Characterisation of Atlantic meridional overturning hysteresis using Langevin dynamics

Hysteresis diagrams of the Atlantic meridional overturning circulation (AMOC) under freshwater forcing from climate models of intermediate complexity are fitted to a simple model based on the Langevin equation. A total of six parameters are sufficient to quantitatively describe the collapses seen in these simulations. Reversing the freshwater forcing results in asymmetric behaviour that is less well captured and appears to require a more complicated model. The Langevin model allows for comparison between models that display an AMOC collapse. Differences between the climate models studied here are mainly due to the strength of the stable AMOC and the strength of the response to a freshwater forcing.

Automated summary

This study fits hysteresis diagrams of the Atlantic meridional overturning circulation (AMOC) from climate models of intermediate complexity to a simple model based on the Langevin equation. The results show that a total of six parameters are needed to quantitatively describe the collapses seen in these simulations. Reversing the freshwater forcing leads to asymmetric behavior that requires a more complex model to capture, indicating differences mainly due to the strength of the stable AMOC and the response to freshwater forcing in the climate models studied.