Quantifying the contribution of ocean advection and surface flux to the
upper-ocean salinity variability resolved by climate model simulations
Abstract
This study examines the impact of ocean advection and surface freshwater
flux on the non-seasonal, upper-ocean salinity variability in two
climate model simulations with eddy-resolving and eddy-parameterized
ocean components (HR and LR, respectively). We assess the realism of
each simulation by comparing their sea surface salinity (SSS) variance
with satellite and Argo float estimates. Our results show that, in the
extratropics, the HR variance is about five times larger than that in LR
and agrees with the Argo estimates. In turn, the extratropical satellite
SSS variance is smaller than that from HR and Argo by about a factor of
two, potentially reflecting the low sensitivity of radiometers to SSS in
cold waters. Using a simplified salinity conservation equation for the
upper-50-m ocean layer, we find that the advection-driven variance in HR
is, on average, one order of magnitude larger than the surface
flux-driven variance, reflecting the action of mesoscale processes.