Trends of Tropospheric Ozone over China Based on Satellite Data (1979-2005)

Long-term trends of yearly and seasonal averages of tropospheric ozone over the whole country and some important regions of China during 1979-2005 are analyzed, based on tropospheric ozone residue (TOR) data retrieved from satellite measurements. The relationship between the TOR and Southern Oscillation Index (SOI) is studied. The results show that, over the whole country, there is a slight increase of TOR in summer and a decrease in other seasons, while the overall trend for the whole period is insignificant. There are decreasing trends of TOR over the Pearl River Delta and the Sichuan Basin. Significant increasing trends of TOR are found over the North China Plain (NCP) for all seasons except for winter, with a maximum rate of 1.10 DU per decade for summer. There are significant correlations between TOR and SOI for some regions in China but not for the NCP, suggesting that the observed increasing trend of TOR over the NCP may not be linked with changes in atmospheric circulations.