夏季青藏高原低值系统与地气温差及我国降水的联系

基于青藏高原低涡和切变线（简称高原低值系统）年鉴、国家气象站地面观测资料及ERA-Interim再分析资料，分析了高原低值系统多、少发年夏季高原地气温差变化的差异及其对我国降水的影响。结果表明：（1）高原夏季地气温差对高原低值系统的发生和移动有明显的影响。在低值系统频发区，多发年的地气温差明显比少发年高。（2）我国西部的青藏高原中部、东北部及西南地区在多发年降水偏多，高原南部和东南部则在少发年降水偏多；我国东部地区，多、少发年降水差异自南至北呈“+”、“-”、“+”、“-”、“+”的差值带分布特征，即华南、江淮流域、华北和东北地区降水在多发年偏多，江南地区和黄淮流域降水则在少发年偏多。（3）高原低值系统多、少发年夏季对流层的环流系统及相应垂直速度、水汽输送变化有明显差异，并影响青藏高原和我国降水的变化。在高原地区，多、少发年之间环流的差异是受高原东部和南部的气流辐合（辐散）场、相应的垂直运动差值上升（下沉）、水汽输送辐合（辐散）区域变化的影响；在东部地区，则是受南海到华南、长江流域、华北到东北为气旋（反气旋）环流系统及其间辐合（辐散）带变化的影响。

Relationship between the Tibetan Plateau Vortex & Shear-Line and Ground-Air Temperature Differences in Summer and the Precipitation in China

By using the Tibetan Plateau Vortex & Shear-Line (PVSL) yearbook, the ground observation station data of the National Meteorological Information Centre and the ERA-Interim reanalysis data, the difference of summer plateau ground-air temperature between multi- and less- years of PVSL and its impact on precipitation in China are analyzed. The results show that: (1) The difference of summer plateau ground-air temperature has a significant impact on the occurrence and movement of the PVSL. In the areas of the PVSL frequent occurrence, the ground-air temperature difference in multi-year is obviously higher than that in less-year. (2) More precipitation occurs in the central, northeastern and southwestern parts of the Tibetan Plateau in western China in multi-yearmore precipitation, while more precipitation occurs in the southern and southeastern parts of the plateau in less-year. From the south to the north in eastern China, the difference of precipitation in multi- and less-years is shown as “+”, “?”, “+”, “?”, “+”. In other words, the precipitations in South China, the Yangtze-Huaihe River Basin, North China and Northeast China are more in multi-year, while the precipitations in the Jiangnan region and the Huang-Huaihe River Basin are more in less-year. (3) There are obvious differences in the tropospheric circulation system and corresponding vertical velocities and water-vapor transportation in summer of multi-year and less-year of PVSL, which affect the precipitation changes in the Tibetan Plateau and China. In the Tibetan Plateau area, the difference of circulation system between multi-year and less-year is affected by the wind field convergence (divergence) over the Eastern and Southern plateau as well as corresponding vertical velocity rise (sink) and water-vapor transportation convergence (divergence). In the eastern China, the difference is affected by the changes in the cyclonic (anticyclonic) circulation system and its convergence ( divergence ) zone from the South China Sea to South China, the Yangtze River Basin, North China to Northeast China.