Inversion of total suspended matter concentration in turbid water based on the characteristic of chlorophyll fluorescence peak

Abstract

The optical property of inland water is very complex, and inversion of water components concentration of inland water body is hotspot and difficulty problem in water quality remote sensing. The remote sensing reflectance and water qualities of 67 stations were acquired in the Lake Taihu in October, 2004. Basing on the characteristic spectral analysis, it was obvious that the water body spectral character in Lake Taihu in autumn was dominated by the total suspended matter (TSM). The properties of the chlorophyll fluorescence peak mainly reflect the variation of the concentration of TSM. Hereby, we established the relation between the properties of the chlorophyll fluorescence peak and the concentration of TSM based on in-situ remote sensing reflectance with 1nm bandwith and water quality measurements. There were good response relationships between them. Making a concrete analysis ofthe correlation relationship between the absolute height of fluoresce peak, the height above the reference baseline, the normalized height referred to the maximum reflectance about 560nm in green band and 810nm in infrared band, the integral area (including the total integral area, the integral area between the spectral curve and the reference baseline, the integral area below the reference baseline and the wavelength axis) and the concentration of TSM. Their correlation coefficients were 0.8822, 0.7483, 0.8901, 0.8547, 0.8927, 0.8877 and 0.8632 respectively, and the average relative error were 27.25%, 41.03%, 27.11%, 25.75%, 24.91%, 25.47% and 27.54% respectively. The inversion accuracy of the total integral area method is obvious better than the reference baseline height method. No outstanding correlation relationship between chlorophyll concentration and fluorescence peak position were found based on reflectance spectra. The results show that chlorophyll fluorescence properties are effective in detecting TSM concentration in turbid inland water body, which provide a new optional sensitive band to retrieval TSM concentration in complex waters.