Cloud and Drizzle Separation for Vertical Pointing W-band Radar Data

Abstract:

The ability to separate cloud and drizzle returns in radar signals is a key step for advancing cloud and precipitation studies, particularly in warm rain formation. A number of studies have used the properties of Doppler Spectra (e.g., skewness) and shown some success, but the cloud-drizzle separation remains challenging for moderate and heavy drizzling conditions. To develop a robust separation method, we introduce the parametric time domain method (PTDM). This method has been used to separate clutter for weather radar observations, but it is used to separate cloud and drizzle for the first time. The main advantage of the PTDM method is that cloud and drizzle parameters are estimated simultaneously. It does not suppress or remove any part of the Doppler spectra, avoiding any alteration that might lead to significant errors in cloud/drizzle attributions. We will detail PTDM and demonstrate its performance using the vertical pointing W-band cloud radar from the Atmospheric Radiation Measurement (ARM) program Mobile Facility deployment at the Azores in 2009–2010. By combining PTDM with a sophisticated retrieval method, we will also show the corresponding cloud and drizzle microphysical properties and associated uncertainty.