石家庄的云、降水和水汽特征

应用1972~2003年石家庄17个站的云、降水资料分析了各类云的发生频率及其降水特征,结果表明:全年而言,积层混合云出现频率高,且降水概率、降水率较大;夏季积状云出现频率高,降水概率、降水率大,对两者增雨机会多。应用2000~2004年常规天气图,对造成石家庄降水的天气系统、云、降水、水汽进行分析,结果显示:西来槽、冷切变、东蒙冷涡和华北低涡出现频率较高,造成的降水次数多,实施增雨的机会多;气旋类、西南涡出现频率低,但过程雨量大,降水持续时间长,是人工增雨不可忽视的天气系统;冷涡类降水时间最短,降水强度大,对其实施人工增雨,作业时机的把握很重要。石家庄上空的水汽含量呈单峰型季节变化,空中水汽资源量明显地受到大气环流和天气系统影响。对水汽通量场分析表明,对流层中高层水汽多来自于孟加拉湾和南海,低层水汽主要来自于东海、黄海,地面近地层水汽源多为黄渤海。

Analysis of Characteristics of Clouds,Precipitation and Water Vapor over Shijiazhuang

Based on the observations of clouds and rainfall from 17 stations in Shijiazhuang,an analysis is conducted on the occurrence frequencies of various clouds and their precipitation characteristics.The results show that the emergence probability and the precipitation rate of cumulus-stratus mixing clouds in the whole year and cumulus in summer are high,so there is a great deal of operation opportunities for rain enhancement.Using conventional sounding data,the weather systems,clouds,precipitation,water vapor resulting precipitation in(Shijiazhuang) are analyzed.The results indicate that the emergence frequencies of the westerly trough,cold shear line,cold vortex in East-Mongolia and low vortex over North-China are high,and the opportunities for precipitation and rain enhancement are greater.The occurrence probabilities of cyclones and the southwest vortex are low,but the rains induced by them has large amount and long duration.So they are important for rainfall enhancement.The short-range heavy rains induced by cold vortexes have short duration,but large amount,are(also) important for rain enhancement operations.The water vapor amount over Shijiazhuang shows a single-apex(seasonal) change pattern,and is influenced obviously by the atmospheric circulation and weather systems.Analysis of the related moisture flux fields indicates that the moisture in the middle-upper level of the troposphere comes mainly from the Bay of Bengal and the South China Sea,and that in the lower level from the East China Sea and the Yellow Sea;the moisture sources of the surface layer are over the Yellow Sea and the Bohai Sea.