ACCESS-BN: single-level "group2" fields
A number of raw and post-processed NWP products are available as outputs from the Australian Community Climate Earth-System Simulator (ACCESS) suite of Numerical Weather Prediction models which are run routinely by the Bureau National Operations Centre (NOC). This document describes the content of the ACCESS-C BRISBANE (version APS3) IDY25402.APS3.group2.slv.YYYYMMDDHH.HHH.surface and IDY25422.APS3.group2.slv.YYYYMMDDHH.HHH.surface series of products.
For background information about ACCESS please refer to the top-level ACCESS NWP technical data documentation page.
If you require further information or assistance about ACCESS NWP products contact the Bureau's Real-time Data Services Section.
Model summary
ACCESS-C BRISBANE covers the South-East QLD domain, has a resolution of about 1.5 km and is run four times per day (00Z, 06Z, 12Z & 18Z basetimes) out to a forecast hour (HHH) of +36 (+42 for 18Z). This model is nested in the ACCESS-G model and consists of both an assimilation and forecast component.
NWP data filename convention
All NWP files in this product series have names that conform to the following convention:
IDY25402.APS3.group2.slv.YYYYMMDDHH.HHH.surface.grb2 or IDY25402.APS3.group2.slv.YYYYMMDDHH.HHH.surface.nc4 or
IDY25422.APS3.group2.slv.YYYYMMDDHH.HHH.surface.grb2 or IDY25422.APS3.group2.slv.YYYYMMDDHH.HHH.surface.nc4
where
YYYYMMDDHH | Base-date of model run in UTC time. YYYY = year, MM = month, DD = day, HH = hour |
---|---|
HHH | Forecast hour. A HHH of 000 is the analysis time-step. |
Horizontal grid geometries
Variant
[IDY code]
|
Resolution
[Lon x Lat]
|
Domain limits
[W to E, S to N (Lon x Lat grid points)]
|
Parameters
[NC Vars]
|
---|---|---|---|
IDY25402
|
0.014 by 0.013 | 145.000 to 157.029, -31.500 to -21.470 (892 x 744) | All |
IDY25422
|
0.014 by 0.013 | 145.000 to 157.029, -31.500 to -21.470 (892 x 744) | All |
Please note that
- Latitude values in GRIB and NetCDF files are ordered North to South while longitude values are ordered West to East.
- Longitudes always lie in the range 0.0 to 360.0 degrees. Longitudes can be transformed to lie between -180 and +180 degrees by subtracting 360 degrees from any longitude values greater than 180.
Time steps
- Forecast hours of single-level fields:
- 0 to 36 by 1
Parameters
The following fields are included in this product series. Note that the "G2 d.c.n" table column refers to a field's GRIB2 'discipline'.'parameterCategory'.'parameterNumber' metadata. For more information see GRIB2 format notes.
Single-level fields
G2 d.c.n | NetCDF var | Steps | G2 Units | NC Units | Description |
---|---|---|---|---|---|
0.2.22 | wndgust10m | All | m s-1 | m s-1 | 10m wind gust |
0.1.6 | accum_evap | All | kg m-2 | kg m-2 | Accumulated evaporation from land soil surface |
0.1.206 | av_evap_sea | 1... | kg m-2 s-1 | kg m-2 s-1 | Average rate of evaporation over open sea |
0.6.32 | fog_fraction | All | Numeric | 1 | Fog fraction |
0.6.5 | hi_cld | All | % | 1 | High cloud cover |
0.19.0 | vis_precip | All | m | m | Horizontal visibility (incl precip) |
0.6.3 | low_cld | All | % | 1 | Low cloud cover |
0.6.4 | mid_cld | All | % | 1 | Middle cloud cover |
0.3.18 | abl_ht | All | m | m | Planetary boundary layer height |
0.1.3 | precwtr | All | kg m-2 | kg m-2 | Precipitable water |
2.0.3 | soil_mois | All | kg m-2 | kg m-2 | Soil moisture content in a layer |
Explanation of steps column terms
All | Parameter available at all time-steps |
---|---|
All but steps | Parameter available at all time-steps except as specified |
hhh... | Parameter available from fhr onward |
Notes on specific NWP file-formats
For technical notes about the GRIB2 encoding of ACCESS data, please refer to GRIB2 format notes. For technical notes about the NetCDF4 encoding of ACCESS data, please refer to NetCDF format notes.
Appendix A - Extended Field Descriptions
Extended description of single-level fields
G2 d.c.n | NetCDF var | Detailed description |
---|---|---|
0.2.22 | wndgust10m | Maximum three second wind speed (wind gust) at 10m above ground level. [m s-1] |
0.1.6 | accum_evap | Accumulated evaporation from land soil surface. [kg m-2] |
0.1.206 | av_evap_sea | Time-averaged rate of evaporation over open sea. [kg m-2 s-1] |
0.6.32 | fog_fraction | Estimated fog fraction at 1.5m above ground level. Please note that this diagnostic has not be tuned for Australian conditions and does not include dynamic atmospheric particulate densities, which is an important part of the algorithm used to generate this field. At this stage this field is considered experimental and should be used with due caution. [1] |
0.6.5 | hi_cld | High cloud cover, calculated under maximum overlap assumption between ICAO 500hPa and 150hPa levels (5574m and 13608m above mean sea level). [1] |
0.19.0 | vis_precip | Estimated horizontal visibility at approximately 1.5m above ground level, including reduction due to precipitation. Calculated similarly to grib code 20.229. At this stage this field is considered experimental and should be used with due caution. [m] |
0.6.3 | low_cld | Low cloud cover, calculated under maximum overlap assumption between ICAO 1000hPa and 800Pa levels (111m and 1949m above mean sea level). [1] |
0.6.4 | mid_cld | Middle cloud cover, calculated under maximum overlap assumption between ICAO 800hPa and 500Pa levels (1949m and 5574m above mean sea level). [1] |
0.3.18 | abl_ht | Height above ground level of the top of the planetary boundary layer (i.e. boundary layer depth). [m] |
0.1.3 | precwtr | Total column precipitable water. [kg m-2] |
2.0.3 | soil_mois | Total (frozen and unfrozen) soil moisture content in soil layer 1 (surface to 0.1m depth). [kg m-2] |
Please note:
- Fields in the above tables are listed in the same order as shown in the Parameters section of this document.
- Units in the above table refer to NetCDF fields. In some cases the GRIB2 equivalent field has had values scaled/offset to convert to SI units for WMO GRIB2 compliance.
- The nature of fields can not always be deduced easily from their NetCDF variable names. It is always safest to refer to the detailed description of a parameter.
- All accumulated fields are accumulated from the start of the model assimilation window. Hence any of these fields can be non-zero at the model base-time (which is a time-step at the center of the assimilation window).