Glaciology

DEMs (Digital Elevation Model) generated with different remote sensing techniques and technologies. DEMs are used to determine the changes of vegetation in forests depending on topographical factors. The accuracy of DEMs has a major impact on the planning and management of forests. In this study, the accuracy of two different DEM data sources, which are frequently used in the modeling of topographic changes in large field studies in forestry, was compared with the LiDAR-based DEM dataset on a forest site. In this context, three different DEM source were used. One of them was the 10 m interval contour lines of 1:25,000 scale aerial photogrammetry based standard topographical maps which are produced by National General Directorate of Mapping. Topomap contour lines are transformed to grid based DEMs by using TIN and ANUDEM based approaches at 2.5, 5, 10 and 30 m resolutions. The other data was ASTER GDEM (1 arc-second ASTER GDEM Version 2, approximately 30 m resolution). The final and reference data is the LiDAR based, 0.25 m resolution DEM. In total, 33 DEM datasets are compared with the LiDAR-based DEM dataset. For these data sets, five difference metrics were calculated: pixel based difference models, the areal and volumetric difference of surface models, the areal difference of slope classes and the areal difference of aspect classes. According to the results of the analysis, the resolution, according to the topographic characteristics of the area and selected interpolation approaches has an effect on DEM modeling and DEM -derived metrics. In addition, the forest structure has a major impact on the accuracy of ASTER GDEM data.

The 10 Be exposure age method was applied to 21 samples of crystalline rocks from cirques, roches moutonnées, tors and glacial sediments in two valleys of the Giant Mountains in the Bohemian Massif: the Obří důl and the Labský důl Valleys. Geomorphological evidence combined with 10 Be dating shows that deglaciation occurred between (23.2 ± 3.8) ( 10 Be) ka and (8.0 ± 1.5) ( 10 Be) ka. Permanent ice and firn fields were still present in the upper parts of cirques and on plateaus up to around 3 -4 thousand years ago.

The terrestrial topography is controlled by combined actions of both internal (volcanic and tectonic activities) and external processes (erosion and weathering). Volcanic and tectonic are responsible for the relief building by accumulation, exhumation and uplift, ...

Presented in this paper is an analytic approximation to the thermal-fluid problem involving mixed convective heat transfer from a rotating isothermal cylinder placed in a non-uniform stream shear flow. The approximation is obtained using a series expansion of the scaled boundary layer equations in terms of an appropriate boundary layer variable. The resulting approximation is valid both for small time and for moderate and large times for which the Reynolds number of the flow is sufficiently large.

This comprehensive analysis presents complete mathematical derivations demonstrating that the confirmed 24-hour polar sun phenomenon violates energy conservation by infinite factors. Through exhaustive calculations incorporating every known correction factor-maximum albedo (95%), Beer-Lambert atmospheric absorption, elevation effects at 2,835m, minimum sun angles, spectral dependencies, angular variations, cloud cover, wind effects, ocean circulation, and 47 additional examined mechanisms-we prove that even the most conservative calculations predict 0.59-27.54 meters of Antarctic ice melting annually versus essentially zero observed. Temperature predictions yield +64°C expected versus-57°C observed, a 121°C error. We provide complete step-by-step derivations for every calculation, examine and mathematically refute all proposed explanations, and demonstrate that no combination of physical mechanisms can resolve these infinite-factor violations of thermodynamic laws. The December 2024 Final Experiment's confirmation of 24-hour sun paradoxically strengthens these impossibilities.

Using an ensemble of close-and long-range remote sensing, lake bathymetry and regional meteorological data, we present a detailed assessment of the geometric changes of El Morado Glacier in the Central Andes of Chile and its adjacent proglacial lake between 1932 and 2019. Overall, the results revealed a period of marked glacier down wasting, with a mean geodetic glacier mass balance of -0.39 ± 0.15 m w.e.a -1 observed for the entire glacier between 1955 and 2015 with an area loss of 40% between 1955 and 2019. We estimate an ice elevation change of -1.00 ± 0.17 m a -1 for the glacier tongue between 1932 and 2019. The increase in the ice thinning rates and area loss during the last decade is coincident with the severe drought in this region (2010-present), which our minimal surface mass-balance model is able to reproduce. As a result of the glacier changes observed, the proglacial lake increased in area substantially between 1955 and 2019, with bathymetry data suggesting a water volume of 3.6 million m 3 in 2017. This study highlights the need for further monitoring of glacierised areas in the Central Andes. Such efforts would facilitate a better understanding of the downstream impacts of glacier downwasting.

Mountain regions have experienced above-average warming in the 20th century and this trend is likely to continue. These accelerated temperature changes in alpine areas are causing reduced snowfall and changes in the timing of snowfall and melt. Snow is a critical component of alpine areas - it drives hibernation of animals, determines the length of the growing season for plants and the soil microbial composition. Thus, changes in snow patterns in mountain areas can have serious ecological consequences. Here we use 35 years of Landsat satellite images to study snow changes in the Mocho-Choshuenco Volcano in the Southern Andes of Chile. Landsat images have 30 m pixel resolution and a revisit period of 16 days. We calculated the total snow area in cloud-free Landsat scenes and the snow frequency per pixel, here called “snow persistence” for different periods and seasons. Permanent snow cover in summer was stable over a period of 30 years and decreased below 20 km2 from 2014 onward at m...

After eight years of the first distribution of the user's manual of the Seismic Unix (SU) package, it is yet a challenge to execute some seismic processing SU scripts, especially for inexperienced users. Up to now there are few friendly Graphical User Interfaces (GUI) for the SU package, namely Tksu, iSU and GêBR. In order to obtain a more robust and flexible way to work with the SU package, we present a new graphical user interface written in the Java programming language, which can be used under any operating system, the so-called BOTOSEIS. It is adequate to be used both as a production or as interactive development environment, by creating and managing projects, lines and flowcharts of seismic data processing. It is also possible to add SU based softwares, interactively, without knowledge about any programming language. The BOTOSEIS platform is structured by modules, which can be a single application or a combination of SU programs to produce a more complex result, e.g., iVIEW, iVELAN and iNIP-PICKING. The first is a GUI used for data visualization, the second is an important interactive tool for velocity analysis fitted for production environments, and the last is a software for data picking in the zero-offset seismic section that is fundamental for traveltime inversion methods.

using a narrow-beam upward-looking sonar. The I 400 km profile consisted of three legs, of which the long south-north and east-west legs intersected near the Caribou camp of the AIDJEX experiment. A statistical analysis was carried out over contiguous 50 km sections to yield probability-density functions of the drafts of ice and of level ice, the distributions of keel spacings and drafts, and the frequencies and widths of leads. Two distinct types of ice cover were found in the profile. The first, nearest the coast in the south and west of the experimental area, consisted of heavily ridged ice with mean drafts of up to 5. I m. The rest of the track (I 200 km) consisted of a homogeneous ice cover with a mean draft of 3.7 m. The percentage of thin ice varied greatly from section to section, with a range of 0.4 to 12.3% for ice of 0-1 m draft. Level ice, defined as ice with a local gradient of less than I in 40, made up 56% of the homogeneous cover, with a preferred draft of2.7 to 2.9 m. Keel spacings obeyed a negative exponential distribution, with a deficit at small spacings due to a keel shadowing effect and a surfeit at very large spacings due to the contribution of polynyas. The draft distribution of keels was a negative exponential of form P (h) dh = B exp ( -bh) dh, with Band b as parameters. This differs from the distribution of Hibler and others (1972), probably because the narrow beam records a complex structure for every keel. The homogeneous cover had a lower keel frequency and mean draft than the ice nearest the coast. Maximum keel draft was 31.12 m. The average separation of leads was 2 12 m, with almost all leads being less than 50 m in width. REsuME.

During June-July 1985 ice thickness data from upward-looking sonar were obtained by a British submarine in the Greenland Sea, the Fram Strait, and northward into the Eurasian Basin of the Arctic Ocean. A preliminary analysis of the data shows that the mean ice thickness in a test area of the Trans Polar Drift Stream is almost identical to values found during a late winter cruise in 1979 and an autumn cruise in 1976. The data show a radical change in ice properties between the marginal ice zone of the Fram Strait and the central Arctic Basin, with more pressure ridges and fewer leads in the interior zone.

During late winter 2007, coincident measurements of sea ice were collected using various sensors at an ice camp in the Beaufort Sea, Canadian Arctic. Analysis of the archived data provides new insight into sea-ice isostasy and its related R-factor through case studies at three scales using different combinations of snow and ice thickness components. At the smallest scale (<1 m; point scale), isostasy is not expected, so we calculate a residual and define this as Ж (‘zjey’) to describe vertical displacement due to deformation. From 1 to 10 m length scales, we explore traditional isostasy and identify a specific sequence of thickness calculations which minimize freeboard and elevation uncertainty. An effective solution exists when the R-factor is allowed to vary: ranging from 2 to 12, with mean of 5.17, mode of 5.88 and skewed distribution. At regional scales, underwater, airborne and spaceborne platforms are always missing thickness variables from either above or below sea level. ...

The proportions of sand and mud that make up a river-dominated delta strongly determine its topset morphology, which in turn controls its internal facies and clinoforms. These relationships allow one to predict the stratigraphy of a delta from the character of its topset or reconstruct its planform from measures of clinoform geometry. We used Delft3D to simulate nine self-formed deltas having different sediment loads and critical shear stresses required for re-entrainment of mud. The deltas prograded into a shallow basin absent of waves, tides, Coriolis forcing, and buoyancy. Model results indicate that sand-dominated deltas are more fan-shaped and muddominated deltas are more bird's foot in planform because the sand-dominated deltas have more active distributaries and a smaller variance of topset elevations, and thereby experience more equitable distribution of sediment to their perimeters. This results in a larger proportion of channel facies and autogenic parasequences in sand-dominated deltas, and more uniformlydistributed clinoform dip directions, steeper dips, and greater clinoform concavity. These conclusions are consistent with data collected from the Goose River Delta, a coarse-grained fan delta prograding into Goose Bay, Labrador, Canada. These results allow a re-interpretation of the Kf-1 parasequence set of the Cretaceous Last Chance Delta, a unit of the Ferron Sandstone near Emery, UT. Inversion of Ferron grain size data, clinoform dips, clinoform concavity, and variance of dip directions suggests that the Kf-1 Last Chance Delta was more fan-delta than bird's foot, and therefore more consistent with ) than Gardner (1995a and . It likely possessed numerous distributaries with at least five orders of bifurcation. creative scientist. Thank you for the opportunity. Thank you for teaching me how to think and how to approach problems. Thank you for being a mentor and a true friend.

The Northern Sabah Province, which includes the Kudat Peninsula, exhibits a complex structural style. Offshore, NE-striking structural grain changes sharply to E-striking. The E-striking structural grain changes further to SE-striking onshore Kudat Peninsula. A better understanding of the geological structures onshore Kudat Peninsula can benefit hydrocarbon exploration activities offshore. Kudat Peninsula, consisting of sedimentary and ophiolitic igneous rocks experienced polyphase deformation. Folds trending approximately NW -SE are refolded along NNE-SSW trend. The polyphase deformation produced different structural pattern on three major imbricate thrust slices located at the northern, middle and southern part of the peninsula. A major fault zone, characterised by the presence of a melange deposit, separates the northern and middle thrust slices. The northern thrust slice shows a huge drag fold plunging steeply to the southeast. The middle thrust slice shows wavy fold pattern whereas the southern thrust slice shows a nappe-like fold pattern.

As urban development and population growth accelerate, more tunnel construction in seismic zones has been planned. A tunnel's behaviour under earthquake loading must be assessed using proper techniques, in which field tests must evaluate these techniques. However, the field measurements of actual tunnel responses during earthquakes are rare. Centrifuge tests, for example, may be modelled in laboratory settings to simulate the actual tunnel on a much smaller scale. These tests can provide valuable information on how tunnels respond to seismic events and represent a valuable reference for calibrating numerical approaches. Four sets of centrifuge experiments were conducted under the supervision of the ReLUIS research project at the Cambridge University engineering department. This project aimed to develop seismic design procedures through experimental validations of computational methods. The present study aims to numerically model the two series of centrifuge tests under 2D plane-strain conditions on the model scale. A hardening soil model with a small-strain stiffness overlay is implemented to calibrate the Leighton Buzzard sand characteristics. Detailed inspections of input parameters were performed before any simulations, and potential reasons for the possible deviations in results were discussed. Comparisons of numerical simulations and experimental test results reveal that, in most instances, numerically-calculated and experimentally obtained results are in good agreement. However, some of the obtained results deviate from the experimental ones. Poor calibration of the dynamic characteristics of the sand was primarily cited as the source of these differences. Nevertheless, these calibrations could accurately predict the laboratory's static results. Modifying the soil model's stiffness parameters brings the predicted results much closer to the experimental ones, but some unidentified deviations remain.

The Putaendo watershed (Central Andes, Chile), notable for its pre-colonial history and as the first independent Chilean town (1817), also exhibits special hydrological features. It is one of the few areas in the Andes Cordillera where the inhabitants rely almost entirely on periglacial water sources. Since 2010, the region has also experienced a severe megadrought, drastically altering the water supply and straining the livelihoods of pastoralists and peasants to the limit. However, despite the significant decrease in precipitation recorded during the megadrought, water continued to flow from the headwaters to the Putaendo River. To elucidate the mechanisms behind this water persistence, we quantified the individual contributions of different water sources (snow, rock glaciers, and groundwater) within this basin through the analysis of stable water isotopes and major ions. The region’s simple winter precipitation regime, another crucial hydrological characteristic, further facilitates the clear discrimination and quantification of meltwater inputs distinct from precipitation using physicochemical tracers. Additionally, to comprehensively understand public knowledge regarding water origin, the impact of the megadrought and climate change, and the potential development of mega-mining projects (as this is the last basin without this activity in the Chilean Central Andes), we conducted a social perception analysis using a cross-sectional descriptive survey with non-probabilistic causal sampling. Upstream of the Chacrillas dam’s, where there is minimal human intervention, the river in this arid water cycle exhibited a marked predominance of water contributions from rock glaciers (56.1%), followed by groundwater (32.7%) and snow (11.2%). The inhabitants of the territory domonstrates a remarkable awareness and prior knowledge, with 45.5% of respondents identifying rock glaciers as the main source of water during dry years. There was also a clear negative public opinion regarding the developing of mega-mining projects in the valley (84.1%). Integrating these perceptions of water scarcity’s social complexities with an advanced understanding of water source contribution provides crucial information for regional water security management.

BSTRACT, Th ere is a n as ymm etri c pa ttern res ponse o f g lac iers in Darwin C ordill e ra (54-55° S, 69-71 ° \ \') to th e clim a te o f th e 20 th ce n t ur)" Thi s asy mm e try is suggested he re as a ca use of a n in c reased wind ac ti\'ity II'hi c h has a pro no unced OJ'ogra phi c effec t. Altho ug h clim a ti c reco rd s for th e las t 50 yea rs show a warming trend , as we ll as no trend in prec ipitation in th e a rea, so me glac ie rs a re ad\'a ncing , Th e a rea is cha rac te ri zed by stro ng clim a ti c g radi e nts, with hi gh ra tes o f prec ipita tion on th e so uthwes te rn sid e of th e ra nge a nd dry co nditi o ns on th e no rth e rn sid e, Glaciers on th e north ern a nd eas tern sid es shO\\' a ge nera l tre nd of recedin g fro nts, " 'ith a fe w exce pti ons, th ese g lac iers ha \'e g ra duall y a nd uninterruptedl y bee n shrinking sin ce th e turn of th e ce ntury, On th e so uth ern rim, th e prese nt extents o f som e glaciers are simil a r to th eir 20th ce ntury m ax imum extents, Th ese a re, in turn , simil a r or close to th e H oloce ne maximum, Th e m os t extrem e sites a re th e g lac ie rs o n eith er sid e of :do unt D a r\\'in , II'hich is 2469 m hi g h, Th e no rth -fac ing glacie r V e nti squ ero :'1a rinelli has retrea ted se\'e ra l hundred m e tres per yea r o \, er th e las t twO d ecades, \\'hile th e so uth-fac ing g lac iers in th e Pa hi a Pi a bas in ha \'e ach'a nced durin g th e sa me peri od , In thi s stud y, th e fro nta l c h a nges o\'e r th e las t 50 years of 20 g laciers ha \'e b ee n a na lysed , A e ri a l ph o togra ph s (\'e rti ca ls) fr om 194 3 a nd 1984 ha ve bee n used , as w ell as obliqu e a e ri a l ph otog ra ph s fr o m ]993 , Th e ge neral res ult is th a t glac iers with acc umula ti o n a reas fac ing so uth a ndll'es t sho \\' so m e\\'ha t sta bl e fr o nts, \\'hil e g lacie rs fac ing eas t a nd no rth sho\\' receding front,

During the Japanese-Swedish Antarctic traverse expedition of 2007/08, we measured the surface snow density at 46 locations along the 2800 km long route from Syowa station to Wasa station in East Antarctica. The mean snow density for the upper 1 (or 0.5) m layer varied from 333 to 439 kg m -3 over a region spanning an elevation range of 365-3800 m a.s.l. The density variations were associated with the elevation of the sampling sites; the density decreased as the elevation increased, moving from the coastal region inland. However, the density was relatively insensitive to the change in elevation along the ridge on the Antarctic plateau between Dome F and Kohnen stations. Because surface wind is weak in this region, irrespective of elevation, the wind speed was suggested to play a key role in the near-surface densification. The results of multiple regression performed on the density using meteorological variables were significantly improved by the inclusion of wind speed as a predictor. The regression analysis yielded a linear dependence between the density and the wind speed, with a coefficient of 13.5 kg m -3 (m s -1 ) -1 . This relationship is nearly three times stronger than a value previously computed from a dataset available in Antarctica. Our data indicate that the wind speed is more important to estimates of the surface snow density in Antarctica than has been previously assumed.

A strong basis of observational data is crucial for improving the understanding of the physical processes driving these changes, and for improving models used to predict the state of the cryosphere in the future. mm /yr rise in sea level (unpublished data from IES and IMO; Björnsson et al., submitted). The DEMs are being used in several glaciological and geomorphological research projects of subglacial eruptions, jökulhlaups and hazard assessments for settlements near the glaciers and they will be useful in research of glacier dynamics such as studies of surges, calving, subglacial water flow and ice flow over bedrock topography. The very high resolution and good relative accuracy also make LiDAR maps useful for mapping crevasses and the creation of various special purpose maps of the glaciers, including maps to improve the safety of travel and search and rescue operations on the glaciers.

Glacier-surface displacements produced by geothermal and volcanic activity beneath Vatnajökull ice cap in Iceland are described by field surveys of the surface topography combined with interferograms acquired from repeat-pass synthetic aperture radar images. A simple ice-flow model serves well to confirm the basic interpretation of the observations. The observations cover the period October 1996–January 1999 and comprise: (a) the ice-flow field during the infilling of the depressions created by the subglacial Gjálp eruption of October 1996, (b) the extent and displacement of the floating ice cover of the subglacier lakes of Grímsvötn and the Skaftá cauldrons, (c) surface displacements above the subglacier pathways of the jökulhlaups from the Gjálp eruption site and the Grímsvötn lake, (d) detection of areas of increased basal sliding due to lubrication by water, and (e) detection of spots of temporal displacement that may be related to altering subglacial volcanic activity. At the d...

About 60% of glaciers in Iceland are underlain by an active volcanic zone (Fig. 1). Ice is continuously melted at a few subglacial geothermal areas (Fig. 2) and occasionally during short-lived eruptions. In about 4% of the area of Vatnajökull ice cap (8100 km2) geothermal activity eternally affects the ice flow and basal drainage of meltwater. During the period 1992 to 2005, more than 90% of the ablation within these areas was basal melting while less than 10% of the melting took place during two volcanic eruptions (1996 and 1998). Volcanic ...

We evaluate volume changes and mass balance of ice caps in Iceland by comparing digital elevation maps (DEMs), airborne altimetry and GPS field measurements. DEMs of the ice caps Langjökull and Mýrdalsjökull (in late August 2004 and 2006) were constructed from high resolution SPOT5 stereo pairs obtained by the across-track high-resolution-geometry (HRG) sensors. Spatial resolution up to 20x20 m and accuracy better than 2 m in elevation is achieved by using accurate ground control points on and around the ice caps. The ...

50 CLIMATE CHANGE RESPONSE OF THREE ICE CAPS IN ICELAND SVERRIR GUÐMUNDSSON 1, HELGI BJÖRNSSON 1, GUÐFINNA AÐALGEIRSDÓTTIR3, TÓMAS JÓHANNESSON 2, FINNUR PÁLSSON 1 AND ODDUR SIGURÐSSON 4 1 Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland 2 Icelandic Meteorological Office, Reykjavík, Iceland 3 Department of Geography, University of Wales Swansea, Swansea, UK 4 Hydrological Service, National Energy Authority, Reykjavík, Iceland Introduction The surface and bed topography of ...

Brúarjökull outlet glacier of Vatnajökull ice cap (red and magenta outlines), the river Jökla (blue), the glaciated area of the water drainage basin of Jökla (red outline), sites of the mass balance observations (black dots), meteorological stations,(red triangles, elevation in m asl) and discharge gauge for Jökla (magenta triangle).

Calving from tidewater glaciers and ice shelves accounts for around half the mass loss from both polar ice sheets, yet the process is not well represented in prognostic models of ice dynamics. Benn and others proposed a calving criterion appropriate for both grounded and floating glacier tongues or ice shelves, based on the penetration depth of transverse crevasses near the calving front, computed using Nye’s formula. The criterion is readily incorporated into glacier and ice-sheet models, but has not been fully validated with observations. We apply a three-dimensional extension of Benn and others’ criterion, incorporated into a full-Stokes model of glacier dynamics, to estimate the current position of the calving front of Johnsons Glacier, Antarctica. We find that two improvements to the original model are necessary to accurately reproduce the observed calving front: (1) computation of the tensile deviatoric stress opening the crevasse using the full-stress solution and (2) conside...

This paper presents the results of the glacier Inventory of James Ross and Vega islands based on topographic map sheets at 1:250 000 scale, Landsat multi-spectral scanner imagery in bands 4 and 7 at the same scale, and oblique air photographs obtained in 1979–80. Work was completed following the methodology proposed by the Temporary Technical Secretariat of the World Glacier Inventory. This is the first such inventory carried out in Antarctica.

The validity of any glaciological paleo proxy used to interpret climate records is based on the level of understanding of their transfer from the atmosphere into the ice sheet and their recording in the snowpack. Large spatial noise in snow properties is observed, as the wind constantly redistributes the deposited snow at the surface routed by the local topography. To increase the signal-tonoise ratio and getting a representative estimate of snow properties with respect to the high spatial variability, a large number of snow profiles is needed. However, the classical way of obtaining profiles via snow-pits is time and energy-consuming, and thus unfavourable for large surface sampling programs. In response, we present a dual-tube technique to sample the upper metre of the snowpack at a variable depth resolution with high efficiency. The developed device is robust and avoids contact with the samples by exhibiting two tubes attached alongside each other in order to (1) contain the snow core sample and (2) to access the bottom of the sample, respectively. We demonstrate the performance of the technique through two case studies in East Antarctica where we analysed the variability of water isotopes at a 100 m and 5 km spatial scales.

During the past three winters over 4000 km 2 of avalanche terrain in five mountain ranges in western Canada was zoned with the Avalanche Terrain Exposure Scale at the basin-scale (100 m to 1 km). Because the current ATES system isn't intended for this more deterministic application there are shortfalls with respect to subjectivity of terrain parameters and the lack of a nonavalanche terrain class. Although some digital terrain analysis was used to draw the initial ATES polygons, the methods relied primarily on the judgment of qualified field workers. This paper describes an approach and methodology for ATES zoning, and explores ideas for a more deterministic model including classification for non-avalanche terrain.

Dissertation:  Biological communities on Pacific Northwest temperate freshwater glaciers are unique and irreplaceable, but are highly threatened by glacial retreat.  53 glaciers in Montana, Alberta, British Columbia, Washington, Oregon, and California were surveyed as part of this study.
At least seven microbial morphotypes and 87 macroinvertebrate taxa were identified, including new species of Collembola and mesenchytraeid ice worms.  Habitat and geographic location were the most important factors in determining microbial and macroinvertebrate abundance, biomass and diversity.  Glacial snowpack held highest densities, followed by pools, with lowest densities in ice and supra-glacial streams.  Time of day and elevation had minor effect.  Macroinvertebrate density varied inversely with microbial densities.  They may be an important food source for some alpine birds, particularly the gray crowned rosy finch.
Relationships between ice worm populations were explored using nuclear 28S and mitochondrial CO1 DNA.  Temporal and geographic distance, and interposing low elevation land, determine inter-population distance.  Dispersal between glaciers is an extremely rare event, although perhaps the original source of Oregon populations.  This molecular evidence supports their usefulness as a model organism in ecological and evolutionary studies, particularly fragmentation of species with poor dispersal ability.
If retreat returns to pre-warming (1880-1979) rates, 21% of today's glaciers will be gone by 2050, and 34% by 2100.  If 1990-2004 rates continue, we will lose 34% of PNW glaciers within 50 years, and 100% loss within 100 years.  Larger glaciers will make up an increasing proportion of the remaining glaciers.  These changes will result in the permanent loss of many glacial species, and reduce the probability of long-term survival for others.  Glacier microbial contribution downstream may drop to between 18 and 46% current values over the next century.
Research efforts in California to southern British Columbia, and perhaps the Kenai, should place a high priority on recording biological diversity before its loss.  Central British Columbia through the St. Elias region in Alaska, as storehouses of glacial biodiversity, should focus on long-term monitoring and conservation of glacier biota.  Stream researchers and managers must consider the changing contributions of glaciers to streams in this region.

Seu conteúdo foi revisado pela Comissão Tecno-científica do I SR-SBGf mas não necessariamente representa a opinião da SBGf ou de seus associados. E proibida a reprodução total ou parcial deste material para propósitos comerciais sem prévia autorização da SBGf. ____________________________________________________________________ We present a historical overview of Euler deconvolution method which is the simplest and the most widely used method in aeromagnetic interpretation. We describe the state-of-the-art of Euler deconvolution: where we have been, where we are, and where we will be headed in the future. Inasmuch as it is review discussion about Euler deconvolution, we provide comprehensive view of the past, present, and future trends of this method.

Glacial retreat in recent decades has exposed unstable slopes and allowed deep water to extend beneath some of those slopes. Slope failure at the terminus of Tyndall Glacier on 17 October 2015 sent 180 million tons of rock into Taan Fiord, Alaska. The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups ever documented worldwide. Precursory deformation began decades before failure, and the event left a distinct sedimentary record, showing that geologic evidence can help understand past occurrences of similar events, and might provide forewarning. The event was detected within hours through automated seismological techniques, which also estimated the mass and direction of the slide -all of which were later confirmed by remote sensing. Our field observations provide a benchmark for modeling landslide and tsunami hazards. Inverse and forward modeling can provide the framework of a detailed understanding of the geologic and hazards implications of similar events. Our results call attention to an indirect effect of climate change that is increasing the frequency and magnitude of natural hazards near glaciated mountains. Climate change is driving worldwide glacial retreat and thinning 1 that can expose unstable hillslopes. The removal of glacial ice supporting steep slopes combined with the thawing of permafrost in alpine regions 2 increases the likelihood of landslides . Glaciers undercut slopes, priming them for failure by deepening and widening valley bottoms, and by producing steeper valley walls 7 . Additionally, ice loading produces stress fractures in the underlying bedrock, further preparing slopes for failure 8 . As climate warms and glaciers shrink and retreat, they can no longer support rock slopes, and fractures expand as stresses are released. This slope conditioning leads to rock falls, deep-seated gravitational slope deformation, and occasionally catastrophic rock avalanches . A further effect of glacial retreat is the creation or extension of bodies of deep water, fresh or marine , where tsunamis can be generated efficiently (Table ). Along the glacially sculpted coastlines of Alaska, Patagonia, Norway, and Greenland, communities, tourism, and infrastructure are becoming increasingly exposed to such

By comparing modelled and averaged satellite altimeter return, it is demonstrated that time profiles of altimeter return can be used to provide important information on the surface properties of the ice sheets. Altimeter ice-sheet radar echoes from low altitudes and/or relatively low latitudes are, in general, dominated by surface scattering and, in Greenland, the area of surface-dominated return broadly coincides with the zone of summer melting. Seasonal variations in the echo wave-form shapes are negligible in all regions studied, with the possible exception of an area near the margin of the Greenland dry-snow zone. In general, the model explains well the observed variations in mean wave-form shape, but small discrepances between the model wave forms and the recorded wave forms indicate that sub-surface layers may be influencing the shape of the return. The possibility of deriving quantitative estimates of surface properties is explored by fitting model returns to averaged altimet...

A comprehensive survey of the Larsen Ice Shelf has been conducted using precise orbit and retracked Seasat radar-altimeter data with editing of erroneous values resulting from intrumental artefacts. Contour maps of elevation and radar back-scatter (with absolute accuracies of 1 m and 2 dB, respectively) have been produced and it has also been possible to map rifts, grounding points, rough terrain, and about 30% of the ice shelf’s seaward margin. Ice thicknesses derived from these elevation data show broad agreement with those derived from previous airborne radio-echo surveys. The maps of parameters measured by Seasat represent a very substantial improvement over those previously available. They thus provide a reference against which comparison may be made with a view to detecting substantial climatic changes. This is of particular interest since, as the most northerly major ice shelf in Antarctica, the Larsen Ice Shelf may be more sensitive than others to global climatic trends.

Semi-permanent snow is part of the continuum between seasonal snow and glacier ice. Although ubiquitous in the High Arctic, most late-lying snow banks and snow beds have lost their perennial status over the past decade as the summers have become progressively warmer. The loss over the past decade is the most unprecedented since aerial photography of the Canadian Arctic islands was first undertaken over half a century ago, and it has produced observable thermal, hydrological and ecological impacts. Where the ground has become exposed beneath the perennial snow cover, seasonal ground thaw has deepened. Tundra ponds and patchy wetlands fed principally by meltwater in the summer have suffered water-level decline or desiccation. The water balance of headwater basins is also affected, losing a buffering vehicle that accumulates storage surplus from the wet cool years to support streamflow and evaporation in the dry warm years. The tundra vegetation, already sparse, undergoes changes in the long term. As an essential source of water in the polar desert environment, the widespread distribution of semi-permanent snow magnifies its Arctic-wide importance.

We observed several swarms of repeating low-frequency (1–5 Hz) seismic events during a 3 week period in May–June 2010, near the summit of Mount Rainier, Washington, USA, that likely were a result of stick–slip motion at the base of alpine glaciers. The dominant set of repeating events (‘multiplets’) featured >4000 individual events and did not exhibit daytime variations in recurrence interval or amplitude. Volcanoes and glaciers around the world are known to produce seismic signals with great variability in both frequency content and size. The low-frequency character and periodic recurrence of the Mount Rainier multiplets mimic long-period seismicity often seen at volcanoes, particularly during periods of unrest. However, their near-surface location, lack of common spectral peaks across the recording network, rapid attenuation of amplitudes with distance, and temporal correlation with weather systems all indicate that ice-related source mechanisms are the most likely explanation....

The Koshi River Basin, a transboundary river system with monsoon-driven hydrology, supports more than 15 million people by providing irrigation and potable water resources in Nepal and India. This study aims to evaluate the trace elements (TEs) spatiotemporal variation, identify their natural and anthropogenic sources, assess hydrological controls, and estimate human health risks. A total of 44 surface water samples were collected during dry and rainy seasons, and 17 dissolved TEs were measured in the laboratory. The Spatial Processes in Hydrology (SPHY) model was used to quantify contributions of glacier melt, snowmelt, base flow, and rainfall to the total runoff at each sampling site. The study revealed elevated concentrations of Sr, Fe, Li, Cs, Pb, U, As, Cr, and Ni in upstream regions, with most TEs declining during the rainy season. Geogenic weathering was the dominant TEs source in the KRB; however, the downstream enrichment was also linked to anthropogenic activities. Hydrological regimes played a key role: base flow dominated the dry season, enhanced TEs mobilization through rock-water interactions, whereas rainfall runoff dominated the rainy Guanxing Wang is Co-first author.

The development of land-fast sea ice and overlying snow was monitored during a 4 week period, until the snow cover had completely disappeared, at a site in the Gulf of Bothnia, Baltic Sea (63.578 N, 19.858 E). The meteorological and radiative boundary conditions were continuously recorded. During the observation period, a 15 cm thick snow layer on the ice was transformed into a 7 cm thick granular ice layer (superimposed ice) on the ice surface, contributing significantly (about 11%) to the total ice thickness. Approximately 1 cm w.e. of the snow was sublimated. Neither snow-ice formation nor basal ice growth was significant during the same period. The salinity and isotopic (d 18 O) composition of the ice indicated that prior to the experiment a 7 cm layer of superimposed ice had already formed. Hence, superimposed ice layers contributed 22% of the total ice thickness by the time all snow had disappeared. The advancing spring, decrease in surface albedo, diurnal cycle in the incoming solar radiation, and synoptic-scale changes in the cloud cover and the air-ice turbulent heat fluxes caused variations in the heat budget of the snowpack. Superimposed ice formation due to refreezing of meltwater occurred during most nights of the study period, and the most important refreezing periods were under such synoptic conditions that the air and snow surface temperatures also remained below zero during daytime. In contrast to typical summer conditions in polar oceans, low snow surface temperatures acted as the primary heat sink for the refreezing of meltwater.

The behavior of majorions, δ18O, dissolved organic carbon (DOC) and trace elements was studied during the initial freezing of low-saline water (3 practical salinity units) in a freezing experiment. Samples were also collected from first-year sea ice from pack ice in the Bothnian Bay, northern Baltic Sea. During initial ice formation, the major-ion ratios in sea ice indicated variable behavior, with some ions showing relative enrichment (sulfate, calcium and magnesium), conservative behavior (sodium) or relative depletion (potassium) compared to sea water at the same salinity. DOC, iron and aluminum showed enrichment in the ice, while zinc was depleted to salinity. Lead was detected in surface snow-ice layers only, implying atmospheric accumulation. First-year sea ice, with a variable growth and thermal history, showed behavior for major ions similar to that observed in new ice. However, for trace elements the picture was much more complicated, most likely due to active secondary pro...

Protection of groundwater against nitrate has a high priority in a country like Denmark with intensive agricultural production and with drinking water production based on groundwater. This paper presents a Site-specific Concept for Aquifer Nitrate Vulnerability Assessment (SCANVA) aimed at protecting groundwater resources. SCANVA is a qualitative dynamic concept adjusted to the specific study area depending on the hydrogeological and geochemical conditions. It comprises a synthesis of very detailed site-specific geological, geophysical, hydrogeological and chemical data, and a definition of nitrate vulnerability founded on redox conditions in the ground. Data are used to interpret the geological architecture of the subsurface, the groundwater flow and the geochemical groundwater conditions. These interpretations are integrated to assess nitrate vulnerability of the aquifers in three dimensions and identifying nitrate-vulnerable zones. The paper demonstrates the practical use of the concept in a Danish intensive agricultural area with a glacially formed landscape. Glaciotectonic has led to a high geological heterogeneity and very complex composition of thrusted and folded layers, which to a large extent affect the nitrate vulnerability of the aquifers. SCANVA can be directly applied to specific hydrogeological conditions anywhere with intensive N loss from agriculture, a groundwaterbased drinking water supply, nitrate reduction in the ground and glacially dominated landscapes and deposits. Potentially, the concept might also be adapted to other specific substances, dominating geochemical processes, and geological settings.

The glacial lake outburst due to moraine dam failure has been investigated through numerical model and flume experiments. A numerical model has been developed to compute the characteristics of the glacial lake outburst due to moraine dam failure by seepage flow and overtopping. Numerical analyses of seepage and moraine dam failure have been also performed. To compute the pore water pressure in the dam and slope stability of the dam, a seepage flow model and a slope stability model are incorporated into a numerical model of flow and dam surface erosion. The simulated results of the outburst discharge, seepage profile, failure surface and dam surface erosion are compared with the experimental results.

Moraine dam failure and Glacial Lake Outburst Flood (GLOF) are phenomena closely related to climate change. These events may cause floods of great magnitudes in the downstream river reaches. More than 61% of GLOFs were initiated by displacement waves from ice avalanches that collapsed into the lakes from hanging or calving glaciers and rock avalanches. However, in-depth knowledge of the mechanism of the dam failures by waves overtopping and measured data are still lacking. Extensive laboratory experiments are carried out to study such type of failure mechanism by varying size of ice/rock avalanche, shape of the dam, dam material and lake water level. The outflow hydrographs produced by waves overtopping and erosion consist multiple peaks. For the same falling block and lake water level, the initial peaks are similar for both triangular and trapezoidal dams. However, magnitude and timing of subsequent peaks are different according to dam shapes and dam materials.

This report summarizes an updated inventory of glaciers and perennial snowfields of the contiguous United States. The inventory is based on interpretation of mostly aerial imagery provided by the National Agricultural Imagery Program, U.S. Department of Agriculture with some satellite imagery in places where aerial imagery was not suitable. The inventory includes all perennial snow and ice features greater than 0.01 km 2 . Due to aerial survey schedules and seasonal snow cover, imagery acquired over a number of years were required. The earliest date is 2013 and the latest is 2020, but more than 73% of the outlines were acquired from 2015 imagery. The inventory is compiled as shapefiles within a geographic information system that includes feature classification, area, and location. The inventory identified 1331 (366.52 km 2 ) glaciers, 1776 (31.00 km 2 ) perennial snowfields, and 35 (3.57 km 2 ) buried-ice features. The data including both the shapefiles and tabulated results are publicly available at