摘要
In this paper, the microphysical relationships of 8 dense fog events collected from a comprehensive fog observation campaign carried out at Pancheng（32.2 N, 118.7 E） in the Nanjing area, China in the winter of 2007 are investigated. Positive correlations are found among key microphysical properties（cloud droplet number concentration, droplet size, spectral standard deviation, and liquid water content） in each case, suggesting that the dominant processes in these fog events are likely droplet nucleation with subsequent condensational growth and/or droplet deactivation via complete evaporation of some droplets. The abrupt broadening of the fog droplet spectra indicates the occurrence of the collision-coalescence processes as well, although not dominating. The combined efects of the dominant processes and collision-coalescence on microphysical relationships are further analyzed by dividing the dataset according to visibility or autoconversion threshold in each case. The result shows that the specific relationships of number concentration to volume-mean radius and spectral standard deviation depend on the competition between the compensation of small droplets due to nucleation-condensation and the loss of small droplets due to collision-coalescence. Generally, positive correlations are found for diferent visibility or autoconversion threshold ranges in most cases, although negative correlations sometimes appear with lower visibility or larger autoconversion threshold. Therefore, the compensation of small droplets is generally stronger than the loss, which is likely related to the sufcient fog condensation nuclei in this polluted area.
In this paper, the microphysical relationships of 8 dense fog events collected from a comprehensive fog observation campaign carried out at Pancheng（32.2 N, 118.7 E） in the Nanjing area, China in the winter of 2007 are investigated. Positive correlations are found among key microphysical properties（cloud droplet number concentration, droplet size, spectral standard deviation, and liquid water content） in each case, suggesting that the dominant processes in these fog events are likely droplet nucleation with subsequent condensational growth and/or droplet deactivation via complete evaporation of some droplets. The abrupt broadening of the fog droplet spectra indicates the occurrence of the collision-coalescence processes as well, although not dominating. The combined efects of the dominant processes and collision-coalescence on microphysical relationships are further analyzed by dividing the dataset according to visibility or autoconversion threshold in each case. The result shows that the specific relationships of number concentration to volume-mean radius and spectral standard deviation depend on the competition between the compensation of small droplets due to nucleation-condensation and the loss of small droplets due to collision-coalescence. Generally, positive correlations are found for diferent visibility or autoconversion threshold ranges in most cases, although negative correlations sometimes appear with lower visibility or larger autoconversion threshold. Therefore, the compensation of small droplets is generally stronger than the loss, which is likely related to the sufcient fog condensation nuclei in this polluted area.
基金
Supported by National Natural Science Foundation of China (41305120,41030962,41275151,41375138,41375137,and 41305034)
Natural Science Foundation of Jiangsu Province (BK20130988,SK201220841)
Specialized Research Fund for the Doctoral Program of Higher Education (20133228120002)
China Meteorological Administration Special Public Welfare Research Fund (GYHY201406007)
Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (13KJB170014)
Open Funding from Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration (KDW1201,KDW1102)
Open Funding from Key Laboratory of Meteorological Disaster of Ministry of Education (KLME1205,KLME1107)
Open Funding from State Key Laboratory of Severe Weather (2013LASW-B06)
Qing-Lan Project for Cloud-Fog-Precipitation-Aerosol Study in Jiangsu Province
Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
U.S. Department of Energy’s (DOE) Earth System Modeling (ESM) program via the FASTER project (www.bnl.gov/faster) and Atmospheric System Research (ASR) program
