FAQs - BOM BARPA (py18)

I cannot see the BARRA2 local file paths from Gadi or ARE? 

Please check that you have registered for the relevant BARRA2 project code as local file paths are only visible to registered project members. You can check your registration status from MyNCI User Portal. 

If you are registered but having trouble from a Gadi job, please check that you have included the relevant data collection code(s) in the PBSPro storage directive of your job submission script, e.g.,

#PBS -l storage=gdata/ob53

What dataset/variables are available in the NCI collection?

Please refer to BARPA Parameter Descriptions.

You can also browse the full BARRA2 holdings in the NCI Data Catalogue.

What is the format of the data sets?

It is netCDF-4 classic. It is a community standard for sharing scientific data. Please refer to more information on netCDF.

How are the data sets organised?

The directory and file structures are as follows:

/g/data/py18
   |-- <product>
     |-- <nature of data> or <project_id>
        |-- <MIP-era>
             |-- <activity_id>
                  |-- <domain_id>
                       |-- <RCM-institution_id>
                            |-- <driving_source_id>
                                 |-- <driving_experiment_id>
                                      |-- <driving_variant_label>
                                           |-- <source_id>
                                                |-- <version_realisation>
                                                     |-- <freq>
                                                          |-- <variable_id>
                                                              |-- <version>
                                                                   |-- <netcdf filename>

When accessing the data on the THREDDS server, ignore the parent directory structure "/g/data/py18"

Example is,

/g/data/py18/BARPA/output/CMIP6/DD/AUS-15/BOM/ACCESS-CM2/historical/r4i1p1f1/BARPA-R/v1-r1/1hr/tasmax/latest/tasmax_AUS-15_ACCESS-CM2_historical_r4i1p1f1_BOM_BARPA-R_v1-r1_1hr_200501-200512.nc

Why is the dataset/variable I am after not available in the NCI collection?

Please check it is a modelling output of BARPA. For BARPA-R, please refer to Appendix of Su et al. (2022), Bureau Research Report 069.

If it exists, the dataset/variable is stored on tape archive and a request can be made to the Bureau of Meteorology. Please email help@nci.org.au (Subject: BARRA2 data collection).

What if I find an error or issue with the data? 

If you notice an issue within the NCI replica collection, please email help@nci.org.au (Subject: BARPA data collection). NCI will check if it is a local issue or can assist with reporting the issue upstream to Bureau of Meteorology. Details of any issues affecting local usage will be added to this page.

Where can I find metadata information?

The BARPA data files are stored in netCDF format, containing global attributes that inform how the files are being produced and variable-level attributes that inform how to interpret a variable. Most of the BARRA2 modelling variables are mapped onto the CORDEX-CMIP6 variable names.

For description of each parameter, please refer to BARPA Parameter Descriptions.

How many pressure levels are available?

Datasets for air temperature (ta*), zonal wind (ua*), meridional wind (va*), vertical wind (wa/wap*), geopotential heights (zg*), and specific humidity (hus*) are available for multiple pressure levels. The data for the pressure levels closer to the surface are provided as 1-hourly grids, while the data for pressure levels further up the atmosphere as 3-hourly grids. 

Specifically, the pressure levels available for BARPA-R (AUS-15) are,

• 6-hourly (6hr): 1000, 950, 925, 850, 700, 600, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, and 10 hPa (18 levels).

The pressure levels available for BARPA-C (AUST-04) are,

• 3-hourly (3hr): 1000, 975, 950, 925, 900, 850, 800, 750, 700, 600, 500, 400, 300, 200 hPa (14 levels). 
• 6-hourly (6hr): 250, 150, 100, 70, 50, 30, 20, 10 hPa (8 levels).

Please refer to BARPA Parameter Descriptions for a list of available variables and descriptions.

How to distinguish between time-instantaneous and time-aggregated variables, and interpret 'cell_method' in the netCDF files?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence

How to interpret instantaneous wind components data?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence

How to interpret maximum wind gust data?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence

How can I download the netcdf files?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence

What are the spatial extents of the data?

The BARPA data is available across a number of spatial domains, which are distinguished by different "domain_id", see the table below.

The "domain_id" is constructed in two parts XXX-YY(i), where XXX indicates domain extent and YYY indicates the grid resolution. There is an optional "i" to indicate that the data is on an interpolated grid, i.e., not the native modelling grid.

What is the projection datum of the data?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence

Is any of the data bias corrected against observational datasets?

Bias corrected BARPA-R data is organised in a different data collection. In that collection, the data for several commonly used surface variables was regridded to a regular 0.05 degree (~5 km) latitude-longitude grid across Australia, and calibrated against two observational datasets using two different bias correction methods.

What if I cannot find meteorological variables I want in this data?

Please refer to FAQs - BOM BARRA2 (ob53) - NCI Data Collections & Publishing - Opus - NCI Confluence