These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

2

Tropical Cyclones John, Steve  

E-print Network

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

Greenslade, Diana

3

Equilibrium Tropical Cyclone Size in an Idealized State of Axisymmetric RadiativeConvective Equilibrium*  

E-print Network

Tropical cyclone size remains an unsolved problem in tropical meteorology, yet size plays a significant role in modulating damage. This work employs the Bryan cloud model (CM1) to systematically explore the sensitivity of ...

Chavas, Daniel R.

4

Idealized Study of the Ocean Impact on Coupled Tropical Cyclone Intensity Forecasts  

NASA Astrophysics Data System (ADS)

Idealized coupled hurricane forecast experiments are conducted to isolate the impact of the ocean on intensity forecasts. By nesting an initial idealized vortex into a horizontally uniform atmosphere, the influence of large-scale atmospheric processes such as wind shear and dry air entrainment on intensity evolution is minimized, allowing the oceanic influence to dominate. A one-dimensional ocean model is embedded in version 3.2 of the HWRF atmospheric model which is run over a 27-km parent domain with two (9 km and 3km) movable nests. The initial ocean is horizontally uniform, no land is present, and westward storm translation speed is accounted for by bodily advecting the ocean fields to the east. This simple setup forecasts the ocean cold wake with sufficient realism to perform idealized experiments. Experiments are run to determine the impact of available ocean thermal energy (represented by Tropical Cyclone Heat Potential, or TCHP), storm translation speed, and storm size. In all experiments, maximum intensity is reached after ~30 h and displays strong sensitivity to TCHP and comparatively weak sensitivity to translation speed. Small storms are less sensitive to the ocean, particularly for TCHP > 75 kJ/cm2. Analysis of the temporal evolution of enthalpy flux as a function of radius from storm center demonstrates the expected reduction of enthalpy flux associated with the increased SST cooling over low TCHP regions. However, the flux reduction caused by SST cooling alone is reduced by ~40% because of adjustments in T10 and q10, demonstrating the importance of coupled atmosphere-ocean boundary layer processes for understanding the ocean impact on intensity forecasts. Atmospheric boundary layer feedback through changes in T10 and q10 also leads to an asymmetric response between storms that move from regions of high to low and regions of low to high TCHP. The enthalpy flux decrease in the former case exceeds the flux increase in the latter case by roughly a factor of two.

Halliwell, G. R.; Gopalakrishnan, S.; Marks, F.

2013-05-01

5

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

6

Tropical cyclone formation  

Microsoft Academic Search

The physics of tropical cyclone formation is not well understood, and more is known about the mature hurricane than the formative mechanisms that produce it. It is believed part of the reason for this can be traced to insufficient upper-level atmospheric data. Recent observations suggest that tropical cyclones are initiated by asymmetric interactions associated with migratory upper-level potential vorticity disturbances

Michael T. Montgomery; Brian F. Farrell

1993-01-01

7

Tropical cyclone formation  

SciTech Connect

The physics of tropical cyclone formation is not well understood, and more is known about the mature hurricane than the formative mechanisms that produce it. It is believed part of the reason for this can be traced to insufficient upper-level atmospheric data. Recent observations suggest that tropical cyclones are initiated by asymmetric interactions associated with migratory upper-level potential vorticity disturbances and low-level disturbances. Favored theories of cyclones formation, however, focus on internal processes associated with cumulus convection and/or air-sea interaction. This work focuses on external mechanisms of cyclone formation and, using both a two- and three-dimensional moist geostrophic momentum model, investigates the role of upper-level potential vorticity disturbances on the formation process. A conceptual model of tropical cyclone formation is proposed, and implications of the theory are discussed. 71 refs., 5 figs., 1 tab.

Montgomery, M.T.; Farrell, B.F. (Harvard Univ., Cambridge, MA (United States))

1993-01-15

8

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

9

Simulation of the electrification of a tropical cyclone using the WRF-ARW model: An idealized case  

NASA Astrophysics Data System (ADS)

Evolution of the electrification of an idealized tropical cyclone (TC) is simulated by using the Advanced Weather Research and Forecasting (WRF-ARW) model. The model was modified by addition of explicit electrification and a new bulk discharge scheme. The characteristics of TC lightning is further examined by analyses of the electrification and the charge structure of the TC. The findings thus obtained are able to unify most of the previous inconsisitent observational and simulation studies. The results indicate that the TC eyewall generally exhibits an inverted dipole charge structure with negative charge above the positive. In the intensification stage, however, the extremely tall towers of the eyewall may exhibit a normal tripole structure with a main negative region between two regions of positive charge. The outer spiral rainband cells display a simple normal dipole structure during all the stages. It is further found that the differences in the charge structure are associated with different updrafts and particle distributions. Weak updrafts, together with a coexistence region of different particles at lower levels in the eyewall, result in charging processes that occur mainly in the positive graupel charging zone (PGCZ). In the intensification stage, the occurrence of charging processes in both positive and negative graupel charging zones is associated with strong updraft in the extremely tall towers. In addition, the coexistence region of graupel and ice crystals is mainly situated at upper levels in the outer rainband, so the charging processes mainly occur in the negative graupel charging zone (NGCZ).

Xu, Liangtao; Zhang, Yijun; Wang, Fei; Zheng, Dong

2014-06-01

10

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

11

How Does the Eye Warm? Part I: A Potential Temperature Budget Analysis of an Idealized Tropical Cyclone  

E-print Network

How Does the Eye Warm? Part I: A Potential Temperature Budget Analysis of an Idealized Tropical In this first part of a two-part study, the mechanisms that accomplish the warming in the eye of tropical contributing to warming the eye. However, for a substantial portion of RI, the region of most rapid warming

12

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

13

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 tropical cyclones intensity. An ...

Tang, Brian Hong-An

14

Tropical cyclones and climate change  

NASA Astrophysics Data System (ADS)

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 fluctuations in the frequency and intensity of tropical cyclones greatly complicate both the detection of long-term trends and their attribution to rising levels of atmospheric greenhouse gases. Trend detection is further impeded by substantial limitations in the availability and quality of global historical records of tropical cyclones. Therefore, it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes. However, future projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2-11% by 2100. Existing modelling studies also consistently project decreases in the globally averaged frequency of tropical cyclones, by 6-34%. Balanced against this, higher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre. For all cyclone parameters, projected changes for individual basins show large variations between different modelling studies.

Knutson, Thomas R.; McBride, John L.; Chan, Johnny; Emanuel, Kerry; Holland, Greg; Landsea, Chris; Held, Isaac; Kossin, James P.; Srivastava, A. K.; Sugi, Masato

2010-03-01

15

Tropical Cyclone Report  

NSDL National Science Digital Library

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

2007-12-12

16

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.

17

Fluid Mechanics of Tropical Cyclones  

Microsoft Academic Search

: Typhoons in the northwest Pacific and hurricanes in the northeast Atlantic are particular instances of a global phenomenon\\u000a with frequently disastrous consequences known as the Tropical Cyclone (TC). This is an intense cyclone, generated over a tropical\\u000a ocean with kinetic energy 1018 J or more, which extends over several hundred kilometres and yet is above all characterized by its

1998-01-01

18

Microbarom Sources from Tropical and Extra-tropical Cyclones  

E-print Network

Microbarom Sources from Tropical and Extra-tropical Cyclones Justin E. Stopa Co with similar frequencies most commonly generated in the lee of extra-tropical and tropical cyclones. The generation of microbaroms from within a tropical cyclone is demonstrated by the use of a parametric wind

Frandsen, Jannette B.

19

Rapid Filamentation Zone in a Numerically Simulated Tropical Cyclone* YUQING WANG  

E-print Network

Rapid Filamentation Zone in a Numerically Simulated Tropical Cyclone* YUQING WANG International) outside of the primary eyewall of a tropical cyclone observed in radar images. By this mechanism, the moat to test the hypothesis in a full-physics tropical cyclone model under idealized conditions and to extend

Wang, Yuqing

20

A Ventilation Index for Tropical Cyclones  

E-print Network

An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilationor the flux of ...

Tang, Brian

21

Estimating tropical cyclone precipitation risk in Texas  

E-print Network

This paper uses a new rainfall algorithm to simulate the long-term tropical cyclone precipitation (TCP) climatology in Texas based on synthetic tropical cyclones generated from National Center for Atmospheric Research/National ...

Zhu, Laiyin

22

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

23

Tropical cyclone-ocea~ interactions Isaac Ginis  

E-print Network

I' I I I· f" I' Ii I I Tropical cyclone-ocea~ interactions Isaac Ginis Graduate School a/Oceanography, University 0/Rhode Island, USA. Abstract The advent of numerical weather prediction tropical cyclone models has demonstrably improved the forecasting of tropical cyclones during recent decades. But to establish

Rhode Island, University of

24

OCEAN RESPONSE TO TROPICAL CYCLONE Isaac Ginis  

E-print Network

Chapter 5 OCEAN RESPONSE TO TROPICAL CYCLONE Isaac Ginis fIbis chapter benefited from careful impact of sea-surface temperature (SST) on the genesis and intensification of tropical cyclones has long been recognized (Palmen 1948; Miller 1958). It is well known that tropical cyclones climatologically

Rhode Island, University of

25

Historical Global Tropical Cyclone Landfalls* JESSICA WEINKLE  

E-print Network

Historical Global Tropical Cyclone Landfalls* JESSICA WEINKLE Center for Science and Technology February 2012) ABSTRACT In recent decades, economic damage from tropical cyclones (TCs) around the world, etc.) in locations prone to tropical cyclone landfalls, rather than by changes in annual storm

Colorado at Boulder, University of

26

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; Rodrguez, Juan

2013-01-01

27

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

28

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

29

Future economic damage from tropical cyclones: sensitivities to societal and  

E-print Network

Future economic damage from tropical cyclones: sensitivities to societal and climate changes from tropical cyclones under a range of assumptions about societal change, climate change related to tropical cyclones than efforts to modulate the behaviour of storms through greenhouse gas

Colorado at Boulder, University of

30

Objective classification of historical tropical cyclone intensity  

Microsoft Academic Search

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

Michael Chenoweth

2007-01-01

31

Objective classification of historical tropical cyclone intensity  

Microsoft Academic Search

Preinstrumental records of historical tropical cyclone activity require objective methods for accurately categorizing tropical cyclone intensity. Here wind force terms and damage reports from newspaper accounts in the Lesser Antilles and Jamaica for the period 17951879 are compared with wind speed estimates calculated from barometric pressure data. A total of 95 separate barometric pressure readings and colocated simultaneous wind force

Michael Chenoweth

2007-01-01

32

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

33

Scaling of Tropical-Cyclone Dissipation  

E-print Network

The influence of climate variability and global warming on the occurrence of tropical cyclones (TC) is a controversial issue. Existing historical databases on the subject are not fully reliable, but a more fundamental hindrance is the lack of basic understanding regarding the intrinsic nature of tropical cyclone genesis and evolution. It is known that tropical cyclones involve more than a passive response to changing external forcing, but it is not clear which dynamic behaviour best describes them. Here we present a new approach based on the application of the power dissipation index (PDI), which constitutes an estimation of released energy, to individual tropical cyclones. A robust law emerges for the statistics of PDI, valid in four different ocean basins and over long time periods. In addition to suggesting a novel description of the physics of tropical cyclones in terms of critical phenomena, the law allows to quantify their response to changing climatic conditions, with an increase in the largest PDI val...

Osso, Albert; Llebot, J E

2009-01-01

34

WMO/CAS/WWW SEVENTH INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES  

E-print Network

1 WMO/CAS/WWW SEVENTH INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES Topic 2.1: Tropical-Cyclone of tropical-cyclone formation and a potentially useful perspective for forecasters and researchers. The topic of tropical cyclone formation has been the subject of considerable active research in the past four years

Smith, Roger K.

35

A Tropical Cyclone Genesis Parameter for the Tropical Atlantic  

Microsoft Academic Search

A parameter to evaluate the potential for tropical cyclone formation (genesis) in the North Atlantic between Africa and the Caribbean islands is developed. Climatologically, this region is the source of about 40% of the Atlantic basin tropical cyclones but roughly 60% of the major hurricanes. The genesis parameter is the product of appropriately scaled 5-day running mean vertical shear, vertical

Mark DeMaria; John A. Knaff; Bernadette H. Connell

2001-01-01

36

Introduction In their recent review of tropical cyclones in the  

E-print Network

Introduction Background In their recent review of tropical cyclones in the Australian region, Dare. In optimal conditions, tropical cyclones can form and then strengthen to significant intensity in as little of tropical cyclone (TC) Larry (2006) is just such an example: the cyclone that became Larry was first

Nolan, David S.

37

Raindrop Size Distribution Measurements in Tropical Cyclones  

NASA Technical Reports Server (NTRS)

Characteristics of the raindrop size distribution in seven tropical cyclones have been studied through impact-type disdrometer measurements at three different sites during the 2004-06 Atlantic hurricane seasons. One of the cyclones has been observed at two different sites. High concentrations of small and/or midsize drops were observed in the presence or absence of large drops. Even in the presence of large drops, the maximum drop diameter rarely exceeded 4 mm. These characteristics of raindrop size distribution were observed in all stages of tropical cyclones, unless the storm was in the extratropical stage where the tropical cyclone and a midlatitude frontal system had merged. The presence of relatively high concentrations of large drops in extratropical cyclones resembled the size distribution in continental thunderstorms. The integral rain parameters of drop concentration, liquid water content, and rain rate at fixed reflectivity were therefore lower in extratropical cyclones than in tropical cyclones. In tropical cyclones, at a disdrometercalculated reflectivity of 40 dBZ, the number concentration was 700 plus or minus 100 drops m(sup -3), while the liquid water content and rain rate were 0.90 plus or minus 0.05 g m(sup -3) and 18.5 plus or minus 0.5 mm h(sup -1), respectively. The mean mass diameter, on the other hand, was 1.67 plus or minus 0.3 mm. The comparison of raindrop size distributions between Atlantic tropical cyclones and storms that occurred in the central tropical Pacific island of Roi-Namur revealed that the number density is slightly shifted toward smaller drops, resulting in higher-integral rain parameters and lower mean mass and maximum drop diameters at the latter site. Considering parameterization of the raindrop size distribution in tropical cyclones, characteristics of the normalized gamma distribution parameters were examined with respect to reflectivity. The mean mass diameter increased rapidly with reflectivity, while the normalized intercept parameter had an increasing trend with reflectivity. The shape parameter, on the other hand, decreased in a reflectivity range from 10 to 20 dBZ and remained steady at higher reflectivities. Considering the repeatability of the characteristics of the raindrop size distribution, a second impact disdrometer that was located 5.3 km away from the primary site in Wallops Island, Virginia, had similar size spectra in selected tropical cyclones.

Tokay, Ali; Bashor, Paul G.; Habib, Emad; Kasparis, Takis

2008-01-01

38

Overshooting convection in tropical cyclones David M. Romps1  

E-print Network

Overshooting convection in tropical cyclones David M. Romps1 and Zhiming Kuang1 Received 20 January imagery, best-track data, and reanalysis data, tropical cyclones are shown to contain a disproportionate amount of the deepest convection in the tropics. Although tropical cyclones account for only 7

Romps, David M.

39

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

E-print Network

Extant theoretical work on the steady-state structure and intensity of idealized axisymmetric tropical cyclones relies on the assumption that isentropic surfaces in the storm outflow match those of the unperturbed environment ...

Emanuel, Kerry Andrew

40

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

41

A numerical study of the outflow layer of tropical cyclones  

NASA Technical Reports Server (NTRS)

Numerical simulations of idealized tropical cyclones with special emphasis on the outflow layer are presented. The quasi-steady state outflow layers of weak and strong cyclones are found to exhibit similar characteristics. The circulations are anticyclonic and asymmetric about the center; the outflow layer is dominated by a narrow, elongated outflow-jet contributing up to 50 percent of the angular momentum transport; the air particles in the outflow jet mostly originate from the lower level. Secondary circulations are found to influence the relative humidity and the potential vorticity at the outflow levels. In order to study the effect of upper tropospheric forcings, two variational numerical experiments using cumulus convection as the major link between the upper-level forcing and the tropical cyclone's response are conducted.

Shi, Jainn-Jong; Raman, Sethu; Chang, Simon Wei-Jen

1990-01-01

42

Mesoscale Interactions in Tropical Cyclone Genesis  

Microsoft Academic Search

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

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

1997-01-01

43

On the size distribution of Atlantic tropical cyclones  

E-print Network

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

Emanuel, Kerry Andrew

44

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

45

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

46

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 and are generally not represented properly by the subgrid-scale parameterizations in the AX configuration. The resolved eddy fluxes act to support the contraction and intensification of the maximum tangential winds. The comparisons indicate fundamental differences between convective organization in the 3-D and AX configurations for meteorologically relevant forecast time scales. While the radial and vertical gradients of the system-scale angular rotation provide a hostile environment for deep convection in the 3-D model, with a corresponding tendency to strain the convective elements in the tangential direction, deep convection in the AX model does not suffer this tendency. Also, since during the 3-D intensification process the convection has not yet organized 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 axisymmetric 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 time scales 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.

2013-05-01

47

Hurricane Isaac, August 28, 2012/NOAA Tropical Cyclones  

E-print Network

Hurricane Isaac, August 28, 2012/NOAA Tropical Cyclones A PREPAREDNESS GUIDE U.S. DEPARTMENT;2 Tropical cyclones are among nature's most powerful and destructive phenomena. If you live in an area prone to tropical cyclones, you need to be prepared. Even areas well away from the coastline can be threatened

48

WMO/CAS/WWW SIXTH INTERNATIONAL WORKSHOP on TROPICAL CYCLONES  

E-print Network

533 WMO/CAS/WWW SIXTH INTERNATIONAL WORKSHOP on TROPICAL CYCLONES Topic 5.2 : Factors Contributing.2.3 Tropical cyclone case studies a) India b) Australia c) United States 5.2.4 Differing views of the role for example. Losses from individual tropical cyclones have been catastrophic across centuries. Rappaport

Colorado at Boulder, University of

49

OBSERVATION AND TRACKING OF TROPICAL CYCLONES USING RESOLUTION ENHANCED SCATTEROMETRY  

E-print Network

OBSERVATION AND TRACKING OF TROPICAL CYCLONES USING RESOLUTION ENHANCED SCATTEROMETRY by R. Ryan AND TRACKING OF TROPICAL CYCLONES USING RESOLUTION ENHANCED SCATTEROMETRY R. Ryan Halterman Department are used, in comparison with standard L2B data product winds, to observe and track tropical cyclones

Long, David G.

50

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;2 Tropical cyclones are among nature's most powerful and destructive phenomena. If you live in an area prone to tropical cyclones, you need to be prepared. Even areas well away from the coastline can be threatened

Fang, Yuguang "Michael"

51

WMO/CAS/WWW SEVENTH INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES  

E-print Network

4.5.1 WMO/CAS/WWW SEVENTH INTERNATIONAL WORKSHOP ON TROPICAL CYCLONES 4.5: Economic Impacts of Tropical Cyclones Rapporteur: Ryan P. Crompton Risk Frontiers Macquarie University NSW, 2109 Australia risen dramatically in recent decades and tropical cyclones have contributed significantly to this trend

Colorado at Boulder, University of

52

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

E-print Network

I I Comments on "Global Climate Change and Tropical Cyclones": Part II 1 ANTHONY J. BROCCOLI of the inner core oftropical cyclones. Thus, the relevant issue is whether or not the tropical vortices and and Tropical Cyclones": Part II Manabe 1990, 1992; Wu and Lau 1992; Haarsma et I al. 1993; Bengtsson et al

Broccoli, Anthony J.

53

TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 131 (2013)  

E-print Network

TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 1­31 (2013) Meteorological Institute Ludwig Maximilians University of Munich Paradigms for tropical cyclone intensification Michael T. Montgomerya 1 and Roger K, University of Munich, Munich, Germany. Abstract: We review the four main paradigms of tropical cyclone

Smith, Roger K.

54

Environmental Factors Affecting Tropical Cyclone Power Dissipation KERRY EMANUEL  

E-print Network

Environmental Factors Affecting Tropical Cyclone Power Dissipation KERRY EMANUEL Program by tropical cyclones in the Atlantic and western North Pacific are presented. These show considerable of the three factors are quantified, and implications for future trends and variability of tropical cyclone

Emanuel, Kerry A.

55

Citizen scientists analyzing tropical cyclone intensities  

NASA Astrophysics Data System (ADS)

A new crowd sourcing project called CycloneCenter enables the public to analyze historical global tropical cyclone (TC) intensities. The primary goal of CycloneCenter, which launched in mid-September, is to resolve discrepancies in the recent global TC record arising principally from inconsistent development of tropical cyclone intensity data. The historical TC record is composed of data sets called best tracks, which contain a forecast agency's best assessment of TC tracks and intensities. Best track data have improved in quality since the beginning of the geostationary satellite era in the 1960s (because TCs could no longer disappear from sight). However, a global compilation of best track data (International Best Track Archive for Climate Stewardship (IBTrACS)) has brought to light large interagency differences between some TC best track intensities, even in the recent past [Knapp et al., 2010Knapp et al., 2010]. For example, maximum wind speed estimates for Tropical Cyclone Gay (1989) differed by as much as 70 knots as it was tracked by three different agencies.

Hennon, Christopher C.

2012-10-01

56

Objective classification of historical tropical cyclone intensity  

NASA Astrophysics Data System (ADS)

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

Chenoweth, Michael

2007-03-01

57

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

58

Environmental Control of Tropical Cyclone Intensity  

Microsoft Academic Search

The influence of various environmental factors on tropical cyclone intensity is explored using a simple coupled ocean atmosphere model. It is first demonstrated that this model is capable of accurately replicating the intensity evolution of storms that move over oceans whose upper thermal structure is not far from monthly mean climatology and that are relatively unaffected by environmental wind shear.

Kerry Emanuel; Christopher Desautels; Christopher Holloway; Robert Korty

2004-01-01

59

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

60

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

61

How Do Outer Spiral Rainbands Affect Tropical Cyclone Structure and Intensity?* YUQING WANG  

E-print Network

How Do Outer Spiral Rainbands Affect Tropical Cyclone Structure and Intensity?* YUQING WANG and intensity of tropical cyclones is studied through a series of numerical experiments using the cloud-resolving tropical cyclone model TCM4. Becausediabaticheatingdueto phasechangesis the maindrivingforce

Wang, Yuqing

62

Predictability of North Atlantic Tropical Cyclone Activity on Intraseasonal Time Scales  

E-print Network

Predictability of North Atlantic Tropical Cyclone Activity on Intraseasonal Time Scales JAMES I Recent work suggests that there may exist skill in forecasting tropical cyclones (TC) using dynamically initialization. 1. Introduction Developing skillful tropical cyclone (TC) forecasts using statistical (e

Webster, Peter J.

63

UNIVERSITY OF MIAMI VERIFICATION OF TROPICAL CYCLONE WIND RADII, INTENSITY, AND TRACK  

E-print Network

UNIVERSITY OF MIAMI VERIFICATION OF TROPICAL CYCLONE WIND May 2014 #12; 2 Verification of Tropical Cyclone Wind Radii, Intensity, and Track for tropical cyclones. Creating these forecasts involves the use of human interpretation

Miami, University of

64

Comparison and Validation of Tropical Rainfall Measuring Mission (TRMM) Rainfall Algorithms in Tropical Cyclones.  

E-print Network

?? Tropical Rainfall Measuring Mission (TRMM) rainfall retrieval algorithms are evaluated in tropical cyclones (TCs). Differences between the Precipitation Radar (PR) and TRMM Microwave Imager (more)

Zagrodnik, Joseph P

2012-01-01

65

Initial Condition Sensitivity and Dynamical Mechanisms of Perturbation Growth in Tropical Cyclones.  

E-print Network

??Studying dynamical mechanisms of perturbation growth in tropical cyclones is important from a perspective of designing ensemble prediction system and adaptive observations for tropical cyclones. (more)

Yamaguchi, Munehiko

2010-01-01

66

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

67

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

68

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

69

CYGNSS: NASA Earth Venture Tropical Cyclone Mission  

NASA Astrophysics Data System (ADS)

The NASA Earth Venture Cyclone Global Navigation Satellite System (CYGNSS) is a spaceborne mission scheduled to launch in October 2016 that is focused on tropical cyclone (TC) inner core process studies. CYGNSS attempts to resolve one of the principle deficiencies with current TC intensity forecasts, which lies in inadequate observations and modeling of the inner core. CYGNSS is specifically designed to address these two limitations by combining the all-weather performance of GNSS bistatic ocean surface scatterometry with the sampling properties of a constellation of satellites. CYGNSS measurements of bistatic radar cross section of the ocean can be directly related to the near surface wind speed, in a manner roughly analogous to that of conventional ocean wind scatterometers. The technique has been demonstrated previously from space by the UK-DMC mission in 2005-6.

Ruf, Christopher; Chang, Paul; Clarizia, Maria Paola; Jelenak, Zorana; Ridley, Aaron; Rose, Randall

2014-10-01

70

Space options for tropical cyclone hazard mitigation  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

71

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

72

19Bulletin of the American Meteorological Society Tropical Cyclones and  

E-print Network

19Bulletin of the American Meteorological Society Tropical Cyclones and Global Climate Change instrumental record makes extensive analyses of the natural variability of global tropical cyclone activities are small compared with the observed natural variations and fall within the uncertainty range in current

Emanuel, Kerry A.

73

A Climatology of the Extratropical Transition of Atlantic Tropical Cyclones  

Microsoft Academic Search

A comprehensive climatology of extratropically transitioning tropical cyclones in the Atlantic basin is pre- sented. Storm tracks and intensities over a period from 1899 to 1996 are examined. More detailed statistics are presented only for the most reliable period of record, beginning in 1950. Since 1950, 46% of Atlantic tropical cyclones transitioned to the extratropical phase. The coastal Atlantic areas

Robert E. Hart; Jenni L. Evans

2001-01-01

74

On The Genesis of Tropical Cyclones: Role of Mesoscale Interactions  

NASA Technical Reports Server (NTRS)

Before the last decades of the 20th century, observations were rarely adequate to assess the role of mesoscale circulations in the formation of tropical cyclones. Recent developments in remote-sensing technology have allowed routine collection of measurements that reveal the small- and mesoscale structure of forming tropical cyclones. Additional information is contained in the original extended abstract.

Ritchie, Elizabeth; Simpson, Joanne; Pierce, Harold; Velden, Christopher; Brueske, Kurt; Einaudi, Franco

2000-01-01

75

ERS scatterometer wind data impact on ECMWF's tropical cyclone forecasts  

Microsoft Academic Search

This paper describes the positive impact of ERS scatterometer data on tropical cyclone analyses and forecasts at the European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, U.K. ERS scatterometer data is especially valuable because sparse genesis regions of tropical cyclones are available in the data, and they are available in cloudy and rainy conditions. In November 1997, ECMWF introduced a

Lars Isaksen; A. Stoffelen

2000-01-01

76

Satellite observations of tropical cyclones during the 1990's  

NASA Technical Reports Server (NTRS)

Operational satellite advances expected in the area of tropical cyclone studies with the GOES I-M geosynchronous satellite and the polar orbiting NOAA K-M satellite are discussed. Major tropical cyclone quantities and processes and the required parameters are discussed, with emphasis on spatial and vertical resolution. The problem of insertions of satellite measurements into numerical models is addressed.

Shenk, William E.; Rodgers, Edward B.; Chang, Simon

1989-01-01

77

The environmental influence on tropical cyclone precipitation  

NASA Technical Reports Server (NTRS)

The intensity, spatial, and temporal changes in precipitation were examined in three North Atlantic hurricanes during 1989 (Dean, Gabrielle, and Hugo) using precipitation estimates made from Special Sensor Microwave/Imager (SSM/I) measurements. In addition, analyses from a barotropic hurricane forecast model and the European Centre for Medium-Range Weather Forecast model were used to examine the relationship between the evolution of the precipitation in these tropical cyclones and external forcing. The external forcing parameters examined were (1) mean climatological sea surface temperatures, (2) vertical wind shear, (3) environmental tropospheric water vapor flux, and (4) upper-tropospheric eddy relative angular momentum flux convergence. The analyses revealed that (1) the SSM/I precipitation estimates were able to delineate and monitor convective ring cycles similar to those observed with land-based and aircraft radar and in situ measurements; (2) tropical cyclone intensification was observed to occur when these convective rings propagated into the inner core of these systems (within 111 km of the center) and when the precipitation rates increased; (3) tropical cyclone weakening was observed to occur when these inner-core convective rings dissipated; (4) the inward propagation of the outer convective rings coincided with the dissipation of the inner convective rings when they came within 55 km of each other; (5) in regions with the combined warm sea surface temperatures (above 26 C) and low vertical wind shear (less than 5 m/s), convective rings outside the region of strong lower-tropospheric inertial stability could be initiated by strong surges of tropospheric moisture, while convective rings inside the region of strong lower-tropospheric inertial stability could be enhanced by upper-tropospheric eddy relative angular momentum flux convergence.

Rodgers, Edward B.; Baik, Jong-Jin; Pierce, Harold F.

1994-01-01

78

Tropical cyclone genesis products at ECMWF  

NASA Astrophysics Data System (ADS)

The operational ECMWF forecast system is nowadays able not only to analyse the current location of a tropical cyclone (TC) and predict its subsequent evolution, but also to predict the genesis of tropical cyclones, often several days before they occur. The advent of 4D-Var and assimilation of massive amounts of satellite data, combined with better model physics and an increase of horizontal/vertical resolution are among the numerous important changes made in the past with positive impact in TC forecast skill. Recent changes to the forecast system that have substantially improved the TC predictions are the increase in horizontal resolution in 2006, from T511 (40 km) to T799 (25 km) (T255 to T399 in the EPS), and improved model physics introduced in 2007. ECMWF generates a number of specific products for tropical cyclone forecasts. For each TC observed at initial time, a tracking algorithm is used to identify the successive positions of the TC throughout the forecast range. The tracker is applied to the deterministic T799 model and to each member of the EPS. The EPS tracks are used to generate strike probability maps. The tracking algorithm has recently been extended to identify and track new TCs that are predicted to appear during the forecast. Strike probability products for TC genesis have been developed and some cases will be selected to illustrate this product. Results from the objective verification package, upgraded to include the verification of TC genesis, will be presented and discussed, emphasising the impact on TC performance from recent changes in the forecast system.

Prates, F.; Vitart, Frederic

2009-09-01

79

Western North Pacific Tropical Cyclone Intensity and ENSO  

Microsoft Academic Search

The influence of the El Nio-Southern Oscillation (ENSO) on tropical cyclone intensity in the western North Pacific basin is examined. Accumulated cyclone energy (ACE), constructed from the best-track dataset for the region for the period 1950-2002, and other related variables are analyzed. ACE is positively correlated with ENSO indices. This and other statistics of the interannually varying tropical cyclone dis-

Suzana J. Camargo; Adam H. Sobel

2005-01-01

80

Investigating the surface effects of a tropical cyclone  

NASA Astrophysics Data System (ADS)

Understanding how the topmost layer of the ocean behaves during a tropical cyclone can improve forecasting and prediction of cyclone strength and intensity. Previous studies have shown that the degree of sea-air heat transfer within this turbulent layer is an important factor in the overall behavior and propagation of tropical cyclones, but because these effects are difficult to observe directly, data are relatively scarce.

Wendel, JoAnna

2014-10-01

81

A Study of Microphysical Parameterizations and Simulated Tropical Cyclone Development  

NASA Astrophysics Data System (ADS)

This presentation highlights major results from an idealized tropical cyclone case study in which the Weather Research and Forecasting (WRF) model was used to compare and evaluate three bulk microphysics parameterization (MP) schemes with various degrees of complexity: the Ferrier single-moment 3-category, the WRF single-moment 6-category (WSM6) and the Thompson double-moment 6-category formulations. We first compare the sensitivity of the WRF-simulated intensification of an idealized tropical cyclone to the three MP schemes. We then compare the heating profiles and hydrometeor distributions from the three schemes. We further diagnose the source and sink terms of all the hydrometeor budgets. Results from this diagnosis indicate that the major differences in the production of hydrometeors in these schemes are more in the spectral definition of individual hydrometeor categories and spectral-dependent microphysical processes, such as accretion growth and sedimentation, than the differences between the single- and double-moment formulations. Differences in the assumed pathways to the production of frozen hydrometeors also significantly contribute to the differences among these schemes. This study demonstrates that hydrometeor budget analysis is an effective tool for MP scheme comparison and evaluation studies, allowing better understanding of actual assumed pathways to cloud and precipitation production in these schemes and their associated uncertainties.

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

2014-05-01

82

A study of tropical cyclone influence on the generation of internal tides  

NASA Astrophysics Data System (ADS)

An investigation is made into modifications of the semidiurnal internal tide on the Western Australian Shelf by a passing tropical cyclone. Current mooring observations are presented, taken during the passage of Tropical Cyclone Bobby (1995) over these mooring locations. The observations reveal large vertical excursions at near-inertial frequency of the isotherm during and following the cyclone's passage. This coincides with diminishing semidiurnal baroclinic tides. To gain dynamical insight into the observations, a fully three-dimensional, free surface, nonlinear, hydrostatic model is applied to the Western Australian Shelf. The model is initialized with realistic stratification and forced by representative tides and cyclone winds. The wind-forcing is derived from an idealized analytical cyclone model prescribed from observed cyclone track and central pressure data, and the tidal forcing allows for the generation of internal tides. The cyclone modifies stratification by turbulent mixing, upwelling/downwelling and density advection up or down the shelf slope. This results in significant changes to internal tide characteristic paths and hence the internal tide generation process on the continental slope. Mixing is enhanced over the shelf due to shallow topography with respect to the shelf slope region creating a strong density front at the shelf edge. Observations and modeling show that the water column response to the cyclone passage is most abrupt in shallow water at 125 m, then at 300 m depth. The model reproduces the main features of the observed inertial oscillations concomitant with the dampening of M2 internal tides after the passage of the cyclone.

Davidson, Fraser J. M.; Holloway, Peter E.

2003-03-01

83

Tropical Cyclone Event Sequence Similarity Search via Dimensionality Reduction and Metric Learning  

E-print Network

Tropical Cyclone Event Sequence Similarity Search via Dimensionality Reduction and Metric Learning events (such as tropical cyclones) similarity query output. In this paper, we propose a framework cyclone events, represented by arbitrary length multidimensional spatiotemporal data sequences. A critical

Ding, Wei

84

Meteorological and Paleoclimatological Studies of Eastern Pacific Tropical Cyclones Using Oxygen and Hydrogen Isotope Ratios  

Microsoft Academic Search

The East Pacific Ocean off the coast of Mexico encompasses the most concentrated region of tropical cyclone activity on the globe. This region offers a multitude of opportunities for scientific discovery concerning the meteorological characteristics of tropical cyclones and a long-term record of tropical cyclone activity. Aircraft flights into Eastern Pacific tropical cyclones by the Hurricane Research Division of NOAA

J. R. Lawrence; F. Marks

2007-01-01

85

The Prediction of Northern Hemisphere Tropical1 Cyclones by the ECMWF Ensemble and2  

E-print Network

The Prediction of Northern Hemisphere Tropical1 Cyclones by the ECMWF Ensemble and2 Deterministic errors of Tropical Cyclones (TC), including pre- and post-TC stages are ex-13 plored in the European The Prediction of Tropical Cyclones ....3 1. Introduction34 Tropical Cyclones (TC) are among the most destructive

Hodges, Kevin

86

Sea turtle species vary in their susceptibility to tropical cyclones  

Microsoft Academic Search

Severe climatic events affect all species, but there is little quantitative knowledge of how sympatric species react to such\\u000a situations. We compared the reproductive seasonality of sea turtles that nest sympatrically with their vulnerability to tropical\\u000a cyclones (in this study, tropical cyclone refers to tropical storms and hurricanes), which are increasing in severity due\\u000a to changes in global climate. Storm

David A. Pike; John C. Stiner

2007-01-01

87

Tropical Cyclone Intensity Increase near Australia as a Result of Climate Change  

Microsoft Academic Search

Idealized tropical cyclones are inserted into a regional climate model and the resulting intensity evolution of the storms is examined under current and enhanced greenhouse climates. The regional climate model is imple- mented over a model domain near Australia. In general, storm intensities increase under enhanced greenhouse conditions, although these increases are mostly not statistically significant. The simulated intensities are

Kevin J. E. Walsh; Brian F. Ryan

2000-01-01

88

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

89

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

90

Ideals of polynomial semirings in tropical mathematics  

E-print Network

We describe the ideals, especially the prime ideals, of semirings of polynomials over layered domains, and in particular over supertropical domains. Since there are so many of them, special attention is paid to the ideals arising from layered varieties, for which we prove that every prime ideal is a consequence of finitely many binomials. We also obtain layered tropical versions of the classical Principal Ideal Theorem and Hilbert Basis Theorem.

Izhakian, Zur

2011-01-01

91

Seasonal versus permanent thermocline warming by tropical cyclones  

E-print Network

Recent studies suggest that the enhanced upper ocean mixing caused by tropical cyclones significantly contributes to the ocean heat transport. However, existing studies that try to quantify this contribution make the ...

Ferrari, Raffaele

92

Tropical Cyclone Nargis: 2008 - Duration: 0:45.  

NASA Video Gallery

This new animation, developed with the help of NASA's Pleiades supercomputer, illustrates how tropical cyclone Nargis formed in the Indian Ocean's Bay of Bengal over several days in late April 2008...

93

The effects of ocean eddies on tropical cyclones  

E-print Network

The purpose of this study is to understand the interactions of tropical cyclones with ocean eddies. In particular we examine the influence of a cold-core eddy on the cold wake formed during the passage of Typhoon Fanapi ...

Miltenberger, Alexander Reid

2012-01-01

94

The Deadliest Atlantic Tropical Cyclones, 1492-1996  

NSDL National Science Digital Library

This information updates a popular statistical summary about hurricanes that have affected the United States this century. That study, which included a tabulation of the largest US losses of life caused by those storms, had no counterpart for earlier tropical cyclones or for casualties incurred elsewhere. In this presentation that work is extended, providing a catalog of Atlantic tropical cyclones associated with loss of life during the period 1492-1994. The catalog comprises two lists. The first list (Appendix 1) provides information about tropical cyclones responsible for at least 25 deaths. The second list (Appendix 2) identifies storms associated with loss of life that, while not quantified, may have reached at least 25, according to records about those events. In addition the site includes an introduction, tropical cyclone terminology, casualty information, conclusions, acknowledgements, and references.

95

Effect of remote sea surface temperature change on tropical cyclone potential intensity  

E-print Network

LETTERS Effect of remote sea surface temperature change on tropical cyclone potential intensity Gabriel A. Vecchi1 & Brian J. Soden2 The response of tropical cyclone activity to global warming is widely environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity

96

Tropical Cyclone Trend Analysis using Enhanced Parallel Coordinates and Statistical Analytics  

E-print Network

Tropical Cyclone Trend Analysis using Enhanced Parallel Coordinates and Statistical Analytics Chad is demonstrated via detailed analysis of potential predictors for topical cyclone activity. By significantly

Swan II, J. Edward

97

Tropical cyclone intensity change. A quantitative forecasting scheme  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

98

The View from the Top: CALIOP Ice Water Content in the Uppermost Layer of Tropical Cyclones  

NASA Technical Reports Server (NTRS)

NASA's CALIPSO satellite carries both the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Imaging Infrared Radiometer (IIR). The lidar is ideally suited to viewing the very top of tropical cyclones, and the IIR provides critical optical and microphysical information. The lidar and the IIR data work together to understand storm clouds since they are perfectly co-located, and big tropical cyclones provide an excellent complex target for comparing the observations. There is a lot of information from these case studies for understanding both the observations and the tropical cyclones, and we are just beginning to scratch the surface of what can be learned. Many tropical cyclone cloud particle measurements are focused on the middle and lower regions of storms, but characterization of cyclone interaction with the lowermost stratosphere at the upper storm boundary may be important for determining the total momentum and moisture transport budget, and perhaps for predicting storm intensity as well. A surprising amount of cloud ice is to be found at the very top of these big storms.

Avery, Melody A.; Deng, Min; Garnier, Anne; Heymsfield, Andrew; Pelon, Jacques; Powell, Kathleen A.; Trepte, Charles R.; Vaughan, Mark A.; Winker, David M.; Young, Stuart

2012-01-01

99

Tropical cyclone motion and recurvature in TCM-90. Master's thesis  

SciTech Connect

Rawinsonde and satellite data collected during the Tropical Cyclone Motion (TCM90) experiment, which was conducted during the summer of 1990 in the Western North pacific, is used to examine tropical cyclone steering motion and recurvature. TCM-90 composite results are compared with those found in a composite study using twenty-one years (1957-77) of Western North Pacific rawinsonde data during the same August-September period and also for all months during this same 21-year period. Both data sets indicate that the composite deep-layer-mean (850-300 mb) winds 5-7 deg from the cyclone center provide an important component of the steering flow for tropical cyclones. However, despite the rawinsonde data enhancements of the TCM-90 experiment, data limitations prevented an accurate observation of steering flow conditions at individual time periods or for the average of only 5-10 time periods when composited together.

Fitzpatrick, M.E.

1992-01-01

100

A multitree perspective of the tree ring tropical cyclone record from longleaf pine (Pinus palustris Mill.), Big Thicket National  

E-print Network

A multitree perspective of the tree ring tropical cyclone record from longleaf pine (Pinus resolution needed to characterize extreme weather events such as tropical cyclones, their frequency whether individual trees sufficiently characterize tropical cyclone variability. Eight individual trees

Grissino-Mayer, Henri D.

101

Tropical cyclone frequencies inferred from Gray's yearly genesis parameter - validation of GCM tropical climates  

Microsoft Academic Search

The Gray yearly genesis parameter (YGP) is an empirical diagnostic tool used to infer regions in which necessary (but not sufficient) conditions exist for tropical cyclone development. This parameter is used here as a measure of the implied tropical cyclone frequency and area of occurrence in climate simulations generated by a GCM. In a simulation of the current climate, the

Brian F. Ryan; Ian G. Watterson; Jenni L. Evans

1992-01-01

102

Western North Pacific Tropical Cyclone Intensity and ENSO SUZANA J. CAMARGO  

E-print Network

Western North Pacific Tropical Cyclone Intensity and ENSO SUZANA J. CAMARGO International Research November 2004) ABSTRACT The influence of the El Niño­Southern Oscillation (ENSO) on tropical cyclone tropical cyclone dis- tribution are used to show that there is a tendency in El Niño years toward tropical

Sobel, Adam

103

Global climate change and tropical cyclones  

SciTech Connect

This paper offers an overview of the authors's studies during a specialized international symposium where they aimed at making an objective assessment of whether climate changes, consequent on an expected doubling of atmospheric CO[sub 2] in the next six or seven decades, are likely to increase significantly the frequency or intensity of tropical cyclones (TC). Out of three methodologies available for addressing the question they employ two, discarding the third for reasons set out in the appendix. In the first methodology, the authors enumerate reasons why, in tropical oceans, the increase in sea surface temperature (SST) suggested by climate change models might be expected to affect either (i) TC frequency, because a well-established set of six conditions for TC formation include a condition that SST should exceed 26[degrees]C, or (ii) TC intensity, because this is indicated by thermodynamic analysis to depend critically on the temperature at which energy transfer to air near the sea surface takes place. But careful study of both suggestions indicates that the expected effects of increased SST would be largely self-limiting (i) because the other five conditions strictly control how far the band of latitudes for TC formation can be further widened, and (ii) because intense winds at the sea surface may receive their energy input at a temperature significantly depressed by evaporation of spray, and possibly through sea surface cooling. In the second methodology, the authors study available historical records that have very large year-to-year variability in TC statistics. They find practically no consistent statistical relationships with temperature anomalies; also, a thorough analysis of how the El Nino-Southern Oscillation cycle influences the frequency and distribution of TCs shows any direct effects of local SST changes to be negligible. 28 refs., 4 figs.

Lighthill, J. (Univ. College London (United Kingdom)); Holland, G. (Bureau of Meteorology Research Center, Melbourne (Australia)); Gray, W.; Landsea, C. (Colorado State Univ., Fort Collins, CO (United States)); Craig, G. (Univ. of Reading (United Kingdom)); Evans, J. (Pennsylvania State Univ., College Park, PA (United States)); Kurihara, Yoshio (Princeton Univ., NJ (United States)); Guard, C. (Univ. of Guam, Mangilao (Guam))

1994-11-01

104

Numerical Simulation of the Life Cycle of Tropical Cyclones  

Microsoft Academic Search

The tropical cyclone is a solitary creature of the tropical oceans accompanied by violent rotating winds and torrential rain. Observational studies and diagnostic analyses leave little doubt that the energy required for driving the vortex comes from the latent heat of condensation released by tall convective clouds around the center, and that the frictionally induced inflow in the vortex plays

Katsuyuki Ooyama

1969-01-01

105

Sensitivity of tropical cyclone intensity to sea surface temperature  

Microsoft Academic Search

Increased occurrence of more intense tropical storms intruding further poleward has been foreshadowed as one of the potential consequences of global warming. This scenario is based almost entirely on the general circulation model predictions of warmer sea surface temperature (SST) with increasing levels of atmospheric CO[sub 2] and some theories of tropical cyclone intensification that support the notion of more

Jenni L. Evans

1993-01-01

106

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

107

Proxies of Tropical Cyclone Isotope Spikes in Precipitation: Landfall Site Selection  

NASA Astrophysics Data System (ADS)

The human experience of climate change is not one of gradual changes in seasonal or yearly changes in temperature or rainfall. Despite that most paleoclimatic reconstructions attempt to provide just such information. Humans experience climate change on much shorter time scales. We remember hurricanes, weeks of drought or overwhelming rainy periods. Tropical cyclones produce very low isotope ratios in both rainfall and in atmospheric water vapor. Thus, climate proxies that potentially record these low isotope ratios offer the most concrete record of climate change to which humans can relate. The oxygen isotopic composition of tropical cyclone rainfall has the potential to be recorded in fresh water carbonate fossil material, cave deposits and corals. The hydrogen isotopic composition of tropical cyclone rainfall has the potential to be recorded in tree ring cellulose and organic matter in fresh water bodies. The Class of carbonate organisms known as Ostracoda form their carapaces very rapidly. Thus fresh water ephemeral ponds in the subtropics are ideal locations for isotopic studies because they commonly are totally dry when tropical cyclones make landfall. The other proxies suffer primarily from a dilution effect. The water from tropical cyclones is mixed with pre-existing water. In cave deposits tropical cyclone rains mix with soil and ground waters. In the near shore coral environment the rain mixes with seawater. For tree rings there are three sources of water: soil water, atmospheric water vapor that exchanges with leaf water and tropical cyclone rain. In lakes because of their large size rainfall runoff mixes with ground water and preexisting water in the lake. A region that shows considerable promise is Texas / Northeast Mexico. In a study of surface waters that developed from the passage of Tropical Storm Allison (2001) in SE Texas both the pond water and Ostracoda that bloomed recorded the low oxygen isotope signal of that storm (Lawrence et al, 2008). In 2010 rain from Hurricane Alex, Tropical Depression 2 and Tropical Storm Hermine flooded ephemeral ponds in south Texas. Isotopic analysis of water and fossil Ostracoda from ephemeral ponds in south Texas is planned. Cores (50 cm in length) were taken in one of these ponds where living Ostracoda were found and collected.

Lawrence, J. R.; Maddocks, R.

2011-12-01

108

Numerical experiments on the genesis of Sharav cyclones: idealized simulations  

NASA Astrophysics Data System (ADS)

A three-level channel flow model is used to investigate the generation of Sharav cyclones in the lee of the Atlas mountains through "idealized" numerical experimentation. A typical initial state consists of a barotropic high low system, embedded in baroclinic shear flow and centered to the north of the Atlas mountains. If this "perturbation" is of sufficient strength, a cold-air outbreak occurs in the rear of the low as well as a southward excursion of the trough at upper levels. The cold air is blocked by the Atlas mountains, if the initial location of the low is chosen properly. The upper-level trough intensifies slightly when crossing the mountain range and induces then a low-level cyclone in the lee. The trough turns eastward later on and the new cyclone is staying close to this upper-level centre. A simple two-dimensional three-layer model is used to explain salient features of this type of lee cyclogenesis. Moreover, additional experiments are conducted in order to elucidate details of the cyclogenetic process.

Egger, Joseph; Alpert, Pinhas; Tafferner, Arnold; Ziv, Baruch

1995-03-01

109

Temporal clustering of tropical cyclones and its ecosystem impacts.  

PubMed

Tropical cyclones have massive economic, social, and ecological impacts, and models of their occurrence influence many planning activities from setting insurance premiums to conservation planning. Most impact models allow for geographically varying cyclone rates but assume that individual storm events occur randomly with constant rate in time. This study analyzes the statistical properties of Atlantic tropical cyclones and shows that local cyclone counts vary in time, with periods of elevated activity followed by relative quiescence. Such temporal clustering is particularly strong in the Caribbean Sea, along the coasts of Belize, Honduras, Costa Rica, Jamaica, the southwest of Haiti, and in the main hurricane development region in the North Atlantic between Africa and the Caribbean. Failing to recognize this natural nonstationarity in cyclone rates can give inaccurate impact predictions. We demonstrate this by exploring cyclone impacts on coral reefs. For a given cyclone rate, we find that clustered events have a less detrimental impact than independent random events. Predictions using a standard random hurricane model were overly pessimistic, predicting reef degradation more than a decade earlier than that expected under clustered disturbance. The presence of clustering allows coral reefs more time to recover to healthier states, but the impacts of clustering will vary from one ecosystem to another. PMID:22006300

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

2011-10-25

110

Temporal clustering of tropical cyclones and its ecosystem impacts  

PubMed Central

Tropical cyclones have massive economic, social, and ecological impacts, and models of their occurrence influence many planning activities from setting insurance premiums to conservation planning. Most impact models allow for geographically varying cyclone rates but assume that individual storm events occur randomly with constant rate in time. This study analyzes the statistical properties of Atlantic tropical cyclones and shows that local cyclone counts vary in time, with periods of elevated activity followed by relative quiescence. Such temporal clustering is particularly strong in the Caribbean Sea, along the coasts of Belize, Honduras, Costa Rica, Jamaica, the southwest of Haiti, and in the main hurricane development region in the North Atlantic between Africa and the Caribbean. Failing to recognize this natural nonstationarity in cyclone rates can give inaccurate impact predictions. We demonstrate this by exploring cyclone impacts on coral reefs. For a given cyclone rate, we find that clustered events have a less detrimental impact than independent random events. Predictions using a standard random hurricane model were overly pessimistic, predicting reef degradation more than a decade earlier than that expected under clustered disturbance. The presence of clustering allows coral reefs more time to recover to healthier states, but the impacts of clustering will vary from one ecosystem to another. PMID:22006300

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

2011-01-01

111

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

112

Assessing tropical cyclone trends in the context of potential sampling J. Fasullo1  

E-print Network

Assessing tropical cyclone trends in the context of potential sampling biases J. Fasullo1 Received] Recently observed trends in the tropical cyclone record are assessed in the context of potential sampling), Assessing tropical cyclone trends in the context of potential sampling biases, Geophys. Res. Lett., 33, L

Fasullo, John

113

Climate and Tropical Cyclone Activity: A New Model Downscaling Approach KERRY EMANUEL  

E-print Network

Climate and Tropical Cyclone Activity: A New Model Downscaling Approach KERRY EMANUEL Program to understand and predict the response of tropical cyclones to climate change, global climate models are at present too coarse to resolve tropical cyclones to the extent necessary to simulate their intensity

Emanuel, Kerry A.

114

Midlevel Ventilation's Constraint on Tropical Cyclone Intensity BRIAN TANG AND KERRY EMANUEL  

E-print Network

Midlevel Ventilation's Constraint on Tropical Cyclone Intensity BRIAN TANG AND KERRY EMANUEL ventilation, or the flux of low-entropy air into the inner core of a tropical cyclone (TC), is a hy to assess how ventilation affects tropical cyclone intensity via two possible pathways: the first through

Emanuel, Kerry A.

115

Effects of Vertical Wind Shear on the Predictability of Tropical Cyclones FUQING ZHANG AND DANDAN TAO  

E-print Network

Effects of Vertical Wind Shear on the Predictability of Tropical Cyclones FUQING ZHANG AND DANDAN of tropical cyclone (TC) intensity during different stages of the TC life cycle. A series of ensemble of tropical cyclones, especially during the formation and rapid intensification stage. The larger the vertical

116

Sensitivity of an Ocean-Atmosphere Coupled Model to the Coupling Method : Study of Tropical Cyclone  

E-print Network

Sensitivity of an Ocean-Atmosphere Coupled Model to the Coupling Method : Study of Tropical Cyclone) in a realistic configuration aiming at simulating the genesis and propagation of tropical cyclone Erica energetic and complex phenomena like tropical cyclones, eastern boundary upwellings (e.g. Bao et al., 2000

Recanati, Catherine

117

Sensitivity of Ocean-Atmosphere Coupled Models to the Coupling Method : Example of Tropical Cyclone  

E-print Network

Sensitivity of Ocean-Atmosphere Coupled Models to the Coupling Method : Example of Tropical Cyclone and propagation of tropical cyclone Erica. Sensitiv- ity tests to the coupling method are carried out-way coupling is essential for analyzing energetic and complex phenomena like tropical cyclones (e.g. Bao et al

118

Numerical simulations of tropical cyclone-ocean interaction with a high-resolution coupled model  

Microsoft Academic Search

The tropical cyclone-ocean interaction was investigated using a high-resolution tropical cyclone ocean coupled model. The model design consisted of the NOAA Geophysical Fluid Dynamics Laboratory tropical cyclone prediction model which was coupled with a multilayer primitive equation ocean model. Coupling between the hurricane and the ocean models was carried out by passing into the ocean model the wind stress, heat,

Morris A. Bender; Isaac Ginis; Yoshio Kurihara

1993-01-01

119

Tropical cyclone morphology from spaceborne synthetic aperture radar1 Xiaofeng Li1  

E-print Network

1 Tropical cyclone morphology from spaceborne synthetic aperture radar1 2 Xiaofeng Li1 , Jun A and innovative mapping approaches to better understand the dynamics4 of tropical cyclone genesis, morphology and movement. Although tropical cyclones can be5 detected by many remote sensors, SAR can yield high

Long, David G.

120

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

E-print Network

Mesoscale Simulation of Tropical Cyclones in the South Pacific: Climatology and Interannual Research and Forecast model at 1/38 resolution is used to simulate the statistics of tropical cyclone (TC is shown to reproduce a wide range of mesoscale convective systems. Tropical cyclones grow from the most

121

Pelagic and coastal sources of P wave microseisms: Generation under tropical cyclones  

E-print Network

Pelagic and coastal sources of P wave microseisms: Generation under tropical cyclones Jian Zhang,1 wave wave interactions due to tropical cyclones and to image Earth structure using ambient seismic wave microseisms: Generation under tropical cyclones, Geophys. Res. Lett., 37, L15301, doi:10

Gerstoft, Peter

122

The Madden-Julian Oscillation, Barotropic Dynamics, and North Pacific Tropical Cyclone Formation.  

E-print Network

The Madden-Julian Oscillation, Barotropic Dynamics, and North Pacific Tropical Cyclone Formation convection into tropical cyclones. The structure and barotropic energetics of the wave activity are similar. Liebmann et al.(1994) showed a similar modulation of tropical cyclones by the MJO in the western Pacific

Maloney, Eric

123

On Sea Surface Roughness Parameterization and Its Effect on Tropical Cyclone Structure and Intensity  

E-print Network

On Sea Surface Roughness Parameterization and Its Effect on Tropical Cyclone Structure regimes including high winds under tropical cyclone (TC) conditions, is constructed based on measurements of tropical cyclones is evaluated using TCM4. The results show that the final intensity is increased by 10

Wang, Yuqing

124

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

E-print Network

Self-Stratification of Tropical Cyclone Outflow. Part II: Implications for Storm Intensification in tropical cyclones remains poorly understood. In particular, the spatial relationship between surface fluxes; this in turn leads to predictions of vortex structure and in- tensity that agree well with tropical cyclones

Rothman, Daniel

125

An empirical framework for tropical cyclone climatology Nam-Young Kang James B. Elsner  

E-print Network

An empirical framework for tropical cyclone climatology Nam-Young Kang · James B. Elsner Received Abstract An empirical approach for analyzing tropical cyclone climate is presented. The approach uses with the opponent variations of fre- quency and intensity configure a framework for evaluating tropical cyclone

Elsner, James B.

126

Extended Prediction of North Indian Ocean Tropical Cyclones using the ECMWF Variable Ensemble Prediction System  

E-print Network

Extended Prediction of North Indian Ocean Tropical Cyclones using the ECMWF Variable Ensemble Ensemble Prediction System (VarEPS) for tropical cyclones (TCs) in the3 North Indian Ocean including: tropical cyclone genesis, pre-genesis and post-genesis track and4 intensity projections, and regional

Webster, Peter J.

127

Notes and Correspondence Are Tropical Cyclones Less Effectively Formed by Easterly Waves in the  

E-print Network

Notes and Correspondence Are Tropical Cyclones Less Effectively Formed by Easterly Waves@iastate.edu #12;1 Abstract It has been observed that the percentage of tropical cyclones originating from easterly tropical cyclones in the western North Pacific. By carefully separating easterly waves from the lower

Chen, Tsing-Chang "Mike"

128

Training on Eastern Pacific tropical cyclones for Latin American students  

NASA Astrophysics Data System (ADS)

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

Farfn, L. M.; Raga, G. B.

2009-05-01

129

Gravity waves generated by a tropical cyclone during the STEP tropical field program: A case study  

Microsoft Academic Search

Overflights of a tropical cyclone during the Australian winter monsoon field experiment of the Stratosphere-Troposphere Exchange Project (STEP) show the presence of two mesoscale phenomena: a vertically propagating gravity wave with a horizontal wavelength of about 110 km and a feature with a horizontal scale comparable to that of the cyclone's entire cloud shield (wavelength of 250 km or greater).

L. Pfister; K. R. Chan; P. P. Bui; S. Bowen; M. Legg; B. Gary; K. Kelly; M. Proffitt; W. Starr

1993-01-01

130

Tropopause adjustment to tropical cyclones as inferred from satellite ozone observations  

NASA Technical Reports Server (NTRS)

Data from the Total Ozone Mapping Spectrometer on the Nimbus-7 are used to map the climatological total ozone within and around tropical cyclones. A tropical cyclone numerical model is used to interpret total ozone patterns. The total ozone maps are used to diagnose storm intensity and to differentiate between intesifying and weakening tropical cyclones. The tropical cyclone intensity versus total ozone anomaly distribution is examined and examples of mapping the total ozone of tropical cyclones in the period 1979-1982 are presented.

Rodgers, Edward B.; Stout, John; Steranka, Joseph; Chang, Simon

1988-01-01

131

3574 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 46, NO. 11, NOVEMBER 2008 Objective Measures of Tropical Cyclone Structure  

E-print Network

Measures of Tropical Cyclone Structure and Intensity Change From Remotely Sensed Infrared Image Data Miguel in tropical cyclones from satellite infrared images is described. As the tropical cyclone develops from of cloud organization of the tropical cyclone. The results presented show that the tech- nique provides

Ritchie, Elizabeth

132

Extended Predictions of North Indian Ocean Tropical Cyclones James I. Belanger*, Peter J. Webster, and Judith A. Curry  

E-print Network

Extended Predictions of North Indian Ocean Tropical Cyclones James I. Belanger*, Peter J. WebsterEPS) for tropical cyclones (TCs) in the3 North Indian Ocean (NIO) including: tropical cyclone genesis, pre-genesis and post-genesis track4 and intensity projections, and regional outlooks of tropical cyclone activity

Webster, Peter J.

133

Modeled sensitivity of upper thermocline properties to tropical cyclone winds and possible feedbacks on the Hadley circulation  

Microsoft Academic Search

The sensitivity of upper thermocline properties, and global climate, to tropical cyclone (TC) winds is examined using global ocean and atmosphere general circulation models. We combine seven years of global, satellite-based TC wind records with a standard surface wind input data set derived from reanalysis, and we apply idealized factors to TC winds in order to model the ocean's equilibrium

Ryan L. Sriver; Matthew Huber

2010-01-01

134

Observation of tropical cyclones by high resolution scatterometry  

Microsoft Academic Search

Unprecedented views of surface wind fields in tropical cyclones (hereafter TCs) are provided by the European Remote Sensing Satellite (ERS) C band scatterometer. Scatterometer measurements at C band are able to penetrate convective storms clouds, observing the surface wind fields with good accuracy. However the resolution of the measurements (5050km2) limits the interpretation of the scatterometer signals in such mesoscale

Y. Quilfen; B. Chapron; T. Elfouhaily; K. Katsaros; J. Tournadre

1998-01-01

135

Some Aspects of Vortex Structure Related to Tropical Cyclone Motion  

Microsoft Academic Search

Some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent, barotropic numerical model with no basic current. As suggested earlier by DeMaria, the initial maximum wind speed has little effect on the track. Vortex translation associated with the beta effect depends sensitively on the strength of the flow between 300 and 1000 km from the

Michael Fiorino; Russell L. Elsberry

1989-01-01

136

A QuikSCAT climatology of tropical cyclone size  

E-print Network

QuikSCAT data of near-surface wind vectors for the years 19992008 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

137

MEDICANES: QUASI-TROPICAL MESOSCALE CYCLONES IN THE MEDITERRANEAN  

E-print Network

MEDICANES: QUASI-TROPICAL MESOSCALE CYCLONES IN THE MEDITERRANEAN Climent RAMIS1 , María TOUS1 (diameter up to 300 km) that form over the Mediterranean have been called medicanes. The cloud structures but not of the topography on the path and intensification of medicanes. The latent heat release in convective clouds

Romero, Romu

138

Tropical Cyclone Track Forecasts Using an Ensemble of Dynamical Models  

Microsoft Academic Search

The relative independence of the tropical cyclone track forecasts produced by regional and global numerical weather prediction models suggests that a simple ensemble average or consensus forecast derived from a com- bination of these models may be more accurate, on average, than the forecasts of the individual models. Forecast errors of a simple ensemble average of three models for the

James S. Goerss

2000-01-01

139

Atlantic Sea Surface Temperatures and Tropical Cyclone Formation  

Microsoft Academic Search

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

Lloyd J. Shapiro; Stanley B. Goldenberg

1998-01-01

140

Reliability of a jacket structure in a tropical cyclone environment  

SciTech Connect

The annual probability of failure due to extreme storm loading is calculated for a manned production platform installed about ten years ago in a tropical cyclone environment. Statistics of extreme loads are generated from a hindcast study using a random storm method. This method was originally developed for winter storms and has been extended, here, to treat tropical cyclones. Non-linear pushover analysis is used to evaluate the ultimate strength of the structure. The likelihood of structural failure is determined as the probability that the load vector will extend beyond the failure surface of the structure. The results indicate adequate reliability. The study highlights some features of this tropical cyclone environment and compares and contrasts them with the North Sea which is dominated by winter storms. An important element of the conventional practice outside US waters has been to use as a design condition separate extrapolations of 100 year wind, 100 year wave and 100 year current. It is demonstrated that conventional practice has resulted in significantly overdesigned structures in winter storm environments such as the North Sea. However, for tropical cyclone environments, it has produced structures of sufficient reliability but with relatively little overdesign.

Vanderschuren, L.; Efthymiou, M.; Tromans, P.S.; Graaf, J.W. van de

1996-12-31

141

Effects of Sea Spray on Tropical Cyclone Intensity  

Microsoft Academic Search

The intensity of tropical cyclones is sensitive to the rates at which enthalpy and momentum are transferred between sea and air in the high-wind core of the storm. Present models of the wind dependence of these transfer rates suggest that the effective drag coefficient is more than twice the effective enthalpy transfer coefficient at wind speeds above 25 m s21.

Edgar L Andreas; Kerry A. Emanuel

2001-01-01

142

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

143

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

144

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

145

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 Nio-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 Nia events are associated with enhanced tropical cyclone activity in the eastern Indian Ocean (2 clusters) and Coral Sea (1 cluster), while El Nio 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

146

The Looping Motion and the Asymmetry of Tropical Cyclone  

Microsoft Academic Search

We study the looping motion of tropical cyclone by a numerical simulation for the case of no steering current in order to investigate the relation between the asymmetry and the motion of model vortex. The dynamically balanced vortex is used initially to avoid an initial unrealistic motion of the vortex. The mean winds in each pressure level rotate counterclockwise in

Shigeo Abe

1987-01-01

147

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

148

In-Situ Observations in Tropical Cyclones from Ocean Drifters  

NASA Astrophysics Data System (ADS)

Ocean Drifters are cost effective, robust and high-quality instruments currently used to observe important variables in the ocean and atmosphere boundary layers during tropical cyclones. They have been configured to measure sea level atmospheric air pressure, wind velocity, solar insolation, sea surface and sub-surface temperature, ocean mixed-layer currents and three-dimensional ocean velocity (typically in depths of 0-150m). Ocean drifters have been successfully deployed in seven hurricanes (Atlantic Ocean) and in four typhoons (Pacific Ocean). Drifters are air-deployed about 18-24 hours ahead of an approaching tropical cyclone from a C-130J aircraft by the 53rd WRS "Hurricane Hunters" at a spacing of 30-50km in a line perpendicular to the expected storm track. On average, the tropical cyclone center has passed within 20km of the nearest drifter, and as close as 3km. Measurements are taken every 15 minutes and are transmitted via Argos or Iridium satellites in real-time and posted to the Global Telecommunication System of the World Weather Watch. The instrument success rate has been 92% in all previous deployments during tropical cyclone conditions from Cat-1 to Cat-5. The high quality of drifter observations has been validated with co-located measurements from dropwindsondes, nearby ocean profiling floats and satellites. Distinct features of the coupled tropical cyclone atmosphere-ocean system observed by the drifters include: the exponential decrease of sea level pressure towards the minimum at the storm center, the radius of maximum winds and their strength, the cold ocean wake on the right hand side of the storm, the inertial currents in the upper ocean, the downward propagation of inertial waves in the ocean, the relatively fast recovery of the sea surface temperature in the cold wake and the longer endurance of the sub-surface wake. In addition, the drifters have detected the response of the atmospheric boundary layer to the ocean's cold wake by measuring the distinct turning of surface winds towards the center of the tropical cyclone above the cold wake. Drifter data are a valuable asset for real-time storm assessment by warning centers, for initializing and constraining forecast models and for post-season validation/calibration of coupled models. The drifter deployment methodology will be reviewed and a summary of the observations obtained within some particularly significant tropical cyclones will be presented.

Morzel, J.; Centurioni, L. R.

2013-05-01

149

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

150

Estimating Tropical Cyclone Intensity from Infrared Image Data MIGUEL F. PIN~ EROS  

E-print Network

Estimating Tropical Cyclone Intensity from Infrared Image Data MIGUEL F. PIN~ EROS College the intensity of tropical cyclones from satellite infrared imagery in the North Atlantic Ocean basin cyclone as an indirect measurement of its maximum wind speed. The final maximum wind speed calculated

Ritchie, Elizabeth

151

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; Cyclones. Introduction A presidential declaration of a major disaster or emergency is the key action

Colorado at Boulder, University of

152

LETTER doi:10.1038/nature10552 Arabian Sea tropical cyclones intensified by  

E-print Network

LETTER doi:10.1038/nature10552 Arabian Sea tropical cyclones intensified by emissions of black developmentof tropical cyclones1 , but the atmospheric monsoon circulation and associated strong vertical wind shear limits cyclone development and intensi- fication, only permitting a pre-monsoon and post

Kossin, James P.

153

Helical organization of tropical cyclones G V Levina1,2  

E-print Network

Helical organization of tropical cyclones G V Levina1,2 1 Institute of Continuous Media Mechanics cyclone and offer a quantitative analysis for early stages in evolution of large-scale helical vortex of the vortex system during tropical cyclone formation. Based on these results, a new perspective on the role

154

Spatial distributions of tropical cyclones and gravity anomalies  

NASA Astrophysics Data System (ADS)

Spatial distributions of the beginnings and most intense stages of tropical cyclones (TCs) in the northwestern part of the Pacific Ocean are compared with gravity anomalies (GAs) in the zone of action of cyclones. The possible influence of GAs on hurricanes that reached land in the Gulf of Mexico region and in the southeastern part of China is considered. The relation of the formal feedback between some characteristics of the intensity of TCs and spatially averaged GAs is shown. It is suggested that GAs can be regarded as a factor affecting the life cycle of a TC to a certain extent.

Yaroshevich, M. I.

2013-05-01

155

The Role of Tropical Cyclones in the Formation of Tropical Upper-Tropospheric Troughs  

Microsoft Academic Search

Tropical upper-tropospheric troughs (TUTTs), also known as midoceanic troughs, are elongated troughs that appear in summer monthly averaged maps of the upper-tropospheric flow over the oceans. The transient part of these climatological features is composed of TUTT cells and their origin is the subject of this study. TUTT cells often occur to the east of tropical cyclones. A nonlinear shallow

Rosana Nieto Ferreira; Wayne H. Schubert

1999-01-01

156

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

157

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

158

Dynamics of vortex Rossby waves in tropical cyclones  

NASA Astrophysics Data System (ADS)

This thesis describes an analytical study of vortex Rossby waves in tropical cyclones. Observational analyses of hurricanes in the tropical atmosphere indicate the existence of spiral rainbands which propagate outwards from the eye and affect the structure and intensity of the hurricane. These disturbances may be described as vortex Rossby waves. The aim of this research is to study the propagation of vortex Rossby waves in tropical cyclones and wave-mean-flow interactions near the critical radius where the mean flow angular velocity matches the phase speed of the waves. Depending on the wave magnitude, the problem can be linear or nonlinear. Analytical techniques including Laplace transforms, multiple scaling and asymptotic expansions are used to obtain approximate solutions of the governing linear and nonlinear equations. In this study we carry out asymptotic analyses to examine the evolution of the interactions near the critical radius in some two-dimensional configurations on an f-plane and a beta-plane. The results are used to explain some features of the tropical cyclone's development, namely, the change of angular wind in the critical layer, the secondary eyewall formation and the eyewall dynamics.

Nikitina, Lidia

159

Coastal Hazard due to Tropical Cyclones in Mexico  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

160

Monitoring tropical cyclone evolution with NOAA satellite microwave observations  

NASA Technical Reports Server (NTRS)

NOAA satellite microwave soundings, which penetrate high clouds, delineate the development and dissipation of the upper tropospheric warm core associated with a tropical cyclone. The storm's 'core" may be detected from microwave imagery. Vertical cross sections reveal the intensification of the upper tropospheric warm core as the storm develops, and the downward propagation of the warm core as the storm dissipates. Excellent correlation is found between the horizontal Laplacian of an upper tropospheric temperature field and the intensity of the storm, as categorized by its surface central pressure and maximum sustained wind speed at the eye wall. The microwave monitoring of tropical cyclones is achieved in real time at the University of Wisconsin's Space Science and Engineering Center through high-speed teleconnections to direct readout receiving systems at Wallops Island, Virginia and Redwood City, California.

Velden, C.; Smith, W. L.

1983-01-01

161

Satellite Analysis of Tropical Cyclones Using the Advanced Microwave Sounding Unit (AMSU)  

Microsoft Academic Search

The first Advanced Microwave Sounding Unit (AMSU) was launched aboard the NOAA-15 satellite on 13 May 1998. The AMSU is well suited for the observation of tropical cyclones because its measurements are not significantly affected by the ice clouds that cover tropical storms. In this paper, the following are presented: 1) upper-tropospheric thermal anomalies in tropical cyclones retrieved from AMSU

Stanley Q. Kidder; Mitchell D. Goldberg; Raymond M. Zehr; Mark DeMaria; James F. W. Purdom; Christopher S. Velden; Norman C. Grody; Sheldon J. Kusselson

2000-01-01

162

Title of Dissertation: THEORETICAL AND NUMERICAL STUDIES OF TROPICAL CYCLONE DEVELOPMENT  

E-print Network

ABSTRACT Title of Dissertation: THEORETICAL AND NUMERICAL STUDIES OF TROPICAL CYCLONE DEVELOPMENT the vortex merger. #12;THEORETICAL AND NUMERICAL STUDIES OF TROPICAL CYCLONE DEVELOPMENT By Chanh Q. Kieu of Atmospheric and Oceanic Science Part I of this dissertation is devoted to a theoretical study of tropical

Maryland at College Park, University of

163

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

NASA Technical Reports Server (NTRS)

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

Wilson, Robert M.

2007-01-01

164

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

165

The Effect of Vertical Shear on Tropical Cyclone Intensity Change  

Microsoft Academic Search

The effect of vertical shear on tropical cyclone intensity change is usually explained in terms of `ventilation' where heat and moisture at upper levels are advected away from the low-level circulation, which inhibits development. A simple two-layer diagnostic balance model is used to provide an alternate explanation of the effect of shear. When the upper-layer wind in the vortex environment

Mark Demaria

1996-01-01

166

How may tropical cyclones change in a warmer climate?  

Microsoft Academic Search

Tropical cyclones (TC) under different climate conditions in the Northern Hemisphere have been investigated with the Max Planck Institute (MPI) coupled (ECHAM5\\/MPI-OM) and atmosphere (ECHAM5) climate models. The intensity and size of the TC depend crucially on resolution with higher wind speed and smaller scales at the higher resolutions. The typical size of the TC is reduced by a factor

Lennart Bengtsson; Kevin I. Hodges; Monika Esch; Noel Keenlyside; Luis Kornblueh; Jing-Jia Luo; Toshio Yamagata

2007-01-01

167

The Variation of Tropical Cyclone Rainfall within the North Atlantic and Pacific as Observed from Satellites  

NASA Technical Reports Server (NTRS)

Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations in the North Atlantic and in three equal geographical regions of the North Pacific (i.e., Western, Central, and Eastern North Pacific). These satellite-derived rainfall amounts are used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the 1987-1989, 1991-1998 North Atlantic and Pacific rainfall during June-November when tropical cyclones are most abundant. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from the Defence Meteorological Satellite Program (DMSP) Special Sensor Microwave/ Radiometer (SSM/I) observations within 444 km radius of the center of those North Atlantic and Pacific tropical cyclones that reached storm stage and greater. These rain rate observations are then multiplied by the number of hours in a given month. Mean monthly rainfall amounts are also constructed for all the other North Atlantic and Pacific raining systems during this eleven year period for the purpose of estimating the geographical distribution and intensity of rainfall contributed by non-tropical cyclone systems. Further, the combination of the non-tropical cyclone and tropical cyclone (i.e., total) rainfall is constructed to delineate the fractional amount that tropical cyclones contributed to the total North Pacific rainfall.

Rodgers, Edward; Pierce, Harold; Adler, Robert

1999-01-01

168

Nimbus-7 total ozone observations of western North Pacific tropical cyclones  

NASA Technical Reports Server (NTRS)

The Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) was used to map the distribution of total ozone around western North Pacific tropical cyclones from 1979 to 1982. The strong correlation between total ozone distribution and tropopause height found in the subtropical and midlatitudes made it possible for TOMS to monitor the propagation of upper-tropospheric waves and the mutual adjustment between these waves and tropical cyclones during their interaction. Changes in these total ozone patterns reflect the 3D upper-tropospheric transport processes that are involved in tropical cyclone intensity and intensity and motion changes. The total ozone distributions indicate that: (1) the mean upper-tropospheric circulations associated with western North Pacific and Atlantic tropical cyclones are similar; (2) more intense tropical cyclones have higher tropopauses around their centers; (3) more intense tropical cyclones have higher tropopauses on the anticyclonic-shear side of their outflow jets, which indicate that the more intense tropical cyclones have stronger outflow channels than less intense systems; (4) tropical cyclones that intensify (do not intensify) are within 10 deg (15 deg) latitude of weak (strong) upper-tropospheric troughs that are moderately rich (very rich) in total ozone; and (5) tropical cyclones turn to the left (right) when they move within approximately 15 deg latitude downstream of an ozone-poor (ozone-rich) upper-tropospheric ridge (trough).

Stout, John; Rodgers, Edward B.

1992-01-01

169

Heightened tropical cyclone activity in the North Atlantic: natural variability or  

E-print Network

Heightened tropical cyclone activity in the North Atlantic: natural variability or climate trend cyclone and hurricane frequency over the past century in the North Atlantic Ocean have occurred as three relatively stable regimes separated by sharp transitions. Each regime has seen 50% more cyclones

Webster, Peter J.

170

The Extratropical Transition of Tropical Cyclones: Forecast Challenges, Current Understanding, and Future Directions  

Microsoft Academic Search

A significant number of tropical cyclones move into the midlatitudes and transform into extratropical cyclones. This process is generally referred to as extratropical transition (ET). During ET a cyclone frequently produces intense rainfall and strong winds and has increased forward motion, so that such systems pose a serious threat to land and maritime activities. Changes in the structure of a

Sarah C. Jones; Patrick A. Harr; Jim Abraham; Lance F. Bosart; Peter J. Bowyer; Jenni L. Evans; Deborah E. Hanley; Barry N. Hanstrum; Robert E. Hart; Franois Lalaurette; Mark R. Sinclair; Roger K. Smith; Chris Thorncroft

2003-01-01

171

On African easterly waves that impacted two tropical cyclones in 2004 Melinda S. Peng,1  

E-print Network

On African easterly waves that impacted two tropical cyclones in 2004 Melinda S. Peng,1 Bing Fu,2 cyclones. Danielle and Earl (2004) formed approximately at the same time in the Atlantic. A three to eight of the African easterly waves related to the two cyclones. The time-filtered 850 mb vorticity shows that African

Li, Tim

172

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

E-print Network

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

Emanuel, Kerry Andrew

173

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

174

Hydrological Balance in Tropical Cyclones with Scatterometer and TRMM Data  

NASA Technical Reports Server (NTRS)

Precipitation over oceans can be estimated from the radar and the microwave radiometer of the Tropical Rain Measuring Mission (TRMM). It can also be estimated from the divergence of the vertically integrated water vapor transport, through the conservation principle, assuming evaporation is relatively small. In tropical cyclones, the divergence of vertically integrated water vapor is highly dependent on the vertical transport and, therefore, on the wind divergence. Spaceborne scatterometers provide surface wind velocity and, therefore, surface wind divergence at spatial resolutions that are much higher than products of numerical weather prediction (NWP). In this study, ocean surface winds derived from the observations of space-based scatterometers and surface precipitation measured by TRMM were objectively interpolated to the same time and location during the passage of a tropical cyclone. Surface precipitation distribution was derived from wind and humidity profiles provided by NWP. When the surface level winds of NWP were replaced by the scatterometer winds, the surface precipitation patterns computed with the conservation method were found to be significantly changed and the new patterns are much closer in agreement with the patterns observed by TRMM.

Liu, W. Timothy; Hua, Hu; Tang, Wenqing

2000-01-01

175

Tropical Cyclones and Global Climate Change: A Post-IPCC Assessment  

Microsoft Academic Search

The very limited instrumental record makes extensive analyses of the natural variability of global tropical cyclone activities difficult in most of the tropical cyclone basins. However, in the two regions where reasonably reliable records exist (the North Atlantic and the western North Pacific), substantial multidecadal variability (particularly for intense Atlantic hurricanes) is found, but there is no clear evidence of

A. Henderson-Sellers; H. Zhang; G. Berz; K. Emanuel; W. Gray; C. Landsea; G. Holland; J. Lighthill; S.-L. Shieh; P. Webster; K. McGuffie

1998-01-01

176

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

177

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.

178

Impact of tropical cyclones on the ocean heat budget in the Bay of Bengal during 1999  

E-print Network

estimates using previously published methods based on surface observations. The relatively weak heat pumping pumping (DOHP) by tropical cyclones (TCs), which mea- sures the amount of heat that is pumped down fromImpact of tropical cyclones on the ocean heat budget in the Bay of Bengal during 1999: 2. Processes

Han, Weiqing

179

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

E-print Network

frequency of events is consistent with increases in a genesis potential index based on monthly mean global of global warming on tropical cyclones. climate change | natural hazards Some 90 tropical cyclones develop as the planet warms (e.g., refs. 4, 5). Although global warming increases the thermodynamic po- tential

Rothman, Daniel

180

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

E-print Network

Response of tropical cyclone potential intensity over the north Indian Ocean to global warming the background PI is already high and the potentially longer TC season in response to global warming due of tropical cyclone potential intensity over the north Indian Ocean to global warming, Geophys. Res. Lett., 36

Wang, Yuqing

181

13.5 THE IMPORTANCE OF THE PRECIPITATION MASS SINK IN TROPICAL CYCLONES Richard M. Yablonsky*  

E-print Network

in which phase changes of water and/or precipitation are occurring. Therefore, eq. (1) should be rewritten height is proportional to the total mass of the overlying air. Therefore, water mass removal via downward. Precipitation mass sink in tropical cyclones. 3. TROPICAL CYCLONE MASS BUDGET: HURRICANE LILI (2002) MM5

Rhode Island, University of

182

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

E-print Network

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

Nolan, David S.

183

PUBLISHED ONLINE: 11 JULY 2010 | DOI: 10.1038/NPHYS1725 Scaling of tropical-cyclone dissipation  

E-print Network

LETTERS PUBLISHED ONLINE: 11 JULY 2010 | DOI: 10.1038/NPHYS1725 Scaling of tropical-cyclone and global warming on the occurrence of tropical cyclones is a controversial issue1­10 . Existing historical of basic understanding regarding the intrinsic nature of tropical- cyclone genesis and evolution14

Loss, Daniel

184

Impact of the Intraseasonal Variability of the Western North Pacific Large-Scale Circulation on Tropical Cyclone Tracks  

E-print Network

on Tropical Cyclone Tracks Tsing-Chang Chen1* , Shih-Yu Wang1 , Ming-Cheng Yen2 , and Adam J. Clark1 1-west seesaw oscillation. Previous studies have shown that the characteristics of tropical cyclone tracks was made in this study to disclose the impact of monsoon life cycle on tropical cyclone tracks. A majority

Chen, Tsing-Chang "Mike"

185

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 tropical cyclones (sustained winds >= 39 mph), nine hurricanes (sustained winds >= 74 mph), and six intense tropical cyclones, nine hurricanes, and six major hurricanes de- veloped during the season, and Hurricanes

Gray, William

186

Tropical Cyclone Intensity Change before U.S. Gulf Coast Landfall EDWARD N. RAPPAPORT AND JAMES L. FRANKLIN  

E-print Network

Tropical Cyclone Intensity Change before U.S. Gulf Coast Landfall EDWARD N. RAPPAPORT AND JAMES L (Manuscript received 21 October 2009, in final form 28 May 2010) ABSTRACT Tropical cyclone intensity change along the Gulf of Mexico. Analysis of 1979­2008 Gulf tropical cyclones during their final two days

Miami, University of

187

SUMMARY OF 2011 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHOR'S SEASONAL AND TWO-WEEK FORECASTS  

E-print Network

SUMMARY OF 2011 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHOR'S SEASONAL AND TWO-WEEK FORECASTS The 2011 hurricane season had above-average tropical cyclone activity but not to the levels that we predicted. It was notable for having many weak tropical cyclones but only slightly above

188

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

NASA Technical Reports Server (NTRS)

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

Rodgers, Edward B.; Stout, John

1989-01-01

189

HILDERBRAND, DOUGLAS CLARENCE. Risk assessment of North Carolina tropical cyclones (1925-2000). (Under the direction of Dr. Lian Xie)  

E-print Network

ABSTRACT HILDERBRAND, DOUGLAS CLARENCE. Risk assessment of North Carolina tropical cyclones (1925-2000). (Under the direction of Dr. Lian Xie) Previous tropical cyclone risk assessment studies have been realistic measure of impact. Using the new normalization method, 1954-55 tropical cyclone storm totals

Liu, Paul

190

Distinct effects of anthropogenic aerosols on tropical cyclones  

NASA Astrophysics Data System (ADS)

Long-term observations have revealed large amplitude fluctuations in the frequency and intensity of tropical cyclones (TCs; refs , , , ), but the anthropogenic impacts, including greenhouse gases and particulate matter pollution, remain to be elucidated. Here, we show distinct aerosol effects on the development of TCs: the coupled microphysical and radiative effects of anthropogenic aerosols result in delayed development, weakened intensity and early dissipation, but an enlarged rainband and increased precipitation under polluted conditions. Our results imply that anthropogenic aerosols probably exhibit an opposite effect to that of greenhouse gases, highlighting the necessity of incorporating a realistic microphysical-radiative interaction of aerosols for accurate forecasting and climatic prediction of TCs in atmospheric models.

Wang, Yuan; Lee, Keun-Hee; Lin, Yun; Levy, Misti; Zhang, Renyi

2014-05-01

191

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

192

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

193

Tropical cyclone Dera, the unusual 2000/01 tropical cyclone season in the South West Indian Ocean and associated rainfall anomalies over Southern Africa  

NASA Astrophysics Data System (ADS)

Austral summer 2000/01 in the southern African region was unusual in several respects. Tropical cyclone activity in the southwest Indian Ocean was substantially less than average despite large areas of this region showing anomalously warm sea surface temperatures (SST) for much of the season. Many areas of southern Africa experienced above average rainfall with local flooding in parts of Mozambique. In the tropical southeast Atlantic, a large warm SST anomaly evolved off the coast of Angola and northern Namibia in late summer suggesting a Benguela Nio event. During the late summer (February April 2001), three particularly widespread and intense wet spells occurred over tropical southern Africa, one of which coincided with tropical cyclone Dera. This study considers the generation and evolution of the middle wet spell of late summer 2001 and its relationship with tropical cyclone Dera. This storm was generated in the northwestern part of the Mozambique Channel and then tracked more or less due south through the Channel and into the subtropical southwest Indian Ocean. Rainfall associated with Dera contributed to the ongoing floods over central Mozambique that arose from rains earlier in the season. Dera occurred in early March following a relatively long period of no tropical cyclone activity in the southwest Indian Ocean. A build up of favorable conditions during the preceding weeks contributed towards the storm whereas an anticyclonic anomaly east of Madagascar led to the northerly steering current and the southward track of tropical cyclone Dera out of the Mozambique Channel.

Struchtrup, Henning; Thatcher, Toby

2007-08-01

194

The impacts of future climate changes on tropical cyclones are still uncertain. Here, we investigate their response to past climate changes with a model  

E-print Network

The impacts of future climate changes on tropical cyclones are still uncertain. Here, we influenced the tropical cyclone distribution. Tropical Cyclones at the Last Glacial Maximum Chris Brierley1. Sci. 32, 111-149 Emanuel & Nolan, 2004. Tropical cyclone activity and global climate. Preprints, 26th

Jones, Peter JS

195

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

NASA Technical Reports Server (NTRS)

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

Rodgers, Edward B.; Stout, John

1990-01-01

196

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

197

Numerical Simulation of a Quasi-Tropical Cyclone over the Black Sea  

E-print Network

The paper describes results of numerical experiments on the simulation of a mesoscale quasi-tropical cyclone, a rare event for the Black Sea, with the MM5 regional atmospheric circulation model. General characteristics of the cyclone and its evolution and physical formation mechanisms are discussed. The balances of the momentum components have been estimated, and sensitivity experiments have been performed. It is shown that, according to its main physical properties and energy supply mechanisms, the cyclone can be related to quasi-tropical cyclones.

Efimov, V V; Yarovaya, D A

2009-01-01

198

Testing coral-based tropical cyclone reconstructions: An example from Puerto Rico  

USGS Publications Warehouse

Complimenting modern records of tropical cyclone activity with longer historical and paleoclimatological records would increase our understanding of natural tropical cyclone variability on decadal to centennial time scales. Tropical cyclones produce large amounts of precipitation with significantly lower ?18O values than normal precipitation, and hence may be geochemically identifiable as negative ?18O anomalies in marine carbonate ?18O records. This study investigates the usefulness of coral skeletal ?18O as a means of reconstructing past tropical cyclone events. Isotopic modeling of rainfall mixing with seawater shows that detecting an isotopic signal from a tropical cyclone in a coral requires a salinity of ~ 33 psu at the time of coral growth, but this threshold is dependent on the isotopic composition of both fresh and saline end-members. A comparison between coral ?18O and historical records of tropical cyclone activity, river discharge, and precipitation from multiple sites in Puerto Rico shows that tropical cyclones are not distinguishable in the coral record from normal rainfall using this approach at these sites.

Kilbourne, K. Halimeda; Moyer, Ryan P.; Quinn, Terrence M.; Grottoli, Andrea G.

2011-01-01

199

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

200

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

201

Statistical Aspects of Tropical Cyclone Activity in the North Atlantic Basin, 1945-2010  

NASA Technical Reports Server (NTRS)

Examined are statistical aspects of the 715 tropical cyclones that formed in the North Atlantic basin during the interval 1945-2010. These 715 tropical cyclones include 306 storms that attained only tropical storm strength, 409 hurricanes, 179 major or intense hurricanes, and 108 storms that struck the US coastline as hurricanes. Comparisons made using 10-year moving average (10-yma) values between tropical cyclone parametric values and surface air and ENSO-related parametric values indicate strong correlations to exist, in particular, against the Armagh Observatory (Northern Ireland) surface air temperature, the Atlantic Multi-decadal Oscillation (AMO) index, the Atlantic Meridional Mode (AMM) index, and the North Atlantic Oscillation (NAO) index, in addition to the Oceanic Ni o index (ONI) and Quasi-Biennial Oscillation (QBO) indices. Also examined are the decadal variations of the tropical cyclone parametric values and a look ahead towards the 2012 hurricane season and beyond.

Wilson, Robert M.

2012-01-01

202

Spatially adaptive ocean surface wind retrievals using satellite microwave scatterometer measurements over tropical cyclones  

NASA Astrophysics Data System (ADS)

An algorithm is presented which extends the capabilities of the NASA Scatterometer (NSCAT) Wind Retrieval Algorithm to include retrievals using 25 km wind vector cells (SARA-25) and individual normalized radar cross section measurement cells (SARA-max). This Spatially Adaptive Retrieval Algorithm (SARA) can retrieve very high resolution and precise tropical cyclone wind fields when using a model wind field with ideal (no noise, perfect model function) measurements. It is shown that the actual SARA-25 retrievals are very close to the 50 km NSCAT retrievals for a wide range of wind speeds and directions. The benefit from SARA is in cases where higher sampling is needed to fully describe the wind field. Regions such as the eyewall of a tropical cyclone where, measurements of peak winds are a high priority, are well suited for SARA analysis. Using only one measurement for a retrieval in an eyewall. eliminates the effects of averaging used in SARA-25 and 50 km sampling. The SARA also provides a means to test if adjacent measurements are similar to each other. Dissimilar measurements are most likely due to the effects of rain. Hence SARA provides a means to evaluate which cells are affected by rain.

Rice, Lawrence Philipp

203

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

204

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

205

Eastern Atlantic tropical cyclone frequency from 18511898 is comparable to satellite era frequency  

NASA Astrophysics Data System (ADS)

Trend in North Atlantic tropical cyclone frequency is subject to uncertainties related mainly to observational deficiencies. These uncertainties make assessments of anthropogenic effects on present and future trends problematic. Here we document that, contrary to received opinion, ship numbers actually peaked in the mid-nineteenth century and reached a minimum in the early twentieth century. The greater opportunities for ship encounters with tropical cyclones is demonstrated in re-analysis of Eastern Atlantic tropical cyclones from 18511898. Our results suggest that nineteenth century frequency is comparable to that for the same area during the entire satellite era from 19652012.

Chenoweth, Michael; Divine, Dmitry

2014-11-01

206

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

207

Tropical Cyclones in the Southwest Pacific: Spatial Patterns and Relationships to Southern Oscillation and Sea Surface Temperature  

Microsoft Academic Search

An analysis of a 20-yr dataset of tropical cyclones in the southwest Pacific has been made to determine the spatial patterns of cyclone occurrence and how these depend on the Southern Oscillation (SO) and sea surface temperature. A local measure of cyclone incidence is defined as the number of cyclones that enter into a 2 lat-long square during some period

R. E. Basher; X. Zheng

1995-01-01

208

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

209

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

NASA Technical Reports Server (NTRS)

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

Wilson, Robert M.

2001-01-01

210

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

NASA Technical Reports Server (NTRS)

Ten-year moving averages of the seasonal rates for "named storms," tropical storms, hurricanes, and major (or intense) hurricanes in the Atlantic basin reveal that the present epoch is one of enhanced activity (i.e., having seasonal rates typically equal to or above respective long-term median rates). For example, the 10-year moving average of the seasonal rates for named storms is now higher than for any previous year over the past 50 years, measuring 10.65 in 1994, or 2.65 units higher than its median rate of 8. For tropical storms, its 10-year moving average has more than doubled over the past 50 years, from 2.15 in 1955 to 4.60 in 1992, with 16 of the past 20 years having a seasonal rate of 3 or more (the median rate). For hurricanes and major hurricanes, their 10-year moving averages turned upward, rising above long-term median rates (5.5 and 2, respectively) in 1992, following a 25-year lull in activity. Taken together, the outlook for this year and immediately succeeding years is for all categories of Atlantic basin tropical cyclones to have seasonal rates at levels equal to or above their long-term median rates, especially during non-El Nino-related seasons. Only during El Nino-related seasons does it appear that seasonal rates might be slightly diminished.

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

2000-01-01

211

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 25S, 160E to 120W. 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 25S to 40S, 160E to 120W and with the data from TCWCs in Brisbane and Darwin for the area south of the equator to 37S, 135E to 160E. 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 Runion 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

212

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

213

On the Use of Two-Dimensional Incompressible Flow to Study Secondary Eyewall Formation in Tropical Cyclones  

E-print Network

Cyclones YUMIN MOON, DAVID S. NOLAN, AND MOHAMED ISKANDARANI Rosenstiel School of Marine and Atmospheric eyewall formation in tropical cyclones by using two-dimensional incompressible flow. Those studies as the tropical cyclone core or as purely asymmetric vorticity perturbations that are an order of magnitude weaker

Miami, University of

214

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

215

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

216

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

217

Tropical Cyclone Forecasting Applications of the GOES WMSI  

E-print Network

The Geostationary Operational Environmental Satellite (GOES) sounder-derived Wet Microburst Severity Index (WMSI) was originally developed and implemented to assess the potential magnitude of convective downbursts over the central and eastern continental United States. The WMSI algorithm incorporates convective available potential energy (CAPE), to parameterize static instability, as well as the vertical theta-e (equivalent potential temperature) difference (TeD) between the surface and mid-troposphere to infer the presence of a mid-level dry air layer. It has been noted with two recent landfalling hurricanes over the Florida Gulf of Mexico coast that the GOES WMSI product accurately predicted downburst magnitude associated with convective bands and the eye wall. As a convective system, it is expected that tropical cyclones can be profilic downburst producing storms. In fact, several severe downbursts were observed in association with the pre-hurricane squall line and remnant eye wall of Hurricane Charley (Au...

Pryor, K L

2006-01-01

218

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

219

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

220

Tropical CycloneInduced Upper-Ocean Mixing and Climate: Application to Equable Climates  

Microsoft Academic Search

Tropical cyclones instigate an isolated blast of vigorous mixing in the upper tropical oceans, stirring warm surface water with cooler water in the thermocline. Previous work suggests that the frequency, intensity, and lifetime of these storms may be functions of the climate state, implying that transient tropical mixing could have been stronger during warmer equable climates with higher concentrations of

Robert L. Korty; Kerry A. Emanuel; Jeffery R. Scott

2008-01-01

221

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

222

Tropical Cyclone Activity Downscaled from NOAA-CIRES Reanalysis, 1908-1958  

E-print Network

A recently developed technique for deducing tropical cyclone activity from global reanalyses and climate models is applied to a reanalysis of the global atmosphere during the period 1908-1958. This reanalysis assimilates ...

Emanuel, Kerry Andrew

223

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

224

Rainfall Totals from the Tropical Cyclones Passing Over Philippines - Duration: 0:48.  

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...

225

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

E-print Network

Global Ensemble Predictions of 2009's Tropical Cyclones Initialized with an Ensemble Kalman Filter with the first 20 members of a 60-member ensemble Kalman filter (EnKF) using the T382L64 GFS. The GFS

Hamill, Tom

226

Improving Ocean Model Initialization for Coupled Tropical Cyclone Forecast Models Using GODAE Nowcasts  

E-print Network

of Mexico prior to Hurricanes Isidore and Lili (2002), Ivan (2004), and Katrina (2005). Evaluations by the con- densation of water evaporated from the sea surface. Tropical cyclone intensification is often

Shay, Lynn K. "Nick"

227

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

228

The poleward migration of the location of tropical cyclone maximum intensity  

E-print Network

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 ...

Kossin, James P.

229

Tropical Cyclone Mahasen Rain Moving Into Bay Of Bengal - Duration: 0:05.  

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...

230

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

231

TRMM Sees Rainfall Totals from Tropical Cyclone Guito - Duration: 0:06.  

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...

232

Tropical Cyclone Jack in Satellite 3-D - Duration: 0:13.  

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). ...

233

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

234

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

235

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

NASA Astrophysics Data System (ADS)

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

Kieu, Chanh; Tallapragada, Vijay; Hogsett, Wallace

2014-05-01

236

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

237

Tropical cyclone/upper-atmospheric interaction as inferred from satellite total ozone observations  

SciTech Connect

The Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) was used to map the distribution of total ozone within and surrounding western North Atlantic and North Pacific tropical cyclones that occurred from 1979-1982. It was found from numerical model simulations and diagnostics and satellite observations that the distribution of total ozone within the subtropical upper-tropospheric waves during the tropical cyclone season corresponded well with the variation of thermodynamic parameters (i.e., temperature, thickness, geopotential heights) near the tropopause and the regions of strong stratospheric and tropospheric exchange processes. These results are similar to previous middle latitudinal observations. It was also found that the three-dimensional transport processes associated with both the western North Atlantic and Pacific tropical cyclone's outflow jet induced secondary circulation and the strong vertical motions associated with active deep convective and eye regions helped to modify the total ozone distribution that is usually observed within these subtropical upper-tropospheric waves. The tropical cyclone induced modifications of the total ozone in the upper-tropospheric waves became greater as the tropical cyclone became more intense and the three-dimensional transpost processes associated with the outflow jet, convection and eye strengthened. The strong relationship between total ozone distribution and the variation of the tropopause topography, made it possible to use TOMS to monitor the propagation of the subtropical upper-tropospheric waves and the mutual adjustment between tropical cyclones and their upper-tropospheric and lower-stratospheric environment when these tropical cyclones and the upper-tropospheric waves interacted. These total ozone patterns during tropical cyclone and upper-tropospheric wave interaction reflected the three-dimensional upper-tropospheric transport processes that were conducive for storm intensification, weakening, or recurvature.

Rodgers, E.B.

1992-01-01

238

A 15Year Climatology of North Atlantic Tropical Cyclones. Part I: Size Parameters  

Microsoft Academic Search

The extended best-track (EBT) dataset combines the information contained in the tropical cyclone best-track dataset with measurements of tropical cyclone ``size parameters.'' These parameters include the radii of the eye (REYE), maximum winds (RMW), gale-force winds (or size; 17.5 m s-1; R17), damaging-force winds (25.7 m s-1; R26), hurricane-force winds (32.9 m s-1; R33), and the outermost closed isobar (ROCI).

Sytske K. Kimball; Madhuri S. Mulekar

2004-01-01

239

Scaling laws for the tropical cyclone derived from the stationary atmospheric vortex equation  

E-print Network

We present results of a numerical study of the differential equation governing the stationary states of the two-dimensional planetary atmosphere and magnetized plasma (within the Charney Hasegawa Mima model). The results show an interesting similarity with the morphology of a tropical cyclone. Quantitative comparisons are also favorable and several scaling laws can be formulated connecting the charactersistic physical parameters of the tropical cyclone.

Spineanu, F; Spineanu, Florin; Vlad, Madalina

2006-01-01

240

Large-Scale Characteristics of Rapidly Intensifying Tropical Cyclones in the North Atlantic Basin  

Microsoft Academic Search

The National Hurricane Center (NHC) and Statistical Hurricane Intensity Prediction Scheme (SHIPS) databases are employed to examine the large-scale characteristics of rapidly intensifying Atlantic basin tropical cyclones. In this study, rapid intensification (RI) is defined as approximately the 95th percentile of over-water 24-h intensity changes of Atlantic basin tropical cyclones that developed from 1989 to 2000. This equates to a

John Kaplan; Mark Demaria

2003-01-01

241

The Effects of Vertical Wind Shear on the Distribution of Convection in Tropical Cyclones  

Microsoft Academic Search

The influence of vertical wind shear on the azimuthal distribution of cloud-to-ground lightning in tropical cyclones was examined using flash locations from the National Lightning Detection Network. The study covers 35 Atlantic basin tropical cyclones from 1985-99 while they were over land and within 400 km of the coast over water. A strong correlation was found between the azimuthal distribution

Kristen L. Corbosiero; John Molinari

2002-01-01

242

Tropical Cyclones Feed More Heavy Rain in a Warmer Climate  

NASA Technical Reports Server (NTRS)

The possible linkage of tropical cyclones (TC) to global warming is a hotly debated scientific topic, with immense societal impacts. Most of the debate has been focused on the issue of uncertainty in the use of non-research quality data for long-term trend analyses, especially with regard to TC intensity provided by TC forecasting centers. On the other hand, it is well known that TCs are associated with heavy rain during the processes of genesis and intensification, and that there are growing evidences that rainfall characteristics (not total rainfall) are most likely to be affected by global warming. Yet, satellite rainfall data have not been exploited in any recent studies of linkage between tropical cyclones (TC) and global warming. This is mostly due to the large uncertainties associated with detection of long-term trend in satellite rainfall estimates over the ocean. This problem, as we demonstrate in this paper, can be alleviated by examining rainfall distribution, rather than rainfall total. This paper is the first to use research-quality, satellite-derived rainfall from TRMM and GPCP over the tropical oceans to estimate shift in rainfall distribution during the TC season, and its relationships with TCs, and sea surface temperature (SST) in the two major ocean basins, the northern Atlantic and the northern Pacific for 1979-2005. From the rainfall distribution, we derive the TC contributions to rainfall in various extreme rainfall categories as a function to time. Our results show a definitive trend indicating that TCs are contributing increasingly to heavier rain events, i.e., intense TC's are more frequent in the last 27 years. The TC contribution to top 5% heavy rain has nearly doubled in the last two decades in the North Atlantic, and has increased by about 10% in the North Pacific. The different rate of increase in TC contribution to heavy rain may be related to the different rates of different rate of expansion of the warm pool (SST >2S0 C) area in the two oceans.

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

2007-01-01

243

Interdecadal variation of Korea affecting tropical cyclone intensity  

NASA Astrophysics Data System (ADS)

This study analyzed a time series of average central pressure of tropical cyclone (TC) that affected Korea in summer season from 1965 to 2012. To determine whether climate regime shift exists in this time series, statistical change-point analysis was applied to this time series. The result showed that significant climate regime shift existed in 1989, that is, TC intensity from 1965 to 1988 (6588) was weaker than that from 1989 to 2012 (8912). Therefore, an average difference between former and latter periods was analyzed to study large-scale environments, which caused such difference. While TC genesis frequency showed a tendency that TCs in the 6588 period were originated from the northwest quadrant in the tropical and subtropical western North Pacific, TCs in the 8912 period were originated from the southeast quadrant. Thus, it was judged that TCs in the 6588 were generated at a higher latitude followed by moving to Korea, so their strength was weaker than those of TCs of 8912 due to lack of time to acquire sufficient energy from the sea. For TC passage frequency, TCs in the 6588 period showed a tendency to move a short distance from the sea far away from the southeast in Japan to the sea far away from the northeast in Japan or toward the East China Sea. On the other hand, TCs in the 8912 period moved a longer distance from the sea far away from the Philippines via Japan to the eastern sea of Kamchatka Peninsular or toward the east region in China. As such, an average difference of intensity between the former period and the latter period over the 500-hPa streamline was analyzed to determine why the intensity of TCs in the 6588 period was weaker than that of TCs in the 8912 period. As a result, anomalous cold northerlies from anomalous cyclones based on the northern territory of Japan were predominant, while these anomalous flows were originated from the tropical and subtropical western Pacific followed by moving to Korea, thereby affecting the weakening of the TC intensity. Negative anomaly in 500 and 850 hPa air temperature, 600 hPa relative humidity, precipitable water, and sea surface temperature accounted for most of the analysis between the two periods, thereby forming disadvantageous atmospheric environments for strengthening the TC intensity.

Choi, Ki-Seon; Cha, Yu-Mi; Kang, Sung-Dae; Kim, Hae-Dong

2014-06-01

244

Tropical cyclone-upper atmospheric interaction as inferred from satellite total ozone observations  

NASA Technical Reports Server (NTRS)

The Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) was used to map the distribution of total ozone in and around western Atlantic tropical cyclones from 1979 to 1982. It was found that the TOMS-observed total ozone distribution within the subtropics during the tropical cyclone season correlated well with the tropopause topography, similar to earlier middle-latitudinal observations. This relationship made it possible to use TOMS to monitor the propagation of upper-tropospheric subtropical transient waves and the mutual adjustment between the tropical cyclone and the upper-tropospheric waves during their interaction. These total ozone patterns reflected the three-dimensional upper-tropospheric transport processes that were conducive for storm intensification and weakening. It was also found from satellite observations and numerical model simulations that modification of the environmental distribution of total ozone by the tropical cyclones was primarily caused by the secondary circulation associated with the tropical cyclone's outflow jet and the intrusion of stratospheric air in the eyes of tropical cyclones.

Rodgers, Edward B.; Stout, John; Steranka, Joseph; Chang, Simon

1990-01-01

245

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

NASA Astrophysics Data System (ADS)

We describe the first use of a fully integrated biogeochemical model to explore the response of a marine shelf system to a tropical cyclone. Ocean currents, nutrients, sediments and plankton dynamics were simulated under conditions representative of Tropical Cyclone Bobby, which traversed the Australian North West Shelf in February 1995. Results show strong upwelling of nutrients and a phytoplankton bloom. While chlorophyll changes were similar to those estimated from satellite data in other coastal systems exposed to cyclonic conditions, the overall phytoplankton response was limited by cyclone induced sediment resuspension and the net contribution to annual primary production on the shelf was relatively small. In contrast, sediment loads exported off the shelf during Bobby were found to be more than 50 times modeled annual loads in years with little cyclone exposure and equivalent to at least 20 years of annual river-loads to the North West Shelf.

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

2009-11-01

246

Diabatic and frictional forcing effects on the structure and intensity of tropical cyclones  

NASA Astrophysics Data System (ADS)

Tropical cyclone intensity forecasting skill has slowed in improvement for both dynamical and statistical-dynamical forecasting methods in comparison to gains seen in track forecasting skill. Also, forecast skill related to rapid intensification, e.g. a 30 kt or greater increase in intensity within a 24-hour period, still remains poor. In order to make advances and gain a greater understanding, the processes that affect intensity change, especially rapid intensification, need further study. This work evaluates the roles of diabatic and frictional forcing on the structure and intensity of tropical cyclones. To assess the diabatic forcing effects on intensity change in tropical cyclones, this study develops applications of Eliassen's balanced vortex model to obtain one-dimensional solutions to the geopotential tendency and two-dimensional solutions to the transverse circulation. The one-dimensional balanced solutions are found with dynamical model outputs as well as aircraft reconnaissance combined with diabatic heating derived from microwave rainfall rate retrievals. This work uses solutions from both datasets to make short-range intensity predictions. The results show that for the one-dimensional solutions, the tangential tendency does not match the dynamical model or aircraft wind tendencies. To relax the assumptions of the one-dimensional solutions to the geopotential tendency, solutions for idealized vortices are examined by finding two-dimensional solutions to the transverse circulation. The two-dimensional solutions allow for evaluation of the axisymmetric structure of the vortex on the (r, z)-plane without setting the baroclinicity to zero and the static stability to a constant value. While the sensitivity of tangential wind tendency to diabatic forcing and the region of high inertial stability is more realistic in the two-dimensional results, the solutions still neglect the influence of friction from the boundary layer. To understand further the role of frictional forcing in the boundary layer, two analytical slab models developed in this study provide insight into recent work that demonstrates how dry dynamics plays a role in determining eyewall location and size, how potential vorticity rings develop, and how an outer concentric eyewall forms through boundary layer "shock-like" structures. The analytical models show that when horizontal diffusion is neglected, the u(? u/? r) term in the radial equation of motion and the u[f + (? v/? r) + (v/r)] term in the tangential equation of motion develop discontinuities in the radial and tangential wind, with associated singularities in the boundary layer pumping and the boundary layer vorticity. The analytical models provide insight into the boundary layer processes that are responsible for determining the location of the eyewall and the associated diabatic heating that ultimately impacts the intensity of the tropical cyclone. This work shows that future research linking the roles of frictional forcing in the boundary layer to the diabatic forcing aloft while using a balanced model will be important for gaining insight into forcing effects on tropical cyclone intensity.

Slocum, Christopher J.

247

Wind and Pressure Fields Near Tropical Cyclone Oliver Derived from Scatterometer Observations  

NASA Technical Reports Server (NTRS)

The results of this study demonstrate that the surface wind velocity and pressure fields derived from spaceborne scatterometers are useful in monitoring the location and intensity of tropical cyclones. Satellite-borne microwave scatterometers can penetrate the cloudy core regions of tropical cyclones to resolve the circulation in detail over data sparse regions. The location of the cyclone observed by the ERS-1 (First European Remote Sensing Satellite) scatterometer is very close to that revealed in Geostationary Meteorological Satellite images. The surface winds provided by the ERS-1 scatterometer are used here with a modified two-layer planetary boundary layer model which includes effects of curvature, stability, and secondary flow to derive surface pressures near tropical cyclone Oliver. The curvature effect is found to be more significant than stability and secondary flow, which are crucial in deriving accurate surface pressure fields in midlatitudes.

Hsu, Carol S.; Liu, W. Timothy

1996-01-01

248

Wind and pressure Fields Near Tropical Cyclone Oliver Derived From Scatterometer Observations  

NASA Technical Reports Server (NTRS)

The results of this study demonstrate that the surface wind velocity and pressure fields derived from spaceborne scatterometers are useful in monitoring the location and intensity of tropical cyclones. Satellite-borne microwave scatterometers can penetrate the cloudy core regions of tropical cyclones to resolve the circulation in detail over data sparse regions. The location of the cyclone observed by the ERS-1 scatterometer is very close to that revealed in Geostationary Meteorological Satellite images. The surface winds provided by the ERS-1 scatterometer are used here with a modified two-layer planetary boundary layer model which includes effects of curvature, stability, and secondary flow to derive surface pressures near tropical cyclone Oliver. The curvature effect is found to be more significant than stability and secondary flow, which are crucial in deriving accurate surface pressure fields in midlatitudes.

Hsu, Carol S.; Liu, W. Timothy

1996-01-01

249

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

250

The roles of ENSO on the occurrence of abruptly recurving tropical cyclones over the Western North Pacific Ocean Basin  

E-print Network

Abstract. The abruptly recurving tropical cyclones over the Western North Pacific Ocean Basin during El Nio and La Nia events are studied. Temporal and spatial variations of these anomalous tracks under different phases of ENSO are shown. The anomalies of the pressure field in relation to ENSO circulation for the occurrence of the abruptly recurving cyclone tracks are investigated using fuzzy method. These are supplemented by wind field analyses. It is found that the occurrence of recurving-left (RL) and recurvingright (RR) tropical cyclones under the modification of the steering currents, including the re-adjustment of the westerly trough, the expansion or contraction of the sub-tropical high pressure, the intensifying easterly flow and the strengthening of the cross-equatorial flow, can be in El Nio or La Nia events. Evidently, there is a higher chance of occurrence of anomalous tropical cyclone trajectories in El Nio rather than La Nia events, but there is not any pronounced spatial pattern of anomalous tropical cyclone tracks. By analyzing the pressure-field, it is seen RL (RR) tropical cyclones tend to occur when the subtropical high pressure is weak (strong) in El Nio and La Nia events. More importantly, how the internal force of tropical cyclones changed by the steering current, which relies upon the relative location of tropical cyclones to the re-adjustment of the weather systems, shows when and where RL and RR tropical cyclones occur in El Nio and La Nia events.

N. K. W. Cheung

251

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

252

New Frontiers: Tropical Cyclone Modeling with NCAR's Variable-Resolution General Circulation Model CAM-SE  

NASA Astrophysics Data System (ADS)

Modeling of tropical cyclones in General Circulation Models (GCMs) has traditionally proved challenging. Tropical cyclones are significantly under-resolved, if not completely unresolved, at traditional GCM grid resolutions of 50-300 km. However, recent gains in computational resources and advances in GCM model design now allow for GCM simulations with grid spacings as small as 12-30 km. At these resolutions, models are able to more effectively capture key features of tropical cyclones. This talk surveys a novel variable-resolution mesh approach that allows for high spatial resolutions in areas of interest. The statically-nested, variable-mesh option has recently been introduced into the cubed-sphere Spectral Element (SE) dynamical core of the Community Atmosphere Model (CAM) which is under development at various U.S. Department of Energy laboratories and the National Center for Atmospheric Research (NCAR). The talk gives an overview of the variable-resolution mesh approach, and evaluates its scientific properties. In particular, we will discuss the characteristics of tropical cyclone simulations in a variety of modeling frameworks. They include the representation of tropical cyclones in aqua-planet experiments, and showcase short-term and multi-decadal tropical cyclone simulations in CAM-SE when driven with prescribed sea surface temperatures. Special attention is paid to the characteristics of tropical cyclones in the grid transition regions, and the comparison of variable- and uniform-resolution experiments. It is shown that the variable-resolution CAM-SE model has the potential to become a future tool for regional climate assessments. In addition, we assess the performance of the CAM4 and CAM5 physical parameterization packages in variable-resolution aqua-planet simulations. In particular, we discuss the question whether current physics packages are scale-aware and whether or not the addition of increased resolution patches adds bias to key climate metrics such as rainfall and cloud fraction at the regional level.

Jablonowski, Christiane; Zarzycki, Colin

2014-05-01

253

Development of an Objective Scheme to Estimate Tropical Cyclone Intensity from Digital Geostationary Satellite Infrared Imagery  

Microsoft Academic Search

The standard method for estimating the intensity of tropical cyclones is based on satellite observations (Dvorak technique) and is utilized operationally by tropical analysis centers around the world. The technique relies on image pattern recognition along with analyst interpretation of empirically based rules regarding the vigor and organization of convection surrounding the storm center. While this method performs well enough

Christopher S. Velden; Timothy L. Olander; Raymond M. Zehr

1998-01-01

254

Long-term trends and interannual variability in tropical cyclone activity over the western North Pacific  

Microsoft Academic Search

While Landsea et al. (1996) show that the number of intense Atlantic hurricanes is on the decrease, the trend of tropical cyclone activity over the western North Pacific is found to be just the opposite. For the period 1959 to 1994, the number of tropical storms and typhoons went through a period of decrease and then an increase, showing an

Johnny C. L. Chan; Jiu-en Shi

1996-01-01

255

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

PubMed

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. PMID:24828193

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

2014-05-15

256

Pollution and dust aerosols modulating tropical cyclones intensities  

NASA Astrophysics Data System (ADS)

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

Rosenfeld, Daniel; Clavner, Michal; Nirel, Ronit

2011-10-01

257

Influence of upper ocean stratification interannual variability on tropical cyclones  

NASA Astrophysics Data System (ADS)

modes, such as the El Nio Southern Oscillation (ENSO), influence Tropical Cyclones (TCs) interannual activity through their effect on large-scale atmospheric environment. These climate modes also induce interannual variations of subsurface oceanic stratification, which may also influence TCs. Changes in oceanic stratification indeed modulate the amplitude of TCs-induced cooling, and hence the negative feedback of air-sea interactions on the TC intensity. Here we use a dynamical downscaling approach that couples an axisymmetric TC model to a simple ocean model to quantify this interannual oceanic control on TC activity. We perform twin experiments with contrasted oceanic stratifications representative of interannual variability in each TC-prone region. While subsurface oceanic variations do not significantly affect the number of moderate (Category 3 or less) TCs, they do induce a 30% change of Category 5 TC-days globally, and a 70% change for TCs exceeding 85 m s-1. TCs in the western Pacific and the southwestern Indian Ocean are most sensitive to oceanic interannual variability (with a 10 m s-1 modulation of the intensity of strongest storms at low latitude), owing to large upper ocean variations in response to ENSO. These results imply that a representation of ocean stratification variability should benefit operational forecasts of intense TCs and the understanding of their climatic variability.

Vincent, Emmanuel M.; Emanuel, Kerry A.; Lengaigne, Matthieu; Vialard, Jrme; Madec, Gurvan

2014-09-01

258

Measuring NWP Skill of Tropical Cyclones in Shanghai Meteorological Service  

NASA Astrophysics Data System (ADS)

A WRF based typhoon NWP system for operations, namely, the SMS-THRAPS (Shanghai Meteorological Service-Tropical cyclone High Resolution Analysis and Prediction System), has been developed in Shanghai Typhoon Institute (STI). It mainly consists of the Gridpoint Statistical Interpolation (GSI) data assimilation, a complex cloud analysis (CCS) package and the WRF3.5. A significant number of local observations such as SYNOP, SHIP, BUOY, METAR, AMDAR, CINRAD and AWS can be assimilated into the system. The model is configured with a mesh of 9 km horizontal resolution covering an area about 6000km5000km and a moving nest of 77 at 3 km grid distance. Numerical experiments for Super typhoon "MEGI" (2012) during landfall stage indicated that assimilation of local observations is very important for improving the accuracy of typhoon track, intensity forecasts, particularly, local rainfall distribution. The SMS-THRAPS performance in 2013 was evaluated and compared with ECWMF and JAPAN global numerical forecasts. The results show that SMS-THRAPS's track forecast is similar to ECWMF and better than JAPAN. SMS-THRAPS is the best in sea level pressure forecast at leading time < 42 hours, and worse than ECWMF, better than JAPAN at leading time > 42 hours. Key words: High resolution, Typhoon, Assimilation

Wang, Xiaofeng; Xu, Xiaolin; Chen, Baode

2014-05-01

259

Mean structure of tropical cyclones making landfall in mainland China  

NASA Astrophysics Data System (ADS)

The mean kinematic and thermodynamic structures of tropical cyclones (TCs) making landfall in mainland China are examined by using sounding data from 1998 to 2009. It is found that TC landfall is usually accompanied with a decrease in low-level wind speed, an expansion of the radius of strong wind, weakening of the upper-level warm core, and drying of the mid-tropospheric air. On average, the warm core of the TCs dissipates 24 h after landfall. The height of the maximum low-level wind and the base of the stable layer both increase with the increased distance to the TC center; however, the former is always higher than the latter. In particular, an asymmetric structure of the TC after landfall is found. The kinematic and thermodynamic structures across various areas of TC circulation differ, especially over the left-front and right-rear quadrants (relative to the direction of TC motion). In the left-front quadrant, strong winds locate at a smaller radius, the upper-level temperature is warmer with the warm core extending into a deep layer, while the wet air occupies a shallow layer. In the right-rear quadrant, strong wind and wet air dwell in an area that is broader and deeper, and the warmest air is situated farther away from the TC center.

Bai, Lina; Yu, Hui; Xu, Yinglong; Wang, Yuan

2014-06-01

260

Improving NASA's Multiscale Modeling Framework for Tropical Cyclone Climate Study  

NASA Technical Reports Server (NTRS)

One of the current challenges in tropical cyclone (TC) research is how to improve our understanding of TC interannual variability and the impact of climate change on TCs. Recent advances in global modeling, visualization, and supercomputing technologies at NASA show potential for such studies. In this article, the authors discuss recent scalability improvement to the multiscale modeling framework (MMF) that makes it feasible to perform long-term TC-resolving simulations. The MMF consists of the finite-volume general circulation model (fvGCM), supplemented by a copy of the Goddard cumulus ensemble model (GCE) at each of the fvGCM grid points, giving 13,104 GCE copies. The original fvGCM implementation has a 1D data decomposition; the revised MMF implementation retains the 1D decomposition for most of the code, but uses a 2D decomposition for the massive copies of GCEs. Because the vast majority of computation time in the MMF is spent computing the GCEs, this approach can achieve excellent speedup without incurring the cost of modifying the entire code. Intelligent process mapping allows differing numbers of processes to be assigned to each domain for load balancing. The revised parallel implementation shows highly promising scalability, obtaining a nearly 80-fold speedup by increasing the number of cores from 30 to 3,335.

Shen, Bo-Wen; Nelson, Bron; Cheung, Samson; Tao, Wei-Kuo

2013-01-01

261

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 characterized 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 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 9.5d yr-1 period, resulting in nutrient input/output rates an order of magnitude greater than during non-typhoon period. 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.

2013-04-01

262

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

263

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

264

Assessing Impacts of Global Warming on Tropical Cyclone Tracks  

NASA Technical Reports Server (NTRS)

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

Wu, Li-Guang; Wang, Bin

2003-01-01

265

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

266

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

E-print Network

Impact of Tropical Cyclones on the Heat Budget of the South Pacific Ocean S. JULLIEN,* C. E. MENKES cyclones (TCs) in the South Pacific convergence zone through a complete ocean heat budget. The TC impact by a mesoscale atmospheric model solution in which extreme winds associated with cyclones are either maintained

267

The NOW regional coupled model: Application to the tropical Indian Ocean climate and tropical cyclone activity  

NASA Astrophysics Data System (ADS)

paper presents the NOW regional coupled ocean-atmosphere model built from the NEMO ocean and WRF atmospheric numerical models. This model is applied to the tropical Indian Ocean, with the oceanic and atmospheric components sharing a common horizontal grid. Long experiments are performed over the 1990-2009 period using the Betts-Miller-Janjic (BMJ) and Kain-Fritsch (KF) cumulus parameterizations. Both simulations produce a realistic distribution of seasonal rainfall and a realistic northward seasonal migration of monsoon rainfall over the Indian subcontinent. At subseasonal time scales, the model reasonably reproduces summer monsoon active and break phases, although with underestimated rainfall and surface wind signals. Its relatively high resolution results in realistic spatial and seasonal distributions of tropical cyclones, but it fails to reproduce the strongest observed cyclone categories. At interannual time scales, the model reproduces the observed variability associated with the Indian Ocean Dipole (IOD) and the delayed basin-wide warming/cooling induced by the El Nio Southern Oscillation (ENSO). The timing of IOD occurrence in the model generally matches that of the observed events, confirming the influence of ENSO on the IOD development (through the effect of lateral boundary conditions in our simulations). Although the KF and BMJ simulations share a lot in common, KF strongly overestimates rainfall at all time scales. KF also overestimates the number of simulated cyclones by a factor two, while simulating stronger events (up to 55 m s-1) compared to BMJ (up to 40 m s-1). These results could be related to an overly active cumulus parameterization in KF.

Samson, G.; Masson, S.; Lengaigne, M.; Keerthi, M. G.; Vialard, J.; Pous, S.; Madec, G.; Jourdain, N. C.; Jullien, S.; Menkes, C.; Marchesiello, P.

2014-09-01

268

Tropical cyclones and polar lows: Velocity, size, and energy scales, and relation to the 26C cyclone origin criteria  

Microsoft Academic Search

The goal of this paper is to quantitatively formulate some necessary conditions for the development of intense atmospheric\\u000a vortices. Specifically, these criteria are discussed for tropical cyclones (TC) and polar lows (PL) by using bulk formulas\\u000a for fluxes of momentum, sensible heating, and latent heating between the ocean and the atmosphere. The velocity scale is used\\u000a in two forms: (1)

G. S. Golitsyn; A. M. Obukhov

2009-01-01

269

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

PubMed

A recently developed technique for simulating large [O(10(4))] numbers of tropical cyclones in climate states described by global gridded data is applied to simulations of historical and future climate states simulated by six Coupled Model Intercomparison Project 5 (CMIP5) global climate models. Tropical cyclones downscaled from the climate of the period 1950-2005 are compared with those of the 21st century in simulations that stipulate that the radiative forcing from greenhouse gases increases by over preindustrial values. In contrast to storms that appear explicitly in most global models, the frequency of downscaled tropical cyclones increases during the 21st century in most locations. The intensity of such storms, as measured by their maximum wind speeds, also increases, in agreement with previous results. Increases in tropical cyclone activity are most prominent in the western North Pacific, but are evident in other regions except for the southwestern Pacific. The increased frequency of events is consistent with increases in a genesis potential index based on monthly mean global model output. These results are compared and contrasted with other inferences concerning the effect of global warming on tropical cyclones. PMID:23836646

Emanuel, Kerry A

2013-07-23

270

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

NASA Technical Reports Server (NTRS)

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

Wilson, Robert M.

2009-01-01

271

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

PubMed Central

A recently developed technique for simulating large [O(104)] numbers of tropical cyclones in climate states described by global gridded data is applied to simulations of historical and future climate states simulated by six Coupled Model Intercomparison Project 5 (CMIP5) global climate models. Tropical cyclones downscaled from the climate of the period 19502005 are compared with those of the 21st century in simulations that stipulate that the radiative forcing from greenhouse gases increases by over preindustrial values. In contrast to storms that appear explicitly in most global models, the frequency of downscaled tropical cyclones increases during the 21st century in most locations. The intensity of such storms, as measured by their maximum wind speeds, also increases, in agreement with previous results. Increases in tropical cyclone activity are most prominent in the western North Pacific, but are evident in other regions except for the southwestern Pacific. The increased frequency of events is consistent with increases in a genesis potential index based on monthly mean global model output. These results are compared and contrasted with other inferences concerning the effect of global warming on tropical cyclones. PMID:23836646

Emanuel, Kerry A.

2013-01-01

272

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

273

An observational study of multiple tropical cyclone events in the western north Pacific  

NASA Astrophysics Data System (ADS)

Best-track and NCEP/NCAR reanalysis data are used to study the statistics of multiple cyclone events (MCEs), in which one tropical cyclone (the `daughter') forms to the east of another extant TC (the `mother') during the mother's lifetime, in the western north Pacific. It is found that approximately 30% of all tropical cyclones become mothers, and that MCEs occur relatively more frequently in the early and late season than the peak season. Composite differences in large-scale conditions between MCEs and events in which a daughter does not form show that MCEs are favoured by easterly vertical shear and cyclonic low-level horizontal shear. These findings are broadly consistent with (though they do not prove) the hypothesis that Rossby wave radiation is an important mechanism in a significant fraction of MCE events and that the radiation is governed by linear stationary wave dynamics.

Krouse, Kyle D.; Sobel, Adam H.

2010-05-01

274

New evidence for enhanced ocean primary production triggered by tropical cyclone  

Microsoft Academic Search

New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long-speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai-Tak passed over the South China Sea (SCS). During its short 3-day stay, Kai-Tak triggered an average 30-fold increase in surface chlorophyll-a concentration. The estimated carbon fixation resulting

I. Lin; W. Timothy Liu; Chun-Chieh Wu; George T. F. Wong; Chuanmin Hu; Zhiqiang Chen; Wen-Der Liang; Yih Yang; Kon-Kee Liu

2003-01-01

275

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

276

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

277

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

278

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

E-print Network

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

Wang, Yuqing

279

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 98, NO. D12, PAGES 23,245-23,263, DECEMBER 20, 1993 Numerical Simulations of Tropical Cyclone-Ocean Interaction  

E-print Network

Simulations of Tropical Cyclone-Ocean Interaction With a High-Resolution Coupled Model MORRISA. BENDER,1ISAACGINIS,2,3AND YOSHIO KURIHARA1 The tropical cyclone-ocean interaction was investigated using a high-resolution tropical cyclone ocean coupled model. The model design consisted of the NOAA Geophysical Fluid Dynamics

Rhode Island, University of

280

IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING, VOL. 4, NO. 4, DECEMBER 2011 857 Determining Selected Tropical Cyclone  

E-print Network

, DECEMBER 2011 857 Determining Selected Tropical Cyclone Characteristics Using QuikSCAT's Ultra be used to help estimate tropical cyclone (TC) charac- teristics such as TC center and wind radii wind radii. Index Terms--Atmospheric modeling, radar remote sensing, sea surface, tropical cyclones. I

Long, David G.

281

Modulation of North Pacific Tropical Cyclone Activity by Three Phases of ENSO HYE-MI KIM, PETER J. WEBSTER, AND JUDITH A. CURRY  

E-print Network

Modulation of North Pacific Tropical Cyclone Activity by Three Phases of ENSO HYE-MI KIM, PETER J impacts on tropical cyclone (TC) activity over the North Pacific by differential modulation of both local of the EPW. 1. Introduction The influence of the El Nin~o­Southern Oscillation (ENSO) on tropical cyclone (TC

Webster, Peter J.

282

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

­1855, October 2011 A An investigation of rotational influences on tropical-cyclone size and intensity Roger K the rotational constraint on the intensity and size of a tropical cyclones using a minimal, three-layer, axisymmetric tropical-cyclone model. In the first of two sets of experiments, the same initial baroclinic

Smith, Roger K.

283

The present state of knowledge regarding tropical cyclone activity in various ocean basins and the El NioSouthern Oscillation phenomenon is reviewed in  

E-print Network

The present state of knowledge regarding tropical cyclone activity in various ocean basins Pacific, and the North Atlantic. Following a description of the ENSO phenomenon, tropical cyclone activity. For the western North Pacific, the pronounced change in tropical cyclone activity due to warm ENSO is the eastward

Hawai'i at Manoa, University of

284

Extended Prediction of North Indian Ocean Tropical Cyclones James I. Belanger*, Peter J. Webster, Judith A. Curry, and Mark T. Jelinek  

E-print Network

Extended Prediction of North Indian Ocean Tropical Cyclones James I. Belanger*, Peter J. Webster Ensemble Prediction System (VarEPS) for tropical cyclones (TCs) in the3 North Indian Ocean (NIO) including: tropical cyclone genesis, pre-genesis and post-genesis track4 and intensity projections and regional

Webster, Peter J.

285

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

Although tropical cyclones are still not fully understood, Professor Nick Shay was responsible as it intensifies or weakens. Much of your work focuses on the study of hurricanes and tropical cyclones. What can. This is indeed a global problem as the oceans cover 71 per cent of the surface and tropical cyclones form over

Miami, University of

286

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

287

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

288

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

289

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 0.33C; 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

290

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

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 Discovery Channel « back Global Warming and Tropical Cyclones: a Vicious Cycle? Emily Sohn, Discovery News May 14, 2009 -- Global warming can change storm

Romps, David M.

291

TRMM Flyby of Tropical Cyclone Narelle - Duration: 0:15.  

NASA Video Gallery

This animated, 3-D flyby of Major Cyclone Narelle was created using data on Jan. 11, from NASA's TRMM satellite. Narelle's wind speeds were near 132 mph. A few thunderstorm towers in Narelle's eye ...

292

Tropical Cyclone Bejisa Near Madagascar - Duration: 0:13.  

NASA Video Gallery

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

293

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

294

Environmental Disaster and Economic Change: Do tropical cyclones have permanent effects on economic growth and structure?  

NASA Astrophysics Data System (ADS)

Natural disasters have important, often devastating, effects upon economic growth and well-being. Due to this, disasters have become an active area of recent research and policy attention. However, much of this research has been narrowly focused, relying on anecdotal evidence and aggregated data to support conclusions about disaster impacts in the short-term. Employing a new global data set of tropical cyclone exposure from 1960 to 2008, we investigate in greater detail whether permanent changes in economic performance and structure can result from these extreme events in some cases. Our macro-economic analyses use the World Development Indicator dataset and have shown promising results: there are dramatic long-term economic transformations associated with tropical cyclones across a number of countries and industries. This effect is most clearly seen in Small Island Developing States (SIDS) and some countries in Latin America, where negative changes in long-term growth trends are observed in the years following a large tropical cyclone. In many economies with a high exposure to tropical cyclone damage, there are noticeable structural changes within the economy. The impacts of disasters might be expressed through various economic and social channels, through direct loss of lives and infrastructure damage; for instance, the destruction of infrastructure such as ports may damage export opportunities where replacement capital is not readily available. These structural changes may have far-reaching implications for economic growth and welfare. Larger nations subjected to the impacts of tropical cyclones are thought to be able to relocate economically important activities that are damaged by cyclones, and so long-term trend changes are not observed, even for events that cause a large immediate decrease in national productivity. By investigating in a more rigorous fashion the hypothesis that the environment triggers these permanent economic changes, our work has implications for the conceptual foundations of both economic theory and sustainable development.

Jina, A.; von der Goltz, J.; Hsiang, S. M.

2011-12-01

295

Variability in tropical cyclone heat potential over the Southwest Indian Ocean  

NASA Astrophysics Data System (ADS)

Tropical cyclone heat potential (TCHP) has been proposed as being important for hurricane and typhoon intensity. Here, a climatology of TCHP is developed for the Southwest Indian Ocean, a basin that experiences on average 11-12 tropical cyclones per year, many of which impact on Mauritius, Reunion and Madagascar, and Mozambique. SODA data and a regional ocean model forced with the GFDL-CORE v.2b reanalysis winds and heat fluxes are used to derive TCHP values during the 1948-2007 period. The results indicate that TCHP increases through the austral summer, peaking in March. Values of TCHP above 40 kJ cm-2, suggested as the minimum needed for tropical cyclone intensification, are still present in the northern Mozambique Channel in May. A time series of TCHP spatially averaged over the Seychelles-Chagos thermocline ridge (SCTR), an important area for tropical cyclones, is presented. The model time series, which agrees well with XBT-based observations (r = 0.82, p = 0.01), shows considerable interannual variability overlaying an upward tendency that matches with an observed increase in severe tropical cyclone days in the Southwest Indian Ocean. Although an increase in severe storms is seen during 1997-2007, the increasing TCHP tendency time series after 1997 coincides with a decrease in total cyclone numbers, a mismatch that is ascribed to increased atmospheric anticyclonicity over the basin. Seasons of increased (decreased) TCHP over the SCTR appear to be associated with dry (wet) conditions over certain areas of southern and East Africa and are linked with changes in zonal wind and vertical motion in the midtroposphere.

Malan, N.; Reason, C. J. C.; Loveday, B. R.

2013-12-01

296

Condensed Water in Tropical Cyclone "Oliver", 8 February 1993  

NASA Technical Reports Server (NTRS)

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 x 10(exp 3)/cu m, the geometric mean diameter D(sub g) = 0.5-0.7 mm, and the liquid water content 0.7-1.9 g m(exp-3). The largest particles anywhere in the cloud, dominated by fused dendrites at concentrations similar to that of raindrops (2.5 x 10(exp 3) m(exp -3)) but a higher condensed water content(5.4 g/cu m 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 x 10(exp 4)/cu m, smallest size (D(sub g) = 0.3-0.4 mm), largest surface area (up to 2.6 x 10 (exp 2) sq cm/cu m at 0.4- 1.0 g/cu m 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) and backscatter (0.8/sr/km) 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.

1995-01-01

297

Tropical cyclones and the flood hydrology of Puerto Rico  

USGS Publications Warehouse

Some of the largest unit discharge flood peaks in the stream gaging records of the U.S. Geological Survey (USGS) have occurred in Puerto Rico. Many of these flood peaks are associated with tropical cyclones. Hurricane Georges, which passed directly over the island on 21-22 September 1998, produced record flood peaks at numerous USGS stations in Puerto Rico. The hydrology and hydrometeorology of extreme flood response in Puerto Rico are examined through analyses of rainfall, based on Weather Surveillance Radar - 1988 Doppler (WSR-88D) radar reflectivity observations and USGS rain gage observations and discharge from USGS stream gaging stations. Peak rainfall accumulations of more than 700 mm occurred in the central mountain region of the island. The largest unit discharge flood peaks, however, were located in the eastern portion of the island in areas with smaller storm total rainfall accumulations but markedly larger rainfall rates at 5-60 min timescale. Orographic precipitation mechanisms played an important role in rainfall distribution over the island of Puerto Rico. Amplification of rainfall accumulations was associated with areas of upslope motion. Elevated low-level cloud water content in regions of upslope motion played an important role in the maximum rainfall accumulations in the central mountain region of Puerto Rico. The largest unit discharge flood peaks, however, were produced by a decaying eye wall mesovortex, which resulted in a 30-45 min period of extreme rainfall rates over the eastern portion of the island. This storm element was responsible for the record flood peak of the Rio Grande de Lo??iza. The role of terrain in development and evolution of the eye wall mesovortex is unclear but is of fundamental importance for assessing extreme flood response from the storm. Hydrologic response is examined through analyses of rainfall and discharge from five pairs of drainage basins, extending from east to west over the island. These analyses point to the importance of short-term rainfall rates for extreme flood response. The hydrologic response of Puerto Rico is compared with two other extreme flood environments, the central Appalachians and Edwards Plateau of Texas. These analyses suggest that the high rainfall environment of Puerto Rico is linked to the development of a hydraulically efficient drainage system. Copyright 2005 by the American Geophysical Union.

Smith, J.A.; Sturdevant-Rees, P.; Baeck, M.L.; Larsen, M.C.

2005-01-01

298

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

299

The Impact of Canonical and Non-canonical El Nio on Atlantic Tropical Cyclone Activity: High-resolution Tropical Channel Model Simulations  

NASA Astrophysics Data System (ADS)

Tropical Pacific sea surface temperature (SST) variability during the El Nio-Southern Oscillation (ENSO) influences seasonal Atlantic tropical cyclone activity by modulating vertical wind shear and tropospheric temperature in the tropical Atlantic, with warmer than average SST during El Nio suppressing Atlantic tropical cyclones. The location of maximum SST warming during El Nio varies from the East Pacific (canonical) to Central Pacific (non-canonical/Modoki). This study investigates how the location and magnitude of maximum tropical Pacific warming impacts Atlantic tropical cyclones, and through what mechanisms. Climate simulations are performed to supplement observationally based studies, which yield conflicting results and rely on a relatively short data record that is complicated by factors other than ENSO, such as Atlantic SST variability. The simulations are run with the Weather Research and Forecasting (WRF) model configured as a tropical channel model at a relatively fine horizontal resolution of 27 km compared to the current generation of global climate models that typically use a 50 - 100 km grid. Monthly climatological SST is prescribed in the control simulation, and mechanistic experiments are forced by tropical Pacific SST patterns characteristic of Central Pacific and East Pacific El Nio. Seasonal accumulated cyclone energy is used to evaluate the response in Atlantic tropical cyclone activity to Central and East Pacific El Nio, and the response in atmospheric conditions relevant for tropical cyclones is diagnosed using a genesis potential index.

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

2013-12-01

300

A comparison of all tropical cyclones with intensity at or greater than tropical storm strength (34 kts) between the combination of the data from RSMC-Miami (NHC/HURDAT) and JTWC versus the IBTrACS data set.  

E-print Network

A comparison of all tropical cyclones with intensity at or greater than tropical storm strength (34 information from twelve tropical cyclone· datasets; Checks the quality of storm inventories, positions and wind speed· observations; Contains the most complete set of cyclones available;· Performs semi

301

Tropical prediction using dynamical nudging, satellite-defined convective heat sources, and a cyclone bogus  

SciTech Connect

Some notable problems in tropical prediction have been (1) the sensitivity to, and inaccuracies in, the four-dimensional structure of parameterized convective heating, (2) the inability of conventional data networks to adequately define tropical cyclone structures, and (3) the so-called spinup problem of numerical models. To help overcome some of these deficiencies, a diabatic nudging scheme has been developed for the Bureau of Meteorology Research Center limited-area tropical prediction system. A target analysis for the nudging is first obtained from statistical interpolation of all observational data, using, as first-guess field, output from a global assimilation and prediction system. Tropical cyclones are optionally inserted via bogus wind observations. From 12 or 24 h prior to the base time of the forecast, the prediction model is nudged toward the target analysis. During nudging the 'observationally reliable' rotational wind component is preserved and the heating from the Kuo scheme is replaced by a heating function determined from 6-h satellite-observed cloud-top temperatures. The system introduces realistic tropical cyclone structures into the initial condition, defines a vertical-motion field consistent with the satellite cloud imagery, enhances rainfall rates during the early hours of the forecast, reduces the occurrence of spurious rainfall maxima, and improves mass-wind balance and retention of cyclone circulations during the model integration. Examples of system performance from enhanced observational datasets and from real-time forecasting are presented. Encouraging results for short-term prediction of both tropical cyclone behavior and rainfall events are documented. 29 refs.

Davidson, N.E.; Puri, K. (Research Centre, Melbourne (Australia))

1992-11-01

302

MST radar observations of short-period gravity wave during overhead tropical cyclone  

NASA Astrophysics Data System (ADS)

Short-period gravity waves associated with the passage of tropical cyclone using mesosphere-stratosphere-troposphere (MST) radar located at Gadanki (13.5N, 79.2E) has been discussed. The observed stratospheric gravity wave is found to have a periodicity of 42 min, vertical and horizontal wavelength of 3.5 km and 14 km, respectively. Maximum amplitude of gravity wave is observed in the upper troposphere and lower stratosphere (UTLS) region due to which periodic updrafts and downdrafts are observed. This weakens the stability of tropopause, which is observed in radar signal-to-noise ratio (SNR). The enhancement of vertical momentum flux of order -0.6 m2/s2 observed in the lower stratosphere is attributed to the cyclone generated gravity waves. The obstacle effect is found to be the generative mechanism for the observed gravity waves associated with the tropical cyclone.

Das, Siddarth Shankar; Uma, K. N.; Das, Subrata Kumar

2012-04-01

303

Effects of tropical cyclone waves on ecological and geomorphological structures on the Great Barrier Reef  

NASA Astrophysics Data System (ADS)

Damage to coral reefs caused by Tropical Cyclone Ivor (March 1990) on 46 sites over 150 km of the Great Barrier Reef was patchily distributed within 50 km of the path, while at distances 50km from the eye, it was uniformly low. These distances suggest that local wind-generated waves, not ocean swells, may be the major cause of destruction. Wind component incident on each site, UN, was therefore hindcast from tropical cyclone circulation models. The sum of hourly UN explained about 82% of the variance in an index of total damage and 90% of the destruction of a veneer of dense coral growth up to 1.5 m in thickness. This correlation is consistent with an "attrition" model, in which cyclone waves exfoliate reefs, chunk by chunk, over the period of storm waves.

Done, T. J.

1992-07-01

304

An Estimate of North Atlantic Basin Tropical Cyclone Activity for 2008  

NASA Technical Reports Server (NTRS)

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

Wilson, Robert M.

2008-01-01

305

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

306

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.

307

EFFECTIVENESS OF QUIKSCAT'S ULTRA-HIGH RESOLUTION IMAGES IN DETERMINING TROPICAL CYCLONE EYE LOCATION  

E-print Network

EFFECTIVENESS OF QUIKSCAT'S ULTRA-HIGH RESOLUTION IMAGES IN DETERMINING TROPICAL CYCLONE EYE be enhanced to yield a 2.5km ultra-high resolution (UHR) product that can be used to identify hurricane eye centers more accurately. A comparison is made between the ana- lyst's choice of eye location based on UHR

Long, David G.

308

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

Microsoft Academic Search

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

Eric Walter Uhlhorn

2008-01-01

309

Frictionally Controlled, Thermally Driven Circulations in a Circular Vortex with Application to Tropical Cyclones  

Microsoft Academic Search

Based upon an argument by Charney and Eliassen, a tropical cyclone is envisaged as a combined system of a quasi-gradient circular vortex and a slow meridional circulation. The driving mechanism of this circulation is the release of latent heat, which is in turn controlled by the mass convergence in the surface boundary layer. A consistent set of dynamic equations is

Yoshimitsu Ogura

1964-01-01

310

Satellite observations of variations in tropical cyclone convection caused by upper-tropospheric troughs  

NASA Technical Reports Server (NTRS)

Satellite observations and numerical model results have been used to study the relationship between upper-tropospheric forcing and the oscillation of convection of tropical cyclones Florence (1988) and Irene (1981) during their mature stage over open warm oceans (SST greater than or equal to 26 C). It is suggested that the initiation and maintenance of intense convective outbreaks in tropical cyclones are related to the channeling and strengthening of their outflow by upper-tropospheric troughs. It is possible to enhance the convection in response to the outflow jet-induced import of eddy relative angular momentum and ascending motion associated with the thermally direct circulation. Both Florence and Irene are found to intensify after the onset of these convective episodes. It is also suggested that the cessation in the convection of the two tropical cyclones occurs when the upper-tropospheric troughs move near or over the tropical cyclones, resulting in the weakening of their outflow and the entrainment of dry upper-tropospheric air into their inner core.

Rodgers, Edward B.; Chang, Simon W.; Stout, John; Steranka, Joseph; Shi, Jainn-Jong

1991-01-01

311

A Simple Empirical Model for Predicting the Decay of Tropical Cyclone Winds after Landfall  

Microsoft Academic Search

An empirical model for predicting the maximum wind of landfalling tropical cyclones is developed. The model is based upon the observation that the wind speed decay rate after landfall is proportional to the wind speed. Observations also indicate that the wind speed decays to a small, but nonzero, background wind speed. With these assumptions, the wind speed is determined from

John Kaplan; Mark Demaria

1995-01-01

312

Real-Time Internet Distribution of Satellite Products for Tropical Cyclone Reconnaissance  

Microsoft Academic Search

Tropical cyclone (TC) monitoring requires the use of multiple satellites and sensors to accurately assess TC location and intensity. Visible and infrared (vis\\/IR) data provide the bulk of TC information, but upper-level cloud obscurations inherently limit this important dataset during a storm's life cycle. Passive microwave digital data and imagery can provide key storm structural details and offset many of

Jeffrey D. Hawkins; Thomas F. Lee; Joseph Turk; Charles Sampson; John Kent; Kim Richardson

2001-01-01

313

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

314

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.

315

10A.7 CLUSTER ANALYSIS OF WESTERN NORTH PACIFIC TROPICAL CYCLONE TRACKS Suzana J. Camargo  

E-print Network

). The trajectories in cluster A tend to exist and form in the Philippines sea and especially the South China Sea to the Indian Ocean. The genesis region for cluster B is north and east of the Philippines. The dominant and Japan. Tropical cyclones in the western North Pacific occur year round, with a peak in

Smyth, Padhraic

316

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

317

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

318

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

Microsoft Academic Search

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

D. Mardhekar

2010-01-01

319

Tropical cyclone genesis efficiency: mid-level versus bottom vortex Xuyang Ge and Tim Li  

E-print Network

1 Tropical cyclone genesis efficiency: mid-level versus bottom vortex Xuyang Ge and Tim Li: Dr. Tim Li, Department of Meteorology, University of Hawaii, 2525 Correa Rd., Honolulu, HI 96822. Email: timli@hawaii.edu #12;2 Abstract Cloud resolving Weather Research and Forecasting (WRF) model

Li, Tim

320

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

321

Response of sediment dynamics in the York River Estuary, USA to tropical cyclone Isabel of 2003  

Microsoft Academic Search

Tropical Cyclone Isabel of 2003 generated large storm surge, strong waves, and subsequent river flooding in the York River Estuary, USA during its passage across the Chesapeake Bay region. A 3D model was used to investigate the changes of sediment concentration, sediment flux, and the recovery time of the York River Estuary to its naturally evolved condition without the storm.

Wenping Gong; Jian Shen

2009-01-01

322

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

E-print Network

with tropical cyclones. Present international design codes for wind turbines do not apply to these regions. A 30 of a modern wind turbine is for 20 years and the load cases considered for the structural design average wind speeds, and wind turbines designed for low average wind speeds would be suitable in order

323

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

E-print Network

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

Nolan, David S.

324

The air-sea interface and surface stress under tropical cyclones  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

325

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

Microsoft Academic Search

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

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

2004-01-01

326

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

PubMed

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

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

2014-01-01

327

The air-sea interface and surface stress under tropical cyclones  

PubMed Central

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

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

2014-01-01

328

Current understanding of tropical cyclone structure and intensity changes a review  

Microsoft Academic Search

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

Y. Wang; C.-C. Wu

2004-01-01

329

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

330

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

NASA Astrophysics Data System (ADS)

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

Stern, Daniel; Bryan, George

2014-05-01

331

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

NASA Astrophysics Data System (ADS)

Recent research on the Mississippi margin indicates notable seasonal variation in seabed dynamics. During years with minimal tropical-system activity, sediments initially deposited from late spring to early fall are remobilized by wind-driven currents and wave energy during extra-tropical weather systems in the winter. This research reveals the profound significance of tropical cyclones on Louisiana Shelf sedimentation. The amount of material delivered to and advected across the shelf by recent tropical cyclones is considerably larger than that related to winter storm systems. In Fall 2004, the river-dominated shelf of Louisiana was impacted by three tropical systems in less than a month, including Hurricane Ivan. Ivan, with maximum sustained winds in excess of 74 m s -1 (144 knots) and a minimum measured central pressure of 910 mbar, was the eighth most intense Atlantic hurricane on record at the time. In order to assess the impact these tropical systems had on the continental margin west of the Mississippi delta, seabed samples were collected from box cores in October 2004 and analyzed for particle-reactive radionuclides 234Th, 7Be, and 210Pb. Radiochemical data and observations from X-radiographs indicate event-driven sediment deposits ranged from 4 to 30 cm on the shelf and 2-6 cm in the Mississippi Canyon. These deposits exhibit distinct radiochemical signatures and differ visually and texturally from the underlying sediment. The well-developed physical stratification and graded nature of the deposits observed in core X-radiographs suggests that the sediment could have been deposited from sediment-gravity flows. Inventories of 7Be and 7Be/ 234Th xs ratios reveal this series of cyclones transported considerably more material to the outer shelf and slope than periods of minimal tropical-system activity. When compared to seasonal depositional rates created by winter storms, tropical-cyclone-related event deposits on the middle and outer shelf are up to an order of magnitude greater in thickness. The number and thickness of these event deposits decrease with distance from the delta and suggest that only the most severe tropical systems are likely capable of redistributing significant quantities of sediment to more distal portions of the shelf and slope. These severe-event-driven deposits may account for as much as 75% of the sediment burial budget on decadal time scales within Mississippi Canyon. Higher than average tropical cyclone activity, predicted by the National Hurricane Center over the next decade, may be the major mechanism controlling sediment transport and deposition on the Mississippi River continental shelf and in Mississippi Canyon.

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

2007-08-01

332

Increasing destructiveness of tropical cyclones over the past 30years  

Microsoft Academic Search

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

Kerry Emanuel

2005-01-01

333

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

334

Effect of tropical cyclones on the phytoplankton composition in the oligotrophic tropical waters: Remote sensing observations in the South China Sea  

NASA Astrophysics Data System (ADS)

In the tropical open oceans, strong vertical stratification often prevents the transport of nutrient-rich subsurface waters to the surface mixed layer, and the dominant phytoplankton species are generally pico-sized, such as Prochlorococcus and Synechococcus. Tropical cyclones are a strongly effective forcing to cause a significant elevation of nutrients in the surface mixed layer, and thus to cause the phytoplankton bloom and the shift of phytoplankton community structure. In this study, the cycle of the shift of phytoplankton composition caused by the passing of tropical cyclones was evaluated in the South China Sea, which is an oligotropical tropical ocean located in the western North Pacific and frequent visits of tropical cyclones occur in. By using a recently developed approach applying to the satellite remote sensing data, four phytoplankton groups dominated individually by Prochlorococcus, Synechococcus, haptophytes, and diatoms were determined. We proposed that the phytoplankton composition shifted progressively from the dominance of Prochlorococcus --> Synechococcus --> haptophytes --> diatoms with the passing of tropical cyclones, and then shifted progressively in the reverse direction later as the effect of tropical cyclones was diminished. However, the speed of the shifting may be affected by: the original status of phytoplankton composition, the strength and duration of the tropical cyclones, the season (summer or autumn), and the occurrence of other forcing such as internal waves.

Pan, X.; Wong, G. T.

2012-12-01

335

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

336

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.; Bgue, N.

2014-07-01

337

Feasibility of tropical cyclone intensity estimation using satellite-borne radiometer measurements: An observing system simulation experiment  

E-print Network

This study evaluates the potential of a proposed technique in using satellite-borne radiometer measurements and weather analyses to estimate the intensity of tropical cyclones. This theory shows that intensity is essentially ...

Sieron, Scott B.

338

Changes in number and intensity of world-wide tropical cyclones  

E-print Network

Bayesian statistical models were developed for the number of tropical cyclones and the rate at which these cyclones became hurricanes in the North Atlantic, North and South Indian, and East and West Pacific Oceans. We find that there is small probability that the number of cyclones has increased in the past thirty years. The rate at which these storms become hurricanes appears to be constant. The rate at which hurricanes evolve into category 4 and higher major storms does appear to have increased. We also investigate storm intensity by measuring the distribution of individual storm lifetime in days, storm track length, and Emanuel's power dissiptation index. We find little evidence that, overall, the mean of the distribution of individual storm intensity is changing through time, but the variability of the distribution has increased. The cold tongue index and the North Atlantic oscillation index were found to be strongly associated with storm quality in the Western, and to a smaller extent, the Eastern Pacifi...

Briggs, W M

2007-01-01

339

On the changes in number and intensity of North Atlantic tropical cyclones  

E-print Network

Bayesian statistical models were developed for the number of tropical cyclones and the rate at which these cyclones became hurricanes in the North Atlantic. We find that, controlling for the cold tongue index and the North Atlantic oscillation index, there is high probability that the number of cyclones has increased in the past thirty years; but the rate at which these storms become hurricanes appears to be constant. We also investigate storm intensity by measuring the distribution of individual storm lifetime in days, storm track length, and Emanuel's power dissiptation index. We find little evidence that the distribution of individual storm intensity is changing through time. Any increase in cumulative yearly storm intensity and potential destructiveness, therefore, is due to the increasing number of storms and not due to any increase in the intensity of individual storms.

Briggs, W M

2007-01-01

340

The relationship between satellite measured convective bursts and tropical cyclone intensification  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

341

Electric Field Profiles over Hurricanes, Tropical Cyclones, and Thunderstorms with an Instrumented ER-2 Aircraft  

NASA Technical Reports Server (NTRS)

Over the past several years, we have flown a set of calibrated electric field meters (FMs) on the NASA high altitude ER-2 aircraft over oceanic and landbased storms in a number of locations. These included tropical oceanic cyclones and hurricanes in the Caribbean and Atlantic ocean during the Third and Fourth Convection And Moisture EXperiment (CAMEX-3,1998; CAMEX-4, 2001), thunderstorms in Florida during the TExas FLorida UNderflight (TEFLUN, 1998) experiment, tropical thunderstorms in Brazil during the Tropical Rainfall Measuring Mission - Large Scale Biosphere-Atmosphere Experiment in Amazonia (TRMM LBA, 1999), and finally, hurricanes and tropical cyclones in the Caribbean and Western Pacific and thunderstorms in Central America during the Tropical Cloud Systems and Processes (TCSP, 2005) mission. Between these various missions we have well over 50 sorties that provide a unique insights on the different electrical environment, evolution and activity occurring in and around these various types of storms. In general, the electric fields over the tropical oceanic storms and hurricanes were less than a few kilovolts per meter at the ER-2 altitude, while the lightning rates were low. Land-based thunderstorms often produced high lightning activity and correspondingly higher electric fields.

Mach, Doug M.; Blakeslee, Richard J.; Bateman, Monte G.; Bailey, Jeff C.

2007-01-01

342

Analysis of Tropical Cyclones and Tropical Waves using the Parallel Ensemble Empirical Model Decomposition (EEMD) Method  

NASA Astrophysics Data System (ADS)

In this study, we discuss the parallel implementation in the ensemble empirical mode decomposition (EMD, Huang et al., 1998; Wu et al., 2009) and its application to the analysis of tropical waves and tropical cyclones (TCs). Recent studies with high-resolution model simulations and satellite data have shown a potential for improving our understanding of TC formation and thus extending the lead time of TC genesis prediction. It was hypothesized that improved predictability of TC formation can be achieved by improving hierarchical scale interactions of a TC and its environmental flows such as different kind of tropical waves (Shen et al., 2010a,b;2012a,b) and/or MJOs. To verify this hypothesis, it is crucial to quantitatively examine the TC genesis processes that accompany downscaling (from large-scale events) and upscaling processes (from small-scale events), and their subsequent non-linear interactions. As these processes are non-linear and non-stationary per se, the original EMD or ensemble EMD (EEMD) becomes a natural choice for performing such analyses. The EMD decomposes one set of observation data into the so-called intrinsic mode functions (IMFs). In comparison, the EEMD deals with an ensemble of data sets, each of which includes the original observation data and finite amplitude white noise, and then applies an ensemble average to obtain the final IMFs. The EEMD was first developed by Wu et al. (2009) to overcome the scale (or mode) mixing problem that may appear in the original EMD. It has been shown that the decomposed mean IMFs stay within the natural filter period windows, significantly reducing the chance of scale mixing while still preserving dyadic property. Depending on the required accuracy of the decomposed IMFs, typical ensemble members are about 200~400 or higher. As the required computational resources are linearly proportional to the number of ensemble trials, it becomes important to improve the performance of the EEMD algorithm to reduce time to solution. Thus, a hybrid OpenMP-MPI parallelism is implemented into the EEMD. In this talk, we will discuss the design of parallelism and present preliminary results with the parallel EEMD. At the end, we will present how the parallel EEMD will be integrated into the multiscale analysis package (MAP) with three-level parallelism which can efficiently process massive volume of global analysis data.

Shen, B.; Wu, Z.; Cheung, S.

2012-12-01

343

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

344

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

345

Lower-stratospheric/upper-tropospheric exchange processes associated with tropical cyclones as observed by TOMS  

NASA Technical Reports Server (NTRS)

Total ozone associated with western Atlantic and Pacific tropical cyclones at various stages of development were analyzed for the purpose of monitoring storm intensity and/or intensity changes. The analysis is based on total ozone measurements from the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS). Since ozone may be considered a passive tracer in the lower stratosphere and the ozone gradients are strongest just above the tropopause, fluctuations of total ozone are due to variations in tropopause height and/or changes in concentration within the column caused by vertical and horizontal advection. In the subtropical northern Pacific during August and September 1981, a negative correlation greater than 0.60 was found between upper-tropospheric geopotential heights near the tropopause level and total ozone. Preliminary results suggest that TOMS can be used to resolve the upper-troposphere structure in and around tropical cyclones and can provide an indication of those processes that help to intensify and maintain these storms.

Rodgers, Edward B.

1987-01-01

346

Safe-economical route model of a ship to avoid tropical cyclones using dynamic forecast environment  

NASA Astrophysics Data System (ADS)

In heavy sea conditions related to tropical cyclones (TCs), losses to shipping caused by capsizing are greater than other kinds of accidents. Therefore, it is important to consider capsizing risk in the algorithms used to generate safe-economic routes that avoid tropical cyclones (RATC). A safe-economic routing and assessment model for RATC, based on a dynamic forecasting environment, is presented in this paper. In the proposed model, a ship's risk is quantified using its capsizing probability caused by heavy wave conditions. Forecasting errors in the numerical models are considered in the ship risk assessment according to their distribution characteristics. A case study shows that: the economic cost of RATCs is associated not only to the ship's speed, but also to the acceptable capsizing probability which is related with the ship's characteristic and the cargo loading condition. Case study results demonstrate that the optimal routes obtained from the model proposed in this paper are superior to those produced by traditional methods.

Wu, L.; Wen, Y.; Wu, D.; Zhang, J.; Xiao, C.

2014-08-01

347

Sensitivities of Tropical Cyclones to Surface Friction and the Coriolis Parameter in a 2-D Cloud-Resolving Model  

NASA Technical Reports Server (NTRS)

The sensitivities to surface friction and the Coriolis parameter in tropical cyclogenesis are studied using an axisymmetric version of the Goddard cloud ensemble model. Our experiments demonstrate that tropical cyclogenesis can still occur without surface friction. However, the resulting tropical cyclone has very unrealistic structure. Surface friction plays an important role of giving the tropical cyclones their observed smaller size and diminished intensity. Sensitivity of the cyclogenesis process to surface friction. in terms of kinetic energy growth, has different signs in different phases of the tropical cyclone. Contrary to the notion of Ekman pumping efficiency, which implies a preference for the highest Coriolis parameter in the growth rate if all other parameters are unchanged, our experiments show no such preference.

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

2002-01-01

348

Structure of a Tropical Cyclone Developed in a Three-Dimensional Numerical Simulation Model  

Microsoft Academic Search

A three-dimensional, 11-level, primitive equation model has been constructed for a simulation study of tropical cyclones. The model has four levels in the boundary layer and its 7070 variable grid mesh encloses a 4000-km square domain with a 20-km resolution near the center. Details of the model, including the parameterization scheme for the subgrid-scale diffusion and convection processes, are described.A

Yoshio Kurihara; Robert E. Tuleya

1974-01-01

349

The Interannual Variability in the Genesis Location of Tropical Cyclones in the Northwest Pacific  

Microsoft Academic Search

Variations in the seasonal mean (July-October) genesis positions of tropical cyclones (TCs) in the western North Pacific associated with variations in the large-scale atmospheric circulation are investigated. Analysis shows considerable interannual variability in the seasonal TC mean genesis positions (MGPs) during the 1979-99 period. The variability is shown to be related to the 200-850-hPa vertical wind shear, the west Pacific

Hsin Hsing Chia; C. F. Ropelewski

2002-01-01

350

Monitoring and predicting tropical cyclone movement using geosynchronous satellite remote sensing techniques  

NASA Technical Reports Server (NTRS)

Data collected on special hurricane days by the VISSR Atmospheric Sounder (VAS) instrument flown on a satellite in 1981 and 1982 were studied for their usefulness in forecasting motion of hurricanes. The retrieved constant pressure heights for the 500-mb surface provided the basis for reasonable forecasts of 24 hour hurricane motion. The conclusions are illustrated with examples from Hurricane Harvey (1981) and Hurricane Irene (1981). Recommendations are made for future use of the VAS type instruments for tropical cyclone forecasting.

Dubach, L. (editor); Gentry, R. Cecil

1986-01-01

351

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

352

Analysis of tropical cyclone dynamics in two models of different complexity  

NASA Astrophysics Data System (ADS)

Tropical cyclone dynamics and its sensitivity to several climatological parameters is investigated within the axisymmetric high-resolution cloud model HURMOD on and by means of a conceptual tropical cyclone (TC) model. Within the conceptual model, the TC is divided into three regions, the eye, eyewall and ambient region. The conceptual model forms a low order dynamical system of three ordinary differential equations. These are based on entropy budget equations comprising processes of surface enthalpy transfer, entropy advection, convection and radiative cooling. For tropical ocean parameter settings, the system possesses four non-trivial steady state solutions when the sea surface temperature (SST) is above a critical value. Two steady states are unstable while the two remaining states are stable. Bifurcation diagrams provide an explanation why only finite-amplitude perturbations above a critical SST can transform into TCs. Besides SST, relative humidity of the ambient region forms an important model parameter as it highly affects the entrainment of low entropy air into the inflow region of the TC. The surfaces that describe equilibria as a function of SST and relative humidity reveal a cusp-catastrophe where the two non-trivial equilibria split into four. Within the model regime of four equilibria, cyclogenesis becomes very unlikely due to the repelling and attracting effects of the two additional equilibria. It is tested, whether the qualitative behaviour observed in the box-model simulations is reproducible in the axisymmetric cloud model HURMOD by variation of the initial vortex strength and climatological parameters in analogy to conceptual model experiments. It is shown that an attractor associated with a tropical cyclone exists in HURMOD when a warm-rain micro-physical scheme is applied. By varying SST, the reference temperature profile and relative humidity of the reference state, we find a tropical cyclone branch and a bifurcation in HURMOD similar to those detected in the low order box-model. The results evince the relevance of approaching the dynamics of tropical cyclone formation and its maximum potential intensity (MPI) using a hierarchy of models of different complexity.

Schnemann, D. B.; Frisius, T.

2012-04-01

353

Seasonal Rates for Atlantic Basin Tropical Cyclones During the Present Epoch  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

354

Can Foraminifera be used to Identify Storm Deposits in Shallow-Water Tropical Reef Settings?: Examining the Impact of Cyclone Hamish on the Foraminiferal Assemblages of Heron Island, Great Barrier Reef, Australia  

NASA Astrophysics Data System (ADS)

Foraminifera (marine microfossils) represent a valuable tool in identifying significant storm events in the geological past. Much of the previous work in this area however, has concentrated on temperate settings and marsh deposits. Little work has focused on tropical marine settings and no studies have looked to identify distinct foraminiferal assemblages associated with cyclone events in tropical reef settings in the South-West Pacific. In April 2008, samples were collected from the reef flat surrounding Heron Island as part of a study of foraminiferal biodiversity. On March 9th 2009, Cyclone Hamish, a Category 5 cyclone and the most significant cyclone event, in terms of impact and damage, to occur in the southern Great Barrier Reef region in over 30 years, passed in close proximity to Heron Island. With a pre-cyclone baseline collected less than 1 year previous, this presented an ideal opportunity to recollect, with the aim to determining if a discernable cyclone generated deposit could be identified. A distinct difference in composition or character of the foraminiferal assemblage identified in the pre- and post-cyclone samples could be directly attributed to the cyclone and would represent a fingerprint assemblage. This would provide a mechanism for determining cyclonic activity in the sub-recent and geological past for both the Great Barrier Reef region as well as throughout the South-west Pacific. Analysis of the total foraminiferal assemblage in the two sample lots reveals little difference between the pre- and post-cyclone assemblage. In both cases, the assemblage is dominated by the same two epiphytic taxa, Calcarina hispida Brady and Baculogypsina sphaerulata (Parker and Jones). No taxa are restricted to either pre- or post-cyclone samples and the post-cyclone assemblage bears no resemblance to the assemblage recovered from samples collected in the inter-reef channels. This suggests that the cyclone is only mobilising and redepositing material on the reef flat and not dredging material from deeper water. The lack of difference between the two sample lots would seem to indicate that foraminifera have little to offer in determining the history of cyclonic activity in the region. More detailed analysis of the assemblage however, is more likely to yield measurable differences. Concentrating on the minor constituents of the fauna, in particular the smaller benthic forms, as well as the size range and taphonomic character of the material, suggests differences that can be used to identify cyclonic activity in the sub-recent and geological past.

Strotz, L. C.; Mamo, B. L.

2009-12-01

355

Observations of tropical cyclone structure from WindSat  

Microsoft Academic Search

Passive microwave (PMW) radiometric observations of clouds from multichannel imaging sensors onboard low Earth-orbiting environmental satellites are now a vital operational dataset. The first operational passive microwave sensor was the Special Sensor Microwave\\/Imager onboard the Defense Meteorological Satellite Program satellites, which has been gathering hydrological data records since 1987, and continued with the Tropical Rainfall Measuring Mission (TRMM) and the

F. Joseph Turk; Sabatino DiMichele; Jeff Hawkins

2006-01-01

356

Budget of Angular Momentum and Energy in Tropical Cyclones  

Microsoft Academic Search

The surface stress in tropical storms is computed as a function of the radius, from mean wind data in the troposphere. If only the symmetrical part of the circulation is considered, the stress ranges from 1 dyne per square centimeter in the outskirts to 20 dy\\/cm2 at a distance of 1 degree latitude from the center. Inclusion of the mean

E. Palmn; Herbert Riehl

1957-01-01

357

A Gcm Study of the Impact of Greenhouse Gas Increase on the Frequency of Occurrence of Tropical Cyclones  

Microsoft Academic Search

In order to make inferences on the possible future changes of tropical cyclogenesis frequency, we apply the diagnostic computation of the Yearly Genesis Parameter (YGP) proposed by Gray (1975) to the large-scale fields simulated by a GCM. The YGP is an empirical diagnostic of the frequency of Tropical Cyclones (TCs) based on six physical parameters computed from seasonal means of

J.-F. Royer; F. Chauvin; B. Timbal; P. Araspin; D. Grimal

1998-01-01

358

Identifying Recharge from Tropical Cyclonic Storms, Baja California Sur, Mexico.  

PubMed

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

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

2014-03-17

359

Impact of Parameterized Warm-Rain Microphysical Processes on Simulated Tropical Cyclone Development  

NASA Astrophysics Data System (ADS)

This is a presentation of a study in which the Weather Research and Forecasting (WRF) model was used to investigate the impact of parameterized warm-rain processes in three bulk microphysics parameterization (MP) schemes on the model-simulated tropical cyclone development. The three MP schemes investigated are the Ferrier single-moment 3-category, the WRF single-moment 6-category (WSM6) and the Thompson double-moment 6-category schemes. By diagnosing the source and sink terms of the hydrometeor budget equations, we found that the differences in the warm-rain production rate, particularly by conversion of cloud water to rain water, contribute significantly to the variations in the frozen hydrometeor production and in the overall latent heat release above the freezing level. These differences in parameterized warm-rain production reflect the basic differences of the schemes in the definition of rain droplet size distribution and consequently in spectrum-dependent microphysical processes such as accretion growth of frozen hydrometeors and their sedimentation. Hydrometeor budget analysis of the three schemes indicates that the assumed pathways to the production of frozen hydrometeors are quite sensitive to the amount of available super-cooled rain water and, thus, the uncertainties in the parameterized warm-rain processes can affect the intensification and structure of the model-simulated tropical cyclone. Results from this study strongly suggest that the differences in the single- and double-moment formulations of the three schemes are not the primary factor causing the schemes to behave differently in the tropical environment. More importantly, model users should be aware of the impact of the assumed hydrometeor size distributions on results when choosing any MP scheme for tropical cyclone simulations.

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

2014-05-01

360

Anatomy of sand beach ridges: Evidence from severe Tropical Cyclone Yasi and its predecessors, northeast Queensland, Australia  

NASA Astrophysics Data System (ADS)

Four well-identified tropical cyclones over the past century have been responsible for depositing distinct units of predominantly quartzose sand and gravel to form the most seaward beach ridge at several locations along the wet tropical coast of northeast Queensland, Australia. These units deposited by tropical cyclones display a key sedimentary signature characterized by a sharp basal erosional contact, a coarser grain size than the underlying facies and a coarse-skewed trend toward the base. Coarse-skewed distributions with minimal change in mean grain size also characterize the upper levels of the high-energy deposited units at locations within the zone of maximum onshore winds during the tropical cyclone. These same coarse skew distributions are not apparent in sediments deposited at locations where predominantly offshore winds occurred during the cyclone, which in the case of northeast Australia is north of the eye-crossing location. These sedimentary signatures, along with the geochemical indicators and the degraded nature of the microfossil assemblages, have proven to be useful proxies to identify storm-deposited units within the study site and can also provide useful proxies in older beach ridges where advanced pedogenesis has obscured visual stratigraphic markers. As a consequence, more detailed long-term histories of storms and tropical cyclones can now be developed.

Nott, Jonathan; Chague-Goff, Catherine; Goff, James; Sloss, Craig; Riggs, Naomi

2013-09-01

361

Mesoscale Aspects of the Downshear Reformation of a Tropical Cyclone  

NASA Technical Reports Server (NTRS)

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

2004-01-01

362

Extratropical Transition of Western North Pacific Tropical Cyclones: An Overview and Conceptual Model of the Transformation Stage  

Microsoft Academic Search

Extratropical transition (ET) in the western North Pacific is defined here in terms of two stages:transformation, in which the tropical cyclone evolves into a baroclinic storm; and reintensification,where the transformed storm then deepens as an extratropical cyclone. In this study, 30 ET cases occurring during 1 June-31 October 1994- 98 are reviewed using Navy Operational Global Atmospheric Prediction System analyses;

Peter M. Klein; Patrick A. Harr; Russell L. Elsberry

2000-01-01

363

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

364

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

365

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

366

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

367

Influence of ENSO on formation of tropical cloud clusters and their development into tropical cyclones in the western North Pacific  

NASA Astrophysics Data System (ADS)

study analyzes the influence of El Nio-Southern Oscillation (ENSO) on the activity of tropical cloud clusters (TCCs) in the western North Pacific (WNP). A TCC must have at least one embedded mesoscale convective system and it must persist for more than 24 hours. In all, 2,248 TCCs were identified during July-October 1981-2009. While more (less) TCCs form in the eastern (western) part of the WNP during El Nio years than during normal years, the converse is true during La Nia years. The ratio of tropical cyclone (TC) numbers to TCC numbers (genesis productivity) was 27.3%, higher than found in previous study. TC genesis productivity does not correlate with the Oceanic Nio Index even in subregions of the WNP. The influence of ENSO on TC numbers in each subregion of the WNP was mainly due to changes in TCC number, not changes in TC genesis productivity.

Teng, Hsu-Feng; Lee, Cheng-Shang; Hsu, Huang-Hsiung

2014-12-01

368

Knapp, K. R., and J. P. Kossin (2007), New global tropical cyclone data set from ISCCP B1 geostationary satellite data, Journal of Applied Remote Sensing, 1, 013505  

E-print Network

Knapp, K. R., and J. P. Kossin (2007), New global tropical cyclone data set from ISCCP B1 of the paper are prohibited. #12;Knapp, K. R., and J. P. Kossin (2007), New global tropical cyclone data set. Such reanalyses rely on satellite data, but until now, no comprehensive global satellite data set has been

Kossin, James P.

369

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

370

P h y s i c a l O c e a n o g r a p h y D i v i s i o n Tropical Cyclone Heat Potential  

E-print Network

P h y s i c a l O c e a n o g r a p h y D i v i s i o n Tropical Cyclone Heat Potential Gustavo Goni, Joaquin Trinanes, and Francis Bringas Sudden tropical cyclone (TC) intensification has been ocean eddies, provided that atmospheric conditions are also favorable. Tropical cyclones occur in seven

371

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

372

Polar Satellite Products for the Operational Forecaster: Microwave Analysis of Tropical Cyclones  

NSDL National Science Digital Library

This module introduces forecasters to the use of microwave image products for observing and analyzing tropical cyclones. Microwave data from polar-orbiting satellites is crucial to todays operational forecasters, and particularly for those with maritime forecasting responsibilities where in situ observations are sparse. This module includes information on storm structure and techniques for improved storm positioning using the 37 and 85-91 GHz channels from several satellite sensors. Information on current sensors and on the product availability in the NPOESS era is also presented.

2014-09-14

373

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

374

Predicting tropical cyclone intensity using satellite measured equivalent blackbody temperatures of cloud tops. [regression analysis  

NASA Technical Reports Server (NTRS)

A regression technique was developed to forecast 24 hour changes of the maximum winds for weak (maximum winds less than or equal to 65 Kt) and strong (maximum winds greater than 65 Kt) tropical cyclones by utilizing satellite measured equivalent blackbody temperatures around the storm alone and together with the changes in maximum winds during the preceding 24 hours and the current maximum winds. Independent testing of these regression equations shows that the mean errors made by the equations are lower than the errors in forecasts made by the peristence techniques.

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

1978-01-01

375

Winds, Water Budgets and Stable Isotopes in Tropical Cyclones using TRMM and QUICKSCAT  

NASA Technical Reports Server (NTRS)

Water vapor is the most abundant greenhouse gas in the atmosphere. Changes in its concentration and distribution are controlled by the hydrologic cycle. Because of its capacity to absorb and emit long wave radiation, release latent heat during condensation in storms and reflect short wave radiation when clouds form it has a major impact on Global climate change. The stable isotope ratios of water are H20 H2l6O and H0 H2l6O. These ratios change whenever water undergoes a phase change. They also change in both rain and water vapor whenever an air parcel is exposed to rain. In addition the relative changes in the two ratios differ as a &nction of the relative humidity. In short, the stable isotope ratios in water vapor in the atmosphere contain an integrated history of the processes affecting the concentration and distribution of water vapor in the atmosphere. Therefore the measurement and interpretation of changes in these stable isotope ratios are a powerful tool matched by no other method in tracing the transport history of water in the atmosphere. Our initial studies under this grant focused on the changes of the stable isotope ratios of precipitation and water vapor in tropical cyclones. The changes in time and space were found to be very large and to trace the transport of water in the storms reflecting changes in basic structural features. Because the stable isotope ratios of rains from tropical cyclones are so low flooding associated with land falling tropical cyclones introduces a negative isotopic spike into the coastal surface waters. In addition the stable isotope ratios of water vapor in the vicinity of tropical cyclones is anomalously low. This suggests that carbonate shelled organisms such as ostracoda living in coastal waters have the potential to record the isotopic spike and thereby provide a long term record of tropical storm activity in sediment cores containing fossil shells. Likewise, tree rings in coastal environments offer a similar potential. We have analyzed the oxygen isotopic composition of ostrcoda shells formed in the floodwaters of Tropical Storm Allison (2001) and discovered the negative isotopic 1 16 spike. Because we had learned that storm activity has a major impact on the stable isotope ratios of water vapor in the tropics and sub-tropics we decided to analyze the isotopic compositions of water vapor in different locations in the tropics. We did this in Puerto Escondido, Mexico in July 1998, near Kwajalein Island in the Pacific in 1999 as part of a TRMM summer field program and in 2001 in Key West, Florida as part of the CAMEX 4 summer field program. Our isotopic studies along with our earlier tropical cyclone studies showed that the low isotopic ratios in water vapor induced by exposure to rains the storms persisted for 48 hours often far away from the original storm site. We also noted that positive isotopic spikes were introduced into atmospheric water vapor if winds were high and extensive sea spray was present. These findings have a significant impact on the interpretation of the stable isotope studies of tropical ice cores found in the high mountain regions of the tropics. The assumption made in interpreting the ice core record is that the source water vapor evaporated from the sea surface is in near isotopic equilibrium with the seawater and undergoes a decrease during its transport that reflects the change in temperature from the sea surface to the site of the ice core. Because an additional isotopic depletion occurs at the sea surface source area that depends on the intensity, duration and size of the tropical rain system the isotopic variations found in the ice cores must take into account changes in past storm activity in the tropics. These systems must be an important source of water vapor to the ice cores because they charge the troposphere with water vapor to a far greater vertical height than evaporation in quiescent regions. Finally, an interest in increased heat transfer in thnterior of tropical cyclones resulting from greater amounts of sea spray is a topic of considerab

Lawrence, James R.

2004-01-01

376

Present and Future Impacts of Tropical Cyclones on Urban Flooding in the Eastern United States  

NASA Astrophysics Data System (ADS)

The climatology of flooding in urbanized watersheds in the eastern United States is largely the result of tropical cyclones and organized thunderstorm systems. Extreme rainfall from tropical storms drives the upper tail of flood risk in watersheds larger than about 25 km2. In this study, we couple a flood hazard assessment framework known as Stochastic Storm Transposition (SST) with a ten-year record of high-resolution (15-minute, 1 km2) radar rainfall fields developed using the Hydro-NEXRAD system to look at the frequency of intense rainfall from tropical storms and organized thunderstorms in Charlotte, North Carolina. Using the physics-based Gridded Surface Subsurface Hydrologic Analysis (GSSHA) modeling system, we have developed a detailed representation of the highly urbanized Little Sugar Creek watershed, including detailed land surface, subsurface, and drainage network properties. We use GSSHA to examine the frequency and intensity of extreme flooding resulting from tropical storms and organized thunderstorms at different spatial scales. In addition, we combine this flood hazard assessment framework with downscaled projections of future hurricane-season rainfall from the Zetac regional climate model to examine how projected changes in flood risk due to tropical storm rainfall may change in Charlotte and along the east coast of the United States throughout the 21st century. We demonstrate that the frequency of landfalling tropical storms in the eastern United States is not projected to change significantly from present conditions, but that the intensity of rainfall from these storms will increase by the late 21st century, with important implications for flooding in urban areas. Significant challenges remain, however, with the simulation of rainfall from landfalling tropical storms in climate models. Annual frequency of modeled tropical storm tracks passing within 500 km of a given point during the control period (1980-2006) and the CMIP5 late 21st century climate scenario.

Wright, D. B.; Smith, J. A.; Knutson, T. R.; Baeck, M. L.

2013-12-01

377

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

378

Influence of physics parameterization schemes on the simulation of a tropical-like cyclone in the Mediterranean Sea  

NASA Astrophysics Data System (ADS)

Numerical experiments are performed using the WRF model to investigate which category of model physics is most critical for a proper simulation of the structure and intensity of a Mediterranean hurricane. Several combinations are used, and the model outputs are compared with the available observations and a reference simulation. The choice of microphysics scheme, and in a minor way, of cumulus parameterization, has the greatest impact on the model results. Boundary layer schemes and land-surface models appear to play only a marginal role. The ability of the model to reproduce the evolution of the cyclone from extra-tropical to tropical-like (TLC) is also explored. Apart from a few experiments differing for the microphysical scheme, all simulations are able to reproduce the cyclone features properly, and identify the presence of tropical characteristics, i.e. a symmetric, deep warm core, in the later stage of the cyclone lifetime, but with duration and intensity depending on the experiment. The motivation for the failure in some simulations is traced back to the incorrect representation of the cyclone location along its transit in the southern Ionian Sea, before its transition to TLC. In this phase, the interaction of the intense easterly flow, developing on the northern side of the cyclone, with the Apennines near the coasts of Calabria is fundamental for the later intensification of the cyclone, due to the severe convection triggered by the orographic uplift. Thus, an even small misplacement of the simulated cyclone during this phase may dramatically affect its following evolution. For the sake of comparison with the multi-physics approach, a time-lagged ensemble, with initial conditions starting at different times, is also considered. The spread in the cyclone depth and track in the latter case is smaller or comparable with that emerging in experiments using different microphysical schemes, but is larger compared with the experiments changing the other categories of parameterization schemes.

Miglietta, Mario Marcello; Mastrangelo, Daniele; Conte, Dario

2015-02-01

379

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

380

Integrated impact of tropical cyclones on sea surface chlorophyll in the North Atlantic  

USGS Publications Warehouse

Past studies have shown that surface chlorophyll-a concentrations increase in the wake of hurricanes. Given the reported increase in the intensity of North Atlantic hurricanes in recent years, increasing chlorophyll-a concentrations, perhaps an indication of increasing biological productivity, would be an expected consequence. However, in order to understand the impact of variable hurricane activity on ocean biology, the magnitude of the hurricane-induced chlorophyll increase relative to other events that stir or mix the upper ocean must be assessed. This study investigates the upper ocean biological response to tropical cyclones in the North Atlantic from 1997-2005. Specifically, we quantitatively compare the anomalous chlorophyll-a concentrations created by cyclone activity to the total distribution of anomalies in the subtropical waters. We show that the cyclone-induced chlorophyll-a increase has minimal impact on the integrated biomass budget, a result that holds even when taking into consideration the lagged and asymmetrical response of ocean color. Copyright 2008 by the American Geophysical Union.

Hanshaw, M.N.; Lozier, M.S.; Palter, J.B.

2008-01-01

381

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

382

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.

383

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

384

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

NASA Technical Reports Server (NTRS)

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

Spencer, Roy W.; Braswell, William D.

2001-01-01

385

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

386

ESTIMATING THE BENEFIT OF TRMM TROPICAL CYCLONE DATA IN SAVING LIVES  

NASA Technical Reports Server (NTRS)

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

Adler, Robert F.

2005-01-01

387

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

388

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, Rene.; Gledhill, Dwight

2013-10-01

389

The Impact of Tropical Cyclones on Coral Bleaching and Coral Diseases  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TCs) impact coral reef ecology in various ways, they cool down ambient sea surface temperature (SST), damage coral reefs by wave action, decrease salinity, increase nutrients, and increase sedimentation rates on a reef. Here we present an investigation into the effect of TCs on coral bleaching and the effect TCs have on the occurrence of coral diseases. Coral bleaching, the condition where the symbiotic zooxanthellae leave the coral host, is one of the major threats to coral reefs. Bleaching occurs in anomalously warm waters, analysis of historical TC tracks show that TCs frequently occur near coral bleaching episodes. Intriguingly, TCs cool down sea surface temperature by vertical mixing and as SST is the most important factor in coral bleaching this phenomenon might have an impact on the duration, occurrence and the resulting coral mortality, of bleaching events. In recent literature a correlation has been seen in the power of tropical cyclones and average sea surface temperature, making the study of the effect of TCs on the ecology of reefs an urgent one. We will present case studies where a TCs occurred near bleaching episodes and a statistical analysis to quantify this effect. To do this we use historical cyclone track data, satellite SST data, and a dataset of reefs. But there are other TC effects on reefs that bear investigation. Because TCs occur near corals that experience thermal stress, the changes in the corals environment caused by TCs might be anomalously detrimental. For example, data suggests that corals, because they are stressed by increased sedimentation, are more vulnerable to disease and algal overgrowth after TC damage. Nutrients have been shown to increase the severity of coral diseases. With satellite data it can be shown that short-term events such as increased run-off due to tropical cyclones can be an important part of the distribution of pollutants and pathogens affecting reefs. Infectious diseases severely affect scleractinian corals. We compare a database of coral disease outbreaks and a database of historical hurricane tracks and quantify run-off using satellite data to investigate the hypothesis that TCs can contribute to the spread of coral diseases by run-off induced transport of sediment, nutrients, pollutants and pathogens to a reef.

van Hooidonk, R. J.; Huber, M.

2006-12-01

390

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

391

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

392

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

393

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

394

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

395

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.; Stssel, Marion M.; Zhang, Xiaoqian; Howard, Matthew K.; du Vall, Ken

2012-06-01

396

Large-Scale Influences on the Genesis of Tropical Cyclone Karl (2010)  

NASA Astrophysics Data System (ADS)

The events leading up to the genesis of Tropical Cyclone (TC) Karl (2010) provides a unique opportunity to examine the continuing problem of understanding tropical cyclogenesis. The PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) field campaign allowed for detailed investigation of the tropical disturbance that served as the precursor to TC Karl as it progressed westward through the Caribbean Sea. The purpose of this presentation is to examine the evolution of the pre-Karl disturbance using both common synoptic-scale analyses as well as statistically-based equatorial wave analyses, focusing on where these analyses complement and enhance each other. One of the major factors in the initial spin-up of the pre-Karl tropical disturbance is a surge of southerly and westerly winds from northern South America on 8-10 September 2010. As the surge entered the Caribbean on 9 September, it aided in the formation of a nearly closed earth-relative cyclonic circulation near the southern Leeward Islands. This circulation weakened late on 10 September and remained weak through 13 September before increased organization led to TC genesis on 14 September. This southerly wind surge can be traced to a well-defined surge of anomalously cold air and enhanced southerly winds originating in the lee of the Argentinian Andes over a week prior. While the temperature anomalies wash out prior to reaching the equator, anomalous low-level winds progress into Colombia and Venezuela, where topography aids in turning the southerly winds eastward. An investigation of the pre-Karl environment utilizing wavenumber-frequency filtering techniques also suggests that the initial spin-up of pre-Karl can be associated with the active phase of a convectively coupled Kelvin wave (CCKW). The observed formation of the nearly closed cyclonic circulation on 10 September is well timed with the passage of anomalous westerly winds along and behind the convectively active phase of a CCKW. These westerly wind anomalies have been associated with an increase in the frequency of TC genesis, commonly attributed to the generation of low-level cyclonic vorticity and a reduction in climatological shear over the western Atlantic by other researchers. Further, the total wind field associated with a CCKW promotes deep convection via the enhancement of low-level convergence and upper-level outflow ahead of the wave. The passage of the CCKW during 8-10 September occurs in concert with the aforementioned cold surge-related enhanced low-level southerly winds that turn eastward as they cross the equator, further strengthening the westerly wind anomalies associated with the CCKW. This favorable juxtaposition of low-level southerly and westerly flows results in the amplification of convective activity associated with the CCKW around the time the CCKW interacts with the pre-Karl disturbance and likely serves to enhance the resulting low-level cyclonic circulation, eventually leading to the genesis of TC Karl.

Griffin, K.; Bosart, L. F.

2012-12-01

397

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

398

Saharan dust, lightning and tropical cyclones in the eastern tropical Atlantic during NAMMA-06  

Microsoft Academic Search

During the summer of 2006, the downstream component of African Monsoon Multidisciplinary Analyses Campaign (NASA-AMMA (NAMMA)) examined African Easterly Waves (AEWs) emerging from the coast of Africa. Six of these disturbances went on to become named systems in the Tropical Atlantic. Two of the six systems (Tropical storm Debby and Hurricane Helene) developed in the extreme eastern Atlantic and were

Gregory S. Jenkins; Aaron Pratt

2008-01-01

399

Reexamining the Near-Core Radial Structure of the Tropical Cyclone Primary Circulation: Implications for Vortex Resiliency  

Microsoft Academic Search

Recent theoretical studies, based on vortex Rossby wave (VRW) dynamics, have established the impor- tance of the radial structure of the primary circulation in the response of tropical cyclone (TC)-like vortices to ambient vertical wind shear. Linear VRW theory suggests, in particular, that the degree of broadness of the primary circulation in the near-core region beyond the radius of maximum

Kevin J. Mallen; Michael T. Montgomery; Bin Wang

2005-01-01

400

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

NASA Astrophysics Data System (ADS)

The impact of El Nio 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 Nio years the number of tropical cyclones landfalling in the landmasses rimming the western North Pacific is significantly reduced. The exception is Japan and the Korean Peninsula. On the other hand, in the late season of La Nia years, China can expect significantly more landfalls. The predictability of the number of landfalling tropical cyclones in the western North Pacific is found to be the highest for China in the late season of La Nia years.The reduction in the number of landfalls during the late season of El Nio years seems to be related to an eastward shift in the mean tropical cyclone genesis position and a break in the 500-hPa subtropical ridge near 130E. In contrast, the increase in the number of landfalls during the late season of La Nia years appears to be related to a westward shift in the mean genesis position together with a contiguous 500-hPa subtropical ridge.

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

2004-03-01

401

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

402

Analysis of Water Properties and Geostrophic Currents in FijiWaters Before and After Tropical Cyclone Gene  

Microsoft Academic Search

Problem statement: Water properties influence ocean primary productio n and drive the ocean food chain. This study depicts changes in tem perature and salinity and its effects on geostrophi c currents near Fiji before and after Tropical Cyclon e (TC) Gene. Approach: Available Argo float data from 6 January-4 February 2008 were used for analysis since TC Gene passed the

Shivneel Prasad; Than Aung; Awnesh Singh

2009-01-01

403

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

404

On the Decay of Tropical Cyclone Winds after Landfall in the New England Area.  

NASA Astrophysics Data System (ADS)

A version of the Kaplan and DeMaria empirical model for predicting the decay of tropical cyclone 1-min maximum sustained surface winds after landfall is developed for the New England region. The original model was developed from the National Hurricane Center (NHC) best-track wind estimates for storms that made landfall in the United States south of 37N from 1967 to 1993. In this note, a similar model is developed for U.S. storms north of 37N, which primarily made landfall in New York or Rhode Island and then moved across New England. Because of the less frequent occurrence of New England tropical cyclones, it was necessary to include cases back to 1938 to obtain a reasonable sample size. In addition, because of the faster translational speed and the fairly rapid extratropical transition of the higher-latitude cases, it was necessary to estimate the wind speeds at 2-h intervals after landfall, rather than every 6 h, as in the NHC best track. For the model development, the estimates of the maximum sustained surface winds of nine landfalling storms (seven hurricanes and two tropical storms) at 2-h intervals were determined by an analysis of all available surface data. The wind observations were adjusted to account for variations in anemometer heights, averaging times, and exposures.Results show that the winds in the northern model decayed more (less) rapidly than those of the southern model, when the winds just after landfall are greater (less) than 33 knots. It is hypothesized that this faster rate of decay is due to the higher terrain near the coast for the northern sample and to the more hostile environmental conditions (e.g., higher vertical wind shear). The slower decay rate when the winds fall below 33 knots in the northern model might be due to the availability of a baroclinic energy source as the storms undergo extratropical transition.

Kaplan, John; Demaria, Mark

2001-02-01

405

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 Nio 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; Bruyre, Cindy L.

2014-06-01

406

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

407

Tropical cyclone intensity estimation using temporal and image analysis of satellite data  

NASA Astrophysics Data System (ADS)

Tropical cyclones (TCs) are becoming an increasing threat to life and property. Developing an automated technique to estimate TC intensity and to overcome the existing errors in estimation is still a challenge. The Dvorak technique (DT) is the state-of-the-art method that has been used over three decades for estimating the intensity of a tropical cyclone. The DT subjectively estimates TC intensity based on visible and infrared satellite images. In spite of wide usage of the DT for TC analysis, it has some limitations. The most important one is that the DT does not use the valuable historical data mainly because of the challenges on computing and human resources. This research is inspired by the availability of historical TC satellite data. We hypothesize that discovering unknown regularities and abnormalities that may exist in the large group of past observations could help human experts interpret TC intensity changes from various points of view. Our goal is to provide a data mining tool that increases the ability of human experts to analyze huge amount of historical data for TC intensity estimation. The proposed intensity estimation algorithm has two parts: temporal constraints and image analysis. Temporal information provides a priori estimates of storm intensity (in terms of wind speed) prior to using any satellite image analysis. Hurricane Satellite data (HURSAT-B1) includes best-track intensity are used as a training data. A case study using North Atlantic Hurricane Satellite data from 1988-2009 is considered. The temporal analysis uses the age of the cyclone, 6, 12 and 24 hours prior intensities as predictors of the expected intensity. The 10 closest analogs (determined by a K-nearest-neighbor algorithm) are averaged to estimate the intensity. The distribution of intensity estimation errors of the proposed technique shows that 50% of the estimates have a mean absolute error less than 4.4 knots, 75% are 6.3 knots and 90% are within 8 knots. Several validation tests were conducted to statistically justify the proposed algorithm using K-Fold Cross-Validation. The resulting average root mean squared error (RMSE) of our algorithm is approximately 4.6 knots. Overall, 47% improvement has been achieved compared to the DT. The current analysis has the ability to decrease the DT noise and has the potential to provide new temporal constraints on DT. The image analysis part of the proposed technique used the average and standard deviation of the brightness temperature of the selected rings around the center of the storm, as predictors of the current intensity of the storm. The image analysis used the age of the cyclone, current, 6, 12 and 24 hours prior images as predictors of the expected intensity as well. As like as temporal analysis, the intensity of the 10 closest analogs (determined by a K-nearest-neighbor algorithm) in training data are averaged to estimate the intensity. The result of K-Fold Cross-Validation shows that the accuracy of the proposed technique on likely par with current objective techniques. Simplicity aspect of the image analysis part of the planned technique makes it superior to other techniques. Research is continued to combine the image and temporal analysis part of suggested technique to achieve more accuracy in tropical cyclone intensity estimation.

Fetanat, G.; Homaifar, A.; Knapp, K.

2012-12-01

408

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 Universit 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

409

Q. J. R. Meteorol. Soc. (2003), 129, pp. 14691490 doi: 10.1256/qj.01.91 Numerical diagnosis of a small, quasi-tropical cyclone over the western  

E-print Network

of a small, quasi-tropical cyclone over the western Mediterranean: Dynamical vs. boundary factors By V. HOMAR; revised 19 April 2002) SUMMARY A small, quasi-tropical cyclone occurred on 12 September 1996 over. Mesoscale model runs properly simulate the cyclone formation and show convection and heavy precipitation

Romero, Romu

410

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

411

AMSU-A Tropical Cyclone Maximum Sustained Winds and Web Site  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

412

Saharan dust, lightning and tropical cyclones in the eastern tropical Atlantic during NAMMA-06  

NASA Astrophysics Data System (ADS)

During the summer of 2006, the downstream component of African Monsoon Multidisciplinary Analyses Campaign (NASA-AMMA (NAMMA)) examined African Easterly Waves (AEWs) emerging from the coast of Africa. Six of these disturbances went on to become named systems in the Tropical Atlantic. Two of the six systems (Tropical storm Debby and Hurricane Helene) developed in the extreme eastern Atlantic and were associated with dust outbreaks, elevated ice contents and frequent lightning. Here we show that in the early tropical cyclo-genesis stages of these systems there were thousands of cloud-to-ground (CG) lightning flashes as measured by a ground-lightning network. TRMM overpasses show high precipitation ice content above the freezing level and high latent heat release. Super-cooled water can be inferred in the lower parts of cloud systems in concert with observed high ice concentrations at high altitudes creating charge separation based on the large numbers of CG flashes.

Jenkins, Gregory S.; Pratt, Aaron

2008-06-01

413

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

414

Increase in the Intensity of Postmonsoon Bay of Bengal Tropical Cyclones  

SciTech Connect

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

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

2014-05-28

415

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

416

Interdecadal variability of tropical cyclone landfall in the Philippines from 1902 to 2005  

NASA Astrophysics Data System (ADS)

A dataset of tropical cyclone landfall numbers in the Philippines (TLP) is created from a combination of historical observation records of the Monthly Bulletins of Philippine Weather Bureau and Joint Warning Typhoon Center best-track data for the period of 1902 to 2005. Interdecadal variability of TLP is found to be related to different phases of the El Nio/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). The annual TLP has an apparent oscillation of about 32 years before 1939 and an oscillation of about 10-22 years after 1945. No long-term trend is found. During the low PDO phase, the annual TLP decreases (increases) significantly in El Nio (La Nia) years. During high PDO phase, however, the difference in annual TLP between different ENSO phases becomes unclear. These results suggest that natural variability related to ENSO and PDO phases appears to prevail in the interdecadal variability of TLP.

Kubota, Hisayuki; Chan, Johnny C. L.

2009-06-01

417

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.

2011-07-01

418

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

419

Generated using version 3.2 of the official AMS LATEX template Dynamical and physical processes leading to tropical cyclone1  

E-print Network

leading to tropical cyclone1 intensification under upper-level trough forcing2 Marie-Dominique Leroux M´et´eo-France, Laboratoire de l'Atmosph`ere et des Cyclones, Unit´e mixte 8105 CNRS/M´et´eo-France/ Universit´e de La R des Cyclones, Unit´e mixte 8105 CNRS/M´et´eo-France/ Universit´e de La R´eunion, Sainte Clotilde

420

Dynamical downscaling of Tropical Cyclone activity from NCEP/NCAR and ERA 40 reanalysis data sets.  

NASA Astrophysics Data System (ADS)

In order to derive climate statistics, long and homogeneous time series are needed. Observational data sets (best track data) of tropical cyclone activity in the western North Pacic basin show strong discrepancies in the long-term trends derived for the last decades. We derive alternative datasets of tropical cyclone (TC) activity, by applying dynamical downscaling approach. Two reanalysis data sets: NCEP/NCAR 1 and ERA 40 are downscaled, using an atmospheric regional model (CCLM). The reconstructed TC variability (yearly and climate-scale) yields good agreement with the observed one, mainly for the last three decades. Reconstructed and observed long-term trends (1948-2011) of TC frequency differ. Both reanalyses reveal a strong increase of TC activity, while observation-based data sets show rather decadal variability. Additional analysis indicates that the reconstructed long - term (1948-2011) TC activity may suffer from temporal inhomogeneities included in both sets of reanalyses, which were used to drive the regional climate model. For both simulations TC intensity reveals abrupt upward shift in 1978, which coincides with the introduction of satellite-based observations to reanalyses. Moreover, differences between the regional climate model simulations forced by either NCEP/NCAR 1 or ERA 40 point also to uncertainties associated with intrinsic features and quality changes of the reanalyses (e.g. observational data and methods of data assimilation). Therefore the interpretation of dynamically downscaled reanalyses should be treated with caution, especially for the pre-satellite period. Study discuss the reliability of the results, derived from downscaling the inhomogeneous data set.

Barcikowska, Monika; Feser, Frauke; von Storch, Hans

2014-05-01

421

The Moistening and Drying Effect of Tropical Cyclones in Mexico Climate  

NASA Astrophysics Data System (ADS)

Tropical Cyclones (TCs) are supplying mechanisms of water to the country and allow recharging aquifers, rivers, lakes and stratus of groundwater. TCs play a more important role in the hydrological cycle of northern Mexico and they are such an essential elements during summer rainfall seasons in Mexico that if they did not exist, summer rainfall would decrease its amount by half in numerous Mexican regions. For instance, there could be a high TC activity both Atlantic and Pacific Ocean, a rainfall season could not be enough to become important if TCs do not pass over Mexico. We examine the two opposite effects of Tropical Cyclones (TCs) on Mexico, during the period 1979-2009, by means of a probabilistic clustering technique. One TC effect is their contribution to summer rainfall, which is defined as "the moistening effect". The other effect is to dry regions due to subsidence induced by their circulation, which is defined as "the drying effect". The TCs tracks for the North Atlantic and Eastern North Pacific Oceans are obtained from the best-track database of National Hurricane Centre (HURDAT and EPA). Four principal types of tracks (clusters) in both basins are defined and each cluster has a different impact on Mexico. Consequently, this shows how important defining clusters are to analyze TC effects. We conclude that, climatologically, TCs may contribute up to 30% of summer rainfall depending on the cluster. In addition, the subsidence effect is not large, compared to the generated amount of precipitation in a region, but acts to produce negative precipitation anomalies over Mexican regions that depend on their distance of the system to Mexico.

Domnguez Sarmiento, C.; Magaa Rueda, V.

2013-05-01

422

Simulation of wind performance in tropical cyclone for China's future dual-frequency wind field radar  

NASA Astrophysics Data System (ADS)

Ocean surface wind vectors (OVW) from scatterometers have been proved to be of great benefit to marine weather analysis and numerical model prediction. Conventional single-frequency scatterometers are capable to measure substantially accurate wind fields in clear atmospheric conditions, whereas winds obtained in marine extreme weather conditions are not so satisfying due to the high wind speed saturation effect and the rain perturbation. Therefore, a dualfrequency wind field measuring radar (WIFIR) to be onboard FengYun-3E is being predesigned to obtain relatively accurate wind fields in all weather conditions, which will compensate for the single-frequency shortcomings. The purpose of this study was to investigate the potential ability of WIFIR to measure OVW in tropical cyclones. A high-fidelity forward model was developed to simulate the sea surface normalize radar cross sections (NRCS) measured by WIFIR. The wind and rain rate fields used to drive the model are generated by UWNMS cloud model for Hurricane Ivan in 2004. High-wind GMFs and a theoretical rain model, which includes attenuation and volume scattering effect, have been utilized to describe the forward model. Based on the simulation results, the impact of rain on radar measurements and a dual-frequency retrieval algorithm were studied. The dual-frequency method was shown to have the ability to obtain information of rain rates up to 30mm/hr, and acquire more accurate wind vectors than single-frequency measurements. This method will be more effective to improve wind retrieval accuracy in tropical cyclones with the synchronous observation of microwave humidity sounder (MWHS) aboard FY-3 satellite.

Dou, Fangli; Yin, Honggang; Gu, Songyan

2014-11-01

423

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. Garca-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. Garca-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).

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

2009-04-01

424

Investigation of predictability during the Extratropical Transition of Tropical Cyclones using the THORPEX Interactive Grand Global Ensemble (TIGGE)  

NASA Astrophysics Data System (ADS)

Several times per year tropical cyclones pass through a recurvature after their typical tropical life-cycle. They start to interact with the mid-latitude flow and may be transformed into an extratropical system. Such an extratropical transition (ET) process of a tropical cyclone often leads to a reduction in the predictability for the synoptic development of the cyclone itself as well as for the downstream region. Recent studies investigated the predictability during ET events based on the variability among members of single operational medium-range ensemble forecasts. The new THORPEX Interactive Grand Global Ensemble (TIGGE) provides an opportunity to extend these previous studies. TIGGE was established in the world weather research program THORPEX and combines the forecasts of 10 different EPS, operated at weather services all over the world. They are based on different assumptions, initial perturbation methods, resolutions and they also differ in the number of ensemble members, contained in the forecast. Thus TIGGE offers the possibility to compare predictability during ET events in a number of different ensemble prediction systems (EPS). Furthermore, TIGGE may show new possible development scenarios that could not be gained, using one single EPS. To extract the information, contained in the ensemble forecasts, we perform an empirical orthogonal function (EOF) analysis on the variance-covariance-matrix of the forecast field in question. By calculating the principal components we get information, how each member, contained in the ensemble forecast contributes to the obtained EOF distribution. Using a fuzzy clustering, all members that show a related contribution, are grouped together. Thus, this analysis process allows us to extract possible development scenarios out of the ensemble forecast and at the same time we gain information about the possibility of these scenarios. For our investigations eight of the ten TIGGE EPS are used and interpolated to the same horizontal resolution and pressure levels. The investigations are mainly done for the geopotential height at a 200 hPa pressure level, to catch the interaction between the mid-latitude jet and the outflow of the tropical cyclone. Using this data base and analysis technique, we perform case studies of several tropical cyclones, which underwent ET in 2008 or later. The focus here is to study the dominant development scenarios, to identify the physical processes that produce the different developments and lead to the reduction of forecast skills during an ET event. To address the question as to how the tropical cyclone influences the development, an analysis of the eddy kinetic energy budget is performed on several interesting scenarios. Furthermore, we investigate the behavior of the several TIGGE EPS and their contribution to the different development scenarios. In this presentation a selected case study will be introduced.

Keller, J. H.; Jones, S. C.; Anwender, D.

2010-09-01

425

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

426

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

NASA Technical Reports Server (NTRS)

Barrier Islands are the first line of defense against tropical storms and hurricanes for coastal areas. Historically, tropical cyclonic events have had a great impact on the transgression of barrier islands, especially the Chandeleur Island chain off the eastern coast of Louisiana. These islands are of great importance, aiding in the protection of southeastern Louisiana from major storms, providing habitat for nesting and migratory bird species, and are part of the second oldest wildlife refuge in the country. In 1998, Hurricane Georges caused severe damage to the chain, prompting restoration and monitoring efforts by both federal and state agencies. Since then, multiple storm events have steadily diminished the integrity of the islands. Hurricane Katrina in 2005 thwarted all previous restoration efforts, with Hurricane Gustav in 2008 exacerbating island erosion and vegetation loss. Data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Moderate Resolution Imaging Spectroradiometer (MODIS), Landsat 2-4 Multispectral Scanner (MSS), and Landsat 5 Thematic Mapper (TM) will be utilized to detect land loss, island transgression, and vegetation change from 1979 to 2009. This study looks to create a more synoptic view of the transgression of the Chandeleur Islands and correlate weather and sea surface phenomena with erosion trends over the past 30 years, so that partnering organizations such as the Pontchartrain Institute for Environmental Sciences (PIES) can better monitor and address the continual change of the island chain.

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

2010-01-01

427

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

428

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

E-print Network

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 are generated and landfall rates computed. Compared to direct analysis of historical landfall, the track model reduces the sampling error by projecting information from the entire basin onto the coast. There are 46% more TCs in hot years than cold in the model, which is highly significant compared to random sampling and corroborates well documented trends in North Atlantic TC number in recent decades. In the absence of other effects, this difference results in a significant increase in model landfall rates in hot years, uniform along the coast. Hot-cold differences in the geographic distribution of genesis and in TC propagation do not...

Hall, Timothy

2008-01-01

429

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

430

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

431

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

432

Climatic Determinants and Statistical Prediction of Tropical Cyclone Days in the Southwest Indian Ocean.  

NASA Astrophysics Data System (ADS)

Climatic determinants of tropical cyclone (TC) days in the southwest Indian Ocean area (10-25S, 50-70E) are analyzed using statistical techniques. A TC days index is formulated from records of local meteorological services over the December-March season in the period 1961-91. The index is correlated with gridded fields of sea surface temperature (SST), outgoing longwave radiation (OLR), and tropospheric winds, using monthly standardized departures at various lags.SST relationships with TC days are positive over the entire southwest Indian Ocean from 4 to +2 months, as expected. Peak correlations of >+0.5 occur in the genesis region 0-10S, 50-60E to the northeast of Madagascar at lag 4 (September). The synoptic-scale response of monsoon convection is approximated by OLR correlations. Negative correlations (associated with increased convection) are found to the northeast of Madagascar at lag 4 and 0 months. At lags 4 and 2 (November) opposing positive OLR correlations are found over Africa, suggesting a convective sink region during the spring season transition.Wind correlation vectors at the 200-hPa level indicate the persistence of an anticyclonic gyre centered near 35S, 70E in the south Indian Ocean and upper easterly flow in the equatorial zone. Surface northwesterly flow is a prominent feature in the central Indian Ocean (Diego Garcia), while strengthened midlatitude westerlies are found at lag 4 (September). In November surface northwesterly flow anomalies dominate the entire tropical zone with respect to summers with increased TC days. At lag 0 and to a lesser extent +2 months, a distinct cyclonic anomaly is centered on 20S, 55E with enhanced monsoon westerlies to the north.The correlation patterns offer statistical guidance in long-range forecasts and insights to the climatic processes involved in the interannual variability of TC days in the southwest Indian Ocean. Using predictors selected from present analysis, a linear multivariate model is constructed. The model has three predictors from the preceding July to November period and accounts for 59% of the variance over the 1971-92 period. The model performs adequately, achieving a jackknife correlation of 70% and a Heidke tercile score of 52.5%. A conceptual framework is used to highlight relationships between the predictors, the Indian monsoon, and tropical cyclogenesis.

Jury, Mark R.; Pathack, Beenay; Parker, Bhawoodien

1999-06-01

433

An assessment of uncertainties and limitations in simulating tropical cyclone climatology and future changes  

NASA Astrophysics Data System (ADS)

The recent elevated North Atlantic hurricane activity has generated considerable interests in the interaction between tropical cyclones (TCs) and climate change. The possible connection between TCs and the changing climate has been indicated by observational studies based on historical TC records; they indicate emerging trends in TC frequency and intensity in some TC basins, but the detection of trends has been hotly debated due to TC track data issues. Dynamical climate modeling has also been applied to the problem, but brings its own set of limitations owing to limited model resolution and uncertainties. The final goal of this study is to project the future changes of North Atlantic TC behavior with global warming for the next 50 years using the Nested Regional Climate Model (NRCM). Throughout the course of reaching this goal, various uncertainties and limitations in simulating TCs by the NRCM are identified and explored. First we examine the TC tracking algorithm to detect and track simulated TCs from model output. The criteria and thresholds used in the tracking algorithm control the simulated TC climatology, making it difficult to objectively assess the model's ability in simulating TC climatology. Existing tracking algorithms used by previous studies are surveyed and it is found that the criteria and thresholds are very diverse. Sensitivity of varying criteria and thresholds in TC tracking algorithm to simulated TC climatology is very high, especially with the intensity and duration thresholds. It is found that the commonly used criteria may not be strict enough to filter out intense extratropical systems and hybrid systems. We propose that a better distinction between TCs and other low-pressure systems can be achieved by adding the Cyclone Phase technique. Two sets of NRCM simulations are presented in this dissertation: One in the hindcasting mode, and the other with forcing from the Community Climate System Model (CCSM) to project into the future with global warming. Both of these simulations are assessed using the tracking algorithm with cyclone phase technique. The NRCM is run in a hindcasting mode for the global tropics in order to assess its ability to simulate the current observed TC climatology. It is found that the NRCM is capable of capturing the general spatial and temporal distributions of TCs, but tends to overproduce TCs particularly in the Northwest Pacific. The overprediction of TCs is associated with the overall convective tendency in the model added with an outstanding theory of wave energy accumulation leading to TC genesis. On the other hand, TC frequency in the tropical North Atlantic is under predicted due to the lack of moist African Easterly Waves. The importance of high-resolution is shown with the additional simulation with two-way nesting. The NRCM is then forced by the CCSM to project the future changes in North Atlantic TCs. An El Nino-like SST bias in the CCSM induced a high vertical wind shear in tropical North Atlantic, preventing TCs from forming in this region. A simple bias correction method is applied to remove this bias. The model projected an increase both in TC frequency and intensity owing to enhanced TC genesis in the main development region, where the model projects an increased favorability of large-scale environment for TC genesis. However, the model is not capable of explicitly simulating intense (Category 3--5) storms due to the limited model resolution. To extrapolate the prediction to intense storms, we propose a hybrid approach that combines the model results and a statistical modeling using extreme value theory. Specifically, the current observed TC intensity is statistically modeled with the General Pareto distribution, and the simulated intensity changes from the NRCM are applied to the statistical model to project the changes in intense storms. The results suggest that the occurrence of Category 5 storms may be increased by approximately 50% by 2055.

Suzuki-Parker, Asuka

2011-07-01

434

The Relation Between Dry Vortex Merger and Tropical Cyclone Genesis over the Atlantic Ocean  

SciTech Connect

A strong, convective African tropical disturbance has a greater chance to develop into a Tropical 23 Depression (TD) if it merges with a shallow, dry vortex (D-vortex) from the north of the African 24 easterly jet (AEJ) after leaving the western coast. Using 11-year reanalysis data we found that the 25 western tip of a vortex strip at northwestern Africa can serve as dry vortices for the D-vortex 26 me