Application of satellite data in a regional model to improve long-term ozone simulations

To investigate an alternative technique of providing background and transboundary transport inputs for ozone (O3) simulations on a regional scale, the EPA’s Community Multiscale Air Quality (CMAQ) model was integrated with high spectral resolution data from the Tropospheric Emission Spectrometer (TES) aboard the NASA’s Aura satellite. This study presents a comprehensive model evaluation of O3 for the entire year of 2009 over the contiguous United States with a focus on the State of Texas using both ozonesonde and ground measurements. While improving model performance in the upper atmosphere, CMAQ’s initial and boundary conditions (IC/BC) derived from the original TES data do not improve model performance in the troposphere because the satellite data exaggerated concentration of tropospheric O3.With a 10-ppb deduction of O3 concentration from TES, the IC/BC derived from the adjusted TES improves model performance from ground level through the upper atmosphere. The mean bias of daily maximum 8-h average concentration of O3 (MDA8) from the ground monitored in Texas decreased from 7 ppb to 4 ppb. Model results also show small influences of O3 from the upper troposphere on the concentrations at the ground level. With a complete exclusion of stratospheric layers, changes of annual mean MDA8 of O3 concentrations at ground-level were smaller than 1.1 % in Dallas and Houston. In addition, limitations of satellite data are discussed and recommendations are provided regarding the future application of satellite data in regional O3 simulations.