Abstract:

 Based on the routine meteorological data and CINRAD/CC Doppler radar products，the characteristics of environment conditions and radar echoes for 34 hail weather processes from 2009 to 2012 were analyzed and summarized in Akesu of the southern Xin-jiang．The results showed that the hail weather would be much more likely to occur when the temperature difference between 850 hPa and 500 hPa was more than 30 ℃ and the dew point temperature was more than 10．2 ℃ before the hail happened．CAPE index was effective on forecasting the hail when the diameter of hail was more than 10 mm， but it was limited to small －scale local hail weather． The weaker vertical wind shear from ground to 6 km height should also form hail． In additional，the suitable height of 0 ℃ layer and －20 ℃  layer were propitious to formation of hail weather． The radar echo characteristics of hail cloud were as follows: The composite reflectivity factor was more than 50 dBZ，the radial velocity field was often accompanied with the adverse wind area，and the portion of hail weather processes appeared storm top divergence feature．The 45 dBZ strong echo height was more than 9 km，and the vertical section had echo characteristics of hail weather such as overhang echo，vault echo etc．The top height of hail cloud exceeded 12 km from June to August，and that exceeded 11 km in May and September． The threshold of vertical integrated liquid content was 18 kg •m⁻² in May and 30 kg •m⁻² in other months． The solid big triangle label appeared continually at least 5 volume scans in hail index products．

Key words: Akesu, hail, environment condition, echo characteristic, index

摘要：

利用常规气象资料和CINRAD/CC雷达资料对2009～2012年34个冰雹天气个例进行了分析，统计归纳出南疆阿克苏冰雹天气发生前的环境条件和雹云雷达回波判识指标。结果表明：冰雹发生前期，当850 hPa与500 hPa温差30 ℃，地面露点温度10．2  ℃时，预示冰雹天气发生的可能性较大；对流有效位能在冰雹尺寸相对较大(10 mm)时指示效果较好，但对小范围局地冰雹的预报具有一定局限性；0～6km较弱的垂直风切变也能形成冰雹天气；适宜的0℃层和－20 ℃层高度有利于冰雹的产生雹云雷达回波具有的特征：组合反射率因子达到50 dBZ以上；径向速度场往往伴有逆风区出现，部分还出现风暴顶辐散特征;45 dBZ强回波核高度9 km，垂直剖面出现前悬回波穹窿等冰雹特征回波；回波顶高6～8月超过12 km，5月和9月超过11 km;垂直积分液态水含量阈值5月为18  kg•m^－2，其它月份为30  kg•m^－2；冰雹指数产品至少持续5个体扫出现实心大三角标识。

关键词: 阿克苏, 冰雹, 环境条件, 回波特征, 指标