Physics-based SNOWPACK model improves representation of near-surface Antarctic snow and firn density

• Published in: The Cryosphere
• Main Authors: E. Keenan, N. Wever, M. Dattler, J. T. M. Lenaerts, B. Medley, P. Kuipers Munneke, C. Reijmer
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental sciences; GE1-350; Geology; QE1-996.5; Antarctic; The Antarctic; Antarc*; Ice Sheet; The Cryosphere
• Online Access: https://doi.org/10.5194/tc-15-1065-2021; https://doaj.org/article/94c255278a7f4a2d81115b6774e50c0b

Estimates of snow and firn density are required for satellite-altimetry-based retrievals of ice sheet mass balance that rely on volume-to-mass conversions. Therefore, biases and errors in presently used density models confound assessments of ice sheet mass balance and by extension ice sheet contribution to sea level rise. Despite this importance, most contemporary firn densification models rely on simplified semi-empirical methods, which are partially reflected by significant modeled density errors when compared to observations. In this study, we present a new drifting-snow compaction scheme that we have implemented into SNOWPACK, a physics-based land surface snow model. We show that our new scheme improves existing versions of SNOWPACK by increasing simulated near-surface (defined as the top 10 m ) density to be more in line with observations (near-surface bias reduction from − 44.9 to − 5.4 kg m −3 ). Furthermore, we demonstrate high-quality simulation of near-surface Antarctic snow and firn density at 122 observed density profiles across the Antarctic ice sheet, as indicated by reduced model biases throughout most of the near-surface firn column when compared to two semi-empirical firn densification models (SNOWPACK <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>mean bias</mtext><mo>=</mo><mo>-</mo><mn mathvariant="normal">9.7</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="88pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="d4563868c957e632f059fa36e2231f24"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-15-1065-2021-ie00001.svg" width="88pt" height="10pt" src="tc-15-1065-2021-ie00001.png"/></svg:svg> kg m −3 , IMAU-FDM <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>mean ...