The Research on the Variation of Chlorophyll-a in Bohai Sea Based on MODIS Data

Abstract

Chlorophyll-a (Chl-a) is an important parameter to characterize the degree of eutrophication in water. It has become an important index for water quality evaluation and is also one of the important water quality parameters that can be directly retrieved by remote sensing method. In this study, MODIS L1B data and OC3M Chl-a inversion model are used to invert Chl-a in the Bohai Sea from 2014 to 2019, the spatial and temporal variations of Chl-a in the Bohai Sea are investigated, and the influencing factors are analyzed. Results demonstrate that (1) the variations of Chl-a in different bays of the Bohai Sea have different trends. The Bohai bay and Laizhou bay show an upward trend, while the Liaodong bay and the central Bohai Sea show a downward trend. The concentration of Chl-a is related to the distance from the coast. The closer to the coast, the higher the concentration of Chl-a. (2) From 2014 to 2019, the overall concentration of Chl-a in Bohai Sea show a downward trend, the seasonal variation trend is relatively small, and the variation of Chl-a in spring is larger than that in summer and autumn. (3) River runoff and sea surface temperature will affect the variation of Chl-a, so the conc.