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Sea surface height variability in the Indian Ocean from TOPEX/POSEIDON altimetry and model simulations

Sea surface height variability in the Indian Ocean from TOPEX/POSEIDON altimetry and model simulations
Sea surface height variability in the Indian Ocean from TOPEX/POSEIDON altimetry and model simulations
Sea Surface Height (SSH) variability in the Indian Ocean during 1993-1995 is studied using TOPEX/POSEIDON (T/P) altimetry data. Strong interannual variability is seen in the surface circulation of the western Arabian Sea, especially in the Somali eddy structure. During the Southwest (SW) monsoon, a weak monsoon year is characterized by a single eddy system off Somalia, a strong or normal monsoon year by several energetic eddies. The Laccadive High (LH) and Laccadive Low (LL) systems off southwest India are observed in the altimetric SSH record. The variability of the East India Coastal Current (EICC), the western boundary current in the Bay of Bengal, is also detected. Evidence is found for the propagation of Kelvin and Rossby waves across the northern Indian Ocean; these are examined in the context of energy transfer to the western boundary currents, and associated eddies. A simple wind-driven isopycnal model having three active layers is implemented to simulate the seasonal changes of surface and subsurface circulation in the North Indian Ocean and to examine the response to different wind forcing. The wind forcing is derived from the ERS-1 scatterometer wind stress for the same period as the T/P altimeter data, enabling the model response in different (active/weak) monsoon conditions to be tested. The model output is derived in 10-day snapshots to match the time period of the T/P altimeter cycles. Complex Principal Component Analysis (CPCA) is applied to both altimetric and model SSH data. This confirms that long Rossby waves are excited by the remotely forced Kelvin waves off the southwest coast of India and contribute substantially to the variability of the seasonal circulation in the Arabian Sea.
TOPEX-POSEIDON, SATELLITE ALTIMETRY, SEA LEVEL MEASUREMENTS, PLANETARY WAVES, KELVIN WAVES, INDIAN OCEAN
0149-0419
167-195
Subrahmanyam, B.
e4e91c95-4319-4755-b05b-34759d3a8ef7
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc
Subrahmanyam, B.
e4e91c95-4319-4755-b05b-34759d3a8ef7
Robinson, I.S.
548399f7-f9eb-41ea-a28d-a248d3011edc

Subrahmanyam, B. and Robinson, I.S. (2000) Sea surface height variability in the Indian Ocean from TOPEX/POSEIDON altimetry and model simulations. Marine Geodesy, 23 (3), 167-195. (doi:10.1080/01490410050128609).

Record type: Article

Abstract

Sea Surface Height (SSH) variability in the Indian Ocean during 1993-1995 is studied using TOPEX/POSEIDON (T/P) altimetry data. Strong interannual variability is seen in the surface circulation of the western Arabian Sea, especially in the Somali eddy structure. During the Southwest (SW) monsoon, a weak monsoon year is characterized by a single eddy system off Somalia, a strong or normal monsoon year by several energetic eddies. The Laccadive High (LH) and Laccadive Low (LL) systems off southwest India are observed in the altimetric SSH record. The variability of the East India Coastal Current (EICC), the western boundary current in the Bay of Bengal, is also detected. Evidence is found for the propagation of Kelvin and Rossby waves across the northern Indian Ocean; these are examined in the context of energy transfer to the western boundary currents, and associated eddies. A simple wind-driven isopycnal model having three active layers is implemented to simulate the seasonal changes of surface and subsurface circulation in the North Indian Ocean and to examine the response to different wind forcing. The wind forcing is derived from the ERS-1 scatterometer wind stress for the same period as the T/P altimeter data, enabling the model response in different (active/weak) monsoon conditions to be tested. The model output is derived in 10-day snapshots to match the time period of the T/P altimeter cycles. Complex Principal Component Analysis (CPCA) is applied to both altimetric and model SSH data. This confirms that long Rossby waves are excited by the remotely forced Kelvin waves off the southwest coast of India and contribute substantially to the variability of the seasonal circulation in the Arabian Sea.

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More information

Published date: 2000
Keywords: TOPEX-POSEIDON, SATELLITE ALTIMETRY, SEA LEVEL MEASUREMENTS, PLANETARY WAVES, KELVIN WAVES, INDIAN OCEAN

Identifiers

Local EPrints ID: 8886
URI: https://eprints.soton.ac.uk/id/eprint/8886
ISSN: 0149-0419
PURE UUID: 5072249e-0f6b-484f-93a0-b850d4fe93a1

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Date deposited: 13 Sep 2004
Last modified: 17 Jul 2017 17:12

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