Recent advances in permafrost modelling

Riseborough, D W; Shiklomanov, N. I.; Etzelmüller, Bernd; Gruber, Stephan; Marchenko, S. S.

doi:10.1002/ppp.615

Cited by 371 publications

(324 citation statements)

References 127 publications

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“…Note that thermal diffusivity values for sandstone are approximately the same as those used here, being κ ≈ 1.12 × 10 −6 m 2 /s. Heat transport into permafrost is typically modeled as a diffusive process (Riseborough et al, 2008). However, once melting occurs at the surface, advection of heat by liquid water (Rowland et al, 2011) could make our estimates of seasonal ground temperature fluctuations at depth conservative.…”

Section: Thermal Diffusion In Sandy Regolithmentioning

confidence: 99%

“…The solution (16) requires the approximation that the Stefan number, S ≡ L/(c p ∆T ), is large. Here we use the Stefan solution (16) to estimate the depth of thaw penetration, which is a standard procedure in permafrost modeling (Riseborough et al, 2008). We use a latent heat of fusion of L = γL 0 , where L 0 = 3 × 10 2 J/g is the value for pure ice and γ is the fraction of the ground that is ice rather than sand.…”

Section: Thermal Diffusion In Sandy Regolithmentioning

confidence: 99%

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New constraints on equatorial temperatures during a Late Neoproterozoic snowball Earth glaciation

Ewing

Eisenman

Lamb

et al. 2014

Earth and Planetary Science Letters

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Intense glaciation during the end of Cryogenian time (∼635 million years ago) marks the coldest climate state in Earth history -a time when glacial deposits accumulated at low, tropical paleolatitudes. The leading idea to explain these deposits, the snowball Earth hypothesis, predicts globally frozen surface conditions and subfreezing temperatures, with global climate models placing surface temperatures in the tropics between −20 • C and −60 • C. However, precise paleosurface temperatures based upon geologic constraints have remained elusive and the global severity of the glaciation undetermined. Here we make new geologic observations of tropical periglacial, aeolian and fluvial sedimentary structures formed during the end-Cryogenian, Marinoan glaciation in South Australia; these observations allow us to constrain ancient surface temperatures. We find periglacial sand wedges and associated deformation suggest that ground temperatures were sufficiently warm to allow for ductile deformation of a sandy regolith. The wide range of deformation structures likely indicate the presence of a paleoactive layer that penetrated 2-4 m below the ground surface. These observations, paired with a model of ground temperature forced by solar insolation, constrain the local mean annual surface temperature to within a few degrees of freezing. This temperature constraint matches well with our observations of fluvial deposits, which require temperatures sufficiently warm for surface runoff. Although this estimate coincides with one of the coldest near sea-level tropical temperatures in Earth history, if these structures represent peak Marinaon glacial conditions, they do not support the persistent deep freeze of the snowball Earth hypothesis. Rather, surface temperatures near 0 • C allow for regions of seasonal surface melting, atmosphere-ocean coupling and possible tropical refugia for early metazoans. If instead these structures formed during glacial onset or deglaciation, then they have implications for the timescale and character for the transition into or out of a snowball state.

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Section: Thermal Diffusion In Sandy Regolithmentioning

confidence: 99%

Section: Thermal Diffusion In Sandy Regolithmentioning

confidence: 99%

New constraints on equatorial temperatures during a Late Neoproterozoic snowball Earth glaciation

Ewing

Eisenman

Lamb

et al. 2014

Earth and Planetary Science Letters

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“…Numerical models have also proven useful to investigate energy and mass transfers among the atmosphere, snow cover and permafrost (Kane et al, 2001;Lunardini, 1998;Riseborough et al, 2008). In modelling studies, the importance of incorporating a seasonal snow cover as well as the effects of unfrozen water migration for time periods with freezing and thawing has been emphasised (Kane et al, 2001;Romanovsky and Osterkamp, 2000;Ling and Zhang, 2004).…”

Section: Introductionmentioning

confidence: 99%

Meltwater infiltration into the frozen active layer at an alpine permafrost site

Scherler

Hauck

Hoelzle

et al. 2010

Permafrost & Periglacial

109

115

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A coupled heat and mass transfer model simulating mass and energy balance of the soil-snow-atmosphere boundary layer was applied to simulate ground temperatures, together with water and ice content evolution, in the active layer of an alpine permafrost site on Schilthorn, Swiss Alps. Abrupt shifts and subsequent fluctuations in ground temperature observed in alpine permafrost boreholes at the beginning of the zero curtain phase in summer were explained by snowmelt and meltwater infiltration. Simulated water contents were compared to values derived from inverted electrical resistivity measurements and yielded a further independent validation of the model results. The study shows that infiltration into frozen soil takes place as an oscillating process in the model. This process is constrained by initial ground temperatures, infiltrability and the availability of meltwater from the snow cover.

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“…The proposed approach is based on the following assumptions: (i) the ground acts as a homogeneous mean (massive rock) with constant density and semi-infinite geometry (one-dimensional heat transfer problem), (ii) the temperatures at some depth below the borehole are stable and close to 0 • C, and (iii) heat transfer in the ground occurs only through the surface. This system is characterised and corresponds to the equilibrium model category as presented by Riseborough et al (2008). The ground Enthalpy balance ( H), in this case, is equivalent to the change in internal Energy of the ground between two thermodynamic states ( U).…”

Section: Enthalpy Change Modellingmentioning

confidence: 99%

Evaluation of the ground surface Enthalpy balance from bedrock temperatures (Livingston Island, Maritime Antarctic)

Ramos

Vieira

2009

The Cryosphere

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Abstract. The annual evolution of the ground temperatures from Incinerador borehole in Livingston Island (South Shetlands, Antarctic) is studied. The borehole is 2.4 m deep and is located in a massive quartzite outcrop with negligible water content, in the proximity of the Spanish Antarctic Station Juan Carlos I. In order to model the movement of the 0 • C isotherm (velocity and maximum depth) hourly temperature profiles from: (i) the cooling periods of the frost season of 2000 to 2005, and (ii) the warming periods of the thaw season of 2002-2003, 2003-2004 and 2004-2005, were studied. In this modelling approach, heat gains and losses across the ground surface are assumed to be the causes for the 0 • C isotherm movement. A methodological approach to calculate the ground Enthalpy change based on the thermodynamic analysis of the ground during the cooling and warming periods is proposed. The Enthalpy change into the rock is equivalent to the heat exchange through the ground surface during each season, thus enabling to describe the interaction groundatmosphere and providing valuable data for studies on permafrost and periglacial processes. The bedrock density and thermal conductivity are considered to be constant and initial isothermal conditions at 0 • C are assumed (based in collected data and local meteorological conditions in this area) to run the model in the beginning of each season. The final stages correspond to the temperatures at the end of the cooling and warming periods (annual minima and maxima). The application of this method avoids error propagation induced by the heat exchange calculations from multiple sensors using the Fourier method.

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Recent advances in permafrost modelling

Cited by 371 publications

References 127 publications

New constraints on equatorial temperatures during a Late Neoproterozoic snowball Earth glaciation

New constraints on equatorial temperatures during a Late Neoproterozoic snowball Earth glaciation

Meltwater infiltration into the frozen active layer at an alpine permafrost site

Evaluation of the ground surface Enthalpy balance from bedrock temperatures (Livingston Island, Maritime Antarctic)

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