Journal of Glaciology最新文献_第10页

Characterising ice slabs in firn using seismic full waveform inversion, a sensitivity study 利用地震全波形反演的灵敏度研究在firn中表征冰板

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-25 DOI: 10.1017/jog.2023.30

E. Pearce, A. Booth, S. Rost, P. Sava, T. Konuk, A. Brisbourne, B. Hubbard, I. Jones

{"title":"Characterising ice slabs in firn using seismic full waveform inversion, a sensitivity study","authors":"E. Pearce, A. Booth, S. Rost, P. Sava, T. Konuk, A. Brisbourne, B. Hubbard, I. Jones","doi":"10.1017/jog.2023.30","DOIUrl":"https://doi.org/10.1017/jog.2023.30","url":null,"abstract":"\u0000 The density structure of firn has implications for hydrological and climate modelling, and ice-shelf stability. The structure of firn can be evaluated from depth models of seismic velocity, widely obtained with Herglotz–Wiechert inversion (HWI), an approach that considers the slowness of refracted seismic arrivals. However, HWI is strictly appropriate only for steady-state firn profiles and the inversion accuracy can be compromised where firn contains ice layers. In these cases, full waveform inversion (FWI) may yield more success than HWI. FWI extends HWI capabilities by considering the full seismic waveform and incorporates reflected arrivals. Using synthetic firn density profiles, assuming both steady- and non-steady-state accumulation, we show that FWI outperforms HWI for detecting ice slab boundaries (5–80 m thick, 5–80 m deep) and velocity anomalies within firn. FWI can detect slabs thicker than one wavelength (here, 20 m, assuming a maximum frequency of 60 Hz) but requires the starting velocity model to be accurate to ±2.5%. We recommend for field practice that the shallowest layers of velocity models are constrained with ground-truth data. Nonetheless, FWI shows advantages over established methods, and should be considered when the characterisation of firn ice slabs is the goal of the seismic survey.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41666561","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}

引用次数: 1

JOG volume 69 issue 275 Cover and Front matter JOG第69卷第275期封面和封面问题

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-23 DOI: 10.1017/jog.2023.31

引用次数: 0

JOG volume 69 issue 275 Cover and Back matter JOG卷69期275封面和封底

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-23 DOI: 10.1017/jog.2023.32

引用次数: 0

Automated prediction of wet-snow avalanche activity in the Swiss Alps 瑞士阿尔卑斯山湿雪崩活动的自动预测

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-18 DOI: 10.1017/jog.2023.24

M. Hendrick, F. Techel, M. Volpi, Tasko Olevski, Cristina Pérez-Guillén, A. Herwijnen, J. Schweizer

{"title":"Automated prediction of wet-snow avalanche activity in the Swiss Alps","authors":"M. Hendrick, F. Techel, M. Volpi, Tasko Olevski, Cristina Pérez-Guillén, A. Herwijnen, J. Schweizer","doi":"10.1017/jog.2023.24","DOIUrl":"https://doi.org/10.1017/jog.2023.24","url":null,"abstract":"\u0000 Wet-snow avalanches are triggered by the infiltration of liquid water which weakens the snowpack. Wet-snow avalanches are among the most destructive avalanches, yet their release mechanism is not sufficiently understood for a process-based prediction model. Therefore, we followed a data-driven approach and developed a random forest model, depending on slope aspect, to predict the local wet-snow avalanche activity at the locations of 124 automated weather stations distributed throughout the Swiss Alps. The input variables were the snow and weather data recorded by the stations over the past 20 years. The target variable was based on manual observations over the same 20-year period. To filter out erroneous reports, we defined the days with wet-snow avalanches in a stringent manner, selecting only the most extreme active or inactive days, which reduced the size of the dataset but increased the reliability of the target variable. The model was trained with weather variables and variables computed from simulated snow stratigraphy in 38\u0000 \u0000 $^circ$\u0000 \u0000 \u0000 slopes facing the 4 cardinal directions. While model development and validation were done in nowcast mode, we also studied model performance in 24-hour forecast mode by using input variables computed from a numerical weather prediction (NWP) model. Overall, the performance was good in both nowcast and forecast mode (f1-score around 0.8). To assess model performance beyond the stringent definition of wet-snow avalanche days, we compared model predictions to wet-snow avalanche activity over the entire Swiss Alps, based on the raw data over 8 winters. We obtained a Spearman correlation coefficient of 0.71. Hence, our model represents a step toward the application of support tools in operational wet-snow avalanche forecasting.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44182541","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}

引用次数: 3

Snow and avalanche climates in the French Alps using avalanche problem frequencies 使用雪崩问题频率的法国阿尔卑斯山的雪和雪崩气候

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-18 DOI: 10.1017/jog.2023.23

B. Reuter, P. Hagenmuller, N. Eckert

{"title":"Snow and avalanche climates in the French Alps using avalanche problem frequencies","authors":"B. Reuter, P. Hagenmuller, N. Eckert","doi":"10.1017/jog.2023.23","DOIUrl":"https://doi.org/10.1017/jog.2023.23","url":null,"abstract":"\u0000 Avalanches result from an interaction of weather and terrain, where past weather and internal snow cover processes play important roles. So far, climatology was mainly based on weather data, as regional snow instability information, such as avalanche activity, is scarce on climatological time scales. We present a new approach to create a snow avalanche climatology from simulations of avalanche problem types based on snow cover simulations of reanalysis data and a cluster analysis. Analyzing the winters between 1958 and 2020 in the French Alps, wet-snow situations dominated natural release. Dry-snow situations with non-persistent and persistent weak layers occurred each on at least one third of the days. Four typical patterns of avalanche problem types were identified. They follow the main orography with more new snow situations in the northern regions and more cases of persistent weak layers in inner-Alpine regions. In the front-ranges and in southern regions wet-snow situations occurred early in winter – typical for coastal snow climates. Agreement with the standard snow climate classification and the geography of the French Alps suggests that mountain regions with similar conditions can now be outlined. This method for snow avalanche climatology will inform avalanche forecasting and facilitate climate change impact studies.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47829587","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}

引用次数: 0

Firn aquifer water discharges into crevasses across Southeast Greenland 冷杉含水层的水排入格陵兰岛东南部的决口

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-17 DOI: 10.1017/jog.2023.25

Eric Cicero, K. Poinar, R. Jones-Ivey, A. Petty, Jeanette M. Sperhac, A. Patra, J. Briner

{"title":"Firn aquifer water discharges into crevasses across Southeast Greenland","authors":"Eric Cicero, K. Poinar, R. Jones-Ivey, A. Petty, Jeanette M. Sperhac, A. Patra, J. Briner","doi":"10.1017/jog.2023.25","DOIUrl":"https://doi.org/10.1017/jog.2023.25","url":null,"abstract":"\u0000 In Southeast Greenland, summer melt and high winter snowfall rates give rise to firn aquifers: vast stores of meltwater buried beneath the ice-sheet surface. Previous detailed studies of a single Greenland firn aquifer site suggest that the water drains into crevasses, but this is not known at a regional scale. We develop and use a tool in Ghub, an online gateway of shared datasets, tools and supercomputing resources for glaciology, to identify crevasses from elevation data collected by NASA's Airborne Topographic Mapper across 29000 km2 of Southeast Greenland. We find crevasses within 3 km of the previously mapped downglacier boundary of the firn aquifer at 20 of 25 flightline crossings. Our data suggest that crevasses widen until they reach the downglacier boundary of the firn aquifer, implying that crevasses collect firn-aquifer water, but we did not find this trend with statistical significance. The median crevasse width, 27 meters, implies an aspect ratio consistent with the crevasses reaching the bed. Our results support the idea that most water in Southeast Greenland firn aquifers drains through crevasses. Less common fates are discharge at the ice-sheet surface (3 of 25 sites) and refreezing at the aquifer bottom (1 of 25 sites).","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46462169","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}

引用次数: 0

Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations 格陵兰NEEM冰芯的基底碎屑:亚冰盖地质、基底冰过程和冰盖振荡的窗口

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-17 DOI: 10.1017/jog.2022.122

P. Blard, M. Protin, J. Tison, F. Fripiat, D. Dahl-Jensen, J. Steffensen, W. Mahaney, P. Bierman, A. Christ, L. Corbett, V. Debaille, T. Rigaudier, P. Claeys

{"title":"Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations","authors":"P. Blard, M. Protin, J. Tison, F. Fripiat, D. Dahl-Jensen, J. Steffensen, W. Mahaney, P. Bierman, A. Christ, L. Corbett, V. Debaille, T. Rigaudier, P. Claeys","doi":"10.1017/jog.2022.122","DOIUrl":"https://doi.org/10.1017/jog.2022.122","url":null,"abstract":"Abstract We present new data from the debris-rich basal ice layers of the NEEM ice core (NW Greenland). Using mineralogical observations, SEM imagery, geochemical data from silicates (meteoric 10Be, εNd, 87Sr/86Sr) and organic material (C/N, δ13C), we characterize the source material, succession of previous glaciations and deglaciations and the paleoecological conditions during ice-free episodes. Meteoric 10Be data and grain features indicate that the ice sheet interacted with paleosols and eroded fresh bedrock, leading to mixing in these debris-rich ice layers. Our analysis also identifies four successive stages in NW Greenland: (1) initial preglacial conditions, (2) glacial advance 1, (3) glacial retreat and interglacial conditions and (4) glacial advance 2 (current ice-sheet development). C/N and δ13C data suggest that deglacial environments favored the development of tundra and taiga ecosystems. These two successive glacial fluctuations observed at NEEM are consistent with those identified from the Camp Century core basal sediments over the last 3 Ma. Further inland, GRIP and GISP2 summit sites have remained glaciated more continuously than the western margin, with less intense ice-substratum interactions than those observed at NEEM.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"69 1","pages":"1011 - 1029"},"PeriodicalIF":3.4,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48297398","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}

引用次数: 0

Robust reconstruction of glacier beds using transient 2D assimilation with Stokes 利用Stokes瞬态二维同化对冰川床进行鲁棒重建

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-12 DOI: 10.1017/jog.2023.26

Samuel J. Cook, F. Gillet-Chaulet, J. Fürst

引用次数: 0

The first cultivation of the glacier ice alga Ancylonema alaskanum (Zygnematophyceae, Streptophyta): differences in morphology and photophysiology of field vs laboratory strain cells 冰川冰藻alaskanum (zynematophyceae，链藻目)的首次培养:野外与实验室菌株细胞形态和光生理的差异

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-10 DOI: 10.1017/jog.2023.22

D. Remias, Lenka Procházková

{"title":"The first cultivation of the glacier ice alga Ancylonema alaskanum (Zygnematophyceae, Streptophyta): differences in morphology and photophysiology of field vs laboratory strain cells","authors":"D. Remias, Lenka Procházková","doi":"10.1017/jog.2023.22","DOIUrl":"https://doi.org/10.1017/jog.2023.22","url":null,"abstract":"Abstract Melting glacier surfaces are unique ecosystems for specialized microbes, frequently harbouring blooms of microalgae with pigments contributing to the darkening of ice surfaces, reducing albedo and enhancing melt rates. The main cause of this phenomenon is algae of the genus Ancylonema. Prior investigation depended on field-collected material because these algae resisted cultivation. To enhance research on how these algae dominate melting ice, we established a strain of Ancylonema alaskanum from an alpine glacier and exposed to temperatures around the freezing point at irradiations of ~10% of full sunlight. The morphology of the culture changed, with the cells becoming longer and turning green by losing their brownish pigmentation, indicating that these dark phenols are crucial for survival in the cryosphere. Photophysiological comparisons of strain and glacial material showed adaptation of the photosynthetic apparatus to prevailing conditions. This laboratorial strain opens possibilities for a wide range of comparative ‘omics’ research.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":"69 1","pages":"1080 - 1084"},"PeriodicalIF":3.4,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46614258","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}

引用次数: 3

Ice aprons on steep high-alpine slopes: insights from the Mont-Blanc massif, Western Alps 陡峭的高山斜坡上的冰围裙:从西阿尔卑斯勃朗峰地块的视角

IF 3.4 3区地球科学

Journal of Glaciology Pub Date : 2023-05-09 DOI: 10.1017/jog.2023.15

L. Ravanel, G. Guillet, S. Kaushik, S. Preunkert, E. Malet, F. Magnin, E. Trouvé, M. Montagnat, Yajing Yan, P. Deline

{"title":"Ice aprons on steep high-alpine slopes: insights from the Mont-Blanc massif, Western Alps","authors":"L. Ravanel, G. Guillet, S. Kaushik, S. Preunkert, E. Malet, F. Magnin, E. Trouvé, M. Montagnat, Yajing Yan, P. Deline","doi":"10.1017/jog.2023.15","DOIUrl":"https://doi.org/10.1017/jog.2023.15","url":null,"abstract":"\u0000 Ice aprons are defined as very small ice bodies covering steep rock slopes. They have only been the subject of increased scientific interest for a few years, despite the fact that they are a condition for mountaineering and obvious elements in the high-alpine landscapes. However, very little is known about their distribution, evolution and physical characteristics. In this paper, we review the existing knowledge on ice aprons, which have almost exclusively been investigated in the Mont-Blanc massif, Western Alps. We supplement this review with novel results from recent surveys of ice aprons. We used a wide array of methodologies, from remote sensing (multi-source imagery) to in situ (stakes and thermal monitoring) and laboratory (radiocarbon dating and texture analysis) glaciological investigations. In the Mont-Blanc massif, ice aprons occupy 4.2 km2 within the alpine permafrost zone. Temperature measured at the ice–rock interface is indeed largely negative. Thinness of ice aprons coupled with the cold context implies a quasi-stationary shear regime without basal Sliding. Only ice at the surface can possibly melt in warm periods. After a shrinking period from the end of the Little Ice Age to the mid-to-late-1960s, ice aprons experienced a short period of expansion, followed by an accelerated shrinkage since the beginning of the 21st century. This shrinkage now favours rockfall triggering and poses a serious threat to a glaciological heritage since ice aprons host several-thousand-year-old ice. Finally, we synthesize this information to assess the existing definition of ice aprons, and propose some future research directions.","PeriodicalId":15981,"journal":{"name":"Journal of Glaciology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42130255","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}

引用次数: 1