The 2023 marine heatwave in the North Atlantic tropical ocean

Loubet, Amélie; van Gennip, Simon J.; Bourdallé-Badie, Romain; Drevillon, Marie

doi:https://doi.org/10.5194/sp-6-osr9-11-2025

Articles | Volume 6-osr9

https://doi.org/10.5194/sp-6-osr9-11-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Report:

9th edition of the Copernicus Ocean State Report (OSR9)

https://doi.org/10.5194/sp-6-osr9-11-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 6-osr9

30 Sep 2025

| OSR9 | Chapter 4.1

| 30 Sep 2025 | OSR9 | Chapter 4.1

The 2023 marine heatwave in the North Atlantic tropical ocean

Amélie Loubet, Simon J. van Gennip, Romain Bourdallé-Badie, and Marie Drevillon

Data sets

Global Ocean Physics Reanalysis EU Copernicus Marine Service Product (CMEMS) https://doi.org/10.48670/moi-00021

ERA5 hourly data on single levels from 1940 to present Hans Hersbach et al. https://doi.org/10.24381/cds.adbb2d47

Short summary

Marine heatwaves (MHWs) are intensifying due to climate change. In 2023, the Copernicus Marine forecast system tracked a significant MHW event in the North Atlantic tropical ocean. We show this event was unprecedented, at the surface and at depth. It peaked in the north-east in May, spreading south-west to reach the Caribbean by autumn. In the east and centre parts, the MHW remained within the surface layers, while in the Caribbean, it reached deeper levels due to warm waters advected by equatorial eddies.