The mathematical representation of freezing and thawing processes in variably-saturated, non-deformable soils

Kurylyk, Barret L.; Watanabe, Kunio

doi:10.1016/j.advwatres.2013.07.016

Cited by 293 publications

(270 citation statements)

References 126 publications

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“…Kurylyk and Watanabe (2013) compare several mathematical formulations for Table 1. Parameters used to calculate liquid water fraction.…”

Section: Methodsmentioning

confidence: 99%

“…Parameters used to calculate liquid water fraction. (2000) and Kurylyk and Watanabe (2013). We calculated the ϕ crit by inserting 0 • C into Eq.…”

Section: Methodsmentioning

confidence: 99%

“…Here we define substrate availability as the portion of soil organic matter accessible as a medium for microbial activity. The sharp decline in respiration results from the fact that soils maintain some liquid water at temperatures below freezing (Romanovsky and Osterkamp, 2000;Davis, 2001;Kurylyk and Watanabe, 2013). The mechanism is well understood: freezing point depression driven by the curvature of water around small, hydrophilic soil particles, analogous to freezing point depression caused by solutes in water (Davis, 2001).…”

Section: Introductionmentioning

confidence: 99%

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A parameterization of respiration in frozen soils based on substrate availability

Schaefer

Jafarov

2016

Biogeosciences

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Abstract. Respiration in frozen soils is limited to thawed substrate within the thin water films surrounding soil particles. As temperatures decrease and the films become thinner, the available substrate also decreases, with respiration effectively ceasing at −8 • C. Traditional exponential scaling factors to model this effect do not account for substrate availability and do not work at the century to millennial timescales required to model the fate of the nearly 1100 Gt of carbon in permafrost regions. The exponential scaling factor produces a false, continuous loss of simulated permafrost carbon in the 20th century and biases in estimates of potential emissions as permafrost thaws in the future. Here we describe a new frozen biogeochemistry parameterization that separates the simulated carbon into frozen and thawed pools to represent the effects of substrate availability. We parameterized the liquid water fraction as a function of temperature based on observations and use this to transfer carbon between frozen pools and thawed carbon in the thin water films. The simulated volumetric water content (VWC) as a function of temperature is consistent with observed values and the simulated respiration fluxes as a function of temperature are consistent with results from incubation experiments. The amount of organic matter was the single largest influence on simulated VWC and respiration fluxes. Future versions of the parameterization should account for additional, non-linear effects of substrate diffusion in thin water films on simulated respiration. Controlling respiration in frozen soils based on substrate availability allows us to maintain a realistic permafrost carbon pool by eliminating the continuous loss caused by the original exponential scaling factors. The frozen biogeochemistry parameterization is a useful way to represent the effects of substrate availability on soil respiration in model applications that focus on century to millennial timescales in permafrost regions.

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“…Kurylyk and Watanabe (2013) compare several mathematical formulations for Table 1. Parameters used to calculate liquid water fraction.…”

Section: Methodsmentioning

confidence: 99%

“…Parameters used to calculate liquid water fraction. (2000) and Kurylyk and Watanabe (2013). We calculated the ϕ crit by inserting 0 • C into Eq.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A parameterization of respiration in frozen soils based on substrate availability

Schaefer

Jafarov

2016

Biogeosciences

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“…These changes are caused by the difference in the hydraulic properties of frozen and unfrozen ground [21,22]. Several recent studies have related observed increases in winter baseflow to permafrost thaw.…”

Section: Introductionmentioning

confidence: 99%

Increasing Winter Baseflow in Response to Permafrost Thaw and Precipitation Regime Shifts in Northeastern China

Duan

Man

Kurylyk

et al. 2017

Water

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Abstract:Rapid permafrost thaw and precipitation regime shifts are altering surface and subsurface hydrological processes in arctic and subarctic watersheds. Long-term data (40 years) from two large permafrost watersheds in northeastern China, the Tahe River and Duobukuer River watersheds, indicate that winter baseflows are characterized by significant positive trends of 1.7% and 2.5%·year −1 , respectively. Winter baseflows exhibited statistically significant positive correlations with mean annual air temperature and the thawing index, an indicator of permafrost degradation, for both watersheds, as well as the increasing annual rainfall fraction of precipitation for the Duobukuer River watershed. Winter baseflows were characterized by a breakpoint in 1989, which lagged behind the mean annual air temperature breakpoint by only two years. The statistical analyses suggest that the increases in winter baseflow are likely related to enhanced groundwater storage and winter groundwater discharge caused by permafrost thaw and are potentially also due to an increase in the wet season rainfall. These hydrological trends are first apparent in marginal areas of permafrost distribution and are expected to shift northward towards formerly continuous permafrost regions in the context of future climate warming.

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“…However, such regional-and global-scale projections are difficult to constrain by measurements of soil properties made at vastly smaller scales of observation. This scale gap between the governing fine-scale physical processes and large-scale simulations impedes direct model validation against measurements, which has motivated development of fine-to intermediate-scale hydrothermal models (e.g., Hinzman et al, 1998;Hansson et al, 2004;Daanen et al, 2007;Mckenzie et al, 2007;Painter, 2011;Karra et al, 2014;Endrizzi et al, 2014;Yi et al, 2014); for a review see Kurylyk and Watanabe (2013). Numerical experiments using high-resolution coupled hydrothermal models, which are calibrated against fine-scale measurements, can play a fundamental role in understanding the governing physical processes of ALT formation.…”

Section: A L Atchley Et Al: Inform Thermal Hydrology Models Of Permentioning

confidence: 99%

Using field observations to inform thermal hydrology models of permafrost dynamics with ATS (v0.83)

et al. 2015

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Abstract. Climate change is profoundly transforming the carbon-rich Arctic tundra landscape, potentially moving it from a carbon sink to a carbon source by increasing the thickness of soil that thaws on a seasonal basis. However, the modeling capability and precise parameterizations of the physical characteristics needed to estimate projected active layer thickness (ALT) are limited in Earth system models (ESMs). In particular, discrepancies in spatial scale between field measurements and Earth system models challenge validation and parameterization of hydrothermal models. A recently developed surface-subsurface model for permafrost thermal hydrology, the Advanced Terrestrial Simulator (ATS), is used in combination with field measurements to achieve the goals of constructing a process-rich model based on plausible parameters and to identify fine-scale controls of ALT in ice-wedge polygon tundra in Barrow, Alaska. An iterative model refinement procedure that cycles between borehole temperature and snow cover measurements and simulations functions to evaluate and parameterize different model processes necessary to simulate freeze-thaw processes and ALT formation. After model refinement and calibration, reasonable matches between simulated and measured soil temperatures are obtained, with the largest errors occurring during early summer above ice wedges (e.g., troughs). The results suggest that properly constructed and calibrated onedimensional thermal hydrology models have the potential to provide reasonable representation of the subsurface thermal response and can be used to infer model input parameters and process representations. The models for soil thermal conductivity and snow distribution were found to be the most sensitive process representations. However, information on lateral flow and snowpack evolution might be needed to constrain model representations of surface hydrology and snow depth.

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The mathematical representation of freezing and thawing processes in variably-saturated, non-deformable soils

Cited by 293 publications

References 126 publications

A parameterization of respiration in frozen soils based on substrate availability

A parameterization of respiration in frozen soils based on substrate availability

Increasing Winter Baseflow in Response to Permafrost Thaw and Precipitation Regime Shifts in Northeastern China

Using field observations to inform thermal hydrology models of permafrost dynamics with ATS (v0.83)

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