Assessment of CrIS Radiometric Accuracy using Community Radiative Transfer Model (CRTM) and Double Difference Approach

The Cross-track infrared Sounder (CrIS) on Suomi National Polar-orbiting Partnership Satellite (NPP), is a very important Fourier transform spectrometer, and provides soundings of the atmosphere with 1305 channels. These soundings information will be used to enhance weather forecast and will help improve understanding of climate change. Quantifying the CrIS radiometric accuracy and creating a calibration link with other hyper-spectral infrared sensors such as Atmospheric Infrared Sounder (AIRS) on Aqua and Infrared Atmospheric Sounding Interferometer (IASI) on MetOp are crucial for creating fundamental climate data records and intercalibrating other infrared sensors. This study employs a double difference method to assess the CrIS radiance consistency with well-validated AIRS and IASI. This method uses the differences of CrIS/AIRS and CrIS/IASI relative to the radiative transfer (RT) simulations using the Community Radiative Transfer Model (CRTM) and European Centre for Medium-Range Weather Forecasts (ECMWF) forecast fields. The double difference method can remove the forward RT model and NWP model errors, and the intercomparisons are made on common spectral scale by convolving AIRS/IASI spectral to CrIS spectral. The double difference results between CrIS and AIRS, and CrIS and IASI over clear ocean scenes will be presented.