Modeling Ablation on Place Glacier, British Columbia, from Glacier and Off-glacier Data Sets

Abstract

The results of two simulations of hourly ablation, from late July to September 2002, at a site on the Place Glacier are described. First, ablation is modeled from a data set collected at the glacier site; second, from a data set collected off-glacier at a site below the glacier tongue. The glacier data set simulations, based as they are on global and reflected short-wave radiation measurements, a net long-wave radiation model and the bulk turbulent heat transfer approach, provides a reasonably good simulation of cumulative ablation, amounting to almost 1.2 m during the experimental period, mostly due to melting out of the preceding winter snowpack. Average melt component flux densities due to net short-wave radiation, net long-wave radiation, sensible heat and latent heat due to moisture exchange are 93.1, −22.6, 14.4 and 3.91 W m⁻², respectively, during this time. The glacier site data are also used to fit a snow albedo model to albedo measurements for old and new snow cover. The albedo model is then used in the second simulation, which is based on global radiation measurements, a similar net long-wave radiation model, and a heat transfer approach in which turbulent mixing due to katabatic and geostrophic flow is parameterized from the off-glacier temperature data. The second simulation scheme performs best if the katabatic component of the parameterization scheme is suppressed because the wind regime at the glacier site appears to be intermittent, but the scheme itself is based upon the idea of a continuously flowing glacier wind.

Acknowledgments

Support for this work has been provided by Environment Canada through its Cryospheric Systems program, the Natural Sciences and Engineering Research Council of Canada, and, currently, the Canada Foundation for Climate and Atmospheric Science. Infrastructure support has been provided through the Canadian Glacier Variations Monitoring and Assessment Network, headed by M. N. Demuth, Natural Resources Canada. The authors have also benefited from collaboration with R. D. Moore, University of British Columbia, as well as from the constructive comments of F. Pellicciotti, ETH, Switzerland, and one other reviewer.