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

Abstract. 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 are well correlated (r=0.75) to cloud-free (<35%) retrievals of tropospheric NO₂ for monthly averages without wildfires, but are poorly correlated (r=0.21) with significant model over-predictions for months with wildfires when OMI and AIRPACT are compared over the entire domain. AIRPACT predicts higher NO₂ in some northwestern US urban areas, and lower NO₂ in the Vancouver, BC urban area, when compared to OMI. Model results are spatially averaged to the daily OMI swath. The Dutch KNMI (DOMINO) and NASA (Standard Product) 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. The average difference in tropospheric columns, after applying the averaging kernels of the respective products to the model results, is shown to be larger in the summer (±50%) than winter (±20%).