- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
Abstract Submission No. | ABS-2022-03-0401 |
Title of Abstract | Fate of Arabian Sea high-salinity core after the intrusion of low salinity water mass |
Authors | Anoop T R*, Subeesh M P, Teesha Mathew, Glejin Johnson, Sheela L Nair, Sreejith N, Sameer V K, Jubin K Thomas, Prasad R, Anil Kumar N |
Organisation | National Centre for Earth Science Studies |
Address | Project Scientist B, MGG, National Centre for Earth Science Studies (NCESS) Thiruvananthapuram, Kerala, India Pincode: 695011 Mobile: 9447417422 E-mail: anooptr43@gmail.com |
Country | India |
Presentation | Oral |
Abstract | The subsurface high salinity core (HSC) is a climatological feature in the eastern Arabian Sea (EAS). The formation and erosion of HSC is critical in determining the upper water column stability and the heat distribution in this region. We utilised spatial and time series hydrographic observations obtained from a cruise during the period 4 April to 4 May 2021 together with numerical model simulations to understand the evolution of HSC in the EAS. Spatial hydrographic survey reveals the presence of HSC at a depth range of 70-140 m in outer shelf and deeper region with upwelling signature towards the coast. It is observed that the HSC bifurcates at around 100m depth from 26 April and reforms in the first week of May. Intrusion of a low salinity water mass associated with the strong northward current is found to be the primary mechanism behind this bifurcation. The bottom part of HSC is detached by this intruded water and starts to sink as a water parcel. This parcel is clearly distinguishable from the ambient water by its comparatively higher salinity. While sinking, the parcel loses its temperature at the rate of ~1°C/day and it reaches its neutral buoyancy at ~200 m water depth from 28 April onwards. Numerical simulations using a high-resolution (~1 km) Regional Ocean Modelling System (ROMS) for eastern Arabian Sea shows that the HSC is maintained by equatorward current associated with an anticyclonic eddy during the observation period. During the disruption of the HSC, the low saline subsurface water mass driven by a strong northward current displaces this eddy westward. The weakening of this current allows the eddy to return back, leading to the reformation of the HSC. The experimental simulation with reduced current magnitude from the southern boundary failed to reproduce the observed disruption associated with the movement of eddy. Our study shows that the temporal evolution of the HSC in the EAS is largely determined by the position and movement of the eddy in the region in combination with the advection of water mass from the south. |