Analysis of the Microphysical Structure of Heavy Fog Using a Droplet Spectrometer:A Case Study  

作　　者：牛生杰 陆春松 刘延刚 赵丽娟 吕晶晶 杨军 

机构地区：[1]Key Laboratory of Meteorological Disaster of Ministry of Education,School of Atmospheric Physics,Nanjing University of Information Science & Technology [2]Brookhaven National Laboratory,Atmospheric Sciences Division

出　　处：《Advances in Atmospheric Sciences》2010年第6期1259-1275,共17页大气科学进展（英文版）

基　　金：mainly provided by the National Natural Science Foundation of China (Grant Nos. 40537034 and 40775012);the Natural Science Fund for Universities in Jiangsu Province(Grant Nos. 06KJA17021 and 08KJA170002);the Meteorology Fund of the Ministry of Science and Technology [Grant No. GYHY (QX) 2007-6-26];the Qing-Lan Project for cloud-fog-precipitation-aerosol study in Jiangsu Province and the Graduate Student Innovation Plan in the Universities of Jiangsu Province (CX09B 226Z)

摘　　要：The microphysical properties of a long-lasting heavy fog event are examined based on the results from a comprehensive field campaign conducted during the winter of 2006 at Pancheng （32.2°N, 118.7°E）, Jiangsu Province, China. It is demonstrated that the key microphysical properties （liquid water content, fog droplet concentration, mean radius and standard deviation） exhibited positive correlations with one another in general, and that the 5-min-average maximum value of fog liquid water content was sometimes greater than 0.5 g m-3. Further analysis shows that the unique combination of positive correlations likely arose from the simultaneous supply of moist air and fog condensation nuclei associated with the advection of warm air, which further led to high liquid water content. High values of liquid water content and droplet concentration conspired to cause low visibility （〈50 m） for a prolonged period of about 40 h. Examination of the microphysical relationships conditioned by the corresponding autoconversion threshold functions shows that the collision-coalescence process was sometimes likely to occur, weakening the positive correlations induced by droplet activation and condensational growth. Statistical analysis shows that the observed droplet size distribution can be described well by the Gamma distribution.The microphysical properties of a long-lasting heavy fog event are examined based on the results from a comprehensive field campaign conducted during the winter of 2006 at Pancheng （32.2°N, 118.7°E）, Jiangsu Province, China. It is demonstrated that the key microphysical properties （liquid water content, fog droplet concentration, mean radius and standard deviation） exhibited positive correlations with one another in general, and that the 5-min-average maximum value of fog liquid water content was sometimes greater than 0.5 g m-3. Further analysis shows that the unique combination of positive correlations likely arose from the simultaneous supply of moist air and fog condensation nuclei associated with the advection of warm air, which further led to high liquid water content. High values of liquid water content and droplet concentration conspired to cause low visibility （〈50 m） for a prolonged period of about 40 h. Examination of the microphysical relationships conditioned by the corresponding autoconversion threshold functions shows that the collision-coalescence process was sometimes likely to occur, weakening the positive correlations induced by droplet activation and condensational growth. Statistical analysis shows that the observed droplet size distribution can be described well by the Gamma distribution.

关 键 词：fog microphysics positive correlation high liquid water content low visibility warm and moistair 

分 类 号：P426.4[天文地球—大气科学及气象学]