June 2007: Traffic Restrictions Associated with the Sino-African Summit: Reductions of NOx Detected from Space
Aggressive measures were instituted by the Beijing municipal authorities to restrict vehicular traffic in the Chinese capital during the recent Sino-African Summit (November 4-6, 2006). We show that reductions in associated emissions of NOx were detected by the Dutch-Finnish Ozone Monitoring Instrument (OMI) aboard the Aura satellite (figure below). Interpretation of these data using a 3-dimensional chemical transport model indicates that emissions of NOx were reduced by 40% over the period of November 4 to 6, 2006 for which the restrictions were in place.
The figure shows tropospheric vertical columns of NO2 over Beijing between October 25 and November 19, 2006. Mean OMI columns with standard deviations are shown for two horizontal scales surrounding Beijing: 0.5o (lat) x 0.5o (long) (solid red) and 2o x 2.5o (dashed red). NO2 columns simulated by the GEOS-Chem model using 2004 emissions are shown in black. A full description of this work is given in Wang et al. [2007] .