caa a22 4500 605471711 CHVBK 20210128100334.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00382-014-2391-2 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2391-2 Multimodel analysis on the response of the AMOC under an increase of radiative forcing and its symmetrical reversal [Elektronische Daten] [Giovanni Sgubin, Didier Swingedouw, Sybren Drijfhout, Stefan Hagemann, Eddy Robertson] The response of the Atlantic meridional overturning circulation (AMOC) to an increase of radiative forcing (ramp-up) and a subsequent reversal of radiative forcing (ramp-down) is analyzed for four different global climate models. Due to changes in ocean temperature and hydrological cycle, all models show a weakening of the AMOC during the ramp-up phase. Once the external forcing is reversed, the results become model dependent. For IPSL-CM5A-LR, the AMOC continues its weakening trend for most of the ramp-down experiment. For HadGEM2-ES, the AMOC trend reverses once the external forcing also reverses, without recovering its initial value. For EC-EARTH and MPI-ESM-LR the recovery is anomalously strong yielding an AMOC overshoot. A robust linear dependency can be established between AMOC and density difference between North Atlantic (NA) deep water formation region and South Atlantic (SA). In particular, AMOC evolution is primarily controlled by a meridional salinity contrast between these regions. During the warming scenario, the subtropical Atlantic becomes saltier while the NA experiences a net freshening which favours an AMOC weakening. The different behaviour in the models during the ramp-down is dependent on the response of the ocean at the boundaries of NA and SA. The way in which the positive salinity anomaly stored in the subtropical Atlantic during the ramp-up is subsequently released elsewhere, characterizes the recovery. An out-of-phase response of the salinity transport at $$48^{\circ }\hbox {N}$$ 48 ∘ N and $$34^{\circ }\hbox {S}$$ 34 ∘ S boundaries is able to control the meridional density contrast between NA and SA during the transient experiments. Such a non-synchronized response is mainly controlled by changes in gyre salinity transport rather than by changes in overturning transport, thus suggesting a small role of the salt advection feedback in the evolution of the AMOC. Springer-Verlag Berlin Heidelberg, 2014 Climate modelling nationallicence Global warming nationallicence Atlantic meridional overturning circulation nationallicence AMOC stability nationallicence Salt advection feedback nationallicence Reversibility nationallicence Sgubin Giovanni Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Bordeaux, France aut Swingedouw Didier Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Bordeaux, France aut Drijfhout Sybren Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands aut Hagemann Stefan Max Planck Institute for Meteorology (MPI-M), Hamburg, Germany aut Robertson Eddy Met Office Hadley Centre, Exeter, UK aut Climate Dynamics Springer Berlin Heidelberg 45/5-6(2015-09-01), 1429-1450 0930-7575 45:5-6<1429 2015 45 382 https://doi.org/10.1007/s00382-014-2391-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2391-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sgubin Giovanni Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Bordeaux, France aut NATIONALLICENCE 700 1- Swingedouw Didier Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Bordeaux, France aut NATIONALLICENCE 700 1- Drijfhout Sybren Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands aut NATIONALLICENCE 700 1- Hagemann Stefan Max Planck Institute for Meteorology (MPI-M), Hamburg, Germany aut NATIONALLICENCE 700 1- Robertson Eddy Met Office Hadley Centre, Exeter, UK aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/5-6(2015-09-01), 1429-1450 0930-7575 45:5-6<1429 2015 45 382