Accurate measurements of precipitation Drop-Size Distributions (DSD) are fundamental for understanding the processes governing cloud microphysics and improving cloud representations in numerical models. Despite their importance, the small-scale variability of DSDs and their interaction with air drafts remains unknown, especially at scales unresolved by most active and passive remote sensing instruments.

In this paper, a multi-frequency ground-based radar facility (W, X and UHF-band) for precipitation studies is described. Using a 3-mm wavelength Doppler radar operating at vertical incidence, the Mie oscillations in the backscatter are often observed in the Doppler spectrum and provide a fingerprint of the raindrop distribution and accurate air velocities (± 0.1 ms-1) within precipitation. A proposed X-band radar operating at vertical incidence will provide unattenuated reflectivity profiles for scaling the retrieved DSDs or providing PPI and RHI scans of precipitating systems as they pass overhead. In addition, a 915-MHz wind profiler will provide horizontal winds to facilitate the interpretation of the observed structures. Networks of rain gauges and surface meteorology instruments and the Miami WSR-88D radar will complement the local radar observations made from a site near Key Biscayne, Florida. The facility will provide high temporal and spatial resolution profiles of vertical air motion and DSDs in stratiform and convective precipitation. The feasibility and scientific utility of this approach is demonstrated by observations using the University of Miami 94 GHz Doppler radar, a 915 MHz wind profiler, and an S-Band radar provided by NOAA?s Environmental Technology Laboratory in place of the proposed X-band radar. Observations starting in June 2001 from these systems provide examples of DSD and vertical velocity retrievals obtained from several precipitation events.