variations of the snow physical parameters and their effects on albedo in sapporo japan continuous measurements of the radiation budget and meteorological components along with frequent snow pit work were performed in sapporo hokkaido japan during two winters from 2003 to 2005 the measured relationships between broadband albedos and the mass concentration of snow impurities were compared with theoretically predicted relationships calculated using a radiative transfer model for the atmosphere snow system in which different types in light absorption of impurity models based on mineral dust and soot were assumed the result suggests that the snow in sapporo was contaminated not only with mineral dust but also with more absorptive soot a comparison of the measured relationships between broadband albedos and snow grain size for two different layers with the theoretically predicted relationships revealed that the visible albedo contains information about the snow grain size in deeper snow layers 10 cm and the near infrared albedo contains only surface information this is due to the difference in penetration depth of solar radiation into snow between the visible and the near infrared wavelengths

measurement and parameterization of albedo variations at haut glacier d arolla switzerland spatial and temporal variations of surface albedo on haut glacier d arolla switzerland during the 1993 and 1994 ablation seasons are described correlation and regression analyses are used to explain the albedo variations in terms of independent meteorological and surface property variables parameterizations are developed which allow estimation of albedo variation in surface energy balance models snow albedo is best estimated from accumulated daily maximum temperatures since snowfall on deep snow 0 5 cm w e depth a logarithmic function is used while on shallow snow 0 5 cm w e depth an exponential function is used to enable the albedo to decay to the underlying ice or debris albedo the transition from deep to shallow snow is calculated as a function of decreasing snow depth combined r 2 0 65 this new parameterization performs better than earlier schemes because accumulated daily maximum temperatures since snowfall correlate strongly with snow grain size and impurity concentration the main physical controls on snow albedo ice albedo may be parameterized by its relationship to elevation r 2 0 28 but this approach results in only a small improvement over the assumption of a constant mean ice albedo

a distributed temperature index ice and snowmelt model including potential direct solar radiation hourly melt and discharge of storglaciaren a small glacier in sweden were computed for two melt seasons applying temperature index methods to a 30 m resolution grid for the melt component the classical degree day method yielded a good simulation of the seasonal patient of discharge but the pronounced melt induced daily discharge cycles were not captured modelled degree day factors calculated for every hour and each gridcell from melt obtained from a distributed energy balance model varied substantially both diurnally and spatially a new distributed temperature index model is suggested attempting to capture both the pronounced diurnal melt cycles and the spatial variations in melt due to the effects of surrounding topography this is accomplished by including a radiation index in terms of potential clear sky direct solar radiation and thus without the need for other data besides air temperature this approach improved considerably the simulation of diurnal discharge fluctuations and yielded a more realistic spatial distribution of melt rates the incorporation of measured global radiation to account for the reduction in direct solar radiation due to cloudiness did not lead to additional improvement in model performance

instruments and methods glaciological and volumetric mass balance measurements error analysis over 51 years for glacier de sarennes french alps the mass balance of glacier de sarennes french alps has been measured since 1949 using the glaciological method based on core and ablation stake data and area extrapolations to find the overall glacier balance the cumulative balance obtained in this way is very dependent on systematic errors that can increase linearly with the number n of measurement years whereas random errors rise with the volumetric balance method based on aerial photogrammetry provides results whose errors do not depend on the number of years this method was used to test field measurements for the period 1952 2003 and gives a mass balance of 32 30 1 04 m w e compared to 34 89 1 15 m w e based on field data the discrepancy between the two methods is discussed on the basis of a careful error analysis moreover the possibility of using the volumetric method to detect biases in field measurements is evaluated in terms of two types of errors the number and locations of measurement sites required to account for all the spatial and temporal variabilities of the mass balance is discussed by variance analysis methodological implications and recommendations are presented to provide mass balance measurements of the best possible accuracy

positive degree day factors for ablation on the greenland ice sheet studied by energy balance modelling ice ablation is related to air temperature by the positive degree day factor variations of the positive degree day factor in west greenland are studied using an energy balance model to simulate ablation under different conditions degree day factors for simulated and measured ice ablation at nordbogletscher and qaman rssup sermia agree well with values around 8 mm d 1 c 1 degree day factors for snow are less than half those for ice energy balance modelling shows that degree day factors vary with summer mean temperature surface albedo and turbulence but there is only evidence of large positive degree day factors at lower temperatures and with low albedo 0 3 the greatest effect of albedo variations 0 3 0 7 is at lower temperatures while variations in turbulence have greater effect at higher temperatures current models may underestimate runoff from the greenland ice sheet by several tenths because they use a degree day factor for melting ice that is too small for the colder parts of the ice sheet i e the upper ablation area and the northerly margin

snow accumulation and ice flow at dome du gouter 4300 m mont blanc french alps glaciological experiments have been carried out at dome du gouter 4300 m a s l mont blanc in order to understand the flow of firn ice in this high altitude alpine glacierized area accumulation measurements from stakes show a very strong spatial variability and an unusual feature of mass balance fluctuations for the alps i e the snow accumulation does not show any seasonal patterns measured vertical velocities which should match with long term mean mass balance are consistent with observed accumulations therefore the measurement of vertical velocities seems a good way of quickly obtaining reliable mean accumulation values for several decades in such a region a simple flow model can be used to determine the main flowlines of the glacier and to propose snow ice age of core samples from the two boreholes drilled down t the bedrock in june 1994 these results coincide with radioactivity measurements made to identify the well known radioactive snow layers of 1963 and 1986 we can hope to obtain ice samples 55 60 years old about 20 or 30 m above the bedrock 110 m deep below the deformation of the ice layers is loo great to be dated accurately

climate warming revealed by englacial temperatures at col du dome 4250 m mont blanc area 1 temperatures were measured in two deep boreholes drilled at the same location in the ice at col du dome 4250 m in 1994 and 2005 providing clear evidence of atmospheric warming the 1994 temperature profile was already far from steady state conditions results from a heat transfer model reveal that the englacial temperature increase cannot be explained solely by atmospheric temperature rise the latent heat produced by the refreezing of surface meltwater below the surface also contributes to the englacial temperature increase although surface melting is normally very low at this altitude this contribution became significant after 1980 for temperatures at the top of the borehole simulations for different climatic scenarios show that glaciated areas located between 3500 and 4250 m could become temperate in the future this warming could have a major impact on the stability of hanging glaciers frozen to their beds if the melting point is reached

methodological approaches to infer end of winter snow distribution on alpine glaciers snow accumulation is an important component of the mass balance of alpine glaciers to improve our understanding of the processes related to accumulation and their representation in state of the art mass balance models extensive field measurements are required we present measurements of snow accumulation distribution on findelengletscher switzerland for april 2010 using 1 in situ snow probings 2 airborne ground penetrating radar gpr and 3 differencing of two airborne light detection and ranging lidar digital elevation models dems calculating high resolution snow depth from dem differencing requires careful correction for vertical ice flow velocity and densification in the accumulation area all three methods reveal a general increase in snow depth with elevation but also a significant small scale spatial variability lidar differencing and in situ snow probings show good agreement for the mean specific winter balance 0 72 and 0 78 m w e respectively the lidar derived distributed snow depth reveals significant zonal correlations with elevation slope and curvature in a multiple linear regression model unlike lidar differencing gpr derived snow depth is not affected by glacier dynamics or firn compaction but to a smaller degree by snow density and liquid water content it is thus a valuable independent data source for validation the simultaneous availability of the three datasets facilitates the comparison of the methods and contributes to a better understanding of processes that govern winter accumulation distribution on alpine glaciers

25 years 1981 2005 of equilibrium line altitude and mass balance reconstruction on glacier blanc french alps using remote sensing methods and meteorological data annual equilibrium line altitude ela and surface mass balance of glacier blanc ecrins region french alps were reconstructed from a 25 year time series of satellite images 1981 2005 the remote sensing method used was based on identification of the snowline which is easy to discern on optical satellite images taken at the end of the ablation season in addition surface mass balances at the ela were reconstructed for the same period using meteorological data from three nearby weather stations a comparison of the two types of series reveals a correlation of r 0 67 at the 0 01 level of significance furthermore the surface mass balances obtained from remote sensing data are consistent with those obtained from field measurements on five other french glaciers r 0 76 p 0 01 also consistent for glacier blanc is the total mass loss 10 8mw e over the studied period however the surface mass balances obtained with the remote sensing method show lower interannual variability given that the remote sensing method is based on changes in the ela this difference probably results from the lower sensitivity of the surface mass balance to climate parameters at the ela

ice ablation as evidence of climate change in the alps over the 20th century 1 over fifty years of cumulative annual mass balance data for several glaciers in the alps shows similar fluctuations which seem to provide evidence of a common climatic signal separate winter and summer mass balance measurements from the claridenfirn glacier in switzerland since 1914 and the sarennes glacier france since 1949 show that 1 the annual mass balance is primarily driven by the summer mass balance term and 2 melting rate variations with time are very similar for these two glaciers located 290 km apart the increase in the ablation rate of 0 5 cm w e day 1 between the two periods 1954 1981 and 1982 2002 over these two glaciers corresponds to a 20 wm 2 rise in the energy flux at the glacier surface these results suggest that a common summer melting rate change may have affected the alps as a whole detailed observations on the sarennes glacier show that the origin of this strong increase in summer ablation since 1982 is not only a rise in the summer melting rate but also an increase in the ablation period during the months of september and october

which empirical model is best suited to simulate glacier mass balances based on an extensive dataset of surface mass balances smb from four glaciers in the french alps for the period 1995 2012 and in the framework of enhanced temperature index models we investigate the sensitivity of seasonal glacier smb to temperature solar radiation precipitation and topographical variables our results reveal strong correlations between winter smb and precipitation although the precipitation gradient cannot explain the high accumulation rates based on the available point measurements we found no relevant relationship between winter smb and topographical variables temperature was found to be the main driver of ice snow ablation while solar radiation was found to strongly influence the spatial distribution of summer smb we compared the ability of several enhanced temperature index models to accurately simulate point smb and glacier wide mb our analyses revealed that the uncertainties in the simulated annual smb due to winter smb uncertainties are larger than differences between models and prevented us from concluding which model is the most suitable in contrast with results of previous studies including solar radiation in melt models did not improve the performances when modelling glacier wide mb we conclude that a classical degree day model is sufficient to simulate the long term glacier wide mb if the underlying processes are not required to be resolved

l apatite de durango mexique analyse d un mineral standard pour la datation par traces de fission abstract durango apatite is analyzed by four analysts using three different dating techniques both the annealing technique and the external detector technique are applied to basal and prismatic sections cut from single crystals the population technique is applied to mounts of randomly oriented grains provided an individual determination of the geometry factor is performed all ages are indistinguishable from the reference age of 31 4 0 5 ma there is no noticeable influence of either the dating technique or the crystallographic orientation of the dated section on the ft age based on the projected lengths of surface tracks spontaneous track length reduction varies from 4 to 10 mean 6 depending on the analyst two simple corrections are applied to eliminate the net effect of the missing short tracks on the mean projected length after correction the amount of shortening of the spontaneous tracks is found to be slightly larger mean 8 but is still dependent on the analyst 4 to 12 the mean is in fairly good agreement with the value obtained from confined track length measurements 9 finally an isochronal 1 h plateau annealing procedure was applied to a separate set of basal and prismatic sections cut from the same single crystals annealing temperatures up to 300 c do not affect the ft age erratic ages at 350 c are ascribed to the occurrence of unetchable gaps it is argued that the absence of a distinct plateau up to temperatures where it could be expected from theoretical considerations indicates that the ft age of durango apatite needs no correction

application of the topographic position index to heterogeneous landscapes topographic position index tpi is an algorithm increasingly used to measure topographic slope positions and to automate landform classifications we applied tpi to a geoarchaeological research project in northwestern belgium but its use led to erroneous landform classifications in this heterogeneous landscape we asked whether deviation from mean elevation dev was a better method for landform classification than tpi we found that it enabled more accurate geomorphological assessment when using northwestern belgium as a case study

surface mass balance of glaciers in the french alps distributed modeling and sensitivity to climate change a new physically based distributed surface mass balance model is presented for alpine glaciers based on the crocus prognostic snow model it resolves both the temporal 1 hour time step and spatial 200 m grid step variability of the energy and mass balance of glaciers mass balance reconstructions for the period 1981 2004 are produced using meteorological reconstruction from the safran meteorological model for glacier de saint sorlin and glacier d argentiere french alps both glaciers lost mass at an accelerated rate in the last 23 years the spatial distribution of precipitation within the model grid is adjusted using field mass balance measurements this is the only correction made to the safran meteorological input to the glacier model which also includes surface atmospheric temperature moisture wind and all components of downward radiation independent data from satellite imagery and geodetic measurements are used for model validation with this model glacier sensitivity to climate change can be separately evaluated with respect to a full range of meteorological parameters whereas simpler models such as degree day models only account for temperature and precipitation we provide results for both mass balance and equilibrium line altitude ela using a generic alpine glacier the sensitivity of the ela to air temperature alone is found to be 125 m c 1 or 160 m c 1 if concurrent stefan boltzmann longwave radiation change is taken into account

3 d prestack depth migration in anisotropic media a case study at the lodgepole reef play in north dakota a key problem in interpreting depth migrated sections prestack or poststack is that seismic horizons almost never agree with well tops often seismic events are on the order of 1000 ft deeper seismic anisotropy is mostly blamed for the discrepancy in this paper we show a case study at the lodgepole reef play in north dakota where by incorporating strong seismic anisotropy in a 3 d velocity model we can achieve good depth migration results and excellent well ties within 50 ft our estimate of anisotropy parameters agrees with laboratory measurements on core samples in 1996 shell acquired 200 miles2 of 3 d seismic data in north dakota to explore for mississippian age lodgepole mounds structure in williston basin is relatively uncomplicated but prospecting for subtle structures and for stratigraphic traps which include the lodgepole is made more difficult by a number of geologic factors that affect both time and depth imaging exploration targets in the lodgepole play near dickinson north dakota lie at 9500 ft drill depths about 1 9 s two way time the geologic section is relatively flat lying and includes a broad range of lithologies and depositional environments the upper half section is dominated by shales and sandstones and the lower half by carbonates typical succession and alternation of lithologies at a closer scale shows great variation numerous formations consist of anhydrite and halite and in many areas salts have undergone partial or complete dissolution the dissolution shows both time and areal variation and the overlying formations carry this imprint into their original depositional and later diagenetic patterns other formations show significant lateral thickness variations due to sand dune distribution or to local patterns of thins and thicks which result from widespread and intermittently active vertical fault systems interacting with frequent episodes of uplift and subsidence success in the lodgepole exploration play has

mountain snow distribution governed by an altitudinal gradient and terrain roughness 1 the heterogeneous mountain snow cover is challenging the eye and the analytical mind of the observer the snow distribution affects water resources natural hazards such as avalanches and ecology while a lot of recent research has helped to better understand this snow distribution and the processes that cause the heterogeneity it has not yet been possible to predict snow distribution satisfactorily on the basis of terrain parameters alone we present a model of the mean snow depth in topographic control units as a function of two terrain parameters the conventional elevation plus a fractal roughness parameter for this we used a unique data set of high resolution measurements of snow depth from an airborne laser scanner the model captures the heterogeneous snow distribution by merely analysing the terrain and the mean precipitation this unusually simple relationship holds for clusters of the snow depths of small topographical units by applying fractal analysis we describe the roughness of the terrain and use this parameter for the prediction of snow deposition rougher terrain holds less snow than smoother terrain this finding is important not only for avalanche warning or eco hydrological applications but also for reliably predicting how snow water storage may change in the light of the pronounced climate change already ongoing in mountain regions

a new approach to resolving climate cryosphere relations downscaling climate dynamics to glacier scale mass and energy balance without statistical scale linking 1 we present a novel combination of methods to quantify the local mass response of mountain glaciers to large scale circulation previously such multiscale approaches bypassed the mesoscale processes of the mountain induced atmospheric flow by statistical transfer functions or subgrid parameterizations and included simplified glacier mass balance mb models here we show on the basis of kilimanjaro east africa as a test case that a limited area atmospheric model lam and a process resolving mb model can be linked without statistical corrections at their interface this is evident from robust energy and mb patterns at the glacier surface regardless of whether the mb model is forced by 1 in situ meteorological measurements or 2 uncorrected output from the high resolution lam grid over the glacier area the latter is achieved by multiple grid nesting in the land atmosphere ocean domain of the lam since this setup resolves the mesoscale process space we also show the potential to increase knowledge of how dynamical thermodynamic and microphysical phenomena of the mountain induced flow affect glacier mb all these results are encouraging for future research because they demonstrate that a dynamical system which operates on very different space time scales can be quantified in a fully physical way if dynamic meteorology and glaciology are exploited in a complementary sense this will enhance the process understanding of forward problems glacier response to climate forcing and backward problems climate signal extraction from past extents of mountain glaciers

an enhanced temperature index glacier melt model including the shortwave radiation balance development and testing for haut glacier d arolla switzerland an enhanced temperature index glacier melt model incorporating incoming shortwave radiation and albedo is presented the model is an attempt to combine the high temporal resolution and accuracy of physically based melt models with the lower data requirements and computational simplicity of empirical melt models represented by the degree day method and its variants the model is run with both measured and modelled radiation data to test its applicability to glaciers with differing data availability five automatic weather stations were established on haut glacier d arolla switzerland between may and september 2001 reference surface melt rates were calculated using a physically based energy balance melt model the performance of the enhanced temperature index model was tested at each of the four validation stations by comparing predicted hourly melt rates with reference melt rates predictions made with three other temperature index models were evaluated in the same way for comparison the enhanced temperature index model offers significant improvements over the other temperature index models and accounts for 90 95 of the variation in the reference melt rate the improvement is lower but still significant when the model is forced by modelled shortwave radiation data thus offering a better alternative to existing models that require only temperature data input

assessing the transferability and robustness of an enhanced temperature index glacier melt model we investigate the transferability of an enhanced temperature index melt model that was developed and tested on haut glacier d arolla switzerland in the 2001 season the model s empirical parameters temperature factor tf and shortwave radiation factor srf are recalibrated for 1 other locations on haut glacier d arolla 2 subperiods of distinct meteorological conditions 3 different years on haut glacier d arolla and 4 other glaciers in different years the model parameters are optimized against simulations of an energy balance model validated against ablation observations results are compared with those obtained with the original parameters the model works very well when applied to other sites seasons and glaciers with the exception of overcast conditions differences are due to underestimation of high melt rates the parameter values are associated with the prevailing energy balance conditions showing that high srf are obtained on clear sky days whereas higher tf are typical of locations where glacier winds prevail and turbulent fluxes are high we also provide a range of parameters clearly associated with the site s location and its meteorological characteristics that could help to assign parameter values to sites where few data are available

wind influence on snow depth distribution and accumulation over glaciers 1 in mountain regions wind is known to cause snow redistribution while physically based models of snow redistribution have been developed for flat to gently rolling terrain extension of these findings to steep terrain has been limited by the complexity of wind fields in such areas in this study we applied a nonhydrostatic and compressible atmospheric prediction model to steep alpine topography and compared the results to a fully distributed data set of snow depth estimations the results show reduced horizontal wind velocity as well as an increasing downward vertical wind velocity over areas with the largest winter accumulation which are mostly glacierized we show that the wind velocity normal to the local surface which should be zero in a nondivergent flow field and is a direct measure of increased or decreased local deposition is a function of small scale features of local topography the correlation between wind fields snow accumulation and glacierization suggests that accurate modeling of wind fields over glacierized areas in complex terrain is a key factor for understanding the mass balance distribution of glaciers

strong spatial variability of snow accumulation observed with helicopter borne gpr on two adjacent alpine glaciers the spatial distribution of snow accumulation plays an essential role for the mass balancedistribution on alpine glaciers traditional point measurements snow pits and probes are labour intensive and interpolation in between the points causes uncertainties airborne radar measurements have already been used for snow mapping innon glacierized terrain but not on alpine glaciers to enhance our understanding ofthe spatial distribution of accumulation and pin down reasons for observed variations we have conducted high resolution helicopter borne radar measurements on the temperatedglacier findel and neighbouring adler glacier in southwestern switzerland the radar sensor was mounted underneath a helicopter and operated at a centre frequencyof 500 mhz with a bandwidth of 400 mhz the results were validated withextensive ground based profiling of the snow cover the radar data allows a clearrecognition of the snow cover 6 of the total profile length of 10 km did not allowinterpretation due to missing or disturbed layering and agreed well with the groundbased measurements r2 0 85 reduced accumulation has been observed in allcrevassed zones statistical analysis of the correlation between observed accumulationand terrain characteristics have been performed in a gis environment revealing differingaccumulation patterns on the lower part of findel glacier accumulation showsa clear altitudinal trend while the upper part is dominated by strongly varying snowdepth without an altitudinal trend the accumulation characteristic on adler glacieris similar to the upper part of findel glacier but despite of their close vicinity accumulationis reduced by 40 compared to the same elevation on findel glacier thisstudy reveals a large potential of helicopter borne snow profiling for measurements ofaccumulation distribution on alpine glaciers