numerical experiments on cloud streets in the lee of island arcs during cold air outbreaks 1 numerous clouds streets often appear in the lee of island arcs during cold air outbreak these clouds are quite similar each other in shape and appearance we found that two different kinds of cloud streets are coexistent in them one is formed by a mountain and another is formed by the temperature contrast between islands and the sea since difference in the characteristics between them is small it is difficult to simply discriminate by satellite images however two kinds of the cloud streets can be observationally classified by the statistics of the satellite images with the help of numerical experiments

detrital carbonate peaks on the labrador shelf a 13 7 ka template for freshwater forcing from the hudson strait outlet of the laurentide ice sheet into the subpolar gyre abstract the laurentide ice sheet lis was a large dynamic ice sheet in the early holocene the glacial events through hudson strait leading to its eventual demise are recorded in the well dated labrador shelf core md99 2236 from the cartwright saddle we develop a detailed history of the timing of ice sheet discharge events from the hudson strait outlet of the lis during the holocene using high resolution detrital carbonate ice rafted detritus ird 18o and sediment color data eight detrital carbonate peaks dcps associated with ird peaks and light oxygen isotope events punctuate the md99 2236 record between 11 5 and 8 0 ka we use the stratigraphy of the dcps developed from md99 2236 to select the appropriate r to calibrate the ages of recorded glacial events in hudson bay and hudson strait such that they match the dcps in md99 2236 we associate the eight dcps with h0 gold cove advance noble inlet advance initial retreat of the hudson strait ice stream hsis from hudson strait opening of the tyrrell sea and drainage of glacial lakes agassiz and ojibway the opening of foxe channel and retreat of glacial ice from foxe basin are represented by a shoulder in the carbonate data r of 350 years applied to the radiocarbon ages constraining glacial events h0 through the opening of the tyrell sea provided the best match with the md99 2236 dcps r values and ages from the literature are used for the younger events a very close age match was achieved between the 8 2 ka cold event in the greenland ice cores dcp7 8 15 ka bp and the drainage of glacial lakes agassiz and ojibway our stratigraphic comparison between the dcps in md99 2236 and the calibrated ages of hudson strait bay deglacial events shows that the retreat of the hsis the opening of the tyrell sea and the catastrophic drainage of glacial lakes agassiz and ojibway at 8 2 ka are separate events that have been combined in previous estimates of the timing of the 8 2 ka event from marine records sw iceland shelf core md99 2256 documents freshwater entrainment into the subpolar gyre from the hudson strait outlet via the labrador north atlantic and irminger currents the timing of freshwater release from the lis hudson strait outlet in md99 2236 matches evidence for freshwater forcing and lis icebergs carrying foreign minerals to the sw iceland shelf between 11 5 and 8 2 ka the congruency of these records supports the conclusion of the entrainment of freshwater from the retreat of the lis through hudson strait into the subpolar gyre and provides specific time periods when pulses of lis freshwater were present to influence climate

the owles iop2b lake effect snowstorm dynamics of the secondary circulation abstractintense lake effect snowfall results from a long lake axis parallel llap precipitation band that often forms when the flow is parallel to the long axis of an elongated body of water such as lake ontario the intensity and persistence of the localized precipitation along the downwind shore and farther inland suggests the presence of a secondary circulation that helps organize such a band and maintain it for some time as the circulation is advected inland unique airborne vertical plane dual doppler radar data are used here to document this secondary circulation in a deep well organized llap band observed during intensive observing period iop 2b of the ontario winter lake effect systems owles field campaign the circulation centered on a convective updraft intensified toward the downwind shore and only gradually weakened inland the question arises as to what sustains such a circulation in the vertical plane across the llap band wrf model simulations indicate that the primary llap band a

the quaternary geology of the labrador shelf the regional distribution of glacial and postglacial sediments on the labrador shelf was mapped by medium and high resolution seismics and shows a succession of tills that extend to the continental shelf edge at approximately 600 m the uppermost of these tills is less laterally extensive and does not occur on the labrador shelf bank tops in water depths less than 160 m we infer that the last glacial episode was less extensive than the preceding ones glaciomarine stratified silts and postglacial muds are found overlying the upper till in the deep basins that separate the banks the upper till glaciomarine silts and postglacial muds are interpreted to constitute one complete deglacial cycle radiocarbon age determination suggests this deglacial sequence began at approximately 20 000 years bp on the northernmost labrador shelf and hudson strait seismic evidence indicates a late glacial readvance locally deposited a till that overlies the glaciomarine sediments associated with the last glacial advance

transgressive depositional systems of the mississippi delta plain a model for barrier shoreline and shelf sand development abstract depositional sequences generated in the mississippi river delta plain consist of a regressive and a transgressive component the transgressive component has been considerably less studied but accounts for the majority of the surface area on the lower mississippi river delta plain and up to 50 percent of the total sequence thickness in shallow water deltas the development and preservation of transgressive depositional systems in abandoned delta complexes follows the process of transgressive submergence in which the horizontal component of reworking occurs during shoreface retreat combined with a vertical component of submergence acting to preserve the sequence the evolution of transgressive depositional systems in each of the abandoned holocene mississippi river delta complex s can be summarized in a three stage model beginning with stage 1 an erosional headland and flanking barriers in this stage regressive sand deposits contained within abandoned deltaic headlands are reworked by the eroding shoreface and dispersed longshore into contiguous flanking barriers enclosing restricted interdistributary bays submergence of the delta plain during relative sea level rise generates an intradeltaic lagoon separating the former stage 1 sand body from the shoreline forming stage 2 a transgressive barrier island arc the landward migrating barrier island arc is unable to keep pace with relative sea level rise and the retreating mainland shoreline resulting in submergence and the formation of stage 3 an inner shelf shoal following submergence the former barrier island arc sand body continues to be reworked into a marine sand body on the inner continental shelf during stage 3 this sequence of coastal evolution provides direct evidence of barrier island formation with each stage producing a distinctive stratigraphic signature the current sea level rise models of shoreface retreat and in place drowning developed for the u s atlantic continental shelf do not adequately explain either the morphology or the stratigraphy of transgressive mississippi river delta sand bodies current models of mississippi deltaic stratigraphy emphasize the deep water artificially maintained balize delta which differs considerably from the shallow water shelf phase delta complexes that are the primary depositional constituents of he holocene mississippi river delta plain

recognition and delineation of paleokarst zones by the use of wireline logs in the bitumen saturated upper devonian grosmont formation of northeastern alberta canada the upper devonian grosmont formation in northeastern alberta canada is a shallow marine carbonate platform complex that was subaerially exposed for hundreds of millions of years between the mississippian and cretaceous during this lengthy exposure period an extensive karst system developed that is characterized by an irregular erosional surface meter size several feet dissolution cavities collapse breccias sinkholes paleosols and fractures the karsted grosmont formation which contains giant reserves of bitumen subcrops beneath cretaceous clastic sediments of the giant athabasca tar sands deposit the paleokarst in the grosmont formation can be recognized on wireline logs in relatively nonargillaceous carbonate intervals 30 api units on the gamma ray log as excursions of the caliper log off scale neutron density porosity readings and severe cycle skipping of the acoustic log the paleokarst is more prevalent in the upper units of the grosmont formation and the effects of karstification decrease toward stratigraphically older and deeper units the paleokarst usually occurs within 35 m 115 ft of the erosional surface the reservoir properties of the grosmont formation e g thickness porosity permeability and seal effectiveness are significantly influenced by karstification depending upon the location karstification has either benefited or degraded the reservoir characteristics benefits include porosity values greater than 40 up to 100 in caverns and permeability values of 30 000 md in severely fractured intervals detrimental reservoir characteristics include erosion porosity and permeability reduction and seal ineffectiveness

regional scale porosity and permeability variations in upper devonian leduc buildups implications for reservoir development and prediction in carbonates upper devonian carbonate rocks of the rimbey meadowbrook reef trend in the subsurface of central alberta are characterized by a wide range of porosity and permeability values dolostones show the highest values of absolute and average horizontal and vertical permeability for all rock types horizontal permeability averages tens of times to several hundred times the vertical permeability if considered irrespective of burial depth limestones and dolomitic limestones are more porous than dolostones there is an overall decrease of porosity and permeability in leduc formation carbonates with increasing burial depth and thermal maturity along the reef trend at relatively shallow burial depths 2000 m dolostones are significantly more porous and permeable than limestones dolostones appear to retain their porosity and permeability much better than limestones during burial indicating that dolostones are more resistant to porosity and permeability reducing processes particularly pressure solution thus reservoir quality in dolostone reservoirs decreases less severely with depth in addition porosity enhancement in dolostones by leaching in the burial environment during and after dolomitization is important although these significant relationships arenot new concepts they appear to be underappreciated the better porosity and permeability of dolostones relative to limestones at greater depths is of economic significance for exploration in upper devonian carbonates of the deep alberta basin and probably other carbonate areas where reservoirs are mostly found in dolostones and where limestones have a low reservoir potential and pose a considerable exploration risk the best reservoir potential in the leduc formation of the deep alberta basin occurs in dolomitized buildups that were connected to a regional conduit system

genesis and development mechanisms of a polar mesocyclone over the japan sea abstracta polar mesocyclone pmc observed over the japan sea on 30 december 2010 was studied using a nonhydrostatic mesoscale numerical model with a horizontal resolution of 2 km the numerical simulation successfully reproduced the observed life cycle of the pmc the results of the numerical simulation suggest that the life cycle of the pmc may be divided into three stages an early development stage in which a number of small vortices appear in a shear zone a late development stage which is characterized by the merger of vortices and the formation of a few larger vortices and a mature stage in which only a single pmc is present during the early development stage vortices are generated in the shear zones of strong updrafts in discrete cumulus convection cells in contrast during the late development stage the vortices develop as a result of barotropic instability in the shear zone a cloud free eye and spiral cloud bands accompany the mature stage of a simulated pmc a warm core structure also

an assessment of analytical techniques for the size analysis of fine grained sediments abstract an evaluation of techniques for the size analysis of fine grained sediments revealed that the malvern laser sizer e3600 electrozone particle counter model 112 micromeritics sedigraph 5000e and hydrophotometer work well for the analysis of sorted silt differences in results may be attributed to the particle property being measured by each instrument the malvern laser sizer and electrozone particle counter are sizing techniques the hydrophotometer and sedigraph determine sedimentation diameter through particle settling there was less agreement among these instruments for unsorted natural sediments containing greater than 15 percent clay by weight clay content of less than or equal to 8 percent does not appear to decrease the resolution of silt sized particles

observation of coexisting mesoscale lake effect vortices over the western great lakes mesoscale vortices are one of several types of wintertime lake effect structures that are observed over the great lakes region as cold arctic air is rapidly modified from below by warm lake waters these vortices are thought to occur less frequently than other lake effect structures such as wind parallel snowbands e g kristovich 1993 which are responsible for greater than half of the yearly snowfall downwind of the western great lakes kelly 1986 and more intense shore parallel snowbands which can produce localized heavy snowfalls e g braham 1983 through the examination of visible satellite imagery forbes and merritt 1984 found 14 cases of mesoscale vortex formation over the great lakes in the years 1978 82 this suggests that on average a mesoscale vortex will occur within the great lakes region less than four times a winter during an early winter lakeeffect event on 13 november 1995 intense land breeze circulations and four mesoscale vortices 50 km diameter developed over lakes superior huron and michigan simultaneously fig 1 this unique observation of coexisting lake effect vortices over the western great lakes has not previously been reported in the literature and suggests that atmospheric conditions favorable for vortex development were widespread throughout the region previous cases have typically observed a single vortex suggesting that favorable meteorological conditions were localized the author is aware of only two other reported observations of simultaneous mesoscale vortices within the great lakes region schoenberger 1986 pitts et al 1977 however the lake effect vortices that schoenberger 1986 and

airborne radar observations of lake effect snowbands over the new york finger lakes abstractthe vast majority of lake effect snow research throughout the years has focused on the north american great lakes since they are often associated with strong lake effect events that produce heavy downstream snowfall this study investigates a lake effect snow event that instead occurred over two smaller lakes the new york finger lakes which are just o 5 km wide and o 50 km long a pair of well defined snowbands that formed over seneca and cayuga lakes the two largest of the finger lakes were sampled from above by a vertically pointing doppler radar and lidar on board the university of wyoming king air uwka with typical widths matching the widths of the lakes and depths of less than 1000 m the long lake axis parallel bands were actually quite intense for their size for example updrafts of 2 3 m s 1 or greater within the band cores were common and reflectivity occasionally exceeded 5 dbz airborne dual doppler data show that both bands were sometimes accompanied by a well defined therm

high resolution seismic stratigraphy of late quaternary deposits in manitounouk sound northern quebec effects of rapid postglacial emergence manitounouk sound contains a succession of postglacial deposits consisting of three acoustic units separated by disconformities from base to top these are 1 a stratified draped unit interpreted as of glaciolacustrine and glaciomarine origin 2 an onlapping basin fill unit of thick transparent beds interpreted as gravity flow deposits and 3 a divergent fill unit of stratified and transparent modern marine deposits the gravity flow deposits of unit 2 pass laterally into slide scars that truncate unit 1 pollen and dinoflagellate analysis of cores correlated with the acoustic sections indicate that unit 1 is of early holocene age and confirms a glaciomarine environment unit 3 contains modern assemblages of pollen and dinoflagellates the slide scar and gravity flow deposits of unit 2 correspond to the period of transition from glaciomarine to modern conditions and are interpreted to result from a period of relatively intense earthquake activity due to stress release along faults during or shortly

synthesis and model of formation water flow alberta basin canada based on a large amount of publicly available data several studies have previously examined the flow of formation waters in different parts of the alberta basin offering various interpretations as to the causes of the observed pressure regime and flow pattern however there has been no synthesis of these diverse studies on a basin wide basis accordingly these studies are critically reviewed in this paper and synthesized in a new basin scale model of the flow of formation waters in the alberta basin the proposed regional scale model has significant implications for understanding hydrocarbon migration pathways ore genesis the geothermal regime and deep waste disposal in the alberta basin several flow systems each one driven by a different mechanism are identified together with the main processes leading to the nonhydrostatic pressures observed in the basin two megahydrostratigraphic successions and associated flow systems are recognized the first succession corresponds to the pre cretaceous passive margin stage of basin development and consists of thick carbonate dominated aquifer systems separated by shaly aquitards and evaporitic aquicludes a northeastward basin scale flow system is driven by basin topography with recharge in montana and discharge in northeastern alberta southwest to northeast regional scale flow adjacent to the fold and thrust belt is probably the result of past tectonic processes the salinity of formation water in pre cretaceous aquifers is high and generally increases both northward and with depth this variability is the result of increased water rock reactions mineral solubility with increased temperatu e and of incomplete flushing by meteoric water as a result of salinity variations flow retarding buoyancy effects can be important the second megahydrostratigraphic succession corresponds to the post jurassic foreland stage of basin evolution and consists of thick shaly aquitard systems and relatively thin sandstone aquifers in the southwestern part of the basin flow in isolated aquifers is driven southwestward by erosional rebound in the thick intervening shales downdip toward the fold and thrust belt the salinity of formation waters in the post jurassic aquifers is low mixing of waters and interference between the major flow systems takes place along the pre cretaceous unconformity where successively older pre cretaceous aquifers subcrop from west to east flow in shallow lo al systems at the top of the sedimentary succession is driven by local topography

dynamics of the laurentide ice sheet in hudson bay canada abstract interpretation of sidescan sonar and high resolution sub bottom seismic data from hudson bay has led to the development of a model for final disintegration of the laurentide ice sheet the well preserved geomorphic features observed from the bay floor are similar to subaerially exposed glaciogenic features observed around the perimeter of hudson bay and can be related to the following three paleoenvironments subglacial erosion deposition ice margin deposition and reworking and post glacial reworking and burial subglacial features observed include fluted terrains with superimposed rogen moraines relief attributed to ice surging eskers subglacial channels and dead ice topography de geer moraines and recessional moraine complexes indicate the mechanism and orientation of ice breakup retreat the orientations of these features are locally consistent with regional trends indicating the overall direction of ice sheet flow and retreat during the last phase of the laurentide ice sheet subglacial channel complexes incised into the till and bedrock and high energy bedforms deposited on the till surface occur in present day water depths down to 160 m due to isostatic depression these could have been as much as 315 m deeper at the time of formation they indicate a wet based glacier with high energy subglacial drainage during the late phases of ice retreat the sidescan sonar data also reveal numerous zones of distinctive morphology attributed to ice breakup and post glacial processes cross cutting relationships allow the determination of the relative ages of these zones from oldest to youngest these zones are interpreted to represent scouring of the bedrock and overburden by the remnants of the ice sheet seafloor scouring by tabular icebergs which moved in a tidally induced arcuate pattern or under the influence of massive glacial lake outflows development of dead ice topography under residual ice masses and random iceberg scouring by smaller icebergs restricted to present day water depths of less than 180 m recently published reconstructions of the collapse of the laurentide ice sheet based on dated quaternary sections on land suggest that the bay was rapidly deglaciated in approximately 400 years the well preserved and distinctive glaciogenic and stratigraphic indicators observed from the bay floor suggest that they were formed by a succession of mechanisms which were too short lived to obliterate the underlying evidence of deglaciation this supports the interpretation of extremely rapid deglaciation of hudson bay and points out that subsequent marine processes have not been sufficient to obliterate the glacial features

granulometric characterization and evaluation of annually banded mid holocene estuarine silts welsh severn estuary uk coastal change sea level and climate abstract holocene silts salt marshes and highest intertidal supratidal peats are superbly exposed on a 15 km coastal transect which reveals two laterally extensive units of annually banded silts beds 3 7 associated with three transgressive regressive silt peat cycles early sixth early fourth millennium bc bed 3 in places is concordantly and gradationally related to peats above and below but in others transgresses older strata bed 7 also grades up into peat but everywhere overlies a discordance the banding in bed 3 at three main and two minor sites was resolved and characterized texturally at high resolution 2 5 5 mm contiguous slices using laser granulometry ls230 with pids and a comprehensive scheme of data assessment most of bed 3 formed very rapidly at peak values of several tens of millimetres annually in accordance with modelled effects of sea level fluctuations on mature marshes bed concordant and gradational and on marshes growing up after coastal erosion and retreat bed with discordant base using data from the modern severn estuary the textural contrast within bands and its variation between bands points to a variable but overall milder mid holocene climate than today the inter annual variability affected marsh dynamics as shown by the behaviour of the finely divided plant tissues present given local calibration the methodology is applicable to other tidal systems with banded silts in britain and mainland northwest europe

an integrative geothermal resource assessment study for the siliciclastic granite wash unit northwestern alberta canada this study explores the siliciclastic granite wash unit in northwestern alberta as a potential geothermal reservoir the approach covers regional 3d structural geological modelling of a 90 km 70 km area based on well log and legacy 2d seismic data the fault strike was interpreted from lineaments which were identified with the refined trend surface analysis method the stress state of the granite wash reservoirs was determined by an integrated approach of 3d fault modelling stress ratio definition based on frictional constraints and slip tendency analysis the results show that the best site for a geothermal application is located in the southwestern study area where the highest temperatures above 70 c coincide with the largest thickness above 20 m and zones of elevated porosity and permeability the integrated stress analysis indicates an in situ stress regime from normal to strike slip faulting maintaining a non critically stressed reservoir or faults therein assuming a friction coefficient of 0 7 the granite wash reservoirs could be used for heating of greenhouses domestic warm water provision and district heating

the analysis of grain size measurements by sieving and settling tube techniques abstract analyses of grain size measurements by sieving and settling tube techniques generally represent the grain size as sieve diameters and sedimentation diameters artificially replacing the natural irregular grains with equivalent spheres depending on the true grain shape this of course deviates considerably from their actual dimensions the present study reexamines the technique of sieving reconfirming that this approach sorts the grains by shape as well as by size the grain s intermediate axial diameter is the main controlling factor in its passage through sieve screens and the analysis procedure of this study yields the distribution of grain intermediate diameters from the sieving measurements rather than the sieve diameter this permits a direct comparison with size dist ibutions obtained by settling tube analyses in that an analysis procedure is also presented where measured settling velocities are similarly converted into grain intermediate diameters rather than to sedimentation diameters of spheres comparisons of sieving and settling tube analyses of the same sand sample are found generally to yield nearly the same distributions of intermediate grain diameters the remaining differences are due primarily to the heavy mineral contents of the sands unusual grains such as micas some uncertainties in the evaluation of settling velocities of fine grained natural sediments and in our particular case possible errors associated with the sedimentation balance we employed

the mackenzie delta sedimentary processes and facies of a high latitude fine grained delta the mackenzie delta is a large fine grained delta deposited in a cold arctic setting the delta has been constructed upon a flooding surface developed on a previous shelf phase delta there are three principal depositional zones the subaerial delta plain the distributary channel mouth region and the subaqeous delta the subaerial delta plain is characterized by an anastomosing system of high sinuosity channels and extensive thermokarst lake development this region is greatly influenced by the annual cycle of seasonal processes including winter freezing of sediments and channels ice jamming and flooding in the early spring and declining river stage during the summer and autumn deposition occurs on channel levees and in thermokarst lakes during flood events and is commonly rhythmic in nature with discrete annual beds being distinguishable in the channel mouth environment deposition is dominated by landward accretion and aggradation of mouth bars during river and storm surge induced flood events the subaqeous delta is characterized by a shallow water platform and a gentle offshore slope sediment bypassing of the shallow water platform is efficient as a result of the presence of incised submarine channels and the predominance of suspension transport of fine grained sediments facies of the shallow platform include silty sand with climbing ripple lamination offshore facies are dominated by seaward fining fine sand to silt tempestites sea ice scouring and sediment deformation are common beyond 10 m water depth where bioturbated muds are the predominant facies the low angle profile of the shallow water platform is interpreted to be the combined response of a fine grained delta to 1 storm sediment dispersal 2 autoretreat as a result of the increasing subaerial and subaqeous area of deposition as the delta progrades out of its glacial valley 3 limited water depth above the underlying flooding surface and 4 efficient nearshore bypassing of sediment through subice channels at the peak of spring discharge several indicators of the cold climate can be used as criteria for the interpretation of ancient successions including thermokarst lake development submarine channel scours freeze thaw deformation and ice scour deformation structures permafrost inhibits compaction subsidence and together with the shallow water setting also limits autocyclic lobe switching the cold climate can thus influence stratal architecture by favouring the development of regional scale clinoform sets rather than multiple smaller scale lobes separated by autocyclic flooding surfaces

climatology of polar mesocyclones over the sea of japan using a new objective tracking method abstractpolar mesocyclones pmcs are mesoscale cyclonic vortices that develop poleward of the main polar front this article reports on a new algorithm for the objective tracking of pmcs including meso scale vortices which will facilitate the study of their climatology the algorithm is based mainly on the vorticity field and consists of three parts the identification of vortices the connection of vortices at consecutive time steps and discrimination between pmcs and synoptic scale disturbances the objective tracking method was applied to mesoscale analysis ma data provided by the japan meteorological agency which has a horizontal resolution of 5 km the detected tracks of pmcs were confirmed by subjective analysis of the ma data and satellite images the method used here to discriminate between pmcs and synoptic scale disturbances differs from that used in previous studies which is based on the difference between the sea surface temperature and the temperature at 500 hpa but gives a consist

tidal marsh stratigraphy sea level change and large earthquakes i a 5000 year record in washington u s a abstract many of the estuaries of the pacific northwest of the u s a and canada contain stratigraphic sequences typified by alternating peat mud couplets recent studies in this region interpret such couplets as the product of repeated large magnitude s or 9 earthquakes on the cascadia subduction zone the resultant pattern of land level movements is described by a model the earthquake deformation cycle of coseismic land subsidence followed by land uplift during interseismic strain accumulation however peat mud couplets similar to those recorded in the pacific northwest are found on other less tectonically active temperate latitude coasts such as northwest europe and the atlantic coast of the u s a where they have been interpreted as the product of non seismic coastal processes in this paper we apply the methods and scientific framework common to sea level investigations in northwest europe to a sequence of peat mud couplets recorded in the lower johns river an estuary in southern washington to provide a test of the earthquake deformation cycle stratigraphic investigations of the intertidal sediments along the lower johns river using lithological pollen diatom and foraminiferal data show evidence for eight coastal submergence events during the last 5000 years to evaluate the earthquake deformation cycle we assess the lateral extent of peat mud couplets the synchroneity of submergence the presence of tsunami deposits accompanying submergence and the suddenness and amount of submergence each submergence is shown to be accompanied by changes in coastal sedimentation broadly commensurate with those predicted by the earthquake deformation cycle demonstrating the continued intermittent seismic activity of the cascadia subduction zone throughout the mid and late holocene quantitative analyses of contemporary and fossil biostratigraphic data using twinspan and detrended correspondence analysis enable us to estimate the magnitude of submergence accompanying each peat mud couplet one event was accompanied by submergence of about 1 5 m or more four events by intermediate submergence of about 1 0 5 m and a further three events by submergence of

numerical simulation of transitions in boundary layer convective structures in a lake effect snow event abstract numerical simulations are used to study transitions between boundary layer rolls and more cellular convective structures observed during a lake effect snow event over lake michigan on 17 december 1983 weak lake effect nonroll convection was observed near the eastern downwind shore preceding passage of a secondary cold front after frontal passage horizontal wind speeds in the convective boundary layer increased with subsequent development of linear convective patterns thereafter the convective pattern became more three dimensional as low level wind speeds decreased little directional shear was observed in any of the wind profiles numerical simulations with the advanced regional prediction system model were initialized with an upwind sounding and radar derived wind profiles corresponding to each of the three convective structure regimes model derived reflectivity fields were in good agreement with the observed regimes these simulations differed primarily in the initial wind speed profiles

lake effect mode and precipitation enhancement over the tug hill plateau during owles iop2b abstractimproved understanding of the influence of orography on lake effect storms is crucial for weather forecasting in many lake effect regions the tug hill plateau of northern new york hereafter tug hill rising 500 m above eastern lake ontario experiences some of the most intense snowstorms in the world herein the authors investigate the enhancement of lake effect snowfall over tug hill during iop2b of the ontario winter lake effect systems owles field campaign during the 24 h study period total liquid precipitation equivalent along the axis of maximum precipitation increased from 33 5 mm at a lowland 145 m msl site to 62 5 mm at an upland 385 m msl site the latter yielding 101 5 cm of snow however the ratio of upland to lowland precipitation or orographic ratio varied with the mode of lake effect precipitation strongly organized long lake axis parallel bands some of which formed in association with the approach or passage of upper level short wave troughs produced the highest pre

synthetic dual doppler analysis of a winter mesoscale vortex abstract this article presents a detailed examination of the kinematic structure and evolution of the 5 december 1997 winter mesoscale vortex in the vicinity of lake michigan using the synthetic dual doppler sdd technique when such a mesoscale event propagates a distance large enough that the viewing angle from a single doppler radar changes by about 30 and the circulation is sufficiently steady during this time period then the sdd method can reveal reliable details about the circulation one such detail of the observed vortex was a pattern of convergence and divergence associated with radial bands where heavier snowfall was located another was the steadiness and vertical coherence of the derived vorticity and convergence patterns within the cyclonic circulation on 5 december 1997 the observed reflectivity field remained remarkably steady for nearly 2 5 h as the vortex moved southeastward allowing for the application of the sdd technique the reflectivity field exhibited a pronounced asymmetric c

diagenetic processes influencing porosity in sandstones from the triassic buntsandstein of the iberian range spain abstract sandstones of the triassic buntsandstein of spain were studied in an attempt to quantify effects of diagenetic processes such as compaction cementation and leaching on reservoir properties samples were taken from shell well siguenza 44 3 some 110 km northeast of madrid drilled on the siguenza high in the iberian range the sandstones are arkoses to sublitharenites of a typical triassic redbed facies characteristic of the whole region the present day depth of the base buntsandstein is 538 m whilst a maximum burial depth of ca 2600 m was estimated from vitrinite reflectance 0 94 to 1 14 kaolinite temperature 76 c and illite crystallinity kuebler index 4 9 from an estimated average initial porosity of 38 porosity was reduced to the present value of 13 the strongest process to reduce porosity was found to be mechanical compaction causing a loss of 15 followed by chemical compaction pressure solution with a loss of about 6 the cement 11 4 r v apparently reduced the initial porosity by about only 5 early carbonate and sulphate cements are interpreted to have stabili sed the rock framework working against mechanical compaction and pressure solution this is supported by an increase in sutured grain contacts where early cements are absent or rare the later quartz cement interpreted to be largely the product from pressure solution has reduced porosity in a ratio of 0 5 1 this suggests that compaction continued after the formation of the late quartz cement although leaching was observed especially in feldspar grains clay and k feldspar neomorphosis is interpreted to have counteracted the formation of substantial secondary porosity permeability in the buntsandstein is generally low average 17 4 md and has been strongly affected by the alteration of feldspars to clay causing a wide range of permeability from 0 11 to 73 0 md

the owles iop2b lake effect snowstorm shoreline geometry and the mesoscale forcing of precipitation abstractlong lake axis parallel llap lake effect precipitation systems that form when the flow is parallel to the long axis of an elongated body of water frequently produce intense highly localized snowfall conceptual models of these llap systems typically emphasize the role of thermally forced land breezes from the flanking shorelines with low level convergence and ascent centered near the lake axis in reality other factors such as shoreline geometry and differential surface roughness can strongly influence llap systems here a wrf model simulation is used to examine the mesoscale forcing of lake effect precipitation over lake ontario during iop2b of the ontario winter lake effect systems owles field campaign in the simulation the large scale flow shoreline geometry and differential surface heating and roughness contribute to the development of three major airmass boundaries the first is a land breeze front that forms along a bulge in the south shoreline between st catharines ontario can

climate change and recent sedimentation in nastapoka sound eastern coast of hudson bay in an attempt to determine to what extent the impact of recent climate changes that occurred east of hudson bay including important reduction of areas in permafrost had on the coastal marine environment a series of shallow cores were extracted from the seabed off the mouth of the sheldrake river in nastapoka sound a total of 25 cores were taken in april 2009 from the ice cover a preliminary seafloor map was first done to help in the selection of the coring sites nastapoka sound has a complex subaqueous relief formed of asymmetric ridges and deep basins after preliminary sedimentological analyses six of the cores were selected for physical and chronological analyses 14c 210pb and 137cs dating among them three were selected for elemental c n oc tn and isotopic 13c 15n analyses to identify sedimentary organic matter sources sedimentation processes are complex and are primarily driven by bottom currents this is confirmed by the absence of a clay fraction in several cores some erosi

the cambrian basal sandstone unit in central alberta an investigation of temperature distribution petrography and hydraulic and geomechanical properties of a deep saline aquifer recent geothermal exploration indicated that the cambrian basal sandstone unit bsu in central alberta could be a potential target formation for geothermal heat production due to its depth and extent although several studies showed that the bsu in the shallower western canada sedimentary basin wcsb has good reservoir properties almost no information exists from the deeper wcsb this study investigated the petrography of the bsu in central alberta with help of drill cores and thin sections from six wells porosity and permeability as important reservoir parameters for geothermal utilization were determined by core testing the average porosity and permeability of the bsu is 10 and 1 10 14 m2 respectively a zone of high porosity and permeability was identified in a well located in the northern part of the study area this study presents the first published geomechanical tests of the bsu which were obtained as input parameters for the simulation of hydraulic stimulation treatments the bsu has a

climatology of lake effect snowstorms of the great salt lake abstract characteristics of lake effect snowstorms associated with the great salt lake are described using wsr 88d radar imagery 16 well defined and 18 marginal lake effect events were identified from september 1994 through may 1998 excluding june august with the former used for more detailed analysis precipitation during the well defined events was frequently characterized by the irregular development of radar echoes over and downstream of the great salt lake the most commonly observed precipitation structures were solitary wind parallel bands that developed along or near the major axis of the gsl and broad area precipitation shields with embedded convective elements that formed near the southern shoreline regional scale composite analyses and rawinsonde derived statistics showed that the lake effect events occurred in post frontal westerly to northerly 700 hpa flow following the passage of an upper level trough and associated low level cold front the lake effect environment was characterized by

lithofacies and fluvial lacustrine environments of the palaeogene sevkhuul and ergil members ergiliin zoo formation south gobi mongolia the clastic sequence of the ergiliin zoo formation stretches along the mongolian chinese border in the southern gobi desert mongolia its members sevkhuul ergil exposed in the erdene sum region are well known for their vertebrate remains of late eocene and oligocene age based upon field work the continental red beds were subdivided into four units described as i prodelta mud sand flat ii delta front iii delta plain and iv calcretes all sub environments are in a fluvial lacustrine setting electronmicroprobe analysis in addition to conventional thin section examination was applied to shed some light on the complex mineral association made up of light minerals quartz plagioclase ternary feldspar orthoclase smectite illite rare palygorskite heavy minerals almandine pyrope solid solution series zoisite epidote s s s and abundant goethite and carbonate minerals calcite dolomite igneous rocks being exposed in the source area have contributed to the formation of carbonate minerals and mg bearing sheet silicates during diagenesis higher up on the delta plain transitional between distal alluvial and deltaic deposits fluids emerged from the distal alluvial fluvial deposits and formed calcareous duricrusts drawing conclusions from the rock colour the mineral assemblage and the palaeoecological data the climatic conditions may be described as alternating wet and dry seasons closely resembling those conditions of a modern savannah

geothermal exploration of paleozoic formations in central alberta this study explores the distribution of paleozoic formations in the central alberta basin and investigates rock properties with regard to their usability as geothermal reservoirs the study area of this regional scale investigation is about 160 km 200 km in size and located around edmonton where the basin depth ranges between 1 8 and 3 5 km a three dimensional 3d geological model was developed based on stratigraphic tops from about 7000 wells from the database of the alberta geological survey ags spatial distribution and thickness of deep formations were established in the 3d geological model porosity and permeability of four devonian carbonate formations cooking lake leduc and nisku formations and wabamun group were investigated using data from more than 50 000 core analyses average porosity of the devonian strata in the study area ranges from 4 5 nisku to 8 7 wabamun average permeability is between 3 5 10 15 m2 wabamun and 26 10 15 m2 leduc the distribution of both param

description and numerical model of pleistocene iceberg scours and ice keel turbated facies at toronto canada near toronto in southern ontario canada glaciolacustrine muds and shoreface sands of late pleistocene age early wisconsin glaciation 45 ka were deformed by icebergs ploughing the floor of an ancestral ice dammed lake ontario outcrop mapping and a ground penetrating radar survey identify ice scour structures up to 4 m deep up to 10 m wide and at least several hundred metres long with high standing lateral margins berms ploughing of lake floor sediment is also recorded by ice keel turbated facies in which storm deposited shoreface sands have been mechanically mixed with underlying muds palaeoenvironmental information for one prominent scour such as water depths estimates of the mass and draft of the ice mass and scouring forces can be determined using a simple finite element numerical model a mass of 0 04 million tonnes a keel draft of between 10 and 30 m and a scouring force of 5 103 kn is consistent with scouring by a small iceberg bergy bit or pressure ridged lake ice the former is preferred because of the considerable depth of the scour and the overall glacial depositional setting estimates of ice mass dimensions agree with independent reconstructions of palaeobathymetry no greater than 20 m derived from storm deposited hummocky and swaley cross stratified facies that fill the scour data presented here aid the identification of ice scour structures and turbated sediment in the ancient record despite being a common process on modern high latitude shelves descriptions of ancient structures and facies are few

reconstructed ice flow patterns and ice limits using drift pebble lithology outer nachvak fiord northern labrador discussion on the basis of their analysis of pebble lithologies and age estimates of marine shells the authors presented an interpretation for late quaternary events in outer nachvak fiord that they sav is incom atible with the late wisconsinan ice model of f k k and osh josenhans et al 1986 clark 1988 we believe that much of their data when reinterpreted do not conflict with our reconstruction and in fact can be accommodated by our reconstruction in contrast our data from nachvak fiord and the adjacent continental shelf are not compatible with their hypotheses nor have they directly addressed these data in their hypotheses in this discussion we will evaluate the clast morphologic and chronologic data used by the authors to develop their hypotheses we also summarize our work related to the glacial history of nachvak fiord and the adjacent shelf for the purpose of discussion and comparison with their hypotheses

high resolution seismo stratigraphy and sedimentological properties of late and postglacial sediments in lac guillaume delisle estuary and nastapoka sound eastern hudson bay lac guillaume delisle estuary and nastapoka sound are two sedimentary basins that recorded the late quaternary deglaciation on the eastern coast of hudson bay acoustic profiles reveal an average sediments thickness of 15 m in the estuary and 6 m in the sound these sediments reach 70 m thick in deep glacial troughs within the studied basins four seismo stratigraphic units overlying the acoustic basement were recognized unit 1 subaqueous ice contact and draped glaciomarine deposits associated with the quebec labrador ice sector qlis of the laurentide ice sheet lis and the tyrrell sea records the presence of a short ice marginal stillstand during glacial retreat unit 2 paraglacial and postglacial fluvial deltaic deposits and unit 3 postglacial silty deposits result from erosion of emerged sediments and redeposition in response to changes in relative sea level rsl finally unit 4 is composed of deformed deposits associated with a mass wasting event the stratigraphic sequence and the spatia

mid and late holocene sea level changes in roudsea marsh northwest england a diatom biostratigraphical investigation diatoms vascular vegetation sediment data and water salinity from contemporary intertidal environ ments in roudsea marsh northwest england are used to define altitudinal relationships between diatom assem blages and reference water levels comparison of these data with the high resolution diatom biostratigraphy of a fossil marsh sequence allows identification of fluctuations of relative sea level in the mid and late holo cene two oscillations in relative sea level are recorded a rise in sea level 0 6 m led to the inundation of the site after 6000 bp and was followed by a fall in sea level c 1 m around 4700 bp a second rise in sea level 0 5 m occurred before 2420 bp and was followed by a relatively stable or smaller rise of sea level during the last millennium the use of diatom groups based on marsh altitude was successful

numerical study of the influence of environmental conditions on lake effect snowstorms over lake michigan abstract numerical simulations are used to examine the influence of environmental parameters on the morphology of lake effect snowstorms over lake michigan a series of model sensitivity studies are performed using the colorado state university mesoscale model to examine the effects of lake land temperature difference surface roughness atmospheric boundary layer stability humidity and wind speed and direction on the morphology of simulated storms four morphological types of lake effect snowstorms have been identified i broad area coverage which may become organized into wind parallel bands or cellular convection ii shoreline bands with a line of convection roughly parallel to the lee shore and a well developed land breeze on the lee shore iii midlake band with low level convergence centered over the lake and iv mesoscale vortices with a well developed cyclonic flow pattern in the boundary layer the model is able to reproduce all four morphological types simulations varying environmenta

shelf erosion and glacial ice proximity in the labrador sea during and after heinrich events h 3 or 4 to h 0 as shown by foraminifera

the role of cloud top generating cells and boundary layer circulations in the finescale radar structure of a winter cyclone over the great lakes abstractdata from airborne w band radar are used in conjunction with thermodynamic fields from the weather research and forecasting model and air parcel back trajectories from the hysplit model to investigate the finescale reflectivity vertical motion and airmass structure of the comma head of a winter cyclone in the vicinity of the great lakes cloud top generating cells formed along an upper level frontal boundary vertically separating dry air which 48 h earlier was located in the upper troposphere over south central canada from moist air which was located in the lower troposphere over the southeast united states the stronger updrafts within the generating cells had vertical velocities ranging from 1 to 3 m s 1 the generating cells were important to precipitation production within the comma head precipitation trails formed within the generating cells could sometimes be followed to the boundary layer before merging boundary layer air beneath the cyclone s comma head exhibited convective circulati

the holocene evolution of permafrost near the tree line on the eastern coast of hudson bay northern quebec permafrost evolution in postglacial marine silts near the tree line was reconstructed using landform analysis 14c dating and palynostratigraphic analysis of peat sections in the forest tundra below the tree line four sites in peat plateaus have a stratigraphic sequence indicating an alluvial plain environment from 6000 to 4800 bp followed by a wetland supporting trees and shrubs with deep snow accumulation and without permafrost ground heave occurred between 1900 and 1200 bp as peat plateaus and palsas were formed in the shrub tundra above the tree line three permafrost sites with buried peat beds suggest that climatic conditions were cold enough for discontinuous permafrost in the surrounding landscape starting from land emergence about 5800 bp however fen expansion and sedge peat accumulation continued over unfrozen ground until 2300 1560 and 1400 bp at these dates the sites were buried with silt probably as a result of mass wasting on nearby permafrost mounds and then permafrost aggrad

a statistical analysis of bottom hole temperature data in southern alberta when bottom hole temperatures bht are plotted as functions of depth for different areas the plots exhibit differences in the spread of the data the regional variations in spread in southern alberta were mapped in detail on the basis of 33 653 bht data from 18 711 wells there are local areas with anomalously high spread values and the spread generally increases westward toward the disturbed belt also the spread values for data below the paleozoic erosional surface are greater than those above greater spread in the data appears to be associated with the occurrence of faults steeply dipping strata of different thermal conductivity and rough topography the increased spread associated with faults and steeply dipping strata is probably due to water movement this suggests that bottom hole temperatures may provide information about subsurface structure and phenomena as well as information on temperature

slip tendency analysis fault reactivation potential and induced seismicity in a deep geothermal reservoir abstract a slip tendency analysis is used to assess the reactivation potential of shear and dilational fractures in a deep geothermal reservoir in the northeast german basin based on the notion that slip on faults is controlled by the ratio of shear to normal stress acting on the plane of weakness in the in situ stress field the reservoir rocks composed of lower permian sandstones and volcanics were stimulated by hydraulic fracturing a surprisingly low microseismic activity was recorded with moment magnitudes mw ranging from 1 0 to 1 8 the slip tendency analysis suggests a critically stressed reservoir exists in the sandstones whereas the volcanic rocks are less stressed rock failure first occurs with an additional pore pressure of 20 mpa presumed failure planes form a conjugate set and strike nw and ne slip failure is more likely than tensional failure in the volcanic rocks because high normal stresses prevent tensional failure these results from slip tendency analysis are supported by the spatial distribution of recorded microseismicity source characteristics indicate slip rather than extension along presumed ne striking failure planes this suggests that slip tendency analysis is an appropriate method that can be used to understand reservoir behavior under modified stress conditions

mesoscale stratocumulus bands caused by gulf stream meanders abstract examination of visible and infrared imagery from geosynchronous and polar orbiter satellites reveals the occasional existence of mesoscale cloud bands of unusual width and area originating over the open northwest atlantic ocean during cold air outbreaks this phenomenon is of both dynamic and synoptic interest as a dynamic phenomenon it represents a mesoscale flow that is driven by transient surface features which are meanders in the gulf stream the forcing geometry and the resulting cloud pattern are similar in many respects to the anomalous cloud lines observed downwind of chesapeake and delaware bays in similar conditions these open ocean cloud bands are often of a larger scale however because the gulf stream meanders represent the largest scale high amplitude coastal features in the western north atlantic these cloud bands are of synoptic interest because when present they play a major role in determining the cloud pattern over much of this oceanic region examination of surface

climatological characteristics and orographic enhancement of lake effect precipitation east of lake ontario and over the tug hill plateau abstractlake effect snowstorms east of lake ontario are frequently intense and contribute to substantial seasonal accumulations especially over the tug hill plateau hereafter tug hill which rises at a gentle 1 25 slope to 500 m above lake level using a variety of datasets including radar imagery from the ktyx fort drum new york wsr 88d this paper examines the characteristics of lake effect precipitation east of lake ontario over 13 cool seasons 16 september 2001 15 may 2014 during this period days with at least 2 h of lake effect account for 61 76 of the mean cool season snowfall and 24 37 of the mean cool season liquid precipitation mean monthly lake effect frequency and snowfall peak in december and january the highest lake effect frequency and snowfall occur over the western and upper tug hill with an arm of relatively high lake effect frequency and snowfall extending to the southeast shore of lake ontario to the east lee lake effect frequency and snowfall decrease abruptly ov

a cloud line over the gulf stream 1 a 1000 km long cloud line over the major axis of the gulf stream was detected in imagery from a number of satellites on april 24 2001 analysis of environmental conditions shows that such a cloud line is formed when the synoptic low level wind is parallel to the gulf stream axis and the sky is clear conditions that rarely occur in the high temperature and high moisture gulf stream region the psu ncar fifth generation mesoscale model mm5 is used to study the cloud line results show that upward motion of the air in the middle of the gulf stream caused by mesoscale solenoidal circulation induced by the large surface thermal gradient is the source for the large cloud line formation this cloud line formation mechanism is different from that of commonly observed ship cloud lines induced by ship stack emissions and its extent is much longer than that of cloud lines induced by lake effects

late glacial ice margins and deglacial chronology for southeastern baffin island and hudson strait eastern canadian arctic radiocarbon dates from marine piston cores and from onshore raised marine stratigraphic sections in the hudson strait region were used to reconstruct deglacial isochrons for 9900 9500 8800 8500 and 8000 bp at the culmination of the gold cove readvance 9900 bp labrador ungava ice flowed northeastward across hudson strait and outer frobisher bay and stood for the last time on the baffin island continental shelf subsequent retreat by calving was rapid and profound opening the entire hudson strait marine trough by 9500 bp at this time ice dispersal from foxe basin labrador ungava and local ice on meta incognita peninsula supported tidewater margins along much of the coastline with the exception of northernmost ungava peninsula where the ice margin stabilized onshore this onshore margin remained in place throughout the cockburn substage while a major northeastward readvance of ungava bay ice the noble inlet readvance from 8800 to 8500 bp crossed outer hudson strait grounding on the hudson st

shear instability wave along a snowband instability structure evolution and energetics derived from dual doppler radar data abstract this article presents a detailed analysis of a meso scale 17 km wavelength shear instability wave along a snowband using a series of dual doppler radar data the wave developed along a low level shear line that formed under the strain wind field caused by an adjacent mesoscale vortex the horizontal wind shear across the line was largest at lower levels and the eddy component horizontal winds and the retrieved pressure anomaly showed a bottom intensified structure as well the resultant vertical pressure gradient force was found to be responsible for the enhancement of alternating updrafts and downdrafts that were subsequently related to the formation of the reflectivity core gap structure of the wave eddy kinetic energy eke budgets of the evolving disturbance were investigated using time series of retrieved kinematic and thermodynamic data the wave grew at an approximately constant growth rate for about 40 min from its onset the eke in this quasi linear growth period was primarily gen

orographic influences on a great salt lake effect snowstorm abstractalthough several mountain ranges surround the great salt lake gsl of northern utah the extent to which orography modifies gsl effect precipitation remains largely unknown here the authors use observational and numerical modeling approaches to examine the influence of orography on the gsl effect snowstorm of 27 october 2010 which generated 6 10 mm of precipitation snow water equivalent in the salt lake valley and up to 30 cm of snow in the wasatch mountains the authors find that the primary orographic influences on the event are 1 foehnlike flow over the upstream orography that warms and dries the incipient low level air mass and reduces precipitation coverage and intensity 2 orographically forced convergence that extends downstream from the upstream orography is enhanced by blocking windward of the promontory mountains and affects the structure and evolution of the lake effect precipitation band and 3 blocking by the wasatch and oquirrh mountains which funnels the flow into the sal

morphology and facies architecture of a falling sea level strandplain umiujaq hudson bay canada coastal strandplain deposits near umiujaq eastern hudson bay canada were formed under falling relative sea level conditions resulting from postglacial isostatic uplift ground probing radar profiles across the strandplain reveal a lower progradational unit lpu discordantly overlain by an upper progradational unit upu which were correlated with stratigraphic sections exposed in incised valley walls the discordance is a wave erosion surface wes that separates fine shoreface sands of the lpu from coarse sand and gravel of the upu major basal downlap surfaces can be traced updip into marine terraces and define downstepping wedges the downstepping is interpreted as representing autocyclic morphological reconfiguration rather than a response to changes in the rate of sea level fall the internal architecture is strongly dependent on the accommodation and thus on antecedent topography a conceptual model for strandplain deposition under falling sea level incorporates a bipartite shallowing upward sandy succession when sufficient accommodation is available where accommodation space is limited a sharp based bar and beach sandbody directly overlies muddy deeper water deposits and the wes resembles a regressive surface of erosion

holocene deltaic sedimentation along an emerging coast nastapoka river delta eastern hudson bay quebec eastern hudson bay is characterized by falling relative sea level as a result of post glacial isostatic rebound which makes the region a natural laboratory for rapid forced regression where the evolution of deltaic systems and offshore sedimentation patterns can be studied a multidisciplinary approach involving airphoto analysis offshore geophysical surveys sediment coring and facies and diatom analyses was used in this study of the nastapoka river delta the delta has formed as a result of the fluvial erosion of emerged quaternary sediments but is mainly subaqueous offshore in the prodelta zone the oldest deposits are glaciomarine laid down when the ice front of the receding laurentide ice sheet stood on the nastapoka hills some 7700 6800 years bp lateral equivalents of this glaciomarine unit are presently exposed on land the shallow water platform of the delta shows a thin surficial unit of wave worked sand that overlies fine grained deeper water deposits derived from erosion of clay soils

model simulations examining the relationship of lake effect morphology to lake shape wind direction and wind speed abstract idealized model simulations with an isolated elliptical lake and prescribed winter lake effect environmental conditions were used to examine the influences of lake shape wind speed and wind direction on the mesoscale morphology this study presents the first systematic examination of variations in lake shape and the interplay between these three parameters the array of 21 model simulations produced cases containing each of the three classic lake effect morphologies i e vortices shoreline bands and widespread coverage and in some instances the mesoscale circulations were composed of coexisting morphologies located over the lake near the downwind shoreline or inland from the downwind shore as with lake effect circulations simulated over circular lakes the ratio of wind speed u to maximum fetch distance l was found to be a valuable parameter for determining the morphology of a lake effect circulation when variations of lake shape wind speed and wind direction were introduced f

comparison of observations with idealized model results for a method to resolve winter lake effect mesoscale morphology abstract forecasters in the great lakes region have for several decades recognized a general relationship of wind speed and overlake fetch to lake effect snowstorm morphology a recent study using idealized mesoscale model simulations of lake effect conditions over circular and elliptical lakes showed the ratio of wind speed to maximum fetch distance u l may be used to effectively predict lake effect snowstorm morphology the current investigation provides an assessment of the u l criteria using observational datasets previously published great lakes lake effect snowstorm observational studies were used to identify events of known mesoscale morphology hindcasts of nearly 640 lake effect events were performed using historical observations with u l as the predictor results show that the quantity u l contains important information on the different mesoscale lake effect morphologies however it provides only a limited benefit when being used to predict mesoscale morphology in real lake effect situations

towards a sediment and organic carbon budget for hudson bay abstract a preliminary sediment and organic carbon budget is constructed for the hudson bay marine system based on published literature and new data collected from nine rivers and 13 sediment boxcores the budget considers the main inputs of terrestrial and marine components of sediment and organic carbon and the main sinks sediment burial and losses oxidation export to hudson strait sedimentation rates 0 032 0 23 g cm 2 yr 1 were estimated from 210 pb profiles and a sediment advection diffusion model in our cores and in two cores collected previously by lockhart et al lockhart w l et al 1998 fluxes of mercury to lake sediments in central and northern canada inferred from dated sediment cores biogeochemistry 40 163 173 sedimentation rates implied by the 210 pb profiles were verified against profiles of 137 cs and for some of the cores contaminant pb the sediment sink in hudson bay was estimated at 138 64 10 6 t a 1 by applying the average sedimentation rate to the area of active sedimentation in the bay 15 of the seafloor calculated according to a regional sedimentation map developed from seismic data josenhans h w et al 1988 preliminary seismostratigraphic and geomorphic interpretations of the quaternary sediments of hudson bay natural resources canada the known sediment sources to hudson bay include river input 11 6 6 10 6 t a 1 subaerial coastal erosion 8 4 10 6 t a 1 marine primary production 24 2 17 10 6 t a 1 and atmospheric deposition 0 5 10 6 t a 1 based on the available data the modern sediment input 44 3 18 10 6 t a 1 represents only about one third of the apparent sediment sink in hudson bay resuspension and lateral transport of shallow water deposits primarily glacigenic and winnowing from topographic highs likely consequences of the exceptional continuous relative sea level rsl fall in hudson bay provides a plausible source for the 116 10 6 t a 1 imbalance using organic carbon and 13 c values in the cores we estimate the burial of particulate organic carbon poc in sediments at 1 3 0 6 10 6 t c a 1 of which 80 is marine the importance of reworked glaciomarine carbon to the burial flux is difficult to estimate because modern autochthonous primary production provides a large source of poc to the system 16 1 7 10 6 t c a 1 and its degradation is not well constrained the 0 58 10 6 t c a 1 terrestrial carbon estimated to be transported as part of the redistributed sediment load accounts for almost one half the total terrigenous poc inputs to the bay if sediment and oc supply and burial in the hudson bay system are presently responding to the history of isostatic rebound as proposed here the task of predicting and measuring the additional consequences of river diversions and climate change e g sea ice permafrost runoff is rendered considerably more difficult

facies related diagenetic alteration in lacustrine deltaic red beds of the paleogene ergeliin zoo formation erdene sum area s gobi mongolia the late eocene ergeliin zoo formation mongolia was subdivided into four facies associations stratigraphic units which are characterized by various carbonate minerals 1 mud sand flat low fe dolomite high mg calcite 11 delta front high mn dolomite low mg calcite 111 delta plain high mn calcite low mg and moderate fe calcite iv calcretes high mg calcite besides carbonate minerals prevailing among the cement minerals some sheet silicates ca smectite palygorskite illite apatite and fe oxide hydroxides occur in the siliciclastics of these lacustrine deltaic red beds the prodelta mud sand flat deposits unit 1 were dolomitized and cemented by high mg calcite during evaporative pumping at times of low lake stand under redox conditions greater than 0 and intrastratal solutions of strong alkalinity manganoan dolomite is fairly widespread in the delta front sediments unit 11 the mn content of which is likely to have been derived from decomposition of vertebrate remains the mn fe ratio in the carbonate minerals was controlled by the redox conditions and the shallow burial depth in the porous delta front sediments eh values around zero and ph values slightly above 7 occurred as a result of basinward fluid movements high mn dolomite high fe dolomite low mg calcite fluid movement was locally impeded by finer grained delta plain deposits unit iii intertonguing with arenaceous aquifers low mg moderate fe calcite high mn calcite higher up on the delta plain with deposits laid down in an environment transitional between distal alluvial and deltaic unit iv closed lake basin conditions reappeared as fluids emerged from the distal alluvial fluvial deposits or were driven by capillary force to ascend and form calcretes abundant in mg bearing calcite the climatic conditions in the erdene sum area mongolia are likely to have been semi and transitional into arid c 2005 elsevier b v all rights reserved

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

convective evolution across lake michigan during a widespread lake effect snow event abstract lake effect snowstorms generally develop within convective boundary layers which are induced when cold air flows over relatively warm lakes in fall and winter mesoscale circulations within the boundary layers largely control which communities near the downwind shores of the lakes receive the most intense snow the lack of quantitative observations over the lakes during lake effect storms limits the ability to fully understand and predict these mesoscale circulations this study provides the first observations of the concurrent spatial and temporal evolution of the thermodynamic and microphysical boundary layer structure and mesoscale convective patterns across lake michigan during an intense lake effect event observations analyzed in this study were taken during the lake induced convection experiment lake ice aircraft and sounding observations indicate that the lake effect snows of 13 january 1998 developed within a convective boundary layer that grew rapidly across lake michigan boundary

the evolution of lake effect convection during landfall and orographic uplift as observed by profiling radars abstracta pronounced snowfall maximum occurs about 30 km downwind of lake ontario over the 600 m high tug hill plateau hereafter tug hill a region where lake effect convection is affected by mesoscale forcing associated with landfall and orographic uplift profiling radar data from the ontario winter lake effect systems field campaign are used to characterize the inland evolution of lake effect convection that produces the tug hill snowfall maximum four k band profiling micro rain radars mrrs were aligned in a transect from the ontario coast onto tug hill additional observations were provided by an x band profiling radar xpr analysis is presented of a major lake effect storm that produced 6 4 cm liquid precipitation equivalent lpe snowfall over tug hill this event exhibited strong inland enhancement with lpe increasing by a factor of 1 9 over 15 km horizontal distance mrr profiles reveal that this enhancement was not due to increases in the depth or intensity of lake effect convection with

lake aggregate mesoscale disturbances part iii description of a mesoscale aggregate vortex abstract the structure of a meso scale vortex that developed over the great lakes in late autumn is described understanding the structure of this particular vortex is important because 1 it altered local and regional scale precipitation 2 it developed in a complicated fashion and 3 it represents a class of vortices that develop frequently during cold air outbreaks over the great lakes and whose development is not yet understood detailed perturbation analyses of the synoptic scale and mesoscale conditions over the great lakes that led to the vortex development are presented using model output from previous numerical simulations that included all of the great lakes wl and none of the great lakes nl the initial thermal perturbation was characterized by an elongated warm plume near the surface that advanced southeastward toward the mid atlantic coast as cold air overspread the entire lakes region the plume then became more circular and deepened as it rotated toward the northeast in response to

the nastapoka drift belt eastern hudson bay implications of a stillstand of the quebec labrador ice margin in the tyrrell sea at 8 ka bp during deglaciation of eastern hudson bay the western margin of the quebec labrador sector of the laurentide ice sheet came to a stillstand about 8 14c ka bp along the nastapoka hills a series of topographic highs along the bay these hills are the northward continuation of the eastern hudson bay cuesta system it left a drift belt consisting of ice contact submarine fans along the western slopes of the hills small frontal moraines on hilltops and grounding line deposits on sills between the hills geomorphological sedimentary and radiometric evidence suggest that the stillstand responsible for deposition of the nastapoka drift belt was either entirely or partly synchronous with the deposition of the sakami moraine farther south there was a period when these two morainic systems marked a continuous ice margin these stillstands occurred due to reduction of ablation at the ice margin in the nastapoka hills ablation slowed down when the ice margin was anchored on higher relief and stood at a region

evolution of fracture and fault controlled fluid pathways in carbonates of the albanides fold thrust belt the process of fracture and fault formation in carbonates of the albanides fold thrust belt has been systematically documented using hierarchical development of structural elements from hand sample outcrop and geologic map scales the function of fractures and faults in fluid migration was elucidated using calcite cement and bitumen in these structures as a paleoflow indicator two prefolding pressure solution and vein assemblages were identified an overburden assemblage and a remote tectonic stress assemblage sheared layer parallel pressure solution surfaces of the overburden assemblage define mechanical layers shearing of mechanical layers associated with folding resulted in the formation of a series of folding assemblage fractures at different orientations depending on the slip direction of individual mechanical layers prefolding and folding related fracture assemblages together formed fragmentation zones in mechanical layers and are the sites of incipient fault localization further deformation along these sites was accommodated by rotation and translation of fragmented rock which formed breccia and facilitated fault offset across multiple mechanical layers strike slip faults formed by this process are organized in two sets in an apparent conjugate pattern calcite cement and bitumen that accumulated along fractures and faults are evidence of localized fluid flow along fault zones by systematic identification of fractures and faults their evolution and their fluid and bitumen contents along with subsurface core and well log data we identify northeast southwest trending strike slip faults and the associated structures as dominant fluid pathways in the albanides fold thrust belt

regional trends in radiogenic heat generation in the precambrian basement of the western canadian basin radiogenic heat generation values for 381 basement samples from 229 sites in the western canadian basin exhibit a lognormal frequency distribution the mean value