台风过程珠江三角洲边界层特征及其对空气质量的影响

利用2006年7月珠江三角洲南北向3个点为期1个月的小球测风、低空探空资料及9个地面气象站逐时风向、风速资料,通过计算和分析风、温梯度资料,研究了台风过程珠江三角洲边界层特征及其对珠江三角洲地区空气质量的影响,重点分析了台风下沉气流影响导致灰霾天气期间的边界层结构.结果表明,2006年7月珠江三角洲地区空气质量主要受2个台风过程影响,当台风中心位于粤东及福建以东海域时,台风外围的下沉气流会对珠江三角洲地区的空气质量产生强烈影响,出现灰霾天气.在台风登陆前出现灰霾日时,珠江三角洲被均压场所控制,大部分区域为静小风,沿海地区会出现局地的海陆风,边界层风速较小.在200~500m低空会出现逆温层,同时最大混合层高度迅速下降到不足500m.

The characteristics of atmospheric boundary layer during tropical cyclone process and its influence on air quality over Pearl River Delta region

Based on the sounding data at 3 stations from the boundary layer observation experiment over Pearl River Delta (PRD) region during July 2006 and the corresponding hourly wind data from other 9 meteorological stations, the influences of tropical cyclone process on air quality over PRD region were discussed by analyzing the gradient and fluctuation of wind and temperature measured in the observation experiment, and the variation characteristics of atmospheric boundary layer in haze weather which affected by tropical cyclone process were also analyzed. It was found that, the air quality was strong influenced by the tropical cyclone when typhoon center was near coastland of East Guangdong and Fujian provinces. During the haze weather which impacted by peripheral subsidence flow of tropical cyclone process, the PRD region was under the control of uniform pressure field, and the wind was light in most parts of PRD, the wind speed was small in boundary layer and sea-land breeze had significant influence on air quality. Before tropical cyclone landing, temperature inversion layer occurred in 200~500m, the maximum mixing layer height decreased to lower than 500m dramatically.