2012 Project Summary Sensitivity Patterns of Atlantic Meridional Overturning and Related Climate Diagnostics over the Instrumental Period

• Main Authors: Pis Patrick Heimbach, Rui P. Ponte, Carl Wunsch
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Lagrange; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.433.7254; http://www.usclivar.org/sites/default/files/amoc/Heimbach_2012AMOC_projsum.pdf

The long-‐term goals are to understand, with a comprehensive data set and a state-‐of-‐the-‐art ocean model, the nature of the North Atlantic Ocean circulation, with a particular emphasis on its decadal variability and climate consequences. The so-‐called meridional overturning circulation (MOC) is a simplified schematic of the complex North Atlantic Ocean circulation that is believed important to the climate system. As such, it is a useful shorthand for the description of circulation changes (past, ongoing, and possibly in the future) that can have serious climate implications and consequences for society in general. Adjoint models, which provide comprehensive sensitivities, are used to study the MOC in four distinct, but nonetheless, overlapping ways. In one approach, the adjoint is used as a numerical tool for fitting a general circulation model to a great variety of oceanic observations. Approach 2 exploits explicitly the mathematical result that the adjoint solution (the Lagrange multipliers) are the sensitivity of an arbitrarily chosen scalar-‐ function, for example, climate metrics that capture Atlantic transport and heat content variability, to almost any perturbation in the model or its external constraints (initial and boundary conditions). Approach 3 extends the adjoint application through formulating an