GRIB2 - GRID DEFINITION TEMPLATE 3.10

Mercator

Revised 11/06/2007
Red text depicts changes made since 07/20/2005


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

Nj—number of points along a parallel  
35-38

Nj—number of points along a meridian
39-42
 La1 ― latitude of first grid point
43-46
 Lo1 ― longitude of first grid point
47
 Resolution and component flags (see Flag Table 3.3)
48-51

LaD — latitude(s) at which the Mercator projection intersects the Earth (Latitude(s) where Di and Dj are specified)  

52-55
 La2 ― latitude of last grid point
56-59

Lo2 — longitude of last grid point   

60 Scanning mode (flags — see Flag Table 3.4)
61-64

Orientation of the grid, angle between i direction on the map and the Equator  (see Note1)     

65-68

Dj —  longitudinal direction grid length (see Note 2)
69-72

Dj ― latitudinal direction grid length  (see Note 2)
73-nn

List of number of points along each meridian or parallel
(These octets are only present for quasi-regular grids as described in notes 2 and 3 of GDT 3.1)


Notes:

1.  Limited to the range of  0 to 90 degrees; if the angle of orientation of the grid is neither 0 nor 90 degrees, Di and Dj must be equal to each other.

2.  Grid lengths are in units of 10-3  m, at the latitude specified by LaD.

3.  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 metres.


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