Extent, duration and timing of the sea ice cover in Hornsund, Svalbard in 2014–2023

• Main Authors: Swirad, Zuzanna M., Johansson, A. Malin, Malnes, Eirik
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Svalbard; Hornsund; The Sentinel; Brepollen; Burgerbukta; Samarinvågen; Sea ice
• Online Access: https://doi.org/10.5194/egusphere-2023-2592; https://noa.gwlb.de/receive/cop_mods_00070509; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068857/egusphere-2023-2592.pdf; https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2592/egusphere-2023-2592.pdf

The Sentinel-1A/B synthetic aperture radar (SAR) imagery archive between 14 October 2014 and 29 June 2023 was used in combination with a segmentation algorithm to create a series of binary ice/open water maps of Hornsund fjord, Svalbard at 50 m resolution for nine seasons (2014/15 to 2022/23). The near-daily (1.57 day mean temporal resolution) maps were used to calculate sea ice coverage for the entire fjord and its parts: the main basin and three major bays: Burgerbukta, Brepollen and Samarinvågen. The average length of the sea ice season was 158 days (range: 105–246 days). Drift ice first arrived from the south-west between October and March and the fast ice onset was on average 24 days later. The fast ice typically disappeared in June, around 20 days after the last day with drift ice. The average sea ice coverage over the sea ice season was 41 % (range: 23–56 %), but it was lower in the main basin (27 %) compared to the bays (63 %). Of the bays, Samarinvågen had the highest sea ice coverage (69 %) likely due to the location in southern Hornsund protected from the incoming wind-generated waves and a narrow opening. Seasonally, the highest sea ice coverage was observed in April for the entire fjord and the bays, and in March for the main basin. The highest sea ice coverage characterised 2019/20, 2021/22 and 2014/15, which were also the seasons with the largest number of negative air temperature days in October – December. The season 2019/20 was characterised by the lowest mean daily and monthly air temperatures. We observed a remarkable inter-annual variability in the sea ice coverage but at the nine-season scale we did not record any gradual trend of decreasing sea ice coverage. These high-resolution data can be used to e.g., better understand the spatio-temporal trends in the sea ice distribution in Hornsund, facilitate comparison between Svalbard fjords and improve modelling of nearshore wind wave transformation and coastal erosion.