Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

摘要

This paper presents a methodology for ice water content (IWC) retrieval from a dual-polarization side-looking X-band airborne radar. Measured IWC from aircraft in situ probes is weighted by a function of the radar differential reflectivity (Z(dr)) to reduce the effects of ice crystal shape and orientation on the variation in IWC - specific differential phase (K-dp) joint distribution. A theoretical study indicates that the proposed method, which does not require a knowledge of the particle size distribution (PSD) and number density of ice crystals, is suitable for high-ice-water-content (HIWC) regions in tropical convective clouds. Using datasets collected during the High Altitude Ice Crystals - High Ice Water Content (HAIC-HIWC) international field campaign in Cayenne, French Guiana (2015), it is shown that the proposed method improves the estimation bias by 35% and increases the correlation by 4% on average, compared to the method using specific differential phase (K-dp) alone.