GRIB2 - DATA REPRESENTATION TEMPLATE 5.51

Spherical harmonics data - complex packing

Created 01/05/2005

Note:  For most templates, details of the packing process are described in Regulation 92.9.4.


Octet No. Contents
12-20
Same as data representation template 5.50
21-24 P― Laplacian scaling factor (expressed in 10-6 units)
25-26
Js ― pentagonal resolution parameter of the unpacked subset (see Note1)
27-28
Ks ― pentagonal resolution parameter of the unpacked subset (see Note1)
29-30
Ms ― pentagonal resolution parameter of the unpacked subset (see Note1)
31-34
Ts ― total number of values in the unpacked subset (see Note1)
35
Precision of the unpacked subset (see Code Table 5.7)


Notes:

(1) The unpacked subset is a set of values defined in the same way as the full set of values (on a spectrum limited to
Js, Ks and Ms ), but on which scaling and packing are not applied. Associated values are stored in octets 6 onwards
of section 7.

(2) The remaining coefficients are multiplied by (n x (n+1))p , scaled and packed. The operator associated with this
multiplication is derived from the Laplacian operator on the sphere.

(3) The retrieval formula for a coefficient of wave number n is then:
Y = (R+X x 2e ) x 10-d x (n x(n+1))-p where X is the packed scaled value associated with the coefficient.


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