Spring snowmelt variations over the Tibetan Plateau and its influences on spring and summer precipitation

Both snow and precipitation are vital components of the water cycle and hydrological system, so the snow-precipitation feedback could be crucial for investigating land-atmosphere interaction and climate variability. Seldom studies have focused on the contributions of snow variations to precipitation anomalies over the Tibetan Plateau (TP). In this study, spring snowmelt (SSD, Spring Snow water equivalent Differences) variations over the TP and its influences on spring and summer precipitation and the associated physical mechanisms during 1979-2014 are investigated. Results show that the leading mode of the interannual SSD over the TP exhibits a same-sign anomaly pattern, with an intense centre over the western TP. The SSD shows significant relations to spring and summer precipitation over the TP. In spring, when larger SSD appears over the western TP, an anomalous cyclone occupies the northwestern TP, and the central and eastern TP lies between an anomalous cyclone and an anomalous anticyclone. There is an anomalous convergence (divergence) and ascending (descending) motion of airflows over the northwestern (central and eastern) TP. Concurrently, sufficient moisture occurs over the northwestern TP due to evaporation and atmospheric circulations. As a result, precipitation anomalously increases over the northwestern TP, and decreases over the central and southeastern TP. The SSD-related soil moisture anomalies over the western TP can persist into summer, and larger SSD corresponds to excessive summer soil moisture. The central and eastern TP lies between two anticyclones, leading to convergence of airflows and thereby ascending motions. Simultaneously, excessive moisture appears over the TP owing to atmospheric circulation transportation. Hence, precipitation anomalously increases over the central and eastern TP.