Evaluation of Four Satellite-Derived High-Resolution Operational Sea Ice Concentration Products for Determination of Marginal Ice Zones Around Svalbard

Marginal ice zone (MIZ) is a transitional region between dense pack ice and open water. It is a highly dynamic zone under strong interactions among the atmosphere, ocean, sea ice and waves, playing a crucial role in the polar climate system and ecosystem. Accurate determination of MIZ is, therefore, essential for advancing our understanding, modeling and prediction of the polar climate system and ecosystem. In this paper, we introduce and apply a comprehensive suite of MIZ-related metrics to evaluate the performance of four satellite-derived high-resolution operational sea ice concentration (SIC) products in characterizing the MIZs around Svalbard, using the Norwegian ice chart as reference. The metrics used for evaluation include sea ice extent (SIE), MIZ extent (MIZE), MIZ position, MIZ width, length of ice edge (LIE), integrated ice edge error (IIEE), integrated MIZ error (IME), ice edge distance error (IEDE), and MIZ width error (MWE). The evaluation is based on two years of daily SIC data (2024–2025) from four products, including the Bremen AMSR2 SIC data from the University of Bremen (Bremen SIC), the resolution-enhanced AMSR2 SIC (RE SIC) and Multisensor SIC products (Multisensor SIC) from the Norwegian Meteorological Institute, and the Automated Sea Ice Product (ASIP) from the Copernicus Marine Environment and Monitoring Service (CMEMS) (ASIP SIC). To be consistent with the Norwegian ice chart, the MIZ is defined as MIZ70 and MIZ90, corresponding to SIC thresholds of up to 0.7 and 0.9, respectively. The evaluation results demonstrate that all four satellite SIC products generally capture the evolution of the sea ice conditions around Svalbard well, but differ in their accuracies in characterizng the sea ice edge and MIZs. On the whole, the ASIP product agrees best with the ice chart in describing the sea ice edge and MIZ70 through a large number of metrics, in particular the primary metrics IIEE and IME70. The Bremen SIC product tends to overlook areas with low SIC, leading to a significant underestimate of SIE and a large IIEE. However, it provides an overall close agreement with the ice chart in the MIZE90. The RE SIC product exhibits good performance in capturing the SIE, but tends to notably overestimate the MIZE. Multisensor provides the closest agreement with the ice chart for the IME90, MWE90 and MWEa70, and ranks as the second-best product for the IIEE, IME70 and MWEr70. Our results suggest that SAR and low-frequency AMSR2 channels are especially effective for determining the lower bound of the MIZ, while high-frequency AMSR2 channels are more suitable for detecting the upper bound. In addition, the complex summer surface conditions pose significant challenges for satellite sensors in determining the ice edge and MIZ, resulting in large IEDE and MWE during this period. The results highlight both the capabilities and limitations of satellite-based data in characterizing the MIZ, particularly under the challenging summer conditions. Accurate delineation of MIZs may require significant advancements in satellite observation technologies, retrieval algorithms, and more robust methods for integrating multiple sources.