Greatbatch, Richard John , Claus, Martin , Brandt, Peter , Matthießen, Jan-Dirk, Tuchen, Franz Philip , Ascani, François, Dengler, Marcus , Toole, John, Roth, Christina and Farrar, J. Thomas (2018) Evidence for the maintenance of slowly varying equatorial currents by intraseasonal variability. Geophysical Research Letters, 45 (4). pp. 1923-1929. DOI 10.1002/2017GL076662.

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Abstract

Recent evidence from mooring data in the equatorial Atlantic reveals that semi-annual and longer time scale ocean current variability is close to being resonant with equatorial basin modes. Here we show that intraseasonal variability, with time scales of 10's of days, provides the energy to maintain these resonant basin modes against dissipation. The mechanism is analogous to that by which storm systems in the atmosphere act to maintain the atmospheric jet stream. We demonstrate the mechanism using an idealised model set-up that exhibits equatorial deep jets. The results are supported by direct analysis of available mooring data from the equatorial Atlantic Ocean covering a depth range of several thousand meters. The analysis of the mooring data suggests that the same mechanism also helps maintain the seasonal variability.

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