Tuesday 23 August 2005

GP2

PT0085
Zonal variations of sea level over Indian Ocean using altimeter data
Devasena, Chikka Kalyani¹
1 C-MMACS (Centre For Mathematical Modeling And Computer Simulation), India
Author email: kalyani@cmmacs.ernet.in
Sea level variations have an impact on the underlying water layers. The upper few tens of meters in the ocean directly respond to varying wind system. Heat transfer in this layer can be directly related to the sea level variations caused by wind. So the sea level fluctuations are helpful in the studies of oceanic processes. Here an attempt has been made to study the zonal average of sea level over the Indian Ocean in every alternate 1 deg latitude bands extending across the full width of the study area (45-100E longitude and 20s-20n latitude), derived from merged altimeter data. In general all the latitudinal belts experience either two maxima and one minimum or one maximum and two minima showing the bimodal oscillations in the sea surface height changes in the Indian Ocean primarily influenced by the changing monsoonal winds. The amplitude of the oscillation is minimal at the southern latitudes and more in the northern latitudes. The northern Indian Ocean, particularly in the 20 deg N latitudinal belt is land locked in both the Arabian Sea and the Bay of Bengal. Any movement of water is restricted by the surrounding land portion and the sea level increases, hence more oscillations are seen at this region. Moreover, the changes in sea surface height are less during a week monsoon year (ex 1987 compared to a strong monsoon year (ex 1988, 1994) indicates the influence of the monsoonal winds in the sea surface height changes particularly in the northern latitudes. The sea level variations are less in southern hemisphere (20 deg S latitude -Equator) and more in the northern hemisphere (Equator-20 deg N latitude). Further, high sea level is observed in a good monsoon compared to a bad monsoon year. Zonal sea level studies help in understanding the meridional water movements.

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