Cloud and Precipitation Microphysical Properties of Warm Season Mesoscale Convective Systems

Abstract

Mesoscale convective systems (MCSs) are the largest convective storms and consist of active convective towers, expansive stratiform regions, and large anvil regions. Ice melting is a dominant rainfall formation process in the stratiform precipitation associated with MCSs, and the vertical profiles of microphysics determine the radiation budget and redistribute energy in the atmosphere. However, the MCS cloud and precipitation microphysical properties have neither been fully understood nor characterized in models accurately. Developing targeted retrievals from long-term observations would be beneficial in understanding the cloud and precipitation microphysical properties within MCSs. There are two major objectives for this dissertation. The first one is to develop new retrieval algorithms to estimate the cloud and precipitation microphysical properties of MCSs. The second one is to make use of the new retrievals to evaluate satellite product/retrievals and improve our understanding on the spatiotemporal characteristics of warm season MCS precipitation and ice cloud microphysical properties. In our study, new retrieval algorithms are developed to estimate the MCS cloud and precipitation microphysical properties using radar measurements and some empirical relationships derived from aircraft in situ measurements during the Midlatitude Continental Convective Clouds Experiment (MC3E). The MC3E was conducted by the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) and the National Aeronautics and Space Administration (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program at the ARM Southern Great Plains (SGP) site during April-June 2011. Unique precipitation and cloud microphysical products are generated, which include the MCSs’ ice water path (IWP), liquid water path (LWP), rain water path (RLWP), vertical distributions of ice water content (IWC), and rain liquid water content and path (RLWC and RLWP) during MC3E. The retrieved vertical distributions of IWC and RLWC can help improve our understanding of the cloud-precipitation transition processes. As one application of these unique retrievals for MCSs, IWPs retrieved from satellite observations are evaluated. It is found that radar and satellite retrievals have similar probability distribution functions and small mean differences in anvil regions, however, large differences and low correlations exist in stratiform rain areas. To better understand the spatiotemporal variations of warm season MCSs’ precipitation and ice cloud microphysical properties, a new database of MCSs’ ice cloud microphysical properties has been generated during the period 2010-2012. There are different distributions of precipitation and IWP in summer and spring. Composite evolutions of MCS precipitation and IWP could be explained by the MCS stratiform precipitation formation processes during spring and summer seasons.