mineralogical characterization of some basaltic asteroids in the neighborhood of 4 vesta first results abstract we present reflectance spectra of 19 v type asteroids obtained at the 3 6 m telescopio nazionale galileo covering 0 8 to 2 5 m for 8 of these asteroids we obtained also visible spectra in the same observational run the range from 0 8 to 2 5 m encompassing the 1 and 2 m pyroxene features allows a precise mineralogical characterization of these asteroids the obtained data suggests the possible coexistence of distinct mineralogical groups among the v type asteroids either probing different layers of 4 vesta or coming from different bodies no clear correlation was found between mineralogies and the objects being or not member of the vesta dynamical family

reconstructability of three dimensional upper ocean circulation from swot sea surface height measurements abstractutilizing the framework of effective surface quasigeostrophic esqg theory this study explores the potential of reconstructing the 3d upper ocean circulation structures including the balanced vertical velocity w field from high resolution sea surface height ssh data of the planned surface water and ocean topography swot satellite mission specifically the authors utilize the 1 30 submesoscale resolving ofes model output and subject it to the swot simulator that generates the along swath ssh data with expected measurement errors focusing on the kuroshio extension region in the north pacific where regional rossby numbers range from 0 22 to 0 32 this study finds that the esqg dynamics constitute an effective framework for reconstructing the 3d upper ocean circulation field using the modeled ssh data as input the esqg reconstructed relative vorticity and w fields are found to reach a correlation of 0 7 0 9 and 0 6 0 7 respectively in the 1000 m upper ocean when compared to the orig

a direct method for assimilating sea surface height data into ocean models with adjustments to the deep circulation abstract there is as yet no consensus an the best method for inserting surface data into ocean models so that appropriate information is transmitted to the deeper layers in a rapid and efficient manner first we consider the correlation of sea surface pressure which is related to sea surface height as measured by altimeters and the surface and subsurface currents within the framework or a four layer quasi geostrophic model we begin by suggesting that the homogenization of potential vorticity q in the unforced layers discussed by rhines and young ensures that the potential vorticity anomalies in the deep ocean are weak it follows that instantaneous q information from thew deep layers may not need to be accurately known in order to reconstruct the deep eddy currents i e climatological q information may be sufficient taking the fields from the model we use the instantaneous surface streamfunction 1 data along with various approximate subsurface q climatologies and attempt to reconstruct the low

radiative transfer mixing models of meteoritic assemblages 1 a spectral mixing model for the expected conditions on asteroid surfaces based on hapke s radiative transfer theory for intimate mixtures is presented this model calculates the visible near infrared reflectance spectrum of an intimate mixture incorporating the modal mineralogy the mineral chemistry the particle size and the degree of space weathering as factors and includes an improved treatment for the spectral effects of coarse grained fe ni metal this model can reproduce the spectra of geologically plausible mixtures of silicate components and meteorites with known mineral abundances chemistry and particle sizes we compare the model spectral effects of the coarse grained fe ni metal naturally present on asteroid surfaces to the spectral effects of submicroscopic iron produced by lunar style space weathering the model spectral effects of large asteroid surface concentrations of coarse grained fe ni metal are similar to the spectral effects of smfe in some cases we model the composition of asteroid 4 vesta and find it to be consistent with a minimally space weathered eucritic composition finally we predict the spectral properties of some example of ordinary chondrite parent bodies when modeled with particle sizes matching the optically dominant particle size of the lunar surface and minimal abundances of smfe these model ordinary chondrite parent bodies plot outside the s iv asteroid field on a band area ratio versus band i center plot we find that a combination of larger particle sizes and increased smfe abundances is the most effective way to move these models into the s iv field

mineralogical records of early planetary processes on the howardite eucrite diogenite parent body with reference to vesta abstract mineralogical information recovered from the howardite eucrite diogenite hed meteorites was employed to reconstruct the history of the parent body and relate it to 4 vesta these interpreted crustal evolution processes were then compared to the expected geological features on the surface of a likely proto planet 4 vesta the original crustal materials of the hed parent body were preserved as mineral grains and lithic clasts but in many eucrites fe mg ratios in pyroxenes were homogenized by diffusion after crystallization the crystallization trend of the protocrust has been deciphered by 1 examining monomict and crystalline samples and using their mineralogical and chemical information to formulate a sequence of crystallization and cooling trends and by 2 reconstructing the original crust prior to cratering events from lithic clasts and mineral fragments in polymict breccias such as howardites and polymict eucrites mineral components are identical both in the individual hed and in polymict breccias and no remnants of primitive materials were preserved in the polymict breccias a layered crust model reconstructed from such breccias consists of an upper crust with extrusive lava like eucrites that have been brecciated and metamorphosed diogenite mantle and cumulate eucrites of varying thickness between them this model can be used to explain the surface geological features of vesta observed from the hubble space telescope a large crater with diogenitic orthopyroxene at the crater floor is consistent with the deepest diogenitic layer of the layered crust model and an underlying olivine layer is expected from early crystallized olivine in the crystal fractionation model the old terrain of eucritic surface materials of vesta can be howardites polymict eucrites or regolith like eucrites produced from eucrites extruded and impacted on the surface partial melting models of eucrites seem to be favored by the rare earth element ree chemistry and experimental studies unfortunately partial melting models have not demonstrated how the hed parent body is converted to a layered crust without producing any metamorphosed primitive material in the layered crust the origin of cumulate eucrites with systematic variation of textures and chemistries of pyroxene can be explained by the layered crust model with excavation and mixing of trapped liquid discovery of basaltic materials with na rich plagioclase and augite in iron meteorites which are the products of partial melting suggests that eucrites may be unique to a body that underwent large scale differentiation and metamorphism

dynamic transfer of simulated altimeter data into subsurface information by a numerical ocean model a global eddy resolving capability to predict the ocean circulation is technologically feasible within the next decade for this purpose the satellite altimeter is the most promising operational source of oceanic data with global coverage but only at the surface a comparable source of subsurface data is not on the horizon this investigation demonstrates the ability of a numerical ocean model to dynamically transfer simulated altimeter data into subsurface information this was done for a variety of dynamical regimes with 1 barotropic baroclinic mixed and episodic instabilities 2 flat bottoms or large amplitude topography 3 relatively vigorous or gentle exchange of energy between the layers and 4 major time scales that are short 60 days long 1 year or both in all cases the pattern of the deep pressure field is much different from the one for the current related variations in the sea surface elevation and sometimes not obviously related to it the model was able to reconstruct the deep pressure field even in situations with energetic shallow and deep circulations baroclinic instability and a vigorous vertical exchange of energy however in such experiments the frequency of updating for the free surface elevation was critical in this study the maximum update interval that allowed successful dynamic surface to subsurface transfer was about half the shortest major time scale smts e g 50 60 days in the experiments with baroclinic instability without knowledge of the deep pressure field numerical predictions of the surface pressure field and the depth of the pycnocline typically were better than climatology for 1 4 to 1 2 the smts but with successful dynamic surface to subsurface transfer forecasts without updating were better than climatology for the smts or more the time scale for predictive skill can be substantially longer than the maximum update interval permitted because the update interval must be short enough to allow decreasing error in the deep pressure field from one free surface update to the next until the error asymptotes at some acceptable level approximately 30 50 in these results forecasts of nondispersive isolated eddies with beta rossby number o 1 demonstrated predictive skill for 3 months or more even when the subsurface initial state was unknown a serendipitous result of the study is some progress in understanding the generation of cyclonic eddies associated with the loop current in the eastern gulf of mexico section 5 5

synthetic temperature profiles derived from geosat altimetry comparison with air dropped expendable bathythermograph profiles synthetic temperature profiles are computed from altimeter derived sea surface heights in the gulf stream region the required relationships between surface height dynamic height at the surface relative to 1000 dbar and subsurface temperature are provided from regression relationships between dynamic height and amplitudes of empirical orthogonal functions eofs of the vertical structure of temperature derived by de witt 1987 relationships were derived for each month of the year from historical temperature and salinity profiles from the region surrounding the gulf stream northeast of cape hatteras sea surface heights are derived using two different geoid estimates the feature modeled geoid and the air dropped expendable bathythermograph axbt geoid both described by carnes et al 1990 the accuracy of the synthetic profiles is assessed by comparison to 21 axbt profile sections which were taken during three surveys along 12 geosat erm ground tracks nearly contemporaneously with geosat overflights the primary error statistic considered is the root mean square rms difference between axbt and synthetic isotherm depths the two sources of error are the eof relationship and the altimeter derived surface heights eof related and surface height related errors in synthetic temperature isotherm depth are of comparable magnitude each translates into about a 60 m rms isotherm depth error or a combined 80 m to 90 m error for isotherms in the permanent thermocline eof related errors are responsible for the absence of the near surface warm core of the gulf stream and for the reduced volume of eighteen degree water in the upper few hundred meters of apparently older cold core rings in the synthetic profiles the overall rms difference between surface heights derived from the altimeter and those computed from axbt profiles is 0 15 dyn m when the feature modeled geoid is used and 0 19 dyn m when the axbt geoid is used the portion attributable to altimeter derived surface height errors alone is 0 03 dyn m less for each in most cases the deeper structure of the gulf stream and eddies is reproduced well by vertical sections of synthetic temperature with largest errors typically in regions of high horizontal gradient such as across rings and the gulf stream front

olivine rich exposures at bellicia and arruntia craters on 4 vesta from dawn fc we present an analysis of olivine rich exposures at bellicia and arruntia craters using dawn framing camera fc color data our results confirm the existence of olivine rich materials at these localities as described by ammannito et al 2013a using visual infrared spectrometer vir data analyzing laboratory spectra of various howardite eucrite diogenite meteorites high ca pyroxenes olivines and olivine orthopyroxene mixtures we derive three fc spectral band parameters that are indicators of olivine rich materials combining the three band parameters allows us for the first time to reliably identify sites showing modal olivine contents 40 the olivine rich exposures at bellicia and arruntia are mapped using higher spatial resolution fc data the exposures are located on the slopes of outer inner crater walls on the floor of arruntia in the ejecta as well as in nearby fresh small impact craters the spatial extent of the exposures ranges from a few hundred meters to few kilometers the olivine rich exposures are in accordance with both the magma ocean and the serial magmatism model e g righter and drake 1997 yamaguchi et al 1997 however it remains unsolved why the olivine rich materials are mainly concentrated in the northern hemisphere approximately 36 42 n 46 74 e and are almost absent in the rheasilvia basin

sea surface salinity structure of the meandering gulf stream revealed by smos sensor measurements from the soil moisture ocean salinity smos satellite acquired during 2012 in the western north atlantic are used to reveal the evolution of the sea surface salinity sss structure of the meandering gulf stream with an unprecedented space and time resolution combined with in situ surface and profile measurements satellite derived surface currents sea surface height ssh surface temperature sst and chlorophyll chl data smos sss observations are shown to coherently delineate meanders pinching off from the current to form well identified salty warm and fresh cold core gulf stream rings a covariance analysis at two locations along the separated gulf stream path south of nova scotia and in the gulf stream extension reveals a systematically higher correlation between sss and sea level variability than between sst and ssh during the warmer half of the year within 75 w 40 w 30 n 50 n chl concentration is also found to significantly depend on the sss as sst increases above 20 c

three dimensional spectral analysis of compositional heterogeneity at arruntia crater on 4 vesta using dawn fc abstract we introduce an innovative three dimensional spectral approach three band parameter space with polyhedrons that can be used for both qualitative and quantitative analyzes improving the characterization of surface compositional heterogeneity of 4 vesta it is an advanced and more robust methodology compared to the standard two dimensional spectral approach two band parameter space the dawn framing camera fc color data obtained during high altitude mapping orbit resolution 60 m pixel is used the main focus is on the howardite eucrite diogenite hed lithologies containing carbonaceous chondritic material olivine and impact melt the archived spectra of heds and their mixtures from relab hoserlab and usgs databases as well as our laboratory measured spectra are used for this study three dimensional convex polyhedrons are defined using computed band parameter values of laboratory spectra polyhedrons based on the parameters of band tilt r0 92 m r0 96 m mid ratio r0 75 m r0 83 m r0 83 m r0 92 m and reflectance at 0 55 m r0 55 m are chosen for the present analysis an algorithm in idl programming language is employed to assign fc data points to the respective polyhedrons the arruntia region in the northern hemisphere of vesta is selected for a case study because of its geological and mineralogical importance we observe that this region is eucrite dominated howarditic in composition the extent of olivine rich exposures within an area of 2 5 crater radii is 12 larger than the previous finding thangjam g et al 2014 meteorit planet sci 49 1831 1850 lithologies of nearly pure cm2 chondrite olivine glass and diogenite are not found in this region although there are no unambiguous spectral features of impact melt the investigation of morphological features using fc clear filter data from low altitude mapping orbit resolution 18 m pixel suggests potential impact melt features inside and outside of the crater our spectral approach can be extended to the entire vestan surface to study the heterogeneous surface composition and its geology

discovery of a basaltic asteroid in the outer main belt visible and near infrared spectroscopic observations of the asteroid 1459 magnya indicate that it has a basaltic surface magnya is at 3 15 astronomical units au from the sun and has no known dynamical link to any family to any nearby large asteroid or to asteroid 4 vesta at 2 36 au which is the only other known large basaltic asteroid we show that the region of the belt around magnya is densely filled by mean motion resonances generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as magnya magnya may represent a rare surviving fragment from a larger differentiated planetesimal that was disrupted long ago

diagnosis of vertical velocities in the upper ocean from high resolution sea surface height 1 a surface quasi geostrophy based esqg method to diagnose the vertical velocity field from sea surface height ssh is assessed using high resolution simulations these simulations concern a turbulent eddy field with large rossby numbers and energetic wind driven motions results indicate that low frequency vertical velocities and also horizontal motions can be reconstructed within a range of scales between 20 km and 400 km from the surface down to 500 m the only information needed is a single high resolution ssh snapshot and information on the large scale vertical stratification inertial motions are naturally filtered because they do not contaminate ssh as we demonstrate these results are encouraging and further strengthen previous studies using the esqg method they indicate that access to high resolution ssh may represent a major advance to retrieve horizontal and vertical fluxes of any tracer in the upper ocean

surface lithologic heterogeneity of asteroid 4 vesta abstract high precision spectrophotometry of 4 vesta the third largest asteroid was used to establish the surface composition of this body and to investigate mineralogical variations across its surface the average surface of vesta is analogous to howardite and or polymict eucrite assemblages regolith derived members of the hed meteorite suite which consist of a eucrite matrix containing differing amounts of a diogenite component color and or spectral changes which exhibit a consistent relationship to rotational phasing are evident in 16 of 18 studies of vesta dating back to 1929 including the present work after elimination of possible sources of spurious spectral or color changes it is concluded that these variations arise from hemispheric variations in surface materials and hence provide a means of spatially resolving subhemispheric compositional units on the surface of vesta the background surface of vesta is a relatively dark howardite or polymict eucrite pyroxene plagioclase assemblage with several compositionally distinct bright regions clustered in one hemisphere viewed around the maximum in vesta s lightcurve these include what appears to be an olivine bearing unit suggested name leslie formation located near vesta s equator which probably represents an impact basin and or its associated ejecta that penetrated through the basaltic crust other high albedo compositional units including an apparently low calcium eucrite region and several diogenite pyroxenite regions at least one located near the southern pole may be smaller shallower impact basins by analogy to the eucrite meteorites which represent surface flows or shallow intrusions and which constitute the major component of the regolith derived howardites and polymict eucrites we conclude that the howardite polymict eucrite units represent a regolith gardened original surface of vesta it is probable that the low albedo of the background surface on vesta is due to an age related darkening effect similar to that inferred from the galileo images of gaspra and ida this mechanism is consistent with the correlation of absorption feature intensity with the lightcurve vesta appears to have an old eucritic surface darkened with age and represented among the meteorites by the regolith derived howardites and polymict eucrites on which several impacts on one hemisphere have exposed fresher brighter diogenite and olivine bearing material based on qualitative analysis of the mineralogical variations as a function of rotation a generalized lithologic map of vesta was produced there is reasonable control on the longitude of lithologic features but little control on their latitudes except where specifically noted in producing this map discrete circular features were used on the plausible assumption that impacts have been the most important geologic process on this surface for most of the age of the solar system the shape of the features has thus been assumed rather than derived and is subject to future revision as data improve

mineralogy of asteroid 1459 magnya and implications for its origin detailed near infrared spectral observations of asteroid 1459 magnya reveal an asteroid that is primarily composed of pyroxene and plagioclase feldspar confirming earlier suggestions that magnya has a basaltic composition the average magnya spectrum for march 23 2002 has a band i center of 0 926 m and a band ii center of 1 938 m observations over 4 1 hours show little variation in band center positions the feldspar to pyroxene ratio is 0 6 on magnya s surface comparing magnya with the spectral parameters from 4 vesta shows discordant pyroxene chemistries magnya s pyroxenes contain 10 mol less fs than vesta s pyroxenes this suggests that magnya originated from a parent body other than 4 vesta and that its progenitor formed in a more chemically reduced region of the solar nebula within the asteroid belt

reconstructing the ocean interior from high resolution sea surface information abstractwhen evaluated against the 1 30 resolution submesoscale resolving ofes model outputs the previously published interior surface quasigeostrophic method from the 2013 study by wang et

new metallogenic model of telescoped eocene miocene au u epithermal mineral deposit in the placer de guadalupe district chihuahua mexico abstract the chronological repartition of mineral deposits in mexico and the southern usa coincides with the distribution of the three main volcanic pulses of the sierra madre occidental these pulses are eocene to early miocene in age suggesting that a broad migration occurred from northwest to southeast where the last ignimbrite flare up occurred the most fertile event occurred from 36 to 28 ma and produced all of the largest ag au mining districts the placer de guadalupe au u district contain a unique association of metals with high variations in their u au ratios that are not common worldwide the uraninite population dated by wells 1930 yielded an age of ca 36 ma which is comparable to that of the volcanic intrusions and dykes dated in the district yielding ages of ca 36 ma altered uraninite cemented by gold sheets provide an age of 21 ma which is interpreted to be the age of the gold epithermal event studies of fluid inclusions in the quartz and calcite cements formed in the gold event indicate the presence of immiscible magmatic brines and co2 homogenization temperatures by halite melting range from 268 c to 305 c and 266 6 c to 283 c with salinities ranging from 35 9 to 38 9 and 36 0 to 37 5 wt eq nacl in the quartz and calcite stages respectively c o isotopic compositions of u and au calcite cements suggest a trend of low temperature alteration caused by hydrothermal fluids these c o isotopes suggest that during the gold event water rock interaction processes occurred between magmatic fluids and the carbonate host rock ree enrichment in the u calcite cement suggests that la ce enriched carbonatite volcanic formations participated in the mineralizing process the u mineralization event was controlled by 1 a metal and heat source in this case late eocene volcanism and in particular a carbonatite volcanic event 2 an efficient transport mechanism for the large scale input of meteoric water which was channeled heated and u enriched into reactivated crustal eocene faults from a deep u source to a shallow sedimentary chemical trap 3 an effective trap which is represented in this study by the presence of an organic matter rich sedimentary formation the gold mineralization event was characterized by the miocene extensional peak coupled with asthenospheric upwelling which facilitated the melting metamorphism of the lower crust and the expulsion and transport of large amounts of co2 bearing fluids to a shallow crustal level through the reactivated crustal laramide thrust faults the fluids interactions with the entire stratigraphic column from the grenvillian to the late triassic basement favored the leaching of gold and the enrichment of co2 bearing fluids gold deposition appears to be related to boiling but was ultimately favored by water rock interaction with u mineralization and the upper plomosas shale study of the au u placer de guadalupe deposit reveals evidence of a new miocene metallogenic event in central and northern mexico its genetic relationship with the basin and range bnr and rio gande rift rgr in usa and its transition from post orogenic to miocene intraplate extension in mexico provides a new perspective regarding the exploration of miocene gold epithermal deposits in northern mexico and the southern usa

pyroxene spectroscopy revisited spectral compositional correlations and relationship to geothermometry the authors wish to thank the various agencies which have provided the necessary support for this project including grants in aid of research from sigma xi the scientific research society to e a c the geological society of america grant 3741 87 to e a c and nasa planetary geology and geophysics grant nagw 642 to m j g

spectral properties and rotational spectral heterogeneity of 433 eros composite spectra of different rotational aspects of the s asteroid 433 eros were assembled from previous studies covering the wavelength range 0 33 2 5 m these data allow us to measure significant attributes of eros s spectrum its mafic mineral absorptions and the degree and nature of compositional heterogeneity of its surface we also evaluated previous s asteroid taxonomies using independent methods and from this test determined that the taxonomy of gaffey et al 1993 provides a sound basis for relating eros to other s asteroids on average eros resembles the s iv asteroids which bear the closest resemblance to ordinary chondrites in mafic mineralogy however eros also exhibits distinct rotational spectral variations comparable to the greatest yet recognized on an s asteroid one side of the asteroid has a shorter wavelength 1 m absorption and a stronger 2 m absorption than the global average and is interpreted to be richer in pyroxene the opposite face has a longer wavelength 1 m absorption and a weaker 2 m absorption and is interpreted to be richer in olivine the pyroxene rich side coincides with a facet like face identified in radar studies and the olivine rich side coincides with a convex shaped face each side of the asteroid exhibits spectral affinities with a different spectral class of s asteroids demonstrating that such subdivisions of s asteroids represent different parts of a compositional continuum high spatial resolution measurement of the mineralogic and elemental compositions and especially the geologic settings of these different materials by the near earth asteroid rendezvous mission will provide a great advance in the understanding of the origin and evolution of a candidate ordinary chondrite parent body

on the transfer function between surface fields and the geostrophic stream function in the mediterranean sea abstractthe real transfer function and the phase shift between sea surface height ssh and sea surface buoyancy ssb were estimated from the output of a realistic eddy resolving model of the mediterranean sea circulation the analysis of their temporal evolution unveiled the existence of a clear seasonal cycle closely related to that of the mixed layer depth the phase shifts between ssh and ssb attain their minimum for deep mixed layers which is different from zero besides the spectral slope of the transfer function at scales shorter than 100 km fluctuates between k 1 and k 2 for deep mixed layers it is close to k 1 as predicted by the surface quasigeostrophic sqg solution at longer wavelengths it is approximately constant under the different environmental conditions in all of the subbasins analyzed with the exception of the gulf of lions the capability to observe sea surface temperature sst from satellites motivated the extension of this analysis to sst and ssh results showed a similar q

global ocean current reconstruction from altimetric and microwave sst measurements ocean currents are a key component to understanding many oceanic and climatic phenomena and knowledge of them is crucial for both navigation and operational applications currently they are derived from sea surface height ssh measurements provided by altimeters however distances between tracks and the limited number of available altimeters lead to errors in the accurate location of oceanic currents in this study we investigate the capability of sea surface temperature sst observations to reconstruct surface currents at a global scale the methodology we use consists of estimating the stream function by taking the phase from sst and the spectrum of ssh and then comparing it with altimetric measurements results reveal that sst provided by microwave radiometers can be used to retrieve ocean currents during winter near the major extratropical current systems which are characterized by an intense mesoscale activity and the presence of strong thermal gradients we have also found that surface ocean current reconstruction based on surface quasi geostrophic approach can be improved if the information about the energy spectrum provided by altimeters is used this points to the development of a new method of reconstructing ocean currents based on the combination of the phase of sst images with the energy spectrum derived from along track altimetric measurements

retrieving density and velocity fields of the ocean s interior from surface data using the interior surface quasigeostrophic isqg method the density and horizontal velocity fields of the ocean s interior can be retrieved from surface data this method was applied to the simple ocean data assimilation soda and the hybrid coordinate ocean model hycom navy coupled ocean data assimilation ncoda reanalysis data sets the input surface data include sea surface height ssh sea surface temperature sst sea surface salinity sss and a region averaged stratification the retrieved subsurface fields are compared with reanalysis data for three tested regions and the results indicate that the isqg method is robust the isqg method is particularly successful in the energetic regions like the gulf stream region with weak stratification and the kuroshio region with strong correlation between sea surface density ssd and ssh it also works though less satisfactorily in the agulhas leakage region the performance of the isqg method in retrieving subsurface fields varies with season and peaks in winter when the mixed layer is deeper and stratification is weaker in addition higher resolution data may facilitate the isqg method to achieve a more successful reconstruction for the velocity retrieval our results suggested that the isqg method can be used to reconstruct the ocean interior from the satellite derived ssh sst and sss data in the near future

surface quasigeostrophic solutions and baroclinic modes with exponential stratification abstractthe author derives baroclinic modes and surface quasigeostrophic sqg solutions with exponential stratification and compares the results to those obtained with constant stratification the sqg solutions with exponential stratification decay more rapidly in the vertical and have weaker near surface velocities this then compounds the previously noted problem that sqg underpredicts the velocities associated with a given surface density anomaly the author also examines how the sqg solutions project onto the baroclinic modes with constant stratification sqg waves larger than deformation scale project primarily onto the barotropic mode and to a lesser degree onto the first baroclinic mode however with exponential stratification the largest projection is on the first baroclinic mode the effect is even more pronounced over rough bottom topography therefore large scale sqg waves will look like the first baroclinic mode and vice versa with realistic stratification

quasigeostrophic turbulence with explicit surface dynamics application to the atmospheric energy spectrum abstract the horizontal wavenumber spectra of wind and temperature near the tropopause have a steep 3 slope at synoptic scales and a shallower 5 3 slope at mesoscales with a transition between the two regimes at a wavelength of about 450 km here it is demonstrated that a quasigeostrophic model driven by baroclinic instability exhibits such a transition near its upper boundary analogous to the tropopause when surface temperature advection at that boundary is properly resolved and forced to accurately represent surface advection at the upper and lower boundaries the vertical structure of the model streamfunction is decomposed into four parts representing the interior flow with the first two neutral modes and each surface with its green s function solution resulting in a system with four prognostic equations mean temperature gradients are applied at each surface and a mean potential vorticity gradient consisting both of and vertical shear is applied in the interior the system exhibits three f

the scales and equilibration of midocean eddies freely evolving flow quasigeostrophic turbulence theory and numerical simulation are used to study the mechanisms determining the scale structure and equilibration of mesoscale ocean eddies the present work concentrates on using freely decaying geostrophic turbulence to understand and explain the vertical and horizontal flow of energy through a stratified horizontally homogeneous geostrophic fluid it is found that the stratification profile in particular the presence of a pycnocline has significant qualitative effects on the efficiency and spectral pathways of energy flow specifically with uniform stratification energy in high baroclinic modes transfers directly quickly within a few eddy turnaround times and almost completely to the barotropic mode by contrast in the presence of oceanlike stratification kinetic energy in high baroclinic modes transfers intermediately to the first baroclinic mode whence it transfers inefficiently and incompletely to the barotropic mode the efficiency of transfer to the barotropic mode is reduced as the pycnocline is made increasingly thin the b effect on the other hand improves the efficiency of barotropization but for oceanically realistic parameters this effect is relatively unimportant compared to the effects of nonuniform stratification finally the nature of turbulent cascade dynamics is such as to lead to a concentration of first baroclinic mode kinetic energy near the first radius of deformation which in the case of a nonuniform and oceanically realistic stratification has a significant projection at the surface this may in part explain recent observations of surface eddy scales by topex poseidon satellite altimetry which indicate a correlation of surface height variance with the scale of the first deformation radius

can oceanic submesoscale processes be observed with satellite altimetry high resolution 2 km and hourly observations of surface currents from high frequency radars are analyzed in terms of sea level anomalies sla and compared with data from two satellite altimeter ground tracks purpose is to investigate whether ocean submesoscale processes can be observed with satellite altimetry our results highlight two major problems that must be overcome before being able to resolve submesoscale processes with altimetry i signal contamination from high frequency motions and in particular from incoherent internal tides near inertial oscillations have no effect on sla and ii measurement noise which prevents the computation of accurate cross track currents on scales o 10 km the latter may be overcome by future satellite altimeter missions but the former will require taking into account the effect of mesoscale variability on internal tide propagation in regions where internal tides are significant citation chavanne c p and p klein 2010 can oceanic submesoscale processes be observed with satellite altimetry geophys res lett 37 l22602 doi 10 1029 2010gl045057

quantified mineralogical evidence for a common origin of 1929 kollaa with 4 vesta and the hed meteorites abstract in this paper we present the first correlation of derived mineral abundances of v class asteroid 1929 kollaa 4 vesta and the hed meteorites we demonstrate that 1929 kollaa has a basaltic composition consistent with an origin within the crustal layer of 4 vesta and show a plausible genetic connection between kollaa and the cumulate eucrite meteorites these data support the proposed delivery mechanism of hed meteorites to the earth from vesta and provide the first mineralogical constraint derived from the observation of a small v class vesta family asteroid on the crustal thickness of 4 vesta

gaussian analysis of temperature effects on the reflectance spectra of mafic minerals in the 1 μm region gaussian band fitting analysis has been applied to the reflectance spectra of mafic silicates which are of geologic importance throughout much of the solar system reflectance spectra obtained over a sample temperature range of 80 to 448 k of olivine clinopyroxene and orthopyroxene were used in order to characterize the spectral changes in the 1 m wavelength region of these minerals as a function of temperature four gaussians are required to characterize the olivine while two gaussians are necessary to characterize both the orthopyroxene and clinopyroxene the trends of the individual gaussian parameters integrated area width and center position are presented as a function of temperature for each mineral the characterization by gaussian analysis of the 1 m absorption feature of all minerals yields consistent trends in center position integrated area and width that may prove useful in quantitative determination of these minerals in mineral mixtures the gaussian analysis of olivine for the three primary band components is qualitatively consistent with previous crystal field transition assignments of fe2 in the m 1 and m 2 crystallographic sites the trends of the determined olivine gaussian center positions imply that site symmetry is more important in determining transition energies than metal oxygen distances the result of the gaussian analysis for orthopyroxene is consistent with the need for two gaussians to describe an asymmetric band the gaussian analysis of the clinopyroxene is consistent with previous assignments of crystal field transitions due to fe2 in the m 1 and m 2 crystallographic sites

vesta vestoids and the howardite eucrite diogenite group relationships and the origin of spectral differences spectra of asteroid 4 vesta and 21 small estimated diameters less than 10 km asteroids with vesta like spectral properties vestoids were measured at visible and near infrared wavelengths similar to0 44 to similar to1 65 mum all of the measured small asteroids except for 2579 spartacus have reflectance spectra consistent with surface compositions similar to eucrites and howardites and consistent with all being derived from vesta none of the observed asteroids have spectra similar to diogenites we find no spectral distinction between the 15 objects tabulated as members of the vesta dynamical family and 6 of the 7 sampled non family members that reside just outside the semi major axis a eccentricity e and inclination i region of the family the spectral consistency and close orbital a e i match of these non family objects to vesta and the vesta family imply that the true bounds of the family extend beyond the subjective cut off for membership asteroid 2579 spartacus has a spectrum consistent with a mixture of eucritic material and olivine spartacus could contain olivine rich material from vesta s mantle or may be unrelated to vesta altogether laboratory measurements of the spectra of eucrites show that samples having nearly identical compositions can display a wide range of spectral slopes finer particle sizes lead to an increase in the slope which is usually referred to as reddening this range of spectral variation for the best known meteoritic analogs to the vestoids regardless of whether they are actually related to each other suggests that the extremely red spectral slopes for some vestoids can be explained by very fine grained eucritic material on their surfaces

vestan lithologies mapped by the visual and infrared spectrometer on dawn we present global lithological maps of the vestan surface based on dawn mission s visible infrared vir spectrometer acquisitions with a spatial sampling of 200 m the maps confirm the results obtained with the data set acquired by vir with a spatial sampling of 700 m that the reflectance spectra of vesta s surface are dominated by pyroxene absorptions that can be interpreted within the context of the distribution of howardites eucrites and diogenites heds the maps also partially agree with the ground and hubble space telescope observations they confirm the background surface being an assemblage of howardite or polymict eucrite as well as the location of a diogenitic rich spot however there is no evidence of extended olivine rich regions in the equatorial latitudes diogenite is revealed on the rheasilvia basin floor indicating that material of the lower crust mantle was exposed vir also detected diogenites along the scarp of matronalia rupes and the rims of severina and a nearby unnamed crater and as ejecta of antonia crater the diogenite distribution is fully consistent with petrological constraints although the mapped distribution does not provide unambiguous constraints it favors the hypothesis of a magma ocean

three dimensional reconstruction of oceanic mesoscale currents from surface information the ability to reconstruct the three dimensional 3d dynamics of the ocean by an effective version of surface quasi geostrophy esqg is examined using the fact that surface density plays an analogous role as interior potential vorticity pv the esqg method consists in inverting the qg pv generated by sea surface density only we also make the extra assumption that sea surface temperature sst anomalies fully represent surface density anomalies this approach requires a single snapshot of sst and the setup of two parameters the mean brunt vaisala frequency and a parameter that determines the energy level at the ocean surface the validity of this approach is tested using an ocean general circulation model simulation representing the north atlantic in winter it is shown that the method is quite successful in reconstructing the velocity field at the ocean surface for mesoscales between 30 and 300 km the esqg framework can also be applied to reconstruct subsurface fields using surface information results show that the reconstruction of velocities and vorticity from surface fields is reasonably good for the upper 500 m and that the success of the method mainly depends on the quality of the sst as a proxy of the density anomaly at the base of the mixed layer this situation happens after a mixed layer deepening period therefore the ideal situation for the application of this method would be after strong wind events

reconstructing the ocean s interior from surface data a new method is proposed for extrapolating subsurface velocity and density fields from sea surface density and sea surface height ssh in this the surface density is linked to the subsurface fields via the surface quasigeostrophic sqg formalism as proposed in several recent papers the subsurface field is augmented by the addition of the barotropic and first baroclinic modes whose amplitudes are determined by matching to the sea surface height pressure after subtracting the sqg contribution an additional constraint is that the bottom pressure anomaly vanishes the method is tested for three regions in the north atlantic using data from a high resolution numericalsimulation the decomposition yields strikinglyrealistic subsurfacefields it is particularly successful in energetic regions like the gulf stream extension and at high latitudes where the mixed layer is deep but it also works in less energetic eastern subtropics the demonstration highlights the possibility of reconstructing three dimensional oceanic flows using a combination of satellite fields for example seasurfacetemperature sst andssh andsparse orclimatological estimatesoftheregionaldepthresolveddensity themethodcouldbefurtherelaboratedtointegrateadditionalsubsurfaceinformation such as mooring measurements

a global analysis of sverdrup balance using absolute geostrophic velocities from argo using observations from the argo array of profiling floats the large scale circulation of the upper 2000 decibars db of the global ocean is computed for the period from december 2004 to november 2010 the geostrophic velocity relative to a reference level of 900db is estimated from temperature and salinity profiles and the absolute geostrophic velocity at the reference level is estimated from the trajectory data provided by the floats combining the two gives the absolute geostrophic velocity on 29 pressure surfaces spanning the upper 2000db of the global ocean these velocities together with satellite observations of wind stress are thenusedtoevaluatesverdrupbalance thesimplecanonicaltheoryrelatingmeridionalgeostrophictransport to wind forcing observed transports agree well with predictions based on the wind field over large areas primarily in the tropics and subtropics elsewhere especially at higher latitudes and in boundary regions sverdrup balance does not accurately describe meridional geostrophic transports possibly due to the increased importance of the barotropic flow nonlinear dynamics and topographic influence thus while it provides an effective framework for understanding the zero order wind driven circulation in much of the global ocean sverdrup balance should not be regarded as axiomatic

composition and mineralogy of dark material units on vesta vesta is the asteroid with the largest albedo variation among the known rocky solar system objects and shows a widespread occurrence of dark material dm and bright material bm units in the first observation phases by the dawn spacecraft two main extensions of low albedo areas were identified on vesta and found to be closely correlated with carbonaceous oh rich material in this work we use the hyperspectral data provided by the vir dawn imaging spectrometer onboard dawn to detect and analyze individual well defined dark material units we define dm units assuming a relative criterion i e reflectance lower than the surroundings by coupling visible and infrared images of the same area we are able to select real dark material units discarding false detections created by shadowing effects a detailed final catalogue of 123 dark units is presented containing the geographical parameters and the main spectral characteristics for each unit independently of the geological context of the dark units all dms show similar spectral properties dominated by the pyroxene absorption features as is the average spectrum of vesta this finding suggests a similar composition with the presence of darkening agents that also weaken pyroxene band depths the majority 90 of the dm units shows a positive correlation between low albedo and an oh band centered at 2 8 lm confirming the hypothesis that the darkening agents are carbonaceous chondrites probably delivered by low velocity impacts of primitive asteroids a comparison with laboratory spectra allows us to better constrain the size and the composition of the darkening agents these dm areas seem to be made of eucritic material the regolith grain size seems to be nearly constant around an average value of 25 lm and is quite homogenous at least in the first hundreds of meters beneath the vesta surface suggesting similar processing mechanisms for both dm and bm

a two dimensional gravest empirical mode determined from hydrographic observations in the subantarctic front abstract south of australia where the baroclinicity in the subantarctic front extends almost to the seafloor the geopotential height of the sea surface and the vertical acoustic travel time exhibit a tight empirical relationship to each other and to the entire vertical structure of temperature t p salinity s p and specific volume anomaly p measurements of provide proxy estimates of the profiles tg p sg p and g p based on a two dimensional gravest empirical mode gem representation of the vertical structure fitted to 212 hydrographic stations a seasonal model was fitted in the near surface layers using additional historical data at each depth in the range 150 3000 dbar more than 96 of the variance in both the t and fields is captured by the gem representation during the subantarctic flux and dynamics experiment mar 1995 mar 1997 inverted echo sounders ies and current meters were moored in a 2d array along the woce sr3 transect south of australia at each i

estimating subsurface velocities from surface fields with idealized stratification abstracta previously published method by wang et al for predicting subsurface velocities and density from sea surface buoyancy and surface height is extended by incorporating analytical solutions to make the vertical projection one solution employs exponential stratification and the second has a weakly stratified surface layer approximating a mixed layer the results are evaluated using fields from a numerical simulation of the north atlantic the simple exponential solution yields realistic subsurface density and vorticity fields to nearly 1000 m in depth including a mixed layer improves the response in the mixed layer itself and at high latitudes where the mixed layer is deeper it is in the mixed layer that the surface quasigeostrophic approximation is most applicable below that the first baroclinic mode dominates and that mode is well approximated by the analytical solution with exponential stratification

do altimeter wavenumber spectra agree with the interior or surface quasigeostrophic theory in high eddy energy regions it is generally assumed that sea level wavenumber spectra compare well with quasigeostrophic qg turbulence models and that spectral slopes are close to the expected k 5 law this issue is revisited here sea level wavenumber spectra in the gulf stream kuroshio and agulhas regions are estimated using the most recent altimeter datasets the ocean topography experiment topex poseidon jason 1 the environmental satellite envisat and the geosat follow on the authors show that spectral slopes in the mesoscale band are significantly different from a k 5 law in disagreement with the qg turbulence theory however they very closely follow a k 11 3 slope which indicates that the surface quasigeostrophic theory sqg is a much better dynamical framework than the qg turbulence theory to describe the ocean surface dynamics because of the specific properties of the sqg theory these results offer new perspectives for the analysis and interpretation of satellite data

revisiting spectral parameters of silicate bearing meteorites visible and near infrared reflectance spectra of a sample of silicate bearing meteorites have been used to evaluate the spectral parameters space defined in the pioneering work of gaffey et al 1993 the studied sample consisted of 91 ordinary chondrites 47 basaltic achondrites and 21 different laboratory mixtures obtained from the relab database our results indicate that the spectral parameter space in particular the bar versus band i center is not suitable enough to identify the mineralogy of meteorites and asteroids the grain size of the sample also appears as a very sensitive parameter and can play an important role in locating an object in the spectral parameter space finally the application of our study to the question of a genetic link between v type asteroids and hed meteorites shows that these bodies plot in distinct regions in the bar versus band i center space this result further confirms that those spectral parameters cannot uniquely define the mineralogy of a sample

reconstruction of ocean s interior from observed sea surface information observational surface data are used to reconstruct the ocean s interior through the interior surface quasigeostrophic isqg method the input data include the satellite derived sea surface height satellite derived sea surface temperature satellite derived or argo based sea surface salinity and an estimated stratification of the region the results show that the isqg retrieval of subsurface density anomalies is quite promising compared to argo profile data at 1000 m depth the directions of retrieved velocity anomalies are comparable to those derived from argo float trajectories the reconstruction using surface density input field approximated only by sst with constant sss performs less satisfactorily than that taking into account the contribution of sss perturbations suggesting that the observed sss information is important for the application of the isqg method better reconstruction is obtained in the warm season than in the cold season which is probably due to the stronger stratification in the warm season that confines the influence of the biases in the surface input data especially sss in a shallow layer the comparison between the performance of isqg with argo based sss input and that with satellite derived sss input suggests that the biases in the sss products could be a major factor that influences the isqg performance with reduced biases in satellite derived sss in the future the measurement based isqg method is expected to achieve better reconstruction of ocean interior and thus is promising in practical application

dynamics of the upper oceanic layers in terms of surface quasigeostrophy theory in this study the relation between the interior and the surface dynamics for nonlinear baroclinically unstable flows is examined using the concepts of potential vorticity first it is demonstrated that baroclinic unstable flows present the property that the potential vorticity mesoscale and submesoscale anomalies in the ocean interior are strongly correlated to the surface density anomalies then using the invertibility of potential vorticity the dynamics are decomposed in terms of a solution forced by the three dimensional 3d potential vorticity and a solution forced by the surface boundary condition in density it is found that in the upper oceanic layers the balanced flow induced only by potential vorticity is strongly anticorrelated with that induced only by the surface density with a dominance of the latter the major consequence is that the 3d balanced motions can be determined from only the surface density and the characteristics of the basin scale stratification by solving an elliptic equation these properties allow for the possibility to reconstruct the 3d balanced velocity field of the upper layers from just the knowledge of the surface density by using a simpler model that is an effective surface quasigeostrophic model all these results are validated through the examination of a primitive equation simulation reproducing the dynamics of the antarctic circumpolar current

new cnes cls09 global mean dynamic topography computed from the combination of grace data altimetry and in situ measurements 1 an accurate knowledge of the ocean mean dynamic topography mdt is mandatory for the optimal use of altimetric data including their assimilation into operational ocean forecasting systems a new global 1 4 resolution mdt was computed for the 1993 1999 time period with improved data and methodology compared to the previous rio05 mdt field first a large scale mdt is obtained from the cls01 altimetric mean sea surface and a recent geoid model computed from 4 5 years of grace gravity recovery and climate experiment data altimetric sea level anomalies and in situ measurements are then combined to compute synthetic estimates of the mdt and the corresponding mean currents while the rio05 mdt was based on 10 years of in situ dynamic heights and drifting buoy velocities the new field benefits from an enlarged data set of in situ measurements ranging from 1993 to 2008 and includes all hydrological profiles from the argo array moreover the processing of the in situ data has been updated a new ekman model was developed to extract the geostrophic velocity component from the drifting buoy measurements the handling of hydrologic measurements has also been revisited compared to the previous rio05 solution the new global mdt resolves much stronger gradients in western boundary currents with mean velocities being doubled in some places moreover in comparison to several other recent mdt estimates we find that the new cnes cls09 mdt is in better agreement with independent in situ observations

presidential address presented 2000 august 28 chicago illinois usa the eucrite vesta story many lines of evidence indicate that meteorites are derived from the asteroid belt but in general identifying any meteorite class with a particular asteroid has been problematical one exception is asteroid 4 vesta where a strong case can be made that it is the ultimate source of the howardite eucrite diogenite hed family of basaltic achondrites visible and near infrared reflectance spectra first suggested a connection between vesta and the basaltic achondrites experimental petrology demonstrated that the eucrites the relatively unaltered and unmixed basaltic achondrites were the product of approximately a 10 melt studies of siderophile element partitioning suggested that this melt was the residue of an asteroidal scale magma ocean mass balance considerations point to a parent body that had its surface excavated but remains intact modern telescopic spectroscopy has identified kilometer scale vestoids between vesta and the 3 1 orbit orbit resonance with jupiter dynamical simulations of impact into vesta demonstrate the plausibility of ejecting relatively unshocked material at velocities consistent with these astronomical observations hubble space telescope images show a 460 km diameter impact basin at the south pole of vesta it seems that nature has provided multiple free sample return missions to a unique asteroid major challenges are to establish the geologic context of the hed meteorites on the surface of vesta and to connect the remaining meteorites to specific asteroids

detection of new olivine rich locations on vesta abstract the discovery of olivine on vesta s surface by the vir imaging spectrometer onboard the dawn space mission has forced us to reconsider our views of vestan petrogenetic models olivines were expected to be present in the interior of vesta in the mantle of a vertically layered body as invoked by the magma ocean models or at the base or within the mantle crust boundary as proposed by fractionation models olivines have been detected by vir dawn in two wide areas near arruntia and bellicia regions located in the northern hemisphere interestingly these olivine rich terrains are far from the rheasilvia and the more ancient veneneia basins which are expected to have excavated the crust down to reach the mantle in this work we present our attempts to identify other undetected olivine rich areas on vesta by using spectral parameters sensitive to olivine such as the band area ratio bar and other specific parameters created for the detection of olivines on mars forsterite fayalite and a generic olivine index as a preliminary step we calibrated these parameters by means of vis ir spectra of different hed meteorite samples behaviors versus sample grain size and albedo were analyzed and discussed we selected the bar and the forsterite index as the best parameters that can be used on vesta a cross correlation analysis has been applied in order to detect olivine signature on the vir hyperspectral cubes these detections have then been confirmed by an anti correlation analysis between the bar and one of the olivine parameters independent of the first method applied in agreement with the recent discovery arruntia and bellicia were found to be as the most olivine rich areas i e where the parameter values are strongest in addition we detected 6 new regions all but one located in the vesta north hemisphere this result confirms again that the old petrogenetic models cannot be straightforwardly applied to vesta and should be reshaped in the view of these new detections an alternative and very recent option can be represented by the model according to which surface eruption of material from the mantle including olivine can reach the surface of vesta

effects of temperature on remotely sensed mineral absorption features laboratory spectral reflectance of mafic silicates has been measured over a temperature range characteristic of solar system objects to study the variation of diagnostic mineral absorption bands this information has become increasingly important with recent improvements in the quality of remotely sensed planetary data and the concurrent increase in sophistication of quantitative and qualitative spectrum analysis techniques in this study visible and near ir reflectance spectra 0 4 2 5 m of pyroxenes and olivine were obtained over a sample temperature range of 80 448 k these are the first published reflectance data for these minerals at temperatures significantly below ambient 300 k additionally thermal radiation emitted from the samples at elevated temperatures was effectively removed disclosing for the first time the high temperature reflectance behavior of pyroxenes in the diagnostic 2 m spectral region as expected from basic physical considerations fe2 crystal field absorptions in all samples become narrower with decreasing temperature the three components of the composite olivine band centered near 1 m become better resolved with decreased temperature and show changes in relative absorption strength there is not however any significant wavelength shift of the olivine reflectance minimum both orthopyroxene and clinopyroxene spectra show dramatic changes in band symmetry with temperature with the greatest change in the longer wavelength edge despite these significant changes in shape little if any change is observed in the wavelength position of reflectance minima of pyroxene absorptions near 1 m the 2 m pyroxene absorptions in contrast demonstrate major shifts of reflectance minima but in different directions in orthopyroxene spectra the band shifts to longer wavelengths with increased temperature while for the clinopyroxene spectra the band shifts to shorter wavelengths this behavior results in greatly improved spectral differentiation of orthopyroxene and clinopyroxene components in a mixture such as a basalt at reduced temperatures application of the results presented here to remote sensing mineral characterization techniques currently in use for determination of pyroxene composition can provide a moderate improvement to quantitative interpretations from 5 to 20 wt feo for orthopyroxenes and 5 wt cao for clinopyroxenes depending on planetary surface temperature

rotational spectral variations of asteroid 8 flora implications for the nature of the s type asteroids and for the parent bodies of the ordinary chondrites abstract the new interpretive calibrations olivine pyroxene abundance spectral signature of chondritic metal grains have been applied to visible and near infrared spectral reflectance data for the typical s type asteroid 8 flora chondritic metal grains do not exhibit the steeply reddened spectral signature previously associated with a nickel iron nife metal phase the conditions required to produce a s type spectral curve from a chondritic material are much more restrictive and improbable than previously supposed five mineralogic and patrologic parameters have been derived for the surface material of flora from the analysis of the spectral reflectance and rotational spectral variations of this object these include bulk mineralogy nife metal olivine pyroxene mafic mineral abundance ol py 2 8 metal nature abundant 50 and coarse grained in the substrate pyroxene composition orthopyroxene f s 50 and or abundant clinopyroxene and spatial mineralogic variations olivine pyroxene ratio and pyroxene composition do not covary in a chondritic manner all of the diagnostic mineralogic properties of the flora surface material indicate that this is a differentiated body none of the derived surface properties unambiguously support a chondritic type material and several contradict any type of undifferentiated assemblage flora is most probably the residual core of an intensely heated thermally evolved and magmatically differentiated planetesimal which was subsequently disrupted the present surface samples layers formed at and near the core mantle boundary in the parent body several lines of evidence suggest that the s type asteroids as a class are predominantly the core fragments of disrupted differentiated planetesimals a main belt source of the ordinary chondrites remains elusive