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Ground temperatures in coarse, blocky deposits such as mountain blockfields and rock glaciers have long been observed to be lower in comparison with other (sub)surface material. One of the reasons for this negative temperature anomaly is the lower soil moisture content in blocky terrain, which decreases the duration of the zero curtain in autumn. Here we used the CryoGrid community model to simulate the effect of drainage on the ground thermal regime and ground ice in blocky terrain permafrost at two sites in Norway. The model set-up is based on a one-dimensional model domain and features a surface energy balance, heat conduction and advection, as well as a bucket water scheme with adjustable lateral drainage. We used three idealized subsurface stratigraphies, blocks only, blocks with sediment and sediment only, which can be either drained (i.e. with strong lateral subsurface drainage) or undrained (i.e. without drainage), resulting in six scenarios. The main difference between the three stratigraphies is their ability to retain water against drainage: while the blocks only stratigraphy can only hold small amounts of water, much more water is retained within the sediment phase of the two other stratigraphies, which critically modifies the freeze–thaw behaviour. The simulation results show markedly lower ground temperatures in the blocks only, drained scenario compared to other scenarios, with a negative thermal anomaly of up to 2.2 ∘C. For this scenario, the model can in particular simulate the time evolution of ground ice, with build-up during and after snowmelt and spring and gradual lowering of the ice table in the course of the summer season. The thermal anomaly increases with larger amounts of snowfall, showing that well-drained blocky deposits are less sensitive to insulation by snow than other soils. We simulate stable permafrost conditions at the location of a rock glacier in northern Norway with a mean annual ground surface temperature of 2.0–2.5 ∘C in the blocks only, drained simulations. Finally, transient simulations since 1951 at the rock glacier site (starting with permafrost conditions for all stratigraphies) showed a complete loss of perennial ground ice in the upper 5 m of the ground in the blocks with sediment, drained run; a 1.6 m lowering of the ground ice table in the sediment only, drained run; and only 0.1 m lowering in the blocks only, drained run. The interplay between the subsurface water–ice balance and ground freezing/thawing driven by heat conduction can at least partly explain the occurrence of permafrost in coarse blocky terrain below the elevational limit of permafrost in non-blocky sediments. It is thus important to consider the subsurface water–ice balance in blocky terrain in future efforts in permafrost distribution mapping in mountainous areas. Furthermore, an accurate prediction of the evolution of the ground ice table in a future climate can have implications for slope stability, as well as water resources in arid environments.

Rock glaciers are geomorphological expressions of permafrost. Close to sea level in northernmost Norway, in the subarctic Nordkinn peninsula, we have observed several rock glaciers that appear to be active now or were active in the recent past. Active rock glaciers at this elevation have never before been described in Fennoscandia, and they are outside the climatic limits of present-day permafrost according to models. In this study, we have investigated whether or not these rock glaciers are active under the current climate situation. We made detailed geomorphological maps of three rock glacier areas in Nordkinn and investigated the regional ground dynamics using synthetic aperture radar interferometry (InSAR). One of the rock glaciers, namely the Ivarsfjorden rock glacier, was investigated in more detail by combining observations of vertical and horizontal changes from optical images acquired by airborne and terrestrial sensors and terrestrial laser scans (TLSs). The subsurface of the same rock glacier was investigated using a combination of electrical resistivity tomography (ERT) and refraction seismic tomography (RST). We also measured ground surface temperatures between 2016 and 2020, complemented by investigations using an infrared thermal camera, and a multi-decadal climatic analysis. We mapped the rock glaciers in the innermost parts of Store and Lille Skogfjorden as relict, while the more active ones are in the mouths of both fjords, fed by active talus in the upper slopes. Several of the rock glaciers cross over both the Younger Dryas shoreline (25 m a.s.l.) and the Early to Mid-Holocene shoreline at 13 m a.s.l. Both InSAR and optical remote sensing observations reveal low yearly movement rates (centimetres to millimetres per year). The ERT and RST suggest that there is no longer permafrost and ground ice in the rock glacier, while temperature observations on the front slope indicate freezing conditions also in summer. Based on the in situ temperature measurements and the interpolated regional temperature data, we show that the mean annual air temperature (MAAT) of the region has risen by 2 ∘C since the late 19th century to about 1.5 ∘C in the last decade. MAATs below 0 ∘C 100–150 years ago suggest that new rock glacier lobes may have formed at the end of the Little Ice Age (LIA). These combined results indicate that the Nordkinn rock glaciers are transitioning from active to relict stages. The study shows that transitional rock glaciers are still affected by creep, rock falls, snow avalanches, etc., and are not entirely dynamically dead features. Our contrasting results concerning permafrost presence and rock glacier activity show the importance of a multi-methodological approach when investigating slope processes in the edge zones of permafrost influence.

This research was funded by the European Space Agency Permafrost-CCI project (grant number 4000123681/18/I-NB). Rock glaciers are landforms related to permafrost creep that are sensitive to climate variability and change. Their spatial distribution and kinematic behaviour can be critical for managing water resources and geohazards in periglacial areas. Rock glaciers have been inventoried for decades worldwide, often without assessment of their kinematics. The availability of remote sensing data however makes the inclusion of kinematic information potentially feasible, but requires a common methodology in order to create homogeneous inventories. In this context, the International Permafrost Association (IPA) Action Group on rock glacier inventories and kinematics (2018-2023), with the support of the European Space Agency (ESA) Permafrost Climate Change Initiative (CCI) project, is defining standard guidelines for the inclusion of kinematic information within inventories. Here, we demonstrate the feasibility of applying common rules proposed by the Action Group in 11 regions worldwide. Spaceborne interferometric synthetic aperture radar (InSAR) was used to characterise identifiable moving areas related to rock glaciers, applying a manual and a semi-automated approach. Subsequently, these areas were used to assign kinematic information to rock glaciers in existing or newly compiled inventories. More than 5000 moving areas and more than 3600 rock glaciers were classified according to their kinematics. The method and the preliminary results were analysed. We identified drawbacks related to the intrinsic limitations of InSAR and to various applied strategies regarding the integration of non-moving rock glaciers in some investigated regions. This is the first internationally coordinated work that incorporates kinematic attributes within rock glacier inventories at a global scale. The results show the value of designing standardised inventorying procedures for periglacial geomorphology. Copyright: © 2022 Aldo Bertone et al. Publisher PDF

Blockfields remain enigmatic regarding their origin, internal structure, surface processes, and glaciological implications. In Scandinavia, blockfields are found on high-elevation, low-relief mountains (plateaus) across the Arctic and Subarctic. In this study, we present a 1D numerical model that uses near-surface temperatures measured between summer 2018 and summer 2020 to calculate frost-cracking intensities (FCI) within the ground column in three different blockfields in Norway and Svalbard. Eighty-nine miniature temperature loggers were distributed on Tron Mountain (1650 m a.s.l.) in Alvdal, Gamlemsveten (780 m a.s.l.) near Ålesund in southwestern Norway and on Platåberget (460 m a.s.l.) near Longyearbyen, Svalbard. We modelled FCI by scaling the time spent in the frost cracking window (between −3 and −8°C) with the temperature gradient and a penalty function for distance to available water. At Tron and Gamlemsveten, ground temperatures never reached the frost cracking window at one third of our sites due to insulation by a thick snow cover in depressions and on the lee sides of summits. The highest FCI (0.05–0.4 K m) are obtained where the subsurface consists of boulders and stones in a matrix of relatively fine sediment (sand, silt, gravel). In contrast, very low FCI (0.003–0.02 K m) were modelled for blocky layers with large air-filled pores because of the low water availability. On Platåberget, all sensors reached the frost-cracking window during the annual temperature cycle, but FCI are extremely low (0.0004–0.15 K m) as water availability is limited due to (i) permafrost and (ii) near-surface temperatures remaining below the frost-cracking window for 3/4 of the year. This indicates that boulder-rich blockfields with air-filled hollows are preserved in very cold climates, whereas warmer, maritime settings with higher availability of fine interstitial material place blockfields in the fast lane for frost weathering.

Rock walls in high mountain areas are the expression of long–term slopes response (103–105 years) to tectonics, weathering and denudation and a major source of sediment and hazard. Controls of mountain rock walls (RW) distribution and the response to post-glacial evolution are rarely discussed in the literature at the scale of mountain ranges. Using a database of 791 RW mapped in the Romanian Carpathians, we present their distribution and morphometry in respect to lithological classes, structural features and topography and relate their exposure to post–Younger Dryas (Holocene) rock slope failure chronology. Statistical analysis results show the high significance of structural and tectonic control on RW distribution, which prevails in sedimentary units where it imposed the predominance of West and North orientations and led to the formation of RW with dimensions up to a degree higher compared to other lithologies. Morphometric data indicate that metamorphic and igneous RW (linked to a great extent to glacial valleys and cirques headwalls) are usually restricted to the highest sectors of the mountain slopes, being characterized by reduced relative heights, asymmetrically distributed, common on the North-exposed slopes and extremely rare on the South. Based on 38 in-situ produced 10Be surface exposure ages obtained on meter-sized boulders from the Southern and Eastern Carpathians, we hypothesise that metamorphic and igneous RW in the formerly glaciated Carpathian valleys were significantly shaped during Early Holocene (before 9 ka) by rock slope failures events that followed the deglaciation of the highest cirques and by intense RW permafrost degradation, which also affected some of the highest sedimentary units. We associate the long–term imprints of frost weathering to the significant North/South RW and rock glaciers distribution asymmetry, also identified in other mid-latitude mountain sites with similar topographic constraints.

In high‐latitude and mountain regions, local processes such as redistribution by wind, snow metamorphism and percolation of water, produce a complex spatial distribution of snow depths and snow densities. With its strong control on the ground thermal regime, this snow distribution has pronounced effects on ground temperatures at small spatial scales which are typically not resolved by land surface models (LSMs). This limits our ability to simulate the local impacts of climate change on for example vegetation and permafrost. Here, we present a tiling approach combining the CryoGrid permafrost model with snow microphysics parametrizations from the CROCUS snow scheme to account for sub‐grid lateral exchange of snow and water in a process‐based way. We demonstrate that a simple setup with three coupled tiles, each representing a different snow accumulation class with a specific topographic setting, can reproduce the observed spread of winter‐time ground surface temperatures (GST) and end‐of‐season snow distribution for a high‐Arctic site on Svalbard. For the three‐year study period, the three‐tile simulations showed substantial improvement compared to traditional single‐tile simulations which naturally cannot account for sub‐grid variability. Amongst others, the representation of the warmest and coldest 5% of the observed GST distribution was improved by 1‐2°C, while still capturing the average of the distribution. The simulations also reveal positive mean annual GSTs at the locations receiving the greatest snow cover. This could be an indication for the onset of localized permafrost degradation which would be obscured in single‐tile simulations.

Acquiring data to analyse change in topography is often a costly endeavour requiring either extensive, potentially risky, fieldwork and/or expensive equipment or commercial data. Bringing the cost down while keeping the precision and accuracy has been a focus in geoscience in recent years. Structure from motion (SfM) photogrammetric techniques are emerging as powerful tools for surveying, with modern algorithm and large computing power allowing for the production of accurate and detailed data from low-cost, informal surveys. The high spatial and temporal resolution permits the monitoring of geomorphological features undergoing relatively rapid change, such as glaciers, moraines, or landslides. We present a method that takes advantage of light-transport flights conducting other missions to opportunistically collect imagery for geomorphological analysis. We test and validate an approach in which we attach a consumer-grade camera and a simple code-based Global Navigation Satellite System (GNSS) receiver to a helicopter to collect data when the flight path covers an area of interest. Our method is based and builds upon Welty et al. (2013), showing the ability to link GNSS data to images without a complex physical or electronic link, even with imprecise camera clocks and irregular time lapses. As a proof of concept, we conducted two test surveys, in September 2014 and 2015, over the glacier Midtre Lovénbreen and its forefield, in northwestern Svalbard. We were able to derive elevation change estimates comparable to in situ mass balance stake measurements. The accuracy and precision of our DEMs allow detection and analysis of a number of processes in the proglacial area, including the presence of thermokarst and the evolution of water channels.

A research-based understanding of permafrost distribution at a sufficient spatial resolution is important to meet the demands of science, education and society. We present a new permafrost map for Norway, Sweden and Finland that provides a more detailed and updated description of permafrost distribution in this area than previously available. We implemented the CryoGRID1 model at 1km2 resolution, forced by a new operationally gridded data-set of daily air temperature and snow cover for Finland, Norway and Sweden. Hundred model realisations were run for each grid cell, based on statistical snow distributions, allowing for the representation of sub-grid variability of ground temperature. The new map indicates a total permafrost area (excluding palsas) of 23 400km2 in equilibrium with the average 1981-2010 climate, corresponding to 2.2 per cent of the total land area. About 56 per cent of the area is in Norway, 35 per cent in Sweden and 9 per cent in Finland. The model results are thoroughly evaluated, both quantitatively and qualitatively, as a collaboration project including permafrost experts in the three countries. Observed ground temperatures from 25 boreholes are within±2°C of the average modelled grid cell ground temperature, and all are within the range of the modelled ground temperature for the corresponding grid cell. Qualitative model evaluation by field investigators within the three countries shows that the map reproduces the observed lower altitudinal limits of mountain permafrost and the distribution of lowland permafrost. (Less)

The strong winds prevalent in high altitude and arctic environments heavily redistribute the snow cover, causing a small-scale pattern of highly variable snow depths. This has profound implications for the ground thermal regime, resulting in highly variable near-surface ground temperatures on the metre scale. Due to asymmetric snow distributions combined with the nonlinear insulating effect of snow, the spatial average ground temperature in a 1 km2 area cannot be determined based on the average snow cover for that area. Land surface or permafrost models employing a coarsely classified average snow depth will therefore not yield a realistic representation of ground temperatures. In this study we employ statistically derived snow distributions within 1 km2 grid cells as input to a regional permafrost model in order to represent sub-grid variability of ground temperatures. This improves the representation of both the average and the total range of ground temperatures. The model reproduces observed sub-grid ground temperature variations of up to 6 °C, and 98 % of borehole observations match the modelled temperature range. The mean modelled temperature of the grid cell reproduces the observations with an accuracy of 1.5 °C or better. The observed sub-grid variations in ground surface temperatures from two field sites are very well reproduced, with estimated fractions of sub-zero mean annual ground surface temperatures within ±10 %. We also find that snow distributions within areas of 1 km2 in Norwegian mountain environments are closer to a gamma than to a lognormal theoretical distribution. The modelled permafrost distribution seems to be more sensitive to the choice of distribution function than to the fine-tuning of the coefficient of variation. When incorporating the small-scale variation of snow, the modelled total permafrost area of mainland Norway is nearly twice as large compared to the area obtained with grid-cell average snow depths without a sub-grid approach.

Peat plateaus and palsas are characteristic morphologies of sporadic permafrost, and the transition from permafrost to permafrost‐free ground typically occurs on spatial scales of meters. They are particularly vulnerable to climate change and are currently degrading in Fennoscandia. Here we present a spatially distributed data set of ground surface temperatures for two peat plateau sites in northern Norway for the year 2015–2016. Based on these data and thermal modeling, we investigate how the snow depth and water balance modulate the climate signal in the ground. We find that mean annual ground surface temperatures are centered around 2 to 2.5 °C for stable permafrost locations and 3.5 to 4.5 °C for permafrost‐free locations. The surface freezing degree days are characterized by a noticeable threshold around 200 °C.day, with most permafrost‐free locations ranging below this value and most stable permafrost ones above it. Freezing degree day values are well correlated to the March snow cover, although some variability is observed and attributed to the ground moisture level. Indeed, a zero curtain effect is observed on temperature time series for saturated soils during winter, while drained peat plateaus show early freezing surface temperatures. Complementarily, modeling experiments allow identifying a drainage effect that can modify 1‐m ground temperatures by up to 2 °C between drained and water accumulating simulations for the same snow cover. This effect can set favorable or unfavorable conditions for permafrost stability under the same climate forcing.

In permafrost environments exposed to strong winds, drifting snow can create a small-scale pattern of strongly variable snow heights, which has profound implications for the thermal regime of the ground. Arrays of 26 to more than 100 temperature loggers were installed to record the distribution of ground surface temperatures within three study areas across a climatic gradient from continuous to sporadic permafrost in Norway. A variability of the mean annual ground surface temperature of up to 6°C was documented within areas of 0.5 km2. The observed variation can, to a large degree, be explained by variation in snow height. Permafrost models, employing averages of snow height for grid cells of, e.g., 1 km2, are not capable of representing such sub-grid variability. We propose a statistical representation of the sub-grid variability of ground surface temperatures and demonstrate that a simple equilibrium permafrost model can reproduce the temperature distribution within a grid cell based on the distribution of snow heights.

This study aims at quantifying the thermal response of mountain permafrost in southern Norway to changes in climate since 1860 and until 2100. A transient one-dimensional heat flow model was used to simulate ground temperatures and associated active layer thicknesses for nine borehole locations, which are located at different elevations and in substrates with different thermal properties. The model was forced by reconstructed air temperatures starting from 1860, which approximately coincides with the end of the Little Ice Age in the region. The impact of climate warming on mountain permafrost to 2100 is assessed by using downscaled air temperatures from a multi-model ensemble for the A1B scenario. Borehole records over three consecutive years of ground temperatures, air temperatures and snow cover data served for model calibration and validation. With an increase of air temperature of ~1.5 °C over 1860–2010 and an additional warming of ~2.8 °C until 2100, we simulate the evolution of ground temperatures for each borehole location. In 1860 the lower limit of permafrost was estimated to be ca. 200 m lower than observed today. According to the model, since the approximate end of the Little Ice Age, the active-layer thickness has increased by 0.5–5 m and >10 m for the sites Juvvasshøe and Tron, respectively. The most pronounced increases in active layer thickness were modelled for the last two decades since 1990 with increase rates of +2 cm yr−1 to +87 cm yr−1 (20–430%). According to the A1B climate scenario, degradation of mountain permafrost is suggested to occur throughout the 21st century at most of the sites below ca. 1800 m a.s.l. At the highest locations at 1900 m a.s.l., permafrost degradation is likely to occur with a probability of 55–75% by 2100. This implies that mountain permafrost in southern Norway is likely to be confined to the highest peaks in the western part of the country.

Steep permafrost rock walls marking the transition from high-lying plains to low-altitude fjord and valley systems are common in Norway. We have investigated the climate sensitivity of rock wall permafrost along a latitudinal transect from southern to northern Norway (60°N to 70°N) using topographic profiles from both natural sites and idealised sites with simplified geometries with steep rock walls bordering a flat plateau. We applied a two-dimensional ((2)D) transient thermal model (CryoGrid 2D) that includes both space- and time-dependent thermal parameters and the latent heat of ice-water phase transitions. The model has been forced using temperature data interpolated from meteorological observations between the end of the Little Ice Age and present warmer climatic conditions. We varied our model runs by changing the assumption of snow covers and applying glaciers at the plateaus. Our results show that the existence, geometry and thermal regime of the permafrost varies strongly depending on the snow and glacier cover on the plateau. Snow-free rock walls substantially govern the heat flow out of the rock wall, cooling the mountain interior below the plateau and favouring the development of permafrost beneath the margins of some plateaus. Copyright © 2015 John Wiley & Sons, Ltd.

Permafrost is a key element of the terrestrial cryosphere which makes mapping and monitoring of its state variables an imperative task. We present a modeling scheme based on remotely sensed land surface temperatures and reanalysis products from which mean annual ground temperatures (MAGT) can be derived at a spatial resolution of 1 km on continental scale. The approach explicitly accounts for the uncertainty due to unknown input parameters and their spatial variability at subgrid scale by delivering a range of MAGTs for each grid cell. This is achieved by a simple equilibrium model with only few input parameters which for each grid cell allows scanning the range of possible results by running many realizations with different parameters. The approach is applied to the unglacierized land areas in the North Atlantic region, an area of more than 5 million km2 ranging from the Ural mountains in the East to the Canadian Archipelago in the West. A comparison to in-situ temperature measurements in 143 boreholes suggests a model accuracy better than 2.5 °C, with 139 considered boreholes within this margin. The statistical approach with a large number of realizations facilitates estimating the probability of permafrost occurrence within a grid cell so that each grid cell can be classified as continuous, discontinuous and sporadic permafrost. At its southern margin in Scandinavia and Russia, the transition zone between permafrost and permafrost-free areas extends over several hundred km width with gradually decreasing permafrost probabilities. The study exemplifies the unexploited potential of remotely sensed data sets in permafrost mapping if they are employed in multi-sensor multi-source data fusion approaches.

Oversteepened valley walls in western Norway have high recurrences of Holocene rock-slope failure activity causing significant risk to communities and infrastructure. Deposits from six to nine catastrophic rock-slope failure (CRSF) events are preserved at the base of the Mannen rock-slope instability in the Romsdal Valley, western Norway. The timing of these CRSF events was determined by terrestrial cosmogenic nuclide dating and relative chronology due to mapping Quaternary deposits. The stratigraphical chronology indicates that three of the CRSF events occurred between 12 and 10 ka, during regional deglaciation. Congruent with previous investigations, these events are attributed to the debuttressing effect experienced by steep slopes following deglaciation, during a period of paraglacial relaxation. The remaining three to six CRSF events cluster at 4.9 ± 0.6 ka (based on 10 cosmogenic 10Be samples from boulders). CRSF events during this later period are ascribed to climatic changes at the end of the Holocene thermal optimum, including increased precipitation rates, high air temperatures and the associated degradation of permafrost in rock-slope faces. Geomorphological mapping and sedimentological analyses further permit the contextualisation of these deposits within the overall sequence of post-glacial fjord-valley infilling. In the light of contemporary climate change, the relationship between CRSF frequency, precipitation, air temperature and permafrost degradation may be of interest to others working or operating in comparable settings. © 2018. This is the authors' accepted and refereed manuscript to the article. The final authenticated version is available online at: https://journals.sagepub.com/doi/10.1177/0959683618798165

Accepted manuscript version. Published version available at https://doi.org/10.1177/0959683618798126. Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have been investigated through detailed analyses of plant macrofossils and geochemical properties. Peatland inception occurred around 9800 cal. yr BP and 9200 cal. yr BP at the two continental sites Suossjavri and Iskoras. Younger basal peat ages were found at the two coastal locations Lakselv and Karlebotn, at least partly caused by the time lag between deglaciation and emergence of land by isostatic uplift. Here, peatland development started around 6150 cal. yr BP and 5150 cal. yr BP, respectively. All four peatlands developed as wet fens throughout most of the Holocene. Permafrost aggradation, causing frost heave and a shift in the vegetation assemblage from wet fen to dry bog species, probably did not occur until during the last millennium, ca. 950 cal. yr BP in Karlebotn and ca. 800 cal. yr BP in Iskoras, and before ca. 150 cal. yr BP in Lakselv and ca. 100 cal. yr BP in Suossjavri. In Karlebotn, there are indications of a possible earlier permafrost phase around 2200 cal. yr BP due to climatic cooling at the late Subboreal to early Subatlantic transition. The mean long-term Holocene carbon accumulation rate at all four sites was 12.3 +/- 4.1 gC m-2 yr-1 (+/- SD) and the mean soil organic carbon storage was 97 +/- 46 kgC m-2.

Two methods for digital mapping and analysis of topographic surfaces of moderate relief, such as erosional surfaces, are introduced and discussed in this paper. The surface fit method uses least squares to solve the problem of finding the best surface fit to the data, whereas the region grow method uses the surface slope and a set of properties (e.g. maximum slope between adjacent pixels) to generate surfaces from single seed GPS-positions. In both methods the analysed surface was identified from field controlled geological maps. The surface fit method is applicable to landscapes with great topographic varieties, whereas the region grow method is most applicable to relatively flat areas. Both methods were used to identify the sub-Cambrian peneplain (SCP). The result suggests that the SCP occurs across significant parts of the Hardangervidda area, with a greater lateral extent in the central part of the area compared to the northern part. This can be attributed to more extensive faulting of the SCP in the northern part.

Extrapolation potential of statistically-based geomorphological distribution models (GDMs) has not been scrutinized. Here, the possibility to transfer solifluction models within and between six study areas in subarctic and Arctic environments was examined. A generalized linear model, generalized additive model, maximum entropy and boosted regression tree methods were used in the analyses. The transferability success of the GDMs was assessed by the area under the curve of a receiver operating characteristic plot. Based on the results, slope angle, mean annual air temperature and a remote sensing based index of vegetation abundance were the most important variables contributing to the occurrence of solifluction at a landscape scale. In model extrapolation, over half of the calibrated solifluction models were transferable from one area to another. The topographical conditions of the study areas had a greater effect than climate conditions on the extrapolation potential. More precisely, it was more difficult to extrapolate the models to a high-relief environment than to an area with moderate topography. On the contrary, the models transferred within Arctic and subarctic areas were not better than the models between the Arctic and subarctic environments. In conclusion, (i) region specific geomorphological and environmental conditions may significantly affect the relative importance of variables in GDMs, (ii) solifluction models were transferable with certain limitations across areas, (iii) the range of the environmental conditions of the calibration area was a critical factor for transferability success and (iv) machine learning-based methods performed marginally better than parametric models in the model extrapolation. Extensive knowledge about the transferability of GDMs in space is needed before the models can be reliably used in climate change explorations.

The warming and degradation of mountain permafrost within alpine areas is an important process influencing the stability of steep slopes and rock faces. In the mountains of southern Norway (Jotunheimen), an increase in ground temperatures has been recorded during the last 12 years, and modelling studies suggest the possible degradation of most mountain permafrost during the 21st century. To better estimate the thermal state of permafrost in steep rock walls in Norway, five temperature loggers were installed in 2009 and 2010, measuring the near-surface rock wall temperatures in vertical rock faces. Surface temperatures in rock walls in Norway are on average higher than the ambient air temperature, by about 1 °C in shaded faces to more than 3 °C in faces with other aspects. An aspect dependency of rock wall temperatures is mainly visible during summer, with deviations of up to 4 °C between north- and south-facing walls. Based on a 1D transient heat flow model, the active-layer thickness at the study sites was estimated to be in the range of 3 m to 5 m at 2300 m asl and 1600 m asl, respectively. As a first-order approximation, a spatial regression model based on elevation and potential incoming short-wave radiation was used to estimate the lower limit and distribution of rock wall permafrost under present-day conditions and for a scenario with average air temperatures increased by 2 °C. Today, the lower limit ranges from 1200–1300 m asl to 1600–1700 m asl in north- and south-facing rock walls, respectively. With a warming of 2 °C, the lower limit would increase to about 1700 m and 2100 m, respectively, which corresponds to a loss of 70 per cent of the rock walls underlain by permafrost today in the study area, where more than half of the rock walls potentially containing permafrost are situated below 1800 m asl. Copyright © 2014 John Wiley & Sons, Ltd.

Knowledge of the characteristics and spatial distribution of permafrost in Iceland is important to understanding slope stability, climate change impacts and palaeo-glaciology. The permafrost distribution there, however, is poorly constrained. The presence of rock glaciers and stable ice-cored moraines in mountain settings relates to permafrost, making such landforms indicators of present or past permafrost. This study combines recently published aerial photographs (2002–07), radar interferometry based on Advanced Land Observing Satellite phased array type L-band synthetic aperture radar (ALOS PALSAR) data (2007), land surface temperatures estimated from moderate-resolution imaging spectroradiometer satellite data (MODIS; 2003–10) and field mapping to re-examine the permafrost distribution, thermal characteristics and dynamics on the Trollaskagi peninsula. An inventory of 265 landforms, mostly active or inactive (intact), categorised them by genesis and activity, the latter independently investigated by PALSAR interferometry. Intact landforms are mainly glacigenic, occurring as moraine-derived rock glaciers or ice-cored moraines. Their dominant orientation is between north and northeast, suggesting that topography and exposure influence their present-day formation. Permafrost landforms exist at all elevations on the Trollaskagi peninsula, with intact landforms at high elevations and relict landforms reaching down to sea level. Rock glaciers at sea level may imply early deglaciation of northern Iceland. Copyright © 2013 John Wiley & Sons, Ltd.

Knowledge of the thermal state of mountain permafrost has greatly increased since 2007 with the establishment of numerous new monitoring stations around the world. Data collected at these sites have pointed to longer-term changes in ground temperatures, which seem to have increased during the last two to three decades in cold permafrost, while in ground close to 0°C the near-surface ice content has restricted warming and similar trends are not apparent. Modelling of mountain permafrost has developed greatly, driven by general circulation models or gridded temperature maps, through both predictive methods and spatial equilibrium and transient approaches. The spatial resolution of climate parameters, which is normally much coarser than the spatial heterogeneity of alpine environments, presents a major problem for modelling studies. This is a fundamental challenge for future research. Copyright © 2013 John Wiley & Sons, Ltd.

Omnsbreen is a small (2) and degrading glacier situated at the regional lower limit of present-day permafrost distribution and glaciation. At present, the existence of Omnsbreen is mainly dependent on wind-borne snow redistributed by the prevailing westerly winter-wind, and lies in an area of marginal permafrost occurrence. During the ‘Little Ice Age’ (LIA) both the glacier and the distribution of permafrost in the area reached their maximum late-Holocene areal extents. The first occurrence of Omnsbreen is recorded in sediment cores retrieved from a proglacial lake and dated at ad 1425, and marks the onset of the local LIA. Reconstruction of the maximum LIA extent by means of geomorphic indicators revealed a size of 7.1 km2, a volume of more than 0.25 km3 and a maximum glacier thickness of 110 m. Since the LIA Omnsbreen has been reduced by more than 90% in area. Omnsbreen retreated rapidly from its LIA maximum, which we suggest was determined by the shape of the glacier, filling up the valley, and hence being unable to accumulate wind-borne snow. Prominent glacier marginal landforms are absent along the maximum LIA extent of Omnsbreen. We propose that the lack of glacier marginal landforms in this case is indicative of a cold glacier margin, and that the landscape evolution in maritime and marginal permafrost regions is characterised as being closely connected with glacial activity.

Since 2002, ground and ground surface temperatures have been systematically measured in the mountains of Troms and Finnmark, northern Norway. These data were used to calibrate and validate a transient heat flow model and a spatial permafrost model, to address ground thermal development since the end of the Little Ice Age, as well as possible permafrost responses to anticipated future climate changes. Approximately 20 per cent of the land area is underlain by permafrost, and in Finnmark, permafrost in palsa mires seems to dominate. Both observations and modelling show that the present permafrost is mainly ‘warm’, with mean ground temperatures above -3 °C. Permafrost has warmed during the last century, and at one site our ground temperature observations show the degradation of permafrost over the intervening decade. The study identifies three major permafrost regions in northern Norway: (1) maritime mountain permafrost in western Troms; (2) continental permafrost above the treeline and in bogs in Finnmark; and (3) Low Arctic permafrost on the peninsula of Varangerhalvoya, forming a transition between the Scandinavian mountain-dominated permafrost in the south and the arctic permafrost towards the north and east. Copyright © 2013 John Wiley & Sons, Ltd.

CryoGRID 1.0 provides an equilibrium model of permafrost distribution in Norway at a spatial resolution of 1 km2. The approach was forced with gridded data on daily air temperature and snow cover. Ground thermal properties for different bedrock types and sediment covers were derived from surveys and geological maps to yield distributions of thermal conductivity, heat capacity and water content. The distribution of blockfields was derived from satellite images adapting a newly developed classification scheme. The model was evaluated using measured ground surface and ground temperatures, yielding a realistic description of the permafrost distribution in mainland Norway. The model results show that permafrost underlies sites mainly with exposed bedrock or covered by coarse-grained sediments, such as blockfields and coarse tills. In northern Norway, palsa mires are abundant and organic material and vegetation strongly influence the ground thermal regime. Modelling suggests that permafrost in equilibrium with the 1981–2010 climate presently underlies between 6.1 per cent and 6.4 per cent of the total area of mainland Norway, an area significantly smaller than that modelled for the Little Ice Age climate (14%). CryoGRID 1.0 was subsequently forced using output from a regional climate model for the 2071–2100 period, which suggests that severe permafrost degradation will occur, leaving permafrost beneath an area of just 0.2 per cent of mainland Norway. Copyright © 2013 John Wiley & Sons, Ltd.

Permafrost is a sensitive element of the cryosphere, but operational monitoring of the ground thermal conditions on large spatial scales is still lacking. Here, we demonstrate a remote-sensing-based scheme that is capable of estimating the transient evolution of ground temperatures and active layer thickness by means of the ground thermal model CryoGrid 2. The scheme is applied to an area of approximately 16 000 km2 in the Lena River delta (LRD) in NE Siberia for a period of 14 years. The forcing data sets at 1 km spatial and weekly temporal resolution are synthesized from satellite products and fields of meteorological variables from the ERA-Interim reanalysis. To assign spatially distributed ground thermal properties, a stratigraphic classification based on geomorphological observations and mapping is constructed, which accounts for the large-scale patterns of sediment types, ground ice and surface properties in the Lena River delta. A comparison of the model forcing to in situ measurements on Samoylov Island in the southern part of the study area yields an acceptable agreement for the purpose of ground thermal modeling, for surface temperature, snow depth, and timing of the onset and termination of the winter snow cover. The model results are compared to observations of ground temperatures and thaw depths at nine sites in the Lena River delta, suggesting that thaw depths are in most cases reproduced to within 0.1 m or less and multi-year averages of ground temperatures within 1–2 °C. Comparison of monthly average temperatures at depths of 2–3 m in five boreholes yielded an RMSE of 1.1 °C and a bias of −0.9 °C for the model results. The highest ground temperatures are calculated for grid cells close to the main river channels in the south as well as areas with sandy sediments and low organic and ice contents in the central delta, where also the largest thaw depths occur. On the other hand, the lowest temperatures are modeled for the eastern part, which is an area with low surface temperatures and snow depths. The lowest thaw depths are modeled for Yedoma permafrost featuring very high ground ice and soil organic contents in the southern parts of the delta. The comparison to in situ observations indicates that transient ground temperature modeling forced by remote-sensing data is generally capable of estimating the thermal state of permafrost (TSP) and its time evolution in the Lena River delta. The approach could hence be a first step towards remote detection of ground thermal conditions and active layer thickness in permafrost areas.

Seven sites within the mountain region of Abisko, northern Sweden, were selected for measurement of solifluction movement rates and correlation with the local environmental factors. Grids with size ...

A ten-year record (1999–2009) of annual mean ground surface temperatures (MGSTs) and mean ground temperatures (MGTs) was analysed for 16 monitoring sites in Jotunheimen and on Dovrefjell, southern Norway. Warming has occurred at sites with cold permafrost, marginal permafrost and deep seasonal frost. Ongoing permafrost degradation is suggested both by direct temperature monitoring and indirect geophysical surveys. An increase in MGT at 6.6–9.0-m depth was observed for most sites, ranging from ~0.015 to ~ 0.095°C a-1. The greatest rate of temperature increase was for sites having MGTs slightly above 0°C. The lowest rate of increase was for marginal permafrost sites that are affected by latent heat exchange close to 0°C. Increased snow depths and an increase in winter air temperatures appear to be the most important factors controlling warming observed over the ten-year period. Geophysical surveys performed in 1999 to delineate the altitudinal limit of mountain permafrost were repeated in 2009 and 2010 and indicated the degradation of some permafrost over the intervening decade. Copyright © 2011 John Wiley & Sons, Ltd.

In this study, we present field measurements and numerical process modeling from western Svalbard showing that the ground surface temperature below the snow is impacted by strong wintertime rain events. During such events, rain water percolates to the bottom of the snow pack, where it freezes and releases latent heat. In the winter season 2005/2006, on the order of 20 to 50% of the wintertime precipitation fell as rain, thus confining the surface temperature to close to 0 °C for several weeks. The measured average ground surface temperature during the snow-covered period is −0.6 °C, despite of a snow surface temperature of on average −8.5 °C. For the considered period, the temperature threshold below which permafrost is sustainable on long timescales is exceeded. We present a simplified model of rain water infiltration in the snow coupled to a transient permafrost model. While small amounts of rain have only minor impact on the ground surface temperature, strong rain events have a long-lasting impact. We show that consecutively applying the conditions encountered in the winter season 2005/2006 results in the formation of an unfrozen zone in the soil after three to five years, depending on the prescribed soil properties. If water infiltration in the snow is disabled in the model, more time is required for the permafrost to reach a similar state of degradation.

Warm permafrost conditions (mean temperatures of −3°C to −0.1°C) were investigated in detail at 13 valley and mountain sites in the sporadic (10–50%) and extensive (50–90%) discontinuous permafrost zones in the southern half of the Yukon (60°N to 64°N), using a combination of ground temperature monitoring, electrical resistivity tomography (ERT), frost table probing and coring. Sites were selected to cover a wide range of substrates, vegetation types and ground ice contents. ERT profiling in the spring imaged both deep seasonal frost and perennially frozen ground. Deep active layers measured by probing at the end of summer were also detectable by ERT. Where ground temperatures indicated that the base of permafrost was at a depth of less than 25 m, vertical transitions in apparent resistivity were more sharply defined in coarse materials than in fine-grained deposits, probably because of differences in unfrozen moisture contents at temperatures just below 0°C. Apparent resistivity values related to excess ice fraction and ground temperatures were similar to those previously obtained in Mongolia and Iceland, but generally lower than in ice-rich rock glaciers in European studies. The observations revealed the complexity of site conditions where permafrost is discontinuous and the utility of ERT, in combination with other methods, to investigate permafrost thickness, spatial extent and ice content for infrastructure planning or climate change studies. Copyright © 2011 John Wiley & Sons, Ltd.

Recent accounts suggest that periglacial processes are unimportant for large-scale landscape evolution and that true large-scale periglacial landscapes are rare or non-existent. The lack of a large-scale topographical fingerprint due to periglacial processes may be considered of little relevance, as linear process–landscape development relationships rarely can be substantiated. Instead, periglacial landscapes may be classified in terms of specific landform associations. We propose “cryo-conditioning”, defined asthe interaction of cryotic surface and subsurface thermal regimes and geomorphic processes, as an overarching concept linking landform and landscape evolution in cold regions. By focusing on the controls on processes, this concept circumvents scaling problems in interpreting long-term landscape evolution derived from short-term processes. It also contributes to an unambiguous conceptualization of periglacial geomorphology. We propose that the development of several key elements in the Norwegian geomorphic landscape can be explained in terms of cryo-conditioning.

Variations in ground thermal conditions in Svalbard were studied based on measurements and modelling. Ground temperature data from boreholes were used to calibrate a transient heat flow model describing depth and time variations in temperatures. The model was subsequently forced with historical surface air temperature records and possible future temperatures downscaled from multiple global climate models. We discuss ground temperature development since the early 20th century, and the thermal responses in relation to ground characteristics and snow cover. The modelled ground temperatures show a gradual increase between 1912 and 2010, by about 1.5 °C to 2 °C at 20 m depth. The active layer thickness (ALT) is modelled to have increased slightly, with the rate of increase depending on water content of the near-surface layers. The used scenario runs predict a significant increase in ground temperatures and an increase of ALT depending on soil characteristics.

The effects of scale (modelling resolution) and sources of data were explored in relation to periglacial distribution modelling for an area on western Svalbard in the High Arctic. To assess the effects of scale on predictive performance, the distributions of sorted circles and solifluction lobes were modelled at two resolutions (20 × 20 m and 200 × 200 m) using a boosted regression tree, a novel statistical ensemble method. To analyse the effects of sources of data on periglacial distribution modelling, a generalised linear model and a variation partitioning method were used. The explanatory variables were topographic parameters computed from a digital elevation model, vegetation and soil moisture indices derived from a Landsat TM 5 scene, and field survey-based information on surficial materials. Firstly, similar levels of success were achieved in predicting the periglacial feature distributions at the local (20 m) and landscape (200 m) scales. Secondly, results indicated the potential for modelling to replace labour-intensive field observations. The importance of topographic parameters for predicting the distribution of periglacial features in the sparsely vegetated High Arctic environment was also evident. Methodologically, novel statistical techniques and earth observation data provided an efficient combination for analysing periglacial landforms and processes in this remote region. Copyright © 2010 John Wiley & Sons, Ltd.

The occurrence of turf-banked solifluction landforms in the Abisko region was analysed using a grid-based approach and statistical modelling through logistic regression. Significant parameters in t ...

This paper provides a snapshot of the permafrost thermal state in the Nordic area obtained during the International Polar Year (IPY) 2007-2009. Several intensive research campaigns were undertaken within a variety of projects in the Nordic countries to obtain this snapshot. We demonstrate for Scandinavia that both lowland permafrost in palsas and peat plateaus, and large areas of permafrost in the mountains are at temperatures close to 0 degrees C, which makes them sensitive to climatic changes. In Svalbard and northeast Greenland, and also in the highest parts of the mountains in the rest of the Nordic area, the permafrost is somewhat colder, but still only a few degrees below the freezing point. The observations presented from the network of boreholes, more than half of which were established during the IPY, provide an important baseline to assess how future predicted climatic changes may affect the permafrost thermal state in the Nordic area. Time series of active-layer thickness and permafrost temperature conditions in the Nordic area, which are generally only 10 years in length, show generally increasing active-layer depths and risings permafrost temperatures. Copyright (C) 2010 John Wiley & Sons, Ltd. (Less)

The main objectives of this study were to model the relationship between WRB-1998 soil groups and terrain attributes and predict the spatial distribution of the soil groups using digital terrain analysis and multinomial logistic regression integrated in GIS in the Vestfold County of south-eastern Norway. A digital elevation model of 25 meter grid resolution was used to derive fifteen terrain attributes. A digitized soil map of thirteen WRB soil groups at the scale of 1:25,000 was used to obtain the reference soil data for model building and validation. First, the relationships between the soil groups and the terrain attributes were modeled using multinomial logistic regression. Then, the probability that a given soil type is present at a given pixel was determined from the logit models in ARCGIS to continuously map each soil group's spatial distribution. Elevation, flow length, duration of daily direct solar radiation, slope, aspect and topographic wetness index were found to be the most significant terrain attributes correlating with the spatial distribution of the soil groups. The prediction showed higher mean probability values for each soil group in the areas actually covered by that soil group compared to other areas, indicating the reliability of the prediction. However, the prediction performed poorly for soil groups that are not greatly influenced by topography but by other factors such as human activities.

The distribution of mountain permafrost in the northern hemisphere depends on topographic and climatic factors, ranging from the maritime conditions of Iceland over transitional conditions in southern Norway to continental conditions in Mongolia, and from alpine mountains to paleic mountains. This study discusses the different environmental factors that govern permafrost distribution based on personal studies and a literature review. It is hypothesized that the thermal state of the ground is an important parameter to understand the time and spatial scale of sediment transfer and landscape development in cold mountainous regions. This is exemplified for the cases of rock walls, glacier forefields, rock glaciers, and the case of sediment remobilization due to glacier advance. The authors propose that thorough knowledge of the ground thermal regime is an important basis for addressing sediment budgets in space and time.

This paper provides a review of permafrost modelling advances, primarily since the 2003 permafrost conference in Zurich, Switzerland, with an emphasis on spatial permafrost models, in both arctic and high mountain environments. Models are categorised according to temporal, thermal and spatial criteria, and their approach to defining the relationship between climate, site surface conditions and permafrost status. The most significant recent advances include the expanding application of permafrost thermal models within spatial models, application of transient numerical thermal models within spatial models and incorporation of permafrost directly within global circulation model (GCM) land surface schemes. Future challenges for permafrost modelling will include establishing the appropriate level of integration required for accurate simulation of permafrost-climate interaction within GCMs, the integration of environmental change such as treeline migration into permafrost response to climate change projections, and para- meterising the effects of sub-grid scale variability in surface processes and properties on small-scale (large area) spatial models. Copyright # 2008 John Wiley & Sons, Ltd.

A regional map of permafrost distribution in Iceland was developed based on meteorological data. The regional model was calibrated with ground surface temperature data and tested using ground temperature data from four shallow boreholes and a rock glacier inventory. The results indicate widespread mountain permafrost at elevations above 800–900 m a.s.l. in northern and eastern Iceland. According to the regional map, the mountain permafrost zone covers c. 8000 km2 which is about 8% of the country's land area. Copyright © 2007 John Wiley & Sons, Ltd.

The relationship between explosive volcanic eruptions and permafrost aggradation is discussed at a regional (Hekla volcano, Iceland, 63°59′N 19°40′W) and a global scale. During the most recent Hekla eruption in winter 2000, tephra buried the adjacent winter snow cover. Observations of denivation landforms, excavated sections and active-layer thickness were carried out 15 to 77 months after the eruption. Results show that the combination of climate that favours permafrost and a thin layer of tephra is sufficient to reduce the sub-tephra snow ablation substantially, possibly even to zero, causing aggradation of the surface and preserving massive ground ice and permafrost. Based on these observations, a conceptual model for permafrost aggradation related to tephra accumulation was developed. On a global scale, about one third of all active volcanoes seems to be located in permafrost-favourable areas, suggesting that explosive volcanic eruptions may be significant for permafrost aggradation. Copyright © 2007 John Wiley & Sons, Ltd.

In this study three areas of different active, coarse-debris, slope processes are investigated in Northern and Eastern Iceland. Surface displacement of some glacier-derived rock glaciers and a debris-covered glacier in the Holar area, a moving debris accumulation close to Siglufjorður and a debris layer in Seyðisfjorður are measured. The displacement fields are obtained by cross-correlation matching of multi-temporal orthophotos. Orthophotos are generated using a Z/I-Imaging digital photogrammetric workstation and various series of air photos from 1964 to 1994. Cross-correlation matching is done with the CIAS software. The results are analyzed and used for rough surface age estimates. In addition, type and cause of movement are discussed. The velocity of the debris-covered glacier and the rock glaciers in the Holar area averages from 0.14 to 0.67 m a− 1. The debris accumulation at Almenningsnof close to Siglufjorður shows an average displacement of 0.19 m a− 1 with a maximum value of 0.84 m a− 1. The displacements at Almenningsnof agree well with displacements surveyed by GPS by the Icelandic road authorities. The measured velocities in Seyðisfjorður, although using air photos taken 30 years apart, turned out not to be significant, but the homogenous direction of the displacement vectors suggests that the debris is currently creeping. Based on the surface age results all the landforms in Holar are suggested to have developed during the late-Holocene cooling period, with ages from around 1500 and 3000 to around 5000 years for the different landforms. These surface age estimates coincide with data from moraine datings nearby and Holocene climatic development in the North Atlantic region.

Lake Hovsgol is located on the southern fringe of the continuous permafrost zone in northern Mongolia. This paper describes a GIS-based empirical permafrost model that is calibrated with ground temperature observations, and utilises a multi-criteria approach to derive zones of permafrost favourability based on terrain parameters and land cover information. The scores are derived either by logistic regression or from satellite image information. The model is validated by DC resistivity tomography measurements. The overall permafrost distribution in the study area is well-described and the method appears to be a valid approach for mapping permafrost at both local and regional scales in mountain areas with low data coverage. Copyright © 2006 John Wiley & Sons, Ltd.

Near-surface temperature variations in different topographic settings were obtained from miniature temperature data-loggers at 17 locations over a 2-year period in the Lake Hovsgol area in northern Mongolia. These measurements were used to analyse the influence of vegetation, solar radiation, surface wetness and snow cover on the ground thermal regime. An empirical modelling approach was applied in order to estimate the spatial distribution of ground surface temperatures, the presence of permafrost and the depth of the active layer. Our study shows that spatial interpolation of ground surface temperature parameters, mainly known from previous research in the Arctic, can be feasible in the arid mountain environments of Central Asia. Copyright © 2006 John Wiley & Sons, Ltd.

This review paper aims at discussing aspects and concepts of the significance of the spatial and temporal distribution of permafrost on glacial and gravitational processes in southern Norway. The study first reviews the distribution of mountain permafrost in southern Norway in comparison with high-relief alpine areas like the Alps, and then discusses the influence of permafrost on gravitational and glacial–geomorphological processes. The basis for the paper is a regional-scale distribution model of mountain permafrost in southern Norway, which is analysed in relation to topographic variations within the same area. The model allows a crude extrapolation to past and future permafrost distribution, which is discussed in relation to geomorphic processes.

European mountain permafrost is generally only a few degrees below zero Celsius, and may therefore be highly sensitive to climate change. Permafrost degradation may lead to thaw settlement and reduction in the stability of mountain slopes. Engineering projects within the high mountain zone require careful investigations of potential permafrost-related hazards. This paper summarizes a staged approach to such investigations. Phase 1 involves walkover site survey supported by a desk study to define potential permafrost hazard zones. Data from permafrost distribution maps, topographic and geological maps are integrated, preferably using GIS methodology. If permafrost is possible and is judged to pose a significant threat to the development, phase 2 investigations are recommended whereby field thermal measurements, drilling of exploratory boreholes, and geophysical surveys are undertaken to clarify permafrost characteristics. The resulting data set should form an important component in subsequent engineering design. On a larger scale, a similar approach should be adopted as part of land-use planning within the mountain permafrost zone. Copyright © 2001 John Wiley & Sons, Ltd. RESUME Generalement, le pergelisol europeen de montagne est seulement quelques degres en dessous du zero Celsius et est, de ce fait, tres sensible aux changements climatiques. La degradation du pergelisol peut entrainer des affaissements du sol au degel et une reduction de la stabilite des pentes de montagne. Des projets d'ingenierie dans la haute montagne exigent donc des recherches soigneuses concernant les risques potentiels lies a l'existence du pergelisol. Le present article resume une approche en differentes etapes d'une telle recherche. La phase 1 consiste en un examen attentif du terrain, travail suivi par une etude en laboratoire afin de definir les zones potentielles ou existerait un pergelisol dangereux. Des donnees provenant de cartes de la distribution du pergelisol ainsi que de cartes topographiques et geologiques doivent etre integrees en utilisant si possible un systeme d'information geographique. Si un pergelisol est possible et parait constituer une menace, une deuxieme phase de recherches est recommandee. Elle comprendra des mesures de temperature sur le terrain, la realisation de forages d'exploration et des leves geophysiques pour definir les caracteristiques du pergelisol. Les donnees recueillies constitueront une partie importante du projet d'ingenierie. A une echelle plus grande, une approche semblable devrait etre adoptee dans toute etude visant a modifier l'affectation de terrains dans la zone du pergelisol de montagne. Copyright © 2001 John Wiley & Sons, Ltd.

In recent years successful attempts have been made to develop and improve spatial modelling of mountain permafrost distribution. Work package 4 of the PACE project (Permafrost and Climate in Europe) sought to provide the essential basis not only of present-day modelling capability, but also of future enhancements in modelling methodology. This paper briefly outlines the currently available typology of models, which involve various levels of sophistication at different spatio-temporal scales. Appropriate models may be applied to a range of environmental issues in cold mountain areas, including engineering applications, climate-change scenarios, large-scale mapping, studies of surface processes or environmental concerns. Special emphasis is given here to aspects of energy exchange at the surface and within the active layer. Such energy fluxes remain poorly understood but play an essential role in process-oriented research and sensitivity studies with respect to complex interactions and feedbacks within the system. In contrast to relatively flat permafrost areas in polar and subpolar lowlands, circulation of water and air can cause important lateral fluxes of matter and energy within coarse blocks on steep slopes and result in highly variable and sometimes extreme thermal offsets between the ground surface and the permafrost table. Measuring and numerically modelling such fluxes together with coupling time-dependent surface and subsurface ground thermal conditions in characteristic materials (bedrock, ice-rich debris, fine-grained deposits) constitute the main challenge for research in the near future. Copyright  2001 John Wiley & Sons, Ltd. R ´

Alpine permafrost and frost-related geomorphological processes are sensitive to climatic change. Thus, there is an increasing demand for permafrost maps in high-alpine environments. The objective of this paper is to present the application of terrain analysis and classification based on digital elevation models (DEMs) together with remotely sensed data (e.g. Landsat TM) in mapping of permafrost and slope activity as a supplement to existing methods. The study reviews principles and recent developments in this field, and presents three different approaches in the form of case studies from mountain areas of southern Norway. Copyright © 2001 John Wiley & Sons, Ltd. RESUME Le pergelisol alpin et les processus geomorphologiques dus au gel sont sensibles aux changements de climat. II y a, en consequence, une demande accrue de cartes du pergelisol dans les environnements de hautes altitudes. L'objectif de cet article est de presenter comment l'analyse du terrain et une classification du sol basee sur des modeles d'altitude, combinees avec l'utilisation de donnees de teledetection (Landsat TM), peuvent servir a cartographier le pergelisol et l'activite geomorphologique sur les versants, et constituer un supplement aux methodes deja existantes. L'etude passe en revue les principes et les developpements recents dans ce domaine et presente trois differentes approches dans des etudes de cas de regions montagneuses de Norvege meridionale. Copyright © 2001 John Wiley & Sons, Ltd.

Finsterwalderbreen (77°26’ N, 15° 15’ E) is a 35 km2 polythermal, surge-type glacier in southern Spitsbergen, Svalbard. Extensive field investigations have been carried out on the glacier, including mapping of bed topography by radio-echo soundings, mass-balance measurements and hydrological and meteorological registrations. In this paper we have used surface and bed topography and observations of summer ablation to estimate total runoff and subglacial drainage pattern by means of spatial map analysis in standard geographic information system software. The location and relative importance of the water-channel outlets from the glacier were estimated, as well as the change in drainage pattern over the period 1970–90. The results could be compared to direct observations of drainage pattern and discharge recordings. The analyses indicate that the location of the subglacial channels is dominated by the surface topography and thus that the channels are partly pressurized.

Rock glacier structure, velocity and morphology were studied on the island of Prins Karls Forland, western Svalbard (78°50′N, 10°30′E). On the north-western part of the island, lobate rock glaciers build a 10 km long continuous transition between rockwall and strandflat area. In this area, a high-resolution digital elevation model (DEM) was constructed, and surface velocity measurements and DC resistivity soundings were carried out on selected rock glaciers. The conceptual model of Haeberli and Vonder Muhll is discussed for high arctic areas, where the permafrost base is beneath the base of the rock glaciers. © 1998 John Wiley & Sons, Ltd. La structure, la vitesse et la morphologie des glaciers rocheux ont ete etudiees sur l'ile Prins Karls Forland, dans le Svalbard occidental (78°50′N, 10°30′E). Dans la partie nord-ouest de l'ile, des glaciers rocheux lobes constituent une transition continue de 10 km de longueur entre la falaise rocheuse et la plate-forme marine. Dans cette zone, un modele de relief digital a haute resolution a ete etabli, et des mesures de vitesse de surface ainsi que des sondages par resistivite ont ete realises sur certains glaciers rocheux. Le modele conceptuel de Haeberli et Vonder Muhl (1996) est discute dans son application a des regions du haut Arctique ou la base du pergelisol se trouve sous la base du glacier rocheux. © 1998 John Wiley & Sons, Ltd.

The Norwegian traffic network is impacted by about 2000 landslides, avalanches, and debris flows each year that incur high economic losses. Despite the urgent need to mitigate future losses, efforts to locate potential debris flow source areas have been rare at the regional scale. We tackle this research gap by exploring a minimal set of possible topographic predictors of debris flow initiation that we input to a Weights-of-Evidence (WofE) model for mapping the regional susceptibility to debris flows in western Norway. We use an inventory of 429 debris flows that were recorded between 1979 and 2008, and use the terrain variables of slope, total curvature, and contributing area (flow accumulation) to compute the posterior probabilities of local debris flow occurrence. The novelty of our approach is that we quantify the uncertainties in the WofE approach arising from different predictor classification schemes and data input, while estimating model accuracy and predictive performance from independent test data. Our results show that a percentile-based classification scheme excels over a manual classification of the predictor variables because differing abundances in manually defined bins reduce the reliability of the conditional independence tests, a key, and often neglected, prerequisite for the WofE method. The conditional dependence between total curvature and flow accumulation precludes their joint use in the model. Slope gradient has the highest true positive rate (88%), although the fraction of area classified as susceptible is very large (37%). The predictive performance, i.e. the reduction of false positives, is improved when combined with either total curvature or flow accumulation. Bootstrapping shows that the combination of slope and flow accumulation provides more reliable predictions than the combination of slope and total curvature, and helps refining the use of slope–area plots for identifying morphometric fingerprints of debris flow source areas, an approach used outside the field of landslide susceptibility assessments.

This paper presents an approach to long-term glacier monitoring. Mathematical surface descriptors, such as altitude, slope and curvature (surface form) are used to classify and quantify glacier surface developments. The analysis is based on photogrammetically derived grid-based digital elevation models over a period of decades. This paper outlines the concept and applies it to five valley glaciers in Spitsbergen, Svalbard, which differ with respect to size, thermal regime and dynamics. The results reflect differences between the glaciers investigated which are attributable to glacier dynamics, in particular concerning the glacier’s possible surge behaviour during a period with retreat and mass losses.