Wednesday, 15 January 2020
Hall B1 (Boston Convention and Exhibition Center)
Clouds and precipitation are key components in the hydrological and energy cycles of the climate system. Our study investigated the characteristics of Ice Cloud-Precipitation of warm season Mesoscale Convective Systems (MCSs) over the Great Plains. In this study, the MCSs are tracked using high-resolution radar and satellite observations over the U.S. Great Plains during April to August from 2010 to 2012. The spatiotemporal variability of MCSs precipitation is then characterized using Stage-IV product. We found the spatial variability and nocturnal peaks of MCSs’ precipitation are primarily driven by the MCSs occurrence and not the precipitation intensity. The tracked MCSs are further classified into convective core (CC), stratiform rain (SR) and anvil clouds regions. The spatial variability and diurnal cycle of precipitation in the SR regions of MCSs are not as significant as those of MCSs’ precipitation. In the SR regions, the high-resolution, long-term ice cloud microphysical properties [ice water content (IWCs) and paths, IWPs] are provided. The IWCs decrease with height generally and the IWCs and IWPs are consistent with their precipitation counterpart, where the precipitation during summer and over Southern Great Plain are higher than those during spring and over Northern Great Plain. Comparing the peaks of MCSs’ precipitation and IWPs from the diurnal cycles and their composite evolutions, it is found when using the SR IWP peak as a reference, the heaviest precipitation in the MCSs convective core occurs earlier, while the strongest SR precipitation occurs later. The shift of peaks in MCSs CC and SR precipitation related to the SR IWP could be explained by the stratiform precipitation formation process. The relations between IWP and precipitation are different at MCSs genesis, mature and decay stages, and the transition from ice to precipitation are highly related to the low-level humidity.
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