GMOS GRIB

Gridded MOS GRIB2 Encoding Details

General

The GFS-based Gridded MOS guidance is provided on the 2.5 km CONUS NDFD (experimentally), 5km CONUS NDFD, 3km Alaska NDFD, and 2.5km Hawaii NDGD grids in GRIB2 format. The products are disseminated via two mechanisms. GRIB2 files are currently available on the NWS FTP server. Descriptions of the file locations and names (PDF) are available. The files on the ftp server contain multiple grids in each file, grouped by element. The gridded MOS products are also officially disseminated via the NWS Satellite Broadcast Network (SBN) and NOAAPORT. The guidance is sent with each grid as a separate product with its own unique WMO header. See the list below for links to WMO headers for each domain.

This webpage seeks to provide users with some of the settings we are using to encode our products in GRIB2. Users should consult the WMO's GRIB2 handbook for the complete details on GRIB2 encoding.

Section 0 - Indicator Section

For all Gridded MOS GRIB2 prodcuts we set octet 7, Discipline, to 0 for Meteorological. We use GRIB edition 2 in octet 8.
 

Section 1 - Identification Section

Select Octet No. Value Explanation
6-7 7 Originating Center - NCEP
8-9 14 Originating Sub-center - MDL
10 1 initial operational version number
11 0 Version of local tables
12 1 Significance of date in Octets 13-19
13-19 Year, Month, Day, Hr, Min, Sec Date of model run on which guidance is based
20 0 Operational products
21 1 Forecast products

 

Section 2 - Local Use Section

For the Gridded MOS element weather, MDL GRIB2 encoding software uses the Local Use section for packing metadata unique to each grid. At this time, for parameters other than weather, t he Local Use section is omitted. For more information on weather and MDL use of the Local Use section, see: www.weather.gov/mdl/gmos_grib2_wxinfo

Section 3 - Grid Definition Section

The Gridded MOS guidance is presented on the 2.5-km NDFD grid and 5-km NDFD grid for the CONUS; 3-km NDFD grid for Alaska; and 2.5-km NDFD grid for Hawaii. The following are the grid specifications used to pack the guidance into GRIB2.

2.5km CONUS grid -- Image coming soon

Select Octet No. Value Explanation
1-4 TBD Length of section in octets
5 3 Number of Section
6 0 Grid definition template defined in Octet 13-14
7-10 2953665 Number of data points
11 0 Number of non-rectangular points
12 0 No appended list of points
13-14 30 Lambert Conformal GDT
15 1 Spherical earth, radius in Octet 16-20
16 0 Scale factor of radius of spherical earth
17-20 6371200 Scaled value of radius of spherical earth
21 missing  
22-25 missing  
26 missing  
27-30 missing  
31-34 2145 NX
35-38 1377 NY
39-42 20192000 Latitude of first grid point
43-46 238446000 Longitude of first grid point
47 48 Resolution and component flags
48-51 25000000 Latitude where Dx and Dy are specified
52-55 265000000 Longitude of parallel meridian
56-59 2539703 Dx - grid length in x direction
60-63 2539703 Dy - grid length in y direction
64 0 Projection centre flag
65 80 data scanned boustrophedonically
66-69 25000000 Latin 1
70-73 25000000 Latin 2
74-77 -90000000 Latitude of southern pole
78-81 0 Longitude of southern pole

 

5km CONUS grid (click for image)

Select Octet No. Value Explanation
1-4 TBD Length of section in octets
5 3 Number of Section
6 0 Grid definition template defined in Octet 13-14
7-10 739297 Number of data points
11 0 Number of non-rectangular points
12 0 No appended list of points
13-14 30 Lambert Conformal GDT
15 1 Spherical earth, radius in Octet 16-20
16 0 Scale factor of radius of spherical earth
17-20 6371200 Scaled value of radius of spherical earth
21 missing  
22-25 missing  
26 missing  
27-30 missing  
31-34 1073 NX
35-38 689 NY
39-42 20192000 Latitude of first grid point
43-46 238446000 Longitude of first grid point
47 48 Resolution and component flags
48-51 25000000 Latitude where Dx and Dy are specified
52-55 265000000 Longitude of parallel meridian
56-59 5079406 Dx - grid length in x direction
60-63 5079406 Dy - grid length in y direction
64 0 Projection centre flag
65 80 data scanned boustrophedonically
66-69 25000000 Latin 1
70-73 25000000 Latin 2
74-77 -90000000 Latitude of southern pole
78-81 0 Longitude of southern pole

 

3km Alaska grid (click for image)

Select Octet No. Value Explanation
1-4 TBD Length of section in octets
5 3 Number of Section
6 0 Grid definition template defined in Octet 13-14
7-10 1822145 Number of data points
11 0 Number of non-rectangular points
12 0 No appended list of points
13-14 20 Polar Stereographic GDT
15 1 Spherical earth, radius in Octet 16-20
16 0 Scale factor of radius of spherical earth
17-20 6371200 Scaled value of radius of spherical earth
21 missing  
22-25 missing  
26 missing  
27-30 missing  
31-34 1649 NX
35-38 1105 NY
39-42 40530100 Latitude of first grid point
43-46 181429000 Longitude of first grid point
47 0 Resolution and component flags
48-51 60000000 Latitude where Dx and Dy are specified
52-55 210000000 Orientation of the grid
56-59 2976560 Dx - grid length in x direction
60-63 2976560 Dy - grid length in y direction
64 0 Projection centre flag
65 80 data scanned boustrophedonically

 

2.5km Hawaii grid (click for image)

Select Octet No. Value Explanation
1-4 TBD Length of section in octets
5 3 Number of Section
6 0 Grid definition template defined in Octet 13-14
7-10 350625 Number of data points
11 0 Number of non-rectangular points
12 0 No appended list of points
13-14 10 Mercator
15 1 Spherical earth, radius in Octet 16-20
16 0 Scale factor of radius of spherical earth
17-20 6371200 Scaled value of radius of spherical earth
21 missing  
22-25 missing  
26 missing  
27-30 missing  
31-34 625 NX
35-38 561 NY
39-42 14351500 Latitude of first grid point
43-46 195030500 Longitude of first grid point
47 0 Resolution and component flags
48-51 20000000 Latitude where Dx and Dy are specified
52-55 26860500 Latitude of last grid point
56-59 209959800 Longitude of last grid point
60 64 Scanning Mode
61-64 0 Orientation of the grid, angle between i direction and the Equator
65-68 2500000 Dx - grid length in x direction
69-72 2500000 Dy - grid length in y direction

 

Section 4 - Product Definition Section

The Gridded MOS products are packed using either Product Definition Template (PDT) 4.0, 4.8, or 4.9. The following tables list the settings for each element.

Guidance Valid at a Point in Time - PDT 4.0

Octet No. 2-M Temperature (K) 2-M Dewpoint (K) Relative Humidity (%) Wind Speed (m/s) Wind Direction (degrees) Wind Gusts (m/s) Opaque Sky Cover (%) Weather
1-4 Length of section in octets
5 4
6-7 0
8-9 0
10 0 0 1 2 2 2 6 1
11 0 6 1 1 0 22 1 226
12 2
13 missing
14 96
15-16 missing
17 missing
18 1
19-22 hours from reference time to valid time (i.e. projection)
23 103 103 103 103 103 103 1 1
24 0
25-28 2 2 2 10 10 10 0 0
29 missing
30 0
31-34 0

 

Guidance Valid Over a Period of Time - PDT 4.8 (see below for POPs)

Octet No. Maximum Temperature (K) Minimum Temperature (K) Snowfall Amt (m) 3-hr tstm (%) 6-hr tstm (%) 12-hr tstm (%) 6-hr Precip Amount (kg/m*2) 12-hr Precip Amount (kg/m*2)
1-4 Length of section in octets
5 4
6-7 0
8-9 8
10 0 0 1 19 19 19 1 1
11 4 5 29 2 2 2 8 8
12 2 2 2 5 5 5 2 2
13 missing
14 96
15-16 missing
17 missing
18 1
19-22 hours from reference time to beginning of forecast period
23 103 103 1 1 1 1 1 1
24 0
25-28 2 2 0 0 0 0 0 0
29 missing
30 0
31-34 0
35-36 Year of end of forecast period
37 Month of end of forecast period
38 Day of end of forecast period
39 Hour of end of forecast period
40 Minute of end of forecast period
41 Second of end of forecast period
42 0 (1 for Hawaii GMOS). Future updates to GMOS will change this value to 1 also. 1
43-46 0
47 missing 1 missing 1
48 missing
49 missing 1
50-53 missing 24 3 6 12 6 12
54 missing
55-58 missing

 

Guidance Valid Over a Period of Time - PDT 4.9 -- POPs

Octet No. 6-hr POP (%) 12-hr POP (%)
1-4 Length of section in octets
5 4
6-7 0
8-9 9
10 1
11 8
12 2
13 missing
14 96
15-16 missing
17 missing
18 1
19-22 hours from reference time to beginning of forecast period
23 1
24 0
25-28 0
29 missing
30 0
31-34 0
35 missing
36 missing
37 1
38 missing
39-42 missing
43 3
44-47 254
48-49 Year of end of forecast period
50 Month of end of forecast period
51 Day of end of forecast period
52 Hour of end of forecast period
53 Minute of end of forecast period
54 Second of end of forecast period
55 1
56-59 0
60 1
61 missing
62 1
63-66 6 12
67 1
68 0

 

Section 5 - Data Representation Section


We use Data Representation Template 5.3: Gridpoint data - complex packing and spatial differencing. All fields are packed as floating point values except for wind direction which is packed as an integer.

For scaling, we use the following decimal scaling factors:

Temperatures Wind Speed/Gusts Wind Direction Percentages (POP, RH and Opaque Sky) Precipitation Amt Snowfall Amt Weather
1 1 0 0 3 5 0

Binary scaling will be used only for the 2.5 km CONUS grids. Learn more about binary scaling here. The following binary scaling factors will be used.

Temperatures Wind Speed/Gusts
2 2

MOS