Changes between Initial Version and Version 1 of U_obs_op_lin


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Timestamp:
Dec 9, 2021, 3:16:23 PM (2 years ago)
Author:
lnerger
Comment:

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  • U_obs_op_lin

    v1 v1  
     1= U_obs_op_lin =
     2
     3The page document the user-supplied call-back routine `U_obs_op_lin`.
     4
     5The routine `U_obs_op_lin` is a call-back routine that has to be provided by the user. In the simplified interface the predefined name of the routine is `obs_op_lin_pdaf`, but in the full interface, the user can choose the name of the routine.
     6
     7The routine is used with the all 3D-Var methods. It has to perform the operation of the linearized observation operator acting on a state vector increment that is provided as `state_p`. The observed state has to be returned in `m_state_p`.
     8
     9The interface is the following:
     10{{{
     11SUBROUTINE obs_op_lin(step, dim_p, dim_obs_p, state_p, m_state_p)
     12
     13  INTEGER, INTENT(in) :: step               ! Current time step
     14  INTEGER, INTENT(in) :: dim_p              ! PE-local dimension of state
     15  INTEGER, INTENT(in) :: dim_obs_p          ! Dimension of observed state
     16  REAL, INTENT(in)    :: state_p(dim_p)     ! PE-local model state
     17  REAL, INTENT(out) :: m_state_p(dim_obs_p) ! PE-local observed state
     18}}}
     19
     20The routine is called during the analysis step. It has to perform the operation of the linearized observation operator acting on a state vector increment that is provided as `state_p`. The observed state has to be returned in `m_state_p`.
     21
     22Hints:
     23 * For a model using domain decomposition, the operation is on the PE-local sub-domain of the model and has to provide the observed sub-state for the PE-local domain.
     24 * If the observation operator involves a global operation, e.g. some global integration, while using domain-decomposition one has to gather the information from the other model domains using MPI communication.