SAMW is a very homogeneous layer that forms north of the Sub-Antarctic Front and is also referred to as a pycnostad.
Its uniformity can be attributed to convective overturning that also serves to ventilate it, resulting in the high dissolved oxygen value of >6mL/L.
From west to east, the density increases from 1026.9 kg/m3 to 1027.1 kg/m3, the temperature decreases from 8.5 °C to 5.5 °C, and the salinity decreases from 34.62 ppt to 34.25 ppt (psu) [2] In the region where the Peru-Chile Undercurrent flows above the SAMW, the SAMW can be distinguished as having locally-characteristic low phosphorus, silicate and other nutrient concentrations in comparison.
In the event of global heating due to climate change, the amount of carbon dioxide that the SAMW is able to absorb will lessen.
Downes et al. (2009)[5] found that through climate modeling, in the event of a doubling of atmospheric carbon dioxide concentration the Subantarctic Mode water will decrease in density and salinity.