Glaciology Research Papers - Academia.edu (original) (raw)

A model subglacial drainage system, coupled to an ice-dammed reservoir that receives a time-varying meltwater input, is described and analysed. In numerical experiments an ice-marginal lake drains through a subglacial channel, producing... more

A model subglacial drainage system, coupled to an ice-dammed reservoir that receives a time-varying meltwater input, is described and analysed. In numerical experiments an ice-marginal lake drains through a subglacial channel, producing periodic floods, and fills with meltwater at a rate
dependent on air temperature, which varies seasonally with a peak value of Tm. The analysis reveals regions of Tm parameter space corresponding to ‘mode locking’, where flood repeat time is independent of Tm; resonance, where decreasing Tm counter-intuitively increases flood size; and chaotic dynamics,
where flood cycles are sensitive to initial conditions, never repeat and exhibit phase-space mixing. Bifurcations associated with abrupt changes in flood size and timing within the year separate these regions. This is the first time these complex dynamics have been displayed by a glaciohydraulic model
and these findings have implications for our understanding of ice-marginal lakes, moulins and subglacial lakes.

Light absorbing particles (LAPs) can have a significant impact on the albedo of snow. LAPs absorb solar radiation which warms surrounding snow thereby increasing melt or sublimation rates. Historically, LAP concentrations have been... more

Light absorbing particles (LAPs) can have a significant impact on the albedo of snow. LAPs absorb solar radiation which warms surrounding snow thereby increasing melt or sublimation rates. Historically, LAP concentrations have been reported in terms of a mass mixing ratio, typically in nanograms of black carbon per gram of snow. While this representation is convenient for sampling, it can lead to deceptive results if there is significant surface accumulation of LAPs due to snow loss or dry deposition. Here we demonstrate that LAPs concentrated on the snow surface can substantially affect the albedo and typical sampling strategies and reporting protocols can lead to highly erroneous estimates of albedo. Theoretical calculations and measurements both show that the reduction in albedo by LAPs can be twice as strong when particles are concentrated on the surface as opposed to being mixed within the top thin layer of snow. Current commonly used sampling strategies are not sufficient to determine the necessary information to assess the impact of surface LAPs on snowpack albedo. To facilitate more accurate albedo estimates, we propose a new sampling strategy to better characterize LAP distribution in and on snowpacks. Theoretical calculations and experimental measurements show that snowpack albedo can be much better characterized when using the suggested sampling strategy to determine the distribution of LAPs present. 1 Introduction Light absorbing particles on snow have classically been measured and reported in terms of a mass mixing ratio (MMR) of LAPs, for example as nanograms of black carbon (or effective black carbon, eBC, Grenfell et al., 2011) per gram of snow. Sampling strategies can include the collection of snow at specific depths in a snow pit (Doherty et al., 2013), or sections of an ice core (Ginot et al., 2014), or simply surface and sub-surface measurements where the depth of the surface snow sample is loosely defined (Schmitt et al., 2015). The results of these studies are difficult to compare due to the lack of uniformity in snow density and sampling depth.

Гляциология в целом базируется на ложных позициях. Главной ошибкой является утверждение, что ледник может разрушать, поднимать и переносить горные породе. Причем стиль изложения предполагает, что делает он это с легкостью. Производная от... more

Гляциология в целом базируется на ложных позициях. Главной ошибкой является утверждение, что ледник может разрушать, поднимать и переносить горные породе. Причем стиль изложения предполагает, что делает он это с легкостью. Производная от этого является утверждение, что морена является надежным показателем существования ледников. Интересно, что эти утверждения не сопровождаются физическими моделями и расчетами. Все это воспринимают на веру почти двести лет.

Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE/EAGE Reservoir Characterization and Simulation Conference held in Abu Dhabi, UAE, 19–21 October 2009. This paper was selected for... more

Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE/EAGE Reservoir Characterization and Simulation Conference held in Abu Dhabi, UAE, 19–21 October 2009. This paper was selected for presentation by an SPE ...

Time-lapse seismics is the methodology of choice for remotely monitoring changes in oil/gas reservoir depletion, reservoir stimulation or CO 2 sequestration, due to good sensitivity and resolving power at depths up to several kilometres.... more

Time-lapse seismics is the methodology of choice for remotely monitoring changes in oil/gas reservoir depletion, reservoir stimulation or CO 2 sequestration, due to good sensitivity and resolving power at depths up to several kilometres. This method is now routinely applied offshore, however, the use of time-lapse methodology onshore is relatively rare. The main reason for this is the relatively high cost of commercial seismic acquisition on land. A widespread belief of a relatively poor repeatability of land seismic data prevents rapid growth in the number of land time-lapse surveys. Considering that CO 2 sequestration on land is becoming a necessity, there is a great need to evaluate the feasibility of time-lapse seismics for monitoring. Therefore, an understanding of the factors influencing repeatability of land seismics and evaluating limitations of the method is crucially important for its application in many CO 2 sequestration projects. We analyse several repeated 2D and 3D surveys acquired within the Otway CO 2 sequestration pilot project (operated by the Cooperative Research Centre for Greenhouse Technologies, CO2CRC) in Australia, in order to determine the principal limitations of land time-lapse seismic repeatability and investigate the influence of the main factors affecting it. Our findings are that the intrinsic signal-to-noise ratio (S/N, signal to coherent and background noise levels) and the normalized-root-meansquare (NRMS) difference are controlled by the source strength and source type. However, the post-stack S/N ratio and corresponding NRMS residuals are controlled mainly by the data fold. For very high-fold data, the source strength and source type are less critical.

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes (MDGLs) in the recent past have increased the risk of glacier lake outburst floods (GLOF) in the countries of Nepal and Bhutan and... more

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes (MDGLs) in the recent past have increased the risk of glacier lake outburst floods (GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis (LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km 2 , that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and 6800 m above mean sea level (a msl). With a total surface area of 37.9 km 2 , these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.

Hydropower and water resources management are an important issue in most countries of the world, included Switzerland. The scientific community is currently engaged to produce numerical models and simulations which aim at understanding... more

Миссульськие наводнения является одним из важнейших и интереснейших явлений последнего ледникового периода Северной Америки. Его важность обусловлена тем, что впервые гляциологам пришлось признать, что не только лед, но и вода во время... more

Миссульськие наводнения является одним из важнейших и интереснейших явлений последнего ледникового периода Северной Америки. Его важность обусловлена тем, что впервые гляциологам пришлось признать, что не только лед, но и вода во время оледенения могла быть главной силой в перестройке поверхности. Открыл это явление американский геолог J Harlen Bretz фактически сто лет назад. Формирование рельефа, который он подробно изучал в течение многих лет, не имело и не могло иметь другого объяснения, чем работа воды.

The main objective of this work is the estimation of the speed ice flow on the Upsala Glacier using radar images. The Upsala Glacier is one of the temperate glaciers of high scientific interest in the Southern Patagonian Ice Field that... more

Experimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by... more

Experimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by the downward growth of thin dendritic crystals into the supercooled pendant water drop at the tip, and thus the growth is in the crystallographic a-axis direction. The diameter, on the other hand, increases by the freezing of a water film flowing down along the icicle wall. The ratio of measured length-and diameter-growth rates was large, namely 8–32. Both growth rates increased with decreasing temperature and increasing wind speed. The increase in water-supply rate led to the decrease in the length-growth rate but no significant change in the diameter-growth rate. These results could be well described by a numerical model of icicle growth which takes account of the dendritic growth at the tip and the wall and the effective heat transfer within the ...

We describe and delimit with integrative taxonomy the new springtail species Desoria calderonis sp. nov. (Collembola: Isotomidae). This cryophilic species is strictly linked to the supraglacial stony debris of the isolated Calderone... more

We describe and delimit with integrative taxonomy the new springtail species Desoria calderonis sp. nov. (Collembola: Isotomidae). This cryophilic species is strictly linked to the supraglacial stony debris of the isolated Calderone glacier (Central Apennines, Italy), one of the southernmost glaciers of Europe. Desoria calderonis sp. nov. could belong to the nivalis-complex, a group of European mountain species included in the violacea-group. Genetic analysis (COI mtDNA barcoding) confirms the morphological attribution to the genus Desoria Nicolet in Desor, 1841, but highlights that the genus, in its current definition, is polyphyletic. We specify the peculiar micro-habitat preferences and highlight the threat of extinction for this cryophilic species in the context of the ongoing climate change and subsequent risk of complete disappearance of the glacier.

Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier... more

Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the 'calving problem' involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. These include: fracture propagation in response to local stress imbalances in the immediate vicinity of the glacier front; undercutting of the glacier terminus by melting at or below the waterline; and bending at the junction between grounded and buoyant parts of an ice tongue. Calving of projecting, submerged 'ice feet' can be regarded as a third-order process, because it is paced by first- or second-order calving above the waterline. First-order calving can be represented in glacier models using a calving criterion based on crevasse depth, which is a function of longitudinal strain rate. Modelling changes in terminus position and calving rates thus reduces to the problem of determining the ice geometry and velocity distribution. Realistic solutions to the problem of modelling ice flow therefore depend critically on an appropriate choice of sliding law. Models that assume that basal velocities are controlled by basal drag can replicate much of the observed behaviour of calving glaciers with grounded termini, but an important limitation is that they cannot be used to model floating glacier termini or ice shelves. Alternative sliding laws that parameterise drag from the glacier margins provide more flexible and robust ways of representing calving in ice sheet models. Such models can explain a remarkable range of observed phenomena within a simple, unifying framework, including: downglacier increases in velocity and strain rates where basal and/or lateral drag diminishes; flow acceleration in response to thinning through time; the tendency for glaciers to stabilise at 'pinning points' in relatively shallow water or fjord narrowings; the constraints on ice shelf stability; and the contrasts in calving rates between tidewater and freshwater calving glaciers. Many unresolved issues remain, however, including the role played by the removal of backstress in the acceleration of retreating calving glaciers, and the controls on melting at and below the waterline.

The aim of this study was to improve our understanding of Quaternary glaciations in Tasmania, and to assess their climatic significance. During the Quaternary, Tasmania experienced ice cap development in the West Coast Range and Central... more

The aim of this study was to improve our understanding of Quaternary glaciations in Tasmania, and to assess their climatic significance. During the Quaternary, Tasmania experienced ice cap development in the West Coast Range and Central Plateau, with smaller cirque and valley glaciers developing on surrounding mountains. Geomorphic evidence indicates at least four glacial advances occurred. A 500 m resolution, three-dimensional thermomechanical ice-sheet model was used to reconstruct and simulate these glacier fluctuations. The model, while a simplification of reality, provided a framework in which to understand the genesis of contemporary landforms and former glacial climate conditions in Tasmania. Input specifications of basal topography, temperature and precipitation were required, with the latter two interpolated from present-day datasets. Numerous experiments were carried out, involving systematic alterations to temperature and precipitation, basal sliding and atmospheric tempe...

Antarctica is a continent locked in ice, with almost 99.7% of current terrain covered by permanent ice and snow, and clear evidence that, as recently as the Last Glacial Maximum (LGM), ice sheets were both thicker and much more extensive... more

Antarctica is a continent locked in ice, with almost 99.7% of current terrain covered by permanent ice and snow, and clear evidence that, as recently as the Last Glacial Maximum (LGM), ice sheets were both thicker and much more extensive than they are now. Ice sheet modelling of both the LGM and estimated previous ice maxima across the continent give broad support to the concept that most if not all currently ice-free ground would have been overridden during previous glaciations. This has given rise to a widely held perception that all Mesozoic (pre-glacial) terrestrial life of Antarctica was wiped out by successive and deepening glacial events. The implicit conclusion of such destruction is that most, possibly all, contemporary terrestrial life has colonised the continent during subsequent periods of glacial retreat. However, several recently emerged and complementary strands of biological and geological research cannot be reconciled comfortably with the current reconstruction of Antarctic glacial history, and therefore provide a fundamental challenge to the existing paradigms. Here, we summarise and synthesise evidence across these lines of research. The emerging fundamental insights corroborate substantial elements of the contemporary Antarctic terrestrial biota being continuously isolated in situ on a multi-million year, even pre-Gondwana break-up timescale. This new and complex terrestrial Antarctic biogeography parallels recent work suggesting greater regionalisation and evolutionary isolation than previously suspected in the circum-Antarctic marine fauna. These findings both require the adoption of a new biological paradigm within Antarctica and challenge current understanding of Antarctic glacial history. This has major implications for our understanding of the key role of Antarctica in the Earth System.

The melting of ice and the subsequent production of regelation ice from the melt water in a large-scale closed system beneath sub-polar and polar glaciers produces progressive fractionation between the melt water and the regelation ice... more

The melting of ice and the subsequent production of regelation ice from the melt water in a large-scale closed system beneath sub-polar and polar glaciers produces progressive fractionation between the melt water and the regelation ice derived from it. A theory is developed which predicts the change of isotopic composition in regelation ice in a subglacial zone of freezing and in the water from which it is derived. The theory is tested against data from the Byrd Station bore hole in West Antarctica, and applied to explain features of the isotopic composition in several other glaciers where thick sequences of regelation ice have formed. The principal conclusions are: 1. Basal isotopic profiles can be used to reconstruct important features of a glacier’s hydrological system. 2. Isotopic profiles in basal regelation ice do not simply reflect isotopic characteristics of ancient atmospheres but also, by using the theory, some of the isotopic characteristics of the normal glacier ice whic...

Holocene glacier fluctuations in College Fjord in south-central Alaska provide an integrated proxy record of climatic and related environmental changes through this critical geologic epoch. During the early Holocene around 10,000 yr BP,... more

Holocene glacier fluctuations in College Fjord in south-central Alaska provide an integrated proxy record of climatic and related environmental changes through this critical geologic epoch. During the early Holocene around 10,000 yr BP, ice was receding from lower Port Wells but was still present in College Fjord. With the beginning of the Holocene Climatic Optimum, recession increased and the ice front reached the Golden Moraine site 1 by 7680 cal yr BP, starting its long early to middle Holocene retreat to the head of tidewater. An ice-free fjord existed between 7680 cal yr BP and about 5190 yr BP. A middle Holocene advance started between approximately 5190 and 4470 yr BP with ice arriving at the mouth of the fjord before 2470 cal yr BP. The late Holocene was characterized by various standstills and minor readvance positions as the glacier fell back and by significant Little Ice Age expansions and retreats of individual glaciers present in the fjord. During the late Holocene, the glacier built four large and distinctive moraines all representative of at least four standstill positions of College Fjord Glacier before 2470, 2060, 1330, and approximately 1120 cal yr BP.

A NEW DISCOVERY, CALLED TODAY "THE ICE FLOW THEORY."

Krasno polje is one of the less typical karst poljes within the Dinaric Mountains. It is situated within Velebit Mountain. Our research utilized morphographic, morphostructural and morphometric analysis of the polje to present its mor... more

Krasno polje is one of the less typical karst poljes within the Dinaric Mountains. It is situated within Velebit Mountain. Our research utilized morphographic, morphostructural and morphometric analysis of the polje to present its mor phogenetic characteristics. It is completely filled with gravel and lacking any surface flows. Slopes above the polje were severely altered by glacial action during the colder periods of the Pleistocene. As a result, proglacial fans filled the karst depression, creating a piedmont type polje. Glacial evidence suggests that there were at least two separate phases of in tense proglacial deposition within the polje.

The Upper Durance catchment is an area prone to rock-slope failures. Such failures reflect the combination of high relief, lithostructural controls and paraglacial stress release. The aim of this study is to determine the role of... more

The Upper Durance catchment is an area prone to rock-slope failures. Such failures reflect the combination of high relief, lithostructural controls and paraglacial stress release. The aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure. Former dimensions of the Durance glacier are reconstructed, then combined with Digital Elevation Model data in a raster Geographic Information System to quantify the spatial pattern of stresses associated with glacial loading at the Last Glacial Maximum. Preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses. Focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated. Description of slope failure runout deposits allows reconstruction of the nature of slope failure. Surface exposure dates based on concentration of cosmogenic 10 Be allows the timing of both deglaciation and that of post-glacial rock-slope failures to be established. It is shown that rock-slope failures are concentrated on lower valley-side slopes within the area occupied by ice at the Last Glacial Maximum, and that their locations coincide with zones of inferred high glacial loading stress, consistent with interpretation of both bedrock disruption and large-scale rock-slope failures as paraglacial phenomena induced by stress release following deglaciation. Timing of initial rock avalanche runout deposition at one site is consistent with this conclusion, though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release.

The designations employed and the presentation of material throughout the publication do not imply the expression of any opinion whatsoever on the part of IAHS concerning the legal status of any country, territory, city or area or of its... more

The designations employed and the presentation of material throughout the publication do not imply the expression of any opinion whatsoever on the part of IAHS concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Computerized evaluation of Vibroseis similarity test data is the logical consequence of the increasing quality requirements for signal reproducibility and for synchronization of vibrators. The differences in start time and phase as well... more

Computerized evaluation of Vibroseis similarity test data is the logical consequence of the increasing quality requirements for signal reproducibility and for synchronization of vibrators. The differences in start time and phase as well as an indication of local phasing problems between any two Vibroseis signals can be obtained from an analysis of the difference of their respective phase spectra. This method appears to be accurate and stable with respect to harmonics which usually plague the signals from transducers monitoring the motion of the vibrators'base plates.

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and... more

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.

Timely for a "Lexicon for an Anthropocene Yet Unseen"

Investigations have been made of the geomorphology, internal structure, and till fabric of small drumlins in a drumlin field exposed in front of the retreating northern part of Mýrdalsjökull, Iceland. The drumlins either comprise... more

Investigations have been made of the geomorphology, internal structure, and till fabric of small drumlins in a drumlin field exposed in front of the retreating northern part of Mýrdalsjökull, Iceland. The drumlins either comprise irregular drumlin complexes or they show clearly the shape of typical drumlins with their highest points at the up-glacier ends of streamlined hills. The core of each drumlin consists either of undisturbed glacio-fluvial deposits or glacio-dynamically deformed drift. The distribution of the first type often has a characteristic en échelon arrangement, similar to the interstream areas in the upper reaches of outwash fans. The second type forms a pattern with a predominant trend conforming to the glacier margin; this type is superimposed on overridden ice-margin push-moraine ridges. It is shown that the material in the drumlin cores is only slightly eroded by the glacier that formed the drumlins. The core is mantled by subglacial lodgement till about 0.1–1.5 ...

Seu conteúdo foi revisado pelo Comitê Técnico do IV SimBGf, mas não necessariamente representa a opinião da SBGf ou de seus associados. É proibida a reprodução total ou parcial deste material para propósitos comerciais sem prévia... more

Seu conteúdo foi revisado pelo Comitê Técnico do IV SimBGf, mas não necessariamente representa a opinião da SBGf ou de seus associados. É proibida a reprodução total ou parcial deste material para propósitos comerciais sem prévia autorização da SBGf.

La mayor parte de la población de Perú se concentra en ciudades localizadas en la estrecha franja comprendida entre la costa del Océano Pacífico y los Andes Centrales. Se trata de una de las regiones más áridas de la Tierra, donde la... more

La mayor parte de la población de Perú se concentra en ciudades localizadas en la estrecha franja comprendida entre la costa del Océano Pacífico y los Andes Centrales. Se trata de una de las regiones más áridas de la Tierra, donde la precipitación total anual apenas alcanza unas decenas de mm. Por ese motivo las reservas hídricas de la población y sus actividades económicas dependen en gran medida de los glaciares que se conservan en la cordillera. Esas masas de hielo forman parte de la criosfera, junto con la nieve, los glaciares rocosos y las capas de suelo helado (permafrost), que también están adquiriendo gran importancia como reservas de agua debido a la marcada tendencia a la reducción de la superficie y el volumen de los glaciares observada durante las últimas décadas. El proceso de deglaciación implica además un incremento de los peligros geológicos asociados a la criosfera, como aludes, avalanchas y otros tipos de movimientos en masa. El riesgo es mayor si cabe en las vertientes de la cordillera como consecuencia de su fuerte desnivel. En ese contexto la Autoridad Nacional del Agua (ANA); el Instituto Geológico Minero y Metalúrgico (INGEMMET); el Grupo de Investigación en Geografía Física de Alta Montaña de la Universidad Complutense de Madrid (GFAM) y la ONG Guías de Espeleología y Montaña (GEM), con el auspicio de la Organización de las Naciones Unidas para la Educación, la Ciencia y la Cultura (UNESCO), han acordado impulsar un proyecto denominado CRYOPERU, con dos metas principales: 1) Contribuir a la comprensión de los efectos del cambio climático en la criosfera de los Andes Centrales, en relación con dos problemas que afectan a Perú: la reducción de las reservas hídricas sólidas y el incremento de los peligros geológicos asociados al proceso de deglaciación. 2) Proporcionar instrumentos de análisis a las instituciones que deben planificar y ejecutar las políticas de adaptación y mitigación de la sociedad a los efectos del cambio climático. Para alcanzar los objetivos previstos el proyecto analizará 10 geoindicadores del cambio climático y 4 geoindicadores de peligros geológicos en 8 áreas de estudio distribuidas de norte a sur de la cordillera occidental y la cordillera oriental de los Andes Centrales. Se ha previsto el desarrollo de un software para automatizar, sistematizar y recopilar los resultados. El software será la plataforma tecnológica online de un Observatorio de la Criosfera.

Необхідність написання передмови до дисертації робота над якою була завершена ще у 2010 році пов’язана з кількома причинами. Головною є та обставина, що у той час, на підставі аналізу змін будови долини середньої течії Дніпра, було... more

Необхідність написання передмови до дисертації робота над якою була завершена ще у 2010 році пов’язана з кількома причинами. Головною є та обставина, що у той час, на підставі аналізу змін будови долини середньої течії Дніпра, було зрозуміло, що перебудова відбулася в наслідок кількох потужних катастрофічних післяльодовикових потоків. Цій проблемі було присвячено досить значний об’єм роботи. Десь біля 60 сторінок.

Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial... more

Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial conditions that favour or suppress cavity formation (ice velocity, ice thickness, and water pressure) are thought to favour plucking or abrasion, respectively.

На сайті Academia біля п’яти років розміщена робота "Льодовики, давня людина та палеогеографія України", а також її версія "Давня людина і палеогеографічні умови України" (З книжки: "Природна та етнокультурна спадщина України"). За цей... more

На сайті Academia біля п’яти років розміщена робота "Льодовики, давня людина та палеогеографія України", а також її версія "Давня людина і палеогеографічні умови України" (З книжки: "Природна та етнокультурна спадщина України"). За цей час кількість читачів подолала 1000. Ці роботи були написані по матеріалам до 2010 року. Читачі, напевно, помітили, що вони базуються на принципово інших підходах до оцінки подій, які мали місце на території України, ніж в офіційних виданнях. Перш за все це стосується зледеніння.
Коли писалися роботи, тоді вже була впевненість, що Україна не зазнала зледеніння. З одного боку, це базувалася на фактичному матеріалі, а з іншого на результатами фізичного аналізу природних процесів. Але, у той час ще не було загальної фізичної оцінки. Зараз вона завершена і треба сказати, що зараз "впевненість" підкріплена "доказами". А це єдиний критерій для визначення реальності подій. Не стандартна для сучасної науки фраза: "Як вважає якийсь авторитет….", а реальна фізика. Далі буде показане, як народжувалися без знання об’єкту досліджень "наукові" теорії, які можна оцінювати, як дитячі казки. На жаль наука в Україні не тільки залишилася на тому рівні, але можна констатувати, що її вже просто немає.
Тому для узгодження й кращого розуміння попередніх текстів було вирішено додати до них результати теоретичних досліджень. Тут вони вміщені не повністю, а тільки в об’ємі, який стосується нашої території та подій, що тут відбувалися.

This work proposes a 2.5D modeling for a section crossing a segment of the Transbrasiliano Lineament in the southern part of Parnaiba Basin, NE Brazil-based on joint inversion of magnetic and gravimetric data. This study points out that... more

This work proposes a 2.5D modeling for a section crossing a segment of the Transbrasiliano Lineament in the southern part of Parnaiba Basin, NE Brazil-based on joint inversion of magnetic and gravimetric data. This study points out that the thickness of the sedimentary cover is related to tectonic features such as graben and horsts. Euler deconvolution technique was used in this work aiming to reduce ambiguities of the model as well as to contribute for a better quantification of anomalous source depths. A previous qualitative analysis was necessary to obtain an understanding of different types of sources that might be responsible for magnetic and gravimetric signatures in the area. This analysis was important to a better interpretation of the anomalous sources as long as not all given solutions offered by the Euler technique are those that are aimed to be analyzed.

Выполненные ранее исследования особенностей распространения Полесских озер, послеледниковых озер Северной Америки и современных приледниковых озер Гренландии показали, что в основе механизма их формирования лежат вихревые системы,... more

Выполненные ранее исследования особенностей распространения Полесских озер, послеледниковых озер Северной Америки и современных приледниковых озер Гренландии показали, что в основе механизма их формирования лежат вихревые системы, возникающие в краевых частях ледников или при поступлении значительного количества талой воды на поверхность промерзших приледниковых озер. После того, как в ходе воспоминаний с коллегами, о проблемах советской геоморфологии, в которые были упомянуты и Чарские пески, аналогичный поход был имплементирован и по отношению к ним. Результаты исследований были такими же, как и в предыдущих работах. Источником песка стали твердые горные породы, которые были перемолоты вихревыми системами в условиях горного озера, которое во время деградации горных ледников превратилось в ледоем.
Естественно, что следующим объектом исследований автоматически стали тукуланы Якутии. Они, как и Чарские пески, песчаные арены Аляски и Канады, до сегодняшнего дня остаются необъяснимыми природными феноменами. В среде естествоиспытателей обеих континентов издавна прижилось мнение об их эоловом происхождении. Всех эта версия устраивала, несмотря на то, что для ее подтверждения не был выполнен элементарный анализ климатических условий этих территорий на предмет их соответствия физическим условиям, при которых начинается эоловая активность. Наблюдения, естественно, были. Ими фиксировались перемещение песчаного материала в современных условиях. По наличию погребенных почв и органики выделялись периоды активизации эоловой деятельности. При этом упускались из виду очень важные аспекты.

It is no longer possible to maintain that the ancient economy completely escapes any possibility of quantification over the long run. There are good indicators to measure development of the economy in general: atmospheric pollution by... more

It is no longer possible to maintain that the ancient economy completely escapes any possibility of quantification over the long run. There are good indicators to measure development of the economy in general: atmospheric pollution by lead for the production of silver coinages, copper for the bronze, and shipwrecks for levels of trade. The convergence of these graphs clarifies an increased activity during the last centuries BC and the first three centuries AD. Of the three, the wrecks is the most spectacular with its peak in the period 200 BC-AD 200. This kind of periodization also seems to agree best with monetary affairs.

Случилось так, что после публикации в Интернете первой версии этой статьи в ходе короткой дискуссии с коллегой, главным вопросом была проблема профессиональной оценки. Возражение моего коллеги было следующим: «Я закончил гидрографию, и... more

Случилось так, что после публикации в Интернете первой версии этой статьи в ходе короткой дискуссии с коллегой, главным вопросом была проблема профессиональной оценки. Возражение моего коллеги было следующим: «Я закончил гидрографию, и опубликованная работа охватывает более широкий круг проблем. Большинство из них я знаю только в общих чертах. Как я могу оценить результаты в целом?» Мое возражение было коротким, но оно Была сосредоточена на сущности исследования. Физическая география изучает природу и процессы, которые постоянно изменяют Землю, особенно ее рельеф. Все естественные процессы основаны на физических законах, особенно на механике, поэтому они являются производными от законов физики. Таким образом, понимание «географических законов» требует знания физики, особенно механики. Этот ответ был упрощен. Необходимы также некоторые знания о электричестве и магнетизм.
Основной вывод, вытекающий из этого подхода, очень категоричен. Физическая география в ее нынешнем виде - это не наука. Сегодня это коллекция догадок, идей, догм и тому подобного. Напоминается, что физическая география в прошлом была отраслью физики. Отделенная от физики, география потеряла научную основу и превратилась в псевдонауку. В действительности для понимания основных процессов и явлений нам нужны знания только элементарной физики. Остальная часть, включая географическую терминологию, является мусором. Каждый географический термин можно объяснить повседневным языком. Но интересно, что это, к сожалению, даже физика не понимает.

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design.... more

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design. The ability of GPS geodesy to estimate 3D positions with millimeter-level precision with respect to a global terrestrial reference frame has contributed to significant advances in geophysics, seismology, atmospheric science, hydrology, and natural hazard science. Monitoring the changes in the positions or trajectories of GPS instruments on the Earth's land and water surfaces, in the atmosphere, or in space, is important for both theory and applications, from an improved understanding of tectonic and magmatic processes to developing systems for mitigating the impact of natural hazards on society and the environment. Besides accurate positioning, all disturbances in the propagation of the transmitted GPS radio signals from satellite to receiver are mined for information, from troposphere and ionosphere delays for weather, climate, and natural hazard applications, to disturbances in the signals due to multipath reflections from the solid ground, water, and ice for environmental applications. We review the relevant concepts of geodetic theory, data analysis, and physical modeling for a myriad of processes at multiple spatial and temporal scales, and discuss the extensive global infrastructure that has been built to support GPS geodesy consisting of thousands of continuously operating stations. We also discuss the integration of heterogeneous and complementary data sets from geodesy, seismology, and geology, focusing on crustal deformation applications and early warning systems for natural hazards.

Presently, methods for surveying, at high resolution, complex landforms and landscapes are accompanied by high start-up and data acquisition costs. In addition, issues of portability may be introduced given the relative remoteness and... more

Presently, methods for surveying, at high resolution, complex landforms and landscapes are accompanied by high start-up and data acquisition costs. In addition, issues of portability may be introduced given the relative remoteness and inaccessibility of many field sites, particularly in high-mountain regions.

The relationship between climate change at the Pleistocene-Holocene Boundary (ca. 12,600-10,200 cal B.P.) and cultural responses to attendant shifts in the environment remains a vexing issue for archaeologists. This study compiles and... more

The relationship between climate change at the Pleistocene-Holocene Boundary (ca. 12,600-10,200 cal B.P.) and cultural responses to attendant shifts in the environment remains a vexing issue for archaeologists. This study compiles and analyzes glacial, palynological, faunal, and stratigraphic/geomorphological proxy datasets for climate change in the Pacific Northwest of North America and compares them to the coeval archaeological record. The primary purpose of this exercise is to consider the potential ways in which climate change at the Pleistocene-Holocene Boundary affected cultural development for Late Paleoindian-Early Archaic peoples in the Pacific Northwest. Results indicate that climatic and environmental change at this interval was rapid or abrupt, and of a magnitude that likely produced varying adaptational responses by peoples of different cultural traditions who appear across the region at this period. Transformations in tools and technology, shifts in dietary habits, migration and regionalization, and trade intensification are all elements of Late Paleoindian-Early Archaic cultural responses to rapid climate change.

Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these... more

Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these trajectories provides a simple descriptive tool that complements and extends conventional sequence stratigraphic methods and models. Trajectory analysis offers four advantages over a sequence stratigraphic interpretation based on systems tracts: (1) each genetically related advance or retreat of a shoreline or shelf edge is viewed in the context of a continuously evolving depositional system, rather than as several discrete systems tracts; (2) subtle changes in depositional response (e.g. within systems tracts) can be identified and honoured; (3) trajectory analysis does not anticipate the succession of depositional events implied by systems-tract models; and (4) the descriptive emphasis of trajectory analysis does not involve any a priori assumptions about the type or nature of the mechanisms that drive sequence development. These four points allow the level of detail in a trajectory-based interpretation to be directly tailored to the available data, such that the interpretation may be qualitative or quantitative in two or three dimensions. Four classes of shoreline trajectory are recognized: ascending regressive, descending regressive, transgressive and stationary (i.e. nonmigratory). Ascending regressive and high-angle (accretionary) transgressive trajectories are associated with expanded facies belt thicknesses, the absence of laterally extensive erosional surfaces, and relatively high preservation of the shoreline depositional system. In contrast, descending regressive and low-angle (nonaccretionary) transgressive trajectories are associated with foreshortened and/or missing facies belts, the presence of laterally extensive erosional surfaces, and relatively low preservation of the shoreline depositional system. Stationary trajectories record shorelines positioned at a steeply sloping shelf edge, with accompanying bypass of sediment to the basin floor. Shelf-edge trajectories represent larger spatial and temporal scales than shoreline trajectories, and they can be subdivided into ascending, descending and stationary (i.e. nonmigratory) classes. Ascending trajectories are associated with a relatively large number and thickness of shoreline tongues (parasequences), the absence of laterally extensive erosional surfaces on the shelf, and relatively low sediment supply to the basin floor. Descending trajectories are associated with a few, thin shoreline tongues, the presence of laterally extensive erosional surfaces on the shelf, and high sediment supply to basin-floor fan systems. Stationary trajectories record near-total bypass of sediment across the shelf and mass transfer to the basin floor.

A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on 1) mapping and dating moraines defined... more

A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on 1) mapping and dating moraines defined by 14 C, TCN, OSL, lichenometry and tree rings (discontinuous records/time series), and 2) sediments from proglacial lakes and speleothems (continuous records/ time series). Using 189 continuous and discontinuous time series, the long-term trends and centennial fluctuations of glaciers were compared to trends in the recession of Northern and mountain tree lines, and with orbital, solar and volcanic studies to examine the likely forcing factors that drove the changes recorded. A general trend of increasing glacier size from the earlyemid Holocene, to the late

In response to climatic change, the size and number of moraine-dammed supraglacial and proglacial lake systems have increased dramatically in recent decades. Given an appropriate trigger, the natural moraine dams that impound these... more

In response to climatic change, the size and number of moraine-dammed supraglacial and proglacial lake systems have increased dramatically in recent decades. Given an appropriate trigger, the natural moraine dams that impound these proglacial lakes are breached, producing catastrophic Glacial Lake Outburst Floods (GLOFs). These floods are highly complex phenomena, with flood characteristics controlled, in the first instance, by the style of breach formation. Downstream, GLOFs typically exhibit transient, often non-Newtonian fluid dynamics as a result of high rates of sediment entrainment from the dam structure and channel boundaries. Combined, these characteristics introduce numerous modelling challenges. In this review, the historical, contemporary and emerging approaches available to model the individual stages, or components, of a GLOF event are introduced and discussed. A number of methods exist to model the stages of a GLOF event. Dam-breach models can be categorised as being empirical, analytical or numerical in nature, with each method having significant advantages and shortcomings. Empirical relationships that produce estimates of peak discharge and time to peak are straightforward to implement, but the applicability of these models is often limited by the nature of the case study data from which they are derived. Furthermore, empirical models neglect the inclusion of basic hydraulic principles that describe the mechanics of breach formation. Analytical or parametric models simulate breach development using simplified versions of the physically based equations that describe breach enlargement, whilst complex, physically-based codes represent the state-of-the-art in numerical dam-breach modelling. To date, few of the latter have been applied to investigate the moraine-dam failure problem. Despite significant advances in the physical complexity and availability of higher-order hydrodynamic solvers, the majority of published accounts that have attempted to reconstruct or predict GLOF characteristics have been limited, often by necessity, to the use of relatively simplistic models. This is in part attributable to the unavailability of terrain models of many high-mountain catchments at the fine spatial resolutions required for the effective application of numerically-sophisticated codes, and their proprietary (and often cost-prohibitive) nature. However, advanced models are experiencing increasing use in the glacial hazards literature. In particular, the suitability of emerging mesh-free, particle-based methods for simulating dam-breach and GLOF routing may represent a solution to many of the challenges associated with modelling this complex phenomenon. Sources of uncertainty in the GLOF modelling chain have been identified by various workers. However, to date their significance for the robustness of reconstructive and predictive modelling efforts have been largely unexplored and quantified in detail. These sources include the geometric and material characterisation of moraine dam complexes, including lake bathymetry and the presence and extent of buried ice, initial conditions (freeboard, precise spillway dimensions), spatial discretisation of the down-valley domain, hydrodynamic model dimensionality and the dynamic coupling of successive components in the GLOF model cascade.