CMAQ Simulation of the January–February 2013 DISCOVER-AQ Field Campaign Period in the San Joaquin Valley of California and Comparison with Observations

The second deployment of the NASA Earth Venture – 1 DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field program took place in January and February 2013 in the San Joaquin Valley of California. This region frequently experiences large particulate matter concentrations in the wintertime. Over 170 lower tropospheric profiles of aerosol types and optical and microphysical properties, as well as trace gases (e.g., O3, NO, NO2, HCHO, CO, HNO3, and selected VOCs) were observed by the P-3B aircraft over a set of existing air quality monitoring stations, which were upgraded to include AERONET sun photometers and Pandora UV/Vis spectrometers. In addition, over 150 missed approaches were conducted at a set of airports in the region to obtain observations as close to the surface as possible. A King Air aircraft conducted remote sensing with the High Spectral Resolution Lidar (HSRL) for aerosols and the Airborne Compact Atmospheric Mapper (ACAM) instrument for trace gases. The deployment period was simulated with the CMAQ v5.0 model driven by WRF meteorology and evaluated using in-situ data collected by the NASA P-3B aircraft, as well as the AERONET and HSRL aerosol optical depth data. The evaluation was conducted using output from a 4-km resolution domain and focused on the ability of the model to simulate regional aerosol. The influence of terrain-forced flows on the aerosol and trace gas concentrations will be investigated.