Impact of Normalization Intervals for Hyperspectral Reflectance on Estimation of Chlorophyll-a in Lake Tai, China

To investigate the effect of normalizing spectral interval on estimating chlorophyll concentration, hyperspectral reflectance collected in Lake Tai, China was normalized with the averaged reflectance of various spectral intervals, and the correlation of the normalized reflectance to chlorophyll concentration was analyzed. The results indicate that the maxima of positive correlation coefficients follows a parabola, while the maxima of negative correlation coefficients increase when the normalizing spectral intervals change from shorter to longer spectral regions, and the magnitude for negative correlation is larger than one for positive correlation when normalizing spectral intervals are beyond 485-815 nm. When normalizing spectral intervals are between 415-745 and 495-825 nm, normalized reflectance is most highly correlated to chlorophyll abundance with a value of 0.91 or larger. This result is very valuable for determining an optimal spectral interval to realize real-time monitoring of chlorophyll-a concentration with remote sensing techniques.