Abstract:

Based on the hail observation data from seven stations in Pingliang of Gansu Province from 1965 to 2011，the temporal and spatial distribution of hail weathers and its climate features in Pingliang were analyzed in detail． At the same time，the stratification feature and radar echo characteristics were analyzed by using the hail observation data and the sounding data in hail days from 2003 to2011，and Doppler radar data of thunder cloud in Pingliang from 2009 to 2011． The results show that the high risk area of hail weather was located in Huating，Zhuanglang and Kongtong of Pingliang area． Hail weather occurred frequently in the 1980s and reduced from the 1990s． In a day，hail mainly occurred from 17: 00 to 22: 00． The instability of the upper troposphere ( from 300 to 600 hPa) is the
main characteristic of hail weather in Pingliang． Echo intensity of hail cloud in Pingliang was more than 50 dBZ，echo top height was more than 8 km，vertical liquid water content was 20 kg． m－ 2 ，strong center average height was about 6 km，the 45 dBZ echo height was 2 km higher than the height of 0 ℃ layer．

Key words: hail weather, climatic characteristic, radar echo characteristics

摘要：

利用甘肃平凉市７ 个气象台站１９６５ ～２０１１ 年冰雹观测资料详细分析了平凉冰雹的时空分布特征、气候特征。同时利用２００３ ～２０１１ 年平凉辖区内乡镇冰雹观测资料和冰雹日探空资料及２００９ ～２０１１ 年雷暴云多普勒雷达资料分析了平凉市冰雹日的层结特征及雷达回波特征。分析结果表明：平凉市冰雹高发区位于六盘山和关山山脉两侧的华亭、庄浪和崆峒区。１９８０ 年代是降雹的高峰期，１９９０ 年代至今冰雹发生的次数是减少的。一日中冰雹天气主要发生在１７ ～ ２２ 时。对流层上层（３００～６００ ｈＰａ）不稳定是平凉降雹的主要特征。平凉冰雹云回波强度＞ ５０ ｄＢＺ，回波顶高度在８ ｋｍ 以上，垂直液态含水量在２０ ｋｇ·ｍ － ２，强中心平均高度在６ ｋｍ 左右，４５ ｄＢＺ 回波高度高于０ ℃层高度２ｋｍ。

关键词: 冰雹, 气候特征, 回波特征