shear wave splitting and subcontinental mantle deformation splitting observations are interpreted in terms of the strain induced lattice preferred orientation of mantle minerals especially olivine we consider three hypotheses concerning the origin of the continental anlsotropy 1 strain associated with absolute plate motion as in the oceanic upper mantle 2 crustal stress and 3 the past and present internal deformation of the subcontinental upper mantle by tectonic episodes it is found that the last hypothesis is the most successful namely that the most recent significant episode of internal deformation appears to be the best predictor of q for stable continental regions this is interpreted as fossil anisotropy whereas for presently active regions such as alaska the anisotropy reflects present day tectonic activity in the stable portion of north america there is a good correlation between delay time and lithospheric thickness this is consistent with the anisotropy being localized in the subcontinental lithosphere and suggests that intrinsic anisotropy is approximately constant the acceptance of this hypothesis has several implications for subcontinental mantle deformation first it argues for coherent deformation of the continental lithosphere crust and mantle during orogenies this implies that the anisotropic portion of the lithosphere was present since the deformational episode and rules out the addition of undeformed material to this layer by subsequent underplating or conductive growth of the thermal boundary layer one of the most important issues in the study of orogenies is the need to reconcile the formation of thickened lithosphere with the paradoxically high mantle temperatures often associated with orogenic episodes most efforts to date have focussed on modes of deformation whereby the cold lithospheric mantle is removed by convective instability or delamination and replaced by warm asthenosphere these models however are incompatible with the evidence for preserved coherent lithospheric deformation rather the deformed mantle appears to have been heated in place we suggest that the elevated mantle temperatures may be due to the strain heating accompanying the deformation

the hercynian crust in northwestern spain a seismic survey abstract in summer 1982 a network of crustal seismic profiles was established in nw spain with shotpoints at sea and on land some profiles were designed to capture the general features of the crust whereas others were aimed at resolving the detailed structure of specific geological features the interpretation of three profiles aimed at the most important features of the earth s crust in northwest spain is discussed here the crust consists of three layers with compressional velocities of 6 0 6 1 km s 6 2 6 3 km s and 6 7 6 9 km s the thicknesses of these layers vary laterally the average values under the central part of galicia being 13 km 8 km and 10 km the fine structure of the lower crust has still to be determined so far lateral variations in the velocity structure of the lower crust from a constant velocity layer to a gradient layer have been detected along the main profile from ne to sw over a distance of 250 km the moho discontinuity is reached at 30 32 km in the central part of the surveyed area this decreases to 23 27 km to the north and to the west on the basis of pmp amplitudes the moho seems to be rather sharp the pn velocity is close to 8 3 km s which is slightly above the normal value elsewhere in hercynian europe the crustal structure is remarkably similar to other hercynian domains particularly brittany the massif central and the central iberian massif

geomorphological and botanical change on the outer slave river delta nwt before and after impoundment of the peace river this paper examines geomorphological and botanical changes on the outer low elevation portion of the slave river delta prior to and after impoundment of the peace river at hudson s hope british columbia the slave river delta deposits are approximately 8300 km 2 about 5 400 km 2 is defined as the active delta which progrades into great slave lake through an active system of distributaries this active portion of the delta is the area studied the peace river provides approximately 65 of the annual flow of the slave river alteration of the natural flow regime and suspended sediment load of the slave river has resulted from the upstream impoundment calculations indicate that the annual suspended sediment load in the slave river has decreased by 33 using aerial photographs of the slave delta taken in 1946 and 1966 prior to damming the peace river geomorphological change and the spatial changes in plant assemblages have been recorded using gis software aerial photographs taken in 1977 and 1994 were used in similar fashion to document geomorphological and botanical change and rates of change after impoundment the outer delta is most susceptible to hydrological and suspended sediment changes in the river system as such it is shown that geomorphological development in these outer delta landforms has been notably reduced since impoundment and changes in plant assemblage distribution indicates a drier less productive environment results of aerial photo analysis show that the rate of development of distinctive cleavage bar islands on the outer delta has been notably reduced since impoundment changes in plant assemblage areas on these islands indicates both an autogenic and allogenic change to a drier less productive environment and actual loss by erosion of some of the most productive equisetum assemblages

a deep seismic sounding investigation of lithospheric heterogeneity and anisotropy beneath the iberian peninsula abstract the dimensions of the iberian peninsula the facility of firing large charges in the surrounding waters the well known and relatively uniform geology and prior knowledge of the crustal structure resulted in it being chosen as a study area for the investigation of the seismic structure of the lower lithosphere via refraction wide angle reflection seismic profiling the iberian lithosphere heterogeneity and anisotropy experiment iliha with a star shaped arrangement of six long range dss profiles was carried out in october 1989 the models derived from a first interpretation of the recorded data are presented three crustal profiles cover the same western and central part of the hercynian massif as the mantle profiles the resulting interpretations all include a middle as well as a lower crustal layer above the mantle the velocities of the layers in all three models are similar however the layer depths vary beneath the profiles interpretation of the mantle derived data suggests a layered lower lithosphere one reversed line and an intersecting unreversed line indicate the layering penetrates to at least 90 km depth the homogeneity of these layers contrasts strongly with the heterogeneous hercynian surface geology velocities derived from reflected data from the deep layers suggest the constituent materials are either anisotropic or that the layers suffer a slight regional dip

moment tensor solutions for small and moderate earthquakes in the ibero maghreb region 1 we applied time domain moment tensor inversion of local and regional waveforms to small and moderate mw 3 5 5 7 shallow earthquakes from the iberian peninsula northern morocco and northern algeria for the 6 years period from november 1995 to march 2002 and the previous network of autonomously recording seismograms nars experiment moment tensor solutions were obtained for 58 events considerably increasing the total number of available solutions in the study area for each event we performed a moment tensor inversion and a double couple grid search for simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation the computed mechanisms show regional consistency a large part of the iberian peninsula is characterized by normal faulting mechanisms with sw ne oriented t axes thrusting and se nw compression is dominant in algeria in the alboran sea the westernmost part of the mediterranean and the transition between both regimes strike slip mechanisms dominate with approximately n s oriented p axes this pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations

anticyclonic rings in the gulf of mexico abstract using the historical data set this study describes the anticyclonic rings that separated from the loop current in the eastern gulf of mexico six quasi synoptic data sets are used to describe the evolving circulation of the gulf of mexico from october 1966 to september 1967 showing the separation and movement into the western gulf of three anticyclonic rings the historical data are used to determine that these rings typically translate to the west at a mean speed of 2 1 km day 1 their length scale as defined by their rms radii is 183 km an estimate of ring life span as defined by an e folding time is one year within the context of the gulf s water property distributions these rings appear as warm salty bodies the heat and salt added by one of these rings after separation are estimated to be 7 109 j m 2 and 17 g cm 2 respectively the heat and salt added by one of these features play an important role in the heat and salt budget of the western gulf the latter indicates that about one r

can climate variations be inferred from tree ring parameters and stable isotopes from larix decidua juvenile effects budmoth outbreaks and divergence issue abstract larch wood has been used for centuries as a building material hence the study of the tree ring width the latewood maximal density and the oxygen and carbon isotope composition of the cellulose of this tree provides potential and valuable insights when reconstructing past climate variability we explore the qualities and limitations of these proxies focusing on a forest standing the nevache valley french alps the analysis of 15 trees demonstrates a small intra tree variability in comparison with the inter tree variability of 13c and 18o and shows that 6 trees at least must be pooled to make a population representative sample our results show no juvenile effect for 13c unlike tree ring width and density 13c and 18o are not altered by budmouth outbreaks these two parameters therefore appear well suited for climate reconstructions and depict a strong correlation with july august temperature and relative humidity the 18o of larch cellulose is also strongly linked with the previous winter december march oxygen isotopic composition of the precipitation this is consistent with a winter water recharge of soil and ground the past variations of july august maximum temperature and relative humidity were established using two different combinations of the isotopic ratios uncertainties on the reconstructions are estimated respectively at 1 4 c and 3 6 inter annual variations of temperature and relative humidity are well reproduced however the reconstructed july august temperature series diverges from the instrumental one being lower after ca 1990 the effects of the variation through time of the depth of source water and of the ecophysiological response of trees to rising co2 on the isotope composition are discussed as possible causes of divergence this divergence problem strongly questions the possibility of producing appropriate isotope based temperature calibration the relationships between isotopes and the july august relative humidity are more stationary than those with temperature this may reflect the first order control of the relative humidity on 13c via the stomatal conductance and its influence on the evaporative enrichment of the oxygen of the leaf water our study suggests that past variations of relative humidity in the french alps can be accurately estimated using the stable isotope composition of larch cellulose

the southern iberian shear zone a major boundary in the hercynian folded belt a long ductile shear zone extending across the northern parts of sevilla and huelva provinces southwest spain and very probably stretching further west into portugal is characterized by a conspicuously developed l s fabric and the existence of various mylonitic textures the shear zone closely associated with amphibolites of tholeiitic affinity represents an important oceanic suture of the hercynian belt in europe the sense of displacement inferred from microstructures is consistent with southwest directed upthrusting evolving to a left lateral shearing movement

spatial variations of p residuals and deep structure of the european lithosphere spatial variations of these normalized residuals as large as 2 s were derived from events in different focal regions an average residual at each station was calculated from 23 selected groups compiled from 181 events evenly distributed as to their azimuths and distances the 3 d inversion of the residuals yielded very much the same picture of the relatively high and low velocity provinces for the upper layer of the mantle as compared with the map of average residuals the map of average residuals mainly reflects variations in the thickness of the lithosphere and its thermal state regions of low velocities include the pannonian basin and central carpathians the northern apennines and the po plain as well as the rhine graben the rhenish massif and the north german polish platform high velocities are observed in the south western margin of the east european platform and in three well defined zones situated in the inner part of the western alps in the eastern part of the austrian alps and in the eastern carpathians besides the effects of inhomogeneities also anisotropic effects are anticipated from the spatial diagrams of the residuals which show a similar pattern within large tectonic provinces r

topex poseidon observations of mesoscale eddies over the subtropical countercurrent kinematic characteristics of an anticyclonic eddy and a cyclonic eddy 1 relative dynamic heights and geostrophic fields were derived from topex poseidon altimetry data and then used to track mesoscale eddies over the subtropical countercurrent stcc the radii centers vorticities shearing deformation rates stretching deformation rates divergences and center velocities of all identified eddies over the stcc were determined using a model that assumes constant velocity gradients most eddies are concentrated in a zonal band near 22 n and there is an interannual variation in the number of eddies a case study was made for a cyclonic eddy and an anticyclonic eddy with time series of eddy kinematic parameters computed both eddies survive for 220 days and propagate westward along over 22 n 24 n to reach the kuroshio current east coast of taiwan where the eddies were dissipated and in turn affected the kuroshio current in many ways sea surface temperature data and drifter data confirm the existence of these two eddies the radii of both eddies vary and their shapes are mostly elliptical during propagation the anticyclonic eddy propagated almost westward with oscillating north south components and the mean speed is 8 3 km day the cyclonic eddy moved southwestward before reaching 130 e and then moved northwestward with a mean speed of 7 6 km day the propagations of these two eddies are basically consistent with the standard theory of eddy propagation but with larger speeds the propagating direction could be altered while passing steep bottom topography or merging with the other eddies index terms 4520 oceanography physical eddies and mesoscale processes 4576 oceanography physical western boundary currents 4512 oceanography physical currents 4594 oceanography physical instruments and techniques 4556 oceanography physical sea level variations

variations in heat flow across the ocean continent transition in the iberia abyssal plain abstract new heat flow observations have been made in the iberia abyssal plain off the galicia margin along the transect of ocean drilling program leg 149 drill sites in order to investigate the nature of this unusually wide and deep continent ocean transition region our results indicate the presence of three separate zones average values of 47 5 3 mw m 2 in the westernmost zone iii agree with predictions of standard oceanic lithospheric models for its estimated age of 126 ma in contrast the heat flow within zone ii is 5 15 mw m 2 higher than predicted assuming that the mantle heat flow remains constant across the basin this region of high values is coincident with the location of a major intra crustal s type reflector east of odp site 900 and the anomaly is consistent with the presence of 2 3 km of primarily upper continental crust above the reflector with concentrations of radiogenic components similar to those from granodiorite samples dredged off galicia bank it is not however consistent with the low values of heat production measured on gabbroic samples from its western end at odp site 900 in zone i detailed measurements across the tilted fault block south of odp site 901 show consistent variations which closely match predictions due to the effects of basement structure and sediment deposition there is no evidence for variations due to vertical convective transport along the dipping basement fault block once corrected for these variations measurements in zone 1 yield average values that agree quite well with previous measurements across galicia bank indicating no systematic landward increase in heat flow with decreasing amounts of continental extension

the crustal structure in iberia inferred from p wave coda abstract the crustal velocity structure at four locations in the iberian peninsula is inferred from p wave coda recorded by broad band stations the crustal responses of the stations are derived from the p wave coda of deep teleseismic events and the most pronounced features of the p and s velocity structure are obtained by waveform modeling of the vertical and radial component of these responses the method is applied to data of nars stations in toledo alicante and granada in spain and manteigas in portugal the optimum models of the waveform inversions are carefully evaluated and compared to results of deep seismic sounding experiments in general the depths of large velocity gradients are well resolved but the actual values of the seismic velocities are less constrained

numerical experiments on the movement of a warm core ring with the bottom slope of a western boundary numerical experiments are performed to investigate the effects of the bottom slope of a western boundary on realistic warm core rings using a primitive equation sigma coordinate model warm core rings which initially have baroclinic velocity near a steep bottom slope gradually move northward but those with barotropic velocity do not barotropic velocity on the slope immediately disperses as a topographic rossby wave while baroclinic velocity is retained since the northward movement is caused by an effect very much like the image effect which is originally the effect of a free slip wall the authors term this effect the equivalent image effect the equivalent image effect increases as a slope becomes steeper and bottom friction becomes weaker and vice versa it seems that a steep slope acts like a wall and the bottom friction of a steep slope corresponds to the lateral viscous effect of a wall however the effect of a slope on a warm core ring is different from that of a wall in that ring slope interactions take place at the lower part of the ring because the velocity of a warm core ring is weak in deep layers ring slope interactions are moderate and the leakage of the interior fluid of a ring seen in ring wall interactions is not apparent while the viscous effect is weaker than that of a no slip wall as well these results are applied to the northward movement of kuroshio warm core rings and to warm eddies in the gulf of mexico

p wave velocity depth distribution in the hercynian crust of northwest spain abstract the results of a seismic refraction wide angle reflection survey in the hercynian of galicia northwest spain are presented two out of the five seismic refraction profiles obtained in 1982 are discussed in detail and the results are integrated with those already published to give a three dimensional view of the crust the crust is structured in three layers of varying thickness resulting in a moho depth of 26 27 km near the atlantic ocean and 32 km in central galicia the velocity in both the lower crust and the upper mantle are higher in central galicia 6 7 6 9 8 3 km s 1 than close to the atlantic coast 6 6 6 8 8 0 km s 1 the obtained results show remarkable similarities with those reported for other areas of the hercynian crust in western europe

water mass structure of warm and cold anticyclonic eddies in the western boundary region of the subarctic north pacific vertical profile data of temperature and salinity from various sources were analyzed together with satellite altimeter data to investigate the water mass characteristics of warm and cold anticyclonic eddies in the western boundaryregionof the subarctic north pacific a densedistributionof anticyclonic eddieswith warm and saline core water occurred near the kuroshio extension and the distribution extends northward northeastward into the western subarctic gyre along the japan and kuril kamchatka trenches eddies with cold and fresh core water are found mainly around the oyashio southward intrusions and farther north near the kuril islands based on the heat content anomaly integrated over 50 200 dbar 85 of the anticyclonic eddies within the study area 358 508n 1408 1558e have a warm and saline core and 15 have a cold and fresh core warm and saline eddies around the japan and kuril kamchatka trenches have a double core structure with a cold and freshwater mass located below the warm core the northward propagation of these eddies along the trench line results in a large northward heat salinity transport in the upper 400 dbar 250 dbar and a negative salinity transport below 350 dbar the lower core water is colder and fresher on isopycnal surfaces at around 26 70sucompared with the climatology given that the 26 70su isopycnal surface does not outcrop in the open north pacific an alignment process is suggested to occur between the warm and saline and the cold and fresh anticyclonic eddies in the upper and intermediate layers respectively

carbon isotope behaviour in wood and cellulose during artificial aging abstract modern wood was subjected to an artificial decay process to investigate its behaviour with respect to the stable carbon isotope composition of wood and the corresponding cellulose four different woods were used namely oak quercus robur beech fagus sylvatica pine pinus sylvestris sequoia sequoiadendron giganteum and pure spruce cellulose the process of decay was simulated by heating samples in water at 180 c from minutes to months during the decay period the carbon content of wood increased to almost 70 while the cellulose content decreased gradually to zero the degradation proceeds according to a two stage process an initial very fast break down is followed by a rather slow degradation after a strong discrimination against 13 c during the initial phase the 13c 12c ratio increases again mostly up to its initial value the carbon isotope trend for cellulose shows a similar pattern though it is less pronounced maximum discrimination was 1 relative to the untreated wood 13c values of cellulose decreased by up to 0 3 the 13 c depletion is presumably a consequence of the preferential decomposition of cellulose as compared to lignin data on fossil trees are compared with the results obtained from this treatment of aging the 13 c decrease is in line with observations from these fossil woods but the ensuing 13 c enrichment is at most weakly to be seen

do tree ring δ13c series from pinus sylvestris in northern fennoscandia contain long term non climatic trends abstract non climatic trends in tree ring 13 c series are investigated using highly replicated pinus sylvestris 13 c series from finnish lapland the declining trend in stable carbon isotopes over the industrial period reflecting changes in the isotopic ratio of atmospheric co 2 is removed mathematically without recourse to statistical de trending regional curve standardisation rcs is then used to identify and remove the juvenile phase during which 13 c values increase the chronologies all show approximately 1 depletion in the juvenile phase with an average rise of 0 029 year 1 lasting for about 50 years after which trees of very different cambial age capture common variance over the same chronological period there is no evidence of long term age related trends and rcs provides an alternative to simply omitting the juvenile portion of the stable carbon isotope series thus allowing greater sample depth to be retained

comparison of stable carbon and oxygen isotopes in picea glauca tree rings and sphagnum fuscum moss remains from subarctic canada stable isotope ratios from tree rings and peatland mosses have become important proxies of past climate variations we here compare recent stable carbon and oxygen isotope ratios in cellulose of tr

processing and inversion of long period surface wave data collected in the iberian peninsula summary several filtering techniques have been used to remove the effects of multipathing and modal contamination and to isolate the fundamental mode from rayleigh wavetrains group velocity data are obtained by means of the multiple filter technique a time variable filter has allowed the influence of noise as well as the interference produced by higher modes to be removed multiple filtering is then used again to compute group velocities at each station the interstation group velocity for the fundamental mode rayleigh wave is estimated according to the velocities at two stations frequency domain wiener deconvolution is used to compute the phase velocity between two stations the well known three station method is applied to correct the distances travelled by the waves across the array and therefore to determine interstation phase and group velocities in a more accurate manner on the other hand lateral refraction at the atlantic continental edge of the peninsula is also studied phase velocities are corrected for the anelastic effect inversion of the interstation rayleigh wave phase velocities is then made in accordance with generalized inversion theory to obtain theoretical 2 d layered earth models in this paper these methods are applied to rayleigh waves generated by teleseismic events propagating across the iberian peninsula and recorded at wwssn stations as a consequence new and principal features for the iberian lithosphere asthenosphere system are obtained a very interesting feature of the the iberian lithosphere was found a low velocity layer directly under the moho between 39 and 64 km depth with shear velocities ranging from 4 12 to 4 37 km s 1 the iberian asthenosphere which lies between 100 and 180km depth is not an homogeneous layer and shows a negative velocity gradient from top to bottom together with a sudden increase in shear velocity beneath the low velocity zone

interaction of a warm ring with the western slope in the gulf of mexico abstract between november 1985 and may 1986 a warm ring encountered the western slope in the gulf of mexico moved away from the slope and began to dissipate before encountering the slope the ring was quasi circular after encountering the slope it became elliptically shaped with a center of circulation that changed position rapidly and erratically the major axis of the ring rotated rapidly in a clockwise sense as the ring increased in size most probably through interaction with two other rings in the western gulf during this period neither satellite nor in situ data indicated large scale exchange of shelf and ring water when the ring moved eastward then southward away from the slope it was observed to decrease in size by a factor of 3 to 5 the upper layer manifestation of the ring had weakened considerably to the north of the center of the ring was a cyclonic feature which was apparently coupled to the ring and remained so throughout the period examined the cyclone was quasi circular and

recently formed elastic anisotropy and petrological models for the continental subcrustal lithosphere in southern germany this paper advances new evidence for elastic anisotropy in the continental subcrustal lithosphere in southern germany the range of petrological models compatible with the observed azimuthal variation of seismic p wave velocity is explored the azimuthal distribution of amplitudes of mantle phases and the observed increase of p velocity with depth both indicate a continuation of anisotropy with depth together with an increase of preferred orientation even depletion of the upper mantle in basaltic components as suggested by mantle xenoliths from various parts of germany cannot explain the velocity depth and azimuthal amplitude observations without an increase of anisotropy with depth preferred orientation of olivine is the most likely mechanism for the observed phenomena its fast a axis at the moho level is directed towards n22 5 e the b axis is also required to be horizontal i e the b plane one of the preferred glide planes of olivine is vertical with a strike of n22 5 e therefore this preferred glide plane of olivine practically coincides with the plane of maximum horizontal shear stress deduced from fault plane solutions of earthquakes in western germany this is a strong indication that the preferred orientation of olivine is formed in the recent west european crustal stress field leaking into the upper mantle the distribution of velocities to a depth of at least 50 km requires slight horizontal rotation of the a axis with depth by 10 towards n32 e and a change in the modal composition towards a depletion increasing with depth compatible with the composition of mantle xenoliths from western germany further experiments are needed to substantiate this suggestion which could lead to a better understanding of the interaction of crustal and upper mantle stress strain fields

the interaction of a two layer isolated mesoscale eddy with bottom topography abstract the propagation of an isolated mesoscale eddy onto a western bounding topographic slope is examined through the use of a two layer primitive equation numerical model variable parameters in the study are sense of rotation cyclonic anticyclonic vertical structure baroclinic barotropic and layer thickness ratio h1 h2 eddy size and strength rotational velocity and frictional parameterization are fixed dispersion in the isolated eddy is induced by planetary and topographic beta effects giving the eddy an asymmetric distribution this asymmetric distribution allows for nonlinear self advective propagation tendencies these nonlinear tendencies play a key role in the direction of propagation of the eddy specifically in a quiescient background an anticyclone can have eastward propagation tendencies which can overcome planetary and topographic beta effects conversely cyclones can have westward propagation velocities which are augmented greater than maximum rossby wave phase speed b

crust and upper mantle structure of the central iberian meseta spain summary quarry blasts recorded along three lines on the central iberian meseta are used in an attempt to interpret the crustal structure the results of the interpretation of the data together with published surface wave and earthquake data suggest a layered structure of the crust having the following features the basement in some areas covered by up to 4 km of sediments has a p velocity of 6 1 km s 1 a low velocity layer between 7 and 11 km depth seems to exist on the basis of both p and s interpretation of seismic data a thick middle crust of 12 km has a p velocity of 6 4 km s 1 and overlies a lower crust with a mean p velocity of 6 9 km s 1 and a possible slight negative gradient the mean vp vs ratio for the crust is about 1 75 the moho is reached at about 31 km depth and consists of a transition zone at least 1 5 km thick the p velocity of the upper mantle is close to 8 1 km s 1 and the s velocity about 4 5 km s 1 which gives a vp vs ratio of 1 8 for the uppermost mantle a tentative petrological interpretation of the velocities and composition of the layers is given

impacts of climate and river flooding on the hydro ecology of a floodplain basin peace athabasca delta canada since a d 1700 abstract multi proxy paleolimnological analyses on lake sediment cores from spruce island lake 58 50 82 n 111 28 84 w a perched basin in the northern peace sector of the peace athabasca delta pad canada give insights into the relative roles of flow regulation of the peace river and climatic variability on the basin hydro ecology results indicate substantial variability in basin hydro ecology over the past 300 years ranging from seasonal to periodic desiccation in the 1700s to markedly wetter conditions during the early 1800s to early 1900s the reconstruction is consistent with 1 dry climatic conditions that defined the peak of the little ice age and subsequent amelioration evident in conventional ring width and isotopic analyses of tree ring records located hydrologically and climatically upstream of the pad and 2 peace river flood history inferred from sub annual magnetic susceptibility measurements from another lake sediment record in the peace sector of the pad although regulation of the peace river for hydroelectric power generation since 1968 has long been considered a major stressor of the pad ecosystem leading to reduced frequency of ice jam and open water flooding and an extended period of drying our results show that current hydro ecological status is not unprecedented as both wetter and drier conditions have persisted for decades in the recent past under natural climatic variability furthermore paleolimnological evidence from spruce island lake indicates that recently observed dryness is part of a longer trend which began some 20 40 years prior to peace river regulation

variscan intracontinental deformation the coimbra cordoba shear zone sw iberian peninsula the coimbra cordoba shear zone is a major lineament roughly parallel to the nw se variscan structures of the southern iberian peninsula inside the shear zone evidence for a non coaxial strain path exists from structural microstructural and lattice preferred orientation data on quartz plane strain is suggested by the study of microstructures in the xy and yz sections in all formations occurring in the shear zone with increasing strain a mylonitic series develops the deformation contemporaneous with epizonal to mesozonal metamorphism is responsible for 1 1 the regional subvertical foliation oblique to the shear zone 2 2 the well defined subhorizontal lineation striking nw se 3 3 the discrete planes of shear roughly parallel to the shear zone the data are interpreted as resulting from a left lateral slip motion with a displacement of at least 72 km in the light of plate tectonics it is inferred that the coimbra cordoba lineament could have been a suture zone which evolved into an intracontinental left lateral shear zone during the variscan orogeny of the ibero armorican arc

mesoscale eddies in the northwestern pacific ocean three dimensional eddy structures and heat salt transports the region encompassing the kuroshio extension ke in the northwestern pacific ocean 25 n 45 n and 130 e 180 e is one of the most eddy energetic regions of the global ocean the three dimensional structures and transports of mesoscale eddies in this region are comprehensively investigated by combined use of satellite data and argo profiles with the allocation of argo profiles inside detected eddies the spatial variations of structures of eddy temperature and salinity anomalies are analyzed the results show that eddies predominantly have subsurface near surface intensified temperature and salinity anomalies south north of the ke jet which is related to different background stratifications between these regions a new method based on eddy trajectories and the inferred three dimensional eddy structures is proposed to estimate heat and salt transports by eddy movements in a lagrangian framework spatial distributions of eddy transports are presented over the vicinity of the ke for the first time the magnitude of eddy induced meridional heat freshwater volume transport is on the order of 0 01 pw 103 m3 s the eddy heat transport divergence results in an oceanic heat loss south and heat gain north of the ke thereby reinforcing and counteracting the oceanic heat loss from air sea fluxes south and north of the ke jet respectively it also suggests a poleward heat transport across the ke jet due to eddy propagation

mountain building strike parallel motion and mantle anisotropy abstract geophysical and geological evidence indicates that tectonic movements parallel to the strike of orogenic belts and suture zones are the most important mode of displacement during continental collision and oblique subduction several hundred to a few thousand kilometers of displacement may have occurred this way resulting in a pervasive ductile deformation of the lithosphere consequently both crustal and mantle fabrics may reflect these movements and their study using both geological and geophysical methods could supply important clues to lithosphere behavior during mountain building on the basis of kinematic analysis of ductilely deformed crustal rocks in zones of movement a variety of tectonic models have been proposed which differ in 1 1 the timing of strike parallel motions early before or during continental accretion or late after accretion was completed 2 2 the geometric pattern of strike parallel displacement zones low angle or high angle and 3 3 the location of orogen parallel movement zones in outboard terranes on the subducting plate along the suture zone or within the continental hangingwall large scale displacements parallel to mountain belts also suggest that they occurred along lithospheric faults rooted in the upper mantle although few studies have been carried out from this view point thermal structural and petrological data support the conclusion that lithospheric faults involving the upper mantle may be discriminated from crustal faults rooted in some crustal decoupling zone where available data on mantle flow beneath orogenic belts are in agreement with mountain parallel displacements inferred from crustal studies this has an important bearing on the seismic anisotropy pattern which can be predicted in the lithospheric mantle below mountain belts the fast velocity direction which is parallel to the flow direction should therefore be recorded parallel to the strike of the belt

deep deformation pattern from electrical anisotropy in an arched orogen betic cordillera western mediterranean long period magnetotelluric data acquired in the iberian massif and the betic cordillera arched orogen provide the first evidence of electrical anisotropy in the upper mantle of the mediterranean region strike analysis at different periods reveals preferred structure orientation related to olivine elongation in the mantle and points to a heterogeneous anisotropy pattern at deep levels periods 104 s all the sites show a common north south geoelectrical strike n170 e which may represent a low intensity deformation possibly related to frozen prealpine plate tectonics for periods between 10 and 103 s a north south constant strike n180 e at the betic cordillera sites contrasts with the east west strike n85 e in the iberian massif an increase in the magnitude of the induction arrows from the iberian massif to the inner part of the betic cordillera probably reflects higher deformation toward the axis of the eurasian african plate boundary the integration of electrical anisotropy data with seismic anisotropy allows us to discuss mantle deformation patterns produced by delamination and subduction suggesting that the latter mechanism may be more suitable for the alpine evolution of the western gibraltar arc

sea surface temperature changes in the okhotsk sea and adjacent north pacific during the last glacial maximum and deglaciation abstract we estimated sea surface temperatures ssts in the western okhotsk sea during the last glacial maximum lgm and the last glacial termination from measurements of the alkenone unsaturation index u k 37 the t etra e ther inde x of tetraethers consisting of 86 carbon atoms tex 86 and tex 86 l in piston core sediments which reveal the climate response of this region to different types of forcings tex 86 l is a modification of tex 86 proposed for high latitude ocean regions the tex 86 l derived temperatures were not different from the alkenone derived temperatures from the same and nearby sediment samples during the lgm alkenone derived temperatures in the okhotsk sea were relatively warm these and similarly warm alkenone derived temperatures found at many other sites in the western north pacific may reflect a shift in the season of biomarker production from early summer and autumn to mid summer during the lgm as a result of the expansion of the season of sea ice cover empirical orthogonal function eof analysis of alkenone derived temperatures at 14 sites from the north pacific suggested substantial cooling between 20 and 14 cal kyr bp during the deglaciation at 11 of the sites including 4 sites in the okhotsk sea this dominant eof mode suggests either an overall seasonal bias in alkenone derived temperatures or potential shifts in the haptophyseae production season the second eof mode of variability indicated a deglacial warming trend punctuated by millennial scale cold events associated with reorganizations of the atlantic meridional overturning circulation the sst pattern corresponding to this eof mode is indicative of millennial scale meridional shifts of the axis of the westerly jet which may have affected heat transport across the kuroshio reconstructed temperature changes in particular in the okhotsk sea provide insight into the conditions that modulated the ventilation history of intermediate waters in the north pacific

geological constraints on the paleozoic tectonic evolution of tectonostratigraphic terranes in the iberian massif abstract the presence of oceanic paleozoic sequences in the iberian variscan fold belt is used to identify and separate suspected exotic terranes from a reference iberian autochthon terrane which constitutes the greater part of it in this paper the relevant data characterizing the pre accretionary evolution of the paleozoic iberian terranes are presented as well as the available evidence concerning the accretionary process itself emphasis is placed on the analysis of the sedimentary igneous and structural expression of the major events which affected the iberian terranes before during and after their amalgamation the main conclusions of such an analysis may be summarized as follows 1 a recognition of rift and passive margin stages in all the iberian massif terranes during the early paleozoic 2 b late paleozoic accretion of the exotic terranes to the iberian autochthon via a long and complex process variscan orogeny which involved initial subduction underneath the latter and eventual obduction followed by oblique collision of a promontory the iberian autochthon northwestern margin with a northwestern continental block this latter process could account for the large scale crustal imbrication shown by the northern branch of the orogen coeval with predominant strike slip faulting in the southern branch as well as with the formation of the typical arcuate shape of this orogenic belt major present uncertainties relate to the palinspastic provenance of continental suspect terranes and their correlation with similar units in other circum atlantic paleozoic orogens a discussion and speculations on this subject are dealt with in the final section of this paper

the moho depth map of the european plate summary the european plate has a 4 5 gy long and complex tectonic history this is reflected in the present day large scale crustal structures a new digital moho depth map is compiled from more than 250 data sets of individual seismic profiles 3 d models obtained by body and surface waves receiver function results and maps of seismic and or gravity data compilations we have compiled the first digital high resolution map of the moho depth for the whole european plate extending from the mid atlantic ridge in the west to the ural mountains in the east and from the mediterranean sea in the south to the barents sea and spitsbergen in the arctic in the north in general three large domains within the european plate crust are visible the oldest archean and proterozoic crust has a thickness of 40 60 km the continental variscan and alpine crust has a thickness of 20 40 km and the youngest oceanic atlantic crust has a thickness of 10 20 km

love rayleigh wave incompatibility and possible deep upper mantle anisotropy in the iberian peninsula love and rayleigh wave phase velocities are analyzed with the goal of retrieving information about the anisotropic structure of the iberian lithosphere the cross correlation method is used to measure the interstation phase velocities between diverse stations of the iliha network at periods between 20 and 120 s despite the 2 d structure of the network the love wave data are too few to enable an analysis of phase velocity azimuthal variations azimuthal averages of love and rayleigh wave phase velocities are calculated and inverted both in terms of isotropic and anisotropic structures realistic isotropic models explain the rayleigh wave and short period love wave phase velocities therefore no significant anisotropy needs to be introduced in the crust and down to 100 km depth in the upper mantle to explain our data a discrepancy is observed only at long periods where the data are less reliable love wave data at periods between 80 and 120 s remain 0 15 km s faster than predicted by isotropic models explaining the long period rayleigh wave data possibilities of biases in the measurements due to interferences with higher modes are examined but seem unlikely a transversely isotropic model with 8 of s wave velocity anisotropy in the upper mantle at depths larger than 100 km can explain the whole set of data in terms of a classical model of mantle anisotropy this corresponds to 100 of the crystals perfectly oriented in the horizontal plane in a pyrolitic mantle this is a rather extreme model which predicts at time delay between 0 and 2 seconds for split sks

p and sv velocity structure of the south portuguese zone fold and thrust belt sw iberia from traveltime tomography imaging the architecture of the shallow crust of the south portuguese zone fold and thrust belt is essential to extend surface mapped geological information to depth and to help in developing model

westward motion of mesoscale eddies abstract since the pioneering work of nof the determination of the westward drift of mesoscale eddies under the planetary beta effect has been a recurrent theme in mesoscale oceanography and several different formulae have been proposed in the literature here recpatiulation is sought and within the confines of a single layer model a generalized formula is derived although it is similar to nof s the present formula is established from a modified definition and with fewer assumptions it also recaptiulates all other formulae for the one layer model and applies to a wide variety of situations including cases when the vortex develops a wake of rossby waves or undergoes axismmetrization following the derivation of the formula a physical interpretation clarifies the migration mechanism which can be divided between a self induced propulsion and a reaction from the displaced ambient fluid numerical simulations with primitive and geostrophic equations validate the formula for a variety of length sc

characteristics of mesoscale eddies in the kuroshio oyashio extension region detected from the distribution of the sea surface height anomaly abstract this study investigates the distribution of the sea surface height anomaly ssha with the aim of quantifying the characteristics of mesoscale eddies in the kuroshio oyashio extension region koer where intense mesoscale eddies are commonly observed during hydrographic surveys dense distributions of both anticyclonic eddies aes and cyclonic eddies ces are detected for the first time in koer with sufficient temporal and spatial coverage using the okubo weiss parameter without smoothing their contribution to the total ssha variance is estimated to be about 50 the zones of highest amplitudes are located north and south of the axis of the kuroshio extension ke for aes and ces which represent warm core and cold core rings respectively the areas extend poleward along the japan and kuril kamchatka trenches especially for aes eddies of both polarities and with moderate amplitudes are also recognized along the subarctic front saf eddies in areas north and south of the ke generally pro

interpretations of the jebar term abstract in diagnostic calculations of the ocean s circulation the so called jebar joint effect of baroclinicity and relief term may induce a significant depth average current field as has been noted in the oceanographic literature here we present two consistent interpretations of this term in the equation governing the vorticity of the depth averaged current a topographic vortex stretching term proportional to the dot product of depth averaged velocity and the depth gradient arises we show that jebar corrects this term by removing the contribution of the geostrophic flow referenced to the bottom which cannot generate topographic vortex stretching in the evolution equation for the vorticity of the depth integrated flow a bottom torque term is present we show that the jfbar term discussed above enters here as a contribution to the bottom torque emphasizing the role of jebar as a forcing term we also show that when a diagnostic calculation is formulated completely in terms of the transport str

progress in isotope dendroclimatology numerous studies have demonstrated the potential of stableisotopes in tree rings for quantitative terrestrial palaeoclimaticreconstruction ramesh et al 1986 heaton 1999 switsur andwaterhouse 1998 mccarroll and loader 2004 2005 but the earlywidespread application of isotope dendroclimatology has been hin dered by laborious technical procedures that have until recently prevented wider application of this technique and severely con strained progress developments in mass spectrometry preston andowens 1985 barrie et al 1995 filot et al 2006 leuenberger andfilot 2007 and sample preparation techniques leavitt and danzer 1993 loader et al 1997 brendel et al 2000 schulze et al 2004 rinneet al 2005 gaudinskiet al 2005 haverevolutionisedthe eldand enabled development of stable isotope chronologies with aheightened degree of replication gagen et al 2007 and temporalrange treydteetal 2006 thatwaspreviouslynotpracticalandrarelyobserved in any other proxy record outside of dendroclimatology these and associated advances are re ected in the dramatic increasein the number and diversity of isotope tree ring papers presented atrecent international conferences the thirty isotope tree ring paperspresented at the recent 7th international conference on dendrochro nology beijing 11 17june2006 aretrulyinstarkcontrasttothetwodelivered at the 2nd international workshop on global dendroclima tology 1980 long 1982 wigley 1982 in this volume the progressand advances in isotope dendroclimatology are critically reviewed inthe context of the initial work and aspirations of the early pioneers inthis eld and new directions and methodologies are explored dendroclimatology is an established eld of palaeoclimatologyused in its scienti c form since the early 20th century however theapplication of stable isotope techniques to dendroclimatology is morerecent conceptually the seed was planted when urey 1947 statedthat it seems probable that plant carbon compounds synthesised atdifferent temperatures may contain varying amounts of c

crustal structure from gravity signatures in the iberian peninsula through two dimensional fi ltering and spectral analysis of gravity data we infer the density structure of the iberia peninsula s lithosphere western europe the gravity anomaly map of the iberian peninsula displays long wavelength anomaly minima related to alpine ranges these anomalies are primarily linked to a greater crustal thickness low pass filtering of the anomaly map using a cutoff wavelength of 150 km was adequate for effective separation of shallow and deep sources used for computing the three dimensional 3 d moho interface tsuboi s technique identical to the equivalent stratum theorem is used here to map the 3 d moho interface by selecting mean source depths from the results of the spectral analysis and assuming a homogeneous density contrast of 350 kg m3 the most characteristic feature of the 3 d moho geometry was the presence of several lows associated with mountain ranges created by alpine tectonics in those areas the gravity derived moho reaches a depth of up to 45 km in the pyrenees and cantabrian mountains and close to 40 km under the betics central system and iberian chain under the iberian massif the western part of the iberian peninsula composed of a variscan basement the moho was located at a depth of 30 36 km these results are consistent with existing seismic data and indicate that gravity based techniques can provide very good estimates of lithosphere structure

short lived juvenile effects observed in stable carbon and oxygen isotopes of uk oak trees and historic building timbers abstract stable carbon 13 c and oxygen 18 o isotope ratios were measured on the latewood cellulose of individual oak quercus robur l q petraea liebl samples from living trees and historic building timbers this represents the type of material available to produce long tree ring chronologies for north western europe including the uk and ireland results from the juvenile rings those located closest to the pith were compared with results from equivalent sections representing the same calendar years from independent master isotope chronologies that do not contain any juvenile wood allowing any juvenile offsets and trends to be separated from those caused by environmental change oak timbers from archaeological sources are often relatively short pinus sp would severely constrain the material available for chronology construction the aim of this study was to determine the magnitude and duration of juvenile effects including the detection of trends offsets and their influence upon signal strength the results show clearly that juvenile effects for oak from central england are very small and short lived and that removing merely the first five rings closest to the pith is sufficient to avoid them this result greatly increases the potential for building long and well replicated stable isotope chronologies using archived oak samples from historic building timbers allowing high resolution climate reconstructions to be produced for the highly populated regions where oak is abundant and which are currently under represented in regional palaeoclimate reconstructions

a numerical study of loop current eddy interaction with topography in the western gulf of mexico abstract anticyclones originating from the loop current are known to propagate into the western gulf of mexico their frequency of generation their long lifetimes and satellite data suggest that at any one time one or more eddies may occupy the gulf given the eddy sizes 100 200 km and geometric confinement of the gulf it would appear that there may be significant interactions of individual eddies and or interactions of the eddies with bottom topography these possibilities are explored through the use of a two layer primitive equation model variable parameters in this model study are eddy strength vertical structure lateral friction and initial location relative to topography results indicate that eddy motion is governed by two dynamical regimes depending on its lower layer rotational strength anticyclones with significant lower layer anticyclonic structure develop offshore directed self advective tendencies associated with topographic dispersion which induces asymmetry in the eddy eddies wit

riparian influences on carbon isotopic composition of tree rings in the slave river delta northwest territories canada abstract tree ring cores from two white spruce picea glauca trees at each of three sites within the slave river delta northwest territories canada were separated processed for cellulose and analyzed for their carbon isotope composition the three carbon isotope 13 c cellulose time series collectively covering the time period from 1689 to 2003 were statistically correlated with average historical monthly climate grid temperature and precipitation for the period 1901 2000 the results suggest that the trees from all three sites show a distinct trend towards more enriched 13 c cellulose values with time implying more stressful environmental conditions possibly related to the overall 20th century drying of the slave river delta anthropogenic impacts of heavy logging and the construction of a large upstream dam may also be present in the 13 c cellulose time series the main focus of the study relates to the different nature of the three riparian sites the 13 c cellulose values of the trees from the two sites 50 m from the river at higher elevation suggest a relationship with moisture deficit stress mds emanating from hydroclimate effects during the non growing and growing seasons the 13 c cellulose values from a site adjacent to the river at lower elevation however suggest that these same effects can manifest as moisture excess stress mes on the trees the relationships between these two types of moisture stress and the 13 c cellulose values of the trees from the sites with obvious riparian differences are discussed in detail

tree ring width and δ13c records of industrial stress and recovery in pennsylvania and new jersey forests implications for co2 uptake by temperate forests abstract we present dendrochronological records of tree ring width and 13c values for representative living trees ages of 70 to 230 years in pennsylvania and new jersey to investigate the ecological responses to industrial pollution and recent management and their effects on carbon storage in the temperate forests chestnut oak red oak and cedar trees consistently show elevated 13c levels 1 3 to 4 1 higher than unpolluted normal values during the period of intense pollution from 1900 to 1970 indicating significant industrially induced physiological stress on the trees since 1970 oak and cedar trees have shown remarkable increase in growth rates and rapid decrease of 0 6 to 2 5 in 13c values indicating the recovery of trees corresponding to the implementation of the clean air act in the early 1970s the growth enhancement since 1970 has resulted in an increase in biomass of 26 in cedar trees and 66 in oak trees suggesting that air cleaning efforts have made a significant contribution to co2 uptake by the temperate forests at least in the northeastern usa

azimuthal anisotropy in the earth from observations of sks at geoscope and nars broadband stations abstract we have analyzed observations of low frequency sks waves recorded on horizontal components at several broadband stations of the geoscope and nars arrays splitting of sks is consistently observed and in good agreement with a hypothesis of azimuthal anisotropy due to transverse anisotropy with a horizontal axis in the upper mantle beneath the receivers we have designed an inversion method which takes advantage of observations made simultaneously at different azimuths and which permits us to obtain estimates of the direction of fast axis of anisotropy as well as the time delay between the orthogonal quasi shear waves in general the directions of fast velocity obtained both for stations around the atlantic and around the pacific appear to be related to directions of past and present plate motions

lateral inhomogeneities of the hercynian crust in central spain abstract an azimuthal layout of deep seismic profiles has been partially completed in the central iberian massif data from two new profiles and a reinterpretation of previous profiles make possible two dimensional models for the hercynian crust in central spain from which some lateral crustal inhomogeneities can be established these inhomogeneities due to alpine intraplate tectonics coincide with the spanish central system and consist of a 5 km crustal thickening with respect to the surrounding areas

p wave anisotropy in the lower lithosphere abstract long range controlled source seismic experiments yield detailed information about the velocity depth structure of the lower lithosphere between ireland and northern britain three such profiles sample almost the same portion of the subcrustal lithosphere three zones with steep velocity gradients have been detected between 30 km and 90 km depth both the pattern and velocity of the arrivals are incompatible with isotropy preferential alignment of olivine crystals with an azimuth ca n25 e for the fast axis could explain the observations with the more highly aligned zones occurring in bands or layers separated vertically by zones in which the degree of alignment is slight or absent we suggest that a shear heating mechanism may have played a part in producing these patterns this deformation is most likely to be of mesozoic or early cenozoic age it is argued that the upper mantle is not necessarily a strain marker for the last major orogenic episode as recent findings have suggested 1 since it may undergo deformation which decouples from the brittle upper crust and hence is not transmitted to the earth s surface

azimuthal seismic anisotropy in a zone of exhumed continental mantle west iberia margin summary p wave azimuthal seismic anisotropy of the uppermost mantle has been shown to indicate directions of extension both recent and fossil in oceanic and continental settings we have determined the p wave anisotropy of a zone of exhumed continental mantle beneath the southern iberia abyssal plain as a possible indication of the initial direction of separation of iberia from north america in a region where there are no magnetic lineations or fracture zone lineations adjacent to the margin with which to constrain this direction over 10 000 airgun shots were recorded by 11 ocean bottom seismometers hydrophones from which 24 900 arrivals that had traversed unaltered weakly serpentinized upper mantle were picked complete 360 azimuthal coverage was attained between the shots and receivers for ranges up to 55 km p wave raypaths through the zone of exhumed continental mantle were ray traced through a velocity model that incorporated the 3 d relief of the seabed and acoustic basement time residuals with respect to this model were fitted using an azimuthally dependent function small anisotropy 7 per cent with a fast direction of 143 was determined to exist between 3 1 and 6 7 km below the top of the basement although the fast direction suggests that the post breakup mantle stretching between iberia and north america was northwest southeast this hypothesis is hard to reconcile with other observations instead we conclude that motion along concave downward faults during the exhumation of the upper mantle could have been sufficient to change an initially roughly east west margin normal fast direction to the 143 azimuth observed today the degree of serpentinization was estimated to decrease from 20 to 0 per cent between 3 and 7 km depth into the basement in the zone of exhumed continental mantle the degree of upper mantle anisotropy is similar to that observed in other oceanic and continental settings where similar degrees of serpentinization are inferred from mean p wave velocities

interaction of barotropic vortices with coastal topography laboratory experiments and numerical simulations the interaction of a barotropic cyclonic vortex on a b plane with a strong topographic slope is studied by means of laboratory experiments and numerical simulations in the laboratory the vortex is produced in a rectangular rotating tank with a weak uniformly sloping bottom slope angle 3 58 in order to simulate the b effect the cyclonic vortex moves in the northwestward direction and interacts with an additional pronounced linear topography slope angle 358 along the western boundary of the tank the laboratory experiments revealed that the original northwestward trajectory changes to the south until the vortex is dissipated by viscous effects and bottom friction as it moves upslope the exterior ring of the vortex forms a strong current to the northeast from this current a new cyclonic vortex is created repeating approximately the behavior of the original one later two more vortices are formed in the same way a finite difference numerical model is used to solve the nondivergent barotropic equation despite the presence of the strong slope agreement between laboratory results and numerical runs suggests that conservation of potential vorticity is indeed the basic mechanism involved in the southward motion of the vortex and the northeastward meandering current

a deep seismic reflection survey across the betic chain southern spain first results abstract two land seismic reflection profiles across the betic chain have imaged the deep structure of the crust belonging to two different crustal domains to the north one profile samples the crust of the variscan iberian massif that underlies the sedimentary cover of both the guadalquivir foreland basin and the south iberian crustal domain the upper crust is non reflective along the profile but the lower crust is reflective in the northern half of the profile between 7 and 12 s two way travel time in this segment of the profile the mono is also well imaged the quality of the data diminishes significantly as the profile enters the neogene guadix baza basin a second profile crossing the alpine metamorphic complexes of the betics reveals a reflective lower crust and a conspicuous reflection in the upper crust that is continuous for about 10 km at 11 s a distinct reflection has been interpreted as the reflection moho deeper reflections are also seen in the central part of the profile in a segment about 10 km long comparison with available refraction and wide angle reflection data shows some differences in both the crustal configuration and in the depth to the moho

the destruction of lenses and generation of wodons abstract since midocean eddies migrate westward they eventually reach the western boundaries it is therefore of interest to find out what happens after the eddies collide with the walls an isopycnic two layer primitive equation model on a plane and a simple analytical model on an f plane are constructed to investigate the meridional migration of an oceanic eddy along a western wall on a plane three factors determine the eddy s migration along a western meridional wall first the image effect pushes an anticyclonic cyclonic eddy northward southward second the force resulting from the larger coriolis force on the northern side of the eddy pulls an anticyclonic cyclonic eddy southward northward third after an anticyclonic cyclonic eddy collides with the wall parts of the anticyclonic eddy s interior fluid leak out southward northward along the wall forming a thin jet in an analogy to a rocket this jet pushes the eddy northward southward our aim is to investigate in whi

evolution and modulation of a poleward propagating anticyclonic eddy along the japan and kuril kamchatka trenches to investigate the relationships between the movement of an eddy and its interior structure and water properties four profiling floats were deployed in an anticyclonic eddy in the western north pacific in 2013 april october daily float profiles showed rapid changes in temperature and salinity corresponding to strong interactions between eddies north of the subtropical kuroshio extension after the first interaction with a warm core eddy in april the isolation of the winter mixed layer from the surface was observed forming a subsurface remnant layer another interaction with a cold fresh eddy at middepths in may resulted in the formation of a multilayer structure the eddy then moved poleward along the japan and kuril kamchatka trenches indicating changes in its propagation pattern coupled to its interior structure the eddy then moved northward june july stalled july august and moved eastward august october in addition to a general declining trend the properties of the warm saline core changed over a short time period coinciding with changes in propagation a density anomaly at middepths of the eddy changed location during the stalled period however denser waters were continuously observed in the southeast part of the eddy during its northward and eastward movement this unidirectional density anomaly pattern was consistent with the structure of the poleward propagating eddy which interacted with the western topographic boundary meridional exchanges of heat and material were potentially elevated by the eddy s advection and movement as well as by water modifications in the eddy associated with exchanges along its perimeter

prospects for reconstruction of seasonal environment from tree ring δ13c baseline findings from the great lakes area usa abstract plant 13 c and discrimination 13 c air 13 c plant embody ecophysiological response to environmental conditions influencing rates of carbon fixation and stomatal conductance this study scrutinizes the seasonal variation of 13 c and in growth rings developed in 1990 as represented in trees of 11 species at three sites along a 5 latitude transect in illinois and wisconsin usa radial stem xylem growth of the trees was monitored with monthly punch cores and the resulting growth curves precisely identified the growth period represented in the five segments into which each growth ring was subdivided seasonal 13 c variation of cellulose was usually 1 1 5 and the seasonal patterns were similar among angiosperm and conifer trees at a site with angiosperms generally 13 c depleted by 0 5 1 5 seasonal 13 c and patterns was different among sites however and regression with several environmental parameters revealed most frequent significant correlation with soil moisture palmer drought severity index pdsi the site averaged seasonal patterns track each of their divergent local seasonal drought index chronologies very well even when isotopic curves of the different trees are simply averaged without adjustment for different growth rates seasonal tree ring 13 c analysis is affirmed as a valuable method for assessing seasonal moisture status furthermore results favor successful extension to ancient tree rings where different species and slope aspects may be represented in wood samples at a collection site and where rates of ring development and seasonal 13 c air are not likely to be known

stable carbon isotope ratios of pinus sylvestris from northern finland and the potential for extracting a climate signal from long fennoscandian chronologies stable carbon isotope ratios were measured on the latewood cellulose of 36 scots pine trees from four sites in northern finland 13c values were corrected for changes in the 13c of air and de trended to remove the effect of tree age simple linear and multivariate correlations were used to determine the nature and strength of any climate signal at three sites the dominant controls are in descending order summer sunshine temperature and antecedent precipitation at the fourth site the dominant controls are antecedent precipitation and air relative humidity while summer sunshine and temperature appear unimportant 13c values record changes in the concentration of co2 in the stomatal chambers which reflects the balance between stomatal conductance and photosynthetic rate photosynthetic rate is controlled primarily by photon flux sunshine and temperature suggesting that this dominates at three of the sites whereas stomatal conductance is controlled by air humidity and soil moisture status ant