New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: a comparison between permafrost and non-permafrost areas

Abstract. The thermal state of permafrost affects Earth surface systems and human activity in the Arctic and has implications for global climate. Improved understanding of the local-scale variability in the global ground thermal regime is required to account for its sensitivity to changing climatic and geoecological conditions. Here, we statistically related observations of mean annual ground temperature (MAGT) and active-layer thickness (ALT) to high-resolution (∼1 km2) geospatial data of climatic and local environmental conditions across the Northern Hemisphere. The aim was to characterize the relative importance of key environmental factors and the magnitude and shape of their effects on MAGT and ALT. The multivariate models fitted well to both response variables with average R2 values being ∼0.94 and 0.78. Corresponding predictive performances in terms of root-mean-square error were ∼1.31 ∘C and 87 cm. Freezing (FDD) and thawing (TDD) degree days were key factors for MAGT inside and outside the permafrost domain with average effect sizes of 6.7 and 13.6 ∘C, respectively. Soil properties had marginal effects on MAGT (effect size =0.4–0.7 ∘C). For ALT, rainfall (effect size =181 cm) and solar radiation (161 cm) were most influential. Analysis of variable importance further underlined the dominance of climate for MAGT and highlighted the role of solar radiation for ALT. Most response shapes for MAGT ≤0 ∘C and ALT were non-linear and indicated thresholds for covariation. Most importantly, permafrost temperatures had a more complex relationship with air temperatures than non-frozen ground. Moreover, the observed warming effect of rainfall on MAGT≤0∘C reverted after reaching an optimum at ∼250 mm, and that of snowfall started to level off at ∼300–400 mm. It is suggested that the factors of large global variation (i.e. climate) suppressed the effects of local-scale factors (i.e. soil properties and vegetation) owing to the extensive study area and limited representation of soil organic matter. Our new insights into the factors affecting the ground thermal regime at a 1 km scale should improve future hemispheric-scale studies.

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Theoretical approach describing the thermal regime of snow-covered sea ice

Annals of Glaciology ◽

10.3189/s0260305500011290 ◽

1993 ◽

Vol 18 ◽

pp. 79-84

Author(s):

Nobuo Ono ◽

Maxim S. Krass

Keyword(s):

Solar Radiation ◽

Sea Ice ◽

Snow Cover ◽

Air Temperature ◽

Thermal Regime ◽

Thermal State ◽

Equilibrium Phase ◽

Temperature Oscillations ◽

Oceanic Heat Flux ◽

Boundary Model

As the greater part of sea-ice area is covered with snow, the thermal regime of sea ice is characterized by the thermal behavior of snow-covered sea ice. In this paper the thermal regime of snow-covered sea ice is quantitatively investigated with a one-dimensional non-linear boundary model which contains: compaction of snow cover; internal absorption of solar radiation; evaporation–condensation within snow cover; equilibrium phase change of brine within sea ice; and vertical oceanic heat flux from seawater to ice. Penetration of air temperature oscillations into the snow-covered sea ice increases remarkably with increasing snow density. As internal melting within the snow-covered sea ice appears with increasing solar radiation, the rise in air temperature and increase of solar radiation in the springtime produce a corresponding change in the thermal state of sea ice, causing a drastic retreat of sea-ice cover. A case study for warm sea ice is presented describing the thermal state during the melting season.

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New insights into the environmental drivers of the circumpolar ground thermal regime

10.5194/tc-2018-144 ◽

2018 ◽

Author(s):

Olli Karjalainen ◽

Miska Luoto ◽

Juha Aalto ◽

Jan Hjort

Keyword(s):

Thermal Regime ◽

Climatic Factors ◽

Global Climate ◽

Thermal Conditions ◽

Cold Climate ◽

The Arctic ◽

Environmental Drivers ◽

Active Layer Thickness ◽

Thermal Dynamics ◽

Air Temperatures

Abstract. The thermal dynamics of permafrost shape Earth surface systems and human activity in the Arctic and have implications to global climate. Improved understanding of the fine-scale variability in the circumpolar ground thermal regime is required to account for its sensitivity to changing climatic and geoecological conditions. Here, we statistically related circumpolar observations of mean annual ground temperature (MAGT) and active-layer thickness (ALT) to high-resolution (~1 km2) geospatial data to identify their key environmental drivers. The multivariate models fitted well to MAGT and ALT observations with average R2 values being ~0.94 and 0.78, respectively. Corresponding predictive performances in terms of root mean square error were ~1.31 °C and 87 cm. Freezing air temperatures were the main driver of MAGT in permafrost conditions while thawing temperatures dominated when permafrost was not present. ALT was most strongly related to solar radiation and precipitation with an important influence from soil properties. Our findings suggest that in addition to climatic factors, initial ground thermal conditions and local-scale topography-soil-driven variability need to be considered in order to realistically assess the impacts of climate change on cold-climate geoecosystems.

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Thermal state of the active layer and permafrost along the Qinghai-Xizang (Tibet) railway from 2006 to 2010

The Cryosphere Discussions ◽

10.5194/tcd-5-2465-2011 ◽

2011 ◽

Vol 5 (5) ◽

pp. 2465-2481 ◽

Cited By ~ 3

Author(s):

Q. Wu ◽

T. Zhang ◽

Y. Liu

Keyword(s):

Linear Regression ◽

Layer Thickness ◽

Active Layer ◽

Thermal State ◽

Monitoring Network ◽

The Arctic ◽

Active Layer Thickness ◽

Different Depths ◽

The Mean ◽

Using Data

Abstract. In this study, we investigated changes in active layer thickness (ALT) and permafrost temperatures at different depths using data from permafrost monitoring network along the Qinghai-Xizang (Tibet) Railway since 2005. Among sites, average ALT is about 3.1 m with a range from about 1.1 m to 4.9 m. From 2006 through 2010, ALT has increased at a rate of about 6.3 cm a−1. The mean rising rate of permafrost temperature at the depth of 6.0 m is about 0.02 °C a−1 estimated by linear regression using five years of data, and the mean rising rate of mean annual ground temperature (MAGT) at depth of zero amplitude is about 0.012 °C a−1. Changes for colder permafrost (MAGT < −1.0 °C) is greater than that for relatively warmer permafrost (MAGT > −1.0 °C). This is consistent with results observed in the Arctic and Subarctic.

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New high-resolution estimates of the permafrost thermal state and hydrothermal conditions over the Northern Hemisphere

10.5194/essd-2021-83 ◽

2021 ◽

Author(s):

Youhua Ran ◽

Xin Li ◽

Guodong Cheng ◽

Jingxin Che ◽

Juha Aalto ◽

...

Keyword(s):

Northern Hemisphere ◽

Field Data ◽

Environmental Science ◽

Thermal State ◽

Physical Models ◽

Active Layer Thickness ◽

Areal Extent ◽

Hydrothermal Conditions ◽

Ensemble Strategy ◽

Permafrost Regions

Abstract. Monitoring of the thermal state of permafrost is important in environmental science and engineering applications. However, such data are generally unavailable mainly due to the lack of ground observations and the uncertainty of traditional physical models. This study produces novel permafrost datasets for the Northern Hemisphere (NH), including predictions of the mean annual ground temperature (MAGT) at the zero annual amplitude depth and active layer thickness (ALT) with a 1-km resolution for the period of 2000–2016, as well as estimates of the probability of permafrost occurrence and permafrost zonation based on hydrothermal conditions. These datasets integrate unprecedentedly large amounts of field data (1,002 boreholes for MAGT and 452 sites for ALT) and multisource geospatial data, especially remote sensing data, using statistical learning modelling with an ensemble strategy. Thus, these data are more accurate than those of previous circumpolar maps (bias = 0.02 ± 0.16 °C, RMSE = 1.32 ± 0.13 °C for MAGT; bias = 2.71 ± 16.46 cm, RMSE = 86.93 ± 19.61 cm for ALT). The datasets suggest that the areal extent of permafrost (MAGT ≤ 0 °C) in the NH, excluding glaciers and lakes, is approximately 15.03 (13.84–19.29) × 106 km2, and the areal extent of permafrost regions (permafrost probability > 0) is approximately 20.14 × 106 km2. The areal fractions of humid, semiarid/subhumid, and arid permafrost regions are 51.84 %, 44.83 %, and 3.33 %, respectively. The areal fractions of cold (≤ −3.0 °C), cool (−3.0 °C to −1.5 °C), and warm (> −1.5 °C) permafrost regions are 37.93 %, 14.35 %, and 47.72 %, respectively. These new datasets based on the most comprehensive field data to date contribute to an updated understanding of the thermal state and zonation of permafrost in the NH. They are potentially useful for various fields, such as in climatology, hydrology, ecology, agriculture, public health, and engineering planning. As a baseline, these datasets are also of great importance for evaluating future changes in MAGT, ALT, permafrost extent, and other spatial features of permafrost in the NH. All of the datasets are published through the National Tibetan Plateau Data Center (TPDC), and the link is https://data.tpdc.ac.cn/en/data/5093d9ff-a5fc-4f10-a53f-c01e7b781368 or https://doi.org/10.11888/Geocry.tpdc.271190 (Ran et al., 2021b).

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Thermal state of the active layer and permafrost along the Qinghai-Xizang (Tibet) Railway from 2006 to 2010

The Cryosphere ◽

10.5194/tc-6-607-2012 ◽

2012 ◽

Vol 6 (3) ◽

pp. 607-612 ◽

Cited By ~ 79

Author(s):

Q. Wu ◽

T. Zhang ◽

Y. Liu

Keyword(s):

Linear Regression ◽

Active Layer ◽

Temperature Rise ◽

Thermal State ◽

Monitoring Network ◽

The Arctic ◽

Active Layer Thickness ◽

Different Depths ◽

The Mean ◽

Using Data

Abstract. In this study, we investigated changes in active layer thickness (ALT) and permafrost temperatures at different depths using data from the permafrost monitoring network along the Qinghai-Xizang (Tibet) Railway (QXR) since 2005. Among these sites, mean ALT is ~3.1 m, with a range of ~1.1 to 5.9 m. From 2006 through 2010, ALT has increased at a rate of ~6.3 cm a−1. The mean rate of permafrost temperature rise at the depth of 6.0 m is ~0.02 °C a−1, estimated by linear regression using 5 yr of data, and the mean rate of mean annual ground temperature (MAGT) rise at a depth of zero amplitude is ~0.012 °C a−1. Changes for colder permafrost (MAGT −1.0 °C). This is consistent with results observed in the Arctic and subarctic.

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Evaluating the performance of coupled snow-soil models in SURFEXv8 to simulate the permafrost thermal regime at a high Arctic site

10.5194/gmd-2017-50 ◽

2017 ◽

Author(s):

Mathieu Barrere ◽

Florent Domine ◽

Bertrand Decharme ◽

Samuel Morin ◽

Vincent Vionnet ◽

...

Keyword(s):

Thermal Conductivity ◽

Soil Properties ◽

Thermal Regime ◽

Climate Changes ◽

High Arctic ◽

Global Climate Models ◽

Soil Freezing ◽

The Arctic ◽

Water Retention Capacity ◽

Coupled Models

Abstract. Global warming projections still suffer from a limited representation of the permafrost-carbon feedback. Predicting the response of the permafrost temperature to climate changes requires accurate simulations of the Arctic snow and soil properties. This study assesses the capacity of the coupled models ISBA-Crocus and ISBA-ES to simulate snow and soil properties at Bylot Island, a high Arctic site. Field measurements complemented with ERA-interim reanalysis were used to drive the models and to evaluate simulation outputs. Snow height, density, temperature, thermal conductivity and thermal resistance are examined to determine the critical variables involved in the soil thermal regime. Simulated soil properties are compared with measurements of thermal conductivity, temperature and water content. The simulated snow density profiles are erroneous, because Crocus and ES do not represent the upward water vapour fluxes generated by the strong temperature gradients within the snowpack. The resulting vertical profiles of thermal conductivity are inverted compared to observations, with high simulated values at the bottom of the snowpack. Still, ISBA-Crocus manages to successfully simulate the soil temperature in winter. Results are satisfactory in summer, but the temperature of the top soil could be better reproduced by representing adequately surface organic layers, i.e. mosses and litter, and in particular their water retention capacity. Transition periods (soil freezing and thawing) are the least well reproduced because the high basal snow thermal conductivity induces too rapid heat transfers between the soil and the snow in simulations. Hence, global climate models should carefully consider Arctic snow thermal properties, and especially the thermal conductivity of the basal snow layer, to perform accurate predictions of the permafrost evolution under climate changes.

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Theoretical approach describing the thermal regime of snow-covered sea ice

Annals of Glaciology ◽

10.1017/s0260305500011290 ◽

1993 ◽

Vol 18 ◽

pp. 79-84

Author(s):

Nobuo Ono ◽

Maxim S. Krass

Keyword(s):

Solar Radiation ◽

Sea Ice ◽

Snow Cover ◽

Air Temperature ◽

Thermal Regime ◽

Thermal State ◽

Equilibrium Phase ◽

Temperature Oscillations ◽

Oceanic Heat Flux ◽

Boundary Model

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Modelling of the thermal regime of permafrost during 1990–2014 in Hornsund, Svalbard

Polish Polar Research ◽

10.1515/popore-2016-0013 ◽

2016 ◽

Vol 37 (2) ◽

pp. 219-242 ◽

Cited By ~ 11

Author(s):

Tomasz Wawrzyniak ◽

Marzena Osuch ◽

Jarosław Napiórkowski ◽

Sebastian Westermann

Keyword(s):

Thermal Regime ◽

Environmental Changes ◽

Thermal State ◽

Ground Surface ◽

Temperature Data ◽

Ground Temperature ◽

The Arctic ◽

Transfer Model ◽

Numerical Heat Transfer ◽

Air Temperatures

AbstractThe thermal state of permafrost is a crucial indicator of environmental changes occurring in the Arctic. The monitoring of ground temperatures in Svalbard has been carried out in instrumented boreholes, although only few are deeper than 10 m and none are located in southern part of Spitsbergen. Only one of them, Janssonhaugen, located in central part of the island, provides the ground temperature data down to 100 m. Recent studies have proved that significant warming of the ground surface temperatures, observed especially in the last three decades, can be detected not only just few meters below the surface, but reaches much deeper layers. The aim of this paper is evaluation of the permafrost state in the vicinity of the Polish Polar Station in Hornsund using the numerical heat transfer model CryoGrid 2. The model is calibrated with ground temperature data collected from a 2 m deep borehole established in 2013 and then validated with data from the period 1990–2014 from five depths up to 1 m, measured routinely at the Hornsund meteorological station. The study estimates modelled ground thermal profile down to 100 m in depth and presents the evolution of the ground thermal regime in the last 25 years. The simulated subsurface temperature trumpet shows that multiannual variability in that period can reach 25 m in depth. The changes of the ground thermal regime correspond to an increasing trend of air temperatures observed in Hornsund and general warming across Svalbard.

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MONITORING OF THE THERMOABRASIONAL AND ACCUMULATIVE COASTS NEAR THE UNDERWATER GAS PIPELINE ROUTE ACROSS THE BAYDARATSKAYA BAY, KARA SEA

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b94878a9e64.97890040 ◽

2017 ◽

Author(s):

Nataliya Belova ◽

Alisa Baranskaya ◽

Osip Kokin ◽

...

Keyword(s):

Thermal Regime ◽

Storm Surges ◽

Gas Pipeline ◽

The Arctic ◽

Yamal Peninsula ◽

Permafrost Degradation ◽

Nearshore Zone ◽

Barrier Beach ◽

Energy Dissipater ◽

Pipeline Route

The coasts of Baydaratskaya Bay are composed by loose frozen sediments. At Yamal Peninsula accumulative coasts are predominant at the site where pipeline crosses the coast, while thermoabrasional coast are prevail at the Ural coast crossing site. Coastal dynamics monitoring on both sites is conducted using field and remote methods starting from the end of 1980s. As a result of construction in the coastal zone the relief morphology was disturbed, both lithodynamics and thermal regime of the permafrost within the areas of several km around the sites where gas pipeline crosses coastline was changed. At Yamal coast massive removal of deposits from the beach and tideflat took place. The morphology of barrier beach, which previously was a natural wave energy dissipater, was disturbed. This promoted inland penetration of storm surges and permafrost degradation under the barrier beach. At Ural coast the topsoil was disrupted by construction trucks, which affected thermal regime of the upper part of permafrost and lead to active layer deepening. Thermoerosion and thermoabrasion processes have activated on coasts, especially at areas with icy sediments, ice wedges and massive ice beds. Construction of cofferdams resulted in overlapping of sediments transit on both coasts and caused sediment deficit on nearby nearshore zone areas. The result of technogenic disturbances was widespread coastal erosion activation, which catastrophic scale is facilitated by climate warming in the Arctic.

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Enhanced Viral Activity in the Surface Microlayer of the Arctic and Antarctic Oceans

Microorganisms ◽

10.3390/microorganisms9020317 ◽

2021 ◽

Vol 9 (2) ◽

pp. 317

Author(s):

Dolors Vaqué ◽

Julia A. Boras ◽

Jesús Maria Arrieta ◽

Susana Agustí ◽

Carlos M. Duarte ◽

...

Keyword(s):

Environmental Factors ◽

Food Web ◽

Physicochemical Characteristics ◽

The Arctic ◽

Microbial Food Web ◽

Surface Microlayer ◽

Polar Regions ◽

Nutrient Inputs ◽

Viral Activity ◽

The Impact

The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column.

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