Spatiotemporal Characteristics of Haze Days under Heavy Pollution over Central and Eastern China during 1960-2010

The spatiotemporal characteristics of haze days over central and eastern China have been analyzed. The results show that the major haze values are distributed in the Sichuan Basin, the Beijing-Tianjin-Hebei area, the middle and lower reaches of the Yangtze River, and the central regions of Guangdong and Guangxi. The days with the heaviest and lightest amounts of haze occurred in winter and summer, respectively. The values of the haze days in the central and southwestern Beijing-Tianjin-Hebei megacity area, the Sichuan Basin, and the eastern and southern regions of Northeast China exceeded 20 d. In addition, the maximum climate trend coefficient of the Beijing-Tianjin-Hebei area and the Yangtze and Pearl river deltas was 0.8. The annual average haze days showed an obvious upward trend of 3.69 d (10 a)^-1 and a climate trend coefficient of 0.82, which passes 99.9% statistical significance. Moreover, the spatial distributions of aerosol optical depth (AOD) and tropospheric column NO₂ (TroNO₂) were consistent with the annual average haze days over eastern China, and the energy consumption in China showed a stable upward trend during 1960-2010. These results indicate that the increase in air pollution disposal is a main contributing factor in the increase of haze days.