Model derived tropospheric NO2 columns compared with GOME measurements

Abstract

Tropospheric NO2 columns derived from measurements by the GOME satellite instrument have been compared with calculations from the global chemistry-transport model MOZART, in order to gain insights into the distribution and fate of atmospheric NO2. The measured and modelled NO2 columns show similar spatial and seasonal patterns, with large tropospheric column amounts over industrialized areas and small column amounts over remote areas. The comparison of the absolute values of the measured and modelled tropospheric columns are particularly dependent upon uncertainties in the derivation of the tropospheric NO2 columns from GOME and the difficulty of modelling the boundary layer in global models. The measured tropospheric column amounts derived from GOME data are of the same order as those calculated by MOZART over the industrialized areas of the USA and Europe, but a factor of 2-3 larger for Asia. The modelled tropospheric NO2 columns as well as the columns measured by GOME are in good agreement with NO2 columns derived from observed NO2 mixing ratios in the boundary layer in eastern North America. In the near future it is expected that the GOME NO2 columns can be used to identify 'hot spots' of regional air pollution on a global map, useful for assessment studies.