Atlantic equatorial deep jets in Argo float data

Abstract

<p>Equatorial deep jets (EDJ) are strong zonal currents in the deep tropical oceans that alternate in direction with depth and<br>time. In the Atlantic below the thermocline, they are the dominant variability on interannual timescales. They propagate<br>energy upwards and are suggested to impact surface climate variables on interannual timescales. They are also<br>important for the distribution of tracer in the mid-depth tropical ocean, for example by enhanced oxygen ventilation of<br>the eastern deep oxygen minimum zones, both through advection by the EDJ themselves and because the EDJ<br>nonlinearly drive time mean flow. Observations of equatorial deep jets are available but scarce, given the EDJs’ location<br>at depth and their long periodicity of several years. In the last few years, Argo floats have added a significant amount of<br>measurements at intermediate depth. We therefore perfomed a new EDJ scale analysis based on Argo float<br>measurements, the results of which we show here. At 1000 m depth, very weak or no EDJ signals can be detected in the<br>Indian and Pacific Oceans. In the Atlantic, however, the EDJ signal is strong at 1000 m depth, allowing us to obtain<br>good estimates of their frequency, amplitude, phase, zonal wavelength, and meridional structure.</p>