= `init_obs_pdaf`=

The page document the user-supplied call-back routine `init_obs_pdaf`.

The routine `init_obs_pdaf` (called `U_init_obs` inside the PDAF core routines) is a call-back routine that has to be provided by the user. The routine is used with all global filters. The routine is called during the filter analysis step. When the routine is called PDAF provides an array for the vector of observation, which needs to be filled with the observation values in this routine.

The interface is the following:
{{{
SUBROUTINE init_obs(step, dim_obs_p, observation_p)
}}}
with
 * `step` : `integer, intent(in)`[[BR]] Current time step
 * `dim_obs_p` : `integer, intent(in)`[[BR]] Size of the observation vector
 * `observation_p` : `real, intent(out), dimension(dim_obs_p)`[[BR]] Vector of observations

Note:
 * For a model using domain decomposition, `observation_p` is the vector of observations that exist on the model sub-domain for the calling process.