Inter-annual variability of spring precipitation over the Indo-China Peninsula and its asymmetric relationship with El Niño-Southern Oscillation

Previous studies suggested that the dry–wet surface state over the Indo-China Peninsula (ICP), closely associated with the local spring precipitation, is an important seasonal predictor for the East Asian summer monsoon and extreme climate. Hence, this work investigates the inter-annual variability of spring precipitation over the ICP and its relationship with El Niño-Southern Oscillation (ENSO) during 1958–2019. The results show that the spring precipitation anomalies over the ICP are highly linked to the ENSO-induced atmospheric circulation anomalies. In particular, there are large asymmetries in the precipitation anomalies for the spring following ENSO. During the decaying spring of the El Niño events, the precipitation decrease mainly occurs over the Western ICP associated with an anomalous low-level anticyclone over the western North Pacific. In contrast, during the decaying spring of the La Niña events, a stronger precipitation increase broadly extends into the Southeastern ICP. This is owing to a nonlinear effect of ENSO on the atmospheric circulation. Compared to El Niño, the abnormal center of La Niña extends too far westwards, inducing a westward movement of the anomalous atmospheric circulation, which results in a stronger effect on the spring ICP precipitation. Our findings emphasize the nonlinear responses of the spring ICP precipitation to ENSO. This has important implications for the seasonal climate prediction over the ICP, especially for the Southeastern ICP countries/regions.