| “8.12”甘肃大暴雨特征分析 |
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| 引用本文： | 许东蓓,刘抗,孟丽霞,车玉川,程鹏,刘新伟,宋强.“8.12”甘肃大暴雨特征分析[J].干旱区地理,2013,36(2):245-252. |
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| 作者姓名： | 许东蓓 刘抗 孟丽霞 车玉川 程鹏 刘新伟 宋强 |
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| 作者单位： | 兰州中心气象台,甘肃兰州,730020 |
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| 基金项目： | 国家自然基金项目"西北地区跨季强干旱事件的形成机理研究"41175081 |
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| 摘 要： | 2010年8月10～13日，甘肃省河东出现了中到大雨，局地暴雨或大暴雨，是舟曲山洪地质灾害气象应急响应开始后迎来的第一场区域性暴雨过程，对前方救灾抢险工作造成严重威胁。利用实况观测资料和NCEP再分析资料对大暴雨过程的天气特征、水汽条件、动力条件、不稳定条件等进行综合分析，并总结了暴雨过程的中尺度云团特征及雷达回波特征。结果表明：此次暴雨过程持续时间较长，但大暴雨出现时段集中，雨强大，危害性强。副高强盛，北部冷空气分裂南下，青藏高原切变线活动频繁，是本次暴雨过程的主要环流特征。500 hPa锋区和700 hPa低涡切变线是造成暴雨天气的直接影响系统。低层正涡度区、水汽辐合、上升运动、正螺旋度中心以及层结不稳定等因素为暴雨产生创造了热力、动力和能量条件。此次暴雨的触发机制是低层中尺度切变线的发展和维持、偏南暖湿气流的增强，以及低层辐合高层辐散的大气上下层抽吸作用。多个中β尺度对流云团沿700 hPa切变南侧发展东移，表明本次大暴雨过程中存在明显中小尺度系统，其中低层气旋式辐合、高层辐散流场的配置是降雨范围及强度增大的重要原因。
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| 关 键 词： | 甘肃 大暴雨 特征 分析 |
| 收稿时间： | 2012-05-16; |
Characteristics of heavy rainfall occurred on 12 August 2010 in Gansu, China |
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| XU Dong-bei,LU Kang,MENG Li-xia,CHE Yu-chuan,CHENG Peng,LU Xin-wei,SONG Qiang.Characteristics of heavy rainfall occurred on 12 August 2010 in Gansu, China[J].Arid Land Geography,2013,36(2):245-252. |
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| Authors: | XU Dong-bei LU Kang MENG Li-xia CHE Yu-chuan CHENG Peng LU Xin-wei SONG Qiang |
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| Institution: | （Lanzhou Centre Meteorological Observation，Lanzhou 730020，Gansu, China） |
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| Abstract: | The prediction for heavy rainfall in northeastern Tibetan Plateau is of vital importance in the work for disastrous weather forecast around northwest Region of China. There are many regional heavy rainfall and local severe convection in Gansu province which result in geological disasters in high frequency in early and middle August in 2010. The heaviest rainfall in flood season in 2010 was the one happened in 11～13 Aug in the east of the Yellow River in Gansu，which is famous for its intensity，coverage and duration. Several characteristics from different aspects of this heavy rainfall event were comprehensively analyzed based on the observed station data and NCEP reanalysis data，such as precipitation condition，circulation background，moisture conditions，dynamic condition and convective instability factor. Besides，the characteristics of the mesoscale cloud cluster and the radar echoes were summarized. The results show that:（1）Even though the event lasted for a long time，the heaviest section just occurred in a short time with a strong intensity and destructive damages. The main circulation background，which includes strong subtropical high，southward action of northern cold air and active Tibetan Plateau shear lines，is favorable for the formation of the rainfall. （2）The direct influence systems are the front at 500hPa and the low vortex with shear line at 700hPa. （3）The properly configuration of many factors provides a good condition for developing a rainfall in dynamic，thermodynamic and energetic environmental conditions，these factors include low level vortex maximum，water vapor convergence，ascending motion，positive helicity center and instable energy of stratification. （4）The trigger mechanism of the rainfall is the development of the mesoscale shear line on the low level，the quick strengthened warm-moist air from the southwest and the suction action of the atmosphere. During 02～08 on August 12，The shear line in the middle-southern Gansu developed and then led to the heavy rainfall event. （5）It is indicated that there was a obvious mesoscale system when several meso-β-scale convective cloud cluster moved to the east and enhanced along the south shear line at 700 hPa. The typical patterns which have convergence in the bottom layer and divergence in upper layer in the meso-β-scale convective cloud cluster caused the rainfall developed to a serious level. Therefore，several mesoscale cloud clusters emerged continuously and then the precipitation reached the maximum one by one. （6）Radar echo characteristics show that cyclonic convergence flow field is one of the important elements for strengthening the rainfall. The main innovation point of this paper is to improve the forecast technique for heavy rainfall by using the conventional meteorological data and the short-term monitoring data. |
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| Keywords: | Gansu heavy rainfall characteristics analysis |
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