1Nansen Environmental and Remote Sensing Center, Norway
2Bjerknes Center for Climate Research, Norway
3Institut des sciences de la mer, Université du Québec à Rimouski, Canada
Received: 28 Feb 2012 – Discussion started: 19 Mar 2012
Abstract. We consider the estimation of the grazing preferences parameters of zooplankton in ocean ecosystem models with ensemble-based Kalman filters. These parameters are introduced to model the relative diet composition of zooplankton that consists of phytoplankton, small size-classes of zooplankton and detritus. They are positive values and their sum is equal to one. However, the sum-to-one constraint cannot be guaranteed by ensemble-based Kalman filters when parameters are bounded. Therefore, a reformulation of the parameterization is proposed. We investigate two types of variable transformations for the estimation of positive sum-to-one constrained parameters that lead to the estimation of a new set of parameters with normal or bounded distributions. These transformations are illustrated and discussed with twin experiments performed with the 1-D coupled model GOTM-NORWECOM with Gaussian anamorphosis extensions of the deterministic ensemble Kalman filter (DEnKF).
Revised: 18 Jun 2012 – Accepted: 28 Jun 2012 – Published: 08 Aug 2012
Simon, E., Samuelsen, A., Bertino, L., and Dumont, D.: Estimation of positive sum-to-one constrained zooplankton grazing preferences with the DEnKF: a twin experiment, Ocean Sci., 8, 587-602, doi:10.5194/os-8-587-2012, 2012.