The presence of sea-ice leads represents a key feature of the Arctic sea ice cover. Leads promote the flux of sensible and latent heat from the ocean to the cold winter atmosphere and are thereby crucial for air-sea-ice-ocean interactions. We here apply a binary segmentation procedure to identify leads from MODIS thermal infrared imagery on a daily time scale. The method separates identified leads into two uncertainty categories, with the high uncertainty being attributed to artifacts that arise from warm signatures of unrecognized clouds. Based on the obtained lead detections, we compute quasi-daily pan-Arctic lead maps for the months of January to April, 2003–2015. Our results highlight the marginal ice zone in the Fram Strait and Barents Sea as the primary region for lead activity. The spatial distribution of the average pan-Arctic lead frequencies reveals, moreover, distinct patterns of predominant fracture zones in the Beaufort Sea and along the shelf-breaks, mainly in the Siberian sector of the Arctic Ocean as well as the well-known polynya and fast-ice locations. Additionally, a substantial inter-annual variability of lead occurrences in the Arctic is indicated.

Please note: A new version of this data set featuring improved lead detection, spatial resolution and ESPG:3413 grid is available (Reiser et al., 2020, doi:10.3390/rs12121957). The daily data is published in Willmes et al. (2023).We here present quasi-daily pan-Arctic lead maps for the months of January to April from 2003 to 2015 at a spatial resolution of less than 2 km². This data set can be used to deduct the occurrence, structure and dynamics of wintertime sea-ice leads and to assess seasonal divergence patterns of the Arctic Ocean.The daily maps are provided in one NetCDF file for each year. Each maps contains 5 categories, indicated by different numbers: 0: land mask, 1: no data (cloud or open ocean), 2: sea ice, 3: artifact (high uncertainty) and 4: lead. A latitude/longitude map is provided in a separate NetCDF file.

Supplement to: Willmes, Sascha; Heinemann, Günther (2015): Sea-Ice Wintertime Lead Frequencies and Regional Characteristics in the Arctic, 2003–2015. Remote Sensing, 8(1), 4