Publications

Li, H; He, XQ; Bai, Y; Chen, XY; Gong, F; Zhu, QK; Hu, ZF (2016). Assessment of satellite retrieval algorithms for chlorophyll-a concentration under high solar zenith angle. REMOTE SENSING OF THE OCEAN, SEA ICE, COASTAL WATERS, AND LARGE WATER REGIONS 2016, 9999, UNSP 99990U.

Abstract
Numerous empirical algorithms have been operationally used to retrieve the global ocean chlorophyll-a concentration (Chla) from ocean color satellite data, e.g., the OC4V4 algorithm for SeaWiFS and OC3M for MODIS. However, the algorithms have been established and validated based on the in situ data mainly measured under low to moderate solar zenith angle (< 70 degrees). Currently, with the development of the geostationary satellite ocean color remote sensing which observes from early morning to later afternoon, it is necessary to know whether the empirical Chla algorithms could be applied to high solar zenith angle. In this study, the performances of seven widely-used Chla algorithms under high solar zenith angles, i.e., OC2, OC3M, OC3V, OC4V4, CLARK, OCI, and YOC algorithms, were evaluated using the NOMAD global in situ ocean color dataset. The results showed that the performances of all the seven algorithms decreased significantly under high solar zenith angles as compared to those under low-moderate solar zenith angles. For instance, for the OC4V4 algorithm, the relative percent difference (RPD) and root-mean-square error (RMSE) were 13.78% and 1.66 mu g/l for the whole dataset, and 3.95% and 1.49 mu g/l for the solar zenith angles ranged from 30 degrees to 40 degrees, respectively. However, the RPD and RMSE increased to 30.45% and 6.10 mu g/l for solar zenith angle larger than 70 degrees.

DOI:
10.1117/12.2240164

ISSN:
0277-786X