Equatorial Currents in the Western Indian Ocean

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Science  01 Aug 1980:
Vol. 209, Issue 4456, pp. 600-603
DOI: 10.1126/science.209.4456.600


Measurements were made in the equatorial Indian Ocean during spring and summer 1979 from the Somali coast to 62°E in the interior of the western basin. The detailed vertical profiles of horizontal current show that the energetic dominance throughout the region of variability was on vertical scales of several hundreds of meters, confined to within a few degrees of the equator, as observed in 1976. The near-surface equatorial circulation responded directly to variations in the wind field, and satellite-tracked drifter buoys showed the equatorial surface jet extending across the width of the ocean. This eastward flow is generated by the eastward winds that appear in the interval between the northeast and southwest monsoons. The zonal velocity fluctuations extended in a consistent pattern over the observation region. The time and meridional scales of the variability were similar to those observed in 1976, suggesting that the velocity field is dominated by long-term, equatorially trapped motions with long zonal scales.