Deterministic role of salinity advection feedback in the
multi-centennial variability of AMOC revealed in an EC-Earth simulation
Abstract
Significant multi-centennial climate variability with a clear peak at
approximately 200 years is found in a pre-industrial control simulation
conducted with the EC-Earth3 climate model. The oscillation mainly
emerges from the North Atlantic and appears to be closely associated
with the Atlantic Meridional Overturning Circulation (AMOC). By
examining the salinity advection feedback, we find that the perturbation
flow of mean subtropical-subpolar salinity gradients in the subpolar
area governs as positive feedback to the AMOC anomaly. Meanwhile, the
mean advection of salinity anomalies and the vertical mixing or
convection acts as negative feedback to restrain the AMOC anomaly. In a
warmer climate, although the AMOC becomes weaker, such low-frequency
variability still exists, indicating the robustness of the salinity
advection feedback mechanism.