Sensitivity of Sea Ice Growth to Snow Properties in Opposing Regions of the Weddell Sea in Late Summer

• Published in: Geophysical Research Letters
• Main Author: Arndt, Stefanie
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: ddc:551.34; Antarctic; sea ice; snow; ice mass balance; thermal conductivity; ice growth; Southern Ocean; Weddell Sea; Weddell; Antarc*; Sea ice
• Online Access: https://doi.org/10.1029/2022GL099653; http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10451

The sensitivity of sea ice to the contrasting seasonal and perennial snow properties in the southeastern and northwestern Weddell Sea is not yet considered in sea ice model and satellite remote sensing applications. However, the analysis of physical snowpack properties in late summer in recent years reveals a high fraction of melt‐freeze forms resulting in significant higher snow densities in the northwestern than in the eastern Weddell Sea. The resulting lower thermal conductivity of the snowpack, which is only half of what has been previously assumed in models in the eastern Weddell Sea, reduces the sea ice bottom growth by 18 cm during winter. In the northwest, however, the potentially formed snow ice thickness of 22 cm at the snow/ice interface contributes to additional 7 cm of thermodynamic ice growth at the bottom. This sensitivity study emphasizes the enormous impact of unappreciated regional differences in snowpack properties on the thermodynamic ice growth. Plain Language Summary: The sea ice cover in the Weddell Sea shows different ice age classes and can therefore be considered as a representative basin of the ice‐covered Southern Ocean: while seasonal sea ice is found in the eastern Weddell Sea, it tends to be perennial in the west. Due to the year‐round Antarctic snow cover, this age classification also applies for the snow column. However, the associated regional differences in snow properties and snow‐to‐ice conversion processes at the snow/ice interface are not yet considered in both sea ice model and satellite remote sensing applications when retrieving, for example, sea ice thickness. Based on recent snow observations in the region, regionally adjusted values for snow density and thermal conductivity could be determined. While the adjusted parameters result in attenuated ice growth in the eastern Weddell Sea, significant snow ice formation causes additional thermodynamic ice growth in the western Weddell Sea. Key Points: High fraction of melt‐freeze forms causes significant higher snow ...