|  | 1 | = init_obsvars_pdaf = | 
          
            |  | 2 |  | 
          
            |  | 3 | The page documents the user-supplied call-back routine `init_obsvars_pdaf`, which was introduced with PDAF V3.0. | 
          
            |  | 4 |  | 
          
            |  | 5 | The routine `init_obsvars_pdaf` (named `U_init_obsvars` inside PDAF) is a call-back routine that has to be provided by the user. | 
          
            |  | 6 | The routine is used only with the ENSRF/EAKF. The routine is called by PDAF during the analysis step and has to provide the filter with a vector of observation error variances. | 
          
            |  | 7 |  | 
          
            |  | 8 | The interface is the following: | 
          
            |  | 9 | {{{ | 
          
            |  | 10 | SUBROUTINE init_obsvars_pdaf(step, dim_obs_f, var_f) | 
          
            |  | 11 | }}} | 
          
            |  | 12 | with arguments: | 
          
            |  | 13 | {{{ | 
          
            |  | 14 | INTEGER, INTENT(in) :: step           ! Current time step | 
          
            |  | 15 | INTEGER, INTENT(in) :: dim_obs_f      ! Dimension of full observation vector | 
          
            |  | 16 | REAL, INTENT(out) :: var_f(dim_obs_f) ! vector of observation error variances | 
          
            |  | 17 | }}} | 
          
            |  | 18 |  | 
          
            |  | 19 | The variance vector `var_f` is for the full observation vector. | 
          
            |  | 20 |  |