scholarly journals Warming permafrost and active layer variability at Cime Bianche, Western Alps

2014 ◽  
Vol 8 (4) ◽  
pp. 4033-4074
Author(s):  
P. Pogliotti ◽  
M. Guglielmin ◽  
E. Cremonese ◽  
U. Morra di Cella ◽  
G. Filippa ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Snow Cover ◽  
Layer Thickness ◽  
Active Layer ◽  
Ground Surface ◽  
Small Scale ◽  
Active Layer Thickness ◽  
Spatial And Temporal Variability ◽  
Monitoring Site ◽  
Surface Temperatures

Abstract. The objective of this paper is to provide a first synthesis on the state and recent evolution of permafrost at the monitoring site of Cime Bianche (3100 m a.s.l.). The analysis is based on seven years of ground temperatures observations in two boreholes and seven surface points. The analysis aims to quantify the spatial and temporal variability of ground surface temperatures in relation to snow cover, the small scale spatial variability of the active layer thickness and the warming trends on deep permafrost temperatures. Results show that the heterogeneity of snow cover thickness, both in space and time, is the main factor controlling ground surface temperatures and leads to a mean range of spatial variability (2.5±0.15°C) which far exceeds the mean range of observed inter-annual variability (1.6±0.12°C). The active layer thickness measured in two boreholes 30 m apart, shows a mean difference of 2.03±0.15 m with the active layer of one borehole consistently lower. As revealed by temperature analysis and geophysical soundings, such a difference is mainly driven by the ice/water content in the sub-surface and not by the snow cover regimes. The analysis of deep temperature time series reveals that permafrost is warming. The detected linear trends are statistically significant starting from depth below 8 m, span the range 0.1–0.01°C year−1 and decrease exponentially with depth. Our findings are discussed in the context of the existing literature.

scholarly journals Warming permafrost and active layer variability at Cime Bianche, Western European Alps

2015 ◽  
Vol 9 (2) ◽  
pp. 647-661 ◽  
Author(s):  
P. Pogliotti ◽  
M. Guglielmin ◽  
E. Cremonese ◽  
U. Morra di Cella ◽  
G. Filippa ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Snow Cover ◽  
Layer Thickness ◽  
Active Layer ◽  
Ground Surface ◽  
Small Scale ◽  
Active Layer Thickness ◽  
Spatial And Temporal Variability ◽  
Monitoring Site ◽  
European Alps

Abstract. The objective of this paper is to provide a first synthesis on the state and recent evolution of permafrost at the monitoring site of Cime Bianche (3100 m a.s.l.) on the Italian side of the Western Alps. The analysis is based on 7 years of ground temperature observations in two boreholes and seven surface points. The analysis aims to quantify the spatial and temporal variability of ground surface temperature in relation to snow cover, the small-scale spatial variability of the active layer thickness and current temperature trends in deep permafrost. Results show that the heterogeneity of snow cover thickness, both in space and time, is the main factor controlling ground surface temperatures and leads to a mean range of spatial variability (2.5 ± 0.1 °C) which far exceeds the mean range of observed inter-annual variability (1.6 ± 0.1 °C). The active layer thickness measured in two boreholes at a distance of 30 m shows a mean difference of 2.0 ± 0.1 m with the active layer of one borehole consistently deeper. As revealed by temperature analysis and geophysical soundings, such a difference is mainly driven by the ice/water content in the sub-surface and not by the snow cover regimes. The analysis of deep temperature time series reveals that permafrost is warming. The detected trends are statistically significant starting from a depth below 8 m with warming rates between 0.1 and 0.01 °C yr−1.

scholarly journals Linking tundra vegetation, snow, soil temperature, and permafrost

2020 ◽  
Author(s):  
Inge Grünberg ◽  
Evan J. Wilcox ◽  
Simon Zwieback ◽  
Philip Marsh ◽  
Julia Boike
Keyword(s):  
Snow Cover ◽  
Layer Thickness ◽  
Active Layer ◽  
Large Degree ◽  
Small Scale ◽  
Active Layer Thickness ◽  
Snow Melt ◽  
Vegetation Types ◽  
Soil Temperatures ◽  
Temporal And Spatial Characteristics

Abstract. Soil temperatures in permafrost regions are highly heterogeneous on small scales, in part due to variable snow and vegetation cover. Moreover, the temperature distribution that results from the interplay of complex biophysical processes remains poorly constrained. Sixty-eight temperature loggers were installed to record the distribution of topsoil temperatures at the Trail Valley Creek study site in the Northwestern Canadian Arctic. The measurements were distributed across six different vegetation types characteristic for this landscape. Two years of topsoil temperature data were analysed statistically to identify temporal and spatial characteristics and their relationship to vegetation, snow cover and active layer thickness. The mean annual topsoil temperature varied between −3.7 °C and 0.1 °C within a 1.2 km distance, with an approximate average across the landscape of −2.3 °C in 2017 and −1.7 °C in 2018. The observed variation can, to a large degree, be explained by variation in snow cover. Differences in height between vegetation types cause spatially variable snow depth during winter, leading to spatially variable snow melt timing in spring, causing pronounced differences in topsoil mean temperature and temperature variability during those time periods. Summer topsoil temperatures were quite similar below most vegetation types, and not consistently related to active layer thickness at the end of August. The small-scale pattern of vegetation and its influence on snow cover height and snow melt governs the annual topsoil temperature in this permafrost-underlain landscape.

Spatial variability of permafrost active-layer thickness under contemporary and projected climate in Northern Alaska

2012 ◽  
Vol 35 (2) ◽  
pp. 95-116 ◽  
Author(s):  
Dmitry A. Streletskiy ◽  
Nikolay I. Shiklomanov ◽  
Frederick E. Nelson
Keyword(s):  
Spatial Variability ◽  
Layer Thickness ◽  
Active Layer ◽  
Active Layer Thickness ◽  
Northern Alaska

scholarly journals Permafrost thaw and ground settlement considering long-term climate impact in northern Alaska

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhaohui Joey Yang ◽  
Kannon C. Lee ◽  
Haibo Liu
Keyword(s):  
Layer Thickness ◽  
Active Layer ◽  
Air Temperature ◽  
Climate Model ◽  
Ground Surface ◽  
Active Layer Thickness ◽  
Near Surface ◽  
Surface Conditions ◽  
Ice Content ◽  
Northern Alaska

AbstractAlaska’s North Slope is predicted to experience twice the warming expected globally. When summers are longer and winters are shortened, ground surface conditions in the Arctic are expected to change considerably. This is significant for Arctic Alaska, a region that supports surface infrastructure such as energy extraction and transport assets (pipelines), buildings, roadways, and bridges. Climatic change at the ground surface has been shown to impact soil layers beneath through the harmonic fluctuation of the active layer, and warmer air temperature can result in progressive permafrost thaw, leading to a deeper active layer. This study attempts to assess climate change based on the climate model data from the fifth phase of the Coupled Model Intercomparison Project and its impact on a permafrost environment in Northern Alaska. The predicted air temperature data are analyzed to evaluate how the freezing and thawing indices will change due to climate warming. A thermal model was developed that incorporated a ground surface condition defined by either undisturbed intact tundra or a gravel fill surface and applied climate model predicted air temperatures. Results indicate similar fluctuation in active layer thickness and values that fall within the range of minimum and maximum readings for the last quarter-century. It is found that the active layer thickness increases, with the amount depending on climate model predictions and ground surface conditions. These variations in active layer thickness are then analyzed by considering the near-surface frozen soil ice content. Analysis of results indicates that thaw strain is most significant in the near-surface layers, indicating that settlement would be concurrent with annual thaw penetration. Moreover, ice content is a major factor in the settlement prediction. This assessment methodology, after improvement, and the results can help enhance the resilience of the existing and future new infrastructure in a changing Arctic environment.

scholarly journals Active layer thermal monitoring at Fildes Peninsula, King George Island, Maritime Antarctica

2014 ◽  
Vol 6 (2) ◽  
pp. 1423-1449 ◽  
Author(s):  
R. F. M. Michel ◽  
C. E. G. R. Schaefer ◽  
F. N. B. Simas ◽  
Francelino M. R. ◽  
E. I. Fernandes-Filho ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Active Layer ◽  
Thermal Regime ◽  
Arima Model ◽  
Active Layer Thickness ◽  
Monitoring Site ◽  
King George Island ◽  
Data Logger ◽  
Maritime Antarctica ◽  
Fildes Peninsula

Abstract. International attention to the climate change phenomena has grown in the last decade; the active layer and permafrost are of great importance in understanding processes and future trends due to their role in energy flux regulation. The objective of the this paper is to present active layer temperature data for one CALM-S site located at Fildes Peninsula, King George Island, Maritime Antarctica over an fifth seven month period (2008–2012). The monitoring site was installed during the summer of 2008 and consists of thermistors (accuracy of ± 0.2 °C), arranged vertically with probes at different depths, recording data at hourly intervals in a~high capacity data logger. A series of statistical analysis were performed to describe the soil temperature time series, including a linear fit in order to identify global trend and a series of autoregressive integrated moving average (ARIMA) models were tested in order to define the best fit for the data. The controls of weather on the thermal regime of the active layer have been identified, providing insights about the influence of climate chance over the permafrost. The active layer thermal regime in the studied period was typical of periglacial environment, with extreme variation at the surface during summer resulting in frequent freeze and thaw cycles. The active layer thickness (ALT) over the studied period showed variability related to different annual weather conditions, reaching a maximum of 117.5 cm in 2009. The ARIMA model was considered appropriate to treat the dataset, enabling more conclusive analysis and predictions when longer data sets are available. Despite the variability when comparing temperature readings and active layer thickness over the studied period, no warming trend was detected.

scholarly journals Linking tundra vegetation, snow, soil temperature, and permafrost

2020 ◽  
Vol 17 (16) ◽  
pp. 4261-4279
Author(s):  
Inge Grünberg ◽  
Evan J. Wilcox ◽  
Simon Zwieback ◽  
Philip Marsh ◽  
Julia Boike
Keyword(s):  
Soil Temperature ◽  
Snow Cover ◽  
Layer Thickness ◽  
Active Layer ◽  
Vegetation Change ◽  
Vegetation Type ◽  
Spatial Scales ◽  
Active Layer Thickness ◽  
Vegetation Types ◽  
Thermal Dynamics

Abstract. Connections between vegetation and soil thermal dynamics are critical for estimating the vulnerability of permafrost to thaw with continued climate warming and vegetation changes. The interplay of complex biophysical processes results in a highly heterogeneous soil temperature distribution on small spatial scales. Moreover, the link between topsoil temperature and active layer thickness remains poorly constrained. Sixty-eight temperature loggers were installed at 1–3 cm depth to record the distribution of topsoil temperatures at the Trail Valley Creek study site in the northwestern Canadian Arctic. The measurements were distributed across six different vegetation types characteristic for this landscape. Two years of topsoil temperature data were analysed statistically to identify temporal and spatial characteristics and their relationship to vegetation, snow cover, and active layer thickness. The mean annual topsoil temperature varied between −3.7 and 0.1 ∘C within 0.5 km2. The observed variation can, to a large degree, be explained by variation in snow cover. Differences in snow depth are strongly related with vegetation type and show complex associations with late-summer thaw depth. While cold winter soil temperature is associated with deep active layers in the following summer for lichen and dwarf shrub tundra, we observed the opposite beneath tall shrubs and tussocks. In contrast to winter observations, summer topsoil temperature is similar below all vegetation types with an average summer topsoil temperature difference of less than 1 ∘C. Moreover, there is no significant relationship between summer soil temperature or cumulative positive degree days and active layer thickness. Altogether, our results demonstrate the high spatial variability of topsoil temperature and active layer thickness even within specific vegetation types. Given that vegetation type defines the direction of the relationship between topsoil temperature and active layer thickness in winter and summer, estimates of permafrost vulnerability based on remote sensing or model results will need to incorporate complex local feedback mechanisms of vegetation change and permafrost thaw.

scholarly journals Permafrost distribution and conditions at the headwalls of two receding glaciers (Schladming and Hallstatt glaciers) in the Dachstein Massif, Northern Calcareous Alps, Austria

2020 ◽  
Vol 14 (4) ◽  
pp. 1173-1186
Author(s):  
Matthias Rode ◽  
Oliver Sass ◽  
Andreas Kellerer-Pirklbauer ◽  
Harald Schnepfleitner ◽  
Christoph Gitschthaler
Keyword(s):  
Active Layer ◽  
Ground Surface ◽  
Ice Age ◽  
Small Scale ◽  
Active Layer Thickness ◽  
High Mountain ◽  
Glacier Surface ◽  
Near Surface ◽  
Rock Stability ◽  
Multi Method Approach

Abstract. Permafrost distribution in rock walls surrounding receding glaciers is an important factor in rock stability and rock wall retreat. We investigated bedrock permafrost distribution in the Dachstein Massif, Austria, reaching up to 2995 m a.s.l. The occurrence, thickness and thermal regime of permafrost at this partly glaciated mountain massif are scarcely known. We applied a multi-method approach with continuous ground surface and near-surface temperature monitoring (GST), measurement of the bottom temperature of the winter snow cover (BTS), electrical resistivity tomography (ERT), airborne photogrammetry, topographic maps, visual observations, and field mapping. Our research focused on several steep rock walls consisting of massive limestone above receding glaciers exposed to different slope aspects at elevations between ca. 2600 and 2700 m a.s.l. We aimed to quantify the distribution and conditions of bedrock permafrost particularly at the transition zone between the present glacier surface and the adjacent rock walls. According to our ground temperature data, permafrost is mainly found at north-facing rock walls. At south-east-facing rock walls, permafrost is probable only in very favourable cold conditions at radiation-sheltered higher elevations (>2700 m a.s.l.). ERT measurements reveal high resistivities (>30 000 Ω m) at ≥1.5 m depth at north-exposed slopes (highest values >100 kΩ m). Deducted from laboratory studies and additional small-scale ERT measurements, these values indicate permafrost existence. Permafrost bodies were found at several rock walls independent of investigated slope orientation; however, particularly large permafrost bodies were found at north-exposed sites. Furthermore, at vertical survey lines, a pronounced imprint of the former Little Ice Age (LIA) ice margin was detected. Resistivities above and below the LIA line are markedly different. At the LIA glacier surface, the highest resistivities and lowest active-layer thicknesses were observed. The active-layer thickness increases downslope from this zone. Permafrost below the LIA line could be due to permafrost aggradation or degradation; however, the spatial patterns of frozen rock point to permafrost aggradation following glacier surface lowering or retreat. This finding is significant for permafrost and cirque erosion studies in terms of frost-influence weathering in similar high-mountain settings.

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