Beijing Olympics as an aerosol field experiment

During the 2008 Olympic Summer Games, emission reductions were enforced in Beijing to improve air quality. Here we explore their effect on the regional aerosol load. We compare satellite-retrieved aerosol optical thickness (AOT) of that period with previous years, both in absolute terms and in a neural network approach taking into account the meteorological conditions. A statistically significant reduction of aerosol load is found in Beijing that decreases in magnitude and significance with increasing region size. Locally, the aerosol load (log(AOT)) was about 0.4 to 0.75 standard deviations below the levels expected for the prevailing meteorological situation. The small size of this effect relative to meteorological variability highlights the importance of regional aerosol transport. Citation: Cermak, J., and R. Knutti (2009), Beijing Olympics as an aerosol field experiment, Geophys. Res. Lett., 36, L10806, doi: 10.1029/2009GL038572.