Relationship between the Tibetan Plateau Heat Source and Convection over the Philippine Sea

Based on various datasets, the relationship and its relevant mechanism between the Tibetan Plateau heating (TPH) and convection over the Philippine Sea (CPS) in August are studied. It is found that the circulation pattern associated with TPH in the summer should be discussed on a monthly basis since the atmospheric circulation pattern varies significantly in the summer. The result indicates that TPH in August is significantly and negatively correlated with CPS. The coupled circulation systems, including the western North Pacific subtropical high (WNPSH), the monsoon low over Indian, the South Asia High, westerlies and the western North Pacific monsoon, all contribute to the anti-correlation between TPH and CPS in August. The processes are as follows. Due to strong (weak) CPS accompanied by southwestward (northeastward) movement of the WNPSH, monsoon circulations over western North Pacific and Indian both weaken (intensify), which leads to a strong (weak) water vapor flux on the western flank of the WNPSH and the equatorward (poleward) shift of westerlies. A strong South Asia High subsequently appears in the upper level. As a result, rainfall over the southern Tibetan Plateau becomes higher (lower) than normal, leading to strong TPH. After that, the southwesterly (northeasterly) anomalies caused by TPH anomalies emerge, leading to southwestward (northeastward) shift of the WNPSH and contributing to strong (weak) CPS. Furthermore, the above mechanism works in both strong and weak TPH events, and works better in strong TPH years. This mechanism can also be found in certain cases, indicating a strong interaction between TPH and CPS in August.