Influence of Scandinavian teleconnection pattern on summer precipitation over the eastern side of the Tibetan Plateau

This study analyses the relationship between the Scandinavian (SCA) teleconnection pattern and summer precipitation over the eastern side of the Tibetan Plateau (ESTP) between 1960 and 2020 and further studies the underlying physical mechanism. Statistical analysis showed that there is a significant and high negative correlation coefficient (around -0.59) between ESTP summer precipitation and the SCA teleconnection pattern over the period 1960-2020. When the SCA teleconnection pattern is in its negative phase, there is a significant increase in precipitation over most of the ESTP, and vice versa. Moisture budget analysis showed that vertical moisture advection makes a larger contribution to precipitation changes related to the SCA teleconnection pattern than evaporation and horizontal moisture advection. Specifically, positive precipitation anomalies related to the SCA teleconnection pattern are dominated by the enhanced dynamic component of vertical moisture advection, which is induced mainly by the significant ascending motion over almost the whole of the ESTP region. In summer, under the effect of the SCA teleconnection pattern, the abnormal westerly wind transports the mean warm air from TP to ESTP and forms an abnormal warm advection over the ESTP, resulting in a significant vertical upward motion and more summer precipitation over the ESTP. This study reveals the possible physical mechanism of the impacts of SCA teleconnection pattern on summer precipitation over the ESTP region and provides a scientific basis for ecological protection and disaster mitigation measures associated with major projects such as the Sichuan-Tibet railway and the Chengdu-Chongqing Economic Circle.