Southern Hemisphere Application of the Systematic Approach to Tropical Cyclone Track Forecasting. Part 3, Updated Environmental Structure Characteristics (original) (raw)
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1998
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1998
Public reporting burden for this collection of information is estimated to average I hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection ofinformation, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office ofrManagement and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 14. SUBJECT TERMS 15. NUMBER Tropical cyclone track forecasting; Tropical cyclone motion OF PAGES 68 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. OF REPORT OF THIS PAGE OF ABSTRACT LIMITATION UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED OF ABSTRACT7 NSN 7540-01-280-5800 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std 239-18 School and the Australian Bureau of Meteorology. A second three-month visit by Tony Bannister of the Perth, Western Australia office was arranged. The Bureau of Meteorology funded the salary and this SPAWAR contract paid the travel and per diem to facilitate this exchange. Best-track tropical cyclone records were provided by the Joint Typhoon Warning Center, Guam, and NOGAPS analyses were provided by the Fleet Numerical Meteorology and Oceanography Center. Bob Creasey assisted in recovering NOGAPS analyses missing from the NPS archive for four tropical cyclones during 1994-1997. Mrs. Penny Jones expertly typed the manuscript.
This Meteorological knowledge base for application of the Systematic Approach to Tropical Cyclone Track Forecasting in the Atlantic basin follows from similar knowledge bases previously developed for the western North Pacific, the eastern and central North Pacific, and the Southern Hemisphere. A common environment structure terminology has been adopted in which three synoptic patterns (Standard, Poleward, and Midlatitude) are found in each of these basins. Each basin also has a special pattern, which in the Atlantic is the Upper-level low. The conceptual models for these synoptic patterns with their associated synoptic regions are described here via a conceptual model, analysis examples, and the characteristic track segments within each region. A climatology of occurrences in each patter/region for the 1568 cases during 1990-98 is prepared. The second key element in the knowledge base is the transitional mechanisms that change the environment structure and thus change the tropical c...
Meteorology and Atmospheric Physics, 1998
A critical meteorological knowledge base for the application of the Systematic Approach to Tropical Cyclone Track Forecasting of Cart and Elsberry is the environment structure, which is a small set of synoptic patterns and synoptic regions that characterize the tracks. As the original Systematic Approach for the western North Pacific has been applied to the eastern and central North Pacific by Boothe and to the Southern Hemisphere by Bannister et al., the conceptual models of the synoptic patterns have been generalized. Whereas only slight modifications of three of the original four synoptic patterns are required in the two new basin applications, the monsoon gyre pattern of the western North Pacific must be replaced with an upper-low pattern in the eastern and central North Pacific and by a high-amplitude midlatitude trough/ridge in the Southern Hemisphere. An important conclusion is that the environment structure of all tropical cyclones in these three basins could be classified into these small sets. Furthermore, each synoptic pattern/region has a set of characteristic tracks, and a change in environment structure has an associated track change. Comparisons and contrasts of these environmental structures demonstrates that the relative importance of the monsoon trough, subtropical ridge, and midlatitude circulations can account for first-order variations in TC tracks within these three tropical cyclone basins. Summaries of the occurrence of synoptic pattern/region transitions are given" for the three basins. Although each TC basin has special characteristics, the general application of the Systematic Approach suggests a unified treatment is possible. Further development along this line is expected to improve the accuracy and consistency of forecasts and warnings.
Annual Tropical Cyclone Report 2010
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1st WMO INTERNATIONAL CONFERENCE ON TROPICAL CYCLONES AND CLIMATE CHANGE
A study is undertaken to find out characteristics of interannual variation like coefficient of variation, trends and periodicities etc. in the annual frequencies of different categories of disturbances such as depressions, cyclonic storms, severe cyclonic storms, total cyclonic storms and total cyclonic disturbances landfalling over different coastal states of India and other member countries of World Meteorological Organisation (WMO) / Economic and Social Cooperation for Asia and the Pacific (ESCAP) Panel based on the data of 115 years . Considering different coastal states of India, about 68% of the disturbances developing over the Bay of Bengal have landfall over east coast and about 30% of the disturbances developing over the Arabian Sea have landfall over west coast. Out of total disturbances having landfall over east and west coasts of India, about 85% and 44% cross Orissa and Gujarat coasts respectively. While the frequency of severe cyclonic storms crossing Andhra Pradesh coast shows significant increasing trend, the frequencies of cyclonic storms crossing Orissa, West Bengal and Gujarat coasts show significant decreasing trends. The sixth order polynomial trends could be well fitted to the frequencies of different categories of disturbances crossing the coasts during this period. The quasi-biennial oscillation (QBO) is significantly observed in the frequency of cyclonic storms crossing Orissa coast. The cyclonic storms crossing Andhra Pradesh and Tamil Nadu coasts show significant cycles of 5-6 years. The severe cyclonic storms crossing Andhra Pradesh coast exhibits QBO and that crossing West Bengal coast shows QBO as well as 4-5 years cycle of oscillation. There is no periodicity in the frequency of disturbances landfalling over other coastal states of India. The results and analysis for other member countries of WMO/ESCAP Panel, as per the above mentioned procedure, has been presented and discussed in detail in this study.
International Journal of Climatology, 2019
Evaluating cyclone tracks in climate models represents an excellent way to evaluate their ability to simulate synoptic-scale phenomena. Cyclone tracks were generated from two free-runs from the National Centers for Environmental Prediction Climate Forecast System (CFSv1) model for the Southern Hemisphere (SH), and compared with cyclone tracks generated from CFS reanalysis and ERA Interim data from 1979 to 2016. It is demonstrated that CFSv1 is capable of simulating realistic SH cyclone track climatology for both intensity and frequency. The CFSv1's ability to capture interannual variability is also highlighted. Specifically, the impacts of the Antarctic Oscillation (AAO), El Niño/Southern Oscillation (ENSO), and the Indian Ocean Dipole (IOD) on cyclone track frequency and intensity were assessed. The CFSv1 exhibits an annular structure in frequency and intensity in response to the AAO. For the reanalysis data, AAO cyclone frequency is less annular in the South Pacific especially during Austral Summer, possibly due to a positive trend in the AAO in recent decades. To test this, a reconstruction of cyclone tracks for ERA40 data from 1958 to 2001 produces a more annular structure. The response of cyclone tracks due to ENSO is fairly robust, with the reanalysis datasets and one member of the CFSv1 producing a pattern of cyclone variability consistent with the Pacific South American teleconnection pattern. In contrast, the cyclone frequency and intensity response to the IOD shows little agreement between reanalysis and CFSv1. An examination of 200-hPa stream function supports the CFS model producing a teleconnection response to ENSO but not the IOD, possibly due to anomalous heating generated from the IOD being too small. Our results suggest that assessing interannual variability of cyclone tracks in current state-of-the-art models be done with large-number ensembles when possible, especially when considering sensitivity to initial conditions and the magnitude of external forcing.