further evidence for inclination shallowing in red beds red beds and related shallow marine siliciclastic sediments within the extensional catalan neogene basins offer a unique opportunity to study the relationship between sediment anisotropy remanence acquisition and inclination shallowing on the basis of the dominant fabric features sedimentary facies are grouped into laminated massive and bioturbated the bulk susceptibility appears to be dominated by paramagnetic phyllosilicates and clay minerals the magnetic susceptibility fabric is dominantly foliated while the degree of anisotropy is very variable and is dependent on the facies type strong foliation dominates in the laminated sediments whereas weak anisotropy characterizes the bioturbated and massive mass flow facies moreover we observe a correlation between facies type and remanence inclination the undisrupted thinly laminated facies provides the most biased inclination values 20 as opposed to 60 of the expected geomagnetic field steeper inclinations are reported from bioturbated muds while the best record of the geomagnetic inclination is found in the weakly anisotropic mass flow deposits

a comparison of shear and buoyancy driven planetary boundary layer flows abstract planetary boundary layer pbl flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces these differences are not unexpected in that shear instabilities occur locally while buoyancy force sets up vigorous thermals which result in nonlocal transport of heat and momentum at the same time these two forces can act together to modify the flow field in this study four large eddy simulations less spanning the shear and buoyancy flow regimes were generated two correspond to the extreme cases of shear and buoyancy driven pbls while the other two represent intermediate pbls where both forces are important the extreme cases are used to highlight and quantify the basic differences between shear and convective pbls in 1 flow structures 2 overall statistics and 3 turbulent kinetic energy tke budget distributions results from the two intermediate les cases are used to develop and verify a velocity scaling and a tke budget mode

palaeomagnetism of the early carboniferous deer lake group western newfoundland no evidence for mid carboniferous displacement of acadia early carboniferous visean to possibly earliest namurian sedimentary rocks of the deer lake group of western newfoundland rest unconformably on grenvillian basement rocks of the canadian shield which form the western border of the early palaeozoic appalachian orogen in addition to magnetically soft magnetizations directed along the present field three families of magnetization directions are found two of them referred to as n north and s south are antiparallel and prefolding and were probably acquired during the depositional process n and s are roughly of equal frequency they have a mean direction irrespective of sign of 0 7 35 2 k 40 95 8 9 and a palaeopole 21 5 n 121 8 e 10 3 6 0 corresponding to a palaeolatitude of 20 6 s this agrees with the palaeolatitude 17 5 s determined from the somewhat older early carboniferous tournaisian terenceville formation of the avalon platform on the eastern side of the appalachian orogen in newfoundland the third magnetization referred to as h roughly horizontal has a mean direction 156 8 13 3 k 37 95 10 1 and a palaeopole 45 4 n 140 3 e 10 3 5 3 corresponding to a palaeolatitude of 7 4 n we interpret this to be an early kiaman latest carboniferous to early permian overprint probably acquired chemically the palaeolatitude determined from the h overprint agrees with that determined from early carboniferous rocks of cratonic north america west of the appalachians therefore we argue early carboniferous palaeofield determinations for cratonic north america have been strongly biased by unremoved kiaman overprints because of this and because of the good agreement between early carboniferous palaeolatitudes obtained from opposite margins of the appalachian orogen we suggest that there is at present no palaeomagnetic evidence for the previously proposed 1500 km displacement from the south of an eastern portion of the appalachians acadia relative to cratonic north america during the carboniferous

dual polarity early carboniferous remagnetization of the fisset brook formation cape breton island nova scotia summary red siltstones and volcanic flows of the fisset brook formation of cape breton island nova scotia were folded or tilted in two phases one of late tournaisian and the other of mid namurian age upon thermal demagnetization both rock types yield three components of magnetization herein denoted as l i and h the l component has low unblocking temperatures and a direction conforming to that of the present day geomagnetic field l is inferred to be of recent origin the intermediate i component carried by haematite is of synfolding origin directions could be obtained through vector subtraction for the demagnetization interval of 300 550 c and yield a mean of d i 160 38 k 90 8 ag5 s lo after 39 per cent of the tilt correction is applied the h component has even higher unblocking temperatures which overlap to a large degree with those of the i component but analysis of intersecting great circles appears to yield a best fit direction for h which is nearly antipodal to that of the i component h is also synfolding and yields a mean direction of d i 342 38 k 120 9 ag5 6 9 after 60 per cent of tilt correction both components are interpreted as secondary chemical remanent magnetizations of late tournaisian to early namurian age a comparison of all available carboniferous results from the craton and the northern appalachians indicates that palaeolatitudes for nova scotia changed from about 20 s to about 10 s in the interval between the early and late namurian and that they changed again from about 10 s to 0 between the late namurian and the stephanian declinations show good agreement between newfoundland nova scotia new brunswick and the craton with the exception of the meguma terrain which underwent a counterclockwise rotation with respect to the mainland in the late carboniferous as noted previously by spariosu kent keppie 1984

large scale particle image velocimetry for low velocity and shallow water flows large scale particle image velocimetry lspiv is an extension of quantitative imaging techniques for measurements of water surface velocities using inexpensive standard video equipment the present technical note describes capabilities and limitations of lspiv for low velocity shallow flows measurements in low velocity shallow flume flows were performed to investigate the lspiv sensitivity to seeding density and time interval between successive images the results show that the accuracy of the lspiv technique does not deteriorate as the flow velocity is reduced to as low as 0 015 m s provided an adequate seeding and suitable time difference between images are selected the results suggest that lspiv is well suited for flow fields with small velocities that are often below the limit of detection of most conventional devices

observations of wind shear over the southern ocean 1 the thermodynamic structure of the lower troposphere over the southern ocean is analyzed by employing over 16 years of high resolution upper air soundings from macquarie island 54 62 s 158 85 e the soundings are analyzed to develop an understanding of the structure of the boundary layer and wind shear occurring through the lower levels over this region and to compare this to european centre for medium range weather forecasts ecmwf model level reanalysis data for the year of tropical convection yotc a multiple layered structure is commonly observed in the high resolution soundings and is also observed in yotc but with a lower frequency the climatological mean and variability of a number of variables are calculated for both data sets which reveals that yotc performs well but has weaknesses in modeling the observed moisture and wind fields particularly evident in wind shear profiles a distinction between a number of boundary layer types is made and the frequency with which they occur is quantified for both data sets this highlights important differences between the observations in the macquarie island soundings and the reanalysis product proxy cloud fields are constructed for the two data sets and these suggest that clouds are commonly observed in a region between the top of the boundary layer and a secondary temperature inversion i e a buffer layer in the words of russell et al 1998 the peak relative frequency of observing these clouds lies roughly around 912 5 hpa for both data sets an examination of the wind shear across the cloud boundaries finds wind shear over cloud base occurs more frequently than cloud top suggesting that the cloud fields are not embedded in a well mixed boundary layer

wind turning across the marine atmospheric boundary layer the directional wind turning across the boundary layer in short range forecasts made as part of the recent era 40 reanalysis project is compared with radiosonde data from oceanic stations in the north atlantic significant errors are identified particularly in cases of warm advection in which it is found that the observed wind turning is systematically underestimated similar problems are found in the higher resolution operational forecasts and also in forecasts made with the independent met office model furthermore comparisons of forecast wind direction with scatterometer data give consistent results over the north atlantic and indicate that the same problems are present over other oceans a large fraction of the cases with the largest errors are shown to have stable boundary layers in these cases the modelled boundary layers are typically too deep and sensitivity tests have shown that more realistic structures are obtained by switching to a stable boundary layer parametrization based on monin obukhov similarity some possible problems with the convective boundary layer parametrization in highly baroclinic conditions are also identified copyright 2005 royal meteorological society

investigating the role of clasts on the movement of sand in gravel bed rivers the bed morphology of mountain rivers is characterized primarily by the presence of distinguishable isolated roughness elements such boulders or clasts the objective of this experimental study was to provide a unique insight into the role of an array of clasts in regulating sand movement over gravel beds for low relative submergence conditions h dc 1 and flow depth h to the diameter of the clast dc a process that has not been studied thoroughly to assess the role of clasts in controlling incoming sand movement detailed flume experiments were conducted by placing 40 equally spaced clasts atop a well packed glass bead bed for replicating the isolated roughness flow regime the experiments were performed for moderate 2 50 cr where cr is the critical dimensionless bed shear stress and high 5 50 cr applied bed shear stress conditions representative of gravel bed rivers for comparison purposes experiments were also repeated for nearly identical flow conditions but without the presence of

paleomagnetism of fluorite veins in the devonian st lawrence granite newfoundland canada paleomagnetic results are reported from the devonian st lawrence granite and the fluorite veins within the granite or its related porphyry dikes paleomagnetic analysis of 359 specimens from 29 sites shows that there is no statistically significant difference at 95 confidence between the site mean characteristic remanent magnetization chrm directions carried by pyrrhotite and or magnetite of the granite and fluorite veins no post granite metamorphic event is known in the area thus these concordant directions indicate that the granite and fluorite veins are coeval and retain a primary remanence however the mean chrm direction of 25 vein and granite sites yields an early pennsylvanian paleopole of 316 ma on the north american apparent polar wander path at 35 5 n 129 2 e a95 3 4 that is younger than the 374 2 ma devonian u pb zircon age for the granite two intersecting vertical vein sets indicate that the st lawrence granite has not been tilted since emplacement of the fluorite veins t

automated extraction of pack ice motion from advanced very high resolution radiometer imagery multiple subarea cross correlations have been computed from visible advanced very high resolution radiometer images of the beaufort sea in an automated technique to detect pack ice motion the computational method is an application of the well known matched filter and consists of subdividing the first image into a set of subareas and correlating each reference subarea against the appropriate region of the second image the correlation functions are processed to determine a set of local maxima which define end point vectors of ice displacements from the subarea centers resulting velocities agree well with estimates of ice movement obtained by manually measuring invariant ice feature displacements the velocity fields show the spatial structures of ice motion over scales of 100 500 km with a high degree of pattern consistency and agreement with simple surface wind driving

aircraft observations of the ekman layer during the joint air sea interaction experiment results are presented from an observational study of the mid latitude atmospheric boundary layer over the sea the data were obtained mainly by instrumented aircraft as part of the joint air sea interaction experiment jasin the eight occasions chosen for study are characterized by small surface buoyancy fluxes and the conditions are well described as near neutral and barotropic in the absence of low level inversions a well mixed ekman layer is observed on each occasion but is limited to a depth of approximately 0 2u f accurate measurements of horizontal gradients including pressure together with improved wind observations and turbulent flux measurements enabled each of the terms of the momentum balance to be evaluated throughout the depth of this layer these terms were found to balance quite closely were well described by ekman scaling and were consistent with the requirements of the measured turbulent kinetic energy balance the latter suggests that the main shear production terms are dissipated locally and that little is exported to upper levels in the ekman layer to enable significant deepening by entrainment although only a slight increase in instability appears to be needed to alter this balance conditions in which such boundary layer structure might be observed are suggested values of various coefficients used in schemes for relating surface fluxes to mean quantities cd ce cg a b are derived and compared with previous measurements spectral analysis reveals that most of the turbulent transport is confined to a distinct high wavenumber region whose characteristics vary as a function of ekman layer depth and stability parameters this is superimposed on larger scale fluctuations which do not vary appreciably within the ekman layer and which therefore dominate the variances in the upper regions as the intensity of the smaller scale turbulence decreases strongly with height finally further implications of this interpretation are discussed with particular reference to the heat and water vapour balance these imply that removal of water vapour from the ekman layer is accomplished by transfer related to cloud activity marking a significant change in the mechanism of turbulent transport at the top of this layer the relationship between these and similar results obtained concurrently by different methods is also discussed

paleomagnetism of the lawrenceton formation volcanic rocks silurian botwood group change islands newfoundland paleomagnetic sampling of the lawrenceton formation of the silurian botwood group in northeastern newfoundland was combined with detailed structural mapping of the area in order to determine the deformation history and make adequate structural corrections to the paleomagnetic data structural analysis indicates that the lawrenceton formation experienced at least two folding events i a regional northeast southwest trending siluro devonian folding episode that produced a well developed axial plane cleavage and ii an episode of local north trending folding bedding regional cleavage relationships indicate that the latter event is older than the regional folding thermal demagnetization of the lawrenceton formation yielded univectorial southerly and shallow directions in situ a fold test on an early mesoscale fold indicates that the magnetization of the botwood postdates this folding event however our results combined with an earlier paleomagnetic study of nearby lawrenceton formation rocks demo

paleomagnetism of the distal member of the new glasgow formation nova scotia canada new constraints on magnetic polarity stratigraphy near the base of the kiaman superchron abstract the ca 315 260 ma kiaman reversed permo carboniferous magnetic superchron is an important time marker that can be used for correlation of stratigraphic sequences from a local to a global scale earlier workers from a paleomagnetic study of the joggins stratigraphic section of the western cumberland basin of nova scotia demonstrated that the base of the superchron lies above redbeds of the lowermost portion of the late namurian westphalian a boss point formation although a detailed sequence of reversals was observed below this point no normal magnetic polarity zones were recognized above it in our study samples were collected from redbeds of the distal member of the westphalian a new glasgow formation of the eastern cumberland basin which directly overlie the gray sandstones of the boss point formation most sampling sites carry a normal polarity magnetization probably acquired at about the time of deposition therefore the base of the kiaman reversed superchron lies within or above th

a modeling case study of mixed phase clouds over the southern ocean and tasmania abstract the cloud structure associated with two frontal passages over the southern ocean and tasmania is investigated the first event during august 2006 is characterized by large quantities of supercooled liquid water and little ice the second case during october 2007 is more mixed phase the weather research and forecasting model wrfv2 2 1 is evaluated using remote sensed and in situ observations within the post frontal air mass the thompson microphysics module is used to describe in cloud processes where ice is initiated using the cooper parameterization at temperatures lower than 8 c or at ice supersaturations greater than 8 the evaluated cases are then used to numerically investigate the prevalence of supercooled and mixed phase clouds over tasmania and the ocean to the west the simulations produce marine stratocumulus like clouds with maximum heights of between 3 and 5 km these are capped by weak temperature and strong moisture inversions when the inversion is at temperatures warmer

marine atmospheric boundary layer height over the eastern pacific data analysis and model evaluation the atmospheric boundary layer abl height h is a crucial parameter for the treatment of the abl in weather and climate models about 1000 soundings from 11 cruises between 1995 and 2001 over the eastern pacific have been analyzed to document the large meridional zonal seasonal and interannual variations of h in particular its latitudinal distribution in august has three minima near the equator in the intertropical convergence zone itcz and over the subtropical stratus stratocumulus region near the west coast of california and mexico the seasonal peak of h in the itcz zone between 5 68 and 11 28n occurs in the spring february or april while it occurs in august between the equator and 5 68n comparison of these data with the 10 yr monthly output of the community climate system model ccsm2 reveals that overall the model underestimates h particularly north of 208n in august and september directly applying the radiosonde data to the ccsm2 formulation for computing h shows that at the original vertical resolution with the lowest five layers below 2 1 km the ccsm2 formulation would significantly underestimate h in particular the correlation coefficient between the computed and observed h values is only 0 06 for cloudy cases if the model resolution were doubled below 2 1 km however the performance of the model formulation would be significantly improved with a correlation coefficient of 0 78 for cloudy cases

high spatial resolution mapping of surface velocities and depths for shallow overland flow point measurements of flow rate depth or velocity are not sufficient to validate overland flow models particularly when the interaction of the water with the soil surface creates a complex flow geometry in this study we present the coupling of two techniques obtaining spatial data of flow depths and surface velocity measurements for water depths as low as 1 mm overland flow experiments were performed in the laboratory at various flow rates and slopes on two surfaces the first surface was 120 cm by 120 cm showing three undulations of sinusoidal shape with an amplitude of 1 cm and a wavelength of 20 cm while the second was a 60 cm by 60 cm moulded reproduction of a seedbed with aggregates up to 2 cm in size large scale particle image velocimetry lspiv was used for velocity measurements with a sub centimetre spatial resolution an instantaneous profile laser scanner was used to map flow depths with a sub millimetre spatial resolution a sensitivity analysis of the image processing of the lspiv showed good robustness of the method comparison with measurements performed with hot film anemometer and salt velocity gauge showed that lspiv surface velocities were representative of the flow water depths measured with the laser scanner were also in good agreement with single point measurements performed with a dial indicator spatially distributed flow rates could be computed by combining both presented techniques with a mean relative error less than 20 copyright 2012 john wiley sons ltd

genesis of the st lawrence fluorspar deposits as indicated by fluid inclusion rare earth element and isotopic data more than 40 separate fluorspar veins are associated with the lower carboniferous st lawrence granite of southeastern newfoundland with more than 3 4 million short tons mined since 1933 and a further 9 million short tons of reserves contained in the three main veins it is estimated from these tonnages that fluorine concentrations in the magma of only 19 ppm would have been adequate to form the veins much less than the average of 1 567 ppm f found in the granite fluid inclusions show that salinities remain within the range of 5 to 15 equivalent weight percent nacl although homogenization temperatures fluctuate between 100 degrees and 500 degrees c evidence for boiling between 450 degrees and 223 degrees c indicates that the homogenization temperatures are trapping temperatures at low pressures between 65 and 650 bars some 18 o depletion in the aqueous fluids owing to unmixing and loss of co 2 in the fluorite veins delta 18 o quartz is approximately 14 per mil and calculated fluid delta values are 10 per mil 450 degrees c to 6 per mil 120 degrees c waters released from low temperature magmatic fluids which underwent transient mixing with a cool low 18 o meteoric reservoir modified journal abstract

characteristics of the marine boundary layers during two lagrangian measurement periods 2 turbulence structure characteristics of turbulence mixing in remote marine boundary layers are analyzed using aircraft measurements from six flights during the two intensive lagrangian measurement periods of ace1 the southern hemisphere aerosol characterization experiment the six cases studied here represent a variety of boundary layer conditions in the region south of tasmania australia our study indicated that 1 lagrangian a la had stronger turbulence mixing and entrainment compared to lagrangian b lb due to greater shear generation of turbulence kinetic energy tke 2 strong mesoscale variation in boundary layer turbulence and thus turbulence mixing existed in the ace1 region during lb due to variations in sea surface temperature sst 3 stable thermal stratification in the boundary layer was found during the last flight of each lagrangian consequently tke decreased rapidly with height resulting in small or near zero entrainment rate in spite of strong shear forcing at the surface and in the boundary layer and 4 the buffer layer which lies above the boundary layer and below the main inversion had weak and intermittent turbulence mostly associated with cloud bands and cumulus evidence of entrainment was found in the buffer layer however it is difficult to quantify by flux measurements due to the weak and intermittent nature of the turbulence field

paleomagnetism of the deadman s bay diabase dikes from northeastern central newfoundland twenty six oriented samples were collected from six diabase dikes cutting the deadman s bay granite of northeastern central newfoundland for the purpose of paleomagnetic investigations the dikes probably form part of a general swarm of diabase dikes in this area of devonian age 40ar 39ar age of 370 10 ma stepwise thermal demagnetization of individual specimens followed by vector subtraction based on zijderveld plots revealed two characteristic magnetizations one a poorly grouped magnetization of 78 0 95 17 4 16 carried by multidomain magnetite and a better grouped magnetization of 4 0 95 10 0 42 residing in hematite a baked contact test of the host rock deadman s bay granite intruded by the diabase dikes revealed a steep well grouped magnetization which is not dissimilar to that carried by magnetite in the dikes the magnetization of the host rock seems to be well grouped irrespective of distance away from the dike thus making the contact test inconclusive

characteristics of the marine atmospheric boundary layer over the southern ocean in response to the synoptic forcing the characteristics of the marine atmospheric boundary layer mabl in relation to synoptic meteorology over the southern ocean are examined using upper air soundings and surface precipitation at macquarie island 54 62 s 158 85 e with a primary focus on the post cold frontal environment where large cloud and radiative biases are presented in a multitude of climate models thermodynamic profiles from the european centre for medium range weather forecasts era interim reanalyses are compared with the observations to evaluate their representation of the mabl characteristics observations confirm that boundary layer clouds over the southern ocean commonly reside within a shallow mabl under the influence of frequent midlatitude cyclones and fronts the evaluation of mabl height shows that for both observations and reanalysis the inversion is higher northward of the low center and under postcold front conditions under cold frontal passages however the main inversions are not well represented by era interim which is featured by an underestimate of the mabl height by 22 significant differences are found in the moisture profiles within the mabl between the observations and era interim soundings within the context of cold frontal passages the moisture in the era interim is found to be too confined to the surface layer which is consistent with the shallower mabl represented by the era interim analysis of the surface precipitation shows that era interim overestimates the amount of precipitation over macquarie island in the vicinity of cyclone cores but underestimates the precipitation not immediately associated with cold fronts leading to an overall underestimate of the annual precipitation by 11

autogenic incision backfilling cycles and lobe formation during the growth of alluvial fans with supercritical distributaries autogenic cycles of channelization terminal deposit formation channel backfilling and channel abandonment have been observed in the formation of fans and deltas in subcritical flow these terminal deposits are characterized as mouth bars that lead to flow bifurcation backwater and eventual channel backfilling similar although less well characterized cycles also take place on supercritical subaerial and submarine fans this study investigates the hydraulics and morphodynamics of autogenic incision and backfilling cycles associated with supercritical distributive channel flow in alluvial fans the research questions of the study are i how are supercritical autogenic cycles on alluvial fans different from the subcritical cycles ii what are the hydraulic and sediment transport characteristics at the various stages of autogenic feedback cycles and iii what role do the cycles play in the overall fan evolution these questions are investigated in the laboratory and emphasis is placed on measuring the hydraulic and topographic evolution of the systems during the cycles the cycles arise quasi periodically under constant water and sediment discharge periods of sheet like flow are competent to move sediment but not competent enough to carry the full imposed load the net result is preferential deposition near the inlet resulting in fan steepening and an increase in flow competency with time at a sediment supply to capacity ratio of the sheet like flow is unstable to small erosional events near the inlet resulting in the collapse of the distributed flow to a strong channelized state during channelization a graded supercritical fr 1 channel develops and transports eroded and fed sediment up to and through the fan front extending the fan initiating a lobe shaped deposit and reducing the local slope the slopes defined by a sheet like flow with and channelized flow with set the maximum and minimum slopes on the fan respectively once formed graded channels act as bypass conduits linking the inlet with the terminal deposit on average deposits are up to six channel depths in thickness and have volumes approximately five times that of the excavated channel the main distinctive characteristics of the supercritical cycles relate to how the flow interacts with the terminal deposit at the channel to deposit transition the flow undergoes a weak hydraulic jump resulting in rapid sedimentation dechannelization and lateral expansion of the flow and deposition of any remaining sediment on top of the channel fill and floodplain this process often caps the channel as the deposit propagates up channel erasing memory of the excavated channel