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Ocean Science An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 6 | Copyright
Ocean Sci., 11, 953-963, 2015
https://doi.org/10.5194/os-11-953-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 11 Dec 2015

Research article | 11 Dec 2015

Monitoring Atlantic overturning circulation and transport variability with GRACE-type ocean bottom pressure observations – a sensitivity study

K. Bentel, F. W. Landerer, and C. Boening K. Bentel et al.
  • Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109, USA

Abstract. The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism for large-scale northward heat transport and thus plays an important role for global climate. Relatively warm water is transported northward in the upper layers of the North Atlantic Ocean and, after cooling at subpolar latitudes, sinks down and is transported back south in the deeper limb of the AMOC. The utility of in situ ocean bottom pressure (OBP) observations to infer AMOC changes at single latitudes has been characterized in the recent literature using output from ocean models. We extend the analysis and examine the utility of space-based observations of time-variable gravity and the inversion for ocean bottom pressure to monitor AMOC changes and variability between 20 and 60° N. Consistent with previous results, we find a strong correlation between the AMOC signal and OBP variations, mainly along the western slope of the Atlantic Basin. We then use synthetic OBP data – smoothed and filtered to resemble the resolution of the GRACE (Gravity Recovery and Climate Experiment) gravity mission, but without errors – and reconstruct geostrophic AMOC transport. Due to the coarse resolution of GRACE-like OBP fields, we find that leakage of signal across the step slopes of the ocean basin is a significant challenge at certain latitudes. Transport signal rms is of a similar order of magnitude as error rms for the reconstructed time series. However, the interannual AMOC anomaly time series can be recovered from 20 years of monthly GRACE-like OBP fields with errors less than 1 sverdrup in many locations.

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The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism for large-scale northward heat transport and plays an important role for global climate. Previously, AMOC changes have been inferred from in situ ocean bottom pressure (OBP) observations at single latitudes. We extend the analysis to space-based observations (and the whole North Atlantic) and show on data from the ECCO2 model that AMOC anomalies can be inferred from OBP at a resolution resembling the GRACE gravity mission.
The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism for large-scale...
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