Using in situ and Satellite Hyperspectral Data to Estimate the Surface Suspended Sediments Concentrations in the Pearl River Estuary

摘要

In situ remote sensing reflectance $(R{rm rs})$ collected during 2004–2006 and the planetary reflectance $(R{rm p})$ derived from EO-1/Hyperion image, are tested for estimating the surface total suspended matter (TSM), total inorganic particles (TIP) and water turbidity in the Pearl River Estuary (PRE). The in situ data show that the content of TIP and turbidity is proportional to the concentration of TSM which ranges from 6 mg/L to 140 mg/L. The band-subtraction of $R{rm rs}$ at 610 nm and 600 nm, $[R{rm rs}(610)-R{rm rs}(600)]$, and the subtraction of the 26th and 25th Hyperion bands (609.97 nm and 599.80 nm), $[R{rm p}({rm B}26)-R{rm p}({rm B}25)]$, are used in an exponential regression model to estimate the TSM concentrations, the mean relative errors between the estimated and measured TSM are 27.2% and 23.3%, respectively for $R{rm rs}$ and $R{rm p}$, and the root mean square errors of estimation are 12.6 mg/L and 5.9 mg/L, respectively. This band-subtraction of two neighboring bands shows better performance than several popular single-band and band-combination models. This good performance may be mainly attributed to the band-subtraction of the two neighboring bands which improves the sensitivity of reflectance to suspended sediments by reducing the background impacts from water surface reflection and path radiance at the specific wavelengths. These methods and findings with the high spatial and high spectral resolution data may be used for the remote sensing of turbid estuary waters al- hough further validation work with a wider range of TSM concentration may be necessary.