elastic wave velocity evolution of shales deformed under uppermost crustal conditions conventional triaxial tests were performed on a series of samples of tournemire shale along different orientations relative to bedding 0 90 experiments were carried out up to failure at increasing confining pressures ranging from 2 5 to 80 mpa and at strain rates ranging between 3 10 7s 1 and 3 10 5s 1 during each experiment p and s wave elastic velocities were continuously measured along many raypaths with different orientations with respect to bedding and maximum compressive stress this extensive velocity measurement set up allowed us to highlight the presence of plastic mechanisms such as mineral reorientation during deformation the evolution of elastic anisotropy was quantified using thomsen s parameters wich were directly inverted from measurement of elastic wave velocity brittle failure was preceded by a change in p wave anisotropy due to both crack growth and mineral re orientation anisotropy variations were largest for samples deformed perpendicular to bedding at the onset of rupture anisotropy reversal was observed at the highest confining pressures for samples deformed parallel to bedding the p wave anisotropy change is weaker

behavior of transversely isotropic shale observed in triaxial tests and brazilian disc tests abstract shale rock is widely distributed in nature and must be taken into account in some rock engineering applications in this research three kinds of experiments namely the conventional triaxial compression test reducing confining pressure test and brazilian test were conducted on a type of shale rock specimen with a horizontal bedding plane and a vertical bedding plane collected from lushan city jiangxi province china to further investigate the bedding effect on the mechanical properties of shale rock an acoustic emission ae monitoring system was used to study the fracture process under the conventional triaxial compression test whereas a digital image correlation dic system was employed to monitor the deformation of disk faces during the failure process under the brazilian test another key issue addressed in this research is the failure process and mechanism of shale specimens with horizontal and vertical bedding planes under the reducing confining pressure test the conventional triaxial compression test shows that the bedding plane could easily affect the elasticity modulus and failure pattern and the failure of the bedding plane can lead to stronger energy release and a higher ae count level the reducing confining pressure test shows that the dissipated energy magnitude of unloading path ii reducing confining pressure and increasing axial stress is much larger than that of unloading path i reducing confining pressure and keeping axial strain constant and that continuous energy input and larger energy dissipation led the specimens under unloading path ii to fail faster than those under unloading path i the brazilian test further revealed that the bedding plane has a significant effect on the tensile strength and failure pattern of shale rock

geochemistry of surface sediments in the southwestern east japan sea abstract we analyzed 77 surface sediment samples collected in the southwestern east japan sea from the korea strait through the ulleung basin and the korea plateau for grain size calcium carbonate organic carbon and major na mg al fe k ca and ti and trace elements p mn sr li sc v cr co ni zn cu and pb the chemical composition of the surface sediments was found to be highly variable spatially cluster analysis of surface sediment chemical compositions indicated five major geochemical sedimentary environments basin lower slope coast and upper slope inner shelf and outer shelf continental shelf sediments were rich in shell fragments and had relict and coarse grained characteristics recent fine grained sediments were only distributed in coastal slope and basin areas concentrations of al k ca ti cr and sc were highest in the coastal and upper slope areas and decreased with water depth elemental ratios using major and trace elements indicated that coastal and upper slope detrital sediments were mixtures of sediments derived from the changjiang yangtze and nakdong rivers although the concentrations of organic carbon p mn v co ni cu and pb increased with water depth their distribution patterns indicated authigenic v cu and pb and diagenetic fe p mn co and ni origins the distribution pattern with water depth suggested that the chemical composition of surface sediment was determined by sedimentologic and geochemical processes such as the supply of detrital and biogenic materials and authigenic and post depositional diagenetic processes in sediments

recent upward shift of the deep convection system in the japan sea as inferred from the geochemical tracers tritium oxygen and nutrients the thermohaline circulation system in the japan sea an almost land locked marginal sea in the northwest pacific is now in a transition state comparison of vertical profiles of tritium oxygen and nutrients between 1984 and 1998 demonstrates the following two points 1 the supply of dense surface seawater to the bottom layer 2 500 m in depth has almost ceased since 1984 and 2 the intrusion of surface seawater to an intermediate depth range between 700 m and 2 000 m in depth has been reinforced during this 14 year period such transitional upward shift of the thermohaline conveyor belt in the japan sea is thought to have separeted the bottom water from the conveyor belt and brought about a stagnant mode of the bottom water

abyssal water mass exchange between the japan and yamato basins in the japan sea 1 bottom water exchange between the japan and yamato basins in the abyssal japan sea is investigated based on data from two research cruises in june 2010 and june 2011 distributions of water properties and velocity profiles from ctd ladcp observations revealed a two layer water mass exchange in a rotating system the cold japan basin bottom water jbbw with high dissolved oxygen do concentrations flowed into the yamato basin along the northern boundary of the channel connecting the basins while the warmer lower do yamato basin bottom water ybbw extended over the jbbw along the southern periphery of the channel a benthic front between the jbbw and ybbw was observed in both cruises though the front shifted to the northeast in 2011 compared with its 2010 location further the bottom flows in the channel were not unidirectional in 2011 though consistent southwestward flows were observed in 2010 the jbbw transport into the yamato basin was also larger in 2010 than in 2011 analysis of historical hydrographic data showed that the benthic front exists mostly in the narrowest region of the channel though it fluctuates temporarily to the northeast or southwest the fluctuation of the benthic front appears to be associated with the jbbw transport because the observations in june 2010 and june 2011 were carried out during periods of southwestward extension of cold water and northeast protrusion of warm water respectively a relationship between benthic front displacements and mesoscale warm eddy migrations is suggested

a moving boundary box model mbbm for oceans in change an application to the east japan sea 1 the east japan sea has undergone dramatic changes during the last 50 60 years as the result of a shift in its ventilation system from bottom water formation to intermediate water formation a moving boundary box model mbbm was developed to quantify these changes the model consists of three boxes for deep waters representing central deep and bottom waters respectively and two boundaries in between which are moving according to the volume changes of these water masses the model calibrated with cfc 11 and tritium distribution shows the bottom water formation of 0 02 sv in magnitude in the past slowed down and came to a complete halt in mid 1980s and late 1990s furthermore this model predicts the bottom water will disappear completely in 2040 as central water penetrates deeper considering the recent observations that many oceans are in change a mbbm could be a valuable tool to investigate the nature of such changes

global warming may have slowed down the deep conveyor belt of a marginal sea of the northwestern pacific japan sea weakening of the abyssal circulation conveyor belt in the japan sea during the 20th century is deduced from the decreasing trend of bottom dissolved oxygen o2 this trend indicates a shortened o2 supply caused by too inactive conveyor belt to compensate for biological o2 consumption at the bottom of the sea recent climatic changes during the winter season in the northern japan sea may play a significant role in prohibiting the formation of surface seawater dense enough to sink to the bottom it is predicted that the japan sea bottom water will become anoxic within a few hundred years as it was in the last glacial maximum

investigation of the damage induced by desiccation and heating of tournemire argillite using digital image correlation abstract a set of samples taken from the tournemire site was submitted to a desaturation process in an oven at different temperature levels of 40 c 50 c 80 c 105 c 150 c and 200 c the resulting hydro mechanical behavior was studied by measuring the strain fields obtained from a non invasive method called digital image correlation dic after a few dozens of minutes from the beginning of the thermal loading the induced strains concentrated into narrow zones or bands indicating strain localization these narrow zones were precursors of desiccation cracks which were also detected from the first temperature level at 40 c or 50 c our results confirmed the fundamental role of the textural and sedimentological heterogeneities in the cracking process desiccation cracks appeared at the interface between clay matrix and macroscopic non clayey heterogeneity i e calcite concretion and were predominantly parallel to the bedding planes at a temperature level of 105 c the desiccation cracks were no longer observable and seemed to close this healing process was interpreted as a thermally driven process when the shrinkage limit was reached a thermal dilation of the water clay minerals system occurred leading to a gradual closure of desiccation cracks

temperature trends over the past five centuries reconstructed from borehole temperatures for an accurate assessment of the relative roles of natural variability and anthropogenic influence in the earth s climate reconstructions of past temperatures from the pre industrial as well as the industrial period are essential but instrumental records are typically available for no more than the past 150 years therefore reconstructions of pre industrial climate rely principally on traditional climate proxy records each with particular strengths and limitations in representing climatic variability subsurface temperatures comprise an independent archive of past surface temperature changes that is complementary to both the instrumental record and the climate proxies here we use present day temperatures in 616 boreholes from all continents except antarctica to reconstruct century long trends in temperatures over the past 500 years at global hemispheric and continental scales the results confirm the unusual warming of the twentieth century revealed by the instrumental record but suggest that the cumulative change over the past five centuries amounts to about 1 k exceeding recent estimates from conventional climate proxies the strength of temperature reconstructions from boreholes lies in the detection of long term trends complementary to conventional climate proxies but to obtain a complete picture of past warming the differences between the approaches need to be investigated in detail

effects of relative humidity and mineral compositions on creep deformation and failure of a claystone under compression abstract during the last decades clayey rocks have been widely investigated in many countries as a potential geological barrier for underground disposal of radioactive waste clayey rocks are heterogeneous materials at a micrometer scale mechanical behaviors of clayey rocks are generally influenced by mineralogical compositions and or water content a large number of studies have been so far performed on short term behaviors of clayey rocks however very limited data are available on time dependent deformation and failure process this paper is devoted to investigating the effects of relative humidity and mineralogical compositions on creep deformation of a hard claystone and the possibility of creep failure is studied influences of confining pressure and structural anisotropy are also investigated for this purpose four groups of creep tests are carried out under triaxial compression conditions on claystone samples drilled from the underground research laboratory at bure in france in the first group creep tests are performed on samples with three different values of relative humidity rh 59 85 and 98 under a confining stress of 6 mpa in the second group claystone samples with different mineralogical compositions drilled from different geological unities are investigated in the third group for a selected value of relative humidity rh 59 triaxial creep tests are performed under different values of confining stress 2 6 and 12 mpa finally effects of structural anisotropy of claystone at hr 59 are investigated by considering samples respectively drilled in parallel and perpendicular directions to the bedding planes a series of new experimental data are obtained and analyzed it is found that at the tested level of relative humidity the confining stress seems to increase creep strain and rate of the claystone the clay minerals especially the smectite can play an essential role in time dependent deformation and increase creep strain of the claystone at rh 59 further creep strains are more important under higher values of relative humidity than lower ones in very few cases the failure due to acceleration creep was observed but for high deviatoric stress level the experimental data obtained in this work can be used as a background for numerical modeling of time dependent behavior of re desaturated clayey rocks in the context of geological disposal of radioactive waste

in situ x ray micro ct for investigation of damage evolution in black shale under uniaxial compression crack damage evolution of shale is crucial to the hydraulic fracturing treatment and engineering stability although many effects have been done on the macroscopic characteristics of shale yet the microscopic failure mechanism is not well understood a uniaxial compressive test on black shale was conducted under topographic monitoring using in situ x ray micro tomography ct a series of high resolution reconstruction images were obtained by carrying out ct scans at six key points throughout the test to obtain the internal structure of shale sample in addition the ct values for the purpose of crack damage evolution in shale were identified clear 2d 3d ct images ct value analysis and image segmentation analysis reveal that the sample experiences compression damage cracking crack propagation and collapse stages crack geometry and distribution in the shale sample is visualized by rendered ct images and a combined tension and shear failure mode is observed from the fracture rose diagram this work suggests that formation and propagation of fractures are influenced by the stratified structure and weak cementation medium between layers

an enhanced understanding of the basinal bowland shale in lancashire uk through microtextural and mineralogical observations abstract variability in the lower bowland shale microstructure is investigated here for the first time from the centimetre to the micrometre scale using optical and scanning electron microscopy om sem x ray diffraction xrd and total organic carbon content toc measurements a significant range of microtextures organic matter particles and fracture styles was observed in rocks of the lower bowland shale together with the underlying pendleside limestone and worston shale formations encountered the preese hall 1 borehole lancashire uk four micro texture types were identified unlaminated quartz rich mudstone interlaminated quartz and pyrite rich mudstone laminated quartz and pyrite rich mudstone and weakly interlaminated calcite rich mudstone organic matter particles are classified into four types depending on their size shape and location multi micrometre particles with and without macropores micrometre size particles in cement and between clay minerals multi micrometre layers and organic matter in large pores fractures are categorized into carbonate sealed fractures bitumen bearing fractures resin filled fractures and empty fractures we propose that during thermal maturation horizontal bitumen fractures were formed by overpressuring stress relaxation compaction and erosional offloading whereas vertical bitumen bearing resin filled and empty fractures may have been influenced by weak vertical joints generated during the previous period of veining for the majority of samples the high toc 2 wt low clay content 50 wt and the presence of a multi scale fracture network support the increasing interest in the bowland shale as a potentially exploitable oil and gas source the microtextural observations made in this study highlight preliminary evidence of fluid passage or circulation in the bowland shale sequence during burial

climate change record in subsurface temperatures a global perspective analyses of underground temperature measurements from 358 boreholes in eastern north america central europe southern africa and australia indicate that in the 20th century the average surface temperature of earth has increased by about 0 5 degreesc and that the 20th century has been the warmest of the past five centuries the subsurface temperatures also indicate that earth s mean surface temperature has increased by about 1 0 degreesc over the past five centuries the geothermal data offer an independent confirmation of the unusual character of 20th century climate that has emerged from recent multiproxy studies

the effects of geothermal heating on the east japan sea circulation 1 the magnitude of geothermal heating in the east japan sea is about 100 mw m2 twice that of a typical abyssal plain in addition bottom stratification in the east japan sea is much weaker than that typical of the open ocean thus geothermal heating could have more prominent effects in the east japan sea than in the open ocean and we tested this hypothesis via numerical modeling with less than 100 mw m2 bottom heat flux we were able to reproduce bottom mixed layers that are thicker than 1000 m as observed previously no numerical model has been successful in reproducing such bottom mixed layers geothermal heating intensifies the bottom flows but the simulated flows are not as strong as the observed ones over the northern part of the east japan sea reduction in deep stratification strengthens deep water mass formation intensifying cyclonic circulations located over this area so the effects of the heating extend to the surface as the cyclonic circulation becomes stronger the water at the center of the gyre is trapped and more exposed to cold air so it becomes cooler and colder deep water is produced when the geothermal heating is strong enough the surface cooling effect dominates the bottom heating and the deep layer becomes cooler showing that the nonlinear effects of geothermal heating are far reaching thus to account for the observed dynamics the full three dimensional circulation at the basin scale is needed

iron in the japan sea and its implications for the physical processes in deep water 1 labile dissolved fe dfe 0 22 m fraction and total dissolvable fe tdfe unfiltered were examined throughout the water column of the northeastern japan basin and mid eastern yamato basin basin regions in the japan sea we observed extremely high vertically integrated tdfe inventories and low nutrient concentrations at the surface water in both basins probably resulting from high atmospheric fe input to nutrient depleted surface water dfe in both basins was characterized by mid depth maxima and below that a slight decrease with depth in deep water and uniform concentration in bottom water in the japan basin surprisingly tdfe concentrations in bottom water were lower than those in deep water resulting from the injection of new bottom water on the contrary tdfe concentrations in bottom water of the yamato basin increased gradually with depth and were higher than those in deep water probably due to the supply of iron during the horizontal transport of the bottom water in the japan basin towards the yamato basin the tdfe with a high percentage of labile particulate fe tdfe minus dfe may have important implications for understanding the physical processes of bottom water in the japan sea

possible source of advected water mass and residence times in the multi structured sea of japan using rare earth elements 1 the sea of japan is a small fast acting model of global oceanic circulation observations from 1998 and 2001 are analyzed to clarify its circulation new bottom water formed in early 2001 off vladivostok was observed later that year near the southeastern edge of the japan basin implying a velocity of 2 3 3 9 cm s 1 tb yb patterns of rare earth elements distinguish two classes of water volume inactive old well mixed water and active relatively young water frequently affected by the subduction of the surface water originating from tsushima warm current twc the proportion of twc to old water and each residence time are 50 75 and 15 years 200 400 m and 35 80 and 38 years 600 1500 m using six strata an improved estimate of the average residence time of japan sea proper water is 86 years this includes the contributions from active and inactive strata

strength anisotropy of shales deformed under uppermost crustal conditions conventional triaxial tests were performed on three sets of samples of tournemire shale along different orientations relative to bedding 0 45 90 experiments were carried out up to failure at increasing confining pressures ranging from 2 5 to 160 mpa at strain rates ranging between 3 10 7s 1 and 3 10 5s 1 this allowed us to determine the entire anisotropic elastic compliance matrix as a function of confining pressure results show that the orientation of principal stress relative to bedding plays an important role on the brittle strength with 45 orientation being the weakest we fit our results with a wing crack micromechanical model ashby and sammis 1990 and an anisotropic fracture toughness we found low values of internal friction coefficient and apparent friction coefficient in agreement with friction coefficient of clay minerals between 0 2 and 0 3 and values of kic comparable to that already published in the litterature we also showed that strain rate has a strong impact on peak stress and that dilatancy appears right before failure and hence highlighting the importance of plasticity mechanisms although brittle failure was systematically observed stress drops and associated slips were slow and deformation always remained aseismic no acoustic emission were detected this confirms that shales are good lithological candidates for shallow crust aseismic creep and slow slip events

inference of ground surface temperature history from subsurface temperature data interpreting ensembles of borehole logs ground surface temperature histories gsths inferred from borehole temperaturedepth t z data are often degraded to a various extent by random or systematic noise in thet z data and in the measurements of thermophysical properties of the earth to minimize the effects of noise and hence improve the fidelity of the inferred gsth a plausible approach is to perform a simultaneous inversion of thet z logs in a region or alternatively to invert the individualt z logs and then average the resulting gsths averaging and simultaneous inversion are conceptually different whereas an averaging can always be peformed a simultaneous inversion is predicated on the assumption of a common transient component of the gsth in all thet z logs in this work we examine and compare the two approaches using a time domain inverse formulation based on the method of least squares we consider a set of scenarios a multiplet z logs from a single borehole b multiple boreholes from a single site c multiple boreholes in similar climatological settings and d multiple boreholes in different climatological settings we show that for a b and c averaging and simultaneous inversion yield nearly identical results for boreholes in different settings the assumption of a common transient gsth may be invalid and averaging and simultaneous inversion give divergent results

deep flow field in the japan east sea as deduced from direct current measurements abstract the mean flows and variability in the abyssal japan east sea are investigated on the basis of direct current observation data the distribution of the mean flow vectors indicates relatively strong cyclonic circulations along the basin periphery and sluggish flows in the interior region strong mean flows of faster than 6 0 cm s 1 are found at the western edge in the yamato and ulleung basins considered to be the western boundary currents in each basin the similarity between the distributions of the mean flow vectors in the upper 400 1000 m and lower layers 1000 m bottom indicates common circulation patterns throughout the water column of the proper water progressive vector diagrams show meandering curves with clockwise and anticlockwise turns due to the passing of mesoscale eddies since a dominant background flow is absent in the basin interior the ratio of eddy kinetic energy to the mean flow kinetic energy reaches more than 50 in the interior region this indicates that the flows observed in the interior region are comparable to those in the basin periphery even though the mean flow is generally weak spectral analysis has revealed that tidal fluctuations are prevailing in the ulleung basin while they are absent in the yamato and japan basins though the inertial oscillation is dominant in all of the basins this indicates that the tidal energy from the east china sea is confined within the ulleung basin suggesting the barrier effect of the yamato rise and the oki spur significant energy peaks are also found in the 2 5 and 5 10 day period bands in the yamato basin the former variation represents the shelf wave activity trapped on the basin edge and the latter is due to eddy migrations associated with the tsushima current

drastic hydrographic changes inferred from radiolarian assemblages in the central japan sea since the last glacial maximum abstract assessing modern radiolarian distribution in the marginal seas is essential for understanding its relationship to hydrographic and environmental variables upon which subsequent interpretation of past radiolarian records can be made reliably here we combine published radiolarian assemblages in 69 surface sediments from the japan sea with those obtained from 15 new surface sediments in this study to determine the modern distribution of radiolarians the tsushima warm current twc taxa are only found in the south of the subpolar front the results of redundancy analysis confirm that the temperature at 10 m depth temperature10m is the main factor controlling the spatial variability of twc taxa the water depth plays a key role in affecting the abundances of japan sea proper water jspw assemblage including larcopyle buetschlii dreyer adult cycladophora davisiana ehrenberg and actinomma group the jspw assemblage can be used as a reliable indicator of ventilation changes in the japan sea based on the newly developed twc taxa and jspw assemblage we further reconstructed the water column structure in the central japan sea over the past 25 ka there was weak ventilation in the central japan sea even during the last glacial maximum lgm although a distinct decrease in the twc inflow resulted in surface water freshening and water column stratification after the lgm the twc taxa together with jspw assemblage resumed in the central japan sea at the 19 ka meltwater pulse mwp the mwp 1a was clearly marked by an enhanced intrusion of the twc synchronously jspw was ventilated deeply down after 14 6 ka attaining to the similar level of the holocene as a result of changing sea surface conditions along with the continuing sea level rise the matured twc entered the japan sea at 7 ka and since then the modern hydrographic condition has been established we suggest that the changes in the sea level and twc strength predominantly determined the surface hydrography and deep ventilation in the central japan sea since 25 ka and the twc might have notably affected the japan sea since the bolling allerod

trace of the recent deep water formation in the japan sea deduced from historical 137cs data historical 137cs data obtained in the japan sea were statistically analyzed 137cs concentrations in the upper 200 m layer decreased almost monotonously after 1970 s while those in the deeper layers below 1500 m depth sharply increased during the period of 1985 1995 accompanied with the increase of the 137cs inventory it follows that considerable amount of 137cs rich surface water was conveyed into the deep layers after 1985 suggesting that the deep water formation occurred the spatial distribution of 137cs in the deep layers in 1990 s indicates that the recent deep water formation occurred in the northwestern area of the japan sea around peter the great bay

low frequency temperature variations from a northern tree ring density network we describe new reconstructions of northern extratropical summer temperatures for nine subcontinental scale regions and a composite series representing quasi northern hemisphere temperature change over the last 600 years these series are based on tree ring density data that have been processed using a novel statistical technique age band decomposition designed to preserve greater long timescale variability than in previous analyses we provide time dependent and timescale dependent uncertainty estimates for all of the reconstructions the new regional estimates are generally cooler in almost all precalibration periods compared to estimates obtained using earlier processing methods particularly during the 17th century one exception is the reconstruction for northern siberia where 15th century summers are now estimated to be warmer than those observed in the 20th century in producing a new northern hemisphere series we demonstrate the sensitivity of the results to the methodology used once the number of regions with data and the reliability of each regional series begins to decrease we compare our new hemisphere series to other published large regional temperature histories most of which lie within the 1 confidence band of our estimates over most of the last 600 years the 20th century is clearly shown by all of the palaeoseries composites to be the warmest during this period

excess 222rn profiles in the bottom layer of the japan sea and their implication for bottom water dynamics abstract vertical profiles of excess radon 222 222 rn half life 3 82 days in bottom seawaters between 8 and 780 m above the seafloor were measured in the japan sea a semi closed deep marginal sea in the northwest pacific ocean all of the profiles observed at three locations two profiles in the japan basin and one in the yamato basin show curious zigzag patterns with 222 rn maxima and minima in contrast to a generally known steady state profile of 222 rn exponentially decreasing with the distance above the bottom the observed 222 rn profiles demonstrate the existence of horizontal supplies of 222 rn enriched waters in the bottom layer of the japan sea with timescales as short as the half life of 222 rn probably in relation with the interaction between bottom currents and topographic features

experimental investigation of the effect of temperature on the mechanical behavior of tournemire shale this paper is devoted to the experimental investigation of the effect of temperature on the mechanical behavior of a typical anisotropic clayey rock the tournemire shale hydrostatic and conventional triaxial compression tests are first performed under room temperature for two principal loading orientations respectively parallel and perpendicular to the bedding planes the obtained results confirm an anisotropic mechanical behavior observed by the previous works further hydrostatic and triaxial compression tests with different confining pressures are carried out under different temperatures up to 250 c with the increase of temperature there is a significant decrease of young s modulus and the compression failure strength but an increase of the overall deformability of material the temperature change also affects the anisotropic response related to the deformation of bedding planes

east to west retardation in the onset of the recent warming across canada inferred from inversions of temperature logs 1 canadian well temperature logs for 141 sites are analyzed and show evidence of extensive ground surface temperature gst warming beginning in the eighteenth and nineteenth centuries following a lengthy period of cooling the little ice age over most of the past millennium the method of functional space inversion fsi is applied to the complete set of 141 well precise temperature logs from wells located in low conductivity clastic sediments of the western canadian sedimentary basin and higher thermal conductivity crystalline rocks of the canadian shield in central and eastern canada marked regional differences in the onset of recent warming are evident nineteenth century compared to the seventeenth to eighteenth centuries respectively following a prolonged cold period through earlier centuries analysis of spatial patterns of gst history changes across canada based on the individual inversions of temperature logs shows a systematic east to west retardation in the onset of the recent warming yet a higher overall warming magnitude in western canada in the twentieth century

decadal changes in meridional overturning circulation in the east sea sea of japan abstractmeridional overturning circulation moc is vital to distributing heat freshwater and dissolved matter in semi enclosed deep marginal seas such as the east sea es as our understanding

sensitivity of simulated circulation dynamics to the choice of surface wind forcing in the japan east sea abstract the circulation sensitivity to the choice of wind forcing product is investigated with the nrl layered ocean model nlom configured for the japan east sea monthly climatologies from seven different wind stress data sets and wind stress curl are formed from observed and model derived atmospheric data sets the resulting maps of wind stress curl reveal significantly different spatial patterns and magnitudes even two with largely opposite large scale patterns of wind stress curl these wind sets were used in forcing three sets of simulations 1 8 linear and 1 8 and 1 32 nonlinear in addition seasonally varying straits forcing inflow through tsushima balanced by outflow through tsugaru and soya was included in all the simulations and simulations with straits forcing only were performed the 1 5 layer linear reduced gravity simulations include only the lowest order dynamics mainly munk 1 3 western boundary layers due to both wind and straits forcing and a sverdrup interior the nonlinear simulations add bottom topography multiple internal modes diapycnal mixing and ventilation of layer interfaces at 1 8 resolution only weak barotropic baroclinic instabilities occur but at 1 32 resolution these are much stronger allowing vigorous transfer of energy from the upper ocean to the abyssal layer via baroclinic instability this drives much stronger mean abyssal currents that more strongly steer upper ocean current pathways than at 1 8 i e there is much stronger upper ocean topographical coupling the linear model simulates most of the basic features e g the subpolar gyre with all but the straits forcing only the east korean warm current ekwc and its connection to the subpolar front with all but one wind forcing set but the remaining wind set gives a continuous nearshore branch nb of the tsushima warm current along the coast of honshu in all of the linear simulations with an ekwc the separation latitude from the coast of korea is determined by the latitude 41 n of the tsugaru strait outflow too far north except for one which is also too far north all of the nonlinear simulations include the nb which is mainly due to isopycnal outcropping this creates another inflow to outflow pathway diverting some of the flow from the ekwc and allowing the wind stress curl to compete better with straits forcing in determining the ekwc separation latitude using the 1 8 nonlinear model three of the wind forcing sets yield a realistic separation latitude for the ekwc 37 38 n and two more are marginally successful the two remaining and the simulation with straits forcing only yield ekwc overshoot to 40 n at 1 32 resolution one of the simulations one with forcing that gave marginally realistic separation at 1 8 has a realistic ekwc separation latitude the three wind products that yielded realistic ekwc separation at 1 8 continue to give realistic separation at 1 32 via the wind stress curl but the remainder give realistic separation via upper ocean topographical coupling at 1 32 resolution all but one of the simulations showed a strong yamato rise impact on the pathway of the subpolar front due to steering by abyssal currents at 1 8 resolution only two of the eight showed any such impact one due to abyssal currents driven by vertical mixing in the subpolar gyre in all the other 1 8 simulations the mean abyssal currents were weak but in one case weak abyssal currents were aided by a region of strong negative wind stress curl not seen in the other wind products in addition regions of the ventilation of intermediate and deep water in response to each wind set are identified a series of six 1 32 simulations forced interannually with 6 hourly winds 1979 93 are used to separate the model variability due to wind forcing deterministic and flow instabilities nondeterministic this analysis indicates that flow instabilities are the dominant source of ssh variability over a large majority of the basin especially near 37 38 n where the ekwc separates from the coast and along the pathway of the subpolar front following the north rim of the yamato rise towards the tsugaru strait wind forcing dominates the ssh variability in the coastal wave guide and over the deep basins and troughs

a geothermal climate change observatory first year results from emigrant pass in northwest utah temperature depth profiles measured in boreholes contain a temporal record of past changes in surface ground temperature and provide valuable constraints on climatic variations over the last few centuries however the linkage between ground temperature and meteorological variables including air temperature is imperfectly known to understand that linkage better and to document in detail how the surface ground temperature changes propagate into the subsurface where they are later measured in temperature depth logs in boreholes we have designed and installed a geothermal climate change observatory installed in arid northwest utah our emigrant pass observatory epo consists of an array of thermistor strings in the subsurface and a meteorological station at the borehole collar results from our first complete annual cycle november 1 1993 though october 31 1994 are presented ground and air temperatures generally track each other but with important time varying offsets the mean surface ground temperatures for the period are 11 3 c on the granite outcrop and 9 5 c for the partially shaded regolith site mean air temperature at a 2 m mast height above the ground is 8 8 c the ground air temperature differences are variable on timescales from days to seasons largely governed by level of absorbed solar radiation marginal precipitation 8 6 mm and ephemeral snow cover did not significantly disturb the ground air temperature difference during the year monitored instrumental measurement of air temperature has nonrandom sampling biases that present problems for observing long term changes the calculation of average annual air temperature at epo decreases by 0 34 k as the sampling rate of air temperature is decreased from 60 s to every 12 hours the attenuation and phase lag of thermal waves with depth confirm that heat conduction theory adequately describes the transient temperature field at this site and yield in situ estimates of thermal diffusivity a quantity needed to reconstruct surface ground temperature histories thermal diffusivity for the granite and regolith is 0 88 10 6 m2 s 1 and 0 45 10 6 m2 s 1 respectively energy flux calculations for the emigrant pass observatory site suggest that a geothermal climate change observatory has the capability of detecting a century scale energy perturbation that is one part in a million of the instantaneous flux

effects of subsurface heterogeneity on the inference of climate change from borehole temperature data model studies and field examples from canada all existing approaches to the analysis and interpretation of borehole temperatures in terms of a ground surface temperature history are based on the one dimensional theory of heat conduction deviations from this idealization are manifest as noise in the interpretation we present numerical experiments that explore the effects of three dimensional subsurface heterogeneity on ground surface temperature histories inferred from borehole temperature profiles inversions of steady state temperature profiles containing such three dimensional noise reveal that in an inversion formulation incorporating a priori information spurious temperature histories can emerge when the a priori constraints on subsurface temperatures and thermophysical properties are too tight i e when arbitrarily small variations in subsurface temperatures and thermophysical properties are interpreted to have significance for the derived climate history relaxation of the a priori constraints enables an effective muting of the spurious histories similar experiments conducted on synthetic transient signals confirm the steady state results but also reveal that relaxation of the a priori constraints will also lead to a loss of signal if the level of relaxation is excessive our experiments suggest that relaxation of constraints on thermal conductivity is more efficient than relaxation of borehole temperatures in suppressing artifacts arising from the three dimensional effects we identify a range of constraints in which reasonable noise suppression and signal recovery are both achieved and then reprocess data from 22 canadian boreholes for which surface temperature histories had earlier been derived by ourselves and others our reprocessed results reveal a remarkably simple surface temperature history common to much of eastern canada this history comprises a recent warming interval commencing in the nineteenth century in which the surface temperature increased by some 1 4 c approximately 0 5 1 0 c of this increase was a recovery from a preceding cooler interval in which the temperature was below the long term mean the remainder of the increase represents warming that exceeds the long term mean

estimation of ground surface temperatures from borehole temperature data to infer past climatic changes from temperatures measured in boreholes one must obtain reliable estimates of ground surface temperature gst histories from these data this paper presents a method that uses a bayesian inverse technique to estimate the gst in the fourier frequency domain by assuming the a priori gst to be stationary with a prescribed standard deviation and a cutoff period the time series is constrained to be bounded and smooth because accounting for conductivity variations with depth is crucial to the estimation of gst a layered earth medium has been used for which the forward analytical solution of one dimensional heat conduction is available borehole data from flin flon and lac dufault in canada are inverted with this method the flin flon hole logged to a depth of 2900 m provides an opportunity to study long term gst variations and the estimated gst from this hole shows some effects of deglaciation at the end of pleistocene at lac dufault similar gsts were obtained independently from three holes ranging from 550 to 900 m and hence the results are considered more reliable in the lac dufault gsts there is a warm period centered about 1000 years bp and a cold period about 400 years b p confirming the presence of the little climatic optimum and the little ice age respectively the flin flon result does not show the little climatic optimum and the little ice age occurs about 100 200 years earlier however in both locations the gsts show another brief cold period around the turn of the century followed by rapid warming until 1940 1950 in good agreement with the trend of northern hemisphere surface air temperatures

thermomechanical properties of deep argillaceous formations abstract a difficulty in the interpretation of mechanical and thermo mechanical tests on specimens drawn from large argillaceous formations is the strong inhomogeneity of void ratio clay minerals and carbonates content in this paper a relationship is developed to link strength and the maximum preconsolidation stress to the initial void ratio and carbonate content compressibility is also correlated to carbonates thermal strains in drained and undrained conditions for a spanish a belgian and an italian natural clay are compared in the elastic state strains are comparable while in the plastic range thermal strains are highest for the belgian clay lower in the spanish cemented clay and lowest in the italian clay very stiff and cemented

large regional variability of recent climatic change driven sub surface temperature changes as derived from temperature logs central canada example the analysis of the warming cooling patterns from inversion of 94 well temperature logs for the study area of central canada shows very high variability 1 to 3 c analysis of the warming cooling patterns in last 2 3 centuries indicates that warming has not affected the whole study area and some surface areas have significantly cooled regions of large cooling as well as regions of large warming are apparent largest cooling is observed in the ne part of the study area while large warming is observed in the area south east of it in a ridge running nw se slightly north of great lakes these patterns go against patterns of land development which is an unlikely factor forcing these regional scale changes derived mainly from the well sites chosen to be in remote and forested areas

deep currents obtained from argo float trajectories in the japan east sea abstract the deep currents at 700 800 m depths from argo float trajectories including pre argo floats have been compiled from 1999 to 2010 in the japan east sea jes more than 14 000 velocities from the dataset provides the first view of interbasin scale dependency in deep currents of the jes such as mean circulation and eddy variability especially with an emphasis on their topographic steering characteristics the observational findings in this study are 1 the argo observation exhibits dominance of cyclonic mean circulation in the entire jes yet with a distinct interbasin variability of its magnitude the mean circulation is strongest in the eastern japan basin jb while overall currents in the ulleung basin ub are weaker than that in the eastern japan basin and western yamato basin yb by a factor of two to three 2 the eddy kinetic energy eke is maximum in the western japan basin where strong dipole structure of wind stress curl in winter is located the interior of each basin the eastern jb ub and yb has local maxima of the eke a factor of four to five smaller than that in the western jb 3 cyclonic bottom following characteristics prevail in the bin averaged velocities however the individual deep flows presumably containing temporal variability have a preference to follow topography not only with cyclonic flows shallow depth to the right but also anticyclonic flows shallow depth to the left especially when flows are highly energetic occurrence of anticyclonic flows is proportional to the local eke level relative to mean kinetic energy implying that such flows could exist only in a transient manner such as topographic rossby waves the argo observations may demonstrate an asymmetry of stable cyclonic and unstable anticyclonic circulation in the marginal seas of the northern hemisphere as the previous theoretical modeling studies suggested

observing global ocean topostrophy 1 recent publications have evaluated topostrophy f v d where is f coriolis v is velocity and d is gradient of total depth as a means of comparing models circulations some results are striking comparing four global models two with modest grid size and two with fine grids merryfield and scott 2007 show that finer grid models are characterized by more positive especially at greater depths and higher latitudes among nine arctic ocean models holloway et al 2007 find in three of the models quite distinct from the other six a result shown to depend upon subgrid eddy parameterization from different choices of numerical method within the same model penduff et al 2007 show that improved numerical representations support more positive can these model results be compared with observations a global compilation has been prepared from 17120 current meter records spanning 83087 current meter months the compilation tends to confirm modeling progress achieved by finer resolution improved parameterizations and better representations a new characterization of global ocean circulation emerges with suggestive dynamical insights