Aircraft measurements of the vertical distribution of sulfur dioxide and aerosol scattering coefficient in China

Information on the vertical distribution of air pollution is important for understanding its sources and processes and validating satellite retrievals and chemical transport models. This paper reports the results of the measurements of sulfur dioxide (SO2) and aerosol scattering coefficient (Bsp) obtained from several aircraft campaigns during summer and autumn 2007 in the north-eastern (NE), north-western (NW), and central-eastern (CE) regions of China. Their vertical profiles over the three regions with contrasting emission characteristics and climates are compared. Very high concentrations/values of SO2 and Bsp (with a value of up to 51 ppbv and 950 Mm−1, respectively) were recorded in the lower planetary boundary layer in CE China, indicating high SO2 emissions in the region. The SO2 column concentrations determined from the in-situ measurements were compared with Ozone Monitoring Instrument (OMI) SO2 retrievals. The results show that the OMI data could distinguish the varying levels of SO2 pollution in the study regions, but appeared to have underestimated the SO2 column in the highly polluted region of CE China.