Recorded presentation4B.3
What are the characteristics of convective systems leading up to tropical cyclogenesis? A multisatellite investigation
Jonathan Zawislak, University of Utah, Salt Lake City, UT; and E. Zipser
The properties of convection involved in Atlantic tropical cyclogenesis events are investigated using a multisatellite platform approach. One of the outstanding issues in tropical cyclogenesis remains the interaction of deep convection with the larger scale environment. If there is a mid-level vorticity maximum, what processes lead to a concentration of vorticity at low-levels? For this study, the main question is: what are the characteristics of convective bursts/raining areas leading up to cyclogenesis? The investigation will be carried out through a few carefully-selected case studies between 2002-2008. The goal is to obtain multiple satellite overpasses of vorticity centers prior to cyclogenesis from a number of satellite platforms, including microwave sensors (AMSR-E, SSM/I, and TMI) and the TRMM Precipitation Radar (PR), against the background of geosynchronous infrared (IR) and visible data from GOES and METEOSAT. Vorticity maxima are back-tracked from the NHC best-track locations using multiple (re)analyses, most likely NCEP/NCAR reanalysis (6 hr/2.5°), ERA Interim analysis (6 hr/1.5°) and MERRA (3hr/1.25°). In addition to describing the convective systems observed, these analyses are compared to one another to note differences in vorticity maxima location, magnitude, and environmental conditions.
Of particular interest is the location and distance of raining areas from the vorticity center, the fractional area classified as convective, and metrics for the intensity of the convection. The nature of the convective organization (isolated deep convective cells, large stratiform rain areas, stratiform with embedded convective cells, squall-line) is also specified. Though its success is tied to the samples' range of times prior to cyclogenesis, a specific project goal is to understand the evolution of convection in the hours (~72) leading up to the cyclogenesis event. In particular (using IR), we evaluate the evolution of convective bursts and what differentiates the environments of events that have multiple bursts before genesis from those with a single convective burst.
Session 4B, Tropical Cyclone Formation: Physical Processes
Monday, 10 May 2010, 3:30 PM-5:15 PM, Arizona Ballroom 2-5
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