I noticed that your directory named "omps-nm", which suggests OMPS Nadir Mapper, actually contains OMPS Nadir Profiler data "OMPSNP.[date].nc". I would suggest renaming it to omps-np.
The actual OMPS Nadir Mapper data are in the directory "omps-nm-eff". Here, and in the OMI directory the "eff" stands for "efficiency factors", basically averaging kernels included with the data.
from Kris an nasa