EGU24-15728, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

AMOC representation in the North Atlantic in a forced ocean model

Simon Wett1,2,3, Monika Rhein2,3, Arne Biastoch4,5, and Eleanor Frajka-Williams1
Simon Wett et al.
  • 1Institute of Oceanography, Universität Hamburg, Hamburg, Germany
  • 2Institute of Environmental Physics, Universität Bremen, Bremen, Germany
  • 3MARUM Centre for Marine Environmental Sciences, Bremen, Germany
  • 4GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 5Christian-Albrechts Universität zu Kiel, Kiel, Germany

The Atlantic Meridional Overturning Circulation (AMOC) plays a vital role in the climate of Europe and the North Atlantic region by redistributing heat and freshwater in the Atlantic. Climate model studies project an AMOC decline under global warming in the 21st century. However, they disagree on the magnitude and timescales of the weakening. Thus, assessing model performance regarding the representation of the AMOC remains essential. Observational estimates can serve as important benchmarks to understand AMOC variability in ocean models. AMOC observations at different monitoring arrays in the North Atlantic have shown strong variability on multiple time scales and no long-term trend. We analyze the AMOC at the North Atlantic Changes (NOAC) array line at 47°N in the high-resolution forced VIKING20X model simulation from 1980 to 2021. The mean AMOC strength is within the range of the NOAC observations. However, the VIKING20X AMOC exhibits a decreasing trend from the mid-1990s until 2010. This decrease coincides with significant cooling and freshening in the subpolar North Atlantic in VIKING20X. In agreement with NOAC observations, VIKING20X shows meridional connectivity between the NOAC and RAPID AMOC when the NOAC AMOC leads by about one year, though less distinct. This agreement indicates a common mechanism, determining the meridional connectivity in observations and VIKING20X. These mechanisms must be understood and represented in climate models to make informed projections of the future AMOC and its role in the climate system. Furthermore, ocean models and gridded observational data sets could help complement new approaches to monitoring the AMOC at key locations using novel methods and instrumentation, such as drift-free bottom pressure sensors, which could help resolve the geostrophic reference level.

How to cite: Wett, S., Rhein, M., Biastoch, A., and Frajka-Williams, E.: AMOC representation in the North Atlantic in a forced ocean model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15728,, 2024.