01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-04-0165 |
| Title of Abstract | Observed Temperature Variability in the Abyssal Depths of the North Indian Oceanand its Dynamical Mechanisms. |
| Authors | Sumana Mandal*, Rohith B, Abhisek Chatterjee |
| Organisation | Indian National Centre for Ocean Information Services |
| Address | B-4 Incois quarter, pragatinagar Hyderabad, Telengana, India Pincode: 500090 E-mail: 08sumana@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | The temperature variability of the sea surface and the upper water column has been studied extensively over the last few decades owing to the availability of satellite observations and other in-situ measurements. However, our understanding of deep ocean temperature variabilities beyond the upper 2000 m remained limited owing to the lack of in-situ observations from the deeper parts of the ocean. This study investigates the deep ocean temperature variability in the north Indian Ocean using in-situ temperature observations during 2018-2022 at a depth of 2 km, 3 km, and 4 km in the Arabian Sea at 15°N, 68.8°E as part of the OMNI buoy network. At all these depths, distinct events of synchronised intraseasonal variability in the periodic band of 30-110 days are observed, albeit the energy decreases rapidly with depth. A similar events of intraseasonal temperature undulation is also observed in the in-situ bottom pressure recorders (BPRs) deployed in the northcentral Arabian Sea (20.80°N, 65.34°E) and in the southern Bay of Bengal (13.47°N, 88.99°E). This indicates that the abyssal depth of the north Indian Ocean experiences significant temperature variabilities, which remained completely undocumented till now. Lag-correlation analysis between the observed temperature at depths and altimeter data indicates that the signals originating in the central equatorial Indian Ocean propagate along the equator as high-order baroclinic modes of Kelvin waves and subsequently reflected Rossby waves cause the undulation in deeper isotherms. A specific property of these deeper undulations shows a large meridional scale extending until the northern limit of the BoB, but a very short zonal length scale of 200-300 km, indicating the influence of smaller lengthscale modes in the deeper part of the ocean. In conclusion, this study shows the interactions of deep ocean dynamics with upper oceanic processes and highlights the smaller correlation length scale in the deeper ocean. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Deep Ocean Variability, Iterseasonal Variability, Equtorial Forcing, Indian Ocean |
| For Awards | no |