Open AccessSurface Flux Drivers for the Slowdown of the Atlantic Meridional Overturning Circulation in a High‐Resolution Global Coupled Climate Model
Author(s) -
Putrasahan D. A.,
Lohmann K.,
Storch J.S.,
Jungclaus J. H.,
Gutjahr O.,
Haak H.
Publication year - 2019
Publication title -
journal of advances in modeling earth systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.03
H-Index - 58
ISSN - 1942-2466
DOI - 10.1029/2018ms001447
Subject(s) - shutdown of thermohaline circulation , thermohaline circulation , ocean gyre , slowdown , climatology , ocean current , convection , flux (metallurgy) , circulation (fluid dynamics) , environmental science , walker circulation , climate model , north atlantic deep water , atmospheric sciences , geology , oceanography , subtropics , sea surface temperature , climate change , meteorology , physics , mechanics , materials science , fishery , political science , law , metallurgy , biology
This paper investigates the causation for the decline of the Atlantic Meridional Overturning Circulation (AMOC) from approximately 17 Sv to about 9 Sv, when the atmospheric resolution of the Max Planck Institute‐Earth System Model is enhanced from ∼1° to ∼0.5°. The results show that the slowdown of the AMOC is caused by the cessation of deep convection. In most modeling studies, this is thought to be controlled by buoyancy fluxes in the convective regions, for example, by surface freshwater flux that is introduced locally or via enormous input from glacier or iceberg melts. While we find that freshwater is still the key to the reduction of AMOC seen in the higher‐resolution run, the freshening of the North Atlantic does not need to be directly caused by local freshwater fluxes. Instead, it can be caused indirectly through winds via a reduced wind‐driven gyre circulation and salinity transport associated to this circulation, as seen in the higher‐resolution run.