Abstract: Sea ice concentration is an important parameter to describe the characteristics of sea ice. It is of great significance to obtain accurate sea ice concentration for the study of global climate change. In this study, we improves the atmospheric correction effect of summer observed brightness temperature by optimizing the estimation of sea ice emissivity and initial sea ice concentration in the microwave radiative transfer model, thereby optimizing the retrieval results of sea ice concentration using passive microwaves. Based on the FY-3D/MWRI brightness temperature data from June to September 2019, four sets of Arctic sea ice concentration data (ASI2-FTP, ASI2-DTP, ASI2E-FTP, ASI2E-DTP) were obtained by using the original and enhanced ASI2 algorithm (ASI2 and ASI2E) combined with fixed tie points and dynamic tie points (FTP and DTP). The results were evaluated by 14 MODIS images. The enhanced method can effectively improve the Arctic sea ice concentration retrieval in summer, which is particularly effective for the method based on fixed tie points. After enhancement, the root mean square error decreased from 21.9 % to 15.43 %, and the bias reduced from –12.40 % to –6.01 %. Among the four methods, the enhanced algorithm based on dynamic tie points (ASI2E-DTP) performs best, with a root mean square error of 14.33 % and a bias of –4.53 %.

Key words: sea ice concentration, ASI2 algorithm, FY-3D/MWRI, atmospheric correction, Arctic