ON THE USE OF A CLOUD SENSING RADAR TO MEASURE DRIZZLE PARAMETERS

The WPL K-band radar is sensitive enough to detect cloud drops and measure cloud drop motion. One application of the radar is to study the effects of drizzle in stratus clouds. The present study took place during the ASTEX program. The radar was located on Porto Santo, in the Madeira Archipelago. During some of this time, there were stratus clouds and drizzle. We examined one such time period with the radar in a vertical pointing mode.

Using a simple 3 parameter log-gaussian model for the drizzle drops, we are able to relate these three parameters to the zeroth, first and second Doppler velocity moments. We average these measurements over a 25 minute period to eliminate much of the vertical air motion in the calculations of the model parameters.