第九届青年地学论坛

The study investigated the impacts of snow cover extent (SCE) over the Tibetan Plateau (TP) on the interannual variation in spring precipitation over the Tarim Basin (TB) (SPTB) for the period 1980-2019. Significant anomalies in westerly winds, associated with a low–pressure anomaly in the northern TB and a high–pressure anomaly in the southwestern TB, enhance moisture conveyance from upstream areas to the TB, thereby promoting increased SPTB. The analysis shows that anomalous SCE over the northwestern and central-western TP, which persists from winter to spring, has a close relationship to SPTB variation. A localized energy budget analysis reveals that increased winter TP SCE induces cooling effect to the overlying atmosphere, resulting in an abnormal low-pressure system prevailing over the troposphere above the western TP. This anomalous low-pressure system can persist into the subsequent spring due to the local snow-atmosphere feedback effects. Furthermore, the persistence of the low-pressure system is facilitated by energy conversion from the background flow. This TP SCE-related low pressure is accompanied by upward motion and moisture convergence over the TB, ultimately enhancing the SPTB. Further analysis indicates that anomalous warming of sea surface temperature (SST) in Indian Ocean during winter leads to the intensification of the subtropical high. This intensification facilitates the uplifting and transporting warm moisture from lower–latitude oceans to middle latitudes, consequently contributing to the increased TP SCE and SPTB. Thus, a multifaceted mechanism of ocean-land-atmosphere interaction emerges, encompassing Indian Ocean SST, TP snow, and atmosphere circulation. Importantly, the impact of TP SCE on SPTB is primarily independent of anomalous Indian Ocean SST in northern TB.