ROPP_1DVAR Error Correlations for release version v10.0
------------------------------------------------------

This directory contains a collection of error correlation files and scripts 
which users may find helpful for setting up input to ROPP_1DVAR tools. 
Further details are provided in the ROPP User Guide (Part II).

N.B. The ROPP FM and 1DVAR routines assume input data are in ascending height
     order (i.e. array index 1 nearest surface). The required error correlation
     and covariance structures must therefore be also defined in this way.

Notes on the Fortran program files in this directory:

ropp_1dvar_add_bgr_error.f90        - Tool to add background pressure, temperature 
                                      and humidity error values to a ROPP format 
                                      netCDF file. Errors are read from the 'sigma'
                                      variable in an input background covariance
                                      matrix file.

ropp_1dvar_add_refrac_error.f90     - Tool to add refractivity observation error
                                      values to a ROPP netCDF file. A number of 
                                      different error models may be chosen. 
                                      Type 'ropp_1dvar_add_refrac_error -h' for
                                      further details.

ropp_1dvar_add_bangle_error.f90     - Tool to add bending angle observation error
                                      values to a ROPP netCDF file. A number of 
                                      different error models may be chosen. 
                                      Type 'ropp_1dvar_add_bangle_error -h' for
                                      further details.

Notes on the data files in this directory:

ropp_bg_ecmwf_error_corr_L91.nc     - Background error correlation matrix in packed
                                      form for the latest ECMWF model structure 
                                      (91 levels). This file is suitable for input 
                                      to the ROPP_1DVAR tools using '--bg-corr'
                                      command line option with ECMWF backgrounds.
                                      It is recommended that 1dVar tools are run 
                                      with bg_covar_method = VSFC config option.

ropp_bg_grassaf_ecmwf_error_corr_L91.nc - Variation on the above.

ropp_bg_meto_error_corr_L70.nc      - Background error correlation matrix in packed
                                      form for the latest Met Office model 
                                      structure (70 levels). This file is suitable 
                                      for input to the ROPP_1DVAR tools using 
                                      '--bg-corr' command line option with Met 
                                      Office backgrounds.
                                      It is recommended that 1dVar tools are run 
                                      with bg_covar_method = VSFC config option.

ropp_bg_ecmwf_error_corr_L60.nc     - Background error correlation matrix in packed
                                      form for the previous ECMWF model structure 
                                      (60 levels). 
                                      It is recommended that 1dVar tools are run 
                                      with bg_covar_method = VSFC config option.

ropp_bg_meto_error_corr_L50.nc      - Background error correlation matrix in packed
                                      form for the previous Met Office model 
                                      structure (50 levels). This file is suitable 
                                      for input to the ROPP_1DVAR tools using 
                                      '--bg-corr' command line option with Met 
                                      Office backgrounds.
                                      It is recommended that 1dVar tools are run 
                                      with bg_covar_method = VSFC config option.

ropp_ob_refrac_error_corr_247.nc    - 247L refractivity observation correlation matrix
                                      in packed form. This file is suitable for 
                                      input to the ropp_1dvar_refrac tool using 
                                      '--obs-corr' command line option. 
                                      It is recommended that 1dVar tools are run 
                                      with either obs_covar_method = VSDC or
                                      obs_covar_method = VSFC config options.

ropp_ob_bangle_error_corr_300L.nc   - 300L bending angle observation correlation matrix
                                      in packed form. This file is suitable for 
                                      input to the ropp_1dvar_bangle tool using 
                                      '--obs-corr' command line option. 
                                      It is recommended that 1dVar tools are run 
                                      with either obs_covar_method = VSDC or
                                      obs_covar_method = VSFC config options.
                                      The correlation matrix is diagonal.

ropp_ob_bangle_error_corr_247L.nc   - 247L bending angle observation correlation matrix
                                      in packed form. This file is suitable for 
                                      input to the ropp_1dvar_bangle tool using 
                                      '--obs-corr' command line option. 
                                      It is recommended that 1dVar tools are run 
                                      with either obs_covar_method = VSDC or
                                      obs_covar_method = VSFC config options.
                                      The correlation matrix is diagonal.

ropp_bg_ses_ecmwf_error_corr_L60.nc - 60L B-matrix generated by the Scaled
                                      Ensemble Standard Deviation method of
                                      Holm et al, ECMWF Tech Memo 680, 2012.
                                      Needs bg_covar_method = RSFC in the config file.

ropp_bg_ses_ecmwf_error_corr_L91.nc - 91L B-matrix generated by the Scaled
                                      Ensemble Standard Deviation method of
                                      Holm et al, ECMWF Tech Memo 680, 2012.
                                      Needs bg_covar_method = RSFC in the config file.

ropp_bg_ses_ecmwf_error_corr_L137.nc- 137L B-matrix generated by the Scaled
                                      Ensemble Standard Deviation method of
                                      Holm et al, ECMWF Tech Memo 680, 2012.
                                      Needs bg_covar_method = RSFC in the config file.

[N.B. It is generally assumed that bending angle observations are uncorrelated,
so it is recommended that the ropp_1dvar_bangle tool is run with errors 
specified with the VSDC configuration option.]


ROPP Development Team
Met Office

Version 10.0
30 September 2020



