GRIB2 - GRID DEFINITION TEMPLATE 3.4

Variable Resolution Latitude/Longitude

Created 01/07/2013


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 a parallel     
35-38 Nj—number of points along a meridian
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 Resolution and component flags (see Flag Table 3.3 and Note 2)
48 Scanning mode (flags — see Flag Table 3.4)
49-ii List of Longitudes (see Notes 1 and 3)
(ii+1)-jj List of Latitudes (see Notes 1 and 3)


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. For these 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 resolution flag (bit 3-4 of Flag table 3.3) is not applicable.

3.  The list of Ni longitudes and Nj latitudes shall be coded in the octets immediately following the Grid definition template in octets 49 to ii and octets ii+1 to jj respectively, where ii=48+4Ni and jj=48+4Ni+4j.

4.  A scale value of radius of spherical Earth, or major or minor axis of oblate spheroid Earth is derived from applying appropriate scale factor to the value expressed in meters.


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