application of extended empirical orthogonal function analysis to interrelationships and sequential evolution of monsoon fields abstract extended empirical orthogonal function eeof analysis has been employed to study linear relationships among the mean sea level pressure 700 mb height and rainfall over india and their low frequency sequential evolution during the peak summer monsoon months the interrelationships between these fields are strongest over central india and while the rainfall activity is colocated with the corresponding changes in the 700 mb heights it is displaced southward with respect to the pressure changes the first two eeof s of all the three fields averaged over 5 or 7 days show that the dominant low frequency sequential evolution is associated with north and northeastward movement of the anomaly centers with a recurrence period of about 40 days in addition the presence of a westward moving wave in sea level pressure anomalies located roughly near 15 n latitude is revealed by the third eeof

merging spatial and spectral datasets to place olivine in stratigraphic context at arruntia crater a rare window into vesta s northern hemispheric crust abstract a major goal of the dawn mission to vesta was to test and refine current models of the asteroid s formation by characterizing the distribution of mineral components on its surface detection of the mineral olivine by the visible and infrared mapping spectrometer vir and the framing camera fc onboard dawn was a key milestone in this effort and was expected to help resolve a debate regarding the dominant mode of vesta s petrologic evolution i e magma ocean vs serial magmatism however the subtleties of the olivine spectral signature combined with the small size of individual olivine rich exposures tens of meters prohibits detailed mapping of this petrologically significant mineral component when the data from either instrument are evaluated independently as a result the particular role of these olivine exposures in vesta s geologic history remains largely unresolved here we fully characterize the type locality of vesta s olivine rich materials the northern hemisphere craters bellicia and arruntia using a novel data fusion approach for linking the vir and fc datasets specifically we have leveraged a spectral mixture analysis framework to create a new dataset that maps or extrapolates full resolution spectra derived from vir data onto the higher spatial resolution of fc when used as an exploratory tool in conjunction with the original fc and vir data the new extrapolated dataset reveals important new details about the distribution of olivine around bellicia and arruntia craters there are clear compositional distinctions between the exposures at the two craters with a much stronger olivine component in the walls of bellicia than arruntia the proximal arruntia ejecta appear more consistent with high proportions of an evolved high calcium pyroxene as in eucrites than with an enhanced olivine component examples of diogenite rich howardite also occur in the region further we leverage arruntia s role as the freshest large crater in the northern hemisphere and thus a rare window into the vesta s northern hemispheric crust to suggest an overall stratigraphy for the region a thin veneer of howardite overlies a sequence of diogenite rich near surface olivine rich intermediate and eucrite rich materials at depth the manner of exposure of these various components in a marked stratification point to a plutonic model for emplacing these mineralogically unique components in the near surface of vesta

petrogenetic relationships between diogenites and olivine diogenites implications for magmatism on the hed parent body abstract diogenites are orthopyroxenites and harzburgites that are petrogenetically associated with basaltic magmatism linked to the earliest stages of asteroidal melting on the parent body for the howardite eucrite diogenite hed meteorites there are several models proposed for their origin 1 accumulation of orthopyroxene opx chromite chr olivine ol during the crystallization of a magma ocean during the initial stages of asteroidal differentiation 2 accumulation of opx chr ol during the crystallization of compositionally distinct basaltic magmas emplaced into the crust of the hed parent body and 3 the orthopyroxenites formed by the crystallization of basaltic magmas within the hed parent body crust whereas the harzburgites represent the mantle of the hed parent body although ol and opx experienced varying degrees of subsolidus reequilibration 1100 700 c their minor and trace element characteristics appear to partially preserve magmatic signatures that provide insights into distinguishing among different models for the origin of diogenites the opx exhibits a continuous and very systematic variation in incompatible elements such as al ti zr y and yb polymict diogenites i e roda eet 79002 can contain distinct lithologies with both different incompatible element characteristics and different model abundances of ol there appears to be no relationship between the appearance and abundance of ol and the incompatible element characteristics of the opx the ol exhibits a range in mg and systematic variations ni co ni co and mn for examples low ni co appears to be closely associated with the harzburgites and ni and mn exhibit a negative correlation surprisingly incompatible element concentrations in opx are not negatively correlated to ni concentrations in ol the continuous nature of the minor and trace element characteristics of the opx and ol is consistent with the all the diogenite lithologies forming through a single process such as crystallization within a magma ocean or a series of layered intrusions further the range in incompatible element variability in the opx the ni and co systematics in the ol and the association of distinctly different lithologies within polymict diogenites are most consistent with the diogenites representing lithologies from diverse layered intrusions alternatively they may represent crystallization products of a magma ocean much more complex than has been thus far proposed i e multiple mos there are some distinct differences between diogenites and the ol rich achondrite que 93148 that was also analyzed during this study these differences such as ni co in ol estimated conditions of fo2 suggest that que 93148 is closely related to main group pallasites rather than the parent bodies for the hed meteorites

processes of 30 90 days sea surface temperature variability in the northern indian ocean during boreal summer during summer the northern indian ocean exhibits significant atmospheric intraseasonal variability associated with active and break phases of the monsoon in the 30 90 days band in this paper we investigate mechanisms of the sea surface temperature sst signature of this atmospheric variability using a combination of observational datasets and ocean general circulation model sensitivity experiments in addition to the previously reported intraseasonal sst signature in the bay of bengal observations show clear sst signals in the arabian sea related to the active break cycle of the monsoon as the atmospheric intraseasonal oscillation moves northward sst variations appear first at the southern tip of india day 0 then in the somali upwelling region day 10 northern bay of bengal day 19 and finally in the oman upwelling region day 23 the bay of bengal and oman signals are most clearly associated with the monsoon active break index whereas the relationship with signals near somali upwelling and the southern tip of india is weaker in agreement with previous studies we find that heat flux variations drive most of the intraseasonal sst variability in the bay of bengal both in our model regression coefficient 0 9 against 0 25 for wind stress and in observations 0 8 regression coefficient 60 of the heat flux variation is due do shortwave radiation and 40 due to latent heat flux on the other hand both observations and model results indicate a prominent role of dynamical oceanic processes in the arabian sea wind stress variations force about 70 100 of sst intraseasonal variations in the arabian sea through modulation of oceanic processes entrainment mixing ekman pumping lateral advection our 100 km resolution model suggests that internal oceanic variability i e eddies contributes substantially to intraseasonal variability at small scale in the somali upwelling region but does not contribute to large scale intraseasonal sst variability due to its small spatial scale and random phase relation to the active break monsoon cycle the effect of oceanic eddies however remains to be explored at a higher spatial resolution

evaluation of depth of closure using data from duck nc usa using 12 years of frequent high precision profiles collected on a wave dominated sandy oceanic beach to 8 m depth the characteristics and interpretation of depth of closure or the seaward limit of significant profile change is critically examined this includes evaluation of the predictive capability of d1 the seaward boundary of the littoral zone as originally defined by hallermeier 1981 hallermeier r j 1981 a profile zonation for seasonal sand beaches from wave climate coastal eng 4 253 277 depth of closure during major erosional events is usually produced by the seaward limit of offshore bar movement following the original recommendation of hallermeier 1981 d1 based on 12 h exceeded wave height and a reference depth of mean low water provides a robust limit to the observations using a 6 cm change criterion empirically the observed depth of closure is 69 of d1 although the scatter is large this scatter is partly controlled by pre event profile shape most particularly bar configuration depth of closure under accretional conditions can also be measured but it is time scale dependent as accretion is a slow steady process d1 underpredicts closure for accretional situations time interval e g annual depth of closure represents the integral effect of erosional and accretional events an important observation of the data is that depth of closure increases with time scale however the full population of time interval observations is not resolved at duck due to the measurement limit 8 m depth as time interval increases from 1 year to 8 years less cases close most non closing time interval cases coincide with the periods influenced by the most energetic wave events however time interval closures are generally deeper than the biggest event closure in the period showing that it represents more than the largest event the frequency distribution of the data suggests that most if not all of these missing data simply represent closures deeper than 8 m depth up to a 4 year time interval d1 t appears to provide a reasonable limit to the quantified observations it is an interesting result that d1 an event based approach might provide a limit to closure over periods up to 4 years as these time interval closures are generally larger than those produced by single storms therefore the general applicability of this result for more complete data sets or on rapidly evolving i e eroding or accreting coasts is uncertain the present data also suggest that on swell dominated coastlines where accretional processes are dominant d1 may underpredict closure suggesting an important limitation to this approach but as sediment would be moving onshore this may not be a practical problem therefore within the limits of the data set hallermeier s 1981 approach is found to define robust estimates of depth of closure particularly for individual erosional events this useful result is expected to find widespread application in coastal geology and engineering

the indian monsoon and its variability for over 300 years the monsoon has been viewed as a gigantic land sea breeze it is shown in this paper that satellite and conventional observations support an alternative hypothesis which considers the monsoon as a manifestation of seasonal migration of the intertropical convergence zone itcz with the focus on the indian monsoon the mean seasonal pattern is described and why it is difficult to simulate it is discussed some facets of the intraseasonal variation such as active weak cycles break monsoon and a special feature of intraseasonal variation over the region namely poleward propagations of the itcz at intervals of 2 6 weeks are considered vertical moist stability is shown to be a key parameter in the variation of monthly convection over ocean and land as well as poleward propagations special features of the bay of bengal and the monsoon brought out by observations during a national observational experiment in 1999 are briefly described

the analysis of beach profile changes using dean s method and empirical orthogonal functions abstract sea bottom changes in the cross shore direction have been analysed the cross shore profile as a major factor of beach configuration has been presented schematically as a superposition of a basic curve reflecting the mean layout and slope of the shore given by dean s function y a 2 3 and superimposed various bars troughs berms etc depicting local characteristic features of the profile the local features of the profile have been analysed by use of one 1 d and two dimensional 2 d empirical orthogonal functions on the basis of field observations and measurements the parameter a has been presented as a function of time three time scales have been distinguished short seasonal and long term with respect to which more or less regular changes of the parameter a occur the modified parameter a was applied to two different field sites namly lubiatowo baltic sea poland and gold beach black sea bulgaria it has been found that in extreme cases the parameter a can vary in time by a factor of two or more for the same grain size distribution

exogenic olivine on vesta from dawn framing camera color data abstract in this paper we present the results of a global survey of olivine rich lithologies on 4 vesta we investigated dawn framing camera fc high altitude mapping orbit hamo color cubes 60 m pixel resolution by using a method described in thangjam et al thangjam g nathues a mengel k hoffmann m schafer m reddy v cloutis e a christensen u sierks h le corre l vincent j b russell c t 2014b meteorit planet sci arxiv 1408 4687 astro ph ep in total we identified 15 impact craters exhibiting olivine rich 40 wt ol outcrops on their inner walls some showing olivine rich material also in their ejecta and floors olivine rich sites are concentrated in the bellicia arruntia and pomponia region on vesta s northern hemisphere from our multi color and stratigraphic analysis we conclude that most if not all of the olivine rich material identified is of exogenic origin i e remnants of a or and s type projectiles the olivine rich lithologies in the north are possibly ejecta of the 90 km diameter albana crater we cannot draw a final conclusion on their relative stratigraphic succession but it seems that the dark material nathues a hoffmann m cloutis e a schafer m reddy v christensen u sierks h thangjam g s le corre l mengel k vincent j b russell c t prettyman t schmedemann n kneissl t raymond c gutierrez marques p hall i buttner i 2014b icarus 239 222 237 and the olivine rich lithologies are of a similar age the origin of some potential olivine rich sites in the rheasilvia basin and at crater portia are ambiguous i e these are either of endogenic or exogenic origin however the small number and size of these sites led us to conclude that olivine rich mantle material containing more than 40 wt of olivine is basically absent on the present surface of vesta in combination with recent impact models of veneneia and rheasilvia clenet h jutzi m barrat j a gillet ph 2014 lunar planet sci 45 1349 jutzi m asphaug e gillet p barrat j a benz w 2013 nature 494 207 210 which predict an excavation depth of up to 80 km we are confident that the crust mantle depth is significantly deeper than predicted by most evolution models 30 km mittlefehldt d w 2014 asteroid 4 vesta a fully differentiated dwarf planet nasa technical reports server 20140004857 pdf or alternatively the olivine content of the upper mantle is lower than our detection limit which would lead to the conclusion that vesta s parent material was already depleted in olivine compared to ci meteorites

simulation of large scale coastal change using a morphological behaviour model abstract quantitative simulation of large scale coastal behaviour lscb is possible using a model based only on principles of sand mass conservation and geometric rules for shoreface and active sand body morphology dynamic processes are subsumed into a set of parameters that define the geometry of the active cross shore profile which in turn can represent an entire coastal cell the parameters together with a set of local behaviour rules governing adjustments at discrete points along the profile provide a simple formulation that is constrained by sediment mass balance to yield emergent numerical solutions for profile kinematics the emergent qualities of this shoreface translation model are exemplified in simulation experiments on changes to sand deposits on the southeastern australian coast and shelf during the post glacial marine transgression in another example the model is used to simulate lscb over engineering time scales at an idiosyncratic site both examples illustrate the over riding importance of small residual sand movements that accumulate through time to cause lscb in comparison to gross sand movements the residuals are too small to measure directly or predict on the basis of available theory exploratory inverse simulation provides a quantitative method for side stepping these limitations the shoreface translation model therefore is used as a tool to explore possible forms of coastal behaviour through an approach that incorporates available data along with theoretical considerations validation is not strictly possible for this type of inverse approach so the degree to which a simulation reproduces observed features in nature is a measure of its success

postglacial evolution of coastal barriers along the west pomeranian coast ne germany abstract the aim of this study is to present an evolutionary model of the coastal barriers in west pomerania regarding both morphological development and chronostratigraphy the study area is situated on the islands of rugen and usedom in the tideless sw baltic to reconstruct the geological setting 250 cores were collected 20 new radiocarbon dates allow a description of the late pleistocene to holocene evolution of the barriers in all areas investigated the lithofacies sequences are similar which enables the derivation of a general evolutionary model for the sw baltic sea coasts the controlling factors are the relief of the early holocene landscape as well as the sea level history of the baltic sea the base is made up of a pleistocene till the deposition of this till had already determined the configuration of the present day coast late pleistocene to early holocene freshwater deposits follow in the columnar section often overlain by peat during the main phase of the transgression 8000 6000 before present bp the early holocene landscape was drowned and mud accumulated in the depressions beach ridges attached to pleistocene headlands began to develop at 6000 bp simultaneously landward of the beach ridges sediment accumulated in wind flats this depositional environment which can still be recognised along the coast today is controlled by wind driven currents a second peat layer younger than 1000 bp makes up the uppermost part of the sequence in most of the lowland sites the evolution of the coastal barriers in west pomerania follows the scheme developed for tidal paraglacial coasts this study adjusts the scheme to the regional stratigraphy and extends it with regard to tideless conditions and the evolution of wind flats

coastline evolution at different time scales examples from the pomeranian bight southern baltic sea sedimentological and morphological changes on the upper and lower shoreface during relatively stable sea level highstand conditions have been investigated in the pomeranian bight southern baltic sea at time scales ranging from storm events to millennia in order to cover that variety of time scales different methods have been applied seasonal variations in the morphology of the upper shoreface were measured accurately using the tracer stick method the ratio of breaking waves and energy dissipation due to wave breaking are the main forces controlling redeposition on the upper shoreface with the depth of disturbance up to three times the net change the impact of single storm events can be observed from sidescan sonar mosaics to remain on the decadal scale aerial photographs covering the upper shoreface show that the location of gates channel like systems where water masses move offshore created during storm events also remain stable over decades sedimentological and geomorphological variations and changes on the lower shoreface are only measurable on the century to millennium scale because the main driving forces are longlasting processes like sea level fluctuations or neotectonics data on these scales have much more uncertainty in their relationship to forcing functions than data at shorter time scales because the effects of coastal processes active on different time scales can interact comprehensive understanding of large scale coastal behavior requires investigations from short events to long term processes c 2002 elsevier science b v all rights reserved

examination of mesoscale forcing of a swash aligned gravel barrier from nova scotia abstract the possibility by which the retreat of a swash aligned gravel barrier on nova scotia s atlantic coast may be influenced by varying mesoscale time domains of differential process conditions is examined tide gauge data are used to generate definition of mesoscale process domains regarded as influential in barrier behaviour semi diurnal high water tidal residuals from halifax nova scotia tide gauge 1920 1990 are characterised for both surge magnitude and frequency on an annual basis these two variables are combined to define three event types of annual surge histories first order n th step markov analyses show that significant memory exists in 6 year and 22 year transitions between surge event types the longer transition sequence mirrors a major decadal mesoscale domain change in surge generation which is suggested to be associated with phases of barrier crest reworking that enhance barrier retreat when the domain change occurs the shorter transition sequence may reflect cyclonic activity cycles on the scotian shelf superimposed on the longer term transition

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

relative sea levels and coastal sedimentation in southeast australia in the holocene abstract in recent years australian studies of relative sea level change have shown reasonable consistency on the termination date of the postglacial marine transgression at c 6 500 14c years bp the following stillstand period has been characterized in some regions by a slight falling trend from a high stand or in other areas by a level not easily distinguished from the present the latter situation occurs on the embayed coast of new south wales here studies of depositional environments and sequences within bed rock embayments have linked the holocene sea level history to patterns of sedimentation on the inner shelf in bay barriers and in estuaries deposition of quartz rich sand in shoreface flood tidal delta and backbarrier environments occurred during the marine transgre sion and the subsequent stillstand shell fragments from these deposits have been radiocarbon dated shoreline displacement continues to the present day partly in response to changes in availability of sand in the shoreface zone and partly in response to variations in regional storminess patterns a nd the great shroud of the sea rolled on as it rolled five thousand years ago herman melville moby dick

composition of the northern regions of vesta analyzed by the dawn mission abstract the surface composition of the northern regions of vesta observed by the dawn spacecraft offers the possibility to test several hypotheses related to impact related processes we used mostly imaging spectrometry in the visible and near infrared to assess the distribution of mafic lithologies hydrated components and albedo properties and use the link with howardite eucrite and diogenite meteorites heds to investigate the origin of those materials we established that rheasilvia ejecta reached part of the northern regions and have a diogenitic rich composition characteristic of the lower crust investigations of the antipodes of the two major impact basins rheasilvia and veneneia did not reveal any correlation between geographic location geological features and the surface composition the northern wall of mamilia crater which is one of the freshest craters above 22 n contains relatively pure eucritic rich diogenitic rich and dark hydrated materials which are representative of the rest of the northern regions and most of vesta with the exception of an olivine like component found in bellicia crater by ammannito et al ammannito e et al 2013a nature 504 7478 122 125 we determined that similar types of materials are found in various proportions over a large region including bellicia arruntia and pomponia craters and their origin does not seem to be related to rheasilvia ejecta these materials are hydrated which could indicate an exogenous origin and not as dark as expected for carbonaceous chondrites which likely compose the majority of dark hydrated materials on vesta spectral mixture analysis reveals that mixtures of pyroxenes hypersthene pigeonite and diopside could offer an alternative interpretation to olivine in this area

application of multivariate statistical techniques in alongshore differentiation of coastal barriers abstract this paper investigates the existence of statistical correlations and relationships between geological and oceanographic parameters along a coastal barrier system in southern brazil the existence of few statistical studies on coastal barriers motivated the use of multivariate statistical techniques that take environmental parameters such as coastal morphological sedimentary features and their morphometric measurements into account the hierarchical cluster analysis hca and principal component analysis pca were used to assess the spatial variations of fourteen parameters driving the current and past behavior of this coastal barrier system at fourteen locations through the application of hca these locations were divided into four groups groups 1 2 3 and 4 the hca results were analyzed using pca the first pc1 and the second pc2 principal components together explained at least 76 4 of the variability of all four groups the most important geological and oceanographic parameters that were correlated to pc1 and pc2 were different in each group in general the shoreface slope and shoreface dimensions were common to all groups as pc1 correlated parameters being the most important ones regarding data variability in addition for the progradational groups 1 and 4 retrogradational group 2 and aggradational barriers group 3 pca indicated that shoreline orientation wave exposure and beach type are secondary but relevant factors controlling the past and current behavior of coastal barriers in southern brazil

real time multivariate indices for the boreal summer intraseasonal oscillation over the asian summer monsoon region the boreal summer intraseasonal oscillation bsiso of the asian summer monsoon asm is one of the most prominent sources of short term climate variability in the global monsoon system compared with the related madden julian oscillation mjo it is more complex in nature with prominent northward propagation and variability extending much further from the equator in order to facilitate detection monitoring and prediction of the bsiso we suggest two real time indices bsiso1 and bsiso2 based on multivariate empirical orthogonal function mv eof analysis of daily anomalies of outgoing longwave radiation olr and zonal wind at 850 hpa u850 in the region 10 s 40 n 40 160 e for the extended boreal summer may october season over the 30 year period 1981 2010 bsiso1 is defined by the first two principal components pcs of the mv eof analysis which together represent the canonical northward propagating variability that often occurs in conjunction with the eastward mjo with quasi oscillating periods of 30 60 days bsiso2 is defined by the third and fourth pcs which together mainly capture the northward northwestward propagating variability with periods of 10 30 days during primarily the pre monsoon and monsoon onset season the bsiso1 circulation cells are more rossby wave like with a northwest to southeast slope whereas the circulation associated with bsiso2 is more elongated and front like with a southwest to northeast slope bsiso2 is shown to modulate the timing of the onset of indian and south china sea monsoons together the two bsiso indices are capable of describing a large fraction of the total intraseasonal variability in the asm region and better represent the northward and northwestward propagation than the real time multivariate mjo rmm index of wheeler and hendon

observations of a convectively coupled kelvin wave in the eastern pacific itcz abstract a case study of a convectively coupled kelvin wave in the eastern pacific intertropical convergence zone itcz is presented as observed during the 1997 pan american climate studies pacs tropical eastern pacific process study tepps the large scale convective envelope associated with this disturbance with a zonal scale of approximately 1000 2000 km propagates eastward at 15 m s 1 along the mean convective axis of the itcz this envelope consists of many smaller scale westward moving convective elements with zonal scales on the order of 100 500 km as the convectively coupled kelvin wave disturbance propagates eastward it exerts a strong control on local convection radar and vertical profiler data collected aboard the noaa r v ronald h brown during the wave passage show that convection deepens rapidly as the kelvin wave approaches from the west progressing from isolated shallow cumuli to organized deep convective features within just 12 h initially rainfall in the vicinity of the s

spectroscopic characterization of mineralogy and its diversity across vesta the mineralogy of vesta based on data obtained by the dawn spacecraft s visible and infrared spectrometer is consistent with howardite eucrite diogenite meteorites there are considerable regional and local variations across the asteroid spectrally distinct regions include the south polar rheasilvia basin which displays a higher diogenitic component and equatorial regions which show a higher eucritic component the lithologic distribution indicates a deeper diogenitic crust exposed after excavation by the impact that formed rheasilvia and an upper eucritic crust evidence for mineralogical stratigraphic layering is observed on crater walls and in ejecta this is broadly consistent with magma ocean models but spectral variability highlights local variations which suggests that the crust can be a complex assemblage of eucritic basalts and pyroxene cumulates overall vesta mineralogy indicates a complex magmatic evolution that led to a differentiated crust and mantle

monsoons as eddy mediated regime transitions of the tropical overturning circulation monsoons are generally viewed as planetary scale sea breeze circulations caused by contrasts in the thermal properties between oceans and land surfaces that lead to thermal contrasts upon radiative heating1 2 but the radiative heating evolves gradually with the seasons whereas the onset of monsoon precipitation and the associated circulation changes such as reversal of surface winds occur rapidly3 4 here we use reanalysis data to show that the onset of the asian monsoon marks a transition between two circulation regimes that are distinct in the degree to which eddy momentum fluxes control the strength of the tropical overturning circulation rapid transitions of the circulation between the two regimes can occur as a result of feedbacks between large scale extratropical eddies and the tropical circulation5 using simulations with an aquaplanet general circulation model we demonstrate that rapid eddy mediated monsoon transitions occur even in the absence of surface inhomogeneities provided the planet surface has sufficiently low thermal inertia on the basis of these results we propose a view of monsoons in which feedbacks between large scale extratropical eddies and the tropical circulation are essential for the development of monsoons whereas surface inhomogeneities such as land sea contrasts are not

sediment budget calculation to estimate holocene coastal changes on the southwest baltic sea germany abstract the tide less sw baltic sea has a paraglacial coast alternating pleistocene cliff sections and holocene barrier systems separate shallow lagoons from the open sea more than 300 cores penetrating the holocene coastal sequence allowed for detailed reconstruction of the palaeogeographic evolution the sequence formed in response to transgression in the early holocene 8000 year bp the barrier cliff system evolution is described as four stages over these stages dependencies of sedimentation processes to the rate of sea level rise are obvious to reconstruct palaeo coast configurations mass balance calculations were applied retreating cliff sections are seen as the main source for coastal sediment starting from mapped volumes of sand incorporated in barriers cliff retreat in the last 8000 years is calculated to total 2400 m at maximum sediment supply to the coastal zone averaged over the larger part of the holocene is approximately three times smaller than for the last hundreds years this signals accelerated rise of sea level since c 1000 years and hints on what to expect when sea level rises faster in the future such will cause intensified coastal erosion and eventually the formation of new inlets a general drowning of the coastal landscape as observed in the early holocene is unlikely

remote influences on the indian monsoon low level jet intraseasonal variations a strong low level jet llj also known as the findlater jet develops over the arabian sea during the indian summer monsoon this jet is an essential source of moisture for monsoonal rainfall over the densely populated indian subcontinent and is a key contributor to the indian ocean oceanic productivity by sustaining the western arabian sea upwelling systems the llj intensity fluctuates intraseasonally within the 20 to 90 day band in relation with the northward propagating active and break phases of the indian summer monsoon our observational analyses reveal that these large scale regional convective perturbations only explain about half of the intraseasonal llj variance the other half being unrelated to large scale convective perturbations over the indian ocean we show that convective fluctuations in two regions outside the indian ocean can remotely force a llj intensification four days later enhanced atmospheric deep convection over the northwestern tropical pacific yields westerly wind anomalies that propagate westward to the arabian sea as baroclinic atmospheric rossby waves suppressed convection over the eastern pacific north american monsoon region yields westerly wind anomalies that propagate eastward to the indian ocean as dry baroclinic equatorial kelvin waves those largely independent remote influences jointly explain 40 of the intraseasonal llj variance that is not related to convective perturbations over the indian ocean i e 20 of the total with the northwestern pacific contributing twice as much as the eastern pacific taking into account these two remote influences should thus enhance the ability to predict the llj

temporal and spatial scales of beach profile change duck north carolina abstract an 11 year time series of high resolution beach profile surveys made on an atlantic ocean beach was analyzed for spatial and temporal characteristics of beach profile change approximately 300 profile surveys most extending from the dune to 8 m depth were available for the analysis on each of four cross shore lines together with electronically recorded and statistically processed wave time series from a nearshore gage located seaward of the survey site the profile survey data set was analyzed for such quantities as depth change frequency of depth change general seasonal shape of the profile seasonal depth change and change in the profile produced by extreme storms the morphodynamics of an inner and outer longshore bar were also examined including depth to bar crest bar height and length and speed of bar movement onshore and offshore several properties of depth change were related to wave characteristics representative results were average profile elevation change from 4 m to 4 m was symmetric about the mean sea level shoreline the average spring and autumn profile shapes were almost identical and occurred as transitional states between the summer and winter profile shapes the depth of active profile movement within survey accuracy of about 0 025 m was 4 m for the summer and 6 m for the winter and the 10 year frequencies of maximum absolute depth change in depths of 2 4 6 and 8 m were 1 64 1 38 0 22 and 0 12 m respectively a surprising result was that typical large storms transported sand into the nearshore from the seaward end of the profile from a depth of about 6 8 m

littorina and post littorina sedimentological processes in the odra channel in light of multidisciplinary investigations of a sediment core pomeranian bay southern baltic sea abstract a multi proxy study was performed on a gravity core supplemented by acoustics profiles and new radiocarbon dates of macrofossils found in the sedimentation history of the odra channel during the holocene the channel is located in the western part of pomeranian bay and was shaped by a pre odra river that flowed northwest along the peene valley and the eastern part of rugen island during a drop in yoldia sea level the acoustic profiling enabled identification of glacial till the baltic ice lake and littorina sediments the studied core penetrated only marine sediments deposited during littorina and post littorina stages and was the subject of grain size geochemical and diatom analyses the age of appearance of a marine environment in the studied area was estimated at 7200 yrs bp the performed studies enabled division of the core into three phases of environmental evolution the littorina i phase occurred during the time span 7200 6000 yrs bp and is described as a shallow water brackish basin with a low rate of sea level rise and favourable conditions for biogenic production the littorina ii phase dated at 6000 3800 yrs bp reflects a deep marine environment with relatively high salinity and greater current velocity and the last phase post littorina covered the last 3800 yrs bp and turned out to be a strongly energetic environment with decreasing salinity the change from littorina ii to post littorina phase correlates clearly with a change in the acoustic reflection core analyses could be associated with extreme stormy cold events known as bond events dated at 5900 5500 yrs bp and 4200 yrs bp evidencing the final destruction of the odra bank barrier

an ocean atmosphere interaction mechanism for the active break cycle of the asian summer monsoon a typical active break cycle of the asian summer monsoon is taken as beginning with maximum sst pentad 0 over the north bay of bengal when the oceans to its west and east from longitude 40 160 e and between latitudes 10 and 25 n area a also has maximum sst during this pentad the recently found cold pool of the bay of bengal between latitudes 3 n and 10 n has its minimum sst an area of convection takes genesis over the bay of bengal immediately after pentad 0 in the zone of large sst gradient north of the cold pool and it pulls the monsoon low level jetstream llj through peninsular india convection and the llj westerlies then spread to the western pacific ocean during pentads 1 4 taken as the active phase of the monsoon during which convection and llj have grown in a positive feed back process the cyclonic vorticity to the north of the llj axis is hypothesized to act as a flywheel maintaining the convection during the long active phase against the dissipating effect of atmospheric stabilization by each short spell of deep convection by the end of pentad 4 the sst over area a has cooled and the convection weakens there when the llj turns clockwise over the arabian sea and flows close to the equator in the indian ocean a band of convection develops at pentad 5 between the equator and latitude 10 s over the indian ocean and it is nourished by the cyclonic vorticity of the llj now near the equator and the moisture supply through it this is taken as the break monsoon phase lasting for about three to four pentads beginning from pentad 5 of a composite active break cycle of 40 day duration with reduced wind and convection over the area a during the break phase solar radiation and light winds make the sst there warm rapidly and a new active break cycle begins sst convection llj and the net heat flux at the ocean surface have important roles in this new way of looking at the active break cycle as a coupled ocean atmosphere phenomenon

dominant control of the south asian monsoon by orographic insulation versus plateau heating heat emitted from the tibetan plateau as dry heat and water vapour has long been assumed to be the main driver of the south asian summer monsoon but new work suggests that in fact it is the neighbouring mountains that are the major influence william boos and zhiming kuang use an atmospheric model to show that flattening the tibetan plateau has little effect on the monsoon so long as the himalayas and surrounding mountain ranges remain the plateau does boost rainfall locally along its southern edge but it is the build up of hot moist air over india insulated from colder drier air by the himalayas that drives large scale monsoon circulation the elevation of the tibetan plateau is thought to cause its surface to serve as a heat source that drives the south asian summer monsoon potentially coupling uplift of the plateau to climate changes on geologic timescales here however an atmospheric model is used to show that flattening of the tibetan plateau has little effect on the monsoon provided that the narrow orography of the himalayas and adjacent mountain ranges is preserved the tibetan plateau like any landmass emits energy into the atmosphere in the form of dry heat and water vapour but its mean surface elevation is more than 5 km above sea level this elevation is widely held to cause the plateau to serve as a heat source that drives the south asian summer monsoon potentially coupling uplift of the plateau to climate changes on geologic timescales1 2 3 4 5 observations of the present climate however do not clearly establish the tibetan plateau as the dominant thermal forcing in the region peak upper tropospheric temperatures during boreal summer are located over continental india south of the plateau here we show that although tibetan plateau heating locally enhances rainfall along its southern edge in an atmospheric model the large scale south asian summer monsoon circulation is otherwise unaffected by removal of the plateau provided that the narrow orography of the himalayas and adjacent mountain ranges is preserved additional observational and model results suggest that these mountains produce a strong monsoon by insulating warm moist air over continental india from the cold and dry extratropics these results call for both a reinterpretation of how south asian climate may have responded to orographic uplift and a re evaluation of how this climate may respond to modified land surface and radiative forcings in coming decades

impacts of human interventions on the evolution of the ria formosa barrier island system s portugal abstract human interventions on sandy barriers disturb natural barrier dynamics to the extent of having become key forces in modifying geomorphological evolution this work identifies natural and human induced drivers and analyses their importance to the multi decadal evolution of the ria formosa barrier island system in south portugal aerial photographs from the last six decades and historical maps are used to assess changes in cross shore rates morphological characteristics barrier and dune widths inlet morphology and migration and barrier areas through systematic methods that can be easily transferred to other barrier systems interventions and especially hard engineering ones jetties inlet stabilisations affected barrier evolution trends shore perpendicular works increased shoreline progradation updrift and initiated coastal retreat downdrift with strongest erosive impacts along the edges of the system inlet stabilisations changed tidal inlet hydrodynamics and initiated ebb shoal attachment to the barriers on either side of a non migrating inlet that experienced loss of tidal prism this shoal attachment was the main factor for the increase in total barrier area of ria formosa during the 60 years of analysis barrier growth after 2005 was slower which could indicate that the system is reaching morphodynamic stability

mineralogical analysis of the oppia quadrangle of asteroid 4 vesta evidence for occurrence of moderate reflectance hydrated minerals abstract quadrangle av 10 oppia is one of five quadrangles that cover the equatorial region of asteroid 4 vesta this quadrangle is notable for the broad spectrally distinct ejecta that extend south of the oppia crater these ejecta exhibit the steepest reddest visible spectral slope observed across the asteroid and have distinct color properties as seen in multispectral composite images compared to previous works that focused on the composition and nature of unusual orange ejecta found on vesta here we take into account a broader area that includes several features of interest with an emphasis on mineralogy as inferred from data obtained by dawn s visible infrared mapping spectrometer vir our analysis shows that the older northern and northeastern part of av 10 is dominated by howardite like material while the younger southwestern part including oppia and its ejecta blanket has a markedly eucritic mineralogy the association of the mineralogical information with the geologic and topographic contexts allows for the establishment of relationships between the age of the main formations observed in this quadrangle and their composition a major point of interest in the oppia quadrangle is the spectral signature of hydrous material seen at the local scale this material can be mapped by using high resolution vir data combined with multispectral image products from the dawn framing camera fc so as to enable a clear correlation with specific geologic features hydrated mineral phases studied previously on vesta generally correlate with low albedo material delivered by carbonaceous asteroids however our analysis shows that the strongest oh signature in av 10 is found in a unit west of oppia previously mapped as light mantle material and showing moderate reflectance and a red visible slope with the available data we cannot yet assess the presence of water in this material however we offer a possible explanation for its origin

multiscale phenomena in the tropical atmosphere over the western pacific abstract multiscale variabilities in the atmosphere over the tropical western pacific during the 1979 northern hemisphere winter are studied with an aim at identifying possible interactions between phenomena of different spatial and temporal scales based on the convection index information derived from satellite measurements two intra seasonal oscillations isos are identified within the equatorial belt between 0 and 10 s in the analyzed period the two isos accompanied by both rotational and divergent circulations propagate eastward from the indian ocean to the western pacific over the warm pool in the western pacific the isos develop into quasi stationary systems with an enhanced rotational circulation characterized by a strong westerly jet in the lower troposphere the isos appear to interact with a number of regional and synoptic scale phenomena in the maritime continent and western pacific region for example the onset of the monsoon coincides with the arrival of the first iso at northern a

active break cycles diagnosis of the intraseasonal variability of the asian summer monsoon in this study various diagnostics have been applied to daily observed outgoing longwave radiation olr and ecmwf reanalysis era products to provide a comprehensive description of the active break cycles associated with the asian summer monsoon and to address the differing behaviour of the two dominant time scales of intraseasonal variability 10 20 days and 30 60 days composite analysis of olr based on filtered daily all india rainfall air for the 40 day 30 60 days intraseasonal mode indicates that during active phases convection is significantly enhanced over the indian continent extending over the bay of bengal maritime continent and equatorial west pacific while convection is suppressed over the equatorial indian ocean and northwest tropical pacific resulting in a quadrapole structure over the asian monsoon domain in response to this heating pattern the large scale hadley lateral and the two east west transverse tropical circulations are enhanced there is also a significant impact on the extra tropical circulation through excitation and propagation of rossby waves in contrast the 15 day mode is more regional to the monsoon domain and has a prominent east west orientation in convection only the local hadley circulation over the monsoon region is modulated by this mode the evolution of these two modes as revealed by pop principal oscillation pattern analysis shows that the 40 day mode originates over the equatorial indian ocean once formed it has poleward propagation on either side of the equator and eastward propagation into the equatorial west pacific from the equatorial west pacific northward propagation over the west pacific and westward propagation into the indian longitudes are prominent the propagative features are complex and interactive and are responsible for the quadrapole structure in convection seen from the composites the interannual variability assessed from the pop coefficient time series indicates that the 40 day mode is strong during the onset phase of the monsoon in all the years but systematic propagation over the entire season depends crucially on the activity of the oceanic tcz tropical convergence zone the pop analysis of the 15 day mode indicates that this event originates over the equatorial west pacific associated with westward propagating rossby waves amplifies over the northwest tropical pacific and modulates both the continental and oceanic tczs over indian longitudes simultaneously this mode is pronounced during the established phase of the monsoon due to the complexity in the propagational features of both the intraseasonal modes it is concluded that understanding the subseasonal variability of one regional component of the asian summer monsoon asm requires understanding the entire asm system

modulation of eastern north pacific hurricanes by the madden julian oscillation abstract hurricane and tropical storm statistics verify the modulation of eastern pacific tropical systems by the madden julian oscillation mjo as hypothesized by maloney and hartmann over twice as many named tropical systems hurricanes and tropical storms accompany equatorial 850 mb westerly anomalies than accompany equatorial easterly anomalies and the systems that do exist are stronger hurricanes are over four times more numerous during westerly phases of the mjo than during easterly phases the current study constructs a composite life cycle of the mjo during may november 1979 95 using an index based on the 850 mb equatorial zonal wind equatorial kelvin waves propagating eastward from convective regions of the western pacific ocean alter dynamical conditions over the eastern pacific ocean westerly easterly equatorial 850 mb wind anomalies are accompanied by enhanced suppressed convection over the eastern pacific hurricane region convection locally amplifies the wind anomalies over the ea

intraseasonal variability of the low level jet stream of the asian summer monsoon abstract the strong cross equatorial low level jet stream llj with its core around 850 hpa of the asian summer monsoon june september is found to have large intraseasonal variability during the monsoon onset over kerala india and during break monsoon periods when the convective heating of the atmosphere is over the low latitudes of the indian ocean the axis of the llj is oriented southeastward over the eastern arabian sea and it flows east between sri lanka and the equator and there is no llj through peninsular india this affects the transport of moisture produced over the indian ocean to peninsular india and the bay of bengal in contrast during active monsoon periods when there is an east west band of strong convective heating in the latitudes 10 20 n from about longitude 70 to about 120 e the llj axis passes from the central arabian sea eastward through peninsular india and it provides moisture for the increased convection in the bay of bengal and for the monsoon depressions forming there

detections and geologic context of local enrichments in olivine on vesta with vir dawn data the magmatism characterizing the early history of the asteroid vesta has long been investigated with the mafic and ultramafic meteorites howardite eucrite and diogenite hed the lack of geologic context for the meteorites however has limited its understanding here we use the visible to near ir vir orbital observations of vesta s surface to detect relative enrichments in olivine and to study the associated geologic features because the near ir signature of olivine on vesta s surface is subtle relative to the widespread pyroxene absorption bands a method was developed to distinguish olivine enrichments from admixture of pyroxenes with high fe2 m1 dark material and potential fe bearing glass relative enrichment of olivine 50 60 vol is found in 2 5 km wide morphologically fresh areas our global survey reveals a dozen of these areas clustering in the eastern hemisphere of vesta the hemispherical coincidence with a widespread low enrichment in diogenite like pyroxene suggests the presence of a distinct compositional terrain on the central mound of the rheasilvia impact basin no olivine enrichment was found suggesting the absence of an olivine dominated mantle above the basin s excavation depth or alternatively a low amount of olivine homogeneously mixed with diogenite like pyroxenes rare olivine enriched areas in close proximity to diogenite like pyroxene are found as part of material ejected by the rheasilvia impact such cooccurrence is reminiscent of local ultramafic lithologies within the crust the possible formation of such lithologies on vesta is supported by some hed meteorites dominated by olivine and orthopyroxene

delayed onset of the 2002 indian monsoon 1 we show that there is a set of dynamical predictors which facilitate forecasting of a delayed monsoon onset the main dynamical contributor is the early may propagation of the bogus onset intraseasonal oscillation which triggers a set of events precluding the climatological monsoon onset we analyze in detail the 2002 monsoon onset and show that it followed a pattern described in our previous study we notice that the 2003 monsoon onset followed very similar pattern and was delayed

the post glacial landscape evolution of the north german basin morphology neotectonics and crustal deformation the recent evolution of the north german basin ngb which is presently a low seismic area was partly affected by glacial loading and unloading of the ice masses major stresses acting within the ngb are induced by the north atlantic ridge push the ongoing alpine collision and the post glacial rebound of fennoscandia present day horizontal stresses within the ngb are directed generally nw se but fan and bend north of 52 n towards nne major basement faults are directed nw se minor faults ne sw and nne ssw and are clearly detectable in geomorphological and satellite lineaments furthermore the drainage pattern and the distribution of lakes in northern germany follow exactly block boundaries and hence mark zones of present day subsidence the understanding of the post glacial morphology and reactivation of faults requires a view into the very heterogeneous crust and upper mantle below the ngb the re adjustment of the individual fault blocks during post glacial relaxation of the lithosphere leads to differential crust dependent uplift and probably to the formation of urstrom valleys the urstrom valleys and terminal moraines in northern germany appear to parallel the major tectonic lineaments and lithospheric block boundaries the lithospheric memory is expressed in the post glacial landscape evolution of the ngb

mineralogical and spectral analysis of vesta s gegania and lucaria quadrangles and comparative analysis of their key features abstract this work is aimed at developing and interpreting infrared albedo pyroxene and oh band depths and pyroxene band center maps of vesta s gegania and lucaria quadrangles obtained from data provided by the visible and infrared vir mapper spectrometer on board nasa s dawn spacecraft the gegania and lucaria quadrangles span latitudes from 22 s to 22 n and longitudes from 0 e to 144 e the mineralogical and spectral maps identify two large scale units on this area of vesta which extend eastwards and westward of about 60 e respectively the two regions are not associated to large scale geological units which have a latitudinal distribution rather than longitudinal but are defined by different contents of carbonaceous chondrites cc the eastern region poor in ccs is brighter and oh depleted whereas the western one rich in ccs is darker and oh enriched a detailed analysis of the small scale units in these quadrangles is also performed almost all the units show the typical correspondence between high albedo deep pyroxene bands short band centers and absence of oh and vice versa only a few exceptions occur such as the ejecta from the aelia crater where dark and bright materials are intimately mixed the most characteristic features of these quadrangles are the equatorial troughs and the lucaria tholus the equatorial troughs consist of graben i e a depression limited by two conjugate faults the graben do not present their own spectral signatures but spectral parameters similar to their surroundings in agreement to their structural origin this is observed also in graben outside the gegania and lucaria quadrangles however it is possible to observe other structural features such as tectonic grooves characterized by a changing composition and hence an albedo variation this result is confirmed not only by mineralogical maps of vesta but also by analyzing the virtis rosetta observations of lutetia the albedo change is instead a typical behavior of geomorphic grooves finally ridges are characterized by a bluer color and in some cases shorter band centers than their surroundings suggesting that they are composed of fresher materials we also performed a comparative analysis between the three tholi of vesta i e lucaria which gives the name to its quadrangle aricia in the marcia quadrangle and brumalia numisia quadrangle whereas brumalia tholus is a young magmatic intrusion the absence of diogenites the low albedo and the orientation of aricia and lucaria tholi suggest that they are older features which are covered by dark materials and therefore experienced a different geological history than brumalia

relation of the spectroscopic reflectance of olivine to mineral chemistry and some remote sensing implications using high resolution visible and near infrared diffuse spectral reflectance we have systematically investigated apparent wavelength shifts as a function of mineral chemistry in the fe mg olivine series from fo11 to fo91 the study also shows that trace amounts of nickel can be spectrally detected in the olivine structure we show that significant compositional information can only be extracted at relatively high resolution because the overall spectral characteristics of the olivines change only subtly as a function of the fe mg ratio significant spectral variation as a function of grain size is also demonstrated adding a further complication to the interpretation of remotely sensed data from olivine rich surfaces this laboratory study is expected to aid in the interpretation of remotely sensed data from both terrestrial and extraterrestrial bodies terrestrial applications may include the recognition of ultramafic ultrabasic and basaltic terrains which in themselves may have mineral potential among extraterrestrial applications the asteroids are obvious candidates for further examination if instrumentation can provide the necessary wavelength coverage resolution and signal to noise ratio so that spectra can be compared to those laboratory data discussed here some permutations of fe mg ni relations in olivines are discussed as they apply to the interpretation of asteroid surfaces and other extraterrestrial bodies

a magma ocean on vesta core formation and petrogenesis of eucrites and diogenites abstract available evidence strongly suggests that the hed howardite eucrite diogenite meteorites are samples of asteroid 4 vesta abundances of the moderately siderophile elements ni co mo w and p in the hed mantle indicate that the parent body may have been completely molten during its early history during cooling of a chondritic composition magma ocean equilibrium crystallization is fostered by the suspension of crystals in a convecting magma ocean until the crystal fraction reaches a critical value near 0 80 when the convective system freezes and melts segregate from crystals by gravitational forces the extruded liquids are similar in composition to main group and stannern trend eucrites and the last pyroxenes to precipitate out of this ocean before convective lockup span the compositional range of the diogenites subsequent fractional crystallization of a main group eucrite liquid which has been isolated as a body of magma produces the nuevo laredo trend and the cumulate eucrites the predicted cumulate mineral compositions are in close agreement with phase compositions analyzed in the cumulate eucrites thus eucrites and diogenites are shown to have formed as part of a simple and continuous crystallization sequence starting with a magma ocean environment on an asteroidal size parent body that is consistent with vesta

observations of eastward propagation of atmospheric intraseasonal oscillations from the pacific to the atlantic received 19 april 2010 revised 20 september 2010 accepted 29 september 2010 published 19 january 2011 1 significant 40 60 day intraseasonal variability in surface winds sea level and thermocline depth were observed in the tropical atlantic during the atlantic nino year of 2002 satellite derived quikscat winds and noaa outgoing longwave radiation olr measurements for the period of 2000 2006 together with reanalysis of winds from a longer record are analyzed to understand the sources of this 40 60 day wind variability and the global propagation of the madden julian oscillation mjo surface signatures the results demonstrate that the mjo propagated eastward from the indo pacific ocean to the atlantic during winter and spring of 2002 causing 40 60 day wind variations in the equatorial atlantic the isthmus of panama appears to be a dominant pathway for these surface wind anomalies to propagate into the atlantic where they can produce important climate impacts this result is consistent with previous work that has demonstrated a strong mjo influence on the north american monsoon nam region and complements other work demonstrating the propagation of intraseasonal wind anomalies and accompanying sea level pressure signals associated with dry equatorial kelvin waves that reach the caribbean through the panama gap the mjo is also shown to have a large influence on the subtropical atlantic ocean seasonality of the mjo impact on atlantic surface winds is investigated using data from an extended record and the most direct influence is found to be during boreal winter and spring with a delayed influence during summer and fall

the origin of eucrites diogenites and olivine diogenites magma ocean crystallization and shallow magma chamber processes on vesta the asteroid 4 vesta is one of the very few heavenly bodies to have been linked to samples on earth the howardite eucrite diogenite hed meteorite suite this large and diverse suite of meteorites provides a detailed picture of vesta s igneous and postigneous history we have used the range of igneous rock types and compositions in the hed suite to test a series of chemical models for solidification processes following peak melting magma ocean conditions on vesta fractional crystallization cannot have been a dominant early process in the magma ocean because it leads to excessive fe enrichment in the melt models that are dominated by equilibrium crystallization cannot produce orthopyroxene cumulates diogenites our best models invoke 60 70 equilibrium crystallization of a magma ocean followed by continuous extraction of the residual melt into shallow magma chambers fractional crystallization in these magma chambers combined with continuous or periodic addition of more melt from the slowly compacting crystal mush magmatic recharge can produce all of the igneous hed lithologies noncumulate and cumulate eucrites diogenites dunites harzburgites and olivine diogenites magmatic recharge can also explain the narrow range in eucrite compositions and the variability of incompatible trace element concentrations in diogenites we predict an internal structure for vesta that permits excavation of the heds during the formation of the rheasilvia basin while remaining consistent with observations from the dawn mission and most impact models

on the tropical atmospheric signature of el nino abstractthe linear atmospheric signature of enso obtained by regressing fields of geopotential height z wind vertical velocity and rainfall upon the nino 3 4 sea surface temperature sst index is partitioned into zonally symmetric and eddy components the zonally symmetric component is thermally forced by the narrowing and intensification of the zonally averaged equatorial rain belt during el nino and mechanically forced by the weakening of the upper tropospheric equatorial stationary waves and their associated flux of wave activity the eddy component of the enso signature is decomposed into barotropic bt and baroclinic bc contributions the latter into first and second modal structures bc1 and bc2 separable functions of space x y and pressure p using eigenvector analysis bc1 exhibits a nearly equatorially symmetric planetary wave structure comprising three dumbbell shaped features suggestive of equatorial rossby waves with out of phase wind and geopotential height perturbations in the

micro tidal coastal reed beds hydro morphological insights and observations on wave transformation from the southern baltic sea abstract this paper investigates the hydro morphological controls on incident wind generated waves at and the transformation of such waves within two phragmites australis reed beds in the southern baltic sea meteorological conditions in combination with geomorphological controls result over short 0 5 hz was preferentially reduced at the reed margin confirming the theoretical wave frequency dependence of bottom friction the possibility of physiological adaptation differences in reed stem diameter to water depth and wave exposure differences is discussed the results have implications for the possible impact of environmental changes both acute e g storm surges or chronic e g sea level rise in character and for the appropriate management of reed bed sites and delivery of ecological goods and services

the boreal summer intraseasonal oscillation relationship between northward and eastward movement of convection the summertime intraseasonal oscillation iso is an important component of the south asian monsoon lagged regressions of intraseasonally filtered 25 80 days outgoing longwave radiation olr reveal that centers of convection move both northward and eastward from the central equatorial indian ocean subsequent to the initiation of an iso eastward movement of convection is also seen at indian subcontinent latitudes 10 8 208n based on the regression results the summertime iso convection signal appears as a band tilting northwestward with latitude and stretching from the equator to about 208n viewed along any meridian convection appears to propagate northward while equatorial convection propagates to the east to examine the robustness of the connection between eastward and northward movement individual isos are categorized and composited relative to the strength of the large scale eastward component of convection in the central equatorial indian ocean it is found that the majority of isos that exhibit northward movement onto the indian subcontinent 42 out of 54 isos or 78 also exhibit eastward movement into the western pacific ocean it is also found that when convection in the central indian ocean is not followed within 10 20 days by convection in the western pacific ocean 12 out of 54 isos or 22 the independent northward movement of convection in the indian ocean region is somewhat stunted the link between the eastward and northward movement of convection is consistent with an interpretation of the summertime iso in terms of propagating equatorial modes the northward moving portion of convection is forced by surface frictional convergence into the low pressure center of the rossby cell that is excited by equatorial iso convection a similar convergence pattern is seen for the northern winter iso but it does not generate poleward movement due to relatively cool ssts underlying the surface convergence

distinctive space weathering on vesta from regolith mixing processes whereas space weathering of some airless bodies such as the moon occurs through the accumulation on regolith of nanophase metallic particles spectroscopic data show that space weathering of the asteroid vesta occurs through the small scale mixing of diverse surface components which gradually generates locally homogenized upper regolith between 16 july 2011 and 5 september 2012 nasa s space probe dawn was orbiting vesta a protoplanet thought to have survived virtually intact since an early phase of solar system formation in this issue of nature two groups report on the encounter carle pieters and co workers find that space weathering on vesta has followed a different course from that observed on the moon and on itokawa the asteroid sampled in an earth return mission on vesta weathering involved fine scale regolith soil mixing that has removed clear traces of recent impact deposits there are no signs of the nanophase metallic particle deposits seen on the moon and itokawa thomas mccord and co authors describe two main types of material on vesta s surface bright and dark the bright material may be uncontaminated indigenous vesta basaltic soil with the darker material derived from low albedo impactors dawn has now moved on and is due to rendezvous with the protoplanet ceres in february 2015 the surface of the asteroid vesta has prominent near infrared absorption bands characteristic of a range of pyroxenes confirming a direct link to the basaltic howardite eucrite diogenite class of meteorites1 2 3 processes active in the space environment produce space weathering products that substantially weaken or mask such diagnostic absorption on airless bodies observed elsewhere4 5 and it has long been a mystery why vesta s absorption bands are so strong analyses of soil samples from both the moon6 and the asteroid itokawa7 determined that nanophase metallic particles commonly nanophase iron accumulate on the rims of regolith grains with time accounting for an observed optical degradation these nanophase particles believed to be related to solar wind and micrometeoroid bombardment processes leave unique spectroscopic signatures that can be measured remotely8 9 10 but require sufficient spatial resolution to discern the geologic context and history of the surface which has not been achieved for vesta until now here we report that vesta shows its own form of space weathering which is quite different from that of other airless bodies visited no evidence is detected on vesta for accumulation of lunar like nanophase iron on regolith particles even though distinct material exposed at several fresh craters becomes gradually masked and fades into the background as the craters age instead spectroscopic data reveal that on vesta a locally homogenized upper regolith is generated with time through small scale mixing of diverse surface components

composition of the rheasilvia basin a window into vesta s interior 1 the estimated excavation depth of the huge rheasilvia impact basin is nearly twice the likely thickness of the vestan basaltic crust so the mantle should be exposed spectral mapping by the dawn spacecraft reveals orthopyroxene rich materials similar to diogenite meteorites in the deepest parts of the basin and within its walls significant amounts of olivine are predicted for the mantles of bulk chondritic bodies like vesta and its occurrence is demonstrated by some diogenites that are harzburgite and dunite however olivine has so far escaped detection by dawn s instruments spectral detection of olivine in the presence of orthopyroxene is difficult in samples with 25 olivine and olivine in rheasilvia might have been diluted during impact mixing or covered by the collapse of basin walls the distribution of diogenite inferred from its exposures in and around rheasilvia provides a geologic context for the formation of these meteorites but does not clearly distinguish between a magmatic cumulate versus partial melting restite origin for diogenites the former is favored by geochemical arguments and crystallization in either a magma ocean or multiple plutons emplaced near the crust mantle boundary is permitted by dawn observations

kelvin waves and tropical cyclogenesis a global survey abstractconvectively coupled atmospheric kelvin waves are among the most prominent sources of synoptic scale rainfall variability in the tropics but large uncertainties surround their role in tropical cyclogenesis this study identifies the modulation of tropical cyclones relative to the passage of a kelvin wave s peak rainfall i e its crest in each basin tropical cyclogenesis is generally inhibited for 3 days before the crest and enhanced for 3 days afterward composites of storms forming in the most favorable lags illustrate the dynamical impacts of the waves in most basins the tropical cyclone actually forms during the convectively suppressed phase of the wave the 850 hpa equatorial westerly anomalies provide the cyclonic vorticity for the nascent storm and 200 hpa easterly anomalies enhance the outflow the wind anomalies persist at both levels longer than the kelvin wave s period and are often related to the madden julian oscillation mjo the onset of these wind anomalies occurs with the

color and albedo heterogeneity of vesta from dawn multispectral images 0 44 to 0 98 m of asteroid 4 vesta obtained by the dawn framing cameras reveal global color variations that uncover and help understand the north south hemispherical dichotomy the signature of deep lithologies excavated during the formation of the rheasilvia basin on the south pole has been preserved on the surface color variations band depth spectral slope and eucrite diogenite abundance clearly correlate with distinct compositional units vesta displays the greatest variation of geometric albedo 0 10 to 0 67 of any asteroid yet observed four distinct color units are recognized that chronicle processes including impact excavation mass wasting and space weathering that shaped the asteroid s surface vesta s color and photometric diversity are indicative of its status as a preserved differentiated protoplanet

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

the shoreline displacement curve of rugen island southern baltic sea abstract rugen island is situated in north east germany at the southern baltic sea coast geological stratigraphical and palaeoecological evidence collected from the schaabe spit in northeast rugen include 167 cores and 46 radiocarbon dates leading to a local shoreline displacement curve which is compared and discussed with morner s eustatic curve of northwest europe and tooley s shoreline displacement curve of northwest england corresponding to these curves the holocene sea level rise occurred in phases on rugen island the undulations found fit temporally well there is a close correlation between the shoreline displacement curves of the lytham area in northwest england and rugen island during the boreal and the atlanticum compared with morner s eustatic curve rugen island was uplifted between about 7000 bp and 5000 bp in a range of 6 m since that time stable conditions or slightly subsidence are presumed on rugen island

a model for the boreal summer intraseasonal oscillation abstract the tropical intraseasonal oscillation iso exhibits pronounced seasonality the boreal summer iso is more complex than its winter counterpart due to the coexistence of equatorial eastward off equatorial westward and northward propagating low frequency modes and their interactions based on observational evidence and results obtained from numerical experiments a mechanism is proposed for the boreal summer iso in which the northern hemisphere summer monsoon nhsm circulation and moist static energy distribution play essential roles with a climatological july mean basic state the life cycle of model low frequency waves consists of four processes an equatorial eastward propagation of a coupled kelvin rossby wave packet an emanation of moist rossby waves in the western pacific a westward propagation and amplification of the rossby waves in south asian monsoon regions and a reinitiation of the equatorial disturbances over the central indian ocean the life cycle spans about one month and p

influence of the madden julian oscillation and intraseasonal waves on surface wind and convection of the tropical atlantic ocean abstractatmospheric intraseasonal variability in the tropical atlantic is analyzed using satellite winds outgoing longwave radiation olr and reanalysis products during 2000 08 the analyses focus on assessing the effects of dominant intraseasonal atmospheric convective processes the madden julian oscillation mjo and rossby waves on surface wind and convection of the tropical atlantic ocean and african monsoon area the results show that contribution from each process varies in different regions in general the mjo events dominate the westward propagating rossby waves in affecting strong convection in the african monsoon region the rossby waves however have larger contributions to convection in the western atlantic ocean both the westward and eastward propagating signals contribute approximately equally in the central atlantic basin the effects of intraseasonal signals have evident seasonality both convection amplitude and the number of strong convective events associated with the mjo are l

primary and successive events in the madden julian oscillation conventional analyses of the mjo tend to produce a repeating cycle such that any particular feature cannot be unambiguously attributed to the current or previous event we take advantage of the sporadic nature of the mjo and classify each observed madden julian mj event as either primary with no immediately preceding mj event or successive which does immediately follow a preceding event 40 of mj events are primary events precursor features of the primary events can be unambiguously attributed to that event a suppressed convective anomaly grows and decays in situ over the indian ocean prior to the start of most primary mj events an associated mid tropospheric temperature anomaly destabilises the atmosphere leading to the generation of the active mj event hence primary mj events appear to be thermodynamically triggered by a previous dry period although stochastic forcing may also be important other theories predict that boundary layer convergence humidity propagation of dynamical structures around the equator sea surface temperatures and lateral forcing by extratropical transients may all be important in triggering an event although precursor signals from these mechanisms are diagnosed from reanalysis and satellite observational data in the successive mj events they are all absent in the primary mj events hence it appears that these apparent precursor signals are part of the mjo once it is established but do not play a role in the spontaneous generation of the mjo the most frequent starting location of the primary events is the indian ocean but over half of them start elsewhere from the maritime continent to the western pacific copyright 2008 royal meteorological society

relative chronology of crust formation on asteroid vesta insights from the geochemistry of diogenites abstract the eucrites and diogenites are meteorites that probably originate from asteroid 4 vesta the upper part of the crust of this body is certainly composed of eucrites which are basaltic or gabbroic rocks diogenites are ultramafic cumulates whose relationships with eucritic lithologies are unknown here we show that the orthopyroxenes of some diogenites display very deep negative eu anomalies eu eu close to 0 1 or lower the contamination of the parental magmas of diogenites by melts derived by partial melting of the eucritic crust can satisfactorily explain the range of the eu anomalies displayed by diogenites thus these anomalies are the first firm indication that parental melts of diogenites have intruded the eucritic crust and consequently are younger than eucrites

a numerical approach for approximating the historical morphology of wave dominated coasts a case study of the pomeranian bight southern baltic sea abstract comparison between historical maps from the 1900s 1980s and a modern map from the 2000s of the pomeranian bight at the southern baltic sea indicates that a major part of the coastline has been suffering continuous erosion this also holds for a major part of other coasts on a global scale quantifying coastal geomorphological changes on a decadal to centennial temporal scale thus needs to be intensified for coastal protection activities and integrated coastal zone management this study applies an estimation of sediment mass balance including the investigation of sediment source to sink transport in the case of absent historical survey data a numerical approach namely the dynamic equilibrium shore model desm is developed to approximate the historical morphology and to estimate sediment budget of wave dominated coasts based on the information of historical coastline configuration derived from maps a high resolution modern digital elevation model dem and relative sea level change the basic concept of the model is a dynamic equilibrium of the coastal cross shore profiles adapting to sediment mass balancing of a semi enclosed coastal area in which the unknown parameters of the cross shore profile shapes are calculated by numerical iterations the model is applied at the pomeranian bight in order to validate its capability in reflecting the pattern of bed level change and estimating sediment mass volume two tests of the model are conducted in approximating historical dems in 1980s and ca 1900 the changes of approximated dems from past to present are then respectively compared with the ones derived from a nautical sea chart in 1980s and the ones produced by a complex morphodynamic model that uses the approximated dem at ca 1900 as a starting point to hindcast the coastal morphological evolution of the research area the deposition erosion patterns along the coastline are consistent in both comparisons the pre conditions and limitations of the model are discussed in detail the model proposed here can serve as a useful tool for coastal morphological studies and potential applications for the future projection of coastal morphogenesis

structure genesis and scale selection of the tropical quasi biweekly mode the quasi biweekly mode qbm and the 30 60 day mode are two major intraseasonal oscillations isos in the tropics the qbm is known to have a major influence in determining the active and break conditions of the indian monsoon during the northern summer a westward propagating equatorial rossby wave with quasi biweekly period influences the australian monsoon during the northern winter universality between the summer and winter qbm is established through analysis of daily circulation and convection data for 10 years it is shown that the mean spatial structure of the qbm in circulation and convection resembles that of a gravest meridional mode equatorial rossby wave with wavelength of about 6000 km and westward phase speed of approximately 4 5 m s 1 however the maximum zonal wind occurs at around 5 n 5 s during the northern summer winter the wave structure appears to be translated northward southward by about 5 during the northern summer winter the relationship between outgoing long wave radiation and circulation data indicates that the mode is driven unstable by coupling with moist convection similarity in temporal and spatial characteristics of the mode during the two seasons leads us to propose that the same mechanism governs the genesis and scale selection of the mode in both the seasons an acceptable mechanism for genesis and scale selection of the qbm has been lacking in the present study a mechanism for genesis and scale selection of the observed qbm is proposed a simple 2 layer model that includes a steady ekman boundary layer bl formulation incorporating effect of entrainment mixing is constructed for the convectively coupled equatorial waves without influence of the background mean flow moist feedback in the presence of frictional bl convergence drives the gravest meridional mode equatorial rossby wave unstable with observed wavelength and period but with zonal winds symmetric about the equator potential temperature perturbation associated with the rossby wave is in phase with relative vorticity perturbation at low level the bl drives moisture convergence in phase with the relative vorticity at the top of the bl release of latent heat associated with the bl convergence enhances the potential temperature leading to a positive feedback the mean flow over the indian ocean and western pacific at low levels is such that the zero ambient absolute vorticity or the dynamic equator shifts to around 5 n 5 s during summer winter and results in a shift of the unstable rossby waves towards the north south by about 5 the resulting structure of the unstable rossby mode resembles the observed structure of the biweekly mode it is shown that neither evaporation wind feedback nor vertical shear of the mean flow is crucial for the existence of the mode however these processes marginally modify the growth rate and make the structure of the unstable wave more realistic