seismic and geoelectric evidence for collisional and extensional events in the fennoscandian shield implications for precambrian crustal evolution extensive deep seismic and electromagnetic sounding programs have resulted in tens of deep refraction seismic profiles normal incidence reflection profiles several hundred magnetotelluric soundings and several magnetovariational array observations results are compiled into four maps 1 moho depth 2 thickness of the lower crustal high velocity layer vp 7 km s 3 depth to the upper interface of the high velocity layer and 4 distribution of upper and middle crustal electrical conductors the moho depth is approximately 40 km in the archaean domain and varies between 40 and 65 km in the svecofennian domain most of the thickness variation 0 24 km is concentrated in the lower crustal high velocity layer electrically the crust is formed of several rather homogeneous either resistive or conductive blocks that are bounded by upper and middle crustal conductive zones the cratonized archaean crust experienced an extensional phase during which a thin mafic lower crustal high velocity layer was produced in association with mafic dykes 2 2 2 1 ga and well conducting volcanogenic and metasedimentary belts 2 5 2 0 ga the moho of the archaean domain was consequently reformed in the early proterozoic major thickening of the crust 50 65 km occurred when a svecofennian island arc and the archaean craton collided the svecofennian orogeny 1 76 1 9 ga resulted in a collage of metasedimentary rocks squeezed between crustal blocks of the island arc the internal terrane boundaries are seen as good reflectors and or inclined or vertical conductors that extend at least to the middle crust the thick high velocity 7 km s lower crust is a combination of mafic lower crust of the island arc crustal blocks and mafic additions from either delamination of the lithosphere after the collision or from a period of late svecofennian subduction the collisional boundary is also preserved as a discontinuous conductive zone between the archaean and svecofennian domains the thickened crust was subsequently thinned to 42 km along e w striking zones during an extensional period characterized by the intrusion of anorogenic rapakivi granitoid batholiths coeval mafic dykes and gabbro anorthosite bodies 1 6 1 5 ga the crust of the central part of the shield has since remained virtually intact

intensification variability of tropical cyclones in directional shear flows vortex tilt convection coupling abstractthe coupling of vortex tilt and convection and their effects on the intensification variability of tropical cyclones tcs in directional shear flows is investigated in this study the he

composition and structure of the central aleutian island arc from arc parallel wide angle seismic data new results from wide angle seismic data collected parallel to the central aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and trends in major element geochemistry the 3 d ray tracing 2 5 d inversion of this sparse wide angle data set which incorporates independent phase interpretations and new constraints on shallow velocity structure produces a faster and smoother result than a previously published velocity model middle crustal velocities of 6 5 7 3 km s over depths of 10 20 km indicate an andesitic to basaltic composition high lower crustal velocities of 7 3 7 7 km s over depths of 20 35 km are interpreted as ultramafic mafic cumulates and or garnet granulites the total crustal thickness is 35 37 km this result indicates that the aleutian island arc has higher velocities and thus more mafic compositions than average continental crust implying that significant modifications would be required for this arc to be a suitable building block for continental crust lateral variations in average crustal velocity below 10 km roughly correspond to trends in major element geochemistry of primitive mg 0 6 lavas the highest lower crustal velocities and presumably most mafic material are detected in the center of an arc segment between unmak and unalaska islands implying that arc segmentation exerts control over crustal composition

revisiting azimuthally asymmetric moist instability in the outer core of sheared tropical cyclones abstractthis study revisits the characteristics and physical processes of the azimuthally asymmetric distribution of moist instability in the outer core of vertically sheared tropical cyclones tcs

the evolution of vortex tilt and vertical motion of tropical cyclones in directional shear flows abstractrecent studies have demonstrated the importance of moist dynamics on the intensification variability of tropical cyclones tcs in directional shear flows here we propose that dry dynamic

rapid weakening of tropical cyclones in monsoon gyres over the tropical western north pacific abstractas one major source of forecasting errors in tropical cyclone intensity rapid weakening of tropical cyclones an intensity reduction of 20 kt or more over a 24 h period over the tropical open ocean can result from the interaction between tropical cyclones and monsoon gyres this study aims to examine rapid weakening events occurring in monsoon gyres in the tropical western north pacific wnp basin during may october 2000 2014 although only less than one third of rapid weakening events happened in the tropical wnp basin south of 25 n more than 40 of them were associated with monsoon gyres about 85 of rapid weakening events in monsoon gyres occurred in september and october the rapid weakening events associated with monsoon gyres are usually observed near the center of monsoon gyres when tropical cyclone tracks make a sudden northward turn the gyres can enlarge the outer size of tropical cyclones and tend to induce prolonged rapid weakening events with an average duration of 33 2 h the la

on the sensitivity of tropical cyclone intensification under upper level trough forcing this study is part of the efforts undertaken to resolve the bad trough good trough issue for tropical cyclone tc intensity changes and to improve the prediction of these challenging events sensitivity experiments are run at 8 km resolution with vortex bogusing to extend the previous analysis of a real case of tc trough interaction dora in 2007 the initial position and intensity of the tc are modified leaving the trough unchanged to describe a realistic environment simulations are designed to analyze the sensitivity of tc prediction to both the variety of tc trough configurations and the current uncertainty in model analysis of tc intensity and position results show that tc intensification under upper level forcing is greater for stronger vortices the timing and geometry of the interaction between the two cyclonic potential vorticity anomalies associated with the cutoff low and the tc also play a major role in storm intensification the intensification rate increases when the tc initially located 12 northwest of the trough is displaced 1 closer by allowing a gradual deformation and equatorward tilting of the trough both scenarios foster an extended inflow channel of cyclonic vorticity at midlevels toward the vortex inner core conversely unfavorable interaction is found for vortices displaced 3 or 4 east or northeast variations in environmental forcing relative to the reference simulation illustrate that the relationship between intensity change and the 850 200 hpa wind shear is not systematic and that the 200 hpa divergence 335 350 k mean potential vorticity or 200 hpa relative eddy momentum fluxes may be better predictors of tc intensification during tc trough interactions

on the influences of vertical wind shear on symmetric tropical cyclone structure derived from amsu abstract axisymmetric temperatures and gradient balanced winds associated with tropical cyclones derived from the advanced microwave sounding unit are stratified by the 24 h averaged vector difference of the horizontal wind between 200 and 850 hpa or vertical wind shear using 186 total cases that are limited to tropical cyclones with intensities greater than 33 m s 1 or mature and are located over sea surface temperatures greater than 26 4 c vertical wind shear based composites are created results show that as the vertical wind shear increased the upper level warm core structure associated with the tropical cyclone descended resulting in a shallower balanced vortex these observationally based results are presented in the context of recent mesoscale modeling results of the effect of shear on tropical cyclone structure

a numerical study on rapid intensification of typhoon vicente 2012 in the south china sea part i verification of simulation storm scale evolution and environmental contribution abstracttyphoon vicente 2012 underwent an extreme rapid intensification ri over the northern south china sea just before its landfall in south china the extreme ri the sudden track deflection and the inner and outer core structures of vicente were reasonably reproduced in an advanced research version of the weather research and forecasting wrf arw model simulation the evolutions of the axisymmetric inner core radar reflectivity and the primary circulation of the simulated vicente before its landfall were verified against the doppler radar observations two intensification stages were identified 1 the asymmetric intensification stage i e ri onset represented by a relatively slow intensification rate accompanied by a distinct eyewall contraction and 2 the axisymmetric ri stage with very slow eyewall contraction results from a storm scale tangential wind tendency budget indicated that the primary spinup mechanism during the first stage was the radial eddy momentum transport which was ben

the unexpected rapid intensification of tropical cyclones in moderate vertical wind shear part ii vortex tilt abstractwe investigate a class of tropical cyclones tcs that undergo rapid intensification ri in moderate vertical wind shear through analysis of a series of idealized model simulations two ke

integrated seismic studies of the baltic shield using data in the gulf of bothnia region in the autumn of 1989 a co operative experiment involving 12 research institutions in northwestern europe collected 2268 km of deep seismic reflection profiles in the gulf of bothnia and the baltic

reintensification and eyewall formation in strong shear a case study of typhoon noul 2015 abstractstrong vertical wind shear produces asymmetries in the eyewall structure of a tropical cyclone tc and is generally a hostile environment for tc intensification typhoon noul 2015 howev

effects of vertical wind shear on the intensity and structure of numerically simulated hurricanes a series of numerical simulations of tropical cyclones in idealized large scale environments is performed to examine the effects of vertical wind shear on the structure and intensity of hurricanes the simulations are performed using the nonhydrostatic pennsylvania state university national center for atmospheric research fifth generation mesoscale model using a 5 km fine mesh and fully explicit representation of moist processes when large scale vertical shears are applied to mature tropical cyclones the storms quickly develop wavenumber one asymmetries with upward motion and rainfall concentrated on the left side of the shear vector looking downshear in agreement with earlier studies the asymmetries develop due to the storm s response to imbalances caused by the shear the storms in shear weaken with time and eventually reach an approximate steady state intensity that is well below their theoretical maximum potential intensity as expected the magnitude of the weakening increases with increasing shear all of the storms experience time lags between the imposition of the large scale shear and the resulting rise in the minimum central pressure while the lag is at most a few hours when the storm is placed in very strong 15 m s21 shear storms in weaker shears experience much longer lag times with th e5ms 21 shear case showing no signs of weakening until more than 36 h after the shear is applied these lags suggest that the storm intensity is to some degree predictable from observations of largescale shear changes in all cases both the development of the asymmetries in core structure and the subsequent weakening of the storm occur before any resolvable tilt of the storm s vertical axis occurs it is hypothesized that the weakening of the storm occurs via the following sequence of events first the shear causes the structure of the eyewall region to become highly asymmetric throughout the depth of the storm second the asymmetries in the upper troposphere where the storm circulation is weaker become sufficiently strong that air with high values of potential vorticity and equivalent potential temperature are mixed outward rather than into the eye this allows the shear to ventilate the eye resulting in a loss of the warm core at upper levels which causes the central pressure to rise weakening the entire storm the maximum potential vorticity becomes concentrated in saturated portions of the eyewall cloud aloft rather than in the eye third the asymmetric features at upper levels are advected by the shear causing the upper portions of the vortex to tilt approximately downshear the storm weakens from the top down reaching an approximate steady state intensity when the ventilated layer can descend no farther due to the increasing strength and stability of the vortex at lower levels

crustal structures of eastern fennoscandia the area of the eastern fennoscandian shield is quite well covered by deep seismic sounding profiles most of which were shot in the last ten years in general the velocities of the seismic waves in the crust increase continuously with depth but intense reflections also indicate the presence of distinct velocity boundaries the velocities of the refracted waves in the various profiles resemble each other but the depths to the boundaries vary considerably low velocity zones were found in the uppermost crust along most of the profiles the eastern karelia profiles also exhibited large low velocity zones in the lower part of the crust high velocity bodies found in the uppermost crust in eastern fennoscandia are thought to be associated with mafic intrusions and mafic metavolcanic rocks the depth to the moho shows considerable lateral variation and deep depressions in this boundary are thought to be connected with large fracture zones high pn wave velocities of about 8 5 km s are in many cases associated with these depressions

a statistical analysis of vertical shear effect on tropical cyclone intensity change in the north atlantic 1 based on the best track data of tropical cyclones tcs in the north atlantic and the ncep ncar reanalysis during 1981 2008 the effect of vertical wind shear vws between different vertical levels and with different directions of shear on tc intensity change for tcs of different intensities translational speeds and latitudes were statistically analyzed the results show that tc intensity change and vws are generally negatively correlated indicating the overall negative effect of vws on tc intensity the strong slow moving and low latitude tcs are strongly affected by vws in a deep layer while the weak fast moving and high latitude tcs are subject to strong effect by vws in the mid lower troposphere furthermore overall easterly shear especially in the mid lower troposphere has considerably weaker effects on tc intensity change than westerly shear because part of the easterly shear could be offset by the beta induced northwesterly shear

upper ocean thermal structure and the western north pacific category 5 typhoons part ii dependence on translation speed abstract using new in situ ocean subsurface observations from the argo floats best track typhoon data from the u s joint typhoon warning center an ocean mixed layer model and other supporting datasets this work systematically explores the interrelationships between translation speed the ocean s subsurface condition characterized by the depth of the 26 c isotherm d26 and upper ocean heat content uohc a cyclone s self induced ocean cooling negative feedback and air sea enthalpy fluxes for the intensification of the western north pacific category 5 typhoons based on a 10 yr analysis it is found that for intensification to category 5 in addition to the warm sea surface temperature generally around 29 c the required subsurface d26 and uohc depend greatly on a cyclone s translation speed it is observed that even over a relatively shallow subsurface warm layer of d26 60 70 m and uohc 65 70 kj cm 2 it is still possible to have a sufficient enthalpy flux to intensify the storm to category 5

the effect of vertical shear on tropical cyclone intensity change abstract the effect of vertical shear on tropical cyclone intensity change is usually explained in terms of ventilation where heat and moisture at upper levels are advected away from the low level circulation which inhibits development a simple two layer diagnostic balance model is used to provide an alternate explanation of the effect of shear when the upper layer wind in the vortex environment differs from that in the lower layer the potential vorticity pv pattern associated with the vortex circulation becomes tilted in the vertical the balanced mass field associated with the tilted pv pattern requires an increased midlevel temperature perturbation near the vortex center it is hypothesized that this midlevel warming reduces the convective activity and inhibits the storm development previous studies have shown that diabatic heating near the storm center acts to reduce the vertical tilt of the vortex circulation these studies have also shown that there is an adiabatic process that acts to redu

1 88 1 87 ga post kinematic intrusions of the central finland granitoid complex a shift from c type to a type magmatism during lithospheric convergence abstract the evolution of the svecofennian orogen spans from 1 95 ga to 1 80 ga with the main crust forming activity having taken place 1 90 1 87 ga ago subsequent deformation was largely concentrated to southern finland where transpressional structures indicate lithospheric convergence until 1 80 ga much of the svecofennian orogen in finland is occupied by the central finland granitoid complex cfgc that mainly consists of i type granodiorite and granite these 1 89 1 88 ga intrusive rocks are typically foliated and considered synkinematic a distinct suite of post kinematic undeformed or slightly foliated plutons crosscut the synkinematic rocks they are predominantly quartz monzonites and monzogranites and have been divided into three types according to their petrographic mineral and chemical characteristics compared to the calc alkaline synkinematic granitoids the post kinematic suite generally has an alkaline affinity with higher fe ti k ba zr and nb and lower mg ca and sr at a given sio 2 content the type 1 post kinematic plutons are peraluminous and contained a prominent sedimentary component in their source the types 2 and 3 plutons are marginally metaluminous to peraluminous the type 2 granites especially those in the western cfgc approach the classic 1 65 1 54 ga rapakivi granites of southern finland in their petrographic characteristics magmatic association tholeiitic mafic rocks and elevated contents of incompatible elements and hence have a type characteristics the type 3 plutons contain a pyroxene bearing margin type 3a or contain pyroxene throughout type 3b the type 3b rocks have c type charnockite magma type affinities and some plutons of this subgroup are alkaline the type 3a plutons appear to be transitional between the type 2 and type 3b plutons the synkinematic magmatic episode in the cfgc area probably involved partial melting of intermediate high k rocks in the lower crust with a magmatic addition from a mafic underplate this magmatic episode left a hornblende and biotite poor granulitic residue in the lower crust heat from the mafic underplate triggered partial melting of the granulite to produce the post kinematic magmatism and also introduced mafic material into the post kinematic magmas the post kinematic magmatism took place over quite a short time period ca 15 ma during overall lithospheric convergence it extended beyond the cfgc area and registers a temporal shift from the northeast toward the west and a general change in the character of magmatism from c type to a type the post kinematic magmatism probably resulted from extensional or transtensional events modifying the tectonically thickened crust partial melting of the mafic lower crust produced c type magmatism soon after the first melting episode the crust was already rather rigid and allowed the mafic magmas to follow a tholeiitic trend when the bimodal a type magmas were formed in the western cfgc

the crustal structure along the polar profile from seismic refraction investigations abstract seismic refraction investigations along a 440 km long profije on the northern baltic shield have resolved the crustal structure in this area of archaean to early proterozoic lithosphere formation the profile called the polar profile extends approximately along a sw ne oriented line from the karelian province in northern finland across the lapland granulite belt and the kola peninsula province to the varanger peninsula in northeastern norway at six shotpoints large explosions 200 1680 kg and at three shotpoints small explosions 80 kg were detonated and recorded at an average station spacing of 2 km providing high quality record sections a two dimensional cross section of the crust was obtained by forward modelling using ray tracing techniques high velocity bodies are found in the upper crust related to the karasjok kittila greenstone belt and the lapland granulite belt they extend to a depth of 6 13 km in the karelian province in the southwest a low velocity zone was found between the depths of 8 and 14 km the middle crust shows a slight increase in the average velocities from the southwest to the northeast and a small velocity jump is found along a mid crustal boundary between 18 and 21 km the thickness of the middle crust varies between 16 and 18 km the lower crust and the crust mantle boundary moho show considerable lateral variation the top of the lower crust lies between 26 and 33 km while its thickness decreases from 21 km in the southwest to 10 14 km beneath the lapland granulite belt and the inari terrain reaching 20 km again in the extreme northeast the velocities also change laterally the thin lower crust is characterized by rather low velocities 6 8 6 9 km s whereas in the southwest and northeast the velocities 6 9 7 3 km s resemble more typical shield structures the moho is found at 47 km in the karelian province rises to 40 km beneath the lapland granulite belt and descends to 46 km in the northeastern part of the kola peninsula province the upper mantle velocities at the moho range from 8 1 km s in the region of the thin crust to 8 5 km s and more beneath the karelian province it is tempting to suggest that the anomalous lower crust underlying the lapland granulite belt and the inari terrain may represent the remnants of an early proterozoic back arc basin that was active prior to the 2 0 to 1 9 ga plate convergence event during which the lapland granulite belt was thrust onto the archaean basement of the karelian province another explanation is to assume that the velocity reduction in the anomalous lower crust was caused by a rather pronounced uplift of this region following the 1 9 ga collision event

the relationship between storm motion vertical wind shear and convective asymmetries in tropical cyclones abstract the influence of the direction of storm motion on the azimuthal distribution of electrified convection in 35 atlantic basin tropical cyclones from 1985 to 1999 was examined using data from the national lightning detection network in the inner 100 km flashes most often occurred in the front half of storms with a preference for the right front quadrant in the outer rainbands r 100 300 km flashes occurred predominantly to the right of motion although the maximum remained in the right front quadrant the results are shown to be consistent with previous studies of asymmetries in rainfall radar reflectivity and vertical motion with respect to tropical cyclone motion the motion effect has been attributed to the influence of asymmetric friction in the tropical cyclone boundary layer the authors previously found a strong signature in the azimuthal distribution of lightning with respect to vertical wind shear because both effects show clearly vertical wind shear and storm motion must themse

continental crust crustal underplating and low q upper mantle beneath an oceanic island arc a detailed structural model of the crust subducting slab and underlying upper mantle across the northern izu ogasawara bonin island arc system is derived from a marine seismic reflection and ocean bottom seismographic refraction survey and subsequent forward modeling combined with tomographic inversion the model indicates that the crust is thickest beneath the presently active rift zone and a granitic crust may have formed in the mid crust a highly attenuative mantle that is one with low quality q seems to be confined mainly beneath the presently active rift zone in contrast high p wave velocity persists in the lower crust between the forearc and eastern margin of the back arc basin suggesting a large scale magma input responsible for the arc formation

the accretionary svecofennian orogen insight from the babel profiles abstract the babel profiles b c 1 7 form a 1200 km long nearly continuous cross section through the svecofennides the near vertical marine reflection profiles display a wide range of crustal structures that can be associated with both the accretionary svecofennian orogeny 1 96 1 75 ga and the following subjotnian and jotnian rift stages 1 65 1 11 ga the svecofennian accretionary orogeny took place when a number of micro plates with island arc affinities and surface expression of a large archipelago accreted to the continental karelian plate some of the accreting terranes seem to have had older cores that have acted as crustal indentors during the collision babel profiles 3 and 4 image a series of collisional terrane boundaries between karelian continental margin savo arc sa and central finland arc cfa in the north the karelian margin has been both over and underthrust by the savo arc cfa comprises a folded thrust package on top of a continental nucleus and the savo arc the associated subduction zone and accretionary prism are interpreted to lie to the south underneath the bothnian basin area where prominent ne dipping lower to middle crustal reflections are found along babel profiles 1 and 4 an oblique collision of the central finland arc and the continent resulted in the development of the strike slip fault on the young hot savo arc babel profiles 1 6 7 and c image the internal architecture of the southern and central finland arcs the unusually thick crust 55 60 km hosts unreflective high density mafic intrusions acting as a crustal indentor a highly reflective antiform structure developed on the southern side of it southern finland arc complex sfa is an imbrication structure comprising stacked slices of arc related crust on an older continental nucleus bergslagen nucleus prior to the collision the sfa suffered from gravitational collapse during which the crust was thinned profile b images the architecture of the central and southern swedish svecofennides the sormland terrane sob is interpreted as the accretionary prism of the southern finland arc squeezed between the svecofennian collage in the north and the advancing continent to the south the southern continent island arc is characterised by ne dipping crustal reflections and moho offsets as well as step wise increasing thickness of the crust after the final collision large volumes of mantle derived material intruded the crust as large mushroom shaped plutons they are interpreted as the heat source for the tib magmatism in southern and western scandinavia

a numerical study of convective scale structures in the outer cores of sheared tropical cyclones 1 updraft traits in different vertical wind shear magnitudes

lithospheric structure in northwestern canada from lithoprobe seismic refraction and related studies a synthesis the snorcle refraction wide angle reflection r war experiment snore 97 included four individual lines along the three transect corridors a combination of snore 97 results with those from earlier studies permits generation of a 2000 km long lithospheric velocity model that extends from the archean slave craton to the present pacific basin using this model and coincident near vertical incidence nvi reflection data and geological information an interpreted cross section that exemplifies 4 ga of lithospheric development is generated the velocity structural models correlate well with the reflection sections and provide additional structural compositional and thermal constraints geological structures and some faults are defined in the upper crust at a larger scale the seismic data identify a variety of orogenic styles ranging from thin to thick skinned accretion in the cordillera and crustal scale tectonic wedging associated with both paleoproterozoic and mesozoic collisions models of poisson

a numerical study of outer rainband formation in a sheared tropical cyclone abstractthe dynamical process of outer rainband formation in a sheared tropical cyclone tc is examined in this study using the fully compressible nonhydrostatic tc model after the easterly vertical wind shear of 10 m s 1 was imposed upon an intensifying strong tc an outer rainband characterized by a wavenumber 1 structure formed as a typical principal rainband downshear further analysis indicates that the outer rainband formation was closely connected to the activity of the inner rainband previously formed downshear moving radially outward the inner rainband tended to be filamented owing to the strong radial gradient of angular velocity as the inner rainband approached the outer boundary of the inner core convection in its middle and upwind segments reinvigorated and nascent convective cells formed upwind of the rainband caused mainly by the decreased filamentation and stabilization subsequently the rainband reorganized into a typical outer rainband three different scenarios are found to be

observed hurricane wind speed asymmetries and relationships to motion and environmental shear abstractwavenumber 1 wind speed asymmetries in 35 hurricanes are quantified in terms of their amplitude and phase based on aircraft observations from 128 individual flights between 1998 and 2011 the impacts of motion and 850 200 mb environmental vertical shear are examined separately to estimate the resulting asymmetric structures at the sea surface and standard 700 mb reconnaissance flight level the surface asymmetry amplitude is on average around 50 smaller than found at flight level and while the asymmetry amplitude grows in proportion to storm translation speed at the flight level no significant growth at the surface is observed contrary to conventional assumption however a significant upwind storm motion relative phase rotation is found at the surface as translation speed increases while the flight level phase remains fairly constant after removing the estimated impact of storm motion on the asymmetry a significant residual shear direction relative asymmetry is found particularly at the

receiver function analysis of the crust and upper mantle from the north german basin to the archaean baltic shield summary two passive seismic experiments have been carried out across the trans european suture zone tesz from northern germany to southern sweden tor and across the proterozoicarchaean suture in finland svekalapko to improve our understanding of the processes involved in the creation of the european continent teleseismic earthquakes recorded by the two networks and stations of the grsn and geofon permanent networks have been used for studies of the crust mantle and upper mantle seismic discontinuities with the receiver function method along the tor network the depth to the moho increases from 30 km at the southern edge of the profile to 40 km at the elbe line between the elbe line and tesz the moho branches off and whereas the deeper branch continues at 40 km depth to the tesz a second branch appears at 30 35 km depth the upper branch descends north of the tesz to below 55 km under the northern end of the tor profile the crustal thickening north of the tesz is accompanied by an increase in average vp vs values appearance of intracrustal conversion zones and north dipping features which we interpret as remnants of the subduction and subsequent collision between avalonia and baltica in southern finland beneath the svekalapko network the moho starts in the south at the depth of 40 45 km plunges to about 65 km depth south of the archaean proterozoic suture this deepening of the moho is coincident with a north dipping intracrustal structure apparently related to the subduction and collision and of the proterozoic and archaean provinces in proterozoic north of the line of the suture the moho rises smoothly to 45 50 km depth in the archaean province along the tor profile 410 and 660 discontinuities were hard to detect however manyfold stacking of receiver functions revealed that the conversions from the two discontinuities arrive more or less according to iasp91 predicted time across the svekalapko network 410 and 660 discontinuities arrive markedly earlier than iasp91 theoretical arrival times in particular north of the archaean proterozoic suture in finland the 410 and 660 km conversions arrive about 2 s earlier indicating about 5 per cent higher average upper mantle velocities and lower temperatures than what iasp91 global model predicts

shear forced vertical circulations in tropical cyclones 1 the forced secondary circulation fsc by the vertical shear of horizontal winds is isolated from the latent heating and friction fscs associated with a model simulated hurricane vortex this is achieved by use of a newly developed potential vorticity inversion and quasi balanced vertical motion equations system results show that latent heating forces intense updrafts in the eyewall and slow subsidence in the eye whereas the friction fsc is similar to that of the ekman pumping with the peak ascent occurring near the top of the boundary layer in the eye in contrast when an environmental westerly shear is superposed with an axisymmetric balanced vortex an anticlockwise fsc appears across the inner core region with the rising motion downshear and easterly sheared horizontal flows in the vertical the resulting horizontal flows act to reduce the influence of the vertical shear inside the storm by as much as 30 40 thus opposing the destructive roles of the vertical shear

idealized tropical cyclone responses to the height and depth of environmental vertical wind shear abstractthree sets of idealized cloud resolving simulations are performed to investigate the sensitivity of tropical cyclone tc structure and intensity to the height and depth of environmental vertical wind shear in the first two sets of simulations shear height and depth are varied independently in the third set orthogonal polynomial expansions are used to facilitate a joint sensitivity analysis despite all simulations having the same westerly deep layer 200 850 hpa shear of 10 m s 1 different intensity and structural evolutions are observed suggesting the deep layer shear alone may not be sufficient for understanding or predicting the impact of vertical wind shear on tcs in general vertical wind shear that is shallower and lower in the troposphere is more destructive to model tcs because it tilts the tc vortex farther into the downshear left quadrant the vortices that tilt the most are unable to precess upshear and realign resulting in their failure to intensify shear height appears to

the moho depth distribution in fennoscandia and the regional tectonic evolution from archean to permian times abstract from a variety of seismic refraction and reflection profiling results a new detailed moho depth map for the fennoscandian part of the baltic shield has been compiled a complementary crystalline crustal thickness map was compiled for denmark the skagerrak sea offshore western norway and adjacent areas where sedimentary strata reach maximum thicknesses of 10 km and even more these maps are discussed in relation to tectonic evolution and crustal ages of fennoscandia seismic velocities bouguer gravity and seismicity areas deviating from the proposed age thickness relationships are the kola peninsula archean and the oslo rift permian the average crustal thickness in the former area is around 44 km while the latter area is associated with a moho elevation of 3 5 km maximum crustal thicknesses in excess of 50 km have been found in southwestern and central finland and correlate with a crust of proterozoic age the caledonides of western norway do not exhibit as elsewhere a crustal root sub moho p n and s n seismic velocities are relatively small in that area and bouguer gravity values are strongly negative intracrustal p velocity variations do not seem to reflect geological age or specific tectonic features although the seismicity is moderate in fennoscandia most of the earthquake activity and in particular the largest earthquakes are confined to areas where the crustal thinning is most pronounced

a study of the interaction between typhoon francisco 2013 and a cold core eddy part i rapid weakening abstracttyphoon francisco 2013 experienced unusually rapid weakening rw with its maximum surface wind decreasing by 45 kt 1 kt 0 51 m s 1 over 24 h as measured from the satellite derived ad

simultaneous velocity and interface tomography of normal incidence and wide aperture seismic traveltime data summary a tomographic inversion technique that inverts traveltimes to obtain a model of the subsurface in terms of velocities and interfaces is presented it uses a combination of refraction wide angle reflection and normal incidence data it simultaneously inverts for velocities and interface depths and it is able to quantify the errors and trade offs in the final model the technique uses an iterative linearized approach to the non linear traveltime inversion problem the subsurface is represented as a set of layers separated by interfaces across which the velocity may be discontinuous within each layer the velocity varies in two dimensions and has a continuous first derivative rays are traced in this medium using a technique based on ray perturbation theory and two point ray tracing is avoided by interpolating the traveltimes to the receivers from a roughly equidistant fan of rays the calculated traveltimes are inverted by simultaneously minimizing the misfit between the data and calculated traveltimes and the roughness of the model this smoothing regularization stabilizes the solution of the inverse problem in practice the first iterations are performed with a high level of smoothing as the inversion proceeds the level of smoothing is gradually reduced until the traveltime residual is at the estimated level of noise in the data at this point a minimum feature solution is obtained which should contain only those features discernible over the noise the technique is tested on a synthetic data set demonstrating its accuracy and stability and also illustrating the desirability of including a large number of different ray types in an inversion

a statistical analysis of the effects of vertical wind shear on tropical cyclone intensity change over the western north pacific abstractthe effect of vertical wind shear vws between different pressure levels on tc intensity change is statistically analyzed based on the best track data of tropical cyclones tcs in the western north pacific wnp from the joint typhoon warning center jtwc and the ecmwf interim reanalysis era interim data during 1981 2013 results show that the commonly used vws measure between 200 and 850 hpa is less representative of the attenuating deep layer shear effect than that between 300 and 1000 hpa moreover the authors find that the low level shear between 850 or 700 and 1000 hpa is more negatively correlated with tc intensity change than any deep layer shear during the active typhoon season whereas deep layer shear turns out to be more influential than low level shear during the remaining less active seasons further analysis covering all seasons exhibits that a tc has a better chance to intensify than to decay when the deep layer shear is lower than 7 9 m s 1 and the low level shear is below

mineral chemistry constraints on the evolution of the 1 88 1 87 ga post kinematic granite plutons in the central finland granitoid complex abstract a suite of post kinematic 1 88 1 87 ga silicic plutons crosscut 1 89 1 88 ga synkinematic granitoids in the central finland granitoid complex cfgc in south central finland the plutons range from biotite hornblende quartz monzonite to syenogranite and include pyroxene and olivine bearing varieties mineral chemical data on feldspars biotite amphibole pyroxenes olivine and oxides of the post kinematic plutons are presented the data are interpreted to show that these plutons register 1 a considerable range in pressure from 2 4 kbar amphibole barometry to 5 7 kbar olivine pyroxene barometry 2 temperatures mostly reflecting resetting during cooling 450 800 c quilf thermometry and 3 low fo2 log fo2 fmq 0 3 to 1 5 quilf equilibria in particular plutons with olivine and pyroxene bearing margins and amphibole dominated central parts record progressive oxidation and hydration upon cooling shifting from the quilf equilibrium toward kuilb the post kinematic granites can be considered post collisional in regard to compressional events in the cfgc and display many of the characteristics of the anorogenic 1 6 ga rapakivi granites further south they were presumably derived from a deep and dry crustal source like the rapakivi granites

geophysical interpretation of the crustal and upper mantle structure in the wiborg rapakivi granite area southeastern finland abstract the rapakivis in southeastern finland and russian karelia cover a total area of more than 20 000 km 2 and comprise the proterozoic 1 6 1 3 ga anorogenic wiborg ahvenisto suomenniemi and onas batholiths and associated mafic rocks a model of the crustal and upper mantle structure in this area based on gravity aeromagnetic deep seismic sounding and petrophysical data is presented the average density 2625 kg m 3 of the batholiths is lower than that of the surrounding svecofennian rocks by about 80 kg m 3 the density histogram of the rapakivi granites is divided into two normally distributed components with mean densities of 2625 kg m 3 major and 2690 kg m 3 minor respectively there are related local gravity anomalies the susceptibility histogram of the rapakivi granites is decomposed into five log normally distributed components the two major components have mean susceptibilities of 165 and 1305 10 6 si units the former component 40 is virtually paramagnetic and the latter 60 is weakly ferromagnetic the two components with mean susceptibilities of 6000 and 13 5000 10 6 si units constitute only 3 of all the samples associated gabbro anorthosites also have high susceptibilities 1450 30 370 10 6 si units these ferrimagnetic rocks cause noticeable local aeromagnetic anomalies an extensive bouguer anomaly low is associated with the batholiths a pronounced regional high surrounds this low the range of values is nearly 60 mgal the anomaly pattern is primarily the result of superposition of the gravity low which is due to the relatively low density upper and middle crust onto the broader gravity high that is due to the uplifted moho according to the published deep seismic sounding results the crust is 41 km thick in the rapakivi region thus it is 6 20 km thinner than to the west north and south of the rapakivi batholiths the refraction model also implies a 6 km thick high velocity body at a depth of 10 km this body has a high v p v s ratio and is interpreted as gabbro anorthosite the magnetic anomaly values in the rapakivi area are slightly higher than those in the surrounding schist areas but lower than the values in the metavolcanic belt to the west within the wiborg batholith there is a zone of positive regional magnetic anomalies with a separate well defined magnetic high of about 400 nt in the western part this anomaly is interpreted as a pipe like magnetic body with an abnormally strong magnetization the upper surface of the body lies at depths between 12 and 15 km the body extends from the upper to the lower crust the model derived from geophysical data supports a proterozoic mantle upwelling which provided excess heat to cause uplift and partial melting of both the upper mantle and the lower crust partial melting of the upper mantle produced intrusions of gabbro anorthosites and diabases while extensive partial melting of the lower crust produced rapakivi magmas and caused their emplacement into the upper crust

effects of vertical wind shear and storm motion on tropical cyclone rainfall asymmetries deduced from trmm abstract vertical wind shear and storm motion are two of the most important factors contributing to rainfall asymmetries in tropical cyclones tcs global tc rainfall structure in terms of azimuthal distribution and asymmetries relative to storm motion has been previously described using the tropical rainfall measuring mission microwave imager rainfall estimates the mean tc rainfall distribution and the wavenumber 1 asymmetry vary with storm intensity and geographical location among the six oceanic basins this study uses a similar approach to investigate the relationship between the structure of tc rainfall and the environmental flow by computing the rainfall asymmetry relative to the vertical wind shear the environmental vertical wind shear is defined as the difference between the mean wind vectors of the 200 and 850 hpa levels over an outer region extending from the radius of 200 800 km around the storm center the wavenumber 1 maximum rainfall asymmetry is downshear left right in the northern

a teleseismic study of the lithospheric structure across the ladoga bothnian bay zone in finland abstract in order to study teleseismic arrivals times across the ladoga bothnian bay zone a proposed suture zone that separates the karelian region 2 7 ga from the svecofennian region 1 8 ga a seismic array of 22 event recorders was deployed along the sveka profile in central finland the p travel time delays are shown to vary by less than 0 2 s along the profile and consistent delay patterns are observed for the various earthquakes the travel time delays delineate zones that appear to correlate with different geological terrains a 2 d inversion of the data yields a tomographic image of the crust and lithosphere across the ladoga bothnian bay zone where 1 velocity variations are resolved the southwestern proterozoic crust is slower 0 15 s than the northeastern archean crust in agreement with a relatively thinner about 6 km archean crust a subcrustal lower velocity 0 8 dome like structure is present beneath the kuhmo block northern part of the profile and is bordered by a southwest dipping higher velocity 0 8 body that seems to connect to the surface trace of the kuhmo suomussalmi greenstone belt

evidence for early proterozoic plate tectonics from seismic reflection profiles in the baltic shield plate tectonics provides the linking framework for all tectonic and magmatic activity seen today but it is not known when plate tectonics first developed on earth new deep seismic reflection and

reservoir sedimentation ii reservoir desiltation and long term storage capacity during the past 30 years china has implemented structural and operational procedures to maximize sediment discharge from the impounded reaches of rivers thereby reducing arresting or reversing reservoir sedimentation at many sites hydraulic methods used in china to preserve reservoir capacity are outlined in this paper including sediment routing during floods sediment flushing during floods emptying and flushing and density current venting a method to compute retrogressive erosion during the drawdown of a reservoir is developed and an approximate method for estimating the amount of sediment that can be vented from a reservoir as a density current is proposed the computed values are compared with field data field data on the floodplain slope formed during flood season and the bottom slope of the main channel formed during nonflood season are analyzed empirical formulas for both slopes are presented for estimating long term storage capacity

a quikscat climatology of tropical cyclone size 1 quikscat data of near surface wind vectors for the years 1999 2008 are used to create a climatology of tropical cyclone tc size defined as the radius of vanishing winds the azimuthally averaged radius of 12 ms 1 wind r12 is calculated for a subset of tcs n 2154 whose centers of circulation were clearly identifiable via subjective analysis of the quikscat analyzed wind field the outer radius r0 is determined from r12 using an outer wind structure model that assumes no deep convection beyond r12 the global median values of r12 and r0 are 197 km and 423 km respectively with statistically significant variation across ocean basins the global distribution of r12 is found to be approximately log normal the distribution of r0 is quantitatively much closer to log normal and the improvement in fit between r12 and r0 is attributed to the combined effect of the nature of the model employed and the paired distributions of r12 and f moreover the normalization employed by dean et al 2009 is found to weaken rather than improve the log normal fit finally within a given storm both r12 and r0 tend to expand very slowly with time early in the storm lifecycle and then becomes quasi constant though significant variance exists across storms

tropical cyclone motion and evolution in vertical shear abstract the motion and the evolution of tropical cyclone like vortices in an environmental flow with vertical shear are investigated using a baroclinic primitive equation model the study focuses on the fundamental dynamics of a baroclinic vortex in vertical shear the influence of vortex structure and the role of diabatic heating the results show that the initial response of the vortex to the vertical shear is to tilt downshear as soon as the tilt develops the upper level anticyclonic and lower level cyclonic circulations begin to interact with each other as a result of these interactions the tilted axis of the vortex reaches a stable state after an initial adjustment which varies with the structure of the vortex its environmental flow shear and the cumulus convective heating the motion of an adiabatic vortex in vertical shear is controlled by both the steering of the environmental flow and vertical coupling mechanisms most of the vortices move with the environmental flow at about 650 hpa or

interactions between simulated tropical cyclones and an environment with a variable coriolis parameter abstract numerical simulations of tropical cyclones are performed to examine the effects of a variable coriolis parameter on the structure and intensity of hurricanes the simulations are performed using the nonhydrostatic fifth generation pennsylvania state university national center for atmospheric research mesoscale model using a 5 km fine mesh and fully explicit representation of moist processes when a variable conolis parameter f environment is applied to a mature tropical cyclone a persistent north northwesterly shear develops over the storm center as a result of an interaction between the primary circulation of the storm and the gradient in absolute vorticity as a result the variable f storm quickly develops a persistent wavenumber 1 asymmetry in its inner core structure with upward motion and rainfall concentrated on the left side of the shear looking downshear in agreement with earlier studies in comparison the constant f storm develops weak transient asymmetries in structure that are

on the initial development of asymmetric vertical motion and horizontal relative flow in a mature tropical cyclone embedded in environmental vertical shear in this paper the authors focus on the initial development of asymmetric vertical motion and horizontal relative flow in a mature tropical cyclone tc embedded in an environmental vertical shear the fully compressible nonhydrostatic tc model was used to perform a series of numerical experiments with a mature tc with different intensities embedded in shear with different magnitudes and different vertical profiles results show that the development of both the wavenumber 1 asymmetric vertical motion and horizontal relative flow for a tc embedded in vertical shear is quite sensitive to both the magnitude and the vertical profile of wind shear as well as the intensity of the tc itself diagnostic analysis based on the quasi balanced potential vorticity inversion indicates that the balanced dynamics can only explain a small portion of the asymmetric vertical motion and relative flow the unbalanced processes contribute predominantly to the developmentoftheasymmetricflowinthesimulations itisshownthattheeyewallofamaturetcplaysarole somewhat like a material cylinder embedded in an environmental flow with vertical shear the interaction between the environmental shear and the eyewall produces vertical gradient of convergence divergence of horizontal wind around the lateral edge of the eyewall this forces much stronger asymmetric vertical motion than the balanced processes do and drives significant horizontal relative divergent flow over the storm core which opposes vertical shear and reduces the vertical tilt of the storm axis in addition the budget analysis for the axisymmetric tangential wind demonstrates that the asymmetric flow plays a dominant role in weakening the storm top down

a statistical perspective on wind profiles and vertical wind shear in tropical cyclone environments of the northern hemisphere abstracta statistical analysis of tropical cyclone tc environmental wind profiles is conducted in order to better understand how vertical wind shear influences tc intensity change the wind profiles are computed from global atmospheric reanalyses around the best track locations of 7554 tc cases in the northern hemisphere tropics mean wind profiles within each basin exhibit significant differences in the magnitude and direction of vertical wind shear comparisons between tc environments and randomly selected non tc environments highlight the synoptic regimes that support tcs in each basin which are often characterized by weaker deep layer shear because weaker deep layer shear may not be the only aspect of the environmental flow that makes a tc environment more favorable for tcs two new parameters are developed to describe the height and depth of vertical shear distributions of these parameters indicate that in both tc and non tc environments vertical shear most frequently occurs in shallow layer

a lagrangian trajectory view on transport and mixing processes between the eye eyewall and environment using a high resolution simulation of hurricane bonnie 1998 the transport and mixing characteristics of a large sample of air parcels within a mature and vertically sheared hurricane vortex are examined data from a high resolution 2 km horizontal grid spacing numerical simulation of real case hurricane bonnie 1998 are used to calculate lagrangian trajectories of air parcels in various subdomains of the hurricane namely the eye eyewall and near environment to study the degree of interaction transport and mixing between these subdomains it is found that 1 there is transport and mixing from the low level eye to the eyewall that carries air possessing relatively high values of equivalent potential temperature e which can enhance the efficiency of the hurricane heat engine 2 a portion of the low level inflow of the hurricane bypasses the eyewall to enter the eye and this air both replaces the mass of the low level eye and lingers for a sufficient time order 1 h to acquire enhanced entropy characteristics through interaction with the ocean beneath the eye 3 air in the mid to upper level eye is exchanged with the eyewall such that more than half the air of the eye is exchanged i n5hi nthis case of a sheared hurricane and 4 that one fifth of the mass in the eyewall at a height of 5 km has an origin in the mid to upper level environment where e is much less than in the eyewall which ventilates the ensemble average eyewall e by about 1 k implications of these findings for the problem of hurricane intensity forecasting are briefly discussed

a tomographic crustal velocity model of the central fennoscandian shield summary in this paper local seismic tomographic method is used to find the terrane distribution within the central parts of the accretionary svecofennian orogen this study presents a crustal pwave velocity model and for the first time the s wave velocity and vp vs ratio model of svekalapko area that is 700 800 km 2 in southern and central finland the 3 d model is presented as p and s wave velocity as well as vp vs ratio depth slices and vertical sections the data set comprised of several subsets of crustal pg and sg wave traveltime data from local events recorded by the svekalapko seismic tomography array in 1998 1999 from older controlled source shots recorded at portable stations as well as at permanent stations and from non controlled chemical explosions recorded at permanent seismic stations from 300 local explosions a total of 10 404 pg wave and 9361 sg wave arrival times were inverted to create independent 3 d vp and vs tomographic models from which the vp vs ratio was calculated according to sensitivity tests the optimal horizontal resolution of recognizable velocity structures in the central study area is at least 60 km down to depths of 40 km in the final model the seismic velocities vary smoothly the lateral variations are larger for vp 5 9 6 6 km s 1 than for vs 3 5 3 8 km s 1 in the upper 20 km of the crust at depths of 20 40 km vp varies from 6 5 to 7 2 km s 1 and vs from 3 7 to 4 1 km s 1 the vp vs ratio varies spatially more distinct than p and s wave velocities usually from 1 70 to 1 74 in the upper crust and from 1 72 to 1 78 in the lower crust schist belts and their continuations at depth are associated with lower velocities and lower vp vs ratios vp 6 2 6 8 km s 1 vs 3 6 3 9 km s 1 vp vs 1 68 1 73 than the granitoid areas vp 6 3 7 4 km s 1 vs 3 6 4 2 km s 1 vp vs 1 72 1 78 the svecofennian orogen was accreted from crustal blocks ranging in size from 100 100 km 2 to 200 200 km 2 in cross sectional area the intervening sedimentary belts have ca 0 2 km s 1 lower p and s wave velocities and ca 0 04 lower vp vs ratios tomographic model supports the idea that the thick svecofennian crust was accreted from several crustal terranes some hidden and that the crust was later modified by intra and underplating

interannual shift of the tropical upper tropospheric trough and its influence on tropical cyclone formation over the western north pacific abstractthe east west migration of the tropical upper tropospheric trough tutt on the interannual time scale and its influence on tropical cyclone tc formation over the western north pacific wnp is investigated in this study climatologically the tutt can be identified from 100 to 400 hpa with a relative vorticity maximum between 150 and 200 hpa in addition to the strong westerly vertical wind shear in the south flank of the tutt this study shows that the cold core system is associated with low relative humidity and subsidence to the east of the trough axis as a result the tc formation is enhanced suppressed in the eastern portion of the wnp when the tutt shifts eastward westward on the interannual time scale the interannual tutt shift is closely associated with the sst anomalies in the central and eastern tropical pacific or enso phases the warm cold phase of enso corresponds to the eastward westward shift of the tutt the physical factors found to be responsible for the influence of

a numerical study of hurricane erin 2001 part ii shear and the organization of eyewall vertical motion a high resolution numerical simulation of hurricane erin 2001 is used to examine the organization of vertical motion in the eyewall and how that organization responds to a large and rapid increase in the environmental vertical wind shear and subsequent decrease in shear during the early intensification period prior to the onset of significant shear the upward motion in the eyewall was concentrated in small scale convective updrafts that formed in association with regions of concentrated vorticity herein termed mesovortices with no preferred formation region around the eyewall asymmetric flow within the eye was weak as the shear increased an azimuthal wavenumber 1 asymmetry in storm structure developed with updrafts tending to occur on the downshear to downshear left side of the eyewall continued intensification of the shear led to increasing wavenumber 1 asymmetry large vortex tilt and a change in eyewall structure and vertical motion organization during this time the eyewall structure was dominated by a vortex couplet with a cyclonic anticyclonic vortex on the downtilt left downtilt right side of the eyewall and strong asymmetric flow across the eye that led to strong mixing of eyewall vorticity into the eye upward motion was concentrated over an azimuthally broader region on the downtilt side of the eyewall upstream of the cyclonic vortex where low level environmental inflow converged with the asymmetric outflow from the eye as the shear diminished the vortex tilt and wavenumber 1 asymmetry decreased while the organization of updrafts trended back toward that seen during the weak shear period based upon the results for the erin case as well as that for a similar simulation of hurricane bonnie 1998 a conceptual model is developed for the organization of vertical motion in the eyewall as a function of the strength of the vertical wind shear in weak to moderate shear higher wavenumber asymmetries associated with eyewall mesovortices dominate the wavenumber 1 asymmetry associated with the shear so that convective scale updrafts form when the mesovortices move into the downtilt side of the eyewall and dissipate on the uptilt side under strong shear conditions the wavenumber 1 asymmetry characterized by a prominent vortex couplet in the eyewall dominates the vertical motion organization so that mesoscale ascent with embedded convection occurs over an azimuthally broader region on the downtilt side of the eyewall further research is needed to determine if these results apply more generally

generation of new continental crust and terrane accretion in southeastern alaska and western british columbia constraints from p and s wave wide angle seismic data accrete abstract the accrete study addresses the question of continental assemblage in southeastern alaska and western british columbia through accretion of exotic terranes and generation of new crust by magmatic addition in a former continental arc we present results of wide angle p and s wave seismic interpretation of a 300 km long marine land seismic line across the contacts between accreted terranes and coast mountains additional constraints on the model are obtained from correlation with geologic mapping our results indicate that the coast shear zone csz is a nearly vertical fault zone probably related to a transpressive regime west of the csz the mid cretaceous 90 ma thrust belt is rooted in the deep crust and is truncated by the csz from the interpretation of the imaged sub vertical reflecting zones we infer the positions of the alexander wrangellia terrane boundary awb and of tertiary extensional grabens within dixon entrance near its intersection with the profile the observed values of vp and vp vs in the lower crust of the alexander terrane are similar to those of oceanic crust and distinctly different from the coast mountains batholith cmb to the northeast the crust under the cmb 32 km is thinner than the average continental crust and the moho is sharp 200 m and highly reflective the low velocity mantle 7 9 km s suggests high temperature consistent with the stability of garnet in mafic rocks in the lower crust the lower crustal velocity of 6 9 km s supports a lower crust composed of interlayered garnet pyroxene granulite and quartzofeldspathic restite related to batholith generation the crustal section under the cmb is seismically identical to the lower two thirds of normal crust heated and inflated by intrusions of tonalite and gabbro interlayered with restites from batholith generation and uplifted during exhumation

a numerical study on rapid intensification of typhoon vicente 2012 in the south china sea part ii roles of inner core processes abstractin part i of this study the role of environmental monsoon flow in the onset of rapid intensification ri of typhoon vicente 2012 was discussed in this part ii key inner core processes that effectively resist environmental vertical wind shear during ri onset are investigated the convective precipitation shield cps embedded in the downshear convergence zone plays a vital role in preconditioning the tropical cyclone tc vortex before ri the cps induces a mesoscale positive vorticity band pvb characterized by vortical hot tower structures upstream and shallower structures 4 km downstream multiple mesovortices form successively along the pvb and are detached from the pvb at its downstream end rotating cyclonically around the tc center the sufficient amount of vorticity anomalies in the pvb facilitates the upscale growth of a mesovortex into a reformed inner vortex which eventually replaces the parent tc vortex i e downshear reformation leading to ri onset the timing of downshe

structure of the crust and uppermost mantle beneath southern finland revealed by analysis of local events registered by the svekalapko seismic array abstract in 1998 1999 a large scale seismic array was deployed in finland as a part of the europrobe svekalapko subproject involving 14 european universities and research institutes the objective of the project was to map the deep lithosphere structure and thickness beneath the fennoscandian shield by means of teleseismic events in addition about 580 local seismic events were registered during the data acquisition period among them only eight local earthquakes were recorded the rest being quarry blasts from mining sites in russia finland estonia and sweden in this study we present the analysis of the seismic wave field from the strongest local events registered by the majority of the stations of the svecofennian karelian lapland kola transect svekalapko array with the aim of mapping the structure of the upper mantle beneath the array for this purpose we selected the events corresponding to a single source type and compared these recordings with those from wide angle reflection and refraction experiments in the area to identify the regional phases the record sections of selected events demonstrate strong reflections pmp from the moho boundary the refracted pn phases can be seen as first arrivals at distances of about 200 400 km from the source at offsets of about 400 800 km phases reflected from inhomogeneities in the uppermost mantle p1 and double reflections from the moho boundary pmppmp were recorded results from 2d forward ray trace modeling of reflected and refracted p waves along four profile swathes from svekalapko stations demonstrate that the mantle reflections originate from two different groups of boundaries beneath the array one group of phases arrive from subhorizontal and gently dipping reflectors below the moho boundary at a depth of 70 90 km while the other group are phases originating from a depth of 100 to 130 km based on the irregular character of the first group of reflections their different spatial orientation and correlation with the moho offsets we interpret the boundaries of this group as relicts of ancient subduction and collision processes the second group of reflections can be explained by a transition from mechanically strong to mechanically weak lithosphere

constraints on the composition of the crust and uppermost mantle in northwestern canada vp vs variations along lithoprobe s snorcle transect shear wave seismic data recorded along four profiles during the snore 97 1997 slave northern cordillera refraction experiment refraction wide angle reflection experiment in northwestern canada are analyzed to provide s wave velocity vs models these are combined with previous p wave velocity vp models to produce cross sections of the ratio vp vs for the crust and upper mantle the vp vs values are related to rock types through comparisons with published laboratory data the slave craton has low vp vs values of 1 68 1 72 indicating a predominantly silicic crustal composition higher values 1 78 for the great bear and eastern hottah domains of the wopmay orogen imply a more mafic than average crustal composition in the western hottah and fort simpson arc values of vp vs drop to 1 69 these low values continue westward for 700 km into the foreland and omineca belts of the cordillera providing support for the interpretation from coincident seismic reflection studies that much of the crust fro

rapid weakening of typhoon chan hom 2015 in a monsoon gyre a monsoon gyre is a low frequency cyclonic circulation over the western north pacific which plays important roles in tropical cyclone formation and motion this study shows that the interaction between a monsoon gyre and a tropical cyclone can lead to a sudden weakening of the tropical cyclone through an observational analysis of typhoon chan hom 2015 typhoon chan hom 2015 initially moved westward along 10 n and sharply turned northeastward in the philippine sea at 0000 utc 3 july its intensity decreased by 10 3 m s 1 within 12 hours during the sudden northward turn such a rapid weakening event was failed to predict in all of the operational forecasts it is found that chan hom was coalescing with a large scale monsoon gyre on the intra seasonal 15 30 day time scale while it experienced the sudden track change and rapid intensity weakening the weak and loosely organized convection on the eastern side of the monsoon gyre at 1200 utc 2 july rapidly enhanced into the well organized convection within 6 hours the strong convection maintaining from 1800 utc 2 july to 0600 utc 3 july enhanced inflows outside the radius of 500 km from the tropical cyclone center which prevented the inward transportation of mass and moisture into chan hom leading to the collapsing of the eastern part of the eyewall as a result chan hom underwent the rapid weakening even under a large scale environment favorable for intensification the study suggests that the rapid weakening of a tropical cyclone can result from its interaction with a monsoon gyre