Publications

Liu, Y; Li, JS; Xiao, CC; Zhang, FF; Wang, SL; Yin, ZY; Wang, C; Zhang, B (2022). A Classification-Based, Semianalytical Approach for Estimating Water Clarity From a Hyperspectral Sensor Onboard the ZY1-02D Satellite. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 60, 4206714.

Abstract
Water clarity (Z(sd)) is a widely used quality indicator that can be estimated from remote sensing imagery. China's newest generation advanced hyperspectral imager (AHSI) onboard the ZY1-02D satellite is expected to enable accurate water clarity retrieval for inland waters, since AHSI can provide abundant band choices, while its 30-m spatial resolution is advantageous for monitoring small inland water bodies. In this study, to retrieve Z(sd) from the ZY1-02D imagery for inland waters with varying turbidities, we propose a classification-based, semianalytical method, in which the red/ blue band ratio is employed to distinguish clear to moderately turbid water and highly turbid waters. Two quasi-analytical algorithms (QAAs), QAA(v5) and QAA(m14), are used to estimate the total absorption coefficient [a(lambda)] and the backscattering coefficient [b(b)(lambda)] for clear to moderately turbid water and highly turbid waters, respectively. The estimated a(lambda) and b(b)(lambda) are utilized to obtain the diffuse attenuation coefficient K-d, followed by the Z(sd) calculations. Compared with 70 matchups of in situ measured Z(sd) values (0-6.5 m), the ZY1-02D image-derived Z(sd) achieved an R-2 of 0.98, with an average unbiased relative error and root mean square error of 29.1% and 0.52 m, respectively. In addition, the proposed method can yield Z(sd) with higher accuracies than that of optimized empirical models. Therefore, the ZY1-02D AHSI imagery can retrieve reliable Z(sd) for both clear (>3 m) and turbid waters (0-3.0 m), thereby serving as a useful satellite data source for monitoring the water clarity of large-scale inland water bodies.

DOI:
10.1109/TGRS.2022.3161651

ISSN:
1558-0644