Impact of Lightning Data Assimilation and Subgrid-Scale Cloud-Radiation Interaction on Regional Meteorology and Atmospheric Composition During DISCOVER-AQ TX Period

The assimilation of total lightning observations is used to help initiate convection within the Kain-Fritsch (KF) scheme at 36- and 12-km resolution within the Weather Research and Forecasting (WRF) numerical model during the DISCOVER-AQ 2013 Texas period. Two procedures for Lightning Data Assimilation (LDA) are tested and compared (Mansell 2007 and Fierro 2012). Fierro's procedure is tested to determine whether it can be used at these relatively coarse resolutions. When a successful simulation is obtained with LDA, we will evaluate the impact of sub-grid scale cloud-radiation interactions on surface short wave radiation. The study utilizes data from the Earth Networks Total Lightning Network at 12 km grid spacing to nearly match the resolution (9 km) of the Geostationary Lightning Mapper (GLM) that will be on the upcoming GOES-R satellites. Since subgrid-scale convection attenuates shortwave radiation leading to suppressed convection, decreased surface precipitation as well as other meteorological parameter changes, e.g. planetary boundary layer (PBL) height changes, we will conduct a suite of numerical experiments to compare the sensitivity of meteorological parameters to the control runs that do not include lightning data assimilation and/or subgrid cumulus cloudiness. The WRF simulations will be compared with NCEP stage IV hourly precipitation observations. Furthermore, we will examine the chemical impact from the meteorological changes (PBL height et al.) using a regional chemical transport model (CMAQ). Finally, we will compare with DISCOVER-AQ flight observation data and evaluate how well this off-line CMAQ simulation driven by WRF with the KF scheme simulates the effects of regional convection on lower troposphere composition, particularly distributions of CO, NOx and ozone.