ACCESS-PH: Hybrid-height (all-lvls) "pop-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 PERTH (version APS3) IDY25403.APS3.pop-flds.all-lvls.YYYYMMDDHH.HHH.model 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 PERTH covers the Perth/Southwest WA 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:
IDY25403.APS3.pop-flds.all-lvls.YYYYMMDDHH.HHH.model.grb2
where
YYYYMMDDHH | Base-date of model run in UTC time. YYYY = year, MM = month, DD = day, HH = hour |
---|---|
HHH | Forecast hour. A HHH of 000 is the analysis time-step. |
Horizontal grid geometries
Resolution
[Lon x Lat]
|
Domain limits
[W to E, S to N (Lon x Lat grid points)]
|
Parameters
[NC Vars]
|
---|---|---|
0.013 by 0.013 | 112.000 to 124.028, -37.000 to -26.970 (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.
Vertical levels
- Eta-level index values:
- 1 to 80 by 1
All fields lie on eta "theta" levels. Refer to Appendix B for more information.
Time steps
- Forecast hours of multi-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.
Multi-level fields
G2 d.c.n | NetCDF var | Steps | G2 Units | NC Units | Description |
---|---|---|---|---|---|
0.0.6 | dewpt | All | K | K | Dew point |
0.2.3 | merid_wnd | All | m s-1 | m s-1 | Meridional wind |
0.3.0 | pressure | All | Pa | Pa | Pressure (t/q or theta surface) |
0.0.0 | air_temp | All | K | K | Temperature |
0.2.9 | vertical_wnd | All | m s-1 | m s-1 | Vertical velocity |
0.2.2 | zonal_wnd | All | m s-1 | m s-1 | Zonal wind |
Explanation of steps column terms
All | Parameter available at all time-steps |
---|---|
All but steps | Parameter 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 multi-level fields
G2 d.c.n | NetCDF var | Detailed description |
---|---|---|
0.0.6 | 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] |
0.2.3 | merid_wnd | Meridional (V) component of the wind velocity. [m s-1] |
0.3.0 | pressure | Pressure on native model theta-eta levels. [Pa] |
0.0.0 | air_temp | Air temperature. [K] |
0.2.9 | vertical_wnd | Vertical (W) component of the wind velocity. Positive values indicate air moving upward. [m s-1] |
0.2.2 | zonal_wnd | Zonal (U) component of the wind velocity. [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. It is always safest to refer to the detailed description of a parameter.
Appendix B - Hybrid Height Levels
Level index | A [theta] | B [theta] | A [rho] | B [rho] |
---|---|---|---|---|
80 | 38500.00000000 | 0.00000000 | 37771.77250000 | 0.00000000 |
79 | 37044.54215000 | 0.00000000 | 36351.59990000 | 0.00000000 |
78 | 35658.65380000 | 0.00000000 | 34997.77820000 | 0.00000000 |
77 | 34336.90260000 | 0.00000000 | 33706.01465000 | 0.00000000 |
76 | 33075.12285000 | 0.00000000 | 32472.27060000 | 0.00000000 |
75 | 31869.41450000 | 0.00000000 | 31292.77305000 | 0.00000000 |
74 | 30716.13160000 | 0.00000000 | 30163.98770000 | 0.00000000 |
73 | 29611.84380000 | 0.00000000 | 29082.61510000 | 0.00000000 |
72 | 28553.38255000 | 0.00000000 | 28045.57525000 | 0.00000000 |
71 | 27537.77180000 | 0.00000000 | 27050.01145000 | 0.00000000 |
70 | 26562.24725000 | 0.00000000 | 26093.24025000 | 0.00000000 |
69 | 25624.23325000 | 0.00000000 | 25172.78610000 | 0.00000000 |
68 | 24721.33510000 | 0.00000000 | 24286.33130000 | 0.00000000 |
67 | 23851.32750000 | 0.00000000 | 23431.74680000 | 0.00000000 |
66 | 23012.16225000 | 0.00000000 | 22607.04600000 | 0.00000000 |
65 | 22201.92590000 | 0.00000000 | 21810.39245000 | 0.00000000 |
64 | 21418.86285000 | 0.00000000 | 21040.09600000 | 0.00000000 |
63 | 20661.33300000 | 0.00000000 | 20294.59355000 | 0.00000000 |
62 | 19927.85410000 | 0.00000000 | 19572.44520000 | 0.00000000 |
61 | 19217.04015000 | 0.00000000 | 18872.32655000 | 0.00000000 |
60 | 18527.61680000 | 0.00000000 | 18193.02485000 | 0.00000000 |
59 | 17858.43290000 | 0.00033824 | 17533.42360000 | 0.00131448 |
58 | 17208.42200000 | 0.00292895 | 16892.51025000 | 0.00511000 |
57 | 16576.60235000 | 0.00789405 | 16269.34925000 | 0.01118031 |
56 | 15962.10000000 | 0.01503696 | 15663.09745000 | 0.01933777 |
55 | 15364.09490000 | 0.02417879 | 15072.98100000 | 0.02941112 |
54 | 14781.86325000 | 0.03515562 | 14498.29920000 | 0.04124341 |
53 | 14214.73130000 | 0.04781717 | 13938.42065000 | 0.05469007 |
52 | 13662.11000000 | 0.06202431 | 13392.77555000 | 0.06961739 |
51 | 13123.44495000 | 0.07764869 | 12860.84800000 | 0.08590121 |
50 | 12598.25490000 | 0.09457027 | 12342.17215000 | 0.10342571 |
49 | 12086.09325000 | 0.11267726 | 11836.33605000 | 0.12208212 |
48 | 11586.57885000 | 0.13186391 | 11342.96625000 | 0.14176817 |
47 | 11099.35365000 | 0.15203105 | 10861.73165000 | 0.16238703 |
46 | 10624.10580000 | 0.17308439 | 10392.33580000 | 0.18384681 |
45 | 10160.56195000 | 0.19493402 | 9934.52075000 | 0.20605965 |
44 | 9708.48340000 | 0.21749382 | 9488.06320000 | 0.22894117 |
43 | 9267.64300000 | 0.24068210 | 9052.75140000 | 0.25241116 |
42 | 8837.85980000 | 0.26441926 | 8628.41210000 | 0.27639167 |
41 | 8418.96440000 | 0.28862917 | 8214.89130000 | 0.30080760 |
40 | 8010.82205000 | 0.31323744 | 7812.05810000 | 0.32558604 |
39 | 7613.29800000 | 0.33817312 | 7419.79700000 | 0.35065648 |
38 | 7226.29215000 | 0.36336634 | 7038.00405000 | 0.37595074 |
37 | 6849.71210000 | 0.38874963 | 6666.59840000 | 0.40140201 |
36 | 6483.48085000 | 0.41425727 | 6305.50305000 | 0.42694588 |
35 | 6127.52910000 | 0.43982561 | 5954.66410000 | 0.45251885 |
34 | 5781.80295000 | 0.46539237 | 5614.02765000 | 0.47805979 |
33 | 5446.25620000 | 0.49089700 | 5283.55135000 | 0.50350900 |
32 | 5120.85035000 | 0.51628065 | 4963.20055000 | 0.52880838 |
31 | 4805.55460000 | 0.54148597 | 4652.94830000 | 0.55390134 |
30 | 4500.34200000 | 0.56645742 | 4352.76765000 | 0.57873333 |
29 | 4205.19330000 | 0.59114084 | 4062.64320000 | 0.60325087 |
28 | 3920.09310000 | 0.61548370 | 3782.56109000 | 0.62740228 |
27 | 3645.02831000 | 0.63943522 | 3512.50707500 | 0.65113782 |
26 | 3379.98584000 | 0.66294654 | 3252.47345500 | 0.67440911 |
25 | 3124.96184000 | 0.68596985 | 3002.45522500 | 0.69716936 |
24 | 2879.94899500 | 0.70845952 | 2762.44661000 | 0.71937373 |
23 | 2644.94384000 | 0.73037141 | 2532.44376000 | 0.74097903 |
22 | 2419.94329500 | 0.75166317 | 2312.44436500 | 0.76194377 |
21 | 2204.94543500 | 0.77229419 | 2102.44727000 | 0.78222815 |
20 | 1999.94910500 | 0.79222559 | 1902.45132000 | 0.80179422 |
19 | 1804.95353500 | 0.81142029 | 1712.45613000 | 0.82060576 |
18 | 1619.95834000 | 0.82984297 | 1532.46054500 | 0.83862844 |
17 | 1444.96236500 | 0.84746022 | 1362.46456500 | 0.85582964 |
16 | 1279.96676500 | 0.86424018 | 1202.46857500 | 0.87217849 |
15 | 1124.97077000 | 0.88015304 | 1052.47257500 | 0.88764599 |
14 | 979.97438000 | 0.89517070 | 912.47618000 | 0.90220500 |
13 | 844.97798000 | 0.90926683 | 782.47977500 | 0.91583009 |
12 | 719.98118500 | 0.92241700 | 662.48297500 | 0.92849775 |
11 | 604.98438000 | 0.93459852 | 552.48578000 | 0.94018622 |
10 | 499.98718000 | 0.94579057 | 452.48819000 | 0.95087555 |
9 | 404.98958500 | 0.95597413 | 362.49062850 | 0.96054759 |
8 | 319.99171050 | 0.96513196 | 282.49267200 | 0.96918605 |
7 | 244.99363350 | 0.97324864 | 212.49447450 | 0.97677643 |
6 | 179.99531550 | 0.98031060 | 152.49603600 | 0.98330603 |
5 | 124.99675650 | 0.98630603 | 102.49735650 | 0.98876398 |
4 | 79.99791800 | 0.99122498 | 62.49839750 | 0.99314121 |
3 | 44.99883850 | 0.99505929 | 32.49915900 | 0.99643049 |
2 | 19.99948335 | 0.99780262 | 12.49967565 | 0.99862635 |
1 | 4.99987180 | 0.99945043 | 2.49993513 | 0.99972520 |
- Notes:
[theta] and [rho] denote the level types on which the parameters A and B are valid.
A values represent the height of the hybrid levels above the geoid assuming zero topography.
B values represent the fraction of the topographic height included in the hybrid levels.
The height of a hybrid-height level (m) can be calculated via:
z(k, i, j) = A(k) + B(k)*topo(i, j) where k denotes the level index, z(k, i, j) is the height above the geoid at grid-point (i, j, k), topo(i, j) is the height of the surface above the geoid at (i, j) and A(k) & B(k) are the values of A and B at level k.