Total suspended matter observation in the Pearl River estuary from in situ and MERIS data

Based on the cruise data collected in the Pearl River estuary (PRE) in May 2008, an empirical two-band model by using the ratio of R (rs) at 629 and 671 nm was established to retrieve total suspended matter (TSM) concentration with the determination coefficient (R-2) of 0.854, mean relative error (MRE) of 7.483%, and root-mean-square error (RMSE) of 1.295 mg L (-aEuro parts per thousand 1). To match with medium resolution imaging spectrometer (MERIS) bands, in situ remote sensing reflectance was re-sampled to the bandwidth of 10 nm. The relationship between TSM and re-sampled R (rs) at 620 nm (MERIS band 6) and 665 nm (MERIS band 7) are obtained (R-2 = 0.748, RMSE = 1.697 mg L (-aEuro parts per thousand 1), MRE = 8.785%, n = 13). Additionally, to map the spatial distribution of TSM in the PRE, MERIS level_1B data were calibrated using a multiple linear regression model based on in situ R (rs). Another dataset collected in the PRE in January 2004 was used to validate the two-band model and also applied to map TSM distribution from MERIS image. The comparison between measured TSM values and modeled ones showed satisfactory results (R-2 = 0.753, MRE = 22.199%, and RMSE = 2.603 mg L (-aEuro parts per thousand 1)).