unsteady vortex behavior in the asian monsoon anticyclone the asian monsoon anticyclone ama which is primarily driven by the latent heat released by monsoon precipitation is one of the dominant features of the northern hemisphere summer circulation in the upper troposphere and lower stratosphere due to variations in the diabatic heating interactions with rossby waves propagating along the subtropical jet and internal dynamics within the anticyclone the circulation of the ama is unsteady here we use the era interim dataset and trajectories computed with era interim winds to show that the ama contains two or three distinct synoptic scale subvortices 69 of the time while a single circulation center is present only 23 of the time more than three simultaneous subvortices are uncommon observed behaviors of the subvortices include 1 splitting of a single vortex into two vortices 2 merger of two vortices into a single vortex 3 vortex shedding in the eastward direction 4 vortex shedding in the westward direction and 5 formation movement and dissipation of a vortex the evolution of the subvortices is closely tied to stirring and transport

what are the sources of mechanical damping in matsuno gill type models the matsuno gill model has been widely used to study the tropical large scale circulations and atmosphere ocean interactions however a common critique of this model is that it requires a strong equivalent linear mechanical damping to get realistic wind response and it is unclear what could provide such a strong damping above the boundary layer this study evaluates the sources and strength of equivalent linear mechanical damping in the walker circulation by calculating the zonal momentum budget using 15 yr 1979 93 of daily global reanalysis data two different reanalyses ncep ncar and 15 yr ecmwf re analysis era 15 give qualitatively similar results for all major terms including the budget residual whose structure is consistent with its interpretation as eddy momentum flux convergence by convective momentum transport cmt the walker circulation is characterized by two distinct regions a deep convection region over the indo pacific warm pool and a shallow convection region over the eastern pacific cold tongue these two regions are separated by a strong upper tropospheric ridge and a strong lower tropospheric trough in the central pacific the resultant pressure gradient forces on both sides require strong approximately 5 10 days damping to balance them because coriolis force near the equator is too small to provide the balance in the deep convection region the damping is provided by cmt and advection together in both the upper and lower troposphere in the shallow convection region on the other hand the damping is provided mainly by advection in the upper troposphere and by cmt in the lower troposphere in other words the upperlevel tropical easterly jet and the low level trade wind are both braked by cmt these results support the use of strong damping in the matsuno gill type models but suggest that the damping rate is spatially inhomogeneous and the cmt related damping increases with the strength of convection implications for gcm s simulation of tropical mean climate are discussed

multispectral studies of western limb and farside maria from galileo earth moon encounter 1 new visible and near infrared multispectral images of the moon obtained by the galileo solid state imaging system along with lunar orbiter images for crater counts and spectral mixing analyses were used to characterize western limb and eastern farside maria and determine compositional and age relationships in selected regions results indicate that 1 western limb mare deposits have less variability in titanium content 6 wt tio2 mare basalts were observed on the western limb and farside which may reflect the inability of such denser magmas to penetrate the thicker farside crust

distribution and modes of occurrence of lunar anorthosite 1 we have utilized telescopic near infrared spectra and multispectral images of the moon provided by the galileo and clementine missions to determine the distribution and modes of occurrence of pure anorthosite anorthosites have now been identified in all portions of the nearside including the site of the putative procellarum basin anorthosite is associated with the rings of orientale grimaldi humorum nectaris nubium mutus vlaq and balmer basins major portions of the inner rings of grimaldi humorum crisium orientale and nectaris are composed of pure anorthosite the large spatial extent of these anorthosites appears to rule out an origin in the upper portions of discrete differentiated mg suite plutons in every instance the anorthosites were exposed from beneath a shallower near surface layer of more pyroxene rich material more mafic material also occurs beneath the pure anorthosite unit large expanses of the northern farside exhibit very low feo values this region contains abundant anorthosite and stands in stark contrast to the mafic composition exhibited by the interior of the south pole aitken basin spa the distribution of compositional units on large portions of the lunar farside as well as the southern portion of the lunar nearside appears to be largely attributable to the spa impact event the distribution and modes of occurrence of anorthosites clearly indicate that a thick global layer of anorthosite is present at various depths beneath most portions of the lunar surface this anorthosite layer dominated the upper portion of the primordial crust and was produced by plagioclase flotation in the global magma ocean

composition of orientale basin deposits and implications for the lunar basin forming process the orientale basin on the lunar western limb has served as the prototype lunar multiring basin for many years in order to constrain possible models of the formation and excavation of basin ejecta we have studied the composition of orientale basin deposits using both earth based spectral reflectance and apollo orbital geochemical data results indicate that orientale basin ejecta are dominantly anorthositic with compositions ranging from pure anorthosite to noritic anorthosite although minor quantities of mare basalt and low k fra mauro basalt are present ultramafic and kreep components appear to be absent portions of the inner rings of the basin may be composed of anorthosite whose shock levels exceed 20 gpa 200 kbar in conjunction with photogeologic evidence for the preservation of prebasin topography and structure within the cordillera basin ring we suggest that the diameter of the excavation crater of the orientale basin is on the order of 500 to 600 km effective depths of excavation are probably less than about half the local crustal thickness which in this region is on the order of 100 km we find that the orientale impact excavated dominantly upper crustal rocks with a depth of excavation consistent with a proportional growth basin forming model

a compositional study of the aristarchus region of the moon using near infrared reflectance spectroscopy newly obtained near infrared reflectance spectra for features on or near the aristarchus plateau demonstrate the diversity of compositions in the region highland units are of three probable compositions a feldspar and clinopyroxene assemblage a probable clinopyroxene olivine and possibly feldspar assemblage and an assemblage composed of olivine or olivine and feldspar the feldspar clinopyroxene assemblage is tentatively correlated with the major th anomaly centered on aristarchus crater the regional pyroclastic deposits on the plateau are composed of greater than 90 fe2 bearing glass the aristarchus cratering event fully penetrated any mare or pyroclastics in the target evidence for mare related material is found in the ejecta on the mare side of the mare plateau contact

practical aspects of avo modeling avo amplitude variation with offset modeling contributes significantly in seismic data acquisition design and prestack seismic data processing and interpretation it has become a common practice in prestack seismic analysis it is also used for verifying and developing avo theories conducting avo modeling is by nature an exercise of multidiscipline integration it thus enhances reservoir characterization and reduces the risk in hydrocarbon exploration

featureless spectra on the moon as evidence of residual lunar primordial crust we report the global distribution of areas exhibiting no absorption features featureless or fl on the lunar surface based on the reflectance spectral data set obtained by the spectral profiler onboard kaguya selene we found that fl sites are located in impact basins and large impact craters in the feldspathic highlands terrane while there are no fl sites in the procellarum regions nor the south pole aitken basin fl sites in each impact basin crater are mainly found at the peak rings or rims where the purest anorthosite pan sites are also found at the local scale most of the fl and pan points are associated with impact craters and peaks most of the fl spectra show a steeper redder continuum than the pan spectra suggesting the occurrence of space weathering effects we propose that most of the material exhibiting a fl spectrum originate from space weathered pan taking into account all the occurrence trends of fl sites on the moon we propose that both the fl and pan materials were excavated from the primordial lunar crust during ancient basin formations below the megaregolith in the highlands since the fl and pan sites are widely distributed over the lunar surface our new data may support the existence of a massive pan layer below the lunar surface

thorium concentrations in the lunar surface iv deconvolution of the mare imbrium aristarchus and adjacent regions the distribution of th over the mare imbrium and northern oceanus procellarum portions of the apollo 15 lunar ground track has been modeled by deconvolving several fields of orbital gamma ray spectroscopy data including a prior study of the apenninus region a continuous swath from 10 e to 60 w in the northwest quadrant has now been analyzed in the aristarchus region the crater dominates the th distribution with a concentration of 20 ppm other enhancements are seen on the aristarchus plateau and south of the plateau the concentration across the aristarchus plateau is not uniform the average th concentration in oceanus procellarum is less to the west than to the east of the aristarchus plateau substantial enhancements are found in mare regions around brayley and at the ejecta blankets of timocharis and lambert th in the eratosthenian mare regions is generally low with one notable exception lying roughly between the craters euler and carlini the existence of enhanced th concentrations in mare basalt regions suggests that reservoirs of some late stage mare basalts incorporated kreep rich material during formation or transit

cyclone and anticyclone formation in a rotating stratified fluid over a sloping bottom we discuss laboratory experiments with a continuous source or sink of fluid in a two layer rotating environment which produces anticyclonic and cyclonic vortices respectively experiments were carried out with a sloping bottom in order to simulate the eect and they were conducted for dierent values for the source sink flow rate q and the coriolis parameter f the rossby number ro of these vortices was small but nite and the flow was expected to be quasi geostrophic the qualitative behaviour of the anticyclonic and cyclonic vortices was generally similar but it depended on the flow rate for low flow rates a single vortex formed at the source and extended to the west at higher flow rates the vortex broke free from the source and moved to the west this vortex was then followed sequentially by other vortices behaving similarly the westward velocity u of these vortices was calculated and compared with the speed us of a linear topographic rossby wave for multiple vortices the westward velocities were greater than us while for a single vortex produced by a low flow rate the velocity was less than us signicant asymmetry between the anticyclonic and cyclonic vortices was observed in the transition zone from single to multiple vortices which implies that ageostrophic eects were still present in the flow

radar probing of planetary regoliths an example from the northern rim of imbrium basin 1 imaging radar measurements at long wavelengths e g 30 cm allow deep up to tens of meters probing of the physical structure and dielectric properties of planetary regoliths we illustrate a potential application for a mars orbital synthetic aperture radar sar using new earth based 70 cm wavelength radar data for the moon the terrae on the northern margin of mare imbrium the montes jura region have diffuse radar backscatter echoes that are 2 4 times weaker at 3 8 cm 70 cm and 7 5 m wavelengths than most other lunar nearside terrae possible geologic explanations are 1 a pyroclastic deposit associated with sinuous rilles in this region 2 buried mare basalt or a zone of mixed highland basaltic debris cryptomaria or 3 layers of ejecta associated with the iridum and plato impacts that have fewer meter sized rocks than typical highlands regolith while radar data at 3 8 cm to 7 5 m wavelengths suggest significant differences between the montes jura region and typical highlands the surface geochemistry and rock abundance inferred from clementine uv vis data and eclipse thermal images are consistent with other lunar terrae there is no evidence for enhanced iron abundance expected for basaltic pyroclastic deposits near the source vents of the sinuous rilles radial to plato the regions of low 70 cm radar return are consistent with overlapping concentric haloes about iridum and plato and do not occur preferentially in topographically low areas as is observed for radar mapped cryptomaria thus we suggest that the extensive radar dark area associated with the montes jura region is due to overlapping rock poor ejecta deposits from iridum and plato craters comparison of the radial extent of low radar return crater haloes with a model for ejecta thickness shows that these rock poor layers are detected by 70 cm radar where they are on the order of 10 m and thicker a sar in orbit about mars could use similar deep probing to reveal the nature of crater and basin related deposits

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

isolated waves and eddies in a shallow water model abstract a shallow water beta channel model was used to carry out numerical experiments with cyclonic and anticyclonic disturbances of various strengths the model is inviscid so fluid elements conserve potential vorticity q when unforced regions of closed q contours correspond to lagrangian material eddies all fluid within a lagrangian eddy travels with the eddy in contrast to regions of closed height contours motion is wavelike for very weak disturbances maximum particle speed u long planetary wave speed the height field disperses like a group of linear rossby waves and tracers have small oscillatory mainly north south displacements with very little scatter when u the planetary q field is sufficiently distorted for small lagrangian eddies to appear very small eddies are simply bodily advected by the linear wave field small eddies are to some extent self propelling they move westward and north cyclone or south anticyclone moving fluid elements towards their rest latit

tropical stationary waves in a nonlinear shallow water model with realistic basic states abstract the nonlinear shallow water equations are used to study the tropical stationary wave response to steady thermal forcing near the equator in earthlike zonally symmetric basic states a thin 200 m fluid layer is superimposed over a large 1500 m zonally symmetric topography distribution that decreases smoothly from the tropics to the poles thus providing the large meridional height gradients required to maintain realistic zonal mean zonal winds without introducing unrealistically large tropical wave speeds a mean meridional circulation is maintained by relaxing the fluid toward its initial global mean depth both hemispherically symmetric equinoctial and hemispherically asymmetric solstitial basic states are considered stationary waves are generated by adding a fixed mass source sink distribution near the equator the presence of westerly zonal mean winds in the subtropics amplifies the steady eddy response to the tropical mass forcing and shifts the rossby gyres poleward and eastward r

mineralogy of the lunar crust results from clementine received 1997 december 5 accepted in revised form 1998 september 15 abstract the central peaks of 109 impact craters across the moon are examined with clementine ultraviolet visible uvvis camera multispectral data the craters range in diameter from 40 to 180 km and are believed to have exhumed material from 5 30 km beneath the surface to form the peaks including both upper and lower crustal rocks depending on whether craters have impacted into highlands or basins representative five color spectra from spectrally and spatially distinct areas within the peaks are classified using spectral parameters including key ratio which is related to mafic mineral abundance and spectral curvature linked to absorption band shape which distinguishes between low and high ca pyroxene and olivine the spectral parameters are correlated to mineralogical abundances related in turn to highland plutonic rock compositions the derived rock compositions for the various central peaks are presented in a global map from these results it is evident that the lunar crust is compositionally diverse both globally and at local 100 m scales found within individual sets of central peaks although the central peaks compositions imply a crust that is generally consistent with previous models of crustal structure they also indicate a more anorthositic crust than generally assumed with a bulk plagioclase content of 8 1 evolving from pure anorthosite near the surface towards more mafic low ca pyroxene rich compositions with depth comparable to anorthositic norite evidence for mafic plutons occurs in both highlands and basins and represent all mafic highland rock types however the lower crust is more compositionally diverse than the highlands with both a greater range of rock types and more diversity within individual sets of central peaks

vp vs relationship and amplitude variation with offset modelling of glauconitic greensand the relationship between vp and vs may be used to predict vs where only vp is known vp vs is also used to identify pore fluids from seismic data and amplitude variation with offset analysis theoretical physical as well as statistical empirical vp vs relationships have been proposed for reservoir characterization when shear wave data are not available in published work the focus is primarily on the vp vs relationship of quartzitic sandstone in order to broaden the picture we present vp vs relationships of greensand composed of quartz and glauconite by using data from the paleocene greensand nini oil field in the north sea a vp vs relationship derived from modelling is compared with empirical vp vs regressions from laboratory data as well as from log data the accuracy of vs prediction is quantified in terms of root mean square error we find that the vp vs relationship derived from modelling works well for greensand shear wave velocity prediction we model the seismic response of glauconitic greensand by using laboratory data from the nini field our studies here reveal that brine saturated glauconitic greensand can have a similar seismic response to that from oil saturated quartzitic sandstone and that oil saturated strongly cemented greensand can have a similar amplitude variation with offset response to that from brine saturated weakly cemented greensand

origin of olivine at copernicus the central peaks of copernicus are among the few lunar areas where near infrared telescopic reflectance spectra indicate extensive exposures of olivine other parts of copernicus crater and ejecta which were derived from highland units in the upper parts of the target site contain only low ca pyroxene as a mafic mineral the exposure of compositionally distinct layers including the presence of extensive olivine may result from penetration to an anomalously deep layer of the crust or to the lunar mantle we suggest that the procellarum basin and the younger superposed insularum basin have provided access to these normally deep seated crustal or mantle materials by thinning the upper crustal material early in lunar history the occurrences of olivine in portions of the compositionally heterogeneous aristarchus region in a related geologic setting may be due to the same sequence of early events

widespread weathered glass on the surface of mars low albedo sediments cover 10 7 km 2 in the northern lowlands of mars but the composition and origin of these widespread deposits have remained ambiguous despite many previous investigations here we use near infrared spectra acquired by the mars express omega observatoire pour la mineralogie l9eau les glaces et l9activite imaging spectrometer to show that these sediments exhibit spectral characteristics that are consistent with both high abundances of iron bearing glass and silica enriched leached rinds on glass this interpretation is supported by observations of low albedo soil grains with possible rinds at the phoenix mars lander landing site in the northern lowlands by comparison with the extensive glass rich dune fields and sand sheets of iceland we propose an explosive volcanic origin for these glass rich sediments we also propose that the glassy remnant rinds on the sediments are the result of postdepositional alteration as these rinds are commonly formed in arid terrestrial volcanic environments during water limited moderately acidic leaching these weathered glass rich deposits in the northern lowlands are also colocated with the strongest concentrations of a major global compositional surface type previously identified in mid infrared spectra suggesting that they may be representative of global processes our results provide potential confirmation of models suggesting that explosive volcanism has been widespread on mars and also raise the possibilities that glass rich volcaniclastics are a major source of eolian sand on mars and that widespread surficial aqueous alteration has occurred under amazonian climatic conditions

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

spatio temporal stability analysis applied to monsoon anticyclone flow flow on a beta plane driven by a steady localised anticyclonic forcing of potential vorticity or equivalently a mass source is considered as a simple model of the asian monsoon flow in the upper troposphere previous authors have noted that the response may be steady or unsteady according to the magnitude of the forcing with the unsteadiness manifested as westward eddy shedding a detailed study of the transition between steady and eddy shedding regimes reveals a third regime break up for intermediate forcing magnitude where the flow is steady in the neighbourhood of the forcing but the westward extending plume of low potential vorticity breaks up into isolated anticyclonic vortices some distance away from the forcing region a related spatio temporal instability problem for flow on a beta plane is specified and analysed the flow can be stable convectively unstable or absolutely unstable it is argued that these three stability regimes correspond to the steady break up and eddy shedding regimes for the forced flow and good quantitative correspondence between the regimes is demonstrated by explicit solution of the spatio temporal stability problem

the compositional and physical properties of localized lunar pyroclastic deposits abstract lunar localized pyroclastic deposits are low albedo deposits with areas 2 these deposits were difficult to study before the turn of the millennium because of the lack of available high spatial resolution data with the launch of the lunar reconnaissance orbiter kaguya and chaandrayan 1 new sets of diverse high spatial resolution data are now available using several of these data sets we conducted a study of 34 localized pyroclastic deposits globally for each localized pyroclastic deposit we examined topography to estimate pyroclastic volume and juvenile proportions s band radar backscatter thermal infrared derived measures of surficial rock abundance and regolith density and mineral abundances our goals are to 1 quantitatively characterize the physical and mineralogical properties of each localized pyroclastic deposit 2 investigate the physical and mineralogical variations among localized pyroclastic deposits 3 compare these properties of localized 2 to regional pyroclastic deposits 2500 km 2 and 4 provide useful parameters for future volcanological modeling from this study we find that 1 localized pyroclastic deposits exhibit low relief structures 2 the surface rock abundance and circular polarization ratio of localized pyroclastic deposits display a wide range of values 0 2 0 5 and 0 3 0 6 respectively 3 the glass abundance of localized pyroclastic deposits vary between 0 and 80 wt 4 there are four types of localized pyroclastic deposits based upon the surface rock abundance and glass abundance parameters 5 pyroclastic deposits within the same floor fractured crater tend to have similar properties and 6 localized pyroclastic deposits are diverse with respect to regional pyroclastic deposits but a subset of localized pyroclastic deposits have similar physical and mineralogical properties to regional pyroclastic deposits

global assessment of pure crystalline plagioclase across the moon and implications for the evolution of the primary crust recent advancements in visible to near infrared orbital measurements of the lunar surface have allowed the character and extent of the primary anorthositic crust to be studied at unprecedented spatial and spectral resolutions here we assess the lunar primary anorthositic crust in global context using a spectral parameter tool for moon mineralogy mapper data to identify and map fe bearing crystalline plagioclase based on its diagnostic 1 25 m absorption band this allows plagioclase dominated rocks specifically anorthosites to be unambiguously identified as well as distinguished from lithologies with minor to trace amounts of mafic minerals low spatial resolution global mosaics and high spatial resolution individual data strips covering more than 650 targeted craters were analyzed to identify and map the mineralogy of spectrally pure regions as small as 400 m in size spectrally pure plagioclase is identified in approximately 450 targets located across the lunar surface diviner thermal infrared tir data are analyzed for 37 of these nearly monomineralic regions in order to understand the compositional variability of plagioclase an in these areas the average an for each spectrally pure region is estimated using new laboratory measurements of a well characterized anorthite an96 sample diviner tir results suggest that the plagioclase composition across the lunar highlands is relatively uniform high in calcium content and consistent with plagioclase compositions found in the ferroan anorthosites an94 98 our results confirm that spectrally pure anorthosite is widely distributed across the lunar surface and most exposures of the ancient anorthositic crust are concentrated in regions of thicker crust surrounding impact basins on the lunar nearside and farside in addition the scale of the impact basins and the global nature and distribution of pure plagioclase requires a coherent zone of anorthosite of similar composition in the lunar crust supporting its formation from a single differentiation event like a magma ocean our identifications of pure anorthosite combined with the grail crustal thickness model suggest that pure anorthosite is currently observed at a range of crustal thickness values between 9 and 63 km and that the primary anorthositic crust must have been at least 30 km thick

eddy shedding from the upper tropospheric asian monsoon anticyclone abstract the authors investigate the transient behavior of the asian monsoon anticyclone in the summertime upper troposphere for the four northern summers 1987 90 the evolution of potential vorticity near the tropopause shows the development of westward migrating anticyclones breaking off from the main anticyclone a few times each summer these disturbances are relatively shallow being confined to the upper troposphere

quantitative seismic pre stack analysis of potential gas hydrate resources in the makran accretionary prism offshore iran abstract gas hydrates are classified as a major unconventional resource and assumed to be a future potential energy source high pressures low temperature stability conditions of the hydrates restrict their occurrence to the permafrost and deep sea regions from the continental slop to the abyssal in these regions where the well information is most often absent or sparse the amplitude variation with angle ava is a common method of hydrate free gas assessment in this method various linear reflection coefficient equations are fitted to a series of data points to compute some pre stack attributes these attributes have the advantage of being an interface property rather than a layer property which makes them an easy to use characterization tool in lack of well data in recent years rock physics templates nomograms have been presented to estimate the hydrate free gas saturations solely based on these interface properties ava inversion approach was applied to the seismic data in the makran accretionary prism offshore iran to estimate the bottom simulating reflector bsr vicinity hydrate and gas saturations this inversion process included four pre stack attributes of the intercept gradient normal incidence ni and poisson reflectivity pr and was limited to the bsr estimated bsr vicinity saturations were ranged from 7 8 5 for hydrate and 5 6 5 for free gas at three representative locations accuracy of each attribute was analyzed by a synthetic modeling in this modeling the effective medium theory emt was considered to calculate the physical properties of hydrate and gas bearing sediments lithological properties and the acquisition geometry were set to the corresponding values of the field data results of the synthetic ava inversion showed that if the hydrate saturation does not exceed 30 the error of the estimation for pre stack attributes would be in acceptable range the expected estimation errors for actual attributes were derived from this synthetic modeling

discrimination between maturity and composition of lunar soils from integrated clementine uv visible near infrared data application to the aristarchus plateau the reflectance spectrum of a lunar soil is mainly dominated by the composition and the degree of exposure to space weathering processes such as micrometeorite bombardment and solar wind implantation the spectral alteration effects of space weathering should be removed for accurately investigating the composition of the lunar surface using remote sensing data in this paper we show that the integration of the clementine uv visible uvvis and near infrared nir channels provides an improved evaluation of the spectral alteration the depth of the mafic absorption feature at 0 95 m is also better defined by combining the uvvis and nir data laboratory spectra of lunar soil samples indicate that the continuum slope derived from the 1500 750 nm ratio is closely related to the concentration of fine grained submicroscopic iron is the continuum slope therefore provides an evaluation of the spectral alteration of the surface which can be subtracted from the 1 or 2 m absorption band depths to retrieve compositional information this method has been applied to the aristarchus plateau which exhibits a broad range of mineralogical composition and maturity a nine channel multispectral mosaic of 680 clementine images of the aristarchus plateau has been processed eight telescopic spectra have been used to check the validity of the reduction process for the near infrared bands the 1 m absorption band once corrected for spectral alteration provides an evaluation of the initial feo content in mafic silicates mafic iron lunar soil samples show that it is possible to quantitatively map mafic iron with this technique our results are in good agreement with those obtained using the algorithm of lucey et al 1995 1998a which is based on uvvis bands alone the mafic iron content and total iron content which can be derived from the combined uvvis and nir data sets are less sensitive to local slopes than that derived from lucey et al s method this new method could therefore be useful for investigating areas at middle to high latitudes removing spectral alteration from the 2000 1500 nm ratio also makes possible a better discrimination between olivine and pyroxene within identified mare basalts on the aristarchus plateau

galileo imaging observations of lunar maria and related deposits the galileo spacecraft imaged parts of the western limb and far side of the moon in december 1990 ratios of 0 41 0 56 gin filter images from the solid state hnaging ssi experiment provided information on the titanium content of mare deposits ratios of the 0 76 0 99 gm images indicated 1 gin absorptions associated with fe 2 in mafic minerals mare ages were derived froin crater statistics obtained from lunar orbiter images results on mare coinpositions in western oceanus procellarum and the humorurn basin are consistent with previous earth based observations thus providing confidence in the use of galileo data to extract compositional information mare units in the grimaldi and riccioli basins range in age froin 3 25 to 3 48 ga and consist of medium to medium high titanium 4 to 7 tio2 content lavas the schiller zucchius basin shows a higher 0 76 0 99 gm ratio than the surrounding highlands indicating a potentially higher mafic mineral content consistent with previous interpretations that the area includes mare deposits blanketed by highland ejecta and light plains materials the oldest mare materials in the orientale basin occur in south central mare orientale and are 3 7 ga old youngest mare materials are in lacus autumni and are 2 85 ga old these units are medium to medium high titanium 4 to 7 tio2 basalts thus volcanism was active in orientale for 0 85 ca but lavas were relatively constant in composition galileo data suggest that mendel rydberg mare is similar to mare orientale cryptomare are present as well thus the mare lavas on the western limb and far side to 178oe are remarkably uniform in coinposition being generally of medium to medium high titanium content and having relatively low 0 76 0 99 gin ratios this region of the moon is between two postulated large impact structures the procellarum and the south pole aitken basins and may have a relatively thick crust in areas underlain by an inferred thinner crust i e zones within large basins as at apollo titanium content is often higher however no mare deposits with titanium abundances approaching those of the high titanium 9 to 14 tio2 apollo 11 and 17 basalts nor of the high titanium regions of central oceanus procellarum are seen on the western limb or eastern far side light plains deposits are generally indistinct froin the surrounding highlands in the ssi data and are inferred to be derived primarily from the same material that forins the highlands some of the light plains are too young to be related to basin forming impacts suggesting possible volcanic origin dark mantle deposit compositions derived from ssi data are consistent with earth based observations of similar near side deposits and are interpreted to be pyroclastic materials however the modernitc albedo and 1 gin absorption of the dark mantle deposit on the southwest margin of the orientale basin suggest it is a local pyroclastic deposit contaminated with underlying highland materials from the orientale impact

the imbrium impact event and the thorium distribution at the lunar highlands surface late in the moon s heavy bombardment period the impact that formed the imbrium basin excavated and melted a tremendous volume of material that was subsequently distributed over most of the moon s surface the apollo orbiting ray experiments metzger et al 1977 show that the imbrium projectile struck in a th rich area called the high th oval region here and regarded as a unique lunar geochemical province imbrium primary ejecta were thus probably rich in th it is shown here using ejecta deposit modeling that the distribution of th in the highlands surface along the ground tracks of the ray spectrometers is consistent with the distribution expected for imbrium ejecta deposits deep basins other than imbrium appear to have excavated regions of lower crust that were mafic and fe bearing but not th rich the possibility that the surface th distribution arises mainly from imbrium ejecta has implications for the nature of the moon s igneous differentiation and the nature of the proposed cataclysm or late bombardment with large meteoroids

the effect of interpolation on imaging and avo a viking case study the use of prestack interpolation prior to prestack migration to improve avo analysis on image gathers is demonstrated on an exploration play the interpolation achieves this improvement by reducing migration artifacts avo analysis attempts to estimate fundamental information from surface seismic data and likely will be used more frequently if the estimates can be more accurately produced land 3d seismic typically has poor and irregular sampling this poor sampling creates migration noise which is a material cause of inaccurate avo estimates prestack 5d interpolation is applied prior to prestack migration and avo analysis on the imaged gathers to address this noise problem the interpolation algorithm includes offset and azimuth dimensions that preserve avo information this method is evaluated bycomparing the results to those of alternate approaches such as superbinning that suppress this kind of noise in avo analysis the evaluation is determined by comparing our ability to predict the reservoir q

absolute and convective instability of the african easterly jet abstractthe stability of the african easterly jet aej is examined using idealized numerical simulations it is found that a zonally homogeneous representation of the aej can support absolute instability in the form of african easterly waves aews this finding is verified through a local energy budget which demonstrates the presence of both upstream and downstream energy fluxes these energy fluxes allow unstable wave packets to spread upstream and downstream relative to their initial point of excitation this finding is further verified by showing that the ground relative group velocity of these wave packets has both eastward and westward components in contrast with normal mode instability theory which emphasizes wave growth through energy extraction from the basic state the life cycle of the simulated aews is strongly governed by energy fluxes convergent fluxes at the beginning of the aew storm track generate new aews whereas divergent fluxes at the end of the storm track lead to their decay i

compositional gradients across mare highland contacts importance and geological implication of lateral transport observations of mixing across mare highland contacts using high resolution clementine data allow a new assessment of the relative importance of vertical versus lateral mass transport on the moon at least at mare highland contact we analyze mare highland contacts in the grimaldi orientale and fecunditatis basins and tsiolkovsky crater through image based nonlinear spectral mixture modeling of clementine ultraviolet visible uv vis light spectrometer multi spectral data the mare in these regions differ in ages but they are characterized by having simple geological contacts the symmetric distribution of mare and highland soil constituents across their geological contact indicates that lateral transport is more efficient than deep vertical transport during the formation of the observed mixing zones observations across the lunar limb with the clementine uv vis filters show that there is a stray light component of scattered light across high contrast albedo boundaries however the magnitude and spatial properties of scattered light do not significantly affect the nature of compositional boundaries determined here since repetitive meteorite bombardment governs lateral transport across the geological contacts and is a random process a stochastic model is developed to describe this lateral transport analysis of the power decay law for crater ejecta thickness indicates that the high velocity ejecta travels long distances and follows a 3 power decay law this results in an infinite variance which requires an anomalous diffusion model since a classical diffusion model would be invalid mathematical modeling supports this result where it is shown that classical diffusion produces a relatively poor fit to profiles of material abundance while the anomalous diffusion model fits the profiles adequately these results indicate that high velocity ejecta dominates the formation of the observed compositional gradients while the ejecta near the crater rim is relatively less important on the basis of these ejecta distributions and the assumption of random impact cratering we derive a relationship that can be used as an index for relative age dating of geological contacts as well as for investigating cratering rates

spectral reflectance studies of the grimaldi region of the moon near infrared reflectance spectra were used to investigate the composition and origin of the various geologic units in the grimaldi region as well as the stratigraphy of the grimaldi pre impact target site the results of our spectral analysis indicate that the portions of the hevelius formation that occur in the grimaldi region are composed of noritic anorthosite and anorthositic norite gabbroic material was excavated from beneath orientale related units by small impact craters in three areas in the grimaldi region the primary ejecta deposits of the grimaldi basin as well as the pre orientale floor unit are dominated by noritic anorthosite and anorthositic norite the peak ring of grimaldi is composed at least in part of pure anorthosite the anorthosites on the inner ring and elsewhere within grimaldi were derived from a layer of pure anorthosite that exists at depth beneath a more pyroxene rich unit

remote sensing studies of the orientale region of the moon a pre galileo view we have acquired both an extensive data base of visible and near infrared spectra and multispectral images ultraviolet and visible of the orientale region of the moon our results show that the eastern inner rook mountains are composed of anorthosite portions of the main ring of the humorum basin and the inner ring of grimaldi are also composed of anorthosite other deposits within the orientale basin and the major ejecta unit outside the basin are dominated by noritic anorthosites mature surfaces have spectra nearly identical to those taken of areas in the vicinity of the apollo 16 site thus it appears that orientale ejecta are more mafic than materials that are thought to have originated at depth i e the anorthosites in the inner rook mountains there are large areas that have mare basalt signatures mixed with highland rock types indicating the existence of ancient pre orientale mare volcanism present mare surfaces in the orientale region contain basalts of intermediate to very low tio2 content

radiative transfer model constraints on the shock state of remotely sensed lunar anorthosites 1 near ir spectra of some lunar basin rings and crater central peaks exhibit no evidence of absorption due to ferrous iron unlike all other spectral measurements of lunar soil in the laboratory or obtained remotely these spectral anomalies have previously been interpreted to indicate the presence of a deposit of essentially pure plagioclase feldspar anorthosite which has been shocked above 250 kb plagioclase possesses a diagnostic absorption feature near 1250 nm caused by trace ferrous iron that is lost when shocked above 250 kb whereas ferrous features of pyroxene are robust against shock however new methods for computing the optical effects of exposure of lunar materials to the space environment show that these optical effects can obscure the spectral features of plagioclase without resorting to shock modification of the plagioclase structure our modeling shows that shock is not necessary to explain the apparent lack of absorption but is not excluded either thus previous reports that some lunar surface features may have experienced high shock levels are not supported

lunar impact basins new data for the western limb and far side orientale and south pole aitken basins from the first galileo flyby compositional aspects of impact basin materials can be analyzed using multispectral image data acquired by the galileo solid state imaging ssi experiment during the december 1990 lunar encounter these data provide important information on the spectral properties of the western lunar limb and parts of the far side the ssi images cover the wavelength range 0 4 1 0 m allowing measurement of spectral slope and estimation of the strength of the 1 m absorption due to iron in the mafic minerals olivine and pyroxene among deposits of the 930 km diameter orientale basin exterior ejecta comprising the hevelius formation is relatively homogeneous and spectrally similar to mature apollo 16 soils suggesting an upper crustal source the centrally located maunder formation is distinct from the younger mare basalts but comparable to the hevelius formation in its spectral reflectance properties supporting an interpretation as basin impact melt the montes rook formation located in an annulus between the maunder and the hevelius shows a slightly stronger mafic absorption and may be the deepest crustal material excavated the distal orientale deposits show local mafic enhancements in the schiller schickard and mendel rydberg regions interpreted to represent pre orientale mare deposits or cryptomaria intermixed with overlying basin ejecta in this case maria of sizes comparable to those presently observed were widespread in this region before the orientale impact mixing model analyses are consistent with the ballistic erosion and sedimentation model for ejecta emplacement in the distal regions beyond the continuous ejecta deposit on the southern lunar farside a huge area with an enhanced mafic absorption corresponds to the interior and rim of the pre nectarian south pole aitken impact basin 2000 2500 km in diameter the anomaly is interpreted to be due to several factors including excavation into the more mafic lower crust and the presence of extensive early volcanic fill cryptomare similar to that seen in ancient basins such as smythii and australe these results show that although basin forming events are an important factor in producing lateral heterogeneities in crustal composition and in modifying preexisting deposits such as cryptomaria the majority of material in even the largest basins was excavated from crustal levels our results suggest a gradational vertical crustal stratigraphy consisting of an uppermost mixed crustal layer of anorthosite basin ejecta and cryptomaria deposits generally corresponding to the megaregolith an upper crustal layer of anorthosite and a lower more noritic layer many of the basic questions remaining from this study could be addressed by global high resolution geochemical and mineralogical data obtained by polar orbiting spacecraft

remote sensing studies of the terrain northwest of humorum basin we have used near infrared reflectance spectra and earth based radar data to investigate the composition and origin of the various geologic units northwest of humorum basin as well as the stratigraphy of the humorum pre impact target site the results of our spectral analysis indicate that at least a portion of the inner mare bounding ring is composed of pure anorthosite other highlands units in the region are dominated by noritic anorthosite the anorthosites on the inner ring may have been derived from a layer of anorthosite that exists at depth beneath a more pyroxene rich unit both gassendi g and f craters expose mare material from beneath a highlands rich surface unit that was emplaced as a result of the letronne gassendi and other impact events this ancient basalt unit was emplaced after the formation of humorum basin but prior to the orientale impact

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

nonlinear spectral mixture modeling of lunar multispectral data implications for lateral transport linear and nonlinear spectral mixture models applied to clementine multispectral images of the moon result in roughly similar spatial distributions of end member abundances however there are important differences in the absolute values of the predicted abundances the magnitude of these differences and the implications for understanding geological processes are investigated across a geologic contact between mare and highland in the grimaldi basin on the western nearside of the moon vertical and lateral mass transport due to impact cratering has redistributed mare and highland materials across the contract creating a gradient in composition solutions to linear and nonlinear spectral mixture models for identical spectral end members of mature mare mature highland and fresh crater materials are compared across this simple geologic contact in the grimaldi basin formal estimates of uncertainty in the calculated fractions of the end members are 1 profiles of mare abundance across the contact are extracted and compared quantitatively profiles from the linear mixture models indicate that the geologic contact has an average mare abundance of 60 and the compositional boundary is asymmetric with more mare transported onto the highland side of the contact than highland onto the mare side of the contact in contrast the nonlinear abundance profiles indicate that the geologic contact has an average mare abundance of 50 and the compositional boundary is remarkably symmetric given the expectation that materials will be intimately mixed on the surface of the moon and that the asymmetries implied by the linear model are not consistent with our understanding of lunar surface processes the non linear spectral mixture model is preferred and should be applied whenever quantitative abundance information is required the remarkable symmetry in the compositional gradients across this contact indicates that lateral mass transport dominates over vertical transport at this boundary

remote sensing of lunar pyroclastic mantling deposits abstract mantling deposits on the moon are considered to be pyroclastic units emplaced on the lunar surface as a result of explosive fire fountaining these pyroclastic units are characterized as having low albedos having smooth fine textured surfaces and consisting in part of homogeneous febearing volcanic glass and partially crystallized spheres mantling units exhibit low returns on depolarized 3 8 cm radar maps indicating an absence of surface scatterers in the 1 to 50 cm size range a number of reflectance spectra from several regional pyroclastic deposits are presented for the first time these data support a previous interpretation that mantling units have a unique spectral signature which is indicative of the presence of a significant fe bearing volcanic glass component the rima bode region is discussed as an example of an area in which several types of remote sensing data including 3 8 cm radar spectral reflectance and multispectral vidicon data were used to reconstruct the geologic events surrounding the emplacement of a regional pyroclastic mantling deposit the recognition of numerous varieties of volcanic glass samples especially relatively high albedo e g green yellow glasses suggests the existence of additional unrecognized mantling deposits with albedos higher than those studied to date on the basis of the remote sensing data summarized and presented five new areas have been identified which may represent higher albedo regional pyroclastic deposits

the aristarchus impact event and the effects of target material the relatively well preserved 42 km diameter lunar impact crater aristarchus was excavated across the boundary between the aristarchus plateau and the mare plains previous geological mapping of the different ejecta facies associated with aristarchus has shown that there are distinct morphological differences between ejecta emplaced on either side of the fault scarp that separates the plateau from the mare one explanation of this observation is that ejecta behaved in different ways on emplacement depending on the original lithology of the excavated material to test this proposal we examine the pre aristarchus regional stratigraphy and identify the spectral signatures of each of the material s units by comparing these data with analysis of the geology and spectral characteristics of the ejecta units we are able to show the provenance of each of the mappable ejecta facies the conclusions are consistent with the concept of the crater ejecta asymmetry being related to bedrock characteristics using geological mapping spectral interpretation and present understanding of the impact cratering process we reconstruct the impact event and suggest how such techniques could be used further to interpret the moon s composition and history

compositional diversity and geologic insights of the aristarchus crater from moon mineralogy mapper data 1 the moon mineralogy mapper m3 acquired high spatial and spectral resolution data of the aristarchus plateau with 140 m pixel in 85 spectral bands from 0 43 to 3 0 m the data were collected as radiance and converted to reflectance using the observational constraints and a solar spectrum scaled to the moon sun distance summary spectral parameters for the area of mafic silicate 1 and 2 m bands were calculated from the m3 data and used to map the distribution of key units that were then analyzed in detail with the spectral data this analysis focuses on five key compositional units in the region 1 the central peaks are shown to be strongly enriched in feldspar and are likely from the upper plagioclase rich crust of the moon 2 the impact melt is compositionally diverse with clear signatures of feldspathic crust olivine and glass 3 the crater walls and ejecta show a high degree of spatial heterogeneity and evidence for massive breccia blocks 4 olivine strongly concentrated on the rim wall and exterior of the southeastern quadrant of the crater is commonly associated the impact melt 5 there are at least two types of glass deposits observed pyroclastic glass and impact glass

the response to mjo like forcing in a nonlinear shallow water model this study examines the response to madden julian oscillation mjo like heat forcing in a nonlinear shallow water model including monopolar heating source traveling eastward with an around the world period of 48 days and dipolar heating with zonal wave period of 48 days with zonal wave number 2 confined in longitude to the mjo active regions a jet localized in the pacific is compared to a zonally uniform boreal basic flow the results show that the rossby wave response downstream exhibits intensified quasi stationary anomalies in the pacific jet exit region when the mjo like heat forcing passes the maritime continent in accord with the observational analysis by adames and wallace 2014 the dynamical mechanism suggested in this study can be used to interpret the intraseasonal mjo pacific north american pattern coherence and other extratropical intraseasonal events