Grid File ID Codes

§ Only runs for active named Tropical Cyclones. The order is determined by priority, and which tropical cyclone runs for each domain can vary from cycle to cycle.

Field descriptors

Level group descriptors

Grid-coordinate descriptors

§ Note: The raw ACCESS outputs are actually on a set of interleaved ("staggered") grids. To achieve a uniform grid for all parameters the wind components have been interpolated horizontally (and vertically in the case of theta level outputs).

Single-level data

Single-level data is provided separately from other level-types. This data can be used in conjunction with data from any of the other multi-level files (model or pressure-level) since the horizontal grid is consistent with the horizontal layout of each of these formats.

Note: single level products also include rho-level-2 and rho-level-4 products described in the "Data on hybrid-height levels" table below.

Data on hybrid-height levels (model levels)

This data-set consists of ACCESS fields valid on all 70 ACCESS hybrid-height levels for ACCESS-G, and all 80 ACCESS hybrid-height levels for ACCESS-C.

Data on pressure-levels

This data-set consists of ACCESS fields interpolated to 35 pressure levels (a super-set of the "standard" pressure levels). Physically constrained extrapolations are performed when required (e.g. when deriving data at 1000hPa for a location where surface pressure is 990hPa). The interpolation method used is a tri-linear mapping between native model coordinate space and logarithmic pressure-levels.

Notes on specific NWP file-formats

Data files are made available in two formats, GRIB2 and NetCDF4. Metadata for certain fields has changed with APS3. For details along with technical information about the formats, please refer to GRIB2 format notes and NetCDF format notes.

Main APS3 differences

• The ACCESS-R model will not be a part of the APS3 suite as it has been superseded by ACCESS-G.
• Product codes IDY25006 and IDY25026 are new. Products with these codes are intended to replace APS2 ACCESS-R products with product codes IDY25300 and IDY25320 respectively. Grid resolution is as per IDY25000 (i.e. approximately 12 km in the mid latitudes).
• All domains of ACCESS-C, except VicTas, have been enlarged.
• APS3 ACCESS-C models have 80 vertical levels, whereas APS2 only had 70, and now goes up to 38500m instead of 40000m.
• Hourly minimum, maximum and average fields are not available at the first (analysis) time-step in APS3 ACCESS-C model outputs. This is due to ACCESS-C performing its own data assimiliation process with a window that starts 30 minutes prior to the nominal analysis time.
• New fields "synthetic infrared satellite brightness temperature (K)" and "synthetic water vapour satellite brightness temperature (K)" are available.
• Single-level forecast fields are now available at hourly temporal resolution for ACCESS-G.
• In APS3 ACCESS-G the time interval over which time-averaged fields are calculated is now hourly instead of 3-hourly as in APS2. Maximum and minimum screen-level temperature fields are similarly affected.
• The fields "accumulated convective precipitation (kg m-2)" and "accumulated large scale precipitation (kg m-2)" in APS2 were labelled incorrectly. The field descriptions and accompanying metadata have been amended to be "accumulated convective rainfall (kg m-2)" and "accumulated large scale rainfall (kg m-2)" respectively.
• Subsurface layer depth metadata values for soil temperature and soil moisture content fields were found to be incorrect in APS2 and have been corrected in APS3.
• The field "summed evaporation over open sea" from APS2 has been replaced by "average rate of evaporation over open sea (kg m-2 s-1)".
• The description of the ACCESS-G field "roughness length" has been clarified as "surface roughness length for momentum (m)". In APS2 the ACCESS-R "roughness length" field was found to represent a different field (a roughness length quantity over the ocean) and this variant is deprecated, replaced with the ACCESS-G "surface roughness length for momentum (m)" valid over both land and sea.