Terminal fall velocity from a Doppler radar performing RHI scannings

Range Height Indicator (RHI) sequences performed by radars provide quick successive vertical cross-sections on meteorological systems. Using information from radial wind measurements and their variations allows to obtain estimates of the horizontal component of the wind and of the terminal fall velocity of hydrometeors. The method was tested through simulations and applied to data gathered during the Mesoscale Alpine Programme (MAP), an international programme devoted to the study of mesoscale atmospheric and hydrologic processes over complex terrain. Data were obtained from the American S-band Doppler / polarimetric S-POL radar of NCAR deployed in the Lago Maggiore Target Area during MAP. For the present study, we focus on IOP2a (17-18 September 1999) of the MAP field phase, which corresponds to the passage of an intense squall line over the Multiple-Doppler coverage area.