Abstract

How do mesoscale eddies affect the Weddell Gyre strength? We investigate this by running an idealized model of the Weddell Gyre at eddy-parametrized, eddy-permitting, and eddy-rich resolutions and find that the gyre is strongly sensitive to horizontal resolution. The gyre transport is largest at eddy-permitting resolutions and smallest at eddy-parametrized resolutions. The eddy-permitting simulations have the largest horizontal density gradients and the weakest stratification over the gyre basin. The large horizontal density gradients induce a significant thermal wind transport and increase the mean available potential energy for mesoscale eddies. The distribution of eddy kinetic energy indicates that explicit eddies in simulations intensify the bottom circulation of the gyre via non-linear dynamics. We also find that the gyre transport is insensitive to large variations in the ACC strength. Estimates of the Weddell Gyre transport already vary widely between climate simulations. If climate models adopt horizontal resolutions that the Weddell Gyre is most sensitive to, then simulations of the Weddell Gyre could become more disparate.