[Bio-optical model of total suspended matter based on reflectance in the near infrared wave band for case-II waters].
From August to October, 2006, reflectance spectra were measured in a turbid Case-Il waters condition with an ASD FieldSpec spectrometer for a total of 58 samples. Based on the observation of reflectance curves, spectral analysis was carried out over 400-1200 nm. Showing the typical character of Case-II waters, the reflectance values were generally higher than those in other similar studies. Strong backscattering of high concentration total suspended matter (TSM) contributed considerably to the total reflectance spectra in water. Two obvious TSM reflectance peaks were observed in the near infrared wave bands, i.e., 808 and 1067 nm, especially the latter one that was never reported before. The highest correlation coefficient between reflectance and concentrations of TSM existed at 873 nm. Based on the simplification of water inherent optical parameters in the near-infrared wave band, including absorption of TSM, Chlorophyll-a (Chl-a) and chromophoric dissolved organic matter (CDOM), and backscattering of pure water, Chl-a and CDOM, three empirical equations of the bio-optical model using reflectance at 808, 873 and 1067 nm respectively were established to estimate the concentrations of TSM. Compared with linear and exponential models, the bio-optical model showed fairly good performance with comparatively high determination coefficient (r2) and low root mean squared error (RMSE), which confirmed the applicability of the bio-optical model to retrieve concentrations of TSM effectively in turbid Case-II waters.
Xu
Jing-ping
JP
Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Changchun 130012, China. xjingping@gmail.com
Zhang
Bai
B
Song
Kai-shan
KS
Wang
Zong-ming
ZM
Duan
Hong-tao
HT
Chen
Ming
M
Yang
Fei
F
Li
Feng-xiu
FX
D005618:Fresh Water / Q000032:analysis*; D007259:Infrared Rays; D055095:Optics and Photonics