State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences
Based on atmospheric reanalysis and precipitation, together with the winter and spring snow data over the Tibetan Plateau obtained by gauged stations and satellites, this study compare and validates the consistency of changes in different snow data sets on interannual scale. The impacts of winter and spring snow anomalies on the frequency and intensity of summer precipitation over the Eastern China are further explored. Combined with the atmospheric physical diagnosis and numerical simulation, the possible causes of the spatial difference in the impacts of snow anomalies on summer precipitation in China are investigated as well. The result of this study shows that: 1) the variation of snow depth observed by gauged stations is well consistent with that derived from the satellite data on the interannual scale. 2) The impacts of Plateau snow anomalies on the frequency and intensity of summer precipitation in China exhibit significant spatial differences. When there is more snow in winter and spring on the Tibetan Plateau, the frequency of summer precipitation increases obviously in North China, the middle and lower reaches of the Yangtze River and Northeast China, whereas the increase of rainfall frequency in North China is mainly dominated by the types of moderate rain and light rain, contrasting to the increase of heavy rain frequency in the middle and lower reaches of the Yangtze River. 3) During the years of more snow cover, the heat source over the Tibetan Plateau is weakened, resulting in occurrence of "negative-positive-negative" abnormal wave train structure on the 500hPa potential height, the strengthened and southward westerly jet, and the southward subtropical high ridge. The anomalous cyclonic circulation on the north side of the anomalous anticyclone in the Northwestern Pacific enhance the water vapor transport residing in the middle and lower reaches of the Yangtze River Basin. With the strengthened atmospheric vertical movement, the intensity and frequency of heavy precipitation is increased in this region. However, the region of North China is controlled by the circulation structure of "saddle" field, the occurrence frequency of small precipitation increases significantly, but the water vapor transport is weak, and the changes in precipitation intensity is not significant.