青藏高原东北侧夏季降水的气候特征分析

利用西北地区均匀分布的126个地面测站,采用REOF和模糊聚类方法对降水的空间特征进行研究发现,青藏高原东北侧是西北地区夏季降水最为敏感的自然区,主要雨季为7～8月,几乎占全年总降水的一半,该区域少雨年的概率大于多雨年,旱年和多雨年交替出现。6月降水在近40a里呈上升趋势,7月降水总体变化不大,8月呈下降趋势,从降水线性趋势来看,整个夏季降水无明显变化。另外,气温距平和降水距平百分率具有明显的反位相变化关系,近40a来气温呈缓慢升高趋势。

Analysis on the Climatic Characteristics of the Precipitation in Northeastern Side of Tibetan Plateau in Summer

Based on precipitation data in 126 surface stations in Northwest China, using REOF and Blur-clustering method, the spatial characteristics of summer precipitation in Northwest China were analyzed in the paper. Results show that the northeastern side of Tibetan Plateau is the most sensitive region to summer precipitation in Northwest China, the rainy season (July to August) precipitation is mostly a half of that in a year, years with less rain are more than rainy years in the region, and dry and flood years are alternant. Precipitation trend in June is ascending in recent 40 years, changing slowly in July, and descending in August, from the liner trend, the summer precipitation is changing unconspicuously. Moreover, temperature departure and precipitation departure percent present reverse phase, and temperature is rising in recent 40 years.