Interactions of Cumulus Convection and the Boundary Layer at the Southern Great Plains ACRF, Final Report.

摘要

The DOE ARM program has promoted understanding of cumulus convection by producing high- quality single-column model observational datasets that allow one to run and evaluate singlecolumn models and cloud-resolving models based on observed large-scale conditions. The cloud and radiation fields produced by such simulations can then be compared to measurements by an ARM cloud profiling radar, as well as to satellite-based measurements. This is an excellent approach for stratiform cloud systems, but not for convective cloud systems, which are inadequately sampled by the cloud profiling radars. However, the existing observational systems at the ARM Southern Great Plains (SGP) Atmospheric Climate Research Facility (ACRE) can be used to provide a much more extensive spatial sampling of convective cloud systems. Because convective cloud systems generally have strong interactions with boundary layer circulations and thermodynamics, the boundary layer wind and thermodynamic fields contain a great deal of information about convective cloud systems and their interactions with the boundary layer. We developed new methods to retrieve information about convective cloud systems from mesonet and precipitation data. Our data products are based on 15 years of 5-minute Oklahoma Mesonet data and hourly Arkansas Basin River Forecast Center (ABRFC) gridded precipitation data and include (1) statistics of the surface divergence field from which estimates of near-cloud-base updraft and downdraft mass fluxes can be made, and (2) catalogs of (a) frontal passage properties (time and location, temperature drop and pressure rise), and (b) convective cold pool properties (time and location, size, duration, temperature drop and pressure rise).