the origin and mechanisms of salinization of the lower jordan river the chemical and isotopic 87 sr 86 sr 11 b 34 ssulfate 18 owater 15 nnitrate compositions of water from the lower jordan river and its major tributaries between the sea of galilee and the dead sea were determined in order to reveal the origin of the salinity of the jordan river we identified three separate hydrological zones along the flow of the river 1 a northern section 20 km downstream of its source where the base flow composed of diverted saline and wastewaters is modified due to discharge of shallow sulfate rich groundwater characterized by low 87 sr 86 sr 0 7072 34 ssulfate 2 high 11 b 36 15 nnitrate 15 and high 18 owater 2 to 3 values the shallow groundwater is derived from agricultural drainage water mixed with natural saline groundwater and discharges to both the jordan and yarmouk rivers the contribution of the groundwater component in the jordan river flow deduced from mixing relationships of solutes and strontium isotopes varies from 20 to 50 of the total flow 2 a central zone 20 50 km downstream from its source where salt variations are minimal and the rise of 87 sr 86 sr and so4 cl ratios reflects predominance of eastern surface water flows 3 a southern section 50 100 km downstream of its source where the total dissolved solids of the jordan river increase particularly during the spring 70 80 km and summer 80 100 km to values as high as 11 1 g l variations in the chemical and isotopic compositions of river water along the southern section suggest that the zarqa river 87 sr 86 sr0 70865 11 b25 has a negligible affect on the jordan river instead the river quality is influenced primarily by groundwater discharge composed of sulfate rich saline groundwater cl 31 180 mm so4 cl0 2 0 5 br cl2 310 3 87 sr 86 sr0 70805 11 b30 15 nnitrate 17 34 ssulfate4 10 and ca chloride rift valley brines cl 846 1500 mm br cl 6 8 10 3 87 sr 86 sr0 7080 11 b40 34 ssulfate4 10 mixing calculations indicate that the groundwater discharged to the river is composed of varying proportions of brines and sulfate rich saline groundwater solute mass balance calculations point to a 10 contribution of saline groundwater cl282 to 564 mm to the river a high nitrate level up to 2 5 mm in the groundwater suggests that drainage of wastewater derived irrigation water is an important source for the groundwater this irrigation water appears to leach pleistocene sediments of the jordan valley resulting in elevated sulfate contents and altered strontium and boron isotopic compo sitions of the groundwater that in turn impacts the water quality of the lower jordan river copyright 2004 elsevier ltd

deuterium in north atlantic storm tops abstract during the erica project in 1989 ice crystals were collected from the tops bf two winter storms and one broad cirrus cloud deuterium concentration in the storm ice samples together with a model of isotope fractionation are used to determine the temperature where the ice was formed knowledge of the ice formation temperature allows us to determine whether the ice has fallen or been lofted to the altitude of collection in both storms the estimated fall distance decreases upward in the 21 january storm the fall distance decreases to zero at the cloud top in the 23 january storm the fall distance decreases to zero at a point 2 km below the cloud top and appears to become negative above indicating lofted ice cloud particle data from the cloud tops show an ice to vapor ratio greater than one and indicate the presence of particles with small terminal velocities both observations support the idea of ice lofting the satellite derived cloud tops lie well below the actual cloud top e g 2 5

the role of snow sublimation in frontogenesis recent work on the influence of moist processes at synoptic fronts has shown how condensation heating can be a strong and even a dominant factor in their development at mesoscale lines of convection the heating is again dominant but it is thought that cooling by the evaporation of precipitation is also a crucial factor in their development and propagation although most simple models of synoptic fronts do not attempt to simulate diabatic cooling accurately data from the fronts 87 experiment have identified evidence of a strong mesoscale downdraught below a synoptic frontal surface there has been speculation that such a downdraught is forced by the sublimation of falling snow since snow is more efficient at cooling the atmosphere for a given precipitation rate than evaporation of rain rainfall parametrizations are likely to underestimate the influence of such cooling in this paper a suitable parametrization of diabatic cooling based on the assumption of small stability to slantwise convection is used to simulate a band of snow sublimation in developing fronts the semi geostrophic equations are employed in the study of fronts which are formed by deformation or horizontal shear of the geostrophic winds it is found that the cooling has little influence on the large scales of motion and does not greatly accelerate the formation of frontal singularity however the cross frontal flows in the vicinity of the cooling are modified strongly with the formation of a narrow downdraught of comparable dimensions and intensity to that suggested by the experimental data the cooling has a weak influence on all the fields at a larger distance from the front this is discussed in the context of the large scale or geostrophic response to lines of convection

structure of a cold front over the ocean the kinematic and thermodynamic structure of a strong cold front over the gulf of alaska has been determined using aircraft dropsonde and radiosonde data obtained during the storm transfer and response experiment synoptic scale analysis using the sawyer eliassen secondary circulation equation shows that friction and diabatic heating as well as the geostrophic forcing are important in accounting for the secondary circulation at the front a fine scale analysis with horizontal resolution of 700m and vertical resolution of 100 m shows strong relative inflow of warm boundary layer air toward the front from the east and a weaker inflow of cold air from the west updraught velocities of greater than 6 m s 1 over a 2 km width were measured at 875 mb near the leading edge of the front the frontogenetical effects of confluence turbulent mixing and tilting of isentropic surfaces are evaluated in the region of the front and compared with the results of previous studies the high resolution of the thermodynamic fields provides new data for comparison with high resolution numerical models

effects of melting on frontogenesis abstract frontal precipitation systems are simulated with a 2d cloud model including ice phase microphysics despite the use of idealized frontogenetic forcing in the simulations some observed characteristics of frontal zones and their associated cloud and precipitation fields are reproduced in the simulations the effects of melting snow on surface frontogenesis is investigated it is found that the cooling effects of melting snow significantly accelerate surface frontogenesis in winter storm environments especially when the melting layer is close to the surface however the steady state surface frontal strength in the model is not sensitive to the melting effects finescale thermal and kinematic perturbations inside the frontal zone near the melting level quite similar to those recently reported in the literature are evident in the model results analysis of the model results suggests that cooling from melting snow may induce these thermal and kinematic perturbations and may enhance baroclinicity

the stable isotopes of site wide waters at an oil sands mine in northern alberta canada abstract oil sands mines have large disturbance footprints and contain a range of new landforms constructed from mine waste such as shale overburden and the byproducts of bitumen extraction such as sand and fluid fine tailings each of these landforms are a potential source of water and chemical release to adjacent surface and groundwater and consequently the development of methods to track water migration through these landforms is of importance the stable isotopes of water i e 2 h and 18 o have been widely used in hydrology and hydrogeology to characterize surface water groundwater interactions but have not been extensively applied in mining applications or specifically to oil sands mining in northern alberta a prerequisite for applying these techniques is the establishment of a local meteoric water line lmwl to characterize precipitation at the mine sites as well as the development of a catalogue of the stable water isotope signatures of various mine site waters this study was undertaken at the mildred lake mine site owned and operated by syncrude canada ltd the lmwl developed from 2 years 2009 2012 of sample collection is shown to be consistent with other lmwls in western canada the results of the study highlight the unique stable water isotope signatures associated with hydraulically placed tailings sand or fluid fine tailings and overburden shale dumps relative to natural surface water and groundwater the signature associated with the snow melt water on reclaimed landscapes was found to be similar to ground water recharge in the region the isotopic composition of the shale overburden deposits are also distinct and consistent with observations made by other researchers in western canada on undisturbed shales the process water associated with the fine and coarse tailings streams has highly enriched 2 h and 18 o signatures these signatures are developed through the non equilibrium fractionation of imported fresh river water during evaporation from cooling towers used within the raw water process circuit this highly fractionated surface water eventually becomes part of the recycled tailings water circuit and as a consequence it undergoes further non equilibrium fractionation as a result of surface evaporation leading to additional enrichment along local evaporation lines

evidence of discharging saline formation water to the athabasca river in the oil sands mining region northern alberta this paper summarizes various lines of evidence including new geophysical and geochemical surveys indicating the discharge of naturally occurring saline formation water from cretaceous and devonian formations to the athabasca river downstream of fort mcmurray an active oil sands extraction area the following features are indicative of saline water discharge i the hydrogeological setting of the reach which is situated near the western up dip and subcropping edge of the western canada sedimentary basin ii springs and seepage along area rivers and tributaries that have been observed and reported in previous studies and iii a significant increase in dissolved solids in the river particularly chloride occurring in a downstream direction from fort mcmurray further evidence of the saline groundwater discharge was obtained from electromagnetic surveys conducted along a 125 km reach from the clearwater river to the firebag river this technique was used to map the distribution of saline water in

on assessing local conditional symmetric instability from atmospheric soundings abstract the standard parcel method of assessing the susceptibility of the atmosphere to moist convection using tephigrams is extended to account for the centrifugal as well as the gravitational potential energy of the displaced air parcel this leads to a measure of the stability of the moist baroclinic atmosphere to finite slantwise reversible displacements of a two dimensional air parcel such a measure differs from previously derived measures of conditional symmetric instability which have considered only infinitesimal displacements in saturated atmospheres it is demonstrated that the combined gravitational and centrifugal potential of a two dimensional air parcel or tube can be assessed by displacing the tube slantwise along a surface of constant angular momentum and that this combined potential energy can be estimated using a single atmospheric sounding several examples of the application of this technique are presented in the context of a case study of apparent slantwise convection the result

origin and geochemistry of saline spring waters in the athabasca oil sands region alberta canada abstract the geochemistry of saline spring waters in the athabasca oil sands region aosr in alberta canada discharging from devonian carbonate rocks into the athabasca and clearwater rivers was characterized for major ions trace elements dissolved gases and polycyclic aromatic hydrocarbons pahs in addition stable isotope analyses of h2o so4 dissolved inorganic carbon dic sr and ch4 were used to trace the sources of spring waters and their dissolved solutes and to identify subsurface processes affecting water chemistry the spring waters had 18o values as low as 23 5 suggesting they are composed of up to 75 laurentide glacial meltwater tritium and radiocarbon age dating results analyzed for three spring waters supported a glacial origin the high salinity of the spring waters tds 7210 51 800 mg l was due to dissolution of devonian evaporite and carbonate deposits in the subsurface spring waters were affected by bacterial dissimilatory sulfate reduction methanogenesis and methane oxidation trace elements were present in spring waters at varying concentrations with only one spring containing several predominant oil sands metals as fe mo ni se zn suggesting bitumen as a source five springs contained elements al as b fe se at concentrations exceeding water quality guidelines for the protection of aquatic life seven pahs were detected in spring waters total pah concentrations ranged from 7 3 to 273 6 ng l but most springs contained a maximum of two pahs phenanthrene and naphthalene with more pahs being detected in springs along the athabasca river this geochemical characterization of the saline groundwater discharging from the devonian carbonates underlying oil sands deposits contributes to the knowledge of baseline groundwater chemistry in the aosr which is of importance in the delineation of natural versus anthropogenic effects on regional surface water and groundwater quality

continental erosion and large scale relief a worldwide investigation of continental erosion is carried out by the study of large drainage basins on the basis of hydrological data environmental factors and basin relief distribution inside each basin mean geochemical and mechanical denudation rates are defined a multicorrelation analysis shows that the mechanical denudation rates ds are uncorrelated with environmental factors and correlated with mean basin elevation h while chemical denudation rates dd are insensitive to relief but correlated with mean annual precipitation furthermore two linear relationships between h and ds are detected 1 ds m 10 yr 419 10 6 h m 0 245 with v explained variance 95 1 this law concerns basins related to orogenies younger than 250 ma the negative intercept is interpreted as a continental sedimentation rate of 245 m m y an alternative model in which one invokes a critical elevation separating erosion from sedimentation is equally successful and leads to lower sedimentation rates 60 110 m m y for both models one derives from the slope of the adjustments erosion time constants on the order of 2 5 m y 2 ds m 10 yr 61 10 6 h m with v 86 5 this law concerns basins related to older orogenies the null intercept suggests the lack of continental storage because of the more important dispersion of the data the erosion time constant is calculated separately for each basin it ranges from 15 to 360 m y the tectonic implications of these results are discussed in particular the short time constant 2 5 m y agrees with orogenic uplift rates on the order of 1 mm yr observed in active mountain chains

using regional datasets of isotope geochemistry to resolve complex groundwater flow and formation connectivity in northeastern alberta canada abstract in the southern athabasca oil sands saos region located in alberta canada individual in situ oil sands operators have conducted local geochemical and isotope groundwater studies to establish baseline characteristics and to improve understanding of the connectivity of water supply and disposal formations within individual leases canada s oil sands innovation alliance cosia initiated this study to combine the data from these individual studies along with public information into a comprehensive unified dataset to evaluate conceptual models of regional groundwater flow and the degree of interaction and separation between important water supply and disposal aquifers the unified dataset comprised over 293 groundwater samples from the main water source and disposal hydrostratigraphic units and included geochemical and isotopic tracers that can be used to identify sources 18o and 2h and age of water 3h and associated solutes 14cdic 36cl as well as the sources of salinity and diagenetic processes 13cdic 34sso4 87sr 86sr 11b 37cl and 81br and dissolved organics 13cdoc the tds and stable isotope composition 18o and 2h of groundwater from several cretaceous formations were used to identify three main mixing controls i areas where locally recharged groundwater mixes with glaciogenic water were identified by lower 18o and 18o values high tds cl br and 34sso4 87sr 86sr and 37cl values consistent with dissolution of evaporites these areas were situated where vertical pathways through otherwise competent formations are likely to occur ii mixing with paleo waters characterized by high tds and higher 18o and 2h signatures indicating groundwater recharged under warmer climate periods and or evaporative enrichment were identified in the south and southwestern portions of the study area the presence of these paleo waters indicate slow moving groundwater zones with limited lateral and vertical connectivity iii areas with potential connectivity to shallow aquifers were identified by their lower tds values modern meteoric 18o and 2h signatures hco3 type waters and 34s so4 and 87sr 86sr signatures consistent with weathering of shallow aquifer material geochemical and isotopic indicators suggest that in areas where the colorado group aquitard is thin or absent there is greater connectivity between the grand rapids formation and the shallower aquifers interpretation of the new unified dataset has improved understanding of the extent that glacial recharge had on devonian aquifers and overlying cretaceous formations and identified zones with relatively stagnant groundwater flow both of which have implications for regional groundwater resource development monitoring and potential wastewater disposal

estimating winter ebullition bubble volume in lake ice using ground penetrating radar freshwater lakes are an important source of atmospheric methane ch4 however uncertainties associated with quantifying fluxes limit the accuracy of climate warming projections among emission pathways ebullition bubbling is the principal and most challenging to account for given its spatial and temporal patchiness when lakes freeze many methane rich bubbles escaping from lake bottom sediments are temporarily trapped by downward growing lake ice as bubble position is then seasonally fixed we postulate that it should be possible to locate bubbles using a geophysical approach sensitive to perturbations in the ice water interface and ice sheet structure generated by bubbles this study utilizes ground penetrating radar gpr to non invasively quantify the amount of ebullition gas present in lake ice to do this requires an appropriate petrophysical transformation that relates radar wave velocity and volumetric gas content we utilized laboratory experiments to show that electromagnetic models and vo

quantifying saline groundwater seepage to surface waters in the athabasca oil sands region western canadian oil sands contain over 170 billion barrels of proven unconventional petroleum reserves currently extracted at 1 8 million barrels per day by either surface mining or by in situ techniques that require subsurface injection of steam and hydrocarbon solvents natural high salinity springs are known to add water and entrained inorganic and organic constituents to the athabasca river and its tributaries in the region of ongoing bitumen production however the magnitude and synoptic distribution of these saline inputs has remained unquantified here a chloride mass balance is used to estimate saline groundwater discharge to the athabasca river from 1987 to 2010 results show that the highest saline water discharge rate to the athabasca river occurs between ft mcmurray and the peace athabasca delta supported by subcrop exposure of lower cretaceous and devonian aged formations bearing saline waters further the input of saline groundwater is found to be an important control on the chemistry of the lower athabasca river despite comprising 10 1 to 3 of the athabasca river s discharge the flux of natural saline groundwater entering the athabasca does not appear to have increased or decreased from 1987 to 2010 the origin of seep salinity is interpreted as relict subglacial meltwater that has dissolved devonian aged evaporites supported by saline na cl type waters with low 18 o 16 o and 2 h 1 h ratios relative to modern precipitation the magnitude of groundwater discharge and its impact on the athabasca river s chemistry in the area of ongoing bitumen development warrants the incorporation of natural groundwater seepages into surface water quality monitoring networks

organic maturity in the western canada sedimentary basin abstract organic maturity of strata in the western canada sedimentary basin has been investigated in numerous studies using petrological chemical and physical methods compilation of these data has facilitated a regional analysis of the maturity patterns and maturation history variation in maturity patterns can be divided into three levels basin wide 1st order regional 2nd order and local 3rd order first order variations are manifested by an overall increase in maturity of strata of the same age from east to west from the plains to the rocky mountain foothills and front ranges in response to progressively deeper burial and higher paleo geothermal gradients superimposed on this first order basinal scale variation in maturity are second and third order variations which reflect local differences in depth of burial conductive and advective heat transport or effects of thrust faulting maturity gradients in the axis of the basin are low averaging 0 10 log r omax km whereas in the front ranges and foothills the gradients are substantially greater average 0 25 log r omax km variations in maturity gradients reflect lower paleo geothermal gradients resulting from rapid sediment loading and subsequent unloading in the plains and higher conductive heat transport in the deformed belt the main component of maturity of most phanerozoic strata occurred during deep burial under upper cretaceous and or paleogene molasse in foredeeps developed in response to crustal loading during the easterly migration of the foreland fold and thrust belt as a result of the west to east propagation of deformation during the laramide orogeny deep burial maturation hydrocarbon generation and uplift occurred earlier in the foreland belt late cretaceous than in the plains to the east where the main component of maturity and hydrocarbon generation occurred as late as eocene in the plains because of the low maturity gradients a thick succession of strata currently is within the oil window in the deformed belt however higher maturity gradients have resulted in a thinner succession of strata within the oil window in response to higher paleo geothermal gradients strata in the deformed belt matured more quickly leading to more rapid hydrocarbon generation and migration than areas to the east in the southern part of the cordillera a significant component of maturation post dates structural deformation of the strata whereas in northeastern british columbia and adjacent parts of alberta maturity primarily pre dates structural deformation data from some deep bore holes and surface samples in the southern part of the cordillera provide evidence for maturity post dating or accompanying emplacement of major overthrust sheets tectonic burial in most areas however there is no clear evidence for the timing of maturity relative to faulting or evidence of frictional heating the maturity gradients and levels of maturity of surface and near surface strata in the western plains and rocky mountain foothills indicate that a succession several kilometres of paleogene strata were deposited in these regions foredeep and subsequently eroded in response to post laramide uplift

thin ice growth the thickening of ice covers has traditionally been calculated using a method in which the thickness is assumed proportional to the square root of the accumulated freezing degree days particularly for newly formed thin ice this method overpredicts the ice thickness consideration of the thermal resistance between the top of the ice and the atmosphere results in a method which predicts linear growth with time for thin ice and transitions to the t growth at large thicknesses the method proposed here is not new but seems to be rarely used even though it requires selection of only one coefficient data from several sources including initial river ice growth sea ice growth and sludge freezing are used to validate the method and bracket the coefficient

hydrogeology of formation waters northeastern alberta basin the hydrogeological study of formation waters in the northeastern part of the alberta basin defined as the area from 55 to 58 n and from 110 to 114 w is based on information from 12 475 wells 3187 formation water analyses 2531 drill stem tests and 452 030 core plug analyses because the study area covering approximately 76 000 km2 is located at the feather edge of the basin local topography and physiographic features particularly the athabasca river system exert a strong influence on the flow of formation waters in most of the aquifers generally temperature seems to be the main controlling factor on salinity distributions the salinity of formation waters increases in the vicinity of evaporitic beds and decreases close to the surface beca se of mixing with fresh meteoric water introduced through local flow systems the lower and middle devonian pre prairie aquifer systems beneath the regionally extensive prairie aquiclude are characterized by regional topographically driven flow updip to the northeast this updip flow is opposed by buoyancy forces caused by salinity increase with temperature downdip to the southwest the post prairie devonian aquifers are characterized by transitional flow regimes because of erosion at the sub cretaceous unconformity and outcrop at the athabasca river local physiographic influences are superimposed on basin scale regional flow in these aquifers hydraulic communication between the beaverhill lake cooking lake and grosmont aquifers is inferred in places caused by cooking lake reefs penetrating the intervening shales of the lower ireton aquitard finally the retaceous aquifers all can be described as having local flow regime characteristics with no buoyancy effects as a result of recharge in topographically high areas and discharge in low regions along the valleys of the athabasca river system the flow of formation waters in northeastern alberta played an important role in the formation of the huge athabasca oil sands deposits hydrocarbons that migrated into the area from the west were trapped into local reservoirs and biodegraded and washed by fresh meteoric water introduced by local flow systems environmentally the subsurface hydrogeology in the area imposes specific constraints on waste disposal in deep formations mostly because of the absence of a thick continuous regional aquitard and because most aquifers subcrop at shallow depth or crop out and discharge along the valleys of the athabasca river system and at the basin edge

precipitation type transition regions in winter storms over southern ontario two winter storms passed through the toronto area during november and december 1987 information from radar rawinsonde and surface observations was analyzed in order to determine the kinematic flow fields and thermodynamic environment in the vicinity of the transition at the surface between snow and rain this region was also linked to heavy precipitation and thunder updrafts preferentially occurred over the snow region and deep near 0 c layers occurred in the transition region observations are consistent with a mesoscale circulation initiated by melting snow and possibly with the occurrence of symmetric instability it is further suggested that large possibly wet snowflakes being formed within such deep near 0 c layers would contribute to the radar detection of precipitation bands near the precipitation transition region

the mesoscale and microscale structure of a severe ice pellet storm abstract on 1 2 february 1992 a major storm produced a prolonged period 6 h of ice pellets over st john s newfoundland at least two key features contributed to the prolonged duration first a subsaturated region within an inversion led to a reduction in the melting rate of particles that eventually meant that they could completely refreeze in the lower subfreezing region this subsaturated region formed within descending air aloft identified by doppler radar observations second a cold core of air between the surface and the inversion was critically important for the refreezing of partially melted particles results from an airmass transformation model were used to show that the ice pellet duration was extended as a result of air traveling over sea ice as opposed to over the ocean in addition this study showed that doppler radar velocity information may be capable of estimating the base height of the above freezing temperature regime during freezing rain drizzle furthermore the doppler velocity

dating penecontemporaneous dolomitization in carbonate reservoirs paleomagnetic petrographic and geochemical constraints the predominant dolomitization in the mississippian debolt formation western canada sedimentary basin was hypothesized to be early in three gas fields based on stable oxygen and carbon isotopic values and on strontium isotope ratios that are similar to postulated mississippian dolomite values and seawater ratios respectively as the absolute age could not be determined by this method paleomagnetism was used to place constraints on the age of the dolomitization the magnetic analyses on debolt specimens from the same wells revealed three magnetization components that could be tied to geologic diagenetic events 1 a low temperature 350 degreesc and coercivity 80 mt c component of primary or early diagenetic origin that is found mostly in the fine grained limestone and dolomitic muds the preservation of a primary or early diagenetic magnetization combined with the preservation of primary isotopic values indicates that little or no extrabasinal fluid flow is likely to have occurred thus in this particular area orogenically induced fluid flow cannot explain the presence of the cretaceous b magnetization consideration of the potential methods for forming this b component suggests that it is likely an in situ chemical remanence resulting from either hydrocarbon migration or dissolution and reprecipitation of fe rich minerals in the original pore fluids

the mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones xi comparisons between observational and theoretical aspects of rainbands abstract comparisons are made between the characteristics of several types of rainbands observed in an extratropical cyclone and dynamical mechanisms relevant on the mesoscale the warm sector flow ahead of the cold front and above the cold frontal zone aloft was unstable to conditional symmetric instability and theoretical predictions for this mechanism am consistent with several aspects of the warm sector and wide cold frontal rainbands in the case of the warm sector rainbands other mechanisms e g wave cisk and mixed dynamic convective instabilities may have also played a role the core structure of the narrow cold frontal rainbands appeared to be affected by an instability that derived its energy from the horizontal shear across the surface front also many aspects of the narrow cold frontal rainband were similar to a density current shear induced gravity waves appeared to be responsible for the wavelike rainbands observed in the vicinity of the cold frontal zone aloft the orientation of the

a numerical investigation of squall lines part i the control experiment abstract a two dimensional anelastic cloud resolving numerical model was used to simulate squall systems large domain and fine grid resolutions were utilized so that both the convective and mesoscale components of squall lines could be handled adequately detailed cloud microphysics including the ice phase and the coriolis force have been included in the basic model both the life cycle and storm structure of observed squall systems have been simulated successfully some details in the observed precipitation and kinematic characteristics of squall lines such as the locations of front to rear jet core the base of the stratiform cloud the formation of a transition zone and the organized mesoscale updraft have been simulated by the model the storm generated meso scale low pressure center located behind the convective updraft has been shown to be instrumental in the initiation and maintenance of the mesoscale circulation and the associated trailing stratiform region diagnostically the horizontal

cloud layer thicknesses from a combination of surface and upper air observations abstract cloud layer thicknesses are derived from base and top altitudes by combining 14 years 1975 1988 of surface and upper air observations at 63 sites in the northern hemisphere rawinsonde observations are employed to determine the locations of cloud layer top and base by testing for dewpoint temperature depressions below some threshold value surface observations serve as quality cheeks on the rawinsonde determined cloud properties and provide cloud amount and cloud type information the dataset provides layer cloud amount cloud type high middle or low height classes cloud top heights base heights and layer thicknesses covering a range of latitudes from 0 to 80 n all data comes from land sites 34 are located in continental interiors 14 are near coasts and 15 are on islands the uncertainties in the derived cloud properties are discussed for clouds classified by low mid and high top altitudes there are strong latitudinal and seasonal variations in the layer thickness only for high

mesoscale circulations forced by melting snow part i basic simulations and dynamics abstract the melting of snow extracts latent heat of fusion from the environment the basic response of the atmosphere to this cooling by melting mechanism is investigated by using a nonlinear two dimensional numerical model it is found that the resultant melting induced circulations consist of a forced downdraft which spreads out laterally like a gravity current and transients which are gravity waves the characteristics of these mesoscale thermally driven circulations are studied under idealistic atmospheric conditions model results show that the melting associated with realistic precipitation rates up to 10 mm h 1 can induce horizontal wind perturbations of several meters per second and vertical motions of tens of centimeters per second since the gravity waves and the cold outflow current propagate away from the source they can have significant dynamic effects on the environment remote from the precipitation region moreover the melting induced near o c isothermal layer in the atmosphere alters

structure of a frontal system over the northeast pacific ocean abstract a frontal system passed over the storm transfer and response experiment project area on 17 november 1980 as revealed by ship born rawinsonde surface and radar information this northeast pacific storm exhibited three components it linked surface and 500 mb troughs with marked surface windshift and associated confluence and horizontal wind shear but exhibiting no surface temperature change a midtropospheric cold katafront and an upper moisture front that was moving ahead more rapidly than the other components the upper moisture front was marked by a moisture gradient across the trailing edge of a large cloud region that moved with the winds at 500 mb or higher due to the horizontal thermal homogeneity of the marine boundary layer the confluence associated with the surface trough did not cause low level cold frontogenesis high w values of the upper portion of the frontal system indicate that air was advected from much farther south important characteristics of frontal system evolution

ghost rock karstification of devonian limestone flooring the athabasca oil sands in western canada abstract this study interprets a new style of ghost rock karstification at a site in northeast alberta western canada the karstic area of the upper devonian paleotopography was localized at the western end of the bitumount trough a 50 km long collapse structure that resulted from removal of a 120 m thick interval of salt beds of the middle devonian prairie evaporite only 200 m below ghost rock karstification developed in massive light grey limestone beds that alternate with chlorite rich argillaceous intervals of the moberly member devonian waterways formation these weathered rock profiles expanded latterly and were deepened by slowly moving hydraulic gradient driven phreatic groundwater descending along clusters of closely spaced 2 10 cm wide joints that cross cut the fracture shattered limestone beds the uppermost beds of greyish green chlorite rich argillaceous limestone were decalcified as the flows along the joint clusters carried insoluble residues consisting of quartz silt mixed with illite chlorite clays into the substrate these chlorite rich insoluble residues accumulated as replacement fabrics within decalcified porous zones of the altered limestone in the substrate as the joint opening plugged with insoluble residues within the deepened decalcification weathered rock intervals the alterite zones expanded laterally to form vertical pod shaped structures these 5 20 m in diameter and 10 20 m deep pseudo sinkhole zones consisting of alterite retained ghost rock traces of the original limestone strata this area was subsequently covered by the lower cretaceous athabasca oil sands

mesoscale circulations initiated by melting snow a linearized model is used to examine the dynamical effects of a mesoscale temperature perturbation in the lower troposphere the perturbation is a result of nonuniform cooling of the environment by melting snow an organized mesoscale thermal circulation develops with strong vertical motions in the interior outflow at low levels and a return flow at upper levels this circulation is similar to a sea breeze circulation but is forced by an elevated horizontal temperature gradient a possible application to the problem of observed enhanced precipitation regions near a rain snow boundary is considered

rain snow boundaries over southern ontario abstract rain snow boundaries in two southern ontario storms are examined radar and satellite information were used to illustrate the nature and extent of the associated precipitation and cloud regions the deepest radar echoes and clouds occurred close to the boundary surface temperature and pressure were related to the boundary some of the changes in these parameters were shown to be attributable to melting snowflakes these radar satellite and surface observations are consistent with a mesoscale circulation driven by melting snow

the lagrangian parcel dynamics of moist symmetric instability abstract a simple model describing the slantwise ascent of a two dimensional horizontal air tube subject to moist symmetric instability is developed under the assumptions that the froude number is small and that mixing is absent it is shown that in general the horizontal velocities attained by the tube are comparable to those of the mean flow and that vertical velocities of up to a few meters per second are possible the tube ascends slantwise in such a way that its buoyancy remains nearly zero unless the environment is my very nearly moist adiabatic in which case ascent at an angle of 45 to the vertical is preferred results of the analysis support the contentions of bennetts and hoskins and emanual that moist symmetric instability is the cause of some mesoscale rainbands in a companion paper it is demonstrated that the stability of the moist baroclinic atmosphere to two dimensional slantwise displacements of arbitrary magnitude can be approximately assessed by reversibly lifting parcel along sur

the structure of a winter storm producing heavy precipitation over nova scotia abstract on 22 february 1986 nova scotia experienced heavy precipitation in the form of snow freezing precipitation and rain from a storm having a central pressure no lower than 99 3 kpa using observations obtained during the canadian atlantic storms program casp field project the mesoscale structure of this storm was investigated throughout much of the storm the lowest 1 3 km of the atmosphere over the coastline was near 0 c as a result of the diabatic process of melting and refreezing convergent flow aloft and the trajectories of particles undergoing terminal velocity changes contributed to enhanced precipitation near the coastline that was sometimes detected by radar as a precipitation band straddling the coastline a mesoscale circulation driven by melting and forced to remain linked to the coastline between the warm ocean and the cold land is consistent with the observations

ice cascade growth and decay a thermodynamic approach the ice volume evolution of a frozen waterfall or ice cascade was studied using a thermodynamic model the model was developed from meteorological data collected in the vicinity of the waterfall and validated from ice volume measurements estimated from terrestrial lidar images the ice cascade forms over a 45 m high rock wall located in northern gaspesie quebec canada two stages of formation were identified during the first stage the growth is mainly controlled by air convection around the flowing and free falling water the ice cascade growth rate increases with decreasing air temperature below 0 c and when the water flow reaches its lowest level during the second stage the ice cascade covers the entire rock wall surface water flow is isolated from the outside environment and ice volume increases asymptotically heat is evacuated from the water flow through the ice cover by conduction the growth is controlled mainly by the conductive heat loss through the ice cover but also by the longwave radiation emitted at the ice surface during the night in spring melting of the ice cascade is dependent on the air convection over the ice surface but also on the sensible heat carried by the increasing water flow and the solar radiation received during the day

basement heat flow in the western canada sedimentary basin abstract the effective thermal conductivity of the entire sedimentary succession is calculated at 487 locations in the western canada sedimentary basin based on net rock analyses and thermal conductivity values corrected for temperature and porosity effects an easterly trend of increasing values is caused by shallower burial depth and by a reduced proportion of low conductivity shales geothermal gradients calculated previously and corrected for pleistocene glaciations are used in estimating the basement heat flow after subtracting the heat generated by radioactive decay in the sedimentary strata the distribution of basement heat flow with values between 30 and 80 mw m 2 is linked with the complex structure of the basement which is comprised of archean blocks accreted terranes orogenic belts and magmatic arcs heat flow heat generation relations in alberta show that the reduced heat flow and the characteristic length scale for the uppercrust thermal layer are of the order of 35 mw m 2 and 6 km respectively

explosive cyclogenesis over the eastern united states abstract cases of explosive cyclogenesis bombs were identified over the central and eastern united states and were compared with nonexplosive cyclone development in the same region the tendency equations for vorticity and geopotential thickness and a modified divergence equation were used to find signatures of distinction between these two types of cyclogenesis whose recognition might improve forecasting skills bombs tend to show a marked decrease of vorticity with height during their incipient and explosive stages whereas regular cyclones reveal only weak vertical vorticity gradients in the troposphere the low tropospheric spin up in bombs precedes significantly that in the upper troposphere preexisting low tropospheric vorticity maxima are associated with low level jet streaks whereas regular cyclones possess an ill defined level of nondivergence i e a broad region between 800 and 400 mb of divergence values close to zero incipient bombs have a well marked zero divergence level near 50

origin and hydrogeological setting of saline groundwater discharges to the athabasca river geochemical and isotopic characterization of the hyporheic zone abstract identifying impacts of oil sands development on aquatic ecosystems requires understanding of the natural background water quality in the athabasca oil sands region of alberta this is challenging because the athabasca river is incised directly into bitumen saturated sands of the mcmurray formation and other saline cretaceous and devonian formations this study compares the geochemical and isotopic composition of porewater sampled from the alluvial sediment beneath the athabasca river with regional groundwater data to identify the geological origin of these saline groundwaters and improve characterization of natural background sources of solutes entering the athabasca river terrain conductivity surveys conducted along the athabasca river were used to identify areas with evidence of saline groundwater discharge porewater samples were obtained from the alluvial sediment using drive point piezometers installed between 1 and 3 m below the water sediment interface and were analyzed for 18o 2h 34s so4 18o so4 87sr 86sr 13c dic 13c doc 3h and 14c the porewater in the alluvial sediment showed variable degrees of mixing with the overlying athabasca river water but the geochemical and isotopic composition in zones 1 3 and 5 are consistent with discharge of saline groundwater from cretaceous or devonian units the low percentages of modern carbon and 18o 2h 34s so4 18o so4 and 87sr 86sr signatures in the deepest porewater samples from zones 1 3 and 5 indicate glaciogenic water with high total dissolved solids originating from devonian sourced solutes theses saline groundwater discharge zones occur where higher horizontal hydraulic gradients coincide with areas of higher salinity in the adjacent cretaceous and devonian aquifers and areas with vertical connectivity with underlying devonian aquifers the results of this study demonstrate the influence of groundwater surface water interactions and saline bedrock formation water discharge to water quality along some reaches of the athabasca river which need to be considered in monitoring and water management strategies

influence of saline groundwater discharge on river water chemistry in the athabasca oil sands region a chloride stable isotope and mass balance approach abstract a chloride mass and stable isotope 37 cl balance approach was employed to calculate the effect of saline groundwater discharge into the athabasca and clearwater rivers in the athabasca oil sands region aosr in north eastern alberta canada saline groundwater affected by halite carbonate and anhydrite dissolution discharges na cl type water with total dissolved solids tds up to 51 700 mg l from exposed devonian and cretaceous units in the river valleys in this area in this study nine springs discharging groundwater with a median cl concentration of 9800 mg l were sampled and chloride stable isotope ratios were determined with 37 cl values ranging from 0 2 to 1 0 in contrast river waters had historical monthly median cl concentrations between 5 9 and 49 5 mg l and 37 cl values between 2 2 and 1 4 the discharge rate of saline groundwater was calculated to be 100 20 l s into the clearwater river and 134 68 l s into the athabasca river the chemical composition and discharge rates of saline groundwater were used to estimate its contribution to the mass fluxes of major ions metals and pahs in the athabasca and clearwater rivers overall saline groundwater contributed less than 0 2 of river discharge but 0 04 39 of major ion concentrations in the rivers with highest contributions under winter low flow conditions in the clearwater river saline groundwater contributed 23 39 of average monthly cl flux and 18 32 of average monthly na flux for the same major ion fluxes in the athabasca river saline groundwater contributed 12 18 and 6 12 respectively the influence of saline groundwater discharge on the mass flux of trace elements in the rivers was found to be negligible contributing less than 1 of river fluxes of cu ni pb and zn similarly the influence on mass flux of pahs in the rivers was found to be negligible

mesoscale structure in the megalopolitan snowstorm of 11 12 february 1983 part iii a large amplitude gravity wave abstract a large amplitude singular gravity wave is studied through the analysis of hourly observations radar and satellite data and observations of cloud to ground lightning flashes the wave activity was initiated just ahead of and to the left of the track of the major atlantic coast cyclone of 11 12 february 1983 the initial wave of depression was followed by a wave of elevation and finally a wake depression pressure amplitudes were several millibars the system propagated northeastward at 15 m s 1 accelerating to more than 25 m s 1 against increasing northeasterly flow in the lower troposphere surface northeasterlies increased and became gusty with the approach of the first pressure falls reaching a maximum at the pressure trough then abruptly weakening and backing as strong pressure increases were observed strong fluctuations in column total condensation rate and radar reflectivity occurred with the passage of the wave clustered lightning activity accompanied wave passage principally near

inverse modeling of annealing of fission tracks in apatite 2 application to the thermal history of the peace river arch region western canada sedimentary basin

geothermal gradients hydrodynamics and hydrocarbon occurrences alberta canada using coal rank data and the demonstrated genetic link between the present hydrodynamic regime and geothermal gradient pattern it is possible to reconstruct the geothermal history of alberta over the past 60 m y palinspastic adjustment for tectonic compression caused by the major laramide thrusting shows that the predeformation isoreflectance lines increased logarithmically with depth in the late paleocene the geothermal gradient was about 23 c km 1 25 f 100 ft in the eastern alberta plains compared to about 30 c km 1 65 f 100 ft in the western alberta plains a regional trend opposite to the post laramide trends reconstruction of the early eocene surface indicates western uplands with geothermal gradients as low as 21 c km 1 15 f 00 ft and eastern lowlands with geothermal gradients of 27 c km 1 5 f 100 ft compared to the present situation this represents an enhanced topographic surface and a subdued geothermal gradient pattern the genetic relations of topography water table elevation hydrodynamic regime and geothermal gradient pattern in both the early eocene and the present conform to a model developed for any compacted sedimentary basin with subaerial relief in this model on a regional scale high topographic areas have high water table elevations with correspondingly high potentiometric surfaces these areas control the regional recharge of cold meteoric water and hence have low geothermal gradients areas of medium elevation exhibit regional lateral flow and intermediate geothermal gradients regional topographic lows correspond with low potentiometric surfaces and the regional discharge of warm formation waters from deep in the basin results in high geothermal gradients local topographic featur s cause perturbations in this picture study of both the regional pattern and fine detail of the early eocene and present topographic surfaces and geothermal gradient patterns shows the validity of the model the result of the second laramide orogenic pulse was therefore to reverse the geothermal gradient pattern resulting mainly from compaction flow and to impose a topographically controlled hydrodynamic regime with flow in the same direction but with a 9 c km 0 5 f 100 ft decreased geothermal gradient in western alberta and a 4 c km 0 2 f 100 ft increased geothermal gradient in eastern alberta as erosion proceeded during the tertiary the entire alberta basin warmed up until the present temperature regime was attained study of some major hydrocarbon occurrences shows a genetic link between the hydrocarbon occurrence and the present fluid regime which itself is controlled by the present topography for at least the significant upper cretaceous shallow gas reserves in southeastern alberta however their position may already have been determined as early as the beginning of the eocene by the topographic surface at that time therefore the extent to which the present topographic surface is responsible for hydrocarbon accumulation through gravity induced cross formational flow remains unknown because this process was operative as long ago as the early eocene what does not ap ear to be in doubt is the fact that gravity induced cross formational flow does control the hydrodynamic regime which in turn influences the geothermal gradient pattern and the accumulation of hydrocarbons

possible effects of erosional changes of the topographic relief on pore pressures at depth formation fluid pressures are said to be anomalous or abnormal if they differ from hydrostatic for the depth considered explanations of the origin and maintenance of anomalies seldom include the possibility of delayed adjustment of subsurface pore pressures to erosional modifications of the topographic relief yet the present paper shows that it is entirely possible for subaerial erosion to generate pore pressure changes at great depths by cross formational energy transfer in realistic field conditions conversely pressures may survive changes in the topography and be in a transient state for hundreds to millions of years thus appearing anomalous at the time of observation according to calculations for the red earth region in alberta canada present pore pressures in the devonian immediately above the precambrian basement at a depth of approximately 1400 meters may have been induced originally by erosionally shaped topography during pliocene times 12 to 1 m y b p but be adjusting now to new boundary conditions created by the erosional exposure of the sub cretaceous unconformity a 12 adjustment may already have taken place during the last 300 thousand years leaving nearly 90 of pliocene age pressures to survive to date as slowly decaying transient pressure relicts of the geologic past in view of the possible erosional effects on pore pressures demonstrated in this paper the question of anachronous formation pressures may deserve consideration in problems related to deep basin hydrology including regional groundwater resource development migration and accumulation of hydrocarbons radioactive waste isolation dating of various geologic events and so on

the structure water budget and radiational features of a high latitude warm front abstract on 30 september 1994 an arctic low pressure system passed over the southern beaufort sea area of northern canada and research aircraft observations were made within and around the warm front of the storm this study is unique in that the warm front contained subzero centigrade temperatures across the entire frontal region the overall structure of the warm front and surrounding region was similar to midlatitude storms however the precipitation rates liquid water content magnitudes horizontal and vertical winds vertical wind shear turbulence and thermal advection were very weak in addition a low level jet and cloud bands were aligned parallel to the warm front near neutral stability occurred within and around the front and conditional symmetric instability was likely occurring a steep frontal region resulted from strong coriolis influences that in turn limited the amount of cloud and precipitation ahead of the system the precipitation efficiency of the storm was high 60 but is beli

mesoscale circulations forced by melting snow part ii application to meteorological features abstract various authors have proposed that the cooling associated with melting precipitation contributes significantly to the dynamics of mesoscale precipitation systems in this study we use the numerical model described in part i of this paper to investigate the effects of the cooling by melting mechanism in three specific situations rain snow boundaries the production of deep 0 c isothermal layers and the trailing stratiform region associated with mesoscale convective systems it is found that melting in the vicinity of a rain snow boundary produces a thermally indirect mesoscale vertical circulation that may be responsible for enhanced precipitation near a rain snow boundary melting in the presence of warm air advection above the melting layer and cold advection at and below it are necessary for producing deep 0 c layers within realistic times the dynamic effects of cooling associated with melting and evaporation in the stratiform region of a mature squall line system produce a mesoscale circul

multiscale structure and evolution of an oklahoma winter precipitation event abstract a significant winter precipitation event occurred on 8 9 march 1994 in oklahoma snow accumulations greater than 30 cm 12 in were measured within a narrow corridor in northern oklahoma on the synoptic scale and mesoscale a correspondence between large snow accumulations and 600 hpa frontogenesis was revealed the precipitation was formed above the cold frontal surface owing to midtropospheric ascent associated with the cross frontal circulation in a region of elevated conditional instability the location of such a narrow corridor of large accumulations was not however disclosed by any patterns in the radar reflectivity data indeed during this event an elongated maximum of snow accumulation was not associated with a persistent band of enhanced reflectivity and vice versa dual polarization and dual doppler radar data allowed for a novel analysis of winter precipitation processes and structures within the context of the larger scale diagnosis it was possible to identify in order of

frontogenesis and symmetric stability in a major new england snowstorm abstract synoptic and doppler radar data are used to study the roles of large scale frontogenetical forcing and of moist symmetric instability in the new england snowstorm of 5 6 december 1981 associated with an explosively intensifying cyclone offshore radar reflectivity patterns showed a tendency toward banded structure particularly near the leading northwestern edge of the storm only a minor portion of the snowfall however was associated with this pronounced bandedness from a set of constant pressure analyses the frontogenetical forcing was measured from the variation along the temperature gradient of the geostrophic wind component in the direction of this gradient over southeastern new england maximum forcing found near 500 mb at the outset of the storm descended to the layer between 850 and 700 mb 24 h later magnitudes were 3 7 10 10 deg m 1 s 1 observed rates of strengthening of temperature gradient were less than half this value implying relative adiabatic cooling in the rising

meteorological tower measurements of a surface cold front abstract measurements from the boulder atmospheric observatory meteorological research tower are used to describe the structure and physical processes of a strong surface cold front analysis reveals that the horizontal gradients in temperature and wind velocity at the front are concentrated within a 200 m distance and measured vertical velocities exceed 5 m s 1 at the leading edge of the front calculations with the miller frontogenesis equation show the magnitude and relative importance of cross frontal confluence versus differential vertical motion tilting in forcing frontogenesis

regional scale porosity and permeability variations peace river arch area alberta canada this study examines the large scale variability of porosity and permeability of the sedimentary rocks in the phanerozoic succession in the alberta part of the peace river arch area of the western canada sedimentary basin the study is based on about 450 000 core analyses at approximately 22 000 wells in an area of more than 165 000 km 2 plug scale porosity and permeability values are scaled up to the well scale by hydrostratigraphic unit resulting in two sets of about 16 000 values each for porosity and permeability unevenly distributed both areally and with depth the permeability frequency distributions are lognormal for most of the units or parts of the units the regional scale variability of porosity and permeability is quite high between 1 and 38 for porosity and 0 001 md and 3 d for permeability the clastic units of the foreland basin exhibit a relatively high correlation between permeability and porosity several areal trends and patterns are identified for groups of hydrostratigraphic units patterns that change gradually from one group to another it is hypothesized that the observed variability is caused by the dominance of the peace river arch carbonate deposition or compaction at various times throughout the evolution of the basin based on the predominant controlling factor the geological history can be divided into four periods arch influence during the early to middle devonian reefal carbonate deposition influence during the middle to late devonian passive margin influence during the late devonian to middle jurassic and orog nic influence since the middle jurassic

coupled fluid flow heat and mass transport and erosion in the alberta basin implications for the origin of the athabasca oil sands regional topography driven flow systems related to laramide tectonic rebound were simulated using two dimensional coupled fluid flow heat transport and solute transport numerical models to replicate present formation water salinity and temperature distributions and investigate the accumulation of the athabasca oil sands previous modelling of this system was replicated and it predicted repeated replacement of all basin formation water with freshwater during deposition of the oil sands due to high permeabilities to match present alberta basin temperature and salinity distributions model hydrostratigraphy permeabilities and heat fluxes were adjusted this revised model conducts fluids along the mannville aquifer rather than the upper devonian aquifer and replicates present salinity distributions assuming instantaneous uplift around 60 ma fluid fluxes in principal aquifers decrease by two orders of magnitude using new permeabilities resulting in primarily conductive heat transport thus genesis

on the width and motion of a rain snow boundary a rain snow boundary moves towards the adjacent rain region owing to the progressive cooling of the atmosphere caused by melting snow the dependence of the width and speed of the boundary on the initial lapse rate the size of the largest snowflake the snowflake density the precipitation rate and the horizontal temperature gradient is determined using a numerical model the dependence on relative humidity is explained qualitatively the results from these calculations predict speeds of about 0 5 m s 1 and widths of about 10 km after 2 days using reasonable values of the governing parameters in a precipitation rate of 1 mm h 1

deep 0 c isothermal layers within precipitation bands over southern ontario isothermal layers having a temperature of 0 c and depths up to 1 km were measured within two precipitation bands occurring within autumn storms over southern ontario across these layers wind shears up to 0 02 s 1 existed and aggregation led to particles up to 20 mm in diameter melting and evaporation are proposed as contributing to the development of the layers

observations of sar polarimetric parameters of lake and fast sea ice during the early growth phase abstract this study examines links between two sets of parameters obtained from radarsat 2 quad pol data and geophysical information of lake ice and landfast sea ice in the resolute bay area nunavut canada the first set includes the three orthogonal backscatter coefficients hh0 vv0 vh0 in addition to the total backscatter power span the second set includes polarimetric decomposition parameters obtained using cloude pottier and yamaguchi decomposition methods data were collected during the early freezing period from 20 september until 28 december 2017 meteorological and ice climatological data from the weather station of resolute bay were used to facilitate this task ice thickness and salinity were obtained from established empirical models results show that single bounce and multiple bounce scattering mechanisms are active in lake ice during the entire freezing period while multiple bounce scattering is active in sea ice only during the initial freezing backscatter parameters can be used to determine the thickness of lake ice up to any depth while both backscatter and the tested decomposition parameters are related to the thickness of young sea ice 0 6 is found to be associated with comparable single and multiple bounce scattering mechanisms hence can be used to identify new ice orthogonal backscatter coefficients and polarimetric decomposition parameters provide different information yet their combination offers clues to better identify ice conditions and investigate questions about scattering mechanisms

subglacial recharge into the western canada sedimentary basin impact of pleistocene glaciation on basin hydrodynamics brine springs discharging from devonian carbonates of the western canada sedimentary basin have distinct water chemistry from brines in laterally equivalent units deeper in the basin stable isotope data suggest that the brine springs originated as pleistocene meltwater these waters are interpreted to originate as an influx of subglacial meltwater related to a reversal of the basin scale flow system caused by the overriding ice sheet esker distribution shows a notable relationship between shield and sedimentary rocks an integrated sedimentary basin ice sheet model supports the interpretation that high permeability carbonate units acted as preferential subglacial drains that in turn affected esker development the fluid flow history of the western canada sedimentary basin is characterized by back and forth movement through geological time in response to changing boundary conditions modern day flow systems may not then be indicative of historic movement of economic fluids through the basin

the effect of along front temperature variation in a two dimensional primitive equation model of surface frontogenesis abstract the development of frontal zones is examined in a two dimensional primitive equation model of frontogenesis formulated for dry nearly adiabatic and inviscid conditions the model results are interpreted in the context of the general problem of determining the dynamical properties of cold and warm fronts the central hypothesis attributable to eliassen is that cold and warm fronts may be distinguished by the orientation of the cross front thermal wind component and the sense of the associated along front temperature variation three simulations comprising confluent forcing geostrophic contraction in the cross front direction and differing initial specifications of the along front potential temperature gradient are examined in detail in the first simulation referred to as the pure confluence case the along front potential temperature gradient is set to zero establishing a control for specifying along front potential temperature variations respectively characteristic of cold and warm fronts