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Inversion of Sea Ice Concentration in the Liaodong Bay from MODIS Data

Sea ice concentration is an important observation element and a necessary input parameter for the numerical prediction of sea ice. In this study, a new method is developed for the inversion of sea ice concentration (SIC) in Liaodong Bay from MODIS data based on the Normalized Difference Water Index (NDWI). By comparing the inverted results of the NDWI method and the WU’s methods, as well as observations from six shore-based observation points on the east coast of Liaodong Bay in the winter of 2016/2017 and Landsat 8 OLI data, the method based on NDWI is shown to be a useful tool to estimate the SIC. The SIC obtained by the NDWI method is in good agreement with the survey data. The mean absolute error between the SIC obtained by the NDWI method and visual observation is about 10%. In the comparison data, 92% of the absolute error values of SIC are less than 20%. The average value of the error of the SIC obtained by the NDWI method is 1%, and that of the WU’s method is about −10%, which means the accuracy of SIC obtained by the NDWI method is better. The mean deviation of the error of the SIC obtained by the NDWI method and the WU’s method is about 9% and 13%, which shows a certain improvement in precision. The validation results with the Landsat 8 OLI data show the precision of the SIC obtained by the NDWI method is better than the WU’s method, which is consistent with the validation result of the survey data.