S – NPP VIIRS On-orbit Uncertainty Estimate for Emissive Bands

The SNPP VIIRS instrument includes seven thermal emissive bands covering a range of 3.7 to 12 μm. The top of the atmosphere radiances and brightness temperatures generated by the instrument are used by the science community involved in environmental and climate research to create various science products. It is important to characterize the uncertainty of the VIIRS thermal bands measurements to ensure that the science accuracy requirements are being met. This work will focus on estimating the various error contributors and propagating the uncertainty inherent in the measurement to the product level using a standard formulation. Individual error sources include spectral and temperature uncertainties, uncertainty in the relative reflectance of the scan mirror, uncertainty in the detector response and radiance model parameters. Results of the error propagation are investigated using on-orbit data, covering various scene types as well as the retrieval of the on-board blackbody radiance. Estimates of the uncertainty are also made using prelaunch data from sensor level thermal vacuum testing, referenced to both the internal blackbody as well as a well characterized external blackbody. The prelaunch and postlaunch uncertainties are then both compared to the sensor specification to determine if the instrument is operating within the expected accuracy