Long-term cloud and precipitation observations with the ARM w-band cloud radars

The Atmospheric Radiation Measurement (ARM) program has continuously operated W-band ARM cloud radars at the ARM Climate Research Facility (ACRF) fixed site located in Oklahoma, USA and at the ARM Mobile Facility in Niamey, Niger (2006) and Black Forest, Germany (2007) for the purpose of collecting a climatically relevant dataset on the vertical distribution of clouds. The 95 GHz radars are zenith-pointing with dual polarization, collecting both Doppler moments and Doppler spectra. At the Oklahoma site, operations began in December 2005 and are ongoing in concert with the full suite of ACRF instrumentation designed for the long-term monitoring of clouds, radiation, atmospheric state and aerosols. In Niamey, W-band radar along with the ARM Mobile Facility instrumentation, which includes a baseline set of observations similar to those of the ACRF fixed sites, are available from March to December 2006, capturing both the dry season and the summer monsoon. Here we present a summary of observations from the W-band ARM cloud radars combined with collocated micropulse lidar and ceilometer observations describing the vertical distribution of clouds and precipitation in the column above the sites. In addition, measurements from a collocated vertically-pointing 35 GHz Millimeter Cloud Radar are also available at the Oklahoma site. We will present some preliminary results of long-term, dual-frequency analysis of cloud properties over the Oklahoma site.