@article{ad24c3eeda3a49a79ddb0b29244a5b9e,
title = "Evaluation of subtropical North Atlantic ocean circulation in CMIP5 models against the observational array at 26.5°N and its changes under continued warming",
abstract = "Observationally based metrics derived from the Rapid Climate Change (RAPID) array are used to assess the large-scale ocean circulation in the subtropical North Atlantic simulated in a suite of fully coupled climate models that contributed to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The modeled circulation at 26.58N is decomposed into four components similar to those RAPID observes to estimate the Atlantic meridional overturning circulation (AMOC): the northward-flowing western boundary current (WBC), the southward transport in the upper midocean, the near-surface Ekman transport, and the southward deep ocean transport. The decadal-meanAMOCand the transports associated with its flow are captured well by CMIP5 models at the start of the twenty-first century. By the end of the century, under representative concentration pathway 8.5 (RCP8.5), averaged across models, the northward transport of waters in the upper WBCis projected to weaken by 7.6 Sv (1 Sv[106m3 s-1 ; - 21%). This reduced northward flow is a combined result of a reduction in the subtropical gyre return flow in the upper ocean (-2.9 Sv; 212%) and a weakened net southward transport in the deep ocean (-4.4 Sv; 228%) corresponding to the weakened AMOC. No consistent long-term changes of the Ekman transport are found across models. The reduced southward transport in the upper ocean is associated with a reduction in wind stress curl (WSC) across the North Atlantic subtropical gyre, largely through Sverdrup balance. This reduced WSC and the resulting decrease in the horizontal gyre transport is a robust feature found across the CMIP5 models under increased CO2 forcing.",
keywords = "Atmosphere-ocean interaction, Climate models, Model comparison, Ocean, Ocean circulation, Ocean dynamics",
author = "Beadling, {R. L.} and Russell, {J. L.} and Stouffer, {R. J.} and Goodman, {P. J.}",
note = "Funding Information: Acknowledgments. We acknowledge the World Climate Research Programme{\textquoteright}s Working Group on Coupled Modelling responsible for CMIP. We thank the modeling groups listed in Table 1 for producing and making available their output. For CMIP, the U.S. Department of Energy{\textquoteright}s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. Data from the RAPID-WATCH MOC monitoring project are funded by the Natural Environment Research Council and are freely available (www.rapid.ac.uk/rapidmoc). We acknowledge the use of the Ferret program from NOAA{\textquoteright}s Pacific Marine Environmental Laboratory for analysis and graphics (http:// ferret.pmel.noaa.gov/Ferret). Figure 1 was created using the Ocean Data View software (Schlitzer 2016), with the CFC-11 data obtained by repeat hydrographic measurements and made freely available from the Global Ocean Data Analysis Project, version 2 (GLODAPv2; Key et al. 2015; Lauvset et al. 2016; Olsen et al. 2016). We extend a huge thank you to Dr. Lynne Talley and Dr. Isabella Rosso from Scripps Institution of Oceanography, Dr. Alison Gray from the University of Washington, and to the editor and reviewers for their valuable insights, comments, and suggestions. This research was funded by the U.S. EPA Assistance Agreement FP-91780701-0. This publication has not been reviewed by the EPA and the views expressed herein are solely those of the authors. This work was sponsored by NSF{\textquoteright}s Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project under the NSF Award PLR-1425989, with additional support from NOAA and NASA. Logistical support for SOCCOM in the Antarctic was provided by the U.S. NSF through the U.S. Antarctic Program. Funding Information: We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling responsible for CMIP. We thank the modeling groups listed in Table 1 for producing and making available their output. For CMIP, the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. Data from the RAPID-WATCH MOC monitoring project are funded by the Natural Environment Research Council and are freely available (www.rapid.ac.uk/rapidmoc).We acknowledge the use of the Ferret program from NOAA's Pacific Marine Environmental Laboratory for analysis and graphics (http:// ferret.pmel.noaa.gov/Ferret). Figure 1 was created using the Ocean Data View software (Schlitzer 2016), with the CFC-11 data obtained by repeat hydrographic measurements and made freely available from the Global Ocean Data Analysis Project, version 2 (GLODAPv2; Key et al. 2015; Lauvset et al. 2016; Olsen et al. 2016). We extend a huge thank you to Dr. Lynne Talley and Dr. Isabella Rosso from Scripps Institution ofOceanography,Dr.Alison Gray from the University of Washington, and to the editor and reviewers for their valuable insights, comments, and suggestions. This research was funded by the U.S. EPA Assistance Agreement FP-91780701-0. This publication has not been reviewed by the EPA and the views expressed herein are solely those of the authors. This work was sponsored by NSF's Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project under the NSF Award PLR-1425989, with additional support from NOAA and NASA. Logistical support for SOCCOMin the Antarctic was provided by the U.S. NSF through the U.S. Antarctic Program. Publisher Copyright: {\textcopyright} 2018 American Meteorological Society.",
year = "2018",
month = dec,
day = "1",
doi = "10.1175/JCLI-D-17-0845.1",
language = "English (US)",
volume = "31",
pages = "9697--9718",
journal = "Journal of Climate",
issn = "0894-8755",
publisher = "American Meteorological Society",
number = "23",
}