Radar wind profiler investigations into MCSs characteristics

Wednesday, December 12, 2018 - 11:05
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Mesoscale convective systems (MCSs) regulate the global energy cycle through their extensive cloud coverage and the exchange of latent heat, and are associated with a large proportion of extreme precipitation events. The dynamic and thermodynamic processes within MCSs are complex, exhibiting a variety of convective and stratiform cloud characteristics in tropical and continental regions. This study contrasts properties of extended ground-based radar wind profiler (RWP) mature MCS datasets collected over tropical and mid-latitude regions. Multi-instrument datasets from DOE Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Site in Oklahoma, U.S. (16 events) and the ARM mobile deployment to Manaus, Brazil (GoAmazon2014/5, 46 events) are covered.

Tropical and mid-latitude MCSs both show a deep leading convective updraft with comparable precipitation rates and a broader trailing stratiform precipitation regions. Surface cold pools developed beneath the convective cores and are associated with sharpest drops (∼10 K) in surface equivalent potential temperature (θe) during the system passage. The θe drops at the surface have a robust relationship with precipitation rate and probability across regions, suggesting their potential use in model evaluations and downdraft parameterization improvement. Compared to tropical MCSs, mid-latitude MCSs are consistent in displaying an upper-level leading anvil, and higher reflectivity in trailing stratiform (more developed aggregation processes). SGP MCSs also suggest more intense, but narrower updrafts in the middle-upper troposphere, peaking at higher altitudes (10 km, on average), as well as deeper and stronger precipitation-driven downdrafts that could originate from mid-levels (up to 6 km) if substantial mixing occurs (χ = 0.34 km-1). SGP datasets also indicate drier and colder cool pools at the surface.

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