Atmospheric uncertainties due to overpass differences were deemed to be a major source of uncertainty, especially at longer wavelengths as analysis over Libya 4 PICS showed that a difference of 1%–4% can be expected depending on atmospheric conditions at the time of year and overpass. PICS-based calibration has been vital to the general calibration/validation strategy of the Landsat instruments. As more images become available in the archive, the Calibration Validation Team (CVT) at NASA Goddard Space Flight Center(GSFC), the USGS Earth Resources Observation and Science (EROS) Center and SDSU will continue to monitor OLI trending over PICS and this will provide an independent means (other than onboard calibrators) to monitor the stability of the OLI instrument. Future work also includes using PICS-based inter-calibration approaches to validate all the Landsat sensors (Landsat 1–Landsat 8) with respect to a
consistent radiometric scale. This work will be done, first in terms of relative calibration and then by absolute calibration.