spatial and temporal variations of albedo on nine glaciers in western china from 2000 to 2011 this research demonstrates the spatiotemporal variations of albedo on nine glaciers in western china during 2000 2011 by the albedo derived from two types of datasets landsat tm etm images and mod10a1 product then the influence factors of glacier albedo and its relationship with glacier mass balance are also analyzed by the correlation approach which is frequently used in geostatistics the paper finds that there are different spatiotemporal variations over the glaciers in western china 1 for a single glacier the albedo varies gently with altitude on its tongue and increases fast in the middle part while in the accumulation zones the albedo value appears in the form of fluctuation this could provide a quantitative method to retrieve the snowline by determining the threshold albedo value of snowpack and bare ice 2 for the glaciers in western china the albedo decreases with distance to the center of tibetan plateau tp this may relate to the elevation of glacier for the speed of glacier retreat highly depends on air temperature 3 in the summer period albedo on most glaciers declines over the last 12years and it decreases much faster in southeastern tp than other regions for which air temperature overwhelms the black carbon concentration in addition the trend of glacier albedo in summer is greatly correlated with that of measured glacier mass balance which implies that the long term albedo datasets by remote sensing technology could be used to monitor and predict the change of glacier mass balance in the future 2013 john wiley sons ltd

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

retreating alpine glaciers increased melt rates due to accumulation of dust vadret da morteratsch switzerland the automatic weather station aws on the snout of the vadret da morteratsch switzerland has delivered a unique 12 year meteorological dataset from the ablation zone of a temperate glacier this dataset can be used to study multi annual trends in the character of the surface energy budget since 2003 there has been a substantial darkening of the glacier tongue due to the accumulation of mineral and biogenic dust the typical surface albedo in summer has dropped from 0 32 to 0 15 we have analysed the implications of the lowered albedo for the energy balance and the annual ablation for the 4 year period 2003 06 the decreased albedo caused an additional removal of about 3 5 m of ice calculations with an energy balance model show that the same increase in ablation is obtained by keeping the ice albedo fixed to 0 32 and increasing the air temperature by 1 7 k our analysis confirms that for retreating glaciers the deposition of dust from exposed side moraines on the glacier surface constitutes an important feedback mechanism the mineral dust stimulates the growth of algae lowers the surface albedo enhances the melt rates and thereby facilitates the further retreat of the glacier snout

albedo variations and the impact of clouds on glaciers in the chilean semi arid andes albedo variations are presented at two on glacier sites in the semi arid andes chile with 3 years of continuous measurements although 2 km apart and at similar elevations the sites show significantly different albedo cycles whereas toro 1 exhibits a clear seasonal cycle guanaco reveals a more complicated pattern as exposed ice can occur in any month of the year daily albedo values are as low as 0 18 for debris covered toro 1 while minima are higher on guanaco 0 38 a method is presented to discern cloud free from cloudy conditions using measured incoming shortwave radiation only a cloud climatology is provided showing very low cloudiness values we see that effective cloud cover relates inversely to cloud occurrence i e either more but thin or fewer but thick clouds the cloud free diurnal albedo cycle is pronounced with lowest values around noon clouds increase albedo by 0 04 as a median hourly value and 0 20 for the 95 quantile there is a positive relationship between effective cloud cover and resulting albedo rise calculations as to whether the diurnal albedo cycle or the effect of clouds on albedo should be considered in energy balance estimations show that the former is necessary whereas the latter can be neglected in the semi arid andes

fault reactivation analysis using microearthquake clustering based on signal to noise weighted waveform similarity the cluster formation of about 2000 induced microearthquakes mostly m l 2 is studied using a waveform similarity technique based on cross correlation and a subsequent equivalence class approach all events were detected within two separated but neighbouring seismic volumes close to the geothermal powerplants near landau and insheim in the upper rhine graben sw germany between 2006 and 2013 besides different sensors sampling rates and individual data gaps mainly low signal to noise ratios snr of the recordings at most station sites provide a complication for the determination of a precise waveform similarity analysis of the microseismic events in this area to include a large number of events for such an analysis a newly developed weighting approach was implemented in the waveform similarity analysis which directly considers the individual snrs across the whole seismic network the application to both seismic volumes leads to event clusters with high waveform similarities within short seconds to hours and long months to years time periods covering two magnitude ranges the estimated relative hypocenter locations are spatially concentrated for each single cluster and mirror the orientations of mapped faults as well as interpreted rupture planes determined from fault plane solutions depending on the waveform cross correlation coefficient threshold clusters can be resolved in space to as little as one dominant wavelength the interpretation of these observations implies recurring fault reactivations by fluid injection with very similar faulting mechanisms during different time periods between 2006 and 2013

mass balance model parameter transferability on a tropical glacier we explore the small scale spatial and temporal transferability of model parameters between two points in the ablation zone of tropical glaciar shallap cordillera blanca peru 9 s 77 w 4800 m a s l in order to provide a robust assessment of the performance of a process based glacier mass balance model relative surface height change is calculated at hourly time steps and cumulative values are compared to surface height measurements made at irregular intervals 14 64 days over the course of two continuous hydrological years august 2006 august 2008 best performing parameter combinations were determined for each point from the outcome of 1000 model simulations for which parameters were varied randomly within a defined range with these parameter combinations measurements for a specific location and time span are well reproduced transferring the parameter combination as optimized for one location to the other location in the ablation zone increases the errors of modeled cumulative mass balance by 5 1326 mm ice eq a 1 transferring the parameter combinations as optimized for one year to the other year increases the modeled errors in cumulative mass balance by 18 3179 mm ice eq a 1 model errors generally increase during periods with frequent snowfall and snow cover this could reflect either the inherent difficulty of modeling complex snow processes or the inability of the model to correctly capture the pattern of albedo evolution at this site the magnitude of errors associated with parameter transfer in space and time highlights the need for improving model performance for robust climatological and or hydrological analyses on tropical glaciers

radiative fluxes and their impact on the energy balance of the greenland ice sheet a meteorological experiment was carried out during the summer months of 1990 and 1991 near the mean equilibrium line altitude ela on the western slope of the greenland ice sheet eth camp 69 34 n 49 17 w 1155 m a s l as a part of the project the energy fluxes at the surface including all components of the radiation balance atmospheric profiles with a tower and radiosondes and the cloud conditions were investigated in detail results from the radiative fluxes are compared with observations made at other locations in order to derive general characteristics of the radiation conditions on the greenland ice sheet and their relation to the climate of the ice sheet at eth camp albedo values obtained at ground level 2 m and from a high tower 27 m are similar during the melt season late may to mid august and slightly different during pre and post melt seasons due to the interplay of inhomogeneous surface conditions and solar elevation during the melt period the decrease in global radiation due to increasing cloud amount is compensated for by an increase in longwave incoming radiation because of the steady values of longwave outgoing radiation net radiation at the surface is characterized mainly by the albedo and its variation the regional net radiation for summer months on the greenland ice sheet is determined mainly by three facts 1 a strong increase in albedo from the ablation area to the ela and a smaller increase from the ela to the accumulation area 2 a large increase in longwave outgoing radiation in the ablation area and at the ela in june and july compared to the accumulation area 3 a larger amount of cloud of the stratus type at lower areas

a study of ablation variations on the tongue of hintereisferner austrian alps austria here we discuss the interpretation of detailed ablation measurements on the tongue two profiles are considered one along the glacier axis and one across the glacier tongue at the crossing an energybalance station was operated providing the necessary meteorological data at all stakes the albedo was measured several times with a simple light weight instrument described separately in the appendix the absorption of solar radiation was calculated for all stake positions taking into account local albedo slope aspect and shading effects it appears that the differences in ablation can be explained almost entirely by the differences in surface albedo both along and across the glacier tongue

hydrometeorological relationships on haig glacier alberta canada we investigate the relationships between meteorological hydrological and glaciological data collected at haig glacier alberta canada for the 2002 and 2003 ablation seasons correlation lag cross correlation and multivariate regression analyses are employed to assess the seasonal evolution of relationships between temperature temperature residuals total daily radiation albedo accumulation area ratio aar and total daily discharge qi early season melt is temperature dependent when aar remains high and the hydraulic properties of the snowpack limit both diurnal discharge variability and a rapid hydrologic response as the melt season progresses a decreasing aar and ripening of the snowpack induce a glacier wide decrease in albedo and a structured radiation discharge response is observed radiation detrended temperature values offer modest improvements over physical temperature values in multivariate regression models estimating daily discharge values using a detrended temperature indexed melt model we assess the transport efficiency of the glacial hydrologic system through a comparison of total modelled daily melt and observed discharge transport efficiency values support the notion of a purge effect during freezing events and at the end of the ablation season and suggest that it is the evolution of the supraglacial drainage system that controls diurnal discharge variability

automatic methodology for mapping of coastal zones in video sequences abstract gathering precise and detailed geomorphological and dynamic information of coastal processes is increasingly required for environmental studies and coastal management policies as well traditional methods for in situ measurements or remote sensing monitoring by satellites or airbone imagery impose limitations and tradeoffs between image quality operational costs availability and negative environmental effects these limitations and tradeoffs restrict the kind of environmental studies that can be undertaken specifically when a high spatial and temporal resolution is required over wide geographical areas in the last decades video monitoring systems have demonstrated to be a cost effective alternative for this and other similar purposes notwithstanding that video processing is not fully mature in the context of environmental monitoring in general and thus most of the past and current efforts have been developed in an ad hoc basis this has the drawback that most available solutions are hardly useful in contexts different from their original setup in this work we develop an autonomous application for geographic feature extraction and recognition in coastal videos specifically we address the classification and feature measurement of multiple beach zones a topic addressed to a lesser extent by other projects the system is designed to be deployed in inexpensive off the shelf hardware and open source software development frameworks in a way such that the results can be easily replicated by other research groups the initial setup and calibration requires very simple supervision thus allowing the system to be used in a variety of coastal environments

areal melt and discharge modelling of storglaciaren sweden a grid based glacier melt and discharge model was applied to storglaciaren a small valley glacier 3 km 2 in northern sweden for the melt seasons of 1993 and 1994 the energy available for melt was estimated from a surface energy balance model using meteorological data collected by automatic weather stations on the glacier net radiation and the turbulent heat fluxes were calculated hourly for every grid point of a 30 m resolution digital terrain model using the measurements of temperature humidity wind speed and radiative fluxes on the glacier two different bulk approaches were used to calculate the turbulent fluxes and compared with respect to their impact on discharge simulations discharge of storglaciaren was simulated from calculated meltwater production and precipitation by three parallel linear reservoirs corresponding to the different storage properties of firn snow and ice the performance of the model was validated by comparing simulated discharge to measured discharge at the glacier snout depending on which parameterization of the turbulent fluxes was used the timing and magnitude of simulated discharge was in good agreement with observed discharge or simulated discharge was considerably underestimated in one year

climate sensitivity of storglaciaren sweden an intercomparison of mass balance models using era 40 re analysis and regional climate model data estimates of glacier contributions to future sea level rise are often computed from mass balance sensitivities derived for a set of representative glaciers our purpose is to investigate how mass b

variations of ablation albedo and energy balance at the margin of the greenland ice sheet kronprins christian land eastern north greenland a meteorological and glaciological experiment was carried out in july 1993 at the margin of the greenland ice sheet in kronprins christian land eastern north greenland within a small area about 100 m 2 daily measurements were made on ten ablation stakes fixed in light and dark ice and were compared to each other simultaneously the components of the energy balance including net radiation sensible heat flux latent heat flux and conductive heat flux in the ice were determined global radiation longwave incoming radiation and albedo were measured and longwave outgoing radiation was calculated by assuming that the glacier surface was melting sensible and latent heat fluxes were calculated from air temperature humidity and wind speed conductive heat flux in the ice was estimated by temperature profile measurements in the uppermost ice layer net radiation is the major source of ablation energy and turbulent fluxes are smaller energy sources by about three times while heat flux into the ice is a substantial heat sink reducing energy available for ice melt albedo varies from 0 42 to 0 56 within the experimental site and causes relatively large differences in ablation at stakes close to each other small scale albedo variations should therefore be carefully sampled for large scale energy balance calculations

distributed mass balance modelling on two neighbouring glaciers in ortles cevedale italy from 2004 to 2009 a 6 year application of an enhanced temperature index mass balance model to careser and la mare glaciers eastern italian alps is presented the two glaciers exhibit very different characteristics and a comprehensive dataset of distributed mass balance measurements was used to test the model performance the model was run using meteorological data acquired outside the glaciers the work was focused on two main aspects 1 the development of a morphological redistribution procedure for snow and 2 the comparison of three different melt algorithms proposed in the literature the results show that the simple method proposed for snow redistribution can greatly improve simulation of winter balance and further improvements would be achievable by collecting data on inaccessible and high altitude areas all three melt formulations displayed a good skill level and very similar results in modelling the mass balance distribution over glacier areas with slightly better results from a multiplicative algorithm in capturing the vertical balance gradient the simulation errors are related to aspect and elevation and tend to be spatially aggregated some assumptions concerning the spatial and temporal distribution of air temperature and incoming solar radiation although reasonable and widely used in the literature may be responsible for this aggregation hence there is a need to further investigate the processes that regulate the distribution of melt energy and that appear to control the current deglaciation phase in this area

energy and mass balance of zhadang glacier surface central tibetan plateau climate variables that control the annual cycle of the surface energy and mass balance on zhadang glacier in the central tibetan plateau were examined over a 2 year period using a physically based energy balance model forced by routine meteorological data the modelled results agree with measured values of albedo incoming longwave radiation surface temperature and surface level of the glacier for the whole observation period the radiation component dominated 82 the total surface energy heat fluxes this was followed by turbulent sensible 10 and latent heat 6 fluxes subsurface heat flux represented a very minor proportion 2 of the total heat flux the sensitivity of specific mass balance was examined by perturbations of temperature 1 k relative humidity 20 and precipitation 20 the results indicate that the specific mass balance is more sensitive to changes in precipitation than to other variables the main seasonal variations in the energy balance were in the two radiation components net shortwave radiation and net longwave radiation and these controlled whether surface melting occurred a dramatic difference in summer mass balance between 2010 and 2011 indicates that the glacier surface mass balance was closely related to precipitation seasonality and form proportion of snowfall and rainfall

a simple energy balance model to calculate ice ablation at the margin of the greenland ice sheet apres avoir etabli les relations donnees climatiques taux d enlevement de la glace dans 2 glaciers du groenland un modele simple de bilan energetique est effectue pour calculer le taux d enlevement de la glace aux bordures du glacier

sensitivity of mass balance and equilibrium line altitude to climate change in the french alps assessment of the sensitivity of surface mass balance and equilibrium line altitude ela to climate change is crucial for simulating the future evolution of glaciers such an assessment has been carried out using an extensive dataset comprising numerous measurements of snow accumulation and snow and ice ablation made on four french glaciers over the past 16 years winter mass balance shows a complicated pattern with respect to altitude with no clear linear relationship although the ratios of winter mass balance to valley precipitation differ considerably from site to site they are relatively constant over time relationships between snow ice ablation and temperature are stable with no link with altitude the mean snow and ice positive degree day pdd factors are 0 003 and 0 0061 m w e c 1 d 1 this analysis shows that at a given site ablation depends mainly on the amount of snow precipitation and on cumulative pdds the sensitivity of annual ablation to temperature change increases almost linearly from 0 25 m w e c 1 at 3500 m to 1 55 m w e c 1 at 1650 m ela sensitivity to temperature change was found to range from 50 to 85 m c 1

near surface hydraulic conductivity of northern hemisphere glaciers the hydrology of near surface glacier ice remains a neglected aspect of glacier hydrology despite its role in modulating meltwater delivery to downstream environments to elucidate the hydrological characteristics of this near surface glacial weathering crust we describe the design and operation of a capacitance based piezometer that enables rapid economical deployment across multiple sites and provides an accurate high resolution record of near surface water level fluctuations piezometers were employed at 10 northern hemisphere glaciers and through the application of standard bail recharge techniques we derive hydraulic conductivity k values from 0 003 to 3 519 m day 1 with a mean of 0 185 0 019 m day 1 these results are comparable to those obtained in other discrete studies of glacier near surface ice and for firn and indicate that the weathering crust represents a hydrologically inefficient aquifer hydraulic conductivity correlated positively with water table height but negatively with altitude and cumulative short wave radiation since the last synoptic period of either negative air temperatures or turbulent energy flux dominance the large range of k observed suggests complex interactions between meteorological influences and differences arising from variability in ice structure and crystallography our data demonstrate a greater complexity of near surface ice hydrology than hitherto appreciated and support the notion that the weathering crust can regulate the supraglacial discharge response to melt production the conductivities reported here coupled with typical supraglacial channel spacing suggest that meltwater can be retained within the weathering crust for at least several days not only does this have implications for the accuracy of predictive meltwater run off models but we also argue for biogeochemical processes and transfers that are strongly conditioned by water residence time and the efficacy of the cascade of sediments impurities microbes and nutrients to downstream ecosystems because continued atmospheric warming will incur rising snowline elevations and glacier thinning the supraglacial hydrological system may assume greater importance in many mountainous regions and consequently detailing weathering crust hydraulics represents a research priority because the flow path it represents remains poorly constrained

a distributed surface energy balance model for a small valley glacier i development and testing for haut glacier d arolla valais switzerland this paper describes the development and testing of a distributed surface energy balance model used to calculate rates of surface melting at haut glacier d arolla valais switzerland the model uses a digital elevation model dem of the glacier surface and surrounding topography together with meteorological data collected at a site in front of the glacier to determine hourly or daily totals of the energy balance components and hence of melting over the entire surface of the glacier with a spatial resolutio of 20 m the model can also be used to determine temporal and spatial variations in snow depth snow line position and glacier surface albedo calculations from the model are compared with observations made along the glacier centre line in 1990 and in general the model performs very well the correlation coefficients between calculated and measured snow line elevation albedo and ablation are 0 99 0 85 and 0 81 respectively the main source of error between modelled and measured values of these variables is probably inadequacies in the parameterization of albedo used in the model

the surface energy balance of an active ice covered volcano villarrica volcano southern chile the energy balance of bare snow and tephra covered ice near the glacier equilibrium line elevation on villarrica volcano southern chile was investigated during 2004 and 2005 combining meteorological surface temperature and ablation measurements with energy balance modelling a tephra thermal conductivity of 0 35 w m 1 k 1 and a critical tephra thickness of 0 1 m tephra windblown tephra impurities lowered snow albedo but increased snowmelt by only an estimated 0 28 m w e over the same period the net mass balance impact of supraglacial tephra at villarrica volcano is therefore positive as thick ash and lapilli mantle most of the glacier ablation zones probably reducing annual ablation by several metres w e in the accumulation seasons frequent melting events were recorded with modelled daily snowmelt rates of up to 50 mm w e

melt and surface sublimation across a glacier in a dry environment distributed energy balance modelling of juncal norte glacier chile previous estimates of melt and surface sublimation on glaciers of the subtropical semiarid andes 29 34 s have been obtained at few specific locations but it is not clear how ablation components vary across the entire extent of a glacier in this dry environment here we simulate the distributed energy and mass balance of juncal norte glacier 33 s during a 2 month summer period forcing fields of near surface air temperature and wind speed are generated using two methods accounting for the main physical processes that shape their spatial variations simulated meteorological variables and ablation agree well with observations on the glacier tongue and reveal complex patterns of energy and mass fluxes ablation decreases from 70 mm w e d 1 at the low albedo glacier terminus 3000 m where almost 100 of total ablation corresponds to melt to 75 of total ablation our simulations provide the first glacier scale estimates of ablation components on a glacier in the study region and better reproduce the observed and expected spatial variations of melt and surface sublimation in comparison with more simple assumptions such as linear gradients and uniform wind speeds

neglecting ice atmosphere interactions underestimates ice sheet melt in millennial scale deglaciation simulations dynamic and thermodynamic interactions between the atmosphere and underlying ice sheets are generally not represented in the traditional one way boundary condition forcing used to drive ice sheet models this shortcoming is investigated through a series of idealized millennial scale deglaciation simulations designed to isolate the mechanisms regulating the deglaciation timescale of the laurentide ice sheet sensitivity experiments indicate that the conventional use of one way non interactive atmospheric forcing fields leads to an unrealistically insensitive melt response in the ice sheet model even when atmospheric carbon dioxide is set to modern preindustrial levels and earth s angle of obliquity is set to its early holocene value a more realistic deglaciation timescale is obtained only through the application of a new two way interactive asynchronous ice atmosphere coupling scheme and a seasonal ice albedo parameterization that accounts for the observed darkening of ice in the moist summertime ablation zone

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

sediment export transient landscape response and catchment scale connectivity following rapid climate warming and alpine glacier recession abstract in the face of rapid climate warming rapid glacier recession should lead to a marked increase in the spatial extent of the paraglacial zone in glaciated drainage basins the extent of the paraglacial zone has been well established to be transient but there are very few studies of this transient response and what it means for sediment export there is good reason to expect that glacier recession could increase basin scale sediment connectivity as sediment becomes less dependent on glacier surface transport proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity by using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment sand and gravel export from a basin with a rapidly retreating valley glacier the haut glacier d arolla from 1977 to 2014 modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity indeed there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area more recently we were able to show possible temperature control on sediment export which may only have become apparent because of the progressive development of better sediment connectivity however whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached we identified two possible examples of why first gullying was also accompanied by the sediment accumulation at the base of moraines that was too coarse to be transported by the proglacial stream maintaining disconnection of the upper basins second the sediment capacity ratio appeared to be elevated during periods of more rapid retreat and we attribute this to the importance of a continued supply of unworked glacial till before fluvial reworking and sorting of freshly exposed sediment increased the resistance of sediment to entrainment and hence export rates thus the transient geomorphic response of glaciated basins to glacier recession may involve negative feedbacks that can reduce the extent to which increases in connectivity elsewhere in the basin lead to increased sediment export

spatial and temporal variations of the surface albedo and other factors influencing urumqi glacier no 1 in tien shan china glacier albedo controls the surface energy budget the variability of which affects the glacier surface melt rate and in turn impacts the mass balance of the glacier during 2013 and 2014 spatial and temporal variations of albedo were investigated using 18 landsat images of urumqi glacier no 1 factors influencing these spatiotemporal profiles were analyzed an established retrieval process including geolocation radiometric calibration atmospheric topographic and anisotropic correction and narrow to broadband conversion was applied for the first time to landsat 8 images differences between landsat image derived albedo values and albedo values measured using a handheld spectroradiometer ranged from 0 024 to 0 049 spatial and temporal variations of surface albedo were significant especially in the ablation area the variability of the values of ice albedo ranged from 0 06 to 0 44 due to topographic effects and light absorbing impurities the results suggest that this retrieval method can be used to investigate the spatial and temporal variability of surface albedo from landsat 8 images on mountain glaciers moreover as constant albedo values for ice and snow cannot be assumed the distribution of albedo was not completely dependent on altitude under conditions of more intense ablation and by reason of light absorbing impurities during the melt season

2 m temperatures along melting mid latitude glaciers and implications for the sensitivity of the mass balance to variations in temperature in calculations of the variation in the 2 m temperature along glaciers the lapse rate is generally assumed to be constant this implies that the ratio of changes in the 2 m temperature above a glacier to changes in the temperature outside the thermal regime of that glacier climate sensitivity is equal to 1 however data collected during the ablation season on several mid latitude glaciers show that this sensitivity is smaller than 1 the lowest measured value 0 3 was obtained on the tongue of the pasterze a glacier in austria the measured temperature distribution along the pasterze cannot be described by a constant lapse rate either however there is almost a linear relationship between potential temperature and the distance along die glacier this paper introduces a simple analytical thermodynamic glacier wind model which can be applied to melting glaciers and which explains the observed climate sensitivities and temperature distributions much better than calculations based on a constant lapse rate this way of modelling the 2 m temperatures has implications for the sensitivity of the surface mass balance to atmospheric warming outside the thermal regime of the glacier the magnitude of this sensitivity is computed with a surface energy balance model applied to the pasterze when a constant lapse rate is used instead of the proposed glacier wind model to compute changes in the 2 m temperature along the glacier the negative change in mass balance due to 1 c warming is overestimated by 22

climate sensitivity of glaciers in southern norway application of an energy balance model to nigardsbreen hellstugubreen and alfotbreen three glaciers in southern norway with very different massbalance characteristics are studied with an energy balance model of the ice snow surface the model simulates the observed mass balance profiles in a satisfactory way and can thus be used with some confidence in a study of climate sensitivity calculated changes in equilibrium line altitude for a 1 k temperature increase are 110 108 and 135 in for nigardsbreen hellstugubreen and alfotbreen respectively the corresponding changes in mass balance averaged over the entire glacier area are 0 88 0 715 and 1 11 in year water equivalent runs with an ice flow model for nigardsbreen to which calculated mass balance profiles are imposed predict that the front will advance by 3 km for a 1 k cooling and will retreat by as much as 6 5 km for a 1 k warming the response to a 10 increase in precipitation would be a 2 km advance of the snout whereas a 4 km retreat is predicted for a 10 decrease this large sensitivity as compared to many other glaciers is to a large extent due to the geometry of nigardsbreen

the surface albedo of the greenland ice sheet satellite derived and in situ measurements in the sondre stromfjord area during the 1991 melt season the temporal and spatial variation in the surface albedo of the greenland ice sheet during the ablation season of 1991 is investigated the study focuses on an area east of sondre stromfjord measuring 200 km by 200 km and centred at 67 5 n 48 13 w the analysis is based on satellite radiance measurements carried out by the advanced very high resolution radiometer avhrr the broad band albedo is estimated from the albedos in channel 1 visible and channel 2 near infrared the results are calibrated with the surface albedo of sea and dry snow satellite derived albedos are compared with gimex ground measurements at three stations there is a high degree of consistency in temporal variation at two of the three stations large systematic differences are attributed to albedo variations on subpixel scale in the course of the ablation season four zones appear each parallel to the ice edge it is proposed that these are in order of increasing altitude i clean and dry ice ii ice with surface water iii superimposed ice and iv snow an extensive description of these zones is given on the basis of the situation on 25 july 1991 zones i iii and iv reveal fairly constant albedos 0 46 0 65 and 0 75 on average whereas zone ii is characterised by an albedo minimum 0 34 survey of the western margin of the greenland ice sheet up to 71 n shows that the zonation occurs between 66 and 70 n

self similarity in glacier surface characteristics catchment wide information on glacier snow cover depth surface albedo and surface roughness is important input data for distributed models of glacier energy balance in this study we investigate the small scale mm to 100 m spatial variability in these properties with a view to better simulating this variability in such models data were collected on midre lovenbreen a 6 km 2 valley glacier in northwest svalbard the spatial variability of all three properties was found to be self similar over the range of scales under investigation snow depth and albedo exhibit a correlation length within which measurements were spatially autocorrelated late winter and summer properties of snow depth differed with smaller depths in summer due to melt and shorter correlation lengths similar correlation lengths for snow depth and surface albedo may suggest that snow depth variation is an important control on the small scale spatial variability of glacier surface albedo for surface roughness the data highlight a possible problem in energy balance studies which use microtopographic surveys to calculate aerodynamic roughness in that the scale of the measurements made affects the calculated roughness value this suggests that further investigations of the relationships between surface form and aerodynamic roughness of glacier surfaces are needed

visible and near infrared reflectivity during the ablation period on peyto glacier alberta canada models for calculating glacier mass balance are sensitive to surface reflectivity variation fieldwork carried out on peyto glacier alberta canada contributes to the data set available for ice reflectivity parameterization in such models hemispherical reflectivity in the visible and near infrared parts of the solar spectrum was obtained for rock snow and three contrasting glacier surfaces to examine temporal and spatial variations glacier ice near infrared reflectivity displays only minor spatial variation 0 12 0 17 in comparison with the visible range 0 23 0 40 the latter being influenced primarily by surface impurity content surface roughness is of minor importance compared with impurities temporal variation of reflectivity was weak at all glacier ice and rock locations slight variations observed were due to changes in either solar zenith angle or cloud amount snow reflectivity displayed pronounced diurnal asymmetry and a larger response to cloud cover the minimal temporal variation in glacier ice reflectivity simplifies its parameterization this behaviour is additionally useful for satellite based measurements of the reflectivity field on larger glaciers as images obtained within a 6 h window centred on solar noon are likely to yield values which are within 2 3 of daily mean values

spatial and temporal variations in albedo on storglaciaren sweden extensive albedo data from storglaciaren sweden during nine summers are analyzed focusing on the effect of surface slope on measurements and on the influence of clouds on albedo of both snow and ice surfaces on clear sky days albedo continuously dropped throughout the day by 0 3 when derived from measurements in a horizontal plane over the slightly sloping surface when we correct for the tilt effect over frozen surfaces the apparent decrease in albedo largely disappeared while over melting surfaces it became significantly less pronounced this emphasizes the need to correct horizontally measured data for slope when they are used for example as ground truth for satellite derived albedo or in high resolution glacier melt runoff models albedo varied by 0 1 due to cloud fluctuations to quantify cloud effects albedo changes between successive half hourly and daily data were regressed against corresponding changes in cloudiness expressed by the ratio of global radiation to top of atmosphere solar radiation the resulting relationship over snow explains 66 of oberved albedo changes using hourly and 4 using daily time steps over ice the corresponding values arc 28 and 0 hence cloudiness is a dominating factor in determining short term variability of albedo over snow whereas over ice the observed large day to day variability 20 is mainly attributed to changes in the physical characteristics of the weathering crust results suggest that cloud effects should be incorporated into models treating snow and ice surfaces separately

a 1 year record of global radiation and albedo in the ablation zone of morteratschgletscher switzerland we analyse data on solar radiation measured with an automatic weather station on morteratschgletscher switzerland for the period 1 october 1995 30 september 1996 the station is in the lower ablation zone due to shading by surrounding mountains and atmospheric attenuation only 49 of the annual extraterrestrial irradiance mean 292 w m 2 reaches the glacier surface about 48 of this is absorbed at the surface mean 79 w m 2 annual albedo of 0 53 we present a simple albedo scheme for use in glacier mass balance models we fit the model to the 1 year dataset by optimizing five control parameters optimal values in brackets albedo of snow 0 75 albedo of firn 0 53 albedo of ice 0 34 e folding constant for effect of ageing on snow albedo 21 9 days and e folding constant for effect of snow depth on albedo 3 2 cm the input consists of daily albedo snow depth and dates of snowfall events the correlation coefficient between observed and simulated albedo is 0 931 the corresponding rms difference being 0 067

mass balance gradients and climatic change it is generally assumed that the mass balance gradient on glaciers is more or less conserved under climatic change in studies of the dynamic response of glaciers to climatic change one of the following assumptions is normally made i the mass balance perturbation is independent of altitude or ii the mass balance profile does not change it simply shifts up and down observational evidence for such an approach is not convincing on some glaciers the inter annual changes in mass balance seem to be independent of altitude on others not at all moreover it is questionable whether inter annual variation can be projected on different climatic states to see what a physical approach might contribute we developed an altitude dependent mass balance model it is based on the energy balance of the ice snow surface where precipitation is included in a parameterized form and numerical integrations are done through an entire balance year with a 30 min time step atmospheric temperature snowfall and atmospheric transmissivity for solar radiation are all dependent on altitude so a mass balance profile can be calculated slope and exposure of the ice snow surface are taken into account and the effects of these parameters studied in general the calculations were done for 100 m elevation intervals climatological data from the sonnblick observatory austria 3106 m a s l and from vent 2000 m a s l oetztal alps austria served as input for a number of runs simulation of the mass balance profiles for hinterseisferner north easterly exposure and kesselwandferner southeasterly exposure yields reasonable results the larger balance gradient on kesselwandferner is produced by the model so exposure appears to be an important factor here sensitivity of mass balance profiles to shading effects different slope and exposure are systematically studied another section deals with the sensitivity to climatic change perturbations of air temperature cloudiness albedo and precipitation are imposed to see their effects on the mass balance profiles the results clearly show that in general mass balance perturbations depend strongly on altitude they generally increase down glacier and are not always symmetric about the reference state for typical climatic conditions in the alps we found that a 1 k temperature change leads to a change in equilibrium line altitude of 130 m three factors contribute to this large value turbulent heat flux longwave radiation from the atmosphere and fraction of precipitation falling as snow here the albedo feed back increases the sensitivity in a significant way

temporal and spatial variations in spectral reflectance and characteristics of surface dust on gulkana glacier alaska range spectral reflectances in the visible to near infrared wavelength range 350 1050 nm were measured on the surface of gulkana glacier alaska range alaska usa at six different elevations from may to september 2001 the measurements showed variable spectral reflectances on the glacier surface and the spectra changed over time and elevation the spectra in may were those of a typical wet snow surface the reflectance ranged approximately from 0 4 to 0 8 and generally decreased as the wavelength increased as snowmelt proceeded the reflectance gradually fell and specific absorptions appeared in the spectrum at wavelength ranges of 400 600 and 670 680 nm corresponding to a red snow surface due to snow algal bloom as the ice surface was exposed the spectrum finally shifted to a lower 0 1 0 4 and flat reflectance curve typical of an ice surface contaminated with dust analyses of the dust on the glacier surface showed that its quantity and characteristics changed spatially and seasonally and were correlated with spectral albedo the results showed that the temporal and spatial variations in spectral reflectance on this glacier are due not only to physical properties of the glacier surface but also to biogenic materials on the surface e g red colored snow algal cells and cryoconite

rapid quantification of cryoconite granule geometry and in situ supraglacial extents using examples from svalbard and greenland supraglacial dust cryoconite is an important but poorly understood component of the glacial system there is a lack of primary data on cryoconite form extent and dynamics here we present a suite of rapid low cost methodologies for quantification of granule geometry and supraglacial cryoconite coverage using image data captured by commercially available digital cameras we develop robust transferable protocols for analysis of 1 cryoconite granule geometry major axis feret diameter circularity 2 centimetre metre scale supraglacial extent m2 cryoconite m 2 surface and 3 temporal change in supraglacial extent at hourly intervals over several days image processing methodologies were developed using the public domain software imagej manual supervised controls were used to estimate sources of error and measurements then automated using simple scripting tools macros fully automated processing successfully identified 90 of a sample of isolated granules ranging between 2 5 and 39 2 mm with uncertainties of 20 particle sphericity inferred from circularity decreased as particle size increased supraglacial cryoconite extent was obtained with a mean uncertainty of 37 and 22 for data from field sites in greenland and svalbard respectively these methods will facilitate acquisition and analysis of datasets for cryoconite across a range of spatial scales supporting research into cryoconite impacts on supraglacial hydrological connections nutrient and carbon cycling and initiation of primary succession in deglaciating environments

interdecadal variability of degree day factors on vestari hagafellsjokull langjokull iceland and the importance of threshold air temperatures the skill of degree day glacier melt models is highly dependent on the choice of degree day factor ddf which is often assumed to remain constant in time here we explore the validity of this assumption in a changing climate for two locations on vestari hagafellsjokull 1979 2012 using a surface energy balance seb approach that isolates the effect of changes in the prevailing weather on the ddf at lower elevation we observe stable ddf during the period of study however at higher elevation ddf is noted to be more variable and a statistically significant downward trend is observed this is found to result from an inappropriate threshold air temperature t crit from which to initiate the positive degree day sum and is removed by setting t crit to 1 83 c rather than the usual value of 0 c used in degree day melt models the stationarity of ddf once t crit is adjusted contradicts previous research and lends support to the use of constant ddf for projecting future glacier melt optimizing t crit also improves the skill of melt simulations at our study sites this research thus highlights the importance of t crit for both melt model performance and the evaluation of ddf stationarity in a changing climate

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

a 5 year record of surface energy and mass balance from the ablation zone of storbreen norway a 5 year record of data from an automatic weather station aws operating in the ablation zone of storbreen norway has been used to calculate the local surface energy and mass balance the aws observations cover five mass balance years with an unusually strong mass deficit on storbreen the average energy flux q contributing to melt for the period 2001 06 is 113wm 2 of this the net shortwave radiation flux is the dominant contributor 92wm 2 followed by the sensible heat flux 20 wm 2 and the latent heat flux 9 w m 2 the net longwave radiation 6w m 2 and the subsurface heat flux 2 w m 2 contribute negatively to the budget net radiation thus produces 76 of the melt while the turbulent fluxes and the subsurface heat flux produce 24 of the total melt the seasonal mean incoming shortwave radiation is remarkably constant between the years whereas variations in temperature and reflected shortwave radiation albedo explain most of the interannual variation in melt the modelled ablation compares well with the measured ablation from stake readings the sensitivity of the energy balance model was examined by varying the surface roughness length of momentum and the sensitivity of the calculated melt by perturbations of temperature wind speed and relative humidity