Characterization of Hydrometeors in Sahelian Convective Systems with an X-Band Radar and Comparison with In Situ Measurements. Part II: A Simple Brightband Method to Infer the Density of Icy Hydrometeors

摘要

A simple scheme that is based on the shape and intensity of the radar bright band is used to infer the density of hydrometeors just above the freezing level in Sahelian mesoscale convective systems (MCS). Four MCS jointly observed by a ground-based X-band radar and by an instrumented aircraft as part of the Megha-Tropiques algorithm-validation campaign during August 2010 in Niamey, Niger, are analyzed. The instrumented aircraft (with a 94-GHz radar and various optical probes on board) provided mass-diameter laws for the particles sampled during the flights. The mass-diameter laws derived from the ground-radar vertical profile of reflectivity (VPR) for each flight are compared with those derived from the airborne measurements. The density laws derived by both methods are consistent and encourage further use of the simple VPR scheme to quantify hydrometeor density laws and their variability for various analyses (microphysical processes and icy-hydrometeor scattering and radiative properties).