On the contribution of Rossby waves driven by surface buoyancy fluxes to low-frequency North Atlantic steric sea surface height variations

TL;DR

This study extends the classical Rossby wave model to include surface buoyancy fluxes and assesses their role in low-frequency North Atlantic steric sea surface height variations, revealing significant contributions especially in the eastern subpolar region.

Contribution

The paper introduces a modified Rossby wave model incorporating surface buoyancy forcing to evaluate its impact on sea surface height variations in the North Atlantic.

Findings

Wind-driven Rossby waves dominate in tropical-to-mid-latitudes.

Buoyancy-forced Rossby waves are significant in the eastern subpolar North Atlantic.

Together, they explain up to 50% of low-frequency steric SSH variations.

Abstract

Previous studies have shown that wind-forced baroclinic Rossby waves can capture a large portion of low-frequency steric SSH variations in the North Atlantic. In this paper, we extend the classical wind-driven Rossby wave model derived in a 1.5 layer ocean to include surface buoyancy forcing, and then use it to assess the contribution from buoyancy-forced Rossby waves to low-frequency North Atlantic steric SSH variations. In the tropical-to-mid-latitude North Atlantic we find that wind-driven Rossby waves are dominant, however, in the eastern subpolar North Atlantic their contribution is roughly the same as that of buoyancy-forced Rossby waves, where together they capture up to 50% of low-frequency steric SSH variations.