Abstract
Abstract. We use high-resolution aerial photogrammetry to investigate glacier retreat in great spatial and temporal detail in the Ötztal Alps, a heavily glacierized area in Austria. Long-term in situ glaciological observations are available for this region as well as a multitemporal time series of digital aerial images with a spatial resolution of 0.2 m acquired over a period of 9 years. Digital surface models (DSMs) are generated for the years 2009, 2015, and 2018. Using these, glacier retreat, extent, and surface elevation changes of all 23 glaciers in the region, including the Vernagtferner, are analyzed. Due to different acquisition dates of the large-scale photogrammetric surveys and the glaciological data, a correction is successfully applied using a designated unmanned aerial vehicle (UAV) survey across a major part of the Vernagtferner. The correction allows a comparison of the mass balances from geodetic and glaciological techniques – both quantitatively and spatially. The results show a clear increase in glacier mass loss for all glaciers in the region, including the Vernagtferner, over the last decade. Local deviations and processes, such as the influence of debris cover, crevasses, and ice dynamics on the mass balance of the Vernagtferner, are quantified. Since those local processes are not captured with the glaciological method, they underline the benefits of complementary geodetic surveying. The availability of high-resolution multi-temporal digital aerial imagery for most of the glaciers in the Alps provides opportunities for a more comprehensive and detailed analysis of climate-change-induced glacier retreat and mass loss.
Highlights
The impacts of climate change are widespread and clearly visible in the Alps (Rogora et al, 2018) but evident in the dwindling glacier resources (Beniston et al, 2018; Sommer et al, 2020; Zekollari et al, 2019)
Surface height changed at the glacier tongue of the Hintereisferner by up to −20.4 ± 0.4 m during the 9 years from September 2009 to September 2018 (Fig. 4)
This study demonstrates the potential of aerial images and the resulting Digital surface models (DSMs) for analyzing glacier retreat in great spatial and temporal detail
Summary
The impacts of climate change are widespread and clearly visible in the Alps (Rogora et al, 2018) but evident in the dwindling glacier resources (Beniston et al, 2018; Sommer et al, 2020; Zekollari et al, 2019). By the end of this century, mean air temperatures are expected to rise further by several degrees Celsius (Gobiet et al, 2014; Hanzer et al, 2018) Due to this ongoing climate evolution, alpine glaciers may lose half of their volume by 2050 compared to 2017 (Zekollari et al, 2019). The response of glaciers to climatic variations is related to the glacier mass balance that can be measured, among others, directly, using the glaciological method, or indirectly, using the geodetic method For the latter, the volume change of a glacier is determined by integrating the elevation change between two surveys across the entire glacier surface.
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