01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-04-0077 |
| Title of Abstract | Reduced Ventilation of Southeast Indian Ocean Water Masses revealed by Repeat Hydrography Along 110°E (1963-2019) |
| Authors | Meng Han, Helen Phillips *, Nathan Bindoff, Ming Feng, Ram Patel |
| Organisation | University of Tasmania |
| Address | 20 Castray Esplanade Battery Point, TAS, Australia Pincode: 7005 E-mail: h.e.phillips@utas.edu.au |
| Country | Australia |
| Presentation | Oral |
| Abstract | The South Indian Ocean (SIO) plays a critical role in global climate through its contribution to the global meridional overturning circulation. Two repeat full-depth hydrographic sections along 110°E (1963 vs. 2019) reveal substantial changes in Subtropical Water (STW), Subantarctic Mode Water (SAMW), and Antarctic Intermediate Water (AAIW)⿿key watermasses in the upper cell of the overturning circulation⿿over 56 years. STW has warmed and become saltier along isopycnals, while SAMW and upper AAIW have cooled and freshened, primarily through spice (along-isopycnal) changes, pointing to salinity-driven processes from their source regions. In contrast, lower AAIW shows warming and salinification, suggesting temperature-driven variability. The thickening of SAMW and AAIW layers, combined with increased apparent oxygen utilization (AOU), nitrate, and phosphate, indicates reduced ventilation and potential circulation changes. These property shifts imply a slowdown in overturning circulation and altered nutrient cycling, consistent with anthropogenic climate change impacts. |
| Are you part of IIOE-2 endorsed project | yes |
| Endorsed Project Number | IIOE2-EP06 |
| Keywords | overturning circulation, watermass change, ventilation, nutrients, hydrographic data, climate change impacts |
| For Awards | no |