Chinese Journal of Polar Research

Chinese Journal of Polar Research ›› 2025, Vol. 37 ›› Issue (4): 681-701.DOI: 10.13679/j.jdyj.20240058

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Uncertainty assessment of Arctic sea ice lead products based on MODIS thermal infrared data

WENG Zhilong1, LIU Yan1, JIA Peng1, WANG Caihong1, CHENG Xiao2,3,4, CHEN Zhuoqi2,3,4   

  1. 1 State Key Laboratory of Remote Sensing Science, Faculty of Geographical Sciences, Beijing Normal University, Beijing 100875, China;
    2 School of Geomatics Science and Technology, Sun Yat-sen University, Zhuhai 519082, China;
    3 Guangdong Laboratory of Southern Marine Science and Engineering (Zhuhai), Zhuhai 519082, China;
    4 Polar Joint Research Center of Chinese Universities, Beijing 100875, China
  • Received:2024-05-30 Revised:2024-09-02 Online:2025-12-30 Published:2026-01-12

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Abstract: Monitoring the spatial and temporal distribution of Arctic sea ice is important for improving our understanding of oceanic heat flux and sea-air mass exchange in the polar regions and for supporting the potential opening of Arctic shipping routes. Moderate resolution imaging spectroradiometer (MODIS) thermal infrared data, characterized by high spatial and temporal resolution and large coverage, are widely used to identify leads (ice-free waterways) in sea ice. However, there are significant discrepancies and uncertainties in the different products. This paper compares and evaluates the accuracy of three major thermal infrared lead products (the Willmes, Reiser, and Hoffman products, respectively) and analyzes lead extraction uncertainties and their sources. The results show that there are significant discrepancies between the daily lead areas in the three products, with the Willmes, Hoffman, and Reiser products extracting 53.1%, 106.0%, and 140.8% of the daily average lead area, respectively. There are three main sources of uncertainty in lead extraction: (1) narrow leads are inadequately extracted, resulting in misclassification rates exceeding 50% in all three products. (2) All three products are daily synthesis products that are based on the multiperiod thermal infrared data of a single day. Because of sea ice drift, the same lead is extracted repeatedly at different locations, resulting in overestimation of the width and area of rapidly drifting leads. (3) The Willmes and Reiser products are designed with a fuzzy cloud artifact filter (FCAF) to mitigate the effects of clouds and other high-temperature features on the extraction of ice-covered waterways. However, the different FCAF algorithms result in significant discrepancies in the extraction of the extent of ice-covered waterways. The results of this study can serve as a reference for the use of lead products in a variety of applications.

Key words: sea ice lead, moderate resolution imaging spectroradiometer (MODIS), thermal infrared, uncertainty, Arctic