2012年汛期内蒙古大范围降水偏多成因分析

利用内蒙古113测站1961—2012年6—8月降水资料、1961—2012年NCEP/NCAP再分析资料数据集、国家气候中心太平洋海温资料,采用统计诊断、相关分析等方法,对2012年汛期(6—8月)内蒙古降水特点及影响因子进行分析,探讨2012年汛期(6—8月)内蒙古大范围降水偏多的可能影响因素。通过对近50a汛期降水年际变化特征及海温、印度夏季风活动、中纬度阻塞高压的影响进行分析,结果表明:2012年汛期(6—8月)内蒙古大范围降水偏多,主要表现为降水过程频繁、覆盖范围广、强降水过程多,多站突破历史纪录;主要原因为内蒙古汛期降水在减少的年代际背景下,年际变化规律明显,2012年汛期出现多雨的概率较大;2012年汛期北半球500hPa高度场主要特征相似内蒙古典型多雨年的环流形势;La Nina事件在2012年3—5月结束,有利于汛期降水偏多;印度夏季风异常偏强、乌拉尔山高脊和鄂霍次克海高压偏强、贝加尔湖地区受低槽控制均是影响2012年内蒙古汛期大范围降水偏多的重要因素。

Cause Analysis on Large-scale and more Rainfalls during the Flood Season in the Inner Mongolia Area in 2012 Years

The characteristics of rainfalls and the influencing factors were analyzed based on the data of monthly rainfall from 113 stations of Inner Mongolia, NCEP reanalysis data and the SST in the Pacific Ocean of National Climate Centre by the methods of correlation analysis, statistical diagnosis. The reasons o the wide rage of more rainfalls in the Inner Mongolia in 2012 flood season were discussed. Analysis the climate background of the flood season, SST, India summer monsoon activity, mid-latitude blocking high, the results showed that： The characteristics of the wide of rainfalls in the Inner Mongolia in 2012 were frequent, wide coverage, strong and many stations were exceeding the records. The reasons of the wide and more rainfalls were the precipitation had obviously interannual variation under the interdecadal background of the less rainfall and more rainfall was probably. The 500hPa circulation over the northern hemisphere of the flood season in 2012 was the same as the circulation of the typical rainy years in the Inner Mongolia area. La Nina finished in the 3-5 month was beneficial to the more rainfalls of the flood season. Indian summer monsoon was strong anomalies, ridge over the Ural and high over the Okhotsk sea were strong, flood season and lake Baikal was controlled by trough. Those were all reasons why flood season rainfalls were more in the Inner Mongolia area.