Estimation of the Agulhas ring impacts on meridional heat fluxes and transport using ARGO floats and satellite data

Abstract

[1] A method that combines vertical profiles from the ARGO floats program and satellite Sea Surface Height (SSH) data is used to reconstruct the vertical structure of the Agulhas rings. All eddies shed by the Agulhas retroflection in the period between January 2005 and December 2008 were successfully reconstructed. The velocity structures obtained are tilted and phase shifted in relation to the temperature anomalies, resulting in an annual mean eddy meridional heat flux across the ring paths of 0.062 ± 0.012 PW (northward). A first order estimate indicates 0.07 PW entering the Atlantic from the Indian Ocean through Agulhas rings. The volume transport by Agulhas rings is believed to play a central role in the overturning circulation, being the main process responsible for the leakage of Indian Ocean waters to the Atlantic. The new estimates of the [time mean] ring volume transport of 9 ± 8 Sv from the Indian to the Atlantic Ocean fall in the range obtained by previous works. These estimates include a better representation of the trapped water region in the eddies. A large inter-annual variability in the volume transport was observed, with a maximum of ∼11–21 Sv in 2007. This variability is related to the number of structures shed by the Agulhas retroflexion per year. The ring shapes play a secondary, though important, role.