Spatiotemporal variations of tropospheric SO2 over China by SCIAMACHY observations during 2004-2009

► We validate SCIAMACHY SO2 data by MAXDOAS in China. ► Different seasonal variation is found for different energy demand. ► Tropospheric SO2 was partly under control from 2007 for the reduction policy. ► SO2 decrease in several cities for pollution control for the 2008 Olympic Games.