Talley, L. D., Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA, ltalley@ucsd.edu
Sprintall, J. ., Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA, jsprintall@ucsd.edu
McDonagh, E. ., National Oceanography Centre, Southampton, United Kingdom, elm@noc.soton.ac.uk
Swift, J. S., Scripps Institution of Oceanography, UCSD, La Jolla, CA, USA, jswift@ucsd.edu
Mecking, S. ., University of Washington, Seattle, WA, USA, smecking@apl.washington.edu
Bindoff, N. ., University of Tasmania, Hobart, Tasmania, Australia, n.bindoff@utas.edu.au
GLOBAL-SCALE, DECADAL CHANGES IN SALINITY AND OXYGEN BASED ON RECENT REPEAT HYDROGRAPHIC SECTIONS
Salinity and oxygen variations are examined from each ocean basin, using repeat hydrographic data, including chlorofluorocarbons that provide time-scale information. Results are considered with respect to basin-wide analyses of salinity and oxygen trends (Boyer et al., 2005; Garcia et al., 2005). The upper ocean freshened in regions of fresher water (high latitudes and Pacific Ocean), and became saltier in more saline regions (subtropical latitudes and Atlantic Ocean), suggesting a strengthening of the normal atmospheric water transport. Reported oxygen decreases in the northern hemisphere mid-latitude thermoclines suggest a widespread slowing of thermocline ventilation (Emerson et al., 2004; Deutsch et al., 2005; Johnson and Gruber, 2006). However, the upper thermoclines of all three southern basin subtropical gyres show increased oxygen, suggesting a increase in southern hemisphere circulation that could be related to recent observations of increased dynamic height and strengthened southern hemisphere westerlies. These changes are shallower than the Antarctic Intermediate Water and within and above the Subantarctic Mode Water, which originate close to the Antarctic Circumpolar Current. Both the salinity and subtropical oxygen changes are consistent with anthropogenic change.