降水时空变化对中国南方强酸雨分布的影响

利用SCIAMACHY、GOME卫星资料反演的SO2、NO2柱浓度和中国重点城市S02排放量数据分析了中国酸雨前体物时空分布特征．并结合气象观测资料探讨了在降水分布出现气候学时空尺度调整的背景下，降水长期变化对强酸雨分布的影响。结果表明：（1）中国南方地区NO2、SO2排放量相对于降水的冲刷能力而言仍然处于较高的水平，为强酸雨的形成提供了充足的污染物条件。（2）1993-2004年间，以1999年为转折期，中国南方强酸雨分布形势经历了一个由强到弱到再次增强的过程。1999年后．西南强酸雨区强酸雨城市比例持续下降，江南强酸雨区强酸雨城市比例迅速增加，强酸雨东移扩大趋势明显。（3）中国南方强酸雨区的空间分布与1961-2006年冬夏季降水量线性增减速率超过10mm／10a的地区一致。以季节降水量线性增减速率超过10mm／10a为界．将江南及西南强酸雨区各季节降水量做线性趋势和突变分析．发现江南地区冬夏季降水量在1999年出现增减趋势转换．与强酸雨城市比例转折的时间一致。其中，1991-1999年江南强酸雨区冬季降水减少．夏季暴雨显著增加，有利于酸雨缓解，强酸雨范围缩小；而2000-2006年，冬季降水处于偏多时期，夏季降水却相对偏少，强酸雨覆盖范围扩大。西南强酸雨区春秋季降水量在1990年后持续减少．导致春秋季降水占年降水量比例下降．使得年降水pH值升高．强酸雨形势得到缓解。

Impact of Spatio- temporal Variation of Precipitation on Severe Acid Rain in Southern China

In this paper,we present the effects of regional precipitation trend change on the frequency,area and intensity of severe acid rain over southern China,where the significant abrupt change in seasonal precipitation has occurred since the 1990s,and based on SO2 and NO2 slant column data retrieved from both SCIAMACHY and GOME,the spatio-temporal distribution characteristics of SO2 and NO2 density are analyzed,too.The results indicate:(1) The emission levels of SO2 and NO2 have reached or passed precipitation scavenging capacity in parts of southern China due to SO2 and NOx total emission amount durative increasing from 1993 to 2004,especially in the region south of the middle and lower Yangtze River.(2) The changes of the severe acid rain city proportion mainly occurred in the region with severe acid rain south of the Yangtze River during 1993 to 2004.With the occurrence of abrupt change in 1999,the severe acid rain mainly moved westwards from 1993 to 1999,and moved eastwards due to the proportion increased in the region with severe acid rain south of the Yangtze River during 2000 to 2004.(3) It is found that the spatial distribution and variation of seasonal precipitation change rate over 10 mm/10a are in a good agreement with those of severe acid over southern China.There occurred a same abrupt period in 1999 for the variation of severe acid rain city proportion and the variation of seasonal precipitation in winter and summer over southern severe acid rain.