Indirect small-scale turbulence and mixing estimates in the Southwest Atlantic

• Grant number: 25/09004-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Physical Oceanography
• Principal Investigator: César Barbedo Rocha
• Grantee: Mariana de Souza Barros
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 23/10506-0 - Small scales matter: the role of submesoscale dynamics in large-scale ocean circulation and climate, AP.JP

Abstract

Theoretical models and observational heat and volume budgets suggest that turbulent mixing is the primary driver of the abyssal cell of the Atlantic Meridional Overturning Circulation (AMOC). However, the magnitude and temporal variability of turbulent mixing in the abyssal ocean remain poorly understood. This project aims to estimate the annual and interannual variability of turbulent kinetic energy dissipation and turbulent diffusivity in the Southwest Atlantic by applying finescale parameterizations to density and velocity profiles. We will use observations collected over the past decade along the 34.5°S line by the SAMOC/SAMBA program, as well as density profiles obtained from autonomous Deep Argo floats. This represents the first systematic effort to quantify these parameters in the region where Antarctic Bottom Water (AABW) transport is most intense. The results will contribute to the evaluation of theoretical and numerical models of AMOC variability and its implications for the global climate system. (AU)