Challenges with interpreting the impact of Atlantic Multidecadal Variability using SST-restoring experiments

Abstract Climate model simulations that restore SSTs in the North Atlantic have been used to explore the climate impacts of Atlantic Multidecadal Variability (AMV). However, despite simulations and observations exhibiting similar North Atlantic SST anomalies, experiments with active SST-restoring in...

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Bibliographic Details
Published in:npj Climate and Atmospheric Science
Main Authors: Christopher H. O’Reilly, Matthew Patterson, Jon Robson, Paul Arthur Monerie, Daniel Hodson, Yohan Ruprich-Robert
Format: Article in Journal/Newspaper
Language:English
Published: Nature Portfolio 2023
Subjects:
Environmental sciences
GE1-350
Meteorology. Climatology
QC851-999
Pacific
North Atlantic
Online Access:https://doi.org/10.1038/s41612-023-00335-0
https://doaj.org/article/afa819f8ec274e50bafb253418fbf428
Description
Summary:Abstract Climate model simulations that restore SSTs in the North Atlantic have been used to explore the climate impacts of Atlantic Multidecadal Variability (AMV). However, despite simulations and observations exhibiting similar North Atlantic SST anomalies, experiments with active SST-restoring in the Tropical North Atlantic exhibit strong positive surface heat-fluxes out of the ocean with warm SST anomalies, which is not replicated in other simulations or observations. The upward surface heat-fluxes that are systematically driven by the active SST-restoring in the Tropical North Atlantic are found to be crucial for generating a strong local precipitation response and the associated remote impact on the Pacific Walker circulation; these are both absent in other simulations. The results of this study strongly suggest that experiments employing SST-restoring (or prescribed SSTs) in the Tropical North Atlantic exaggerate the influence of the Atlantic on patterns of global climate anomalies and its role in recent multidecadal SST trends.

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