Continuous calibration improvement in solar reflective bands: Landsat 5 through Landsat 8

Launched in February 2013, the Operational Land Imager (OLI) on-board Landsat 8 continues to perform exceedingly well and provides high quality science data globally. Several design enhancements have been made in the OLI instrument relative to prior Landsat instruments: pushbroom imaging which provides substantially improved Signal-to-Noise Ratio (SNR), spectral bandpasses refinement to avoid atmospheric absorption features, 12 bit data resolution to provide a larger dynamic range that limits the saturation level and increases SNR, a set of well-designed onboard calibrators to monitor the stability of the sensor. Some of these changes, such as refinements in spectral bandpasses compared to earlier Landsats and a well-designed on-board calibrator have a direct impact on the improved radiometric calibration performance of the instrument from both the stability of the response and the ability to track the changes. The on-board calibrator lamps and diffusers indicate that the instrument drift is generally < 0.1% per year across the bands. The refined bandpasses of the OLI indicate that temporal uncertainty of better than 0.5% is possible when the instrument is trended over vicarious targets such as Pseudo Invariant Calibration Sites (PICS), a level of precision that was never achieved with the earlier Landsat instruments. With three years of data available, the stability measurements indicated by on-board calibrators and PICS agree to 0.5%, which is much better compared to the earlier Landsats, which is very encouraging and bodes well for the future Landsat missions too.