太原市酸雨变化特征及影响因素分析

为了能够掌握太原市酸雨的发生规律，进而为开展环境气象预报及酸雨污染防治提供科学依据，笔者利用太原市2001—2012年的酸雨观测资料和地面常规观测资料，采用统计分析的方法分析了太原市酸雨的变化特征及影响因素。结果表明：12年间，太原市的年平均降水pH值全部大于4.5，均为弱酸雨或非酸雨程度，且总体上呈现逐年上升的趋势；太原市酸雨的发生频率和强度呈较明显的季节性变化，表现为夏秋两季酸雨较重、春冬季节酸雨较轻。另外，气象条件也是影响降水酸度的主要因素：日降水量达大雨量级时的酸雨频率最高；风速小于0.2 m/s时，酸雨出现频率最高；低层出现逆温也易造成酸雨。

Variation Characteristics and Affecting Factors Analysis of Acid Rain in Taiyuan

In order to grasp the occurrence law of acid rain in Taiyuan, and then provide a scientific basis for carrying out environmental weather forecasts and acid rain prevention, the observational datum from 2001 to 2012 were used to statistically analyze the variation characteristics and affecting factors of acid rain in Taiyuan. The results showed that: the annual average precipitation pH value of 12 years was above 4.5, which indicated that weak acid rain/non-acid rain occurred, and was likely to rise year by year. There were obvious seasonal variation patterns in both the frequency and acidity of acid rain, which revealed that the acid rain pollutions were more severe in summer and autumn, while lighter in spring and winter. In addition, the climatic conditions had main effect on the acidity of precipitation. For example, the acid rain frequency reached the peak when the daily precipitation accumulated to heavy rain level or the speed of ground wind was lower than 0.2 m/s; besides, the inverse temperature under low level facilitated the occurrence of acid rain.