Improved modeling of permafrost dynamics in a GCM land‐surface scheme

Nicolsky, Dmitry; Romanovsky, V. E.; Alexeev, V. A.; Lawrence, David M.

doi:10.1029/2007gl029525

Cited by 206 publications

(208 citation statements)

References 16 publications

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“…Studies by Smerdon and Stieglitz (2006) and Alexeev et al (2007) documented limitations of climate models in simulating near-surface permafrost. They report that realistic simulation of soil temperatures in cold permafrost regions using LSMs with a zero-flux bottom boundary condition requires a total soil column depth of at least 30 m. Furthermore, Nicolsky et al (2007), and Dankers et al (2011) demonstrated the need to include soil organic carbon in LSMs for realistic simulations of soil thermal and moisture regimes and therefore ALT and permafrost extent, which in turn is important for realistic surface energy and water partitioning at the surface Rinke et al 2008). Indeed, organic material acts as an insulator, with its low thermal conductivity and relatively high heat content.…”

Section: Introductionmentioning

confidence: 99%

On the Arctic near-surface permafrost and climate sensitivities to soil and snow model formulations in climate models

Paquin

Sushama

2014

Clim Dyn

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Section: Introductionmentioning

confidence: 99%

On the Arctic near-surface permafrost and climate sensitivities to soil and snow model formulations in climate models

Paquin

Sushama

2014

Clim Dyn

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“…Such deeper soils have particular characteristics distinguishing them from both shallow active-layer soils and underlying permafrost: they are most affected by interannual variability in thaw depth, potentially flipping the C source-sink status of entire ecosystems (Goulden et al, 1998;Harden et al, 2012); they are subject to distinctive freeze-thaw, cryoturbation, and microbial dynamics, which are likely to change their sensitivity to climate change and feedback potential (Schuur et al, 2008); and they are known to pose particular problems for accurate modeling of high-latitude carbon dynamics (Nicolsky et al, 2007). These soils are likely to be a highly important contributor to future climate feedbacks, with modeling studies suggesting that one-third of 21st century climate-induced carbon loss may originate from seasonally frozen soil carbon .…”

Section: Introductionmentioning

confidence: 99%

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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Abstract. Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO 2 and CH 4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO 2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q 10 ) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH 4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH 4 fluxes. The cumulative production of C from CO 2 was over 6 orders of magnitude higher than that from CH 4 ; cumulative CO 2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52-73 % lower C. Cumulative CH 4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

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“…Recent measurements taken at wet tundra landscapes demonstrate the importance of the freeze and thaw dynamics for methane emission, which are related in a non-linear manner (Christensen et al, 2003;Sachs et al, 2008;Mastepanov et al, 2008). For this purpose, efforts have been initiated to incorporate permafrost and the annual freeze and thaw dynamics into global climate models (e.g., Stendel and Christensen, 2002;Lawrence and Slater, 2005;Nicolsky et al, 2007;Lawrence et al, 2008). In order to support and validate modeling, it is desirable to obtain regional process studies, which deliver important information about the landscape-specific energy balance characteristics and their determining factors.…”

Section: Introductionmentioning

confidence: 99%

The surface energy balance of a polygonal tundra site in northern Siberia – Part 1: Spring to fall

et al. 2011

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Abstract. In this article, we present a study on the surface energy balance of a polygonal tundra landscape in northeast Siberia. The study was performed during half-year periods from April to September in each of 2007 and 2008. The surface energy balance is obtained from independent measurements of the net radiation, the turbulent heat fluxes, and the ground heat flux at several sites. Short-wave radiation is the dominant factor controlling the magnitude of all the other components of the surface energy balance during the entire observation period. About 50% of the available net radiation is consumed by the latent heat flux, while the sensible and the ground heat flux are each around 20 to 30%. The ground heat flux is mainly consumed by active layer thawing. About 60% of the energy storage in the ground is attributed to the phase change of soil water. The remainder is used for soil warming down to a depth of 15 m. In particular, the controlling factors for the surface energy partitioning are snow cover, cloud cover, and the temperature gradient in the soil. The thin snow cover melts within a few days, during which the equivalent of about 20% of the snow-water evaporates or sublimates. Surface temperature differences of the heterogeneous landscape indicate spatial variabilities of sensible and latent heat fluxes, which are verified by measurements. However, spatial differences in the partitioning between sensible and latent heat flux are only measured during conditions of high radiative forcing, which only occur occasionally.

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Improved modeling of permafrost dynamics in a GCM land‐surface scheme

Cited by 206 publications

References 16 publications

On the Arctic near-surface permafrost and climate sensitivities to soil and snow model formulations in climate models

On the Arctic near-surface permafrost and climate sensitivities to soil and snow model formulations in climate models

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

The surface energy balance of a polygonal tundra site in northern Siberia – Part 1: Spring to fall

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