Cross-Comparison of Ocean Color Products Derived from Tiangong-2/WIS and GOCI in the Yangtze Estuary, China
Suspended particulate matter (SPM) is one of the key issues in estuarine and coastal waters, which is widely used in water quality assessment, river erosion and siltation, and port engineering. The Wide-band Imaging Spectrometer (WIS) as one of the payloads mounted on the Tiangong-2 (TG-2) is a successor of spaceborne ocean color sensors. In this study, data from Geostationary Ocean Color Imager (GOCI) launched by Korean ocean satellite center (KOSC) and in situ measurements are used to compare and evaluate data products acquired by the TG-2/WIS. Comparison results show that the TOA reflectances of TG-2 /WIS and GOCI agree well at visible and near-infrared bands. Atmospherically-corrected remote sensing reflectances (Rrs) from TG-2/WIS and GOCI have good correspondences from visible to near-infrared bands Their root mean square differences (RMSD) at 660 and 745 nm are less than 0.04 sr−1, and the TG2/WIS observed Rrs is slightly underestimated at 865 nm with the slope of 0.77. Moreover, the derived SPM concentrations from TG-2/WIS and GOCI data are quite approximate. It implies that the accuracy of TG-2/WIS data products can meet the need of marine environmental monitoring in estuaries and coastal regions. In addition, in contrast to other ocean color sensors, the TG-2/WIS may have greater potentials of water color applications, especially for meso- and small-scale phenomena and optically complex waters, due to its multi-bands and high spatial resolution advantages.
KeywordsTiangong-2 Wide-band Imaging Spectrometer GOCI Cross-comparison Suspended particulate matter Yangtze estuary
This study is supported by National Key R&D Program of China (no. 2016YFE0103200) and NSFC projects (no. 41771378, 51739005). KORDI/KOSC is grateful for the GOCI imagery. Thanks to China Manned Space Engineering for providing space science and application data products of Tiangong-2.
- 2.Chen, J., Ni, X., Mao, Z., Wang, Y., Liang, L., Gong, F.: Remote sensing and buoy based effect analysis of typhoon on hypoxia off the Changjiang (Yangtze) estuary. In: Proceedings of SPIE - The International Society for Optical Engineering. 8532. 11 (2012)Google Scholar
- 3.Du, J.L., Yang, S.L., Zhang, W.X., Li, P., Zhao, H.Y.: Study of influence on erosion and accumulation of Jiuduansha Tidal Island by deep-water channel project at north passage of the Yangtze River. Ocean Eng. 23, 78 (2005)Google Scholar
- 5.Yu, X.L.: Retrieval of Suspended Matter Concentration and Reconstruction of Missing Data Based on GOCI in Bohai and Yellow Sea. Ocean University of China (2013)Google Scholar
- 6.Peng, X.Y.: Retrivals of Surface Suspended Particulate Matter Concentration and Its Variation In Yangtze River estuary Using Multiple Polar-Orbiting and Geostationary Satellites. East China Normal University (2015)Google Scholar
- 7.Frouin, R. (ed.): In-flight Calibration of Satellite Ocean-Colour Sensors. Reports of the International Ocean-Colour Coordinating Group, No. 14, IOCCG, Dartmouth, CanadaGoogle Scholar
- 13.Zhao, J., Qing, H.E., Wang, X.Y., Guo, L.C.: Field observations on the characteristics of current and sediment of the south and north branches in the yangtze estuary. Resources & Environment in the Yangtze Basin (2015)Google Scholar