Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 9, 487-504, 2015
http://www.the-cryosphere.net/9/487/2015/
doi:10.5194/tc-9-487-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Mar 2015
Seasonal changes of ice surface characteristics and productivity in the ablation zone of the Greenland Ice Sheet
D. M. Chandler1, J. D. Alcock1, J. L. Wadham1, S. L. Mackie2, and J. Telling1 1Bristol Glaciology Centre, School of Geographical Sciences, Bristol University, Bristol, UK
2School of Earth Sciences, Bristol University, Bristol, UK
Abstract. Field and remote sensing observations in the ablation zone of the Greenland Ice Sheet have revealed a diverse range of ice surface characteristics, primarily reflecting the variable distribution of fine debris (cryoconite). This debris reduces the surface albedo and is therefore an important control on melt rates and ice sheet mass balance. Meanwhile, studies of ice sheet surface biological processes have found active microbial communities associated with the cryoconite debris, which may themselves modify the cryoconite distribution. Due to the considerable difficulties involved with collecting ground-based observations of the ice surface, our knowledge of the physical and biological surface processes, and their links, remains very limited. Here we present data collected at a field camp established in the ice sheet ablation zone at 67° N, occupied for almost the entire melt season (26 May–10 August 2012), with the aim of gaining a much more detailed understanding of the physical and biological processes occurring on the ice surface. These data sets include quadrat surveys of surface type, measurements of ice surface ablation, and in situ biological oxygen demand incubations to quantify microbial activity. In addition, albedo at the site was retrieved from AVHRR (Advanced Very High Resolution Radiometer) remote sensing data. Observations of the areal coverage of different surface types revealed a rapid change from complete snow cover to the "summer" (summer study period) ice surface of patchy debris ("dirty ice") and cryoconite holes. There was significant correlation between surface albedo, cryoconite hole coverage and surface productivity during the melt season, but microbial activity in "dirty ice" was not correlated with albedo and varied widely throughout the season. While this link suggests the potential for a remote-sensing approach to monitoring cryoconite hole biological processes, very wide seasonal and spatial variability in net surface productivity demonstrates the need for caution when extrapolating point measurements of biological processes to larger temporal or spatial scales.

Citation: Chandler, D. M., Alcock, J. D., Wadham, J. L., Mackie, S. L., and Telling, J.: Seasonal changes of ice surface characteristics and productivity in the ablation zone of the Greenland Ice Sheet, The Cryosphere, 9, 487-504, doi:10.5194/tc-9-487-2015, 2015.
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Short summary
The Greenland Ice Sheet surface shows a diverse range of characteristics, and hosts active microbial communities in debris-rich ''cryoconite holes'' (CHs). Field and satellite data for a complete melt season revealed significant links between surface albedo, CH coverage and biological activity. This suggests satellites may be able to monitor CH biological processes. Nevertheless, caution is needed when extrapolating point measurements of biological processes to larger space and time scales.
The Greenland Ice Sheet surface shows a diverse range of characteristics, and hosts active...
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