[Temporal and Spatial Variation of Haze Pollution over China from 1960 to 2013]

Based on haze observation and related meteorological data from the surface weather stations in China during 1960-2013, we analyzed the variation of haze days and its relationship to meteorological elements using climatic linear-trend estimation, cluster analysis, cumulative departure and the Mann-Kendall test. The results showed that the haze events occurred mainly in mid-eastern and southern China, especially in Beijing, central and southern areas of Shanxi, Henan, the Yangtze River Delta and Pearl River Delta areas. At the same time, the haze days were less frequently observed in western and northeastern China. The occurrence of haze days was increasing in the past 54 years, which was consistent with the total energy consumption in China. While the emission of air pollutant could be an important factor of haze increase, the adverse weather conditions also played a role. The correlation coefficients of precipitation, average wind speed, sunshine duration and relative humidity with haze days were -0.653, -0.635, -0.462 and -0.699, respectively, which all exceeded the 99.9% significance. Cluster analysis showed that haze days of stations with very significant increase, significant increase and obvious increase have accelerated in recent years, and the trend of cumulative variance type was fall-flat-rise. Haze days of slight rise station increased from 1960s to the late1970s and after 2000, of which cumulative variance type was multi wobbled. Moreover, Haze days of slight fall and obvious fall stations increased from 1960s to 1970s, and their cumulative variance types were rise-gently-fall. Furthermore, haze days showed mutation from more to less during 1992 to 1993.