tidal modeling of an ancient tide dominated seaway part 1 model validation and application to global early cretaceous aptian tides abstract the utility of deep time global paleotidal modeling is evaluated with a series of modeling experiments focused on the early cretaceous aptian the results from a series of paleobathymetry sensitivity experiments indicate that despite paleogeographic and paleobathymetric uncertainty appropriate use of global paleotidal models complements and enhances stratigraphic and sedimentological methods before being applied to global paleotidal modeling the imperial college ocean model icom is validated for the computation of modern global tides the icom results only deviate slightly from a state of the art published model and were achieved with considerably less computational expense and without data assimilation the results from global paleotidal modeling of the early cretaceous aptian were assessed by comparison with the published geological record icom predicts high mesotidal to macrotidal ranges on the arabian platform around india especially to the north and west along the pacific coast between north and south america northeast of australia and around southeast asia the model predicts low microtidal ranges in the proto south atlantic ocean and weddell sea a further validation test assessed the ability of the model to predict the dominant tidal constituents diurnal or semidiurnal in the aptian lower greensand seaway of southeastern england and northern france during the aptian this region was connected to the boreal proto atlantic and neotethys oceans and now preserves superbly documented tidal deposits the model predicts low microtidal ranges in the proto central atlantic ocean and boreal ocean suggesting that they had little impact on tides in the lower greensand seaway higher tidal amplitudes especially of diurnal once daily tides are predicted in the northwestern neotethys ocean suggesting that this ocean was an important source of tidal energy to the lower greensand seaway sensitivity tests to paleogeographic and paleobathymetric uncertainty indicate that the model predictions are robust the prediction of predominantly diurnal tides is supported by published analyses of large dune scale deposits in the lower greensand of southeast england

circulation and transport of water along the western weddell sea margin ocean current temperature and salinity data obtained from the western weddell sea during the austral winter 1992 u s russian drifting ice station experiment ice station weddell 1 isw 1 are used to describe water circulation and transport surface to bottom baroclinic currents were computed by applying the geostrophic approximation to derived density data these were corrected using current measurements obtained from drifting current meter arrays and the resulting total currents were vertically integrated to obtain volume transports transport was found to be northward in the region which encompassed the western boundary current of the cyclonic weddell sea gyre this northward transport increased from south to north by more than a factor of 2 from about 12 106m3 s 1 in the southwestern weddell to about 28 106m3s 1 farther north the increase in northward transport was compensated for by westward flow from the interior of the gyre into the western boundary region about 5 6 106m3s 1 of the northward transport was contained in a 300 500 m thick bottom layer of cold water this layer whose transport increased by about 1 106 m3 s 1 from south to north was identifiable by its water mass characteristics as weddell sea bottom water originating on the southwestern and western shelf regions its north flowing volume was consistent with past estimates of a 1 5 2 106 m3 s 1 production rate coupled with a 300 400 transport increase due to entrainment during downslope flow from the shelves to the deep basin the maximum northernmost northward transport less the bottom water transport is consistent with previous estimates for wind driven transport in the weddell gyre provided that bottom friction and the sea ice influence on wind forcing are taken into consideration

circulation mixing and production of antarctic bottom water abstract the antarctic source of bottom water to the abyssal layer of the world ocean is examined as well as its large scale flow pattern and ultimate entrainment rate into the deep water above we make use of the available high quality station data in the southern ocean to construct bottom maps of neutral density and mean property maps including chlorofluorocarbon cfc for the abyssal layer underneath a selected neutral density surface the maximum density at the sill depth of drake passage is used to distinguish between the voluminous deep water mass that is a continuous component of the antarctic circumpolar current from the relatively denser bottom water originated along the antarctic continental margins based on water density antarctic bottom water aabw is defined here generically to include all volumes of non circumpolar water of antarctic origin over the shelf regime multiple localized sources of specific aabw types contribute to the abyssal layer of the adjacent antarctic basins characteristics of these dense bottom waters reflect closely those observed on the parent shelf water mass spreading paths of newly formed deep and bottom waters over the slope regime and their subsequent oceanic circulation patterns are analyzed on the basis of global property maps for the aabw layer interior mixing and interbasin exchanges of aabw are deduced from mean characteristic curves following the southern streamline of the antarctic circumpolar current outflow and mixing of aabw from the weddell sea to the argentine basin is depicted using density and cfc distributions of two zonal hydrographic lines recirculation and mixing of deep and bottom waters within the weddell gyre are also detailed using a meridional section along the greenwich meridian the strength of all localized sources of aabw combined is estimated by two independent approaches an estimate of the total production rate of aabw is calculated based on the oceanic cfc budget for the aabw layer offshore of the 2500 m isobath the sum of all downslope inputs of well ventilated bottom water types underneath the top isopycnal must account for the measured cfc content in the bottom layer the resulting total aabw production rate is about 8 sv which is a conservative figure that neglects the loss of cfc bearing waters across the top isopycnal in recent years whereas about 9 5 sv is calculated assuming a well mixed bottom layer making use of their transient nature cfc distributions at the top of the aabw layer indicate that more direct and rapid entrainment of cfc rich bottom waters below occurs over localized areas with relatively strong upwelling rates and enhanced vertical mixing a second more ad hoc but independent oceanic mass budget of the bottom layer is also constructed a typical basin wide rate of deep upwelling of 3 10 7 m s 1 requires 10 sv 1 sv 106 m3 s 1 of newly formed aabw to sink down the slope around antarctica we have also formulated a spatial distribution of deep upwelling on the isopycnal at the top of the aabw it is expressed as a combination of wind topographic and turbulent components which in turn are functions of the isopycnal depth bottom depth and bottom layer thickness this non uniform upwelling field yields about 12 sv of aabw exported across the top isopycnal fortuitously the overall average of upward speed at the top isopycnal 3 7 10 7 m s 1 compares well with previous estimates of deep upwelling in the northern basins a series of likely sites for strong vertical entrainment of aabw are clearly identified in the modeled distribution of deep upwelling consonant with the observed cfc distributions on the top isopycnal altogether regions with relatively high upwelling rates 5 10 7 m s 1 occupy only a quarter of the total areal extent of the top isopycnal but they account for as much as 45 of the total vertical transport

formation and export of dense shelf water from the adelie depression east antarctica 1 coastal polynyas in the adelie depression are an important source of antarctic bottom water to the australian antarctic basin we present time series april 1998 to may 1999 and august 1999 to february 2000 of data from temperature salinity sensors in both the adelie depression and the known outflow region of the adelie sill to describe the annual cycle of shelf water densities from april through september salinification beneath the polynya produces dense shelf waters during september october shelf water densities in the depression peak at 27 94 kg m 3 and the cooling and freshening signature of ice shelf water is observed north of buchanan bay in november december shelf water densities decrease as intrusions of warm and relatively fresh modified circumpolar deep water enter east of the adelie sill from january march the surface layer is conditioned by the cooling of the atmosphere which overturns the upper water column at the adelie sill observed daily mean currents were approximately 10 cm s 1 with intense instantaneous currents greater than 50 cm s 1 at the sill depth using an idealized outflow region with a rectangular cross sectional area 6 106 m2 we present the first estimates of shelf water export by potential density class assuming shelf water with a minimum density of 27 88 kg m 3 has sufficient negative buoyancy for downslope mixing and a fourfold volume increase 1 3 mixing ratio from entrainment the dense shelf water export of 0 1 0 5 sv results in an annual average production of bottom water in this region of between 0 4 and 2 0 sv the wide range in bottom water estimate results from data limitations and a narrowing of this range requires further mooring observations

a comparison of measured and wind derived ekman transport at 11 n in the atlantic ocean abstract a comparison of measured and wind derived ageostrophic transport is presented from a zonal transect spanning the atlantic ocean along 11 n the transport per unit depth shows a striking surface maximum that decays to nearly zero at a depth of approximately 100 m we identify this flow in the upper 100 m as the ekman transport the sustained values of wind stress and the penetration depth of the ekman transport reported here are considerably greater than in previous observations which were made in conditions of light winds the transport of 12 0 5 5 106 m3 s 1 calculated from the difference of geostrophic shear and shear measured by an acoustic doppler current profiler is in good agreement with that estimated from the shipboard winds 8 8 1 9 106 m3 s 1 and from climatology 13 5 0 3 106 m3 s 1 qualitatively the horizontal distribution of the wind driven flow was best predicted by the shipboard winds the cumulative transport increased linearly over the western three fourths of t

late jurassic blueschist facies pebbles from the western carpathian orogenic wedge and paleostructural implications for western tethys evolution in spite of the absence of ophiolitic slices at the surface some traces of the lost tethys ocean are recorded along the pieniny klippen belt pkb a narrow decollement thrust system sutured at the transpressive boundary between the outer and inner carpathians the enigmatic precollisional evolution of western carpathians can be deciphered from some late albian to campanian flysch conglomerates which display chrome spinel grains ophiolitic detritus and pebbles of blueschist facies tholeiitic metabasalts yielding a 40ar 39ar plateau age of 155 4 0 6 ma other detrital components are represented by extrabasinal pebbles of limestones arc volcanics and igneous to metamorphic basement rocks from southern sources our results suggest a markedly northward extension of the sublongitudinal triassic vardar meliata ocean and its subduction since the late middle jurassic supposedly balanced westward by coeval spreading in the ligurian piedmont basin of the apennine western alpine tethys a lateral kinematic connection between these diachronous and roughly parallel tethys branches was provided on the north by a left lateral east west trending shear zone running from the swiss austrian penninic domain to the northern carpathians this reconstruction replaces the classic model of two paired north penninic and south penninic oceanic basins and eastern homologues with the brianconnais hochstegen and czorstin microcontinents in between the late jurassic early cretaceous evolution of the carpathian active margin was characterized by subduction metamorphism and accretion of a wide orogenic wedge in this time the shallowing to deeply subsiding basins inferred from facies analyses on the sedimentary units of the pkb were likely floored by individual sections of the growing wedge later some exhuming blueschist ophiolitic units of the wedge were uplifted to the surface and functioned in the albian campanian as an exotic ridge supplying clasts to the forearc basin finally the colliding wedge became a cryptic paleostructure when since the latest cretaceous it disappeared beneath the inner carpathian orogenic lid and was incorporated within the eastward moving infrastructure of the carpathian orocline

passive and active margin history of the northern tatricum western carpathians slovakia the tatricum an upper crustal thrust sheet of the central western carpathians comprises pre alpine crystalline basement and a late paleozoic mesozoic sedimentary cover the sedimentary record indicates gradual subsidence during the triassic early jurassic initial rifting a jurassic early cretaceous extensional tectonic regime with episodic rifting events and thermal subsidence periods and middle cretaceous overall flexural subsidence in front of the orogenic wedge prograding from the hinterland passive rifting led to the separation of the central carpathian realm from the north european platform a passive margin rimmed by peripheral half graben was formed along the northern tatric edge facing the vahic south penninic oceanic domain the passive versus active margin inversion occurred during the senonian when the vahic ocean began to be consumed southwards below the tatricum it is argued that passive to active margin conversion is an integral part of the general shortening polarity of the western carpathians during the mesozoic that lacks features of an independent wilson cycle an attempt is presented to explain all the crustal deformation by one principal driving force the south eastward slab pull generated by the subduction of the meliatic triassic jurassic tethys oceanic lithosphere followed by the subcrustal subduction of the continental mantle lithosphere

natural and human influence on loess gully catchment evolution a case study from lublin upland e poland abstract this paper presents the functioning of a gully system catchment in the loess area of the lublin upland eastern poland based on investigations of soil and sediment sequences filling the valley floors and correlative sediments on the alluvial fan at the valley outlet stages of the catchment s evolution are proposed from the meso holocene 8400 5100 bp followed by prehistorical and historical stages of human activity to modern times gully erosion varying erosional processes have been identified over a period of about 2800 years bp washing and sediment deposition on the alluvial fan at early stages followed by multi branched gully system development later on land use change of deforestation and agriculture led to dissection of gully edges by a system of badlands this study demonstrates the roll of the human factor as a shifting agent between dominant geomorphic processes in the same catchment area over a long period of time

factors controlling sediment yield from small intensively cultivated catchments in a temperate humid climate abstract data on sediment yield from 26 small cultivated catchments 10 10 000 ha in central belgium were collected based on sedimentation rates in small flood retention ponds area specific sediment yield varies from 0 4 to 20 6 t ha 1 year 1 for catchments ranging from 7 to 4873 ha various catchment properties were analysed in order to understand this large variation in sediment yield catchment area alone explains 64 of the observed variance in area specific sediment yield although no other parameter could explain more it is concluded that catchment area is not a valid parameter to link with sediment yield overall catchment geomorphology e g presented by the hypsometric integral is much more important in controlling sediment yield the lack of data however made this not very clear a multiple regression model including three morphological catchment properties is a valuable tool to predict total sediment yield t year 1 from catchments in central belgium this model has an efficiency of 0 81 furthermore it was concluded that the within catchment spatial distribution of parameters for instance slope steepness is very important but difficult to obtain one single representative value the use of spatially distributed erosion and sediment delivery models is therefore necessary accurate sediment yield data like the one presented in this study however are needed to validate these models

pedological analysis as a key for reconstructing primary loess relief a case study from the magdalenian site in klementowice eastern poland abstract the subject of the study was a gentle and smooth loess slope featuring a magdalenian culture site located near the northern edge of the loess belt in eastern poland based on the probing of 130 soil profiles across a 10 10 m mesh within an area of 1 2 ha the land surface after the deposition of weichselian loess was reconstructed soil mapping indicated the patchwork character of the present soil cover which consists of luvisols of varying degrees of transformation resulting from agricultural use partly eroded and buried soils co occur in the upper part of the ridge flat non eroded soils in the middle part and eroded soils in the lower part in the archaeological site area with buried soils at the foot of the slope the thickness of the primary soil cover was reconstructed by means of geostatistical analyses this was used to reconstruct the primary undulating land relief characterised by numerous small convex forms small hillocks and hummocks and concave forms closed depressions and slope troughs these forms were levelled out by soil erosion in the course of agricultural use the planation of relief caused a decrease of the mean inclination by 25 and elevation difference by 13 the greatest changes occurred on the ridge flat where the denudation of small hillocks and the filling of closed depressions took place local inclinations decreased by up to fourfold and in some places the inversion of slope exposure occurred during the 210 years of agricultural use the eroded surfaces subsided by an average of 0 32 m and at most by 0 92 m which corresponds to an average of 1 5 mm and 4 3 mm per annum respectively less than 50 of the eroded soil material was deposited within the investigated slope most of the material was carried off beyond it the accumulated surface however is 2 5 times smaller than the eroded surface hence the accumulation indicators are slightly higher than the erosion indicators

the antarctic dipole and its predictability this study investigates the nature of interan nualvariability ofantarcticseaiceanditsrelationshipwith the tropical climate we nd that the dominant interan nual variance structure in the sea ice edge and surface air temperature elds is organized as a quasi stationary wave which we call the antarctic dipole adp it is charac terized by an out of phase relationship between the ice and temperature anomalies in the central eastern pacic and atlantic sectors of the antarctic the dipole consists of a strong standing mode and a weaker propagating motion within each basin s ice eld it has the same wavelength as the antarctic circumpolar wave acw and dominates the acw variance the dipole is clearly associated with tropical enso events it can be predicted with moderate skill using linear regression involving surface temperature two to four months ahead the prediction performs better in extreme warm cold years and best in la ni na years

high resolution gully erosion and sedimentation processes and land use changes since the bronze age and future trajectories in the kazimierz dolny area naleczow plateau se poland abstract this paper presents the results of 40 years of research on the gully system in the doly podmularskie catchment 0 35 km in size which is situated in the south western part of the loess covered naleczow plateau in se poland topographic stratigraphic and pedologic investigations and monitoring of a tributary gully gully area 0 7 ha catchment 2 5 ha were combined with historical archaeological and palaeoecological records the results reveal a long and complex history in terms of the temporal and spatial extent and the impact of land use on gully erosion and the long term feed back mechanisms between land use changes and natural processes since the end of the pleistocene phases of gully erosion and subsequent filling occurred in the bronze age and around the 10th to 11th centuries the most severe deepening and expansion of the gully took place in the 17th century the results also show that field structures and land use intensity had a significant influence on the frequency and magnitude of run off soil erosion piping and landslide events the last significant erosion phase started in the mid 19th century with renewed headward retreat and down cutting within older gully fills today most of the catchment is either forested or the land is covered in berry shrubs in the future the area will continue to produce sediments because of the steep slopes and because there are still areas of bare soil with a low resistance to erosion a legacy from past land uses which will remain a factor affecting soil erosion and sedimentation processes in the future this study is an example of how important it is to observe and understand slow geomorphologic processes and rare extreme events in the light of land use changes when investigating long term human environment interactions

potential sea ice predictability and the role of stochastic sea ice strength perturbations ensemble experiments with a climate model are carried out in order to explore how incorporating a stochastic ice strength parameterization to account for model uncertainty affects estimates of potential sea ice predictability on time scales from days to seasons the impact of this new parameterization depends strongly on the spatial scale lead time and the hemisphere being considered whereas the representation of model uncertainty increases the ensemble spread of arctic sea ice thickness predictions generated by atmospheric initial perturbations up to about 4 weeks into the forecast rather small changes are found for longer lead times as well as integrated quantities such as total sea ice area the regions where initial condition uncertainty generates spread in sea ice thickness on subseasonal time scales primarily along the ice edge differ from that of the stochastic sea ice strength parameterization along the coast lines and in the interior of the arctic for the antarctic the influence of the stochastic sea ice strength parameterization is much weaker due to the predominance of thinner first year ice these results suggest that sea ice data assimilation and prediction on subseasonal time scales could benefit from taking model uncertainty into account especially in the arctic

on the structure and the transport of the eastern weddell gyre abstract the circulation pattern and volume transports in the eastern weddell gyre are estimated on the basis of hydrographic data collected by r v polarstern between 1989 and 1996 in the northeastern edge of the weddell gyre eastward flowing water masses from the antarctic circumpolar current and the weddell sea converge due to the strong effect of topographic constraints on ocean currents in the weakly stratified waters of high latitudes the wedge like structure of the southwest indian ridge can cause the convergence the increased shear leads to instabilities of the current at the eastern end of the ridge which produce an intense mesoscale eddy field between 15 and 30 e in the eddies water from the weddell cold regime and the antarctic circumpolar current waters mix and form the water masses of the weddell warm regime these waters are advected southward and flow towards the westward southern rim current which is driven by the antarctic eastwind band hence there is not a continous flow from the northern to the southern rim but a decay of the mean flow in the northeast and a reformation in the south volume transports across the greenwich meridian estimated on the basis of a combined ctd adcp data set result in an eastward flow of 61 sv in the northern rim current and a westward return flow of 66 sv in the southern part of the gyre the transport is about twice as high as previous estimates between kapp norvegia and the northern tip of the antarctic pensinsula indicating a significant gyre circulation north of 70 s

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

wave driven zonal flow vacillation in the southern hemisphere the variability of the zonal mean flow in the southern hemisphere during the period 1985 94 is studied using european centre for medium range forecasts analyses the dominant mode of variability has approximately equivalent barotropic variations of opposite signs centered at 40 8 and 608s this structure is dominant in all seasons and has similar variance in all seasons the temporal variance of the amplitude of this mode is well modeled as gaussian red noise with a correlation e folding time of about 10 days zonal wind anomalies are maintained against frictional drag by variations in the zonal flow accelerations driven by transient eddies and associated mean meridional circulations the eddy structures suggest that equatorward propagation is favored when the jet is displaced poleward and zonal propagation is favored when the jet is displaced equatorward

twentieth century simulation of the southern hemisphere climate in coupled models part ii sea ice conditions and variability we examine the representation of the mean state and interannual variability of antarctic sea ice in six simulations of the twentieth century from coupled models participating in the intergovernmental panel on climate change fourth assessment report the simulations exhibit a largely seasonal southern hemisphere ice cover as observed there is a considerable scatter in the monthly simulated climatological ice extent among different models but no consistent bias when compared to observations the scatter in maximum winter ice extent among different models is correlated to the strength of the climatological zonal winds suggesting that wind forced ice transport is responsible for much of this scatter observations show that the leading mode of southern hemisphere ice variability exhibits a dipole structure with anomalies of one sign in the atlantic sector associated with anomalies of the opposite sign in the pacific sector the observed ice anomalies also exhibit eastward propagation with the antarctic circumpolar current as part of the documented antarctic circumpolar wave phenomenon many of the models do simulate dipole like behavior in sea ice anomalies as the leading mode of ice variability but there is a large discrepancy in the eastward propagation of these anomalies among the different models consistent with observations the simulated antarctic dipole like variations in the ice cover are led by sea level pressure anomalies in the amundsen bellingshausen sea these are associated to different degrees in different models with both the southern annular mode and the el nino southern oscillation enso there are indications that the magnitude of the influence of enso on the southern hemisphere ice cover is related to the strength of enso events simulated by the different models

on the fate of the antarctic slope front and the origin of the weddell front 1 data from the deep ocean ventilation through antarctic intermediate layers dovetail and antarctic large scale box analysis and the role of the scotia sea albatross projects are combined in the region of the antarctic peninsula and the south scotia ridge to determine the paths and transports associated with the antarctic coastal current the antarctic slope front and the weddell front the antarctic coastal current flows over the antarctic continental shelf and is not tied to a particular isobath it transports 1 sv westward to the bransfield strait its subsequent course is uncertain but we speculate that it may continue southwest along the western side of the antarctic peninsula close to the coast the antarctic slope front present almost all the way around antarctica tied to the continental slope has not previously been mapped after it reaches the tip of the antarctic peninsula we show that the frontal jet splits into two branches in the northwest powell basin where the isobaths diverge the shoreward portion of the water associated with the front lying above isobaths shallower than 1500 m is able to cross the south scotia ridge and head northwestward and retains many of the properties of the antarctic slope front it is associated with a transport of 7 sv the portion of the front constrained to lie above isobaths deeper than 1500 m becomes the weddell front this takes a path around the northern powell basin and south of the south orkney islands of the 13 sv that circulates around the southern flank of the south orkney plateau 8 sv of weddell sea deep water and warm deep water leaves the front to continue west the remaining shallow and intermediate water retroflects and returns south associated with the weddell front through the orkney passage approximately 5 7 sv is transported eastward associated with the weddell front tied closely to the southern flanks of the bruce and discovery banks above the 2000 2500 m isobaths and forming the southern boundary of the weddell scotia confluence

modelling water flow and sediment processes in a small gully system on the loess plateau in china abstract a single gully system was selected in a small agricultural watershed on the loess plateau of china with the objective of measuring and then simulating water and sediment transport and defining alternative land uses to reduce discharge and soil loss the gully had a total length of about 40 m and was about 30 m wide the watershed feeding the gully occupied about 1950 m 2 including the gully itself the gully bottom had a slope of about 32 40 whereas the gully walls were from 40 to over 60 soil water content and water and sediment discharge were measured automatically the physically based hydrological and soil erosion model lisem was used to calculate water and sediment discharge calibration has been carried out for one event by adjusting the saturated conductivity values validation was performed for two additional runoff events calibration results show reasonably comparable hydrographs between measured and calculated discharge lisem could be calibrated on the hydrograph quite satisfactorily using the saturated conductivity as a calibration factor also validation of lisem for two other runoff events showed reasonably good results the calibration on total soil loss also shows good results for the validation runs these results are poor probably due to limitations of the measurement equipment and the incapability of the model to simulate small events scenario analyses showed that forest as an alternative land use for the gully bottom will result in significantly lower water and sediment this strongly supports the implementation of the reforestation policy recently suggested and activated by the central government of the p r china

a 400 km long piggyback basin upper aptian lower cenomanian in the eastern alps piggyback basins ori and friend 1984 comprise sedimentary basins that formed on active thrust sheets based on basin geometry and depositional systems two end member types of piggyback or thrust top basins have been distinguished type 1 basins are deep water basins that occur mainly as elongated synsedimentary deforming troughs in the footwall of thrusts in the early stages of orogenic wedge development and under lled foreland basins e g ori and friend 1984 lash 1990 type 2 piggyback basins are terrestrial to shallow marine intramontane basins that are formed predominantly during late orogenic stages e g ori and friend 1984 nijman 1998 this paper describes the geometry and evolution of an early deepmarine piggyback trough that formed on the cretaceous orogenic wedge of the eastern alps and the western carpathians the narrow basin extended over a considerable horizontal distance as suggested by similarities in stratigraphy and the timing of deformation the basin characterized a signi cant stage in the cretaceous evolution of the austroalpine northern boundary

assessing pelagic palaeoenvironments using foraminiferal assemblages a case study from the late campanian radotruncana calcarata zone upper cretaceous austrian alps abstract two upper campanian sections in the austrian alps representing the north western tethyan biogeographic realm from either sides of the penninic ocean alpine tethys have been examined aiming at a high resolution assessment of foraminiferal assemblages the postalm section from the northern calcareous alps southern active margin and the oberhehenfeld section from the ultrahelvetics northern passive margin this study focuses on plankton biostratigraphy and foraminiferal palaeoecology of the radotruncana calcarata total range zone the postalm section displays cyclic red deposits with marls and marly limestones while we find uniform grey marls at oberhehenfeld the oberhehenfeld section from the ultrahelvetics can be correlated stratigraphically to the postalm section using foraminifera calcareous nannoplankton and stable isotope stratigraphy and provides a point of comparison from the northern margin of the penninic ocean the two sections show minimal difference in faunal composition and few distinct local stratigraphic signals palaeoenvironmental trends from the late campanian can be recognised relating the two sections from the austrian alps the depositional water depth can be reconstructed as some 500 800 m plankton assemblages show a remarkable stability despite the sudden appearance and disappearance of r calcarata hinting at the late campanian as a time interval of general foraminiferal stasis without significant evolutionary events we speculate that the origin and extinction of r calcarata are related to the prolonged evolution of ocean stratification during the campanian from the mid cretaceous sluggish hothouse during a time of general slow greenhouse climate decline

phases of alluvial fan development in a loess area lublin upland e poland abstract holocene alluvial fans are a record of the evolution of the environment and human impact over the last 10 000 years the study presents the structure of fans at the mouth of gullies as well as their development in the loess areas of the lublin upland sediment soil sequences of seven alluvial fans and the adjoining flood sediments and dry valley bottom sediments were studied in detail the development of fans occurred in three phases i the eneolithic ii the middle and late bronze age and the hallstatt period and iii the middle ages and the modern times the middle phase consists of two sub phases while last phase consists of three sub phases the early middle ages the little ice age the 19th and first half of the 20th century these phases were interspersed with longer or shorter periods of stabilization of the alluvial fan surface the different course of land use changes in the catchments was the reason for this metachronous development of the alluvial fans our studies indicate that heavy and catastrophic rainfall and rapid thaw had a considerable role in the development of the alluvial fans the establishment of roads along the axes of valleys and across the slopes had a key impact on alluvial fan development the deforestation of the catchment was not an essential condition for the formation of gullies and alluvial fans

the reemergence of sst anomalies in the north pacific ocean abstract sea surface temperature sst data and two different upper ocean temperature analyses are used to study the winter to winter recurrence of sst anomalies in the north pacific ocean the ssts recur when temperature anomalies that form in the deep ocean mixed layer in late winter early spring are isolated from the atmosphere in the summer seasonal thermocline and then reemerge at the surface when the mixed layer deepens during the following fall winter this reemergence mechanism is evaluated over the basin by correlating the time series of the leading pattern of ocean temperature anomalies in the summer seasonal thermocline 60 85 m in august september with sst anomalies over the course of the year the results indicate that the dominant large scale sst anomaly pattern that forms in the north pacific during late winter with anomalies of one sign in the central pacific and the opposite sign along the coast of north america is sequestered in the seasonal thermocline in summer and returns to the

modeling water mass formation in the mertz glacier polynya and adelie depression east antarctica 1 high rates of sea ice growth and brine rejection in the mertz glacier polynya drive the production of dense continental shelf waters in the adelie depression we consider the rate of outflow of waters having sufficient density to sink into the neighboring abyssal ocean and form adelie land bottom water albw along with weddell and ross sea bottom waters the albw is an important source of antarctic bottom water the relevant processes are modeled using a variant of the max planck institute ocean model mpiom under daily ncep ncar reanalysis forcing for the period 1991 2000 the orthogonal curvilinear horizontal grid allows for the construction of a global domain with high resolution in our region of interest the modeled mertz glacier polynya is realistic in location and extent exhibiting low ice thickness 0 4 m and low ice fraction 50 the net surface ocean to atmosphere heat flux exceeds 200 w m2 and is dominated by sensible heat exchange in wintertime may through september inclusive 7 5 m of sea ice forms over the adelie depression at a rate of 4 9 cm d 1 this results in annual average volumetric production of 99 km3 of sea ice the associated brine release drives dense shelf water formation the off shelf flow of dense water exhibits strong interannual variability in response to variability in both atmospheric forcing and ocean preconditioning averaged over the period 1991 2000 the off shelf flow of dense water is 0 15 sv for a period of strong outflow 1993 1997 this increases to 0 24 sv most of the outflow occurs during july through october at a rate of 0 40 0 63 sv over the period 1991 2000 1993 1997 the peak mean monthly outflow can exceed 1 sv

assessment of soil losses by ephemeral gully erosion using high altitude stereo aerial photographs the objective of this study is to explore in a critical way the potential of high altitude stereo aerial photographs for the assessment of ephemeral gully erosion rates on 28 may 1995 an intensive rainfall event 30 mm h 1 during 30 min return period 3 years occurred in central belgium ephemeral gullies formed within an area of 218 ha study area 1 were mapped and measured both in the field and by high altitude aerial photos taken at the same time comparison of these two methods shows that if only one of the two surveying techniques had been used only 75 per cent of the total ephemeral gully length would have been detected so that the combination of aerial and field data leads in fact to the best possible determination of total gully length within the selected area a correction factor c is proposed so that the results of an ephemeral gully erosion survey based on high altitude stereo aerial photos can be adjusted for the undetected gullies next a sequential series of high altitude stereo aerial photographs taken in six different years was analysed in order to determine ephemeral gully erosion rates in three selected study areas study areas 2 3 and 4 selection criteria were chosen so that these three areas were similar to study area 1 and representative for the cultivated areas in central belgium where intense soil erosion regularly occurs ephemeral gullies were mapped and their total length was measured from the aerial photos using a mean gully cross section of 0 2635 m2 determined in study area 1 the average eroded volume is 1 89 m3 ha 1 in six months for study area 1 0 86 m3 ha 1 in six months for area 2 1 44 m3 ha 1 in six months for area 3 and 2 37 m3 ha 1 in six months for area 4 according to the correction factor c these mean ephemeral gully erosion volumes have to be increased by 44 per cent the ephemeral gully erosion rates based on high altitude stereo aerial photos correspond well with the results of other surveys carried out in the belgian loess belt copyright 1999 john wiley sons ltd

changes in antarctic temperature wind and precipitation in response to the antarctic oscillation output of a 14 year integration with a high resolution 55 km 55 km regional atmospheric climate model is used to study the response of antarctic near surface climate to the antarctic oscillation aao the periodical strengthening and weakening of the circumpolar vortex in the southern hemisphere in spite of the relatively short record wind temperature and precipitation show widespread and significant aao related signals when the vortex is strong high aao index northwesterly flow anomalies cause warming over the antarctic peninsula ap and adjacent regions in west antarctica and the weddell sea in contrast cooling occurs in east antarctica the eastern ross ice shelf and parts of marie byrd land most of the annual temperature signal stems from the months march august the spatial distribution of the precipitation response to changes in the aao does not mirror temperature changes but is in first order determined by the direction of flow anomalies with respect to the antarctic topography when the vortex is strong high aao index the western ap becomes wetter while the ross ice shelf parts of west antarctica and the lambert glacier basin east antarctica become drier

the value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess derived soils abstract a data set on soil losses and controlling factors for 58 ephemeral gullies has been collected in the belgian loess belt from march 1997 to march 1999 of the observed ephemeral gullies 32 developed at the end of winter or in early spring winter gullies and 26 ephemeral gullies developed during summer summer gullies the assessed data have been used to test the physically based ephemeral gully erosion model egem and to compare its performance with the value of simple topographical and morphological indices in the prediction of ephemeral gully erosion analysis shows that egem is not capable of predicting ephemeral gully cross sections well although conditions for input parameter assessment were ideal some parameters such as channel erodibility critical flow shear stress and local rainfall depth showed great uncertainty rather than revealing egem s inability of predicting ephemeral gully erosion this analysis stresses the problematic nature of physically based models since they often require input parameters that are not available or can hardly be obtained with respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion this study shows that for winter gullies and summer gullies respectively over 80 and about 75 of the variation in ephemeral gully volume can be explained when ephemeral gully length is known moreover when previously collected data for ephemeral gullies in two mediterranean study areas and the data for summer gullies formed in the belgian loess belt are pooled it appears that one single length l volume v relation exists v 0 048 l 1 29 r 2 0 91 these findings imply that predicting ephemeral gully length is a valuable alternative for the prediction of ephemeral gully volume a simple procedure to predict ephemeral gully length based on topographical thresholds is presented here secondly the empirical length volume relation can also be used to convert ephemeral gully length data extracted from aerial photos into ephemeral gully volumes

abandonment of the south penninic austroalpine palaeosubduction zone central alps and shift from subduction erosion to accretion constraints from rb sr geochronology abstract we present new age data for the evolution of the suture zone between lower plate south penninic and upper plate austroalpine units in the central european alps rb sr deformation ages for mylonitized rocks of the south penninic palaeosubduction melange and for deformed austroalpine basement eastern switzerland shed light on the pre alpine and alpine deformation history along the suture as well as on synsubduction interplate mass transfer rb sr age data define two age groups the first group reflects pre alpine events within the upper plate basement with varying degree of resetting by subsequent alpine overprints the second group marks the waning of subduction related deformation along the south penninic austroalpine suture zone at around 50 ma and termination at c 47 ma identical rb sr ages for pervasively deformed austroalpine and south penninic lithologies point to tectonic erosion of the upper plate during subduction we propose that underplating of the middle penninic micro continent at c 50 ma led to the cessation of deformation within the south penninic melange and shifted the zone of active deformation into the footwall this also caused a contemporaneous upper plate surface uplift and shutoff of sedimentation in alpine gosau type forearc basins

deep structure and kinematics of the northern calcareous alps transalp profile the northern calcareous alps nca of southern bavaria and northern tyrol constitute a carbonate dominated polyphase fold thrust wedge together with its grauwacken zone basement it is the northernmost part of the far travelled upper austroalpine thrust complex of the eastern alps the present geometry developed in several kinematic stages jurassic extensional faults that affected large parts of the nca and their basement originated when the main part of the nca was still located southeast of the central alpine otztal silvretta complex these faults and related facies transitions influenced the later style of detachment of the nca thrust sheets mid to late cretaceous detachment thrust sheet stacking and motion over the central alpine complex are registered in clastic deposits of syntectonic basins the latest cretaceous to cenozoic nne to n directed motion of the nca towards europe in front of the central alpine complex created another set of significant contraction structures which at depth overprinted all previous structures during cretaceous to cenozoic deformation the nca experienced about 80 km of shortening i e about 73 along the transalp profile the european basement and autochthonous mesozoic cover beneath the allochthonous nca thrust sheets and flysch complexes seem to have remained relatively undeformed

transpressional collision structures in the upper crust the fold thrust belt of the northern calcareous alps abstract two major structural events characterize the tectonic evolution of the northern calcareous alps nca 1 late early cretaceous to late eocene nw directed dextral transpressional stacking of nappes as an expression of the formation of the austroalpine orogenic wedge and 2 miocene sinistral wrenching due to eastward lateral extrusion of crustal wedges along the central eastern alps three first order detachment horizons are defined by differences of competence within areas of facies transition preexisting normal faults control the thrust architecture transpressional contraction in the nca is indicated by a nw directed thrusting oblique to both the long axis of the nca and the edge of the orogenic foreland b the occurrence of en echelon arrays of thrusts and folds laterally displaced by dextral strike slip faults the thrusts and strike slip faults are kinematically connected to each other and dissect the nca into rhomboidal blocks c ne directed extension parallel to fold and ramp axes and the internal strike of the nca and d clockwise rotation 30 of the entire nca around a vertical axis kinematic and dynamic analysis of mesoscale fault striae data related to transpressional stacking indicates a nw trend of contraction directions and in general a ne trend of the extension directions parallel to fold axes and branch lines of thrusts before rotation the average contraction direction was probably parallel to the generally w directed shear direction recorded in the crystal plastically deformed central part of the eastern alps three balanced cross sections across the nca yield a minimum of 54 65 total shortening

paleobiogeography and historical biogeography of the non marine caenogastropod family melanopsidae abstract we investigate the distributions of representatives of the family melanopsidae gastropoda caenogastropoda cerithioidea from the late cretaceous to present day the present contribution discusses and partly revises former schemes of melanopsid dispersal during the cenozoic all of which were based on outdated stratigraphic and tectonic concepts as well as an incompletely considered fossil record conflating a comprehensive and stratigraphically well constrained fossil record modern paleogeographical reconstructions and contemporary climate data our goal is to present a thorough model of melanopsid distribution and its changes over the cenozoic as well as its paleogeographical and climatic constraints the family melanopsidae evolved about 90 ma ago in the late turonian from brackish cerithioidean ancestors cretaceous and paleogene species occur in marginal marine to brackish environments along the shores of the tethys and paratethys seas the extant clades of melanopsis likely derive from the evolution of freshwater melanopsis on the balkan peninsula back in the late early miocene up to the pliocene freshwater species spread toward southwestern and southeastern europe and successively replaced brackish water representatives paralleling a general decline of latter systems during the late cenozoic the southwards expansion of melanopsis and its simultaneous retreat from northern latitudes resulted in the disjunct distribution pattern observed today the genus holandriana first appeared in northern italy in the late early miocene the genera microcolpia and esperiana both first occurred in the late miocene and likely derive from brackish water melanopsis species native to peri paratethyan lakes the present day biogeographic isolation of the three latter genera and melanopsis roots in the climatic deterioration and the disappearance of major lake systems in southeastern europe while thermophilous melanopsis retreated to the warm dry climates of the mediterranean and middle east holandriana microcolpia and esperiana adapted to the seasonal cold temperate climate of southeastern and eastern europe and some species became restricted to thermal springs

multiple jets of the antarctic circumpolar current south of australia abstract maps of the gradient of sea surface height ssh and sea surface temperature sst reveal that the antarctic circumpolar current acc consists of multiple jets or frontal filaments the braided and patchy nature of the gradient fields seems at odds with the traditional view derived from hydrographic sections that the acc is made up of three continuous circumpolar fronts by applying a nonlinear fitting procedure to 638 weekly maps of ssh gradient ssh it is shown that the distribution of maxima in ssh i e fronts is strongly peaked at particular values of absolute ssh i e streamlines the association between the jets and particular streamlines persists despite strong topographic and eddy mean flow interactions which cause the jets to merge diverge and fluctuate in intensity along their path the ssh values corresponding to each frontal branch are nearly constant over the sector of the southern ocean between 100 e and 180 the front positions inferred from ssh agree closely with

the shochary ridge sequence southeastern pennsylvania a possible ordovician piggyback basin fill abstract the central appalachian orogen of eastern pennsylvania is underlain in part by three fault bounded deep water clastic sequences the windsor township formation of the hamburg klippe greenwich slice the martinsburg formation and the shochary ridge sequence deep water sandstones of the windsor township formation were deposited in a trench on oceanic lithosphere in early middle ordovician time clastic detritus of the late middle early late ordovician martinsburg formation accumulated as part of a longitudinal deep sea clastic system in the central appalachian foreland basin deposits of the coeval shochary ridge sequence comprise a 1500 m thick coarsening upward sequence of hemipelagic mudstone and siltstone turbidites although devoid of the type of bedding cyclicity implicit to published submarine fan models the shochary ridge sequence may have accumulated as part of a morphologically poorly developed deep sea fan in which submarine channels and depositional lobes never formed or were poorly developed at best the coarsening upward nature of the shochary ridge sequence probably reflects progradation of its depositional system in response to either an inferred late middle early late ordovician glacially induced reduction in sea level and or an increase in tectonic activity in the hinterland sedimentologic and paleocurrent data suggest that deposits of the shochary ridge sequence did not accumulate as part of the martinsburg depositional system palinspastic restoration places the shochary ridge depocenter to the southeast of the martinsburg basin i e on the orogen side of the foreland basin accordingly the shochary ridge sequence is interpreted to reflect gradual filling of a basin that existed within the active thrust terrane to the southeast of the martinsburg depocenter this basin a piggyback or slope basin formed on martinsburg strata that had been tectonically incorporated into the northwest migrating thrust terrane as the frontal thrust advanced into the foreland basin

40ar 39ar laser probe dating of detrital white micas from cretaceous sedimentary rocks of the eastern alps evidence for variscan high pressure metamorphism and implications for alpine orogeny the detritus of cretaceous synorogenic sandstones of the northern margin of the austroalpine microplate contains evidence for a high pressure metamorphic basement and obducted oceanic crust exposed in early alpine time 40 ar 39 ar laser probe data of detrital white micas give excellent plateau ages in a narrow range from 320 to 360 ma white micas cover the whole range from muscovites up to phengites 3 04 to 3 48 si per formula unit heavy mineral spectra contain chrome spinel glaucophane chloritoid epidote and garnet as well as zircon tourmaline and rutile glaucophane chloritoid and phengite correlate in their abundance these minerals also correlate positively with the stable minerals zircon tourmaline and rutile derived from continental rock and negatively with chrome spinel which represents oceanic crustal provenance we propose that both glaucophane and phengite come from the same source rock variscan high pressure metamorphic rocks of the austroalpine basement the early carboniferous age gives constraints for paleogeographic models concerning the collision between gondwana and laurussia furthermore detrital glaucophane in the early alpine sedimentary rocks cannot be used as proof for cretaceous subduction at the austroalpine penninic plate boundary

cyclicity and basin axis shift in a piggyback basin towards modelling of the eocene tremp ager basin south pyrenees spain

reestablishing the circumpolar wave in sea ice around antarctica from one winter to the next remarkable correlation exists between warm water poleward winds over the ocean and low sea ice concentrations and extents over the winter sea ice pack around antarctica even to the point of continuing paterns across the ice sea boundary since the wind stress associated with poleward wind is expected to compact the ice during sea ice edge retraction we conclude that the memory of the antarctic circumpolar wave in the sea ice pack is carried from one austral winter to the next by the neighboring water temperatures since the sea ice pack retracts nearly to antarctica in austral summer

an antarctic circumpolar wave in surface pressure wind temperature and sea ice extent the southern ocean is the only oceanic domain encircling the globe it contains the strong eastward flow of the antarctic circumpolar current and is the unifying link for exchanges of water masses at all depths between the world s major ocean basins1 as these exchanges are an important control on mean global climate the southern ocean is expected to play an important role in transmitting climate anomalies around the globe interannual variability has been often observed at high southern latitudes and observations of sea ice extent suggest that such features propagate eastwards around the southern ocean2 3 here we use data from a variety of observational techniques to identify significant interannual variations in the atmospheric pressure at sea level wind stress sea surface temperature and sea ice extent over the southern ocean these anomalies propagate eastward with the circumpolar flow with a period of 4 5 years and taking 8 10 years to encircle the pole this system of coupled anomalies which we call the antarctic circumpolar wave is likely to play an important role in climate regulation and dynamics both within and beyond the southern ocean

sea ice winter convection and the temperature minimum layer in the southern ocean the structure of the near surface waters in the southern ocean poleward of the antarctic polar front but away from continental margins is investigated with a three dimensional time dependent numerical model which resolves the annual sea ice cycle the growth and decay of the ice field is predicted using one of semtner s 1976 thermodynamic ice models in terms of specified atmospheric data and computed thermohaline characteristics of the ocean layers the ice field is found to be sensitive to the lateral advection of heat by the oceanic circulation as well as vertical heat transports due to deep winter convection the model treats the temperature minimum layer in the southern ocean as the remnant of a deep winter mixed layer which becomes capped by surface heating and precipitation in summer the predicted thermohaline characteristics of the temperature minimum layer and the surface mixed layer are in good agreement with observations finally the annual air sea heat exchange predicted by the model is discussed the model s predicted area averaged heat loss experienced by the ocean south of the atlantic polar front is much smaller than was previously estimated this is attributed to errors in the southern region of the model domain it is suggestedmore that models which include the interactions between sea ice and surface deep and bottom waters along the continental margins are needed to investigate this region less

landform transformation and long term sediment budget for a chernozem dominated lowland agricultural catchment abstract the loess hilly lands of the south west foreland of the west carpathians are characterized by favorable climatic conditions smooth topography fertile soils and a long settlement history for the first time we document changes to human induced landforms in a small zero order dry valley 0 28 km2 with calcic chernozem soils and develop a long term sediment budget the original surface was reconstructed based on interpreting records of erosion and deposition from 185 soil cores and six valley cross sections the topography inherited from the pleistocene was transformed through lowering of hillslope ridges and convexities along with infilling of shallow depressions within the original valley bottom on convex convex landforms had an average net erosion of 0 32 0 01 m while average net accumulation in the valley bottom was estimated at 0 20 0 01 m the correlation between change in soil profile depth with profile curvature 0 51 p

soil loss rates due to piping erosion compared with surface soil erosion by water subsurface erosion piping is generally less studied and harder to quantify however wherever piping occurs it is often a significant or even the main sediment source in this study the significance of soil loss due to piping is demonstrated through an estimation of soil volume lost from pipes and pipe collapses n 560 in 137 parcels under pasture on loess derived soils in a temperate humid climate belgium assuming a period of 5 to 10 years for pipe collapse to occur mean soil loss rates of 2 3 and 4 6 t ha 1 yr 1 are obtained which are at least one order of magnitude higher than surface erosion rates 0 01 0 29 t ha 1 yr 1 by sheet and rill erosion under a similar land use the results obtained for the study area in the flemish ardennes correspond well to other measurements in temperate environments they are however considerably smaller than soil loss rates due to subsurface erosion in semi arid environments although local slope gradient and drainage area largely control the location of collapsed pipes in the study area these topographic parameters do not explain differences in eroded volumes by piping hence incorporation of subsurface erosion in erosion models is not straightforward copyright 2011 john wiley sons ltd

watermass properties of the antarctic slope front a simple model abstract in the antarctic dense shelf water is formed in coastal polynyas and is differentiated from the fresher surface water by the wind induced ice motion that displaces offshore the ice melt from production zones where the shelf water discharges into the deep ocean the antarctic slope front asf is v shaped separating the shelf and surface waters referred to as frontal waters from the circumpolar deep water cdw to elucidate basic constraints on frontal properties a minimal model of homogeneous water masses forced by offshore wind and freshwater input in a perpetual winter is considered with the surface water stirred by and hence aligned with the ice cover there is little leakage of ice or meltwater from the frontal system so ice production and melt merely redistribute heat and salt between frontal waters as such the heat loss to the atmosphere needs to be supplied by entraining cdw which then necessitates the shelf water discharge on account of the mass balance because of the fresh

links between the amundsen sea low and sea ice in the ross sea seasonal and interannual relationships previous studies have shown that sea ice extent in the southern ocean is influenced by the intensity and location of the amundsen sea low asl through their effect on the meridional winds however the inhomogeneous nature of the influence of the asl on sea ice as well as its influence during critical periods of the sea ice annual cycle is not clear in this study we do a spatio temporal analysis of links between the asl and the sea ice during the advance and retreat periods of the ice over the period 1979 2013 focusing on the role of the meridional and zonal winds we use the era interim monthly averaged 500 mb geopotential height and 10 m wind data along with monthly passive microwave sea ice concentrations sic to examine the seasonal and interannual relationships between the asl and sic in the ross amundsen sea ice sector to characterize the state of the asl we use indices that describe its location and its intensity we show that the asl has preferred locations and intensities during ice advance and retreat seasons the strength and direction of the influence of the asl are not spatially homogeneous and can change from advance to retreat season and there are strong significant relationships between the characteristics of the asl and sic within and across seasons and interannually

exposed plate interface in the european alps reveals fabric styles and gradients related to an ancient seismogenic coupling zone 1 we present observations from a continuous exposure of an ancient plate interface in the depth range of its former seismogenic zone in the central alps of europe related to late cretaceous early tertiary subduction and accretion of the south penninic lower plate underneath the adriatic upper plate the material forming the exposed plate interface zone has experienced flow and fracturing over an extended period of time followed by syncollisional exhumation thus reflecting a multistage evolution fabric formation and metamorphism however chiefly record the deformation conditions of the precollisional setting along the plate interface we identify an unstable slip domain from pseudotachylytes occurring in the temperature range between 200 and 300 c this zone coincides with a domain of intense veining in the subduction melange with mineral growth into open cavities indicating fast possibly seismic rupture evidence for transient near lithostatic fluid pressure as well as brittle fractures competing with mylonitic shear zones continues into the region below the occurrence of pseudotachylytes possibly reflecting a zone of conditionally stable slip the zone above the unstable slip area is devoid of veins but displays ample evidence of fluid assisted processes similar to the deeper zone solution precipitation creep and dehydration reactions in the melange matrix hydration and sealing of the base of the upper plate seismic rupture here is possibly expressed by ubiquitous localized deformation zones we hypothesize that trenchward sealing of parts of the plate interface as well as reaction enhanced destruction of upper plate permeability is an important component localizing the unstable slip zone this relation may result from the competition of the pervasive presumably interseismic pressure solution creep destroying permeability and building elevated fluid pressure until the strength threshold is reached with seismic failure

fronts transport and weddell gyre at 30 e between africa and antarctica a detailed description of the frontal structure of major currents and estimates of transport between africa and antarctica at 30 e were made on the basis of a finely resolved hydrographic section made during the 1996 civa 2 cruise particular emphasis was put on a refinement of the eastern boundary of the weddell gyre by analyzing also supplementary hydrographic data from the 1993 civa 1 cruise and the best available historical hydrographic data in the weddell and enderby basins contrary to the general belief our results show that the weddell gyre extends far beyond 30 e reaching at least as far east as the enderby land promontory 53 e from this point westward currents along the antarctic continental margin constitute the gyre s southern boundary thus closing the cyclonic circulation of the gyre at its easternmost end as the most convincing evidence for this refined circulation scheme significant westward transport south of 65 s has been identified from the civa 1 acoustic doppler current profiler data we have shown also using an inertial jet model that the blocked feature of the weddell cold regime 57 s to the west of 25 e is due to the topographic control of flow by local bathymetry during the civa 2 cruise 70 of the antarctic circumpolar current acc was concentrated near the polar front 51 s with surface speeds reaching up to 70 cm s 1 the baroclinic current field in the subpolar area south of the weddell front 58 s for civa 2 and 57 s for civa 1 is featureless 3 cm s 1 but yielding a nonnegligible eastward transport of 15 sv 1 sv 106 m3 s 1 this bottom referenced baroclinic transport is entirely compensated by a substantial westward barotropic transport south of 65 s the acc transport across the 30 e section during the civa 2 cruise is estimated to be 160 sv

synchronous variability in the southern hemisphere atmosphere sea ice and ocean resulting from the annular mode zonally symmetric fluctuations of the midlatitude westerly winds characterize the primary mode of atmospheric variability in the southern hemisphere during all seasons this is true not only in observations but also in an unforced 15 000 yr integration of a coarse resolution r15 coupled ocean atmosphere model here it is documented how this mode of atmospheric variability known as the southern annular mode sam generates ocean circulation and sea ice variations in the model integration on interannual to centennial timescales that are tightly in phase with the sam the positive phase of the sam is associated with an intensification of the surface westerlies over the circumpolar ocean around 608s and a weakening of the surface westerlies farther north this induces ekman drift to the north at all longitudes of the circumpolar ocean and ekman drift to the south at around 308s through mass continuity the ekman drift generates anomalous upwelling along the margins of the antarctic continent and downwelling around 458s the anomalous flow diverging from the antarctic continent also increases the vertical tilt of the isopycnals in the southern ocean so that a more intense circumpolar current is also closely associated with positive sam in addition the anomalous divergent flow advects sea ice farther north resulting in an increase in sea ice coverage finally positive sam drives increases in poleward heat transport at about 308s while decreases occur in the circumpolar region ocean and sea ice anomalies of the opposite sign occur when the sam is negative the ocean and sea ice fluctuations associated with the sam constitute a significant fraction of simulated ocean variability poleward of 308s year round the robustness of the mechanisms relating the sam to oceanic variability suggests that the sam is likely an important source of large scale variability in the real southern hemisphere ocean

conditions leading to the unprecedented low antarctic sea ice extent during the 2016 austral spring season the 2016 austral spring was characterized by the lowest anomalous southern hemisphere sh sea ice extent seen in the observational record 1979 present and coincided with anomalously warm surface waters surrounding most of antarctica two distinct processes contributed to this event firstly the extreme el nino event peaking in december february djf 2015 16 contributed to pronounced extra tropical sh sea surface temperature and sea ice extent anomalies in the eastern ross amundsen and bellingshausen seas that persisted in part until the following 2016 austral spring secondly internal unforced atmospheric variability of the southern annular mode promoted the exceptional low sea ice extent in november december 2016 these results suggest that a combination of tropically forced and internal sh atmospheric variability contributed to the unprecedented sea ice decline during the 2016 austral spring on top of the slow background changes expected from greenhouse gas and ozone forcing

the impact of snowmelt and heavy rainfall runoff on erosion rates in a gully system lublin upland poland the study examines water runoff and geomorphic processes within a permanent gully located in an agricultural catchment of the lublin upland southeast poland the studies were conducted in the period 2003 to 2006 during which time the volume and intensity of precipitation were recorded and water runoff and sediment concentration at the outlet of the main gully were measured after large surface runoff events that resulted in geomorphic effects erosion and accumulation forms were examined the role of snowmelt and heavy rains in the runoff of water and suspended solids from the catchment as well as their effect on the dynamics of certain processes such as rill erosion piping and accumulation within the gully all were evaluated it was observed that the gully developed spatially through piping and headcut processes during snowmelt while the main gully form became shallower as a result of accumulation processes headcut erosion at the gully bottom and transport of the material out of the catchment predominantly during pluvial runoff events were much less intensive it was estimated that the intensity of snowmelt runoff in the years 2003 to 2006 was similar to the multi annual average while the intensity of pluvial runoff was significantly lower an attempt was made to describe the dynamics of gully erosion and the direction of gully system evolution on a medium term time scale 50 to 100 years it was found that the roles of snowmelt and heavy rains in such catchments are in opposition snowmelt runoff events lead to the spatial development of the gullies and make them shallower while pluvial runoff events add to the deepening of the gully and result in transporting the material outward these two processes keep the gully system in relative balance copyright 2009 john wiley sons ltd

heavy metals in the slope deposits of loess areas of the lublin upland e poland abstract the concentration of heavy metals cd cu pb zn has been analyzed in holocene slope deposits of the loess agricultural area in the eastern poland five profiles were examined in general low concentrations of the examined metals were determined on average 50 of the samples exceeded the designated regional geochemical background the average concentrations were cadmium

winter water variability in the indian ocean sector of southern ocean during austral summer abstract winter water ww is a feature in the upper layers of the southern ocean during austral summer the interaction of this cold water with surface and deeper subsurface layers can alter the heat budget as well as the carbon cycle however the structure and characteristics of the ww in the southern ocean is poorly understood due to the lack of in situ data in this study hydrographic data collected from the indian expeditions during 2010 and 2011 and from other expeditions during 2003 2006 and 2007 in the southern ocean have been utilized to understand the ww variability and its characteristics in the region between 40 e and 90 e the analysis shows large zonal variations in the distribution of ww during austral summer east of 60 e the ww shows warmer temperature with weaker gradients than the western side which is observed to have a larger meridional extension the high frequency of eddies surface warming and upwelling of the upper circumpolar deep water due to shallow bathymetric features of the kerguelen plateau situated in the eastern side of the study region is proposed as the major mechanisms for this variability the direct impact of southern annular mode on ww variability is investigated and a short term response is observed

sedimentary basins formed and carried piggyback on active thrust sheets small sedimentary basins that formed on the apennine southern margin of the po basin complex northern italy have been studied using borehole and seismic reflection information and their evolution can be dated using the largely marine biostratigraphy of the miocene to quaternary sediments these studies show that the basins formed and were filled while being carried on moving thrust sheets and they are therefore named piggyback basins each of these basins corresponds to the active phase of a different thrust front ramp on the pyrenean northern margin of the ebro basin complex northern spain similar piggyback basins formed between eocene and mid miocene time they have since been uplifted and eroded and may therefore be studied in outcrop in northern spain much of the basin fill sediment was deposited in nonmarine environments

reconciling plate tectonic reconstructions of alpine tethys with the geological geophysical record of spreading and subduction in the alps article a new reconstruction of alpine tethys combines plate kinematic modelling with a wealth of geological data and seismic tomography to shed light on its evolution from sea floor spreading through subduction to collision in the alps unlike previous models which relate the fate of alpine tethys solely to relative motions of africa iberia and europe during opening of the atlantic our reconstruction additionally invokes independent microplates whose motions are constrained primarily by the geological record the motions of these microplates adria iberia alcapia alkapecia and tiszia relative to both africa and europe during late cretaceous to cenozoic time involved the subduction of remnant tethyan basins during the following three stages that are characterized by contrasting plate motions and driving forces 1 131 84 ma intra oceanic subduction of the ligurian part of alpine tethys attached to iberia coincided with eo alpine orogenesis in the alcapia microplate north of africa these events were triggered primarily by foundering of the older 170 131 ma neotethyan subduction slab along the ne margin of the composite african adriatic plate subduction was linked by a sinistral transform system to e w opening of the valais part of alpine tethys 2 84 35 ma subduction of primarily the piemont and valais parts of alpine tethys which were then attached to the european plate beneath the overriding african and later adriatic plates nw translation of adria with respect to africa was accommodated primarily by slow widening of the ionian sea 3 35 ma recent rollback subduction of the ligurian part of alpine tethys coincided with western alpine orogenesis and involved the formation of the gibraltar and calabrian arcs rapid subduction and arc formation were driven primarily by the pull of the gravitationally unstable retreating adriatic and african slabs during slow convergence of africa and europe the upper european iberian plate stretched to accommodate this slab retreat in a very mobile fashion while the continental core of the adriatic microplate acted as a rigid indenter within the alpine collisional zone the subducted lithosphere in this reconstruction can be correlated with slab material imaged by seismic tomography beneath the alps and apennines as well as beneath parts of the pannonian basin the adriatic sea the ligurian sea and the western mediterranean the predicted amount of subducted lithosphere exceeds the estimated volume of slab material residing at depth by some 10 30 indicating that parts of slabs may be superposed within the mantle transition zone and or that some of this subducted lithosphere became seismically transparent

thermomechanical consequences of cretaceous continent continent collision in the eastern alps austria insights from two dimensional modeling we use two dimensional numerical modeling techniques to investigate the thermomechanical consequences of closure of the meliata hallstatt ocean and consequent cretaceous continent continent collision in the eastern alps austria in the modeling a lower plate position of the austro alpine aa continental block is adopted during collision with the upper juvavic silice block the thermal structure of the lithosphere was calculated for major aa tectonic units upper middle and lower austro alpine by integration of the transient heat flow equation along an approximately nw se cross section east of the tauern window indications of the rheological evolution of the aa were determined by calculating strength profiles at key stages of the cretaceous orogeny making use of the thermal modeling predictions combined with rock mechanics data cooling in the upper plate and lower greenschist facies metamorphism within footwall parts of the lower upper austro alpine ua plate related to se directed underthrusting of the ua beneath the upper juvavic silice block at circa 100 ma were predicted by the numerical model the observed pressure temperature path for deeply buried middle austro alpine ma upper crustal units and their subsequent isothermal exhumation are best reproduced assuming a pressure peak at 95 ma and exhumation rates ranging between 4 and 7 5 mm yr 1 from the modeling results we deduce that the temperature evolution during eclogite exhumation is primarily dependent on rates of tectonic movements and largely independent of the mode of exhumation thrusting versus erosion furthermore very rapid postmetamorphic exhumation of southern lower austro alpine la units is predicted in order to account for subsequent cooling this is constrained by 40ar 39ar data the cooling paths of ma and la rocks appear to be primarily controlled by their near surface positions at the end of the cretaceous rather than by other processes such as concurrent underthrusting upward advection of heat by rapid exhumation induced thermal weakening of the thickened crust the inferred weakness of the central parts of the orogenic system may play an important role during detachment related tectonic unroofing orogenic collapse and concomitant basin formation central alpine gosau basins

is the northwestern betic cordillera mountain front active in the context of the convergent eurasia africa plate boundary the present relief of the betic rif cordillera has been mainly developed since the late miocene in the context of the eurasia africa nw se oblique convergence and other interacting processes like slab roll back or delamination however seismicity distribution and field observations reveal that most of the external mountain front of the betics is not clearly active at present and tectonic activity is generally concentrated towards

on the circulation and water masses over the antarctic continental slope and rise between 80 and 150 e abstract the circulation and water masses in the region between 80 and 150 e and from the antarctic continental shelf to the southern boundary of the antarctic circumpolar current acc 62 s are described from hydrographic and surface drifter data taken as part of the multi disciplinary experiment baseline research oceanography krill and the environment broke two types of bottom water are identified adelie land bottom water formed locally between 140 and 150 e and ross sea bottom water ross sea bottom water is found only at 150 e whereas adelie land bottom water is found throughout the survey region the bottom water mass properties become progressively warmer and saltier to the west suggesting a westward flow all of the eight meridional ctd sections show an antarctic slope front of varying strength and position with respect to the shelf break in the water formation areas between 140 and 150 e and 104 e the antarctic slope front is more v shaped while elsewhere it is one sided the shape of the slope front and the presence or absence of water formation there are consistent with other meridional sections in the weddel sea and simple theories of bottom water formation gill 1973 deep sea research 20 111 140 whitworth et al 1998 in jacobs and weiss eds ocean ice and atmosphere interactions at the antartic continental margin antarctic research series american geophysical union washington pp 1 27 adcp surface velocities and buoy drift tracks show a strong westward flow over the shelf and slope regions in the region 90 100 e there is a strong eastward flow of the waters just south of the southern boundary of the acc suggesting a recirculation of the westward slope current and the presence of a weak cyclonic gyre using the adcp velocities as a reference for the ctd data the average westward transport in this region is 29 4 14 7 sv

the chemistry of detrital chromian spinels and its implications for the geodynamic evolution of the eastern alps detrital chromian spinel is a key mineral in paleogeographic reconstructions the chemical compositions of the spinels provide even more specific information about their host ophiolites because their chemistry is related to the degree of melting of the mantle peridotite and thus to the geotectonic environment of ocean crust formation

berriasian drowning of the plassen carbonate platform at the type locality and its bearing on the early eoalpine orogenic dynamics in the northern calcareous alps austria the plassen carbonate platform kimmeridgian to early berriasian developed above the callovian to tithonian carbonate clastic radiolaritic flysch basins of the northern calcareous alps during a tectonically active period in a convergent regime remnants of the drowning sequence of the plassen formation have been discovered at mount plassen in the austrian salzkammergut it is represented by calpionellid radiolaria wacke to packstones that due to the occurrence of calpionellopsis oblonga cadisch are of late berriasian age oblonga subzone thus the plassen formation at its type locality shows the most complete profile presently known documenting the carbonate platform evolution from the initial shallowing upward evolution in the kimmeridgian until the final berriasian drowning the shift from neritic to pelagic sedimentation took place during berriasian times a siliciclastic influenced drowning sequence sealed the highly differentiated plassen carbonate platform the former interpretation of a late jurassic carbonate platform formed under conditions of tectonic quiescence cannot be confirmed the onset evolution and drowning of the plassen carbonate platform took place at an active continental margin the tectonic evolution of the northern calcareous alps during the kimmeridgian to berriasian time span and the reasons for the final drowning of the plassen carbonate platform are to be seen in connection with further tectonic shortening after the closure of the tethys ocean

circumpolar response of southern ocean eddy activity to a change in the southern annular mode 1 analysis of satellite altimeter data reveals anomalously high eddy kinetic energy eke in the antarctic circumpolar current acc during the period 2000 2002 around 2 3 years earlier 1998 the circumpolar eastward wind stress as quantified by the southern annular mode sam showed a significant positive peak and we have shown previously that the acc peaked around 1998 in response an eddy resolving ocean model is used to investigate the delay between wind forcing and the eddy response and demonstrates that the lag is due to the time taken to influence the deep circulation of the acc winds over the southern ocean have shown a strong climatic increase over the past few decades if this increase in winds is also reflected as an increase in eddy activity as our analysis suggests it might then the increased poleward heat flux may have played a significant role in the observed warming of the southern ocean citation meredith m p and a m hogg 2006 circumpolar response of southern ocean eddy activity to a change in the southern annular mode geophys res lett 33 l16608 doi 10 1029 2006gl026499

southern ocean mixed layer depth from argo float profiles 1 argo float profiles of temperature salinity and pressure are used to derive the mixed layer depth mld in the southern ocean mld is determined from individual profiles using both potential density and potential temperature criteria and a monthly climatology is derived from individual mlds using an objective mapping method quantitative data are available in the auxiliary material the spatial structures of mlds are similar in each month with deep mixed layers within and just north of the antarctic circumpolar current acc in the pacific and indian oceans the deepest mixed layers are found from june to october and are located just north of the acc where antarctic intermediate water aaiw and subantarctic mode water samw are formed examination of individual mlds indicates that deep mixed layers mld 400 m from both the density and temperature criteria are concentrated in a narrow surface density band which is within the density range of samw the surface salinity for these deep mixed layers associated with the samw formation are slightly fresher compared to historical estimates differences in air sea heat exchanges wind stress and wind stress curl in the pacific and indian oceans suggest that the mode water formation in each ocean basin may be preconditioned by different processes wind mixing and ekman transport of cold water from the south may assist the samw formation in the indian ocean in the eastern pacific the formation of mode water is potentially preconditioned by the relative strong cooling and weak stratification from upwelling

provenance of cretaceous synorogenic sandstones in the eastern alps constraints from framework petrography heavy mineral analysis and mineral chemistry abstract the detrital components of cretaceous sedimentary rocks in the northern calcareous alps reflect the early alpine geodynamic evolution of the austroalpine microplate two contrasting source areas are distinguished on the base of light and heavy mineral analysis the first source area is located at the southeastern margin of the austroalpine and is composed of palaeozoic sediments and metamorphic rocks mesozoic carbonate rocks and ultrabasic rocks derived from the suture zone of the vardar meliata ocean the second source area is located in the northwest in a lower austroalpine position near the transpressive plate margin that juxtaposes austroalpine and penninic units this source area comprises palaeozoic low grade metamorphic rocks including high pressure hp rocks late palaeozoic meta sediments mesozoic carbonate rocks and ultrabasic rocks from obducted slices of penninic oceanic crust chemical analyses of detrital white mica amphibole and garnet support the discrimination between the two source areas tourmaline chemistry calls for a significant amount of metasedimentary rocks in the source area granitoid rocks and high grade metamorphic rocks are rare blue amphibole phengite and chloritoid composition suggest the erosion of lower blueschist facies rocks in the northwestern source area we suggest a modified model of austroalpine valanginian to coniacian tectono sedimentary evolution which is based on 1 an onset of subduction of the penninic ocean no earlier than late cretaceous 2 deposition of the analyzed sedimentary rocks in piggyback basins and 3 a reconstruction of provenance as proposed in this study

evaluating southern ocean carbon eddy pump from biogeochemical argo floats the vertical transport of surface water and carbon into ocean s interior known as subduction is one of the main mechanisms through which the ocean influences earth s climate new instrumental approaches have shown the occurrence of localized and intermittent subduction episodes associated with small scale ocean circulation features these studies also revealed the importance of such events for the export of organic matter the so called eddy pump however the transient and localized nature of episodic subduction hindered its large scale evaluation to date in this work we present an approach to detect subduction events at the scale of the southern ocean using measurements collected by biogeochemical autonomous floats bgcargo we show how subduction events can be automatically identified as anomalies of spiciness and apparent oxygen utilization aou below the mixed layer using this methodology over more than 4 000 profiles we detected 40 subduction events unevenly distributed across the sothern ocean events were more likely found in hot spots of eddy kinetic energy eke downstream major bathymetric features moreover the bio optical measurements provided by bgcargo allowed measuring the amount of particulate organic carbon poc being subducted and assessing the contribution of these events to the total downward carbon flux at 100 m ep100 we estimated that the eddy pump represents less than 19 to the ep100 in the southern ocean although we observed particularly strong events able to locally duplicate the ep100 this approach provides a novel perspective on where episodic subduction occurs that will be naturally improved as bgcargo observations continue to increase

thermohaline stratification below the southern ocean sea ice the end of winter stratification within the cold cyclonic trough of the weddell gyre near 60 s between 5 e and the greenwich meridian is resolved with the mikhail somov data set the temperature maximum of the weddell deep water wdw is for the most part less than 0 5 c but warmer cells of wdw are found these warm wdw cells have temperature salinity and oxygen properties similar to the wdw characteristic of the weddell gyre inflow which is situated to the southeast of the mikhail somov study region the warm wdw cells are accompanied by domes in the pycnocline of 40 m amplitude over the surrounding pycnocline while deeper isopycnals are depressed anticyclonic shear below the 27 83 isopycnal within the warm wdw cells is compensated by the cyclonic shear associated with the pycnocline dome the pycnocline domes are exposed to about 50 greater entrainment by the turbulently active winter mixed layer relative to the regional entrainment rate this entrainment can significantly erode the warm cells in a single winter season introducing excess heat and salt into the mixed layer while the heat is lost to the atmosphere the excess salt is not necessarily compensated by increased fresh water introduction it is hypothesized that the warm wdw cells within the weddell gyre trough are derived from instability within the frontal zone which extends from maud rise to the northeast separating the weddell warm regime from the cold regime greater than normal injection of warm wdw cells into the weddell gyre trough would increase the surface salinity which would tend to destabilize the pycnocline increasing the probability of deep convection and polynya events

gully erosion impacts factors and control gully erosion attracts increasing attention from scientists as reflected by two recent international meetings poesen and valentin eds catena 50 2 4 87 564 li et al 2004 gully erosion under global change sichuan science technology press chengu china 354 pp this growing interest is associated with the increasing concern over off site impacts caused by soil erosion at larger spatial scales than the cultivated plots the objective of this paper is to review recent studies on impacts factors and control of gully erosion and update the review on dgully erosion and environmental change importance and research needst poesen et al 2003 catena 50 2 4 91 134 for the farmers the development of gullies leads to a loss of crop yields and available land as well as an increase of workload i e labour necessary to cultivate the land gullies can also change the mosaic patterns between fallow and cultivated fields enhancing hillslope erosion in a feedback loop in addition gullies tend to enhance drainage and accelerate aridification processes in the semi arid zones fingerprinting the origin of sediments within catchments to determine the relative contributions of potential sediment sources has become essential to identify sources of potential pollution and to develop management strategies to combat soil erosion in this respect tracers such as carbon nitrogen the nuclear bomb derived radionuclide 137 cs magnetics and the strontium isotopic ratio are increasingly used to fingerprint sediment recent studies conducted in australia china ethiopia and usa showed that the major part of the sediment in reservoirs might have come from gully erosion gullies not only occur in marly badlands and mountainous or hilly regions but also more globally in soils subjected to soil crusting such as loess european belt chinese loess plateau north america and sandy soils sahelian zone north east thailand or in soils prone to piping and tunnelling such as dispersive soils most of the time the gullying processes are triggered by

intensive water content and discharge measurement system in a hillslope gully in china abstract an automatic monitoring system was constructed to intensively study the water profile runoff interactions during rain events of a hillslope gully the system was installed on the loess plateau in the shaanxi province in northern china the primary goal was to obtain a better understanding of soil erosion processes in this district to aid in better management to accomplish this infiltration and runoff data for running calibrating and validating the lisem erosion model was needed the system presented here consisted of 29 time domain reflectometry tdr water content sensors that monitored the water content variation in time sensors were installed in different subsystems throughout the gully geometry such as in the cropland surrounding the gully in some gully slopes and in the gully floor at the outflow point of the gully an h flume was installed in order to measure the actual discharge of the gully system and to measure directly the sediment concentration in the discharge the monitoring system was programmed in this way so that more measurements were recorded when a rainstorm occurred installation took place in april 1998 and it was used until september 2000 in 1998 five major rain events were recorded which generated runoff and erosion in 1999 and 2000 only one cropland measurements showed high water contents and high infiltration rates all through the measuring period and also showed a strong reaction to precipitation the sidewalls of the gully showed much lower water contents where only very shallow parts showed some infiltration during rain showers while steep parts of the gully such as pipes and vertical walls showed an extremely low water content and practically no water content variation with time simulation results confirmed the suspicion that these areas are an important source for hortanian overland flow within the gully system model simulations further showed that most of the sediment being eroded from the gully system was coming from rills and smaller gullies being cut into the main gully bottom saturation excess overland flow proved to be dependent on the characteristic of the rain event as well as on the water content of the soil at the beginning of the event

multidecadal warming of subsurface temperature in the indian sector of the southern ocean 1 long term variations of subsurface layer temperature were examined for 32 years 1966 1998 of continuous observations in the indian sector of the southern ocean the data analyzed consist of observations from japanese antarctic research expeditions and also from other countries significant warming trends of about 0 004 c yr 1 were observed at all depths from 200 to 900 m to the north of the southern antarctic circumpolar current acc front orsi et al 1995 the rates of warming increase with increasing depth from 0 003 c yr 1 at 200 m to 0 012 c yr 1 statistically significant at 900 m in the region close to the front these warming trends were also found after applying a technique to correct for differences in the data sampling locations the warming tendency in the frontal region is consistent with the assumption of a southward shift of the front and may have a relationship with the observed retreat of sea ice edge

topographic influence on submesoscale dynamics in the southern ocean topography influences the circulation in the southern ocean generating stationary meanders in the lee of topographic features triggering hot spots of mesoscale eddy kinetic energy and modifying jets and fronts however the relationship between topography and submesoscale flows with length scales of order 1 10 km has not yet been explored the first submesoscale resolving 1 80 resolution ocean model with realistic topography of the indian sector of the southern ocean is used to investigate this interaction the results show spatial inhomogeneity in submesoscale activity that is correlated with topography topographic influence is primarily indirect topography controls mesoscale flows which in turn generate submesoscale activity mesoscale eddy kinetic energy and strain rate can be used to first order to infer submesoscale vertical velocity implying a possible route to parameterise submesoscale activity in coarser resolution models

initial value predictability of antarctic sea ice in the community climate system model 3 1 we assess initial value predictability characteristics of antarctic sea ice from climate simulations the integrations are initialized on 1 january with identical ice ocean terrestrial conditions and integrated forward for two years we find that the initialized ice ocean state provides predictive capability on the ice edge location around antarctica for the first several months of integration during the ice advance season from april to september significant predictability is retained in some locations with an eastward propagating signal this is consistent with previous work suggesting the advection of sea ice anomalies with the mean ocean circulation the ice edge predictability is then generally lost during the ice retreat season after october however predictability reemerges during the next year s ice advance starting around june in some locations this reemergence is associated with ocean heat content anomalies that are retained at depth during the austral summer and resurface during the following autumn as the ocean mixed layers deepen

the circulation and water masses of the antarctic shelf and continental slope between 30 and 80 e abstract the circulation and water masses from the antarctic continental shelf to 62 s between 30 and 80 e are described using hydrographic data collected on seven hydrographic sections during the baseline research on oceanography krill and the environment west broke west experiment the eastern limb of the weddell gyre dominates circulation between 30 and 40 e and is significantly cooler and fresher than the region to the east the antarctic circumpolar current acc extends from the north into the survey region east of 40 e reaching as far south as 65 5 s at 60 e this results in increasing observed maximum temperature and salinities progressively towards the east peaking at 80 e due to the intrusion of the southern acc front saccf to 63 s this southward extension is steered by the southern end of kerguelen plateau causing a horizontal shear of over 0 15 m s 1 between the eastward acc and westward flowing antarctic slope current asc the asc is observed at all six meridional sections immediately north of the shelf break it is strongly barotropic and transports a total of 15 8 7 4 sv westwards while the bottom referenced baroclinic component only contributes 1 3 0 3 sv at each section this current intensifies to a narrow westward jet with absolute velocities up to 0 3 m s 1 over the steepest shelf slope gradients at 70 e a v shape is observed in the asf this and the nearby presence of denser shelf water and ice shelf water is characteristic of antarctic bottom water aabw formation but no new aabw is found on this section instead significantly warmer saltier and less oxygenated aabw to the east and newly formed aabw high on the continental slope immediately to the west suggest a formation region just west of 70 e this newly formed aabw progressively becomes warmer and saltier west of 60 e and is observed extending offshore and moving westward below eastward flowing water masses acc frontal positions are found to be 1 2 farther north in the survey region than suggested by historical climatology

a method for dendrochronological assessment of medium term gully erosion rates abstract a method based on dendrochronology to estimate gully erosion rates was developed as an alternative of traditional methods for assessing medium term gully retreat rates such as field monitoring of headcuts or aerial photo interpretation of gully retreat the method makes use of trees or parts of a tree affected by gully erosion revealing information on the history of the erosion process by datable deviations of their normal growth pattern hence defined as datable objects these include roots exposed by erosion browsing scars made by ungulates on exposed roots or on above ground parts of fallen trees exposed and dead root ends root suckers stems branches and leading shoots of fallen trees and a sequence of trees within a gully the method is based on the differentiation between three main conditions depending on the relation between the dynamics of the datable object part of the tree and the development of the gully the first condition implies that the datable object was created before erosion of the gully volume to be dated e g exposed tree roots according to the second condition the datable object developed as an immediate consequence of the erosion event e g growth reactions of a fallen tree the third condition implies that the datable object was created some time after the erosion event took place e g trees colonising the gully bed each principle has consequences for the accuracy and the correct interpretation of the estimated erosion rate i e whether the true erosion rate is underestimated exact or overestimated in spite of methodological limitations and dendrochronological dating problems the method was successfully applied in southeast spain conservative estimations of gully head retreat rate resulted in an average medium term 3 46 years value of 6 m3 year 1 n 9 for gully sidewall processes the average minimum erosion rate per unit sidewall length amounted 0 1 m3 year 1 m 1 n 9 a strong correlation was found between the headcut retreat rate vm ortho m3 year 1 and the drainage basin area a m2 of the gullies expressed by vm ortho 0 02a0 57 r2 0 93 n 9 comparing the findings from this study with those obtained by short term headcut retreat monitoring suggests a high reliability of the estimated retreat rates supporting the applicability of the developed dendrochronological method

subduction tectonic erosion and late cretaceous subsidence along the northern austroalpine margin eastern alps austria abstract the late cretaceous to early tertiary subsidence history of the northern calcareous alps nca records the effect of two independent basin formation mechanisms at the northern leading margin of the austroalpine unit the terrestrial to shallow marine sediments of the lower gosau subgroup were deposited mainly within small fault bound basins during a phase of strike slip faulting from the late turonian onwards after a short period of uplift deformation and erosion of 1 to 3 ma renewed rapid subsidence followed during this period the whole nca subsided into bathyal to abyssal depths the characteristics of this second evolutionary phase are 1 a short period of uplift and erosion followed by strong subsidence of the whole nca with tectonic subsidence rates up to 700 m ma 2 sedimentation of turbidites and hemipelagites upper gosau subgroup 3 northward tilting of the depositional area 4 elimination of an accretionary wedge north of the nca as the main source for the sediments and 5 a pronounced migration of the subsidence event from the northwest to the southeast from late turonian santonian to the maastrichtian these features can be explained by a model of subduction tectonic erosion along the northern margin of the austroalpine unit a part of the adriatic microplate tectonic erosion as compared to recent analogues and fore arc modelling may be due to the collision and oblique subduction of an oceanic swell or ridge of the penninic plate beneath the overriding austroalpine unit with the nca on its leading northern margin

ice shelf water overflow and bottom water formation in the southern weddell sea 1 cold shelf waters flowing out of the filchner depression in the southern weddell sea make a significant contribution to the production of weddell sea bottom water wsbw a precursor to antarctic bottom water aabw we use all available current meter records from the region to calculate the flux of cold water 1 9 c over the sill at the northern end of the filchner depression 1 6 0 5 sv and to determine its fate the estimated fluxes and mixing rates imply a rate of wsbw formation referenced to 0 8 c of 4 3 1 4 sv we identify three pathways for the cold shelf waters to enter the deep weddell sea circulation one path involves flow constrained to follow the shelf break the other two paths are down the continental slope resulting from the cold dense water being steered northward by prominent ridges that cross the continental slope near 36 w and 37 w mooring data indicate that the deep plumes can retain their core characteristics to depths greater than 2000 m probably aided by thermobaricity the plume water at this depth can flow at a speed approaching 1 m s 1 implying that the flow is occasionally supercritical we postulate that such supercriticality acts to limit mixing between the plume and its environment the transition from supercritical to slower more uniform flow is associated with very efficient mixing probably as a result of hydraulic jumps

plate tectonics and pelagic facies late jurassic to early cretaceous deep sea sediments of the ybbsitz ophiolite unit eastern alps austria abstract pelagic sediments of the ybbsitz unit are part of an ophiolite sequence within the penninic unit in the eastern alps cherts and calpionellid limestones of late jurassic to early cretaceous age were deposited on oceanic basement sedimentation near an oceanic spreading center below the calcium compensation depth ccd is represented by chert clay rhythmites cherts display hydrothermal fe and mn mineralizations that are characterized by low contents of co ni and cu as well as by high fe2o3 tio2 and mno tio2 ratios as the site of deposition migrated away from the spreading center hydrothermal influence ceased due to the late jurassic drop of the ccd calcareous radiolarian ooze was deposited on intrabasinal topographic heighs downslope transport of this ooze to sites below the ccd by turbidity currents resulted in intercalations of calcareous and carbonate free sediments apparently the drop of the ccd was greater than the rate of cooling induced basement subsidence as calcareous radiolarites overly this sequence carbonate contents gradually increase upsection and micritic limestones terminate purely pelagic sedimentation at the jurassic cretaceous boundary plate drift moved the site of deposition towards an active continental margin producing a coarsening upward clastic sequence this sequence starts with turbidite and breccia intercalations in pelagic limestones followed by the deposition of early cretaceous flysch it marks the onset of subduction of the ybbsitz unit under the austroalpine continental margin

the response of the southern ocean and antarctic sea ice to freshwater from ice shelves in an earth system model abstractthe possibility that recent antarctic sea ice expansion resulted from an increase in freshwater reaching the southern ocean is investigated here the freshwater flux from ice sheet and ice shelf mass imbalance is largely missing in models that participated in phase 5 of the coupled model intercomparison project cmip5 however on average precipitation minus evaporation p e reaching the southern ocean has increased in cmip5 models to a present value that is about greater than preindustrial times and 5 22 times larger than estimates of the mass imbalance of antarctic ice sheets and shelves 119 544 two sets of experiments were conducted from 1980 to 2013 in cesm1 cam5 one of the cmip5 models artificially distributing freshwater either at the ocean surface to mimic iceberg melt or at the ice shelf fronts at depth an anomalous reduction in vertical advection of heat into the surface mixed layer resulted in sea surface cooling at high southern latitudes and an associated increase in sea i