Impact of Atlantic water variability on sea ice changes in the Fram Strait and north of Svalbard

Recent satellite passive microwave observations indicate significant negative Arctic sea ice extent trends in all months and substantial reduction of winter sea ice in the Atlantic sector. Warm and salty oceanic water masses from the North Atlantic flow towards the Arctic Ocean along the eastern Fram Strait, carried by the West Spitsbergen Current (WSC). Fram Strait, as well as the region north of Svalbard, play a key role in controlling the amount of oceanic heat supplied to the Arctic Ocean and are the place of dynamic interaction between the ocean and sea ice. The north of Svalbard area is one of the regions where the substantial changes in sea ice concentrations are observed both in summer and in winter. One of the possible reasons can be sought in the observed warming of Atlantic water, carried through Fram Strait into the Arctic Ocean. The main goal of this work is to analyse and explain the sea ice variability along main pathways of the Atlantic origin water (AW) in the context of observed warming of Atlantic water layer. Shrinking sea ice cover in the southern part of Nansen Basin (north of Svalbard) and shifting the ice edge in Fram Strait are driven by the interplay between increased advection of oceanic heat in the Atlantic origin water and changes in the local atmospheric conditions that result in the increased ocean-air-sea ice exchange in winter seasons. The basis for this hypothesis is warming of winter mean surface air temperature observed north of Svalbard and withdrawal of the sea ice cover towards the northeast, along with the pathways of water inflow in the Atlantic sector of the Arctic Ocean. Hydrographic data from vertical CTD profiles were collected during annual summer expeditions of the research vessel "Oceania", conducted in Fram Strait and the southern part of the Nansen Basin over the past two decades. The measurement strategy of the original research program AREX, which consists of the performance of cross-sections perpendicular to the presumed direction of the West Spitsbergen Current, allowed to observe changes in the properties and transport of the Atlantic Water carried to the Arctic Ocean. The analysis of past and present changes in the sea ice cover in relation to Atlantic water variability and atmospheric forcing employs hydrographic data from the repeated CTD sections, systematically collected since 1996 during annual summer Arctic long-term monitoring program AREX, satellite products of sea ice concentration and drift, and selected reanalysis data sets.