The effects of snow and salt on ice table stability in University Valley, Antarctica

• Published in: Antarctic Science
• Main Authors: Williams, K.E., Heldmann, J.L., McKay, Christopher P., Mellon, Michael T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2017
• Subjects: Geology; Ecology, Evolution, Behavior and Systematics; Oceanography; Antarctic; The Antarctic; University Valley; Antarc*; Antarctic Science; Antarctica; Ice; permafrost
• Online Access: http://dx.doi.org/10.1017/s0954102017000402; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102017000402

Abstract The Antarctic Dry Valleys represent a unique environment where it is possible to study dry permafrost overlaying an ice-rich permafrost. In this paper, two opposing mechanisms for ice table stability in University Valley are addressed: i) diffusive recharge via thin seasonal snow deposits and ii) desiccation via salt deposits in the upper soil column. A high-resolution time-marching soil and snow model was constructed and applied to University Valley, driven by meteorological station atmospheric measurements. It was found that periodic thin surficial snow deposits (observed in University Valley) are capable of drastically slowing (if not completely eliminating) the underlying ice table ablation. The effects of NaCl, CaCl 2 and perchlorate deposits were then modelled. Unlike the snow cover, however, the presence of salt in the soil surface (but no periodic snow) results in a slight increase in the ice table recession rate, due to the hygroscopic effects of salt sequestering vapour from the ice table below. Near-surface pore ice frequently forms when large amounts of salt are present in the soil due to the suppression of the saturation vapour pressure. Implications for Mars high latitudes are discussed.