Geodetic point surface mass balances: A new approach to determine point surface mass balances from remote sensing measurements

Abstract

Abstract. Mass balance observations are very useful to assess climate change in different regions of the world. As opposed to glacier-wide mass balances, which are influenced by the dynamic response of each glacier, point mass-balances provide a direct climatic signal that depends on surface accumulation and ablation only. Unfortunately, major efforts are required to conduct in situ measurements on glaciers. Here, we propose a new approach that determines point surface mass balances from remote sensing observations. We call this balance the geodetic point surface mass balance. From observations and modelling performed on Argentière and Mer de Glace glaciers over the last decade, we show that the vertical ice flow velocity changes are small in areas of low bedrock slope. Therefore, assuming constant vertical velocities in time for such areas and provided that the vertical velocities have been measured for at least one year in the past, our method can be used to reconstruct annual point surface mass balances from surface elevations and horizontal velocities alone. We demonstrate that the annual point surface mass balances can be reconstructed with an accuracy of about 0.3 m w.e. a−1 using the vertical velocities observed over the previous years and data from Unmanned Aerial Vehicle images. Given the recent improvements of satellite sensors, it should be possible to apply this method to high spatial resolution satellite images as well.

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

“…Recent efforts to remotely estimate surface mass balance are limited but growing (Bisset et al, 2020;Gao et al, 2020;Young et al, 2020;Vincent et al, 2021). Some of these approaches resolve point mass-balance but require data inputs which render them more suitable for individual glaciers (Young et al, 2020), or specific areas of individual glaciers (Vincent et al, 2021). Vincent et al (2021) derive point surface mass balances from vertical ice velocities and surface elevation change.…”

“…Some of these approaches resolve point mass-balance but require data inputs which render them more suitable for individual glaciers (Young et al, 2020), or specific areas of individual glaciers (Vincent et al, 2021). Vincent et al (2021) derive point surface mass balances from vertical ice velocities and surface elevation change. Their method estimates point surface mass balance, and demonstrates the potential for expanding the limited number of point observations of surface mass balance available globally, but relies upon an assumption of constant vertical ice velocities and requires a dense network of in situ observations, which limits application of their approach in space and time.…”

“…Using a single velocity mosaic rather than annual mosaics only slightly increases ME on modeled b a . For relatively small mountain glaciers, velocity changes over short periods (e.g., three years) will typically be within velocity uncertainty, and a single ice velocity can be used to represent the period, as done by Vincent et al (2021). Theoretically, the change in velocity due to creep from 4.95 m of thinning over the tongue of Conrad Glacier from 2016 to 2018 would yield a 2.5% decrease in velocity, well within our reported uncertainty of ice velocity.…”

“…The lack of subglacial topographic information limits calculation of ice flux to relatively few glaciers (e.g., Berthier et al, 2003;Vincent et al, 2009;Belart et al, 2017;Rabatel et al, 2018;Bisset et al, 2020;Young et al, 2020). Previous efforts to infer the spatial distribution of mass balance from ice flux have primarily focused on glacier tongues (e.g., Gudmundsson and Bauder, 1999;Kääb and Funk, 1999;Berthier et al, 2003;Vincent et al, 2009Vincent et al, , 2021Berthier and Vincent, 2012;Gao et al, 2020), where ice thickness, glaciological balance and ice velocity measurements are most numerous, density is assumed to be that of ice, and glacier geometry is simplest.…”

Estimating surface mass balance patterns from UAV measurements on the ablation area of the Morteratsch-Pers glacier complex (Switzerland)

“…Different approaches exist to calculate the ice flux divergence ranging from the use of 3D ice flow models (Seroussi et al, 2011;Vincent et al, 2020) to the use of simple geometric calculations and flux gates (Nuimura et al, 2011;Berthier and Vincent, 2012). The important distinction is the simplicity and the resolution with which they can be calculated.…”