Remote Sensing of Spatiotemporal Variation of Apparent Optical Properties in Bohai Sea

It has been presented in this study, the evaluation of remote sensing reflectance (R_rs) derived from the atmospheric correction of Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua satellite. A switching algorithm was developed for the atmospheric correction. The evaluation shows that MODIS measured R_rs at visible bands compare reasonably well with in situ R_rs, with the mean ratios ranging from 0.955 to 1.374. The spatiotemporal variation of R_rs in Bohai sea is characterized using MODIS data from July 2002 to June 2014. It is noted from the time series of monthly mean R_rs and wind speed a time lag for the response of Rrs to wind. Significant linear relationship is found between the monthly mean R_rs and wind speed, with the correlation coefficients much higher than those between the annual mean R_rs and total river discharge, indicating that wind plays a more important role than river discharge in determining the variation of R_rs in Bohai sea. Strong seasonal variation is observed in the monthly mean R_rs, which is the lowest during July and August and increases to the maximum in January-February and then decreases. Using the entire archive of MODIS/Aqua data over Bohai sea, this study documents the apparent optical properties which serve as an indicator of sediment transport, providing a low-cost and efficient way for monitoring the marine environmental change and for demonstrating the effect from sediment transport on coastal morphology and ecosystem.