WorldWideScience

Sample records for world-wide tropical cyclones

  1. Tropical Cyclone Report, 1993

    Science.gov (United States)

    1993-01-01

    1IW TS OFELIA 25 U0:. - 25 Jo., 12 45 (23) 99. 12W TY PERCY 27 Jl:. - 30 J(J. :2 6,5 (33) 9/6 13W TY ROBYN 0: AUG - ]C AUG 38 120 (6) 922 14W TY STEVE...westward very small tropical cyclones, Ofelia (llW) and track, and for its inability to intensify beyond 30 Percy (12W), formed in quick succession at...The monsoon gyre of July 1993 was associated with the formation of two and the motion of three very small tropical cyclones: Nathan, Ofelia (11W

  2. Assessing Tropical Cyclone Damage

    Science.gov (United States)

    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).

  3. Tropical Cyclone Report, 1988

    Science.gov (United States)

    1988-01-01

    picture) the comma shape of Tropical Storm Irma (15W). These two tropical cyclones were active with Tropical Storm Jeff (16W) and Typhoon Uleki (01C...DDGM (WF) ESCAP LIBRARY, BANGKOK JAPAN METEOROLOGY AGENCY FLENUMOCEANCEN MONTEREY MCAS IWAKUNI FLORIDA STATE UNIVERSITY NATIONAL HURRICANE CENTER, MIAMI...TY ULEKI ROGERS/SCOVIL 88 (03W) TD 03W PICKLE 40 (15W) TS IRMA CROSBY 93 (04W) TY THAD SCOVIL 44 (16W) TS JEFF PICKLE 94 (05W) TS VANESSA SCHULTZ 48

  4. Tropical Cyclone Report

    Science.gov (United States)

    1989-01-01

    GUARD 160 (13-14W)TS KEN-LOLA BOUCHARD 86 (32W) TY GAY CRITTENDEN 166 (15W) TY MAC BOUCHARD 92 (33W) TY HUNT SHOEMAKER 172 (16W) TY OWEN CRITTENDEN 98...GURAL 188 TC 02A BOUCHARD 190 TC 32W ( GAY ) CRI’TTENDEN 166 4. SUMMARY OF SOUTH PACIFIC AND SOUTH INDIAN OCEAN TROPICAL CYCLONES ............. 193 4.1...Commander Naval ICAO International Civil Aviation AFB Air Force Base Oceanography Command Organization AFGWC Air Force Global Weather COSM or INIT Initial

  5. Tropical Cyclone Information System

    Science.gov (United States)

    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.

  6. Tropical Cyclone Ensemble Data Assimilation

    Science.gov (United States)

    2012-09-30

    B.W. and R.S. Dunbar, 2010: A neural network technique for improving...in artifically higher winds. In high wind conditions (e.g., near the center of tropical cyclones), rain decreases the backscatter signal, because

  7. JPL Tropical Cyclone Information System

    Data.gov (United States)

    National Aeronautics and Space Administration — The JPL Tropical Cyclone Information System (TCIS) brings together satellite and in situ data sets from various sources to help you find information for a particular...

  8. Black Swan Tropical Cyclones

    Science.gov (United States)

    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

  9. Year 2001 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2001 Tropical Cyclones of the World poster. During calendar year 2001, fifty tropical cyclones with sustained surface winds of at least 64 knots were observed...

  10. 2003 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2003 Tropical Cyclones of the World poster. During calendar year 2003, fifty-one tropical cyclones with sustained surface winds of at least 64 knots were...

  11. Year 2000 Tropical Cyclones of the World

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Year 2000 Tropical Cyclones of the World poster. During calendar year 2000, forty-five tropical cyclones with sustained surface winds of at least 64 knots were...

  12. APR-2 Tropical Cyclone Observations

    Science.gov (United States)

    Durden, S. L.; Tanelli, S.

    2011-01-01

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

  13. The Dynamics of Tropical Cyclones

    Science.gov (United States)

    1999-09-30

    interpreted and compared. Lectures on this work have been given by the PI at James Cook University in Townsville, the Australian Bureau of Meteorology Regional...continued to collaborate with Dr. Noel Davidson of the Bureau of Meteorology Research Centre (BMRC) to improve the Bureau’s Tropical Limited-Area Prediction...from the Tropical Cyclone Motion Experiment (TCM90), the European Centre for Medium Range Weather Forecasts, and the Australian Bureau of Meteorology (BoM

  14. Statistical modelling of tropical cyclone tracks: modelling cyclone lysis

    OpenAIRE

    Hall, Tim; Jewson, Stephen

    2005-01-01

    We describe results from the fifth stage of a project to build a statistical model of tropical cyclone tracks. The previous stages considered genesis and the shape of tracks. We now consider in more detail how to represent the lysis (death) of tropical cyclones. Improving the lysis model turns out to bring a significant improvement to the track model overall.

  15. An empirical framework for tropical cyclone climatology

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Nam-Young [Korea Meteorological Administration, Seoul (Korea, Republic of); Florida State University, Tallahassee, FL (United States); Elsner, James B. [Florida State University, Tallahassee, FL (United States)

    2012-08-15

    An empirical approach for analyzing tropical cyclone climate is presented. The approach uses lifetime-maximum wind speed and cyclone frequency to induce two orthogonal variables labeled ''activity'' and ''efficiency of intensity''. The paired variations of activity and efficiency of intensity along with the opponent variations of frequency and intensity configure a framework for evaluating tropical cyclone climate. Although cyclone activity as defined in this framework is highly correlated with the commonly used exponent indices like accumulated cyclone energy, it does not contain cyclone duration. Empirical quantiles are used to determine threshold intensity levels, and variant year ranges are used to find consistent trends in tropical cyclone climatology. In the western North Pacific, cyclone activity is decreasing despite increases in lifetime-maximum intensity. This is due to overwhelming decreases in cyclone frequency. These changes are also explained by an increasing efficiency of intensity. The North Atlantic shows different behavior. Cyclone activity is increasing due to increasing frequency and, to a lesser extent, increasing intensity. These changes are also explained by a decreasing efficiency of intensity. Tropical cyclone trends over the North Atlantic basin are more consistent over different year ranges than tropical cyclone trends over the western North Pacific. (orig.)

  16. Tropical cyclone statistics in the Northeastern Pacific

    OpenAIRE

    Romero Vadillo, E; Zaitsev, Oleg; Morales Pérez., R

    2007-01-01

    The principal area of tropical cyclogenesis in the tropical eastern Pacific Ocean is offshore in the Gulf of Tehuantepec, between 8 and 15° N, and most of these cyclones move towards the west and northwest during their initial phase. Historical analysis of tropical cyclone data in the Northeastern (NE) Pacific over the last 38 years (from 1966 to 2004) shows a mean of 16.3 tropical cyclones per year, consisting of 8.8 hurricanes and 7.4 tropical storms. The analysis shows great geographical v...

  17. Tropical cyclone boundary layer shocks

    OpenAIRE

    Slocum, Christopher J.; Williams, Gabriel J.; Taft, Richard K.; Wayne H. Schubert

    2014-01-01

    This paper presents numerical solutions and idealized analytical solutions of axisymmetric, $f$-plane models of the tropical cyclone boundary layer. In the numerical model, the boundary layer radial and tangential flow is forced by a specified pressure field, which can also be interpreted as a specified gradient balanced tangential wind field $v_{\\rm gr}(r)$ or vorticity field $\\zeta_{\\rm gr}(r)$. When the specified $\\zeta_{\\rm gr}(r)$ field is changed from one that is radially concentrated i...

  18. Annual Tropical Cyclone Report 1980

    Science.gov (United States)

    1980-01-01

    m - mm - 330 t00 12 00 00 00 ~ 0 21 22 23 24 JULY FIGURE 3-11-1. Time o.ws-seci o, KiOY’a mirimrn aca-tevet c- esate va~sus 700 =b equiivetetA pcten...ca Yj org~ujima W sation. 479121 ;:; 95 . 4 ~~The numerical forecast series during this (176 kn cthat o4 Taipei real . peak irter-sity oi (2period...phenomenon that is not evident to the fore- caster in real -time but which explains the motion or character of a tropical cyclone. In- culation pattern

  19. Promoting the confluence of tropical cyclone research.

    Science.gov (United States)

    Marler, Thomas E

    2015-01-01

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

  20. Global trends in tropical cyclone risk

    Science.gov (United States)

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

    2012-04-01

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

  1. Tall precipitation cells in tropical cyclone eyewalls are associated with tropical cyclone intensification

    Science.gov (United States)

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

    2004-12-01

    The association of tall precipitation with tropical cyclone intensification may have implications for the difficult task of forecasting the destructive potential of tropical cyclones. This study uses all of the well-centered overflights of tropical cyclones from 1998 to 2003 seen by the TRMM Precipitation Radar. The chance of intensification increases when one or more extremely tall convective towers exist in the tropical cyclone's eyewall. We define an extremely tall convective tower as a convective cell with a 20 dBZ reflectivity signal that reaches an altitude of at least 14.5 km. In addition, we adapt this radar technique for use with more plentiful infrared and passive microwave data.

  2. Human Influence on Tropical Cyclone Intensity

    Science.gov (United States)

    Sobel, Adam H.; Camargo, Suzana J.; Hall, Timothy M.; Lee, Chia-Ying; Tippett, Michael K.; Wing, Allison A.

    2016-01-01

    Recent assessments agree that tropical cyclone intensity should increase as the climate warms. Less agreement exists on the detection of recent historical trends in tropical cyclone intensity.We interpret future and recent historical trends by using the theory of potential intensity, which predicts the maximum intensity achievable by a tropical cyclone in a given local environment. Although greenhouse gas-driven warming increases potential intensity, climate model simulations suggest that aerosol cooling has largely canceled that effect over the historical record. Large natural variability complicates analysis of trends, as do poleward shifts in the latitude of maximum intensity. In the absence of strong reductions in greenhouse gas emissions, future greenhouse gas forcing of potential intensity will increasingly dominate over aerosol forcing, leading to substantially larger increases in tropical cyclone intensities.

  3. NASA CYGNSS Tropical Cyclone Mission

    Science.gov (United States)

    Ruf, Chris; Atlas, Robert; Majumdar, Sharan; Ettammal, Suhas; Waliser, Duane

    2017-04-01

    The NASA Cyclone Global Navigation Satellite System (CYGNSS) mission consists of a constellation of eight microsatellites that were launched into low-Earth orbit on 15 December 2016. Each observatory carries a four-channel bistatic scatterometer receiver to measure near surface wind speed over the ocean. The transmitter half of the scatterometer is the constellation of GPS satellites. CYGNSS is designed to address the inadequacy in observations of the inner core of tropical cyclones (TCs) that result from two causes: 1) much of the TC inner core is obscured from conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands; and 2) the rapidly evolving (genesis and intensification) stages of the TC life cycle are poorly sampled in time by conventional polar-orbiting, wide-swath surface wind imagers. The retrieval of wind speed by CYGNSS in the presence of heavy precipitation is possible due to the long operating wavelength used by GPS (19 cm), at which scattering and attenuation by rain are negligible. Improved temporal sampling by CYGNSS is possible due to the use of eight spacecraft with 4 scatterometer channels on each one. Median and mean revisit times everywhere in the tropics are 3 and 7 hours, respectively. Wind speed referenced to 10m height above the ocean surface is retrieved from CYGNSS measurements of bistatic radar cross section in a manner roughly analogous to that of conventional ocean wind scatterometers. The technique has been demonstrated previously from space by the UK-DMC and UK-TDS missions. Wind speed is retrieved with 25 km spatial resolution and an uncertainty of 2 m/s at low wind speeds and 10% at wind speeds above 20 m/s. Extensive simulation studies conducted prior to launch indicate that there will be a significant positive impact on TC forecast skill for both track and intensity with CYGNSS measurements assimilated into HWRF numerical forecasts. Simulations of CYGNSS spatial and temporal sampling

  4. Cyclone Center: Can Citizen Scientists Improve Tropical Cyclone Intensity Records?

    OpenAIRE

    Hennon, Christopher H.; Knapp, Kenneth R.; Carl J Schreck III; Stevens, Scott E.; Kossin, James P.; Thorne, Peter; Hennon, Paula; Kruk, Michael C.; Rennie, Jared; Gadéa, Jean-Maurice; Striegl, Maximilian; Carley, Iam

    2015-01-01

    The global tropical cyclone (TC) intensity record, even in modern times, is uncertain because the vast majority of storms are only observed remotely. Forecasters determine the maximum wind speed using a patchwork of sporadic observations and remotely sensed data. A popular tool that aids forecasters is the Dvorak technique—a procedural system that estimates the maximum wind based on cloud features in IR and/or visible satellite imagery. Inherently, the application of the Dvorak procedure is o...

  5. Reanalyzing Tropical Cyclone Intensities with Citizen Scientists

    Science.gov (United States)

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

    2012-12-01

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

  6. A tropical cyclone application for virtual globes

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Lin, Yanluan; Zhao, Ming; Zhang, Minghua

    2015-03-12

    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.

  8. On the movement of tropical cyclone LEHAR

    Science.gov (United States)

    Dasari, Hari Prasad; V, Brahmananda Rao; SSVS, Ramakrishna; Gunta, Paparao; N, Nanaji Rao; P, Ramesh Kumar

    2017-12-01

    In this paper, an attempt has been made to delineate the physical processes which lead to the westward movement of the North Indian Ocean tropical cyclone LEHAR. The Advanced Weather Research and Forecasting (ARW) model is used to simulate LEHAR with 27 and 9 km resolutions. The results indicate that the model performed well in simulating the characteristics of cyclone compared with the Satellite and other observations. In addition to that all terms of the complete vorticity equation are computed to obtain the contribution of each term for the vorticity tendency. The vorticity tendency is calculated in four sectors, namely northwest, northeast, southwest and southeast and assumed that the cyclone moves from its existing location to the nearest point where the vortices tendency is maximum. It is noticed that the vorticity stretching term contributes most to the positive vorticity tendency. The second highest contribution is from the horizontal advection thus indicating the secondary importance of steering. The distribution of lightening flash rates also showing that the flash rates are higher in the SW and followed by NW sectors of the cyclone indicate more strong convective clouds are in SW sector. The equivalent potential temperatures ( θ e) at different stages of before, during and after the mature stage of the cyclone are also analysed and the analysis reveals that the wind-induced surface heat (WISH) exchange process is a plausible mechanism for the intensification of LEHAR.

  9. On the movement of tropical cyclone LEHAR

    KAUST Repository

    Dasari, Hari Prasad

    2017-11-09

    In this paper, an attempt has been made to delineate the physical processes which lead to the westward movement of the North Indian Ocean tropical cyclone LEHAR. The Advanced Weather Research and Forecasting (ARW) model is used to simulate LEHAR with 27 and 9 km resolutions. The results indicate that the model performed well in simulating the characteristics of cyclone compared with the Satellite and other observations. In addition to that all terms of the complete vorticity equation are computed to obtain the contribution of each term for the vorticity tendency. The vorticity tendency is calculated in four sectors, namely northwest, northeast, southwest and southeast and assumed that the cyclone moves from its existing location to the nearest point where the vortices tendency is maximum. It is noticed that the vorticity stretching term contributes most to the positive vorticity tendency. The second highest contribution is from the horizontal advection thus indicating the secondary importance of steering. The distribution of lightening flash rates also showing that the flash rates are higher in the SW and followed by NW sectors of the cyclone indicate more strong convective clouds are in SW sector. The equivalent potential temperatures (θe) at different stages of before, during and after the mature stage of the cyclone are also analysed and the analysis reveals that the wind-induced surface heat (WISH) exchange process is a plausible mechanism for the intensification of LEHAR.

  10. Assessment of Tropical Cyclone Structure Variability

    Science.gov (United States)

    2013-09-01

    triangles , squares, pentagons, and hexagons (Lewis and Hawkins 1982). 17 Asymmetric convection in the inner core of a tropical cyclone is most often...Atlantic for 84 h before turning poleward east of the Lesser Antilles and passing just west of Bermuda on 5 September. H*Wind analyses for Fabian became...available at 1330 UTC 1 September and at regular incre- ments until 0130 UTC 6 September after the storm passed west of Bermuda . At 0730 UTC 4

  11. Ensemble Prediction of Tropical Cyclone Genesis

    Science.gov (United States)

    2017-02-23

    an environment with a near bottom vortex (EBV) and an environment with a mid-level vortex (EMV). The genesis time for each model run will be...predictors are further filtered by Bayesian Information Criterion (BIC) to obtain prediction models which have optimal combinations of predictors. The...efficiency: Mid-level versus bottom vortex Cloud resolving WRF model is used to investigate the tropical cyclone genesis efficiency in an

  12. Lagrangian vortices in developing tropical cyclones

    OpenAIRE

    Rutherford, B.; T. J. Dunkerton; M. T. Montgomery

    2015-01-01

    The article of record as published may be found at http://dx.doi.org/10.1002/qj.2616 Tracking pre-genesis tropical cyclones is important for earlier detection of developing systems as well as targeting potential locations for dropsondes in field experiments. The use of a reference frame moving with the disturbance gives a more accurate depiction of streamlines and closed circulation than the Earth-relative frame. However, identification of recirculating regions does not req...

  13. Toward Clarity on Understanding Tropical Cyclone Intensification

    Science.gov (United States)

    2015-08-01

    thermodynamic pathways through which relatively dry air may be entrained into the moist en- velope region of the vortex. These pathways are in- trinsically... simulated TCs [tropical cyclones; our insertion] as the combined response of a balanced vortex to heating and friction, and this casts doubt on...methodology to cast doubt on the boundary layer spinup mechanism. Echoing the sentiment expressed byDavis andEmanuel, our ability to simulate a phenomenon

  14. Tropical cyclone statistics in the Northeastern Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Vadillo, E. [Universidad Autonoma de Baja California Sur (UABCS), La Paz, Baja California Sur (Mexico); Zaytsev, O. [Centro Interdisciplinario de Ciencias Marinas, Instituto Politecnico Nacional, La Paz, Baja California Sur (Mexico)]. E-mail: ozaytsev@ipn.mx; Morales-Perez, R. [Instituto Mexicano de Tecnologia del Agua (IMTA), Jiutepec, Morelos (Mexico)

    2007-04-15

    The principal area of tropical cyclogenesis in the tropical eastern Pacific Ocean is offshore in the Gulf of Tehuantepec, between 8 and 15 degrees Celsius N, and most of these cyclones move towards the west and northwest during their initial phase. Historical analysis of tropical cyclone data in the Northeastern (NE) Pacific over the last 38 years (from 1966 to 2004) shows a mean of 16.3 tropical cyclones per year, consisting of 8.8 hurricanes 198 and 7.4 tropical storms. The analysis shows great geographical variability of cyclone tracks, and that there were a considerable number of hurricane strikes along the Mexican coast. About 50% of the tropical cyclones formed turned north to northeast. It was rare that any passed further north than 30 degrees Celsius N in latitude because of the cold California Current. Hurricane tracks that affected the NE Pacific may be separated into 5 groups. We compared the historical record of the sea surface temperature (SST), related with the El Nino events with a data set of tropical cyclones, including frequency, intensity, trajectory, and duration. Although the statistical dependence between the frequencies of tropical cyclones of the most abundant categories, 1 and 2, over this region and SST data was not convincing, the percentage of high intensity hurricanes and hurricanes with a long life-time (greater than 12 days) was more during El Nino years than in non-El Nino years. [Spanish] La principal region de la formacion de ciclones en el oceano Pacifico Este es el Golfo de Tehuantepec, entre los 8 y los 15 grados Celsius N. En su fase inicial los ciclones se mueven hacia el oeste y el noroeste. El analisis historico de los ciclones que se han generado durante los ultimos 38 anos (de 1966 a 2004) muestra un promedio de 16.2 ciclones por ano, consistentes en 8.8 huracanes y 7.4 tormentas tropicales. El analisis muestra una gran variabilidad geografica en la trayectoria de los ciclones, de los cuales un gran numero impacta las

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

    Science.gov (United States)

    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

  16. Emergency Department Presentations following Tropical Cyclone Yasi.

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2012-09-04

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

  18. Ocean Barrier Layers’ Effect on Tropical Cyclone Intensification

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-09-04

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

  19. Tropical cyclones over NIO during La-Nina Modoki years

    Digital Repository Service at National Institute of Oceanography (India)

    Sumesh, K.G.; RameshKumar, M.R.

    Tropical cyclones over NIO (North Indian Ocean) are highly influenced by the El-Nino and La-Nina activities over the Pacific Ocean Influences of air-sea interaction processes like El-Nino Modoki and La-Nina Modoki on tropical cyclones are less...

  20. Emergency Department Presentations following Tropical Cyclone Yasi.

    Directory of Open Access Journals (Sweden)

    Peter Aitken

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

  1. Tropical Cyclone Structure and Intensity Change.

    Science.gov (United States)

    Nunez, Edwin

    This paper is concerned with two basic areas in the study of tropical cyclones: (a)structure and (b)genesis and intensity change. Utilizing the compositing approach, fourteen years (1961-1974) of northwest Atlantic rawinsonde soundings are analyzed to obtain the basic thermodynamic and wind fields of the hurricane. A comparison is undertaken of the basic structure of the composited west Atlantic hurricane and the west Pacific typhoon as reported by Frank (1977a, b). Similarities and differences are discussed. In order to investigate differences which lead to tropical cyclone genesis and intensification, eighteen Atlantic and Pacific data sets are also composited and divided into two groups: (a)deepening and (b)filling/steady systems. Deepening systems are found to have supergradient winds in the lower troposphere and less subgradient winds in the upper levels than filling/steady disturbances. The thermal wind equation indicates that an imbalance exists such that deepening systems have larger vertical tangential wind shear (WS) than baroclinicity. The opposite is true of filling systems. A genesis and intensification mechanism is proposed based on the adjustment of the baroclinicity to the imbalance in the vertical shear of the tangential wind. This mechanism agrees with the work of Silva Dias and Schubert (1979) and Schubert et al. (1980) which shows that in the tropics --where the Rossby radius of deformation is large--the temperature field adjusts to the wind field. It is suggested that the initial imbalance results from alterations of the disturbance's rotational part of the wind caused by the large-scale flow. Cumulus clouds and vertical mass recycling occurring in this favorable initial vertical shear are thought to maintain and increase the original imbalance. The system tries to reach a balanced state by increasing the baroclinicity (B) in order to balance the larger vertical wind shear (WS). Intensification is produced as the inner area of the disturbance

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

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

    2013-12-05

    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.

  4. More tropical cyclones in a cooler climate?

    Science.gov (United States)

    Sugi, Masato; Yoshida, Kohei; Murakami, Hiroyuki

    2015-08-01

    Recent review papers reported that many high-resolution global climate models consistently projected a reduction of global tropical cyclone (TC) frequency in a future warmer climate, although the mechanism of the reduction is not yet fully understood. Here we present a result of 4K-cooler climate experiment. The global TC frequency significantly increases in the 4K-cooler climate compared to the present climate. This is consistent with a significant decrease in TC frequency in the 4K-warmer climate. For the mechanism of TC frequency reduction in a warmer climate, upward mass flux hypothesis and saturation deficit hypothesis have been proposed. The result of the 4K-cooler climate experiment is consistent with these two hypotheses. One very interesting point is that the experiment has clearly shown that TC genesis is possible at sea surface temperature (SST) well below 26°C which has been considered as the lowest SST limit for TC genesis.

  5. Targeted ocean sampling guidance for tropical cyclones

    Science.gov (United States)

    Chen, Sue; Cummings, James A.; Schmidt, Jerome M.; Sanabia, Elizabeth R.; Jayne, Steven R.

    2017-05-01

    A 3-D variational ocean data assimilation adjoint approach is used to examine the impact of ocean observations on coupled tropical cyclone (TC) model forecast error for three recent hurricanes: Isaac (2012), Hilda (2015), and Matthew (2016). In addition, this methodology is applied to develop an innovative ocean observation targeting tool validated using TC model simulations that assimilate ocean temperature observed by Airborne eXpendable Bathy Thermographs and Air-Launched Autonomous Micro-Observer floats. Comparison between the simulated targeted and real observation data assimilation impacts reveals a positive maximum mean linear correlation of 0.53 at 400-500 m, which implies some skill in the targeting application. Targeted ocean observation regions from these three hurricanes, however, show that the largest positive impacts in reducing the TC model forecast errors are sensitive to the initial prestorm ocean conditions such as the location and magnitude of preexisting ocean eddies, storm-induced ocean cold wake, and model track errors.

  6. Climatology and Landfall of Tropical Cyclones in the South- West ...

    African Journals Online (AJOL)

    Keywords: Tropical cyclones, Indian Ocean, Mozambique Channel, global change, sea surface temperatures, ENSO, landfall. Abstract—The ... This should be particularly true for more remote cyclone regions such as the SWIO, .... global warming and increasing SSTs are addressed, for the accurate determination of areas of ...

  7. Sensitivity of tropical cyclone Jal simulations to physics ...

    Indian Academy of Sciences (India)

    ... to physics parameterizations is carried out with a view to determine the best set of physics options for prediction of cyclones originating in the north Indian Ocean. For this purpose, the tropical cyclone Jal has been simulated by the advanced (or state of science) mesoscale Weather Research and Forecasting (WRF) model ...

  8. The persistent signature of tropical cyclones in ambient seismic noise

    Science.gov (United States)

    Gualtieri, Lucia; Camargo, Suzana J.; Pascale, Salvatore; Pons, Flavio M. E.; Ekström, Göran

    2018-02-01

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  10. The persistent signature of tropical cyclones in ambient seismic noise

    KAUST Repository

    Gualtieri, Lucia

    2017-12-28

    The spectrum of ambient seismic noise shows strong signals associated with tropical cyclones, yet a detailed understanding of these signals and the relationship between them and the storms is currently lacking. Through the analysis of more than a decade of seismic data recorded at several stations located in and adjacent to the northwest Pacific Ocean, here we show that there is a persistent and frequency-dependent signature of tropical cyclones in ambient seismic noise that depends on characteristics of the storm and on the detailed location of the station relative to the storm. An adaptive statistical model shows that the spectral amplitude of ambient seismic noise, and notably of the short-period secondary microseisms, has a strong relationship with tropical cyclone intensity and can be employed to extract information on the tropical cyclones.

  11. Global climate change and tropical cyclones

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-11-01

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

  12. Archive Compiles New Resource for Global Tropical Cyclone Research

    Science.gov (United States)

    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.

  13. Contrasting tropical cyclone and non-tropical cyclone related rainfall drop size distribution at Darwin, Australia

    Science.gov (United States)

    Deo, Anil; Walsh, Kevin J. E.

    2016-11-01

    In this study the rainfall drop size distribution (DSD) during the passage of seven tropical cyclones (TCs) over Darwin is compared and contrasted with that associated with non-tropical cyclone (non-TC) events, using the impact disdrometer data at the Darwin Atmospheric Radiation and Measurement (ARM) site. The disparity of the DSD with respect to rainfall types (between TC and non-TC conditions) and distance from TC centre is also examined. It is shown that TC DSDs are statistically different from the non-TC DSDs, the former encompassing a larger concentration of small to moderate drop sizes. The TC mass-weighted mean diameter (Dm) is lower than the non-TC values at all rain rates and also for the different precipitation types (convective, transition and stratiform). The TC DSD varies with distance from the TC centre, as rainfall near the TC centre (< 60 km) comprises of relatively smaller drops which are strongly evident at small to moderate rain rates (< 30 mm h- 1). Such variations in the DSD have implications for the parameters used in the algorithm that converts radar reflectivity to rainfall rate in TCs, as well as for the analytical expressions used in describing the observed DSD employed in cloud modelling parameterizations.

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

    Science.gov (United States)

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

    2012-12-01

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

  15. Revisiting the Future Projections of Tropical Cyclones Intensity

    Science.gov (United States)

    Liu, H.; Foltz, G. R.

    2016-12-01

    The varying atmospheric and oceanic states impact the tropical cyclone intensity on both short-term weather time scales and long-term climate time scales. In a warming climate, the changes of environmental conditions of the atmosphere and ocean are not uniform and it is complicated to estimate the net influence on tropical cyclones. This study adopts the recently improved Dynamic Potential Intensity (DPI) which applies the depth averaged temperature and involves the subsurface salinity-induced stratification information. By using the Simple Ocean Data Assimilation reanalysis, and the IBTrACS (International Best Track Archive for Climate Stewardship) tropical cyclone best track data, a minimum DPI threshold is established for the intensification of TCs into category five hurricanes or typhoons in different regions of global tropical cyclones. The projected changes in accordance with the established minimum threshold under the CMIP5 RCP 4.5 and 8.5 scenarios are further analyzed using the ensemble DPI mean from CMIP5 models. The role of salinity is estimated. Results suggest that the depth averaged temperature which includes the effect of salinity stratification will continue to rise attributed to greenhouse gas emissions (GHG). However, the projected atmosphere condition in the future largely compensates for the influences of ocean temperature increases on the intensity of tropical cyclones.

  16. Infectious Diseases and Tropical Cyclones in Southeast China

    Directory of Open Access Journals (Sweden)

    Jietao Zheng

    2017-05-01

    Full Text Available Southeast China is frequently hit by tropical cyclones (TCs with significant economic and health burdens each year. However, there is a lack of understanding of what infectious diseases could be affected by tropical cyclones. This study aimed to examine the impacts of tropical cyclones on notifiable infectious diseases in southeast China. Disease data between 2005 and 2011 from four coastal provinces in southeast China, including Guangdong, Hainan, Zhejiang, and Fujian province, were collected. Numbers of cases of 14 infectious diseases were compared between risk periods and reference periods for each tropical cyclone. Risk ratios (RRs were calculated to estimate the risks. TCs were more likely to increase the risk of bacillary dysentery, paratyphoid fever, dengue fever and acute hemorrhagic conjunctivitis (ps < 0.05 than to decrease the risk, more likely to decrease the risk of measles, mumps, varicella and vivax malaria (ps < 0.05 than to increase the risk. In conclusion, TCs have mixed effects on the risk of infectious diseases. TCs are more likely to increase the risk of intestinal and contact transmitted infectious diseases than to decrease the risk, and more likely to decrease the risk of respiratory infectious diseases than to increase the risk. Findings of this study would assist in developing public health strategies and interventions for the reduction of the adverse health impacts from tropical cyclones.

  17. Infectious Diseases and Tropical Cyclones in Southeast China.

    Science.gov (United States)

    Zheng, Jietao; Han, Weixiao; Jiang, Baofa; Ma, Wei; Zhang, Ying

    2017-05-07

    Southeast China is frequently hit by tropical cyclones (TCs) with significant economic and health burdens each year. However, there is a lack of understanding of what infectious diseases could be affected by tropical cyclones. This study aimed to examine the impacts of tropical cyclones on notifiable infectious diseases in southeast China. Disease data between 2005 and 2011 from four coastal provinces in southeast China, including Guangdong, Hainan, Zhejiang, and Fujian province, were collected. Numbers of cases of 14 infectious diseases were compared between risk periods and reference periods for each tropical cyclone. Risk ratios (RR s ) were calculated to estimate the risks. TCs were more likely to increase the risk of bacillary dysentery, paratyphoid fever, dengue fever and acute hemorrhagic conjunctivitis ( ps risk, more likely to decrease the risk of measles, mumps, varicella and vivax malaria ( ps risk. In conclusion, TCs have mixed effects on the risk of infectious diseases. TCs are more likely to increase the risk of intestinal and contact transmitted infectious diseases than to decrease the risk, and more likely to decrease the risk of respiratory infectious diseases than to increase the risk. Findings of this study would assist in developing public health strategies and interventions for the reduction of the adverse health impacts from tropical cyclones.

  18. Thermodynamic Aspects of Tropical Cyclone Formation

    Science.gov (United States)

    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-β area near the pouch center is characterized by high saturation fraction, small difference in equivalent potential temperature (θe) 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 θe 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) θe difference between 950 mb and 700 mb (950 mb "minus" 700 hPa; units: K), and (c) χm in the numerical model simulation of Felix.

  19. NOAA JPSS Advanced Technology Microwave Sounder (ATMS)-based Tropical Cyclone (TC) Products from NDE

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The JPSS Microwave Sounder-based Tropical Cyclone (TC) Products provide estimates of tropical cyclone maximum wind speed, minimum sea level pressure, radii of 34,...

  20. Damage costs of climate change through intensification of tropical cyclone activities: An application of FUND

    NARCIS (Netherlands)

    Narita, D.; Anthoff, D.; Tol, R.S.J.

    2009-01-01

    Climate change may intensify tropical cyclone activities and amplify their negative economic effects. We simulated the direct economic impact of tropical cyclones enhanced by climate change with the integrated assessment model Climate Framework for Uncertainty, Negotiation and Distribution (FUND),

  1. TRMM TROPICAL CYCLONE PRECIPITATION FEATURE (TCPF) DATABASE - LEVEL 1 V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The TRMM Cyclone Precipitation Feature (TCPF) Database - Level 1 provides Tropical Rainfall Measuring Mission (TRMM)-based tropical cyclone data in a common...

  2. High resolution model projections of tropical cyclone landfall over southern Africa under enhanced anthropogenic forcing

    CSIR Research Space (South Africa)

    Malherbe, J

    2011-09-01

    Full Text Available Tropical cyclone landfall within the southwest Indian Ocean (SWIO) basin occurs on average about 3 times per year over Mozambique and Madagascar. Rainfall associated with tropical cyclones over the interior of southern Africa can also cause...

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

    Science.gov (United States)

    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.

  4. Revisiting the steering principal of tropical cyclone motion in a numerical experiment

    Science.gov (United States)

    Wu, Liguang; Chen, Xiaoyu

    2016-12-01

    The steering principle of tropical cyclone motion has been applied to tropical cyclone forecasting and research for nearly 100 years. Two fundamental questions remain unanswered. One is why the steering flow plays a dominant role in tropical cyclone motion, and the other is when tropical cyclone motion deviates considerably from the steering. A high-resolution numerical experiment was conducted with the tropical cyclone in a typical large-scale monsoon trough over the western North Pacific. The simulated tropical cyclone experiences two eyewall replacement processes. Based on the potential vorticity tendency (PVT) diagnostics, this study demonstrates that the conventional steering, which is calculated over a certain radius from the tropical cyclone center in the horizontal and a deep pressure layer in the vertical, plays a dominant role in tropical cyclone motion since the contributions from other processes are largely cancelled out due to the coherent structure of tropical cyclone circulation. Resulting from the asymmetric dynamics of the tropical cyclone inner core, the trochoidal motion around the mean tropical cyclone track cannot be accounted for by the conventional steering. The instantaneous tropical cyclone motion can considerably deviate from the conventional steering that approximately accounts for the combined effect of the contribution of the advection of the symmetric potential vorticity component by the asymmetric flow and the contribution from the advection of the wave-number-one potential vorticity component by the symmetric flow.

  5. On tropical cyclone frequency and the warm pool area

    Directory of Open Access Journals (Sweden)

    R. E. Benestad

    2009-04-01

    Full Text Available The proposition that the rate of tropical cyclogenesis increases with the size of the "warm pool" is tested by comparing the seasonal variation of the warm pool area with the seasonality of the number of tropical cyclones. An analysis based on empirical data from the Northern Hemisphere is presented, where the warm pool associated with tropical cyclone activity is defined as the area, A, enclosed by the 26.5°C SST isotherm. Similar analysis was applied to the temperature weighted area AT with similar results.

    An intriguing non-linear relationship of high statistical significance was found between the temperature weighted area in the North Atlantic and the North-West Pacific on the one hand and the number of cyclones, N, in the same ocean basin on the other, but this pattern was not found over the North Indian Ocean. A simple statistical model was developed, based on the historical relationship between N and A. The simple model was then validated against independent inter-annual variations in the seasonal cyclone counts in the North Atlantic, but the correlation was not statistically significant in the North-West Pacific. No correlation, however, was found between N and A in the North Indian Ocean.

    A non-linear relationship between the cyclone number and temperature weighted area may in some ocean basins explain both why there has not been any linear trend in the number of cyclones over time as well as the recent upturn in the number of Atlantic hurricanes. The results also suggest that the notion of the number of tropical cyclones being insensitive to the area A is a misconception.

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

    Science.gov (United States)

    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.

  7. Improvement of wind field hindcasts for tropical cyclones

    Directory of Open Access Journals (Sweden)

    Yi Pan

    2016-01-01

    Full Text Available This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the cross-calibrated multi-platform (CCMP reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

  8. Improvement of wind field hindcasts for tropical cyclones

    Directory of Open Access Journals (Sweden)

    Yi Pan

    2016-01-01

    Full Text Available This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the Cross-Calibrated Multi-Platform (CCMP reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

  9. A comparative study on the genesis of North Indian Ocean tropical cyclone Madi (2013) and Atlantic Ocean tropical cyclone Florence (2006)

    Science.gov (United States)

    Rajasree, V. P. M.; Kesarkar, Amit P.; Bhate, Jyoti N.; Singh, Vikas; Umakanth, U.; Varma, T. Harish

    2016-12-01

    A modeling study has been carried out to understand the similarities and differences in the genesis sequence of a Bay of Bengal tropical cyclone Madi (6-13 December 2013) and the Atlantic Ocean tropical cyclone Florence (3-12 September 2006) on the applicability of hypotheses of the marsupial theory of tropical cyclogenesis. We examined the role of the protective pouch and warm core formation during their genesis and intensification phases. We have chosen tropical cyclone Madi and tropical cyclone Florence for our study specifically due to both of these tropical cyclones originated from westward moving parent disturbance embedded in the intertropical convergence zone. Also, the genesis and intensification of tropical cyclone Florence were accompanied by a series of Saharan dust outbreaks. Our results indicated that the dry air intrusion was not a dominant detrimental factor for the genesis of tropical cyclone Madi and showed rapid intensification within the pouch region. However, in the case of the tropical cyclone Florence, the delay in the intensification as a category 1 tropical cyclone from its tropical depression stage was due to entrainment of the dry air into the core of cyclonic vortex up to 700 hPa from above. The results from this study showed that the wave pouch played a most significant role in the vorticity upscale cascade (First hypothesis) and moisture aggregation (Second hypothesis) in pregenesis period of both the tropical cyclones. It also prevented the lateral dry air intrusion (Second hypothesis) from the Saharan Air Layer during the genesis phase of tropical cyclone Florence.

  10. Impact of Vertical Wind Shear on Tropical Cyclone Rainfall

    Science.gov (United States)

    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.

  11. An Energetic Perspective on United States Tropical Cyclone Landfall Droughts

    Science.gov (United States)

    Truchelut, Ryan E.; Staehling, Erica M.

    2017-12-01

    The extremely active 2017 Atlantic hurricane season concluded an extended period of quiescent continental United States tropical cyclone landfall activity that began in 2006, commonly referred to as the landfall drought. We introduce an extended climatology of U.S. tropical cyclone activity based on accumulated cyclone energy (ACE) and use this data set to investigate variability and trends in landfall activity. The drought years between 2006 and 2016 recorded an average value of total annual ACE over the U.S. that was less than 60% of the 1900-2017 average. Scaling this landfall activity metric by basin-wide activity reveals a statistically significant downward trend since 1950, with the percentage of total Atlantic ACE expended over the continental U.S. at a series minimum during the recent drought period.

  12. Sensitivity of tropical cyclone characteristics to the radial distribution ...

    Indian Academy of Sciences (India)

    Sea Surface Temperature (SST) is crucial for the development and maintenance of a tropical cyclone. (TC) particularly below the storm core region. However, storm data below the core region is the most difficult to obtain, hence it is not clear yet that how sensitive the radial distribution of the SST impact the storm ...

  13. Evaluation of official tropical cyclone landfall forecast issued by India ...

    Indian Academy of Sciences (India)

    Evaluation of official tropical cyclone landfall forecast issued by India Meteorological Department ... Here an attempt is made to evaluate the TC landfall forecast issued by IMD during. 2003–2013 (11 years) by calculating the ..... products also helped forecasters to minimize the sub- jectivity and improve the TC forecasting ...

  14. Spatial and temporal distribution of North Atlantic tropical cyclones ...

    African Journals Online (AJOL)

    month of genesis and their lifecycles and to study the role of African Easterly Waves (AEWs) in North Atlantic cyclogenesis. Between 1980 and 2004, 269 tropical cyclones (TCs) were formed over the North Atlantic, 77% of which occurred during the August-October period and 95% of major hurricanes (TCs in which the ...

  15. Characteristics of surface wind structure of tropical cyclones over the ...

    Indian Academy of Sciences (India)

    Tropical cyclone (TC) wind field monitoring and forecast are important for mariners, ships on sea and modelling group for creation of synthetic vortex, and storm surge and coastal inundation forecasting. Among others, a multi-platform satellite surface wind analysis developed by Co-operative Institute for Research in the ...

  16. Tropical Cyclone Diurnal Cycle as Observed by TRMM

    Science.gov (United States)

    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

  17. Radio occultation bending angle anomalies during tropical cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, S.

    2011-01-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant...... signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye...

  18. Radio Occultation Bending Angle Anomalies During Tropical Cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant...... signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), we show that the bending angle anomaly of a GPS radio occultation signal is typically larger...

  19. The effect of tropical cyclones (typhoons) on emergency department visits.

    Science.gov (United States)

    Lin, Chien-Hao; Hou, Sen-Kuang; Shih, Frank Fuh-Yuan; Su, Syi

    2013-09-01

    Case reports have indicated that a tropical cyclone may increase Emergency Department (ED) visits significantly. To examine emergency health care demands across a series of tropical cyclones, and to build a predictive model to analyze a cyclone's potential effect. This was an observational non-concurrent prospective study performed in Taiwan. Twenty hospitals were included. The number of daily ED visits in each hospital was our primary end point, and data were retrieved from the database provided by the National Health Insurance Research Database. Our study examined the period from 2000 to 2008. A total of 22 tropical cyclones (typhoons) that had passed over eastern Taiwan and covered the area under study were included. Multiple linear regression time-series models were employed to estimate the effects of "days since typhoon landfall" and various characteristics of the typhoons on the end point of daily ED visits to each hospital. The final multiple linear regression time-series model showed that the number of daily ED visits increased in areas where a strong typhoon had landed directly, with the increase being evident during the first 2 days since landfall. Our model also indicated that the three most important variables to predict a change in the pattern of daily ED visits were intensity of typhoon, simultaneous heavy rain, and direct landfall. During tropical cyclones, emergency services were under increased demand in selected time periods and areas. Health care authorities should collect information to build local models to optimize their resources allocation in preparation. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  20. Coastal Hazard due to Tropical Cyclones in Mexico

    Science.gov (United States)

    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

  1. Characteristics of lightning activity in tropical cyclones developed over North Indian Ocean basin during 2010-2015

    Science.gov (United States)

    Ranalkar, M. R.; Pawar, S. D.; Pradeep Kumar, P.

    2017-05-01

    The characteristics of lightning activity in tropical cyclones (TCs) over North Indian Ocean (NIO) are presented using sample of 21 TCs developed during 2010-2015 using TRMM and World Wide Lightning Location Network (WWLLN) datasets along with information from annual reports of Regional Specialized Meteorological Center (RSMC), New Delhi. The microphysical features such as Polarization Corrected Brightness Temperature (PCT), attenuation corrected reflectivity factor, Ice Water Path (IWP) play a pivotal role in development of convective systems within TCs. The TCs exhibited systematic variation in lightning flashes per day within 300 km of estimated center during their life cycle irrespective of their severity and flash rate within 300 km of storm center. The lightning flashes ranged from 1 to 3500 flashes per day during pre-cyclone stage, 100 to 8000 flashes per day during cyclone stage and 0 to 4300 flashes per day during post-cyclone stage. The TCs produced maximum flash density in eyewall region (20-40 km) and outer rainband region (200-260 km). The WWLLN recorded 165,512 flashes within 300 km of TC centers during their life cycle. The maximum flashes occurred during cyclone stage followed by pre-cyclone and post-cyclone. The time variation of flash rate for all cyclones was episodic and primarily peaked during late night and early morning hours. The diurnal variation of lightning flashes during TCs due to variation in detection efficiency of WWLLN also controls temporal distribution of lightning activity. During rapid intensification, TCs produced profuse lightning flashes per hour. Episodic lightning flashes per hour occurred during weakening stage and prior to landfall. It is evident that outbreaks of lightning flashes prior to maximum intensity change as manifested in maximum sustained wind speed and fall in estimated central pressure (ECP) indicate potential predictive value of lightning activity for TC intensity change.

  2. High-frequency Oscillations in Eyewalls of Tropical Cyclones

    Science.gov (United States)

    Li, Weibiao; Chen, Shumin

    2017-04-01

    High-frequency oscillations, with periods of about 2 hours, are first identified by applying wavelet analysis to observed minutely wind speeds around the eye and eyewall of tropical cyclones (TCs). Analysis of a model simulation of Typhoon Hagupit (2008) shows that the oscillations also occur in the intensity of TC, vertical motion, convergence activity and air density around the eyewall. Sequences of oscillations in these variables follow a certain order. In a typical cycle, the drop of density in the planetary boundary layer (PBL) is followed by an increase in the inward radial wind; this enhanced frictional convergence causes increase in density, followed by a decrease in the inward radial wind. The increase in convergence in the PBL causes increase of updraft at the top of the PBL, followed by high vertical velocity at high altitude of 8-10 km, then the increase of the maximum wind speed, and vice versa. Key words: tropical cyclone, high-frequency oscillations, eyewall, intensity

  3. Statistical Tropical Cyclone Forecasting Techniques for the Southern Hemisphere.

    Science.gov (United States)

    1984-06-01

    TR 84-D7 We, STATISTICAL TROPICAL CYCLONE * FORECASTING TECHNIQUES FOR THE SOUTHERN HEMISPHERE C. Thomas 0. Keenan I, Bureau of Meteorology -c...NOTES : , *Author’s affiliation: Synoptic Research Section, Bureau of Meteorology , Melbourne, Australia. Research documented in TR 84-07 was performed...Techniques The Australian techniques were developed at the Bureau of Meteorology , Australia for use in the Australian area of fore- casting

  4. Idealized Tropical Cyclones in Atmospheric General Circulation Models

    Science.gov (United States)

    Reed, K. A.; Jablonowski, C.

    2008-12-01

    The paper discusses the design of idealized tropical cyclone experiments in Atmospheric General Circulation Models (GCMs). Our first goal is to suggest the evolution of an idealized tropical cyclone as a standard test case for atmospheric model developments that adds complexity to a dynamical-core and GCM test suite. In addition, we plan on using idealized cyclones as a test bed for hurricane-dust interactions in the Atlantic Ocean Basin and climate-hurricane sensitivity studies. A group of sensitivity tests will be presented using the National Center for Atmospheric Research's (NCAR) Community Atmosphere Model (CAM) 3.1. The tests are run in a so-called aqua-planet configuration that consists of an ocean-covered Earth with prescribed sea surface temperatures and radiative forcing. We utilize the CAM 3.1 Finite Volume dynamical core on a latitude-longitude grid at a half-degree horizontal resolution. The development of an idealized, initially weak warm-core vortex is investigated with varying initial parameters including vorticity, radius of maximum wind, latitude, and sea surface temperature. The evolution of the initial vortex is especially sensitive to the initial vorticity, and therefore the initial wind speed, and radius of maximum wind. This sensitivity is also related to the model resolution. Although model resolution has improved greatly over the last decade, improved resolution will still be needed to model tropical cyclones in global climate models. These sensitivity tests provide us with suitable initial parameter configurations to model tropical cyclogenesis in CAM 3.1 and other GCMs.

  5. Quantifying Environmental Control on Tropical Cyclone Intensity Change

    Science.gov (United States)

    2010-08-01

    is smaller and confined primarily to the Gulf of Mexico, Carribean Sea, and east of the Lesser Antilles. In the WPAC, SSTs vary significantly...environmental and climatology and persistence characteristics of tropical cyclones (TCs) undergoing different intensity changes in the western North Pacific...WPAC) and North Atlantic (ATL) ocean basins. Using the cumulative distribution functions of 24-h intensity changes from the 2003–08 best-track data, four

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

    Science.gov (United States)

    Wilson, Robert M.

    2007-01-01

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

  7. Lagrangian Coherent Structures in Tropical Cyclone Intensification

    Science.gov (United States)

    2011-09-21

    2010; Montgomery et al., 2010; Fang and Zhang, 2010; Levina and Montgomery,5 2010). From a mean-field viewpoint associated with an azimuthal average...is a complex problem in moist helical turbulence 5 ( Levina and Montgomery, 2010). To better understand the struc- tural aspects of the intensification... Levina , G. and Montgomery, M. T.: A first examination of the helical nature of tropical cycloge-25 nesis, Doklady Earth Sci., 434, Part I, 1285–1289, 2010

  8. Detection of centers of tropical cyclones using Communication, Ocean, and Meteorological Satellite data

    Science.gov (United States)

    Lee, Juhyun; Im, Jungho; Park, Seohui; Yoo, Cheolhee

    2017-04-01

    Tropical cyclones are one of major natural disasters, which results in huge damages to human and society. Analyzing behaviors and characteristics of tropical cyclones is essential for mitigating the damages by tropical cyclones. In particular, it is important to keep track of the centers of tropical cyclones. Cyclone center and track information (called Best Track) provided by Joint Typhoon Warning Center (JTWC) are widely used for the reference data of tropical cyclone centers. However, JTWC uses multiple resources including numerical modeling, geostationary satellite data, and in situ measurements to determine the best track in a subjective way and makes it available to the public 6 months later after an event occurred. Thus, the best track data cannot be operationally used to identify the centers of tropical cyclones in real time. In this study, we proposed an automated approach for identifying the centers of tropical cyclones using only Communication, Ocean, and Meteorological Satellite (COMS) Meteorological Imager (MI) sensor derived data. It contains 5 bands—VIS (0.67µm), SWIR (3.7µm), WV (6.7µm), IR1 (10.8µm), and IR2 (12.0µm). We used IR1 band images to extract brightness temperatures of cloud tops over Western North Pacific between 2011 and 2012. The Angle deviation between brightness temperature-based gradient direction in a moving window and the reference angle toward the center of the window was extracted. Then, a spatial analysis index called circular variance was adopted to identify the centers of tropical cyclones based on the angle deviation. Finally, the locations of the minimum circular variance indexes were identified as the centers of tropical cyclones. While the proposed method has comparable performance for detecting cyclone centers in case of organized cloud convections when compared with the best track data, it identified the cyclone centers distant ( 2 degrees) from the best track centers for unorganized convections.

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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.

  11. Retrograde waves in tropical cyclone inner-core

    Directory of Open Access Journals (Sweden)

    Chanh Kieu

    2016-10-01

    Full Text Available This study presents an extension of Kelvin's vortex wave model for the inner-core region of tropical cyclone-like vortices. By considering a more suitable approximation for tropical cyclones (TCs for which the horizontal scale of the TC inner-core is significantly larger than the TC vertical depth and taking into account the TC inherent baroclinicity, it is shown that there exists a retrograde wave mode in which the wave propagation is opposite to the mean tangential flow for the azimuthal wavenumber 1. While this result appears to be similar to that obtained in Kelvin's wave model, the retrograde mode in the TC-like vortices depends critically on the TC baroclinicity that Kelvin's model does not contain. Idealised simulations of a TC-like vortex using the full-physics Hurricane Weather Research and Forecasting (HWRF model indeed capture existence of the retrograde waves inside the vortex inner-core at the high intensity limit. Despite the brief existence of this retrograde mode, the emergence of retrograde waves in the HWRF simulations is of significance, because they may be related to subsequent wave growth and formation of mesovortices that are often observed inside the core region of intense TCs.

  12. Balanced thermal structure of an intensifying tropical cyclone

    Directory of Open Access Journals (Sweden)

    David J. Raymond

    2012-12-01

    Full Text Available This study tests the hypothesis that the formation of a virtual potential temperature dipole in a developing tropical cyclone is a balanced response to the growth of an associated mid-level vortex. The dipole is collocated with the vortex and consists of a warm anomaly in the upper troposphere and a cool anomaly in the lower troposphere. An axisymmetric approximation to the observed potential vorticity distribution is inverted subject to non-linear balance for two successive days during the formation of typhoon Nuri in 2008. Good agreement is found between the area-averaged actual and balanced virtual temperature dipoles in these two cases. Furthermore, a strong correlation exists between the degree of bottom-heaviness of convective mass flux profiles and the strength of the balanced virtual potential temperature dipole. Since the dipole is balanced, it cannot be an immediate artefact of the existing convection, but rather is an inherent feature of the developing cyclone. Cloud resolving numerical modelling suggests that the dipole temperature anomaly actually promotes more bottom-heavy convective mass flux profiles, as observed. Such profiles are associated with low-level mass and vorticity convergence via mass continuity and the circulation theorem, resulting in low-level spin-up. The present work thus supports the hypothesis that the low-level spin-up associated with tropical cyclogenesis is made possible by the thermodynamic environment created by a strong mid-level vortex.

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

    Science.gov (United States)

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

    2015-04-01

    floodplain reaches of Cambodia. Furthermore, it is shown that the proportion of flux generated from tropical cyclones increases downstream and dominates (~60%) the flux observed around the confluence of the 3S basin (the Se San, Sre Pok and Se Kong Rivers) which drains the Vietnamese highlands. This implies future changes in cyclone tracks may impact upon sediment delivery to the Mekong delta.

  14. Impacts of tropical cyclones and accompanying precipitation on infectious diarrhea in cyclone landing areas of Zhejiang Province, China.

    Science.gov (United States)

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

    2015-01-22

    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. 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). 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. 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.

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

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    Zhengyi Deng

    2015-01-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2011-01-01

    Complimenting modern records of tropical cyclone activity with longer historical and paleoclimatological records would increase our understanding of natural tropical cyclone variability on decadal to centennial time scales. Tropical cyclones produce large amounts of precipitation with significantly lower δ18O values than normal precipitation, and hence may be geochemically identifiable as negative δ18O anomalies in marine carbonate δ18O records. This study investigates the usefulness of coral skeletal δ18O as a means of reconstructing past tropical cyclone events. Isotopic modeling of rainfall mixing with seawater shows that detecting an isotopic signal from a tropical cyclone in a coral requires a salinity of ~ 33 psu at the time of coral growth, but this threshold is dependent on the isotopic composition of both fresh and saline end-members. A comparison between coral δ18O and historical records of tropical cyclone activity, river discharge, and precipitation from multiple sites in Puerto Rico shows that tropical cyclones are not distinguishable in the coral record from normal rainfall using this approach at these sites.

  17. Contributions of tropical waves to tropical cyclone genesis over the western North Pacific

    Science.gov (United States)

    Wu, Liang; Takahashi, Masaaki

    2017-09-01

    The present study investigates the relationship between the tropical waves and the tropical cyclone (TC) genesis over the western North Pacific (WNP) for the period 1979-2011. Five wave types are considered in this study. It is shown that the TC genesis is strongly related to enhanced low-level vorticity and convection of tropical waves and significant difference are detected in the TC modulation by dynamic and thermodynamic components of the waves. More TCs tend to form in regions of waves with overlapping cyclonic vorticity and active convection. About 83.2% of TCs form within active phase of tropical waves, mainly in a single wave and two coexisting waves. Each wave type-related genesis accounts for about 30% of all TC geneses except for the Kelvin waves that account for only 25.2% of TC geneses. The number of each wave type-related TC genesis consistently varies seasonally with peak in the TC season (July-November), which is attributed to a combined effect of active wave probability and intensity change. The interannual variation in the TC genesis is well reproduced by the tropical wave-related TC genesis, especially in the region east of 150°E. An eastward extension of the enhanced monsoon trough coincides with increased tropical wave activity by accelerated wave-mean flow interaction.

  18. Do tropical cyclones shape shorebird habitat patterns? Biogeoclimatology of snowy plovers in Florida.

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    Matteo Convertino

    Full Text Available 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.

  19. Do tropical cyclones shape shorebird habitat patterns? Biogeoclimatology of snowy plovers in Florida.

    Science.gov (United States)

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

    2011-01-12

    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. 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. 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.

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

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    K. J. Tory

    2013-02-01

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2006-01-01

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

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

    Science.gov (United States)

    Marler, Thomas E; Ferreras, Ulysses

    2014-01-01

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

  5. Leveraging LSTM for rapid intensifications prediction of tropical cyclones

    Science.gov (United States)

    Li, Y.; Yang, R.; Yang, C.; Yu, M.; Hu, F.; Jiang, Y.

    2017-10-01

    Tropical cyclones (TCs) usually cause severe damages and destructions. TC intensity forecasting helps people prepare for the extreme weather and could save lives and properties. Rapid Intensifications (RI) of TCs are the major error sources of TC intensity forecasting. A large number of factors, such as sea surface temperature and wind shear, affect the RI processes of TCs. Quite a lot of work have been done to identify the combination of conditions most favorable to RI. In this study, deep learning method is utilized to combine conditions for RI prediction of TCs. Experiments show that the long short-term memory (LSTM) network provides the ability to leverage past conditions to predict TC rapid intensifications.

  6. Impacts of hemispheric solar geoengineering on tropical cyclone frequency.

    Science.gov (United States)

    Jones, Anthony C; Haywood, James M; Dunstone, Nick; Emanuel, Kerry; Hawcroft, Matthew K; Hodges, Kevin I; Jones, Andy

    2017-11-14

    Solar geoengineering refers to a range of proposed methods for counteracting global warming by artificially reducing sunlight at Earth's surface. The most widely known solar geoengineering proposal is stratospheric aerosol injection (SAI), which has impacts analogous to those from volcanic eruptions. Observations following major volcanic eruptions indicate that aerosol enhancements confined to a single hemisphere effectively modulate North Atlantic tropical cyclone (TC) activity in the following years. Here we investigate the effects of both single-hemisphere and global SAI scenarios on North Atlantic TC activity using the HadGEM2-ES general circulation model and various TC identification methods. We show that a robust result from all of the methods is that SAI applied to the southern hemisphere would enhance TC frequency relative to a global SAI application, and vice versa for SAI in the northern hemisphere. Our results reemphasise concerns regarding regional geoengineering and should motivate policymakers to regulate large-scale unilateral geoengineering deployments.

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

    Science.gov (United States)

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

    2013-04-01

    Tropical cyclones are the most extreme weather phenomena which severely impact coastal communities and island nations. There is an ongoing research (i) on accurate analysis of observed trends in tropical cyclone occurrences, and (ii) how tropical cyclone frequency and intensity may change in the future as a result of climate change. Reliable historical records of cyclone activity are vital for this research. The Pacific Australia Climate Change Science and Adaptation Planning (PACCSAP) program is dedicated to help Pacific Island countries and Timor Leste gain a better understanding of how climate change will impact their regions. One of the key PACCSAP projects is focused on developing a tropical cyclone archive, climatology and seasonal prediction for the regions. As part of the project, historical tropical cyclone best track data have been examined and prepared to be subsequently displayed through the enhanced tropical cyclone data portal for the Southern Hemisphere and the Western Pacific Ocean. Data from the Regional Specialised Meteorological Centre (RSMC) Nadi, Fiji and Tropical Cyclone Warning Centres (TCWCs) in Brisbane, Darwin and Wellington for 1969-1970 to 2010-2011 tropical cyclone seasons have been carefully examined. Errors and inconsistencies which have been found during the quality control procedure have been corrected. To produce a consolidated data set for the South Pacific Ocean, best track data from these four centres have been used. Specifically, for 1969-1970 to 1994-1995 tropical cyclone seasons, data from TCWCs in Brisbane, Darwin and Wellington have been used. In 1995, RSMC Nadi, Fiji has been established with responsibilities for issuing tropical cyclone warnings and preparing best track data for the area south of the equator to 25°S, 160°E to 120°W. Consequently, data from RSMC Nadi have been used as a primary source for this area, starting from the 1995-1996 tropical cyclone season. These data have been combined with the data from

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

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

    2011-11-02

    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.

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

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    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. © 2014 John Wiley & Sons Ltd.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Braun, Scott A.

    2012-01-01

    The controversial role of the dry Saharan Air Layer (SAL) on tropical storm intensification in the Atlantic will be addressed. The SAL has been argued in previous studies to have potential positive influences on storm development, but most recent studies have argued for a strong suppressing influence on storm intensification as a result of dry air, high stability, increased vertical wind shear, and microphysical impacts of dust. Here, we focus on observations of Hurricane Helene (2006), which occurred during the NASA African Monsoon Multidisciplinary Activities (NAMMA) experiment. Satellite and airborne observations, combined with global meteorological analyses depict the initial environment of Helene as being dominated by the SAL, although with minimal evidence that the SAL air actually penetrated to the core of the disturbance. Over the next several days, the SAL air quickly moved westward and was gradually replaced by a very dry, dust-free layer associated with subsidence. Despite the wrapping of this very dry air around the storm, Helene intensified steadily to a Category 3 hurricane suggesting that the dry air was unable to significantly slow storm intensification. Several uncertainties remain about the role of the SAL in Helene (and in tropical cyclones in general). To better address these uncertainties, NASA will be conducting a three year airborne campaign called the Hurricane and Severe Storm Sentinel (HS3). The HS3 objectives are: To obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers (that help to isolate tropical disturbances from hostile environments). To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. The mission objectives will be achieved using

  12. A meridional dipole in premonsoon Bay of Bengal tropical cyclone activity induced by ENSO: TROPICAL CYCLONES, MONSOON AND ENSO

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    Balaguru, Karthik [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Seattle Washington USA; Leung, L. Ruby [Atmospheric Sciences and Global Change, Pacific Northwest National Laboratory, Richland Washington USA; Lu, Jian [Atmospheric Sciences and Global Change, Pacific Northwest National Laboratory, Richland Washington USA; Foltz, Gregory R. [Physical Oceanography Division, Atlantic Oceanographic and Meteorological Laboratory, Miami Florida USA

    2016-06-27

    Analysis of Bay of Bengal tropical cyclone (TC) track data for the month of May during 1980-2013 reveals a meridional dipole in TC intensification: TC intensification rates increased in the northern Bay and decreased in the southern Bay. The dipole was driven by an increase in low-level vorticity and atmospheric humidity in the northern Bay, making the environment more favorable for TC intensification, and enhanced vertical wind shear in the southern Bay, tending to reduce TC development. These environmental changes were associated with a strengthening of the monsoon circulation for the month of May, driven by a La Nin˜a-like shift in tropical Pacific SSTs andassociated tropical wave dynamics. Analysis of a suite of climate models fromthe CMIP5 archive for the 150-year historical period shows that most models correctly reproduce the link between ENSO and Bay of Bengal TC activity through the monsoon at interannual timescales. Under the RCP 8.5 scenario the same CMIP5 models produce an El Nin˜o like warming trend in the equatorial Pacific, tending to weaken the monsoon circulation. These results suggest

  13. Impacts of different grades of tropical cyclones on infectious diarrhea in Guangdong, 2005-2011.

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    Ruihua Kang

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

  14. Impacts of different grades of tropical cyclones on infectious diarrhea in Guangdong, 2005-2011.

    Science.gov (United States)

    Kang, Ruihua; Xun, Huanmiao; Zhang, Ying; Wang, Wei; Wang, Xin; Jiang, Baofa; Ma, Wei

    2015-01-01

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

  15. IMPACT ASSESSMENT OF TROPICAL CYCLONE HUD HUD ON COASTAL REGION OF VISAKHAPATNAM, ANDHRA PRADESH, INDIA

    Directory of Open Access Journals (Sweden)

    G. Vivek

    2015-10-01

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

  16. Observing and Modelling the HighWater Level from Satellite Radar Altimetry During Tropical Cyclones

    DEFF Research Database (Denmark)

    Deng, Xiaoli; Gharineiat, Zahra; Andersen, Ole Baltazar

    2016-01-01

    This paper investigates the capability of observing tropical cyclones using satellite radar altimetry. Two representative cyclones Yasi (February 2011) and Larry (March 2006) in the northeast Australian coastal area are selected based also on available tide gauge sea level measurements. It is sho...

  17. NOAA/National Hurricane Center Tropical Cyclone Forecasts WMS/WFS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Prototype Web Map Service and Web Feature Service containing NOAA National Hurricane Center tropical cyclone forecast information for Atlantic and Pacific basins....

  18. Strongest Tropical cyclones: 1980-2009: A 30-year collage of Hurricane Satellite (HURSAT) data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Strongest Tropical Cyclones: 1980-2009 poster - a 30-year collage of Hurricane Satellite (HURSAT) data. This poster depicts a series of 5 degree grids where within...

  19. A Review of Parametric Descriptions of Tropical Cyclone Wind-Wave Generation

    Directory of Open Access Journals (Sweden)

    Ian R. Young

    2017-10-01

    Full Text Available More than three decades of observations of tropical cyclone wind and wave fields have resulted in a detailed understanding of wave-growth dynamics, although details of the physics are still lacking. These observations are presented in a consistent manner, which provides the basis to be able to characterize the full wave spectrum in a parametric form throughout tropical cyclones. The data clearly shows that an extended fetch model can be used to represent the maximum significant wave height in such storms. The shape stabilizing influence of nonlinear interactions means that the spectral shape is remarkably similar to fetch-limited cases. As such, the tropical cyclone spectrum can also be described by using well-known parametric models. A detailed process is described to parameterize the wave spectrum at any point in a tropical cyclone.

  20. Historical North Atlantic Tropical Cyclone Tracks, 1851-2004 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This Historical North Atlantic Tropical Cyclone Tracks file contains the six-hourly (0000, 0600, 1200, 1800 UTC) center locations and intensities for all northern...

  1. Historical Eastern North Pacific Tropical Cyclone Tracks, 1949-2004 - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This Historical Eastern North Pacific Tropical Cyclone Tracks file contains the six-hourly (0000, 0600, 1200, 1800 UTC) center locations and intensities for all...

  2. nowCOAST's Map Service for NOAA Tropical Cyclone Track and Intensity Forecasts (Time Enabled)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Map Information: This nowCOAST time-enabled map service provides maps depicting the latest official NWS tropical cyclone forecast tracks and watches and warnings for...

  3. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T; Augustus, Ellsworth H; Colonnese, Christopher P

    2003-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  4. Predicting Tropical Cyclone Destructive Potential by Integrated Kinetic Energy According to the Powell/Reinhold Scale

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method of predicting the destructive capacity of a tropical cyclone based on a new Wind Destructive Potential (WDP) and Storm Surge Destructive Potential (SDP)...

  5. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2005-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  6. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2004-01-01

    The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

  7. Spatial Distributions of Tropical Cyclone Tornadoes by Intensity and Size Characteristics

    Directory of Open Access Journals (Sweden)

    Todd W. Moore

    2017-08-01

    Full Text Available Tropical cyclones that make landfall often spawn tornadoes. Previous studies have shown that these tornadoes are not uniformly distributed in the United States or in the tropical cyclone environment. They show that tornadoes tend to occur relatively close to the coastline and that they tend to cluster to the east-of-center in the tropical cyclone environment, particularly in the northeast and east-of-center quadrants. This study contributes to these studies by analyzing the spatial distributions of tropical cyclone tornadoes by intensity, path length, path width, and the damage potential index. The analyses confirm that most tornadoes occur relatively close to the coastline, but show that stronger tornadoes with larger paths are disproportionately common farther inland. They also confirm that the highest amount of activity is located within the northeast and east-of-center quadrants and show that the most potentially damaging tornadoes cluster in a sub region near the intersection of these two quadrants.

  8. Physical understanding of the tropical cyclone wind-pressure relationship.

    Science.gov (United States)

    Chavas, Daniel R; Reed, Kevin A; Knaff, John A

    2017-11-08

    The relationship between the two common measures of tropical cyclone intensity, the central pressure deficit and the peak near-surface wind speed, is a long-standing problem in tropical meteorology that has been approximated empirically yet lacks physical understanding. Here we provide theoretical grounding for this relationship. We first demonstrate that the central pressure deficit is highly predictable from the low-level wind field via gradient wind balance. We then show that this relationship reduces to a dependence on two velocity scales: the maximum azimuthal-mean azimuthal wind speed and half the product of the Coriolis parameter and outer storm size. This simple theory is found to hold across a hierarchy of models spanning reduced-complexity and Earth-like global simulations and observations. Thus, the central pressure deficit is an intensity measure that combines maximum wind speed, storm size, and background rotation rate. This work has significant implications for both fundamental understanding and risk analysis, including why the central pressure better explains historical economic damages than does maximum wind speed.

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

    OpenAIRE

    Fedorov, Alexey V.; Brierley, Christopher M.; Emanuel, Kerry Andrew

    2009-01-01

    Tropical cyclones (also known as hurricanes and typhoons) are now believed to be an important component of the Earth’s climate system1, 2, 3. In particular, by vigorously mixing the upper ocean, they can affect the ocean’s heat uptake, poleward heat transport, and hence global temperatures. Changes in the distribution and frequency of tropical cyclones could therefore become an important element of the climate response to global warming. A potential analogue to modern greenhouse conditions, t...

  10. Epidemiology of injuries due to tropical cyclones in Hong Kong: a retrospective observational study.

    Science.gov (United States)

    Rotheray, K R; Aitken, P; Goggins, W B; Rainer, T H; Graham, C A

    2012-12-01

    Tropical cyclones are huge circulating masses of wind which form over tropical and sub-tropical waters. They affect an average of 78 million people each year. Hong Kong is a large urban centre with a population of just over 7 million which is frequently affected by tropical cyclones. We aimed to describe the numbers and types of injuries due to tropical cyclones in Hong Kong, as well as their relation to tropical cyclone characteristics. The records of all patients presenting to Hong Kong's public hospital emergency departments from 1st January 2004 to 31st December 2009 with tropical cyclone related injuries were reviewed and information regarding patient and injury characteristics was collected. Meteorological records for the relevant periods were examined and data on wind speed, rainfall and timing of landfall and warning signals was recorded and compared with the timing of tropical cyclone related injuries. A total of 460 tropical cyclone related injuries and one fatality across 15 emergency departments were identified during the study period. The mean age of those injured was 48 years and 48% were female. 25.4% of injuries were work related. The head (33.5%) and upper limb (32.5%) were the most commonly injured regions, with contusions (48.6%) and lacerations (30.2%) being the most common injury types. Falls (42.6%) were the most common mechanism of injury, followed by being hit by a falling or flying object (22.0%). In univariable analysis the relative risk of injury increased with mean hourly wind speed and hourly maximum gust. Multivariable analysis, however, showed that relative risk of injury increased with maximum gust but not average wind speed, with relative risk of injury rising sharply above maximum gusts of greater than 20 m/s. Moderate wind speed with high gust (rather than high average and high gust) appears to be the most risky situation for injuries. Relative risk of injury was not associated with rainfall. The majority of injuries (56

  11. Persistent northward North Atlantic tropical cyclone track migration over the past five centuries.

    Science.gov (United States)

    Baldini, Lisa M; Baldini, James U L; McElwaine, Jim N; Frappier, Amy Benoit; Asmerom, Yemane; Liu, Kam-Biu; Prufer, Keith M; Ridley, Harriet E; Polyak, Victor; Kennett, Douglas J; Macpherson, Colin G; Aquino, Valorie V; Awe, Jaime; Breitenbach, Sebastian F M

    2016-11-23

    Accurately predicting future tropical cyclone risk requires understanding the fundamental controls on tropical cyclone dynamics. Here we present an annually-resolved 450-year reconstruction of western Caribbean tropical cyclone activity developed using a new coupled carbon and oxygen isotope ratio technique in an exceptionally well-dated stalagmite from Belize. Western Caribbean tropical cyclone activity peaked at 1650 A.D., coincident with maximum Little Ice Age cooling, and decreased gradually until the end of the record in 1983. Considered with other reconstructions, the new record suggests that the mean track of Cape Verde tropical cyclones shifted gradually north-eastward from the western Caribbean toward the North American east coast over the last 450 years. Since ~1870 A.D., these shifts were largely driven by anthropogenic greenhouse gas and sulphate aerosol emissions. Our results strongly suggest that future emission scenarios will result in more frequent tropical cyclone impacts on the financial and population centres of the northeastern United States.

  12. Temporal clustering of tropical cyclones on the Great Barrier Reef and its ecological importance

    Science.gov (United States)

    Wolff, Nicholas H.; Wong, Aaron; Vitolo, Renato; Stolberg, Kristin; Anthony, Kenneth R. N.; Mumby, Peter J.

    2016-06-01

    Tropical cyclones have been a major cause of reef coral decline during recent decades, including on the Great Barrier Reef (GBR). While cyclones are a natural element of the disturbance regime of coral reefs, the role of temporal clustering has previously been overlooked. Here, we examine the consequences of different types of cyclone temporal distributions (clustered, stochastic or regular) on reef ecosystems. We subdivided the GBR into 14 adjoining regions, each spanning roughly 300 km, and quantified both the rate and clustering of cyclones using dispersion statistics. To interpret the consequences of such cyclone variability for coral reef health, we used a model of observed coral population dynamics. Results showed that clustering occurs on the margins of the cyclone belt, being strongest in the southern reefs and the far northern GBR, which also has the lowest cyclone rate. In the central GBR, where rates were greatest, cyclones had a relatively regular temporal pattern. Modelled dynamics of the dominant coral genus, Acropora, suggest that the long-term average cover might be more than 13 % greater (in absolute cover units) under a clustered cyclone regime compared to stochastic or regular regimes. Thus, not only does cyclone clustering vary significantly along the GBR but such clustering is predicted to have a marked, and management-relevant, impact on the status of coral populations. Additionally, we use our regional clustering and rate results to sample from a library of over 7000 synthetic cyclone tracks for the GBR. This allowed us to provide robust reef-scale maps of annual cyclone frequency and cyclone impacts on Acropora. We conclude that assessments of coral reef vulnerability need to account for both spatial and temporal cyclone distributions.

  13. Tropical cyclone fullness: A new concept for interpreting storm intensity

    Science.gov (United States)

    Guo, Xi; Tan, Zhe-Min

    2017-05-01

    Intensity and size are two crucial factors in determining the destructiveness of a tropical cyclone (TC), but little is known about the relationship between them because of a lack of observations. TC fullness, a new concept, is proposed to quantitatively measure the storm wind structure, which is defined as the ratio of the extent of the outer-core wind skirt to the outer-core size of the TC. TC intensity is more strongly correlated with fullness than with other measures comprising just a single size parameter. A scale is introduced to classify TCs into four categories based on TC fullness (FS1 to FS4). Regardless of the specific inner-core and outer-core size, the FS4 fullness structure is necessary for an intense TC's development, while category FS1 and FS2 TCs are generally weak. Most major TCs achieve FS4 fullness structure earlier and more frequently than nonmajor TCs. Rapidly increasing fullness favors the intensification of TC.Plain Language SummaryTropical cyclone (TC) disasters caused tremendous property loss and casualties all over the world every year, while the knowledge on what essentially determines TC intensity is far beyond enough. Should a large TC ought to be intense and disastrous? And is a small TC doomed to be weak? It confused us when some dapper small TCs struck us with their fierce wind and torrential rain, while other large TCs that finally turned out to be a false alarm tricked us with their puffiness body. The underlying factor that truly controls TC intensity has been grasped here. We unveil the mysteries between TC intensity and size by raising a new concept: TC fullness. Either small or large TC can be intense; it depends on the fullness. TCs should possess FS4 fullness structure (high fullness) as long as they are intense; on the other hand, TCs with low fullness are weak in majority. In addition, rapidly increasing fullness is beneficial for the intensification of TC. The concept of TC fullness may provide a new path in the

  14. A 320-year AMM+SOI Index Reconstruction from Historical Atlantic Tropical Cyclone Records

    Science.gov (United States)

    Chenoweth, M.; Divine, D.

    2010-12-01

    Trends in the frequency of North Atlantic tropical cyclones, including major hurricanes, are dominated by those originating in the deep tropics. In addition, these tropical cyclones are stronger when making landfall and their total power dissipation is higher than storms forming elsewhere in the Atlantic basin. Both the Atlantic Meridional Mode (AMM) and El Nino-Southern Oscillation (ENSO) are the leading modes of coupled air-sea interaction in the Atlantic and Pacific, respectively, and have well-established relationships with Atlantic hurricane variability. Here we use a 320-year record of tropical cyclone activity in the Lesser Antilles region of the North Atlantic from historical manuscript and newspaper records to reconstruct a normalized seasonal (July-October) index combining the Southern Oscillation Index (SOI) and AMM employing both the modern analog technique and back-propagation artificial neural networks. Our results indicate that the AMM+SOI index since 1690 shows no long-term trend but is dominated by both short-term (<10 years) and long-term (quasi-decadal to bi-decadal) variations. The decadal-scale variation is consistent with both instrumental and proxy records elsewhere from the global tropics. Distinct periods of high and low index values, corresponding to high and low tropical cyclone frequency, are regularly-appearing features in the record and provides further evidence that natural decadal -scale variability in Atlantic tropical cyclone frequency must be accounted for when determining trends in records and attribution of climate change.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2010-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-28

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

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

    Science.gov (United States)

    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. Multiple-Scale Interactions Affecting Tropical Cyclone Track Changes

    Directory of Open Access Journals (Sweden)

    Zhexian Luo

    2011-01-01

    Full Text Available Tropical Cyclone (TC track changes associated with Rossby wave energy dispersion are simulated in a shallow water primitive equation model with an initial field where a TC is located south of a subtropical high. An anticyclone east of the TC appears because of Rossby wave energy dispersion. The connection of the anticyclone with the subtropical high leads to a poleward TC track deflection. The TC eventually moves across the axis of the subtropical ridge. The formation of the track may be attributed to the nonlinear interaction between the subtropical high and the TC. This work validates the conceptual model proposed by previous observational research. The scenario of the nonlinear interaction between the TC and the subtropical high may also be modified through the influence of mesoscale vortices. The main modifications are (1 the anticyclone induced by energy dispersion of the TC weakens, (2 the connection between the anticyclone and the subtropical high is delayed, and (3 the TC shifts more westward and does not move across the ridge axis. We propose that some of the mesoscale vortices are axisymmetrized by the TC and results in an increase in TC size which modifies the properties of the energy dispersion. The phase and group speeds decrease and produce a simulated track deflection to the left compared to the simulation without mesoscale vortices. Our numerical results demonstrate that multiple scale nonlinear interactions have an essential role in influencing TC track changes.

  20. Forecasting tropical cyclone recurvature with upper tropospheric winds

    Science.gov (United States)

    Gentry, R. C.

    1983-01-01

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

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

    Science.gov (United States)

    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.

  2. Characterization of tropical cyclones in the South Indian Ocean by using GNSS observations

    Science.gov (United States)

    Nogherotto, Rita; Biondi, Riccardo; Leclair de Bellevue, Jimmy; Brenot, Hugues

    2017-04-01

    Tropical cyclones represent the most important weather system involving La Reunion Island and an accurate prediction of their track and intensity is crucial to reduce the damages caused by their strong precipitation and winds. Atmospheric water vapor is the main driver in the development of the cyclones and continuous observations of precipitable water (PW) from GNSS constitute a relevant tool in studying its temporal and spatial distribution. Because of the high temporal resolution of their observations, they allow the resolution of high-frequency (e.g. diurnal) variations and they can be used to study, monitor and predict weather extreme events such as the tropical cyclones. In this work we apply GNSS technique to measure ZTD and to obtain PW over the Southern Indian Ocean for the entire observational available period (2006-2016). We present the response of PW due to the passage of tropical cyclones. Using Radio Occultation profiles, we retrieve the cloud top altitude to find the relationship with storm intensity and PW variation. In addition we show the monitoring of the water vapor contents in direction of GNSS satellites and preliminary results about the 3D field of water vapor density over Reunion Island using tomography for Bejisa cyclone. This tropical cyclone affected Reunion Island and Mauritius in the late December 2013 and early January 2014 with strong consequences both on the population and on energy supplies.

  3. Assessing Impacts of Global Warming on Tropical Cyclone Tracks

    Science.gov (United States)

    Wu, Li-Guang; Wang, Bin

    2003-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Nigam, Sumant [University of Maryland, Department of Atmospheric and Oceanic Science, 3419 Computer and Space Science Building, College Park, MD (United States); Guan, Bin [University of Maryland, Department of Atmospheric and Oceanic Science, 3419 Computer and Space Science Building, College Park, MD (United States); California Institute of Technology, Water and Carbon Cycle Group, Jet Propulsion Laboratory, Pasadena, CA (United States)

    2011-06-15

    The twentieth century record of the annual count of Atlantic tropical cyclones (TCs) is analyzed to develop consistent estimates of its natural variability and secular change components. The analysis scheme permits development of multidecadal trends from natural variability alone, reducing aliasing of the variability and change components. The scheme is rooted in recurrent variability modes of the influential SST field and cognizant of Pacific-Atlantic links. The origin of increased cyclone counts in the early 1930s, suppressed counts in 1950-1960s, and the recent increase (since 1990s) is investigated using the count data set developed by Landsea et al. (J Clim 23: 2508-2519, 2010). We show that annual TC counts can be more closely reconstructed from Pacific and Atlantic SSTs than SST of the main development region (MDR) of Atlantic TCs; the former accounting for {proportional_to}60% of the decadal count variance as opposed to {proportional_to}30% for MDR SST. Atlantic Multidecadal Oscillation (AMO) dominates the reconstruction, accounting for {proportional_to}55% of the natural decadal count variance, followed by the ENSO Non-Canonical and Pan-Pacific decadal variability contributions. We argue for an expansive view of the domain of influential SSTs - extending much beyond the MDR. The additional accounting of count variance by SSTs outside the MDR suggests a role for remotely-forced influences over the tropical Atlantic: the Pan-Pacific decadal mode is linked with decreased westerly wind shear (200-850 hPa) in its warm phase, much as the AMO impact itself. Non-canonical ENSO variability, in contrast, exerts little influence on decadal timescales. Interestingly, the secular but non-uniform warming of the oceans is linked with increased westerly shear, leading to off-setting dynamical and thermodynamical impacts on TC activity. The early-1930s increase in smoothed counts can be partially ({proportional_to}50%) reconstructed from SST natural variability. The 1950

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

    Science.gov (United States)

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

    2012-01-01

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

  6. Impact of tropical cyclone Matmo on mixed zone of the Yellow and Bohai seas

    Science.gov (United States)

    Guo, Jie; Ji, Diansheng; Hou, Chawei; Guo, Kai; Ji, Ling

    2017-12-01

    The Bohai Sea is a low-lying semi-enclosed sea area that is linked to the Yellow Sea via the Bohai straits (mixed zone). Its off shore seabed is shallow, which makes it vulnerable to serious marine meteorological disasters associated with the northward passage of Pacifi c tropical cyclones. Analyses on data of remote sensing and buoy of the mixed zone of the Yellow and Bohai seas indicate that all the wind speed, signifi cant wave height, and salinity (SAL) increased, sea surface temperature decreased, and wind energy density changed considerably during the passage of tropical cyclone Matmo on July 25, 2014. It was found that the SAL inversion layer in the mixed zone of the Yellow and Bohai Seas was caused by the tropical cyclone. Furthermore, it was found that the tropical cyclone transported the northern Yellow Sea cold water mass (NYSCWM) into the mixed zone of the Yellow and Bohai Seas. The NYSCWM has direct infl uence on both the aquaculture and the ecological environment of the region. Therefore, further research is needed to establish the mechanism behind the formation of the SAL inversion layer in the mixed zone, and to determine the infl uence of tropical cyclones on the NYSCWM.

  7. Using Proxy Records to Document Gulf of Mexico Tropical Cyclones from 1820-1915.

    Science.gov (United States)

    Pino, Jordan V; Rohli, Robert V; DeLong, Kristine L; Harley, Grant L; Trepanier, Jill C

    2016-01-01

    Observations of pre-1950 tropical cyclones are sparse due to observational limitations; therefore, the hurricane database HURDAT2 (1851-present) maintained by the National Oceanic and Atmospheric Administration may be incomplete. Here we provide additional documentation for HURDAT2 from historical United States Army fort records (1820-1915) and other archived documents for 28 landfalling tropical cyclones, 20 of which are included in HURDAT2, along the northern Gulf of Mexico coast. One event that occurred in May 1863 is not currently documented in the HURDAT2 database but has been noted in other studies. We identify seven tropical cyclones that occurred before 1851, three of which are potential tropical cyclones. We corroborate the pre-HURDAT2 storms with a tree-ring reconstruction of hurricane impacts from the Florida Keys (1707-2009). Using this information, we suggest landfall locations for the July 1822 hurricane just west of Mobile, Alabama and 1831 hurricane near Last Island, Louisiana on 18 August. Furthermore, we model the probable track of the August 1831 hurricane using the weighted average distance grid method that incorporates historical tropical cyclone tracks to supplement report locations.

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

    Science.gov (United States)

    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.

  9. Tropical Cyclones, Derelict Traps, and the Future of the Florida Keys Commercial Spiny Lobster Fishery

    Science.gov (United States)

    Uhrin, A. V.

    2016-02-01

    Derelict spiny lobster (Panulirus argus) traps may move hundreds of meters during high wind events, resulting in tissue abrasion, breakage, and often complete removal of critical seagrass, sponge, and coral habitat. The legacy of commercial trap debris in the Florida Keys (USA) combined with possible increased inputs of debris resulting from a future rise in storm intensity presents an immediate challenge for fisheries management and the sustainability of this fishery where social and ecological vulnerabilities to disturbance are intrinsically linked. Here, predictions of trap loss in relation to wind speed under three scenarios of future tropical cyclone intensification were evaluated across four levels of fishery effort. Across all tropical cyclone intensity scenarios, Excessive effort produced the greatest number of lost traps, followed in decreasing order by Existing, Expected, and Optimal efforts. Under a Business-as-Usual scenario (BAU) of tropical cyclone activity, converting from Existing effort to Optimal effort reduced trap loss by over 60%. The scenarios suggest that were Existing fishery effort to be maintained in the coming decades, tropical cyclone-related trap loss could exceed 4.6-million depending upon the rate of storm intensification. Existing trap retrieval programs cannot remove trap debris equal to the rate it is currently accumulating. The net increase in derelict traps will only be exacerbated under an uncertain future of tropical cyclone intensification. This study also underscores the value of scenarios for exploring these issues, particularly evaluation of fisher responses to change.

  10. Using Proxy Records to Document Gulf of Mexico Tropical Cyclones from 1820-1915

    Science.gov (United States)

    Rohli, Robert V.; DeLong, Kristine L.; Harley, Grant L.; Trepanier, Jill C.

    2016-01-01

    Observations of pre-1950 tropical cyclones are sparse due to observational limitations; therefore, the hurricane database HURDAT2 (1851–present) maintained by the National Oceanic and Atmospheric Administration may be incomplete. Here we provide additional documentation for HURDAT2 from historical United States Army fort records (1820–1915) and other archived documents for 28 landfalling tropical cyclones, 20 of which are included in HURDAT2, along the northern Gulf of Mexico coast. One event that occurred in May 1863 is not currently documented in the HURDAT2 database but has been noted in other studies. We identify seven tropical cyclones that occurred before 1851, three of which are potential tropical cyclones. We corroborate the pre-HURDAT2 storms with a tree-ring reconstruction of hurricane impacts from the Florida Keys (1707–2009). Using this information, we suggest landfall locations for the July 1822 hurricane just west of Mobile, Alabama and 1831 hurricane near Last Island, Louisiana on 18 August. Furthermore, we model the probable track of the August 1831 hurricane using the weighted average distance grid method that incorporates historical tropical cyclone tracks to supplement report locations. PMID:27898726

  11. Impact of horizontal resolution on prediction of tropical cyclones over ...

    Indian Academy of Sciences (India)

    Two cyclones, which formed over the Bay of Bengal during the years 1995 and 1997, are simulated using a regional weather prediction model with two horizontal resolutions of 165km and 55 km. The model is found to perform reasonably well towards simulation of the storms. The structure, intensity and track of the cyclones ...

  12. Tropical cyclones over the North Indian Ocean: experiments with the high-resolution global icosahedral grid point model GME

    Science.gov (United States)

    Kumkar, Yogesh V.; Sen, P. N.; Chaudhari, Hemankumar S.; Oh, Jai-Ho

    2018-02-01

    In this paper, an attempt has been made to conduct a numerical experiment with the high-resolution global model GME to predict the tropical storms in the North Indian Ocean during the year 2007. Numerical integrations using the icosahedral hexagonal grid point global model GME were performed to study the evolution of tropical cyclones, viz., Akash, Gonu, Yemyin and Sidr over North Indian Ocean during 2007. It has been seen that the GME model forecast underestimates cyclone's intensity, but the model can capture the evolution of cyclone's intensity especially its weakening during landfall, which is primarily due to the cutoff of the water vapor supply in the boundary layer as cyclones approach the coastal region. A series of numerical simulation of tropical cyclones have been performed with GME to examine model capability in prediction of intensity and track of the cyclones. The model performance is evaluated by calculating the root mean square errors as cyclone track errors.

  13. A climatological model of North Indian Ocean tropical cyclone genesis, tracks and landfall

    Science.gov (United States)

    Wahiduzzaman, Mohammad; Oliver, Eric C. J.; Wotherspoon, Simon J.; Holbrook, Neil J.

    2017-10-01

    Extensive damage and loss of life can be caused by tropical cyclones (TCs) that make landfall. Modelling of TC landfall probability is beneficial to insurance/re-insurance companies, decision makers, government policy and planning, and residents in coastal areas. In this study, we develop a climatological model of tropical cyclone genesis, tracks and landfall for North Indian Ocean (NIO) rim countries based on kernel density estimation, a generalised additive model (GAM) including an Euler integration step, and landfall detection using a country mask approach. Using a 35-year record (1979-2013) of tropical cyclone track observations from the Joint Typhoon Warning Centre (part of the International Best Track Archive Climate Stewardship Version 6), the GAM is fitted to the observed cyclone track velocities as a smooth function of location in each season. The distribution of cyclone genesis points is approximated by kernel density estimation. The model simulated TCs are randomly selected from the fitted kernel (TC genesis), and the cyclone paths (TC tracks), represented by the GAM together with the application of stochastic innovations at each step, are simulated to generate a suite of NIO rim landfall statistics. Three hindcast validation methods are applied to evaluate the integrity of the model. First, leave-one-out cross validation is applied whereby the country of landfall is determined by the majority vote (considering the location by only highest percentage of landfall) from the simulated tracks. Second, the probability distribution of simulated landfall is evaluated against the observed landfall. Third, the distances between the point of observed landfall and simulated landfall are compared and quantified. Overall, the model shows very good cross-validated hindcast skill of modelled landfalling cyclones against observations in each of the NIO tropical cyclone seasons and for most NIO rim countries, with only a relatively small difference in the percentage of

  14. An Evaluation of 700 mb Aircraft Reconnaissance Data for Selected Northwest Pacific Tropical Cyclones.

    Science.gov (United States)

    1983-09-01

    cyclones Tropical cyclone intensity Typhoons Euvln oeta eprtr Hurricanes Eqivat poticentilr epeatr Aircraft reconnaissance Mossticerg ILANNtIACT ?CWM...except far TY Viola . 62 Fi;ure 13. Similar to Fig. 11, except for ST Kim . 62 Figure 14. Similar to Fig. 11, except far ST Irma . . . 63 Figure 15...for super typhoon Irma . .............. 77 Figure 24. Similar to Fig. 20, except for typhoonklice.. . . . . . . .. 78 Figure 25. Similar to Fig. 20

  15. Attribution of Annual Maximum Sea Levels to Tropical Cyclones

    Science.gov (United States)

    Khouakhi, A.; Villarini, G.

    2015-12-01

    Tropical cyclones (TCs) can cause catastrophic storm surges with major social, economic, and ecological impacts in coastal areas. Understanding the contribution of TCs to extreme sea levels is therefore essential. In this work we examine the contribution of TCs to annual maximum sea levels at the global scale, including potential climate controls and temporal changes. Complete global coverage (1842-2014) of historical 6-hour best track TC records are obtained from the International Best Track Archive for Climate Stewardship (IBTrACS) data set. Hourly tide gauge data are obtained from the Joint Archive for Sea Level Research Quality Data Set. There are 177 tide gauge stations with at least 25 complete years of data between 1970 and 2014 (a complete year is defined as having more than 90% of all the hourly measurements in a year). We associate an annual maximum sea level at a given station with a TC if the center of circulation of the storm passed within a certain distance from the station within a given time window. Spatial and temporal sensitivity analyses are performed with varying time windows (6h, 12h) and buffer zones (200km and 500km) around the tide gauge stations. Results highlight large regional differences, with some locations experiencing almost ¾ of their annual maxima during the passage of a TC. The attribution of annual maximum sea level to TCs is particularly high along the coastal areas of the eastern United States, the Gulf of Mexico, China, Japan, Taiwan and Western Australia. Further analyses will examine the role played by El Niño - Southern Oscillation and the potential temporal changes in TC contributions to annual maximum sea levels.

  16. Tropical Cyclones in the GISS ModelE2

    Science.gov (United States)

    Camargo, Suzana J.; Sobel, Adam H.; Del Genio, Anthony; Jonas, Jeffrey A.; Kelley, Maxwell; Lu, Yun; Shaevitz, Daniel; Henderson, Naomi

    2016-01-01

    The authors describe the characteristics of tropical cyclone (TC) activity in the GISS general circulation ModelE2 with a horizontal resolution 1deg x 1deg. Four model simulations are analyzed. In the first, the model is forced with sea surface temperature (SST) from the recent historical climatology. The other three have different idealized climate change simulations, namely (1) a uniform increase of SST by 2 deg., (2) doubling of the CO2 concentration and (3) a combination of the two. These simulations were performed as part of the US Climate Variability and Predictability Program Hurricane Working Group. Diagnostics of standard measures of TC activity are computed from the recent historical climatological SST simulation and compared with the same measures computed from observations. The changes in TC activity in the three idealized climate change simulations, by comparison with that in the historical climatological SST simulation, are also described. Similar to previous results in the literature, the changes in TC frequency in the simulation with a doubling CO2 and an increase in SST are approximately the linear sum of the TC frequency in the other two simulations. However, in contrast with previous results, in these simulations the effects of CO2 and SST on TC frequency oppose each other. Large-scale environmental variables associated with TC activity are then analyzed for the present and future simulations. Model biases in the large-scale fields are identified through a comparison with ERA-Interim reanalysis. Changes in the environmental fields in the future climate simulations are shown and their association with changes in TC activity discussed.

  17. Tropical cyclones in the GISS ModelE2

    Directory of Open Access Journals (Sweden)

    Suzana J. Camargo

    2016-07-01

    Full Text Available The authors describe the characteristics of tropical cyclone (TC activity in the GISS general circulation ModelE2 with a horizontal resolution 1°×1°. Four model simulations are analysed. In the first, the model is forced with sea surface temperature (SST from the recent historical climatology. The other three have different idealised climate change simulations, namely (1 a uniform increase of SST by 2 degrees, (2 doubling of the CO2 concentration and (3 a combination of the two. These simulations were performed as part of the US Climate Variability and Predictability Program Hurricane Working Group. Diagnostics of standard measures of TC activity are computed from the recent historical climatological SST simulation and compared with the same measures computed from observations. The changes in TC activity in the three idealised climate change simulations, by comparison with that in the historical climatological SST simulation, are also described. Similar to previous results in the literature, the changes in TC frequency in the simulation with a doubling CO2 and an increase in SST are approximately the linear sum of the TC frequency in the other two simulations. However, in contrast with previous results, in these simulations the effects of CO2 and SST on TC frequency oppose each other. Large-scale environmental variables associated with TC activity are then analysed for the present and future simulations. Model biases in the large-scale fields are identified through a comparison with ERA-Interim reanalysis. Changes in the environmental fields in the future climate simulations are shown and their association with changes in TC activity discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ramsay, Hamish A. [Monash University, Monash Weather and Climate, School of Mathematical Sciences, Clayton, VIC (Australia); Camargo, Suzana J.; Kim, Daehyun [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States)

    2012-08-15

    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 Nino-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 Nino (La Nina) 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. (orig.)

  19. Characteristics of rainfall during tropical cyclone periods in Taiwan

    Directory of Open Access Journals (Sweden)

    K. K. W. Cheung

    2008-12-01

    Full Text Available Due to the Central Mountain Range with an elevation up to about 4 km, the amount and distribution of rainfall in Taiwan associated with typhoons or tropical cyclones (TCs depends not only on the distribution of convection within the TCs (internal structure and influences from monsoon-scale environmental flow, but also on the orographic effect. This study analyzes the spatial and temporal characteristics of rainfall associated with 62 TC cases that affected Taiwan by using observations from the 371 automatic rain stations available in the period 1989–2002. It is found from the climatology maps that highly different rainfall distributions occurred for TCs that approached the Taiwan area from different directions. By performing objective clustering analysis of the rainfall time series of all the rain gauges, several characteristic temporal rainfall profiles are obtained. The geographic distribution of rain gauges that possess a particular temporal profile is also consistent with the possible TC track types that bring maximum rain to the Taiwan area at different times.

    Based on data in the 1989–2002 period, the development of a TC rainfall climatology-persistence (CLIPER model is described. CLIPER is an optimized combination of climatology and persistence with different relative weighting for different forecast periods. Independent cases (other than the model development database during 2003–2004 are used to validate the model. Objective measures like equitable threat score and bias score show that CLIPER's skill is acceptable for practical applications for 24-h rain threshold below 100 mm. However, the underestimation bias for more heavy rainfall is serious and CLIPER seems to have better performance for the northwestern Taiwan than for the other locations. Future directions for improvement of the CLIPER model are discussed.

  20. Impact Factors and Risk Analysis of Tropical Cyclones on a Highway Network.

    Science.gov (United States)

    Yang, Saini; Hu, Fuyu; Jaeger, Carlo

    2016-02-01

    Coastal areas typically have high social and economic development and are likely to suffer huge losses due to tropical cyclones. These cyclones have a great impact on the transportation network, but there have been a limited number of studies about tropical-cyclone-induced transportation network functional damages, especially in Asia. This study develops an innovative measurement and analytical tool for highway network functional damage and risk in the context of a tropical cyclone, with which we explored the critical spatial characteristics of tropical cyclones with regard to functional damage to a highway network by developing linear regression models to quantify their relationship. Furthermore, we assessed the network's functional risk and calculated the return periods under different damage levels. In our analyses, we consider the real-world highway network of Hainan province, China. Our results illustrate that the most important spatial characteristics were location (in particular, the midlands), travel distance, landfalling status, and origin coordinates. However, the trajectory direction did not obviously affect the results. Our analyses indicate that the highway network of Hainan province may suffer from a 90% functional damage scenario every 4.28 years. These results have critical policy implications for the transport sector in reference to emergency planning and disaster reduction. © 2015 Society for Risk Analysis.

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

    Science.gov (United States)

    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. On the angular momentum loss of tropical cyclones: An f-plane approximation

    Science.gov (United States)

    Kang, Hyun-Gyu; Cheong, Hyeong-Bin; Kim, Won-Ho

    2017-12-01

    The angular momentum for ideal axisymmetric tropical cyclones on the f-plane is investigated with a focus on the total-volume integrated quantity. Budget analysis of the momentum equation at cylindrical coordinates shows that a tropical cyclone loses angular momentum during its development and mature stages due to the dynamical difference between the viscous inward-flow near the surface and the angular momentum conserving outward-flow aloft. The total relative angular momentum of a tropical cyclone, as a result, can be negative (i.e., implying anticyclonic rotation as a whole) despite intense cyclonic wind in the tropospheric layers. This anticyclonic rotation was measured in terms of the super-rotation ratio, the ratio of total relative angular momentum to the planetary angular momentum. Simulations with the numerical model of Weather Research and Forecasting (WRF) version 3.4.1 was found to be in favor of the theoretical angular-momentum budget analysis. It was revealed in the numerical simulations that the super-rotation ratio was negative, indicating a sub-rotation, as was predicted by analysis. The sub-rotation ratio was found to be less than one percent for typical tropical cyclones. To show the angular momentum decrease even in the decaying stage, numerical simulations where the thermal forcing by sea surface temperature switched off in the mature stage were carried out. In support of the angular momentum budget analysis, the results indicated that the angular momentum also decreases for a while soon after the forcing was eliminated.

  3. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity

    Science.gov (United States)

    Darby, Stephen E.; Hackney, Christopher R.; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R.; Best, James L.; Nicholas, Andrew P.; Aalto, Rolf

    2016-11-01

    The world’s rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being ‘drowned’ by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world’s great deltas. We demonstrate that spatial variations in the Mekong’s suspended sediment load are correlated (r = 0.765, P < 0.1) with observed variations in tropical-cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world’s major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  4. Ocean feedback to tropical cyclones: Climatology and processes

    Digital Repository Service at National Institute of Oceanography (India)

    Jullien, S.; Marchesiello, P.; Menkes, C.E.; Lefevre, J.; Jourdain, N.C.; Samson, G.; Lengaigne, M.

    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...

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

    Science.gov (United States)

    Grimbacher, Peter S; Stork, Nigel E

    2009-09-01

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

  6. Impact of horizontal resolution on prediction of tropical cyclones over ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The causality figures associated with major cyclones in the Indian sub-continent in the recent past are 2,00,000 and 1,31,000 in Bangladesh in. 1971 and 1991; 10,000 and 1000 in 1977 and 1990 in Andhra Pradesh (India). The super cyclone that crossed Orissa (India) coast on 29th Novem- ber, 1999 affected 129.66lakh ...

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

    Science.gov (United States)

    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.

  8. Assessing the Uncertainty of Tropical Cyclone Simulations in NCAR's Community Atmosphere Model

    OpenAIRE

    Kevin A Reed; Christiane Jablonowski

    2011-01-01

    The paper explores the impact of the initial-data, parameter and structural model uncertainty on the simulation of a tropical cyclone-like vortex in the National Center for Atmospheric Research's (NCAR) Community Atmosphere Model (CAM). An analytic technique is used to initialize the model with an idealized weak vortex that develops into a tropical cyclone over ten simulation days. A total of 78 ensemble simulations are performed at horizontal grid spacings of 1.0°, 0.5° and 0.2...

  9. Tropicalization process of the 7 November 2014 Mediterranean cyclone: Numerical sensitivity study

    Science.gov (United States)

    Carrió, D. S.; Homar, V.; Jansa, A.; Romero, R.; Picornell, M. A.

    2017-11-01

    Tropical-like Mediterranean cyclones (medicanes) have been documented and investigated in the literature, revealing that their physical mechanisms are still poorly understood and likely not unique across cases. During late hours of 7 November 2014 a small-scale cyclone was detected over the Sicilian channel, affecting the Islands of Lampedusa, Pantelleria and Malta. Gust wind values exceeding 42.7 m s- 1 and a pressure drop above 20 hPa in 6 h were registered in Malta. Clear signatures of a well-defined cloud-free eye surrounded with convective activity of axisymmetric character were identifiable through IR satellite imagery during the late stages of the cyclone, resembling the properties of a hurricane. We investigate the cyclogenesis and posterior development of this small-scale cyclone as well as its physical nature; to this aim, a set of high-resolution sensitivity numerical experiments were performed. Hart's phase diagrams adapted to the Mediterranean region clearly reveal the tropical characteristics of the simulated storm. A numerical sensitivity analysis by means of a factor separation technique is used to gain quantitative insight on the roles latent heat release, surface heat fluxes and upper-level PV signatures (dynamically isolated through a PV-Inversion technique) have on the unfold of this singular event. Results show the importance of the upper-level dynamics to generate a baroclinic environment prone to surface cyclogenesis and in supporting the posterior tropicalization of the system. On the contrary, latent heat release and surface heat fluxes factors do not seem to contribute, as individual processes, to the genesis of the cyclone as much as it could be suspected, considering it behaves as a tropical-like cyclone. However, the asynchronous synergism between latent heat release and PV factors plays a crucial role for the intensification of the cyclone towards reaching the pure diabatic phase.

  10. The role of mid-level vortex in the intensification and weakening of tropical cyclones

    Science.gov (United States)

    Kutty, Govindan; Gohil, Kanishk

    2017-10-01

    The present study examines the dynamics of mid-tropospheric vortex during cyclogenesis and quantifies the importance of such vortex developments in the intensification of tropical cyclone. The genesis of tropical cyclones are investigated based on two most widely accepted theories that explain the mechanism of cyclone formation namely `top-down' and `bottom-up' dynamics. The Weather Research and Forecast model is employed to generate high resolution dataset required for analysis. The development of the mid-level vortex was analyzed with regard to the evolution of potential vorticity (PV), relative vorticity (RV) and vertical wind shear. Two tropical cyclones which include the developing cyclone, Hudhud and the non-developing cyclone, Helen are considered. Further, Hudhud and Helen, is compared to a deep depression formed over Bay of Bengal to highlight the significance of the mid-level vortex in the genesis of a tropical cyclone. Major results obtained are as follows: stronger positive PV anomalies are noticed over upper and lower levels of troposphere near the storm center for Hudhud as compared to Helen and the depression; Constructive interference in upper and lower level positive PV anomaly maxima resulted in the intensification of Hudhud. For Hudhud, the evolution of RV follows `top-down' dynamics, in which the growth starts from the middle troposphere and then progresses downwards. As for Helen, RV growth seems to follow `bottom-up' mechanism initiating growth from the lower troposphere. Though, the growth of RV for the depression initiates from mid-troposphere, rapid dissipation of mid-level vortex destabilizes the system. It is found that the formation mid-level vortex in the genesis phase is significantly important for the intensification of the storm.

  11. The influence of tropical cyclones on long-term riverine flooding; examples from tropical Australia

    Science.gov (United States)

    Nott, Jonathan

    2018-02-01

    Luminescence chronologies for two new slackwater flood deposit (SWD) sites (Broken River northeast Queensland and Ord River northwestern Western Australia) are presented and these along with other SWD chronologies from the same regions are compared with recently developed high resolution, isotope tropical cyclones (TC) records. Heightened TC activity occurred between 1400 and 1850 CE in Queensland and between 1500 and 1850 CE in Western Australia. A distinct clustering of flood events in northwest Western Australia during the period of enhanced TC activity suggests the two may be related. The SWD records in northeast Queensland do not cluster specifically during the period of heightened TC activity however several major floods do occur during this time suggesting that TCs may have been involved.

  12. Emergence timescales for detection of anthropogenic climate change in US tropical cyclone loss data

    Energy Technology Data Exchange (ETDEWEB)

    Crompton, Ryan P; McAneney, K John [Risk Frontiers, Macquarie University, NSW, 2109 (Australia); Pielke, Roger A Jr, E-mail: ryan.crompton@mq.edu.au [Center for Science and Technology Policy Research, University of Colorado, Boulder, CO 80309 (United States)

    2011-01-15

    Recent reviews have concluded that efforts to date have yet to detect or attribute an anthropogenic climate change influence on Atlantic tropical cyclone (of at least tropical storm strength) behaviour and concomitant damage. However, the possibility of identifying such influence in the future cannot be ruled out. Using projections of future tropical cyclone activity from a recent prominent study we estimate the time that it would take for anthropogenic signals to emerge in a time series of normalized US tropical cyclone losses. Depending on the global climate model(s) underpinning the projection, emergence timescales range between 120 and 550 years, reflecting a large uncertainty. It takes 260 years for an 18-model ensemble-based signal to emerge. Consequently, under the projections examined here, the detection or attribution of an anthropogenic signal in tropical cyclone loss data is extremely unlikely to occur over periods of several decades (and even longer). This caution extends more generally to global weather-related natural disaster losses.

  13. Tropical cyclones and the flood hydrology of Puerto Rico

    Science.gov (United States)

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

    2005-01-01

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

  14. Solar Influence on Tropical Cyclone in Western North Pacific Ocean

    Science.gov (United States)

    Kim, Jung-Hee; Kim, Ki-Beom; Chang, Heon-Young

    2017-12-01

    Solar activity is known to be linked to changes in the Earth’s weather and climate. Nonetheless, for other types of extreme weather, such as tropical cyclones (TCs), the available evidence is less conclusive. In this study the modulation of TC genesis over the western North Pacific by the solar activity is investigated, in comparison with a large-scale environmental parameter, i.e., El-Niño-Southern Oscillation (ENSO). For this purpose, we have obtained the best track data for TCs in the western North Pacific from 1977 to 2016, spanning from the solar cycle 21 to the solar cycle 24. We have confirmed that in the El-Niño periods TCs tend to form in the southeast, reach its maximum strength in the southeast, and end its life as TSs in the northeast, compared with the La-Niña periods. TCs occurring in the El-Niño periods are found to last longer compared with the La-Niña periods. Furthermore, TCs occurring in the El-Niño periods have a lower central pressure at their maximum strength than those occurring in the La-Niña periods. We have found that TCs occurring in the solar maximum periods resemble those in the El-Niño periods in their properties. We have also found that TCs occurring in the solar descending periods somehow resemble those in the El-Niño periods in their properties. To make sure that it is not due to the ENSO effect, we have excluded TCs both in the El-Niño periods and in the La-Niña periods from the data set and repeated the analysis. In addition to this test, we have also reiterated our analysis twice with TCs whose maximum sustained winds speed exceeds 17 m/s, instead of 33 m/s, as well as TCs designated as a typhoon, which ends up with the same conclusions.

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

    Science.gov (United States)

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

    1998-01-01

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

  16. Impact of tropical cyclone track change on regional air quality.

    Science.gov (United States)

    Lam, Yun Fat; Cheung, Hung Ming; Ying, Chi Cheong

    2018-01-01

    There has been an increase in tropical cyclones (TCs) in the western North Pacific (WNP) that traverse with a northward recurving track towards East Asia and a decrease in TC tracks entering the South China Sea (SCS) in the past few decades. To investigate the potential impact of the prevailing TC track change on Hong Kong air quality, an analysis has been carried out based on historical data (1991 to 2010) of TC tracks and air quality. Compared to TCs in other regions, TCs in the vicinity of Taiwan (Region 2, R2) have the greatest impact on Hong Kong air quality due to regional transport of air pollutants from the highly industrialized Pearl River Delta (PRD). In the last twenty years, the number of days with TCs in R2 (May to October) has increased by 45% from 111days in the period 1991-2000 to 161days in 2001-2010, during which there was an increase in yearly TC-related pollution episodes of approximately 3 episodes per year in Hong Kong. The enhancement of mean O3 concentration due to TCs in R2 is reported as 82% (~50.8μg/m(3) at a rural station) and 58% (~16.8μg/m(3) at an urban station) higher than the summer averages. A similar enhancement is also observed for PM10 (called RSP) and SO2 with an average of 70% (i.e., 22.2μg/m(3)) and 100% (i.e., 15.2μg/m(3)) increases, respectively. Overall, the 20years of historical data show that the O3 concentrations on the TC-affected days are increasing at the estimated rates of 0.5μg/m(3) and 2.6μg/m(3) per year, respectively, in the urban and remote areas, which are significantly higher than the increase of 0.3μg/m(3) and 0.4μg/m(3) per year in the average summer concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  18. Characteristics and development of European cyclones with tropical origin in reanalysis data

    Science.gov (United States)

    Dekker, Mark M.; Haarsma, Reindert J.; Vries, Hylke de; Baatsen, Michiel; Delden, Aarnout J. van

    2017-03-01

    Major storm systems over Europe frequently have a tropical origin. This paper analyses the characteristics and dynamics of such cyclones in the observational record, using MERRA reanalysis data for the period 1979-2013. By stratifying the cyclones along three key phases of their development (tropical phase, extratropical transition and final re-intensification), we identify four radically different life cycles: the tropical cyclone and extratropical cyclone life cycles, the classic extratropical transition and the warm seclusion life cycle. More than 50% of the storms reaching Europe from low latitudes follow the warm seclusion life cycle. It also contains the strongest cyclones. They are characterized by a warm core and a frontal T-bone structure, with a northwestward warm conveyor belt and the effects of dry intrusion. Rapid deepening occurs in the latest phase, around their arrival in Europe. Both baroclinic instability and release of latent heat contribute to the strong intensification. The pressure minimum occurs often a day after entering Europe, which enhances the potential threat of warm seclusion storms for Europe. The impact of a future warmer climate on the development of these storms is discussed.

  19. Characteristics and development of European cyclones with tropical origin in reanalysis data

    Science.gov (United States)

    Dekker, Mark M.; Haarsma, Reindert J.; Vries, Hylke de; Baatsen, Michiel; Delden, Aarnout J. van

    2018-01-01

    Major storm systems over Europe frequently have a tropical origin. This paper analyses the characteristics and dynamics of such cyclones in the observational record, using MERRA reanalysis data for the period 1979-2013. By stratifying the cyclones along three key phases of their development (tropical phase, extratropical transition and final re-intensification), we identify four radically different life cycles: the tropical cyclone and extratropical cyclone life cycles, the classic extratropical transition and the warm seclusion life cycle. More than 50% of the storms reaching Europe from low latitudes follow the warm seclusion life cycle. It also contains the strongest cyclones. They are characterized by a warm core and a frontal T-bone structure, with a northwestward warm conveyor belt and the effects of dry intrusion. Rapid deepening occurs in the latest phase, around their arrival in Europe. Both baroclinic instability and release of latent heat contribute to the strong intensification. The pressure minimum occurs often a day after entering Europe, which enhances the potential threat of warm seclusion storms for Europe. The impact of a future warmer climate on the development of these storms is discussed.

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

    Science.gov (United States)

    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.

  1. Dynamical simulation of tropical cyclones in high-resolution GCMs (Invited)

    Science.gov (United States)

    Strachan, J.; Vidale, P.; Hodges, K.; Roberts, M.

    2010-12-01

    Dynamical simulation of extreme events, such as tropical cyclones, in a global climate context is increasingly possible with improved general circulation model (GCM) resolution, physics, and simulation length. High-resolution GCMs - such as the HiGEM and NUGAM models, developed through the UK High Resolution Global Environmental Modelling (HiGEM) project and the UK Japan Climate Collaboration (UJCC) - now resolve sufficient detail to be able to simulate important aspects of tropical cyclone activity. Using a feature-tracking algorithm, developed at the University of Reading, applied to several hundred years of climate simulations, storms are located and tracked through their lifetime. These simulations have the potential to improve our understanding of the impact of natural variability and change on extreme weather events. We use a hierarchy of GCM resolutions to investigate the role of resolution in the simulation of tropical cyclone activity, in terms of storm location, frequency, structure, intensity, and hence risk. Our results reveal that resolution is not so crucial for the simulating the geographical location of the tropical cyclones, but becomes increasingly crucial for the simulation of storm frequency. Fully simulating storm structure the distribution of storm intensities requires a resolution much higher than is currently possible with GCMs. Assessment of tropical cyclones in a global context using the global modelling approach, although restrictive in terms of horizontal resolution, allows us to: 1. Build a long-term, globally consistent source of dynamically simulated tropical storms under current state of the atmosphere/climate; this reduces reliance on limited and/or inconsistent historical data and provides a much larger storm sample size; 2. Investigate how large scale natural climate variability may influence regional tropical cyclone activity on interannual to multidecadal time scales, and assess how this may alter risk; 3. Analyse of correlated

  2. A simple model for post-landfall intensity changes of tropical cyclone ...

    Indian Academy of Sciences (India)

    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 ...

  3. Preservice Primary Teachers' Depth and Accuracy of Knowledge of Tropical Cyclones

    Science.gov (United States)

    Lane, Rod; Catling, Simon

    2016-01-01

    Climatic hazards are a key feature of life. It is vital that teachers are knowledgeable about these phenomena in order to develop their students' understanding of them. This study used a mixed methods approach to examine the accuracy and depth of preservice primary teachers' (n = 430) knowledge of tropical cyclones. The findings suggest that…

  4. An economic assessment of tropical cyclone risk on offshore wind farms

    DEFF Research Database (Denmark)

    Hong, Lixuan; Möller, Bernd

    2012-01-01

    and cost and setting design parameters for offshore wind turbines are then discussed. The impact of tropical cyclones on offshore wind farms likes a double-edged sword, which might be advantageous for some regions in terms of increasing full-loaded hours of turbines, but also disadvantageous for others due...

  5. Perturbations to the Lower Ionosphere by Tropical Cyclone Evan in the South Pacific Region

    DEFF Research Database (Denmark)

    Kumar, Sushil; Amor, Samir Nait; Chanrion, Olivier

    2017-01-01

    ) observed during tropical cyclone (TC) Evan, 9-16 December 2012 when TC was in the proximity of the transmitter-receiver links. We observed a maximum amplitude perturbation of 5.7dB on JJI transmitter during 16 December event. From Long Wave Propagation Capability model applied to three selected events we...

  6. Thermodynamics of Tropical Cyclones: A Thermodynamic Approach to Nonlinear Non-equilibrium Phenomena

    Science.gov (United States)

    Ozawa, H.; Shimokawa, S.

    2016-12-01

    A formation process of circulatory motion of tropical cyclones is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the 1st and 2nd laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation and dissipation rates of mechanical energy in the fluid system. We find from this formulation and data analysis that the thermodynamic efficiency of tropical cyclones is about 40% lower than the Carnot maximum efficiency because of the presence of thermal dissipation due to irreversible transport of sensible and latent heat in the system. We show that a tropical cyclone tends to develop within a few days through a feedback supply of mechanical energy when the sea surface temperature is higher than 300 K, and when the horizontal scale of circulation becomes larger than the vertical height of the troposphere, being consistent with statistical properties of typhoons observed in the western North Pacific. Applications of this method to other nonlinear non-equilibrium phenomena are also discussed. Ref.) H. Ozawa and S. Shimokawa, Tellus A 67, 24216 (2015).

  7. Tropical cyclone cloud‐top height and vertical temperature structure detection using GPS radio occultation measurements

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Ho, Shu‐Peng; Randel, William

    2013-01-01

    The accurate determination of tropical cyclone (TC) cloud-top height and its vertical thermal structure using the GPS radio occultation (RO) technique is demonstrated in this study. Cloud-top heights are determined by using the bending angle anomaly and the temperature anomaly profiles during the...

  8. ONR Tropical Cyclone Motion Research Initiative; First-Year Review, Discussion and Tentative Hypotheses.

    Science.gov (United States)

    1988-02-01

    Bureau of Meteorology Research Center R. Merrill, University of Wisconsin C. Ramage, University of...for example, Sandgathe, 1987; JTWC Annual Typhoon Reports; Bureau of Meteorology , 1978). A few ". schematic examples in the western North Pacific...Mrs. P. Jones. 32 dI % % % % % REFERENCES " Bureau of Meteorology , 1978: The Australian Tropical Cyclone Forecasting Manual. Bureau of Meteorology ,

  9. GPS radio occultation technique for measurement of the atmosphere above tropical cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

    2009-01-01

    /lower stratosphere (UT/LS). The result is positive, suggesting that the bending angle of a GPS signal contains interesting information on the atmosphere around the tropopause. The presentation is focused on one particular Tropical Cyclone (TC), the hurricane Bertha, which formed in the Atlantic Basin during July...

  10. The Teleconnection Between Atlantic Sea Surface Temperature and Eastern Pacific Tropical Cyclones

    Science.gov (United States)

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

    2016-12-01

    The El Niño-Southern Oscillation (ENSO) is a major source of seasonal tropical cyclone (TC) predictability, in both local and remote ocean basins. Unusually warm eastern tropical Pacific sea-surface temperature (SST) during El Niño tends not only to enhance local TC activity in the eastern North Pacific (ENP) but also to suppress Atlantic TCs via well-known teleconnections. Here, we demonstrate that Atlantic SST variability likewise exerts a significant influence on remote TC activity in the eastern Pacific basin using observations and 27 km resolution tropical channel model simulations. Observed and simulated accumulated cyclone energy in the ENP is substantially reduced during the positive phase of the Atlantic Meridional Mode (AMM), which is characterized by warm and cool SST anomalies in the northern and southern tropical Atlantic respectively, and vice versa during the cool AMM phase. We find that the observed anti-correlation in seasonal TC activity between the Atlantic and ENP basins is driven by interannual climate variability in both the tropical Pacific (ENSO) and Atlantic (AMM). The physical mechanisms that drive the teleconnection between Atlantic SST and ENP TC activity will also be presented. This work provides information that can be used to improve seasonal forecasts and future projections of ENP tropical cyclone activity.

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

    Science.gov (United States)

    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.

  12. Contrasting effects of tropical cyclones on the annual survival of a pelagic seabird in the Indian Ocean.

    Science.gov (United States)

    Nicoll, Malcolm A C; Nevoux, Marie; Jones, Carl G; Ratcliffe, Norman; Ruhomaun, Kevin; Tatayah, Vikash; Norris, Ken

    2017-02-01

    Tropical cyclones are renowned for their destructive nature and are an important feature of marine and coastal tropical ecosystems. Over the last 40 years, their intensity, frequency and tracks have changed, partly in response to ocean warming, and future predictions indicate that these trends are likely to continue with potential consequences for human populations and coastal ecosystems. However, our understanding of how tropical cyclones currently affect marine biodiversity, and pelagic species in particular, is limited. For seabirds, the impacts of cyclones are known to be detrimental at breeding colonies, but impacts on the annual survival of pelagic adults and juveniles remain largely unexplored and no study has simultaneously explored the direct impacts of cyclones on different life-history stages across the annual life cycle. We used a 20-year data set on tropical cyclones in the Indian Ocean, tracking data from 122 Round Island petrels and long-term capture-mark-recapture data to explore the impacts of tropical cyclones on the survival of adult and juvenile (first year) petrels during both the breeding and migration periods. The tracking data showed that juvenile and adult Round Island petrels utilize the three cyclone regions of the Indian Ocean and were potentially exposed to cyclones for a substantial part of their annual cycle. However, only juvenile petrel survival was affected by cyclone activity; negatively by a strong cyclone in the vicinity of the breeding colony and positively by increasing cyclone activity in the Northern Indian Ocean where they spend the majority of their first year at sea. These contrasting effects raise the intriguing prospect that the projected changes in cyclones under current climate change scenarios may have positive as well as the more commonly perceived negative impacts on marine biodiversity. © 2016 John Wiley & Sons Ltd.

  13. Decadal variation of ocean heat content and tropical cyclone activity ...

    Indian Academy of Sciences (India)

    et al. 2007), while the rest goes into melting sea and land ice, and warming the land surface and atmosphere. Therefore, monitoring of the upper ocean thermal structure is important in the study of cyclone–ocean interactions including variation of the cyclone. Thus, the OHC up to a depth of 700 m (OHC700) is considered for ...

  14. Climatology and Landfall of Tropical Cyclones in the South- West ...

    African Journals Online (AJOL)

    Abstract—The climatology of cyclone formation and behaviour in the South-West Indian Ocean, including landfall in Mozambique and Madagascar, has been investigated. The records used were obtained by merging track data from the Joint Typhoon Warning Centre with data from La Reunion – Regional Specialised ...

  15. The response of land-falling tropical cyclone characteristics to projected climate change in northeast Australia

    Science.gov (United States)

    Parker, Chelsea L.; Bruyère, Cindy L.; Mooney, Priscilla A.; Lynch, Amanda H.

    2018-01-01

    Land-falling tropical cyclones along the Queensland coastline can result in serious and widespread damage. However, the effects of climate change on cyclone characteristics such as intensity, trajectory, rainfall, and especially translation speed and size are not well-understood. This study explores the relative change in the characteristics of three case studies by comparing the simulated tropical cyclones under current climate conditions with simulations of the same systems under future climate conditions. Simulations are performed with the Weather Research and Forecasting Model and environmental conditions for the future climate are obtained from the Community Earth System Model using a pseudo global warming technique. Results demonstrate a consistent response of increasing intensity through reduced central pressure (by up to 11 hPa), increased wind speeds (by 5-10% on average), and increased rainfall (by up to 27% for average hourly rainfall rates). The responses of other characteristics were variable and governed by either the location and trajectory of the current climate cyclone or the change in the steering flow. The cyclone that traveled furthest poleward encountered a larger climate perturbation, resulting in a larger proportional increase in size, rainfall rate, and wind speeds. The projected monthly average change in the 500 mb winds with climate change governed the alteration in the both the trajectory and translation speed for each case. The simulated changes have serious implications for damage to coastal settlements, infrastructure, and ecosystems through increased wind speeds, storm surge, rainfall, and potentially increased size of some systems.

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

    Science.gov (United States)

    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 δ18O and δ2H 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 δ18O and δ2H 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.

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

    Directory of Open Access Journals (Sweden)

    Niels C Munksgaard

    Full Text Available 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 δ18O and δ2H 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 δ18O and δ2H 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.

  18. The Cyclone Global Navigation Satellite System (CYGNSS) - Analysis and Data Assimilation for Tropical Convection

    Science.gov (United States)

    Li, Xuanli; Lang, Timothy J.; Mecikalski, John; Castillo, Tyler; Hoover, Kacie; Chronis, Themis

    2017-01-01

    Cyclone Global Navigation Satellite System (CYGNSS): a constellation of 8 micro-satellite observatories launched in November 2016, to measure near-surface oceanic wind speed. Main goal: To monitor surface wind fields of the Tropical Cyclones' inner core, including regions beneath the intense eye wall and rain bands that could not previously be measured from space; Cover 38 deg S -38 deg N with unprecedented temporal resolution and spatial coverage, under all precipitating conditions Low flying satellite: Pass over ocean surface more frequently than one large satellite. A median(mean) revisit time of 2.8(7.2) hrs.

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

    CSIR Research Space (South Africa)

    Malherbe, J

    2014-06-01

    Full Text Available 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...

  20. Tropical Cyclone Exposure for U.S. waters within the Eastern Pacific Ocean basin, 1900-2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent modeled, historical exposure of U.S. offshore and coastal waters to tropical cyclone activity within the Eastern Pacific Ocean basin. BOEM Outer...

  1. Tropical Cyclone Exposure for U.S. waters within the North Atlantic Ocean basin, 1900-2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent modeled, historical exposure of U.S. offshore and coastal waters to tropical cyclone activity within the North Atlantic Ocean basin. BOEM Outer...

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

    Science.gov (United States)

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

    2012-12-01

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

  3. Spatial and Temporal Trends in the Location of the Lifetime Maximum Intensity of Tropical Cyclones

    Directory of Open Access Journals (Sweden)

    Sarah A. Tennille

    2017-10-01

    Full Text Available The climatology of tropical cyclones is an immediate research need, specifically to better understand their long-term patterns and elucidate their future in a changing climate. One important pattern that has recently been detected is the poleward shift of the lifetime maximum intensity (LMI of tropical cyclones. This study further assessed the recent (1977–2015 spatial changes in the LMI of tropical cyclones, specifically those of tropical storm strength or stronger in the North Atlantic and northern West Pacific basins. Analyses of moving decadal means suggested that LMI locations migrated south in the North Atlantic and north in the West Pacific. In addition to a linear trend, there is a cyclical migration of LMI that is especially apparent in the West Pacific. Relationships between LMI migration and intensity were explored, as well as LMI location relative to landfall. The southerly trend of LMI in the North Atlantic was most prevalent in the strongest storms, resulting in these storms reaching their LMI farther from land. The relationship between intensity and LMI migration in the West Pacific was not as clear, but the most intense storms have been reaching LMI closer to their eventual landfall location. This work adds to those emphasizing the importance of understanding the climatology of the most intense hurricanes and shows there are potential human impacts resulting from any migration of LMI.

  4. Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

    OpenAIRE

    Hisashi Ozawa; Shinya Shimokawa

    2015-01-01

    The formation process of circulatory motion of a tropical cyclone is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the first and second laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation ...

  5. Statistical Evaluations of Microphysics Fields From Observations and Simulations of Tropical Cyclones

    Science.gov (United States)

    Rogers, R.; Black, M.; Chen, S.

    2006-12-01

    There are many factors that determine tropical cyclone intensity and rainfall, such as the magnitude and direction of vertical shear of the environmental wind, upper oceanic temperature structure, and low- and mid- level environmental relative humidity. Ultimately, though, intensity and rainfall are dependent on the magnitude and distribution of the release of latent heat within the core of the storm. The ability to accurately predict these fields is quite challenging, however, and improving our understanding and forecasting of intensity and rainfall remains an elusive goal for the operational and research communities. Its importance is underscored by the fact that the improvement in forecast skill for tropical cyclone intensity has significantly lagged behind that for track, while standardized techniques for evaluating tropical cyclone rainfall are only now being developed. The primary means by which forecasts of intensity and rainfall can be improved is through the use of numerical models. Continuing increases in computer power have enabled cloud-scale (grid length O(1 km)), three- dimensional simulations of tropical cyclones to become practically commonplace. Such high resolution obviates the need for the parameterization of deep convection, a traditional source of uncertainty in determining latent heating profiles. While convective parameterization is avoided at this resolution, the necessity of parameterizing other processes, such as hydrometeor production, conversion, and fallout, fluxes of heat, moisture, and momentum from the ocean to the atmosphere, and subgrid-scale turbulent mixing, remains. These parameterizations also have uncertainties and deficiencies that may contribute to errors in tropical cyclone intensity and rainfall forecasts. What is needed is a method for evaluating tropical cyclone simulations by comparing them to an extensive set of observations of microphysics fields, including hydrometeor concentrations, radar reflectivity, and vertical

  6. On the links between meteorological variables, aerosols, and tropical cyclone frequency in individual ocean basins

    Science.gov (United States)

    Chiacchio, Marc; Pausata, Francesco S. R.; Messori, Gabriele; Hannachi, Abdel; Chin, Mian; Önskog, Thomas; Ekman, Annica M. L.; Barrie, Leonard

    2017-01-01

    A generalized linear model based on Poisson regression has been used to assess the impact of environmental variables modulating tropical cyclone frequency in six main cyclone development areas: the East Pacific, West Pacific, North Atlantic, North Indian, South Indian, and South Pacific. The analysis covers the period 1980-2009 and focuses on widely used meteorological parameters including wind shear, sea surface temperature, and relative humidity from different reanalyses as well as aerosol optical depth for different compounds simulated by the Goddard Chemistry Aerosol Radiation and Transport model. Circulation indices are also included. Cyclone frequency is obtained from the International Best Track Archive for Climate Stewardship. A strong link is found between cyclone frequency and the relative sea surface temperature, Atlantic Meridional Mode, and wind shear with significant explained log likelihoods in the North Atlantic of 37%, 27%, and 28%, respectively. A significant impact of black carbon and organic aerosols on cyclone frequency is found over the North Indian Ocean, with explained log likelihoods of 27%. A weaker but still significant impact is found for observed dust aerosols in the North Atlantic with an explained log likelihood of 11%. Changes in lower stratospheric temperatures explain 28% of the log likelihood in the North Atlantic. Lower stratospheric temperatures from a subset of Coupled Model Intercomparison Project Phase 5 models properly simulate the warming and subsequent cooling of the lower stratosphere that follows a volcanic eruption but underestimates the cooling by about 0.5°C.

  7. Impacts of category 5 tropical cyclone Fantala (April 2016) on Farquhar Atoll, Seychelles Islands, Indian Ocean

    Science.gov (United States)

    Duvat, Virginie K. E.; Volto, Natacha; Salmon, Camille

    2017-12-01

    This paper provides new insights on the impacts of a category 5 tropical cyclone on Indian Ocean atoll reef islands. Using multi-date aerial imagery and field observations, the contribution of tropical cyclone Fantala to shoreline and island change, and to sediment production and transport, was assessed on Farquhar Atoll, Seychelles Islands. Results show that the two largest islands (> 3 km2) only suffered limited land loss (- 1.19 to - 8.35%) while small islets lost 13.17 to 28.45% of their initial land area. Islands and islets exhibited contrasting responses depending on their location, topography and vegetation type. Depending on islands, the retreat of the vegetation line occurred either along all shorelines, or along ocean shoreline only. The structure (wooded vs. grassy) and origin (native vs. introduced) of the vegetation played a major role in island response. Five days after the cyclone, beach width and beach area were multiplied by 1.5 to 10, depending on the setting, and were interpreted as resulting from both sediment reworking and the supply of large amounts of fresh sediments by the reef outer slopes to the island system. Fourth months after the cyclone, extended sheets of loose sediments were still present on the reef flat and in inter-islet channels and shallow lagoon waters, indicating continuing sediment transfer to islands. As a reminder (see Section 3.1.4), beach width uncertainty equals to 6 m for all beach sections.

  8. Daily tropical cyclone intensity response to solar ultraviolet radiation

    Science.gov (United States)

    Elsner, J. B.; Jagger, T. H.; Hodges, R. E.

    2010-05-01

    An inverse relationship between hurricane activity over the Caribbean and the number of sunspots has recently been identified. Here we investigate this relationship using daily observations and find support for the hypothesis that changes in ultraviolet (UV) radiation rather than changes in other concomitant solar and cosmic variations are the cause. The relationship is statistically significant after accounting for annual variation in ocean heat and the El Niño cycle. A warming response in the upper troposphere to increased solar UV forcing as measured by the Mg II index (core-to-wing ratio) decreases the atmosphere's convective available potential energy leading to a weaker cyclone. The response amplitude at a cyclone intensity of 44 m s-1 is 6.7 ± 2.56 m s-1 per 0.01 Mg II units (s.d.), which compares with 4.6 m s-1 estimated from the heat-engine theory using a temperature trend derived from observations. The increasing hurricane response sensitivity with increasing strength is found in the observations and in an application of the theory.

  9. Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2014

    Science.gov (United States)

    Wilson, Robert M.

    2016-01-01

    This Technical Publication (TP) represents an extension of previous work concerning the tropical cyclone activity in the North Atlantic basin during the weather satellite era, 1960-2014, in particular, that of an article published in The Journal of the Alabama Academy of Science. With the launch of the TIROS-1 polar-orbiting satellite in April 1960, a new era of global weather observation and monitoring began. Prior to this, the conditions of the North Atlantic basin were determined only from ship reports, island reports, and long-range aircraft reconnaissance. Consequently, storms that formed far from land, away from shipping lanes, and beyond the reach of aircraft possibly could be missed altogether, thereby leading to an underestimate of the true number of tropical cyclones forming in the basin. Additionally, new analysis techniques have come into use which sometimes has led to the inclusion of one or more storms at the end of a nominal hurricane season that otherwise would not have been included. In this TP, examined are the yearly (or seasonal) and 10-year moving average (10-year moving average) values of the (1) first storm day (FSD), last storm day (LSD), and length of season (LOS); (2) frequencies of tropical cyclones (by class); (3) average peak 1-minute sustained wind speed () and average lowest pressure (); (4) average genesis location in terms of north latitudinal () and west longitudinal () positions; (5) sum and average power dissipation index (); (6) sum and average accumulated cyclone energy (); (7) sum and average number of storm days (); (8) sum of the number of hurricane days (NHD) and number of major hurricane days (NMHD); (9) net tropical cyclone activity index (NTCA); (10) largest individual storm (LIS) PWS, LP, PDI, ACE, NSD, NHD, NMHD; and (11) number of category 4 and 5 hurricanes (N4/5). Also examined are the December-May (D-M) and June-November (J-N) averages and 10-year moving average values of several climatic factors, including the (1

  10. United States and Caribbean tropical cyclone activity related to the solar cycle

    Science.gov (United States)

    Elsner, J. B.; Jagger, T. H.

    2008-09-01

    The authors report on a finding that annual U.S hurricane counts are significantly related to solar activity. The relationship results from fewer intense tropical cyclones over the Caribbean and Gulf of Mexico when sunspot numbers are high. The finding is in accord with the heat-engine theory of hurricanes that predicts a reduction in the maximum potential intensity with a warming in the layer near the top of the hurricane. An active sun warms the lower stratosphere and upper troposphere through ozone absorption of additional ultraviolet (UV) radiation. Since the dissipation of the hurricane's energy occurs through ocean mixing and atmospheric transport, tropical cyclones can act to amplify the effect of relatively small changes in the sun's output thereby appreciably altering the climate. Results have implications for life and property throughout the Caribbean, Mexico, and portions of the United States.

  11. Objectively determined model derived parameters associated with forecasts of tropical cyclone formation

    OpenAIRE

    Cowan, Christy G.

    2006-01-01

    During the 2005 North Atlantic hurricane season, an objective tropical cyclone vortex identification and tracking technique was applied to analyzed and forecast fields of three global operational numerical models- the National Centers for Environmental Prediction Global Forecast System (GFS), the Navy Operational Global Atmospheric Prediction System (NOGAPS), and the United Kingdom Meteorological Office model (UKMET). For the purpose of evaluating each model's performance with respect to fore...

  12. Improvement of High-Resolution Tropical Cyclone Structure and Intensity Forecasts using COAMPS-TC

    Science.gov (United States)

    2012-09-30

    north and east of the center. This large shield of heavy precipitation caused severe river flooding as it slowly moved north through the mid...invited) Doyle, J.D., 2011: An Overview of NRL’s COAMPS System and Physics. EMC Physics Workshop. 26-27 July 2011, NCEP/ EMC . Doyle, J.D., C...Overview of the COAMPS-TC Tropical Cyclone Boundary Layer Parameterization. HFIP Physics Workshop. 9-11 August 2011, NCEP/ EMC . 8 Hendricks, E

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

    Science.gov (United States)

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

    2015-10-13

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

  14. Recent Colorado State University Tropical Cyclone Research of Interest to Forecasters

    Science.gov (United States)

    1987-06-01

    inner-core convection by Marks and Houze (1985) has docunented some cases of a secondary maximum in upper level vertical motion within the TC’s...tropical cyclone structural changes. .Qjignt. J. JfiX- Meteor. ^^.. 110, 723-745. Marks, F. D., Jr., and R. A. Houze , Jr., 1985: Inner...the author has had many beneficial discussions. This Includes: Dr. Robert Merrill; Llanshou Chen and Ding-wen Wei of the PRC; Cheng- Shang Lee

  15. An Observational Study of Tropical Cyclone Spin-Up in Supertyphoon Jangmi and Hurricane Georges

    Science.gov (United States)

    2011-12-01

    thanks to Robert LeeJoice for assistance with IDL code and being a great office mate. I thank the 53rd Weather Reconnaissance Squadron “Hurricane...hurricane was Robert Simpson, who co-developed the Saffir-Simpson scale of hurricane intensity with Herbert Saffir. While flying in the eye of Typhoon...also with previous studies of various asymmetric features of tropical cyclones using airborne Doppler radar and dropsonde data (Marks and Houze 1984

  16. Rainfall Generated By The Incidence Of Two Simultaneous Tropical Cyclones In Mexico

    Science.gov (United States)

    Fernandez, D. C.; Brena-Naranjo, J. A. A.; Pedrozo-Acuña, A.

    2014-12-01

    The objective of this study is to characterize the registered rainfall originated from the simultaneous incidence of two tropical cyclones in Mexico, during September 2013. Tropical Storm Manuel in the Pacific and Hurricane Ingrid (category 1) in the Gulf of Mexico, made landfall during a 24 hours period on September 15 and 18, 2013. Both systems, affected 77% of Mexican territory with heavy rainfall producing landslides and severe flooding. The unprecedented occurrence of two simultaneous tropical cyclones, along with the large damages registered in the country; make evident the need for a careful examination of the rainfall produced by their simultaneous incidence. For this, we utilize information from the Tropical Rainfall Measurement Mission (TRMM), in combination with data from the rain gauge observations (from 1st to 16th September 2013). The selected remotely sensed products correspond to the TRMM Multi-Satellite Precipitation Analysis (TMPA), 3B42RT and 3B42V7. Additionally, we estimate the performance of the TRMM products through well-known error metrics derived from the comparison of both, registered rainfall by rain gauges and that determined from 607 TMPA cells (0.25° x 0.25° containing at least one rain gauge). Results show that rainfall produced by the incidence of both storms, is similar to that registered as if the events occurred separately, accounting for about 10% of the annual precipitation total of 2013. Moreover, spatially averaged results indicate that the product 3B42V7 is a good estimate of daily precipitation across the country, while the TMPA 3B42RT product underestimates the amount of rainfall due to cyclonic events. Therefore, TMPA products provide acceptable estimates of rainfall for large-scale cyclonic events.

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

    OpenAIRE

    Kevin Reed; Christiane Jablonowski

    2012-01-01

    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 ae...

  18. Impact of resolution and downscaling technique in simulating recent Atlantic tropical cyclone activity

    Energy Technology Data Exchange (ETDEWEB)

    Caron, Louis-Philippe; Winger, Katja [CRCMD Network, UQAM, Montreal, QC (Canada); Jones, Colin G. [Swedish Meteorological and Hydrological Institute, Rossby Centre, Norrkoping (Sweden)

    2011-09-15

    Using the global environmental multiscale (GEM) model, we investigate the impact of increasing model resolution from 2 to 0.3 on Atlantic tropical cyclone activity. There is a clear improvement in the realism of Atlantic storms with increased resolution, in part, linked to a better representation of African easterly waves. The geographical distribution of a Genesis Potential Index, composed of large-scales fields known to impact cyclone formation, coincides closely in the model with areas of high cyclogenesis. The geographical distribution of this index also improves with resolution. We then compare two techniques for achieving local high resolution over the tropical Atlantic: a limited-area model driven at the boundaries by the global 2 GEM simulation and a global variable resolution model (GVAR). The limited-area domain and high-resolution part of the GVAR model coincide geographically, allowing a direct comparison between these two downscaling options. These integrations are further compared with a set of limited-area simulations employing the same domain and resolution, but driven at the boundaries by reanalysis. The limited-area model driven by reanalysis produces the most realistic Atlantic tropical cyclone variability. The GVAR simulation is clearly more accurate than the limited-area version driven by GEM-Global. Degradation in the simulated interannual variability is partly linked to the models failure to accurately reproduce the impact of atmospheric teleconnections from the equatorial Pacific and Sahel on Atlantic cyclogenesis. Through the use of a smaller limited-area grid, driven by GEM-Global 2 , we show that an accurate representation of African Easterly Waves is crucial for simulating Atlantic tropical cyclone variability. (orig.)

  19. Degree of simulated suppression of Atlantic tropical cyclones modulated by flavour of El Niño

    Science.gov (United States)

    Patricola, Christina M.; Chang, Ping; Saravanan, R.

    2016-02-01

    El Niño/Southern Oscillation, the dominant mode of interannual climate variability, strongly influences tropical cyclone activity. During canonical El Niño, the warm phase, Atlantic tropical cyclones are suppressed. However, the past decades have witnessed different El Niño characteristics, ranging from warming over the east Pacific cold tongue in canonical events to warming near the warm pool, known as warm pool El Niño or central Pacific El Niño. Global climate models project possible future increases in intensity of warm pool El Niño. Here we use a climate model at a resolution sufficient to explicitly simulate tropical cyclones to investigate how these flavours of El Niño may affect such cyclones. We show that Atlantic tropical cyclones are suppressed regardless of El Niño type. For the warmest 10% of each El Niño flavour, warm pool El Niño is substantially less effective at suppressing Atlantic tropical cyclones than cold tongue El Niño. However, for the same absolute warming intensity, the opposite is true. This is because less warming is required near the warm pool to satisfy the sea surface temperature threshold for deep convection, which leads to tropical cyclone suppression through vertical wind shear enhancements. We conclude that an understanding of future changes in not only location, but also intensity and frequency, of El Niño is important for forecasts and projections of Atlantic tropical cyclone activity.

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

    Science.gov (United States)

    Schönemann, D. B.; Frisius, T.

    2012-04-01

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

  1. A Multiple Linear Regression Model for Tropical Cyclone Intensity Estimation from Satellite Infrared Images

    Directory of Open Access Journals (Sweden)

    Yong Zhao

    2016-03-01

    Full Text Available An objectively trained model for tropical cyclone intensity estimation from routine satellite infrared images over the Northwestern Pacific Ocean is presented in this paper. The intensity is correlated to some critical signals extracted from the satellite infrared images, by training the 325 tropical cyclone cases from 1996 to 2007 typhoon seasons. To begin with, deviation angles and radial profiles of infrared images are calculated to extract as much potential predicators for intensity as possible. These predicators are examined strictly and included into (or excluded from the initial predicator pool for regression manually. Then, the “thinned” potential predicators are regressed to the intensity by performing a stepwise regression procedure, according to their accumulated variance contribution rates to the model. Finally, the regressed model is verified using 52 cases from 2008 to 2009 typhoon seasons. The R2 and Root Mean Square Error are 0.77 and 12.01 knot in the independent validation tests, respectively. Analysis results demonstrate that this model performs well for strong typhoons, but produces relatively large errors for weak tropical cyclones.

  2. Rapid wave and storm surge warning system for tropical cyclones in Mexico

    Science.gov (United States)

    Appendini, C. M.; Rosengaus, M.; Meza, R.; Camacho, V.

    2015-12-01

    The National Hurricane Center (NHC) in Miami, is responsible for the forecast of tropical cyclones in the North Atlantic and Eastern North Pacific basins. As such, Mexico, Central America and Caribbean countries depend on the information issued by the NHC related to the characteristics of a particular tropical cyclone and associated watch and warning areas. Despite waves and storm surge are important hazards for marine operations and coastal dwellings, their forecast is not part of the NHC responsibilities. This work presents a rapid wave and storm surge warning system based on 3100 synthetic tropical cyclones doing landfall in Mexico. Hydrodynamic and wave models were driven by the synthetic events to create a robust database composed of maximum envelops of wind speed, significant wave height and storm surge for each event. The results were incorporated into a forecast system that uses the NHC advisory to locate the synthetic events passing inside specified radiuses for the present and forecast position of the real event. Using limited computer resources, the system displays the information meeting the search criteria, and the forecaster can select specific events to generate the desired hazard map (i.e. wind, waves, and storm surge) based on the maximum envelop maps. This system was developed in a limited time frame to be operational in 2015 by the National Hurricane and Severe Storms Unit of the Mexican National Weather Service, and represents a pilot project for other countries in the region not covered by detailed storm surge and waves forecasts.

  3. Unit 148 - World Wide Web Basics

    OpenAIRE

    148, CC in GIScience; Yeung, Albert K.

    2000-01-01

    This unit explains the characteristics and the working principles of the World Wide Web as the most important protocol of the Internet. Topics covered in this unit include characteristics of the World Wide Web; using the World Wide Web for the dissemination of information on the Internet; and using the World Wide Web for the retrieval of information from the Internet.

  4. Tropical cyclones and permanent El Niño in the early Pliocene epoch.

    Science.gov (United States)

    Fedorov, Alexey V; Brierley, Christopher M; Emanuel, Kerry

    2010-02-25

    Tropical cyclones (also known as hurricanes and typhoons) are now believed to be an important component of the Earth's climate system. In particular, by vigorously mixing the upper ocean, they can affect the ocean's heat uptake, poleward heat transport, and hence global temperatures. Changes in the distribution and frequency of tropical cyclones could therefore become an important element of the climate response to global warming. A potential analogue to modern greenhouse conditions, the climate of the early Pliocene epoch (approximately 5 to 3 million years ago) can provide important clues to this response. Here we describe a positive feedback between hurricanes and the upper-ocean circulation in the tropical Pacific Ocean that may have been essential for maintaining warm, El Niño-like conditions during the early Pliocene. This feedback is based on the ability of hurricanes to warm water parcels that travel towards the Equator at shallow depths and then resurface in the eastern equatorial Pacific as part of the ocean's wind-driven circulation. In the present climate, very few hurricane tracks intersect the parcel trajectories; consequently, there is little heat exchange between waters at such depths and the surface. More frequent and/or stronger hurricanes in the central Pacific imply greater heating of the parcels, warmer temperatures in the eastern equatorial Pacific, warmer tropics and, in turn, even more hurricanes. Using a downscaling hurricane model, we show dramatic shifts in the tropical cyclone distribution for the early Pliocene that favour this feedback. Further calculations with a coupled climate model support our conclusions. The proposed feedback should be relevant to past equable climates and potentially to contemporary climate change.

  5. A global historical data set of tropical cyclone exposure (TCE-DAT)

    Science.gov (United States)

    Geiger, Tobias; Frieler, Katja; Bresch, David N.

    2018-01-01

    Tropical cyclones pose a major risk to societies worldwide, with about 22 million directly affected people and damages of USD 29 billion on average per year over the last 20 years. While data on observed cyclones tracks (location of the center) and wind speeds are publicly available, these data sets do not contain information about the spatial extent of the storm and people or assets exposed. Here, we apply a simplified wind field model to estimate the areas exposed to wind speeds above 34, 64, and 96 knots (kn). Based on available spatially explicit data on population densities and gross domestic product (GDP) we estimate (1) the number of people and (2) the sum of assets exposed to wind speeds above these thresholds accounting for temporal changes in historical distribution of population and assets (TCE-hist) and assuming fixed 2015 patterns (TCE-2015). The associated spatially explicit and aggregated country-event-level exposure data (TCE-DAT) cover the period 1950 to 2015 and are freely available at https://doi.org/10.5880/pik.2017.011" target="_blank">https://doi.org/10.5880/pik.2017.011 (Geiger at al., 2017c). It is considered key information to (1) assess the contribution of climatological versus socioeconomic drivers of changes in exposure to tropical cyclones, (2) estimate changes in vulnerability from the difference in exposure and reported damages and calibrate associated damage functions, and (3) build improved exposure-based predictors to estimate higher-level societal impacts such as long-term effects on GDP, employment, or migration. We validate the adequateness of our methodology by comparing our exposure estimate to estimated exposure obtained from reported wind fields available since 1988 for the United States. We expect that the free availability of the underlying model and TCE-DAT will make research on tropical cyclone risks more accessible to non-experts and stakeholders.

  6. The Formation of Concentric Eyewalls with Heat Sink in a Simple Tropical Cyclone Model

    Directory of Open Access Journals (Sweden)

    Jia-Yi Peng

    2006-01-01

    Full Text Available A linearized, two-layer axisymmetric model analogous to Schubert el al. (1980 is used to simulate the formation of concentric eyewalls in an ideal strong tropical cyclone. By imposing a heat sink near the center of a cyclone the induced perturbation wind, through thermodynamic adjustment to the heat sink, forms a double-peak structure when the disturbance is added to the basic state tangential wind. The heat sink represents, in a crude way, evaporative cooling of precipitation falling from cloud during late stage convective activity or a cooling through environmental advection. Detailed profiling of the induced double-peak wind structure is dependent on the radial profile of the imposed heat sink. After the double-peak tangential wind structure is formed, if a heat source corresponding to a new convective activity is generated inside the outer maximum tangential wind, the outer eyewall contracts and strengthens while the inner eyewall weakens. This result suggests that thermodynamic adjustments to changes in the heating of a tropical-cyclone-core region may contribute to the formation of the double-eyewall phenomenon.

  7. Study of tropical cyclone "Fanoos" using MM5 model – a case study

    Directory of Open Access Journals (Sweden)

    S. Ramalingeswara Rao

    2009-01-01

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

  8. The influence of tropical cyclones in gully formation: A case study from Madagascar

    Science.gov (United States)

    Raveloson, Andrea; Szabó, Amanda; Székely, Balázs

    2017-04-01

    Soil erosion has been recognized as the main cause of land degradation worldwide and gully erosion is currently considered as one of the most striking erosion type. Madagascar is one of the most affected country with special gullies called lavakas. Despite of the several decade long research, the reasons and the mechanism of their formation are still unknown. Anthropogenic factors, specific combination of lithology, weathering profile and topography are most often stated but numerous publications mention climate as a main factor. We studied the role of climatic conditions and tropical cyclones since 2014. This study aims to analyze lavaka distribution with GIS methods and to find relation between lavaka density, lavaka density change and climatic conditions. Lavakas have been identified in 17 selected study sites by visual recognition using satellite images from years 2000-2009 and 2003-2008. A total of 1330 km2 has been processed at 1 km x 1 km grid cell scale. The total number of recognized lavakas was 1592 in the 17 sites that corresponds to a varying lavaka density of 0 and 8.53 km-2. Data show that the appearance of lavakas is related to the spatial distribution and the inter-annual variability of precipitation and this connection is further strengthened by the tropical cyclones. Furthermore, among our 17 study sites changes in lavaka density were observed between 2000-2009 and 2003-2008 only in areas frequently hit by cyclones in the last 20 years.

  9. Sedimentary record of Tropical Cyclone Pam from Vanuatu: implications for long-term event records in the tropical South Pacific

    Science.gov (United States)

    Pilarczyk, Jessica; Kosciuch, Thomas; Hong, Isabel; Fritz, Hermann; Horton, Benjamin; Wallace, Davin; Dike, Clayton; Rarai, Allan; Harrison, Morris; Jockley, Fred

    2017-04-01

    Vanuatu has a history of tropical cyclones impacting its coastlines, including Tropical Cyclone (TC) Pam, a rare Category 5 event that made landfall in March 2015. Reliable records of tropical cyclones impacting Vanuatu are limited to the last several decades, with only fragmentary evidence of events extending as far back as the 1890's. Geological investigations are a means for expanding the short historical record of tropical cyclones by hundreds to thousands of years, permitting the study of even the rare, but intense events. However, geological records of past tropical cyclones are limited in their ability to quantify the intensity of past events. Modern analogues of landfalling tropical cyclones present an opportunity to characterize overwash sediments deposited by a storm of known intensity. In this study, we document the sedimentological and micropaleontological characteristics of sediments deposited by TC Pam in order to assess sediment provenance associated with a landfalling Category 5 storm. Within three months of TC Pam making landfall on Vanuatu we surveyed high-water marks associated with the storm surge and documented the foraminiferal assemblages and grain size distributions contained within the overwash sediments from Manuro (mixed-carbonate site on Efate Island) and Port Resolution Bay (volcaniclastic site on Tanna Island). The combined use of foraminiferal taxonomy and taphonomy (surface condition of foraminifera) was most useful in distinguishing the TC Pam sediments from the underlying layer. TC Pam sediments were characterized by an influx of calcareous marine foraminifera that were dominantly unaltered relative to those that were abraded and fragmented. Similar to studies that use mollusk taphonomy to identify overwash deposits, we found that TC Pam sediments were associated with an influx of angular fragments that were broken during transport by the storm surge. A statistical comparison of foraminifera from six modern environments on Efate

  10. A teleconnection between Atlantic sea surface temperature and eastern and central North Pacific tropical cyclones

    Science.gov (United States)

    Patricola, Christina M.; Saravanan, R.; Chang, Ping

    2017-01-01

    The El Niño-Southern Oscillation (ENSO) is a major source of seasonal tropical cyclone (TC) predictability in both local and remote ocean basins. Unusually warm eastern-central equatorial Pacific sea surface temperature (SST) during El Niño tends to enhance eastern and central North Pacific (ECNP) TCs and suppress Atlantic TCs. Here we demonstrate that Atlantic SST variability likewise influences remote TC activity in the eastern-central Pacific through a Walker Circulation-type response analogous to the ENSO-Atlantic TC teleconnection, using observations and 27 km resolution tropical channel model (TCM) simulations. Observed and simulated ECNP TC activity is reduced during the positive Atlantic Meridional Mode (AMM), which is characterized by warm northern and cool southern tropical Atlantic SST anomalies, and vice versa during the negative AMM. Large ensembles of TCM simulations indicate that SST variability, rather than internal atmospheric variability, drives extreme ECNP hurricane seasons.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2009-05-12

    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 CO(2) 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.

  13. Chlorophyll bloom in response to tropical cyclone Hudhud in the Bay of Bengal: Bio-Argo subsurface observations

    Science.gov (United States)

    Chacko, Neethu

    2017-06-01

    Though previous studies have documented substantial increases in chlorophyll concentrations as a result of cyclones, most of them were based on satellite observations dealing with surface chlorophyll blooms. This study documents the subsurface biological response and the subsequent chlorophyll bloom observed in response to the tropical cyclone Hudhud as evident from a Bio-Argo float located at the central Bay of Bengal. Results show high chlorophyll concentrations of up to 4.5 mg m-3 which is anomalous in the normally warm, stratified, and oligotrophic Bay of Bengal. The chlorophyll bloom is attributed to the combined effect of subsurface chlorophyll entrainment and nutrient injection. The presence of a pre-existing cyclonic eddy and the decreased translation speed of the cyclone over this region could have played a role in inducing the biological response. This is the first ever report to document the evolution of a subsurface chlorophyll bloom in response to cyclone forcing using Bio-Argo observations.

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

    Science.gov (United States)

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

    2015-04-01

    Groundwater in the Todos Santos watershed in southern Baja California, and throughout the peninsula south of latitude 28°N, has values of (δ18 O‰, δD‰) 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 δ18O values50 mm) at least once every 2 to 3 years, and along the Pacific coast between Jalisco and Oaxaca. © 2014, National Ground Water Association.

  15. Multi-hazard risk assessment of coastal vulnerability from tropical cyclones - A GIS based approach for the Odisha coast.

    Science.gov (United States)

    Sahoo, Bishnupriya; Bhaskaran, Prasad K

    2018-01-15

    The coastal region bordering the East coast of India is a thickly populated belt exposed to high risk and vulnerability from natural hazards such as tropical cyclones. Tropical cyclone frequencies that develop over the Bay of Bengal (average of 5-6 per year) region are much higher as compared to the Arabian Sea thereby posing a high risk factor associated with storm surge, inland inundation, wind gust, intense rainfall, etc. The Odisha State in the East coast of India experiences the highest number of cyclone strikes as compared to West Bengal, Andhra Pradesh, and Tamil Nadu. To express the destructive potential resulting from tropical cyclones the Power Dissipation Index (PDI) is a widely used metric globally. A recent study indicates that PDI for cyclones in the present decade have increased about six times as compared to the past. Hence there is a need to precisely ascertain the coastal vulnerability and risk factors associated with high intense cyclones expected in a changing climate. As such there are no comprehensive studies attempted so far on the determination of Coastal Vulnerability Index (CVI) for Odisha coast that is highly prone to cyclone strikes. With this motivation, the present study makes an attempt to investigate the physical, environmental, social, and economic impacts on coastal vulnerability associated with tropical cyclones for the Odisha coast. The study also investigates the futuristic projection of coastal vulnerability over this region expected in a changing climate scenario. Eight fair weather parameters along with storm surge height and onshore inundation were used to estimate the Physical Vulnerability Index (PVI). Thereafter, the PVI along with social, economic, and environmental vulnerability was used to determine the overall CVI using the GIS based approach. The authors believe that the comprehensive nature of this study is expected to benefit coastal zone management authorities. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  17. Analysis and prediction of integrated kinetic energy in Atlantic tropical cyclones

    Science.gov (United States)

    Kozar, Michael E.

    Integrated kinetic energy (IKE) is a recently developed metric that approximates the destructive potential of a tropical cyclone by assessing the size and strength of its wind field. Despite the potential usefulness of the IKE metric, there are few, if any, operational tools that are specifically designed to forecast IKE in real-time. Therefore, IKE and tropical cyclone structure are analyzed within historical Atlantic tropical cyclones from the past two decades in order to develop an understanding of the environmental and internal storm-driven processes that govern IKE variability. This analysis concurs with past research that IKE growth and decay is influenced by both traditional tropical cyclone development mechanisms and by other features such as extratropical transition and trough interactions. Using this framework, a series of statistical prediction tools are created in an effort to project IKE in Atlantic tropical cyclones from a series of relevant normalized input parameters. The resulting IKE prediction schemes are titled the "Statistical Prediction of Integrated Kinetic Energy (SPIKE)". The first version of SPIKE utilizes simple linear regression to project historical IKE quantities in a perfect prognostic mode for all storms between 1990 and 2011. This primitive model acts as a proof of concept, revealing that IKE can be skillfully forecasted relative to persistence out to 72 hours by even the simplest of statistical models if given accurate estimates of various metrics measured throughout the storm and its environment. The proof-of-concept version of SPIKE is improved upon in its second version, SPIKE2, by incorporating a more sophisticated system of adaptive statistical models. A system of artificial neural networks replaces the linear regression model to better capture the nonlinear relationships in the TC-environment system. In a perfect prognostic approach with analyzed input parameters, the neural networks outperform the linear models in nearly

  18. Dynamical system analysis of a low-order tropical cyclone model

    Directory of Open Access Journals (Sweden)

    Daria Schönemann

    2012-02-01

    Full Text Available Tropical cyclone dynamics is investigated by means of a conceptual box model. The tropical cyclone (TC is divided into three regions, the eye, eyewall and ambient region. The model forms a low-order dynamical system of three ordinary differential equations. These are based on entropy budget equations comprising processes of surface enthalpy transfer, entropy advection, convection and radiative cooling. For tropical ocean parameter settings, the system possesses four non-trivial steady state solutions when the sea surface temperature (SST is above a critical value. Two steady states are unstable while the two remaining states are stable. Bifurcation diagrams provide an explanation why only finite-amplitude perturbations above a critical SST can transform into TCs. Besides SST, relative humidity of the ambient region forms an important model parameter. The surfaces that describe equilibria as a function of SST and relative humidity reveal a cusp-catastrophe where the two non-trivial equilibria split into four. Within the model regime of four equilibria, cyclogenesis becomes very unlikely due to the repelling and attracting effects of the two additional equilibria. The results are in qualitative agreement with observations and evince the relevance of the simple model approach to the dynamics of TC formation and its maximum potential intensity.

  19. Drifting buoy data from buoy casts in a world wide distribution as part of the Tropical Ocean Global Atmosphere (TOGA) from 1989-07-01 to 1989-07-31 (NODC Accession 8900227)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drifting buoy data were collected using buoy casts in a world wide distribution from July 1, 1989, to July 31, 1989. Data were submitted by National Data Buoy Center...

  20. Observed air-sea interactions in tropical cyclone Isaac over Loop Current mesoscale eddy features

    Science.gov (United States)

    Jaimes, Benjamin; Shay, Lynn K.; Brewster, Jodi K.

    2016-12-01

    Air-sea interactions during the intensification of tropical storm Isaac (2012) into a hurricane, over warm oceanic mesoscale eddy features, are investigated using airborne oceanographic and atmospheric profilers. Understanding these complex interactions is critical to correctly evaluating and predicting storm effects on marine and coastal facilities in the Gulf of Mexico, wind-driven mixing and transport of suspended matter throughout the water column, and oceanic feedbacks on storm intensity. Isaac strengthened as it moved over a Loop Current warm-core eddy (WCE) where sea surface warming (positive feedback mechanism) of ∼0.5 °C was measured over a 12-h interval. Enhanced bulk enthalpy fluxes were estimated during this intensification stage due to an increase in moisture disequilibrium between the ocean and atmosphere. These results support the hypothesis that enhanced buoyant forcing from the ocean is an important intensification mechanism in tropical cyclones over warm oceanic mesoscale eddy features. Larger values in equivalent potential temperature (θE = 365   ∘K) were measured inside the hurricane boundary layer (HBL) over the WCE, where the vertical shear in horizontal currents (δV) remained stable and the ensuing cooling vertical mixing was negligible; smaller values in θE (355   ∘K) were measured over an oceanic frontal cyclone, where vertical mixing and upper-ocean cooling were more intense due to instability development in δV . Thus, correctly representing oceanic mesoscale eddy features in coupled numerical models is important to accurately reproduce oceanic responses to tropical cyclone forcing, as well as the contrasting thermodynamic forcing of the HBL that often causes storm intensity fluctuations over these warm oceanic regimes.

  1. Reanalysis of climate influences on Atlantic tropical cyclone activity using cluster analysis

    Science.gov (United States)

    Boudreault, Mathieu; Caron, Louis-Philippe; Camargo, Suzana J.

    2017-04-01

    We analyze, using Poisson regressions, the main climate influences on North Atlantic tropical cyclone activity. The analysis is performed using not only various time series of basin-wide storm counts but also various series of regional clusters, taking into account shortcomings of the hurricane database through estimates of missing storms. The analysis confirms that tropical cyclones forming in different regions of the Atlantic are susceptible to different climate influences. We also investigate the presence of trends in these various time series, both at the basin-wide and cluster levels, and show that, even after accounting for possible missing storms, there remains an upward trend in the eastern part of the basin and a downward trend in the western part. Using model selection algorithms, we show that the best model of Atlantic tropical cyclone activity for the recent past is constructed using Atlantic sea surface temperature and upper tropospheric temperature, while for the 1878-2015 period, the chosen covariates are Atlantic sea surface temperature and El Niño-Southern Oscillation. We also note that the presence of these artificial trends can impact the selection of the best covariates. If the underlying series shows an upward trend, then the mean Atlantic sea surface temperature captures both interannual variability and the upward trend, artificial or not. The relative sea surface temperature is chosen instead for stationary counts. Finally, we show that the predictive capability of the statistical models investigated is low for U.S. landfalling hurricanes but can be considerably improved when forecasting combinations of clusters whose hurricanes are most likely to make landfall.

  2. Rapid assessment tool for tropical cyclone waves and storm surge hazards in Mexico

    Science.gov (United States)

    Appendini, Christian M.; Rosengaus, Michel; Meza-Padilla, Rafael; Camacho-Magaña, Victor

    2017-04-01

    Mexico is under the constant threat of tropical cyclones generated in the Atlantic and the Eastern Pacific oceans. While the National Hurricane Center (NHC) in Miami is responsible for the forecast of tropical cyclones in both basins and providing watch and warning areas information for Mexico, Central America and the Caribbean, they are not responsible to issue waves and storm surge hazards. This work presents a quick assessment tool for waves and storm surge hazards developed under conditions that are common to developing countries: tight budget and time constraints, as well as limited numerical modeling capabilities. The system is based on 3100 synthetic tropical cyclones doing landfall in Mexico. Hydrodynamic and wave models were driven by the synthetic events to create a robust database composed of maximum envelops of wind speed, significant wave height and storm surge for each event. The results were incorporated into a forecast system that uses the NHC advisory to locate the synthetic events passing inside specified radiuses for the present and forecast position of the real event. Using limited computer resources, the system displays the information meeting the search criteria, and the forecaster can select specific events to generate the desired hazard map (i.e. wind, waves, and storm surge) based on the maximum envelop maps. This system was developed in a limited time frame to be operational in 2015 by the Hurricane and Severe Storms Unit of the Mexican National Weather Service, and represents a pilot project for other countries in the region not covered by detailed storm surge and waves forecasts.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  5. Mechanical Effect of Sea Spray on Tropical Cyclone Intensity and Orographic Effect on Aviation Turbulence

    Science.gov (United States)

    Villamil-Otero, Gian Alberto

    This dissertation consists of two topics, the impact of the mechanical effect of sea spray on tropical cyclone intensity, and the impact of orography on aviation turbulence. For the first research topic we study the mechanical effect of the ocean spray on idealized hurricane dynamics. Specifically, we have implemented the mathematical parameterization that describes the mechanical effect of the ocean spray into a numerical weather prediction code. The parameterization developed in our previous studies is based on the Monin-Obukhov Similarity (MOS) theory. The developed theoretical framework quantifies the decrease in turbulent intensity due to vertical spray stratification that causes the reduction in the surface friction, and, as a result, weakens the secondary circulation in a tropical cyclone. Numerical simulations of the idealized tropical cyclones with different sea spray production rates have demonstrated that the structural characteristics of the storm alter as the sea spray concentration increases. Specifically, the following changes have been observed: 1) increase in the tropical cyclone asymmetry, 2) longer development time of the hurricane, 3) outward displacement in the storm eyewall location, 4) decrease in the vertical extent of reflectivity, 5) reduction in the horizontal wind speeds, 6) decrease in the vertical motion and horizontal convergence of the hurricane, and 7) reduction of the total heat flux. For the second topic a thorough testing of the sponge layer depth is done to assess its effectiveness when using a real potential temperature profile in an idealized model such as CM1. The tests performed use a two-dimensional grid with a bell-shaped mountain of 2500 m high in a uniform flow of U=20 and 10 ms-1 with a potential temperature profile from the 2100 UTC 25 March 2006 Mobile GPS Advanced Upper-Air Sounding System (MGAUS) sounding upstream of the Sierra Nevada. The model top is specified at 35 km and the sponge layer depth is varied between

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

    Directory of Open Access Journals (Sweden)

    Kevin Reed

    2012-04-01

    Full Text Available 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

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

    Science.gov (United States)

    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

  8. Tropical Cyclone Track and Structure Sensitivity to Initialization in Idealized Simulations: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Yang Cao

    2011-01-01

    Full Text Available In the absence of environmental steering, tropical cyclone (TC motion largely reflects ¡§beta drift¡¨ owing to differential planetary vorticity advection by the storm¡¦s outer circulation. It is known that model physics choices (especially those relating to convection can significantly alter these outer winds and thus the storm track. Here, semi-idealized simulations are used to explore the influence of the initialization on subsequent vortex evolution and motion. Specifically, TCs bred from a buoyant ¡§bubble¡¨ are compared to bogussed vortices having a wide variety of parameterized shapes and sizes matching observations.

  9. Characteristics of the Nonoccurrence of Tropical Cyclones in the Western North Pacific in August 2014

    Directory of Open Access Journals (Sweden)

    Jae-Won Choi

    2016-10-01

    Full Text Available This study identified the causes of the nonoccurrence of tropical cyclones (TCs in August 2014 by examining large-scale environments. First, over the previous 30 years, the TC genesis frequency in August showed an overall statistically significant decline. In the tropical and subtropical western Pacific, the outgoing longwave radiation anomaly index also exhibited an overall increase until recently. Regarding precipitable water and precipitation, an analysis was performed on the difference between the mean values for August 2014 and the mean values for August over the previous 30 years. As a result, while convective activities were suppressed in the tropical and subtropical western Pacific, convective activities were strong in the mid-latitudes of East Asia. This indicates that while the western North Pacific summer monsoon was weakened in August 2014, the East Asian summer monsoon was strengthened. The weakening of the western North Pacific summer monsoon may have made it difficult for TCs to occur. An analysis of 850 hPa and 500 hPa stream flows showed the strengthening of anomalous huge anticyclonic circulations in the tropical and subtropical western Pacific, whereas anomalously cyclonic circulations were reinforced in the mid-latitudes of East Asia. This was associated with the result that the western North Pacific subtropical high (WNPSH showed further westward and southward expansion in August 2014 compared to the climatological mean WNPSH. Therefore, TCs were unlikely to occur in the tropical and subtropical western Pacific, but anomalous cold northerlies and anomalous warm southerlies converged in the Japanese Islands after originating in China’s central region and passing the East China Sea. Therefore, a favorable environment for the occurrence of precipitation had been formed.

  10. Impact assessment of coastal hazards due to future changes of tropical cyclones in the North Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Nobuhito Mori

    2016-03-01

    Full Text Available Tropical cyclones generate severe hazards in the middle latitudes. A brief review and applications of dynamical and statistical downscaling of tropical cyclone (TC are described targeting extreme storm surge and storm wave hazard assessment. First, a review of the current understanding of the changes in the characteristics of TCs in the past and in the future is shown. Then, a review and ongoing research about impact assessment of tropical cyclones both dynamical downscaling and statistical model are described for Typhoon Vera in 1959 and Typhoon Haiyan in 2013. Finally, several examples of impact assessment of storm surge and extreme wave changes are presented. Changes in both TC intensity and track are linked to future changes in extreme storm surge and wave climate in middle latitude.

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

    Science.gov (United States)

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

    2008-01-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. © 2012 by the Society for Academic Emergency Medicine.

  14. Possible connection between summer tropical cyclone frequency and spring Arctic Oscillation over East Asia

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ki-Seon [Korea Meteorological Administration, National Typhoon Center, Jeju (Korea, Republic of); Wu, Chun-Chieh [National Taiwan University, Department of Atmospheric Sciences, Taipei (China); Byun, Hi-Ryong [Pukyong National University, Department of Environmental Atmospheric Sciences, Busan (Korea, Republic of)

    2012-06-15

    This study shows that the frequency of summer tropical cyclones (TCs) in the areas of Japan, Korea, and Taiwan (JKT), which are located in the middle latitudes of East Asia, has a positive correlation with the Arctic Oscillation (AO) occurring during the preceding spring, while summer TC frequency in the Philippines (PH), located in the low latitudes, has a negative correlation with the AO of the preceding spring. During a positive AO phase, when the anomalous anticyclone forms over the mid-latitudes of East Asia, other anomalous cyclones develop not only in the high latitudes but also in the low latitudes from the preceding spring to the summer months. With this change, while southeasterlies in the JKT area derived from the mid-latitude anticyclone plays a role in steering TCs toward this area, northwesterlies strengthened in the PH area by the low-latitude cyclone plays a role in preventing TC movement toward this area. In addition, because of this pressure systems developed during this AO phase, TCs occur, move, and recurve in further northeastern part of the western North Pacific than they do during a negative AO phase. (orig.)

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

    Directory of Open Access Journals (Sweden)

    R. L. Sriver

    2013-01-01

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

  16. 'Electrically-Hot' Convection and Tropical Cyclone Development in the Eastern Atlantic

    Science.gov (United States)

    Leppert, Kenneth, II; Petersen, Walter A.; Williams, Earle

    2008-01-01

    The depth and intensity of convective-scale "hot" towers in intensifying tropical disturbances has been hypothesized to play a role in tropical cyclogenesis via dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this investigation we investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") resident in African Easterly Waves (AEW) may play in tropical cyclogenesis over the eastern Atlantic Ocean. NCEP reanalysis data for the months of July to November for the years 2004, 2006, and 2007 are analyzed for the domain of 5 N - 15 N and 500W - 300 E. Specifically, NCEP data for individual AEWs are partitioned into northerly, southerly, trough, and ridge phases using the 700 hPa meridional winds. Subsequently, information from National Hurricane Center storm reports were divided up into developing and non-developing waves (i.e. tropical cyclogenesis). Finally, composites were created of developing and non-developing waves using the NCEP variables, but with the inclusion of lightning flash count and infrared brightness temperature information. The Zeus and World Wide Lightning Location Network lightning data were used for the lightning information, and the IR brightness temperature data was extracted from the NASA global-merged infrared brightness temperature dataset.

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

    Science.gov (United States)

    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.

  18. Linkages of Remote Sea Surface Temperatures and Atlantic Tropical Cyclone Activity Mediated by the African Monsoon

    Energy Technology Data Exchange (ETDEWEB)

    Taraphdar, Sourav; Leung, Lai-Yung R.; Hagos, Samson M.

    2015-01-28

    Warm 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 show that the NAMED SST is linked to a strengthening of the Saharan heat low and enhancement of moisture and moist static energy in the lower atmosphere 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 (50W–20E; 10N–20N) of Atlantic TC. By modulating multiple processes associated with the African monsoon, this study demonstrates that warm NAMED SST explains 8% of interannual variability of Atlantic TC frequency. Thus NAME SST may provide useful predictability for Atlantic TC activity on seasonal-to-interannual time scale.

  19. Future Changes in Tropical Cyclone Activity in High-Resolution Large-Ensemble Simulations

    Science.gov (United States)

    Yoshida, Kohei; Sugi, Masato; Mizuta, Ryo; Murakami, Hiroyuki; Ishii, Masayoshi

    2017-10-01

    Projected future changes in global tropical cyclone (TC) activity are assessed using 5,000 year scale ensemble simulations for both current and 4 K surface warming climates with a 60 km global atmospheric model. The global number of TCs decreases by 33% in the future projection. Although geographical TC occurrences decrease generally, they increase in the central and eastern parts of the extra tropical North Pacific. Meanwhile, very intense (category 4 and 5) TC occurrences increase over a broader area including the south of Japan and south of Madagascar. The global number of category 4 and 5 TCs significantly decreases, contrary to the increase seen in several previous studies. Lifetime maximum surface wind speeds and precipitation rate are amplified globally. Regional TC activity changes have large uncertainty corresponding to sea surface temperature warming patterns. TC-resolving large-ensemble simulations provide useful information, especially for policy making related to future climate change.

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

    Science.gov (United States)

    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.

  1. The seasonally-varying influence of ENSO on rainfall and tropical cyclone activity in the Philippines

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Bradfield [The Earth Institute at Columbia University, International Research Institute for Climate and Society, Palisades, NY (United States); Camargo, Suzana J. [The Earth Institute at Columbia University, International Research Institute for Climate and Society, Palisades, NY (United States); Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY (United States)

    2009-01-15

    An observational study covering the period 1950-2002 examines a seasonal reversal in the ENSO rainfall signal in the north-central Philippines. In boreal summer of El Nino (La Nina) events, above (below) average rainfall typically occurs in this area. Rainfall anomalies of opposite sign develop across the country in the subsequent fall. This study investigates the seasonal evolution of the anomalous atmospheric circulation over the western North Pacific (WNP) during both El Nino and La Nina and places these features in the context of the large-scale evolution of ENSO events, including an analysis of changes in tropical cyclone activity affecting the Philippines. The results show that during boreal summer of El Nino (La Nina) events, a relatively narrow, zonally elongated band of enhanced (reduced) low-level westerlies develops across the WNP which serves to increase (decrease) the summer monsoon flow and moisture flux over the north-central Philippines and is associated with an increase (decrease) in the strength of the WNP monsoon trough via the anomalous relative vorticity. Tropical cyclone activity is shown to be enhanced (reduced) in the study region during boreal summer of El Nino (La Nina) events, which is related to the increase (decrease) of mid-level atmospheric moisture, as diagnosed using a genesis potential index. The subsequent evolution shows development of an anomalous anticyclone (cyclone) over the WNP in El Nino (La Nina) and the well-known tendency for below (above) average rainfall in the fall. Prolonged ENSO events also exhibit seasonal rainfall sign reversals in the Philippines with a similar evolution in atmospheric circulation. (orig.)

  2. Change in the tropical cyclone activity around Korea by the East Asian summer monsoon

    Science.gov (United States)

    Choi, Jae-Won; Cha, Yumi; Kim, Jeoung-Yun

    2017-12-01

    Correlation between the frequency of summer tropical cyclones (TCs) affecting Korea and the East Asian summer monsoon index (EASMI) was analyzed over the last 37 years. A clear positive correlation existed between the two variables, and this high positive correlation remained unchanged even when excluding El Niño-Southern Oscillation (ENSO) years. To investigate the causes of the positive correlation between the two variables in non-ENSO years, after the 8 years with the highest EASMI (high EASMI years) and the 8 years with the lowest EASMI (low EASMI years) were selected, and the average difference between the two phases was analyzed. In high EASMI years, in the difference between the two phases regarding 850 and 500 hPa streamline, anomalous cyclones were reinforced in the tropical and subtropical western North Pacific, while anomalous anticyclones were reinforced in mid-latitude East Asian areas. Due to these two anomalous pressure systems, anomalous southeasterlies developed near Korea, with these anomalous southeasterlies playing the role of anomalous steering flows making the TCs head toward areas near Korea. In addition, a monsoon trough strengthened more eastward, and TCs in high EASMI years occurred more in east ward over the western North Pacific.

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

    Science.gov (United States)

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

    2014-12-01

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

  4. An Intercomparison of GPS RO Retrievals with Colocated Analysis and In Situ Observations within Tropical Cyclones

    Directory of Open Access Journals (Sweden)

    Henry R. Winterbottom

    2010-01-01

    Full Text Available Observations from four Global Position System (GPS Radio Occultation (RO missions: Global Positioning System/Meteorology, CHAallenging Minisatellite Payload, Satellite de Aplicaciones Cientificas-C, and Constellation Observing System for Meteorology, Ionosphere and Climate and Taiwan's FORMOsa SATellite Mission #3 (COSMIC/FORMOSAT-3 are collected within a 600 km radius and ±180 minute temporal window of all observed tropical cyclones (TCs from 1995 to 2006 that were recorded in the global hurricane best-track reanalysis data set (Jarvinen et al. (1984; Davis et al. (1984. A composite analysis of tropical cyclone radial mean temperature and water vapor profiles is carried out using the GPS RO retrievals which are colocated with global analysis profiles and available in situ radiosonde observations. The differences between the respective observations and analysis profiles are quantified and the preliminary results show that the observations collected within TCs correspond favorably with both the analysis and radiosonde profiles which are colocated. It is concluded that GPS RO observations will contribute significantly to the understanding and modeling of TC structures, especially those related to vertical variability of the atmospheric state within TCs.

  5. Atlantic tropical cyclones water budget in observations and CNRM-CM5 model

    Science.gov (United States)

    Chauvin, Fabrice; Douville, Hervé; Ribes, Aurélien

    2017-12-01

    Water budgets in tropical cyclones (TCs) are computed in the ERA-interim (ERAI) re-analysis and the CNRM-CM5 model for the late 20th and 21st centuries. At a 6-hourly timescale and averaged over a 5° × 5° box around a TC center, the main contribution to rainfall is moisture convergence, with decreasing contribution of evaporation for increasing rainfall intensities. It is found that TC rainfall in ERAI and the model are underestimated when compared with the tropical rainfall measuring mission (TRMM), probably due to underestimated TC winds in ERAI vs. observed TCs. It is also found that relative increase in TC rainfall between the second half of the 20th and 21st centuries may surpass the rate of change suggested by the Clausius-Clapeyron formula. It may even reach twice this rate for reduced spatial domains corresponding to the highest cyclonic rainfall. This is in agreement with an expected positive feedback between TC rainfall intensity and dynamics.

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

    Science.gov (United States)

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

    2013-05-01

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

  7. An Intrathermocline Eddy and a tropical cyclone in the Bay of Bengal.

    Science.gov (United States)

    Gordon, Arnold L; Shroyer, Emily; Murty, V S N

    2017-04-12

    The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean eddies. On 5 December 2013 a sub-surface vortex or Intrathermocline Eddy (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface eddy from the eastern Bay of Bengal. While Lehar's interaction with the ocean initially removes heat from the upper layers of the eddy, air-sea flux is limited as the deeper portions of the eddy was subducted into the stratified thermocline, inhibiting further interaction with the atmosphere. The ITE core from 30 to 150 m is thus isolated from local air-sea fluxes by strong stratification at the mixed layer base, and its periphery is stable to shear instability, suggestive of longevity and the ability to carry water far distances with minimal modification.

  8. Simulated sensitivity of the tropical cyclone eyewall replacement cycle to the ambient temperature profile

    Science.gov (United States)

    Ma, Xulin; He, Jie; Ge, Xuyang

    2017-09-01

    In this study, the impacts of the environmental temperature profile on the tropical cyclone eyewall replacement cycle are examined using idealized numerical simulations. It is found that the environmental thermal condition can greatly affect the formation and structure of a secondary eyewall and the intensity change during the eyewall replacement cycle. Simulation with a warmer thermal profile produces a larger moat and a prolonged eyewall replacement cycle. It is revealed that the enhanced static stability greatly suppresses convection, and thus causes slow secondary eyewall formation. The possible processes influencing the decay of inner eyewall convection are investigated. It is revealed that the demise of the inner eyewall is related to a choking effect associated with outer eyewall convection, the radial distribution of moist entropy fluxes within the moat region, the enhanced static stability in the inner-core region, and the interaction between the inner and outer eyewalls due to the barotropic instability. This study motivates further research into how environmental conditions influence tropical cyclone dynamics and thermodynamics.

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

    Energy Technology Data Exchange (ETDEWEB)

    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."

  10. A numerical study of the role of the vertical structure of vorticity during tropical cyclone genesis

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, T N [Flosolver Unit, National Aerospace Laboratories, PO Box 1779, Bangalore 560017 (India); Mathew, Joseph, E-mail: tnv@flosolver.nal.res.i, E-mail: joseph@aero.iisc.ernet.i [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2010-08-15

    An eight-level axisymmetric model with simple parameterizations for clouds and the atmospheric boundary layer was developed to examine the evolution of vortices that are precursors to tropical cyclones. The effect of vertical distributions of vorticity, especially that arising from a merger of mid-level vortices, was studied by us to provide support for a new vortex-merger theory of tropical cyclone genesis. The basic model was validated with the analytical results available for the spin-down of axisymmetric vortices. With the inclusion of the cloud and boundary layer parameterizations, the evolution of deep vortices into hurricanes and the subsequent decay are simulated quite well. The effects of several parameters such as the initial vortex strength, radius of maximum winds, sea-surface temperature and latitude (Coriolis parameter) on the evolution were examined. A new finding is the manner in which mid-level vortices of the same strength decay and how, on simulated merger of these mid-level vortices, the resulting vortex amplifies to hurricane strength in a realistic time frame. The importance of sea-surface temperature on the evolution of full vortices was studied and explained. Also it was found that the strength of the surface vortex determines the time taken by the deep vortex to amplify to hurricane strength.

  11. Synoptic-Scale Precursors to Tropical Cyclone Rapid Intensification in the Atlantic Basin

    Directory of Open Access Journals (Sweden)

    Alexandria Grimes

    2015-01-01

    Full Text Available Forecasting rapid intensification (hereafter referred to as RI of tropical cyclones in the Atlantic Basin is still a challenge due to a limited understanding of the meteorological processes that are necessary for predicting RI. To address this challenge, this study considered large-scale processes as RI indicators within tropical cyclone environments. The large-scale processes were identified by formulating composite map types of RI and non-RI storms using NASA MERRA data from 1979 to 2009. The composite fields were formulated by a blended RPCA and cluster analysis approach, yielding multiple map types of RI’s and non-RI’s. Additionally, statistical differences in the large-scale processes were identified by formulating permutation tests, based on the composite output, revealing variables that were statistically significantly distinct between RI and non-RI storms. These variables were used as input in two prediction schemes: logistic regression and support vector machine classification. Ultimately, the approach identified midlevel vorticity, pressure vertical velocity, 200–850 hPa vertical shear, low-level potential temperature, and specific humidity as the most significant in diagnosing RI, yielding modest skill in identifying RI storms.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    Krasilnikov, E.

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

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

    Science.gov (United States)

    Slocum, Christopher J.

    Tropical cyclone intensity forecasting skill has slowed in improvement for both dynamical and statistical-dynamical forecasting methods in comparison to gains seen in track forecasting skill. Also, forecast skill related to rapid intensification, e.g. a 30 kt or greater increase in intensity within a 24-hour period, still remains poor. In order to make advances and gain a greater understanding, the processes that affect intensity change, especially rapid intensification, need further study. This work evaluates the roles of diabatic and frictional forcing on the structure and intensity of tropical cyclones. To assess the diabatic forcing effects on intensity change in tropical cyclones, this study develops applications of Eliassen's balanced vortex model to obtain one-dimensional solutions to the geopotential tendency and two-dimensional solutions to the transverse circulation. The one-dimensional balanced solutions are found with dynamical model outputs as well as aircraft reconnaissance combined with diabatic heating derived from microwave rainfall rate retrievals. This work uses solutions from both datasets to make short-range intensity predictions. The results show that for the one-dimensional solutions, the tangential tendency does not match the dynamical model or aircraft wind tendencies. To relax the assumptions of the one-dimensional solutions to the geopotential tendency, solutions for idealized vortices are examined by finding two-dimensional solutions to the transverse circulation. The two-dimensional solutions allow for evaluation of the axisymmetric structure of the vortex on the (r, z)-plane without setting the baroclinicity to zero and the static stability to a constant value. While the sensitivity of tangential wind tendency to diabatic forcing and the region of high inertial stability is more realistic in the two-dimensional results, the solutions still neglect the influence of friction from the boundary layer. To understand further the role of

  15. Tropical-Like Cyclones in the Mediterranean: The case of Medicane "Qendresa" in 2014

    Science.gov (United States)

    Patlakas, P.; Nenes, A.; Nikolopoulos, E. I.; Kallos, G. B.

    2016-12-01

    Intense storm characteristics and structure that resemble hurricanes can periodically form over the Mediterranean Sea. These so-called Medicanes form in a similar fashion to tropical cyclones, despite the different climatic characteristics between the Mediterranean Sea and the tropical oceans. Unlike their tropical counterparts, Medicanes are poorly understood and studied. The recurrence interval of such extreme conditions is lower than tropical cyclones, but they can cause significant damages to property and pose threat to human lives. The frequency and intensity of Medicanes, in response to climate change, is also completely unknown. One recent event is the case of Medicane "Qendresa" that took place during 7-8 November 2014. It was generated in the maritime area between Italy and Tunisia and dissipated within about 48 hours. Winds and wind gusts reached 111 km/h and 154 km/h respectively, while the lowest recorded pressure reached the value of 978.6 hPa. At the same time, a 24h accumulated precipitation of more than 100 mm was recorded in the SE part of Sicily during the second day of the event. The contact of the system with Sicily and the exhibited stationarity caused the large amounts of precipitating water over the island. The quick dissipation can be attributed to the relatively quick landfall that severely reduced latent heat supply from the warm sea surface. The formation of a cyclone was forecasted by the most of operational models but its characteristics deviated significantly. In this study we utilize a state-of-the-art atmospheric model, the RAMS-ICLAMS Modeling System, to simulate the full lifecycle of the storm and study in detail the underlying mechanisms associated with the initiation, intensification and dissipation of the system. A series of sensitivity simulations define the key drivers behind the formation and development of Medicanes. The simulations revealed the high sensitivity of these systems to different dynamical and microphysical

  16. Development of a PBL Parameterization Scheme for the Tropical Cyclone Model and an Improved Magnetospheric Model for Magic.

    Science.gov (United States)

    1981-03-25

    AD-AO98 635 .JAYCOR ALEXANDRIA VA F/6 4/2 DEVELOPMENTO A PBL PARAMETERIZATION SCHEME FOR THE TROPICAL C--ETC(U) MAR al S A CHANG. C AGRITELLIS...PERIOD COVERED Final Report DEVELOPMENT OF A PBL PARAMETERIZATION SCHEME 9/07/79 - 9/08/80 FOR THE TROPICAL CYCLONE MODEL AND AN IMPROVED G. PERFORMING...dimensional, multi-layer PBL model, the GST parameterization yields accurate moisture fluxes, but slightly over- estimates the momentum flux and

  17. Global representation of tropical cyclone-induced ocean thermal changes using Argo data – Part 1: Methods and results

    OpenAIRE

    Cheng, L; Zhu, J.; Sriver, R. L.

    2014-01-01

    Argo floats are used to examine tropical cyclone (TC)-induced ocean thermal changes on the global scale by comparing temperature profiles before and after TC passage. We present a footprint method that analyzes cross-track thermal responses along all storm tracks during the period 2004–2012. We combine the results into composite representations of the vertical structure of the average thermal response for two different categories: tropical storms/depressions ...

  18. Seismic monitoring of the bedload transport in La Réunion Island rivers during tropical cyclones

    Science.gov (United States)

    Gonzalez, Alicia; Fontaine, Fabrice. R.; Burtin, Arnaud; Barruol, Guilhem; Recking, Alain; Join, Jean-Lambert; Delcher, Eric

    2017-04-01

    La Réunion Island, located in the western Indian Ocean, undergoes heavy annual precipitations during the rainy season (Dec to Apr) and particularly during tropical depressions and cyclones. Large rainfalls that affect this volcanic island modify the stream dynamic and control the sediment transport and the very active erosion. However, in situ characterization of sediment transport is difficult during high water stage, requiring indirect observation such as seismic noise. In order to monitor spatial and temporal variations of the river's bed-load during tropical cyclones from the high-frequency seismic noise in La Réunion, we deployed a temporary seismic network of 9 three-component broadband seismometers along two rivers: Rivière des Pluies and Rivière du Mât, both located on the northern side of the island. Seismic data are supplemented by meteorological and hydrological stations installed in these experimental watersheds. They provide valuable data such as precipitations, water discharge and water level. We also characterized the stream morphology and the bed surface grain size distribution to set the current characteristics and we aim to repeat this analyze after each flood event in order to quantify the effect of the flood episode on the sediment transport. We present the results of the signature of the cyclone Bejisa which passed close to the island in January 2014 recorded at three broadband seismic stations, among which two are located near instrumented streams: station SALA installed close to the Rivière du Mât and the permanent GEOSCOPE seismic station RER installed in a 4.7 km long tunnel close to the Rivière de l'Est. The third station MAID is used as a reference station since it is located on a summit (2.190 km altitude) and far from any active river. We observe a significant increase of the precipitation as the cyclone eye was at 300 km to the island and the associated increase of the water discharge clearly generates a sudden increase of the

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2009-01-01

    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.

  1. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period

    Science.gov (United States)

    Pausata, Francesco S. R.; Emanuel, Kerry A.; Chiacchio, Marc; Diro, Gulilat T.; Zhang, Qiong; Sushama, Laxmi; Stager, J. Curt; Donnelly, Jeffrey P.

    2017-06-01

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  2. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period.

    Science.gov (United States)

    Pausata, Francesco S R; Emanuel, Kerry A; Chiacchio, Marc; Diro, Gulilat T; Zhang, Qiong; Sushama, Laxmi; Stager, J Curt; Donnelly, Jeffrey P

    2017-06-13

    Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate.

  3. Influence of Tropical Cyclones Period 1970 TO 2010 IN the Region of Bahia de Banderas, Nayarit-Jalisco Mexico

    Science.gov (United States)

    Hernandez, J. M.

    2013-12-01

    This study evaluates the impacts of tropical cyclones (TC) that made landfall in populated areas along the Pacific coast of Mexico, especially in the region of Bahia de Banderas. During the period of 1970-2010 and used a database of international natural disasters to identify impacts. Were more than 13 events during the reporting period, of which 10 are examined more precipitation accumulated and 6 that caused further damage to the affected population in these cases ranged from 5000 to more than 15 000 inhabitants. Strong winds and heavy rainfall in periods of one to three days were associated with property damage and loss of life. The results of the study indicate that excessive accumulations of rain and daily intensity are important factors connected with the occurrence of disasters in densely populated areas. Six of the first 10 Tropical Cyclone associated with major disasters occurred in conditions of El Niño and four neutral conditions. With the analysis of satellite images using GOES-10 in the IDV software maps were obtained in the coastal impacts of Banderas Bay and describes the main features of each meteorological phenomena. In which concludes that no tropical cyclone entered directly to the Banderas Bay region, but its effects were very relevant, taking into account the topography, land use change and the vulnerability of the region. Tropical Cyclones that have affected the region of Bay of Banderas

  4. Comparison of Explicitly Simulated and Downscaled Tropical Cyclone Activity in a High-Resolution Global Climate Model

    Directory of Open Access Journals (Sweden)

    Hirofumi Tomita

    2010-01-01

    Full Text Available The response of tropical cyclone activity to climate change is a matter of great inherent interest and practical importance. Most current global climate models are not, however, capable of adequately resolving tropical cyclones; this has led to the development of downscaling techniques designed to infer tropical cyclone activity from the large-scale fields produced by climate models. Here we compare the statistics of tropical cyclones simulated explicitly in a very high resolution (~14 km grid mesh global climate model to the results of one such downscaling technique driven by the same global model. This is done for a simulation of the current climate and also for a simulation of a climate warmed by the addition of carbon dioxide. The explicitly simulated and downscaled storms are similarly distributed in space, but the intensity distribution of the downscaled events has a somewhat longer high-intensity tail, owing to the higher resolution of the downscaling model. Both explicitly simulated and downscaled events show large increases in the frequency of events at the high-intensity ends of their respective intensity distributions, but the downscaled storms also show increases in low-intensity events, whereas the explicitly simulated weaker events decline in number. On the regional scale, there are large differences in the responses of the explicitly simulated and downscaled events to global warming. In particular, the power dissipation of downscaled events shows a 175% increase in the Atlantic, while the power dissipation of explicitly simulated events declines there.

  5. Breaching vulnerability of coastal barriers under effects of tropical cyclones : A model study on the Hue lagoon - Vietnam

    NARCIS (Netherlands)

    Tuan, T.Q.; Stive, M.J.F.; Verhagen, H.J.

    2006-01-01

    Under effects of tropical cyclones, the coast is subjected to attack both by surge and wave from the sea and by flooding from the bay. These forces pose a serious breaching threat to natural sea-defence works such as barrier spits, barrier islands, lagoon barriers, etc. on the coast. Unintended

  6. Thermodynamics of a tropical cyclone: generation and dissipation of mechanical energy in a self-driven convection system

    Directory of Open Access Journals (Sweden)

    Hisashi Ozawa

    2015-01-01

    Full Text Available The formation process of circulatory motion of a tropical cyclone is investigated from a thermodynamic viewpoint. The generation rate of mechanical energy by a fluid motion under diabatic heating and cooling, and the dissipation rate of this energy due to irreversible processes are formulated from the first and second laws of thermodynamics. This formulation is applied to a tropical cyclone, and the formation process of the circulatory motion is examined from a balance between the generation and dissipation rates of mechanical energy in the fluid system. We find from this formulation and data analysis that the thermodynamic efficiency of tropical cyclones is about 40% lower than the Carnot maximum efficiency because of the presence of thermal dissipation due to irreversible transport of sensible and latent heat in the atmosphere. We show that a tropical cyclone tends to develop within a few days through a feedback supply of mechanical energy when the sea surface temperature is higher than 300 K, and when the horizontal scale of circulation becomes larger than the vertical height of the troposphere. This result is consistent with the critical radius of 50 km and the corresponding central pressure of about 995 hPa found in statistical properties of typhoons observed in the western North Pacific.

  7. A study on raindrop size distribution variability in before and after landfall precipitations of tropical cyclones observed over southern India

    Science.gov (United States)

    Janapati, Jayalakshmi; seela, Balaji Kumar; Reddy M., Venkatrami; Reddy K., Krishna; Lin, Pay-Liam; Rao T., Narayana; Liu, Chian-Yi

    2017-06-01

    Raindrop size distribution (RSD) characteristics in before landfall (BLF) and after landfall (ALF) of three tropical cyclones (JAL, THANE, and NILAM) induced precipitations are investigated by using a laser-based (PARticleSIze and VELocity - PARSIVEL) disdrometer at two different locations [Kadapa (14.47°N, 78.82°E) and Gadanki (13.5°N, 79.2°E)] in semi-arid region of southern India. In both BLF and ALF precipitations of these three cyclones, convective precipitations have higher mass weighted mean diameter (Dm) and lower normalized intercept parameter (log10Nw) values than stratiform precipitations. The radar reflectivity (Z) and rain rate (R) relations (Z=A*Rb) showed distinct variations in BLF and ALF precipitations of three cyclones. BLF precipitation of JAL cyclone has a higher Dm than ALF precipitation. Whereas, for THANE and NILAM cyclones ALF precipitations have higher Dm than BLF. The Dm values of three cyclones (both in BLF and ALF) are smaller than the Dm values of the other (Atlantic and Pacific) oceanic cyclones. Interaction of different regions (eyewall, inner rainbands, and outer rainbands) of cyclones with the environment and underlying surface led to RSD variations between BLF and ALF precipitations through different microphysical (collision-coalescence, breakup, evaporation, and riming) processes. The immediate significance of the present work is that (i) it contributes to our understanding of cyclone RSD in BLF and ALF precipitations, and (ii) it provides the useful information for quantitative estimation of rainfall from Doppler weather radar observations.

  8. Assessing the Uncertainty of Tropical Cyclone Simulations in NCAR's Community Atmosphere Model

    Directory of Open Access Journals (Sweden)

    Kevin A Reed

    2011-08-01

    Full Text Available The paper explores the impact of the initial-data, parameter and structural model uncertainty on the simulation of a tropical cyclone-like vortex in the National Center for Atmospheric Research's (NCAR Community Atmosphere Model (CAM. An analytic technique is used to initialize the model with an idealized weak vortex that develops into a tropical cyclone over ten simulation days. A total of 78 ensemble simulations are performed at horizontal grid spacings of 1.0°, 0.5° and 0.25° using two recently released versions of the model, CAM 4 and CAM 5. The ensemble members represent simulations with random small-amplitude perturbations of the initial conditions, small shifts in the longitudinal position of the initial vortex and runs with slightly altered model parameters. The main distinction between CAM 4 and CAM 5 lies within the physical parameterization suite, and the simulations with both CAM versions at the varying resolutions assess the structural model uncertainty. At all resolutions storms are produced with many tropical cyclone-like characteristics. The CAM 5 simulations exhibit more intense storms than CAM 4 by day 10 at the 0.5° and 0.25° grid spacings, while the CAM 4 storm at 1.0° is stronger. There are also distinct differences in the shapes and vertical profiles of the storms in the two variants of CAM. The ensemble members show no distinction between the initial-data and parameter uncertainty simulations. At day 10 they produce ensemble root-mean-square deviations from an unperturbed control simulation on the order of 1--5 m s-1 for the maximum low-level wind speed and 2--10 hPa for the minimum surface pressure. However, there are large differences between the two CAM versions at identical horizontal resolutions. It suggests that the structural uncertainty is more dominant than the initial-data and parameter uncertainties in this study. The uncertainty among the ensemble members is assessed and quantified.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  10. Management van World-Wide Web Servers

    NARCIS (Netherlands)

    van Hengstum, F.P.H.; Pras, Aiko

    1996-01-01

    Het World Wide Web is een populaire Internet toepassing waarmee het mogelijk is documenten aan willekeurige Internet gebruikers aan te bieden. Omdat hiervoor nog geen voorzieningen zijn getroffen, was het tot voor kort niet goed mogelijk het World Wide Web op afstand te beheren. De Universiteit

  11. Innovation in Science Education - World-Wide.

    Science.gov (United States)

    Baez, Albert V.

    The purpose of this book is to promote improvements in science education, world-wide, but particularly in developing countries. It is addressed to those in positions to make effective contributions to the improvement of science education. The world-wide role of science education, the goals of innovative activities, past experience in efforts to…

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

    Science.gov (United States)

    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

  13. Consistency in the World Wide Web

    DEFF Research Database (Denmark)

    Thomsen, Jakob Grauenkjær

    Tim Berners-Lee envisioned that computers will behave as agents of humans on the World Wide Web, where they will retrieve, extract, and interact with information from the World Wide Web. A step towards this vision is to make computers capable of extracting this information in a reliable...... and consistent way. In this dissertation we study steps towards this vision by showing techniques for the specication, the verication and the evaluation of the consistency of information in the World Wide Web. We show how to detect certain classes of errors in a specication of information, and we show how...... the World Wide Web, in order to help perform consistent evaluations of web extraction techniques. These contributions are steps towards having computers reliable and consistently extract information from the World Wide Web, which in turn are steps towards achieving Tim Berners-Lee's vision. ii...

  14. Subseasonal shift in tropical cyclone genesis over the western North Pacific in 2013

    Science.gov (United States)

    Choi, Yumi; Ha, Kyung-Ja

    2017-09-01

    The 2013 subseasonal asymmetry in tropical cyclone (TC) genesis over the western North Pacific (WNP) was investigated by using the 1979-2013 RSMC best track dataset. The genesis frequency of the 2013 WNP TCs between June-August (summer) and September-November (fall) manifested an abnormal temporal asymmetry: fewer typhoons (more tropical storms) in summer and more typhoons (normal tropical storms) in fall. The 2013 active summer-tropical storm genesis arose from both a failure of eastward extension of monsoon confluence region, especially in August and a lack of moisture supply for TC genesis over the eastern part of WNP, and consequently from fewer probability to reach typhoon intensity due to the westward movement of favorable location for genesis. Thereafter, the eastward extension of monsoon shear line in September and the establishment of monsoon gyre in October induced the eastward movement of favorable location for genesis which increased probability to reach typhoon intensity. The relative contribution of mid-level relative humidity to the positive GPI change played a major role in favorable condition for typhoon genesis in September (45.2%) and October (50.9%). The monsoon gyre pattern played a leading role in the most active fall-typhoon in 2013 contributing to the highest number of October-typhoon. The eastward-migration of convection mainly contributed to the subseasonal shift of TC genesis location following eastward movement of local SST warming from summer to fall under the La Nina-like neutral state. The enhanced active boreal summer intraseasonal oscillation (BSISO) in fall provided more favorable conditions for TC genesis showing about twice as many TCs occurred regarding BSISO in fall than those in summer. This spatiotemporal asymmetry in the large-scale circulations and moisture conditions between summer and fall accounted for the subseasonal shift of genesis location of TCs, and consequently for the active summer-tropical storm genesis and the

  15. Statistical Relationships Between the Subtropical Jet Stream and Extra-tropical Cyclones

    Science.gov (United States)

    LIU, J.; Chiang, J. C. H.; Prabhat, M.; Loring, B.; Muszynski, G.

    2016-12-01

    Extra-tropical cyclones(ETCs) and associated fronts bring much of the precipitation in California during winter. It was previously suggested that inter-model spread of the California precipitation in future projection under global warming could be largely explained by the inter-model spread of ETC activities, with a correlation of 0.85. ETCs are believed to be steered by the jet stream, but a definitive relationship between the frontal precipitation in California and the subtropical jet through cyclone activities is yet to be established . Using output from CCSM4 historical and future runs, we investigate how California precipitation changes are tied to changes in ETC characteristics, and how the jet stream in turn influence the ETCs. The strength, the latitudinal position, the width of the jet stream are studied against the spatial distribution and the life span of the ETCs. We utilize the parallel toolkit for extreme climate analysis (TECA) to track both the jet stream and the ETCs and to analyze statistics relating the two. We rigorously define ETCs by its pressure, vorticity, and preferable direction of travel, and also track the jet stream in the 3-D space by its wind speed and westerly component. This study brings new insights into the dynamic relationship between midlatitude storm tracks and the jet stream.

  16. A Statistical Approach For Modeling Tropical Cyclones. Synthetic Hurricanes Generator Model

    Energy Technology Data Exchange (ETDEWEB)

    Pasqualini, Donatella [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-11

    This manuscript brie y describes a statistical ap- proach to generate synthetic tropical cyclone tracks to be used in risk evaluations. The Synthetic Hur- ricane Generator (SynHurG) model allows model- ing hurricane risk in the United States supporting decision makers and implementations of adaptation strategies to extreme weather. In the literature there are mainly two approaches to model hurricane hazard for risk prediction: deterministic-statistical approaches, where the storm key physical parameters are calculated using physi- cal complex climate models and the tracks are usually determined statistically from historical data; and sta- tistical approaches, where both variables and tracks are estimated stochastically using historical records. SynHurG falls in the second category adopting a pure stochastic approach.

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Impact of aerosols on tropical cyclone-induced precipitation over mainland China

    Science.gov (United States)

    Zhou, Lijing; Yang, Xin

    2017-04-01

    In this paper, the impacts of aerosols on Tropical Cyclone (TC) precipitation over mainland China during 1980-2014 were investigated. The TC induced precipitation is objectively indentified based on Western North Pacific (WNP) TC historical track and daily precipitation from meteorological stations. Aerosol optical depth (AOD) from the Second Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) is used to represent the amount of aerosol pollution. The interdecadal and interannual variations of aerosol optical depth (AOD) and TC precipitation were analyzed over the past 35 years. The downward trend are found in the annual numbers of TCs that affect China, but there is an increase in the average number of rain days per TC per year. Meanwhile, the upward trends in the TC daily precipitation are accompanied with the increases in the AOD on average. These variations in TC precipitation is most likely associated with aerosol indirect effects.

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

    Science.gov (United States)

    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.; hide

    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.

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

    Science.gov (United States)

    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; hide

    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.

  1. Dynamic Potential Intensity: An improved representation of the ocean’s impact on tropical cyclones

    Energy Technology Data Exchange (ETDEWEB)

    Balaguru, Karthik; Foltz, Gregory R.; Leung, Ruby L.; D' Asaro, Eric; Emanuel, Kerry A.; Liu, Hailong; Zedler, Sarah E.

    2015-08-18

    To incorporate the effects of tropical cyclone (TC)-induced upper ocean mixing and sea surface temperature (SST) cooling on TC intensification, a vertical average of temperature down to a fixed depth was proposed as a replacement for SST within the framework of air-sea coupled Potential Intensity (PI). However, the depth to which TC-induced mixing penetrates may vary substantially with ocean stratification and storm state. To account for these effects, here we develop a “Dynamic Potential Intensity” (DPI) based on considerations of stratified fluid turbulence. For the Argo period 2004–2013 and the three major TC basins of the Northern Hemisphere, we show that the DPI explains 11–32% of the variance in TC intensification, compared to 0–16% using previous methods. The improvement obtained using the DPI is particularly large in the eastern Pacific where the thermocline is shallow and ocean stratification effects are strong.

  2. Variations in tropical cyclone-related discharge in four watersheds near Houston, Texas

    Directory of Open Access Journals (Sweden)

    Laiyin Zhu

    2015-01-01

    Full Text Available We examined a 60-year record of daily precipitation and river discharge related to tropical cyclones (TCs in four watersheds undergoing land use and land cover change near Houston, Texas. Results show that TCs are responsible for ∼20% of the annual maximum discharge events in the four selected watersheds. Although there are no trends in TC precipitation, increasing trends were observed in daily extreme discharge and TC-related discharge. The more developed watersheds (Whiteoak Bayou and Brays Bayou, tend to have higher extreme discharge and steeper trends in extreme discharge than the less developed watersheds (Cypress Creek. Increases in TC-related extreme discharges correspond with increases in developed land and decreases in vegetated land between 1980 and 2006. Therefore, changes in land cover/use in watersheds near Houston are a major cause of the increased flooding risk in recent years.

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

    Science.gov (United States)

    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.

  4. On the variability of projected tropical cyclone genesis in GCM ensembles

    Directory of Open Access Journals (Sweden)

    M. Chattopadhyay

    2012-05-01

    Full Text Available The development of projections for changes in the genesis of tropical cyclones (TCs for a changed climate is explored in this article using outputs from the Coupled Model Intercomparison Project: Phase 3 (CMIP3 models. In this study, we explore how the projected change in the genesis frequency of TCs strongly depends upon the selection of models used in the ensemble. Results from 16 CMIP3 models are analysed and validated against the National Center for Environmental Prediction (NCEP and European Centre for Medium Range Weather forecast re-analysis at 40 km (ERA40 reanalysis and an ensemble mean of TC genesis diagnostics is calculated using the CMIP3 models. The response of these models to a future climate using the IPCC A2 scenario is also studied in the context of selecting models to calculate an ensemble mean.

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

    Directory of Open Access Journals (Sweden)

    Paul Tchounwou

    2010-04-01

    Full Text Available 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.

  6. Tropical Cyclones Wind Measurements with the SMAP L-Band Radiometer

    Science.gov (United States)

    Ricciardulli, L.; Meissner, T.; Wentz, F. J.

    2016-12-01

    The Soil Moisture Active Passive Mission SMAP was launched in January 2015 and has been providing science data since April 2015. Though designed to measure soil moisture, the SMAP radiometer has an excellent capability to measure ocean winds in tropical cyclones at a resolution of 40 km, with a swath width of 1000 km. The L-band radiometer V-pol and H-pol channels keep very good sensitivity to ocean surface wind speed even at very high wind speeds and they are only little impacted by rain. We briefly discuss the major features of the SMAP sensor, the geophysical model function that is used in the ocean vector wind retrieval and the basic steps of the retrieval algorithm. We will then illustrate the capability of this instrument to observe very high surface winds by comparing them to other validation datasets. The most important validation source is NOAA's airborne Step Frequency Microwave Radiometer SFMR, whose wind speeds were collocated with SMAP in space and time and resampled to the SMAP resolution. A comparison between SMAP and SFMR winds in hurricanes of the 2015 season, including Patricia, shows excellent correlation over a wide wind speed range (15 - 70 m/s) and no degradation in rain. This agreement is unique and gives SMAP a distinct advantage over many other space-borne sensors such as C-band or Ku-band scatterometers or radiometers, which either lose sensitivity at very high winds or degrade in rainy conditions. We will analyze the SMAP surface winds during the full evolution of the storms in recent intense tropical cyclones (Patricia, Winston, Fantala, and Nepartak) and compare them with wind measurements from ASCAT, RapidScat, and WindSat, with the NCEP wind fields, and with the best track data from the Joint Typhoon Warning Center.The SMAP wind data are available as twice-daily 0.25 deg gridded maps at www.remss.com.

  7. Detection and Tracking of Tropical Cyclones on a Seasonal Scale in the Philippines

    Directory of Open Access Journals (Sweden)

    Josefina C. Argete

    2007-12-01

    Full Text Available A regional climate model is used to detect tropical cyclones (TC and simulate their tracks for a four-month (June-July-August-September wet season in the Philippine region. The model, run at 45-km resolution, is forced along the boundaries with 6-hourly reanalyses data (ERA-40 with about 250-km resolution. Three experiments are devised which varied the size of the domain and placement of the boundaries.A detection and tracking algorithm is developed using 850-mb vorticity threshold, minimum sea level pressure and the presence of a warm core aloft as criteria. The tracks extracted from the ERA-40 field, herein called analyses track, are compared with JTWC best track to test the performance of the tracking algorithm. Of the fourteen (14 TC that entered the domain, ten were formed in the Pacific Ocean and four in the South China Sea. The algorithm detected all TC and skillfully captured the JTWC best track. From the 417 cases (6-hourly positions of the 14 TC, the mean zonal and meridional errors are -164, -23 km, respectively, where the analyses tracks are on the average moving faster westward and southward than the best track. The relatively small magnitude of errors indicates skill of the tracking method.The regional model is able to detect all 14 TC but with tracks that are farther displaced north of analyses. Simulation of track was enhanced as domain size is decreased. The intensity simulation is improved as more typhoons otherwise not found in the forcing data are generated by the regional model. This study demonstrates that a regional model forced by "perfect" boundary conditions can reasonably simulate the tracks and intensity of tropical cyclones on a seasonal scale. The importance of the use of the proper domain configuration is also shown.

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

    Directory of Open Access Journals (Sweden)

    Roger Beeden

    Full Text Available 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.

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

    Science.gov (United States)

    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).

  10. Investigating Sensitivity to Saharan Dust in Tropical Cyclone Formation Using Nasa's Adjoint Model

    Science.gov (United States)

    Holdaway, Daniel

    2015-01-01

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

  11. The World Wide Web of War

    National Research Council Canada - National Science Library

    Smith, Craig A

    2006-01-01

    Modern communications, combined with the near instantaneous publication of information on the World Wide Web, are providing the means to dramatically affect the pursuit, conduct, and public opinion of war on both sides...

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

    Science.gov (United States)

    Putman, William M.

    2010-01-01

    One of the primary interests of Global Change research is the impact of climate changes and climate variability on extreme weather events, such as intense tropical storms and hurricanes. Atmospheric climate models run at resolutions of global weather models have been used to study the impact of climate variability, as seen in sea surface temperatures, on the frequency and intensity of tropical cyclones. NASA's Goddard Earth Observing System Model, version 5 (GEOS-5) in ensembles run at 50 km resolution has been able to reproduce the interannual variations of tropical cyclone frequency seen in nature. This, and other global models, have found it much more difficult to reproduce the interannual changes in intensity, a result that reflects the inability of the models to simulate the intensities of the most extreme storms. Better representation of the structures of cyclones requires much higher resolution models. Such improved representation is also fundamental to making best use of satellite observations. In collaboration with NOAA's Geophysical Fluid Dynamics Laboratory, GEOS-5 now has the capability of running at much higher resolution to better represent cloud-scale resolutions. Global simulations at cloud-permitting resolutions (10- to 3.5-km) allows for the development of realistic tropical cyclones from tropical storm 119 km/hr winds) to category 5 (>249km1hr winds) intensities. GEOS-5 has produced realistic rain-band and eye-wall structures in tropical cyclones that can be directly analyzed against satellite observations. For the first time a global climate model is capable of representing realistic intensity and track variability on a seasonal scale across basins. GEOS-5 is also used in assimilation mode to test the impact of NASA's observations on tropical cyclone forecasts. One such test, for tropical cyclone Nargis in the Indian Ocean in May 2008, showed that observations from Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit

  13. Emergency Medicine for medical students world wide!

    DEFF Research Database (Denmark)

    Perinpam, Larshan; Thi Huynh, Anh-Nhi

    2015-01-01

    A guest blog from Larshan Perinpam (President of ISAEM) and Anh-Nhi Thi Huynh (Vice president of external affairs, ISAEM) - http://blogs.bmj.com/emj/2015/04/17/emergency-medicine-for-medical-students-world-wide/......A guest blog from Larshan Perinpam (President of ISAEM) and Anh-Nhi Thi Huynh (Vice president of external affairs, ISAEM) - http://blogs.bmj.com/emj/2015/04/17/emergency-medicine-for-medical-students-world-wide/...

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

    Science.gov (United States)

    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.

  15. Tropical cyclones in the Bay of Bengal and extreme sea-level projections along the east coast of India in a future climate scenario

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.; RameshKumar, M.R.; Sindhu, B.

    , Dubai, UAE The simulations from the regional climate model, PRECIS (Providing REgional Climates for Impacts Studies), were analysed for the occurrence of tropical cyclones in the Bay of Bengal in a baseline scenario (1961–1990) and a future...

  16. Southern Hemisphere Application of the Systematic Approach to Tropical Cyclone Forecasting Part 4: Sources of Large Track Errors by Dynamical Models

    National Research Council Canada - National Science Library

    Reader, Grahame

    2000-01-01

    Sources of 72-h track errors > 300 n mi by four dynamical model tropical cyclone predictions in the Southern Hemisphere during the 1997-98 and 1998-99 seasons are studied using conceptual models Carr and Elsberry have previously...

  17. Potential impacts of assimilating all‐sky infrared satellite radiances from GOES‐R on convection‐permitting analysis and prediction of tropical cyclones

    National Research Council Canada - National Science Library

    Zhang, Fuqing; Minamide, Masashi; Clothiaux, Eugene E

    2016-01-01

    The potential impacts of GOES‐R satellite radiances on tropical cyclone analysis and prediction were examined through ensemble correlations between simulated infrared brightness temperatures and various model state variables...

  18. Historical North Atlantic Tropical Cyclone Tracks 1851-2005, Geographic NAD83, NOAA (2006) [atlantic_hurricane_tracks_1851_2005_NOAA_2006

    Data.gov (United States)

    Louisiana Geographic Information Center — This Historical North Atlantic Tropical Cyclone Tracks file contains the 6-hourly (0000, 0600, 1200, 1800 UTC) center locations and intensities for all subtropical...

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

    Science.gov (United States)

    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.

  20. Tropical cyclone genesis in the Southern Hemisphere and its relationship with the ENSO

    Energy Technology Data Exchange (ETDEWEB)

    Kuleshov, Y.; Qi, L. [Australian Bureau of Meteorology, Melbourne, VIC (Australia). National Climate Centre; Chane Ming, F.; Chouaibou, I.; Hoareau, C. [UMR CNRS-Meteo-France-Univ. de la Reunion, La Reunion (France). Lab. de l' Atmosphere et des Cyclones; Roux, F. [Paul Sabatier Univ., CNRS, Toulouse (France). Lab. d' Aerologie

    2009-07-01

    Tropical cyclogenesis climatology over the South Indian and South Pacific Oceans has been developed using a new tropical cyclone (TC) archive for the Southern Hemisphere, and changes in geographical distribution of areas favourable for TC genesis related to changes in the El Nino-Southern Oscillation (ENSO) phases have been investigated. To explain these changes, large-scale environmental variables which influence TC genesis and development such as sea surface temperatures (SSTs), relative humidity in mid-troposphere, vertical wind shear and lower tropospheric vorticity have been examined. In the South Indian Ocean, reduction of TC genesis in the western part of the basin and its increase in the eastern part as well as displacement of the area favourable for TC genesis further away from the equator during La Nina events compared to El Nino events can be explained by changes in geographical distribution of relative humidity and vorticity across the basin as primary contributors; positive anomalies of SSTs observed during La Nina seasons in the eastern part of the basin additionally contribute to enhanced cyclogenesis near the Western Australia. In the South Pacific Ocean, changes in geographical distribution of relative humidity and vorticity appear to be the key large-scale environmental factors responsible for enhanced TC genesis in the eastern (western) part of the basin as well as for the northeast (southwest) shift of points of cyclogenesis during El Nino (La Nina) events, with vertical wind shear and SSTs as additional contributing large-scale environmental variables. (orig.)

  1. Modulation of western North Pacific tropical cyclone activity by the Atlantic Meridional Mode

    Science.gov (United States)

    Zhang, Wei; Vecchi, Gabriel A.; Villarini, Gabriele; Murakami, Hiroyuki; Rosati, Anthony; Yang, Xiaosong; Jia, Liwei; Zeng, Fanrong

    2017-01-01

    This study examines the year-to-year modulation of the western North Pacific (WNP) tropical cyclones (TC) activity by the Atlantic Meridional Mode (AMM) using both observations and the Geophysical Fluid Dynamics Laboratory Forecast-oriented Low Ocean Resolution Version of CM2.5 (FLOR) global coupled model. 1. The positive (negative) AMM phase suppresses (enhances) WNP TC activity in observations. The anomalous occurrence of WNP TCs results mainly from changes in TC genesis in the southeastern part of the WNP. 2. The observed responses of WNP TC activity to the AMM are connected to the anomalous zonal vertical wind shear (ZVWS) caused by AMM-induced changes to the Walker circulation. During the positive AMM phase, the warming in the North Atlantic induces strong descending flow in the tropical eastern and central Pacific, which intensifies the Walker cell in the WNP. The intensified Walker cell is responsible for the suppressed (enhanced) TC genesis in the eastern (western) part of the WNP by strengthening (weakening) ZVWS. 3. The observed WNPTC-AMM linkage is examined by the long-term control and idealized perturbations experiment with FLOR-FA. A suite of sensitivity experiments strongly corroborate the observed WNPTC-AMM linkage and underlying physical mechanisms.

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

    Science.gov (United States)

    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.

  3. Water budget and rapidly intensifying tropical cyclones over the western North Pacific

    Science.gov (United States)

    Gao, S.; Zhai, S.; Chen, B.; Li, T.

    2016-12-01

    Atmospheric Infrared Sounder (AIRS) relative humidity, Tropical Rainfall Measurement Mission (TRMM) 3B42 precipitation, Institut Français pour la Recherche et l'Exploitation de la Mer (IFREMER) evaporation, National Centers for Environmental Prediction (NCEP) FNL reanalysis and Joint Typhoon Warning Center (JTWC) tropical cyclone (TC) best track data are used to examine azimuthal mean and shear-relative water budget components associated with western North Pacific TCs of five intensity change categories: weakening, neutral, slowly intensifying, rapidly intensifying (initial) and rapid intensifying (continuing). The results show that: 1) In terms of azimuthal mean, evaporation plays an important role in both of the onset and continuation of storm rapid intensification (RI) and mid-level environmental relative humidity (ERH) within 600 km plays an important role in continuing RI. 2) Downshear left mid-level ERH and downshear right and upshear right evaporation are crucial for the onset of storm RI. 3) Upshear mid-level ERH, evaporation at all quadrants, upshear inner-core moisture flux convergence (MFC) and precipitation at all quadrants except for downshear left are important for continuing RI. 4) Storms undergoing continuing RI have more symmetric distributions of all the water budget components (i.e., ERH, precipitation, evaporation and MFC) than other storms. Our results suggest that different portions of water budget components play different roles in storm RI.

  4. Quantifying the Environmental Memory of Tropical Cyclones: Lingering Footprint or Climate Amnesia?

    Science.gov (United States)

    Schenkel, B. A.; Hart, R. E.

    2011-12-01

    One of the great remaining unanswered questions in tropical meteorology is why there are 90 tropical cyclones (TCs) globally, on average, per year as opposed to 10, 1000, or 10000 TCs. In contrast to extratropical cyclones whose annual frequency can be roughly calculated given the large scale characteristics of the mid-latitudes, there is no equivalent theory that even justifies the order of magnitude of TCs that occur globally each year. In spite of this, there appears to be a preferential spacing of approximately 1500-2000 km between TCs during multiple TC episodes in the Eastern North Pacific, North Atlantic, and Western North Pacific possibly suggesting that the number of storms in each basin is limited energetically by the environment. Reconciling these issues is fundamentally rooted in determining the role of TCs within the climate. Building upon previous research (e.g. Sobel and Camargo 2005, Hart et al. 2007), the following study seeks to take a preliminary step in addressing these questions by quantifying the spatiotemporal scales over which TCs and the large scale environment interact. Four-dimensional, storm-relative composites of raw variables, raw anomalies, and normalized anomalies for Western North Pacific TCs are utilized in the analysis presented here. Preliminary results show that the passage of a TC may be initially responsible for exciting a large scale cooling and drying of the atmospheric environment spanning the majority of the composite domain. Within two weeks, these anomalies are found to become localized over the region in which the TC directly passed through and most strongly manifest themselves as a drying of the lower and middle tropospheric environment. The spatial distribution of the moisture and temperature anomalies in the area immediately surrounding the TC track suggests that the suppression of convection potentially due to the underlying sea surface temperature cold wake induced by the TC is the predominant factor in anomaly

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

    Science.gov (United States)

    Brun, Julien

    Tropical Cyclones (TCs) intensity and frequency are expected to be impacted by climate change. Despite their destructive potential, these phenomena, which can produce heavy precipitation, are also an important source of freshwater. Therefore any change in frequency, seasonal timing and intensity of TCs is expected to strongly impact the regional water cycle and consequently the freshwater availability and distribution. This is critical, due to the fact that freshwater resources in the US are under stress due to the population growth and economic development that increasingly create more demands from agricultural, municipal and industrial uses, resulting in frequent over-allocation of water resources. In this study we concentrate on monitoring the impact of hurricanes and tropical storms on vegetation activity along their terrestrial tracks and investigate the underlying physical processes. To characterize and monitor the spatial organization and time of recovery of vegetation disturbance in the aftermath of major hurricanes over the entire southeastern US, a remote sensed framework based on MODIS enhanced vegetation index (EVI) was developed. At the SE scale, this framework was complemented by a water balance approach to estimate the variability in hurricane groundwater recharge capacity spatially and between events. Then we investigate the contribution of TCs (season totals and event by event) to the SE US annual precipitation totals from 2002 to 2011. A water budget approach applied at the drainage basins scale is used to investigate the partitioning of TCs' precipitation into surface runoff and groundwater system in the direct aftermath of major TCs. This framework allows exploring the contribution of TCs to annual precipitation totals and the consequent recharge of groundwater reservoirs across different physiographic regions (mountains, coastal and alluvial plains) versus the fraction that is quickly evacuated through the river network and surface runoff. Then

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

    Science.gov (United States)

    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

  7. Analyzing the impact of severe tropical cyclone Yasi on public health infrastructure and the management of noncommunicable diseases.

    Science.gov (United States)

    Ryan, Benjamin J; Franklin, Richard C; Burkle, Frederick M; Watt, Kerrianne; Aitken, Peter; Smith, Erin C; Leggat, Peter

    2015-02-01

    Traditionally, post disaster response activities have focused on immediate trauma and communicable diseases. In developed countries such as Australia, the post disaster risk for communicable disease is low. However, a "disease transition" is now recognized at the population level where noncommunicable diseases (NCDs) are increasingly documented as a post disaster issue. This potentially places an extra burden on health care resources and may have implications for disaster-management systems. With increasing likelihood of major disasters for all sectors of global society, there is a need to ensure that health systems, including public health infrastructure (PHI), can respond properly. Problem There is limited peer-reviewed literature on the impact of disasters on NCDs. Research is required to better determine both the impact of NCDs post disaster and their impact on PHI and disaster-management systems. A literature review was used to collect and analyze data on the impact of the index case event, Australia's Severe Tropical Cyclone Yasi (STC Yasi), on PHI and the management of NCDs. The findings were compared with data from other world cyclone events. The databases searched were MEDLINE, CINAHL, Google Scholar, and Google. The date range for the STC Yasi search was January 26, 2011 through May 2, 2013. No time limits were applied to the search from other cyclone events. The variables compared were tropical cyclones and their impacts on PHI and NCDs. The outcome of interest was to identify if there were trends across similar world events and to determine if this could be extrapolated for future crises. This research showed a tropical cyclone (including a hurricane and typhoon) can impact PHI, for instance, equipment (oxygen, syringes, and medications), services (treatment and care), and clean water availability/access that would impact both the treatment and management of NCDs. The comparison between STC Yasi and worldwide tropical cyclones found the challenges faced

  8. Prediction of tropical cyclone over North Indian Ocean using WRF model: sensitivity to scatterometer winds, ATOVS and ATMS radiances

    KAUST Repository

    Dodla, Venkata B.

    2016-05-03

    Tropical cyclone prediction, in terms of intensification and movement, is important for disaster management and mitigation. Hitherto, research studies were focused on this issue that lead to improvement in numerical models, initial data with data assimilation, physical parameterizations and application of ensemble prediction. Weather Research and Forecasting (WRF) model is the state-of-art model for cyclone prediction. In the present study, prediction of tropical cyclone (Phailin, 2013) that formed in the North Indian Ocean (NIO) with and without data assimilation using WRF model has been made to assess impacts of data assimilation. WRF model was designed to have nested two domains of 15 and 5 km resolutions. In the present study, numerical experiments are made without and with the assimilation of scatterometer winds, and radiances from ATOVS and ATMS. The model performance was assessed in respect to the movement and intensification of cyclone. ATOVS data assimilation experiment had produced the best prediction with least errors less than 100 km up to 60 hours and producing pre-deepening and deepening periods accurately. The Control and SCAT wind assimilation experiments have shown good track but the errors were 150-200 km and gradual deepening from the beginning itself instead of sudden deepening.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Ensemble tropical-extratropical cyclone coastal flood hazard assessment with climate change

    Science.gov (United States)

    Orton, P. M.; Lin, N.; Colle, B.

    2016-12-01

    A challenge with quantifying future changes in coastal flooding for the U.S. East Coast is that climate change has varying effects on different types of storms, in addition to raising mean sea levels. Moreover, future flood hazard uncertainties are large and come from many sources. Here, a new coastal flood hazard assessment approach is demonstrated that separately evaluates and then combines probabilities of storm tide generated from tropical cyclones (TCs) and extratropical cyclones (ETCs). The separation enables us to incorporate climate change impacts on both types of storms. The assessment accounts for epistemic storm tide uncertainty using an ensemble of different prior studies and methods of assessment, merged with uncertainty in climate change effects on storm tides and sea levels. The assessment is applied for New York Harbor, under the auspices of the New York City Panel on Climate Change (NPCC). In the New York Bight region and much of the U.S. East Coast, differing flood exceedance curve slopes for TCs and ETCs arise due to their differing physics. It is demonstrated how errors can arise for this region from mixing together storm types in an extreme value statistical analysis, a common practice when using observations. The effects of climate change on TC and ETC flooding have recently been assessed for this region, for TCs using a Global Climate Model (GCM) driven hurricane model with hydrodynamic modeling, and for ETCs using a GCM-driven multilinear regression-based storm surge model. The results of these prior studies are applied to our central estimates of the flood exceedance curve probabilities, transforming them for climate change effects. The results are useful for decision-makers because they highlight the large uncertainty in present-day and future flood risk, and also for scientists because they identify the areas where further research is most needed.

  11. Sensitivity of Tropical Cyclone Tracks and Intensity to Ocean Surface Temperature: Four Cases in Four Different Basins

    OpenAIRE

    Ren, Diandong; Lynch, Mervyn; Leslie, Lance M.; Lemarshall, John

    2014-01-01

    This study investigates the sensitivity of tropical cyclone (TC) motion and intensity to ocean surface fluxes that, in turn, are directly related to sea surface temperatures (SSTs). The Advanced Research version of the Weather Research and Forecast (WRF-ARW) model is used with an improved parameterisation of surface latent heat flux account for ocean salinity. The WRF-ARW simulations compare satisfactorily with the NCEP/NCAR reanalysis for atmospheric fields and remotely sensed precipitation ...

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

    Science.gov (United States)

    Emanuel, Kerry; Sobel, Adam

    2013-06-01

    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. Response to local forcing is estimated using the weak temperature gradient (WTG) approximation. The surface temperature is calculated using a thin slab ocean so as to maintain surface energy balance. Forcing is varied by changing the solar constant, atmospheric CO2 concentration, surface wind speed, and the convergence of upper ocean heat flux. These experiments show that precipitation and variables related to TC activity are not unique functions of SST on time scales long enough for surface energy balance to be maintained. Precipitation varies inversely with SST in experiments in which the surface wind speed is varied. At low wind speed, the WTG experiments reveal a regime of high relative SST and low precipitation, which is maintained by increased transmission of longwave radiation from the surface directly to space through a dry troposphere. In general, TC potential intensity and genesis potential vary much more rapidly with SST in response to varying surface wind speed than in response to other forcings. Local changes in TC potential intensity are highly correlated with local changes in SST, showing that relative SST is a good proxy for potential intensity when forcing is strictly local, but it cannot capture potentially important changes in potential intensity that arise from global-scale changes in forcing.

  13. Remote effects of tropical storm Cristobal upon a cut-off cyclone over Europe in August 2002

    Science.gov (United States)

    Enomoto, T.; Ohfuchi, W.; Nakamura, H.; Shapiro, M. A.

    2007-04-01

    In August 2002, many parts of central Europe were affected by heavy precipitation and flooding caused by a cut-off cyclone. This study shows that this cyclone developed as a result of the propagation of a Rossby wave packet. The wave-packet propagation along the relatively weak subtropical jet was accompanied by wave-breaking and re-emission in the subtropics. In particular, there was an interaction between the Rossby wave packet and a precipitation band along the east coast of North America associated with tropical storm Cristobal. This interaction had a significant influence upon the formation of the European cut-off low. Results from numerical simulations from two different initial conditions are investigated to study this interaction. Downstream influences from tropical storm Cristobal upon the development of this cyclone and associated flooding precipitation are confirmed by sensitivity analysis using ensemble forecasts. It is concluded from analysis and simulations that poor forecast skills of tropical storm Cristobal affected the predictability of the European cut-off low.

  14. Operation of lightning detection network and micro-satellites for nowcast of thunderstorm and tropical cyclone activities

    Science.gov (United States)

    Sato, Mitsuteru; Takahashi, Yukihiro; Kubota, Hisayuki; Momota, Eriko; Marciano, Joel

    2017-04-01

    Lightning activity represents the thunderstorm activity, namely, the intensity and area of precipitation and/or updraft. Thunderstorm is also important as a proxy of the energy input from ocean to atmosphere inside tropical cyclone, meaning that if we could monitor the thunderstorm with lightning we could predict the maximum wind velocity or minimum pressure near the center of the tropical cyclone by one or two days before. Constructing ELF observation sites, international/nation-wide VLF observation networks and a regional dense network of slow antennas installed at about 50 automated weather stations in Metro Manila, we plan to establish the monitoring system for thunderstorm development in western pacific warm pool (WPWP) where typhoon is formed and in detail in Metro Manila. Making use of the lightning activity data measured by the ground-based networks, we could operate micro-satellites, such as DIWATA-1 developed by Philippines, to make stereo imaging for estimation of 3-D structure and the speed of development of thunderstorm. We would establish a new methodology to obtain very detail semi-real time information that cannot be achieved only with existing observation facilities, such as meteorological radar or large meteorological satellite. Using this new system we try to issue nowcast for the local thunderstorm and for tropical cyclones. The 5-year project in Philippines will start in coming April.

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

    Directory of Open Access Journals (Sweden)

    M. Yamamoto

    2014-07-01

    Full Text Available 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.

  16. Modulating Effects of Mesoscale Oceanic Eddies on Sea Surface Temperature Response to Tropical Cyclones Over the Western North Pacific

    Science.gov (United States)

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

    2018-01-01

    The impact of mesoscale oceanic eddies on the temporal and spatial characteristics of sea surface temperature (SST) response to tropical cyclones is investigated in this study based on composite analysis of cyclone-eddy interactions over the western North Pacific. The occurrence times of maximum cooling, recovery time, and spatial patterns of SST response are specially evaluated. The influence of cold-core eddies (CCEs) renders the mean occurrence time of maximum SST cooling to become about half a day longer than that in eddy-free condition, while warm-core eddies (WCEs) have little effect on this facet. The recovery time of SST cooling also takes longer in presence of CCEs, being overall more pronounced for stronger or slower tropical cyclones. The effect of WCEs on the recovery time is again not significant. The modulation of maximum SST decrease by WCEs for category 2-5 storms is found to be remarkable in the subtropical region but not evident in the tropical region, while the role of CCEs is remarkable in both regions. The CCEs are observed to change the spatial characteristics of SST response, with enhanced SST decrease initially at the right side of storm track. During the recovery period the strengthened SST cooling by CCEs propagates leftward gradually, with a feature similar as both the westward-propagating eddies and the recovery of cold wake. These results underscore the importance of resolving mesoscale oceanic eddies in coupled numerical models to improve the prediction of storm-induced SST response.

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

    Science.gov (United States)

    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 shallow (D26) and varies seasonally. These regions where used to compare variability with respect to SST recovery time and the SST maximum change (ΔSSTmax) 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 (5days). Difference between both regions can be described with respect to the

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

    Science.gov (United States)

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

    2014-12-01

    The JPL Tropical Cyclone Information System (TCIS) brings together satellite, aircraft, and model forecast data from several NASA, NOAA, and other data centers to assist researchers in comparing and analyzing data related to tropical cyclones. The TCIS has been supporting specific science field campaigns, such as the Genesis and Rapid Intensification Processes (GRIP) campaign and the Hurricane and Severe Storm Sentinel (HS3) campaign, by creating near real-time (NRT) data visualization portals. These portals are intended to assist in mission planning, enhance the understanding of current physical processes, and improve model data by comparing it to satellite and aircraft observations. The TCIS NRT portals allow the user to view plots on a Google Earth interface. To compliment these visualizations, the team has been working on developing data analysis tools to let the user actively interrogate areas of Level 2 swath and two-dimensional plots they see on their screen. As expected, these observation and model data are quite voluminous and bottlenecks in the system architecture can occur when the databases try to run geospatial searches for data files that need to be read by the tools. To improve the responsiveness of the data analysis tools, the TCIS team has been conducting studies on how to best store Level 2 swath footprints and run sub-second geospatial searches to discover data. The first objective was to improve the sampling accuracy of the footprints being stored in the TCIS database by comparing the Java-based NASA PO.DAAC Level 2 Swath Generator with a TCIS Python swath generator. The second objective was to compare the performance of four database implementations - MySQL, MySQL+Solr, MongoDB, and PostgreSQL - to see which database management system would yield the best geospatial query and storage performance. The final objective was to integrate our chosen technologies with our Joint Probability Density Function (Joint PDF), Wave Number Analysis, and

  19. Understanding and simulating the link between African easterly waves and Atlantic tropical cyclones using a regional climate model: the role of domain size and lateral boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Caron, Louis-Philippe [MISU, Stockholm University, Stockholm (Sweden); Universite du Quebec a Montreal, CRCMD Network, Montreal, QC (Canada); Jones, Colin G. [Swedish Meterological and Hydrological Institute, Rossby Center, Norrkoeping (Sweden)

    2012-07-15

    Using a suite of lateral boundary conditions, we investigate the impact of domain size and boundary conditions on the Atlantic tropical cyclone and african easterly Wave activity simulated by a regional climate model. Irrespective of boundary conditions, simulations closest to observed climatology are obtained using a domain covering both the entire tropical Atlantic and northern African region. There is a clear degradation when the high-resolution model domain is diminished to cover only part of the African continent or only the tropical Atlantic. This is found to be the result of biases in the boundary data, which for the smaller domains, have a large impact on TC activity. In this series of simulations, the large-scale Atlantic atmospheric environment appears to be the primary control on simulated TC activity. Weaker wave activity is usually accompanied by a shift in cyclogenesis location, from the MDR to the subtropics. All ERA40-driven integrations manage to capture the observed interannual variability and to reproduce most of the upward trend in tropical cyclone activity observed during that period. When driven by low-resolution global climate model (GCM) integrations, the regional climate model captures interannual variability (albeit with lower correlation coefficients) only if tropical cyclones form in sufficient numbers in the main development region. However, all GCM-driven integrations fail to capture the upward trend in Atlantic tropical cyclone activity. In most integrations, variations in Atlantic tropical cyclone activity appear uncorrelated with variations in African easterly wave activity. (orig.)

  20. Remote Sensing Assessment of Forest Disturbance across Complex Mountainous Terrain: The Pattern and Severity of Impacts of Tropical Cyclone Yasi on Australian Rainforests

    Directory of Open Access Journals (Sweden)

    Robinson I. Negrón-Juárez

    2014-06-01

    Full Text Available Topography affects the patterns of forest disturbance produced by tropical cyclones. It determines the degree of exposure of a surface and can alter wind characteristics. Whether multispectral remote sensing data can sense the effect of topography on disturbance is a question that deserves attention given the multi-scale spatial coverage of these data and the projected increase in intensity of the strongest cyclones. Here, multispectral satellite data, topographic maps and cyclone surface wind data were used to study the patterns of disturbance in an Australian rainforest with complex mountainous terrain produced by tropical cyclone Yasi (2011. The cyclone surface wind data (H*wind was produced by the Hurricane Research Division of the National Oceanic and Atmospheric Administration (HRD/NOAA, and this was the first time that this data was produced for a cyclone outside of United States territory. A disturbance map was obtained by applying spectral mixture analyses on satellite data and presented a significant correlation with field-measured tree mortality. Our results showed that, consistent with cyclones in the southern hemisphere, multispectral data revealed that forest disturbance was higher on the left side of the cyclone track. The highest level of forest disturbance occurred in forests along the path of the cyclone track (±30°. Levels of forest disturbance decreased with decreasing slope and with an aspect facing off the track of the cyclone or away from the dominant surface winds. An increase in disturbance with surface elevation was also observed. However, areas affected by the same wind intensity presented increased levels of disturbance with increasing elevation suggesting that complex terrain interactions act to speed up wind at higher elevations. Yasi produced an important offset to Australia’s forest carbon sink in 2010. We concluded that multispectral data was sensitive to the main effects of complex topography on disturbance

  1. Reconstruction of the North Atlantic tropical cyclones in Azores for the last 800 years.

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2013-04-01

    The Australian Bureau of Meteorology (BoM) issues predictions of tropical cyclone (TC) activity in the Australian and South Pacific regions in the October before the TC season (November to April). Currently, these predictions utilise a statistical model based on the historical relationship between tropical cyclone activity and (i) sea surface temperature anomalies in the Equatorial Pacific (NINO3.4 region) and (ii) the Southern Oscillation Index over the past few decades. Variations in the El Niño-Southern Oscillation (ENSO)-TC relationship that are not contained within the historical record can lead to deficiencies in future predictions. The use of dynamical (physics-based) climate models (GCMs) offers an alternative to statistical TC prediction schemes. Any changes to the environment (whatever their character or cause) are incorporated in the analyses used to initialise a dynamical model. As part of the Pacific-Australia Climate Change Science and Adaptation Planning (PACCSAP) Program, BoM is developing dynamically-based seasonal TC predictions for the Australian, South Pacific and North-West Pacific regions. The seasonal TC predictions from two fully-coupled GCMs are evaluated and compared. These models are BoM's Predictive Ocean-Atmosphere Model for Australia (POAMA) and the Japan Meteorological Agency/Meteorological Research Institute Coupled GCM (JMA/MRI-CGCM). The resolution of POAMA's atmospheric component is T42 (~2.5° x 2.5°), while JMA/MRI-CGCM is T95 (~1.8° x 1.8°). Two TC tracking methods are employed and applied to both models to evaluate the influence of model composition and tracking technique on seasonal TC predictions. In the more traditional TC detection scheme TCs are identified where 850-hPa relative vorticity is a maximum (minimum in the Southern Hemisphere) and exceeds a certain threshold. Additionally, the 500-200-hPa thickness and the difference in maximum winds at 850 and 200 hPa are used to differentiate tropical from extratropical

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.; hide

    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.

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

    Science.gov (United States)

    Hashimoto, A.

    2014-12-01

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

  7. Tropical cyclone genesis in the Southern Hemisphere and its relationship with the ENSO

    Directory of Open Access Journals (Sweden)

    Y. Kuleshov

    2009-06-01

    Full Text Available Tropical cyclogenesis climatology over the South Indian and South Pacific Oceans has been developed using a new tropical cyclone (TC archive for the Southern Hemisphere, and changes in geographical distribution of areas favourable for TC genesis related to changes in the El Niño-Southern Oscillation (ENSO phases have been investigated. To explain these changes, large-scale environmental variables which influence TC genesis and development such as sea surface temperatures (SSTs, relative humidity in mid-troposphere, vertical wind shear and lower tropospheric vorticity have been examined. In the South Indian Ocean, reduction of TC genesis in the western part of the basin and its increase in the eastern part as well as displacement of the area favourable for TC genesis further away from the equator during La Niña events compared to El Niño events can be explained by changes in geographical distribution of relative humidity and vorticity across the basin as primary contributors; positive anomalies of SSTs observed during La Niña seasons in the eastern part of the basin additionally contribute to enhanced cyclogenesis near the Western Australia. In the South Pacific Ocean, changes in geographical distribution of relative humidity and vorticity appear to be the key large-scale environmental factors responsible for enhanced TC genesis in the eastern (western part of the basin as well as for the northeast (southwest shift of points of cyclogenesis during El Niño (La Niña events, with vertical wind shear and SSTs as additional contributing large-scale environmental variables.

  8. Characterizing the Variations of the motion of the North Atlantic tropical cyclones

    Science.gov (United States)

    Laurencin, Chelsey Nakita; Misra, Vasubandhu

    2017-11-01

    In this study, we examine the seasonal and interannual variability of the North Atlantic (NATL) tropical cyclone (TC) motion from the historical Hurricane Database (HURDAT2) over the period 1988-2014. We characterize these motions based on their position, lifecycle, and seasonal cycle. The main findings of this study include: (1) of the 11,469 NATL TC fixes examined between 1988 and 2014, 81% of them had a translation speed of 40 mph) are exclusively found north of 30 N, the slow-moving TCs have a wide range of latitude. This is largely a consequence of the background steering flow being weaker (stronger) in the tropical (higher) latitudes with a minimum around the subtropical latitudes of NATL; (3) there is an overall decrease in the frequency of all categories of translation speed of TCs in warm relative to cold El Niño Southern Oscillation (ENSO) years. However, in terms of the percentage change, TCs with a translation speed in the range of 10-20 mph display the most change (42%) in warm relative to cold ENSO years; and (4) there is an overall decrease in frequency across all categories of TC translation speed in small relative to large Atlantic Warm Pool years, but in terms of percentage change in the frequency of TCs, there is a significant and comparable change in the frequency over a wider range of translation speeds than the ENSO composites. This last finding suggests that Atlantic Warm Pool variations have a more profound impact on the translation speed of Atlantic TCs than ENSO.

  9. Perturbations to the lower ionosphere by tropical cyclone Evan in the South Pacific Region

    Science.gov (United States)

    Kumar, Sushil; NaitAmor, Samir; Chanrion, Olivier; Neubert, Torsten

    2017-08-01

    Very low frequency (VLF) electromagnetic signals from navigational transmitters propagate worldwide in the Earth-ionosphere waveguide formed by the Earth and the electrically conducting lower ionosphere. Changes in the signal properties are signatures of variations in the conductivity of the reflecting boundary of the lower ionosphere which is located in the mesosphere and lower thermosphere, and their analysis is, therefore, a way to study processes in these remote regions. Here we present a study on amplitude perturbations of local origin on the VLF transmitter signals (NPM, NLK, NAA, and JJI) observed during tropical cyclone (TC) Evan, 9-16 December 2012 when TC was in the proximity of the transmitter-receiver links. We observed a maximum amplitude perturbation of 5.7 dB on JJI transmitter during 16 December event. From Long Wave Propagation Capability model applied to three selected events we estimate a maximum decrease in the nighttime D region reference height (H') by 5.2 km (13 December, NPM) and maximum increase in the daytime D region H' by 6.1 km and 7.5 km (14 and 16 December, JJI). The results suggest that the TC caused the neutral densities of the mesosphere and lower thermosphere to lift and sink (bringing the lower ionosphere with it), an effect that may be mediated by gravity waves generated by the TC. The perturbations were observed before the storm was classified as a TC, at a time when it was a tropical depression, suggesting the broader conclusion that severe convective storms, in general, perturb the mesosphere and the stratosphere through which the perturbations propagate.

  10. A mechanism for long-term changes of Atlantic tropical cyclone intensity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Liguang; Tao, Li [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing, Jiangsu (China)

    2011-05-15

    Although previous studies reported upward trends in the basin-wide average lifetime, annual frequency, proportion of intense hurricanes and annual accumulated power dissipation index of Atlantic tropical cyclones (TCs) over the past 30 years, the basin-wide intensity did not increase significantly with the rising sea surface temperature (SST). Observational analysis and numerical simulation conducted in this study suggest that Sahel rainfall is the key to understanding of the long-term change of Atlantic TC intensity. The long-term changes of the basin-wide TC intensity are generally associated with variations in Sahara air layer (SAL) activity and vertical wind shear in the main development region (MDR), both of which are highly correlated with Sahel rainfall. The drying Sahel corresponds to an equatorward shift in the African easterly jet and African easterly wave activity, introducing the SAL to lower latitudes and increasing the MDR vertical wind shear. As a result, Atlantic TCs are more vulnerable to the suppressing effects of the SAL and vertical wind shear. Since the SST warming, especially in the tropical Indian Ocean, is a dominant factor for the Sahel drying that occurred over the past 30 years, it is suggested that the remote effect of SST warming is important for the long-term change of Atlantic TC intensity. Although influence of the AMO warm phase that started in the early 1990s alone can provide a favorable condition for TC intensification, its influence may have been offset by the influence of the ongoing SST warming, particularly in the Indian Ocean. As a result, there was no significant trend observed in the basin-wide average and peak intensity of Atlantic TCs. (orig.)

  11. Factors affecting the simulated trajectory and intensification of Tropical Cyclone Yasi (2011)

    Science.gov (United States)

    Parker, Chelsea L.; Lynch, Amanda H.; Mooney, Priscilla A.

    2017-09-01

    This study investigates the sensitivity of the simulated trajectory, intensification, and forward speed of Tropical Cyclone Yasi to initial conditions, physical parameterizations, and sea surface temperatures. Yasi was a category 5 storm that made landfall in Queensland, Australia in February 2011. A series of simulations were performed using WRF-ARW v3.4.1 driven by ERA-Interim data at the lateral boundaries. To assess these simulations, a new simple skill score is devised to summarize the deviation from observed conditions at landfall. The results demonstrate the sensitivity to initial condition resolution and the need for a new initialization dataset. Ensemble testing of physics parameterizations revealed strong sensitivity to cumulus schemes, with a trade-off between trajectory and intensity accuracy. The Tiedtke scheme produces an accurate trajectory evolution and landfall location. The Kain Fritch scheme is associated with larger errors in trajectory due to a less active shallow convection over the ocean, leading to warmer temperatures at the 700 mb level and a stronger, more poleward steering flow. However, the Kain Fritsch scheme produces more accurate intensities and translation speeds. Tiedtke-derived intensities were weaker due to suppression of deep convection by active shallow convection. Accurate representation of the sea surface temperature through correcting a newly discovered SST lag in reanalysis data or increasing resolution of SST data can improve the simulation. Higher resolution increases relative vorticity and intensity. However, the sea surface boundary had a more pronounced effect on the simulation with the Tiedtke scheme due to its moisture convergence trigger and active shallow convection over the tropical ocean.

  12. An analysis of observed large air-sea temperature differences in tropical cyclones

    Energy Technology Data Exchange (ETDEWEB)

    Kepert, J.D. [Bureau of Meteorology Research Centre, Melbourne (Australia)

    1994-12-31

    At high wind speeds over the sea, the lower part of the atmospheric boundary layer becomes filled with spray. In recent years, much attention has been devoted to the question of whether the evaporation from these droplets contributes significantly to the total sea-air evaporative flux under such conditions. Direct observations of turbulent fluxes of heat, moisture and momentum over the sea at moderately high wind speeds were taken during HEXOS Main Experiment (HEXMAX). (HEXOS is the Humidity Exchange Over the Sea program.) An analysis of these results shows that the neutral transfer coefficient is nearly constant with wind speed, up to about 18 m/s, albeit with considerable scatter about the mean. Here the author describes a preliminary investigation of the possible effects evaporation of sea spray could have on the vertical structure of the atmospheric boundary layer at high wind speeds. The remainder of the paper consists of a brief discussion of a radiosonde ascent launched from a ship during a tropical cyclone, a description of the turbulent closure model used to investigate the role of the various physical processes, followed by a discussion of the model results and their relationship to the observation.

  13. Latitudinal Change of Tropical Cyclone Maximum Intensity in the Western North Pacific

    Directory of Open Access Journals (Sweden)

    Jae-Won Choi

    2016-01-01

    Full Text Available This study obtained the latitude where tropical cyclones (TCs show maximum intensity and applied statistical change-point analysis on the time series data of the average annual values. The analysis results found that the latitude of the TC maximum intensity increased from 1999. To investigate the reason behind this phenomenon, the difference of the average latitude between 1999 and 2013 and the average between 1977 and 1998 was analyzed. In a difference of 500 hPa streamline between the two periods, anomalous anticyclonic circulations were strong in 30°–50°N, while anomalous monsoon trough was located in the north of South China Sea. This anomalous monsoon trough was extended eastward to 145°E. Middle-latitude region in East Asia is affected by the anomalous southeasterlies due to these anomalous anticyclonic circulations and anomalous monsoon trough. These anomalous southeasterlies play a role of anomalous steering flows that make the TCs heading toward region in East Asia middle latitude. As a result, TCs during 1999–2013 had higher latitude of the maximum intensity compared to the TCs during 1977–1998.

  14. Insurance mechanisms for tropical cyclones and droughts in Pacific Small Island Developing States

    Directory of Open Access Journals (Sweden)

    Florent Baarsch

    2016-03-01

    Full Text Available One group of locations significantly affected by climate-related losses and damage is the Small Island Developing States (SIDS. One mechanism aiming to reduce such adverse impacts is insurance, with a wide variety of products and models available. Insurance for climate-related hazards affecting Pacific SIDS has not been investigated in detail. This article contributes to filling this gap by exploring how insurance mechanisms might be implemented in the Pacific SIDS for tropical cyclones and droughts. The study examines opportunities and constraints or limitations of some existing insurance mechanisms and programmes as applied to the Pacific SIDS. Eight insurance mechanisms are compared and discussed regarding the premium cost compared to the gross domestic product per capita, the amount of payout compared to the damage cost, the reserve and reinsurance, and the disaster risk reduction incentives. As such, this article offers a decision-making tool on insurance development for the Pacific SIDS. Ultimately, implementing disaster insurance for the Pacific SIDS depends on political will and external technical and financial assistance.

  15. Decreasing trend of tropical cyclone frequency in 228-year high-resolution AGCM simulations

    Science.gov (United States)

    Sugi, Masato; Yoshimura, Jun

    2012-10-01

    We conducted 228-year long, three-member ensemble simulations using a high resolution (60 km grid size) global atmosphere model, MRI-AGCM3.2, with prescribed sea surface temperature and greenhouse gases and aerosols from 1872 to 2099. We found a clear decreasing trend of global tropical cyclone (TC) frequency throughout the 228 years of the simulation. We also found a significant multidecadal variation (MDV) in the long term variation of Northern Hemisphere and Southern Hemisphere TC count in addition to the decreasing trend. The decreasing trend and MDV in the long term variation of TC count correspond well to a similar decreasing trend and MDV of upward mass flux averaged over the TC genesis region and active TC season. It has been shown that the upward mass flux decreases primarily because the rate of increase of dry static stability, which is close to that of surface specific humidity, is much larger than the rate of increase of precipitation, which is nearly the same as that of atmospheric radiative cooling. Thus, it is suggested that the decreasing trend of TC count is mainly caused by the decreasing trend of upward mass flux associated with the increasing dry static stability.

  16. A Study on the Effects of the Ice Microphysics on Tropical Cyclones

    Directory of Open Access Journals (Sweden)

    Masanori Yamasaki

    2013-01-01

    Full Text Available The effects of the ice microphysical processes on the development of weak vortices and tropical cyclones (TCs are examined by numerical experiments with a nonhydrostatic model. Since it has been understood that the ice phase generally enhances the eyewall circulation in strong TCs because of additional heat release and insignificant effect of rainwater evaporation, this study focuses on the development of relatively weak vortices and TCs. Some past studies showed that the development is slower by the effects of the ice phase through cooling due to the melting of snow and graupel, whereas this study indicates that cooling due to evaporation of rainwater in the subcloud layer plays a much more important role in the slower development, and much more solid substances in the mid-troposphere, which are produced through the ice phase processes, contribute to more rainwater evaporation in the subcloud layer. The relative importance of many processes of the ice microphysics is also examined as a basis for future improvements of parameterization of the microphysical processes.

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

    Science.gov (United States)

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

    2015-04-01

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

  18. Simulated sensitivity of tropical cyclone track to the moisture in an idealized monsoon gyre

    Science.gov (United States)

    Yan, Ziyu; Ge, Xuyang; Guo, Bingyao

    2017-12-01

    In this study, the sensitivity of tropical cyclone (TC) track to the moisture condition in a nearby monsoon gyre (MG) is investigated. Numerical simulations reveal that TC track is highly sensitive to the spatial distribution of relative humidity (RH). In an experiment conducted with higher (lower) RH in the eastern (western) semicircle of an MG, the TC experiences a sharp northward turning. In contrast, when the RH pattern is reversed, the simulated TC does not show a sharp northward turning. The RH distribution modulates the intensity and structure of both the TC and MG, so that when the TC is initially embedded in a moister environment, convection is enhanced in the outer core, which favors an expansion of the outer core size. A TC with a larger outer size has greater beta-effect propagation, favoring a faster westward translational speed. Meanwhile, higher RH enhances the vorticity gradient within the MG and promotes a quicker attraction between the TC and MG centers through vorticity segregation process. These cumulative effects cause the TC to collocate with the MG center. Once the coalescence process takes place, the energy dispersion associated with the TC and MG is enhanced, which rapidly strengthens southwesterly flows on the eastern flanks. The resulting steering flow leads the TC to take a sharp northward track.

  19. Decadal change of Tropical Cyclone Activity over western North Pacific around late-1990s

    Science.gov (United States)

    He, H.; Yang, J.; Mao, R.; Wang, Y.; Gong, D.

    2014-12-01

    A pronounced decadal change of tropical cyclone (TC) activity was identified over western North Pacific (WNP) around late-1990s. After late-1990s, the WNP total TC genesis number exhibited an evident decrease, particularly over southern WNP region (S-WNP: 5oN-20oN), which was mainly caused by reduced vorticity and descending anomalies. We also detected a significant northward migration of TC genesis from 17.2°N to 18.7°N. The above TC genesis change is attributed to the weakening of monsoon trough and local Hadley cell that is associated with sea surface temperature climate shift around the late-1990s. In terms of three prevailing TC tracks changes, the northwestward-moving track (II) became the most dominant prevailing track mode while the westward-moving track (I) became weaker, and the northeastward-recurving track (III) had a westward shift. The track shifts primarily resulted from the large-scale steering flows change, which also had played a vital role in the modulation of TC regional duration. Thus, the subtropical East Asia tended to have a higher risk of encountering TC while the Southern China had a lower risk. Additionally, a visual reduction was seen in both number and proportion of typhoons reaching categories 1 and 2, and a remarkable poleward migration was also recognized in the average latitudes where TCs have achieved their lifetime-maximum intensity.

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

    Science.gov (United States)

    Wang, Xidong; Liu, Hailong

    2016-01-01

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

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

    Science.gov (United States)

    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.

  2. Development of a diagnosis index of tropical cyclones affecting the Korean Peninsula

    Science.gov (United States)

    Choi, Jae-Won; Cha, Yumi

    2016-06-01

    This study has developed the index for diagnosis on possibility that tropical cyclones (TCs) affect Korean Peninsula. This index is closely related to the strength of the western North Pacific subtropical high (WNPSH), which is calculated as a difference in meridional wind between at the highest correlation area (around Korean Peninsula) and at the lowest correlation area (sea southeast of Japan) through a correlation analysis between TC frequency that affects Korean Peninsula and 500 hPa meridional wind. In low frequency years that selected from Korea affecting TC index, anomalous northeasterly is strengthened from Korea to the South China Sea because the center of anomalous anticyclonic circulation is located to northwest of Korean Peninsula. Thus, TCs tend to move westward from the sea east of the Philippines to the mainland China. On the other hand, in high frequency years, anomalous southwesterly serves as steering flow that more TCs move toward Korean Peninsula because the center of anomalous anticyclonic circulation is located to sea east of Japan. Consequently, this study suggests that if this index is calculated using real time 500 hPa meridional winds that forecasted by dynamic models during the movement of TCs, the possibility that TCs approach Korean Peninsula can be diagnosed in real time.

  3. Shipwreck rates reveal Caribbean tropical cyclone response to past radiative forcing.

    Science.gov (United States)

    Trouet, Valerie; Harley, Grant L; Domínguez-Delmás, Marta

    2016-03-22

    Assessing the impact of future climate change on North Atlantic tropical cyclone (TC) activity is of crucial societal importance, but the limited quantity and quality of observational records interferes with the skill of future TC projections. In particular, North Atlantic TC response to radiative forcing is poorly understood and creates the dominant source of uncertainty for twenty-first-century projections. Here, we study TC variability in the Caribbean during the Maunder Minimum (MM; 1645-1715 CE), a period defined by the most severe reduction in solar irradiance in documented history (1610-present). For this purpose, we combine a documentary time series of Spanish shipwrecks in the Caribbean (1495-1825 CE) with a tree-growth suppression chronology from the Florida Keys (1707-2009 CE). We find a 75% reduction in decadal-scale Caribbean TC activity during the MM, which suggests modulation of the influence of reduced solar irradiance by the cumulative effect of cool North Atlantic sea surface temperatures, El Niño-like conditions, and a negative phase of the North Atlantic Oscillation. Our results emphasize the need to enhance our understanding of the response of these oceanic and atmospheric circulation patterns to radiative forcing and climate change to improve the skill of future TC projections.

  4. Shipwreck rates reveal Caribbean tropical cyclone response to past radiative forcing

    Science.gov (United States)

    Trouet, Valerie; Harley, Grant L.; Domínguez-Delmás, Marta

    2016-03-01

    Assessing the impact of future climate change on North Atlantic tropical cyclone (TC) activity is of crucial societal importance, but the limited quantity and quality of observational records interferes with the skill of future TC projections. In particular, North Atlantic TC response to radiative forcing is poorly understood and creates the dominant source of uncertainty for twenty-first-century projections. Here, we study TC variability in the Caribbean during the Maunder Minimum (MM; 1645-1715 CE), a period defined by the most severe reduction in solar irradiance in documented history (1610-present). For this purpose, we combine a documentary time series of Spanish shipwrecks in the Caribbean (1495-1825 CE) with a tree-growth suppression chronology from the Florida Keys (1707-2009 CE). We find a 75% reduction in decadal-scale Caribbean TC activity during the MM, which suggests modulation of the influence of reduced solar irradiance by the cumulative effect of cool North Atlantic sea surface temperatures, El Niño-like conditions, and a negative phase of the North Atlantic Oscillation. Our results emphasize the need to enhance our understanding of the response of these oceanic and atmospheric circulation patterns to radiative forcing and climate change to improve the skill of future TC projections.

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

    Directory of Open Access Journals (Sweden)

    Andrew W Tweel

    Full Text Available 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.

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

    Science.gov (United States)

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

    Science.gov (United States)

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

    2014-12-04

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. The response of the Ocean Surface Boundary Layer and Langmuir turbulence to tropical cyclones

    Science.gov (United States)

    Wang, Dong; Kukulka, Tobias; Reichl, Brandon; Hara, Tetsu; Ginis, Isaac

    2016-11-01

    The interaction of turbulent ocean surface boundary layer (OSBL) currents and the surface waves' Stokes drift generates Langmuir turbulence (LT), which enhances OSBL mixing. This study investigates the response of LT to extreme wind and complex wave forcing under tropical cyclones (TCs), using a large eddy simulation (LES) approach based on the wave-averaged Navier-Stokes equations. We simulate the OSBL response to TC systems by imposing the wind forcing of an idealized TC storm model, covering the entire horizontal extent of the storm systems. The Stokes drift vector that drives the wave forcing in the LES is determined from realistic spectral wave simulations forced by the same wind fields. We find that the orientations of Langmuir cells are vertically uniform and aligned with the wind in most regions despite substantial wind-wave misalignment in TC conditions. LT's penetration depth is related to Stokes drift depth and limited by OSBL depth. A wind-projected surface layer Langmuir number is proposed and successfully applied to scale turbulent vertical velocity variance in extreme TC conditions. Current affiliation: Princeton University/NOAA GFDL.

  11. Ensemble Kalman Filter data assimilation and storm surge experiments of tropical cyclone Nargis

    Directory of Open Access Journals (Sweden)

    Le Duc

    2015-07-01

    Full Text Available Data assimilation experiments on Myanmar tropical cyclone (TC, Nargis, using the Local Ensemble Transform Kalman Filter (LETKF method and the Japan Meteorological Agency (JMA non-hydrostatic model (NHM were performed to examine the impact of LETKF on analysis performance in real cases. Although the LETKF control experiment using NHM as its driving model (NHM–LETKF produced a weak vortex, the subsequent 3-day forecast predicted Nargis’ track and intensity better than downscaling from JMA's global analysis. Some strategies to further improve the final analysis were considered. They were sea surface temperature (SST perturbations and assimilation of TC advisories. To address SST uncertainty, SST analyses issued by operational forecast centres were used in the assimilation window. The use of a fixed source of SST analysis for each ensemble member was more effective in practice. SST perturbations were found to have slightly positive impact on the track forecasts. Assimilation of TC advisories could have a positive impact with a reasonable choice of its free parameters. However, the TC track forecasts exhibited northward displacements, when the observation error of intensities was underestimated in assimilation of TC advisories. The use of assimilation of TC advisories was considered in the final NHM–LETKF by choosing an appropriate set of free parameters. The extended forecast based on the final analysis provided meteorological forcings for a storm surge simulation using the Princeton Ocean Model. Probabilistic forecasts of the water levels at Irrawaddy and Yangon significantly improved the results in the previous studies.

  12. Objective determination of the extratropical transition of tropical cyclones in the Northern Hemisphere

    Directory of Open Access Journals (Sweden)

    Joshua Studholme

    2015-05-01

    Full Text Available Extratropical transition (ET has eluded objective identification since the realisation of its existence in the 1970s. Recent advances in numerical, computational models have provided data of higher resolution than previously available. In conjunction with this, an objective characterisation of the structure of a storm has now become widely accepted in the literature. Here we present a method of combining these two advances to provide an objective method for defining ET. The approach involves applying K-means clustering to isolate different life-cycle stages of cyclones and then analysing the progression through these stages. This methodology is then tested by applying it to five recent years from the European Centre of Medium-Range Weather Forecasting operational analyses. It is found that this method is able to determine the general characteristics for ET in the Northern Hemisphere. Between 2008 and 2012, 54% (±7, 32 of 59 of Northern Hemisphere tropical storms are estimated to undergo ET. There is great variability across basins and time of year. To fully capture all the instances of ET is necessary to introduce and characterise multiple pathways through transition. Only one of the three transition types needed has been previously well-studied. A brief description of the alternate types of transitions is given, along with illustrative storms, to assist with further study.

  13. Pacific island tropical cyclones are more frequent and globally relevant, yet less studied

    Directory of Open Access Journals (Sweden)

    Thomas Edward Marler

    2014-10-01

    Full Text Available Typhoon Haiyan devastated the Philippines in 2013 and illuminates the fact that the majority of tropical cyclone (TC research has focused on the Atlantic Basin, continental socio-ecological systems, affluent regions where the resilience attributes of the human element differ from that of the of majority the world’s population, and organized countries where research and relief capacities are among the best worldwide. I contend that this collective international bias minimizes the usefulness of global TC research in light of global change forecasts, which predict increased frequency of intense TCs. Moreover, paleoecological studies indicate ecosystem resilience following a TC is greatly increased within habitats that experienced a prior history of frequent TCs. When these retrospective and future visions are connected, science-based analysis of the influences of climate change on TC disturbance argues for an increase in contemporary research on TCs of developing island nations in the western Pacific where TCs are already relatively frequent. Otherwise the current research trajectory may further widen the disconnect between best available science and future management decisions.

  14. Satellite radiance data assimilation for binary tropical cyclone cases over the western North Pacific

    Science.gov (United States)

    Choi, Yonghan; Cha, Dong-Hyun; Lee, Myong-In; Kim, Joowan; Jin, Chun-Sil; Park, Sang-Hun; Joh, Min-Su

    2017-06-01

    A total of three binary tropical cyclone (TC) cases over the Western North Pacific are selected to investigate the effects of satellite radiance data assimilation on analyses and forecasts of binary TCs. Two parallel cycling experiments with a 6 h interval are performed for each binary TC case, and the difference between the two experiments is whether satellite radiance observations are assimilated. Satellite radiance observations are assimilated using the Weather Research and Forecasting Data Assimilation (WRFDA)'s three-dimensional variational (3D-Var) system, which includes the observation operator, quality control procedures, and bias correction algorithm for radiance observations. On average, radiance assimilation results in slight improvements of environmental fields and track forecasts of binary TC cases, but the detailed effects vary with the case. When there is no direct interaction between binary TCs, radiance assimilation leads to better depictions of environmental fields, and finally it results in improved track forecasts. However, positive effects of radiance assimilation on track forecasts can be reduced when there exists a direct interaction between binary TCs and intensities/structures of binary TCs are not represented well. An initialization method (e.g., dynamic initialization) combined with radiance assimilation and/or more advanced DA techniques (e.g., hybrid method) can be considered to overcome these limitations.

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

    Science.gov (United States)

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

    2014-12-01

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

  16. Midtropospheric frontogenesis associated with antecedent indirect precipitation ahead of tropical cyclones over the Korean Peninsula

    Directory of Open Access Journals (Sweden)

    Eun-Hyuk Baek

    2015-07-01

    Full Text Available On the Korean Peninsula (KP, heavy rainfall often precedes the landfall of a tropical cyclone (TC. This rainfall is called antecedent indirect precipitation (AIP, because it occurs well beyond the effective radius of the TC. The present study examines the statistical characteristics and physical mechanism of the AIP produced by TCs that influenced the KP during the period 1993–2004. Composite analyses demonstrate that the AIP events were accompanied by midtropospheric frontogenesis due to the TC-mid-latitude environment interaction. When an approaching TC encountered an approaching mid-latitude upper-level trough, this encounter resulted in confluent and deformed flows at the mid-level by the combination of westerlies from the trough and southerlies from the TC. The delicate balance of horizontal winds related to the two systems at the mid-level led to the midtropospheric frontogenesis to the north of the KP. The frontogenetic feature related to the AIP was in marked contrast to those of the remote rainfall event over the KP and the predecessor rainfall event over the United States suggested by previous studies. Quasi-geostrophic analysis demonstrates that the midtropospheric front induced thermally direct circulation, which led to ascending motion over the KP. Consequently, the midtropospheric front helped to intensify the AIP, together with the convective instability that was amplified by the transport of warm and moist air along the conduit between the TC and subtropical high.

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

    Science.gov (United States)

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

    2014-12-01

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

  18. A Top-Down Pathway to Secondary Eyewall Formation in Simulated Tropical Cyclones

    Science.gov (United States)

    Tyner, Bryce; Zhu, Ping; Zhang, Jun A.; Gopalakrishnan, Sundararaman; Marks, Frank; Tallapragada, Vijay

    2018-01-01

    Idealized and real-case simulations conducted using the Hurricane Weather Research and Forecasting (HWRF) model demonstrate a "top-down" pathway to secondary eyewall formation (SEF) for tropical cyclones (TCs). For the real-case simulations of Hurricane Rita (2005) and Hurricane Edouard (2014), a comparison to observations reveals the timing and overall characteristics of the simulated SEF appear realistic. An important control of the top-down pathway to SEF is the amount and radial-height distribution of hydrometeors at outer radii. Examination into the simulated hydrometeor particle fall speed distribution reveals that the HWRF operational microphysics scheme is not producing the lightest hydrometeors, which are likely present in observed TCs and are most conducive to being advected from the primary eyewall to the outer rainband region of the TC. Triggering of SEF begins with the fallout of hydrometeors at the outer radii from the TC primary eyewall, where penetrative downdrafts resulting from evaporative cooling of precipitation promote the development of local convection. As the convection-induced radial convergence that is initially located in the midtroposphere extends downward into the boundary layer, it results in the eruption of high entropy air out of the boundary layer. This leads to the rapid development of rainband convection and subsequent SEF via a positive feedback among precipitation, convection, and boundary layer processes.

  19. Impacts of the Lower Stratosphere on the Development of Intense Tropical Cyclones

    Directory of Open Access Journals (Sweden)

    Zachary Moon

    2017-07-01

    Full Text Available This study examines potential impacts of the lower stratosphere on the development and the inner-core structure of intense tropical cyclones (TCs. By initializing the Hurricane Weather Research and Forecasting (HWRF model with different monthly averaged sounding profiles in the Northwestern Pacific and the North Atlantic basins, it is shown that the lower stratosphere layer (LSL can impose a noticeable influence on the TC structure and development via formation of an extra warm core near the tropopause along with a thin layer of inflow in the LSL at the high-intensity limit. Specifically, a lower tropopause level allows for higher TC intensity and a more distinct double warm core structure. Likewise, a weaker LSL stratification also corresponds to a warmer upper-level core and higher intensity. Of further significance is that the double warm core formation is more sensitive to tropopause variations in the Northwestern Pacific basin than those in the North Atlantic basin, given the same sea surface temperature. The results suggest that variations in tropopause level and LSL stratification could be an important factor that is responsible for the long-term variability of TC intensity.

  20. Impact of Ocean Warming on Tropical Cyclone Size and Its Destructiveness.

    Science.gov (United States)

    Sun, Yuan; Zhong, Zhong; Li, Tim; Yi, Lan; Hu, Yijia; Wan, Hongchao; Chen, Haishan; Liao, Qianfeng; Ma, Chen; Li, Qihua

    2017-08-15

    The response of tropical cyclone (TC) destructive potential to global warming is an open issue. A number of previous studies have ignored the effect of TC size change in the context of global warming, which resulted in a significant underestimation of the TC destructive potential. The lack of reliable and consistent historical data on TC size limits the confident estimation of the linkage between the observed trend in TC size and that in sea surface temperature (SST) under the background of global climate warming. A regional atmospheric model is used in the present study to investigate the response of TC size and TC destructive potential to increases in SST. The results show that a large-scale ocean warming can lead to not only TC intensification but also TC expansion. The TC size increase in response to the ocean warming is possibly attributed to the increase in atmospheric convective instability in the TC outer region below the middle troposphere, which facilitates the local development of grid-scale ascending motion, low-level convergence and the acceleration of tangential winds. The numerical results indicate that TCs will become stronger, larger, and unexpectedly more destructive under global warming.

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

    Science.gov (United States)

    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.

  2. A prediction scheme of tropical cyclone frequency based on lasso and random forest

    Science.gov (United States)

    Tan, Jinkai; Liu, Hexiang; Li, Mengya; Wang, Jun

    2017-07-01

    This study aims to propose a novel prediction scheme of tropical cyclone frequency (TCF) over the Western North Pacific (WNP). We concerned the large-scale meteorological factors inclusive of the sea surface temperature, sea level pressure, the Niño-3.4 index, the wind shear, the vorticity, the subtropical high, and the sea ice cover, since the chronic change of these factors in the context of climate change would cause a gradual variation of the annual TCF. Specifically, we focus on the correlation between the year-to-year increment of these factors and TCF. The least absolute shrinkage and selection operator (Lasso) method was used for variable selection and dimension reduction from 11 initial predictors. Then, a prediction model based on random forest (RF) was established by using the training samples (1978-2011) for calibration and the testing samples (2012-2016) for validation. The RF model presents a major variation and trend of TCF in the period of calibration, and also fitted well with the observed TCF in the period of validation though there were some deviations. The leave-one-out cross validation of the model exhibited most of the predicted TCF are in consistence with the observed TCF with a high correlation coefficient. A comparison between results of the RF model and the multiple linear regression (MLR) model suggested the RF is more practical and capable of giving reliable results of TCF prediction over the WNP.

  3. A study of ocean spray lubrication effect on tropical cyclone intensity

    Science.gov (United States)

    Rastigejev, Yevgenii; Lin, Yuh-Lang

    2008-10-01

    It has been shown recently (Barenblatt, et al., 2005) that the presence of water droplets in the vortex of tropical cyclone (TC) leads to a significant reduction in turbulent intensity and consequently to a sharp flow acceleration. The developed theory has been extended by considering different mechanisms of ocean spray production, positive feedback of wind acceleration, different turbulence closure models and some other contributing factors. The sensitivity of ocean spray lubrication effect to the theoretical model has been investigated. A series of numerical experiments with an ideal hurricane model have been performed. The simulations have been run with and without spray for different theoretical models. An effort to develop a proper spray parameterization based on the theoretical consideration and the results of numerical experiments is undertaken. Consequently we will incorporate the spray parameterization in the realistic Weather Research and Forecast (WRF) numerical model in order to improve the accuracy of TC intensity prediction. This work is supported by a grant from the National Oceanic and Atmospheric Administration, Educational Partnership Program under the cooperative agreement NA06OAR4810187.

  4. Observational Rainfall change analysis of tropical cyclones making landfall in Zhejiang of China

    Science.gov (United States)

    Yu, Z.

    2012-04-01

    Being accompanied by torrential rains, tropical cyclones (TCs) are the most devastating natural disasters in Chinese coastal provinces, inflicting huge losses in property and human life. But most of these casualties occurred in Zhejiang and 140 people were killed in Zhejiang Province annually, even though the average number of TCs made landfall in Zhejiang is only 0.9 and it is much lower than that for Hainan, Guangdong and Fujian provinces. In other words, Zhejiang Provinces is more vulnerable to landfalling TCs than Fujian and Guangdong. Despite the significant impacts of torrential rainfall from TCs at landfall, predicting rainfall associated with TCs is a major operational challenge. Therefore, better understanding the rainfall change and the associated reasons during TCs landfall is an important step toward disaster prevention and mitigation. This study will examine the spatial distribution of TCs rainfall during making landfall in Zhejiang Province of China. We will use rainfall observations, vertical wind shear data, and TC motion data to examine the relationship between the storm motion, environmental vertical wind shear, and TC rainfall asymmetry. We will also investigate how these relationships vary for different stages when TCs made landfall in Zhejiang. Detailed advances will be shown in the oral presentation.

  5. Global composites of surface wind speeds in tropical cyclones based on a 12 year scatterometer database

    Science.gov (United States)

    Klotz, Bradley W.; Jiang, Haiyan

    2016-10-01

    A 12 year global database of rain-corrected satellite scatterometer surface winds for tropical cyclones (TCs) is used to produce composites of TC surface wind speed distributions relative to vertical wind shear and storm motion directions in each TC-prone basin and various TC intensity stages. These composites corroborate ideas presented in earlier studies, where maxima are located right of motion in the Earth-relative framework. The entire TC surface wind asymmetry is down motion left for all basins and for lower strength TCs after removing the motion vector. Relative to the shear direction, the motion-removed composites indicate that the surface wind asymmetry is located down shear left for the outer region of all TCs, but for the inner-core region it varies from left of shear to down shear right for different basin and TC intensity groups. Quantification of the surface wind asymmetric structure in further stratifications is a necessary next step for this scatterometer data set.

  6. Assessing Current and Future Freshwater Flood Risk from North Atlantic Tropical Cyclones via Insurance Claims

    Science.gov (United States)

    Czajkowski, Jeffrey; Villarini, Gabriele; Montgomery, Marilyn; Michel-Kerjan, Erwann; Goska, Radoslaw

    2017-02-01

    The most recent decades have witnessed record breaking losses associated with U.S. landfalling tropical cyclones (TCs). Flood-related damages represent a large portion of these losses, and although storm surge is typically the main focus in the media and of warnings, much of the TC flood losses are instead freshwater-driven, often extending far inland from the landfall locations. Despite this actuality, knowledge of TC freshwater flood risk is still limited. Here we provide for the first time a comprehensive assessment of the TC freshwater flood risk from the full set of all significant flood events associated with U.S. landfalling TCs from 2001 to 2014. We find that the areas impacted by freshwater flooding are nearly equally divided between coastal and inland areas. We determine the statistical relationship between physical hazard and residential economic impact at a community level for the entire country. These results allow us to assess the potential future changes in TC freshwater flood risk due to changing climate pattern and urbanization in a more heavily populated U.S. Findings have important implications for flood risk management, insurance and resilience.

  7. Data Normalization to Accelerate Training for Linear Neural Net to Predict Tropical Cyclone Tracks

    Directory of Open Access Journals (Sweden)

    Jian Jin

    2015-01-01

    Full Text Available When pure linear neural network (PLNN is used to predict tropical cyclone tracks (TCTs in South China Sea, whether the data is normalized or not greatly affects the training process. In this paper, min.-max. method and normal distribution method, instead of standard normal distribution, are applied to TCT data before modeling. We propose the experimental schemes in which, with min.-max. method, the min.-max. value pair of each variable is mapped to (−1, 1 and (0, 1; with normal distribution method, each variable’s mean and standard deviation pair is set to (0, 1 and (100, 1. We present the following results: (1 data scaled to the similar intervals have similar effects, no matter the use of min.-max. or normal distribution method; (2 mapping data to around 0 gains much faster training speed than mapping them to the intervals far away from 0 or using unnormalized raw data, although all of them can approach the same lower level after certain steps from their training error curves. This could be useful to decide data normalization method when PLNN is used individually.

  8. Re-Framing the World Wide Web

    Science.gov (United States)

    Black, August

    2011-01-01

    The research presented in this dissertation studies and describes how technical standards, protocols, and application programming interfaces (APIs) shape the aesthetic, functional, and affective nature of our most dominant mode of online communication, the World Wide Web (WWW). I examine the politically charged and contentious battle over browser…

  9. Welcome to the World-Wide Web.

    Science.gov (United States)

    Davis, Philip

    1995-01-01

    World Wide Web (WWW) is a multimedia, globally distributed, client/server information system based on hypertext. WWW browser software (Mosaic, Cello, and Samba) allows users to navigate hypertext documents via the Internet. Libraries are taking advantage of the fact that hypertext linked documents can be easily and inexpensively shared. (JMV)

  10. Happy 20th Birthday, World Wide Web!

    CERN Multimedia

    2009-01-01

    On 13 March CERN celebrated the 20th anniversary of the World Wide Web. Check out the video interview with Web creator Tim Berners-Lee and find out more about the both the history and future of the Web. To celebrate CERN also launched a brand new website, CERNland, for kids.

  11. Internet and The World Wide Web

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 2. Internet and The World Wide Web. Neelima Shrikhande. General Article Volume 2 Issue 2 February 1997 pp 64-74. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/002/02/0064-0074 ...

  12. Precipitation stable isotope analysis for exploring temporal characteristics of tropical cyclones: A case study in Hong Kong

    Science.gov (United States)

    Chun, K. P.; Klaus, J.

    2016-12-01

    Hurricanes (or typhoons) play an important role in tropical and subtropical synoptic climates. Although increasing global temperatures in the 20th and 21st centuries are proposed to be linked to changing characteristics of hurricanes, results from previous studies are contradictory and changing environmental conditions affecting hurricanes are somewhat poorly conceptualised. In this investigation, stable precipitation isotope data are used to explore how hurricane properties change with variations of monsoon and regional climate patterns (e.g. the El Niño-Southern Oscillations). As a case study, a new approach using precipitation isotopes to analyse Hong Kong tropical cyclone time series is proposed. First, the variance of precipitation stable isotopes is decomposed to understand the influence of monsoons, southern oscillations and other regional climate conditions on Hong Kong precipitation isotopic signatures. Then, using decomposed precipitation isotope results, a frequency analysis of tropical hurricanes is performed to identify climatic controls and quantify their effects. Results from this study are expected to be valuable because they will provide an example which illustrates how local isotope data can be linked to the regional climate patterns. A framework to investigate Asian tropical cyclone change using stable precipitation isotopes is also proposed.

  13. Synoptic and dynamical analysis of subtropical cyclone Anita (2010) and its potential for tropical transition over the South Atlantic Ocean

    Science.gov (United States)

    Dias Pinto, João. Rafael; Reboita, Michelle Simões; da Rocha, Rosmeri Porfírio

    2013-10-01

    cyclogenesis and tropical transitions (TT) over the South Atlantic Ocean only received attention after the first documented Hurricane Catarina occurred close to the southern Brazilian coast in March 2004. However, due to the lack of studies in this part of the Atlantic Ocean, it is still unclear what the main environmental conditions and dynamical processes associated with TT or even subtropical cyclogenesis are over the region. This study presents a synoptic and dynamical analysis of the subtropical cyclone Anita which occurred in March 2010 near the Brazilian coast. This system started as a pure subtropical cyclone, evolved to a condition favorable to TT, later developed into a cold-core structure, and decayed as an extratropical cyclone. During the period favorable for TT, the turbulent heat fluxes (latent plus sensible) from the ocean decreased, and Anita started interacting with another extratropical disturbance, preventing the TT to happen. This interaction, in turn, increased the vertical wind shear, allowed the extratropical transition to occur, and promoted the westward displacement of Anita to colder waters, thus decreasing the turbulent heat fluxes. The results suggest that the combination of a dipole blocking pattern aloft, with contribution from barotropic energy conversions, and strong turbulent fluxes is an important ingredient for tropical storm development. Hybrid storms in such environmental conditions can be one form of precursors of hurricanes over the South Atlantic.

  14. Variability of tropical cyclone rapid intensification in the North Atlantic and its relationship with climate variations

    Science.gov (United States)

    Wang, Chunzai; Wang, Xidong; Weisberg, Robert H.; Black, Michael L.

    2017-02-01

    The paper uses observational data from 1950 to 2014 to investigate rapid intensification (RI) variability of tropical cyclones (TCs) in the North Atlantic and its relationships with large-scale climate variations. RI is defined as a TC intensity increase of at least 15.4 m/s (30 knots) in 24 h. The seasonal RI distribution follows the seasonal TC distribution, with the highest number in September. Although an RI event can occur anywhere over the tropical North Atlantic (TNA), there are three regions of maximum RI occurrence: (1) the western TNA of 12°N-18°N and 60°W-45°W, (2) the Gulf of Mexico and the western Caribbean Sea, and (3) the open ocean southeast and east of Florida. RI events also show a minimum value in the eastern Caribbean Sea north of South America—a place called a hurricane graveyard due to atmospheric divergence and subsidence. On longer time scales, RI displays both interannual and multidecadal variability, but RI does not show a long-term trend due to global warming. The top three climate indices showing high correlations with RI are the June-November ENSO and Atlantic warm pool indices, and the January-March North Atlantic oscillation index. It is found that variabilities of vertical wind shear and TC heat potential are important for TC RI in the hurricane main development region, whereas relative humidity at 500 hPa is the main factor responsible for TC RI in the eastern TNA. However, the large-scale oceanic and atmospheric variables analyzed in this study do not show an important role in TC RI in the Gulf of Mexico and the open ocean southeast and east of Florida. This suggests that other factors such as small-scale changes of oceanic and atmospheric variables or TC internal processes may be responsible for TC RI in these two regions. Additionally, the analyses indicate that large-scale atmospheric and oceanic variables are not critical to TC genesis and formation; however, once a tropical depression forms, large-scale climate

  15. Variability of tropical cyclone rapid intensification in the North Atlantic and its relationship with climate variations

    Science.gov (United States)

    Wang, Chunzai; Wang, Xidong; Weisberg, Robert H.; Black, Michael L.

    2017-12-01

    The paper uses observational data from 1950 to 2014 to investigate rapid intensification (RI) variability of tropical cyclones (TCs) in the North Atlantic and its relationships with large-scale climate variations. RI is defined as a TC intensity increase of at least 15.4 m/s (30 knots) in 24 h. The seasonal RI distribution follows the seasonal TC distribution, with the highest number in September. Although an RI event can occur anywhere over the tropical North Atlantic (TNA), there are three regions of maximum RI occurrence: (1) the western TNA of 12°N-18°N and 60°W-45°W, (2) the Gulf of Mexico and the western Caribbean Sea, and (3) the open ocean southeast and east of Florida. RI events also show a minimum value in the eastern Caribbean Sea north of South America—a place called a hurricane graveyard due to atmospheric divergence and subsidence. On longer time scales, RI displays both interannual and multidecadal variability, but RI does not show a long-term trend due to global warming. The top three climate indices showing high correlations with RI are the June-November ENSO and Atlantic warm pool indices, and the January-March North Atlantic oscillation index. It is found that variabilities of vertical wind shear and TC heat potential are important for TC RI in the hurricane main development region, whereas relative humidity at 500 hPa is the main factor responsible for TC RI in the eastern TNA. However, the large-scale oceanic and atmospheric variables analyzed in this study do not show an important role in TC RI in the Gulf of Mexico and the open ocean southeast and east of Florida. This suggests that other factors such as small-scale changes of oceanic and atmospheric variables or TC internal processes may be responsible for TC RI in these two regions. Additionally, the analyses indicate that large-scale atmospheric and oceanic variables are not critical to TC genesis and formation; however, once a tropical depression forms, large-scale climate

  16. Possible relationship between NAO and tropical cyclone genesis frequency in the western North Pacific

    Science.gov (United States)

    Choi, Jae-Won; Cha, Yumi

    2017-03-01

    This study examined a strong positive correlation between the North Atlantic Oscillation (NAO) index during June and the total tropical cyclone (TC) genesis frequency in the western North Pacific during July and August. To investigate a possible cause for this relation, the mean difference between highest positive NAO years and lowest negative NAO years was analyzed by dividing into when the El Niño and La Niña years were included and when the El Niño and La Niña years were not included. When the El Niño and La Niña years were included, for positive NAO years, the TCs mostly occurred in the northwestern region of tropical and subtropical western Pacific, and showed a pattern that migrate from the sea northeast of the Philippines, pass the East China Sea, and move toward the mid-latitudes of East Asia. In contrast, for negative NAO years, the TCs mostly occurred in the southeastern region of tropical and subtropical western Pacific, and showed a pattern that migrate westward from the sea southeast of the Philippines, pass the South China Sea, and move toward the southern coast of China and Indochinese peninsula. These two different TC migration patterns affect the recurving location of TC, and for positive NAO years, the recurving of TC was averagely found to take place in the further northeast. In addition, the migration patterns also affect the TC intensity, and the TCs of positive NAO years had stronger intensity than the TCs of negative NAO years as sufficient energy can be absorbed from the ocean while moving north in the mid-latitudes of East Asia. The TCs of negative NAO years showed weak intensity as they weaken or disappear shortly while landing on the southern coast of China and Indochinese peninsula. On the other hand, the above result of analysis is also similarly observed when the El Niño and La Niña years were not included.

  17. Remote Sensing of Tropical Cyclones: Applications from Microwave Radiometry and Global Navigation Satellite System Reflectometry

    Science.gov (United States)

    Morris, Mary

    Tropical cyclones (TCs) are important to observe, especially over the course of their lifetimes, most of which is spent over the ocean. Very few in situ observations are available. Remote sensing has afforded researchers and forecasters the ability to observe and understand TCs better. Every remote sensing platform used to observe TCs has benefits and disadvantages. Some remote sensing instruments are more sensitive to clouds, precipitation, and other atmospheric constituents. Some remote sensing instruments are insensitive to the atmosphere, which allows for unobstructed observations of the ocean surface. Observations of the ocean surface, either of surface roughness or emission can be used to estimate ocean surface wind speed. Estimates of surface wind speed can help determine the intensity, structure, and destructive potential of TCs. While there are many methods by which TCs are observed, this thesis focuses on two main types of remote sensing techniques: passive microwave radiometry and Global Navigation Satellite System reflectometry (GNSS-R). First, we develop and apply a rain rate and ocean surface wind speed retrieval algorithm for the Hurricane Imaging Radiometer (HIRAD). HIRAD, an airborne passive microwave radiometer, operates at C-band frequencies, and is sensitive to rain absorption and emission, as well as ocean surface emission. Motivated by the unique observing geometry and high gradient rain scenes that HIRAD typically observes, a more robust rain rate and wind speed retrieval algorithm is developed. HIRAD's observing geometry must be accounted for in the forward model and retrieval algorithm, if high rain gradients are to be estimated from HIRAD's observations, with the ultimate goal of improving surface wind speed estimation. Lastly, TC science data products are developed for the Cyclone Global Navigation Satellite System (CYGNSS). The CYGNSS constellation employs GNSS-R techniques to estimate ocean surface wind speed in all precipitating

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

    Science.gov (United States)

    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

  19. Community relations via the World Wide Web

    Energy Technology Data Exchange (ETDEWEB)

    Gossman, D.G.; Gossman, S.E. [Gossman Consulting, Inc., Hampshire, IL (United States)

    1998-12-31

    The Internet or world wide web provides an unprecedented opportunity to communicate with the public and improve community relations. By providing a Virtual Plant Tour{trademark} and important environmental plans and reports on line, industry can short circuit the rumor mill and provide information to the local community, regulatory officials, and the world at large. Audience, content, maintenance, design considerations and costs are all examined.

  20. A simple model for post-landfall intensity changes of tropical cyclone ...

    Indian Academy of Sciences (India)

    approach, the Genetic Algorithm, has been used to develop the above empirical equation using data .... We used Genetic Algorithms (GA) to derive empir- ..... Coast. Table 3. Accuracy of best freeform model for cyclones in different categories. Cyclone. Intensity. Number MAE category range of cases. (kt). Depression. <27 kt.

  1. Tropical cyclones over north Indian Ocean during El-Nino Modoki years

    Digital Repository Service at National Institute of Oceanography (India)

    Sumesh, K.G.; RameshKumar, M

    significant impact of air–sea interaction processes like El-Nino and El-Nino Modoki on the cyclone activity over different ocean basins. The results suggest in most cases, El-Nino events suppress the formation of cyclones over various basins. A recent study...

  2. Assessing extreme sea levels due to tropical cyclones in the Atlantic basin

    Science.gov (United States)

    Muis, Sanne; Lin, Ning; Verlaan, Martin; Winsemius, Hessel; Vatvani, Deepak; Ward, Philip; Aerts, Jeroen

    2017-04-01

    Tropical cyclones (TCs), including hurricanes and typhoons, are characterised by high wind speeds and low pressure and cause dangerous storm surges in coastal areas. Over the last 50 years, storm surge incidents in the Atlantic accounted for more than 1,000 deaths in the United Stated. Recent flooding disasters, such as Hurricane Katrina in New Orleans in 2005 and, Hurricane Sandy in New York in 2012, exemplify the significant TC surge risk in the United States. In this contribution, we build on Muis et al. (2016), and present a new modelling framework to simulate TC storm surges and estimate their probabilities for the Atlantic basin. In our framework we simulate the surge levels by forcing the Global Tide and Surge Model (GTSM) with wind and pressure fields from TC events. To test the method, we apply it to historical storms that occurred between 1988 and 2015 in the Atlantic Basin. We obtain high-resolution meteorological forcing by applying a parametric hurricane model (Holland 1980; Lin and Chavas 2012) to the TC extended track data set (Demuth et al. 2006; updated), which describes the position, intensity and size of the historical TCs. Preliminary results show that this framework is capable of accurately reproducing the main surge characteristics during past events, including Sandy and Katrina. While the resolution of GTSM is limited for local areas with a complex bathymetry, the overall performance of the model is satisfactory for the basin-scale application. For an accurate assessment of risk to coastal flooding in the Atlantic basin it is essential to provide reliable estimates of surge probabilities. However, the length of observed TC tracks is too short to accurately estimate the probabilities of extreme TC events. So next steps are to statistically extend the observed record to many thousands of years (e.g., Emanuel et al. 2006), in order to force GTSM with a large number of synthetic storms. Based on these synthetic simulations, we would be able to

  3. Modeling Tropical Cyclone Induced Inland Flooding at Tar Pamlico River Basin of North Carolina

    Science.gov (United States)

    Tang, Qianhong

    Landfalling tropical cyclones often produce heavy precipitation and result in river and flash floods. Such floods can not only cause loss of human lives and properties, but also lead to ecological disasters in the affected watershed areas, estuaries and coastal waters. In order to better understand and simulate large coastal watershed hydrology and hydro-meteorological processes associated with tropical cyclones (TC) - induced inland flooding, the Weather Research and Forecasting (WRF) model and the Annualized Agricultural Nonpoint Source Pollution Model (AnnAGNPS) have been employed in this study. The study focuses on four major hydro-meteorological identities and their interactions: 1) previous rainfall events, 2) synoptic atmospheric environment, 3) landfalling hurricane, and 4) surface and ground water hydrology. The research is divided into two parts. Part one focuses on the investigation of the impacts of previous rainfall events on watershed surface runoff while part two studies the impacts of the synoptic atmospheric environment on landfalling hurricanes and the resulting effect on surface runoff. Hurricane Floyd was chosen in this study as a special case because it produced massive flooding as a result of the combined effects of previous rainfall events from Hurricane Dennis and the synoptic atmospheric environment. The modeling results indicate that the AnnAGNPS model performs well in predicting the total amount of watershed runoff. However Muskingum channel routing is needed for AnnAGNPS to improve the hydrographs of flow discharge during hurricane events. Sensitivity analysis of soil saturated hydrological conductivity (Ks) indicates that both base flow and event total runoff are sensitive to Ks. Base flow increases as Ks increases when K s ≥15 m/day, but slightly decreases when K s > 15 m/day which is out of assumption of linear relationship from Darcy's law. Peak runoff exponentially decreases as Ks increases. The results show that without the

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

    Science.gov (United States)

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

    2009-12-01

    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) has recently begun to support an effort to identify and evaluate hurricane mitigation strategies through Project HURRMIT ([http://www.ofcm.noaa.gov/ihc09/Presentations/Session10/s10-01Woodley.ppt]). Using a decision analytic framing and FEMA's HAZUS-MH MR3 damage model (http://www.fema.gov/plan/prevent/hazus/]), this paper asks, how sure must one be that an intervention will reduce TC damages before choosing to undertake a program of modification? The analysis is formulated in probabilistic terms, and assesses net benefits. In contrast to a much earlier application of decision analysis to TC-modification (Howard et al., 1972) , this work uses census data on the value of property at risk, and prior distributions on changing storm behavior based on data from hurricanes approaching the east coast of Florida since 1953. Even before considering both issues of liability that may arise from the fact that a modified storm is no longer "an act of God" as well as unforeseen environmental consequences, our results suggest that while TC modification techniques will likely alter TC behavior, one will have to be significantly more confident of the predictability and effectiveness of modification methods before their use can be justified. This work is supported by the Climate Decision Making Center through a cooperative agreement between the National Science Foundation (SES-0345798) and Carnegie Mellon University.

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

    Science.gov (United States)

    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

  6. Uncertainty and feasibility of dynamical downscaling for modeling tropical cyclones for storm surge simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Taraphdar, Sourav; Wang, Taiping; Ruby Leung, L.; Grear, Molly

    2016-08-22

    This paper presents a modeling study conducted to evaluate the uncertainty of a regional model in simulating hurricane wind and pressure fields, and the feasibility of driving coastal storm surge simulation using an ensemble of region model outputs produced by 18 combinations of three convection schemes and six microphysics parameterizations, using Hurricane Katrina as a test case. Simulated wind and pressure fields were compared to observed H*Wind data for Hurricane Katrina and simulated storm surge was compared to observed high-water marks on the northern coast of the Gulf of Mexico. The ensemble modeling analysis demonstrated that the regional model was able to reproduce the characteristics of Hurricane Katrina with reasonable accuracy and can be used to drive the coastal ocean model for simulating coastal storm surge. Results indicated that the regional model is sensitive to both convection and microphysics parameterizations that simulate moist processes closely linked to the tropical cyclone dynamics that influence hurricane development and intensification. The Zhang and McFarlane (ZM) convection scheme and the Lim and Hong (WDM6) microphysics parameterization are the most skillful in simulating Hurricane Katrina maximum wind speed and central pressure, among the three convection and the six microphysics parameterizations. Error statistics of simulated maximum water levels were calculated for a baseline simulation with H*Wind forcing and the 18 ensemble simulations driven by the regional model outputs. The storm surge model produced the overall best results in simulating the maximum water levels using wind and pressure fields generated with the ZM convection scheme and the WDM6 microphysics parameterization.

  7. Simulation of tropical cyclone activity over the western North Pacific based on CMIP5 models

    Science.gov (United States)

    Shen, Haibo; Zhou, Weican; Zhao, Haikun

    2017-09-01

    Based on the Coupled Model Inter-comparison Project 5 (CMIP5) models, the tropical cyclone (TC) activity in the summers of 1965-2005 over the western North Pacific (WNP) is simulated by a TC dynamically downscaling system. In consideration of diversity among climate models, Bayesian model averaging (BMA) and equal-weighed model averaging (EMA) methods are applied to produce the ensemble large-scale environmental factors of the CMIP5 model outputs. The environmental factors generated by BMA and EMA methods are compared, as well as the corresponding TC simulations by the downscaling system. Results indicate that BMA method shows a significant advantage over the EMA. In addition, impacts of model selections on BMA method are examined. To each factor, ten models with better performance are selected from 30 CMIP5 models and then conduct BMA, respectively. As a consequence, the ensemble environmental factors and simulated TC activity are similar with the results from the 30 models' BMA, which verifies the BMA method can afford corresponding weight for each model in the ensemble based on the model's predictive skill. Thereby, the existence of poor performance models will not particularly affect the BMA effectiveness and the ensemble outcomes are improved. Finally, based upon the BMA method and downscaling system, we analyze the sensitivity of TC activity to three important environmental factors, i.e., sea surface temperature (SST), large-scale steering flow, and vertical wind shear. Among three factors, SST and large-scale steering flow greatly affect TC tracks, while average intensity distribution is sensitive to all three environmental factors. Moreover, SST and vertical wind shear jointly play a critical role in the inter-annual variability of TC lifetime maximum intensity and frequency of intense TCs.

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

    Science.gov (United States)

    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.

  9. Favorable environments for the occurrence of overshooting tops in tropical cyclones

    Science.gov (United States)

    Sun, Liangxiao; Zhuge, Xiaoyong; Wang, Yuan

    2017-04-01

    Based on Multifunctional Transport Satellite data and the infrared window-texture detection algorithm, the level of overshooting top (OT) activity within a tropical cyclone (TC), which is defined as the hourly mean number of OT occurrence, was statistically investigated in the western North Pacific basin for the period 2005-12. Based on the level of OT activity, the samples were divided into OT and non-OT cases or high-activity-OT (HA-OT) and low-activity-OT (LA-OT) cases. The differences in large-scale environmental variables between OT (HA-OT) and non-OT (LA-OT) cases were examined 12 hours prior to the OT occurrence. Statistical analysis showed that environmental differences did exist between the OT and non-OT cases. The OTs were more skewed towards the early stage of the TC life cycle, and mostly concentrated in low latitudes. Meanwhile, a sufficiently deep warm-water layer, large temperature difference between the upper- and lower-level troposphere, large humidity at the middle and upper levels, and large atmospheric instability, were favorable for OT occurrence. The differences in large-scale environmental characteristics between HA-OTs and LA-OTs were not as significant as those between OTs and non-OTs, but the HA-OT samples tended to occur when the vertical shear was weak and the TC intensity was low. Finally, statistical models were designed to predict the OT and HA-OT. When at least three OT (HA-OT) predictor thresholds were satisfied, the Peirce skill score reached a maximum value of 0.49 (0.30).

  10. Tropical cyclone influence on the long-term variability of Philippine summer monsoon onset

    Science.gov (United States)

    Kubota, Hisayuki; Shirooka, Ryuichi; Matsumoto, Jun; Cayanan, Esperanza O.; Hilario, Flaviana D.

    2017-12-01

    The long-term variability of Philippine summer monsoon onset from 1903 to 2013 was investigated. The onset date is defined by daily rainfall data at eight stations in the northwestern Philippines. Summer monsoons tended to start earlier in May after the mid-1990s. Other early onset periods were found during the 1900s, 1920s, and 1930s, and an interdecadal variability of summer monsoon onset was identified. Independent surface wind data observed by ships in the South China Sea (SCS) revealed prevailing westerly wind in May during the early monsoon onset period. To identify atmospheric structures that trigger Philippine summer monsoon onset, we focused on the year 2013, conducting intensive upper-air observations. Tropical cyclone (TC) Yagi traveled northward in the Philippine Sea (PS) in 2013 and triggered the Philippine monsoon onset by intensifying moist low-level southwesterly wind in the southwestern Philippines and intensifying low-level southerly wind after the monsoon onset in the northwestern Philippines. The influence of TC was analyzed by the probability of the existence of TC in the PS and the SCS since 1951, which was found to be significantly correlated with the Philippine summer monsoon onset date. After the mid-1990s, early monsoon onset was influenced by active TC formation in the PS and the SCS. However, the role of TC activity decreased during the late summer monsoon periods. In general, it was found that TC activity in the PS and the SCS plays a key role in initiating Philippine summer monsoon onset. [Figure not available: see fulltext.

  11. Sea-state Dependence of Sea Surface Temperature Cooling and its Feedback on Tropical Cyclone Intensity

    Science.gov (United States)

    Blair, A.; Reichl, B. G.; Ginis, I.; Hara, T.; Thomas, B.

    2016-02-01

    Air-sea momentum and heat fluxes underneath tropical cyclones (TCs) are important controls on storm intensity. Increased upper ocean mixing due to TC winds can upwell cooler waters to the surface, reducing the heat flux from the ocean and weakening the storm. Therefore, improved representation of the wind forcing and the resulting sea surface temperature cooling in coupled ocean-wave-atmosphere models can help increase the accuracy of intensity predictions. However, the impact of surface waves (sea state) on these processes is not fully understood. The three most significant sea state dependent effects on upper ocean processes are the Coriolis-Stokes forcing, the air-sea flux budget (effect of growing/decaying surface waves), and the Langmuir turbulence (enhancement of the upper ocean mixing due to surface waves). In this study we focus on the first two effects. To examine these two effects a comparison is made using a series of idealized storms, with a range of translation speeds, with individual and combined implementations of these two components in a fully coupled ocean-wave-atmosphere model. The Princeton Ocean Model is used with a 1/12th degree resolution and 23 half-sigma levels and an initial temperature profile based on the Gulf of Mexico climatology. It is coupled to the WaveWatch III wave model, also at 1/12th degree resolution. The atmospheric component is the NOAA/GFDL hurricane model, which has 42 vertical levels and a three-level nested mesh. The inner two meshes are 1/18th and 1/6th degree resolution, with the finer inside the coarser, and move with the storm. It is found that both the Coriolis-stokes forcing and the sea state dependent air-sea flux modify the magnitude and the spatial distribution of the sea surface cooling, and that the combined effect may significantly modify the storm intensity predictions.

  12. Observation of Tropical Cyclone-Induced Shallow Water Currents in Taiwan Strait

    Science.gov (United States)

    Shen, Junqiang; Qiu, Yun; Zhang, Shanwu; Kuang, Fangfang

    2017-06-01

    The data from three stations equipped with Acoustic Doppler Current Profilers (ADCPs) deployed in the shallow water of the Taiwan Strait (TWS) were used to study the shallow coastal ocean response to five quasi-continuous tropical cyclone (TC) events in the late summer 2006. We revealed that, in the forced stage, when the large and strong TC (Bilis) transited, the geostrophic currents were formed which dominated the whole event, while the strong but relatively small one (Saomai) or the weak one (Bopha) primarily leaded to the generation of Ekman currents. In the relaxation stage, the barotropic subinertial waves and/or the baroclinic near-inertial oscillations (NIOs) were triggered. Typically, during the transit of the Saomai, subinertial waves were induced which demonstrated a period of 2.8-4.1 days and a mean alongshore phase velocity of 14.9 ± 3.2 m/s in the form of free-barotropic continental shelf waves. However, the NIOs are only notable in the area in which the water column is stably stratified and also where the wind stress is dominated by the clockwise component and accompanied by high-frequency (near-inertial) variations. We also demonstrated that, due to the damping effects, the nonlinear wave-wave interaction (e.g., between NIO and semidiurnal tide in our case), together with the well-known bottom friction, led to the rapid decay of the observed TC-induced near-inertial currents, giving a typical e-folding time scale of 1-3 inertial periods. Moreover, such nonlinear wave-wave interaction was even found to play a major role during the spring tide in TWS.

  13. Towards a full representation of tropical cyclones in a global reanalysis of extreme sea levels

    Science.gov (United States)

    Muis, S.; Verlaan, M.; Lin, N.; Winsemius, H.; Vatvani, D.; Ward, P.; Aerts, J.

    2016-12-01

    Tropical cyclones (TCs), including hurricanes and typhoons, are characterised by high wind speeds and low pressure, and cause dangerous storm surges in coastal areas. Recent disasters like the flooding of New Orleans in 2005 due to Hurricane Katrina and of New York in 2012 due to Hurricane Sandy exemplify the significant TC risk in the United States. In this contribution, we present a new framework to model TC storm surges and probabilities at the Atlantic basin- and, ultimately, global scales. This works builds on the work of Muis et al. (2016), which presented the first dynamically-derived reanalysis dataset of storm surges that covers the entire world's coastline (GTSR dataset). Surge levels for the period 1979-2014 were simulated by forcing the Global Surge and Tide Model (GTSM) with wind speed and atmospheric pressure from the ERA-Interim reanalysis. There is generally a good agreement between simulated and observed sea level extremes in extra-tropical regions; however for areas prone to TCs there is a severe underestimation of extremes. For example, the maximum surge levels during Hurricane Katrina in New Orleans exceeded 8 m, whilst the GTSM surge levels in that area do not exceed 2-3 m. Hence, due to the coarse grid resolution, the strong intensities of TCs are not fully captured in ERA-Interim. Furthermore, the length of ERA-Interim data set, like other reanalysis datasets, is too short to estimate the probabilities of extreme TC events in a reliable way. For accurate risk assessments it is essential to improve the representation of TCs in these global reanalysis of extreme sea levels. First, we need a higher resolution of meteorological forcing, which can be modelled with input from the observed best track data. Second, we need to statistically extend the observed record to many thousands of years. We will present the first results of these steps for the east coast of the United States. We will validate the GTSM model forced with best track data using

  14. Interannual variability of the South Pacific Convergence Zone and implications for tropical cyclone genesis

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Emmanuel M. [IRD/UPMC/CNRS/MNHN, Laboratoire d' Oceanographie et du Climat: Experimentation et Approches Numeriques (LOCEAN), Paris (France); UPMC, LOCEAN/IPSL, Paris Cedex 05 (France); Lengaigne, Matthieu [IRD/UPMC/CNRS/MNHN, Laboratoire d' Oceanographie et du Climat: Experimentation et Approches Numeriques (LOCEAN), Paris (France); National Institute of Oceanography, Goa (India); Menkes, Christophe E. [IRD/UPMC/CNRS/MNHN, Laboratoire d' Oceanographie et du Climat: Experimentation et Approches Numeriques (LOCEAN), Paris (France); Institut de Recherche pour le Developpement, Noumea (New Caledonia); Jourdain, Nicolas C. [Institut de Recherche pour le Developpement, Noumea (New Caledonia); Marchesiello, Patrick [Institut de Recherche pour le Developpement, Noumea (New Caledonia); CNES/CNRS/UPS/IRD, Laboratoire d' Etudes en Geophysique et Oceanographie Spatiale (LEGOS), Toulouse (France); Madec, Gurvan [IRD/UPMC/CNRS/MNHN, Laboratoire d' Oceanographie et du Climat: Experimentation et Approches Numeriques (LOCEAN), Paris (France); National Oceanographic Centre, Southampton (United Kingdom)

    2011-05-15

    The interannual variability of the South Pacific Convergence Zone (SPCZ) and its influence on tropical cyclone (TC) genesis in the South Pacific are investigated using observations and ERA40 reanalysis over the 1979-2002 period. In austral summer, the SPCZ displays four typical structures at interannual timescales. The first three are characterized by a diagonal orientation of the SPCZ and account for 85% of the summer seasons. One is close to climatology and the other two exhibit a 3 northward or southward departure from the SPCZ climatological position. In contrast, the fourth one, that only encompasses three austral summer seasons (the extreme 1982/1983 and 1997/1998 El Nino events and the moderate 1991/1992 El Nino event), displays very peculiar behaviour where the SPCZ largely departs from its climatological position and is zonally oriented. Variability of the western/central Pacific equatorial sea surface temperature (SST) is shown to modulate moisture transport south of the equator, thereby strongly constraining the location of the SPCZ. The SPCZ location is also shown to strongly modulate the atmospheric circulation variability in the South Pacific with specific patterns for each class. However, independently of its wide year-to-year excursions, the SPCZ is always collocated with the zero relative vorticity at low levels while the maximum vorticity axis lies 6 to the south of the SPCZ position. This coherent atmospheric organisation in the SPCZ region is shown to constrain tropical cyclogenesis to occur preferentially within 10 south of the SPCZ location as this region combines all the large-scale atmospheric conditions that favour the breeding of TCs. This analysis also reveals that cyclogenesis in the central Pacific (in the vicinity of French Polynesia) only occurs when the SPCZ displays a zonal orientation while this observation was previously attributed to El Nino years in general. Different characteristics of El Nino Southern Oscillation (ENSO

  15. The combined risk of extreme tropical cyclone winds and storm surges along the U.S. Gulf of Mexico Coast

    Science.gov (United States)

    Trepanier, J. C.; Yuan, J.; Jagger, T. H.

    2017-03-01

    Tropical cyclones, with their nearshore high wind speeds and deep storm surges, frequently strike the United States Gulf of Mexico coastline influencing millions of people and disrupting offshore economic activities. The combined risk of occurrence of tropical cyclone nearshore wind speeds and storm surges is assessed at 22 coastal cities throughout the United States Gulf of Mexico. The models used are extreme value copulas fitted with margins defined by the generalized Pareto distribution or combinations of Weibull, gamma, lognormal, or normal distributions. The statistical relationships between the nearshore wind speed and storm surge are provided for each coastal city prior to the copula model runs using Spearman's rank correlations. The strongest significant relationship between the nearshore wind speed and storm surge exists at Shell Beach, LA (ρ = 0.67), followed by South Padre Island, TX (ρ = 0.64). The extreme value Archimedean copula models for each city then provide return periods for specific nearshore wind speed and storm surge pairs. Of the 22 cities considered, Bay St. Louis, MS, has the shortest return period for a tropical cyclone with at least a 50 ms-1 nearshore wind speed and a 3 m surge (19.5 years, 17.1-23.5). The 90% confidence intervals are created by recalculating the return periods for a fixed set of wind speeds and surge levels using 100 samples of the model parameters. The results of this study can be utilized by policy managers and government officials concerned with coastal populations and economic activity in the Gulf of Mexico.

  16. Numerical modeling of storm surges in the coast of Mozambique: the cases of tropical cyclones Bonita (1996) and Lisette (1997)

    Science.gov (United States)

    Bié, Alberto José; de Camargo, Ricardo; Mavume, Alberto Francisco; Harari, Joseph

    2017-11-01

    The coast of Mozambique is often affected by storms, particularly tropical cyclones during summer or sometimes midlatitude systems in the southern part. Storm surges combined with high freshwater discharge can drive huge coastal floods, affecting both urban and rural areas. To improve the knowledge about the impact of storm surges in the coast of Mozambique, this study presents the first attempt to model this phenomenon through the implementation of the Princeton Ocean Model (POM) in the Southwestern Indian Ocean domain (SWIO; 2-32°S, 28-85°E) using a regular grid with 1/6° of spatial resolution and 36 sigma levels. The simulation was performed for the period 1979-2010, and the most interesting events of surges were related to tropical cyclones Bonita (1996) and Lisette (1997) that occurred in the Mozambique Channel. The results showed that the model represented well the amplitude and phase of principal lunar and solar tidal constituents, as well as it captured the spatial pattern and magnitudes of SST with slight positive bias in summer and negative bias in winter months. In terms of SSH, the model underestimated the presence of mesoscale eddies, mainly in the Mozambique Channel. Our results also showed that the atmospheric sea level pressure had a significant contribution to storm heights during the landfall of the tropical cyclones Bonita (1996) and Lisette (1997) in the coast of Mozambique contributing with about 20 and 16% of the total surge height for each case, respectively, surpassing the contribution of the tide-surge nonlinear interactions by a factor of 2.

  17. Promoting and supporting PBL interests world wide

    DEFF Research Database (Denmark)

    Enemark, Stig; Kolmos, Anette; Moesby, Egon

    2006-01-01

    of projects world wide focusing on institutional change toward a more student centred, project organised, and problem based approach to learning. The Centre is also establishing a UCPBL Global Network on Problem Based Learning in order to facilitate better access to and co-operation within the PBL area.......-Based Learning (PBL) in Engineering Education, an increasing number of universities and engineering schools throughout the world are seeking consultancy and cooperation with Aalborg University. The establishment of UCPBL is therefore a timely opportunity to merge the efforts into one organisational structure...

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

    Science.gov (United States)

    Lewis, Daniel B.; Finkelstein, David B.; Grissino-Mayer, Henri D.; Mora, Claudia I.; Perfect, Edmund

    2011-06-01

    Tree rings afford the temporal resolution needed to characterize extreme weather events such as tropical cyclones, their frequency and variability. External factors such as soil water isotopic variability, soil heterogeneity, and/or stand disturbance affect the isotopic composition of individual trees in a stand, resulting in inaccuracies in the record. Single-tree isotope chronologies should be tested against multiple-tree chronologies to determine whether individual trees sufficiently characterize tropical cyclone variability. Eight individual trees from two sites in Big Thicket National Preserve were analyzed to evaluate whether they synchronously record tropical cyclone events. The ability of individual isotope models to capture an event was low (≤50%), and individual trees did not always record similar events. A composite chronology from the Turkey Creek Unit identified 5 false positive years and missed five storms. The composite chronology from the Big Sandy Creek Unit identified 5 false positives and missed four storms. All but 3 false positive years were characterized by above average precipitation that followed below average precipitation in the previous year. This mimics the negative isotopic excursion expected from tropical cyclones. Another year (1991) was coincident with a strong El Niño event, resulting in a shift in the dominant moisture source for the Texas Gulf Coast. Drought conditions occurred in years where storms were missed, which dampened the 18O-depleted signal associated with tropical cyclones. These data show that the number of trees is critical for properly characterizing tropical cyclone frequency through time, especially for periods prior to reliable instrumental records.

  19. An estimation of water origins in the vicinity of a tropical cyclone's center and associated dynamic processes

    Science.gov (United States)

    Takakura, Toshinari; Kawamura, Ryuichi; Kawano, Tetsuya; Ichiyanagi, Kimpei; Tanoue, Masahiro; Yoshimura, Kei

    2018-01-01

    To clarify the time evolution of water origins in the vicinity of a tropical cyclone (TC)'s center, we have simulated Typhoon Man-yi (July 2007) in our case study, using an isotopic regional spectral model. The model results confirm that the replacement of water origins occurs successively as the TC develops and migrates northward over the western North Pacific. It is confirmed that, in this case, a significant proportion of total precipitable water around the cyclone center comes from external regions rather than the underlying ocean during the mature stage of a TC. Similar features can also be seen in the proportion of each oceanic origin to total condensation. Indian Ocean, South China Sea, and Maritime Continent water vapors begin to increase gradually at the developing stage and reach their peak at the decay stage when the TC approaches southwestern Japan. These remote ocean vapors are transported to the east of the cyclone via the moisture conveyor belt, a zone characterized by distinct low-level moisture flux that stretches from the Indian Ocean to the TC, and are further supplied into the inner region of the TC by inflow within the boundary layer associated with its secondary circulation. Since it takes time to undergo these two dynamic processes, the delayed influence of remote ocean vapors on the TC appears to become evident during the mature stage.

  20. Are greenhouse gas signals of Northern Hemisphere winter extra-tropical cyclone activity dependent on the identification and tracking algorithm?

    Energy Technology Data Exchange (ETDEWEB)

    Ulbrich, Uwe; Grieger, Jens [Freie Univ. Berlin (Germany). Inst. of Meteorology; Leckebusch, Gregor C. [Birmingham Univ. (United Kingdom). School of Geography, Earth and Environmental Sciences] [and others

    2013-02-15

    For Northern Hemisphere extra-tropical cyclone activity, the dependency of a potential anthropogenic climate change signal on the identification method applied is analysed. This study investigates the impact of the used algorithm on the changing signal, not the robustness of the climate change signal itself. Using one single transient AOGCM simulation as standard input for eleven state-of-the-art identification methods, the patterns of model simulated present day climatologies are found to be close to those computed from re-analysis, independent of the method applied. Although differences in the total number of cyclones identified exist, the climate change signals (IPCC SRES A1B) in the model run considered are largely similar between methods for all cyclones. Taking into account all tracks, decreasing numbers are found in the Mediterranean, the Arctic in the Barents and Greenland Seas, the mid-latitude Pacific and North America. Changing patterns are even more similar, if only the most severe systems are considered: the methods reveal a coherent statistically significant increase in frequency over the eastern North Atlantic and North Pacific. We found that the differences between the methods considered are largely due to the different role of weaker systems in the specific methods. (orig.)

  1. Analysing motives behind willingness to pay for improving early warning services for tropical cyclones in Vietnam

    National Research Council Canada - National Science Library

    Nguyen, Thanh Cong; Robinson, Jackie

    2015-01-01

    ...), this study elicited values for an improved cyclone warning service in Vietnam. To examine motives or reasons behind respondents' WTP, respondents were requested to allocate 10 points among different types of values, including self...

  2. A possible mechanism of the impact of atmosphere-ocean interaction on the activity of tropical cyclones affecting China

    Science.gov (United States)

    Ren, Fumin; Bai, Lina; Wu, Guoxiong; Wang, Zaizhi; Wang, Yuan

    2012-07-01

    In this study, tropical cyclone data from China Meteorological Administration (CMA) and the ECMWF reanalysis data for the period 1958-2001 was used to propose a possible mechanism for the impacts of air-sea interaction on the activity of tropical cyclones (TCs) affecting China. The frequency of TCs affecting China over past 40 years has trended downward, while during the same period, the air-sea interaction in the two key areas of the Pacific region has significantly weakened. Our diagnoses and simulations suggest that air-sea interactions in the central North Pacific tropics and subtropics (Area 1) have an important role in adjusting typhoon activities in the Northwest Pacific in general, and especially in TC activity affecting China. On the contrary, impacts of the air-sea interaction in the eastern part of the South Pacific tropics (Area 2) were found to be rather limited. As both observational analysis and modeling studies show that, in the past four decades and beyond, the weakening trend of the latent heat released from Area 1 matched well with the decreasing Northwest Pacific TC frequency derived from CMA datasets. Results also showed that the weakening trend of latent heat flux in the area was most likely due to the decreasing TC frequency over the Northwest Pacific, including those affecting China. Although our preliminary analysis revealed a possible mechanism through which the air-sea interaction may adjust the genesis conditions for TCs, which eventually affect China, other relevant questions, such as how TC tracks and impacts are affected by these trends, remain unanswered. Further in-depth investigations are required.

  3. Predictability of Seasonal Precipitation Intensities Associated with Tropical Cyclones and Disturbances in Indo-China Region

    Science.gov (United States)

    Revel, M.; Utsumi, N.; Yoshikawa, S.; Kanae, S.

    2016-12-01

    Summer Monsoon precipitation provide support for the livelihood of the people of Southeast Asia where the population density is very high. Monsoon precipitation shows high variation in seasonal and yearly time scales affecting daily life of the people in the regions such Indo-China peninsula where most of the countries depend on agricultural economy. Predictability of seasonal extreme events such as flooding and droughts by different climatic conditions will enhance the ability to mitigate the risk of natural disasters in Indo-China peninsula. In addition lower tropospheric (850hPa) wind flow pattern is very useful in understanding the seasonal variability of Southeastern Asian Summer Monsoon. Furthermore summer monsoon in the Indo-China peninsula is strongly influenced by the local wind-terrain-precipitation interaction. Recently a set of Monsoon Indices has been developed by several researches, Indo China Monsoon Indices (ICMIs) as a representation of lower tropospheric wind flow patterns around Southeast Asian. On the other hand different precipitation providing weather systems vary according to the global position and local weather system. Responses of ICMIs to different precipitation providing weather systems may vary in temporal and spatial scales. Hence the seasonal responses of differentiated precipitation with ICMIs in Indo-China peninsula are being investigated. Objective detection methods are been adopted in order to identify the locations of tropical cyclones (TCs), and westward propagating disturbances (WDs) using a Japanese 25-year ReAnalysis data and the Global Precipitation Climatology Project One-Degree Daily data is differentiated into TCs, and WDs related precipitation. TCs contribute highly over the east coast of Indo China peninsula where WDs contributed all over land area of Indo-China peninsula but more towards Bay of Bengal. Correlations and regressions suggest that the indices which is calculated using the wind patterns, situated west of

  4. Long term Changes in Flooding and Heavy Rainfall Associated with North Atlantic Tropical Cyclones

    Science.gov (United States)

    Aryal, Y.; Villarini, G.; Zhang, W.; Vecchi, G. A.

    2016-12-01

    Flooding associated with North Atlantic tropical cyclones (TCs) are one of the costliest weather disasters in the continental United States, claiming a large toll in terms of fatalities and economic damage. Despite these large impacts, very little attention has been paid to the temporal changes in TC-flood hazard and to the possible connections with climate. In this study, we focus on long-term U.S. Geological Survey (USGS) stream gages with at least 50 years of data ending no earlier than 2010 and located over most of the continental United States, east of the Rocky Mountains. Analyses are based on annual maxima (AMs) and Peaks-Over-Threshold (POTs). We associate a flood peak to a TC if the stream gage is located within 500 km from the center of circulation of the storms and it happens within a time window of seven days. Moreover, to account for potential non stationarities in the flood peak records and for differences due to drainage area, we compute the flood ratio, defined as the ratio between the TC-flood and the 2-year flood peak computed with respect to moving ten-year time window. We find that TCs contribute to large fractions of AMs and POTs over Florida ( 30-40%), with their influence that decreases as we move inland. We do not detect statistically significant increasing or decreasing trends in flood ratio or in the frequency of TC floods. Beside the examination of temporal changes in TC-flooding, we also examine the role played by the North Atlantic Oscillation (NAO) and El Niño - Southern Oscillation (ENSO) in controlling the frequency and magnitude of these events. Overall, TC floods tend to be more likely during the negative phase of NAO. On the other hand, the effects of ENSO tend to vary in space. Overall, NAO and ENSO do not seem to play a large role in controlling the frequency and magnitude of TC flooding. Similar analyses will be performed using TC-rainfall, comparing and contrasting what found for TC-flooding.

  5. High resolution modeling of tropical cyclones-ocean interactions in the South-West Indian Ocean.

    Science.gov (United States)

    Chanut, J.; Samson, G.; Giordani, H.; Barbary, D.; Drillet, Y.

    2016-02-01

    The ocean surface can cool by several degrees during the passage of a tropical cyclone (TC) due to the extreme winds associated with. This cooling decreases the ocean-to-atmosphere heat and moisture supply which can modulate the TC intensity. Hence, atmospheric models need an accurate description of the sea surface temperature (SST) under TCs to correctly predict their intensities. This SST evolution and its feedback on the TC evolution can only be captured by ocean-atmosphere coupled models. In order to evaluate this potential benefit on TC forecasts in the South West Indian Ocean, Mercator-Ocean has developed a new coupled regional model based on the Meteo-France operational atmospheric model AROME and the NEMO ocean model. Exchanges between the two models are handled by the OASIS3 coupler. AROME is initialized and forced at its lateral boundaries with ALADIN 10km-resolution 6-hourly analysis and is integrated during 96 hours at 2.5km convective-resolving resolution. NEMO is initialized and forced with global 1/4° oceanic analyses performed weekly at Mercator-Ocean and is integrated at 1/12° eddy-resolving resolution. An ensemble of 25 coupled simulations and 25 atmospheric-only (forced) simulations based on 5 different TCs over the 2008-2013 seasons are then computed to explore the sensitivity of the TC hindcast to the SST. The ensemble is generated by varying the initial simulation time with a 6-hours step. A clear improvement of the SST evolution under the TCs is observed in the coupled simulations when compared to satellite data. This SST difference directly impacts turbulent latent and sensible heat fluxes spatial distribution and intensities, which lead to different intensification rates in the coupled and the forced simulations. The intensity hindcast mean error is significantly reduced in the coupled ensemble for hindcast ranges extending from 36h up to 96h. A statistical analysis confirms the robustness of this intensity hindcast improvement achieved

  6. Towards a climatology of tropical cyclone morphometric structures using a newly standardized passive microwave satellite dataset

    Science.gov (United States)

    Cossuth, J.; Hart, R. E.

    2013-12-01

    The structure of a tropical cyclone (TC) is a spatial representation of its organizational pattern and distribution of energy acquisition and release. Physical processes that react to both the external environment and its own internal dynamics manifest themselves in the TC shape. This structure depicts a specific phase in the TC's meteorological lifecycle, reflecting its past and potentially constraining its future development. For a number of reasons, a thorough objective definition of TC structures and an intercomparison of their varieties have been neglected. This lack of knowledge may be a key reason why TC intensity forecasts, despite numerical model improvements and theoretical advances, have been stagnant in recent years relative to track forecasts. Satellite microwave imagers provide multiple benefits in discerning TC structure, but compiling a research quality data set has been problematic due to several inherent technical and logistical issues. While there are multiple satellite sensors that incorporate microwave frequencies, inter-comparison between such sensors is limited by the different available channels, spatial resolutions, and calibration metrics between satellites, all of which provide inconsistencies in resolving TC structural features. To remedy these difficulties, a global archive of TCs as measured by all available US satellite microwave sensors is compiled and standardized. Using global historical best track data, TC microwave data is retrieved from the Defense Meteorological Satellite Program (DMSP) series (including all SSM/I and SSMIS), TMI, AMSR-E, and WindSat sensors. Standardization between sensors for each TC overpass are performed, including: 1) Recalibration of data from the 'ice scattering' channels to a common frequency (89GHz); 2) Resampling the DMSP series to a higher resolution using the Backus-Gilbert technique; and 3) Re-centering the TC center more precisely using the ARCHER technique (Wimmers and Velden 2010) to analyze the

  7. The Improved NRL Tropical Cyclone Monitoring System with a Unified Microwave Brightness Temperature Calibration Scheme

    Directory of Open Access Journals (Sweden)

    Song Yang

    2014-05-01

    Full Text Available The near real-time NRL global tropical cyclone (TC monitoring system based on multiple satellite passive microwave (PMW sensors is improved with a new inter-sensor calibration scheme to correct the biases caused by differences in these sensor’s high frequency channels. Since the PMW sensor 89 GHz channel is used in multiple current and near future operational and research satellites, a unified scheme to calibrate all satellite PMW sensor’s ice scattering channels to a common 89 GHz is created so that their brightness temperatures (TBs will be consistent and permit more accurate manual and automated analyses. In order to develop a physically consistent calibration scheme, cloud resolving model simulations of a squall line system over the west Pacific coast and hurricane Bonnie in the Atlantic Ocean are applied to simulate the views from different PMW sensors. To clarify the complicated TB biases due to the competing nature of scattering and emission effects, a four-cloud based calibration scheme is developed (rain, non-rain, light rain, and cloudy. This new physically consistent inter-sensor calibration scheme is then evaluated with the synthetic TBs of hurricane Bonnie and a squall line as well as observed TCs. Results demonstrate the large TB biases up to 13 K for heavy rain situations before calibration between TMI and AMSR-E are reduced to less than 3 K after calibration. The comparison stats show that the overall bias and RMSE are reduced by 74% and 66% for hurricane Bonnie, and 98% and 85% for squall lines, respectively. For the observed hurricane Igor, the bias and RMSE decrease 41% and 25% respectively. This study demonstrates the importance of TB calibrations between PMW sensors in order to systematically monitor the global TC life cycles in terms of intensity, inner core structure and convective organization. A physics-based calibration scheme on TC’s TB corrections developed in this study is able to significantly reduce the

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

    Energy Technology Data Exchange (ETDEWEB)

    Iizuka, Satoshi; Matsuura, Tomonori [National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Ibaraki (Japan)

    2008-06-15

    A high-resolution (T213) coupled ocean-atmosphere general circulation model (CGCM) has been used to examine the relationship between El Nino/Southern Oscillation (ENSO) and tropical cyclone (TC) activity over the western North Pacific (WNP). The model simulates ENSO-like events similar to those observed, though the amplitude of the simulated Nino34 sea surface temperature (SST) anomaly is twice as large as observed. In El Nino (La Nina) years, the annual number of model TCs in the southeast quadrant of the WNP increases (decreases), while it decreases (increases) in the northwest quadrant. In spite of the significant difference in the mean genesis location of model TCs between El Nino and La Nina years, however, there is no significant simultaneous correlation between the annual number of model TCs over the entire WNP and model Nino34 SST anomalies. The annual number of model TCs, however, tends to decrease in the years following El Nino, relating to the development of anticyclonic circulation around the Philippine Sea in response to the SST anomalies in the central and eastern equatorial Pacific. Furthermore, it seems that the number of model TCs tends to increase in the years before El Nino. It is also shown that the number of TCs moving into the East Asia is fewer in October of El Nino years than La Nina years, related to the anomalous southward shift of mid-latitude westerlies, though no impact of ENSO on TC tracks is found in other months. It is found that model TCs have longer lifetimes due to the southeastward shift of mean TC genesis location in El Nino years than in La Nina years. As the result of longer fetch of TCs over warm SST, model TCs appear to be more intense in El Nino years. These relationships between ENSO and TC activity in the WNP are in good agreement with observational evidence, suggesting that a finer-resolution CGCM may become a powerful tool for understanding interannual variability of TC activity. (orig.)

  9. Relationships between convective asymmetry, imbalance and intensity in numerically simulated tropical cyclones

    Directory of Open Access Journals (Sweden)

    David A. Schecter

    2013-09-01

    Full Text Available This article examines the relationships between convective asymmetry (CA, imbalance and intensity in tropical cyclones (TCs that emerge from random winds on the periodic f-plane in a cloud-system-resolving numerical model. The model is configured with warm-rain microphysics and includes a basic parameterisation of long-wave radiation. Within the simulation set, the sea-surface temperature ranges from 26 to 32°C, and the Coriolis parameter f ranges from 10−5 to 10−4 s−1. The number of TCs that develop in a simulation increases rapidly with f and ranges from 1 to 18. Taken together, the simulations provide a diverse spectrum of vortices that can be used for a meaningful statistical study.Consistent with earlier studies, mature TCs with minimal asymmetry are found to have maximum wind speeds greater than the classic theoretical value derived by Emanuel under the assumptions of gradient-wind and hydrostatic balance. In a statistical sense, it is found that the degree of superintensity with respect to balance theory reliably decays with an increasing level of inner-core CA. It is verified that a more recent version of axisymmetric steady-state theory, revised to incorporate imbalance, provides a good approximation for the maximum (azimuthally averaged azimuthal wind speed V max when CA is relatively weak. More notably, this theory for axisymmetric vortices maintains less than 10% error as CA becomes comparable in magnitude to the symmetric component of inner-core convection. Above a large but finite threshold of CA, axisymmetric steady-state theory generally over-predicts V max. The underachievement of TCs in this parameter regime is shown to coincide with substantial violation of the theoretical assumption of slantwise convective neutrality in the main updraft of the basic state. Of further interest, a reliable curve-fit is obtained for the anticorrelation between a simple measure of CA and V max normalised to an estimate of its balanced

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

    Science.gov (United States)

    Yonekura, Emmi; Hall, Timothy M.

    2011-01-01

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

  11. Statistical analysis and a case study of tropical cyclones that trigger the onset of the South China Sea summer monsoon.

    Science.gov (United States)

    Huangfu, Jingliang; Huang, Ronghui; Chen, Wen

    2017-10-06

    This paper addresses whether a tropical cyclone can trigger the onset of the South China Sea (SCS) summer monsoon (SM). We conducted a statistical analysis of tropical cyclones (TCs) generated over the western North Pacific (WNP) between late-April and May. The results showed that there were cases in which TCs were generated before the onset of the SCSSM, accounting for 43.2% of the TCs generated during this season. This study examined a representative case, Super Typhoon Chanchu (0601), which was determined to be influential in the onset of the SCSSM. With a northwestward track, Chanchu brought strong convection and westerly winds to the SCS on 12 May, which triggered the intrusion of the southwesterly winds from the Bay of Bengal and the eastward retreat of the western Pacific subtropical high. Super Typhoon Chanchu provides an example in which a TC triggered the onset of the SCSSM. The negative correlation between the onset date of the SCSSM and the number of TCs generated over the WNP used to be interpreted as the influence of the monsoon trough on TC genesis. This work provides a supplementary illustration that this relationship also includes the impact of TCs on the onset of the SCSSM.

  12. Nonbreaking wave-induced mixing in upper ocean during tropical cyclones using coupled hurricane-ocean-wave modeling

    Science.gov (United States)

    Aijaz, S.; Ghantous, M.; Babanin, A. V.; Ginis, I.; Thomas, B.; Wake, G.

    2017-05-01

    The effects of turbulence generated by nonbreaking waves have been investigated by testing and evaluating a new nonbreaking wave parameterization in a coupled hurricane-ocean-wave model. The MPI version of the Princeton Ocean Model (POM) with hurricane forcing is coupled with the WAVEWATCH-III (WW3) surface wave model. Hurricane Ivan is chosen as the test case due to its extreme intensity and availability of field data during its passage. The model results are validated against field observations of wave heights and sea surface temperatures (SSTs) from the National Data Buoy Centre (NDBC) during Hurricane Ivan and against limited in situ current and bottom temperature data. A series of numerical experiments is set up to examine the influence of the nonbreaking wave parameterization on the mixing of upper ocean. The SST response from the modeling experiments indicates that the nonbreaking wave-induced mixing leads to significant cooling of the SST and deepening of the mixed layer. It was found that the nondimensional constant b1 in the nonbreaking wave parameterization has different impacts on the weak and the strong sides of the storm track. A constant value of b1 leads to improved predictions on the strong side of the storm while a steepness-dependent b1 provides a better agreement with in situ observations on the weak side. A separate simulation of the intense tropical cyclone Olwyn in north-west Australia revealed the same trend for b1 on the strong side of the tropical cyclone.

  13. Impact of tropical cyclones on the evolution of the monsoon-driven upwelling system in the coastal waters of the northern South China Sea

    Science.gov (United States)

    Zheng, Binxin; Li, Yunhai; Li, Jiufa; Shu, Fangfang; He, Jia

    2017-12-01

    An upwelling system exists in the coastal waters of the northern South China Sea (NSCS), a region that is frequently affected by tropical cyclones in summer. This study investigates the evolution of the NSCS monsoon-driven upwelling system and the effects of the Talim and Doksuri tropical cyclones on the system using in situ observational data obtained at three mooring stations, one land-based meteorological station, and concurrent satellite remote sensing data for the NSCS coastal waters from May to July 2012. The results show that the occurrence and evolution of the upwelling system were mainly controlled by the Asian southwest monsoon, while the eastward current also made important contributions to the upwelling intensity. A decrease in the bottom water temperature and shifts in the along-shore and cross-shore currents were direct evidence of the establishment, existence, and recovery of this upwelling. Tropical cyclones have significant impacts on hydrodynamics and can thus influence the evolution of the NSCS upwelling system by changing the local wind and current fields. Variations in water level and local current systems impeded the development of upwelling during tropical cyclones Talim and Doksuri in the study area, which have low-frequency fluctuations of approximately 2-10 days. These variations were the results of the coupled interactions between local wind fields, coastal trapped waves, and other factors. The hydrodynamic environment of the marine water (including coastal upwelling system) rapidly recovered to normal sea conditions after each cyclone passed due to the relatively short duration of the impact of a tropical cyclone on the dynamic environment of the waters.

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

    Science.gov (United States)

    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

  15. World Wide Web Metasearch Clustering Algorithm

    Directory of Open Access Journals (Sweden)

    Adina LIPAI

    2008-01-01

    Full Text Available As the storage capacity and the processing speed of search engine is growing to keep up with the constant expansion of the World Wide Web, the user is facing an increasing list of results for a given query. A simple query composed of common words sometimes have hundreds even thousands of results making it practically impossible for the user to verify all of them, in order to identify a particular site. Even when the list of results is presented to the user ordered by a rank, most of the time it is not sufficient support to help him identify the most relevant sites for his query. The concept of search result clustering was introduced as a solution to this situation. The process of clustering search results consists of building up thematically homogenous groups from the initial list results provided by classic search tools, and using up characteristics present within the initial results, without any kind of predefined categories.

  16. World-Wide Web the information universe

    CERN Document Server

    Berners-Lee, Tim; Groff, Jean-Francois; Pollermann, Bernd

    1992-01-01

    Purpose - The World-Wide Web (W-3) initiative is a practical project designed to bring a global information universe into existence using available technology. This paper seeks to describe the aims, data model, and protocols needed to implement the "web" and to compare them with various contemporary systems. Design/methodology/approach - Since Vannevar Bush's article, men have dreamed of extending their intellect by making their collective knowledge available to each individual by using machines. Computers provide us two practical techniques for human-knowledge interface. One is hypertext, in which links between pieces of text (or other media) mimic human association of ideas. The other is text retrieval, which allows associations to be deduced from the content of text. The W-3 ideal world allows both operations and provides access from any browsing platform. Findings - Various server gateways to other information systems have been produced, and the total amount of information available on the web is...

  17. Promising prediction of the monsoon trough and its implication for tropical cyclone activity over the western North Pacific

    Science.gov (United States)

    Li, Chaofan; Lu, Riyu; Chen, Guanghua

    2017-07-01

    The monsoon trough (MT) is generally recognized as a feeding ground for tropical cyclones (TCs) over the western North Pacific (WNP). In view of the many challenges that remain in current seasonal TC forecasting, it would be a profound benefit to understand the predictability of variations in the MT and the implications of this for the seasonal prediction of TC activity. This study reveals that high predictability of the MT is shown by the current atmosphere-ocean coupled forecasting system, with the correlation coefficient being 0.84 for the model-ensemble prediction with observations from 1960 to 2005. This high predictability arises mainly from the tropical dipole sea surface temperature over the Maritime Continent and tropical Pacific Ocean, which favors convection around the warm pool and further excites the vorticity anomalies over the WNP. It is further found that good knowledge of the MT could provide promising prediction of TC activity over the WNP, including the occurrence and energy of TCs. The findings of this study suggest that coupling between the WNP circulation and tropical ocean acts as an important source of seasonal predictability in the WNP, and highlight the importance of the MT for seasonal prediction of TCs over the WNP.

  18. Tropical cyclones in two atmospheric (re)analyses and their response in two oceanic reanalyses

    Digital Repository Service at National Institute of Oceanography (India)

    Jourdain, N.C.; Barnier, B.; Ferry, N.; Vialard, J.; Menkes, C.E.; Lengaigne, M.; Parent, L.

    question that we address in this paper. A real-time estimate of the surface cooling below the cyclone could indeed be used as a proxy of the N.C. Jourdain et al. / Oceannegative feedback that the ocean exerts on the cyclone (not avail- able even from... Research Center, University of New South Wales, Sydney, Australia b Laboratoire de Glaciologie et Géophysique de l’Environnement (LGGE), Centre National de la Recherche Scientifique, Université de Grenoble, Grenoble, France c Laboratoire d’Océanographie et...

  19. Potential use of a regional climate model in seasonal tropical cyclone activity predictions in the western North Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Au-Yeung, Andie Y.M.; Chan, Johnny C.L. [City University of Hong Kong, Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, Kowloon, Hong Kong (China)

    2012-08-15

    This study investigates the potential use of a regional climate model in forecasting seasonal tropical cyclone (TC) activity. A modified version of Regional Climate Model Version 3 (RegCM3) is used to examine the ability of the model to simulate TC genesis and landfalling TC tracks for the active TC season in the western North Pacific. In the model, a TC is identified as a vortex satisfying several conditions, including local maximum relative vorticity at 850 hPa with a value {>=}450 x 10{sup -6} s{sup -1}, and the temperature at 300 hPa being 1 C higher than the average temperature within 15 latitude radius from the TC center. Tracks are traced by following these found vortices. Six-month ensemble (8 members each) simulations are performed for each year from 1982 to 2001 so that the climatology of the model can be compared to the Joint Typhoon Warning Center (JTWC) observed best-track dataset. The 20-year ensemble experiments show that the RegCM3 can be used to simulate vortices with a wind structure and temperature profile similar to those of real TCs. The model also reproduces tracks very similar to those observed with features like genesis in the tropics, recurvature at higher latitudes and landfall/decay. The similarity of the 500-hPa geopotential height patterns between RegCM3 and the European Centre for Medium-Range Weather Forecasts 40 Year Re-analysis (ERA-40) shows that the model can simulate the subtropical high to a large extent. The simulated climatological monthly spatial distributions as well as the interannual variability of TC occurrence are also similar to the JTWC data. These results imply the possibility of producing seasonal forecasts of tropical cyclones using real-time global climate model predictions as boundary conditions for the RegCM3. (orig.)

  20. Tropical cyclone effects on insect colonization and abundance in Puerto Rico

    Science.gov (United States)

    J. A. Torres

    1988-01-01

    The knowledge of the ways in which insects disperse is important in decisions concerning their control. The dispersal of insects aided by the wind cannot be regarded as accidental and occasional but as an adaptive feature of the phylum (Johnson and Bowden 1973). Due to its location, Puerto Rico is exposed to cyclone winds that can affect the colonization and abundance...

  1. Evaluating Atlantic Tropical Cyclone Track Error Distributions for Use in Probabilistic Forecasts of Wind Distribution

    Science.gov (United States)

    2010-09-01

    cyclones (TCs) routinely affect society, the economy , the environment, and military operations. Although coastal counties in the contiguous United... Yucatan Peninsula and was responsible for about 40 deaths across the Caribbean, with the largest tolls in Mexico and Haiti. Felix made landfall as a

  2. Bitcoin – the World-Wide Currency

    Directory of Open Access Journals (Sweden)

    Shuba Olena А.

    2017-11-01

    Full Text Available The article is aimed at researching bitcoin, the digital currency. It has been found that Bitcoin is a cryptocurrency, that is, the virtual money, which has no material equivalent. The history of creation and development of cryptocurrency was reviewed. There is a reduction in volatility, which guarantees the security of currency, as well as the increase in currency volume and the inability to estimate the profitability of bitcoins. The dynamics of the value of digital currency in US dollars over recent years has been analyzed. Improvement of attitude of many countries to the considered cryptocurrency, in particular the USA, Germany, Spain, Canada, Australia, Israel and Scandinavian countries has been identified. The reasons of Ukraine’s interest in Bitcoin have been considered. Possibilities of creation of cryptocurrency on the territory of Ukraine have been analyzed, i.e. cost of electricity for mining, the legal status of mining firms, and the attitude of the National Bank of Ukraine to the digital currency. It has been concluded that the recognition of Bitcoin by the world countries in the future will allow it to be granted the status of world-wide currency.

  3. Golden Jubilee Photos: World Wide Web

    CERN Multimedia

    2004-01-01

    At the end of the 1980s, the Internet was already a valuable tool to scientists, allowing them to exchange e-mails and to access powerful computers remotely. A more simple means of sharing information was needed, however, and CERN, with its long tradition of informatics and networking, was the ideal place to find it. Moreover, hundreds of scientists from all over the world were starting to work together on preparations for the experiments at the Large Electron-Positron (LEP) collider. In 1989, Tim Berners-Lee (see photo), a young scientist working at CERN, drafted a proposal for an information-management system combining the internet, personal computers and computer-aided document consultation, known as hypertext. In 1990 he was joined by Robert Cailliau and the weaving of the World Wide Web began in earnest, even though only two CERN computers were allocated to the task at the time. The Web subsequently underwent a steady expansion to include the world's main particle physics institutes. The Web was not the...

  4. Role of scale interactions in the abrupt change of tropical cyclone in autumn over the Western North Pacific

    Science.gov (United States)

    Hsu, Pang-Chi; Lee, Ting-Hui; Tsou, Chih-Hua; Chu, Pao-Shin; Qian, Yitian; Bi, Mingyu

    2017-01-01

    Tropical cyclone (TC) activity in autumn (September-November) over the western North Pacific experienced an abrupt change in 1998, which can be detected by the Bayesian change-point analysis. During the decade before the regime shift (1988-1997), the occurrence frequency of TC genesis increased significantly over the tropical western Pacific, where the seasonal cyclonic flow, intraseasonal oscillation (ISO) and synoptic-scale eddy (SSE) were all strengthened, compared to those observed in the decade after 1998 (1998-2007). The TC trajectories also exhibited spatial differences. During the active decade, the TCs had a higher probability to move westward into the Philippine Sea and the South China Sea, and recurved northeastward toward the east of Japan. Meanwhile, the northwestward propagating TCs approaching Taiwan and southeastern coast of China were reduced. To understand the role of mean flow-ISO-SSE interaction in the decadal changes of SSE and associated TC activity, we diagnosed a newly proposed SSE kinetic energy (KE) equation that separates the contributions of seasonal-mean circulation and ISO to the SSE. The results show that, during the active TC decade, the SSE obtained higher KE from both mean flow and ISO through eddy barotropic energy conversion when the enhanced SSE momentum flux interacted with the strengthened monsoon trough and vigorous ISO cyclonic anomaly over the western tropical Pacific. The increased SSE KE contributed positively to the increased TC genesis over the main genesis region (7.5°-20°N, 130°-170°E). It also benefited the growth of TCs over the Philippine Sea and the South China Sea during the active decade. The decadal change in TC frequency over the extratropics was related to the eddy baroclinic energy conversion instead of the barotropic conversion associated with scale interaction. During the active TC decade, SSE gained more (less) KE from the SSE available potential energy over the east of Japan (the East China Sea

  5. Role of scale interactions in the abrupt change of tropical cyclone in autumn over the Western North Pacific

    Science.gov (United States)

    Hsu, Pang-Chi; Lee, Ting-Hui; Tsou, Chih-Hua; Chu, Pao-Shin; Qian, Yitian; Bi, Mingyu

    2017-11-01

    Tropical cyclone (TC) activity in autumn (September-November) over the western North Pacific experienced an abrupt change in 1998, which can be detected by the Bayesian change-point analysis. During the decade before the regime shift (1988-1997), the occurrence frequency of TC genesis increased significantly over the tropical western Pacific, where the seasonal cyclonic flow, intraseasonal oscillation (ISO) and synoptic-scale eddy (SSE) were all strengthened, compared to those observed in the decade after 1998 (1998-2007). The TC trajectories also exhibited spatial differences. During the active decade, the TCs had a higher probability to move westward into the Philippine Sea and the South China Sea, and recurved northeastward toward the east of Japan. Meanwhile, the northwestward propagating TCs approaching Taiwan and southeastern coast of China were reduced. To understand the role of mean flow-ISO-SSE interaction in the decadal changes of SSE and associated TC activity, we diagnosed a newly proposed SSE kinetic energy (KE) equation that separates the contributions of seasonal-mean circulation and ISO to the SSE. The results show that, during the active TC decade, the SSE obtained higher KE from both mean flow and ISO through eddy barotropic energy conversion when the enhanced SSE momentum flux interacted with the strengthened monsoon trough and vigorous ISO cyclonic anomaly over the western tropical Pacific. The increased SSE KE contributed positively to the increased TC genesis over the main genesis region (7.5°-20°N, 130°-170°E). It also benefited the growth of TCs over the Philippine Sea and the South China Sea during the active decade. The decadal change in TC frequency over the extratropics was related to the eddy baroclinic energy conversion instead of the barotropic conversion associated with scale interaction. During the active TC decade, SSE gained more (less) KE from the SSE available potential energy over the east of Japan (the East China Sea

  6. The Structure of Vertical Wind Shear in Tropical Cyclone Environments: Implications for Forecasting and Predictability

    Science.gov (United States)

    Finocchio, Peter M.

    The vertical wind shear measured between 200 and 850 hPa is commonly used to diagnose environmental interactions with a tropical cyclone (TC) and to forecast the storm's intensity and structural evolution. More often than not, stronger vertical shear within this deep layer prohibits the intensification of TCs and leads to predictable asymmetries in precipitation. But such bulk measures of vertical wind shear can occasionally mislead the forecaster. In the first part of this dissertation, we use a series of idealized numerical simulations to examine how a TC responds to changing the structure of unidirectional vertical wind shear while fixing the 200-850-hPa shear magnitude. These simulations demonstrate a significant intensity response, in which shear concentrated in shallow layers of the lower troposphere prevents vortex intensification. We attribute the arrested development of TCs in lower-level shear to the intrusion of mid-level environmental air over the surface vortex early in the simulations. Convection developing on the downshear side of the storm interacts with the intruding air so as to enhance the downward flux of low-entropy air into the boundary layer. We also construct a two-dimensional intensity response surface from a set of simulations that sparsely sample the joint shear height-depth parameter space. This surface reveals regions of the two-parameter space for which TC intensity is particularly sensitive. We interpret these parameter ranges as those which lead to reduced intensity predictability. Despite the robust response to changing the shape of a sheared wind profile in idealized simulations, we do not encounter such sensitivity within a large set of reanalyzed TCs in the Northern Hemisphere. Instead, there is remarkable consistency in the structure of reanalyzed wind profiles around TCs. This is evident in the distributions of two new parameters describing the height and depth of vertical wind shear, which highlight a clear preference for

  7. Wind data collected by a fixed-wing aircraft in the vicinity of a tropical cyclone over the south China coastal waters

    Energy Technology Data Exchange (ETDEWEB)

    Chan, P.W.; Hon, K.K. [Hong Kong Observatory, Kowloon, HK (China); Foster, S. [Aventech Research Inc., Ontario (Canada)

    2011-06-15

    The fixed-wing aircraft of Government Flying Service of the Hong Kong Government has recently equipped with an upgraded meteorological measuring system. This system provides horizontal wind velocity components up to 90 m/s at an accuracy of 0.5 m/s for straight and level flight. Besides search and rescue (SAR) missions, this aircraft is also used for windshear and turbulence investigation flights at the Hong Kong International Airport. In a SAR operation in July 2009, the aircraft flew close to the eye of tropical cyclone Molave, when it was located at about 200 km to the east of Hong Kong over the south China coastal waters. The aircraft provided valuable information about the winds in association with Molave because aircraft reconnaissance for tropical cyclones is not carried out for South China Sea. Based on the aircraft measurements, the 1-second mean wind reached the maximum value of 88 knots at a height of 200 m above mean sea level. Assuming a power law with altitude with an exponent of 0.11 over open waters, the corresponding 1-second mean wind at a height of 10 m would be about 63 knots. The maximum 10-minute mean wind reached 69 knots with an average height of 260 m above mean sea level. The corresponding mean at 10 m would be about 48 knots. As such, based on the aircraft measurements (in which the aircraft might not fly into the areas of maximum winds associated with the tropical cyclone), Molave had at least a strength of tropical storm to severe tropical storm at the times of the measurements. Nowadays, the determination of the intensity of tropical cyclones over the South China Sea is normally based on remote sensing data only (e.g. radar and satellite observations). To the knowledge of the authors, the results presented in the paper are the first time that direct measurements of the winds near the centre of a tropical cyclone over the northern part of the South China Sea are made with an aircraft. Apart from the mean wind and gust, other properties

  8. Ionospheric precursors of the intensification of isolated tropical cyclones according to the IKB-1300 and Cosmos-1809 satellite data

    Science.gov (United States)

    Kostin, V. M.; Belyaev, G. G.; Boichev, B.; Trushkina, E. P.; Ovcharenko, O. Ya.

    2015-03-01

    The ionospheric parameters were analyzed, which made it possible to distinguish several successive stages in the development of isolated tropical cyclones (TCs). Data were taken from the Cosmos-1809 and Intercosmos Bulgaria-1300 satellites, which passed over several dozen TCs. The first stage of TC development consists of a sharp increase in altitudinal substorm activity caused by a tropical disturbance and depression. During this stage, plasma density caverns extending over several hundreds of kilometers are observed in the nighttime upper ionosphere a day before the formation of a tropical storm or even a category-I hurricane. The second stage, typical of TCs with intensities reaching categories I and II, is the displacement of a wide plasma density maximum in the upper ionosphere from the geomagnetic equator into the region, the center of which along the geomagnetic field line is projected to 200-230 km altitudes at a TC latitude. The third stage, which is typical of TC categories III-V, consists of the formation of an additional Ne peak (with a width reaching 1000 km) near the TC zenith. This peak includes Δ Ne disturbances and is accompanied by electrostatic oscillations at the H+ and He+ cyclotron frequencies and at the lower hybrid resonance frequency and by electric fields that are projected into the magnetically conjugate region. The crossing of New Caledonia by the category-IV TC Harry was considered in detail. It was shown that the neutral particle ascending jet probably deviated along the meridian in this case.

  9. Teleconnection between the South Atlantic convergence zone and the southern Indian Ocean: Implications for tropical cyclone activity

    Science.gov (United States)

    DeBlander, Evan; Shaman, Jeffrey

    2017-01-01

    A link between anomalous austral summer convection over the South Atlantic convergence zone (SACZ) and atmospheric conditions over the South Indian Ocean is investigated. Interannual north-south shifts in the SACZ produce a dipole of anomalous convection and precipitation over South America. The South Atlantic convergence zone index (SACZI) capturing this variability is presented and associated with a midlatitude Rossby wave train that propagates from South America eastward and south of Africa before curving north into the tropical Indian Ocean. This wave train is reproduced using Rossby wave ray tracing and simulations with a linearized barotropic vorticity equation model forced with divergence and convergence consistent with the observed dipole of anomalous convection. The wave train acts to excite anomalies in wind shear and relative humidity over the tropical south Indian Ocean, which in turn impact tropical cyclone (TC) genesis and distribution over this region. We find that changes in the wind shear and relative humidity associated with the SACZI effect changes in TC genesis, which result in a change in observed TC days over portions of the South Indian Ocean.

  10. Contribution of tropical cyclones to abnormal sea surface temperature warming in the Yellow Sea in December 2004

    Science.gov (United States)

    Kim, Taekyun; Choo, Sung-Ho; Moon, Jae-Hong; Chang, Pil-Hun

    2017-12-01

    Unusual sea surface temperature (SST) warming occurred over the Yellow Sea (YS) in December 2004. To identify the causes of the abnormal SST warming, we conducted an analysis on atmospheric circulation anomalies induced by tropical cyclones (TCs) and their impacts on upper ocean characteristics using multiple datasets. With the analysis of various datasets, we explored a new aspect of the relationship between TC activity and SST. The results show that there is a significant link between TC activity over the Northwest Pacific (NWP) and SST in the YS. The integrated effect of consecutive TCs activity induces a large-scale atmospheric cyclonic circulation anomaly over the NWP and consequently anomalous easterly winds over the YS and East China Sea. The mechanism of the unusually warm SST in the YS can be explained by considering TCs acting as an important source of Ekman heat transport that results in substantial intrusion of relatively warm surface water into the YS interior. Furthermore, TC-related circulation anomalies contribute to the retention of the resulting warm SST anomalies in the entire YS.

  11. Geomorphology and the World Wide Web

    Science.gov (United States)

    Shroder, John F.; Bishop, Michael P.; Olsenholler, Jeffrey; Craiger, J. Philip

    2002-10-01

    The Internet and the World Wide Web have brought many dimensions of new technology to education and research in geomorphology. As with other disciplines on the Web, Web-based geomorphology has become an eclectic mix of whatever material an individual deems worthy of presentation, and in many cases is without quality control. Nevertheless, new electronic media can facilitate education and research in geomorphology. For example, virtual field trips can be developed and accessed to reinforce concepts in class. Techniques for evaluating Internet references helps students to write traditional term papers, but professional presentations can also involve student papers that are published on the Web. Faculty can also address plagiarism issues by using search engines. Because of the lack of peer review of much of the content on the Web, care must be exercised in using it for reference searches. Today, however, refereed journals are going online and can be accessed through subscription or payment per article viewed. Library reference desks regularly use the Web for searches of refereed articles. Research on the Web ranges from communication between investigators, data acquisition, scientific visualization, or comprehensive searches of refereed sources, to interactive analyses of remote data sets. The Nanga Parbat and the Global Land Ice Measurements from Space (GLIMS) Projects are two examples of geomorphologic research that are achieving full potential through use of the Web. Teaching and research in geomorphology are undergoing a beneficial, but sometimes problematic, transition with the new technology. The learning curve is steep for some users but the view from the top is bright. Geomorphology can only prosper from the benefits offered by computer technologies.

  12. Significant Aerosol Influence on the Recent Decadal Decrease in Tropical Cyclone Activity Over the Western North Pacific

    Science.gov (United States)

    Takahashi, Chiharu; Watanabe, Masahiro; Mori, Masato

    2017-09-01

    Over the past two decades, the number of tropical cyclones (TCs) has decreased markedly in the southeastern part of the western North Pacific (WNP) as a component of the interdecadal variation. This decrease has partially been explained by an internal low-frequency variability of sea surface temperature (SST) in the Pacific, but influences of external forcing remain unclear. Here we show that past changes in sulfate aerosol emissions contributed approximately 60% of the observed decreasing trends in TC genesis frequency in the southeastern WNP for 1992-2011, using multiple simulations by a global climate model. This decrease was mainly attributed to the increased vertical wind shear and decreased low-level vorticity, associated with a trans-basin multidecadal SST change driven by aerosol forcing. The near-future projection shows that the aerosol forcing still has some potential influence on decadal TC change, but the projected decreasing frequency is mainly due to increasing greenhouse gases forcing.

  13. Influences of sea surface temperature in the tropical Pacific and Indian Oceans on tropical cyclone genesis over the western North Pacific in May

    Science.gov (United States)

    Huangfu, Jingliang; Chen, Wen; Ma, Tianjiao; Huang, Ronghui

    2017-11-01

    This study investigated the effects of sea surface temperature (SST) in different tropical regions on tropical cyclone (TC) genesis over the western North Pacific (WNP) in May. The results revealed that positive SST anomalies over the tropical Pacific (Indian) Ocean in March may lead to increased (decreased) numbers of TCs over the WNP in May by affecting the atmospheric circulation anomalies over the WNP. Warmer SSTs over the tropical Pacific Ocean (TPO) may lead to stronger low-level southwesterly winds and enhanced convection. However, warmer SSTs over the tropical Indian Ocean (TIO) may enhance the western part of the western Pacific subtropical high (WPSH) and suppress convection. Further analysis suggests that changes in the atmospheric circulation anomalies over the WNP are related to changes in environmental factors. Concomitantly with the positive SST anomalies over the TPO, a favorable environment for TC genesis in May is present, with stronger low-level relative vorticity and upper-level divergence, smaller vertical wind shear and abundant water vapor. In contrast, the positive SST anomalies over the TIO might lead to an unfavorable environment for TC genesis over the WNP. This study also investigated the joint contributions of the TPO and TIO, and the results indicate that positive SST anomalies over the TPO and negative SST anomalies over the TIO may lead to an increased number of TC geneses. The analysis of the energy budget suggests that the joint activity of the TPO and TIO influences the barotropic eddy kinetic energy conversions and is mainly attributed to the contributions from the meridional shear of the mean zonal winds and the zonal wind convergence.

  14. Precipitation response to solar geoengineering in a high-resolution tropical-cyclone permitting coupled general circulation model

    Science.gov (United States)

    Irvine, P. J.; Keith, D.; Dykema, J. A.; Vecchi, G. A.; Horowitz, L. W.

    2016-12-01

    Solar geoengineering may limit or even halt the rise in global-average surface temperatures. Evidence from the geoMIP model intercomparison project shows that idealized geoengineering can greatly reduce temperature changes on a region-by-region basis. If solar geoengineering is used to hold radiative forcing or surface temperatures constant in the face of rising CO2, then the global evaporation and precipitation rates will be reduced below pre-industrial. The spartial and frequency distribution of the precipitation response is, however, much less well understood. There is limited evidence that solar geoengineering may reduce extreme precipitation events more that it reduces mean precipitation, but that evidence is based on relatively course resolution models that may to a poor job representing the distribution of extreme precipitation in the current climate. The response of global and regional climate, as well as tropical cyclone (TC) activity, to increasing solar geoengineering is explored through experiments with climate models spanning a broad range of atmospheric resolutions. Solar geoengineering is represented by an idealized adjustment of the solar constant that roughly halves the rate of increase in radiative forcing in a scenario with increasing CO2 concentration. The coarsest resolution model has approximately a 2-degree global resolution, representative of the typical resolution of past GCMs used to explore global response to CO2 increase, and its response is compared to that of two tropical cyclone permitting GCMs of approximately 0.5 and 0.25 degree resolution (FLOR and HiFLOR). The models have exactly the same ocean and sea-ice components, as well as the same parameterizations and parameter settings. These high-resolution models are used for real-time seasonal prediction, providing a unified framework for seasonal-to-multidecadal climate modeling. We assess the extreme precipitation response, comparing the frequency distribution of extreme events with

  15. The influence of landfall variation on tropical cyclone losses in the United States as simulated by HAZUS

    Science.gov (United States)

    Sharp, Kevin Joseph

    Tropical cyclone losses in the United States have shown an increasing trend since the beginning of the 20th century. This is mainly due to increased exposure along America's coast. The amount of coastal property at risk persistently increases due to inflation, wealth increase, and population growth. When researchers have normalized the loss record to remove the influence of exposure and vulnerability change, no trend can be discerned in the damage record. This has been used to refute the claim that tropical cyclones are becoming more potentially destructive, and to keep the locus of explanation firmly in socio-demographic trends. But physical variation, in storm size, intensity and location, still make a significant difference in the impact of any individual storm event. This fact occasionally induces calls for renewed efforts at hurricane modification and routinely evokes a sense of either relief or alarm at "close calls" that, except for a difference of a few miles in landfall location or a modest weakening of peak winds, separate hurricane disasters from catastrophes. This project examined the effect of landfall location on storm damage using the Federal Emergency Management Agency's (FEMA) risk assessment model, HAZUS. Thirty-mile track shifts were prescribed for the top 10 most damaging storms in the normalized record since 1988. The alternate storms yielded drastically different damage estimates from the original storms, indicating large spatial variations in exposure. Each landfall shift resulted in a rank change in the overall normalized record. The damage record is dominated by individual extreme events like those used in this analysis, and although random, differences in landfall location would presumably average out in a long record. The fact that a few storms account for a large majority of losses, and that small differences in their landfall yield large differences in impact, points to a very large noise to signal ratio that would make it difficult to

  16. WRF simulation of the heavy rainfall over Metropolitan Manila, Philippines during tropical cyclone Ketsana: a sensitivity study

    Science.gov (United States)

    Cruz, F. T.; Narisma, G. T.

    2016-08-01

    In September 2009, tropical cyclone Ketsana brought record rainfall over Metropolitan Manila, Philippines, resulting in widespread flooding and incapacitated the city for days. The extensive damage caused by heavy rainfall events such as this highlights the need to have an effective weather prediction model to forecast these extreme events for the Philippines. As an initial step towards this goal, this study aims to examine the sensitivity of the rainfall simulation of the Weather Research and Forecasting (WRF) model to the physical parameterization schemes related to the planetary boundary layer (PBL) and microphysics processes. Comparison with observation data shows that the PBL scheme influences the spatial distribution of rainfall, whereas the microphysics scheme can affect rainfall magnitudes. The PBL scheme can also affect the intensity and track of the tropical cyclone as indicated in the surface latent heat flux and vertical velocity, as well as the magnitude of the mixing ratio of the different hydrometeors, which consequently affects the simulated rainfall. On the other hand, microphysics schemes can also influence the vertical distribution of each hydrometeor, likely due to differences in the treatment of ice phase processes and its interaction with the PBL scheme. Among the schemes tested, the model simulation using the ACM2 PBL and the WSM6 microphysics schemes captures this particular heavy rainfall event, in terms of spatial distribution, amount and timing. The results of this study show the importance of the PBL and microphysics schemes in simulating heavy rainfall, as well as the high potential of using WRF for future forecasts, especially for extreme weather events in the Philippines.

  17. Development and Application of an Objective Tracking Algorithm for Tropical Cyclones over the North-West Pacific purely based on Wind Speeds

    Science.gov (United States)

    Befort, Daniel J.; Kruschke, Tim; Leckebusch, Gregor C.

    2017-04-01

    Tropical Cyclones over East Asia have huge socio-economic impacts due to their strong wind fields and large rainfall amounts. Especially, the most severe events are associated with huge economic losses, e.g. Typhoon Herb in 1996 is related to overall losses exceeding 5 billion US (Munich Re, 2016). In this study, an objective tracking algorithm is applied to JRA55 reanalysis data from 1979 to 2014 over the Western North Pacific. For this purpose, a purely wind based algorithm, formerly used to identify extra-tropical wind storms, has been further developed. The algorithm is based on the exceedance of the local 98th percentile to define strong wind fields in gridded climate data. To be detected as a tropical cyclone candidate, the following criteria must be fulfilled: 1) the wind storm must exist for at least eight 6-hourly time steps and 2) the wind field must exceed a minimum size of 130.000km2 for each time step. The usage of wind information is motivated to focus on damage related events, however, a pre-selection based on the affected region is necessary to remove events of extra-tropical nature. Using IBTrACS Best Tracks for validation, it is found that about 62% of all detected tropical cyclone events in JRA55 reanalysis can be matched to an observed best track. As expected the relative amount of matched tracks increases with the wind intensity of the event, with a hit rate of about 98% for Violent Typhoons, above 90% for Very Strong Typhoons and about 75% for Typhoons. Overall these results are encouraging as the parameters used to detect tropical cyclones in JRA55, e.g. minimum area, are also suitable to detect TCs in most CMIP5 simulations and will thus allow estimates of potential future changes.

  18. Response of west Indian coastal regions and Kavaratti lagoon to the November-2009 tropical cyclone Phyan

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desai, R.G.P.; Mehra, P.; SanilKumar, V.; Radhakrishnan, K.V.; VijayKumar, K.; AshokKumar, K.; Agarwadekar, Y.; Bhat, U.G.; Luis, R.; Rivankar, P.; Viegas, B.

    ) because of lack of river influx and absence of a sufficiently large land boundary required for the generation and sustenance of wave/wind-driven water mass piling up at the land-sea interface. Keywords: Cyclonic storm `Phyan’, Internet-accessible... in the Lakshadweep Archipelago in the south-eastern Arabian Sea were made with the use of an Internet-accessible real/near-real time reporting Integrated Coastal Observation Network (ICON) designed, developed and established by the National Institute...

  19. Developing Basic Space Science World-Wide

    Science.gov (United States)

    Wamsteker, W.; Albrecht, Rudolf; Haubold, Hans J.

    2004-03-01

    When the first United Nations/European Space Agency Workshop for Basic Space Science was planned to be held in Bangalore, India (1991) on the invitation of ISRO, few of those involved could expect that a unique forum was going to be created for scientific dialogue between scientists from developing and industrialized nations. As the format of the first workshop was on purpose left free with time for presentations, working sessions, and plenary discussions, the workshop was left to find its own dynamics. After a decade of UN/ESA Workshops, this book brings together the historical activities, the plans which have been developed over the past decade in the different nations, and the results which have materialized during this time in different developing nations. It aims to achieve for development agencies to be assisted in ways to find more effective tools for the application of development aid. The last section of the book contains a guide for teachers to introduce astrophysics into university physics courses. This will be of use to teachers in many nations. Everything described in this book is the result of a truly collective effort from all involved in all UN/ESA workshops. The mutual support from the participants has helped significantly to implement some of the accomplishments described in the book. Rather than organizing this book in a subject driven way, it is essentially organized according to the common economic regions of the world, as defined by the United Nations (Africa, Asia and the Pacific, Europe, Latin America and the Caribbean, Western Asia). This allows better recognition of the importance of a regional (and at times) global approach to basic space science for the developing nation's world wide. It highlights very specific scientific investigations which have been completed successfully in the various developing nations. The book supplements the published ten volumes of workshop proceedings containing scientific papers presented in the workshops

  20. The mechanical influence of continental topography on the trajectories of tropical cyclones near the west coast of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Zavala Sanson, L. [Departamento de Oceanografia Fisica, CICESE, Ensenada, Baja California (Mexico)

    2004-07-01

    The evolution of tropical cyclonic vortices on the eastern North Pacific is examined by means of a barotropic model with an idealized continental topography. The aim of the study is to investigate the trajectories of cyclones in this area affected by both the topography and the planetary {beta} effects. The topographic {beta} effect is mainly due to the ascending slope of the orography, and induces the vortex to drift towards local northwest direction, which coincides with the geographical northwest (because of the topography orientation). As a result, the vortex drift is clearly enhanced when both effects are considered. The precise direction of the trajectory depends on the initial geographical position with respect to the continent. Vortices initialized at southeastern areas (around 12{center_dot} N, 95{center_dot} W) are deflected by the Sierra Madre del Sur more to the west, following a trajectory almost parallel to the continent. For vortices initialized at 15{center_dot} N or more, their drift is mainly due to the planetary {beta} effect, although eventually they are attracted towards the Sierra Madre Occidental at higher latitudes. These conclusion suggest the possible influence of orography on the trajectories of real tropical cyclones in this area. [Spanish] La evolucion de ciclones tropicales en el Pacifico Norte oriental es estudiada por medio de un modelo barotropico con topografia continental. El objetivo es investigar la trayectoria de vortices ciclonicos en esta area cuando son afectados solamente por los efectos {beta} planetario y topografico. Este ultimo se deba a la pendiente de la orografia continental e induce la deriva del vortice en la direccion noroeste local, la cual coincide con el noroeste geografico (debido a la orientacion de la topografia). Un claro resultado de la combinacion de estos dos mecanismos es el aumento de la rapidez de derivada del ciclon. La direccion precisa de la trayectoria depende de la posicion inicial con respecto

  1. Objective Tracking of Tropical Cyclones in the North-West Pacific Basin Based on Wind Field Information only

    Science.gov (United States)

    Leckebusch, G. C.; Befort, D. J.; Kruschke, T.

    2016-12-01

    Although only ca. 12% of the global insured losses of natural disasters occurred in Asia, there are two major reasons to be concerned about risks in Asia: a) The fraction of loss events was substantial higher with 39% of which 94% were due to atmospheric processes; b) Asia and especially China, is undergoing quick transitions and especially the insurance market is rapidly growing. In order to allow for the estimation of potential future (loss) impacts in East-Asia, in this study we further developed and applied a feature tracking system based on extreme wind speed occurrences to tropical cyclones, which was originally developed for extra-tropical cyclones (Leckebusch et al., 2008). In principle, wind fields will be identified and tracked once a coherent exceedance of local percentile thresholds is identified. The focus on severe wind impact will allow an objective link between the strength of a cyclone and its potential damages over land. The wind tracking is developed in such a way to be applicable also to course-gridded AOGCM simulation. In the presented configuration the wind tracking algorithm is applied to the Japanese reanalysis (JRA55) and TC Identification is based on 850hPa wind speeds (6h resolution) from 1979 to 2014 over the Western North Pacific region. For validation the IBTrACS Best Track archive version v03r8 is used. Out of all 904 observed tracks, about 62% can be matched to at least one windstorm event identified in JRA55. It is found that the relative amount of matched best tracks increases with the maximum intensity. Thus, a positive matching (hit rate) of above 98% for Violent Typhoons (VTY), above 90% for Very Strong Typhoons (VSTY), about 75% for Typhoons (TY), and still some 50% for less intense TCs (TD, TS, STS) is found. This result is extremely encouraging to apply this technique to AOGCM outputs and to derive information about affected regions and intensity-frequency distributions potentially changed under future climate conditions.

  2. Interdecadal variation of tropical cyclone genesis and its relationship to the convective activities over the central Pacific

    Science.gov (United States)

    Huangfu, Jingliang; Huang, Ronghui; Chen, Wen

    2017-04-01

    Using the outgoing longwave radiation (OLR) data from the National Oceanic and Atmospheric Administration archives, this paper analyzes the interdecadal variation of convective activities over the central Pacific (CP) from July to October of 1979-2013 and its impact on tropical cyclone (TC) genesis in the western North Pacific (WNP). Concurrent with the interdecadal decrease of TC genesis, the tropical convection underwent a significant interdecadal change in the late 1990s. Overall, the first leading empirical orthogonal function mode of the tropical OLR during July-October turned from a zonal dipole pattern during 1979-1997 to a tripole pattern during 1998-2013. Concomitant to this change, the boreal part of the Walker circulation shrank westward, with its downdraft branch located over the CP. The downward motion anomalies over the CP increased after the late 1990s, as did the trade easterlies. Consistent with the CP convective activity anomalies, the negative low-level relative vorticity anomalies and upper-level divergence anomalies, positive vertical wind shear anomalies and anomalous abundant water vapor can be observed over the southeastern part of the WNP. Additionally, the tropical depression (TD)-type waves associated with the CP convective activities are significantly different before and after the late 1990s. Before the late 1990s, the off-equatorial TD-type waves could be distinctly observed, with clear transitions located along the WNP monsoon trough. However, these transitions were vague after the late 1990s. Therefore, the convective activities over the CP may have played an important role in affecting the interdecadal change of TC genesis by affecting the genesis of TD-type waves.

  3. Mitigation of Natural Hazards and Disasters. International Perspectives. Mitigation of the Impact of Tropical Cyclones in Northern Australia through Community Capacity Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Anderson-Berry, L. [Disaster Mitigation Policy Planning Services, Australian Bureau of Meteorology, Melbourne, Victoria (Australia); King, D. [Centre for Disaster Studies, James Cook University, Carins, Queensland, 4870 (Australia)

    2005-07-15

    Community mitigation of hazard impact requires hazard knowledge and preparedness on the part of the members of diverse and complex communities. Longitudinal research in the tropical cyclone prone north of Australia has gathered extensive datasets on community awareness, preparedness and knowledge, in order to contribute to education campaigns and mitigation strategies. Data have been used to identify issues of vulnerability to cyclones and capacity to deal with the hazard. This has been developed as a community vulnerability and capacity model that may be applied to diverse communities in order to assess levels of capability to mitigate and deal with the cyclone hazard. The model is presented here in a simplified form as its development is evolving and ongoing.

  4. Seasonal Environmental Characteristics for the Tropical Cyclone Genesis in the Indian Ocean during the CINDY2011/DYNAMO Field Experiment

    Directory of Open Access Journals (Sweden)

    Aya Tsuboi

    2016-05-01

    Full Text Available This study investigated the seasonal environmental characteristics for tropical cyclone genesis (TCG over the Indian Ocean during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 and the Dynamics of the Madden–Julian Oscillation (MJO (CINDY2011/DYNAMO field experiment and compare them with long-term climatological features. It was found that the spatial pattern of an empirical environmental index for TCG over the tropical Indian Ocean in 2011 is very similar to the feature composited over the years with high activity of MJO. The analyses of the contributions from each environmental factor indicated that relative humidity, absolute vorticity, and vertical velocity contribute to generate positive influences on the conditions for TCG in 2011. The influences of La Niña appear only through a shear effect over the Indian Ocean in 2011. Under the influences of active MJO events during the CINDY2011/DYNAMO period, the environmental conditions for TCG over the Indian Ocean are determined more strongly by MJO than by La Niña, through modifications of some environmental properties favorable for TCG. The environmental characteristics during CINDY2011/DYNAMO seem to be quite typical of the MJO active years; in such a case, the influences of El Niño/La Niña would not appear in determining the environmental conditions for TCG over the Indian Ocean.

  5. Multiday evolution of convective bursts during western North Pacific tropical cyclone development and nondevelopment using geostationary satellite measurements

    Science.gov (United States)

    Chang, Minhee; Ho, Chang-Hoi; Park, Myung-Sook; Kim, Jinwon; Ahn, Myoung-Hwan

    2017-02-01

    Tropical cyclones (TCs) develop through latent heating from a series of deep convection. To investigate the evolution of diurnal convective burst (CB) activities prior to TC formation, we analyzed 463 tropical disturbances that developed (80) or not developed (383) into TCs over the western North Pacific during the 2007-2009 period. Geostationary satellite data allowed defining deep convection where infrared (IR) brightness temperature is lower than that of water vapor (WV). Diurnal expansions from time series of IR minus WV mCB) are observed in 67.5% of the 80 TC formation cases and in 13.8% of the 383 nonformation cases. Intensities of the middle-to-low tropospheric relative vorticity of these two groups are comparable on 4 to 5 days prior to TC formation. However, vorticity intensification is weak for nondeveloping disturbances in environments of strong vertical wind shear; these disturbances eventually decay. The vorticity of developing disturbances continuously intensifies to TC strengths. The remaining 32.5% of the TC cases without mCB show weaker initial vorticity, but rapid intensification over 3 day periods before TC formation. The present results reveal that mCB is a common feature in pre-TC stages, and large-scale environments of weak vertical wind shear are critical for the formation of TC-strength circulations.

  6. Tropical Cyclone Report: Joint Typhoon Warning Center Guam, Mariana Islands, 1991

    Science.gov (United States)

    1991-01-01

    Typhoon Pat (24W) at 070511Z October 1991 is transformed by the Meteorological Imagery, Data Display, and Analysis System (MIDDAS) software into a three...cyclone. Figure 3-30-4. Yuri’s high winds uprooted this large tree and parked it on a car. The more flexible, smaller coconut palms in the background...NO. LAT L= K / DQ0 2A 48 M2 2 48 Z 2 -4 2 M 00 2A 4l UI 91092106 22 14.5N 137.2E 95 8 45 110 260 -45 -47 147 -6 100 216 5 -25 -25 -25 91092112 23 14.7N

  7. Towards Direct Simulation of Future Tropical Cyclone Statistics in a High-Resolution Global Atmospheric Model

    Directory of Open Access Journals (Sweden)

    Michael F. Wehner

    2010-01-01

    Full Text Available We present a set of high-resolution global atmospheric general circulation model (AGCM simulations focusing on the model's ability to represent tropical storms and their statistics. We find that the model produces storms of hurricane strength with realistic dynamical features. We also find that tropical storm statistics are reasonable, both globally and in the north Atlantic, when compared to recent observations. The sensitivity of simulated tropical storm statistics to increases in sea surface temperature (SST is also investigated, revealing that a credible late 21st century SST increase produced increases in simulated tropical storm numbers and intensities in all ocean basins. While this paper supports previous high-resolution model and theoretical findings that the frequency of very intense storms will increase in a warmer climate, it differs notably from previous medium and high-resolution model studies that show a global reduction in total tropical storm frequency. However, we are quick to point out that this particular model finding remains speculative due to a lack of radiative forcing changes in our time-slice experiments as well as a focus on the Northern hemisphere tropical storm seasons.

  8. Analysis of a Non-Developing Tropical Circulation System During the Tropical Cyclone Structure (TCS08) Field Experiment

    Science.gov (United States)

    2009-12-01

    Atmospheric Research (NCAR) and the Centre de Recherché en Physique de L’Environment Terrestre et Planetaire (CRPE), France. The first deployment of...were made available for TCS08 via the Year of Tropical Convection (YOTC) archive. For this study, wind, geopotential, and vorticity fields are used

  9. Genesis of Twin Tropical Cyclones as Revealed by a Global Mesoscale Model: The Role of Mixed Rossby Gravity Waves

    Science.gov (United States)

    Shen, Bo-Wen; Tao, Wei-Kuo; Lin, Yuh-Lang; Laing, Arlene

    2012-01-01

    In this study, it is proposed that twin tropical cyclones (TCs), Kesiny and 01A, in May 2002 formed in association with the scale interactions of three gyres that appeared as a convectively coupled mixed Rossby gravity (ccMRG) wave during an active phase of the Madden-Julian Oscillation (MJO). This is shown by analyzing observational data, including NCEP reanalysis data and METEOSAT 7 IR satellite imagery, and performing numerical simulations using a global mesoscale model. A 10-day control run is initialized at 0000 UTC 1 May 2002 with grid-scale condensation but no sub-grid cumulus parameterizations. The ccMRG wave was identified as encompassing two developing and one non-developing gyres, the first two of which intensified and evolved into the twin TCs. The control run is able to reproduce the evolution of the ccMRG wave and thus the formation of the twin TCs about two and five days in advance as well as their subsequent intensity evolution and movement within an 8-10 day period. Five additional 10-day sensitivity experiments with different model configurations are conducted to help understand the interaction of the three gyres, leading to the formation of the TCs. These experiments suggest the improved lead time in the control run may be attributed to the realistic simulation of the ccMRG wave with the following processes: (1) wave deepening (intensification) associated with a reduction in wavelength and/or the intensification of individual gyres, (2) poleward movement of gyres that may be associated with boundary layer processes, (3) realistic simulation of moist processes at regional scales in association with each of the gyres, and (4) the vertical phasing of low- and mid-level cyclonic circulations associated with a specific gyre.

  10. Climatological analysis of passage-type tropical cyclones from the Western North Pacific into the South China Sea

    Directory of Open Access Journals (Sweden)

    Jau-Ming Chen

    2017-01-01

    Full Text Available Tropical cyclone (TC climatological characteristics with passage from the Western North Pacific (WNP into the South China Sea (SCS during the June - November season are analyzed in this study. These TCs tend to form in the WNP west of 150°E, and on average westward by 7 - 12° in longitude than TCs that do not track into the SCS. Their formation locations migrate with the monsoon trough, moving northward from June to August, and southward from September to November. The probability of a WNP TC moving into the SCS varies seasonally, with only 12 - 18% of the WNP TCs doing so during August-September due to more northern TC formation. However, this probability rises to 25 - 26% in June - July and 25 - 32% in October - November with more southern TC formation. The passage-type TCs generally form in the eastern part of an elongated lower-level cyclonic anomaly of the 10-day low-pass filtered environmental circulation in the 10 - 20°N zone, which is paired with an anticyclonic anomaly to the north. Between this circulation pair, anomalous easterly flows steer these TCs westward, giving them a westward track into the SCS. The formation of these passage-type TCs is associated with a southward displacement of the monsoon trough and a westward intensification of the Pacific subtropical high in August and September. During June - July (October - November, the associated features appear as a southeastward (meridional expansion of the monsoon trough and a northward displacement of the Pacific subtropical high.

  11. Potential impacts of assimilating all-sky infrared satellite radiances from GOES-R on convection-permitting analysis and prediction of tropical cyclones

    Science.gov (United States)

    Zhang, Fuqing; Minamide, Masashi; Clothiaux, Eugene E.

    2016-03-01

    The potential impacts of GOES-R satellite radiances on tropical cyclone analysis and prediction were examined through ensemble correlations between simulated infrared brightness temperatures and various model state variables. The impacts of assimilating GOES-R all-sky infrared brightness temperatures on tropical cyclone analysis and prediction were further demonstrated through a series of convection-permitting observing system simulation experiments using an ensemble Kalman filter under both perfect and imperfect model scenarios. Assimilation of the high temporal and spatial resolution infrared radiances not only constrained well the thermodynamic variables, including temperature, moisture, and hydrometeors, but also considerably reduced analysis and forecast errors in the wind fields. The potential of all-sky radiances is further demonstrated through an additional proof-of-concept experiment assimilating real-data infrared brightness temperatures from GOES 13 satellite which was operational in an enhanced scanning mode during Hurricane Karl (2010).

  12. An Observing System Simulation Experiment (OSSE to Assess the Impact of Doppler Wind Lidar (DWL Measurements on the Numerical Simulation of a Tropical Cyclone

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2010-01-01

    Full Text Available The importance of wind observations has been recognized for many years. However, wind observations—especially three-dimensional global wind measurements—are very limited. A satellite-based Doppler Wind Lidar (DWL is proposed to measure three-dimensional wind profiles using remote sensing techniques. Assimilating these observations into a mesoscale model is expected to improve the performance of the numerical weather prediction (NWP models. In order to examine the potential impact of the DWL three-dimensional wind profile observations on the numerical simulation and prediction of tropical cyclones, a set of observing simulation system experiments (OSSEs is performed using the advanced research version of the Weather Research and Forecasting (WRF model and its three-dimensional variational (3DVAR data assimilation system. Results indicate that assimilating the DWL wind observations into the mesoscale numerical model has significant potential for improving tropical cyclone track and intensity forecasts.

  13. Extreme multi-basin flooding linked with extra-tropical cyclones

    Science.gov (United States)

    De Luca, Paolo; Hillier, John K.; Wilby, Robert L.; Quinn, Nevil W.; Harrigan, Shaun

    2017-11-01

    Fluvial floods are typically investigated as ‘events’ at the single basin-scale, hence flood management authorities may underestimate the threat of flooding across multiple basins driven by large-scale and nearly concurrent atmospheric event(s). We pilot a national-scale statistical analysis of the spatio-temporal characteristics of extreme multi-basin flooding (MBF) episodes, using peak river flow data for 260 basins in Great Britain (1975‑2014), a sentinel region for storms impacting northwest and central Europe. During the most widespread MBF episode, 108 basins (~46% of the study area) recorded annual maximum (AMAX) discharge within a 16 day window. Such episodes are associated with persistent cyclonic and westerly atmospheric circulations, atmospheric rivers, and precipitation falling onto previously saturated ground, leading to hydrological response times distributed, yet differentially time-lagged, wind and flood damages. These findings have implications for emergency responders, insurers and contingency planners worldwide.

  14. A New Tropical Cyclone Dynamic Initialization Technique Using High Temporal and Spatial Density Atmospheric Motion Vectors and Airborne Field Campaign Data

    Science.gov (United States)

    Hendricks, Eric A.; Bell, Michael M.; Elsberry, Russell L.; Velden, Chris S.; Cecil, Dan

    2016-01-01

    Background: Initialization of tropical cyclones in numerical weather prediction (NWP) systems is a great challenge: Mass-wind ?eld balance; Secondary circulation and heating; Asymmetries. There can be large adjustments in structure and intensity in the ?rst 24 hours if the initial vortex is not in balance: Spurious gravity waves; Spin-up (model and physics). Existing mesoscale NWP model TC (Tropical Cyclone) initialization strategies: Bogus vortex, cold start from global analyses; 3DVAR or 4DVAR, possibly with synthetic observations; EnKF (Ensemble Kalman Filter); Dynamic initialization. Dynamic initialization allows vortex to have improved balance and physics spin-up at the initial time (e.g., Hendricks et al. 2013, 2011; Nguyen and Chen 2011; Fiorino and Warner 1981; Hoke and Anthes 1976). Himawari-8 geostationary satellite has capability of continuous imagery (10-minutes) over the full disk: New GOES-R satellites will have same capability. This will allow for unprecedented observations of tropical cyclones. However, current data assimila1on systems are not capable of ingesting such high temporal observations (Atmospheric Mo1on Vectors - AMVs). Hourly AMVs are produced, and thinned to 100-kilometer spacing in the horizontal. An entirely new data assimilation concept is required to utilize these observations.

  15. Characterization of rainfall distribution and flooding associated with U.S. landfalling tropical cyclones: Analyses of Hurricanes Frances, Ivan, and Jeanne (2004)

    Science.gov (United States)

    Villarini, Gabriele; Smith, James A.; Baeck, Mary Lynn; Marchok, Timothy; Vecchi, Gabriel A.

    2011-12-01

    Rainfall and flooding associated with landfalling tropical cyclones are examined through empirical analyses of three hurricanes (Frances, Ivan, and Jeanne) that affected large portions of the eastern U.S. during September 2004. Three rainfall products are considered for the analyses: NLDAS, Stage IV, and TMPA. Each of these products has strengths and weaknesses related to their spatio-temporal resolution and accuracy in estimating rainfall. Based on our analyses, we recommend using the Stage IV product when studying rainfall distribution in landfalling tropical cyclones due to its fine spatial and temporal resolutions (about 4-km and hourly) and accuracy, and the capability of estimating rainfall up to 150 km from the coast. Lagrangian analyses of rainfall distribution relative to the track of the storm are developed to represent evolution of the temporal