水体校正模型在三亚湾的验证及分析

Validation and Analysis of Water Column Correction Algorithm at Sanya Bay

水体校正一直是光学浅水遥感检测中的重点难题。为了提高三亚湾底质遥感监测精度,分别采用理想水体光辐射分布和Christian模型剔除水体信号的影响,尝试从水面之下遥感反射率信号中提取其底质光谱反射率值。结果表明,两种模型模拟结果差异较大,其模拟与实测值的相关性分别是0.93和0.26。经分析认为Christian模型在三亚湾湾内水域失效的这一结果与三亚湾光学浅水和光学深水的差异性相关。三亚湾湾内水域光学性质复杂,光学参数随着地理坐标位置变化较大,即使在光学浅水水域内的邻近站点,其衰减系数也是具有较大差异的。因而,Christian的模型在此区域很难发挥出优势。

Water column correction has been a substantial challenge for remote sensing.In order to improve the accuracy of coastal ocean monitoring where optical properties are complex,optical property of shallow water at Sanya Bay and the suitable water column correction algorithms were studies in the present paper.The authors extracted the bottom reflectance without water column effects by using a water column correction algorithm which is based on the simulation of the underwater light field in idealized water.And we compared the results which were calculated by the model and Christian＇s model respectively.Based on a detailed analysis,we concluded that： Because the optical properties of Sanya Bay are complex and vary greatly with location,Christian＇s model lost its advantage in the area.Conversely,the bottom reflectance calculating by the algorithm based on the simulation of the underwater light field in idealized water agreed well with in situ measured bottom reflectance,although the reflectance was lower than in situ measured reflectance value between 400 and 500 nm.So,it is reasonable to extract bottom information by using the water column correction algorithm in local bay area where optical properties are complex.