Recent evolution of an ice‐cored moraine at the Gentianes Pass, Valais Alps, Switzerland

International audienceLateral moraines located in permafrost environments often preserve large amounts of both glacier and periglacial ice. To understand how ice‐cored moraines located in high alpine environments evolve in a context of both glacier retreat and permafrost degradation, we performed 11 terrestrial laser‐scanning measurement campaigns between 2007 and 2014 on a highly anthropogenic overprinted moraine prone to instability. Resulting comparison of the subsequent 3D models allowed to qualitatively and quantitatively analyze the morphological evolution of the moraine. The comparisons indicate a very high geomorphic activity of the moraine including large areas affected by downslope movements of blocks and 10 landslides with a volume between 24 ± 1 and 1,138 ± 47 m3. Data also indicated a very strong ice melt with a loss of ice thickness locally reaching 17.7 m at the foot of the moraine. These results, compared with resistivity and thermal measurements of the ground, suggest the combined role of ice loss at the foot of the moraine and the permafrost activity/warming in triggering these processes

A Strategy Based on Maximum Spanning Trees to Stitch Together Microscope Images

Assembling partial views is an attractive means to extend the field of view of microscope images. In this paper, we propose a semi-automated solution to achieve this goal. Its intended audience is the microscopist who desires to scan a large area while acquiring a series of partial views, but who does not wish to—or cannot—planify the path of the scan. In a first stage, this freedom is dealt with by interactive manipulation of the resulting partial views, or tiles. In a second stage, the position of the tiles is refined by a fully automatic pairwise registration process. The contribution of this paper is a strategy that determines which pairs of tiles to register, among all possible pairs. The central tenet of our proposed strategy is that two tiles that happen to possess a large common area will register with higher accuracy than two tiles with a smaller overlap. Our strategy is then to minimize the number of pairwise registrations while maximizing the global amount of overlap, and while ensuring that the local registration efforts are sufficient to link all tiles together to yield a global mosaic. By stating this requirement in a graph-theoretic context, we are able to derive the optimal solution thanks to Kruskal's algorithm

Assistive navigational devices that incorporate principles of spatial cognition and imagery

We investigate a systems approach to developing a new class of assistive devices for the visually disabled. This systems approach consists of a simultaneous exploration of the content of mental representations of space in both the blind and the sighted, the development of a design method that aims at improving the ability of the visually disabled to elaborate mental representations of the space through which they are moving, and the development of socially anchored evaluation methods that ensure our new class of devices serve the needs of the disabled. This systems approach has led us to investigate a new aspect of the experience of the disabled—their personal safety and their perception of personal security. Safety and security have not been widely studied, except within a narrow definition of physical safety. Hence we use the fundamental research in spatial cognition to probe aspects of mental representations we expect to exploit in the development cycle, we investigate the concepts of safety and security from a social and psychological perspective and focus on the development of new evaluation indicators based on these concepts, and then introduce both these elements into a modified engineering design process and validation cycle. We illustrate the approach in terms of several projects presently under development

Permafrost in Switzerland 2004/2005 and 2005/2006

The present report covers the period from October 2004 to September 2006. It is the last report of the pilot phase 2000–2006 of the network for permafrost monitoring in Switzerland (PERMOS). At this point, PERMOS includes (a) 11 drill sites (including 22 boreholes and geophysical monitoring at 4 of the sites), (b) 11 surface temperature sites (including measurements in loose debris at 9 sites, in bedrock at 5 sites, and at the bottom of the snow cover (BTS) at 3 sites), and (c) aerial photographs taken by Swisstopo. Winter 2004/2005 was characterized by an early and thin snow cover in the higher alpine regions and an early snow melt in spring. A long phase of above average air temperatures followed, which lasted until July and made summer 2005 the second warmest on record. Winter 2005/2006 started late, had a long lasting thick snow cover, and was followed by a warm summer with the hottest July ever measured. Active layer thicknesses in summer 2004 were similar to those before 2003 at most sites. Hence, thermal changes in the subsurface from the 2003 heat wave were not sustained, although the ice content at the permafrost table may have been permanently modified. The active layer deepened again in several boreholes in summer 2005, reaching values similar to 2003, and remained more or less stable in summer 2006. At ca. 10 m depth, ground temperatures at the drill sites displayed a warming until the beginning of 2005, which results from the preceding heat period in summer 2003. Then, mainly as a result of the snow conditions in winter, a cooling period followed. Since 2005, temperature observations are complemented by electrical resistivity tomography (ERT) measurements at 4 drill sites to monitor physical properties of the ground (e.g., ice content or unfrozen water content). The ERT monitoring strategy is outlined and discussed in this report. Ground surface temperatures (GST) were low in both years of the reporting period, especially during winter. In 2005, GST temporarily dropped to new minima and reached about mean values of the past decade at the end of the reporting period. Rock surface temperatures (RST) were integrated into PERMOS in summer 2004 and are presented and discussed in detail in this report. Temperature values in steep rock clearly display the cold conditions in winter 2004/2005 as well as the warm summer 2006. The chapter on special aspects of permafrost monitoring is dedicated to the observed acceleration of rock glaciers in the past two decades. The destabilization of several landforms shows that permafrost creep conditions in the Alps are changing. In general, both, surface temperatures and ground temperatures in the uppermost meters decreased to pre-2003 conditions at all sites during the reporting period, which is mainly a result of the snow conditions

Recent interannual variations of rock glacier creep in the European Alps

Recent interannual variations of rock glacier surface motion are compared for 16 landforms monitored for a few years in various parts of the European Alps. Large fluctuations have been observed particularly since 2002. Most investigated rock glaciers have shown a similar behavior whatever their location in the Alpine arc, their size, or their velocity. The observed interannual variations appear to be primarily related to external climatic factors rather than to internal characteristics. They are mostly well correlated with mean annual ground surface temperature shifts with a delay of a few months, reflecting the thermal wave propagation deeper into permafrost. Seasonal factors may also play a significant role: a lower intensity of winter ground freezing and/or a larger winter snow accumulation appear to facilitate a higher rate of rock glacier surface motion