Zonal intermediate currents in the equatorial Atlantic Ocean

Acoustic float data collected near 800 m depth, are used to map zonal mean currents within the Antarctic Intermediate Water (AAIW) tongue in the equatorial Atlantic. Alternating zonal jets of 2° latitudinal width are revealed between 6°S and 6°N. Displacements from profiling floats drifting near 1000 m depth, also reveal similar zonal jets at the base of the AAIW layer. The strongest jets (15 cm s−1 peak) are found at 4°S, 2°S, 0°, 2°N and 4°N. They are coherent longitudinally over order of 3000 km and, poleward of 1°S and 1°N, generally coherent vertically between 800 m and 1000 m. Large seasonal fluctuations exist at both levels: within 1° of equator, AAIW at 800 m flows westward (8 cm s−1 mean) in boreal summer and fall but eastward (3 cm s−1 mean) in winter, whereas the flow at 1000 m is eastward in late fall and winter.

Keyword(s)

Seasonal fluctuations, Float data, Zonal current, Antarctic intermediate Water, Equatorial Atlantic ocean

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Ollitrault Michel, Lankhorst Matthias, Fratantoni David, Richardson Philip, Zenk Walter (2006). Zonal intermediate currents in the equatorial Atlantic Ocean. Geophysical Research Letters. 33, https://doi.org/10.1029/2005GL025368, https://archimer.ifremer.fr/doc/00000/1112/

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