Evaluation of a regional air quality forecast model for tropospheric NO2 columns using the OMI/AURA satellite tropospheric NO2 product.

Results from a regional air quality forecast model, AIRPACT-3, are compared to OMI tropospheric NO₂ integrated column densities for an 18 month period over the Pacific Northwest. AIRPACT column densities were well correlated with cloud-free monthly averages of tropospheric NO₂ (R=0.75) to NASA retrievals for months without wildfires, but were poorly correlated with significant model overpredictions (R=0.21) for months with wildfires when OMI and AIRPACT were compared over the entire domain. AIRPACT forecasted higher NO₂ in some US urban areas, and lower NO₂ in many Canadian urban areas, when compared to OMI. There are significant changes in results after spatially averaging model results to the daily OMI swath. Also, it is shown that applying the averaging kernel to model results in cloudy conditions has a large effect, but applying the averaging kernel in cloud free conditions has little effect. The KNMI and NASA retrievals of tropospheric NO₂ from OMI (collection 3) are compared. The NASA product is shown to be significantly different than the KNMI tropospheric NO₂ product, i.e. July 2007 (R=0.60) and January 2008 (R=0.69). [ABSTRACT FROM AUTHOR]