Ice wedges are considered as a paleoarchive of winter air temperatures as their stable isotope composition has been widely used to reconstruct winter climatic conditions in the Arctic regions. Ice wedge stable isotope records, obtained in recent decades for many Arctic permafrost areas of Russia and North America, demonstrate a clear shift from lower to higher values between the Late Pleistocene and Holocene (by 5–10‰ for δ18O values in some regions of the Russian Arctic), which is widely accepted as evidence of winter air temperature increase. However, the evolution of winter air temperatures during the Holocene is less clear and, according to proxy reconstructions, winter climate trends are not synchronous and may significantly vary throughout the Arctic. In this study, we investigate the stable isotope composition of Holocene syngenetic ice wedges and modern ice veinlets of northwestern Siberia. Radiocarbon dating of enclosing sediments and a few dates of organic material from ice wedges demonstrate that ice wedges grew constantly within the study area during the Holocene though early–mid‐Holocene in northwestern Siberia is often considered as a thermal optimum. In fact, many proxy records indicate an increase of summer air temperatures followed by thermokarst activity, peatland formation, and northward advance of the treeline. According to our data, winter climate conditions in terms of mean air temperature of the coldest winter month (January) did not change significantly during the key Holocene stages, and during the Greenlandian and most of the Northgrippian stages (between 11.4 and 6 cal ka BP) mean January air temperature (TmJ) varied between −21 and −30°C, and from the end of the Northgrippian, during the Meghalayan stages of Holocene (5.2–0.9 cal ka BP), TmJ varied between −24 to −28°C. Mean January air temperature during the Holocene was generally 1–2°C lower than the modern one, meanwhile the submeridional direction of TmJ isotherms and eastward decrease of TmJ values in Holocene are similar to the modern pattern.
冰楔被认为是冬季气温的古档案，其稳定的同位素组成已被广泛用于重建北极地区的冬季气候条件。近几十年来在俄罗斯和北美许多北极多年冻土区获得的冰楔稳定同位素记录表明，在晚更新世和全新世之间，δ18O值明显由低向高转变(俄罗斯北极一些地区δ18O值变化了5-10‰)，这被广泛认为是冬季气温升高的证据。然而，全新世冬季气温的演变不太清楚，根据代理重建，冬季气候趋势不是同步的，可能在整个北极地区发生显著变化。本文研究了西伯利亚西北部全新世同生冰楔和现代冰脉的稳定同位素组成。外围沉积物的放射性碳定年和一些冰楔有机物的定年表明，在全新世期间，研究区内的冰楔不断生长，尽管西伯利亚西北部早-中全新世通常被认为是热最佳时期。事实上，许多替代记录表明夏季气温升高，随后是热岩溶活动、泥炭地形成和树线向北推进。研究结果表明，全新世关键时期冬季最冷月份(1月)平均气温变化不显著，格陵兰期和北格里平期(11.4 ~ 6 cal ka BP) 1月平均气温(TmJ)在- 21 ~ - 30°C之间变化，北格里平期结束后，全新世梅加拉亚期(5.2 ~ 0.9 cal ka BP) 1月平均气温(TmJ)在- 24 ~ - 28°C之间变化。全新世1月平均气温普遍比现代低1 ~ 2℃，同时，全新世TmJ等温线的下沉方向和TmJ值的东降趋势与现代相似。
{"title":"Holocene January paleotemperature of northwestern Siberia reconstructed based on stable isotope ratio of ice wedges","authors":"Y. Vasil'chuk, A. Vasil'chuk, N. Budantseva","doi":"10.1002/ppp.2177","DOIUrl":"https://doi.org/10.1002/ppp.2177","url":null,"abstract":"Ice wedges are considered as a paleoarchive of winter air temperatures as their stable isotope composition has been widely used to reconstruct winter climatic conditions in the Arctic regions. Ice wedge stable isotope records, obtained in recent decades for many Arctic permafrost areas of Russia and North America, demonstrate a clear shift from lower to higher values between the Late Pleistocene and Holocene (by 5–10‰ for δ18O values in some regions of the Russian Arctic), which is widely accepted as evidence of winter air temperature increase. However, the evolution of winter air temperatures during the Holocene is less clear and, according to proxy reconstructions, winter climate trends are not synchronous and may significantly vary throughout the Arctic. In this study, we investigate the stable isotope composition of Holocene syngenetic ice wedges and modern ice veinlets of northwestern Siberia. Radiocarbon dating of enclosing sediments and a few dates of organic material from ice wedges demonstrate that ice wedges grew constantly within the study area during the Holocene though early–mid‐Holocene in northwestern Siberia is often considered as a thermal optimum. In fact, many proxy records indicate an increase of summer air temperatures followed by thermokarst activity, peatland formation, and northward advance of the treeline. According to our data, winter climate conditions in terms of mean air temperature of the coldest winter month (January) did not change significantly during the key Holocene stages, and during the Greenlandian and most of the Northgrippian stages (between 11.4 and 6 cal ka BP) mean January air temperature (TmJ) varied between −21 and −30°C, and from the end of the Northgrippian, during the Meghalayan stages of Holocene (5.2–0.9 cal ka BP), TmJ varied between −24 to −28°C. Mean January air temperature during the Holocene was generally 1–2°C lower than the modern one, meanwhile the submeridional direction of TmJ isotherms and eastward decrease of TmJ values in Holocene are similar to the modern pattern.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"242 ","pages":"142 - 165"},"PeriodicalIF":5.0,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50932174","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}
Fabian Fleischer, F. Haas, M. Altmann, Jakob Rom, Bettina Knoflach, M. Becht
Rock glaciers are cryo‐conditioned downslope‐creeping landforms in high mountains. Their dynamics are changing due to external factors influenced by climate change. Although there has been a growing scientific interest in mountain permafrost and thus in rock glaciers in recent years, their historical development, especially before the first alpine‐wide aerial image flights in the 1950s, has hardly been researched. Therefore, we utilize a historical stereophotogrammetric map from 1922 and historical flow velocity profiles (1938–1953) and relate them to data derived from historical aerial photographs and airborne laser scanning data in several time slices between 1953 and 2021. By doing so, the development of flow velocity, surface elevation changes, and frontal advance of the two lobes of the composite rock glacier Inner Ölgrube, Kaunertal, Austria, is analyzed and compared over almost a century. Results indicate an increased frontal advance in the laterally confined area of one lobe and a severe subsidence in the upper area of both lobes between 1922 and 1953. Whereas the former could be explained by a combination of the short warm phase in the 1940s and 1950s and the (subsurface) topography, the latter might be attributed to the strong melting of superimposed debris‐covered dead ice bodies, a relict of the Little Ice Age (LIA) glaciation. Both factors might also contribute to the increased flow velocities between 1938 and 1953, which are still recognizable in the 1953–1970 time step. Although both lobes follow a general similar trend, which is in line with the alpine‐wide trend of flow velocity acceleration in the 1990s, differences in the geomorphic development of the two lobes were identified. In addition to a slightly varying evolution of the flow velocities, the timing and magnitude of the volume changes are different. Furthermore, both lobes display a dissimilar mechanism of frontal advance over the entire study period. Because the external forcing is identical, the varying development might be attributed to variations in internal structure, bedrock topography, or upslope connection of the lobes. Due to the lateral constriction, the subsurface topography, and the LIA maximum extent of the glacier, it is assumed that the geomorphic development of the Innere Ölgruben rock glacier, particularly before 1953, represents a special case, and the results are not simply transferable to other rock glaciers.
{"title":"Combination of historical and modern data to decipher the geomorphic evolution of the Innere Ölgruben rock glacier, Kaunertal, Austria, over almost a century (1922–2021)","authors":"Fabian Fleischer, F. Haas, M. Altmann, Jakob Rom, Bettina Knoflach, M. Becht","doi":"10.1002/ppp.2178","DOIUrl":"https://doi.org/10.1002/ppp.2178","url":null,"abstract":"Rock glaciers are cryo‐conditioned downslope‐creeping landforms in high mountains. Their dynamics are changing due to external factors influenced by climate change. Although there has been a growing scientific interest in mountain permafrost and thus in rock glaciers in recent years, their historical development, especially before the first alpine‐wide aerial image flights in the 1950s, has hardly been researched. Therefore, we utilize a historical stereophotogrammetric map from 1922 and historical flow velocity profiles (1938–1953) and relate them to data derived from historical aerial photographs and airborne laser scanning data in several time slices between 1953 and 2021. By doing so, the development of flow velocity, surface elevation changes, and frontal advance of the two lobes of the composite rock glacier Inner Ölgrube, Kaunertal, Austria, is analyzed and compared over almost a century. Results indicate an increased frontal advance in the laterally confined area of one lobe and a severe subsidence in the upper area of both lobes between 1922 and 1953. Whereas the former could be explained by a combination of the short warm phase in the 1940s and 1950s and the (subsurface) topography, the latter might be attributed to the strong melting of superimposed debris‐covered dead ice bodies, a relict of the Little Ice Age (LIA) glaciation. Both factors might also contribute to the increased flow velocities between 1938 and 1953, which are still recognizable in the 1953–1970 time step. Although both lobes follow a general similar trend, which is in line with the alpine‐wide trend of flow velocity acceleration in the 1990s, differences in the geomorphic development of the two lobes were identified. In addition to a slightly varying evolution of the flow velocities, the timing and magnitude of the volume changes are different. Furthermore, both lobes display a dissimilar mechanism of frontal advance over the entire study period. Because the external forcing is identical, the varying development might be attributed to variations in internal structure, bedrock topography, or upslope connection of the lobes. Due to the lateral constriction, the subsurface topography, and the LIA maximum extent of the glacier, it is assumed that the geomorphic development of the Innere Ölgruben rock glacier, particularly before 1953, represents a special case, and the results are not simply transferable to other rock glaciers.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"21 - 3"},"PeriodicalIF":5.0,"publicationDate":"2022-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48795344","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}
Ji‐Woong Yang, J. Ahn, G. Iwahana, Nayeon Ko, Jihun Kim, Kyungmin Kim, A. Fedorov, Sang-young Han
Permafrost thawing as a result of global warming is expected to foster the biological remineralization of intact organic carbon and nitrogen and release greenhouse gas (GHG) into the atmosphere, which will have positive feedback for future global warming. However, GHG budgets and their controls in permafrost ground ice are not yet fully understood. This study aims to better understand the control mechanisms of GHG in ground ice by using new gas and chemistry data. In this study, we present new data on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) mixing ratios in three different ice wedges, Churapcha, Syrdakh, and Cyuie, located in central Yakutia, Siberia. The GHG mixing ratios in the studied ice wedges range from 0.0% to 13.8% CO2, 1.3–91.2 ppm CH4, and 0% and 0–1414 N2O. In particular, all three ice wedges demonstrate that ice‐wedge samples enriched in CH4 were depleted in N2O mixing ratios and vice versa. N2–O2–Ar compositions indicate that the studied ice wedges were most likely formed by dry snow or hoarfrost, not by freezing of snow meltwater, and the O2‐consuming biological metabolism was active. Most of the observed GHG mixing ratios cannot be explained without microbial metabolism. The inhibitory impact of denitrification products of nitrate (including N2O) could be an important control of the ice‐wedge CH4 mixing ratio.
{"title":"Origin of CO2, CH4, and N2O trapped in ice wedges in central Yakutia and their relationship","authors":"Ji‐Woong Yang, J. Ahn, G. Iwahana, Nayeon Ko, Jihun Kim, Kyungmin Kim, A. Fedorov, Sang-young Han","doi":"10.1002/ppp.2176","DOIUrl":"https://doi.org/10.1002/ppp.2176","url":null,"abstract":"Permafrost thawing as a result of global warming is expected to foster the biological remineralization of intact organic carbon and nitrogen and release greenhouse gas (GHG) into the atmosphere, which will have positive feedback for future global warming. However, GHG budgets and their controls in permafrost ground ice are not yet fully understood. This study aims to better understand the control mechanisms of GHG in ground ice by using new gas and chemistry data. In this study, we present new data on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) mixing ratios in three different ice wedges, Churapcha, Syrdakh, and Cyuie, located in central Yakutia, Siberia. The GHG mixing ratios in the studied ice wedges range from 0.0% to 13.8% CO2, 1.3–91.2 ppm CH4, and 0% and 0–1414 N2O. In particular, all three ice wedges demonstrate that ice‐wedge samples enriched in CH4 were depleted in N2O mixing ratios and vice versa. N2–O2–Ar compositions indicate that the studied ice wedges were most likely formed by dry snow or hoarfrost, not by freezing of snow meltwater, and the O2‐consuming biological metabolism was active. Most of the observed GHG mixing ratios cannot be explained without microbial metabolism. The inhibitory impact of denitrification products of nitrate (including N2O) could be an important control of the ice‐wedge CH4 mixing ratio.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"122 - 141"},"PeriodicalIF":5.0,"publicationDate":"2022-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43760214","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}
Hydrological processes within the alpine tundra of the Taiga Cordillera ecozone in northwestern Canada are poorly understood, yet these areas receive more precipitation per unit area than lowlands and sustain late summer and winter flow in large river systems when contributions from other areas are reduced. The objective of this study was to quantify the spatial and temporal variability in streamflow and groundwater recharge within an alpine tundra basin with discontinuous permafrost and explore the potential impacts of climate change on the timing and intensity of these hydrological processes. Hydrometric and remote sensing methods were used to complete a water balance assessment of the study basin and compare spatial and seasonal differences in inputs, outputs, runoff ratio, and runoff–recharge partitioning during the 2019 open water season. During the freshet, the basin received large daily melt volumes and responded with highly efficient runoff. Evapotranspiration became the primary means of water loss in the early summer but declined as the summer progressed. During the summer, groundwater discharge exceeded precipitation inputs and sustained headwater subbasin streamflow. Groundwater recharge occurred primarily via glaciofluvial upland infiltration during the freshet and channel bed infiltration during the summer. The partitioning of basin outputs between runoff and groundwater recharge was highly seasonal, with a freshet ratio favoring runoff (0.83) while the early and late summer favored recharge (0.28 and 0.17, respectively). As climate change continues, higher air temperatures and greater precipitation are expected for the study basin. Longer open water seasons and declining permafrost extent within the study basin will result in a greater proportion of input water routed to storage and/or groundwater recharge instead of runoff. Shrubification and treeline expansion may also increase evaporative losses from alpine tundra areas, reducing both rapid runoff and delayed aquifer recharge contributions important for larger rivers at lower elevation.
{"title":"Seasonally distinct runoff–recharge partitioning in an alpine tundra catchment","authors":"Geoffrey G. L. Kershaw, M. English, B. Wolfe","doi":"10.1002/ppp.2174","DOIUrl":"https://doi.org/10.1002/ppp.2174","url":null,"abstract":"Hydrological processes within the alpine tundra of the Taiga Cordillera ecozone in northwestern Canada are poorly understood, yet these areas receive more precipitation per unit area than lowlands and sustain late summer and winter flow in large river systems when contributions from other areas are reduced. The objective of this study was to quantify the spatial and temporal variability in streamflow and groundwater recharge within an alpine tundra basin with discontinuous permafrost and explore the potential impacts of climate change on the timing and intensity of these hydrological processes. Hydrometric and remote sensing methods were used to complete a water balance assessment of the study basin and compare spatial and seasonal differences in inputs, outputs, runoff ratio, and runoff–recharge partitioning during the 2019 open water season. During the freshet, the basin received large daily melt volumes and responded with highly efficient runoff. Evapotranspiration became the primary means of water loss in the early summer but declined as the summer progressed. During the summer, groundwater discharge exceeded precipitation inputs and sustained headwater subbasin streamflow. Groundwater recharge occurred primarily via glaciofluvial upland infiltration during the freshet and channel bed infiltration during the summer. The partitioning of basin outputs between runoff and groundwater recharge was highly seasonal, with a freshet ratio favoring runoff (0.83) while the early and late summer favored recharge (0.28 and 0.17, respectively). As climate change continues, higher air temperatures and greater precipitation are expected for the study basin. Longer open water seasons and declining permafrost extent within the study basin will result in a greater proportion of input water routed to storage and/or groundwater recharge instead of runoff. Shrubification and treeline expansion may also increase evaporative losses from alpine tundra areas, reducing both rapid runoff and delayed aquifer recharge contributions important for larger rivers at lower elevation.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"107 - 94"},"PeriodicalIF":5.0,"publicationDate":"2022-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47515093","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}
A new software package, ICE2020 of the GALO basin modeling system, is used here to model the thermal evolution of permafrost zones in a sedimentary section of the Tyumen SG‐6 well in the Koltogor–Urengoy graben of the West Siberia Basin. Reconstruction of permafrost evolution during the last 3.5 Ma is considered as the final stage of the modeling procedure of the basin, the history of which began with continental rifting in the Late Permian. The modeling uses a real sedimentary section of the basin with the correct lithological composition of its rocks. Application of the ICE2020 package made it possible to evaluate the influence of sedimentation on the formation of permafrost zones. The calculations showed that climate variations during the Late Pliocene–Holocene led to a reduction in rock temperatures by 15–20°C in the upper 1,500 m of the sedimentary section of the SG‐6 well and by 5–10°C in the deeper layers of the section. At the same time, the results of calculations with a climate curve limited to the last 50,000 and 100,000 years differ markedly from simulations with a climate curve of the last 3.5 Ma.
{"title":"Thermal history of the permafrost zone in the vicinity of the deep Tyumen SG‐6 well, West Siberian Basin","authors":"Y. Galushkin","doi":"10.1002/ppp.2168","DOIUrl":"https://doi.org/10.1002/ppp.2168","url":null,"abstract":"A new software package, ICE2020 of the GALO basin modeling system, is used here to model the thermal evolution of permafrost zones in a sedimentary section of the Tyumen SG‐6 well in the Koltogor–Urengoy graben of the West Siberia Basin. Reconstruction of permafrost evolution during the last 3.5 Ma is considered as the final stage of the modeling procedure of the basin, the history of which began with continental rifting in the Late Permian. The modeling uses a real sedimentary section of the basin with the correct lithological composition of its rocks. Application of the ICE2020 package made it possible to evaluate the influence of sedimentation on the formation of permafrost zones. The calculations showed that climate variations during the Late Pliocene–Holocene led to a reduction in rock temperatures by 15–20°C in the upper 1,500 m of the sedimentary section of the SG‐6 well and by 5–10°C in the deeper layers of the section. At the same time, the results of calculations with a climate curve limited to the last 50,000 and 100,000 years differ markedly from simulations with a climate curve of the last 3.5 Ma.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"108 - 121"},"PeriodicalIF":5.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45184245","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}
Salts are pervasive throughout the Transantarctic Mountains cold desert soils and are derived primarily from atmospheric sources. Their composition is varied and dependent on local or regional climatic conditions. Their presence within soil profiles ranges from small flecks to continuous salt horizons and their abundance and distribution have a distinct relationship with climatic attributes and land surface age which extends back to the Miocene. While liquid water is seldom present, salts are present in saturated solutions surrounding mineral grains in the soil and may move deeply into the soil or underlying icy permafrost. Extensive ground surface salt efflorescence occurs on freshly exposed surfaces that have been disturbed by human activities, the salts being derived from within the thawed permafrost ice.
{"title":"A review of salt occurrences in soils of the Transantarctic Mountains, Antarctica","authors":"I. B. Campbell, D. S. Sheppard","doi":"10.1002/ppp.2175","DOIUrl":"https://doi.org/10.1002/ppp.2175","url":null,"abstract":"Salts are pervasive throughout the Transantarctic Mountains cold desert soils and are derived primarily from atmospheric sources. Their composition is varied and dependent on local or regional climatic conditions. Their presence within soil profiles ranges from small flecks to continuous salt horizons and their abundance and distribution have a distinct relationship with climatic attributes and land surface age which extends back to the Miocene. While liquid water is seldom present, salts are present in saturated solutions surrounding mineral grains in the soil and may move deeply into the soil or underlying icy permafrost. Extensive ground surface salt efflorescence occurs on freshly exposed surfaces that have been disturbed by human activities, the salts being derived from within the thawed permafrost ice.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"287 - 295"},"PeriodicalIF":5.0,"publicationDate":"2022-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42017502","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}
Aufeis is a common phenomenon in cold regions of the Northern Hemisphere that develops during winter by successive water overflow and freezing on ice‐covered surfaces. Most studies on aufeis occurrence focus on regions in North America and Siberia, while research in High Mountain Asia (HMA) is still in an exploratory phase. This study investigates the extent and dynamics of icing processes and aufeis in the Tso Moriri basin, eastern Ladakh, India. Based on a combination of 235 Landsat 5 TM/8 OLI and Sentinel‐2 imagery from 2008 to 2021 the occurrence of icing and aufeis was classified using a random forest classifier. A total of 27 frequently occurring aufeis fields with an average maximum extent of 9 km2 were identified, located at a mean elevation of 4,700 m a.s.l. Temporal patterns show a distinct accumulation phase (icing) between November and April, and a melting phase lasting from May until July. Icing is characterized by high seasonal and inter‐annual variability. Successive water overflow mainly occurs between January and March and seems to be related to diurnal freeze–thaw‐cycles, whereas higher daytime temperatures result in larger icing areas. Aufeis feeding sources are often located within or in close vicinity to wetland areas, while vegetation is largely absent on surfaces with frequent aufeis formation. These interactions require more attention in future research. In addition, this study shows the high potential of a machine learning approach to monitor icing processes and aufeis, which can be transferred to other regions.
Aufeis是北半球寒冷地区的一种常见现象，在冬季，由于水连续溢出和冰层表面结冰而形成。大多数关于aufeis发生的研究集中在北美和西伯利亚地区，而亚洲高山地区的研究仍处于探索阶段。本研究调查了印度拉达克东部措莫里里盆地结冰过程和aufei的范围和动力学。基于2008年至2021年235幅Landsat 5 TM/8 OLI和Sentinel‐2图像的组合，使用随机森林分类器对结冰和aufeis的发生进行了分类。共确定了27个频繁出现的aufeis油田，平均最大面积为9km2，位于平均海拔4700 m a.s.l.时间模式显示，11月至4月之间有一个明显的积累阶段（结冰），5月至7月为融化阶段。结冰的特点是季节性和年际变化较大。连续的水溢流主要发生在1月至3月之间，似乎与白天的冻融循环有关，而白天温度越高，结冰面积越大。Aufeis的食物来源通常位于湿地内或附近，而Aufeis频繁形成的表面基本上没有植被。这些相互作用需要在未来的研究中给予更多关注。此外，这项研究表明，机器学习方法在监测结冰过程和aufeis方面具有很高的潜力，可以转移到其他地区。
{"title":"Spatial and temporal dynamics of aufeis in the Tso Moriri basin, eastern Ladakh, India","authors":"Dagmar Brombierstäudl, S. Schmidt, M. Nüsser","doi":"10.1002/ppp.2173","DOIUrl":"https://doi.org/10.1002/ppp.2173","url":null,"abstract":"Aufeis is a common phenomenon in cold regions of the Northern Hemisphere that develops during winter by successive water overflow and freezing on ice‐covered surfaces. Most studies on aufeis occurrence focus on regions in North America and Siberia, while research in High Mountain Asia (HMA) is still in an exploratory phase. This study investigates the extent and dynamics of icing processes and aufeis in the Tso Moriri basin, eastern Ladakh, India. Based on a combination of 235 Landsat 5 TM/8 OLI and Sentinel‐2 imagery from 2008 to 2021 the occurrence of icing and aufeis was classified using a random forest classifier. A total of 27 frequently occurring aufeis fields with an average maximum extent of 9 km2 were identified, located at a mean elevation of 4,700 m a.s.l. Temporal patterns show a distinct accumulation phase (icing) between November and April, and a melting phase lasting from May until July. Icing is characterized by high seasonal and inter‐annual variability. Successive water overflow mainly occurs between January and March and seems to be related to diurnal freeze–thaw‐cycles, whereas higher daytime temperatures result in larger icing areas. Aufeis feeding sources are often located within or in close vicinity to wetland areas, while vegetation is largely absent on surfaces with frequent aufeis formation. These interactions require more attention in future research. In addition, this study shows the high potential of a machine learning approach to monitor icing processes and aufeis, which can be transferred to other regions.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"81 - 93"},"PeriodicalIF":5.0,"publicationDate":"2022-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42343097","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}
Current climate change in the Arctic is unprecedented in the instrumental record, with profound consequences for the environment and landscape. In Arctic Sweden, aeolian sand dunes have been impacted by climatic changes since their initial formation after the retreat of the last glacial ice sheet. Dune type, location and orientation can therefore be used to explore past wind patterns and landscape destabilisation in this sensitive area. However, knowledge of the full spatial extent and characteristics of these dunes is limited by their inaccessibility and dense vegetation cover. Geographic object‐based image analysis (GEOBIA) permits the semi‐automatic creation of reproducible parameter‐based objects and can be an appropriate means to systematically and spatially map these dunes remotely. Here, a digital elevation model (DEM) and its derivatives, such as slope and curvature, were segmented in a GEOBIA context, enabling the identification and mapping of aeolian sand dunes in Arctic Sweden. Analysis of the GEOBIA‐derived and expert‐accepted polygons affirms the prevalence of parabolic dune type and reveals the coexistence of simple dunes with large coalesced systems. Furthermore, mapped dune orientations and relationships to other geomorphological features were used to explore past wind directions and to identify sediment sources as well as the reasons for sand availability. The results indicate that most dune systems in Arctic Sweden were initially supplied by glaciofluvial and fluvial disturbances of sandy esker systems. Topographic control of wind direction is the dominant influence on dune orientation. Further, our approach shows that analysing the GEOBIA‐derived dune objects in their geomorphological context paves the way for successfully investigating aeolian sand dune location, type and orientation in Arctic Sweden, thereby facilitating the understanding of post‐glacial landscape (in)stability and evolution in the area.
{"title":"Geographic object‐based image analysis (GEOBIA) of the distribution and characteristics of aeolian sand dunes in Arctic Sweden","authors":"Melanie Stammler, T. Stevens, D. Hölbling","doi":"10.1002/ppp.2169","DOIUrl":"https://doi.org/10.1002/ppp.2169","url":null,"abstract":"Current climate change in the Arctic is unprecedented in the instrumental record, with profound consequences for the environment and landscape. In Arctic Sweden, aeolian sand dunes have been impacted by climatic changes since their initial formation after the retreat of the last glacial ice sheet. Dune type, location and orientation can therefore be used to explore past wind patterns and landscape destabilisation in this sensitive area. However, knowledge of the full spatial extent and characteristics of these dunes is limited by their inaccessibility and dense vegetation cover. Geographic object‐based image analysis (GEOBIA) permits the semi‐automatic creation of reproducible parameter‐based objects and can be an appropriate means to systematically and spatially map these dunes remotely. Here, a digital elevation model (DEM) and its derivatives, such as slope and curvature, were segmented in a GEOBIA context, enabling the identification and mapping of aeolian sand dunes in Arctic Sweden. Analysis of the GEOBIA‐derived and expert‐accepted polygons affirms the prevalence of parabolic dune type and reveals the coexistence of simple dunes with large coalesced systems. Furthermore, mapped dune orientations and relationships to other geomorphological features were used to explore past wind directions and to identify sediment sources as well as the reasons for sand availability. The results indicate that most dune systems in Arctic Sweden were initially supplied by glaciofluvial and fluvial disturbances of sandy esker systems. Topographic control of wind direction is the dominant influence on dune orientation. Further, our approach shows that analysing the GEOBIA‐derived dune objects in their geomorphological context paves the way for successfully investigating aeolian sand dune location, type and orientation in Arctic Sweden, thereby facilitating the understanding of post‐glacial landscape (in)stability and evolution in the area.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"22 - 36"},"PeriodicalIF":5.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42847007","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 Antarctic continent is a crucial area for ultimate determination of permafrost extent on Earth, and its solution depends on the theoretical assumptions adopted. In fact, it ranges from 0.022 × 106 to 14 × 106 km2. This level of inaccuracy is unprecedented in the Earth sciences. The novelty of the present study consists in determining the extent of Antarctic permafrost not based exclusively on empirical studies but on universal criteria resulting from the definition of permafrost as the thermal state of the lithosphere, which was applied for the first time to this continent. The area covered by permafrost in Antarctica is ca. 13.9 million km2, that is its entire surface. This result was also made possible due to the first clear determination of the boundaries and area of the continent. The Antarctic area includes (a) rocky subsurface with (b) continental ice‐sheets and (c) shelf glaciers, which, due to their terrigenous origin and belonging to the lithosphere, belongs to the continent in the same way. Antarctica is covered by continuous permafrost, either in a frozen or in a cryotic state. This also significantly influences delimitation of the global extent of permafrost, which can therefore be defined much more accurately. The proposed ice reclassification and its transfer from the hydrosphere to the lithosphere will allow the uniform treatment of ice in the Earth sciences, both on Earth and on other celestial bodies.
{"title":"Area and borders of Antarctic and permafrost—A review and synthesis","authors":"W. Dobiński, J. E. Szafraniec, Bartłomiej Szypuła","doi":"10.1002/ppp.2170","DOIUrl":"https://doi.org/10.1002/ppp.2170","url":null,"abstract":"The Antarctic continent is a crucial area for ultimate determination of permafrost extent on Earth, and its solution depends on the theoretical assumptions adopted. In fact, it ranges from 0.022 × 106 to 14 × 106 km2. This level of inaccuracy is unprecedented in the Earth sciences. The novelty of the present study consists in determining the extent of Antarctic permafrost not based exclusively on empirical studies but on universal criteria resulting from the definition of permafrost as the thermal state of the lithosphere, which was applied for the first time to this continent. The area covered by permafrost in Antarctica is ca. 13.9 million km2, that is its entire surface. This result was also made possible due to the first clear determination of the boundaries and area of the continent. The Antarctic area includes (a) rocky subsurface with (b) continental ice‐sheets and (c) shelf glaciers, which, due to their terrigenous origin and belonging to the lithosphere, belongs to the continent in the same way. Antarctica is covered by continuous permafrost, either in a frozen or in a cryotic state. This also significantly influences delimitation of the global extent of permafrost, which can therefore be defined much more accurately. The proposed ice reclassification and its transfer from the hydrosphere to the lithosphere will allow the uniform treatment of ice in the Earth sciences, both on Earth and on other celestial bodies.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"37 - 51"},"PeriodicalIF":5.0,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43390481","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}
Lingxiao Wang, Lin Zhao, Huayun Zhou, Shibo Liu, G. Hu, Zhibin Li, Chong Wang, Jianting Zhao
The thawing of ice‐rich permafrost has attracted considerable attention in recent years. In this study, we analyzed both the ground surface deformation time series spanning 6 years, derived through the SBAS‐InSAR technique on the Qinghai‐Xizang (Tibet) Plateau (QTP), and the long‐term active layer soil temperature and moisture in situ observations and their relationships. The results showed that long‐term subsidence velocity directly represents the melting of ground ice instead of the thickening rate of the active layer by a quantitative analysis of both terrain subsidence velocity and active layer thickening rate and the increase in liquid water at the bottom of the active layer. Ice‐poor permafrost thawing does not result in distinct subsidence, although the active layer deepening rate can be very high. The spatial analysis reveals that long‐term deformation velocities are large in the foothills and on gentle slopes (1–5 degrees) and are closely related to geomorphological conditions, which could regulate the soil properties and ground ice content. These findings improve the understanding of the thawing degradation of icy permafrost and promote method developments for the automated mapping of ground ice melting in permafrost environments.
{"title":"Evidence of ground ice melting detected by InSAR and in situ monitoring over permafrost terrain on the Qinghai‐Xizang (Tibet) Plateau","authors":"Lingxiao Wang, Lin Zhao, Huayun Zhou, Shibo Liu, G. Hu, Zhibin Li, Chong Wang, Jianting Zhao","doi":"10.1002/ppp.2171","DOIUrl":"https://doi.org/10.1002/ppp.2171","url":null,"abstract":"The thawing of ice‐rich permafrost has attracted considerable attention in recent years. In this study, we analyzed both the ground surface deformation time series spanning 6 years, derived through the SBAS‐InSAR technique on the Qinghai‐Xizang (Tibet) Plateau (QTP), and the long‐term active layer soil temperature and moisture in situ observations and their relationships. The results showed that long‐term subsidence velocity directly represents the melting of ground ice instead of the thickening rate of the active layer by a quantitative analysis of both terrain subsidence velocity and active layer thickening rate and the increase in liquid water at the bottom of the active layer. Ice‐poor permafrost thawing does not result in distinct subsidence, although the active layer deepening rate can be very high. The spatial analysis reveals that long‐term deformation velocities are large in the foothills and on gentle slopes (1–5 degrees) and are closely related to geomorphological conditions, which could regulate the soil properties and ground ice content. These findings improve the understanding of the thawing degradation of icy permafrost and promote method developments for the automated mapping of ground ice melting in permafrost environments.","PeriodicalId":54629,"journal":{"name":"Permafrost and Periglacial Processes","volume":"34 1","pages":"52 - 67"},"PeriodicalIF":5.0,"publicationDate":"2022-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46694421","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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