Long-term characteristics of satellite-based PM_2.5 over East China

With the explosive economic development of China over the past few decades, air pollution has become a serious environmental problem and has attracted increasing global concern. Using satellite-based PM_2.5 data from 2000 to 2015, we found that the temporal-spatial variation of PM_2.5 in East China is characterized by high concentrations in the northern part and low concentrations in the southern part of East China, and by being seasonally high in autumn and winter but low in spring and summer. We also found that the regional average PM_2.5 concentration shows an approximative peak pattern over the last 16years, with the highest, 60.13μgm^-3, and the lowest, 46.18μgm^-3, occurring in 2007 and 2000, respectively. Despite obviously diminishing heavy polluted regions with a PM_2.5 of >80μgm^-3 after 2011, those cells dominated by natural background have still not recovered back to the clean level of 2000. These characteristics are valuable information to analyze the relative contributions of anthropogenic emissions and atmospheric conditions to the temporal-spatial variation characteristics of PM_2.5.