Active Role of the Southeast Asian Monsoon in Selective Monsoon–ENSO Interaction

The interactive nature of the Asian monsoon and ENSO has been investigated extensively; however, many aspects of the selective monsoon-ENSO interaction (Webster and Yang 1992) still remain unclear. This study indicates that considering the annual cycles of both monsoon and ENSO is important for understanding monsoon-ENSO interaction and uncovering the unique features of monsoon-ENSO interaction in springtime is critical for understanding the interaction between monsoon and ENSO especially it selectively-interactive features. In the past decades the atmospheric heating and sea surface temperature in Southeast Asia and adjacent regions have increased apparently, especially in the spring season, and these increases have caused significant changes in global climate and ENSO evolution. For example, the convection over Southeast Asia in spring causes changes in the evolution of the Pacific trade wind and thus the Walker circulation and ENSO in the subsequent seasons e.g. from summer to winter. The favorable role of the Maritime Continent (land) in the decay of ENSO from winter to the next spring will also be discussed, along with the physical mechanisms for the influence of the Maritime Continent on ENSO intensity and frequency.