Spatial Distribution Of Permafrost Research Articles

Impacts of Climate Change on Permafrost and Hydrological Processes in Northeast China

Permafrost is very sensitive to climate change, and the accelerated degradation of permafrost in Northeast China caused by global climate change will change the hydrological and ecological processes in the region and cause significant impacts on natural systems and human activities. In this study, the spatial distribution of permafrost in Northeast China from 2000 to 2020 was simulated using an improved ground freezing number model. The spatial and temporal variations of permafrost thickness and active layer thickness were estimated using the mean ground temperature method based on the obtained permafrost distribution. Based on the above simulation results, the mean annual ground temperature and field monitoring temperature gradient, based on remote sensing estimation and the ice content data of permafrost, were used to calculate the amount of permafrost ice storage in Northeast China for many years and to predict the amount of water released from permafrost in the future to better reveal the influence of permafrost changes on ecohydrological changes in the watershed. The results show that, in the past 20 years, climate warming has led to the degradation of the permafrost area in Northeast China from 3.31 × 105 km2 to 2.70 × 105 km2, with a degradation rate of 18.43%; the stored ice in the permafrost has been released at an accelerated rate. The total ice storage volume in the permafrost of Northeast China is 3.178 × 1011 m3. The amount of ice storage in the permafrost increases with latitude and altitude, and the ice storage volume decreases to 6.641 × 1010 m3 after 100 years, which is a decrease of 2.514 × 1011 m3. The amount of water released due to permafrost degradation accounts for 79.11% of the current total ice storage, and the rate of water release reaches 2.51 × 109 m3/a. The release of water from permafrost has an important impact on river runoff whose source is at high altitudes, such as the Greater and Lesser Khingan Mountains in Northeast China.

Field Investigation on Thermal Regime of Permafrost and Talik in a River Terrace, the Interior of Qinghai-Tibet Plateau

To carry out engineering construction in a permafrost area, it is of great importance to grasp the spatial distribution of permafrost and its hydrothermal characteristics within the scope of engineering activities. Compared with the continuous permafrost area, the permafrost distribution in discontinuous permafrost area is complicated due to existence of island talik, which causes highly poor continuity and uniformity of ground hydrothermal conditions and brings great difficulty and uncertainty to the engineering geological investigation. In the present study, the spatial distribution of permafrost and the freeze-thaw process of shallow ground at the I-stage terrace of a river on the Qinghai-Tibet Plateau were studied based on field investigation including drilling, electrical resistivity tomography, and borehole temperature measurement. The results show that the relict permafrost, patchy permafrost, and island talik are distributed in the limited range of the study area. Among them, the buried depth of relict permafrost layer is in the range of 7 ~ 14 m, while the patchy permafrost layer is in the range of 3.0 ~ 17.0 m depth, and the mean annual ground temperature of both is close to -0.1°C, which belongs to extremely high-temperature permafrost. The seasonal freezing/thawing depths of shallow ground within the relict permafrost, patchy permafrost, and island talik range from 2.5 to 3.0 m. The freezing period of the seasonal freezing layer is 5.5 months, while the thawing period of the seasonal thawing layer is 6 months. The complex plane and spatial distribution of permafrost in the field are closely related to local factors such as topography, geomorphology, groundwater, and lithology of shallow ground. It is believed that the formation of the island talik in the study area is controlled by solar radiation and precipitation infiltration.

Spatial Distribution of Permafrost in the Xing’an Mountains of Northeast China from 2001 to 2018

Permafrost is a key element of the cryosphere and sensitive to climate change. High-resolution permafrost map is important to environmental assessment, climate modeling, and engineering application. In this study, to estimate high-resolution Xing’an permafrost map (up to 1 km2), we employed the surface frost number (SFN) model and ground temperature at the top of permafrost (TTOP) model for the 2001–2018 period, driven by remote sensing data sets (land surface temperature and land cover). Based on the comparison of the modeling results, it was found that there was no significant difference between the two models. The performances of the SFN model and TTOP model were evaluated by using a published permafrost map. Based on statistical analysis, both the SFN model and TTOP model efficiently estimated the permafrost distribution in Northeast China. The extent of Xing’an permafrost distribution simulated by the SFN model and TTOP model were 6.88 × 105 km2 and 6.81 × 105 km2, respectively. Ground-surface characteristics were introduced into the permafrost models to improve the performance of models. The results provided a basic reference for permafrost distribution research at the regional scale.

The Development Trend and Research Frontiers of Distributed Hydrological Models—Visual Bibliometric Analysis Based on Citespace

Based on the bibliometric and data visualization analysis software Citespace, this study carried out document statistics and information mining on the Web of Science database and characterized the distributed hydrological model knowledge system from 1986 to 2019. The results show a few things: (1) from 1986 to 2019, the United States and China accounted for 41% of the total amount of publications, and they were the main force in the field of distributed hydrological model research; (2) field research involves multiple disciplines, mainly covering water resources, geology, earth sciences, environmental sciences, ecology and engineering; (3) the frontier of field research has shifted from using distributed hydrological models in order to simulate runoff and nonpoint source environmental responses to the coupling of technologies and products that can obtain high-precision, high-resolution data with distributed hydrological models. (4) Affected by climate warming, the melting of glaciers has accelerated, and the spatial distribution of permafrost and water resources have changed, which has caused a non-negligible impact on the hydrological process. Therefore, the development of distributed hydrological models suitable for alpine regions and the response of hydrological processes to climate change have also become important research directions at present.

A Long-Term, 1-km Resolution Daily Meteorological Dataset for Modeling and Mapping Permafrost in Canada

Climate warming is causing permafrost thaw and there is an urgent need to understand the spatial distribution of permafrost and its potential changes with climate. This study developed a long-term (1901–2100), 1-km resolution daily meteorological dataset (Met1km) for modeling and mapping permafrost at high spatial resolutions in Canada. Met1km includes eight climate variables (daily minimum, maximum, and mean air temperatures, precipitation, vapor pressure, wind speed, solar radiation, and downward longwave radiation) and is suitable to drive process-based permafrost and other land-surface models. Met1km was developed based on four coarser gridded meteorological datasets for the historical period. Future values were developed using the output of a new Canadian regional climate model under medium-low and high emission scenarios. These datasets were downscaled to 1-km resolution using the re-baselining method based on the WorldClim2 dataset as spatial templates. We assessed Met1km by comparing it to climate station observations across Canada and a gridded monthly anomaly time-series dataset. The accuracy of Met1km is similar to or better than the four coarser gridded datasets. The errors in long-term averages and average seasonal patterns are small. The error occurs mainly in day-to-day fluctuations, thus the error decreases significantly when averaged over 5 to 10 days. Met1km, as a data generating system, is relatively small in data volume, flexible to use, and easy to update when new or improved source datasets are available. The method can also be used to generate similar datasets for other regions, even for the entire global landmass.

Characteristic, changes and impacts of permafrost on Qinghai-Tibet Plateau

Qinghai-Tibet Plateau (QTP) is the largest high-altitude permafrost zone in the mid-latitudes. Due to the climate warming, permafrost degradation on the QTP has been widely recorded in the past decades. Since it greatly affects the East Asian monsoon, and even the global climate system, it is extremely important to understand permafrost current state, changes and its impacts. Based on literature reviews and some new data, this paper summarizes the characteristics of the current state permafrost on the QTP, including the active layer thickness (ALT), the spatial distribution of permafrost, permafrost temperature and thickness, as well as the ground ice and soil carbon storage in permafrost region. The new results showed that the permafrost and seasonally frozen ground area (excluding glaciers and lakes) is 1.06 million square kilometers and 1.45 million square kilometers on the QTP. The sub-stable, transitional, and unstable permafrost accounts for 30.4%, 22.1% and 22.6% of the total permafrost area. The permafrost thickness varies greatly among topography, with the maximum value in mountainous areas, which could be deeper than 200 m, while the minimum value in the flat areas and mountain valleys, which could be less than 60 m. The mean active layer thickness of the permafrost on the QTP is 2.3 m, with 80% of the permafrost regions ranges from 0.8 m to 3.5 m. During 1980 to 2015, soil temperature at 0−10, 10−40, 40−100, 100−200 cm increased at a rate of 0.439, 0.449, 0.396, and 0.259°C/ 10 a, respectively. From 2004 to 2018, the increasing rate of the soil temperature at the bottom of active layer was 0.486°C/ 10 a. These results show that the permafrost degradation has been accelerating. The permafrost degradation largely reduces the soil moisture. The ground ice volume of the permafrost is estimated up to 1.27×104 km3 (liquid water equivalent). The soil organic carbon in the upper 2 m of permafrost region is about 17 Pg; there is a large uncertainty in this estimation however due to the great heterogeneities in the soil column. Although the permafrost ecosystem is a carbon sink at the present, it is possible that it will shift to a carbon source due to the loss of soil organic carbon along with permafrost degradation. Overall, this paper shows that the plateau permafrost has undergone remarkable degradation during past decades, which are clearly proven by the increasing ALTs and ground temperature. Most of the permafrost on the QTP belongs to the unstable permafrost, meaning that permafrost over TPQ is very sensitive to climate warming. The permafrost interacts closely with water, soil, greenhouse gases emission and biosphere. Therefore, the permafrost degradation greatly affects the regional hydrology, ecology and even the global climate system. This paper also proposes approaches and methods to study the interactive mechanisms between permafrost and climate change, and the results can serve as a scientific basis for environmental protection, engineering design and construction in cold regions.

Spatially-explicit estimate of soil nitrogen stock and its implication for land model across Tibetan alpine permafrost region

Permafrost soils store a large amount of nitrogen (N) which could be activated under the continuous climate warming. However, compared with carbon (C) stock, little is known about the size and spatial distribution of permafrost N stock. By combining measurements from 519 pedons with two machine learning models (supporting vector machine (SVM) and random forest (RF)), we estimated the size and spatial distribution of N stock across the Tibetan alpine permafrost region. We then compared these spatially-explicit N estimates with simulated N stocks from the Community Land Model (CLM). We found that N density (N amount per area) in the top three meters was 1.58 kg N m−2 (interquartile range: 1.40–1.76) across the study area, constituting a total of 1802 Tg N (interquartile range: 1605–2008), decreasing from the southeast to the northwest of the plateau. N stored below 1 m accounted for 48% of the total N stock in the top three meters. CLM4.5 significantly underestimated the N stock on the Tibetan Plateau, primarily in areas with arid/semi-arid climate. The process of biological N fixation played a key role in the underestimation of N stock prediction. Overall, our study highlights that it is imperative to improve the simulation of N processes and permafrost N stocks in land models to better predict ecological consequences induced by rapid and widespread permafrost degradation.

Impact of dynamic vegetation phenology on the simulated pan-Arctic land surface state

The pan-Arctic land surface is undergoing rapid changes in a warming climate, with near-surface permafrost projected to degrade significantly during the twenty-first century. Vegetation-related feedbacks have the potential to influence the rate of degradation of permafrost. In this study, the impact of dynamic phenology on the pan-Arctic land surface state, particularly near-surface permafrost, for the 1961–2100 period, is assessed by comparing two simulations of the Canadian Land Surface Scheme (CLASS)—one with dynamic phenology, modelled using the Canadian Terrestrial Ecosystem Model (CTEM), and the other with prescribed phenology. These simulations are forced by atmospheric data from a transient climate change simulation of the 5th generation Canadian Regional Climate Model (CRCM5) for the Representative Concentration Pathway 8.5 (RCP8.5). Comparison of the CLASS coupled to CTEM simulation to available observational estimates of plant area index, spatial distribution of permafrost and active layer thickness suggests that the model captures reasonably well the overall distribution of vegetation and permafrost. It is shown that the most important impact of dynamic phenology on the land surface occurs through albedo and it is demonstrated for the first time that vegetation control on albedo during late spring and early summer has the highest potential to impact the degradation of permafrost. While both simulations show extensive near-surface permafrost degradation by the end of the twenty-first century, the strong projected response of vegetation to climate warming and increasing CO2 concentrations in the coupled simulation results in accelerated permafrost degradation in the northernmost continuous permafrost regions.

Ground temperature and permafrost distribution in Hurd Peninsula (Livingston Island, Maritime Antarctic): An assessment using freezing indexes and TTOP modelling

The Western Antarctic Peninsula region shows mean annual air temperatures ranging from −4 to −2°C. Due to its proximity to the climatic threshold of permafrost, and evidence of recent changes in regional air temperatures, this is a crucial area to analyse climate-ground interactions. Freezing indexes and n-factors from contrasting topographic locations in Hurd Peninsula (Livingston Island) are analysed to assess the influence of snow cover on soil's thermal regime. The snow pack duration, thickness and physical properties are key in determining the thermal characteristics and spatial distribution of permafrost. The Temperature at the Top Of the Permafrost (TTOP) model uses freezing and thawing indexes, n-factors and thermal conductivity of the ground, as factors representing ground-atmosphere interactions and provides a framework to understand permafrost conditions and distribution. Eight sites were used to calculate TTOP and evaluate its accuracy. They encompass different geological, morphological and climatic conditions selected to identify site-specific ground thermal regime controls. Data was collected in the freezing seasons of 2007 and 2009 for air, surface and ground temperatures, as well as snow thickness. TTOP model results from sites located between 140 and 275ma.s.l were very close to observational data, with differences varying from 0.05 to 0.4°C, which are smaller than instrumental error. TTOP results for 36ma.s.l confirm that permafrost is absent at low altitude and thermal offsets for rock areas show values between 0.01 and 0.48°C indicating a small effect of latent heat, as well as of advection.

Landscape Effects of Wildfire on Permafrost Distribution in Interior Alaska Derived from Remote Sensing

Climate change coupled with an intensifying wildfire regime is becoming an important driver of permafrost loss and ecosystem change in the northern boreal forest. There is a growing need to understand the effects of fire on the spatial distribution of permafrost and its associated ecological consequences. We focus on the effects of fire a decade after disturbance in a rocky upland landscape in the interior Alaskan boreal forest. Our main objectives were to (1) map near-surface permafrost distribution and drainage classes and (2) analyze the controls over landscape-scale patterns of post-fire permafrost degradation. Relationships among remote sensing variables and field-based data on soil properties (temperature, moisture, organic layer thickness) and vegetation (plant community composition) were analyzed using correlation, regression, and ordination analyses. The remote sensing data we considered included spectral indices from optical datasets (Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI)), the principal components of a time series of radar backscatter (Advanced Land Observing Satellite—Phased Array type L-band Synthetic Aperture Radar (ALOS-PALSAR)), and topographic variables from a Light Detection and Ranging (LiDAR)-derived digital elevation model (DEM). We found strong empirical relationships between the normalized difference infrared index (NDII) and post-fire vegetation, soil moisture, and soil temperature, enabling us to indirectly map permafrost status and drainage class using regression-based models. The thickness of the insulating surface organic layer after fire, a measure of burn severity, was an important control over the extent of permafrost degradation. According to our classifications, 90% of the area considered to have experienced high severity burn (using the difference normalized burn ratio (dNBR)) lacked permafrost after fire. Permafrost thaw, in turn, likely increased drainage and resulted in drier surface soils. Burn severity also influenced plant community composition, which was tightly linked to soil temperature and moisture. Overall, interactions between burn severity, topography, and vegetation appear to control the distribution of near-surface permafrost and associated drainage conditions after disturbance.

The Distribution, Thermal Characteristics and Dynamics of Permafrost in Tröllaskagi, Northern Iceland, as Inferred from the Distribution of Rock Glaciers and Ice‐Cored Moraines

ABSTRACTKnowledge of the characteristics and spatial distribution of permafrost in Iceland is important to understanding slope stability, climate change impacts and palaeo‐glaciology. The permafrost distribution there, however, is poorly constrained. The presence of rock glaciers and stable ice‐cored moraines in mountain settings relates to permafrost, making such landforms indicators of present or past permafrost. This study combines recently published aerial photographs (2002–07), radar interferometry based on Advanced Land Observing Satellite phased array type L‐band synthetic aperture radar (ALOS PALSAR) data (2007), land surface temperatures estimated from moderate‐resolution imaging spectroradiometer satellite data (MODIS; 2003–10) and field mapping to re‐examine the permafrost distribution, thermal characteristics and dynamics on the Tröllaskagi peninsula. An inventory of 265 landforms, mostly active or inactive (intact), categorised them by genesis and activity, the latter independently investigated by PALSAR interferometry. Intact landforms are mainly glacigenic, occurring as moraine‐derived rock glaciers or ice‐cored moraines. Their dominant orientation is between north and northeast, suggesting that topography and exposure influence their present‐day formation. Permafrost landforms exist at all elevations on the Tröllaskagi peninsula, with intact landforms at high elevations and relict landforms reaching down to sea level. Rock glaciers at sea level may imply early deglaciation of northern Iceland. Copyright © 2013 John Wiley & Sons, Ltd.

Distribution and characterization of soils and landform relationships in Byers Peninsula, Livingston Island, Maritime Antarctica

This paper presents the spatial distribution of soils from the northern part of Byers Peninsula, Livingston Island, which is the largest ice-free area of the South Shetlands archipelago, Maritime Antarctica. Physical and chemical characteristics are presented for 23 soil profiles. Soil parent materials vary from marine sedimentary to volcanic and volcanoclastic rocks, intruded by igneous bodies. To assess soil–landscape relationships, twenty-three soil profiles were described and sampled. Soil samples of selected horizons were submitted to chemical, physical and mineralogical analyses. Soil mapping was based on the soil profiles, integrated with the existent topographic map (1:25.000 scale), a digital elevation model, the geological map and a satellite image. Twenty different soil units were identified and mapped. According to the World Reference Base for Soil Resources (WRB) system, soils were classified as Fluvisols, Regosols, Leptosols or Cryosols, which correspond mostly to Fluvents, Orthents/Psamments, Inceptsols and Gelisols, respectively, according to the Soil Taxonomy. Soils from northern Byers Peninsula are generally shallow and coarse textured, with low organic matter content. Three soils from the rocky platforms of the northern coastal region possess ornithogenic character, with lower pH, higher P, Al3+ and organic C values when compared to soils not influenced by sea birds. In non-ornithogenic soils, the presence of easily weatherable minerals in the clay fraction indicates that physical weathering occurs with limited chemical alteration of primary minerals. The influence of penguin and other birds on coastal soils alters clay mineralogy, with formation of poorly crystalline P-rich phases. A better understanding of the depth of the permafrost table and the spatial distribution of permafrost is necessary for a more conclusive classification of Cryosols or Gelisols.

Using the MODIS land surface temperature product for mapping permafrost: an application to northern Québec and Labrador, Canada

AbstractThe Land Surface Temperature (LST) products of the Moderate Resolution Imaging Spectroradiometers (MODIS) aboard NASA's Terra and Aqua satellites were used to develop maps of annual near‐surface temperatures for comparison with the spatial distribution of permafrost and boundaries of the permafrost zones. The methodological approach involved fitting a sinusoidal model over the daily LST readings to reproduce seasonal thermal variations near the ground for each 1‐km2 pixel. Calculations of mean annual surface temperatures and of thawing and freezing indices led to the development of regional maps, in this case for northern Québec and Labrador. The maps show the expected geographic distribution of near‐surface temperatures and acceptably represent known permafrost boundaries. Ongoing efforts to incorporate snow and vegetation cover from complementary remotely sensed data should improve the ground surface temperature mapping capability based on this approach. Copyright © 2009 John Wiley & Sons, Ltd.

Impact of permafrost change on the Qinghai-Tibet Railroad engineering

Permafrost along the Qinghai-Tibet Railroad produces the great change under the influence of climate change, such as the decreasing of permafrost table, the rising of permafrost temperatures, etc. Climate effect on permafrost is the long-term process. Engineering action makes rapidly permafrost the large extent change. On the basis of analyzing the permafrost change under the climate change and engineering action, the thermal regime and spatial distribution of permafrost are predicted for air temperature rising 1°C and 2 °C after 50 years in this paper. The results show that climate change results in the larger change for the thermal regime and spatial distribution of permafrost. Permafrost change will produce the great effect on the Qinghai-Tibet Railroad engineering, not only resulting in the decreasing of permafrost table beneath the roadbed, but also resulting in thawing settlement due to the thawing of ground ice near permafrost table. The idea of cooling roadbed and active protecting permafrost for the Qinghai-Tibet Railroad engineering could adjust and control the permafrost thermal state, some better methods are provided to ensure the engineering stability in the areas of warm permafrost and high ice content.

Modelling alpine permafrost distribution, Val de Rechy, Valais Alps (Switzerland)

The spatial distribution of the alpine permafrost is modelled in the uppermost part of Val de Rechy (Valais Alps, Switzerland) with the use of a geographical information system (GIS). Two empirical-statistical models are compared and their validity tested by a set of bottom temperature of winter snow (BTS) measurements carried out in the field. One model can simulate the spatial distribution of the permafrost facing ground warming consecutive to climatic change. Local/regional maps of simulated permafrost distribution as presented in this paper can be useful in the context of a preventive approach for natural hazards management.

Long-Term Monitoring of Permafrost Change in a Palsa Peatland in Northern Quebec, Canada: 1983-1993

Changes in the spatial distribution of permafrost in the Ouiatchouane palsa peatland (northern Quebec) were monitored from 1957 to present, using aerial photographs taken in 1957 (starting date) and three field surveys in 1973, 1983, and 1993, respectively. Between 1983 and 1993, palsa degradation occurred at about the same rate as between 1957 and 1983, although minor differences in rate of permafrost decay during the three periods (1957-1973, 1973-1983, 1983-1993) may be attributed in part to misidentification of marginal permafrost landforms. Permafrost degradation appeared to be influenced by height of individual palsas and their location within the peatland. Since 1983, thermokarst ponds have been progressively invaded by sedges and Sphagnum, a situation promoting successional peatland development and palsa formation as suggested by the presence of a small incipient palsa. Although the main geomorphic process at work is palsa degradation, permafrost aggradation is possible under present climatic conditions. 28 refs., 3 figs., 1 tab.

Détermination de la géométrie et des propriétés physiques du pergélisol discontinu de la région de Schefferville

The various parameters used to predict on a regional scale the lateral and vertical extension of permafrost are the following: surface temperature, thermal conductivity of rocks, and geothermal flow configuration. Locally this type of data is generally not sufficient and far too inaccurate. The use of geophysical methods at the surface and in boreholes in addition to existing thermal data helps to improve the degree of accuracy in the prediction of spatial distribution of permafrost in a given area. These geophysical methods include seismic refraction, electrical resistivity, and spontaneous and induced polarizations.Because of the properties of permafrost, seismic refraction at surface is useful only to determine the top of the permafrost whereas electrical resistivity (electric logging near surface) allows the determination of the upper and lower limits of permafrost. Seismic refraction, resistivity, and spontaneous and induced polarizations in boreholes were deemed more promising to determine masses or lenses of permafrost.Moreover, it was possible to correlate temperature and electrical resistivity measurements in boreholes, thus allowing the drawing of isothermal curves from electric logging in areas of continuous and discontinuous permafrost, at least when it is 'marginal'.The data for this study were obtained from the experimental station at Schefferville, Québec. [Journal Translation]