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Why is the Ratio of Reflectivity Effective for Chlorophyll Estimation in the Lake Water?
Institute of industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
Received: 30 May 2010; in revised form: 13 June 2010 / Accepted: 7 July 2010 / Published: 9 July 2010
Abstract: The reasons why it is effective to estimate the chlorophyll-a concentration with the ratio of spectral radiance reflectance at the red light region and near infrared regions were shown in theory using a two-flow model. It was found that all of the backscattering coefficients can consequently be ignored by using the ratio of spectral radiance reflectance, which is the ratio of the upward radiance to the downward irradiance, at the red light and near infrared regions. In other words, the ratio can be expressed by using only absorption coefficients, which are more stable for measurement than backscattering coefficients. In addition, the band selection is crucial for producing the band ratio when the chlorophyll-a concentration is estimated without the effects of backscattering. I conclude that the two wavelengths selected must be close, but one must be within the absorption range of chlorophyll-a, and the other must be outside of the absorption range of chlorophyll-a, in order to accurately estimate the chlorophyll-a concentration.
Keywords: band selection; lake Kasumigaura; radiative transfer model; spectral signature; vegetation index
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MDPI and ACS Style
Oki, K. Why is the Ratio of Reflectivity Effective for Chlorophyll Estimation in the Lake Water? Remote Sens. 2010, 2, 1722-1730.
Oki K. Why is the Ratio of Reflectivity Effective for Chlorophyll Estimation in the Lake Water? Remote Sensing. 2010; 2(7):1722-1730.
Oki, Kazuo. 2010. "Why is the Ratio of Reflectivity Effective for Chlorophyll Estimation in the Lake Water?" Remote Sens. 2, no. 7: 1722-1730.