Changes between Initial Version and Version 1 of U_obs_op_adj

Timestamp:

Dec 9, 2021, 3:20:20 PM (3 years ago)

Author:

lnerger

Comment:

--

U_obs_op_adj

@@ +1 @@
+= U_obs_op_adj = 
+
+The page document the user-supplied call-back routine `U_obs_op_adj`.
+
+The routine `U_obs_op_adj` 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_adj_pdaf`, but in the full interface, the user can choose the name of the routine.
+
+The routine is used with the all 3D-Var methods. It has to perform the operation of the adjoint observation operator. It has to perform the operation of the adjoint observation operator. The operator acts on a vector in observation space that is provided as m_state_p. The resulting state vector has to be returned in `state_p`.
+
+The interface is the following:
+{{{
+SUBROUTINE U_obs_op_adj(step, dim_p, dim_obs_p, state_p, m_state_p)
+
+  INTEGER, INTENT(in) :: step                 ! Current time step
+  INTEGER, INTENT(in) :: dim_p                ! PE-local dimension of state
+  INTEGER, INTENT(in) :: dim_obs_p            ! Dimension of observed state
+  REAL, INTENT(in)    :: m_state_p(dim_obs_p) ! PE-local observed state
+  REAL, INTENT(out)   :: state_p(dim_p)       ! PE-local model state
+}}}
+
+Hints:
+ * 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.
+ * 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.