Octet No. | Contents |
---|---|

15-18 |
J ― pentagonal resolution parameter |

19-22 | K ― pentagonal resolution parameter |

23-26 | M ― pentagonal resolution parameter |

27 |
Representation type indicating
the method used to define the norm (see Code Table 3.6) |

28 |
Representation mode indicating
the order of the coefficients (see Code
Table 3.7) |

29-32 | Latitude of the pole of stretching |

33-36 | Longitude of the pole of stretching |

37-40 |
Stretching factor |

Notes:(1) The pentagonal representation of resolution is general. Some common truncations are special cases of the pentagonal one: Triangular: M = J = K Rhomboidal: K = J + M Trapezoidal: K = J, K > M (2) The stretching is defined by three parameters: (a) The latitude in degrees (measured in the model coordinate system) of the "pole of stretching"; (b) The longitude in degrees (measured in the model coordinate system) of the "pole of stretching"; and (c) The stretching factor C in units of 10 ^{-6 }
represented as an integer.The stretching is defined by representing data uniformly in a coordinate system with longitudeq λ and latitude θ ^{1},
where:θ ^{1} = sin^{-1}[(1- C^{2}) + (1 + C^{2})
sin θ] / [(1 + C^{2}) + (1 - C^{2}) sin θ ]and λ and θ are longitude and latitude in a coordinate system in which the "pole of stretching" is the northern pole. C = 1 gives uniform resolution, while C > 1 gives enhanced resolution around the pole of stretching. |