M. Majdański, W. Dobiński, A. Marciniak, B. Owoc, M. Glazer, M. Osuch, T. Wawrzyniak
Two seismic field surveys were organized in the Fuglebekken coastal catchment of Hornsund, Spitsbergen, Svalbard, to map frozen and unfrozen ground and assess the spatial and temporal state of the permafrost. Surveys were conducted during maximum thawing in September and maximum freezing in April of the following year. The obtained seismic wavefields were interpreted using three methods: the dispersion of surface waves, seismic refraction, and travel time tomography. The seismic experiments were supported by nearby boreholes with continuous thermal monitoring. In the frozen survey, a gradual increase in ice content of water‐filled sediments was found, farther from the coast. In September the shallow sensors in the boreholes validated positive ground temperatures down to 3.0 m depth, with below‐zero temperatures at greater depths. However, seismic tomography indicated that the ground was unfrozen down to 30 m. The ground probably remained unfrozen due to intrusion of high‐salinity seawater, even though it had been below 0°C. In April, in the area 300 m and farther from the coast, the ground below 3 m depth was frozen, except for a 19‐m‐deep open talik identified in a borehole at the slope of Fugle Mountain. We attribute the complex spatial extent, form, and condition of permafrost in the Fuglebekken coastal catchment to multiple factors, including variable solar energy, snow and ground cover, thermal and humidity properties of the soil, subsurface water flow, and seawater intrusion. The presented combination of seismic methods provides a new robust and precise approach to assess the spatial variability of permafrost in a coastal environment. The proposed interpretation shows deep percolation of subsurface flow into permafrost and its seasonal unfreezing at a depth of 30 m in both the zone of saltwater intrusion and the slope area.
{"title":"Variations of permafrost under freezing and thawing conditions in the coastal catchment Fuglebekken (Hornsund, Spitsbergen, Svalbard)","authors":"M. Majdański, W. Dobiński, A. Marciniak, B. Owoc, M. Glazer, M. Osuch, T. Wawrzyniak","doi":"10.1002/ppp.2147","DOIUrl":"https://doi.org/10.1002/ppp.2147","url":null,"abstract":"Two seismic field surveys were organized in the Fuglebekken coastal catchment of Hornsund, Spitsbergen, Svalbard, to map frozen and unfrozen ground and assess the spatial and temporal state of the permafrost. Surveys were conducted during maximum thawing in September and maximum freezing in April of the following year. The obtained seismic wavefields were interpreted using three methods: the dispersion of surface waves, seismic refraction, and travel time tomography. The seismic experiments were supported by nearby boreholes with continuous thermal monitoring. In the frozen survey, a gradual increase in ice content of water‐filled sediments was found, farther from the coast. In September the shallow sensors in the boreholes validated positive ground temperatures down to 3.0 m depth, with below‐zero temperatures at greater depths. However, seismic tomography indicated that the ground was unfrozen down to 30 m. The ground probably remained unfrozen due to intrusion of high‐salinity seawater, even though it had been below 0°C. In April, in the area 300 m and farther from the coast, the ground below 3 m depth was frozen, except for a 19‐m‐deep open talik identified in a borehole at the slope of Fugle Mountain. We attribute the complex spatial extent, form, and condition of permafrost in the Fuglebekken coastal catchment to multiple factors, including variable solar energy, snow and ground cover, thermal and humidity properties of the soil, subsurface water flow, and seawater intrusion. The presented combination of seismic methods provides a new robust and precise approach to assess the spatial variability of permafrost in a coastal environment. The proposed interpretation shows deep percolation of subsurface flow into permafrost and its seasonal unfreezing at a depth of 30 m in both the zone of saltwater intrusion and the slope area.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"264 - 276"},"PeriodicalIF":5.0,"publicationDate":"2022-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47158214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yan-hui You, Qihao Yu, Xinbin Wang, Lei Guo, Kun Chen, Qingbai Wu
The thermal effects of cast‐in‐place piles on the surrounding permafrost frequently induce deformation or failure of piles in permafrost regions. Because piles are directly inserted into the permafrost layer, the thermal disturbance of the piles is more straightforward than that of road embankments to the permafrost. Thermosyphons have proven to be effective in stabilizing the embankments of highways and railways in permafrost regions. However, the effects of thermosyphons on the thermal regime and stability of the cast‐in‐place piles remain unclear. The foundation soils of most piles in permafrost regions along the Qinghai‐Tibet Power Transmission Line were cooled by thermosyphons, and the results of a 7‐year‐period monitoring of ground temperature and deformation of a pile are presented in this paper. The results showed that the extent of thawed permafrost during the installation of the pile extended more than 5 m away from the pile. Thermosyphons shortened the refreezing time by more than 2 months. Thermosyphons cooled the surrounding permafrost to temperatures below the ambient ground temperature at the end of the cold seasons, and the temperature difference lasted until the end of the warm seasons owing to cold reserves formed in the cold season. The thermosyphons mitigated the thermal effects of the concrete pile owing to their higher thermal conductivity. Thermosyphons also significantly decreased the rate of active layer thickening around the pile compared to that observed in a natural field under a warming climate. Generally, thermosyphons stabilized the piles during the observation period by cooling the permafrost around the pile and producing a greater adfreeze force to counteract the frost heave force and subsequently support the tower. Additional thermosyphons or insulation measures may be necessary to ensure the long‐term stability of piles, considering a faster degradation of the ambient permafrost than expected. The results may provide insights into the design and maintenance of cast‐in‐place piles in warm permafrost regions.
{"title":"Effects of thermosyphons on the thermal regime and stability of cast‐in‐place piles in permafrost regions on the Qinghai‐Tibet Plateau","authors":"Yan-hui You, Qihao Yu, Xinbin Wang, Lei Guo, Kun Chen, Qingbai Wu","doi":"10.1002/ppp.2144","DOIUrl":"https://doi.org/10.1002/ppp.2144","url":null,"abstract":"The thermal effects of cast‐in‐place piles on the surrounding permafrost frequently induce deformation or failure of piles in permafrost regions. Because piles are directly inserted into the permafrost layer, the thermal disturbance of the piles is more straightforward than that of road embankments to the permafrost. Thermosyphons have proven to be effective in stabilizing the embankments of highways and railways in permafrost regions. However, the effects of thermosyphons on the thermal regime and stability of the cast‐in‐place piles remain unclear. The foundation soils of most piles in permafrost regions along the Qinghai‐Tibet Power Transmission Line were cooled by thermosyphons, and the results of a 7‐year‐period monitoring of ground temperature and deformation of a pile are presented in this paper. The results showed that the extent of thawed permafrost during the installation of the pile extended more than 5 m away from the pile. Thermosyphons shortened the refreezing time by more than 2 months. Thermosyphons cooled the surrounding permafrost to temperatures below the ambient ground temperature at the end of the cold seasons, and the temperature difference lasted until the end of the warm seasons owing to cold reserves formed in the cold season. The thermosyphons mitigated the thermal effects of the concrete pile owing to their higher thermal conductivity. Thermosyphons also significantly decreased the rate of active layer thickening around the pile compared to that observed in a natural field under a warming climate. Generally, thermosyphons stabilized the piles during the observation period by cooling the permafrost around the pile and producing a greater adfreeze force to counteract the frost heave force and subsequently support the tower. Additional thermosyphons or insulation measures may be necessary to ensure the long‐term stability of piles, considering a faster degradation of the ambient permafrost than expected. The results may provide insights into the design and maintenance of cast‐in‐place piles in warm permafrost regions.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"277 - 285"},"PeriodicalIF":5.0,"publicationDate":"2022-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42234143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ice‐wedge polygon troughs play an important role in controlling the hydrology of low‐relief polygonal tundra regions. Lateral surface flow is confined to troughs only, but it is often neglected in model projections of permafrost thermal hydrology. Recent field and modeling studies have shown that, after rain events, increases in trough water levels are significantly more than the observed precipitation, highlighting the role of lateral surface flow in the polygonal tundra. Therefore, understanding how trough lateral surface flow can influence polygonal tundra thermal hydrology is important, especially under projected changes in temperatures and rainfall in the Arctic regions. Using an integrated cryohydrology model, this study presents plot‐scale end‐of‐century projections of ice‐wedge polygon water budget components and active layer thickness with and without trough lateral surface flow under the Representative Concentration Pathway 8.5 scenario. Trough lateral surface flow is incorporated through a newly developed empirical model, evaluated against field measurements. The numerical scenario that includes trough lateral surface flow simulates discharge (outflow from a polygon) and recharge (rain‐induced inflow to a polygon trough from upslope areas), while the scenario that does not include trough lateral surface flow ignores recharge. The results show considerable reduction (about 100–150%) in evapotranspiration and discharge in rainy years in the scenarios ignoring trough lateral surface flow, but less effect on soil water storage, in comparison with the scenario with trough lateral surface flow. In addition, the results demonstrate long‐term changes (~10–15 cm increase) in active layer thickness when trough lateral surface flow is modeled. This study highlights the importance of including lateral surface flow processes to better understand the long‐term thermal and hydrological changes in low‐relief polygonal tundra regions under a changing climate.
{"title":"Modeling the role of lateral surface flow in low‐relief polygonal tundra","authors":"A. Jan","doi":"10.1002/ppp.2145","DOIUrl":"https://doi.org/10.1002/ppp.2145","url":null,"abstract":"Ice‐wedge polygon troughs play an important role in controlling the hydrology of low‐relief polygonal tundra regions. Lateral surface flow is confined to troughs only, but it is often neglected in model projections of permafrost thermal hydrology. Recent field and modeling studies have shown that, after rain events, increases in trough water levels are significantly more than the observed precipitation, highlighting the role of lateral surface flow in the polygonal tundra. Therefore, understanding how trough lateral surface flow can influence polygonal tundra thermal hydrology is important, especially under projected changes in temperatures and rainfall in the Arctic regions. Using an integrated cryohydrology model, this study presents plot‐scale end‐of‐century projections of ice‐wedge polygon water budget components and active layer thickness with and without trough lateral surface flow under the Representative Concentration Pathway 8.5 scenario. Trough lateral surface flow is incorporated through a newly developed empirical model, evaluated against field measurements. The numerical scenario that includes trough lateral surface flow simulates discharge (outflow from a polygon) and recharge (rain‐induced inflow to a polygon trough from upslope areas), while the scenario that does not include trough lateral surface flow ignores recharge. The results show considerable reduction (about 100–150%) in evapotranspiration and discharge in rainy years in the scenarios ignoring trough lateral surface flow, but less effect on soil water storage, in comparison with the scenario with trough lateral surface flow. In addition, the results demonstrate long‐term changes (~10–15 cm increase) in active layer thickness when trough lateral surface flow is modeled. This study highlights the importance of including lateral surface flow processes to better understand the long‐term thermal and hydrological changes in low‐relief polygonal tundra regions under a changing climate.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"214 - 225"},"PeriodicalIF":5.0,"publicationDate":"2022-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46605915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rock glaciers (RGs) are landscape features impacting the composition and magnitude of runoff and, given their ice content, they are used as indicators for past and present climate conditions. While our knowledge of RG coverage has improved over recent years in many mountainous regions, there is very little information available for RGs in Greenland. Here, we provide evidence for an active RG in West Greenland, about 230 km south of what previously has been identified as the southern limit of active RGs. We present field evidence such as bottom temperature of the snow pack and surface displacements and indicate how these results could be utilized in further studies to better assess RG distribution or their ice content.
{"title":"Challenging the southern boundary of active rock glaciers in West Greenland","authors":"J. Abermann, K. Langley","doi":"10.1002/ppp.2139","DOIUrl":"https://doi.org/10.1002/ppp.2139","url":null,"abstract":"Rock glaciers (RGs) are landscape features impacting the composition and magnitude of runoff and, given their ice content, they are used as indicators for past and present climate conditions. While our knowledge of RG coverage has improved over recent years in many mountainous regions, there is very little information available for RGs in Greenland. Here, we provide evidence for an active RG in West Greenland, about 230 km south of what previously has been identified as the southern limit of active RGs. We present field evidence such as bottom temperature of the snow pack and surface displacements and indicate how these results could be utilized in further studies to better assess RG distribution or their ice content.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"129 - 133"},"PeriodicalIF":5.0,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49026863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the mechanical properties of frozen flawed rock masses is fundamental to conducting safe rock engineering in frozen rock strata. However, there has been scarce research in this area, especially on key issues such as the strength and deformability of frozen flawed rock masses and failure processes under load. In this paper, frozen flawed sandstone was subjected to uniaxial compression and the cracking process was observed. The influences of flaw inclination angle and freezing temperature on the strength and cracking behavior of frozen flawed sandstone under load were determined. The results show that: (a) the strength of frozen flawed sandstone increases with increases in flaw inclination and decreases in temperature; (b) the flaw inclination has a dramatic influence on both the crack coalescence behavior and the final failure form of frozen flawed samples under compression; and (c) the significant influence of freezing temperature on the cracking behavior of frozen flawed sandstone is caused by the interaction between flaw ice and its surrounding rock. Strengthening of flawed sandstone by freezing results because (i) pore ice provides support and cohesion at the pore scale, while (ii) at the crack scale ice can support the flaw and resist its deformation during compression, and cementation of the ice–rock interface provides normal and tangential cracking resistance.
{"title":"Strength and the cracking behavior of frozen sandstone containing ice‐filled flaws under uniaxial compression","authors":"H. Jia, L. Han, T. Zhao, Q. Sun, Xian-jun Tan","doi":"10.1002/ppp.2142","DOIUrl":"https://doi.org/10.1002/ppp.2142","url":null,"abstract":"Understanding the mechanical properties of frozen flawed rock masses is fundamental to conducting safe rock engineering in frozen rock strata. However, there has been scarce research in this area, especially on key issues such as the strength and deformability of frozen flawed rock masses and failure processes under load. In this paper, frozen flawed sandstone was subjected to uniaxial compression and the cracking process was observed. The influences of flaw inclination angle and freezing temperature on the strength and cracking behavior of frozen flawed sandstone under load were determined. The results show that: (a) the strength of frozen flawed sandstone increases with increases in flaw inclination and decreases in temperature; (b) the flaw inclination has a dramatic influence on both the crack coalescence behavior and the final failure form of frozen flawed samples under compression; and (c) the significant influence of freezing temperature on the cracking behavior of frozen flawed sandstone is caused by the interaction between flaw ice and its surrounding rock. Strengthening of flawed sandstone by freezing results because (i) pore ice provides support and cohesion at the pore scale, while (ii) at the crack scale ice can support the flaw and resist its deformation during compression, and cementation of the ice–rock interface provides normal and tangential cracking resistance.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"160 - 175"},"PeriodicalIF":5.0,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42165868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruiqing Shi, Z. Wen, Desheng Li, Qiang Gao, Yanjing Wei
Owing to a minor thermal disturbance to the permafrost environment, cast‐in‐place piles are widely used for building and bridge foundations in permafrost regions. However, because of the dynamic and cyclic variation in frozen ground affected by the atmosphere, the load transfer mechanism is not yet clear, and the current design is economically insufficient. To illustrate the bearing pattern of cast‐in‐place piles subjected to freeze–thaw cycles, a systematic in situ investigation was carried out. Results show that the load from the superstructure has a marginal action effect, while freeze–thaw cycles have a more significant action effect. Freeze–thaw cycles have a decisive effect on the dynamic variations of the pile's working state and action effect sharing while the mechanisms are quite different, which vary with depths. Action effect sharing of the pile shaft and tip experiences a cyclic variation and is affected by the long‐term effect of freeze–thaw cycles. The shaft takes an increasing sharing proportion gradually and has a 19% rise after two freeze–thaw cycles, while the pile tip goes the opposite way. Two years after the building is completed, the bearing capacity is almost entirely provided by shaft resistance and mainly by the upper one‐third of the pile. This research clarifies several essential issues about the bearing pattern and provides solid scientific support and novel opinions for the pile design in permafrost regions.
{"title":"Effect of freeze–thaw cycles on the performance of cast‐in‐place piles in permafrost regions: Working state and action effect sharing","authors":"Ruiqing Shi, Z. Wen, Desheng Li, Qiang Gao, Yanjing Wei","doi":"10.1002/ppp.2140","DOIUrl":"https://doi.org/10.1002/ppp.2140","url":null,"abstract":"Owing to a minor thermal disturbance to the permafrost environment, cast‐in‐place piles are widely used for building and bridge foundations in permafrost regions. However, because of the dynamic and cyclic variation in frozen ground affected by the atmosphere, the load transfer mechanism is not yet clear, and the current design is economically insufficient. To illustrate the bearing pattern of cast‐in‐place piles subjected to freeze–thaw cycles, a systematic in situ investigation was carried out. Results show that the load from the superstructure has a marginal action effect, while freeze–thaw cycles have a more significant action effect. Freeze–thaw cycles have a decisive effect on the dynamic variations of the pile's working state and action effect sharing while the mechanisms are quite different, which vary with depths. Action effect sharing of the pile shaft and tip experiences a cyclic variation and is affected by the long‐term effect of freeze–thaw cycles. The shaft takes an increasing sharing proportion gradually and has a 19% rise after two freeze–thaw cycles, while the pile tip goes the opposite way. Two years after the building is completed, the bearing capacity is almost entirely provided by shaft resistance and mainly by the upper one‐third of the pile. This research clarifies several essential issues about the bearing pattern and provides solid scientific support and novel opinions for the pile design in permafrost regions.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"147 - 159"},"PeriodicalIF":5.0,"publicationDate":"2022-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47034438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ya. V. Tikhonravova, E. Slagoda, V. Butakov, E. Koroleva, G. Simonova, R. Sysolyatin
Heterogeneous ice wedges were studied within the peatland of the drained lake on the Pur‐Taz interfluve (67°20′14.8″, 078°55′47.1″, Northwest Siberia). The elements of the ice‐wedge structure were identified: young ice wedge, shoulders, selvages, closed‐cavity ices, and ice lenses in a peatland. Different genetic types of ice (ice vein, congelation ice, and segregated ice) were revealed by analyzing the elements of the ice‐wedge structure under polarized light and analyzing their chemical compositions. Genetic types of the ice indicate the different mechanisms of ice‐wedge formation. The ice vein forms due to fast bilateral freezing of primarily meltwater in a thermal contraction crack. The congelation ice forms due to the slow freezing of free water that has accumulated into a thermokarst cavity. The segregated ice forms due to pore water migration to the freezing zone. The elements of the ice‐wedge structure have variable stable isotope values (δ18O from −13.5‰ to −21.9‰ and δD from −87.7‰ to −154.6‰). The high range of deuterium excess values (13.8‰ to 32‰) indicates fractionation at condensation. The mean winter paleotemperature calculated using Vasil’chuk’s equations for the ice‐wedge pats formed by the ice veins varied in the range of −18 to −22°C, which is not very different from current values and is consistent with the isotopic data of ice wedges from nearby regions of Northwest Siberia. The paleotemperature average error can equal 4.5°C if we ignore the data on the ice petrographic analysis. The error depends on where and how the ice wedges are sampled, because of varying genetic types within the ground ice. This could lead to different palaeoclimatological interpretations.
{"title":"Isotopic composition of heterogeneous ice wedges in peatlands of the Pur‐Taz interfluve (northern West Siberia)","authors":"Ya. V. Tikhonravova, E. Slagoda, V. Butakov, E. Koroleva, G. Simonova, R. Sysolyatin","doi":"10.1002/ppp.2138","DOIUrl":"https://doi.org/10.1002/ppp.2138","url":null,"abstract":"Heterogeneous ice wedges were studied within the peatland of the drained lake on the Pur‐Taz interfluve (67°20′14.8″, 078°55′47.1″, Northwest Siberia). The elements of the ice‐wedge structure were identified: young ice wedge, shoulders, selvages, closed‐cavity ices, and ice lenses in a peatland. Different genetic types of ice (ice vein, congelation ice, and segregated ice) were revealed by analyzing the elements of the ice‐wedge structure under polarized light and analyzing their chemical compositions. Genetic types of the ice indicate the different mechanisms of ice‐wedge formation. The ice vein forms due to fast bilateral freezing of primarily meltwater in a thermal contraction crack. The congelation ice forms due to the slow freezing of free water that has accumulated into a thermokarst cavity. The segregated ice forms due to pore water migration to the freezing zone. The elements of the ice‐wedge structure have variable stable isotope values (δ18O from −13.5‰ to −21.9‰ and δD from −87.7‰ to −154.6‰). The high range of deuterium excess values (13.8‰ to 32‰) indicates fractionation at condensation. The mean winter paleotemperature calculated using Vasil’chuk’s equations for the ice‐wedge pats formed by the ice veins varied in the range of −18 to −22°C, which is not very different from current values and is consistent with the isotopic data of ice wedges from nearby regions of Northwest Siberia. The paleotemperature average error can equal 4.5°C if we ignore the data on the ice petrographic analysis. The error depends on where and how the ice wedges are sampled, because of varying genetic types within the ground ice. This could lead to different palaeoclimatological interpretations.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"114 - 128"},"PeriodicalIF":5.0,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43197573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Costard, E. Gautier, P. Konstantinov, F. Bouchard, A. Séjourné, L. Dupeyrat, A. Fedorov
Recent evidence has shown that Arctic regions have warmed about twice as much as elsewhere on the planet over the last few decades, and that high‐latitude permafrost–periglacial processes and hydrological systems are notably responsive to rising temperatures. The aim of this paper is to report on the thermal regime of islands located along the Lena River floodplain, upstream of the city of Yakutsk (eastern Siberia). Four islands were monitored using waterproof dataloggers and continuous monitoring of frozen soil in contact with ice breakup of the Lena River. For each of these islands, we measured: (a) ground surface temperature, air and frozen soil temperatures at different depths; and (b) submersion duration during the flood. Our results show that within a zone of thick and continuous permafrost, the Lena floodplain is notably heterogeneous, with a combination of permanently and seasonally frozen islands. The ice breakups seem to have a negligible impact on the ground thermal regime. Our study confirms that relatively young (<30 years old) islands, composed of fine sand material, appear less prone to permafrost formation compared to older islands with ice‐rich silty material.
{"title":"Thermal regime variability of islands in the Lena River near Yakutsk, eastern Siberia","authors":"F. Costard, E. Gautier, P. Konstantinov, F. Bouchard, A. Séjourné, L. Dupeyrat, A. Fedorov","doi":"10.1002/ppp.2136","DOIUrl":"https://doi.org/10.1002/ppp.2136","url":null,"abstract":"Recent evidence has shown that Arctic regions have warmed about twice as much as elsewhere on the planet over the last few decades, and that high‐latitude permafrost–periglacial processes and hydrological systems are notably responsive to rising temperatures. The aim of this paper is to report on the thermal regime of islands located along the Lena River floodplain, upstream of the city of Yakutsk (eastern Siberia). Four islands were monitored using waterproof dataloggers and continuous monitoring of frozen soil in contact with ice breakup of the Lena River. For each of these islands, we measured: (a) ground surface temperature, air and frozen soil temperatures at different depths; and (b) submersion duration during the flood. Our results show that within a zone of thick and continuous permafrost, the Lena floodplain is notably heterogeneous, with a combination of permanently and seasonally frozen islands. The ice breakups seem to have a negligible impact on the ground thermal regime. Our study confirms that relatively young (<30 years old) islands, composed of fine sand material, appear less prone to permafrost formation compared to older islands with ice‐rich silty material.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"18 - 31"},"PeriodicalIF":5.0,"publicationDate":"2022-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42222828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study of Pleistocene polygons in Europe carried out using the collection of satellite images available in Google Earth™ provides new data on the distribution of ground cracking by thermal contraction during glacial periods and sheds light on some factors controlling their formation. The distribution map shows that thermal contraction cracking affected terrain between latitude 43.5°N and the southern limit of the Fennoscandian Ice Sheet at 15 ka, with a concentration of polygons north of latitude 51°N. A clear asymmetry exists in relation to longitude, with a greater southward extension of polygons in France (43.5°N) than in central Europe (47°N). Analysis of the characteristics of polygons at the European scale reveals an association with lithology, latitude, and the age of the sediments in which they formed. The morphological evolution over time reconstructed from observations of polygons of contrasting ages indicates that a stable mature phase, characterized by small (mean size 15 m), regular polygons with numerous Y‐junctions, is reached after ca. 4 ka of thermal contraction cracking activity.
{"title":"Distribution and characteristics of Pleistocene ground thermal contraction polygons in Europe from satellite images","authors":"P. Bertran","doi":"10.1002/ppp.2137","DOIUrl":"https://doi.org/10.1002/ppp.2137","url":null,"abstract":"The study of Pleistocene polygons in Europe carried out using the collection of satellite images available in Google Earth™ provides new data on the distribution of ground cracking by thermal contraction during glacial periods and sheds light on some factors controlling their formation. The distribution map shows that thermal contraction cracking affected terrain between latitude 43.5°N and the southern limit of the Fennoscandian Ice Sheet at 15 ka, with a concentration of polygons north of latitude 51°N. A clear asymmetry exists in relation to longitude, with a greater southward extension of polygons in France (43.5°N) than in central Europe (47°N). Analysis of the characteristics of polygons at the European scale reveals an association with lithology, latitude, and the age of the sediments in which they formed. The morphological evolution over time reconstructed from observations of polygons of contrasting ages indicates that a stable mature phase, characterized by small (mean size 15 m), regular polygons with numerous Y‐junctions, is reached after ca. 4 ka of thermal contraction cracking activity.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"33 1","pages":"113 - 99"},"PeriodicalIF":5.0,"publicationDate":"2022-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43855525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Issue Information","authors":"","doi":"10.1002/ppp.2118","DOIUrl":"https://doi.org/10.1002/ppp.2118","url":null,"abstract":"No abstract is available for this article.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":" ","pages":""},"PeriodicalIF":5.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47221504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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