85th AMS Annual Meeting

Sunday, 9 January 2005
Remote sensing and in situ observations of tropical cyclone structure at landfall
Kevin M. Grise, Pennsylvania State University, University Park, PA
A comprehensive analysis of tropical cyclone precipitation structures was conducted using data from the Tropical Rainfall Measuring Mission (TRMM), ground-based radar, rain gauges, and the National Lightning Detection Network . Each one of these products had particular advantages but also certain limitations due to its inherent physical properties and collection procedures. Combining all of the information from these individual data sets provided the clearest depiction of the precipitation structures of three Atlantic basin tropical cyclones: Hurricane Lili (2002), Tropical Storm Bill (2003), and Hurricane Ivan (2004). The precipitation patterns from these storms were analyzed to compare the individual data sets and to evaluate lightning as an effective indicator for tropical cyclone status. In this study, all data types were generally in agreement on the distribution of precipitation, although the infrared instruments sensed regions of the coldest cloud tops rather than regions of precipitation. For Hurricanes Lili and Ivan, these TRMM-combined infrared results were consistent with a cyclonic separation between associated cloud and precipitation regions, a characteristic that becomes more defined in dynamically stronger systems. In addition to the intercomparison of data types, the three tropical cyclones were evaluated in terms of lightning data. Most lightning occurred in the outer rainband regions of all three storms with substantially less occurring near the storm centers. In Hurricane Lili, a sharp intensification in these lightning patterns near the storm center signaled the sudden decay of the storm several hours later.

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