Accurately estimating the net seasonal snow accumulation (or “winter balance”) on glaciers is central to assessing glacier health and predicting glacier runoff. However, measuring and modeling snow distribution is inherently difficult in mountainous terrain, resulting in high uncertainties in estimates of winter balance. Our work focuses on uncertainty attribution within the process of converting direct measurements of snow depth and density to estimates of winter balance. We collected more than 9000 direct measurements of snow depth across three glaciers in the St. Elias Mountains, Yukon, Canada in May 2016. Linear regression (LR) and simple kriging (SK), combined with cross correlation and Bayesian model averaging, are used to interpolate estimates of snow water equivalent (SWE) from snow depth and density measurements. Snow distribution patterns are found to differ considerably between glaciers, highlighting strong inter- and intra-basin variability. Elevation is found to be the dominant control of the spatial distribution of SWE, but the relationship varies considerably between glaciers. A simple parameterization of wind redistribution is also a small but statistically significant predictor of SWE. The SWE estimated for one study glacier has a short range parameter (90 m) and both LR and SK estimate a winter balance of ~0.6 m w.e. but are poor predictors of SWE at measurement locations. The other two glaciers have longer SWE range parameters (~450 m) and due to differences in extrapolation, SK estimates are more than 0.1 m w.e. (up to 40%) lower than LR estimates. By using a Monte Carlo method to quantify the effects of various sources of uncertainty, we find that the interpolation of estimated values of SWE is a larger source of uncertainty than the assignment of snow density or than the representation of the SWE value within a terrain model grid cell. For our study glaciers, the total winter balance uncertainty ranges from 0.03 (8%) to 0.15 (54%) m w.e. depending primarily on the interpolation method. Despite the challenges associated with accurately and precisely estimating winter balance, our results are consistent with the previously reported regional accumulation gradient.

Gas and vapour emissions from subglacial or subnivean volcanoes are capable of melting voids and passageways, here termed glaciovocanic caves and chimneys, in the overlying ice/snow. Glaciovolcanic caves (sub-horizontal) and chimneys (vertical) have been documented within a variety of volcanic regions around the world, with their formation sometimes preceding volcanic eruptions. Studying the formation and evolution of glaciovolcanic caves and chimneys and their relation to changes within the associated volcanic and glacial systems, therefore has potential to inform glaciovolcanic hazard assessments. In 2016, glaciovolcanic chimneys were discovered within Job Glacier in the Mt. Meager Volcancic Complex, British Columbia, Canada. The hypothesis that the chimneys formed as a result of glacier thinning, rather than due to an increase in volcanic activity, has yet to be tested. Here we seek to describe the morphology of these glaciovolcanic features, with respect to glaciological conditions and geothermal heat fluxes, using analytical models. By adapting existing analytical models of subglacial hydrological channels to account for the flow of geothermal gases instead of water, we derive the opening and closure rates for glaciovolcanic caves and chimneys. We use idealized glacier geometries and simplified descriptions of the energy transfer between the geothermal gases and the ice walls to facilitate our analysis. Steady-state geometries are found by balancing the melt opening, internal energy loss and the closure due to ice creep, and presented as functions of glacier thickness and geothermal heat flux. Our analytical results will be used to guide numerical simulations with more complex geometries and transient glaciovolcanic conditions. A better understanding of these complex interactions will facilitate more effective assessment of potential precursory signals of volcanic activity.