked and have their medications and notes; ensuring adequate staff, medications, and oxygen for holding patients; and planning in detail the alternate medical facility safety and its role, function, and equipment. PMID:22978739

Little, Mark; Stone, Theona; Stone, Richard; Burns, Jan; Reeves, Jim; Cullen, Paul; Humble, Ian; Finn, Emmeline; Aitken, Peter; Elcock, Mark; Gillard, Noel

2012-09-01

259

Relationship between the frequency of tropical cyclones in Taiwan and the Pacific/North American pattern  

NASA Astrophysics Data System (ADS)

The frequency of tropical cyclones (TCs) in Taiwan during June to October (JJASO) is found to have a strong negative correlation with the Pacific/North American (PNA) pattern in the preceding April. In the negative PNA phase, the anomalous cyclonic and the anomalous anticyclonic circulations are intensified at low latitudes and midlatitudes from East Asia to the North Atlantic, respectively, from April to JJASO. Particularly in East Asia, the anomalous southeasterly that converges between the anomalous anticyclone to the east of Japan and the anomalous cyclone to the east of Taiwan plays a decisive role in moving TCs not only to Taiwan, but also to the midlatitude coastal regions of East Asia as a result of the steering flow. In addition, a southwestward extension of a western North Pacific (WNP) high during the positive PNA phase also contributed to a frequent movement of TCs to southern China without traveling north toward the midlatitude regions of East Asia. Due to the difference in the typical tracks of the TC in the WNP according to the PNA phase, the intensity of the TC in the negative PNA phase is stronger than that in the positive PNA phase.

Choi, Ki-Seon; Moon, Il-Ju

260

Ocean feedback on tropical cyclone intensity in a multidecadal coupled simulation of the South Pacific  

NASA Astrophysics Data System (ADS)

Tropical cyclone (TC)-ocean interactions are essential for cyclone formation and evolution. Surface cooling is observed in the cyclone wake and is expected to exert a negative feedback to the storm intensity. Its quantification is assessed with a coupled regional model of the southwest Pacific developed for present climate simulations at mesoscale resolution. The feedback of the ocean response is investigated for the first time by comparing 20-year forced and coupled experiments. This provides statistically robust experiments filling a gap between coarse-resolution and short-term studies. The intensity distribution is significantly affected but the SST feedback is of moderate amplitude (5-15 hPa/Celsius) compared with theoretical models. Our analysis contradicts the direct thermodynamic control of TC intensification by surface moisture fluxes in favor of a storm-scale dynamic control. In addition, regional oceanography strongly modulates TC-ocean coupling. It is stronger in the Coral Sea that has shallow mixed layer and numerous eddies but extremely weak in the warm pool that has deep mixed layer, thick barrier layer and no mesoscale activity. These pre-conditions to SST cooling impact the TC distribution.

Jullien, Swen; Marchesiello, Patrick; Menkes, Christophe; Lefevre, Jérôme; Jourdain, Nicolas; Lengaigne, Matthieu; Samson, Guillaume

2014-05-01

261

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

262

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.

263

The Relationship of Tropical Cyclone Convective Intensity to Passive Microwave Observations  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

264

Tropical cyclones cause CaCO3 undersaturation of coral reef seawater in a high-CO2 world  

NASA Astrophysics Data System (ADS)

Ocean acidification is the global decline in seawater pH and calcium carbonate (CaCO3) saturation state (?) due to the uptake of anthropogenic CO2 by the world's oceans. Acidification impairs CaCO3 shell and skeleton construction by marine organisms. Coral reefs are particularly vulnerable, as they are constructed by the CaCO3 skeletons of corals and other calcifiers. We understand relatively little about how coral reefs will respond to ocean acidification in combination with other disturbances, such as tropical cyclones. Seawater carbonate chemistry data collected from two reefs in the Florida Keys before, during, and after Tropical Storm Isaac provide the most thorough data to-date on how tropical cyclones affect the seawater CO2 system of coral reefs. Tropical Storm Isaac caused both an immediate and prolonged decline in seawater pH. Aragonite saturation state was depressed by 1.0 for a full week after the storm impact. Based on current "business-as-usual" CO2 emissions scenarios, we show that tropical cyclones with high rainfall and runoff can cause periods of undersaturation (? < 1.0) for high-Mg calcite and aragonite mineral phases at acidification levels before the end of this century. Week-long periods of undersaturation occur for 18 mol % high-Mg calcite after storms by the end of the century. In a high-CO2 world, CaCO3 undersaturation of coral reef seawater will occur as a result of even modest tropical cyclones. The expected increase in the strength, frequency, and rainfall of the most severe tropical cyclones with climate change in combination with ocean acidification will negatively impact the structural persistence of coral reefs.

Manzello, Derek; Enochs, Ian; Musielewicz, Sylvia; Carlton, Renée.; Gledhill, Dwight

2013-10-01

265

Tropical Cyclones Cause CaCO3 Undersaturation of Coral Reef Seawater in a High-CO2 World  

NASA Astrophysics Data System (ADS)

Ocean acidification is the global decline in seawater pH and calcium carbonate (CaCO3) saturation state (?) due to the uptake of anthropogenic CO2 by the world's oceans. Acidification impairs CaCO3 shell and skeleton construction by marine organisms. Coral reefs are particularly vulnerable, as they are constructed by the CaCO3 skeletons of corals and other calcifiers. We understand relatively little about how coral reefs will respond to ocean acidification in combination with other disturbances, such as tropical cyclones. Seawater carbonate chemistry data collected from two reefs in the Florida Keys before, during, and after Tropical Storm Isaac provide the most thorough data to-date on how tropical cyclones affect the seawater CO2-system of coral reefs. Tropical Storm Isaac caused both an immediate and prolonged decline in seawater pH. Aragonite saturation state was depressed by 1.0 for a full week after the storm impact. Based on current 'business-as-usual' CO2 emissions scenarios, we show that tropical cyclones with high rainfall and runoff can cause periods of undersaturation (? < 1.0) for high-Mg calcite and aragonite mineral phases at acidification levels before the end of this century. Week-long periods of undersaturation occur for 18 mol% high-Mg calcite after storms by the end of the century. In a high-CO2 world, CaCO3 undersaturation of coral reef seawater can occur as a result of even modest tropical cyclones. The expected increase in the strength, frequency, and rainfall of the most severe tropical cyclones with climate change in combination with ocean acidification will negatively impact the structural persistence of coral reefs over this century.

Manzello, D.; Enochs, I.; Carlton, R.; Musielewicz, S.; Gledhill, D. K.

2013-12-01

266

Restratification of the upper ocean after the passage of a tropical cyclone  

NASA Astrophysics Data System (ADS)

Strong winds associated with tropical cyclones can pump heat downward by stirring the surface warm water with the cooler water beneath, resulting in a cooling in the surface mixed layer and a warming in the subsurface layer (i.e., the upper thermocline). Previous studies addressing the decay of the cold wake and the impact of tropical cyclones on meridional heat transport assume that the cold wake is completely removed by anomalous air-sea heat fluxes within several weeks while the subsurface warming can persist much longer, leading to a net heat gain in the upper ocean, which may further influence the meridional heat transport. Besides air-sea heat fluxes, however, vertical and horizontal heat fluxes associated with dynamical processes in the upper ocean, such as baroclinic instability and large-scale horizontal advection, can also contribute to the recovery and restratification of the upper ocean. Here we use satellite sea surface temperature (SST) data and numerical simulations to investigate the restratification process of the upper ocean after the passage of a tropical cyclone with an emphasis on the role of baroclinic instability. Composite analysis based on satellite observations shows that the cyclone-induced cold wake decays with an e-folding time of 1-2 weeks independent of the strength of the cyclone and of the magnitude of the wake. A high-resolution three-dimensional simulation that includes the process of baroclinic instability well reproduces this decay rate. Also, the simulated upper-ocean restratification resembles the published in-situ observations after the passage of Hurricane Fabian in 2003. The model ocean is restratified after approximately one month with a net heat gain in the water column due to anomalous air-sea heat fluxes. The model shows however that vertical heat fluxes associated with baroclinic instability dominate over air-sea heat fluxes in restoring the climatological mixed layer (CML) heat content during the first month. Such dynamical heat fluxes are in association with cold filaments and rings with a spatial scale of several kilometers, and account for approximately 30% of the full recovery of the CML heat content. Comparison with two-dimensional simulations that exclude baroclinic adjustment further highlights the importance of baroclinic instability: it can not only input a considerable amount of heat into the CML, but establish strong stratification there, inhibiting the downward penetration of heat contributed by diabatic heating at the surface; both effects help fasten the recovery of surface water temperatures. These results indicate that the effect of those submesoscale features must be parameterized in a climate model in order to fully capture the impact of tropical cyclones on the upper-ocean heat content and the Earth's climate. Additional experiments show that the influence of changes in Newtonian cooling rate and post-storm wind strength on the contribution of baroclinic instability to the recovery of the CML heat content is modest, though they can significantly affect the recovery of SST and of the total CML heat content. Further discussion of the role of large-scale horizontal heat advection in the restratification process will also be presented.

Mei, W.; Pasquero, C.

2010-12-01

267

Global Tropical Moisture Exports and their Influence on Extratropical Cyclone Activity  

NASA Astrophysics Data System (ADS)

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.

Knippertz, P.; Wernli, H.; Gläser, G.

2012-04-01

268

Impact of Aerosols on Tropical Cyclones: An Investigation Using Convection-permitting Model Simulation  

SciTech Connect

The role of aerosols effect on two tropical cyclones over Bay of Bengal are investigated using a convection permitting model with two-moment mixed-phase bulk cloud microphysics scheme. The simulation results show the role of aerosol on the microphysical and dynamical properties of cloud and bring out the change in efficiency of the clouds in producing precipitation. The tracks of the TCs are hardly affected by the changing aerosol types, but the intensity exhibits significant sensitivity due to the change in aerosol contribution. 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 the 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 other two perturbations of aerosol. All these studies show the robustness of the concept of TC weakening by storm ingestion of high concentrations of CCN. The consistency of these model results gives us confidence in stating 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 sub-continent, this study suggests pollution may be weakening TCs over the Bay of Bengal.

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

2013-07-16

269

Suppression of Powerful Clouds and Prevention of D Estructive Tropical and Extratropical Cyclones, S Evere Thunderstorms, Tornadoes, and Catastrophic Floods  

NASA Astrophysics Data System (ADS)

Destructive tropical storms, hurricanes (typhoons), tornadoes, severe thunderstorms, and extratropical cyclones and storms resulted in catastrophic floods annually inflict multitudinous death and injury and bring huge material damage in many countries. This problem is highly important and to date has not been solved. At the same time, practically all researches made concerning these phenomena fail to take into account that the origin and intensification of tropical cyclones, hurricanes, and tornadoes take place under conditions of an abnormally strong electric field which together with electromagnetohydrodynamic interaction occupies a key position in the ntensification process. The detailed description of the electromagnetohydrodynamic model explaining the processes of energy conversion in tropical cyclones, hurricanes, and tornadoes is presented. Herewith, tropical cyclones and storms, hurricanes, powerful thunderclouds generating tornadoes, destructive extratropical cyclones resulting in catastrophic floods are the powerful cloud systems containing huge mass of water. According to a hypothesis proposed in the paper an electric field coupled with powerful clouds and electric forces play a cardinal role in supporting of this huge mass of water at a high altitude in the troposphere and in stability of powerful clouds sometimes during rather long-duration time. On the basis of the hypothesis a highly effective method of volume electric charge neutralization of powerful clouds is proposed. It results in the decrease of an electric field, a sudden increase of precipitation, and subsequent degradation of powerful clouds. This method based on the natural phenomenon ensures prevention of intensification of tropical and extratropical cyclones and their transition to the storm and hurricane (typhoon) stages, which makes it possible to avoid catastrophic floods. It ensures as well suppression of severe thunderclouds, which, in turn, eliminates development of dangerous thunderstorms and the possibility of emergence and intensification of tornadoes.

Krasilnikov, E.

270

Objective Operational Utilization of Satellite Microwave Scatterometer Observations of Tropical Cyclones  

NASA Technical Reports Server (NTRS)

This study has demonstrated that high-resolution scatterometer measurements in tropical cyclones and other high-marine surface wind regimes may be retrieved accurately for wind speeds up to about 35 mls (1-hour average at 10 m) when the scatterometer data are processed through a revised geophysical model function, and a spatial adaptive algorithm is applied which utilizes the fact that wind direction is so tightly constrained in tile inner core of severe marine storms that wind direction may be prescribed from conventional data. This potential is demonstrated through case studies with NSCAT data in a severe West Pacific Typhoon (Violet, 1996) and an intense North Atlantic hurricane (Lili, 1996). However, operational scatterometer winds from NSCAT and QuickScat in hurricanes and severe winter storms are biased low in winds above 25 m/s. We have developed an inverse model to specify the entire surface wind field about a tropical cyclone from operational QuickScat scatterometer measurements within 150 nm of a storm center with the restriction that only wind speeds up to 20 m/s are used until improved model function are introduced. The inverse model is used to specify the wind field over the entire life-cycle of Hurricane Floyd (1999) for use to drive an ocean wave model. The wind field compares very favorably with wind fields developed from the copious aircraft flight level winds obtained in this storm.

Cardone, Vincent J.; Cox, Andrew T.

2000-01-01

271

Mechanisms for Secondary Eyewall Formation in Tropical Cyclones: A Case Study of Hurricane Katrina (2005)  

NASA Astrophysics Data System (ADS)

The Weather Research and Forecast (WRF) model is used to simulate the last eyewall replacement cycle (ERC) of Hurricane Katrina (2005) just before it's landfall in the Louisiana coastline. In this study, we pursue a complete understanding of the physics behind the secondary eyewall formation (SEF) in tropical cyclones. The simulation results show the occurrence of the early stages of an ERC in the simulated storm just before landfall. This confirms that with the appropriate set of physics parameterization schemes, grid spacing and initial conditions, the numerical model is able to reproduce ERCs on certain tropical cyclones with no data assimilation or extra data inputs. Strong updrafts are observed to converge in a ring outside the primary eyewall of Hurricane Katrina (2005) suggesting SEF during that period. The increase of divergence outside the primary eyewall with an outer-ring of convergence forming above the boundary layer can be part of the mechanisms that lead to SEF. Also, potential vorticity (PV) field is analyzed for its possible relationship with the development of the secondary eyewall. This detailed study of the pre-ERC events in the inner-core of Hurricane Katrina can build the foundations for testing some of the existing hypotheses for the development of secondary eyewalls leading to new ideas behind their formation.

Garcia-Rivera, J. M.; Lin, Y.

2013-05-01

272

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

NASA Technical Reports Server (NTRS)

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.

Wilson, Robert M.

2010-01-01

273

Modeling High-Impact Weather and Climate: Lessons From a Tropical Cyclone Perspective  

SciTech Connect

Although the societal impact of a weather event increases with the rarity of the event, our current ability to assess extreme events and their impacts is limited by not only rarity but also by current model fidelity and a lack of understanding of the underlying physical processes. This challenge is driving fresh approaches to assess high-impact weather and climate. Recent lessons learned in modeling high-impact weather and climate are presented using the case of tropical cyclones as an illustrative example. Through examples using the Nested Regional Climate Model to dynamically downscale large-scale climate data the need to treat bias in the driving data is illustrated. Domain size, location, and resolution are also shown to be critical and should be guided by the need to: include relevant regional climate physical processes; resolve key impact parameters; and to accurately simulate the response to changes in external forcing. The notion of sufficient model resolution is introduced together with the added value in combining dynamical and statistical assessments to fill out the parent distribution of high-impact parameters. Finally, through the example of a tropical cyclone damage index, direct impact assessments are presented as powerful tools that distill complex datasets into concise statements on likely impact, and as highly effective communication devices. Capsule: "Combining dynamical modeling of high-impact weather using traditional regional climate models with statistical techniques allows for comprehensive sampling of the full distribution, uncertainty estimation, direct assessment of impacts, and increased confidence in future changes."

Done, James; Holland, Greg; Bruyere, Cindy; Leung, Lai-Yung R.; Suzuki-Parker, Asuka

2012-06-01

274

Oscillation responses to tropical Cyclone Gonu in northern Arabian Sea from a moored observing system  

NASA Astrophysics Data System (ADS)

In June 2007, tropical Cyclone Gonu passed over an ocean observing system consisting of a deep autonomous mooring system in the northern Arabian Sea and a shallow cabled mooring system in the Sea of Oman. Gonu was the largest cyclone known to have occurred in the Arabian Sea and to strike the Arabian Peninsula. The instruments on the moorings continuously recorded water velocities, temperature, conductivity, pressure, dissolved oxygen (DO) and turbidity at multiple depths and at hourly intervals during the storm. Near-inertial oscillations at all moorings from thermocline to seafloor are coincident with the arrival of Gonu. Sub-inertial oscillations with periods of 2-10 day are recorded at the post-storm relaxation stage of Gonu, primarily in the thermocline of the deep array and at the onshore regions of the shallow array. These oscillations consist of warm, saline water masses, likely originating from the Persian Gulf. Prominent 12.7-day sub-inertial waves, measured at a station ?300 km offshore, are bottom-intensified and have characteristics of baroclinic topographically trapped waves. Theoretical results from a topographically trapped wave model are in a good agreement with the observed 12.7-day waves at Murray Ridge. The wavelength of the 12.7-day waves is about 590 km calculated from the dispersion relationship. Further analysis suggests that a resonant standing wave is responsible for trapping the 12.7-day wave energy inside the Sea of Oman basin. The observational results reported here are the first measurements of deepwater responses to a tropical cyclone in the Sea of Oman/Arabian Sea. Our study demonstrates the utility of sustained monitoring for studying the impact of extreme weather events on the ocean.

Wang, Zhankun; DiMarco, Steven F.; Stössel, Marion M.; Zhang, Xiaoqian; Howard, Matthew K.; du Vall, Ken

2012-06-01

275

The Air-Sea Interface and Surface Stress under Tropical Cyclones  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

276

Influence of local and remote SST on North Atlantic tropical cyclone potential intensity  

NASA Astrophysics Data System (ADS)

We examine the role of local and remote sea surface temperature (SST) on the tropical cyclone potential intensity in the North Atlantic using a suite of model simulations, while separating the impact of anthropogenic (external) forcing and the internal influence of Atlantic Multidecadal Variability. To enable the separation by SST region of influence we use an ensemble of global atmospheric climate model simulations forced with historical, 1856-2006 full global SSTs, and compare the results to two other simulations with historical SSTs confined to the tropical Atlantic and to the tropical Indian Ocean and Pacific. The effects of anthropogenic plus other external forcing and that of internal variability are separated by using a linear, "signal-to-noise" maximizing EOF analysis and by projecting the three model ensemble outputs onto the respective external forcing and internal variability time series. Consistent with previous results indicating a tampering influence of global tropical warming on the Atlantic hurricane potential intensity, our results show that non-local SST tends to reduce potential intensity associated with locally forced warming through changing the upper level atmospheric temperatures. Our results further indicate that the late twentieth Century increase in North Atlantic potential intensity, may not have been dominated by anthropogenic influence but rather by internal variability.

Camargo, Suzana J.; Ting, Mingfang; Kushnir, Yochanan

2013-03-01

277

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

NASA Astrophysics Data System (ADS)

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.

Abdullah, Warith; Reddy, Remata

278

Evolution of the Surface Wind Field in an Intensifying Tropical Cyclone.  

NASA Astrophysics Data System (ADS)

The surface wind field in a developing tropical cyclone (Agnes, 1972) was analyzed over a 1660 km radius for four days using conventional surface data, as the storm evolved from a disorganized depression to a hurricane. The transition to hurricane intensity was characterized by a wavelike disturbance propagating inward at 15 m s1 from the outermost radii to the storm core over a 36-hour period. This propagating disturbance was clearly visible in the radial and vertical motion fields as a surge of inflow and upward motion. Rapid intensification of the storm began within hours after the leading edge of the surge reached the storm center. The analysis of consecutive 12-hour periods without compositing of data from nonsynoptic times was essential for identification of this feature.The surge had the same asymmetry as the upper-level outflow channel, indicating the possible involvement of the outflow layer in its initiation. No clear evidence of an external forcing mechanism for the surge, such as the passage of an easterly wave across the circulation, could be found. No instability theory could account for propagation of this feature across regions with such strongly varying dynamical properties. As a result, it remains uncertain whether the inflow surge represented an environmental trigger to hurricane formation or a manifestation of an internal instability.The boundary layer momentum budget was dominated by Coriolis torque and frictional dissipation. The sum of these two terms acted as a momentum source primarily during the passage of the inflow surge across each radial region. Inward lateral flux of momentum contributed significantly only within 440 km of the center.A distinct diurnal oscillation in pressure tendency occurred until hurricane strength was reached, with maximum deepening at 1200 local time, and minimum deepening at 0000 local time. Diurnal oscillations in other variables were more subtle and often at variance with those described in other tropical cyclones.Because the inflow surge developed at outer radii 36 hours prior to rapid deepening and had a clear signature in the time change of radial mass flux, it provides a potential tool for forecasting tropical cyclogenesis 24 hours or more in advance which requires only the use of conventional data. More study is needed to determine whether such an early warning signal frequently occurs in intensifying tropical cyclones.

Molinari, John; Skubis, Steven

1985-12-01

279

Possible Linkage between Monsoon Trough Variability and Tropical Cyclone Activity over Western North Pacific: Role of Tropical Waves  

NASA Astrophysics Data System (ADS)

The present study investigates the influence of the monsoon trough (MT) on the interannual variability of tropical cyclone (TC) activity over the western North Pacific during July-November for the period 1979-2007. It is shown that the TC activity is closely related to the MT location. During the years when the MT extends eastward (retreats westward), more (less) TCs form within the southeastern quadrant of the western North Pacific. Such a relationship can be explained by the changes in tropical waves, such as mixed Rossby-gravity (MRG) waves and (tropical depression) TD-type disturbances, associated with the movement of the MT. An eastward extension of the MT coincides with enhanced TD-MRG type disturbances and a clear MRG-to-TD transition over the southeast quadrant of the western North Pacific. Such a transition is unclear during the years when the MT retreats westward. These waves associated with the eastern extension of the MT are favorable for TC genesis, while those associated with the westward retreat of the MT are not. Diagnosis of the barotropic energy conversion indicates that both the rotational and divergent components of the background flow change associated with MT are responsible for energy conversion from the mean flow to the TD-MRG perturbations. This is an important reason for the linkage between MT variability and TC genesis over the western North Pacific.

Wu, Liang; Huang, Ronghui; Wen, Zhiping

2014-05-01

280

Evaluation of the productivity decrease risk due to a future increase in tropical cyclone intensity in Japan.  

PubMed

A number of scientists have recently conducted research that shows that tropical cyclone intensity is likely to increase in the future. This would result in an increase in the damage along with a decrease in economic productivity due to precautionary cessation of the economic activity of the affected areas during the passage of the cyclone. The economic effect of this stop in economic activity is a phenomenon that has not received much attention in the past, and the cumulative effect that it can have on the Japanese economy over the next 75 years has never been evaluated. The starting point for the evaluation of the economic risks is the change in the patterns of tropical cyclone intensity suggested by Knutson and Tuleya. The results obtained show how a significant decrease in the overall productivity of the country could be expected, which could lower GDP by between 6% and 13% by 2085. PMID:20807379

Esteban, Miguel; Longarte-Galnares, Gorka

2010-12-01

281

The Influence of El Nin~oSouthern Oscillation and the Atlantic Multidecadal Oscillation on Caribbean Tropical Cyclone Activity  

E-print Network

The Influence of El Nin~o­Southern Oscillation and the Atlantic Multidecadal Oscillation, the Atlantic multidecadal oscillation is shown to play a significant role in Caribbean hurricane activity~o years in a negative Atlantic multidecadal oscillation period. 1. Introduction Tropical cyclones

Gray, William

282

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

E-print Network

in oceanic stratification rather than to differences in TC wind energy input. During the postmonsoon season that TCs primarily draw their energy from evaporation at the ocean surface [Riehl, 1950]. TCs generallyInfluence of upper-ocean stratification on tropical cyclone-induced surface cooling in the Bay

283

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

Microsoft Academic Search

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

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

2010-01-01

284

Impact of global warming on tropical cyclone genesis in coupled and forced simulations: role of SST spatial anomalies  

Microsoft Academic Search

The response of tropical cyclones (TC) activity to global warming has not yet reached a clear consensus in the Fourth Assessment Report (AR4) published by the Intergovernmental Panel on Climate Change (IPCC, 2007) or in the recent scientific literature. Observed series are neither long nor reliable enough for a statistically significant detection and attribution of past TC trends, and coupled

Jean-François Royer; Fabrice Chauvin; Anne-Sophie Daloz

2010-01-01

285

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

E-print Network

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

Gray, William

286

PUBLISHED ONLINE: 12 FEBRUARY 2012 | DOI: 10.1038/NCLIMATE1410 Global trends in tropical cyclone risk  

E-print Network

, levels of poverty and governance. Despite the projected reduction in the frequency of tropical cyclones coastal flooding. Between 1970 and 2009, singular TC events inflicted the highest death toll (Bhola extensively from one event to another. Understanding the probability of losses requires an identification

Kossin, James P.

287

Global Tropical Cyclone Winds from the QuikSCAT and OceanSAT-2 Scatterometers  

NASA Astrophysics Data System (ADS)

We have produced a comprehensive set of tropical cyclone storm wind retrieval scenes for all ten years of QuikSCAT data and one year of OceanSAT-2 data. The wind speeds were corrected for rain and optimized to avoid saturation at high winds using an artificial neural network method similar to that in [1] and [2]. The QuikSCAT wind imagery and the quantitative speed, direction, and backscatter data can be obtained at http://tropicalcyclone.jpl.nasa.gov. The QuikSCAT wind speeds have been validated against best track intensity (i.e., maximum wind speeds), H*WIND tropical cyclone wind model analysis fields, and wind speeds from aircraft overflights (GPS drop wind sondes and step frequency microwave radiometer (SFMR) wind measurements). Storms from all basins are included for a total of 21600 scenes over the ten years of nominal QuikSCAT operations. Of these, 11435 scenes include the best track center of the cyclone in the retrieved wind field. Among these, 3295 were of tropical storms and 788, 367, 330, 289, and 55 were of category 1, 2, 3, 4 and 5 hurricanes, respectively, on the Saffir-Simpson Hurricane Wind Scale. In addition to the QuikSCAT hurricane winds, we have also processed one year of wind fields from the Indian Space Research organization (ISRO) OceanSAT-2 satellite. OceanSAT-2 employs a scanning pencil beam Ku-band scatterometer with a design similar to QuikSCAT. JPL and NOAA have been working extensively with ISRO to aid in cross calibration between OceanSAT-2 and QuikSCAT. Toward this end the QuikSCAT instrument has been repointed in order to acquire data at the OceanSAT-2 incidence angles, and several meetings in India between the teams have taken place. The neural network that was trained on QuikSCAT data was used to retrieve OceanSAT-2 winds. The backscatter inputs to the network were transformed to match the histograms of the corresponding values in the QuikSCAT data set. We examine the scatterometer winds to investigate the relationship between asymmetry in the wind fields and cyclone intensity. In particular, we estimate the typical storm relative wind speed distribution as a function of storm intensity, intensification (max wind speed change), and geographical location. The goal of this investigation is to determine whether or not asymmetry in the speed distribution correlates with storm intensification. References: [1] B. W. Stiles and R.S. Dunbar, "A Neural Network Technique For Improving The Accuracy Of Scatterometer Winds In Rainy Conditions." IEEE TGARS, Vol 48 , No. 8, P 3114-3122, August 2010. [2] B. W Stiles, S. Hristova-Veleva, et al, "Obtaining Accurate Ocean Surface Winds In Hurricane Conditions: A Dual Frequency Scatterometry Approach," IEEE TGARS, Vol 48 , No. 8, P 3101-3113, August 2010. Acknowledgement: The work reported here was performed at the Jet Propulsion Laboratory, California Institute of Technology, and at the National Hurricane Center under contract with the National Aeronautics and Space Administration. We would like to thank the Indian Space Research Organization for providing the OceanSAT-2 scatterometer data that we used to determine tropical cyclone winds.

Stiles, B. W.; Danielson, R. E.; Poulsen, W. L.; Fore, A.; Brennan, M. J.; Shen, T. J.; Hristova-Veleva, S. M.

2012-12-01

288

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

NASA Astrophysics Data System (ADS)

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.

Antinao, J.; Farfan, L.

2012-12-01

289

Seasonal tropical cyclone precipitation in Texas: A statistical modeling approach based on a 60 year climatology  

NASA Astrophysics Data System (ADS)

Sixty years of tropical cyclone precipitation (TCP) in Texas has been analyzed because of its importance in extreme hydrologic events and the hydrologic budget. We developed multiple linear regression models to provide seasonal forecasts for annual TCP, TCP's contribution (percentage) to total precipitation, and the number of TCP days in Texas. The regression models are based on three or fewer predictors with model fits ranging from 0.18 to 0.43 (R2) and cross-validation accuracy of 0.05-0.36 (R2). La Niña exhibits the most important control on TCP in Texas. It is the major driver in our models and acts to reduce the vertical shear in the Caribbean and the tropical Atlantic, thereby generating more precipitating storms in Texas. Lower maximum potential velocity, the theoretical maximum wind speed that storms can attain, in the Gulf of Mexico, and low-level vorticity in the Atlantic hurricane main development region increased the modeled R2 by 20% or more. Both variables have negative coefficients in the TCP models. Lower maximum potential velocity and vorticity are associated with tropical cyclones with lower maximum wind speed and slower translation speed. Such weak TCs produce the majority of TCP and extreme TCP events in Texas. The quartiles of the TCs with strongest maximum wind speed and fastest translation speed are not associated with the largest mean daily precipitation based on observations in Texas. We have also shown that sea level pressure in the Gulf of Mexico, sea surface temperature in the Caribbean, and the North Atlantic Oscillation are potentially important predictors of seasonal TCP in Texas.

Zhu, Laiyin; Frauenfeld, Oliver W.; Quiring, Steven M.

2013-08-01

290

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

291

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

292

Forecasting the Probability of Tropical Cyclone Formation: the reliability of NOAA forecasts from the 2012 hurricane season  

NASA Astrophysics Data System (ADS)

Atlantic tropical cyclones are responsible for some of the world's greatest economic losses due to natural hazards. Short-term (48 hour) probabilistic forecasting has become an integral part of the prediction of these events. Forecasters from the National Oceanic and Atmospheric Administration's (NOAA) National Hurricane Center (NHC) post subjective probability tropical cyclone forecasts out to 48 hours during each hurricane season. Reliability diagrams provide an immediate indication of the quality of a probabilistic forecasting system by illustrating the degree of correspondence between the observed frequencies of an event and the forecast probabilities assigned to it. In their most common format, however, reliability diagrams fail to provide a truly representative measure of reliability, as they do not clearly indicate the variability expected even in a perfectly reliable forecast system. A revised format (J. Broecker and L. A. Smith, Weather and Forecasting, 22(3), pp651-661, 2007) aids the visual evaluation of the likelihood of the observed relative frequencies of tropical cyclones during the 2012 hurricane season. This is done by indicating the variability expected under the assumption that the NHC's probability forecasts were genuinely reliable. The strengths and weaknesses of the 2012 forecasts are examined. For most categories, the forecast probabilities are consistent with the observed frequencies of tropical cyclones. The verisimilitude of forecasts of very high probability and very low probability (including forecasts of "zero" probability) are discussed. In addition, relationships between "time until event" and forecast probability are analysed. In 2012, forecasts of a probability of 70% or more were each followed by events (52 out of 52). It is interesting to note the distribution of time of onset of these events within the 48 hour window. It is hoped that these observations may suggest ways to improve the utility and evaluation of operational tropical cyclone forecasts.

Jarman, Alex; Smith, Leonard

2013-04-01

293

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

SciTech Connect

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.

Lackmann, Gary

2013-06-10

294

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

NASA Astrophysics Data System (ADS)

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

Scott, C. A.; Farfan, L.

2012-12-01

295

Change of tropical cyclone activity by Pacific-Japan teleconnection pattern in the western North Pacific  

NASA Astrophysics Data System (ADS)

This study shows that the Pacific-Japan (PJ) teleconnection pattern has a significant influence on tropical cyclone (TC) activities over the western North Pacific (WNP) during the boreal summer (July, August, and September). During positive (negative) PJ phase, TCs form at a more northward (southward) location, recurve at a more northeastward (southwestward) location, and frequently pass over the northeast Asian (southeast Asian) region, including Korea and Japan (South China Sea and southern China). In particular, this difference in the TC track between the two phases is observed as a dipole-like pattern between the regions of Southeast and Northeast Asia. The TC characteristics during the positive PJ phase are caused by the following two stronger atmospheric circulations over the WNP: an anticyclonic circulation centered to the east of Japan and a cyclonic circulation centered to the east of Taiwan. The southeasterly between these two circulations serves as steering flow that TCs move northward toward Korea and Japan from the northeast of the Philippines. Conversely, TCs during the negative PJ phase mainly move westward toward the South China Sea and southern China by the easterly from a stronger anticyclonic circulation centered to the east of Taiwan. As a result of this feature of TC track during the negative PJ phase, TC lifetime is shorter and TC intensity is weaker.

Choi, Ki-Seon; Wu, Chun-Chieh; Cha, Eun-Jeong

2010-10-01

296

Predictability and prediction of tropical cyclones on daily to interannual time scales  

NASA Astrophysics Data System (ADS)

The spatial and temporal complexity of tropical cyclones (TCs) raises a number of scientific questions regarding their genesis, movement, intensification, and variability. In this dissertation, the principal goal is to determine the current state of predictability for each of these processes using global numerical prediction systems. The predictability findings are then used in conjunction with several new statistical calibration techniques to develop a proof-of-concept, operational forecast system for North Atlantic TCs on daily to intraseasonal time scales. To quantify the current extent of tropical cyclone predictability, we assess probabilistic forecasts from the most advanced global numerical weather prediction system to date, the ECMWF Variable Resolution Ensemble Prediction System (VarEPS; Hamill et al. 2008, Hagedorn et al. 2012). Using a new false alarm clustering technique to maximize the utility of the VarEPS, the ensemble system is shown to provide well-calibrated probabilistic forecasts for TC genesis through a lead-time of one week and pregenesis track forecasts with similar skill compared to the VarEPS's postgenesis track forecasts. These findings provide evidence that skillful real-time TC genesis predictions may be made in the North Indian Ocean—a region that even today has limited forecast warning windows for TCs relative to other ocean basins. To quantify the predictability of TCs on intraseasonal time scales, forecasts from the ECMWF Monthly Forecast System (ECMFS) are examined for the North Atlantic Ocean. From this assessment, dynamically based forecasts from the ECMFS provide forecast skill exceeding climatology out to weeks three and four for portions of the southern Gulf of Mexico, western Caribbean and the Main Development Region. Forecast skill in these regions is traced to the model's ability to capture correctly the variability in deep-layer vertical wind shear as well as the relative frequency of easterly waves moving through these regions. Following the TC predictability studies, a proof-of-concept operational forecast system for North Atlantic TCs is presented for daily to intraseasonal time scales. Findings from the predictability studies are used in conjunction with recently developed forecast calibration techniques to render the VarEPS and ECMFS forecasts more useful in an operational setting. The proposed combination of bias-calibrated regional probabilistic forecast guidance along with objectively-defined measures of confidence is a new way of providing TC forecasts on intraseasonal time scales. On interannual time scales, the predictability of TCs is examined by considering their relationship with tropical Atlantic easterly waves. First, a set of easterly wave climatologies for the Climate Forecast System-Reanalysis, ERA-Interim, ERA-40, and NCEP/NCAR Reanalysis are developed using a new easterly wave tracking algorithm based on 700 hPa curvature relative vorticity anomalies. From the reanalysis-derived easterly wave climatologies, a moderately positive and statistically significant relationship is seen with tropical Atlantic TCs, suggesting that approximately 20-30% of the total variance in the number of TCs on interannual time scales may be explained by the frequency of easterly waves. In relation to large-scale climate modes, the Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Mode (AMM) exhibit the strongest positive covariability with Atlantic easterly wave frequency. Besides changes in the number of easterly waves, the intensification efficiency of easterly waves, which is the percentage of waves that induce North Atlantic TC formation, has also been evaluated. These findings offer a plausible physical explanation for the recent increase in the number of NATL TCs, as it has been concomitant with an increasing trend in both the number of tropical Atlantic easterly waves and intensification efficiency. In addition, the easterly wave-tropical cyclone pathway is likely an important mechanism governing how the AMO and AMM modulate North Atlantic TC frequency—more

Belanger, James Ian

297

Modeled dependence of wind and waves on ocean temperature in tropical cyclones  

NASA Astrophysics Data System (ADS)

A coupled ocean-atmosphere-wave model is used to investigate the sensitivity of surface wind speed and significant wave height to ocean temperature for idealized tropical cyclones (TCs). More intense and larger TCs, with higher waves, form when ocean temperature is increased. The maximum significant wave height increases more than the maximum wind speed for TCs up to hurricane force wind. However, above hurricane force wind the change in maximum wind speed is similar or greater than the change in maximum significant wave height. This can be explained by the wind drag coefficient decreasing as wind speed exceeds hurricane force wind, so that the growth of waves is dampened. The areal footprint of wave height grows considerably more than the maximum as ocean temperature is increased. This suggests a large increase in the surface area of damaging waves generated by TCs may be the dominant impact of a future warmer ocean.

Phibbs, Samuel; Toumi, Ralf

2014-10-01

298

Impacts of the diurnal cycle of radiation on tropical cyclone intensification and structure  

NASA Astrophysics Data System (ADS)

To investigate the impacts of the diurnal cycle on tropical cyclones (TCs), a set of idealized simulations were conducted by specifying different radiation (i.e., nighttime-only, daytime-only, full diurnal cycle). It was found that, for an initially weak storm, it developed faster during nighttime than daytime. The impacts of radiation were not only on TC intensification, but also on TC structure and size. The nighttime storm tended to have a larger size than its daytime counterparts. During nighttime, the radiative cooling steepened the lapse rate and thus reduced the static stability in cloudy regions, enhancing convection. Diabatic heating associated with outer convection induced boundary layer inflows, which led to outward expansion of tangential winds and thus increased the storm size.

Ge, Xuyang; Ma, Yue; Zhou, Shunwu; Li, Tim

2014-11-01

299

Conceptual design of a tropical cyclone UAV based on the AR-6 Endeavor aircraft  

E-print Network

This paper reports on the preliminary simulation work for a 1-meter class tropical cyclone UAV (unmanned aerial vehicle) based on the Formula-One AR-6 Endeavor full-sized airplane. Variants with different wing span are evaluated using the popular RealFlight radio-control simulator. The 84 cm wing-span platform achieves a maximum cruising speed (Vh) of 407 kmh-1 and demonstrates responsive flight controls throughout its flight envelope even in sustained wind speed of 225 kmh-1. Being a small and agile UAV, it can be flown below the storm to measure surface wind directly and avoid possible uncertainty associated with the vertical wind profile adjustment. Chute-free vertical retardation technique is also proposed. The ultimate aim of the research is to develop cost effective UAVs that can be employed in a multi-agent setting to acquire high resolution data to enhance understanding of cyclogenesis and to make better predictions.

Poh, Chung-Kiak; Yeh, Mei-Ling; Chou, Tien-Yin

2014-01-01

300

Increase in the intensity of postmonsoon Bay of Bengal tropical cyclones  

NASA Astrophysics Data System (ADS)

The postmonsoon (October-November) tropical cyclone (TC) season in the Bay of Bengal (BoB) has spawned many of the deadliest storms in recorded history. Here it is shown that the intensity of major TCs (wind speed > 49 m s-1) in the postmonsoon BoB 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 intensification, 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 BoB, where nearly all major TCs form. These changes are part of positive linear trends, suggesting that the intensity of postmonsoon BoB TCs may continue to increase in the future.

Balaguru, Karthik; Taraphdar, Sourav; Leung, L. Ruby; Foltz, Gregory R.

2014-05-01

301

Structures of Mesocirculations Producing Tornadoes Associated with Tropical Cyclone Frances (1998)  

NASA Astrophysics Data System (ADS)

Radar structures of one mesocyclone and one mesocirculation (the term mesocirculation refers to a class of rotating updrafts, which may or may not be as spatially and temporally large as a typical mesocyclone) that developed a total of four tornadoes in association with Tropical Cyclone (TC) Frances 1998 are presented. One tornado developed within an inner rainband near the time of landfall while three of the other tornadoes developed within an outer rainband nearly 24 hours after the landfall. Radar reflectivities of the tornadic circulations averaged upwards of 40 dBZ while Doppler radar wind components directed toward the radar averaged 11 m s-1. It is realized that although TC Frances was a minimal hurricane it spawned several tornadoes (four of which were studied) causing damage exceeding 2 million. These tornadoes were not all located close to the TC center, serving as a caution to forecasters and emergency personnel that the immediate landfalling area is not the only place to watch.

Rao, Gandikota V.; Scheck, Joshua W.; Edwards, Roger; Schaefer, Joseph T.

2005-08-01

302

Variability in tornado frequency associated with U.S. landfalling tropical cyclones  

NASA Astrophysics Data System (ADS)

A statistical model for tornado frequency from Gulf of Mexico landfalling tropical cyclones (TCs) is developed using TC size, intensity, recurvature, and mid-level specific humidity data. New datasets are assembled for tornado frequency and for TC size at landfall as measured by the radius of outer closed isobar and distance of tornado from the TC center. Owing to systematic undercounting of tornadoes, the model is used to reconstruct the TC tornado climatology back to 1948, and further back to 1920 using a modified model that does not include mid-level specific humidity. Relative to the previous active period for Gulf TC landfalls of 1948-1964, the active period since 1995 has seen a statistically significant increase (95% level) in median TC tornadoes and in the frequency of large TC tornado outbreaks. These changes are linked to an increase in the median size and frequency of large Gulf landfalling TCs.

Belanger, James I.; Curry, Judith A.; Hoyos, Carlos D.

2009-09-01

303

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

NASA Technical Reports Server (NTRS)

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) in two types of experiments, using a 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.

Shaevitz, Daniel A.; Camargo, Suzana J.; Sobel, Adam H.; Jonas, Jeffery A.; Kim, Daeyhun; Kumar, Arun; LaRow, Timothy E.; Lim, Young-Kwon; Murakami, Hiroyuki; Roberts, Malcolm J.; Scoccimarro, Enrico; Wang, Hui; Wehner, Michael F.; Zhao, Ming

2014-01-01

304

Tropical cyclone kinetic energy and structure evolution in the HWRFx model  

NASA Astrophysics Data System (ADS)

Tropical cyclones exhibit significant variability in their structure, especially in terms of size and asymmetric structures. The variations can influence subsequent evolution in the storm as well as its environmental impacts and play an important role in forecasting. This study uses the Hurricane Weather Research and Forecasting Experimental System (HWRFx) to investigate the horizontal and vertical structure of tropical cyclones. Five real data HWRFx model simulations from the 2005 Atlantic tropical cyclone season (two of Hurricanes Emily and Wilma, and one of Hurricane Katrina) are used. Horizontal structure is investigated via several methods: the decomposition of the integrated kinetic energy field into wavenumber space, composite analysis of the wind fields, and azimuthal wavenumber decomposition of the tangential wind field. Additionally, a spatial and temporal decomposition of the vorticity field to study the vortex Rossby wave contribution to storm asymmetries with an emphasis on azimuthal wavenumber-2 features is completed. Spectral decomposition shows that the average low level kinetic energy in azimuthal wavenumbers 0, 1 and 2 are 92%, 6%, and 1.5% of the total kinetic energy. The kinetic energy in higher wavenumbers is much smaller. Analysis also shows that the low level kinetic energy wavenumber 1 and 2 components can vary between 0.3--36.3% and 0.1--14.1% of the total kinetic energy, respectively. The asymmetries associated with storm motion, environmental shear, and the relative orientation of these vectors are examined. A composite analysis shows a dominant wavenumber-1 asymmetry associated with the storm motion and shear vectors. For storm motion the asymmetry is located in the right front quadrant relative to the motion vector with a magnitude exceeding 2.5 m/s, and for shear the asymmetry is located 90° left of the shear vector with a magnitude exceeding 5 m/s. The locations of these wavenumber-1 asymmetries are consistent with the findings of previous studies. Further composite analysis of the asymmetries associated with the relative orientation of the storm motion and shear vectors reveals that when the vectors are aligned versus opposed the wavenumber-1 asymmetries have roughly equivalent magnitude but very different azimuthal location (when aligned the maximum is located in the left front quadrant relative to the storm motion, and when opposed is located nearly 90° to the right of the storm motion). The magnitude of the wavenumber-2 asymmetries is much larger when the storm motion and shear vectors are aligned (exceeding 2.5 m/s) than when they are opposed (˜0.5 m/s). The results indicate that shear induced asymmetries extend more deeply through the troposphere than storm motion induced asymmetries. Furthermore, the vortex Rossby wave analysis provides compelling evidence to support their existence and their contribution to the wavenumber-2 asymmetries in the simulated storms. The vertical structure is studied in terms of the relationship between the size of the radius of maximum wind and its slope, and whether the radius of maximum wind is well approximated by a constant absolute angular momentum surface. The impacts of environmental shear on these relationships are specifically examined. While there is some evidence to suggest that moderate shear can have a constructive influence on the storm, the relationships between the radius of maximum wind and its slope, and the slopes of the radius of maximum wind and the constant absolute angular momentum surface deteriorate quickly with increasing shear. The vertical warm core structure of the tropical cyclones is investigated in terms of the height and magnitude of the primary and any possible secondary warm core features (as measured in terms of the temperature anomalies). The purpose of this analysis is to determine the general warm core structure and establish if there are any significant trends with respect to storm evolution, environmental shear, or storm intensity change. It is determined that there is often a dual warm core structure with a pri

Maclay, Katherine S.

305

Stochastic Tropical Cyclone Model for the North Atlantic: SST and Landfall  

NASA Astrophysics Data System (ADS)

A stochastic North-Atlantic tropical cyclone (TC) model has been developed that includes sensitivity to SST and ENSO. The track and genesis components are revised versions of components reported by Hall and Jewson (2007). The model now includes a stochastic representation of maximum-sustained wind speed (Vmax), as the measure of intensity. All model components are based on National Hurricane Center HURDAT “best track” data. The model has been used to generate 5000 realizations of the 1950-2008 period (using historical SST and ENSO), as well as 1000-year simulations in various fixed “climate states” (fixed values for SST and ENSO). Several diagnostics are used to evaluate the model, including landfall rates on various regions of the US east and Gulf coasts. Overall, the number of US landfalls rises with SST. However, the SST-landfall sensitivity varies with geographic region and with storm intensity.

Hall, T. M.

2009-12-01

306

Statistical characteristics of meso-scale vortex effects on the track of a tropical cyclone  

NASA Astrophysics Data System (ADS)

This paper examines initial meso-scale vortex effects on the motion of a tropical cyclone (TC) in a system where coexisting two components of TC and meso-scale vortices with a barotropic vorticity equation model. The initial meso-scale vortices are generated stochastically by employing Reinaud's method. The 62 simulations are performed and analysed in order to understand the statistical characteristics of the effects. Results show that the deflection of the TC track at t = 24 h induced by the initial meso-scale vortices ranges from 2 km to 37 km with the mean value of 13.4 km. A more significant deflection of the TC track can be reduced when several initial meso-scale vortices simultaneously appear in a smaller TC circulation area. It ranges from 22 km to 37 km with the mean value of 28 km, this fact implies that the initial meso-scale vortices-induced deflection may not be neglected sometimes.

Luo, Zhe-Xian; Sun, Zhi-An; Ping, Fan

2011-04-01

307

Effect of surface waves on air-sea momentum flux under tropical cyclones  

NASA Astrophysics Data System (ADS)

Effect of surface waves on air-sea momentum flux under tropical cyclones is investigated using a wave boundary layer model. The model predicts the wind stress by explicitly calculating the wave-induced stress. In the frequency range near the spectral peak, WAVEWATCH-III is used to estimate the spectra, and the spectra in the equilibrium range is determined by an existing analytical model. This approach allows us to estimate the drag coefficient and the equivalent surface roughness for mature and growing seas as well as for complex seas forced by tropical cyclone winds. First, numerical experiments are performed for constant winds from 10 m/s to 45 m/s. The Charnock coefficient is estimated to be about 0.01 - 0.02 for fully-developed seas, which is within the range of previous observational data. With growing seas, our results for winds less than 30 m/s show that the drag coefficient is larger with younger seas, being consistent with earlier studies. For winds higher than 30 m/s, however, our results show a different trend, that is, younger waves yield less drag. This is because the wave induced stress due to very young waves makes a small contribution to the total wind stress in extremely high wind conditions. Next, numerical experiments are performed with four idealized hurricanes, i.e., stationary, slow-moving (2.5 m/s), typical-speed (5.0 m/s), and fast-moving (10 m/s). Waves to the right and front of the hurricane track become trapped as the hurricane translation speed becomes faster and waves are exposed to prolonged forcing from the wind. As a result, higher, longer and more developed waves are formed to the right and front of the track and yield higher drag coefficients, while lower, shorter and younger waves to the rear and left yield lower drag coefficients.

Moon, I.; Hara, T.; Ginis, I.; Tolman, H. L.

2003-04-01

308

MID-LATITUDE CYCLONES WITH TROPICAL ORIGINS: lessons from two historical case studies.  

NASA Astrophysics Data System (ADS)

Interest in storm and hurricane activity has grown over recent years, their changing incidence being seen, rightly or wrongly, as a gauge of ‘global warming'. Yet such judgements can be confidently offered only on the basis of a reliable long period of record that provides more informative perspective on the events of the past few decades. This presentation is concerned with two examples of hurricane activity, both of which make valuable use of historical source material but provide different lessons for climatologists. The first example is from 1680 and demonstrates the value of historical source material in reconstructing events from the distant past and suggests a way forward in developing and improving the long-term storm chronologies. The other, based on the analogous events of 1842 and 2005, offers a convincing demonstration of the need to call upon such comprehensive long-term chronologies in order to avoid making mistaken and unintentionally ill-informed observations on the seeming idiosyncrasies of recent climatic variation. The first example, from August 1680, reconstructs the trajectory and development of an Atlantic tropical cyclone, and draws upon a notable variety of documentary sources ranging from ships' logbooks, official and unofficial correspondence and some early examples of instrumental data. It serves as a model of how such sources, which remain largely unexploited, can be called upon to provide important climatic information. It allows also for the reconstruction the tropical and extratropical phases of the cyclone's trajectory and its possible impact over the UK. The second example, which compares hurricane Vince (2005) with an earlier but overlooked analogue from 1842, demonstrates the caution with which recent events should be interpreted and the need to take as long-term view as possible. Hurricane Vince, which moved directly from the eastern Atlantic towards Iberia, was widely proclaimed as a unique event and a consequence of global warming. Yet a careful search of the historical record provided an almost perfect analogue from 1842 and in doing so offered a salutary warning of our need for caution and for a clearer picture of the past. This presentation reviews both examples and discusses their implications in terms of the possibility of improving the cyclone chronology and, thereby, of assisting in our understanding of present-day events. References Vaquero J.M., R. García-Herrera, D. Wheeler, M. Chenoweth and C. J. Mock, 2008: An historical analogue of 2005 hurricane Vince. Bulletin of the American Meteorological Society, 89, 191 - 201. WheelerD., R. García-Herrera, J.M.Vaquero, M. Chenoweth and C. J. Mock, 2009: Reconstructing the trajectory of the August 1680 Hurricane from contemporary records Bulletin of the American Meteorological Society,(accepted).

García-Herrera, R.; Vaquero, J. M.; Wheeler, D.

2009-04-01

309

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)

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.

Putman, William M.

2010-01-01

310

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

NASA Astrophysics Data System (ADS)

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.

Mardhekar, D.

2010-09-01

311

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

NASA Astrophysics Data System (ADS)

The association between bi-decadal rainfall variability over southern Africa and the rainfall contributed by tropical cyclonic systems from the Southwest Indian Ocean (SWIO) provides a potential means towards understanding decadal-scale variability over parts of the region. A multi-decadal period is considered, focusing on the anomalous tropospheric patterns that induced a particularly wet 8-year long sub-period over the Limpopo River Basin. The wet sub-period was also characterized by a larger contribution to rainfall by tropical cyclones and depressions. The findings suggest that a broadening of the Hadley circulation underpinned by an anomalous anticyclonic pattern to the east of southern Africa altered tropospheric steering flow, relative vorticity and moisture contents spatially during the sub-period of 8 years. These circulation modulations induced enhanced potential for tropical systems from the SWIO to cause precipitation over the Limpopo River Basin. The same patterns are also conducive to increasing rainfall over the larger subcontinent, therefore explaining the positive association in the bi-decadal rainfall cycle and rainfall contributed by tropical cyclonic systems from the SWIO. An overview of regional circulation anomlies during alternating near-decadal wet and dry epochs is given. The regional circulation anomalies are also explained in hemispheric context, specifically in relation to the Southern Annular Mode, towards understanding variation over other parts of the Southern Hemisphere at this time scale.

Malherbe, Johan; Landman, Willem A.; Engelbrecht, Francois A.

2014-06-01

312

Explosive cyclogenesis of extra-tropical cyclone Klaus and its effects in Catalonia. A case study of hurricane force gusts.  

NASA Astrophysics Data System (ADS)

On 23th and 24th of January 2009, the extra-tropical cyclone Klaus crossed the north of Spain and the south of France producing several deaths and generalized damages. The cyclone of Atlantic origin underwent an explosive deepening of more than 1 hPa per hour at the surface level. Catalonia region was affected by gale-force winds and hurricane gusts. The Atlantic depression underwent a process called explosive cyclogenesis (when a surface cyclone deepens at a rate higher than 1 hPa/hr over 24 hours, approximately) in front of the Spanish Atlantic coasts. In this study we focus on its impact in the Catalonia areas where both synoptic and local effects were important. Also we evaluate the performance of the numerical weather prediction model outputs against observed data.

Calvo, J.; López, J. A.; Martín, F.; Morales, G.; Pascual, R.

2009-09-01

313

AIRS Impact on the Analysis and Forecast Track of Tropical Cyclone Nargis in a Global Data Assimilation and Forecasting System  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

314

Tropical Cyclone Precipitation Types and Electrical Field Information Observed by High Altitude Aircraft Instrumentation  

NASA Technical Reports Server (NTRS)

During the 1998 and 200 1 hurricane seasons of the Atlantic Ocean Basin, the Advanced Microwave Precipitation Radiometer (AMPR), the ER-2 Doppler (EDOP) radar, and the Lightning Instrument Package (LIP) were 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. A rainfall screening technique has been developed using AMPR passive microwave observations of these tropical cyclones (TC) collected at frequencies of 10.7, 19.35,37.1, and 85.5 GHz and verified using vertical profiles of EDOP reflectivity and lower altitude horizontal reflectivity scam collected by the National Oceanic and Atmospheric Administration (NOM) P-3 radar. Matching the rainfall classification results with coincident electrical field information collected by the LIP readily identifl convective rain regions within the TC precipitation fields. Strengths and weaknesses of the rainfall classification procedure will be discussed as well as its potential as a real-time analysis tool for monitoring vertical updrafl strength and convective intensity from a remotely operated or uninhabited aerial vehicle.

Hood, Robbie E.; Blakeslee, Richard; Cecil, Daniel; LaFontaine, Frank J.; Heymsfield, Gerald; Marks, Frank

2004-01-01

315

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

NASA Technical Reports Server (NTRS)

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.

Rodgers, E.; Gentry, R. C.

1983-01-01

316

Growing threat of intense tropical cyclones to East Asia over the period 1977-2010  

NASA Astrophysics Data System (ADS)

The threat of intense tropical cyclones (TCs) to East Asia has increased in recent decades. Integrated analyses of five available TC data sets for the period 1977-2010 revealed that the growing threat of TCs primarily results from the significant shift that the spatial positions of the maximum intensity of TCs moved closer to East Asian coastlines from Vietnam to Japan. This shift incurs a robust increase in landfall intensity over east China, Korea and Japan. In contrast, an increase of TC genesis frequency over the northern part of the South China Sea leads to a reduction in the maximum TC intensity before landfall, because of their short lifetime; thus, there are no clear tendencies in the landfall intensity across Vietnam, south China and Taiwan. All changes are related to the strengthening of the Pacific Walker circulation, closely linked with the recent manifestation that the warming trend of sea surface temperature in the tropical western Pacific is much higher than that in the central to eastern Pacific.

Park, Doo-Sun R.; Ho, Chang-Hoi; Kim, Joo-Hong

2014-01-01

317

Trends in tropical cyclones in the South Indian Ocean and the South Pacific Ocean  

NASA Astrophysics Data System (ADS)

The statistical significance of trends in tropical cyclones (TCs) in the South Indian Ocean (SIO) and the South Pacific Ocean (SPO) has been examined. Calculation of significance is based on nonparametric Monte Carlo methods, and in addition we explore whether a constant model, a linear model, or a simple breakpoint model represents a best fit to the data. For the 1981-1982 to 2006-2007 TC seasons, there are no apparent trends in the total numbers of TCs (by which, in this study, we mean those tropical systems attaining a minimum central pressure of 995 hPa or lower), nor in numbers of 970 hPa TCs in the SIO and the SPO (such TCs being called severe in the Southern Hemisphere). Positive trends in the numbers of 945 hPa and 950 hPa TCs in the SIO are significant but appear to be influenced to some extent by changes in data quality. In the Australian region, no significant trends in the total numbers of TCs, or in the proportion of the most intense TCs, have been found.

Kuleshov, Y.; Fawcett, R.; Qi, L.; Trewin, B.; Jones, D.; McBride, J.; Ramsay, H.

2010-01-01

318

Opportunities and challenges for extended-range predictions of tropical cyclone impacts on hydrological predictions  

NASA Astrophysics Data System (ADS)

SummaryAn opportunity exists to extend support to the decision-making processes of water resource management and hydrological operations by providing extended-range tropical cyclone (TC) formation and track forecasts in the western North Pacific from the 51-member ECMWF 32-day ensemble. A new objective verification technique demonstrates that the ECMWF ensemble can predict most of the formations and tracks of the TCs during July 2009 to December 2010, even for most of the tropical depressions. Due to the relatively large number of false-alarm TCs in the ECMWF ensemble forecasts that would cause problems for support of hydrological operations, characteristics of these false alarms are discussed. Special attention is given to the ability of the ECMWF ensemble to predict periods of no-TCs in the Taiwan area, since water resource management decisions also depend on the absence of typhoon-related rainfall. A three-tier approach is proposed to provide support for hydrological operations via extended-range forecasts twice weekly on the 30-day timescale, twice-daily on the 15-day timescale, and up to four times a day with a consensus of high-resolution deterministic models.

Tsai, Hsiao-Chung; Elsberry, Russell L.

2013-12-01

319

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

320

Tropical cyclone and extreme rainfall trends in East Asian summer monsoon since mid-20th century  

NASA Astrophysics Data System (ADS)

Proper interpretations of extreme rainfall trends in the Asian monsoon regions are complicated by tropical cyclones (TCs) from tropical oceans, whose rainfall trend may be different from the local monsoon (non-TC) rain. Here we show that the trends over the China summer monsoon region have been distorted by western North Pacific typhoons, which bring rainfall with decreasing frequency and increasing intensity. Typically the latter is not sufficient to overcome the former, so TC-related extreme rainfall trend is smaller than monsoon-related extreme rainfall. The net impact underestimates the increasing trend and overestimates the decreasing trend in monsoon extreme rainfall over most areas. The effect is minimal in the Meiyu rain belt region, but reaches 30% in northeastern and southern China. The largest distortions occur on offshore islands in the main TC paths that underwent significant decadal variations. In Hainan, the -3%/decade trend becomes +7%/decade if typhoon rainfall is removed. An opposite case occurs in Taiwan, where the extreme rainfall trend is hugely inflated by local increases in TC rainfall. These opposite effects emphasize the importance of considering the different mechanisms of rainfall systems in order to avoid mis-attribution of regional effects on extreme rainfall to thermodynamic consequences of global warming.

Chang, Chih-Pei; Lei, Yonghui; Sui, Chung-Hisung; Lin, Xiaohong; Ren, Fumin

2012-09-01

321

Investigating the Eco-Hydrological Impact of Tropical Cyclones in the Southeastern United States  

NASA Astrophysics Data System (ADS)

Tropical Cyclones (TCs) intensity and frequency are expected to be impacted by climate change. Despite their destructive potential, these phenomena, which can produce heavy precipitation, are also an important source of freshwater. Therefore any change in frequency, seasonal timing and intensity of TCs is expected to strongly impact the regional water cycle and consequently the freshwater availability and distribution. This is critical, due to the fact that freshwater resources in the US are under stress due to the population growth and economic development that increasingly create more demands from agricultural, municipal and industrial uses, resulting in frequent over-allocation of water resources. In this study we concentrate on monitoring the impact of hurricanes and tropical storms on vegetation activity along their terrestrial tracks and investigate the underlying physical processes. To characterize and monitor the spatial organization and time of recovery of vegetation disturbance in the aftermath of major hurricanes over the entire southeastern US, a remote sensed framework based on MODIS enhanced vegetation index (EVI) was developed. At the SE scale, this framework was complemented by a water balance approach to estimate the variability in hurricane groundwater recharge capacity spatially and between events. Then we investigate the contribution of TCs (season totals and event by event) to the SE US annual precipitation totals from 2002 to 2011. A water budget approach applied at the drainage basins scale is used to investigate the partitioning of TCs' precipitation into surface runoff and groundwater system in the direct aftermath of major TCs. This framework allows exploring the contribution of TCs to annual precipitation totals and the consequent recharge of groundwater reservoirs across different physiographic regions (mountains, coastal and alluvial plains) versus the fraction that is quickly evacuated through the river network and surface runoff. Then a Land surface Eco-Hydrological Model (LEHM), combining water and energy budgets with photosynthesis activity, is used to estimate Gross Primary Production (GPP) over the SE US The obtained data is compared to AmeriFlux and MODIS GPP data over the SE United States in order to establish the model's ability to capture vegetation dynamics for the different biomes of the SE US. Then, a suite of numerical experiments is conducted to evaluate the impact of Tropical Cyclones (TCs) precipitation over the SE US. The numerical experiments consist of with and without TC precipitation simulations by replacing the signature of TC forcing by NARR-derived climatology of atmospheric forcing ahead of landfall during the TC terrestrial path. The comparison of these GPP estimates with those obtained with the normal forcing result in areas of discrepancies where the GPP was significantly modulated by TC activity. These areas show up to 10% variability over the last decade.

Brun, Julien

322

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

323

Sensitivities of AGCM-Simulated Tropical Cyclones to Varying Initial Conditions  

NASA Astrophysics Data System (ADS)

General Circulation Models (GCMs) have been increasingly used to simulate Tropical Cyclones (TCs) and predict their changes due to the effects of climate warming. As such, the motivation is to examine how the development of Tropical Cyclones (TCs) is represented in Atmospheric General circulation Models (AGCMs) and assesses the impact of changes in initial conditions, which include Radius of Maximum wind speed (RMW), Maximum wind speed (MWS), Sea surface temperature (SST), Environmental lapse rate (Gamma) and mid-level relative humidity (500-hPa RH), on modeled TCs. The National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) has been used to simulate the development of idealized TCs over 10 days. A Latin Hypercube Sampling (LHS) method is used to generate two 300-member space-filling ensembles of simulations with grid resolution of 1×1 and 0.5 ×0.5 degree respectively. Composite analysis is first used to analyze the ensemble results, then, the Expanded Multivariate Adaptive Regression Splines (EMARS) method is implemented to characterize various TC response functions. Both 0.5 and 1.0 degree simulations produce a wide range of TC intensities ranging from tropical depression to category 4 or 5 on the Saffir-Simpson scale. On average, storms in the higher resolution simulations are stronger than those produced by the coarser-resolution model. Specifically, it is found that (1) the intensity, track, cloud, precipitation and radiative fields of simulated TCs are highly sensitive to changes in the initial vortex characteristics and surrounding environment; (2) nonlinear interaction between the initial conditions is crucial to the distribution of clouds, precipitation, and radiation of simulated TCs; (3) favorable initial conditions are able to produce intense and destructive TCs even in1 ×1 degree resolution global climate models; (4) inter-relationships exist among the cloud radiative forcing, cloud water content, precipitation and intensity of finally simulated TCs. The impact of the interaction between current initial conditions and the wind shear on the development and representation of simulated TCs in GCMs will also be investigated.

He, F.; Posselt, D. J.; Narisetty, N.; Zarzycki, C.; Nair, V.

2013-12-01

324

AIRS impact on precipitation analysis and forecast of tropical cyclones in a global data assimilation and forecast system  

NASA Astrophysics Data System (ADS)

The impact of assimilating quality-controlled Atmospheric Infrared Sounder (AIRS) temperature retrievals obtained from partially cloudy regions is assessed, with focus on precipitation produced by the GEOS-5 data assimilation and forecasting system, for three tropical cyclones: Nargis (April 27 - May 03, 2008) in the Indian Ocean, Wilma (October 15-26, 2005) and Helene (September 12-16, 2006) in the Atlantic. It is found that the precipitation analysis obtained when assimilating AIRS cloudy retrievals (AIRS) can capture regions of heavy precipitation associated with tropical cyclones much better than without AIRS data (CONTRL) or when using AIRS clear-sky radiances (RAD). The precipitation along the storm track shows that the AIRS assimilation produces larger mean values and more intense rain rates than the CONTRL and RAD assimilations. The corresponding precipitation forecasts initialized from AIRS analysis show reasonable prediction skill and better performance than forecasts initialized from CONTRL and RAD analyses up to day-2.

Zhou, Y. P.; Lau, K.-M.; Reale, O.; Rosenberg, R.

2010-01-01

325

Upper ocean variability in the Bay of Bengal during the tropical cyclones Nargis and Laila  

NASA Astrophysics Data System (ADS)

Upper ocean variability at different stages in the evolution of the tropical cyclones Nargis and Laila is evaluated over the Bay of Bengal (BoB) during May 2008 and May 2010 respectively. Nargis initially developed on 24 April 2008; intensified twice on 27-28 April and 1 May, and eventually made landfall at Myanmar on 2 May 2008. Laila developed over the western BoB in May 2010 and moved westward towards the east coast of India. Data from the Argo Profiling floats, the Research Moored Array for African-Asian-Australian Monsoon Analysis and prediction (RAMA), and various satellite products are analyzed to evaluate upper ocean variability due to Nargis and Laila. The analysis reveals pre-conditioning of the central BoB prior to Nargis with warm (>30 °C) Sea Surface Temperature (SST), low (<33 psu) Sea Surface Salinity (SSS) and shallow (<30 m) mixed layer depths during March-April 2008. Enhanced ocean response to the right of the storm track due to Nargis includes a large SST drop by ?1.76 °C, SSS increase up to 0.74 psu, mixed layer deepening of 32 m, shoaling of the 26 °C isotherm by 36 m and high net heat loss at the sea surface. During Nargis, strong inertial currents (up to 0.9 ms-1) were generated to the right of storm track as measured at a RAMA buoy located at 15 °N, 90 °E, producing strong turbulent mixing that lead to the deepening of mixed layer. This mixing facilitated entrainment of cold waters from as deep as 75 m and, together with net heat loss at sea surface and cyclone-induced subsurface upwelling, contributed to the observed SST cooling in the wake of the storm. A similar upper ocean response occurs during Laila, though it was a significantly weaker storm than Nargis.

Maneesha, K.; Murty, V. S. N.; Ravichandran, M.; Lee, T.; Yu, Weidong; McPhaden, M. J.

2012-11-01

326

Predictability and Prediction of Tropical Cyclones on Daily to Interannual Time Scales  

NASA Astrophysics Data System (ADS)

The spatial and temporal complexity of tropical cyclones (TCs) raises a number of scientific questions regarding their genesis, movement, intensification, and variability. In this presentation, we review the current state of predictability for each of these processes by evaluating probabilistic forecasts from the most advanced global numerical weather prediction system to date, the ECMWF Variable Resolution Ensemble Prediction System (VarEPS). Using a new false alarm clustering technique to maximize the utility of the VarEPS, the ensemble system is shown to provide well-calibrated probabilistic forecasts for TC genesis through a lead-time of one week, and pregenesis track forecasts with similar skill compared to the VarEPS's postgenesis track forecasts. To quantify the predictability of TCs on intraseasonal time scales, forecasts from the ECMWF Monthly Forecast System (ECMFS) are examined for the North Atlantic Ocean. From this assessment, dynamically based forecasts from the ECMFS provide forecast skill exceeding climatology out to weeks three and four for portions of the southern Gulf of Mexico, western Caribbean and the Main Development Region. Forecast skill in these regions is traced to the model's ability to capture correctly the variability in deep-layer vertical wind shear, the relative frequency of easterly waves moving through these regions, and the intraseasonal modulation of the Madden-Julian Oscillation. On interannual time scales, the predictability of TCs is examined by considering their relationship with tropical Atlantic easterly waves. First, a set of easterly wave climatologies for the CFS-R, ERA-Interim, ERA-40, and NCEP/NCAR Reanalysis are developed using a new easterly wave-tracking algorithm. From the reanalysis-derived climatologies, a moderately positive and statistically significant relationship is seen with tropical Atlantic TCs. In relation to large-scale climate modes, the Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Mode (AMM) exhibit the strongest positive covariability with Atlantic easterly wave frequency. Besides changes in the number of easterly waves, the intensification efficiency of easterly waves has also been evaluated. These findings offer a plausible physical explanation for the recent increase in the number of tropical Atlantic TCs, as it has been concomitant with an increasing trend in both the number of tropical Atlantic easterly waves and intensification efficiency.

Belanger, J. I.

2012-12-01

327

Application of conditional non-linear optimal perturbations to tropical cyclone adaptive observation using the Weather Research Forecasting (WRF) model  

NASA Astrophysics Data System (ADS)

Conditional non-linear optimal perturbation (CNOP), which is a natural extension of the linear singular vector into the non-linear regime, has been suggested to identify data-sensitive regions in the adaptive observation strategy. CNOP is the global maximum of a cost function, whereas, local CNOP is the local maximum of the cost function if the local maximum exists. The potential application of CNOPs to tropical cyclone adaptive observation is researched. The CNOPs and the first singular vector (FSV) are numerically obtained by a spectral projected gradient algorithm with the Weather Research Forecasting (WRF) model. This paper examines two tropical cyclone cases, a fast straight moving typhoon Matsa (2005) and a slow moving recurving typhoon Shanshan (2006). The CNOPs and FSVs are obtained using the norms of background error at initial time and total dry energy at final time with a 36-h optimization time interval. The spatial structures of CNOPs, their energies, non-linear evolutions and impacts on track simulations are compared with those of the FSVs. The results show that both the CNOPs and the FSVs are localized, and evolve into the verification area at the final time with the upscale growth of perturbations. However, the CNOPs are different from the FSVs in spatial patterns, wind maximum distribution, growth rate of energy and impact on track simulation. Compared to FSV, CNOP and local CNOP have greater impact on the forecast in the verification region at the final time in terms of total energy, and have larger, at least similar impact on track simulation too. This indicates the CNOP method with constraint of the norm of background error at initial time and total energy norm at final time is a reasonable candidate in tropical cyclone adaptive observation. Therefore, both CNOP and local CNOP are suggested to be considered in tropical cyclone adaptive observation.

Wang, Hongli; Mu, Mu; Huang, Xiang-Yu

2011-10-01

328

Observations of Thermal and Precipitation Structure in a Tropical Cyclone by Means of Passive Microwave Imagery near 118 GHZ  

Microsoft Academic Search

An imaging microwave radiometer with eight double-sideband channels centered on the 118-GHz oxygen resonance was flown on a high-altitude aircraft over a tropical cyclone in the Coral Sea. The measurements clearly resolved an eyewall of strong convection and a warm core within the eye. Brightness temperatures observed within the eye were approximately 10 K warmer than those observed in clear

M. J. Schwartz; J. W. Barrett; P. W. Fieguth; P. W. Rosenkranz; M. S. Spina; D. H. Staelin

1996-01-01

329

Tropical cyclone genesis frequency over the western North Pacific simulated in medium-resolution coupled general circulation models  

Microsoft Academic Search

This study examines the tropical cyclone (TC) genesis frequency over the western North Pacific simulated in atmosphere–ocean\\u000a coupled general circulation models from the World Climate Research Programme’s Coupled Model Intercomparison Project phase\\u000a 3. We first evaluate performances of eight models with atmospheric horizontal resolution of T63 or T106 by analyzing their\\u000a daily-mean atmospheric outputs of twentieth-century climate simulations available from

Satoru Yokoi; Yukari N. Takayabu; Johnny C. L. Chan

2009-01-01

330

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

NASA Astrophysics Data System (ADS)

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.

Griffin, Kyle S.

331

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)

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.

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

2011-12-01

332

Gulf of Mexico Loop Current mechanical energy and vorticity response to a tropical cyclone  

NASA Astrophysics Data System (ADS)

The ocean mixed layer response to a tropical cyclone within, and immediately adjacent to, the Gulf of Mexico Loop Current is examined using a combination of ocean profiles and a numerical model. A comprehensive set of temperature, salinity, and current profiles acquired from aircraft-deployed expendable probes is utilized to analyze the three-dimensional oceanic energy and circulation evolution in response to Hurricane Lili's (2002) passage. Mixed-layer temperature analyses show that the Loop Current cooled <1° C in response to the storm, in contrast to typically observed larger decreases of 3-5° C. Correspondingly, vertical current shears, which are partly responsible for entrainment mixing, were found to be up to 50% weaker, on average, than observed in previous studies within the directly-forced region. The Loop Current, which separates the warmer, lighter Caribbean Subtropical water from the cooler, heavier Gulf Common water, was found to decrease in intensity by -0.18 +/- 0.25 m s-1 over an approximately 10-day period within the mixed layer. Contrary to previous tropical cyclone ocean response studies which have assumed approximately horizontally homogeneous ocean structure prior to storm passage, a kinetic energy loss of 5.8 +/- 6.3 kJ m-2, or approximately -1 wind stress-scaled energy unit, was observed. Using near-surface currents derived from satellite altimetry data, the Loop Current is found to vary similarly in magnitude, suggesting storm-generated energy is rapidly removed by the pre-exiting Loop Current. Further examination of the energy response using an idealized numerical model reveals that due to: (1) favorable coupling between the wind stress and pre-existing current vectors; and (2) wind-driven currents flowing across the large horizontal pressure gradient; wind energy transfer to mixed-layer kinetic energy can be more efficient in these regimes as compared to the case of an initially horizontally homogeneous ocean. However, nearly all of this energy is removed by advection by 2 local inertial periods after storm passage, and little evidence of the storm's impact remains. Mixed-layer vorticity within the idealized current also shows a strong direct response, but little evidence of an near-inertial wave wake results.

Uhlhorn, Eric Walter

333

Tropical cyclone inundation potential on the Hawaiian Islands of Oahu and Kauai  

NASA Astrophysics Data System (ADS)

The lack of a continental shelf in steep volcanic islands leads to significant changes in tropical cyclone inundation potential, with wave setup and runup increasing in importance and wind driven surge decreasing when compared to more gently-sloped mainland regions. This is illustrated through high resolution modeling of waves, surge, and runup on the Hawaiian Islands of Oahu and Kauai. A series of hurricane waves and water levels were computed using the SWAN + ADCIRC models for a suite of 643 synthetic storm scenarios, while local wave runup was evaluated along a series of 1D transects using the phase-resolving model Bouss1D. Waves are found to be an extremely important component of the inundation, both from breaking wave forced increases in storm surge and also from wave runup over the relatively steep topography. This is clear in comparisons with debris lines left by Hurricane Iniki on the Island of Kauai, where runup penetration is much greater than still water inundation in most instances. The difference between steeply-sloping and gently-sloping topographies was demonstrated by recomputing Iniki with the same landfall location as Hurricane Katrina in Louisiana. Surge was greatly increased for the mild-slope Iniki-in-Louisiana case, while pure wind surge for Iniki-in-Kauai was very small. For the entire suite of storms, maxima on Kauai show predicted inundation largely confined to a narrow coastal strip, with few locations showing more than a few hundred meters of flooding from the shoreline. As expected, maximum flooded areas for the 643 storms were somewhat greater than the Iniki inundation. Oahu has significantly more low-lying land compared to Kauai, and consequently hypothetical tropical cyclone landfalls show much more widespread inundation. Under direct impact scenarios, there is the potential for much of Honolulu and most of Waikiki to be inundated, with both still water surge and wave runup contributing. Other regions of Oahu show inundation confined to a more narrow coastal strip, although there is still much infrastructure at risk. Even for very strong storms in Oahu and Kauai, maximum still water surge is relatively small, and does not exceed 3 m in any storm modeled. In contrast, hurricane waves several kilometers from shore regularly exceed 10 m due to the lack of a continental shelf.

Kennedy, Andrew B.; Westerink, Joannes J.; Smith, Jane M.; Hope, Mark E.; Hartman, Michael; Taflanidis, Alexandros A.; Tanaka, Seizo; Westerink, Hans; Cheung, Kwok Fai; Smith, Tom; Hamann, Madeleine; Minamide, Masashi; Ota, Aina; Dawson, Clint

2012-08-01

334

The JPL Tropical Cyclone Information System: Methods for Creating Near Real-Time Science Data Portals  

NASA Astrophysics Data System (ADS)

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 JPL TCIS was made public in 2008 and initially served as a data and plot archive for past storms. More recently, the TCIS has expanded its functionality to provide near real-time (NRT) data portals for specific science field campaigns, such as the Genesis and Rapid Intensification Processes (GRIP) campaign in 2010 and ongoing Hurricane and Severe Storm Sentinel (HS3) campaign. These NRT portals allow campaign team members to look at current conditions in the geographical domain of interest. Creating the NRT portals has been particularly challenging due to (1) the wide breadth of data that needs to be collected, (2) the number of data product plots that need to be served to the user, (3) the mechanics of the search and discovery tools, and (4) the issue of how to display multiple data plots at once in a meaningful way. Recently, the TCIS team has been working to redevelop the NRT portals with these challenges in mind. The new architecture we created allows for configurable mission portals that can be created on the fly. In addition to a new database that handles portal configuration, these updated NRT portals also support an improved navigation method that allows users to see what data is available, as well as a resizable visualization area based on the users' client. The integration of the NRT portal with the NASA Earth Observing System Simulators Suite (NEOS3) and a set of new online data analysis tools allows users to compare the observation and model outputs directly and perform statistical analysis with multiple datasets. In this poster, we will present the methods and practices we used to create configurable portals, gather and plot science data with low latencies, design a navigation scheme that supports multiple data sources and missions, and develop a new web front end that is as intuitive as it is informative.

Knosp, B.; Li, P.; Vu, Q.; Hristova-Veleva, S. M.; Turk, F. J.; Shen, T.; Poulsen, W. L.; Lambrigtsen, B.

2013-12-01

335

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

NASA Technical Reports Server (NTRS)

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.

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

336

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

337

Impact of tropical cyclone development on the instability of South Asian High and the summer monsoon onset over Bay of Bengal  

NASA Astrophysics Data System (ADS)

This paper analyzes the evolution of the South Asian High (SAH) during and after the development of tropical cyclone Neoguri over the South China Sea (SCS) in mid-April 2008, the formation of tropical storm Nargis over the Bay of Bengal (BOB) in late April, and the Asian summer monsoon onset, as well as their interrelationships. Numerical sensitivity experiments are conducted to explore the underlying mechanism responsible for these seasonal transitions in 2008. It is demonstrated that strong latent heating related with tropical cyclone activities over the SCS can enhance the development of the SAH aloft and generate zonal asymmetric potential vorticity (PV) forcing, with positive vorticity advection to its east and negative advection to its west. Following the decay of the tropical cyclone, this asymmetric forcing leads to instability development of the SAH, presenting as a slowly westward-propagating Rossby wave accompanied by a westward shift of the high PV advection. A strong upper tropospheric divergence on the southwest of the SAH also shifts westward, while positive PV eddies are shed from the high PV advection and eventually arrives in the southern BOB. Such synoptic patterns provide favorable pumping conditions for local cyclonic vorticity to develop. The latent heating release from the cyclogenesis further intensifies the upper-layer divergence, and the lower and upper circulations become phase locked, leading to the explosive development of the tropical cyclone over the southern BOB. Consequently, a tropical storm is generated and the BOB summer monsoon commences.

Wu, Guoxiong; Ren, Suling; Xu, Jianmin; Wang, Dongxiao; Bao, Qing; Liu, Boqi; Liu, Yimin

2013-11-01

338

Predicting tropical cyclone rapid intensification using the 37 GHz ring pattern identified from passive microwave measurements  

NASA Astrophysics Data System (ADS)

A distinctive satellite-derived precipitative ring pattern around the tropical cyclone (TC) center is found to be related to rapid intensification (RI). The ring pattern appears on the Naval Research Laboratory (NRL) 37 GHz passive microwave composite color product as a cyan color ring. The probability of RI is evaluated for cases with this ring pattern by reviewing images of the NRL product for 84 TCs during 2003-2007 in the Atlantic basin using 6-hourly National Hurricane Center (NHC) best track data. It is found that when combining the ring criterion with the Statistical Hurricane Prediction Scheme (SHIPS) RI Index (RII), the probability of RI almost doubled, indicating that both the ring and SHIPS RII contain independent information for RI prediction. A subjective technique for predicting RI is proposed using both the 37 GHz ring and the SHIPS RII. Both the probability of detection (POD) and the false alarm ratio (FAR) for the combined ring+SHIPS RII are lower than those for SHIPS RII alone (POD, 24% versus 77%, and FAR, 26% versus 66%) when treating every 6-hr synoptic time as a separate case. Since the method was initially developed for RI event-based forecasts, statistics based on 2003-2007 Atlantic RI events, which consist of a contiguous period where any 24-hour subset shows at least a 30 kt intensity increase, are also generated. The method captures 21 out of these 28 events and produces 2 false alarms, producing a POD of 75% and a FAR of 9%.

Kieper, Margaret E.; Jiang, Haiyan

2012-07-01

339

Numerical simulations and observations of surface wave fields under an extreme tropical cyclone  

USGS Publications Warehouse

The performance of the wave model WAVEWATCH III under a very strong, category 5, tropical cyclone wind forcing is investigated with different drag coefficient parameterizations and ocean current inputs. The model results are compared with field observations of the surface wave spectra from an airborne scanning radar altimeter, National Data Buoy Center (NDBC) time series, and satellite altimeter measurements in Hurricane Ivan (2004). The results suggest that the model with the original drag coefficient parameterization tends to overestimate the significant wave height and the dominant wavelength and produces a wave spectrum with narrower directional spreading. When an improved drag parameterization is introduced and the wave-current interaction is included, the model yields an improved forecast of significant wave height, but underestimates the dominant wavelength. When the hurricane moves over a preexisting mesoscale ocean feature, such as the Loop Current in the Gulf of Mexico or a warm-and cold-core ring, the current associated with the feature can accelerate or decelerate the wave propagation and significantly modulate the wave spectrum. ?? 2009 American Meteorological Society.

Fan, Y.; Ginis, I.; Hara, T.; Wright, C.W.; Walsh, E.J.

2009-01-01

340

Assessing the influence of the ENSO on tropical cyclone prevailing tracks in the western North Pacific  

NASA Astrophysics Data System (ADS)

Using a statistical model for simulating tropical cyclone (TC) formation and a trajectory model for simulating TC tracks, the influence of the El Niño-Southern Oscillation (ENSO) on the peak-season (July-September) TC prevailing tracks in the western North Pacific basin is assessed based on 14 selected El Niño and 14 selected La Niña years during the period 1950-2007. It is found that the combination of statistical formation model and a trajectory model can simulate well the primary features of TC prevailing tracks on the interannual timescale. In the El Niño years, the significant enhancement of TC activity primarily occurs south of 20°N, especially east of 130°E. TCs that take the northwestward prevailing track and affect East Asia, including Taiwan Island, the Chinese mainland, Korea, and Japan, tend to move more westward in the El Niño years, while taking a more northward track in the La Niña years. Numerical simulations confirm that the ENSO-related changes in large-scale steering flows and TC formation locations can have a considerable influence on TC prevailing tracks.

Zhao, Haikun; Wu, Liguang; Zhou, Weican

2010-11-01

341

Seasonal prediction for tropical cyclone frequency around Taiwan using teleconnection patterns  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

342

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

343

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

344

Distribution characteristics of the intensity and extreme intensity of tropical cyclones influencing China  

NASA Astrophysics Data System (ADS)

To address the deficiency of climatological research on tropical cyclones (TCs) influencing China, we analyze the distributions of TCs with different intensities in the region, based on the best-track TC data for 1949-2011 provided by the Shanghai Typhoon Institute. We also present the distributions of 50- and 100-yr return-period TCs with different intensities using the Gumbel probability distribution. The results show that TCs with different intensities exert distinctive effects on various regions of China and its surrounding waters. The extreme intensity distributions of TCs over these different regions also differ. Super and severe typhoons mainly influence Taiwan Island and coastal areas of Fujian and Zhejiang provinces, while typhoons and TCs with lower intensities influence South China most frequently. The probable maximum TC intensity (PMTI) with 50- and 100-yr return periods influencing Taiwan Island is below 890 hPa; the PMTI with a 50-yr return period influencing the coastal areas of Fujian and Zhejiang provinces is less than 910 hPa, and that with a 100-yr return period is less than 900 hPa; the PMTI with a 50-yr return period influencing the coastal areas of Hainan, Guangdong, and the northern part of the South China Sea is lower than 930 hPa, and that with a 100-yr return period is less than 920 hPa. The results provide a useful reference for the estimation of extreme TC intensities over different regions of China.

Zheng, Yongguang; Chen, Jiong; Tao, Zuyu

2014-06-01

345

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

NASA Technical Reports Server (NTRS)

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.

Hall, Timothy; Yonekura, Emmi

2013-01-01

346

Tropical cyclone influence on the higher ionosphere from tomography sounding data over Sakhalin island  

NASA Astrophysics Data System (ADS)

In this paper the tomography sounding data (measured in 2007) are considered for the following 3 points: Uzhnosahalinsk (46°57'N, 142°44' E), Poronajsk (49°13' N, 143° 6' E) and Nogliki (51°49' N, 143°7'E). The aim of this research is to find the possible influence of a tropical cyclone (TC) on the higher ionosphere. The results demonstrate that values for critical frequency in the F2- layer (as measured at approximately 3000 km from the TC centre in a horizontal plane along the longitudinal direction) fall after several days. Also the foF2 values increased over a 1 or 2 day period near the TC active zone (in the longitudinal direction). Complexities of the morphological analysis of the given phenomenon arise because the TC is wide-spread (in a longitudinal direction, and to a much smaller degree in a horizontal direction) and a long-term source of disturbance. A major difficulty posed to our study is that the TC is wide-spread and long-lived.

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

2010-09-01

347

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

PubMed Central

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

Tweel, Andrew W.; Turner, R. Eugene

2012-01-01

348

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

PubMed

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

Tweel, Andrew W; Turner, R Eugene

2012-01-01

349

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)

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.

Chaudhuri, Sutapa; Dutta, Debashree

2014-09-01

350

The Effects of Tropical Cyclones on Sediment Transport Patterns Adjacent to a Hardbottom Reef in Onslow Bay, North Carolina  

NASA Astrophysics Data System (ADS)

An instrumented frame has been maintained on the mid-continental shelf in Onslow Bay, North Carolina, approximately 43.5 km off the coast of Wilmington, as part of the Coastal Ocean Research and Monitoring Program (CORMP) at the University of North Carolina at Wilmington. The attached instrumentation includes a downward looking Pulse-Coherent Acoustic Doppler Profiler (PC-ADP), which measures boundary layer conditions in the lower 1.5 m above the seabed, and an upward-looking Acoustic Doppler Current Profiler (ADCP) which measures velocity profiles in the upper water column. The frame was present on the shelf during the passage of four tropical cyclones that occurred between September 2003 and September 2004. All four tropical systems varied in their angle of approach, duration, and intensity as they passed by the study site. Simultaneous measurements of flow velocities from the surface to the seabed, along with acoustic backscatter measurements and seabed elevation data, have been obtained during these tropical storm events. Wave orbital velocities and mean current speeds at 1 m above the bed were used to calculate bed shear stresses during the events using the Styles and Glenn bottom boundary layer model (2000). The magnitude of suspended sediment transport during each tropical cyclone event has been quantified and characterized. In addition, the effects that a nearby hardbottom reef may have on the sediment transport patterns in the vicinity of the study site have also been examined.

Wren, A.; Leonard, L. A.

2004-12-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

352

Is the Future State of North American Hydroclimatology Controlled by Tropical Cyclones and the Evolution of El Niño?  

NASA Astrophysics Data System (ADS)

A robust projection by climate models for future global warming is a drying of the semi-arid regions including the American Southwestern United States. More uncertain hydroclimate predictions lie in heavily populated areas like India and Africa. Given the importance of equatorial Pacific ocean-atmosphere interactions for precipitation in this region, it is likely the future conditions will reflect both the global scale robust response and regional teleconnected responses to tropical sea surface temperature gradient changes. This study drives an atmospheric general circulation model with sea surface temperature anomalies derived from ocean model simulations incorporating effects of increased tropical cyclone activity. The cyclone-induced ocean temperature anomalies produce a mean state that resembles a classic El Niño signature and this pattern is used to perturb modern and future climate simulations to evaluate their impact on global and regional hydroclimatology. The cyclone-induced El Niño produces positive precipitation anomalies over the American Southwest offsetting future decreases in precipitation driven by anthropogenic carbon dioxide increases. Additionally, positive precipitation anomalies occur over India and Africa indicating a shift in the global monsoon circulation. The results suggest that robust global patterns of precipitation change in a warmer world could be altered over substantial regions by processes not well represented by current climate models.

Goldner, A. P.; Huber, M.; Sriver, R. L.

2010-12-01

353

High resolution ensemble error growth and dimensionality in tropical cyclone genesis environments  

NASA Astrophysics Data System (ADS)

Over the last several decades, ensemble forecasts of atmospheric phenomena have become increasingly popular, not only because they provide an improved mean forecast of various events, but also because they render an estimate of the accompanying forecast uncertainty. Research into high-resolution ensembles based in the Tropics and in terms of tropical cyclone (TC) genesis mechanisms has been relatively sparse, even though such disturbances are notoriously difficult to forecast. In this study, we couple several popular ensemble perturbation methods to the mesoscale Weather Research and Forecasting (WRF) model at high resolution to examine the predictability of genesis, error growth characteristics, and underdispersion issues in forecasts of Hurricane Ernesto (2006) and Typhoon Nuri (2008). In order to examine the effects of model resolution on TC genesis forecasts, a downscaled 5-km resolution regional control ensemble, based on a downscaling of the National Centers for Environmental Prediction's Global Ensemble Forecast System (GEFS), is compared against the standard GEFS simulations. To analyze the effect of the various perturbation methods on genesis and forecast characteristics, we compare results from the regional GEFS-based simulation to several implementations of the breeding of growing modes (BGM), wherein we vary the variables perturbed, cycling period durations, and boundary conditions. While the global GEFS forecast failed to predict a well-developed Ernesto in any of its members, the high-resolution GEFS-based ensemble contained several intense TCs by actual genesis time. Based on a sample of 154 ensemble member forecasts, the impact of environmental precursors on TC genesis likelihood is investigated. Despite the large number of easterly waves that do not develop into TCs and the large amount of water vapor in the summer Tropics, we find that the strength of the preexisting wave and initial 850 hPa water vapor are significant determining factors for TC genesis. Finally, we create several ensemble forecasts of Ernesto using the stochastic kinetic-energy backscatter scheme (SKEBS) and find that the standard SKEBS ensemble has more dispersion per unit error compared with both the BGM and GEFS-based ensembles. In addition, SKEBS shows notably lower vapor bias and larger theta bias compared with the initial condition-based ensembles.

Thatcher, Levi Sterling

354

New ECMWF ensemble products based on an extra-tropical cyclone tracker, and their utilisation in warning provision  

NASA Astrophysics Data System (ADS)

Algorithms for identifying and tracking extra-tropical cyclonic features that were initially developed at the Met Office have now been applied to the ECMWF ensemble, and expanded. A wide range of real-time web-based forecast products are being created from the output. These products assist with day to day forecasting, and in particular can provide alerts regarding the likelihood of extreme weather in the next 15 days. We are relying here on the fact that cyclonic features are the primary synoptic-scale cause of extreme rainfall over large catchments, extreme snowfall and extreme windstorms. Moreover, prolonged heat in summer, protracted cold in winter and drought can all relate to the absence of cyclonic activity, and so for anticipating these hazards too the products can also be a useful tool. After providing a brief overview of how the identification and tracking work, the bulk of the talk will illustrate the new products that are becoming available, and will show, with examples from the last 12 months, how these can be used to forecast extreme weather. Products include storm-track strike probabilities for different thresholds, feature-specific plume diagrams, objective front spaghetti plots, and cyclonic feature 'dalmatian' plots showing various cyclone attributes. There are also clickable links to quickly visualise, in synoptic chart format, those ensemble members that depict the most extreme evolutions. There is potential to develop similar 'products', in an aggregated way, from reanalysis data, and from climate model simulations of present and future climate. Intercomparison of data from these three categories can then hopefully provide policy-makers with a clearcut reference point for anticipating changes in extremes. This opportunity will be discussed in the context of the IMILAST project.

Hewson, Tim

2010-05-01

355

The opposite effects of inner and outer sea surface temperature on tropical cyclone intensity  

NASA Astrophysics Data System (ADS)

suite of semiidealized numerical experiments are conducted to investigate the sensitivity of tropical cyclone (TC) intensity to changes of sea surface temperature (SST) over different radial extents. It is found that the increase of inner SST within the range 1.5-2.0 times the radius of maximum wind (RMW), defined as the effective radius (ER), contributes greatly to the increase of TC intensity and the reduction of TC inner-core size, whereas the increase of outer SST (defined as SST outside the ER) reduces TC intensity and increases TC inner-core size. Further analysis suggests that the effects of SST inside and outside the ER on TC intensity rely on the factors that influence the TC development. As the SST increases inside the ER, more surface enthalpy flux enters the TC eyewall and less enters the outer spiral rainbands. This will decrease the RMW, leading to a smaller eyewall radius where strong latent heating is released. As a result, the central pressure of the TC deepens with stronger radial pressure gradient. Meanwhile, the difference between SST and upper tropospheric temperature increases. All factors above contribute to TC intensification as the inner SST increases. The opposite happens as the SST increases outside the ER. How TC intensity responds to the change of the entire SST depends on the competitive and opposite effects of inner and outer SST. Moreover, understanding the mechanisms is vital to the forecast of variations in TC intensity and inner-core size when a TC comes across an ocean cold or warm pool.

Sun, Yuan; Zhong, Zhong; Yi, Lan; Ha, Yao; Sun, Yimei

2014-03-01

356

Does Tropical Cyclone Modification Make Sense? A Decision-Analytic Assessment  

NASA Astrophysics Data System (ADS)

Since the demise of project Stormfury in 1983, little attention has been devoted to the possibility of intentionally modifying tropical cyclones (TC). However, following Hurricane Katrina and three other Category 5 hurricanes (Emily, Rita, and Wilma), which together resulted in at least 2,280 deaths and over $120-billion in damages (Blake et al., 2007), the U.S. Department of Homeland Security (DHS) has recently begun to support an effort to identify and evaluate hurricane mitigation strategies through Project HURRMIT ([http://www.ofcm.noaa.gov/ihc09/Presentations/Session10/s10-01Woodley.ppt]). Using a decision analytic framing and FEMA's HAZUS-MH MR3 damage model (http://www.fema.gov/plan/prevent/hazus/]), this paper asks, how sure must one be that an intervention will reduce TC damages before choosing to undertake a program of modification? The analysis is formulated in probabilistic terms, and assesses net benefits. In contrast to a much earlier application of decision analysis to TC-modification (Howard et al., 1972) , this work uses census data on the value of property at risk, and prior distributions on changing storm behavior based on data from hurricanes approaching the east coast of Florida since 1953. Even before considering both issues of liability that may arise from the fact that a modified storm is no longer "an act of God" as well as unforeseen environmental consequences, our results suggest that while TC modification techniques will likely alter TC behavior, one will have to be significantly more confident of the predictability and effectiveness of modification methods before their use can be justified. This work is supported by the Climate Decision Making Center through a cooperative agreement between the National Science Foundation (SES-0345798) and Carnegie Mellon University.

Klima, K.; Morgan, M. G.; Grossmann, I.

2009-12-01

357

The effects of ocean feedback on tropical cyclone energetics under idealized air-sea interaction conditions  

NASA Astrophysics Data System (ADS)

effects of ocean feedback on the energetic characteristics of the tropical cyclone (TC) are investigated based on idealized TC-ocean coupling simulations. Results reveal notable impacts of ocean response on TC energetics. The ocean feedback reduces the latent energy of TCs, and consequently less latent heat is released in TC clouds, which leads to an evident decrease of the kinetic energy. A bulk equivalent potential temperature (?e) budget analysis demonstrates that the upward heat fluxes at the top of the boundary layer, of comparable magnitudes with the surface heat fluxes, are significantly diminished by the ocean feedback. A relatively higher portion of energy extracted from the ocean has been retained by the boundary layer under influences of the ocean feedback. The air parcels in contact with the cold wake possess evidently lowered moist static energy. To evaluate the evolution of moist static energy following these cooled air parcels, a three-dimensional Lagrangian analysis is conducted using a large sample of trajectory seeds. Statistical results indicate that there is a mixing process between the cooled and ambient air parcels that lasts mostly less than 240 min. Over 70% of the seeded air parcels approach to a radius of 30-90 km from the TC center before they obtain adequate energy from surrounding air to balance their negative asymmetric ?e. Most of the cooled air parcels are warmed up in the boundary layer, thereby producing impacts on TC energetics through changing directly the moist static energy of the boundary layer. More work of real case simulations is required to generalize the findings reported herein.

Ma, Zhanhong; Fei, Jianfang; Huang, Xiaogang; Cheng, Xiaoping

2013-09-01

358

The Influence of Atlantic Tropical Cyclones on Drought over the Eastern US (1980-2007)  

NASA Astrophysics Data System (ADS)

The historical impact of tropical cyclones (TCs) on droughts in the eastern US has been poorly understood due to their different temporal and spatial scales. To assess the influence of North Atlantic TCs on the eastern US drought regime, the Variable Infiltration Capacity (VIC) land surface hydrologic model was run over the eastern US forced by the NLDAS-2 analysis with and without TC related precipitation for 1980-2007. A drought is defined in terms of soil moisture as a prolonged period below a threshold corresponding to a certain soil moisture percentile. Different duration droughts are analyzed: short-term (longer than 30 days) and long-term (longer than 90 days); and for different drought severities corresponding to the 10th, 15th, and 20th percentiles. The difference between the two VIC simulations shows the impact of TCs and this is examined at local and regional scales. Overall, the impacts of TCs included shorter drought duration and reduction of the spatial extent of drought. For example, despite its devastating impacts, Hurricane Katrina in 2005 played a key role in the evolution of drought depending on the location relative to landfall: 1) late drought initiation, 2) weak drought persistence, and 3) early drought recovery. Our results indicate that TCs decreased the duration of moderately severe, short-term (long-term) droughts by more than 150 days (100 days) and removed at least two short-term and one long-term drought events over more than 50% of the eastern US during 1980-2007. We also found that TCs impeded drought initiation mainly along the coastlines of the Gulf of Mexico and Atlantic southern states and advanced drought recovery especially for the states of Louisiana and Virginia. This study highlights the veiled benefits of North Atlantic TCs in the alleviation and removal of drought with important implications for water resources and agriculture despite their huge direct damages.

Kam, J.; Sheffield, J.; Yuan, X.; Wood, E. F.

2012-12-01

359

Variability of tropical cyclone in high frequent occurrence regions over the western North Pacific  

NASA Astrophysics Data System (ADS)

In this study, three high frequent occurrence regions of tropical cyclones (TCs), i.e., the northern South China Sea (the region S), the south Philippine Sea (the region P) and the region east of Taiwan Island (the region E), are defined with frequency of TC's occurrence at each grid for a 45-year period (1965-2009), where the frequency of occurrence (FO) of TCs is triple the mean value of the whole western North Pacific. Over the region S, there are decreasing trends in the FO of TCs, the number of TCs' tracks going though this region and the number of TCs' genesis in this region. Over the region P, the FO and tracks demonstrate decadal variation with periods of 10-12 year, while over the region E, a significant 4-5 years' oscillation appears in both FO and tracks. It is demonstrated that the differences of TCs' variation in these three different regions are mainly caused by the variation of the Western Pacific Subtropical High (WPSH) at different time scales. The westward shift of WPSH is responsible for the northwesterly anomaly over the region S which inhibits westward TC movement into the region S. On the decadal timescale, the WPSH stretches northwestward because of the anomalous anticyclone over the northwestern part of the region P, and steers more TCs reaching the region P in the greater FO years of the region P. The retreating of the WPSH on the interannual time scale is the main reason for the FO's oscillation over the region E.

Yang, Yuxing; Huang, Fei; Wang, Faming

2014-06-01

360

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

361

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

E-print Network

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...

Millier, Vicki Anne

2012-06-07

362

A History of Tropical Cyclone Events, their Spatial-temporal Distributions and Effects in Bangladesh  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TCs) frequently devastate large areas, take numerous lives, and damage extensive property in the coastal and island areas of Bangladesh. A review of the literature about cyclone events in Bangladesh indicates that previous research has mainly focused on events occurring after AD1959. In addition, limited work has examined historical data in order to understand the spatial-temporal pattern of TC occurrences and their associated losses. We rectify this gap by developing a new TC database that goes beyond the present regional TC databases by maximising the use of all available documentary sources. We then analyse the spatial-temporal pattern of TC occurrence and reconstruct their effects in Bangladesh. This new database consists of 254 TCs that occurred between AD1000 and 2009 in the Bay of Bengal (BoB). A total of 184 events directly struck Bangladesh between AD1484 and 2009. Of these 184 events, the precise location of landfall was not available for 11 events. Of the remaining 173 events, Chittagong was struck by 43 TCs, Barisal and Khulna by 42 each. Noakhali and Cox's Bazar were struck by 29 and 17 TCs respectively. Although, Chittagong was struck by more TC landfalls than any other coastal segment, Barisal was identified as high-risk place in terms of the occurrence of deaths. The findings suggest that prior to AD1900, there is a lack of data on the occurrence of TCs and this paucity of data increases the further back in time. Within the new dataset, inconsistencies in reported storm surge height, wind speed and exaggerations in the reporting of deaths are identified and discussed. In Bangladesh, a total of 2,665,636 human deaths occurred in association with the 184 TCs between AD1484 and 2009. Between AD1923 and 2009, 13 TCs caused 9,431,225 people to become homeless. Analysis of the deaths and damage associated with TCs in AD1970, AD1991 and AD2007 indicate that whilst the number of deaths decreased between events, the amount of economic damage and the number of people being affected and becoming homeless, increased significantly. The highly positive correlation (r = 0.89) between storm surge height and human deaths suggests that the occurrence of deaths increases with an increase in storm surge height. On the other hand, the increase in human injuries is mainly associated with (r = 0.51) an increase in wind speed of TC. We recognise that our new TC database for the BoB is incomplete and as such, only provides a partial picture useful for quantifying regional hazard. As such, we suggest further 'deep' archival research coupled with regional geological studies of palaeostorm surge events to gain a more sophisticated understanding of the hazard.

Alam, M. E.; Dominey-Howes, D.; Momtaz, S.; Calgaro, E.

2012-12-01

363

Downscaling tropical cyclone activity using regional models: Impact of air-sea coupling on the frequency and intensity of Atlantic hurricanes Authors: Jen-shan Hsieh, Mingkui Li, R. Saravanan, and Ping Chang Texas A & M University, College Station, TX  

NASA Astrophysics Data System (ADS)

Tropical cyclones are an important component of climate variability in the tropics and the subtropics. Unfortunately, these cyclones are poorly represented in coarse-resolution global general circulation models. Fine-resolution regional atmospheric models can be used to better simulate the properties of tropical cyclones, typically using specified sea surface temperature as the lower boundary condition. Such a boundary condition cannot simulate the cold wake associated with a tropical cyclone, which arises due to the enhanced vertical mixing and entrainment below the oceanic mixed layer. This cold wake has potential implications for the intensity of the tropical cyclone itself, because it can act as a negative air-sea feedback and lead to a weakening of the storm. Therefore, proper representation of this air-sea feedback is important when assessing the sensitivity of tropical cyclone frequency and intensity to climate change. We address this issue using a coupled regional climate model, where a regional atmospheric model is coupled to a regional ocean model. The model domain encompasses the Atlantic Ocean and adjoining continental regions. The atmospheric component is the NCAR WRF model running at 30 km horizontal resolution. The oceanic component is the Regional Ocean Modeling System (ROMS) running at 0.25 degree resolution. The atmospheric and oceanic models exchange fluxes of momentum, heat, and freshwater. The control coupled integration using this model simulates fairly realistic tropical variability, including a number of hurricane-like tropical vortices. To assess the sensitivity of tropical cyclone activity to air-sea coupling, we have also carried out a companion uncoupled integration, where the time-evolving sea surface temperature from the control coupled integration is used as the lower boundary condition for the uncoupled atmospheric model. We analyze the frequency and intensity of the tropical cyclones, as well as the associated precipitation, in both the coupled and the uncoupled integrations. Preliminary results indicate that air-sea feedbacks can have a significant impact on tropical cyclone activity.

Hsieh, J.; Li, M.; Saravanan, R.; Chang, P.

2009-12-01

364

Sensitivity of physical parameterizations on prediction of tropical cyclone Nargis over the Bay of Bengal using WRF model  

NASA Astrophysics Data System (ADS)

Comprehensive sensitivity analyses on physical parameterization schemes of Weather Research Forecast (WRF-ARW core) model have been carried out for the prediction of track and intensity of tropical cyclones by taking the example of cyclone Nargis, which formed over the Bay of Bengal and hit Myanmar on 02 May 2008, causing widespread damages in terms of human and economic losses. The model performances are also evaluated with different initial conditions of 12 h intervals starting from the cyclogenesis to the near landfall time. The initial and boundary conditions for all the model simulations are drawn from the global operational analysis and forecast products of National Center for Environmental Prediction (NCEP-GFS) available for the public at 1° lon/lat resolution. The results of the sensitivity analyses indicate that a combination of non-local parabolic type exchange coefficient PBL scheme of Yonsei University (YSU), deep and shallow convection scheme with mass flux approach for cumulus parameterization (Kain-Fritsch), and NCEP operational cloud microphysics scheme with diagnostic mixed phase processes (Ferrier), predicts better track and intensity as compared against the Joint Typhoon Warning Center (JTWC) estimates. Further, the final choice of the physical parameterization schemes selected from the above sensitivity experiments is used for model integration with different initial conditions. The results reveal that the cyclone track, intensity and time of landfall are well simulated by the model with an average intensity error of about 8 hPa, maximum wind error of 12 m s-1and track error of 77 km. The simulations also show that the landfall time error and intensity error are decreasing with delayed initial condition, suggesting that the model forecast is more dependable when the cyclone approaches the coast. The distribution and intensity of rainfall are also well simulated by the model and comparable with the TRMM estimates.

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

2011-09-01

365

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

NASA Technical Reports Server (NTRS)

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).

Yonekura, Emmi; Hall, Timothy M.

2011-01-01

366

Relationships Between Basin-Wide and Landfalling Atlantic Tropical Cyclones: Comparing Long-Term Simulations with Paleoevidence (Invited)  

NASA Astrophysics Data System (ADS)

Substantial uncertainties exist regarding the long-term relationships between various measures of Atlantic Tropical Cyclone (TC) activity, e.g. annual total named storm counts vs. major landfalling U.S. hurricanes. Evaluating relationships from historical observations is perilous, as the records are short, spanning little more than a century, and observational biases potentially become quite substantial in earlier decades. Comparisons are further hampered by the fact that these biases may have differential impacts on different quantities. Here, we instead examine the relationships between various measures of Atlantic TC activity using the idealized framework provided by a climate model simulation subject to estimated natural and anthropogenic radiative forcing over the past millennium (AD 850-1999). Following the downscaling approach of Emanuel et al, we use the large-scale fields of the climate model simulation to force a model of tropical cyclone genesis, tracking, and intensification. This process yields synthetic long-term basin-wide seasonal TC histories with realistic statistical attributes. Using the simulated TC histories, we examine relationships between basin-wide TC activity, landfalling TCs, hurricanes, landfalling hurricanes, and major U.S. landfalling hurricanes on timescales ranging from the interannual through centennial. We also use these synthetic TC histories to assess the limitations of inferences that can be drawn from networks of geological records of past landfalling hurricanes.

Mann, M. E.; Kozar, M. E.; Emanuel, K.

2013-12-01

367

Using WWLLN and TRMM data to investigate lightning activity and convective parameters in 2005 - 2010 tropical cyclones  

NASA Astrophysics Data System (ADS)

The main objective of this research is to investigate the relationship between lightning activity in the inner core, intensity changes, and convective parameters in all tropical cyclones (TCs) that occurred between 2005 and 2010. The World Wide Lightning Location Network (WWLLN), a real-time network that covers the entire globe, is used to observe lightning activity during the evolution of TCs. The TCs intensification processes are quantified in terms of pressure and/or horizontal winds. Special attention is given to lightning activity accompanying intensity changes, since several previous works have identified peaks in lightning count in the inner core during intensification and weakening processes. The convective parameters are obtained from TRMM (Tropical Rainfall Measuring Mission) passive microwave radar data in the 37- and 85-GHz channels and TRMM-derived products (e.g., cloud liquid water, precipitable water, cloud ice, and precipitable ice). Several case studies are presented, including Cyclone Nargis in the North Indian Ocean, TCs near the Australian coast, and five intense Western North Pacific typhoons. Preliminary results indicate that lightning activity pinpoints the active convection areas in TCs, especially during intensity changes.

Solorzano, N. N.; Thomas, J. N.; Holzworth, R. H.

2010-12-01

368

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

NASA Astrophysics Data System (ADS)

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.

Cai, Ninghao; Xu, Xin; Song, Lili; Bai, Lina; Ming, Jie; Wang, Yuan

2014-02-01

369

Physically-based Assessment of Tropical Cyclone Damage and Economic Losses  

NASA Astrophysics Data System (ADS)

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.

Lin, N.

2012-12-01

370

Sensitivities of Modeled Tropical Cyclones to Surface Friction and the Coriolis Parameter  

NASA Technical Reports Server (NTRS)

In this investigation the sensitivities of a 2-D tropical cyclone (TC) model to surface frictional coefficient and the Coriolis parameter are studied and their implication is discussed. The model used is an axisymmetric version of the latest version of the Goddard cloud ensemble model. The model has stretched vertical grids with 33 levels varying from 30 m near the bottom to 1140 m near the top. The vertical domain is about 21 km. The horizontal domain covers a radius of 962 km (770 grids) with a grid size of 1.25 km. The time step is 10 seconds. An open lateral boundary condition is used. The sea surface temperature is specified at 29C. Unless specified otherwise, the Coriolis parameter is set at its value at 15 deg N. The Newtonian cooling is used with a time scale of 12 hours. The reference vertical temperature profile used in the Newtonian cooling is that of Jordan. The Newtonian cooling models not only the effect of radiative processes but also the effect of processes with scale larger than that of TC. Our experiments showed that if the Newtonian cooling is replaced by a radiation package, the simulated TC is much weaker. The initial condition has a temperature uniform in the radial direction and its vertical profile is that of Jordan. The initial winds are a weak Rankin vortex in the tangential winds superimposed on a resting atmosphere. The initial sea level pressure is set at 1015 hPa everywhere. Since there is no surface pressure perturbation, the initial condition is not in gradient balance. This initial condition is enough to lead to cyclogenesis, but the initial stage (say, the first 24 hrs) is not considered to resemble anything observed. The control experiment reaches quasi-equilibration after about 10 days with an eye wall extending from 15 to 25 km radius, reasonable comparing with the observations. The maximum surface wind of more than 70 m/s is located at about 18 km radius. The minimum sea level pressure on day 10 is about 886 hPa. Thus the overall simulation is considered successful and the model is considered adequate for our investigation.

Chao, Winston C.; Chen, Baode; Tao, Wei-Kuo; Lau, William K. M. (Technical Monitor)

2002-01-01

371

Cyclone Susan  

NSDL National Science Digital Library

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.

Shirah, Greg; Maher, Steve; Kummerow, Chris

1999-01-21

372

Change of Tropical Cyclone and Seasonal Climate State in a Global Warming Experiment with a Global Cloud-System-Resolving Model  

Microsoft Academic Search

\\u000a Recent increase in computation power allows a use of high-resolution global model to investigate possible future change of\\u000a tropical cyclones. In this chapter, we propose a new approach here to pursue the issue: the use of global cloud- system resolving\\u000a model (GCRM).1 It is the model designed with the clear aim of resolving cloud cluster, an essential component of tropical

Kazuyoshi Oouchi; Masaki Satoh; Yohei Yamada; Hirofumi Tomita; Wataru Yanase

373

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 137: 18411855, October 2011 A An investigation of rotational influences on tropical-cyclone size  

E-print Network

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 137: 1841­1855, October 2011 A An investigation of rotational influences on tropical-cyclone size and intensity Roger K is offered for these findings. Copyright c 2011 Royal Meteorological Society Key Words: hurricane; typhoon

Smith, Roger K.

374

Although tropical cyclones are still not fully understood, Professor Nick Shay was responsible for uncovering the role of the deep ocean on their possible intensification. Here, he  

E-print Network

and waves over the coastal ocean to as far as 200 km offshore. These measurements are useful to improve. This is indeed a global problem as the oceans cover 71 per cent of the surface and tropical cyclones form over for uncovering the role of the deep ocean on their possible intensification. Here, he explains how his current

Miami, University of

375

Impacts of AirSea Interaction on Tropical Cyclone Track and Intensity Goddard Earth and Technology Center, University of Maryland, Baltimore County, Baltimore, and Laboratory for Atmospheres,  

E-print Network

is negative in the rear and positive in the front of a TC in the coupled experiments, the enhanced diabaticImpacts of Air­Sea Interaction on Tropical Cyclone Track and Intensity LIGUANG WU Goddard Earth and Technology Center, University of Maryland, Baltimore County, Baltimore, and Laboratory for Atmospheres, NASA

Wang, Bin

376

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

377

An assessment of the ECMWF tropical cyclone ensemble forecasting system and its use for insurance loss predictions  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TC) are amongst the most impressive and destructive weather systems of Earth's atmosphere. The costs related to such intense natural disasters have been rising in recent years and may potentially continue to increase in the near future due to changes in magnitude, timing, duration or location of tropical storms. This is a challenging situation for numerical weather prediction, which should provide a decision basis for short term protective measures through high quality medium range forecasts on the one hand. On the other hand, the insurance system bears great responsibility in elaborating proactive plans in order to face these extreme events that individuals cannot manage independently. Real-time prediction and early warning systems are needed in the insurance sector in order to face an imminent hazard and minimise losses. Early loss estimates are important in order to allocate capital and to communicate to investors. The ECMWF TC identification algorithm delivers information on the track and intensity of storms based on the ensemble forecasting system. This provides a physically based framework to assess the uncertainty in the forecast of a specific event. The performance of the ECMWF TC ensemble forecasts is evaluated in terms of cyclone intensity and location in this study and the value of such a physically-based quantification of uncertainty in the meteorological forecast for the estimation of insurance losses is assessed. An evaluation of track and intensity forecasts of hurricanes in the North Atlantic during the years 2005 to 2009 is carried out. Various effects are studied like the differences in forecasts over land or sea, as well as links between storm intensity and forecast error statistics. The value of the ECMWF TC forecasting system for the global re-insurer Swiss Re was assessed by performing insurance loss predictions using their in-house loss model for several case studies of particularly devastating events. The generally known problem of the intensity bias in tropical cyclone forecasts is a very critical aspect, when using the meteorological forecasts for insurance loss prediction in such a chain modelling approach.

Aemisegger, F.; Martius, O.; Wüest, M.

2010-09-01

378

Tropical Cyclone Track Convergence Patterns, Arctic Sea-Ice Loss, and Superstorm Sandy: Is There a Connection?  

NASA Astrophysics Data System (ADS)

The potential for disruption to populations and food production due to global climate change will be catastrophic in some regions. Among the most vulnerable regions are those impacted by intensifying or changing tropical cyclones (TC). The objective of this research is to identify historical trends in TC tracks and regional circulation patterns that may forecast increasing risks due to TC intensification under global climate warming. We carry out spatial and temporal analysis of the 1979 - 2011 International Best Track Archive for Climate Stewardship (IBTrACS) historical hurricane database. The data were divided into several subsets to allow analysis of trend in: (i) early (JJAS) and late (OND) seasonal trends; and (ii) multi-year intervals (1979-95 and 1996-2011) to differentiate possible long term trends, if any. Geographical Information Systems (GIS) overlay analysis of the IBTrACS 64 knot hurricane wind radii data identified varying levels of historical tropical cyclone track convergence in the North Atlantic (NA) basin. Results of the track convergence analysis provide a first order analysis regarding changing potential population vulnerabilities due to changing seasonal or long-term tropical cyclone activity. During the summer of 2012, the amount of sea ice on the Arctic Ocean was diminished to about half of its normal extent and 25% of its normal volume relative to the nearly steady conditions that existed before the 1980s. This record loss continues an inexorable decline observed during recent decades. The dramatic increase in open water allows much more solar energy absorption at high latitude. Most of this extra heat returns to the atmosphere in autumn, contributing to the Arctic's rate of warming; exceeding that of mid-latitudes by a factor of two to three, a phenomenon called Arctic Amplification (AA). During October 2012, prior to the arrival of Superstorm Sandy along the eastern seaboard, AA was particularly strong, resulting in a substantial weakening of the poleward temperature gradient in the northern hemisphere. Evidence will be presented suggesting that the anomalous Arctic warming following record sea-ice losses in summer 2012 contributed to the formation of the strong and persistent high-pressure blocking pattern that set up a steep pressure gradient from the mid-Atlantic to Nova Scotia. The result was the diversion of Sandy from the typical NE AB path to an unprecedented westward collision with the coast of New Jersey. The critical question now is whether the storm track intensification trend in recent years will combine with a consistent NA blocking high in fall to increase TC threats to the US northeast and Canadian maritime provinces?

Barnes, C. C.; Francis, J. A.; Byrne, J. M.; Graham, J. R.; McDaniel, S. A.

2013-12-01

379

A new GNSS technique for detecting and analyzing convective systems and tropical cyclones  

NASA Astrophysics Data System (ADS)

Deep convective systems play a fundamental role in atmospheric circulation and climate. Convective Systems (CS) and Tropical Cyclones (TC) stro