Surface Mass-Balance Gradients From Elevation and Ice Flux Data in the Columbia Basin, Canada

The mass-balance—elevation relation for a given glacier is required many numerical models of ice flow. Direct measurements this using remotely-sensed methods are complicated by dynamics, so observations currently limited to glaciers where surface mass-balance routinely made. We test the viability continuity equation estimate annual mass balance between flux-gates in absence situ measurements, on five Columbia Mountains British Columbia, Canada. Repeat airborne laser scanning surveys elevation, penetrating radar and publicly available maps thickness used changes elevation flux. evaluate approach comparing modeled observed balance. Modeled gradients well-approximate those obtained from direct measurement balance, with mean difference +6.6 ± 4%. Regressing equilibrium line altitudes average 15 m higher than satellite-observations transient snow line. Estimates over flux bins compare less favorably gradients. Average error (+0.03 id="m2">± 0.07 w.e.) relatively small, yet absolute (0.55 id="m3">± 0.18 uncertainty (0.57 large. Mass conservation, assessed glaciological data, respected (when estimates within 1? uncertainties) 84% representing 86% total area. Uncertainty velocity, especially areas velocity low (<10 ?1 ) contributes greatest estimating find that thicknesses yields comparable relative thickness, but we caution against over-interpreting individual flux-bin balances due large residuals. Given performance increasing availability topography suggest similar efforts produce modern high-resolution datasets feasible larger scales.