Atmospheric Measurement Techniques Discussions | 2019
Estimation of Liquid Water Path in Stratiform Precipitation Systems using Radar Measurements during MC3E
Abstract
Abstract. In this study, the liquid water path (LWP) in stratiform precipitation systems is retrieved, which is a combination of rain liquid water path (RLWP) and cloud liquid water path (CLWP). The retrieval algorithm uses measurements from the vertically pointing radars (VPRs) at 35 GHz and 3 GHz operated by the U.S Department of Energy Atmospheric Radiation Measurement (ARM) and National Oceanic and Atmospheric Administration (NOAA) during the field campaign Midlatitude Continental Convective Clouds Experiment (MC3E). The measured radar reflectivity and mean Doppler velocity from both VPRs and spectrum width from the 35\u2009GHz radar are utilized. With the aid of the cloud base detected by ceilometer, the LWP in the liquid layer is retrieved under two different situations: (I) no cloud exists below the melting base, and (II) cloud exists below the melting base. In (I), LWP is primarily contributed from raindrops only, i.e., RLWP, which is estimated by analyzing the Doppler velocity differences between two VPRs. In (II), cloud particles and raindrops coexist in the liquid layer. The CLWP is estimated using a modified attenuation-based algorithm. Two stratiform precipitation cases (20 May 2011 and 11 May 2011) during MC3E are illustrated for two situations, respectively. With a total of 14 hours of samples during MC3E, statistical results show that the occurrence of cloud particles below the melting base is low (8\u2009%), however, the mean CLWP value can be up to 0.87\u2009kg\u2009m −2 , which is much larger than the RLWP (0.22\u2009kg\u2009m −2 ). When only raindrops exist below the melting base, the averaged RLWP value is larger (0.33\u2009kg\u2009m −2 ) than the with cloud situation. The overall mean LWP below the melting base is 0.39\u2009kg\u2009m −2 for stratiform systems during MC3E.