An efficient exact adjoint of the parallel MIT General Circulation Model, generated via automatic differentiation

(I) Ocean State Estimation [1, 2] I Given: – a set of (possibly different types of) observations – a numerical model & set of initial / boundary conditions I Question: (estimation / optimal control problem) Find optimal trajectory consistent with observations within prior error I Approach: Minimize least square function J (~u) measuring model vs. data misfit −→ seek ~ ∇uJ (~u) to infer update ∆~u from variation of controls ~u