ACCESS-DN: Hybrid-height (all-lvls) "geopht" fields

Model summary

ACCESS-C DARWIN covers the Darwin 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:

IDY25405.APS3.geopht.all-lvls.YYYYMMDDHH.HHH.model.grb2 or IDY25405.APS3.geopht.all-lvls.YYYYMMDDHH.HHH.model.nc4

Horizontal grid geometries

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.

Vertical levels

Eta-level index values:

1 to 80 by 1

All fields lie on eta "theta" levels.
Refer to Appendix B for more information.

Time steps

Forecast hours of multi-level fields:

0

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.

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

Appendix B - Hybrid Height Levels

Notes:

• [theta] and [rho] denote the level types on which the parameters A and B are valid.

• A values represent the height of the hybrid levels above the geoid assuming zero topography.

• B values represent the fraction of the topographic height included in the hybrid levels.

• The height of a hybrid-height level (m) can be calculated via:

  z(k, i, j) = A(k) + B(k)*topo(i, j)
  where k denotes the level index,
  z(k, i, j) is the height above the geoid at grid-point (i, j, k),
  topo(i, j) is the height of the surface above the geoid at (i, j) and
  A(k) & B(k) are the values of A and B at level k.