Satellite and In Situ Measurement of NO2

A novel method was developed for producing high-resolution (∼ 11km) maps of surface NO2 concentrations by combining satellite retrieved NO2 columns from OMI with in situ measurements made by permanent monitoring networks. Field data from the BAQS-met field campaign in the Windsor area during 2007 was used to validate this method and explore the uncertainties and biases in the inferred values. Good correlation with the network of passive monitors was found (R = 0.69). Interference of NOz in traditional NO2 measurements was found to be small (0.9 ppb) when considered for 24-hr averages. The inference method was extended to qualitatively analyze long-term trends in Windsor. Comparison against a land-use regression model in Toronto showed similar overall trends, but the downtown core was underestimated considerably by the OMI-inferred map. While the presented inference method can simplify and increase the utility of OMI NO2 data, limitations remain as to the spatial and temporal resolution achievable.MAS