Abstract
The Cross-track Infrared Sounder (CrIS) instrument, one of the key payloads onboard the Suomi National Polar-orbiting Partnership (NPP) launched on Oct., 28, 2011, will provide well-calibrated high-spectral resolution data to enhance the weather forecasting models and also to improve the understanding of the climate phenomena. In this study, we evaluate and compare the overall radiometric calibration accuracy of CrIS with those of the Atmospheric Infrared Sounder (AIRS) on Aqua and the Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A using the GEO(geostationary)-LEO(Low Earth orbit) inter-calibration technique developed in the Global Space-based Inter-Calibration System (GSICS) project. This GSICS GEO-LEO inter-calibration is based on the collocated instrument measurements over a large area at the low- and middle-latitudes. Therefore it can be used to evaluate and investigate the calibration difference among the monitored instruments at various scan angles and temporal scales over a large brightness temperature (Tb) range. Using the broad-band GOES infrared measurements as the transfer, the preliminary results of the GEO-LEO inter-calibrations show that the CrIS Sensor Data Records (SDR) data calibrated with the Engineering Packet v32 is overall well-calibrated with comparable accuracy to AIRS and IASI. The CrIS Tb bias with respect to GOES agrees well with those of AIRS and IASI. The time-series of Tb difference between the CrIS and GOES infrared measurements is very stable and consistent with the Tb biases of AIRS and IASI with respect to GOES, indicating that the CrIS radiometric calibration is very stable during the study period. Evaluation and monitoring of the CrIS calibration accuracy will be continued over the coming calibration tuning event(s). Detailed work will be presented in the coming meeting.
Manuscript
Preliminary Comparison of Radiometric Calibration Performance among CrIS, AIRS and IASI Using GSICS GEO-LEO Inter-calibration
The Cross-track Infrared Sounder (CrIS) instrument, one of the key payloads onboard the Suomi National Polar-orbiting Partnership (NPP) launched on Oct., 28, 2011, will provide well-calibrated high-spectral resolution data to enhance the weather forecasting models and also to improve the understanding of the climate phenomena. In this study, we evaluate and compare the overall radiometric calibration accuracy of CrIS with those of the Atmospheric Infrared Sounder (AIRS) on Aqua and the Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A using the GEO(geostationary)-LEO(Low Earth orbit) inter-calibration technique developed in the Global Space-based Inter-Calibration System (GSICS) project. This GSICS GEO-LEO inter-calibration is based on the collocated instrument measurements over a large area at the low- and middle-latitudes. Therefore it can be used to evaluate and investigate the calibration difference among the monitored instruments at various scan angles and temporal scales over a large brightness temperature (Tb) range. Using the broad-band GOES infrared measurements as the transfer, the preliminary results of the GEO-LEO inter-calibrations show that the CrIS Sensor Data Records (SDR) data calibrated with the Engineering Packet v32 is overall well-calibrated with comparable accuracy to AIRS and IASI. The CrIS Tb bias with respect to GOES agrees well with those of AIRS and IASI. The time-series of Tb difference between the CrIS and GOES infrared measurements is very stable and consistent with the Tb biases of AIRS and IASI with respect to GOES, indicating that the CrIS radiometric calibration is very stable during the study period. Evaluation and monitoring of the CrIS calibration accuracy will be continued over the coming calibration tuning event(s). Detailed work will be presented in the coming meeting.