argon 39 argon 37 and krypton 85 isotopes in stripa groundwaters abstract 39 ar 37 ar and 85 kr activities in groundwater samples from three boreholes in the stripa granite are compared with 222 rn activities and with data from a granitic groundwater in switzerland in situ production rates in bulk granite and in fracture filling minerals are calculated the measured isotopes in groundwater have been produced by nuclear reactions in the rock matrix it was reported earlier that a large fraction of the in situ produced 222 rn can escape to the water phase due to the unusual microscopic distribution of u which seems to be in close contact with the water phase the same conclusion can be drawn for 85 kr with escape factors between 5 and 25 the 39 ar values in stripa groundwaters are the highest measured so far but consistent with the unusually high neutron flux in stripa as compared to granites with lower u and th contents the 37 ar concentrations appear to be quite high but since it is the first time that this isotope has been identified in groundwater the basis for a comparison with different rock formations is still too small it seems possible that calcite fracture fillings in stripa have a major influence on the concentration of 37 ar in groundwater

barents sea seasonal ice zone features and processes from ers 1 synthetic aperture radar seasonal ice zone experiment 1992 sea ice features and processes in the barents sea were studied during the seasonal ice zone experiment 1992 sizex92 a dedicated ers 1 satellite synthetic aperture radar sar field campaign carried out in march 1992 sizex92 was based around the research vessels polarsyssel and hakon mosby in situ oceanographic meteorological and ice measurements were made coordinated with low altitude aerial observations and ers 1 sar data acquired in near real time fifty eight low and full resolution sar scenes were obtained during sizex92 which provided a validation data set for ers 1 sar backscatter under winter conditions in the barents sea analysis of sizex92 data has provided geophysical insights including a better understanding of barents sea ice edge freezing processes and ice edge development in response to atmospheric forcings in particular areas of new ice formation were found to be related to bathymetric features through their influence on the circulation of arctic and atlantic water masses ers 1 sar image sequences revealed rapid mesoscale variations in new ice areas and the ice edge in response to wind conditions in addition to geophysical insight sizex92 demonstrated some of the technical capabilities and limitations of ers 1 sar to identify new ice areas the ice edge ice floes and ice types mapping new ice areas using satellite sar data may be considered the most promising new application the limitations of ers 1 sar derived ice classification and ice motion estimates in the marginal ice zone are identified

analyzing lead information from sar images leads are relatively linear features in the sea ice cover which are composed of open water or new thin ice because of their composition leads impact the ocean air heat exchange automated analysis of leads from sea ice imagery may provide a means of gathering important information about the sea ice cover and its climatic influence this paper describes 1 a method for extracting and analyzing leads from ers 1 synthetic aperture radar sar images classified by ice type and 2 the results of using this method on images of the beaufort sea the methodology consists of identifying potential lead features in the image and measuring their characteristics both before and after using a thinning or skeletonization technique on the features the measurements obtained using this method include lead area average width number of leads in an area amount of branching and linearity of the lead these measurements were analyzed with respect to the time of year and the latitude of the images results indicate that the measurements produced by the methodology are consistent with lead measurement distributions that others have found the results of the study suggest that the methodology is appropriate to study lead characteristics on a large scale

hydrogeological and geochemical control of the variations of 222rn concentrations in a hard rock aquifer insights into the possible role of fracture matrix exchanges to investigate the possible variations of rn concentration in crystalline rocks as a function of flow conditions a field study was carried out of a fractured aquifer in granite the method is based on the in situ measurement of rn in groundwater aquifer tests for the determination of hydraulic characteristics of the aquifer and laboratory measurement of rn exhalation rate from rocks a simple crack model that simulates the rn concentration in waters circulating in a fracture intersecting a borehole was also tested the rn concentrations in groundwaters from boreholes of the study site ranged from 192 to 1597 bq l 1 the rn exhalation rates of selected samples of granite and micaschist were determined from laboratory experiments the results yielded fluxes varying from 0 5 to 1 3 mbq m 2 s 1 in granite and from 0 5 to 0 9 mbq m 2 s 1 in micaschists pumping tests were performed in the studied boreholes to estimate the transmissivity and calculate the equivalent hydraulic aperture of the fractures transmissivities ranged from 10 5 to 10 3 m2 s 1 using the cubic law hydraulic equivalent fracture apertures were calculated to be in the range of 0 5 2 3 mm to gain a better insight into the spatial variability of rn contents in groundwater theoretical rn concentrations were calculated from an available simple crack model using results from field and laboratory experiments this model gave satisfactory results for boreholes characterized by low flow conditions in which case the calculated rn contents were in the range of rn concentrations set by the analytical uncertainty of concentrations measured in water however for boreholes characterized by high flow conditions the model underestimated the rn concentration in groundwater the higher the flow in the fracture the larger the difference between calculated and measured rn concentrations in water these observations led to performing pumping tests to obtain a better understanding of the hydrogeological control of rn content in water the results clearly show an increase of rn content in groundwater after the pumping test which could be explained by the input of rn rich waters from the host matrix

transport of radon in flowing boreholes at stripa sweden granitic rock in an underground experimental waste storage site at stripa sweden is unusually high in natural radioelements 40 ppm uranium with higher concentrations occurring locally in thin chloritic zones and fractures consequently groundwater seeping through fractures into open boreholes is highly anomalous in its radon content with activity as high as 1 ci 1 when total count gamma ray logs are run in boreholes where groundwater inflow is appreciable the result is quite unusual the radon daughter activity in the water adds considerably to the gamma contribution from the rock and in fact often dominates the log the total gamma activity increases where radon charged groundwater enters a borehole and decays as the water flows along the hole in response to the hydraulic gradient as a consequence the gamma log serves as a flow profile locating zones of water entry or loss by an increase or decrease in the total gamma activity if mixing within the borehole does not occur the activity decreases exponentially along the hole away from the entry point because of the steady decay of radon and its daughter products as they migrate with the flow in the water column this spatial decay rate can be converted to a linear flow rate since the 3 8 day half life of radon governs the response time for example if the volumetric flow rate in a 76 mm hole falls within the range 0 5 50 liters per day and if observations are available from a 10 m length of hole then the flow rate can be measured quantitatively proportionately higher rates can be measured if longer hole lengths are available for observation a model for flow through a thin crack emanating radon at a rate e shows that the radon concentration of water entering a hole is e h where is the radon decay rate and h the crack aperture assuming that the flow rate and crack source area are such that an element of water resides within the source area for several radon half lives or more using this simple relationship independent measurements of emanation and concentration produce reasonable estimates of fracture aperture although uranium concentration values at stripa are unusually high neither the emanation coefficients nor the fracture properties appear to be unusual for granitic rock it therefore seems likely that many granitic sites must exist where the radon content in groundwater is higher than in other geological terranes although perhaps not as high as the microcurie per liter concentrations found at the stripa site

multifrequency polarimetric synthetic aperture radar observations of sea ice the first known fully polarimetric airborne synthetic aperture radar sar data set of sea ice is introduced images were acquired in the beaufort bering and chukchi seas in march 1988 during a campaign for validation of defense meteorological satellite program special sensor microwave imager radiometer ice products statistics of the magnitude phase and polarization of complex backscattered signals recorded by the jet propulsion laboratory three frequency sar are examined in detail for various scenes with different ice characteristics the full stokes matrix information generated from c l and p band data characterize the scattering behavior of different ice types polarization ratios and phase differences between linear copolarized returns are used for discrimination between particular image features and mechanisms are suggested for the observed polarimetric characteristics results indicate that combinations of frequency and polarization enhance current capability to distinguish ice of different properties using single frequency fixed polarization micro wave radar a specific example is the polarimetric identification of new ice formation which may not be easily distinguished in ers 1 5 3ghz vv polarization sar data such findings are consistent with theoretical model simulations of scattering characteristics of sea ice overall these preliminary results demonstrate that radar polarimetry will likely add a new dimension to our current capability for extracting geophysically important ice variables using radar remote sensing methods

a random discontinuous model of sea ice motion the rate at which the sea ice pack spreads apart exposing the warm ocean to the cold atmosphere controls the air sea heat exchange in the arctic and the production of ice mass the rate of spreading or opening can be estimated from observations of ice motion using a model of the ice pack which accounts for the random manner in which the ice is broken into rigid pieces in a region intersected by many cracks some cracks will typically be opening while others are closing in this case the total of the openings will exceed the average divergence of the region a few measurements of the ice motion cannot resolve the openings at each crack so that any estimate of opening will be accompanied by estimation errors the random model adopted here imagines the leads to be distributed according to the poisson distribution and the relative displacements at any crack to be gaussian under these assumptions it is determined how the total opening is related to the average deformation and how this relationship depends on the size of the region and on the number of points used to determine the average deformation

contrasts in sea ice deformation and production in the arctic seasonal and perennial ice zones 1 four years 1997 2000 of radarsat geophysical processor system rgps data are used to contrast the sea ice deformation and production regionally and in the seasonal siz and perennial piz ice zones ice production is of seasonal ice in openings during the winter three day estimates of these quantities are provided within lagrangian elements initially 10 km on a side a distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the midwinter regional divergence over the winter could be up to 30 spatially the highest deformation is seen in the siz north of coastal alaska both ice deformation and production are higher in the siz deformation related ice production in the siz 0 5 m is 1 5 2 3 times that of the piz 0 3 m this is connected to ice strength and thickness atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability seasonal ice growth in ice fractures accounts for 25 40 of the total ice production of the arctic ocean uncertainties in these estimates are discussed by itself this deformation ice production relationship could be considered a negative feedback when thickness is perturbed however the overall effect on ice production in the face of increasing seasonal and thinner weaker ice coverage could be modified by local destabilization of the water column promoting overturning of warmer water due to increased brine rejection and the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice divergence is shown to be negligibly correlated to cyclonic motion in summer and winter in both ice zones

pan arctic lead detection from modis thermal infrared imagery polynyas and leads are key elements of the wintertime arctic sea ice cover they play a crucial role in surface heat loss potential ice formation and consequently in the seasonal sea ice budget while polynyas are generally sufficiently large to be observed with passive microwave satellite sensors the monitoring of narrow leads requires the use of data at a higher spatial resolution we apply and evaluate different lead segmentation techniques based on sea ice surface temperatures as measured by the moderate resolution imaging spectroradiometer modis daily lead composite maps indicate the presence of cloud artifacts that arise from ambiguities in the segmentation process and shortcomings in the modis cloud mask a fuzzy cloud artifact filter is hence implemented to mitigate these effects and the associated potential misclassification of leads the filter is adjusted with reference data from thermal infrared image sequences and applied to daily modis data from january to april 2008 the daily lead product can be used to deduct the structure and dynamics of wintertime sea ice leads and to assess seasonal divergence patterns of the arctic ocean

evaluation of high resolution sea ice models on the basis of statistical and scaling properties of arctic sea ice drift and deformation sea ice drift and deformation from models are evaluated on the basis of statistical and scaling properties these properties are derived from two observation data sets the radarsat geophysical processor system rgps and buoy trajectories from the international arctic buoy program iabp two simulations obtained with the louvain la neuve ice model lim coupled to a high resolution ocean model and a simulation obtained with the los alamos sea ice model cice were analyzed model ice drift compares well with observations in terms of large scale velocity field and distributions of velocity fluctuations although a significant bias on the mean ice speed is noted on the other hand the statistical properties of ice deformation are not well simulated by the models 1 the distributions of strain rates are incorrect rgps distributions of strain rates are power law tailed i e exhibit wild randomness whereas models distributions remain in the gaussian attraction basin i e exhibit mild randomness 2 the models are unable to reproduce the spatial and temporal correlations of the deformation fields in the observations ice deformation follows spatial and temporal scaling laws that express the heterogeneity and the intermittency of deformation these relations do not appear in simulated ice deformation mean deformation in models is almost scale independent the statistical properties of ice deformation are a signature of the ice mechanical behavior the present work therefore suggests that the mechanical framework currently used by models is inappropriate a different modeling framework based on elastic interactions could improve the representation of the statistical and scaling properties of ice deformation

the implications of laboratory222rn flux measurements to the radioactivity in groundwaters the case of a karstic limestone aquifer laboratory time scale experiments were conducted on carboniferous limestone gravels from the mendip hills area england with the purpose of evaluating the release of 222 rn to the water phase the specific surface areas of the samples were 4 14 and 1 69 cm 2 g 1 which provided respectively values of 50 6 and 12 7 pci for the released rn these results allowed the calculation of the emanation coefficient of this rock matrix with respect to the release of rn where completely different values corresponding to 23 and 6 were found suggesting that the extent to which grain boundaries or imperfections in aggregates of micro crystals of calcite intersect the particle surface certainly affects the rn release they also permitted the evaluation of models for the generation of rn in rocks and transfer to water in order to interpret the radioactivity due to this gas in groundwaters from the karstic aquifer of the mendip hills area where the calculated activities in groundwater based on the values of 23 and 6 for the emanation coefficient were about 51 and 15 times higher than actually measured in groundwater therefore the emanation coefficient in nature is considerably smaller than in the lab experiment and another factor k 0 k 1 may be introduced into the equations related to the modelling with the aim of adjusting the theoretical practical results

open water production in arctic sea ice satellite measurements and model parameterizations sequential synthetic aperture radar sar images from the ers 1 spacecraft were routinely used as input to the geophysical processor system at the alaska sar facility from 1992 through 1994 to produce sea ice displacement vectors on a 5 km grid we have combined some 5000 of these products consisting of nearly 700 000 displacement vectors into a set of 914 strips or mosaics of ice motion that span mostly 3 day intervals for each strip we compute the opening and closing of leads based on the change in area of the 5 km grid cells we also compute the area averaged deformation or strain invariants of the motion the small scale several kilometer lead activity can be parameterized fairly well in terms of the large scale several hundred kilometer strain invariants sea ice models implicitly contain such a parameterization through their constitutive equations the well known model of hibler 1979 that uses a viscous plastic rheology and an elliptical yield curve is in good agreement with our data the variance in the data about this theoretical relationship is less than that suggested by a random model of sea ice motion the data also indicate that shearing deformation contributes to the opening and closing of leads models with two categories or levels of ice thickness generally do not take shearing deformation into account in the evolution of the ice concentration nor do they redistribute ice as a result of ridging we show how to add these features to two level models however we argue that three level models consisting of open water thin ice and thick ice are much better suited to the proper treatment of open water production and we present such a model

impact of geohydrology and neotectonic activity on radon concentration in groundwater of intermontane doon valley outer himalaya india radon concentration was measured in 133 water samples from tubewells handpumps dug wells and springs of the doon valley outer himalaya india the observed radon values were found to vary from 10 to 154 bq l whereas radium in selected water samples varied from 0 11 to 0 75 bq l three different clusters of high radon values were observed in the north western central and south eastern parts of the doon valley these clusters were found to be associated with tectonics thrust fault and associated uranium mineralization in the area in general radon concentration in groundwater was found to be positively correlated with the depth of the wells whereas no significant correlation was observed between radon concentration in groundwater and the water temperature ph value conductivity and altitude of the water samples an attempt has also been made to determine the nature and extent of aquifers in the doon valley on radon concentration in groundwater the variation in radon concentration within the groundwater of the study area was found to be controlled by the neotectonic activity and geohydrological processes that occur in the area the impact of these activities on radon concentration in groundwater are discussed

evidence for nondiffusive transport of 86rn in the ground and a new physical model for the transport concentration of radon has been measured in the soil near the ground surface with solid state nuclear track detectors with the inverted cup technique measurements were made in the overburden at depth intervals 0 1 0 7 m at 0 1 6 m and at a constant depth of 0 2 m in a narrow rectangular matrix the results disagree with the hypothesis that radon concentration only depends upon local production and migration by diffusion with a diffusion length of about 1 m a transport length of 0 1 0 2 m is observed near the ground surface and the transport is dominated by a flow component radon measurements in the ground surface over the laisvall lead mine have given evidence of radon transport through rock exceeding a distance of 100 m which is possible only if the migration is a flow transport with a characteristic transport length larger than about 10 m day to explain the radon transport in the overburden and through the rock with a common transport system the existence of a general upward flow of geo gas is

rheology of the lithosphere selected topics we review recent results concerning the rheology of the lithosphere with special attention to the following topics 1 the flexure of the oceanic lithosphere 2 deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins 3 the rheological stratification of the continents 4 strain localization and shear zone development and 5 strain induced crystallographic preferred orientations and anisotropies in body wave velocities we conclude with a section citing the 1983 1986 rock mechanics literature by category

late quaternary environmental changes and the alluvial record in humid tropical environments abstract ice core and ocean drilling records now confirm the evidence from lakes rivers and mires concerning temperature depression in the humid tropics during the lgm by at least 5 c on land and this accords with the recent ccm1 model output there is less agreement about fluctuation in precipitation amount intensity and seasonality during the late quaternary pollen records remain indeterminate because of the absence of sites in lowland rainforest locations and a widespread hiatus in sedimentation spanning the lgm alluvial sediments have often been ignored by specialists from other disciplines but they also provide a valuable source of palaeoenvironmental information that reflects catchment wide conditions current evidence shows that prolonged sedimentation took place in stage 3 at sites in s america and se asia and this was followed by incision for up to 9 ka spanning the lgm streams either produced little sediment or were characterised by braided channels and sometimes fan deposits until the transition towards an interglacial mode took place after 12 700 bp 14 c in many places this transition was marked by large floods incision and deposition of coarse sediment but as the holocene climates stabilised and fluctuations of runoff reduced in amplitude so meandering rivers developed floodplains with thick overbank silts and clays these changes have regional and intercontinental patterns not everywhere identical in bracketing dates but demonstrating major changes to the fluvial systems as a result of profound changes to the hydrology of forested tropics during the last 60 ka

contributions of growth and deformation to monthly variability in sea ice thickness north of the coasts of greenland and the canadian arctic archipelago regional variability in monthly cryosat 2 sea ice thickness is partitioned into contributions from dynamics and thermodynamics using ice deformation calculated from large scale ice drift for five winters december to april 2011 2015 over a region of persistent convergence north of the coasts of greenland and the canadian arctic archipelago deformation explains 34 of the overall variance up to 69 in 2014 2015 in monthly thickness changes approximately 42 56 or 0 6 m of the seasonal changes in mean regional ice thickness can be attributed to divergence and shear the estimated area averaged growth of 0 12 0 03 m month compares favorably with measurements from ice mass balance buoys examination of the time variable thickness distributions shows areas covered by ice 3 m increased albeit at fairly coarse resolution this coupled analysis of thickness changes and deformation offered a first look at the character of the regional thickness redistribution process

opening and closing of sea ice leads digital measurements from synthetic aperture radar the coming opportunity to extract quantitative sea ice data from routine synthetic aperture radar imagery requires the development of automated image processing techniques an algorithm is described for measuring the opening and the closing of leads by comparing two sequential synthetic aperture radar sar digital images the pair of images is classified into leads and ice correcting for variation in brightness with range displacements are determined automatically on a regular 2 km grid on a 100 km square scene by cross correlation an algorithm groups together cells which cover a lead event the lead area change is estimated for each cell group by counting lead pixels before and after deformation all positive changes are summed to obtain the amount of opening and all negative changes give closing errors are estimated by comparison with area changes determined from manually digitized lead boundaries and are about 0 2 of the area of the scene for comparison the measured opening and closing are in the range of 1 to 3 of the scene area in ice models the openings and closings of leads are parameterized in terms of the large scale deformation sar allows us to study these parametric relations by giving us access both to direct observations of opening and closing and to detailed kinematic data from which to estimate the mean deformation in this image pair for which the deformation is nearly pure shear we find relatively small amounts of opening and closing consistent with previous observations and with parameterizations in most models the large values of opening and closing predicted by the poisson gauss kinematic model are not in evidence

extracting sea ice data from satellite sar imagery with the prospect of operational satellite sar s by the end of the decade there is a clear need to develop automated algorithms for the extraction of geophysical data about sea ice from highresolution radar imagery to this end we have developed techniques for distinguishing ice from open water and for resolving the details of deformation within areas 100 km square imaged by seasat sar the classification of ice and open water is based on the creation of a second band of image data consisting of the local variance of the original brightness the first band being a local average brightness in the space of these two variables ice and open water are separated into two distinct clusters the deformation is found on a 3 4 km mesh by local cross correlations of the brightness the strategy is to find a coarse displacement field with a highly averaged image and to proceed through a hierarchy of images with increasing resolution improving the accuracy of the displacements at each step comparison with manually determined displacement shows room for improvement in regions of high deformation by using smaller areas for cross correlation the concentration and deformation data are used together to determine localized regions of the scene where open water is produced or lost

radioelement u th rn concentrations in norwegian bedrock groundwaters twenty eight samples of groundwater from bedrock boreholes in three distinct norwegian geological provinces have been taken and analyzed for content of rn u and th together with a wide variety of minor and major species median values of 290 bq 1 7 6 g 1 and 0 02 g 1 were obtained for rn u and th respectively while maximum values were 8500 bq 1 170 g 1 and 2 2 g 1 commonly suggested drinking water limits range from 8 to 1000 bq 1 for radon and 14 to 160 g 1 for uranium radioelement content was closely related to lithology the lowest concentrations being derived from the largely caledonian rocks of the trondelag area and the highest from the precambrian iddefjord granite of southeast norway 11 boreholes where median values of 2500 bq 1 15 g 1 and 0 38 g 1 respectively were obtained the iddefjord granite is not believed to be unique in norway in yielding high dissolved radionuclide contents in groundwaters and several other granitic aquifers warrant further investigation in this respect

sea ice tracking by nested correlations spatial differences in sea ice displacement affect ice stress ice production and the mass balance of the ice cover our concepts about the spatial structure of this field have been undernourished because of a paucity of data with high spatial detail and because of the tedium of extracting such measurements from images manually a method is described that measures displacements from synthetic aperture radar digital imagery with fine spatial resolution and does so fully automatically many small areas of ice common to two images are identified by correlating the two images the strategy is to acquire a crude displacement field first from highly averaged images and to refine this field with images of successively higher resolution the median discrepancy between automatically and manually measured displacements is three pixels 0 075 km the algorithm operates successfully on compact ice with large floes and modest rotation rates we believe it will prove applicable to most of the arctic ice cover throughout the year