Accuracy Assessment Of Sea Ice Concentration And Extent Products In The Marginal Ice Zone

Sea ice is an important component of the cryosphere,which can significantly affect the global ocean and atmosphere through the exchange of heat and mass between the oceans and the atmosphere.The marginal ice zone is a buffer zone for open water and pack ice.Accurately determining the sea ice edge in the marginal ice zone is an essential prerequisite for estimating the change trend of sea ice extent and area in the Arctic.Passive microwave sea ice concentration products are the main data sources used to analyze the range and area changes of long-term serial sea ice.However,they have low resolutions and different sensors or algorithms,that receive different results.Therefore,the accuracy of sea ice concentration products at sea ice edge should be verified.With regard to verification data,there are ship navigation observation data,optical image data,and SAR image data,and there are differences in the accuracy of different data and the difficulty of data acquisition.The 15%threshold is an internationally recognized threshold for dividing the ice edge of passive microwave sea ice concentration products,but the problem is that the 15%threshold is too simple to classify.Therefore,high-resolution images are needed to extract the sea ice edge and confirm the rationality of the 15%threshold.Based on the ASPeCt ship observation rule,this paper extracts the simulated ship's sea ice edge on the MODIS image,and compares the edges of the AMSI2 ASI and BST sea ice concentration products with them.Then add the SMOS sea ice thickness data,US National Ice Center ice product,Radarsat2 image and OSI-SAF sea ice edge product for analysis.The research results of this paper are divided into the following aspects:(1)The average sea ice concentration of the ASI at the sea ice edge in Arctic and Antarctic is 10.5%and 10.3%,respectively.The average sea ice concentration of the ASI at the sea ice edge in Arctic and Antarctic is 23.6%and 27.3%,respectively.And the average sea ice concentration of both ASI and BST was lower in summer than in winter.ASI will underestimate the sea ice concentration compared with the pseudo ship observation,while BST will overestimate sea ice concentration.The average sea ice thickness at the three sea ice edges was compared and the mean sea ice thickness at the 15%ASI sea ice edge,the 15%BST sea ice edge and the pseudo ship observation was found to be 8.0cm,5.3 cm and 6.6cm respectively.(2)NIC ice chart will overestimate the sea ice concentration,tend to determine the diffuse sea ice to open water,such as in the optical and SAR images.The differences of NIC ice edge and ASI ice edge are greater in summer than winter(up to 50km).(3)The sea ice edge of the OSI-SAF is similar to the sea ice edge determined by the pseudo ice edge and passive microwave sea ice products in most cases.It is generally located at the middle of 15%ASI sea ice concentration edge and 15%BST sea ice concentration edge.However,the OSI-SAF sea ice edge at the diffuse sea ice edge tend to underestimate the sea ice concentration and therefore the sea ice edge of it is close to the sea ice side.In sum,compared with pseudo sea ice edge,AMSR2 ASI underestimate sea ice concentration,BST overestimate it,NIC ice chart much overestimate it and OSI-SAF underestimate it.