how do geomorphic effects of rainfall vary with storm type and spatial scale in a post fire landscape abstract in post fire landscapes increased runoff and soil erosion can cause rapid geomorphic change we examined how different types of rainfall events in 2013 affected hillslope scale erosion and watershed scale channel change in two 14 16 km 2 watersheds within the 2012 high park fire burn area in northern colorado usa the first set of rainfall events was a sequence of 12 short spatially variable summer convective rain storms and the second was a 200 mm week long storm in september we compared rainfall characteristics hillslope sediment yields stream stage and channel geometry changes from the summer storms to those from the september storm the summer storms had a wide range of rainfall intensities and each storm produced erosion primarily in one study watershed the september storm rainfall had less spatial variability covered both watersheds and its total rainfall depth was 1 5 to 2 5 times greater than the total summer rainfall because rainfall intensities were highest during some summer storms average hillslope sediment yields were higher for summer storms 6 mg ha 1 than for the september storm 3 mg ha 1 maximum storm rainfall intensities were good predictors of hillslope sediment yield but sediment yield correlated most strongly with total depths of rainfall exceeding 10 30 mm h 1 intensity thresholds the combined summer storms produced relatively small changes in mean channel bed elevation and cross section area with no clear pattern of incision or aggradation in contrast the sustained rain across the entire study area during the september storm led to extensive upstream incision and downstream aggradation because of different spatial coverage of storms summer storms produced more total hillslope erosion whereas the september storm produced the greatest total channel changes at both scales high intensity rainfall above a threshold was responsible for inducing most of the geomorphic change

after six decades of monitoring glacier mass balance we still need data but it should be richer data this paper reviews data on glacier mass balance together with extra metadata on topography and climate to put the data into context the 2007 intergovernmental panel on climate change ipcc estimates of global average glacier mass balance may not be much different from simple averages a more mathematically correct approach is to analyse long and continuous mass balance series measured in different regions but there are few long series and they do not cover the globe in any representative way however 30 year series from 30 glaciers confirm a recent 1996 2005 trend to very negative mass balance after two decades of nearly zero mass balance climate data from a global gridded climatology are applied to datasets for global glacier cover for 318 glaciers with mass balance data for at least 1 year and for 30 glaciers with 30 year series of measurements results show that mean precipitation is relatively low in the global glacier cover dataset and much higher for the observed glaciers this shows that current mass balance measurements are biased towards wetter conditions than are typical for global glacier cover we urgently need to find better ways of analysing sparse datasets with complex spatial and temporal patterns like the present mass balance dataset

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

topographic controls on the surface energy balance of a high arctic valley glacier 1 this paper presents the results of a distributed two dimensional surface energy balance model used to investigate the spatial and temporal variations in the surface energy balance of midre lovenbreen a small valley glacier in northwest spitsbergen svalbard over the summer of 2000 we utilize high resolution airborne lidar data to derive a digital elevation model of the glacier and surrounding topography on which a surface energy balance is computed driven by meteorological data obtained from a meteorological station located on the glacier and a synoptic station maintained at the nearby ny alesund research base given the high resolution topographic data we focus particularly on whether the long duration of sunshine at high latitudes compensates for the higher solar zenith angles on the season long energy balance and whether shading by the surrounding topography plus glacier surface slope and aspect play an increased role in the patterns of solar radiation receipt and hence melt over the glacier surface the model results are validated using a combination of mass balance data from the glacier measured surface lowering at the glacier meteorological station and by comparing a derived energy balance component from the model with a measured energy flux overall the model performance is very good glacier topography is found to play a fundamental role in determining the surface energy balance topographic shading slope and aspect and correction of the surface albedo for high solar zenith angles are found to play a crucial role in determining spatial patterns of surface energy balance and therefore melt

moments of catchment storm area the portion of a catchment covered by a stationary rainstorm is modeled by the common area of two overlapping circles given that rain occurs within the catchment and conditioned by fixed storm and catchment sizes the first two moments of the distribution of the common area are derived from purely geometrical considerations the variance of the wetted fraction is shown to peak when the catchment size is equal to the size of the predominant storm the conditioning on storm size is removed by assuming a probability distribution based upon the observed fractal behavior of cloud and rainstorm areas

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

dem analyses and morphotectonic interpretation the plio quaternary evolution of the eastern ligurian alps italy abstract the ligurian alps italy straddle a complex and ill defined tectonic transition that accommodates eurasia adria shortening driving concurrent growth of the western alps and northern apennines we focus on the plio quaternary landscape evolution of the eastern part of the ligurian alps with the goal of defining the active tectonics through an analysis of topography drainage networks and river long profiles the ligurian alps have a steep seaward facing escarpment with topographic features reminiscent of the geomorphic markers preserved on both actively uplifting coastlines and passive margins for example there are seaward facing benches that are thought to be uplifted marine terraces common to active margins but the drainage divide of the seaward escarpment shows clear evidence of recent northward migration into the po foreland a process consistent with escarpment retreat characteristic of passive or subsiding margins this study explores the active tectonics consistent with these diverse landscape evolution pathways our analysis reveals that rock type strongly throttles the development of topographic relief drainage networks and northward migration of the drainage divide however we also identify segments of the escarpment that indicate recent base level falls through an analysis of modeled channel steepness and comparison with mean hillslope gradient the base level falls are consistent with numerous barbed tributaries that are best explained as recent stream captures no significant correlation among the stream captures at the drainage divide suspected marine terraces at the coast ligurian sea bathymetry and active seismicity indicates that the escarpment is the footwall of a segmented normal fault this normal fault is embedded in a regionally subsiding margin where actively uplifting segments lead to a straightened pinned drainage divide whereas relatively inactive segments permit divide migration into the footwall block these results are broadly consistent with rock uplift increasing eastward toward genova across the long suspected alps apennine sestri voltaggio fault zone they highlight the respective roles of legacy structures rock type and localized rock uplift in constructing a landscape in an otherwise extending and subsiding crustal retrowedge of an active subduction plate boundary

suitability of a constant air temperature lapse rate over an alpine glacier testing the greuell and bohm model as an alternative near surface air temperature typically measured at a height of 2 m is the most important control on the energy exchange and the melt rate at a snow or ice surface it is distributed in a simplistic manner in most glacier melt models by using constant linear lapse rates which poorly represent the actual spatial and temporal variability of air temperature in this paper we test a simple thermodynamic model proposed by greuell and bohm in 1998 as an alternative using a new dataset of air temperature measurements from along the flowline of haut glacier d arolla switzerland the unmodified model performs little better than assuming a constant linear lapse rate when modified to allow the ratio of the boundary layer height to the bulk heat transfer coefficient to vary along the flowline the model matches measured air temperatures better and a further reduction of the root mean square error is obtained although there is still considerable scope for improvement the modified model is shown to perform best under conditions favourable to the development of katabatic winds few clouds positive ambient air temperature limited influence of synoptic or valley winds and a long fetch but its performance is poor under cloudy conditions

transmission of solar radiation through clouds on melting glaciers a comparison of parameterizations and their impact on melt modelling we explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the swiss alps we also look at the rationale behind some of the most commonly used approaches and explore the relationship between cloud transmittance and several standard meteorological variables the 2 m air temperature diurnal range is the best predictor of variations in cloud transmittance however linear and exponential parameterizations can only explain 30 50 of the observed variance in computed cloud transmittance factors we examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature index model the melt model performance decreases when modelled radiation is used the reduction being due to an underestimation of incoming solar radiation on clear sky days the model works well under overcast conditions we also seek alternatives to the use of in situ ground data however outputs from an atmospheric model 2 2 km horizontal resolution do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations conversely the correct definition of overcast conditions is important

temperature and precipitation climate at the equilibrium line altitude of glaciers expressed by the degree day factor for melting snow several authors relate accumulation or precipitation at the glacier equilibrium line altitude ela to summer mean temperature using exponential or power law functions i analyze the accumulation temperature relation at the ela with a degree day model using data from the 1992 paper by a ohmura and others the dataset includes estimates at the ela of winter balance and of winter balance plus summer precipitation which represent respectively low and high estimates of annual accumulation which is seldom measured the ohmura dataset only lists summer mean temperature but i recover monthly temperatures for the whole year for 66 of the glaciers by assuming sinusoidal temperature variation through the year and using annual temperature range from a gridded climatology monthly degree day sums are then estimated from monthly mean temperature and summed to give annual totals so degree day factors for melting snow at the ela are obtained the degree day factors fall close to those reported in the literature for glacier snowmelt with averages of 3 5 1 4 and 4 6 1 4 mm d 1 k 1 for low and high accumulation estimates on the 66 glaciers the degree day model gives a family of accumulation temperature curves that depend upon the annual temperature range representing the contrast between maritime and continental climates

volume change of mccall glacier arctic alaska usa 1956 2003 a long history of research documents that mccall glacier arctic alaska usa continues to lose mass at a rate that is likely increasing with time we present a photo comparison 1958 2003 that visually documents these volume changes along with survey measurements that quantify these losses measurements of longitudinal profiles initially acquired from airborne laser altimetry and repeated by ground based surveys indicate that the areally averaged rate of thinning increased between 1956 93 and 1993 2002 from 0 35 0 07 m a 1 to 0 47 0 03 m a 1 respectively total volume loss was 8 3 107 1 7 107 m3 and 2 7 107 0 2 107 m3 all in water equivalent for these two time periods these profiles also indicate that a 1 km stretch of the mid ablation area is behaving differently from this trend with a rate of thinning that is not changing with time lastly we present a comparison of several methods for calculating volume change and assess their relative errors

surface temperature lapse rates over complex terrain lessons from the cascade mountains lapse rates of 3 9 5 2 c km 1 substantially smaller than the often assumed 6 5 c km 1 the data sets show similar seasonal and diurnal variability with lapse rates smallest 2 5 3 5 c km 1 in late summer minimum temperatures and largest 6 5 7 5 c km 1 in spring maximum temperatures geographic windward versus lee side differences in lapse rates are found to be substantial using a simple runoff model we show the appreciable implications of these results for hydrological modeling

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

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

sensitivity of net mass balance estimates to near surface temperature lapse rates when employing the degree day method to estimate glacier melt glacier mass balance models that employ the degree day method of melt modeling are most commonly driven by surface air temperatures that have been downscaled over the area of interest using digital elevation models and assuming a constant free air lapse rate that is often taken to be the moist adiabatic lapse rate malr 6 58 ck m 1 air temperature lapse rates measured over melting glacier surface are however consistently less steep than free air values and have been shown to vary systematically with lower tropospheric temperatures in this study the implications of including a variable near surface lapse rate in a 26 year 1980 2006 degree day model simulation of the surface mass balance of devon ice cap nunavut canada are examined and compared with estimates derived from surface air temperatures downscaled using a constant near surface lapse rate equal to the measured summer mean 4 98 ck m 1 and the malr our results show that degree day models are highly sensitive to the choice of lapse rate when compared with 23 years of surface mass balance measurements from the northwest sector of the ice cap model estimates are significantly better when surface air temperatures are downscaled using a modeled daily lapse rate rather than a constant lapse equal to either the summer mean or the malr

spatial and temporal variability of air temperature on a melting glacier atmospheric controls extrapolation methods and their effect on melt modeling juncal norte glacier chile 1 temperature data from three automatic weather stations and twelve temperature loggers are used to investigate the spatiotemporal variability of temperature over a glacier its main atmospheric controls the suitability of extrapolation techniques and their effect on melt modeling we use data collected on juncal norte glacier central chile during one ablation season we examine temporal and spatial variability in lapse rates lrs together with alternative statistical interpolation methods the main control over the glacier thermal regime is the development of a katabatic boundary layer kbl katabatic wind occurs at night and in the morning and is eroded in the afternoon lrs reveal strong diurnal variability with steeper lrs during the day when the katabatic wind weakens and shallower lrs during the night and morning we suggest that temporally variable lrs should be used to account for the observed change they tend to be steeper than equivalent constant lrs and therefore result in a reduction in simulated melt compared to use of constant lrs when extrapolating from lower to higher elevations in addition to the temporal variability the temperature elevation relationship varies also in space differences are evident between local lrs and including such variability in melt modeling affects melt simulations extrapolation methods based on the spatial variability of the observations after removal of the elevation trend such as inverse distance weighting or kriging do not seem necessary for simulations of gridded temperature data over a glacier

area perimeter relation for rain and cloud areas following mandelbrot9s theory of fractals the area perimeter relation is used to investigate the geometry of satellite and radar determined cloud and rain areas between 1 and 1 2 x 106square kilometers the data are well fit by a formula in which the perimeter is given approximately by the square root of the area raised to the power d see equation in the pdf where d is interpreted as the fractal dimension of the perimeter it is concluded that rain and cloud perimeters are fractals they have no characteristic horizontal length scale between 1 and 1000 kilometers

model study of the spatial distribution of the energy and mass balance of morteratschgletscher switzerland to investigate the spatial distribution of the energy and mass balance fluxes of a glacier a two dimensional mass balance model was developed and applied to morteratschgletscher switzerland the model is driven by meteorological input from four synoptic weather stations located in the vicinity of morteratschgletscher the model results were compared to observations made on the glacier the calculated mean specific mass balance is 0 47 m w e for 1999 and 0 23 m w e for 2000 net shortwave radiation shows a minimum at around 3350 m a s l due to the effects of shading slope aspect reflection from the slopes and obstruction of the sky ignoring these effects results in a 37 increase in the annual incoming shortwave radiation on the glacier causing 0 34 m w e more ablation a 1 c change in the air temperature results in a shift of 0 67 m w e in the mean specific mass balance while altering the precipitation by 10 causes a change of 0 17 m w e

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

strain rates in northwestern italy from spatially smoothed seismicity 1 this work presents seismic strain rate maps for the western alps and northern apennines northern italy as derived from an earthquake catalog collecting both historical and instrumental data strain rates are calculated on the basis of the rate of seismic moment release using the anderson method unlike previous applications which determined the total strain rate associated with specific seismogenic sources we have employed an innovative zoneless approach based on a spatially smoothed seismicity method in addition a monte carlo simulation procedure is applied to allow for uncertainty in the input data e g magnitude to moment conversion seismogenic thickness maximum earthquake magnitude strain rate maps are developed by summing the moments of the earthquakes reported in the catalog and by using two different earthquake recurrence relations our results indicate that deformation rates are quite high ranging from about 2 to 12 10 9 yr 1 in the northern apennines and from 0 5 to 6 10 9 yr 1 in the western alps these values however are 1 order less than those derived from global positioning system measurements suggesting that a portion of the recent deformation in northwestern italy is related to aseismic processes the discrepancies between seismic and geodetic strain rates may also indicate that the record of seismicity may not provide a sufficient time window for assessment of secular rates of moment release or secular deformation rates and rates of recurrence of large magnitude earthquakes in the study area

on hydrologic similarity 1 derivation of the dimensionless flood frequency curve the problem of flood frequency similarity among river basins is analyzed by deriving a scale independent dimensionless flood frequency curve the model is formulated using dimensionless rainfall inputs and a dimensionless basin response function for the rainfall intensity the probability distribution for dimensionless areal rainfall is derived and depends upon a geoclimatic scaling factor which is a function of the basin size and the rainfall areal correlation structure rainfall duration is scaled by a characteristic basin time this same parameter is used to develop a dimensionless geomorphologic unit hydrograph the derived dimensionless flood frequency curve can be used to further understand the variability of flood statistics within a contiguous area and to group stations for regional flood frequency analysis using statistical techniques

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

a derived flood frequency distribution using horton order ratios a flood frequency distribution is derived from assumed climatic distributions and the geomorphologic unit hydrograph guh model of catchment response the derived distribution is tested on two appalachian mountain catchments and shows good agreement with historical data because the guh is rooted in catchment shape and geomorphology this derived frequency distribution may be a promising vehicle for studying the effect of catchment shape on flood frequency characteristics furthermore it is felt that the question of catchment homogeneity and similarity necessary for regional flood estimation can also be studied through the guh derived flood distribution

hintereisferner austria mass balance reconstruction and numerical modelling of the historical length variations in this study an attempt is made to simulate the historical length variations of hintereisferner austria key elements in the model are 1 reconstruction of the local climate vent 2 multiple linear regression analysis between measured climate and mass balance variations 3 reconstruction of the mass balance with 1 and 2 4 a one dimensional numerical ice flow model forced by the mass balance history

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

degree day glacier mass balance modelling with applications to glaciers in iceland norway and greenland a degree day glacier mass balance model is applied to three glaciers in iceland norway and greenland for which detailed mass balance measurements are available over a period of several years model results are in good agreement with measured variations in the mass balance with elevation over the time periods considered for each glacier in addition the model explains 60 80 of the year to year variance in the elevation averaged summer season mass balance measurements on the glaciers using a single parameter set for each glacier the increase in ablation on the glaciers due to a warming of 2 c is predicted to range from about 1 m w e year 1 at the highest elevations to about 2 5 m w e year 1 at the lowest elevations predicted changes in the winter balance measured between fixed date are relatively small except at the lowest elevations on the icelandic and norwegian glaciers where the winter balance is significantly reduced equilibrium line altitudes are raised by 200 300 m on the icelandic and norwegian glaciers except at the highest elevations the winter balance of the icelandic and norwegian glaciers is predicted to decrease even if the warming is accompanied by a 10 increase in the precipitation no firm evidence of a climate related variation in the degree day factors or in the temperature lapse rate on the same glacier could be found the model furthermore reproduces large variations in the mass balance with elevation and from year to year on each glacier using the same parameter set we assume therefore that these parameters will not change significantly for the climate scenarios considered here

air temperature distribution and energy balance modelling of a debris covered glacier near surface air temperature is an important determinant of the surface energy balance of glaciers and is often represented by a constant linear temperature gradients tgs in models spatiotemporal variability in 2 m air temperature was measured across the debris covered miage glacier italy over an 89 d period during the 2014 ablation season using a network of 19 stations air temperature was found to be strongly dependent upon elevation for most stations even under varying meteorological conditions and at different times of day and its spatial variability was well explained by a locally derived mean linear tg mg tg of 0 0088 c m 1 however local temperature depressions occurred over areas of very thin or patchy debris cover the mg tg together with other air tgs extrapolated from both on and off glacier sites were applied in a distributed energy balance model compared with piecewise air temperature extrapolation from all on glacier stations modelled ablation using the mg tg increased by 4 using the environmental lapse rate ice melt under thick debris was relatively insensitive to air temperature while the effects of different temperature extrapolation methods were strongest at high elevation sites of thin and patchy debris cover

le plio quaternaire de la mer ligure epaisseurs et conditions d accumulation abstract a map of the thickness of plio quaternary sediments in the ligurian sea is presented here made from the data of seismic reflection methods collected by the istituto di geologia of genoa and the istituto di oceanologia of naples an explanation is derived from this map regarding the conditions under which the accumulation of the so called sediments was made these conditions are mainly determined by the neo tectonics the submarine erosion and the mass gravity transport

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

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

baffin island snow extent sensitivity insights from a regional climate model 1 recent modeling efforts suggest that the little ice age lia onset could be explained by a series of four large decadally spaced volcanic eruptions at that time glaciers on baffin island advanced and did not retreat until the past century perhaps due to arctic and north atlantic ocean sea ice feedbacks to try to determine what parameters sustain snow cover we investigate the relative impacts of changes in radiation and advection on minimum summer snow extent over baffin island we used the weather research and forecasting wrf model to run eight 6 month long april september 10 km resolution simulations in which we varied boundary condition temperatures solar radiation and sea ice cover although the control run underestimated cloud cover and thus produced an exaggerated diurnal 2 m temperature cycle the relative changes of snow extent show that wrf accurately simulates snow expansion into the same regions as during the lia with an average temperature decrease from current temperatures by 3 9 1 1 k it only requires one season for the model to lower the snowline by comparable elevation changes seen during the descent into the lia wrf s maximum snow line sensitivity is 7 k km within the range of the typically assumed lapse rate of 5 7 k km in the canadian arctic thus if a shift in the arctic climate greatly expanded sea ice coverage following large volcanic eruptions this would have been enough to perpetuate an ice sheet on baffin island throughout the lia

centreline and cross glacier air temperature variability on an alpine glacier assessing temperature distribution methods and their influence on melt model calculations the spatio temporal distribution of air temperature over mountain glaciers can demonstrate complex patterns yet it is often represented simplistically using linear vertical temperature gradients vtgs extrapolated from off glacier locations we analyse a network of centreline and lateral air temperature observations at tsanteleina glacier italy during summer 2015 on average vtgs are steep 1 but they are shallow under warm ambient conditions when the correlation between air temperature and elevation becomes weaker published along flowline temperature distribution methods explain centreline observations well including warming on the lower glacier tongue but cannot estimate lateral temperature variability application of temperature distribution methods improves simulation of melt rates rmse in an energy balance model by up to 36 compared to the environmental lapse rate extrapolated from an off glacier station however results suggest that model parameters are not easily transferable to glaciers with a small fetch without recalibration such methods have potential to improve estimates of temperature across a glacier but their parameter transferability should be further linked to the glacier and atmospheric characteristics furthermore cold spots which can be 2 c cooler than expected for their elevation whose occurrence is not predicted by the temperature distribution models are identified at one quarter of the measurement sites

aerodynamic stability and turbulent sensible heat flux over a melting ice surface the greenland ice sheet the turbulent sensible heat flux to a melting ice surface is calculated from wind speed and air temperature at 2 m over the ice surface assuming a certain wind profile with the appropriate surface roughness the aerodynamic stability of the boundary layer over melting ice is examined by comparing sensible heat fluxes for logarithmic and log linear wind profiles where the logarithmic profile is strictly valid only for neutral conditions increasing stability reduces the sensible heat flux to the glacier surface and introduces a non linear relation between heat flux and air temperature the stability effect is greatest at low wind speeds and fairly small at the high wind speeds that are common over the ice sheet earlier estimates of ablation by energy balance modelling may be too large due to neglect of stability but this was almost offset by using a surface roughness that was too small the log linear wind profile should be used in future energy balance models to take account of stability but more research is needed on the parameters of the profile as well as on the surface roughness

modeling 2 m air temperatures over mountain glaciers exploring the influence of katabatic cooling and external warming air temperature is one of the most relevant input variables for snow and ice melt calculations however local meteorological conditions complex topography and logistical concerns in glacierized regions make the measuring and modeling of air temperature a difficult task in this study we investigate the spatial distribution of 2 m air temperature over mountain glaciers and propose a modification to an existing model to improve its representation spatially distributed meteorological data from haut glacier d arolla switzerland place canada and juncal norte chile glaciers are used to examine approximate flow line temperatures during their respective ablation seasons during warm conditions off glacier temperatures well above 0 c observed air temperatures in the upper reaches of place glacier and haut glacier d arolla decrease down glacier along the approximate flow line at juncal norte and haut glacier d arolla an increase in air temperature is observed over the glacier tongue while the temperature behavior over the upper part can be explained by the cooling effect of the glacier surface the temperature increase over the glacier tongue may be caused by several processes induced by the surrounding warm atmosphere in order to capture the latter effect we add an additional term to the greuell and bohm gb thermodynamic glacier wind model for high off glacier temperatures the modified gb model reduces root mean square error up to 32 and provides a new approach for distributing air temperature over mountain glaciers as a function of off glacier temperatures and approximate glacier flow lines

climate variability and glacier reaction in the austrian eastern alps a carefully homogenized climate dataset is used to interpret glacier behaviour in the austrian alps periods of glacier advance are generally more maritime and cooler with reduced sunshine duration and increased precipitation sum during the ablation period periods of retreat are associated with a more continental warmer climate with increased sunshine duration and reduced precipitation sum three recent sub periods of austrian glacier behaviour are documented by direct measurement of glacier mass balance before 1965 more negative 1965 81 more positive since 1982 more negative a long term mass balance series in the eastern part of the austrian alps parameterized by snow depth measurements indicates very clearly that periods of more negative mass balance have a higher correlation to summer air temperature and a lower correlation to winter accumulation periods of more positive mass balance are highly correlated to winter accumulation and only slightly correlated to summer temperature the positive mass balance period 1965 81 is also characterized by negative north atlantic oscillation index values which caused an increased meridional circulation mode resulting in a northwesterly to northerly precipitation regime during winter

comparison of the meteorology and surface energy fluxes of debris free and debris covered glaciers in the southeastern tibetan plateau knowledge of debris free and debris covered glaciers is important for understanding the varying response of glaciers to climate change measurements at the debris free parlung no 4 glacier and the debris covered 24 k glacier in the southeastern tibetan plateau were carried out to compare the meteorology and surface energy fluxes and to understand the factors controlling the melting process the meteorological comparisons displayed temporally synchronous fluctuations in air temperature relative humidity and incoming longwave radiation l in but notable differences in precipitation incoming shortwave radiation s in and wind speed under the prevailing regional precipitation and debris conditions more l in 42 w m 2 was supplied from warmer and more humid air and more s in 58 w m 2 was absorbed at the 24 k glacier the relatively high energy supply led mainly to an increased energy output via turbulent heat fluxes and outgoing longwave radiation rather than glacier melting beneath the thick debris the sensitivity experiment showed that melt rates were sensitive to energy supply at debris thicknesses similar to 10 cm in contrast energy supply to the parlung no 4 glacier mainly resulted in snow ice melting the magnitude of which was significantly influenced by energy supplied by s in and the sensible heat flux

partial area coverage distribution for flood frequency analysis in arid regions convective rainfalls of high intensity are largely responsible for most large floods occurring in arid regions convective storms are limited in size and rarely cover an entire basin therefore flood frequency is affected by the distribution of storm coverage c which is the fraction of basin area upon which rainfall occurs analytical probability density function pdf estimates of partial storm coverage are presented as a function of basin area sc and the probability distribution function for storm radius rs conditional pdfs for the covered area fraction c given the storm radius f c rs are obtained as a compound distribution with finite probability for maximum coverage and continuous density for smaller values the conditionality assumption is removed by assuming an exponential storm radius marginal distribution to obtain the catchment coverage pdf this pdf is compound with discrete probability for complete catchment coverage p c 1 and a continuous function for partial overlap the continuous function combines a weibull pdf and linear functions of c both p c 1 and f c depend on the average catchment to storm radius ratio the distribution explains the partial coverage data for the walnut gulch basin in arizona departures were observed however for slightly less than complete coverage namely for 0 9 c 1 a conceptual event classification and a method were designed to include partial coverage effects on flood frequency distribution

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

elevational changes in meteorological variables along a midlatitude glacier during summer during the summer of 1994 a glaciometeorological experiment was carried out on the pasterze a glacier in austria this paper reports on the data from six energy balance stations ranging in altitude from 2075 to 3225 m above sea level asl the wind regime was dominated by the glacier wind on the tongue directional constancies ranged between 0 94 and 0 97 mean 2 m wind speed and specifie humidity were almost constant along the glacier the variation in the 2 m temperature along the glacier cannot be described by the usually assumed constant decrease with elevation on the tongue the 2 m temperature even increased with elevation a much better description of the temperature distribution is given by a linear relation between the potential temperature and the distance along the flow line this can be understood from a simple thermodynamic analysis of the glacier wind layer it is further shown that changes in clear sky global radiation with elevation are due mainly to changes in local albedo and relief and hardly at all to changes in absolute optical path length and atmospheric water vapor and aerosol content on the tongue the laterally averaged ice albedo is almost constant with elevation the flux of incoming long wave radiation during clear sky conditions at u2 2310 m asl was 48 w m2 higher than the flux at u5 3225 m asl on average more than half of the difference was due to systematic differences in the shape of the temperature profile probably the inversion depth is larger at u2 the rest can be ascribed to higher 2 m temperatures and larger amounts of upper hemisphere slopes at u2 the distributions of the meteorological variables and the parameterizations described in this paper might be incorporated in surface energy balance models designed to simulate the surface mass balance

derivation of melt factors from glacier mass balance records in western canada melt factors for snow k s and ice k i were derived from specific mass balance data and regionally interpolated daily air temperature series at nine glaciers in the western cordillera of canada fitted k s and k i were relatively consistent across the region with mean values standard deviations of 3 04 0 38 and 4 59 0 59 mm d 1 c 1 respectively the interannual variability of melt factors was investigated for two long term datasets calculated annually snow and ice melt factors were relatively stable from year to year standard deviations for snowmelt factors were 0 48 17 and 0 42 18 at peyto and place glaciers respectively while standard deviations of ice melt factors were 1 17 25 and 0 81 14 while fitted values of k s are comparable to those presented in previous observational and modeling studies fitted k i are substantially and consistently lower across the region fitted melt factors were sensitive to the choice of lapse rate used in the air temperature interpolation melt factors fitted to mass balance data from a single site place glacier provided reasonable summer balance predictions at most other sites representing both maritime and continental climates although there was a tendency for under prediction at several sites the combination of regionally interpolated air temperatures and a degree day model appears capable of generating first order estimates of regional summer balance which can provide a benchmark against which to judge the predictive ability of more complex e g energy balance models applied at a regional scale mass balance sensitivity analyses indicate that a temperature increase of 1 k will increase summer ablation in the region by 0 51 m w e a 1 on average

variability of air temperature over a debris covered glacier in the nepalese himalaya estimates of melt from debris covered glaciers require distributed estimates of meteorological variables and air temperature in particular meteorological data are scarce for this environment and spatial variability of temperature over debris is poorly understood based on multiple measurements of air and surface temperature from three ablation seasons 2012 14 we investigate the variability of temperature over lirung glacier nepal in order to reveal how air temperature is affected by the debris cover and improve ways to extrapolate it we investigate how much on glacier temperature deviates from that predicted from a valley lapse rate lr analyse on glacier lrs and test regression models of air temperature and surface temperature air temperature over the debris covered glacier tongue is much higher than what a valley lr would prescribe so an extrapolation from off glacier stations is not applicable an on glacier lr is clearly defined at night with strong correlation but not during the day when the warming debris disrupts the elevation control an alternative to derive daytime air temperature is to use a relationship between air and surface temperature as previously suggested we find strong variability during daytime that should be accounted for if these regressions are used for temperature extrapolation

air temperature variability in a high elevation himalayan catchment air temperature is a key control of processes affecting snow and glaciers in high elevation catchments including melt snowfall and sublimation it is therefore a key input variable to models of land surface atmosphere interaction despite this importance its spatial variability is poorly understood and simple assumptions are made to extrapolate it from point observations to the catchment scale we use a dataset of 2 75 years of air temperature measurements from may 2012 to november 2014 at a network of up to 27 locations in the langtang river nepal catchment to investigate air temperature seasonality and consistency between years we use observations from high elevations and from the easternmost section of the basin to corroborate previous findings of shallow lapse rates seasonal variability is strong with shallowest lapse rates during the monsoon season diurnal variability is also strong and should be taken into account since processes such as melt have a pronounced diurnal variability use of seasonal lapse rates seems crucial for glacio hydrological modelling but seasonal lapse rates seem stable over the 2 3 years investigated lateral variability at transects across valley is high and dominated by aspect with south facing sites being warmer than north facing sites and deviations from the fitted lapse rates of up to several degrees local factors e g topographic shading can reduce or enhance this effect the interplay of radiation aspect and elevation should be further investigated with high elevation transects

a large scale lateral spreading its genesis and quaternary evolution in the coastal sector between cogoleto and varazze liguria italy abstract the results of a study carried out on a coastal area of central western liguria northern italy where metamorphosed basic and ultrabasic rocks outcrop are presented the study indicates that a wide area 16 km 2 was involved in a large scale deep seated gravitational slope deformation dsgsd this movement has special features related to the lithology and structure of the involved rock mass to the plio quaternary uplifting and brittle tectonics affecting an area where a paleosurface was recognised and to the continental shelf dynamics the particular geometry of the dsgsd was recognised on the basis of detailed analyses of the above mentioned aspects due to its characteristics the deep seated deformation can be classified as a lateral spreading the current altitude of the pliocene marine clay outcrops and their deposition bathymetry allowed estimation of the uplift rate of the coastal area the altitudinal variations of an ancient marine terrace which was displaced by the dsgsd were used to reconstruct the chronology of the gravitational movement a final issue concerns the very large scale and the particular kind of phenomenon both of which are certainly new in liguria