Temporal variation of particle flux in the Seychelles–Chagos Thermocline Ridge region of the western Indian Ocean (2022–2024): Links to the Indian Ocean Dipole and El Niño–Southern Oscillation

Abstract The Seychelles–Chagos Thermocline Ridge is an upwelling region in the western Indian Ocean, but its role in sinking particle flux remains unclear. We present sediment trap records (July 2022 to June 2024) at 1000 and 2500 m to reveal variations in particle flux and composition. During the first period (July 2022 to June 2023), particulate organic carbon (POC) fluxes, accompanied by CaCO 3 and biogenic opal peaks, reached 6.7 mg m −2 d −1 and were linked to negative‐to‐positive transitions of the Indian Ocean Dipole (IOD) and El Niño–Southern Oscillation that enhanced upwelling and nutrient supply. The ballasting effect increased transfer efficiency further during these high‐flux events. Conversely, during the second period (July 2023 to June 2024), under positive IOD and ENSO phases and with reduced CaCO 3 and biogenic opal fluxes, POC fluxes declined sharply. These findings highlight the combined influence of climate variability and mineral ballasting on the carbon cycle.