Optimal Transition Paths for AMOC Collapse and Recovery in a Stochastic Box Model ...

• Main Authors: Soons, Jelle, Grafke, Tobias, Dijkstra, Henk A.
• Format: Report
• Language: unknown
• Published: arXiv 2023
• Subjects: Atmospheric and Oceanic Physics physics.ao-ph; Probability math.PR; FOS Physical sciences; FOS Mathematics; North Atlantic
• Online Access: https://dx.doi.org/10.48550/arxiv.2311.12734; https://arxiv.org/abs/2311.12734

The present-day Atlantic Meridional Overturning Circulation (AMOC) is considered to be in a bi-stable regime and hence it is important to determine probabilities and pathways for noise-induced transitions between its equilibrium states. Here, using Large Deviation Theory (LDT), the most probable transition pathways for the collapse and recovery of the AMOC are computed in a stochastic box model of the World Ocean. This allows us to determine the physical mechanisms of noise-induced AMOC transitions. We show that the most likely path of an AMOC collapse starts paradoxically with a strengthening of the AMOC followed by an immediate drop within a couple of years due to a short but relatively strong freshwater pulse. The recovery on the other hand is a slow process, where the North Atlantic needs to be gradually salinified over a course of 20 years. The proposed method provides several benefits, including an estimate of probability ratios of collapse between various freshwater noise scenarios, showing that the ...