(American Geophysical Union, 2006-08-17)
Moses, Christopher S.; Swart, Peter K.; Rosenheim, Brad E.
Ocean circulation and global climate are strongly influenced by
seawater density, which is itself controlled by salinity and temperature.
Although adequate instrumental sea-surface temperature (SST) records
exist for most of the surface oceans over the past 100-150 years, records of
salinity really only exist for the last 40-50 years. Here we show that
longer proxy records from corals (Siderastrea radians) in the eastern
tropical North Atlantic are dominated by multi-decadal variations in
salinity which are correlated with the relationship between SST and the
North Atlantic Oscillation (NAO) over the course of the 20th century. The
data reveal an increase in eastern tropical North Atlantic salinity of +0.5
psu between about 1950-1990. Rather than a monotonic secular increase,
as indicated by some instrumental records, the pre-instrumental coral
proxy records presented here suggest that salinity in the tropical North
Atlantic is periodic on a decadal to multi-decadal scale.
