Daily Arctic polynya masks 1978-2024 from two satellite sea ice products (SMMR, SSM/I & SSMIS and SMOS & SMOS-SMAP)

This dataset provides four daily Arctic polynya masks derived from two satellite sea ice products. The products used are (1) the daily sea ice concentration (SIC) dataset from the National Snow and Ice Data Center (DiGirolamo et al., 2022; for years 1978–2024) and (2) the daily thin ice thickness (SIT) dataset from the University of Bremen Sea Ice Remote Sensing Group (SMOS and SMOS/SMAP Thin Ice Thickness, Huntemann et al., 2014 and Paţilea et al., 2019; for years 2012–2024). The study region covers the Arctic Ocean 65° - 90°N. Two wintertime study periods are included, corresponding to two research articles (Wong, C H M et al., 2026; Heuzé, C & Wong, C H M, in 2025). Polynya thresholds are defined as 50% for SIC and 20 cm for SIT. Details of the full polynya detection method are provided in Wong, C H M et al. (2026).