3 Results
3.1 Uniform versus spatially varying freshwater fluxes
Compared to the uniform freshwater flux experiment (UNIF ),
results from the spatially varying freshwater flux experiment
(VARI, Fig 2) show significant salinity anomalies. At the
surface, the Amundsen Sea coast becomes 0.5±0.12 PSU fresher inVARI while the remaining Antarctic coast increases in salinity by
up to 0.2±0.07 PSU (Fig 2a), thus reflecting the concentration of the
freshwater fluxes along the Amundsen Sea (Fig 1d). In the bottom layer,
salinity in the Southern Ocean (i.e., poleward of
60oS) increases up to 0.1±0.06 PSU (Fig 2d) inVARI. The average AABW salinity increases by
1.9±0.60×10-3 PSU in VARI compared toUNIF . Thus, the bottom cell of the Southern Ocean’s overturning
circulation extends to denser waters, but the transport of the bottom
cell stays approximately the same between the UNIF andVARI (Fig 2c).
A transect along the Antarctic shelf shows that positive surface
salinity anomalies in the VARI experiment are advected downwards
along the shelf to the bottom layer (Fig 2f). The downward advection of
high salinity anomalies happens mostly in the Ross Seas where the shelf
overflow is parameterized in CESM1 (Fig 2f). Therefore, overflow
parameterization has a key role in transmitting surface salinity signals
to the deep ocean. Once in the bottom layer, the positive salinity
anomalies spread laterally increasing in AABW salinity across the
Southern Ocean (Fig 2f).