= PDAFomi_localize_covar =

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

The routine has to be called in `localize_covar_OBTYPE` in each observation module if the localize EnKF is used. It applies the covariance localization.

|| See the [wiki:OMI_observation_modules page describing PDAF-OMI observation modules] for the full documentation of OMI observation modules and the [wiki:ImplementAnalysislenkfOmi page on implementing the analysis step of the LEnKF].||

The interface is:
{{{
  SUBROUTINE PDAFomi_localize_covar(thisobs, dim,  locweight, lradius, sradius, &
       coords, HP, HPH)

    TYPE(obs_f), INTENT(in) :: thisobs    ! Data type with full observation
    INTEGER, INTENT(in) :: dim            ! State dimension
    INTEGER, INTENT(in) :: locweight      ! Localization weight type
    REAL, INTENT(in)    :: lradius        ! localization radius
    REAL, INTENT(in)    :: sradius        ! support radius for weight functions
    REAL, INTENT(in)    :: coords(:,:)    ! Coordinates of state vector elements
    REAL, INTENT(inout) :: HP(:, :)       ! Matrix HP, dimension (nobs, dim)
    REAL, INTENT(inout) :: HPH(:, :)      ! Matrix HPH, dimension (nobs, nobs)
}}}

'''Notes:'''
 * The routine allows to specify the localization radius and support radius (`lradius`, `sradius`) and localization function (`locweight`) individually for each observation type. 
 * The coordinate array `coords` has to be filled consistently with the observation coordinates speified in `init_dim_obs_OBSTYPE`.
 * The routine only supports a fixed localization radius throughout the domain