Calculating Snowline Altitudes on Glaciers with Patchy and Irregular Snow Cover Using Satellite Imagery

Previous studies have mapped end-of-season snowlines (ESS) on glaciers from satellite imagery to find their snowline altitudes (SLA) to use as a proxy for the glacier equilibrium line altitude (ELA). A line is traced along the boundary between snow and ice, then, from a digital elevation model (DEM), elevation values are extracted at regular intervals along the line. The average elevation of these points is taken to be the SLA. While this approach would be advantageous, as it offers a solution to measuring glacier ELAs in remote regions, it is prone to an oversampling bias. Where snow cover is patchy, for example, in shaded areas or where avalanching has occurred, a greater length of line is mapped in order to follow the snow-ice boundary than is required for smoother segments. This is regardless of whether the region contributes a larger area of snow cover or not. Consequently, SLA calculations are prone to oversampling from areas of irregular snow cover. Even when the ESS is mapped accurately and precisely, the SLA value may differ significantly from the true ELA. This poster investigates alternative methods of calculating the SLA from mapped ESSs to reduce bias towards patchy and irregular areas of snow cover.