2017年山东夏季降水特征及预测初探

Study on characteristics of summer precipitation in Shandong in 2017 and its prediction

2017年夏季山东平均降水量为453.0 mm,较常年(400.3 mm)偏多13.2%,降雨过程较多,降水空间分布不均匀。夏季北半球极涡为单极型分布,中高纬整体以纬向环流为主,西太平洋副热带高压较常年同期强度偏强,西伸脊点较常年偏西。6月降水主要由华北、东北冷涡偏强造成,7月和8月副热带高压偏强、偏西,副热带高压边缘暖湿气流为山东降水提供了充足水汽,导致7、8月降水偏多。此外,进一步分析了历史上相似年份确定和客观预测方法对山东夏季降水预测的作用。

The mean amount of summer precipitation in Shandong in 2017 was 453.0 mm, 13.2% more than the normal value （400.3 mm）. The precipitation events were more and the spatial distribution was uneven. The polar vortex in the summer of northern hemisphere was characterized by monopole type distribution. Zonal circulation prevailed in middle and high latitudes. The intensity of western Pacific subtropical high was higher compared with the same period of normal years and the west-extending ridge was to the west of that in normal years. The precipitation in June was mainly caused by stronger cold vortex in North China and Northeast China, while the more precipitation in July and August resulted from stronger and westward subtropical high and abundant water vapour in the warm and wet air current near it. The importance of similar years and objective prediction method were further analyzed.