Retrieval of cloud microphysical parameters using the NOAA/PSD W-band cloud radar from R/V Ronald H. Brown during the VOCALS-REx field program

The NOAA Physical Science Division deployed a new pitch-roll stabilized, vertically pointing W-band (94 GHz) Doppler cloud radar on the NOAA research vessel Ronald H. Brown during the VOCALS-Rex field program in fall 2008 in the stratocumulus region off the coast of Chile. The radar operated at full sensitivity on Leg-2 (November 8-30, 2008). The radar produced profiles of full Doppler spectra and the first three moments of the spectral peak at 0.3 s time intervals; the vertical resolution is 25 m. Pitch-roll stabilization allows Doppler measurement of vertical motion without tilt-contamination by horizontal winds; ship heave is measured independently and subtracted from the radar vertical velocity to yield very accurate particle vertical motions. In this paper we describe the results of processing the radar moments in one-hour blocks to retrieve cloud and drizzle microphysical parameters using the method of Frisch, Fairall, and Snider, JAS1995. Additional inputs from a lidar ceilometer and a microwave radiometer are used. For cloud, profiles of liquid water and mean cloud drop radius are obtained; for drizzle profiles of liquid water, mean drizzle drop radius, and rainrate are obtained. Cloud microphysics processing is only possible in non-drizzling cases. The results are compared to analyses from the EPIC2001 field program in the same location.