NSA/SKYRAD/C2 - NIP Frost or Ice
Frost or ice likely obstructed the NIP as short_direct_normal values were near zero for the affected time periods. These times correspond to mornings before OPS has the opportunity to clean the instruments. Clear days at Atqusuk are rare and the NIP instrument can very well be ice covered and it won't be apparent in the data. In this case the clear days and overnight icing made the icing issue very apparent.
Data are not recoverable.