| 1981—2000年四川夏季暴雨大尺度环流背景特征 |
| |
| 引用本文： | 陈栋,顾雷,蒋兴文.1981—2000年四川夏季暴雨大尺度环流背景特征[J].南京气象学院学报,2010,33(4):443-450. |
| |
| 作者姓名： | 陈栋 顾雷 蒋兴文 |
| |
| 作者单位： | 1. 中国气象局,成都高原气象研究所,四川,成都,610072
2. 中国科学院,大气物理研究所,季风系统研究中心,北京,100080 |
| |
| 基金项目： | 中国气象局成都高原气候研究所基本科研业务费专项 |
| |
| 摘 要： | 利用四川盆地及周边地区1981—2000年逐日降雨量资料和ECMWF逐日4次再分析资料,合成分析近20 a发生在四川夏季的22次典型暴雨过程的大尺度环流背景特征。结果表明,四川夏季暴雨的发生具有显著的轴向分布性和区域移动性特征。西伸的西太平洋副热带高压、北上东进的伊朗高压及高原东部的弱高压、活跃的孟加拉低压和影响四川北部的中高纬长波分裂的低压槽共同作用形成了四川暴雨发生阶段的特殊的＂鞍＂型大尺度环流背景。在＂鞍＂型大尺度环流背景下,有利于西南支孟加拉湾水汽和南海水汽输送在四川盆地形成低层辐合,同时在高层形成西南—东北的轴向急流辐合带,水汽输送散度负的大值区即为暴雨发生的主要落区。此外,四川北部在两高压相夹下,有利于高纬度大尺度的两高一脊环流调整产生的弱槽携带冷空气影响四川盆地,形成高层弱冷干与低层强暖湿的强垂直对流不稳定。对比40 a四川夏季平均环流可知,导致四川夏季暴雨发生的＂鞍＂型大尺度环流背景特征极为显著,具体表现为：西太平洋副热带高压西伸到110°E附近,青藏高原西侧伊朗高压偏北、青藏高原高层南压高压偏东,而高原低层有弱高压,四川北部冷槽显著偏南。
|
| 关 键 词： | 暴雨 大尺度环流 合成分析 “鞍”型背景 |
Characteristics of Large-scale Circulation Background of Summer Heavy Rainfall in Sichuan during 1981-2000 |
| |
| CHEN Dong,GU Lei,JIANG Xing-wen.Characteristics of Large-scale Circulation Background of Summer Heavy Rainfall in Sichuan during 1981-2000[J].Journal of Nanjing Institute of Meteorology,2010,33(4):443-450. |
| |
| Authors: | CHEN Dong GU Lei JIANG Xing-wen |
| |
| Institution: | 1.Chengdu Institute of Plateau Meteorology,China Meteorological Administration,Chengdu 610072,China;2.Center for Monsoon System Research,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100080,China) |
| |
| Abstract: | Based on the observed daily precipitation data and ECMWF reanalysis data from 1981 to 2000,the characteristics of large-scale circulation background of twenty-two typical processes of summer heavy rainfall in Sichuan are analyzed by the composite method.Results show that there are obvious characteristics of axial distribution and regional moving for summer heavy rainfall in Sichuan.The special large scale background of saddle pattern in the stage of heavy rainfall of Sichuan is formed by the combined action of the western Pacific subtropical high shifting westward,the Iran high center strengthening and moving northeastward,the active low pressure of the Bay of Bengal,and low pressure troughs in the northern part of Sichuan separated from the eastward propagation and adjustment of atmospheric long waves at middle and high latitudes.Under the background of saddle pattern,it is favorable for the formation of the low level convergence of water vapor transportation from the Bay of Bengal and South China Sea and the upper level convergence belt from southwest to northeast over Sichuan.The main areas of heavy rainfall are corresponding to the negative center of water vapor transportation divergence.Moreover,the strong instability of vertical convection（weak cold dry air in the upper layer,and strong warm moist air in the low layer） was caused over northern Sichuan Basin between the two high pressure systems,which is favorable for cold air activity by the low pressure troughs separated from the eastward propagation and adjustment of atmospheric long waves at middle and high latitudes.Contrast to summer average circulation from 1961 to 2000 in Sichuan,it is very remarkable for the special large scale background of the saddle pattern leading to the summer heavy rainfall in Sichuan,namely the western Pacific subtropical high shifting westward near to 110°E,the Iran high center being northward,the South Asia high being eastward,the weak high pressure system occurring at low level over the Tibet Plateau,and the low pressure troughs being southward over the northern Sichuan. |
| |
| Keywords: | heavy rainfall large-scale circulation composite analysis saddle pattern background |
| 本文献已被 维普 万方数据 等数据库收录！ |
|
