01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-02-0068 |
| Title of Abstract | Defining the SCTR depth in the Southwestern Tropical Indian Ocean: Review and Revisit |
| Authors | Chan Joo Jang*, Heeseok Jeong, Fuad Azminuddin, Saat Mubarrok, Suyun Noh, Dong-Jin Kang |
| Organisation | Korea Institute of Ocean Science and Technology |
| Address | 385 Haeyang-ro, Youngdo-gu Busan, Kyoungsangnamdo, Korea, Rep. Pincode: 49111 E-mail: cjjang@kiost.ac.kr |
| Country | Korea, Rep. |
| Presentation | Oral |
| Abstract | The 20 °C isotherm depth (D20) has been commonly used to represent the SCTR depth in the southwestern tropical Indian Ocean, mainly because of its simplicity and insufficient vertical resolution in both observation and modeling. Although D20 has been widely used, D20 does not always align with the physical thermocline defined as the maximum vertical temperature gradient. This discrepancy can lead to inaccuracies in understanding air-sea interaction dynamics and climate variability. In this study, we examine how well D20 and its variability are matched with those of the thermocline in the SCTR, by using CTD data obtained from six cruises of the RV ISABU from 2017 to 2023, as part of the project titled ⿿Korea Indian Ocean Study (KIOS), and reanalysis data (Global Ocean Reanalysis and Simulation Version 4 (GLORYS2V4) and Simple Ocean Data Assimilation version 3.15.2 (SODA3.15.2)). Sixteen CMIP6 model outputs were analyzed to determine future changes in the D20 and thermocline depth in the SCTR. We found that in the SCTR, D20 is generally deeper than the depth of the maximum vertical temperature gradient (Dtc). Dtc appears to be more aligned with the depth of the 24 °C or 25 °C isotherm. Future changes projected by CMIP5 models reveal that D20 tends to deepen in most of the tropical Indian Ocean at the end of the 21st century. In contrast, changes in thermocline depth (Dtc) show a spatially contrasting pattern in the tropics: shallowing in the eastern tropical Indian Ocean and deepening in the western tropical Indian Ocean, including the SCTR region. |
| Are you part of IIOE-2 endorsed project | yes |
| Endorsed Project Number | IIOE2-EP31 |
| Keywords | SCTR, Indican Ocean, thermocline depth, revisit |
| For Awards | no |