| 2008年浙江梅汛期暴雨的大尺度环流特征及其梅雨锋结构分析 |
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| 引用本文： | 张建海,沈锦栋,江丽俐.2008年浙江梅汛期暴雨的大尺度环流特征及其梅雨锋结构分析[J].高原气象,2009,28(5):1075-1084. |
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| 作者姓名： | 张建海 沈锦栋 江丽俐 |
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| 作者单位： | 1. 浙江省绍兴市气象局,浙江,绍兴,312000
2. 浙江省兰溪市气象局,浙江,兰溪,321100 |
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| 基金项目： | 浙江气象科技开放研究专项 |
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| 摘 要： | 通过客观分析资料和实况雨量, 对2008年浙江梅汛期降水的大尺度环流特征和梅雨期两次最强暴雨过程梅雨锋结构进行了对比分析\.结果表明, （1）2008年是浙江1999年以来最典型的梅汛期降水年份， 梅雨量较常年偏多20%左右， 期间共有5次系统性强降水过程。（2）在高层， 梅雨期间稳定强大的南亚高压东北侧的偏北大风提供了暴雨区高层强烈辐散； 在低层， 低空西南风急流把来自孟加拉湾和南海的水汽向暴雨区输送， 并与浙江北侧的偏东气流构成一个纬向切变， 造成了大量暖湿气流的辐合上升， 为暴雨区提供了良好的水汽和动力条件。（3）在对流层中层， 500 hPa环流形势在第一次暴雨结束后快速从单阻型向双阻型转变， 持续的双阻形势造成了长时间的阴雨天气。在温度场上， 强降水对应的梅雨锋区温度相对较低， 锋区没有明显的温度梯度， 但相当位温和水汽的梯度十分显著。（4）梅汛期两次最强暴雨过程梅雨锋结构的对比表明： 在分布形态上， 第一次暴雨接近纬向分布， 降水主要出现在锋前， 第三次暴雨则具有很强的经向度， 暴雨出现在锋区。在温湿结构上， 第三次暴雨发生时梅雨锋两侧的温度梯度远大于第一次暴雨。在涡度散度结构上， 第一次暴雨的正涡度大值区和辐合区在对流层中低层则较第三次暴雨深厚。
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| 关 键 词： | 浙江 梅雨锋 暴雨 环流特征 |
Analysis on Large-Scale Circulation Characteristic of Meiyu Rainstorm and Structure of Meiyu Front in Zhejiang Province during 2008 |
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| ZHANG Jian-hai,SHEN Jin-Dong,JIAN Li-li.Analysis on Large-Scale Circulation Characteristic of Meiyu Rainstorm and Structure of Meiyu Front in Zhejiang Province during 2008[J].Plateau Meteorology,2009,28(5):1075-1084. |
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| Authors: | ZHANG Jian-hai SHEN Jin-Dong JIAN Li-li |
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| Abstract: | Using the objective analysis data and observed rainfall, the large-scale circulation characteristic and the structure of Meiyu front of the two intensest rainstorm processes in Zhejiang Province in 2008 are comparative analyzed. The results are as follows: （1） The years of 2008 is the most typical Meiyu year since 1999, the accumulated rainfall is 20% much more than that in average years and has totally five systematic intense rainstorm processes during the whole Meiyu period. （2） On upper-level, northly wind which located on northeastward of the stable and strong south Asia high provides strong divergence field for rainstorm region. On low-level, southwest jet transports water vapour which comes from the Bay of Bengal and South China Sea to rainstorm region and constitutes a zonal shear line with eastly flow which located on northward of Zhejiang Province, the maintaining of upper and lower jet and much warm-wet moisture convergence provide favorable lifting mechanism and water vapour condition.（3） On middle-level, the circulation situation at 500 hPa has a sudden shift from single-blocking high type to double-blocking high type which lead to long-time rainy day. Intense rainstrom region corresponding to Meiyu front is relatively lower and there is no obvious temperature gradient, while the gradient of equivalent potential temperature and moisture is very obvious. （4） Comparative analysis of the structure of Meiyu front between the two intensest rainstorm processes indicates that the distribution of the first rainstorm is near to west-east and the mass rainfall located in the front of Meiyu front, whereas the third rainstorm has a meridional distribution and the main rainfall located in the middle of Meiyu front. As far as the structure of thermal-wet, the gradient of temperature of the first rainstorm are even more obvious than that of the third one. In vertical profile figure,addition, the distance of positive vorticity and negative divergence of the first rainstorm on the middle-low level of troposphere is deeper than the third one. |
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| Keywords: | Zhejiang Meiyu front Rainstrom Circulation characteristic |
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