Atlantic Equatorial Deep Jets in Argo Float Data

Abstract

Equatorial deep jets (EDJ) are zonal currents along the equator in all three ocean basins that alternate in direction with depth and time. In the Atlantic Ocean below the thermocline, they are the dominant variability on interannual time scales. Observations of equatorial deep jets are available but scarce, given the EDJs’ location at depth, their small vertical scale, and their long periodicity of several years. In the last few years, Argo floats have added a significant number of measurements at intermediate depth. In this study we therefore revise estimates of the EDJ scales based on Argo float data. Mostly, we use velocity data at 1000-m depth calculated from float displacement, which yield robust estimates of the Atlantic EDJ period (4.6 yr), amplitude distribution, phase distribution, zonal wavelength (146.7°), and meridional structure. We also show that the equatorial amplitude of the EDJs’ first meridional mode Rossby wave component (9.8 cm s