ACCESS-SY: single-level "all-flds" 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 SYDNEY (version APS3) IDY25401.APS3.all-flds.slv.YYYYMMDDHH.HHH.surface and IDY25421.APS3.all-flds.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 SYDNEY covers the Sydney 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:

IDY25401.APS3.all-flds.slv.YYYYMMDDHH.HHH.surface.grb2 or

IDY25421.APS3.all-flds.slv.YYYYMMDDHH.HHH.surface.grb2

where

YYYYMMDDHHBase-date of model run in UTC time. YYYY = year, MM = month, DD = day, HH = hour
HHHForecast 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]
IDY25401
 0.014 by 0.013 144.000 to 156.029, -38.000 to -27.970 (892 x 744) All
IDY25421
 0.014 by 0.013 144.000 to 156.029, -38.000 to -27.970 (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
0.2.2 u10 All m s-1 m s-1 10m wind u component
0.2.3 v10 All m s-1 m s-1 10m wind v component
0.1.6 accum_evap All kg m-2 kg m-2 Accumulated evaporation from land soil surface
0.1.8 accum_prcp All kg m-2 kg m-2 Accumulated precipitation
0.1.49 accum_rain All kg m-2 kg m-2 Accumulated rainfall
0.1.50 accum_snow All kg m-2 kg m-2 Accumulated snowfall
0.5.3 av_lwsfcdown 1... W m-2 W m-2 Average downwards longwave radiation at the surface
0.4.7 av_swsfcdown 1... W m-2 W m-2 Average downwards shortwave radiation at the surface
0.4.7 av_swirrtop 1... W m-2 W m-2 Average incoming shortwave radiation flux
0.3.1 av_mslp 1... Pa Pa Average mean sea level pressure
0.2.3 av10v 1... m s-1 m s-1 Average meridional wind at 10m
0.5.5 av_netlwsfc 1... W m-2 W m-2 Average net longwave radiation at surface
0.4.9 av_netswsfc 1... W m-2 W m-2 Average net shortwave radiation at surface
0.5.4 av_olr 1... W m-2 W m-2 Average outgoing longwave radiation
0.1.206 av_evap_sea 1... kg m-2 s-1 kg m-2 s-1 Average rate of evaporation over open sea
0.0.0 av_temp_scrn 1... K K Average screen level air temperature
0.1.0 av_qsair_scrn 1... kg kg-1 kg kg-1 Average screen level specific humidity
0.0.10 av_lat_hflx 1... W m-2 W m-2 Average surface latent heat flux
0.2.18 av_vwnd_strs 1... N m-2 N m-2 Average surface meridional wind stress
0.0.11 av_sens_hflx 1... W m-2 W m-2 Average surface sensible heat flux
0.4.202 av_sfc_sw_dif 1... W m-2 W m-2 Average surface shortwave diffuse radiation flux
0.4.203 av_sfc_sw_dir 1... W m-2 W m-2 Average surface shortwave direct radiation flux
0.2.17 av_uwnd_strs 1... N m-2 N m-2 Average surface zonal wind stress
0.6.1 av_ttl_cld 1... % 1 Average total cloud coverage
0.1.207 av_sfc_mois_flx 1... kg m-2 s-1 kg m-2 s-1 Average total surface moisture flux
0.2.2 av10u 1... m s-1 m s-1 Average zonal wind at 10m
2.0.13 canopy_wtr_cont All kg m-2 kg m-2 Canopy water content
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)
2.0.0 lnd_mask All 1 1 Land mask
0.6.3 low_cld All % 1 Low cloud cover
0.16.5 max_maxcol_refl 1... dB dBZ Maximum derived composite radar reflectivity
0.7.15 max_updraft_helicity 1... m2 s-2 m2 s-2 Maximum updraft helicity
0.16.4 max_radar_refl_1km 1... dB dBZ Maxmium derived radar reflectivity at 1km agl
0.3.1 mslp All Pa Pa Mean sea level pressure
0.2.3 v50r All m s-1 m s-1 Meridional wind at the 50m rho level
0.6.4 mid_cld All % 1 Middle cloud cover
0.7.15 min_updraft_helicity 1... m2 s-2 m2 s-2 Minimum updraft helicity
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
0.19.0 prob_vis_5km_ppt All 1 1 Probability of horizontal visibility less than 5 km (incl precip)
0.0.6 dewpt_scrn All K K Screen level dewpoint temperature
0.0.4 tmax_scrn 1... K K Screen level max temperature
0.0.5 tmin_scrn 1... K K Screen level min temperature
0.1.1 rh2m All % % Screen level relative humidity w.r.t. water
0.1.0 qsair_scrn All kg kg-1 kg kg-1 Screen level specific humidity
0.0.0 temp_scrn All K K Screen level temperature
2.0.206 soil_mois_cont All kg m-2 kg m-2 Soil moisture available for transpiration
2.0.3 soil_mois All kg m-2 kg m-2 Soil moisture content in a layer
2.0.3 soil_mois All kg m-2 kg m-2 Soil moisture content layer 2
2.0.3 soil_mois All kg m-2 kg m-2 Soil moisture content layer 3
2.0.3 soil_mois All kg m-2 kg m-2 Soil moisture content layer 4
2.3.18 soil_temp All K K Soil temperature in a layer
2.3.18 soil_temp All K K Soil temperature layer 2
2.3.18 soil_temp All K K Soil temperature layer 3
2.3.18 soil_temp All K K Soil temperature layer 4
0.0.10 lat_hflx All W m-2 W m-2 Surface latent heat flux
0.2.18 vwnd_strs All N m-2 N m-2 Surface meridional wind stress
0.3.0 sfc_pres All Pa Pa Surface pressure
2.0.1 sfc_rough_len All m m Surface roughness length for momentum
0.0.11 sens_hflx All W m-2 W m-2 Surface sensible heat flux
0.0.0 sfc_temp All K K Surface temperature
0.2.17 uwnd_strs All N m-2 N m-2 Surface zonal wind stress
0.3.5 topog All gpm gpm Topography height above msl
0.6.1 ttl_cld All % 1 Total cloud cover
0.2.2 u50r All m s-1 m s-1 Zonal wind at the 50m rho level

Explanation of steps column terms

AllParameter available at all time-steps
All but stepsParameter 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]
0.2.2 u10 Zonal (U) component of the wind velocity at 10m above ground level. [m s-1]
0.2.3 v10 Meridional (V) component of the wind velocity at 10m above ground level. [m s-1]
0.1.6 accum_evap Accumulated evaporation from land soil surface. [kg m-2]
0.1.8 accum_prcp Accumulated total precipitation amount at the surface. This is the sum of rainfall and snowfall at the surface. [kg m-2]
0.1.49 accum_rain Accumulated total rainfall amount at the surface. [kg m-2]
0.1.50 accum_snow Accumulated total snow amount that falls to the surface. [kg m-2]
0.5.3 av_lwsfcdown Time-averaged downward flux of longwave radiation at the ground or ocean surface. [W m-2]
0.4.7 av_swsfcdown Time-averaged downward flux of shortwave radiation at the ground or ocean surface. [W m-2]
0.4.7 av_swirrtop Time-averaged incoming flux of shortwave radiation from the sun. [W m-2]
0.3.1 av_mslp Time-averaged atmospheric pressure at mean sea level. [Pa]
0.2.3 av10v Time-averaged meridional (V) component of the wind velocity at 10m above ground level. [m s-1]
0.5.5 av_netlwsfc Time-averaged net downward (total downward minus upward) radiative longwave flux at the surface (ground or ocean). [W m-2]
0.4.9 av_netswsfc Time-averaged net downward (total downward minus upward) radiative shortwave flux at the surface (ground or ocean). [W m-2]
0.5.4 av_olr Time-averaged longwave radiation flux leaving the top of the atmosphere. [W m-2]
0.1.206 av_evap_sea Time-averaged rate of evaporation over open sea. [kg m-2 s-1]
0.0.0 av_temp_scrn Time-averaged atmospheric temperature at 1.5m above ground level (screen level). Calculated by integrating the similarity equations from the surface to 1.5m. [K]
0.1.0 av_qsair_scrn Time-averaged atmospheric specific humidity at 1.5m above ground level (screen level). Calculated by integrating the similarity equations from the surface to 1.5m (surface value taken as saturated specific humidity at the surface temperature). [kg kg-1]
0.0.10 av_lat_hflx Time-averaged latent heat flux at the surface (upward outgoing radiation values are positive). [W m-2]
0.2.18 av_vwnd_strs Time-averaged north-south (meridional) component of the surface stress. [N m-2]
0.0.11 av_sens_hflx Time-averaged sensible heat flux at the surface. This represents the time-averaged exchange of heat between the surface and the air by motion of air; also called “turbulent” heat flux. [W m-2]
0.4.202 av_sfc_sw_dif Time-averaged downward diffuse shortwave radiation flux at the surface. [W m-2]
0.4.203 av_sfc_sw_dir Time-averaged downward direct shortwave radiation flux at the surface. [W m-2]
0.2.17 av_uwnd_strs Time-averaged east-west (zonal) component of the surface stress. [N m-2]
0.6.1 av_ttl_cld Time-averaged total cloud coverage calculated with a maximum-random overlap assumption. [1]
0.2.2 av10u Time-averaged zonal (U) component of the wind velocity at 10m above ground level. [m s-1]
2.0.13 canopy_wtr_cont Quantity of water held in the canopy. [kg m-2]
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]
2.0.0 lnd_mask Land mask (takes the value 1 or -1 if any land is in the grid box, otherwise 0). [1]
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]
0.16.5 max_maxcol_refl Maximum (over a time window) composite derived radar reflectivity denoting the maximum forecast in the column from the surface to the top of the model. This includes contributions from rain, snow, graupel and liquid cloud. [dBZ]
0.7.15 max_updraft_helicity Maximum (over a time window) updraft helicity over a 2km to 5km above ground layer. Updraft helicity here is defined as the integral of vertical velocity multiplied by the vertical component of relative vorticity with height for all upward (postive) vertical velocities (i.e. helicity contributions from downdrafts are ignored). Note: values are model-resolution dependent. Rising anti-cyclonic rotation will have positive values in the Southern Hemisphere. [m2 s-2]
0.16.4 max_radar_refl_1km Maximum (over a time window) derived radar reflectivity at a constant height of 1km above ground level. This includes contributions from rain, snow, graupel and liquid cloud. [dBZ]
0.3.1 mslp Atmospheric pressure at mean sea level. [Pa]
0.2.3 v50r Meridional (V) component of the "50m" rho-level winds (the hybrid- height level with an eta value of 0.0007947). This is the same field as level index 2 rho-level V but has been made available as a single-level "destaggered" field for convenience. [m s-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]
0.7.15 min_updraft_helicity Minimum (over a time window) updraft helicity over a 2km to 5km above ground layer. Updraft helicity here is defined as the integral of vertical velocity multiplied by the vertical component of relative vorticity with height for all upward (postive) vertical velocities (i.e. helicity contributions from downdrafts are ignored). Note: values are model-resolution dependent. Rising cyclonic rotation will have negative values in the Southern Hemisphere. [m2 s-2]
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]
0.19.0 prob_vis_5km_ppt Probability of horizontal visibility at approximately 1.5m above ground level being less than 5 km with precipitation taken into account. 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]
0.0.6 dewpt_scrn Dewpoint temperature at 1.5m above ground level (screen level). [K]
0.0.4 tmax_scrn Maximum (over a time window) atmospheric air temperature at 1.5m above ground level (screen level). [K]
0.0.5 tmin_scrn Minimum (over a time window) atmospheric air temperature at 1.5m above ground level (screen level). [K]
0.1.1 rh2m Relative humidity at 1.5m above ground level (screen level). Calculated as 100*water_vapour_pressure/saturation_partial_pressure_of_water_vapour where the the saturation partial pressure of water vapour represents the saturation vapour pressure over liquid water for temperatures above the triple point, over ice for temperatures 20 degrees below the triple point, and a linear combination of the two for temperatures in-between. [%]
0.1.0 qsair_scrn Atmospheric specific humidity at 1.5m above ground level (screen level). Calculated by integrating the similarity equations from the surface to 1.5m (surface value taken as saturated specific humidity at the surface temperature). [kg kg-1]
0.0.0 temp_scrn Atmospheric temperature at 1.5m above ground level (screen level). Calculated by integrating the similarity equations from the surface to 1.5m. [K]
2.0.206 soil_mois_cont A measure of soil moisture in the root-zone available for transpiration by plants. The rootzone extends to a depth of about 1m below the soil surface. This field is defined to be the difference between the actual unfrozen soil moisture and the wilting point to the rootzone depth. Note: if the actual soil moisture in a layer falls below the wilting point then this field can be negative, which implies water needs to added for transpiration to take place. [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]
2.0.3 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 2 (0.10m to 0.35m depth). [kg m-2]
2.0.3 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 3 (0.35m to 1.00m depth). [kg m-2]
2.0.3 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 4 (1.00m to 3.00m depth). [kg m-2]
2.3.18 soil_temp Mean soil/land-ice temperature within soil layer 1 (surface to 0.1m depth). [K]
2.3.18 soil_temp Mean soil/land-ice temperature within soil layer 1 (0.10m to 0.35m depth). [K]
2.3.18 soil_temp Mean soil/land-ice temperature within soil layer 1 (0.35m to 1.00m depth). [K]
2.3.18 soil_temp Mean soil/land-ice temperature within soil layer 1 (1.00m to 3.00m depth). [K]
0.0.10 lat_hflx Latent heat flux at the surface (upward outgoing radiation values are positive). [W m-2]
0.2.18 vwnd_strs The north-south (meridional) component of the surface stress. [N m-2]
0.3.0 sfc_pres Atmospheric pressure at the surface. [Pa]
2.0.1 sfc_rough_len Surface roughness length for momentum in air. A constant of integration in the logarithmic wind profile. In this diagnostic, the effective roughness of subgrid model orography has been neglected. [m]
0.0.11 sens_hflx Surface sensible heat flux. This represents the exchange of heat between the surface and the air by motion of air; also called “turbulent” heat flux. [W m-2]
0.0.0 sfc_temp Temperature of the land or sea/sea-ice surface. On land points this is the surface "skin" temperature. On ice-free sea points it is the temperature of the sea surface, and on sea points with ice it is a gridbox mean given by: [(ice fraction)*(temperature of top ice layer computed by the atmosphere surface/boundary layer scheme)] + [(1 - ice fraction)*(freezing point of sea water)]. [K]
0.2.17 uwnd_strs The east-west (zonal) component of the surface stress. [N m-2]
0.3.5 topog Height of topography (above the geoid). [gpm]
0.6.1 ttl_cld Total cloud coverage calculated with a maximum-random overlap assumption. [1]
0.2.2 u50r Zonal (U) component of the "50m" rho-level winds (the hybrid-height level with an eta value of 0.0007947). This is the same field as level index 2 rho-level U but has been made available as a single-level "destaggered" field for convenience. [m s-1]

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. In particular the 'soil_mois_cont' variable name could be misleading. 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).
  • Maximum and minimum screen-level temperatures represent a maximum/minimum value over the period from the last model output time-step to the field's nominal forecast-hour.
  • The geoid surface is at approximately mean sea level.