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Sample records for classifying tropical cyclones

  1. Tropical Cyclones John, Steve

    E-print Network

    Greenslade, Diana

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

  2. Mechanics of Tropical Tropical Cyclones

    E-print Network

    Olszewski Jr., Edward A.

    Ocean · Severe Tropical Cyclone ­ SW Pacific Ocean, SE Indian Ocean · Severe Cyclonic Storm ­ N Indian Ocean · Tropical Cyclone ­ SW Indian Ocean · Hurricane ­ N Atlantic, S and NE Pacific #12;Tropical for development Image of Hurricane Andrew, Courtesy of Greenpeace #12;Tropical Cyclones · Typhoon ­ NW Pacific

  3. Tropical cyclone formation

    SciTech Connect

    Montgomery, M.T.; Farrell, B.F. )

    1993-01-15

    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.

  4. Classifying North Atlantic Tropical Cyclone Tracks by Mass Moments* JENNIFER NAKAMURA

    E-print Network

    Biasutti, Michela

    cyclones lead to major natural disasters in the regions of landfallwithdevastating stormsurges, flooding and Landsea (1998)]. The severity and frequency of NS is consequently of great interest for disaster planning

  5. Assessing Tropical Cyclone Damage

    NASA Astrophysics Data System (ADS)

    Done, J.; Czajkowski, J.

    2012-12-01

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

  6. Tropical Cyclone Gonu

    NASA Technical Reports Server (NTRS)

    2007-01-01

    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.

  7. Atlantic tropical cyclones revisited

    NASA Astrophysics Data System (ADS)

    Mann, Michael E.; Emanuel, Kerry A.; Holland, Greg J.; Webster, Peter J.

    Vigorous discussions have taken place recently in Eos [e.g., Mann and Emanuel, 2006; Landsea, 2007] and elsewhere [Emanuel, 2005; Webster et al., 2005; Hoyos et al., 2006; Trenberth and Shea, 2006; Kossin et al., 2007] regarding trends in North Atlantic tropical cyclone (TC) activity and their potential connection with anthropogenic climate change. In one study, for example [Landsea, 2007], it is argued that a substantial underestimate of Atlantic tropical cyclone counts in earlier decades arising from insufficient observing systems invalidates the conclusion that trends in TC behavior may be connected to climate change. Here we argue that such connections are in fact robust with respect to uncertainties in earlier observations.Several recent studies have investigated trends in various measures of TC activity. Emanuel [2005] showed that a measure of total power dissipation by TCs (the power dissipation index, or PDI) is highly correlated with August-October sea surface temperatures (SST) over the main development region (MDR) for Atlantic TCs over at least the past half century. Some support for this conclusion was provided by Sriver and Ruber [2006]. Webster et al. [2005] demonstrated a statistically significant increase in recent decades in both the total number of the strongest category cyclones (categories 4 and 5) and the proportion of storms reaching hurricane intensity. Hoyos et al. [2006] showed that these increases were closely tied to warming trends in tropical Atlantic SST, while, for example, the modest decrease in vertical wind shear played a more secondary role. Kossin et al. [2007] called into question some trends in other basins, based on a reanalysis of past TC data, but they found the North Atlantic trends to be robust.

  8. Tropical Cyclone Indlala

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On March 14, 2007, storm-weary Madagascar braced for its fourth land-falling tropical cyclone in as many months. Cyclone Indlala was hovering off the island's northeast coast when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this photo-like image at 1:40 p.m. local time (10:40 UTC). Just over a hundred kilometers offshore, the partially cloudy eye at the heart of the storm seems like a vast drain sucking in a disk of swirling clouds. According to reports from the Joint Typhoon Warning Center issued less than three hours after MODIS captured this image, Indlala had winds of 115 knots (132 miles per hour), with gusts up to 140 knots (161 mph). Wave heights were estimated to be 36 feet. At the time of the report, the storm was predicted to intensify through the subsequent 12-hour period, to turn slightly southwest, and to strike eastern Madagascar as a Category 4 storm with sustained winds up to 125 knots (144 mph), and gusts up to 150 knots (173 mph). According to Reuters AlertNet news service, Madagascar's emergency response resources were taxed to their limit in early March 2007 as a result of extensive flooding in the North, drought and food shortages in the South, and three previous hits from cyclones in the preceding few months: Bondo in December 2006, Clovis in January 2007, and Gamede in February.

  9. Midlevel Ventilation's Constraint on Tropical Cyclone Intensity

    E-print Network

    Tang, Brian Hong-An

    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 cyclone’s intensity. An ...

  10. Tropical Cyclone Information System

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  11. Tropical Cyclones and Climate Change

    E-print Network

    Knutson, Thomas R.

    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 ...

  12. Counting Atlantic Tropical Cyclones Back to 1900

    NASA Astrophysics Data System (ADS)

    Landsea, Christopher W.

    2007-05-01

    Climate variability and any resulting change in the characteristics of tropical cyclones (tropical storms, subtropical storms, and hurricanes) have become topics of great interest and research within the past 2 years [International Workshop on Tropical Cyclones, 2006]. An emerging focus is how the frequency of tropical cyclones has changed over time and whether any changes could be linked to anthropogenic global warming.

  13. 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

  14. A Ventilation Index for Tropical Cyclones

    E-print Network

    Tang, Brian

    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 ventilation—or the flux of ...

  15. Estimating tropical cyclone precipitation risk in Texas

    E-print Network

    Zhu, Laiyin

    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 ...

  16. Black Swan Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Emanuel, K.; Lin, N.

    2012-12-01

    Virtually all assessments of tropical cyclone risk are based on historical records, which are limited to a few hundred years at most. Yet stronger TCs may occur in the future and at places that have not been affected historically. Such events lie outside the realm of historically based expectations and may have extreme impacts. Their occurrences are also often made explainable after the fact (e.g., Hurricane Katrina). We nickname such potential future TCs, characterized by rarity, extreme impact, and retrospective predictability, "black swans" (Nassim Nicholas Taleb, 2007). As, by definition, black swan TCs have yet to happen, statistical methods that solely rely on historical track data cannot predict their occurrence. Global climate models lack the capability to predict intense storms, even with a resolution as high as 14 km (Emanuel et al. 2010). Also, most dynamic downscaling methods (e.g., Bender et al. 2010) are still limited in horizontal resolution and are too expensive to implement to generate enough events to include rare ones. In this study, we apply a simpler statistical/deterministic hurricane model (Emanuel et al. 2006) to simulate large numbers of synthetic storms under a given (observed or projected) climate condition. The method has been shown to generate realistic extremes in various basins (Emanuel et al. 2008 and 2010). We also apply a hydrodynamic model (ADCIRC; Luettich et al. 1992) to simulate the storm surges generated by these storms. We then search for black swan TCs, in terms of the joint wind and surge damage potential, in the generated large databases. Heavy rainfall is another important TC hazard and will be considered in a future study. We focus on three areas: Tampa Bay in the U.S., the Persian Gulf, and Darwin in Australia. Tampa Bay is highly vulnerable to storm surge as it is surrounded by shallow water and low-lying lands, much of which may be inundated by a storm tide of 6 m. High surges are generated by storms with a broad spectrum of characteristics in our synthetic database, although no large surge has been recorded historically as only one moderate storm passed by the area. Tampa black swans are identified as those that move northward parallel to the west Florida coast with high intensities and resonant with the Florida-shelf edge waves to generate extreme surges up to 10 m in Tampa Bay. The Arabian Sea area has sea surface temperatures warm enough to support the development of severe TCs, but TC development has been limited by low humidity and high wind shear, and only one recorded TC (super cyclonic storm Gonu in 2007) moved close to the Persian Gulf, making landfall in Oman and Iran. Our analysis shows that black swan TCs can originate within the Persian Gulf and make landfall with high intensities in populous places; extreme surges over 9 m for Abu Dubai and Doha and over 7 m for Dubai are possible. Darwin experienced immense devastation from Cyclone Tracy of 1974, but the damage was mainly due to the strong winds (the surge was only about 1.6 m). Our analysis includes extremely intense black swan TCs that make landfall just south of Darwin, generating surges above 10 m; these results may prompt the city to reconsider its TC risk. We are currently analyzing the join probability of the extreme wind and surge of these black swan TCs to more clearly assess their full damage potentials.

  17. Tropical cyclone-ocea~ interactions Isaac Ginis

    E-print Network

    Rhode Island, University of

    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

  18. OCEAN RESPONSE TO TROPICAL CYCLONE Isaac Ginis

    E-print Network

    Rhode Island, University of

    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

  19. Objective classification of historical tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Chenoweth, Michael

    2007-03-01

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

  20. APR-2 Tropical Cyclone Observations

    NASA Technical Reports Server (NTRS)

    Durden, S. L.; Tanelli, S.

    2011-01-01

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

  1. Polytropic process and tropical Cyclones

    E-print Network

    Romanelli, Alejandro; Rodríguez, Juan

    2013-01-01

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

  2. Intensity of prehistoric tropical cyclones

    NASA Astrophysics Data System (ADS)

    Nott, Jonathan F.

    2003-04-01

    Prediction of future tropical cyclone climate scenarios requires identification of quasi-periodicities at a variety of temporal scales. Extension of records to identify trends at century and millennial scales is important, but to date the emerging field of paleotempestology has been hindered by the lack of a suitable methodology to discern the intensity of prehistoric storms. Here a technique to quantify the central pressure of prehistoric tropical cyclones is presented in detail and demonstrated for the tropical southwest Pacific region. The importance of extending records to century time scales is highlighted for northeast Australia, where a virtual absence of category 5 cyclones during the 20th century stands in contrast to an active period of severe cyclogenesis during the previous century. Several land crossing storms during the 19th century achieved central pressures lower than that ever recorded historically and close to the theoretical thermodynamic limit of storms for the region. This technique can be applied to all tropical and subtropical regions globally and will assist in obtaining more realistic predictions for future storm scenarios with implications for insurance premiums, urban and infrastructural design, and emergency planning.

  3. Promoting the confluence of tropical cyclone research

    PubMed Central

    Marler, Thomas E

    2015-01-01

    Contributions of biologists to tropical cyclone research may improve by integrating concepts from other disciplines. Employing accumulated cyclone energy into protocols may foster greater integration of ecology and meteorology research. Considering experienced ecosystems as antifragile instead of just resilient may improve cross-referencing among ecological and social scientists. Quantifying ecosystem capital as distinct from ecosystem services may improve integration of tropical cyclone ecology research into the expansive global climate change research community. PMID:26480001

  4. Scaling of Tropical-Cyclone Dissipation

    E-print Network

    Osso, Albert; Llebot, J E

    2009-01-01

    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...

  5. Tropical Cyclones as a Critical Phenomenon

    E-print Network

    Corral, A

    2011-01-01

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

  6. 2015 WESTERN NORTH PACIFIC BASIN TROPICAL CYCLONE PREDICTIONS

    E-print Network

    Po, Lai-Man

    July 2015 2015 WESTERN NORTH PACIFIC BASIN TROPICAL CYCLONE PREDICTIONS 2015 TROPICAL CYCLONE University of Hong Kong have released their 2015 predictions for tropical cyclone formations and landfalls tropical cyclone landfalls in the Western North Pacific Basin, especially in the southern part

  7. HISTORICAL CLIMATOLOGY SERIES 6-2 TROPICAL CYCLONES OF THE NORTH ATLANTIC OCEAN, 1851 2006

    E-print Network

    #12;#12;HISTORICAL CLIMATOLOGY SERIES 6-2 TROPICAL CYCLONES OF THE NORTH ATLANTIC OCEAN, 1851.............................................................................................................................................. 3. Characteristics of Tropical Cyclones............................................................................................. 4. Classifications of Atlantic Tropical Cyclones

  8. LCSs in tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Rutherford, B.; Montgomery, M. T.

    2011-12-01

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

  9. Tropical Cyclone Nargis: 2008 - Duration: 45 seconds.

    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...

  10. Midlevel ventilation's constraint on tropical cyclone intensity

    E-print Network

    Tang, Brian Hong-An

    2010-01-01

    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 ...

  11. TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 115 (2015)

    E-print Network

    Smith, Roger K.

    2015-01-01

    TROPICAL CYCLONE RESEARCH REPORT TCRR 2: 1­15 (2015) Meteorological Institute Ludwig Maximilians University of Munich Why do model tropical cyclones grow progressively in size and decay in intensity after, CA 93943 Abstract: The long term behaviour of tropical cyclones in the prototype problem for cyclone

  12. Typhoon Vamei: An equatorial tropical cyclone formation

    NASA Astrophysics Data System (ADS)

    Chang, C.-P.; Liu, Ching-Hwang; Kuo, Hung-Chi

    2003-02-01

    Due to the diminishing Coriolis effect, the belt 300 km either side of the equator has been considered tropical cyclone-free. Typhoon Vamei, which developed near Singapore on 27 December 2001, was the first recorded tropical cyclone formation within 1.5 degrees of the equator. The development was the result of two interacting systems, a weak Borneo vortex that drifted into the southern tip of the South China Sea and remained there for four days, and a strong and persistent cold surge that created the large background cyclonic vorticity at the equator. The probability of a similar equatorial development is estimated to be once every 100-400 years.

  13. Raindrop Size Distribution Measurements in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Chen, L.; Gray, W. M.

    1985-01-01

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

  15. On the size distribution of Atlantic tropical cyclones

    E-print Network

    Emanuel, Kerry Andrew

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

  16. Modelling Atlantic Basin Tropical Cyclone Storm Tracks

    NASA Astrophysics Data System (ADS)

    Hardisty, F.; Carroll, D.

    2011-12-01

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

  17. 19Bulletin of the American Meteorological Society Tropical Cyclones and

    E-print Network

    Webster, Peter J.

    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 difficult in most of the tropical cyclone basins. However, in the two regions where reasonably reliable

  18. TROPICAL CYCLONE RESEARCH REPORT TCRR 5: 111 (2015)

    E-print Network

    Smith, Roger K.

    2015-01-01

    TROPICAL CYCLONE RESEARCH REPORT TCRR 5: 1­11 (2015) Meteorological Institute Ludwig Maximilians University of Munich Towards clarity on understanding tropical cyclone intensification Roger K. Smitha 1 paradigm of tropical cyclone intensification in the context of the prototype intensification problem, which

  19. REVIEW ARTICLE Synergistic effects of tropical cyclones on forest ecosystems

    E-print Network

    Xi, Weimin

    REVIEW ARTICLE Synergistic effects of tropical cyclones on forest ecosystems: a global synthesis Northeast Forestry University and Springer-Verlag Berlin Heidelberg 2015 Abstract Tropical cyclones to societies along their paths. Major tropical cyclones can infrequently move into the midaltitudes and inland

  20. Clouds in Tropical Cyclones ROBERT A. HOUZE JR.

    E-print Network

    Houze Jr., Robert A.

    REVIEW Clouds in Tropical Cyclones ROBERT A. HOUZE JR. Department of Atmospheric Sciences) ABSTRACT Clouds within the inner regions of tropical cyclones are unlike those anywhere else to have relatively weak downdrafts. Within the eyes of mature tropical cyclones, stratus clouds top

  1. Tropical cyclone genesis potential across palaeoclimates

    NASA Astrophysics Data System (ADS)

    Koh, J. H.; Brierley, C. M.

    2015-10-01

    The favourability of the mid-Pliocene, Last Glacial Maximum (LGM) and mid-Holocene for tropical cyclone formation is investigated in five climate models. This is measured by a genesis potential index, derived from large-scale atmospheric properties known to be related to storm formation. The mid-Pliocene and Last Glacial Maximum (LGM) were periods where carbon dioxide levels were higher and lower than preindustrial levels respectively, while the mid-Holocene differed primarily in its orbital configuration. The cumulative global genesis potential is found to be fairly invariant across the palaeoclimates in the multi-model mean. Despite this all ensemble members agree on coherent responses in the spatial patterns of genesis potential change. During the mid-Pliocene and LGM, changes in carbon dioxide led to sea surface temperature changes throughout the tropics, yet the potential intensity (a measure associated with maximum tropical cyclone strength) is calculated to be relatively insensitive to these changes. Changes in tropical cyclone genesis potential during the mid-Holocene are found to be asymmetric about the Equator: being reduced in the Northern Hemisphere but enhanced in the Southern Hemisphere. This is clearly driven by the altered seasonal insolation. Nonetheless, the enhanced seasonality drove localised changes in genesis potential, by altering the strength of monsoons and shifting the intertropical convergence zone. Trends in future tropical cyclone genesis potential are consistent neither between the five models studied nor with the palaeoclimate results. It is not clear why this should be the case.

  2. Citizen scientists analyzing tropical cyclone intensities

    NASA Astrophysics Data System (ADS)

    Hennon, Christopher C.

    2012-10-01

    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.

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

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

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

  4. Nuclear power plant risk from tropical cyclones

    SciTech Connect

    Gilmore, T.F. )

    1991-01-01

    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.

  5. A tropical cyclone application for virtual globes

    NASA Astrophysics Data System (ADS)

    Joseph Turk, F.; Hawkins, Jeff; Richardson, Kim; Surratt, Mindy

    2011-01-01

    Within the past ten years, a wide variety of publicly available environmental satellite-based data have become available to users and gained popular exposure in meteorological applications. For example, the Naval Research Laboratory (NRL) has maintained a well accepted web-based tropical cyclone (TC) website (NRL TC-Web) with a diverse selection of environmental satellite imagery and products covering worldwide tropical cyclones extending back to 1997. The rapid development of virtual globe technologies provides for an effective framework to efficiently demonstrate meteorological and oceanographic concepts to not only specialized weather forecasters but also to students and the general public. With their emphasis upon geolocated data, virtual globes represent the next evolution beyond the traditional web browser by allowing one to define how, where, and when various data are displayed and dynamically updated. In this article, we describe a virtual globe implementation of the NRL TC-Web satellite data processing system. The resulting NRL Tropical Cyclones on Earth (TC-Earth) application is designed to exploit the capabilities of virtual globe technology to facilitate the display, animation, and layering of multiple environmental satellite imaging and sounding sensors for effective visualization of tropical cyclone evolution. As with the NRL TC-Web, the TC-Earth application is a dynamic, realtime application, driven by the locations of active and historical tropical cyclones. TC-Earth has a simple interface that is designed around a series of placemarks that follow the storm track history. The position coordinates along the storm track are used to map-register imagery and subset other types of information, allowing the user a wide range of freedom to choose data types, overlay combinations, and animations with a minimum number of clicks. TC-Earth enables the user to quickly select and navigate to the storm of interest from the multiple TCs active at anytime around the world or to peruse data from archived storms.

  6. Increasing destructiveness of tropical cyclones over the past 30 years

    E-print Network

    Gray, Matthew

    Increasing destructiveness of tropical cyclones over the past 30 years Kerry Emanuel1 Theory1 dissipa- tion of power, integrated over the lifetime of the cyclone, and show that this index has warming may lead to an upward trend in tropical cyclone destructive potential, and--taking into account

  7. Model finds bigger, stronger tropical cyclones with warming seas

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2014-03-01

    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.

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

    PubMed

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-03-01

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

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

    PubMed Central

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-01-01

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

  11. Ocean barrier layers’ effect on tropical cyclone intensification

    PubMed Central

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

    2012-01-01

    Improving a tropical cyclone’s forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone’s path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are “quasi-permanent” features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity. PMID:22891298

  12. Impact Assessment of Tropical Cyclone Hud Hud on Coastal Region of Visakhapatnam, Andhra Pradesh, India

    NASA Astrophysics Data System (ADS)

    Vivek, G.; Srinivasa Kumar, T.

    2015-10-01

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

  13. Understanding and Forecasting Tropical Cyclone Intensity Change

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Patrick James

    1995-01-01

    This research investigates several issues pertaining to tropical cyclone intensity change. Previous research on tropical cyclone intensity change is reviewed in great detail. The applicability of upper-level forcing theories is questioned. Inner-core processes related to intensity change are studied, with particular attention on the relationship between the vertical profile of the tangential wind (v _{t}) field in the eyewall region and future pressure changes. It is hypothesized that a vertically conserved wind profile is conducive to fast intensification. Observations support this theory. By stratifying inner-core data into fast and slow developers, it is shown that fast developing tropical cyclones contain a more vertically stacked inner-core vortex than slow developers. It is also shown that a direct correlation exists between inner -core upper-level winds and tropical cyclone intensification, with the rate of intensification proportional to the magnitude and symmetry of upper-level v_{t}. . An alternative air-sea interaction theory is presented which incorporates boundary layer cooling. The buoyancy calculations include partial water-loading and ice micro -physics, and their relevance to CAPE calculations in the tropics is discussed. It is shown that the lateral extension of the eye, above a sloping eyewall, is the crucial component in maintaining the air-sea interaction despite boundary layer cooling. Implications on the maximum intensity a storm may achieve are discussed. A multiple regression scheme with intensity change as the dependent variable has been developed. The new scheme is titled the Typhoon Intensity Prediction Scheme (TIPS), and is similar to one used operationally at the National Hurricane Center. However, TIPS contains two major differences: it is developed for the western North Pacific Ocean, and utilizes digitized satellite data. It is shown that the satellite data can distinguish between fast and slow developing tropical cyclones. The importance of other statistical predictors (such as SSTs, wind shear, persistence, and climatology) to intensity change are also clarified. The statistics reveal threshold values useful to forecasters. It is shown that TIPS is competitive with the Joint Typhoon Warning Center.

  14. Multiscale Structures in Tropical Cyclone Boundary Layers

    NASA Astrophysics Data System (ADS)

    Foster, Ralph

    2015-04-01

    We present recent advances in the development of the resonant triad interaction model of large scale roll vortices in the tropical cyclone boundary layer. The relatively shallow, high shear and strong surface buoyancy flux conditions that characterize the tropical cyclone boundary layer make it an ideal environment for the formation of mixed shear/convection roll vortices. The most commonly documented rolls tend to align close to the mean wind direction and have aspect ratios (wavelength/depth) of near 2.5 to 4. Some observations suggest much smaller scale rolls are nearly ubiquitous in the near surface layer. Recent analyses of synthetic aperture radar images of the sea surface under tropical cyclones find nearly ubiquitous signatures of very large aspect ratio rolls, with wavelengths of order 10 km or greater. These rolls apparently extend from the surface into the lower troposphere. Our studies hypothesize that nonlinear triad wave-wave interactions are a likely candidate to explain the formation and persistence of these large aspect ratio modes, the variability in detectability of "standard roll vortices and a possible reason why such large scale rolls are not formed in mesoscale numerical models.

  15. Tropical cyclone intensities from satellite microwave data

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  16. Ocean Barrier Layers’ Effect on Tropical Cyclone Intensification

    SciTech Connect

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

    2012-09-04

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

  17. Diurnal analysis of intensity trends in Atlantic tropical cyclones

    E-print Network

    Kowch, Roman S

    2013-01-01

    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 ...

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

    E-print Network

    Murphy, Maurice D

    2008-01-01

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

  19. Space options for tropical cyclone hazard mitigation

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  20. A Conundrum of Tropical Cyclone Formation

    NASA Astrophysics Data System (ADS)

    Davis, C. A.

    2014-12-01

    This paper will address a conundrum that has emerged from recent research on tropical cyclone formation. Composite analyses and case studies suggest that prior to genesis, the atmosphere presents a mid-tropospheric vortex that is strong compared to the cyclonic circulation in the boundary layer. Accompanying this vortex is near saturation from the boundary layer through at least 5 km, sometimes more, and a nearly balanced weak negative temperature anomaly below the vortex and stronger positive temperature anomaly above. This thermodynamic state is one of high moisture but low buoyancy for lifted parcels (i.e. low convective available potential energy). However, observations also suggest that widespread deep convection accompanies genesis, with cloud top temperatures becoming colder near the time of genesis. This is seemingly at odds with in situ observations of thermodynamic characteristics prior to genesis. Progress toward understanding the apparent contradiction can be made by realizing that the existence of a moist, relatively stable vortex, and deep convective clouds are not necessarily coincident in space and time. This is demonstrated by a detailed analysis of the two days leading up to the formation of Atlantic tropical cyclone Karl on 14 September. Karl featured a relatively long gestation period characterized initially by a marked misalignment of mid-tropospheric and surface cyclonic circulations. The mid-tropospheric vortex strengthened due to a pulse of convection earlier on 13 September. Meanwhile, the near-surface vortex underwent a precession around the mid-tropospheric vortex as the separation between the two decreased. The eruption of convection around midnight on 14 September, 18 hours prior to declaration on a TC, occurred in the center of the nearly-aligned vortex, contained a mixture of shallow and deep convection and resulted in spin-up over a deep layer, but particularly at the surface. Prior to genesis, the most intense deep convection was located at least 200 km from the center.

  1. Tropical Cyclone Interactions Within Central American Gyres

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Emergency Department Presentations following Tropical Cyclone Yasi

    PubMed Central

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

    2015-01-01

    Introduction Emergency departments see an increase in cases during cyclones. The aim of this study is to describe patient presentations to the Emergency Department (ED) of a tertiary level hospital (Townsville) following a tropical cyclone (Yasi). Specific areas of focus include changes in: patient demographics (age and gender), triage categories, and classification of diseases. Methods Data were extracted from the Townsville Hospitals ED information system (EDIS) for three periods in 2009, 2010 and 2011 to coincide with formation of Cyclone Yasi (31 January 2011) to six days after Yasi crossed the coast line (8 February 2012). The analysis explored the changes in ICD10-AM 4-character classification and presented at the Chapter level. Results There was a marked increase in the number of patients attending the ED during Yasi, particularly those aged over 65 years with a maximum daily attendance of 372 patients on 4 Feb 2011. The most marked increases were in: Triage categories - 4 and 5; and ICD categories - diseases of the skin and subcutaneous tissue (L00-L99), and factors influencing health care status (Z00-Z99). The most common diagnostic presentation across all years was injury (S00-T98). Discussion There was an increase in presentations to the ED of TTH, which peaked in the first 24 – 48 hours following the cyclone and returned to normal over a five-day period. The changes in presentations were mostly an amplification of normal attendance patterns with some altered areas of activity. Injury patterns are similar to overseas experience. PMID:26111010

  3. Tropical cyclone forcing of sediment transport in Taiwan

    NASA Astrophysics Data System (ADS)

    Galewsky, J.; Stark, C.; Dadson, S.; Sobel, A.

    2005-12-01

    Erosion in mountain belts is commonly assumed to be jointly controlled by relief and annual mean precipitation. This assumption may be invalid in the Tropics, where much of the heavy rainfall is associated with tropical cyclones. Tropical cyclone rainfall is spatially and temporally intermittent and is dependent on topography in more complex ways than the storms that affect mid-latitude mountain belts. The links between tropical cyclone rainfall and landscape evolution in subtropical mountain belts are poorly understood. Here we use observations of precipitation and suspended sediment concentration from Taiwan along with numerical models of tropical cyclone dynamics to assess the links between tropical cyclone circulation, topography, precipitation, and sediment transport during Typhoons Herb (1996) and Toraji (2001). We show that (1) the sediment transport in the Kaoping River was driven by orographically enhanced tropical cyclone rainfall during both typhoons; (2) sediment transport in the Hualien River was controlled by tropical cyclone eyewall processes during Toraji; (3) sediment transport in the Choshui River, while largely controlled by coseismic effects of the 1999 Chichi earthquake, was enhanced by orographic effects during Toraji.

  4. An Interactive Parallel Coordinates Technique Applied to a Tropical Cyclone Climate

    E-print Network

    Swan II, J. Edward

    An Interactive Parallel Coordinates Technique Applied to a Tropical Cyclone Climate Analysis Chad A is a tropical cyclone, defined as a warm-core non-frontal synoptic-scale cyclone,4 originating over tropical or subtropical waters, with organized thunderstorms5 and a closed surface wind circulation. Tropical cyclones

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Cyclones are regarded as one of the most dangerous meteorological phenomena of the tropical region. The probability of landfall of a tropical cyclone depends on its movement (trajectory). Analysis of trajectories of tropical cyclones could be useful for identifying potentially predictable characteristics. There is long history of analysis of tropical cyclones tracks. A common approach is using different clustering techniques to group the cyclone tracks on the basis of certain characteristics. Various clustering method have been used to study the tropical cyclones in different ocean basins like western North Pacific ocean (Elsner and Liu, 2003; Camargo et al., 2007), North Atlantic Ocean (Elsner, 2003; Gaffney et al. 2007; Nakamura et al., 2009). In this study, tropical cyclone tracks in the North Indian Ocean basin, for the period 1961-2010 have been analyzed and grouped into clusters based on their spatial characteristics. A tropical cyclone trajectory is approximated as an open curve and described by its first two moments. The resulting clusters have different centroid locations and also differently shaped variance ellipses. These track characteristics are then used in the standard clustering algorithms which allow the whole track shape, length, and location to be incorporated into the clustering methodology. The resulting clusters have different genesis locations and trajectory shapes. We have also examined characteristics such as life span, maximum sustained wind speed, landfall, seasonality, many of which are significantly different across the identified clusters. The clustering approach groups cyclones with higher maximum wind speed and longest life span in to one cluster. Another cluster includes short duration cyclonic events that are mostly deep depressions and significant for rainfall over Eastern and Central India. The clustering approach is likely to prove useful for analysis of events of significance with regard to impacts.

  6. Tropical cyclone triggering of sediment discharge in Taiwan

    NASA Astrophysics Data System (ADS)

    Galewsky, J.; Stark, C. P.; Dadson, S.; Wu, C.-C.; Sobel, A. H.; Horng, M.-J.

    2006-09-01

    The impact of tropical cyclones on precipitation variability and surface processes in Taiwan is studied using suspended sediment and river discharge data along with a meteorological model of tropical cyclone dynamics. The interactions between tropical cyclones and topography produce distinctive, localized patterns of heavy precipitation that can trigger high sediment discharge in Taiwan's rivers. We focus on Typhoon Toraji, which made landfall in Taiwan on 30 July 2001 and was the first major tropical cyclone to affect Taiwan after the 1999 Chichi earthquake. The passage of the tropical cyclone eye over the east coast of Taiwan produced intense rainfall (>100 mm h-1) for a short period (about 2 hours), triggering the highest sediment concentration ever recorded on the Hualien River. Orographic effects localized heavy rainfall (between 10 and 50 mm h-1) over the southwestern slopes of the Central Mountain Range, triggering high sediment discharge on the Kaoping River and flushing landslide debris produced during the Chichi earthquake into the Choshui River. We show that a range of atmospheric processes, with distinctive spatial variability and varying degrees of coupling to topography, interacted with tectonic processes of limited spatial extent to produce the overall sediment discharge from Taiwan during Typhoon Toraji. Landscape evolution models may need to be modified to account for the distinctive patterns of localized rainfall in tropical mountain belts. Furthermore, the links between tropical cyclones and topography suggest the potential for a range of previously unrecognized feedbacks between tectonics and climate in tropical mountain belts.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. 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, 6 of which became hurricanes East Pacific Ocean: 15 tropical storms, 8 of which became hurricanes Central Pacific Ocean: 4 tropical storms, 2 of which became hurricanes Over a typical 2-year period, the U

  9. Tropical cyclone size in observations and in radiative-convective equilibrium

    E-print Network

    Chavas, Daniel Robert

    2013-01-01

    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 ...

  10. Animation of Flood Potential from Two Australian Tropical Cyclones - Duration: 6 seconds.

    NASA Video Gallery

    Merged precipitation data from NASA-JAXA's Tropical Rainfall Measuring Mission (TRMM) and other satellites was used to calculate flood potential withrainfall from Tropical Cyclone Lam and Tropical ...

  11. Impacts of tropical cyclones on Fiji and Samoa

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Weather and climate hazards have significant impacts on Pacific Island Countries. Costs of hazards such as tropical cyclones can be astronomical making enormous negative economic impacts on developing countries. We highlight examples of extreme weather events which have occurred in Fiji and Samoa in the last few decades and have caused major economic and social disruption in the countries. Destructive winds and torrential rain associated with tropical cyclones can bring the most damaging weather conditions to the region causing economic and social hardship, affecting agricultural productivity, infrastructure and economic development which can persist for many years after the initial impact. Analysing historical data, we describe the impacts of tropical cyclones Bebe and Kina on Fiji. Cyclone Bebe (October 1972) affected the whole Fiji especially the Yasawa Islands, Viti Levu and Kadavu where hurricane force winds have been recorded. Nineteen deaths were reported and damage costs caused by cyclone Bebe were estimated as exceeding F20 million (F 1972). Tropical cyclone Kina passed between Fiji's two main islands of Viti Levu and Vanua Levu, and directly over Levuka on the night of 2 January 1993 with hurricane force winds causing extensive damage. Twenty three deaths have been reported making Kina one of the deadliest hurricanes in Fiji's recent history. Severe flooding on Viti Levu, combined with high tide and heavy seas led to destruction of the Sigatoka and Ba bridges, as well as almost complete loss of crops in Sigatoka and Navua deltas. Overall, damage caused by cyclone Kina was estimated as F170 million. In Samoa, we describe devastation to the country caused by tropical cyclones Ofa (February 1990) and Val (December 1991) which were considered to be the worst cyclones to affect the Samoan islands since the 1889 Apia cyclone. In Samoa, seven people were killed due to cyclone Ofa, thousands of people were left homeless and entire villages were destroyed. Damage on Samoa totalled to US130 million. Cyclone Val caused damage and destruction to 95% of houses in Samoa and severe crop damage; total damage was estimated as US200 million. Recently, severe tropical cyclone Evan affected Samoa and Fiji (December 2012). Significant progress in operational tropical cyclone forecasting has been achieved over the past few decades which resulted in improving early warning system but death toll attributed to cyclones is still high - at least 14 deaths in Samoa are related to cyclone Evan (luckily, no death reports in Fiji). Cyclone-related economic losses also remain very high making significant negative impact on economies of the countries. Preliminary assessment of damage caused by cyclone Evan in Fiji indicates loses of about 75.29 million. By the end of this century projections suggest decreasing numbers of tropical cyclones but a possible shift towards more intense categories. In addition, geographic shifts in distribution of tropical cyclone occurrences caused by warming of the atmospheric and oceanic environment are possible. This should be taken in consideration by authorities of the Pacific Island Countries when developing adaptation strategies to increasing tropical cyclone risk due to climate change.

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

    NASA Video Gallery

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

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

    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). ...

  14. The effects of ocean eddies on tropical cyclones

    E-print Network

    Miltenberger, Alexander Reid

    2012-01-01

    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 ...

  15. Influence of upper ocean stratification interannual variability on tropical cyclones

    E-print Network

    Vincent, Emmanuel M.

    Climate modes, such as the El Niño Southern Oscillation (ENSO), influence Tropical Cyclones (TCs) interannual activity through their effect on large-scale atmospheric environment. These climate modes also induce interannual ...

  16. Seasonal versus permanent thermocline warming by tropical cyclones

    E-print Network

    Ferrari, Raffaele

    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 ...

  17. Tropical cyclone precipitation risk in the Southern United States

    E-print Network

    Shedd, Sandra Michael

    2015-01-01

    This thesis works to evaluate the new rainfall algorithm that is used to simulate longterm tropical cyclone precipitation (TCP) climatology throughout the southeastern United States. The TCP climatology is based on a fleet ...

  18. Tropical Cyclone Trend Analysis using Enhanced Parallel Coordinates and Statistical Analytics

    E-print Network

    Swan II, J. Edward

    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

  19. Cloud to ground lightning in tropical cyclone: a study of 34 West Atlantic tropical cyclones from 1986-1996 

    E-print Network

    Coyne, John Michael

    2001-01-01

    Cloud to ground (CG) lightning characteristics and patterns were investigated for 34 tropical cyclones for the time period 1986 to 1996. Spatial analysis of CG lightning relative to both compass directions and the direction of motion were compiled...

  20. Tropical cyclone intensity change. A quantitative forecasting scheme

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

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

    SciTech Connect

    Fitzpatrick, M.E.

    1992-01-01

    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.

  2. Global climate change and tropical cyclones

    SciTech Connect

    Lighthill, J. ); Holland, G. ); Gray, W.; Landsea, C. ); Craig, G. ); Evans, J. ); Kurihara, Yoshio ); Guard, C. )

    1994-11-01

    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.

  3. Inducing Tropical Cyclones to Undergo Brownian Motion

    NASA Astrophysics Data System (ADS)

    Hodyss, D.; McLay, J.; Moskaitis, J.; Serra, E.

    2014-12-01

    Stochastic parameterization has become commonplace in numerical weather prediction (NWP) models used for probabilistic prediction. Here, a specific stochastic parameterization will be related to the theory of stochastic differential equations and shown to be affected strongly by the choice of stochastic calculus. From an NWP perspective our focus will be on ameliorating a common trait of the ensemble distributions of tropical cyclone (TC) tracks (or position), namely that they generally contain a bias and an underestimate of the variance. With this trait in mind we present a stochastic track variance inflation parameterization. This parameterization makes use of a properly constructed stochastic advection term that follows a TC and induces its position to undergo Brownian motion. A central characteristic of Brownian motion is that its variance increases with time, which allows for an effective inflation of an ensemble's TC track variance. Using this stochastic parameterization we present a comparison of the behavior of TCs from the perspective of the stochastic calculi of Itô and Stratonovich within an operational NWP model. The central difference between these two perspectives as pertains to TCs is shown to be properly predicted by the stochastic calculus and the Itô correction. In the cases presented here these differences will manifest as overly intense TCs, which, depending on the strength of the forcing, could lead to problems with numerical stability and physical realism.

  4. Influence of the zonal mean circulation on tropical cyclone frequency

    NASA Astrophysics Data System (ADS)

    Ballinger, A. P.; Held, I.; Merlis, T. M.; Zhao, M.

    2012-12-01

    Aquaplanet general circulation modeling experiments have been useful tools for understanding the response of large scale circulations to climate change. Here, we extend this approach to investigate the influence of the zonal mean circulation on tropical cyclone frequency. GFDL's High Resolution Atmospheric Model (HiRAM, ~50km horizontal resolution) has previously been shown to simulate tropical cyclone (TC) statistics consistent with observations (e.g. Zhao et al., 2009, 2010). A new set of experiments have been designed to investigate the relationship between the large-scale dynamic and thermodynamic fields and tropical cyclone frequency. We perform HiRAM simulations in two different aquaplanet configurations: one with a fixed, zonally-symmetric SST boundary condition and the other with interactive SSTs determined by a slab ocean boundary condition. By varying the latitude of maximum SST in the fixed SST runs or the prescribed value of cross-equatorial ocean heat transport in the slab runs, the ITCZ can be shifted further to the north or south. A TC detection and tracking algorithm computes the various storm statistics associated with the different experiments, and we find that more tropical cyclones develop as the latitude of the ITCZ moves poleward. We explore the relationship between genesis frequency and the large scale circulation, such as the strength of the Hadley Cell and position of the ITCZ. These results may have implications for tropical cyclone frequency in a changing climate.

  5. Sensitivity of Tropical Cyclone Intensity to Ventilation in an Axisymmetric Model

    E-print Network

    Tang, Brian

    The sensitivity of tropical cyclone intensity to ventilation of cooler, drier air into the inner core is examined using an axisymmetric tropical cyclone model with parameterized ventilation. Sufficiently strong ventilation ...

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

    E-print Network

    Hales, Billy

    2012-07-16

    ....................................................................................... 2 Objectives ........................................................................................ 2 II SPIT GEOMORPHOLOGY AND TROPICAL CYCLONE IMPACTS... .............................................................................................. 4 Spits ................................................................................................. 4 Spit Geomorphology ................................................................. 4 Spit Evolution...

  7. Temporal clustering of tropical cyclones and its ecosystem impacts

    PubMed Central

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

    2011-01-01

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

  8. Thermodynamic Aspects of Tropical Cyclone Formation

    NASA Astrophysics Data System (ADS)

    Wang, Z.

    2012-12-01

    The thermodynamic aspects of tropical cyclone (TC) formation near the center of the wave pouch, a region of approximately closed Lagrangian circulation within the wave critical layer, are examined through diagnoses of a high-resolution numerical simulation and dropsonde data from a recent field campaign. It is found that the meso-? area near the pouch center is characterized by high saturation fraction, small difference in equivalent potential temperature (?e) between the surface and the middle troposphere, and a short incubation time scale. Updrafts tend to be more vigorous in this region, presumably due to reduced dry air entrainment, while downdrafts are not suppressed. The thermodynamic conditions near the pouch center are thus critically important for TC formation. The balanced responses to convective and stratiform heating at the pre-genesis stage are examined using the Sawyer-Eliassen equation. Deep convection is concentrated near the pouch center. The strong radial and vertical gradients of latent heat release effectively force the transverse circulation and spin up a surface proto-vortex near the pouch center. Stratiform heating induces modest mid-level inflow and very weak low-level outflow, which contributes to the mid-level spin-up without substantially spinning down the low-level circulation. The analysis of dropsonde data shows that the mid-level ?e increases significantly near the pouch center one to two days prior to genesis but changes little away from the pouch center. This may indicate convective organization and the impending TC genesis. It also suggests that the critical information of TC genesis near the pouch center may be masked out if a spatial average is taken over the pouch scale. Time-radius plots of (a) saturation fraction (SF; units: %), (b) ?e difference between 950 mb and 700 mb (950 mb "minus" 700 hPa; units: K), and (c) ?m in the numerical model simulation of Felix.

  9. Satellite-based Tropical Cyclone Monitoring Capabilities

    NASA Astrophysics Data System (ADS)

    Hawkins, J.; Richardson, K.; Surratt, M.; Yang, S.; Lee, T. F.; Sampson, C. R.; Solbrig, J.; Kuciauskas, A. P.; Miller, S. D.; Kent, J.

    2012-12-01

    Satellite remote sensing capabilities to monitor tropical cyclone (TC) location, structure, and intensity have evolved by utilizing a combination of operational and research and development (R&D) sensors. The microwave imagers from the operational Defense Meteorological Satellite Program [Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS)] form the "base" for structure observations due to their ability to view through upper-level clouds, modest size swaths and ability to capture most storm structure features. The NASA TRMM microwave imager and precipitation radar continue their 15+ yearlong missions in serving the TC warning and research communities. The cessation of NASA's QuikSCAT satellite after more than a decade of service is sorely missed, but India's OceanSat-2 scatterometer is now providing crucial ocean surface wind vectors in addition to the Navy's WindSat ocean surface wind vector retrievals. Another Advanced Scatterometer (ASCAT) onboard EUMETSAT's MetOp-2 satellite is slated for launch soon. Passive microwave imagery has received a much needed boost with the launch of the French/Indian Megha Tropiques imager in September 2011, basically greatly supplementing the very successful NASA TRMM pathfinder with a larger swath and more frequent temporal sampling. While initial data issues have delayed data utilization, current news indicates this data will be available in 2013. Future NASA Global Precipitation Mission (GPM) sensors starting in 2014 will provide enhanced capabilities. Also, the inclusion of the new microwave sounder data from the NPP ATMS (Oct 2011) will assist in mapping TC convective structures. The National Polar orbiting Partnership (NPP) program's VIIRS sensor includes a day night band (DNB) with the capability to view TC cloud structure at night when sufficient lunar illumination exits. Examples highlighting this new capability will be discussed in concert with additional data fusion efforts.

  10. EOS, TRANSACTIONS, AMERICAN GEOPHYSICAL UNION Each year, tropical cyclones and hurri-

    E-print Network

    Wang, Chunzai

    EOS, TRANSACTIONS, AMERICAN GEOPHYSICAL UNION Each year, tropical cyclones and hurri- canes leave tropical cyclones and hurricanes will form and strike will help societies bet- ter prepare for adverse- cal cyclones can form and develop in both the tropical North Atlantic and eastern North Pacific oceans

  11. The Effect of Tropical Cyclone Characteristics on U.S. Landfall Probability

    E-print Network

    Rowell, Eric C.

    The Effect of Tropical Cyclone Characteristics on U.S. Landfall Probability Julie Lederer July 28, 2008 Abstract When a tropical cyclone threatens the coastline, decision makers can take prepara- tory. Regnier and Harr combine their decision model with a Markov model of tropical cyclone motion derived from

  12. Tropical cyclone evolution in a minimal axisymmetric model Christoph W. Schmidta and Roger K. Smitha

    E-print Network

    Smith, Roger K.

    Tropical cyclone evolution in a minimal axisymmetric model revisited Christoph W. Schmidta for a tropical cyclone is described. The model is used to revisit some fundamental aspects of vortex behaviour in the prototype problem for tropical cyclone intensification. After rapidly intensifying to a mature phase

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

    E-print Network

    Gerstoft, Peter

    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

  14. Research Brief 2014/03 Verification of Forecasts of Tropical Cyclone Activity

    E-print Network

    Po, Lai-Man

    Research Brief 2014/03 Verification of Forecasts of Tropical Cyclone Activity in the Australian-time forecasts of the annual number of tropical cyclones (TCs) affecting the Australian region (90°E-160°E, 40°SM) (Table 2). Table 2. Summary of 2013/14 tropical cyclones in the Australian region. Entire Australian

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

    E-print Network

    Wang, Yuqing

    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

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

    E-print Network

    Li, Tim

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

  17. Validating Atmospheric Reanalysis Data Using Tropical Cyclones as Thermometers James P. Kossin

    E-print Network

    Kossin, James P.

    1 Validating Atmospheric Reanalysis Data Using Tropical Cyclones as Thermometers James P. Kossin tropical cyclones as thermometers. Bull. Amer. Meteor. Soc. doi:10.1175/BAMS-D-14-00180, in press. Capsule Tropical cyclones are used as traveling thermometers to globally sample upper-tropospheric temperatures

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

    E-print Network

    Tang, Brian

    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

  19. Maintenance of Tropical Cyclone Bill (1988) after landfall

    NASA Astrophysics Data System (ADS)

    Xu, Yamei

    2013-08-01

    The mechanism for the maintenance of Tropical Cyclone Bill (1988) after landfall is investigated through a numerical simulation. The role of the large-scale environmental flow is examined using a scale separation technique, which isolates the tropical cyclone from the environmental flow. The results show that Bill was embedded in a deep easterly-southeasterly environmental flow to the north-northeast of a large-scale depression and to the southwest of the western Pacific subtropical high. The depression had a quasibarotropic structure in the mid-lower troposphere and propagated northwestward with a speed similar to the northwestward movement of Bill. The moisture budgets associated with both the large-scale and the tropical cyclone scale motions indicate that persistent low-level easterly-southeasterly flow transported moisture into the inner core of the tropical cyclone. The low-level circulation of the tropical cyclone transported moisture into the eyewall to support eyewall convection, providing sufficient latent heating to counteract energy loss due to surface friction and causing the storm to weaken relatively slowly after landfall. Warming and a westward extension of the upper-level easterly flow led to westward propagation of the environmental flow in the mid-lower troposphere. As a result, Bill was persistently embedded in an environment of deep easterly flow with high humidity, weak vertical wind shear, convergence in the lower troposphere, and divergence in the upper troposphere. These conditions are favorable for both significant intensification prior to landfall and maintenance of the tropical cyclone after landfall.

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

    NASA Astrophysics Data System (ADS)

    Spineanu, F.; Vlad, M.

    2014-01-01

    The large scale atmospheric vortices (tropical cyclones, tornadoes) are complex physical systems combining thermodynamics and fluid-mechanical processes. The late phase of the evolution towards stationarity consists of the vorticity concentration, a well known tendency to self-organization , an universal property of the two-dimensional fluids. It may then be expected that the stationary state of the tropical cyclone has the same nature as the vortices of many other systems in nature: ideal (Euler) fluids, superconductors, Bose-Einsetin condensate, cosmic strings, etc. Indeed it was found that there is a description of the atmospheric vortex in terms of a classical field theory. It is compatible with the more conventional treatment based on conservation laws, but the field theoretical model reveals properties that are almost inaccessible to the conventional formulation: it identifies the stationary states as being close to self-duality. This is of highest importance: the self-duality is known to be the origin of all coherent structures known in natural systems. Therefore the field theoretical (FT) formulation finds that the cuasi-coherent form of the atmospheric vortex (tropical cyclone) at stationarity is an expression of this particular property. In the present work we examine a strong property of the tropical cyclone, which arises in the FT formulation in a natural way: the equality of the masses of the particles associated to the matter field and respectively to the gauge field in the FT model is translated into the equality between the maximum radial extension of the tropical cyclone and the Rossby radius. For the cases where the FT model is a good approximation we calculate characteristic quantities of the tropical cyclone and find good comparison with observational data.

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

    NASA Astrophysics Data System (ADS)

    Moore, Todd W.

    2015-05-01

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

  2. 3574 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 46, NO. 11, NOVEMBER 2008 Objective Measures of Tropical Cyclone Structure

    E-print Network

    Ritchie, Elizabeth

    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

  3. Impact of Vertical Wind Shear on Tropical Cyclone Rainfall

    NASA Technical Reports Server (NTRS)

    Cecil, Dan; Marchok, Tim

    2014-01-01

    While tropical cyclone rainfall has a large axisymmetric component, previous observational and theoretical studies have shown that environmental vertical wind shear leads to an asymmetric component of the vertical motion and precipitation fields. Composites consistently depict a precipitation enhancement downshear and also cyclonically downwind from the downshear direction. For consistence with much of the literature and with Northern Hemisphere observations, this is subsequently referred to as "Downshear-Left". Stronger shear magnitudes are associated with greater amplitude precipitation asymmetries. Recent work has reinforced the prior findings, and explored details of the response of the precipitation and kinematic fields to environmental vertical wind shear. Much of this research has focused on tropical cyclones away from land, to limit the influence of other processes that might distort the signal related to vertical wind shear. Recent evidence does suggest vertical wind shear can also play a major role in precipitation asymmetries during and after landfall.

  4. A QuikSCAT climatology of tropical cyclone size

    E-print Network

    Chavas, Daniel Robert

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

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

    E-print Network

    Broccoli, Anthony J.

    I I Comments on "Global Climate Change and Tropical Cyclones": Part II 1 ANTHONY J. BROCCOLI; Broccoli and Manabe 1990). In addition, the geographical distributions, seasonality, and interannual variability of simulated Comments on "Global Climate Change storms are similar to those observed (Broccoli

  6. TROPICAL CYCLONE RESEARCH REPORT TCRR 15-1: 118 (2015)

    E-print Network

    Smith, Roger K.

    2015-01-01

    are given in terms of vorticity dynamics. The roll up of low-level absolute vorticity associated convection near the circulation centre. The development of the low that didn't achieve tropical cyclone lows over land (often referred to as monsoon depressions) as well as the role of deep convection

  7. Forced, Balanced Model of Tropical Cyclone Intensification Wayne H. Schubert,

    E-print Network

    Schubert, Wayne H.

    Forced, Balanced Model of Tropical Cyclone Intensification Wayne H. Schubert, Christopher J. Slocum to the prediction of potential vorticity (PV) and the inversion of this PV to obtain the balanced wind and mass; shallow water model; wave-vortex approx- imation 1. Introduction The Eliassen (1951) balanced vortex

  8. A 6000 year tropical cyclone record from Western Australia

    NASA Astrophysics Data System (ADS)

    Nott, Jonathan

    2011-03-01

    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.

  9. Observation, Analysis and Prediction of Atlantic tropical Cyclone Formation (Invited)

    NASA Astrophysics Data System (ADS)

    Davis, C. A.; Torn, R. D.

    2010-12-01

    During the 2010 Atlantic hurricane season, significant observational and prediction resources were used to study the process of tropical cyclone formation and its predictability. Observations, in addition to those routinely available from satellites, were provided by aircraft from NOAA, NASA and NSF participating jointly in an effort to understand tropical cyclone formation and the sometimes rapid transformation of a weak cyclone into a strong tropical cyclone. The NSF-sponsored PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) is focused on tropical (easterly) waves over the Atlantic and seeks observations of the general wave trough region to distinguish characteristics of waves that develop into tropical cyclones from those that do not. Among the PREDICT hypotheses is that recirculation regions, defined by closed lower-tropospheric cyclonic circulations in a frame of reference moving with the wave, allow air parcels to be isolated from dry air, thus increasing their humidity over time. Deep moist convection in air with high humidity through a deep layer of the troposphere, in a region of strong rotation, produces comparatively weak or more localized downdrafts and tends to favor inflow and spinup of cyclonic circulation. Observations from dropsondes and an array of other instruments on the NSF/NCAR G-V aircraft sampled air inside and outside the recirculation regions as well as other structural characteristics of several tropical waves. These observations are synthesized to evaluate the central PREDICT hypotheses. One of the sub-hypotheses of PREDICT is that these recirculation regions, or their boundaries, can be the source of significant initial condition error, which limits the predictability of these disturbances. Moreover, it is also possible that uncertainties outside the recirculation region could have large impact on forecasts. We explore these possibilities using an ensemble Kalman filter analysis and forecasting system that is run with and without special field observations to understand inherited uncertainty in the background, how much this uncertainty can be reduced by observations in location where the forecast is sensitive to the initial conditions, particularly in the wave trough region, and how these initial condition uncertainties manifest themselves in forecasts. Finally, results from high-resolution forecasts used to predict formation and early intensification stages of Atlantic storms during the 2010 season will be highlighted.

  10. Dynamically Downscaling Precipitation from Extra-Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Champion, A.; Hodges, K.; Bengtsson, L.

    2012-04-01

    Recent flooding events experienced by the UK and Western Europe have highlighted the potential disruption caused by precipitation associated with extra-tropical cyclones. The question as to the effect of a warming climate on these events also needs to be addressed to determine whether such events will become more frequent or more intense in the future. The changes in precipitation can be addressed through the use of Global Climate Models (GCMs), however the resolution of GCMs are often too coarse to drive hydrological models, required to investigate any flooding that may be associated with the precipitation. The changes to the precipitation associated with extra-tropical cyclones are investigated by tracking cyclones in two resolutions of the ECHAM5 GCM, T213 and T319 for 20th and 21st century climate simulations. It is shown that the intensity of extreme precipitation associated with extra-tropical cyclones is predicted to increase in a warmer climate at both resolutions. It was also found that the increase in resolution shows an increase in the number of extreme events for several fields, including precipitation; however it is also seen that the magnitude of the response is not uniform across the seasons. The tails of the distributions are investigated using Extreme Value Theory (EVT) using a Generalised Pareto Distribution (GPD) with a Peaks over Threshold (POT) method, calculating return periods for given return levels. From the cyclones identified in the T213 resolution of the GCM a small number of cyclones were selected that pass over the UK, travelling from the South-West to the North-East. These are cyclones that are more likely to have large amounts of moisture associated with them and therefore potentially being associated with large precipitation intensities. Four cyclones from each climate were then selected to drive a Limited Area Model (LAM), to gain a more realistic representation of the precipitation associated with each extra-tropical cyclone. The suitability of the LAM for downscaling was evaluated by running the LAM for the events of June and July 2007 (UK floods) and comparing the output to observations. The results from this comparison provide confidence that the model is able of reproducing realistic intensities for extreme precipitation events. Whilst this method does not allow for a robust comparison between the climates it does for allow for an analysis of the method, and whether dynamically downscaling individual events is suitable. It was found that by nesting the LAM within the GCM, large increases in the precipitation intensities were seen, as well as gaining a greater temporal resolution. Analysis of more events will allow a more robust comparison between climates.

  11. Tropical Cyclone Induced Air-Sea Interactions Over Oceanic Fronts

    NASA Astrophysics Data System (ADS)

    Shay, L. K.

    2012-12-01

    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.

  12. Tropical Cyclone Diurnal Cycle as Observed by TRMM

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  13. Relationship between tropical cyclones and the distribution of sea turtle nesting

    E-print Network

    Turner, Monica G.

    ORIGINAL ARTICLE Relationship between tropical cyclones and the distribution of sea turtle nesting the distribution of existing sea turtle nesting sites and historical patterns of tropical cyclone events to investigate whether cyclones influence the current distribution of sea turtle nesting sites. The results

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

    E-print Network

    Ritchie, Elizabeth

    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

  15. Dendrotempestology and the Isotopic Record of Tropical Cyclones in Tree Rings

    E-print Network

    Grissino-Mayer, Henri D.

    Dendrotempestology and the Isotopic Record of Tropical Cyclones in Tree Rings of the SoutheasternUnited States Henri D. Grissino-Mayer, Dana L. Miller, and Claudia I. Mora 1 Introduction Tropical cyclones (TCs) (hurricanes, typhoons, and cyclones) are considered the natural hazard with the greatest potential for loss

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

    E-print Network

    Rhode Island, University of

    Effects of surface heat flux-induced sea surface temperature changes on tropical cyclone intensity cyclone-induced sea surface cooling is small compared to that caused by turbulent mixing and cold water entrainment into the upper ocean mixed-layer. This study shows that tropical cyclone-induced surface heat

  17. The Fertilisation of the Sea by a Tropical Cyclone

    NASA Astrophysics Data System (ADS)

    Lin, I.; Liu, T.; Wu, C.; Wong, G.; Hu, C.

    2002-12-01

    Traditionally accepted mechanisms of nutrient supply to the upper ocean are insufficient for supporting the new production in the oligotrophic ocean estimated from geochemical tracers1-3. This paradox, whose resolution is critical for a full understanding of the global carbon cycle, has generated an intensive search for sources of allochthonous nutrients to the upper ocean3-9. Episodic injections of nutrients as a result of enhanced vertical mixing and upwelling across the nutricline pumped by tropical cyclones, is a possibility that has been much speculated yet largely undocumented by direct observations10-13. Here we use a combination of newly available remote sensors and show that the impact of a moderate cyclone can be far reaching. In July 2000, tropical cyclone Kai-Tak transgressed through the South China Sea (SCS). It caused up to 300 times increase in phytoplankton biomass and 9,aC reduction of sea surface temperature. A minimum of 0.8 Mt of carbon, equivalent to 2-4% of the annual new production in the oligotrophic SCS, has been generated. Given that there are in average 14 tropical depressions/cyclones passing SCS annually, their contribution to the SCS carbon cycle is significant.

  18. SUMMARY OF 2012 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHORS' SEASONAL AND TWO-WEEK FORECASTS

    E-print Network

    Connors, Daniel A.

    SUMMARY OF 2012 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHORS' SEASONAL AND TWO. It was notable for having a very large number of weak, high latitude tropical cyclones but only one major (MHD) (3.9) 3 4 5 0.25 6% Accumulated Cyclone Energy (ACE) (92) 70 80 99 129 140% Net Tropical Cyclone

  19. SUMMARY OF 2013 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHORS' SEASONAL AND TWO-WEEK FORECASTS

    E-print Network

    Connors, Daniel A.

    SUMMARY OF 2013 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHORS' SEASONAL AND TWO Cyclone Energy (ACE) (92) 165 165 142 30 32% Net Tropical Cyclone Activity (NTC) (103%) 175 175 150 43 42 summarizes tropical cyclone (TC) activity which occurred in the Atlantic basin during 2013 and verifies

  20. Toarcian extreme warmth led to tropical cyclone intensification

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  1. Influence of tropical cyclones on tropospheric ozone: possible implication

    NASA Astrophysics Data System (ADS)

    Das, S. S.; Ratnam, M. V.; Uma, K. N.; Subrahmanyam, K. V.; Girach, I. A.; Patra, A. K.; Aneesh, S.; Suneeth, K. V.; Kumar, K. K.; Kesarkar, A. P.; Sijikumar, S.; Ramkumar, G.

    2015-07-01

    The present study examines the role of tropical cyclones in the enhancement of tropospheric ozone. The most significant and new observation is the increase in the upper tropospheric (10-16 km) ozone by 20-50 ppbv, which has extended down to the middle (6-10 km) and lower troposphere (< 6 km). The descending rate of enhanced ozone layer is found to be 0.87-1 km day-1. Numerical simulation of potential vorticity, vertical velocity and potential temperature indicate the intrusion of ozone from the upper troposphere to the surface. Space borne observations of relative humidity indicate the presence of sporadic dry air in the upper and middle troposphere over the cyclonic region. These observations constitute quantitatively an experimental evidence of enhanced tropospheric ozone during cyclonic storms.

  2. Sensitivity of tropical cyclone Jal simulations to physics parameterizations

    NASA Astrophysics Data System (ADS)

    Chandrasekar, R.; Balaji, C.

    2012-08-01

    In this study, the sensitivity of numerical simulations of tropical cyclones to physics parameterizations is carried out with a view to determine the best set of physics options for prediction of cyclones originating in the north Indian Ocean. For this purpose, the tropical cyclone Jal has been simulated by the advanced (or state of science) mesoscale Weather Research and Forecasting (WRF) model on a desktop mini super computer CRAY CX1 with the available physics parameterizations. The model domain consists of one coarse and two nested domains. The resolution of the coarse domain is 90 km while the two nested domains have resolutions of 30 and 10 km, respectively. The results from the inner most domain have been considered for analyzing and comparing the results. Model simulation fields are compared with corresponding analysis or observation data. The track and intensity of simulated cyclone are compared with best track estimates provided by the Joint Typhoon Warning Centre (JTWC) data. Two sets of experiments are conducted to determine the best combination of physics schemes for track and intensity and it is seen that the best set of physics combination for track is not suitable for intensity prediction and the best combination for track prediction overpredicts the intensity of the cyclone. The sensitivity of the results to orography and level of nesting has also been studied. Simulations were also done for the cyclone Aila with (i) best set of physics and (ii) randomly selected physics schemes. The results of the Aila case show that the best set of physics schemes has more prediction skill than the randomly selected schemes in the case of track prediction. The cumulus (CPS), planetary boundary layer (PBL) and microphysics (MP) parameterization schemes have more impact on the track and intensity prediction skill than the other parameterizations employed in the mesoscale model.

  3. Impact of bogus tropical cyclones on summertime circulation in regional climate simulation

    NASA Astrophysics Data System (ADS)

    Ahn, Young-In; Lee, Dong-Kyou

    2002-08-01

    Ten-year (1987-1996) summertime simulations are conducted using a regional climate model to investigate the impact of tropical cyclones on simulated summertime circulation over east Asia. Toward this end, a tropical cyclone-bogusing scheme is incorporated into a regional climate-modeling framework to realistically describe tropical cyclone structure and its intensity during seasonal integration. The simulated summertime monsoon climatology with and without bogus tropical cyclones incorporated into the large-scale forcing of the NCEP/NCAR reanalysis is analyzed. The model with the bogus tropical cyclones shows improvement in the intensity and tracks of the tropical cyclones. In addition, the well-defined tropical cyclones in the model are sustained for a longer time, so they actually modify the east Asian summer monsoon circulation as well as the extratropical circulation. The bogus tropical cyclones in the model also produce much stronger convection and then a larger amount of precipitation modifying the entire precipitation pattern. Meanwhile, compared with the observations, the intensity of the bogus tropical cyclones weakens more rapidly in the earlier stage of the tropical cyclone development. With the bogus tropical cyclones, the large-scale features over east Asia are closer to observations. Major results are as follows: (1) The intensity of the North Pacific subtropical high becomes weaker, while it is excessively intensified and shifted northward without the bogus tropical cyclones. (2) The southerly or southwesterly monsoon flows in the lower troposphere are reduced, meanwhile they are too strong, accompanying the northward excessive transport of moisture in the no-bogus simulation. (3) The midlatitude jets and storm tracks are intensified and shifted southward. (4) Especially, the retreat of the east Asian summer monsoon in late August is well reproduced, which is completely missed in the cases of poorly resolved tropical cyclones. (5) The empirical orthogonal function analysis reveals that the large-scale variability of the east Asia summertime circulation does appear realistically with the bogus tropical cyclones. (6) The biweekly period related to the life cycle of the intraseasonal monsoon depressions is much weakened, while the period of 5 ~ 7 days associated with the synoptic or mesoscale disturbances, such as tropical cyclone activities, is intensified. One of the important findings in this study is that with the bogus tropical cyclones, the secondary rainy season in late August associated with the retreat of the east Asian summer monsoon is simulated realistically. The secondary rainy season annually takes place in middle-latitude east Asia, especially over southern China, Korea, and Japan. This finding strongly suggests that one of the major reasons for the secondary rainy season could be tropical cyclone activities.

  4. Tropical Cyclone Monty Strikes Western Australia

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

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

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

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

  5. 9.6 NONSUPERCELL TROPICAL CYCLONE TORNADOES: DOCUMENTATION, CLASSIFICATION AND UNCERTAINTIES

    E-print Network

    9.6 NONSUPERCELL TROPICAL CYCLONE TORNADOES: DOCUMENTATION, CLASSIFICATION AND UNCERTAINTIES Roger in the operational prediction of tornado threat, regardless of whether the favorable environment results from midlatitude or tropical perturbations. Since the majority of tropical cyclone (TC) tornadoes are associated

  6. A field theoretical prediction of the tropical cyclone properties

    E-print Network

    Spineanu, Florin

    2013-01-01

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

  7. Monitoring tropical cyclone evolution with NOAA satellite microwave observations

    NASA Technical Reports Server (NTRS)

    Velden, C.; Smith, W. L.

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin

    2015-11-01

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

  10. Tropical Cyclones and Climate Suzana J. Camargo

    E-print Network

    Lance, Veronica P.

    BASIC SCIENCE #12;Self-aggregation: spontaneous organization of convection Applying ideas of self Radiative-Convective Equilibrium What is the role of radiative-convective feedbacks in tropical cyclogenesis of a probabilistic stochastic model #12;Mean absolute error (MAE) of intensity predictions from the persistence (gray

  11. Multi-Scale Aspects of Tropical Cyclone Predictability

    NASA Astrophysics Data System (ADS)

    Doyle, J. D.; Moskaitis, J.; Black, P. G.; Hendricks, E. A.; Reinecke, A.; Amerault, C. M.

    2014-12-01

    The intensification of tropical cyclones (TCs) may be sensitive to aspects of large-scale forcing, as well as internal mesoscale dynamics. In this presentation, the degree to which tropical cyclone intensity and structure is sensitive to small perturbations to the basic properties of the synoptic-scale environment, as well as in the immediate vicinity of the storm, is explored using both adjoint- and ensemble-based approaches. In particular, we explore the relationship between tropical cyclone intensity changes and upper-level outflow. We make use of observations from two recent field campaigns: i) the NASA Hurricane and Severe Storms Sentinel (HS3), which featured two fully instrumented Global Hawk unmanned aerial systems, and ii) the ONR Tropical Cyclone Intensity (TCI-14) experiment that utilized the NASA WB-57. We make use of the Navy's high-resolution tropical cyclone prediction system COAMPS-TC to provide ensemble forecasts, numerical experiments with and without the assimilation of specific observation types (e.g., satellite, dropsondes, high-frequency radiosonde), as well as mesoscale nested adjoint sensitivity and observation impact calculations, all of which provide insight into the initial state sensitivity and predictability issues. We assess the impact of observations in sensitive regions in the TC environment (including outflow regions away from the TC inner core) on predictions of TC intensity and structure. Overall the results underscore the importance of multiple scales that influence the predictability of TC intensification. During HS3, the assimilation of Global Hawk dropsondes has been shown to reduce the maximum wind error from 15 knots to less than 10 knots at 48 h for Hurricane Nadine (2012). In this particular case, the adjoint model shows strong sensitivity in the TC outflow near the entrance region of an upper-level jet. The impact of dropsondes from data denial experiments and adjoint-based observation impact calculations will be discussed for other cases from the HS3 and TCI programs, including Nadine , Leslie (2012), and Gabrielle (2013), as well as other storms such as Superstorm Sandy (2012).

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

    E-print Network

    Webster, Peter J.

    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

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

    E-print Network

    Maryland at College Park, University of

    ABSTRACT Title of Dissertation: THEORETICAL AND NUMERICAL STUDIES OF TROPICAL CYCLONE DEVELOPMENT cyclones (TCs), in which a class of exact solutions is obtained. These solutions capture well many and structures of TCs. In particular, the bottom-upward development of the cyclonic flow is demonstrated

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

    E-print Network

    Li, Tim

    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

  15. Equilibrium Tropical Cyclone Size in an Idealized State of Axisymmetric Radiative–Convective Equilibrium

    E-print Network

    Chavas, Daniel Robert

    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 ...

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

    NASA Video Gallery

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

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

    E-print Network

    Emanuel, Kerry Andrew

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

  18. Storm-centric view of Tropical Cyclone oceanic wakes

    NASA Astrophysics Data System (ADS)

    Gentemann, C. L.; Scott, J. P.; Smith, D.

    2012-12-01

    Tropical cyclones (TCs) have a dramatic impact on the upper ocean. Storm-generated oceanic mixing, high amplitude near-inertial currents, upwelling, and heat fluxes often warm or cool the surface ocean temperatures over large regions near tropical cyclones. These SST anomalies occur to the right (Northern Hemisphere) or left (Southern Hemisphere) of the storm track, varying along and across the storm track. These wide swaths of temperature change have been previously documented by in situ field programs as well as IR and visible satellite data. The amplitude, temporal and spatial variability of these surface temperature anomalies depend primarily upon the storm size, storm intensity, translational velocity, and the underlying ocean conditions. Tropical cyclone 'cold wakes' are usually 2 - 5 °C cooler than pre-storm SSTs, and persist for days to weeks. Since storms that occur in rapid succession typically follow similar paths, the cold wake from one storm can affect development of subsequent storms. Recent studies, on both warm and cold wakes, have mostly focused on small subsets of global storms because of the amount of work it takes to co-locate different data sources to a storm's location. While a number of hurricane/typhoon websites exist that co-locate various datasets to TC locations, none provide 3-dimensional temporal and spatial structure of the ocean-atmosphere necessary to study cold/warm wake development and impact. We are developing a global 3-dimensional storm centric database for TC research. The database we propose will include in situ data, satellite data, and model analyses. Remote Sensing Systems (RSS) has a widely-used storm watch archive which provides the user an interface for visually analyzing collocated NASA Quick Scatterometer (QuikSCAT) winds with GHRSST microwave SSTs and SSM/I, TMI or AMSR-E rain rates for all global tropical cyclones 1999-2009. We will build on this concept of bringing together different data near storm locations when developing the storm-centric database. This database will be made available to researchers via the web display tools previously developed for RSS web pages. The database will provide scientists with a single data format collection of various atmospheric and oceanographic data, and will include all tropical storms since 1998, when the passive MW SSTs from the TMI instrument first became available. Initial results showing an analysis of Typhoon Man-Yi will be presented.

  19. Disaster triggers disaster: Earthquake triggering by tropical cyclones

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Tsukanov, I.

    2011-12-01

    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.

  20. High-Resolution Paleotempestology: Proxy Models for Reconstructing Interannual-Decadal Variations in Pre-Historic Tropical Cyclone Frequency and Intensity

    NASA Astrophysics Data System (ADS)

    Frappier, A. B.; Sahagian, D.; Carpenter, S. J.; Gonz lez, L. A.; Frappier, B. R.

    2005-12-01

    Tropical cyclones (including hurricanes, typhoons, and cyclones) are among the most deadly and destructive natural hazards. As coastal populations and infrastructure in affected areas grow, the impact of these storms is sure to increase. On the other hand, the impact of global climate change on tropical cyclone activity remains uncertain and highly controversial. Recent research suggests that the destructive power of tropical cyclones in the Atlantic and north Pacific has increased substantially in recent decades in response to global warming. Related work also suggests that global tropical cyclone activity may be an important feedback mechanism in the planetary heat transport system that works to stabilize tropical temeratures and de-stabilize polar temperatures. In this century, climate change scenarios project that ocean-atmosphere conditions will become increasingly different from the 20th century for which the best historial and meteorological records of tropical cyclones are available. Geo-biologic proxies for paleotempestology can extend the historical record of tropical cyclone activity, enabling hypothesis testing across a wider array of climate boundary conditions. We present a 23-year tropical stalagmite record of recent stable isotope variations at monthly-weekly temporal resolution contains abrupt low excursions in the stable oxygen isotope ratio (?18O value) of calcite that correspond temporally with recent historical tropical cyclones in the vicinity of the cave. Using logistic regression, we developed a statistical model to detect the proxy signature of tropical cyclone precipitation events in high-resolution speleothem stable isotope records can be used to reconstruct interannual-decadal variations in pre-historic storm frequency. The model reliably identified eight of the ten historically known tropical cyclone proxy signals in this record using the measurable parameters ?18O value, ?13C value, and single point changes in ?18O value; the model incorrectly classified only one of nearly 1200 non-storm sampling points. We also present a preliminary model to reconstruct the intensity of individual storms from the amplitude of ?18O value excursions. High-resolution speleothem stable isotope records thus may prove a useful new source of data in the effort to elucidate the controversial associations between highly variable tropical cyclone activity and the dynamic range of Quaternary climate.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  2. Tropical Cyclone Wind Retrievals from the Advanced Microwave Sounding Unit: Application to Surface Wind Analysis

    E-print Network

    Collett Jr., Jeffrey L.

    Tropical Cyclone Wind Retrievals from the Advanced Microwave Sounding Unit: Application to Surface Wind Analysis KOTARO BESSHO Japan Meteorological Agency/Meteorological Research Institute, Tsukuba City winds at 850 hPa from tropical cyclones retrieved using the nonlinear balance equation, where the mass

  3. SCALAR WIND SPEED AND DIRECTION TROPICAL CYCLONE RETRIEVALS FOR CONICAL SCANNING SCATTEROMETERS

    E-print Network

    Hennon, Christopher C.

    SCALAR WIND SPEED AND DIRECTION TROPICAL CYCLONE RETRIEVALS FOR CONICAL SCANNING SCATTEROMETERS--Scatterometer measurements of ocean vector winds (OVW) are significantly degraded in the presence of the precipitation, especially in tropical cyclones. This paper presents a new ocean hurricane/typhoon wind vector retrieval

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

    E-print Network

    Elsner, James B.

    Do Tropical Cyclones Shape Shorebird Habitat Patterns? Biogeoclimatology of Snowy Plovers. In Florida the Snowy Plover (Charadrius alexandrinus nivosus) is resident along northern and western white impacted relatively more frequently by tropical cyclones. The odds of Snowy Plover nesting in these areas

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

    E-print Network

    Corbosiero, Kristen L.

    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

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

    ERIC Educational Resources Information Center

    Tang, Jiang

    2010-01-01

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

  7. P 3.1 TROPICAL CYCLONE TORNADO RECORDS FOR THE MODERNIZED NWS ERA Roger Edwards1

    E-print Network

    P 3.1 TROPICAL CYCLONE TORNADO RECORDS FOR THE MODERNIZED NWS ERA Roger Edwards1 Storm Prediction and BACKGROUND Tornadoes from tropical cyclones (hereafter TCs) pose a specialized forecast challenge at time, there is a growing realization that some TC tornadoes are not necessarily supercellular in origin (Edwards et al

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

    E-print Network

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

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

    E-print Network

    Nolan, David S.

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

  10. Tropical Cyclone Winds Retrieved from Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Horstmann, Jochen; Wackerman, Chris; Foster, Ralph; Caruso, Michael; Graber, Hans

    2013-04-01

    Within this paper we will introduce and validate our methodologies to retrieve high-resolution wind fields from synthetic aperture radar (SAR) with particular focus on tropical cyclones. SAR wind directions are extracted from the orientation of wind induced streaks, which are visible in the SAR images and that in general are well aligned with the mean surface wind direction. Wind speeds are retrieved from the measured normalized radar cross section (NRCS) from the ocean surface under consideration on the SAR derived wind direction and imaging geometry. Depending on the frequency as well as the SAR polarization for transmit and receive different geophysical model functions (GMF) have to be considered. In case of SAR data acquired at C-band with co-polarization using vertical (V) polarization in transmit and receive we use the well-known C-band model CMOD5n. For horizontal polarization in transmit and receive (HH-polarization) the CMOD5n model is extended by a function that describes the ratio of V to H polarization. For images acquired at H-polarization for transmit and V-polarization for receive (cross pol) or vice versa, we have developed our own GMF. We have investigated a large data set of SAR data acquired under tropical cyclone conditions and compared our retrieved wind fields to scatterometer winds, GPS drope sonde surface wind vectors and SFMR wind speeds acquired during the storms. The results show the quality of the SAR-retrieved wind fields from co-pol and, in particular, cross-pol winds., The later have an rms error similar to the SFMR measurements, which up to date is one of the best accepted wind measurement sources for tropical cyclone winds.

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

    E-print Network

    Chen, Tsing-Chang "Mike"

    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

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

    E-print Network

    Miami, University of

    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

  13. Sensitivity of Tropical Cyclone Intensity to Ventilation in an Axisymmetric Model National Center for Atmospheric Research,* Boulder, Colorado

    E-print Network

    Tang, Brian

    Sensitivity of Tropical Cyclone Intensity to Ventilation in an Axisymmetric Model BRIAN TANG) ABSTRACT The sensitivity of tropical cyclone intensity to ventilation of cooler, drier air into the inner core is examined using an axisymmetric tropical cyclone model with parameterized ventilation

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

    E-print Network

    Connors, Daniel A.

    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

  15. Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

    NASA Astrophysics Data System (ADS)

    Babu, S. Ravindra; Venkat Ratnam, M.; Basha, Ghouse; Krishnamurthy, B. V.; Venkateswara Rao, B.

    2015-05-01

    Tropical cyclones (TCs) are deep convective synoptic scale systems and play an important role in modifying the thermal structure, tropical tropopause parameters and hence stratosphere-troposphere exchange (STE) processes. In the present study, high vertical resolution and high accuracy measurements from COSMIC Global Positioning System (GPS) Radio Occultation (RO) measurements are used to investigate and quantify the effect of tropical cyclones that occurred over Bay of Bengal and Arabian Sea in last decade on the tropical tropopause parameters. The tropopause parameters include cold point tropopause altitude (CPH) and temperature (CPT), lapse rate tropopause altitude (LRH) and temperature (LRT) and the thickness of the tropical tropopause layer (TTL), that is defined as the layer between convective outflow level (COH) and CPH, obtained from GPS RO data. From all the TCs events, we generate the mean cyclone-centered composite structure for the tropopause parameters and removed from climatological mean obtained from averaging the GPS RO data from 2002-2013. Since the TCs include eye, eye walls and deep convective bands, we obtained the tropopause parameters based on radial distance from cyclone eye. In general, decrease in the CPH in the eye is noticed as expected. However, as the distance from cyclone eye increases by 3, 4, and 5° an enhancement in CPH (CPT), LRH (LRT) are observed. Lowering of CPH (0.6 km) and LRH (0.4 km) values with coldest CPT and LRT (2-3 K) within the 500 km radius from the TC centre is noticed. Higher (2 km) COH leading to the lowering of TTL thickness (2-3 km) is clearly observed. There exists multiple tropopause structures in the profiles of temperature obtained within 1° from centre of TC. These changes in the tropopause parameters are expected to influence the water vapour transport from troposphere to lower stratosphere and ozone from lower stratosphere to the upper troposphere and hence STE processes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  18. Recurving western North Pacific tropical cyclones and midlatitude predictability

    NASA Astrophysics Data System (ADS)

    Aiyyer, A.

    2015-09-01

    Data from an ensemble prediction system are used to examine the impact of recurving tropical cyclones on downstream midlatitude forecasts. The ensemble spread, normalized by its climatology, increases after recurvature and peaks approximately 4-5 days later. It returns to climatological levels within a week after recurvature. Initially, the spread increases around the position of the tropical storm. Subsequently, it increases after extratropical transition, and it is associated with a developing wave packet in the midlatitude storm track. The enhanced spread propagates downstream approximately at the group speed of the wave packet. These results suggest that relative to the model's baseline, recurvature-related increase in loss of forecast skill is spatially and temporally localized. Further, energy dispersion of the developing wave packet may constrain the rate at which the forecast errors propagate downstream.

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

    NASA Astrophysics Data System (ADS)

    Kang, Nam-Young; Elsner, James B.

    2015-07-01

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

  20. 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)

    Struchtrup, Henning; Thatcher, Toby

    2007-08-01

    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 Niño 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

    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.

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

    PubMed Central

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

    2015-01-01

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

  5. Mediterranean Tropical-like Cyclones: Present and Future

    NASA Astrophysics Data System (ADS)

    Cavicchia, Leone; von Storch, Hans; Gualdi, Silvio

    2014-05-01

    The Mediterranean basin is characterized by the genesis of a large number of cyclonic systems. Most of the cyclones generated in this area have a baroclinic nature. A few storms every year, however, develop a dynamical evolution similar to the one of tropical cyclones, showing an axis-symmetric vertical profile, a warm core, a cloud-free eye surrounded by a cloud cover with spiral shape, and winds up to the hurricane speed. The strongest between such storms exhibit a striking resemblance to the lower-latitudes hurricanes, except for the mesoscale spatial extent, and have thus been termed medicanes (Mediterranean hurricanes). Medicanes are considered rare phenomena, - the number of observed cases documented in the literature is around ten - but are associated to severe damage on coastal areas. Due to the scarcity of observations over sea, and to the coarse resolution of the long-term reanalysis datasets, it is difficult to construct a homogeneous statistics of the formation of medicanes. Using an approach (tested on a number of historical medicane cases) based on the high-resolution dynamical downscaling of the NCEP/NCAR reanalysis, and exploiting an objective detection algorithm specifically designed to single out the features of medicanes, the statistical properties of such storms (annual cycle, decadal and inter-annual variability, geographical distribution, trends) over the last six decades have been studied in a systematic way, and the linkage between the frequency of medicanes formation and synoptic patterns has been investigated. It was found that medicanes occur indeed with a low frequency, and that they are formed mostly during the cold season in the western Mediterranean and in the region extending between the Ionian Sea and the northern coast of Africa. The analysis of the environmental factors related with the formation of medicanes shows that the genesis mechanism requires a sufficiently large difference between the sea surface temperature and the temperature in the upper atmospheric layers, in order to increase the atmospheric instability. A low wind shear, high moisture content, and high low-level vorticity are all factors that favor the development of medicanes. Applying the same downscaling procedure to the atmospheric fields produced by a global model, forced with the greenhouse gas concentration prescribed in different future climate scenarios, the impact of climate change on the statistics of Mediterranean tropical-like cyclones is estimated. It is found that in the last three decades of the current century, the frequency of mesoscale Mediterranean storms showing tropical-like features is projected to decrease. On the other hand, the percentage of such storms reaching a high intensity shows a tendency towards a moderate increase. References: - Cavicchia L, von Storch H: The simulation of medicanes in a high-resolution regional climate model. Clim. Dyn. 39:2273-2290 (2012) - Cavicchia L, von Storch H, Gualdi S: A long-term climatology of medicanes. Clim. Dyn. DOI: 10.1007/s00382-013-1893-7 (2013) - Cavicchia L, Gualdi S, von Storch H: Mediterranean tropical-like cyclones: present and future, in preparation.

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

    PubMed Central

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

    2011-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2012-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2009-01-01

    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.

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

    E-print Network

    Poh, Chung-Kiak

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    Ten-year moving averages of the seasonal rates for "named storms," tropical storms, hurricanes, and major (or intense) hurricanes in the Atlantic basin 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.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2001-01-01

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

  13. Global Losses and Declining Vulnerability to Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Narita, D.; Hsiang, S. M.

    2011-12-01

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

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

    E-print Network

    Miami, University of

    Cyclones YUMIN MOON, DAVID S. NOLAN, AND MOHAMED ISKANDARANI Rosenstiel School of Marine and Atmospheric 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

  15. ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 6, 2010, 12461258 Changes in the Tropical Cyclone Genesis Potential Index over

    E-print Network

    Drange, Helge

    ) was employed to investigate possible impacts of global warming on tropical cyclone genesis over the western, tropical cyclone, western North Pacific, global warming, SRES A2 Citation: Zhang, Y., H. J. Wang, J. Q. Sun cyclones have caused a marked rise in human and economic dam- age to many coastal areas. Therefore

  16. SUMMARY OF 2010 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHOR'S SEASONAL AND TWO-WEEK FORECASTS

    E-print Network

    Connors, Daniel A.

    SUMMARY OF 2010 ATLANTIC TROPICAL CYCLONE ACTIVITY AND VERIFICATION OF AUTHOR'S SEASONAL AND TWO of Net Tropical Cyclone activity occurs after this date 1 Research Scientist 2 Professor Emeritus.3) 3-5 4 5 5 5 Major Hurricane Days (MHD) (5.0) 6-12 10 13 13 11 Accumulated Cyclone Energy (ACE) (96

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

    PubMed

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

    2011-11-01

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

  18. Avoided Impacts in Ensembles of Tropical Cyclone Damage Potential

    NASA Astrophysics Data System (ADS)

    Done, J.; Paimazumder, D.; Holland, G. J.; Towler, E.

    2014-12-01

    Anthropogenic climate change has the potential to alter current levels of Tropical Cyclone (TC) damage, yet the degree of change and its importance relative to changes in exposure and vulnerability are debated. This study isolates the climate drivers of TC damage and develops an approach to translate climate model data directly to a measure of Cyclone Damage Potential (CDP). The actual damage then depends on a given user's impacted exposure and vulnerability. Our approach is motivated by recent work that highlighted the importance of accounting for TC size and TC translation speed in addition to maximum wind speed in driving TC damage. Since coarse resolution climate models are not able to adequately capture many TC characteristics, these key damaging parameters are modeled in terms of large-scale climate variables, to sidestep the need for information on individual TCs and to enable assessments of CDP directly from large-scale climate model data. The CDP is applied to ensembles of future climates generated under a range of anthropogenic forcing scenarios to assess the degree of avoided CDP under lower emission pathways. Users may then translate avoided CDP to avoided losses using relationships between CDP and their specific exposure and vulnerability characteristics.

  19. Tropical Cyclone Forecasting Applications of the GOES WMSI

    E-print Network

    Pryor, K L

    2006-01-01

    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...

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

    PubMed Central

    Marler, Thomas E; Ferreras, Ulysses

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [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.

  2. Tropical cyclone flow asymmetries induced by a uniform flow revisited

    NASA Astrophysics Data System (ADS)

    Thomsen, Gerald L.; Smith, Roger K.; Montgomery, Michael T.

    2015-09-01

    We investigate the hypothesized effects of a uniform flow on the structural evolution of a tropical cyclone using a simple idealized, three-dimensional, convection-permitting, numerical model. The study addresses three outstanding basic questions concerning the effects of moist convection on the azimuthal flow asymmetries and provides a bridge between the problem of tropical cyclone intensification in a quiescent environment and that in vertical shear over a deep tropospheric layer. At any instant of time, explicit deep convection in the model generates flow asymmetries that tend to mask the induced flow asymmetries predicted by the dry, slab boundary layer model of Shapiro, whose results are frequently invoked as a benchmark for characterizing the boundary layer-induced vertical motion for a translating storm. In sets of ensemble experiments in which the initial low-level moisture field is randomly perturbed, time-averaged ensemble mean fields in the mature stage show a coherent asymmetry in the vertical motion rising into the eyewall and in the total (horizontal) wind speed just above the boundary layer. The maximum ascent occurs about 45° to the left of the vortex motion vector, broadly in support of Shapiro's results, in which it occurs ahead of the storm, and consistent with one earlier more complex numerical calculation by Frank and Ritchie. The total wind asymmetry just above the boundary layer has a maximum in the forward right sector, which is in contrast to the structure effectively prescribed by Shapiro based on an inviscid dry symmetric vortex translating in a uniform flow where, in an Earth-relative frame, the maximum is on the right.

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

    PubMed

    Carrigan, Adam D; Puotinen, Marji

    2014-05-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.

    2012-01-01

    The controversial role of the dry Saharan Air Layer (SAL) on tropical storm intensification in the Atlantic will be addressed. The SAL has been argued in previous studies to have potential positive influences on storm development, but most recent studies have argued for a strong suppressing influence on storm intensification as a result of dry air, high stability, increased vertical wind shear, and microphysical impacts of dust. Here, we focus on observations of Hurricane Helene (2006), which occurred during the NASA African Monsoon Multidisciplinary Activities (NAMMA) experiment. Satellite and airborne observations, combined with global meteorological analyses depict the initial environment of Helene as being dominated by the SAL, although with minimal evidence that the SAL air actually penetrated to the core of the disturbance. Over the next several days, the SAL air quickly moved westward and was gradually replaced by a very dry, dust-free layer associated with subsidence. Despite the wrapping of this very dry air around the storm, Helene intensified steadily to a Category 3 hurricane suggesting that the dry air was unable to significantly slow storm intensification. Several uncertainties remain about the role of the SAL in Helene (and in tropical cyclones in general). To better address these uncertainties, NASA will be conducting a three year airborne campaign called the Hurricane and Severe Storm Sentinel (HS3). The HS3 objectives are: To obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers (that help to isolate tropical disturbances from hostile environments). To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. The mission objectives will be achieved using two Global Hawk (GH) Unmanned Airborne Systems (UASs) with separate comprehensive environmental and over-storm payloads. The GH flight altitudes (>16.8 km) allow overflights of most convection and sampling of upper-tropospheric winds. Deployments from Goddard s Wallops Flight Facility and 26-hour flight durations will provide coverage of the entire Atlantic Ocean basin, and on-station times up to 5-22 h depending on storm location. Deployments will be in September of 2012 and from late-August to late- September 2013-2014, with up to eleven 26-h flights per deployment.

  6. Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Tropical cyclones (TCs) are deep convective synoptic-scale systems that play an important role in modifying the thermal structure, tropical tropopause parameters and hence also modify stratosphere-troposphere exchange (STE) processes. In the present study, high vertical resolution and high accuracy measurements from COSMIC Global Positioning System (GPS) radio occultation (RO) measurements are used to investigate and quantify the effect of tropical cyclones that occurred over Bay of Bengal and Arabian Sea in the last decade on the tropical tropopause parameters. The tropopause parameters include cold-point tropopause altitude (CPH) and temperature (CPT), lapse-rate tropopause altitude (LRH) and temperature (LRT) and the thickness of the tropical tropopause layer (TTL), that is defined as the layer between convective outflow level (COH) and CPH, obtained from GPS RO data. From all the TC events, we generate the mean cyclone-centred composite structure for the tropopause parameters and removed it from the climatological mean obtained from averaging the GPS RO data from 2002 to 2013. Since the TCs include eye, eye walls and deep convective bands, we obtained the tropopause parameters based on radial distance from the cyclone eye. In general, decrease in the CPH in the eye is noticed as expected. However, as the distance from the cyclone eye increases by 300, 400, and 500 km, an enhancement in CPH (CPT) and LRH (LRT) is observed. Lowering of CPH (0.6 km) and LRH (0.4 km) values with coldest CPT and LRT (2-3 K) within a 500 km radius of the TC centre is noticed. Higher (2 km) COH leading to the lowering of TTL thickness (2-3 km) is clearly observed. There are multiple tropopause structures in the profiles of temperature obtained within 100 km from the centre of the TC. These changes in the tropopause parameters are expected to influence the water vapour transport from the troposphere to the lower stratosphere, and ozone from the lower stratosphere to the upper troposphere, hence influencing STE processes.

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

    E-print Network

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. Tropical Cyclone Mahasen Rain Moving Into Bay Of Bengal - Duration: 5 seconds.

    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...

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

    E-print Network

    Klima, Kelly

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

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

    E-print Network

    Moskaitis, Jonathan Robert

    2009-01-01

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

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

    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...

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

    E-print Network

    Zimmerman, Neil L

    2012-01-01

    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 ...

  14. Impact of the latitudinal distribution of tropical cyclones on ocean heat transport

    E-print Network

    Jansen, Malte Friedrich

    The heavy winds associated with tropical cyclones generate strong upper ocean mixing. Recent studies suggest that this enhanced mixing significantly contributes to the ocean poleward heat transport, mainly due to a ...

  15. Cluster Analysis of Downscaled and Explicitly Simulated North Atlantic Tropical Cyclone Tracks

    E-print Network

    Daloz, Anne S.

    A realistic representation of the North Atlantic tropical cyclone tracks is crucial as it allows, for example, explaining potential changes in U.S. landfalling systems. Here, the authors present a tentative study that ...

  16. Long-term rainfall risk from tropical cyclones in coastal areas

    E-print Network

    Veneziano, Daniele

    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 ...

  17. Capture and Characterization of Wind-Driven Rain during Tropical Cyclones and Supercell Thunderstorms

    E-print Network

    rain gauge system on one of tCapture and Characterization of Wind-Driven Rain during Tropical Cyclones and Supercell and the quantification of rain deposition on the building façade. A significant amount or research has been directed

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

    E-print Network

    Langousis, Andreas, 1981-

    2009-01-01

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

  19. NASA GPM Measures Tropical Cyclone 05S (Bohale), Dec. 9 2015 - Duration: 13 seconds.

    NASA Video Gallery

    On Dec. 9, 2015, NASA's Global Precipitation Measurement (GPM) mission measured thunderstorm tops reaching heights on Tropical Cyclone 05S (Bohale) above 16.6 km (10.3 miles) near the center of the...

  20. Are Special Processes at Work in the Rapid Intensification of Tropical Cyclones?

    E-print Network

    Kowch, Roman

    Probably not. Frequency distributions of intensification and dissipation developed from synthetic open-ocean tropical cyclone data show no evidence of significant departures from exponential distributions, though there is ...

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

    E-print Network

    Emanuel, Kerry Andrew

    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 ...

  2. Assessing impact of the sulfate aerosol first indirect effect on tropical cyclone activity

    E-print Network

    Chang, Hao-yu Derek

    2015-01-01

    Tropical cyclones (TCs) are among the most expensive and lethal geophysical hazards. Studies suggest that the intensity of TCs will increase due to the thermodynamic effects of anthropogenic greenhouse gas input. In contrast, ...

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

    E-print Network

    Emanuel, Kerry Andrew

    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 ...

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

    E-print Network

    Kossin, James P.

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

  5. TRMM Sees Rainfall Totals from Tropical Cyclone Guito - Duration: 6 seconds.

    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...

  6. Tropical Cyclone Data Assimilation: Experiments with a Coupled Global-Limited-Area Analysis System 

    E-print Network

    Holt, Christina

    2014-04-22

    This study investigates the benefits of employing a limited-area data assimilation (DA) system to enhance lower-resolution global analyses in the Northwest Pacific tropical cyclone (TC) basin. Numerical experiments are carried out with a global...

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

    E-print Network

    Woodruff, Jonathan Dalrymple

    2009-01-01

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

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

    SciTech Connect

    Rodgers, E.B.

    1992-01-01

    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.

  9. Interdecadal variation of Korea affecting tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  10. Tropical Cyclones Feed More Heavy Rain in a Warmer Climate

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  11. Beyond Hurricane Sandy: What Might the Future Hold for Tropical Cyclones in the North Atlantic?

    NASA Technical Reports Server (NTRS)

    Horton, Radley M.; Liu, Jiping

    2014-01-01

    Coastal communities are beginning to understand that sea level rise is projected to dramatically increase the frequency of coastal flooding. However, deep uncertainty remains about how tropical cyclones may change in the future. The North Atlantic has historically been responsible for the majority of global tropical cyclone economic losses, with Hurricane Sandy's approximately USD $70 billion price tag providing a recent example. The North Atlantic has experienced an upward trend in both total tropical cyclones (maximum sustained winds greater than18 m/s) and major hurricanes (maximum sustained winds greater than 50 m/s) in recent decades. While it remains unclear how much of this trend is related to anthropogenic warming, and how tropical cyclone risk may change in the future, the balance of evidence suggests that the strongest hurricanes may become more frequent and intense in the future, and that rainfall associated with tropical cyclones may increase as well. These projections, along with sea level rise and demographic trends, suggest vulnerability to tropical cyclones will increase in the future, thus requiring major coastal adaptation initiatives.

  12. Energy flow in a high-resolution 3D tropical cyclone simulation

    NASA Astrophysics Data System (ADS)

    O'Neill, M. E.; Emanuel, K.

    2011-12-01

    Mature tropical cyclones have been realistically simulated by both axisymmetric models and three-dimensional models. However, observed tropical cyclones have significant asymmetries in the form of rain bands and vortical hot towers (VHTs). The role of asymmetries in rapid intensification of a nascent tropical cyclone remains unknown. Recent work has implicated VHTs as the preferred source of PV anomalies in a strengthening tropical cyclone; however, further studies dispute this hypothesis as a driver for rapid intensification. In this work we explore the Lorenz energy cycle in a 3-D tropical cyclone simulation. Using a 2 km resolution anelastic equation model, the mean flow and eddy energy conversions between available potential energy (APE) and kinetic energy (KE) are compared over the storm's lifetime. The motivation is to determine whether eddy-driven up-gradient energy flow is a dominant means of strengthening a simulated tropical cyclone. Results indicate that, in a simulation with no background shear, asymmetries in fact draw energy from the storm; eddy KE is primarily powered by mean KE, weakening the mean flow. This is consistent with the results of Kwon and Frank (2008). The effect of adding shear to the model will also be examined.

  13. Multi-model GCM ensemble simulations of idealized tropical cyclones

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Misra, Vasubandhu; Bastola, Satish

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  16. Extratropical Transition Using 23 Years of Tropical Cyclones in a Variable-Resolution Global GCM

    NASA Astrophysics Data System (ADS)

    Thatcher, D. R.; Zarzycki, C. M.; Ferguson, J. O.; Jablonowski, C.

    2014-12-01

    The impact of increased resolution on extratropical transition of tropical cyclones is analyzed using the Community Atmosphere Model version 5 (CAM5) with the variable-resolution Spectral Element (SE) dynamical core. Over the North Atlantic tropics, a high-resolution 28 km grid spacing allows the model to sufficiently resolve the structure of tropical cyclones, including sharp gradients in the eye wall. As the tropical cyclone travels beyond the high-resolution nest, the grid spacing transitions to 110 km. This approach is computationally efficient, while the resolution is high enough for the study of the extratropical transition of cyclones in the Atlantic Ocean. We compare 23-year simulations with prescribed sea surface temperatures and sea ice according to the Atmospheric Model Intercomparison Project (AMIP) protocol using both the variable-resolution 28-110 km grid and a uniform-mesh 110 km simulation. In particular, we evaluate the climatology of extratropical transition throughout the simulations and compare to reanalysis data. Phase space analysis follows the structural evolution of storms as they transition from symmetric, warm-core tropical cyclones to asymmetric, cold-core extratropical storms. The precipitation rate and the distribution about the storm change throughout the storms' lifecycles. An individual analysis of selected storms demonstrates the development of cyclone asymmetries, a cold-core structure, and precipitation extremes as the storm undergoes extratropical transition.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  18. Aerosols-Cloud-Microphysics Interactions in Tropical Cyclone Earl

    NASA Astrophysics Data System (ADS)

    Luna-Cruz, Yaitza

    Aerosols-cloud-microphysical processes are largely unknown in their influence on tropical cyclone evolution and intensification; aerosols possess the largest uncertainty. For example: What is the link between aerosols and cloud microphysics quantities? How efficient are the aerosols (i.e. dust from the Saharan Air Layer -SAL) as cloud condensation nuclei (CCN) and ice nuclei (IN)? Does aerosols affect the vertical velocity, precipitation rates, cloud structure and lifetime? What are the dominant factors and in which sectors of the tropical cyclone? To address some of the questions in-situ microphysics measurements from the NASA DC-8 aircraft were obtained during the Genesis and Rapid Intensification Processes (GRIP) 2010 field campaign. A total of four named storms (Earl, Gaston, Karl and Mathew) were sampled. Earl presented the excellent opportunity to study aerosols-cloud-microphysics interactions because Saharan dust was present and it underwent rapid intensification. This thesis seeks to explore hurricane Earl to develop a better understanding of the relationship between the SAL aerosols and cloud microphysics evolution. To assist in the interpretation of the microphysics observations, high resolution numerical simulations of hurricane Earl were performed using the Weather Research and Forecasting (WRF-ARW) model with the new Aerosol-Aware bulk microphysics scheme. This new version of Thompson scheme includes explicit activation of cloud condensation nuclei (CCN) from a major CCN source (i.e. sulfates and sea salt) and explicit ice nucleation (IN) from mineral dust. Three simulations are performed: (1) the Control case with the old Thompson scheme and initial conditions from GFS model, (2) the Aerosol-Aware first baseline case with GOCART aerosol module as an input conditions, and (3) the Aerosol-Aware increase case in which the GOCART aerosols concentrations were increased significantly. Overall, results of model simulations along with aircraft observations reveal that the injection of dust; reduce relative humidity values producing a dryer ambient air, increase the hydrometeor concentration (cloud/rain droplets, snow and ice), reduce the size of the hydrometeor (cloud droplets, snow and ice), increased outer rain number concentration producing a larger storm, and has a minimal effect on track but a high impact on the intensity forecast except during rapid intensification.

  19. Ensemble forecasting of tropical cyclone motion using a baroclinic model

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaqiong; Chen, Johnny C. L.

    2006-05-01

    The purpose of this study is to investigate the effectiveness of two different ensemble forecasting (EF) techniques-the lagged-averaged forecast (LAF) and the breeding of growing modes (BGM). In the BGM experiments, the vortex and the environment are perturbed separately (named BGMV and BGME). Tropical cyclone (TC) motions in two difficult situations are studied: a large vortex interacting with its environment, and an apparent binary interaction. The former is Typhoon Yancy and the latter involves Typhoon Ed and super Typhoon Flo, all occurring during the Tropical Cyclone Motion Experiment TCM-90. The model used is the baroclinic model of the University of New South Wales. The lateral boundary tendencies are computed from atmospheric analysis data. Only the relative skill of the ensemble forecast mean over the control run is used to evaluate the effectiveness of the EF methods, although the EF technique is also used to quantify forecast uncertainty in some studies. In the case of Yancy, the ensemble mean forecasts of each of the three methodologies are better than that of the control, with LAF being the best. The mean track of the LAF is close to the best track, and it predicts landfall over Taiwan. The improvements in LAF and the full BGM where both the environment and vortex are perturbed suggest the importance of combining the perturbation of the vortex and environment when the interaction between the two is appreciable. In the binary interaction case of Ed and Flo, the forecasts of Ed appear to be insensitive to perturbations of the environment and/or the vortex, which apparently results from erroneous forecasts by the model of the interaction between the subtropical ridge and Ed, as well as from the interaction between the two typhoons, thus reducing the effectiveness of the EF technique. This conclusion is reached through sensitivity experiments on the domain of the model and by adding or eliminating certain features in the model atmosphere. Nevertheless, the forecast tracks in some of the cases are improved over that of the control. On the other hand, the EF technique has little impact on the forecasts of Flo because the control forecast is already very close to the best track. The study provides a basis for the future development of the EF technique. The limitations of this study are also addressed. For example, the above results are based on a small sample, and the study is actually a simulation, which is different than operational forecasting. Further tests of these EF techniques are proposed.

  20. A reassessment of the integrated impact of tropical cyclones on surface chlorophyll in the western subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical North Atlantic Ocean during 1998-2011. Previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone-induced mixing for changes in surface chlorophyll. Using a more integrated and comprehensive approach that includes quantification of cyclone-induced changes in mixed layer depth, here it is shown that accumulated cyclone energy explains 22% of the interannual variability in seasonally averaged (June-November) chlorophyll concentration in the western subtropical North Atlantic, after removing the influence of the North Atlantic Oscillation (NAO). The variance explained by tropical cyclones is thus about 70% of that explained by the NAO, which has well-known impacts in this region. It is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical North Atlantic during the hurricane season.

  1. A Reassessment of the Integrated Impact of Tropical Cyclones on Surface Chlorophyll in the Western Subtropical North Atlantic

    SciTech Connect

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

    2015-02-28

    The impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical North Atlantic Ocean during 1998–2011. Previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone-induced mixing for changes in surface chlorophyll. Using a more integrated and comprehensive approach that includes quantification of cyclone-induced changes in mixed layer depth, here it is shown that accumulated cyclone energy explains 22% of the interannual variability in seasonally-averaged (June–November) chlorophyll concentration in the western subtropical North Atlantic, after removing the influence of the North Atlantic Oscillation (NAO). The variance explained by tropical cyclones is thus about 70% of that explained by the NAO, which has well-known impacts in this region. It is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical North Atlantic during the hurricane season.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  3. Tracking Scheme Dependence of Simulated Tropical Cyclone Response to Idealized Climate Simulations

    NASA Technical Reports Server (NTRS)

    Horn, Michael; Walsh, Kevin; Zhao, Ming; Camargo, Suzana J.; Scoccimarro, Enrico (Compiler); Murakami, Hiroyuki; Wang, Hui; Ballinger, Andrew; Kumar, Arun; Shaevitz, Daniel A.; Jonas, Jeffrey A. (Compiler); Oouchi, Kazuyoshi

    2014-01-01

    Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. The influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments is examined herein. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea surface temperature and other increased CO2 effects on tropical cyclone activity. Two tracking schemes are applied to these data and the tracks provided by each modeling group are analyzed. The results herein indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, it is found that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenization in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. The results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.

  4. A review of ensemble forecasting techniques with a focus on tropical cyclone forecasting

    NASA Astrophysics Data System (ADS)

    Cheung, Kevin K. W.

    2001-09-01

    This paper presents a general review of ensemble forecasting techniques, with a focus on short-range and tropical cyclone predictions. The basic ideas and terminology of ensemble forecasting are introduced, and using four measures to evaluate an ensemble (ensemble mean forecast, consistency, spread versus skill, and inclusiveness), various potential utilities (e.g. dynamical probabilistic forecasts) are illustrated. Since the perturbation methodologies designed for medium-range forecasts of mid-latitude synoptic-scale systems - singular vectors, bred modes, and so on - are already quite mature, they are only briefly described here. The general problems encountered in applying ensemble forecasting techniques to short-range and tropical cyclone forecasts are diagnosed, and some recent studies on these topics reviewed. In general, the perturbation methodologies used for short-range ensembles to date can have a skill comparable to or slightly higher than their corresponding high-resolution control forecast. However, the complicated problem of the relationship between initial condition errors and model deficiencies persists. A similar situation also applies to ensembles designed for tropical cyclone forecasting. An additional difficulty is the different error characteristics encountered in the tropics, mainly the result of the strong convection in the area and the mutual interaction with the ocean. Studies from several research groups use quite different perturbation methodologies, but the results are encouraging. Most of them performed ensemble forecasting of tropical cyclone motion, but extensions to tropical cyclone intensity forecasts are also being developed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  6. Modeling Tropical Cyclones in NCAR's General Circulation Model with Variable-Resolution Meshes

    NASA Astrophysics Data System (ADS)

    Zarzycki, C. M.; Jablonowski, C.

    2011-12-01

    Modeling of tropical cyclones in General Circulation Models (GCMs) has historically been a difficult task due to small storm size and intense convective processes which require significant parameterization. At traditional GCM grid resolutions of 50-200 km, tropical cyclones are significantly under-resolved, if not completely unresolved. However, recent advances in both computing technology and GCM model design now allow for GCMs with grid spacings as small as 15-30 km. At these resolutions, models are able to capture the key processes of tropical cyclones more reliably. This paper evaluates the inherent potential of GCMs at very high horizontal resolutions to simulate tropical cyclones. In particular, we explore a novel variable-resolution mesh approach that allows for high spatial resolutions in areas of interest, such as low-latitude ocean basins where tropical cyclones are prevalent. Such GCM designs with variable-resolution meshes have the potential to become the future tool for regional climate assessments. A statically-nested, variable-mesh option has recently been introduced into the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). In particular, the variable-mesh option is now supported in the forthcoming Spectral Element (SE) dynamical core that is scheduled to become the NCAR default in CAM version 5.2. The SE dynamical core is also known as the 'High-Order Method Modeling Environment' (HOMME). We present preliminary CAM-SE model simulations using an idealized tropical cyclone in an aqua-planet configuration. The initial warm-core vortex is axisymmetric and in hydrostatic and gradient-wind balance. We test the model's ability to intensify and maintain these tropical cyclones with a variety of grid sizes and refinement scales. The analysis pays special attention to storm formation and subsequent motion through the fine-coarse-grid transition regions, as well as to changes in storm dynamical structure as a result of the variable grid sizing.

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

    PubMed

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

    2014-05-15

    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

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

    E-print Network

    Pu, Zhaoxia

    The Influence of Airborne Doppler Radar Data Quality on Numerical Simulations of a Tropical Cyclone The impact of airborne Doppler radar data assimilation on improving numerical simulations of tropical cy of the radar data quality control on assimilation of the airborne Doppler radar reflectivity and radial

  9. Tropical cyclone bebe creates a new land formation on funafuti atoll.

    PubMed

    Maragos, J E; Baines, G B; Beveridge, P J

    1973-09-21

    A huge rubble rampart 18 kilometers long was formed at Funafuti Atoll during tropical cyclone Bebe on 21 October 1972. The material forming the rampart was derived from deeper water offshore. The formation appears to be permanent and indicates that tropical storms may play a significant role in the formation of atoll islets. PMID:17744290

  10. Impact of Stochastic Convection on Ensemble Forecasts of Tropical Cyclone Development

    E-print Network

    Pu, Zhaoxia

    regarding their performance in predicting the development and evolution of tropical cyclones. Forecasts%, but the number of ``false alarms'' for two non- developing systems also increases. However, the increase in false of the genesis and evolution of tropical cy- clones (TCs) remain a great challenge for numerical weather

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  12. Sensitivity of tropical cyclone intensification to inner-core structure

    NASA Astrophysics Data System (ADS)

    Ge, Xuyang; Xu, Wei; Zhou, Shunwu

    2015-10-01

    In this study, the dependence of tropical cyclone (TC) development on the inner-core structure of the parent vortex is examined using a pair of idealized numerical simulations. It is found that the radial profile of inner-core relative vorticity may have a great impact on its subsequent development. For a system with a larger inner-core relative vorticity/inertial stability, the conversion ratio of the diabatic heating to kinetic energy is greater. Furthermore, the behavior of the convective vorticity eddies is likely modulated by the system-scale circulation. For a parent vortex with a relatively higher inner-core vorticity and larger negative radial vorticity gradient, convective eddy formation and radially inward propagation is promoted through vorticity segregation. This provides a greater potential for these small-scale convective cells to self-organize into a mesoscale inner-core structure in the TC. In turn, convectively induced diabatic heating that is close to the center, along with higher inertial stability, efficiently enhances system-scale secondary circulation. This study provides a solid basis for further research into how the initial structure of a TC influences storm dynamics and thermodynamics.

  13. A satellite stereoscopic technique to estimate tropical cyclone intensity

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    The techniques used to obtain the mean equivalent temperature of the eye wall for Hurricanes Frederic (1979) and Allen (1980) using GOES satellite IR and stereoscopic observations are described. The eye wall is the area of greatest convection near the center of the storm, and is bounded by the inner radius around the eye and the outer radius bounding the area of inner core convection. The stereoscopic capability afforded by the GOES West and East spacecraft permits simultaneous, two-view imagery of a tropical cyclone, yielding height measurement accuracies of 0.5 km and horizontal accuracies as small as 1 km. An airborne lidar unit was used to verify the height measurements made of Hurricane Frederic. At the same time, the GOES East Visible IR Spin Scan Radiometer (VISSR) provided the mean wall temperatures from the release of latent heat. The trials aided in identifying the assumptions and consequent inaccuracies introduced into the temperature sounding data during analysis. The satellite data is concluded useful for monitoring changes in storm intensity.

  14. Impact of environmental moisture on tropical cyclone intensification

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  15. Axisymmetrically Tropical Cyclone-like Vortices with Secondary Circulations

    E-print Network

    Sun, Liang

    2013-01-01

    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...

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

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Xu, Xiaolin; Chen, Baode

    2014-05-01

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

  17. Statistical models of tropical cyclone intensity for risk assessment

    NASA Astrophysics Data System (ADS)

    Yonekura, E.; Lin, N.; Xue, L.; Wang, Y.; Fan, J.

    2013-12-01

    New statistical models for tropical cyclone (TC) intensity evolving with the environment are constructed and evaluated. The data used to construct the models comes from the IBTrACS WMO archive for TC-specific data and ERSST version 3b and the NCEP-NCAR Reanalysis for environmental conditions from 1970-2010 in the North Atlantic. The initial model, using linear regression, is based on the operational SHIPS and STIPS models for the North Atlantic and western North Pacific, respectively. The next model uses advanced statistical techniques to select the most important variables and determine non-linear relationships. The last set of models uses a minimum number of predictors including the environmental ventilation index and storm persistence to predict changes in normalized intensity. In all models, the two major intensity indicators, the maximum sustained wind and minimum central pressure, are modeled jointly. The models are compared and a bootstrapping technique is used to evaluate the model skill. Improvements upon previous work include incorporating environmental predictors such that changes in TC activity can be modeled given input from different climates, modeling wind and pressure together without using a fixed empirical conversion, and using the ventilation index as a predictor for intensity. These models may be incorporated into statistical TC track models for risk assessments under climate change.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  19. Dynamics of the Stratiform Sector of a Tropical Cyclone Rainband

    NASA Astrophysics Data System (ADS)

    Didlake, A. C.; Houze, R.

    2013-12-01

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

  20. Forecasting tropical cyclone recurvature with upper tropospheric winds

    NASA Technical Reports Server (NTRS)

    Gentry, R. C.

    1983-01-01

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

  1. Analysis of gravity-waves produced by intense tropical cyclones

    NASA Astrophysics Data System (ADS)

    Chane Ming, F.; Chen, Z.; Roux, F.

    2010-02-01

    Conventional and wavelet methods are combined to characterize gravity-waves (GWs) produced by two intense tropical cyclones (TCs) in the upper troposphere and lower stratosphere (UT/LS) from GPS winsonde data. Analyses reveal large contribution of GWs induced by TCs to wave energy densities in the UT/LS. An increase in total energy density of about 30% of the climatological energy density in austral summer was estimated in the LS above Tromelin during TC Dina. Four distinct periods in GW activity in relation with TC Faxai stages is observed in the UT. Globally, GWs have periods of 6 h-2.5 days, vertical wavelenghts of 1-3 km and horizontal wavelengths <1000 km in the UT during the evolution of TCs. Horizontal wavelengths are longer in the LS and about 2200 km during TCs. Convective activity over the basin and GW energy density were modulated by mixed equatorial waves of 3-4 days, 6-8 days and 10-13 days confirmed by Hövmöller diagram, Fourier and wavelet analyses of OLR data. Moreover, location of GW sources is below the tropopause height when TCs are intense otherwise varies at lower tropospheric heights depending on the strength of convection. Finally, the maximum surface wind speeds of TCs Dina and Faxai can be linearly estimated with total energy densities.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  3. Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: a case study on cyclone Davina (1999)

    NASA Astrophysics Data System (ADS)

    Cairo, F.; Buontempo, C.; MacKenzie, A. R.; Schiller, C.; Volk, C. M.; Adriani, A.; Mitev, V.; Matthey, R.; di Donfrancesco, G.; Oulanovsky, A.; Ravegnani, F.; Yushkov, V.; Snels, M.; Cagnazzo, C.; Stefanutti, L.

    2008-07-01

    During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame. Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400 430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics.

  4. Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: A case study on cyclone Davina (1999)

    NASA Astrophysics Data System (ADS)

    Cairo, F.; Buontempo, C.; MacKenzie, A. R.; Schiller, C.; Volk, C. M.; Adriani, A.; Mitev, V.; Matthey, R.; di Donfrancesco, G.; Oulanovsky, A.; Ravegnani, F.; Yushkov, V.; Snels, M.; Cagnazzo, C.; Stefanutti, L.

    2007-12-01

    During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame. Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone and the perturbed water distribution in the TTL is illustrated and discussed.

  5. Assessing Impacts of Global Warming on Tropical Cyclone Tracks

    NASA Technical Reports Server (NTRS)

    Wu, Li-Guang; Wang, Bin

    2003-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  7. On the response to tropical cyclones in mesoscale oceanic eddies

    NASA Astrophysics Data System (ADS)

    Jaimes, Benjamin

    Tropical cyclones (TCs) often change intensity as they move over mesoscale oceanic features, as a function of the oceanic mixed layer (OML) thermal response (cooling) to the storm's wind stress. For example, observational evidence indicates that TCs in the Gulf of Mexico rapidly weaken over cyclonic cold core eddies (CCEs) where the cooling response is enhanced, and they rapidly intensify over anticyclonic warm features such as the Loop Current (LC) and Warm Core Eddies (WCEs) where OML cooling is reduced. Understanding this contrasting thermal response has important implications for oceanic feedback to TCs' intensity in forecasting models. Based on numerical experimentation and data acquired during hurricanes Katrina and Rita, this dissertation delineates the contrasting velocity and thermal response to TCs in mesoscale oceanic eddies. Observational evidence and model results indicate that, during the forced stage, the wind-driven horizontal current divergence under the storm's eye is affected by the underlying geostrophic circulation. Upwelling (downwelling) regimes develop when the wind stress vector is with (against) the geostrophic OML velocity vector. During the relaxation stage, background geostrophic circulations modulate vertical dispersion of OML near-inertial energy. The near-inertial velocity response is subsequently shifted toward more sub-inertial frequencies inside WCEs, where rapid vertical dispersion prevents accumulation of kinetic energy in the OML that reduces vertical shears and layer cooling. By contrast, near-inertial oscillations are vertically trapped in OMLs inside CCEs that increases vertical shears and entrainment. Estimates of downward vertical radiation of near-inertial wave energies were significantly stronger in the LC bulge (12.1x10-2 W m-2) compared to that in CCEs (1.8x10-2 W m-2). The rotational and translation properties of the geostrophic eddies have an important impact on the internal wave wake produced by TCs. More near-inertial kinetic energy is horizontally trapped in more rapidly rotating eddies. This response enhances vertical shear development and mixing. Moreover, the upper ocean temperature anomaly and near-inertial oscillations induced by TCs are transported by the westward-propagating geostrophic eddies. From a broader perspective, coupled models must capture oceanic features to reproduce the differentiated TC-induced OML cooling to improve intensity forecasting.

  8. Factors That Influence the Size of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. Coal pond fines cleaning with classifying cyclones, spirals, and column flotation

    SciTech Connect

    Carson, W.R.; Arnold, B.J.; Raleigh, C.E. Jr.; Parekh, B.K.

    1997-07-01

    Large reserves of coal pond fines arc found in the Illinois Basin--over 40 million tons in Western Kentucky, over 65 million tons in Southern Illinois, and over 35 million tons in Southern Indiana. If these fines are used to produce coal-water slurry (CWS), fuel costs, NO{sub x} emissions, and pond closure costs can be reduced. Coal fines from this region that are used to produce CWS for co-fire or re-burn may require processing, however, to attain proper particle size distribution and fuel quality. To evaluate the effectiveness of using coal cleaning technologies to control these CWS quality parameters, a simple flowsheet for recovering and processing coal pond fines was designed and tested. Coal fines processing consisted of using classifying cyclones to size at nominal minus 200 mesh, cleaning the classifying cyclone underflow using spirals, and cleaning the overflow using column froth flotation. Ash content of the dean coal from the spiral was reduced to about 10 percent, winch is satisfactory to use for CWS co-firing in a cyclone-fired boiler. The clean coal from column flotation may be used for re-burn in a cydone-fired boiler or as co-fire fuel in a wall-fired or tangentially-fired boiler Heating value recovery during laboratory scale, pilot-scale, and commercial-scale coal cleaning testing was about 80 percent.

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

    E-print Network

    Emanuel, Kerry Andrew

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

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

    NASA Technical Reports Server (NTRS)

    Ritchie, Elizabeth A.

    2003-01-01

    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.

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

    PubMed

    Emanuel, Kerry A

    2013-07-23

    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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Dunion, J.

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  16. Development of a tropical cyclone tracker and applications to tropical cyclones occurred in 2008 in North Western Pacific

    NASA Astrophysics Data System (ADS)

    Kim, J.; Kim, H.; Atmospheirc Predictability; Data Assimilation Laboratory

    2010-12-01

    To investigate whether tropical cyclones (TCs) are simulated correctly and verify forecast skill for TCs in numerical weather prediction models, it is necessary to derive trajectories of TCs from model output data and compare them with TC best track information. Because TC tracks are not model output variables, they can be diagnosed from basic variables as pressure, wind, and temperature of a model. A method to decide the TC center is to find out the center manually by looking at the weather charts. However, this manual method is not efficient and sometimes impossible to pinpoint the TC center. Furthermore, determining TC center manually from ensemble prediction results becomes increasingly inefficient. Thus an objective analysis of TC center and trajectory becomes an indispensable work. In this study, a TC tracker that has been developed (hereafter YSU TC tracker) for various model output format including netCDF used in WRF, binary data used in MM5, and GRIB used in GFS and ECMWF YOTC, with various projection including Lambert conformal and cylindrical equidistant (lat/lon) grid is applied for the model output to investigate the performance of the tracker. In detecting step, YSU TC tracker used mean sea level pressure, vorticity and geopotential height at 700 and 850hPa. In tracking step, a search area of next forecast time is determined with specified radius around TC center position of the next forecast time, guessed by using thresholds of cyclone movement such as direction, range of angle, and search radius based on TC speed between two consecutive analyses. The YSU TC tracker developed above was applied on the TCs occurred in 2008 in North Western Pacific. As a forecast data, 0.5° by 0.5° resolution NCEP GFS and ECMWF YOTC data on cylindrical equidistant grid were used. To investigate the performance of the YSU TC tracker, the YSU TC tracker was applied to the GFS data and the results are compared with those from the NCEP tracker. Average track positional errors from the best track data were similar for both trackers, implying that the YSU TC tracker performs as well as the NCEP tracker. To investigate the average forecast skill of the NCEP GFS and ECMWF YOTC data, the YSU TC tracker was applied on both data. The average track positional errors for both data were similar at the initial time, but the average track positional error of the NCEP GFS becomes larger than that of ECMWF YOTC data as the forecast time increases. More comprehensive results will be presented in the meeting.

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

    E-print Network

    Wang, Yuqing

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

  18. A western North Pacific tropical cyclone intensity prediction scheme

    NASA Astrophysics Data System (ADS)

    Chen, Peiyan; Yu, Hui; Chan, Johnny C. L.

    2011-10-01

    A western North Pacific tropical cyclone (TC) intensity prediction scheme (WIPS) is developed based on TC samples from 1996 to 2002 using the stepwise regression technique, with the western North Pacific divided into three sub-regions: the region near the coast of East China (ECR), the South China Sea region (SCR), and the far oceanic region (FOR). Only the TCs with maximum sustained surface wind speed greater than 17.2 m s-1 are used in the scheme. Potential predictors include the climatology and persistence factors, synoptic environmental conditions, potential intensity of a TC and proximity of a TC to land. Variances explained by the selected predictors suggest that the potential intensity of a TC and the proximity of a TC to land are significant in almost all the forecast equations. Other important predictors include vertical wind shear in ECR, 500-hPa geopotential height anomaly at the TC center, zonal component of TC translation speed in SCR, intensity change of TC 12 or 24 h prior to initial time, and the longitude of TC center in FOR. Independent tests are carried out for TCs in 4 yr (2004-2007), with mean absolute errors of the maximum surface wind being 3.0, 5.0, 6.5, 7.3, 7.6, and 7.9 m s-1 for 12- to 72-h predictions at 12-h intervals, respectively. Positive skills are obtained at all leading time levels as compared to the climatology and persistence prediction scheme, and the large skill scores (near or over 20%) after 36 h imply that WIPS performs especially better at longer leading times. Furthermore, it is found that the amendment in TC track prediction and real-time model analysis can significantly improve the performance of WIPS in the SCR and ECR. Future improvements will focus on applying the scheme for weakening TCs and those near the coastal regions.

  19. Have Tropical Cyclones Been Feeding More Extreme Rainfall?

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

  20. Have Tropical Cyclones been Feeding More Extreme Rainfall?

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. The impact of tropical cyclones (TC) on global climate is still debated. They rapidly mix the water column beneath them, bringing cold water to the surface.

    E-print Network

    Jones, Peter JS

    The impact of tropical cyclones (TC) on global climate is still debated. They rapidly mix the water), and therefore altered tropical cyclone distributions (Fedorov, 2010). Could this have had climate consequences Pliocene, Science , 323, 1714 Fedorov et al., 2010. Tropical cyclones, and permanent El Niño in the Early

  3. 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

    Rhode Island, University of

    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

  4. 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

    Long, David G.

    , 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

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

    E-print Network

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

  6. 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

    Hawai'i at Manoa, University of

    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

  7. Evidence for the significant role of sea surface temperature distributions over remote tropical oceans in tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Hegde, Anitha Kumari; Kawamura, Ryuichi; Kawano, Tetsuya

    2015-10-01

    The role of remote ocean sea surface temperature (SST) in regulating tropical cyclone (TC) characteristics has been examined by performing numerical experiments with a regional scale model. Model simulations have been carried out to simulate typhoon Man-yi (July 2007), in our case study, under a range of SST conditions over the Indian Ocean and the South China Sea. The intensity and track of the cyclone have been systematically changed in sensitivity simulations of cool and warm SSTs over that region, following its peak phase. Warm oceans can substantially reduce the intensification of western North Pacific cyclones, whereas cool oceans can enhance their strength. This is intimately associated with the enhancement/weakening of the moisture supply through the moisture conveyor belt (MCB) in the lower troposphere, from the Indian Ocean and South China Sea into the vicinity of the cyclone center. When the MCB is interrupted over the South China Sea in warm SST occurrences, the large-scale transport of moisture into the cyclone system is significantly reduced, leading to the weakening of the cyclone intensity and to the eastward shift of its track. This study shows that changes in remote tropical ocean SST can also modulate TCs and thus can help in improving the forecasting of TC intensities and tracks.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2014-01-01

    Officially, the North Atlantic basin tropical cyclone season runs from June 1 through November 30 of each year. During this 183-day interval, the vast majority of tropical cyclone onsets are found to occur. For example, in a study of the 715 tropical cyclones that occurred in the North Atlantic basin during the interval 1945-2010, it was found that about 97 percent of them had their onsets during the conventional hurricane season, with the bulk (78 percent) having had onset during the late summer-early fall months of August, September, and October and with none having had onset in the month of March. For the 2014 hurricane season, it already has had the onset of its first named storm on July 1 (day of year (DOY) 182), Arthur, which formed off the east coast of Florida, rapidly growing into a category-2 hurricane with peak 1-minute sustained wind speed of about 90 kt and striking the coast of North Carolina as a category-2 hurricane on July 3. Arthur is the first hurricane larger than category-1 to strike the United States (U.S.) since the year 2008 when Ike struck Texas as a category-2 hurricane and there has not been a major hurricane (category-3 or larger) to strike the U.S. since Wilma struck Florida as a category-3 hurricane in 2005. Only two category-1 hurricanes struck the U.S. in the year 2012 (Isaac and Sandy, striking Louisiana and New York, respectively) and there were no U.S. land-falling hurricanes in 2013 (also true for the years 1962, 1973, 1978, 1981, 1982, 1990, 1994, 2000, 2001, 2006, 2009, and 2010). In recent years it has been argued that the length of season (LOS), determined as the inclusive elapsed time between the first storm day (FSD) and the last storm day (LSD) of the yearly hurricane season (i.e., when peak 1-minute sustained wind speed of at least 34 kt occurred and the tropical cyclone was not classified as 'extratropical'), has increased in length with the lengthening believed to be due to the FSD occurring sooner and the LSD occurring later and with both being related to global warming. In this study, the relationship between the LOS and tropical cyclone activity and climate is examined for the weather satellite era, 1960-2013. Estimates are also given for the LOS and LSD, as well as for the expected number of tropical cyclones (NTC), the total number of storm days (NSD), the total accumulated cyclone energy (ACE), and the net tropical cyclone activity (NTCA) index for the 2014 hurricane season.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    One of the more interesting tropical-mid-latitude interactions is one that has important effects on precipitation within the Mediterranean basin. This interaction consists of an Atlantic tropical cyclone vestige whose original disturbance travels eastward and northward across Atlantic basin, eventually intermingling with a mid-latitude cyclone entering southern Europe and/or the \\bestern Mediterranean Sea. The period for these interactions is from mid-September through November. If the tropical cyclone and its vestige is able to make the eastward Atlantic transit within the low to mid-levels, or if an upper level potential vorticity perturbation Cjet streak) emitted by a Hurricane in its latter stages within the central Atlantic is able to propagate into and along the longwave pattern affecting the western Mediterranean Sea (MED), then there is the prospect for the tropical cyclone remnant to produce a major modification of the mid-latitude storm system preparing to affect the MED region. For such an occurrence to take place, it is necessary for an amplifying baroclinic perturbation to be already situated to the rear of a longwave trough, or to be excited by the emitted jet streak to the rear of a longwave trough -- in either case, preparing to affect the western MED. The Algiers City flood of 9-10 November 2001, which killed some 700 people, was produced by a Mediterranean cyclone that had been influenced by two vestige Atlantic tropical cyclones, 1,orenzo and Noel. A published modeling study involving various of this study's authors has already described the dynamical development of the Algiers storm as it amplified from a developing baroclinic disturbance in the Rossby wave train, into a northern Africa hazardous flood system, then lingered in the western MED as a semi-intense warm core cyclone. In our new modeling experiments, we investigate the impact of what might have happened in the eventual precipitation field. had the main features of the tropical cyclones NOT interacted with thc developing baroclinic disturbance as it penetrated the western MED. To do so, we first remove the moisture and dynamical features of the two vestigial tropical cyclones from the large scale meteorological fields used to initialize the Mediterranean cyclone simulation. This is done through depletion of the moisture front associated with the two tropical cyclones, accomplished by relaxation to the suppressed east Atlantic conditions. The dynamical effects are removed through energetic destruction of the latter stages of the eastward traveling tropical cyclones, accomplished by lowering the underlying sea surface temperatures. A precipitation-distribution impact experiment is then run by initializing with the customized large-scale fields. The final precipitation-impact field is described by differencing the "impact" run from the "control" run -- the latter defined as the original simulation which intrinsically includes the effects of the two vestigial tropical cyclones.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Truchelut, R.; Hart, R. E.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Lawrence, J. R.; Maddocks, R.

    2011-12-01

    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.

  13. Evolution of the Tropical Cyclone Integrated Data Exchange And Analysis System (TC-IDEAS)

    NASA Technical Reports Server (NTRS)

    Turk, J.; Chao, Y.; Haddad, Z.; Hristova-Veleva, S.; Knosp, B.; Lambrigtsen, B.; Li, P.; Licata, S.; Poulsen, W.; Su, H.; Tanelli, S.; Vane, D.; Vu, Q.; Goodman, H. M.; Blakeslee, R.; Conover, H.; Hall, J.; He, Y.; Regner, K.; Knapp, Ken

    2010-01-01

    The Tropical Cyclone Integrated Data Exchange and Analysis System (TC-IDEAS) is being jointly developed by the Jet Propulsion Laboratory (JPL) and the Marshall Space Flight Center (MSFC) as part of NASA's Hurricane Science Research Program. The long-term goal is to create a comprehensive tropical cyclone database of satellite and airborne observations, in-situ measurements and model simulations containing parameters that pertain to the thermodynamic and microphysical structure of the storms; the air-sea interaction processes; and the large-scale environment.

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

    PubMed

    Grimbacher, Peter S; Stork, Nigel E

    2009-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Hsiang, S. M.

    2009-12-01

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

  16. Radial-vertical profiles of tropical cyclone derived from dropsondes

    NASA Astrophysics Data System (ADS)

    Ren, Yifang

    The scopes of this thesis research are two folds: the first one is to the construct the intensity-based composite radial-vertical profiles of tropical cyclones (TC) using GPS-based dropsonde observations and the second one is to identify the major deficiencies of Mathur vortices against the dropsonde composites of TCs. The intensity-based dropsonde composites of TCs advances our understanding of the dynamic and thermal structure of TCs of different intensity along the radial direction in and above the boundary layer where lies the devastating high wind that causes property damages and storm surges. The identification of the major deficiencies of Mathur vortices in representing the radial-vertical profiles of TC of different intensity helps to improve numerical predictions of TCs since most operational TC forecast models need to utilize bogus vortices, such as Mathur vortices, to initialize TC forecasts and simulations. We first screen all available GPS dropsonde data within and round 35 named TCs over the tropical Atlantic basin from 1996 to 2010 and pair them with TC parameters derived from the best-track data provided by the National Hurricane Center (NHC) and select 1149 dropsondes that have continuous coverage in the lower troposphere. The composite radial-vertical profiles of tangential wind speed, temperature, mixing ratio and humidity are based for each TC category ranging from "Tropical Storm" (TS) to "Hurricane Category 1" (H1) through "Hurricane Category 5" (H5). The key findings of the dropsonde composites are: (i) all TCs have the maximum tangential wind within 1 km above the ground and a distance of 1-2 times of the radius of maximum wind (RMW) at the surface; (ii) all TCs have a cold ring surrounding the warm core near the boundary layer at a distance of 1-3 times of the RMW and the cold ring structure gradually diminishes at a higher elevation where the warm core structure prevails along the radial direction; (iii) the existence of such shallow cold ring outside the RMW explains why the maximum tangential wind is within 1 km above the ground and is outside the RMW, as required by the hydrostatic and gradient wind balance relations; (iv) one of the main differences among TCs of different intensity, besides the speed of the maximum tangential wind, is the vertical extent of near-saturated moisture air layer inside the core. A weaker TC tends to have a deep layer of the near-saturated moisture air layer whereas a stronger TC has a shallow one; (v) another main difference in the thermal structure among TCs of different intensity is the intensity and vertical extent of the warm core extending from the upper layer to the lower layer. In general, a stronger TC has a stronger warm core extending downward further into lower layer and vice versa. The features (iv) and (v) are consistent with the fact that a stronger TC tends to have stronger descending motion inside the core. The main deficiencies of Mathur vortices in representing the radial-vertical profiles of TC of different intensity are (i) Mathur vortices of all categories have the maximum wind at the surface; (ii) none of Mathur vortices have a cold ring outside the warm core near the boundary layer; (iii) Mathur vortices tend to overestimate warm core structure in reference to the horizontal mean temperature profile; (iv) Mathur vortices tend to overestimate the vertical depth of the near-saturated air layer near the boundary layer.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  18. Tropical cyclones in a T159 resolution global climate model: comparison with observations and re-analyses

    NASA Astrophysics Data System (ADS)

    Bengtsson, L.; Hodges, K. I.; Esch, M.

    2007-08-01

    Tropical cyclones have been investigated in a T159 version of the MPI ECHAM5 climate model using a novel technique to diagnose the evolution of the three-dimensional vorticity structure of tropical cyclones, including their full life cycle from weak initial vortices to their possible extra-tropical transition. Results have been compared with re-analyses [the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-yr Re-analysis (ERA40) and Japanese 25 yr re-analysis (JRA25)] and observed tropical storms during the period 1978-1999 for the Northern Hemisphere. There is no indication of any trend in the number or intensity of tropical storms during this period in ECHAM5 or in re-analyses but there are distinct inter-annual variations. The storms simulated by ECHAM5 are realistic both in space and time, but the model and even more so the re-analyses, underestimate the intensities of the most intense storms (in terms of their maximum wind speeds). There is an indication of a response to El Niño-Southern Oscillation (ENSO) with a smaller number of Atlantic storms during El Niño in agreement with previous studies. The global divergence circulation responds to El Niño by setting up a large-scale convergence flow, with the centre over the central Pacific with enhanced subsidence over the tropical Atlantic. At the same time there is an increase in the vertical wind shear in the region of the tropical Atlantic where tropical storms normally develop. There is a good correspondence between the model and ERA40 except that the divergence circulation is somewhat stronger in the model. The model underestimates storms in the Atlantic but tends to overestimate them in the Western Pacific and in the North Indian Ocean. It is suggested that the overestimation of storms in the Pacific by the model is related to an overly strong response to the tropical Pacific sea surface temperature (SST) anomalies. The overestimation in the North Indian Ocean is likely to be due to an over prediction in the intensity of monsoon depressions, which are then classified as intense tropical storms. Nevertheless, overall results are encouraging and will further contribute to increased confidence in simulating intense tropical storms with high-resolution climate models.

  19. 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

    Romps, David M.

    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

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

    SciTech Connect

    Broccoli, A.J.; Manabe, S.

    1990-10-01

    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.

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

    NASA Video Gallery

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

  2. TRMM Flyby of Tropical Cyclone Narelle - Duration: 15 seconds.

    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 ...

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Tropical Pacific sea surface temperature (SST) variability during the El Niño-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 Niño suppressing Atlantic tropical cyclones. The location of maximum SST warming during El Niño 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 Niño. Seasonal accumulated cyclone energy is used to evaluate the response in Atlantic tropical cyclone activity to Central and East Pacific El Niño, and the response in atmospheric conditions relevant for tropical cyclones is diagnosed using a genesis potential index.

  5. Northwest Australian tropical cyclones: Variability and seasonal prediction

    NASA Astrophysics Data System (ADS)

    Goebbert, Kevin Harold

    Global teleconnections, involving geopotential height, air temperature, and sea surface temperature, are found for the interannual variability of tropical cyclone (TC) activity in Northwest-Australian (NWAUS) basin of the Southeast Indian Ocean (105--135°E). The NWAUS basin averages 5.5 TCs per year, 42 TC days, and 3 TC landfalls. Additionally, a wavelet analysis yields wavelet power maximum in the 4--6 year and the decadal time periods for both yearly TC frequency and TC days. To identify significant correlates, the global atmospheric and oceanic parameters mentioned above were correlated with the TC frequency and TC days from the Woodside Petroleum Ltd. TC data set. Large correlations were obtained between the NWAUS TC frequency and the following variables: Apr--Jun 700-hPa geopotential heights over North America (r ˜ --0.64), May--Jul 850-hPa geopotential heights over the south Indian Ocean (r ˜ 0.60), May--Jul 850-hPa air temperature (r ˜ --0.63), Jun--Aug 925-hPa geopotential heights over the south Atlantic Ocean (r ˜ -0.65), and Jun--Aug 925-hPa geopotential heights over the Eastern Pacific Ocean (r ˜ --0.59). The collinearity among the five correlates are generally |r| < 0.4. Additionally, large correlations were obtained between the NWAUS TC days and the following variables: Jan--Mar 100-hPa v-component of the wind over the Southern Pacific Ocean (r ˜ 0.52), Apr-Jun 850-hPa geopotential heights over North America (r ˜ --0.58), and Jul--Sep 1000-hPa geopotential heights over the South Altanic Ocean (r ˜ --0.7). These variables can be utilized as seasonal predictors for the upcoming TC season in terms of frequency and days with a lead-time of at least three months for TC frequency and two months for TC days. This set of seasonal predictors includes, intra-basin, inter-basin, and cross-hemispheric regions, unlike previous Australian TC activity studies, which stress the primacy of ENSO. Here it is noted that the traditional Nino 3.4 and Nino 4 regions were not highly correlated with the NWAUS TC activity (| r| < 0.5). No local predictors based on SST, geopotential height, or air temperature resulted from the correlation analysis. The predictors are used in a multiple linear regression model for forecasting the coming seasons number of TCs and TC days. Finally, both prediction schemes are then compared to forecasts made using persistence, climatology, and random forecasts to determine if they perform better than these reference forecasts.

  6. Landfalling Tropical Cyclones: Forecast Problems and Associated Research Opportunities

    USGS Publications Warehouse

    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, Lingtian; Zehr, R.

    1998-01-01

    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.

  7. Tropical cyclones and the flood hydrology of Puerto Rico

    USGS Publications Warehouse

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

    2005-01-01

    Some of the largest unit discharge flood peaks in the stream gaging records of the U.S. Geological Survey (USGS) have occurred in Puerto Rico. Many of these flood peaks are associated with tropical cyclones. Hurricane Georges, which passed directly over the island on 21-22 September 1998, produced record flood peaks at numerous USGS stations in Puerto Rico. The hydrology and hydrometeorology of extreme flood response in Puerto Rico are examined through analyses of rainfall, based on Weather Surveillance Radar - 1988 Doppler (WSR-88D) radar reflectivity observations and USGS rain gage observations and discharge from USGS stream gaging stations. Peak rainfall accumulations of more than 700 mm occurred in the central mountain region of the island. The largest unit discharge flood peaks, however, were located in the eastern portion of the island in areas with smaller storm total rainfall accumulations but markedly larger rainfall rates at 5-60 min timescale. Orographic precipitation mechanisms played an important role in rainfall distribution over the island of Puerto Rico. Amplification of rainfall accumulations was associated with areas of upslope motion. Elevated low-level cloud water content in regions of upslope motion played an important role in the maximum rainfall accumulations in the central mountain region of Puerto Rico. The largest unit discharge flood peaks, however, were produced by a decaying eye wall mesovortex, which resulted in a 30-45 min period of extreme rainfall rates over the eastern portion of the island. This storm element was responsible for the record flood peak of the 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.

  8. Coastal boundary layer transition within tropical cyclones at landfall

    NASA Astrophysics Data System (ADS)

    Howard, James Robert

    Hurricanes pose a great risk to life and property with their high winds, excessive rainfall, wave action, and storm surge. Predicting changes within hurricanes at and near the time of landfall requires an understanding of the dynamics that drive the boundary layer flow. Forecasters predict the timing, duration, and effects of the intense winds associated with a hurricane when it comes ashore, while emergency management officials call for public evacuations based upon these forecasts. One region where understanding the magnitude and structure of the wind is critical is within the surface layer just downstream of the coastline in the onshore flow. Within this region the flow begins to adjust to changes in surface triggered by its passage from the shallow coastal waters to the less homogeneous and rougher land. This adjustment may include a slowing of the mean wind with an increase in turbulence, both resulting from the increased friction of the man-made and natural terrain. Hurricane observing programs consisting of portable and mobile equipment and regional coastal mesoscale observing networks are leading to a better understanding of the processes involved with these flow modifications. The Texas Tech University Wind Engineering Mobile Instrumented Tower Experiment (WEMITE) continues to play a leading role in the observation and analysis of the boundary layer of tropical cyclones at landfall. In order to gain further insight into the characteristics of this coastal transition zone, experiments were planned utilizing portable in-situ and remote measuring devices to be placed within the onshore flow at landfall. Experiment plan designs along with results from these experiments are discussed, including the analysis of a dataset collected by multiple institutions during the landfall of Hurricane Lili (2002) along the south-central Louisiana coast. Investigation reveals the existence of frictionally-induced changes in the boundary layer downwind of the coastline within the right semicircle with respect to Lili's forward motion. In the outer reaches of Lili, these transitions appear similar to internal boundary layers produced by flow moving over an abrupt change in surface. The impact on the magnitude of the wind within this near-shore region is a reduction of 4--10% per 10 km distance from the coast up to 50 km inland for open terrain. Results of the study show this reduction to be an exponential function of distance from the coast, which is dependent upon surface roughness. This rate of wind decay slows with farther progression inland and appears to be much faster than the rate found in some modeling studies. In contrast, near Lili's circulation center, little or no decrease in the magnitude of the mean wind was found for distances of up to 20 km inland.

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

    E-print Network

    Fahad, Abdullah Al

    2015-01-01

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

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

    PubMed Central

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

    2013-01-01

    Tropical cyclones have been hypothesized to influence climate by pumping heat into the ocean, but a direct measure of this warming effect is still lacking. We quantified cyclone-induced ocean warming by directly monitoring the thermal expansion of water in the wake of cyclones, using satellite-based sea surface height data that provide a unique way of tracking the changes in ocean heat content on seasonal and longer timescales. We find that the long-term effect of cyclones is to warm the ocean at a rate of 0.32 ± 0.15 PW between 1993 and 2009, i.e., ?23 times more efficiently per unit area than the background equatorial warming, making cyclones potentially important modulators of the climate by affecting heat transport in the ocean–atmosphere system. Furthermore, our analysis reveals that the rate of warming increases with cyclone intensity. This, together with a predicted shift in the distribution of cyclones toward higher intensities as climate warms, suggests the ocean will get even warmer, possibly leading to a positive feedback. PMID:23922393

  11. An atlas of 1976 GEOS-3 radar altimeter data for tropical cyclone studies

    NASA Technical Reports Server (NTRS)

    Stanley, H. R.; Chan, B.; Givens, C.; Taylor, R.

    1979-01-01

    The means for locating and extracting GEOS-3 altimeter data acquired for the analysis of specific hurricanes, typhoons, and other tropical cyclones are presented. These data are also expected to be extremely useful in the analysis of the behavior of the altimeter instrument in the presence of severe meteorological disturbances as well as provide a data base which can be useful in the resolution of apparently anomalous geoid or sea surface characteristics. Geographic locations of 1976 tropical cyclones were correlated with the closest approaching orbits of the GEOS-3 satellite and its radar altimeter. The cyclone locations and altimeter data were correlated for the 1976 season. The area of coverage includes the northern hemisphere. This document is a sequel to NASA TM-X-69364 which covered the majority of the 1975 season.

  12. Improvement of Precipitation Retrieval for Tropical Cyclones from Passive Microwave Observations

    NASA Astrophysics Data System (ADS)

    Kitani, K. M.; Shige, S.

    2012-12-01

    In this paper, we improve a passive microwave precipitation algorithm, the Global Satellite Mapping of Precipitation (GSMaP) algorithm [Aonashi et al., 2009, JMSJ]. GSMaP is available for many airborne microwave radiometers (MWRs) such as Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI). GSMaP comprises two parts: forward calculation and retrieval. In forward calculation, lookup tables (LUTs) or databases showing the relationship between rainfall and MWR brightness temperatures (TBs) are produced using radiative transfer models. Retrieval consists of a rain/no-rain classification and estimation of the rainfall rates with LUTs. The algorithm uses precipitation-related variable models (precipitation profiles, drop-size distribution, etc.). TRMM Precipitation Radar (TRMM/PR) profiles are classified into 10 types (six over land, four over ocean and coast) using the PR precipitation parameters (rain area, stratiform rain-area fraction, precipitation-top level, etc.) and the ratio between the PR precipitation rates and Lightning Imaging Sensor (LIS) flash rates. GSMaP team produces convective and stratiform precipitation profiles for these types by averaging the PR convective and stratiform precipitation profiles over prescribed rainfall bins for each type. In this averaging they use profiles relative to freezing level height (FLH) in order to exclude the influence of atmospheric temperature variations. The LUTs are calculated with the precipitation profile of the dominant precipitation type for every 5 x 5 degree point and 3 month. Tropical cyclones (TCs) are not included in 10 types. In this study, we compared the profiles between TCs and current ocean precipitation types and applied to GSMaP algorithm to improve estimation of rainfall of TCs. We analyzed TCs from Sep. 2001 to Aug. 2010 after TRMM boost. We used JAXA/EORC Tropical Cyclone Database 2A25 produced and supplied by the Earth Observation Research and application Center, Japan Aerospace Exploration Agency (JAXA/EORC). The locations and strengths of TCs were obtained from Joint Typhoon Warning Center and National Hurricane Center data. The profile of TC was taller than current tropical ocean precipitation types (shallow rain, organized system, transition zone). There ware significant differences between convective profiles for weak rain bins. Categorizing data according to the strength of TC and the distance from the storm center, the rain intensity at FLH near the cyclone center of category 3-5 for surface rain 1.0 mm/h was more than 5.0 mm/h. Convective profiles for strong rain bins of weaker TCs were taller than that of stronger TCs. We calculated the LUTs of TCs, leading to distinguished structure of eyes of TC though the eye and eyewall of TC looks blur in the original. We are planning to perform in-depth analysis of images of TCs from MWRs for further improvement of rainfall retrieval.

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

    PubMed

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

    2014-01-01

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

  14. GPM Flyby of Tropical Cyclone Ula's Eye and Rainfall - Duration: 15 seconds.

    NASA Video Gallery

    NASA Sees Tropical Cyclone Ula's Eye and Rainfall On Dec. 29, NASA's GPM saw rain was falling at a rate of over 83.6 mm (3.29 inches) per in a feeder band (of thunderstorms) northeast of the develo...

  15. Upper Oceanic Energy Response to Tropical Cyclone Passage JOHN A. KNAFF AND MARK DEMARIA

    E-print Network

    Schubert, Wayne H.

    that the primary energy source for tropical cyclones (TCs) is the ocean (e.g., Palme´n 1948; Riehl 1950). Latent as the primary TC energy source. As the potential intensity concept developed, Corresponding author address: John fluxes are func- tions of air­sea temperature differences, wind speeds, and relative humidity. As a TC

  16. North American Tropical Cyclone Landfall and SST: A Statistical Model Study TIMOTHY HALL

    E-print Network

    are related to anthropogenic climate change and/or natural climate cycles. North Atlantic (NA) sea surface of the twenty-first century using the Intergov- ernmental Panel on Climate Change (IPCC) models produce widely cycle of North Atlantic (NA) tropical cyclones (TCs) is used to examine the relationship between climate

  17. Momentum Flux Budget across the AirSea Interface under Uniform and Tropical Cyclone Winds

    E-print Network

    Rhode Island, University of

    Momentum Flux Budget across the Air­Sea Interface under Uniform and Tropical Cyclone Winds YALIN April 2010) ABSTRACT In coupled ocean­atmosphere models, it is usually assumed that the momentum flux (decays) in space or time, it gains (loses) momentum and reduces (increases) the momentum flux

  18. 13.5 THE IMPORTANCE OF THE PRECIPITATION MASS SINK IN TROPICAL CYCLONES Richard M. Yablonsky*

    E-print Network

    Rhode Island, University of

    , the mass inflow (outflow) per unit volume must equal the rate of mass increase (decrease) per unit volume13.5 THE IMPORTANCE OF THE PRECIPITATION MASS SINK IN TROPICAL CYCLONES Richard M. Yablonsky* North, Raleigh, North Carolina 1. INTRODUCTION AND BACKGROUND Traditionally, the concept of mass conservation

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

    E-print Network

    Jiang, Haiyan

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

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

    E-print Network

    Thompson, Anne

    Effects of Vertical Wind Shear on the Predictability of Tropical Cyclones FUQING ZHANG AND DANDAN methods. A recent study by Zhang et al. (2011) showed that the hurricane intensity forecast ac- curacy can chaotic, less well understood, and intrinsically less predictable. The recent study of Zhang and Sippel

  1. Tropical cyclones and permanent El Nino in the early Pliocene epoch

    E-print Network

    Fedorov, Alexey V.

    Tropical cyclones (also known as hurricanes and typhoons) are now believed to be an important component of the Earth’s climate system1, 2, 3. In particular, by vigorously mixing the upper ocean, they can affect the ocean’s ...

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2008-01-01

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

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

    E-print Network

    Lee, Keun-Hee

    2012-02-14

    as polluted case but with a modified shortwave radiation scheme. The polluted and AR cases have much larger amounts of cloud water and water vapor in troposphere, and the increased cloud water can freeze to produce ice water paths. A tropical cyclone...

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

    E-print Network

    Long, David G.

    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

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

    E-print Network

    Kossin, James P.

    LETTER doi:10.1038/nature10552 Arabian Sea tropical cyclones intensified by emissions of black Throughout the year, average sea surface temperatures in the Arabian Sea are warm enoughto supportthe- culation over the Arabian Sea6­9 . In principle, this aerosol-driven circulation modification could affect

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

    E-print Network

    2008-01-01

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

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

    E-print Network

    Tregoning, Paul

    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

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

    E-print Network

    Grissino-Mayer, Henri D.

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

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

    E-print Network

    Miami, University of

    School of Marine and Atmospheric Science Coral Gables, Florida deep convection and a closed surface wind circulation about a well-defined center. Once formed, a tropical cyclone is maintained by the extraction of heat energy from the ocean at high temperature and heat

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

    PubMed

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

    2014-01-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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 18O/16O 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 AD1700. 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.

  12. Remote impact of blocking highs on the sudden track reversal of tropical cyclones

    NASA Astrophysics Data System (ADS)

    Luo, Xia; Jianfang, Fei; Xiaogang, Huang; Cheng, Xiaoping; Yu, Kun

    2015-11-01

    Previous work showed that some tropical cyclones (TCs) in the western Pacific Ocean undergo sudden track reversal, and the onset, maintenance and decay of blocking highs (BHs) coexisted with 19 of the studied TCs with sudden track reversal. In these cases, the phase relations between the BH, the continental high (CH), the subtropical high (SH) and the suddenly reversed TCs could be classified into types A, B, C and D. Types C and D were the focal point of this follow-up study, in which Typhoon Pabuk (2007) and Lupit (2009) were employed to conduct numerical simulations. The results showed that the reversed tracks of Pabuk (2007) and Lupit (2009) could have been affected by the BH, particularly in terms of the turning location and the trend of movement after turning. Specifically, the two main features for Pabuk (2007) in the BH perturbations were the deflection of its turning point and a distinct anticlockwise rotation. Lupit (2009) deviated to the southwest and finally made landfall in the Philippines, or experienced further eastward movement, in the perturbed BH. The impact mechanisms can be attributed to the change in the vorticity field transported from the BH, leading to an intensity variation of midlatitude systems. BHs may have a positive feedback effect on the strength of the westerly trough (TR), as indicated by a weakened and strengthened TR corresponding to negative and positive BH perturbations, respectively.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  14. 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

    Miami, University of

    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 cyclones need warm water to survive. From an atmospheric science perspective, the minimum sea surface

  15. On the factors affecting trends and variability in tropical cyclone potential intensity

    NASA Astrophysics Data System (ADS)

    Wing, Allison A.; Emanuel, Kerry; Solomon, Susan

    2015-10-01

    Tropical cyclone potential intensity (Vp) is controlled by thermodynamic air-sea disequilibrium and thermodynamic efficiency, which is a function of the sea surface temperature and the tropical cyclone's outflow temperature. Observed trends and variability in Vp in each ocean basin are decomposed into contributions from these two components. Robustly detectable trends are found only in the North Atlantic, where tropical tropopause layer (TTL) cooling contributes up to a third of the increase in Vp. The contribution from disequilibrium dominates the few statistically significant Vp trends in the other basins. The results are sensitive to the data set used and details of the Vp calculation, reflecting uncertainties in TTL temperature trends and the difficulty of estimating Vp and its components. We also find that 20-71% of the interannual variability in Vp is linked to the TTL, with correlations between detrended time series of thermodynamic efficiency and Vp occurring over all ocean basins.

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

    NASA Astrophysics Data System (ADS)

    Pattantyus, Andre; Businger, Steven

    2014-06-01

    On 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.

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

    PubMed

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

    2015-01-01

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

  18. Stable Isotope Anatomy of Tropical Cyclone Ita, North-Eastern Australia, April 2014

    PubMed Central

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

    2015-01-01

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

  19. Palaeotempestology: the study of prehistoric tropical cyclones--a review and implications for hazard assessment.

    PubMed

    Nott, Jonathan

    2004-05-01

    Records of prehistoric tropical cyclones occur in the form of ridges of coral rubble, sand, shell, sand and shell, and pumice; erosional terraces in raised gravel beaches; barrier washover deposits; and, sediments deposited in the shallow offshore marine environment. Other less well-documented records occur as variations in isotopic ratios within speleothems and possibly tree rings, and changes in pollen records resulting from introduction of new species after forest disturbance due to cyclonic winds. As yet, such records have not been identified beyond 5500 years of age. Recent palaeotempestological studies in the United States and northern Australia have highlighted that the frequency and magnitude of these natural hazards do not remain constant over time, and there are periods when cyclogenesis is enhanced, and others of relative quiescence. Recognition of such regime changes, or non-stationarity in the long-term record, is important for risk assessments of this hazard. Until now however, few if any risk assessments have incorporated data from the long-term record of tropical cyclones, and instead have relied on generally short instrumented historical records. The longer-term records suggest that such an approach may miscalculate the 1% Annual Exceedance Probability risk to coastal communities from future tropical cyclones. PMID:14987874

  20. Tropical cyclone activity and western North Atlantic stratification over the last millennia and potential connections (Invited)

    NASA Astrophysics Data System (ADS)

    Woodruff, J. D.; Sriver, R. L.; Lund, D. C.

    2010-12-01

    Tropical cyclones are recognized to modify the thermal structure of the upper ocean through vertical mixing. Assessing the role this mixing plays in the overall stratification of the upper ocean is difficult, however, due to the relatively short and incomplete instrumental record. Recent works indicate that proxies for both hurricane landfalls and oceanographic stratification are preserved within the geologic record, and may help to assess interconnections prior to the 20th century. Here we present results from a growing network of paleo-hurricane reconstructions from the Western North Atlantic that exhibit significant changes in activity over the last few millennia. A prominent lull in activity is observed prior to approximately 250-300 years ago that extends back several centuries. Paleo-reconstructions of ocean density from the Western North Atlantic also indicate an increase in vertical stratification during this same interval, potentially due to reduced hurricane frequency. Numerical simulations of ocean mixing under an idealized scenario of diminished cyclone wind forcing reproduce a measurable fraction of the density anomalies observed within the paleo-record during reduced hurricane activity. Results support changes in tropical cyclone activity having a direct effect on past ocean stratification in the western North Atlantic, and suggest that climate scenarios with altered tropical cyclone activity may exhibit noticeable differences in vertical density structure.

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

    E-print Network

    Sieron, Scott B.

    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 ...

  2. Long-term variations of North Atlantic tropical cyclone activity downscaled from a coupled model simulation of the last millennium

    E-print Network

    Kozar, Michael E.

    The observed historical record of North Atlantic tropical cyclones (TCs) is relatively short and is subject to potential biases owing to a lack of observation platforms such as aircraft reconnaissance and satellite imagery ...

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

    E-print Network

    Wang, Yuqing

    Response of Tropical Cyclone Potential Intensity to a Global Warming Scenario in the IPCC AR4 CGCMs environment. Holland (1997) noted that the very strongest TCs observed in recent history seem to have attained

  4. Relationships between tropical cyclone intensity and satellite based indicators of inner core convection: 85 GHz ice scattering signature and lightning 

    E-print Network

    Cecil, Daniel Joseph

    1997-01-01

    A key component in the maintenance and intensification of tropical cyclones is the transverse circulation, which transports mass and momentum and provides latent heat release via inner core convective updrafts. This study examines these updrafts...

  5. Convective and rainfall properties of tropical cyclone inner cores and rainbands in relation to tropical cyclone intensity changes using eleven years of Tropical Rainfall Measuring Mission data

    NASA Astrophysics Data System (ADS)

    Ramirez, Ellen Michelle

    Covering December 1997 through December 2008, over 13,000 tropical cyclone (TC) overpasses of 945 TCs by the Tropical Rainfall Measuring Mission (TRMM) satellite are used to document the observed passive microwave ice scattering magnitudes, radar reflectivity, IR cloud top height, total lightning, and derived rainfall parameters including rain rate, raining area, and volumetric rain. A semimanual method is used to divide TC raining area into inner core (IC), inner rainband (IB), and outer rainband (OB) regions. Precipitation features (PFs) within these regions are compared for their convective vigor and rainfall characteristics based on passive microwave, IR, radar, and lightning properties. These properties in the IC region are further examined in terms of different TC intensity and intensity change categories. TC intensity categories include tropical depressions (TDs), tropical storms (TSs), category 1-2 hurricanes (CAT12s), and category 3-5 hurricanes (CAT35s). The 24-h TC intensity change categories include weakening (W), neutral (N), slowly intensifying (SI), and rapidly intensifying (RI). The stronger tails of the convective intensity distributions are found to be similar for features in both the IC and OB regions, while the features in the IB region yield the weakest convective signatures. However, at the middle to weaker end of the convective spectrum, ice scattering signatures and reflectivity profiles are the strongest for features in the IC region, followed by those in the IB, then those in the OB. The same order is found for the whole distribution spectrum of feature conditional mean rain rates in these regions. The convective intensity of features in the IC region are found to increase as storm intensity increases, except at the strongest end of the spectrum, where ice scattering signatures and reflectivity profiles are stronger in features associated with TS and TD strength storms rather than those associated with hurricane strength storms. The IC conditional mean rain rate and volumetric rain increase as storm intensity increases. It is found that necessary conditions for RI are that the minimum 85 GHz PCT in the IC region must be less than 256 K and the minimum 37 GHz PCT must be less than 275 K. Over 98% of RI minimum 11im brightness temperatures in the IC region are less than 212 K. RI storms always have larger raining area and volumetric rain in the IC region than storms in other intensity change categories.

  6. TROPICAL CYCLONE RESEARCH REPORT TCRR 15-2: 110 (2015)

    E-print Network

    Smith, Roger K.

    2015-01-01

    . A traditional and much used sounding for the North Atlantic and Caribbean Sea has been the Jordan mean sounding of the Jordan sounding, noting that the tropical atmosphere in the North Atlantic Ocean and Caribbean Sea of the thermodynamics and kinematics that exist in the tropical North Atlantic Ocean and Caribbean Sea during

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  9. An atlas of 1977 and 1978 GEOS-3 radar altimeter data for tropical cyclone studies

    NASA Technical Reports Server (NTRS)

    Stanley, H. R.; Taylor, R. L.

    1980-01-01

    All of the GEOS 3 satellite altimeter schedule information were collected with all of the available 1977 and 1978 tropical cyclone positional information. The time period covers from March 23, 1977 through Nov. 23, 1978. The geographical region includes all ocean area north of the equator divided into the following operational areas: the Atlantic area (which includes the Caribbean and Gulf of Mexico); the eastern Pacific area; the central and western Pacific area; and the Indian Ocean area. All available source material concerning tropical cyclones was collected. The date/time/location information was extracted for each disturbance. This information was compared with the GEOS 3 altimeter ON/OFF history information to determine the existence of any altimeter data close enough in both time and location to make the data potentially useful for further study (the very liberal criteria used was time less than 24 hours and location within 25 degrees). Geographic plots (cyclone versus GEOS 3 orbit track) were produced for all of the events found showing the approximate location of the cyclone and the GEOS 3 orbit traces for the full day.

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    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.

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

    E-print Network

    Poh, Chung-How

    2014-01-01

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

  12. The role of the equivalent blackbody temperature in the study of Atlantic Ocean tropical cyclones

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Satellite measured equivalent blackbody temperatures of Atlantic Ocean tropical cyclones are used to investigate their role in describing the convection and cloud patterns of the storms and in predicting wind intensity. The high temporal resolution of the equivalent blackbody temperature measurements afforded with the geosynchronous satellite provided sequential quantitative measurements of the tropical cyclone which reveal a diurnal pattern of convection at the inner core during the early developmental stage; a diurnal pattern of cloudiness in the storm's outer circulation throughout the life cycle; a semidiurnal pattern of cloudiness in the environmental atmosphere surrounding the storms during the weak storm stage; an outward modulating atmospheric wave originating at the inner core; and long term convective bursts at the inner core prior to wind intensification.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  14. Improving Ku-band Scatterometer Ocean Surface Wind Direction Retrievals in Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Foster, R. C.; Zhang, J.; Black, P. G.

    2014-12-01

    Tropical cyclones are regions of very strong rain and very high winds, both of which present major challenges to surface wind vector retrieval from Ku-band scatterometers. Wind speed and wind direction retrievals can incur severe errors in regions of high rain rates. One particular signature of rain contamination is wind directions in the across-swath direction, which often leads to displaced circulation centers. Recently, Stiles et al. (2014) developed a method for retrieving QuikSCAT tropical cyclone wind speeds using a neural network approach that was tuned using H*WIND surface wind analyses and passive microwave-estimated rain rates from satellites. We are developing a scene-wide methodology by which a set of dynamically-consistent wind directions can be estimated from these wind speeds. The method is based on an iterative use of a tropical cyclone-specific sea-level pressure retrieval technique that we developed. The sea-level pressure analysis uses a boundary layer model that includes the dynamical shallowing of the tropical cyclone boundary layer toward the storm center, a roll-off in surface drag at high wind speeds, and, storm motion-corrected nonlinear mean flow advection effects. Scene-wide consistency is enforced by the integral nature (with respect to the surface wind vector field) of the derived surface pressure pattern and a constraint that the geostrophic contribution to the total flow is non-divergent. We are currently developing methods to evaluate the retrieved wind directions based on HRD aircraft observations and a limited-domain wind vector partitioning of the retrieved wind vectors into irrotational, non-divergent, and, background flow deformation contributions.

  15. Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era.

    PubMed

    Reed, Andra J; Mann, Michael E; Emanuel, Kerry A; Lin, Ning; Horton, Benjamin P; Kemp, Andrew C; Donnelly, Jeffrey P

    2015-10-13

    In a changing climate, future inundation of the United States' Atlantic coast will depend on both storm surges during tropical cyclones and the rising relative sea levels on which those surges occur. However, the observational record of tropical cyclones in the North Atlantic basin is too short (A.D. 1851 to present) to accurately assess long-term trends in storm activity. To overcome this limitation, we use proxy sea level records, and downscale three CMIP5 models to generate large synthetic tropical cyclone data sets for the North Atlantic basin; driving climate conditions span from A.D. 850 to A.D. 2005. We compare pre-anthropogenic era (A.D. 850-1800) and anthropogenic era (A.D.1970-2005) storm surge model results for New York City, exposing links between increased rates of sea level rise and storm flood heights. We find that mean flood heights increased by ?1.24 m (due mainly to sea level rise) from ?A.D. 850 to the anthropogenic era, a result that is significant at the 99% confidence level. Additionally, changes in tropical cyclone characteristics have led to increases in the extremes of the types of storms that create the largest storm surges for New York City. As a result, flood risk has greatly increased for the region; for example, the 500-y return period for a ?2.25-m flood height during the pre-anthropogenic era has decreased to ?24.4 y in the anthropogenic era. Our results indicate the impacts of climate change on coastal inundation, and call for advanced risk management strategies. PMID:26417111

  16. Analysis of tropical cyclone dynamics in two models of different complexity

    NASA Astrophysics Data System (ADS)

    Schönemann, D. B.; Frisius, T.

    2012-04-01

    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.

  17. Impact of anthropogenic climate change on North Atlantic tropical cyclone activity simulated by regional coupled AOGCM

    NASA Astrophysics Data System (ADS)

    Sein, D.; Mikolajewicz, U.; Jacob, D.

    2012-12-01

    The global general circulation models involved in IPCC simulations are usually too coarse to reproduce many smaller scale processes like tropical cyclones. We present a novel approach to downscale climate change scenarios which could be also used to investigate the generation and propagation of hurricanes over the North Atlantic. The REgional atmosphere MOdel REMO is coupled to the global ocean - sea ice - marine biogeochemistry model MPIOM/HAMOCC with increased resolution in the North Atlantic. The coupled domain includes the North Atlantic and the Arctic Ocean. The models are coupled via the OASIS coupler. Exchange between ocean and atmosphere was made every hour. Lateral atmospheric and upper oceanic boundary conditions outside the coupled domain were prescribed using ECHAM5/MPIOM C20 20-th century and A1B scenario data (the total simulation period was 1920-2100). The model was spun-up for the period 1920-2000. Then the scenario run (21st century) and in parallel a control run (20th century forcing) were carried out. Here we present the results of the dynamical downscaling approach. The tropical cyclones activity was analyzed for both the 20 century and 21st century A1B projection. Comparison between the last decades of 20 and 21st century shows both an increase of tropical cyclones activity in the future as well as a clear northward shift of their trajectories.

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

    PubMed

    Pezza, Alexandre Bernardes; Simmonds, Ian

    2008-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  2. Interannual variation of multiple tropical cyclone events in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Gao, Jianyun; Li, Tim

    2012-11-01

    The interannual variability of occurrence of multiple tropical cyclone (MTC) events during June-October in the western North Pacific (WNP) was examined for the period 1979-2006. The number of the MTC events ranged from 2 to 9 per year, exhibiting a remarkable year-to-year variation. Seven active and seven inactive MTC years were identified. Compared to the inactive years, tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years. A composite analysis shows that inactive MTC years were often associated with the El Niño decaying phase, as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature (SST) anomalies in the concurrent summer. Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region. In addition to the mean flow difference, significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation (ISO). Compared with inactive MTC years, ISO activity was much stronger along the equator and in the WNP region during active MTC years. Both westward- and northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years. The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events.

  3. Arguments to question Emanuel's hypothesis on the central role of tropical cyclones in driving the MOC are presented in attached papers.

    E-print Network

    Miami, University of

    cyclones in driving the MOC are presented in attached papers. (1) Nilsson cyclone-induced mixing an cooling, in particular the 3rd and 4th baroclinic modes of Jaimes and Shay (2009) represents the upper and lower bounds for tropical-cyclone

  4. Impacts of tropical cyclones on U.S. forest tree mortality and carbon flux from 1851 to 2000

    PubMed Central

    Zeng, Hongcheng; Chambers, Jeffrey Q.; Negrón-Juárez, Robinson I.; Hurtt, George C.; Baker, David B.; Powell, Mark D.

    2009-01-01

    Tropical cyclones cause extensive tree mortality and damage to forested ecosystems. A number of patterns in tropical cyclone frequency and intensity have been identified. There exist, however, few studies on the dynamic impacts of historical tropical cyclones at a continental scale. Here, we synthesized field measurements, satellite image analyses, and empirical models to evaluate forest and carbon cycle impacts for historical tropical cyclones from 1851 to 2000 over the continental U.S. Results demonstrated an average of 97 million trees affected each year over the entire United States, with a 53-Tg annual biomass loss, and an average carbon release of 25 Tg y?1. Over the period 1980–1990, released CO2 potentially offset the carbon sink in forest trees by 9–18% over the entire United States. U.S. forests also experienced twice the impact before 1900 than after 1900 because of more active tropical cyclones and a larger extent of forested areas. Forest impacts were primarily located in Gulf Coast areas, particularly southern Texas and Louisiana and south Florida, while significant impacts also occurred in eastern North Carolina. Results serve as an important baseline for evaluating how potential future changes in hurricane frequency and intensity will impact forest tree mortality and carbon balance. PMID:19416842

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  6. Interannual and cyclone-driven variability in phytoplankton communities of a tropical coastal lagoon.

    PubMed

    Srichandan, Suchismita; Kim, Ji Yoon; Kumar, Abhishek; Mishra, Deepak R; Bhadury, Punyasloke; Muduli, Pradipta R; Pattnaik, Ajit K; Rastogi, Gurdeep

    2015-12-15

    One of the main challenges in phytoplankton ecology is to understand their variability at different spatiotemporal scales. We investigated the interannual and cyclone-derived variability in phytoplankton communities of Chilika, the largest tropical coastal lagoon in Asia and the underlying mechanisms in relation to environmental forcing. Between July 2012 and June 2013, Cyanophyta were most prolific in freshwater northern region of the lagoon. A category-5 very severe cyclonic storm (VSCS) Phailin struck the lagoon on 12th October 2013 and introduced additional variability into the hydrology and phytoplankton communities. Freshwater Cyanophyta further expanded their territory and occupied the northern as well as central region of the lagoon. Satellite remote sensing imagery revealed that the phytoplankton biomass did not change much due to high turbidity prevailing in the lagoon after Phailin. Modeling analysis of species-salinity relationship identified specific responses of phytoplankton taxa to the different salinity regime of lagoon. PMID:26611863

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

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  9. 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

    Fiorino, M.; Goerss, J.S.; Jensen, J.J.; Harrison, E.J. Jr. Naval Research Lab., Monterey, CA Fleet Numerical Oceanography Center, Monterey, CA ARC Professional Services Group, Inc., Landover, MD )

    1993-03-01

    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.

  10. 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)

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

    1993-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Geiger, Tobias; Levermann, Anders; Frieler, Katja

    2015-04-01

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

  12. Analysis of North Atlantic tropical cyclone intensify change using data mining

    NASA Astrophysics Data System (ADS)

    Tang, Jiang

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

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

    NASA Astrophysics Data System (ADS)

    Klose, C. D.

    2011-12-01

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

  14. Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 140: 792804, April 2014 Sensitivity of tropical-cyclone models to the surface drag

    E-print Network

    Smith, Roger K.

    2014 Sensitivity of tropical-cyclone models to the surface drag coefficient in different boundary. The recent study of the sensitivity of tropical-cyclone intensification to the surface drag coefficient in a three-dimensional model by Montgomery et al. is extended to include a wind-speed-dependent drag

  15. An Analysis of North Atlantic Tropical Cyclones and Their Impacts on Coastal Inundation in New York and New Jersey during the Last Millennium

    NASA Astrophysics Data System (ADS)

    Reed, A. J.; Mann, M. E.; Emanuel, K.; Lin, N.; Kemp, A.; Horton, B.

    2014-12-01

    In a changing climate, future inundation of the United States Atlantic and Gulf coasts will depend on the combined effect of storm surges during tropical cyclones and the rising sea levels on which those surges occur. The observational record of tropical cyclones in the Atlantic basin is too short (AD 1851-present) to allow for accurate assessment of long-term trends in storm activity. In order to overcome the limitations of the short observational record of tropical cyclones in the Atlantic, we downscaled four CMIP5 models to generate synthetic tropical cyclone data sets for the Atlantic basin that span from AD 850 to AD 2005. Using an interdisciplinary approach that combines these tropical cyclone simulations with storm surge models and local proxy sea-level reconstructions of the last two millennia, we provide insight into the connections between climate change, sea-level rise, tropical cyclones, and coastal flooding events like Hurricane Sandy of 2012. We present a comparison of pre-anthropogenic era (before AD 1800) and anthropogenic era (since AD 1800) storm surge model results from the New York/New Jersey region, exposing links between increased rates of sea-level rise and storm surge heights. An analysis of the characteristics and metrics of the tropical cyclones that create storm surges in this region is also performed. Results of this work will be a step towards improved scientific prediction of coastal inundation as a result of sea-level rise and tropical cyclones in our changing climate.

  16. 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

    Kossin, James P.

    2007-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. A review of tropical cyclone-generated storm surges: Global data sources, observations, and impacts

    NASA Astrophysics Data System (ADS)

    Needham, Hal F.; Keim, Barry D.; Sathiaraj, David

    2015-06-01

    Tropical cyclone-generated storm surges are among the world's most deadly and destructive natural hazards. This paper provides the first comprehensive global review of tropical storm surge data sources, observations, and impacts while archiving data in SURGEDAT, a global database. Available literature has provided data for more than 700 surge events since 1880, the majority of which are found in the western North Atlantic (WNA), followed by Australia/Oceania, the western North Pacific (WNP), and the northern Indian Ocean (NIO). The Bay of Bengal (BOB) in the NIO consistently observes the world's highest surges, as this subbasin averages five surges ?5 m per decade and has observed credible storm tide levels reaching 13.7 m. The WNP observes the highest rate of low-magnitude surges, as the coast of China averages 54 surges ?1 m per decade, and rates are likely higher in the Philippines. The U.S. Gulf Coast observes the second highest frequency of both high-magnitude (?5 m) and low-magnitude (?1 m) surges. The BOB observes the most catastrophic surge impacts, as 59% of global tropical cyclones that have killed at least 5000 people occurred in this basin. The six deadliest cyclones in this region have each killed at least 140,000 people, and two events have killed 300,000. Storm surge impacts transportation, agriculture, and energy sectors in the WNA. Oceania experiences long-term impacts, including contamination of fresh water and loss of food supplies, although the highest surges in this region are lower than most other basins.

  20. Tropical Cyclones and Climate Controls in the Western Atlantic Basin during the First Half of the Nineteenth Century

    NASA Astrophysics Data System (ADS)

    Mock, C. J.; Dodds, S. F.; Rodgers, M. D.; Patwardhan, A.

    2008-12-01

    This study describes new comprehensive reconstructions of individual Western Atlantic Basin tropical cyclones for each year of the first half of the nineteenth century in the Western Atlantic Basin that are directly compatible and supplement the National Hurricane Center's HURDAT (Atlantic basin hurricane database). Data used for reconstructing tropical cyclones come from ship logbooks, ship protests, diaries, newspapers, and early instrumental records from more than 50 different archival repositories in the United States and the United Kingdom. Tropical cyclone strength was discriminated among tropical storms, hurricanes, major hurricanes, and non-tropical lows at least at tropical storm strength. The results detail the characteristics of several hundred storms, many of them being newly documented, and tracks for all storms were mapped. Overall, prominent active periods of tropical cyclones are evident along the western Atlantic Ocean in the 1830s but Caribbean and Gulf coasts exhibit active periods as being more evident in the 1810s and 1820s. Differences in decadal variations were even more pronounced when examining time series of activity at the statewide scale. High resolution paleoclimate and historical instrumental records of the AMO, NAO, ENSO, Atlantic SSTs, West African rainfall, and volcanic activity explain how different modes in these forcing mechanisms may explain some of the multidecadal and interannual variations. The early nineteenth century active hurricane activity appears to be particularly unique in corresponding with a low (negative index) AMO period, and as they relate to particular synoptic-scale patterns in the latter part of the Little Ice Age. Model simulations offer some hypotheses on such patterns, perhaps suggesting increased baroclinic-related storms and a slight later possible shift in the seasonal peak of tropical cyclones for some areas at times. Some years, such as 1806, 1837, 1838, 1842, and 1846 have particularly very active seasons, and we critically examined the synoptic-scale circulation responsible and also related some of the storms as they relate to potential modern analogs.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Tropical cyclone rainfall as measured by the Nimbus 5 electrically scanning microwave radiometer

    NASA Technical Reports Server (NTRS)

    Allison, L. J.; Wilheit, T. T.; Rodgers, E. B.; Fett, R. W.

    1974-01-01

    A selected group of 1973 North Pacific Ocean tropical cyclones was studied by using data from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR), the Temperature-Humidity Infrared Radiometer (THIR), NOAA-2 and USAF DMSP imageries. From the unique combination of infrared, visible, and microwave data, it was possible during various stages of storm development to differentiate between dense cirrus outflow and rain areas, to identify centers of circulation and areas of low-level moisture, and by the use of a theoretical model to estimate semi-quantitatively areas of light, moderate, and heavy rainfall rates.

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

    NASA Technical Reports Server (NTRS)

    Kidder, S. Q.

    1979-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Lawrence, James R.

    2004-01-01

    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

  6. Further examination of the thermodynamic modification of the inflow layer of tropical cyclones by vertical wind shear

    NASA Astrophysics Data System (ADS)

    Riemer, M.; Montgomery, M. T.; Nicholls, M. E.

    2013-01-01

    Recent work has developed a new framework for the impact of vertical wind shear on the intensity evolution of tropical cyclones. A focus of this framework is on the frustration of the tropical cyclone's power machine by shear-induced, persistent downdrafts that flush relatively cool and dry (lower equivalent potential temperature, ?e) air into the storm's inflow layer. These previous results have been based on idealised numerical experiments for which we have deliberately chosen a simple set of physical parameterisations. Before efforts are undertaken to test the proposed framework with real atmospheric data, we assess here the robustness of our previous results in a more realistic and representative experimental setup by surveying and diagnosing five additional numerical experiments. The modifications of the experimental setup comprise the values of the exchange coefficients of surface heat and momentum fluxes, the inclusion of experiments with ice microphysics, and the consideration of weaker, but still mature tropical cyclones. In all experiments, the depression of the inflow layer ?e values is significant and all tropical cyclones exhibit the same general structural changes when interacting with the imposed vertical wind shear. Tropical cyclones in which strong downdrafts occur more frequently exhibit a more pronounced depression of inflow layer ?e outside of the eyewall in our experiments. The magnitude of the ?e depression underneath the eyewall early after shear is imposed in our experiments correlates well with the magnitude of the ensuing weakening of the respective tropical cyclone. Based on the evidence presented, it is concluded that the newly proposed framework is a robust description of intensity modification in our suite of experiments.

  7. Further examination of the thermodynamic modification of the inflow layer of tropical cyclones by vertical wind shear

    NASA Astrophysics Data System (ADS)

    Riemer, M.; Montgomery, M. T.; Nicholls, M. E.

    2012-03-01

    Recent work has developed a new framework for the impact of vertical wind shear on the intensity evolution of tropical cyclones. A focus of this framework is on the frustration of the tropical cyclone's power machine by shear-induced, persistent downdrafts that flush relatively cool and dry (lower equivalent potential temperature, ?e) air into the storm's inflow layer. These previous results have been based on idealised numerical experiments for which we have deliberately chosen a simple set of physical parameterisations. Before efforts are undertaken to test the proposed framework with real atmospheric data, we here survey and diagnose five additional numerical experiments with some modifications of the experimental setup to assess the robustness of our previous results. The modifications comprise the values of the exchange coefficients of surface heat and momentum fluxes, the inclusion of experiments with ice microphysics, and the consideration of weaker, but still mature tropical cyclones. In all experiments, the depression of the inflow layer ?e values is significant and all tropical cyclones exhibit the same general structural changes when interacting with the imposed vertical wind shear. Tropical cyclones with a higher downdraft activity exhibit a more pronounced depression of inflow layer ?e outside of the eyewall in our experiments. The magnitude of the ?e depression underneath the eyewall early after shear is imposed in our experiments correlates well with the magnitude of the ensuing weakening of the respective tropical cyclone. Based on the evidence presented, it is concluded that the newly proposed framework is a robust description of intensity modification in our suite of experiments.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

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

    PubMed

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

    2012-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

    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.

  13. The role of diabatic heating, torques and stabilities in forcing the radial-vertical circulation within cyclones part ii: case study of extratropical and tropical cyclones

    NASA Astrophysics Data System (ADS)

    Yuan, Zhuojian; Johnson, Donald R.

    1998-12-01

    Utilizing Eliassen's concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied through numerical simulations based on the linear diagnostic equation derived previously. The structure of the forcing associated with diabatic heating and torques was determined from quasi-Lagrangian diagnostic analyses of actual case studies. The two cyclones studied were the Ohio extratropical cyclone of 25-27 January 1978 and typhoon Nancy of 18-23 September 1979. The Ohio cyclone, which formed over the Gulf Coast and moved through Ohio and eastern Michigan, was one of the most intense storms with blizzard conditions to ever occur in this region. Typhoon Nancy which occurred over the South China Sea during the FGGE year was selected since relatively high quality assimilated data were available. Within the Ohio cyclone, the dominant internal processes forcing the mean circulation with embedded relatively strong hydrodynamic stability were the pressure torque associated with baroclinic (asymmetric) structure and the horizontal eddy angular momentum transport associated with the typical S-shaped thermal and wind structures of self-development. Within typhoon Nancy, the dominant internal process forcing the mean circulation with embedded weak hydrodynamic stability was the latent heat release. This analysis shows that the simulated azimuthally-averaged mass-weighted radial motions within these two cyclones agree quite well with the “ observed? azimuthally-averaged mass-weighted radial motions. This isentropic numerical study also provides insight into the relatively important internal forcing processes and the trade off between forcing and stability within both extratropical and tropical cyclones.

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

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Ocean acidification is the global decline in seawater pH and calcium carbonate (CaCO3) saturation state (?) 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    SciTech Connect

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

    2013-07-16

    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.

  19. Impacts and Recovery from Severe Tropical Cyclone Yasi on the Great Barrier Reef

    PubMed Central

    Beeden, Roger; Maynard, Jeffrey; Puotinen, Marjetta; Marshall, Paul; Dryden, Jen; Goldberg, Jeremy; Williams, Gareth

    2015-01-01

    Full recovery of coral reefs from tropical cyclone (TC) damage can take decades, making cyclones a major driver of habitat condition where they occur regularly. Since 1985, 44 TCs generated gale force winds (?17 metres/second) within the Great Barrier Reef Marine Park (GBRMP). Of the hurricane strength TCs (?H1—Saffir Simpson scale; ? category 3 Australian scale), TC Yasi (February, 2011) was the largest. In the weeks after TC Yasi crossed the GBRMP, participating researchers, managers and rangers assessed the extent and severity of reef damage via 841 Reef Health and Impact Surveys at 70 reefs. Records were scaled into five damage levels representing increasingly widespread colony-level damage (1, 2, 3) and reef structural damage (4, 5). Average damage severity was significantly affected by direction (north vs south of the cyclone track), reef shelf position (mid-shelf vs outer-shelf) and habitat type. More outer-shelf reefs suffered structural damage than mid-shelf reefs within 150 km of the track. Structural damage spanned a greater latitudinal range for mid-shelf reefs than outer-shelf reefs (400 vs 300 km). Structural damage was patchily distributed at all distances, but more so as distance from the track increased. Damage extended much further from the track than during other recent intense cyclones that had smaller circulation sizes. Just over 15% (3,834 km2) of the total reef area of the GBRMP is estimated to have sustained some level of coral damage, with ~4% (949 km2) sustaining a degree of structural damage. TC Yasi likely caused the greatest loss of coral cover on the GBR in a 24-hour period since 1985. Severely impacted reefs have started to recover; coral cover increased an average of 4% between 2011 and 2013 at re-surveyed reefs. The in situ assessment of impacts described here is the largest in scale ever conducted on the Great Barrier Reef following a reef health disturbance. PMID:25874718

  20. Impacts and recovery from severe tropical cyclone Yasi on the Great Barrier Reef.

    PubMed

    Beeden, Roger; Maynard, Jeffrey; Puotinen, Marjetta; Marshall, Paul; Dryden, Jen; Goldberg, Jeremy; Williams, Gareth

    2015-01-01

    Full recovery of coral reefs from tropical cyclone (TC) damage can take decades, making cyclones a major driver of habitat condition where they occur regularly. Since 1985, 44 TCs generated gale force winds (?17 metres/second) within the Great Barrier Reef Marine Park (GBRMP). Of the hurricane strength TCs (?H1-Saffir Simpson scale; ? category 3 Australian scale), TC Yasi (February, 2011) was the largest. In the weeks after TC Yasi crossed the GBRMP, participating researchers, managers and rangers assessed the extent and severity of reef damage via 841 Reef Health and Impact Surveys at 70 reefs. Records were scaled into five damage levels representing increasingly widespread colony-level damage (1, 2, 3) and reef structural damage (4, 5). Average damage severity was significantly affected by direction (north vs south of the cyclone track), reef shelf position (mid-shelf vs outer-shelf) and habitat type. More outer-shelf reefs suffered structural damage than mid-shelf reefs within 150 km of the track. Structural damage spanned a greater latitudinal range for mid-shelf reefs than outer-shelf reefs (400 vs 300 km). Structural damage was patchily distributed at all distances, but more so as distance from the track increased. Damage extended much further from the track than during other recent intense cyclones that had smaller circulation sizes. Just over 15% (3,834 km2) of the total reef area of the GBRMP is estimated to have sustained some level of coral damage, with ~4% (949 km2) sustaining a degree of structural damage. TC Yasi likely caused the greatest loss of coral cover on the GBR in a 24-hour period since 1985. Severely impacted reefs have started to recover; coral cover increased an average of 4% between 2011 and 2013 at re-surveyed reefs. The in situ assessment of impacts described here is the largest in scale ever conducted on the Great Barrier Reef following a reef health disturbance. PMID:25874718

  1. Effect of tropical cyclone intensity and instability on the evolution of spiral bands

    NASA Astrophysics Data System (ADS)

    Huang, Hong; Jiang, Yongqiang; Chen, Zhongyi; Luo, Jian; Wang, Xuezhong

    2014-09-01

    The evolution of spiral-band-like structures triggered by asymmetric heating in three tropical-cyclone-like vortices of different intensities is examined using the Three-Dimensional Vortex Perturbation Analyzer and Simulator (3DVPAS) model. To simulate the spiral bands, asymmetric thermal perturbations are imposed on the radius of maximum wind (RMW) of vortices, which can be considered as the location near the eyewall of real tropical cyclones (TCs). All the three vortices experience a hydrostatic adjustment after the introduction of thermal asymmetries. It takes more time for weaker and stable vortices to finish such a process. The spiral-band-like structures, especially those distant from the vortex centers, form and evolve accompanying this process. In the quasi-balance state, the spiral bands are gradually concentrated to the inner core, the wave behavior of which resembles the features of classic vortex Rossby (VR) waves. The unstable vortices regain nonhydrostatic features after the quasi-balance stage. The spiral bands further from the vortex center, similar to distant spiral bands in real TCs, form and maintain more easily in the moderate basic-state vortex, satisfying the conditions of barotropic instability. The widest radial extent and longest-lived distant bands always exist in weak and stable vortices. This study represents an attempt to determine the role of TC intensity and stability in the formation and evolution of spiral bands via hydrostatic balance adjustment, and provides some valuable insights into the formation of distant spiral rainbands.

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

    SciTech Connect

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

    2012-06-01

    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."

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

    SciTech Connect

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

    2013-10-19

    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 resented as powerful tools that distill complex datasets into concise statements on likely impact, and as highly effective communication devices.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2010-01-01

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

  5. Objective Operational Utilization of Satellite Microwave Scatterometer Observations of Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Cardone, Vincent J.; Cox, Andrew T.

    2000-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Li, Qingqing; Duan, Yihong

    2010-06-01

    The spatiotemporal features of tropical cyclone strikes from 1949 to 2008 at 49 coastal cities of China are investigated in this study. The cities in Hainan, Guangdong, and Taiwan have high strike frequencies, with the severest and most frequent average strikes found in Taiwan. In Hainan, strike clusters appear in the mid-1950s, the early 1960s and 1970s, and the late 1980s, with relative inactive frequencies from the mid-1990s to 2008, and the clusters of strikes in Guangdong are found during the 1970s. In Taiwan, the most active strikes are found during the period 1956-1963. The return periods for all typhoons are either 1 or 2 years at the coastal cities of Taiwan in contrast to 2-5 and 4-8 years at the cities of Guangdong and Fujian, respectively. Super typhoons affect Taiwan with a frequency of once every 12-30 years on average. A tropical cyclone hazard index is also created to investigate the vulnerability at these cities.

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

    NASA Astrophysics Data System (ADS)

    McGrath, Gavan S.; Sadler, Rohan; Fleming, Kevin; Tregoning, Paul; Hinz, Christoph; Veneklaas, Erik J.

    2012-02-01

    The Big Dry, a recent drought over southeast Australia, began around 1997 and continued until 2011. We show that between 2002-2010, instead of a localized drought, there was a continent-wide reduction in water storage, vegetation and rainfall, spanning the northwest to the southeast of Australia. Trends in water storage and vegetation were assessed using Gravity Recovery and Climate Experiment (GRACE) and Normalized Difference Vegetation Index (NDVI) data. Water storage and NDVI are shown to be significantly correlated across the continent and the greatest losses of water storage occurred over northwest Australia. The frequency of tropical cyclones over northwest Australia peaked just prior to the launch of the GRACE mission in 2002. Indeed, since 1981, decade-scale fluctuations in tropical cyclone numbers coincide with similar variation in rainfall and vegetation over northwest Australia. Rainfall and vegetation in southeast Australia trended oppositely to the northwest prior to 2001. Despite differences between the northwest and southeast droughts, there is reason to believe that continental droughts may occur when the respective climate drivers align.

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

    NASA Astrophysics Data System (ADS)

    Griffin, K.; Bosart, L. F.

    2012-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Slocum, Christopher J.

    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.

  12. Investigation into impact of tropical cyclones on the ionosphere using GPS sounding and NCEP/NCAR Reanalysis data

    NASA Astrophysics Data System (ADS)

    Polyakova, Anna; Perevalova, Natalia

    Spatial-temporal dynamics of Total Electron Content (TEC) disturbances over zones with higher cyclonic activity was investigated. The TEC data from the international network of two-frequency ground-based GPS receivers were used. An increase in intensity of wave TEC disturbances in two period ranges (2-20 min and 15-40 min) was registered under quiet geo-magnetic conditions during several tropical cyclones. We mapped the TEC variation intensity for strong tropical cyclones observed over the Northwest Atlantic Ocean in August-November 2005. It is shown that analysis of spatial distribution of ionospheric disturbances using TEC variation maps allows us to select disturbances most probably associated with cyclones. Com-parative analysis of TEC variations with changes in meteorological parameters was made. For this purpose we used the NCEP Reanalysis data provided by NOAA/OAR/ESRL PSD, Boul-der, Colorado, USA, from their website at http://www.esrl.noaa.gov/psd/. We also estimated influence of the wind atmospheric regime on appearance of ionospheric disturbances generated by tropical cyclones. This work was supported by the Russian Foundation for Basic Research (grant 08-05-00658).

  13. Analysis of tropical cyclone dynamics in a conceptual box-model and the axisymmetric cloud model HURMOD

    NASA Astrophysics Data System (ADS)

    Schönemann, D.; Frisius, T.

    2010-09-01

    Tropical cyclone dynamics is investigated by means of a low order box-model and an axisymmetric high-resolution cloud model. Within the conceptual model the tropical cyclone is divided into three regions, namely the eye, the eyewall and the ambient region. It comprises the processes of surface evaporation, radial entropy advection, convection and radiative cooling. For typical tropical ocean parameter settings the system possesses three steady state solutions when the sea surface temperature (SST) is above a critical minimum value. One steady state is unstable while the two remaining states are stable. One of the stable solutions represents the atmosphere at rest and the other can be identified as a tropical cyclone at its maximum potential intensity (MPI). A saddle node bifurcation appears at a critical minimum temperature where two branches vanish. Below the critical temperature, only the atmosphere at rest represents a steady state solution in the system. A bifurcation diagram provides an explanation why only finite-amplitude perturbations above a critical SST can transform into tropical cyclones. Besides SST, relative humidity of the ambient region forms an important model parameter and the surfaces that describe equilibria as a function of SST and relative humidity reveal a cusp-catastrophe where the two non-trivial equilibria split up into four. Within the model regime of four equilibria, cyclogenesis becomes very unlikely due to the repulsing and attracting effects of the two additional equilibria. The results are in qualitative agreement with observations. Furthermore it is tested, whether the qualitative behaviour observed in the box-model simulations is reproducible in the axisymmetric cloud model HURMOD. It is shown that an attractor associated with a tropical cyclone exists in HURMOD when a simplified cloud physics is applied, so that condensate terminates immediately. By varying SST 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 the simple model approach to the dynamics of tropical cyclone formation and its maximum potential intensity (MPI).

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. The Interdecadal Variability of Tropical Cyclone Intensification Rate in the North Western Pacific

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chen, C.

    2011-12-01

    The tropical cyclone (TC) intensification rate, including tropical depression stage, during 1945 to 2009 is analyzed using Joint Typhoon Warning Center (JTWC) best track data. The area of interest is divided into many 4x4-degree boxes, and the boxes in which the intensification rate is 2.5 knots/6hrs or more are defined as a hot zone. The spatial pattern and temporal variability of the hot zone are discussed. On monthly time scale, the hot zone extends northeastward starting from June and retreats southwestward after September. The spatial pattern of the hot zone shows a phase change around 1977, coincident with Pacific Decadal Oscillation (PDO). Therefore, the correlation between intensification rate, smoothed by 21-year running mean, of each 4x4-degree box and the PDO index is computed. The result shows an area with highly positive correlation (>= 0.8) stretching from southeast ocean of Japan via Ryukyu Islands, Taiwan, coastal regions of Guangdong, Hainan Island to coastal regions of Vietnam, and an area with highly negative correlation (<=-0.8) over Philippine Sea. This correlation map indicates that during the PDO warm phase, the low latitude hot zone tends to be smaller, and the weakening of TCs over higher latitudes becomes less significant as well. In other words, the TC intensity tends to change less during the PDO warm phase on average. PDO has the most significant signal on sea surface temperature anomaly (SSTA) in the north central Pacific with its secondary signal in the tropics. However, our preliminary result shows that the most possible mechanism for PDO to influence TC development in the North Western Pacific is through the large-scale atmospheric circulation, rather SSTA in the tropics. When comparing the 850 hPa flow of the PDO warm phase with that of PDO cold phase, an anti-cyclonic anomaly appears in the vicinity of Philippine. Accompany with this anti-cyclonic anomaly is weaker low level vorticity and weaker high level divergence, all are not favorable for TC intensification during the PDO warm phase.

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

    NASA Astrophysics Data System (ADS)

    Abdullah, Warith; Reddy, Remata

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

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

    NASA Astrophysics Data System (ADS)

    Wu, Liang; Huang, Ronghui; Wen, Zhiping

    2014-05-01

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

  19. Possible relationship between East Asian summer monsoon and western North Pacific tropical cyclone genesis frequency

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    In the present study, the fact that strong positive correlations have existed between East Asian summer monsoons (EASMs) and western North Pacific tropical cyclone (TC) genesis frequency over the last 37 years was found. To figure out the cause of these correlations, 7 years (positive East Asian summer monsoon index (EASMI) phase) that have the highest values and 7 years (negative EASMI phase) that have the lowest values in the normalized EASM index were selected and the differences in averages between the two phases were analyzed. In the positive EASMI phase, TCs mainly occurred in the northwestern waters of the tropical and subtropical western North Pacific and showed a tendency to move from the far eastern waters of the Philippines, pass the East China Sea, and move northward toward Korea and Japan. On the 500 hPa streamline, whereas anomalous anticyclones developed in the East Asia middle-latitude region, anomalous cyclones developed in the tropical and subtropical western North Pacific. Therefore, in this phase, whereas EASMs were weakened, western North Pacific summer monsoons (WNPSMs) were strengthened so that some more TCs could occur. In addition, in the case of the East China Sea and the southern waters of Japan located between the two anomalous pressure systems, TCs could move some more toward the East Asia middle-latitude region in this phase. According to an analysis of the 850 hPa relative vorticity, negative anomalies were strengthened in the East Asia middle-latitude region while positive anomalies were strengthened in the region south to 25 N. Therefore, in the positive EASMI phase, whereas EASMs were weakened, WNPSMs were strengthened so that some more TCs could occur. According to an analysis of the 850 and 200 hPa horizontal divergence, whereas anomalous downward flows were strengthened in the East Asia middle-latitude region, anomalous upward flows were strengthened in the tropical and subtropical western North Pacific. According to an analysis of 200-850 hPa vertical wind shear and 600 hPa relative humidity, negative anomalies and positive anomalies were strengthened in the tropical and subtropical western North Pacific, respectively, to provide good atmospheric environments in which some more TCs could occur in the positive EASMI phase. According to an analysis of sea surface temperatures (SST) too, whereas cold SST anomalies were strengthened in the East Asia middle-latitude region, warm SST anomalies were strengthened in the tropical and subtropical western North Pacific to provide good marine environments in which some more TCs could occur in the positive EASMI phase.

  20. Sjune 2007State of the Climate in 2006 | attributable in part to the lack of tropical cyclones

    E-print Network

    Yu, Lisan

    of the continent. Clas- sical ENSO teleconnections, as well as modulation by the MJO, were observed. · Asia of Australia were the warmest on record. Many locations were impacted by severe drought and tropical cyclones and the atmosphere did not materialize fully and no dis- cernable ENSO signature was evident in the precipi- tation

  1. Effects of Relative and Absolute Sea Surface Temperature on Tropical Cyclone Potential Intensity Using a Single-Column Model

    E-print Network

    Sobel, Adam

    Effects of Relative and Absolute Sea Surface Temperature on Tropical Cyclone Potential Intensity, in final form 1 July 2010) ABSTRACT The effects of relative and absolute sea surface temperature (SST) single-column model. The model is run in two modes: (i) radiative­convective equilibrium (RCE

  2. Impact of the Tropopause Temperature on the Intensity of Tropical Cyclones: An Idealized Study Using a Mesoscale Model

    E-print Network

    Sobel, Adam

    Impact of the Tropopause Temperature on the Intensity of Tropical Cyclones: An Idealized Study, in final form 10 July 2014) ABSTRACT This study investigates the impact of the tropopause temperature surface temperature and an isothermal stratosphere with constant tropopause temperature. The potential

  3. The Gradient Velocity Track Display (GrVTD) Technique for Retrieving Tropical Cyclone Primary Circulation from Aliased Velocities Measured

    E-print Network

    Xue, Ming

    The Gradient Velocity Track Display (GrVTD) Technique for Retrieving Tropical Cyclone Primary Circulation from Aliased Velocities Measured by Single-Doppler Radar MINGJUN WANG Key Laboratory for Mesoscale December 2011, in final form 22 February 2012) ABSTRACT The ground-based velocity track display (GBVTD

  4. An analysis of long-term relationships among count statistics and metrics of synthetic tropical cyclones downscaled from CMIP5 models

    NASA Astrophysics Data System (ADS)

    Reed, Andra J.; Mann, Michael E.; Emanuel, Kerry A.; Titley, David W.

    2015-08-01

    In a changing climate, the impact of tropical cyclones on the United States Atlantic and Gulf Coasts will be affected both by how intense and how frequent these storms become. The observational record of tropical cyclones in the Atlantic Basin is too short (A.D. 1851 to present) to allow for accurate assessment of low-frequency variability in storm activity. In order to overcome the limitations of the short observational record, we downscale four Coupled Model Intercomparison Project Phase 5 models to generate synthetic tropical cyclone data sets for the Atlantic Basin that span the interval of A.D. 850-2005. Using these long-term synthetic tropical cyclone data sets, we investigate the relationship between power dissipation and ocean temperature metrics, as well as the relationship between basin-wide and landfalling tropical cyclone count statistics over the past millennium. Contrary to previous studies, we find only a very weak relationship between power dissipation and main development region sea surface temperature in the Atlantic Basin. Consistent with previous studies, we find that basin-wide and landfalling tropical cyclone counts are significantly correlated with one another, lending further support for the use of paleohurricane landfall records to infer long-term basin-wide tropical cyclone trends.

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

    NASA Astrophysics Data System (ADS)

    Antinao, J.; Farfan, L.

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  7. Extreme Rainfall Intensities and Long-term Rainfall Risk from Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Langousis, A.; Veneziano, D.

    2009-04-01

    We develop a methodology to estimate the rate of extreme rainfalls at coastal sites due to tropical cyclones (TCs). A basic component of the methodology is the probability distribution of ID,max, the maximum rainfall intensity at the site over a period D during the passage of a TC with given characteristics Î&.cedil; The long-term rainfall risk is obtained by combining the conditional distribution of (ID,max|Î&)cedil; with a recurrence model for Î&.cedil; The lack of extensive TC rainfall records and the many parameters needed to characterize the motion, size and intensity of tropical cyclones make it difficult to estimate the distribution of (ID,max|Î&)cedil; directly from data. Hence, we have resorted to a combination of physical modeling to obtain the mean rainfall field for a TC with given characteristics Î&,cedil; and statistical analysis to include storm-to-storm variability, as well as intra-storm rainfall fluctuations due to rainbands and local convection. The vector Î& cedil;includes the maximum tangential wind velocity V max, the radius of maximum winds Rmax and the translation speed V t of the storm, in addition to the distance y of the coastal site from the TC center. The physical model of TC rainfall uses an extension of Smith's (1968) boundary layer (BL) formulation and simple moist air thermodynamics to calculate the vertical outflow of water vapor from the top of the TC boundary layer, which is assumed to be all converted into rainfall. However, the calculated rainfall field is not simply proportional to the vertical flux of moisture. This is because (1) the trajectory of moisted air parcels has an outward slant depending on distance from the TC center and (2) the ascending air parcels and descending rain drops are advected into a helical motion by the cyclonic circulation; therefore a parcel of air that leaves the TC boundary layer contributes rainfall to a range of azimuthal locations. The statistical component of the model characterizes the distribution of (ID,max|Î&)cedil; by comparing the physical model results with precipitation radar (PR) data from the TRMM mission. Taylor's hypothesis is used to convert spatial rainfall intensity fluctuations to temporal fluctuations at a given location A. To illustrate the use of the model for long-term rainfall risk analysis, we formulate a recurrence model for tropical cyclones in the Gulf of Mexico that make landfall between longitudes 85o-95oW and compare the intensity-duration-frequency (IDF) curves for New Orleans obtained by the present model with similar curves in the literature based on continuous rainfall records. The latter include all types of rainstorms. We find that for return periods of 100 years or more and long averaging durations (D around 12-24 hours), tropical cyclones dominate over other rainfall event types, whereas the reverse is true for shorter return periods or shorter averaging durations. We also determine how the most likely TC scenario varies with the averaging duration D and the return period T . We do so by plotting the modal values of V max, Rmax, and V t conditioned on exceeding the T -yr rainfall intensity for duration D. The mode of V t decreases as T increases, because more intense rainfalls are generally produced by slower-moving systems. The mode of Rmax decreases when D or T increase, whereas the opposite is true for V max. For the distance y from the TC center, the modal value is always close to Rmax, the location where maximum rainfall intensities tend to occur. These modal values can be used to define T -year scenario events.

  8. Using Mixture Regression to Understand and Model Tropical Cyclone Intensification in Relation to the Environment and Climate

    NASA Astrophysics Data System (ADS)

    Yonekura, E.; Lin, N.; Wang, Y.; Fan, J.

    2014-12-01

    Representing the relationship between tropical cyclone intensity and the surrounding environment is key to projecting the way tropical cyclones change with the climate. However, capturing the complex relationship between tropical cyclone intensification, the surrounding environment, and storm characteristics may not be possible with simple linear regression models like SHIPS, especially for short forecast periods in risk models. Here, we move beyond simple linear modeling and apply methods that perform variable selection, determine if the data is a heterogeneous "mixture" of multiple features, and fit linear or nonlinear functions of predictors for a 6-hour forecast window. We also incorporate a new predictor, the Ventilation Index, which represents the surrounding environmental conditions in a way that is known to affect tropical cyclone intensity according to hurricane physics. The data used to construct the models comes from the IBTrACS WMO archive for TC-specific data and ERSST v3b and the NCEP-NCAR Reanalysis for environmental variables from 1970-2010 in the North Atlantic. The two observed measures of intensity, the maximum sustained wind speed and minimum central pressure, are modeled jointly. First, we find that variable selection in both linear and nonlinear models does not significantly reduce the number of environmental predictors needed or improve the model R-squared. Second, mixture regression is applied to establish data groupings and their associated predictors. There is an increase in R-squared by 0.10 compared to the linear regression model that uses all possible variables as predictors. The number of environmental predictors decreases from 8 to 4 for wind intensification and to 2 for pressure intensification. When we further restrict the predictor pool to use only Ventilation Index to represent the environment, mixture modeling shows a 0.10 increase in R-squared. Then, allowing nonlinear relationships with predictors in a mixture model with Ventilation Index gives a further R-squared increase of 0.20. We show that mixture modeling is the best approach to create a climate-variant model for tropical cyclone intensity that can be used as part of a tropical cyclone risk model. The techniques may also be applied to other aspects of tropical cyclones, such as storm genesis and size.

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

    SciTech Connect

    Lackmann, Gary

    2013-06-10

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

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

    NASA Astrophysics Data System (ADS)

    Lee, Marguerite; Frisius, Thomas

    2015-04-01

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

  11. A validation study for GPS radio occultation data with moist thermodynamic structure of tropical cyclones

    NASA Astrophysics Data System (ADS)

    Vergados, Panagiotis; Mannucci, Anthony J.; Su, Hui

    2013-08-01

    We exploit the cloud-penetrating capability and insensitivity to precipitation of the Global Positioning System radio occultation (GPSRO) technique to study the humidity environment of tropical cyclones (TCs). We focus in regions within and around the vicinity of TCs' eye, where infrared and microwave observations are difficult to acquire due to cloudiness and heavy precipitation. We use data from the National Hurricane Center TC Best Tracks to identify the location of North Atlantic TCs. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Data Analysis and Archive Center provides concurrent refractivity, temperature, and humidity measurements from the Challenging Minisatellite Payload and COSMIC missions and the European Centre for Medium-Range Weather Forecasts (ECMWF). The distribution of GPSRO-derived humidity profiles as functions of altitude and distance from the storms' center identifies a pronounced low-level inflow, characteristic of mature TCs, at distances between 50 and 90 km, which coincide with the area where the eyewall of TCs forms. We also capture wavelike structures resembling spiral rainbands beyond the eyewall. The distribution of water vapor as functions of altitude and TC intensity shows a decrease at all altitudes when a tropical system matures from a tropical depression to a Category 1 (Cat 1) hurricane. The water vapor gradually increases from Cat 2 to Cat 5 hurricanes—a result that is also identified in ECMWF data sets and Atmospheric Infrared Sounder observations. We conclude that GPSRO data can contribute significantly to the understanding and modeling of the vertical structures of TCs.

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

    NASA Astrophysics Data System (ADS)

    Scott, C. A.; Farfan, L.

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  14. Effects of thermodynamic profiles on the interaction of binary tropical cyclones

    NASA Astrophysics Data System (ADS)

    Jang, Wook; Chun, Hye-Yeong

    2015-09-01

    The interactions between idealized binary tropical cyclones (TCs) on f and ? planes with different separation distance and thermodynamic soundings obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data averaged over the western North Pacific are investigated through ensemble three-dimensional numerical simulations with a horizontal resolution of 10 km in a single domain. In the simulations on the f plane, two TCs show mutual cyclonic rotations with symmetric structures. Two TCs with thermodynamic profiles of larger convective available potential energy (CAPE) and maximum potential intensity (MPI) show greater interaction than those with a smaller CAPE and MPI due to the stronger tangential velocity near the TC center. In the simulations on the ? plane, the two TCs do not merge, because the beta effect prevents the attraction of the two TCs by generating asymmetric motions of the TC with northwestward forcing. The relative strengths of the two TCs change with time and depend on the low-level inflow influenced by the Coriolis parameter. Similar to the results on the f plane, the two TCs only merge with the thermodynamic soundings of large CAPE and MPI.

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

    NASA Astrophysics Data System (ADS)

    Belanger, James Ian

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

  16. Characteristics of Tropical Cyclones in High-Resolution Models of the Present Climate

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hall, T. M.

    2009-12-01

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

  19. Sensitivity of quasi-periodic outer rainband activity of tropical cyclones to the surface entropy flux

    NASA Astrophysics Data System (ADS)

    Li, Qingqing; Duan, Yihong

    2013-10-01

    The influence of outer-core surface entropy fluxes (SEFs) on tropical cyclone (TC) outer rainband activity is investigated in this study with a fully compressible, nonhydrostatic model. A control simulation and two sensitivity experiments with the outer-core SEF artificially increased and decreased by 20% respectively were conducted to examine the quasi-periodic outer rainband behavior. Larger negative horizontal advection due to the greater radial wind and the positive contribution by asymmetric eddies leads to a longer period of outerrainband activity in the SEF-enhanced experiment. The well-developed outer rainbands in the control and SEF-reduced simulations significantly limit the TC intensity, whereas such an intensity suppression influence is not pronounced in the SEF-enhanced experiment. As diabatic heating in outer rainbands strengthens the outer-core tangential wind, the quasi-periodic activity of outer rainbands contributes to the quasi-periodic variations of the inner-core size of the TCs.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Zhang, Gan; Wang, Zhuo

    2015-04-01

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

  2. A new approach to using wind speed for prediction of tropical cyclone generated storm surge

    NASA Astrophysics Data System (ADS)

    Jordan, Mark R.; Clayson, Carol Anne

    2008-07-01

    We examine the best track wind speed data for all U.S. landfalling hurricanes between 1986 and 2007 to determine the relationship between wind speed and observed maximum storm surge heights at the coast. We show that pre-landfall intensity correlates significantly better with observed maximum surge heights than landfall intensity does. This outcome is not a result of outliers skewing the data, but is representative of a more definitive trend. We anticipate that our findings will lead to a reconsideration of the way wind is used as a surge predictor, and we believe that our findings provide a possible explanation for why some tropical cyclones' storm surges tend to over/under perform with respect to official storm surge forecasts.

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

    E-print Network

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

    2014-01-01

    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.

  4. Characteristics of tropical cyclones in high-resolution models in the present climate

    SciTech Connect

    Shaevitz, Daniel A.; Camargo, Suzana J.; Sobel, Adam H.; Jonas, Jeffrey A.; Kim, Daehyun; Kumar, Arun; Lim, Young -Kwon; Reed, Kevin A.; Roberts, Malcolm J.; Scoccimarro, Enrico; Vidale, Pier Luigi; Wang, Hui; Zhao, Ming; Henderson, Naomi

    2014-12-05

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

  5. Dynamic Potential Intensity: An improved representation of the ocean's impact on tropical cyclones

    NASA Astrophysics Data System (ADS)

    Balaguru, Karthik; Foltz, Gregory R.; Leung, L. Ruby; Asaro, Eric D'; Emanuel, Kerry A.; Liu, Hailong; Zedler, Sarah E.

    2015-08-01

    To incorporate the effects of tropical cyclone (TC)-induced upper ocean mixing and sea surface temperature (SST) cooling on TC intensification, a vertical average of temperature down to a fixed depth was proposed as a replacement for SST within the framework of air-sea coupled Potential Intensity (PI). However, the depth to which TC-induced mixing penetrates may vary substantially with ocean stratification and storm state. To account for these effects, here we develop a "Dynamic Potential Intensity" (DPI) based on considerations of stratified fluid turbulence. For the Argo period 2004-2013 and the three major TC basins of the Northern Hemisphere, we show that the DPI explains 11-32% of the variance in TC intensification, compared to 0-16% using previous methods. The improvement obtained using the DPI is particularly large in the eastern Pacific where the thermocline is shallow and ocean stratification effects are strong.

  6. Right-side cooling and phytoplankton bloom in the wake of a tropical cyclone

    NASA Astrophysics Data System (ADS)

    Huang, S.-M.; Oey, Lie-Yauw

    2015-08-01

    The rightward tendency (in northern hemisphere) of enhanced phytoplankton bloom often observed in the wake of a tropical cyclone has commonly been attributed to the rightward bias of mixing due to stronger wind and wind-current resonance. We demonstrated using a high-resolution biophysical model that vertical mixing alone resulted only in weak asymmetry after the passage of the storm. The enhanced bloom was caused instead by decreased turbulence due to restratification by submesoscale recirculation cells preferentially produced on the right side, rightward shift of cool isotherms, and spin-up of a subsurface jet. We showed using a two-time scale asymptotic expansion that these slower-evolving features were forced by resonance Reynolds stresses of the energetic and rapidly oscillating near-inertial internal waves.

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

    SciTech Connect

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

    2014-05-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.

    2015-04-01

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

  11. Characteristics of tropical cyclones in high-resolution models in the present climate

    DOE PAGESBeta

    Shaevitz, Daniel A.; Camargo, Suzana J.; Sobel, Adam H.; Jonas, Jeffrey A.; Kim, Daehyun; Kumar, Arun; LaRow, Timothy E.; Lim, Young -Kwon; Murakami, Hiroyuki; Reed, Kevin A.; et al

    2014-12-05

    The global characteristics of tropical cyclones (TCs) simulated by several climate models are analyzed and compared with observations. The global climate models were forced by the same sea surface temperature (SST) fields in two types of experiments, using climatological SST and interannually varying SST. TC tracks and intensities are derived from each model's output fields by the group who ran that model, using their own preferred tracking scheme; the study considers the combination of model and tracking scheme as a single modeling system, and compares the properties derived from the different systems. Overall, the observed geographic distribution of global TCmore »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.« less

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

    PubMed Central

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

    2015-01-01

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

  13. Characteristics of Tropical Cyclones in High-Resolution Models in the Present Climate

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  14. Environmental modeling, technology, and communication for land falling tropical cyclone/hurricane prediction.

    PubMed

    Tuluri, Francis; Reddy, R Suseela; Anjaneyulu, Y; Colonias, John; Tchounwou, Paul

    2010-05-01

    Katrina (a tropical cyclone/hurricane) began to strengthen reaching a Category 5 storm on 28th August, 2005 and its winds reached peak intensity of 175 mph and pressure levels as low as 902 mb. Katrina eventually weakened to a category 3 storm and made a landfall in Plaquemines Parish, Louisiana, Gulf of Mexico, south of Buras on 29th August 2005. We investigate the time series intensity change of the hurricane Katrina using environmental modeling and technology tools to develop an early and advanced warning and prediction system. Environmental Mesoscale Model (Weather Research Forecast, WRF) simulations are used for prediction of intensity change and track of the hurricane Katrina. The model is run on a doubly nested domain centered over the central Gulf of Mexico, with grid spacing of 90 km and 30 km for 6 h periods, from August 28th to August 30th. The model results are in good agreement with the observations suggesting that the model is capable of simulating the surface features, intensity change and track and precipitation associated with hurricane Katrina. We computed the maximum vertical velocities (W(max)) using Convective Available Kinetic Energy (CAPE) obtained at the equilibrium level (EL), from atmospheric soundings over the Gulf Coast stations during the hurricane land falling for the period August 21-30, 2005. The large vertical atmospheric motions associated with the land falling hurricane Katrina produced severe weather including thunderstorms and tornadoes 2-3 days before landfall. The environmental modeling simulations in combination with sounding data show that the tools may be used as an advanced prediction and communication system (APCS) for land falling tropical cyclones/hurricanes. PMID:20623002

  15. Development of a geovisual analytics environment using parallel coordinates with applications to tropical cyclone trend analysis

    NASA Astrophysics Data System (ADS)

    Steed, Chad Allen

    A global transformation is being fueled by unprecedented growth in the quality, quantity, and number of different parameters in environmental data through the convergence of several technological advances in data collection and modeling. Although these data hold great potential for helping us understand many complex and, in some cases, life-threatening environmental processes, our ability to generate such data is far outpacing our ability to analyze it. In particular, conventional environmental data analysis tools are inadequate for coping with the size and complexity of these data. As a result, users are forced to reduce the problem in order to adapt to the capabilities of the tools. To overcome these limitations, we must complement the power of computational methods with human knowledge, flexible thinking, imagination, and our capacity for insight by developing visual analysis tools that distill information into the actionable criteria needed for enhanced decision support. In light of said challenges, we have integrated automated statistical analysis capabilities with a highly interactive, multivariate visualization interface to produce a promising approach for visual environmental data analysis. By combining advanced interaction techniques such as dynamic axis scaling, conjunctive parallel coordinates, statistical indicators, and aerial perspective shading, we provide an enhanced variant of the classical parallel coordinates plot. Furthermore, the system facilitates statistical processes such as stepwise linear regression and correlation analysis to assist in the identification and quantification of the most significant predictors for a particular dependent variable. These capabilities are combined into a unique geovisual analytics system that is demonstrated via a pedagogical case study and three North Atlantic tropical cyclone climate studies using a systematic workflow. In addition to revealing several significant associations between environmental observations and tropical cyclone activity, this research corroborates the notion that enhanced parallel coordinates coupled with statistical analysis can be used for more effective knowledge discovery and confirmation in complex, real-world data sets.

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

    NASA Astrophysics Data System (ADS)

    Dou, Fangli; Yin, Honggang; Gu, Songyan

    2014-11-01

    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.

  17. Effects of tropical cyclone characteristics on the surface wave fields in the Australian North West region

    NASA Astrophysics Data System (ADS)

    Drost, Edwin; Lowe, Ryan; Péquignet, Christine; Ivey, Greg; Jones, Nicole

    2015-04-01

    The northwestern Australian coastline is subject to frequent extreme wave forcing resulting from tropical cyclones (TCs) during the summer months on Australia's North West Shelf (NWS). Compared to the northern hemisphere, knowledge about the wave climate, and TC generated waves in particular on the NWS is limited. TCs on the NWS show considerable variability in paths: some move predominantly parallel to the coastline, while others propagate in a coast-normal direction. It has been suggested that surface wave fields generated by coast-parallel moving TCs are different compared to TCs moving in a coast-normal direction across the shelf. In particular, wave heights generated by coast-parallel storms may be limited in size due to both refraction and bottom friction effects. First, this study evaluates the performance of a numerical wave model (SWAN) to hindcast the surface wave fields under different TC conditions forced by a parametric TC wind model of the region. Hindcast simulations were run for 4 case studies: the coast-parallel TCs Nicholas (2008) and Bianca (2011), and the coast-normal TCs Lua (2012) and Christine (2013). Model output was compared both temporally and spatially by in situ wave buoy data and satellite altimeter data and generally showed a good agreement for throughout the history of these TCs. However, for the more intense and larger system TC Lua, the model was found to overestimate the significant wave heights, especially in the left front quadrant of the storm. A modified SWAN model using adjusted wave energy dissipation terms was found to improve model output under these conditions. Second, output from the numerical simulations is used to analyse the mechanisms behind the generation and dissipation of the wave field and to relate them to tropical cyclone characteristics including the radius of maximum winds and the storm translation speed and direction.

  18. Cluster analysis of explicitly and downscaled simulated North Atlantic tropical cyclone tracks

    NASA Astrophysics Data System (ADS)

    Daloz, A.; Camargo, S. J.; Kossin, J. P.; Emanuel, K.

    2013-12-01

    The response of tropical cyclone (TC) activity to climate change is a question of major interest. In order to address this crucial issue, several types of models have been developed in the past, such as Global Climate Models (GCMs). However, the horizontal resolution of those models usually leads to some difficulties in resolving the inner core of TCs and then to properly simulate TC activity. In order to avoid this problem, an alternative tool has been developed by Emanuel (2005). This downscaling technique uses tracks that are initiated by randomly seeding large areas of the tropics with weak vortices. Then the survival of the tracks is based on large-scale environmental conditions produced by GCMs in our case. Here we compare the statistics of TC tracks simulated explicitly in four GCMs to the results of the downscaling technique driven by the four same GCMs in the present and future climates over the North Atlantic basin. Simulated tracks are objectively separated into four groups using a cluster technique (Kossin et al. 2010). The four clusters form zonal and meridional separations of tracks as shown in Figure 1. The meridional separation largely captures the separation between hybrid or baroclinic storms (clusters 1 and 2) and deep tropical systems (clusters 3 and 4), while the zonal separation segregates Gulf of Mexico and Cape Verde storms. Except for the seasonality, the downscaled simulations better capture the general characteristics of the clusters (mean duration of the tracks, intensity...) compared with the explicit simulations, which present strong biases. In the second part of this study, we use three different scenarios to examine the possible future changes of the clusters from the downscaled simulations. We explored the role of a warming of the SST, an increase in carbon dioxide and a combination of both ones. The results show that the response to each scenario is highly varying depending on the simulation examined. References - Kossin, J. P., S. J. Camargo, and M. Sitkowski, 2010: Climate modulation of North Atlantic hurricane tracks. Journal of Climate, 23, 3057-3076, DOI: 10.1175/2010JCLI3497.1. - Emanuel, K., 2005: Climate and Tropical Cyclone activity: A new downscaling approach. Journal of Climate, 19, 4797-4802.

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

    NASA Astrophysics Data System (ADS)

    Holdaway, Daniel

    2015-04-01

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

  20. Investigating Sensitivity to Saharan Dust in Tropical Cyclone Formation Using Nasa's Adjoint Model

    NASA Technical Reports Server (NTRS)

    Holdaway, Daniel

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Putman, William M.

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mardhekar, D.

    2010-09-01

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

  3. 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)

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

    2009-01-01

    Tropical cyclones in the northern Indian Ocean pose serious challenges to operational weather forecasting systems, partly due to their shorter lifespan and more erratic track, compared to those in the Atlantic and the Pacific. Moreover, the automated analyses of cyclones over the northern Indian Ocean, produced by operational global data assimilation systems (DASs), are generally of inferior quality than in other basins. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Tsai, Hsiao-Chung; Elsberry, Russell L.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  10. Diagnosis of tropical cyclone activity through gravity wave energy density in the southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ibrahim, C.; Chane-Ming, F.; Barthe, C.; Kuleshov, Y.

    2010-05-01

    Tropical cyclone (TC) activity is diagnosed through convective gravity waves (GWs) observed in the upper troposphere (UT)/lower stratosphere (LS) above Tromelin island (15.53°S, 54.31°E) in the tropical southwest Indian Ocean. Monthly and weekly GW total energy densities derived from daily GPS windsonde data are compared with Outgoing Longwave Radiation (OLR) and TC hours in the vicinity of Tromelin. A relationship between GW energy density and TC activity is observed in the LS, for the TC season 2001/2002. Moreover TCs (local convection) produce GWs with total energy density mostly higher (lower) than 12 J kg-1. A 10-season climatology (1997/1998-2006/2007) confirms that large values of GW total energy density in the LS are associated with weak values of OLR during the TC passage. Monthly total, kinetic and potential GW energy densities within 2000 km radius of Tromelin can be estimated using linear relationships with TC hours for a threshold of above 6 TC days per month. A linear relationship also exists between weekly GW total energy density in the LS and the activity of intense TCs above a threshold of 2 TC days per week within 1000 km radius of Tromelin. GW energy density in the LS could be used as a possible index to investigate TC activity in the UT/LS.

  11. The Sensitivity of Simulated Tropical Cyclones to Tunable Physical Parameters in Community Atmosphere Model

    NASA Astrophysics Data System (ADS)

    He, F.; Posselt, D. J.

    2014-12-01

    The inability to explicitly resolve the sub-grid scale physical processes (e.g. cloud, precipitation and convection) of atmospheric general circulation models (AGCMs) greatly limits their performance in simulating tropical cyclones (TCs) and predicting their future changes. To address it, this study carried out a total of 92 simulations and investigated the sensitivity of TC simulation to 24 physical parameters that control the deep convection, shallow convection, turbulence, cloud microphysics and cloud macrophysics processes in Community Atmosphere Model version 5 (CAM5). The Reed-Jablonowski TC test case is utilized and run at horizontal resolution of 0.5°×0.5° with 30 vertical levels. The sensitivity is assessed by the uncertainty each parameter exerts on simulated TC while perturbing it from its minimum to maximum with other 23 parameters set to their default value. The uncertainty is characterized by changes on simulated TC intensity (measured by absolute maximum wind speed at 100 m above surface), precipitation rate, shortwave cloud radiative forcing (SWCF), longwave cloud radiative forcing (LWCF), cloud liquid water path (LWP) and cloud ice water path (IWP), the latter five of which are quantified by their area-weighted value over the tropical cyclone region. Both the relative importance among these 24 physical parameters on TC simulation and the response function describing how they affect the six TC characteristics are quantified. It is found that the simulated TC intensity is most sensitive to the parcel fractional mass entrainment rate in Zhang-McFarlane (ZM) deep convection scheme. Decreasing this parameter enables a change from tropical depression to Category-4 storm. In contrast, other 23 physical parameters cause intensity uncertainty within 10 m/s. The precipitation rate, SWCF, LWP and IWP are also found to receive major impact from parameters in ZM deep convection scheme while the LWCF is dominated by parameters both in ZM deep convection and cloud microphysics scheme. The tunable parameters in University of Washington (UW) moist turbulence scheme, UW shallow convection scheme and cloud macrophysics are found to generally exert minor impact on TC simulation in CAM5. This study sheds light on improving the TC representation in AGCMs by tuning the physical parameters.

  12. Quantifying the Environmental Memory of Tropical Cyclones: Lingering Footprint or Climate Amnesia?

    NASA Astrophysics Data System (ADS)

    Schenkel, B. A.; Hart, R. E.

    2011-12-01

    One of the great remaining unanswered questions in tropical meteorology is why there are 90 tropical cyclones (TCs) globally, on average, per year as opposed to 10, 1000, or 10000 TCs. In contrast to extratropical cyclones whose annual frequency can be roughly calculated given the large scale characteristics of the mid-latitudes, there is no equivalent theory that even justifies the order of magnitude of TCs that occur globally each year. In spite of this, there appears to be a preferential spacing of approximately 1500-2000 km between TCs during multiple TC episodes in the Eastern North Pacific, North Atlantic, and Western North Pacific possibly suggesting that the number of storms in each basin is limited energetically by the environment. Reconciling these issues is fundamentally rooted in determining the role of TCs within the climate. Building upon previous research (e.g. Sobel and Camargo 2005, Hart et al. 2007), the following study seeks to take a preliminary step in addressing these questions by quantifying the spatiotemporal scales over which TCs and the large scale environment interact. Four-dimensional, storm-relative composites of raw variables, raw anomalies, and normalized anomalies for Western North Pacific TCs are utilized in the analysis presented here. Preliminary results show that the passage of a TC may be initially responsible for exciting a large scale cooling and drying of the atmospheric environment spanning the majority of the composite domain. Within two weeks, these anomalies are found to become localized over the region in which the TC directly passed through and most strongly manifest themselves as a drying of the lower and middle tropospheric environment. The spatial distribution of the moisture and temperature anomalies in the area immediately surrounding the TC track suggests that the suppression of convection potentially due to the underlying sea surface temperature cold wake induced by the TC is the predominant factor in anomaly maintenance. Furthermore, the periodic pulsation in the magnitude of the dry anomalies, approximately every 10 days following TC passage, either implies the passage of waves generated independently of the TC or in response to the passage of the TC itself that further serve to increase the stabilization of the atmospheric environment. In their totality, these results suggest that TCs serve as an efficient mechanism for regulating atmospheric instability within the tropics for weeks after TC passage.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  14. On the peculiar storm track of TC Favio during the 2006 2007 Southwest Indian Ocean tropical cyclone season and relationships to ENSO

    NASA Astrophysics Data System (ADS)

    Klinman, M. G.; Reason, C. J. C.

    2008-08-01

    The 2006 2007 Southern Indian Ocean tropical cyclone season proved to be devastating for the already flood-ravaged coastline of Mozambique. The landfall of Tropical Cyclone Favio on 22 February 2007 led to several deaths and considerable damage. A unique aspect of Tropical Cyclone Favio was its westward track around the southern tip of Madagascar and then northwestwards through the Mozambique Channel to make landfall in southern Mozambique most tropical cyclones in this region track southeastwards after approaching Madagascar and recurve back into the South Indian Ocean. In addition to its track, Tropical Cyclone Favio was highly unusual in that it made landfall in Mozambique during an El Niño year, an occurrence that has only happened one other time in the known record. It is shown that the impacts of the 2006 2007 El Niño over the South Indian Ocean (in terms of sea surface temperature and atmospheric circulation) were very different from previous El Niño events, thus helping to create more favourable conditions for landfall than would otherwise be expected. An analysis relating the unusual behaviour of Favio to the large scale climate mode patterns in 2006 2007 is presented. It is concluded that the unique track and anomalous landfall of Tropical Cyclone Favio are related and that seasonally-based statistical models for predicting the risk of landfall in Mozambique should be adjusted to accommodate anomalous circulation patterns that occur on synoptic to intraseasonal scales.

  15. Using the Variable-Resolution General Circulation Model CAM-SE to Simulate Regional Tropical Cyclone Climatology

    NASA Astrophysics Data System (ADS)

    Zarzycki, C. M.; Jablonowski, C.; Taylor, M. A.

    2012-12-01

    The ability of General Circulation Models (GCMs) to resolve tropical cyclones in the climate system has traditionally been difficult due to issues such as small storm size and the existence of key thermodynamic processes requiring significant parameterization. At traditional GCM grid resolutions of 50-300 km tropical cyclones are severely under-resolved, if not totally unresolved. Recent improvements in computational ability as well as advances in GCM model design now allow for simulations with grid spacings as small as 10-25 km. At these resolutions, models are able to more effectively capture key dynamical features of tropical cyclones. This paper explores a variable-resolution global model approach that allows for high spatial resolutions in areas of interest, such as low-latitude ocean basins where tropical cyclogenesis occurs. Such GCM designs with multi-resolution meshes serve to bridge the gap between globally uniform grids and limited area models and have the potential to become a future tool for regional climate assessments. A statically-nested, variable-resolution option has recently been introduced into the National Center for Atmospheric Research (NCAR) Community Atmosphere Model's (CAM) Spectral Element (SE) dynamical core. The SE dynamical core is also known as the 'High-Order Method Modeling Environment' (HOMME). We present aquaplanet climate experiments which showcase the ability of nested meshes to produce realistic tropical cyclones selectively in high resolution grids embedded within a global domain. We also evaluate model performance when coupled to an active land model and forced with historical sea surface temperatures by comparing multi-year results from variable-resolution CAM-SE to other globally-uniform high resolution tropical cyclone studies recently completed by the climate modeling community. Specific focus is paid to intensity profiles and track densities as well as the interannual variability in storm count in tropical regions of interest. We also discuss potential computational advantages of using scalable variable-resolution setups in either short-term process or long-term climate studies.

  16. Statistical features of tropical cyclones affecting China and its key economic zones

    NASA Astrophysics Data System (ADS)

    Chao, Qingchen; Chao, Jiping

    2012-12-01

    Recent trends and variability in tropical cyclone (TC) frequency and intensity are examined for TCs that affected China, with particular focus on those TCs that affected China's key economic zones (e.g., the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin area). The results show that the frequency of TCs affecting China weakly declined during the 1980s and 2000s, followed by a slight increase. The time series of TC frequency shows insignificant variations at periods of 2-6 yr during the past 60 years; these variations are significantly correlated with ENSO activity. The frequency of TCs affecting the Pearl River Delta area is strongly correlated with the ENSO cycle while the frequency of TCs affecting the Yangtze River Delta is not. The TC frequency varies differently for TCs of different intensities. Tropical storms (TSs) affecting China were small in total number, but have clearly increased in frequency. The frequencies of severe tropical storm (STS), typhoon (TY), severe typhoon (STY), and super typhoon (super TY) affecting China declined significantly during the 1970s and 1980s, but the numbers of STY and super TY have increased over the 2000s. The typical intensity of TCs affecting China declined over the 60-yr timeframe, but increased over the most recent 10 years (2000-2010). This increase in the intensity of TCs has particularly impacted the Yangtze River Delta area, which has experienced increased numbers of STYs and super TYs. These tendencies are observed in changes of the maximum intensity of TCs affecting both China in general and the Yangtze River Delta in particular during both the full 60-yr analysis period and the latest 10-yr period; however, these tendencies are not observed in changes of the average intensity of TCs. By contrast, both the extreme intensity and the average intensity of TCs affecting the Pearl River Delta have decreased throughout the analysis period, including the most recent decade.

  17. Interannual variation of the Philippines affecting tropical cyclone intensity and its possible causes

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Seon; Kim, Baek-Jo; Kang, Sung-Dae; Kim, Hae-Dong

    2015-10-01

    This study analyzed changes in tropical cyclone (TC) intensity for the past 62 years (1951-2012) by calculating annual average value of central pressure (CP) of TCs that affected the Philippines from July to September. Although TC intensity slightly weakened for the last 62 years, it was not statistically significant. In order to examine the causes of changes in intensity of TCs that influenced the Philippines, nine low CP years and nine high CP years among the 62 years were selected to analyze differences between the two groups. TCs largely occurred in the southeastern quadrant of tropical and subtropical western North Pacific during low CP years and tended to move to the Philippines from the far sea in the southeast of the nation. In differences in deep-layer-mean wind between the two groups, western North Pacific subtropical high (WNPSH) did not develop toward the middle latitudes of East Asia but toward the low latitudes of the region during low CP years. Therefore, TCs occurred in the southeastern quadrant of tropical and subtropical western North Pacific, triggering its movement of long distance westward toward the Philippines. As positive anomalies in precipitable water and at 600 hPa relative humidity, 850 hPa air temperature, and sea surface temperature continued to the Philippines from the southeastern quadrant, a favorable environment where intensity of TCs can be strengthened while they move to the Philippines during low CP years has been formed. In the end, because WNPSH developed toward the low latitudes during low CP years, anomalous easterlies that strengthened in the southern regions of WNPSH blew to the Philippines, and SST in the sea near the nation was heightened. Therefore, because TCs were able to obtain sufficient energy from the relatively warm sea while TCs moved a long distance to the Philippines, TC intensity was able to be strengthened.

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

    SciTech Connect

    Chen, Shu-Hua; Liu, Yi-Chin

    2014-10-27

    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 merger if it shifts southward. Another source of D-vortices is the westward propagating lows 27 along the southern edge of the Saharan air. The D-vortex merger process occurred for 63.5% of 28 tropical cyclones (TCs) or developing systems over the main development region of the Atlantic 29 Ocean, while it occurred for 54% of non-developing systems. TC genesis could be largely 30 controlled by the large-scale environment, but the differences in characteristics of vortices 31 associated with the D-vortex merger between developing and non-developing systems could 32 potentially help determine their destinies; in general, developing systems were dominated by a 33 more intense and moist south vortex, while non-developing systems were dominated by a north 34 vortex which was more intense, drier, and larger in size. Analysis also shows that 74% of intense 35 developing systems were involved with the D-vortex merger process. More attention needs to be 36 paid to the D-vortex merger and the characteristics of those vortices as they can play significant 37 roles or have a strong indication in Atlantic TC genesis.

  19. Analyzing the Multi-scale Interactions of Tropical Waves and Tropical Cyclone Formation with the NASA CMAVis System

    NASA Astrophysics Data System (ADS)

    Shen, B.; Nelson, B.; Tao, W.

    2011-12-01

    Among the scenarios in the Decadal Survey (DS) Missions, the advanced data processing group at the ESTO AIST PI workshop identified "Extreme Event Warning" and "Climate Projections" as two of the top priority scenarios. Recently, we (e.g., Shen et al., 2010a,b; 2011a,b) have made attempt of addressing the first by successfully developing the NASA Coupled Advanced global multiscale Modeling and concurrent Visualization systems (CAMVis) on NASA supercomputers, and demonstrating a great potential for extending the lead time (from 5~7 days up to 20 days) of tropical cyclone (TC) prediction with improved multi-scale interactions between a TC with large-scale environmental conditions such as African Easterly Waves (AEWs), and Madden Julian Oscillation (MJOs). In order to increase our confidence in long-term TC prediction and thus TC climate projection, the predictive relationships between large-scale tropical waves and TC formation need to be further examined and verified with massive model and satellite data sets. To achieve this goal, we have conducted multiscale analysis to study the TC genesis processes, accompanied downscaling (from large-scale events) and upscaling (from small-scale events) processes, and their subsequent non-linear interactions. In this study, we first illustrate the complicated multi-scale interactions during TC genesis with our newly-developed 3D streamline packages in the NASA CAMVis system. With selected cases that include twin TCs in 2002, TC Nargis (2008) and hurricane Helene (2006), we will show that the CAMVis can provide a detailed (zoomed-in) view on hurricane physical processes and an integrative (zoomed-out) view on its interactions with environmental conditions. In the end of talk, we will discuss our future work in multiscale analysis with the Hilbert Huang Transform and improved ensemble empiric mode decomposition.

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

    NASA Astrophysics Data System (ADS)

    Belanger, J. I.

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Zarzycki, C. M.; Jablonowski, C.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    India Meteorological Department (IMD) introduced the objective tropical cyclone (TC) track forecast valid for next 24 hrs over the North Indian Ocean (NIO) in 2003. It further extended the validity period up to 72 hrs in 2009. Here an attempt is made to evaluate the TC landfall forecast issued by IMD during 2003-2013 (11 years) by calculating the landfall point forecast error (LPE) and landfall time forecast error (LTE). The average LPE is about 67, 95, and 124 km and LTE is about 4, 7, and 2 hrs, respectively for 24, 48, and 72-hr forecasts over the NIO as a whole during 2009-2013. The accuracy of TC landfall forecast has been analysed with respect to basin of formation (Bay of Bengal, Arabian Sea, and NIO as a whole), specific regions of landfall, season of formation (pre-monsoon and post-monsoon seasons), intensity of TCs (cyclonic storm (CS), and severe cyclonic storm (SCS) or higher intensities) at the time of initiation of forecast and type of track of TCs (climatological/straight moving and recurving/looping type). The LPE is less over the BOB than over the AS for all forecast lengths up to 72 hrs. Similarly, the LPE is less during the post-monsoon season than during pre-monsoon season. The LPEs are less for climatologically moving/straight moving TCs than for the recurving/looping TCs. The LPE over the NIO has decreased at the rate of about 14.5 km/year during 2003-2013 for 24-hr forecasts. The LTE does not show any significant improvement for 24-hr forecast during the same period. There is significant decrease in LPE and LTE during 2009-2013 compared to 2003-2008 due to the modernisation programme of IMD. The 24-hr LPE and LTE have decreased from 157.5 to 66.5 km and 7.8 to 4.1 hrs, respectively. However, there is still scope for further reduction in 48 and 72-hr forecast errors over the NIO to about 50 and 100 km respectively based on the latest technology including aircraft reconnaissance, deployment of buoys, and assimilation of more observational data from satellite and Doppler weather radars, etc., in the numerical weather prediction (NWP) models during the next five years.

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

    NASA Astrophysics Data System (ADS)

    Griffin, Kyle S.

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

  4. Relationship between tropical cyclone activities in the Northwest Pacific area and the summer monsoon rainfall in the Northeast Asian region

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The study surveys the tropical cyclone (TC) activities in the Northwestern Pacific region during the summer monsoon season (SMS) (June-July) in the Northeast Asian region (North China, Korea, and Japan). The positive (negative) SMS rainfall years in the region show that not only the TC genesis frequency, but also the TC frequency which affects the Northeast Asian countries, are low (high) in the tropical and subtropical northwest Pacific. That is, the TCs mainly move to the southern part of China or up to the east sea far from Japan in the positive SMS rainfall years. The study analyzes the difference between the two groups in the 500 hPa streamline to investigate TC activities for the groups. The large-scale anomalous anticyclone and the anomalous cyclone were enlarged in the tropical and subtropical Northwestern Pacific and from Manchuria to the eastern Japan, respectively. Due to such anomalous pressure system patterns being strengthened during the positive SMS rainfall years, the tropical Northwestern Pacific below 20°N fortified anomalous easterlies, causing a lot of TCs during those years to move to the southern part of China along with these anomalous steering flows (anomalous easterlies). In addition, the anomalous anticyclone that is located in the tropical and subtropical Northwestern Pacific caused a low TC genesis frequency during the positive SMS rainfall years.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  9. Reconstruction of the North Atlantic tropical cyclones in Azores for the last 800 years.

    NASA Astrophysics Data System (ADS)

    Rubio-Ingles, Maria Jesus; Sánchez, Guiomar; Trigo, Ricardo; Francus, Pierre; Gonçalves, Vitor; Raposeiro, Pedro; Freitas, Conceiçao; Borges, Paolo; Hernández, Armand; Bao, Roberto; Vázquez-Loureiro, David; Andrade, Cesar; Sáez, Alberto; Giralt, Santiago

    2014-05-01

    The variability of North Atlantic tropical storms has been the focus of several studies. Duration and seasonality has been attributed to a number of climate patterns and processes such as El Niño-Southern Oscillation, Atlantic Meridional Mode, African easterly waves, and atmospheric Rossby waves, but their tracks have been widely related to the North Atlantic Oscillation. Several authors have pointed out an increase and track shifting of North Atlantic tropical cyclones since 1995 with increased probability of these turning north far away from the North American continent. However, this cannot be regarded as an infrequent phenomenon as most proxy records from the Atlantic North have shown the existence of similar patterns in the past. Sao Miguel Island (Azores archipelago, Portugal) is settled in the middle of the Atlantic Ocean. This location makes this island an excellent natural laboratory to record shifts on North Atlantic tropical storms tracks that can reach the archipelago as low intensity hurricanes (e.g. Nadine in 2012) or downgraded to tropical storm (e.g. Grace in 2009). In the present work, lake sediment records have been used as a proxy sensor of tropical storms. Lagoa Azul is located inside Sete Cidades volcanic caldera and its catchment is characterized by stepped and forested caldera walls. Tropical storms and heavy rainfalls produce a flashy and substantial enhancement in the erosion of the catchment, increasing the sediments reaching the lake by rockfalls deposits (in littoral zones) and flood events deposits (in offshore zones). These flood events can be recognized in the sedimentary record as lobe deposits dominated by terrestrial components. It can be found in the sedimentary record and the bathymetry. Instrumental meteorological data and historical records have been compiled to reconstruct the most recent history of the North Atlantic tropical storms that have landed or affected the Sao Miguel Island (Andrade et al., 2008). In addition, a 1.5 m long core allowed us to recover the whole sedimentary infill of Azul Lake, which has been characterized using a multiproxy (geochemistry, diatoms and chironomid head capsules) approach. The last 800 cal years BP, dated by the use of 14C (plant remains) and 210Pb, have been recorded in the 1.5 m of sediment. The layers of flood events deposits are characterized by low Ti content, no diatoms, and both high organic content and terrestrial plants remains. 14C and 210Pb dates obtained in this core have been used to link the flood events recorded in the offshore zones of the lake with the historical storms hitting the archipelago. According to the results of the studied sediment core, the number of tropical storms hitting the island has increased for the last 50 years. This is in accordance with the findings done by other authors (Liu et al., 2001 and Besonen et al., 2008). Moreover, two other periods located around the 1450s and the 1650s also recorded high number of storms. An increase of typhoons in China and hurricanes reaching the north Atlantic coast of United States during the same periods suggests a global climate pattern that ruled these extreme phenomena. LITERATURE: Andrade, C., Trigo R.M., Freitas, M.C., Gallego M.C., Borges, P., Ramos, A.M. (2008) "Comparing Historic Records of Storm frequency and the North Atlantic Oscillation (NAO) chronology for the Azores region", The Holocene, 18, 745-754 Besonen M.R., Bradley S.B., Mudelsee M., Abbott M.B, Francus P. (2008) "A 1000-year, annually-resolved record of hurricane activity from Boston, Massachussets" Geophysical Research Letters. Vol.35, L14705. Liu, K.-b., Shen, C. and Louie, K.-s. (2001), A 1,000-Year History of Typhoon Landfalls in Guangdong, Southern China, Reconstructed from Chinese Historical Documentary Records. Annals of the Association of American Geographers, 91: 453-464. doi: 10.1111/0004-5608.00253

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

    NASA Technical Reports Server (NTRS)

    Putnam, WilliamM.

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.

    2014-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  15. Tropical Cyclone Lightning Distribution and Its Relationship to Convection and Intensity Change

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward; Wienman, James; Pierce, Harold; Olson, William

    2000-01-01

    The long distance National Lightning Detection Network (NLDN) was used to monitor the distribution of lightning strokes in various 1998 and 1999 western North Atlantic tropical cyclones. These ground-based lightning observations together with the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) and the Tropical Rain Mapping Mission (TRMM) Microwave Instrument (TMI) derived convective rain rates were used to monitor the propagation of electrically charged convective rain bands aid to qualitatively estimate intensification. An example of the lightning analyses was performed on hurricane George between 25-28 September, 1998 when the system left Key West and moved towards the Louisiana coast. During this period of time, George's maximum winds increased from 38 to 45 meters per second on 25 September and then remained steady state until it made landfall. Time-radius displays of the lightning strokes indicated that the greatest number of lightning strokes occurred within the outer core region (greater than 165 km) with little or no lightning strokes at radii less than 165 km. The trend in these lightning strokes decreased as George move into the Gulf of Mexico and showed no inward propagation. The lack inward propagating lightning strokes with time indicated that there was no evidence that an eye wall replacement was occurring that could alter George's intensity. Since George was steady state at this time, this result is not surprising. Time-azimuth displays of lightning strokes in an annulus whose outer and inner radii were respectively, 222 and 333 km from George's center were also constructed. A result from this analysis indicated that the maximum number of strokes occurred in the forward and rear right quadrant when George was over the Gulf of Mexico. This result is, consistent with the aircraft and satellite observations of maximum rainfall.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  17. Sensitivity of the warm core of tropical cyclones to solar radiation

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    To investigate the impacts of solar radiation on tropical cyclone (TC) warm-core structure (i.e., the magnitude and height), a pair of idealized simulations are conducted by specifying different strengths of solar shortwave radiation. It is found that the TC warm core is highly sensitive to the shortwave radiative effect. For the nighttime storm, a tendency for a more intense warm core is found, with an elevated height compared to its daytime counterpart. As pointed out by previous studies, the radiative cooling during nighttime destabilizes the local and large-scale environment and thus promotes deep moist convection, which enhances the TC's intensity. Due to the different inertial stabilities, the diabatic heating in the eyewall will force different secondary circulations. For a strong TC with a deeper vertical structure, this promotes a thin upper-level inflow layer. This inflow carries the lower stratospheric air with high potential temperature and descends adiabatically in the eye, resulting in significant upper-level warming. The Sawyer-Eliassen diagnosis further confirms that the height of the maximum temperature anomaly is likely attributable to the balance among the forced secondary circulations.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Williams, Gabriel J.

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    PubMed

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

    Tweel, Andrew W; Turner, R Eugene

    2012-01-01

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

  5. The influence of mesoscale sea surface temperature gradients on tropical cyclones

    NASA Astrophysics Data System (ADS)

    Glazer, Russell Henderson

    The effects of mesoscale (50-1000km) sea surface temperature (SST) variability on tropical cyclones (TCs) are investigated with model simulations of an idealized TC as well as simulations of Hurricane Igor (2010) using the Weather Research and Forecasting (WRF) model. Mesoscale SST gradients significantly modify the surface wind speed and direction leading to areas of enhanced divergence/convergence and curl along the gradient. This paper explores the effects that these interactions between mesoscale SST gradients and the atmosphere have on TCs. In these idealized simulations it is shown that an SST gradient of similar scale to the idealized TC vortex produces asymmetry in the eyewall convection and leads to vertical misalignment of the vortex. Simulations of Igor are conducted with three different SST setups: a run with an unaltered SST field, a run with increased SST gradients, and a run with decreased SST gradients. Igor's intensity and structure is found to be sensitive to the three different SST setups but the specific mechanism could not be identified. It is found that the magnitude of moisture advection increases with increasing SST gradient magnitude on the warm side of a gradient.

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

    NASA Astrophysics Data System (ADS)

    Zheng, Yongguang; Chen, Jiong; Tao, Zuyu

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Gerstoft, Peter; Bromirski, Peter D.

    2010-08-01

    Nonlinear wave-wave interactions generate double-frequency (DF) microseisms, which include both surface waves (mainly Rayleigh-type) and compressional (P) waves. Although it is unclear whether DF surface waves generated in deep oceans are observed on land, we show that beamforming of land-based seismic array data allows detection of DF P waves generated by ocean waves from Super Typhoon Ioke in both pelagic and coastal regions. Two distinct spectral bands associated with different P-wave source locations are observed. The short-period DF band (0.16-0.35 Hz) is dominated by P waves generated in the deep ocean by local wind seas under the storm. In contrast, P waves in the long-period DF band (0.1-0.15 Hz) are weaker and generated closer to the coast of Japan from swell interactions. The accurate identification of DF P-wave microseism source areas is useful to monitor ocean wave-wave interactions due to tropical cyclones and to image Earth structure using ambient seismic noise.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2011-05-15

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