Simulating high-latitude permafrost regions by the JSBACH terrestrial ecosystem model

Ekici, Altug; Beer, Christian; Hagemann, Stefan; Boike, Julia; Langer, Moritz; Hauck, Christian

doi:10.5194/gmd-7-631-2014

Cited by 139 publications

(207 citation statements)

References 89 publications

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“…Even though the vegetation cover along the geoelectrical profile is sparse, its influence in maintaining temperatures below freezing point can be seen using the electrical method and could be verified by eye inspection (at least in the zone where some stainless electrodes were forced into the ground). The spatial difference in the geographical distribution of the moss cover brings an additional heterogeneity to the soil thermal properties and dynamics in a small area (Ekici et al, 2014). This result confirms other observations in other regions with permafrost which show that vegetation cover and, in particular, mosses are natural insulators and maintain the ground temperature lower than if there were no mosses (Sharkhuu and Sharkhuu, 2012).…”

Section: Permafrost Distribution Based On Geophysical Methodssupporting

confidence: 81%

“…This increase in the density distribution of the mosses coincides with the increase of the electrical resistivity and thickness of the ground high electrical resistivities. The presence of a moss cover affects the soil heat transfer through thermal and hydrological insulation depending on the thickness and wetness of the moss (Ekici et al, 2014). Even though the vegetation cover along the geoelectrical profile is sparse, its influence in maintaining temperatures below freezing point can be seen using the electrical method and could be verified by eye inspection (at least in the zone where some stainless electrodes were forced into the ground).…”

Section: Permafrost Distribution Based On Geophysical Methodsmentioning

confidence: 94%

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Evaluation of frozen ground conditions along a coastal topographic gradient at Byers Peninsula (Livingston Island, Antarctica) by geophysical and geoecological methods

Correia

Oliva

Fernández

2017

CATENA

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Geophysical surveying and geoelectrical methods are effective to study permafrost distribution and conditions in polar environments. Geoelectrical methods are particularly suited to study the spatial distribution of permafrost because of its high electrical resistivity in comparison with that of soil or rock above 0°C. In the South Shetland Islands permafrost is considered to be discontinuous up to elevations of 20-40 m a.s.l., changing to continuous at higher altitudes. There are no specific data about the distribution of permafrost in Byers Peninsula, in Livingston Island, which is the largest ice-free area in the South Shetland Islands. With the purpose of better understanding the occurrence of permanent frozen conditions in this area, a geophysical survey using an electrical resistivity tomography (ERT) methodology was conducted during the January 2015 field season, combined with geomorphological and ecological studies. Three overlapping electrical resistivity tomographies of 78 m each were done along the same profile which ran from the coast to the highest raised beaches. The three electrical resistivity tomographies are combined in an electrical resistivity model which represents the distribution of the electrical resistivity of the ground to depths of about 13 m along 158 m. Several patches of high electrical resistivity were found, and interpreted as patches of sporadic permafrost. The lower limits of sporadic to discontinuous permafrost in the area are confirmed by the presence of permafrost-related landforms nearby. There is a close correspondence between moss patches and permafrost patches along the geoelectrical transect.

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Section: Permafrost Distribution Based On Geophysical Methodssupporting

confidence: 81%

Section: Permafrost Distribution Based On Geophysical Methodsmentioning

confidence: 94%

Evaluation of frozen ground conditions along a coastal topographic gradient at Byers Peninsula (Livingston Island, Antarctica) by geophysical and geoecological methods

Correia

Oliva

Fernández

2017

CATENA

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“…To allow liquid water to coexist with ice below 0 • C, a freezing point depression is included in the model and the maximum liquid water content for soil temperatures T s below T 0 = 273.15 K is formulated as (e.g. Cox et al, 1999;Niu and Yang, 2006;Ekici et al, 2014):…”

Section: Snow and Soil Temperaturementioning

confidence: 99%

PALADYN v1.0, a comprehensive land surface–vegetation–carbon cycle model of intermediate complexity

Willeit

Ganopolski

2016

Geosci. Model Dev.

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Abstract. PALADYN is presented; it is a new comprehensive and computationally efficient land surface-vegetationcarbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies.The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. PALADYN explicitly treats permafrost, both in physical processes and as an important carbon pool. It distinguishes nine surface types: five different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows the treatment of continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type, the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. The model includes a single snow layer.

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“…Recent developments in permafrost physics such as including soil freezing, organic soil properties, improved snow schemes, more realistic soil depths and physical impacts of mosses and lichens (Gouttevin et al, 2012;Lawrence et al, 2008;Ekici et al, 2014;Paquin and Sushama, 2015;Chadburn et al, 2015a, b;Porada et al, 2016) mean that the rate of permafrost thaw is now more realistic in many of the land surface components of ESMs. Adding a vertical representation of soil carbon is now required to enable a representation of permafrost carbon in ESMs (Tian et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A vertical representation of soil carbon in the JULES land surface scheme (vn4.3_permafrost) with a focus on permafrost regions

2017

Self Cite

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Abstract. An improved representation of the carbon cycle in permafrost regions will enable more realistic projections of the future climate-carbon system. Currently JULES (the Joint UK Land Environment Simulator) -the land surface model of the UK Earth System Model (UKESM) -uses the standard four-pool RothC soil carbon model. This paper describes a new version of JULES (vn4.3_permafrost) in which the soil vertical dimension is added to the soil carbon model, with a set of four pools in every soil layer. The respiration rate in each soil layer depends on the temperature and moisture conditions in that layer. Cryoturbation/bioturbation processes, which transfer soil carbon between layers, are represented by diffusive mixing. The litter inputs and the soil respiration are both parametrized to decrease with increasing depth. The model now includes a tracer so that selected soil carbon can be labelled and tracked through a simulation. Simulations show an improvement in the large-scale horizontal and vertical distribution of soil carbon over the standard version of JULES (vn4.3). Like the standard version of JULES, the vertically discretized model is still unable to simulate enough soil carbon in the tundra regions. This is in part because JULES underestimates the plant productivity over the tundra, but also because not all of the processes relevant for the accumulation of permafrost carbon, such as peat development, are included in the model. In comparison with the standard model, the vertically discretized model shows a delay in the onset of soil respiration in the spring, resulting in an increased net uptake of carbon during this time. In order to provide a more suitable representation of permafrost carbon for quantifying the permafrost carbon feedback within UKESM, the deep soil carbon in the permafrost region (below 1 m) was initialized using the observed soil carbon. There is now a slight drift in the soil carbon ( < 0.018 % decade −1 ), but the change in simulated soil carbon over the 20th century, when there is little climate change, is comparable to the original vertically discretized model and significantly larger than the drift.

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Simulating high-latitude permafrost regions by the JSBACH terrestrial ecosystem model

Cited by 139 publications

References 89 publications

Evaluation of frozen ground conditions along a coastal topographic gradient at Byers Peninsula (Livingston Island, Antarctica) by geophysical and geoecological methods

Evaluation of frozen ground conditions along a coastal topographic gradient at Byers Peninsula (Livingston Island, Antarctica) by geophysical and geoecological methods

PALADYN v1.0, a comprehensive land surface–vegetation–carbon cycle model of intermediate complexity

A vertical representation of soil carbon in the JULES land surface scheme (vn4.3_permafrost) with a focus on permafrost regions

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