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Warming of the Global Ocean: Spatial Structure and Water-Mass TrendsThis study investigates the multidecadal warming and interannual-to-decadal heat content changes in the upper ocean (0-700 m), focusing on vertical and horizontal patterns of variability. These results support a nearly monotonic warming over much of the World Ocean, with a shift toward Southern Hemisphere warming during the well-observed past decade. This is based on objectively analyzed gridded observational datasets and on a modeled state estimate. Besides the surface warming, a warming climate also has a subsurface effect manifesting as a strong deepening of the midthermocline isopycnals, which can be diagnosed directly from hydrographic data. This deepening appears to be a result of heat entering via subduction and spreading laterally from the high-latitude ventilation regions of subtropical mode waters. The basin-average multidecadal warming mainly expands the subtropical mode water volume, with weak changes in the temperature-salinity (u-S) relationship (known as ''spice'' variability). However, the spice contribution to the heat content can be locally large, for example in Southern Hemisphere. Multidecadal isopycnal sinking has been strongest over the southern basins and weaker elsewhere with the exception of the Gulf Stream/North Atlantic Current/subtropical recirculation gyre. At interannual to decadal time scales, wind-driven sinking and shoaling of density surfaces still dominate ocean heat content changes, while the contribution from temperature changes along density surfaces tends to decrease as time scales shorten.
Document ID
Document Type
Reprint (Version printed in journal)
Hakkinen, Sirpa (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rhines, Peter B. (Washington Univ. Seattle, WA, United States)
Worthen, Denise L. (Wyle Science, Technology and Engineering Group Houston, TX, United States)
Date Acquired
July 6, 2016
Publication Date
July 1, 2016
Publication Information
Publication: American Meterological Society
Volume: 29
Issue: 13
Subject Category
Report/Patent Number
Funding Number(s)
Distribution Limits
Global Ocean