Multi-decadal Changes of the Impact of El Niño Events on Tibetan Plateau Summer Precipitation

Abstract

Precipitation on the Tibetan Plateau (TP) has an important effect on the water supply and demand of the downstream population. Involving recent climate change, the multi-decadal variations of the impact of El Niño-Southern Oscillation (ENSO) events on regional climate were observed. In this work, the authors investigated the changes in summer precipitation over TP during 1950–2019. At the multi-decadal scale, the authors found that the inhabiting impact of El Niño events on the TP summer precipitation has strengthened since the late 1970s. The main factor contributing to this phenomenon is the significant amplification in the decadal amplitude of El Niño during 1978–2019 accompanied by a discernible escalation in the frequency of El Niño events. This phenomenon induces anomalous perturbations in sea surface temperatures (SST) within the tropical Indo-Pacific region, consequently weakening the atmospheric vapor transport from the western Pacific to the TP. Additionally, conspicuous anomalies in subsidence motion are observed longitudinally and latitudinally across the TP which significantly contributes to a curtailed supply of atmospheric moisture. These results bear profound implications for the multi-decadal prediction of the TP climate.