Local definition 4: Ocean model data

Local definitions

Octets Key Type Contents
41 localDefinitionNumber unsigned ECMWF local GRIB use definition identifier. 4 = Ocean model data.
42 class codetable Class
43 type codetable Type
44-45 stream codetable Stream
46-49 experimentVersionNumber ksec1expver Version number or experiment identifier. (4 ASCII characters, right justified)
50-51, if stream = 109; 050, otherwise perturbationNumber unsigned Ensemble member number
51, unless stream = 1090 Zero
52 flagShowingPostAuxiliaryArrayInUse unsigned 1 (a flag showing a post-auxiliary array is in use)
53 systemNumber unsigned System number
54 methodNumber unsigned Method number
55 spaceUnitFlag unsigned Space unit flag (applies only if lengths not otherwise labelled): 0 = metres i<128 = 10**i metres i>128 = 10**(i-256) metres
56 verticalCoordinateDefinition unsigned Vertical coordinate definition (z): 0 = z above origin 1 = R from origin 2 = h above mean sea level geopotential 3 = h above ground surface 160 = Geopotential depth below mean sea level (mm) 161 = Ocean isopycnic surface (potential density)
57 horizontalCoordinateDefinition unsigned Horizontal coordinate definition (x,y): 0 = Latitude/longitude (microdegrees) 1 = Cartesian (fundamental origin) 2 = Cartesian (shifted, rotated origin) (+info) 3 = Regular gaussian grid (microdegrees) (+info) 4 = Polar stereographic (+info) 5 = Spherical harmonic coefficients (INTEGERs) (+info)
58 timeUnitFlag unsigned Time unit flag: 0 = Seconds 1 = Minutes 2 = Hours 3 = Days 4 = Years 5128 = 10**(i-256) seconds
59 timeCoordinateDefinition unsigned Time coordinate definition (t): 0 = Real Earth time (UTC) 1 = Ideal Earth time (360 * 86400s days per year)
60 mixedCoordinateFieldFlag unsigned Mixed coordinate field flag: 0 = No mixed coordinates 1 = x,y coordinates mixed (+info) 2 = x,z coordinates mixed (+info) 3 = y,z coordinates mixed (+info) 4 = x,t coordinates mixed (+info) 5 = y,t coordinates mixed (+info) 6 = z,t coordinates mixed (+info)
61 coordinate1Flag unsigned Coordinate 1 flag (usually time).
62 averaging1Flag unsigned Averaging flag: 0 = no averaging (data on/at level 1) 1 = inclusive average between level 1 and 2 2 = exclusive average between level 1 and 2
63-66 coordinate1Start signed Position of level 1
67-70 coordinate1End signed Position of level 2 (or zero if not used)
71 coordinate2Flag unsigned Coordinate 2 flag (usually z-coordinate).
72 averaging2Flag unsigned Averaging flag: 0 = no averaging (data on/at level 1) 1 = inclusive average between level 1 and 2 2 = exclusive average between level 1 and 2
73-76 coordinate2Start signed Position of level 1
77-80 coordinate2End signed Position of level 2 (or zero if not used)
81 coordinate3Flag unsigned Coordinate 3 flag (x-axis, usually longitude).
82 coordinate4Flag unsigned Coordinate 4 flag (y-axis, usually latitude).
83-86 coordinate4OfFirstGridPoint signed Coordinate 4 of first grid point
87-90 coordinate3OfFirstGridPoint signed Coordinate 3 of first grid point
91-94 coordinate4OfLastGridPoint signed Coordinate 4 of last grid point
95-98 coordinate3OfLastGridPoint signed Coordinate 3 of last grid point
99-102 iIncrement signed i-increment
103-106 jIncrement signed j-increment
107 flagForIrregularGridCoordinateList codeflag Flag for irregular grid coordinate list: 0 = none 1 = x-axis values (typically longitude) 2 = y-axis values (typically latitude) 3 = first x-axis, then y-axis values given
108 flagForNormalOrStaggeredGrid codeflag Flag for normal or staggered grid: 0 = normal grid (all rows have same x-coordinate system) 1 = staggered grid (odd and even rows have different x-coordinate systems, eg Arakawa grid).
109 flagForAnyFurtherInformation codeflag Flag for any further information: 0 = none 1 = auxiliary array contains x-axis topographic depths/heights.
110 numberInHorizontalCoordinates unsigned Number of entries in the horizontal coordinate definition
111-112 numberInMixedCoordinateDefinition unsigned Number of entries in mixed coordinate definition
113-114 numberInTheGridCoordinateList unsigned Number of entries in the grid coordinate list
115-116 numberInTheAuxiliaryArray unsigned Number of entries in the auxiliary array
A1-nn horizontalCoordinateSupplement unsigned Horizontal coordinate definition
B1-nn mixedCoordinateDefinition unsigned Mixed coordinate definition
C1-nn gridCoordinate unsigned Grid coordinate list
D1-nn auxiliary unsigned Auxiliary array
E1-nn postAuxiliary unsigned Post-auxiliary array
Notes:

( 1) The time and time-range data should be set in the main section, if possible.

( 2) The indicator of type of level should be set to 160 (depth below sea level) for all oceanographic data. The depth in metres should be set to the appropriate value if the field is a horizontal section, and to zero in all other cases.

( 3) It is assumed that the grid description section of the GRIB code corresponds to a latitude/longitude grid, with correct values for the number of points along parallels/meridians, and the coordinates of the first and last data points are in millidegrees (or the appropriate units from this section, divided by 1000).

( 4) The coordinate increments should be given to the extent that the field is regular.