Comparison between AMSR2 Sea Ice Concentration Products and Pseudo-Ship Observations of the Arctic and Antarctic Sea Ice Edge on Cloud-Free Days

In recent years, much attention has been paid to the behavior of passive microwave sea ice concentration (SIC) products for marginal ice zones. Based on the definition of ice edges from ship observations, we identified pseudo-ship observations (PSO) and generated PSO ice edges from twelve cloud-free moderate-resolution imaging spectroradiometer (MODIS) images. Two SIC products of the advanced microwave scanning radiometer 2 (AMSR2) were compared at the PSO ice edges: ARTIST (arctic radiation and turbulence interaction study) sea ice (ASI-SIC) and bootstrap (BST-SIC). The mean values of ASI-SIC pixels located at ice edges were 10.5% and 10.3% for the Arctic and the Antarctic, respectively, and are below the commonly applied 15% threshold, whereas the mean values of corresponding BST-SIC pixels were 23.6% and 27.3%, respectively. The mean values of both ASI-SIC and BST-SIC were lower in summer than in winter. The spatial gaps among the 15% ASI-SIC ice edge, the 15% BST-SIC ice edge and the PSO ice edge were mostly within 35 km, whereas the 15% ASI-SIC ice edge matched better with the PSO ice edge. Results also show that the ice edges were located in the thin ice region, with a mean ice thickness of around 5–8 cm. We conclude that the 15% threshold well determines the ice edge from passive microwave SIC in both the Arctic and the Antarctic

Measurement, Knowledge, and Representation: A Sociological Study of Arctic Sea-Ice Science

Satellite-derived observations of Arctic sea ice are instrumental in contemporary sea-ice research. Through the production and dissemination of data products, these observations shape our understanding of Arctic sea-ice conditions, knowledge of which is essential for informing policy responses, decision-making, and action in the face of unprecedented climate change. However, due to the complex, dynamic, and indeterminate nature of sea ice and various scientific and technological challenges involved in its observation, measurement, and representation, the accuracy to which these products depict Arctic sea ice is limited. Moreover, the methodologies used to acquire, process, and report satellite data vary between scientific institutions, resulting in inconsistent estimates of key sea-ice parameters. Informed by social constructivist arguments developed within science and technology studies and critical cartography, this thesis contends that satellite-derived sea-ice data products represent a particular way of observing, interpreting, and classifying complex geophysical conditions that is socially and culturally contingent. This raises important questions about how sea-ice knowledge is constructed through the interactions between sea ice, sensing technologies, and social practices. Accordingly, this thesis integrates ethnographic and visual methodologies to critically explore how dynamic and indeterminate geophysical data are acquired, processed, and reported in Arctic sea-ice science. By examining sea-ice data products in terms of their underlying practices and technologies, institutional settings, and the broader socio-cultural, political, and historical contexts in which they are embedded, this thesis provides insights into the sociological nature of contemporary sea-ice research. It concludes that greater recognition of the social contingencies shaping how sea-ice data products are generated and disseminated is needed to foster more democratic and socially responsible forms of scientific knowledge. The findings presented in this thesis may provide valuable starting points for critically examining how sea-ice science may be made more equitable and enriched or improved by alternative perspectives