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利用2012年和2013年冬季长江口邻近海域的实测数据,分析了该区域漫衰减系数光谱特征,490nm波段向下漫衰减系数(Kd(490))的空间分布及影响因子,建立了该研究区域新的冬季漫衰减系数反演模型,并建立了研究区域内Kd(490)与有效光合辐射衰减系数(Kd(PAR))的关系。结果表明:长江口邻近区域Kd490值随着离岸距离的减小逐渐增大,最大值达到了1.8m-1,杭州湾邻近区域情况类似,舟山岛附近出现了Kd(490)的最大值2.8m-1。总悬浮物对Kd(490)的影响较大,悬浮物浓度与Kd(490)相关度大于0.86。黄色物质和叶绿素a对其影响较小,与Kd(490)相关度均小于0.25。本文建立了三波段遥感反射率与Kd(490)的反演模式:lg[Kd(490)]=a[Rrs(590)/Rrs(510)]+b[Rrs(670)/Rrs(510)],对比反演与实测结果显示:均方根误差为0.098m-1,平均相对误差为12.43%,决定系数为0.916;光合有效辐射衰减系数(Kd(PAR))与Kd(490)的关系:Kd(PAR)=0.495exp(0.8602Kd(490))-0.2217,对比反演与实测结果显示:均方根误差为0.102m-1,平均相对误差为14.62%,决定系数为0.927。
The spectral characteristics of the diffuse attenuation coefficient, the spatial distribution and influencing factors of the diffuse attenuation coefficient (Kd (490)) spreading downward in the 490nm band were analyzed by using the measured data of the adjacent estuaries in the Yangtze River estuary in 2012 and 2013, New winter diffuse attenuation coefficient inversion model was established and the relationship between Kd (490) and effective radiation attenuation coefficient (Kd (PAR)) in the study area was established. The results show that the value of Kd490 in the vicinity of the Changjiang Estuary gradually increases with the decrease of the offshore distance, and the maximum reaches 1.8m-1. The situation in the vicinity of Hangzhou Bay is similar, and the maximum value of Kd (490) m-1. The total suspended solids have a greater impact on Kd (490), and the correlation between the concentration of suspended solids and Kd (490) is greater than 0.86. Yellow matter and chlorophyll a had less influence on it, and the correlation with Kd (490) was less than 0.25. In this paper, the inversion model of three-band remote sensing reflectivity and Kd (490) is established: lg [Kd (490)] = a [Rrs (590) / Rrs (510)] + b [Rrs (670) / Rrs ]. The contrast inversion and measured results show that the root mean square error is 0.098m-1, the average relative error is 12.43% and the coefficient of determination is 0.916. The relationship between Kd (PAR) and Kd (490) : Kd (PAR) = 0.495exp (0.8602Kd (490)) - 0.2217. Contrast inversion and measured results show that the root mean square error is 0.102m-1, the average relative error is 14.62% and the coefficient of determination is 0.927.