Remote tropical Western Indian ocean forcing on changes in june precipitation in South China and the Indochina Peninsula

Abstract

In this study, remote influence originating from the tropical western Indian Ocean on June precipitation in South China and the Indochina Peninsula is documented. Based on numerical simulation and statistical analysis, it is noted that the warm anomaly in the tropical western Indian Ocean can induce a weaker-thannormal Walker circulation across the tropical Indian Ocean and western Pacific Ocean. This further leads to a northeast-southwest-oriented western North Pacific subtropical high and a weaker-than-normal monsoon trough in the South China Sea. In addition, the weak monsoon trough is concurrent with an anomalous rising motion in South China and a sinking motion in the Indochina Peninsula. This enhances precipitation in South China and suppresses precipitation in the Indochina Peninsula on an interannual time scale. On the other hand, the warming trend in the tropical western Indian Ocean also supports the long-term trends of precipitation in the two regions.