Abstract
In coarse resolution ocean models, eddy diffusive effects are
parameterized with an isopycnal mixing coefficient, which controls
mixing strength along isopycnals. Both wind and isopycnal mixing affect
surface temperature and salinity in the Southern Ocean, influencing the
buoyancy of waters near Antarctica. Using an idealized MITgcm
basin-channel model, we varied both Southern Ocean wind stress and the
isopycnal mixing coefficient. We found that strong Southern Ocean winds
make the abyssal cell’s strength insensitive to isopycnal mixing, while
weak winds only allow AABW formation if the mixing coefficient exceeds
500 $m^2/s$. Higher isopycnal mixing brings warmer, saltier water
to the surface of the Southern Ocean, where it cools, becomes denser,
and forms AABW. Increasing the isopycnal mixing coefficient increases
the latitudinal span of negative surface buoyancy flux close to
Antarctica. Hence, changing the isopycnal mixing is likely to have an
impact on the water properties of AABW.