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 the 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 1 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 of water equivalent per year (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.
Highlights
Glacier surface mass balance observations are widely used to assess climate change in various climatic regimes because of their sensitivity to climate variables (e.g. Zemp et al, 2019; Marzeion et al, 2014; Kaser et al, 2006; Gardner et al, 2013; Huss and Hock, 2018; IPCC, 2019)
Considerable efforts have been made to assess ice volume changes at the mountainrange scale over long time periods using geodetic measurements obtained from remote sensing techniques (e.g. Paul and Haeberli, 2008; Abermann et al, 2011; Gardelle et al, 2012; Gardner et al, 2013; Berthier et al, 2014; Brun et al, 2017)
The objective of this paper is to propose an approach to determine point surface mass balances from measurements obtained by remote sensing techniques
Summary
Glacier surface mass balance observations are widely used to assess climate change in various climatic regimes because of their sensitivity to climate variables (e.g. Zemp et al, 2019; Marzeion et al, 2014; Kaser et al, 2006; Gardner et al, 2013; Huss and Hock, 2018; IPCC, 2019). Considerable efforts have been made to assess ice volume changes at the mountainrange scale over long time periods using geodetic measurements obtained from remote sensing techniques (e.g. Paul and Haeberli, 2008; Abermann et al, 2011; Gardelle et al, 2012; Gardner et al, 2013; Berthier et al, 2014; Brun et al, 2017) These geodetic methods determine glacier-wide volume changes, or glacier-wide mass balances, by differencing repeated determinations of glacier surface elevations obtained from airborne and spaceborne surveys usually over multi-year to decadal periods (e.g. Vincent, 2002; Bauder et al, 2007; Soruco et al, 2009; Berthier et al, 2014; Dussaillant et al, 2019). These methods are effective for estimating the overall glacier mass change and quantifying the related hydrological impacts or sea level contribution
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