在ENSO不同位相下青藏高原春季感热对华南盛夏降水的影响

根据青藏高原(简称高原)春季感热(Sensible Heat,SH)异常和ENSO不同位相,划分出12种类型,研究了高原春季(5月)SH异常和前冬ENSO对华南盛夏(7—8月)降水的影响及相对影响程度。结果表明:高原春季SH和前冬ENSO均对华南盛夏降水有较显著的影响,即当两者分别处于各自正(负)位相时,华南盛夏降水普遍偏少(多);通过对两者的单独作用和协同作用的分析表明,高原春季SH对华南盛夏降水贡献要更大。影响机制分析发现华南盛夏降水受西太平洋副热带高压(简称西太副高)和南亚高压共同影响,ENSO直接影响西太副高,而高原春季SH异常则对南亚高压作用显著,因此在两者共同影响下,两个高压的变化共同导致华南盛夏降水出现异常。

EFFECTS OF SPRING SENSIBLE HEAT IN THE TIBETAN PLATEAU ON MIDSUMMER PRECIPITATION IN SOUTH CHINA UNDER ENSO

This paper categorized 12 types of Sensible Heat (SH) and ENSO abnormal phases in the Tibetan plateau (plateau for short) and studied the influence and relative importance of ENSO and SH in spring (May) on midsummer (July-August) precipitation in south China. The main conclusions are as follows: both SH and ENSO have significant influence on the south China midsummer precipitation. When the two are in their respective positive (negative) phases, the south China midsummer precipitation is generally less (more). The independent and synergistic effects of the two indicate that the relative contribution of plateau SH to the south China midsummer precipitation is larger. The analysis of the influence mechanism shows that the midsummer precipitation in south China is affected by the subtropical high in the western Pacific and the south Asian high. ENSO directly affects the western Pacific subtropical high, while the spring SH anomaly in the plateau has a significant effect on the south Asian high. Therefore, under the combined influence of the two, the changes of the two high pressures jointly lead to the abnormal summer precipitation in south China.