After a long-term, slightly positive trend in sea ice extent (SIE), the Antarctic SIE has undergone an unprecedented decline, with record-low values being broken several times since 2016. As a topic of ongoing research, several studies have attributed this decline to a combination of atmospheric and oceanic factors, such as upper-ocean warming and the advection of warm, moist air into the region.
Sea ice plays a critical role in the climate system by enhancing the region’s albedo and limiting direct fluxes between the ocean and the atmosphere. Conversely, reduced SIE exposes larger areas of open ocean, potentially enhancing heat and moisture fluxes into the atmosphere. This moistening and warming of the atmosphere, in turn, could alter snowfall patterns through enhancement of available atmospheric moisture and energy fluxes towards the snow-ice interface, promoting internal snowmelt and the formation of superimposed ice via meltwater percolation and refreezing.
Although studies suggest that the coupled ocean-atmosphere-ice system is undergoing significant changes under current conditions, the implications and the proposed feedback for snow and ice properties remain unclear. This study addresses this gap by investigating the sensitivity of snowfall and superimposed ice formation to atmospheric influences in recent years of low SIE in the Weddell Sea, Antarctic. The Weddell Sea, characterised by both seasonal and perennial sea ice, has been identified as a key contributor to the Antarctic SIE decline.
This study explores the connection between increased open ocean areas (due to low SIE) and changes in snowfall and superimposed ice formation. I test the hypothesis that proximity to the ice edge significantly influences atmospheric conditions over the ice by correlating snow and ice variables with distance to the open ocean. Furthermore, the study aims to shed light on potential changes in these variables by comparing recent years (2016-2023) with a 30-year reference period (1980-2009).
Results indicate no definitive linear relationship between snowfall and distance to the ice edge, suggesting that larger-scale atmospheric circulations play a dominant role. Conversely, superimposed ice formation shows a clear relationship with proximity to the open ocean, with higher surface energy balance (SEB) values and increased occurrence closer to open water. While a comparison between recent years and the reference period reveals no significant changes in the SEB or potential superimposed ice formation, the spatial extent of zones exhibiting a strong SEB-distance relationship has expanded in recent years compared to years with similar SIE in the reference period. This suggests a shift in the area where superimposed ice formation is most likely to occur, potentially driven by changes in sea ice concentration or atmospheric conditions.
Meanwhile, snowfall in recent years shows periods of increased magnitudes, accompanied by higher wind speeds and atmospheric moisture, hinting at a change in ocean-atmosphere interactions. These changes have critical implications for the sea ice environment, potentially altering albedo, insulation through snow cover thickness, and the ice mass balance through snow-ice conversion.
The findings provide insights into the spatial patterns and potential changes of snowfall and superimposed ice formation in recent years and their complex interactions. They also highlight the need for further research in this area, particularly given their critical role in modulating sea ice mass balance and ice-albedo feedback, thereby influencing the broader climate.