黄河中游夏季降水异常的先兆特征和预测方法

Characteristics of Anomalous Sign and Prediction of Summer Precipitation in the Middle Reaches of Yellow River

本文利用黄河中游61站降水资料,分析了其变化规律和同期及前期环境场特征,并建立了夏季降水预测模型。研究发现:黄河中游夏季降水具有显著的年际变化特征,显著周期在3年左右;黄河中游夏季降水主要受到同期东亚高空急流、西太平洋副热带高压(以下简称副高)以及贝加尔湖附近低槽的影响,当急流和副高偏强(弱)偏北(南)、贝加尔湖附近高度场偏低(高)时,黄河中游降水偏多(少)。另外,前期秋季南方涛动指数、北非副热带高压(20°W^60°E)、南海副热带高压(100°~120°E)、北半球副高强度及北半球极涡强度发生异常时,对夏季环流产生影响,从而影响黄河中游夏季降水,据此,建立预测模型。评估发现该模型具有较强的预测能力,可用于黄河中游夏季降水的定量预测。

Using 61 station precipitation data in the middle reaches of Yellow River, characteristics and am bient field of summer precipitation in the middle reaches of the Yellow River are analyzed and one predic- tion model is established in this paper. The research result reveales that summer precipitation in the middle reaches of Yellow River is mainly affected by the East Asian jet stream, the West Pacific subtropical high and the low trough in the vicinity of Lake Baikal. That is, when the East Asian jet stream and the West Pacific subtropical high are stronger, lying more northward, and the Baikal trough is deeper, more rains fall in this region, and vice versa. Besides, the autumn Southern Oscillation, the North African subtropi- cal high, the South China Sea subtropical high, the Northern Hemisphere subtropical high and the North- ern Hemisphere polar vortex can all exert an impact on the summer circulation and precipitation in the mid dle reaches of Yellow River. Therefore, a forecast model for summer precipitation in the middle reaches of the Yellow River is established by using the above factors. Assessment shows that this model has good prediction ability and can be used for quantitative prediction of summer precipitation in the middle reaches of Yellow River.