01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-04-0084 |
| Title of Abstract | Southern Indian Ocean Warming Accelerated by Shifts in Inter-Basin Heat Transport |
| Authors | SAJIDH CK, Abhisek Chatterjee*, Raghu Murtugudde, Michael J McPhaden, S S C Shenoi, P N Vinayachandran |
| Organisation | Indian National Centre for Ocean Information Services |
| Address | IIT madras Hyderabad, Tamil Nadu, India Pincode: 600036 E-mail: sajidh.c.k@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | The Indian Ocean has experienced rapid warming over recent decades, though this warming has been spatially non-uniform. Notably, the Southern Indian Ocean (SIO; 5°S⿿35°S) cooled until the late 20th century before undergoing an abrupt warming. Previous studies attributed this recent warming primarily to increased Indonesian Throughflow (ITF) during the global surface warming hiatus (1998⿿2010). Our analysis, however, reveals that despite a strong decadal variability and a declining ITF trend over the past decade, the SIO upper ocean has continued to accumulate heat at a rate of 0.65 (±0.02) ÿ 10²² J/decade. We propose that the enhanced ITF during the hiatus initiated the SIO warming, which in turn weakened the Mascarene High and decoupled it from Southern Ocean atmospheric variability. This led to an asymmetric poleward shift of the subtropical gyres between the Indian and Pacific Oceans, allowing increased Tasman inflow to compensate for the weakened ITF in recent years. The resulting heat accumulation in the SIO further weakened the Mascarene High and reduced the Agulhas outflow by approximately 3 Sv/decade, reinforcing a positive feedback loop that sustained the warming of the upper SIO. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Indian Ocean warming, Sub-surface heat content, Indonesian throughflow, Tasman leakage |
| For Awards | no |