Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products
- 1k Downloads
The mean and variability of the Atlantic meridional overturning circulation (AMOC), as represented in six ocean reanalysis products, are analyzed over the period 1960–2007. Particular focus is on multi-decadal trends and interannual variability at 26.5°N and 45°N. For four of the six reanalysis products, corresponding reference simulations obtained from the same models and forcing datasets but without the imposition of subsurface data constraints are included for comparison. An emphasis is placed on identifying general characteristics of the reanalysis representation of AMOC relative to their reference simulations without subsurface data constraints. The AMOC as simulated in these two sets are presented in the context of results from the Coordinated Ocean-ice Reference Experiments phase II (CORE-II) effort, wherein a common interannually varying atmospheric forcing data set was used to force a large and diverse set of global ocean-ice models. Relative to the reference simulations and CORE-II forced model simulations it is shown that (1) the reanalysis products tend to have greater AMOC mean strength and enhanced variance and (2) the reanalysis products are less consistent in their year-to-year AMOC changes. We also find that relative to the reference simulations (but not the CORE-II forced model simulations) the reanalysis products tend to have enhanced multi-decadal trends (from 1975–1995 to 1995–2007) in the mid to high latitudes of the northern hemisphere.
KeywordsAtlantic meridional overturning circulation (AMOC) Ocean data assimilation Ocean synthesis Ocean reanalysis Ocean reconstruction Decadal prediction
We wish to thank Keith Haines and Maria Valdivieso for early discussions and contributions. D.S. acknowledges the hospitality during a stimulating and pleasant research visit to the Climate and Global Dynamics division at NCAR. This work contributes to the Excellence Initiative “CliSAP” of the Universität Hamburg, funded through the German Science Foundation (DFG). D.M.S. was supported by the joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101) and the EU FP7 SPECS project. A.R.K. was funded through the NOAA Climate Program Office under the Climate Variability and Predictability Program grants NA09OAR4310163 and NA13OAR4310138, and by the NSF Collaborative Research EaSM2 Grant OCE-1243015. NCAR is sponsored by the National Science Foundation.
All relevant funding sources have been disclosed in the Acknowledgments. All authors of this paper provided consent to submit this work to Climate Dynamics.
Compliance with ethical standards
Conflict of interest
There are no potential conflicts of interest that would jeopardize the objectivity of this research.
This research did not involve any human participants or animals.
- Antonov J, Locarnini R, Boyer T, Mishonov A, Garcia H (2006) World Ocean Atlas 2005, volume 2: salinity. In: Levitus S (ed) NOAA Atlas NESDIS 62. U.S. Government Printing Office, WashingtonGoogle Scholar
- Bingham R, Hughes C, Roussenov V, Williams R (2007) Meridional coherence of the North Atlantic meridional overturning circulation. Geophys Res Lett 34(L23):606Google Scholar
- Boyer T et al (2010) World ocean database 2009. In: Levitus S (ed) NOAA Atlas NESDIS 66. U.S. Government Printing Office, WashingtonGoogle Scholar
- Chang YS, Zhang S, Rosati A, Delworth T, Stern W (2012) An assessment of oceanic variability for 1960–2010 from the GFDL ensemble coupled data assimilation. Clim Dyn 40(3):775–803Google Scholar
- Danabasoglu G et al (2015) North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Inter-Annual to Decadal Variability, Part II. Ocean Model (in press)Google Scholar
- Fujii Y, Tsujino H, Toyoda T, Nakano H (2015) Enhancement of the southward return flow of the Atlantic Meridional Overturning Circulation by data assimilation and its influence in an assimilative ocean simulation forced by CORE-II atmospheric forcing. Clim Dyn. doi: 10.1007/s00382-015-2780-1 Google Scholar
- Griffies S (2005) Some ocean model fundamentals. In: Chassignet EP, and J. Verron J (eds) Ocean weather forecasting: an integrated view of oceanography. Springer, BerlinGoogle Scholar
- Griffies S, Winton M, Samuels B, Danabasoglu G, Yeager S, Marsland S, Drange H, Bentsen M (2012) Datasets and protocol for the CLIVAR WGOMD Coordinated Ocean sea-ice Reference Experiments (COREs). Technical Report 21/2012, World Climate Research Program (WCRP)Google Scholar
- Hamilton D (1994) GTSPP builds an ocean temperature-salinity database. Earth Syst Monit 4(4):4–5Google Scholar
- Hunke E, Lipscomb W (2008) CICE: the Los Alamos Sea Ice Model Documentation and Software User’s Manual. Version 4.0. Technical Report LA-CC-06-012, T-3 Fluid Dynamics Group, Los Alamos National LaboratoryGoogle Scholar
- Locarnini R, Mishonov A, Antonov J, Boyer T, Garcia H, Baranova O, Zweng M, Johnson D (2010) World Ocean Atlas 2009, volume 1: temperature. In: Levitus S (ed) NOAA Atlas NESDIS 68. U.S. Government Printing Office, WashingtonGoogle Scholar
- Madec G (2001) NEMO reference manual, ocean dynamics component. NEMO-OPA. Preliminary version. Note du Pole de modelisation 27, Institut Pierre-Simon Laplace (IPSL), FranceGoogle Scholar
- McCarthy G, Frajka-Williams E, Johns WE, Baringer MO, Meinen CS, Bryden HL, Rayner D, Duchez A, Roberts C, Cunningham SA (2012) Observed interannual variability of the Atlantic meridional overturning circulation at 26.5°N. Geophys Res Lett 39:L19609. doi: 10.1029/2012GL052933
- Mogensen K, Molteni MBR, Weaver A (2012) The NEMOVAR ocean data assimilation system as implemented in the ECMWF ocean analysis system for System 4. ECMWF Tech. Mem. 668, European Centre for Medium-Range Weather Forecasts, Reading, England. Available online at http://www.ecmwf.int/publications/
- Robson J, Sutton R, Smith D (2012) Initialized decadal predictions of the rapid warming of the North Atlantic Ocean in the mid 1990’s. Geophys Res Lett 39(L19):713Google Scholar
- Smith R et al (2010b) The Parallel Ocean Program (POP) Reference Manual, Ocean Component of the Community Climate System Model (CCSM) and Community Earth System Model (CESM). LANL Tech. Rep LAUR-10-01853, Los Alamos National Laboratory, Los Alamos, NMGoogle Scholar
- Tsujino H, Motoi T, Ishikawa I, Hirabara M, Nakano H, Yamanaka G, Yasuda T, Ishizaki H (2001) Reference manual for the Meteorological Research Institute Community Ocean Model (MRI.COM) Version 3. Technical Report 59, Meteorological Research InstituteGoogle Scholar
- Tsujino H, Hirabara M, Nakano H, Yasuda T, Motoi T, Yamanaka G (2011) Simulating present climate of the global ocean–ice system using the Meteorological Research Institute Community Ocean Model (MRI.COM): simulation characteristics and variability in the Pacific sector. J Oceanogr 67:449–479CrossRefGoogle Scholar
- Zhang R, Delworth T (2006) Impact of Atlantic multidecadal oscillations on India/Sahel rainfall and Atlantic hurricanes. Geophys Res Lett 33(L17):712Google Scholar