SpatioTemporal Characteristics of Haze and Its Forming Reason in Jiangxi Province During the Past 50 Years
The spatio-temporal distribution characteristics of haze and the climatic background were analyzed by using the daily haze abservations from 83 meteorological stations from 1964 to 2013 and the statistical method of linear regression.The results showed that haze days are significantly more in central and northern Jiangxi than in southern Jiangxi. The annual haze days more than 30 d appear in central Jiangxi, including Pingxiang, Yichun, Fuzhou and Shangrao, and also in northern Jiangxi, including central Jiujiang and northern Jingdezhen. The haze days are maximum in winter, followed by autumn and spring, and the minimum in summer. The central and northern parts of Pingxiang, Yichun and Yingtan and the central part of Nanchang and Jiujiang as well as the eastern part of Shangrao have more than 20 haze days per year. The haze days are the most in December, 〖JP2〗nearly 20% of annual haze days. The haze days in Jiangxi〖JP〗 Province present a significant increasing trend with the increase rate 11 d per decade from 1964 to 2013 and the climatic trend coefficient is 0.78, which has passed the significance test at 0.01 level. The correlation coefficient between the haze days and the mean wind speed and strong wind days is negative, but is positive between haze days and calm days in Jiangxi. In the past 50 years, the annual averaged wind days and stong wind days show a downward trend, while the calm days show an upward trend, which may cause the accumulation of pollutants in the air to form more haze weather. The correlation coefficient between haze days and precipitation days is mainly negative and the precipitation days show a decreasing trend in Jiangxi，with the rate of around -6.3 d·（10 a）-1. The correlation coefficient between 〖JP2〗haze days and temperature is positive and the temperature shows an increasing trend in Jiangxi， with the rate of around 0.15℃·（10 a）-1.