a spatially distributed model for the dynamic prediction of sediment erosion and transport in mountainous forested watersheds 1 erosion and sediment transport in a temperate forested watershed are predicted with a new sediment model that represents the main sources of sediment generation in forested environments mass wasting hillslope erosion and road surface erosion within the distributed hydrology soil vegetation model dhsvm environment the model produces slope failures on the basis of a factor of safety analysis with the infinite slope model through use of stochastically generated soil and vegetation parameters failed material is routed downslope with a rule based scheme that determines sediment delivery to streams sediment from hillslopes and road surfaces is also transported to the channel network a simple channel routing scheme is implemented to predict basin sediment yield we demonstrate through an initial application of this model to the rainy creek catchment a tributary of the wenatchee river which drains the east slopes of the cascade mountains that the model produces plausible sediment yield and ratios of landsliding and surface erosion when compared to published rates for similar catchments in the pacific northwest a road removal scenario and a basin wide fire scenario are both evaluated with the model

regionally differentiated contribution of mountain glaciers and ice caps to future sea level rise the contribution to sea level rise from mountain glaciers and ice caps has grown over the past decades a projection of their melting during the twenty first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21 of their total global volume

transfer of basal sliding variations to the surface of a linearly viscous glacier on etudie pour une plaque a faces paralleles d epaisseur h et de viscosite lineaire l effet en surface des fluctuations de la vitesse de derapage

routing graded sediments in streams applications a one dimensional numerical model has been tested in simulating the movement of well graded sediments through a stream reach the model is applied to two laboratory flumes and two alluvial channel reaches found in the literature three of these examples are under steady state flow conditions and the other is under unsteady flow conditions in the unsteady flow situation the flow computations are done by using a water routing scheme based on the kinematic wave equations this scheme needs adjustment of one parameter the sediment model also needs adjustment of only one parameter which is the erodibility parameter the model predicts water and sediment discharges coming out of each reach size distributions of these transported materials size distributions of the bed material or the armor coat and changes in bed elevations comparisons of these predictions are made with the measurements available from these examples and are found to be promising

reconstruction of basal properties in ice sheets using iterative inverse methods inverse problems are used to estimate model parameters from observations many inverse problems are ill posed because they lack stability meaning it is not possible to find solutions that are stable with respect to small changes in input data regularization techniques are necessary to stabilize the problem for nonlinear inverse problems iterative inverse methods can be used as a regularization method these methods start with an initial estimate of the model parameters update the parameters to match observation in an iterative process that adjusts large scale spatial features first and use a stopping criterion to prevent the overfitting of data this criterion determines the smoothness of the solution and thus the degree of regularization here iterative inverse methods are implemented for the specific problem of reconstructing basal stickiness of an ice sheet by using the shallow shelf approximation as a forward model and synthetically derived surface velocities as input data the incomplete gauss newton ign method is introduced and compared to the commonly used steepest descent and nonlinear conjugate gradient methods two different stopping criteria the discrepancy principle and a recent improvement threshold are compared the ign method is favored because it is rapidly converging and it incorporates the discrepancy principle which leads to optimally resolved solutions

use of the she hydrological modelling system to investigate basin response to snowmelt at reynolds creek idaho abstract the first test of the snowmelt component of the systeme hydrologique europeen she hydrological modelling system is reported in which the she is used to simulate a 12 1 2 day period of snowmelt runoff for a 40 ha subbasin of the reynolds creek rangeland research basin in idaho the results show the she to be capable of successfully simulating hydrograph responses caused by snowmelt generated by heat inputs especially net radiation and sensible heat transfer the results also show how in the absence of previous field studies of basin response the she can be used to investigate different hypotheses of basin behaviour in this case four hypotheses of basin response are examined based on different representations of the soil permeability and subsurface flow pathways 1 impermeable frozen ground surface 2 fully permeable soil profile throughout the basin 3 reduced soil permeability away from the channel 4 rapid near channel subsurface response comparison of the measured and simulated hydrographs supports hypothesis 4 with a possible cause of the response being the rapid conversion of a near surface tension saturated capillary fringe into a pressure saturated zone by the infiltrating meltwater in the absence of direct measurements of net radiation and wind gradient indirectly derived values are used as input to the snowmelt component the implications which the uncertainty attached to these values holds for the simulation results is investigated in sensitivity tests which show that with sensible heat transfer forming the major heat flux to the snowpack greater uncertainty is introduced into the simulation results by the uncertainty in the wind gradient than by the uncertainty in the net radiation the snowmelt simulations are based on an energy budget option a test of a temperature based degree day option shows comparable accuracy but only through empirical fitting overall the study shows that a greater hydrological expertise is required in operating she type models compared with simpler models

theoretical limitations to englacial velocity calculations to study the dynamics of ice sheets and glaciers velocities at the bed of a glacier must be measured directly or calculated using data gathered from boreholes and surface surveys boreholes to the bed are expensive and time consuming to drill so the determination of basal velocity is almost exclusively by numerical inversion of velocities observed at the surface for non linearly viscous glaciers a perturbation analysis demonstrates that inversions for englacial velocities will magnify measurement errors at an exponential rate with depth the rate at which calculation errors grow is proportional to a lyapunov exponent a measure of information loss which is shown to be a simple linear function of spatial frequency with a coefficient depending on glen s flow law exponent n the coefficient decreases with increasing non linearity demonstrating that inversions with non linearly viscous ice have smaller calculation errors than inversions with linearly viscous ice in both the linear and nonlinear cases the lyapunov exponent and rate of error growth increases with decreasing wavelength which limits velocity calculations at the bed to wavelengths on the order of one ice thickness or greater this limitation is theoretical and cannot be countered by more accurate survey data or special numerical techniques

review of erosion dynamics along the major n s climatic gradient in chile and perspectives abstract chile is an elongated country running in a north south direction for more than 30 along a subduction zone its climate is progressively wetter and colder from north to south this particular geography has been used positively by a growing number of studies to better understand the relationships between erosion processes and climate land use slope tectonics volcanism etc here we review the erosion rates factors and dynamics over millennial to daily periods reported in the literature in addition 21 new catchment mean erosion rates suspended sediment and 10be are provided and previous suspended sediment derived erosion rates are updated a total of 485 local and catchment mean erosion rates are reported erosion rates vary between some of the smallest values on earth 10 5 mm a to moderate values 0 5 mm a compared to other active ranges this review highlights strong limitations concerning the quantification of local erosion factors because of uncertainties in sampling point location slope and rainfall data for the mean erosion rates e for the millennial and decennial catchments a model of the form e s 1 s 0 6 2 r with 0 3 0 8 accounts for 40 to 70 of the erosion variance confirming a primary role of slope s compared to precipitation rate r over this time scale over the long term this review points to the long 5 to 10 ma response time of rivers to surface uplift in north central arid chile over millennia data provide evidence for the progressive contribution of extreme erosion events to millennial averages for drier climates as well as the link between glacier erosion and glacier sliding velocity in this period of time a discrepancy exists between the long term offshore sedimentological record and continental decennial or millennial erosion data for which no single explanation appears still little information is available concerning the magnitude of variation of millennial erosion rates over centuries data show the variable role of groundwater in the dynamics of suspended load and document a decrease in erosion over hundreds of years probably associated with historical harvesting

the evolution of the patagonian ice sheet from 35 ka to the present day patice abstract we present patice a gis database of patagonian glacial geomorphology and recalibrated chronological data patice includes 58 823 landforms and 1 669 geochronological ages and extends from 38 s to 55 s in southern south america we use these data to generate new empirical reconstructions of the patagonian ice sheet pis and subsequent ice masses and ice dammed palaeolakes at 35 ka 30 ka 25 ka 20 ka 15 ka 13 ka synchronous with the antarctic cold reversal 10 ka 5 ka 0 2 ka and 2011 ad at 35 ka the pis covered of 492 6 x103 km2 had a sea level equivalent of 1 496 mm was 350 km wide and 2090 km long and was grounded on the pacific continental shelf edge outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams the pis reached its maximum extent by 33 28 ka from 38 s to 48 s and earlier around 47 ka from 48 s southwards net retreat from maximum positions began by 25 ka with ice marginal stabilisation then at 21 18 ka which was then followed by rapid irreversible deglaciation by 15 ka the pis had separated into disparate ice masses draining into large ice dammed lakes along the eastern margin which strongly influenced rates of recession glacial readvances or stabilisations occurred at least at 14 13 ka 11 ka 6 5 ka 2 1 ka and 0 5 0 2 ka we suggest that 20th century glacial recession a 1 is occurring faster than at any time documented during the holocene

a tutorial on the use of control methods in ice sheet modeling control methods are recommended as an efficient means to estimate undetermined physical parameters and boundary conditions and in so doing to improve the fidelity of a given ice sheet flow model to specific ice sheet velocity observations to accomplish this task the underlying dynamics of the model are inverted this permits model tuning adjustments to be represented explicitly in terms of model observation misfit

force budget i theory and numerical methods a practical method is developed for calculating stresses and velocities at depth using field measurements of the geometry and surface velocity of glaciers to do this it is convenient to partition full stresses into lithostatic and resistive components the horizontal gradient in vertically integrated lithostatic stress is the driving stress and it describes the horizontal action of gravity the horizontal resistive stress gradients describe the reactions resistive stresses are simply related to deviatoric stresses and hence to strain rates through a constitutive relation a numerical scheme can be used to calculate stresses and velocities from surface velocities and slope and from ice thickness there is no mathematical requirement that the variations in these quantities be small

thermoluminescence constraints on the metamorphic shock and brecciation history of basaltic meteorites abstract induced thermoluminescence measurements have been performed on eighteen eucrites thirteen howardites plus seven splits from the bholghati howardite six diogenites and fifteen mesosiderites in order to help clarify their metamorphic shock and brecciation history the tl sensitivities of the basaltic meteorites reflect their bulk composition and the effects of 1 igneous processes diogenites and mesosiderites and 2 the mixing of materials of different compositions e g diogenitic and eucritic during brecciation howardites can be observed two previously unclassified mesosiderites lew87006 and eet87500 are assigned to class a and b respectively on the basis of their tl sensitivities the eucrites show a 15 fold range of tl sensitivities which correlate with petrographie indicators of metamorphic intensity we therefore describe a petrologic type scale based on tl and petrographie evidence where the least metamorphosed eucrites are type 1 and most equilibrated are type 8 we see no evidence for two discrete metamorphic environments corresponding to the equilibrated and unequilibrated eucrites the temperature of the dominant tl peak observed for basaltic meteorites and experiments in which four eucrites with diverse petrographie properties were annealed at various temperatures in the laboratory suggests the metamorphic equilibration temperatures for most basaltic meteorites were 800 c this estimate is generally consistent with palaeotemperatures determined from two pyroxene olivine pyroxene and oxygen isotope equilibria assuming this temperature was typical of conditions during metamorphism then burial depths for type 5 eucrites were 350 m and

volume area scaling parameterisation of norwegian ice caps a comparison of different approaches over the recent decades glaciers have in general continued to lose mass causing surface lowering volume reduction and frontal retreat thus contributing to global sea level rise when making assessments of present and future sea level change and management of water resources in glaciated catchments precise estimates of glacier volume are important the glacier volume cannot be measured on every single glacier therefore the global glacier volume must be estimated from models or scaling approaches volume area scaling is mostly applied for estimating volumes of glaciers and ice caps on a regional and global scale by using a statistical theoretical relationship between glacier volume v and area a v ca for explanation of the parameters c and see eq 1 in this paper a two dimensional 2d glacier model has been applied on four norwegian ice caps hardangerjokulen nordre folgefonna sporteggbreen and vestre svartisen in order to obtain values for the volume area relationship on ice caps

the effect of forest cover on peak flow and sediment discharge an integrated field and modelling study in central southern chile an integrated field and modelling study was carried out on the 35 ha la reina catchment chile to test the hypothesis that the effect of forest cover on flood peaks becomes less important as the size of the hydrological event increases meteorological and discharge data were measured at the catchment before and after the pine plantation that covered 80 of the catchment area was logged analysis of the measured response of the catchment provides support for the hypothesis but is not conclusive therefore modelling of the catchment using 1000 years of generated rainfall data representative of the current conditions was carried out for the forested and logged states the simulations show that the absolute difference in discharge between the two cases remains approximately constant as the discharge increases thus as a percentage of discharge it decreases this relative convergence appears to become significant at return periods of greater than approximately 10 years tests with different hypothetical soil depths for the forested and logged catchments show an absolute convergence in discharge between the two cases for shallow soils and no convergence for deep soils sediment transport simulations show that forest cover provides a clear benefit in protecting the soil from erosion copyright 2010 john wiley sons ltd

stress gradient coupling in glacier flow i longitudinal averaging of the influence of ice thickness and surface slope for a glacier flowing over a bed of longitudinally varying slope the influence of longitudinal stress gradients on the flow is analyzed by means of a longitudinal flow coupling equation derived from the vertically cross sectionally integrated longitudinal stress equilibrium equation by an extension of an approach originally developed by budd 1968 linearization of the flow coupling equation by treating the flow velocity u vertically averaged ice thickness h and surface slope in terms of small deviations u h and a from overall average datum values u 0 h 0 and 0 results in a differential equation that can be solved by green s function methods giving u x as a function of h x and x x being the longitudinal coordinate the result has the form of a longitudinal averaging integral of the influence of local h x and x on the flow u x u x u0 2l l 0 ln n nh n l exp x x l dx where the integration is over the length l of the glacier the operator specified deviations from the datum state and the term on which it operates which is a function of the integration variable x represents the influence of local h x x and channel shape factor x at longitudinal coordinate x on the flow u at coordinate x the influence being weighted by the influence transfer function exp x x l in the integral the quantity l that appears as the scale length in the exponential weighting function is called the longitudinal coupling length it is determined by rheological parameters via the relationship l 2h n n 3n where n is the flowlaw exponent n the effective longitudinal viscosity and n the effective shear viscosity of the ice profile n is an average of the local effective viscosity n over the ice cross section and n 1 is an average of n 1 that gives strongly increased weight to values near the base theoretically the coupling length l is generally in the range one to three times the ice thickness for valley glaciers and four to ten times for ice sheets for a glacier in surge it is even longer l 12h it is distinctly longer for non linear n 3 than for linear rheology so that the flow coupling effects of longitudinal stress gradients are markedly greater for non linear flow the averaging integral indicates that the longitudinal variations in flow that occur under the influence of sinusoidal longitudinal variations in h or with wavelength are attenuated by the factor 1 1 2 l 2 relative to what they would be without longitudinal coupling the short intermediate and long scales of glacier motion raymond 1980 over which the longitudinal flow variations are strongly partially and little attenuated are for 2l 2l 20l and 20l for practical glacier flow calculations the exponential weighting function can be approximated by a symmetrical triangular averaging window of length 4l called the longitudinal averaging length the traditional rectangular window is a poor approximation because of the exponential weighting the local surface slope has an appreciable though muted effect on the local flow which is clearly seen in field examples contrary to what would result from a rectangular averaging window tested with field data for variegated glacier alaska and blue glacier washington the longitudinal averaging theory is able to account semi quantitatively for the observed longitudinal variations in flow of these glaciers and for the representation of flow in terms of effective surface slope values exceptions occur where the flow is augmented by large contributions from basal sliding in the ice fall and terminal zone of blue glacier and in the reach of surge initiation in variegated glacier the averaging length 4l that gives the best agreement between calculated and observed flow pattern is 2 5 km for variegated glacier and 1 8 km for blue glacier corresponding to l h 2 in both cases if l varies with x but not too rapidly the exponential weighting function remains a fairly good approximation to the exact green s function of the differential equation for longitudinal flow coupling in this approximation l in the averaging integral is l x but is not a function of x effects of longitudinal variation of l are probably important near the glacier terminus and head and near ice falls the longitudinal averaging formulation can also be used to express the local basal shear stress in terms of longitudinal variations in the local stope stress with the mediation of longitudinal stress gradients

global distributions of glacier properties a stochastic scaling paradigm many problems in global climate and earth systems science require knowledge of regional or global scale distributions of glacier properties which includes mass balance ice velocity flux thickness volume and surface area among others with roughly 160 000 glaciers worldwide obtaining information on the global probability distributions of most ice properties is expensive and often infeasible only surface area distributions are relatively easy to measure either by direct observation or remote sensing while other properties are difficult to observe this work shows that scaling relationships from the continuum dynamics of ice can link the distribution of surface areas to the global and regional distributions of any other continuum property some data inventories already exist for constructing reasonable distributions of glacier sizes and this analysis presents theoretical arguments based on glacier network topologies similar in concept to river networks to suggest a power law times an exponential distribution of surface areas in agreement with the data therefore by using existing data or the theoretical distributions of surface areas specific distributions for other glacier properties in any region of the world can be constructed as an example predictions up to a scaling constant are made for the distribution of glacier volumes characteristic thicknesses characteristic velocities and characteristic response times in the alps

characteristics of sediment discharge in the subarctic yukon river alaska abstract the characteristics of sediment discharge in the yukon river alaska were investigated by monitoring water discharge water turbidity and water temperature the river transported sediment 90 wt or more consists of silt and clay grain size 62 5 m which probably originated in the glacier covered mountains mostly in the alaska range for early june to late august 1999 we continuously measured water turbidity and temperature near the estuary and in the middle of yukon river by using self recording turbidimeters and temperature data loggers the water turbidity ppm was converted to suspended sediment concentration ssc mg l of river water using a relation between simultaneous turbidity and ssc at each of the two sites and then the suspended sediment discharge approximately equal to water discharge times ssc was numerically obtained every 1 or 2 h it should be noted that the sediment discharge in the yukon river is controlled by ssc rather than water discharge as a result a peak sediment discharge occurred in mid or late august by local sediment runoffs due to glacier melt or glacier melt plus rainfall while a peak water discharge was produced by snowmelt in late june or early july application of the extended shields diagram indicates that almost all the river transported sediments are under complete suspension

multi scale permeability estimation for a tropical catchment physically based and spatially distributed modelling of catchment hydrology involves the estimation of block or whole hillslope permeabilities invariably these estimates are derived by calibration against rainfall runoff response rarely are these estimates rigorously compared with parameter measurements made at the small scale this study uses a parametrically simple model topmodel and an uncertainty framework to derive permeability at the catchment scale the utility of expert knowledge of the internal catchment dynamics i e extent of saturated area in constraining parameter uncertainty is demonstrated model derived estimates are then compared with core based measurements of permeability appropriately up scaled the observed differences between the permeability estimates derived by the two methods might be attributed to the role of intermediate scale features natural soil pipes an alternative method of determining block permeabilities at the intermediate or hillslope scale is described this method uses pulse wave tests and explicitly incorporates the resultant effects of phenomena such as soil piping and kinematic wave migration the study aims to highlight issues associated with parameterizing or validating distributed models rather than to provide a definitive solution the fact that the permeability distribution within the borneo study catchment is comparatively simple assists the comparisons the field data were collected in terrain covered by equatorial rainforest combined field measurement and modelling programmes are rare within such environments

a consensus estimate for the ice thickness distribution of all glaciers on earth knowledge of the ice thickness distribution of the world s glaciers is a fundamental prerequisite for a range of studies projections of future glacier change estimates of the available freshwater resources or assessments of potential sea level rise all need glacier ice thickness to be accurately constrained previous estimates of global glacier volumes are mostly based on scaling relations between glacier area and volume and only one study provides global scale information on the ice thickness distribution of individual glaciers here we use an ensemble of up to five models to provide a consensus estimate for the ice thickness distribution of all the about 215 000 glaciers outside the greenland and antarctic ice sheets the models use principles of ice flow dynamics to invert for ice thickness from surface characteristics we find a total volume of 158 41 103 km3 which is equivalent to 0 32 0 08 m of sea level change when the fraction of ice located below present day sea level roughly 15 is subtracted our results indicate that high mountain asia hosts about 27 less glacier ice than previously suggested and imply that the timing by which the region is expected to lose half of its present day glacier area has to be moved forward by about one decade the ice volume of glaciers outside the greenland and antarctic ice sheets totals about 158 000 km3 with about 27 less ice in high mountain asia than thought according to multiple models that estimate ice thickness from surface characteristics

induced thermoluminescence as a method for dating recent volcanism eastern snake river plain idaho usa the induced thermoluminescence properties of 24 samples of basalts from volcanoes in the eastern snake river plain idaho were measured as part of an investigation into the possibility of using this technique for dating purposes the volcanic flows sampled ranged in age from 2200 years to 400 000 years the tl sensitivity values obtained i e maximum induced tl normalized to that of the dhajala meteorite where dhajala 1000 ranged from 1 6 0 3 to 226 15 and showed a correlation between log tl and age with an r2 value of 0 47 thus tl sensitivity values correlate with age in the manner expected although there is a high level of scatter we discuss various mechanisms for the correlation and scatter particularly 1 the role of primary igneous processes and secondary solid state processes 2 composition of the plagioclase feldspar 3 weathering the induced tl signal from feldspars the mineral responsible for the tl is strongly dependent on their composition and correcting for this improved the correlation r2 0 7 variations in primary feldspar are affecting the data but we find no evidence that weathering of the samples is important further work is required to explore the remaining causes for the scatter and the tl age trend however it is clear from the present study that induced tl has the potential for dating volcanism on the 2200 to 400 000 year time frame this dating method if successful would be well suited to spacecraft use since it requires low mass and low power instruments with a low data demand

chemical and physical studies of type 3 chondrites i metamorphism related studies of antarctic and other type 3 ordinary chondrites abstract thermoluminescence sensitivity measurements have been made on 18 unequilibrated ordinary chondrites 12 finds from antarctica 5 non antarctic finds and 1 fall the tl sensitivities of these meteorites normalized to dhajala range from 0 034 st mary s county to 2 3 allan hills a78084 and based primarily on these data petrologic type assignments range from 3 3 st mary s county to 3 9 allan hills a78084 although the very low levels of metamorphism experienced by types 3 0 to 3 4 evidently cause large changes in tl sensitivity the new data demonstrate that they are unable to cause any appreciable homogenization of silicate compositions we have therefore slightly revised the silicate heterogeneity ranges corresponding to the lower petrologic types we have discovered that the temperature of maximum tl emission and the broadness of the major tl peak vary systematically with tl sensitivity as tl increases these parameters first decrease and then increase several mechanisms which could account partially or completely for the relationship between tl sensitivity and metamorphism are discussed those which involve the formation of feldspar the tl phosphor in equilibrated meteorites seem to be consistent with the trends in peak temperature and peak width since experiments on terrestrial albite show that the tl peak broadens and moves to higher temperatures as the stable form changes from the low ordered state to the high disordered state the post metamorphism equilibration temperature of type 3 5 meteorites would then correspond to the transformation temperature for the high to low form of meteorite feldspar other factors which may be involved are obscuration of the tl by carbonaceous material changes in the composition of the phosphor and changes in the identity of the phosphor

sea level rise from glaciers and ice caps a lower bound 1 one of the most easily measured dimensions of a glacier the accumulation area is linked to future changes in glacier volume and consequent changes in sea level currently observed accumulation areas are too small forcing glaciers to lose 27 of their volume to attain equilibrium with current climate as a result at least 184 33 mm of sea level rise are necessitated by mass wastage of the world s mountain glaciers and ice caps even if the climate does not continue to warm if the climate continues to warm along current trends a minimum of 373 21 mm of sea level rise over the next 100 years is expected from glaciers and ice caps when compared to recent estimates from all other sources melt water from glaciers must be considered as a particularly important fraction of the total sea level rise expected this century

basal shear stress of the ross ice streams from control method inversions 1 we used control method inversions to determine the basal shear stress beneath the ross ice streams where new high resolution velocity data sets have recently become available the inversion algorithm was adapted from an earlier viscous bed algorithm to allow solution for the basal shear stress corresponding to a weak plastic bed we performed several experiments using synthetic data to determine the quality of the inversions these experiments indicate that with high quality surface elevation data e g errors 5 m the inversions are relatively robust with respect to errors in ice flow velocity and bed topography the inversions are consistent with seismic and borehole observations and indicate that the ross ice streams lie atop a bed that is nearly everywhere weak in contrast the tributaries feeding these ice streams overlie alternating patches of strong and weak bed

regional and global volumes of glaciers derived from statistical upscaling of glacier inventory data 1 very few global scale ice volume estimates are available for mountain glaciers and ice caps although such estimates are crucial for any attempts to project their contribution to sea level rise in the future we present a statistical method for deriving regional and global ice volumes from regional glacier area distributions and volume area scaling using glacier area data from 123 000 glaciers from a recently extended world glacier inventory we compute glacier volumes and their sea level equivalent sle for 19 glacierized regions containing all mountain glaciers and ice caps on earth on the basis of total glacierized area of 741 103 68 103 km2 we estimate a total ice volume of 241 103 29 103 km3 corresponding to 0 60 0 07 m sle of which 32 is due to glaciers in greenland and antarctica apart from the ice sheets however our estimate is sensitive to assumptions on volume area scaling coefficients and glacier area distributions in the regions that are poorly inventoried i e antarctica north america greenland and patagonia this emphasizes the need for more volume observations especially of large glaciers and a more complete world glacier inventory in order to reduce uncertainties and to arrive at firmer volume estimates for all mountain glaciers and ice caps

estimate of the total volume of svalbard glaciers and their potential contribution to sea level rise using new regionally based scaling relationships we present a set of new volume scaling relationships specific to svalbard glaciers derived from a sample of 60 volume area pairs glacier volumes are computed from ground penetrating radar gpr retrieved ice thickness measurements which have been compiled from different sources for this study the most precise scaling models in terms of lowest cross validation errors are obtained using a multivariate approach where in addition to glacier area glacier length and elevation range are also used as predictors using this multivariate scaling approach together with the randolph glacier inventory v3 2 for svalbard and jan mayen we obtain a regional volume estimate of 6700 835 km3 or 17 2 mm of sea level equivalent sle this result lies in the mid to low range of recently published estimates which show values as varied as 13 and 24 mm sle we assess the sensitivity of the scaling exponents to glacier characteristics such as size aspect ratio and average slope and find that the volume of steep slope and cirque type glaciers is not very sensitive to changes in glacier area

constraints on the thermal and mixing history of lunar surface materials and comparisons with basaltic meteorites we have measured the induced thermoluminescence tl properties of mare basalts highland rocks glasses regolith breccias soils and core samples we also performed a series of heating experiments and made cathodoluminescence cl observations of apollo 16 soils the data are readily interpreted in terms of feldspar being the dominant source of tl and cl the known luminescence properties of feldspar and history of the samples for example the tl sensitivity of the mare basalts is lower than that of the highland basalts by about an order of magnitude probably due to the differing feo content of their feldspars similarly the tl properties of regolith breccias can readily be explained in terms of thermal processes similar to those experienced by the soils and by mixing of highland and mare components our major new observations and interpretations include 1 that there are maturity dependent variations in the tl and cl properties of the core samples which reflect thermal annealing and melting during regolith working 2 that the most primitive material in lunar samples in terms of their thermal histories is located in the immature lunar soils and 3 that there is no tl evidence for widespread long term thermal metamorphism of lunar samples tl being particularly sensitive to low level metamorphism in extraterrestrial materials in this latter respect lunar samples differ from basaltic meteorites which otherwise have very similar properties and histories we argue that this reflects a greater tendency toward thick regoliths on asteroid sized bodies

studies of an artificially shock loaded h group chondrite five samples of the naturally unshocked kernouve h6 meteorite were artificially shock loaded to pressures of 70 165 270 and 390 kbar and the silicates and metal examined optically by scanning and transmission electron microscopy and by thermoluminescence tl olivine deformation is closely comparable to that in naturally shocked meteorites producing dislocations with burgers vector 001 at pressures of 165 kbar these are formed in well defined slip planes at 270 kbar olivine develops optical mosaicism has high dislocation densities throughout and is also highly fractured recovery due to heating is minimal in orthopyroxene the deformation mechanism changes from the clino inversion to unit dislocation slip between 70 and 165 kbar in diopside 001 and 100 twinning was produced plagioclase is inferred to have been progressively converted to maskelynite but some is still present in 270 kbar sample the microhardness of the kamacite in the samples increases with shock pressure the transformation pressure in the kamacite is 30 40 kbar higher than observed for iron meteorites annealed kamacite displays incipient polycrystallinity and martensite and taenite sometimes contains slip lines troilite acquired cracks undulose extinction twins polycrystallinity and finally melted as the shock pressure increased at pressures over 200 kbar there was a systematic decrease in the natural tl and the tl sensitivity detailed considerations of changes in the natural tltl sensitivity ratio for various regions of the tl glow curve suggest that two processes were effective during shock thermal drainage of electron traps and a reduction in the effective trap density it is suggested that the latter process associated with the vitrification of feldspar the tl phosphor an additional sample was subjected to a shock pulse which was spiked instead of square very distinctive changes were apparent thermal effects are conspicuous and with widespread annealing 600 800 c of metal and sulfide glassy opaque veins were produced which are analogous to the black veins in shock lithified gas rich meteorites anomalous low temperature tl was induced suggesting that a new or modified phase or mineral has become the dominant tl phosphor

soil erosion risk scenarios in the mediterranean environment using rusle and gis an application model for calabria southern italy abstract soil erosion by water wse has become a relevant issue at the mediterranean level in particular natural conditions and human impact have made the calabria southern italy particularly prone to intense wse the purpose of this investigation is to identify areas highly affected by wse in calabria by comparing the scenarios obtained by assuming control and preventive measures and actions as well as actual conditions generated by forest fires also in the presence of conditions of maximum rainfall erosion geographic information system techniques have been adopted to treat data of reasonable spatial resolution obtained at a regional scale for application to the rusle model this work is based on the comparison of such data with a basic scenario that has been defined by the present situation present scenario in this scenario i r has been assessed by means of an experimental relation adjusted to calabria on the basis of 5 min observations ii k has been drawn from the soil map of calabria including 160 soilscapes iii ls has been estimated according to the rusle2 model by using among other subfactors a 40 m square cell dtm iv c has been derived by processing the data inferred from the project corine land cover whose legend includes 35 different land uses on three levels and v p has been hypothesized as equal to 1 for the remaining three hypothesized scenarios the rusle factors have been adjusted according to experimental data and to data in the literature in particular forest areas subject to fire have been randomly generated as far as fire location extension structure and intensity are concerned the values obtained by the application of the rusle model have emphasized that land management by means of measures and actions for reducing wse causes a notable reduction of the erosive rate decreasing from 30 to 12 3 mg ha 1 y 1 on the other hand variations induced by hypothetical wildfires in forests on 10 of the regional territory bring wse over the whole region to values varying from 30 to 116 mg ha 1 y 1 this study can be offered to territorial planning authorities as an evaluation instrument as it highlights the merits and limitations of some territorial management actions in fact in calabria no observations exist concerning the implications of these actions

micromechanical modelling of rainsplash erosion in unsaturated soils by discrete element method abstract the rainsplash erosion is one important mechanism in natural and artificial slopes and the raindrops impact contributes to the amount of solids conveyed at the outlet of a mountain basin rainsplash erosion involves individual or small clusters of soil particles it is a dynamic temporally and spatially variable process and mainly occurs in unsaturated soils where capillarity forces allow steep slopes to be stable the discrete element method dem was firstly applied in this paper for the analysis of rainsplash erosion assuming realistic rainfall intensities and a range of both slope steepness and capillary forces in a parametric analysis the dem numerical results highlight the specific role of the slope steepness capillarity force and rainfall intensity towards the final volume of the solid eroded from the ground surface at the computational domain it is also valuable that the numerical results are in good agreement with literature formulations and increasing power law functions were found to relate well the eroded volume to rainfall intensity

theory of lattice boltzmann simulations of glacier flow a lattice boltzmann technique for modeling navier stokes fluid flow is extended to allow steady state simulations of glaciers and other slow flowing solids the technique is based on a statistical mechanical representation of flowing ice as a set of particles populations which translate and collide on a face centered cubic lattice the average trajectories of the populations give the velocities of the ice at any point in the glacier the method has considerable advantages over other techniques including its ability to handle complex realistic geometries without additional complications to the code examples are presented for two dimensional simulations

shesed a physically based distributed erosion and sediment yield component for the she hydrological modelling system abstract shesed is introduced as a physically based spatially distributed erosion and sediment yield component for the existing she hydrological modelling system for use at the catchment scale for hillslopes represented spatially by the she grid square network shesed simulates soil erosion by raindrop impact leaf drip and sheet overland flow without rilling and the transport of the eroded material by overland flow for channels the component simulates the erosion of bed material and the downstream transport of this material together with that supplied by overland flow in the channel sediment routing procedure it is assumed that the flow can carry any available load of fine sediments less than 0 062 mm in diameter but for coarser sediments the load is limited by the calculated capacity transport rate of the flow the channel component also allows for bed armouring application of shesed to rainfall induced sediment yield events at two agricultural catchments areas 5 1 and 6 4 ha in iowa shows generally good reproduction of the observed temporal variations in sediment yield application to a 3 3 km reach of the east fork river wyoming for a 37 day period shows good reproduction of observed sediment discharge magnitudes but some discrepancy in the timing of the simulated sediment discharge peak

the physical basis of glacier volume area scaling ice volumes are known for only a few of the roughly 160 000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates a scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas the relationship requires four closure choices for the scaling behavior of glacier widths slopes side drag and mass balance reasonable closures predict a volume area scaling exponent which is consistent with observations giving a physical and practical basis for estimating ice volumes glacier volume is insensitive to perturbations in the mass balance scaling but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume

chemical and physical studies of type 3 chondrites 2 thermoluminescence of sixteen type 3 ordinary chondrites and relationships with oxygen isotopes thermoluminescence tl sensitivity values for sixteen type 3 ordinary chondrites fourteen of them from antarctica have been measured the values obtained normalized to the tl sensitivity of the dhajala meteorite range from 1 6 allan hills a77216 to 0 010 allan hills a77176 and include two reckling peak a80207 and allan hills a77176 that are particularly low they fill a hiatus in the tl distribution that previously existed between st mary s county and bishunpur the latter being a meteorite with one of the lowest tl sensitivities known the histogram of tl sensitivity values now shows a single distribution with higher values preferred it resembles the histogram for l chondrites occupying the petrologic types 3 4 5 and 6 there is a tendency for the tl sensitivity of meteorites to decrease as 18o increases equilibrated meteorites have tl sensitivities of 5 50 and 18o 4 5 to 5 0 while the most primitive meteorites with tl 0 01 have 18o 5 7 to 6 2 meteorites with intermediate tl have intermediate 18o theoretically it is possible that the range of 18o values observed may reflect progressive loss of o in the form of co at very low temperatures but very restrictive physical conditions and a complex history seem to be required

routing graded sediments in streams formulations a one dimensional numerical model is developed for simulating the movement of well graded sediments through a stream network the model is based on the physical processes governing the mechanics of sediment movement in alluvial channels it incorporates the effect of sediment gradation on the stream s potential transport capacity it also accounts for the effect of particle exchange between the sediment load and the bed while simulating aggradation degradation and armoring of the bed the applicability of the model is restricted to noncohesive materials and relatively stable channel geometries any valid water routing algorithm can be used in simulating the movement of water

the thermoluminescence sensitivity metamorphism relationship in ordinary chondrites experimental data on the mechanism and implications for terrestrial systems hydrothermal annealing experiments have been performed on samples of the sharps meteorite in order to investigate the mechanism responsible for the metamorphism related 105 fold range in the thermoluminescence tl sensitivity in ordinary chondrites duplicate 50 mg samples of meteorite were annealed under the following conditions a 168 h at 785 c and 1 kbar b the same time temperature and pressure but with 2 wt water c 174 h at 855 c and 0 77 kbar with 2 wt water and 2 molal sodium disilicate nadisi d the same time temperature and pressure as the preceding samples but with 10 wt h2o and 2 molal nadisi samples annealed under the first three sets of conditions showed little or no change in their tl sensitivities however the samples annealed with 10 wt water and 2 molal nadisi showed a 3 to 10 fold increase in tl sensitivity and the temperature of the tl peak was suggestive of feldspar in the high temperature form we suggest that these data are consistent with the tl sensitivity metamorphism relationship in ordinary chondrites being due to the formation of the tl phosphor feldspar by the crystallization of chondrule glass

ice volume and subglacial topography for western canadian glaciers from mass balance fields thinning rates and a bed stress model abstracta method is described to estimate the thickness of glacier ice using information derived from the measured ice extent surface topography surface mass balance and rate of thinning or thickening of the ice column shear stress beneath an ice column is assumed to be simply related to ice thickness and surface slope as for an inclined slab but this calculation is cast as a linear optimization problem so that a smoothness regularization can be applied assignment of bed stress is based on the flow law for ice and a mass balance calculation but must be preceded by delineation of the ice flow drainage basin validation of the method is accomplished by comparing thickness estimates to the known thickness generated by a numerical ice dynamics model once validated the method is used to estimate the subglacial topography for all glaciers in western canada that lie south of 60 n adding the present ice volume of each glacier gives the estimated total volume as 2320 km3 equivalent to 5 8 mm of sea leve

fall recovery and characterization of the novato l6 chondrite breccia the novato l6 chondrite fragmental breccia fell in california on 17 october 2012 and was recovered after the cameras for allsky meteor surveillance cams project determined the meteor s trajectory between 95 and 46 km altitude the final fragmentation from 42 to 22 km altitude was exceptionally well documented by digital photographs the first sample was recovered before rain hit the area first results from a consortium study of the meteorite s characterization cosmogenic and radiogenic nuclides origin and conditions of the fall are presented some meteorites did not retain fusion crust and show evidence of spallation before entry the meteoroid was 35 5 cm in diameter mass 80 35 kg with a cosmic ray exposure age of 9 1 ma if it had a one stage exposure history a two stage exposure history is more likely with lower shielding in the last few ma thermoluminescence data suggest a collision event within the last similar to 0 1 ma novato probably belonged to the class of shocked l chondrites that have a common shock age of 470 ma based on the u th he age of 420 220 ma the measured orbits of novato jesenice and innisfree are consistent with a proposed origin of these shocked l chondrites in the gefion asteroid family perhaps directly via the 5 2 mean motion resonance with jupiter novato experienced a stronger compaction than did other l6 chondrites of shock stage s4 despite this a freshly broken surface shows a wide range of organic compounds less

accumulation mechanisms and the weathering of antarctic equilibrated ordinary chondrites induced thermoluminescence tl is used to quantitatively evaluate the degree of weathering of meteorites found in antarctica we find a weak correlation between tl sensitivity and descriptions of weathering in hand specimens the highly weathered meteorites having lower tl sensitivity than unweathered meteorites analysis of samples taken throughout large meteorites shows that the heterogeneity in tl sensitivity within meteorite finds is not large relative to the range exhibited by different weathered meteorites the tl sensitivity values can be restored by minimal acid washing suggesting the lower tl sensitivities of weathered meteorites reflects thin weathering rims on mineral grains or coating of these grains by iron oxides produced by hydration and oxidation of metal and sulfides small meteorites may tend to be more highly weathered than large meteorites at the allan hills ice fields we find that meteorite fragments 150 g may take up to 300 000 years to reach the highest degrees of weathering while meteorites 150 g require 40 000 years however at other fields local environmental conditions and variability in terrestrial history are more important in determining weathering than size alone weathering correlates poorly with surface exposure duration presumably because weathering occurs primarily during interglacial periods the allan hills locality has served as a fairly stable surface over the last 100 000 years or so and has efficiently preserved both small and large meteorites meteorites from lewis cliff however have experienced extensive weathering probably because of increased surface melt water from nearby outcrops meteorites from the elephant moraine locality tend to exhibit only minor degrees of weathering but small meteorites are less weathered than large meteorites which we suggest is due to the loss of small meteorites by aeolian transport

stress gradient coupling in glacier flow iii exact longitudinal equilibrium equation the vertically integrated exact longitudinal stress equilibrium equation of budd 1970 is developed further in such a way as to yield an equation that gives explicitly and exactly the contributions to the basal shear stress made by surface and bed slope surface curvature longitudinal stress deviators and longitudinal stress gradients in a glacier flowing in plane strain over a bed of longitudinally varying slope with this exact equation questions raised by various approximate forms of the longitudinal equilibrium equation can be answered decisively and the magnitude of errors in the approximations can be estimated to first order in the angle that describes fluctuations in the surface slope from its mean value the exact equilibrium equation reduces to 1 2sin 2 b pghsin 2g t b k where g and t are the well known stress deviator gradient and variational stress terms k is a longitudinal curvature term and b is a basal drag term that contributes a resistance to sliding across basal hills and valleys except for t these terms are expressed in simple form and evaluated for practical situations the bed slope relative to the mean slope is not assumed to be small which allows the effects of bedrock topography to be determined particularly through their appearance in the b term

chemical and physical studies of type 3 chondrites iv annealing studies of a type 3 4 ordinary chondrite and the metamorphic history of meteorites abstract samples of a type 3 4 chondrite have been annealed at 400 1000 c for 1 200 hours their thermoluminescence properties determined and analyzed for k na mn sc and ca by instrumental neutron activation analysis after annealing at 900 c the samples showed a 50 decrease in tl sensitivity while after annealing at 1000 c it fell to 0 1 0 01 times its unannealed value and loss of na and k occurred the tl and compositional changes resemble those observed for the equilibrated kernouve chondrite after similar annealing treatments except that the sharp tl decrease and element loss occurred at 1100 c this difference is presumably due to petrographic differences in the feldspar of the two meteorites the temperature and the width of the tl peak showed a discontinuous increase after annealing at 800 c peak temperature jumped from 130 to 200 c and peak width increased from 90 to 150 c the activation energies for these tl changes are 7 10 kcal mole similar increases in the tl peak temperature have been reported in tl studies of amelia va albite where they were associated with the low to high temperature transformation however the activation energy for the transformation is 80 kcal mole these changes in tl emission characteristics resemble trends observed in type 3 ordinary chondrites and it is suggested that type 3 3 3 5 chondrites have a low feldspar as tl phosphor and 3 5 have high feldspar as the phosphor thermoluminescence therefore provides a means of palaeothermometry for type 3 ordinary chondrites

simulation of bed armoring in alluvial channels a numerical procedure for simulating the temporal variation of sediment transport rate and corresponding variation of bed material composition in a straight alluvial channel has been developed the procedure is based on a simple model for the exchange of grain sizes between a surface and a subsurface layer of bed sediment together with a standard bed load function verification was made with laboratory data the procedure should be a useful tool for estimates of the effect of alternative flow regulation measures on a channel bed s long term stability

distributed ice thickness and volume of all glaciers around the globe 1 a new physically based approach for calculating glacier ice thickness distribution and volume is presented and applied to all glaciers and ice caps worldwide combining glacier outlines of the globally complete randolph glacier inventory with terrain elevation models shuttle radar topography mission advanced spaceborne thermal emission and reflection radiometer we use a simple dynamic model to obtain spatially distributed thickness of individual glaciers by inverting their surface topography results are validated against a comprehensive set of thickness observations for 300 glaciers from most glacierized regions of the world for all mountain glaciers and ice caps outside of the antarctic and greenland ice sheets we find a total ice volume of 170 103 21 103 km3 or 0 43 0 06 m of potential sea level rise

a third generation erosion model the combination of probabilistic and deterministic components abstract a combination of the classical deterministic mechanics of soil erosion and stochastic description of controlling erosion factors driving and resistance forces gives significant advantages and leads to the development of a new the third generation of erosion models in contrast to existing models the stosem model allows determination of the relationship between the rate of erosion and controlling factors inside the model theoretically by a solution of the governing deterministic equations with stochastic initial and boundary conditions it is possible to calculate the mean erosion rate explicitly from the probability density functions pdfs of flow velocity soil aggregate size cohesion integrity and other basic controlling factors variability of the pdfs of controlling factors through time and space due to the changes in flow regimen and or soil composition produces differences in the structure of relationship between the mean erosion rate and controlling factors as well as in resulting mean rate of erosion the model is still far from application due to the lack of specific experimental data for validation nevertheless its theoretical basement transparency and flexibility show new direction in soil erosion science

the basal speed of valley glaciers an inverse approach geophysical inverse methods are used to calculate the basal motion of a glacier they are applied to a one dimensional forward model that can be linearized to make the analysis simpler the inverse method finds a solution that fits the data within a given error it selects for smooth solutions to discriminate against unrealistic oscillations the method is applied to a simple model glacier of uniform shape and thickness to test how well a given basal motion field can be reconstructed it shows as expected that optimizing for smoothness lowers maxima and increases minima of the solution a step change in basal velocity is drawn out in the inversion over a distance that is given by the half width of a resolving function this is typically about three times the ice thickness but is also affected by the sampling rate of the data the method is then applied to two glaciers where suitable data are available brown glacier on heard island southern indian ocean and mccall glacier in the brooks range alaska u s a the mccall results agree well with earlier estimates of basal motion

physically based modelling of shallow landslide sediment yield at a catchment scale a shallow landslide erosion and sediment yield component applicable at the basin scale has been incorporated into the physically based spatially distributed hydrological and sediment transport modelling system shetran the component determines when and where landslides occur in a basin in response to time varying rainfall and snowmelt the volume of material eroded and released for onward transport and the impact on basin sediment yield derived relationships are used to link the shetran grid resolution up to 1 km at which the basin hydrology and final sediment yield is modelled to a subgrid resolution typically around 10 100 m at which landslide occurrence and erosion is modelled the subgrid discretization landslide susceptibility and potential landslide impact are determined in advance using a geographic information system gis with shetran then providing information on temporal variation in the factors controlling landsliding the ability to simulate landslide sediment yield is demonstrated by a hypothetical application based on a catchment in scotland

thermoluminescence sensitivity and thermal history of type 3 ordinary chondrites eleven new type 3 0 3 1 chondrites and possible explanations for differences among h l and ll chondrites we review induced thermoluminescence tl data for 102 unequilibrated ordinary chondrites uocs many data just published in abstracts in order to identify particularly primitive uocs and further explore tl systematics that may have implications for the history of the chondrites and their parent body we have identified 11 uocs of petrologic types 3 0 3 1 adrar 003 elephant moraine eet 90066 eet 90161 grosvenor mountains gro 95502 lewis cliff lew 88477 meteorite hills met 96503 yamato y 790787 y 791324 y 791558 y 793565 and y 793596 these samples represent an important new resource for researchers interested in the nature of primitive solar system materials previously reported trends in which tl sensitivity increases with tl peak temperature and tl peak width which we interpret in terms of crystallization of feldspar in the ordered or disordered forms during metamorphism are confirmed by the new data importantly the present data strengthen the trend described earlier in which the mean level of metamorphism experienced by uocs increases along the series ll l and h this suggests either different burial depths for the uocs from each class or formation at similar depths in regoliths of different thickness

glacier volume estimation as an ill posed inversion estimating a glacier s volume by inferring properties at depth e g bed topography or basal slip from properties observed at the surface e g area and slope creates a calculation instability that grows exponentially with the size of the glacier random errors from this inversion instability can overwhelm all other sources of error and can corrupt thickness and volume calculations unless problematic short spatial wavelengths are specifically excluded volume area scaling inherently filters these short wavelengths and automatically eliminates the instability while numerical inversions can also give stable solutions by filtering the correct wavelengths explicitly as is frequently done when regularizing a model each of the scaling and numerical techniques has applications to which it is better suited and there are trade offs in resolution and accuracy but when calculating volume neither the modeling nor the scaling approach offers a fundamental advantage over the other both are significantly limited by the inherently ill posed inversion and even though both provide stable volume solutions neither can give unique solutions

thermoluminescence and the shock and reheating history of meteorites iv the induced tl properties of type 4 6 ordinary chondrites abstract the induced thermoluminescence tl properties of 121 equilibrated ordinary chondrites have been measured the samples were 74 h and 47 l chondrites of which 33 h and 32 l were from antarctica the distribution of tl sensitivities for non antarctic l chondrites differs from that of non antarctic h chondrites consistent with a greater proportion of the former class suffering post metamorphic shock data on the effect of laboratory annealing on tl sensitivity and step wise ar release measurements enable the meteorites to be sorted into three shock related temperature groups

thermoluminescence and the shock and reheating history of meteorites iii the shergottites abstract the thermoluminescence tl sensitivities of the four shergottites are extremely low and display a 10 fold range values are 0 15 to 1 8 where dhajala 1000 with the tl sensitivity decreasing with increasing peak temperature from about 140 to 180 c and peak width from about 100 to 150 c a mineral separation experiment indicates that the mineral producing the tl is associated with the maskelynite presumably nanogram per gram quantities of crystalline feldspar are present in the maskelynite samples of shergotty allan hills a77005 and elephant moraine a79001 were annealed at 400 900 c for 24 98 h for shergotty the peak increased in width and moved to higher temperatures in the glow curve while for allan hills a77005 and elephant moraine a79001 whose tl peaks were already broad and at high temperatures remained unchanged all samples showed a significant increase in tl sensitivity when annealed at 600 700 c apparently the feldspar is present in varying proportions of high to low temperature form and in amounts which vary from meteorite to meteorite we conclude that the shergottites underwent post shock recrystallization at a variety of cooling rates and that the order of increasing cooling rate was shergotty allan hills a77005 zagami and elephant moraine a79001 the presence of a high temperature phase implies peak post shock cooling temperatures 600 c and that the size of the ejecta was

thermoluminescence and the shock and reheating history of meteorites ii annealing studies of the kernouve meteorite abstract samples of the unshocked equilibrated chondrite kernouve h6 have been annealed for 1 100 hours at 500 1200 c their thermoluminescence sensitivity measured and na k mn ca and sc determined by instrumental neutron activation analysis the tl sensitivity decreased with temperature until by 1000 c it had fallen by 40 the process responsible has an activation energy of 8 kcal mole and probably involves diffusion samples annealed 1000 1200 c had tl sensitivities 10 2 times the unannealed values most of the decrease occurring 1100 c this process has an activation energy of 100 kcal mole and is probably related to the melting of the tl phosphor feldspar with some decomposition and loss of cs na and k meteorites whose petrography indicates healing 1100 c by natural shock heating events shock facies d f have tl sensitivities similar to samples annealed 1100 c our own and literature compositional data indicate that tl is more stable to annealing than ag in tl bi zn and te and less stable than na k mn ca se and co while the tl decrease resembles very closely the pattern of cs loss on annealing

an iterative scheme for determining glacier velocities and stresses there are no direct methods to measure the boundary condition at the base of a glacier here we propose a method that works by iteratively changing boundary conditions until a satisfactory fit to surface observations is obtained the method is an accelerated version of one known as kozlov maz ya iteration we apply it to the problem of ice flow through a transverse cross section and show it to be effective by solving the inverse problem for a sequence of synthetic data we also apply the method to two real glaciers athabasca and perito moreno one of which has a known basal velocity distribution

thermal annealing of experimentally shocked feldspar crystals single crystals of sanidine orthoclase microcline oligoclase and labradorite as well as polycrystalline bytownite were shocked experimentally to peak pressures as high as 45 gpa and subsequently annealed under dry conditions for various times at 800 c 900 c and 1000 c these experiments reveal that alkali feldspars do not change their al si distribution due to shock alone but when subjected to shock pressures 22 gpa and then annealed microcline and orthoclase rapidly transform to sanidine displaying a highly disordered al si distribution high diffusivity of k na and ca was observed in a labradorite sample shocked to 26 gpa subsequent annealing may thus disturb chemical structural and isotopic characteristics of shocked minerals and rocks more easily than of unshocked specimens this is of considerable importance for the interpretation of isotopic age data of impact breccias recrystallization textures of annealed diaplectic plagioclase glasses are very distinctive and may be used as a relative measure of the shock pressure experienced by the samples

tribs erosion a parsimonious physically based model for studying catchment hydro geomorphic response our goal is to develop a model capable to discern the response of a watershed to different erosion mechanisms we propose a framework that integrates a geomorphic component into the physically based and spatially distributed tin based real time integrated basin simulator tribs model the coupled model simulates main erosive processes of hillslopes raindrop impact detachment overland flow entrainment and diffusive processes and channel erosion and deposition due to the action of water flow in addition to the spatially distributed dynamic hydrologic variables the model computes the sediment transport discharge and changes in elevation which feedback to hydrological dynamics through local changes of terrain slope aspect and drainage network configuration the model was calibrated for the lucky hills basin a semi arid watershed nested in the walnut gulch experimental watershed arizona usa it is demonstrated to be capable of reproducing main runoff and sediment yield events and accumulated volumes over the long term the model was also used to study the response of two first order synthetic basins representative of landforms dominated by fluvial and diffusive erosion processes to a 100 year long stationary climate the analysis of the resultant slope contributing area relationships for the two synthetic basins illustrates that the model is consistent with assumed principles of behavior and capable of reproducing the main mechanisms of erosion

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100

a thermoluminescence study of experimentally shock loaded oligoclase and bytownite the thermoluminescence tl of samples of terrestrial oligoclase and bytownite shock loaded to 10 5 45 gpa have been measured the tl sensitivities of both feldspars decreased 10 fold after shock loading to 25 32 gpa and for the oligoclase 25 fold after shock loading to greater pressures the shock induced changes for oligoclase are very similar to those of the kernouve meteorite in which the tl phosphor is oligoclase after similar shock loading the data indicate that ordinary chondrites of shock facies d f have suffered shock pressures over 25 gpa consistent with petrographic estimates petrographic studies on the shocked samples suggest that the lowering of tl sensitivity is caused by maskelynization and at the highest pressures melting the oligoclase samples shocked above 34 gpa showed changes in their glow curve shapes similar to those produced by annealing amelia albite and a type 3 4 ordinary chondrite above 700 c the dominant peak moves from 132 8 c to 230 12 c changes in the glow carve shape for bytownite resembled those produced by annealing certain shergottites in addition to a major peak at 138 3 c a peak appeared at 178 8 c for albite the changes were shown to be associated with small degrees of disordering and we suggest that shock induced disordering or some process closely associated with the onset of disordering is occurring in the trace amounts of feldspar that survive maskelynization after shock loading to pressures 34 gpa