[H-TT13] Environmental Remote Sensing

[HTT13-P03] Removal of residual reflected skylight for accurate measurement of water-leaving reflectance

*Wei Yang¹, Bunkei Matsushita², Dalin Jiang² (1.Chiba University, 2.University of Tsukuba)

Keywords:remote sensing, inland lakes, above-water method, water-leaving reflectance

Water-leaving reflectance (Rrs) is crucial for remote estimation of water quality parameters. However, Rrs measured using the above-water approach usually suffers from residual reflected skylight, and thus its applicability is limited. In this study, we proposed a simple method, which only required the in situ Rrs spectrum itself as input, to further remove this effect in the in situ Rrs spectrum. The performance of the proposed method was evaluated using both simulation data and in situ Rrs spectra measured using a radiance sensor with a black tube. The results showed that the proposed method outperformed other existing methods and can be applied to various types of waters. From a comparison analysis using skylight-free in situ Rrs data, the proposed method showed the best performance with the smallest MAPE of 45% (MAPE ranged from 52% to 260% for other existing methods). In addition, the proposed method can improve the quality of Rrs spectra collected under various sky conditions (clear, scattered clouds and overcast), with an increased proportion of higher quality assurance scores. Two showcases indicate that the skylight corrections should be carried out for all above water approach-measured Rrs spectra before they are applied to develop water quality estimation algorithms or to evaluate the performances of atmospheric correction algorithms.