Abstract
AbstractSpatio-temporal variability of the winter surface mass balance is a major uncertainty in the modelling of annual surface mass balance. Moreover, its measurement at high spatio-temporal resolution (sub-200 m) is very useful to force, calibrate or validate models. This study presents the results of year-round field campaigns to study the evolution of the surface mass balance in a ~2 km2 portion of the accumulation zone of the Mer de Glace (France). It is based on repeated LiDAR acquisitions, submergence-velocity measurements and meteorological records. The two methods used to quantify submergence velocities show good agreement. They present a linear temporal evolution without significant seasonal changes but display significant spatial variability. We conclude that a dense network of submergence velocity measurements is required to reduce the uncertainties when computing winter and annual surface mass balance from digital elevation model differencing. Finally, a hight spatio-temporal variability of the winter surface mass balance is highlighted (e.g., a std dev. of 0.92 m in April) even though the topography is homogeneous (std dev. of 25 m). Attempts to relate this variability to different morpho-topographic variables and wind-related indexes show the need for studies conducted at the snowfall event scale to obtain a better understanding of the variability in mass balance at the glacier scale.
Highlights
The long-term evolution of glacier surface mass balance is known to be a very good indicator of changing climate conditions (e.g., Haeberli and Beniston, 1998; Solomon and others, 2007)
Some studies have pointed out a strong sensitivity of annual to winter surface mass balance given that the thicker the winter snowpack, the later the snow/ice transition at the glacier surface, resulting in reduced summer ablation (e.g., Paul and others, 2004; Machguth and others, 2006; Dadic and others, 2010; Réveillet and others, 2017, 2018)
The main aim of this study was to evaluate the spatial distribution of surface mass balance in the accumulation zone of the Mer de Glace over the 2014–2015 hydrological year using monthly terrestrial LiDAR acquisitions
Summary
The long-term evolution of glacier surface mass balance is known to be a very good indicator of changing climate conditions (e.g., Haeberli and Beniston, 1998; Solomon and others, 2007). Many studies have focused on summer surface mass-balance modelling using approaches of varying complexity (e.g., Hock, 1999; Pellicciotti and others, 2005; Gabbi and others, 2014; Réveillet and others, 2017). Some studies have pointed out a strong sensitivity of annual to winter surface mass balance given that the thicker the winter snowpack, the later the snow/ice transition at the glacier surface, resulting in reduced summer ablation (e.g., Paul and others, 2004; Machguth and others, 2006; Dadic and others, 2010; Réveillet and others, 2017, 2018). Accumulation is considered to be the variable with the highest uncertainty in glacier surface mass-balance modelling. Assessing the spatiotemporal variability of the winter surface mass balance is important to model the annual surface mass-balance evolution with reduced uncertainties
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