GRIB2 - GRID DEFINITION TEMPLATE 3.32769

Rotate Latitude/Longitude (Arakawa Non-E Staggered grid)

Created 05/11/2010


Octet No. Contents
15 Shape of the Earth (See Code Table 3.2)
16
 Scale Factor of radius of spherical Earth
17-20
 Scale value of radius of spherical Earth
21
 Scale factor of major axis of oblate spheroid Earth
22-25
 Scaled value of major axis of oblate spheroid Earth
26
 Scale factor of minor axis of oblate spheroid Earth
27-30
 Scaled value of minor axis of oblate spheroid Earth
31-34
 Ni—number of points along x-axis
35-38
 Nj—number of points along y-axis
39-42
 Basic angle of the initial production domain (see Note 1)
43-46
 Subdivisions of basic angle used to define extreme longitudes and latitudes, and direction increments (see Note 1)
47-50

La1—latitude of first grid point (see Note 1)        

51-54

Lo1—longitude of first grid point (see Note 1)
55
 Resolution and component flags (see Table 3.3)
56-59

La2—center latitude of grid point (see Note1)     

60-63

Lo2—Center longitude of grid point (see Note 1)
64-67

Di—Longitudinal direction increment (see Note1)     

68-71

Dj —Latitudinal direction increment (see Note1)
72

Scanning mode (flags — see Table 3.4)
73-76

Latitude of grid points (Ni,Nj)(see Note1)     

77-80

Longitude of grid points (Ni,Nj)(see Note1)     



Notes:

1.  Basic angle of the initial production domain and subdivisions of this basic angle are provided to manage cases where the recommended unit of 10-6 degrees is not applicable to describe the extreme longitudes and latitudes, and direction increments. For these last six descriptors, the unit is equal to the ratio of the basic angle and the subdivisions number. For ordinary cases, zero and missing values should be coded, equivalent to respective values of 1 and 106  (10-6  degrees unit).

2.  For data on a quasi-regular grid, in which all the rows or columns do not necessarily have the same number of grid points either Ni (octets 31-34) of Nj (octets 35-38) and the corresponding Di (octets 64-67) or Dj (octets 68-71) shall be coded with all bits set to 1 (missing). The actual number of points along each parallel or meridian shall be coded in the octets immediately following the grid definition template (octets [xx+1]-nn), as described in the description of the grid definition section.

3.  A quasi-regular grid is only defined for appropriate grid scanning modes. Either rows or columns, but not both simultaneously, may have variable numbers of points. The first point in each row (column) shall be positioned at the meridian (parallel) indicted by octets 47-54. The grid points shall be evenly spaced in latitude (longitude).

4.  The rotation of the Latitude/Longitude grid is such that the intersection of the "prime meridian" and the "equator" has been located at the central Latitude and Longitude at the area represented.

5.  For better accuracy, it is recommended that Di/Dj resolution stored in (64-67) and (68-71) not be used. Instead, the user should use the Lat/Lon of corner points to calculate Di/Dj.


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