a critical evaluation of bone weathering as an indication of bone assemblage formation abstract weathering of bones has been defined as chemical and mechanical deterioration and destruction occurring over time the periodic system of solar years actualistically documented correlations between the years since animal death and weathering stages and between weathering stages and depositional habitats lead to hypothesized relationships between prehistoric weathered bones and exposure and accumulation histories of those bones detailed review of those hypothesized relationships reveals accumulation and exposure histories are not readily inferred from assemblages of weathered bones the relationships minimally involve assuming the values of one or more kinds of taphonomic time which can at best be measured at ordinal scales simulated accumulation histories and inspection of actualistic data indicate an assemblage of weathered bones may be formed in various ways control of skeletal element type and interdependence taxon depositional environment and subsurface weathering are serious analytical challenges seldom fully met thereby rendering interpretations of weathered bones debatable

the procedure used to develop a coal char classification commission iii combustion working group of the international committee for coal and organic petrology abstract this paper describes an assessment of char classification system by the combustion working group in commission iii of the international committee for coal and organic petrology iccp the work of the group culminated in the production of a char atlas after a final round robin exercise this round robin involved 21 analysts and was an electronic exercise using digitally captured images of individual char particles rather than actual char blocks a software program featuring 170 char images was specifically designed to allow operators to identify each char based on a classification system with 9 individual char types tenuisphere crassisphere tenuinetwork crassinetwork mixed porous mixed dense fusinoid solid and mineroid the program electronically recorded all decisions as well as the time taken for each decision to be made from 170 chars 128 chars were identified by a majority 70 and these chars were then compiled in a char atlas that is now available for download www nottingham ac uk eczehl charatlas as would be expected all analysts appeared to become more confident in identifying chars during the exercise taking less time per image but with no clear evidence of improvement without exception analysts took longer to make an incorrect decision

radiation and self ignition induced alterations of permian uraniferous coal from the abandoned novator mine waste dump czech republic abstract the effects of uranium mineralization and self burning processes on inorganic and organic components of coal have been studied at a waste pile of the former novator coal and uranium mine at beckov intrasudetic basin czech republic in order to characterize physical and chemical properties of wastes as a basis for further environmental studies unaltered bituminous coal was composed predominantly of vitrinite with random reflectance values between 0 72 and 0 86 and inertinite less common liptinite macerals and a low level of organic solvent extractable material 0 01 1 33 wt uranium minerals caused local radioactive alterations in the uranium enriched coal matrix the diameter of rounded radiation induced haloes ranged from 0 35 to 100 m with higher reflectance 0 84 3 44 compared with bulk coal structural changes in radiation induced altered organic coal matter were characterized by low values of raman band disorder fewer aliphatic c h bonds and higher levels of oxygenated functional groups in micro infrared spectra zones of higher reflectance were also confined to veinlets of epigenetic chalcopyrite galena and sphalerite mineralization oriented perpendicularly to the coal bedding the methylnaphthalene ratios mnr of extracted organic matter correlated with uranium concentrations in individual samples in self ignition affected samples the higher reflectance 1 31 1 71 and values of raman band disorder mirrored the intensity of burning processes organic matter samples located at unburnt and burnt coal interfaces were composed of a mixture of coal macerals char and solid bitumens in the waste heap burning zone coal and claystone were transformed to clinkers composed of plagioclase pyroxenes tremolite hematite magnetite anatase and aluminosilicate glass or to paralava formed by porous cordierite and hematite organic components in the burnt out zone were represented by small dense and massive coke particles with reflectance of 4 48 fusinite with reflectance of 3 05 and rare coke droplets of solid bitumen r 1 90 only traces of phenanthrene and alkanes were identified in organic extracts of burnt out rock

biomarkers as proxies for plant inputs to peats an example from a sub boreal ombrotrophic bog lipid distributions in modern peat forming plants were determined and compared to biomarkers recovered from a ca 2800 year old peat deposited in a dutch ombrotrophic bog the peat section spans a well constrained shift in local hydrology and vegetation and potential molecular proxies for plant inputs were directly tested against the macrofossil record based on the analyses of modern plants low molecular weight lmw n alkanes c23 c25 and high molecular weight n alkanes c33 are proposed as potential biomarkers for sphagnum and non sphagnum inputs respectively consistent with this in the bargerveen peat core lmw n alkane abundances increase and hmw n alkane abundances decrease coincident with the shift to sphagnum dominated peat additional potential proxies include the abundances of c22 alkanedioic acid and phytenyl phytenoate as sphagnum indicators and the abundances of the triterpenoids taraxer 14 ene and taraxast 20 ene as biomarkers for ericaceae rootlets

organic geochemical study of sequences overlying coal seams example from the mansfield formation lower pennsylvanian indiana abstract roof successions above two coal seams from the mansfield formation lower pennsylvanian in the indiana portion of the illinois basin have been studied with regard to sedimentary structures organic petrology and organic geochemistry the succession above the blue creek member of the mansfield formation is typical of the lithologies covering low sulphur coals 2 the transgressive regressive packages above both seams reflect the periodic inundation of coastal mires by tidal flats and creeks as inferred from bioturbation and sedimentary structures such as tidal rhythmites and clay draped ripple bedforms geochemistry and petrology of organic facies above the blue creek coal suggest that tidal flats formed inland in fresh water environments these overlying fresh water sediments prevented saline waters from invading the peat contributing to low sulphur content in the coal above the unnamed coal trace fossils and geochemical and petrological characteristics of organic facies suggest more unrestricted seaward depositional environment the absence of saline or typically marine biomarkers above this coal is interpreted as evidence of very short periods of marine transgression as there was not enough time for establishment of the precursor organisms for marine biomarkers however sufficient time passed to raise so42 concentration in pore waters resulting in the formation of authigenic pyrite and sulphur incorparation into organic matter

dynamical aspects of the october storm 1987 a study of a successful fine mesh simulation a diagnostic study of a successful numerical simulation of the october storm 1987 is described this good non operational forecast was obtained using the meteorological office s fine mesh model run from a revised analysis at 00 gmt on 15 october 1987 the meteorological office s mesoscale model was also run using initial conditions at 12 gmt 15 october obtained by interpolating the above fine mesh forecast fields to examine the benefits of very high horizontal resolution 15km grid length diagnostic maps and cross sections derived are used to address two scientific issues i the role of weak moist slantwise stability or alternatively positive slantwise convective potential energy ii the dynamical significance of the striking cloud structure the cloud head seen in the satellite imagery early in the storm s life it appears that the baroclinic zone in which the storm develops is highly receptive to forcing by an upper trough and the warm boundary layer air just ahead of the main surface front is characterized by substantial slantwise convective available energy the cloud head is identified with a region of intense slantwise ascent in the warm air just above the main frontal zone its great meridional extent is associated with the upper tropospheric outflow and horizontal spreading of air which has recently undergone rapid slantwise ascent the low level temperature field exhibits throughout the development period a remarkable shape preserving thermal ridge of considerable intensity the sensitivity of the forecast to the removal of surface energy fluxes and latent heat of condensation are investigated separately it is found that on the timescale of the simulation surface energy fluxes have negligible impact on the explosive development on the other hand the contribution of latent heat release to the development appears to dominate the dry baroclinic instability process

assessment of conditional symmetric instability from global reanalysis data abstractslantwise convection the process by which moist symmetric instability is released has often been linked to banded clouds and precipitation especially in frontal zones within extratropica

burning of coal waste piles from douro coalfield portugal petrological geochemical and mineralogical characterization abstract in the douro coalfield anthracites were exploited for decades 1795 1994 besides many small mines douro coalfield had two principal mining areas s pedro da cova and pejao coal mining activities cause several impacts on the environment one of which is the amount of discard or waste which was disposed of all over douro coalfield resulting in one of the most significant and severe impacts on the environment over 20 waste piles exist in the old mining areas geographically dispersed and three of them are presently burning their ignition was caused by forest fires during the summer of 2005 samples from the burning and unburned zones of the waste piles were studied as were the gas from vents and the minerals resulting after combustion geochemical processes and mineralogical transformations in the burning coal waste pile were investigated microscopic analyses of the samples identified some particular aspects related with combustion oxidation of pyrite the presence of iron oxides organic particles with cracks and rims with lowered suppressed rr devolatilization vacuoles and some char structures the occurrence of vitreous glassy material as well as fe al spinels in the burning coal waste provide evidences that the combustion temperature could have reached values above 1000 c due to combustion and as expected the samples studied reported high ash yields samples taken from the burning zones reported an increase of as cr li nb ni pb rb sr and lree concentrations and a decrease in zr and hree concentrations enrichment in cs li and rb was noted when comparing with the geochemical composition of black shales and world coals composition that is related with the contribution of granitic rocks in the sediments that originated the main lithologies of the douro coalfield carbonaceous shale and lithic arenites cluster analyses r type and q type were performed to understand the trend between the unburned and burning samples and it seems that some chemical variations are responsible for this separation elemental sulphur and salammoniac ammonium salt are the coal fire gas minerals neoformed on the surface of piles near the burning zones they were identified by different techniques mainly sem edx xrd and ftir relatively high concentrations of several aromatic compounds were detected in the gas collected at the studied areas as well as aliphatic hydrocarbons the highest concentrations of aromatic hydrocarbons were measured in gas samples from s pedro da cova waste pile the exposure to hazardous compounds present in the gas is a serious risk to human health and the environment

holocene bison diminution on the snake river plain idaho usa researchers have established a holocene pattern of bison spp diminution on the great plains of north america this pattern however is less clear west of the rocky mountains this lack of clarity stems from a relative paucity of paleontological and archaeological bison assemblages sufficiently large enough to understand local bison diminution to begin filling this important gap in knowledge we analyze a large bison assemblage from baker cave a late holocene archaeological site located on idaho s snake river plain measurements of humeri radii tibiae metatarsals and calcanei demonstrate that these animals were significantly smaller than early holocene bison from both the great plains and snake river plain middle holocene bison from the great plains are generally larger than those from baker cave but this size difference varies by skeletal element the baker cave bison do fall within the range of late holocene morphological variation present in both snake river plain and great plains bison popula

reconstruction of the late pleistocene grassland of the columbia basin washington usa based on phytolith records in loess abstract silica phytoliths preserved in three loess sections in southeastern washington state revealed a 100 000 year history of the columbia basin grassland changes in the proportion of different morphotypes indicate large shifts in vegetation composition during the last 100 ka a low elevation section 677 m asl near the center of the basin provided a record of alternating xeric festuca poa and mesic festuca koeleria grassland the middle slope section 1095 m asl supported picea abies or pinus ponderosa forest or non analog parkland at different times some trees were present at or near the site even during the last glacial maximum the highest site 1220 m asl supported stipa festuca and poa dominated grassland with some artemisia shrub during most of the late pleistocene but supports a coniferous forest today variations in vegetation can be explained as a response to changes in large scale climatic controls grasslands and shrub steppe were apparently more widespread and forests more restricted than today during the marine isotope stages 2 and 4 probably as a result of cooler and drier conditions the three new records are well correlated with previously published paleo reconstructions based on phytolith cicada burrow and stable isotope data from a nearby kp 1 loess section carp lake pollen record and global ice volume variations

the timing of late pleistocene mammalian extinctions in north america more than 375 14c dates from 150 fossil sites in north america have been analyzed to evaluate the question of extinction of late pleistocene megafauna when critically evaluated no 14c ages for any extinct pleistocene genera are younger than 10 000 yr b p

paleoenvironmental implications of two relative indicator rodent taxa during the pleistocene to holocene transition in south eastern washington state usa local pollen data diminution of body size of three ungulate species and decreased mammalian richness and evenness all indicate grass decreased in abundance during the pleistocene holocene transition pht in eastern washington state usa this paleoenvironmental history suggests that the abundance of remains of microtus sp should decrease as remains of peromyscus maniculatus increase in abundance during the pht these two taxa have well known ecologies relative to one another pht sediments at the marmes archeological site in south eastern washington state are sorted into three chronologically sequent isotaphonomic analytical units relative abundances of remains of microtus sp and p maniculatus shift across the analytical units in the predicted manner whether raw abundances or rarified abundances are considered these results suggest relative abundances of remains of microtus sp and p maniculatus recovered from other sites may be used as relative indicators of paleohabitats their abundances at homestead cave utah shift as predicted from the late pleistocene through the early holocene copyright 2014 john wiley sons ltd

mesoscale analysis of arc rainbands in a dry slot a series of almost concentric are shaped narrow rainbands was observed travelling at 140 km h 1 and producing severe wind gusts over parts of england their structure and environment have been analysed using radar and satellite imagery mesoscale model diagnostics surface observations and additional rawinsonde ascents obtained during the fronts and atlantic storm track experiment fastex the multiple rainband event is shown to have been associated with part of a dry intrusion characterized by a mesoscale vortex cold pool the event occurred within the dry slot region of a small frontal cyclone where the mesoscale pool of cold dry air was overrunning warm sector air continuous wind profiles from a uhf radar together with a well located rawinsonde at the epicentre of the arc rainbands showed that the major anomaly in the cold pool was an area of locally stronger winds 40 m s 1 at 800 hpa colocated with the temperature minimum at that level the observed orientation of the rainbands is explained in terms of the cold frontal structure at this level triggering ascent of the underlying warm moist air the multiple nature of the arc rainbands remains unexplained the possibilities of mesoscale gravity waves and conditional symmetric instability are both considered

the organic geochemistry of coal from plant materials to coal coalification is a process that transforms plant remains under the influence of time temperature and possibly pressure to a black generally lustrous solid organic fossil fuel having a very complex chemistry although much has been learned in the past two centuries on coal chemistry we still have little knowledge of the way plant materials undergo these transformations the problem has been the existence of adequate characterization tools the advent of some new tools for structural elucidation of macromolecules has led to some revised thinking on coalification originally thought to be a process involving the full degradation of plant remains and subsequent reconstitution of these remains the general consensus today is that the process involves a selective preservation of certain resistant plant components followed by some minor reorganization of the biopolymers that survive the major components of plants do degrade and the resistant ones often constitute only a small fraction of the original mass of the plant materials this paper examines the most recent literature concerning coalification and focuses on the chemistry associated with coalification of certain recognizable plant remains that have been at the center of research activity for the past two decades thus we examine the recent knowledge of the chemistry of resistant biopolymers in extant and fossil wood cuticles resins spores and algae knowledge that has been assembled to establish the reaction pathways towards coal macromolecules

isotopic evidence for temporal variation in proportion of seasonal precipitation since the last glacial time in the inland pacific northwest of the usa abstract large scale atmospheric circulation patterns determine the quantity and seasonality of precipitation the major source of water in most terrestrial ecosystems oxygen isotope 18o dynamics of the present day hydrologic system in the palouse region of the northwestern u s a indicate a seasonal correlation between the 18o values of precipitation and temperature but no seasonal trends of 18o records in soil water and shallow groundwater their isotope values are close to those of winter precipitation because the palouse receives 75 of its precipitation during winter palouse loess deposits contain late pleistocene pedogenic carbonate having ca 2 to 3 higher 18o values and up to 5 higher carbon isotope 13c values than holocene and modern carbonates the late pleistocene 18o values are best explained by a decrease in isotopically light winter precipitation relative to the modern winter dominated infiltration the 13c values are attributed to a proportional increase of atmospheric co2 in soil co2 due to a decrease in soil respiration rate and 13c discrimination in plants under much drier paleoclimate conditions than today the regional climate difference was likely related to anticyclonic circulation over the pleistocene laurentide and ice sheet

biomarkers and aromatic hydrocarbons in bituminous coals of upper silesian coal basin example from 405 coal seam of the zaleskie beds poland abstract this paper presents the geochemical characteristics of hard coals from the 405 coal seam found in several mines in the upper silesian coal basin poland the coals classifying as of medial coalification types d and c and as para and orthobituminous coals show variable technical chemical and petrographic properties vitrinite reflectance values range from 0 65 to 1 24 cdaf from 79 2 to 88 3 wt and vdaf from 23 7 to 37 4 wt maceral composition in all of the coals studied is dominated by vitrinite macerals 43 5 74 0 gas chromatography mass spectrometry was applied to assess organic matter sources and ranks using several biomarker and aromatic hydrocarbon parameters distributions of n alkanes acyclic isoprenoids diterpenoids steranes and triaromatic steroids indicate that the organic matter in the coals analysed is derived mostly from terrestrial vascular plants the biogenic organic matter was deposited mostly in an estuarine deltaic environment with a normal to low water level in a few cases a marine lagoonal or paludal environment is possible tetracyclic diterpanes such as phyllocladanes and kauranes indicators of the podocarpaceae and araucariceae families are explained by proposing input of organic matter deriving from voltziales plants which may have been able to synthesise these compounds biomarker and aromatic hydrocarbon parameters of thermal maturity in the coals show a clear correlation to vitrinite reflectance values and carbon content indicating degrees of thermal maturity in the range from early to advanced catagenesis frictional heat related to the klodnica fault movement caused aberrations in values of aromatic hydrocarbon maturity parameters in coals sampled

the impact of water washing biodegradation and self heating processes on coal waste dumps in the rybnik industrial region poland abstract water washing biodegradation and self heating impacts on coal waste features were investigated on four sample sets fresh coal wastes sampled less than one week after dumping samples from gullies in coal waste dumps self heated material and bierawka river sediment mixed with coal coal waste particles rock eval pyrolysis petrography and gas chromatography mass spectrometry gc ms were applied to assess degree of organic matter alteration it was found that water washing and self heating did not influence the vitrinite reflectance rock eval pyrolysis results better reflected the secondary changes in organic matter namely s 2 toc and hi t max allowed their extent to be defined changes were noted in other geochemical e g n alkane parameters 2 1 increased and n c 23 n c 31 decreased whereas pr ph pr n c 17 and ph n c 18 ratios increased slightly compared to fresh coal waste the hunt diagram allows discrimination between water washed and biodegraded samples from unaltered fresh coal waste similarly changes in distributions of phenols alkyl aromatic hydrocarbons and polycyclic aromatic hydrocarbons pahs reflect degree of water washing self heating strongly affects distributions of some biomarkers such as n alkanes pr and ph whereas pentacyclic triterpane distributions were generally well preserved phenols occur in greatest amount in self heated wastes probably released from heated vitrinite domination of 2 3 ring pah rings indicated the bitumen precipitation zone and well differentiated burnt out wastes recent organic matter input is seen in increased cpi carbon preference index values

scape charts from numerical weather prediction model fields abstract although the scape concept is strictly only meaningful for quasi two dimensional flows it can be given a precise definition for flows satisfying the conditions governing the semigeostrophic approximation for this type of balanced flow it is argued that scape corresponds to the positive area on the tephigram when the environment curve defines the thermodynamic state along a semigeostrophic vortex line a procedure for the calculation of scape as a numerical model diagnostic is described and is applied to an operational model analysis prior to the great storm which struck southern england on 16 october 1987 values of scape greater than 1000 j kg 1 are found over a large area near the embryo storm since the degree of slantwise stability or instability is widely considered to be relevant to the intensity of cyclogenesis and rainband formation scape charts may be of some utility to the bench forecaster

conditional symmetric instability in sting jet storms sting jets are transient mesoscale jets of air that descend from the tip of the cloud head towards the top of the boundary layer in severe extratropical cyclones and can lead to damaging surface wind gusts this recently identified jet is distinct from the well documented jets associated with the cold and warm conveyor belts one mechanism proposed for their development is the release of conditional symmetric instability csi here the spatial distribution and temporal evolution of several csi diagnostics in four severe storms are analysed a sting jet has been identified in three of these storms for comparison we also analysed one storm that did not have a sting jet even though it had many of the apparent features of sting jet storms the sting jet storms are distinct from the non sting jet storms by having much greater and more extensive conditional instability ci and csi csi is released by ascending air parcels in the cloud head in two of the sting jet storms and by descending air parcels in the other sting jet storm by contrast only weak ci to ascending air parcels is present at the cloud head tip in the non sting jet storm csi released by descending air parcels as diagnosed by decaying downdraught slantwise convective available potential energy dscape is collocated with the sting jets in all three sting jet storms and has a localised maximum in two of them consistent evolutions of saturated moist potential vorticity are found we conclude that csi release has a role in the generation of the sting jet that the sting jet may be driven by the release of instability to both ascending and descending parcels and that dscape could be used as a discriminating diagnostic for the sting jet based on these four case studies copyright 2011 royal meteorological society and british crown copyright the met office

balanced flow states resulting from penetrative slantwise convection abstract analytic solutions representing rectilinear flow in geostrophic and hydrostatic balance are constructed using the conformal mapping technique of gill two types of mapping are used to characterize the state of a fluid after a parcel convects to a position of neutral buoyancy the first mapping corresponds to the homogeneous intrusion in a rotating stratified fluid studied by gill the second mapping describes an internal discontinuity of finite length embedded in a fluid of uniform potential vorticity in the idealized physical problem represented by these conformal transformations an elliptical region of undisturbed fluid is considered to be saturated and in a state of unstable equilibrium on perturbing the system the saturated parcel convects to a new level distant from its initial position and is rendered homogeneous in absolute momentum and potential temperature by internal mixing the resulting equilibrium configuration involves a two dimensional fluid lens which 1ocally distorts the

taphonomy pathology and paleoecology of the terminal pleistocene marmes rockshelter 45fr50 big elk cervus elaphus southeastern washington state usa in 1968 remains of what were reported to be a larger than modern elk cervus elaphus were recovered from terminal pleistocene sediments associated with the marmes rockshelter archaeological site in southeastern washington state originally thought to have been butchered by humans it is associated with radiocarbon dates suggesting an age of about 9800 14 c years b p taphonomic analysis in 2009 indicates the elk likely died of natural causes during winter months it was lightly scavenged by carnivores prior to burial from silt rich spring runoff the elk suffered from two pathological conditions one resulting in fusion of the fourth and fifth cervical vertebrae and the other resulting in exces sive bone tissue on the proximal ends of the first ribs seventh cervical and first and second thoracic vertebrae the marmes elk is larger than modern rocky mountain elk c e nelsoni and is on the large end of the size range of modern roosevelt elk c e roosevelti it is also larger than the similarly aged elk skeleton from three hills alberta a single elk bone from the sentinel gap archaeological site in central washington state dated to about 10 200 14 c years bp and located 130 km west of marmes rockshelter is the same size as the same bone of the marmes elk terminal pleistocene elk in eastern washington likely grew to exceptionally large size as a result of abundant grass at the time forage that de creased in abundance as holocene climatic conditions developed

coal related sources of organic contamination in sediments and water from the bierawka river poland abstract river sediments mixed with coaly material occur all along the length of the bierawka river poland to identify the origin of the coal in the sediment the coaly material was investigated by reflected light microscopy and rock eval pyrolysis and solvent extracts by gas chromatography mass spectrometry gc ms organic compounds dissolved in water were separated by solid phase extraction spe and analyzed by gc ms the results point to a kerogen iii source petrographic analyses confirm abundant coal charred and coked particles in the sediments vitrinite reflectance varied between 0 66 0 80 r r without any large spatial variation the coaly particles have different sources generally the primary origin of coal particles is from coal processing and the dumping the ash with unburned coal particles from a glass factory near the river source later this material was redeposited along the entire river course in addition hard coal processing crushing washing features are visible in larger coal pieces a second source of coaly organic matter is a coal waste dump at szczyglowice where intensive erosion of steep slopes has delivered copious amounts of organic matter into the river the mixing of this organic matter with that from the glass factory is clearly identified on a ternary diagram pah distributions also show differences between sections the coal particle input from the waste dump increased the relative content of naphthalene relative content downstream as in the coal waste 4 5 ring pahs predominate in the sediments the pyrogenic origin of pahs and aromatic compounds such as methylbiphenyls and dibenzofurane in the sediment is indicated by diagnostic pah ratios burned particles were identified petrographically the river water contains only 2 3 ring pahs possibly of industrial origin or leached from coal particles in the river sediments

changes during the holocene in the size of white tailed deer odocoileus virginianus from central illinois abstract white tailed deer odocoileus virginianus from central illinois varied in size during the holocene the record which extends back to 8450 yr b p indicates small deer through the mid holocene until 3650 yr b p after which size increases although influences of winter climate seasonality anthropogenic effects and other ecological factors should not be discounted an intriguing possible cause of the deer size shifts is insolation driven summer climate and its influence on food resources in the holocene small deer size is correlated with high summer insolation and with low winter insolation climatic models indicate that in spite of changes in insolation holocene winters did not vary greatly through time especially in contrast to summers which were dynamic physiological constraints peculiar to o virginianus make critical the quality of summer forage for determining final adult size summer temperature averaged 2 c warmer than present during the middle holocene which increased evaporation and probably reduced the period of availability of high quality forage low in fiber and high in protein consequently less fuel for growth was consumed by mid holocene deer and only small body size was achieved other possible causes e g bergmann s rule seasonality of clinal variation are considered with reference to central illinois deer but at present the most parsimonious explanation appears to be the summer insolation hypothesis

stacked slantwise convective circulations it is well known that classical ana cold fronts tend to be characterized by mesoscale circulations in which upright line convection feeds a layer of concentrated rearward slantwise ascent occasionally however as in the case study presented in this paper two and sometimes more of these mesoscale circulations coexist within the same cold frontal zone the two slantwise circulations described were observed to be stacked one above the other with a vertical wavelength of less than 2 km although it is often suspected that the circulations at ana cold fronts are enhanced by mesoscale processes such as conditional symmetric instability csi or m adjustment it is notoriously difficult to discriminate between these circulations and the larger scale transverse circulation within which they are embedded the occurrence in this study of multiple circulations with small vertical scale helps to distinguish them from the large scale circulation and this has motivated the detailed examination of this case mesoscale circulations of the kind described are difficult to detect numerical weather prediction nwp models even high resolution models do not usually represent them and conventional observations do not show them clearly this study takes advantage of observations from a high resolution microwave doppler radar plus a high resolution analysis of ultra high frequency wind profiler radar data analysed in the context of output from an operational mesoscale nwp model the study defines the mesoscale structure of the event sufficiently carefully to provide a basis for future idealized modelling studies to investigate the possible roles of csi and m adjustment both of which appear to play a part in the maintenance of the circulations

a stable carbon isotope and biological marker study of polish bituminous coals and carbonaceous shales abstract biological marker and carbon isotopic compositions of coals and carbonaceous shales from the upper carboniferous strata of the upper silesian uscb lower silesian lscb and lublin lcb coal basins were determined to assess depositional conditions and sources of the organic matter n alkane sterane and isoprenoid distribution and carbon isotope ratios are consistent with an origin from higher plants in some cases pristane phytane pr ph ratios of carbonaceous shales roof and floor shales are 29 stereoisomers typical but not conclusive of higher plant origin carbonaceous shales exhibit a wider range of sterane composition suggesting local significant input of algal organic matter significant amounts of benzohopanes and gammacerane are present in some coals although benzohopanes are present at least in small amounts in samples from many different environments they have been reported to occur most commonly in marine environments the present study seems to provide the first example where benzohopanes have been reported in significant amounts in terrestrial organic matter gammacerane is abundant in rocks or sediments deposited in carbonate or highly saline marine environments the finding of high gammacerane concentrations in the coals expands the depositional settings in which it has been observed and questions its utility as an independent indicator of hypersaline carbonate environments stable carbon isotope composition of coals and type iii kerogen in carbonaceous shales as well as correlation of stable carbon isotope composition of saturated and aromatic hydrocarbons in carbonaceous shales from both the uscb and the lscb indicate terrigenous origin bitumens are always co genetic with associated coals and kerogens isotopic data reveal that sofer s genetic classification of oils is not applicable to organic matter in coals

the impact of deformation strain on the formation of banded clouds in idealized modelling experiments experiments are performed using an idealized version of an operational forecast model to determine the impact on banded frontal clouds of the strength of deformational forcing low level baroclinicity and model representation of convection line convection is initiated along the front and slantwise bands extend from the top of the line convection elements into the cold air this banding is attributed primarily to m adjustment the cross frontal spreading of the cold pool generated by the line convection leads to further triggering of upright convection in the cold air that feeds into these slantwise bands secondary low level bands form later in the simulations these are attributed to the release of conditional symmetric instability enhanced deformation strain leads to earlier onset of convection and more coherent line convection a stronger cold pool is generated but its speed is reduced relative to that seen in experiments with weaker deformational strain because of inhibition by the strain field enhanced low level baroclinicity leads to the generation of more inertial instability by line convection for a given capping height of convection and consequently greater strength of the slantwise circulations formed by m adjustment these conclusions are based on experiments without a convective parametrization scheme experiments using the standard or a modified scheme for this model demonstrate known problems with the use of this scheme at the awkward 4 km grid length used in these simulations copyright 2008 royal meteorological society

late quaternary diminution and abundance of prehistoric bison bison sp in eastern washington state u s a bison bison spp occurred in eastern washington state during the late quaternary this area is considered to be peripheral to the center of this taxon s natural range bison in the plains east of the rocky mountains the heart of this range underwent diminution during the late quaternary and apparently also did so in other peripheral areas a ratio diagram of measurement data derived from eight zooarchaeological collections of bison remains recovered from eastern washington in combination with the presence of both sexes and all age classes of individuals indicate that local bison may have also undergone diminution there there are however a relative paucity of bison remains during the middle holocene and an apparent 2000 year absence of bison from eastern washington at this time as a result the hypothesis that bison became smaller elsewhere and then immigrated to eastern washington cannot be falsified both the diminution and the fluctuating abundance of bison appear to be responses to forage quality and quantity d 2004 university of washington all rights reserved

oxidatively and thermally altered high volatile bituminous coals in high temperature coal fire zone no 8 of the wuda coalfield north china abstract coal fires have received increasing attention due to their environmental economic and social impacts their significant influence on coal properties is widely documented by geophysical and geochemical methods the present paper demonstrates by means of coal petrological methods significant changes of microstructure optical appearance and optical properties of medium rank bituminous coals affected by an underground coal fire the studied changes are suggested to result from distinct oxidative and thermal alterations induced by a high temperature regime temperatures over 800 c encountered in the coal fire zone no 8 wuda coalfield the investigated coal seam no 9 represents a high volatile a bituminous coal and is dominated by vitrinite followed by inertinite with minor amounts of liptinite the microstructure of the coal fire affected coals facilitate a broad spectrum of characteristic features the microscopic analyses revealed development of 1 non tectonic fissures and non tectonic fractures 2 distinct micropores 3 dark oxidations rims and 4 bright spots interpreted as incipient mesophases optical properties were characterised for megasporinite and vitrinite in the examined megasporinite a noticeable anisotropy and distinct granular appearance was observed in the investigated coals both a dominant increase as well as a minor decrease in both random and maximum vitrinite reflectances were documented for 1 coal grains and 2 dark rimmed vitrinite at non tectonic fissures and non tectonic fractures in addition also a characteristic bimodal vitrinite population was measured the increase in bireflectance was clearly documented for two sub zones within the coal fire zone no 8 the applied kilby s cross plots suggested a large overlapping of the data sets of r max and r min indicating marked changes in vitrinite structure the applied coal petrological approach revealed distinct changes to the coal s microstructure appearance as well as to optical properties induced by the underground coal fire the presented coal petrographic approach may help determine the extent of coal fires in coal mines and the direction of propagation of coal fire front

parcel theory in three dimensions and the calculation of scape slantwise convective available potential energy scape is a measure of the degree to which the atmosphere is unstable to conditional symmetric instability csi it has until now been defined by parcel theory in which the atmosphere is assumed to be nonevolving and balanced that is two dimensional when applying this two dimensional theory to three dimensional evolving flows these assumptions can be interpreted as an implicit assumption that a timescale separation exists between a relatively rapid timescale for slantwise ascent and a slower timescale for the development of the system an approximate extension of parcel theory to three dimensions is derived and it is shown that calculations of scape based on the assumption of relatively rapid slantwise ascent can be qualitatively in error for a case study example of a developing extratropical cyclone scape calculated along trajectories determined without assuming the existence of the timescale separation show large scape values for parcels ascending from the warm sector and along the warm front these parcels ascend into the cloud head within which there is some evidence consistent with the release of csi from observational and model cross sections this region of high scape was not found for calculations along the relatively rapidly ascending trajectories determined by assuming the existence of the timescale separation

the relation of moist symmetric instability and upper level potential vorticity anomalies to the observed evolution of cloud heads the cloud head phenomenon has been known for some time as a precursor of rapid cyclogenesis based upon satellite imagery two stages of cloud head development are identified in this study that can be related to early and late stages of the associated cyclone weakly convex cloud heads emerge from the baroclinic zone at an early stage in cyclogenesis and strongly convex cloud heads develop in association with the rapid deepening of the cyclone trajectories are used to highlight the role of an upper level potential vorticity pv anomaly in the growth of the strongly convex cloud head and the main flow associated with the growth of the strongly convex cloud head is viewed using isentropic analysis the possible role of moist symmetric instability in the development of both weakly and strongly convex cloud heads is discussed and a new diagnostic for measuring the vertically integrated extent of realizable symmetric vrs instability based on the moist geostrophic pv is introduced royal meteorological society 2002 g j shutt s contribution is crown copyright

molecular characterisation of vitrinite in relation to natural hydrogen enrichment and depositional environment the py gc ms results of the study carried out on two groups of vitrinites perhydrous and non perhydrous of diaerent age and properties and on a trimaceralic coal associated with one of the perhydrous group are discussed such a study provides information about the eaect of natural hydrogen enrichment on vitrinite structure at the molecular level moreover the influence of the diaerent conditions in the sedimentary environment on the chemical structure of the vitrinite is also discussed this influence is inferred through diaerences in the distribution and relative amount of phenolic compounds found in the pyrolysates from two samples of two diaerent coal beds in the same basin but formed under diaerent paleoenvironmental conditions for vitrinites with a high h c atomic ratio despite having a strong perhydrous character their pyrolysates exhibit the highly phenolic signature typical of lignin derived material with only minor aliphatic compounds thus the major chemical structural elements in these vitrinites are simple phenols with a high contribution of para alkyl substituted derivatives however there is no parallel relationship between the evolution of the oxygenated functionalities and the reflectance values from the results obtained a coalification pathway where hydrogenation processes predominate over thermal ones is proposed the presence of resin like substances and or oils which are two of the causes of natural hydrogen enrichment in the molecular structure of vitrinites have therefore aaected the normal evolution of the lignin and contributed to the special properties of this type of materials 2000 elsevier science ltd all rights reserved

assessment of hydrocarbon source rock potential of polish bituminous coals and carbonaceous shales abstract we analyzed 40 coal samples and 45 carbonaceous shale samples of varying thermal maturity vitrinite reflectance 0 59 to 4 28 from the upper carboniferous coal bearing strata of the upper silesian lower silesian and lublin basins poland to evaluate their potential for generation and expulsion of gaseous and liquid hydrocarbons we evaluated source rock potential based on rock eval pyrolysis yield elemental composition atomic h c and o c and solvent extraction yields of bitumen an attempt was made to relate maceral composition to these source rock parameters and to composition of the organic matter and likely biological precursors a few carbonaceous shale samples contain sufficient generation potential pyrolysis assay and elemental composition to be considered potential source rocks although the extractable hydrocarbon and bitumen yields are lower than those reported in previous studies for effective type iii source rocks most samples analysed contain insufficient capacity for generation of hydrocarbons to reach thresholds required for expulsion primary migration to occur in view of these findings it is improbable that any of the coals or carbonaceous shales at the sites sampled in our study would be capable of expelling commercial amounts of oil inasmuch as a few samples contained sufficient generation capacity to be considered potential source rocks it is possible that some locations or stratigraphic zones within the coals and shales could have favourable potential but could not be clearly delimited with the number of samples analysed in our study because of their high heteroatomic content and high amount of asphaltenes the bitumens contained in the coals are less capable of generating hydrocarbons even under optimal thermal conditions than their counterpart bitumens in the shales which have a lower heteroatomic content

a numerical study of typhoon megi 2010 part i rapid intensification abstracttyphoon megi 15w was the most powerful and longest lived tropical cyclone tc over the western north pacific during 2010 while it shared many common features of tcs that crossed luzon island in the northern philippines megi experienced unique intensity and structural changes which were reproduced reasonably well in a simulation using the advanced research weather research and forecasting model arw wrf with both dynamical initialization and large scale spectral nudging in this paper processes responsible for the rapid intensification ri of the modeled megi before it made landfall over luzon island were analyzed the results show that megi experienced ri over the warm ocean with high ocean heat content and decreasing environmental vertical shear the onset of ri was triggered by convective bursts cbs which penetrate into the upper troposphere leading to the upper tropospheric warming and the formation of the upper level warm core in turn cbs with their roots inside of the eyewall in

the pristane n heptadecane ratio as an indicator for recognition of hydrocarbon migration effects a simple scheme is proposed for type iii kerogen source rocks which uses pristane n heptadecane concentration ratios for recognition of hydrocarbon expulsion effects within the maturity interval 0 82 1 03 rm this scheme can be applied from gas chromatography data routinely obtained by most petroleum geochemistry studies in exploration exploration of this scheme to oil prone type ii source rocks appears very promising

terminal pleistocene change in mammal communities in southeastern washington state usa abstract small mammal communities in western north america experienced declines in taxonomic richness across the late pleistocene to holocene transition pht a recent natural global warming event one community also experienced a decline in evenness and others replaced one species with a congener variability in response of small mammal communities to pht warming is apparent at the presently arid and xeric marmes site in the columbia basin of southeastern washington state megafauna were absent by about 13 000 cal yr bp evenness of small mammals declined about 11 700 cal yr bp and again about 11 400 cal yr bp whereas richness declined about 11 400 cal bp regional faunal turnover was however minimal among small bodied taxa local mammal communities are depauperate as a result of megafaunal extinctions and subsequent decreases in small mammal richness and evenness the latter chronologically corresponds with a decrease in primary productivity driven by increasing warmth and aridity more faunas must be studied in order to fully document the range of variability in the responses of mammalian communities to pht warming documentation of patterns in those responses will facilitate understanding and enhance predictive accuracy with respect to responses of mammalian communities to modern global warming