2008年1月中国南部低温雨雪冰冻天气特征及其与东亚大气环流异常探讨

Characteristics of the Freezing Rain/Heavy Snow Process in South China and the Anomalies of Atmospheric Circulation over East Asia in January 2008

根据NCEP/NCAR提供的1968—1996年全球逐月、2008年1月全球逐日再分析资料以及中国气象局提供的降水资料,分析了2008年1月中国南部持续低温雨雪冰冻天气期间东亚地区中低空大气环流异常特征。结果表明,乌拉尔山阻塞高压和地面蒙古冷高压是这次灾害性天气重要的冷空气源地;700 hPa异常偏强的低空西南风急流以及低空急流大风速中心随时间沿急流轴的传播为此次低温雨雪冰冻天气提供了充足的动量、热量和水汽;850 hPa流场西太平洋上空异常东南风、印度洋上空异常西南风以及850 hPa垂直速度场中国南部大陆异常上升气流,在很大程度上影响着2008年1月中国南部的天气;赤道辐合带、西太平洋副热带高压以及南支槽的异常,致使东亚上空不仅存在异常的南支槽前西风带水汽输送和西太平洋副热带高压西南侧东风带水汽输送,还存在异常的由印度洋经孟加拉湾向中国南方大陆的水汽输送。

Abstract：Based on the precipitation data from CMA and NCEP/NCAR global monthly reanalysis data from 1968 to 1996 and daily reanalysis data in January 2008 ,the atmospheric circulation anomaly over East Asia during the freezing rain/heavy snow process in South China in January 2008 was analyzed. The result shows that the anomalous strength of the Ural blocking high and the Mongolia cold anticy- clone were the main cold air source for the freezing rain/heavy snow process in South China in January 2008. The anomalous strength of low level south-west jet at 700 hPa and the transmission of the high wind speed center along its axis produced abundant momentum, heat and water vapor. The weather in South China in January 2008 was severely influenced by the anomalous southeast wind at 850 hPa stream field over west Pacific, the anomalous southwest wind over Indian Ocean and a large range of upward current at 850 hPa vertical velocity field over South China. Moreover, the anomaly of equatorial belt of convergence, West Pacific subtropical high and the southern branch of currents brought more moisture to South China in January 2008.