Atlantic equatorial deep jets in Argo float data

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