GRIB2 - GRID DEFINITION TEMPLATE 3.5

Variable Resolution Rotate 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)
49-52 Latitude of the Southern pole of projection (see Note 4)
53-56 Longitude of the Southern pole of projection (see Note 4)
57-60 Angle of rotation of projection (see Note 4)
61-ii List of Longitude (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 10 (10-6  degrees unit).

2.  Three parameters define a general Latitude/Longitude coordinate system, formed by a general rotation of the sphere. One choice for these parameters is:
    (a)   The geographic latitude in degrees of the Southern pole of the coordinate system, e.g Θp;
    (b)   The geographic longitude in degrees of the Southern pole of the coordinate system, e.g λp;
    (c)   The angle of rotation in degrees about the new polar axis (measured clockwise when looking from the Southern to the Northern pole) of the coordinate system, assuming the new axis to have been obtained by first rotating the sphere through λp degrees about the geographic polar aixs, and then rotating through (90 + Θp) degrees so that the Southern pole moved along the (previously rotated) Greenwich meridian.

3.  For the list of Ni longitudes bounds and Nj latitudes bounds at the end of the section ii=60+4Ni and jj=60+4Ni+4Nj.

4.  Regulations 92.1.6 applies.



Back