Abstract: Monthly values for sea ice extent in the inner part of Kongsfjorden, Svalbard 2003-2019, as percentages of the total surface area during February-June each year. The data file has six columns: a) the year the data connects to, and b)-f) the numbers for maximum fast ice coverage (in percent from the defined observation area, equalling 120 km2) for each month from February to June (2003-2019) in the inner part of Kongsfjorden, derived from manually drawn and digitized ice maps (see above). This inner fjord area is based on a coastline from 1993. Since glaciers have been retreating since then, some new areas developed where there is a potential of sea ice formation. Those areas will be considered in future updates of the dataset. Gaps in some lines in the figure are related to years/months where no data are available. If an observation is missing, data is set to 999.
Land-fast sea ice covers the inner parts of Kongsfjorden, Svalbard, for a limited time in winter and spring months, being an important feature for the physical and biological fjord systems. Monitoring of the Kongsfjorden area has been carried out by the Norwegian Polar Institute (NPI) systematically since 2003 (Gerland and Renner 2007; Pavlova et al. 2019; Gerland et al. 2020). Conception and methodology of the systematic fast-ice monitoring in Kongsfjorden are described in Gerland and Hall (2006), Gerland and Renner (2007), and Pavlova et al. (2019) and include visual sea ice extent observations from the mountain Zeppelinfjellet (mapping) as well as in situ measurements of snow and ice thickness (Gerland and Renner 2007; Pavlova et al. 2019). The monitoring was designed to be relatively inexpensive, robust, and consistent over time. The permanent presence of NPI personnel at the Sverdrup unit in Ny-Ålesund Research Station and daily visits to the observatory on the mountain Zeppelinfjellet just south of Ny-Ålesund enable regular ice extent observations (weather, visibility, and daylight permitting).
Data collected within this standardized monitoring programme have contributed to a number of studies (see, e.g. Moe et al. 2012; Johansson et al. 2020). Monitoring of the sea-ice conditions in Kongsfjorden can be used to demonstrate and investigate phenomena related to climate change in the Arctic.