Simultaneous model spin-up and parameter identification with the one-shot method in a climate model example

Abstract

We investigate the One-shot Optimization strategy introduced in this form by Hamdi andGriewank for the applicability and efficiency to identify parameters in models of the earth's climatesystem. Parameters of a box model of the North Atlantic Thermohaline Circulation are optimizedwith respect to the Şt of model output to data given by another model of intermediate complexity.Since the model is run into a steady state by a pseudo time-stepping, efficient techniques are necessaryto avoid extensive recomputations or storing when using gradient-based local optimization algorithms.The One-shot approach simultaneously updates state, adjoint and parameter values. For the requiredpartial derivatives, the algorithmic/automatic differentiation tool TAF was used. Numerical resultsare compared to results obtained by the BFGS and L-BFGS quasi-Newton method.