长春南湖水体透明度高光谱定量模型研究

透明度是衡量水质优劣、评价湖泊富营养化的一个重要指标，高光谱遥感可有效反演透明度，较好解决了常规遥感中出现的问题。本研究利用野外高光谱仪在长春南湖夏季进行了反射光谱测量和同步水质采样分析，通过分析水体透明度与其高光谱反射率之间的相关关系，尝试采用多种半经验算法建立透明度高光谱定量模型，并进行了验证。结果表明：1）单波段、波段比值和一阶微分反演模型，确定性系数皆在0.74以上，RMSE小于透明度极值差，因此皆可以用于反演透明度；2）模型精度从高到低依次为：一阶微分模型、单波段模型和波段比值模型。该定量模型的建立，为今后利用成像光谱数据在南湖进行透明度大面积遥感反演研究提供了研究基础和科学依据，对内陆水体透明度反演也有一定的借鉴意义。

Evaluation of Secchi Disk Transparency by Using Field Spectral Measurements in Nanhu Lake,Changchun

Secchi disk transparency is a measure of the transparency of a water body, and it is influenced by the abundance of organic and inorganic particulate and dissolved matter. Secchi disk transparency may be determined from hyperspectral remote sensing data. The advantage of high spectral resolution reflectance data (hyperspectral data) is the possibility of quantitative analysis due to diagnostic absorption bands. This study was conducted to establish correlations between hyperspectral reflectance spectra and secchi disk transparency in Nanhu Lake, Changchun．Reflectance spectra were measured from June to September in 2004, with ASD FieldSpec spectrometer. Based on in situ water sampling and reflectance measurements, algorithms have been developed. The single band R520nm, the spectra ratio of (R530-R860)/(R740-R860), and the reflectance first-derivative of 610nm, which showed a linear relationship, were all found to be significantly correlated with secchi disk transparency. The algorithms have been applied to evaluate secchi disk transparency, and the determination coefficient R2 gained using the first-derivative of 610nm was higher than that gained with other two models. The validation using independent in situ reference data showed RMSE of 4.97–9.68 m. There is satisfactory correspondence between hyperspectral models and secchi disk transparency, and it is possible to monitor the water quality of Nanhu Lake using hyperspetral remote sensing data.