Attributing near-surface atmospheric trends in the Fram Strait region to regional sea ice conditions

• Main Authors: Schmitt, Amelie U., Lüpkes, Christof
• Format: Text
• Language: English
• Published: 2022
• Subjects: Arctic; Greenland; Merra; Fram Strait; Greenland Sea; Nansen Basin; Sea ice
• Online Access: https://doi.org/10.5194/tc-2022-185; https://tc.copernicus.org/preprints/tc-2022-185/

Arctic sea ice has declined in all seasons accompanied by a rapid atmospheric warming. Here, the focus lies on the wider Fram Strait region where the connection between trends in observed near-surface variables (temperature, humidity, wind speed) and local sea ice conditions are analyzed. Reanalysis data from ERA5 and MERRA-2 for the winters 1992 to 2022 are used for the analyses. To disentangle the impact of the upstream sea ice conditions from other factors influencing atmospheric conditions, separate calculations are applied for on-ice and off-ice flow. During off-ice flow, temperatures increased by more than 9 K within 31 years in the Western Nansen Basin (WNB) and by about 5 K in the Greenland Sea region (GRL). Humidity also increased significantly in both regions but with smaller trends in the GRL region. Trends for wind speed were mostly not significant. Corresponding trends of winter sea ice concentrations based on SSM/I-ASI data show a decrease of -10 % dec −1 in the WNB region with especially large open water areas in 2022. There are clear hints that sea ice variability in the GRL region is strongly influenced by the presence of the Odden ice tongue and thus it shows a decrease of -4.7 % dec −1 . For off-ice flow, upstream sea ice conditions in the Fram Strait region influence atmospheric temperatures and humidity up to 500 km downstream of the ice edge. Up to two thirds of the observed temperature variability in both regions can be explained by upstream sea ice variability, which is about 10 % more than for all other wind directions.