Effect of thermal conditions over the Arabian Sea-Iranian Plateau on the climate of the East Asian monsoon region

Owing to the considerable socioeconomic impact of summer precipitation over East Asia (SPEA), its study is of great interest to the scientific community. The impact of the Tibetan Plateau on SPEA has been studied extensively; however, the impact on SPEA of the neighboring Iranian Plateau, a geographically analogous uplift with distinct thermal characteristics, remains poorly understood. This study explored how the thermal conditions over the Arabian Sea and the Iranian Plateau affect the climate of the downstream region of East Asia. Results showed that in-phase temperature variations over the Arabian Sea and Iranian Plateau intensify precipitation over both northern and southern China. Additionally, the thermal contrast between the Arabian Sea and the Iranian Plateau can lead to a strong (weak) meridional thermal gradient (MTG), leading to a cyclonic (anticyclonic) anomaly over the Iranian Plateau. This anticyclonic (cyclonic) circulation anomaly generates a midlatitude wave train that propagates eastward, which induces negative (positive) and positive (negative) precipitation anomalies over South China and the Northwest Pacific, respectively. Furthermore, we also found that this MTG anomaly is strongly related to preceding spring El Niño-Southern Oscillation events and spring-summer Indian Ocean Basin Mode events. In elucidating this air-sea interaction mechanism, our study provides a potential predictor for improved seasonal forecasting of SPEA.