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Poleward propagation of spiciness anomalies in the North Atlantic Ocean
Author(s) -
Laurian Audine,
Lazar Alban,
Reverdin Gilles,
Rodgers Keith,
Terray Pascal
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026155
Subject(s) - geology , salinity , oceanography , forcing (mathematics) , climatology , outcrop , thermohaline circulation , upwelling , mixed layer , gulf stream , subduction , water mass , geomorphology , seismology , tectonics
Recent modelling results suggest that subsurface salinity anomalies propagating from the tropics can reach and precondition the deep‐water formation regions, thus modulating the THC variability. The forcing and propagative aspects of this mechanism are presented in the North Atlantic Ocean over 1948–2002 using an OGCM. Density compensated salinity anomalies of 0.1 up to 0.35 psu along σ = 26 kg.m −3 are generated in the salinity maximum region at interannual to decadal frequency. The relation between subsurface conditions and late winter sea surface salinity variability supports the subduction mechanism. They circulate over isopycnals ranging from 25.6σ to 26.2σ at current speed between 150 m and 250 m depth toward Cape Hatteras via the Gulf of Mexico on a typical 6‐year transit. Although mixing along the pathway reduces the amplitude of salinity anomalies by about 66%, they largely determine the subsurface spiciness of the Gulf Stream up to 30°N, upstream of the outcrop region.