| 31 Aug 2026
Community Challenge for Image-Derived Observation of Sea Ice Drift and Deformation
Abstract. Ongoing and unprecedented Arctic sea ice changes impact Arctic life, industry, and the environment. The sea ice cover is becoming younger, thinner, less expansive, and more dynamic; important changes we do not fully understand. Measuring sea ice motion with high fidelity, over large areas and long timescales, is needed to assess how ice dynamics are evolving. Addressing key hypotheses about ice dynamics will improve predictions of Arctic sea ice and climate change and enable developing strategies to adapt to and mitigate adverse effects of sea ice loss. Therefore, we seek to accelerate the development of tools that measure sea ice motion and deformation.
Current tools for extracting sea ice motion from remote sensing imagery produce motion fields too coarse in resolution to resolve individual floes and fractures and have a limited ability to resolve certain types of motion such as floe rotation. Addressing these shortcomings by deploying higher fidelity motion analysis over large areas and at high cadence, is needed to test hypotheses about the effect of small scale fracture mechanics on larger scale motion. We aim to focus such efforts by creating a “community challenge problem” against which methods can be tested. We release a dataset that includes all necessary input imagery and a standardized validation process using ground truth motion derived from extensive drifting buoy networks. The problem is documented in a manner designed to enable contributions to the challenge from outside the core sea ice community.
This paper presents a data set of buoy-derived sea ice drift and a collection of SAR image pairs over two recent highly sampled sea ice drift experiments, MOSAiC and SIDEx. It further poses a challenge to the community to test sea ice motion algorithms with the data set and report in the literature with a set of evaluation metrics the authors propose as a standard. The open access data and recommended evaluation metrics are intended to make evaluations of sea ice motion and deformation methodologies easier to compare against the provided high-fidelity buoy drift measurements to spur faster development of tools and models.
While the paper describes a data set that would be appropriate for a data journal, I think the paper is very appropriate for the audience of The Cryosphere. The purpose of this paper is well articulated and the methods are sound. I recommend several minor revisions to improve clarity prior to publication. These are mostly to clean up the text, figure labels, and in text references to the correct figures and equations.
Minor Comments
The descriptions of the MOSAiC and SIDEx time periods and locations (lat/lon ranges) are inconsistent between Sections 2.1 (L196-220) and 2.2 (L274-291). Make these descriptions consistent throughout the paper. The text describing the four drift periods is quite repetitive in these two sections. Revise. A pan-Arctic map showing a labeled box for each of the four drift periods would be helpful, perhaps as another panel on Fig.1. Reference to this panel could be used in Section 2.1 to reduce some of the duplication of the descriptions. Save the specific descriptions for Section 2.2.
Having looked at the supplemental buoy files, there are headers in the .csv files that are not shown in Table 1 (lat_i_r, lat_f_r, a, 1_a, c). These require more documentation or removal from the data files if irrelevant.
The equations are sort of dropped into the text rather than being incorporated into the discussion. Many of them also lack sufficient description of all the terms (e.g., L489-493). I recommend integrating the equation and description of terms into the paragraphs to help better explain the purpose of each equation.
Figure 1 and caption have some labeling issues. The bottom panel is showing a SAR image for 2 June, but the label reads July 1-7 Motion. There are no panel labels as indicated in the caption. I recommend adding a graticule with lat and lon labels to the figures showing SAR images and drift tracks for reference, especially Figs. 1 and 2.
Figures 4 and 6 describe parts 1 and 3 of the challenge workflow. Presumably there is a part 2 that is not described in the paper the same way. I suggest revising the flowchart figures and text to resolve this. Maybe use a short descriptive name instead of parts.
Technical Comments
L165: throughput considerations?
There are no in text references to see figs. 1, 6, 7, 10 and eq. 10.
L196-197: The phrasing here is confusing. I suggest: “…observation periods: 2-17 January 2020, 1-20 June 2020, and 1-7 July 2020.”
L199: “in the East Siberian Sea” is wrong here. Either delete or change to central Arctic.
L207: typo? -82N, also use degree symbol for your coordinates throughout.
L255: Are these numbered references? Fix.
L340: define L1-GRD here at first use, instead of at L353.
L412: Is the superscript another reference?
L434: A parenthesis is missing.
L522: Figure 8. Delete “a”.
L555: I suggest replacing the “/” with “and” and adding “, respectively” to the end of the sentence to improve clarity.
L559: I think the quotation marks are unnecessary. The text makes it very clear what you mean by submission.
L570: Typo – Figure 10
L587-588: BEAM-DIMAP are not expanded or explained in the text.