Enhancements of Infrared Hyperspectral Spectrometer Spectral Calibration

The National Oceanic and Atmospheric Administration’s (NOAA’s) Geostationary eXtended Observations (GeoXO) series satellites are planned to follow the Geostationary Operational Environmental Satellite (GOES)-R series satellites in 2032 and beyond. GeoXO will provide the nation continuity of environmental imagery over the western hemisphere, with observational improvements where feasible. The GeoXO Sounder (GXS) will provide level 1b calibrated and navigated radiances in the midwave infrared (MWIR) and the longwave infrared (LWIR). The level 1b data will be used for vertical profiles retrievals of atmospheric temperature and moisture. GXS data and associated retrievals will not only be employed by National Weather Service (NWS) forecasters in near real time, but also will be used for numerical weather prediction (NWP) models. For NWP to fully utilize GXS data, the GXS spectral information must be precisely captured, and spectrally corrected ss needed for any instrument artifacts, to provide a fixed spectral grid that is temporally stable. The GXS requirements necessitate spectral stability at the level 1b for all spatial locations. A cross-correlation correction methodology was initially explored, employing a reference spectrum compared to shifted spectra. Although this method provided spectral correction over limited spectral range, it was insufficient in the presence of instrument optical aberrations. If spectral oversampling is possible, improved spectral correction in the presence of optical aberrations can be achieved. Additionally, nearly-simultaneous observations of a scanned uniform earth scene for all detectors can further refine and improve the spectral correction using the initial cross-correlation method above. Model spectra with artifacts were employed for assessing spectral corrections in the presence of aberrations. Resulting analysis, supporting that GXS data could be corrected by this method to levels approaching CrIS performance, will be discussed.

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This material is based upon work supported by the Dept of Commerce under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Dept of Commerce

Correspondence: Owen.McElhinney@ll.mit.edu