an assessment of the importance of chaotic stirring and turbulent mixing on the west florida shelf application of dynamical systems tools has recently revealed in surface ocean currents produced by a hybrid coordinate ocean model hycom simulation the presence of a persistent large scale lagrangian coherent structure lcs on the southern portion of the west florida shelf wfs consistent with satellite tracked drifter trajectories this lcs constitutes a cross shelf barrier for the lateral transport of passive tracers because of the constraints that the above lcs as well as smaller scale lcss lying shoreside can impose on pollutant dispersal and its potentially very important biological consequences a study was carried out on the nature of the surface ocean lagrangian motion on the wfs the analysis is based on the same simulated surface ocean velocity field that has been able to sustain the aforementioned persistent cross shelf transport barrier examination of several diagnostics suggests that chaotic stirring dominates over turbulent mixing on time scales of up to two months or so more specifically it is found on those time scales that tracer evolution at a given length scale is governed to a nonnegligible extent by coarser scale velocity field features fluid particle dispersion is spatially inhomogeneous and the lagrangian evolution is more irregular than the driving eulerian flow

initial observations of lunar impact melts and ejecta flows with the mini rf radar 1 the mini rf radar on the lunar reconnaissance orbiter spacecraft has revealed a great variety of crater ejecta flow and impact melt deposits some of which were not observed in prior radar imaging the craters tycho and glushko have long melt flows that exhibit variations in radar backscatter and circular polarization ratio along the flow comparison with optical imaging reveals that these changes are caused by features commonly seen in terrestrial lava flows such as rafted plates pressure ridges and ponding small 20 km sized craters also show a large variety of deposits including melt flows and ponds two craters have flow features that may be ejecta flows caused by entrained debris flowing across the surface rather than by melted rock the circular polarization ratios cprs of the impact melt flows are typically very high even ponded areas have cpr values between 0 7 and 1 0 this high cpr suggests that deposits that appear smooth in optical imagery may be rough at centimeter and decimeter scales in some places ponds and flows are visible with no easily discernable source crater these melt deposits may have come from oblique impacts that are capable of ejecting melted material farther downrange they may also be associated with older nearby craters that no longer have a radar bright proximal ejecta blanket the observed morphology of the lunar crater flows has implications for similar features observed on venus in particular changes in backscatter along many of the ejecta flows are probably caused by features typical of lava flows

late quaternary vertical slip rates along the southern yadong gulu rift southern tibetan plateau abstract determination of vertical slip rate on different timescales is one of the critical issues along north trending rifts in southern tibet the yadong gulu rift a typical example of these north trending rifts lacked sufficient quantitative data about the vertical slip rate along its southern portion the southern yadong gulu rift is comprised of the relong nieru and the pagri duoqing co grabens which are controlled by a normal fault along its eastern boundary to determine the vertical slip rate we measured the average height of fault scarps along the main fault trace and dated sediments displaced by the scarps by optically stimulated luminescence osl dating the results indicated that the ages of these fault scarps clustered at late pleistocene and the vertical separation of scarps ranged from about 5 5 m to 22 m after abandoning distinctly inaccurate displacements we estimate that the average vertical slip rate of relong graben is 0 7 0 1 mm yr and nieru graben is 0 8 0 1 mm yr while that of pagri duoqing co graben is 2 0 0 5 mm yr since the latest quaternary ca 15 ka by weighting mean slip rate with error it is considered that the different slip rates derive from the dispersed deformation of other faults around the nieru and relong graben and ductile deformation within the lower crust and northern himalaya gneiss dome besides the lack of large earthquakes in historical documents compared with the northern part of yadong gulu rift the inferred pattern of seismic migration and triggering of mht to north trending rifts together indicate that the southern yadong gulu rift is at high risks for middle to large earthquakes m 6 possibly

feo and tio2 concentrations in the south pole aitken basin implications for mantle composition and basin formation we use newly developed spectroscopic methods for determining feo and tio2 abundances to study the huge 2500 km diameter south pole aitken basin the floor of this basin shows iron and titanium values which are weakly correlated and largely range from 7 to 14 wt feo and from 0 5 to 1 5 wt tio2 this composition is consistent with an approximate 1 1 mixture of lower crustal material like that found elsewhere on the moon and mantle rock containing 10 16 wt feo and 0 1 wt tio2 although mantle rock appears to compose about 50 of the floor deposits models of the formation of large impact basins predict that virtually all the floor materials ought to be derived from the mantle

oceanic mesoscale eddies as revealed by lagrangian coherent structures 1 we demonstrate the feasibility of using dynamical systems tools to unambiguously identify mesoscale oceanic eddies from surface ocean currents derived using climatological hydrography and altimetry specifically our analysis is based on extracting lagrangian coherent structures lcss from finite time lyapunov exponent ftle fields the ftle fields reveal with unprecedented detail an intricate tangle of lcss which are hidden in ocean surface topography maps but sometimes are apparent in ocean color images these lcss delineate fluid domains with very different advective properties and thus their detection provides an objective i e frame independent means of identifying eddy boundaries the importance of considering lcss in quantifying transport by eddies is highlighted such a quantification does not rely on the common assumption which is shown to be generally not valid that transport is largely effected by the trapping and subsequent translation of water slugs inside eddies defined as the regions enclosed by sea height streamfunction contours within which rotation dominates over strain lcss are calculated for the whole globe and compared with satellite tracked drogue drifter trajectories within a selected region of the south atlantic

mineralogy of the mafic anomaly in the south pole aitken basin implications for excavation of the lunar mantle the mineralogy of south pole aitken basin spa the largest confirmed impact basin on the moon is evaluated using five color images from clementine although olivine rich material as well as basalts rich in clinopyroxene are readily identified elsewhere on the farside the dominant rock type observed across the interior of spa is of a very noritic composition this mineralogy suggests that lower crust rather than the mantle is the dominant source of the mafic component at spa the lack of variation in observed noritic composition is probably due to basin formation processes during which extensive melting and mixing of target materials are likely to occur

the clementine mission to the moon scientific overview in the course of 71 days in lunar orbit from 19 february to 3 may 1994 the clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths these data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side in addition laser ranging measurements provided the first view of the global topographic figure of the moon the topography of many ancient impact basins has been measured and a global map of the thickness of the lunar crust has been derived from the topography and gravity

scaling impact melting and crater dimensions implications for the lunar cratering record abstract the dimensions of large craters formed by impact are controlled to a large extent by gravity whereas the volume of impact melt created during the same event is essentially independent of gravity this differential scaling fosters size dependent changes in the dynamics of impact crater and basin formation as well as in the final morphologies of the resulting structures a variety of such effects can be observed in the lunar cratering record and some predictions can be made on the basis of calculations of impact melting and crater dimensions among them are the following 1 as event magnitude increases the volume of melt created relative to that of the crater will grow and more will be retained inside the rim of the crater or basin 2 the depth of melting will exceed the depth of excavation at diameters that essentially coincide with both the inflection in the depth diameter trend and the simple to complex transition 3 the volume of melt will exceed that of the transient cavity at a cavity diameter on the order of the diameter of the moon this would arguably correspond to a moon melting event 4 small lunar craters only rarely display exterior flows of impact melt because the relatively small volumes of melt created can become choked with clasts increasing the melt s viscosity and chilling it rapidly larger craters and basins should suffer little from such a process 5 deep melting near the projectile s axis of penetration during larger events will yield a progression in cen tral structure morphology with growing event magnitude this sequence should range from single peaks through multiple peaks to peak rings 6 the minimum depth of origin of central peak material should co incide with the maximum depth of melting the main central peak in a crater the size of tycho should have had a preimpact depth of close to 15 km

spatial variations of stirring in the surface ocean a case study of the tasman sea abstract stirring in the tasman sea is examined using surface geostrophic currents derived from satellite altimeter measurements calculations of the distribution of finite time lyapunov exponents ftles indicate that the stirring in this region is not uniform and stretching rates over 15 days vary from less than 0 02 day 1 to over 0 3 day 1 these variations occur at both small 10 km and large 1000 km scales and in both cases are linked to dynamical features of the flow the small scale variations are related to the characteristics of coherent vortex structures and there are low ftles inside vortices and filaments of high ftles in strain dominated regions surrounding these vortices regional variations in the stirring are closely related to variations in mesoscale activity and eddy kinetic energy eke high values of mean ftle occur in regions of high eke highest mean values of around 0 2 day 1 occur in the east australia current separation region whereas small values occur in regions with low

geology and stratigraphy of king crater lunar farside abstract clementine and photographic data sets have been used to investigate the crustal stratigraphy and geology of king crater on the lunar farside 120 e 5 5 n pre existing topographic regimes or stress fields dominate many structures in the crater which has excavated materials from depths of up to 14 km the upper crust in the area is noritic anorthosite grading to a more anorthositic signature with depth a possible batholithic intrusion is also present in a 15 km wide band extending from the southern crater floor to at least 50 km north of king and from near surface levels down to at least the excavation depth of the crater it is generally feldspathic but is cut by mafic dykes now visible in the north wall king also shows evidence for the presence of a cryptomare exposed in regions of the peaks and in dark halo craters within the ejecta blanket localized olivine bearing mineralogies are observed on the central peaks suggesting isolated pockets of troctolitic mineralogies to have been present at 8 to 14 km depths copious volumes of crystalline melt produced from the impact event cover king s floor to a maximum thickness of 30 60 m and have pooled in a number of natural depressions outside of the main crater the main pool in the pre existing a1 tusi crater has a minimum depth of 150 m domes on the crater floor are verified as nonvolcanic in origin and did not act as a source for any of the lava like materials in king

earth based 12 6 cm wavelength radar mapping of the moon new views of impact melt distribution and mare physical properties abstract we present results of a campaign to map much of the moon s near side using the 12 6 cm radar transmitter at arecibo observatory and receivers at the green bank telescope these data have a single look spatial resolution of about 40 m with final maps averaged to an 80 m four look product to reduce image speckle focused processing is used to obtain this high spatial resolution over the entire region illuminated by the arecibo beam the transmitted signal is circularly polarized and we receive reflections in both senses of circular polarization measurements of receiver thermal noise during periods with no lunar echoes allow well calibrated estimates of the circular polarization ratio cpr and the four element stokes vector radiometric calibration to values of the backscatter coefficient is ongoing radar backscatter data for the moon provide information on regolith dielectric and physical properties with particular sensitivity to ilmenite content and surface or buried rocks with diameter of about one tenth the radar wavelength and larger average 12 6 cm circular polarization ratio cpr values for low to moderate tio 2 mare basalt deposits are similar to those of rough terrestrial lava flows we attribute these high values to abundant few centimeter diameter rocks from small impacts and a significant component of subsurface volume scattering an outflow deposit inferred to be impact melt from glushko crater has cpr values near unity at 12 6 cm and 70 cm wavelengths and thus a very rugged near surface structure at the decimeter to meter scale this deposit does not show radar brightness variations consistent with levees or channels and appears to nearly overtop a massif suggesting very rapid emplacement deposits of similar morphology and or radar brightness are noted for craters such as pythagoras rutherfurd theophilus and aristillus images of the north pole show that despite recording the deposition of orientale material byrd and peary craters do not have dense patterns of radar bright ejecta from small craters on their floors such patterns in amundsen crater near the south pole were interpreted as diagnostic of abundant impact melt so the fraction of orientale derived melt in the north polar smooth plains 1000 km farther from the basin center is inferred to be much lower

regolith composition and structure in the lunar maria results of long wavelength radar studies radar measurements at 70 cm and 7 5 m wavelengths provide insight into the structure and composition of the upper 5 100 m of the lunar regolith and crust we combine high resolution 3 5 km 70 cm radar data for the nearside with earlier calibrated full disk observations at the same wavelength to provide a reasonable estimate of the lunar backscatter coefficient these data are tested against models for echoes from a buried substrate and mie scattering from surface and buried rocks these mechanisms are expected to dominate the 70 cm radar echo with their relative importance determined by the rock population regolith depth substrate roughness and the loss tangent of the soil results indicate that the 70 cm radar echo for the maria comes largely from mie scattering by rocks buried within the fine soil radar scattering from a buried substrate is not likely to greatly affect the observed return we also compared the 70 cm and 7 5 m radar images to infrared eclipse temperature maps crater population age estimates for the maria and to tio2 and feo abundances inferred from earth based telescopic and clementine multispectral observations these data imply that 1 the tio2 ilmenite content of the regolith controls variations in 70 cm depolarized echo strength among mare units with higher titanium abundance leading to lower echoes 2 changes in the average 70 cm return for a given tio2 abundance between maria of different ages do occur but uncertainties in the current radar data do not allow us to uniquely distinguish between variations in rock population with age and calibration effects 3 the 7 5 m radar echoes are controlled by the age of the mare basalt flows with older deposits having a greater degree of fracturing and higher backscatter future mapping at 12 6 cm and 70 cm wavelengths will help to resolve some of the issues raised here

interannual variability of south atlantic circulation from 4 years of topex poseidon satellite altimeter observations variability of large scale and regional south atlantic circulation is investigated using topex poseidon sea level observations interannual variations are identified from empirical orthogonal functions of gridded sea level fields year to year fluctuations of root mean square sea level variability and variability of agulhas eddies evaluated from the along track data two modes of variability are identified a basin scale mode indicates that sea level in the eastern south atlantic underwent a transition from a state of high sea level and enhanced gyre scale geostrophic circulation in 1993 and 1994 to a state of lower sea level and more sluggish circulation in 1996 the dominant mode of basin scale zonal wind has the same temporal signature suggesting a link between the observed variation of gyre scale circulation and the regional wind forcing time variations of this mode also coincide with a transition from a broad agulhas eddy corridor observed in 1993 and 1994 to a narrower corridor observed in 1996 the input of salt and vorticity to the south atlantic subtropical gyre via agulhas eddies may therefore be partially controlled by interannual variations of the wind forced large scale circulation a second mode isolates interannual variations in the brazil malvinas confluence region during 1993 eddy variability along the brazil current extension was relatively strong and variability along the continental slope was weak the opposite pattern was observed in 1995 these variations may be related to interannual variations of the latitude of the confluence while variations associated with both modes are smaller than those observed on seasonal timescales these interannual variations contribute significantly to the total south atlantic variability

possible mantle origin of olivine around lunar impact basins detected by selene the composition structure and evolution of the moon s mantle is poorly constrained a global survey of the moon s surface using the spectral profiler onboard the lunar explorer selene kaguya identifies a number of exposures of olivine in concentric regions around lunar craters with a possible mantle origin

a census of north brazil current rings observed from topex poseidon altimetry 1992 1998 six years of topex poseidon altimeter data are used to investigate the formation of rings and eddies shed by the north brazil current upper layer thickness maps were used to identify 34 of these features formed in the north brazil current retroflection region an average of more than 5 rings and eddies per year the ensemble of ring trajectories closely parallels the 500 m isobath and one out of six rings penetrate into the caribbean sea through the southern lesser antilles the rest of the rings and eddies follow a northern trajectory past barbados once they reach 58w their estimated mean translation speed is 14 km day and their mean length scale is approximately 100 km our results suggest that the formation rate of nbc rings and eddies is nearly twice that previously thought and that they may account for more than 1 3 of the interhemispheric transport within the atlantic meridional overturning cell

the south pole region of the moon as seen by clementine the clementine mission has provided the first comprehensive set of high resolution images of the south pole region of the moon within 5 of latitude of the pole an area of an estimated 30 000 square kilometers remained in shadow during a full lunar rotation and is a promising target for future exploration for ice deposits the schrodinger basin 320 kilometers in diameter centered at 75 s is one of the two youngest least modified great multiring impact basins on the moon a large maar type volcano localized along a graben within the schrodinger basin probably erupted between 1 and 2 billion years ago

zonal jets as transport barriers in planetary atmospheres abstract the connection between transport barriers and potential vorticity pv barriers in pv conserving flows is investigated with a focus on zonal jets in planetary atmospheres a perturbed pv staircase model is used to illustrate important concepts this flow consists of a sequence of narrow eastward and broad westward zonal jets with a staircase pv structure the pv steps are at the latitudes of the cores of the eastward jets numerically simulated solutions to the quasigeostrophic pv conservation equation in a perturbed pv staircase flow are presented these simulations reveal that both eastward and westward zonal jets serve as robust meridional transport barriers the surprise is that westward jets across which the background pv gradient vanishes serve as robust transport barriers a theoretical explanation of the underlying barrier mechanism is provided it is argued that transport barriers near the cores of westward zonal jets across which the background pv gradient is small are found in jupi

moon near infrared spectral reflectance a first good look a positive identification of the minerals olivine plagioclase and several types of pyroxenes were made at several locations on the lunar surface by using remote measurements for example the crater aristarchus is found to have an average pyroxene composition of augite and plagioclase is obviously present a dark mantle deposit in the crater j herschel is at least partly composed of a mixture of 70o7o olivine and 30o7o pyroxene these determinations were possible because the reflectance spectra for 10 20 km diameter lunar areas have been measured for the first time in the ir spectral region 0 65 2 5 m with sufficient spectral resolution and photometric precision to define mineral electronic absorption bands the reflectance for all lunar regions observed over 100 to present continues to increase toward longer wavelengths to at least 2 5 m and several mineral absorption bands appear the telescopic spectra are of similar quality and contain features similar to laboratory spectra of lunar samples the absorption features in several spectra have been quantitatively analyzed using newly developed computer processing techniques including thermal flux removal and absorption band fitting to produce these mineral identifications detection and quantitative analysis of these absorptions provide a much improved basis for remotely determining and mapping surface mineralogy quantitatively from the ground or using airborne or spacecraft platforms

a multispectral geological study of the schrodinger impact basin1 schrodinger basin is a well preserved peak ring basin located on the lunar farside along the rim of the much larger south pole aitken spa basin the relatively young age lower imbrian series

regolith properties in the south polar region of the moon from 70 cm radar polarimetry abstract the south polar region of the moon contains areas permanently shadowed from solar illumination which may provide cold traps for volatiles such as water ice previous radar studies have emphasized the search for diagnostic polarization signatures of thick ice in areas close to the pole but near surface regolith properties and regional geology are also important to upcoming orbital studies of the shadowed terrain to study regional regolith variations we collected 70 cm wavelength 450 m resolution dual circular polarization radar data for latitudes 60 90 s using the arecibo and greenbank telescopes the circular polarization ratio c is sensitive to differences in rock abundance at the surface and up to tens of m below the surface depending upon the regolith loss tangent we observe significant variations in c attributed to changes in the surface and subsurface rock population across the south polar highlands concentric haloes of low polarization ratio surrounding hausen moretus and other young craters represent rock poor ejecta layers values of c up to 1 occur in the floors and near rim deposits of eratosthenian and copernican craters consistent with abundant rocky ejecta and or fractured impact melt enhanced c values also correspond to areas mapped as orientale derived plains forming material wilhelms d e howard k a wilshire h g 1979 usgs map i 1162 and similar polarization properties characterize the permanently shadowed floors of craters faustini and shoemaker small areas of very high 1 5 circular polarization ratio occur on shadowed and seasonally sunlit terrain and appear to be associated with small craters we suggest that regolith in low lying areas near the south pole is characterized by a significant impact melt component from orientale which provides a source for excavation of the block rich ejecta around small craters observed in this and earlier radar studies the lower portion of the interior wall of shackleton crater permanently shadowed from the sun but visible from earth is not significantly different in 70 cm scattering properties from diurnally seasonally sunlit areas of craters with similar morphology

compositional analyses of lunar pyroclastic deposits abstract the 5 band clementine uvvis data at 100 m pixel were used to examine the compositions of 75 large and small lunar pyroclastic deposits lpds and these were compared to representative lunar maria and highlands deposits results show that the albedo spectral color and inferred composition of most lpds are similar to those of low titanium mature lunar maria these lpds may have consisted largely of fragmented basalt with substantial components of iron bearing mafic minerals pyroxenes olivine and smaller amounts if any of volcanic glass several smaller lpds also show substantial highland components three classes of very large deposits can be distinguished from most lpds and from each other on the basis of crystallinity and possible titanium content of their pyroclastic components one class has spectral properties that are dominated by high titanium crystallized black beads e g taurus littrow a second consists of a mixture of high titanium glasses and beads with a higher glass bead ratio sulpicius gallus than that of taurus littrow and a third has a significant component of quenched iron bearing volcanic glasses aristarchus with possible moderate titanium contents although areally extensive these three classes of very large pyroclastic deposits compose only 20 of the 75 deposits studied 27 and eruption of such materials was thus likely to have been less frequent on the moon

impact ejecta emplacement on terrestrial planets abstract impact cratering is one of the most fundamental processes responsible for shaping the surfaces of solid planetary bodies one of the principal characteristics of impact events is the formation and emplacement of ejecta deposits an understanding of which is critical for planetary exploration current models of ejecta emplacement however do not account for several important observations of ejecta deposits on the terrestrial planets in particular the presence of more than one layer of ejecta furthermore there is also no universal model for the origin and emplacement of ejecta on different planetary bodies we present a unifying working hypothesis for the origin and emplacement of ejecta on the terrestrial planets in which the ejecta are emplaced in a multi stage process the generation of the continuous ejecta blanket occurs during the excavation stage of cratering via the conventional ballistic sedimentation and radial flow model this is followed by the emplacement of more melt rich ground hugging flows the surface melt flow phase during the terminal stages of crater excavation and the modification stage of crater formation minor fallback occurs during the final stages of crater formation several factors will affect the final morphology and character of ejecta deposits the volatile content and cohesiveness of the uppermost target rocks will significantly affect the runout distance of the ballistically emplaced continuous ejecta blanket with impact angle also influencing the overall geometry of the deposits e g the production of the characteristic butterfly pattern seen in very oblique impacts ejecta deposited during the surface melt flow stage is influenced by several factors most importantly planetary gravity surface temperature and the physical properties of the target rocks topography and angle of impact play important roles in determining the final distribution of surface melt flow ejecta deposits with respect to the source crater this working hypothesis of ballistic sedimentation and surface melt flow provides a framework in which observations of ejecta at impact craters can be compared and placed in the context of the respective terrestrial planets

a sharper view of impact craters from clementine data the ultraviolet visible camera on the clementine spacecraft obtained high spatial resolution images of the moon in five spectral channels impact craters mapped with these multispectral images show a scale of lithologic diversity that varies with crater size and target stratigraphy prominent lithologic variations feldspathic versus basaltic occur within the south wall of copernicus 93 kilometers in diameter on the scale of 1 to 2 kilometers lithologic diversity at tycho 85 kilometers in diameter is less apparent at this scale although the impact melt of these two large craters is remarkably similar in this spectral range the lunar surface within and around the smaller crater giordano bruno 22 kilometers in diameter is largely dominated by the mixing of freshly excavated material with surrounding older soils derived from a generally similar feldspathic lithology

surface ocean mixing inferred from different multisatellite altimetry measurements abstract two sea surface height ssh anomaly fields distributed by archiving validation and interpretation of satellite oceanographic aviso altimetry are evaluated in terms of the effects that they produce on mixing one ssh anomaly field tagged ref is constructed using measurements made by two satellite altimeters the other ssh anomaly field tagged upd is constructed using measurements made by up to four satellite altimeters advection is supplied by surface geostrophic currents derived from the total ssh fields resulting from the addition of these ssh anomaly fields to a mean ssh field emphasis is placed on the extraction from the currents of lagrangian coherent structures lcss which acting as skeletons for patterns formed by passively advected tracers entirely control mixing the diagnostic tool employed to detect lcss is provided by the computation of finite time lyapunov exponents it is found that currents inferred using upd ssh anomalies support mixing with characteristics similar t

potential sample sites for south pole aitken basin impact melt within the schrodinger basin abstract determining the age of the south pole aitken spa basin ranks among the highest priorities in lunar science this datum would constrain the timing of the oldest and largest basin forming event on the moon information that is essential to any evaluation of the collisional evolution of the early solar system to locate material that preserves the age of spa a geochemical model of spa impact melt is integrated with chemical and mineralogical analyses of the lunar surface determined from orbit results suggest the southern wall of schrodinger basin contains material with the mineralogical and geochemical signatures of spa melt and thus represents a candidate destination for sampling material that can constrain the age of the spa impact

mixing by low and high resolution surface geostrophic currents 1 the nature of mixing near the ocean s surface is investigated by considering passive tracer advection by currents derived geostrophically using sea surface height fields that differ in their spatiotemporal resolution one is a low resolution field that can be thought of as being derived using current generation groundtrack altimetric measurements the other is a high resolution field that may be envisioned as derived using hypothetical next generation wideswath altimetric measurements the investigation is carried out in two world ocean regions with quite distinct characteristics and which have been the focus of recent studies on mixing by altimetry derived currents one region corresponds to an ample domain in the south atlantic which is traversed by vortices shed from the agulhas current the other region corresponds to a portion of the pacific sector of the southern ocean which is dominated by multiple zonal jets associated with the antarctic circumpolar current it is argued that while altimetry derived currents capture the most salient characteristics of surface ocean mixing deterministic lagrangian calculations may be improved by considering surface geostrophic currents with greater spatiotemporal resolution this is supported on analysis of probability distribution functions of finite time lyapunov exponents ftles inspection of lagrangian coherent structures or lcss which constitute distinguished material fluid curves that organize mixing computation of kinetic energy and ftle variance spectra and realization of explicit passive tracer advection experiments

radar remote sensing of pyroclastic deposits in the southern mare serenitatis and mare vaporum regions of the moon 1 we use polarimetric radar observations to study the distribution depth and embedded rock abundance of nearside lunar pyroclastic deposits radar images were obtained for mare vaporum and the southern half of mare serenitatis the imaged areas contain the large rima bode mare vaporum sulpicius gallus and taurus littrow pyroclastic deposits potential pyroclastic deposits at rima hyginus crater the tacquet formation and a dome in mare vaporum are also included data were acquired at s band 12 6 cm wavelength using arecibo observatory and the green bank telescope in a bistatic configuration the s band images have resolutions between 20 and 100 m pixel the pyroclastic deposits appear dark to the radar and have low circular polarization ratios at s band wavelengths because they are smooth easily penetrable by radar waves and generally contain few embedded blocks changes in circular polarization ratio cpr across some of the pyroclastic deposits show areas with increased rock abundance as well as deposits that are shallower radar backscatter and cpr maps are used to identify fine grained mantling deposits in cases where optical and near infrared data are ambiguous about the presence of pyroclastics the tacquet formation in southern serenitatis areas near hyginus crater and a dome in mare vaporum have lower backscatter cross sections than would be expected for mare basalts of similar estimated titanium content combined with very low cpr values this is strong evidence that these areas are covered in fine grained pyroclastic mantling material

global observations of large oceanic eddies 1 ten years of sea surface height ssh fields constructed from the merged topex poseidon t p and ers 1 2 altimeter datasets are analyzed to investigate mesoscale variability in the global ocean the higher resolution of the merged dataset reveals that more than 50 of the variability over much of the world ocean is accounted for by eddies with amplitudes of 5 25 cm and diameters of 100 200 km these eddies propagate nearly due west at approximately the phase speed of nondispersive baroclinic rossby waves with preferences for slight poleward and equatorward deflection of cyclonic and anticyclonic eddies respectively the vast majority of the eddies are found to be nonlinear

rock types of south pole aitken basin and extent of basaltic volcanism the enormous pre nectarian south pole aitken spa basin represents a geophysically and compositionally unique region on the moon we present and analyze the mineralogical diversity across this basin and discuss the implications for basin evolution rock types are derived from clementine multispectral data based on diagnostic characteristics of ferrous absorptions in fresh materials individual areas are characterized as noritic dominated by low ca pyroxene gabbroic basaltic dominated by high ca pyroxene feldspathic 3 6 feo and olivine gabbro dominated by high ca pyroxene and olivine the anorthositic crust has effectively been removed from the interior of the basin the style of volcanism within the basin extends over several 100 myr and includes mare basalt and pyroclastic deposits several areas of ancient pre orientale volcanism or cryptomaria have also been identified the nonmare mafic lithology that occurs across the basin is shown to be noritic in composition and is pervasive laterally and vertically we interpret this to represent impact melt breccia deposits derived from the lower crust a few localized areas are identified within the basin that contain more diverse lithologies gabbro olivine gabbro some of which may represent material from the deepest part of the lower crust and perhaps uppermost mantle involved in the spa event

stirring in the global surface ocean 1 global variations of stirring in the surface ocean are quantified using finite time lyapunov exponents ftles calculated from currents derived from satellite altimetry it is shown that the stirring is highly non uniform and the probability distribution functions pdfs of the ftles are broad asymmetric and have long high stretch tails the characteristics of the pdfs vary with mesoscale activity and integration time there are larger values and broader pdfs in regions of high strain rates and eddy kinetic energy eke e g western boundary currents and the antarctic circumpolar current and for shorter integration times the pdfs have a near universal relationship with the mean strain of a region and are reasonably well fit by weibull distributions the above variations in the stirring may help our understanding of the distribution and spatial heterogeneities of biogeochemical tracers and raise the possibility of developing a parameterization of the stirring based on the easily calculated eke

lunar iron and titanium abundance algorithms based on final processing of clementine ultraviolet visible images the clementine mission to the moon returned global imaging data collected by the ultraviolet visible uvvis camera this data set is now in a final state of calibration and a five band multispectral digital image model dim of the lunar surface will soon be available to the science community we have used observations of the lunar sample return sites and stations extracted from the final dim in conjunction with compositional information for returned lunar soils to revise our previously published algorithms for the spectral determination of the feo and tio2 content of the lunar surface the algorithms successfully normalize the effects of space weathering so that composition may be determined without regard to a surface s state of maturity these algorithms permit anyone with access to the standard archived dim to construct high spatial resolution maps of feo and tio2 abundance such maps will be of great utility in a variety of lunar geologic studies

integrated spectral analysis of mare soils and craters applications to eastern nearside basalts abstract high spatial resolution clementine images are examined to measure the reflectance properties of small and optically immature mare craters that have sampled discrete compositional units the spectral properties of these relatively crystalline mare materials are compared to associated mature soils to determine the effects of space weathering on specific basalt types space weathering is observed to alter the optical properties of distinct lunar basalt units in a systematic manner allowing compositional distinctions to be recognized across maturity states ultraviolet visible reflectance properties of mare basalts are sensitive to titanium content but are relatively independent of maturity state and demonstrate only a slight reddening as regoliths mature to soils other compositional distinctions between basalt types are identified by differences in albedo and band strength of ferrous minerals that are maintained over a full range of maturity states immature deposits within large craters are compared to the spectral properties of well defined mare units to examine the composition of buried materials when craters excavate through the mare highland contamination is readily identified as a mixing relation between mafic and feldspathic lithologies the approach presented here provides new information on the composition and stratigraphy of several nearside mare deposits including the identification of thin low iron and very low titanium basalts in lacus somniorum and more iron rich low titanium basalts in eastern mare frigoris

composition of the lunar highland crust from near infrared spectroscopy near infrared reflectance spectra of the lunar highlands are synthesized to obtain global information about the composition of the lunar near side crust immature exposed surfaces from small fresh craters mountains and massifs and large craters with central peaks are included in a survey of rock types across the lunar near side compositions recognized in these data include anorthosite noritic gabbric and troctolitic mineral assemblages three quarters of the areas studied that represent samples from the upper 1 2 km of lunar crust exhibit noritic compositions with different amounts of pyroxene and or brecciation alteration norites are ubiquitous across the near side and show no spatial clustering associated with any of the major basins in contrast to this noritic megaregolith of the upper crust material representing stratigraphically deeper zones 5 15 km of the lunar crust is dominated by gabbros anorthosites and troctolites with less than a quarter of the areas studied exhibiting a noritic composition the origin of the noritic megaregolith and its relation to deeper crustal material is thus somewhat of an enigma the current limited statistics for areas identified as anorthosites and troctolites are insufficient to derive global spatial distributions gabbroic areas however are notably concentrated in the western hemisphere although incomplete for a global assessment of crustal materials these data demonstrate that the lunar near side crust is clearly mineralogically heterogeneous both laterally and vertically and not well mixed below 1 2 km

origin of the anomalously rocky appearance of tsiolkovskiy crater abstract rock abundance maps derived from the diviner lunar radiometer instrument on the lunar reconnaissance orbiter lro show tsiolkovskiy crater to have high surface rock abundance and relatively low regolith thickness the location of the enhanced rock abundance to the southeast of the crater is consistent with a massive well preserved impact melt deposit apparent in lro miniature radio frequency instrument circular polarization ratio data a new model crater age using lro lunar reconnaissance orbiter camera imagery suggests that while it originated in the late imbrian tsiolkovskiy may be the youngest lunar crater of its size 180 km diameter together these data show that tsiolkovskiy has a unique surface rock population and regolith properties for a crater of its size and age explanation of these observations requires mechanisms that produce more large blocks preserve boulders and large blocks from degradation to regolith and or uncover buried rocks these processes have important implications for formation of regolith on the moon

olivine rich exposures in the south pole aitken basin abstract the distribution and the geological context of the olivine rich exposures in the south pole aitken spa basin on the moon were investigated based on the spectral data obtained from the spectral profiler sp and multiband imager mi onboard the japanese lunar explorer kaguya selene the olivine rich exposures are found only in the peak rings or central peaks of the schrodinger basin and zeeman crater which are located in the outer region of the spa basin and not in the center region on a localized scale the olivine rich materials are exposed on landslide features on the crater walls or sloped wall of the central peaks or the peak rings another observational finding is the co existence of olivine rich and plagioclase rich materials on a kilometer scale spanning most of the olivine rich sites in the schrodinger basin pyroxene rich materials are found in fresh craters outside the peak rings or the central peaks with olivine rich materials based on these results the following scenario are proposed 1 the impact to form the spa basin melted a large amount of the lunar upper mantle and crust and distributed the melted materials to the outer region 2 local differentiation of melted materials hid the olivine rich materials in the center region of the spa basin 3 later impacts that formed the schrodinger and zeeman craters excavated and exposed the olivine rich materials to the surface again and 4 space weathering and regolith gardening obscured the olivine rich spectra at the exposure sites but recent small scale impacts or landslides on the sloped wall exposed fresh olivine rich materials allowing the identification of the olivine rich exposures by spectral remote sensing this suggests that several different scale events play an important role in forming the surface distributions of originally deep seated materials on the moon as well as on other planetary bodies