Abstract
The Cross-track Infrared Sounder (CrIS) sensor was launched on the Suomi NPP spacecraft October 28, 2011. The CrIS sensor is a Michelson interferometer with a 3 x 3 detectors for each of three spectral bands: LWIR 650-1095 wavenumbers, MWIR 1210-1750 wavenumbers and SWIR 2155-2550 wavenumbers. The CrIS sensor is performing very well and is generally exceeding the noise, radiometric and spectral performance requirements for its primary weather sensing mission. However, for climate change applications it becomes useful to push the radiometric calibration accuracy to the highest possible accuracy. The CrIS sensor is not actively temperature controlled so the sensor temperature varies due to the ever changing geometry of the earth and sun. Passing over different earth temperature regions also affects the sensor system temperatures. The central interferometer core experiences very little temperature change, but some of the outlying components such as the scene select mirror and the scan baffle change much more. Frequent calibrations using views to cold space and the internal calibration target reduce the radiometric uncertainties due to temperature variations but there are still some residual effects on calibration. Analysis of these residual effects will be presented.
CrIS Sensor Temperature Effects on CrIS Radiometric Performance
The Cross-track Infrared Sounder (CrIS) sensor was launched on the Suomi NPP spacecraft October 28, 2011. The CrIS sensor is a Michelson interferometer with a 3 x 3 detectors for each of three spectral bands: LWIR 650-1095 wavenumbers, MWIR 1210-1750 wavenumbers and SWIR 2155-2550 wavenumbers. The CrIS sensor is performing very well and is generally exceeding the noise, radiometric and spectral performance requirements for its primary weather sensing mission. However, for climate change applications it becomes useful to push the radiometric calibration accuracy to the highest possible accuracy. The CrIS sensor is not actively temperature controlled so the sensor temperature varies due to the ever changing geometry of the earth and sun. Passing over different earth temperature regions also affects the sensor system temperatures. The central interferometer core experiences very little temperature change, but some of the outlying components such as the scene select mirror and the scan baffle change much more. Frequent calibrations using views to cold space and the internal calibration target reduce the radiometric uncertainties due to temperature variations but there are still some residual effects on calibration. Analysis of these residual effects will be presented.