Thermodynamic Sea Ice Growth in Arctic Fjords

摘要

Arctic fjords are usually covered by seasonal landfast ice during winter and spring months. Sea ice growth in the fjords is affected by the local atmospheric and oceanic conditions, which can differ considerably. In this study, we focus on the thermodynamic growth of sea ice in two fjords in the Svalbard Archipelago, Kongsfjorden and Rijpfjorden. They are located on the northwest coast of Spitsbergen and on the north coast of Nordaustlandet, northeast of Spitsbergen, respectively. In Kongsfjorden, sea ice usually forms between December and February, and persists until end of May or early June. Sea ice formation is influenced by warm Atlantic water, reaching the fjord through the West Spitsbergen Current. Systematic sea ice monitoring was started by the Norwegian Polar Institute (NPI) in 2003. Fast ice in Kongsfjorden develops mainly in its innermost part. Rijpfjorden is characterized by cold Arctic water masses. Sea ice usually forms between October and January, and breaks up between mid-July and mid-August. After ice breakup, drift ice can fill up this fjord during summer under the effect of northerly winds. Sea ice data was collected on fast ice in Rijpfjorden continuously with an ice mass balance (IMB) buoy and during three visits by manual measurements along a 50 m baseline near the IMB site between April and June 2011. The collected data in the two fjords shows that a secondary ice type formed-at the snow-ice interface (snow ice or superimposed ice) contributes to the sea ice growth in both Kongsfjorden and Rijpfjorden. A one-dimensional thermodynamic sea ice model, which takes into account snow ice and superimposed ice formation, is used to investigate the ford's sea ice evolution.