Satellite observations of Mexico City pollution outflow from the Tropospheric Emissions Spectrometer (TES)

Concurrent tropospheric O-3 and CO vertical profiles from the Tropospheric Emission Spectrometer (TES) during the MILAGRO/INTEX-B aircraft campaigns over the Mexico City Metropolitan Area (MCMA) and its surrounding regions were used to examine Mexico City pollution outflow on a regional scale. The pollution outflow from the MCMA occurred predominantly at 600-800 hPa as evident in O-3, CO, and NOx enhancements in the in situ aircraft observations. TES O-3 and CO are sensitive to the MCMA pollution outflow due to their relatively high sensitivities at 600-800 hPa. We examined O-3, CO, and their correlation at 600-800 hPa from TES retrievals, aircraft measurements, and GEOS-Chem model results. TES captures much of the spatial and day-to-day variability of O-3 seen in the in situ data. TES CO, however, shows much less spatial and day-to-day variability compared with the in situ observations. The Delta O-3/Delta CO slope is significantly higher in the TES data (0.43) than the in situ data (0.28) due partly to the lack of variability in TES CO. Extraordinarily high Delta O-3/Delta CO slope (0.81) from TES observations at 618 hPa over the Eastern U.S. was previously reported by Zhang et al. [Zhang, L.. Jacob, D.J., Bowman, K.W., et al.. 2006. Ozone-CO correlations determined by the TES satellite instrument in continental outflow regions. Geophys. Res. Lett. 33, L18804.10.1029/2006GL026399.]. Thus the application of TES CO-O-3 correlation to map continental pollution outflow needs further examination. Published by Elsevier Ltd.