Arctic regions are known to be places where climate shift yields the most visible consequences. In this context, glaciers and their environment are highly subject to global warming effects. New dynamics are observed and the behaviour of arctic systems (such as glaciers, moraines, beaches, etc.) changes at rates visible over yearly observations. According to recent works on climate change impacts on the cryosphere, short/violent events are recently observed and are one characteristic of these changes. As a consequence, an accelerating rate of glacial and pro-glacial activity is observed, especially at the end of each hydrological season (early fall). As an example, many phases of streamflow increase/decrease are observed, transforming glacier outflows, moraine morphology, and re-organizing intra-moraine processes. Within only a few days, the morphology of some parts of the moraine can be completely changed. In order to observe and quantify these processes, reactive methods of survey are needed. That is why the use of commercial off the shelf – DJI Phantom3 Professional – unmanned aerial vehicle (UAV) for aerial photography acquisition combined with structure from motion analysis and digital elevation model computation were chosen. The robust architecture of this platform makes it well suited as a reliable picture acquisition system for high resolution (sub-decimetre) imaging. These increasingly popular methods, at a convergence of technologies including inertial guidance systems, long lasting batteries, and available computational power (both embedded and for image processing), allow to fly and to acquire data whatever the conditions of cloud cover. Furthermore, data acquisition is much more flexible than traditional satellite imagery: several flights can be performed in order to obtain the best conditions/acquisitions at a high spatiotemporal resolution. Moreover, the low-flying UAV yielding high picture resolution allows to generate high-resolution digital elevation models, and therefore, to measure accurately dynamics on the field with decimetre resolution in all three directions. Our objective is to show an experimental campaign of small UAV data acquisition in an arctic basin (Austre Lovén glacier, Svalbard, 78°N) separated by a few days. Knowing the changing conditions at this period, similar UAV flights have been reiterated in order to catch moraine dynamics. This allowed us to select two sets of images whose processing highlights and quantifies morphological changes into the moraine while a rain event occurred between two cold periods.

The change of Austre Lovénbreen, a 4.5 km² land-based glacier along the west coast of Spitsbergen, is investigated using geodetic methods and mass balance measurements over 1948–2013. For 2008−2013, annual mass balances computed on 36-stake measurements were obtained, in addition to annual mass balances reconstructed from the neighbouring glaciers, Midtre Lovénbreen (1968−2007) and Austre Brøggerbreen (1963−1967). The mean rate of glacier retreat for 1948–2013 is −16.7 ± 0.3 m a⁻¹. Fluctuations in area (1948–2013 mean, −0.027 ± 0.002 km² a⁻¹) showed a slowing as the glacier recedes within its valley from 1990 to 1995. For 1962–2013, the average volume loss calculated by digital elevation model subtraction of −0.441 ± 0.062 m w.e. a⁻¹ (or −0.54 ± 0.07% a⁻¹) is similar to the average annual mass balance (−0.451 ± 0.007 m w.e. a⁻¹), demonstrating a good agreement between the loss rates computed by both methods over 1962−2013. When divided in two periods (1962−1995 and 1995−2013), an increase in the rate of ice mass loss is statistically significant for the glacier volume change. The 0°C isotherm elevation (based on mean May–September air temperatures) is estimated to have risen by about 250 m up to the upper parts of the glacier between 1948 and 2013. The glacier area exposed to melting during May to September almost increased by 1.8-fold while the area reduced by a third since 1948. Within a few years, the glacier area exposed to melting will decrease, leading the upper glacier parts under the 0°C isotherm while the snout will keep on retreating.

The volume variation of a glacier is the actual indicator of long term and short term evolution of the glacier behaviour. In order to assess the volume evolution of the Austre Lovénbreen (79° N) over the last 47 years, we used multiple historical datasets, complemented with our high density GPS tracks acquired in 2007 and 2010. The improved altitude resolution of recent measurement techniques, including phase corrected GPS and LiDAR, reduces the time interval between datasets used for volume subtraction in order to compute the mass balance. We estimate the sub-metre elevation accuracy of most recent measurement techniques to be sufficient to record ice thickness evolutions occurring over a 3 year duration at polar latitudes.The systematic discrepancy between ablation stake measurements and DEM analysis, widely reported in the literature as well as in the current study, yields new questions concerning the similarity and relationship between these two measurement methods.The use of Digital Elevation Model (DEM) has been an attractive alternative measurement technique to estimate glacier area and volume evolution over time with respect to the classical in situ measurement techniques based on ablation stakes. With the availability of historical datasets, whether from ground based maps, aerial photography or satellite data acquisition, such a glacier volume estimate strategy allows for the extension of the analysis duration beyond the current research programmes. Furthermore, these methods do provide a continuous spatial coverage defined by its cell size whereas interpolations based on a limited number of stakes display large spatial uncertainties. In this document, we focus on estimating the altitude accuracy of various datasets acquired between 1962 and 2010, using various techniques ranging from topographic maps to dual frequency skidoo-tracked GPS receivers and the classical aerial and satellite photogrammetric techniques.