Permafrost Type Research Articles

Regional Analysis of NASA Satellite Greenness Trends for Ecosystems of Arctic Alaska

Trends in the growing season MODerate resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time-series were analyzed for the period from 2000 to 2010 to understand landscape-level patterns of vegetation change in ecosystems of arctic Alaska. We compared datasets for vegetation cover types, wetland cover classes, wildfire boundaries since the 1940s, permafrost type, and elevation to identify the most likely combination of factors driving regional changes in habitat quality and ecosystem productivity. Approximately 57% of all arctic ecosystem areas in Alaska were detected with significant (p 2) were detected with significant positive growing season EVI trends. The vast majority of the arctic Alaska region detected with significant positive growing season EVI trends was classified as upland tundra cover, although non-forested wetlands (marshes, bogs, fens, and floodplains) were co-located on 8% of that area. Herbaceous wetlands were co-located on 55% of the total area detected with significant negative growing season EVI trends, mostly on the arctic coastal plain and foothills. This evidence supports the hypothesis that temperature (warming) has markedly enhanced the rates of upland tundra vegetation growth across most of arctic Alaska over recent years.

Lake variations in response to climate change in the Tibetan Plateau in the past 40 years

The Qinghai-Tibetan Plateau plays an important role in global climate and environmental change and holds the largest lake area in China, with a total surface area of 36,900 km2. The expansion and shrinkage of these lakes are critical to the water cycle and ecological and environmental systems across the plateau. In this paper, surface areas of major lakes within the plateau were extracted based on a topographic map from 1970, and Landsat MSS, TM and ETM+ satellite images from the 1970s to 2008. Then, a multivariate correlation analysis was conducted to examine the relationship between the changes in lake surface areas and the changes in climatic variables including temperature, precipitation, evaporation, and sunshine duration. Initial results suggest that the variations in lake surface areas within the plateau are closely related to the warming, humidified climate transition in recent years such as the rise of air temperature and the increase in precipitation. In particular, the rising temperature accelerates melting of glaciers and perennial snow cover and triggers permafrost degradation, and leads to the expansion of most lakes across the plateau. In addition, different distributions and types of permafrost may cause different lake variations in the southern Tibetan Plateau.

Constraining spatial variability of methane ebullition seeps in thermokarst lakes using point process models

AbstractEbullition is an important but highly heterogeneous mode of methane emission in lakes. Variability in both spatial distribution and temporal flux creates difficulty in constraining uncertainties in whole lake emission estimates. Analysis of short‐ and long‐term flux measurements on 162 ebullition seeps in 24 panarctic lakes confirmed that seep classes, identified a priori according to bubble patterns in winter lake ice, have distinct associated fluxes irrespective of lake or region. To understand the drivers of ebullition's spatial variability and uncover ways to better quantify ebullition in field work, we combined point‐process modeling with field measurements of 2679 GPS‐marked and classified ebullition seeps in three Alaskan thermokarst (thaw) lakes that varied by region, permafrost type, and seep distribution. Spatial analysis of field data revealed that seeps cluster above thawed permafrost soil mounds in lake bottoms. Seep density and clustering, determined from field observations, were used as parameters in a Poisson cluster process model to simulate seeps across entire lake surfaces. Sampling results indicated that (1) applying seep‐class mean flux values to unmeasured seeps counted on ice‐bubble surveys does not compromise accuracy of whole lake flux estimates; (2) three distributed 50 m2 ice‐bubble survey transects more accurately estimate mean lake ebullition than 17 dispersed 0.2 m2 bubble traps; and (3) the uncertainty associated with whole lake mean ebullition estimated by lake‐ice survey transects is inversely related to seep density. Findings suggest that transect field data collected on a large number of widely distributed lakes can be combined to provide a well‐constrained, bottom‐up estimate of regional lake ebullition.

Application of electrical resistivity tomography in investigating depth of permafrost base and permafrost structure in Tibetan Plateau

Abstract The changes in the thickness of permafrost and the distribution characteristics of ground ice are of great importance for engineering and environmental issue research in permafrost regions. This study was conducted in the permafrost observation field in Qumahe in the east of the Tibetan Plateau by using electrical resistivity tomography (ERT) for investigating the depth of permafrost base and the structure of permafrost. The results demonstrated that the ERT can detect the depth of permafrost base, identify the characteristics of ground ice and the variation of permafrost types in Qumahe. Also, the effects and accuracy of ERT were evaluated combining the information provided by borehole and ground temperature monitoring. The comprehensive analysis of the data shows that the distribution of permafrost and ground ice in this area is strongly influenced by geographical, topographical and other local factors. The depth of the permafrost base within the observation field differs by 30 m. Aspect, surface water and vegetation conditions have the most significant influence on the thickness of permafrost. A seasonal stream in the low-lying area of the observation field also brings strong influence to permafrost thermal disturbance and thickness. Meanwhile, different geomorphic unit and surface conditions significantly influence the development of ground ice. To be specific, the massive ground ice is mainly developed in the flat swamping wetland, especially the low-lying wetland. In terms of depth, the massive ground ice is mainly developed within 5 to 10 m below the permafrost table.

Response characteristics of vegetation and soil environment to permafrost degradation in the upstream regions of the Shule River Basin

Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai–Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial–temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1) ST of 0–40 cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0–20 cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2) further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3) in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP) to transitional (TP), and to UP. Meanwhile, SOC/TN storages increased in the former stage, while they decreased in the latter stage. This study indicated that the response characteristics of vegetation and soil environment varied throughout the entire permafrost degradation, and SW was the dominant ecological factor that limited vegetation distribution and growth. Therefore, SSP and TP phases could provide a favourable environment for plant growth, mainly contributing to high SW.

Temporal and spatial variations of the active layer along the Qinghai-Tibet Highway in a permafrost region

Using monitored active layer thickness (ALT) and environmental variables of 10 observation fields along the Qinghai-Tibet Highway in permafrost region of the Qinghai-Tibetan Plateau (QTP), a model for ALT estimation was developed. The temporal and spatial characteristics of the ALT were also analyzed. The results showed that in the past 30 years ALT in the study region increased at a rate of 1.33 cm a−1. Temperatures at the upper limit of permafrost and at 50 cm depth, along with soil cumulative temperature at 5 cm depth also exhibited a rising trend. Soil heat flux increased at a rate of 0.1 W m−2 a−1. All the above changes demonstrated that the degradation of permafrost happened in the study region on the QTP. The initial thawing date of active layer was advanced, while the initial freezing date was delayed. The number of thawing days increased to a rate of 1.18 d a−1. The variations of active layer were closely related to the permafrost type, altitude, underlying surface type and soil composition. The variations were more evident in cold permafrost region than in warm permafrost region, in high-altitude region than in low-altitude region, in alpine meadow region than in alpine steppe region; and in fine-grained soil region than in coarse-grained soil region.

Pedogenesis, permafrost, and soil moisture as controlling factors for soil nitrogen and carbon contents across the Tibetan Plateau

AbstractWe investigated the main parameters [e.g. mean annual air temperature , mean annual soil temperature, mean annual precipitation, soil moisture (SM), soil chemistry, and physics] influencing soil organic carbon (Corg), soil total nitrogen (Nt) as well as plant available nitrogen (Nmin) at 47 sites along a 1200 km transect across the high‐altitude and low‐latitude permafrost region of the central‐eastern Tibetan Plateau. This large‐scale survey allows testing the hypothesis that beside commonly used ecological variables, diversity of pedogenesis is another major component for assessing carbon (C) and nitrogen (N) cycling. The aim of the presented research was to evaluate consequences of permafrost degradation for C and N stocks and hence nutrient supply for plants, as the transect covers all types of permafrost including heavily degraded areas and regions without permafrost. Our results show that SM is the dominant parameter explaining 64% of Corg and 60% of N variation. The extent of the effect of SM is determined by permafrost, current aeolian sedimentation occurring mostly on degraded sites, and pedogenesis. Thus, the explanatory power for C and N concentrations is significantly improved by adding CaCO3 content (P=0.012 for Corg; P=0.006 for Nt) and soil texture (P=0.077 for Corg; P=0.015 for Nt) to the model. For soil temperature, no correlations were detected indicating that in high‐altitude grassland ecosystems influenced by permafrost, SM overrides soil temperature as the main driving parameter at landscape scale. It was concluded from the current study that degradation of permafrost and corresponding changes in soil hydrology combined with a shift from mature stages of pedogenesis to initial stages, have severe impact on soil C and plant available N. This may alter biodiversity patterns as well as the development and functioning of the ecosystems on the Tibetan Plateau.

Indicators of present global warming through changes in active layer-thickness, estimation of thermal diffusivity and geomorphological observations in the Morenas Coloradas rockglacier, Central Andes of Mendoza, Argentina

Abstract Temperature profiles from the active layer have been analysed for 2 sites on the composed rockglacier Morenas Coloradas, Cordon del Plata, Mendoza, Argentina, using monitoring data collected between 1989 and 2008 in order to characterize the impact of global warming in the cryolithozone of the Dry Andes at these latitudes (32°–33° S). A significant change in the active layer and suprapermafrost of this rockglacier of the Cordon del Plata is registered at the monitoring sites. The observed changes imply direct consequences for the cryogenic environment and the Andean creeping permafrost . The nose of the Morenas Coloradas rockglacier for example (Balcon I, 3560 m a.s.l.), already expresses inactivity; the permafrost table is found at great depth (7.5–9 m). Data collected at Balcon I and II allow to estimate the theoretical thermal diffusivity α at the active layer of Morenas Coloradas. Thermal diffusivity may be decisive for the study of cryogenic dynamics at other altitudes and latitudes in the region where data are still scarce. Low α values ( − 6 m 2 /s) correlate with occurrence of freezing and ice at low altitudes. While the glaciers are turning into small insignificant bodies in the high mountains, the periglacial level with creeping permafrost and linked with rockglaciers is expanding altitudinally, passing a transitional “rooting” area which is indirectly feeding the rockglaciers with their covered or “dead ice”. The ice of glacigenic origin contributes to the genesis of this type of permafrost. As the permafrost table is found at greater depths, the rockglaciers need to be monitored in order to define a balance between the upper periglacial level (in terms of altitude) with mountain continuous–quasi continuous permafrost and the lower periglacial level to where the lowest fronts of creeping permafrost are reaching. The variations of the cryogenic structure of the rockglaciers of the Cordon del Plata caused by warming processes, will have direct consequences for the volume of frozen sediments and therefore for the hydrology of the entire region, a fact that has to be taken into account for future socio-economic programs of the respective provincial governments.

Distribution of Glacial Deposits, Soils, and Permafrost in Taylor Valley, Antarctica

ABSTRACTWe provide a map of lower and central Taylor Valley, Antarctica, that shows deposits from Taylor Glacier, local alpine glaciers, and grounded ice in the Ross Embayment. From our electronic database, which includes 153 sites from the coast 50 km upvalley to Pearse Valley, we show the distribution of permafrost type and soil subgroups according to Soil Taxonomy. Soils in eastern Taylor Valley are of late Pleistocene age, cryoturbated due to the presence of ground ice or ice-cemented permafrost within 70 cm of the surface, and classified as Glacic and Typic Haploturbels. In central Taylor Valley, soils are dominantly Typic Anhyorthels of mid-Pleistocene age that have dry-frozen permafrost within the upper 70 cm. Salt-enriched soils (Salic Anhyorthels and Petrosalic Anhyorthels) are of limited extent in Taylor Valley and occur primarily on drifts of early Pleistocene and Pliocene age. Soils are less developed in Taylor Valley than in nearby Wright Valley, because of lesser salt input from atmospheric deposition and salt weathering. Ice-cemented permafrost is ubiquitous on Ross Sea, pre–Ross Sea, and Bonney drifts that occur within 28 km of the McMurdo coast. In contrast, dry-frozen permafrost is prevalent on older (≥115 ky) surfaces to the west.

Visualising cryospheric images in a virtual environment: present challenges and future implications

ABSTRACTThe United States National Snow and Ice Data Center (NSIDC) initiated an outreach project to enhance the visibility of and interest in cryospheric images. Methods were utilised to convert cryospheric data into a projection and image format compatible with Google Earth™. The word ‘image’ should be emphasised since raster data in a native polar projection and format cannot be overlaid on the Earth without prior data conversions. The project focused on reaching out to a diverse audience by integrating images from key components of the cryosphere into a single compressed Keyhole Markup Language (KMZ) file. As a result, users can visualise glacier photographs, permafrost type and extent, sea ice concentration and extent, and snow extent superimposed on the Earth. Those interested in browsing the NSIDC collection of over 3,000 glacier photographs have the option of zooming into Alaska for a majority of the images and accessing both the photograph and the associated metadata. For a current perspective of global snow and ice coverage, one could look at satellite imagery derived from passive microwave Special Sensor Microwave/Imager (SSM/I) data. Another option is to select the permafrost layer and observe the various types and extent of permafrost. This paper explores the project by describing the data, methodologies and results and concludes with future implications on how to improve the processing and functionality of polar data in Google Earth.

Thermal regimes and degradation modes of permafrost along the Qinghai-Tibet Highway

Permafrost on the Qinghai-Tibet Plateau (QTP) is widespread, thin, and thermally unstable. Under a warming climate during the past few decades, it has been degrading extensively with generally rising ground temperatures, the deepening of the maximum summer thaw, and with lessening of the winter frost penetration. The permafrost has degraded downward, upward and laterally. Permafrost has thinned or, in some areas, has totally disappeared. The modes of permafrost degradation have great significance in geocryology, in cold regions engineering and in cold regions environmental management. Permafrost in the interior of the QTP is well represented along the Qinghai-Tibet Highway (QTH), which crosses the Plateau through north to south and traverses 560 km of permafrost-impacted ground. Horizontally, the degradation of permafrost occurs more visibly in the sporadic permafrost zone in the vicinity of the lower limit of permafrost (LLP), along the margins of taliks, and around permafrost islands. Downward degradation develops when the maximum depth of seasonal thaw exceeds the maximum depth of seasonal frost, and it generally results in the formation of a layered talik disconnecting the permafrost from the seasonal frost layer. The downward degradation is divided into four stages: 1) initial degradation, 2) accelerated degradation, 3) layered talik and 4) finally the conversion of permafrost to seasonally frozen ground (SFG). The upward degradation occurs when the geothermal gradient in permafrost drops to less than the geothermal gradients in the underlying thawed soil layers. Three types of permafrost temperature curves (stable, degrading, and phase-changing transitory permafrost) illustrate these modes. Although strong differentiations in local conditions and permafrost types exist, the various combinations of the three degradation modes will ultimately transform permafrost into SFG. Along the QTH, the downward degradation has been proceeding at annual rates of 6 to 25 cm, upward degradation at 12 to 30 cm, and lateral degradation in the sporadic permafrost zone at 62 to 94 cm during the last quarter century. These rates exceed the 4 cm per year for the past 20 years reported for the discontinuous permafrost zone in subarctic Alaska, the 3 to 7 cm per year reported in Mongolia, and that of the thaw-stable permafrost in subarctic Yakutia and Arctic Alaska.

Permafrost properties, patterns and processes in the Transantarctic Mountains region

The properties, distribution patterns and thermal processes that influence the active layer and permafrost in the Transantarctic Mountains region of Antarctica, as deduced from our soil investigations since 1964 and drilling investigations since 1990, are outlined. The active layer depth varies from around 80 cm thick in coastal areas to <5 cm in inland and upland regions, due to the effect of the adiabatic lapse rate. Saline, ice-bonded, dry permafrost and transitional types of permafrost all occur. Ice content is highest in ice-bonded permafrost of the coastal regions and lowest in inland dry permafrost where values may be <1%. At the regional scale, ice-bonded permafrost most commonly occurs at lower elevations and beneath younger land surfaces but with increasing elevation, distance inland and land surface age, dry permafrost becomes predominant. At the local scale (<1 m) there are large variations in the depth to the permafrost table due to variations in ground surface features. Permafrost properties are largely governed by solar energy receipt, but albedo, air temperature cooling and available soil moisture strongly modulate the conversion of solar energy receipt into soil heating. These factors account for the considerable broad-scale and local variability in permafrost properties that exists. Copyright © 2006 John Wiley & Sons, Ltd.

Syngenetic permafrost growth: cryostratigraphic observations from the CRREL tunnel near Fairbanks, Alaska

AbstractSyngenetic permafrost forms when alluvial, aeolian and/or colluvial sediment accumulates under cold‐climate conditions. Observations from within the CRREL permafrost tunnel near Fairbanks, Alaska, indicate that layered, lenticular‐layered and micro‐lenticular cryogenic structures are characteristic of this type of permafrost. In contrast, reticulate cryogenic structures indicate local thaw modification. During the growth of syngenetic permafrost, episodes of thermokarst erosion may operate preferentially along ice wedges leading to the development of gullies and tunnels in the near‐surface sediments. The local thaw unconformities that result are inferred by the recognition of thermokarst‐cave ice (‘pool’ ice), and various soil and ice pseudomorphs. These may be regarded as further characteristics of syngenetic permafrost growth. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Enlarged Base (Belled) Piles for Use in Ice or Ice-Rich Permafrost

The influence of enlarging the base of a pile on the total and end bearing capacities of a pile in ice-rich permafrost is evaluated along with the principles used to evaluate the total capacity of uniform diameter and belled piles of the same length in ice-rich soils. Procedures developed by Weaver and Morgenstern in 1981 for predicting the total capacity of straight piles are extended to predict the capacity of belled piles to study the capacity of enlarging the pile base. The total capacity can be substantially improved through the use of belled piles. Techniques to form the bell in different types of permafrost are reviewed with an emphasis on jet cutting. The techniques to allow for installation are described as well as the need for field tests to confirm the proposed installation technique and the predicted increased capacity.

Characteristics of earth hummocks (pounus) with and without permafrost in finnish lapland

Finnish Lapland north of 68°30′N latitude is located in the zone of discontinuous permafrost. Two main types of permafrost have previously been found in northern Finland: palsas in the mires and frost in the bedrock on the barren fell summits. The aim of this study was (1) to investigate permafrost occurrence in the peaty earth hummocks (pounus) in several mires, and (2) model characteristics of pounus with and without permafrost.This study showed that permafrost in Finnish Lapland occurs much more widely and commonly than was previously known. A total of 59% of the studied pounus were found to contain permafrost. Over 90% of the permafrost occurrence in the pounus was correctly classified in logistic regression modelling. The probability of permafrost in a pounu decreased with the height of vegetation, and increased with the pounu height and distance from the running stream. There were clear vegetation differences between pounus with and without permafrost. Unfrozen pounus are characterized by forest and mire species, whereas on the permanently frozen pounus the vegetation is patchier with species indicating drier conditions. Pounus provide an excellent object to study short–term and local variations in permafrost formation due to their small size. They react quickly to variation in temperature, snow depth and precipitation. We conclude that pounus can be classified as sporadic permafrost features in northernmost Europe under modern climatic conditions.

Permafrost as a climatic indicator in northern Victoria Land, Antarctica

AbstractKnowledge of permafrost characteristics and distribution in Antarctica and their relationships with present and past climates is still poor. This paper reports investigations on permafrost in an area located between Nansen Ice Sheet to the south and Mount Melbourne (2732 m a.s.l.) to the north. Investigation methods included geomorphological surveys and geoelectrical soundings as well as crystallography, chemical and isotopic analyses of the ground ice. Geomorphological surveys helped to explain the relationships between periglacial landforms (e.g. rock glaciers and patterned ground) and the glacial history of the area. Geoelectrical soundings allowed us to define different ground-ice units in the ice-free areas. Each unit was characterised by a different type of permafrost (dry or ice-poor permafrost, marine or continental massive buried ice and sub-sea permafrost). To identify the nature of ground ice, trenches were dug and some shallow boreholes were drilled to a maximum depth of-3.6 m in massive buried ice. Samples of both ice-poor permafrost and massive ice were collected and analyzed. Chemical, isotopic δ18O and crystal analyses were also carried out. The relationships between climate and thermal regimes of the active layer and the upper part of permafrost were determined using a monitoring station for ground temperatures at Boulder Clay Glacier, near the Italian Antarctic station. During winter, there were several significant thermal-inversion events in the ground, which cannot be explained only by air-temperature changes, suggesting a possible influence of winter snowfall, even if these events are usually considered very rare.

Methods of calculating thawing and freezing in beds of structures on nonflowing types of permafrost : G. P. Pustovoit, Soil Mechanics & Foundation Engineering, 32(2), 1995, pp 57–62; translated from: Osnovaniya, Fundamenty i Mekhanika Gruntov, 2, 1995, pp 18–22

Methods of calculating thawing and freezing in beds of structures on nonflowing types of permafrost : G. P. Pustovoit, Soil Mechanics & Foundation Engineering, 32(2), 1995, pp 57–62; translated from: Osnovaniya, Fundamenty i Mekhanika Gruntov, 2, 1995, pp 18–22

Methods of calculating thawing and freezing in beds of structures on nonflowing types of permafrost

The causes of and conditions for the manifestation of distortions in calculations conducted by the method of auxiliary temperatures are exposed. It is indicated that the distortions are maximum beneath the edges of structures, where the design frost depth may be on the low side by a factor of two and more. A computational method, which is free of exposed drawbacks and which indicates agreement with the results of numerical modeling is developed, proceeding from analytical solution of the problem of the motion of the phase interface in quasi-stationary approximation.

Effect of permafrost conditions and type of foundations on deformation of building in Vorkuta

Effect of permafrost conditions and type of foundations on deformation of building in Vorkuta

Offshore Permafrost and Ground Ice, Southern Beaufort Sea, Canada

The distribution and origin of offshore permafrost is discussed for the southern Beaufort Sea. Two types of permafrost are identified: permafrost which is in thermal equilibrium with negative sea bottom temperatures, and disequilibrium permafrost, which is not in equilibrium with either positive or negative sea bottom temperatures. The origin of permafrost is considered in terms of the Quaternary period when coastal areas were exposed to cold air temperatures and then submerged. The effect of warm river waters, primarily from the Mackenzie River, is shown to ameliorate coastal water temperatures and may be responsible for a thin active layer at some sites. Water quality and oxygen isotope ratios are given for some samples. The evidence suggests that some relic land permafrost, with ground ice, is present beneath the southern Beaufort Sea. Perforated permafrost should be present, but not extensive thermokarst depressions. By inference, permafrost probably underlies much of the Canadian Arctic waters, although ground ice is likely restricted to a relatively few shallow coastal zones.