Aim of this page :
- a table with NCEP data: GRIB sample (only one message and one parameter), encoding explained (not only parameter we need to have all the significant descriptions including the geography)
- A table with what we aim to have from the partners. Description in words, GRIB2 coding (not only parameter also all other relevant coding details), possibly an example of grib for each parameter
- A common description of the grid we are going to ask the users. We said that this is going to be a global domain. I think we also need a bitmap.
After talking with Jean Bidlot we concluded that what we are asking our contributor for in GRIB2 language is :
| parameter | Discipline | Category | parameterNumber | Description | ||
|---|---|---|---|---|---|---|
| 1 | U-component of wind ( 10 m ) | 0 [ Meteorological products ] | 2 [ Momentum ] | 2 | ||
| 2 | V-component of wind ( 10 m ) | 0 [ Meteorological products ] | 2 [ Momentum ] | 3 | ||
| 3 | Significant height of combined wind waves and swell | 10 [ Oceanographic products ] | 0 [ Waves ] | 3 | ||
| 4 | Peak wave period | 10 [ Oceanographic products ] | 0 [ Waves ] | 34 | Mean wave period based on the second moment of the frequency spectrum | |
| 5 | Mean zero-crossing wave period | 10 [ Oceanographic products ] | 0 [ Waves ] | 28 | ||
| 6 | Direction of combined wind waves and swell | 10 [ Oceanographic products ] | 0 [ Waves ] | 14 | Mean wave direction |
NCEP GRIB2 summary
Parameters :
( 1 message <=> 1 parameter )
01 parameterNumber = 1 Wind speed (m s-1)
02 parameterNumber = 0 Wind direction [from which blowing] (deg true)
03 parameterNumber = 2 u-component of wind (m s-1)
04 parameterNumber = 3 v-component of wind (m s-1)
05 parameterNumber = 3 Significant height of combined wind waves and swell (m)
06 parameterNumber = 11 Primary wave mean period (s)
07 parameterNumber = 10 Primary wave direction (Degree true)
08 parameterNumber = 5 Significant height of wind waves (m)
09 parameterNumber = 8 Significant height of swell waves (m)
10 parameterNumber = 8 Significant height of swell waves (m)
11 parameterNumber = 6 Mean period of wind waves (s)
12 parameterNumber = 9 Mean period of swell waves (s)
13 parameterNumber = 9 Mean period of swell waves (s)
14 parameterNumber = 4 Direction of wind waves (Degree true)
15 parameterNumber = 7 Direction of swell waves (Degree true)
16 parameterNumber = 7 Direction of swell waves (Degree true)
Sections :
Sections 1, 3 and 6 ( bitmap ) are identical over all the messages.
Sections 0 differ on the values of "discipline". There are two values for "discipline" : 0 [ Meteorological products ] for messages 1,2,3,4; and 10 [ Oceanographic products ] for the other messages.
Section 2 is absent from all messages
Sections 4 differ on the values of "parameterCategory" and "parameterNumber". There are two vales for "parameterCategory" : 2 [ Momentum ] for messages 1,2,3,4; and 0 [ Waves ] for the other messages.
Sections 5 and 7 differs as expected since the data are different.
Dump of one of the messages
( Note that since the sections over all the messages are quite similar this dump summarizes the whole content of the file )
#============== MESSAGE 4 ( length=179708 ) ==============
1-4 identifier = GRIB
5-6 reserved = 0
7 discipline = 0 [Meteorological products (grib2/tables/2/0.0.table) ]
8 editionNumber = 2
9-16 totalLength = 179708
====================== SECTION_1 ( length=21, padding=0 ) ======================
1-4 section1Length = 21
5 numberOfSection = 1
6-7 centre = 7 [US National Weather Service - NCEP (WMC) (grib2/centre.table) ]
8-9 subCentre = 0
10 tablesVersion = 2 [Version implemented on 4 November 2003 (grib2/tables/1.0.table) ]
11 localTablesVersion = 1 [Unknown code table entry (grib2/tables/2/1.1.table) ]
12 significanceOfReferenceTime = 1 [Start of forecast (grib2/tables/2/1.2.table) ]
13-14 year = 2017
15 month = 1
16 day = 30
17 hour = 0
18 minute = 0
19 second = 0
20 productionStatusOfProcessedData = 0 [Operational products (grib2/tables/2/1.3.table) ]
21 typeOfProcessedData = 1 [Forecast products (grib2/tables/2/1.4.table) ]
====================== SECTION_3 ( length=72, padding=0 ) ======================
1-4 section3Length = 72
5 numberOfSection = 3
6 sourceOfGridDefinition = 0 [Specified in Code table 3.1 (grib2/tables/2/3.0.table) ]
7-10 numberOfDataPoints = 241920
11 numberOfOctectsForNumberOfPoints = 0
12 interpretationOfNumberOfPoints = 0 [There is no appended list (grib2/tables/2/3.11.table) ]
13-14 gridDefinitionTemplateNumber = 0 [Latitude/longitude. Also called equidistant cylindrical, or Plate Carree (grib2/tables/2/3.1.table) ]
15 shapeOfTheEarth = 6 [Earth assumed spherical with radius of 6,371,229.0 m (grib2/tables/2/3.2.table) ]
16 scaleFactorOfRadiusOfSphericalEarth = 0
17-20 scaledValueOfRadiusOfSphericalEarth = 0
21 scaleFactorOfEarthMajorAxis = 0
22-25 scaledValueOfEarthMajorAxis = 0
26 scaleFactorOfEarthMinorAxis = 0
27-30 scaledValueOfEarthMinorAxis = 0
31-34 Ni = 720
35-38 Nj = 336
39-42 basicAngleOfTheInitialProductionDomain = 0
43-46 subdivisionsOfBasicAngle = 0
47-50 latitudeOfFirstGridPoint = 90000000
51-54 longitudeOfFirstGridPoint = 0
55 resolutionAndComponentFlags = 48 [00110000]
56-59 latitudeOfLastGridPoint = -77500000
60-63 longitudeOfLastGridPoint = 359500000
64-67 iDirectionIncrement = 500000
68-71 jDirectionIncrement = 500000
72 scanningMode = 0 [00000000]
====================== SECTION_4 ( length=34, padding=0 ) ======================
1-4 section4Length = 34
5 numberOfSection = 4
6-7 NV = 0
8-9 productDefinitionTemplateNumber = 0 [Analysis or forecast at a horizontal level or in a horizontal layer at a point in time (grib2/tables/2/4.0.table) ]
10 parameterCategory = 2 [Momentum (grib2/tables/2/4.1.0.table) ]
11 parameterNumber = 3 [v-component of wind (m s-1) (grib2/tables/2/4.2.0.2.table) ]
12 typeOfGeneratingProcess = 2 [Forecast (grib2/tables/2/4.3.table) ]
13 backgroundProcess = 0
14 generatingProcessIdentifier = 11
15-16 hoursAfterDataCutoff = 0
17 minutesAfterDataCutoff = 0
18 indicatorOfUnitOfTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
19-22 forecastTime = 0
23 typeOfFirstFixedSurface = 1 [Ground or water surface (grib2/tables/2/4.5.table) ]
24 scaleFactorOfFirstFixedSurface = 0
25-28 scaledValueOfFirstFixedSurface = 1
29 typeOfSecondFixedSurface = 255 [Missing (grib2/tables/2/4.5.table) ]
30 scaleFactorOfSecondFixedSurface = 0
31-34 scaledValueOfSecondFixedSurface = 0
====================== SECTION_5 ( length=23, padding=0 ) ======================
1-4 section5Length = 23
5 numberOfSection = 5
6-9 numberOfValues = 145543
10-11 dataRepresentationTemplateNumber = 40 [JPEG2000 Packing (grib2/tables/2/5.0.table) ]
12-15 referenceValue = -2278
16-17 binaryScaleFactor = 0
18-19 decimalScaleFactor = 2
20 bitsPerValue = 13
21 typeOfOriginalFieldValues = 0 [Floating point (grib2/tables/2/5.1.table) ]
22 typeOfCompressionUsed = 0 [Lossless (grib2/tables/2/5.40.table) ]
23 targetCompressionRatio = 255
====================== SECTION_6 ( length=30246, padding=0 ) ======================
1-4 section6Length = 30246
5 numberOfSection = 6
6 bitMapIndicator = 0 [A bit map applies to this product and is specified in this Section (grib2/tables/2/6.0.table) ]
7-30246 bitmap = 30240 {
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00, 00,
00, 00, 00, 00
... 30140 more values
} # g2bitmap bitmap
====================== SECTION_7 ( length=149292, padding=0 ) ======================
1-4 section7Length = 149292
5 numberOfSection = 7
6-149292 codedValues = (145543,149287) {
-6.2600000000e+00, -6.3000000000e+00, -6.3300000000e+00, -6.3300000000e+00, -6.3500000000e+00, -6.4300000000e+00, -6.5300000000e+00, -6.6800000000e+00,
-6.8400000000e+00, -7.0500000000e+00, -7.3700000000e+00, -7.7800000000e+00, -8.1500000000e+00, -8.3800000000e+00, -8.4300000000e+00, -8.3400000000e+00,
-8.1600000000e+00, -7.9500000000e+00, -7.6900000000e+00, -7.4200000000e+00, -7.2200000000e+00, -7.0900000000e+00, -6.9800000000e+00, -6.8700000000e+00,
-6.7900000000e+00, -6.7500000000e+00, -6.7200000000e+00, -6.6900000000e+00, -6.6700000000e+00, -6.6800000000e+00, -6.7200000000e+00, -6.8000000000e+00,
-6.8800000000e+00, -6.9300000000e+00, -6.9500000000e+00, -6.9300000000e+00, -6.8400000000e+00, -6.6900000000e+00, -6.4800000000e+00, -6.2300000000e+00,
-5.9700000000e+00, -5.7400000000e+00, -5.5000000000e+00, -5.3200000000e+00, -5.2100000000e+00, -5.1700000000e+00, -5.2000000000e+00, -5.3100000000e+00,
-5.4800000000e+00, -5.6800000000e+00, -5.9100000000e+00, -6.0800000000e+00, -6.2500000000e+00, -6.3400000000e+00, -6.3200000000e+00, -6.2000000000e+00,
-5.9700000000e+00, -5.6000000000e+00, -5.1400000000e+00, -4.6200000000e+00, -4.1000000000e+00, -3.5600000000e+00, -3.1000000000e+00, -2.7100000000e+00,
-2.3900000000e+00, -2.1500000000e+00, -2.0400000000e+00, -2.1100000000e+00, -2.2800000000e+00, -2.4700000000e+00, -2.6200000000e+00, -2.6600000000e+00,
-2.5700000000e+00, -2.3100000000e+00, -1.9000000000e+00, -1.3600000000e+00, -7.8000000000e-01, -2.4000000000e-01, 2.1000000000e-01, 5.3000000000e-01,
6.7000000000e-01, 6.1000000000e-01, 4.0000000000e-01, 1.2000000000e-01, -2.0000000000e-01, -5.2000000000e-01, -8.1000000000e-01, -1.0700000000e+00,
-4.5700000000e+00, -1.5600000000e+00, -2.8500000000e+00, -2.8100000000e+00, -7.1000000000e-01, -5.9000000000e-01, -2.0800000000e+00, -2.9300000000e+00,
-5.9000000000e+00, -6.0100000000e+00, -6.1600000000e+00, -6.2800000000e+00
... 145443 more values
} # data_jpeg2000_packing codedValues
====================== SECTION_8 ( length=4, padding=0 ) ======================
1-4 7777 = 7777