上海市大气降尘污染的地面气象背景特征

Surface Meteorological Characteristics of Atmospheric Dust Deposition Pollution in Shanghai

对上海市11 a(1993—2003年)的月降尘量和同期气象要素资料分析表明,降尘量的年际变化呈下降趋势、月际变化呈双峰型分布,气象因子是这种分布的主要影响因素;重点运用聚类分析方法将降尘地面气象背景分为A、B、C、D、E 5个类型,不同天气类型对降尘量的影响不同,其中A型最有利于降尘,其气象特征是偏南风频率、3 m/s以上风速频率、蒸发量和气温位居其他各类之首,降水量、雨日数、湿度中等,气压低。冬季,降水与降尘量呈现为一定的正相关关系。

This paper analyzes the characteristics and primary reasons of interannual and monthly variations of dust deposition in Shanghai on the basis of monthly dustfall and meteorological factors from 1993 to 2003. The interannual variations of dustfall showed a declining trend while monthly variations displayed a bimodal distribution. Synoptic backgrounds of dust deposition were classified into A, B, C, D and E types with different dustfalls by the method of clustering. Type A has the highest amount of dusffall. The closest related meteorological factors of Type A are orderly the frequencies of southerly winds and wind speed greater than 3 m/s, evaporation, and temperature;the next is precipitation, rain-days and moderate humidity;and the last is air pressure. In winter, positive correlation relationship between precipitation and dustfall is evident.