Sample records for classifying tropical cyclones

  1. Tropical cyclone formation

    SciTech Connect

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

    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.

  2. Tropical Cyclones John, Steve

    E-print Network

    Greenslade, Diana

    active, with a total of eight tropical cyclones detected in waters off northwest Australia (the waters hours with a maximum gust of 210 km/h (data courtesy of Robe River Iron Ore Automatic Weather Station of Cairns as a category 2 system on 27 February and weakened. The

  3. 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).

  4. 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.

  5. Tropical Cyclone Eye Thermodynamics

    Microsoft Academic Search

    H. E. Willoughby

    1998-01-01

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

  6. Tropical Cyclone Eye Dynamics.

    NASA Astrophysics Data System (ADS)

    Smith, R. K.

    1980-06-01

    A new perspective of the dynamics of a tropical cyclone eye is given in which eye subsidence and the adiabatic warming accompanying it are accounted for directly from the equations of motion. Subsidence is driven by an adverse, axial gradient of perturbation pressure which is associated principally with the decay and/or radial spread of the tangential wind field with height at those levels of the cyclone where the tangential winds are approximately in gradient wind balance. However, this pressure gradient is almost exactly opposed by the buoyancy force field due to adiabatic warming. This corroborates with observational data.The relationship between the present view of eye dynamics and those of Malkus and Kuo and a recent study by Willoughby is discussed in detail.

  7. Tropical cyclone genesis across palaeoclimates

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Tropical cyclone genesis is investigated for the Pliocene, Last Glacial Maximum (LGM) and the mid-Holocene through analysis of five climate models. The genesis potential index is used to estimate this from large scale atmospheric properties. The mid-Pliocene and LGM characterise periods where carbon dioxide levels were higher and lower than pre-industrial respectively, while the mid-Holocene differed primarily in its orbital configuration. The number of tropical cyclones formed each year is found to be fairly consistent across the various palaeoclimates. Although there is some model uncertainty in the change of global annual tropical cyclone frequency, there are coherent changes in the spatial patterns of tropical cyclogenesis. During the Pliocene and LGM, changes in carbon dioxide led to sea surface temperature changes throughout the tropics, yet the potential intensity of tropical cyclones appears relatively insensitive to these variations. Changes in tropical cyclone genesis during the mid-Holocene are observed to be asymmetric about the Equator: genesis is reduced in the Northern Hemisphere, but enhanced in the Southern Hemisphere. This is clearly driven by the altered seasonal insolation. Nonetheless, the enhanced seasonality may have driven localised effects on tropical cyclone genesis, through changes to the strength of monsoons and shifting of the inter-tropical convergence zone. Trends in future tropical cyclone genesis are neither consistent between the five models studied, nor with the palaeoclimate results. It is not clear why this should be the case.

  8. 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.

  9. Tropical Cyclone Intensity Analysis

    NSDL National Science Digital Library

    2014-09-14

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

  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. 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 ...

  12. Tropical Cyclone Report

    NSDL National Science Digital Library

    2007-12-12

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

  13. 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 ...

  14. Tropical Cyclone Report Hurricane Karen

    E-print Network

    of the Cape Verde Islands. The system moved west-northwestward with little change in organization until late of a tropical depression centered about 720 n mi west-southwest of the Cape Verde Islands at 0000 UTC 25Tropical Cyclone Report Hurricane Karen (AL122007) 25-29 September 2007 Richard J. Pasch National

  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. 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 ...

  17. 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.

  18. 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.

  19. Tropical Cyclone Report Hurricane Irene

    E-print Network

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

  20. Tropical Cyclone Report Hurricane Katrina

    E-print Network

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

  1. Tropical Cyclone Climatology

    NSDL National Science Digital Library

    This site contains figures and tables that describe the progress of a typical hurricane season in terms of the total number of tropical systems and hurricanes produced throughout the year in the Atlantic and East Pacific basins. The figures have curves which represent the average cumulative production of all named tropical systems, all hurricanes, and those hurricanes which were Category 3 or stronger in those basins. The tables list benchmark dates when a given number of tropical systems, hurricanes, or category 3 storms should have been generated. In the progress of the average Atlantic or East Pacific season based on 1944-1996 data, they show the date upon which the number of events would normally have occurred.

  2. The Dynamics and Predictability of Tropical Cyclones

    E-print Network

    Sippel, Jason A.

    2010-01-15

    Through methodology unique for tropical cyclones in peer-reviewed literature, this study explores how the dynamics of moist convection affects the predictability of tropical cyclogenesis. Mesoscale models are used to perform short-range ensemble...

  3. Tropical cyclone-ocea~ interactions Isaac Ginis

    E-print Network

    Rhode Island, University of

    /Oceanography, University 0/Rhode Island, USA. Abstract The advent of numerical weather prediction tropical cyclone models of these interactions in tropical cyclone intensity. Three-dimensional, coupled atmosphere-ocean models have recently/sea/surface wave numerical models with improved surface flux parameterizations, tested against high

  4. Objective classification of historical tropical cyclone intensity

    Microsoft Academic Search

    Michael Chenoweth

    2007-01-01

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

  5. Objective classification of historical tropical cyclone intensity

    Microsoft Academic Search

    Michael Chenoweth

    2007-01-01

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

  6. Interactions between climate and tropical cyclones

    NASA Astrophysics Data System (ADS)

    Webster, P. J.

    2007-05-01

    For the last 50 years, there have been two major thrusts in tropical cyclone research: determining the state of the atmosphere and ocean that is suitable for the formation of tropical storms (the genesis criteria) and short-term forecasting of the track and intensity of storms. Efforts to forecast seasonal storm activity, especially in the North Atlantic Ocean, have been undertaken through empirical means and, more recently, using low-resolution climate models. Climate model results have been exceptionally encouraging suggesting that the tropical cyclogenesis factors are predictable and are part of the large scale tropical circulation. During the last few years, a spate of papers has noted the relationship between changes in sea-surface temperature (SST) and tropical cyclone intensity and frequency. A critical issue is determining to what degree the frequency of hurricanes, as well as their intensity distribution, will change in a warming world. We discuss recent research regarding the interactions of the climate system with tropical cyclones, including the role of climate in determining the genesis of tropical cyclones and the role of tropical cyclones in the heat balance of the planet. Specifically: (i) We re-examine the genesis criteria of tropical cyclones and add two new criteria based on the behavior of waves in a flow varying in longitude and the inertial instability of equatorial flow in a cross-equatorial pressure gradient environment. Tropical cyclones are seen to form where the stretching deformation is negative and where large-scale waves transform into tight smaller and highly energetic scale vortices. We also discuss the tendency for storms to develop and intensify where the near-equatorial flow is inertially unstable. (ii) Tropical cyclones act to cool the tropical oceans by > 1K/year by evaporation of ocean surface water and by entrainment mixing with cooler water from below the mixed layer. We suggest that tropical cyclones are important part of the heat budget of the planet and act as efficient ventilators of the tropical ocean, transporting heat polewards in both the ocean and the atmosphere. We discuss the mechanisms by which hurricanes efficiently transport mass and heat upwards and then polewards and how the vertically mixed heat in the oceans joins the annual cycle of ocean heat transport. We speculate that the near constancy of the global annual number of tropical cyclones is evidence that the heat transport of storms is governed by an integral constraint applying to the heat balance of the planet. With this information, we can speculate on the characteristics of tropical cyclones in a warmer world.

  7. 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 ...

  8. Tropical Cyclones, Sea Surface Temperature, and Beyond

    NSDL National Science Digital Library

    Danielle Schmitt

    Part 1 The SAGUARO Exploring GIS Investigations for Earth Science curriculum requries the use of ESRI's ArcView GIS software version 3.0 for Macintosh or 3.2 and higher for PC. Use ArcGIS and data files from the SAGUARO Project's (http://www.scieds.com/saguaro/etc.html) Exploring Tropical Cyclones investigations. After the students are introduced to the program they are asked to determine what criteria are required for the formation of tropical cyclones. Exploring Tropical Cyclones Unit 1 has a great deal of data for the students to use. The data is presented as layers on a world map. Different features can be turned on and off at will, and layers can be brought in from other units if desired. Features they can work with are: August SST February SST tropical cyclone tracks locations of tropical cyclone formation for Jun-Sep locations of tropical cyclone formation for Dec-Mar Part 2 Students are divided into small groups (3-4 students works well) where they compare their findings (including what evidence they used) with the findings of the other group members. Each group is then asked to determine the threshold temperature for tropical cyclone formation as well as to calculate the area of the ocean that has SST equal to or above this threshold temperature (you can have them calculate this for each season, or as a total area including both February and August data). Part 3 Class discussion of what they have found so far. Introduce them to model predictions of SST for different atmospheric CO2 levels. Propose a 2 degree C increase in tropical SST and ask what they think that will mean. What other factors might influence the formation of tropical cyclones? Part 4 Assign an article or two (ideally a published peer reviewed article - to introduce them to this type of scientific writing - that is if you can find one that you consider appropriate for your students) that introduces them to other factors required for tropical cyclone formation and predictions of how climate change might affect them. For example an article that discusses the role of wind speed near the surface of the ocean, or vertical wind shear, or one that shows that the threshold temperature is actually predicted to increase by the same magnitude as the SST increase. Have them write a report that summaries the criteria for cyclogenesis as well as explaining how they would go about predicting where tropical cyclones will form as a result of an increased SST. They do not need to perform all of the tests they propose! They should state what sort of information they would like to obtain and why.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Tornadoes Associated with Cyclones of Tropical Origin-Practical Features

    Microsoft Academic Search

    E. L. Hill; William Malkin; W. A. Schulz Jr.

    1966-01-01

    The frequency of reports of tornadoes associated with tropical cyclones is shown to have increased during the past decade to a level worthy of professional attention.Tornado incidence is demonstrated to be related to the direction of movement of the tropical cyclone, and to the intensity of the cyclone as it approaches the coast. A heading slightly cast of north is

  16. Tropical cyclones over the Mediterranean Sea in climate change simulations

    Microsoft Academic Search

    M. A. Gaertner; D. Jacob; V. Gil; M. Domínguez; E. Padorno; E. Sánchez; M. Castro

    2007-01-01

    Tropical cyclones form only under specific environmental conditions. Anthropogenic climate change might alter the geographical areas where tropical cyclones can develop. Using an ensemble of regional climate models, we find an increase in the extremes of cyclone intensity over the Mediterranean Sea under a climate change scenario. At least for the most sensitive model, the increase in intensity is clearly

  17. 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

  18. 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.

  19. 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

  20. African aerosols and Atlantic tropical cyclone activities

    NASA Astrophysics Data System (ADS)

    Kafatos, M.; Sun, D.; Sahoo, A.

    2006-12-01

    Previous studies have shown that the Atlantic basin major hurricane (MH) activity is associated with western Sahelian monsoon rainfall, while rainfall in the Sahel is found to be highly anti-correlated with the African dust storms. So if the Atlantic basin MH activity may be anti-correlated with the African dust aerosols? In order to investigate the relationship between the African dust and the tropical cyclone (including both tropical storms and hurricanes) activities in the Atlantic basin, we explore how the African dust may link to Atlantic TC activity by using the long-term (1982-2005) NCEP Reynolds sea surface temperature (SST) product, and tropical cyclone (TC) data from the National Hurricane Center Best Track Files, and the TOMS aerosol index (AI) data, because the TOMS AI positive values are associated with UV-absorbing aerosols, like dust and smoke. Although no significant negative correlation between the TOMS AI and the Atlantic TC or MH frequency and duration is found, the initial locations of the Atlantic tropical cyclones did occur over the ocean where the aerosol loading was low. Our analysis shows that SST over the north tropical Atlantic ocean is anti-correlated with the TOMS aerosol index. This may be due to the radiative forcing of the aerosols. The effects of the dust aerosols carried across the West African region led to a lowering of SST and therefore inhibited tropical cyclogenesis. During 2005, the aerosol loading along the western African coast was unusually low, while the SST over the main development region (MDR) was abnormally high, and the Atlantic TC/hurricane activities became record strong. We propose future observations to test these results.

  1. FAQ: Hurricanes, Typhoons, and Tropical Cyclones

    NSDL National Science Digital Library

    Christopher Landsea

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

  2. Tropical Cyclone Tornadoes, 1950–2007

    Microsoft Academic Search

    Lori A. Schultz; Daniel J. Cecil

    2009-01-01

    An expanded ''climatology'' of U.S. tropical cyclone (TC) tornadoes covering the period 1950-2007 is presented. A major climatology published in 1991 included data on 626 TC tornadoes. Since then, almost 1200 more TC tornado records have been identified, with almost half of that number from the 2004-05 seasons alone. This work reexamines some findings from previous studies, using a substantially

  3. Remote forcing of water levels by tropical cyclones in southwest Australia

    NASA Astrophysics Data System (ADS)

    Eliot, Matthew; Pattiaratchi, Charitha

    2010-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. 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

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

    PubMed

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

    2012-09-01

    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

  7. 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 ...

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

    E-print Network

    Murphy, Maurice D

    2008-01-01

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

  9. CYGNSS: NASA Earth Venture Tropical Cyclone Mission

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  10. The dynamics and energetics of mature tropical cyclones

    Microsoft Academic Search

    Richard A. Anthes

    1974-01-01

    Rapid progress toward the understanding of tropical cyclones has been made during the past 10 years, largely as a result of the development of numerical models. The dynamics and energetics of the mature tropical cyclone are reviewed in this article. First, the pressure, wind, temperature, and moisture structures of the hurricane are summarized. Then a scale analysis is applied over

  11. Developing a Parameter for Forecasting Tornadoes in Landfalling Tropical Cyclones

    Microsoft Academic Search

    Matthew John Onderlinde

    2009-01-01

    Tornado reports are combined with hurricane data to generate a dataset of tornadoes associated with tropical cyclones affecting the coastal Gulf of Mexico and Florida’s East Coast between 2000 – 2008. A pool of 28 potential predictors of tornado occurrence in tropical cyclone environments is narrowed to 7 using classic stepwise regression. The result is a composite parameter for forecasting

  12. Satellite-Derived Rain Rates in Varying Tropical Cyclone Environments

    Microsoft Academic Search

    D. J. Cecil; M. Wingo

    2006-01-01

    When tropical cyclones interact with environmental vertical wind shear, they often take on an asymmetric structure. Prior observational and modeling studies have identified a preference for rainfall enhancement in the directions that are down shear and also to the left of the shear vector. This study composites hundreds of snapshots of the rain fields for Atlantic tropical cyclones between 1988-2005,

  13. Investigating the surface effects of a tropical cyclone

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-10-01

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

  14. Tropical Cyclone Boura on November 17, 2002

    NSDL National Science Digital Library

    Lori Perkins

    2002-11-21

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

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

    PubMed

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

    2013-12-01

    The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence. PMID:24305147

  16. 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.

  17. Tropical Cyclone Crystal on December 25, 2002

    NSDL National Science Digital Library

    Lori Perkins

    2002-12-30

    Tropical Cyclone Crystal approaches the island of Mauritius in the Indian Ocean. The storm packed sustained winds of 80 miles per hour with gusts up to 96 miles per hour. Mauritius is situated east of Madagascar off of the Africas southeastern coast. This animation shows the storms rain structure with 5 different isosurfaces. The first isosurface is grey and depicts areas with 0.5 inches of rain per hour. The second is light blue and reflects 1.0 inches of rain per hour. The third is green and shows 1.7 inches of rain per hour. The forth is yellow and represents 2.0 inches of rain per hour. The last isosurface is red and shows 2.2 inches or more of rain.

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

    E-print Network

    Fang, Yuguang "Michael"

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

  19. 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-2010, the average numbers per year were as follows: Atlantic Ocean, Caribbean or Gulf of Mexico: 11 tropical storms, 6 of which became hurricanes East Pacific Ocean: 15 tropical storms, 8 of which became hurricanes

  20. 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 ...

  1. 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.

  2. Animation of Flood Potential from Two Australian Tropical Cyclones - Duration: 0:06.

    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 ...

  3. 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 ...

  4. The Deadliest Atlantic Tropical Cyclones, 1492-1996

    NSDL National Science Digital Library

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

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

    NASA Video Gallery

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

  6. Ozone Measurements from Atlantic Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Carsey, T. P.; Willoughby, H. E.

    2001-12-01

    Tropical cyclones (TCs, hurricanes) are episodic mesoscale features of the tropical and subtropical oceans that are likely to have a large impact on the distributions and fluxes of trace gases. The troposphere boundary layer, possibly enriched by enhanced exchange of dissolved gases from the sea surface, is transported upward as high as 15 km and redistributed over a large horizontal area. Measurements of selected trace gases should therefore be useful in understanding hurricane dynamics and structure; for example, to resolve an ongoing controversy about the lifetime of air within the eye and mixing areas of the eye wall boundary (Willoughby, Mon. Wea. Rev. 126, 3053, 1998). However, few systematic measurements of significant trace gases in TCs have been obtained. NOAA-AOML has measured ozone (O3) in eyewall crossings for a number of Atlantic TCs during the 1998 and 1999 seasons on board NOAA P-3 hurricane research flights. Ozone concentrations showed considerable variation across the eye wall and within the eye; significant changes were also observed as the hurricane aged. These results, related measurements, and their implications for TC structure and marine tropospheric chemistry will be presented.

  7. Topographic Rossby Waves Generated by Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Dukhovskoy, D. S.; Morey, S. L.

    2013-05-01

    Analytical and numerical studies suggest that given appropriate slope, the ocean responds to a tropical storm with low-frequency motions trapped over a continental slope, the Coastal Trapped Waves. The presented study is focused on Topographic Rossby Waves (TRW), sub-inertial oscillations propagating over a sloping bottom. Generation and propagation of TRW under barotropic (Continental Shelf Waves or Shelf Waves) and baroclinic (Bottom Trapped Waves) approximations are discussed. A real-case model study of a storm surge in Apalachee Bay, northeastern Gulf of Mexico during Hurricane Dennis (July, 2005) is presented to demonstrate the role of the shelf waves in coastal inundation. The presentation also discusses excitation of baroclinic bottom-intensified wave motions on the continental slope by a tropical cyclone. An idealized model experiment demonstrates that a continental shelf that (1) responds to a storm as a baroclinic ocean and (2) has a slope steep enough to dominate the planetary ?-effect (but small enough to prevent internal Kelvin-type modes) can support baroclinic topographic waves.

  8. 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.

  9. 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.

  10. Archive Compiles New Resource for Global Tropical Cyclone Research

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  11. Tropical cyclone Marlene and stratosphere-troposphere exchange

    Microsoft Academic Search

    Jean-Luc Baray; Gérard Ancellet; Tantely Randriambelo; Serge Baldy

    1999-01-01

    Convective tropical cyclones initiate exchanges of mass and energy between the troposphere and the stratosphere. Recent analyses of ozone and water vapor measurements from Measurements of Ozone by Airbus In-Service Aircraft (MOZAIC) data [Suhre et al., 1997] suggest that stratospheric ozone inputs to the troposphere can occur in the tropics near zones of deep convection. In the present paper, we

  12. 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.

  13. Tropical Cyclone Kesiny northeast of Madagascar, Indian Ocean

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Tropical Cyclone Kesiny can be seen over the Indian Ocean in this true color image taken on May 6, 2002, at 6:45 UTC by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. When this image was taken, the cyclone was several hundred miles east of northern Madagascar and packing winds of up to 120 kilometers (75 miles) per hour. As the cyclone continues its approach southwest into Madagascar, it is forecast to increase in intensity and generate sustained winds of up to 139 kilometers (86 miles) per hour. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  14. Temporal clustering of tropical cyclones and its ecosystem impacts.

    PubMed

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

    2011-10-25

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

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

    E-print Network

    Emanuel, Kerry A.

    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

  16. 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

  17. On steady-state tropical cyclones Roger K. Smitha , Michael T. Montgomeryb and John Persingb

    E-print Network

    Smith, Roger K.

    On steady-state tropical cyclones Roger K. Smitha , Michael T. Montgomeryb and John Persingb examine the physical constraints that must be satisfied to allow for a steady- state tropical cyclone and question whether globally steady-state tropical cyclone solutions have merit. The implications for previous

  18. 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

  19. Observations of Particle Size and Phase in Tropical Cyclones: Implications for Mesoscale Modeling of Microphysical Processes

    Microsoft Academic Search

    Greg M. McFarquhar; Robert A. Black

    2004-01-01

    Mesoscale model simulations of tropical cyclones are sensitive to representations of microphysical processes, such as fall velocities of frozen hydrometeors. The majority of microphysical parameterizations are based on observations obtained in clouds not associated with tropical cyclones, and hence their suitability for use in simulations of tropical cyclones is not known. Here, representations of mass-weighted fall speed Vm for snow

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

    E-print Network

    Rothman, Daniel

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

  1. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Farfán, L. M.; Raga, G. B.

    2009-05-01

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

  4. 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.

  5. A “sufficient” condition combination for rapid intensifications of tropical cyclones

    Microsoft Academic Search

    Ruixin Yang; Donglian Sun; Jiang Tang

    2008-01-01

    Rapid Intensifications (RI) of tropical cyclones (TCs) provide major error sources in the challenging task of TC intensity forecasting. There are many factors that affect the RI processes of TCs, and identifying the combination of conditions most favorable to RI development is very time consuming when using traditional statistical data analysis methods. Data mining techniques are implemented to the data

  6. Improved associated conditions in rapid intensifications of tropical cyclones

    Microsoft Academic Search

    Ruixin Yang; Jiang Tang; Menas Kafatos

    2007-01-01

    Rapid intensification (RI) of tropical cyclones (TC) is a major error source in TC intensity forecasting. In order to improve the estimates of RI probability, association rules are used to facilitate the process of mining for candidate sets of conditions. Compared to the relation analysis method, the technique of association rules can simply explore associations among multiple conditions. Our mining

  7. Barotropic instability in the tropical cyclone outer region

    Microsoft Academic Search

    Jiayi Peng; Tim Li; Melinda S. Peng; Xuyang Ge

    2009-01-01

    The growth of asymmetric perturbations and their interactions with the symmetric flow are investigated for wind profiles in a tropical cyclone with instability in its outer region. Three tangential wind profiles are examined: TC1, a strong barotropic instability profile in the outer region; TC2, a stable wind profile; and TC3, a weaker instability profile comparing to TC1 with a larger

  8. Future economic damage from tropical cyclones: sensitivities to societal and

    E-print Network

    Colorado at Boulder, University of

    in the politics of global warming with images of human impacts of hurricanes and tropical cyclones often used to losses, often called climate adaptation, have far greater potential effectiveness to reduce damage policies when far more potentially effective options are available. Keywords: climate change; disasters

  9. African Lightning: Indicator of Tropical Atlantic Cyclone Formation

    NASA Astrophysics Data System (ADS)

    Chronis, Themis; Williams, Earle; Anagnostou, Emmanouil; Petersen, Walter

    2007-10-01

    Each year, devastating hurricanes originating from the tropical Atlantic Ocean cause severe loss of life and property damage. Efforts to predict and forecast the behavior of such phenomena range from satellite-derived sea surface temperatures to coupled ocean-atmosphere models. Nonetheless, predicting cyclone occurrence and behavior remains elusive.

  10. Atlantic Tropical Cyclones Variability and Time Series Analysis

    Microsoft Academic Search

    C. Andronache; V. Phillips

    2008-01-01

    Formation and evolution of Atlantic tropical cyclones (ATC) is typically investigated using: 1) short-term forecasting of the track and intensity of storms based on high resolution mesoscale models, and 2) statistical forecast of seasonal storm activity. The underlying assumption of statistical methods is that physical precursors in the ocean-atmosphere system determine the probability of genesis and development of ATC. Recently,

  11. Satellite-derived rain rates in vertically sheared tropical cyclones

    Microsoft Academic Search

    Daniel J. Cecil

    2007-01-01

    When tropical cyclones interact with environmental vertical wind shear, they often take on an asymmetric structure. Prior observational and modeling studies have identified a preference for rainfall enhancement in the directions that are down shear and also to the left of the shear vector (in the Northern Hemisphere). This study composites hundreds of snapshots of the rain fields for Atlantic

  12. In-Situ Observations in Tropical Cyclones from Ocean Drifters

    NASA Astrophysics Data System (ADS)

    Morzel, J.; Centurioni, L. R.

    2013-05-01

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

  13. 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.

  14. 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.

  15. Tropical cyclone track forecasting techniques ? A review

    NASA Astrophysics Data System (ADS)

    Roy, Chandan; Kovordányi, Rita

    2012-02-01

    Delivering accurate cyclone forecasts in time is of key importance when it comes to saving human lives and reducing economic loss. Difficulties arise because the geographical and climatological characteristics of the various cyclone formation basins are not similar, which entail that a single forecasting technique cannot yield reliable performance in all ocean basins. For this reason, global forecasting techniques need to be applied together with basin-specific techniques to increase the forecast accuracy. As cyclone track is governed by a range of factors variations in weather conditions, wind pressure, sea surface temperature, air temperature, ocean currents, and the earth's rotational force?the coriolis force, it is a formidable task to combine these parameters and produce reliable and accurate forecasts. In recent years, the availability of suitable data has increased and more advanced forecasting techniques have been developed, in addition to old techniques having been modified. In particular, artificial neural network based techniques are now being considered at meteorological offices. This new technique uses freely available satellite images as input, can be run on standard PCs, and can produce forecasts with good accuracy. For these reasons, artificial neural network based techniques seem especially suited for developing countries which have limited capacity to forecast cyclones and where human casualties are the highest.

  16. THE DVORAK TROPICAL CYCLONE INTENSITY ESTIMATION TECHNIQUE

    E-print Network

    . The technique has likely saved tens of thousands of lives in regions where over one billion people are directly affected by TCs (commonly called hurricanes, typhoons, or cyclones). The Dvorak technique's practical of Hurricane Katrina, viewed from GOES-12 on 28 August 2006 BY CHRISTOPHER VELDEN, BRUCE HARPER, FRANK WELLS

  17. Tree-ring isotope records of tropical cyclone activity.

    PubMed

    Miller, Dana L; Mora, Claudia I; Grissino-Mayer, Henri D; Mock, Cary J; Uhle, Maria E; Sharp, Zachary

    2006-09-26

    The destruction wrought by North Atlantic hurricanes in 2004 and 2005 dramatically emphasizes the need for better understanding of tropical cyclone activity apart from the records provided by meteorological data and historical documentation. We present a 220-year record of oxygen isotope values of alpha-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 and 20th century landfalling/near-coastal tropical storms and hurricanes. Our results suggest the potential for a tree-ring oxygen isotope proxy record of tropical cyclone occurrence extending back many centuries based on remnant pine wood from protected areas in the southeastern U.S. PMID:16984996

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  19. The Relationship Between Tropical Cyclone Frequency and 'Climate Change'

    NASA Astrophysics Data System (ADS)

    Bolton, M.; Mogil, M.

    2013-12-01

    Please note: there have been minor updates to this work since the main author, Matt Bolton, graduated high school, but the majority of the research was compiled by him while he was a high school junior in 2011. Abstract: In recent years, there has been a growing trend by many, in the meteorological community (media and scientist) to predict expected seasonal tropical cyclone frequency in the Atlantic and Pacific Basins. Typically, the numbers are related to seasonal averages. However, these predictions often show a large positive bias (i.e., there are more years in which the expected number of storms exceeds or far exceeds average). Further, observed numbers often come close to bearing out the forecasts (actually a good thing). From a public perspective (and based on extrapolations performed by media and some scientific groups), this peaking of Atlantic tropical cyclone activity is observed globally. In an attempt to determine if such a global trend exists, we set out to collect data from weather agencies around the world and present it in a way that was as unbiased as possible. While there were inconsistencies across the various datasets, especially in regard to wind data, we were still able to construct a realistic global cyclone database. We have concluded that high activity levels in one basin are often balanced by areas of low activity in others. The Atlantic - Eastern Pacific couplet is one such example. This paper will serve as an update to our previous 2011 paper, which introduced our efforts. At that time, we found, on average, 70 named tropical cyclones worldwide. In both this and our original study, we did not address the issue of naming short-lived tropical systems, which was found to be inconsistent across worldwide ocean basins. Our results suggest, that from a global climate change perspective, a growing NUMBER of tropical cyclones is NOT being observed. In the current iteration of our study, we are examining, at least preliminarily, global Accumulated Cyclone Energy (ACE) values. As these values are computed more widely in the coming months, we also hope to include a breakdown of worldwide tropical systems by category and duration.

  20. Coastal Hazard due to Tropical Cyclones in Mexico

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Walsh, Kevin

    2015-02-01

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

  3. Relating Convective and Microphysical Properties to Large-scale Dynamical and Thermodynamical processes within Tropical Cyclones

    Microsoft Academic Search

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

    2008-01-01

    It is well known that precipitating convection within tropical cyclones result from a complex interactions among large-scale, storm-scale, cloud-scale, and micro-scale processes. For improved representation of these processes within tropical cyclone models, it is crucial to first understand how micro-scale and cloud- scale properties within tropical cyclones are related to large-scale processes, one of the key objectives of the Year

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

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward; Pierce, Harold; Adler, Robert

    1999-01-01

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

  5. Three-dimensional spiral structure of tropical cyclone under four-force balance

    NASA Astrophysics Data System (ADS)

    Liu, Shi-Kuo; Fu, Zun-Tao; Liu, Shi-Da

    2014-06-01

    The steady axis-symmetrical atmosphere dynamical equations are used for describing spiral structure of tropical cyclones under four-force (pressure gradient force, Coriolis force, centrifugal force, and friction force) balance, and the dynamical systems of three-dimensional (3D) velocity field are introduced. The qualitative analysis of the dynamical system shows that there are down 3D spiral structures in eye of tropical cyclone and tropical cyclone is 3D counterclockwise up spiral structure. These results are consistent with the observed tropical cyclone on the weather map.

  6. NASA Sees Heavy Rainfall, Hot Towers in Tropical Cyclone Nathan - Duration: 0:15.

    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...

  7. The Moist Entropy Change in Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Juracic, Ana

    2012-10-01

    Important part of moist entropy budget is the advection of moist entropy in or out of the system, due to interaction of wind and moist entropy fields. The dropwindsonde data from several tropical storms is used to calculate both of those fields, as well as the resulting flow. In order to determine if the storm is exporting or importing moist entropy, the advection is horizontally averaged and vertically integrated. The storms of interest were Alex, Karl, Gaston and Fanapi from 2010. First three occurred in Atlantic basin while Fanapi evolved over Pacific basin. Gaston is the only one that was not developing during dropsonde missions, so it can be used as some kind of indicator of non-developing features in the entropy flux. The data show that during the development of the storm, the values of the moist entropy export are lower than for non-developing systems.

  8. 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…

  9. Trend Analysis with a New Global Record of Tropical Cyclone Intensity JAMES P. KOSSIN

    E-print Network

    Kossin, James P.

    Trend Analysis with a New Global Record of Tropical Cyclone Intensity JAMES P. KOSSIN NOAA-nineteenth century in some regions, but formal analysis of these records is encumbered by temporal heterogeneities in the data. This is particularly problematic when attempting to detect trends in tropical cyclone metrics

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

    E-print Network

    Businger, Steven

    interaction between an active, vigorously degassing volcano and a tropical cyclone captured by a vog (volcanic into a tropical cyclone. Results from the vog dispersion model are compared with Geostationary Operational the dispersion of emissions (vog) from Kilauea volcano across the island of Hawai`i and the other main Hawaiian

  11. 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

  12. 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.

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

    Microsoft Academic Search

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

    2009-01-01

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

  14. Distinct effects of anthropogenic aerosols on tropical cyclones

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Ma, Leiming; Duan, Yihong; Zhu, Yongti

    2004-12-01

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

  17. Quantification of Tropical Cyclone track variability in climate models

    NASA Astrophysics Data System (ADS)

    Daloz, A.; Kossin, J. P.; Vimont, D.; Emanuel, K.; Camargo, S. J.

    2012-12-01

    Observations as well as downscaling simulations driven by reanalysis data indicate an increase in tropical cyclone (TC) power dissipation index (PDI) in the late 20th century over the North Atlantic basin (Emanuel et al. 2012). A change in the mean state of TC tracks is certainly partly responsible for this PDI increase (Kossin and Vimont 2007). Kossin et al. (2010) identified a shift in TC tracks due to more an increasing proportion of deep-tropical storms and a decreasing proportion of baroclinically influenced storms. The first question we are trying to answer here is how much this track shift contributes to the PDI increase of the late 20th century. The analyses of CMIP5 simulations suggest that no detectable change in PDI should be present in the late 20th century (Villarini et al. 2012). Thus the second point of this study is: are the GCMs capable of simulating this shift of the TC tracks? Would the misrepresentation of the track shift be responsible for the lack of change in PDI in the late 20th century in GCMs? References: Emanuel, K., Solomon, S., Folini, D., Davis, S. and Cagnazzo, C., 2012. Influence of tropical tropopause layer cooling on Atlantic hurricane activity. Journal of Climate, in review. Kossin J.P., Camargo S.J. and Sitkowski M., 2010: Climate modulation of North Atlantic hurricane tracks. Journal of Climate, 23, 3057-3076. Kossin J.P. and Vimont D., 2007: Kossin, J. P., and D. J. Vimont, 2007: A more general framework for understanding Atlantic hurricane variability and trends. Bull. Amer. Meteor. Soc., 88, 1767-1781. Villarini G. and Vecchi G. A., 2012: Projected Increases in North Atlantic Tropical Cyclone Intensity from CMIP5 Models. Submitted to the Journal of Climate.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  19. 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

  20. Assessment of Tropical Cyclone Track Forecast Errors using GDAPS (UM)

    NASA Astrophysics Data System (ADS)

    Kim, D.; Kim, J.; Chang, K.; Byun, K.; Lee, J.

    2013-12-01

    After the Joint Typhoon Warning Center (JTWC) began issuing official five-day tropical cyclone (TC) forecasts in 2003, the Korea Meteorological Administration (KMA) started issuing official five-day forecasts of TCs in May 2012 after 2 year of beta test. Forming a selective consensus (SCON) by proper removal of a likely erroneous track forecast is hypothesized to be more accurate than the non-selective consensus (NCON) of all model tracks that are used for the five-day forecasts. Conceptual models describing large track error mechanisms, which are related to known tropical cyclone motion processes being misrepresented in the dynamical models, are applied to forecasts during the 2012 western North Pacific typhoon season by the Global Data Assimilation and Prediction System (GDAPS (UM N512 L70)) which is KMA's main operational model. GDAPS (UM) is one of consensus members used in making KMA's five-day forecasts and thus analysis of its track error tendencies would be useful for forming a SCON forecast. All 72-h track errors greater than 320 km are examined on the basis of the approach developed by Carr and Elsberry (2000a, b). Tropical-influenced error sources caused 37% (47 times / 126 erroneous forecasts) of the GDAPS (UM) large track forecast errors primarily because an incorrect beta effect-related process depicted by the model contributed to the erroneous forecasts. Midlatitude-influenced error sources accounted for 63% (79 times / 126 error cases) in the GDAPS (UM) erroneous forecasts mainly due to an incorrect forecast of the midlatitude system evolutions. It is proposed that KMA will be able to issue more reliable TC track information if a likely model track error is recognized by optimum use of conceptual models by Carr and Elsberry (2000a, b) and a selective consensus track is then the basis for an improved warning.

  1. 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.

  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. 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

  4. 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.

  5. 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.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2001-01-01

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

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

    E-print Network

    Sobel, Adam

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

  8. Ocean feedback to tropical cyclones: climatology and processes

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. 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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  11. 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.

  12. Evidence of the Gulf Stream's influence on tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Bright, Robert J.; Xie, Lian; Pietrafesa, Leonard J.

    2002-08-01

    Historical storm data and satellite imagery are analyzed to determine the intensity changes and storm-related characteristics of 53 coastal and landfalling tropical cyclones (TCs) from Florida to North Carolina that passed over the Gulf Stream (GS) during the period 1944-2000. It appears that less intense storms (Category 2 or weaker), as well as those occurring earlier in the Atlantic hurricane season, are more likely to be strengthened by the GS. In addition, 81% of the Category 2 or weaker storms that intensified based on both maximum wind speed (MWS) and minimum central pressure (MCP) had tracks approximately parallel to the GS, while 3 of the 5 major (Category 3-5) hurricanes that intensified based on both MWS and MCP tracked perpendicular to the GS. The presence of an upstream mid-latitude trough could have contributed to the intensification of the weaker TCs by steering them along the GS.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    Microsoft Academic Search

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

    2005-01-01

    A version of the WAVEWATCH III wave model featuring a continuously moving spatial grid is presented. The new model option\\/version is intended for research into wind waves generated by tropical cyclones in deep water away from the coast. The main advantage of such an approach is that the cyclones can be modeled with spatial grids that cover much smaller areas

  16. T TROPICAL CYCLONES AND CLIMATE WORKSHOP WHAT: Experts assembled to provide a unique assessment

    E-print Network

    Sobel, Adam

    topic. The extreme Atlantic hurricane season of 2005, and the disastrous consequences of Katrina cyclones (TCs) are among the most destructive of natural disasters. The statistics of TC occurrence are poorly understood. Even less is known about the influence of tropical cyclones on the large-scale climate

  17. Impact of a tropical cyclone on biogeochemistry of the central Arabian Sea

    Microsoft Academic Search

    Hema Naik; S. W. A. Naqvi; T. Suresh; P. V. Narvekar

    2008-01-01

    Remotely sensed data are combined with shipboard measurements to investigate biogeochemical changes caused by a moderate tropical cyclone in the central Arabian Sea in December 1998. The sea surface temperature decreased by ?4°C, whereas surface nitrate and chlorophyll concentrations increased by >5 ?M and up to 4 mg m?3, respectively, over a large area affected by the cyclone. Nutrient enrichment

  18. GPM Rain Rates in Tropical Cyclone Pam - Duration: 0:15.

    NASA Video Gallery

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

  19. 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 ...

  20. 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 ...

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

    NASA Video Gallery

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

  2. 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 ...

  3. 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 ...

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

    NASA Video Gallery

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

  5. 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 ...

  6. 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 ...

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

    NASA Video Gallery

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

  8. 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...

  9. 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 ...

  10. 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 ...

  11. NOTES AND CORRESPONDENCE Multidecadal Variability in North Atlantic Tropical Cyclone Activity

    E-print Network

    Gray, William

    NOTES AND CORRESPONDENCE Multidecadal Variability in North Atlantic Tropical Cyclone Activity suggested. Several previous studies have discussed observed multidecadal variability in the North Atlantic on far North Atlantic sea surface temperature anomalies and basinwide North Atlantic sea level pressure

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

    NASA Video Gallery

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

  13. 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 ...

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

    Microsoft Academic Search

    Peter S. Grimbacher; Nigel E. Stork

    2009-01-01

    There are surprisingly few studies documenting effects of tropical cyclones (including hurricanes and typhoons) on rainforest\\u000a animals, and especially insects, considering that many tropical forests are frequently affected by cyclonic disturbance. Consequently,\\u000a we sampled a beetle assemblage inhabiting 18 upland rainforest sites in a fragmented landscape in north-eastern Queensland,\\u000a Australia, using a standardised sampling protocol in 2002 and again 12 months

  15. A novel web-based system for tropical cyclone analysis and prediction

    Microsoft Academic Search

    Yee Leung; Man Hong Wong; Ka Chun Wong; Wei Zhang; Kwong Sak Leung

    2012-01-01

    A web-based system is developed for the analysis and prediction of tropical cyclones, particularly their landfalls and recurvatures. To facilitate accessibility to the system, its development is based on Google Maps application programming interface (API), Java and client\\/server architecture. In addition to the construction of a powerful query system for the multi-source, multi-scale and multi-level tropical cyclone database, data mining

  16. A tangential wind profile for simulating strong tropical cyclones with MM5

    Microsoft Academic Search

    Shanhong Gao; Bo Yang; Zengmao Wu

    2005-01-01

    A new tangential wind profile for simulating strong tropical cyclones is put forward and planted into the NCAR-AFWA tropical\\u000a cyclone bogussing scheme in MM5. The scheme for the new profile can make full use of the information from routine typhoon\\u000a reports, including not only the maximum wind, but also the additional information of the wind speeds of 25.7 and 15.4

  17. 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.

  18. 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

    2014-06-01

    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.

  19. An Exploration of Tropical Cyclone Simulations in NCAR's Community Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Reed, Kevin A.

    Using General Circulation Models (GCMs) for tropical cyclone studies is challenging due to the relatively small size of the storms, the intense convection and a host of scale interactions. However, with the advancement of computer architectures, GCMs are becoming capable of running at high horizontal resolutions with grid spacings of less than 60 km. As a result, high-resolution GCMs are becoming a tool of choice to evaluate tropical cyclones in current and future climate conditions. This raises questions concerning the fidelity of GCMs for tropical cyclone assessments. The physical and dynamical components of GCMs need to be evaluated to assess their reliability for tropical cyclone studies. An idealized tropical cyclone test case for high-resolution GCMs is developed and implemented in aqua-planet mode with constant sea surface temperatures. The initial conditions are based on an analytic initial vortex seed that is in gradient-wind and hydrostatic balance and intensifies over a 10-day period. The influence of the model parameterization package on the development of the tropical cyclone is assessed. In particular, different physics parameterization suites are investigated within the National Center for Atmospheric Research's Community Atmosphere Model CAM, including physics versions 3.1, 4 and 5. The choice of the CAM physics suite has a significant impact on the evolution of the idealized vortex into a tropical cyclone. In addition, a test case of intermediate complexity is introduced. Therein it is suggested that a GCM dynamical core be paired with simple moist physics to test the evolution of the test vortex. This simple-physics configuration includes important driving mechanisms for tropical cyclones, including surface fluxes, boundary layer diffusion and large-scale condensation. The impact of the CAM dynamical core (the resolved fluid flow component) on the tropical cyclone intensity and size is evaluated. In particular, the finite-volume, spectral element, Eulerian spectral transform and semi-Lagrangian spectral transform dynamical cores are utilized. The simple-physics simulations capture the dominant characteristics of tropical cyclones and are compared to the CAM 5 full physics results for each dynamical core. The research isolates the impact of the physical parameterizations, numerical schemes and uncertainties on the evolution of the cyclone in CAM.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Hart, R. E.

    2013-12-01

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

  5. 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.

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

  6. Tropical cyclone - mature baroclinic wave interaction: Wave activity diagnostic and bifurcation point behaviour

    NASA Astrophysics Data System (ADS)

    Riemer, Michael; Jones, Sarah

    2013-04-01

    Rossby wave trains are fundamental to the synoptic-scale dynamics of the midlatitudes. It is well known that these wave trains play an important role in the development of midlatitude weather systems and associated weather events. One particular process that may significantly modify a Rossby wave train is the interaction with a tropical cyclone undergoing extratropical transition. Previous studies have shown that such an interaction often produces enhanced uncertainty of medium-range weather predictions. Our understanding of the physical processes of this interaction and the causes of the reduced predictability is still incomplete. This presentation will examine an idealized scenario of extratropical transition, in which a tropical cyclone interacts with a mature baroclinic wave. The impact of the tropical cyclone is quantified as a source of wave activity for the upper-level wave pattern using piecewise inversion of potential vorticity complemented by a Helmholtz decomposition and an estimate of diabatic terms. In contrast to many previous studies, a consistent (further) amplification of the mature wave pattern is not diagnosed in this scenario. In fact, the interaction with the tropical cyclone initiates wave breaking and thus a weakening of the wave pattern. The impact on the midlatitude wave is sensitive to the phasing of the wave pattern and the tropical cyclone, as found in previous studies. Sensitivity experiments reveal three distinct scenarios: a no-transition scenario, in which the tropical cyclone passes to the south of the upstream trough, and two scenarios that have been dubbed previously ``northeast'' and ``northwest'' pattern, respectively. Examination of the topology of the quasi-stationary steering flow reveals two bifurcation points that separate the three distinct regimes. Thus, uncertainties in the modification of the midlatitude wave train can be attributed to a large extent to the bifurcation behaviour of the tropical cyclone track.

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

    NASA Astrophysics Data System (ADS)

    Jablonowski, Christiane; Zarzycki, Colin

    2014-05-01

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

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

    E-print Network

    Colorado at Boulder, University of

    to assess the contributions of various meteorological phenomena to the incidence and severity, large-scale flooding of the upper Mississippi river basin. Consequently, there will be differ- ent types that "tropical storm" is a "tropical cyclone" of less than hurricane intensity but with winds of greater than 34

  9. 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

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

    Microsoft Academic Search

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

    2007-01-01

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

  11. 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.

  12. 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.

  13. 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.

  14. Tropical cyclones in enhanced resolution CMIP5 experiments

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  15. Pollution and dust aerosols modulating tropical cyclones intensities

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Daniel; Clavner, Michal; Nirel, Ronit

    2011-10-01

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

  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. Influence of upper ocean stratification interannual variability on tropical cyclones

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  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. An ocean coupling potential intensity index for tropical cyclones

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  20. Mean structure of tropical cyclones making landfall in mainland China

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  1. Convective asymmetries associated with tropical cyclone landfall: ?-plane simulations

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Liang, Xudong

    2010-07-01

    The physical processes associated with changes in the convective structure of an idealized tropical cyclone (TC) during landfall on a beta-plane were studied using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model, version 3 (MM5). The simulation results suggested that the suppression of moisture supply and increased friction acted to enhance the convection from the left and front quadrants of the TC to the front and right of the TC during different periods of landfall. When surface moisture flux was turned off, convection in other parts of the quadrant was clearly suppressed and the total rainfall was reduced. When surface friction was increased, precipitation showed a marked increase after the TC made landfall. Wetter air at low and intermediate levels, and drier air at high levels around the onshore side of the coastline led to a high value of convective available potential energy (CAPE). Consequently, convection was enhanced immediately downstream of this area when the surface moisture flux was cut off. When surface friction was increased, the physical process was similar prior to landfall. After landfall, increased convergence at the onshore side of the land resulted in enhanced convection in front of the TC. Consistent with previous findings, our results suggest that during landfall the TC structure changes from one of thermodynamic symmetry to asymmetry due to differential moisture flux between the land and sea surface. The asymmetry of the thermodynamic structure, which can be explained by the distribution of CAPE, causes an asymmetric rainfall structure.

  2. Tropical cyclone track and genesis forecasting using satellite microwave sounder data

    NASA Technical Reports Server (NTRS)

    Kidder, S. Q.

    1982-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    This paper presents the NOW regional coupled ocean-atmosphere model built from the NEMO ocean and WRF atmospheric numerical models. This model is applied to the tropical Indian Ocean, with the oceanic and atmospheric components sharing a common ¼° horizontal grid. Long experiments are performed over the 1990-2009 period using the Betts-Miller-Janjic (BMJ) and Kain-Fritsch (KF) cumulus parameterizations. Both simulations produce a realistic distribution of seasonal rainfall and a realistic northward seasonal migration of monsoon rainfall over the Indian subcontinent. At subseasonal time scales, the model reasonably reproduces summer monsoon active and break phases, although with underestimated rainfall and surface wind signals. Its relatively high resolution results in realistic spatial and seasonal distributions of tropical cyclones, but it fails to reproduce the strongest observed cyclone categories. At interannual time scales, the model reproduces the observed variability associated with the Indian Ocean Dipole (IOD) and the delayed basin-wide warming/cooling induced by the El Niño Southern Oscillation (ENSO). The timing of IOD occurrence in the model generally matches that of the observed events, confirming the influence of ENSO on the IOD development (through the effect of lateral boundary conditions in our simulations). Although the KF and BMJ simulations share a lot in common, KF strongly overestimates rainfall at all time scales. KF also overestimates the number of simulated cyclones by a factor two, while simulating stronger events (up to 55 m s-1) compared to BMJ (up to 40 m s-1). These results could be related to an overly active cumulus parameterization in KF.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  5. Sudden Tropical Cyclone Track Changes over Western North Pacific: A Composite Study

    NASA Astrophysics Data System (ADS)

    Wu, L.

    2012-12-01

    Large-scale monsoon gyres and the involved tropical cyclone formation over the western North Pacific have been documented in previous studies. This study is aimed to understand how monsoon gyres affect tropical cyclone formation. As the first part of this study, an observational study is conducted on monsoon gyres during the period 2000-2010, with a focus on their structures and the associated tropical cyclone formation. A total of 36 monsoon gyres are identified in May-October during 2000-2010, among which 31 monsoon gyres are accompanied with the formation of 43 tropical cyclones, accounting for 20.3% of the total tropical cyclone formation. Monsoon gyres generally are found on the poleward side of the climatological monsoon trough with a peak occurrence in August-October. Extending about 1000 km outward from the center in at lower levels, the cyclonic circulation of the composited monsoon gyre shrinks with height and is replaced with negative relative vorticity above 200 hPa. The maximum winds of the composited monsoon gyre appear 500-800 km away from the gyre center with a magnitude of 8-13 m s-1 at 850 hPa. In agreement with previous studies, the composited monsoon gyre shows enhanced southwesterly flows and convection on the south-southeast side due to Rossby wave energy dispersion. Most of tropical cyclones associated with monsoon gyres are found to form near the centers of monsoon gyres and the northeast end of the enhanced southwesterly flows, accompanying with weak vertical wind shear.

  6. 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.

  7. 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

  8. 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.

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

    PubMed Central

    Emanuel, Kerry A.

    2013-01-01

    A recently developed technique for simulating large [O(104)] numbers of tropical cyclones in climate states described by global gridded data is applied to simulations of historical and future climate states simulated by six Coupled Model Intercomparison Project 5 (CMIP5) global climate models. Tropical cyclones downscaled from the climate of the period 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

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

    NASA Astrophysics Data System (ADS)

    Krouse, Kyle D.; Sobel, Adam H.

    2010-05-01

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

  11. Understanding the impact of saharan dust aerosols on tropical cyclones

    NASA Astrophysics Data System (ADS)

    Naeger, Aaron

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

  12. Cluster analysis of tropical cyclone tracks in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Ramsay, Hamish A.; Camargo, Suzana J.; Kim, Daehyun

    2012-08-01

    A probabilistic clustering method is used to describe various aspects of tropical cyclone (TC) tracks in the Southern Hemisphere, for the period 1969-2008. A total of 7 clusters are examined: three in the South Indian Ocean, three in the Australian Region, and one in the South Pacific Ocean. Large-scale environmental variables related to TC genesis in each cluster are explored, including sea surface temperature, low-level relative vorticity, deep-layer vertical wind shear, outgoing longwave radiation, El Niño-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO). Composite maps, constructed 2 days prior to genesis, show some of these to be significant precursors to TC formation—most prominently, westerly wind anomalies equatorward of the main development regions. Clusters are also evaluated with respect to their genesis location, seasonality, mean peak intensity, track duration, landfall location, and intensity at landfall. ENSO is found to play a significant role in modulating annual frequency and mean genesis location in three of the seven clusters (two in the South Indian Ocean and one in the Pacific). The ENSO-modulating effect on genesis frequency is caused primarily by changes in low-level zonal flow between the equator and 10°S, and associated relative vorticity changes in the main development regions. ENSO also has a significant effect on mean genesis location in three clusters, with TCs forming further equatorward (poleward) during El Niño (La Niña) in addition to large shifts in mean longitude. The MJO has a strong influence on TC genesis in all clusters, though the amount modulation is found to be sensitive to the definition of the MJO.

  13. Physical and Biological Responses of Forests to Tropical Cyclones Affecting the United States Atlantic Ocean and Gulf of Mexico Coasts

    Microsoft Academic Search

    Pete Bettinger; Jeffrey Hepinstall

    2009-01-01

    Problem Statement: Natural resources within the southern United States have repeatedly been subjected to the impact of tropical cyclones. While the frequency of tropical cyclones hitting either coast varies from year to year, it is crucial for natural resource managers and land owners to be prepared for the damage resulting from such storms. The goal of this review paper is

  14. Analysis and prediction of hazard risks caused by tropical cyclones in Southern China with fuzzy mathematical and grey models

    E-print Network

    Zhang, Da-Lin

    Analysis and prediction of hazard risks caused by tropical cyclones in Southern China with fuzzy 2011 Keywords: Combined weights Fuzzy mathematical models Hazard risk analysis Exceeded probability Tropical cyclones Grey prediction model a b s t r a c t A hazard-risk assessment model and a grey hazard

  15. Tropical Cyclone Activity and Climate Fluctuations Captured by Oxygen Isotopes in Tree-Ring Cellulose From the Southeastern US

    Microsoft Academic Search

    D. L. Miller; C. I. Mora; H. D. Grissino-Mayer; C. J. Mock; M. E. Uhle

    2003-01-01

    Tropical cyclone activity in the Atlantic Ocean and Gulf of Mexico fluctuates on seasonal to century scales. Large climate oscillations, such as the El Nino Southern Oscillation, Atlantic Multidecadal Oscillation, and the Pacific Decadal Oscillation may affect this tropical cyclone activity. To better discern and understand factors influencing long-term trends in hurricane occurrence, proxies are needed that extend the record

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

    E-print Network

    Grissino-Mayer, Henri D.

    A multitree perspective of the tree ring tropical cyclone record from longleaf pine (Pinus; revised 16 February 2011; accepted 3 March 2011; published 21 May 2011. [1] Tree rings afford the temporal. Perfect (2011), A multitree perspective of the tree ring tropical cyclone record from longleaf pine (Pinus

  17. A new paradigm for intensity modification of tropical cyclones: thermodynamic impact of vertical wind shear on the inflow layer

    Microsoft Academic Search

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

    2009-01-01

    An important roadblock to improved intensity forecasts for tropical cyclones (TCs) is our incomplete understanding of the interaction of a TC with the environmental flow. In this paper we re-visit the classical idealised numerical experiment of tropical cyclones (TCs) in vertical wind shear on an f-plane. We employ a set of simplified model physics - a simple bulk aerodynamic boundary

  18. 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

  19. The Tropical Cyclone Modeling Team (TCMT): Evaluation of Experimental Models for Tropical Cyclone Forecasting in Support of the NOAA Hurricane Forecast Improvement Project (HFIP)

    NASA Astrophysics Data System (ADS)

    Kucera, P. A.; Brown, B.; Nance, L. B.; Crosby, K. M.; Williams, C.; Jensen, T.

    2010-12-01

    In 2009, the National Center for Atmospheric Science (NCAR)/Research Applications Laboratory’s (RALs) Joint Numerical Testbed (JNT) Program formed a new entity called the Tropical Cyclone Modeling Team (TCMT). The focus of this team is testing and evaluation of experimental models with the goal of improving tropical cyclone forecasts. Much of this effort is sponsored by NOAA's Hurricane Forecast Improvement Project (HFIP). For HFIP, the TCMT designs model evaluation experiments and provides general testing and evaluation of the various forecast models included in the HFIP annual forecasting demonstrations and retrospective experiments. The TCMT is developing statistical approaches that are appropriate for evaluating a variety of tropical cyclone forecast attributes. These methods include new diagnostic tools to aid, for example, in the evaluation of track and intensity errors, precipitation and tropical cyclone structure forecasts. Currently, the TCMT is conducting an evaluation of a suite of experimental models that are candidates for future inclusion into the operational forecasting system at the National Hurricane Center (NHC). This 2010 retrospective analysis is being conducted using storms observed during the 2008 and 2009 hurricane seasons in the Eastern Pacific and Atlantic basins. The goals of the 2010 retrospective testing are to (1) provide adequate statistics for assessing the skill of the model candidates, (2) help identify modeling systems to could be included in future operational forecast guidance, and (3) provide information that may help to calibrate the multi-model ensemble forecasts. The retrospective testing focused on a representative sample of 27 storms from the 2008 and 2009 hurricane seasons. Four modeling groups participated in the retrospective testing. The models included two configurations of the Weather Research and Forecasting (WRF) model, a new version of the NOAA Geophysical Fluid Dynamic Laboratory’s (GFDL) model, and the Navy’s tropical cyclone model. This presentation will provide an overview of the 2010 retrospective testing, a summary of the differences in track and intensity errors for the comparisons of the individual participating models, and an evaluation of the impact of including the experimental model in the NHC conventional consensus forecast. The presentation will also provide an overview of future plans for the evaluation of tropical cyclone forecasts.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolan L.; Feng, Yang

    2014-05-01

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

  8. 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 ...

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

    NASA Video Gallery

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

  10. Variability in tropical cyclone heat potential over the Southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. Storm-Centered Ensemble Data Assimilation for Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Navarro, Erika L.

    A significant challenge for tropical cyclone ensemble data assimilation is that storm-scale observations tend to make analyses that are more asymmetric than the prior forecasts. Compromised structure and intensity, such as an increase of amplitude across the azimuthal Fourier spectrum, are a routine property of ensemble-based analyses, even with accurate position observations and frequent assimilation. Storm dynamics in subsequent forecasts evolve these states toward axisymmetry, creating difficulty in distinguishing between model-induced and actual storm asymmetries for predictability studies and forecasting. To address this issue, we propose here a novel algorithm using a storm-centered approach. The method is designed for use with existing ensemble filters with little or no modification, facilitating its adoption and maintenance. The algorithm consists of: (1) an analysis of the environment using conventional coordinates, (2) a storm-centered analysis using storm-relative coordinates, and (3) a merged analysis that combines the large-scale and storm-scale fields together at an updated storm location. The storm-centered method is evaluated for two sets of experiments: no-cycling tests of the update step for idealized, three-dimensional storms in radiative--convective equilibrium, and full cycling tests of data assimilation applied shallow-water model for a field of interacting vortices. In both cases results are compared against a control based on a conventional ensemble Kalman filter scheme. Results show that storm-relative assimilation yields vortices that are more symmetric and exhibit finer inner-core structure than for the control, with errors reduced by an order of magnitude as compared to a control with prior spread similar to the National Hurricane Center's 12~h mean track error in 12~h forecasts. Azimuthal Fourier error spectra exhibit much-reduced noise associated with data assimilation as compared to the conventional EnKF scheme. An assessment of the affect of the merge step on balance reveals a similar, balanced trend in free-surface height tendency between the storm-centered and conventional EnKF approaches, with storm-centered values more closely resembling the reference state.

  12. 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, L.; 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.

  13. Cyclone induced Upper Ocean Cooling and Modulation of Surface Winds - A study using satellite data over tropical ocean region

    NASA Astrophysics Data System (ADS)

    Kvs, Badarinath; Kharol, Shailesh Kumar; Dileep, K. P.

    Tropical Cyclones are associated with intense winds, rain, storm surges and variations in cloud patterns. Accurate forecasting of both track and intensity of a tropical cyclone requires thorough understanding of meteorological processes. In this study, we evaluate the relationships between sea-surface temperature (SST) and meteorological parameters over Bay of Bengal region, India using microwave satellite remote sensing data. Most of the cyclones in this region occur during the pre-monsoon period from April-June and are associated with SST greater than 260 C. We have particularly analyzed the data from two recent cyclonic events, Mala that occurred during 24th April 2006 and Tropical Cyclone 01B that occurred during 11th May, 2003. Mala was a very severe cyclonic storm equal to category 4 hurricane on the Saffir-Simpson Hurricane Scale. We used two different remote sensing data sets, the Tropical Rainfall Measurement Mission Sea Surface Temperature (SST) and the NASA QuikSCAT ocean surface wind vectors to characterize the ocean-atmosphere interactions in cold SST regions formed in the trail of the above two cyclone events. Results from the satellite data analysis suggested systematic weakening of wind speed over the cold patch, along the trail of the cyclone. A cooling of around 4 to 5 degrees was observed associated with the passage of cyclone Mala. Wind speed gradually increased from 2 to 9 m/s from the center to the boundary of the cold patch and showed good correlation with SST (r=0.97). These observations have been validated with another cyclone data (Tropical Cyclone 01B) over the Bay of Bengal region that occurred during May 2003. Our results were consistent with the Wallace hypothesis that SST modulates the surface winds via stability. Mechanisms governing SST and wind speed have been highlighted utilizing data from two different tropical cyclone events and remote sensing datasets.

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

    PubMed

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

    2013-09-17

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

  15. 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

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Chen, Buo-Fu; Lee, Cheng-Shang

    2013-04-01

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

  18. 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.

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

    E-print Network

    Texas at Austin. University of

    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

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

    E-print Network

    Maloney, Eric

    The Madden-Julian Oscillation, Barotropic Dynamics, and North Pacific Tropical Cyclone Formation the 850mb flow is used to investigate the relationship between wind variations associated with the Madden-Julian eddies. The eddies that dominate the observed correlations are heavily modified by convection

  1. 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

  2. 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

  3. Use of cloud radars and radiometers for tropical cyclone intensity estimation

    Microsoft Academic Search

    Valerie Wong; Kerry Emanuel

    2007-01-01

    Tropical cyclone intensity is shown to be proportional to the difference between the moist static energy of the eyewall and that of the undisturbed environment, and to the difference between the absolute temperatures of the boundary layer and of the storm top. Measurements of the radial gradient of cloud top altitude and temperature from the eyewall to the outer region

  4. Remote forcing of water levels by tropical cyclones in southwest Australia

    Microsoft Academic Search

    Matthew Eliot; Charitha Pattiaratchi

    2010-01-01

    Tropical cyclones (termed hurricanes and typhoons in other regions), are extreme events associated with strong winds, torrential rain and storm surges (in coastal areas) and cause extensive damage as a result of strong winds and flooding (caused by either heavy rainfall or ocean storm surges) in the immediate area of impact. The eastern Indian Ocean, particularly in the northwest region

  5. Thoughts on whether government should steer a tropical cyclone if it could

    Microsoft Academic Search

    Kelly Klima; M. Granger Morgan

    2012-01-01

    Previous work suggests if it were possible to lower sea-surface temperature using wind-wave pumps, it would sometime make sense to try to reduce the wind speed of a tropical cyclone (TC) that is likely to make landfall. While currently there is no plausible strategy to steer a TC, suppose that TC landfall location could be altered and subsequent damages perhaps

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

    E-print Network

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

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

    E-print Network

    Wind Farms in Regions Exposed to Tropical Cyclones Niels-Erik Clausen1 , niels Energy A/S, A.C. Meyers Vænge 9, DK-2450 Copenhagen SV, Denmark, Phone +45 44 80 65 71 3 Tripod Wind 6001 Summary The present paper analyses the design basis of wind farms to be established in regions

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

    Microsoft Academic Search

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

    2005-01-01

    Radar structures of one mesocyclone and one mesocirculation (the term mesocirculation refers to a class of rotating updrafts, which may or may not be as spatially and temporally large as a typical mesocyclone) that developed a total of four tornadoes in association with Tropical Cyclone (TC) Frances 1998 are presented. One tornado developed within an inner rainband near the time

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

    E-print Network

    Schubert, Wayne H.

    Upper Oceanic Energy Response to Tropical Cyclone Passage JOHN A. KNAFF AND MARK DEMARIA NOAA is investigated using a 6-yr daily record of data-driven analyses of two measures of upper ocean energy content information and the upper ocean response. Upper oceanic energy decreases in these metrics are shown to persist

  10. A Diagnostic Study on the Statistical Predictability of Tropical Cyclone Motion

    Microsoft Academic Search

    Charles J. Neumann; John R. Hope

    1973-01-01

    Statistical tropical cyclone prediction systems typically fall into one of three categories: 1) those using meteorological predictors derived from observed synoptic data; 2) those using purely empirical predictors such as climatology, present motion, past motion, analogs, etc.; and 3) those using combinations of both synoptic and empirical predictors. The variance-reducing potential of each of these prediction systems on given acts

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

    E-print Network

    Sensitivity of Ocean-Atmosphere Coupled Models to the Coupling Method : Example of Tropical Cyclone, the sensitivity of Atmospheric and Oceanic Coupled Models (AOCMs) to the coupling method is investigated. We of a mesoscale atmospheric model (WRF) coupled with a regional oceanic model (ROMS) to simulate the genesis

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  13. 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.

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

    Microsoft Academic Search

    Mark Demaria; John Kaplan

    1994-01-01

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

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

    Microsoft Academic Search

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

    2004-01-01

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

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

    Microsoft Academic Search

    D. Mardhekar

    2010-01-01

    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

  17. Retrieval of Hydrometeor Profiles in Tropical Cyclones and Convection from Combined Radar and Radiometer Observations

    E-print Network

    Jiang, Haiyan

    and Radiometer Observations HAIYAN JIANG* AND EDWARD J. ZIPSER Department of Meteorology, University of Utah Radiometer data in tropical cyclones and convection. An indirect validation is performed by com- paring broadly into radar-only, radiometer-only, and combined radar­radiometer approaches based

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

    Microsoft Academic Search

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

    2002-01-01

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

  19. Influence of environmental moisture on TRMM-derived tropical cyclone precipitation over land and ocean

    E-print Network

    Jiang, Haiyan

    , HMC, or OSF values are associated with higher azimuthally averaged rain rates. Over land distributions of azimuthally averaged TC rain rates derived from the TRMM Microwave Imager [Lonfat et al., 2004 model (R- CLIPER) used operationally in the Atlantic Ocean basin mainly utilizes tropical cyclone (TC

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

    Microsoft Academic Search

    Y. Wang; C.-C. Wu

    2004-01-01

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

  1. 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

  2. Study of tropical cyclone motion with a coupled hurricane-ocean model

    Microsoft Academic Search

    Liguang Wu

    1999-01-01

    The physical mechanism of baroclinic tropical cyclone (TC) motion is studied through use of a high resolution model. The effect of hurricane-ocean interaction is incorporated by coupling the atmospheric model to an intermediate ocean model, which can produce the major features caused by the hurricane-ocean interaction, including cooling, deepening and the induced currents of the ocean mixed layer. In order

  3. 9.6 NONSUPERCELL TROPICAL CYCLONE TORNADOES: DOCUMENTATION, CLASSIFICATION AND UNCERTAINTIES

    E-print Network

    a pronounced climatological tendency for TC tornadoes to occur generally north through southeast of center (e9.6 NONSUPERCELL TROPICAL CYCLONE TORNADOES: DOCUMENTATION, CLASSIFICATION AND UNCERTAINTIES Roger in the operational prediction of tornado threat, regardless of whether the favorable environment results from

  4. Tornadic Behavior Related to Land-Falling Tropical Cyclones in the United States

    Microsoft Academic Search

    Jaclyn M Ritzman; D S Arndt; M C Kruk

    2011-01-01

    The 2004 and 2005 North Atlantic hurricane seasons were among the most active and economically devastating for the United States, during which 18 tropical cyclones (TCs) made landfall. These TCs were analyzed using the International Best Tracks Archive for Climate Stewardship (IBTrACS) and Local Storm Reports (LSR) datasets to determine whether they produced tornadoes within a preferred quadrant and distance

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

    PubMed Central

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

    2014-01-01

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

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

    E-print Network

    Li, Tim

    development characteristics: 1) a transition from non-organized cumulus-scale (~5 km) convective cells1 Tropical cyclone genesis efficiency: mid-level versus bottom vortex Xuyang Ge and Tim Li into an organized meso-vortex-scale (~50-100 km) system through upscale cascade processes, 2) the establishment

  7. Multiformity of the tropical cyclone wind-pressure relationship in the western North Pacific: discrepancies among four best-track archives

    NASA Astrophysics Data System (ADS)

    Kueh, Mien-Tze

    2012-06-01

    The reliability of tropical cyclone intensity estimates for the western North Pacific is assessed in the context of wind-pressure relationships. Four best-track datasets compiled in the International Best Track Archive for Climate Stewardship (IBTrACS) are compared to assess the data consistency. Over the past 20 yr period (1991-2010), apparent interagency discrepancies in the archived tropical cyclone intensities are found. Heavy reliance upon operational wind-pressure relationships may reduce subjective biases at the cost of potential loss of tropical cyclone natural variability. Given that the intercomparisons are performed based upon a set of identical tropical cyclones, the differences in operational wind-pressure relationships and in the mapping of satellite tropical cyclone intensity classification for these relationships are presumably critical causes of the interagency discrepancies. This result calls for imperative refinement of current satellite-based tropical cyclone intensity estimates and reanalysis of historical tropical cyclone best-track archives for the basin.

  8. 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.

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  11. Initial Condition Sensitivity and Predictability of Tropical Cyclone Development and Intensification

    NASA Astrophysics Data System (ADS)

    Doyle, J.; Amerault, C. M.; Moskaitis, J.; Reinecke, A.; Reynolds, C. A.

    2012-12-01

    It has been suggested in a number of previous studies that the development of tropical cyclones and intensification may be sensitive to aspects of large-scale forcing, as well as internal mesoscale dynamics. In this study, we explore the hypothesis that the development and intensification of tropical cyclones are sensitive to small perturbations to the basic properties of the background state through organized mesoscale convection and synoptic-scale forcing. The recently developed adjoint and tangent linear models for the atmospheric portion of the nonhydrostatic Coupled Atmosphere/Ocean Mesoscale Prediction System (COAMPS) are used to explore the mesoscale sensitivity of tropical cyclone development and subsequent intensification (or lack of) to the initial state. A unique aspect of this system is that an exact adjoint to the explicit microphysics has been developed. The forward, adjoint and tangent linear models are applied at horizontal resolutions ranging from 10-40 km and are used to explore predictability issues for several tropical cyclones and non-developing storms. We will focus on the Western Pacific basin during the THORPEX Pacific Asian Regional Campaign (T-PARC) and the ONR Tropical Cyclone Structure-08 (TCS08) experiments (fall 2008) and the Impact of Typhoons on the Ocean in the Pacific (ITOP) (fall 2010). Some preliminary results from the W. Atlantic basin will be presented based on the first field phase of the NASA Hurricane and Severe Storm Sentinel (HS3), planned for the fall 2012. The adjoint results indicate that the short term (6-24-h) forecasts of tropical cyclone intensity (e.g., kinetic energy) are very sensitive to the initial state. The adjoint-based sensitivity fields indicate highly structured patterns in the wind, thermal, moisture, and microphysical fields that project on to the model simulated deep convection, which ultimately influences the intensification rate. The highest-resolution adjoint simulations (~10 km grid increment) indicate that the most efficient intensification is through low- and mid-level moistening and heating in banded regions that are coincident with vorticity maxima in the initial state. Optimal adjoint perturbations exhibit rapid growth for a developing case, Typhoon Nuri, and only modest growth for a nondeveloping case TCS025. The adjoint results suggest that Nuri was near the threshold for development, indicative of low predictability. The low-level sensitivity maximum and tendency for optimal perturbation growth to extend vertically through the troposphere are consistent with a "bottom-up" development process of TC development, although a secondary mid-level sensitivity maximum is present as well. Growth originates at small scales and projects on to the scale of the vortex, a manifestation of perturbations that project onto organized convection embedded in regions of cyclonic vorticity.

  12. 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.

  13. 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.

  14. Stable isotope anatomy of tropical cyclone ita, north-eastern australia, april 2014.

    PubMed

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

    2015-01-01

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

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  17. Multi-year forecast of Atlantic tropical cyclone activity using EC-Earth

    NASA Astrophysics Data System (ADS)

    Caron, L.-P.; Jones, C. G.; Doblas-Reyes, F. J.; Caian, M.

    2012-04-01

    Seasonal forecasts of Atlantic hurricane activity are now routinely performed by various groups and have become relatively successful at forecasting basin wide activity a few months before the official start of a hurricane season. Part of the skill in predicting the level of tropical cyclone activity for a given season comes from the ability to predict the behaviour of ENSO, which strongly impacts (through teleconnections) hurricane formation over the Atlantic. Over the same basin, the ~100 years of available hurricane records also show variations at the decadal timescale. This decadal fluctuation appears linked to an oscillation in North Atlantic sea surface temperatures (SSTs). Coined the Atlantic Multi-decadal Oscillation (AMO), a successful multi-year forecast of this oscillation offers the potential to produce a skillful multi-year forecast of hurricane activity. Such forecast could help mitigate against (potentially huge) hurricane-related losses through improved preparedness and improved insurance schemes. Using EC-Earth, a coupled global atmosphere-ocean model, we perform a series of ensemble decadal re-forecasts at 5 year intervals between the 1965-2005 period and investigate the ability of these re-forecasts at capturing observed variations in North Atlantic SSTs (in essence, the AMO) as well as other large-scale fields known to impact cyclogenesis. We also use an automated procedure to track the tropical cyclones produced in these re-forecasts, which then allows direct comparison with the actual number of tropical cyclones that formed over the equivalent period. Preliminary analysis shows that EC-Earth re-forecasts manage to capture variations in large-scale fields relatively well, especially variations in the AMO, which suggests a potential for skillful multi-year forecast of Atlantic tropical cyclones. However, direct comparison of simulated and observed TC numbers does not offer the same level of skill. Tropical cyclone numbers in the re-forecasts are biased low, and this appears to result not only from the low-resolution of the simulation (~1.125°), but also from a drift in simulated SSTs. This drift brings surface temperature below the 26°C threshold required for tropical cyclone formation, effectively shutting down storm formation over large parts of the tropical Atlantic. Potential solutions to circumvent these limitations are currently being considered and will be discussed.

  18. Australian region tropical cyclones: Influence of environment at different scales

    NASA Astrophysics Data System (ADS)

    Ramsay, Hamish Andrew

    This dissertation explores the influence of environmental factors on a variety of spatial and temporal scales on tropical cyclones (TCs) in the Australian region. Chapter 1 provides the motivation for the work presented, and leads into a discussion on the current state of knowledge of large-scale factors affecting the interannual variability of TCs in each of the seven global TC basins (Chapter 2). Chapter 3 is an investigation of the role of large-scale environmental factors, notably sea surface temperature (SST), low-level relative vorticity, and deep tropospheric vertical wind shear, for the interannual variability of November-April tropical TC activity in the Australian region. Extensive correlation analyses were carried out between TC frequency and intensity and the above-mentioned large-scale parameters, using TC data for 1970-2006 from the official Australian TC data set. Large correlations were found between the seasonal number of TCs and SST in the Nino 3.4 and Nino 4 regions. These correlations were greatest (-0.73) during the August-October period, immediately preceding the Australian TC season. The correlations remain almost unchanged for the July-September period and therefore can be viewed as potential seasonal predictors of the forthcoming TC season. In contrast, only weak correlations (<+0.37) were found with the local SST in the region north of Australia where many TCs originate; these were reduced almost to zero when the ENSO component of the SST was removed by partial correlation analysis. The annual frequency of TCs was strongly correlated with 850-hPa relative vorticity and vertical shear of the zonal wind over the main TC genesis areas of the Australian region. A Principal Component Analysis of the SST data set revealed two main modes of Pacific Ocean SST variability that match very closely with the basin-wide patterns of correlations between SST and TC frequencies. It was also found that the above-mentioned large correlations could be increased markedly (e.g. from -0.73 to -0.80 for the August-October period) by a weighted combination of SST time series from weakly correlated regions. When only the eastern region subset of the Australian TC data set was considered (Chapter 4), including the annual number of landfalling TCs in the northeastern state of Queensland, the correlations between TC number and ENSO decreased substantially. These correlations were reduced to less than +0.1 during the warm phase of Interdecadal Pacific Oscillation from 1979-1998, suggesting that the relationship between TC activity and ENSO fluctuates on interdecadal time scales. The number of landfalling TCs was highly correlated (+0.68) with total number of TCs forming in the eastern region each year. The interaction between complex terrain and a landfalling TC over northeastern Australia is investigated in Chapter 5 using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5). Severe TC Larry (March 2006) made landfall over an area of steep coastal orography and caused extensive damage. The damage pattern suggested that the mountainous terrain had a large influence on the TC wind field, with highly variable damage across relatively small distances. The major aims in this study were to reproduce the observed features of TC Larry, including track, intensity, speed of movement, size, decay rate, and the three-dimensional wind field, using realistic high-resolution terrain data and a nested grid with a horizontal spacing of 1 km for the finest domain (referred to as CTRL), and to assess how the above parameters change when the terrain height is set to zero (NOTOPOG). The TC track for CTRL, including the timing and location of landfall, was in close agreement with observation, with the model eye overlapping the location of the observed eye at landfall. Setting the terrain height to zero resulted in a more southerly track and a more intense storm at landfall. The orography in CTRL had a large impact on the TC's 3-D wind field, particularly in the boundary

  19. Dynamical effects of environmental vertical wind shear on tropical cyclone motion, structure, and intensity

    NASA Astrophysics Data System (ADS)

    Zheng, X.; Duan, Y. H.; Yu, H.

    2007-08-01

    A series of numerical experiments on an f plane are conducted using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model, version 3 (MM5) to investigate how environmental vertical wind shear affects the motion, structure, and intensity of a tropical cyclone. The results show that a tropical cyclone has a motion component perpendicular to the vertical shear vector, first to the right of the shear and then to the left. An initially axisymmetric, upright tropical cyclone vortex develops a downshear tilt and wavenumber-one asymmetry when embedded in environmental vertical wind shear. In both small-moderate shears, a storm weakens slightly compared to that in a quiescent environment. The circulation centers between 300 hPa and the surface varies from 20 km to over 80 km. The secondary circulation becomes quite asymmetric about the surface cyclone center. As a result, convection on the upshear-right quadrant diminishes, limiting the upward heat transport in the eyewall and thus lowering the warm core and leading to a weakening of the storm. In strong vertical shear (above 12 m s-1), the vertical tilt exceeds 160 km in 48 h of simulation and the secondary circulation on the upshear side is completely destroyed with low-level outflow. The axisymmetric component of eyewall convection weakens remarkably and becomes much less penetrative. As a result, the warm core becomes weak and appears at lower levels and the storm weakens rapidly accordingly. This up-down weakening mechanism discussed in this study is different from those previously discussed. It emphasizes the penetrative role of eyewall convection in transporting heat from the ocean to the mid-upper troposphere, maintaining the warm core structure of the tropical cyclone. The vertical shear is found negative to eyewall penetrative convection.

  20. A~characterization of thermal structure and conditions for overshooting of tropical and extratropical cyclones with GPS radio occultation

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Steiner, A. K.; Kirchengast, G.; Rieckh, T.

    2014-11-01

    The thermal structure of Tropical Cyclones (TCs) in different ocean basins is studied using Global Positioning System (GPS) Radio Occultation (RO) measurements co-located with TCs' best tracks. The objective of this work is to understand the mutual influence of TCs and atmospheric parameters in different regions. We selected more than 20 000 GPS RO profiles co-located with TCs in a time window of 6 h and space window of 600 km from the TC center in the period 2001-2012 and classified them by intensity of the cyclone and by ocean basin. The results show that tropical cyclones have different characteristics depending on the basin, which affects the cloud top altitude, and the TC thermal structure, which usually shows a negative temperature anomaly near the cloud top altitude. In the Northern Hemisphere ocean basins, the temperature anomaly becomes positive above the cloud top, while in the Southern Hemisphere ocean basins, it stays negative up to about 25 km of altitude. Furthermore, in the Southern Hemisphere the storms reach higher cloud top altitudes than in the Northern Hemisphere ocean basins, indicating that possible overshootings overpass the climatological tropopause more deeply at extratropical latitudes. The comparison of the TC thermal structure with the respective monthly mean tropopause altitude allows a detailed analysis of the probability for possible overshooting. While the co-locations between GPS ROs and TC tracks are well distributed in all the ocean basins, conditions for possible overshootings are found to be more frequent in the Southern Hemisphere basins and in the North Indian ocean basin. However the number of possible overshootings for high intensities (i.e. TC categories 1-5) is highest in the West Pacific ocean basin.

  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. 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.

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

    E-print Network

    Millier, Vicki Anne

    1989-01-01

    ' the tropopause play crucial roles in tropical cyclone genesis. Gray (1975) later added two additional parameters related to tropical genesis; namely, high mid-level relative humidity and a strong vertical equivalent potential temperature gradient. McBride... developing cloud cluster was approximately twice as large as observed with non-developing cloud clusters. McBride and Zehr also determined that cyclone genesis occurred under conditions of zero vertical wind shear near the system center and that large...

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

    E-print Network

    Briggs, W M

    2007-01-01

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

  5. Xynthia: analysis of an exceptional extra-tropical cyclone

    NASA Astrophysics Data System (ADS)

    Ludwig, P.; Yuen, D.; Born, K.; Pinto, J. G.; Drinka, R.

    2012-04-01

    Between end of February and early March, winter storm Xynthia has affected South Western Europe causing storm damage and flash floods along the Breton coast. The uniqueness of this storm refers to its path and the area of origin, being far southward of the usual North Atlantic storm track. In order to understand the course of the event, the storm development is first analysed by means of ERA-Interim data. An interesting feature is that Xynthia did not cross the polar jet. In fact, the existing split jet structure was responsible for enduring upper level divergence in the vicinity of the cyclone. The southerly area of origin (30N) raises the question to what extent latent heat release (LHR) contributes to the deepening and evolution of Xynthia. Therefore, sensitivity studies with the regional model COSMO-CLM have been carried to verify the amount LHR has on the cyclone development. First, a control simulation covering broad areas of the North Atlantic Ocean with a horizontal resolution of 0.22° shows the development of the storm in very good agreement with the development represented in the reanalysis data. In different sensitivity studies, the influence of LHR is examined. In a first approach, the sea surface temperature (SST) in the initial model fields was reduced in steps of 1K to a maximum decrease of 5K compared to the original SST field. The lowering of the SST was implemented only in the model area where Xynthia underwent massive deepening. The results show that the minimum core pressure remains about 10hPa higher than in the control simulation, while dynamical aspects like jet configuration did not change significantly. Another approach to quantify the amount of LHR on cyclone development is to disable the temperature increment due to latent heat effects. Finally, the energetics are examined to provide information about the environmental energy transfers being accountable for the evolution of the storm.

  6. 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.

  7. 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.

  8. On the potential use of satellite sounder data in forecasting tropical cyclone motion

    NASA Technical Reports Server (NTRS)

    Kidder, S. Q.; Shyu, K.

    1984-01-01

    Although many prediction schemes are available, tropical cyclone track forecast errors are still unacceptably large. A primary difficulty is that tropical cyclones and their environments are poorly observed by conventional data networks. Satellite sounders, however, routinely provide numerous observations near these storms. Mean layer temperatures from the Scanning Microwave Spectrometer (SCAMS) on board the Nimbus-6 satellite are decomposed using empirical orthogonal functions, and the expansion coefficients are related to deviations from persistence track forecasts. Based on multiple correlation coefficients it appears that upper-level (250-100 mb) temperatures contain significant information about the right-angle error of the persistence forecast location. Temperatures from the 1000-500 mb layer seemed to contain little forecast information. Implications of these results for further work are offered.

  9. Tropical Cyclone Track Forecasting Using Optimized Consensus in the Western North Pacific

    NASA Astrophysics Data System (ADS)

    Jun, S.; LEE, W.; Byun, K.; Chang, K.; Lee, J.

    2013-12-01

    This study investigates an optimized consensus method using superensemble, which had the highest skill for 2012 tropical cyclone forecast in NHC, to provide good guidance to forecasters. The superensemble forecast is partitioned into a training phase and forecast phase. In the training phase, weights and bias estimation for the models are calculated on the basis of past forecasts via linear regression. Each forecasted track (latitude, longitude) per forecast period (24h, 48h, 72h, etc.) is obtained by the regression coefficients optimized in the past 2-year training period. We used the KMA (Korea Meteorological Administration) analysis data as the reference value and model (ECMWF, GFS, etc.) forecast data over the western North Pacific during 2011-2013 to verify the superensemble forecast results. The optimized consensus track forecast method, e.g., the monthly weighting, typhoon track classification, has been tested for tropical cyclones in 2013.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    Microsoft Academic Search

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  15. The Effect of Internally Generated Inner-Core Asymmetries on Tropical Cyclone Potential Intensity

    Microsoft Academic Search

    Bo Yang; Yuqing Wang; Bin Wang

    2007-01-01

    In a quiescent environment on an f plane, the internal dynamic processes of a tropical cyclone (TC) can generate axially asymmetric circulations (asymmetries) in its inner-core region. The present study investi- gates how these inner-core asymmetries affect TC intensity. For this purpose, a three-dimensional (3D) TC model and its axisymmetric (2D) version were used. Both have identical model vertical structure

  16. Tropical cyclones in the SW Indian Ocean. Part 1: inter-annual variability and statistical prediction

    Microsoft Academic Search

    Denis S. Chang-Seng; Mark R. Jury

    2010-01-01

    The southwestern Indian Ocean (SWIO) is characterized by significant climate variability and frequent tropical cyclones (TC).\\u000a Year-to-year fluctuations of TC and associated oceanic and atmospheric fields in the period 1961–2002 are studied with reanalysis\\u000a data as composites and cross-correlations, with wavelet filtering and cross-modulus analysis, and by hovmoller analysis and\\u000a multi-variate statistical modeling. Observational limitations in the early part of

  17. Application of scale-selective data assimilation to tropical cyclone track simulation

    Microsoft Academic Search

    Lian Xie; Bin Liu; Shiqiu Peng

    2010-01-01

    Tropical cyclone track is strongly controlled by the large-scale environmental circulation. In limited-area models (LAMs) driven by global analyses or forecasts through a conventional lateral boundary nesting approach, the global analyses are often distorted by the use of “sponge zone” or interpolation when they are passed into the LAM. In this study, a dynamical downscaling approach based on scale-selective data

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  19. Horizontal vorticity redistribution and vortex alignment in developing and mature tropical cyclones

    Microsoft Academic Search

    Paul David Reasor

    2000-01-01

    The three-dimensional redistribution of vorticity within a vortex is examined here in the context of tropical cyclone (TC) structure and intensity change. Aspects of the horizontal vorticity mixing dynamics are first presented in a novel analysis of high temporal resolution wind fields derived from airborne dual-Doppler observations of Hurricane Olivia (1994). Seven consecutive composites of Olivia's wind field with 30-min

  20. Linking Tropical Cyclone Number Over the Western North Pacific with Sea Surface Temperatures

    Microsoft Academic Search

    Chongjian Liu; Liping Ma; Ying Liu; Zhexian Luo; Xiaotu Lei; Xiaogang Zhou; Donghai Wang; Hui Xu

    \\u000a The analyses based on the observational data show that the tropical cyclone (TC) numbers tend to become decreasing over some\\u000a oceanic basins during the recent multiple decades despite a rise in their sea surface temperatures (SSTs). A methodology of\\u000a understanding the mechanism responsible for such seemingly counter intuitive phenomena is suggested in this chapter and thus\\u000a the causality between the

  1. A GCM investigation of global warming impacts relevant to tropical cyclone genesis

    Microsoft Academic Search

    Leonard M. Druyan; Patrick Lonergan; Timothy Eichler

    1999-01-01

    Two approaches that consider how greenhouse warming might impact the frequency of tropical cyclone (TC) genesis are explored. Results are based on GCM experiments with the q-flux version global climate model of the NASA\\/Goddard Institute for Space Studies (GISS); one set representing contemporary atmospheric concentrations of CO2, contrasting with the second set representing the global climate in double CO2 equilibrium.

  2. 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.

  3. Variable-resolution frameworks for the simulation of tropical cyclones in global atmospheric general circulation models

    NASA Astrophysics Data System (ADS)

    Zarzycki, Colin

    The ability of atmospheric General Circulation Models (GCMs) to resolve tropical cyclones in the climate system has traditionally been difficult. The challenges include adequately capturing storms which are small in size relative to model grids and the fact that key thermodynamic processes require a significant level of parameterization. At traditional GCM grid spacings of 50-300 km tropical cyclones are severely under-resolved, if not completely unresolved. This thesis 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 Department of Energy/National Center for Atmospheric Research (DoE/NCAR) Community Atmosphere Model's (CAM) Spectral Element (SE) dynamical core. Using an idealized tropical cyclone test, variable-resolution meshes are shown to significantly lessen computational requirements in regional GCM studies. Furthermore, the tropical cyclone simulations are free of spurious numerical errors at the resolution interfaces. Utilizing aquaplanet simulations as an intermediate test between idealized simulations and fully-coupled climate model runs, climate statistics within refined patches are shown to be well-matched to globally-uniform simulations of the same grid spacing. Facets of the CAM version 4 (CAM4) subgrid physical parameterizations are likely too scale sensitive for variable-resolution applications, but the newer CAM5 package is vastly improved in performance at multiple grid spacings. Multi-decadal simulations following 'Atmospheric Model Intercomparison Project' protocols have been conducted with variable-resolution grids. Climate statistics produced using ocean-centered, variable-resolution nests are almost identical to those from "unrefined" simulations using globally-uniform grids. Regional climatology is improved by refinement due to the better representation of topography. Lastly, tropical cyclone structure, intensity, and interannual variability in the Atlantic Ocean are all significantly improved with the use of variable-resolution grids. These attributes are well-matched to other modeling studies at similar horizontal resolutions while only requiring a fraction of the computational cost, highlighting the potential of using variable-resolution GCMs to simulate small-scale phenomena.

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

    PubMed

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

    2014-03-17

    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 ?(18) O values?tropical depressions bring large rains (>50?mm) at least once every 2 to 3 years, and along the Pacific coast between Jalisco and Oaxaca. PMID:24635484

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  6. 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.

  7. Intensification of premonsoon tropical cyclones in the Bay of Bengal and its impacts on Myanmar

    NASA Astrophysics Data System (ADS)

    Wang, Shih-Yu; Buckley, Brendan M.; Yoon, Jin-Ho; Fosu, Boniface

    2013-05-01

    analyze multiple global reanalysis and precipitation datasets in order to explain the dynamic mechanisms that lead to an observed intensification of the monsoon trough and associated tropical cyclone (TC) activity over the Bay of Bengal (BOB) during the premonsoon month of May. We find that post-1979 increases in both premonsoon precipitation and TC intensity are a result of enhanced large-scale monsoon circulation, characterized by lower-level cyclonic and upper-level anticyclonic anomalies. Such circulation anomalies are manifest of the tropospheric expansion that is caused by regional warming. The deepened monsoon trough in the BOB not only affects TC frequency and timing, but also acts to direct more cyclones towards Myanmar. We propose that increasing sea surface temperature in the BOB has contributed to an increase in cyclone intensity. Our analyses of the Community Earth System Model single-forcing experiments suggest that tropospheric warming and a deepening of the monsoon trough can be explained by two discreet anthropogenic causes—an increase in absorption due to aerosol loading and an increase in the land-ocean thermal contrast that results from increased greenhouse gases. The ensuing circulation changes provide favorable conditions for TCs to grow and to track eastward towards Myanmar.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  10. 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

  11. 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.

  12. Pattern recognition analysis of satellite data for tropical cyclone motion and intensity forecasts

    NASA Technical Reports Server (NTRS)

    Hunter, Herbert; Nunez, Edwin; Barker, Llyle; Rodgers, ED

    1986-01-01

    An objective empirical analysis technique is employed to investigate the extent to which satellite-obtained measurements (GOES IR and TOVS data) of a tropical cyclone and its environment can be used to predict cyclone motion. The paper describes the procedure used to process the satellite derived data in order to optimize their possible predictive value, the technique used in developing the regression algorithms, and the results of testing these algorithms using the Lachenbrach and Mickey (1968) procedure. The data were examined alone and in conjunction with available nonsatellite climatological and persistence variables for each storm. These predictors are similar to those used in the National Hurricane Center (NHC) CLIPPER model. The performances obtained using the Nichols Research Corporation CLIPPER model and the NHC CLIPPER model are compared, using homogeneous data sets for the comparisons. Major differences in results were found to be related to differences in the models.

  13. A simple model for post-landfall intensity changes of tropical cyclone over India, Bangladesh and Myanmar coasts

    NASA Astrophysics Data System (ADS)

    Kishtawal, C. M.; Shah, Shivani; Chaurasia, Sashmita; Jaiswal, Neeru

    2013-08-01

    Using JTWC (Joint Typhoon Warning Center) best track analysis data for the Indian Ocean cyclones, we developed an empirical equation for prediction of maximum surface wind speed of tropical cyclones during first 6-12 hours of landfall along the coastline of Indian subcontinent. A non-linear data fitting approach, the Genetic Algorithm, has been used to develop the above empirical equation using data for 74 tropical cyclones that made landfall on the coasts of India, Bangladesh and Myanmar during the period 1978-2011. For an out of sample validation test, the mean absolute error of the prediction was found to be 5.2 kt, and a correlation of 0.97. Our analysis indicates that time-integration of land area intercepted by cyclones during the landfall is a better predictor of post-landfall intensity compared to post-landfall time span. This approach also helps to tackle the complexity of coastline geometry of Indian subcontinent area.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    Microsoft Academic Search

    Alice Favre; Alexander Gershunov

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Molinari, John; Dodge, Peter; Vollaro, David; Corbosiero, Kristen L.; Marks, Frank, Jr.

    2006-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850 200-hPa vertical wind shear of 12 13 m s-1 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 3 h earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify.Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical-shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast.

  17. 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.

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. 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.

  2. The impacts of altered tropical cyclone activity on climate mitigation strategies

    NASA Astrophysics Data System (ADS)

    Fisk, J. P.; Hurtt, G. C.; LePage, Y.; Patel, P.; Chini, L. P.; Thomson, A. M.; Clarke, L.; Calvin, K. V.; Wise, M.; Chambers, J. Q.; Negron Juarez, R. I.

    2012-12-01

    There is growing evidence that anthropogenic climate change may alter patterns of tropical cyclone frequency, intensity and spatial distribution, which in turn will alter the carbon balance of terrestrial systems in the large regions impacted by these storms. Recent studies project up to a doubling of major storms (Saffir-Simpson Scale 3-5) over the next century. Single large storms have been shown to be capable of causing committed carbon emissions equivalent to the annual U.S. carbon sink. These changes have the potential to affect climate mitigation strategies, most of which rely on maintaining or enhancing the terrestrial carbon sink to restrain the accumulation of atmospheric greenhouse gases. Altered patterns of disturbances and the resulting changes to the carbon balance of terrestrial systems could impact the magnitude of emissions to mitigate, the economic value of ecosystem carbon storage, and thus future land-use patterns, food prices and energy technology. Here we investigate the potential consequences of altered tropical cyclone activity on climate mitigation strategies using a fully integrated model (iED) that links advanced ecological and socio-economic models. The model combines the regional integrated assessment algorithms of the Global Change Assessment Model (GCAM), with the climate- sensitive ecosystem and carbon modeling in the Ecosystem Demography (ED) model, and the land-use mapping algorithms of the Global Land-use Model (GLM). We explore a range of scenarios of altered future tropical cyclone frequency, intensity and spatial pattern, the resulting effects on the terrestrial carbon balance, and the coupled effects on the food and energy sector under a range of future climate mitigation goals.

  3. A multiply nested, movable mesh, fully compressible, nonhydrostatic tropical cyclone model – TCM4: Model description and development of asymmetries without explicit asymmetric forcing

    Microsoft Academic Search

    Y. Wang

    2007-01-01

    Summary  A newly developed, multiply nested, movable mesh, fully compressible, nonhydrostatic tropical cyclone model – TCM4 is documented\\u000a and used to investigate how the asymmetric structure develops in an initially axisymmetric tropical cyclone without any explicit\\u000a asymmetric forcing. For this purpose, the model is configured on an f-plane and initialized with an axisymmetric cyclonic vortex in a quiescent environment with a

  4. Idealized tropical cyclone simulations of intermediate complexity: A test case for AGCMs

    NASA Astrophysics Data System (ADS)

    Reed, Kevin A.; Jablonowski, Christiane

    2012-04-01

    The paper introduces a moist, deterministic test case of intermediate complexity for Atmospheric General Circulation Models (AGCMs). We suggest pairing an AGCM dynamical core with simple physical parameterizations to test the evolution of a single, idealized, initially weak vortex into a tropical cyclone. The initial conditions are based on an initial vortex seed that is in gradient-wind and hydrostatic balance. The suggested “simple-physics” package consists of parameterizations of bulk aerodynamic surface fluxes for moisture, sensible heat and momentum, boundary layer diffusion, and large-scale condensation. Such a configuration includes the important driving mechanisms for tropical cyclones, and leads to a rapid intensification of the initial vortex over a forecast period of ten days. The simple-physics test paradigm is not limited to tropical cyclones, and can be universally applied to other flow fields. The physical parameterizations are described in detail to foster model intercomparisons. The characteristics of the intermediate-complexity test case are demonstrated with the help of four hydrostatic dynamical cores that are part of the Community Atmosphere Model version 5 (CAM 5) developed at the National Center for Atmospheric Research (NCAR). In particular, these are the Finite-Volume, Spectral Element, and spectral transform Eulerian and semi-Lagrangian dynamical cores that are coupled to the simple-physics suite. The simulations show that despite the simplicity of the physics forcings the models develop the tropical cyclone at horizontal grid spacings of about 55 km and finer. The simple-physics simulations reveal essential differences in the storm's structure and strength due to the choice of the dynamical core. Similar differences are also seen in complex full-physics aqua-planet experiments with CAM 5 which serve as a motivator for this work. The results suggest that differences in complex full-physics simulations can be, at least partly, replicated in simplified model setups. The simplified experiments might therefore provide easier access to an improved physical understanding of how the dynamical core and moist physical parameterizations interact. It is concluded that the simple-physics test case has the potential to close the gap between dry dynamical core assessments and full-physics aqua-planet experiments, and can shed light on the role of the dynamical core in the presence of moisture processes.

  5. Idealized tropical cyclone simulations of intermediate complexity: A test case for AGCMs

    NASA Astrophysics Data System (ADS)

    Reed, Kevin A.; Jablonowski, Christiane

    2012-02-01

    The paper introduces a moist, deterministic test case of intermediate complexity for Atmospheric General Circulation Models (AGCMs). We suggest pairing an AGCM dynamical core with simple physical parameterizations to test the evolution of a single, idealized, initially weak vortex into a tropical cyclone. The initial conditions are based on an initial vortex seed that is in gradient-wind and hydrostatic balance. The suggested "simple-physics" package consists of parameterizations of bulk aerodynamic surface fluxes for moisture, sensible heat and momentum, boundary layer diffusion, and large-scale condensation. Such a configuration includes the important driving mechanisms for tropical cyclones, and leads to a rapid intensification of the initial vortex over a forecast period of ten days. The simple-physics test paradigm is not limited to tropical cyclones, and can be universally applied to other flow fields. The physical parameterizations are described in detail to foster model intercomparisons. The characteristics of the intermediate-complexity test case are demonstrated with the help of four hydrostatic dynamical cores that are part of the Community Atmosphere Model version 5 (CAM 5) developed at the National Center for Atmospheric Research (NCAR). In particular, these are the Finite-Volume, Spectral Element, and spectral transform Eulerian and semi-Lagrangian dynamical cores that are coupled to the simple-physics suite. The simulations show that despite the simplicity of the physics forcings the models develop the tropical cyclone at horizontal grid spacings of about 55 km and finer. The simple-physics simulations reveal essential differences in the storm's structure and strength due to the choice of the dynamical core. Similar differences are also seen in complex full-physics aqua-planet experiments with CAM 5 which serve as a motivator for this work. The results suggest that differences in complex full-physics simulations can be, at least partly, replicated in simplified model setups. The simplified experiments might therefore provide easier access to an improved physical understanding of how the dynamical core and moist physical parameterizations interact. It is concluded that the simple-physics test case has the potential to close the gap between dry dynamical core assessments and full-physics aqua-planet experiments, and can shed light on the role of the dynamical core in the presence of moisture processes.

  6. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    NSDL National Science Digital Library

    COMET

    2004-11-10

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

  9. 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.

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

    NSDL National Science Digital Library

    Lori Perkins

    2003-01-09

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

  11. Idealized Tropical Cyclone Simulations of Intermediate Complexity: A Test Case for AGCMs

    NASA Astrophysics Data System (ADS)

    Reed, K. A.; Jablonowski, C.

    2011-12-01

    The testing of atmospheric general circulation models (AGCMs) is an important component of continued model evaluation and improvement. These tests help reveal the impact of an individual AGCM's design on the representation of atmospheric circulation and climate. The hierarchy of test cases for AGCMs spans deterministic and statistical dry dynamical core tests, aqua-planet experiments with complex physical parameterizations, climate-like simulations with prescribed sea surface temperatures (SSTs) and sea ice, and fully-coupled atmosphere-ocean simulations. The increase in complexity helps support the systematic evaluation of the AGCM designs and their dynamical cores. However, there is a large gap in complexity between dry dynamical core and full-physics aqua-planet runs that makes it difficult to understand the causes and effects of model differences and the dynamics-physics interaction. We introduce a test case of intermediate complexity. Therein we suggest that an AGCM dynamical core be paired with simple moist physics to test the evolution of a single, idealized, initially weak vortex into a tropical cyclone over 10 simulation days. The initial conditions are based on an initial vortex seed that is in gradient-wind and hydrostatic balance. The simple physics consists of parameterizations of bulk surface fluxes for moisture, sensible heat and momentum, vertical diffusion in the boundary layer, and large-scale condensation. This simple-physics configuration thereby includes important driving mechanisms for tropical cyclones, and leads to a rapid intensification of the initial vortex over a forecast period of 10 days. The presentation pays special attention to the impact of the AGCM dynamical core on the evolution of the tropical cyclone. The dynamical core is the central component of every AGCM and determines the numerical methods, diffusion properties and computational mesh for the resolved fluid flow. In particular, we investigate four dynamical cores that are part of NCAR's hydrostatic Community Atmosphere Model CAM 5. The research reveals the influence of the numerical schemes on the evolution of the cyclone and comparisons to simulations with the CAM 5 full-physics package is presented. It is shown that the simple-physics simulations capture the dominant characteristics of the tropical storm. The setup is therefore recommended as a moist AGCM test case of intermediate complexity.

  12. The Vertical Structure of Precipitation in Tropical Cyclones as seen by the TRMM PR

    NASA Astrophysics Data System (ADS)

    Hence, D. A.; Houze, R.

    2011-12-01

    Ten years of three-dimensional Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) echoes reveal the typical vertical structure of precipitation features seen in tropical cyclones. Statistical analyses based on annular regions spaced evenly from the center of the cyclone indicate different vertical precipitation structures for the eyewall, the organized rainbands closest to the storm center, and the disorganized rainbands further afield. When a concentric eyewall forms outside of an existing eyewall, the vertical structure of the outer eyewall is a hybrid of typical eyewall and inner rainband structure. The eyewall contains high reflectivities and high echo-tops, with deeper and more intense but highly intermittent echo perturbations superimposed on the basic structure. The inner rainband echoes are intense but less deep and highly uniform at all levels, mostly containing stratiform precipitation with a limited amount of vertically-constrained convection, In tropical cyclones with concentric eyewalls, the upper-troposphere portions of the outer eyewalls are weak and uniform like the inner rainbands, but the lower-tropospheric portions are more intense and uniform than rainbands of single eyewall storms. The distant rainbands are weaker, sparse, highly convective and less vertically constrained. The PR data are normalized by the amount of radar echo in each sample and examined quadrant-by-quadrant relative to the direction of the environmental shear. The changes in these normalized statistics indicate that the eyewall convection generates in the downshear-right quadrant, matures in the downshear-left, and dissipates in the upshear-left. In the rainbands, the convection initiates in the upshear-right quadrant of the distant rainbands, matures in the downshear right quadrant as it travels inwards, and dissipates in the downshear-left quadrant of the inner rainbands. The non-normalized statistics indicate that the associated rainfall asymmetry places most of the rainfall in the downshear-left quadrant of the eyewall and rainbands, both from precipitation particles travelling downwind along the eyewall and rainbands as well as particles travelling outward from the inner regions of the storm. These results indicate that environmental wind shear is mostly responsible for the changes in convective structure around tropical cyclone eyewalls and rainbands as well as the placement of rainfall around the storm. In storms with concentric eyewalls, the inner eyewall is more strongly affected by shear than are the eyewalls of single eyewall storms, while the outer eyewalls are relatively unaffected by shear, suggesting that the outer eyewall is amplifying the shear-induced asymmetry of the inner eyewall.

  13. 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

  14. 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).

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Srivastava, Kuldeep; Bhardwaj, Rashmi

    2014-08-01

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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  19. 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

  20. 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.

  1. Linkages of remote sea surface temperatures and Atlantic tropical cyclone activity mediated by the African monsoon

    NASA Astrophysics Data System (ADS)

    Taraphdar, Sourav; Leung, L. Ruby; Hagos, Samson

    2015-01-01

    sea surface temperatures (SSTs) in North Atlantic and Mediterranean (NAMED) can influence tropical cyclone (TC) activity in the tropical East Atlantic by modulating summer convection over western Africa. Analysis of 30 years of observations demonstrates that warm NAMED SST is linked to a strengthening of the Saharan heat low and enhancement of moisture and moist static energy in the lower troposphere over West Africa, which favors a northward displacement of the monsoonal front. These processes also lead to a northward shift of the African easterly jet that introduces an anomalous positive vorticity from western Africa to the main development region (50°W-20°E; 10°N-20°N) of Atlantic TCs. By modulating multiple African monsoon processes, NAMED SST explains comparable and approximately one third of the interannual variability of Atlantic TC frequency as that explained by local wind shear and local SST, respectively, which are known key factors that influence Atlantic TC development.

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

    NSDL National Science Digital Library

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The Vertical Structure of Precipitation in Tropical Cyclones as seen by the TRMM Precipitation Radar

    NASA Astrophysics Data System (ADS)

    Hence, Deanna A.

    2011-07-01

    Ten years of three-dimensional Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) echoes reveal the typical vertical structure of precipitation features seen in tropical cyclones. Statistical analyses based on annular regions spaced evenly from the center of the cyclone indicate different vertical precipitation structures for the eyewall, the organized rainbands closest to the storm center, and the disorganized rainbands further afield. When a concentric eyewall forms outside of an existing eyewall, the vertical structure of the outer eyewall is a hybrid of typical eyewall and inner rainband structure. The eyewall contains high reflectivities and high echo-tops, with deeper and more intense but highly intermittent echo perturbations superimposed on the basic structure. The inner rainband echoes are intense but less deep and highly uniform at all levels, mostly containing stratiform precipitation with a limited amount of vertically-constrained convection. In tropical cyclones with concentric eyewalls, the upper-troposphere portions of the outer eyewalls are weak and uniform like the inner rainbands, but the lower-tropospheric portions are more intense and uniform than rainbands of single eyewall storms. The distant rainbands are weaker, sparse, highly convective and less vertically constrained. The PR data are normalized by the maximum frequency of radar echo in each sample and examined radially and quadrant-by-quadrant relative to the direction of the environmental vertical wind shear. The changes in these normalized statistics indicate that the eyewall convection generates in the downshear-right quadrant, matures in the downshear-left, and dissipates in the upshear-left. In the rainbands, the convection initiates in the upshear-right quadrant of the distant rainbands, matures in the downshear right quadrant as it travels inwards, and dissipates in the downshear-left quadrant of the inner rainbands. These asymmetries increase with shear intensity. Variations in vertical wind shear also alter the distribution of upper-level ice particles. Variations in storm translation can modify this shear asymmetry somewhat, but shear dominates the asymmetric signal. Variations in storm intensity impact the intensity and location of eyewall, inner and distant rainband convection differently and also impact the distribution of low-level precipitation particles. Variations in sea surface temperature moderate the amount of buoyant convection evenly throughout the cyclone.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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."

  15. 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.

  16. 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.

  17. 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.

  18. Impacts of the two types of El Niño on Pacific tropical cyclone activity

    NASA Astrophysics Data System (ADS)

    Xu, Shibin; Huang, Fei

    2015-04-01

    It is well known that Tropical cyclone (TC) activities over the Pacific are affected by El Niño events. In most studies El Niño phenomena have been separated into east Pacific warming (EPW) and central Pacific warming (CPW) based on the location of maximum SST anomaly. Since these two kinds of El Niño have different impacts on Pacific tropical cyclone activities, this study investigates different features of TC activities and the genesis potential index (GPI) during EPW years and CPW years. Four contributing factors, i.e., the low-level absolute vorticity, the relative humidity, the potential intensity and the vertical wind shear, are examined to determine which factors are most important in causing the anomalous TC activities. Our results show that during EPW years in July-August (JA0), TC activities are more frequent with stronger intensity over the Western North Pacific (WNP) and Eastern North Pacific (ENP). The maximum anomaly center of TC activities then drifts eastward significantly in September-October (SO0). However, centers of anomalous TC activity barely change from JA0 to SO0 during CPW years. In January-February-March (JFM1) of the decaying years of warming events, TC frequency and intensity both have positive anomaly over the South Pacific. The anomalies in EPW years have larger amplitude and wider spatial distribution than those in CPW years. These anomalous activities of TC are associated with GPI anomaly and the key factors affecting GPI anomaly for each ocean basin are quite different.

  19. Quadrant distribution of tropical cyclone inner-core kinematics in relation to environmental shear

    NASA Astrophysics Data System (ADS)

    DeHart, Jennifer C.

    Airborne Doppler radar data collected in tropical cyclones by National Oceanic and Atmospheric Administration WP-3D aircraft over an eight-year period (2003-2010) is used to statistically analyze the vertical structure of tropical cyclone eyewalls with reference to the deep layer shear. Convective evolution within the inner core conforms to patterns shown by previous studies: convection initiates downshear-right, intensifies downshear-left and weakens upshear. Analysis of the vertical distribution of radar reflectivity and vertical air motion indicates the development of upper-level downdrafts in conjunction with strong convection downshear-left and a maximum in frequency upshear-left. Intense updrafts and downdrafts both conform to the shear asymmetry pattern. While strong updrafts occur within the eyewall, intense downdrafts show far more radial variability, particularly in the upshear-left quadrant, though they concentrate along the eyewall edges. Strong updrafts are collocated with low-level inflow and upper-level outflow superimposed on the background flow. In contrast, strong downdrafts occur in association with low-level outflow and upper-level inflow.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  2. Targeted observations to improve tropical cyclone track forecasts in the Atlantic and eastern Pacific basins

    NASA Astrophysics Data System (ADS)

    Aberson, Sim David

    In 1997, the National Hurricane Center and the Hurricane Research Division began conducting operational synoptic surveillance missions with the Gulfstream IV-SP jet aircraft to improve operational forecast models. During the first two years, twenty-four missions were conducted around tropical cyclones threatening the continental United States, Puerto Rico, and the Virgin Islands. Global Positioning System dropwindsondes were released from the aircraft at 150--200 km intervals along the flight track in the tropical cyclone environment to obtain wind, temperature, and humidity profiles from flight level (around 150 hPa) to the surface. The observations were processed and formatted aboard the aircraft and transmitted to the National Centers for Environmental Prediction (NCEP). There, they were ingested into the Global Data Assimilation System that subsequently provides initial and time-dependent boundary conditions for numerical models that forecast tropical cyclone track and intensity. Three dynamical models were employed in testing the targeting and sampling strategies. With the assimilation into the numerical guidance of all the observations gathered during the surveillance missions, only the 12-h Geophysical Fluid Dynamics Laboratory Hurricane Model forecast showed statistically significant improvement. Neither the forecasts from the Aviation run of the Global Spectral Model nor the shallow-water VICBAR model were improved with the assimilation of the dropwindsonde data. This mediocre result is found to be due mainly to the difficulty in operationally quantifying the storm-motion vector used to create accurate synthetic data to represent the tropical cyclone vortex in the models. A secondary limit on forecast improvements from the surveillance missions is the limited amount of data provided by the one surveillance aircraft in regular missions. The inability of some surveillance missions to surround the tropical cyclone with dropwindsonde observations is a possible third limit, though the results are inconclusive. Due to limited aircraft resources, optimal observing strategies for these missions must be developed. Since observations in areas of decaying error modes are unlikely to have large impact on subsequent forecasts, such strategies should be based on taking observations in those geographic locations corresponding to the most rapidly growing error modes in the numerical models and on known deficiencies in current data assimilation systems. Here, the most rapidly growing modes are represented by areas of large forecast spread in the NCEP bred-mode global ensemble forecasting system. The sampling strategy requires sampling the entire target region at approximately the same resolution as the North American rawinsonde network to limit the possibly spurious spread of information from dropwindsonde observations into data-sparse regions where errors are likely to grow. When only the subset of data in these fully-sampled target regions is assimilated into the numerical models, statistically significant reduction of the track forecast errors of up to 25% within the critical first two days of the forecast are seen. These model improvements are comparable with the cumulative business-as-usual track forecast model improvements expected over eighteen years.

  3. Remote effects of tropical cyclone wind forcing over the western Pacific on the eastern equatorial ocean

    NASA Astrophysics Data System (ADS)

    Zhang, Rong-Hua; Pei, Yuhua; Chen, Dake

    2013-11-01

    An ocean general circulation model (OGCM) is used to demonstrate remote effects of tropical cyclone wind (TCW) forcing in the tropical Pacific. The signature of TCW forcing is explicitly extracted using a locally weighted quadratic least-squares regression (called as LOESS) method from six-hour satellite surface wind data; the extracted TCW component can then be additionally taken into account or not in ocean modeling, allowing isolation of its effects on the ocean in a clean and clear way. In this paper, seasonally varying TCW fields in year 2008 are extracted from satellite data which are prescribed as a repeated annual cycle over the western Pacific regions off the equator (poleward of 10°N/S); two long-term OGCM experiments are performed and compared, one with the TCW forcing part included additionally and the other not. Large, persistent thermal perturbations (cooling in the mixed layer (ML) and warming in the thermocline) are induced locally in the western tropical Pacific, which are seen to spread with the mean ocean circulation pathways around the tropical basin. In particular, a remote ocean response emerges in the eastern equatorial Pacific to the prescribed off-equatorial TCW forcing, characterized by a cooling in the mixed layer and a warming in the thermocline. Heat budget analyses indicate that the vertical mixing is a dominant process responsible for the SST cooling in the eastern equatorial Pacific. Further studies are clearly needed to demonstrate the significance of these results in a coupled ocean-atmosphere modeling context.

  4. 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.

  5. 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.

  6. Assessment of landscape change associated with tropical cyclone phenomena in Baja California Sur, Mexico, using satellite remote sensing

    Microsoft Academic Search

    Genaro Martinez-Gutierrez

    2002-01-01

    Baja California Sur (Mexico), as well as mainland Mexico, is affected by tropical cyclone storms, which originate in the eastern north Pacific. Historical records show that Baja has been damaged by intense summer storms. An arid to semiarid climate characterizes the study area, where precipitation mainly occurs during the summer and winter seasons. Natural and anthropogenic changes have impacted the

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

    E-print Network

    Wang, Yuqing

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

  8. Impact of Secondary Eyewall Heating on Tropical Cyclone Intensity Change* XIAQIONG ZHOU, BIN WANG, XUYANG GE, AND TIM LI

    E-print Network

    Wang, Bin

    mini- mum region, known as a moat, in intense tropical cyclones (TCs) (Fortner 1956; Willoughby et al. 1982; Black and Willoughby 1992; Hawkins et al. 2006). As the outer eyewall forms, the inner one the end of a deepening phase (Fortner 1956; Willoughby et al. 1982). Kuo et al. (2009) examined

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

    E-print Network

    Hodges, Kevin

    A Comparison of Extra-tropical Cyclones in Recent Re-analyses; ERA-INTERIM, NASA-MERRA, NCEP-CFSR-Interim is lower than in the NH, but for NASA-MERRA and NCEP-CFSR the number matched is similar to the NH. The mean

  10. A new paradigm for intensity modification of tropical cyclones: thermodynamic impact of vertical wind shear on the inflow layer

    Microsoft Academic Search

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

    2010-01-01

    An important roadblock to improved intensity forecasts for tropical cyclones (TCs) is our incomplete understanding of the interaction of a TC with the environmental flow. In this paper we re-visit the canonical problem of a TC in vertical wind shear on an f-plane. A suite of numerical experiments is performed with intense TCs in moderate to strong vertical shear. We

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

    Microsoft Academic Search

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

    2010-01-01

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

  12. Interaction of an Asymmetric Double Vortex and Trochoidal Motion of a Tropical Cyclone with the Concentric Eyewall Structure

    Microsoft Academic Search

    Masahito Oda; Mikio Nakanishi; Gen'Ichi Naito

    2006-01-01

    Radar echo images demonstrate that mature tropical cyclones frequently have a concentric eyewall structure, which consists of the inner eyewall, echo-free moat, and outer eyewall regions. Near the inner and outer eyewalls, well-defined wind maxima are generally observed. This indicates that two large vertical vorticity regions exist just inside radii of the two wind maxima near the inner and outer

  13. The Influence of Rainfall on Scatterometer Backscatter Within Tropical Cyclone Environments—Implications on Parameterization of Sea-Surface Stress

    Microsoft Academic Search

    David E. Weissman; Mark A. Bourassa

    2011-01-01

    The use of satellite scatterometers to probe the winds in and near strong tropical cyclones (TCs) is a valuable tool for both numerical weather prediction and weather forecasters. The presence of widespread rain in these storms impedes the estima- tion of surface winds from the radar cross section measurements, when using a Ku-band radar. This paper seeks improvements in the

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    SciTech Connect

    Lackmann, Gary

    2013-06-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  1. 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.

  2. 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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  4. 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.

  5. 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.

  6. 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.

  7. Clustering analysis of western North Pacific Tropical Cyclone tracks using the Self Organizing Map

    NASA Astrophysics Data System (ADS)

    Kim, H.; Seo, K.

    2013-12-01

    A cluster analysis using Self Organizing Map (SOM) is used to characterize tropical cyclone (TC) tracks over the western North Pacific. A False Discovery Rate (FDR) method is used to objectively determine an optimum cluster number. For 620 TC tracks over the WNP from June-October during 1979-2010, the five clusters for TC tracks are selected. These can further be categorized into three major patterns: straight-moving track, recurving track, and quasi-random pattern. Each pattern is characterized by land falling regions: near South and East China, East Asia, and off-shore of Japan. In addition, each pattern shows distinctive properties in its traveling distance, lifetime, intensity (mean minimum sea level pressure), and genesis location. It is revealed that these three patterns are associated with the large-scale dynamics such as variability of the western Pacific subtropical high and the Madden-Julian Oscillation. The impacts of El Nino and NAO will be discussed.

  8. Applications of custom developed object based analysis tool: Precipitation in Pacific, Tropical cyclones precipitation, Hail areas

    NASA Astrophysics Data System (ADS)

    Skok, Gregor; Rakovec, Jože; Strajnar, Benedikt; Bacmeister, Julio; Tribbia, Joe

    2014-05-01

    In the last few years an object-based analysis software tool was developed at University of Ljubljana in collaboration with National Center for Atmospheric Research (NCAR). The tool was originally based on ideas of the Method for Object-Based Diagnostic Evaluation (MODE) developed by NCAR but has since evolved and changed considerably and is now available as a separate free software package. The software is called the Forward in Time object analysis tool (FiT tool). The software was used to analyze numerous datasets - mainly focusing on precipitation. Climatology of satellite and model precipitation in the low-and-mid latitude Pacific Ocean was performed by identifying and tracking of individual perception systems and estimating their lifespan, movement and size. A global climatology of tropical cyclone precipitation was performed using satellite data and tracking and analysis of areas with hail in Slovenia was performed using radar data. The tool will be presented along with some results of applications.

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

    NASA Astrophysics Data System (ADS)

    Phibbs, Samuel; Toumi, Ralf

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  11. Tropical cyclone kinetic energy and structure evolution in the HWRFx model

    NASA Astrophysics Data System (ADS)

    Maclay, Katherine S.

    2011-07-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  14. Numerical simulation of changes in tropical cyclone intensity using a coupled air-sea model

    NASA Astrophysics Data System (ADS)

    Duan, Yihong; Wu, Rongsheng; Yu, Runling; Liang, Xudong

    2013-10-01

    A coupled air-sea model for tropical cyclones (TCs) is constructed by coupling the Pennsylvania State University/National Center for Atmospheric Research mesoscale model (MM5) with the Princeton Ocean Model. Four numerical simulations of tropical cyclone development have been conducted using different configurations of the coupled model on the f-plane. When coupled processes are excluded, a weak initial vortex spins up into a mature symmetric TC that strongly resembles those observed and simulated in prior research. The coupled model reproduces the reduction in sea temperature induced by the TC reasonably well, as well as changes in the minimum central pressure of the TC that result from negative atmosphere-ocean feedbacks. Asymmetric structures are successfully simulated under conditions of uniform environmental flow. The coupled ocean-atmosphere model is suitable for simulating air-sea interactions under TC conditions. The effects of the ocean on the track of the TC and changes in its intensity under uniform environmental flow are also investigated. TC intensity responds nonlinearly to sea surface temperature (SST). The TC intensification rate becomes smaller once the SST exceeds a certain threshold. Oceanic stratification also influences TC intensity, with stronger stratification responsible for a larger decrease in intensity. The value of oceanic enthalpy is small when the ocean is weakly stratified and large when the ocean is strongly stratified, demonstrating that the oceanic influence on TC intensity results not only from SST distributions but also from stratification. Air-sea interaction has only a slight influence on TC movement in this model.

  15. 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.

  16. 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

  17. Environmental Modeling, Technology, and Communication for Land Falling Tropical Cyclone/Hurricane Prediction

    PubMed Central

    Tuluri, Francis; Reddy, R. Suseela; Anjaneyulu, Y.; Colonias, John; Tchounwou, Paul

    2010-01-01

    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 (Wmax) 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

  18. Potential impact of the colored Amazon and Orinoco plume on tropical cyclone intensity

    NASA Astrophysics Data System (ADS)

    Newinger, C.; Toumi, R.

    2015-02-01

    The Amazon and the Orinoco river plumes modulate ocean stratification and color in the tropical North Atlantic. This changes air-sea interactions and may thus be important for tropical cyclones (TCs). Using a regional ocean model, we try to separate the potential impact of river freshwater and light absorption on ocean temperatures, stability, and TC intensity. While the freshwater plume stabilizes the water column, there is no significant change in sea surface temperatures. However, increased stability and temperature inversions may reduce surface cooling feedbacks. The cooling inhibition index (CI) is +2.2 (J/m2)1/3 larger when the river freshwater plume is present. Ocean color in the river plume on the other hand, blocks the deeper ocean from sunlight, leading to moderate surface warming (+0.1°C) and substantial subsurface cooling (-0.3°C 100 m mean temperature). As a consequence cold water is more readily available to passing storms and the CI decreases by -2.1 (J/m2)1/3. Using simple, idealized relationships between expected surface cooling and TC intensity, we find that river-induced stability enhances strong TCs by up to -5 to -12 hPa, while ocean color may reduce intensity by +8 hPa to +16 hPa. The net impact of the colored plume is negligible for weak storms and a slight intensity reduction for stronger cyclones. Within the Amazon and Orinoco plume, the river freshwater effect may thus be substantially reduced or even offset by light absorbing particles.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  1. Imprints of Catastrophic Cyclones in Trace Element Records (Mg, Na, S, P) of Tropical Stalagmites

    NASA Astrophysics Data System (ADS)

    Murgulet, V.; Aharon, P.

    2006-12-01

    Whereas trace element variations in speleothems have been widely used to solve problems concerning groundwater residence times, growth rates, rainfall and air temperature histories, their application as proxies of severe storm events has only recently been considered. Here we test whether trace element proxies in stalagmites from Niue, (19° 00'S; 169° 50'W), one of the largest carbonate island in the South Pacific, record passing severe cyclones. Niue Island offers an unparalleled opportunity to carry on the test because (i) it lies within the belt of the South Pacific cyclones that strike the island periodically (ii) it supports flank-margin caves that are strung on the leeward site along a narrow terraced strip rising to a height of 20 to 23 m above sea level and terminating at the coast in steep sea cliffs, and (iii) the caves contain actively growing speleothems overlapping in time with the instrumentally recorded cyclones that hit the island. Niue Island is in the path of the SE trade winds that carry sea spray to the windward site while the leeward site is sheltered. In contrast, the leeward island is battered by rainfall deluges mixed with sea spray and storm surges only during severe cyclone events. Two actively growing stalagmites whose chronology has been previously established (Rabsury, M. and P. Aharon, G3, 2006) have been investigated using high-resolution trace element profiling and X-ray mapping by electron microprobe. The stalagmites, sampled in 2002, contain almost two century-long records and consist of sub-annual couplets alternating between thick, light calcite bands deposited during the austral monsoon summer and thin, dark calcite layers deposited during the austral dry winter. Comparison of the optical couplets with elemental X-ray maps reveals that the thin dark layers are higher in Mg relative to the light thick layers, and typically Mg correlates inversely with P and S. The sub-annual cycles are disrupted by approximately seven abrupt increases in Mg, S, Na and P concentrations throughout the stalagmites. The youngest abrupt change occurred around 1989-1990 AD when two consecutive severe cyclones (Fili in 1989 and Ofa in1990) hit directly the northwest leeward coast and caused considerable damage in life and property. The observed trace element increases (Mg~1.4 wt%, S~0.3 wt%, Na~0.25 wt%, and P~0.08 wt%) are accompanied by changes in stalagmite color and layering disruptions. We will report the fit between older abrupt chemical changes and known cyclone events, and discuss the processes controlling trace element concentrations in these stalagmites. References Rasbury, M., and P. Aharon (2006), ENSO-controlled rainfall variability records archived in tropical stalagmites from the mid-ocean island of Niue, South Pacific, Geochem. Geophys. Geosyst., 7, Q07010, doi:10.1029/2005GC001232.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  4. Simulation of Tropical Cyclone Circulation Over the Bay of Bengal Using the Arakawa-Schubert Cumulus Parameterization. Part II: Some Sensitivity Experiments

    Microsoft Academic Search

    D. V. Bhaskar Rao; K. Ashok

    2001-01-01

    - The role of sea-surface temperature (SST) and Coriolis parameter in the evolution and intensification of tropical cyclones has been examined using the ten-level axi-symmetric primitive equation model described in the companion paper (Bhaskar Rao and Ashok, 1999). Two experiments have been conducted using the ten-level model to assess the role of Coriolis parameter ``f'' in tropical cyclone intensity and

  5. 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.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  10. Idealized numerical simulations of tropical cyclone formation associated with monsoon gyres

    NASA Astrophysics Data System (ADS)

    Liang, Jia; Wu, Liguang; Zong, Huijun

    2014-03-01

    Monsoon gyres have been identified as one of the important large-scale circulation patterns associated with tropical cyclone (TC) formation in the western North Pacific. A recent observational analysis indicated that most TCs form near the center of monsoon gyres or at the northeast end of the enhanced low-level southwesterly flows on the southeast-east periphery of monsoon gyres. In the present reported study, idealized numerical experiments were conducted to examine the tropical cyclogenesis associated with Rossby wave energy dispersion with an initial idealized monsoon gyre. The numerical simulations showed that the development of the low-level enhanced southwesterly flows on the southeast-east periphery of monsoon gyres can be induced by Rossby wave energy dispersion. Mesoscale convective systems emerged from the northeast end of the enhanced southwesterly flows with mid-level maximum relative vorticity. The simulated TC formed in the northeast of the monsoon gyre and moved westward towards the center of the monsoon gyre. The numerical experiment with a relatively smaller sized initial monsoon gyre showed the TC forming near the center of the initial monsoon gyre. The results of the present study suggest that Rossby wave energy dispersion can play an important role in TC formation in the presence of monsoon gyres.

  11. Necessary Conditions for Tropical Cyclone Rapid Intensification as Derived from 11 Years of TRMM Data

    NASA Astrophysics Data System (ADS)

    Jiang, H.; Ramirez, E. M.

    2012-12-01

    Understanding and predicting intensity changes, especially rapid intensification (RI), of tropical cyclones (TCs) require some understanding of not only the large-scale environment condition, but also the convective and precipitation properties of the storm. Convective and rainfall properties of TCs are statistically quantified for different TC intensity change categories by using Tropical Rainfall Measuring Mission (TRMM) data from December 1997 to December 2008. Four 24-h future intensity change categories are defined: rapidly intensifying (RI), slowly intensifying, neutral, and weakening. Maximum convective intensity in the inner core is not necessarily more intense prior to undergoing an RI episode than a slowly intensifying, neutral, or weakening episode. Instead, a minimum threshold of convective intensity, raining area, and total volumetric rain in the inner core has to be reached before a storm undergoes RI. The following necessary conditions for RI are found in the inner core: maximum near surface radar reflectivity > 40 dBZ, maximum 20 (30, 40) dBZ echo height > 8 (6, 4) km, minimum 85 (37) GHz polarization corrected brightness temperature (PCT) < 235 (275) K, minimum 10.8 ?m brightness temperature < 220 K, total raining area > 3,000 km^2, and total volumetric rain > 5,000 mm h-1 km^2. It is also found that total lightning activities in the inner core (outer rainband) have a negative (positive) relationship with storm intensification.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  15. 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.

  16. Sensitivities of AGCM-Simulated Tropical Cyclones to Varying Initial Conditions

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  17. 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.

  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. The importance of low-deformation vorticity in tropical cyclone formation

    NASA Astrophysics Data System (ADS)

    Tory, K. J.; Dare, R. A.; Davidson, N. E.; McBride, J. L.; Chand, S. S.

    2012-07-01

    Studies of tropical cyclone (TC) formation from tropical waves have shown that TC formation requires a wave-relative quasi-closed circulation: the "marsupial pouch" concept. This results in a layerwise nearly contained region of atmosphere in which the modification of moisture, temperature and vorticity profiles by convective and boundary layer processes occurs undisturbed. The pouch concept is further developed in this paper. TCs develop near the centre of the pouch where the flow is in near solid body rotation. A reference-frame independent parameter is introduced that effectively measures the level of solid-body rotation in the lower troposphere. The parameter is the product of a normalized Okubo-Weiss parameter and absolute vorticity (OWZ). Using 20 yr of ERA-interim reanalysis data and the IBTrACS global TC database, it is shown 95% of TCs including, but not limited to, those forming in tropical waves are associated with enhanced levels of OWZ on both the 850 and 500 hPa pressure levels at the time of TC declaration, while 90% show enhanced OWZ for at least 24 h prior to declaration. This result prompts the question of whether the pouch concept extends beyond wave-type formation to all TC formations world-wide. Combining the OWZ with a low vertical shear requirement and lower troposphere relative humidity thresholds, an imminent genesis parameter is defined. The parameter includes only relatively large-scale fluid properties that are resolved by coarse grid model data (>150 km), which means it can be used as a TC detector for climate model applications. It is also useful as a cyclogenesis diagnostic in higher resolution models such as real-time global forecast models.

  20. The importance of low-deformation vorticity in tropical cyclone formation

    NASA Astrophysics Data System (ADS)

    Tory, K. J.; Dare, R. A.; Davidson, N. E.; McBride, J. L.; Chand, S. S.

    2013-02-01

    Studies of tropical cyclone (TC) formation from tropical waves have shown that TC formation requires a wave-relative quasi-closed circulation: the "marsupial pouch" concept. This results in a layerwise nearly contained region of atmosphere in which the modification of moisture, temperature and vorticity profiles by convective and boundary layer processes occurs undisturbed. The pouch concept is further developed in this paper. TCs develop near the centre of the pouch where the flow is in near solid body rotation. A reference-frame independent parameter is introduced that effectively measures the level of solid-body rotation in the lower troposphere. The parameter is the product of a normalized Okubo-Weiss parameter and absolute vorticity (OWZ). Using 20 yr of ERA-interim reanalysis data and the IBTrACS global TC database, it is shown 95% of TCs including, but not limited to, those forming in tropical waves are associated with enhanced levels of OWZ on both the 850 and 500 hPa pressure levels at the time of TC declaration, while 90% show enhanced OWZ for at least 24 h prior to declaration. This result prompts the question of whether the pouch concept extends beyond wave-type formation to all TC formations world-wide. Combining the OWZ with a low vertical shear requirement and lower troposphere relative humidity thresholds, an imminent genesis parameter is defined. The parameter includes only relatively large-scale fluid properties that are resolved by coarse grid model data (>150 km), which means it can be used as a TC detector for climate model applications. It is also useful as a cyclogenesis diagnostic in higher resolution models such as real-time global forecast models.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  4. 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.

  5. Analysis of tropical cyclone intensification trends and variability in the North Atlantic Basin over the period 1970–2003

    Microsoft Academic Search

    R. C. Balling Jr; R. S. Cerveny

    2006-01-01

    Summary  Over the past three decades, the sea-surface temperatures of the lower latitudes of the North Atlantic basin have increased\\u000a while the lower-tropospheric temperatures show no upward trend. This differential warming of the atmosphere may have a destabilizing\\u000a effect that could influence the development and intensification of tropical cyclones (TCs). In this investigation, we find\\u000a that in general, TC intensification (a)

  6. Contributions of Atlantic tropical cyclones to monthly and seasonal rainfall in the eastern United States 1960–2007

    Microsoft Academic Search

    Ricardo C. Nogueira; Barry D. Keim

    2011-01-01

    Tropical cyclone activity in the North Atlantic Basin experiences great variability on intra-annual, interannual, and interdecadal\\u000a timescales. George Cry found that TC rainfall presents an intra-seasonal pattern over the eastern USA, contributing up to\\u000a 40% of total monthly rainfall. This study replicates much of what was done by Cry using a denser rain gauge network and more\\u000a sophisticated techniques for

  7. Multi-model Projection of Global Warming Impact on Tropical Cyclone Genesis Frequency over the Western North Pacific

    Microsoft Academic Search

    Satoru YOKOI; Yukari N. TAKAYABU

    2009-01-01

    This study examines the global warming impact on tropical cyclone (TC) genesis frequency over the western North Pacific basin (0°-40°N, 100°E-180°; WNP) projected by five atmosphere-ocean coupled general circulation models that participate in the World Climate Research Programme's Coupled Model Intercomparison Project phase 3 (CMIP3), and exhibit high performances in simulating horizontal distribution of annual-mean frequency under the current climate

  8. Multi-model comparison of global warming impacts on tropical cyclone genesis frequency over the western North Pacific

    Microsoft Academic Search

    S. Yokoi; Y. N. Takayabu

    2008-01-01

    This study examines global warming impact on tropical cyclone (TC) genesis frequency over the western North Pacific basin (Eq.-40°N, 100°E-180°) predicted by 5 coupled general circulation models that participate in the third phase of Climate Model Intercomparison Project (CMIP3), which exhibit high performance in simulating horizontal distribution of the genesis frequency under the current climate condition. TC-like disturbances are detected

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Meteorological impacts of sea-surface temperature associated with the humid airflow from Tropical Cyclone Talas (2011)

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.

    2014-07-01

    This paper examines meteorological impacts of sea-surface temperature (SST) in the presence of the humid airflow from Tropical Cyclone Talas (2011). To investigate the influence of the SST on the severe weather in and around Japan, sensitivity simulations were conducted using six SST data products covering a period of 7 days. The upward sea-surface latent heat flux that accumulated over the 7-day period was high around the Kuroshio during the slow passage of the tropical cyclone. Large differences were found among the individual SST products around the southern coast of Japan. The coastal warm SST anomaly of ~ 1.5 °C enhanced the surface upward latent heat fluxes (by 60 to 80%), surface southeasterly winds (by 6 to 8%), and surface water mixing ratios (by 4%) over the coastal sea area. The enhanced latent heat flux resulting from the coastal SST anomaly contributed to the further enhancement of the latent heat flux itself via a positive feedback with the amplified surface horizontal wind. The SST anomalies produced an anomaly in 7-day precipitation (ca. 40 mm) along the mountainsides and over a coastal area where the surface wind anomaly was locally large. Thus, coastal SST error is important in the atmospheric simulation of accumulated evaporation and precipitation associated with tropical cyclones making landfall.

  11. 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.

  12. 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.

  13. Tropical cyclone rainfall: An observational and numerical study of the structure and governing physical processes

    NASA Astrophysics Data System (ADS)

    Lonfat, Manuel

    Fresh water flooding has become the largest threat to life at hurricane landfall in the United States, in part because of a lack of skill of current Quantitative Precipitation Forcast (QPF) methods. This study aims to develop a global climatology of tropical cyclone (TC) rainfall and to improve our understanding of physical processes that affect the TC rainfall structure and distribution, using satellite observations and numerical simulations. First, the TC rainfall distributions with respect to the storm intensity and location are examined, using global satellite observations from the Tropical Rainfall Measuring Mission (TRMM). Secondly, numerical simulations using the Penn State/National Centers for Atmospheric Research (NCAR) mesoscale modelling system, version 5 (MM5), are performed to study how specific processes affect the cyclone rainfall. The presence of moisture and momentum sources on a storm's inner core is investigated using a method that modifies the environmental conditions in the model. The mean TC rainfall distribution and the first order asymmetry vary with storm intensity and geographical location among the six oceanic basins. The mean rainfall increases with storm intensity within 250 km of the storm center while the radius of maximum rainfall decreases. The asymmetric component is determined by the first-order Fourier decomposition in a coordinate system relative to storm motion and shear. The rainfall asymmetry with TC motion varies significantly with both storm intensity and geographic location. For the global average of all TCs, the maximum rainfall is located in the front quadrants. However, the global composite asymmetry is larger when analysed with respect to shear. The asymmetry is observed down-shear left (right) in the Northern (Southern) Hemisphere for shear values >7.5 m s -1. The analysis is further extended to examine the net effect of the storm motion and the vertical wind shear. It is found that the storm-motion induced rainfall asymmetry is comparable to that induced by the shear when the shear is <5 m s-1. TC propagation speed becomes more important in the relatively low shear environment. The overall rainfall asymmetry, in all oceanic basins, depends on the angle and relative magnitude between the storm motion and shear vectors. The combined effect of shear and TC propagation speed is further investigated using numerical simulations of Hurricane Floyd (1999). Floyd was a well-observed intense storm that experienced variable environmental shear, from relatively low shear to close to 15 m s-1 high shear during its life cycle. (Abstract shortened by UMI.)

  14. 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

  15. 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.

  16. Climate extremes in the Pacific: improving seasonal prediction of tropical cyclones and extreme ocean temperatures to improve resilience

    NASA Astrophysics Data System (ADS)

    Kuleshov, Y.; Jones, D.; Spillman, C. M.

    2012-04-01

    Climate change and climate extremes have a major impact on Australia and Pacific Island countries. Of particular concern are tropical cyclones and extreme ocean temperatures, the first being the most destructive events for terrestrial systems, while the latter has the potential to devastate ocean ecosystems through coral bleaching. As a practical response to climate change, under the Pacific-Australia Climate Change Science and Adaptation Planning program (PACCSAP), we are developing enhanced web-based information tools for providing seasonal forecasts for climatic extremes in the Western Pacific. Tropical cyclones are the most destructive weather systems that impact on coastal areas. Interannual variability in the intensity and distribution of tropical cyclones is large, and presently greater than any trends that are ascribable to climate change. In the warming environment, predicting tropical cyclone occurrence based on historical relationships, with predictors such as sea surface temperatures (SSTs) now frequently lying outside of the range of past variability meaning that it is not possible to find historical analogues for the seasonal conditions often faced by Pacific countries. Elevated SSTs are the primary trigger for mass coral bleaching events, which can lead to widespread damage and mortality on reef systems. Degraded coral reefs present many problems, including long-term loss of tourism and potential loss or degradation of fisheries. The monitoring and prediction of thermal stress events enables the support of a range of adaptive and management activities that could improve reef resilience to extreme conditions. Using the climate model POAMA (Predictive Ocean-Atmosphere Model for Australia), we aim to improve accuracy of seasonal forecasts of tropical cyclone activity and extreme SSTs for the regions of Western Pacific. Improved knowledge of extreme climatic events, with the assistance of tailored forecast tools, will help enhance the resilience and adaptive capacity of Australia and Pacific Island Countries under climate change. Acknowledgement The research discussed in this paper was conducted with the support of the PACCSAP supported by the AusAID and Department of Climate Change and Energy Efficiency and delivered by the Bureau of Meteorology and CSIRO.

  17. Analysis of Tropical Cyclone Eye Slope Using Airborne Radar Reflectivity Data

    NASA Astrophysics Data System (ADS)

    Hazelton, A. T.; Hart, R. E.

    2011-12-01

    Understanding and forecasting tropical cyclone intensity change continues to be one of the biggest challenges in atmospheric research and forecasting. While the large-scale processes that govern TC intensity change (such as wind shear and ocean temperature) are relatively well-understood, the same cannot be said for smaller-scale inner-core processes and structure. For example, while the eyewall of a hurricane is known from observations to tilt outward with increasing height, there is no theory or even robust observational study to explain the magnitude of this tilt or what changes in that tilt signify. The relative lack of observations in the inner-core region has made research difficult for many decades. However, the recent increase in research flights (e.g. GRIP, PREDICT) into the cores of tropical storms has provided data that allows us to better analyze the complex factors that drive changes in the inner-structure of storms. This study makes use of airborne radar reflectivity data from different field experiments and a group of reconnaissance flights into hurricanes to study the vertical structure of the TC inner-core; specifically the slope of the eye. We analyze the relationship between the eye slope and the current storm intensity, and compare our results with the limited previous work on this topic (e.g. Stern and Nolan 2009, Shea and Gray 1973). We also investigate the relationship between the eye slope and the short-term intensity change, with hopes of better understanding the physical processes that result from changes in the eye structure. It is also hoped that this relationship with short-term intensity change may prove valuable in forecasting intensity.

  18. A relocation-based initialization scheme to improve track-forecasting of tropical cyclones

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Childs, Peter P.; Huang, Xiang-Yu; Jacobs, Neil A.; Min, Jinzhong

    2014-01-01

    A relocation procedure to initialize tropical cyclones was developed to improve the representation of the initial conditions and the track forecast for Panasonic Weather Solutions Tropical Operational Forecasts. This scheme separates the vortex perturbation and environment field from the first guess, then relocates the initial vortex perturbations to the observed position by merging them with the environment field. The relationships of wind vector components with stream function and velocity potential are used for separating the vortex disturbance from first guess. For the separation of scalars, a low-pass Barnes filter is employed. The irregular-shaped relocation area corresponding to the specific initial conditions is determined by mapping the edge of the vortex radius in 36 directions. Then, the non-vortex perturbations in the relocation area are removed by a two-pass Barnes filter to retain the vortex perturbations, while the variable fields outside the perimeter of the modified vortex are kept identical to the original first guess. The potential impacts of this scheme on track forecasts were examined for three hurricane cases in the 2011-12 hurricane season. The experimental results demonstrate that the initialization scheme is able to effectively separate the vortex field from the environment field and maintain a relatively balanced and accurate relocated first guess. As the initial track error is reduced, the following track forecasts are considerably improved. The 72-h average track forecast error was reduced by 32.6% for the cold-start cases, and by 38.4% when using the full-cycling data assimilation because of the accumulated improvements from the initialization scheme.

  19. 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.

  20. The relation between dry vortex merger and tropical cyclone genesis over the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Chen, Shu-Hua; Liu, Yi-Chin

    2014-10-01

    Using 33 year European Centre for Medium-Range Weather Forecasts Re-Analysis Interim reanalysis in the months of August and September, we found that more than half of the low-level, moist vortices (called wet vortices) originating from south of the African easterly jet merged with a shallow, dry vortex from the north after leaving the West African coast. A dry vortex involved with the merger process is referred to as a D-vortex, and the process is referred to as a D-vortex merger. Dry vortices influenced by more intense African easterly waves moved southwestward and had a greater potential to serve as D-vortices in the merger process. The D-vortex merger occurred in the predepression stage of 70% of tropical cyclones (TCs) that formed in the Atlantic main development region and in 55% of nondeveloping systems. Further analysis showed that developing systems with the D-vortex merger (DM) were statistically dominated by a more intense wet vortex whose 500 hPa relative humidity was also significantly higher, while nondeveloping systems with the D-vortex merger (NM) were dominated by a more intense dry vortex. The average intensity of wet vortices for DM was more intense than that for NM, significant at a 95% confidence level. Moreover, warmer Saharan air was observed for DM than NM. While TC genesis is largely controlled by the large-scale environment over ocean, differences in vortex characteristics and environment over northwestern Africa between DM and NM could potentially help predict whether a tropical system associated with the D-vortex merger will ultimately evolve into an Atlantic TC.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  2. The importance of extratropical and tropical cyclones on the short-term evolution of barrier islands along the northern Gulf of Mexico, USA

    Microsoft Academic Search

    Gregory W. Stone; Baozhu Liu; David A. Pepper; Ping Wang

    2004-01-01

    Data are presented indicating the complexity and highly variable response of beaches to cold front passages along the northern Gulf of Mexico, in addition to the impacts of tropical cyclones and winter storms. Within the past decade, an increase in the frequency of tropical storms and hurricanes impacting the northern Gulf has dramatically altered the long-term equilibrium of a large

  3. WINTER STORM AND TROPICAL CYCLONE IMPACTS ON THE SHORT TERM EVOLUTION OF BEACHES AND BARRIERS ALONG THE NORTH EASTERN GULF OF MEXICO

    Microsoft Academic Search

    Gregory W. Stone; Baozhu Liu; Felix Jose

    2007-01-01

    Here we present data indicating the complexity and highly variable response of barrier islands and beaches to the impacts of tropical cyclones and winter storms along the northern Gulf of Mexico. Data indicate that (1) barrier islands can conserve mass during catastrophic hurricanes; (2) less severe hurricanes and tropical storms can promote rapid dune aggradation and contribute sediment to the

  4. The impact of anthropogenic climate change on North Atlantic tropical cyclone tracks

    NASA Astrophysics Data System (ADS)

    Soden, B. J.; Colbert, A. J.

    2013-05-01

    We examine the change in tropical cyclone (TC) tracks that result from projected changes in the large-scale steering flow and genesis location due to increasing greenhouse gases. Tracks are first simulated using a Beta and Advection Model (BAM) and NCEP-NCAR Reanalysis winds for all TCs that formed in the North Atlantic main development region (MDR) for the period 1950-2010. Changes in genesis location and large-scale steering flow are then estimated from an ensemble mean of 17 CMIP3 models for the A1b emissions scenario. The BAM simulations are then repeated with these changes to estimate how the TC tracks would respond to increased greenhouse gases. As the climate warms, the models project a weakening of the subtropical easterlies as well as an eastward shift in genesis location. This results in a statistically significant decrease in straight-moving (westward) storm tracks of ~5.5% and an increase in recurving (open ocean) tracks of ~5.5%. These track changes decrease TC counts over the Southern Gulf of Mexico and Caribbean by 1-1.5 per decade and increase TC counts over the central Atlantic by 1-1.5 per decade. Changes in the large-scale steering flow account for a vast majority of the projected changes in TC trajectories.

  5. 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

  6. Climatological features of WRF-simulated tropical cyclones over the western North Pacific

    NASA Astrophysics Data System (ADS)

    Kim, Dasol; Jin, Chun-Sil; Ho, Chang-Hoi; Kim, Jinwon; Kim, Joo-Hong

    2014-11-01

    Tropical cyclones (TCs) over the western North Pacific (WNP) are simulated for the 29 TC seasons of July-October from 1982 to 2010 using the regional Weather Research and Forecasting (WRF) model nested within global WRF model simulations. Averaged over the entire 29-year period, the nested global-regional WRF has reasonably simulated the climatology of key TC features such as the location/frequency of genesis and tracks. The dynamical and thermal structures of the simulated TCs are weaker than observations owing to the coarse spatial resolution of the regional WRF (50 km × 50 km). TC frequencies are somewhat underestimated over the East China Sea but are substantially overestimated over the South China Sea and the Philippine Sea with neighboring oceans between 10°N and 15°N. Categorization of the simulated TCs into six clusters based on the observed TC clusters and the associated large-scale circulation show that the nested simulation depicts the observed TC characteristics well except for two clusters associated with TCs traveling from the Philippine Sea to the East China Sea. Errors in the simulated TC genesis and tracks are mostly related to these two clusters. In the simulation, the monsoon confluent zone over the Philippine Sea is too strong, and the mid-latitude jet stream expands farther south than that in the observations. Overall results from this study suggest that the nested global-regional WRF can be useful for studying the TC climatology over the WNP.

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

    NASA Technical Reports Server (NTRS)

    Hall, Timothy; Yonekura, Emmi

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  9. A training course on tropical cyclones over the eastern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Farfan, L. M.; Pozo, D.; Raga, G.; Romero, R.; Zavala, J.

    2008-05-01

    As part of a research project funded by the Inter-American Institute for Global Change Research (IAI), we are performing a short course based on the current understanding of tropical cyclones in the eastern Pacific basin. In particular, we are focused in discussing the formation and intensification off the Mexican coast. Our main goal is to train students from higher-education institutions from selected countries in Latin America. Our approach includes the review of climatological features derived from the best-track dataset issued by the National Hurricane Center. Using this dataset, we built a climatology of relevant positions and storm tracks for the base period 1970-2006. Additionally, we designed hands-on sessions in which students analyze satellite imagery from several platforms (GOES, QuikSCATT and TRMM) along with mesoscale model simulations from the WRF model. Case studies that resulted in landfall over northwestern Mexico are used; this includes Hurricanes John, Lane and Paul all of which developed during the season of 2006. So far, the course has been taught in the Atmospheric Sciences Department at the University of Buenos Aires, Argentina, and in La Paz, Mexico, with students from Mexico, Chile, Brazil, Costa Rica and Cuba.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Recent dramatic increases in damages caused by tropical cyclones (TCs) and improved understanding of the physics of TCs, have led DHS and NOAA to reconsider intentional hurricane modification. We present a decision analytic assessment of whether, and under what circumstances, it might be rational to attempt to lower the wind speed in a TC approaching South Florida by reducing sea surface temperatures using wind-wave pumps. We compare wind damages after storm modification with damages after investing in mitigation strategies that protect buildings. Using historical data on hurricanes approaching the east coast of Florida since 1953, we develop prior probabilities of how model storms might evolve. The effects of modification are estimated using five hundred simulations with 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 find that the effect of natural variability is larger than that of either modification or mitigation. If it were properly implemented, and worked as expected, the modification strategy we study could result in slightly lower net losses from an intense storm than the mitigation options considered. However, for all but the most intense storms, mitigation provides "fail safe" protection that might not always be achieved if the only option were modification. A strategy that combines routine mitigation with occasional modification of very intense storms warrants further study.

  11. A study of the connection between tropical cyclone track and intensity errors in the WRF model

    NASA Astrophysics Data System (ADS)

    Tien, Du Duc; Ngo-Duc, Thanh; Mai, Hoang Thi; Kieu, Chanh

    2013-10-01

    This study examines the dependence of the tropical cyclone (TC) intensity errors on the track errors in the Weather Research and Forecasting (WRF-ARW) model. By using the National Centers for Environmental Prediction global final analysis as the initial and boundary conditions for cloud-resolving simulations of TC cases that have small track errors, it is found that the 2- and 3-day intensity errors in the North Atlantic basin can be reduced to 15 and 19 % when the track errors decrease to 55 and 76 %, respectively, whereas the 1-day intensity error shows no significant reduction despite more than 30 % decrease of the 1-day track error. For the North-Western Pacific basin, the percentage of intensity reduction is somewhat similar with the 2- and 3-day intensity errors improved by about 15 and 19 %, respectively. This suggests that future improvement of the TC track forecast skill in the WRF-ARW model will be beneficial to the intensity forecast. However, the substantially smaller percentages of intensity improvement than those of the track error improvement indicate that ambient environment tends to play a less important role in determining the TC intensity as compared to other factors related to the vortex initialization or physics representations in the WRF-ARW model.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Bay of Bengal: coupling of pre-monsoon tropical cyclones with the monsoon onset in Myanmar

    NASA Astrophysics Data System (ADS)

    Fosu, Boniface O.; Wang, Shih-Yu Simon

    2014-08-01

    The pre-monsoon tropical cyclone (TC) activity and the monsoon evolution in the Bay of Bengal (BoB) are both influenced by the Madden-Julian Oscillation (MJO), but the two do not always occur in unison. This study examines the conditions that allow the MJO to modulate the monsoon onset in Myanmar and TC activity concurrently. Using the APHRODITE gridded precipitation and the ERA-Interim reanalysis datasets, composite evolutions of monsoon rainfall and TC genesis are constructed for the period of 1979-2010. It is found that the MJO exhibits a strong interannual variability in terms of phase and intensity, which in some years modulate the conditions for BoB TCs to shortly precede or form concurrently with the monsoon onset in Myanmar. Such a modulation is absent in years of weaker MJO events. Further understanding of the interannual variability of MJO activity could facilitate the prediction of the monsoon onset and TC formation in the BoB.

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

    PubMed Central

    Tweel, Andrew W.; Turner, R. Eugene

    2012-01-01

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

  15. Tropical cyclone footprint in the ocean mixed layer observed by Argo in the Northwest Pacific

    NASA Astrophysics Data System (ADS)

    Fu, HongLi; Wang, Xidong; Chu, Peter C.; Zhang, Xuefeng; Han, Guijun; Li, Wei

    2014-11-01

    This study systematically investigated the ocean mixed layer responses to tropical cyclone (TC) using available Argo profiles during the period of 1998-2011 in the northwest Pacific. Results reveal that isothermal layer (IL) deepening and isothermal layer (IL) cooling with evident rightward biases induced by strong TCs are clearer compared to the weak TCs. Likewise, the rightward biases of IL deepening and cooling induced by fast TCs are more obvious than that induced by slow TCs. The upwelling within TC's eye is much stronger for the strong (slow) TCs than weak (fast) TCs. For the strong and slow TCs, the TC-induced rainfall reduces deepening of constant density layer (with its depth called the mixed layer depth, MLD), and in turn increases the barrier layer thickness (BLT). The initial BL prior to TC can restrict IL cooling more markedly under the weak and fast TCs than under the strong and slow TCs. The inertial oscillation is stronger induced by the strong (fast) TCs than by the weak (slow) TCs. In addition, the most pronounced TC-induced mixed layer deepening and IL cooling in July to October climatology occur in the subtropical gyre of the northwest Pacific with enhanced vertical diffusivity. The maximum increase of isothermal layer depth (ILD) and MLD is up to 5 m, with IL cooling up to 0.4°C.

  16. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  18. Statistical characteristics and mechanistic analysis of suddenly reversed tropical cyclones over the western North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Luo, Xia; Fei, Jianfang; Huang, Xiaogang; Cheng, Xiaoping; Ding, Juli; He, Yiqiang

    2015-04-01

    Based on best track data of tropical cyclones (TCs) from the Japan Meteorological Agency, the characteristics of suddenly reversed TCs (SRTCs), which have turning angles usually approaching 180°, are statistically analyzed from 1949 to 2011 over the western North Pacific Ocean. The typical large-scale circulation patterns of SRTCs are investigated using reanalysis data and dynamical composite analysis. Results show that turnings mainly occur in low latitudes between 10°N and 20°N, and mainly west of 135°E. The majority of SRTCs reach their peak intensity at, or slightly before, the turning time and subsequently decrease at some variable rate. Specifically, SRTCs are divided into four types, each containing two groups (i.e. eight groups in total) in terms of the moving-direction changes. The moving speed of all SRTC types except the south-north type decreases to its lowest during the 24 h, corresponding to a significant reduction in the primary steering components. According to the analysis of the 13 typical flow patterns found in this study, we suggest that sudden track changes are caused by the reversal steering flow. The original balance of the background flow patterns are broken up by new systems, e.g. binary TCs or dispersion-induced anticyclones. Additionally, sudden track changes are often due to double ridge variations of the subtropical high or weakened/strengthened high pressure in the east and west, respectively.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  1. 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

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

    PubMed

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

    2011-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  6. 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.

  7. Effects of a tropical cyclone on the distribution of hatchery-reared black-spot tuskfish Choerodon schoenleinii determined by acoustic telemetry.

    PubMed

    Kawabata, Y; Okuyama, J; Asami, K; Okuzawa, K; Yoseda, K; Arai, N

    2010-08-01

    The effects of a tropical cyclone on the distribution of hatchery-reared black-spot tuskfish Choerodon schoenleinii were examined using acoustic telemetry. Nine fish were released in Urasoko Bay, Ishigaki Island, Japan, in September 2006, and another nine were released in June to July 2007, before a cyclone's passing through the area in September 2007. Data for the fish released in 2006 were used as the cyclone-inexperienced group to compare their distribution pattern to that of the 2007 cyclone-experienced group. Both groups of fish were monitored for up to 150 days. Of the nine fish in each group, four (44%) and two (22%) were monitored for over 150 days in the cyclone-inexperienced and the cyclone-experienced groups, respectively. Three of the five fish that had settled in the monitoring area left the area within a few days of the cyclone event. To estimate the time of disappearance of the fish, maximum wind speed during a period of 7 days (indicating the occurrence and intensity of the tropical cyclone), fish size and release year were evaluated as explanatory variables using a Cox proportional hazards model with Akaike's information criterion. The best predictive model included the effect of maximum wind speed. One fish that left the monitoring area displayed movement patterns related to strong winds, suggesting that wind-associated strong currents swept the fish away. No relationships were found between the movement patterns of the other two fish and any physical environmental data. The daily detection periods of one of the two fish gradually decreased after the cyclone hit, and this fish eventually left the monitoring area within 3 days, suggesting that it shifted to a habitat outside the monitoring area. These results indicate that tropical cyclones have both direct and indirect effects on the distribution of hatchery-reared C. schoenleinii. PMID:20701644

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  10. Development after Disaster: Multidecadal Impacts of Tropical Cyclones upon Long-run Economic Growth

    NASA Astrophysics Data System (ADS)

    Jina, A.; Hsiang, S. M.

    2012-12-01

    Weather-related disasters lead to immediate costs in the billions of dollars each year, and this loss informs the strategies for disaster mitigation and recovery. However, the causal effect of natural disasters on long-run economic development remains unclear. We reconstruct every country's physical exposure to the universe of tropical cyclones (TCs) during 1950-2008 using the International Best Tracks Archive for Climate Stewardship (IBTrACS) and then exploit year-to-year variation in cyclone strikes to identify the effect of disasters on GDP growth. Linking this economic data to a physical model of TC hazard, we are the first analysis to deconvolve the long-run cumulative impact of year-to-year changes in TC incidence. We reject long-standing hypotheses that disasters stimulate growth via "creative destruction" or that losses disappear following transfers of wealth. Instead, we find robust evidence that national incomes decline, relative to their pre-disaster trend, and do not recover within twenty years. This result is consistent across income sources, regions, countries' geographic size, and income level. Global patterns of climate-based adaptation, in addition to similar long-run changes in consumption, investment, trade and international aid, further corroborate this finding. Consistent with the idea that long-term loans finance the replacement of lost capital, national income loss arises from a small reduction of annual growth rates spread across the decades following disaster. The cumulative effect of this persistently suppressed growth is significant and large: a 90th percentile event reduces per capita incomes by 7.4% two decades later (fig. A). The gradual nature of these losses render them inconspicuous to a casual observer, however simulations indicate that they have dramatic influence over the long-run development of countries that face regular exposure to TCs (fig. B). Our results indicate that the true cost of a disaster may not only be the immediate cost, but also the long-term suppression of growth opportunities within a country. We suggest that it is essential to consider this when estimating the losses associated with a disaster, and plan for it accordingly. This finding transforms our understanding of a society's resilience to disasters, and necessitates a new viewpoint to be considered when we think of weathering natural hazards.;

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

    NASA Astrophysics Data System (ADS)

    Fernandez, I.; Villanoy, C. L.

    2013-12-01

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

  12. Comparison of TRMM precipitation radar and microwave imager rainfall retrievals in tropical cyclone inner cores and rainbands

    NASA Astrophysics Data System (ADS)

    Zagrodnik, Joseph P.; Jiang, Haiyan

    2013-01-01

    Tropical Rainfall Measuring Mission (TRMM) rainfall retrieval algorithms are evaluated in tropical cyclone (TC) inner cores (IC), inner bands (IB), and outer rainbands (OB). In total, 1329 IC, 2149 IB, and 4627 OB storm regions are analyzed using data from a 12-year TRMM Tropical Cyclone Precipitation Feature (TCPF) database containing 1013 TCs viewed from December 1997 to December 2009. Attention is focused on the difference between the Precipitation Radar (PR) 2A25 and the TRMM Microwave Imager (TMI) 2A12 rainfall algorithms. The PR 2A25 produces larger mean rain rates than the TMI 2A12 in inner cores and inner bands, with the greatest difference occurring in hurricanes. This discrepancy is caused mostly by the TMI 2A12 significantly underestimating regions of moderate to heavy rain >15 mm hour-1 or when the PR reflectivity is greater than 30 dBZ. The TMI 2A12 rain rates are most closely related to the percentage coverage of 85 GHz polarization-corrected brightness temperature (PCT) <225 K in the IC and 85 GHz PCT <250 K in the IB and OB. These convective parameters are good predictors of the mean TMI 2A12 rain rate, but significant ice scattering is not always present in areas of heavy rain that are often widespread in TC inner regions. As a result, the TMI 2A12 algorithm may poorly measure the rain rate, particularly in the inner core of hurricanes.

  13. Ionosphere effects of tropical cyclones over the Asian region of Russia according to oblique radio-sounding data

    NASA Astrophysics Data System (ADS)

    Chernigovskaya, Marina A.; Kurkin, Vladimir I.; Oinats, Alexey V.; Poddelsky, Igor N.

    2014-11-01

    The possibility of manifestation of tropical cyclones in variations of ionospheric parameters in the zone far removed from the disturbance source region has been studied. The data from frequency analysis by maximal observed frequencies (MOF) for the oblique sounding (OS) signals were used. We revealed 1-5 h time intervals with higher oscillation energetics along the Norilsk-Irkutsk, Magadan-Irkutsk, and Khabarovsk-Irkutsk paths (Eastern Siberia and the Far East of Russia) during equinoctial periods (March, September 2005-2011), in November, 2005 and in summer 2010-2011 for different periods of the solar cycle. These time intervals may be interpreted as a manifestation of large-scale traveling ionospheric disturbances (TIDs) whose sources are atmospheric internal gravity waves. By jointly analyzing ionospheric, heliomagnetic, atmospheric, and satellite data on tropical cyclones (TCs), we attempted to associate the series of the revealed TIDs with ionospheric responses to TCs over the Western North Pacific Ocean during the above periods. A significant increase in wave disturbances on OS paths was established to be noted during active tropical cyclogenesis periods in autumn months. For spring equinox (March, 2005-2011), we also note TID manifestations in MOF time variations under quiet heliomagnetic conditions and in TC absence, but the intensity of these wave disturbances was significantly lower, than that of autumn seasons for various years. We estimated the wavelike disturbance propagation velocity by the delay time of TID passing the medium points of the spaced OS paths.

  14. Tropical Rain Forest Recovery from Cyclone Damage and Fire in Samoa1

    Microsoft Academic Search

    Johan Hjerpe; Henrik Hedenas; Thomas Elmqvist

    2001-01-01

    In 1990 and 1991, Samoa was struck by two cyclones, Ofa and Val. In the Tafua Rain Forest Preserve on the island of Savai'i, one part of the forest also burned after the first cyclone. Here we report on patterns of regeneration and changes in tree species composition in the Tafua lowland rain forest after five years of recovery from

  15. Seasonal prediction model for summer tropical cyclone track density over the western North Pacific

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Skillful predictions of seasonal tropical cyclone (TC) activity are an important concern in mitigating the potential destruction from TC landfall/approach in many coastal regions. In this study, a new-type model for the prediction of the seasonal TC activity over the western North Pacific is developed to provide useful information on the seasonal characteristic of spatial distribution of TC tracks and the vulnerable areas. The developed model named 'track-pattern-based model' is characterized by two features: 1) the hybrid statistical-dynamical prediction of the seasonal activity of the seven representative track patterns obtained by the fuzzy clustering of historical TC tracks, and 2) the technique to construct a prediction map of the seasonal TC passage. The hybrid statistical-dynamical prediction for each pattern is based on the statistical relations between the seasonal TC frequency of the pattern and the seasonal-mean key predictors dynamically forecasted by the National Centers for Environmental Prediction Climate Forecast System in May. The leave-one-out cross-validation demonstrates good prediction skill with the correlation coefficients between the hindcasts and the observation as large as 0.7 for 1981-2006. Using the predicted frequency and the climatological probability for each pattern, we obtain the forecasting map of the seasonal TC track density by combining the TC track densities of the seven patterns. The hindcasts of the basin-wide seasonal TC track density exhibit a good skill in reproducing the observed pattern. The El Niño- or La Niña-related seasons, in particular, tend to show a better skill than the neutral seasons.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  17. The Bay of Bengal upper-ocean response to tropical cyclone forcing during 1999

    NASA Astrophysics Data System (ADS)

    Wang, Jih-Wang; Han, Weiqing

    2014-01-01

    The regional upper-ocean dynamical and thermodynamical responses to two consecutive, strong tropical cyclones (TCs)—04B (15-19 October) and 05B (25 October to 3 November) in 1999 (hereafter, TC1 and TC2) in the Bay of Bengal (BoB) and the associated oceanic processes are investigated using an eddy-permitting Hybrid Coordinate Ocean Model. The TC winds induce positive sea surface height anomalies (SSHA) along the northern BoB coastline and Andaman Sea due to onshore convergence, and negative SSHA along the TC tracks due to Ekman divergence, which in turn induce geostrophic flow. The TC-associated radiation and precipitation have negligible effects on the northwestern BoB top 30 m averaged temperature (T0-30 m), while the strong TC winds significantly enhance turbulent heat flux causing T0-30 m decrease. Due to the existence of the barrier layer and subsurface warm advection in the northwestern BoB, vertical mixing may induce near-surface warming by entraining warm water from below. As a result, the proportion of the T0-30 m cooling caused by turbulent heat flux is likely elevated in the 6° × 6° footprints of the TCs. Both TC wind-induced vertical mixing and upwelling significantly cool T0-30 m in TC1's wake, while upwelling dominates the maximum cooling region in TC2's wake, likely due to the preceding deepening of the mixed layer by TC1. The near-surface cooling for both TCs has rightward bias because of the higher winds and the resonant response on the right, and Ekman divergence extends the cooling areas outward. TC1 and TC2's sizes and prestorm oceanic conditions are found to be the most influential factors for near-surface cooling.

  18. Sensitivity of Tropical Cyclones to Parameterized Convection in the NASA GEOS5 Model

    NASA Technical Reports Server (NTRS)

    Lim, Young-Kwon; Schubert, Siegfried D.; Reale, Oreste; Lee, Myong-In; Molod, Andrea M.; Suarez, Max J.

    2014-01-01

    The sensitivity of tropical cyclones (TCs) to changes in parameterized convection is investigated to improve the simulation of TCs in the North Atlantic. Specifically, the impact of reducing the influence of the Relaxed Arakawa-Schubert (RAS) scheme-based parameterized convection is explored using the Goddard Earth Observing System version5 (GEOS5) model at 0.25 horizontal resolution. The years 2005 and 2006 characterized by very active and inactive hurricane seasons, respectively, are selected for simulation. A reduction in parameterized deep convection results in an increase in TC activity (e.g., TC number and longer life cycle) to more realistic levels compared to the baseline control configuration. The vertical and horizontal structure of the strongest simulated hurricane shows the maximum lower-level (850-950hPa) wind speed greater than 60 ms and the minimum sea level pressure reaching 940mb, corresponding to a category 4 hurricane - a category never achieved by the control configuration. The radius of the maximum wind of 50km, the location of the warm core exceeding 10 C, and the horizontal compactness of the hurricane center are all quite realistic without any negatively affecting the atmospheric mean state. This study reveals that an increase in the threshold of minimum entrainment suppresses parameterized deep convection by entraining more dry air into the typical plume. This leads to cooling and drying at the mid- to upper-troposphere, along with the positive latent heat flux and moistening in the lower-troposphere. The resulting increase in conditional instability provides an environment that is more conducive to TC vortex development and upward moisture flux convergence by dynamically resolved moist convection, thereby increasing TC activity.

  19. An investigation into aggregate vs. occurrence losses for European extra-tropical cyclones

    NASA Astrophysics Data System (ADS)

    Latchman, Shane; Higgs, Stephanie

    2013-04-01

    Catastrophe models are tools used primarily by the insurance industry to quantify the potential financial impact of natural disasters. Two key outputs from a catastrophe model are the aggregate and occurrence losses by return period. Aggregate losses are the total losses in any given windstorm season whereas occurrence losses are the maximum losses in a given windstorm season. Robust cat models for the European extra tropical cyclone catalogue allow for aggregate losses to be larger than occurrence losses particularly because there tend to be several ETC events in a given winter season and hence a notable difference between the largest loss and the total loss. Such information is vital to informing the purchase of reinstatements on a reinsurance program since knowledge of whether a large loss in a year is likely to be say twice the maximum limit purchased by an insured can determine whether that insured is adequately protected in the event of a series of large catastrophe losses in a given year. Such information therefore can help companies stay solvent and ultimately provides a social benefit through ensuring policyholders affected by disasters will be paid by their still solvent insurance companies. This paper describes the relationship between aggregate and occurrence losses both historically and as obtained from a cat model. The analysis shows that the aggregate/occurrence ratio tends to be higher for larger countries and lower as the return period under consideration increases. Also the aggregate/occurrence ratio tends to decrease when moving from Atlantic coast countries to those in central Europe.

  20. Aspects of Observed Gust Factors in Landfalling Tropical Cyclones: Gust Components, Terrain, and Upstream Fetch Effects

    NASA Astrophysics Data System (ADS)

    Miller, Craig; Balderrama, Juan-Antonio; Masters, Forrest

    2015-04-01

    Using wind-speed records from mobile weather stations deployed in tropical cyclones making landfall along the United States coastline over the period 1998-2008, an analysis was made of the gust factors observed in near-neutral conditions by station site and wind direction. The dataset used contained a total of 56 individual station site/wind-direction combinations representative of a wide variety of terrain conditions, ranging from open water to urban exposures. Consideration of the peak gust measured along a given axis, together with the associated components measured simultaneously along the other two axes, showed that peak along-wind gusts are primarily associated with vertical velocities in air moving towards the surface, while peak downwards and upwards vertical gusts are associated with along-wind velocity components that are respectively larger and smaller than the mean along-wind velocity. This behaviour is directly related to the value of the primary component of the surface shear stress in the coordinate system used for the analysis, which involves the product of the along-wind and vertical velocity components and which must be negative in the surface layer. Grouping the mean gust-factor curves for each velocity component into bins based on the turbulence intensity showed that the individual curves in a given bin could not all be considered to be drawn from the same underlying parent distribution, an observation that was confirmed by statistical testing. A quantitative exploration of the effects of upstream terrain variations on the observed gust factors for a selected number of sites suggested that the gust factors and other flow parameters, such as the turbulence intensity, are heavily influenced by the upstream terrain at many of the station sites considered.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  2. Tropical Cyclones' influence on the ocean: from event scale processes to climate scale consequences

    NASA Astrophysics Data System (ADS)

    Vincent, E. M.; Lengaigne, M.; Vialard, J.; Madec, G.; Emanuel, K.

    2013-12-01

    Strong winds associated with Tropical Cyclones (TCs) trigger intense mixing in the upper ocean. The associated sub-surface warming has been suggested to substantially modify the ocean heat budget. A 1/2° global ocean model experiment that realistically samples the ocean response to more than 3,000 TCs over the last 30 years is used to investigate the processes induced by TCs at the local scale and their impact on the ocean at the climate scale. Vertical mixing is the dominant process explaining surface cooling close to the TCs' track. This process has received the largest attention from previous studies investigating the climatic importance of TC-ocean interaction, but surface cooling is increasingly due to heat fluxes as we consider larger space scales. Vertical mixing does induce an enhanced ocean heat uptake (OHU) consistent with previous estimates. However, two processes have to be taken into account when evaluating the importance of this OHU for climate: 1) about 1/3 of the ocean heat uptake is in fact used to compensate ocean heat loss by enhanced surface fluxes due to TCs, 2) most of the remaining heat injected into the ocean during TC seasons is re-entrained by the deepening of the mixed layer in fall and winter. As a consequence, the main TCs' climatological impact is to reduce the amplitude of surface temperature seasonal cycle more than to modify the ocean heat transport. (a) Composite time series of TC-induced total surface flux anomalies within 600 km of TC-tracks. Ocean heat extracted=TC-induced heat fluxes to the atmosphere during TCs passage. Ocean heat uptake=heat input from the atmosphere needed to dissipate the cold wake. Ocean heat release=subsurface anomalies re-emerging during the next winter. Ocean Heat Transport=part of these subsurface anomalies transported laterally before re-emerging. (b) Total heat uptake by the ocean (OHU) in the wake of TCs and its partition into various components

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  4. The Impact of the AMO on North Atlantic Tropical Cyclone Activity in the 21st Century

    NASA Astrophysics Data System (ADS)

    LaRow, T.; Stefanova, L. B.

    2013-05-01

    In the North Atlantic Ocean, tropical cyclone (TC) activity exhibits a quasi multidecadal cycle with large interannual variability superimposed on the low frequency multidecadal TC cycle. The cause of the low frequency multidecadal TC cycle is not completely understood and there is scientific debate as to whether or not the observed increase in measures of Atlantic TC activity in past decades is attributable to increased SSTs caused by anthropogenic forcing, is part of a natural low frequency cycle, or perhaps some combination of both. One low frequency SST mode of variability in the North Atlantic is the Atlantic Multidecadal Oscillation (AMO). The AMO is approximately a 70-year cycle of North Atlantic SSTs with about a 0.49°C range in temperature which is larger than either the range in interannual to decadal variability (0.46°C) or the trend from 1870-1999 (0.38°C). Prediction of the AMO, due to a combination of its unforced nature and model imperfections, is only possible to some degree for the nearest decade, or in a probabilistic sense. Statistical analysis shows that during the positive phase of the AMO, North Atlantic hurricane activity tends to be enhanced, especially major hurricanes. In this study, we examine TC activity in two 20-yr time periods (2020-2039 and 2080-2099) using SSTs from the CMIP5 RCP4.5 scenario simulation as prescribed lower boundary conditions in the FSU/COAPS atmospheric general circulation model. The AMO signal from the CMIP5 SSTs is removed and replaced with the observed maximum positive and negative amplitude phases of the AMO obtained from the HadISST dataset. Examination of the impacts of the AMO phases and anthropogenic warming on future TC activity will be discussed.

  5. Convective Asymmetries Associated with Tropical Cyclone Landfall. Part I: f-Plane Simulations.

    NASA Astrophysics Data System (ADS)

    Chan, Johnny C. L.; Liang, Xudong

    2003-07-01

    This study investigates the physical processes associated with changes in the convective structure of a tropical cyclone (TC) during landfall using the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model, version 3 (MM5). The land surface is moved toward a spunup vortex at a constant zonal speed on an f plane. Four experiments are carried out with the following fluxes modified over land: turning off sensible heat flux, turning off moisture flux, setting a higher surface roughness, and combining the last two processes.The results suggest that sensible heat flux appears to show no appreciable effect while moisture supply is the dominant factor in modifying the convective structure. Prior to landfall, maximum precipitation is found to the front and left quadrants of the TC but to the front and right quadrants after landfall when moisture is turned off and surface roughness increased.To understand the physical processes involved, a conceptual experiment is carried out in which moisture supply only occurs over the ocean and at the lowest level of the atmosphere, and such supply is transported around by the averaged circulation of the TC. It is shown that the dry air over land is being advected up and around so that at some locations the stability of the atmosphere is reduced. Analyses of the data from the more realistic numerical experiments demonstrate that convective instability is indeed largest just upstream of where the maximum rainfall occurs. In other words, the effect of the change in moisture supply on the convection distribution during TC landfall is through the modification of the moist static stability of the atmosphere.

  6. Observation and a numerical study of gravity waves during tropical cyclone Ivan (2008)

    NASA Astrophysics Data System (ADS)

    Chane Ming, F.; Ibrahim, C.; Barthe, C.; Jolivet, S.; Keckhut, P.; Liou, Y.-A.; Kuleshov, Y.

    2014-01-01

    Gravity waves (GWs) with horizontal wavelengths of 32-2000 km are investigated during tropical cyclone (TC) Ivan (2008) in the southwest Indian Ocean in the upper troposphere (UT) and the lower stratosphere (LS) using observational data sets, radiosonde and GPS radio occultation data, ECMWF analyses and simulations of the French numerical model Meso-NH with vertical resolution < 150 m near the surface and 500 m in the UT/LS. Observations reveal dominant low-frequency GWs with short vertical wavelengths of 0.7-3 km, horizontal wavelengths of 80-400 km and periods of 4.6-13 h in the UT/LS. Continuous wavelet transform and image-processing tools highlight a wide spectrum of GWs with horizontal wavelengths of 40-1800 km, short vertical wavelengths of 0.6-3.3 km and periods of 20 min-2 days from modelling analyses. Both ECMWF and Meso-NH analyses are consistent with radiosonde and GPS radio occultation data, showing evidence of a dominant TC-related quasi-inertia GW propagating eastward east of TC Ivan with horizontal and vertical wavelengths of 400-800 km and 2-3 km respectively in the LS, more intense during TC intensification. In addition, the Meso-NH model produces a realistic, detailed description of TC dynamics, some high-frequency GWs near the TC eye, variability of the tropospheric and stratospheric background wind and TC rainband characteristics at different stages of TC Ivan. A wave number 1 vortex Rossby wave is suggested as a source of dominant inertia GW with horizontal wavelengths of 400-800 km, while shorter scale modes (100-200 km) located at northeast and southeast of the TC could be attributed to strong localized convection in spiral bands resulting from wave number 2 vortex Rossby waves. Meso-NH simulations also reveal GW-related clouds east of TC Ivan.

  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

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

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

    NASA Astrophysics Data System (ADS)

    Uhlhorn, E. W.; Klotz, B.

    2012-12-01

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

  9. Mapping the world's tropical cyclone rainfall contribution over land using TRMM satellite data: precipitation budget and extreme rainfall

    NASA Astrophysics Data System (ADS)

    Prat, O. P.; Nelson, B. R.

    2012-12-01

    A study was performed to characterize over-land precipitation associated with tropical cyclones (TCs) for basins around the world gathered in the International Best Track Archive for Climate Stewardship (IBTrACS). From 1998 to 2010, rainfall data from TRMM 3B42, showed that TCs accounted for 8-, 11-, 7-, 10-, and 12-% of the annual over-land precipitation for North America, East Asia, Northern Indian Ocean, Australia, and South-West Indian Ocean respectively, and that TC-contribution decreased importantly within the first 150-km from the coast. At the local scale, TCs contributed on average to more than 40% and up to 77% of the annual precipitation budget over very different climatic areas with arid or tropical characteristics. The East Asia domain presented the higher and most constant TC-rain (170±23%-mm/yr) normalized over the area impacted, while the Southwest Indian domain presented the highest variability (130±48%-mm/yr), and the North American domain displayed the lowest average TC-rain (77±27%-mm/yr) despite a higher TC-activity. The maximum monthly TC-contribution (11-15%) was found later in the TC-season and was a conjunction between the peak of TC-activity, TC-rainfall, and the domain annual antagonism between dry and wet regimes if any. Furthermore, TC-days that accounted globally for 2±0.5% of all precipitation events for all basins, represented between 11-30% of rainfall extremes (>101.6mm/day). Locally, TC-rainfall was linked with the majority (>70%) or the quasi-totality (?100%) of extreme rainfall. Finally, because of their importance in terms of rainfall amount, the contribution of tropical cyclones is provided for a selection of fifty urban areas experiencing cyclonic activity. Cases studies conducted at the regional scale will focus on the link between TC-activity, water resources, and hydrohazards such as floods and droughts.

  10. Turbulence Spectra for Boundary-Layer Winds in Tropical Cyclones: A Conceptual Framework and Field Measurements at Coastlines

    NASA Astrophysics Data System (ADS)

    Li, Lixiao; Kareem, Ahsan; Hunt, Julian; Xiao, Yiqing; Zhou, Chaoying; Song, Lili

    2015-02-01

    A conceptual model is proposed for the characteristic sub-ranges in the velocity and temperature spectra in the boundary layer of tropical cyclones (hurricanes or typhoons). The model is based on observations and computation of radial and vertical profiles of the mean flow and turbulence, and on the interpretation of eddy mechanisms determined by shear (namely roll and streak structures near the surface), convection, rotation, blocking and sheltering effects at the ground/sea surface and in internal shear layers. The significant sub-ranges, as the frequency increases, are associated with larger energy containing eddies, shear and blocking, inertial transfer between large and small scales, and intense small-scale eddies generated near the surface caused by waves, coastal roughness change, and the buoyancy force associated with the evaporation of spray droplets. These sub-ranges vary with the locations at which the spectra are measured, i.e. the level in relation to the height of the peak mean velocity and the depth of the boundary layer, and the radius in relation to the eyewall radius and the outer-vortex radius . For two tropical cyclones (Nuri and Hagupit), experimental data were analyzed. Spectra were measured where is near to and using four 1-h long datasets at coastal towers, at 10- and 60-m heights for tropical cyclone Nuri, and at 60-m height for tropical cyclone Hagupit at the south China coast. The field measurements of spectra within the boundary layer show significant sub-ranges of self-similar energy spectra (lying between the length scale 1,000 m and the smallest scales less than 40 m) that are consistent with the above conceptual model of the surface layer. However, with very high wind speeds near the eyewall, the energy of the independently generated intense surface eddy motions, associated with surface waves and water droplets in the airflow, greatly exceeds the energies of the small scales in the inertial sub-range of the boundary layer, over scales less than about 3-40 m depending on the height and the radius . This rise in the small-scale frequency weighted spectra (, where is natural frequency, and is the energy spectrum of the longitudinal wind component) is consistent with the hypothesis that these processes are only weakly correlated with the main boundary-layer turbulence.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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