哈尔滨市降水形势对大气污染物浓度稀释的影响

大量的观测事实和分析表明，随着季节的变化，降水对大气污染物浓度稀释的影响是比较复杂的。冬季，降雪越多，严重污染出现的概率越大；降雪时的天气往往风速小，湿度大，空气层结较稳定，扩散能力较弱。春季，降水对污染物浓度的影响就大一些，降水对PM10有较大的稀释作用，尤其对NO2稀释的影响更大一些，高湿的低温东风雨水对污染物浓度有降低的作用。夏季，降水大于等于10．0mm时高温高湿降水对污染物的稀释作用较大。秋季，高湿气压降低，降水10mm以下，对污染物浓度有降低的作用。

Influence of precipitation condition on dilution of atmospheric pollutant concentration in Harbin City

Large amount of observation and analysis shows that influence of precipitation on dilution of atmospheric pollutant concentration is more complicated, because of seasonal variation. In winter, the more the snowfall, the large the probability of pollution. At snowing time, the weather is often so that the wind speed is small, the air moisture is large, the air stratum is more stable and its diffusion capability is weak. In spring, the influence of precipitation on pollutant concentration and on dilution of PM10 and NO2 is obvious. The weather of high moisture and the rainwater with lower temperature plays a part in decreasing pollutant concentration. In summer, when the precipitation is equal to or larger than 10 mm, the weather with high temperature and moisture has an obvious effect on dilution of pollutant concentration. In Autumn, the decrease of air pressure with high moisture and the precipitation below 10 mm perform a function to reduce the pollutant concentration.