The Study on the Space-time Distribution Characteristics of Acid Rain in Southwest

Based on the observational data more than 10 years from 1993 to 2004,which were collected from a total of 17 observation stations under the acid rain observation network in southwest belongs to the China Meteorological Administration,including Sichuan,Chongqing,Guizhou,Kunming and Tibet,total five provinces,municipalities and autonomous regions,we make a study about the pH value of precipitation,frequency of acid rain,temporal and spatial distribution characteristics of precipitation conductivity in the southwestern region.The results show that little acid rain in Hongyuan,Lhasa and Ganzi,the highest frequency of acid rain in Chongqing;minimum mean pH of precipitation but more acidic in Zunyi;acid rain has reduced in inter-annual variability trends;acid rain intensity and frequency has significant monthly changes feature,and with a positive correlation between precipitation,the change-curve is similar with the U-distribution.The acid rain pollution is still serious in the southwestern region.