Sea surface height and steric height increases in the Southern Hemisphere

Abstract

Sea surface height has increased by 3 millimeters per year, globally averaged, since 1993. Some fraction of sea surface height change is due to added water from melting glaciers, for instance, and some is due to increasing heat and salinity changes (steric effects). Focusing on the Southern Hemisphere, Sutton and Roemmich analyzed temperature and salinity data from the Argo float array in relation to earlier data from the World Ocean Circulation Experiment (WOCE) to estimate the steric changes. These were compared with the total sea surface height changes over the same period seen in satellite altimetric data. They found that on decadal time scales, about half of the rise in sea surface height in the Southern Ocean is due to steric effects, with the proportion increasing southward. The accompanying increase in ocean heat content south of 30°S can account for most of the global heat content change during this period. (Geophysical Research Letters, doi:10.1029/2011GL046802, 2011)