A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data

Westermann, Sebastian; Østby, Torbjørn Ims; Gisnås, Kjersti; Schuler, Thomas; Etzelmüller, Bernd

doi:10.5194/tcd-9-753-2015

Cited by 22 publications

(35 citation statements)

References 47 publications

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“…Significant progress has been achieved over recent decades in modeling ground freezing and thawing and coupling these processes to hydrological and land surface models. A semiempirical permafrost model CryoGrid 1 based on the temperature at the top of permafrost (TTOP) approach was employed to map the North Atlantic permafrost region at a spatial resolution of 1 km at continental scales [ Westermann et al ., ]. The TTOP approach is one of the old modeling schemes which delivers a mean annual ground temperature (MAGT) and identifies permafrost by MAGT ≤ 0°C [ Gisnås et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Development of an enthalpy‐based frozen soil model and its validation in a cold region in China

et al. 2016

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An enthalpy-based frozen soil model was developed for the simulation of water and energy transfer in cold regions. To simulate the soil freezing/thawing processes stably and efficiently, a three-step algorithm was applied to solve the nonlinear governing equations: (1) a thermal diffusion equation was implemented to simulate the heat conduction between soil layers; (2) a freezing/thawing scheme used a critical temperature criterion to judge the phase status and introduced enthalpy and total water mass into freezing depression equation to represent ice formation/melt and corresponding latent heat release/absorption; and (3) a water flow scheme was employed to describe the liquid movement within frozen soil. In addition, a parameterization set of hydraulic and thermal properties was updated by considering the frozen soil effect. The performance of the frozen soil model was validated at point scale in a typical mountainous permafrost basin of China. An ice profile initialization method is proposed for permafrost modeling. Results show that the model can achieve a convergent solution at a time step of hourly and a surface layer thickness of centimeters that are typically used in current land surface models. The simulated profiles of soil temperature, liquid water content, ice content and thawing front depth are in good agreement with the observations and the characteristics of permafrost. The model is capable of continuously reproducing the diurnal and seasonal freeze-thaw cycle and simulating frozen soil hydrological processes.Significant progress has been achieved over recent decades in modeling ground freezing and thawing and coupling these processes to hydrological and land surface models. A semiempirical permafrost model BAO ET AL.AN ENTHALPY-BASED FROZEN SOIL MODEL 5259

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Section: Introductionmentioning

confidence: 99%

Development of an enthalpy‐based frozen soil model and its validation in a cold region in China

et al. 2016

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“…As a subsurface thermal condition of soil, however, permafrost is a challenge to detect remotely. Diverse approaches to indirectly map permafrost have been developed, including geophysical techniques using airborne electromagnetic (AEM) data [22], thermal modeling of ground temperatures using climate data and/or land surface temperatures [2,[23][24][25], and statistical-empirical methods relating land cover, topography, and spectral indices to permafrost characteristics [26][27][28]. This study applies the latter approach of establishing empirical relationships of remote sensing data with permafrost conditions, specifically within a wildfire burn.…”

Section: Introductionmentioning

confidence: 99%

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Brown

Jorgenson²,

Kielland

et al. 2016

Remote Sensing

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Climate change coupled with an intensifying wildfire regime is becoming an important driver of permafrost loss and ecosystem change in the northern boreal forest. There is a growing need to understand the effects of fire on the spatial distribution of permafrost and its associated ecological consequences. We focus on the effects of fire a decade after disturbance in a rocky upland landscape in the interior Alaskan boreal forest. Our main objectives were to (1) map near-surface permafrost distribution and drainage classes and (2) analyze the controls over landscape-scale patterns of post-fire permafrost degradation. Relationships among remote sensing variables and field-based data on soil properties (temperature, moisture, organic layer thickness) and vegetation (plant community composition) were analyzed using correlation, regression, and ordination analyses. The remote sensing data we considered included spectral indices from optical datasets (Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI)), the principal components of a time series of radar backscatter (Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar (ALOS-PALSAR)), and topographic variables from a Light Detection and Ranging (LiDAR)-derived digital elevation model (DEM). We found strong empirical relationships between the normalized difference infrared index (NDII) and post-fire vegetation, soil moisture, and soil temperature, enabling us to indirectly map permafrost status and drainage class using regression-based models. The thickness of the insulating surface organic layer after fire, a measure of burn severity, was an important control over the extent of permafrost degradation. According to our classifications, 90% of the area considered to have experienced high severity burn (using the difference normalized burn ratio (dNBR)) lacked permafrost after fire. Permafrost thaw, in turn, likely increased drainage and resulted in drier surface soils. Burn severity also influenced plant community composition, which was tightly linked to soil temperature and moisture. Overall, interactions between burn severity, topography, and vegetation appear to control the distribution of near-surface permafrost and associated drainage conditions after disturbance.

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“…High latitude permafrost peatlands currently face dramatic changes in temperature (Hecht et al, 2007;Westermann et al, 2015), and the predicted 37% reduction of the permafrost extent by 2100 (IPCC 2013) is likely to result in significant changes in soil drainage. Although whether permafrost peatlands will become wetter or drier is still uncertain (e.g., Swindles et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Iron and silicon isotope behaviour accompanying weathering in Icelandic soils, and the implications for iron export from peatlands

Opfergelt

Williams

Cornélis

et al. 2017

Geochimica et Cosmochimica Acta

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Incipient warming of peatlands at high latitudes is expected to modify soil drainage and hence the redox conditions, which has implications for Fe export from soils. This study uses Fe isotopes to assess the processes controlling Fe export in a range of Icelandic soils including peat soils derived from the same parent basalt, where Fe isotope variations principally reflect differences in weathering and drainage. In poorly weathered, well-drained soils (non-peat soils), the limited Fe isotope fractionation in soil solutions relative to the bulk soil (D 57 Fe solution-soil = À0.11 ± 0.12‰) is attributed to proton-promoted mineral dissolution. In the more weathered poorly drained soils (peat soils), the soil solutions are usually lighter than the bulk soil (D 57 Fe solution-soil = À0.41 ± 0.32‰), which indicates that Fe has been mobilised by reductive mineral dissolution and/or ligand-controlled dissolution. The results highlight the presence of Fe-organic complexes in solution in anoxic conditions. An additional constraint on soil weathering is provided by Si isotopes. The Si isotope composition of the soil solutions relative to the soil (D 30 Si solution-soil = 0.92 ± 0.26‰) generally reflects the incorporation of light Si isotopes in secondary aluminosilicates. Under anoxic conditions in peat soils, the largest Si isotope fractionation in soil solutions relative to the bulk soil is observed (D 30 Si solution-soil = 1.63 ± 0.40‰) and attributed to the cumulative contribution of secondary clay minerals and amorphous silica precipitation. Si supersaturation in solution with respect to amorphous silica is reached upon freezing when Al availability to form aluminosilicates is limited by the affinity of Al for metal-organic complexes. Therefore, the precipitation of amorphous silica in peat soils indirectly supports the formation of metal-organic complexes in poorly drained soils. These observations highlight that in a scenario of decreasing soil drainage with warming high latitude peatlands, Fe export from soils as Fe-organic complexes will increase, which in turn has implications for Fe transport in rivers, and ultimately the delivery of Fe to the oceans.

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A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data

Cited by 22 publications

References 47 publications

Development of an enthalpy‐based frozen soil model and its validation in a cold region in China

Development of an enthalpy‐based frozen soil model and its validation in a cold region in China

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Iron and silicon isotope behaviour accompanying weathering in Icelandic soils, and the implications for iron export from peatlands

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