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The deep ocean buoyancy budget and its temporal variability


Palter, JB and Griffies, SM and Samuels, BL and Galbraith, ED and Gnanadesikan, A and Klocker, A, The deep ocean buoyancy budget and its temporal variability, Journal of Climate, 27, (2) pp. 551-573. ISSN 0894-8755 (2014) [Refereed Article]


Copyright Statement

Copyright 2014 American Meteorological Society

DOI: doi:10.1175/JCLI-D-13-00016.1


Despite slow rates of ocean mixing, observational and modeling studies suggest that buoyancy is redistributed to all depths of the ocean on surprisingly short interannual to decadal time scales. The mechanisms responsible for this redistribution remain poorly understood. This work uses an Earth system model to evaluate the global steady-state ocean buoyancy (and related steric sea level) budget, its interannual variability, and its transient response to a doubling of CO2 over 70 years, with a focus on the deep ocean. At steady state, the simple view of vertical advective–diffusive balance for the deep ocean holds at low tomidlatitudes. At higher latitudes, the balance depends on a myriad of additional terms, namely mesoscale and submesoscale advection, convection and overflows from marginal seas, and terms related to the nonlinear equation of state. These high-latitude processes rapidly communicate anomalies in surface buoyancy forcing to the deep ocean locally; the deep, high-latitude changes then influence the large-scale advection of buoyancy to create transient deep buoyancy anomalies at lower latitudes. Following a doubling of atmospheric carbon dioxide concentrations, the high-latitude buoyancy sinks are suppressed by a slowdown in convection and reduced dense water formation. This change is accompanied by a slowing of both upper and lower cells of the global meridional overturning circulation, reducing the supply of dense water to low latitudes beneath the pycnocline and the commensurate flow of light waters to high latitudes above the pycnocline. By this mechanism, changes in high-latitude buoyancy are communicated to the global deep ocean on relatively fast advective time scales.

Item Details

Item Type:Refereed Article
Keywords:deep ocean buoyancy
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Understanding climate change not elsewhere classified
UTAS Author:Klocker, A (Dr Andreas Klocker)
ID Code:91546
Year Published:2014
Web of Science® Times Cited:20
Deposited By:IMAS Research and Education Centre
Deposited On:2014-05-21
Last Modified:2017-11-01
Downloads:359 View Download Statistics

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