青藏高原冬季降水时空分布特征研究

青藏高原冬季降水的气候特征认识对高原冬季雪灾的防御有着重要意义。基于青藏高原54个气象站1971~2010年冬季(12~2月)逐月降水量资料,利用现代统计方法分析了青藏高原冬季降水的时空分布特征及突变现象,利用经验正交函数(EOF)和旋转经验正交函数(REOF)概括出高原冬季降水的6种主要空间分布型以及区域性特征进行分析。结果表明:冬季降水分布不均匀,偏东偏南部降水量相对较多,冬季降水在12月最少,2月最多;EOF对青藏高原地区冬季降水分解为6种模态,全区一致型、南北部型、东西部型、川西型、高原腹地型和西部型模态;EOF第1模态时间系数表明高原大部分地区冬季降水在20世纪90年代有显著增加、且存在14年左右的周期变化特征。REOF分析表明,高原地区冬季降水的局地特征显著,而高原腹地与中东部地区变化特征显示了高原冬季降水的主要变化特征,与EOF分析第1模态的变化特征较为一致。

Study of Spatial and Temporal Characteristics on Winter Precipitation in Tibetan Plateau

Understanding the climatic characteristics of the Tibetan Plateau winter precipitation is useful for Plateau winter snowstorm defense. With the modern statistical methods to analyze the feature of temporal-spatial distributions and the abrupt phenomenon variation of the Tibetan Plateau winter precipitation according to the monthly precipitation materials in 1972-2011 winter（ December to February） from 54 Tibetan Plateau stations. Applying empirical orthogonal function（ EOF） and rotation empirical orthogonal function（ REOF） to divide the plateau winter precipitation into 6 main spatial distribution and analyze the regional characteristics of Tibetan Plateau winter precipitation. The conclusion is： in December has the least winter precipitation,while in February has the most. The amount of precipitation is not a uniform distribution,which is relatively more in east and south area. The 6 types of EOF： the region consistent type,the north and south type,eastern and western type,Kawanishi type,Plateau hinterland type and western type. The time series of the first EOF mode showed that the winter precipitation in most plateau region in the 1990 s has a significant increase and 14-year cycle characteristics. REOF analysis shows： the local characteristic of Tibetan Plateau winter precipitation is significant. The eastern part and hinterland of Tibetan Plateau winter precipitation show the main feature of Tibetan Plateau winter precipitation and are similar to the change of the first EOF mode.