= PDAFomi_store_obs_l_index_vdist =

This page documents the routine `PDAFomi_store_obs_l_index_vdist` of PDAF-OMI.

This routine is used for the case that a user implements a user-provided alternative for the routine `PDAFomi_init_dim_obs_l`, which initializes the local observation information for PDAF-OMI in `thisobs_l` for a single local analysis domain. This variant is only used for 2+1D factorized localization. For usualy localization the routine [wiki:PDAFomi_store_obs_l_index] is used.

The routine can to be called in `init_dim_obs_l_OBSTYPE` in each observation module if a domain-localized filter (LESTKF/LETKF/LNETF/LSEIK/LKNETF)is used. 

|| See the [wiki:OMI_search_local_observations page on user-provided initialization of local observations] for the full description of a user-provided routine to intialize local observations. ||

The interface is:
{{{
  SUBROUTINE PDAFomi_store_obs_l_index_vdist(thisobs_l, idx, id_obs_l, distance, &
       cradius_l, sradius_l, vdist)

    TYPE(obs_l), INTENT(inout) :: thisobs_l  ! Data type with local observation
    INTEGER, INTENT(in) :: idx               ! Element of local observation array to be filled
    INTEGER, INTENT(in) :: id_obs_l          ! Index of local observation in full observation array
    REAL, INTENT(in) :: distance             ! Distance between local analysis domain and observation
    REAL, INTENT(in) :: cradius_l            ! cut-off radius for this local observation 
                                             !  (directional radius in case of non-isotropic localization)
    REAL, INTENT(in) :: sradius_l            ! support radius for this local observation
                                             !  (directional radius in case of non-isotropic localization)
    REAL, INTENT(in) :: vdist                ! support radius in vertical direction for 2+1D factorized

}}}

'''Notes:'''
 * `idx` is usually the counte over the valid local observation of the observation type in the observation module
 * `cradius_l` and `sradius_l` are directional radii, i.e. they are computed depending the direction between local analysis domain and observation, if a non-isotropic horizontal localization is used
 * While using this routine can be more convenient than doing the initialization of the variables in `thisobs_l` in the user code, in our tests the code ran faster when we did not use this routine, but did this initialization in the user code.