Circular depolarization ratio and Doppler velocity measurements with a 35-GHz radar during the Cooperative Convective Precipitation Experiment

All aspects of atmospheric convection on the North American High Plains were studied during the Cooperative Convective Precipitation Experiment. This 3-month experiment conducted near Miles City, Montana, during the summer of 1981 made use of 14 instrumented aircraft and a network of seven Doppler radars. One of these radars, the National Oceanic and Atmospheric Administration/Wave Propagation Laboratory K band (35 GHz) radar had dual-polarization capability. The circular depolarization ratio (CDR) from the log receiver of this radar was measured in many different meteorological situations, including nonprecipitating clouds, convective storms with light precipitation, and severe hail storms. The analysis discussed here focuses on measurements near the melting layer where a sharp peak in the CDR profile was observed. A method for classifying particles on the basis of their fall speeds is related to measurements of CDR near this level for more than a 1-hour period. Preliminary aircraft data are used as an aid in the interpretation.