Arabian Sea Variability During Indian Ocean Tripole Events

The dynamics of the Tropical Indian Ocean (TIO) are strongly influenced by climate modes linked to Sea Surface Temperature Anomalies (SSTA). Among these, the Indian Ocean Tripole (IOT), the third interannual mode of SSTA variability, is characterized by positive (negative) SSTA in the central (eastern and western) region of the TIO. IOT is distinct from Indian Ocean Dipole (IOD) particularly over the Arabian Sea showing significant negative SSTA in the region during its positive phase. This study focuses on the impacts of IOT mode over the Arabian Sea and adjacent regions. Our findings indicate that negative SSTA over the region are associated with unique wind patterns during the peak season from June to August (JJA), promoting major upwelling along the western coast, advecting warm waters towards the south-eastern region. The resulting negative SSTA reduces evaporation, leading to changes in heat transfer from ocean to atmosphere. Positive IOD events are associated with a decline in precipitation over the western coast of the Arabian Sea, including the regions of Oman, Yemen, and Somali, with the most notable decline occurring in the southern region of Yemen. In contrast, the northern, central, and south-central, along with the western coast of India experience a significant increase in precipitation, while the southern region shows a decreasing trend. These patterns reverse during a negative IOT event. This study highlights the crucial role of the IOT for improving monsoon and seasonal forecasting over the region.