Princeton University, Program in Atmosphere and Ocean Sciences, Princeton, USA
Received: 26 Aug 2010 – Published in The Cryosphere Discuss.: 22 Oct 2010
Abstract. Hybrid models, or depth-integrated flow models that include the effect of both longitudinal stresses and vertical shearing, are becoming more prevalent in dynamical ice modeling. Under a wide range of conditions they closely approximate the well-known First Order stress balance, yet are of computationally lower dimension, and thus require less intensive resources. Concomitant with the development and use of these models is the need to perform inversions of observed data. Here, an inverse control method is extended to use a hybrid flow model as a forward model. We derive an adjoint of a hybrid model and use it for inversion of ice-stream basal traction from observed surface velocities. A novel aspect of the adjoint derivation is a retention of non-linearities in Glen's flow law. Experiments show that in some cases, including those nonlinearities is advantageous in minimization of the cost function, yielding a more efficient inversion procedure.
Revised: 18 Mar 2011 – Accepted: 24 Mar 2011 – Published: 13 Apr 2011
Goldberg, D. N. and Sergienko, O. V.: Data assimilation using a hybrid ice flow model, The Cryosphere, 5, 315-327, doi:10.5194/tc-5-315-2011, 2011.