The importance of deep, basinwide measurements in optimized Atlantic Meridional Overturning Circulation observing arrays

• Main Authors: McCarthy, Gerard, Menary, M. B., Mecking, J. V., Moat, B. I., Johns, W. E., Andrews, B., Rayner, D., Smeed, D. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley Online Library 2017
• Subjects: North Atlantic
• Online Access: https://mural.maynoothuniversity.ie/12019/; https://mural.maynoothuniversity.ie/12019/1/GMc_The%20importance.pdf

The Atlantic Meridional Overturning Circulation (AMOC) is a key process in the global redistribution of heat. The AMOC is defined as the maximum of the overturning stream function, which typically occurs near 308N in the North Atlantic. The RAPID mooring array has provided full-depth, basinwide, continuous estimates of this quantity since 2004. Motivated by both the need to deliver near real-time data and optimization of the array to reduce costs, we consider alternative configurations of the mooring array. Results suggest that the variability observed since 2004 could be reproduced by a single tall mooring on the western boundary and a mooring to 1500 m on the eastern boundary. We consider the potential future evolution of the AMOC in two generations of the Hadley Centre climate models and a suite of additional CMIP5 models. The modeling studies show that deep, basinwide measurements are essential to capture correctly the future decline of the AMOC. We conclude that, while a reduced array could be useful for estimates of the AMOC on subseasonal to decadal time scales as part of a near real-time data delivery system, extreme caution must be applied to avoid the potential misinterpretation or absence of a climate time scale AMOC decline that is a key motivation for the maintenance of these observations.