Temporal-spatial variations of tropospheric SO2 over China using SCIAMACHY satellite observations

The data products of monthly average troposphric SO₂ vertical column densities over China from January 2004 to November 2009 are acquired from the SCIAMACHY instrument on board ENVISAT. The results of monthly average tropospheric SO₂ vertical column densities were analyzed to research the temporal-spatial distribution and change trends of tropospheric SO₂ over China. In this paper, we selected four typical SO₂ high concentration regions and described the spatial distribution, interannual change and seasonal variation, and the changes before and after the Beijing Olympic Games in these four regions. Additional, we analyzed the possible reasons for those change trends. The results showed that human activities play a key role in the distribution and variation of tropospheric SO₂. The North China region is provided with the highest concentration of SO₂ mainly because it´s the major area of coal producing and consuming. Tropospheric SO₂ concentration declined in North China in 2008 while it dropped in South China since 2007. The seasonal variation of the SO₂ column densities exhibits a structure with peak in winter and spring on account of central heating and lowest in summer in North China, yet it appears oppositely in the Pearl River Delta area. And the temporal-spatial change trends are remarkably affected by sulfur control policies. We found that the tropospheric SO₂ column densities decreased strongly during and after the Beijing Olympic Games opened in August 2008. The tropospheric SO₂ column densities in August 2008 dropped by 50% compared to SO₂ concentration in August 2007. Furthermore our study finally confirms that remote sensing has a high application value in measuring trace gases and monitoring air pollution on a larger scale compared to traditional methods.