A refined empirical line approach for reflectance factor retrieval from Landsat-5 TM and landsat-7 ETM+

Moran, M. Susan; Bryant, Ross; Thome, K.; Ni, Wanmei; Nouvellon, Yann; Gonzalez-Dugo, M.P.; Qi, J.; Clarke, T.R.

A refined empirical line approach for reflectance factor retrieval from Landsat-5 TM and landsat-7 ETM+

2001

The recent launch of Landsat-7 ETM+ extends the uninterrupted stream of TM and ETM+ images to a potential span of 32 years. This exceptional image set will allow long-term studies of natural resources, but will require an operational method for converting image digital number (dn) to the temporally comparable surface reflectance factor (psa). A refinement to the empirical line (EL) approach for reflectance factor retrieval (RFR) from the Landsat-5 and -7 TM and ETM+ has been proposed. The refined empirical line (REL) approach requires only one within-scene calibration target, minimal field measurements of that target, and a reasonable estimate of dn for psX=0 using a radiative transfer model or values provided by this analysis. This study showed that the REL approach worked well for a 10-year Landsat-5 TM and Landsat-7 ETM+ image set in Arizona and psx was retrieved with an estimated accuracy of 0.01. A quantitative approach was proposed to determine the suitability of a within-scene target for the REL approach, and based on historical measurements, a variety of targets met the size and brightness requirements for the REL approach. This operational approach for RFR should encourage long-term investigations of natural resources to answer critical questions regarding resource management and effects of climate changes. (Résumé d'auteur)

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