The Indian Ocean Surface Salinity during El Nio

El Nio (EN) is a critical air-sea interaction that occurs between the atmosphere and the ocean in the tropical eastern Pacific region. Previous studies have classified EN into two main types: the traditional EN and the central Pacific EN. This research uncovers that these EN have substantial impacts on the annual variations in ocean salinity in the equatorial Indian Ocean, particularly during the autumn season in the Northern Hemisphere. During traditional EN, ocean salinity tends to decrease, whereas during central Pacific EN, it increases. A thorough salinity budget analysis was conducted to determine the key drivers influencing changes in Indian Ocean salinity. The results suggest that wind-induced anomalous zonal advection plays a crucial role in these salinity changes, which are further affected by the abnormal zonal circulation patterns across the Indian Ocean.