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Title: A new look at ocean ventilation time scales and their uncertainties

Abstract

Abstract A suite of eddy‐resolving ocean transient tracer model simulations are first compared to observations. Observational and model pCFC‐11 ages agree quite well, with the eddy‐resolving model adding detail. The CFC ages show that the thermocline is a barrier to interior ocean exchange with the atmosphere on time scales of 45 years, the measureable CFC transient, although there are exceptions. Next, model simulations are used to quantify effects on tracer ages of the spatial dependence of internal ocean tracer variability due to stirring from eddies and biases from nonstationarity of the atmospheric transient when there is mixing. These add to tracer age uncertainties and biases, which are large in frontal boundary regions, and small in subtropical gyre interiors. These uncertainties and biases are used to reinterpret observed temporal trends in tracer‐derived ventilation time scales taken from observations more than a decade apart, and to assess whether interpretations of changes in tracer ages being due to changes in ocean ventilation hold water. For the southern hemisphere subtropical gyres, we infer that the rate of ocean ventilation 26–27.2 σ θ increased between the mid‐1990s and the decade of the 2000s. However, between the mid‐1990s and the decade of the 2010s, there ismore » no significant trend—perhaps except for South Atlantic. Observed age/AOU/ventilation changes are linked to a combination of natural cycles and climate change, and there is regional variability. Thus, for the future it is not clear how strong or steady in space and time ocean ventilation changes will be.« less

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [2]
  1. Department of Ocean Sciences University of Miami Miami Florida USA
  2. National Center for Atmospheric Research Boulder Colorado USA
  3. Los Alamos National Laboratory Los Alamos New Mexico USA
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)
Contributing Org.:
National Center for Atmospheric Research, Boulder, CO (United States)
OSTI Identifier:
1355937
Alternate Identifier(s):
OSTI ID: 1355938; OSTI ID: 1356159
Report Number(s):
LA-UR-17-23369
Journal ID: ISSN 2169-9275
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Geophysical Research. Oceans
Additional Journal Information:
Journal Name: Journal of Geophysical Research. Oceans Journal Volume: 122 Journal Issue: 5; Journal ID: ISSN 2169-9275
Publisher:
American Geophysical Union (AGU)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Earth Sciences

Citation Formats

Fine, Rana A., Peacock, Synte, Maltrud, Mathew E., and Bryan, Frank O. A new look at ocean ventilation time scales and their uncertainties. United States: N. p., 2017. Web. doi:10.1002/2016JC012529.
Fine, Rana A., Peacock, Synte, Maltrud, Mathew E., & Bryan, Frank O. A new look at ocean ventilation time scales and their uncertainties. United States. https://doi.org/10.1002/2016JC012529
Fine, Rana A., Peacock, Synte, Maltrud, Mathew E., and Bryan, Frank O. 2017. "A new look at ocean ventilation time scales and their uncertainties". United States. https://doi.org/10.1002/2016JC012529.
@article{osti_1355937,
title = {A new look at ocean ventilation time scales and their uncertainties},
author = {Fine, Rana A. and Peacock, Synte and Maltrud, Mathew E. and Bryan, Frank O.},
abstractNote = {Abstract A suite of eddy‐resolving ocean transient tracer model simulations are first compared to observations. Observational and model pCFC‐11 ages agree quite well, with the eddy‐resolving model adding detail. The CFC ages show that the thermocline is a barrier to interior ocean exchange with the atmosphere on time scales of 45 years, the measureable CFC transient, although there are exceptions. Next, model simulations are used to quantify effects on tracer ages of the spatial dependence of internal ocean tracer variability due to stirring from eddies and biases from nonstationarity of the atmospheric transient when there is mixing. These add to tracer age uncertainties and biases, which are large in frontal boundary regions, and small in subtropical gyre interiors. These uncertainties and biases are used to reinterpret observed temporal trends in tracer‐derived ventilation time scales taken from observations more than a decade apart, and to assess whether interpretations of changes in tracer ages being due to changes in ocean ventilation hold water. For the southern hemisphere subtropical gyres, we infer that the rate of ocean ventilation 26–27.2 σ θ increased between the mid‐1990s and the decade of the 2000s. However, between the mid‐1990s and the decade of the 2010s, there is no significant trend—perhaps except for South Atlantic. Observed age/AOU/ventilation changes are linked to a combination of natural cycles and climate change, and there is regional variability. Thus, for the future it is not clear how strong or steady in space and time ocean ventilation changes will be.},
doi = {10.1002/2016JC012529},
url = {https://www.osti.gov/biblio/1355937}, journal = {Journal of Geophysical Research. Oceans},
issn = {2169-9275},
number = 5,
volume = 122,
place = {United States},
year = {Mon May 08 00:00:00 EDT 2017},
month = {Mon May 08 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1002/2016JC012529

Citation Metrics:
Cited by: 28 works
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