Operational monitoring of suspended matter distribution using MODIS images and numerical modelling

MODIS images of remote sensing reflectance of 250 m resolution at band 1 (620–670 nm) and high resolution (125 × 125 m) hydrodynamic model based on nonlinear shallow-water equations linked with particle transport model were used for monitoring the transport of suspended matter during the dredging works in Paldiski South Harbour, Pakri Bay, the southern part of Gulf of Finland from 15 April to 22 May 2003. Three MODIS images of remote sensing reflectance on cloudless days during dredging period and one image about 1 week after the dredging was completed were obtained. For laboratory analysis, water samples from sea surface were collected twice when MODIS images were available. In total, 48 data pairs of remote sensing reflectance and suspended matter concentration were used for calibration of MODIS images. Established linear regression model gave acceptable results on converting reflectance values into suspended matter concentrations. Suspended matter distributions from numerical model and remote sensing images compared reasonably well, so that numerical modelling of suspended matter transport and distributions can be used during cloudy period. In this case study, the analyses of remote sensing images and numerical model results indicated that the suspended matter concentrations and distribution patterns depended on dredging amounts and wind-forced currents.