Monitoring the integrated deep meridional flow in the tropical North Atlantic: long-term performance of a geostrophic array

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: Kanzow, T., Send, U., Zenk, W., Chave, A.D., Rhein, M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2006
• Subjects: North Atlantic Deep Water; North Atlantic
• Online Access: http://nora.nerc.ac.uk/id/eprint/144194/; https://doi.org/10.1016/j.dsr.2005.12.007

As a component of the meridional overturning variability experiment in the tropical North Atlantic, a four-year-long time series of meridional transport of North Atlantic deep water has been obtained from moored end point measurements of density and bottom pressure. This study presents a quality assessment of the measurement elements. Rigorous pre- and post- deployment in situ calibration of the density sensors and subsequent data processing establish an accuracy of O(1.5 Sv) in internal transport in the 1200–5000 dbar range at subinertial time scales. A similar accuracy is reached in the bottom pressure-derived external transport fluctuations. However, for pressure, variability with periods longer than a deployment's duration (presently about one year) is not measurable. This effect is demonstrated using numerical simulations and a possible solution for detecting long-term external transport changes is presented.