Early and Late Summer Relationships between the Silk Road Pattern and the Precipitation Variation Surrounding the Northern Tibetan Plateau

Abstract The Silk Road pattern (SRP) is an important summer teleconnection pattern across the midlatitude Eurasia and is featured by alternate southerly and northerly wind anomalies along the upper-tropospheric westerly jet. It affects significantly the boreal summer climate, including those around the Tibetan Plateau (TP), which has been investigated much based on the summer mean results. However, the SRP shows substantial differences between early and late summer, which are separated at early July. This study identifies that the SRP’s impacts on precipitation surrounding the TP differ much between the two periods: The SRP-related precipitation anomalies are significant over the northeastern TP (NETP) in early summer, but shift northwestwards to domains around the northwestern TP (NWTP) in late summer. These differences can be attributed to the subseasonal change of the SRP and its configurations with the thermal condition surrounding the TP. The SRP is located more westward in late summer than in early summer. Correspondingly, the SRP-related southerly anomalies around the TP prevail over the NETP in early summer but over the NWTP in late summer. Superimposed onto the climatological thermal contrast between the humid southern TP and the dry north, these southerly anomalies favor the northward moisture transport and local precipitation genesis. NETP and NWTP are two domains with greater precipitation amount surrounding the northern TP and are crucial for the Asian ecological and environmental balance. Therefore, the present study holds practical implications for enhancing the accuracy of summer precipitation forecasts surrounding the TP on a subseasonal time scale and further improves regional climate adaptation and water resource management.