查干湖叶绿素a浓度高光谱定量模型研究

叶绿素a含量能够在一定程度上反映水质状况,利用高光谱遥感可获得叶绿素a的诊断性光谱特性,较好解决了常规遥感中出现的问题.利用野外高光谱仪在查干湖进行了反射光谱测量和同步水质采样分析,通过分析水体叶绿素a浓度与其高光谱反射特征之间的相关关系,尝试采用多种半经验算法建立叶绿素a高光谱定量模型.结果表明:单波段光谱反射率与叶绿素a浓度的相关系数较小,不宜用于估算叶绿素a浓度,反射率比值法和一阶微分法与叶绿素a线性相关程度都比较高,决定系数分别为0.71和0.48,而且其显著水平p<0.01,皆可以用于叶绿素a的定量遥感,但反射率比值算法模拟效果好于一阶微分算法.这为今后利用星载高光谱传感器在查干湖进行叶绿素a浓度大面积遥感反演提供了研究基础.

Hyperspectral Remote Sensing of Chlorophyll-a in the Chagan Lake,China

An approach for the determination of chlorophyll-a from field reflectance spectra was presented in the Chagan Lake,China.Reflectance spectra were measured from May to September in 2004 with ASD FieldSpec spectrometer.Concurrently,water samples were collected directly from the lake to be analyzed in laboratory.Using correlations between the ground-truth data and combinations of spectral bands from the field spectral data,spectral indices including single band,spectral ratio,and reflectance first-derivative were developed which could be used to estimate chlorophyll-a.The latter two(spectral ratio and reflectance first-derivative) give better results with higher determination coefficient r²=0.71 and r²=0.48 with significance level p<0.01,and are applied to estimate chlorophyll-a concentration.There is a satisfactory correspondence between the two spectral indices and chlorophyll-a concentration, and these algorithms may prove to be useful tools to detect potential water quality problems of the Chagan Lake using remote sensing data.