Ning Cao a,b,c, Qiong Zhang b,c,?, Katherine Elizabeth Power b,c, Frederik Schenk c,d,e, Klaus Wyser c,f , Haijun Yang g,h a

College of Ocean and Meteorology and CMA-GDOU Joint Laboratory for Marine Meteorology, Guangdong Ocean University, Zhanjiang, 524088, China b Department of Physical Geography, Stockholm University, Stockholm, 10691, Sweden c Bolin Centre for Climate Research, Stockholm University, Stockholm, 10691, Sweden d Department of Geological Sciences, Stockholm University, Stockholm, 10691, Sweden e Department of Geosciences and Geography, University of Helsinki, Helsinki, 00014, Finland f Swedish Meteorological and Hydrological Institute (SMHI), Norrk?ping, 60176, Sweden g Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Science and CMA-FDU Joint Laboratory of Marine Meteorology, Fudan University, Shanghai, 200438, China h Shanghai Scientific Frontier Base for Ocean-Atmosphere Interaction Studies, Fudan University, Shanghai, 200438, China

a b s t r a c t

A significant multi-centennial climate variability with a distinct peak at approximately 200 years is observed in a pre-industrial (PI) control simulation using the EC-Earth3-LR climate model. This oscillation originates predominately from the North Atlantic and displays a strong association with the Atlantic Meridional Overturning Circulation (AMOC). Our study identifies the interplay between salinity advection feedback and vertical mixing in the subpolar North Atlantic as key roles in providing the continues internal energy source to maintain this multi-centennial oscillation. The perturbation flow of mean subtropical-subpolar salinity gradients serves as positive feedback to sustain the AMOC anomaly, while the mean advection of salinity anomalies and the vertical mixing or convection acts as negative feedback, constraining the AMOC anomaly. Notably, this low-frequency variability persists even in a warmer climate with weakened AMOC, emphasizing the robustness of the salinity advection feedback mechanism.