Salinity, oxygen and nutrient variations are reviewed or examined from each ocean basin, using repeat hydrographic data, as background for this AGU session on variability in biogeochemistry with particular focus on the thermocline. Results are considered with respect to basin-wide analyses of salinity and oxygen trends (Boyer et al., 2005; Garcia et al., 2005). Upper ocean salinity changes suggest freshening in regions of fresher water (high latitudes and Pacific Ocean), and increased salinity in regions of saltier water (subtropical latitudes and Atlantic Ocean), suggesting a strengthening of the normal atmospheric water transport. These change are communicated to the ocean interior through water mass formation and subduction. Oxygen decreases in the extratropical thermoclines of the Atlantic, Pacific and Indian Oceans suggest a widespread slowing of thermocline ventilation (Emerson et al., 2004; Deutsch et al., 2005; Johnson and Gruber, 2006), although decadal variability may obscure any trend. Nutrient variations might not yet show consistent global variations, but regional analyses suggest that changing thermocline ventilation is a major factor.

UR: http://ushydro.ucsd.edu
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4532 General circulation (1218, 1222)
DE: 4536 Hydrography and tracers
SC: Ocean Sciences [OS]
MN: 2006 Fall Meeting