Interdecadal variation of Indian Ocean basin mode and the impact on Asian summer climate

This study documents an interdecadal variation in the pattern of Indian Ocean basin mode (IOBM) of sea surface temperature (SST) during boreal summer, where the center of action in the IOBM shifted towards the Arabian Sea after the late 1970s. Correspondingly, the influences of an interannual warming in the tropical Indian Ocean on the Asian summer climate became more significant after the late 1970s due to the Arabian Sea center of action, which are characterized by anomalous subsidence and anticyclones over the Bay of Bengal and the South China Sea. These atmospheric anomalies may result in surface temperature and precipitation anomalies in a wide area of Asia. Numerical experiments demonstrate the different influences of different IOBM patterns on the Asian summer climate. Statistical analysis and numerical experiments indicate a minor role of the different tropical Pacific SSTs concurrent with the different IOBMs in causing the different Asian summer climate anomalies.