scholarly journals Simulating Active Layer Thaw in a Boreal Environment

2007 ◽  
Vol 60 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Ming-ko Woo ◽  
Michael Mollinga ◽  
Sharon L. Smith
Keyword(s):  
Surface Temperature ◽  
Phase Change ◽  
Active Layer ◽  
Oil And Gas ◽  
Environmental Changes ◽  
Ground Surface ◽  
Ground Surface Temperature ◽  
Annual Variations ◽  
Discontinuous Permafrost ◽  
Boreal Environment

Abstract A large part of the boreal zone of the western Canadian Arctic is underlain by ice-rich discontinuous permafrost which when thawed, can lead to settlement of the ground surface that has implications for the integrity of northern infrastructure, including oil and gas pipelines. A simple yet physically-based model is desired to simulate thawing of the active layer in different materials commonly found along the Mackenzie Valley pipeline corridor. Stefan’s algorithm determines the phase change of soil moisture using ground surface temperature as the upper boundary condition and conduction to transfer heat to the freeze-thaw front. It is tested on a permafrost site near Wrigley, Northwest Territories, where the computed thaw penetration compares satisfactorily with field data. To further explore the effects of climate and soil types on active layer depth, three representative sites in the Mackenzie valley where ground surface temperatures are available were selected for simulation of ground thaw, under two summer conditions. Results of the simulation demonstrate the sensitivity of active layer thaw to (1) soil materials due to differential thermal properties, (2) moisture content, which largely controls the latent heat requirement for phase change, and (3) inter-annual variations in ground surface temperature. Given the strong potential for environmental changes in the vast boreal region, the model allows the active layer thaw responses to be easily assessed.

scholarly journals Climate trends in northern Ontario and Québec from borehole temperature profiles

2016 ◽  
Vol 12 (12) ◽  
pp. 2215-2227 ◽  
Author(s):  
Carolyne Pickler ◽  
Hugo Beltrami ◽  
Jean-Claude Mareschal
Keyword(s):  
Surface Temperature ◽  
Ground Surface ◽  
Ice Age ◽  
Climate Trends ◽  
James Bay ◽  
Northern Ontario ◽  
Ground Surface Temperature ◽  
Cooling Period ◽  
The Past ◽  
Discontinuous Permafrost

Abstract. The ground surface temperature histories of the past 500 years were reconstructed at 10 sites containing 18 boreholes in northeastern Canada. The boreholes, between 400 and 800 m deep, are located north of 51° N and west and east of James Bay in northern Ontario and Québec. We find that both sides of James Bay have experienced similar ground surface temperature histories with a warming of 1.51 ± 0.76 K during the period of 1850 to 2000, similar to borehole reconstructions for the southern portion of the Superior Province and in agreement with available proxy data. A cooling period corresponding to the Little Ice Age was found at only one site. Despite permafrost maps locating the sites in a region of discontinuous permafrost, the ground surface temperature histories suggest that the potential for permafrost was minimal to absent over the past 500 years. This could be the result of air surface temperature interpolation used in permafrost models being unsuitable to account for the spatial variability of ground temperatures along with an offset between ground and air surface temperatures due to the snow cover.

Effect of climate and moss vegetation on ground surface temperature and the active layer among different biogeographical regions in Antarctica

CATENA ◽  
2020 ◽  
Vol 190 ◽  
pp. 104562 ◽  
Author(s):  
Filip Hrbáček ◽  
Nicoletta Cannone ◽  
Michaela Kňažková ◽  
Francesco Malfasi ◽  
Peter Convey ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Active Layer ◽  
Ground Surface ◽  
Ground Surface Temperature ◽  
Biogeographical Regions

scholarly journals Spatio-Temporal Variations of Soil Active Layer Thickness in Chinese Boreal Forests from 2000 to 2015

2018 ◽  
Vol 10 (8) ◽  
pp. 1225 ◽  
Author(s):  
Xiongxiong Bai ◽  
Jian Yang ◽  
Bo Tao ◽  
Wei Ren
Keyword(s):  
Surface Temperature ◽  
Layer Thickness ◽  
Active Layer ◽  
Air Temperature ◽  
Climate Warming ◽  
Boreal Forests ◽  
Ground Surface ◽  
Active Layer Thickness ◽  
Ground Surface Temperature ◽  
Spatio Temporal

The soil active layer in boreal forests is sensitive to climate warming. Climate-induced changes in the active layer may greatly affect the global carbon budget and planetary climatic system by releasing large quantities of greenhouse gases that currently are stored in permafrost. Ground surface temperature is an immediate driver of active layer thickness (ALT) dynamics. In this study, we mapped ALT distribution in Chinese boreal larch forests from 2000 to 2015 by integrating remote sensing data with the Stefan equation. We then examined the changes of the ALT in response to changes in ground surface temperature and identified drivers of the spatio-temporal patterns of ALT. Active layer thickness varied from 1.18 to 1.3 m in the study area. Areas of nonforested land and low elevation or with increased air temperature had a relatively high ALT, whereas ALT was lower at relatively high elevation and with decreased air temperatures. Interannual variations of ALT had no obvious trend, however, and the ALT changed at a rate of only −0.01 and 0.01 m year−1. In a mega-fire patch of 79,000 ha burned in 2003, ΔALT (ALTi − ALT2002, where 2003 ≤ i ≤ 2015) was significantly higher than in the unburned area, with the influence of the wildfire persisting 10 years. Under the high emission scenario (RCP8.5), an increase of 2.6–4.8 °C in mean air temperature would increase ALT into 1.46–1.55 m by 2100, which in turn would produce a significant positive feedback to climate warming.

scholarly journals Climate trends in northern Ontario and Quebec from borehole temperature profiles

2016 ◽  
Author(s):  
C. Pickler ◽  
H. Beltrami ◽  
J.-C. Mareschal
Keyword(s):  
Surface Temperature ◽  
Ground Surface ◽  
Ice Age ◽  
Climate Trends ◽  
James Bay ◽  
Northern Ontario ◽  
Ground Surface Temperature ◽  
Cooling Period ◽  
The Past ◽  
Discontinuous Permafrost

Abstract. The ground surface temperature histories of the past 500 years were reconstructed at 10 sites containing 18 boreholes in northeastern Canada. The boreholes, between 400 and 800 m deep, are located north of 51° N, and west and east of James Bay in northern Ontario and Quebec. We find that both sides of James Bay have experienced similar ground surface temperature histories with a warming of ~ 1–2 K for the last 150 years, similar to borehole reconstructions for the southern portion of the Superior Province and in agreement with available proxy data. A cooling period corresponding to the little ice age was found at only one site. Despite permafrost maps locating the sites in a region of discontinuous permafrost, the ground surface temperature histories suggest that the entire region is and was free of permafrost for the past 500 years. This could be the result of air surface temperature interpolation used in permafrost models being unsuitable to represent the spatial variability of ground temperatures along with an offset between ground and air surface temperatures due to the snow cover.

scholarly journals Modeling the Temperature Field in the Ground with an Installed Slinky-Coil Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4010
Author(s):  
Monika Gwadera ◽  
Krzysztof Kupiec
Keyword(s):  
Temperature Field ◽  
Heat Exchanger ◽  
Surface Temperature ◽  
Ground Surface ◽  
Heat Sources ◽  
Ground Surface Temperature ◽  
Coil Heat Exchanger ◽  
The Relationship ◽  
Temperature Responses ◽  
Coil Heat

In order to find the temperature field in the ground with a heat exchanger, it is necessary to determine temperature responses of the ground caused by heat sources and the influence of the environment. To determine the latter, a new model of heat transfer in the ground under natural conditions was developed. The heat flux of the evaporation of moisture from the ground was described by the relationship taking into account the annual amount of rainfall. The analytical solution for the equations of this model is presented. Under the conditions for which the calculations were performed, the following data were obtained: the average ground surface temperature Tsm = 10.67 °C, the ground surface temperature amplitude As = 13.88 K, and the phase angle Ps = 0.202 rad. This method makes it possible to easily determine the undisturbed ground temperature at any depth and at any time. This solution was used to find the temperature field in the ground with an installed slinky-coil heat exchanger that consisted of 63 coils. The results of calculations according to the presented model were compared with the results of measurements from the literature. The 3D model for the ground with an installed heat exchanger enables the analysis of the influence of miscellaneous parameters of the process of extracting or supplying heat from/to the ground on its temperature field.

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