The interdecadal changes in the pattern of summer precipitation over the Tibetan Plateau around the mid-1990s

<p>The interdecadal changes in the pattern of the summer precipitation over the Tibetan Plateau (TP) are studied around the mid-1990s. During 1961-1996, the dominant mode of the interannual variations of summer precipitation over the central-eastern TP is shown a dipole pattern, with opposite variation between the southeastern and northeastern TP. While during 1997-2019, the dominant mode become a mono-sign pattern. During 1961-1996, the dipole pattern of TP precipitation is essentially driven by the North Atlantic Oscillation (NAO) and the related circulation anomalies. However, the impact of NAO on the TP precipitation has weakened since the mid-1990s. In contrast, more intensified positive height anomalies in the upper troposphere are observed over the whole TP regions during 1997-2019. Meanwhile, the southerly moisture flux from the Bay of Bengal and the Philippine Sea is prevalent significantly with strong moisture convergence. This interdecadal spatial shift is mainly attributed to the significant increasing of the sea surface temperature (SST) in the Atlantic Ocean and Indo-Pacific warming pool. The warming SST could induce Rossby waves and propagate to TP regions. The wave train-related positive height anomalies are in favor for the strengthening of the South Asian high (SAH). Moreover, the SAH-related circulation anomalies are primarily responsible for the intense vertical flow anomalies in the TP. As a result, the summer precipitation anomalies over the entire TP regions are largely increased and formed the mono-sign pattern during 1997-2019. Based on the Coupled Intercomparison Project Phase 6 models projection results, further analysis demonstrates that the dominant pattern of summer precipitation in south and north TP shows robustly consistent variation during the center and end of the 21^st century, and would become more pronounced under higher scenario. These findings indicate the significant future transformation of TP precipitation pattern and atmospheric circulations in response to greenhouse warming.</p>