CrIS SDR Radiometric Assessment Using CRTM

The Crosstrack Infrared Sensor (CrIS) is a spaceborne Fourier Transform Spectrometer (FTS) that was launched into orbit on October 28th 2011 onboard the SUOMI NPP satellite. As part of the ongoing calibration and validation activities, the radiance residuals (observed minus calculated) are analyzed in order to assess the radiometric accuracy. For over 1,000 cases, the measured spectra correspond to location over ocean for cloud free scenes. The top of atmosphere (TOA) radiance is calculated from the modeled sea surface temperature at the CrIS footprint location, the ECMWF atmospheric state, and the Community Radiative Transfer Model (CRTM). The radiance residual shows a radiometric agreement of 0.2K over the window channels. The CrIS SDR radiance products (spectra, geolocation, noise) are essential for assimilation into the NWP weather forecasting system.