摘要
Chlorophyll a(Chl a)is a key photosynthetic pigment and an essential indicator of phytoplankton biomass.Accurate Chl a measurements are crucial for understanding marine biogeochemical processes.China launched the Chinese Ocean Color and Temperature Scanner(COCTS)aboard the HY-1D satellite in 2020,yet its Chl a products require further validation in complex coastal waters.This study assesses HY-1D Chl a products in the Bohai and Yellow Seas,two optically complex coastal regions,using in situ data collected during multiple cruises.Additionally,we compare HY-1D Chl a products with those from the Moderate Resolution Imaging Spectroradiometer(MODIS)and the Visible Infrared Imaging Radiometer Suite(VIIRS).We observed that although Chl a products from HY-1D are generally consistent with those from the MODIS and VIIRS in spatial distribution,there are still significant errors when compared with in situ data.Therefore,we developed a new blended algorithm to improve the accuracy of HY-1D Chl a products.The algorithm distinguishes between turbid and relatively clean waters using a classification index based on the ratio of remote sensing reflectance(R_(rs)(λ)).After the initial classification,we developed targeted algorithms based on the optical properties of different water bodies.The new model shows a significant improvement,reducing the mean absolute percentage error(MAPE)from 43.1%to 24.3%.Additionally,merging Chl a data from HY-1D,MODIS,and VIIRS maintains good accuracy,with HY-1D Chl a products significantly enhancing data coverage and robustness.This research provides important support for producing high-quality HY-1D Chl a products for coastal waters.
基金
The National Key Research and Development Program of China under contract No.2021YFB3901304
the National Natural Science Foundation of China under contract No.42842176181,42476173,and 42176179
the Natural Science Foundation of Jiangsu Province under contract No.BK20211289.
