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-C SYDNEY (version APS0) IDY25401.pop-flds.500.YYYYMMDDHH.HHH.pressure 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.
ACCESS-C SYDNEY covers the Sydney domain, has a resolution of about 5 km and is run twice per day (00Z and 12Z basetimes) out to a forecast hour of +36. This model is nested in the ACCESS-R model and consists of only a forecast component.
All NWP files in this product series have names that conform to the following convention:
IDY25401.pop-flds.500.YYYYMMDDHH.HHH.pressure.grb or IDY25401.pop-flds.500.YYYYMMDDHH.HHH.pressure.nc
where
YYYYMMDDHH | Base-date of model run in UTC time. YYYY = year, MM = month, DD = day, HH = hour |
---|---|
HHH | Forecast hour. A FHR of 000 is the analysis time-step. |
Resolution
[Lon x Lat]
|
Domain limits
[W to E, N to S (Lon x Lat grid points)]
|
GRIB parameters
[code.table]
|
---|---|---|
0.050 by 0.050 | 147.000 to 154.950, -30.050 to -38.000 (160 x 160) | All |
Please note that
Par | NetCDF var | Steps | Units | Description |
---|---|---|---|---|
017.228 | dewpt | All | K | Dew point |
156.128 | geop_ht | All | m | Geopotential height |
132.128 | merid_wnd | All | m s-1 | Meridional wind |
130.128 | air_temp | All | K | Temperature |
134.228 | vertical_wnd | All | m s-1 | Vertical velocity |
131.128 | zonal_wnd | All | m s-1 | Zonal wind |
Explanation of steps column terms
All | Parameter available at all time-steps |
---|---|
fhr... | Parameter available from fhr onward |
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
Par | NetCDF var | Detailed description |
---|---|---|
017.228 | dewpt | Dewpoint temperature. Calculated by (iteratively) finding the temperature at which the partial pressure due to water vapour equals the saturated water vapour partial pressure where 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. [K] |
156.128 | geop_ht | Geopotential height of level (m above the geoid). [m] |
132.128 | merid_wnd | Meridional (V) component of the wind velocity. [m s-1] |
130.128 | air_temp | Air temperature. [K] |
134.228 | vertical_wnd | Vertical (W) component of the wind velocity. [m s-1] |
131.128 | zonal_wnd | Zonal (U) component of the wind velocity. [m s-1] |
Please note: