Chaotic variability of the meridional overturning circulation on subannual to interannual timescales

Abstract

Observations and numerical simulations have shown that the meridional overturning circulation (MOC) exhibits substantial variability on sub-to interannual timescales. This variability is not fully understood. In particular it is not known what fraction of the MOC variability is caused by processes such as mesoscale ocean eddies and waves which are ubiquitous in the ocean. Here we analyse twin experiments performed with a global ocean model at eddying (1/4°) and non-eddying (1 ) resolutions. The twin experiments are forced with the same surface fluxes for the 1958 to 2001 period but start from different initial conditions. Our results show that on subannual to interannual timescales a large fraction of MOC variability directly reflects variability in the surface forcing. Nevertheless,. © 2013 Author(s).