climatic controls on late pleistocene alluvial fans cyprus alluvial fans are commonly associated with tectonically active mountain ranges and tectonism is frequently held responsible for abrupt coarsening and cyclical sedimentation of alluvial fan sequences whilst it is accepted that tectonism provides the opportunity for alluvial fan development through the creation of topography increasing gradients of fluvial systems supplying sediments and creating accommodation for the storage of sediment flux the role of climate in fan development is frequently neglected the hypothesis that climatically controlled events can produce recognisable sedimentary signatures in alluvial fan deposits is tested in the active supra subduction zone setting of the late pleistocene of southern cyprus this study demonstrates through architectural analysis and the reconstruction of palaeoflood hydrology a recorded pattern of increasing and decreasing palaeoflow dynamics with switches from a wetter to drier mode clearly exhibited by changes in the sedimentology of the fan at the present day cyprus has a semi arid climate and is influenced by a strongly seasonal rainfall pattern largely restricted to the winter months plus rare occurrences of summer cyclones however at precession minima increased activity of western mediterranean depressions produces wetter summers using inference we propose that longer term increases in rainfall increased river discharge as recorded in the fan palaeoflood hydrology and occurred at minima in the precession these periods correlate with the deposition of conglomeratic channels and open framework gravels drier periods are exhibited by sandier braided fluvial deposits shorter term or seasonal change is recorded in the form of 2nd and 3rd low order bounding surfaces this increased activity of mediterranean summer depressions increased precipitation to the wider levantine area and was coincident with increased intensity of the north african and indian ocean sw monsoons the resultant increase in river discharges at precession minima from both the nile and the wider levant resulted in the formation of sapropels in the eastern mediterranean and is recorded as wet periods in speleothem deposits in the soreq and peqiin caves of israel the predominant control of sedimentation on the late pleistocene alluvial fans of southern cyprus was climate

land ice elevation changes from photon counting swath altimetry first applications over the antarctic ice sheet satellite altimetric time series allow high precision monitoring of ice sheet mass balance understanding elevation changes in these regions is important because outlet glaciers along ice sheet margins are critical in controlling flow of inland ice here we discuss a new airborne altimetry dataset collected as part of the icecap international collaborative exploration of the cryosphere by airborne profiling project over east antarctica using the alamo airborne laser altimeter with mapping optics system of a scanning photon counting lidar combined with a laser altimeter we extend the 2003 09 surface elevation record of nasa s icesat satellite by determining cross track slope and thus independently correcting for icesat s cross track pointing errors in areas of high slope cross track errors result in measured elevation change that combines surface slope and the actual z t signal slope corrections are particularly important in coastal ice streams which often exhibit both rapidly changing elevations and high surface slopes as a test case assuming that surface slopes do not change significantly we observe a lack of ice dynamic change at cook ice shelf while significant thinning occurred at totten and denman glaciers during 2003 09

fluvial responses to tectonics and climate change during the late weichselian in the eastern part of the pannonian basin hungary abstract fine grained sandy silty channel belt and floodplain deposits of the berettyo koros rivers a main eastern transverse tributary system of the modern tisza river in the eastern part of the pannonian basin were deposited during the late pleistocene under net subsiding conditions the palaeo drainage network pattern of a 2500 km 2 large part of the alluvial plain was reconstructed based on interpretation of airborne photographs and analysis of 18th century topographic maps which show the natural river patterns that predate the introduction of river regulation schemes the investigation showed that a large meandering river system with two main channel belts surrounding a floodbasin entered the alluvial plain from the northeast and a braided river entered the alluvial plain from the southeast detailed sedimentary logs of seven continuous corings and several sand and clay pit sections were used to characterize different alluvial units optical luminescence dating osl of 25 quartz samples and four 14 c datings showed that the sediments are of late pleniglacial to late glacial age transport directions inferred from heavy mineral analyses combined with the osl ages strongly suggest that the large meandering system represents the palaeo tisza river which supposedly flowed along the northeast southwest striking ermellek depression during the late pleniglacial the braided river can be regarded as a precursor to the fekete and feher koros rivers which entered the alluvial plain from the southeast during the late glacial the interpretation of seismic profiles field measurements of neotectonic activity and variations in thickness of sediments along the studied profile revealed that river development was largely controlled by subsidence along the ermellek depression until 14 to 16 ky and by uplift of the southeastern part of the catchment area the studied fluvial successions also document the response of the palaeo tisza and koros system to the climate changes of the weichselian late pleniglacial late glacial period much of the sand from the meandering zones was deposited during the bolling allerod and sagvar lascaux interstadials whereas some dated sand units from the braided zone represent the older and younger dryas the error ranges of osl dates which often exceed the duration of weichselian substages and subdivisions prevented an unambiguous correlation of the studied sections with the millennial scale climate changes of the last 25 ky meandering and braided river activity coexisted under different climate conditions whereas locations of the main channel belts are related to subsidence anomalies the results of our study thus clearly indicate that tectonics was the primary control on river development

relative roles of elevated heating and surface temperature gradients in driving anomalous surface winds over tropical oceans abstract elevated heating by cumulus convection and sea surface temperature gradients are both thought to contribute to surface winds over tropical oceans the relative strength and role of each mechanism is examined by imposing forcing derived from data on a linear primitive equation model with idealized parameterizations for the two forcings and comparing the response with observed surface winds two test cases are studied one related to the el nino southern oscillation and the other related to the dipole mode in the tropical atlantic it is found that in both cases elevated heating dominates the surface zonal wind response and contributes significantly to the meridional wind response especially in the subtropics and the south pacific and south atlantic convergence zone regions surface temperature gradients dominate the meridional wind forcing in regions near the equator with strong meridional temperature gradients

vertical motion and diabatic heating over the indian monsoon region during the bay of bengal depression of 5 8 july 1979 the vertical velocity and the diabatic heating were computed at 800 600 400 and 200 mb surfaces using the omega equation the highest contribution to is from the diabatic heating produced by condensation associated with the precipitations appearing to be the main source of diabatic heating the net radiative cooling and the thermal advection in the upper troposphere over the warm anticyclone result in diabatic cooling over the eastern part of the bay of bengal and adjoining northern and eastern regions

analysis techniques for coherent airborne radar sounding application to west antarctic ice streams 1 analysis of coherent radar sounding echoes from polar ice sheets can provide information suitable for classifying the subglacial environment echoes from a general interface consist of both specularly reflected and diffusely scattered contributions specular reflection results from smooth uniform interfaces whereas diffuse scattering results from rough nonuniform interfaces and inhomogeneous media this article discusses how these phenomena are important to the acquisition and analysis of coherent radar sounding data reflection results are presented from airborne surveys conducted in 1987 over the downstream portions of whillans ice stream and ice stream c west antarctica additionally reflection and scattering analyses along with new results are presented for repeat profiles flown in 2001 over ice stream c analysis methods include using echo amplitudes to compute reflection coefficients which are used for inferring the dielectric properties of the subglacial material echo phase analysis provides the locations of dominant scattering centers which relate to reflection or scattering from the interface as well as provide interface roughness estimates comparison of low and high resolution imaging obtained from synthetic aperture radar techniques indicates a reflecting and or scattering interface combining the results from these independent analyses provides classification of the subglacial environment classified regions include smooth seawater smooth saturated sediments accreted marine ice rough bottom crevasses mixed conditions with partial subglacial water and dry frozen conditions

causes of recent himalayan uplift deduced from deposited patterns in the ganges basin the hypothesis1 that late cenozoic uplift of many of the world s mountain ranges was a response to climate change rather than to tectonic processes is based on the premise that enhanced erosion in an altered climate led to a reduction in both the total mass of a mountain range and its mean elevation this reduction was coeval with increased regional relief and with passive isostatic uplift of the remaining summits the hypothesis is difficult to evaluate because both climate and tectonic forces affect uplift in many active ranges in the absence of sufficient denudational and uplift data from the mountains themselves depositional patterns in adjacent basins may sometimes be used to distinguish between uplift arising from erosional or from tectonic processes in foreland basins uplift of the proximal basin and a reduction or absence of asymmetric subsidence are predicted responses to erosionally driven uplift2 here i show that patterns of sediment accumulation and the position of major rivers in the neogene gangetic foreland basin seem to have changed markedly in plio pleistocene times these changes lend support to the hypothesis that the importance of erosional unloading has increased in the himalayas during the past 4 myr

zonal and vertical structure of the madden julian oscillation abstract a statistical study of the three dimensional structure of the madden julian oscillation mjo is carried out by projecting dynamical fields from reanalysis and radiosonde data onto space time filtered outgoing longwave radiation olr data mjo convection is generally preceded by low level convergence and upward motion in the lower troposphere while subsidence cooling and drying prevail aloft this leads to moistening of the boundary layer and the development of shallow convection followed by a gradual and then more rapid lofting of moisture into the middle troposphere at the onset of deep convection after the passage of the heaviest rainfall a westerly wind burst region is accompanied by stratiform precipitation where lower tropospheric subsidence and drying coincide with continuing upper tropospheric upward motion the evolution of the heating field leads to a temperature structure that favors the growth of the mjo the analysis also reveals distinct differences in the vertical structure

a possible new mechanism for northward propagation of boreal summer intraseasonal oscillations based on trmm and merra reanalysis boreal summer intraseasonal oscillations bsisos manifest in the active and break spells and act as the primary building block of the indian summer monsoon although recent research has evolved a basic framework for understanding the scale selection and northward propagation of the bsiso the role of different hydrometeors in modulating these processes remains poorly explored in this study trmm 2a12 retrievals and modern era retrospective analysis for research and applications reanalysis data are examined to establish relationship between cloud hydrometeors and other atmospheric dynamical parameters with the northward propagation of the bsisos the study reveals that the cloud liquid water leads the deep convection during the northward propagation of bsisos in the lower troposphere while the cloud ice slightly lags the convection this distribution indicates the occurrence of a possible mechanism of the lower level moistening through the large scale moisture advection in lower atmosphere and boundary layer pbl convergence followed by triggering of the deep convection the analyses of moisture advection and the dynamical fields with respect to the convection center show that low level moistening is a manifestation of the barotropic vorticity and pbl convergence of moisture anomaly north of the convection center a new internal dynamical thermodynamical mechanism is unraveled to understand the reason behind the middle tropospheric heating maximum and its role on the northward propagation it is shown that the enhanced moisture perturbation in lower levels together with the heat transport by the sub grid scale eddies within the pbl induces lower level instability required to precondition the lower atmosphere for triggering the deep convection vigorous upward motion inside the deep convection uplifts the liquid hydrometeors to upper levels and the formation of precipitable ice leads to the heating maxima in the middle troposphere to check the robustness of the proposed hypothesis similar analysis is performed for the weak northward propagating bsiso cases

long term fluvial archives in hungary response of the danube and tisza rivers to tectonic movements and climatic changes during the quaternary a review and new synthesis abstract the paper discusses the quaternary evolution of the danube and tisza rivers and their main tributaries in the context of evolution of the entire pannonian basin which is europe s largest intramontane basin within the alp carpathian orogen the palaeo drainage reconstruction of the pannonian basin for the pre quaternary period is outlined in connection with the gradual regression of lake pannon since the late miocene deltas of rivers that entered the basin from the northwest and northeast were gradually transformed into extended alluvial plains thus the earliest possible ancestor of the danube coming southeastwards from the alps could be as old as late miocene by the pliocene the whole lake pannon was infilled the former extensional basin formation was replaced by a compresional stress field which resulted in an uplift of the marginal flanks and late stage subsidence anomalies the increasing relief led to the formation of the quaternary drainage pattern the actively subsiding young basins were filled by fluvial sediments transported by the danube and tisza river systems from the uplifting mountains between the subsiding regions of the little and great plains the danube has formed an antecedent valley with terrace staircases between the uplifting sections of the transdanubian range and the north midmountains the formation of the terraces is attributed to periodic climate changes during the pleistocene combined with differences in the uplift rate the paper gives a complex overview of the classical chronology of the six terraces based on various data sources mostly dating of loess paleosol sequences travertines aeolian sand and tephra strata overlying the fluvial sediments complemented by scattered vertebrate faunal data and archaeological evidence directly from the terrace sediments the quaternary drainage pattern evolution of the great plain with a strong tectonic control is discussed in detail rivers originating from the uplifting marginal areas were drawn towards the subsiding depressions which served as local base level changes in subsidence rates in space and time throughout the quaternary resulted in the evolution of a complex drainage pattern a special emphasis is placed on the late pleistocene holocene development of the middle tisza region and the koros basin where the berettyo koros rivers form an eastern tributary system of the tisza river a comparative evaluation of these two areas is especially relevant as they provide insights into large scale late pleistocene avulsion of the tisza river osl dating complemented with inferred transport directions determined from heavy mineral analysis of fluvial sediments in the koros basin has revealed an ancient large meandering river system that can be identified with the palaeo tisza which was flowing along a tectonically controlled depression during the late pleniglacial successions in the middle tisza region have allowed differentiation between the older channels of the palaeo bodrog river and the sajo hernad alluvial fan and the younger meander belts of the new course of the tisza in the tisza system changes in river style braided to various scales of meandering show correspondence to millennial scale climate changes of the last 25 ka while in the koros basin the effects of tectonics are overprinted onto the regional climatic signals

the messinian problem in the pannonian basin eastern hungary insights from stratigraphic simulations abstract earlier studies revealed a prominent unconformity in the messinian stratigraphic record of the lacustrine pannonian basin but it was unclear what factors were responsible for the formation of this unconformity and thus its origin remained controversial the problem was further complicated by the fact that stratal patterns in the messinian varied significantly along the paleo margins of the lake our study introduces quantitative stratigraphic simulations to analyze the role of subsidence sediment supply and lake level changes in the formation of the unconformity and the various architectural patterns that evolved in response to the messinian events the results suggest that a relative lake level fall occurred in the messinian accompanied and followed by tectonic inversion in several parts of the basin since the rate of tectonic subsidence and or uplift varied in space and time the size of the relative lake level fall varied significantly across the basin while various stratal architectural patterns formed in the same time interval the age of the unconformity was estimated based on seismic correlations with paleomagnetic chronozones to be between 5 6 ma which was refined by stratigraphic simulations galeacysta etrusca cysts were found in the unconformity which confirmed its late messinian age the surface is called the intra messinian unconformity imu in this paper seismic interpretations and simulations of stratal architecture led to the formulation of a basin fill model and identification of four stratigraphic architectural patterns related to messinian events including a major lake level fall and coeval and subsequent uplift events in certain parts of the basin

monsoon convection in the himalayan region as seen by the trmm precipitation radar three dimensional structure of summer monsoon convection in the himalayan region and its overall variability are examined by analyzing data from the tropical rainfall measuring mission trmm precipitation radar over the june september seasons of 2002 and 2003 statistics are compiled for both convective and stratiform components of the observed radar echoes deep intense convective echoes 40 dbz echo reaching heights 10 km occur primarily just upstream south of and over the lower elevations of the himalayan barrier especially in the northwestern concave indentation of the barrier the deep intense convective echoes are vertically erect consistent with the relatively weak environmental shear they sometimes extend above 17 km indicating that exceptionally strong updraughts loft graupel to high altitudes occasionally scattered isolated deep intense convective echoes occur over the tibetan plateau wide intense convective echoes 40 dbz echo 1000 km2 in horizontal dimension also occur preferentially just upstream of and over the lower elevations of the himalayas most frequently in the northwestern indentation of the barrier the wide intense echoes have an additional tendency to occur along the central portion of the himalayas and they seldom if ever occur over the tibetan plateau the wide intense echoes exhibit three mesoscale structures amorphous areas lines parallel to the mountain barrier and arc shaped squall lines perpendicular to and propagating parallel to the steep himalayan barrier the latter are rare generally weaker than those seen in other parts of the world and occur when a midlevel jet is aligned with the himalayan escarpment deep and wide intense convective echoes over the northwestern subcontinent tend to occur where the low level moist layer of monsoon air from the arabian sea meets dry downslope flow in a manner reminiscent of severe convection leeward of the rocky mountains in the central usa as the low level layer of moist air from the sea moves over the hot arid northwestern subcontinent it is capped by an elevated layer of dry air advected off the afghan or tibetan plateau the capped low level monsoonal airflow accumulates instability via surface heating until this instability is released by orographically induced lifting immediately adjacent to or directly over the foothills of the himalayas broad 50 000 km2 in area stratiform echoes occur in the eastern and central portions of the himalayan region in connection with bay of bengal depressions their centroids are most frequent just upstream of the himalayas in the region of the concave indentation of the barrier at the eastern end of the range the steep topography apparently enhances the formation and longevity of the broad stratiform echoes monsoonal depressions provide a moist maritime environment for the convection evidently allowing mesoscale systems to develop larger stratiform echoes than in the western himalayan region copyright 2007 royal meteorological society

radar absorption basal reflection thickness and polarization measurements from the ross ice shelf antarctica author s hanson jc barwick sw berg ec besson dz duffin tj klein sr kleinfelder sa reed c roumi m stezelberger t tatar j walker ja zou l abstract radio glaciological parameters from the moore s bay region of the ross ice shelf antarctica have been measured the thickness of the ice shelf in moore s bay was measured from reflection times of radio frequency pulses propagating vertically through the shelf and reflecting from the ocean and is found to be 576 8m introducing a baseline of 543 7m between radio transmitter and receiver allowed the computation of the basal reflection coefficient r separately from englacial loss the depth averaged attenuation length of the ice column l is shown to depend linearly on frequency the best fit 95 confidence level is l v 460 20 180 40 vm 20 db km 1 for the frequencies v 0 100 0 850 ghz assuming no reflection loss the mean electric field reflection coefficient is r 0 82 0 07 1 7db reflection loss across 0 100 0 850 ghz and is used to correct the attenuation length finally the reflected power rotated into the orthogonal antenna polarization is l5 below 0 400 ghz compatible with air propagation the results imply that moore s bay serves as an appropriate medium for the arianna high energy neutrino detector

dependence of simulation of boreal summer tropical intraseasonal oscillations on the simulation of seasonal mean the link between realism in simulation of the seasonal mean precipitation and summer tropical intraseasonal oscillations and their dependence on cumulus parameterization schemes is investigated using the florida state university global spectral model fsugsm forty member model ensemble simulations of the northern summer season are generated for three different cumulus parameterization schemes namely arakawa schubert naval research laboratory nrl zhang and mcfarlane national center for atmospheric research ncar and emanuel massachusetts institute of technology mit the mit scheme simulates the regional pattern of seasonal mean precipitation over the indian monsoon region well but has large systematic bias in simulating the precipitation over the western pacific and the maritime continent although the simulation of details of regional distribution of precipitation over the indian monsoon region by the nrl and ncar schemes is not accurate they simulate the spatial pattern of precipitation over the tropical indo pacific domain closer to observation the nrl scheme seems to captures the observed northward and eastward propagation of intraseasonal precipitation anomalies realistically however the simulations of the ncar and mit schemes are dominated by a westward propagating component the westward propagating mode seen in the model as well as observations is indicated to be an equatorial rossby wave modified by the northern summer mean flow an examination of the relationship between simulation of the model climatology and eastward propagating character of monsoon intraseasonal oscillations isos in a limited sample shows that the scheme that simulates better seasonal mean pattern of rainfall over the tropical indo pacific domain also simulates better intraseasonal variance and more realistic eastward propagation of monsoon isos among the parameters known to be important for meridional propagation of the summer monsoon isos the meridional gradient of mean humidity in the lower atmosphere seems to be crucial in determining the northward propagation in the equatorial indian ocean between 10 s and 10 n for better prediction of the seasonal mean indian monsoon therefore the model climatology should have minimum bias not only over the indian monsoon region but also over the entire indo pacific basin

chemical fractionation of brine in the mcmurdo ice shelf antarctica abstract during the austral summers of 1976 77 and 1978 79 several ice cores were taken from the mcmurdo ice shelf brine zone to investigate its thermal physical and chemical properties this brine zone consists of a series of superimposed brine layers waves that originate at the seaward edge of the ice shelf and migrate at various rates depending upon their age and position in the ice shelf the brine in these layers becomes increasingly concentrated as the waves migrate inland through the permeable ice shelf firn chemical analyses of brine samples from the youngest uppermost brine wave show that it contains sea salts in normal seawater proportions further inland deeper and older brine layers though slightly highly saline s200 are severely depleted in s04 2 na ratio being an order of magnitude less than that of normal seawater analyses of na k ca2 mg2 so4 2 and c1 together with solubility and temperature considerations show that the sulfate depletion is due to selective precipitation of mirabilite na2s041oh2o the location of the inland boundry of brine penetration is closely related to the depth at which the brine encounters the firn ice transition however a small but measurable migration of brine is still occurring in otherwise impermeable ice this is attributed to eutectic dissolution of the ice by concentrated brine as it moves into deeper and warmer parts of the mcmurdo ice shelf

multidecadal observations of the antarctic ice sheet from restored analog radar records airborne radar sounding can measure conditions within and beneath polar ice sheets in antarctica most digital radar sounding data have been collected in the last 2 decades limiting our ability to understand processes that govern longer term ice sheet behavior here we demonstrate how analog radar data collected over 40 y ago in antarctica can be combined with modern records to quantify multidecadal changes specifically we digitize over 400 000 line kilometers of exploratory antarctic radar data originally recorded on 35 mm optical film between 1971 and 1979 we leverage the increased geometric and radiometric resolution of our digitization process to show how these data can be used to identify and investigate hydrologic geologic and topographic features beneath and within the ice sheet to highlight their scientific potential we compare the digitized data with contemporary radar measurements to reveal that the remnant eastern ice shelf of thwaites glacier in west antarctica had thinned between 10 and 33 between 1978 and 2009 we also release the collection of scanned radargrams in their entirety in a persistent public archive along with updated geolocation data for a subset of the data that reduces the mean positioning error from 5 to 2 5 km together these data represent a unique and renewed extensive multidecadal historical baseline critical for observing and modeling ice sheet change on societally relevant timescales

vertical diabatic heating structure of the mjo intercomparison between recent reanalyses and trmm estimates abstractcapitalizing on recently released reanalysis datasets and diabatic heating estimates based on tropical rainfall measuring mission trmm the authors have conducted a composite analysis of vertical anomalous heating structures associated with the madden julian oscillation mjo because diabatic heating lies at the heart of prevailing mjo theories the intention of this effort is to provide new insights into the fundamental physics of the mjo however some discrepancies in the composite vertical mjo heating profiles are noted among the datasets particularly between three reanalyses and three trmm estimates a westward tilting with altitude in the vertical heating structure of the mjo is clearly evident during its eastward propagation based on three reanalysis datasets which is particularly pronounced when the mjo migrates from the equatorial eastern indian ocean eeio to the western pacific wp in contrast this vertical tilt in heating structure is not readily seen in the three trmm product

river profiles along the himalayan arc as indicators of active tectonics abstract longitudinal profiles along sixteen major transverse himalayan rivers add important constraints to models of active continental subduction and its evolution these profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases the base of the zone of increased gradients correlates with 1 the topographic front between the lesser and high himalayas 2 the narrow belt of intermediate magnitude thrust earthquakes 3 the main central thrust zone mct these features define a small circle in the central portion of the himalayan arc these correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising high himalayas and the lesser himalayas no sharp increases in gradient are observed near the main boundary thrust mbt except on a few rivers such as the jhelum or kundar where the mbt lies close to both the mct and the seismic belt thus it is unlikely that the mbt is a major tectonic boundary the diversion of river courses along the mbt and around anticlines in the sub himalayas has probably been caused by aggradation near the rosion deposition boundary upstream of uplifts in the mahabharat range and sub himalayas a parallel is drawn between the himalayas and new guinea based on the hypothesis that continent arc collision of the type occurring in northern australia preceded continent continent collision in the himalayas the present sedimentary tectonic phase in new guinea resembles the subathu paleocene eocene phase in the himalayas incipient counterparts of the major himalayan structures including the mct and the mbt are recognized in new guinea the drainage patterns in the himalayas and in new guinea bear a similar relation to major structures this suggests that 1 the tectonic evolution of the himalayas has been rather uniform since early stages of collision and 2 the himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the high himalayas

towards a mechanical model for the formation of the pannonian basin abstract new maps showing crustal and lithospheric thickness variations in the pannonian basin and the surrounding east alpine carpathian and dinaric mountains have been prepared on the basis of recent seismic seismologic and electromagnetic data a map presenting miocene faults of regional significance has been also constructed for the same region by using a wealth of recently available national and or more local studies it is suggested that observed crustal and lithospheric structural contrasts have been controlled primarily by neogene kinematic history of the region kinematic history is characterized by the following main patterns 1 1 indentation by adria and large scale backthrusting in the southern alps 2 2 eastward escape and extension of the eastern alps 3 3 extensional collapse in the pannonian basin area 4 4 formation of broad wrench fault systems along strike in the dinarides and southern carpathians and the western carpathians with dextral and sinistral shear respectively 5 5 compression and accretion of the external thrust and fold belt in the eastern carpathians these kinematic patterns are thought to be interrelated and all are manifestations of the late stage evolution of an overthickened orogenic wedge in order to arrive at a better understanding of the mechanism of extension which formed the pannonian basin deep crustal seismic profiles hydrocarbon exploration reflection lines and borehole data have been analyzed in the little hungarian plain this plain represents the transition zone between the alps and the pannonian lowlands and the results are illustrated by eight interpreted cross sections one result of regional importance is the clear recognition that the transdanubian central range at the southeastern flank of the little hungarian plain is composed of alpine pre senonian thrust sheets this finding marks the end of a century of debate the allochthony of the substrata of the pannonian basin can be now considered proven another result of more general interest is that these cross sections document the mode of lithospheric extension preexisting compressional detachment planes reactivate as low angle normal faults and lead to tectonic unroofing of deeply buried metamorphic terranes characterized by ductile flow along subhorizontal lineation

space time structure of diabatic heating in monsoon intraseasonal oscillation abstractthe space time structure of the leading monsoon intraseasonal oscillation miso in three dimensional diabatic heating is studied using the era interim data of the european centre for medium range weather forecasts the diabatic heating data were constructed by the residual method of the thermodynamic equation the miso was extracted by applying multichannel singular spectrum analysis on the daily anomalies of three dimensional diabatic heating over the south asian monsoon region for the period 1979 2011 the diabatic heating miso has a period of 45 days and exhibits eastward propagation in the equatorial indian and pacific oceans and northward propagation over the entire monsoon region the horizontal structure shows a long tilted band of heating anomalies propagating northeastward the period horizontal pattern and propagation properties of the diabatic heating miso are similar to those found in precipitation outgoing longwave radiation and circulation in earlier studies the vertical struc

a moist linear baroclinic model coupled dynamical convective response to el nino a newly developed linear baroclinic model lbm and its application to the tropical enso teleconnection is described the model based on primitive equations linearized about the observed zonally varying basic state in northern winter involves linear schemes for the cumulus convection and surface sensible and latent heat fluxes referred to as the moist lbm this enables us to solve a steady state response of the coupled dynamical convective system to a given sst anomaly which is fairly different from the conventional dry lbm linear representation of the convection is acceptable for a realistic range of sst anomalies reproducing well the rossby wave train computed in the conventional lbm forced by a tropical heating the moist lbm is used to examine the formation mechanisms of an anomalous low level anticyclone near

the subglacial geology of wilkes land east antarctica wilkes land is a key region for studying the configuration of gondwana and for appreciating the role of tectonic boundary conditions on east antarctic ice sheet eais behavior despite this importance it remains one of the largest regions on earth where we lack a basic knowledge of geology new magnetic gravity and subglacial topography data allow the region s first comprehensive geological interpretation we map lithospheric domains and their bounding faults including the suture between indo antarctica and australo antarctica furthermore we image subglacial sedimentary basins including the aurora and knox subglacial basins and the previously unknown sabrina subglacial basin commonality of structure in magnetic gravity and topography data suggest that pre eais tectonic features are a primary control on subglacial topography the preservation of this relationship after glaciation suggests that these tectonic features provide topographic and basal boundary conditions that have strongly influenced the structure and evolution of the eais

climatic and tectonic controls on fluvial incision and aggradation in the spanish pyrenees the influences of tectonic and climatic changes on upland river systems are investigated using data from plio pleistocene terraces of the rio cinca river in the southern pyrenees this river runs transverse to the main thrust fault structures and is a major conduit for sediment delivery to the ebro basin detailed field mapping combined with long profile and palaeohydraulic reconstructions yields a comprehensive picture of changes in palaeoriver character during the plio pleistocene as the area is over 150 km from the basin outlet in the mediterranean sea changes in base level are unlikely to have influenced terrace development although tectonic activity has exerted a strong control on the position of the river the main period of thrust propagation pre dates the terraces and activity has waned from the pliocene through to the present it is concluded that the main control on incision in this area is climate through its influence on sediment supply rivers which are starved of sediment by climate change will have the power to incise whereas aggradational phases are linked to periods of increased sediment flux

atmosphere ocean thermal coupling in the north atlantic a positive feedback in this article it is examined whether a positive atmosphere ocean feedback is found over the north atlantic through a series of general circulation model gcm experiments a 60 year integration of an atmospheric gcm agcm coupled with a 50 m deep motionless ocean was conducted the coupled run was compared with two uncoupled runs one with prescribed mid latitude climato logical sea surface temperatures ssts and the other with daily ssts derived from the coupled experiment the uncoupled atmosphere forces the slab ocean to obtain sst responses in these runs consistent with previous studies the coupled atmosphere ocean fields show interannual variances larger than those in the uncoupled runs due to reduction in the local thermal damping patterns of maximum atmosphere ocean covariability show the north atlantic oscillation nao and tripole sst anomalies both in the coupled and uncoupled fields indicating a dominant role of the atmosphere in generating the sst anomalies on the other hand analyses of the temporal variability in the three runs suggest an active role of sst anomalies in determining the polarity of the air sea coupled variability longer than the interannual time scale a combined analysis of forcing sst upper air height and the response sst anomalies in the uncoupled run identified that a patch of positive sst anomalies in the mid latitude band around 40 n effectively excite the positive phase of the nao which in turn reinforces the tripole sst anomalies this relationship was further confirmed by a nine member ensemble agcm experiment forced by the relevant sst anomalies since the forcing and response sst anomaly patterns bear some resemblance these results manifest positive feedback at work in the coupled atmosphere ocean patterns the processes responsible for this positive feedback were elaborated by a series of linear model experiments the local thermal adjustment of the atmosphere to the sst anomalies results in increased precipitation over the gulf stream region associated diabatic heating applied to a linear baroclinic model yields a positive height response to the east which highly influences the southern part of the nao this stationary response in turn induces a northward deflection in the storm track activity leading to an eddy vorticity feedback that tends to force the positive phase of the nao

diabatic heating profiles over the continental convergence zone during the monsoon active spells the present paper aims to bring out the robust common aspects of spatio temporal evolution of diabatic heating during the monsoon intraseasonal active phases over the continental tropical convergence zone ctcz the robustness of spatio temporal features is determined by comparing the two state of the art reanalyses ncep climate forecast system reanalysis and modern era retrospective analysis the inter comparison is based on a study period of 26 years 1984 2009 the study confirms the development of deep heating over the ctcz region during the active phase and is consistent between the two datasets however the detailed temporal evolution of the vertical structure e g vertical tilts of heating differs at times the most important common feature from both the datasets is the significant vertical redistribution of heating with the development of shallow low level heating and circulation over the ctcz region 3 7 days after the peak active phase the shallow circulation is found to be associated with increased vertical shear and relative vorticity over certain regions in the subcontinent this increased vertical shear and relative vorticity in the lower levels could be crucial in the sustenance of rainfall after the peak active phase model experiments with linear dynamics affirm the role of shallow convection in increasing the lower level circulation as observed

sedimentary response to late quaternary sea level changes in the romagna coastal plain northern italy data from 17 continuously cored boreholes 40 170 m deep reveal the subsurface stratigraphy of the romagna coastal plain sedimentological and microfaunal data allow the distinction of eight facies associations of late pleistocene holocene age including 18 lithofacies and 16 faunal associations ten 14c dates provide the basis to establish a sequence stratigraphic framework for the succession corresponding to the upper part 35 ky bp of the last glacio eustatic cycle the eight facies associations can be grouped into lowstand transgressive and highstand systems tracts the upper part of the lowstand systems tract consists of alluvial plain deposits these accumulated during the late pleistocene when the shoreline was 250 km south of its present day position a pronounced stratigraphic hiatus between 25 and 8 8 ky bp is invariably recorded at the upper boundary transgressive surface of these pleistocene indurated and locally pedogenized alluvial deposits the succeeding postglacial history is represented by a well developed transgressive regressive cycle transgressive deposits interpreted to reflect the rapid landward migration of a barrier lagoon system include two wedge shaped paralic and marine units these thicken in opposite directions and are separated by a ravinement surface above the transgressive deposits the maximum flooding surface mfs marks the change from a transgressive barrier lagoon complex to a prograding wave dominated delta system early po delta the mfs can be traced landwards where it constitutes the base of lagoonal deposits an aggradational to progradational stacking pattern of upper delta plain marsh lower delta plain lagoon bay and delta front beach ridge deposits reflects the progressive increase in the sediment supply accommodation ratio during the following highstand the alluvial deposits capping the sequence accumulated by the 13th century ad in response to an avulsion event that caused abandonment of the former po delta lobe and the northward migration of the po river towards its present position

a modified theory of bottom crevasses used as a means for measuring the buttressing effect of ice shelves on inland ice sheets bottom crevasses are fractures that extend upward into floating ice shelves they form when seawater penetrates the base of the ice shelf and ruptures the ice up to the level at which englacial stresses equal the stress of the seawater for a freely floating ice shelf the penetrating level of closely spaced crevasses is estimated at about half the ice thickness h for an isolated crevasse the level is about h 4 however an analysis of the heights and locations of bottom crevasses in the ross ice shelf shows that none of the crevasses approach the predicted limits perhaps because the existing theory does not include the back stress b which is present in bounded ice shelves by reformulating the theory to include a back stress term b can be evaluated experimentally from radar measurements of crevasse height and ice thickness the magnitude of b 2 bars in the grid northwest corner of the ice shelf suggests the ice shelf is playing an important role in buttressing the inland ice sheet

estimate of the subglacier dielectric constant of an ice shelf using a ground penetrating step frequency radar the mass balance of the antarctic ice cap its stability and the role of the surrounding ice shelf in bottomwater mass formation is to a large extent dictated by processes associated with subsurface freezing and melting where the submerged ice meets the surrounding ocean it is demonstrated how multifrequency ground penetrating radar data collected at the riiser larsenisen can be used to examine the physical conditions of the ice shelf subsurface the received radar signal from three different frequency intervals 10 30 155 170 and 330 360 mhz range of wavelengths from 15 to 0 5 m in the ice was analyzed by using a plane reflector model it is demonstrated that the data can be successfully used to distinguish between types of ice at the ice ocean interface such as for freezing marine ice melting marine ice melting meteoric ice from the ice cap and melting firn ice the data analysis shows that the subsurface can be regarded as rough on length scales in the order of 1 m

the role of sediment supply in controlling alluvial architecture an example from the spanish pyrenees this study isolates the controls on the alluvial architecture of two interfingering late lutetian fluvial systems preserved at the northern margin of the tremp graus basin in the south central pyrenees one of these a northerly mountain belt derived high gradient bedload dominated gravelly system displays marked variations in its alluvial architecture with systematic changes in the width depth internal facies arrangement and stacking pattern of its channel bodies the other an easterly basin axis derived lower gradient poorly drained alluvial system displays no discernible systematic variations in alluvial architecture a common control that would similarly affect both of the interfingering fluvial systems cannot be responsible for their contrasting architectural patterns variations in base level despite the contemporaneous shoreline being only 18 km downstream climate or the tectonic rotation of the study area are therefore discounted fluctuations in sediment supply to the northerly derived system resulting from the episodic uplift of its drainage basin are instead proposed although intrinsic controls cannot be totally discounted similar sediment flux variations in the headwaters of the easterly derived system are envisaged but its longer lower gradient transport path was effective in dampening out these fluctuations upstream of the study area

mineralogical signatures of lake baikal sediments sources of sediment supplies through late quaternary abstract the mineralogical composition of late quaternary sediments was investigated in three piston cores recovered on elevated plateaus in lake baikal on continent ridge a northern extension of academician ridge in the north basin on the posolsky bank near the selenga delta and on the vydrino shoulder in the south basin the sediments are alternating biogenic diatom rich muds and terrigenous silty clays with sandy layers occurring in the southern vydrino core core stratigraphy is based on ams 14 c dates on pollen diatom zonation and magnetic record correlation the 6 10 m long cores cover the last 40 kyr in vydrino 60 kyr in posolsky and 185 kyr in continent ridge the bulk clay

climatic versus halokinetic control on sedimentation in a dryland fluvial succession fluvial systems and their preserved stratigraphic expression as the fill of evolving basins are controlled by multiple factors which can vary both spatially and temporally including prevailing climate sediment provenance localized changes in the rates of creation and infill of accommodation in response to subsidence and diversion by surface topographic features in basins that develop in response to halokinesis mobilized salt tends to be displaced by sediment loading to create a series of rapidly subsiding mini basins each separated by growing salt walls the style and pattern of fluvial sedimentation governs the rate at which accommodation becomes filled whereas the rate of growth of basin bounding salt walls governs whether an emergent surface topography will develop that has the potential to divert and modify fluvial drainage pathways and thereby dictate the resultant fluvial stratigraphic architecture discerning the relative roles played by halokinesis and other factors such as climate driven variations in the rate and style of sediment supply is far from straightforward diverse stratigraphic architectures present in temporally equivalent neighbouring salt walled mini basins demonstrate the effectiveness of topographically elevated salt walls as agents that partition and guide fluvial pathways and thereby control the loci of accumulation of fluvial successions in evolving mini basins drainage pathways can be focused into a single mini basin to preserve a sand prone fill style whilst leaving adjoining basins relatively sand starved by contrast over the evolutionary history of a suite of salt walled mini basins region wide changes in fluvial style can be shown to have been driven by changes in palaeoclimate and sediment delivery style the triassic moenkopi formation of the south western usa represents the preserved expression of a dryland fluvial system that accumulated across a broad low relief alluvial plain in a regressive continental to paralic setting within south eastern utah the moenkopi formation accumulated in a series of actively subsiding salt walled mini basins ongoing evolution of which exerted a significant control on the style of drainage and resultant pattern of stratigraphic accumulation drainage pathways developed axial parallel to salt walls resulting in compartmentalized accumulation of strata whereby neighbouring mini basins record significant variations in sedimentary style at the same stratigraphic level despite the complexities created by halokinetic controls the signature of climate driven sediment delivery can be deciphered from the preserved succession by comparison with the stratigraphic expression of part of the system that accumulated beyond the influence of halokinesis and this approach can be used to demonstrate regional variations in climate controlled styles of sediment delivery

dynamical response of the south asian monsoon trough to latent heating from stratiform and convective precipitation simulation experiments using a simplified atmospheric gcm and supplementary diagnostic analyses of observations are performed to understand how the south asian monsoon trough mt responds dynamically to latent heating from mesoscale convective systems mcss observations reveal that the mt during active monsoons is characterized by a deep cyclonic vorticity extending from the surface to 350 hpa and organized mcss covering over 3500 4000 km along the indo gangetic plains the mcss during active monsoons are composed of a relatively higher abundance of stratiform type precipitation mostly nimbostratus as compared to the convective type the results suggest that a stratiform type heating profile is very effective in promotingupward development of continental scale cyclonic circulation well above the midtroposphere over the mt region the vertical development involves a dynamical uplift of the layer of cyclonic circulation and is induced by midlevel 600 500 hpa convergence and vorticity stretching above 500 hpa by varying the population of stratiform and convective rain types in the simulation the horizontal scale of midlevel vorticity response is shown to increase significantly with stratiform population in contrast the midlevel response is more localized when the mcs is dominated by deep convective clouds for large stratiform populations the midlevel responseis found to extend far westward up to the northernflanks of the africanitcz indicativeof rossby wave dispersion of pv anomalies that are generated near the level of maximum heating gradient from the present findings one can conclude that the vertical deepening of mt during active monsoons is not merely a localized phenomenon instead it represents a large scale dynamical response to organized mcss that exert pivotal influence on the upward development of cyclonic circulation well above the midtroposphere

tertiary evolution of the intra carpathian area a model abstract the outer carpathian flysch nappes encircle an intra carpathian domain which can be divided into two megatectonic units north pannonian and tisza mostly on the basis of contrasting mesozoic and palaeogene facies development we see two major kinematic problems to be solved 1 1 the present distribution of the mesozoic and palaeogene facies is mosaic like and some belts form exotic bodies within realms of austroalpine affinity 2 2 late eocene palinspastic reconstruction of the outer carpathian flysch nappes suggest that the entire intra carpathian area must have been located several hundreds of kilometres to the south and to the west of its present position neogene extension can account for shortening in the external carpathian nappes but is unable to explain mesozoic facies anomalies and offsets of palaeogene formations we suggest that evolution of the intra carpathian area involved first late palaeogene early miocene juxtaposition of the north pannonian and tisza megatectonic units accompanied by the closure of the external carpathian flysch troughs thereafter extension of this amalgamated unit occurred which was compensated by thrusting of flysch nappes onto the european foreland and formation of molasse foredeeps eastward escape of the north pannonian unit from the alpine collisional belt involved left lateral shear along the pieniny klippen belt and right lateral shear along the mid hungarian zone parts of the late palaeogene basin and an early miocene volcanic edifice were dissected offset and elongated by several 100 kms the driving mechanism of the eastward escape of the intra carpathian area can be related to the collision of apulia and europe and the subduction of the external carpathian crust under the pannonian units the escape ceased gradually in the early miocene when oblique collision between the north pannonian unit and european continent occurred neogene extension of the pannonian region was an areal deformation the extension at locally variable rate resulted in the break up of the heterogenous floor of the neogene basin the driving mechanism of basin extension and contemporaneous compressional deformation of the external carpathians is thought to be related to ongoing subduction involving the marginal part of the attenuated european continental crust tectonic activity in the carpathians and basin subsidence and volcanism shifted in time and in unison from the west toward the east southeast

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

a study of vertical cloud structure of the indian summer monsoon using cloudsat data precise specification of the vertical distribution of cloud optical properties is important to reduce the uncertainty in quantifying the radiative impacts of clouds the new global observations of vertical profiles of clouds from the cloudsat mission provide opportunities to describe cloud structures and to improve parameterization of clouds in the weather and climate prediction models in this study four years 2007 2010 of observations of vertical structure of clouds from the cloudsat cloud profiling radar have been used to document the mean vertical structure of clouds associated with the indian summer monsoon ism and its intra seasonal variability active and break monsoon spells associated with the intra seasonal variability of ism have been identified by an objective criterion for the present analysis we considered cloudsat derived column integrated cloud liquid and ice water and vertically profiles of cloud liquid and ice water content over the south asian monsoon region deep convective clouds with large vertical extent up to 14 km and large values of cloud water and ice content are observed over the north bay of bengal deep clouds with large ice water content are also observed over north arabian sea and adjoining northwest india along the west coast of india and the south equatorial indian ocean the active monsoon spells are characterized by enhanced deep convection over the bay of bengal west coast of india and northeast arabian sea and suppressed convection over the equatorial indian ocean over the bay of bengal cloud liquid water content and ice water content is enhanced by 90 and 200 respectively during the active spells an interesting feature associated with the active spell is the vertical tilting structure of positive clwc and ciwc anomalies over the arabian sea and the bay of bengal which suggests a pre conditioning process for the northward propagation of the boreal summer intra seasonal variability it is also observed that during the break spells clouds are not completely suppressed over central india instead clouds with smaller vertical extent 3 5 km are observed due to the presence of a heat low type of circulation the present results will be useful for validating the vertical structure of clouds in weather and climate prediction models

ocean access to a cavity beneath totten glacier in east antarctica totten glacier has the largest thinning rate in east antarctica a derivation of the sea floor bathymetry reveals entrances to the ice cavity beneath the glacier that could allow deep warm water to enter and enhance basal melting

linear response of a stratified tropical atmosphere to convective forcing abstract the three dimensional response of the tropical atmosphere to an isolated heat source is investigated using a primitive equation model linearized about a resting basic state on an equatorial plane the model equations are solved by applying vertical and horizontal normal mode transforms the thermal forcing was chosen to simulate the convection which occurs over tropical south america during the southern hemisphere summer the vertical dependence of the forcing is such that the heating is zero at the top and bottom boundaries with a variable level of maximum beating the model results with steady forcing are compared with the average circulation over tropical south america for a 19 day period in the southern hemisphere summer of 1979 and it is shown that the model reproduces many aspects of the observed circulation the partition of the energy of the steady state response between the vertical modes is calculated and it is shown that the internal mode with an equivalent depth of 208 m is domina

structures and mechanisms of the northward propagating boreal summer intraseasonal oscillation abstract the spatial and temporal structures of the northward propagating boreal summer intraseasonal oscillation bsiso are revealed based on the analysis of both the echam4 model simulation and the ncep ncar reanalysis the bsiso structure and evolution characteristics simulated by the model bear many similarities to those derived from the ncep ncar reanalysis the most notable features are the remarkable meridional asymmetries relative to the bsiso convection in the vorticity and specific humidity fields a positive vorticity perturbation with an equivalent barotropic structure appears a few latitude degrees north of the convection center the maximum specific humidity also shows a clear northward shift in the lower troposphere two internal atmospheric dynamics mechanisms are proposed to understand the cause of the northward propagation of the bsiso the first is the vertical shear mechanism the key process associated with this mechanism is the generation of barotropic vorticity due to the couplin

tracing the origin of loess in hungary with the help of heavy mineral composition data abstract heavy mineral composition of the fine sand fraction in the hungarian loess sediments provides important data about the closer sources of the loess in the carpathian basin quantitative detrital heavy mineral compositions of 216 loess loess like sediment and paleosol samples were compared to each other and to recent fluvial sands and different cenozoic sands and sandstones of hungary using statistical methods cluster analysis principal component analysis and discriminant analysis usually garnet is the most frequent detrital heavy mineral in the studied loess sections followed by chlorite magnetite epidote and amphiboles old loess and young loess have similar compositions indicating uniform or similar sources based on the similarities the garnet rich loess sediments could originate from aeolian reworking of the floodplain sediments of the danube and other rivers of transdanubia and the local cenozoic sands of the uplifting transdanubian central range and transdanubian hilly region the biotite and tourmaline rich loess in south transdanubia and the loess with high pyroxene content in the north hungarian range had some material from nearby sources weathered granitoids and volcanic rocks respectively or sediments of local rivers which carried detritus of these rocks the new results presented in this paper confirm numerous earlier ideas about the origin of loess in the carpathian basin but also suggest newly identified sources of the loess particles at several locations

the thermal regime of sub polar glaciers mapped by multi frequency radio echo sounding radio echo soundings provide an effective tool for mapping the thermal regimes of polythermal glaciers on a regional scale radar signals of 320 370 mhz penetrate ice at sub freezing temperatures but are reflected from the top of layers of ice which are at the melting point and contain water radar signals of 5 20 mhz on the other hand see through both the cold and the temperate ice down to the glacier bed radio echo soundings at these frequencies have been used to investigate the thermal regimes of four polythermal glaciers in svalbard kongsvegen uversbreen midre lovenbreen and austre broggerbreen in the ablation area of kongsvegen a cold surface layer 50 160m thick was underlain by a warm basal layer which is advected from the temperate accumulation area the surface ablation of this cold layer may be compensated by freezing at its lower cold temperate interface this requires that the free water content in the ice at the freezing interface is about 1 of the volume the cold surface layer is thicker beneath medial moraines and where cold based hanging glaciers enter the main ice stream on uversbreen the thermal regime was similar to that of kongsvegen a temperate hole was found in the otherwise cold surface layer of the ablation area in a surface depression between kongsvegen and uversbreen where meltwater accumulates during the summer near the subglacial lake setevatnet 250 m a s l lovenbreen was frozen to the bed at the snout and along all the mountain slopes but beneath the central part of the glacier a warm basal layer up to 50m thick was fed by temperate ice from two cirques on austre broggerbreen a temperate basal layer was not detected by radio echo soundings but the basal ice was observed to be at the melting point in two boreholes

the international bathymetric chart of the southern ocean ibcso version 1 0 a new bathymetric compilation covering circum antarctic waters the international bathymetric chart of the southern ocean ibcso version 1 0 is a new digital bathymetric model dbm portraying the seafloor of the circum antarctic waters south of 60 degrees s

anvil clouds of tropical mesoscale convective systems in monsoon regions the anvil clouds of tropical mesoscale convective systems mcss in west africa the maritime continent and the bay of bengal have been examined with trmm and cloudsat satellite data and arm ground based radar observations the anvils spreading out from the precipitating cores of mcss are subdivided into thick medium and thin portions the thick portions of anvils show distinct differences from one climatological regime to another in their upper portions the thick anvils of west africa mcss have a broad flat histogram of reflectivity and a maximum of reflectivity in their lower portions the reflectivity histogram of the bay of bengal thick anvils has a sharply peaked distribution of reflectivity at all altitudes with modal values that increase monotonically downward the reflectivity histogram of the maritime continent thick anvils is intermediate between that of the west africa and bay of bengal anvils consistent with the fact this region comprises a mix of land and ocean influences it is suggested that the difference between the statistics of the continental and oceanic anvils is related to some combination of two factors 1 the west african anvils tend to be closely tied to the convective regions of mcss while the oceanic anvils are more likely to be extending outward from large stratiform precipitation areas of mcss and 2 the west african mcss result from greater buoyancy so that the convective cells are more likely to produce graupel particles and detrain them into anvils copyright 2009 royal meteorological society

role of stratiform rainfall in modifying the northward propagation of monsoon intraseasonal oscillation 1 the stratiform and convective rain rate measurement from the tropical rainfall measuring mission trmm satellite data can give a realistic idea of the latent heating distribution in the tropics the vertical profile of diabatic heating related to the convective and the stratiform rain is known to modulate the dynamical response of atmosphere and also the vertical structure of madden julian oscillation in this study the contribution of the stratiform and convective rain rate to the total rain rate during different phases of the northward propagating boreal summer monsoon intraseasonal oscillation iso is examined using the trmm data two new insights have emerged from this analysis first unlike conventional wisdom the convective component shows weak northward propagation and grows and decays in situ during the evolution of active and break phases while the northward propagation of the monsoon iso is largely achieved by organized movement of the stratiform component second the trademark meridional dipole pattern of total rainfall between the monsoon trough zone and the southern equatorial indian ocean also arises largely from the contribution of stratiform anomalies as the northward propagation of the monsoon iso is known to be due to the anomalous response of the atmosphere to heating in the presence of mean easterly vertical shear modification of the vertical profile of heating due to a contribution from stratiform rain could influence the northward propagation of the monsoon iso this hypothesis is tested using a simple global atmospheric circulation model to study the response of the convective and stratiform heating profiles on the modification of the mean condition modification in the large scale response of the atmosphere as a result of proper specification of convective and stratiform heating anomalies indicates that the presence of stratiform heating favors the northward propagation of the heat source thereby facilitating the positive feedback leading to northward propagation of the monsoon iso these results underline the importance of simulating the partitioning of convective and stratiform rain by cumulus parameterization in climate models if they have to get the space time structure of the summer isos correct

dynamics of breaks in the indian summer monsoon abstract in this paper the authors present results of diagnostic analysis of observations and complementary experiments with a simple numerical model that enable them to synthesize the morphology and dynamics of breaks in the indian summer monsoon ism almost one week ahead of the onset of a break spell over india a monotonically decreasing trend in convective activity is found to occur over the bay of bengal in response to a steady eastward spreading of dry convectively stable anomalies from the equatorial indian ocean a major intensification of the convectively stable anomalies over the bay of bengal is seen about 2 3 days prior to commencement of a monsoon break both observations and modeling experiments reveal that rapid northwest propagating rossby waves are triggered in response to such a large strengthening of the convectively stable anomalies it is shown that an abrupt movement of anomalous rossby waves from the bay of bengal into northwest and central india marks the initiation of a break

tectonically controlled quaternary intracontinental fluvial sequence development in the nyirseg pannonian basin hungary abstract the quaternary fluvial succession of the nyirseg ne hungary a proximal sub basin of 4000 km2 in the intracontinental pannonian basin was studied based on log facies analysis regional mapping of sequences was established by analysis of fully cored boreholes and high scale local correlations in densely drilled areas the age of the sequences was determined by correlating the magnetic susceptibility ms record of the fully cored boreholes with that of the reference hungarian boreholes dated paleomagnetically devavanya 1 and veszt 1 in cooke et al 1979 to give the hungarian data global perspective they were correlated to the ms curve of the chinese loess ding et al 2005 that are in turn correlated with the marine isotope record lisiecki and raymo 2005 gibbard and cohen 2008 the ages of the mapped sequence boundaries are 2 62 2 26 2 12 1 22 1 04 0 58 and 0 34 ma respectively and can be related to the transitions from cool to warm conditions regional unconformities at 2 26 2 12 1 22 and 0 58 ma also coincide with activity maxima of the radiometrically dated quaternary volcanism this high frequency of climatically controlled erosive sequence boundaries in the structurally active periods indicates that the sedimentary record of climatic erosion is better expressed in times when structural changes generate instability in the drainage network the occurrence of packages of regional unconformities in relation to volcanic activity enables the geochronological dating of episodes in the quaternary compression of the carpathian pannonian region the role of tectonic control on the climatically induced changes in the drainage network has been explained by a structural development model based on seismic gravity and magnetic data the changes in the local paleohydrology were triggered by a compression related elevation of the basement and the associated occurrence of a local transtension related subsidence

perspectives on the sequence stratigraphy of continental strata this report is the result of a working group on continental sequence stratigraphy that was set up at the 1991 nuna conference in banff canada to date sequence stratigraphic concepts have been applied mainly to the marine realm but unconformity bounded units have long been recognized in nonmarine strata successful application of sequence stratigraphic concepts to continental strata requires careful consideration of controls on base level and sediment supply as with shallow marine environments relative sea level can be considered as the stratigraphic as well as the geomorphic base level for coastal nonmarine settings farther inland stratigraphic base level which determines accommodation space is more complex and takes various forms such as the graded profile for fluvial strata groundwater tables for some eolian strata and lake level for some intermontane sediments sediment supply is also generally a more complex variable for nonmarine environments than in the marine realm because of the proximity to the source area the influence of climate and tectonism on sediment supply can clearly be seen in many continental sediments the fact that the major controls of climate tectonism and eustasy are somewhat interdependent and that a change in one parameter will most likely be reflected in others is also more readily apparent in continental strata although in its infancy sequence stratigraphic concepts have been applied to a wide variety of continental settings in attempts to explain variations in facies architecture of particular interest are studies that have linked fluvial architecture on coastal plains to variations in relative sea level as indicated by coeval marine strata and studies of lacustrine environments that show marked variation in facies between highstand and lowstand deposits the application of sequence stratigraphy to continental strata will likely result in the development of better correlation techniques and models that better predict the location and nature of fluvial and eolian reservoirs

provenance of fluvial terrace sediments within the waipaoa sedimentary system and their importance to new zealand source to sink studies late pleistocene fluvial terrace deposits within the waipaoa river system of north island new zealand provide some insight into the fluvial history of the region that can be potentially translated to the marine sedimentary record pebble counts and sand detrital modes from terrace remnants suggest significant compositional differences between these terraces and the modern stream deposits the terrace deposits are enriched in sandstone lithics sand and gravel as well as monomineralic quartz and feldspar sand in contrast the modern waipaoa river is dominated by mudstone fragments mainly products of gullying in the waipaoa river headwaters region both the terrace and modern river sand show a compositional dependency on grain size with increasing lithic components in the coarse sand fractions carbonate lithic content and proportions of lithic types in the modern river and terrace sediments can be related to the distribution of calcareous geological units across the region for example the calcareous lithics sand and gravel in the mangatu river a major tributary of the waipaoa are derived from deep water facies allochthon that dominate the catchment these carbonate facies are petrographically distinct from the marl calcareous mudstone that dominates elsewhere in the waipaoa river system such as the pliocene units in the waimata river catchment the combined petrologic data sets from the modern rivers and terraces in the waipaoa river system provide a model to interpret the provenance of sandy deposits in the offshore marine realm

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

notes on southern ocean hydrography sea ice and bottom water formation abstract the southern ocean circulation and sea ice distribution is briefly described the formation of extremely cold bottom water in the weddell sea and its relation to the floating ronne filchner ice shelves is discussed it is shown that a concentrated swift eroding bottom current with anomalous low 18 o ratio transports the cold and dense ice shelf water from the shelf towards large depths comments are made on possible implications of this process for the large scale deep water circulation and for the interpretation of sediment cores

milankovitch scale multi proxy records from fluvial sediments of the last 2 6 ma pannonian basin hungary abstract the continuous cores of two nearly 500 m deep boreholes cutting pleistocene fluvial sequences in the eastern part of the pannonian basin hungary have been studied magnetostratigraphy indicates that the sediment sequences span the last 2 6 ma without significant hiatuses comparison of systematic variations in magnetic susceptibility with changes in grain size distribution revealed milankovitch scale cyclicity in sedimentation of 40 and 100 kyr cyclicity which also shows a correspondence with the 18o variations of the odp 677 site comparison of pollen and gastropod paleoecological data with the magnetic susceptibility proxies suggests that climate was a major allogenic control on the cyclicity zones of high magnetic susceptibility correspond closely with sandy and coarse silty parts of the borehole successions which largely coincide with pollen and molluscs indicating a warm climate on the contrary zones with low magnetic susceptibility correspond to silts and clays and in most cases coincide with cold climate indicator pollen and molluscs heavy mineral and xrd studies revealed that magnetic susceptibility reflects the absolute amount of detrital fe oxide minerals mostly magnetite variations in the amount of magnetite are related to changes in heavy mineral content which arise primarily from changes in sediment supply to the basin by rivers the depositional model for the pleistocene fluvial sediments suggests that sediment flux increased towards the basin during interglacials due to the increased discharge and transport capacity of the rivers while a decreased sediment supply to the distal parts of the basin occurred during glacials a delay between erosion and storage of weathering products near to the source area and subsequent transportation and re deposition of sediments in the basin interior setting is an important cause of this effect

a synthesis of the first garp globa experiment fgge in the equatorial atlantic ocean abstract a synthesis of near surface oceanographic and surface meteorological data collected during the first garp global experiment fgge is presented to portray the oceanic response to the seasonal wind forcing for the period december 1978 to november 1979 inclusive major wind events during fgge are in phase with events given in climatology in particular the february march april relaxation and may enhancement of equatorial winds occurs within one month of the mean event accordingly the oceanic responses such as the may june july appearance of an equatorial cold water tongue the acceleration of the south equatorial current sec and the vertical displacement of the equatorial thermocline occur at the average time furthermore the curl distribution in the vicinity of the north equatorial countercurrent necc during 1979 is similar to the climatological distribution in terms of phase and amplitude except for a westward displacement in the position of the maximum curl as predicted from linear theory the 1979 thermocline response across the necc is in phase with the climatological response with a westward displacement of the maximum thermocline movement deeper than average equatorial thermoclines and a weaker sec may in part be responsible for the anomalously warm sea surface temperatures observed on the equator between 10 w and 30 w from june to november