structural outline of a tertiary basement cored uplift inversion structure in western spitsbergen svalbard kinematics and controlling factors the tertiary fold and thrust belt of spitsbergen can be divided into a western basement involved fold thrust stack and a central eastern foreland fold and thrust belt in western nordenskiold land the first order structure is an ene verging basement cored fold and fault complex involving paleozoic to tertiary strata the northern part reveals an upright monocline geometry of east tilted sedimentary cover units with associated layer parallel to low angle thrusts and folds these structures consist of two populations oriented both parallel to nnw sse and oblique to wnw ese the general structural trend of the fold complex in the central and southern parts of west nordenskiold land the fold complex involves tilted basement cut by steep transverse faults and late normal faults the east limb of the fold complex displays repeated basement and paleozoic strata orustdalen formation in its core and mesozoic triassic strata influenced by map scale chevron folds and two decollement levels all located above an eastward rotated major detachment fault the kleivdalen thrust establishing fold fault relations includes a three stage structural history in the fold complex as follows 1 a phase of early nne ssw shortening associated with wnw ese folds and thrusts and 2 a dominant ene wsw basement involved shortening leading to the first order nnw sse striking fold complex followed by 3 approximately e w extension the resulting structures and structural variability along strike as well as across strike appear to have been controlled by basement and carboniferous basin structures underlying the permian cretaceous platform strata restored stratigraphic sections based on thrust repetition of basement and cover e g within a type section of the carboniferous orustdalen formation support such an interpretation a tentative inversion tectonic model reproduces the position s of local and major thrust ramps and associated folds as a result of inheritance from carboniferous basin structures

evolution of the central tertiary basin of spitsbergen towards a synthesis of sediment and plate tectonic history abstract the central tertiary basin of spitsbergen developed east of a strike slip boundary between the eurasian and greenland plates in response to the initiation of rifting and later seafloor spreading in the norwegian greenland sea using a new plate model for the opening of the north atlantic we attempt to relate the sediment history of the central tertiary basin to its plate tectonic framework and suggest a basin development in four phases the central tertiary basin was formed in the early paleocene during a right lateral strike slip phase after the plate boundary between greenland and svalbard had jumped eastward to the hornsund fault zone phase 1 the onset of seafloor spreading between greenland and eurasia and a drastic counterclockwise change in spreading direction between greenland and north america after chron 25 late paleocene induced compression dominated transpression between greenland and svalbard until chron 24 lower eocene phase 2 the first sedimentary evidence for tectonic uplift along the strike slip zone is found in a wedge shaped delta fan in the northwestern part of the basin strike slip dominated transpression prevailed from chron 24 to chron 21 lower middle eocene contemporaneous with successive basin narrowing and an eastward migration of the depocenter phase 3 after chron 21 lower middle eocene the relative motion between greenland and svalbard first changed to strike slip terminating the transpressional phase and then to transtension after chron 13 lower oligocene phase 4

interferometric meteor head echo observations using the southern argentina agile meteor radar a radar meteor echo is the radar scattering signature from the free electrons generated by the entry of extraterrestrial particles into the atmosphere three categories of scattering mechanisms exist specular nonspecular trails and head echoes generally there are two types of radars utilized to detect meteors traditional vhf all sky meteor radars primarily detect the specular trails while high power large aperture hpla radars efficiently detect meteor head echoes and in some cases nonspecular trails the fact that head echo measurements can be performed only with hpla radars limits these studies in several ways hpla radars are sensitive instruments constraining the studies to the lower masses and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time these drawbacks can be addressed by developing head echo observing techniques with modified all sky meteor radars such systems would also permit simultaneous detection of all different scattering mechanisms using the same instrument rather than requiring assorted different classes of radars which can help clarify observed differences between the different methodologies in this study we demonstrate that such concurrent observations are now possible enabled by the enhanced design of the southern argentina agile meteor radar saamer the results presented here are derived from observations performed over a period of 12 days in august 2011 and include meteoroid dynamical parameter distributions radiants and estimated masses overall the saamer s head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique

a radio science perspective on long duration meteor trails 1 nonclassical radar meteor echoes or range spread trail echoes rstes lasting from tens of seconds to over 15 min have been a subject of considerable interest and speculation in the community ever since they were first observed in the 1940s using data collected from the jicamarca radio observatory 50 mhz vhf radar in june 2006 we find that many properties of rstes can be explained largely from a radio science perspective on a statistical basis rstes of duration 15 s are observed exclusively from scatterers in the k b k radar wave number b geomagnetic field region apparently as the result of trail evolution parallel to b forming approximately fresnel zone sized scattering regions thus narrowing the scattering pattern this result implies that the initial irregularity structures in the meteor trail exhibit a wide scattering pattern that can be seen from anywhere in the radar beam given sufficient radar sensitivity but once the trail significantly elongates along b it can be detected only from the k b region of the radar this conclusion has far reaching implications to current interpretations of instability development in rstes as the location of the meteoroid trajectory relative to the narrow k b region strongly determines observed rste properties such as onset time relative to the head echo and trail lifetime as functions of altitude that is a rste event viewed by two closely spaced identical radars would have different properties meteoroid size energy and fragmentation as well as radar properties such as frequency beam pattern and absolute sensitivity play obvious roles as well

late cretaceous cenozoic intraplate contractional deformation at the norwegian continental shelf timing magnitude and regional implications abstract contractional structures large anticlines and synclines reverse faults and inverted centres of deposition of assumed late cretaceous cenozoic age are common in cretaceous tertiary basins of the northwestern european margin the similarities in style orientation and timing of these structures are striking the present detailed analysis of one anticline the ormen lange dome of the mid norwegian continental shelf indicates that the total contraction is moderate less than 2 3 and that the analysed anticline has been growing almost continuously since its initiation in eocene till present inversion in the barents sea started already in the late cretaceous this episode is suggested to be related to far field effects of active plate margin processes and transfer of stresses across the plate as a consequence of the sub hercynian and paleocene laramide event of the alpine orogeny the development of co axial structures was facilitated by stress focusing along pre existing high relief n s and ne sw trending fault complexes far field plate tectonic stresses originating mainly from the alpine orogeny seem to have been the most important cause of contractional deformation on the nw european shelf in addition ridge push from the north atlantic spreading may have contributed significantly particularly during the neogene

modeling long duration meteor trails 1 we constructed a model of the plasma evolution of meteor trails in order to simulate high power large aperture radar observations this model follows meteor evolution from ablation and ionization to head echo formation and through non specular trail reflections meteor plasma field aligned irregularities fai result in radar reflections called non specular meteor trails we have updated our model to include the polarizing effects of winds and background electric fields on meteor trail instability this model incorporates existing meteor physics together with knowledge we gained from the simulations such as instability physics and anomalous diffusion comparing results from this model with large radar observations of head echoes and non specular trails shows that we can reproduce many of the observed features such as the detailed altitude profile and duration of head echoes and non specular trails specifically when external electric fields are included in our model the same model predicts both short duration order of 1 s and long duration meteor trails several minutes depending upon the characteristics of the meteoroid and atmosphere the addition of a background e field or wind also reproduces a commonly observed non specular trail feature we call an extended tail where the delay time between head echo and non specular reflection at the lower altitude portion of the trail increases as the meteor gets lower in the atmosphere we also demonstrate a dependence on trail duration with the electron density of the background ionosphere

longitudinal characteristics of spread f backscatter plumes observed with the ear and sanya vhf radar in southeast asia 1 the development of equatorial plasma irregularity plumes can be well recorded by steerable backscatter radars operated at and off the magnetic equator due to the fact that the vertically extended plume structures are tracers of magnetically north south aligned larger scale structures from observations during march 2012 using two low latitude steerable backscatter radars in southeast asia the equatorial atmosphere radar ear 0 2 s 100 3 e dip lat 10 4 s and the sanya vhf radar 18 4 n 109 6 e dip lat 12 8 n the characteristics of backscatter plumes over the two sites separated in longitude by 1000 km were simultaneously investigated the beam steering measurements reveal frequent occurrences of multiple plumes over both radar sites of which two cases are analyzed here the observations on 30 march 2012 show plume structures initiated within the radar scanned area followed by others drifting from the west of the radar beam over both stations a tracing analysis on the onset locations of plasma plumes reveals spatially well separated backscatter plumes with a maximum east west wavelength of about 1000 km periodically generated in longitudes between 85 e and 110 e the postsunset backscatter plumes seen by the sanya vhf radar are found to be due to the passage of sunset plumes initiated around the longitude of ear most interestingly the ear measurements on the night of 21 march 2012 show multiple plume structures that developed successively in the radar scanned area with east west separation of 50 km with however no sunset plasma plume over sanya colocated ionogram measurements show that spread f irregularities occurred mainly in the bottomside f region at sanya whereas satellite traces in ionograms that are indications of large scale wave structures were observed on that night at both stations possible causes for the longitudinal difference in the characteristics of radar backscatter plumes are discussed

interpretation of non specular radar meteor trails 1 radar data of non specular meteor trails shows two clear and consistent features 1 non specular meteor trails are observed from a narrower altitude range than are head echoes and 2 an approximately 20 ms delay between meteor head echoes and trail radar scatter this paper shows that both features can result from meteor trail plasma instability simulations have demonstrated that trails often develop farley buneman gradient drift fbgd waves which become turbulent and generate field aligned irregularities fai plasma stability analysis shows that trails are only unstable within a limited altitude range matching the observed altitudes of non specular trails to within 1 2 km the simulations show that instability develops into turbulence in 20 ms and appears to be the only meteor trail process that can explain both the observed delay between head and trail echoes and generate coherent scatter at both uhf and vhf wavelengths

the margin between senja and spitsbergen fracture zones implications from plate tectonics abstract analysis of multichannel seismic data from the continental margin off svalbard between the senja and spitsbergen fracture zones suggests that the transition between continental and oceanic crust is located at or close to the hornsund fault zone in the late paleocene early eoeene 57 m y the region between svalbard and northeast greenland was subjected to regional shear movements associated with a transform system between the young lofoten greenland basin and the arctic ocean approximately 50 m y ago the spreading axis migrated to the northeast creating a deep basin north of the greenland senja fracture zone forming the passive margin between bear island and 76 5 n north of 76 5 n the regional transform was maintained at the time of the main reorganization of relative plate motion 36 m y the northern margin evolved a continental fragment was possibly cut off from the svalbard margin forming a small microcontinent the microcontinent appears as the submarine ridge which has been associated with the hovgaard fracture zone it is suggested that the sediments west of the hornsund fault zone are not older than eocene in the south and mid oligocene in the north the position of the spreading axis has greatly influenced the margin sedimentation

dispersion experiments in u k coastal waters abstract over the period 1968 to 1999 brixham environmental laboratory carried out dye tracing experiments to determine local mixing conditions at coastal and estuarine sites around the united kingdom results from 25 different locations and from five non u k sites have been analysed to estimate horizontal and vertical mixing coefficients analysis of the data from the 19 sites which had the most complete data sets showed that the minimum lateral dispersion coefficient ranged from 0 003 to 0 42 m2 s 1with a median value of 0 05 m2 s 1 typical vertical diffusion coefficients ranged between 2 0 10 4to 110 0 10 4 m2 s 1and had a median value of 20 0 10 4 m2 s 1 comparisons of the values obtained have been made with mixing coefficients derived from earlier dye tracer studies in the north sea the irish sea and off the eastern seaboard of the u s a a plot of minimum lateral dispersion coefficients against the corresponding vertical diffusion coefficients showed that the results fell into two distinct bands broadly represented by shallow or deep water within each band the lateral mixing coefficients appeared to vary in inverse proportion to the vertical coefficients as would be expected in shear dispersion in which mixing is restricted by the surface and seabed or pycnocline curves representing this variation had different constants of proportionality for the shallow and deep waters this was ascribed to a reduction in the curvature of the velocity profiles in the deep water areas where stronger currents may have reduced the degree of stratification analysis of the full data set has not identified any generally applicable relationship between the mixing coefficients and tidal currents or wind however relationships between these parameters could be found within specific survey areas for example lateral diffusion coefficients in the solent appeared to be correlated with the tidal current amplitude

along strike changes in fault array and rift basin geometry of the carboniferous billefjorden trough svalbard norway abstract the billefjorden fault zone bfz of svalbard norway is a long lived major tectonic lineament with significant influence on the structural style of the northwestern barents shelf the fault zone can be traced for around 2 300 km in an n s direction where it is made up of three major fault strands all dipping 50 70 to the east field and seismic data delineate gradual shifts in displacement between master faults northern odelfjellet balliolbreen and southern dronbreen faults and suggest that two c 20 km long 2 3 km wide relay zones exist along strike the western fault strand consistently has a pre carboniferous reverse character placing basement on top of devonian sedimentary units with a throw estimated at 10 km subsequent carboniferous extensional reactivation of segments of the bfz resulted in formation of the billefjorden trough with a rift basin showing a fairly consistent polarity for its length this suggests a profound control by the older devonian reverse faults on the extensional structural style the billefjorden trough extends for a minimum of 110 km along strike and is 20 30 km wide at the most a gentle north plunge of the basin axis in the south is mirrored by an opposite plunge in the north offering a depth thickness of around 2000 m in the central realm diminishing to 500 m in the south geometries of the trough suggest sedimentary response to fault growth with weak lithologies such as evaporites promoting fault monocline formation and associated lenticular basin geometries on the contrary wedged shaped fill geometries toward major faults is consistent with significant fault movement and growth sequences subsequent mild tertiary reactivation of fault segments of the bfz is suggested by local reverse faults and deep seated anticline syncline pairs

meteor trail diffusion and fields 1 simulations 1 a meteoroid penetrating the earth s atmosphere leaves behind a trail of dense plasma embedded in the lower e upper d region ionosphere while radar measurements of meteor trail evolution have been collected and used to infer meteor and atmospheric properties since the 1950s no accurate quantitative model of trail fields and diffusion exists this paper describes finite element simulations of trail plasma physics applicable to the majority of small meteors unlike earlier research our simulations resolve both the trail and a vast current closure area in the background ionosphere this paper also summarizes a newly developed analytical theory of meteor electrodynamics and shows that our simulations and theory predict nearly identical fields and diffusion rates this study should enable meteor and atmospheric researchers to more accurately interpret radar observations of specular and nonspecular meteor echoes

structural evolution of a frontal ramp section of the west spitsbergen tertiary fold and thrust belt north of isfjorden spitsbergen the geometry and kinematic evolution of a frontal ramp section associated with the tertiary west spitsbergen orogenic belt has been investigated in a small area lappdalen north of isfjorden the previously recognized thrust front corresponds to a complex step or ramp in the position of the sole thrust in the area the sole thrust is localized to the evaporites of the permian gipshuken formation to the west of the footwall ramp whereas to the east it continues as a bedding parallel thrust in triassic shales sassendalen group the area to the west of the footwall ramp is characterized by large scale thrusts and folds involving the permian gipshuken and kapp starostin formations and the lower part of the triassic sassendalen group east of the footwall ramp both permian and triassic strata are sub horizontal and apparently undeformed three major thrust sheets are recognized based on the geometric relationship between folds and faults in the area both fault bend and fault propogation mechanisms of folding are inferred restoration of the kapp starostin formation to its pre deformational state indicates a minimum of 35 shortening structural observations within the sassendalen group in the study area and on dickson land suggest that some of this shortening is transmitted eastwards along one or more bedding parallel thrusts in the sassendalen group

tertiary tectonism and basin inversion of the st jonsfjorden region svalbard abstract deformed basement and cover rocks of the st jonsfjorden area further define the character of spitsbergen s tertiary fold and thrust belt three major thrusts comprise a folded ca n060 e directed foreland propagating thust stack with likely additional subsurface thrust faults the folded vegardbreen robertsonfjellet thrust is the most significant fault in the complex and re emerges in the core of a disrupted synclinal structure in triassic strata shortening across the area indicated from line length restoration is of the order of 13 km differences in stratigraphy between and within thrust sheets indicate the thrust stack initiated along the edge of a westward deepening carbonbiferous basin with a fault step margin and represents basin inversion early structures related to basin formation had a major control on later thrust sheet evolution and the complexity of inversion structures reflects the initial complexity of the basin geometry such basin inversion could characterize the length of the fold and thrust belt the st jonsfjorden structures are primarily contractional and together with areas farther southeast in the fold thrust belt indicate shortening took place perpendicular to the fold belt across much of the length of the evolving margin

tertiary or cretaceous age for spitsbergen s fold thrust belt on the barents shelf several publications propose that main phase fold thrust development on spitsbergen was late cretaceous and not tertiary as previously thought the question of timing is crucial to models for crustal response to transpressive plate motions involvement of tertiary strata in fold thrust structures the sedimentology of the tertiary basin strata and studies of paleo stress field evolution all indicate paleocene to eocene fold thrust development during opening of the norwegian greenland oceanic basin a regional angular unconformity of 1 between paleocene and early cretaceous strata is consistently disconformable to the eye and precludes any significant older deformation in the immediate area pre unconformity deformation was likely strike slip in character and concentrated in the west the proposal for late cretaceous fold thrust belt formation is inconsistent with the geology

cretaceous and tertiary inversion in the bjornoyrenna fault complex south western barents sea a system of half flower like structures folds reverse faults and footwall cut offs is observed adjacent to the bjornoyrenna fault complex in the south western barents sea although the bjornoyrenna fault complex itself is principally an extensional feature with its period of maximum extensional activity in the early cretaceous these structures suggest that the subsidence along the fault complex was interrupted in the hauterivian aptian by left lateral transtension and in the late cretaceous early tertiary by head on inversion both these episodes caused relatively intense deformation and seem to have regional significance consequently the events need to be seen in relation to the plate tectonic development of the south western barents sea

intense winds and shears in the equatorial lower thermosphere measured by high resolution nonspecular meteor radar large horizontal winds and wind shears have been measured in the lower thermosphere by rockets lidars and nonspecular meteor radars this paper describes a detailed analysis of three multihour nonspecular meteor radar data sets collected at the jicamarca radio observatory this provides some of the highest resolution sustained measurements in this part of the atmosphere these show 1 intense wind speeds maintaining 180 m s for half an hour and 160 m s for another half an hour 2 winds structured in layers that move up or more commonly down in the predawn hours at rates of a few kilometers per hour 3 intense wind shears that typically persist at around 50 m s km but in one instance sustains values approaching 100 m s km for a few hours

analysis of fault populations in western spitsbergen implications for deformation partitioning along transform margins mesoscale faults expressed in the paleogene central basin and cretaceous basement along the west spitsbergen orogenic belt are used to define the history of continental deformation associated with the development of the transform system that accompanied the opening of the eurasian basin and the norwegian greenland sea a fundamental change in the orientation of faults from dominantly north south in the basal part of the basin to northeast striking in the upper units broadly correlates with a major shift in plate motion during late paleocene early eocene time the two main populations of faults are interpreted as extension fractures that were variably reactivated as shear fractures and formed in response to north south compression followed by northeast southwest compression paleostress stratigraphy or the analysis of striated faults measured in successive stratigraphic units of the central basin corroborates this interpretation and allows a time sequence of paleostress tensors to be defined results show that a late cretaceous early paleocene north south compression consistent with plate motion was followed by three relatively short lived and regionally limited faulting events leading up to a change in plate motion during late paleocene time post chron 25 major transpressive tectonism followed producing northeast trending fractures that were reactivated as dextral and sinistral faults defining a prolate shape paleostress ellipsoid with a horizontal 1 this regionally reproducible tensor consistent with the prediction of dextral transpression along the paleotransform was probably initiated at approximately the paleocene eocene boundary finally a post early eocene deformation pervasively recorded in the study area by an oblate shape paleostress ellipsoid with horizontal 3 is tentatively correlated with the dextral transtension that characterized the post chron 13 opening of the norwegian greenland sea and eurasian basin this study offers documentation of deformation partitioning during the evolution of a transform margin the late cretaceousearliest paleocene compression associated with the prototransform did not involve substantial partitioning and a north south maximum principal stress pervaded the continental crust away from the transform in contrast the late paleocene eocene transpression reflects total partitioning of deformation along the evolved mature transform margin oblique plate motion was presumably partitioned into a strikeslip zone s offshore whereas the onshore central basin recorded only the orthogonal component of oblique convergence and divergence a pattern similar to modern orogenic belts developed in zones of oblique plate motion

eurekan transpressive deformation in the wandel hav mobile belt northeast greenland 1 besides the w e trending kap cannon thrust zone and harder fjord fault zone the 300 km long and nw se striking wandel hav mobile belt represents the third major fault zone in north greenland structural analyses in several areas of this belt suggest that compressive deformation is characterized by transpressive dextral strike slip kinematics this is demonstrated by a combination of folding around w e axes approximately north and south directed reverse faulting and dextral strike slip displacements along nw se trending fault lines the initial formation of the long linear faults is interpreted to be related to deformational events in late paleozoic triassic jurassic and late cretaceous times due to the lack of structural evidence we assume that deformations led to the generation of extension faults which probably were reactivated during dextral strike slip tectonism it is suggested that dextral transpressive deformation was coeval with n s compression at the harder fjord fault zone and cap cannon thrust zone and took place during eocene eurekan times dextral strike slip tectonism in the wandel hav mobile belt was the result of n s compression due to a general northward movement of the greenland plate as a zone of crustal weakness the belt can be interpreted as the onshore equivalent of the main transcurrent fault zone de geer fault which caused the intracontinental dextral slip of svalbard barents shelf relative to north greenland during early tertiary eurekan times and prior to their separation in this configuration it represents one part of the belt of eurekan deformation which extends from the canadian arctic islands over north greenland to the barents shelf where compressive deformation is recorded in the west spitsbergen fold and thrust belt

horizontal advection and dispersion in a stratified shelf sea the role of inertial oscillations abstract the role played by inertial motions in horizontal dispersion within the thermocline of a broad mid latitude shelf sea is examined through the analysis of a deliberately released dye tracer our analysis is of the horizontal and vertical evolution over 40 h of a dye tracer injected into the seasonally stratified thermocline of the celtic sea on the nw european shelf the inferred diapycnal diffusivity was 1 3 1 5 10 5 m2 s 1 and the radial horizontal diffusivities of the depth integrated dye patch ranged from 1 9 to 4 0 m2 s 1 the inferred vertical diffusivity is in agreement with microstructure based estimates and the depth integrated horizontal diffusivity is broadly in agreement with previous dye release derived estimates made over similar scales and time periods asymmetry in the horizontal evolution of the dye patch was evident we argue that mean shear dispersion was responsible for lateral elongation of the dye patch particularly between hours 23 and 35 after release during which time horizontal diffusivity along the major axis ka exceeded that along the minor axis kb by more than a factor of 10 we further show that along patch shear was predominantly a result of differential advection between a deep residual flow to the south east and an oscillating wind driven surface ekman layer in this region of strong low frequency inertial shear a time dependent model of shear dispersion young et al 1982 was able to account for the observed rate of horizontal dispersion calculated on the target isopycnal surface

low altitude meteor trail echoes 1 we present here the first observations of a new type of meteor echo these low altitude trail echoes late observed almost exclusively below 90 km altitude using the jicamarca research observatory 50 mhz radar exhibit very different features and characteristics from the other well studied and reported meteor trails the specular meteor trails and the range spread trail echoes some of these features include strong altitude dependence low aspect sensitivity and no gap between the head echo and the trail perhaps most importantly almost 80 of the head echoes below 85 km altitude in our data set exhibit late trails the study of these echoes provides valuable insights into the role of diffusion and plasma instabilities in the formation and evolution of meteor trails

on the dispersion and diffusion near estuaries and around islands abstract a series of diffusion experiments using surface drifters were performed in the coastal waters of south western taiwan near a small estuary and around an island two stages or regimes of drifter dispersion can be identified for all experiments a coherent regime in the beginning stage when the drifters remained clustered with little dispersion occurred and a rapid disperse regime in the latter stage when the separation of drifters grew to the order of a few kilometres our results show that near estuaries the extent of the dispersive influence is limited to the tidal excursion distance and the dispersion coefficient is about 12 15 m 2 s 1 on the other hand the dispersion coefficient downstream of an island in a strong flow 1 5 m s 1 can reach a much larger value 45 m 2 s 1 which can be attributed to the enhanced mixing and transport processes due to island wakes theoretical scaling parameters for coastal water flows are also presented to predict the formation of island wakes after applying three different methods to exclude the effects of shear flow the turbulent diffusivities for our experiments amount to 0 2 5 m 2 s 1 analysis of the differential kinematic properties indicates that a close relationship exists among the dispersion diffusion and the effect of shear flow

radar interferometric imaging studies of long duration meteor echoes observed at jicamarca a large number of long duration 15 s meteor echoes were detected at the jicamarca radio observatory on two nights in early august 1990 during an evening electrojet experiment using an interferometric imaging technique we were able to measure a zonal velocity profile for each meteor trail our analysis procedure differs from conventional meteor wind methods in that it provides instantaneous profiles rather than long term average information significant altitudinal and temporal variabilities of the horizontal velocities were noted zonal speeds of up to 100 m s 1 large vertical shears of up to 20 m s 1 km and rapid temporal variations of up to 50 m s 1 over an hour interval were observed spectral analysis indicates the presence and decay of asymmetrical high frequency signal components possible explanations for the observed high frequency components are discussed as are the angle of arrival of and the scattering mechanism responsible for the meteor echoes

discussion on pre ocean opening compression of the northwestern atlantic margin evidence from eastern greenland journal vol 157 2000 707 710 scientific editing by nick rogers h d maher jr s bergh alvar braathen write manby lyberis 2000 argue for a cretaceous palaeocene age and a convergent setting for both the fold structures of the wandel sea basin and for the west spitsbergen fold thrust belt as an alternative to models of decoupling during palaeocene eocene transpressive motions between greenland and the barents shelf in this context we discuss evidence on the timing and kinematics of the west spitsbergen fold thrust belt and constraints on the timing of deformation in the wandel sea basin multiple lines of evidence constraining the timing of fold thrust formation in spitsbergen are discussed in maher et al 1995 and clearly indicate major fold thrust development in the palaeocene eocene space limitations prevent their description here the nature of additional late cretaceous deformation on spitsbergen is another question it is partly constrained by the unconformity at the base of the tertiary sequence which is well exposed in many places and is consistently disconformable to the eye this unconformity involves differential uplift to the north with a regional tilt of a degree or less has a character inconsistent with previous fold thrust development along the islands western margin and can be related to a second pulse within the high arctic large igneous province maher 2001 more recent work confirms a palaeocene eocene age for the spitsbergen contractional structures manby lyberis refer to blythe kleinspehn 1998 as indicating a late cretaceous age for spitsbergen fold thrust belt uplift in their summary figure blythe kleinspehn indicate uplift and erosion of source terranes initiating at 70 ma and continuing until c 43 ma six detailed thermal histories generated from track length modelling of samples taken from the tertiary foreland basin sediments provide particular insight as the authors note three samples with depositional ages of

meteor induced ridge and trough formation and the structuring of the nighttime e region ionosphere 1 when meteor generated plasma trails diffuse into the ionosphere they create large ambipolar electric fields mainly perpendicular to the earth s geomagnetic field b and extending many kilometers from the trail along b these fields will cause ionospheric plasma to collect into ridges extending from the trail along b enhancing the density by as much as a factor of 2 and they will also remove up to 90 of the plasma on each side of the ridge we predict that meteor induced density perturbations may fill as much as 20 of the ionosphere between 95 and 120 km altitude this paper presents simulations and theory to show how meteors produce plasma ridges and troughs we estimate the extent of these as a function of altitude and meteor density this process may explain observations of extensive nighttime e region density structures made by rockets and radars

multi static common volume radar observations of meteors at jicamarca 1 multi static common volume radar mscvr observations have long been considered necessary for meteor observations especially for the study of range spread trail echoes rste we present preliminary results in the form of a case study from the first mscvr observations that were carried out at the jicamarca radar observatory jro in june 2007 a second antenna array of similar sensitivity to a single jro receive module was constructed and operated at carapongo approximately 5 kilometers geomagnetically south of jro the jro main array was used for transmission receiving was done using sub arrays at jro and with the array at carapongo the results provide new insights not only into the aspect sensitivity of rstes but also into the physical structure of the plasma giving rise to these echoes these observations also establish a firmer basis for the modeling of the plasma processes that cause meteor trails to become field aligned

tectonic inversion in the wandel sea basin a new structural model of kilen eastern north greenland the seminunatak kilen in eastern north greenland with its complexly deformed carboniferous cretaceous strata is a key area to understand the tectonic history of the transform plate boundary between eastern north greenland and svalbard detailed 3 d geological mapping from oblique photogrammetry along with limited ground fieldwork and interpretation of previously published data forms the basis for a new structural model of kilen previous structural models interpreted rhombic shaped fault patterns as the evidence for strike slip tectonics these structures are here interpreted to be the result of a post coniacian ne sw extension with nw se trending normal faults followed by later n s compression of presumable paleocene eocene age folding the faults passively and suggesting the presence of a basal detachment furthermore two thrust sheets have been distinguished on kilen a lower kilen thrust sheet and an upper hondal elv thrust sheet separated by a subhorizontal fault the central detachment the style of deformation and the structures described are interpreted as the result of paleocene eocene n s directed compression resulting in basin inversion with strike slip faults only having minor status this indicates that the greenland margin as exposed on kilen and the conjugate svalbard margin in the west spitsbergen fold and thrust belt are more similar than previously anticipated

a comparison of lower thermospheric winds derived from range spread and specular meteor trail echoes 1 interferometry measurements of range spread meteor trail echoes rstes also known as nonspecular echoes have provided new insights into both the irregularity structures in meteor trails and lower thermospheric winds ltws in this study we used trail echoes observed with the newly installed sanya 18 4 n 109 6 e 47 5 mhz vhf coherent radar and the sanya all sky meteor radar to estimate instantaneous zonal and hourly averaged meridional winds from rstes and hourly averaged zonal and meridional winds from large numbers of specular meteor echoes the mean height variations in both the zonal and meridional winds estimated from the rstes were generally consistent with those estimated from specular meteor echoes below 96 km this gives validity to the technique proposed recently by oppenheim et al 2009 and suggests that rste measurements made with a small radar can be used to investigate ltws whereas this had previously been limited to larger radars such as the jicamarca radar however some observations show significant differences in wind magnitude at individual heights at times the results of rste measurements show the presence of an intense westward wind with a speed near 100 ms 1 in contrast the specular meteor zonal winds were generally less than 50 ms 1 on the other hand the meridional drift of rstes derived from the meridional doppler velocity at higher altitudes shows a very poor correlation with the specular meteor meridional wind potential causes for the discrepancy in wind estimates obtained from rste and specular meteor trail echoes are discussed

structural evolution of long duration meteor trail irregularities driven by neutral wind an experiment on spatial domain interferometry observations of meteor trail irregularities at a low latitude location in china was conducted during august 2013 using the sanya vhf coherent radar 18 4 degrees n 109 6 degrees e more than 3 thousand range spread meteor trail echoes rstes were observed among the trail echoes the spatial structure of meteor trail irregularities responsible for a single long duration rste event persisting for similar to 4min was reconstructed this rste was found to be initially generated at 90 115 km altitudes and aligned along the radar beam boresight after about the first minute of the trail lifetime the trail echo appeared only in a narrow altitude range of 94 98 km an analysis on the spatial pattern of the long duration rste showed that the trail irregularities at lower range gates moved away from the region perpendicular to the geomagnetic field the eastward drifts of the rste irregularities were found to decrease with increasing altitude e g from 80 ms 1 at similar to 94 km to 20 ms 1 at similar to 100 km simultaneous horizontal neutral wind measurements made with the fuke all skymeteor radar located north of sanya recorded a similar velocity profile we suggest that the neutral wind could drive the spatial structural evolution of the rste irregularities and help to determine the altitudes where the longest portion of the rste was located

mapping ocean outfall plumes and their mixing using autonomous underwater vehicles this paper reports on our experiences developing methods to survey an ocean outfall discharge plume using an autonomous underwater vehicle auv the mobility of an auv provides a significant advantage in surveying discharge plumes over traditional boat based methods and when combined with optical and oceanographic sensors provides a capability for both detecting plumes and assessing their mixing in both the near and far fields unique to this study is the optical sensing of of the presence of colored dissolved organic matter cdom in the discharge plume for quantitatively assessing the dilution ratio of the plume water this capability is demonstrated for two publicly operated treatment works potws located offshore san diego california that have significantly different environmental settings and operating parameters the first is the south bay ocean outfall sboo operated by the international boundary water commission ibwc whose discharge is located in approximately 30m deep water at a flow rate of 28 million gallons per day mgd the second discharge is the point loma ocean outfall ploo which discharges at approximately 90m with a nominal volume flow rate of 250 mgd the methodologies for planning the auv missions to sample the discharge plume characterizing the plume using the signals measured by the onboard oceanographic and optical sensors and use of those data in predictive models is outline the results suggest that even in variable oceanic conditions properly planned missions for auvs equipped with appropriate sensors can accurately characterize and track ocean outfall plumes with high spatial resolution more effectively than traditional methods

sedimentation in paleogene foreland basin spitsbergen the upper part of the sedimentary succession in the tertiary central trough on spitsbergen comprising the hollendardalen gilsonryggen battfjellet and aspelintoppen formations has been studied with respect to basin formation and basin filling thickness data from the lower marine part of this succession indicate an asymmetric thickening to the west distribution of the several theories on how space was generated to accommodate the sequence tectonic subsidence driven by lithospheric loading from the flanking fold and thrust belt appears to be the most probable the position of the basin between the front of the west spitsbergen fold belt and the adjacent craton suggests a foreland basin setting most of the basin fill constitutes a major regressive sequence gilsonry gen battfjellet and aspelintoppen formations deposited by the eastward progradation of a deltaic system evidence of eastward displacement of the depocenter through time together with the incorporation of the orogenic flank of the basin fill into the deformation suggests cratonward migration of the fold and thrust belt foreland basin couplet the present tertiary central trough represents the uplifted remnants of the latest oligocene foreland basin

day to night variation in meteor trail measurements evidence for a new theory of plasma trail evolution 1 a recent theory of meteor trail plasma diffusion made the prediction that meteors will generate more and longer lasting non specular echoes at night than during the day this letter presents the first evidence of a dramatic day to night difference in non specular meteor trail occurrence rates and their duration these observations were made by the 50mhz radar at the jicamarca radio observatory jro in peru in one 20 minute period starting 95 minutes before sunrise this radar detected 1288 head echoes and 341 trails while a similar time after dawn it measured 1240 head echoes but only 50 trails also the duration of the nighttime trails greatly exceeded the daytime ones this pattern was confirmed by a second experiment in july 2007 this data provides strong evidence that it is necessary to account for the effect of the ionospheric plasma density to explain meteor diffusion

paleostress stratigraphy a new technique for analyzing tectonic control on sedimentary basin subsidence the authors propose a new technique paleostress stratigraphic analysis based on the orientation of minor structures particularly striated fault surfaces in the strata of sedimentary basins these structures are interpreted to be the response to local or regional stress field controlling subsidence of tectonically active basins a method is used that allows multiple stress tensors to be extracted from a fault population by extracting the stress tensor from the youngest part of a stratigraphic sequence and by imposing that same tensor on the underlying rocks one can in principle isolate the faults associated with the youngest tectonic event by reiterating this procedure on progressively older units until the fault data are exhausted a chronologic succession of paleostress tensors during basin subsidence emerges the authors paleostress stratigraphy to the relatively undeformed paleogene central basin of spitsbergen and its underlying cretaceous strata and define five major paleostress tensors coeval with the earliest stages of the opening of the norwegian greenland sea a late cretaceous dextral transpressive regime was probably responsible for the major pre tertiary unconformity and possibly initiated development of the central basin during subsequent sedimentation movement reversed yielding well constrained sinistral shearing during early danian time a composite compressional event followed that themore authors interpret as being coeval with the culmination of folding and thrusting west of the central basin the youngest strata studied record a final extensional event that they correlate with rifting of spitsbergen from greenland less

palaeomagnetic rock magnetic and mineralogical investigations of the lower triassic vardebukta formation from the southern part of the west spitsbergen fold and thrust beltk dudzisz and otherspalaeomagnetism of triassic rocks spitsbergen

svartfjella eidembukta and daudmannsodden lineament tertiary orogen parallel motion in the crystalline hinterland of spitsbergen s fold thrust belt within metamorphic basement rocks of the hinterland of spitsbergen s tertiary fold thrust belt a 35 km long zone of notably deformed carboniferous strata and cretaceous intrusives forms a major orogen parallel lineament from svartfjella to eidembukta to daudmannsodden sedl orientations and geometries of map scale fault duplexes and associated fault plane striae populations of folds and associated cleavage and of tension gashes all indicate orogen parallel motion occurred along the sedl structural analyses indicates three phases 1 ene directed overthrusting 2 sinistral motion with a backthrust component and 3 dextral strike slip motion this history indicates a change from orogen perpendicular to orogen parallel movements orogen parallel movement was likely coeval with orogen perpendicular fold thrust transport to the ene in the foreland a model where dextral transpressive motion between greenland and svalbard was decoupled explains the hinterland foreland difference basement fabric aligned with carboniferous carbonates on the steep foreland face of an antiformal stack provided a through going weak surface a prerequisite for decoupling sinistral orogen parallel motion is explicable by short lived episode of sinistral plate motion or by local wedge extrusion during dextral transpression the evolution of decoupling patterns has significant implications for deducing plate motions from local kinematic and paleostress studies

thrust tectonics on broggerhalvoya and their relationship to the tertiary west spitsbergen fold and thrust belt the tertiary fold and thrust belt on broggerhalvoya is characterized by a ne vergent pile of nine thrust sheets the sole thrust of the pile is located in precambrian phyllites and climbs up section to the northeast four lower thrust sheets consisting predominantly of upper palaeozoic sediments are overlain by two thrust sheets in the central part of the stack which contain a kilometre scale syncline and anticline the fold is cut by juxtaposed thrusts giving rise to the formation of three structurally higher basement dominated thrust sheets a multiple stage kinematic model is proposed including 1 in sequence foreland propagating formation of the lower thrust sheets in response to n s subhorizontal bedding parallel movements 2 a change in tectonic transport to ene and out of sequence thrusting and formation of the kilometre scale fold structure followed by 3 truncation of the kilometre scale fold and stacking of the highest basement dominated thrust sheets by hind ward propagating out of sequence thrusting the strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheets reflecting a temporal change to a more transpressive regime thrusting was followed by 4 n s extension and 5 w e extension comparison of the structural geometry and kinematic evolution of broggerhalvoya with the data reported for the fold belt further south allows us to assume a coeval evolution with the fold belt a latest paleocene early eocene age for the main phase of thrusting is suggested for the west spitsbergen fold and thrust belt the main phases therefore pre date the separation of svalbard and greenland due to right lateral movements along the hornsund fault zone the fold belt s temporal evolution followed by the formation of the forlandsundet graben can be linked with the plate kinematic framework in the span between latest paleocene and middle eocene times

nonspecular meteor trails from non field aligned irregularities can they be explained by presence of charged meteor dust nonspecular meteor echoes have been associated with field aligned irregularities and have been observed at low latitude and midlatitude sites we present observations obtained at high latitudes with range time features that resemble those at lower latitudes however these echoes cannot come from field aligned irregularities since the radar pointing angles are almost parallel to the magnetic field using interferometry we have been able to discriminate space and time features our echoes could be qualitatively explained by the presence of charged dust forming from the meteoric material immersed in a turbulent flow this can lead to a high schmidt number plasma that can sustain meter scale turbulence just as it does for the polar mesospheric summer echoes these rare events require relatively large meteoroids the result emphasizes the importance of charged dust in understanding all long duration nonspecular meteor echoes this dust will extend their diffusion times and will affect temperature estimations from specular echoes

the origin of the west spitsbergen fold belt from geological constraints and plate kinematics implications for the arctic abstract the west spitsbergen fold belt which extends for 300 km along the western margin of svalbard and is up to 80 km wide has much in common with foreland fold and thrust belts the near foreland segment of the fold belt exhibits ramp flat thrust trajectories whilst structurally higher nappes are typified by more listric thrusts higher nappes to the west contain imbricated carboniferous and basement rocks showing that the latter were actively involved in the fold belt deformation and a minimum of 80 km total shortening perpendicular to the western margin of svalbard is estimated the early stages of the eurekan deformation in north greenland can be linked to that of the west spitsbergen fold belt and the combined shortening across the two fold belts may exceed 80 km in ellesmere island eurekan structures are distributed in an arc like belt which records between 50 to 100 km of shortening since the late cretaceous kinematic reconstructions suggest that before the opening of the eurasian basin and norwegian greenland sea chron 25 svalbard was linked to north america in the late cretaceous palaeocene interval the motion across the greenland svalbard margin was mainly convergent giving rise to the west spitsbergen fold belt and the eurekan structures of north greenland the dextral separation of greenland and svalbard in post chron 24 time was accompanied by extension followed by pure extension in post chron 13 time

a transpressional origin for the west spitsbergen fold and thrust belt insight from analog modeling 1 the west spitsbergen fold and thrust belt formed along the transform plate boundary between greenland and the western barents sea during paleocene eocene breakup in the northern north atlantic approximately 20 40 km margin perpendicular shortening accumulated in the belt has been attributed to transpression and strain partitioning in a restraining bend but also to head on collision we have applied scaled analog tectonic modeling to test the former hypothesis a pack of brittle quartz sand with a shallow thin layer of silicon putty was deformed by transpression at a 15 convergence angle by movement of a basal plate the kinematics was quantified by means of digital particle image velocimetry the result was a doubly vergent transpressional wedge consisting of a steeply tapered retrowedge and a strongly internally deformed steeply tapered prowedge separated by a central strike slip zone and an adjacent low taper thin skinned fold and thrust belt the doubly vergent wedge evolved through several kinematic phases three main stages were identified namely 1 initial distributed deformation 2 development of an oblique doubly vergent wedge with progressive evolution of local strain partitioning along the marginal shear zones and finally 3 a stage of full strain partitioning between a central strike slip zone and reverse displacement along marginal shear zones with folding and thrusting in a thin skinned belt on the proside the analog model convincingly reproduced the geometry and the kinematic evolution of the west spitsbergen fold and thrust belt supporting the hypothesis of its formation by strain partitioning in transpression with a small angle of convergence and significant lateral displacement

state of stress and tectonic evolution of the west spitsbergen fold belt abstract the west spitsbergen fold belt is the result of a e w to ene wsw oriented compression which affected the whole of spitsbergen a late cretaceous palaeocene age for the fold belt deformation is indicated by the involvement of only the basal tertiary conglomerates in the folding and thrusting in western spitsbergen this compressional event was followed by a strike slip stress pattern with nw se oriented extension and ne sw compression which generated micro structures within the tertiary rocks on the map scale normal faults produced by a ne sw oriented extension overprint the compressional structures the later strike slip and extensional stress patterns correspond to the svalbard greenland dextral motion along the de geer zone in latest palaeocene eocene time the latest tectonic event which affected the whole of svalbard was an e w oriented extension related to the spreading along the knipovich ridge in oligocene neogene time

diffusion in irish coastal waters results are presented from dye diffusion experiments performed at a selection of near shore and estuarine sites around the coastline of ireland the data from discrete dye releases have been analysed to derive along and across patch horizontal diffusivities and estimates are presented of both fickian and non fickian diffusion coefficients most of the sites were characterized by strong tidal currents so that the dye became vertically well mixed soon after release consequently the mixing was found to be tidally dominated and to a reasonable approximation the magnitude of the one dimensional radial spreading horizontal diffusivity m 2 s 1 was equal to the tidal current speed m s 1 wind induced mixing was only of secondary importance but this may be a consequence of the experiments having taken place during conditions of generally light winds in general the observed mixing rates agree with those predicted by oceanic diffusion diagrams

remote sensing lower thermosphere wind profiles using non specular meteor echoes 1 this article describes a new method of measuring wind velocity profiles between 93 km and 110 km altitude by tracking non specular meteor echoes as neutral winds transport the plasma trails this requires a large vhf radar with interferometric capability able to point nearly perpendicular to the geomagnetic field a small data sample from the jicamarca radio observatory allows the measurement of horizontal wind speeds and directions with a range resolution of a few hundred meters these observations show speeds reaching 150 m s and sometimes changing by as much as 100 m s over a 6 km altitude range at the best times these measurements can be made with only a few minutes of data with some refinement of the data collection and analysis techniques this technique should produce high resolution images of lower thermospheric winds as they change in both altitude and time