Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2016-155
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
29 Jun 2016
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal The Cryosphere (TC).
Surface formation, preservation, and history of low-porosity crusts at the WAIS Divide site, West Antarctica
John M. Fegyveresi1,2, Richard B. Alley2, Atsuhiro Muto3, Anaïs J. Orsi4, and Matthew K. Spencer5 1Terrestrial and Cryospheric Sciences Branch, US Cold Regions Research and Engineering Laboratory (CRREL), Hanover, NH, 03755, USA
2Dept. of Geosciences, and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, 16802, USA
3Dept. of Earth and Environmental Science, College of Science and Technology, Temple University, Philadelphia, PA, 19122, USA
4Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191, Gif-sur-Yvette, France
5School of Physical Sciences, Lake Superior State University, Sault Sainte Marie, MI, 49783, USA
Abstract. Observations at the WAIS Divide site show that near-surface snow is strongly altered by weather-related processes such as strong winds and temperature fluctuations, producing features that are recognizable in the deep ice core. Prominent "glazed" surface crusts develop frequently at the site during summer seasons. Surface, snow pit, and ice core observations made in this study during summer field seasons from 2008–09 to 2012–13, supplemented by Automated Weather Station (AWS) data with insolation sensors, revealed that such crusts formed during relatively low-wind, low-humidity, clear-sky periods with intense daytime sunshine. After formation, such glazed surfaces typically developed cracks in a polygonal pattern with few-meter spacing, likely from thermal contraction at night. Cracking was commonest when several clear days occurred in succession, and was generally followed by surface hoar growth; vapor escaping through the cracks during sunny days may have contributed to the high humidity that favored nighttime formation of surface hoar. Temperature and radiation observations showed that daytime solar heating often warmed the near-surface snow above the air temperature, contributing to mass transfer favoring crust formation and then surface hoar formation. Subsequent investigation of the WDC06A deep ice core revealed that crusts are preserved through the bubbly ice, and some occur in snow accumulated during winters, although not as commonly as in summertime deposits. Although no one has been on site to observe crust formation during winter, it may be favored by greater wintertime wind-packing from stronger peak winds, high temperatures and steep temperature gradients from rapid midwinter warmings reaching as high as −15 °C, and perhaps longer intervals of surface stability. Time-variations in crust occurrence in the core may provide paleoclimatic information, although additional studies are required. Discontinuity and cracking of crusts likely explain why crusts do not produce significant anomalies in other paleoclimatic records.

Citation: Fegyveresi, J. M., Alley, R. B., Muto, A., Orsi, A. J., and Spencer, M. K.: Surface formation, preservation, and history of low-porosity crusts at the WAIS Divide site, West Antarctica, The Cryosphere Discuss., https://doi.org/10.5194/tc-2016-155, in review, 2016.
John M. Fegyveresi et al.
John M. Fegyveresi et al.
John M. Fegyveresi et al.

Viewed

Total article views: 433 (including HTML, PDF, and XML)

HTML PDF XML Total Supplement BibTeX EndNote
301 70 62 433 38 19 58

Views and downloads (calculated since 29 Jun 2016)

Cumulative views and downloads (calculated since 29 Jun 2016)

Saved

Discussed

Latest update: 22 Nov 2017
Publications Copernicus
Download
Short summary
Observations at the WAIS Divide site in West Antarctica, show that near-surface snow is strongly altered by weather-related processes, such as strong winds and temperature fluctuations, producing features that are recognizable within the WDC06A ice core. Specifically, over 10 000 prominent crusts were observed in the upper 560 m of the core. We show that these crusts develop more often in summers, during relatively low-wind, low-humidity, clear-sky periods with intense daytime sunshine.
Observations at the WAIS Divide site in West Antarctica, show that near-surface snow is strongly...
Share