2A.4
Estimating vertical velocity in a hurricane with single-dopplar radar data
Jin-Luen Lee, NOAA/FSL, Boulder, CO; and W. C. Lee and A. E. MacDonald
A vorticity method utilizing high temporal resolution wind measurements from a single-Doppler radar is used to derive the horizontal divergence/vertical velocity in a hurricane. In this method, the horizontal divergence/vertical velocity is inferred dynamically from the vorticity variations in space and in time based on the vorticity equation. The ground-based velocity track display (GBVTD) retrieves the vorticity field in the tropical cyclone (TC) based on single-Doppler radar data. The GBVTD-derived vorticity field is available in 6-min intervals and 1-km spatial resolution. With the GBVTD-derived high temporal and spatial vorticity variations, we have applied the vorticity method to derive the horizontal divergence/vertical velocity in Hurricane Danny, which hit the Alabama coast in 1979. The derived divergence and vorticity fields are used to compute the total wind and the balanced dynamical/mass fields using the mesoscale bounded derivative initialization (BDI). A balanced TC derived from BDI and the vorticity method based on GBVTD-derived winds from a single-Doppler radar can be used to initialize hurricane models for the improvement of the velocity track and intensity forecast of TCs.
Session 2A, Tropical Cyclones (Parallel with Session 2B)
Thursday, 19 July 2001, 4:00 PM-5:30 PM
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