Quantifying Environmental Control on Tropical Cyclone Intensity Change

• Main Authors: Hendricks, Eric A., Peng, Melinda S., Fu, Bing, Li, Tim
• Other Authors: NAVAL RESEARCH LAB MONTEREY CA MARINE METEOROLOGY DIV
• Format: Text
• Language: English
• Published: 2010
• Subjects: Meteorology; *TROPICAL CYCLONES; DISTRIBUTION FUNCTIONS; TEMPERATURE; OCEAN SURFACE; INTENSITY CHANGES; COMPOSITE ANALYSIS; RAPIDLY INTENSIFYING; SEA SURFACE TEMPERATURE; PE0602435N; Pacific; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA532937; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA532937

Composite analysis is used to examine 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 intensity change bins are defined: rapidly intensifying (RI), intensifying neutral, and weakening. The Navy Operational Global Atmospheric Prediction System daily 0000 and 1200 UTC global analysis and Tropical Rainfall Measuring Mission Microwave Imager data are then used as proxies for the real atmosphere, and composites of various environmental fields believed relevant to TC intensity change are made in the vicinity of the TCs. These composites give the average characteristics near the TC, prior to undergoing a given intensity change episode. For the environmental variables, statistically significant differences are examined between RI storms and the other groups. While some environmental differences were found between RI and weakening/neutral TCs in both basins, an interesting result from this study is that the environment of RI TCs and intensifying TCs is quite similar. This indicates that the rate of intensification is only weakly dependent on the environmental conditions, on average, provided the environment is favorable. Notable exceptions were that in the WPAC RI events occurred in environments with significantly larger conditional instability than intensifying events. In the ATL, RI events occurred in environments with weaker deep-layer shear than intensifying events. An important finding of this work is that SSTs are similar between intensifying and rapidly intensifying TCs indicating that the rate of intensification is not critically dependent on SST. Published in Monthly Weather Review, v138 p3243-3271, Aug 2010. Sponsored in part by NRL N00173-06-1-07031.