西南低涡的统计特征及其对湖北降水的影响

The Statistic Characteristics of Southwest China Vortex and its Effect on Precipitation of Hubei Province

在较长时间序列的基础上,利用客观分析统计的结果,阐述了西南低涡的气候特征。对近60年西南低涡个例的分析表明:利用再分析资料进行西南低涡的历史统计是可行的,能够反映出西南低涡的气候态特征,并且与实际观测事实相符,当西南低涡发生异常时,高空西风急流的位置会发生明显变化,西南低涡偏多时所对应的西风急流偏南明显,偏少时则北偏明显;通过其与降水的分析表明,西南低涡与湖北省降水相关较好,全省大部地区相关系数达到了0.35以上,尤其对极端降水的指示意义较为明显。此外,西南低涡与海温场也具有较好的相关性。

Use the objective analysis and statistical result based on a long time series data, southwest vortex＇s climate character has been revealed. Southwest vortex＇s analysis shows that using reanalysis data to analyse southwest vortex＇s statistic character is feasible, which can reflect the climate state character of the southwest vortex, and consistent with the observed fact. When an exception occurs on southwest vortex, upper westerly jet＇s location will be changed obviously, when southwest vortex generated more than normal the corresponding westerly jet drifts to the northern side, the reverse is also true. The analysis on the relation between the precipitation and southwest vortex＇s counts shows that they have a high correlation, and the correlation coefficient in most parts of the province has reached 0.35, especially has the indication to anomaly precipitation. Besides, the southwest vortex and SST have a high correlation.