Equatorial Deep Jets and Abyssal Mixing in the Indian Ocean

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Abstract
Vertical profiles of horizontal currents and hydrographic measurements from three cruises along 80.5°E from the coast of Sri Lanka to 6°S between December 1990 and September 1994 are used to investigate the scales of the Indian Ocean deep jets as well as internal wave parameters and dissipation at the equator. The deep jets at 80.5°E have a vertical wavelength of 660 sm (stretched meters) and amplitudes exceeding 10 cm s−1 in zonal velocity. They are observed throughout the water column and their flow direction reverses at 2° off the equator. The vertical positions of the jets differ among the cruises and are consistent with a flow reversal between the data collected in winter and summer. During September 1994, the jets were less pronounced. Due to the meridional distribution of their zonal velocity and the phase relationship between zonal velocity and vertical displacement, the jets are best described as nondispersive first-mode equatorial Rossby waves. The hydrographic data revealed thick layer... Abstract Vertical profiles of horizontal currents and hydrographic measurements from three cruises along 80.5°E from the coast of Sri Lanka to 6°S between December 1990 and September 1994 are used to investigate the scales of the Indian Ocean deep jets as well as internal wave parameters and dissipation at the equator. The deep jets at 80.5°E have a vertical wavelength of 660 sm (stretched meters) and amplitudes exceeding 10 cm s−1 in zonal velocity. They are observed throughout the water column and their flow direction reverses at 2° off the equator. The vertical positions of the jets differ among the cruises and are consistent with a flow reversal between the data collected in winter and summer. During September 1994, the jets were less pronounced. Due to the meridional distribution of their zonal velocity and the phase relationship between zonal velocity and vertical displacement, the jets are best described as nondispersive first-mode equatorial Rossby waves. The hydrographic data revealed thick layer...