The Indian Ocean Tripole (IOT), identified as the third EOF mode of Sea Surface Temperature Anomalies (SSTA), exhibited significant variability during its positive and negative phases in 2018 and 2009, respectively. In 2018, positive SSTA exceeding 0.25 \(\:^\circ\:\) C/month dominated the south-central Tropical Indian Ocean (TIO), while the western and eastern TIO experienced negative anomalies of approximately − 0.5 \(\:^\circ\:\) C/month and − 0.12 \(\:^\circ\:\) C/month, respectively. Conversely, in 2009, the south-central TIO was characterized by negative SSTA of -0.1 \(\:^\circ\:\) C/month, whereas the western and eastern regions recorded positive anomalies of 0.41 \(\:^\circ\:\) C/month and 0.34 \(\:^\circ\:\) C/month, respectively. A defining feature of these events was the strong contrast in anomalies, particularly in the western region. During the JJA season of 2018, anomalous wind speeds of up to 0.52 m/s strengthened ocean currents in the Somali upwelling region by 0.43 m/s. In contrast, the speeds of wind and ocean current decreased by 1.1 m/s and 0.27 m/s, respectively, in 2009. The intensified monsoon currents during IOT events were associated with the pressure gradient between the low-pressure zone over the Thar Desert and the Mascarene High, driven by anomalous warming over northern India. In 2018, this warming intensified the monsoon trough, strengthening monsoon winds over the Somali upwelling region. These enhanced winds increased wind stress on the ocean surface, leading to stronger Ekman pumping. This mechanism facilitated higher upwelling; bringing cooler, nutrient-rich waters to the surface and contributing to the observed negative SSTA in the western TIO. Upwelling along the Somali coast was further supported by the shallowing of the 20 °C isotherm, reinforcing negative SSTA in the western region. However, in 2009, despite warming over northern India, the presence of strong positive SST anomalies over the region led to the contrasting conditions, suppressing upwelling. This study enhances our understanding of TIO dynamics during positive IOT events and their broader climatic impacts.
