Measurement report: Spatiotemporal variability of peroxy acyl nitrates (PANs) over Mexico City from TES and CrIS satellite measurements

Abstract. Peroxy acyl nitrates (PANs) are photochemical pollutants with implications for health and atmospheric oxidation capacity. PANs formed via the of non-methane volatile organic compounds (NMVOCs) in presence nitrogen oxide radicals (NOx = NO + NO2). While urban environments large sources PANs, situ observations areas limited. Here we use satellite measurements from Tropospheric Emission Spectrometer (TES) Suomi National Polar-orbiting Partnership (S-NPP) Cross-track Infrared Sounder (CrIS) to evaluate spatiotemporal variability over around Mexico City. Monthly mean maxima City Metropolitan Area (MCMA) occur during spring months (March–May). This time year coincides a peak local photochemistry more frequent air stagnation. Local fire activity also typically peaks between February May, which leads strong interannual MCMA. We S-NPP CrIS data probe spatial outflow pattern produced within month largest mixing ratios (April). Peak April occurs northeast city mountains south city. Outflow northwest appears infrequently. Using 2018 versus 2019, show that were not significantly reduced year, significant decrease NOx Our analysis demonstrates space-based provided by TES can increase understanding surrounding