Steady increase in water clarity in Jiaozhou Bay in the Yellow Sea from 2000 to 2018: Observations from MODIS

Abstract

The Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data were used to analyze the temporal and spatial distribution characteristics of water clarity (Zsd) in the Jiaozhou Bay, Qingdao, China, in the Yellow Sea from 2000 to 2018. Zsd retrieval models were regionally optimized using in-situ data with coincident MODIS images, and then were used to retrieve the Zsd products in Jiaozhou Bay from 2000–2018. The analysis of the Zsd results suggests that the spatial distribution of relative Zsd spatial characteristics in Jiaozhou Bay was stable, being higher Zsd in the southeast and a lower Zsd in the northwest. The annual mean Zsd in Jiaozhou Bay showed a significant upward trend, with an annual increase of approximately 0.02 m. Water depth and wind speed were important factors affecting the spatial distribution and annual variation of Zsd in Jiaozhou Bay, respectively.