华北地区云凝结核的观测研究  

OBSERVATIONS OF CLOUD CONDENSATION NUCLEI IN NORTH CHINA

作　　者：石立新[1] 段英[1] 

机构地区：[1]河北省人工影响天气办公室

出　　处：《气象学报》2007年第4期644-652,共9页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(40475003);河北省自然科学基金(D2005000593)

摘　　要：利用连续气流纵向热梯度云凝结核仪对中国华北地区空中和地面的云凝结核(CCN)进行了观测研究。2005年秋季和2006年春季的飞机观测结果表明,华北地区的CCN主要来源于地面,近地层CCN浓度较高,CCN浓度随高度增加而减少;CCN的分布与地面源地密切相关,污染地区乡村上空CCN浓度比无污染地区乡村高5倍以上,而污染城市上空的CCN浓度无显著差异;水平穿越淡积云云簇时云内CCN明显减少,表明云对CCN的消耗作用。2005年夏季石家庄地面CCN观测显示,同一过饱和度(S)下的CCN浓度差异很大,在S=0.1%、0.3%和0.5%下的最小值分别为584、808和2431个/cm3,最大值分别为9495、16332和21812个/cm3;CCN有明显的日变化,06时以后浓度开始上升,上午至中午前后达到极大值,下午浓度下降,原因可能是由于上午汽车排放以及光化学产物开始增加所致;降水对CCN具有冲刷作用。本文根据关系式N=CSk拟合得到的空中和地面的CCN活化谱参数C值明显较大(大于1000),k值较高(约0.7),表明华北地区CCN具有大陆性特征。Using a DMT （Droplet Measurement Technologies） continuous flow streamwise thermal gradient cloud condensation nuclei （CCN） counter mounted on a Cheyenne Ⅲ A aircraft, aircraft measurements of CCN in about 20 flights over North China were conducted in the autumn of 2005 and spring of 2006. According to the design for aircraft observation, the method of spiral ascent and descent in the troposphere was used in the vertical measurement of CCN, and some certain levels were chosen for horizontal measurement. The vertical distributions of CCN concentrations show that CCN particles most concentrated in the low level of the troposphere and the CCN concentration decreased with height, suggesting that the main source of CCN is from ground surface. This result is consistent with previous studies in 1983 - 1985 in China where a static thermal gradient CCN counter were employed. The comparison of vertical observations between polluted rural areas near Shijiazhuang and non-polluted rural areas in Zhangjiakou shows that the former＇ s CCN concentration was about five times the latter＇s, but over two polluted cities, Shijiazhuang and Handan, there wasn＇t notable difference. The horizontal measurements from experiments penetrating the cumulus clouds shows the apparent decrease of CCN in clouds, confirming that cloud has a definite depletion effect on CCN particles due to the scavenging of cloud droplets. The surface measurements of CCN in Shijiazhuang City were made from June to August in 2005. The statistical results of CCN measurments show the great difference in concentration at the same supersaturation （S） in Shijiazhuang summertime. The minimum concentrations were 584 cm^-3, 808 cm^-3 and 2431 cm^-3, and the maximum concentrations 9495 cm^-3, 16332 cm^-3 and 21812 cm^-3 at S = 0.1%, 0.3 % , and 0.5 % respectively. The CCN had a distinctive diurnal cycle, i.e. it began to increase from 06：00 BST, and reached the maximum till about noon, then generally decreased throughout the afternoon. The reason might be

关 键 词：华北 云凝结核 观测 

分 类 号：P185.82[天文地球—天文学]