CrIS High Resolution Hyperspectral Radiances

Abstract:

The CrIS hyperspectral sounder flying on Suomi-NPP
presently has reduced spectral resolution in the mid-wave and
short-wave spectral bands due to truncation of the interferograms in
orbit. CrIS has occasionally downlinked full interferograms for these
bands (0.8 cm max path, or 0.625 cm$^{-1}$ point spacing) for a few
orbits up to a full day. Starting Oct.1, 2014 CrIS will be commanded
to download full interferograms continuously for the remainder of the
mission, although NOAA will not immediately produce high-spectral
resolution Sensor Data Records (SDRs). Although the original
motivation for operating in high-resolution mode was improved spectral
calibration, these new data will also improve (1) vertical sensitivity
to water vapor, and (2) greatly increase the CrIS sensitivity to
carbon monoxide. This should improve (1) NWP data assimilation of
water vapor and (2) provide long-term continuity of carbon monoxide
retrievals begun with MOPITT on EOS-TERRA and AIRS on EOS-AQUA. We
have developed a SDR algorithm to produce calibrated high-spectral
resolution radiances which includes several improvements to the
existing CrIS SDR algorithm, and will present validation of these
high-spectral resolution radiances using a variety of techniques,
including bias evaluation versus NWP model data and inter-comparisons
to AIRS and IASI using simultaneous nadir overpasses (SNOs). The
authors are presently working to implement this algorithm for NASA
Suomi NPP Program production of Earth System Data Records.