基于MTM-SVD方法的黄河流域夏季降水年际变化及其主要影响因子分析

应用中国气象台站积雪日数资料和NCEP/NCAR再分析资料以及多锥度—奇异值分解方法 (MTM-SVD),分析了近50年来黄河流域夏季降水的时空变化及其影响因子.发现黄河流域夏季降水存在显著的2～3年周期.在准3年周期上黄河流域夏季降水对前冬青藏高原东部积雪日数有很好的响应,当前冬高原积雪日数以正 (负) 异常为主时,接下来的夏季黄河流域降水偏少 (多).这种响应存在年代际变化,在1983年之前最为明显,1983~1993年是个调整时期,1993年以后又开始明显.在准2年周期上黄河流域夏季降水对前冬西太平洋暖池SST有很好的响应,当前冬西太平洋暖池SST偏高 (低) 时,接下来的夏季黄河流域降水表现为东多 (少)西少 (多) 型.这一响应同样存在年代际变化.前冬高原积雪和西太平洋暖池SST是影响黄河流域夏季降水的重要因子.

Analysis of the Interannual Variation of the Summer Precipitation over the Yellow River Basin and the Effect Factors Based on MTM-SVD Method

By using the snow cover days data from the meteorology stations in China, the NCEP/NCAR reanalysis data, and the Multi Taper Method-Singular Value Decomposition (MTM-SVD), the spatial and temporal variation of the summer precipitation in recent 50 years in the Yellow River basin and its impact factors are analyzed. The prominent period of the summer precipitation is 2-3 years. There is a response of the summer precipitation in the Yellow River basin to the previous winter snow cover days over the Tibetan Plateau with a quasi-three-year period. When the previous winter snow cover days over the Tibetan Plateau is abnormally more (less), there is abnormally less (more) precipitation in the next summer in the Yellow River basin. This response has decadal variation, the most significant period appears before 1983 and there is an adjustment stage between 1983 and 1993, which again appears significantly after 1993. And there is a response of the summer precipitation in the Yellow River basin to the previous winter SST over the western Pacific warm pool with a quasi-two-year period. When the previous winter SST over the western Pacific warm pool is abnormally high (low), there is abnormally more (less) precipitation in the next summer in eastern Yellow River basin. This response also has decadal variation. The analyses show that the winter snow cover days over the Tibetan Plateau and the winter SST over the western Pacific warm pool are important factors to the summer precipitation in the Yellow River basin.