Extended Abstract (512K)14.6
Radar refractivity applications for convective initiation forecasting and observations of the convective boundary layer
David Bodine, Atmospheric Radar Research Center, School of Meteorology, University of Oklahoma, Norman, OK; and B. L. Cheong, P. L. Heinselman, R. D. Palmer, and D. S. Michaud
Previous studies have shown that the lack of high-resolution surface moisture data is a major limitation in forecasting the timing and location of convective initiation. Convective initiation is dependent on small-scale structures, such as horizontal convective rolls and eddies, which cannot be adequately resolved by the Automated Surface Observing System (ASOS) stations. Radar refractivity data provide high spatial and temporal resolution moisture data near the surface out to an approximate 50 km radius from the radar, depending on terrain. As part of a recently funded three-year NSF project, radar refractivity data will be collected on seven Doppler radars in Oklahoma, including two operational WSR-88Ds, the Phased Array Radar, and the four CASA, X-band radars. As a result, the possible coverage will be increased significantly providing a nearly complete swath of refractivity measurements over southwest Oklahoma.
KTLX (Oklahoma City) refractivity data from the 2007 and 2008 experiments showed distinct advantages over surface observations and reflectivity data for boundary detection. Several refractivity cases demonstrated that the refractivity data could allow forecasters to locate boundaries and areas of moisture pooling which contributed to convective initiation. Refractivity data can also reveal small-scale structures in the planetary boundary layer. Cross-correlation analyses for days with a well-defined mixed layer showed that the velocity of the near-surface moisture change field was approximately the same as the mean boundary layer velocity vector. Thus, circulations throughout the boundary layer depth appear to cause the near-surface moisture changes. In addition to these applications, future plans for convective initiation studies and data assimilation of refractivity data will be discussed.
Session 14, Radar Applications - Session III
Thursday, 15 January 2009, 1:30 PM-3:00 PM, Room 122BC
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