In my limited understanding, the fundamental problem arises from the fact that
old radiosonde measurements show that the relative humidity of the upper troposphere has dropped as the earth has warmed.
They have gone through a number of types of
radiosondes and the satellite data would indicate the
measurement change with the new device since the new
radiosondes wouldn't match the satellite data and the
old radiosondes would This is the same problem — mandatory objective environmental test standards would give historic continuity.