Study On The Relationships Between The Temporal&Spatial Of Snow Cover In Winter And Spring Over Tibetan Plateau And The Summer Precipitation In Eastern China

The snow cover in winter and spring over Tibetan Plateau(TP) as a "signa"of forecasting summer precipitation in eastern China, has been widely used in short-term climate prediction operation practices. However, the "signal" has still large uncertainties, the intrinsic link between temporal&spatial relationship also requires further study. Through a series of statistical diagnosis analysis and numerical simulations to study relationship between the snow cover in winter and spring over Tibetan Plateau and summer precipitation in eastern China. First, snow data from satellite and from station observed was compared, select data on snow representative for the quality inspection; using EOF and REOF method and nearly30years snow over Tibetan Plateau in winter and spring different time periods of snow temporal anomalies were analyzed; By SVD method on the snow cover over Tibetan Plateau in winter and spring different time scales and temporal relationships between summer precipitation in China were analyzed; Numerical simulation method though designing sensitivity tests confirm the above statistical relationship. The main conclusions are as follows:(l)The distribution pattern of the two kinds of snow data in the regions of snow stability is similar, the snow depth are in the Northeastern China, northern Xinjiang and the TP. Two kind data have obvious difference in seasonal snow region, especially in the Huihe River basin and the Yangtze River, the observed snow depth is greater than the snow from passive microwave remote sensing. On average, the snow depth from two kind data in the three regions (Northeastern China, northern Xinjiang and the TP) is the same. However, two data have difference on interannual evolution and trend in northern Xinjiang and the southeastern TP. However, in the southeastern TP, the station observed snow depth was greater than remote sensing, but the pattern is inversed in the northern Xinjiang. In the past30years, two kinds of snow depth in northern Xinjiang and TP, interannual trends are the same, northern Xinjiang is an increasing trend, which has a decreasing trend in the TP. The correlation between two kinds of data is significant in the northern Xinjiang, Northeast and TP. Therefore, the "signal" of two snow data over TP providing to summer precipitation prediction of eastern China is equal. The difference of two kind data do not affects application of TP snow "signal" in predication of summer precipitation over eastern China.(2) Spatial and temporal characteristics of the snow changes obviously with the seasons, and the regional characteristics are significant. At the beginning of the winter, the snow show "South-North" anti-phase distribution which presents the southeast-northwest inversely related to distribution to the depth of winter, spring and then presents "East-West" anti-phase distribution. The whole process embodies the characteristics of snow accumulated to the ablation process space changes. In the past30years, the snow on the plateau east-southeast and along the Himalayas a decreasing trend, while the Kunlun Mountains area of the plateau in northern and western Tibet plateau hinterland increasing trend, mainly snowy mainly in the1980s,1990s and2000years after the plateau less snow.(3) Snow cover sensitive areas from early winter to the middle of winter to this spring seasonal variations of very significant. Extraordinarily sensitive area of the plateau snow from11-1to2-4this period of time is more stable, just goes with the seasons, scope and value has been expanded. And snow started to build in October to December and March to May snow ablation of sensitive areas changed greatly, using REOF to the western part of the plateau characteristics of a more acute, easy-to-grasp of the local feature.(4) The relationship between the TP snow cover and summer precipitation in China mainly Plateau snow and northeast, the Loop, the Yangtze River, the Huai he River, southern and southern China summer rainfall. Plateau different regions and different time periods of snow and more than a few regional summer precipitation relationship differences. The south-central and southeastern snow increase (decrease) in October to March, the Northeast China Plain and the Yangtze River valley summer rainfall anomalies increase (decrease), while the loop and South China summer rainfall anomalies decrease (increase), and the plateau south of the snow and the former than the latter related significantly. Spring southeastern snowincrease (decrease) in southern China summer abnormal decrease (increase). Increase in spring from March to May after the western end of the plateau and eastern snow, summer rainfall in north-eastern and middle reaches of the Yangtze River abnormal increase (decrease), while the loop and South China increased precipitation.(5) The central and western Tibet northern Tibetan Plateau winter and spring snow anomaly (October to April) Increase (decrease), the western Northeast, South Tibet Valley, Jinsha River Basin and the southern region summer precipitation abnormal increase (decrease) in2-4months of snow in central and western Tibet summer precipitation of the four regions the most significant. Spring from March to May after the western end of the plateau snow increase (decrease), summer rainfall increase (decrease). Plateau north of Qilian Mountains and the Kunlun Mountains from December to April the snow abnormal increase (decrease) in the northeast of the southern summer rainfall anomalies decrease (increase), and the Huaihe River Basin summer rainfall anomalies increase (decrease). And the Qilian Mountain area in winter and spring snow has been working with summer precipitation in the Huaihe River Basin, there was a significant positive correlation.(6) Increasing the surface albedo of Tibet Plateau, a corresponding increase in summer precipitation in the Yangtze River Basin, and the eastern part of South China reduced precipitation, especially surface albedo change from December to March, the effect is significant. The numerical simulation results confirm the statistical results. Snow cover on summer rainfall in China there is a good relationship, especially the southern part of the Qinghai-Tibet Plateau snow from December to March. The difference larger area in South Midwest South Midwest summer rainfall decreased when plateau in winter and spring surface albedo increase.