Airborne Radar Observation of A Major Winter Storm: Use of Dual-frequency and Polarimetric Measurements in Studies Cloud Structures and Processes

This paper presents analysis of in-situ and airborne radar polarimetric measurements of a major winter storm sampled on March 1, 2007 during the Canadian CloudSat and CALIPSO Validation Project (C3VP). The Airborne component of the C3VP field project (www.c3vp.org) was conducted in Ontario and Quebec, Canada between October 2006 and March 2007 using the NRC Convair-580 aircraft. The near-coincident in-situ cloud microphysics data and the NRC W and X-band radar (NAWX) at close range are used to infer the cloud structure and dominant microphysical processes. Fig. 1 shows the Convair altitude and flight level temperature and samples of PMS 2D-C images measured as the aircraft sampled all ice regions first at higher altitude and then descended to sample the storm center. The Dual Frequency Ratio (DFR) of the NAWX radar is computed and correlated with the microphysical measurements. The DFR ratio varies from near 0 dB, in regions dominated by small ice crystals (< 1 mm), to over 20 dB where the dominant process is aggregation or in rain. In the liquid layer, the W-band signal was heavenly attenuated and the DFR from the side-looking data is correlated with the total water content measured by the in-situ data. In addition to the DFR, the polarimetric measurements of the W-band data are used to characterize the dominant crystals types and cloud structure.