Abstract
This paper is a contribution to the exploration of the parametric Kalman
filter (PKF), which is an approximation of the Kalman filter, where the
error covariance are approximated by a covariance model. Here we focus
on the covariance model parameterized from the variance and the
anisotropy of the local correlations, and whose parameters dynamics
provides a proxy for the full error-covariance dynamics. For this
covariance mode, we aim to provide the boundary condition to specify in
the prediction of PKF for bounded domains, focusing on Dirichlet and
Neumann conditions when they are prescribed for the physical dynamics.
An ensemble validation is proposed for the transport equation and for
the heterogeneous diffusion equations over a bounded 1D domain. This
ensemble validation requires to specify the auto-correlation time-scale
needed to populate boundary perturbation that leads to prescribed
uncertainty characteristics. The numerical simulations show that the PKF
is able to reproduce the uncertainty diagnosed from the ensemble of
forecast appropriately perturbed on the boundaries, which show the
ability of the PKF to handle boundaries in the prediction of the
uncertainties. It results that Dirichlet condition on the physical
dynamics implies Dirichlet condition on the variance and on the
anisotropy.