Abstract
Abstract. This study presents a reanalysis of the glaciologically obtained annual glacier mass balances at Hintereisferner, Ötztal Alps, Austria, for the period 2001–2011. The reanalysis is accomplished through a comparison with geodetically derived mass changes, using annual high-resolution airborne laser scanning (ALS). The grid-based adjustments for the method-inherent differences are discussed along with associated uncertainties and discrepancies of the two methods of mass balance measurements. A statistical comparison of the two datasets shows no significant difference for seven annual, as well as the cumulative, mass changes over the 10-year record. Yet, the statistical view hides significant differences in the mass balance years 2002/03 (glaciological minus geodetic records = +0.92 m w.e.), 2005/06 (+0.60 m w.e.), and 2006/07 (−0.45 m w.e.). We conclude that exceptional meteorological conditions can render the usual glaciological observational network inadequate. Furthermore, we consider that ALS data reliably reproduce the annual mass balance and can be seen as validation or calibration tools for the glaciological method.
Highlights
The mass balance of a glacier defines its hydrological reservoir function (e.g. Kaser et al, 2010) and is a reliable indicator of climate change (e.g. Vaughan et al, 2013; Bojinski et al, 2014)
Note that the uncertainty range σglac = ±0.21 m w.e. represents the random uncertainty as assessed in Sect. 3.1 and does not reflect any possible deficiencies in the glaciological series which shall be detected in the subsequent reanalysis
In search for possible causes of these large discrepancies between the methods in three of the sampled years, we explore the potential contribution of individual components of geod in the years of concern: the influence of temporary snow cover ( digital elevation models (DEMs)) on the geodetic mass balances is high, but a thorough consideration in our study ensures that the results are within the 95 % confidence interval
Summary
The mass balance of a glacier defines its hydrological reservoir function (e.g. Kaser et al, 2010) and is a reliable indicator of climate change (e.g. Vaughan et al, 2013; Bojinski et al, 2014). Zemp et al, 2009) This small number of directly measured annual glacier mass balance series provides the basis for reconstructing past contributions to sea level rise Kaser et al, 2006; Marzeion et al, 2012; Gardner et al, 2013; Vaughan et al, 2013); extrapolating glacier contribution to regional water supply The interconnection of different methods is increasingly suggested in order to advance glacier
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