Seventh Annual AMS Student Conference


Analysis of deep convective cell motions within an intense hurricane

Brett G. Odom, University of North Carolina, Charlotte, NC; and M. D. Eastin

Convective cells within a hurricane can move at a variety of speeds. Previous studies have shown that many cells move at roughly the azimuthal mean wind, while numerous others move at slower speeds. Two potential mechanisms responsible for these slower speeds are: 1) propagation and/or preferential growth along a near-surface boundary, and 2) vortex-Rossby waves (VRWs). Regarding the latter, VRWs are assumed to result from the convective cells via convergence and stretching of background vorticity. Since VRWs theoretically move at some fraction of the local azimuthal mean wind, slow moving convective cells may thus be manifestations of VRWs. In this study we perform a census of convective cells motions within an intense hurricane, and use these results to infer the frequency to which the above mechanisms modulate cell motion.

This study utilizes an extensive dataset composed primarily of airborne NOAA P-3 lower fuselage radar data, taken every thirty seconds, from Hurricane Guillermo (1997). The data is spread over ten passes through the storm's inner core and is supplemented with both the flight-level winds (out to a radius of 100km) and dual-Doppler winds (out to a radius of 60km). The SOLO-II software was used to track numerous convective cells, recording their location and maximum radar reflectivity while each cell remained a distinct entity. Taking this data, along with the aforementioned flight-level winds and dual-Doppler winds, the convective cell motions will be compared to azimuthal mean tangential winds and the expected motions for VRWs. Statistical analysis will then be performed to determine which motions are most common. A synopsis of our results and their comparison with previous studies will be presented at the conference.

Poster Session 1, Student Conference General Poster Session
Sunday, 20 January 2008, 5:30 PM-7:00 PM, Exhibit Hall B

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