  Variational data assimilation technique applied to identification of optimal
approximations of derivatives near boundary is discussed in frames of
one-dimensional wave equation. Simplicity of the equation and of its numerical
scheme allows us to discuss in detail as the development of the adjoint model
and assimilation results. It is shown what kind of errors can be corrected by
this control and how these errors are corrected. This study is carried out in
view of using this control to identify optimal numerical schemes in coastal
regions of ocean models.
