Estimation of positive sum-to-one constrained zooplankton grazing preferences with the DEnKF: a twin experiment

[摘要] We consider the estimation of the grazing preferences parameters ofzooplankton in ocean ecosystem models with ensemble-based Kalman filters.These parameters are introduced to model the relative diet composition ofzooplankton that consists of phytoplankton, small size-classes of zooplanktonand detritus. They are positive values and their sum is equal to one.However, the sum-to-one constraint cannot be guaranteed by ensemble-basedKalman filters when parameters are bounded. Therefore, a reformulation of theparameterization is proposed. We investigate two types of variabletransformations for the estimation of positive sum-to-one constrainedparameters that lead to the estimation of a new set of parameters with normalor bounded distributions. These transformations are illustrated and discussedwith twin experiments performed with the 1-D coupled model GOTM-NORWECOM withGaussian anamorphosis extensions of the deterministic ensemble Kalman filter(DEnKF).

[学科分类] 海洋学与技术