Authors:

Polina Verezemskaya¹², Sergey Gulev¹², Bernard Barnier², Jean-Marc Molines², Pedro Colombo³, Alexander Gavrikov¹

Affiliations:

  • 1. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
  • 2. Institut des Geosciences de l'Environment, University Grenoble-Alpes, Grenoble, France
  • 3. Climate Change Research Center, University of New South Wales, Sydney, Australia

Plain-Text Summary:

The dynamics of the North Atlantic subpolar gyre (SPG) play a crucial role in controlling the Atlantic Meridional Overturning Circulation (AMOC), which significantly impacts global climate variability. This study introduces an innovative regional eddy-resolving model of the subpolar North Atlantic, built on the NEMO4 configuration. The model aims to address the misrepresentation of key ocean processes that are pivotal in the SPG, such as Gulf Stream detachment, eddy activity, deep convection, and overflows.

We assessed the model's performance using a range of observational datasets, including in situ measurements and remote sensing data. Through rigorous comparisons, we found that the model effectively captured essential ocean dynamics, leading to a better understanding of the SPG's behavior. Notably, the study highlights the sensitivity of the model's performance to various numerical schemes and parameterizations, particularly focusing on the momentum advection scheme, current feedback parameterization, and the implementation of a local-sigma vertical coordinate system.

The findings indicate that the new model configuration can replicate the intricate behaviors of ocean eddies and deep convection processes more accurately than previous models. By providing a more realistic representation of the North Atlantic’s ocean dynamics, this research opens pathways for future studies on climate variability and oceanic processes. Our work emphasizes the importance of refining ocean models to enhance predictive capabilities regarding climate fluctuations and the global ocean's health.

Experiments` results:

Experiment Features Physics Dynamics Comment
MP415 NAAD HiRes atmospheric forcing Basic* UBS+explicit viscosity Reference experiment
MP415b Test (1993–1995) Basic UBS Too noisy, fewer living eddies
MP415d Test (1993–1995) Basic EEN Too noisy, fewer coherent eddies
MP416 Current feedback parameterization CFB UBS + explicit viscosity More kinetic energy loss
MP418 CSWL inclusion into ECMWF flux scheme Cool-skin parameterization UBS + explicit viscosity Changes in surface flux estimate
MP420 Both CFB and Cool-skin effects Cool-skin, CFB UBS + explicit viscosity Consistent result
MP421 All improvements at once Cool-skin parameterization, CFB UBS + explicit viscosity, local sigma Inclusive experiment