near inertial internal wave field in the canada basin from ice tethered profilers abstractsalinity and temperature profiles from drifting ice tethered profilers in the beaufort gyre region of the canada basin are used to characterize and quantify the regional near inertial internal wave field over one year vertical displacements of potential density surfaces from the surface to 750 m depth are tracked from fall 2006 to fall 2007 because of the time resolution and irregular sampling of the ice tethered profilers near inertial frequency signals are marginally resolved complex demodulation is used to determine variations with a time scale of several days in the amplitude and phase of waves at a specified near inertial frequency characteristics and variability of the wave field over the course of the year are investigated quantitatively and related to changes in surface wind forcing and sea ice cover

statistics of geomagnetic storms and ionospheric storms at low and mid latitudes in two solar cycles 1 the statistics of occurrence of the geomagnetic storms and ionospheric storms at kokubunji 35 7 n 139 5 e 26 8 n magnetic latitude in japan and boulder 40 0 n 254 7 e 47 4 n in america are presented using the dst and peak electron density nmax data in 1985 2005 covering two solar cycles 22 23 when 584 geomagnetic storms dst 50 nt occurred in addition to the known solar cycle and seasonal dependence of the storms the statistics reveal some new aspects 1 the geomagnetic storms show a preference for main phase mp onset at around ut midnight especially for major storms dst 100 nt over 100 excess mp onsets at ut midnight compared to a uniform distribution 2 the number of positive ionospheric storms at kokubunji about 250 is more than double that at boulder and 3 the occurrence of the positive storms at both stations shows a preference for the morning noon onset of the geomagnetic storms as expected from a physical mechanism of the positive storms 4 the occurrence of negative ionospheric storms at both stations follows the solar cycle phases most frequent at solar maximum better than the occurrence of positive storms which agrees with the mechanism of the negative storms

stereo and wind observations of a fast icme flank triggering a prolonged geomagnetic storm on 5 7 april 2010 1 on 5 april 2010 an interplanetary ip shock was detected by the wind spacecraft ahead of earth followed by a fast average speed 650 km s ip coronal mass ejection icme during the subsequent moderate geomagnetic storm minimum dst 72 nt maximum kp 8 communication with the galaxy 15 satellite was lost we link images from stereo secchi to the near earth in situ observations and show that the icme did not decelerate much between sun and earth the icme flank was responsible for a long storm growth phase this type of glancing collision was for the first time directly observed with the stereo heliospheric imagers the magnetic cloud mc inside the icme cannot be modeled with approaches assuming an invariant direction these observations confirm the hypotheses that parts of icmes classified as 1 long duration mcs or 2 magnetic cloud like mcl structures can be a consequence of a spacecraft trajectory through the icme flank

global ionospheric and thermospheric response to the 5 april 2010 geomagnetic storm an integrated data model investigation we present a case study of the 5 april 2010 geomagnetic storm using observations and numerical simulations the event was driven by a fast moving coronal mass ejection and despite being a moderate storm with a minimum dst near 50 nt the event exhibited elevated thermospheric density and surges of traveling atmospheric disturbances tads more typically seen during major storms the thermosphere ionosphere mesosphere electrodynamics general circulation model timegcm was used to assess how these features were generated and developed during the storm the model simulations gave rise to tads that were highly nonuniform with strong latitude and longitude local time dependence the tad phase speeds ranged from 640 m s to 780 m s at 400 km and were 5 lower at 300 km and approximately 10 15 lower at 200 km in the lower thermosphere around 100 km the tad signatures were nearly unrecognizable due to much stronger influence of upward propagating atmospheric tides the thermosphere simulation results were compared to observations available from the gravity field and steady state ocean circulation explorer goce challenging minisatellite payload champ and gravity recovery and climate experiment grace satellites comparison with goce data shows that the timegcm reproduced the cross track winds over the polar region very well the model data comparison also revealed some differences specifically the simulations underestimated neutral mass density in the upper thermosphere above 300 km and overestimated the storm recovery tome by 6 h these discrepancies indicate that some heating or circulation dynamics and potentially cooling processes are not fully represented in the simulations and also that updates to some parameterization schemes in the timegcm are warranted

a new high resolution unstructured grid finite volume arctic ocean model ao fvcom an application for tidal studies 1 a spherical coordinate version of the unstructured grid 3 d fvcom finite volume coastal ocean model has been applied to the arctic ocean to simulate tides with a horizontal resolution ranging from 1 km in the near coastal areas to 15 km in the deep ocean by accurately resolving the irregular coastlines and bathymetry in the arctic ocean coastal regions this model reproduces the diurnal k1 and o1 and semidiurnal m2 and s2 tidal wave dynamics and captures the complex tidal structure along the coast particularly in the narrow straits of the canadian archipelago the simulated tidal parameters harmonic constituents of sea surface elevation and currents agree well with the available observational data high resolution meshes over the continental shelf and slope capture the detailed spatial structure of topographic trapped shelf waves which are quite energetic along the greenland siberia and spitsbergen continental slope and shelf break areas water stratification influences the vertical distribution of tidal currents but not the water transport and thus tidal elevation the comparison with previous finite difference models suggests that horizontal resolution and geometric fitting are two prerequisites to simulate realistically the tidal energy flux in the arctic ocean particularly in the canadian archipelago

geochemistry of caledonian metabasalts from some norwegian ophiolite fragments major and trace element analyses of metabasalts from five of the lower palaeozoic caledonian ophiolite fragments along a strike distance of some 800 km of the west norwegian coast are presented characteristically the ree patterns show depletion of both lree and hree relative to intermediate ree giving an upward convex shape but nearly flat lree depleted or enriched patterns occur the ree patterns of the metabasalts from three of these sequences i e the lykling solund and stavfjorden ophiolite fragments show little within sequence but large between sequence variation the ree patterns of the metabasalts from the gullfjellet major bergen arc and skalvaer ophiolite fragments however show significant within sequence variations indicative of local source heterogeneties

a case study of observed and modeled barrier flow in the denmark strait in may 2015 abstractmesoscale barrier jets in the denmark strait are common in winter months and have the capability to influence open ocean convection this paper presents the first detailed observational study of a summertime 21 may 2015 barrier wind event in the denmark strait using dropsondes and observations from an airborne doppler wind lidar dwl the dwl profiles agree well with dropsonde observations and show a vertically narrow 250 400 m barrier jet of 23 28 m s 1 near the greenland coast that broadens 300 1000 m and strengthens farther off coast in addition otherwise identical regional high resolution weather research and forecasting wrf model simulations of the event are analyzed at four horizontal grid spacings 5 10 25 and 50 km two vertical resolutions 40 and 60 levels and two planetary boundary layer pbl parameterizations mellor yamada nakanishi niino version 2 5 mynn2 5 and university of washington uw to determine what model configurations best simulate the observed jet

on the spatial and temporal distribution of near inertial energy in the southern ocean 1 we use an eddying realistic primitive equation model of the southern ocean to examine the spatial and temporal distribution of near inertial wind power input wpi and near inertial energy nie in the southern ocean we find that the modeled near inertial wpi is almost proportional to inertial wind stress variance iwsv while the modeled nie is modulated by the inverse of the mixed layer depth we go on to assess recent decadal trends of near inertial wpi from trends of iwsv based on reanalysis wind stress averaged over the southern ocean annual mean iwsv is found to have increased by 16 over the years 1979 2011 part of the increase of iwsv is found to be related to the positive trend of the southern annular mode over the same period finally we show that there are horizontal local maxima of nie at depth that are almost exclusively associated with anticyclonic eddies

remapping the thickness distribution in sea ice models in sea ice models with multiple thickness categories the ice thickness distribution evolves in time the evolution of the thickness distribution as ice grows and melts is analogous to one dimensional fluid transport and can be treated by similar numerical methods one such method remapping is applied here thickness categories are represented as lagrangian grid cells whose boundaries are projected forward in time the thickness distribution is approximated as a linear or quadratic polynomial in each displaced category and ice area and volume are transferred between categories so as to restore the original boundaries in simple test problems and in a single column model with forcing typical of the central arctic remapping performs significantly better than methods previously used in sea ice models it is less diffusive than a scheme that fixes the ice thickness in each category and behaves better numerically than a scheme that represents the thickness distribution as a set of delta functions also remapping converges faster i e with fewer thickness categories than the alternative schemes with five to seven categories the errors due to finite resolution of the thickness distribution are much smaller than the errors due to other sources linear remapping performs as well as the more complex quadratic version and is recommended for climate modeling its computational cost is minimal compared to other sea ice model components

observation of cyclone induced inertial sea ice oscillation in fram strait 1 in march 2007 the field campaign framzy took place in the region between spitsbergen and greenland one goal of the experiment was the observation of cyclone impact on ice drift by means of autonomous meteorological buoys deployed on sea ice on 23 march an intense cyclone of about 500 km diameter passed with about 20 m s from south to north over the ice covered part of the fram strait and induced strong inertial oscillations of the sea ice ice drift velocity fluctuations abruptly increased by a factor of three to values of more than 1 m s this was caused by a resonant wind forcing for almost three quarters of the inertial oscillation depending on the local ice conditions the oscillations lasted over a two to five days period the inertial oscillations caused ice drift divergence fluctuations of 6 10 6s 1 and a reduction of ice concentration by up to 11

winter atmospheric buoyancy forcing and oceanic response during strong wind events around southeastern greenland in the regional arctic system model rasm for 1990 2010 abstractstrong mesoscale tip jets and barrier winds that occur along the southeastern greenland coast have the potential to impact deep convection in the irminger sea the self organizing map som training algorithm was used to identify 12 wind patterns that represent the range of winter november march ndjfm wind regimes identified in the fully coupled regional arctic system model rasm during 1990 2010 for all wind patterns the ocean loses buoyancy primarily through the turbulent sensible and latent heat fluxes haline contributions to buoyancy change were found to be insignificant compared to the thermal contributions patterns with westerly winds at the cape farewell area had the largest buoyancy loss over the irminger and labrador seas due to large turbulent fluxes from strong winds and the advection of anomalously cold dry air over the warmer ocean similar to observations rasm simulated typical ocean mixed layer depths mld of approximately 400 m throughout the irminger basin with indi

the influence of high frequency atmospheric forcing on the circulation and deep convection of the labrador sea abstractthe influence of high frequency atmospheric forcing on the circulation of the north atlantic ocean with emphasis on the deep convection of the labrador sea was investigated by comparing simulations of a coupled ocean ice model with hourly atmospheric data to simulations in which the high frequency phenomena were filtered from the air temperature and wind fields in the absence of high frequency atmospheric forcing the strength of the atlantic meridional overturning circulation and subpolar gyres was found to decrease by 25 in the labrador sea the eddy kinetic energy decreased by 75 and the average maximum mixed layer depth decreased by between 20 and 110 depending on the climatology in particular high frequency forcing was found to have a greater impact on mixed layer deepening in moderate to warm years whereas in relatively cold years the temperatures alone were enough to facilitate deep convection additional simulations in which either the wind or temperature was filtered revealed that

the annieopsquotch ophiolite belt of southwest newfoundland geology and tectonic significance the annieopsquotch ophiolite belt consists of ophiolite fragments exposed from buchans in central newfoundland to the southwest tip of the island the largest remnants belong to the annieopsquotch complex in the northeast and the long range mafic ultramafic complex in the southwest the arenigian annieopsquotch complex exposes an ophiolite stratigraphy from layered cumulate gabbro moho sequence through high level gabbro sheeted dikes pillow lava and chert the long range mafic ultramafic complex consists largely of cumulate and high level metagabbro with subordinate ultramafic rock and metabasalt all engulfed as massif to xenolith size fragments in ordovician tonalitic and younger mafic to felsic granitoid intrusions the latter rocks are intersected by a wide locally gently inclined high temperature ductile thrust zone which also encompasses amphibolite semipelitic schist and marble between buchans and the southwest tip of newfoundland the tonalite terrane encloses many smaller ophiolitic fragments the ophiolite fragments of the northern half of the belt have similar dike trends have n type morb chemistry and likely formed one major allochthon of iapetus oceanic crust this was disrupted by the intrusion of tonalite and other magmas in an arc or arc trench environment and by subsequent faulting an attempt is made to assess the significance of the annieopsquotch belt in relation to ether newfoundland ophiolites

simulating the ice thickness distribution in a coupled climate model climate simulations in a global coupled model are investigated using a dynamic thermodynamic sea ice and snow model with sophisticated thermodynamics and a subgrid scale parameterization for multiple ice thicknesses in addition to the sea ice component the model includes a full primitive equation ocean and a simple energy moisture balance atmosphere we introduce a formulation of the ice thickness distribution that is lagrangian in thickness space the method is designed to use fewer thickness categories because it adjusts to place resolution where it is needed most and it is free of diffusive effects that tend to smooth eulerian distributions experiments demonstrate that the model does reasonably well in simulating the mean arctic climate we find the climate of the arctic and northern north atlantic is sensitive to resolving the ice thickness distribution when comparing the model results to a simulation with a two level sea ice model the ice thickness distribution causes ice export through fram strait to be more variable and more strongly linked to meridional overturning in the north atlantic ocean the lagrangian formulation of the ice thickness distribution allows for the inclusion of a vertical temperature profile with relative ease compared to an eulerian method we find ice growth rates and ocean surface salinity differ in our model with a well resolved vertical temperature profile in the ice and snow and an explicit brine pocket parameterization compared to a simulation with semtner zero layer thermodynamics although these differences are important for the climate of the arctic the effects of an ice thickness distribution are more dramatic and extend into the northern north atlantic sensitivity experiments indicate that five ice thickness categories with 50 cm vertical temperature resolution capture the effects of the ice thickness distribution on the heat and freshwater exchange across the surface in the presence of sea ice in these simulations

near inertial internal waves and sea ice in the beaufort sea the evolution of the near inertial internal wavefield from ice free summertime conditions to ice covered wintertime conditions is examined using data from a yearlong deployment of six moorings on the beaufort continental slope from august 2008 to august 2009 when ice is absent from july to october energy is efficiently transferred from the atmosphere to the ocean generating near inertial internal waves when ice is present from november to june storms also cause near inertial oscillations in the ice and mixed layer but kinetic energy is weaker and oscillations are quickly damped damping is dependent on ice pack strength and morphology decay scales are longer in early winter november january when the new ice pack is weaker and more mobile decreasing in late winter february june when the ice pack is stronger and more rigid efficiency is also reduced as comparisons of atmospheric energy available for internal wave generation to mixed layer kinetic energies indicate that a smaller percentage of atmospheric energy is transferred to nearinertial motions when ice concentrations are 90 however large kinetic energies and shears are observed during an event on 16 december and spectral energy is elevated above garrett munk levels coinciding with the largest energy flux predicted during the deployment a significant amount of near inertial energy is episodically transferred to the internal wave band from the atmosphere even when the ocean is ice covered however damping by ice and less efficient energy transfer still leads to low arctic internal wave energy in the near inertial band increased kinetic energy below 300m when ice is forming suggests some events may generate internal waves that radiate into the arctic ocean interior

role of strike slip faulting in the evolution of allochthonous terranes in the philippines concepts of allochthonous terrane transport and emplacement are dominated by the assumption that most terranes originate on the subducting plate collide with the upper plate and are emplaced there movement of terranes along the convergent margin is recognized but is generally attributed to postcollision slip in the northern philippines allochthonous terranes originate primarily within the arc system have been translated along it by strike slip faults and were emplaced by cessation of that slip the authors suggest that in the philippines some originally vertical strike slip boundaries may have evolved into shallow dipping sutures marked by fold and thrust systems this mode of terrane evolution may be more common than generally appreciated particularly in orogenic belts developed in response to oblique convergence

revisiting internal waves and mixing in the arctic ocean 1 to determine whether deep background mixing has increased with the diminishment of the arctic sea ice we compare recent internal wave energy and mixing observations with historical measurements since 2007 the north pole environmental observatory has launched expendable current probes xcps as a part of annual airborne hydrographic surveys in the central arctic ocean mixing in the upper 500 m is estimated from xcp shear variance and conductivity temperature depth ctd derived brunt vaisala frequency internal wave energy levels vary by an order of magnitude between surveys although all surveys are less energetic and show more vertical modes than typical midlatitude garrett munk gm model spectra survey averaged mixing estimates also vary by an order of magnitude among recent surveys comparisons between modern and historical data reanalyzed in identical fashion reveal no trend evident over the 30 year period in spite of drastic diminution of the sea ice turbulent heat fluxes are consistent with recent double diffusive estimates both mixing and internal wave energy in the beaufort sea are lower when compared to both the central and eastern arctic ocean and expanding the analysis to mooring data from the beaufort sea reveals little change in that area compared to historical results from arctic internal wave experiment we hypothesize that internal wave energy remains lowest in the beaufort sea in spite of dramatic declines in sea ice there because increased stratification amplifies the negative effect of boundary layer dissipation on internal wave energy

springtime ice motion in the western antarctic peninsula region abstract oscillatory motion of sea ice is examined using two ice drifting buoys separated by 1 latitude near 66 s during the winter to spring transition in the marguerite bay region west of the antarctic peninsula the buoys motions exhibit spectrally distinct periods 12 87 0 04 and 13 03 0 04 h respectively despite highly correlated motion between them r2 is 0 62 and 0 81 for u and v respectively the periods shift with latitude and nearly match the local inertial periods 13 00 and 13 10 h respectively the oscillations are further examined with respect to the kinematics involved in the breakup process of sea ice these include hourly resolved manifestations of circular trajectories semi circular oscillations with compressed trajectory cusps and accordion like compressions along straight line trajectories oscillations are found in all trajectory types over the lifetime of both buoys several months traditional circular and semi circular oscillations are particularly prominent during two episodes one of which is preceded by strong wind events and a substantial decrease in ice thickness and concentration these episodes combine with seasonally warming temperatures to break up and melt the sea ice cover we discuss potential relationships between the degradation of the ice pack during spring breakup and the increase in energy at near inertial frequencies including the appearance of a non linear cascade of energy within the ice from the low frequencies commensurate with storms and fortnightly tides to semi diurnal frequencies we further comment on the implications this type of high frequency motion has on local biological ecosystems specifically we find that sea ice semi diurnal oscillations are at their peak during the final decay of sea ice just before springtime primary productivity begins hence the oscillatory motion of sea ice not only serves as an effective mixing agent within the ice ocean mixed layer but also serves as an effective seeding platform for distributing phyto and zooplankton overwintering within and around the ice floes

complete remagnetization of some permian dykes from western norway induced during burial uplift abstract stable paleomagnetic directions in four basaltic dykes and in some associated caledonian metamorphic rocks define high latitude mesozoic paleomagnetic pole positions which are not compatible with the k ar age of 250 my determined for the dykes a monotonic increase of 40 occurs in the potassium content of samples taken across a dyke 32 cm wide this is accompanied by only a 1 2 variation in the k ar age of the samples suggesting the absence of any significant level of initial argon titanomagnetite grains having bulk compositions around x 0 6 have suffered extensive low temperature alteration forming assemblages of ferri rutile granules in a matrix of pure magnetite the complete remagnetisation of both the dykes and the associated country rocks is probably an expression of a vrm acquired at elevated temperatures 150 500 c at the emplacement depth of the dykes a stable remanent magnetisation was locked in during uplift of the area probably related to the kimmerian basin development in the adjacent north sea and the epeirogenic uplift of western fennoscandia

direct observations of the role of convection electric field in the formation of a polar tongue of ionization from storm enhanced density 1 we examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization toi from midlatitude plumes of storm enhanced density sed observations from the geomagnetic storm on 26 27 september 2011 are presented for two distinct sed events during an hour long period of geomagnetic activity driven by a coronal mass ejection a channel of high density f region plasma was transported from the dayside subauroral ionosphere and into the polar cap by enhanced convection electric fields extending to middle latitudes this toi feature was associated with enhanced hf backscatter indicating that it was the seat of active formation of small scale irregularities after the solar wind interplanetary magnetic field conditions quieted and the dayside convection electric fields retreated to higher latitudes an sed plume was observed extending to but not entering the dayside cusp region this prominent feature in the distribution of total electron content tec persisted for several hours and elongated in magnetic local time with the rotation of the earth no ionospheric scatter from superdarn radars was observed within this sed region the source mechanism enhanced electric fields previously drawing the plasma from midlatitudes and into the polar cap as a toi was no longer active resulting in a fossil feature we thus demonstrate the controlling role exercised by the convection electric field in generating a toi from midlatitude sed

geochronology of the buchans roberts arm and victoria lake groups and mansfield cove complex newfoundland volcanic groups of the central mobile belt of the newfoundland appalachians have previously been subdivided into early and late arc sequences separated in time by a quiescent caradocian stage defined in some areas by fossil bearing black shales new u pb zircon ages of and 473 2 ma for rhyolites of the buchans and roberts arm groups respectively show them to be correlative early ordovician sequences these ages serve to refute both the previous rb sr whole rock isochron ages of 447 ma and the idea that these groups were late arc sequences these new ages corroborate evidence from late arenig early llanvirn conodonts in the buchans group and calibrate this fossil occurrence a new u pb zircon age of 479 3 ma from plagiogranite of the mansfield cove complex immediately west of the roberts arm group shows that this plutonic body is only slightly older than the adjacent volcanic rocks and not hadrynian as previously supposed local field relationships suggest this body may represent part of a dis

u pb ages of ophiolites and arc related plutons of the norwegian caledonides implications for the development of iapetus u pb zircon ages are reported for four ophiolites and three crosscutting arc related plutons from the norwegian caledonides plagiogranite differentiated from gabbro of the karmoy ophiolite is dated at 493 7 4 ma whereas arc related trondhjemite cutting this ophiolite crystallized at 485 2 ma a crosscutting clinopyroxene phyric gabbro intrusion is dated at 470 9 5 ma by near concordant magmatic titanite sphene and discordant u rich 2903 6677 ppm zircon lower intercepts of 247 68 and 191 70 ma defined by the plagiogranite and clinopyroxene phyric gabbro best fit lines may reflect a real low t alteration rift related event

observations of tidally induced currents over the continental slope of the laptev sea arctic ocean abstracttwo year long 2004 05 and 2005 06 records of currents from two moorings deployed at the continental slope of the laptev sea 78 26 n 125 40 e are used in order to define the properties of tidal currents in the upper 200 m ocean layer harmonic and spectral analyses of currents showed that the semidiurnal tidal constituent s2 dominates over the semidiurnal m2 and diurnal constituents this dominance of the s2 constituent in the tidal currents is due to resonant interaction of the superinertial wave with sloping bottom topography in contrast to the tidal currents sea level changes are dominated by the m2 constituent as seen from a tidal model by l padman and s erofeeva using assimilation of observational data strong anticorrelation 0 73 0 05 was found between the upper 50 m s2 current amplitudes and local sea ice concentration with fourfold from 2 0 to 8 5 cm s 1 amplification of tidal currents under ice free conditions this is probably due to a change of local resonance condit

the origin of oceanic plagiogranites from the karmoy ophiolite western norway both field relationships and geochemical characteristics indicate two suites of plagiogranitic and related rocks coexisting in the higher parts of the karmoy ophiolite of western norway the plutonic zone of this ophiolite can be subdivided into three complexes the east karmoy igneous complex the visnes high level complex and the veavagen igneous complex and plagiogranitic rocks are well developed in the first two of these within the east karmoy igneous complex plagiogranites are associated with high temperature pre basic dyke shear zones rare earth element modelling indicates that these plagiogranites were derived by anatexis of amphibolite hydrated diabase assuming a starting material consisting of 40 hornblende and 60 plagioclase and that batch melting occurred within the stability field of hornblende in comparison plagiogranite occurs in a number of bodies in the upper part of the visnes high level complex and forms a sandwich horizon together with biotite diorites and epidosites between a roof assemblage of dykes microgabbros and magnetite gabbros and a floor assemblage of layered and non layered gabbros the r e e modelling of the petrogenesis of this series of plagiogranites indicates that they were derived by filter pressing of a differentiated interstitial liquid to the vari textured gabbros although the distribution of highly hygromagmatophile elements such as k rb ba etc cannot be explained satisfactorily by this model alone depletion in these elements appears to be an autometasomatic effect

modeling the high frequency component of arctic sea ice drift and deformation abstract buoy observations of sea ice drift show that sea ice motion and deformation contain substantial high frequency variability at subdaily timescales however numerical simulations of the sea ice dynamics normally do not include processes on such short timescales instead by applying traditional water drag formulations for the ocean sea ice boundary layer the inertial frequencies tend to be omitted in the spectra of modeled sea ice motion and deformation due to fictitious ocean damping here a dynamic thermodynamic sea ice model is presented that includes inertial embedding of the sea ice into the oceanic boundary layer to reproduce sea ice motion and deformation not only at daily and lower frequencies but also at subdaily frequencies up to 2 cycles per day and higher comparison with buoy data shows that the embedded model much more successfully simulates the observed sea ice motion in regard to the high frequency component the results demonstrate that both inertial embedding of the sea ice oc

shear deformation and eclogite formation within granulite facies anorthosites of the bergen arcs western norway the anorthosites of the bergen arcs contain two distinct metamorphic mineral assemblages which are stable under different p t conditions a granulite facies assemblage which equilibrated at t 800 900 c p 10 kbar is defined by the minerals plagioclase al rich diopside cpx i garnet gnt i scapolite orthopyroxene dark brown hornblende this assemblage is linked by corona structures to a primary magmatic mineralogy where coexistence of olivine and plagioclase limits the maximum crystallization pressure of the anorthosites to 8 kbar at 1200 c the anorthosites are transected by a series of fine grained shear zones in which the granulite facies assemblage is replaced by an eclogite mineralogy defined by omphacite cpx ii jd40 50 garnet kyanite epidote clinozoisite phengite quartz amphibole with plagioclase sometimes remaining in the marginal parts mineral compositions indicate equilibration conditions for the eclogite paragenesis of t 700 800 c p 16 19 kbar a series of textural and mineralogical changes which can be observed as the strain increases into the shear zones demonstrates that the eclogite mineralogy is formed at the expense of the granulite facies minerals during the early stages of shear zone development the eclogite mineralogy defines a strong mylonitic fabric which again is truncated by centimetres thick secondary shear zones containing clasts of both granulite and eclogite minerals these latter fine grained ultramylonites may be connected to uplift of this deep seated complex the eclogite shear zones are highly oblique to the granulite structures indicating that the eclogite shear zones formed under a new stress regime rb sr dating shows that the granulite facies assemblage formed in sveconorwegian time or earlier while minerals from shear zones define ages around 400 ma indicating a caledonian formation of the eclogites this work demonstrates the critical role of deformation in triggering metamorphic reactions whether the shear stress also was important in stabilizing the eclogite assemblages is not clear from the available data

modeling sea ice transport using incremental remapping sea ice models contain transport equations for the area volume and energy of ice and snow in various thickness categories these equations typically are solved with first order accurate upwind schemes which are very diffusive with second order accurate centered schemes which are highly oscillatory or with more sophisticated second order schemes that are computationally costly if many quantities must be transported e g multidimensional positive definite advection transport algorithm mpdata here an incremental remapping scheme originally designed for horizontal transport in ocean models is adapted for sea ice transport this scheme has several desirable features it preserves the monotonicity of both conserved quantities and tracers it is second order accurate except where the accuracy is reduced locally to preserve monotonicity and it efficiently solves the large number of equations in sea ice models with multiple thickness categories and tracers remapping outperforms the first order upwind scheme and basic mpdata scheme in several simple test problems in realistic model runs remapping is less diffusive than the upwind scheme and about twice as fast as mpdata

a physical mechanism of positive ionospheric storms at low latitudes and midlatitudes 1 a physical mechanism of the positive ionospheric storms at low latitudes and midlatitudes is presented through multi instrument observations theoretical modeling and basic principles according to the mechanism an equatorward neutral wind is required to produce positive ionospheric storms the mechanical effects of the wind 1 reduce or stop the downward diffusion of plasma along the geomagnetic field lines 2 raise the ionosphere to high altitudes of reduced chemical loss and hence 3 accumulate the plasma at altitudes near and above the ionospheric peak centered at around 30 magnetic latitudes daytime eastward prompt penetration electric field ppef if it occurs also shifts the equatorial ionization anomaly crests to higher than normal latitudes up to approximately 30 latitudes the positive ionospheric storms are most likely in the longitudes where the onset of the geomagnetic storms falls in the ionization production dominated morning noon local time sector when the plasma accumulation due to the mechanical effects of the wind largely exceeds the plasma loss due to the chemical effect of the wind the mechanism agrees with the multi instrument observations made during the supergeomagnetic storm of 7 8 november 2004 with 18 h long initial phase ip and 10 h long main phase mp the observations which are mainly in the japanese australian longitudes where the mp onset was in the morning 0600 lt 2100 ut show 1 strong positive ionospheric storms in ne nmax hmax global positioning system total electron content gps tec and 630 nm airglow intensity in both northern and southern hemispheres started at the morning 0600 lt mp onset and lasted for a day 2 repeated occurrence of strong eastward ppef events penetrated after the mp onset and superposed with westward electric field started before the mp onset and 3 storm time equatorward neutral winds inferred from 1 and 2 repeated occurrence of an unusually strong f3 layer with large density depletions around the equator was also observed during the morning noon mp

global distribution of the decay timescale of mixed layer inertial motions observed by satellite tracked drifters 1 the decay timescale of mixed layer inertial amplitudes has been estimated from satellite tracked drifter trajectories from 1990 to 2004 as the e folding timescale of the temporal correlation functions the decay timescales increase with latitude in all basins except the north atlantic a beta dispersion model shows that dephasing leads to meridional variations of the decay timescale in the north pacific and the southern ocean but meridional variations of the buoyancy structure in the north atlantic act to compensate the beta effect leading to a lack of meridional variation of the decay timescale in that ocean

coastal transition zone off chile 1 seven years of subsurface current observations at deep sea and continental slope moorings off chile 30 s satellite sea surface anomaly and satellite wind stress are used to examine space time and propagation characteristics of the mesoscale eddy activity in the coastal transition zone off chile this zone off chile extends from the coast to 600 800 km offshore and can be separated into two latitudinal regions the first region between 29 and 39 s off central chile is characterized by high eddy kinetic energy and strong but variable equatorward wind stress the second region between 19 and 29 s off northern chile is characterized by low eddy kinetic energy and weak but persistent equatorward wind stress low frequency mesoscale variability off central chile is mainly associated with baroclinic instability of coastal currents and westward propagation of rossby waves from the eastern boundary and is strongly modulated over el nino la nina cycles application of a new rotary wavelet spectrum method to the recording current meter data and the use of current estimates from satellite altimeter data show that mesoscale eddies and meanders in the coastal transition zone fluctuate with periods centered on 120 days and with length scales centered on 200 km cross rotary wavelet analyses of currents and wind stress indicate that fluctuations of coastal currents with periods longer than 220 days propagated westward as free rossby waves during 1995 1996 and as forced rossby waves during 1999 2001

global statistics of inertial motions statistics of inertial currents in the north pacific north atlantic and southern ocean are derived for the period 1997 2003 from surface trajectories of argo profiling floats by employing a method developed recently by park et al 2004 the distribution of inertial amplitudes is non gaussian in the range 0 80 cm sec with an average value of 13 7 cm sec the inertial amplitude in the mid latitude 30 45 n band exceeds those in both the low 15 30 n and high 45 60 n latitude bands in three basins the amplitude in summer is greater than that in winter by 15 25 the inertial energy in the mixed layer reaches approximately 1100 j m2 1165 j m2 globally the spatiotemporal patterns of inertial amplitudes in the north atlantic mostly depend on the mld which exhibits strong meridional gradients however the small meridional gradient of the mld in the north pacific does not contribute significantly to the spatial distribution of inertial amplitudes the total inertial energy estimated from the floats is consistent with the theory that inertial energy could contribute significantly to sustaining the meridional overturning circulation

ionospheric redistribution during geomagnetic storms 1 the abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms recent reports suggest that the magnitude of the plasma density enhancement depends on the ut of storm onset this possibility is investigated over a 7year period using global maps of ionospheric total electron content tec produced at the jet propulsion laboratory the analysis confirms that the american sector exhibits on average larger storm time enhancement in ionospheric plasma content up to 50 in the afternoon middle latitude region and 30 in the vicinity of the high latitude auroral cusp with largest effect in the southern hemisphere we investigate whether this effect is related to the magnitude of the causative magnetic storms using the same advanced dst index employed to sort the tec maps into quiet and active dst 100 nt sets we find variation in storm strength that corresponds closely to the tec variation but follows it by 3 6h for this and other reasons detailed in this report we conclude that the ut dependent peak in storm time tec is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the south american region the large dst variation suggests a possible system level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current possibly connected through ut dependent modulation of ion outflow

ordovician volcanism in the welsh borderland basaltic andesitic and rhyodacitic rhyolitic volcanism was widespread during ordovician time in the welsh basin new chemical data are presented for llanvirn to caradoc lavas and tuffs from the welsh borderland which during ordovician time formed the southeastern margin of the welsh basin in view of the observed chemical alteration immobile elements are used in the interpretation of the original geochemical character the data indicate that the llanvirn stapeley volcanic group of the shelve inlier was a bimodal basalt basaltic andesite rhyodacite rhyolite association the basalts have trace element contents of tholeiitic associations with a subduction related character the caradoc whittery and hagley volcanic groups of the shelve inlier comprise lavas and tuffs of calc alkaline andesite blocks sampled from the breidden hills show that these were also derived from a calc alkaline volcano associated caradoc pumice and ash flow deposits from the breidden hills are probably of altered calc alkaline rhyodacite rhyolite composition the sibdon carwood basalt flow the only known example of ordovician volcanism east of the pontesford linley and church stretton lineaments has transitional tholeiitic to alkaline character with trace element contents influenced by subduction related processes the overall tholeiitic to calc alkaline nature of the magmatism is consistent with the view that during llanvirn to caradoc time the welsh basin was an ensialic marginal basin

uranium lead zircon and titanite ages from the northern portion of the western gneiss region south central norway abstract the geochronologic history of the northern portion of the western gneiss region south central norway has been investigated by u pb analyses of zircon and titanite from various basement units and one supracrustal gneiss a six point four zircon and two titanite discordia line from a migmatite melt pod and its host gneiss astfjord migmatite gneiss defines upper and lower intercept ages of 1659 1 1 8 ma and 393 6 3 6 ma respectively the upper intercept age is interpreted as a time of tonalite emplacement and migmatite formation in the region a seven point three zircon and four titanite discordia line from the ingdal granite gneiss has similar upper and lower intercept ages 1652 9 1 7 ma and 396 1 4 9 ma respectively and the upper intercept age is interpreted as the time of granite crystallization the lower intercept age from both theastfjord migmatite gneiss and the ingdal granite gneiss is interpreted as the time of regional metamorphic resetting and is evidence for caledonian influence in the region titanite from these two gneiss units as well as from other tonalite granite and supracrustal gneisses throughout the western gneiss region displays a remarkably uniform pattern of discordance titanite discordance is variable from 6 to 100 and in general the degree of discordance is proportional to the caledonian metamorphic grade of nearby supracrustal schists episodic diffusional lead loss from titanite during caledonian metamorphism probably caused the discordance pattern but a combined mechanism of mixing and diffusional lead loss cannot be ruled out in any case the seventeen point titanite and zircon discordia line clearly indicates that 1 the bulk of the granitoid terrane in this portion of the western gneiss region was emplaced migmatized and cooled in a short time interval about 1657 ma ago 2 a second short lived thermal event that exceeded the blocking temperature of titanite occurred about 395 ma ago and 3 titanite and zircon in the region were not isotopically disturbed by comparable geologic events in the period from 1657 to 395 ma or at any time after 395 ma

effects of magnetic clouds on the occurrence of geomagnetic storms the first 4 years of wind 1 we investigate geomagnetic activity associated with magnetic clouds as well as some aspects of the clouds magnetic field structure e g magnetic field distributions of the clouds thirty four magnetic cloud events observed by wind over the years 1995 1998 are investigated in this study magnetic clouds are a principal source of strong long lasting interplanetary negative bz fields in solar magnetospheric coordinates and hence are a major source of geomagnetic activity dst 50 nt the region just upstream of a cloud may be a significant source of southward fields instead of or as well as the cloud itself we call this upstream region a sheath if it is bounded by a shock or a pressure pulse and the cloud this study helps to identify the major sources regions of southward bz following shock passages or within the magnetic clouds that are most dominant in the generation of geomagnetic storms it is found that a geomagnetic storm can be induced by 1 a sheath 2 the leading i e front part region of a cloud 3 the trailing part of a cloud and 4 both sheath and cloud regions because of this complexity a storm with a multistep main phase can occur the related occurrence percentages of storms were 17 6 six events 44 1 15 events 5 9 two events and 20 6 seven events and the averaged storm intensities minimum dst were 60 85 92 and 58 nt respectively for the remaining four events 11 8 there were no storms the occurrence timing of storm intensity is highly correlated with the occurrence timing of minimum bz maximum vbs or for a magnetic cloud with the field rotating from southward to northward

modeling m2 tidal variability in arctic sea ice drift and deformation semi diurnal oscillations are a ubiquitous feature of polar sea ice motion over much of the arctic basin inertial and semi diurnal tidal variability have similar frequencies so that periodicity alone is inadequate to determine the source of oscillations we investigate the relative roles of tidal and inertial variability in arctic sea ice using a barotropic ice ocean model with sea ice embedded in an upper boundary layer results from this model are compared with levitated ice ocean coupling used in many models in levitated models the mechanical buoyancy effect of sea ice is neglected so that convergence of ice for example does not affect the oceanic ekman flux we use rotary spectral analysis to compare simulated and observed results this helps to interpret the rotation sense of sea ice drift and deformation at the semi diurnal period and is a useful discriminator between tidal and inertial effects results indicate that the levitated model generates an artificial inertial resonance in the presence of tidal and wind forcing contrary to the embedded sea ice model we conclude that sea ice mechanics can cause the rotational response of ice motion to change sign even in the presence of strong and opposing local tidal forcing when a physically consistent dynamic ice ocean coupling is employed

u pb geochronology of the coney head complex newfoundland the coney head complex white bay newfoundland comprises allochthonous plutonic rocks and deformed equivalents emplaced over the continental margin during the ordovician taconic orogeny a u pb zircon age of 474 2 ma for tonalite considered as having formed by partial melting in an island arc indicates that it crystallized in arenig time a microgranite dated by u pb zircon titanite at 432 2 ma cuts the tonalite inherited proterozoic zircon in the microgranite indicates that the rock formed from magma generated in part by melting of continental crust or sediments derived from such crust these relationships indicate that the microgranite was emplaced in silurian time after ordovician transport of the tonalite above a continental substrate

simulating transient ice ocean ekman transport in the regional arctic system model and community earth system model this work evaluates the fidelity of the polar marine ekman layer in the regional arctic system model rasm and community earth system model cesm using sea ice inertial oscillations as a proxy for ice ocean ekman transport a case study is presented that demonstrates that rasm replicates inertial oscillations in close agreement with motion derived using the gps this result is obtained from a year long case study pre dating the recent decline in perennial arctic sea ice using rasm with sub hourly coupling between the atmosphere sea ice and ocean components to place this work in context the rasm coupling method is applied to cesm increasing the frequency of oceanic flux exchange from once per day in the standard cesm configuration to every 30 min for a single year simulation this change causes a considerable increase in the median inertial ice speed across large areas of the southern ocean and parts of the arctic sea ice zone the result suggests that processes associated with the passage of storms over sea ice e g oceanic mixing sea ice deformation and surface energy exchange are underestimated in earth system models that do not resolve inertial frequencies in their marine coupling cycle