IDY25200: 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 of Meteorology's National Meteorological & Oceanographic Centre (NMOC). This document describes the content of the ACCESS-A (version APS0) IDY25200.all-flds.slv.YYYYMMDDHH.HHH.surface series of products.

An overview of the scientific and technical details of the ACCESS models can be found in NMOC's Operations Bulletin 83 http://www.bom.gov.au/nwp/doc/bulletins/apob83.pdf

If you require further information or assistance about ACCESS NWP products contact the Bureau's Registered User Services section.

Model summary

ACCESS-A covers the Australian domain, has a resolution of about 12 km and is run four times per day (00Z, 06Z, 12Z & 18Z basetimes) out to a forecast hour of +48. This model is nested in the ACCESS-R 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:

IDY25200.all-flds.slv.YYYYMMDDHH.HHH.surface.grb or IDY25200.all-flds.slv.YYYYMMDDHH.HHH.surface.nc

where

YYYYMMDDHHBase-date of model run in UTC time. YYYY = year, MM = month, DD = day, HH = hour
HHHForecast hour. A FHR of 000 is the analysis time-step.

Horizontal grid geometries

Resolution
[Lon x Lat]
Domain limits
[W to E, N to S (Lon x Lat grid points)]
GRIB parameters
[code.table]
0.110 by 0.110 95.000 to 169.690, 4.730 to -55.000 (680 x 544) 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 48 by 1

Parameters

Single-level fields

Par NetCDF var Steps Units Description
049.128 wndgust10m All m s-1 10m wind gust
165.128 u10 All m s-1 10m wind u component
166.128 v10 All m s-1 10m wind v component
057.228 accum_evap All kg m-2 Accumulated evaporation
058.228 accum_evap_sea All kg m-2 Accumulated evaporation over open sea
061.228 accum_prcp All kg m-2 Accumulated precipitation
143.228 accum_conv_prcp All kg m-2 Accumulative convective precipitation
239.228 accum_conv_snow All kg m-2 Accumulative convective snowfall
142.228 accum_ls_prcp All kg m-2 Accumulative large scale precipitation
240.228 accum_ls_snow All kg m-2 Accumulative large scale snowfall
213.228 av_lwsfcdown All W m-2 Average downwards longwave radiation at the surface
214.228 av_swsfcdown All W m-2 Average downwards shortwave radiation at the surface
216.228 av_swirrtop All W m-2 Average incoming shortwave radiation flux
202.228 av_mslp All Pa Average mean sea level pressure
234.228 av10v All m s-1 Average meridional wind at 10m
212.228 av_netlwsfc All W m-2 Average net longwave radiation at surface
211.228 av_netswsfc All W m-2 Average net shortwave radiation at surface
215.228 av_olr All W m-2 Average outgoing longwave radiation
200.228 av_temp_scrn All K Average screen level air temperature
253.228 av_qsair_scrn All kg kg-1 Average screen level specific humidity
221.228 av_lat_hflx All W m-2 Average surface latent heat flux
225.228 av_vwnd_strs All N m-2 Average surface meridional wind stress
222.228 av_sens_hflx All W m-2 Average surface sensible heat flux
047.228 av_sfc_sw_dif All W m-2 Average surface shortwave diffuse radiation flux
115.228 av_sfc_sw_dir All W m-2 Average surface shortwave direct radiation flux
224.228 av_uwnd_strs All N m-2 Average surface zonal wind stress
217.228 av_ttl_cld 3... 0-1 Average total cloud coverage
233.228 av10u All m s-1 Average zonal wind at 10m
087.128 canopy_wtr_cont All kg m-2 Canopy water content
089.128 conv_cldbse_pres 3... Pa Convective cloud-base pressure
090.128 conv_cldtop_pres 3... Pa Convective cloud-top pressure
210.229 fog_fraction All 0-1 Fog fraction
126.228 fric_vel All m s-1 Friction velocity
188.128 hi_cld All 0-1 High cloud cover
020.229 visibility All m Horizontal visibility
172.228 lnd_mask All 0/1 Land mask
186.128 low_cld All 0-1 Low cloud cover
151.128 mslp All Pa Mean sea level pressure
034.231 v50r All m s-1 Meridional wind at the 50m rho level
187.128 mid_cld All 0-1 Middle cloud cover
159.128 abl_ht All m Planetary boundary layer height
211.229 vis_prob All 0-1 Probability of horizontal visibility < 5km
109.128 z0 All m Roughness length
168.128 dewpt_scrn All K Screen level dewpoint temperature
201.128 tmax_scrn All K Screen level max temperature
202.128 tmin_scrn All K Screen level min temparature
081.128 qsair_scrn All kg kg-1 Screen level specific humidity
167.128 temp_scrn All K Screen level temperature
086.128 soil_mois_cont All kg m-2 Soil moisture available for transpiration
140.128 soil_mois All kg m-2 Soil moisture content layer 1
171.128 soil_mois All kg m-2 Soil moisture content layer 2
184.128 soil_mois All kg m-2 Soil moisture content layer 3
237.128 soil_mois All kg m-2 Soil moisture content layer 4
139.128 soil_temp All K Soil temperature layer 1
170.128 soil_temp All K Soil temperature layer 2
183.128 soil_temp All K Soil temperature layer 3
236.128 soil_temp All K Soil temperature layer 4
147.128 lat_hflx All W m-2 Surface latent heat flux
181.128 vwnd_strs All N m-2 Surface meridional wind stress
134.128 sfc_pres All Pa Surface pressure
146.128 sens_hflx All W m-2 Surface sensible heat flux
125.128 sfc_temp All K Surface temperature
180.128 uwnd_strs All N m-2 Surface zonal wind stress
156.228 topog All m Topography height
164.128 ttl_cld All 0-1 Total cloud cover
033.231 u50r All m s-1 Zonal wind at the 50m rho level

Explanation of steps column terms

AllParameter available at all time-steps
fhr...Parameter available from fhr onward

Appendix A - Notes on specific NWP file-formats

GRIB-1

ACCESS data in GRIB-1 format is defined relative to the Bureau's local GRIB tables. A copy of these tables in plain-text format is available for download from the ACCESS NWP web data interface.

Local extensions are also present in the GRIB-1 message headers. The following tables summarise these.

Section 1 octet Value Remarks
29-30 Stash ID 16-bit UM STASH ID.
31 4V offset Number of hours from start of 4V assimilation window to nominal analysis time.
19 P1 period of time Be aware that currently this is sometimes being set incorrectly for averaged, accumulated and max/min quantities (at certain timesteps only).
APS0 Model name GeneratingProcessIdentifier (ID of model)
ACCESS-G 1
ACCESS-T 10
ACCESS-R 20
ACCESS-A 30
ACCESS-VT 50
ACCESS-SY 54
ACCESS-BN 58
ACCESS-AD 62
ACCESS-PH 66
ACCESS-TC 80
ACCESS-O3 90

NetCDF

  • ACCESS NetCDF files aim to be broadly compliant with CF 1.4 conventions (http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html)
  • NetCDF data is of the "classic format" variant (compatible with the unidata NetCDF library version 3.6.x+)
  • Please ignore the accum_value metadata value. This parameter is not always set correctly for non-instantaneous fields.
  • Longitudes in the NetCDF files lie in the range [0.0 degrees, 360.0 degrees]. The NetCDF files somewhat misleadingly describe the valid range attribute for this dimension as -180 to +360.

Appendix B - Extended Field Descriptions

Extended description of single-level fields

Par NetCDF var Detailed description
049.128 wndgust10m Maximum gust windspeed at 10m above-ground-level. [m s-1]
165.128 u10 Zonal (U) component of the wind velocity at 10m above-ground-level. [m s-1]
166.128 v10 Meridional (V) component of the wind velocity at 10m above-ground-level. [m s-1]
057.228 accum_evap Evaporation from land soil surface. [kg m-2]
058.228 accum_evap_sea Evaporation from the open sea. It is weighted by the total sea (i.e. open sea and sea-ice) fraction. [kg m-2]
061.228 accum_prcp Accumulated total precipitation amount at the surface. This is the sum of the large scale rainfall, convective rainfall and snowfall at the surface. [kg m-2]
143.228 accum_conv_prcp Accumulated total convective rainfall amount at the surface. [kg m-2]
239.228 accum_conv_snow Accumulated total snow amount that falls to the surface. [kg m-2]
142.228 accum_ls_prcp Accumulated total large-scale rain amount at the surface. It does not include a convective contribution. [kg m-2]
240.228 accum_ls_snow Accumulated total large-scale snow amount that falls to the surface. It does not include a convective contribution. [kg m-2]
213.228 av_lwsfcdown Time-averaged downward flux of longwave radiation at the ground or ocean surface. [W m-2]
214.228 av_swsfcdown Time-averaged downward flux of shortwave radiation at the ground or ocean surface. [W m-2]
216.228 av_swirrtop Time-averaged incoming flux of shortwave radiation from the sun. [W m-2]
202.228 av_mslp Time-averaged atmospheric pressure at mean sea level. [Pa]
234.228 av10v Time-averaged meridional (V) component of the wind velocity at 10m above-ground-level. [m s-1]
212.228 av_netlwsfc Time-averaged net downward (total downward minus upward) radiative longwave flux at the surface (ground or ocean). [W m-2]
211.228 av_netswsfc Time-averaged net downward (total downward minus upward) radiative shortwave flux at the surface (ground or ocean). [W m-2]
215.228 av_olr Time-averaged longwave radiation flux leaving the top of the atmosphere. [W m-2]
200.228 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]
253.228 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]
221.228 av_lat_hflx Time-averaged latent heat flux at the surface (upward outgoing radiation values are positive). [W m-2]
225.228 av_vwnd_strs Time-averaged north-south (meridional) component of the surface stress. [N m-2]
222.228 av_sens_hflx Time-averaged sensible heat flux at the surface (upward outgoing radiation values are positive). [W m-2]
047.228 av_sfc_sw_dif Time-averaged downward diffuse shortwave radiation flux at the surface. [W m-2]
115.228 av_sfc_sw_dir Time-averaged downward direct shortwave radiation flux at the surface. [W m-2]
224.228 av_uwnd_strs Time-averaged east-west (zonal) component of the surface stress. [N m-2]
217.228 av_ttl_cld Time-averaged total cloud coverage calculated with a maximum-random overlap assumption. [0-1]
233.228 av10u Time-averaged zonal (U) component of the wind velocity at 10m above- ground-level. [m s-1]
087.128 canopy_wtr_cont Quantity of water held in the canopy. [kg m-2]
089.128 conv_cldbse_pres Atmospheric pressure at the convective cloud base. [Pa]
090.128 conv_cldtop_pres Atmospheric pressure at the convective cloud top. [Pa]
210.229 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. [0-1]
126.228 fric_vel Friction velocity (a scalar measure of the magnitude of the surface stress). [m s-1]
188.128 hi_cld High cloud cover, calculated under maximum overlap assumption between ICAO 500hPa and 150hPa levels (5574m and 13608m above mean sea level). [0-1]
020.229 visibility Estimated horizontal visibility at approximately 1.5m above-ground- level. Calculated from 1.5m T, q, qcl, qcf using droplet growth equations and assuming standard values for aerosol concentration, density, dry radius, etc. 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. [m]
172.228 lnd_mask Land mask (takes the value 1 if any land is in the grid box, otherwise 0). [0/1]
186.128 low_cld Low cloud cover, calculated under maximum overlap assumption between ICAO 1000hPa and 800Pa levels (111m and 1949m above mean sea level). [0-1]
151.128 mslp Atmospheric pressure at mean sea level. [Pa]
034.231 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]
187.128 mid_cld Middle cloud cover, calculated under maximum overlap assumption between ICAO 800hPa and 500Pa levels (1949m and 5574m above mean sea level). [0-1]
159.128 abl_ht Height above ground level of the top of the planetary boundary layer (i.e. boundary layer depth). [m]
211.229 vis_prob Probability of horizontal visibility at approximately 1.5m above-ground- level being less than 5 km. 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. [0-1]
109.128 z0 Roughness length. [m]
168.128 dewpt_scrn Dewpoint temperature at 1.5m above ground level (screen level). [K]
201.128 tmax_scrn Maximum atmospheric air temperature at 1.5m above ground-level (screen level). [K]
202.128 tmin_scrn Minimum atmospheric air temperature at 1.5m above ground-level (screen level). [K]
081.128 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]
167.128 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]
086.128 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]
140.128 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 1 (surface to 0.1m depth). [kg m-2]
171.128 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 2 (0.10m to 0.25m depth). [kg m-2]
184.128 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 3 (0.25m to 0.65m depth). [kg m-2]
237.128 soil_mois Total (frozen and unfrozen) soil moisture content in soil layer 4 (0.65m to 2.00m depth). [kg m-2]
139.128 soil_temp Soil/land-ice temperature in soil layer 1 (surface to 0.1m depth). [K]
170.128 soil_temp Soil/land-ice temperature in soil layer 1 (0.10m to 0.25m depth). [K]
183.128 soil_temp Soil/land-ice temperature in soil layer 1 (0.25m to 0.65m depth). [K]
236.128 soil_temp Soil/land-ice temperature in soil layer 1 (0.65m to 2.00m depth). [K]
147.128 lat_hflx Latent heat flux at the surface (upward outgoing radiation values are positive). [W m-2]
181.128 vwnd_strs The north-south (meridional) component of the surface stress. [N m-2]
134.128 sfc_pres Atmospheric pressure at the surface. [Pa]
146.128 sens_hflx Surface sensible heat flux (upward outgoing radiation values are positive) [W m-2]
125.128 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]
180.128 uwnd_strs The east-west (zonal) component of the surface stress. [N m-2]
156.228 topog Height of topography (above the geoid). [m]
164.128 ttl_cld Total cloud coverage calculated with a maximum-random overlap assumption. [0-1]
033.231 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.
  • 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.