The Influence of Freezing Drizzle on Wire Icing during Freezing Fog Events  

作　　者：周悦 牛生杰 吕晶晶 

机构地区：[1]Jiangsu Key Laboratory of Atmospheric Environmental Monitoring and Pollution Control, School of Atmospheric Physics, Nanjing University of Information Science and Technology [2]Hubei Key Laboratory for Heavy Rain Monitoring and Warning Research, Institute of Heavy Rain, China Meteorological Administration

出　　处：《Advances in Atmospheric Sciences》2013年第4期1053-1069,共17页大气科学进展（英文版）

基　　金：supported by the National Key Technology R&D Program (Grant No. 2008BAC48B01);the National Natural Science Foundation of China (Grant Nos. 40775012 and 41275151);the Jiangsu Province Qinglan Project for Cloud Fog Precipitation;the Aerosol Research Group, a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions;the Graduate Student Innovation Plan in the Universities of Jiangsu Province

摘　　要：Both direct and indirect effects of freezing drizzle on ice accretion were analyzed for ten freezing drizzle events during a comprehensive ice thickness, fog, and precipitation observation campaign carried out during the winter of 2008 and 2009 at Enshi Radar Station （30°17′N, 109°16′E）, Hubei Province, China. The growth rate of ice thickness was 0.85 mm h-1 during the freezing drizzle period, while the rate was only 0：4 mm h-1 without sleet and freezing drizzle. The rain intensity, liquid water content （LWC）, and diameter of freezing drizzle stayed at low values. The development of microphysical properties of fog was suppressed in the freezing drizzle period. A threshold diameter （Dc） was proposed to estimate the influence of freezing drizzle on different size ranges of fog droplets. Fog droplets with a diameter less than Dc would be affected slightly by freezing drizzle, while larger fog droplets would be affected significantly. Dc had a correlation with the average rain intensity, with a correlation coefficient of 0.78. The relationships among the microphysical properties of fog droplets were all positive when the effect of freezing drizzle was weak, while they became poor positive correlations, or even negative correlations during freezing drizzle period. The direct contribution of freezing drizzle to ice thickness was about 14.5%. Considering both the direct and indirect effects, we suggest that freezing drizzle could act as a ＂catalyst＂ causing serious icing conditions.Both direct and indirect effects of freezing drizzle on ice accretion were analyzed for ten freezing drizzle events during a comprehensive ice thickness, fog, and precipitation observation campaign carried out during the winter of 2008 and 2009 at Enshi Radar Station （30°17′N, 109°16′E）, Hubei Province, China. The growth rate of ice thickness was 0.85 mm h-1 during the freezing drizzle period, while the rate was only 0：4 mm h-1 without sleet and freezing drizzle. The rain intensity, liquid water content （LWC）, and diameter of freezing drizzle stayed at low values. The development of microphysical properties of fog was suppressed in the freezing drizzle period. A threshold diameter （Dc） was proposed to estimate the influence of freezing drizzle on different size ranges of fog droplets. Fog droplets with a diameter less than Dc would be affected slightly by freezing drizzle, while larger fog droplets would be affected significantly. Dc had a correlation with the average rain intensity, with a correlation coefficient of 0.78. The relationships among the microphysical properties of fog droplets were all positive when the effect of freezing drizzle was weak, while they became poor positive correlations, or even negative correlations during freezing drizzle period. The direct contribution of freezing drizzle to ice thickness was about 14.5%. Considering both the direct and indirect effects, we suggest that freezing drizzle could act as a ＂catalyst＂ causing serious icing conditions.

关 键 词：freezing drizzle freezing fog ice accretion microphysical property promoting factor 

分 类 号：P426.63[天文地球—大气科学及气象学]