A model for regional-scale estimation of temporal and spatial variability of active layer thickness and mean annual ground temperatures

The purpose of this article was to compile four separate digital thematic maps of temperature and ice content of permafrost, the active layer thickness, and cryogenic processes in Yakutia as a basis for assessing changes to modern climate changes and anthropogenic disturbances. In this work, materials on permafrost were used, serving as the basis for compiling a permafrost landscape map of the Republic of Sakha (Yakutia). The maps were compiled using ArcGIS software, which supports attribute table mapping. The ground temperature and active layer thickness maps reflected landscape zonality and regional differences. Peculiarities of genetic types of Quaternary deposits and climatic conditions reflected the ice content of surface sediments and cryogenic process distribution maps. One of the most common is ground temperatures from −2.1 to −4.0 °C, which were found to occupy about 37.4% of the territory of Yakutia. More than half of the region was found to be occupied by permafrost landscapes with a limited thickness of the active layer up to 1.1 m. Ice-rich permafrost (more than 0.4 in ice content) was found to be typical for about 40% of the territory. Thermokarst is the most hazardous process that occurs in half of Yakutia.

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Climate warming and active layer thaw in the boreal and tundra environments of the Mackenzie Valley

Canadian Journal of Earth Sciences ◽

10.1139/e06-121 ◽

2007 ◽

Vol 44 (6) ◽

pp. 733-743 ◽

Cited By ~ 33

Author(s):

Ming-ko Woo ◽

Michael Mollinga ◽

Sharon L Smith

Keyword(s):

Layer Thickness ◽

Active Layer ◽

Climate Warming ◽

Probability Distributions ◽

Organic Layer ◽

Active Layer Thickness ◽

Near Surface ◽

Ground Temperatures ◽

Thaw Depth ◽

Mineral Soils

The variability of maximum active layer thickness in boreal and tundra environments has important implications for hydrological processes, terrestrial and aquatic ecosystems, and the integrity of northern infrastructure. For most planning and management purposes, the long-term probability distribution of active layer thickness is of primary interest. A robust method is presented to calculate maximum active layer thickness, employing the Stefan equation to compute phase change of moisture in soils and using air temperature as the sole climatic forcing variable. Near-surface ground temperatures (boundary condition for the Stefan equation) were estimated based on empirical relationships established for several sites in the Mackenzie valley. Simulations were performed for typically saturated mineral soils, overlain with varying thickness of peat in boreal and tundra environments. The probability distributions of simulated maximum active layer thickness encompass the range of measured thaw depths provided by field data. The effects of climate warming under A2 and B2 scenarios for 2050 and 2100 were investigated. Under the A2 scenario in 2100, the simulated median thaw depth under a thin organic cover may increase by 0.3 m, to reach 1 m depth for a tundra site and 1.6 m depth for a boreal site. The median thaw depth in 2100 is dampened by about 50% under a 1 m thick organic layer. Without an insulating organic cover, thaw penetration can increase to reach 1.7 m at the tundra site. The simulations provide quantitative support that future thaw penetration in permafrost terrain will deepen differentially depending on location and soil.

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Modelling borehole temperatures in Southern Norway – insights into permafrost dynamics during the 20th and 21st century

The Cryosphere ◽

10.5194/tc-6-553-2012 ◽

2012 ◽

Vol 6 (3) ◽

pp. 553-571 ◽

Cited By ~ 32

Author(s):

T. Hipp ◽

B. Etzelmüller ◽

H. Farbrot ◽

T. V. Schuler ◽

S. Westermann

Keyword(s):

Layer Thickness ◽

Active Layer ◽

21St Century ◽

Little Ice Age ◽

Ice Age ◽

Active Layer Thickness ◽

Ground Temperatures ◽

Air Temperatures ◽

Mountain Permafrost ◽

Southern Norway

Abstract. 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.

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Transient modeling of the ground thermal conditions using satellite data in the Lena River Delta, Siberia

10.5194/tc-2016-130 ◽

2016 ◽

Cited By ~ 1

Author(s):

Sebastian Westermann ◽

Maria Peter ◽

Moritz Langer ◽

Georg Schwamborn ◽

Lutz Schirrmeister ◽

...

Keyword(s):

Surface Temperature ◽

Layer Thickness ◽

Active Layer ◽

Thermal Conditions ◽

River Delta ◽

Active Layer Thickness ◽

Lena River ◽

Ground Temperatures ◽

Lena River Delta

Abstract. 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 approx. 16 000 km2 in the Lena River Delta 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 (MODIS Land Surface Temperature, MODIS Snow Extent, GlobSnow Snow Water Equivalent) 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 a satisfactory agreement both 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 in the Lena River Delta which suggests that thaw depths are in most cases reproduced to within 0.1 m or less and multi-year averages of ground temperatures within 1 to 1.5 °C. The warmest 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 coldest temperatures are modeled for the eastern part, 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 the satellite-based model scheme is generally capable of estimating the thermal state of permafrost 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.

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

The Cryosphere Discussions ◽

10.5194/tcd-8-4033-2014 ◽

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.

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Statistical Forecasting of Current and Future Circum-Arctic Ground Temperatures and Active Layer Thickness

Geophysical Research Letters ◽

10.1029/2018gl078007 ◽

2018 ◽

Vol 45 (10) ◽

pp. 4889-4898 ◽

Cited By ~ 23

Author(s):

J. Aalto ◽

O. Karjalainen ◽

J. Hjort ◽

M. Luoto

Keyword(s):

Layer Thickness ◽

Active Layer ◽

Active Layer Thickness ◽

Statistical Forecasting ◽

Ground Temperatures

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Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

The Cryosphere ◽

10.5194/tc-11-1441-2017 ◽

2017 ◽

Vol 11 (3) ◽

pp. 1441-1463 ◽

Cited By ~ 19

Author(s):

Sebastian Westermann ◽

Maria Peter ◽

Moritz Langer ◽

Georg Schwamborn ◽

Lutz Schirrmeister ◽

...

Keyword(s):

Remote Sensing ◽

Layer Thickness ◽

Active Layer ◽

Thermal Conditions ◽

River Delta ◽

Active Layer Thickness ◽

Lena River ◽

Ground Temperatures ◽

Lena River Delta

Abstract. 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.

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