Summer precipitation anomalies in the low-latitude highlands of China coupled with the subtropical Indian Ocean dipole-like sea surface temperature

Abstract

The relationship between the subtropical Indian Ocean dipole (SIOD)-like sea surface temperature (SST) and summer precipitation in the low-latitude highlands (LLH) of China is investigated in a suite of numerical simulations using an atmospheric general circulation model (AGCM) and a coupled ocean–atmosphere model. The AGCM experiments driven by SIOD-like SST anomalies are inconsistent with the observations. However, the coupled ocean–atmosphere experiments show a good agreement with the observational results. The modeling results indicate that the air–sea interaction rather than a simple atmospheric forcing–response relationship is a crucial mechanism explaining the connection among the anomalous summer precipitation in the LLH, the anomalous divergence circulations across the Indian Ocean, and the SIOD-like SST anomalies. The effect of the enhanced interhemispheric vertical circulation variability associated with the SIOD-like SST anomalies facilitates zonal wind anomalies in the northern Bay of Bengal, and further induces anomalous water vapor convergence and precipitation anomalies in the LLH. The SST–wind–evaporation feedback mechanism could account for maintenance of the SIOD-like pattern in the coupled ocean–atmosphere experiments. These results could help to improve prediction accuracy of summer rainfall variations over the LLH of China.