HR: 0800h
AN: C21C-1133    [Abstracts]
TI: The Use of a Reflectorless Scanning Total Station for Non-Invasive Measurements of Snowpack and Glacial Ice Volumes.
AU: * Duane, W J
EM: bill.duane@port.ac.uk
AF: University of Portsmouth, Department of Geography, Buckingham Building, Lion Terrace, Portsmouth, PO1 3HE United Kingdom
AU: Pepin, N C
EM: nicholas.pepin@port.ac.uk
AF: University of Portsmouth, Department of Geography, Buckingham Building, Lion Terrace, Portsmouth, PO1 3HE United Kingdom
AU: Chowanski, K
EM: Kurt.Chowanski@colorado.edu
AF: University of Colorado, Mountain Research Station 818 County Rd 116, Nederland, CO 80466 United States
AU: Hardy, D R
EM: dhardy@geo.umass.edu
AF: University of Massachussets, Department of Geosciences Morrill Science Center 611 North Pleasant St, Amherst, MA 01003 United States
AB: Snow and ice distribution is a critical factor when determining how alpine and montane zones function. Annual snowpack development in mid-latitudes is of fundamental importance for water supply and runoff during the spring melt period. Additionally, the presence of lying snow has significant implications for the ecology of the high mountains, especially in the alpine tundra and montane forest zones. Ice in the form of glaciers is also of critical interest, particularly concerning water storage in the hydrological cycle and any long-term change due to climate forcing. It is time consuming to obtain accurate three-dimensional models of a snow or ice surface, and manual surveys using poles or stakes are extremely costly in terms of human resources, and in the case of a fresh snow surface, are invasive. This last point is of particular importance if there is other instrumentation above or below the snow surface. This poster describes the employment of a reflectorless, motorized total station with a `face-scan' capability allowing for a systematic, non-invasive method of creating digital terrain models of snow or ice surfaces. Using this technique, an irregularly shaped area can be delineated and a suitable grid resolution selected, before collecting the data. Any changes in the snow or ice elevation whether through accumulation, ablation or redistribution can then be derived and mapped relatively simply. Check observations to fixed targets can give an assessment of accuracies between scans such that objective confidence levels can be given to the results. Sub-centimetre accuracies in plan and height are regularly achieved. Two examples of applications using this methodology examine, a) snow redistribution in the sub-alpine forest zone of Niwot Ridge, Colorado, U.S.A. and b) ice-cliff retreat at the glacial margins on Mt. Kilimanjaro, Tanzania. In Colorado repeated scans of a large snowdrift in a sub-alpine clearing were collected on a daily basis during two field expeditions in March/April 2003 and February 2005. Short-term changes in the snow surface were measured and related to the spatial wind pattern across the drift for the same time period, to examine the role of snow redistribution due to wind climate. Such a study would be considerably more difficult and prone to errors if traditional invasive survey were employed. On Kilimanjaro a set of baseline scans of the glacier margin (ice cliffs up to 30 metres high) on the Northern Icefield at different spatial resolutions have been obtained. These will be supplemented in future with further scans to examine rates of retreat, not only in general terms, but also with respect to specific areas and ice cliff morphology.
DE: 0720 Glaciers
DE: 0736 Snow (1827, 1863)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3394 Instruments and techniques
SC: Cryosphere [C]
MN: Fall Meeting 2005