Meridional overturning and oceanic heat transport circulation observations in the North Atlantic Ocean [in “State of the Climate in 2017”]

The Atlantic meridional overturning circulation (AMOC) and the Atlantic meridional heat transport (AMHT) carry warm near-surface water northward, provide heat to the atmosphere at northern latitudes, and carry colder deep water southward. Buckley and Marshall (2016) present a summary of the dynamical forcing mechanisms of the AMOC and AMHT and the role they play in regulating climate variability around the Atlantic sector. Owing to the large amounts of heat, carbon, and fresh water transported by the AMOC, climate models suggest accurate estimation of its rate of change is critical to understanding and predicting our changing climate (e.g., W. Liu et al. 2017; Rahmstorf et al. 2015). Even on short time scales the AMOC/AMHT can impact climate (e.g., Duchez et al. 2016). These recognitions have led to the implementation of enhanced observing systems of the strength of the AMOC in the subpolar North Atlantic (Lozier et al. 2017) and the subtropical South Atlantic (Ansorge et al. 2014). These new observing systems will eventually provide a more complete spatial picture of the state of the AMOC.