diviner lunar radiometer observations of cold traps in the moon s south polar region diviner lunar radiometer experiment surface temperature maps reveal the existence of widespread surface and near surface cryogenic regions that extend beyond the boundaries of persistent shadow the lunar crater observation and sensing satellite lcross struck one of the coldest of these regions where subsurface temperatures are estimated to be 38 kelvin large areas of the lunar polar regions are currently cold enough to cold trap water ice as well as a range of both more volatile and less volatile species the diverse mixture of water and high volatility compounds detected in the lcross ejecta plume is strong evidence for the impact delivery and cold trapping of volatiles derived from primitive outer solar system bodies

global spatial deconvolution of lunar prospector th abundances 1 we have completed the first global spatial deconvolution analysis of planetary gamma ray data for lunar th abundances as measured by the lunar prospector gamma ray spectrometer we tested two different spatial deconvolution techniques jansson s method and the pixon method and determined that the pixon method provides superior performance the final deconvolved map results in a spatial resolution improvement of a factor of 1 5 2 the newly deconvolved data allow us to clearly delineate nearside th enhancements and depressions validate enhanced th abundances associated with specific lunar red spots and reveal new details of the th distribution at the aristarchus plateau

suppression of eddy diffusivity across jets in the southern ocean abstract geostrophic eddies control the meridional mixing of heat carbon and other climatically important tracers in the southern ocean the rate of eddy mixing is typically quantified through an eddy diffusivity there is an ongoing debate as to whether eddy mixing in enhanced in the core of the antarctic circumpolar current or on its flanks a simple expression is derived that predicts the rate of eddy mixing that is the eddy diffusivity as a function of eddy and mean current statistics this novel expression predicts suppression of the cross jet eddy diffusivity in the core of the antarctic circumpolar current despite enhanced values of eddy kinetic energy the expression is qualitatively and quantitatively validated by independent estimates of eddy mixing from altimetry observations this work suggests that the meridional eddy diffusivity across the antarctic circumpolar current is weaker than presently assumed because of the suppression of eddy mixing by the strong zonal current

high spatial resolution studies of epithermal neutron emission from the lunar poles constraints on hydrogen mobility 1 the data from the collimated sensors of the lend instrument are shown to be of exceptionally high quality counting uncertainties are about 0 3 relative and are shown to be the only significant source of random error thus conclusions based on small differences in count rates are valid by comparison with the topography of shoemaker crater the spatial resolution of the instrument is shown to be consistent with the design value of 5 km for the radius of the circle over which half the counts from the lunar surface would be determined the observed epithermal neutron suppression factor due to the hydrogen deposit in shoemaker crater of 0 25 0 04 cps is consistent with the collimated field of view rate of 1 7 cps estimated by mitrofanov et al 2010a the statistical significance of the neutron suppressed regions nsrs relative to the larger surrounding polar region is demonstrated and it is shown that they are not closely related to the permanently shadowed regions there is a significant increase in h content in the polar regions independent of the h content of the nsrs the non nsr h content increases directly with latitude and the rate of increase is virtually identical at both poles there is little or no increase with latitude outside the polar region various mechanisms to explain this steep increase in the non nsr polar h with latitude are investigated and it is suggested that thermal volatilization is responsible for the increase because it is minimized at the low surface temperatures close to the poles

models of the distribution and abundance of hydrogen at the lunar south pole 1 permanently shadowed locations at the lunar poles are potential sites for significant concentrations of cold trapped volatiles including water ice hydrogen enhancements are seen at the poles but the physical form abundance and distribution of this hydrogen remains controversial using a pixon based image reconstruction algorithm to effectively improve spatial resolution we derive maps of the lunar south polar water equivalent hydrogen concentration that are fully consistent with the orbital neutron measurements with abundances greater than 0 5 wt in some permanently shadowed locations this is much greater than the highest solar wind hydrogen abundance in returned lunar samples and may indicate ice between regolith grains if the hydrogen distribution is inhomogeneous within a permanently shadowed crater then even higher abundances are implied in shackleton crater for example the derived count rates are consistent with 10 of the crater floor area having 20 wt water equivalent hydrogen and the remainder at 0 25 wt

major lunar crustal terranes surface expressions and crust mantle origins in light of global remotely sensed data the igneous crust of the moon can no longer be viewed as a simple globally stratified cumulus structure composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual melt kreep sandwich horizon near the base of the lower crust instead global geochemical information derived from clementine multispectral data and lunar prospector gamma ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique 1 the procellarum kreep terrane pkt 2 the feldspathic high lands terrane fht and 3 the south pole aitken terrane spat the pkt is a mafic province coincident with the largely resurfaced area in the procellarum imbrium region whose petrogenesis relates to the early differentiation of the moon here some 40 of the th in the moon s crust is concentrated into a region that constitutes only about 10 of the crustal volume this concentration of th average 5 ppm and by implication the other heat producing elements u and k led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust lower crustal materials within the pkt likely interacted with underlying mantle materials to produce hybrid magmatism leading to the magnesian suite of lunar rocks and possibly kreep basalt although rare in the apollo sample collection widespread mare volcanic rocks having substantial th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources the fht is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation basin impacts into this region do not excavate significantly more mafic material suggesting a thickness of tens of kilometers of anorthositic crust the feldspathic lunar meteorites may represent samples from the anorthositic central region of the fht ejecta from deep penetrating basin impacts outside of the central anorthositic region however indicate an increasingly mafic composition with depth the spat a mafic anomaly of great magnitude may include material of the upper mantle as well as lower crust thus it is designated a separate terrane whether the spa basin impact simply uncovered lower crust such as we infer for the fht remains to be determined

spectral and photogeologic mapping of schrodinger basin and implications for post south pole aitken impact deep subsurface stratigraphy abstract schrodinger basin provides a window into the stratigraphy of the lunar crust adjacent to the south pole aitken basin region that we have probed with lunar reconnaissance orbiter moon mineralogy mapper m 3 and crater scaling relationships the composition of materials that make up the basin wall impact melt and peak ring provide a cross section of the lunar crust which reveals products of the lunar magma ocean subsequent magmatism and reworking of those components into a megaregolith large hectometer to kilometer size areas of anorthite rich material anorthosite low ca pyroxene material a noritic unit and olivine rich material troctolite or dunite are exposed with a few areas of intermediate composition the schrodinger impact excavated 20 km into an orthopyroxene plagioclase noritic lunar crust which is exposed in the basin walls rim and proximal ejecta and dominates the composition of materials that make up the basin floor substantially later in lunar history two spatially and chronologically isolated volcanic eruptions occurred on the basin floor two large craters east of schrodinger excavated a compositionally gabbroic subsurface unit that was not tapped by schrodinger this indicates a compositional crustal facies change which may be from spa ejecta but could reflect heterogeneity in the original lunar crust

topographic forcing of the atmosphere and a rapid change in the length of day during june to september 1992 a special campaign was held to measure rapid changes in earth s rotation rate and to relate these measurements to variations in the atmosphere s angular momentum due principally to changes in zonal winds a strong rise in both length of day and atmospheric momentum during a particular 6 day subperiod is documented and this example of a short period perturbation is identified with a specific regional coupling mechanism mountain torques within the southern tropics appear to account for most of the rapid momentum transfer between the solid earth and atmosphere with those across south america especially important

evidence for explosive silicic volcanism on the moon from the extended distribution of thorium near the compton belkovich volcanic complex we reconstruct the abundance of thorium near the compton belkovich volcanic complex on the moon using data from the lunar prospector gamma ray spectrometer we enhance the resolution via a pixon image reconstruction technique and find that the thorium is distributed over a larger 40km 75 km area than the 25km 35 km high albedo region normally associated with compton belkovich our reconstructions show that inside this region the thorium concentration is 14 26ppm we also find additional thorium spread up to 300km eastward of the complex at 2 ppm the thorium must have been deposited during the formation of the volcanic complex because subsequent lateral transport mechanisms such as small impacts are unable to move sufficient material the morphology of the feature is consistent with pyroclastic dispersal and we conclude that the present distribution of thorium was likely created by the explosive eruption of silicic magma

lunar surface rock abundance and regolith fines temperatures derived from lro diviner radiometer data 1 surface temperatures derived from thermal infrared measurements provide a means of understanding the physical properties of the lunar surface the contrasting thermophysical properties between rocks and regolith fines cause multiple temperatures to be present within the field of view of nighttime multispectral data returned from the lunar reconnaissance orbiter lro diviner radiometer between 60 n s latitudes regolith temperatures are influenced by the presence of rocks in addition to factors such as the thermophysical properties of the regolith fines latitude and local slopes and radiative heating from adjacent crater walls preliminary comparisons of derived rock concentrations with lro camera images show both qualitative and quantitative agreement although comparisons of derived rock concentrations with circular polarization ratio radar data sets display general similarities there are clear differences between the two data sets in the relative magnitude and areal extent of rocky signatures several surface units can be distinguished based on their regolith temperature and rock concentration values and distributions including maria and highlands surfaces rocky impact craters rilles and wrinkle ridges dark mantled deposits and isolated cold surfaces rock concentrations are correlated with crater age and rocks are only preserved on the youngest surfaces or where steep slopes occur and mass wasting prevents mantling with fines the presence of rocky surfaces excavated by young impacts allows for the estimation of minimum regolith thickness from the size of the impact the derived rock concentrations confirm the presence of thicker regolith cover in the highlands and in locations of radar dark haloes

thorium abundances on the aristarchus plateau insights into the composition of the aristarchus pyroclastic glass deposits 1 thorium th data from the lunar prospector gamma ray spectrometer lp grs are used to constrain the composition of lunar pyroclastic glass deposits on top of the aristarchus plateau our goal is to use forward modeling of lp grs th data to measure the th abundances on the plateau and then to determine if the elevated th abundances on the plateau are associated with the pyroclastic deposits or with thorium rich ejecta from aristarchus crater we use a variety of remote sensing data to show that there is a large homogenous portion of the pyroclastics on the plateau that has seen little or no contamination from the th rich ejecta of aristarchus crater our results show that the uncontaminated pyroclastic glasses on aristarchus plateau have an average th content of 6 7 ppm and 7 wt tio2 these th and ti values are consistent with th rich intermediate ti yellow glasses from the lunar sample suite on the basis of this information we use petrologic equations and interelement correlations for the moon to estimate the composition of the source region from which the aristarchus glasses were derived we find that the source region for the aristarchus glasses contained high abundances of heat producing elements which most likely served as a thermal driver for the prolonged volcanic activity in this region of the moon

detection of the earth rotation response to a rapid fluctuation of southern ocean circulation in november 2009 1 at seasonal and shorter periods the solid earth and its overlying geophysical fluids form a closed dynamical system which except for tidal forcing conserves its total angular momentum while atmospheric effects dominate changes in the earth s rate of rotation and hence length of day lod on these time scales the addition of oceanic angular momentum oam estimates has been shown to improve closure of the lod budget in a statistical sense here we demonstrate for the first time the signature of a specific sub monthly ocean current fluctuation on the earth s rotation rate coinciding with recently reported anomalies which developed in southeast pacific surface temperature and bottom pressure fields during late 2009 our results show that concurrent variations in the antarctic circumpolar current acc which saw a sharp drop and recovery in zonal transport during a two week period in november were strong enough to cause a detectable change in lod following the removal of atmospheric angular momentum aam computed from the modern era retrospective analysis for research and applications merra database the strong oam variations driving the lod aam changes were diagnosed from ocean state estimates of the consortium for estimating the circulation and climate of the ocean ecco and involved roughly equal contributions from the current and pressure terms with in situ confirmation for the latter provided by tide corrected bottom pressure recorder data from the south drake passage site of the antarctic circumpolar current levels by altimetry and island measurements acclaim network

testing polar spots of water rich permafrost on the moon lend observations onboard lro 1 results are presented for the lend instrument onboard lro for the detection of local spots of suppression and excess of epithermal neutron emission at the lunar poles twelve local neutron suppression regions nsrs and neutron excess regions ners are detected it is shown using the data from the lola and diviner instruments that six nsrs have the empirical property less local irradiation and lower temperature fewer local neutrons these nsrs may be identified with spots of water ice rich permafrost on the moon it is shown that detected nsrs are include in both permanently shadowed and illuminated areas and they are not coincident with permanently shadowed regions psrs at the bottom of polar craters as has been commonly expected before lend presented neutron data with high spatial resolution

the miniature radio frequency instrument s mini rf global observations of earth s moon abstract radar provides a unique means to analyze the surface and subsurface physical properties of geologic deposits including their wavelength scale roughness the relative depth of the deposits and some limited compositional information the nasa lunar reconnaissance orbiter s lro miniature radio frequency mini rf instrument has enabled these analyses on the moon at a global scale mini rf has accumulated 67 coverage of the lunar surface in s band 12 6 cm radar with a resolution of 30 m pixel here we present new mini rf global orthorectified uncontrolled s band maps of the moon and use them for analysis of lunar surface physical properties reported here are readily apparent global and regional scale differences in lunar surface physical properties that suggest three distinct terranes namely a 1 nearside radar dark region 2 orientale basin and continuous ejecta and the 3 highlands radar bright region integrating these observations with new data from lro s diviner radiometer rock abundance maps as well clementine and lunar prospector derived compositional values show multiple distinct lunar surface terranes and sub terranes based upon both physical and compositional surface properties previous geochemical investigations of the moon suggested its crust is best divided into three to four basic crustal provinces or terranes feldspathic highlands terrane an and outer procellarum kreep terrane and south pole aitken terrane that are distinct from one another however integration of these geochemical data sets with new geophysical data sets allows us to refine these terranes the result shows a more complex view of these same crustal provinces and provides valuable scientific and hazard perspectives for future targeted human and robotic exploration

antarctic circumpolar current transport variability during 2003 05 from grace abstract gravity recovery and climate experiment grace gravity data spanning january 2003 november 2005 are used as proxies for ocean bottom pressure bp averaged over 1 month spherical gaussian caps 500 km in radius and along paths bracketing the antarctic circumpolar current s various fronts the grace bp signals are compared with those derived from the estimating the circulation and climate of the ocean ecco ocean modeling assimilation system and to a non boussinesq version of the regional ocean model system roms the discrepancy found between grace and the models is 1 7 cmh2o 1 cmh2o 1 hpa slightly lower than the 1 9 cmh2o estimated by the authors independently from propagation of grace errors the northern signals are weak and uncorrelated among basins the southern signals are strong with a common seasonality the seasonal cycle grace data observed in the pacific and indian ocean sectors of the acc are consistent with annual and semiannual amplitudes of 3 6 and 0 6 cmh2o 1 1 and 0

driven by excess climatic implications of new global mapping of near surface water equivalent hydrogen on mars abstract we present improved mars odyssey neutron spectrometer mons maps of near surface water equivalent hydrogen weh on mars that have intriguing implications for the global distribution of excess ice which occurs when the mass fraction of water ice exceeds the threshold amount needed to saturate the pore volume in normal soils we have refined the crossover technique of feldman et al 2011 by using spatial deconvolution and gaussian weighting to create the first globally self consistent map of weh at low latitudes our new maps indicate that weh exceeds 15 in several near equatorial regions such as arabia terra which has important implications for the types of hydrated minerals present at low latitudes at high latitudes we demonstrate that the disparate mons and phoenix robotic arm ra observations of near surface weh can be reconciled by a three layer model incorporating dry soil over fully saturated pore ice over pure excess ice such a three layer model can also potentially explain the strong anticorrelation of subsurface ice content and ice table depth observed at high latitudes at moderate latitudes we show that the distribution of recently formed impact craters is also consistent with our latest mons results as both the shallowest ice exposing crater and deepest non ice exposing crater at each impact site are in good agreement with our predictions of near surface weh overall we find that our new mapping is consistent with the widespread presence at mid to high martian latitudes of recently deposited shallow excess ice reservoirs that are not yet in equilibrium with the atmosphere

radar imaging of the lunar poles long wavelength measurements reveal a paucity of ice in the moon s polar craters we have used a radio telescope at arecibo observatory puerto rico to map features of the lunar poles some as small as 300 metres across by collecting long wavelength radar images that can penetrate several metres of lunar dust we find that areas of the crater floors at the poles that are in permanent shadow from the sun which are potential cold traps for water or other volatiles do not give rise to strong radar echoes like those associated with thick ice deposits in the polar craters on mercury any lunar ice present within regions visible to the arecibo radar must therefore be in the form of distributed grains or thin layers

the global albedo of the moon at 1064 nm from lola the lunar orbiter laser altimeter lola measures the backscattered energy of the returning altimetric laser pulse at its wavelength of 1064 nm and these data are used to map the reflectivity of the moon at zero phase angle with a photometrically uniform data set global maps have been produced at 4 pixels per degree about 8 km at the equator and 2 km resolution within 20 latitude of each pole the zero phase geometry is insensitive to lunar topography so these data enable characterization of subtle variations in lunar albedo even at high latitudes where such measurements are not possible with the sun as the illumination source the geometric albedo of the moon at 1064 nm was estimated from these data with absolute calibration derived from the kaguya multiband imager and extrapolated to visual wavelengths the lola estimates are within 2 of historical measurements of geometric albedo no consistent latitude dependent variations in reflectance are observed suggesting that solar wind does not dominate space weathering processes that modify lunar reflectance the average normal albedo of the moon is found to be much higher than that of mercury consistent with prior measurements but the normal albedo of the lunar maria is similar to that of mercury suggesting a similar abundance of space weathering products regions within permanent shadow in the polar regions are found to be more reflective than polar surfaces that are sometimes illuminated limiting analysis to data with slopes less than 10 eliminates variations in reflectance due to mass wasting and shows a similar increased reflectivity within permanent polar shadow steep slopes within permanent shadow are also more reflective than similar slopes that experience at least some illumination water frost and a reduction in effectiveness of space weathering are offered as possible explanations for the increased reflectivity of permanent shadow porosity is largely ruled out as the sole explanation the south polar crater shackleton is found to be among the most reflective craters in its size range globally but is not the most reflective so mass wasting cannot be ruled out as a cause for the crater s anomalous reflectance models of the abundance of ice needed to account for the reflectance anomaly range from 3 to 14 by weight or area depending on assumptions regarding the effects of porosity on reflectance and whether ice is present as patches or is well mixed in the regolith if differences in nanophase iron abundances are responsible for the anomaly the permanently shadowed regions have between 50 and 80 the abundance of nanophase iron in mature lunar soil

spatial distribution of lunar polar hydrogen deposits after kaguya selene 1 although controversial in its physical form there is mounting evidence of hydrogen enhancements at the lunar poles the permanently shadowed locales are potential sites for significant concentrations of cold trapped volatiles including water ice we derive maps of the lunar hydrogen distribution near the poles by applying a pixon image reconstruction algorithm to the lunar prospector epithermal neutron data coupled with a new map of cold trap locations derived from the kaguya selene altimetry measurements the results presented in this article require the hydrogen to be concentrated into cold traps

lunar polar topography derived from clementine stereoimages clementine stereoimagery has been used to produce digital elevation models of the moon at a scale of 1 km pixel these models cover regions poleward of 60 in both hemispheres and reveal topography beyond that covered by the clementine laser altimeter or earth based radar by combining these polar terrain models with the current clementine laser altimeter data we have produced a global topographic map of the lunar surface several topographic features in the new polar topographic data set are described including three previously unrecognized pre nectarian impact basins several known basins have also been mapped including the southern extent of the south pole aitken basin and other previously suspected basins have been verified

integration of lunar polar remote sensing data sets evidence for ice at the lunar south pole in order to investigate the feasibility of ice deposits at the lunar south pole we have integrated all relevant lunar polar data sets these include illumination data arecibo ground based monostatic radar data newly processed clementine bistatic radar data and lunar prospector neutron spectrometer measurements the possibility that the lunar poles harbor ice deposits has important implications not only as a natural resource for future human lunar activity but also as a record of inner solar system volatiles e g comets and asteroids over the past billion years or more we find that the epithermal neutron flux anomalies measured by lunar prospector are coincident with permanently shadowed regions at the lunar south pole particularly those associated with shackleton crater furthermore these areas also correlate with the 0 circular polarization ratio cpr enhancements revealed by new processing of clementine bistatic radar echoes which in turn are colocated with areas of anomalous high cpr observed by arecibo observatory on the lower sun shadowed wall of shackleton crater estimates of the extent of high cpr from arecibo observatory and clementine bistatic radar data independently suggest that 10 km2 of ice may be present on the inner earth facing wall of shackleton crater none of the experiments that obtained the data presented here were ideally suited for definitively identifying ice in lunar polar regions by assessing the relative merits of all available data we find that it is plausible that ice does occur in cold traps at the lunar south pole and that future missions with instruments specifically designed to investigate these anomalies are worthy

equatorial locations of water on mars improved resolution maps based on mars odyssey neutron spectrometer data abstract we present a map of the near subsurface hydrogen distribution on mars based on epithermal neutron data from the mars odyssey neutron spectrometer the map s spatial resolution is approximately improved two fold via a new form of the pixon image reconstruction technique we discover hydrogen rich mineralogy far from the poles including 10 wt water equivalent hydrogen weh on the flanks of the tharsis montes and 40 wt weh at the medusae fossae formation mff the high weh abundance at the mff implies the presence of bulk water ice this supports the hypothesis of recent periods of high orbital obliquity during which water ice was stable on the surface we find the young undivided channel system material in southern elysium planitia to be distinct from its surroundings and exceptionally dry there is no evidence of hydration at the location in elysium planitia suggested to contain a buried water ice sea finally we find that the sites of recurring slope lineae rsl do not correlate with subsurface hydration this implies that rsl are not fed by large near subsurface aquifers but are instead the result of either small

earth s variable rotation recent improvements in geodetic data and practical meteorology have advanced research on fluctuations in the earth9s rotation theinterpretation of these fluctuations is inextricably linked with studies of the dynamics of the earth moon system and dynamical processes in the liquid metallic core of the earth where the geomagnetic field originates other parts of the earth9s interior and the hydrosphere and atmosphere fluctuations in the length of the day occurring on decadal time scales have implications for the topography of the core mantle boundary and the electrical magnetic and other properties of the core and lower mantle investigations of more rapid fluctuations bear on meteorological studies of interannual seasonal and intraseasonal variations in the general circulation of the atmosphere and the response of the oceans to such variations

evidence for water ice near the lunar poles improved versions of lunar prospector thermal and epithermal neutron data were studied to help discriminate between potential delivery and retention mechanisms for hydrogen on the moon improved spatial resolution at both poles shows that the largest concentrations of hydrogen overlay regions in permanent shade in the north these regions consist of a heavily cratered terrain containing many small less than 10 km diameter isolated craters these border circular areas of hydrogen abundance h that is only modestly enhanced above the average equatorial value but that falls within large flat bottomed and sunlit polar craters near the south pole h is enhanced within several 30 km scale craters that are in permanent shade but is only modestly enhanced within their sunlit neighbors we show that delivery by the solar wind cannot account for these observations because the diffusivity of hydrogen at the temperatures within both sunlit and permanently shaded craters near both poles is sufficiently low that a solar wind origin cannot explain their differences we conclude that a significant portion of the enhanced hydrogen near both poles is most likely in the form of water molecules

the migration of volatiles on the surfaces of mercury and the moon radar observations of mercury have provided the startling discovery of the probable existence of substantial deposits of ices in permanently shaded polar regions butler et al 1993 harmon et al 1994 this has renewed the old argument about the existence of such deposits in the polar regions of the moon it is most likely necessary for volatiles to be able to migrate to the polar regions of these bodies in order to build up such deposits this paper presents the results of the extension of a monte carlo simulation of the migration of molecules on the surface of mercury by butler et al 1993 the results of the simulations show that for typical conditions on mercury 5 15 of all h 2 o which is placed randomly on the surface migrates to stable permanently shaded polar regions for the moon the numbers are 20 50 the numbers for the migration of co 2 are 2 for mercury and 13 for the moon these percentages are similar to those previously calculated and support the idea of ice deposits in the polar regions of both mercury and the moon

global distribution of lunar composition new results from lunar prospector 1 maps of thorium th feo the ratio of epithermal to thermal neutrons e t and fast neutrons fn from lunar prospector were studied to determine their global distribution on the moon these distributions are compared to that of the 750 nm lunar albedo from clementine to aid in their interpretation all distributions were parameterized using a spherical harmonic expansion out to order l 30 resultant harmonic coefficients generally decrease with increasing l value as a power law in l for all five variables the axes of all dipole components l 1 cluster closely about a centroid given by 14 1 latitude and 16 4 west longitude this location is very close to the symmetry axes of their quadrupole components l 2 which cluster about a centroid given by 24 6 latitude and 25 1 west longitude both centroids are near the center of a suggested procellarum basin given by whitaker 1981 at 23 latitude and 15 west longitude this suggestion is strengthened by a sharp decrease of the intensities of all three variables at 50 from the centroids which is close to the boundary of the putative procellarum basin the coincidence of the global concentration of heat producing elements through th and mare deposits on the lunar surface through feo t e and fn with the circular outline of a putative procellarum basin suggests that the events that were responsible for producing oceanus procellarum perhaps a single giant impact must figure importantly in shaping the global distribution of surface composition a second apparently older circular structure having its center near 5 latitude and 65 east longitude and a radius of 50 is also hinted at in the data

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

the clementine bistatic radar experiment during the clementine 1 mission a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle beta for selected lunar areas observations of the lunar south pole yield a same sense polarization enhancement around beta 0 analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole radar observations of periodically solar illuminated lunar surfaces including the north pole yielded no such enhancement a probable explanation for these differences is the presence of low loss volume scatterers such as water ice in the permanently shadowed region at the south pole

major compositional units of the moon lunar prospector thermal and fast neutrons global maps of thermal and fast neutron fluxes from the moon suggest three end member compositional units a high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks the south pole aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels consistent with more mafic rocks there appears to be a smooth transition between the most mafic and feldspathic compositions which correspond to low and high surface altitudes respectively the maria show low thermal and high fast neutron fluxes consistent with basaltic rocks

fluxes of fast and epithermal neutrons from lunar prospector evidence for water ice at the lunar poles maps of epithermal and fast neutron fluxes measured by lunar prospector were used to search for deposits enriched in hydrogen at both lunar poles depressions in epithermal fluxes were observed close to permanently shaded areas at both poles the peak depression at the north pole is 4 6 percent below the average epithermal flux intensity at lower latitudes and that at the south pole is 3 0 percent below the low latitude average no measurable depression in fast neutrons is seen at either pole these data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles

coherence of antarctic sea levels southern hemisphere annular mode and flow through drake passage 1 it is known from small sets of tide gauges that sub surface pressure sea level corrected for the inverse barometer effect around antarctica varies coherently around about half of the continent and that this coherent signal is related to atmospheric forcing in the form of the antarctic oscillation or southern hemisphere annular mode we here confirm that this coherence extends to a more extensive network of tide gauges and to parts of the continental shelf far from the shore as measured by bottom pressure gauges we use time series from an eddy permitting ocean model with realistic forcing to relate the coherent mode to fluctuations in transport through drake passage and confirm using a 1 resolution barotropic model that the fluctuations are predominantly due to barotropic dynamics although baroclinic dynamics are expected to play an increasing role at interannual timescales

image reconstruction techniques in neutron and gamma ray spectroscopy improving lunar prospector data we present improved resolution maps of the lunar prospector neutron spectrometer thermal epithermal and fast neutron data and gamma ray spectrometer th line fluxes via global application of pixon image reconstruction techniques with the use of mock data sets we show that the pixon image reconstruction method compares favorably with other methods that have been used in planetary neutron and gamma ray spectroscopy the improved thermal neutron maps are able to clearly distinguish variations in composition across the lunar surface including within the lunar basins of hertzsprung and schrodinger the improvement in resolution reveals a correlation between albedo and thermal neutron flux within the basins the consequent increase in dynamic range confirms that hertzsprung basin contains one of the most anorthositic parts of the lunar crust including nearly pure anorthite over a region tens of kilometers in diameter at orientale the reconstructed epithermal neutron data show broad overlap with circular polarization ratio but there remains a mismatch between measures of regolith maturity that sample the surface and those that probe the near subsurface which is consistent with a complex layering scenario

thermal maturation of the lower palaeozoic strata of northern greenland from conodont colour alteration index cai data implications for burial history and hydrocarbon exploration conodont colour alteration data for the lower palaeozoic strata of the north greenland carbonate platform indicate a pattern of increased thermal maturity northwards within the franklinian basin there is little variation in values through the canadian llandovery lower ordovician lower silurian interval at any given locality a simplified thermal model for the platform suggests that the predominant control of conodont colour alteration and thermal maturation was maximum depth of burial which occurred during the mid to late silurian a preliminary integrated scheme for conodont and organic thermal maturity indicators can be compiled from the data now available from north greenland

chemical information content of lunar thermal and epithermal neutrons simulations of equilibrium thermal and epithermal neutron flux spectra for the moon have been studied to determine their chemical information content most of this information resides in a single parameter the ratio of macroscopic absorption to energy loss cross sections although this parameter cannot specify the chemistry of lunar soils uniquely it provides an index that can be used to quantitatively separate anorthositic from mafic chemistries hydrogen abundances can best be derived from measurements of the epithermal neutron flux which is strongly related to its macroscopic energy loss cross section the ratio of thermal to epithermal neutron flux measured by lunar prospector is shown to agree quantitatively with simulations this agreement is used to show that the highlands terrane on the farside of the moon is anorthositic containing high percentages of plagioclase and possibly a range of mg suite minerals with a high mg mg fe atomic ratio our best estimate of the abundance of feo is 2 with an upper limit of 5

the oceanic contribution to the earth s seasonal angular momentum budget seasonal variations in the speed of the earth s rotation manifest themselves as fluctuations in the length of the day lod with an amplitude of about 1000 microseconds s we know from previous work that at least 95 of these variations can be accounted for in terms of angular momentum exchanged between the atmosphere and the solid earth here we examine the respective contributions of the antarctic circumpolar current acc and the global oceans to the earth s seasonal angular momentum budget using in situ data from the drake passage and results from both the oceanic regional model fine resolution antarctic model fram of webb et al 1991 and the global oceanic model of maier reimer et al 1993 as analyzed by brosche et al 1990 the estimated annual contribution of the acc 2 4 s is much smaller than the total variation in the oceanic models or the existing lod aam residual both 15 20 s the estimated semi annual acc contribution 3 8 s is offset by counter currents further north in both oceanic models which exhibit larger semi annual variations in planetary angular momentum further refinements in the earth s seasonal angular momentum budget therefore will require the full planetary plus relative contribution of the global oceans in addition to that of the acc

lunar craters with radar bright ejecta abstract a small fraction of the lunar impact craters with diameters of 1 km and greater have extensive enhanced 3 8 cm radar echoes associated with their ejecta deposits the physical properties of these ejecta deposits and the ages of the central craters have been characterized via various infrared radar and optical signatures most of these ejecta deposits are radar bright at the 3 8 cm wavelength but are not radar bright at the 70 cm wavelength some ejecta have large infrared signatures others do not although most of these ejecta have bright albedos in full moon photographs a significant fraction of the bright albedo markings do not extend beyond the crater this mix of remote sensing signatures indicates that craters with 3 8 cm radar bright halos are young and have ejecta deposits containing an excess of surface or near surface rocks relative to the surrounding terrain abundant centimeter sized rocks are inferred from the high 3 8 cm radar and infrared signatures the low 70 cm radar signatures indicate that larger blocks are much less numerous the population of craters with 3 8 cm radar bright craters on the moon is much smaller than the population of craters in a similar size range on a young mare oceanus procellarum and has a different slope this population is interpreted as a steady state population reflecting a balance between the production of fresh craters and the destruction of the high infrared and radar signatures by small scale cratering the slope of difference between visual and radar craters is attributed to more rapid destruction of the radar signatures in smaller craters relative densities of 3 8 cm radar bright craters and mare craters are estimated to be 0 04 in 0 042 0 016 at a 4 km diameter and 0 100 0 07 0 007 at a 32 km diameter assigning ages on the basis of these relative densities raises the question of whether the 4 to 32 km diameter visual crater population is truly representative of a 3 3 by age if it is and if crater rates between 3 3 by and the present have been uniform than the 3 8 cm radar crater lifetimes are estimated to be 0 13 0 04 0 25 by and 0 03 0 13 0 23 by at diameters of 4 and 32 km respectively similarly lifetimes of the infrared signatures of 4 km diameter craters may be as short as 10 7 years however some data suggest that these estimates may be in error by a factor of 5 too small comminution of blocky ejecta material and the smoothing of slopes by lunar surface processes could account for the elimination of radar signatures on these time scales and the development of a steady state crater population an altenative interpretation which we do not fsvor is that the 3 8 cm radar bright crater population is formed by a subpopulation of primary bodies or by secondary cratering

global elemental maps of the moon the lunar prospector gamma ray spectrometer lunar prospector gamma ray spectrometer spectra along with counting rate maps of thorium potassium and iron delineate large compositional variations over the lunar surface thorium and potassium are highly concentrated in and around the nearside western maria and less so in the south pole aitken basin counting rate maps of iron gamma rays show a surface iron distribution that is in general agreement with other measurements from clementine and the lunar prospector neutron detectors

record warming in the south pacific and western antarctica associated with the strong central pacific el nino in 2009 10 1 satellite data for the past three decades reveal a record high sea surface temperature sst anomaly within a large mid latitude region of the south central pacific scp during the mature phase of the 2009 10 el nino with a peak magnitude that is 5 times the standard deviation of local sst anomaly and is warmer than the concurrent tropical pacific sst anomaly the scp oceanic warming was confined to the upper 50 meters and is associated with an extreme and persistent anticyclone wind changes associated with the anticyclone caused the oceanic warming with surface heat flux and ocean processes playing equally important roles the anticyclone diverted circumpolar westerlies and warm air towards antarctica austral summer sst in the bellingshausen sea also reached a three decade high the extreme atmospheric and oceanic anomalies in the south pacific may have been fueled by the 2009 10 el nino because of its record high sst anomaly in the central equatorial pacific

permanent shadow in simple craters near the lunar poles 1 an analysis of simple craters in the lunar polar regions has produced new values for the minimum amount of permanent shadow in these areas 7500 km2 and 6500 km2 for the north and south pole respectively these values were obtained by conducting illumination simulations of realistically shaped simple craters 20 km in diameter to investigate the size and latitudinal extent of permanently shadowed regions near the lunar poles craters as far as 20 from the pole still contain significant amounts of permanent shadow larger simple craters have slightly more relative permanent shadow than smaller craters seasonal effects are independent of crater size and latitude with a crater having 15 more of its interior shadowed during a lunar day in winter than in summer

lunar fe and ti abundances comparison of lunar prospector and clementine data the lunar prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of clementine spectral reflectance data with the iron and titanium dependence removed the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium incompatible rare earth elements that are enriched in the final phases of magma crystallization these regions are found mainly around the ramparts of the imbrium impact basin but not around the other basins including the much larger and deeper south pole aitken basin this result confirms the compositional uniqueness of the surface and interior of the imbrium region

geochemistry of the lunar highlands as revealed by measurements of thermal neutrons thermal neutron emissions from the lunar surface provide a direct measure of bulk elemental composition that can be used to constrain the chemical properties of near surface depth 85 are generally associated with large impact basins and are colocated with clusters of nearly pure plagioclase identified with spectral reflectance data

analysis of chang e 2 brightness temperature data and production of high spatial resolution microwave maps of the moon abstract the microwave radiation passively emitted from the moon is valuable for investigating the physical properties of the lunar regolith microwave maps which can reveal subsurface characteristics at depths of centimeters to meters give clues to understanding the evolution of the lunar surface china s chang e 2 ce 2 spacecraft carried a microwave radiometer mrm and conducted passive microwave remote sensing of the moon at 3 7 8 19 35 and 37 ghz 10 3 84 1 55 and 0 81 cm wavelengths during 2010 2011 brightness temperature tb data derived from the mrm orbital observations cover the entire moon and the time coverage is over a complete lunation in this paper we use spherical harmonic fits to model the tb variation as functions of local time and latitude using these fits we normalized the day and nighttime tb data measured at various local times into noon time and midnight conditions the spatial sampling of the normalized tb maps is 6 km pixel much higher than ground based observations and higher resolution than the mrm maps derived from chang e 1 by removing the variation in tb related to local time and latitude we produced a series of microwave maps that reveal differences in the properties of the regolith across the lunar surface the microwave behavior of various lunar surface features can be explained primarily by differences in the microwave loss tangent of the materials for example we find that the high ti maria have high daytime tb and exhibit lower nighttime tb than the other maria as a result of the high dielectric loss tangent of ilmenite the ilmenite rich materials are less transparent to microwaves and hence emissions emerge from closer to the surface which is heated strongly in the day and cools quickly at night most fresh craters correspond to low tb spots in the nighttime microwave maps in contrast to their behavior as hot spots in nighttime infrared data suggesting that the higher loss tangent of rocks compared to soils suppresses microwave emission at night the aristarchus plateau has a lower loss tangent relative to its surroundings because it is blanketed by fine grained rock poor pyroclastic material the pyroclastic blanket is more transparent to microwaves than the nearby maria causing the plateau to have relatively cool daytime tb and warm nighttime tb as a consequence of microwave emissions that originate at greater depths the orientale basin is another prominent anomaly in the microwave maps indicating that orientale materials differ in thermophysical and or dielectric properties from typical highland lithologies brightness temperature differences among prominent rayed craters indicate that the very youngest crater rays e g giordano bruno have lower thermal inertia than older but still optically immature rays e g tycho

topography of the lunar poles from radar interferometry a survey of cold trap locations detailed topographic maps of the lunar poles have been obtained by earth based radar interferometry with the 3 5 centimeter wavelength goldstone solar system radar the interferometer provided maps 300 kilometers by 1000 kilometers of both polar regions at 150 meter spatial resolution and 50 meter height resolution using ray tracing these digital elevation models were used to locate regions that are in permanent shadow from solar illumination and may harbor ice deposits estimates of the total extent of shadowed areas poleward of 87 5 degrees latitude are 1030 and 2550 square kilometers for the north and south poles respectively

lunar rare earth element distribution and ramifications for feo and tio2 lunar prospector neutron spectrometer observations lunar prospector neutron spectrometer data have been used to map the global surface distribution of the incompatible rare earth elements gadolinium and samarium from the low altitude 30 15 km mapping orbit these results afford improved surface resolution and detailed views of the potassium rare earth elements and phosphorus kreep distribution within and around mare imbrium and elsewhere the gd and sm results serve as a complementary and independent check of the distribution of kreep on the moon in contrast with the lunar prospector gamma ray spectrometer results for thorium the neutron spectrometer observations reflect the presence of fe and ti as well as gd and sm the contributions of fe and ti are removed using high spatial resolution clementine spectral reflectance determinations of feo and tio2 abundances overall the resulting gd and sm abundance map agrees with the th abundance map determined using the lunar prospector gamma ray spectrometer in general the detailed features of the procellarum imbrium kreep terrane are found in both for example distinct highs in gd sm and th abundances are resolved over the craters mairan aristarchus kepler reinhold lalande and aristillus over the apennine bench and fra mauro regions and over the montes jura and montes carpatus indicating an enhanced abundance of kreep in these locations the neutron observations also provide constraints on feo and tio2 abundances for some high ti locales there is a significant disagreement with tio2 abundances inferred from clementine spectral reflectance

imaging of lunar surface maturity the physical evolution of the lunar surface with exposure to the space environment is termed maturation and maturity is the degree to which a particular lunar soil possesses quantitative characteristics consistent with that exposure several quantitative measures or indices of maturity have been proposed and employed including the abundance of solar wind gas abundance of various types of agglutinates various measures of grain size and is feo among the changes attendant with space exposure are striking changes in the optical characteristics of soils mature lunar soils are dark red and exhibit reduced spectral contrast relative to immature soils this paper presents an optical maturity index that quantifies the spectral effects of maturation we show that this optical maturity index correlates with other maturity indices about as well as the accepted maturity indices correlate among themselves and is only weakly coupled to composition the modest correlations among maturity indices suggest important controls on individual maturity indices other than age uncorrelated variations in the rates of accumulation of individual indicators or variations in depths over which indicators are emplaced in addition to mixing these effects conspire to reduce the equivalence of maturity and duration of surface exposure optical maturity illustrates some of these effects showing that ejecta of large and small craters mature at different rates and that the interiors and ejecta of large craters exhibit systematically different optical maturities the same or analogous effects are likely to influence other maturity indices

rapid ocean signals in polar motion and length of day 1 non tidal variability in ocean currents and bottom pressure is substantial at short periods but relating the associated signals in ocean angular momentum oam to observed polar motion and length of day fluctuations has been difficult our simulations using a barotropic ocean model reveal a clear connection between the estimated oam signals and both polar motion and length of day at periods of 3 10 days the dynamic response of the oceans to barometric pressure plays an important role in the excitation of rapid rotation signals the impact of oam variability is most clear when using gps based earth orientation measurements with little temporal smoothing using the gps series and accounting for oam in addition to atmospheric effects yields substantial improvements in the excitation budget for rapid polar motion and length of day the comparisons with earth rotation data provide a useful check on the rapid ocean variability simulated by the barotropic model

near surface temperatures on mercury and the moon and the stability of polar ice deposits abstract in order to assess the thermal stability of polar ice deposits we present model calculated temperatures of flat surfaces and surfaces within bowl shaped and flat floored polar impact craters on mercury and the moon our model includes appropriate insolation cycles realistic crater shapes multiple scattering of sunlight and infrared radiation and depth and temperature dependent regolith thermophysical properties unshaded water ice deposits on the surface of either body are rapidly lost to thermal sublimation a subsurface water ice deposit is stable within 2 latitude of the moon s poles meter thick water ice deposits require billions of years to sublime if located in the permanently shaded portions of flat floored craters within 10 latitude of the poles of mercury and 13 latitude of the poles of the moon results for craters associated with radar features on mercury are consistent with the presence of stable water ice deposits if a thin regolith layer thermally insulates deposits at lower latitudes and within smaller craters a regolith cover would also reduce losses from diffusion ion sputtering impact vaporization and h ly and is implied independently by the radar observations permanently shaded areas near the moon s poles are generally colder than those near mercury s poles but the moon s obliquity history its orbit through earth s magnetospheric tail and its radar opaque regolith may limit the volume and radar detectability of ice deposits there

small area thorium features on the lunar surface 1 using an improved understanding of the lunar prospector gamma ray spectrometer lp grs spatial footprint we have derived a new map of global thorium abundances on the lunar surface this map has a full width half maximum spatial resolution of 80 km 2 and is mapped on the lunar surface using 0 5 0 5 pixels this map has allowed the identification and classification of 42 small area 3 g g in southwestern mare tranquillitatis near the apollo 11 landing site with our better understanding of the lp grs spatial footprint we have been able to constrain the surface thorium abundance at the compton belkovich thorium anomaly to 40 55 g g which is higher than any other measured location on the lunar surface and higher than most samples finally using 1 km pixel feo abundances from clementine and lp grs spatial footprint information we have been able to obtain plausible thorium distributions around kepler crater at a resolution of 1 km pixel the materials around kepler crater appear to be a relatively simple mixing of thorium rich mib compositions and high thorium mare basalts

thorium abundances on the lunar surface measurements of absolute thorium abundances on the lunar surface are presented using both the high and low altitude data taken with the lunar prospector gamma ray spectrometer an analysis of the uncertainties shows that the measured uncertainties are 7 g g are likely small area regions 150 km 2 using lunar topographic data we have shown that the thorium abundances in the lunar high lands and portions of south pole aitken spa basin are larger for lower elevations we have also studied a number of regions with anomalously high thorium abundances such as the northwestern region of spa basin the crater arago in western tranquillitatis and the compton belkovich region in the northeastern highlands the compton belkovich region appears to be enriched with evolved rocks such as alkali anorthosite and currently represents the only such extended region on the moon that has been identified in contrast tycho crater has very low thorium abundances which suggests that kreep was not assimilated at depth in this portion of the moon

illumination conditions at the lunar south pole recent remote sensing data strongly suggest that deposits of ice occur in permanently shadowed regions at the lunar poles clementine by providing the first contiguous coverage of the moon has enabled the production of an illumination map of the south pole this map shows the extent of the areas of permanent darkness during winter in this region as well as identifying places on the lunar surface that receive illumination for more than 50 of the lunar day the permanently dark areas are prime candidates for locations of ice deposits while regions that are illuminated for anomalous periods are possible sites for lunar bases in this paper we study in detail the illumination history during a lunar day of some of these sites while we find no area that receives permanent illumination we do find two areas only 10 km apart which collectively receive sunlight for over 98 of the time

no evidence for thick deposits of ice at the lunar south pole the rim of the shackleton crater at the lunar south pole is a candidate crash site for nasa s lcross probe lunar crater observation and sensing satellite due to launch in 2008 the plume of debris kicked up by the crash is to be analysed in the hope that it will reveal the water thought to be there suggestions of lunar ice date from 1996 when data from the clementine spacecraft gave some indications of the presence of ice on crater walls at the south pole now using high resolution radar imagery the radar scattering parameter thought indicative of thick ice deposits has been found also to match radar echoes from the rock strewn walls and ejecta of young impact craters at all lunar latitudes there is no evidence for thick ice though there could be grains of water ice spread more thinly through the lunar soil shackleton crater at the moon s south pole has been suggested as a possible site of concentrated deposits of water ice on the basis of modelling of bi static radar polarization properties and interpretations of earlier earth based radar images1 2 this suggestion and parallel assumptions about other topographic cold traps is a significant element in planning for future lunar landings hydrogen enhancements have been identified in the polar regions3 but these data do not identify the host species or its local distribution the earlier earth based radar data lack the resolution and coverage for detailed studies of the relationship between radar scattering properties cold traps in permanently shadowed areas and local terrain features such as the walls and ejecta of small craters here we present new 20 m resolution 13 cm wavelength radar images that show no evidence for concentrated deposits of water ice in shackleton crater or elsewhere at the south pole the polarization properties normally associated with reflections from icy surfaces in the solar system4 5 6 were found at all the observed latitudes and are strongly correlated with the rock strewn walls and ejecta of young craters including the inner wall of shackleton there is no correlation between the polarization properties and the degree of solar illumination if the hydrogen enhancement observed by the lunar prospector orbiter3 indicates the presence of water ice then our data are consistent with the ice being present only as disseminated grains in the lunar regolith

analysis of lunar pyroclastic deposit feo abundances by lro diviner 1 thermal infrared reflectance spectra of rock forming minerals include a prominent minimum near 8 m known as the christiansen feature cf the inflection point wavelength is sensitive to the degree of polymerization of silicates which is strongly influenced by major cations notably iron in the minerals laboratory spectra of lunar soils demonstrate that the cf location is closely correlated to the sample s bulk feo abundance across the full range of apollo soil samples including pyroclastic glass this correlation is the basis for estimating lunar surface feo abundances using orbital thermal infrared measurements the diviner lunar radiometer experiment on the lunar reconnaissance orbiter includes three thermal infrared channels selected to determine the cf positions for sites across the lunar surface diviner measurements are used to derive feo abundances in the aristarchus sulpicius gallus and rima fresnel pyroclastic deposits the calculated feo abundances for aristarchus and sulpicius gallus lie within the compositional range of feo rich pyroclastic glasses but outside the range of most mare soils supporting the interpretations of these deposits as glass rich the calculated feo abundance for the rima fresnel deposit is close to that of mare soils supporting a contention that this deposit is dominated by basaltic fragments rather than glass the diviner measurements hold the potential to determine feo abundances in many lunar pyroclastic deposits a better understanding of these compositions will provide insight into the magmatic history and composition of the lunar interior as well as an enhanced inventory of potential resources for future human exploration

circumpolar structure and distribution of the antarctic circumpolar current fronts 1 mean circumpolar paths 1 high resolution hydrographic sections and maps of the gradient of sea surface height ssh reveal that the antarctic circumpolar current acc consists of multiple jets or frontal filaments here we use a 15 year time series of ssh observations to determine the circumpolar structure and distribution of the acc fronts the jets are consistently aligned with particular streamlines along the entire circumpolar path confirming and extending the results of an earlier study restricted to the region south of australia the intensity of the fronts as measured by the cross front gradient of ssh varies along the fronts and the individual branches merge and diverge often in response to interactions with bathymetry maps of absolute velocity at 1000 m depth derived from argo trajectories confirm the existence of multiple current cores throughout the southern ocean high resolution hydrographic sections and profiles of temperature and salinity from argo floats are used to show that the front locations derived from fitting ssh contours to maps of ssh gradient are consistent with locations inferred from the traditional criteria based on water mass properties suitably modified to account for multiple frontal branches three regions are examined in detail the crozet plateau the kerguelen plateau and the scotia sea these examples show how recognition of the multiple jets of the acc can help resolve discrepancies between previous studies of acc fronts

a record high ocean bottom pressure in the south pacific observed by grace in late 2009 to early 2010 the gravity recovery and climate experiment grace satellite pair observed a record increase in ocean bottom pressure obp over a large mid latitude region of the south east pacific its magnitude is substantially larger than other oceanic events in the southern hemisphere found in the entire grace data records 2003 2010 on multi month time scales the obp data help to understand the nature of a similar signal in sea surface height ssh anomaly observed by altimetry the ssh increase is mainly due to mass convergence analysis of the barotropic vorticity equation using scatterometer data atmospheric reanalysis product and grace and altimeter an atmospheric reanalysis product observations suggests that the observed obp ssh signal was primarily caused by wind stress curl associated with a strong and persistent anticyclone in late 2009 in combination with effects of planetary vorticity gradient bottom topography and friction

global silicate mineralogy of the moon from the diviner lunar radiometer we obtained direct global measurements of the lunar surface using multispectral thermal emission mapping with the lunar reconnaissance orbiter diviner lunar radiometer experiment most lunar terrains have spectral signatures that are consistent with known lunar anorthosite and basalt compositions however the data have also revealed the presence of highly evolved silica rich lunar soils in kilometer scale and larger exposures expanded the compositional range of the anorthosites that dominate the lunar crust and shown that pristine lunar mantle is not exposed at the lunar surface at the kilometer scale together these observations provide compelling evidence that the moon is a complex body that has experienced a diverse set of igneous processes

space weathering effects on lunar cold trap deposits 1 both steady and episodic sources have been proposed as sources of hydrogen observed by lunar prospector in association with the regions of permanent shadow at the poles of the moon either source could supply significant quantities of water to the poles however space weathering processes affect the retention of water in the cold traps we investigate those effects by simulating the evolution of a column of regolith in the region of permanent shadow over time we determine the hydrogen concentration as a function of depth using a monte carlo model of discrete impacts and of delivery from the solar wind we treat the delivery sublimation sputtering and very small scale impacts as continual processes comparing the amount of water delivered to the poles to the amount remaining after space weathering we find a retention efficiency of 5 6 the retention efficiency of the polar cold traps is adequate for preserving volatile deposits over long periods of time the average hydrogen concentration in the regolith column is 4100 ppm in the top meter after 1 gyr this is a saturation level in the regolith increasing the amount of time deepens the enriched layer but does not lead to increased concentrations in 1 gyr about 1 6 m of the regolith is gardened therefore the top meter which is probed by the neutron spectroscopy technique has reached steady state in the simulations the 4100 ppm saturation level is about half of the amount of hydrogen inferred from the lunar prospector neutron data

stability of the west antarctic ice sheet in a warming world equivalent to 0 28 to 0 56 mm yr 1 sea level rise with the rate growing over at least the past two decades 1 4 these observations intensify concerns about the ice sheet s stability that were first raised more than four decades ago 5

polar hydrogen deposits on the moon neutron and gamma ray data measured using the lunar prospector spectrometers were analyzed to define the enhanced hydrogen deposits near both poles of the moon combining the new low altitude neutron data 30 15 km with previous high altitude 100 20 km neutron data and the results of several recent radar investigations sharply constrains the characteristics of each of the polar deposits the deposits at the north appear to be in the form of many small pockets or of generally distributed hydrogen that average to a 100 ppm weight fraction enhancement over that which exists in regolith at more equatorial latitudes those deposits in the permanently shaded craters near the south pole are consistent with a thick ferroan anorthosite regolith containing an enhancement of 1670 890 ppm hydrogen which if in the form of water ice amounts to 1 5 0 8 weight fraction of h sub 2 o neutron data alone cannot discriminate between hydrogen implanted in lunar soil from the solar wind hydrated minerals or h sub 2 o these craters appear to be surrounded by regolith that either contains small pockets of enhanced hydrogen or is soil that is uniformly impregnated with hydrogen enhanced on average by about 100 ppm above that contained in soils at more equatorial latitudes c more 2000 american geophysical union less

a transverse thin skinned thrust fault belt in the paleozoic north greenland fold belt the southern part of the north greenland fold belt in peary land has been affected by two widely different orogenic events an early to middle devonian westward directed thrust fault deformation and a late devonian to an early carboniferous folding on east west axes that folded the earlier thrust faults the deformation in this part of the north greenland fold belt affected an 5 km thick pile of lower paleozoic shales turbidites and conglomerates deposited in the franklinian north greenland clastic trough the thrust fault belt is separated from the northern part of the north greenland fold belt by the east west trending transcurrent harder fjord fault zone north of which no westward directed thrust faults have been recognized the thrust fault region covers an area of 3 000 km 2 and the main transport direction was toward the west with a refraction toward southwest along the sideland to the south the thrust fault region is rimmed by a frontal thrust fault and fold zone behind the frontal zone the uppermost stratigraphical unit the silurian flysch forms an allochthonous mega cover draping imbricate thrust structures in the ordovician units below the central part of the thrust fault belt consists of a western north south striking imbricate thrust fault fan and an eastern and southern area characterized by flat lying coherent thrust sheets the imbricate fan is formed by 20 steeply east dipping thrust sheets with an individual thickness of 500 m the flat lying thrust sheets are 100 300 m thick and the relative displacement along individual thrust faults is in the order of 1 10 km the subhinterland or proximal thrust zone is situated in the eastern part of the thrust fault region and is dominated by the cambrian frigg fjord mudstones this zone is regarded as a peel off area from which the ordovician and silurian sediments were removed and displaced toward the west the frigg fjord mudstones compose the lowermost unit exposed in the region and contain the main decollement zone for the thrust faulting the cumulative effect of the thrusting is a total transport of 100 km from east to west the thrust fault deformation is herein named the volvedal orogeny and is interpreted as a foreland deformation related to the caledonian mobile belt which involved gravity gliding in the hinterland of the thrust fault belt

dating small fresh lunar craters with mini rf radar observations of ejecta blankets 1 the ages of large impact craters on the moon can be estimated by measuring the size frequency distribution of smaller craters superimposed on their ejecta but applying this method to individual craters under 3 km in diameter remains difficult due to their limited areal extent the ejecta blankets of fresh lunar impact craters are expressed as halos of optical and radar bright material that gradually fade with time although compositional differences make inferring crater ages from optical albedo problematic radar is less sensitive to composition and thus may provide a more reliable means of estimating age in this work we use radar data from the miniature radio frequency mini rf instrument on the lunar reconnaissance orbiter lro to characterize the radar backscatter of large numbers of ejecta blankets by analyzing the size frequency distribution of these craters we show that the lifetime of the radar bright discontinuous ejecta blanket varies with crater diameter in a predictable way for craters with diameters between 0 45 and 5 km absolute ages of individual craters can then be estimated by combining this empirically derived model with estimates of the relative degradation state of each individual crater the lifetimes of radar bright discontinuous ejecta blankets are significantly shorter in the highlands than the maria although this is likely due to local topography creating difficulties in applying the method to the highlands the cosmic ray exposure age of south ray crater a fresh crater visited by apollo 16 provides confirmation of these results this method therefore provides a new way to accurately date small fresh craters using the mini rf data set

arecibo radar mapping of the lunar poles a search for ice deposits the arecibo 12 6 centimeter wavelength radar system was used to image the polar regions of the moon at a resolution of 125 meters in a search for ice deposits in areas of possible permanent shadow from the sun no areas greater than 1 square kilometer were found with high radar backscatter cross sections and high circular polarization ratios properties suggestive of the presence of ice a number of areas smaller than 1 square kilometer were found with these properties but optical images from spacecraft missions have shown some of these features to be in sunlight arecibo radar images of sinus iridum at latitude 47 n also showed a number of small features with similar properties the coincidence of some of these features with the radar facing slopes of craters and their presence in sunlit areas suggests that very rough surfaces rather than ice deposits are responsible for their unusual radar properties

iron abundances on the lunar surface as measured by the lunar prospector gamma ray and neutron spectrometers i global measurements of iron abundances on the lunar surface are presented using data from the lunar prospector lp gamma ray spectrometer grs and neutron spectrometer ns in this study we derive relative iron abundances from the low altitude high spatial resolution 45 km 2 lp data using the 7 6 mev neutron capture gamma ray doublet as part of the lp grs analysis we demonstrate the importance of accounting for variations in neutron number density across the lunar surface by measuring neutron fluxes using lp ns data in a first step of comparing the lp grs data with previously published iron abundances inferred from clementine spectral reflectance csr data we show that the existing csr feo data are nonlinear with respect to the lp relative iron abundances we use the lp data to linearize the relationship between the csr and the relative iron values then recalibrate the csr data to iron abundance using returned soil abundances we then correlate the csr data except for major anomalies with the lp relative iron measurements to convert the lp data to absolute iron abundances when we compare the lp grs and revised csr data sets we find a very good correspondence there are two locations mare tranquillitatis and south pole aitken spa basin that show major discrepancies suggesting that the csr data are locally overestimating iron abundances in both these regions the discrepancies identified by the lp grs csr comparison are possibly explained by mineralogical differences that are not accounted for in the csr to feo calibration in regards to our understanding of the moon the lp data have found the following i there exist large expanses of mare basalt in the western mare regions that have very high iron abundances 22 23 wt feo that are underrepresented but not absent from the returned sample collection and are highly unusual for mare soils which typically contain a significant amount of highlands contamination 2 the low iron abundances in the lunar highlands 5 feo wt are consistent with a previous analysis using thermal and epithermal neutrons and with the idea that the lunar crust formed by a relatively simple magma ocean process 3 the comparison of lp and csr derived iron abundances suggests that the material within spa basin is similar to a norite type rock without an enriched mantle feo signature 4 a comparison of lp and csr data at tycho crater shows a large discrepancy such that the csr data show moderate iron abundances of 8 9 wt feo while the lp data show very low iron abundances of 3 4 wt feo this discrepancy cannot yet be easily explained by any known process