4.1 What it is

  The "configuration 927" is the way how to use FullPOS to change the geometry and/or the resolution of a history spectral file. Actually, it is not a true configuration of the software ARPEGE/IFS/ALADIN, since the parameter NCONF should remain equal to 1 ; let us rather call it a configuration of the post-processing. In such configuration the horizontal interpolations are performed systematically before the vertical interpolations, and the dynamic variables are (usually) written out as spectral coefficients in the target spectral geometry^4.1.
As shown in the fancy picture below,

• Configuration "927" is to make a file ARPEGE, starting from a file ARPEGE (mostly used to change the resolution, the stretching and the pole of stretching in the 4D-Var suite),
• Configuration "E927" is to make a file ALADIN, starting from a file ARPEGE (for coupling ALADIN to ARPEGE),
• Configuration "EE927" is to make a file ALADIN, starting from a file ALADIN (for ALADIN nesting)