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.