Surface and Subsurface Geostrophic Current Variability in the Indian Ocean from Altimetry

Abstract

Geostrophic currents were calculated at the surface and subsurface levels in the Indian Ocean using satellite altimetry data from TOPEX/POSEIDON and Jason-1, a geoid obtained from the GRACE mission, and historical hydrographic profiles from the World Ocean Atlas 2005. The results of this method were validated with currents measured using Acoustic Doppler Current Profilers moored along the equator at 77°E, 83°E, and 93°E. The measured and computed currents compared reasonably well with similar features present in both. The presence of the seasonal Wyrtki Jets and Equatorial Undercurrent and their variability from 2000–2001 was observed in the estimated currents.

Keywords:

• ADCP currents
• altimetry
• equatorial jets
• Indian Ocean
• surface and subsurface geostrophic currents

Acknowledgements

This work was supported in part by the NASA Physical Oceanography Program under Grant NNG06GJ22G awarded to B.S; D.D.H.C. was supported in part by a South Carolina Space Grant Consortium Graduate Fellowship. V.S.N.M. acknowledges the funding support by the Ministry of Earth Sciences (MoES), Government of India, New Delhi for the current meter moorings program in the equatorial Indian Ocean. Finally, we wish to express our appreciation for the careful and thoughtful comments on the manuscript by two anonymous reviewers.