NO2 columns in the western U.S. observed from space and simulated by a regional chemistry model and their implications in NOx emissions.

In the western U.S., there are many isolated sources of NOx emissions such as power plants, cities, and highways. Thus, errors in bottom-up NOx emissions from various sectors could be evaluated separately with satellites and atmospheric chemistry models in this part of the U.S. We carried out simulations with the Weather Research and Forecasting-Chemistry model (WRF-Chem) for the western US domain during the summer of 2005. Model NO2 columns are compared with SCIAMACHY and OMI satellite observations. The sensitivities of simulated NO2 columns to chemical mechanism and scalar-advection scheme along with the sensitivities of satellite retrievals to several assumptions are examined. Agreement between the satellite data and the model results will be summarized for each type of source.