scholarly journals Measurement Frequency Requirements For Permafrost Ground Temperature Monitoring: Analysis of Norman Wells Pipeline Data, Northwest Territories and Alberta

1989 ◽  
Author(s):  
M M Burgess ◽  
K W Riseborough
Keyword(s):  
Northwest Territories ◽  
Temperature Monitoring ◽  
Ground Temperature ◽  
Measurement Frequency ◽  
Permafrost Ground

Ground thermal contrasts and variability at an alpine pyramidal peak in central Austria (Innerer Knorrkogel, Venediger Mountains)

2021 ◽  
Author(s):  
Andreas Kellerer-Pirklbauer ◽  
Gerhard Karl Lieb
Keyword(s):  
Snow Cover ◽  
Thermal Regime ◽  
Ground Surface ◽  
Temperature Monitoring ◽  
Ground Temperature ◽  
Freeze Thaw ◽  
Ground Temperatures ◽  
Frost Weathering ◽  
Second Year ◽  
Ridge Flank

<p>Ground temperatures in alpine environments are severely influenced by slope orientation (aspect), slope inclination, local topoclimatic conditions, and thermal properties of the rock material. Small differences in one of these factors may substantially impact the ground thermal regime, weathering by freeze-thaw action or the occurrence of permafrost. To improve the understanding of differences, variations, and ranges of ground temperatures at single mountain summits, we studied the ground thermal conditions at a triangle-shaped (plan view), moderately steep pyramidal peak over a two-year period (2018-2020).</p><p>We installed 18 monitoring sites with 23 sensors near the summit of Innerer Knorrkogel (2882m asl), in summer 2018 with one- and multi-channel datalogger (Geoprecision). All three mountain ridges (east-, northwest-, and southwest-facing) and flanks (northeast-, west-, and south-facing) were instrumented with one-channel dataloggers at two different elevations (2840 and 2860m asl) at each ridge/flank to monitor ground surface temperatures. Three bedrock temperature monitoring sites with shallow boreholes (40cm) equipped with three sensors per site at each of the three mountain flanks (2870m asl) were established. Additionally, two ground surface temperature monitoring sites were installed at the summit.</p><p>Results show remarkable differences in mean annual ground temperatures (MAGT) between the 23 different sensors and the two years despite the small spatial extent (0.023 km²) and elevation differences (46m). Intersite variability at the entire mountain pyramid was 3.74°C in 2018/19 (mean MAGT: -0.40°C; minimum: -1.78°C; maximum: 1.96°C;) and 3.27°C in 2019/20 (mean MAGT: 0.08°C; minimum: -1.54°C; maximum: 1,73°C;). Minimum was in both years at the northeast-facing flank, maximum at the south-facing flank. In all but three sites, the second monitoring year was warmer than the first one (mean +0.48°C) related to atmospheric differences and site-specific snow conditions. The comparison of the MAGT-values of the two years (MAGT-2018/19 minus MAGT-2019/20) revealed large thermal inhomogeneities in the mountain summit ranging from +0.65° (2018/19 warmer than 2019/20) to -1.76°C (2018/19 colder than 2019/20) at identical sensors. Temperature ranges at the three different aspects but at equal elevations were 1.7-2.2°C at ridges and 1.8-3.7°C at flanks for single years. The higher temperature range for flank-sites is related to seasonal snow cover effects combined with higher radiation at sun-exposed sites. Although the ground temperature was substantially higher in the second year, the snow cover difference between the two years was variable. Some sites experienced longer snow cover periods in the second year 2019/20 (up to +85 days) whereas at other sites the opposite was observed (up to -85 days). Other frost weathering-related indicators (diurnal freeze-thaw cycles, frost-cracking window) show also large intersite and interannual differences.</p><p>Our study shows that the thermal regime at a triangle-shaped moderately steep pyramidal peak is very heterogeneous between different aspects and landforms (ridge/flank/summit) and between two monitoring years confirming earlier monitoring and modelling results. Due to high intersite and interannual variabilities, temperature-related processes such as frost-weathering can vary largely between neighbouring sites. Our study highlights the need for systematic and long-term ground temperature monitoring in alpine terrain to improve the understanding of small- to medium-scale temperature variabilities.</p>

scholarly journals Statistical modelling of ground temperature in mountain permafrost

2012 ◽  
Vol 468 (2141) ◽  
pp. 1472-1495 ◽  
Author(s):  
J. Blanchet ◽  
A. C. Davison
Keyword(s):  
Snow Cover ◽  
Air Temperature ◽  
Numerical Models ◽  
Statistical Modelling ◽  
Heat Propagation ◽  
Ground Temperature ◽  
Slope Instability ◽  
Swiss Alps ◽  
Permafrost Ground ◽  
Heat Transfers

Permafrost consists of soil and rocks that remain at 0 ° C or below for at least two consecutive years. In mountains, permafrost ground ice acts like cement, stabilizing rock walls. Its degradation, following climate warming, may lead to slope instability in high mountains and damage to infrastructure, so knowledge about its evolution is essential for risk analysis. In pure solids, heat is transferred by conduction, but permafrost ground is also subject to non-conductive fluxes, and heat transfers are influenced by factors such as air temperature and snow cover, so a deterministic scheme cannot fully describe heat propagation. Current approaches to modelling use numerical models involving heat conduction schemes and energy balance models, requiring data on quantities such as relative humidity and radiation. We describe a stochastic treatment of the heat equation, which adapts to space–time changes in heat transfers driven by factors such as air temperature and snow cover, without requiring corresponding data, as part of a statistical model. The flexibility and performance of our approach are illustrated using data from two boreholes in the Swiss Alps, which show the strong influence of snow cover on ground temperature and the long-term degradation of permafrost produced by the 2003 heat wave.

scholarly journals Challenges and solutions for long-term permafrost borehole temperature monitoring and data interpretation

2016 ◽  
Vol 71 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Rachel Luethi ◽  
Marcia Phillips
Keyword(s):  
Mechanical Strain ◽  
Data Interpretation ◽  
Temperature Monitoring ◽  
Ground Temperature ◽  
Temperature Changes ◽  
Ground Temperatures ◽  
Natural Processes ◽  
Construction Activity ◽  
Borehole Temperature

Abstract. Long-term borehole temperature monitoring in mountain permafrost environments is challenging under the hostile conditions reigning in alpine environments. On the basis of data measured in the SLF borehole network we show three situations where ground temperature data should be interpreted with caution. (i) Thermistors have the tendency to drift, particularly if exposed to moisture or mechanical strain. This induces apparent warming or cooling, which can be difficult to differentiate from real ground temperature changes. Recalibration of thermistor chains is impossible if they cannot be extracted as a result of borehole deformation in creeping permafrost terrain. A solution using zero-curtain-based detection of drift and correction of data is presented. This method is however limited to the active layer, due to the lack of a reference temperature at greater depth. (ii) In contrast to drift-induced apparent warming, actual warming may be induced by natural processes or by the effects of construction activity. (iii) Control data from neighbouring boreholes are sometimes used to fill data gaps and discern drift – however these data may only underline the strong spatial variability of ground temperatures rather than provide measurement redundancy. A selection of recently observed problems regarding borehole monitoring in a hostile measurement environment are discussed, and advantages and possible drawbacks of various solutions including measurement redundancy or alternate instrumentation are presented.

scholarly journals Automated Monitoring The Temperature Under Buildings With Pile Foundations In Salekhard (Preliminary Results)

2019 ◽  
Author(s):  
Ya. K. Kamnev ◽  
M. Yu. Filimonov ◽  
A. N. Shein ◽  
N. A. Vaganova
Keyword(s):  
Computer Modeling ◽  
Pile Foundation ◽  
Residential Buildings ◽  
Thermal Stabilization ◽  
Residential Building ◽  
Temperature Monitoring ◽  
Ground Temperature ◽  
Permafrost Zone ◽  
Temperature Fields ◽  
Thermal Conductivity Model

In the paper, we consider a method of ground temperature monitoring using the thermometric boreholes and computer modeling the residential buildings with the pile foundation in the city of Salekhard; note that it is located in the permafrost zone. Construction of the residential buildings and industrial structures in the permafrost zone and their operation is carried out according to the principle of preserving the frozen state of foundations. For ground temperature monitoring, thermometric boreholes are used. In a given time period, the measured temperatures are transferred to a server for further processing. Information about the temperature is an important factor for the safety of the buildings and it can be used to evaluate the piles bearing capacity. It allows to propose options for the soil thermal stabilization or to eliminate the detected technogenic heat sources. An approach of mathematical modeling to reconstruct the temperature fields in the pile foundation base of a building is discussed taking into account the data of temperature monitoring. 24 boreholes were equipped with more than 400 in-borehole thermal sensors for testing the method under the residential building I. The preliminary modeling is carried out for December and January 2020 for the contact thermal conductivity model with phase transition with the upper part of the geological section typical for Salekhard (the sandy soils). The modeling describes the freezing processes during the months in detail. The thermal monitoring allows to say that the ground in the base of the Residential building I is stable. But there are detected heat transfers near the borehole T1 at the depth of 12–14 m. The combination of monitoring and computer modeling makes it possible to assess the safety of the operation of the residential buildings in cities located in the permafrost zones.

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