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Tropical Cyclone Forecaster Reference Guide
7. TROPICAL CYCLONE STRUCTURE
Editor: Jan-Hwa Chu, NRL
Contributors: Jan-Hwa Chu, NRL, Charles P. Guard, Univeristy of Guam, Charles J. Neumann, SAIC, and Charles R. Sampson, NRL
Naval Research Laboratory (NRL)
Marine Meteorology Division
7 Grace Hopper Drive, Stop 2
Monterey, CA 93943-5006
Initially prepared as a NRL internal report, October 1995. HTML conversion date: 9 February 1999
ABSTRACT
History has shown that a key to successful military operations is to take full advantage of the climate and weather information (Jacobs, 1947; Harding and Kotsch, 1965; Moorer, 1966; Adamson and Kosco, 1967; Halacy, 1968; Kotsch and Henderson, 1984; Bates and Fuller, 1986; AMS, 1990). This is especially true in regions where tropical cyclones and associated winds, torrential rains, coastal storm surges, high seas, and long period swells exist (Calhoun, 1981). The tropical cyclone is the greatest natural enemy for military operations ashore and afloat. The purpose of Tropical Cyclone Forecaster Reference Guide is to provide a ready, non-mathematical, operational reference for forecasters who provide meteorology support to staff commanders. This report provides an overview of the tropical cyclone structure. Subjects discussed include size, temperature, moisture, wind, and rainband structures of tropical cyclones. The topographic effects on cyclone circulation, reclassification from tropical into extra-tropical cyclone and computer simulation of mature tropical cyclones are also discussed. A Miscellaneous Section is included for special topics, such as tornadoes associated with a tropical cyclone. Tropical cyclone intensity is discussed in Chapter 6 of this Reference Guide.
KEY WORDS:
Tropical cyclone structure. Tropical cyclone size, thermal structure, horizontal and vertical wind structures, center and eye, tropical cyclone cloudiness, rainbands, liquid water content and rainfall. Topographic and terrain effects on tropical cyclone structure. Cyclone reclassification from a tropical to extra-tropical cyclone. Tornadoes associated with tropical cyclone. Numerical and computer simulations of tropical cyclone.
CHAPTER 7 TABLE OF CONTENTS
1. INTRODUCTION
2. SIZE OF A TROPICAL CYCLONE
3. THERMAL STRUCTURE OF A TROPICAL CYCLONE
3.1 Pressure near the sea surface
3.2 Air temperature and moisture near the sea surface
3.3 Temperature and moisture aloft
3.4 Vertical thermal stratification
4. WIND STRUCTURE OF A TROPICAL CYCLONE
4.1 Winds in the lower troposphere
4.2 Winds in the middle and upper troposphere
4.3 Distribution of angular momentum and vorticity
4.4 Vertical motion field
5. THE CENTER AND THE EYE OF A TROPICAL CYCLONE
5.1 Methods for locating the cyclone center
5.2 Size and shape of the cyclone eye
5.3 Temperature, moisture and circulation in the eye
6. CLOUDINESS, RAINBANDS, LIQUID-WATER CONTENT AND RAINFALL
6.1 Cloudiness and rainbands
6.2 Liquid-water content
6.3 Rainfall
7. TOPOGRAPHIC EFFECTS
7.1 Flat land
7.2 Island with high mountain range
8. CYCLONE RECLASSIFICATION FROM TROPICAL TO EXTRA-TROPICAL
9. MISCELLANEOUS
9.1 Tornadoes associated with tropical cyclones and forecast guidance
10. COMPUTER SIMULATIONS
10.1 Practical needs and scientific basis
10.2 Error sources associated with computer simulations
10.3 The feasibility of tropical cyclone simulations
10.4 Conclusions from tropical cyclone simulations
11. SUMMARY AND OUTLOOK
Appendix A: A comparison of the characteristics of a mean
tropical cyclone with a mean extra-tropical cyclone
Appendix B: A comparison of the characteristics of a mean
hurricane tornado with a mean non-hurricane tornado
REFERENCES
List of Figures
List of Tables
ACKNOWLEDGMENTS
By its very nature this technical note is completely dependent upon the contributions of other authors to meteorological literature. Tropical cyclone lecture notes, meticulously prepared by Professor M. Yanai at the University of California at Los Angeles, are found to be extremely informative while preparing this note. Special thanks to Mr. R. Bankert at the NRL, for improving the manuscripts. Special thanks also to Mr. E. M. Fukada at the Naval Western Oceanography Center, Pearl Harbor, Hawaii, for their comments on the manuscripts. Thanks to Mr. C. A. Moren at the MAR, Inc. for clarifying the applications of the dangerous wind radii and the wind strike probability. Thanks to LCDR R. L. Beard, Mr. Frank Wells, CAPT D. Mundall, and Capt. E. B. Borelli at JTWC for sharing their climatological information base. Thanks to Mr. S. Bishop at NRL for editorial and drafting efforts. Thanks also goes to the sponsor, Space and Naval Warfare Systems Command for their support of 6.3 type of funding in the fiscal year 1992 (PMW-165, Program Element 63704N).
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Chapter 7