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Intraseasonal response of the northern Indian Ocean coastal waveguide to the Madden-Julian Oscillation

Vialard, J and Shenoi, SSC and McCreary, JP and Shankar, D and Durand, F and Fernando, V and Shetye, SR (2009) Intraseasonal response of the northern Indian Ocean coastal waveguide to the Madden-Julian Oscillation. Geophysical Research Letters, 36 (14).

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Abstract

A new observational record of upper-ocean currents at 15°N on the western coast of India is dominated by intraseasonal (55-110 day) variations of alongshore currents, whereas sea level at the same location has a clear seasonal signal. These observations can be interpreted within the framework of linear wave theory. At 15°N, the minimum period for planetary waves is ~90 day, meaning that intraseasonal energy is largely trapped at the coast in the form of poleward-propagating Kelvin waves, while lower-frequency signals associated with the annual cycle can radiate offshore as planetary waves. This dynamical difference results in a steeper offshore slope of sea level at intraseasonal timescale, and thus stronger geostrophic alongshore currents. A consequence is that the alongshore currents are in-phase with intraseasonally-filtered sea level near the coast, and a gridded satellite product is shown to reproduce the current variations reasonably well. The intraseasonal current variations along the west coast of India are part of basin-scale sea-level fluctuations of the Northern Indian Ocean equatorial and coastal waveguides. The wind forcing associated with this basin scale circulation closely matches surface wind signals associated with the Madden-Julian Oscillation Copyright 2009 by the American Geophysical Union.

Item Type: Article
Additional Information: Copyright of this article belongs to American Geophysical Union.
Subjects: Oceanography > oceanography
Depositing User: INCOIS Library
Date Deposited: 21 Nov 2013 10:32
Last Modified: 21 Nov 2013 10:32
URI: http://moeseprints.incois.gov.in/id/eprint/213

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