64 th EASTERN SNOW CONFERENCE St. John’s, Newfoundland, Canada 2007 9 High-Resolution Near-Surface Snow Stratigraphy Inferred from Ground-Based 8-18 Ghz FMCW Radar Measurements: Devon Ice Cap, Nunavut, Canada 2005-06, Cryosat Validation Experiment MICHAEL N. DEMUTH 1,2 , HANS-PETER MARSHALL 3,4 , AND ELIZABETH M. MORRIS 5 ABSTRACT Broadband microwave Frequency Modulated Continuous Wave (FMCW) radar measurements were made during the spring of 2005 and 2006, at the CryoSat validation site on Devon Ice Cap, Nunavut, Canada. Metal reflector experiments were performed by inserting a large metal plate into a snowpit, parallel to visually identified layer transitions. This allowed unambiguous identification of specific radar reflections, which were relatively continuous in the region surrounding the study site (weak percolation facies). By mapping the snow depth to a given reflector, accumulation rate patterns over large areas can be estimated at high spatial resolution. We found that the depth to a given layer was shown to decrease in variability with depth, and that two spatial scales become evident in the structure, exhibiting lags of approximately 5 and 20 meters. Coincident measurements of surface hardness using a Snow-Micro-Penetrometer show more variability than layer depth, and also indicate an important process scale at ~ 5 m. We speculate that these spatial scales are related to the development of sastrugi, its burial and antecedent control of percolating meltwater, and suggest other complimentary data sources to further this line of inquiry. INTRODUCTION Reconnaissance methods employing lidar or radar altimeters aboard satellite and aircraft platforms are increasingly being used to study the variation of global and regional land ice mass budgets (e.g., Abdalati et al., 2004; Hopkinson and Demuth, 2006; Thomas et al., 2001; Zwalley et al., 2005). Because of surface motion and glacier dynamics, the principle challenge from a sea level change or water resources perspective is to retrieve mass change data from repeat measurements of surface height change. It is therefore necessary to understand more fully, processes that control internal layer development, densification and variability of the near-surface strata. This paper describes the use of several precision and portable instruments towards a larger effort to understand this variability and the processes responsible for it across regions representative of Benson’s glaciological facies assemblage (Benson, 1996), particularly for firn subject to percolation. 1 Natural Resources Canada – Geological Survey of Canada – Glaciology Section, 601 Booth Street, Ottawa, Canada, K1A 0E8: Mike.Demuth@NRCan.GC.CA 2 University of Reading – Environmental Systems Science Centre, U.K. 3 U.S. Army Cold Regions Research and Engineering Laboratory 4 Institute for Arctic and Alpine Research, University of Colorado, U.S.A. 5 Scott Polar Research Institute, University of Cambridge, U.K.