The problem consisted in excessive NESR values in the band AB and B and was due to the usage of a wrong offset auxiliary file (MIP_CO1_AX).
If the input MIP_CO1_AX is very different from the offsets in the L0 product,
all the offsets are flagged as invalid and the IPF uses the input MIP_CO1_AX as the good offset and subtract it from the scene.
In this case, the ZPD position of the offset and the ZPD position of the scene are mostly not aligned creating this oscillation in the calibrated spectrum.
This oscillation effect was already observed in the past in case of usage of a wrong MIP_CO1_AX auxiliary file.
The wrong MIPAS product has been removed and reprocessed at D-PAC with corrected auxiliary files.
