Estimating sea ice thickness using MODIS data: A case study in the Bohai Sea, China

In this paper, we present a direct approach to effectively estimate sea ice thickness over a large spatial area of the Bohai Sea using EOS MODIS data. It is based on the model of an exponential relationship between albedo and thickness of sea ice. 18 images of EOS MODIS L1B data in the 2009–2010 winter were used to estimate the sea ice thickness and to monitor its spatiotemporal evolutions in the Bohai Sea. The estimated thickness results are validated by using the Lebedev and Zubov models as well as the forecasting data from the National Marine Environmental Forecasting Centre of China. Model correlation coefficients (R²=0.84−0.85) and close similarity in thickness prediction attest to the reliability and applicability of the proposed method. The average ice thickness of the whole Bohai Sea ranged from 3 to 21 cm, and the estimated maximum was about 40 cm in Liaodong Bay. Multiple-temporal maps of sea-ice thickness show that the sea ice first formed along the coastline, and gradually expanded away from the shore. Sea ice first appeared in the Liaodong Bay, and hugged the coast southwards to Bohai and Laizhou Bay. Our results also show that sea ice extent and thickness are significantly correlated with the value of θ, the difference between cumulative FDD (Freezing Degree Days) and TDD (Thawing Degree Days).