Investigation of Warm Season Convective Cloud and Precipitation Properties through the Integrative Analysis of Aircraft In-situ Measurements, Ground-based Observations, and WRF Simulations

Abstract

Mesoscale convective systems (MCSs) can be separated into a precipitation portion which includes convective rain (CR) and stratiform rain (SR) and a non-precipitation canopy portion, the former dominates much of warm season (April - September) intense rainfall over the mid-latitudes, while the latter plays a significant role in the atmospheric radiation budget due to the its extensive spatial coverage. The convective rain (≥5 mm hr-1) portion features the most intense rainfall rate compared to the long-lasting stratiform rain (<5 mm hr-1) portion with large area coverage, which strongly corresponds to the high flood risk level. In order to improve the understanding of cloud-precipitation microphysical properties and their interactions for the cloud-resolving model, the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) conducted a field campaign in a collaborative effort with NASA’s Global Precipitation Measurement (GPM) mission Ground Validation (GV) program, the Midlatitude Continental Convective Clouds Experiment (MC3E), at the ARM Southern Great Plains (SGP, 36° 36' 18" N, 97° 29' 6" W) site from April to June 2011. During the MC3E field campaign, the University of North Dakota (UND) Citation II research aircraft carried out the major in situ measurements of cloud microphysical properties. By separating the MCSs into ice-phase layer and liquid-phase layer, this study investigates microphysical properties at each layer using the measurements collected by UND Citation II aircraft. For ice-phase layer, the focus is on the correction of cloud ice water content (IWC) and the reconstruction of particle size distribution (PSD) based on multiple sensors measurements. For liquid-phase layer, this study concentrates on the better parameterization of raindrop size distribution (DSD) and its application in radar-based rain rate retrieval. In addition to the investigation of MCSs’ microphysical properties, another major part of this dissertation regards the long-term statistical analysis of the warm season (April-September) precipitation over the Great Plains (GP). Specifically, two subdomains, namely the Southern Great Plains (SGP, 99.985o W to 94.985o W, 34.66o N to 38.66o N) and Northern Great Plains (NGP, 100.75o W to 95.75o W, 45o N to 49o N) are selected. By using Self-Organizing-Map (SOM) method, a total of 300 convective systems during the period 2007-2014 are objectively classified into 6 classes according to the integrative analysis of synoptic characteristics over each sub-domain respectively. Despite the difference in regional climatology, both regions demonstrate prominent seasonal contrast in dominant synoptic patterns. The early summer convective systems are more impacted by the extratropical cyclone, while the late summer/early fall events are strongly associated with subtropical ridge. Based on the SOM results, the real-time weather forecast product generated by the National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory (NSSL) is evaluated using National Centers for Environmental Prediction (NCEP) Stage IV data for each individual SOM class over each region.