华南准静止锋暖区内降水的物理化学特征

Physical and Chemical Characteristics of Precipitation within the Warm Sector of a Quasi-stationary Front in South China

介绍了一次华南准静止锋暖区内降水的物理化学特征的综合观测分析结果。主要有：①暖区内积云降水雨滴浓度不高，但滴径较大，谱型以多峰谱为主；②雨水ｐＨ值较低，平均４．４３，离子成分中ＮＯ，Ｃｌ，ＳＯ，ＮＨ，Ｎａ＋的浓度较高；③本次降水清除了气溶胶总质量的４５％，对Ｃｌ－，Ｆ－，ＮＯ的清除率较高；④由于气溶胶中阴离子被雨水清除的效率较高（主要是ＮＯ）而阳离子的清除率低，致使雨水ｐＨ值下降，这可能是本次降水雨水酸度较大的原因之一。

The results are presented of a comprehensive observational analysis of physical and chemical characteristics of precipitation within the warm sector of a quasi-stationary front in South China.It is found that(1) inside the warm sector the mild raindrop concentration in the cumulus rainfall is associated with reasonably large drop diameter, with spectral pattern dominated by multiple peaks; (2) the pH value of the rainwater is low,averagihg at 4. 43,and NO,Cl-,SO,NH and Na+ are highly concentrated among the compositions of ions; (3) the scavenging rate for this rainfall is 45 % of the total mass of aerosols,especially higher for Cl-,F- and NO;(4) because the scavenging rate is large for the anion (mainly NO) and small for the cation in the aerosols,the pH value is decreased,becoming one of the causes for the relatively higher acidity in the rainwater in this process of precipitation.