盛夏青藏高原热源与菲律宾海对流活动的联系

通过多源资料诊断分析，本文讨论了盛夏（8月）青藏高原大气热源与菲律宾海对流活动之间的联系及可能的机制。结果表明，与青藏高原热源相联系的环流形势在夏季各月明显不同，因此对夏季青藏高原热源的影响应当分月讨论。在夏季各月中，菲律宾海对流活动与青藏高原热源在8月份的联系最为紧密，二者存在显著的反相关关系。而8月青藏高原热源、菲律宾对流活动、西太平洋副热带高压（简称西太副高）、印度季风低压、南亚高压、西风带槽脊和西北太平洋季风环流存在相互耦合的过程。青藏高原热源与菲律宾海对流活动之间联系的机制为:菲律宾海对流弱（强）年，西太副高偏西（东）偏南（北），西北太平洋季风环流减弱（加强），印度季风低压减弱（加强），西风带南压（北抬），又加之副高西侧有强（弱）的水汽输入，兼以高层南亚高压加强（减弱），使得高原南部降水显著增强（减弱），高原热源整体加强（减弱），高原热源的加强（减弱）又造成了高原南部到东亚区域低层西南（东北）风异常，又利于西太副高偏西（东）偏南（北），从而造成菲律宾海对流减弱（加强）。这一机制在高原热源强弱年均有表现，但强年表现得更为显著，并在个例中也有所体现，说明盛夏青藏高原热源异常和菲律宾海对流异常存在显著的相互作用。

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.