garnet and tourmaline as provenance indicators of terrigenous material in epicontinental carbonates middle triassic s poland abstract heavy mineral grains contained in epicontinental carbonates are very rarely used for provenance analysis this study deals with detrital heavy minerals separated from marly limestones and marlstones of the gogolin formation gf middle triassic s poland to determine their source rocks and alimentary areas the gf carbonates typically contain 1 wt of heavy minerals within the very fine sand fraction the heavy mineral assemblages consist predominantly of garnets 53 0 92 2 and tourmalines 3 8 30 4 epma analyses reveal four groups of garnets low grs almandines with 30 50 mol prp almandines with 20 35 mol prp and up to 35 mol grs almandines with up to 20 mol sps and rare pyrope grains 60 mol prp the composition of the garnets indicates that hp felsic granulites were their main source rocks but more mafic hp rocks eclogites retrograded eclogites and mafic granulites gneisses mica schists and garnet peridotites also contributed the detrital tourmalines are represented mainly by dravite and less frequently by schorl which were derived mostly from paragneisses and mica schists and in minor part from granitoids and pegmatites the e ne part of the bohemian massif is the most probable location of the source rocks the presumed source rocks presently outcrop in the moldanubian zone the kutna hora unit the svratka unit and the gory sowie massif nowadays the bodies formed by the hp rocks within these units are insufficiently large to act as sources for delivering detrital material in the determined proportions the high content of hp metamorphic grains thus indicates the past existence of extensively exposed and abundant high pressure metamorphic rocks eroded during and or after the middle triassic

shallow marine carbonate sedimentation in a tectonically mobile basin the muschelkalk middle triassic of upper silesia southern poland abstract earthquakes and resulting tsunamis are important geological phenomena however their sedimentary paleorecord is difficult to identify because some fabrics can be generated by other processes and the criteria for discrimination of seismic and non seismic triggers are not fully established this paper presents several deformation and sedimentary structures in the middle triassic carbonates of upper silesia and discusses their seismogenic and tsunami origin and controls on the deformation type intensity preservation potential and geographic distribution the deformation type and intensity were controlled by the primary lithology whereas the lateral continuity of deformed horizons depended on the lateral extent of hosted facies the thickness and abundance of these structures increase towards the krakow lubliniec fault zone which bounded the area from the east and is considered as the main epicentrum of earthquakes and tsunami initiation the discussed fabrics have a universal significance and can potentially be found in other shallow marine carbonate successions

magnetobiostratigraphy of the spathian to anisian lower to middle triassic kcira section albania summary magnetobiostratigraphic data are presented from three early middle triassic hanbulog limestone successions from kqira northern albania a total of 206 standard palaeomagnetic samples were obtained for thermal demagnetization and statistical analysis from the 42 10 and 5m thick sections the reversal bearing characteristic component carried by haematite and magnetite defines a composite sequence of six main polarity intervals kqln to kq3r in which are embedded four short polarity intervals one at the base of kqln and three towards the top of kqlr the early acquisition of the characteristic remanence is supported by the lateral correlation of magnetozones between sections the early middle triassic boundary approximated by the first occurrence of the conodont chiosella timorensis falls close to the kqlr kq2n polarity transition this is in good agreement with recently published magnetobiostratigraphic data from the coeval chios greece sections the palaeomagnetic pole calculated from the kqira characteristic directions lies close to the triassic portion of the apparent polar wander path for laurussia in european coordinates however a 40 45 clockwise rotation of the external zone of the albano hellenic belt to the south of the scutari pec line is thought to have occurred since the early middle miocene the kqira pole acquires a west gondwana affinity when restored for the neogene clockwise rotation if the clockwise rotation was entirely related to neogene tectonics the kqira area was evidently associated with west gondwana and located at 12 16 n of the western tethys margin

peridotite derived detrital pyropes versus high pressure felsic granulite derived pyrope almandine garnets from the lower triassic deposits of the ne foreland of the bohemian massif s poland central europe

timing of recovery from the end permian extinction geochronologic and biostratigraphic constraints from south china four volcanic ash beds bracket the early middle triassic boundary as defined by conodont biostratigraphy in a stratigraphic section in south china high precision u pb dates of single zircons allow us to place the early to middle triassic olenekian anisian boundary at 247 2 ma magnetic reversal stratigraphy allows global correlation the new dates constrain the early triassic interval characterized by delayed biotic recovery and carbon cycle instability to 5 m y this time constraint must be considered in any model for the end permian extinction and subsequent recovery

intense sub kilometer scale boundary layer rolls observed in hurricane fran high resolution observations obtained with the doppler on wheels dow mobile weather radar near the point of landfall of hurricane fran 1996 revealed the existence of intense sub kilometer scale boundary layer rolls that strongly modulated the near surface wind speed it is proposed that these structures are one cause of geographically varying surface damage patterns that have been observed after some landfalling hurricanes and that they cause much of the observed gustiness bringing high velocity air from aloft to the lowest observable levels high resolution dow radar observations are contrasted with lower resolution observations obtained with an operational weather radar which underestimated peak low level wind speeds

authigenic potassium feldspar a tracer for the timing of palaeofluid flow in carbonate rocks northern calcareous alps austria

permian to early triassic magnetostratigraphy from the central european basin in poland implications on regional and worldwide correlations abstract permian early triassic rocks sampled in 15 outcrops 93 hand samples and 11 unoriented boreholes 630 hand samples from the polish part of the central european basin were studied paleomagnetically in spite of extensive remagnetization affecting 50 of samples from the boreholes a magnetic polarity sequence was compiled the polarity pattern is not only common for many sections from the investigated area but also convergent with the global synthetic magnetostratigraphic scale the lower rotliegend early permian rocks contain a reversed polarity record while the upper rotliegend late permian early triassic sediments are characterized by mixed polarity magnetization within the buntsandstein part of that mixed megazone 14 magnetic zones were found buntsandstein sedimentation started with a normal polarity zone which may be compared with that of early griesbachian defined in several places in the world the polarity record noted in the middle buntsandstein sediments could indicate significant stratigraphic gaps or condensations near the middle buntsandstein and rot boundary the comparison of the upper buntsandstein polarity with the early middle triassic magnetostratigraphic data from other basins suggests that the majority or even all the rot sediments should be included in the anisian

a comparison of shear and buoyancy driven planetary boundary layer flows abstract planetary boundary layer pbl flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces these differences are not unexpected in that shear instabilities occur locally while buoyancy force sets up vigorous thermals which result in nonlocal transport of heat and momentum at the same time these two forces can act together to modify the flow field in this study four large eddy simulations less spanning the shear and buoyancy flow regimes were generated two correspond to the extreme cases of shear and buoyancy driven pbls while the other two represent intermediate pbls where both forces are important the extreme cases are used to highlight and quantify the basic differences between shear and convective pbls in 1 flow structures 2 overall statistics and 3 turbulent kinetic energy tke budget distributions results from the two intermediate les cases are used to develop and verify a velocity scaling and a tke budget mode

palaeomagnetism and the age of the cracow volcanic rocks s poland summary permian rhyodacites melaphyres and tuffs from the cracow area south poland were sampled for the palaeomagnetic and isotope studies single grain u pb dating of most zircon grains separated from the rhyodacites gave mean age of magma emplacement of 294 2 2 1 ma some zircons however displayed younger ages 268 7 3 4 ma probably related to the metasomatic alterations of these rocks two permian components of magnetizations related to these processes were isolated and together with previously defined late carboniferous permian palaeomagnetic poles from south poland were used for construction of the regional apparent polar wander path apwp the early permian segment of this apwp shows a certain departure from the coeval part of the fennoscandian apwp due to anticlockwise rotations of studied rocks most probably caused by mid permian sinistral tectonic movements along reactivated prominent variscan faults of central europe this sense of tectonic mobility does not support the hypothesis about transformation from pangea b to pangea a along an intra pangea dextral megashear during the permian older than previously assumed ages of the post variscan igneous rocks of central europe reduce overlap of gondwana s and laurussia s parts of the early permian pangea a

microphysical structure of the marine boundary layer under strong wind and sea spray formation as seen from a 2d explicit microphysical model part iii parameterization of height dependent droplet size distribution abstractthis paper completes a series of studies using a 2d hybrid lagrangian eulerian model to investigate the effect of sea spray on the thermodynamics and microphysics of the hurricane mixed layer the evolution of the mixed layer was simulated by mimicking the motion of an air volume in a lagrangian sense toward a tropical cyclone eyewall along a background airflow during the radial motion sea surface temperature pressure background wind speed sea spray production rate and turbulence intensity were altered according to the available observations analysis of the interaction between the hurricane mixed layer and the upper layers in terms of entrainment heat and moisture fluxes gives a new insight into the role of sea spray in the thermodynamics and microphysics of the mixed layer the evaporation of sea spray leads to an increase in the relative humidity by 10 15 and to a decrease in temperature by about 1 1 5 k as compared to cases where sea spray is excluded sea spray leads to formation o

origin of cone in cone calcite veins during calcitization of dolomites and their subsequent diagenesis a case study from the gogolin formation middle triassic sw poland abstract although bedding parallel cone in cone structure calcite veins are present in the middle triassic gogolin formation in opole silesia their occurrence is limited to the emilowka cellular limestone member marly limestones dedolomites consisting of calcite pseudospar are the host rocks the veins which are up to 3 mm high and 30 cm long are built of densely packed cone columns with individual cones up to 0 7 mm high and 0 6 mm wide at their bases and with vertex angle values ranging from 30 to 50 the cones are microfractured and the adjacent cones are vertically shifted in oblique planes the exceptionally small veins consist of calcite fibres up to 0 15 mm high the veins are built of low magnesium and non ferroan calcite characterized by low 18o values ranging from 6 8 to 7 4 and low 13c values ranging from 2 9 to 4 5 vs pdb these isotopic values are similar to those obtained from the host rocks 18o from 6 8 to 7 4 and 13c from 3 2 to 3 6 vs pdb and they are strongly depleted in comparison with the isotopic values of other carbonate particles from the gogolin formation the veins only formed in one lithostratigraphic member suggesting that their origin is related to processes which acted only locally there are two unique processes that the emilowka cellular limestone member alone in the gogolin formation underwent early diagenetic evaporitic dolomitization of lime mud in the sabkha environment and subsequent calcitization of dolomite dolomitization led to sediment cohesion loss porosity increase and initial horizontal laminae separation as a result of the transformation of calcium carbonate to dolomite within anisotropic deposits similar values of geochemical parameters obtained from the vein calcite and the host rock calcite are evidence that vein filling precipitation was contemporary with dedolomitization geochemical data combined with sedimentological research and burial history show meteoric derived waters saturated with respect to calcite as a source of the vein calcite dedolomitization and vein precipitation may have taken place from the norian early jurassic to the late jurassic when the study area became eroded land and the emilowka cellular limestone member may have acted as a local paleoaquifer conducting the meteoric derived waters solid inclusions in the veins detached from the host rock and the calcitized nodules show that the force of calcite crystallization was the main factor responsible for vein widening vertical shifts of adjacent cones remnants of primary fibrous calcite crystals as well as the burial history justify the application of tarr s theory in interpreting the origin of the secondary cone in cone structure within the fibrous structure veins the timing and the particular conditions required for the cones to develop are uncertain

an assessment of marine atmospheric boundary layer roll detection using sentinel 1 sar data abstract the ability of high resolution synthetic aperture radar sar to detect marine atmospheric boundary layer mabl roll induced roughness modulation of the sea surface wave field is well known this study presents sar measurements of mabl rolls using global coverage data collected by the european space agency s c band sentinel 1a satellite in 2016 2017 an automated classifier is used to identify likely roll events from more than 1 3 million images that were acquired at two incidence angles of 23 and 36 5 in either vv or hh polarization characteristics of the detected rolls are examined for different wind speeds polarizations incidence and relative azimuth angles roll detection counts are much higher at the higher incidence angle and nearly equivalent for vv and hh polarizations detection depends strongly on the relative azimuth with roll detection rates at crosswind being 3 10 times lower than for up or downwind all data show a low wind speed threshold near 2 m s 1 and that rolls are most commonly observed at wind speeds near 9 m s 1 for all viewing configurations we find that rolls induce a wide range of mean surface wind speed modulation with the most frequent value being 8 3 5 roll detection at crosswind is associated with stronger roll induced surface wind enhancement dependencies of roll detection on the incidence and relative azimuth angles are consistent with rapid short scale wind wave adjustments to the roll induced surface wind gusts these cm scale waves are highly directional and provide limited crosswind backscatter at shallower incidence angles the same roll induced surface forcing is thus not equally detectable at all viewing geometries or polarizaions stronger and possibly longer duration wind forcing is likely needed to produce detectable roll induced modulations at crosswind

coherent turbulence in the boundary layer of hurricane rita 2005 during an eyewall replacement cycle abstractthe structure of coherent turbulence in an eyewall replacement cycle in hurricane rita 2005 is presented from novel airborne doppler radar observations using the imaging wind and rain air

a second order bulk boundary layer model abstract bulk mass flux models represent the large eddies that are primarily responsible for the turbulent fluxes in the planetary boundary layer as convective circulations with an associated convective mass flux in order for such models to be useful it is necessary to determine the fractional area covered by rising motion in the convective circulations this fraction can be used as an estimate of the cloud amount under certain conditions matching conditions have been developed that relate the convective mass flux to the ventilation and entrainment mass fluxes these are based on conservation equations for the scalar means and variances in the entrainment and ventilation layers methods are presented to determine both the fractional area covered by rising motion and the convective mass flux the requirement of variance balance is used to relax the well mixed assumption the vertical structures of the mean state and the turbulent fluxes are determined analytically several aspects of this simple m

estimation and mapping of hurricane turbulent energy using airborne doppler measurements abstract hurricane turbulent kinetic energy tke was computed using airborne doppler measurements from the noaa wp 3d tail radars and tke data were retrieved for a variety of storms at different stages of their life cycle the geometry of the radar analysis coupled with the relatively small beam resolution at ranges 8 km allowed for the estimation of subkilometer turbulent processes two dimensional profiles of tke were constructed and revealed that the strongest turbulence was generally located in convective regions such as the eyewall with magnitudes often exceeding 15 m2 s 2 and in the boundary layer with values of 5 10 m2 s 2 in the lowest kilometer a correlation analysis showed that the strong turbulence was generally associated with strong horizontal shear of vertical and radial wind components in the eyewall and strong vertical shear of horizontal wind in the boundary layer mean vertical profiles of tke decrease sharply above the hurricane boundary layer and level off at low magnitude for al

prevalence of tornado scale vortices in the tropical cyclone eyewall analyses of datasets from manned research flights that penetrated hurricane eyes and tropical cyclone tc damage surveys strongly suggest the existence of tornado scale vortices in the turbulent boundary layer of the tc eyewall however their small horizontal scale their fast movement and the associated severe turbulence make the tornado scale vortex very difficult to observe directly to understand tornado scale vortices in the tc eyewall and their influence on the tc vortex mesoscale rainbands and convective clouds a numerical experiment including seven nested domains with the smallest horizontal grid interval of 37 m is conducted to perform a large eddy simulation les with the advanced weather research and forecast wrf model we show that most of the observed features associated with tornado scale vortices can be realistically simulated in the wrf les framework the numerical simulation confirms the existence of simulated tornado scale vortices in the turbulent boundary layer of the tc eyewall our numerical experiment suggests that tornado scale vortices are prevalent at the inner edge of the intense eyewall convection

small scale spiral bands observed in hurricanes andrew hugo and erin abstract analysis of radar data taken from the three intense hurricanes that passed close to wsr 57 and wsr 88d radar sites at their point of landfall illustrate small scale spiral bands that are frequently observed within 100 km or so of the hurricane center faintly visible in the radar reflectivity images these bands have scales of 10 km across the band and can extend for 100 km as they spiral outward in a clockwise fashion they appear to move around the hurricane with speeds close to the tangential wind at the level of the bands and are characterized by enhanced updrafts with higher equivalent potential temperature in the regions of elevated reflectivity they induce wind speed variations of at least 8 m s 1 across the bands the authors suggest that these small scale hurricane spiral bands are similar to boundary layer rolls although they extend through depths of 5 6 km which is more than would be expected for rolls in the boundary layer near the sea the data presented here are not sufficient to

multiple scale simulations of stratocumulus clouds 1 this study introduces a flexible multiple nested modeling framework developed from the weather research and forecasting wrf model for boundary layer cloud research it features a nested large eddy simulation in a hindcasting mode that allows a direct comparison between simulations and observations using this approach we simulated two stratocumulus cases observed at the southern great plains observing site the simulation observation comparisons demonstrate that the multiple nested wrf well reproduces the cloud properties and vertical velocity fields detected by cloud radar and other remote sensing instruments the simulations show that 1 the cloud fields can be strongly modulated by mesoscale organizations 2 the vertical velocity variance and skewness in the boundary layer have well defined diurnal variations and are strongly dependent on external forcings but the in cloud turbulent statistics appears to be more controlled by the internal turbulent processes 3 the organized structures of stratocumulus are only slightly skewed which is consistent with the cloud radar observations that the updraft fraction is close to 50 and 4 the vertical distribution of cloud water and the associated high order moments of continental stratocumulus can be substantially different from its marine counterpart due to different ambient thermodynamic structures this study suggests that the multiple scale wrf modeling system provides a great numerical framework that can be used to address various issues regarding the parameterization of boundary layer clouds

wavelet analyses of turbulence in the hurricane surface layer during landfalls using wavelet transform wt this study analyzes the surface wind data collected by the portable wind towers during the landfalls of six hurricanes and one tropical storm in the 2002 04 seasons the wt which decomposes a time series onto the scale time domain provides a means to investigate the role of turbulent eddies in the vertical transport in the unsteady inhomogeneous hurricane surface layer the normalized wt power spectra nwps show that the hurricane boundary layer roll vortices tend to suppress the eddy circulations immediately adjacent to rolls but they do not appear to have a substantial effect on eddies smaller than 100 m for low wind conditions with surface wind speeds less than 10 m s 21 the contributions of small eddies 236 m to the surface wind stress and turbulent kinetic energy tke decrease with the increase of wind speed the opposite variation trend is found for eddies greater than 236 m however for wind speeds greater than 10 m s 21 contributions of both small and large eddies tend to level off as wind speeds keep increasing it is also found that the scale of the peak nwps of the surface wind stress is nearly constant with ameanvalueofapproximately86m whereasthescaleofthepeaknwpsoftkegenerallyincreaseswiththe increase of wind speed suggesting the different roles of eddies in generating fluxes and tke this study illustrates the unique characteristics of the surface layer turbulent structures during hurricane landfalls it is hoped that the findings of this study could enlighten the development and improvement of turbulent mixing schemes so that the vertical transport processes in the hurricane surface layer can be appropriately parameterized in forecasting models

geochemical constraints on the origin of secondary magnetizations in the cambro ordovician royer dolomite arbuckle mountains southern oklahoma abstract geochemical and paleomagnetic results from cambro ordovician royer dolomite in the arbuckle mountains southern oklahoma suggest a connection between dolomite type and magnetizations one dolomite type which is most common in the vicinity of the arbuckle anticline has a dull luminescence low 18 o values coeval to slightly lower 87 sr 86 sr ratios and contains an easterly cambro ordovician magnetization in magnetite to the southeast closer to the ouachita mountain front most of the royer dolomite contains a southeasterly and shallow magnetization in magnetite that is interpreted to be late paleozoic in age in contrast to the other dolomites these dolomites contain abundant authigenic k feldspar and pyrite radiogenic 87 sr 86 sr ratios and have a bright red luminescence all of which are consistent with alteration by basinal fluids at one site a stromatolitic bioherm dolomites similar to those at the arbuckle anticline are surrounded by the altered dolomites the distribution of specimen directions at this site is streaked between a cambro ordovician and late paleozoic direction the results of this study suggest a connection either direct by causing precipitation or indirect by increasing permeabilities for another fluid between a radiogenic fluid and a chemical magnetization in magnetite the relatively unaltered dolomites at the stromatolitic bioherm site escaped the almost pervasive alteration and remagnetization caused by the basinal fluids close to the ouachita mountains a potential source for the fluids

middle triassic magnetostratigraphy and biostratigraphy from the dolomites and greece abstract magnetostratigrapic and biostratigraphic data across the anisian ladinian middle triassic boundary were obtained from the frotschbach seceda section from the dolomites region of northern italy and the vlichos section from the greek island of hydra where the aghia triada published section was also resampled the frotschbach seceda section includes two radiometrically dated u pb tuff levels and covers two of the three chief candidates for the position of the base of the ladinian namely at the base of the secedensis zone or the subsequent curionii zone the aghia triada section yields biochronological evidence for the base of the secedensis zone whose significance is however critically discussed in the light of the magnetostratigraphic correlation with frotschbach seceda the vlichos section can be correlated with aghia triada and frotschbach seceda by means of magnetic polarity stratigraphy and sparse fossil occurrences the satisfactory correlation of the magnetozones allows us to construct a composite geomagnetic polarity sequence tied to tethyan ammonoid and conodont biostratigraphy for about a 2 4 myr interval across the anisian ladinian boundary

intermittent existence of a southern californian upwelling cell during submillennial climate change of the last 60 kyr 1 application of a high resolution multiproxy approach to a sedimentary section drilled at ocean drilling program site 1017 located under a highly active upwelling cell off point conception california provides clear evidence for surface ocean productivity shifts on submillennial timescales during the last 60 kyr the proxies include bulk sediment major and minor elements organic carbon and carbonate concentrations 15n and planktonic foraminiferal species assemblage and carbon isotope determinations the collective results demonstrate that marine productivity in this area was not simply linearly related to cold and warm cycles except during the millennial scale climate oscillations of marine isotope stage mis 3 during that interval the upwelling cell and resulting high productivity were active during warm interstadial events and were largely inactive during cool stadial events however the last glacial maximum was also relatively productive productivity increased dramatically during the bolling warm interval while the allerod and younger dryas were much less productive high coccolithophorid abundance commenced during the earliest holocene after 10 ka the complexity of the productivity response was probably related to interplay between local winds as well as california undercurrent strength

the apparent polar wander path of the european plate in upper triassic lower jurassic times and the liassic intraplate fracturing of pangaea new palaeomagnetic constraints from nw france and sw germany summary in order to constrain the european plate motions during triassic lower jurassic times new palaeomagnetic data were acquired from various triassic liassic sediments of northeastern france and southwestern germany a carnian palaeopole 49 n 131 e k 193 a95 7 n 4 was obtained for keuper marls with consistent directions of normal and reversed polarities rhaetian sandstones also with both polarities and carnian dolomites with a magnetization of probable secondary origin provide a mean pole 51 n 112 e k 109 a95 6 n 6 more westerly than that given above the lower hettangian sampled in limestones of the xeuilley quarry near nancy shows a n r n polarity sequence with well defined anti parallel directions the mean hettangian pole is 55 n 100 e k 123 a95 11 n 3 induan sandstones from the northern vosges show two distinct overprints one consistent with the ladinian carnian magnetizations already observed in the same region the second consistent with the recalculated mean lower jurassic pole of europe five other sites with different rock types also exhibit late overprints with lower jurassic directions the mean pole calculated from these overprints is 74 n 124 e k 125 a95 6 n 6 the revised apparent polar wander path apwp presented here shows that for the mid permian to the earliest jurassic the palaeopoles of europe stayed around 50 latitude while the longitudes drifted from 185 e to 100 e the previously established upper triassic lower jurassic loop of the apwp is shifted westwards by about 25 the revised apwp involves the following plate motions after the late alleghanian tectonic phase which marked the end of the variscan orogeny central western europe rotated counterclockwise during about 70 myr up to the earliest jurassic the south north drift in latitude by 35 nearly 4000 km remained regular from 320 to 205 ma with a constant rate of 3 4cm yr 1 around 205 ma this motion ceased probably because of a collision somewhere in the north of eurasia then in the lower liassic the plate underwent a rapid counterclockwise rotation with a eulerian pole located in northeastern asia synchronous with fracturing in the atlantic and the neotethys areas it is proposed that the intraplate fracturing of pangaea was initiated by the rapid change of the megacontinent motion at the end of the trias

paleomagnetic constraints on the permian triassic boundary in terrestrial strata of the karoo supergroup south africa implications for causes of the end permian extinction event the closure of the palaeozoic witnessed the greatest biotic crisis in earth history surprisingly little is known about the effects and timing of the terrestrial counterpart of the well described end permian mass extinction from known marine successions worldwide in the present study reliable paleomagnetic results were obtained from a pt boundary section in the terrestrial karoo basin of south africa permo triassic aged mudstones from a locality in the eastern cape province yielded two magnetic chrons reverse followed by normal with the boundary possibly close to the reversal this extends to results from a previous study thereby jointly identifying a r n r polarity pattern for this boundary interval the ptb interval is constrained below the red mudstones of the beaufort group at the present locality and within reverse magnetised green mudstone implying a diachronic relation between the marine and terrestrial end permian mass extinction events

magnetostratigraphy of the sherwood sandstone group lower and middle triassic south devon uk detailed correlation of the marine and non marine anisian the sherwood sandstone group in south devon consists of the budleigh salterton pebble beds and the otter sandstone formation the otter sandstone formation comprises four lithostratigraphic sub units from the base labelled a d and contains tetrapods corresponding to the perovkan land vertebrate faunachron and is consequently a key european non marine anisian succession a total of 181 palaeomagnetic specimens from 92 horizons were measured to determine the palaeomagnetic signal the magnetic properties and characteristic remanence is predominantly carried by haematite most of which probably formed early in the depositional and diagenetic history the lower part of the sherwood sandstone group budleigh salterton pebble beds and otter sandstone formation unit a lower part of unit b has predominantly normal polarity magnetozones bs1 bs2 and bs3n with three thin reversed polarity magnetozones the lower part of unit b to the lower part of unit c of the otter sandstone formation is predominantly reverse polarity magnetozones bs3r bs4 and bs5 but includes three short normal polarity intervals the upper ca 50 m of unit c shows a mix of normal and reverse polarity bs6 bs7 with normal dominating the ca 15 m thick unit d is entirely of normal polarity bs8n the magnetostratigraphy allows unambiguous comparison with conodont and ammonite calibrated magnetostratigraphies from elsewhere in europe these show that the bs2 and bs3n magnetozones of the otter sandstone formation are lower aegean to middle pelsonian lower to middle anisian the bs3r to bs5r magnetozone interval is middle pelsonian to lower illyrian middle to upper anisian and the bs6 to bs8n magnetozone interval is middle illyrian to lower fassanian the top of unit d is correlated to an interval in the middle of the nevadites zone close to the anisian ladinian boundary consequently the otter sandstone formation correlates with the muschelkalk in the polish basin but is equivalent to only part of the germanic basin muschelkalk the continuous magnetostratigraphy from the sherwood sandstone group provides additional details of the polarity pattern through the pelsonian to illyrian interval which appears to be lacking in discontinuous marine sections a synthesis of adjacent european sedimentary basins in combination with the magnetostratigraphy suggests that the budleigh salterton pebble beds are probably late spathian to lower aegean

parameterization of continental boundary layer clouds 1 large eddy simulations less of continental boundary layer clouds blcs observed at the southern great plains sgp are used to study issues associated with the parameterization of sub grid blcs in large scale models it is found that liquid water potential temperature l and total specific humidity qt which are often used as parameterization predictors in statistical cloud schemes do not share the same probability distribution in the cloud layer with l skewed to the left negatively skewed and qt skewed to the right positively skewed the skewness and kurtosis change substantially in time and space when the development of continental blcs undergoes a distinct diurnal variation the wide range of skewness and kurtosis of l and qt can hardly be described by a single probability distribution function to extend the application of the statistical cloud parameterization approach this paper proposes an innovative cloud parameterization scheme that uses the boundary layer height and the lifting condensation level as the primary parameterization predictors the les results indicate that the probability distribution of these two quantities is relatively stable compared with that of l and qt during the diurnal variation and nearly follows a gaussian function verifications using les output and the observations collected at the atmospheric radiation measurement arm climate research facility arcf sgp site indicate that the proposed scheme works well to represent continental blcs

latest permian to middle triassic cyclo magnetostratigraphy from the central european basin germany implications for the geomagnetic polarity timescale in central germany the about 1 km thick mainly clastic germanic lower triassic buntsandstein consists of about 60 sedimentary cycles which are considered to reflect variability in precipitation within the epicontinental central european basin most probably due to solar induced short eccentricity cycles they provide a high resolution cyclostratigraphic framework that constitutes the base for creating a composite geomagnetic polarity record in which this paper presents a middle buntsandstein to lowermost muschelkalk magnetostratigraphy obtained from 6 outcrops and 2 wells where a total of 471 samples was collected combined with recently established records a well documented magnetostratigraphy for the upper zechstein to lowermost muschelkalk latest permian to middle triassic of central germany has been constructed encompassing an overall stratigraphic thickness of about 1 3 km and 22 magnetozones derived from about 2050 paleomagnetic samples along with available biostratigraphy this multi disciplinary study facilitates detailed links to the marine realm in order to directly refer biostratigraphically calibrated triassic stage boundaries as well as radioisotopic ages to the buntsandstein cyclostratigraphy and conversely to contribute to calibrating the geologic timescale 2007 elsevier b v all rights reserved

platy corals from the middle triassic of upper silesia poland implications for photosymbiosis in the first scleractinians abstract coral patch reefs from middle triassic upper pelsonian lower illyrian strata in the upper silesia region of southern poland germanic domain of the peri tethys are rare examples of the first scleractinian buildups the shallowing upward succession in the tarnow opolski quarry records a transition from sponge to coral patch reefs interbedded with bioclastic limestones coral pillarstones built by thin branching volzeia szulci are succeeded by platy pamiroseris silesiaca constructing two platestone layers each up to 50 cm thick serial sections through platestones revealed flat to undulose growth form of p silesiaca the maximum observable dimension of the coral plates is 24 cm wide typically up to 12 cm while thickness of most plates is 1 1 5 cm coral plates are interlayered with crinoidal wacke to packstone and microbialites which are locally important component of the platestone platy corals grew in a shallow turbid water environment with changing but dominantly moderate hydrodynamics net sedimentation was low as indicated by the epibionts encrusted to the undersides of the coral plates and locally common microbial fabrics growth interruptions of p silesiaca record events of storm induced sediment input and resuspension of carbonate mud based on the euphotic floor model the flattened morphology of p silesiaca is interpreted as an optimal growth form in a turbid low light environment platy scleractinian assemblages from silesia are the oldest occurrences of this ecological coral group mostly representing deeper mesophotic habitats and support the hypothesis that some of the earliest scleractinians had photosymbionts like modern zooxanthellae

why rolls are prevalent in the hurricane boundary layer recent remote sensing observations show that the hurricane boundary layer flow although energetic is not a region of homogeneous turbulence in fact the observations convincingly demonstrate that a large fraction of the turbulent flow in the regions away from the deep convective rainbands is highly organized into intense horizontal roll vortices that are approximately aligned with the mean wind and span the depth of the boundary layer these observations show that rolls strongly increase the flux of momentum between the underlying surface and the main body of the storm compared to an equivalent hurricane boundary layer flow without rolls the linear and nonlinear dynamics of hurricane boundary layer roll formation are outlined and it is shown why rolls are in fact the expected basic hurricane boundary layer state the model presented here explains the hurricane roll features currently documented in field programs and makes predictions that can be tested in future experiments the primary effects of rolls on the boundary layer fluxes are inherently nonlocal and nongradient and hence cannot be captured by standard downgradient turbulence parameterizations used in hurricane simulations however the nonlinear theory is the proper starting point for developing boundary layer parameterizations that include roll modification of the turbulent fluxes

evaluation of planetary boundary layer parameterizations in tropical cyclones by comparison of in situ observations and high resolution simulations of hurricane isabel 2003 part i initialization maximum winds and the outer core boundary layer in this study thefirst of two parts the planetary boundarylayer pbl depicted in high resolution weather research and forecast model wrf simulations of hurricane isabel 2003 is studied and evaluated by direct comparisons with in situ data obtained during the coupled boundary layer and air sea transfer experiment cblast in particular two boundary layer schemes are evaluated the yonsei university ysu parameterization and the mellor yamada janjic myj parameterization investigation of these schemes is useful since they are available for use with wrf are both widely used and are based on entirely different methods for simulating the pbl in this first part the model domains and initialization are described for additional realism of the low level thermodynamic environment a simple mixed layer ocean model is used to simulate ocean cooling the ysu and myj schemes are discussed along with some modifications standard measures of the accuracy of the hurricane simulations such as track maximum surface wind speed and minimum surface pressure are describedforavarietyofparameterchoicesandforthetwoparameterizations theeffectsontrackandintensity of increased horizontal and vertical resolutions are also shown a modification of the original ysu and myj schemes to have ocean roughness lengths more in agreement with recent studies considerably improves the results of both schemes instantaneous wind maximaon the innermost grid with 1 33 kmresolutionare shown to be an accurate representation of the simulated 1 min sustained winds thesimulatedboundarylayersareevaluatedby directcomparison ofthepblassimulatedandasobserved by in situ data from the cblast experiment in the outer core region of the storm the two pbl schemes and their modifiedcounterparts reproduce the observed pbl remarkably well comparisonsare also made to the observed vertical fluxes of momentum heat and moisture in part ii the detailed comparisons of the intensities and structures of the simulated and observed innercore boundary layers are presented and the reasons for the differences are discussed

la icp ms analysis of rare earth elements in marine reptile bones from the middle triassic bonebed upper silesia s poland impact of long lasting diagenesis and factors controlling the uptake abstract the rare earth elements ree contained in fossil bones are widely used for provenance and palaeoenvironmental studies earlier works suggested that the ree uptake is limited to early diagenesis but more recent research provided evidence of long term open system diffusion in fossil bones we analysed thin walled reptile bones all collected from the same middle triassic 245 ma marine bonebed comprising vertebrate remains of likely different ages to check the influence of the long term diagenesis on the concentrations of ree in terms of impact of pore water the upper parts of the bones are contained in a low permeability crinoidal limestone whereas their lower parts have been affected by diagenetic fluids for a long time we measured ree and other trace element contents in 29 bones using la icp ms totally 660 spots in 45 depth profiles neither the absolute concentrations of the ree and the ree intra bone paas normalised patterns nor the inter element ratios and the la ce and eu anomalies appear useful to distinguish between the likely older and younger bones in the bonebed the mree n enrichment combined with the flat intra bone distributions of the ree lead to conclusion that ree fractionation and substitution for ca were the most important processes responsible for the selective uptake the low permeability host rock and diagenetic fluids had a significant impact on the trace element uptake and their intra bone distribution patterns the lower parts of the bones that likely had a long lasting contact with the diagenetic fluids reveal a relative enrichment in the ree and their easier diffusion into the bone centres the ability of fossil bones to incorporate trace elements over a long time span strongly limits the usage of particularly the older samples for provenance and palaeoenvironmental reconstructions additionally the presented new analyses fill the gap between the available databases of trace element concentrations in fossil bones with regard to middle triassic samples

the permian triassic boundary in the central european basin magnetostratigraphic constraints some stratigraphic interpretations concerning correlation of the permian triasssic transition beds from the central european boreal and tethyan basins are inconsistent with the existing magnetostratigraphic data in addition the suggestion that the permian triassic boundary is located in the lower part of the calvorde formation of the central european basin cannot be supported by magnetostratigraphic data results of magnetostratigraphic correlation show that in the polish part of the central european basin the permian triassic boundary is close to the boundary between the uppermost zechstein and the lower buntsandstein it is located within the reversed magnetozone pzr1 identified in the upper part of the rewal formation in the german part of the central european basin the permian triassic boundary can be located within the reversed magnetozone zrz that covers most of the brockelschiefer a higher stratigraphic location of this boundatry i e inside the lowermost buntsandstein requires a reversed polarity record to be found within the basal triassic normal polarity zone

simulation and parameterization of the turbulent transport in the hurricane boundary layer by large eddies 1 hurricane boundary layer hbl processes especially the structure of the coherent large eddy circulations lecs and their induced vertical transport are not well understood this paper introduces a large eddy simulation les framework in a weather hindcasting mode developed from a multiple scale nested weather research and forecasting wrf model using the wrf les this study investigated the structure of the hbl lecs and the associated vertical transport during the landfall of hurricane ivan 2004 the simulation shows that the hbl lecs exist in a mean stable environment and consist of well defined updraft and downdraft statistically the hbl lecs are only slightly skewed with the updrafts and downdrafts relatively evenly distributed spatially the inversion base basically envelopes the upper boundary of lecs the trough in between two adjacent lecs is where most entrainment takes place whereas the crest of the lecs is where boundary layer air detrains out of the hbl in such a way lecs directly connect the surface the hbl and the main body of a hurricane vortex and enhance the exchange of energy moisture and momentum between them it is found that the current boundary layer schemes significantly underestimate the resolved turbulent fluxes due to the fact that the effects of lecs have not been included in the parameterizations on the basis of the statistical structure of lecs simulated by the wrf les this paper proposes a conceptual updraft downdraft model that can potentially be implemented in weather forecasting models to parameterize the fluxes induced by the hbl lec transport

a middle triassic paleomagnetic pole for the eurasian plate from heming france the paleomagnetic study of middle triassic limestones 91 cores 160 samples from a 40 m thick section in heming france yields a paleomagnetic pole for stable europe at lat 53 5 n lon 140 8 e dp 2 3 dm 3 9 this pole fills an important gap of the apparent polar wander path apwp of the eurasian plate the comparison of this pole with available data shows a standstill of the eurasian plate from the late paleozoic to the middle triassic followed by a rapid drift until the lower jurassic the beginning of the rapid drift is contemporaneous with the initiation of main rifting processes in the tethyan oceans

authigenic cadmium enrichments in suboxic sediments precipitation and postdepositional mobility the postdepositional mobility of cd and u has been investigated in north atlantic turbidites in order to validate their utility as proxies of paleo organic carbon fluxes in this region pelagic sediments are interspersed with relatively organic rich turbidites following instantaneous emplacement of turbidite units an oxidation front progressively migrated downwards into the suboxic turbidite thereby leading to redistribution of authigenic phases according to their affinity to different redox conditions authigenic cd concentrations show a large peak at the redox boundary and are significantly lower in the oxidized portion than in the deeper unoxidized part of the turbidite this distribution indicates that cd has been continuously remobilized by the oxidation front thereby suggesting high sensitivity of the cd species to the redox state and an efficient immobilization mechanism for cd under reducing conditions we propose the precipitation of cds as a plausible mechanism for removal of cd in reducing sediments rather than adsorption onto mineral surfaces this proposal is consistent with porewater data indicating diffusion of cd toward and uptake by suboxic sediments solubility calculations suggest that precipitation of cds may occur in suboxic sediments in the presence of trace levels of h2s below routine detection limits there is no evidence for release of cd or u back into seawater upon oxidation of reducing sediments the strong coupling between precipitation of authigenic cd and u and the early diagenetic degradation of organic carbon offers the potential of reconstructing paleo productivity using records of cd and u however postdepositional redistribution of authigenic cd and u may significantly alter records of authigenic cd and u thereby rendering paleo productivity reconstructions uncertain we propose that the cd u authigenic ratio may provide a qualitative indicator to assess the relative role of steady state incorporation relative to transient burn down enrichments

high resolution estimate for the depositional duration of the triassic latemar platform a new magnetostratigraphy and magnetic susceptibility cyclostratigraphy from basinal sediments at rio sacuz italy 1 a new magnetostratigraphy and magnetic susceptibility cyclostratigraphy from middle triassic basinal sediments at rio sacuz northern italy suggests a depositional duration of 1 myr for most of the 670 m carbonate latemar platform giving a high resolution estimate for the duration for the latemar s deposition the new magnetostratigraphy from rio sacuz clarifies the ambiguities in a previous magnetostratigraphic study of the latemar caused by lightning strike remagnetizations our rio sacuz study was unaffected by lightning using thermal demagnetization we show a normal reversed normal reversed sequence at the latemar correlated locality of rio sacuz with a polarity interval duration of 0 25 0 5 myr for the middle triassic this gives a depositional duration of 1 2 myr rock magnetic experiments show that the magnetic carrier is magnetite suggesting a primary depositional age remanence measurement of magnetic susceptibility at 1 m intervals from rio sacuz reveals eight short eccentricity cycles 95 125 kyr bundled into slightly more than two 405 kyr long eccentricity cycles indicating a more precise duration for the rio sacuz section of 0 8 to 1 myr the shorter depositional duration required by this study forces a sub milankovitch time scale of 1 2 kyr for the latemar platform s meter scale rhythmic bedding and provides strong evidence for nonorbitally driven climate change in the middle triassic

finescale dual doppler analysis of hurricane boundary layer structures in hurricane frances 2004 at landfall abstracttwo doppler on wheels dow mobile radars collected fine spatial scale dual doppler data in the right front quadrant and eye of hurricane frances 2004 as it made landfall near stuart florida a 5 7 km dual doppler baseline established a dual doppler domain south and east of fort pierce florida encompassing a 5 5 km 5 5 km horizontal area with a grid spacing of 20 m allowing for the resolution of subkilometer scale horizontal structures and associated kinematics three dimensional vector wind analyses of the boundary layer revealed the presence of linear coherent structures with a characteristic wavelength of 400 500 m near the surface that increased in size and became more cellular in shape with increasing height average horizontal perturbation winds were proportional to average total horizontal winds within the eye of the hurricane the features lost linear coherency despite a high mean wind speed possibly due to changes in stability a slight decrease in the characteristic wavelength

helical circulations in the typhoon boundary layer 1 low level wind data from the wsr 88d in guam obtained in typhoon dale 1996 and typhoon keith 1997 are analyzed for coherent structures consistent with the results of previous studies of atlantic hurricanes velocity anomalies associated with coherent structures were found in the boundary layer of both storms a total of 99 cases of coherent structures also known as roll vortices were documented during a 6 h evaluation period for each storm storm relative roll location roll vorticity asymmetries in the upward and downward momentum fluxes and signatures of circulations transverse to the mean flow associated with roll circulations were explored the effects of terrain and convective precipitation systems such as rainbands on the occurrence of rolls were investigated the results support and extend prior findings of roll observations and can be used to help validate theoretical and numerical models of coherent structures within tropical cyclones moreover the wind variations documented in this study may have application for wave runup and wind damage potential in tropical cyclones

the middle triassic magnetostratigraphy from the peri tethys basin in poland abstract the paper presents the first complete magnetic polarity scale obtained for the middle triassic of the northern peri tethys area the roetian and muschelkalk deposits of southern poland upper silesia the holy cross mountains were studied paleomagnetically the obtained paleopole a 52 n 143 e fits well to the middle triassic ca 240 ma segment of the stable european apwp a set of various quality characteristic directions isolated in 106 samples was used for construction of the composite polarity scale this peritethyan scale has been tied with conodont zonation and referred to the scale erected earlier in the tethyan realm comparison of both scales indicates that the whole roetian succession in the southern polish basin should be correlated with the latest olenekian the normal marine sedimentation ceased in the polish basin as early as in the late fassanian time the obtained magnetostratigraphic scale combined with the sequence stratigraphic framework enables a reliable chronological correlation of the late olenekian ladinian succession over the entire peri tethys basin

the biostratigraphic importance of conchostracans in the continental triassic of the northern hemisphere conchostracans or clam shrimp order conchostraca sars are arthropods with a carapace consisting of two chitinous lateral valves triassic conchostracans range in size from 2 to 12 5 mm long and are common in deposits that formed in fresh water lakes isolated ponds and brackish areas their dessication and freeze resistant eggs can be dispersed by wind over long distances therefore many conchostracan species are distributed throughout the entire north ern hemisphere in the late permian to middle triassic interval several of these forms are also found in gondwana many wide ranging conchostracan species have short stratigraphic ranges making them excellent guide forms for subdivision of triassic time and for long range correlations the stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits this makes con chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits upper triassic gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere in the norian some slight provincialism can be observed even within the northern hemisphere for example the sevatian redondestheria seems to be restricted to north america and acadiestheriella n gen so far has been found only in the sevatian deposits from the fundy basin of southeastern canada here we establish a con chostracan zonation for the changhsingian late permian to hettangian early jurassic of the northernhemispherethat forthemostpart isverywellcorrelatedwiththemarinescale thiszona tion is especially robust for the changhsingian to early anisian late ladinian to cordevolian and rhaetian to hettangian intervals for most of the middle and upper triassic this zonation is still preliminary five new genera six new species and a new subspecies of conchostracans are described that are stratigraphically important half of the eight stage boundaries of the triassic have been defined by a bio event within a marine global stratotype and point gssp locality and these definitions have been accepted by both the international subcommission on triassic stratigra phy and the international commission on stratigra phy the remaining four stage boundaries are nearing final definition in the lower triassic both the base of the induan priority brahmanian stage base of triassic and the base of the next younger olenekian stage have been firmly defined in the middle triassic there is wide agree ment that the defining species for the base of the anisian stage should be chiosella timorensis in the gssp candidate site at desli caira romania but there has not yet been a formal vote on this the base of the overlying ladinian stage however has been firmly defined in the upper triassic the base of the carnian has been firmly likewise defined but there is not yet a final defi nition for the boundaries of the overlying norian and rhaetian stages a consensus has not been reached on a defining species for the base of the norian or its gssp locality but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval for the base of the rhaetian misikella posthernsteini kozur mock has been chosen as the defining species by the international working group on the rhaetian stage and the gssp candidate locality at steinbergkogel austria has been studied in detail by a group under the leadership of l krystyn vienna and presented to the participants of the international conference on upper triassic sub divisions zonations and events in bad goisern in the autumn of 2008 the base of the overlying hettangian stage base of the jurassic has been defined so far only by a working group as the fad first appearance datum of psiloceras spelae guex taylor rakus bucher the final definition of the triassic stages within marine gssp sections will be completed in the near future but more than 50 of known triassic rocks are of continental origin therefore the main task of triassic stratigraphers in thefuture will besubdivid ing and correlating terrestrial strata both between

distribution of sedimentary organic matter in anisian carbonate series of s poland evidence of third order sea level fluctuations the stratigraphic distribution of sedimentary organic matter in anisian carbonate series of southern poland is studied with respect to relative sea level fluctuations palynofacies patterns clearly reflect transgressive regressive trends that are interpreted in terms of third order cyclicity major flooding phases are detected by maximum abundance of marine plankton in the upper bithynian and pelsonian transgressive and highstand deposits are recognized by changes in the terrestrial input of organic particles and the relative percentages and diversity of the plankton group the palynological data support the sequence stratigraphic interpretation based on sedimentological features and geochemical signatures the corresponding eustatic signals of sedimentary and organic facies are discussed the study highlights the potential of palynofacies analysis for sequence stratigraphical interpretation

variability of trace element uptake in marine reptile bones from three triassic sites s poland influence of diagenetic processes on the host rock and significance of the applied methodology abstract diagenetic alternation of apatite building vertebrate bioclasts is a complex process it is influenced by numerous factors but the impact of diagenetic processes affecting the host rock is commonly underestimated the present study aims at identifying the causes of different concentration levels and distribution patterns of ree and at examining the significance of the material chosen for normalisation we measured ree and other trace element concentrations in three bone assemblages of triassic marine reptiles using la icp ms and in the host rocks using icp ms two groups of hard parts reveal clearly different trace element contents and distribution patterns the remains from gogolin show a distinct mreen enrichment which must have been caused by replacement involving numerous substitutions that was possible due to a relatively high porosity of the host rocks and the presence of pore water the mreen enrichment and low concentrations of mg and sr combined with a relatively high content of u in these bones indicate solutions derived from meteoric water as the source of the incorporated ions the reductive dissolution of fe oxyhydroxides that are abundant in the host rock matrix and that likely were an important source of ree may have influenced and controlled the ree uptake the significant hreen enrichment over lreen as revealed in the rust coloured bones from raciborowice gorne is likely connected with local acidification of the pore water resulting from aqueous oxidation of pyrite infilling the pore spaces in the bones the material selected for normalisation of the chemical composition of apatite can have a significant impact on values of the normalised data used further for interpretations particularly when vertebrate bioclasts from carbonate host rocks are involved the carbonate rocks have element ratios that differ from those characterising the commonly used paas and nasc normalisation materials in particular ce anomaly values can distinctly vary depending on the applied normalisation procedure vertebrate hard parts that definitely spent more time in a host rock than in an animal body must be rigidly handled as a constituent of a specific rock never as a separate item

spectral characteristics of turbulence in the hurricane boundary layer over the ocean between the outer rain bands spectra and cospectra of wind velocity potential temperature and humidity have been analysed using data collected in the atmospheric boundary layer in hurricanes fabian 2003 and isabel 2003 during the coupled boundary layer air sea transfer cblast hurricane experiment the spectra and cospectra are normalized following the surface layer scaling methods according to similarity theory it is found that the cblast data gathered in the mixed layer between the outer rain bands below 400 m can be grouped into well defined curves for spectra of wind velocity potential temperature and humidity and for cospectra of momentum and humidity flux however the cospectra of sensible heat flux do not exhibit well defined universal shape the cblast universal shape spectra and cospectra generally resemble the shapes of those from previous studies but shift to higher frequencies that correspond to smaller wavelengths of turbulent eddies that contain most of the energy this work highlights the structural difference between the hurricane boundary layer and the standard atmospheric boundary layer over land and ocean copyright 2010 royal meteorological society

climatically related millennial scale fluctuations in strength of california margin oxygen minimum zone during the past 60 k y a strong oxygen minimum zone omz currently exists along the california margin because of a combination of high surface water productivity and poor intermediate water ventilation however the strength of this omz may have been sensitive to late quaternary ocean circulation and productivity changes along the margin although sediment lamination strength has been used to trace ocean oxygenation changes in the past oxygen levels on the open margin are not sufficiently low for laminations to form in these regions benthic foraminifera are highly sensitive monitors of omz strength and their fossil assemblages can be used to reconstruct past fluctuations benthic foraminiferal assemblages from ocean drilling program site 1017 off point conception exhibit major and rapid faunal oscillations in response to late quaternary millennial scale climate change dansgaard oeschger cycles on the open central california margin these faunal oscillations can be correlated to and are apparently synchronous with those reported from santa barbara basin together they represent major fluctuations in the strength of the omz which were intimately associated with global climate change weakening perhaps disappearing during cool periods and strengthening during warm periods these rapid major omz strength fluctuations were apparently widespread on the northeast pacific margin and must have influenced the evolution of margin biota and altered biogeochemicalmore cycles with potential feedbacks to global climate change less

the drift history of iran from the ordovician to the triassic new late ordovician and triassic palaeomagnetic data from iran are presented these data in conjunction with data from the literature provide insights on the drift history of iran as part of cimmeria during the ordovician triassic a robust agreement of palaeomagnetic poles of iran and west gondwana is observed for the late ordovician earliest carboniferous indicat ing that iran was part of gondwana during that time data for the late permian early early tri assic indicate that iran resided on subequatorial palaeolatitudes clearly disengaged from the parental gondwanan margin in the southern hemisphere since the late early triassic iran has been located in the northern hemisphere close to the eurasian margin this northward drift brought iran to cover much of the palaeotethys in approximately 35 ma at an average plate speed ofc 7 8 cm year 21 and was in part coeval to the transformation of pangaea from an irvin gian b to a wegenerian a type configuration

lineal eddy features under strong shear conditions abstract large eddy simulation of a marine boundary layer bl with strong wind shear and weak buoyancy flux over a relatively large horizontal domain 25 18 km and long time period 16 h produces lineal eddy structures with along axis variations these rolls are transient their lifetime being roughly 8 h and their horizontal to vertical aspect ratio increases with time at all heights above the surface layer even above the bl temporally coherent features propogate with a speed slightly slower than the vertically averaged bl velocity the length scale of along roll variation is about four and one half times the corresponding cross roll length scale to examine the importance of the roll circulations fluxes of momentum heat and water vapor are partitioned into roll and non roll contributions and additionally separated into contributions from the ascending and descending roll regions to reveal differences in advective roll transport and in roll modulation of smaller scale transfer the roll in

a multiscale numerical study of hurricane andrew 1992 part i explicit simulation and verification abstract in this study the inner core structures of hurricane andrew 1992 are explicitly simulated using an improved version of the penn state ncar nonhydrostatic two way interactive movable triply nested grid mesoscale model mm5 a modified betts miller cumulus parameterization scheme and an explicit microphysics scheme were used simultaneously to simulate the evolution of the larger scale flows over the coarser mesh domains the intense storm itself is explicitly resolved over the finest mesh domain using a grid size of 6 km and an explicit microphysics package containing prognostic equations for cloud water ice rainwater snow and graupel the model is initialized with the national centers for environmental prediction analysis enhanced by a modified moisture field a model generated tropical storm like vortex was also incorporated a 72 h integration was made which covers the stages from the storm s initial deepening to a near category 5 hurricane intensity and the landfall over florida as

nitrogen isotope and productivity variations along the northeast pacific margin over the last 120 kyr surface and subsurface paleoceanography 1 glacial interglacial changes in sedimentary 15n over the last 120 kyr display a remarkably similar pattern in timing and amplitude in core records extending from the denitrification zone in the eastern tropical north pacific etnp where subsurface denitrification is active to the oregon margin where no denitrification occurs today low 15n values 4 6 generally characterize glacial stages 2 and 4 and higher 15n values 7 10 are representative of the holocene millennial scale periods within stage 3 and stage 5 the inferred synchroneity of 15n variations along the entire margin implies that the nitrate isotopic signal produced in the oxygen poor subsurface waters in the etnp is rapidly advected northward and recorded at sites far beyond the boundaries of the modern denitrification zone similar to 15n primary production indicators percent corg ba al and percent opal show glacial interglacial as well as millennial scale variations along the ne pacific margin with higher primary production during warm periods however the relative phasing between 15n and paleoproduction tracers within individual records changes latitudinally whereas 15n and primary production vary approximately synchronously in the midlatitudes production lags 15n in the etnp by several kiloyears this lag calls for a new understanding of the processes driving denitrification in the etnp we suggest that oxygen input by the equatorial undercurrent as well as local organic matter flux controls denitrification rates in the etnp moreover the differences in relative timing point to a time transgressive development of upwelling favorable winds along the ne pacific margin after the last glaciation with those in the north developing several kiloyears earlier

high resolution simulation of tropical storm ivan 2004 in the southern appalachians role of planetary boundary layer schemes and cumulus parametrization the weather research and forecasting wrf model was used to simulate the evolution of tropical storm ivan 2004 in the southeast united states using both the yonsei university ysu and mellor yamada janjic myj boundary layer parametrizations in contrast to tropical cyclone tc simulations over the ocean the effect of the surface layer becomes secondary for a dissipating hurricane along its terrestrial track although these two schemes can reproduce ivan reasonably well our results suggest that the mixing properties for damped mechanical turbulent conditions weakly stable are strongly underestimated by both parametrizations this underestimation impacts the thermodynamic properties of the storm leading to significant differences in the storm areal extent and the simulated precipitation fields suggestions for further improvements are provided an evaluation of the impact of using or not using a convective parametrization specifically the kain fritsch kf scheme at 3 km grid spacing shows marginal impact on storm coverage intensity and precipitation except for the presence of widespread light rainfall in the piedmont east of the mountains when the kf is employed analysis of the thermal structure of the simulated storm indicates that in the inner storm region the kf is either not activated or primarily produces parametrized shallow convection as a result the net heating tendency associated with adiabatic and diabatic processes is almost unaltered inside the storm together with a nearly equivalent surface momentum sink leading to similar storm areal extent and intensity light rainfall to the east of the mountains can be due to the trigger mechanism of kf which depends on boundary layer convergence forcing parametrized deep convection near the coast where surface roughness changes enhance convergence

observed boundary layer wind structure and balance in the hurricane core part i hurricane georges abstract the gps dropsonde allows observations at unprecedentedly high horizontal and vertical resolution and of very high accuracy within the tropical cyclone boundary layer these data are used to document the boundary layer wind field of the core of hurricane georges 1998 when it was close to its maximum intensity the spatial variability of the boundary layer wind structure is found to agree very well with the theoretical predictions in the works of kepert and wang in particular the ratio of the near surface wind speed to that above the boundary layer is found to increase inward toward the radius of maximum winds and to be larger to the left of the track than to the right while the low level wind maximum is both more marked and at lower altitude on the left of the storm track than on the right however the expected supergradient flow in the upper boundary layer is not found with the winds being diagnosed as close to gradient balance the tropical cyclone boundary layer model of kepert and wan

is pore water oxygen content decoupled from productivity on the california margin trace element results from ocean drilling program hole 1017e san lucia slope california 1 trace element evidence from the california margin ocean drilling program hole 1017e shows significant changes in sediment redox chemistry at intermediate water depths over the last 60 kyr the influence of export production on intermediate water oxygen content can be distinguished from lateral ventilation through comparisons among proxies representing export production flux percent corg and sediment surface i br and pore water mo ag cd re and u oxygenation proxies sulfate reduction within the uppermost sediment column occurred during late quaternary interstadials and the holocene indicating reduced intermediate water ventilation however sulfate reduction was most intense during major interstadials when productivity was enhanced decoupling between export production and pore water oxygen content is demonstrated during deglaciation when the sediment pore water oxygen content increases without a corresponding reduction in export productivity thus both export production and intermediate water ventilation play a role in oxygen minimum zone processes on the california margin

genesis of the lower triassic bonebeds from gogolin s poland the impact of microbial mats on trapping of vertebrate remains abstract three bone bearing horizons consisting of seven bone bearing beds with fish and reptile remains were recently discovered in the uppermost rot buntsandstein lower triassic peritidal and shallow marine carbonates in the vicinity of gogolin s poland the aim of this study is to recognize the genesis and depositional environments of the bonebeds detailed fieldwork microfacies analysis and sem eds analysis reveal that the vertebrate remains occur to a great extent alongside evidence for former microbial activity the reptile remains represent at least dactylosaurus and nothosaurus sauropterygia genera while the fish remains belong to the chondrichthyes and actinopterygii the vertebrate remains were deposited in a transitional zone between the costal sabkha and the epicontinental sea the first bone bearing horizon originated in the most landward setting in the uppermost intertidal zone likely at the margins of a pond or coastal lagoon the second bone bearing horizon was formed in the upper intertidal zone the vertebrate remains of the third bone bearing horizon were accumulated in two different settings in the lower intertidal zone in a small palaeopond and in the subtidal zone in a protected back shoal lagoon three bone accumulations occur within planar stromatolites while the other bone bearing beds reveal more indirect evidence for former microbial activity in our opinion the presence of the sticky microbial mats in the intertidal settings was the crucial factor that allowed the establishment of and controlled these accumulations of vertebrate remains the soft gluey substrates trapped vertebrate remains that were transported across them once trapped the vertebrate bioclasts were efficiently immobilized and thus protected against damage due to sedimentological agents the lack of any orderly arrangement of the vertebrate bioclasts suggests that they may have been delivered to the individual mat surfaces by diverse media from various directions and also at different times

high frequency depositional cycles in the muschelkalk middle triassic of southern poland origin and implications for germanic basin astrochronological scales abstract high frequency depositional cycles are often used for long distance correlations within sedimentary basins and constructing high resolution chronostratigraphic scales calibrated to the orbital clock such an approach has been used for the tropical epicontinental muschelkalk sea covering most of europe in the middle triassic this paper aims at establishing the spatial extent and internal architecture of shallow marine muschelkalk cycles within a small 120 by 50 km area of the germanic basin to identify their local vs regional distribution and cycle forming mechanisms three groups of cycles are distinguished 1 peritidal cycles representing a tidal flat lagoon system which experienced longer periods of emersion 2 shallow subtidal cycles formed around the fair weather wave base and 3 deep subtidal cycles developed around the storm wave base the three cycle types differ markedly in the composition facies homogeneity sedimentary trends hierarchical organization continuity and degree of lateral changeability and complexity which collectively translates into the ease of cycle recognition despite the differences the defined cycles do not extend laterally beyond the studied area and have laterally variable facies heterogeneities sedimentary trends and thicknesses this variability resulted from more or less mosaic infilling of accommodation space reflecting local bathymetry physicochemical conditions and carbonate production and accumulation rates on the platform accommodation space evolved by the interplay of eustatic sea level fluctuations regional subsidence and synsedimentary tectonic block movements but the contribution of these factors changed over time and was to varying degrees masked for each of the three cycle types by intrinsic sedimentary processes the study shows that middle triassic cycles of the germanic basin have a local to sub regional distribution and thereby are inappropriate for basin wide correlations and chronostratigraphic inferences it also strengthens the opinion of several workers that correlation of idealized cycles is unrealistic without checking the horizontal continuity of facies and key surfaces directly in the field

coprolites of marine vertebrate predators from the lower triassic of southern poland abstract numerous coprolites are described for the first time herein from the lower triassic olenekian shallow marine sedimentary rocks in southern poland x ray diffraction and geochemical analyses show that they are preserved as calcium phosphate with small admixtures of quartz and calcite additionally sem and thin section studies revealed that they contain highly fragmented faunal remains crinoids molluscs and vertebrates the size shape geochemistry biostratigraphic distribution and co occurrence with vertebrate skeletal remains imply that the coprolites at hand were likely produced by nothosaurids the durophagous sauropterygian reptiles and actinopterygian ray finned fish the large number of recorded coprolites implies that durophagous predation has been intense during the early triassic and suggests that the so called mesozoic marine revolution probably started soon after the end permian extinction furthermore discovery of sinusoidal trails attributable to nematodes in some coprolites implies that the intestinal parasitic associations with these predators had already evolved by at least the early triassic

mobility of authigenic rhenium silver and selenium during postdepositional oxidation in marine sediments sedimentary records of redox sensitive trace elements hold significant potential as indicators of paleoceanographic environmental conditions records of re can reveal the intensity of past reducing conditions in sediments at the time of deposition whereas records of ag may record the magnitude of past diatom fluxes to the seafloor confidence in paleoenvironmental reconstruction from records of either metal however requires it to have experienced negligible redistribution since deposition this study examines diagenetic rearrangements of re and ag that occur in response to exposure to bottom water o2 in environments of low sedimentation rate including madeira abyssal plain turbidites and eastern mediterranean basin sapropels authigenic re was remobilized quantitatively by oxidation but poorly retained by the underlying sediments all records are consistent with previous work demonstrating that only a limited reimmobilization of re occurs preferentially in corg rich reducing sediments silver was also mobilized quantitatively by oxidation but it was subsequently immobilized more efficiently in all cases as sharp peaks immediately into anoxic conditions below active oxidation fronts and these peaks remain immobile in anoxic conditions during long term burial comparison of ag s and se records from various cores suggests that ag is likely to have been immobilized as a selenide a mechanism previously proposed for hg in similar situations mercone et al 1999 coexisting narrow peaks of ag and hg with se offer a means of assessing whether oxidative burndown has ever occurred at the top of corg and sulfide rich sedimentary units although these results suggest that caution must be used when inferring paleoenvironmental information from records of ag and re in cores with low sediment accumulation rates 5 cm ka 1 they should not affect the promise that authigenic ag and re records hold for paleoenvironmental reconstruction in sediments with higher accumulation rates and where anoxic conditions have been maintained continuously

analysis of marrow cavity fillings as a tool to recognise diverse taphonomic histories of fossil reptile bones implications for the genesis of the lower muschelkalk marine bone bearing bed middle triassic żyglin s poland abstract the bone bearing bed from yglin s poland which likely represents the oldest lower muschelkalk accumulation of reptile remains in the se part of the germanic basin has been investigated in order to determine its genesis the basic methods were supported by petrographic analysis of the marrow cavity and large inter trabecular pore space fillings of fossil bones which was used to check its usefulness to identify the environments where the bones were initially deposited and to decipher taphonomic histories of the remains the bone bearing bed is a composite deposit which consists of three distinct layers from bottom to top micritic limestone mudstone bioturbated autochthonous mud crinoidal limestone grainstone to packstone calcirudite and shell rich limestone packstone to wackstone calcirudite the crinoidal limestone layer the main bone bearing bed is recognised as the proximal tempestite deposited in the mid ramp zone the petrographic analysis of the fillings reveals the prevalence of minute ostracod carapaces accompanied by other grains embedded together with micrite to microspar such compositions suggest that these sediments may have been inserted into the bone pore spaces in lagoons and tidal flat ponds features of some bones record their early diagenetic burial and lithification before the final redeposition the isopachous spar blocky spar and weathered pyrite document changes in the chemical composition of fluids that flowed into the bone interiors the burrow found in the marrow cavity of specimen iguam zov 7 provides evidence that some remains were inhabited by minute or juvenile invertebrates all recognised features indicate that both invertebrate and vertebrate bioclasts included in the tempestite were initially deposited in various settings of the carbonate ramp and in the end redeposited as a result of a heavy storm or a hurricane the examined bone bearing bed represents time averaged assemblage which originated due to hydraulic concentration of the vertebrate bioclasts the petrographic analysis of the fillings is a valuable tool to identify complex taphonomic pathways of vertebrate bioclasts

an observational case for the prevalence of roll vortices in the hurricane boundary layer abstract doppler velocity data from weather surveillance radar 1988 doppler wsr 88d radars during four hurricane landfalls are analyzed to investigate the presence of organized vortices in the hurricane boundary layer hbl the wavelength depth magnitude and track of velocity anomalies were compiled through analysis of doppler velocity data the analysis reveals alternating bands of enhanced and reduced azimuthal winds closely aligned with the mean wind direction resulting statistics provide compelling evidence for the presence of organized secondary circulations or boundary layer rolls across significant areas during four hurricane landfalls the results confirm previous observations of the presence of rolls in the hbl a potential limitation of the study presented here is the resolution of the wsr 88d data in particular analysis of higher resolution data e g from the doppler on wheels is needed to confirm that data aliasing has not unduly impacted the statistics reported here momentum flux

numerical study of convection observed during the winter monsoon experiment using a mesoscale two dimensional model abstract a two dimensional version of the pennsylvania state university mesoscale model has been applied to winter monsoon experiment data in order to simulate the diurnally occurring convection observed over the south china sea the domain includes a representation of part of borneo as well as the sea so that the model can simulate the initiation of convection also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle this allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck which typically occupies several hundred kilometers of the domain frank and cohen s cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area the major conclusions are ice phase processes are important in determining the level of maximum large scale heating and vertical motion because there is a strong anvil componen

high resolution upb dating of middle triassic volcaniclastics time scale calibration and verification of tuning parameters for carbonate sedimentation abstract we report high resolution single zircon u pb age data for middle triassic volcaniclastic intercalations in biostratigraphically calibrated pelagic successions of the southern alps the results require a redefinition of the chronometric scale for the middle triassic moreover they do not support current models relating cyclic sedimentation in platform carbonates of the dolomites to orbital tuning tight concordant age clusters were obtained for five volcaniclastic layers in three ammonoid biozones of late anisian to early ladinian age two layers in the nevadites secedensis zone yielded identical mean 206 pb 238 u ages of 241 2 0 8 0 8 ma and 241 2 0 8 0 6 ma errors given at the 95 confidence level a layer in the gredleri zone is dated at 238 8 0 5 0 2 ma and two horizons in the archelaus zone yield similar ages of 237 9 1 0 0 7 ma and 238 0 0 4 0 7 ma these results are significantly older than the age values of 233 235 ma assigned to the anisian ladinian boundary by several current time scales 1 4 moreover our estimate of 240 7 241 3 ma depending on biostratigraphic collocation for the anisian ladinian boundary casts doubts on the reliability of age values of 245 250 ma proposed by most time scales for the permian triassic boundary the occurrence of pelagic fossils in basinal sediments as well as in age equivalent shallow marine middle triassic platform carbonates in the dolomites allows the sedimentary sequences of both environments to be correlated the 800 m thick latemar platform western dolomites is characterized by cyclic stacking patterns which have been interpreted as results of milankovitch type high frequency low amplitude sea level fluctuations the 12 m y interval of platform growth postulated from the assignment of orbital periodicities to the platform carbonate cycles 5 6 is in conflict with a maximum time span of 4 7 m y allowed by the present zircon data

multiplatform observations of boundary layer structure in the outer rainbands of landfalling typhoons this paper analyzes data collected from a new set of observational platforms in the coastal area of china which consist of a mobile observation system meteorological tower automatic weather station and doppler radars to investigate the mean and turbulent boundary layer structure and evolution during the landfall of typhoons an example of these data is provided from typhoon morakot 2009 vertical profiles of wind velocities and thermodynamic parameters from the observed data allow us to identify different boundary layer structures during and after landfall these structures sampled in regions of the outer core are stratified into periods where convection is occurring termed convective and periods where convection has recently 2 h occurred termed postconvective data analyses show that the thermodynamic mixed layer depth and inflow layer depth are higher during the convective period than the postconvective period the mixed layer depth is found to be within the strong inflow layer but the height of the maximum tangential wind speed is above the inflow layer during both periods contrary to recent observational studies of the boundary layer structure of tropical cyclones over water high frequency wind data show that momentum flux turbulent kinetic energy tke and integral length scales of wind velocities are all much larger during the convective period than the postconvective period the results suggest that convective downdrafts may play an important role in modulating turbulent flux tke vertical mixing and boundary layer recovery processes