Abstract

We examine spatial variations in the weekday-weekend pattern of NO 2 over the Los Angeles metropolitan area using the Ozone Monitoring Instrument and then compare the observations to calculations using the WRF-Chem model. We find that the spatial pattern of the weekday-weekend variations of the NO2 column in the model is significantly different than observed. A sensitivity study shows that the contrasting spatial pattern of NO2 on weekdays and weekends is a useful diagnostic of emissions and chemistry. These improvements suggest that constraints from space-based observations of the processes affecting urban photochemistry are possible at a level of detail not previously described. © 2014 Author.