NBM v3.1 GRIB2 Encoding

This web page seeks to provide users with some of the settings we are using to encode National Blend of Models products in GRIB2. The sections that follow list the contents of the GRIB2 bulletin, octet by octet. In many cases, coding differs by element and/or region. Therefore, coding used is listed according to those variations. This information can also be read and extracted for each GRIB2 file using the degrib reader program. Users should consult the WMO's GRIB2 handbook for the complete details on GRIB2 encoding.

 

Elements

A list of the NBM weather elements available in grib2 format can be found on the NBM Grib2 Element List

IS0: Indicator Section

IS0 Groups

Standard(all except maxffwi,maxhi,sigwv)maxffwi/maxhisigwv

 

Standard

octet(s) octet content value description
1-4 "grib" definition 1196575042  
5-6 reserved    
7 discipline 0 meteorological
8 grib edition number 2  
9 total length of grib message in octets varies  

maxffwi/maxhi

octet(s) octet content value description
1-4 "grib" definition 1196575042  
5-6 reserved    
7 discipline 2 land surface
8 grib edition number 2  
9 total length of grib message in octets varies  

sigwv

octet(s) octet content value description
1-4 "grib" definition 1196575042  
5-6 reserved    
7 discipline 10 oceanographic
8 grib edition number 2  
9 total length of grib message in octets varies  

IS1: Identification Section

IS1 GROUPS

standard (all except dryts03),dryts03

 

Standard

octet(s) octet content value description
1-4 length of section in octets 21  
5 section number 1  
6-7 ID of originating center 7 National Weather Service - NCEP
8-9 ID of origin sub-center 14 MDL
10 GRIB master tables version number ** 1  
11 GRIB local tables' version number 0 Local tables not used
12 significance of reference time 1 start of forecast
13-14 Year varies  
15 Month varies  
16 Day varies  
17 Hour 0  
18 Minute 0  
19 Second 0  
20 Production Status of Processed data in the GRIB message 0 operational product
21 Type of processed data in this GRIB message 1 forecast products

Note

**Previously NBM v3.1 used Master Table number 19. Due to a bug, old versions of degrib may not be able to read the new nbm grib files that use Grib Master Table 19. Please update to the newest version of degrib to read the older files. To download, go to our Degrib Page

dryts03

octet(s) octet content value description
1-4 length of section in octets 21  
5 section number 1  
6-7 ID of originating center 7 National Weather Service - NCEP
8-9 ID of origin sub-center 9 US National Weather Service - Other (WMC)
10 GRIB master tables version number 2 Version Implemented on 4 November 2003
11 GRIB local tables' version number 1 local table version 1 used
12 significance of reference time 1 start of forecast
13-14 Year varies  
15 Month varies  
16 Day varies  
17 Hour 0  
18 Minute 0  
19 Second 0  
20 Production Status of Processed data in the GRIB message 1 operational test product
21 Type of processed data in this GRIB message 1 forecast products

 

IS2: Local Use Section

Standard (all except predomwx)

 

Do not use Section 2. All values are 0. 

 

predomwx

octet(s) octet content value description
1-4 Length of the section in octets varies  
5 Number of the section 2  
6 Local Use Format 1 MDL Local Use Template 2.1

 

 

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