Atlantic Meridional Overturning Circulation Near 41N from Altimetry and Argo Observations

Updated Jan 13, 2026 to include estimates through calendar year 2025.

These files contain an estimate of the Atlantic Meridional Overturning Circulation (AMOC) volume and heat transports, computed using observations of temperature, salinity and subsurface velocity from the Argo array of profiling floats (DOI: 10.17882/42182#116315), and satellite-based observations of sea level from altimetry (DOI: 10.48670/moi-00148 and DOI: 10.48670/moi-00149).  The estimates are computed using the techniques of Willis (2010) and Hobbs and Willis (2012). In addition, estimates of wind stress at the surface were estimated from European Center for Medium Range Weather Forecast, ERA5 analysis (DOI: 10.24381/cds.143582cf).

Note that in all files, although there are 12 time-steps per year, each time step represents a 3-month average, so the time series is over sampled.

The .txt file contains comma separated values of the time series, with 1 header line and the following columns, estimated as in Willis (2010) and Hobbs and Willis (2012): 

Column 1: Decimal year

Column 2: Ekman Volume Transport (Sverdrups)

Column 3: Northward Geostrophic Transport (Sverdrups)

Column 4: Meridional Overturning Volume Transport (Sverdrups)

Column 5: Meridional Overturning Heat Transport (PetaWatts)

The file called “trans_Argo_ERA5.nc” contains an estimate of the geostrophic transport as a function of latitude, longitude, depth and time, for the upper 2000 m for latitudes near 41 N in the Atlantic Ocean, estimated as described in Willis (2010). Also included are Ekman Transport and Overturning Transport as functions of time and latitude for this region.

The file called “Q_ARGO_obs_dens_2000depth_ERA5.nc” contains estimates of heat transport for these regions based on various assumptions about the temperature of the ocean at depths unmeasured by the Core Argo array (depths below 2000m), estimated as described in Hobbs and Willis (2012).  These assumptions are described in the variable “Hpar”.

If you use these data please cite:

Willis, J. K., and Hobbs, W. R., Atlantic Meridional Overturning Circulation Near 41N from Altimetry and Argo Observations. Dataset access [YYYY-MM-DD] at 10.5281/zenodo.8170366.

References & Acknowledgements:

Hobbs, W. R., and J. K. Willis (2012), Midlatitude North Atlantic heat transport: A time series based on satellite and drifter data. J. Geophys. Res., 117, C01008, doi:10.1029/2011JC007039.

Willis, J. K. (2010), Can in situ floats and satellite altimeters detect long-term changes in Atlantic Ocean overturning?, Geophys.  Res. Lett., 37, L06602, doi:10.1029/2010GL042372. http://www.agu.org/pubs/crossref/2010/2010GL042372.shtml

This study has been conducted using E.U. Copernicus Marine Service Information; https://doi.org/10.48670/moi-00149  and https://doi.org/10.48670/moi-00148

These data were collected and made freely available by the International Argo Program and the national programs that contribute to it.  (https://argo.ucsd.edu,  https://www.ocean-ops.org).  The Argo Program is part of the Global Ocean Observing System. “

Argo (2000). Argo float data and metadata from Global Data Assembly Centre (Argo GDAC). SEANOE. https://doi.org/10.17882/42182#116315

Hersbach, H., et al. (2017): Complete ERA5 from 1940: Fifth generation of ECMWF atmospheric reanalyses of the global climate. Copernicus Climate Change Service (C3S) Data Store (CDS). DOI: 10.24381/cds.143582cf  (Accessed on 24-Dec-2022)