中文摘要：

通过2004年10月在珠江三角洲(以下简称“珠三角”)开展大气边界层观测试验得到的垂直风温资料和逐时PM2.5浓度资料,利用局地环流指数(RF)等方法研究了珠三角海陆风特征及其对空气质量的影响.结果表明:局地环流指数是表征局地大气输送能力的有效指标;冷暖气团对峙导致珠三角污染日背景风场较弱,沿海海陆风活动活跃,空气质量指数与RF系数相关性颇高,珠三角沿海100~400m处RF系数值主要分布在0.5~0.8之间;在海陆风影响下低层风场的有效输送能力较弱,不利于污染物的输送扩散.而随着冷空气全面控制珠三角,垂直风场RF系数值高达0.9以上,海陆风难以发展,风场输送能力强,能够持续的将污染物输送出去.观测发现沿海观测点试验期间海陆风发生频率约为47.8%,其中72.7%的海陆风日出现了污染天气,海陆风日地面风向呈现出明显的随时间顺时针偏转特征,海风约从16:00时开始出现,并在20:00达到最大影响高度约为600~800m.夜间海风将污染物输送回内陆观测点,导致内陆PM2.5浓度在19:00~21:00时出现浓度峰值,呈现出明显的双峰结构.

英文摘要：

Based on the sounding data obtained from the boundary layer observation experiment over Pearl River Delta(PRD) region during October 2004 and the corresponding hourly PM2.5 data, the characteristics of sea-land breezes and itsinfluenceson quality over PRD region were discussed by Recirculation Factor (RF) and other methods. Recirculationfactor was a useful tool to represent the atmospheric horizontal transmission capacity.With the influence of the cold airand warm air confront with each other during pollution days, the sea-land breezes occurred frequently as a result of theweak system wind, and air quality index had significant relation with the RF, the RF of 100~400m was about 0.5~0.8. Thehorizontal transmission capacity of vertical wind field was weak under the influence of sea-land breezes, not conducive tothe spread of pollutants. As PRD controlled by cold air overall, the RF of vertical windreach up to 0.9, and sea-landbreezes circulation was hard to developing,so the horizontal transmissions capacity was powerful and the pollutants couldbe spread effectually. Among the observations, the frequency of sea-land breezes was about 47.8% at the coastal station,and the 72.7% of sea-land breezes day was pollution day, the wind directionhad visible change in clockwise over time.The sea breeze occurred in 16:00, and reached the maximum in 20:00 with the influence height was about 600~800m. Inthe night, sea breeze may transport the pollutants back to inland, and gave rise to a peak value of PM2.5 concentrationappeared at 19:00 to 21:00 in inland station.