5.2
Relationships between baroclinically-generated horizontal vorticity and mesocyclone intensity as revealed by simple adjoint wind retrievals using WSR-88D data
Janelle M. Janish, CIMMS and NOAA/NSSL, Norman, OK; and K. K. Droegemeier and J. Gao
Horizontal vorticity generated baroclinically along the leading edge of the forward flank cold pool of supercell storms is known to be a source of low-level vertical vorticity within mesocyclones and may play a role in tornadogenesis. Diagnosing the horizontal vorticity requires the three-dimensional low-level winds, which are not available from a single Doppler radar. We therefore apply in this study a simple adjoint technique to retrieve, from a time series of WSR-88D radial winds associated with an observed tornadic supercell storm, the low-level horizontal wind field. We then compute the horizontal vorticity and relate it to mesocyclone intensity. This method is applied to a tornadic supercell that produced an F4 tornado and was observed with the KNQA (Memphis, TN) WSR-88D on November 27, 1994 in Germantown, Tennessee. The storm is examined for a period from one hour prior to tornado time through the lifetime of the tornado. We demonstrate the benefits of using the simple adjoint technique by computing horizontal vorticity using only the radial wind field and using the retrieved horizontal wind field.
Session 5, Radar Applications
Tuesday, 13 August 2002, 10:30 AM-12:00 PM
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