A Recent θ-S Shift in the Deep Water of the Northern North Atlantic

  1. James E. Hansen and
  2. Taro Takahashi
  1. James H. Swift

Published Online: 19 MAR 2013

DOI: 10.1029/GM029p0039

Climate Processes and Climate Sensitivity

Climate Processes and Climate Sensitivity

How to Cite

Swift, J. H. (1984) A Recent θ-S Shift in the Deep Water of the Northern North Atlantic, in Climate Processes and Climate Sensitivity (eds J. E. Hansen and T. Takahashi), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM029p0039

Author Information

  1. Marine Life Research Group, Scripps Institution of Oceanography, La Jolla, CA

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1984

ISBN Information

Print ISBN: 9780875904047

Online ISBN: 9781118666036

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Keywords:

  • Climatology—Congresses;
  • Geophysics—Congresses;
  • Ocean-atmosphere interaction—Congresses

Summary

North Atlantic ocean data from the Transient Tracers in the Ocean North Atlantic Study (1981) show that a deep water θ-S shift has occurred since GEOSECS (1972). For a given density, the deep water north of 50°N is now colder by about 0.15°C and less saline by about 0.02×10−3. Other hydrographic properties such as dissolved oxygen have also changed, but the configuration of the deep density fields is nearly unchanged. The deep changes were observed in at least three distinct deep water masses. Although the shifts are nearly universal north of 50°N, they have not yet spread significantly south of the Grand Banks. The reduced deep water salinities are caused by a freshening since the mid-1970's of the upper layers in the deep water mass formation regions. This upper-layer freshening may in turn be related to shifts in the large-scale atmospheric forcing over the northern North Atlantic and Norwegian-Greenland Sea.