Characteristics of 1961-2008 Haze Weather over Nanjing and Its Long-Range Variability

摘要

Statistical research is made into the variation in haze weather over the urban area of Nanjing using 1961-2008 daily observations by means of the methods of tread coefficient and correlation coefficient as well as the binomial running averaging technique, leading to the conclusions as follows. 1) the highest (lowest) frequency occurs in December (July), with the sum of haze days in autumn, winter and spring constituting＞85％of the annual total;2) the annual haze days has exhibited an increasing tread, on the whole,since the 1960s, with the variation of yearly haze days falling into 4 types, with the sharply ascending phases from the late 1970s to the mid 1990s and between the end of the 1990s and 2008.