DKRZ Quality Assurance Tool

The Quality Assurance (QA) software developed at the DKRZ tests the conformance of meta-data of climate simulations given in NetCDF format to conventions and rules of projects. Additionally, the QA checks time sequences of data, and the technical state of data (i.e. occurrences of Inf or NaN, gaps, replicated sub-sets, etc.) for atomic data set entities, i.e. variable and frequency, like tas and mon for monthly means of 'Near-Surface Air Temperature’. When the amount of data is subdivided into several files, then changes between these files in terms of (auxiliary) coordinate variables will be detected as well as gaps or overlapping time ranges. This may also apply to consecutive experiments.

At present, the QA checks data of the projects CMIP5 and CORDEX by consulting tables based on a controlled vocabularies and requirements provided by the projects. When such prior information is given about directory structures, format of file names, variables and attributes, geographical domain, etc., then any deviation from compliance will be annotated in the QA results.

Please, direct questions or comments to


The tool requires the BASH shell and a C/C++ compiler.


The tool is distributed in two versions:
  • QC-0.4
    Stable, used to operate checks of CMIP5 and CORDEX data.
    This QA software package is maintained with the version control tool subversion. The installation is done by script. Please, click install to download; the script is also located in the QC-0.4 package. Note that depending on the browser, the script could be saved as install.txt and perhaps without execute permission. If so, run bash install.txt (or chmod u+x install).
    After installation and configuration, QA checks are started on the command-line by: /package-path/scripts/qcManager [options]
  • QA-DKRZ, v.0.5-beta
    Development stage: the software resides on GitHub and is accessible by git clone .
    QA runs are started on the command-line by: /package-path/scripts/qa_DKRZ [options] .
    While former versions took for granted that the NetCDF Climate and Forecast (CF) Meta Data Conventions were held when specified, the conformance is now tested.
    The CF check is both embedded in the QA tool itself and provided by a stand-alone tool including a test suite of files.
    • CF Checker
      The CF Conformance checker applies to conventions 1.4 - 1.7draft. Note that it takes a few seconds for the installation when it runs for the first time.
      Command-line for the stand-alone tool: package-path/scripts/dkrz-cf-checker [options] [files]
      -C str CF conventions string; taken from global attributes by default.
      -F path Find all NetCDF files in the sub-dir tree starting at path.
      -p str Path to one or more NetCDF file; this is applied only to files without any path component.
      -R Apply also recommendations given in the CF conventions.
      -x str Path to QA-DKRZ/bin; required if the script was copied to the outside of
      the package (note that a symbolic link works without this option).
      --ts Run the CF Test Suite located within the package (file names may be given additionally).
  • CF Test Suite
    A collection of NetCDF files designed to cover all rules of the CF Conventions derived from the examples of the PDF documents. There are two branches:
    - PASS     Proper meta-data and data sets, which should never output a failure. No. of files: 81
    - FAIL     Each file contains a single break of a rule and should never pass the test. No. of files: 187

Note that the name of the tool has changed over the years as well as the name of the starting script. At first, the acronym QC (Quality Control/Check) was used, but was changed to the more commonly used term QA (Quality Assurance). The names qcManager, qc_DKRZ, and qa_DKRZ start an identical script (also, the underscore may be replaced by a hyphen). Option names containing QC or qc are still usable for backward compatibility.


  • A script install is provided to manage different installation/update modes.
  • install runs on linux utilising Bash and C/C++ (AIX works, too).
  • Environmental variables CC, CXX, CFLAGS, and CXXFLAGS are accepted.
  • install establishes access to libraries, which may be linked or built, as well as updating sources and executables.
  • A script snippet install_configure is installed during the first run of install. If option --build is not applied, then the user is notified to edit install_configure.
  • After the installation, compiler settings and paths to libraries are always read from install_configure.
  • Proceedings of installation/update are logged in file install.log.
  • The full set of options is described by ./install --help.
  • Compilation of executables: adding key-word CMIP5 to the call of install (CORDEX is the default) compiles for CMIP5.
  • A test-run is started automatically generating some results in the directory package-path/example/test_I.

Building libraries

          Command-line: ./install --build [options]


Updating QC/QA from the repository and re-compilation of executables is done easiest by using the install script. There are two modes: automatic and manual updates. Please note that the execution of package-path/install [project] does not call for any updates by default; this will only recompile locally changed C/C++ programs.

Manual Update

Command-line: package-path/install --up[date] [options]
This applies any changes in the repository. If C/C++ programs are affected, then executables are remade. Please note that libraries are not updated. If you want to do so, then you have to set option --build.

Automatic Update

          Command-line: package-path/install --auto-up [options]
  • Once --auto-up was set, the package will always be synchronised to the repository at the beginning of each QC/QA session, which is started by package-path/scripts/qa-DKRZ.
  • This mode may be disabled by option --auto-up=disable.
  • Enabling/disabling the auto-mode works also during operational runs of the qa-DKRZ script.
  • For QA-DKRZ, there is a daily search for updates of the required tables (area-type-table.xml, cf-standard-name-table.xml, standardized-region-names.html) from

QA Configuration

The QA would run basically on the command-line only with the specification of the target(s) to be checked. However, using options facilitates a check in particular for a given project.
Configuration options could be supplied on the command-line and by one or more conf-files. Configuration options follow a specific syntax with case-insensitive option names (e.g. KEY-WORD and kEy-WorD).

KEY-WORD enable key-word (equivalent to key-word=t)
KEY-WORD = value[,value ...] assign key-word a (comma-separated) value (overwrite)
KEY-WORD += value[,value ...] same, but append

Partitioning of data

The specification of a path to a directory tree by option PROJECT_DATA results in a check of every NetCDF files found within the entire tree. This can be further customised by the key-words SELECT and LOCK, which follow special rules.

KEY-WORD variable[, variable, ...] specified variables for every path; += mode for sub-paths
KEY-WORD path[,path,...] [=] all variables within the specified path; += mode for sub-paths
KEY-WORD path[,path,...] = [variable[, variable, ...] specified variables within the given paths; the = char in-between is mandatory; += mode for sub-paths
KEY-WORD = path[,path,...] = [variable[, variable, ...] same, but overwrite mode
KEY-WORD += path[,path,...] = [variable[, variable, ...] append to a previous assignment
  • Highest precedence is for options on the command-line.
  • If path has no leading '/', then the search is relative to the path specified by option PROJECT_DATA.
  • Special for options -S arg or an appended plain string on the command-line: cancellation of previous SELECTions in any configuration file.
  • If SELECTions are specified on the command-line (options -S) with an absolute path, i.e. beginning with '/', then PROJECT_DATA specified in any other config-files is cancelled..
  • All selections refer to the atomic data set of a given variable, i.e. all sub-temporal files; even if a file name is appended to a path.
  • Locking gets the higher precedence over selection.
  • Path and variable indicators are separated by the '=' character, which may be omitted when there is no variable (except the case that each of the paths contains no '/' character).
  • Regular expressions may be applied for both path(s) and variable(s).
  • If an expanded path points to a sub-dir tree, then this is searched for the variables.
  • A variable is selected if the expanded variable part fits the beginning of the name, e.g. specifying 'tas' would select all tas, tasmax, and tasmin files.
    Note that every file name begins with 'variable_...' for CMIP5/CORDEX, thus, use 'tas_' for this alone.

Configuration files

A description of the configuration options is given in the repository:
    QC-0.4:     /package-path/tables/SVN_defaults/"project-name"_qc.conf
    QA-DKRZ: /package-path/tables/projects/"project-name"/"project-name"_qa.conf

Configuration files and options may be specified multiply following a given precedence. This facilitates to have a file with short-term options (in a file attached to the -f option on the command-line), another one with settings to site-specific demands, which are robust against changes in the repository, and long-term default settings from the repository. All options may be specified on the command-line plus some more (/package-path/QA-DKRZ/scripts/qa_DKRZ --help and /package-path/QC_0.4/scripts/qcManager --help, respectively).
A sequence of configuration files is accomplished by QA_CONF=conf-file assignments embedded in the configuration files (nesting depth is unrestricted). The precedence of configuration files/options is given below from highest to lowest.
  • directly on the command-line
  • in the task-file (-f file) specified on the command-line.
  • QA_CONF assignments embedded (descending starts from the -f file).
  • site-specific files provided by files located straight in /package-path/tables.
  • defaults for the entire project:
    QC-0.4:     /package-path/tables/SVN_defaults.
    QA-DKRZ: /package-path/tables/projects/ project-name.


Any failed QA test raises an annotation. In fact, testing and issuing annotations are different processes. The way of testing is done always by the program; the user has no influence. However, issuing annotations is controlled by the user by means of configuration options and the check-list table. Location:
QC-0.4:     /package-path/tables/SVN_defaults/ project-name_check-list.conf.
QA-DKRZ: /package-path/tables/projects/ _project-name_check-list.conf
and CF_check-list.conf.

A check may-be discarded entirely or for specified variables. Also, specific data values of given variables may be excluded from annotating. Details are explained in the check-list files.

QA Results

Log-files and annotations are written to the location specified by the configuration option QA_RESULTS. Check results of data files are grouped in directories or files based on the options beginning with the token EXP. The purpose of such an experiment-like name is to tag a larger set of various checks with a name that corresponds to a certain volume of netCDF files. There are several ways to define a name with the precedence of the following options: explicit EXP_NAME=string, a pattern common to file names (EXP_FNAME_PATTERN), components of paths common to the ensemble (EXP_PATH_INDEX), and the default name 'all-scope'.
In general, five sub-directories are created:
  • check_logs (directory)
    • exp-like-name.log (file)
      The files are written in the human-readable YAML format (optional for QC-0.4 by YAML in the configuration or --yaml on the command-line; there are tools, which transform YAML coding into XML). Each entry of a log-file represents the check of a (sub-temporal) data file regardless of whether annotations were issued or not.
    • Annotations.yaml Only log-file entries having annotations are extracted.
      QC-0.4:     the name of the directory is _Notes; not created when there are no annotations.
    • _Periods (directory)
      CORDEX for instance, does not prescribe the periods of atomic data sets, i.e. the time interval from the beginning of the first sub-temporal file to the end of the last one. The period of each variable, grouped by frequencies, is tabled in files with experiment-like names.
    • Summary (directory)
      A directory with sub-directories of exp-like names containing human-readable files. All annotations are listed in the file annotations.txt as well as differing periods. Also, files are created for each annotation type.
  • cs_table (directory; optional)
    This directory is created if the option CHECKSUM is enabled. Files with experiment-like names contain entries for each checked file consisting of a checksum (md5 by default, but any other system may be bound), creation_date, and tracking_id; the latter two only if corresponding global attributes exist. This information is used to raise an annotation, if later versions of the same file name apply identical creation_date or tracking_id attributes.
  • data (directory tree)
    Mostly for internal use. The directory structure of the data file ensemble is reproduced containing lock-files or atomic NetCDF files with the checksum of the original data for each time value.
  • session_logs (directory)
    Internal use
  • tables (directory)
    All tables and configuration files used for a specific check.

Best Practise


  1. Get sources
    QC-0.4: download the script 'install'
    QA-DKRZ: git clone
  2. Create install_configure
        if the NetCDF-4 library with HDF5 support is available: ./install
        if supported libs should be protected against deletion (by hard-links): ./install --link=path
        if NetCDF libs have to be built: ./install --build
  3. Edit file install_configure
  4. Optional: Verify installation success: ./install --show-inst
  5. Make executables: ./install [PROJECT]
    Note that this performs a test run with results in /package-path/example/test_I


Most of the configuration option have a useful default and some options only for very specific conditions occurring at different sites.

  • Use configuration options on the command-line only for testing or re-checking a small set of data.
  • Use a task-file for frequently modified directives, which names a QA/QC_conf file.
  • PROJECT_DATA should only contain a site specific path to the data set, e.g. PROJECT_DATA=/path/data/CORDEX .
  • Use the SELECT option for partitioning the amount of data to be checked. E.g. SELECT AFR-44 would check the data of every model available for the specified domain of CORDEX data.
    On the other hand, SELECT '.*/historical=orog' would find any orography file in all historical in the given PROJECT_DATA=sub-dir-tree.
  • Option EXP_PATH_INDEX is for partitioning the results in QC_RESULTS/check_logs. Please choose unique names among the total path components to data.
    E.g. let the path be /path 10 /AFR-44 9 /SMHI 8 /CCCma-CanESM2 7 /historical 6 /r1i1p1 5 /SMHI-RCA4 4 /v1 3 /day 2 /clh 1 , index given by subscripts is only for illustration, and have EXP_PATH_INDEX=9,8,7,6,5,3 , then the resulting name would be AFR-44_SMHI_CCCma-CanESM2_historical_r1i1p1_v1 .
  • Similarly, PT_PATH_INDEX defines the name of a project table, which is created and utilised to check consistency across sub-temporal files of a given variable; _PT_PATH_INDEX_=9,8,7,4 by default for CORDEX, e.g. _AFR-44_SMHI_CCCma-CanESM2_SMHI-RCA4, which is consulted for all similar experiments and versions.
  • The CORDEX_check-list.conf file provides directives, how issue annotations. If a level of severity higher than L2 was rated, then a QA/QC session may stop. The option NOTE_LEVEL_LIMIT=1 would prevent any interruption.

Operational Mode:

Before starting to check data, please make sure that everything was set properly:
  • Command-line: /package-path/scripts/qa_DKRZ -f file -e_show_conf
    Inspect the configuration options displayed on the screen.
  • Command-line: /package-path/scripts/qa_DKRZ -f file -e_show_exp
    Path and and filename of every SELECTed item will be displayed below the executed command-line call. Searching the data base may take a somewhat long time, depending on the amount of data.
  • Command-line: /package-path/scripts/qa_DKRZ -f file -E_next
    Only the first path-variable resulting from the SELECT evaluation will be checked. If everything appears fine in folder QA_RESULTS/check_logs, then restart the call without e_next. This will resume the session.
  • Use nohup for long-term execution in the background. If the script is run in the foreground, then command-line option -m may be helpful by showing the current file name under investigation on a status-line below the script call.
  • Examine the QA results in directory QA_RESULTS/check_logs. Human-readable annotations are given in sub-directory Summary.
  • Manual termination of a session: if an immediate break is required, please inquire the process-id (pid), e.g. by ps -ef, and execute the command kill -TERM pid. This will close the current session neatly leaving no remnants.