Relationship between Tropical Indian Ocean SSTA in Spring and Precipitation of Northeast China in Late Summer

Sea surface temperature anomaly (SSTA) is a major signal for prediction of summer precipitation in East Asia. The relationship between SSTA in the tropical oceans and summer precipitation in East Asia has been documented in many studies. However, the relationship between SSTA and late summer (July–August) precipitation (JAP) over Northeast China (NEC) on the interannual timescale has received little attention. In this study, we examine the relationship between Indian Ocean Basin warming (IOBW) anomalies in spring and the JAP in NEC since the early 1960s. A significant positive correlation is found between the spring IOBW index and JAP over NEC. The positive spring IOBW anomaly is followed by an anomalous anticyclone from Northwest Pacific to the Korean Peninsula. This anomalous anticyclone favors a significantly strong and northward western Pacific subtropical high (WPSH), which facilitates anomalous southerly winds over NEC and the transport of more water vapor into this region. Further analysis indicates that the spring IOBW anomalies have important impacts on the vertical air motion in the tropics and subtropics during the summer. Significant anomalous upward (downward) motion covering Indonesia (Northwest Pacific to the southern Korean Peninsula) occurs when the IOBW is in its positive phase, which favors the northward movement of the WPSH in late summer and more precipitation over NEC in July–August. Modulation of the atmospheric circulation by this mechanism further influences the JAP over NEC.