Available ACCESS-based models

All of the ACCESS models have recently been upgraded from version APS1 to APS2. APS2 models assimilate more observational inputs and include improved model physics. APS2 ACCESS-G and city systems are also cofigured to run at higher horizontal spatial resolution compared to APS1.

The following table describes the APS2 family of models.

§ ACCESS-C consists of a set of models covering domains around Sydney, Victoria and Tasmania, Brisbane, Perth, Adelaide and Darwin.

The AUSWAVE model was also upgraded to align with the ACCESS APS2 upgrades. Information about the products available from this system can be found here.

NWP data products

A range of NWP products, available via FTP for Registered Users, has been made available in NetCDF4 and GRIB edition 2 formats.

The ACCESS models output meteorological parameters defined on three-dimensional grids for each forecast time-step. The grid structure is evenly spaced latitude/longitude in the horizontal and hybrid-height based in the vertical (where vertical is with respect to the mean-sea-level surface). As such the NetCDF and GRIB file products contain a range of gridded field values valid for a particular model time-step.

In addition to the native ACCESS model hybrid-height coordinates, data on pressure-levels (levels of constant atmospheric pressure) is also available. Note that data on these extra level types is derived entirely from the hybrid-height coordinate data via interpolation (or where necessary, extrapolation).

All product files conform to the following naming convention:

IDYnnnnn.version.fields.levels.base-time.forecast-hour.grid-coords.ext

Sample NWP data

Links are provided below to documentation for ACCESS NWP products along with sample data files. Blank entries in the tables below indicate a product that is not available.

Future releases

Updated sample data will be made available via this portal as the ACCESS NWP data content and/or format evolves.

Answers to frequently asked questions about ACCESS NWP data

• Accumulated fields (including precipitation) are continuously accumulated from the start of the assimilation cycle. As such this field can be non-zero at the nominal analysis (base) time.
• Some spurious artefacts exist near the domain edges of ACCESS-R, ACCESS-C and ACCESS-TC models. Care should be taken when using data points from the outer 10 grid-points of these models. This is the region that the parent model is directly influencing, acting as an inflow and outflow for information. This region generates divergence, and enhanced precipitation in particular can be evident near this boundary region.
• Minor anomalies appear to be present in certain fields, including convective cloud base and cloud-top pressures as well as sensible heat fluxes which can appear excessive over small isolated regions at high latitudes).
• Fog, visibility & probability of visibility fields are experimental and have not been tuned for Australian conditions. They are included for evaluation purposes only.

Getting help and providing feedback

If you have a query about any information presented here or require further information or assistance about ACCESS NWP products please contact the Bureau's Real-time Data Services Section.