OS51A-1972
On the importance of Sri Lanka for sea-level variability along the west coast of India

Friday, 18 December 2015
Poster Hall (Moscone South)
Iyyappan Suresh1, Jérôme Vialard2, Takeshi Izumo3, Matthieu Lengaigne2, Weiqing Han4, Julian P McCreary Jr5 and Muraleedharan Pillathu Moolayil1, (1)National Institute of Oceanography, Panjim, India, (2)LOCEAN, Paris, France, (3)LOCEAN-IPSL, Paris cedex 05, France, (4)Univ of Colorado, Boulder, CO, United States, (5)University of Hawaii at Manoa, Honolulu, HI, United States
Abstract:
Earlier studies have illustrated the strong influence of remote forcing from the equator and the Bay of Bengal on the sea-level variability off the west coast of India, especially at the seasonal timescale. More recently, Suresh et al. [2013] demonstrated with a simple, linear, continuously-stratified (LCS) model that the equatorial zonal winds contribute to more than 60% of intraseasonal sea-level variability along the Indian west coast. In the present study, we quantify the contributions from various processes to the sea-level variability along the west coast of India at different timescales with the help of a LCS model through both idealized and realistic sensitivity experiments. We demonstrate that remote forcing dominates the sea-level variability along the west coast of India at intraseasonal to interannual timescales. Sri Lanka and the southern tip of India play an important role on Indian west coast sea-level variability at all timescales for two reasons: First, the geometry of the coast favors a strong alongshore wind-stress forcing of coastal Kelvin waves across timescales there. Second, Sri Lanka interacts with low-order meridional mode equatorial Rossby waves forced by equatorial winds or southern Bay of Bengal wind- stress curl. This interaction of coastal waveguide with equatorial waveguide creates a new pathway for the equatorial signals to arrive at the west coast of India, alternative to the “classical” coastal waveguide around the rim of the Bay of Bengal.

Reference:

Suresh, I., J. Vialard, M. Lengaigne, W. Han, J. McCreary, F. Durand, and P. M. Muraleedharan (2013), Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide, Geophys. Res. Lett., 40, 5740–5744, doi:10.1002/2013GL058312.