AUTHOR=Pulwicki Alexandra , Flowers Gwenn E. , Bingham Derek 

TITLE=Pursuit of Optimal Design for Winter-Balance Surveys of Valley-Glacier Ablation Areas

JOURNAL=Frontiers in Earth Science

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2019.00199

DOI=10.3389/feart.2019.00199

ISSN=2296-6463

ABSTRACT=<p>Efficient collection of snow depth and density data is important in field surveys used to estimate the winter surface mass balance of glaciers. Simultaneously extensive, high resolution, and accurate snow-depth measurements can be difficult to obtain, so optimisation of measurement configuration and spacing is valuable in any survey design. Using <italic>in-situ</italic> data from the ablation areas of three glaciers in the St. Elias Mountains of Yukon, Canada, we consider six possible survey designs for snow-depth sampling and <italic>N</italic> = 6–200+ sampling locations per glacier. For each design and number of sampling locations, we use a linear regression on topographic parameters to estimate winter balance at unsampled locations and compare these estimates with known values. Average errors decrease sharply with increasing sample size up to <italic>N</italic> ≈ 10–15, but reliable error reduction for any given sampling scheme requires significantly higher <italic>N</italic>. Lower errors are often, but not always, associated with sampling schemes that employ quasi-regular spacing. With both real- and synthetic data, the common centreline survey produces the poorest results overall. The optimal design often requires sampling near the glacier margin, even at low <italic>N</italic>. The unconventional “hourglass” design performed best of all designs tested when evaluated against known values of winter balance.</p>