Updates of Moderate Resolution Imaging Spectroradiometer on-orbit calibration uncertainty assessments

TLDR

The MODIS instruments on NASA’s Terra and Aqua spacecraft have operated for more than 18 and 16 years, respectively, and have produced a broad range of freely distributed Earth remote‑sensing products. This paper reviews MODIS L1B calibration algorithms, updates sensor‑calibration uncertainty assessments to account for on‑orbit changes, and discusses remaining challenges and potential improvements to sustain data quality. MODIS collects data in 20 reflective solar bands and 16 thermal emissive bands (0.41–14.4 µm), producing L1B products that include top‑of‑atmosphere reflectance, radiances, and pixel‑level uncertainty indices.

Abstract

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments have successfully operated for more than 18 and 16 years, respectively, on-board the NASA's Earth Observing System Terra and Aqua spacecraft. Both Terra and Aqua MODIS have significantly contributed to the advance of global Earth remote sensing applications with a broad range of science products that have been continuously produced since the beginning of each mission and freely distributed to users worldwide. MODIS collects data in 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB), covering wavelengths from 0.41 to 14.4 μm. Its level 1B (L1B) data products, which provide the input for the MODIS high-level science products, include the top of the atmosphere reflectance factors for the RSB, radiances for both the RSB and TEB, and associated uncertainty indices (UI) at a pixel-by-pixel level. This paper provides a brief review of MODIS L1B calibration algorithms, including a number of improvements made in recent years. It presents an update of sensor calibration uncertainty assessments with a focus on several new contributors resulting from on-orbit changes in sensor characteristics, approaches developed to address these changes, and the impact due to on-orbit changes on the L1B data quality. Also discussed are remaining challenges and potential improvements to be made to continuously maintain sensor calibration and data quality, particularly those related to the quality of MODIS L1B uncertainty.