Error Propagation From Aerosol Retrieval to Atmospheric Correction Due to Adjacency Effect for FORMOSAT-2 RSI Band


Homogeneous surface is usually assumed in aerosol retrieval for the dark target method. Retrieved aerosol optical depth can thus be overestimated. This error will also be propagated into retrieved surface reflectance during atmospheric correction, especially for high spatial resolution of 8 m for FORMOSAT-2 (also known as ROCSAT-2) RSI. The error in retrieved surface reflectance during atmospheric corrections induced by retrieved aerosol optical depth error due to adjacency effect over a dark target is studied in the green and red bands of FORMOSAT-2 RSI. The results show that significant errors in retrieved surface reflectance, i.e., larger than 0.01, may occur in most cases except at low contrast for a bright target. Such an error for a dark target is larger than that for a bright target for given contrast and haziness. Relatively, the error of retrieved surface reflectance is enhanced by the introduced error of aerosol optical depth in atmospheric correction for dark targets. The error can be larger than 35% for dark targets and less than 10% for bright targets. Hence, it is suggested that adjacency effect be considered from aerosol optical depth retrieval to surface reflectance retrieval in atmospheric correction except at low contrast for bright targets.

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