Middepth decadal warming and freshening in the South Atlantic

South Atlantic Ocean middepth water property (temperature, salinity, oxygen, nutrients, etc.) distributions are set by salty, well-ventilated, and relatively nutrient-poor North Atlantic Deep Water (NADW) spreading southward toward the Southern Ocean underneath fresher, well-ventilated, and relatively nutrient-poor northward spreading Antarctic Intermediate Water (AAIW). The layer between the NADW and AAIW is oxygen-poor and nutrient-rich, with small vertical temperature gradients. Salinity stratification dominates the vertical density gradient, hence the layer is referred to as Salinity Stratified Layer (SSL). Decadal warming (0.044 degrees C decade(-1)) and freshening (0.006 g kg(-1) decade(-1)) of this layer are analyzed using Argo data, a climatology, and repeat hydrographic sections. Warming within the SSL accumulates heat at a rate of similar to 20 TW, is unlikely to be caused by vertical heave, and is consistent with anomalous southward advection of order 10(2) km decade(-1) in the Atlantic Meridional Overturning Circulation. Salinity changes within the SSL are consistent with a downward velocity anomaly of order 10 m decade(-1).