Landsat-8 Operational Land Imager Radiometric Calibration and Stability

TLDR

Calibration coefficients are included with the data products to enable conversion to radiance or reflectance units. The OLI was calibrated pre‑launch for spectral radiance using an NIST‑traceable integrating sphere and on‑orbit for reflectance using NIST‑traceable diffusers. Radiance and reflectance calibrations have uncertainties of ~3 % and ~2 %, respectively, and the sensor has remained stable to better than 0.3 % (except a ~1 % degradation in the shortest band), with some bands showing up to 5 % increased sensitivity and overall agreement with other instruments within uncertainties.

Abstract

The Landsat-8 Operational Land Imager (OLI) was radiometrically calibrated prior to launch in terms of spectral radiance, using an integrating sphere source traceable to National Institute of Standards and Technology (NIST) standards of spectral irradiance. It was calibrated on-orbit in terms of reflectance using diffusers characterized prior to launch using NIST traceable standards. The radiance calibration was performed with an uncertainty of ~3%; the reflectance calibration to an uncertainty of ~2%. On-orbit, multiple calibration techniques indicate that the sensor has been stable to better than 0.3% to date, with the exception of the shortest wavelength band, which has degraded about 1.0%. A transfer to orbit experiment conducted using the OLI’s heliostat-illuminated diffuser suggests that some bands increased in sensitivity on transition to orbit by as much as 5%, with an uncertainty of ~2.5%. On-orbit comparisons to other instruments and vicarious calibration techniques show the radiance (without a transfer to orbit adjustment), and reflectance calibrations generally agree with other instruments and ground measurements to within the uncertainties. Calibration coefficients are provided with the data products to convert to either radiance or reflectance units.