ostracodes and paleoenvironments of the late quaternary don and scarborough formations toronto ontario type section exposures at the don valley brickyard and scarborough bluffs were studied for ostracode occurrences in all 12 species were identified from the don formation with candona rawsoni and

successions of invertebrate microfossils and the late quaternary deglaciation of the central st lawrence lowland canada and united states abstract foraminiferal and ostracode assemblages in late glacial and early post glacial sediments of the central st lawrence lowland show that a proglacial lake glacial lake st lawrence preceded the champlain sea in some parts of the lowland and that the champlain sea was in contact with the laurentide ice sheet during deglaciation of other parts of the lowland glaciolacustrine and glaciomarine environments were followed by marine environments with salinity as high as 24 34 the higher salinity water in the champlain sea was part of a salt water wedge extending from the gulf of st lawrence into the central st lawrence lowland the beginning of the champlain sea is placed between 11 4 and 11 6 ka bp on the basis of radiocarbon ages for the arrival of the salt water wedge in the central st lawrence lowland the distribution of rhythmites associated with glacial lake st lawrence shows that subaqueous outwash fans in the ottawa area were deposited in glacial lake st lawrence rather than in the champlain sea

reconstruction of wisconsinan age ice dynamics and compositions of southern ontario glacial diamictons glaciofluvial lacustrine and deltaic sediment abstract macrofabric analysis of till sections in south central ontario confirms that clast orientation yields information related to changing ice dynamics during the wisconsinan glaciation test stations in six sections yield unimodal to multimodal macrofabrics that indicate ice flow direction ranging from se nw vectors when ice was thin and flowing radially to variable ne sw nne ssw and n s vectors when ice thickened ice loci appear to range from the lake ontario basin and southern quebec thin ice labrador ungava thicker ice and hudson bay thickest ice the north south fabric may identify the intergrowth of keewatin labrador ice presumably the maximum ice thickness of the last glacial maximum lgm the preliminary data support the theory that topography directed ice movement during preliminary and closing stages of glaciation in southern ontario while thick ice generated flow vectors largely unaffected by underlying topography hence leading to clast azimuthal variations reflecting changing ice loci with glacier growth the fabrics analyzed suggest that inferring difference between ductile and brittle lodgement tills is possible as well as to identifying possible glacial tectonic action overburden loading that disturbs the least friction fit position of clasts in till the changing dynamics within till sheets are supported in part by variations in glacial crushing seen in sem imagery that depict a range of microtextures from full scale fractures under brittle conditions to those indicating less viscous transport under ductile regimes to some degree changes in flow direction are further supported by geochemical variations that relate to bedrock regolith up glacier controlling ca dilution and variable concentrations of rare earth elements rees

sedimentation in a large lake a reinterpretation of the late pleistocene stratigraphy at scarborough bluffs ontario canada a lithofacies code developed for diamicts emphasizes facies variability in the classic upper pleistocene glaciogenic sequence at scarborough bluffs ontario canada lithological breaks along the bluffs are traditionally assigned to incursions of grounded ice margins and to interstadial lakes formed during ice retreat during the early and middle wisconsin detailed sedimentological logging through three diamict units previously formalized as sunnybrook seminary and meadowcliffe tills and intervening sandy lithofacies shows absence of glaciotectonic structures and diamicts associated with grounded glacier ice traction current activity during diamict accumulation postdepositional resedimentation of diamicts into topographic lows accompanied by turbidite activity a subaqueous deltaic origin for intervening sandy lithofacies and loaded transitional and interbedded contacts between sand and diamict the scarborough bluffs sequence may be the preserved bottom stratigraphy of a large lake the bottom stratigraphy results from repeated basinward progradation of deltaic sandy lithofacies over glaciolacustrine diamicts deposited below floating ice whether ice shelf ramp bergs or lake ice a facies model is presented for glaciolacustrine diamict deposition on the floors of enlarged pleistocene lakes trapping substantial volumes of fine grained suspended sediment

seasonal variation and instability nature of the north pacific subtropical countercurrent and the hawaiian lee countercurrent 1 the relation between baroclinic instability of the north pacific subtropical countercurrent stcc and the hawaiian lee countercurrent hlcc and seasonal evolution of mesoscale sea surface height ssh variability was investigated by using historical hydrographic data and altimeter derived ssh anomaly data during 1992 2000 the annual and monthly mean dynamic height climatologies show two robust eastward flowing countercurrents the stcc extends typically along 24 n from 130 e to 160 w and slightly shifts to the north as it flows toward the east and the hlcc is located typically along 20 n and extends from about 150 e to just west of the hawaiian islands seasonal variations of the stcc in the western north pacific and the hlcc west of the hawaiian island where the eddy variability is relatively larger than the background were quite different the stcc hlcc is strong in winter summer to summer winter and weak in fall spring in contrast seasonal evolution of mesoscale ssh variability has almost the same cycle in the two countercurrent regions the eddy kinetic energy eke is a maximum in spring and a minimum in fall the dominant zonal scales are shortest in late winter and become longer with time a linear quasigeostrophic stability analysis using a three layer model indicates that instability properties are very similar between the two countercurrent regions the stcc and the hlcc become baroclinically more unstable during winter and late fall to winter respectively due to strong vertical velocity shear and weak stratification between the stcc hlcc and underlying westward flow and the most unstable wave during this season has an e folding timescale of about 2 3 months and a zonal wavelength of about 300 400 km the same behavior of the seasonal evolution of the mesoscale variability in the two countercurrent regions is a manifestation of these similarities in terms of increasing nonlinearity of the unstable waves and an inverse cascade of the eddy energy we discussed generation processes of the mesoscale ssh disturbances

the circulation south of australia derived from an inverse model an inverse model is used to determine circulation and volume transports in the australian sector of the southern indian ocean from observations during woce water movement in the upper 1000 m is westward along the continental slope and eastward in the subantarctic front saf the subtropical front is not associated with continuous eastward flow however such flow appears to build up between 120 e and 132 e where it dominates the region between 37 s and 42 s antarctic intermediate water is found to move from the pacific into the indian ocean except in the region of the saf where it moves from the indian to the pacific ocean circumpolar deep water exhibits weak flow which can only be reliably resolved in the upper part where it is predominantly westward antarctic bottom water enters the australian basin through two depressions in the australian antarctic discordance at 125 37 e and at 126 30 e

effects of velocity shear in advective mixed layer models abstract a general multidimensional model of the upper mixed layer of oceans and lakes is presented the density profile is approximated as uniform over the depth of the layer such an assumption is not made for the distribution of the horizontal velocity component as there is no observational evidence for it in fact many observations indicate that important velocity shears exist in regions where advection can be expected to play an important role in the dynamics of the mixed layer such as lakes near upwelling and frontal areas and in equatorial oceanic regions it is shown that vertical shear in the horizontal velocity field combined with a horizontal density gradient can result in the production or absorption of mechanical energy production results if the velocity shear tends to destabilize the density profile consumption if the tendency is stabilizing so that work against gravity must be done to mix the stabler density profile to uniformity in the mechanical energy equation this effect of th

on the variability of southern ocean front locations between southern brazil and the antarctic peninsula a 4 year expendable bathythermograph data set 1984 1987 from the area between southern brazil and the antarctic peninsula provides information on the interannual variability of front locations two boundaries of subtropical water at different depths are identified north and south of the brazil current falkland malvinas current confluence zone the northern subtropical front is displaced over a large part of the argentine basin from one observational period to the other the shallow southern subtropical front appears fixed to the falkland escarpment the polar front and subantarctic front locations do not vary much except for one case where a cold core eddy in the polar frontal zone causes a large northward displacement of the subantarctic front

double celled subtropical gyre in the south atlantic ocean means trends and interannual changes 1 we present here a study of the mean upper layer structure of the south atlantic subtropical gyre sasg and its modes of variability based on archiving validation and interpretation of satellite oceanographic data sea level anomaly data gravity recovery and climate experiment based mean dynamic topography mdt models reynolds sea surface temperatures and two tide gauge time series from permanent service for mean sea level analysis of the mdts shows that the sasg mean structure is represented by a double cell circulation the southern cell being a narrow quasi zonal strip centered around 33 s its southern limb is limited by the recently discovered saint helena current tristan da cunha current sthc tcc and the north subtropical front around 35 s this system is shown to be well separated from the south atlantic current south subtropical front around 42 45 s a method based on singular spectrum analysis was used to determine the principal modes of variability through the decomposition of the data into band passed data sets the altimeter sea level trend analysis suggests that the sasg pattern is slowly migrating southward and has been growing in amplitude between 1994 and 2006 with local growth rates of 5 10 mm yr occurring in the southern cell flow intensifications in this period 2 3 cm s in the south equatorial current and north brazil undercurrent 3 5 cm s in the benguela current and weakening by 4 5 cm s in the sthc tcc are recorded the altimeter derived sea level trend is coherent with the growing phase of a bidecadal oscillation found from both tide gauges

paleobiology of the sand beneath the valders diamicton at valders wisconsin abstract previously undescribed pollen plant macrofossils molluscs and ostracodes were recovered from a 2 5 m thick glaciolacustrine unit of silty sand and clay at valders wisconsin the interstadial sediment was deposited about 12 200 14 c yr b p after retreat of the green bay lobe that deposited diamicton of the horicon formation and before advance of the lake michigan lobe that deposited the red brown diamicton of the valders member of the kewaunee formation fluctuations of abundance of candona subtriangulata cytherissa lacustris and three other species define four ostracode biozones in the lower 1 7 m suggesting an open lake environment that oscillated in depth and proximity to glacial ice pollen is dominated by picea and artemisia but the low percentages of many other types of long distance origin suggest that the terrestrial vegetation was open and far from the forest border the upper part of the sediment a massive sand deposited in either a shallow pond or a sluggish stream contains a local concentration of plant macrofossils the interpretation of a cold open environment is supported by the plant macrofossils of more than 20 species dominated by those of open mineral soils arenaria rubella cerastium alpinum type silene acaulis sibbaldia procumbens dryas integrifolia vaccinium uliginosum var alpinum armeria maritima etc that in north america occur largely in the tundra and open tundra forest ecotone of northern canada ice wedge casts occur in the sand

glacial and periglacial erosion of the appalachians abstract the marine 18 o record indicates that the first ice advance into the appalachians equivalent to that of the late wisconsin occurred in the pliocene at about 2 4 ma only periodic localized glacial and periglacial activity occurred in the northern appalachians from 2 33 to 0 85 ma after 0 85 ma middle to late pleistocene eight out of ten glaciations covered the northern appalachians and brought periglacial conditions to the southern appalachians during the last 850 000 years glaciation extended to the late wisconsin limit within the appalachians for 15 of the time and extended to the early wisconsin limit just north of the appalachians for 25 of the time pleistocene glacial erosion of the appalachians of 120 200 m is necessary to account for the estimated volume of pleistocene ocean sediment derived from the appalachians and the estimated volume of pliocene pleistocene glaciogenic ocean sediment derived from the entire laurentide ice sheet this amount of glacial erosion occurring over the maximum expectable duration of pliocene pleistocene ice cover of 247 000 years yields glacial erosion rates from 0 5 0 8 m ka 1 such depths of erosion by thick warm based ice streams were localized in the lowlands and estuaries of the northern appalachians in the maritimes the presence of thin cold based ice caused minimal erosion of uplands periglacial landforms and tundra boreal forest were distributed throughout the appalachian highlands and the northern coastal plain during the glacial maxima periglacial erosion of 0 15 0 30 m ka 1 near the ice in pennsylvania decline to 0 1 0 2 m ka 1 in the southern piedmont each cold period almost completely renewed the regolith by eroding slopes and filling valleys the cumulative effect of the eight to ten major cold events could have produced as much as a few ten s of meters of periglacial ridge top lowering during the pleistocene both estimated glacial and periglacial erosion rates greatly exceed estimated current fluvial erosion rates therefore glacial and periglacial processes should be considered the dominant processes in shaping the present appalachian landscape the northern appalachians may be evolving towards a form where the landscape provides just the shape necessary to permit the least work conveyance of the ice across the region during glacial maxima the southern appalachians may be evolving towards a form where the landscape provides just the hillslope form necessary to transport the debris provided by periglacial conditions

soil grain and water chemistry in relation to human selenium responsive diseases in enshi district china selenium deficiency keshan disease and toxicity diseases in humans occur within 20 km of each other in enshi district in china and have been linked to environmental levels of se low concentrations of se are associated with jurassic siltstones and sandstones whereas high concentrations occur in areas underlain by permian carbonaceous strata although these broad relationships between se in the environment and the human population have been established previously not all villages underlain by the carbonaceous strata suffer se toxicity problems and the precise controls on se distribution and availability have not been quantified in the present study soil grain drinking water and human hair samples are examined to determine the controls on se availability in 3 se environments in enshi district five low se and keshan disease villages 5 high se and no toxicity villages and 5 high se and toxicity villages were selected for the study results show that the majority of samples in the low se villages are deficient or marginal in se and that se availability to plants is inhibited by adsorption onto organic matter and fe oxyhydroxides in soil therefore remediation strategies involving the application of se fertiliser direct to the soil may not increase plant se levels as expected in the high se villages localised lithological variations result in considerable ranges in se concentrations in all sample types deficient and excessive levels of se are recorded in samples from the same village selenium bioavailability in the high se toxicity villages is controlled by the total soil se concentration and ph a greater proportion of the se is plant available in villages where the carbonaceous strata are interbedded with limestone villagers should be advised to avoid planting crops in these areas if possible

the subtropical front satellite observations during fronts 80 satellite derived sea surface temperature in situ hydrography data and satellite tracked drifter data collected during winter 1979 1980 as part of the fronts 80 experiment are used to describe the spatial structure of the north pacific subtropical front northeast of hawaii the satellite observations reveal a deformation scale meander 85 km 32 km in association with the front having an evolution time scale of 60 days the satellite measurements of the change in sea surface temperature across the front are typically 1 c within a distance of 10 km the correlation coefficients between the satellite data and the in situ hydrographic data were computed and found to be significantly nonzero above 800 m the high correlation at deep levels indicates that the satellite was viewing a feature with sizable vertical extent not just a surface phenomenon additionally the hydrographic data and drifter trajectories were combined with the satellite derived sea surface temperature data together they demonstrate that the feature observed by the satellite was nearly stationary during the experiment period in addition they also indicate that the flow along the front was nearly in geostrophic balance

descriptive oceanography during the frontal air sea interaction experiment medium to large scale variability medium and large scale oceanographic variability in the sargasso sea is examined during the frontal air sea interaction experiment fasinex focusing primarily on processes that influence the formation of subtropical fronts from fall to spring the mean meridional gradient of meridional ekman transport in the subtropical convergence zone stcz enhances the meridional sea surface temperature ts gradients between 26 o and 32on in the presence of this enhanced mean gradient baroclinic eddies with zonal wavelengths of 800 km and periods of 200 days exert the dominant influence on the formation of subtropical fronts at medium and large scales these eddies generate westward propagating ts anomaly features with the same dominant wavelengths and periods they are confined between 26 o and 32on and have amplitudes that occasionally exceed ioc ts fronts tend to be found within bands 200 km wide that roughly follow the periphery of these anomaly features deformation in the horizontal eddy current field is primarily responsible for the existence of these frontal bands the migration of the strong front originally bracketed by the fasinex moored array was related to the westward propagation of the larger scale eddy anomaly frontal band pattern the moored array was located within a warm anomaly feature during most of the experiment which produced exceptionally warm conditions in the upper ocean these anomalies are confined between 26 o and 32on not only because the relatively large seasonal mean tsy there allows horizontal eddy currents to force strong anomalies but also because the baroclinic eddies with wavelengths of 800 km and periods of 200 days are confined to the stcz large meridional variability exists in many properties of the eddy field much of which can be traced to the influence of the sargasso sea mean current field on eddy variability

comments and reply on sedimentation in a large lake a reinterpretation of the late pleistocene stratigraphy at scarborough bluffs ontario canada comment

thermoluminescence dating studies of glacial silts from ontario to develop procedures for the direct dating of glacially related silts by thermoluminescence tl i have applied previously proposed techniques to three polymineralic 4 11 m samples from the toronto area furthermore one of these samples was studied in detail by isolating some mineral fractions the principal conclusion is that the tl of the lodgment halton till from woodbridge was not significantly reset during deposition whereas the tl of the waterlaid upper thorncliffe silt from the scarborough bluffs was reset as was the tl of the third sample wc st a massive silt from woodbridge that has been generally correlated with the glaciolacustrine sunnybrook diamict at the bluffs this conclusion follows from the observation of feldspar tl apparent ages of 140 ka for the 12 ka bp halton till and of 36 and 66 ka for the upper thorncliffe and wc st samples respectively the four laboratory factors that contributed most to inaccuracies in the tl apparent ages were 1 anomalous fading in the felds

mesoscale subduction at the antarctic polar front driven by baroclinic instability abstract a study of mesoscale subduction at the antarctic polar front pf is conducted by use of hydrographic data from a high resolution quasi synoptic survey of the front the geostrophic velocity and isopycnal potential vorticity pv fields are computed and the ageostrophic flow diagnosed from the semigeostrophic omega equation it is found that the ageostrophic circulation induced by baroclinic instability counteracts the frontogenesis and frontolysis effected by the confluence and difluence respectively of the geostrophic velocity field though the sense of the ageostrophic circulation is reversed repeatedly along the front the existence of pv gradients along isopycnals leads to a net cross front bolus transport in response to a reversal of this gradient with depth a necessary condition for the onset of baroclinic instability the bolus transport is northward at the protruding temperature minimum layer that characterizes the pf and southward above this net cross front overturning circul

the sedimentary record of drifting ice early wisconsin sunnybrook deposit in an ancestral ice dammed lake ontario canada abstract outcrops of pebbly mud diamict at scarborough in southern ontario canada the so called sunnybrook till are associated with the earliest incursion of the laurentide ice sheet lis into mid continent north america some 45 000 years ago the sunnybrook is a blanket like deposit containing deepwater ostracodes and occurs conformably within a thick 100 m succession of deltaic and glaciolacustrine facies that record water depth changes in a large proglacial lake contextual evidence associated facies sedimentary structures deposit geometry and landforms indicates a low energy depositional setting in an ice dammed ancestral lake ontario in which scouring by floating ice masses was an important process u shaped iceberg cut scours with lateral berms up to 7 m deep occur on the upper surface of the sunnybrook and are underlain by sub scour structures that extend several meters below the scour base ice rafted concentrations of clasts clast layers grooved surfaces formed by floating ice glissading over a muddy lake floor soft sediment striations and melanges of sand and mud mixed by grounding ice keels ice keel turbates are present and are all well known from modern cold environments the wider significance of this depositional model is that the lis margin lay east of scarborough and did not overrun southern ontario this finding is in agreement with recent data from the erie basin of canada ohio and indiana where deposits formerly correlated with the sunnybrook and thus implying an extensive early wisconsin ice sheet are now regarded as illinoian a speculative hypothesis is proposed that relates deposition of the sunnybrook and two younger deposits of similar sedimentology to surge like instabilities of the southern lis margin

hydrogen uptake and diffusion in callovo oxfordian clay rock for nuclear waste disposal technology abstract the callovo oxfordian clay rich rock formation is currently considered as host rock barrier in the french geological repository facility for radioactive waste meuse haute marne after the closure of the facility hydrogen gas is expected to develop mainly from anaerobic corrosion of steel containers and other iron containing structures gas pressure build up could impact the safety of the repository it is therefore important to acquire in depth knowledge on the interaction between hydrogen gas and surrounding clay rock in terms of uptake ability and diffusion hydrogen uptake capacity was evaluated on dried clay rock samples i at 20 k to allow for hydrogen liquefaction and determine the maximal h 2 uptake of the clay and ii at typical pressure and temperature conditions expected to develop in the repository up to 363 k and a hydrogen pressure of 40 60 bar h 2 absorption on the dried raw callovo oxfordian start to saturate at about 30 40 bar and the average adsorption above 40 bar is about 0 1 in weight quasi elastic neutron scattering spectroscopy was used to study the diffusion mechanism of hydrogen gas in the clay rock at the microscopic scale and to determine hydrogen self diffusion coefficients in the dry samples in the temperature range 25 300 k neutron data suggested that hydrogen diffuses in the dry clay rock according to fick s law the findings reported in this work can help to better understand the behavior of h 2 in clay rock samples

comments and reply on sedimentation in a large lake a reinterpretation of the late pleistocene stratigraphy at scarborough bluffs ontario canada reply

decadal changes in the north pacific oceanic frontal zones as revealed in ship and satellite observations 1 influence of decadal climate changes upon the north pacific subarctic and subtropical oceanic frontal zones np safz and np stfz respectively is documented both satellite and ship measured sea surface temperature sst data reveal the strong confinement of wintertime decadal sst anomalies to those frontal zones the satellite data indicate that the wintertime np safz tended to be narrow and shift northward under the weakened surface westerlies during a warm event in the early 1990s the opposite was the case under the enhanced westerlies during a cool event in the mid 1980s decadal scale modulations in the frontal intensity are also evident in the satellite data a diagnosis based on a simple linearized mixed layer model suggests that the observed anomalous frontal intensity was contributed by the sign reversal of anomalous wind stress curl through the ekman processes and by an anomaly dipole of the net heat flux around the safz these decadal scale modulations in the np safz and their relationships with decadal fluctuations in the local surface westerlies are confirmed in the ship measured data over the 4 recent decades it is found that the safz happens to be a region where the decadal variability in the surface westerlies are unlikely to be masked by the higher frequency fluctuations as it almost coincides with the ridge trough line of the remote atmospheric response to the el nino southern oscillation

analysis and reinterpretation of deformation features in the rouge river valley scarborough ontario geometry and timing of deformation affecting ordovician bedrock and overlying pleistocene sediments in the rouge river valley near scarborough ontario are analysed to evaluate whether or not the structures are a result of glacial action or neotectonic activity extensive data on local and regional ice flow directions are used to evaluate the kinematic compatibility between the observed faults and folds and the local ice flow directions jointing and multiple episodes of faulting affect both the ordovician bedrock and the overlying pleistocene sediments at one site the bedrock is displaced by a normal fault by a minimum of 1 2 m crosscutting relationships constrain the majority of the faulting in the rouge river valley as being coeval with deposition of the lower bowmanville till during the nissouri phase ca 23 15 ka and possibly younger at one locality the youngest regional ice flow direction is northwestward however local ice flow directions are highly variable this can be explained by local perturbation enhanced by the presence of drumlinoid features in the area most deformation features are compatible with local and regional ice flow directions glaciotectonic ice push and ice thrust deformation affected the thorncliffe formation after about 23 ka although some faults appear to be kinematically incompatible with ice flow directions six boreholes drilled to 52 m depth revealed only minor vertical offsets of bedrock strata in the uppermost 20 m and an absence of obvious fault offsets deeper precluding the possibility that the faults observed in the surface exposures were caused by deep seated neotectonic stresses

spatio temporal variability of the equatorial front in the eastern tropical pacific from remote sensing salinity data 2010 2015 abstract in the eastern pacific the equatorial front ef separates the relatively cold and salty equatorial surface water to the south from the relatively warm and fresh surface tropical water to the north although previous studies have succinctly described the main ef characteristics little is known about its spatial pattern and temporal variability beyond seasonal scale in this study we used 5 years of remote sensing sea surface salinity sss data acquired by smos in a synoptic and continuous manner to describe the spatio temporal variability of the haline ef hef after validating the sss satellite dataset with concomitant in situ data we developed an algorithm based on maximum sss gradients to automatically identify the hef position on every smos sss map this algorithm applied to the 4 day resolution smos sss product allows us to investigate the spatio temporal variability of the hef between 2010 and 2015 seasonally west of the galapagos islands the hef is centered at 2 n and shows relatively weak meridional displacements in contrast east of the galapagos archipelago the hef varies on average between 4 s in spring and 2 n in autumn at intraseasonal scales the hef shows meridional fluctuations of 1 25 around its average position these intraseasonal fluctuations are partly related to kelvin waves which was more noticeable since 2014 over the 5 year studied period the hef position showed a northward trend of 0 3 0 4 latitudinal degrees per year between 2010 and 2015 however the relatively short time series does not permit to investigate whether this low frequency trend is due to long term variability or interdecadal fluctuations

the pre late wisconsin stratigraphy of southern simcoe county ontario implications for ice sheet buildup decay and great lakes drainage evolution1 recent three dimensional mapping investigations in southern simcoe county ontario allow refinement of the existing regional stratigraphic framework analysis of 25 continuously cored boreholes ha

variability and frontogenesis in the large scale oceanic frontal zones sea surface temperature sst from weekly global advanced very high resolution radiometer data for the period of 1982 1992 and estimates of the surface forcing due to wind stress and net heat flux are used to investigate a global monthly climatology of large scale oceanic frontal zones ofzs the variability of sst gradient in several frontal zones and the meridional frontogenesis in the north pacific subpolar frontal zones are identifiable in the sst gradient field throughout the whole year while subtropical frontal zones appear as seasonal phenomena in the northern hemisphere the magnitude and position of subtropical fronts were found to vary synchronously in both hemispheres with maximum intensity in november to march during this period subtropical fronts in the northern hemisphere become clearly identifiable separate features while in the southern hemisphere their southern boundaries tend to merge with the subpolar front in the northern hemisphere the northward shift of the subtropical frontal zones during late boreal spring results in a merger of the subpolar and subtropical zones by august in the southern hemisphere subtropical fronts separate from the subpolar front during this period and become clearly distinguishable though less intense singular spectrum analysis of the 11 year time series of sst gradient in several ofzs revealed a seasonal signal as well as interannual variations that in the equatorial zone are related to el nino events the amplitude of the annual cycle is comparable in the subtropical and subpolar north pacific but the subtropics leads the subpolar zone by about 4 months combined forcing due to wind stress and net surface heat flux was found to be sufficient to describe most of the observed frontogenesis variability in north pacific midlatitudes on seasonal timescales but not on shorter timescales in the subtropical zone the ekman convergence alone was not sufficient to provide the observed frontogenesis frontolysis on seasonal time scales in fact when the maximum frontogenesis associated with ekman convergence occurs in late spring early summer this is counteracted by the frontolytic effect of ekman pumping and the dominating frontolytic effect of surface heat forcing in summer ekman convergence is more important in the subpolar area where it is enhanced by the smaller frontogenetic effect of both ekman pumping and surface heat forcing surface forcing due to wind stress and heat flux considered in this study does not explain the high amplitude intraseasonal frontogenesis variations especially in the subpolar region

the subarctic frontal zone in the north pacific characteristics of frontal structure from climatological data and synoptic surveys the subarctic front is a thermohaline structure across the north pacific separating colder fresher water to the north from warmer saltier water to the south levitus s 1982 data and 72 conductivity temperature depth salinity temperature depth sections are used to show the spatial and seasonal variations of the climatological frontal zone and the characteristics of the frontal structure in synoptic surveys the temperature gradient in the mean frontal zone is stronger in the western pacific and decreases eastward while the salinity gradient has less variation across the pacific the temperature gradient also has larger seasonal variation with a maximum in spring than the salinity gradient the synoptic surveys show that the frontal zone is narrower and individual fronts tend to be stronger in the western pacific than in the eastern pacific density gradients tend to be more compensated at the strongest salinity fronts than at the strongest temperature fronts a horizontal minimum of vertical stability is found south of the subarctic halocline outcrop the northern boundary of the north pacific intermediate water merges with the frontal zone west of 175 w and is north of the northern boundary of the subarctic frontal zone in the eastern pacific the shallow salinity minima start within the subarctic frontal zone in the eastern pacific

lacustrine ostracodes in the late pleistocene sunnybrook diamicton of southern ontario canada two opposing interpretations have been made on the depositional origin of the late pleistocene sunnybrook diamicton in the metro toronto region of southern ontario the traditional view holds this deposit to be a till but more recent arguments advocate a glaciolacustrine origin by suspension deposition and ice rafting the discovery of a low diversity ostracode fauna consisting of candona subtriangulata candona caudata and darwinula stevensoni in the sunnybrook diamicton suggests a lacustrine origin excellent preservation of thin fragile shells and a mixture of juveniles and adults in sediments of varying texture clayey silt to silty clay indicate that there has been little winnowing or selective sorting and that the ostracodes are in situ indications are that the sunnybrook diamicton was deposited in a large deep and cold lake these new palaeontological observations call for a reassessment of the quaternary stratigraphy of the ontario basin and suggest that the laurentide ice sheet in the eastern

comments and reply on sedimentation in a large lake a reinterpretation of the late pleistocene stratigraphy at scarborough bluffs ontario canada comment

multiscale phenomena in the tropical atmosphere over the western pacific abstract multiscale variabilities in the atmosphere over the tropical western pacific during the 1979 northern hemisphere winter are studied with an aim at identifying possible interactions between phenomena of different spatial and temporal scales based on the convection index information derived from satellite measurements two intra seasonal oscillations isos are identified within the equatorial belt between 0 and 10 s in the analyzed period the two isos accompanied by both rotational and divergent circulations propagate eastward from the indian ocean to the western pacific over the warm pool in the western pacific the isos develop into quasi stationary systems with an enhanced rotational circulation characterized by a strong westerly jet in the lower troposphere the isos appear to interact with a number of regional and synoptic scale phenomena in the maritime continent and western pacific region for example the onset of the monsoon coincides with the arrival of the first iso at northern a

variability of the climatic oceanic frontal zones and its connection with the large scale atmospheric forcing abstract global satellite sea surface temperature sst measurements and ncep ncar reanalysis wind data for the period of 1982 2009 have been used to study the seasonal and interannual variability of the main climatic oceanic frontal zones ofz subpolar subtropical and equatorial associated with the large scale atmospheric forcing the seasonal variability of the ofz is manifested in variations of their intensity magnitude of the meridional gradient of sst and latitudinal position of the cores defined as areas of maximum sst gradient the maximum intensity of the subpolar ofz is observed in summer of the corresponding hemisphere while subtropical ofz are intensified synchronously in both hemispheres during boreal winter subtropical ofz cores in both hemispheres shift synchronously to the south north during the winter summer of the northern hemisphere which is caused by the seasonal meridional migration of the areas of the maximum convergence of ekman transport all subpolar and subtropical ofz reveal a pronounced quasi decadal 7 10 years variability manifested in the variations of their intensity and latitudinal position of the zones cores strengthening of the sst gradient is accompanied by a displacement of the zones cores to the north in both hemispheres for subpolar ofz while subtropical ofz cores migrate to the poles in this situation positive correlations between the maximum magnitude of the meridional gradient of zonally averaged sst and meridional shear of zonal wind which is an estimate of the ekman convergence intensity were found for all subpolar and subtropical ofz variability of the latitudinal position of subpolar ofz cores is associated with the ekman advection variability due to zonal wind variations strengthening of zonal wind results in a shift of subpolar ofz cores to the south north in the northern southern hemispheres a period of the variability of the north pacific equatorial ofz is 4 5 years and is determined by the variability of the enso system during the el nino events the sharp decrease of the intensity of the equatorial ofz take place

frontogenesis in the north pacific oceanic frontal zones a numerical simulation abstract a primitive equation model geophysical fluid dynamics laboratory s gfdl s mom 2 with one degree horizontal resolution is used to simulate the seasonal cycle of frontogenesis in the subarctic frontal zone safz and the subtropical frontal zone stfz of the north pacific ocean the safz in the model contains deep greater than 500 m in some places regions with seasonally varying high gradients in temperature and salinity the gradients generally weaken toward the east the stfz consists of a relatively shallow less than 200 m in most places region of high gradient in temperature that disappears in the summer fall the high gradient in salinity in the stfz maintains its strength year round and extends across almost the entire basin the model simulates the location and intensity of the frontal zones in good agreement with climatological observations generally to within two degrees of latitude and usually at the same or slightly stronger intensity the seasonal cycle of the frontal zones al

intensification of the subpolar front in the sea of japan during winter cyclones the response of the subpolar front in the sea of japan also known as the east sea to winter cyclones is investigated based on quantitative analyses of gridded and satellite data sets cyclone passages affecting the sea are detected using time series of spatially averaged surface turbulent heat fluxes as the cyclones develop there are strong cold air outbreaks that produce twice the normal heat loss over the sea after removal of sea surface temperature sst seasonal trends we found that cyclone passage hence cooling mainly occurred over 3 days with maximum sst reduction of 0 4 c the greatest reduction was found along the subpolar front where frontal sharpness i e sst gradient increased by 0 1 c 100 km 1 results of a mixed layer model were consistent with both temperature and frontal sharpness and localized surface cooling along the subpolar front resulted from both horizontal heat advection and turbulent heat fluxes at the sea surface further analyses show that this localized cooling from horizontal heat advection is caused by the cross frontal ekman flow vertically averaged over the mixed layer and strong northwesterly winds associated with the cold air outbreak during cyclone passage

late quaternary stratigraphy and geochemistry of the r47 section rouge river basin south central ontario canada correlation with scarborough bluffs quaternary glacial diamictons in section r47 overlying ordovician shale in the rouge river basin of south central ontario are considered to be representative of older and younger wisconsinan glacial diamictons in the field area field characteristics clast composition mineralogy particle size and geochemistry permit delineation of two units within the sequence and subdivision of deposits that correlate with sunnybrook and halton diamictons of wisconsinan age no wisconsinan interstadial deposits are present in the section however outwash sandy gravel capping the halton diamicton was probably emplaced by a high energy stream draining into lake lroquois just prior to the incision of the rouge valley in the later wisconsinan ca 11000 12000 yr bp a buried palaeosol which developed in this sandy gravel and in overlying aeolian sediment shows partial leaching of carbonates and a slight increase of clay in the palaeosol solum the main clay mineral transformations in the buried palaeosol appear to involve the degradation of illite and illite smectite accompanied by the production of vermiculite and minor amounts of chlorite the ground soil capping the buried palaeosol is formed in colluvium emplaced 200 f b0 yr bp following a local forest fire the ground soil ahk horizon gives an age of 4000 yr in the future probably as a result of nuclear bomb testing effects on modern radiocarbon the presence of an fuc profile in the ground soil system although thin indicates that surface soils may form rapidly the geochemistry of the two wisconsinan diamictons shows similar calcite and sior corrected mean element concentrations with slightly elevated levels of ca sr hf and lu in the younger deposit both diamictons are geochemically quite different from the shale bedrock in the area indicating that the bulk of transported sediment came from outside the area of quaternary kierrce itit

causes of the large warm bias in the angola benguela frontal zone in the norwegian earth system model we have investigated the causes of the sea surface temperature sst bias in the angola benguela frontal zone abfz of the southeastern atlantic ocean simulated by the norwegian earth system model noresm similar to other coupled models noresm has a warm sst bias in the abfz of up to 8 c in the annual mean our analysis of noresm reveals that a cyclonic surface wind bias over the abfz drives a locally excessively strong southward 0 05 m s relative to observation angola current displacing the abfz southward a series of uncoupled stand alone atmosphere and ocean model simulations are performed to investigate the cause of the coupled model bias the stand alone atmosphere model driven with observed sst exhibits a similar cyclonic surface circulation bias while the stand alone ocean model forced with the reanalysis data produces a warm sst in the abfz with a magnitude approximately half of that in the coupled noresm simulation an additional uncoupled sensitivity experiment shows that the atmospheric model s local negative surface wind curl generates anomalously strong angola current at the ocean surface consequently this contributes to the warm sst bias in the abfz by 2 c compared to the reanalysis forced simulation there is no evidence that local air sea feedbacks among wind stress curl sst and sea level pressure slp affect the abfz sst bias turbulent surface heat flux differences between coupled and uncoupled experiments explain the remaining 2 c warm sst bias in noresm ocean circulation upwelling and turbulent heat flux errors all modulate the intensity and the seasonality of the abfz errors

lithofacies types and vertical profile models an alternative approach to the description and environmental interpretation of glacial diamict and diamictite sequences abstract increased knowledge of modern glacial depositional environments has resulted in rapidly evolving classifications of glacial tills these are based to a large degree on theoretical considerations of likely depositional processes the classifications are sophisticated and more advanced than the establishment of simple field criteria whereby individual till facies can be identified in quaternary and pre quaternary successions this situation is compounded in many quaternary terrains by the continued description of tills in terms of laboratory derived analytical data only reflecting a traditional interest in stratigraphic correlation rather than reconstruction of depositional environment detailed sedimentological logging of lithofacies is rarely undertaken there is thus considerable confusion as to what is being described or sampled when analytical data are presented for many pleistocene tills the same remarks apply to pre pleistocene tillites a lithofacies code is presented here for the rapid description and visual appraisal of field sequences or drill cores containing unconsolidated diamicts or lithified diamictites the term till is not used as it has a strict genetic definition referring to direct aggregation and deposition by glacier ice use of a four part code in conjunction with codes already published for fluvial sediments allows fundamental field properties to be depicted independent of genetic terminology and provides a firm basis for subsequent environmental interpretation and analytical work the value of this approach is illustrated by comparing a representative suite of vertical profiles of diamict assemblages deposited by modern grounded glaciers with a classic late pleistocene glacigenic sequence at scarborough bluffs ontario

decadal variability of the subtropical front of the western north pacific in an eddy resolving ocean general circulation model 1 we examined decadal variability of the subtropical front stf of the western north pacific by using a north pacific ocean general circulation model ogcm comparing the results of three simulations with different horizontal resolutions in the long term mean fields the eddy resolving model 10 km was able to simulate the distributions of the stf and the associated subtropical countercurrent stcc between 20 n and 30 n better than either the non eddy resolving model 100 km or the eddy permitting model 20 km because it simulated the kuroshio recirculation gyre more realistically the simulated stf intensity exhibited significant decadal scale variations it was stronger in the late 1970s and weaker in the early 1990s during these two periods the simulated mode waters showed corresponding differences in their potential vorticity minima density and paths we also investigated the relationship between the decadal scale stf variability and atmospheric forcing the results suggest that the decadal scale stf variability can be largely explained by changes in the mode waters formed in the western north pacific and advected to north of the stf by the subtropical gyre in response to a change in surface westerly winds that occurred in the mid 1970s

the spatial distribution and annual cycle of upper ocean thermohaline structure 1 observations of the spatial distribution and persistence of thermohaline structure are presented and show how advection and diffusion affect a passive tracer more than two years of underwater glider observations in the central subtropical north pacific showed thermohaline variability over horizontal scales from 5 to 1300 km thermohaline fluctuations along isopycnals spice fluctuations were elevated in layers throughout the water column with the largest fluctuations near the surface and subtropical frontal regions fluctuations were uncorrelated between the layers but stirred by the same velocity field spice variance had local extrema in the vertical because of differences in source water properties and the influence of neighboring water masses spice variance spanned about three orders of magnitude along deeper isopycnals with larger variance where different water masses met and where velocity and vorticity variance were elevated horizontal wave number spectra of spice had slopes of 2 everywhere in the upper 1000 m submesoscale spice fluctuations had slopes in physical space near the ratio of the coriolis parameter to the buoyancy frequency f n consistent with predictions of quasi geostrophic theory in the mixed layer thermohaline structure had a significant annual cycle with smaller interannual differences thermohaline fluctuations left behind during restratification and isolated from the mixed layer decayed with time because of diffusion along isopycnals horizontal diffusivity estimates in the remnant mixed layer were 0 4 m2 s 1 at 15 28 km wavelengths and 0 9 m2 s 1 at 35 45 km wavelengths

ostracod faunas in a large late pleistocene ice dammed lake southern ontario canada abstract in the lake ontario basin of mid continent north america near toronto canada a low diversity micro crustacean ostracod community dominated by candona caudata and candona subtriangulata occurs in several poorly sorted pebbly mud diamicts units sunnybrook seminary and meadowcliffe tills the diamicts were deposited in an ancestral ice dammed lake ontario with a level at least 90 m above the modern lake during the early and middle phases of the wisconsin glaciation 25 000 75 000 yr b p poorly sorted sediments accumulated by ice rafting and mud deposition from meltwater plumes and are separated by shallower water deltaic facies comparison of the modern habitat ranges of ostracods specifically their water depth temperature and dissolved oxygen preferences provides important palaeolimnological data regarding late pleistocene ice dammed lakes

pleistocene glacio lacustrine deltaic deposits of the scarborough formation ontario canada abstract the late pleistocene scarborough formation of the lake ontario basin represents a lacustrine deltaic sequence strongly affected by a nearby glacier it shows gradual upward coarsening and thickening of layers from varve like clay rich rhythmites at the base to channelized cross bedded sands at the top thick lensing massive layers cm of silty sand are found interstratified with thin layers of silt and clay in the lower and middle parts of the sequence these massive layers were probably formed by subaqueous gravity flows of material in part derived directly from a glacier absence of pebbles and of other features such as glacial silt pellets suggests dispersal away from the foot of the glacier rather than deposition under floating ice varve like rhythmites pollen and insect fauna indicate subarctic to arctic climatic conditions at the time of sediment deposition the large amount of sand in the upper part of the formation is best explained as derived from active outwash fans similar fans were formed during the last deglaciation in southern ontario and can be observed on the landscape

depositional controls on the magnetic characteristics of lodgement tills and other glacial diamict facies genetic interpretation of massive unstructured diamict and diamictite facies is a commonly encountered problem faced by sedimentologists data are presented concerning the magnetic characteristics namely anisotropy of magnetic susceptibility ams and natural remanent magnetism nrm of facies deposited by 1 lodgement processes at a glacier base lodgement till and 2 subaqueously by pelagic mud deposition and ice rafting rain out diamicts lodgement tills have an nrm that is distorted around the geomagnetic pole position to form a girdle approximately 90 in length either transverse or parallel to ice flow direction this distension appears to be the result of subglacial shear processes because other diamicts deposited passively by melt out below stagnant ice and modelled by a laboratory experiment show a nondeformed nrm clustering around the geomagnetic pole the ams data show that lodgement tills have only a weakly orientated magnetic microfabric glaciolacustrine rain out diamicts show

interannual variability of the north pacific subtropical countercurrent and its associated mesoscale eddy field interannual changes in the mesoscale eddy field along the subtropical countercurrent stcc band of 188 258n in the western north pacific ocean are investigated with 16 yr of satellite altimeter data enhanced eddy activities were observed in 1996 98 and 2003 08 whereas the eddy activities were below average in 1993 95 and 1999 2002 analysis of repeat hydrographic data along 1378e reveals that the vertical shear between the surface eastward flowing stcc and the subsurface westward flowing north equatorial current nec was larger in the eddy rich years than in the eddy weak years by adopting a 2 layer reduced gravity model it is shown that the increased eddy kinetic energy level in 1996 98 and 2003 08 is because of enhanced baroclinic instability resulting from the larger vertical shear in the stcc nec s background flow the cause for the stcc nec s interannually varying vertical shear can be sought in the forcing by surface ekman

large scale sst variability in the western north atlantic subtropical convergence zone during fasinex part i description of sst and wind stress fields abstract we describe properties of large scale fluctuations in the wind field represented by two analyses fnoc and noaa atoll and in the sst field represented by maps derived from 5 day composite avhrr images within an 11 longitude by 10 latitude domain during fasinex january through june 1986 fnoc and atoll wind and wind stress time series were highly correlated with each other 0 8 over the entire domain and they were also highly correlated with time series measured at the fasinex site 0 89 at periods of 2 13 days clockwise energy exceeded anticlockwise energy by an order of magnitude while the energy was nearly partitioned equally at periods of 13 40 days mean atoll winds were everywhere more eastward than mean fnoc winds probably in part because the atoll fnoc analyses are intended to represent 850 mb 19 5 m winds the 850 mb winds are expected to be more eastward due to the thermal wind balance with the mean southward air temperature gradient the sst maps represented large s

the subarctic and northern subtropical fronts in the eastern north pacific ocean in spring abstract the subarctic and subtropical frontal zones of the eastern north pacific ocean were surveyed in june for five consecutive years starting in 1972 these surveys from the basis for a description of the complex frontal distributions and their year to year differences the fronts appear as surface outcroppings of haloclines the subarctic halocline where salinity increases with depth and the subtropical halocline where the opposite prevails between the fronts lies a transition zone where strong vertical gradients of salinity are generally absent an examination of the northern boundary of subtropical waters in this new dataset reveals the presence of two major fronts in the subtropical frontal zone in addition to the front commonly identified as the subtropical front 18 c and 34 8 is a northern subtropical front that forms the northern boundary of the subtropical halocline in the eastern north pacific it falls some 2 to 3 of latitude north of the subtropical front and is the same front observ

large scale sst variability in the western north atlantic subtropical convergence zone during fasinex part ii upper ocean heat balance and frontogenesis abstract we analyzed the influence of wind deriven horizontal heat advection on the large scale o 1000 km wavelength variability of both the upper ocean mixed layer heat content and the subtropical frontal zone sfz within an 11 by 10 domain in the western north atlantic ocean during fasinex january through june 1986 by estimating heat advection due to both ekman transport and interior geostrophic sverdrup minus ekman transport from a slab mixed layer heat balance equation using satellite derived sea surface temperature ts and wind analysis maps it was found that these processes could not account for the observed variability in either beat content or the sfz the annual cycle of surface vertical heat flux had the dominant influence on the heat content even when the average heat balance was analyzed during a 4 month time interval when the net influence of the annual cycle was nearly zero mid january to mid may 1986 westward propagating ts spatial anomaly features with peak to peak scales

westward propagating sst anomaly features in the sargasso sea 1982 88 abstract sea surface temperature ts maps of the region from 59 5 to 75 5 w 22 5 to 33 5 n containing the western north atlantic subtropical convergence zone stcz were derived from avhrr 2 images the 7 year mean annual cycle was removed and the maps were filtered in space and time to represent anomaly variability with wavelengths 220 km and periods 50 days warm and cold anomaly features were observed cast of 71 w between 26 and 32 n that propagated westward at 3 4 km day 1 and that occasionally exceeded 1 c in amplitude they are generally strong and persistent from fall to spring and are only marginally detectable during summer during 1981 82 1982 83 and 1985 86 individual features could be followed through the entire fall spring interval during 1983 84 1986 87 and 1987 88 they could typically be followed for 2 4 months and during 1984 85 for only 1 2 months the features were anisotropic during all fall spring intervals except 1986 87 and they had characteristic wavelengths of 80

concurrent decadal mesoscale eddy modulations in the western north pacific subtropical gyre abstractsatellite altimeter data of the past two decades are used to investigate the low frequency mesoscale eddy variability inside the western north pacific subtropical gyre eddy activity modulations with a decadal time scale are detected concurrently within the 18 28 n band including the three branches of the subtropical countercurrent stcc and the hawaiian lee countercurrent hlcc lagging behind the pacific decadal oscillation pdo index by six months enhanced eddy activities were detected in 1995 98 and 2003 06 whereas the eddy activities were below the average in 1999 2002 and 2009 11 analysis of the temperature and salinity data that became available after 2001 via the international argo program reveals that the modulating eddy activities are due to the decadal change in the upper ocean eastward shear in the broad scale stcc hlcc band by conducting an upper ocean temperature budget analysis the authors found that this observed eastward shear change can be effectively accounted for by t

laboratory experiments on shear failure of snow using a direct simple shear apparatus snow samples 115 mm in diameter 16 18 mm in height taken from a so called homogeneous layer small rounded particles density 290 kg m 3 were tested in a cold laboratory experiments were performed for strain rates between 7 10 6 s 1 and 5 10 3 s 1 at test temperatures of 5 c 10 c and 15 c the effects of strain rate and temperature on failure stress failure strain stiffness initial tangent modulus and toughness were studied the transition between the ductile and brittle sudden fracture state of failure was found to be at about 1 10 3 s 1 for the snow types tested independent of temperature stiffness proved to be the most temperature dependent property of alpine snow it strongly increases with decreasing temperature failure strain and toughness decrease with decreasing temperature failure stress was found to increase slightly with decreasing temperature the effect is not very distinct but close to statistically significant and might be partly hidden by the scatter in the stress data due to variations inherent in sampling and testing

redox reaction of aqueous selenite with as rich pyrite from jiguanshan ore mine china reaction products and pathway the interaction of an as rich natural pyrite fes2 08as0 043 with aqueous se iv was investigated as a function of ph ferrous iron concentration and reaction time arsenic is often the most abun

on the characteristics of subtropical fronts in the north atlantic 1 the characteristics of surface temperature sst fronts in the subtropical frontal zone stcz in the north atlantic were investigated using a time series of front data produced by an edge detection algorithm applied to 18 years of 9 3 km resolution noaa nasa avhrr pathfinder sst imagery front probability averaged over subregions of the stcz varies seasonally with highest probability in early spring in the western part of the region in the eastern part of the region maximum probability occurs in late spring to early summer and the annual cycle in front probability is far less robust being nearly absent prior to 1991 the location and strength of the fronts across the entire stcz varies strongly with season moving southward northward and strengthening weakening in winter spring summer from estimates of the cross frontal sst step and gradient the cross frontal scale of sst variability at fronts is estimated to be approximately 30 km the monthly mean total meridional sst step across the stcz is partitioned into a component due to frontal pixels and a component due to the background sst gradient at nonfrontal pixels with approximately 30 of the total step attributable to the sst step across fronts while the total meridional step is largest in winter due to the meridional gradient in surface heat flux the frontal contribution lags the total step by 2 months or more in the western part of the stcz this suggests a frontogenesis mechanism requiring the presence of a background meridional sst gradient rather than one arising from surface heat flux gradients alone