GRIB Format
Edition 1
1. GRIB Overview
The GRIB product is broken down into several subsections:
 Indicator Section
 Product Definition Section (PDS)
 Grid Description Section (GDS)  optional
 Bit Map Section (BMS)  optional
 Binary Data Section (BDS)
 End Section
Tables:
 Originating Centers
 Process/Model ID
 Grid Indentifiers
 GDS/BMS Flag
 Parameter and Units
 Level or Layer
 Forecast Time Units
 Time Range Indicator
 Data Representation Type
 Resolution and Component Flags
 Scanning Mode Flag
 BDS Flag
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:
 X = internal value saved in the binary data section. The values depend on the number of bits per grid value.
 D = decimal scale factor
 E = binary scale factor (sign bit plus 15 bit integer)
 R = reference value
Each gridpoint value (Y) is determined from the following formula:
Y * 10^{D} = R + (X * 2^{E})
The reference value (R) uses IBM single precision floating point format.
sAAAAAAA BBBBBBBB BBBBBBBB BBBBBBBB
 s = sign bit, encoded as 0 means positive, 1 means negative
 A...A = 7bit binary integer representing the exponent/characteristic
 B...B = 24bit binary integer, the mantissa.
The appropriate formula to recover the value of R is:
R = (1)^{s} * 2^{(24)} * B * 16^{(A64)}
2. Indicator Section
Byte/Octet  Description 

0104  "GRIB"  ASCII characters to flag data as GRIB data 
0507  Total number of bytes for all data 
08  GRIB edition  currently 1 
2. Product Definition Section (PDS)
Octet/Byte  Description 

0103  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 
1112  Level or Layer values 
13  Initial or Reference Time (octet 1317)  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 
2223  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 subcenter 
2728  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). 
2940  Reserved (need not be present) 
41nnn  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 "subcenter" 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 C1). 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 subcenter 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 subcenter 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, subcenter 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 NCOdefined 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 

0103  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 
0732  Grid description, according to data representation type, except Lambert, Mercator or Space View. 
0742  Grid description for Lambert or Mercator grid 
0744  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 quasiregular 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 "quasiregular" 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 

0708  Ni  No. of points along a latitude circle 
0910  Nj  No. of points along a longitude meridian 
1113  La_{1}  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 
1416  Lo_{1}  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 
1820  La_{2}  Latitude of last grid point (same units, value range, and bit 1 as La_{1}) 
2123  Lo_{2}  Longitude of last grid point (same units, value range, and bit 1 as Lo_{1}) 
2425  Di  Longitudinal Direction Increment (same units as Lo_{1}) (if not given, all bits set = 1) 
26  27  Regular Lat/Lon Grid: Dj  Latitudinal Direction Increment (same units as La_{1}) (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:
 The latitude and longitude of the first and last grid points should always be given, for regular grids.
 If a quasiregular grid is to be described, in which all the rows or columns do not necessarily have the same number of grid points, either Ni (octets 78) or Nj (octets 910) and the corresponding Di (octets 2425) or Dj (octets 2627) shall be coded with all bits set to 1 (missing).
 A quasiregular grid can be defined only for rows or columns, but not both simultaneously. The first point in each row (column) shall be positioned at the meridian (parallel) indicated in octets 1116. The grid points shall be evenly spaced in latitude (longitude).
 For Gaussian grids only the rows can be rendered quasiregular; the first point shall be located at the meridian given in octets 1416 and the last point at the meridian given in octets 2123.
3.2 Grid Definition for Polar Stereographic Grids
Octet  Description 

0708  Nx  Number of points along xaxis 
0910  Ny  Number of points along yaxis 
1113  La1  Latitude of first grid point 
1416  Lo1  Longitude of first grid point 
17  Resolution and component flags 
1820  Lov  The orientation of the grid; i.e., the east longitude value of the meridian which is parallel to the yaxis (or columns of the grid) along which latitude increases as the ycoordinate increases. (Note: The orientation longitude may, or may not, appear within a particular grid.) 
2123  Dx  the Xdirection grid length (see note 2) 
2426  Dy  the Ydirection grid length (see note 2) 
27  Projection center flag (see note 5) 
28  Scanning mode 
29  32  Set to 0 (reserved) 
Notes:
 Latitude and longitude are in millidegrees (thousandths)
 Grid lengths are in units of meters, at the 60 degree latitude circle nearest to the pole in the projection plane.
 Latitude values are limited to the range 0  90,000. Bit 1 is set to 1 to indicate south latitude.
 Longitude values are limited to the range 0  360,000. Bit one is set to 1 to indicate west longitude.
 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.
 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.
 The resolution flag (bit 1 of Table 7) is not applicable.
3.3 Grid Definition for Lambert Conformal, Conic Grids
Octet  Description 

0708  Nx  Number of points along xaxis 
0910  Ny  Number of points along yaxis 
1113  La1  Latitude of first grid point 
1416  Lo1  Longitude of first grid point 
17  Resolution and component flags 
1820  Lov  The orientation of the grid; i.e., the east longitude value of the meridian which is parallel to the yaxis (or columns of the grid) along which latitude increases as the ycoordinate increases. (Note: The orientation longitude may, or may not, appear within a particular grid.) 
2123  Dx  the Xdirection grid length (see note 2) 
2426  Dy  the Ydirection grid length (see note 2) 
27  Projection center flag (see note 5) 
28  Scanning mode 
2931  Latin 1  The first latitude from the pole at which the secant cone cuts the spherical earth. (See Note 8) 
3234  Latin 2  The second latitude from the pole at which the secant cone cuts the spherical earth. (See Note 8) 
3537  Latitude of southern pole (millidegrees) 
3840  Longitude of southern pole (millidegrees) 
4142  Reserved (set to 0) 
Notes:
 Latitude and longitude are in millidegrees (thousandths)
 Grid lengths are in units of meters, at the intersection latitude circle nearest to the pole in the projection plane.
 Latitude values are limited to the range 0  90,000. Bit 1 is set to 1 to indicate south latitude.
 Longitude values are limited to the range 0  360,000. Bit one is set to 1 to indicate west longitude.
 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  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.
 The resolution flag (bit 1 of Table 7) is not applicable.
 If Latin 1 = Latin 2 then the projection is on a tangent cone.
3.4 Grid Definition for Mercator Grids
Octet  Description 

0708  Ni  Number of points along a latitude circle 
0910  Nj  Number of points along a longitude meridian 
1113  La1  Latitude of first grid point 
1416  Lo1  Longitude of first grid point 
17  Resolution and component flags 
1820  La2  latitude of last grid point 
2123  Lo2  longitude of last grid point 
2426  Latin  The latitude(s) at which the Mercator projection cylinder intersects the earth. 
27  Reserved (set to 0) 
28  Scanning mode 
2931  Di  the longitudinal direction increment (see Note 2) 
3234  Dj  the latitudinal direction increment (see note 2) 
3542  Reserved (set to 0) 
Notes:
 Latitude and longitude are in millidegrees (thousandths)
 Grid lengths are in units of meters, at the circle of latitude specified by Latin.
 Latitude values are limited to the range 0  90,000. Bit 1 is set to 1 to indicate south latitude.
 Longitude values are limited to the range 0  360,000. Bit one is set to 1 to indicate west longitude.
 The latitude and longitude of the last grid point should always be given.
 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 

0708  Nx  number of points along x axis (columns) 
0910  Ny  number of points along y axis (rows or lines) 
1113  Lap  latitude of subsatellite point 
1416  Lop  longitude of subsatellite point 
17  Resolution and component flags (Table 7) 
1820  dx  apparent diameter of earth in grid lengths, in x direction 
2123  dy  apparent diameter of earth in grid lengths, in y direction 
2425  Xp  Xcoordinate of sub satellite point 
2627  Yp  Ycoordinate of subsatellite point 
28  Scanning Mode (Table 8) 
2931  the orientation of the grid; i.e., the angle in millidegrees between the increasing y axis and the meridian of the subsatellite point in the direction of increasing latitude (see Note 3). 
3234  Nr  the altitude of the camera from the earth's center, measured in units of the earth's (equatorial) radius (See Note 4). 
3544  reserved 
Notes:
 It is assumed that the satellite is at its nominal position, i.e., it is looking directly at its subsatellite point.
 Octet 3234 shall be set to all ones (missing) to indicate the orthographic view (from infinite distance).
 It is the angle between increasing y axis and the meridian 180 degrees east if the subsatellite point is the North pole; or the meridian 0 degrees, if the subsatellite point is the south pole.
 The apparent angular size of the earth will be given by 2 x asin(1/Nr).
 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 

0103  Length in bytes of BMS 
04  Number of unused bits at end of Section 3. 
0506  Numeric: if 0: a bit map follows; otherwise: the numeric refers to a predefined bit map provided by the center 
07nnn  Bit map, zero filled to an even number of octets 
5. Binary Data Section (BDS)
This section contains the packed binary data.
Octet  Description 

0103  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. 
0506  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). 
0710  Reference value (minimum value); floating point representation of the number. 
11  Number of bits into which a datum point is packed 
12nnn  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 

14  "7777" 
Table A. Originating Centers (PDS)
Value  Center 


Melbourne (WMC) 

Melbourne (WMC) 

Moscow (WMC) 

Moscow (WMC) 

US National Weather Service  NCEP (WMC) 

US National Weather Service  NWSTG (WMC) 

US National Weather Service  Other (WMC) 

Cairo (RSMC/RAFC) 

Dakar (RSMC/RAFC) 

Nairobi (RSMC/RAFC) 

Atananarivo (RSMC) 

TunisCasablanca (RSMC) 

Las Palmas (RAFC) 

Algiers (RSMC) 

Lagos (RSMC) 

Khabarovsk (RSMC) 

New Delhi (RSMC/RAFC) 

Novosibirsk (RSMC) 

Tashkent (RSMC) 

Jeddah (RSMC) 

Japanese Meteorological Agency  Tokyo (RSMC) 

Bankok 

Ulan Bator 

Beijing (RSMC) 

Seoul 

Buenos Aires (RSMC/RAFC) 

Brasilia (RSMC/RAFC) 

Santiago 

Brasilian Space Agency  INPE 

Miami (RSMC/RAFC) 

National Hurricane Center, Miami 

Canadian Meteorological Service  Montreal (RSMC) 

Canadian Meteorological Service  Montreal (RSMC) 

San Francisco 

U.S. Air Force  Global Weather Center 

US Navy  Fleet Numerical Oceanography Center 

NOAA Forecast Systems Lab, Boulder CO 

National Center for Atmospheric Research (NCAR), Boulder, CO 

Honolulu 

Darwin (RSMC) 

Melbourne (RSMC) 

Wellington (RSMC/RAFC) 

U.K. Met Office  Bracknell 

Moscow (RSMC/RAFC) 

Offenbach (RSMC) 

Rome (RSMC) 

Norrkoping 

French Weather Service  Toulouse 

Helsinki 

Belgrade 

Oslo 

Prague 

Episkopi 

Ankara 

Frankfurt/Main (RAFC) 

London (WAFC) 

Copenhagen 

Rota 

Athens 

European Space Agency (ESA) 

European Center for MediumRange Weather Forecasts  Reading 

DeBilt, Netherlands 
B. Process/Model ID
NCEP values:
Value  Model 


Ultra Violet Index Model 

NCEP/ARL Transport and Dispersion Model1 

Satellite Derived Precipitation and temperatures, from IR (See PDS Octet 41... for specific satellite ID) 

Global WindWave Forecast Model 

Limitedarea Fine Mesh (LFM) analysis 

Snow Cover Analysis 

Forecaster generated field 

Value added post processed field 

Nested Grid forecast Model (NGM) 

Global Optimum Interpolation Analysis (GOI) from "Aviation" run 

Global Optimum Interpolation Analysis (GOI) from "Final" run 

Sea Surface Temperature Analysis 

Coastal Ocean Circulation Model 

Ozone Analysis from TIROS Observations 

Ozone Analysis from Nimbus 7 Observations 

LFMFourth Order Forecast Model 

Regional Optimum Interpolation Analysis (ROI) 

80 wave triangular, 18layer Spectral model from "Aviation" run 

80 wave triangular, 18 layer Spectral model from "Medium Range Forecast" run 

QuasiLagrangian Hurricane Model (QLM) 

Fog Forecast model  Ocean Prod. Center 

Gulf of Mexico Wind/Wave 

Gulf of Alaska Wind/Wave 

Bias corrected Medium Range Forecast 

126 wave triangular, 28 layer Spectral model from "Aviation" run 

126 wave triangular, 28 layer Spectral model from "Medium Range Forecast" run 

Backup from the previous run 

62 wave triangular, 28 layer Spectral model from "Medium Range Forecast" run 

Spectral Statistical Interpolation (SSI) analysis from "Aviation" run. 

Spectral Statistical Interpolation (SSI) analysis from "Final" run. 

No longer used 

MESO ETA Model (currently 12 km) 

No longer used 

RUC Model, from Forecast Systems Lab (isentropic; scale: 60km at 40N) 

CAC Ensemble Forecasts from Spectral (ENSMB) 

NOAA Wave Watch III (NWW3) Ocean Wave Model 

Nonhydrostatic Meso Model (NMM) Currently 8 km) 

62 wave triangular, 28 layer spectral model extension of the "Medium Range Forecast" run 

62 wave triangular, 28 layer spectral model extension of the "Aviation" run 

62 wave triangular, 28 layer spectral model run from the "Medium Range Forecast" final analysis 

62 wave triangular, 28 layer spectral model run from the T62 GDAS analysis of the "Medium Range Forecast" run 

T170/L42 Global Spectral Model from MRF run 

T126/L42 Global Spectral Model from MRF run 

Global Forecast System Model (formerly known as the Aviation) T254  Forecast hours 0084 T170  Forecast hours 87180 T126  Forecast hours 192  384 

RUC Surface Analysis (scale: 60km at 40N) 

RUC Surface Analysis (scale: 40km at 40N) 

RUC Model from FSL (isentropic; scale: 20km at 40N) 

ETA Model  15km version 

Ice Concentration Analysis 

Western North Atlantic Regional Wave Model 

Alaska Waters Regional Wave Model 

North Atlantic Hurricane Wave Model 

Eastern North Pacific Regional Wave Model 

North Pacific Hurricane Wave Model 

Sea Ice Forecast Model 

Lake Ice Forecast Model 

Global Ocean Forecast Model 

Merge of fields from the RUC, Eta, and Spectral Model 

North American Regional Reanalysis (NARR) 

Land Data Assimilation and Forecast System 

NWS River Forecast System (NWSRFS) 

NWS Flash Flood Guidance System (NWSFFGS) 

WSR88D Stage II Precipitation Analysis 

WSR88D Stage III Precipitation Analysis 

Quantitative Precipitation Forecast generated by NCEP 

River Forecast Center Quantitative Precipitation Forecast mosaic generated by NCEP 

River Forecast Center Quantitative Precipitation estimate mosaic generated by NCEP 

NDFD product generated by NCEP/HPC 

National Convective Weather Diagnostic generated by NCEP/AWC 

Current Icing Potential automated product genterated by NCEP/AWC 

CPC Manual Forecast Product 

EPA Air Quality Forecast 
C. Grid Indentifiers
International Exchange Grids
Value 
Resolution 
Area 
Grid Shape 
Gridpoints 


21 
5.0 x 2.5 
0180E, 090N 
37 
36 + pole 
1333 
22 
5.0 x 2.5 
180W0, 090N 
37 
36 + pole 
1333 
23 
5.0 x 2.5 
0180E, 90S0 
pole + 37 
36 
1333 
24 
5.0 x 2.5 
180W0, 90S0 
pole + 37 
36 
1333 
25 
5.0 x 5.0 
0355E, 090N 
72 
18 + pole 
1297 
26 
5.0 x 5.0 
0355E, 90S0 
pole + 72 
18 
1297 
61 
2.0 x 2.0 
0180E, 090N 
91 
45 + pole 
4096 
62 
2.0 x 2.0 
180W0, 090N 
91 
45 + pole 
4096 
63 
2.0 x 2.0 
0180E, 90S0 
pole + 91 
45 
4096 
64 
2.0 x 2.0 
180W0, 90S0 
pole + 91 
45 
4096 
255 
(nonstandard 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  
38  0  reserved 
E. Parameter and Units
Value  Parameter  Units  Abbrev. 


Reserved  


Pressure  Pa  PRES 

Pressure reduced to MSL  Pa  PRMSL 

Pressure tendency  Pa/s  PTEND 

Potential vorticity  Km^{2/}kg/s  PVORT 

ICAO Standard Atmosphere Reference Height  m  ICAHT 

Geopotential  m^{2}/s^{2}  GP 

Geopotential height  gpm  HGT 

Geometric height  m  DIST 

Standard deviation of height  m  HSTDV 

Total ozone  Dobson  TOZNE 

Temperature  K  TMP 

Virtual temperature  K  VTMP 

Potential temperature  K  POT 

Pseudoadiabatic potential temperature or equivalent potential temperature 
K  EPOT 

Maximum temperature  K  T MAX 

Minimum temperature  K  T MIN 

Dew point temperature  K  DPT 

Dew point depression (or deficit)  K  DEPR 

Lapse rate  K/m  LAPR 

Visibility  m  VIS 

Radar Spectra (1)  
RDSP1 

Radar Spectra (2)  
RDSP2 

Radar Spectra (3)  
RDSP3 

Parcel lifted index (to 500 hPa)  K  PLI 

Temperature anomaly  K  TMP A 

Pressure anomaly  Pa  PRESA 

Geopotential height anomaly  gpm  GP A 

Wave Spectra (1)  
WVSP1 

Wave Spectra (2)  
WVSP2 

Wave Spectra (3)  
WVSP3 

Wind direction (from which blowing)  deg true  WDIR 

Wind speed  m/s  WIND 

ucomponent of wind  m/s  U GRD 

vcomponent of wind  m/s  V GRD 

Stream function  m^{2}/s  STRM 

Velocity potential  m^{2}/s  V POT 

Montgomery stream function  m^{2}/s^{2}  MNTSF 

Sigma coordinate vertical velocity  /s  SGCVV 

Vertical velocity (pressure)  Pa/s  V VEL 

Vertical velocity (geometric)  m/s  DZDT 

Absolute vorticity  /s  ABS V 

Absolute divergence  /s  ABS D 

Relative vorticity  /s  REL V 

Relative divergence  /s  REL D 

Vertical ucomponent shear  /s  VUCSH 

Vertical vcomponent shear  /s  VVCSH 

Direction of current  Degree true  DIR C 

Speed of current  m/s  SP C 

ucomponent of current  m/s  UOGRD 

vcomponent of current  m/s  VOGRD 

Specific humidity  kg/kg  SPF H 

Relative humidity  %  R H 

Humidity mixing ratio  kg/kg  MIXR 

Precipitable water  kg/m^{2}  P WAT 

Vapor pressure  Pa  VAPP 

Saturation deficit  Pa  SAT D 

Evaporation  kg/m^{2}  EVP 

Cloud Ice  kg/m^{2}  C ICE 

Precipitation rate  kg/m^{2}/s  PRATE 

Thunderstorm probability  %  TSTM 

Total precipitation  kg/m^{2}  A PCP 

Large scale precipitation (nonconv.)  kg/m^{2}  NCPCP 

Convective precipitation  kg/m^{2}  ACPCP 

Snowfall rate water equivalent  kg/m^{2}/s  SRWEQ 

Water equiv. of accum. snow depth  kg/m^{2}  WEASD 

Snow depth  m  SNO D 

Mixed layer depth  m  MIXHT 

Transient thermocline depth  m  TTHDP 

Main thermocline depth  m  MTHD 

Main thermocline anomaly  m  MTH A 

Total cloud cover  %  T CDC 

Convective cloud cover  %  CDCON 

Low cloud cover  %  L CDC 

Medium cloud cover  %  M CDC 

High cloud cover  %  H CDC 

Cloud water  kg/m^{2}  C WAT 

Best lifted index (to 500 hPa)  K  BLI 

Convective snow  kg/m^{2}  SNO C 

Large scale snow  kg/m^{2}  SNO L 

Water Temperature  K  WTMP 

Land cover (land=1, sea=0) (see note)  proportion  LAND 

Deviation of sea level from mean  m  DSL M 

Surface roughness  m  SFC R 

Albedo  %  ALBDO 

Soil temperature  K  TSOIL 

Soil moisture content  kg/m^{2}  SOIL M 

Vegetation  %  VEG 

Salinity  kg/kg  SALTY 

Density  kg/m^{3}  DEN 

Water runoff  kg/m^{2}  WATR 

Ice cover (ice=1, no ice=0) (See Note)  proportion  ICE C 

Ice thickness  m  ICETK 

Direction of ice drift  deg. true  DICED 

Speed of ice drift  m/s  SICED 

ucomponent of ice drift  m/s  U ICE 

vcomponent of ice drift  m/s  V ICE 

Ice growth rate  m/s  ICE G 

Ice divergence  /s  ICE D 

Snow melt  kg/m^{2}  SNO M 

Significant height of combined wind waves and swell 
m  HTSGW 

Direction of wind waves (from which)  Degree true  WVDIR 

Significant height of wind waves  m  WVHGT 

Mean period of wind waves  s  WVPER 

Direction of swell waves  Degree true  SWDIR 

Significant height of swell waves  m  SWELL 

Mean period of swell waves  s  SWPER 

Primary wave direction  Degree true  DIRPW 

Primary wave mean period  s  PERPW 

Secondary wave direction  Degree true  DIRSW 

Secondary wave mean period  s  PERSW 

Net shortwave radiation flux (surface)  W/m^{2}  NSWRS 

Net long wave radiation flux (surface)  W/m^{2}  NLWRS 

Net shortwave radiation flux (top of atmosphere)  W/m^{2 }  NSWRT 

Net long wave radiation flux (top of atmosphere)  W/m^{2 }  NLWRT 

Long wave radiation flux  W/m^{2 }  LWAVR 

Short wave radiation flux  W/m^{2 }  SWAVR 

Global radiation flux  W/m^{2 }  G RAD 

Brightness temperature  K  BRTMP 

Radiance (with respect to wave number)  W/m/sr  LWRAD 

Radiance (with respect to wave length)  W/m^{3}/sr  SWRAD 

Latent heat net flux  W/m^{2 }  LHTFL 

Sensible heat net flux  W/m^{2 }  SHTFL 

Boundary layer dissipation  W/m^{2 }  BLYDP 

Momentum flux, u component  N/m^{2 }  U FLX 

Momentum flux, v component  N/m^{2 }  V FLX 

Wind mixing energy  J  WMIXE 

Image data 

IMG D 

Reserved for use by originating center 


NCEP usage:
Value  Parameter  Units  Abbrev. 


Mean Sea Level Pressure (Standard Atmosphere Reduction) 
Pa  MSLSA 

Mean Sea Level Pressure (MAPS System Reduction) 
Pa  MSLMA 

Mean Sea Level Pressure (Eta Model Reduction) 
Pa  MSLET 

Surface lifted index  K  LFT X 

Best (4 layer) lifted index  K  4LFTX 

K index  K  K X 

Sweat index  K  S X 

Horizontal moisture divergence  kg/kg/s  MCONV 

Vertical speed shear  1/s  VW SH 

3hr pressure tendency Std. Atmos. Reduction 
Pa/s  TSLSA 

BruntVaisala frequency (squared)  1/s^{2}  BVF 2 

Potential vorticity (density weighted)  1/s/m  PV MW 

Categorical rain (yes=1; no=0)  nondim  CRAIN 

Categorical freezing rain (yes=1; no=0)  nondim  CFRZR 

Categorical ice pellets (yes=1; no=0)  nondim  CICEP 

Categorical snow (yes=1; no=0)  nondim  CSNOW 

Volumetric soil moisture content  fraction  SOILW 

Potential evaporation rate  W/m**2  PEVPR 

Cloud workfunction  J/kg  CWORK 

Zonal flux of gravity wave stress  N/m**2  UGWD 

Meridional flux of gravity wave stress  N/m**2  VGWD 

Potential vorticity  m**2/s/kg  PV 

Covariance between meridional and zonal components of the wind. Defined as [uv][u][v], where "[]" indicates the mean over the indicated time span. 
m^{2}/s^{2}  COVMZ 

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 

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 

Cloud water  Kg/kg  CLWMR 

Ozone mixing ratio  Kg/kg  O3MR 

Ground Heat Flux  W/m^{2}  GFLUX 

Convective inhibition  J/kg  CIN 

Convective Available Potential Energy  J/kg  CAPE 

Turbulent Kinetic Energy  J/kg  TKE 

Condensation pressure of parcel lifted from indicated surface 
Pa  CONDP 

Clear Sky Upward Solar Flux  W/m^{2}  CSUSF 

Clear Sky Downward Solar Flux  W/m^{2}  CSDSF 

Clear Sky upward long wave flux  W/m^{2}  CSULF 

Clear Sky downward long wave flux  W/m^{2}  CSDLF 

Cloud forcing net solar flux  W/m^{2}  CFNSF 

Cloud forcing net long wave flux  W/m^{2}  CFNLF 

Visible beam downward solar flux  W/m^{2}  VBDSF 

Visible diffuse downward solar flux  W/m^{2}  VDDSF 

Near IR beam downward solar flux  W/m^{2}  NBDSF 

Near IR diffuse downward solar flux  W/m^{2}  NDDSF 

Rain water mixing ratio  Kg/Kg  RWMR 

Snow mixing ratio  Kg/Kg  SNMR 

Momentum flux  N/m^{2}  M FLX 

Mass point model surface  nondim  LMH 

Velocity point model surface  nondim  LMV 

Model layer number (from bottom up)  nondim  MLYNO 

latitude (90 to +90)  deg  NLAT 

east longitude (0360)  deg  ELON 

Ice mixing ratio  Kg/Kg  ICMR 

Graupel mixing ratio  Kg/Kg  GRMR 

Surface wind gust  m/s  GUST 

xgradient of log pressure  1/m  LPS X 

ygradient of log pressure  1/m  LPS Y 

xgradient of height  m/m  HGT X 

ygradient of height  m/m  HGT Y 

Turbulence Potential Forecast Index  nondim  TPFI 

Total Icing Potential Diagnostic  nondim  TIPD 

Lightning  nondim  LTNG 

Rate of water dropping from canopy to ground 



Virtual potential temperature  K  VPTMP 

Storm relative helicity  m^{2}/s^{2}  HLCY 

Probability from ensemble  numeric  PROB 

Probability from ensemble normalized with respect to climate expectancy 
numeric  PROBN 

Probability of precipitation  %  POP 

Percent of frozen precipitation  %  CPOFP 

Probability of freezing precipitation  %  CPOZP 

ucomponent of storm motion  m/s  USTM 

vcomponent of storm motion  m/s  VSTM 

Number concentration for ice particles 

NCIP 

Direct evaporation from bare soil  W/m^{2}  EVBS 

Canopy water evaporation  W/m^{2}  EVCW 

Icefree water surface  %  ICWAT 

Convective weather detection index  nondim  CWDI 

VAFTAD 



downward short wave rad. flux  W/m^{2}  DSWRF 

downward long wave rad. flux  W/m^{2}  DLWRF 

Ultra violet index (1 hour integration centered at solar noon) 
J/m^{2}  UVI 

Moisture availability  %  MSTAV 

Exchange coefficient  (kg/m^{3})(m/s)  SFEXC 

No. of mixed layers next to surface  integer  MIXLY 

Transpiration  W/m^{2}  TRANS 

upward short wave rad. flux  W/m^{2}  USWRF 

upward long wave rad. flux  W/m^{2}  ULWRF 

Amount of nonconvective cloud  %  CDLYR 

Convective Precipitation rate  kg/m^{2}/s  CPRAT 

Temperature tendency by all physics  K/s  TTDIA 

Temperature tendency by all radiation  K/s  TTRAD 

Temperature tendency by nonradiation physics  K/s  TTPHY 

precip.index(0.01.00) (see note)  fraction  PREIX 

Std. dev. of IR T over 1x1 deg area  K  TSD1D 

Natural log of surface pressure  ln(kPa)  NLGSP 

Planetary boundary layer height  m  HPBL 

5wave geopotential height  gpm  5WAVH 

Plant canopy surface water  kg/m^{2}  CNWAT 

Soil type (as in Zobler)  Integer (09)  SOTYP 

Vegitation type (as in SiB)  Integer (013)  VGTYP 

Blackadar's mixing length scale  m  BMIXL 

Asymptotic mixing length scale  m  AMIXL 

Potential evaporation  kg/m^{2}  PEVAP 

Snow phasechange heat flux  W/m^{2}  SNOHF 

5wave geopotential height anomaly  gpm  5WAVA 

Convective cloud mass flux  Pa/s  MFLUX 

Downward total radiation flux  W/m^{2}  DTRF 

Upward total radiation flux  W/m^{2}  UTRF 

Baseflowgroundwater runoff  kg/m^{2}  BGRUN 

Storm surface runoff  kg/m^{2}  SSRUN 

Supercooled Large Droplet (SLD) Icing Potential Diagnostic  nondim  SIPD 

Total ozone  Kg/m^{2}  03TOT 

Snow cover  percent  SNOWC 

Snow temperature  K  SNO T 

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 

Large scale condensat. heat rate  K/s  LRGHR 

Deep convective heating rate  K/s  CNVHR 

Deep convective moistening rate  kg/kg/s  CNVMR 

Shallow convective heating rate  K/s  SHAHR 

Shallow convective moistening rate  kg/kg/s  SHAMR 

Vertical diffusion heating rate  K/s  VDFHR 

Vertical diffusion zonal acceleration  m/s^{2}  VDFUA 

Vertical diffusion meridional accel  m/s^{2}  VDFVA 

Vertical diffusion moistening rate  kg/kg/s  VDFMR 

Solar radiative heating rate  K/s  SWHR 

long wave radiative heating rate  K/s  LWHR 

Drag coefficient  nondim  CD 

Friction velocity  m/s  FRICV 

Richardson number  nondim.  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  
1099  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  475theta of top (K)  475theta 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^{6}Km^{2}/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  1100pressure of top (hPA)  1100pressure of bottom (hPa) 
125  height level  height (cm)  
126  isobaric level  pressure (Pa)  
128  layer between two sigma levels  1.1sigma of top in 1/1000  1.1sigma of bottom in 1/1000 
141  layer between two pressure levels  pressure of top (kPa)  1100pressure 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 
8253  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 
0609  reserved 
10  P1 occupies octets 19 and 20; product valid at reference time + P1 
1150  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
periodmeans that are averaged together to form the climatological
value, assuming that the N periodmean fields are separated by one
year. The reference time indicates the start of the Nyear
climatology. N is given in octets 2223 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. 
52112  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 1317, 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. 
125254  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 
0612  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  
34  reserved (set to 0)  
5  0  u and vcomponents 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  
68  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  
912  Reserved (set to 0) 
Notes:
 Bit 3 is set to 1 to indicate that the original data were integers; when this is the case any nonzero reference values should be rounded to an integer value prior to placing in the GRIB BDS.
 Bit 4 is set to 1 to indicate that bits 5 to 12 are contained in octet 14 of the data section.
 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.
 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.
 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