WXP
Appendix

GRIB Format

Edition 1

1. GRIB Overview

The GRIB product is broken down into several subsections:

Tables:

Each section is described below.

1.1 Data Packing

The values saved in a GRIB file are packed.  The actual data value is derived from the following parameters:

Each gridpoint value (Y)  is determined from the following formula:

Y * 10D = R + (X * 2E)

The reference value (R) uses IBM single precision floating point format.

sAAAAAAA BBBBBBBB BBBBBBBB BBBBBBBB

The appropriate formula to recover the value of R is:

R = (-1)s * 2(-24) * B * 16(A-64)

2. Indicator Section

Byte/Octet Description
01-04 "GRIB" - ASCII characters to flag data as GRIB data
05-07 Total number of bytes for all data
08 GRIB edition - currently 1

2. Product Definition Section (PDS)

Octet/Byte Description
01-03 Length in bytes of PDS
04 Parameter table version number - currently 2 for international exchange
05 Originating Center
06 Generating process or model ID (center dependent)
07 Grid identification - used for fixed grid types, GDS is used for specific grid definition
08 Flag specifying the presence or absence of a GDS or a BMS
09 Parameter and units
10 Level or Layer Type
11-12 Level or Layer values
13 Initial or Reference Time (octet 13-17) - Year of century
14 Month of year
15 Day of month
16 Hour of day
17 Minute of hour
18 Forecast time unit
19 P1 - Period of time (Number of time units). 0 for analysis or initialized analysis.
20 P2 - Period of time (Number of time units) or time interval between successive analyses, successive initialized analyses, or forecasts, undergoing averaging or accumulation.
21 Time range indicator
22-23 Number included in average, when octet 21 (Table 5) indicates an average or accumulation; otherwise set to zero.
24 Number Missing from averages or accumulations.
25 Century of Initial (Reference) time (=20 until Jan. 1, 2001, 21 afterwards)
26 Identification of sub-center
27-28 The decimal scale factor D. A negative value is indicated by setting the high order bit (bit No. 1) in octet 27 to 1 (on).
29-40 Reserved (need not be present)
41-nnn Reserved for originating center use. (See Appendix C for information on NCEP's use of these octets for ensemble modeling.)

Note (1): Octet 8 may indicate the presence of the Grid Description Section (GDS) even though octet 7 specifies a predefined grid. In this case the GDS must describe that grid - this device serves as a mechanism for transmitting new "predefined" grids to users prior to their formal publication in this or the official WMO documentation. It is, however, the desired practice to always include the GDS in GRIB bulletins.

Note (2): The use of octet 26 to indicate a "sub-center" is now an officially sanctioned WMO practice. The use arises out of a recent change in the Manual in which the "originating center" for both GRIB and BUFR (FM 94) reference a single common table (WMO No. 306, Part C, Table C-1). The WMO will coordinate the assignment of the originating center numbers for national and international centers for both GRIB and BUFR, while each national center will then be free to assign sub-center numbers at will to be placed in the octet 26 of the GRIB PDS (or Octet 5 of BUFR Section 1). A zero value in octet 26 will serve as the default indicating that there is no sub-center associated with a particular center. Table 0, in this document, shows, in Part 1, the WMO recognized originating centers as would be found in octet 5, and, additionally, in Part 2, sub-center numbers allocated by NCEP.

Note (3): The NCEP Central Operations' (NCO) entries in the local use sections of Tables 2 and 6, as well as all NCO-defined tables, are specified in this Office Note. 

Note (4): The NCEP currently uses three values for the parameter table version number (PDS octet 4), version number 2 and the new version numbers 129 and 130. Both of these tables are specified in this Office Note.

3. Grid Description Section (GDS)

Byte/Octet Description
01-03 Length in bytes of the GDS
04 NV, the number of vertical coordinate parameters
05 PV, the location (octet number) of the list of vertical coordinate parameters, if present or PL, the location (octet number) of the list of numbers of points in each row (when no vertical parameters are present), if present or (all bits set to 1) if neither are present
06 Data representation type
07-32 Grid description, according to data representation type, except Lambert, Mercator or Space View.
07-42 Grid description for Lambert or Mercator grid
07-44 Grid description for Space View perspective grid
PV List of vertical coordinate parameters. length = NV x 4 octets; if present, then PL = 4 x NV + PV
PL List of numbers of points in each row, used for quasi-regular grids. length = NROWS x 2 octets, where NROWS is the total number of rows defined within the grid description

Note: NV and PV relate to features of GRIB not, at present, in use in international exchange. See the WMO Manual on Codes for the descriptions of those features.

PL is used for "quasi-regular" or "thinned" grids; e.g., a lat/lon grid where the number of points in each row is reduced as one moves poleward from the equator. The reduction usually follows some mathematical formula involving the cosine of the latitude, to generate an (approximately) equally spaced grid array. The association of the numbers in octet PL (and following) with the particular row follows the scanning mode specification in Table 8.

3.1 Grid Definition for Latitude/Longitude Grids

Octet/Byte Description
07-08 Ni - No. of points along a latitude circle
09-10 Nj - No. of points along a longitude meridian
11-13 La1 - latitude of first grid point units: millidegrees (degrees x 1000)
values limited to range 0 - 90,000 bit 1 (leftmost) set to 1 for south latitude
14-16 Lo1 - longitude of first grid point units: millidegrees (degrees x 1000)
values limited to range 0 - 360,000 bit 1 (leftmost) set to 1 for west longitude
17 Resolution and component flags
18-20 La2 - Latitude of last grid point (same units, value range, and bit 1 as La1)
21-23 Lo2 - Longitude of last grid point (same units, value range, and bit 1 as Lo1)
24-25 Di - Longitudinal Direction Increment (same units as Lo1) (if not given, all bits set = 1)
26 - 27 Regular Lat/Lon Grid:
Dj - Latitudinal Direction Increment (same units as La1) (if not given, all bits set = 1)
Gaussian Grid:
N - number of latitude circles between a pole and the equator. Mandatory if Gaussian Grid specified
28 Scanning mode flags
29 - 32 Reserved (set to zero)

Notes:

3.2 Grid Definition for Polar Stereographic Grids

Octet Description
07-08 Nx - Number of points along x-axis
09-10 Ny - Number of points along y-axis
11-13 La1 - Latitude of first grid point
14-16 Lo1 - Longitude of first grid point
17 Resolution and component flags
18-20 Lov - The orientation of the grid; i.e., the east longitude value of the meridian which is parallel to the y-axis (or columns of the grid) along which latitude increases as the y-coordinate increases. (Note: The orientation longitude may, or may not, appear within a particular grid.)
21-23 Dx - the X-direction grid length (see note 2)
24-26 Dy - the Y-direction grid length (see note 2)
27 Projection center flag (see note 5)
28 Scanning mode
29 - 32 Set to 0 (reserved)

Notes:

  1. Latitude and longitude are in millidegrees (thousandths)
  2. Grid lengths are in units of meters, at the 60 degree latitude circle nearest to the pole in the projection plane.
  3. Latitude values are limited to the range 0 - 90,000. Bit 1 is set to 1 to indicate south latitude.
  4. Longitude values are limited to the range 0 - 360,000. Bit one is set to 1 to indicate west longitude.
  5. Projection Center Flag - Bit 1 set to 0 if the North pole is on the projection plane. Bit 1 set to 1 if the South pole is on the projection plane.
  6. The first and last grid points may not necessarily be the same as the first and last data points if the bit map section (BMS) is used.
  7. The resolution flag (bit 1 of Table 7) is not applicable.

3.3 Grid Definition for Lambert Conformal, Conic Grids

Octet Description
07-08 Nx - Number of points along x-axis
09-10 Ny - Number of points along y-axis
11-13 La1 - Latitude of first grid point
14-16 Lo1 - Longitude of first grid point
17 Resolution and component flags
18-20 Lov - The orientation of the grid; i.e., the east longitude value of the meridian which is parallel to the y-axis (or columns of the grid) along which latitude increases as the y-coordinate increases. (Note: The orientation longitude may, or may not, appear within a particular grid.)
21-23 Dx - the X-direction grid length (see note 2)
24-26 Dy - the Y-direction grid length (see note 2)
27 Projection center flag (see note 5)
28 Scanning mode
29-31 Latin 1 - The first latitude from the pole at which the secant cone cuts the spherical earth. (See Note 8)
32-34 Latin 2 - The second latitude from the pole at which the secant cone cuts the spherical earth. (See Note 8)
35-37 Latitude of southern pole (millidegrees)
38-40 Longitude of southern pole (millidegrees)
41-42 Reserved (set to 0)

Notes:

  1. Latitude and longitude are in millidegrees (thousandths)
  2. Grid lengths are in units of meters, at the intersection latitude circle nearest to the pole in the projection plane.
  3. Latitude values are limited to the range 0 - 90,000. Bit 1 is set to 1 to indicate south latitude.
  4. Longitude values are limited to the range 0 - 360,000. Bit one is set to 1 to indicate west longitude.
  5. Octet 27:
    Bit 1 set to 0 if the North pole is on the projection plane.
    Bit 1 set to 1 if the South pole is on the projection plane.
    Bit 2 set to 0 if only one projection center used
    Bit 2 set to 1 if projection is bipolar and symmetric
  6. The first and last grid points may not necessarily be the same as the first and last data points if the bit map section (BMS) is used.
  7. The resolution flag (bit 1 of Table 7) is not applicable.
  8. If Latin 1 = Latin 2 then the projection is on a tangent cone.

3.4 Grid Definition for Mercator Grids

Octet Description
07-08 Ni - Number of points along a latitude circle
09-10 Nj - Number of points along a longitude meridian
11-13 La1 - Latitude of first grid point
14-16 Lo1 - Longitude of first grid point
17 Resolution and component flags
18-20 La2 - latitude of last grid point
21-23 Lo2 - longitude of last grid point
24-26 Latin - The latitude(s) at which the Mercator projection cylinder intersects the earth.
27 Reserved (set to 0)
28 Scanning mode
29-31 Di - the longitudinal direction increment (see Note 2)
32-34 Dj - the latitudinal direction increment (see note 2)
35-42 Reserved (set to 0)

Notes:

  1. Latitude and longitude are in millidegrees (thousandths)
  2. Grid lengths are in units of meters, at the circle of latitude specified by Latin.
  3. Latitude values are limited to the range 0 - 90,000. Bit 1 is set to 1 to indicate south latitude.
  4. Longitude values are limited to the range 0 - 360,000. Bit one is set to 1 to indicate west longitude.
  5. The latitude and longitude of the last grid point should always be given.
  6. The first and last grid points may not necessarily be the same as the first and last data points if the bit map section (BMS) is used.

3.5 Grid Definition for Space View or Orthographic

Octet Description
07-08 Nx - number of points along x axis (columns)
09-10 Ny - number of points along y axis (rows or lines)
11-13 Lap - latitude of sub-satellite point
14-16 Lop - longitude of sub-satellite point
17 Resolution and component flags (Table 7)
18-20 dx - apparent diameter of earth in grid lengths, in x direction
21-23 dy - apparent diameter of earth in grid lengths, in y direction
24-25 Xp - X-coordinate of sub satellite point
26-27 Yp - Y-coordinate of sub-satellite point
28 Scanning Mode (Table 8)
29-31 the orientation of the grid; i.e., the angle in millidegrees between the increasing y axis and the meridian of the sub-satellite point in the direction of increasing latitude (see Note 3).
32-34 Nr - the altitude of the camera from the earth's center, measured in units of the earth's (equatorial) radius (See Note 4).
35-44 reserved

Notes:

  1. It is assumed that the satellite is at its nominal position, i.e., it is looking directly at its sub-satellite point.
  2. Octet 32-34 shall be set to all ones (missing) to indicate the orthographic view (from infinite distance).
  3. It is the angle between increasing y axis and the meridian 180 degrees east if the sub-satellite point is the North pole; or the meridian 0 degrees, if the sub-satellite point is the south pole.
  4. The apparent angular size of the earth will be given by 2 x asin(1/Nr).
  5. The horizontal and vertical angular resolutions of he sensor (Rx and Ry), needed for navigation equations, can be calculated from the following

Rx = 2 x asin(1/Nr) / dx
Ry = 2 x asin(1/Nr) / dy

4. Bit Map Section (BMS)

This section defines which grid points will be presented in the Binary Data Section.   A 1 value indicates a value will appear.  A 0 value means it will be absent.

Octet Description
01-03 Length in bytes of BMS
04 Number of unused bits at end of Section 3.
05-06 Numeric: if 0: a bit map follows; otherwise: the numeric refers to a predefined bit map provided by the center
07-nnn Bit map, zero filled to an even number of octets

5. Binary Data Section (BDS)

This section contains the packed binary data. 

Octet Description
01-03 Length in octets of binary data section
04 Bits 1 through 4: Flag
Bits 5 through 8: Number of unused bits at end of Section 4.
05-06 The binary scale factor (E). A negative value is indicated by setting the high order bit (bit No. 1) in octet 5 to 1 (on).
07-10 Reference value (minimum value); floating point representation of the number.
11 Number of bits into which a datum point is packed
12-nnn Variable, depending on octet 4; zero filled to an even number of octets.
14 Optionally, may contain an extension of the flags in octet 4.

6. End Section

This is a key sequence used to denote the end of a GRIB product.

Octet Description
1-4 "7777"

Table A. Originating Centers (PDS)

Value Center
01
 Melbourne (WMC)
02
 Melbourne (WMC)
04
 Moscow (WMC)
05
 Moscow (WMC)
07
 US National Weather Service - NCEP (WMC)
08
 US National Weather Service - NWSTG (WMC)
09
 US National Weather Service - Other (WMC)
10
 Cairo (RSMC/RAFC)
12
 Dakar (RSMC/RAFC)
14
 Nairobi (RSMC/RAFC)
16
 Atananarivo (RSMC)
18
 Tunis-Casablanca (RSMC)
20
 Las Palmas (RAFC)
21
 Algiers (RSMC)
22
 Lagos (RSMC)
26
 Khabarovsk (RSMC)
28
 New Delhi (RSMC/RAFC)
30
 Novosibirsk (RSMC)
32
 Tashkent (RSMC)
33
 Jeddah (RSMC)
34
 Japanese Meteorological Agency - Tokyo (RSMC)
36
 Bankok
37
 Ulan Bator
38
 Beijing (RSMC)
40
 Seoul
41
 Buenos Aires (RSMC/RAFC)
43
 Brasilia (RSMC/RAFC)
45
 Santiago
46
 Brasilian Space Agency - INPE
51
 Miami (RSMC/RAFC)
52
 National Hurricane Center, Miami
53
 Canadian Meteorological Service - Montreal (RSMC)
54
 Canadian Meteorological Service - Montreal (RSMC)
55
 San Francisco
57
 U.S. Air Force - Global Weather Center
58
 US Navy - Fleet Numerical Oceanography Center
59
 NOAA Forecast Systems Lab, Boulder CO
60
 National Center for Atmospheric Research (NCAR), Boulder, CO
64
 Honolulu
65
 Darwin (RSMC)
67
 Melbourne (RSMC)
69
 Wellington (RSMC/RAFC)
74
 U.K. Met Office - Bracknell
76
 Moscow (RSMC/RAFC)
78
 Offenbach (RSMC)
80
 Rome (RSMC)
82
 Norrkoping
85
 French Weather Service - Toulouse
86
 Helsinki
87
 Belgrade
88
 Oslo
89
 Prague
90
 Episkopi
91
 Ankara
92
 Frankfurt/Main (RAFC)
93
 London (WAFC)
94
 Copenhagen
95
 Rota
96
 Athens
97
 European Space Agency (ESA)
98
 European Center for Medium-Range Weather Forecasts - Reading
99
 DeBilt, Netherlands

B. Process/Model ID

NCEP values:

Value Model
02
 Ultra Violet Index Model
03
 NCEP/ARL Transport and Dispersion Model1 
05
 Satellite Derived Precipitation and temperatures, from IR (See PDS Octet 41... for specific satellite ID)
10
 Global Wind-Wave Forecast Model
19
 Limited-area Fine Mesh (LFM) analysis
25
 Snow Cover Analysis
30
 Forecaster generated field
31
 Value added post processed field
39
 Nested Grid forecast Model (NGM)
42
 Global Optimum Interpolation Analysis (GOI) from "Aviation" run
43
 Global Optimum Interpolation Analysis (GOI) from "Final" run 
44
 Sea Surface Temperature Analysis
45
 Coastal Ocean Circulation Model
49
 Ozone Analysis from TIROS Observations 
52
 Ozone Analysis from Nimbus 7 Observations 
53
 LFM-Fourth Order Forecast Model
64
 Regional Optimum Interpolation Analysis (ROI)
68
 80 wave triangular, 18-layer Spectral model from "Aviation" run
69
 80 wave triangular, 18 layer Spectral model from "Medium Range Forecast" run
70
 Quasi-Lagrangian Hurricane Model (QLM)
73
 Fog Forecast model - Ocean Prod. Center
74
 Gulf of Mexico Wind/Wave
75
 Gulf of Alaska Wind/Wave
76
 Bias corrected Medium Range Forecast
77
 126 wave triangular, 28 layer Spectral model from "Aviation" run
78
 126 wave triangular, 28 layer Spectral model from "Medium Range Forecast" run
79
 Backup from the previous run
80
 62 wave triangular, 28 layer Spectral model from "Medium Range Forecast" run
81
 Spectral Statistical Interpolation (SSI) analysis from "Aviation" run. 
82
 Spectral Statistical Interpolation (SSI) analysis from "Final" run.
83
 No longer used
84
 MESO ETA Model (currently 12 km)
85
 No longer used
86
 RUC Model, from Forecast Systems Lab (isentropic; scale: 60km at 40N)
87
 CAC Ensemble Forecasts from Spectral (ENSMB)
88
 NOAA Wave Watch III (NWW3) Ocean Wave Model
89
 Non-hydrostatic Meso Model (NMM) Currently 8 km)
90
 62 wave triangular, 28 layer spectral model extension of the "Medium Range Forecast" run
91
 62 wave triangular, 28 layer spectral model extension of the "Aviation" run
92
 62 wave triangular, 28 layer spectral model run from the "Medium Range Forecast" final analysis
93
 62 wave triangular, 28 layer spectral model run from the T62 GDAS analysis of the "Medium Range Forecast" run
94
 T170/L42 Global Spectral Model from MRF run
95
 T126/L42 Global Spectral Model from MRF run
96
 Global Forecast System Model (formerly known as the Aviation)
T254 - Forecast hours 00-84
T170 - Forecast hours 87-180
T126 - Forecast hours 192 - 384
100
 RUC Surface Analysis (scale: 60km at 40N)
101
 RUC Surface Analysis (scale: 40km at 40N)
105
 RUC Model from FSL (isentropic; scale: 20km at 40N)
110
 ETA Model - 15km version
120
 Ice Concentration Analysis
121
 Western North Atlantic Regional Wave Model
122
 Alaska Waters Regional Wave Model
123
 North Atlantic Hurricane Wave Model
124
 Eastern North Pacific Regional Wave Model
125
 North Pacific Hurricane Wave Model
126
 Sea Ice Forecast Model
127
 Lake Ice Forecast Model
128
 Global Ocean Forecast Model
130
 Merge of fields from the RUC, Eta, and Spectral Model 
140
 North American Regional Reanalysis (NARR)
141
 Land Data Assimilation and Forecast System
150
 NWS River Forecast System (NWSRFS)
151
 NWS Flash Flood Guidance System (NWSFFGS)
152
 WSR-88D Stage II Precipitation Analysis
153
 WSR-88D Stage III Precipitation Analysis
180
 Quantitative Precipitation Forecast generated by NCEP
181
 River Forecast Center Quantitative Precipitation Forecast mosaic generated by NCEP
182
 River Forecast Center Quantitative Precipitation estimate mosaic generated by NCEP
183
 NDFD product generated by NCEP/HPC
190
 National Convective Weather Diagnostic generated by NCEP/AWC
191
 Current Icing Potential automated product genterated by NCEP/AWC
200
 CPC Manual Forecast Product
210
 EPA Air Quality Forecast

C. Grid Indentifiers

International Exchange Grids

Value

Resolution
degree
lonxlat

Area
Coverage

Grid Shape
Row/Columns

Gridpoints

21

5.0 x 2.5

0-180E, 0-90N

37

36 + pole

1333

22

5.0 x 2.5

180W-0, 0-90N

37

36 + pole

1333

23

5.0 x 2.5

0-180E, 90S-0

pole + 37

36

1333

24

5.0 x 2.5

180W-0, 90S-0

pole + 37

36

1333

25

5.0 x 5.0

0-355E, 0-90N

72

18 + pole

1297

26

5.0 x 5.0

0-355E, 90S-0

pole + 72

18

1297

61

2.0 x 2.0

0-180E, 0-90N

91

45 + pole

4096

62

2.0 x 2.0

180W-0, 0-90N

91

45 + pole

4096

63

2.0 x 2.0

0-180E, 90S-0

pole + 91

45

4096

64

2.0 x 2.0

180W-0, 90S-0

pole + 91

45

4096

255

 (non-standard grid - defined in the GDS)

D. GDS/BMS Flag

Bit Value Meaning
1 0 GDS Omitted
  1 GDS Included
2 0 BMS Omitted
  1 BMS Included
3-8 0 reserved

E. Parameter and Units

Value Parameter Units Abbrev.
000
 Reserved
-
-
001
 Pressure Pa PRES
002
 Pressure reduced to MSL Pa PRMSL
003
 Pressure tendency Pa/s PTEND
004
 Potential vorticity Km2/kg/s PVORT
005
 ICAO Standard Atmosphere Reference Height m ICAHT
006
 Geopotential m2/s2 GP
007
 Geopotential height gpm HGT
008
 Geometric height m DIST
009
 Standard deviation of height m HSTDV
010
 Total ozone Dobson TOZNE
011
 Temperature K TMP
012
 Virtual temperature K VTMP
013
 Potential temperature K POT
014
 Pseudo-adiabatic potential temperature
or equivalent potential temperature		 K EPOT
015
 Maximum temperature K T MAX
016
 Minimum temperature K T MIN
017
 Dew point temperature K DPT
018
 Dew point depression (or deficit) K DEPR
019
 Lapse rate K/m LAPR
020
 Visibility m VIS
021
 Radar Spectra (1)
-
 RDSP1
022
 Radar Spectra (2)
-
 RDSP2
023
 Radar Spectra (3)
-
 RDSP3
024
 Parcel lifted index (to 500 hPa) K PLI
025
 Temperature anomaly K TMP A
026
 Pressure anomaly Pa PRESA
027
 Geopotential height anomaly gpm GP A
028
 Wave Spectra (1)
-
 WVSP1
029
 Wave Spectra (2)
-
 WVSP2
030
 Wave Spectra (3)
-
 WVSP3
031
 Wind direction (from which blowing) deg true WDIR
032
 Wind speed m/s WIND
033
 u-component of wind m/s U GRD
034
 v-component of wind m/s V GRD
035
 Stream function m2/s STRM
036
 Velocity potential m2/s V POT
037
 Montgomery stream function m2/s2 MNTSF
038
 Sigma coordinate vertical velocity /s SGCVV
039
 Vertical velocity (pressure) Pa/s V VEL
040
 Vertical velocity (geometric) m/s DZDT
041
 Absolute vorticity /s ABS V
042
 Absolute divergence /s ABS D
043
 Relative vorticity /s REL V
044
 Relative divergence /s REL D
045
 Vertical u-component shear /s VUCSH
046
 Vertical v-component shear /s VVCSH
047
 Direction of current Degree true DIR C
048
 Speed of current m/s SP C
049
 u-component of current m/s UOGRD
050
 v-component of current m/s VOGRD
051
 Specific humidity kg/kg SPF H
052
 Relative humidity % R H
053
 Humidity mixing ratio kg/kg MIXR
054
 Precipitable water kg/m2 P WAT
055
 Vapor pressure Pa VAPP
056
 Saturation deficit Pa SAT D
057
 Evaporation kg/m2 EVP
058
 Cloud Ice kg/m2 C ICE
059
 Precipitation rate kg/m2/s PRATE
060
 Thunderstorm probability % TSTM
061
 Total precipitation kg/m2 A PCP
062
 Large scale precipitation (non-conv.) kg/m2 NCPCP
063
 Convective precipitation kg/m2 ACPCP
064
 Snowfall rate water equivalent kg/m2/s SRWEQ
065
 Water equiv. of accum. snow depth kg/m2 WEASD
066
 Snow depth m SNO D
067
 Mixed layer depth m MIXHT
068
 Transient thermocline depth m TTHDP
069
 Main thermocline depth m MTHD
070
 Main thermocline anomaly m MTH A
071
 Total cloud cover % T CDC
072
 Convective cloud cover % CDCON
073
 Low cloud cover % L CDC
074
 Medium cloud cover % M CDC
075
 High cloud cover % H CDC
076
 Cloud water kg/m2 C WAT
077
 Best lifted index (to 500 hPa) K BLI
078
 Convective snow kg/m2 SNO C
079
 Large scale snow kg/m2 SNO L
080
 Water Temperature K WTMP
081
 Land cover (land=1, sea=0) (see note) proportion LAND
082
 Deviation of sea level from mean m DSL M
083
 Surface roughness m SFC R
084
 Albedo % ALBDO
085
 Soil temperature K TSOIL
086
 Soil moisture content kg/m2 SOIL M
087
 Vegetation % VEG
088
 Salinity kg/kg SALTY
089
 Density kg/m3 DEN
090
 Water runoff kg/m2 WATR
091
 Ice cover (ice=1, no ice=0) (See Note) proportion ICE C
092
 Ice thickness m ICETK
093
 Direction of ice drift deg. true DICED
094
 Speed of ice drift m/s SICED
095
 u-component of ice drift m/s U ICE
096
 v-component of ice drift m/s V ICE
097
 Ice growth rate m/s ICE G
098
 Ice divergence /s ICE D
099
 Snow melt kg/m2 SNO M
100
 Significant height of combined wind
waves and swell		 m HTSGW
101
 Direction of wind waves (from which) Degree true WVDIR
102
 Significant height of wind waves m WVHGT
103
 Mean period of wind waves s WVPER
104
 Direction of swell waves Degree true SWDIR
105
 Significant height of swell waves m SWELL
106
 Mean period of swell waves s SWPER
107
 Primary wave direction Degree true DIRPW
108
 Primary wave mean period s PERPW
109
 Secondary wave direction Degree true DIRSW
110
 Secondary wave mean period s PERSW
111
 Net short-wave radiation flux (surface) W/m2 NSWRS
112
 Net long wave radiation flux (surface) W/m2 NLWRS
113
 Net short-wave radiation flux (top of atmosphere) W/m2  NSWRT
114
 Net long wave radiation flux (top of atmosphere) W/m2  NLWRT
115
 Long wave radiation flux W/m2  LWAVR
116
 Short wave radiation flux W/m2  SWAVR
117
 Global radiation flux W/m2  G RAD
118
 Brightness temperature K BRTMP
119
 Radiance (with respect to wave number) W/m/sr LWRAD
120
 Radiance (with respect to wave length) W/m3/sr SWRAD
121
 Latent heat net flux W/m2  LHTFL
122
 Sensible heat net flux W/m2  SHTFL
123
 Boundary layer dissipation W/m2  BLYDP
124
 Momentum flux, u component N/m2  U FLX
125
 Momentum flux, v component N/m2  V FLX
126
 Wind mixing energy J WMIXE
127
 Image data
-
 IMG D
128 - 254
 Reserved for use by originating center
-
-

NCEP usage:

Value Parameter Units Abbrev.
128
 Mean Sea Level Pressure
(Standard Atmosphere Reduction)		 Pa MSLSA
129
 Mean Sea Level Pressure
(MAPS System Reduction)		 Pa MSLMA
130
 Mean Sea Level Pressure
(Eta Model Reduction)		 Pa MSLET
131
 Surface lifted index K LFT X
132
 Best (4 layer) lifted index K 4LFTX
133
 K index K K X
134
 Sweat index K S X
135
 Horizontal moisture divergence kg/kg/s MCONV
136
 Vertical speed shear 1/s VW SH
137
 3-hr pressure tendency
Std. Atmos. Reduction		 Pa/s TSLSA
138
 Brunt-Vaisala frequency (squared) 1/s2 BVF 2
139
 Potential vorticity (density weighted) 1/s/m PV MW
140
 Categorical rain (yes=1; no=0) non-dim CRAIN
141
 Categorical freezing rain (yes=1; no=0) non-dim CFRZR
142
 Categorical ice pellets (yes=1; no=0) non-dim CICEP
143
 Categorical snow (yes=1; no=0) non-dim CSNOW
144
 Volumetric soil moisture content fraction SOILW
145
 Potential evaporation rate W/m**2 PEVPR
146
 Cloud workfunction J/kg CWORK
147
 Zonal flux of gravity wave stress N/m**2 U-GWD
148
 Meridional flux of gravity wave stress N/m**2 V-GWD
149
 Potential vorticity m**2/s/kg PV
150
 Covariance between meridional
and zonal components of the wind.
Defined as [uv]-[u][v], where
"[]" indicates the mean over the
indicated time span. 		 m2/s2 COVMZ
151
 Covariance between temperature
and zonal components of the wind.
Defined as [uT]-[u][T], where
"[]" indicates the mean over the
indicated time span. 		 K*m/s COVTZ
152
 Covariance between temperature
and meridional components of the wind.
Defined as [vT]-[v][T], where
"[]" indicates the mean over the
indicated time span. 		 K*m/s COVTM
153
 Cloud water Kg/kg CLWMR
154
 Ozone mixing ratio Kg/kg O3MR
155
 Ground Heat Flux W/m2 GFLUX
156
 Convective inhibition J/kg CIN
157
 Convective Available Potential Energy J/kg CAPE
158
 Turbulent Kinetic Energy J/kg TKE
159
 Condensation pressure of parcel
lifted from indicated surface		 Pa CONDP
160
 Clear Sky Upward Solar Flux W/m2 CSUSF
161
 Clear Sky Downward Solar Flux W/m2 CSDSF
162
 Clear Sky upward long wave flux W/m2 CSULF
163
 Clear Sky downward long wave flux W/m2 CSDLF
164
 Cloud forcing net solar flux W/m2 CFNSF
165
 Cloud forcing net long wave flux W/m2 CFNLF
166
 Visible beam downward solar flux W/m2 VBDSF
167
 Visible diffuse downward solar flux W/m2 VDDSF
168
 Near IR beam downward solar flux W/m2 NBDSF
169
 Near IR diffuse downward solar flux W/m2 NDDSF
170
 Rain water mixing ratio Kg/Kg RWMR
171
 Snow mixing ratio Kg/Kg SNMR
172
 Momentum flux N/m2 M FLX
173
 Mass point model surface non-dim LMH
174
 Velocity point model surface non-dim LMV
175
 Model layer number (from bottom up) non-dim MLYNO
176
 latitude (-90 to +90) deg NLAT
177
 east longitude (0-360) deg ELON
178
 Ice mixing ratio Kg/Kg ICMR
179
 Graupel mixing ratio Kg/Kg GRMR
180
 Surface wind gust m/s GUST
181
 x-gradient of log pressure 1/m LPS X
182
 y-gradient of log pressure 1/m LPS Y
183
 x-gradient of height m/m HGT X
184
 y-gradient of height m/m HGT Y
185
 Turbulence Potential Forecast Index non-dim TPFI
186
 Total Icing Potential Diagnostic non-dim TIPD
187
 Lightning non-dim LTNG
188
 Rate of water dropping from canopy to ground
-
RDRIP
189
 Virtual potential temperature K VPTMP
190
 Storm relative helicity m2/s2 HLCY
191
 Probability from ensemble numeric PROB
192
 Probability from ensemble normalized with
respect to climate expectancy		 numeric PROBN
193
 Probability of precipitation % POP
194
 Percent of frozen precipitation % CPOFP
195
 Probability of freezing precipitation % CPOZP
196
 u-component of storm motion m/s USTM
197
 v-component of storm motion m/s VSTM
198
 Number concentration for ice particles
-
 NCIP
199
 Direct evaporation from bare soil W/m2 EVBS
200
 Canopy water evaporation W/m2 EVCW
201
 Ice-free water surface % ICWAT
202
 Convective weather detection index non-dim CWDI
203
 VAFTAD
-
VAFTD
204
 downward short wave rad. flux W/m2 DSWRF
205
 downward long wave rad. flux W/m2 DLWRF
206
 Ultra violet index
(1 hour integration centered at solar noon)		 J/m2 UVI
207
 Moisture availability % MSTAV
208
 Exchange coefficient (kg/m3)(m/s) SFEXC
209
 No. of mixed layers next to surface integer MIXLY
210
 Transpiration W/m2 TRANS
211
 upward short wave rad. flux W/m2 USWRF
212
 upward long wave rad. flux W/m2 ULWRF
213
 Amount of non-convective cloud % CDLYR
214
 Convective Precipitation rate kg/m2/s CPRAT
215
 Temperature tendency by all physics K/s TTDIA
216
 Temperature tendency by all radiation K/s TTRAD
217
 Temperature tendency by non-radiation physics K/s TTPHY
218
 precip.index(0.0-1.00) (see note) fraction PREIX
219
 Std. dev. of IR T over 1x1 deg area K TSD1D
220
 Natural log of surface pressure ln(kPa) NLGSP
221
 Planetary boundary layer height m HPBL
222
 5-wave geopotential height gpm 5WAVH
223
 Plant canopy surface water kg/m2 CNWAT
224
 Soil type (as in Zobler) Integer (0-9) SOTYP
225
 Vegitation type (as in SiB) Integer (0-13) VGTYP
226
 Blackadar's mixing length scale m BMIXL
227
 Asymptotic mixing length scale m AMIXL
228
 Potential evaporation kg/m2 PEVAP
229
 Snow phase-change heat flux W/m2 SNOHF
230
 5-wave geopotential height anomaly gpm 5WAVA
231
 Convective cloud mass flux Pa/s MFLUX
232
 Downward total radiation flux W/m2 DTRF
233
 Upward total radiation flux W/m2 UTRF
234
 Baseflow-groundwater runoff kg/m2 BGRUN
235
 Storm surface runoff kg/m2 SSRUN
236
 Supercooled Large Droplet (SLD) Icing Potential Diagnostic non-dim SIPD
237
 Total ozone Kg/m2 03TOT
238
 Snow cover percent SNOWC
239
 Snow temperature K SNO T
240
 Covariance between temperature
and vertical component of the wind.
Defined as [wT]-[w][T], where
"[]" indicates the mean over the
indicated time span		 K*m/s COVTW
241
 Large scale condensat. heat rate K/s LRGHR
242
 Deep convective heating rate K/s CNVHR
243
 Deep convective moistening rate kg/kg/s CNVMR
244
 Shallow convective heating rate K/s SHAHR
245
 Shallow convective moistening rate kg/kg/s SHAMR
246
 Vertical diffusion heating rate K/s VDFHR
247
 Vertical diffusion zonal acceleration m/s2 VDFUA
248
 Vertical diffusion meridional accel m/s2 VDFVA
249
 Vertical diffusion moistening rate kg/kg/s VDFMR
250
 Solar radiative heating rate K/s SWHR
251
 long wave radiative heating rate K/s LWHR
252
 Drag coefficient non-dim CD
253
 Friction velocity m/s FRICV
254
 Richardson number non-dim. RI

F. Level or Layer

Octet 10 Type of level/layer Octet 11 - Value 1 Octet 12 - Value 2
0 reserved
1 surface of earth including sea surface
2 cloud base
3 cloud top
4 freezing level (0C)
5 adiabatic condensation level
6 maximum wind level
7 tropopause level
8 nominal top of atmosphere
9 sea bottom
10-99 reserved  
100 isobaric level pressure in hectoPascals (hPa)
101 layer between two isobaric levels pressure of top (kPa) pressure of bottom (kPa)
102 mean sea level 0 0
103 fixed height level above mean sea level (MSL) height in meters
104 layer between two height levels above MSL height of top (hm) height of bottom (hm)
105 fixed height above ground level height in meters
106 layer between two height levels above ground height of top (hm) height of bottom (hm)
107 sigma level sigma value in 1/10000
108 layer between two sigma levels value at top in 1/100 value at bottom in 1/100
109 hybrid level level number
110 layer between two hybrid levels level number of top level number of bottom
111 depth below surface centimeters
112 layer between two levels below surface depth of top (cm) depth of bottom (cm)
113 isentropic level potential temperature (K)
114 layer between two isentropic levels 475-theta of top (K) 475-theta of bottom (K)
115 level at pressure difference above ground pressure difference (hPa)
116 layer between two levels at pressure difference above ground pressure difference of top (hPa) pressure difference of bottom (hPa)
117 potential vorticity surface pv value in units of 10-6Km2/kgs
119 Eta level Eta value in 1/10000
120 layer between two Eta levels Eta value at top in 1/100 Eta value at bottom in 1/100
121 layer between two pressure levels 1100-pressure of top (hPA) 1100-pressure of bottom (hPa)
125 height level height (cm)
126 isobaric level pressure (Pa)
128 layer between two sigma levels 1.1-sigma of top in 1/1000 1.1-sigma of bottom in 1/1000
141 layer between two pressure levels pressure of top (kPa) 1100-pressure of bottom (hPa)
160 depth below sea level depth (m)
200 entire atmosphere
201 entire ocean

G. Forecast Time Units

Value Time Unit
0 minute
1 hour
2 day
3 month
4 year
5 decade
6 normal (30 years)
7 century
8-253 reserved
254 second

H. Time Range Indicator

Value Meaning
00 Forecast product valid at reference time + P1 P1>0), or uninitialized analysis product for reference time (P1=0) or image product for reference time (P1=0)
01 Initialized analysis product for reference time (P1=0).
02 Product with a valid time ranging between reference time + P1 and reference time + P2
03 Average (reference time + P1 to reference time + P2)
04 Accumulation (reference time + P1 to reference time + P2). Product considered valid at reference time + P2
05 Difference(reference time + P2 minus reference time + P1) product considered valid at reference time + P2
06-09 reserved
10 P1 occupies octets 19 and 20; product valid at reference time + P1
11-50 reserved
51 Climatological Mean Value: multiple year averages of quantities which are themselves means over some period of time (P2) less than a year. The reference time (R) indicates the date and time of the start of a period of time, given by R to R + P2, over which a mean is formed; N indicates the number of such period-means that are averaged together to form the climatological value, assuming that the N period-mean fields are separated by one year. The reference time indicates the start of the N-year climatology. N is given in octets 22-23 of the PDS.
If P1 = 0 then the data averaged in the basic interval P2 are assumed to be continuous, i.e., all available data are simply averaged together.
If P1 = 1 (the units of time - octet 18, code table 4 - are not relevant here) then the data averaged together in the basic interval P2 are valid only at the time (hour, minute) given in the reference time, for all the days included in the P2 period. The units of P2 are given by the contents of octet 18 and Table 4.
52-112 reserved
113 Average of N forecasts (or initialized analyses); each product has forecast period of P1 (P1=0 for initialized analyses); products have reference times at intervals of P2, beginning at the given reference time.
114 Accumulation of N forecasts (or initialized analyses); each product has forecast period of P1 (P1=0 for initialized analyses); products have reference times at intervals of P2, beginning at the given reference time.
115 Average of N forecasts, all with the same reference time; the first has a forecast period of P1, the remaining forecasts follow at intervals of P2.
116 Accumulation of N forecasts, all with the same reference time; the first has a forecast period of P1, the remaining follow at intervals of P2.
117 Average of N forecasts, the first has a period of P1, the subsequent ones have forecast periods reduced from the previous one by an interval of P2; the reference time for the first is given in octets 13-17, the subsequent ones have reference times increased from the previous one by an interval of P2. Thus all the forecasts have the same valid time, given by the initial reference time + P1.
118 Temporal variance, or covariance, of N initialized analyses; each product has forecast period P1=0; products have reference times at intervals of P2, beginning at the given reference time.
119 -122 reserved
123 Average of N uninitialized analyses, starting at the reference time, at intervals of P2.
124 Accumulation of N uninitialized analyses, starting at the reference time, at intervals of P2.
125-254 reserved

I. Data Representation Type

Value Meaning
00 Latitude/Longitude Grid also called Equidistant Cylindrical or Plate Carree projection grid
01 Mercator Projection Grid
02 Gnomonic Projection Grid
03 Lambert Conformal, secant or tangent, conical or bipolar (normal or oblique) Projection Grid
04 Gaussian Latitude/Longitude Grid
05 Polar Stereographic Projection Grid
06-12 reserved - see Manual on Codes
13 Oblique Lambert conformal, secant or tangent, conical or bipolar, projection
14 - 49 reserved - see Manual on Codes
50 Spherical Harmonic Coefficients
51 - 89 reserved - see Manual on Codes
90 Space view perspective or orthographic grid
91 - 254 reserved - see Manual on Codes

J. Resolution and Component Flags

Bit Value Meaning
1 0 Direction increments not given
  1 Direction increments given
2 0 Earth assumed spherical with radius = 6367.47 km
  1 Earth assumed oblate spheroid with size as determined by IAU in 1965: 6378.160 km, 6356.775 km, f = 1/297.0
3-4   reserved (set to 0)
5 0 u- and v-components of vector quantities resolved relative to easterly and northerly directions
  1 u and v components of vector quantities resolved relative to the defined grid in the direction of increasing x and y (or i and j) coordinates respectively
6-8   reserved (set to 0)

Note: If the GDS is not included in a message then any wind components are assumed to be resolved relative to the grid specified in the PDS with u and v defined as positive in the direction of increasing x and y (or i and j) coordinates respectively.

K. Scanning Mode Flag

Bit Value Meaning
1 0 Points scan in +i direction
  1 Points scan in -i direction
2 0 Points scan in -j direction
  1 Points scan in +j direction
3 0 Adjacent points in i direction are consecutive (FORTRAN: (I,J))
  1 Adjacent points in j direction are consecutive (FORTRAN: (J,I))

Note: i direction is defined as west to east along a parallel of latitude, or left to right along an x axis. j direction is defined as south to north along a meridian of longitude, or bottom to top along a y axis.

L. BDS Flag

Bit Value Meaning
1 0 Grid point data
  1 Spherical Harmonic Coefficients
2 0 Simple packing
  1 Second order ("Complex") Packing
3 0 Original data were floating point values
  1 Original data were integer values
4 0 No additional flags at octet 14
  1 Octet 14 contains flag bits 5 - 12

The following gives the meaning of the bits in octet 14 ONLY if bit 4 is set to 1. Otherwise octet 14 contains regular binary data.

5   Reserved (set to 0)
6 0 Single datum at each grid point
  1 Matrix of values at each grid point
7 0 No secondary bit maps
  1 Secondary bit maps present
8 0 Second order values have constant width
  1 Second order values have different widths
9-12   Reserved (set to 0)

Notes:

  1. Bit 3 is set to 1 to indicate that the original data were integers; when this is the case any non-zero reference values should be rounded to an integer value prior to placing in the GRIB BDS.
  2. Bit 4 is set to 1 to indicate that bits 5 to 12 are contained in octet 14 of the data section.
  3. Although GRIB is not capable of representing a matrix of data values at each grid point, the meaning of bit 6 is retained in anticipation of a future capability.
  4. When secondary bit maps are present in the data (used in association with second order packing) this is indicated by setting bit 7 to 1.
  5. When octet 14 contains the extended flag information, octets 12 and 13 will also contain "special" information; the actual data will begin in a subsequent octet. See above.

Updated Mar 2021

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