Estimating vertical velocity in a hurricane with single-dopplar radar data

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.