We tested and modified the quasi-analytical algorithm (QAA) using 57 groups of field data collected in the spring of 2003 in the Yellow Sea and East China Sea. The QAA performs well in deriving total absorption coefficients of typical coastal waters. The average percentage difference (APD) is in a range of 13.9%–38.5% for the total absorption coefficient (13.9% at 440 nm), and differences in particle backscattering coefficient bbp(λ) are less than 50% (in the case of the updated QAA). To obtain improved results, we modified the QAA by adjusting the empirical relationships. The modified algorithm is then applied to the field data to test its performance. The APDs were 44.7%–46.6% for bbp(λ) and 9.9%–32.8% (9.9% at 555 nm) for the total absorption coefficient. This indicates that the modified QAA derives better results. We also used the modified model to derive phytoplankton pigment absorption (aph) and detritus and CDOM absorption (adg) coefficients. The APDs for aph and adg at 440 nm are 37.1% and 19.8%. In this paper, we discuss error sources using the measured dataset. More independent field data can improve this algorithm and derive better results.
In situ-satellite match-ups of radiometric data are established in the turbid waters of the Yellow Sea and the East China Sea.Inherent optical properties(IOPs) are retrieved by match-up radiometric data and multi-band quasi-analytical algorithm(QAA).By comparing in situ spectra-retrieved IOPs with the satellite ones of moderate resolution imaging spectroradiometer(MODIS) and medium resolution imaging spectrometer(MERIS),the accuracy of satellite-derived IOPs is quantified.The median of the absolute percentage difference is found to be approximately 20%for the total absorption coefficient a_t(λ) at green and blue-green bands,and 30%for particulate material backscattering coefficient b_(bp)(λ) throughout the visible bands.The spatial pattern and temporal variability of IOPs along the eastern coast of China are clarified based on satellite images and the QAA model.
