Geografiska Annaler Series A-Physical Geography最新文献

{"title":"Evaluating millennial to contemporary time scales of glacier change in Val Viola, Central Italian Alps","authors":"R. Scotti, F. Brardinoni","doi":"10.1080/04353676.2018.1491312","DOIUrl":"https://doi.org/10.1080/04353676.2018.1491312","url":null,"abstract":"ABSTRACT To improve current understanding of ongoing deglaciation dynamics in relation to climatic forcing, it is critical to build long-term series of climate and glacier changes. This task is typically hampered by availability and resolution of Quaternary glacier paleo-reconstructions. To explore opportunities and challenges, we present a case study from Val Viola, which integrates area, volume and ELA changes across a 13k-year time window, including four Younger Dryas–Early Holocene glacier stadials and eight post-LIA periods. Results suggest that relevant shifts in climatic forcing associated with the Pleistocene–Holocene transition and post-LIA deglaciation phases are of comparable magnitude, with an atmospheric temperature increase of about 1.5–2°C. Post-LIA decline in glacierized areas (68.9 ± 6%) is comparable with retreat rates recorded in other Italian glaciers, but is greater than elsewhere in the Alps, where glaciers are comparably larger. Glacier stability in the particularly warm 2007–2015 period testifies to the decoupling attained by small glaciers from synoptic atmospheric conditions. We argue that this is caused by enhanced wind drift and avalanche accumulation, occurred in response to morphological changes on ice surfaces following progressive glacier shrinking. This positive feedback not only could delay glacier extinction in certain physiographic settings but also could introduce bias in paleo-glaciological reconstructions of climatic conditions.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89211282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An update on recent glacier changes in Mexico using Sentinel-2A data","authors":"Bijeesh KV, Shanshan Wang","doi":"10.1080/04353676.2018.1478672","DOIUrl":"https://doi.org/10.1080/04353676.2018.1478672","url":null,"abstract":"ABSTRACT This study estimated the recent evolution of three glacierized stratovolcanoes – namely Volcán Iztaccíhuatl, Volcán Popocatépetl and Volcán Citlaltépetl – in South-central Mexico using Landsat and Sentinel-2A satellite data acquired between 1973 and 2017. These three glaciers are influenced by various factors such as climate change, volcanic eruption and pollution. Three key climate variables, which control the presence of glacier coverage – air temperature, precipitation and humidity – were also analysed. Among these three volcanoes, only Volcán Iztaccíhuatl and Volcán Citlaltépetl have ice-covered areas since the late 1990s and Volcán Popocatépetl has lost its glaciers due to volcanic eruption, even though the glacier shrinkage has started long before the appearance of eruptive products. An overall glacier area loss of 75% has been observed for the period between 1973 and 2017. Shrinkage of Volcán Citlaltépetl (66%) is comparable with the retreat observed in the tropical Andes of Peru and Bolivia during the same period. Observed trends in the air temperature were not very significant for all the three glaciers studied whereas a substantial rise in relative humidity (+0.11%/year) was observed. Trends in precipitation were different for Citlaltépetl (+7.8 mm/year) and the other two volcano-glaciers (−5.1 mm/year).","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87452272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigations on blockfields and related landforms at Blåhø (Southern Norway) using Schmidt-hammer exposure-age dating: palaeoclimatic and morphodynamic implications","authors":"P. Marr, S. Winkler, J. Löffler","doi":"10.1080/04353676.2018.1474350","DOIUrl":"https://doi.org/10.1080/04353676.2018.1474350","url":null,"abstract":"ABSTRACT Schmidt-hammer exposure-age dating (SHD) was performed on blockfields and related landforms on Blåhø, Southern Norway. By developing a linear high-precision age-calibration curve through young and old control points of known age from terrestrial cosmogenic nuclide dating, it was possible to gain landform age estimates based on Schmidt hammer R-values. The aim of this study is to relate formation and subsequent stabilization of the landforms investigated to climate fluctuations since the Last Glacial Maximum (LGM) and to explore the palaeoclimatic implication of such periglacial landforms. The SHD ages range from 19.14 ± 0.91 ka for the Rundhø blockfield to 5.32 ± 0.73 ka for the lowest elevation rock-slope failure. The R-value frequency distributions obtained on the landforms studied indicate complex, long-term formation histories. Landforms above 1450 m a.s.l. share comparable SHD ages and seem to have stabilized during the Karmøy/Bremanger readvance (∼18.5–16.5 ka). The lower elevation rock-slope failures most likely occurred during the Bølling-Allerød interstadial (∼14.7–12.9 ka) and the Holocene Thermal Maximum (∼8.0–5.0 ka). The results contrast with the established model that rock-slope failures occur within the first millennia following deglaciation. Instead of the inferred ice coverage above 1450 m a.s.l. until 15.0 ± 1.0 10Be ka, our results suggest severe periglacial and ice-free conditions occurred earlier. Landforms above 1450 m a.s.l. do not show any form of reactivation during cold periods within the Late Glacial and Holocene. Our SHD results suggest that the landforms investigated were (at least partly) generated prior the LGM and survived beneath cold-based ice or were located on nunataks.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89267011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Holocene soil processes and the first evidence for ferruginous rhizoconcretions in cool subpolar environments of the Faroe Islands","authors":"R. Pokorný, K. Edwards, L. Krmíček, D. Všianský, Petra Dáňová","doi":"10.1080/04353676.2018.1463142","DOIUrl":"https://doi.org/10.1080/04353676.2018.1463142","url":null,"abstract":"ABSTRACT The Faroe Islands are characterized by high rates of Holocene geomorphological activity and demonstrable vegetation change, including substantial peat formation. Pedogenesis, especially in the late Holocene, is less well known. Numerous ferruginous rhizoconcretions consisting predominantly of Fe-oxyhydroxides were identified in loam and silty sands in Søltuvík on the island of Sandoy, dated prior to AD 1000. Their formation is related to intensive podzolization and they take the form of the source woody vegetation. The sub-fossil material represents the first evidence for ferruginous rhizoconcretions in the Faroese archipelago.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89458106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphoclimatic controls of contemporary chemical and mechanical denudation in a boreal-oceanic drainage basin system in central Norway (Homla drainage basin, Trøndelag)","authors":"A. Beylich, K. Laute","doi":"10.1080/04353676.2017.1407219","DOIUrl":"https://doi.org/10.1080/04353676.2017.1407219","url":null,"abstract":"ABSTRACT Based on existing meteorological records, increases of annual air temperatures, annual precipitation sums, annual wind speeds, and of the frequencies and intensities of heavy rainfall and storm events in Norway are postulated. From a process-geomorphological point of view it is of growing importance to obtain an improved knowledge of the complex relationships between contemporary geomorphologic processes, vegetation cover and present-day climatic conditions to arrive at more realistic assessments of possible geomorphic effects of ongoing and future climate changes. This study analyzes the morphoclimate of a boreal-oceanic drainage basin system in central Norway and presents aspects of the contemporary wind, air temperature and precipitation regimes that control the type, frequency, intensity and duration of relevant denudational surface processes operating in the area. The work is based on statistical analyses (magnitude-frequency analyses) of existing meteorological data and process-geomorphologic field work conducted over a five-year investigation period (November 2011–October 2016) in the Homla drainage basin (156.3 km2) in central Norway. Due to the distinct characteristics of the present-day morphoclimate, runoff occurs year-round and chemical denudation clearly dominates over mechanical denudation. Mechanical denudation is strongly event-controlled and the highest share of annual fluvial transport occurs in May during the peak of spring snowmelt. Both chemical denudation (12.1 t km−2 yr−1) and mechanical denudation (3.6 t km−2 yr−1) are of low intensity which is explained by the cool climate combined with a nearly closed and continuous vegetation cover, small thicknesses of sedimentary covers, a high weathering resistance of the predominant bedrock and only low topographic relief in the upper parts of the Homla drainage basin. It is expected that the postulated changes of the wind, air temperature and precipitation regimes will lead to increasing chemical and mechanical denudation rates in the study area.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90378954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glacier recession in the Altai Mountains of Mongolia in 1990–2016","authors":"C. Pan, A. Pope, U. Kamp, A. Dashtseren, M. Walther, M. Syromyatina","doi":"10.1080/04353676.2017.1407560","DOIUrl":"https://doi.org/10.1080/04353676.2017.1407560","url":null,"abstract":"ABSTRACT Relatively little is known about glaciers in the continental climates of North Asia and even less is known about the glaciers of the Mongolian Altai. In an attempt to fill this knowledge gap, we present a new satellite-derived glacier inventory for the Altai Mountains of Mongolia, using the recently launched Landat-8 OLI and Sentinel-2A MSI sensors to monitor glacier change from 1990 to 2016. We examine changes in climatic trends and glacier topomorphological parameters in conjunction with glacier fluctuations to determine governing controls over glacier recession in the Altai Mountains. Our glacier mapping results produced 627 debris-free glaciers with an area of 334.0 ± 42.3 km2 as of 2016. These data were made available for download through the Global Land Ice Measurements from Space (GLIMS) initiative. A subsample of 206 glaciers that were mapped in 1990, 2000, 2010, and 2016 revealed that from 1990 to 2016, glacier area reduced by 43% at 6.4 ± 0.4 km2 yr−1. Glacier recession was greatest from 1990 to 2000 at a rate of 10.9 ± 0.8 km2 yr−1, followed by 2010–2016 at 4.4 ± 0.3 km2 yr−1. Rates of glacier recession were significantly correlated with intrinsic glacier parameters, including mean, minimum and range elevations, mean slope and aspect. Furthermore, climate records indicated the warmest summer temperatures occurred during periods of high glacier recession.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87718368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical records of paleocontamination in late pleistocene lake sediments in West Flanders (Belgium)","authors":"A. Andronikov, I. Andronikova, D. Subetto, E. Rudnickaitė","doi":"10.1080/04353676.2017.1408955","DOIUrl":"https://doi.org/10.1080/04353676.2017.1408955","url":null,"abstract":"ABSTRACT Concentrations of trace elements in Late Pleistocene lake sediments from two localities in West Flanders (Belgium) were studied using inductively coupled plasma-mass spectrometry. The studied sediments were deposited during the transition of the Allerød to the Younger Dryas. Trace elements enter lake environments from a variety of sources, but mostly from bedrock weathering in catchments and as wind-blown dust particles. These sources create a natural trace element background in lake sediment records. The concentration and distribution of trace elements across the studied lake sediment sequences display features consistent with inputs of materials other than those from soil or bedrock. Input from volcanic eruptions, biomass burning and meteorite impacts should be considered among the main sources of non-anthropogenic contamination of lake environments.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85079738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controls and implications of source-to-sink environmental fluxes in selected cold climate environments","authors":"A. Beylich, A. Baltakova","doi":"10.1080/04353676.2018.1467529","DOIUrl":"https://doi.org/10.1080/04353676.2018.1467529","url":null,"abstract":"This Thematic Issue on Controls and implications of source-to-sink environmental fluxes in selected cold climate environments produced by the I.A.G./A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) working group (http://www.geomorph.org/sedibud-working-group/) presents a selection of papers that were presented and discussed during the 10th I.A.G./A.I.G. SEDIBUDWorkshop onMonitoring of geomorphological processes in cold environments under climate change held 7– 10 September 2016 in Bansko, Bulgaria. Complex relationships exist between climate, vegetation cover and the dynamics of geomorphological Earth surface systems. Environmental changes have significant impacts on these relationships and on Earth surface system dynamics. The studies presented in this Thematic Issue collectively represent a cross section of latest research activities on drivers and implications of such relationships and environmental fluxes from different cold climate environments. Most of them concern the manifestation of hazardous processes and provide important results from their direct monitoring. The selected work covers cold environments in Norway, Romania and South Africa.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85046306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tree-ring-based reconstruction of high-magnitude snow avalanches in Piatra Craiului Mountains (Southern Carpathians, Romania)","authors":"O. Pop, A. Munteanu, Meseşan Flaviu, I. Gavrilă, C. Timofte, Iulian Holobâcă","doi":"10.1080/04353676.2017.1405715","DOIUrl":"https://doi.org/10.1080/04353676.2017.1405715","url":null,"abstract":"ABSTRACT Tree-ring analyses were applied in this study, in order to document the spatial–temporal distribution of the past snow avalanche activity along two adjacent avalanche paths in Piatra Craiului Mountains (Southern Carpathians, Romania). The dendrogeomorphic reconstruction performed on 235 Picea abies (L.) Karst. trees is based on the analysis of the effects related to the mechanical impact that snow avalanches had on trees, which resulted in growth anomalies (e.g. scars, callus tissues, onset sequences of tangential rows of traumatic resin ducts, compression wood, growth suppression and release). Tree-growth anomalies found in cores and discs led to the determination of 8 avalanche events within path (1), respectively 10 avalanche events within path (2) spanning the 1950–2016 reconstructed period. Within the paths, a minimum frequency of major snow avalanches was determined and their spatial extent was defined for each reconstructed event. The analysis of weather conditions for two of the events documented in archival records and reconstructed by dendrogeomorphic analyses revealed the role of freezing/thawing periods, combined with heavy snowfalls, in triggering major snow avalanches.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80791282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geophysical, topographic and stratigraphic analyses of perialpine kettles and implications for postglacial mire formation","authors":"J. Götz, B. Salcher, R. Starnberger, R. Krisai","doi":"10.1080/04353676.2018.1446638","DOIUrl":"https://doi.org/10.1080/04353676.2018.1446638","url":null,"abstract":"ABSTRACT Kettle holes are common ice decay features in formerly glaciated areas. They are highly variable in size and geometry and may form in a variety of glacial and glaciofluvial landforms. Kettle holes are either dry or exist as wetlands or lakes, only rarely transforming into kettle-hole mires. This study investigates Late Pleistocene kettles in the area of the LGM Salzach Glacier Lobe in the North Alpine Foreland. Kettles are here specifically well preserved and concentrate along the former glacier lobe terminus, where they could develop within large elevated areas protected from pro and postglacial sediment redistribution also showing minor anthropogenic overprint. Highest kettle concentrations were observed within a narrow swath along the distal lobe dominated by terminal moraines, ice wastage and outwash deposits, whereas they are almost absent in the centre of the former glacier lobe. Based on a new dataset on regional kettle distribution and a study of comparable wetland environments, we show that kettle lake formation is a specific but rare phenomenon, which is closely related to the preceding dynamics at the glacier lobe and the glacial depositional environment. By applying geophysical surveys (electrical resistivity tomography, ground-penetrating radar), topographic as well as stratigraphic investigations (DEM analysis, core-drilling and radiocarbon dating), we explore the postglacial evolution of the Jackenmoos kettle and propose a modified model of peat formation in kettle-hole mires, mainly as a function of the centripetal growth of a floating mat covering a central subsurface water body.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2018-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87266475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}