Work

Trends and drivers of recent oxygenation in the Indian sector of the Southern Ocean

Year: 2026

Type: article

Abstract: Integrating in-situ observations from austral summers 2011 and 2025 with satellite and reanalysis data (1993–2025) reveals significant oxygenation across the Indian sector of the Southern Ocean (ISSO), with the strongest trends in the Polar (PZ) and Antarctic Zones (AZ). Observations along 57.5° E show elevated dissolved oxygen (DO), poleward retreat of the winter water (WW) layer, and partial shoaling of the oxygen minimum layer in 2025 relative to 2011. Combined effect of warming and salinification weakens stratification and promote circumpolar deep water (CDW) shoaling, driving enhanced ventilation and oxygenation. Declining apparent oxygen utilization is consistent with enhanced ventilation, not solubility changes, as the dominant mechanism. Oxygenation spans from Antarctic surface water and WW through subantarctic mode water, Antarctic intermediate water, and CDW to Antarctic bottom water, indicating basin-wide ventilation reorganization. These findings contrast with widespread global ocean deoxygenation and highlight the importance of Southern Ocean ventilation for the global ocean oxygen inventory.

Source: Environmental Research Letters

DOI: 10.1088/1748-9326/aeb70f