Thursday, 24 January 2008
Investigation of a severe microburst near Phoenix, Arizona as seen by a mobile Doppler radar and the KIWA WSR-88D
Exhibit Hall B (Ernest N. Morial Convention Center)
A Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) was deployed near Phoenix, Arizona during the summer of 2004. The goal was to capture a severe microburst at close range to understand the low-altitude wind effects on power lines in support of Salt River Project utilities maintenance. On 28 July, a severe storm formed along the Estrella Mountains south of Phoenix and moved south of the SMART-R as well as the National Weather Service's KIWA WSR-88D. Several microburst pulses were observed and a wind gust of 67 mph was reported. The radar data illustrate the fine-scale structure of the microburst with the SMART-R's higher resolution data showing higher Doppler velocities by 3-4 m s-1 than the KIWA radar. SMART-R wind shear values were overall greater as well with the finer resolution of the SMART-R revealing finer details in the surface outflow wind structure. The evolution of the outflow was very rapid with the 6 min KIWA scans intervals being too course to sample the detailed evolution. The SMART-R scans were at 3-5 min intervals and still had difficulty resolving the event. The microburst environment, displayed characteristics of both low-reflectivity microbursts typical of the High Plains of Colorado, and high-reflectivity microbursts observed in more humid environments.
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