【摘要】 长江口水下三角洲地形地貌对于长江口航道安全、生态环境、海岸带工程等均具有重要意义,本次研究拟采用世界上第一颗静止水色卫星GOCI(Geostationary Ocean Color Imager)开展长江口K_d(490)的季节和潮汐变化规律研究,以期为采用机载激光测深提供预评估信息。研究得到结论如下:长江口及邻近海域水体为典型的二类水体,悬浮泥沙含量最高可由杭州湾内几千mg/L迅速降低至10 mg/L以下,因此,分段式的漫衰减系数反演算法适用于研究区域;K_d(490)反演结果表明长江口及邻近海域的K_d(490)值的季节变化特征表现为冬高夏低,春秋居中,长江冲淡水流量和季风是影响其季节变化的主要因素,而在一个潮周期内,K_d(490)值总体表现为低潮期低于高潮期,悬浮泥沙浓度和潮水的潮位是长江口及邻近海域的K_d(490)值的重要影响因素;研究指出,长江口及杭州湾内激光可探测深度约在5～22 m范围内,夏季退潮低潮位最适合激光雷达观测。由此可见,GOCI 8景/d,1景/h的分辨率可以实现K_d(490)的动态变化监控,而且可以实现在相同潮位下更为合理地描述K_d(490)值的季节变化,为机载激光雷达探测的进一步开展提供了技术支持。更多还原

【Abstract】 The topography and geomorphology of the subaqueous delta of the Yangtze River Estuary are of great significance to the safety of the Yangtze Estuary Channel, the ecological environment and coastal engineering. In this study, Geostationary Ocean Color Imager(COCI), the world’s first geostationary ocean color imager, is proposed to be used to explore the seasonal and tidal variation laws of K_d(490) in the Yangtze River Estuary.The feasibility of laser sounding in the sea areas is evaluated according to the variation characteristics of K_d(490). The conclusions are as follows. The Yangtze River Estuary and its adjacent waters are typical type II water. The maximum suspended sediment content can be rapidly reduced from 1 000 mg/L in the Hangzhou Bay to below 10 mg/L. Therefore, the piecewise diffuse attenuation coefficient inversion algorithm is suitable for the study area; the inversion results suggest that the seasonal variation characteristics of K_d(490) value in the Yangtze River Estuary and its adjacent sea areas are high in winter and low in summer, and moderate in spring and autumn. The main factors affecting its seasonal variation are the discharge of Yangtze diluted water and monsoon.In a tidal cycle, the K_d(490) value is generally lower in the low tide period than in the high tide period, and the suspended sediment concentration and the tidal level are important factors affecting K_d(490) values in the Yangtze River Estuary and its adjacent sea areas. In the Yangtze River Estuary and Hangzhou Bay, the laser detection depth is about 5 m to 22 m, and the summer ebb low tide lever is most suitable for lidar observation. It can be seen that GOCI’s daily resolution of 8 scenes per hour can realize the dynamic change monitoring of K_d(490).Moreover, it is possible to describe the seasonal variation of K_d(490) value more reasonably under the same tide level. The research provides technical support for the further development of airborne LiDAR detection.更多还原