Premium
A twenty year reversal in water mass trends in the subtropical North Atlantic
Author(s) -
Leadbetter S. J.,
Williams R. G.,
McDonagh E. L.,
King B. A.
Publication year - 2007
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 - 10.1029/2007gl029957
Subject(s) - thermocline , water mass , oceanography , geology , outflow , salinity , north atlantic deep water , subtropics , water column , ekman transport , temperature salinity diagrams , climatology , environmental science , atmospheric sciences , thermohaline circulation , upwelling , fishery , biology
Temperature and salinity changes have been compared along three repeat sections at 36°N in the North Atlantic. The principal changes, cooling of the upper waters and warming of the intermediate waters observed between 1959 and 1981, were reversed between 1981 and 2005. The controlling mechanisms for the changes over the two time periods differed through the water column. Neutral density surfaces over the upper 800 m were firstly uplifted and secondly depressed by typically 50 m, which is broadly consistent with the changes in thermocline thickness implied by the temporal changes in Ekman pumping. In contrast, the intermediate waters (800–2500 m) firstly became warmer and saltier and secondly became cooler and fresher. This change in the intermediate waters was controlled by water mass changes along neutral density surfaces suggesting a change in the source waters, principally Labrador Sea Water and Mediterranean Outflow Water.