Dynamical stability indicator based on autoregressive moving-average models : critical transitions and the Atlantic meridional overturning circulation

• Published in: Chaos: An Interdisciplinary Journal of Nonlinear Science
• Main Authors: Rodal, Marie, Krumscheid, Sebastian, Madan, Gaurav, LaCasce, Joseph Henry, Vercauteren, Nikki
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: Mathematics; Physics; Greenland; Ice Sheet; North Atlantic
• Online Access: https://hdl.handle.net/10067/1927690151162165141; https://repository.uantwerpen.be/docstore/d:irua:15681

Abstract: A statistical indicator for dynamic stability, known as the Upsilon indicator, is used to gauge the stability and, hence, detect approaching tipping points of simulation data from a reduced five-box model of the North Atlantic Meridional Overturning Circulation (AMOC) exposed to a time-dependent hosing function. The hosing function simulates the influx of fresh water due to the melting of the Greenland ice sheet and increased precipitation in the North Atlantic. The Upsilon indicator is designed to detect changes in the memory properties of the dynamics and is based on fitting auto-regressive moving-average models in a sliding window approach to time series data. An increase in memory properties is interpreted as a sign of dynamical instability. The performance of the indicator is tested on time series subject to different types of tipping, namely, bifurcation-induced, noise-induced, and rate-induced tipping. The numerical analysis shows that the indicator indeed responds to the different types of induced instabilities. Finally, the indicator is applied to two AMOC time series from a full complexity Earth systems model (CESM2). Compared with the doubling CO2 scenario, the quadrupling CO2 scenario results in stronger dynamical instability of the AMOC during its weakening phase. Published under an exclusive license by AIP Publishing.