An Analysis of the Three-Dimensional Wind Field of Hurricane Ivan (2004) Using Radar Data
Michael D. Williams, The University of Alabama, Huntsville, AL; and K. Knupp
During the landfall of Hurricane Ivan (2004) significant changes in intensity occurred, the origins of which remain to be determined. A synoptic analysis reveals significantly drier air to the west of the system, yet it is hypothesized that other factors may have contributed to the rapid weakening of the hurricane in the hours prior to landfall. A theory exists linking the existence of landfalling stratiform rainbands to the production of cool, dry mesoscale downdrafts. It is thought that this cool, dry air is vertically advected on scales large enough to cause weakening of the system if advected into the inner core region (within 100 km of the eye). It is the goal of this research to focus solely on the existence and strength of these downdrafts. For this research the Mobile, Alabama WSR-88D radar is used in concert with a DOW radar located just north of Orange Beach, Alabama to conduct a dual-Doppler analysis. This analysis will concentrate heavily on areas in southern Alabama and extreme northwest Florida during the the time period 1700 UTC 15 September 2004 to 0600 UTC 16 September 2004 (50 minutes prior to landfall) . Separate Extended Velocity Azimuth Display (EVAD) analyses are conducted on both the WSR-88D and the DOW radars to determine the aerial averaged wind field within the vicinity of each of these radars. Because the results of the EVAD analyses are aerial averages the areas of interest for the EVAD analyses are quite small compared to that of the dual-Doppler analysis. Comparisons of results derived from each of these analyses will help identify and quantify specific downdraft regions.
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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