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

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 tra...

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Bibliographic Details
Main Authors: Soons, Jelle, Grafke, Tobias, Dijkstra, Henk A.
Format: Report
Language:unknown
Published: arXiv 2023
Subjects:
Online Access:https://dx.doi.org/10.48550/arxiv.2311.12734
https://arxiv.org/abs/2311.12734
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Summary: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 ...