Duan Hong-Tao, Ma Rong-Hua, Zhang Yuan-Zhi, Zhang Bai
State Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Jan;29(1):161-4.
Hyperspectral remote sensing offers the potential to detect water quality variables such as Chl-a by using narrow spectral channels of less than 10 nm, which could otherwise be masked by broadband satellites such as Landsat TM. Fluorescence peak of the red region is very important for the remote sensing of inland and coastal waters, which is unique to phytoplankton Chl-a that takes place in this region. Based on in situ water sampling and field spectral measurement from 2004 to 2006 in Nanhu Lake, the features of the spectral reflectance were analyzed in detail with peak position shift. The results showed: An exponential fitting model, peak position = a(Chl-a)b, was developed between chlorophyll-a concentration and fluorescence peak shift, where a varies between 686.11 and 686.29, while b between 0.0062 and 0.0065. It was found that the better the spectral resolution, the higher the precision of the model. Except that, the average of peak shift showed a high correlation with the average of different Chl-a grades, and the determination coefficient (R2) was higher than 0.81. It contributed significantly to the increase in the accuracy of the derivation of chlorophyll values from remote sensing data in Nanhu Lake. There is satisfactory correspondence between hyperspectral models and chl-a concentration, therefore, it is possible to monitor the water quality of Nanhu lake throngh the hyperspetral remote sensing data.
高光谱遥感能够利用小于10纳米的窄光谱通道来检测诸如叶绿素a等水质变量，而这些变量在诸如陆地卫星专题制图仪等宽波段卫星数据中可能会被掩盖。红色区域的荧光峰对于内陆和沿海水域的遥感监测非常重要，这是浮游植物叶绿素a在该区域所特有的。基于2004年至2006年在南湖进行的现场水样采集和野外光谱测量，详细分析了光谱反射率特征及其峰值位置偏移情况。结果表明：建立了叶绿素a浓度与荧光峰偏移之间的指数拟合模型，即峰值位置=a(叶绿素a)b，其中a在686.11至686.29之间变化，b在0.0062至0.0065之间变化。研究发现，光谱分辨率越高，模型精度越高。除此之外，峰值偏移平均值与不同叶绿素a等级的平均值呈现出高度相关性，决定系数（R2）高于0.81。这对提高南湖遥感数据叶绿素值反演精度有显著贡献。高光谱模型与叶绿素a浓度之间具有良好的对应关系，因此，利用高光谱遥感数据监测南湖水质是可行的。
