A study of the Indian Ocean circulation using satellite observations and model simulations
A study of the Indian Ocean circulation using satellite observations and model simulations
The Indian Ocean circulation is studied using remotely-sensed satellite observations of sea surface height, sea surface temperature and surface winds to gain a more complete view of the surface circulation than is possible from hydrographic studies alone. The instruments used are, respectively, TOPEX/POSEIDON (T/P) altimeter, ERS-1 Along-Track Scanning Radiometer (ATSR) and Scatterometer during 1993-1995.
The Somali eddies and possible formation mechanisms in the Arabian Sea are studied. The most energetic eddies found along the Somali coast depend on the monsoon system. The western boundary current, East India Coastal Current (EICC), in the Bay of Bengal is detected and analysed. Because of the scarcity of measured data in this region, satellite observations are required to examine the mechanisms which are involved in driving the EICC. Kelvin waves and Rossby waves in the Indian Ocean are identified and their role in energy transfer to the western boundary currents and to the eddies is examined. Kelvin and Rossby wave phase speeds are computed using two dimensional Fast Fourier Transforms (FFT) and Complex Principal Component (CPCA) Analysis. The phase speeds calculated from T/P altimetric observations are comparable to recent work by Killworth et al. (1997).
A simple isopycnic N-layer wind-driven model is implemented to simulate the seasonal changes of surface and subsurface currents and circulation in the North Indian Ocean and to examine the response to different wind forcing. The solution with three active layers reproduces the robust features of the North Indian Ocean when forced with the real wind observations from the ERS-1 Scatterometer winds. As the Indian Ocean circulation depends mainly on the seasonally reversing monsoon winds, it is very important to use real winds to get a clear picture of the circulation pattern. Although most ocean models of this region are forced with climatological or ECMWF winds, in this study wind fields measured by the ERS-1 Scatterometer provide the forcing for the same period of the T/P altimeter data. The free sea surface height (FSSH) is calculated from the model at 10-day snapshots, to match the time period of the T/P altimeter cycles. The model simulations show the spaceborne scatterometers to be the most useful tool to provide wind forcing for ocean models.
University of Southampton
Subrahmanyam, Bulusu
ca82a499-6a0e-4db2-b31d-2a4a0c2612f4
1998
Subrahmanyam, Bulusu
ca82a499-6a0e-4db2-b31d-2a4a0c2612f4
Subrahmanyam, Bulusu
(1998)
A study of the Indian Ocean circulation using satellite observations and model simulations.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Indian Ocean circulation is studied using remotely-sensed satellite observations of sea surface height, sea surface temperature and surface winds to gain a more complete view of the surface circulation than is possible from hydrographic studies alone. The instruments used are, respectively, TOPEX/POSEIDON (T/P) altimeter, ERS-1 Along-Track Scanning Radiometer (ATSR) and Scatterometer during 1993-1995.
The Somali eddies and possible formation mechanisms in the Arabian Sea are studied. The most energetic eddies found along the Somali coast depend on the monsoon system. The western boundary current, East India Coastal Current (EICC), in the Bay of Bengal is detected and analysed. Because of the scarcity of measured data in this region, satellite observations are required to examine the mechanisms which are involved in driving the EICC. Kelvin waves and Rossby waves in the Indian Ocean are identified and their role in energy transfer to the western boundary currents and to the eddies is examined. Kelvin and Rossby wave phase speeds are computed using two dimensional Fast Fourier Transforms (FFT) and Complex Principal Component (CPCA) Analysis. The phase speeds calculated from T/P altimetric observations are comparable to recent work by Killworth et al. (1997).
A simple isopycnic N-layer wind-driven model is implemented to simulate the seasonal changes of surface and subsurface currents and circulation in the North Indian Ocean and to examine the response to different wind forcing. The solution with three active layers reproduces the robust features of the North Indian Ocean when forced with the real wind observations from the ERS-1 Scatterometer winds. As the Indian Ocean circulation depends mainly on the seasonally reversing monsoon winds, it is very important to use real winds to get a clear picture of the circulation pattern. Although most ocean models of this region are forced with climatological or ECMWF winds, in this study wind fields measured by the ERS-1 Scatterometer provide the forcing for the same period of the T/P altimeter data. The free sea surface height (FSSH) is calculated from the model at 10-day snapshots, to match the time period of the T/P altimeter cycles. The model simulations show the spaceborne scatterometers to be the most useful tool to provide wind forcing for ocean models.
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Published date: 1998
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Local EPrints ID: 463333
URI: http://eprints.soton.ac.uk/id/eprint/463333
PURE UUID: be62a1b5-acad-4f88-8597-d9d13e50a140
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Date deposited: 04 Jul 2022 20:50
Last modified: 04 Jul 2022 20:50
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Author:
Bulusu Subrahmanyam
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