内蒙古春季降水的气候特征及预测思路

采用1961—2016年春季(3—5月)内蒙古逐月降水资料,应用统计相关分析、REOF,对比分析等方法分析研究了内蒙古地区春季降水类型的气候特征以及海洋和大气环流特征。可以发现,内蒙古春季降水具有明显的地域性特征,分为4个类型:全区偏少型,全区偏多型,中西部偏多、东部偏少型,东部偏多、中西部偏少型。研究结果说明,春季降水的大气环流形势受ENSO事件影响。AO的正、负位相对内蒙古不同地区造成不同影响,正位相时有利于中西部降水偏多,负位相时有利于东部偏多。西伯利亚高压偏强,东亚大槽偏弱、偏西,冬季青藏高原积雪偏多,西太平洋副热带高压偏强、偏西,降水落区处在低压槽后,冷空气较为活跃,配合暖湿水汽输送条件,冷暖气流在内蒙古地区交汇便形成多雨区;反之亦然。研究结果对预报员预测思路具有预测指导意义。

Climate Characteristics of Spring Precipitation in Inner Mongolia and Prediction Methods

Based on using the monthly spring precipitation dataset observed Inner Mongolia (IM) during the past 56 years (1961-2016), characters of spring precipitation, the oceans and the atmospheric circulation were investigated by employing the method of statistical, REOF and comparison analyses. The comparison analyses indicate that IM spring precipitations significantly present spatial features. Therefore, we summarized the spring precipitations into four types, including rich and less rainfall over the whole region of IM, rich in the middle-western area and less in the eastern region, rich in the eastern area and less in the middle-western region of IM. The results shown that the ENSO events conduct influence on the atmospheric circulation directly, and then, affecting the spring precipitation indirectly. Additionally, positive and negative phases of the AO affect different regions in IM. A positive AO commonly corresponds to a rich rainfall spring in the middle-western region and a negative AO generally results in a less precipitation spring in the eastern area of IM. Besides, a strong Siberia High, a weak and western location of the East Asian trough, a rich snowfall in the Qinghai-Xizang Plateau during the previous winter with a strong and westward extended West Pacific subtropical high and the favorable warm-wet currents from the southwestern may help for spring precipitations in IM. A rich rainfall region can be viewed when the cold air in an active style and meet the warm-wet current. Oppositely, a reduced spring rainfall would appear in IM. Results of this study should be useful for producing spring precipitation forecasts.