the climate memory of an arctic polythermal glacier knowledge of glacier equilibrium line altitude ela changes and trends in time is essentialfor future predictions of glacier volumes we present a novel method for determining trends in elachange at mccall glacier alaska usa over the last 50 years based on mapping of the cold temperatetransition surface cts marking the limit between cold and temperate ice of a polythermal glacier latent heat release from percolating meltwater and precipitation keeps the ice column temperate in theaccumulation area a change from accumulation to ablation zone reduces this heat release leadinglocally to glacier ice cooling by mapping the cts along the whole glacier length using radio echosounding and employing a thermodynamic model the timing of the cooling was determined fromwhich past elas were constructed these are in accord with mass balance measurements carried out onmccall glacier since the 1950s we show that with a warming climate mccall glacier tends to cool ina counter intuitive way

mass balance of white glacier axel heiberg island n w t canada 1960 91 white glacier is a valley glacier at 79 5 n with an area of 38 7 km 2 its mass balance has been measured over 32 years with a 3 year gap by standard techniques using the stratigraphic system with a stake density of the order of one stake per km 2 errors in stake mass balance are about 200 250 mm due largely to the local unrepresentativeness of measurements errors in the whole glacier mass balance b are of the same order as single slake errors however the lag 1 autocorrelation in the time series of b is effectively zero so it consists of independent random samples and the error in the long term balance normal b is noticeably less b is 100 48 mm the equilibrium line altitude ela averages 970 m with a range of 470 1400 m mass balance is well correlated with ela but detailed modelling shows that the equilibrium line is undetectable on visible band satellite images a reduced network of a few stakes could give acceptable but less accurate estimates of the mass balance as could estimates based on data from a weather station 120 km away there is no evidence of a trend in the mass balance of white glacier to detect a climatologically plausible trend will require a ten fold reduction of measurement error a conclusion which may well apply to most estimates of mass balance based on similar stake densities

spatial and temporal variability in the snowpack of a high arctic ice cap implications for mass change measurements interpretation of ice mass elevation changes observed by satellite altimetry demands quantification of the proportion of elevation change which is attributable to variations in firn densification detailed stratigraphic logging of snowpack structure and density was carried out at 1k m intervals along a 47 km transect on devon ice cap canada in spring pre melt and autumn during after melt 2004 and 2006 to characterize seasonal snowpack variability across the full range of snow facies simultaneous meteorological measurements were gathered spring pre melt snowpacks show low variability over large spatial scales with low magnitude changes in density the end of summer autumn density profiles show high variability in both 2004 and 2006 with vastly different melt regimes generating dissimilar patterns of ice layer formation over the two melt seasons dye tracing experiments from spring to autumn 2006 reveal that vertical and horizontal distribution of meltwater flow within and below the annual snowpack is strongly affected by the pre existing often subtle stratigraphic interfaces in the snowpack rather than its bulk properties strong interannual variability suggests that using a simple relationship between air temperature elevation and snowpack densification to derive mass change from measurements of elevation change across high arctic ice caps may be misguided melt timing and duration are important extrinsic factors governing snowpack densification and ice layer formation in summer rather than averaged air temperatures

modelling the long term mass balance and firn evolution of glaciers around kongsfjorden svalbard we analyse the long term 1961 2012 distributed surface mass balance and firn evolution of the kongsvegen and holtedahlfonna glacier systems in northwestern svalbard we couple a surface energy balance model to a firn model with forcing provided from regional climate model output in situ observational data are used to calibrate model parameters and validate the output the simulated area averaged surface mass balance for 1961 2012 is slightly positive 0 08 m w e a 1 which only fractionally compensates for mass loss by calving refreezing of percolating water in spring summer 0 13 m w e a 1 and stored water in fall winter 0 18 m w e a 1 provides a buffer for runoff internal accumulation i e refreezing below the previous year s summer surface in the accumulation zone peaks up to 0 22 m w e a 1 and is unaccounted for by stake observations superimposed ice formation in the lower accumulation zone ranges as high as 0 25 m w e a 1 a comparison of the periods 1961 99 and 2000 12 reveals 21 higher annual melt rates since 2000 and a 31 increase in runoff which can only in part be ascribed to recent warmer and drier conditions in response to firn line retreat both albedo lowering snow ice albedo feedback and lower refreezing rates refreezing feedback further amplified runoff

mass balance flow and subglacial processes of a modelled younger dryas ice cap in scotland we use an empirically validated high resolution three dimensional ice sheet model to investigate the mass balance regime flow mechanisms and subglacial characteristics of a simulated younger dryas stadial ice cap in scotland and compare the resulting model forecasts with geological evidence input data for the model are basal topography a temperature forcing derived from grip 18 o fluctuations and a precipitation distribution interpolated from modern data the model employs a positive degree day scheme to calculate net mass balance within a domain of 112 500 km 2 which under the imposed climate gives rise to an elongate ice cap along the axis of the western scottish highlands at its maximum the ice cap is dynamically and thermally zoned reflecting topographic and climatic con trols respectively in order to link these palaeoglaciological conditions to geological interpretations we calculate the relative balance between sliding and creep within the simulated ice cap forecast areas of the ice cap with the greatest capacity for basal erosion and predict the likely pattern of subglacial drain age we conclude that ice flow in central areas of the ice cap is largely due to internal deformation and is associated with geological evidence of landscape preservation conversely the distribution of stream lined landforms is linked to faster flowing ice whose velocity is predominantly the result of basal sliding the geometry of the main ice mass focuses subglacial erosion in the mid sections of topographic troughs and produces glaciohydraulic gradients that favour subglacial drainage through low order arterial routes

observations of pronounced greenland ice sheet firn warming and implications for runoff production field measurements of shallow borehole temperatures in firn across the northern greenland ice sheet are collected during may 2013 sites first measured in 1952 1955 are revisited showing long term trends in firn temperature results indicate a pattern of substantial firn warming up to 5 7 c at midlevel elevations 1400 2500 m and little temperature change at high elevations 2500 m we find that latent heat transport into the firn due to meltwater percolation drives the observed warming modeling shows that heat is stored at depth for several years and energy delivered from consecutive melt events accumulates in the firn the observed warming is likely not yet in equilibrium with recent melt production rates but captures the progression of sites in the percolation facies toward net runoff production

permafrost active layer abstract this article discusses the properties and occurrence of an active layer al in the near surface of the lithosphere in glacial and periglacial environments this layer shows a seasonal variability in temperature as a result of the climate the al as classically understood seasonally thaws and freezes while in glacial environments it usually only reaches 0 c the definition of al is currently not consistent with the definition of permafrost even though both concepts usually appear linked for these terms to be comparable both should be defined based on temperature variability and not exclusively on phase change thus the al would be described not only as the upper section of perennially frozen ground presenting seasonal thaw freeze cycles 1 but as a layer presenting a seasonal variation in temperature 2 classical active layer can be thawed to a depth of approximately 2 8 cm the thickest al reaches over 20 m in the particularly favorable conditions al might be completely absent with the permafrost beginning at the ground surface in glacial and sub marine permafrost environments the al includes a layer of liquid water that seasonally accompanies the permafrost glaciers and ice sheets are usually devoid of the classical al in both cases the al is usually horizontal but in specific terrains such as sea shore cliffs or karst environments the al may have a vertical course and may even be reversed both al and permafrost are common in other frozen bodies in the solar system differing mainly in their thermal character

internal accumulation on storglaciaren sweden in a multi layer snow model coupled to a distributed energy and mass balance model to investigate the internal accumulation on storglaciaren sweden we couple a multilayer snow model to a distributed energy and mass balance model the snow model describes the temperature density and water content evolution of the snow ice pack and includes the processes of percolation and refreezing of water the model is run for the period 9 may 2 september 1999 and validated against weather station and mass balance observations on the glacier the model performs reasonably well with an average summer mass balance for the location of stake observations of 1 56 m w e compared to 1 59 m w e observed however the amount of melt is overestimated in the higher parts of the accumulation area and underestimated in the lower parts of the ablation area the modelled mass balance is most sensitive to the albedo parameterization the chosen momentum and scalar roughness lengths and all parameters related to snowfall the modelled internal accumulation is 0 25 m w e which amounts to about 20 of the winter accumulation and results in a positive net balance for 1999 of 0 23 m w e the modelled internal accumulation is most sensitive to the initial subsurface temperature profile and the irreducible water content

atmospheric warming threatens the untapped glacial archive of ortles mountain south tyrol ortles mountain 3905 m a s l south tyrol italy is the highest mountain of the eastern european alps and its upper glacier alto dell ortles presents a unique opportunity to obtain the first paleoenvironmental record from an ice core in this area to study the suitability of this glacier as a drilling site in 2009 we performed the first preliminary study of its glaciological characteristics at 3830 m a s l the maximum thickness is 75 m and lamination of the exposed ice layers is excellent down to bedrock firn and ice lenses were observed in a 10 m shallow core and the firn ice transition was below 24 m the seasonal chemical signal is clearly preserved only within the uppermost 2008 and 2009 snow firn a simple mass balance model the incipient smoothing of the chemical record and the observed ice lenses provide evidence that melting infiltration and refreezing cycles occurred within the firn layers formed before 2008 nevertheless the mass balance of the upper part of alto dell ortles was positive 800 mm a 1 during the last few years we suggest that an environmental history is likely to be well preserved only within the ice layers formed before 1980 when summer air temperature was 28c colder than today in this area clearly the continued warming trend predicted to occur over the next few decades and the consequent increase in frequency and or intensity of infiltration processes will endanger the preservation of the glacial archive conserved in the deep ice layers of ortles mountain

superimposed ice regime of a high arctic glacier inferred using ground penetrating radar flow modeling and ice cores 1 a 900 mhz ground penetrating radar gpr profile collected along 1 7 km of the centerline of a high arctic glacier in svalbard is interpreted using shallow ice core data and thermomechanical flow modeling four distinct zones are visible in the image and correspond to areas of firn recent and older superimposed ice and ablation zone glacier ice on the ground the areas of firn and superimposed ice are characterized by relatively steeply and gently dipping internal reflecting horizons irh respectively in the radar image the irhs arise from permittivity contrasts due to density variations produced in firn by alternating firn and ice layers and in superimposed ice by varying air bubble content recently formed and older superimposed ice can be distinguished in the gpr image a three dimensional flow model is used to indicate the long term mass balance and flow history responsible for the spatial distribution and orientation of superimposed ice irhs in the radar image results indicate that the irh distribution can only be explained by invoking a down glacier shift in mean 30 year equilibrium line altitude ela by 20 30 m compared with measured mean 30 year ela they also suggest that many of the superimposed irhs are relict features produced 100 years b p when the ela was 100 150 lower than at present this work advocates combined gpr and flow modeling as a unique tool for validating mass balance measurements and or inferring the mass balance dynamic history of a glacier beyond a recent measurement period

the mass balance of mccall glacier brooks range alaska u s a its regional relevance and implications for climate change in the arctic mccall glacier has the only long term mass balance record in arctic alaska average annual balances over the periods 1958 72 and 1972 93 were 15 and 33cm respectively recent annual balances 1993 96 are about 60 cm and the mass balance gradient has increased for an arctic glacier with its low mass exchange rate this marks a significant negative trend recently acquired elevation profiles of mccall glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973 most of these glaciers had average annual mass balances between 25 and 33 cm while mccall glacier averaged 28 cm for 1956 93 indicating that it is representative of the region in contrast changes in terminus position for the different glaciers vary markedly thus mass balance trends in this region cannot be estimated from fractional length changes at time scales of a few decades we developed a simple degree day accumulation mass balance model for mccall glacier the model was tested using precipitation and radiosonde temperatures from weather stations at inuvik canada and barrow kaktovik and fairbanks alaska and was calibrated with the measured balances the inuvik data reproduce all measured mass balances of mccall glacier well and also reproduce the long term trend towards more negative balances data from the other stations do not produce satisfactory model results we speculate that the arctic front oriented east west in this region causes the differences in model results

multiphase formation of superimposed ice during a mass balance year at a maritime high arctic glacier meteorological and snow temperature data from midtre lovenbreen spitsbergen svalbard indicate two distinct annual phases of rapid snowpack warming and superimposed ice formation in 1998 99 short periods of positive air temperatures in early winter lasting up to 36 hours and often coinciding with rainfall caused rapid glacier wide melting percolating water froze to form superimposed ice on the lower half of the glacier and wetted refrozen snow and ice lenses at higher altitudes the second period of superimposed ice formation commenced in may june 1999 and continued for 5 weeks at low altitudes and throughout the summer at high altitudes these observations at midtre lovenbreen are typical of spitsbergen glaciers and reflect the unique climatology of the region they contrast with those from glaciers in more continental climatic settings where superimposed ice formation is confined to a single period during summer there are significant implications for glacier mass balance with superimposed ice locally comprising up to 20 of winter balances and accounting for 16 25 of the annual accumulation since projected climatic warming is greatest during the winter months in arctic regions superimposed ice may become an increasingly important component of the winter and potentially the net balance of spitsbergen glaciers

superimposed ice in glacier mass balance on the tibetan plateau the relations betw een mass bal ance and meltwater refre ezing were examined on the basis of glac iolo gical obse rvations carried out in summer 1993 on xiao dongkemadi glacier tanggula mountai ns central tibetan plateau on this glacier a part of melt water refreezes at the snovv ice int erface as superimp osed ice the amount of supe rimp osed ice formation was determ ined by both meltw ater supply and temperat ure condit ion of the glaci er snow lay er thic kness on the glacier ice body is less than 2 m even in the higher accu mulat ion zone about 60 of meltw ater generate d in the accumula tion zone for the period v1ay september was trapped at the snow ice interface by refre ezing and was not dis charged out of the glacie r about 26 of accumulated snow to the glacier surface was repl aced on the snow ice interface by refreez ing in the accumulation zone these facts indicate that superim posed ice formation is quit e signifi cant for water retention in glaciers unde r low pre cipitation conditions

analysis of meteorological data and the surface energy balance of mccall glacier alaska usa we report on analysis of meteorological data for the period 27 may 20 august 2004 from two automatic weather stations on mccall glacier alaska usa aimed at studying the relationship between climate and ablation one station is located on a mountain ridge and the other in the ablation area where we also analyzed the energy balance the weather station on the glacier measured an average temperature of 5 38c at 2m height above surface and wind speed of 3 1ms 1 at 3m height a sonic height ranger and ablation stakes indicate a specific mass balance of 1 94 0 09mw e between 15 june and 20 august the specific mass balance calculated from the surface energy balance 2 06 0 18mw e is in close correspondence to this the latter is the sum of 0 12mw e of snowfall 0 003mw e of deposition and 2 18mw e of melt net radiation contributes 74 of the melt energy compared to ablation measurements in the early 1970s summer ablation was large this increase is explained by a combination of a relatively higher net radiation a lower albedo and larger turbulent heat fluxes that led to more energy being available for melting no single meteorological variable can be isolated as being the principal reason for the high ablation however the lower ice albedo 0 19 is possibly due to ash deposits from forest fires

chemistry isotope values δd δ18o δ34sso4 and temperatures of the water inflows in two gotthard tunnels swiss alps water inflows in the gotthard highway tunnel and in the gotthard exploration tunnel are meteoric waters infiltrating at different elevations on both sides of an important orographic divide limited interaction of meteoric waters with gneissic rocks produces ca hco3 and na ca hco3 waters whereas prolonged interaction of meteoric waters with the same rocks generates na hco3 to na so4 waters waters circulating in triassic carbonate evaporite rocks have a ca so4 composition calcium na so4 waters are also present they can be produced through interaction of either na hco3 waters with anhydrite or ca so4 waters with a local gneissic rock as suggested by reaction path modeling an analogous simulation indicates that na hco3 waters are generated through interaction of ca hco3 waters with a local gneissic rock the two main so4 sources present in the alps are leaching of upper triassic sulfate minerals and oxidative dissolution of sulfide minerals of crystalline rocks values of 34sso4 9 are controlled either by bacterial so4 reduction or leaching of upper triassic sulfate minerals most waters have temperatures similar to the expected values for a geothermal gradient of 22 c km and are close to thermal equilibrium with rocks however relatively large descending flows of cold waters and ascending flows of warm waters are present in both tunnels and determine substantial cooling and heating respectively of the interacting rocks the most import upflow zone of warm na rich waters is below guspisbach in the gotthard highway tunnel at 6 2 9 0 km from the southern portal these warm waters have equilibrium temperatures of 65 75 c and therefore constitute an important low enthalpy geothermal resource

the quaternary coral reef tracts of hateruma ryukyu islands japan the island of hateruma is located at the southwestern end of the ryukyu island chain and covers an area of about 15 km2 with its highest point at 59 5 m a s l the morphology of hateruma is characterized by an eight step staircase i to viii after ota et al 1982 most of which eroded into the previously formed coral reefs ii and iv to viii this study presents 100 age estimations on 43 coral samples using electron spin resonance esr alpha and mass spectrometric u series methods the dating results imply that the ryukyu limestone was predominantly formed during oxygen isotope stages 7 and 5e two age estimates of around 300 ka suggest an earlier reef building period the main problem for establishing the quaternary history of hateruma lies in the fact that the coral ages and the staircase morphology do not correlate additionally it is difficult to distinguish autochthonous from allochthonous samples the latter having possibly been relocated by tsunamis corals relating to substages 5a and 5c around 75 and 105 ka respectively are found in the immediate vicinity of much older samples the results of this study prove the disappointing fact that hateruma cannot yet be used as a tool for reconstructing palaeo sea levels

chemical evolution of waters during long term interaction with granitic rocks in northern switzerland abstract as part of an assessment of crystalline rock as a potential host for a nuclear waste repository water samples were collected from more than 50 locations from the crystalline basement where it is under sedimentary cover in northern switzerland and where it is at the surface in the black forest these samples describe the changing chemistry of water in an extended flow system from dilute recharge waters far from chemical equilibrium with its host rock to saline waters at temperatures of 50 to 100 c with residence times far in excess of 105 a that have reached chemical equilibrium with their host rock this unique set of samples allows an analysis of the chemical evolution of granitic waters from surficial waters far from equilibrium to almost equilibrated waters mobile ions rare gases and isotopic data are used to estimate the extent of reaction between waters and their host rock the evolution of controlled elements is interpreted as a function of this extent of reaction silica contents correspond to approximate equilibrium even in the recharge waters the relative concentrations of ca and especially mg are significantly lower in the borehole waters than in recharge waters indicating a trend towards equilibrium the na k ratios correspond to equilibrium only in the most evolved older waters which are shown to be at full equilibrium

integrated assessment of changes in freshwater inflow to the arctic ocean we present an integrated and updated quantitative estimation of the river discharge and the meltwater flux and mass contributions from glaciers to the arctic ocean and to sea level rise the averag

variations of near surface firn density in the lower accumulation area of the greenland ice sheet pâkitsoq west greenland firn density variations have been studied in the lower accumulation area of the greenland ice sheet 1440 1620 m a s l near p kitsoq west greenland the main control on density in the near surface firn layer of 5 10 m thickness is the formation of ice layers by the refreezing of meltwater that reaches depths of 2 4 m below the surface the density variations are described by the ratio of annual surface melt m to the annual accumulation c the ratio m c is about 0 6 at the run off limit at about 1400 m a s l in the study area where refreezing of meltwater transforms snow into impermeable ice the mean density of near surface firn decreases with elevation reflecting a decrease in melt with elevation there is a surprising decrease in firn density at depths of more than about 4 m below the 1991 summer surface which reflects lower melt rates and or higher accumulation in the early 1980s and late 1970s when this firn was passing through the surface layer the formation of such low density firn may have partially contributed to the 1978 85 thickening of the ice sheet observed by satellite radar altimetry near surface firn density is therefore very sensitive to climate change and might be an attractive target for climate monitoring

internal accumulation in firn and its significance for the mass balance of storglaciaren sweden the discussion on global change has led to increased interest in glacier mass balance since glaciers can be used as climatic indicators to meet the need for high quality mass balance data requires critical examination of traditional mass balance methods and their possible errors one issue regarding mass balance measurements that has received little attention is internal accumulation our study shows that internal accumulation in the firn layer of storglaciaren sweden significantly affects the mass balance of the glacier this occurs because the winter cold wave penetrates below the previous year s summer surface and into underlying firn we estimated internal accumulation from measurements of temperature and water content in firn the depth of the 0 c isotherm correlated with snow depth and air temperature so that low snow depth and low air temperature separately cause a deeper 0 c isotherm we determined irreducible gravimetric water content in firn to 2 3 which corresponds to an irreducible water saturation of 6 8 our value for firn is relatively high compared with that for snow probably due to trapped water in isolated firn pores refreezing of percolating meltwater in spring accounted for 30 of annual internal accumulation the remaining 70 was due to refreezing of retained capillary water in firn pores during winter disregarding internal accumulation would lead to underestimation of annual net mass balance by 0 04 0 06 m w e corresponding to 3 5 of annual accumulation of the entire glacier in an average year hence internal accumulation potentially becomes a source for systematic error if not accounted in mass balance measurements

cold temperate transition surface and permafrost base cts pb as an environmental axis in glacier permafrost relationship based on research carried out on the storglaciaren and its forefield northern sweden here we present empirical ground penetrating radar gpr and electroresistivity tomography data ert to verify the cold temperate transition surface permafrost base cts pb axis theoretical model the data were collected from storglaciaren in tarfala northern sweden and its forefield the gpr results show a material relation between the glacial ice and the sediments incorporated in the glacier and a geophysical relation between the cold ice and the temperate ice layers clearly identifying lateral glacier margins is difficult as periglacial and glacial environments frequently overlap in this case we identified areas showing permafrost aggradation already under the glacier particularly where the cts is replaced by the pb surface this structure appears as a result of the influence of a cold climate over both the glacial and periglacial environments the results show how these surfaces form a specific continuous environmental axis thus both glacial and periglacial areas can be treated uniformly as a specific continuum in the geophysical sense similarly other examples previously described also allow identifying a continuation of permafrost from the periglacial environment onto the glacial base in addition the ert results show the presence of double layered periglacial permafrost possibly suggesting a past climatic fluctuation in the study area