A path radiance estimation algorithm using reflectance measurements in radiometric control areas

Abstract

A new algorithm of path radiance estimation based on measurements of surface reflectance at radiometric control areas (RCAs) is proposed. Path radiance estimates of the proposed RCA-based method were compared against estimates of other methods including the dark object subtraction (DOS) method, the multi-band regression (MBR) technique and the covariance matrix method (CMM). The RCA-based method is superior to other methods based on three qualitative assessment criteria and a quantitative assessment based on measurements of molecule and aerosol optical depths (AODs) available from the Aerosol Robotic Network (AERONET) and Moderate Resolution Imaging Spectroradiometer (MODIS) data archive. Asphalt-paved surface, which could be easily identified in most images, was also found to be a good choice for RCAs. The DOS method and the CMM tend to overestimate path radiances. Although in our study the MBR technique and the RCA-based method seem to perform equally well, estimates of the MBR technique may be less reliable.

Acknowledgements

Analyses and visualizations of the MODIS AODs used in this article were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC. We acknowledge the MODIS mission scientists and associated NASA personnel for the production of the data used in this research effort. We also thank two anonymous reviewers for their constructive suggestions and comments which led to significant improvements of the manuscript.

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