Torres, M., Pizarro, O., Dewitte, B., and Oerder, V. (2024)
Presented at:
Ocean Sciences Meeting 2024The deep ocean circulation is a key component of the Earth climate system, it contributes to the distribution and transport of heat, greenhouse gases and dissolved substances that are relevant to the life in the oceans. Despite its relevance, there are wide regions of the oceans where this circulation remains poorly understood, due in part to the scarcity of measurements and the difficulties involved in directly measuring deep ocean flows. In the eastern South Pacific off Chile, historical data consistently suggest the presence of a southward flow between about 1500 m and 3500 m that can be associated with the mid-depth outflow of the Pacific. Nevertheless, the dynamics and variability of this flow remains one of the least known of this kind in the world ocean. In this study, velocity, and hydrographic fields from ECCO and GLORYS12 reanalyzes are used to study the impact of Rossby waves on the deep ocean in the Chile basin. Our results show that El Niño-La Niña cycles generate large extratropical Rossby waves that propagate across the Chile basin impacting the deep ocean. Large interannual variability in meridional currents is related to this low frequency Rossby waves. Associated to these waves, near the coast, there is a vertical propagation of energy from the thermocline towards the deep ocean, which dissipates below 1500 m depth. This process contributes to mixing and affects the dynamics of the deep southward outflow.
