Lake- and channel-bottom temperatures in the Mackenzie Delta, Northwest Territories1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Project Contribution 03511.

2012 ◽  
Vol 49 (8) ◽  
pp. 963-978 ◽  
Author(s):  
T.P. Ensom ◽  
C.R. Burn ◽  
S.V. Kokelj
Keyword(s):  
Applied Research ◽  
Spatial And Temporal Variation ◽  
Mackenzie Delta ◽  
Special Issue ◽  
Bottom Temperature ◽  
Channel Network ◽  
Near Surface ◽  
Ground Temperatures ◽  
Hydrologic System ◽  
Channel Bottom

Temperature loggers were placed in 17 lakes and 13 channels throughout the Mackenzie Delta to determine the annual mean bottom temperature ([Formula: see text]) and its spatial and temporal variation for June 2009 – June 2010. The lakes were classified as perched or connected, depending on the duration of their connection to the channel hydrologic system. Average [Formula: see text] values for nine perched lakes, five channels, and eight connected lakes distributed throughout the Mackenzie Delta were 5.5, 4.6, and 3.4 °C, respectively. The range of [Formula: see text] among all instrumented water bodies in the Delta was 4.0 °C. Over the year, bottom temperatures ranged from >20 °C in midsummer to –5 °C in midwinter, with relative stability between freeze-up in mid-October and breakup at the beginning of June. Channel, perched, and connected lake [Formula: see text], and mean annual near-surface ground temperatures of –4 °C in alluvial sedge wetlands and –2.25 °C in forest, were used to estimate that about 60% of Delta lakes and nearly the entire channel network maintain through-taliks.

Factors influencing permafrost temperatures across tree line in the uplands east of the Mackenzie Delta, 2004–20101This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Contribution 03611.

2012 ◽  
Vol 49 (8) ◽  
pp. 877-894 ◽  
Author(s):  
M.J. Palmer ◽  
C.R. Burn ◽  
S.V. Kokelj
Keyword(s):  
Snow Depth ◽  
Applied Research ◽  
Abrupt Change ◽  
Late Winter ◽  
Mackenzie Delta ◽  
Near Surface ◽  
Ground Temperatures ◽  
Winter Snow ◽  
Shrub Tundra ◽  
Snow Conditions

Air and near-surface ground temperatures, late-winter snow conditions, and characteristics of the vegetation cover and soil were measured across the forest–tundra transition in the uplands east of the Mackenzie Delta, Northwest Territories, in 2004–2010. Mean late-winter snow depth decreased northward from 73 cm in the subarctic boreal forest near Inuvik to 22 cm in low-shrub tundra. Annual near-surface ground temperatures decreased northward by 0.1–0.3 °C/km near the northern limit of trees, in association with an abrupt change in snow depth. The rate decreased to 0.01–0.06 °C/km in the tundra. The freezing season is twice as long as the thawing season in the region, so measured differences in the regional ground thermal regime were dominated by the contrast in winter surface conditions between forest and tundra.

Influence of snow on near-surface ground temperatures in upland and alluvial environments of the outer Mackenzie Delta, Northwest Territories1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.

2012 ◽  
Vol 49 (8) ◽  
pp. 895-913 ◽  
Author(s):  
P.D. Morse ◽  
C.R. Burn ◽  
S.V. Kokelj
Keyword(s):  
Snow Cover ◽  
Active Layer ◽  
Snow Depth ◽  
Active Layer Thickness ◽  
Mackenzie Delta ◽  
Diverse Range ◽  
Near Surface ◽  
Ground Temperatures ◽  
Vegetation Height ◽  
The Difference

Relations between snow cover, active-layer thickness, and near-surface ground temperatures were determined in 2005–2009 for a diverse range of alluvial and upland settings in the outer Mackenzie Delta. Here, the snow cover developed primarily by wind redistribution, with its spatial variation controlled by topography in uplands and vegetation height in alluvial lowlands. Snow cover was the primary influence on freeze-back duration and the mean annual temperature at the top of permafrost (TTOP), with the difference in median TTOP between alluvial (–3.7 °C) and upland (–6.1 °C) settings related to the greater snow depth and soil moisture in the alluvial plain. The active layer was generally deeper in the wet alluvial lowlands, where the average duration of active-layer freeze back (101 days) was nearly double the time taken in the well-drained uplands (55 days). The surface offset (ΔTS; up to 11 °C) dominated the difference between annual mean air temperature (AMAT) and TTOP (ΔT). In alluvial terrain, ΔTS varied with snow depth, but in the uplands, ΔTS was more consistent from site to site. The small thermal offset (<2 °C) was slightly greater in alluvial terrain than in the uplands. The overall range in ΔT (2–10 °C) led to a range during the study of 7.2 °C in TTOP at the sites. The range in AMAT was 1.3 °C but up to 1.7 °C in TTOP at any one site. Permafrost was well established throughout the area except adjacent to channels where TTOP was close to 0 °C.

scholarly journals Microtopographic control on the ground thermal regime in ice wedge polygons

2018 ◽  
Vol 12 (6) ◽  
pp. 1957-1968 ◽  
Author(s):  
Charles J. Abolt ◽  
Michael H. Young ◽  
Adam L. Atchley ◽  
Dylan R. Harp
Keyword(s):  
Thermal Conditions ◽  
Ground Temperature ◽  
The Arctic ◽  
Near Surface ◽  
Hydrologic Processes ◽  
Ground Temperatures ◽  
Air Temperatures ◽  
Winter Temperatures ◽  
Ice Wedge ◽  
Prudhoe Bay

Abstract. The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 ∘C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.

scholarly journals Imaging Thermal Anomalies in Hot Dry Rock Geothermal Systems from Near-Surface Geophysical Modelling

2019 ◽  
Vol 11 (6) ◽  
pp. 675 ◽  
Author(s):  
David Gomez-Ortiz ◽  
Isabel Blanco-Montenegro ◽  
Jose Arnoso ◽  
Tomas Martin-Crespo ◽  
Mercedes Solla ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Electromagnetic Induction ◽  
Hydrothermal Systems ◽  
Ground Temperature ◽  
Geothermal Systems ◽  
Near Surface ◽  
Hot Dry Rock ◽  
Ground Temperatures ◽  
Imaging Results ◽  
Ground Penetrating

Convective hydrothermal systems have been extensively studied using electrical and electromagnetic methods given the strong correlation between low conductivity anomalies associated with hydrothermal brines and high temperature areas. However, studies addressing the application of similar geophysical methods to hot dry rock geothermal systems are very limited in the literature. The Timanfaya volcanic area, located on Lanzarote Island (Canary Islands), comprises one of these hot dry rock systems, where ground temperatures ranging from 250 to 605 °C have been recorded in pyroclastic deposits at shallow (<70 m) depths. With the aim of characterizing the geophysical signature of the high ground temperature areas, three different geophysical techniques (ground penetrating radar, electromagnetic induction and magnetic prospecting) were applied in a well-known geothermal area located inside Timanfaya National Park. The area with the highest ground temperatures was correlated with the location that exhibited strong ground penetrating radar reflections, high resistivity values and low magnetic anomalies. Moreover, the high ground temperature imaging results depicted a shallow, bowl-shaped body that narrowed and deepened vertically to a depth greater than 45 m. The ground penetrating radar survey was repeated three years later and exhibited subtle variations of the signal reflection patterns, or signatures, suggesting a certain temporal variation of the ground temperature. By identifying similar areas with the same geophysical signature, up to four additional geothermal areas were revealed. We conclude that the combined use of ground penetrating radar, electromagnetic induction and magnetic methods constitutes a valuable tool to locate and study both the geometry at depth and seasonal variability of geothermal areas associated with hot dry rock systems.

scholarly journals Editorial for the Special Issue “Innovative and Applied Research on Platinum-Group and Rare Earth Elements”

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 493
Author(s):  
Maria Economou-Eliopoulos ◽  
Federica Zaccarini ◽  
Giorgio Garuti
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Applied Research ◽  
Mineral Exploration ◽  
Special Issue ◽  
Platinum Group

This Special Issue “Innovative and Applied Research on Platinum-group and Rare Earth Elements” is dedicated to the work and memory of Demetrios Eliopoulos, IGME (Institute of Geology and Mineral Exploration), Greece who passed away on 19 April 2019 [...]

Cessation of ice-wedge development during the 20th century in spruce forests of eastern Mackenzie Delta, Northwest Territories, Canada

2007 ◽  
Vol 44 (11) ◽  
pp. 1503-1515 ◽  
Author(s):  
S V Kokelj ◽  
M FJ Pisaric ◽  
C R Burn
Keyword(s):  
20Th Century ◽  
Ice Age ◽  
Spruce Forest ◽  
Mackenzie Delta ◽  
Study Region ◽  
Near Surface ◽  
Spruce Forests ◽  
Surface Temperatures ◽  
Forest Sites ◽  
Ice Wedge

Ice wedges are presently inactive in white spruce (Picea glauca) forests of eastern Mackenzie Delta as shown by the absence of vein ice above ice wedges, the maintenance of intact breaking cables, and the abundance of rootlets propagating across ridge–trough sequences. At spruce forest sites, near-surface ground cooling rates and minimum near-surface temperatures from the years 2003–2005 were above ice-wedge cracking thresholds. Ground thermal conditions associated with cracking were recorded at a tundra peatland with active ice wedges. Annual mean permafrost temperatures at the spruce forest sites ranged from –1.8 to –2.9 °C, whereas at the tundra peatland, the permafrost was colder than –6 °C. Although winter air temperatures are similar throughout the study region, deeper snow cover, thicker active layers, and warmer permafrost account for the more gradual seasonal cooling and warmer near-surface temperatures recorded at the subarctic forest sites. The subtle ridge to trough relief, 12–35 cm of permafrost above wedge ice, roots up to 80 years old grown across ice wedges, and negligible tritium levels in wedge ice indicate that thermal contraction cracking in the spruce forests has been infrequent throughout much of the last century. The proximity of wedge ice to the base of the aggrading permafrost table and the absence of old spruce roots spanning ice-wedge troughs suggest that ice-wedge cracking did occur in the forest environments during the cold and dry conditions associated with the Little Ice Age and early part of the 20th century. When these ice wedges cracked, minimum temperatures at the top of permafrost were probably at least 3–8 °C colder than presently observed and similar to present conditions at the tundra peatland.

Applying Transdisciplinary Research Strategies to Understanding and Eliminating Health Disparities

2006 ◽  
Vol 33 (4) ◽  
pp. 515-531 ◽  
Author(s):  
David B. Abrams
Keyword(s):  
Health Disparities ◽  
Health Education ◽  
Basic Science ◽  
Applied Research ◽  
Transdisciplinary Research ◽  
Evidence Based ◽  
Special Issue ◽  
Research Strategies ◽  
Social Inequities

This overview for the special issue of Health Education & Behavior on “Health Disparities and Social Inequities” briefly outlines the transdisciplinary (TD) approach to research and examines the scope of TD science. The need to embrace basic science as well as several domains of applied research is discussed along the TD “pipeline” from discovery to development to delivery to policy. The overview concludes with selected examples of the emerging TD science of disparities. One central challenge for a TD approach is the need to strengthen what is being called “the science of dissemination” along with improving the “dissemination of evidence-based science.”

Geomorphology of a thermo-erosion gully, Bylot Island, Nunavut, Canada1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Polar Continental Shelf Project Contribution 043-11.

2012 ◽  
Vol 49 (8) ◽  
pp. 979-986 ◽  
Author(s):  
Etienne Godin ◽  
Daniel Fortier
Keyword(s):  
Continental Shelf ◽  
Water Flow ◽  
Applied Research ◽  
Snow Accumulation ◽  
Main Channel ◽  
Ground Temperature ◽  
Special Issue ◽  
Bylot Island ◽  
Local Water ◽  
Length And Area

A thermo-erosion gully has been monitored in the valley of glacier C-79 on Bylot Island since 1999. The main channel of the gully reached 390 m in length a few months after its initiation and grew between 38 and 50 m/year over the following decade, for an overall approximated average of 75 m/year. In 2009, the total gully length and area, including the main and relict channels, were 2500 m and 25 000 m2, respectively. Gullies affect snow accumulation, and therefore ground temperature, local water flow, and drainage. Sinkholes, gully heads, pools, baydzherakhi, tunnels, and collapses were grouped as a function of time since gully formation in that area. Sinkholes and tunnels were formed every year after gully inception, and baydzherakhi were found in 3–10 year old sections of the gully. Stabilization of the gully floor and sides took about a decade.

The thermal regime of a retrogressive thaw slump near Mayo, Yukon Territory

2000 ◽  
Vol 37 (7) ◽  
pp. 967-981 ◽  
Author(s):  
C R Burn
Keyword(s):  
Dominant Mode ◽  
Yukon Territory ◽  
Permafrost Degradation ◽  
Near Surface ◽  
Ground Temperatures ◽  
Fine Grained ◽  
Data Loggers ◽  
Development Data ◽  
Retrogressive Thaw Slump ◽  
Frost Penetration

The development of a retrogressive thaw slump near Mayo, Yukon Territory, has been traced from initiation by bank erosion (~1949) of the Stewart River to stabilization in 1993-1994. The stabilized headwall of the slump is 450 m from the river, and the slope of the slump floor is 3°. A transect of the slump from the river to the stabilized headwall was drilled in July 1995, to determine the extent and rate of permafrost degradation in the slump floor. Thermistors were placed in access tubes to 12 m depth at five sites, four near the transect and one in undisturbed terrain, to determine the magnitude of thermal disturbance due to slump development. Data loggers at the sites recorded the ground temperature at 1 m depth for two years from August 1995. The annual mean ground temperatures measured by the data loggers varied between 1.2° and 1.8°C in the slump, compared with -2.4°C in undisturbed ground, indicating a disturbance of about 4°C due to slumping. The depth of thaw in the slump floor is consistent with the Stefan solution for thawing of permafrost. Conduction is the dominant mode of heat transfer in the slump, where the soil is fine grained and there is almost no organic horizon. Winter ground temperatures at 1 m depth were nearly 6°C warmer in the slump than in the surrounding forest, even though snow depths were similar, due to the release of latent heat during prolonged frost penetration. These data demonstrate the importance of subsurface conditions on near-surface ground temperatures in winter.

Sign in / Sign up

Export Citation Format

Share Document