Antarctic Bottom Water sensitivity to spatio-temporal variations in
Antarctic meltwater fluxes
Abstract
Ice sheet melting into the Southern Ocean can change the formation and
properties of the Antarctic Bottom Water (AABW). Climate models
generally mimic ice sheet melting by adding uniformly-distributed
freshwater fluxes in the Southern Ocean. Uniform fluxes misrepresent the
heterogeneous Antarctic ice sheet melting patterns, and could bias AABW
representation in models. We use a global ocean and sea-ice model to
explore whether the spatial distribution and increases in freshwater
fluxes can alter AABW properties, formation, and the Antarctic sea-ice
area. We find that a realistic spatially varying flux sustains AABW with
higher salinities compared to simulations with uniform meltwater fluxes.
Finally, we show that a ~ 20% increase in ice sheet
melting can trigger AABW freshening and Antarctic sea-ice expansion
rates similar to those observed in the Southern Ocean since 1980,
suggesting that the increasing Antarctic meltwater discharge can drive
the observed AABW freshening and the Antarctic sea-ice expansion.