Presenter: Yadidya Badarvada (Indian Institute of Technology Delhi)

Description:
The Andaman Sea is a marginal sea in the northern Indian Ocean where one of the world’s strongest internal wave activity is observed. The density stratification from Ocean Reanalysis System 5 during 1993-2018 is used as a proxy for investigating the interannual variability of internal waves. The depth-averaged (0-300 m) annual cycle of buoyancy frequency displayed a bimodal structure with peaks in Spring and Autumn. Earlier studies suggested that the mean coastal circulation within the Andaman Sea is primarily influenced by the remote equatorial forcing. A good correlation is observed during Autumn between the depth-averaged buoyancy anomaly and the Dipole Mode Index which represents the Indian Ocean Dipole (IOD). Moreover, the stratification has significantly increased (decreased) during positive IOD (negative IOD) in Autumn. Furthermore, numerical simulations using 3D MITgcm are carried out from 2009 to 2018. They are validated with in-situ observations at BD12 and RAMA buoy along with tidal-gauge data at Port Blair, Moulmein, Ko Taphao Noi, and Sabang. The generation and dissipation of internal tides showed significant variability along the Andaman Nicobar Ridge. Idealized experiments with homogenous stratification revealed the effect of IOD on interannual variability in the internal tide energetics.