Analysis Of Characteristics Of Precipitating Ice Clouds In Beijing-Tianjin-Hebei Region And Comparison With Non-precipitating Ice Clouds Based On MODIS And CloudSat

The data set in this paper is consist of a merged precipitation product developed by Nation Meterological Information Center,Aqua MODIS level 2 cloud product,CloudSat level 2 product,and MODIS L1 B radiance data.This paper mainly studies the properties of precipitating ice clouds and non-precipitating ice clouds in the Beijing-Tianjin-Hebei region,including macrophysical and microphysical properties of ice clouds during a heavy rainfall in summer,the comparative analysis of precipitating ice clouds and non-precipitating ice clouds,and seasonal distribution characteristics of precipitating ice clouds.The results reported here shows that:During a heavy rainfall,the ice clouds are mainly located above 3.5km.In the horizontal distribution,the cloud optical thickness,ice water path,cloud top height of ice clouds and precipitation intensity are positively correlated;in the vertical distribution,above 9 km,particles effective radius of ice clouds and precipitation are correlated;above 12 km,particles number concentration of ice clouds and precipitation are correlated;above 8.5 km,the ice water content of ice clouds and precipitation are correlated.The main type of ice cloud during a heavy rainfall is deep convective clouds.The highest particle number concentration of ice clouds is located in the upper layer of the cloud,and increases with height.The highest ice water content of ice clouds is located in the middle of the cloud.The particles effective radius,particle number concentration,and ice water content of ice clouds above 9 km are positively correlated with precipitation intensity.Precipitating ice clouds are dominated by deep convective clouds and nimbostratus,but non-precipitating ice clouds are dominated by altocumulus and cirrus clouds.Precipitating ice clouds mainly consist of single-layer clouds(80.39%),but double-layer clouds still account for a large proportion(18.75%)and are higher than non-precipitating ice clouds;non-precipitation ice clouds still consist of single-layer clouds(85.35%)and double-layer clouds(14.38%).Compared with non-precipitating ice clouds,the position of cirrus and altocumulus in precipitating ice clouds is higher,while the position of altostratus and deep convective are lower.The ice water content of non-precipitating ice clouds varies with height as a double peak structure,while that of precipitating ice cloud is a single peak structure;the particle number concentration of precipitating and non-precipitating ice clouds varies little with height;the particle effective radius of non-precipitating ice clouds varies little with height from 5 to 7.5 km,while precipitating ice clouds decrease with height.The ratio of the cloud water path,optical thickness and particle effective radius of the precipitating ice clouds b16>b21?b37 mode(b16,b21,b37 respectively represent the values of the cloud parameters in 1.6,2.1,3.7?m)are higher than non-precipitating ice clouds,and the ratio of the two parameters in the cloud parameter b21?b16?b37 mode is different.Occurrence probability of precipitating ice clouds in the total area of Beijing-Tianjin-Hebei region is high in summer,and the cloud top height of precipitating ice clouds in the total area of Beijing-Tianjin-Hebei is the highest in summer and the lowest in winter,while the minimum cloud top temperature of precipitating ice clouds in the same area is the lowest in summer and the highest in winter.The precipitating ice clouds in the total area of Beijing-Tianjin-Hebei are dominated by single-layer clouds in spring,summer and autumn,and double-layer clouds in winte.There are 7 types of precipitating ice clouds in various areas in Beijing-Tianjin-Hebei in the spring and summer,but 6 types and 5 types respectively in autumn and winter.In the summer,the precipitating ice clouds is dominated by deep convective clouds,accounting for 48.3%,but in other seasons nimbostratus are dominant.The distribution height and the maximum value of particle number concentration and ice water content are the highest in summer,the second in autumn,the third in spring,and the lowest in winter.The distribution height of maximum is still the highest in summer and lowest in winter,but higher in spring than in autumn.The maximum value of particle effective radius is the highest in summer,the second in spring,the third in winter and the lowest in autumn.In addition,in summer,these physical quantities vary with height in the four sub-districts of Beijing-Tianjin-Hebei.