Describes how to treat the incoming SH, before the transformation to grid points.
For other keywords controlling the interpolation see the diagram below.
Possible values are
|NONE||Disables any truncation before the transformation, i.e. uses the archived spectral resolution.|
A formula is used to truncate the spectral series to correspond to the equivalent linear Gaussian grid. This is the default behaviour
|Specific truncation to be applied, e.g. TRUNCATION=179 truncates the Spectral harmonics input field to T179.|
|OFF||reserved MARS value that resets the value inherited, effectively removing the keyword from the request which results in AUTO being applied.|
This keyword cannot be specified. Behaviour is as MARS with the default value, i.e. AUTO.