An Analysis of Deep Convective Transport in May 21, 2012 DC3 Alabama Thunderstorms Using Results from WRF-Chem Simulations
Friday, 19 December 2014
Deep convective thunderstorms play an important role in the vertical redistribution of trace constituents in the atmosphere through vertical transport. This study focuses on airmass thunderstorms which occurred in northern Alabama on May 21, 2012 during the Deep Convective Clouds and Chemistry (DC3) field campaign. Two aircraft (NASA DC-8 and NCAR G-V) sampled inflow and outflow of the convective storms. WRF-Chem simulations of the same event are conducted on 3 nested domains at a cloud-parameterizing scale (15 km horizontal grid) and cloud-resolving scales (3 km and 0.6 km horizontal gird). Lightning data assimilation with a smooth nudging function is used to improve the WRF-Chem simulations of thunderstorm location and structure. Gridded total flashes from the North Alabama Lightning Mapping Array (NALMA) and Earth Networks Total Lightning Network (ENTLN) are assimilated by the model every 10 minutes. Compared with the NEXRAD radar reflectivity, the model-simulated thunderstorms capture the placement, structure and intensity of the real storms fairly well, but the storms decay faster than those in the observations. The model-simulated vertical distributions of trace gases within the storm and surrounding the storm are compared with measurements from the DC-8 and G-V aircraft in the storm inflow and outflow regions. Model-derived CO mixing ratios and vertical velocities are used to estimate transport from the boundary layer to the upper troposphere, and these results are compared with those from other more intense convective systems observed in DC3.