Wavelength Registration Correction for the S-NPP OMPS Nadir Instruments

On orbit wavelength registration is one of the most important challenges facing the OMPS nadir instruments since the launch of the S-NPP satellite in 2011. Both the Nadir Profiler (NP) and Nadir Mapper (NM) instruments show a cyclical variability in the wavelength registration, with a seasonal +/-0.02 nm amplitude for the NP, and an intra-orbital +/- 0.06 nm amplitude for the NM, with a measured impact of about 2% on the radiance for both NP and NM. We present the results of our study of multi-year data for both instruments and the approaches employed by the NOAA STAR OMPS SDR team to correct the wavelength registration. Methods presented include both a temperature dependent correction and a time dependent look up table. Registration errors are reduced to less than 0.01 nm, and the impact on the radiance to less than 1%, for both instruments, better than the OMPS S-NPP requirements.