multiple charcoal profiles in a scottish lake taphonomy fire ecology human impact and inference abstract sedimentary microscopic charcoal in lacustrine environments has received much attention although this has been concerned largely with the deposition of modern charcoal or with distributions through time based on single profiles lake sediments are dynamic entities however and the phenomenon of sediment focusing for example will lead to the redistribution of pollen spores and charcoal the process may not always result in greatly altered fossil assemblage in percentage terms but values for individual indicators or their absolute values may be affected strongly this is investigated using multiple microscopic charcoal profiles covering many thousands of years from black loch fife eastern scotland relative and absolute measures of charcoal depiction are considered as a prelude to discussion of microscopic charcoal taphonomy in the context of a small lake fire ecology and human impacts the charcoal measures concentrations influx and charcoal to pollen ratios all follow similar patterns though with very different numerical values two cores have charcoal influx values of similar orders of magnitude for much of the holocene whereas quantities in two other cores vary by a factor of 16 after 1000 cal bp the differences between influx measures for total pollen and charcoal indicate that focusing effects between the two indicators are dissimilar correlations with pollen and spore taxa are explored and demonstrate the problems of discrepant data between profiles charcoal pollen patterns for specific cultural periods are examined for one profile and they provide data suggesting that a direct fire vegetation relationship for the site is unproven the need to adopt a multi causal approach to inference is emphasised

the pre quaternary history of fire abstract although evidence for land vegetation comes from the silurian and maybe even earlier the first record of fossil charcoal fusain is from the late devonian for this period there are only one or two isolated records not until the early carboniferous is there a record of extensive charcoal deposits mainly preserved in near shore clastic sediments which provide evidence of significant and widespread wildfires by the late carboniferous charcoal was common or abundant in a wide range of facies including tropical wetland peats wildfire played an important role in shaping the environment at this time the latest palaeozoic and early mesozoic records of charcoal are fewer whereas important deposits of late mesozoic age are found worldwide the occurrence of charcoal at the cretaceous tertiary boundary has been highlighted as evidence for a global fire following a meteorite impact but this interpretation is questionable charcoal has been widely reported from tertiary sediments and its appearance in the quaternary and recent is not solely as a result of human impact through the past 400 million years there have been major changes in atmospheric oxygen levels that affected fire intensity and frequency fire systems thus have a long history and their impact on shaping the environment is assessed

measuring the sea ice floe size distribution sea ice is broken into floes whose diameters range from meters to a hundred kilometers this fragmentation affects the resistance of the ice cover to deformation and the melting at floe sidewalls in summer floes are broken by waves and swell near the ice edge and throughout the pack by isostatic imbalances thermal cracking winds and currents in winter they are welded together by freezing floe size can be measured by several properties p for instance area or mean caliper diameter two definitions of floe size distribution seem useful f p the fraction of area covered by floes no smaller than p and n p the number of floes per unit area no smaller than p f p can be measured by sets other than areas such as the fraction of a line or of a point set covered by floes no smaller than p if n behaves like for small where is mean caliper diameter must be greater than 2 so that the small floes occupy finite area if 2 1 the perimeter of small floes is infinite several summertime distributions have been measured on a log log graph their slopes local values of range from 1 7 to 2 5 one distribution follows a power law the others have steeper slopes for larger floes and more gradual slopes for smaller floes another sampling strategy is to measure the lengths of line segments on floes the distribution of these chord lengths is equivalent to the distribution of floe diameters the variance of an estimate of the fraction g of area covered by floes in any size range is g 1 g k 1 where k is the equivalent number of independent samples k can be found from the autocovariance of the indicator function for the chosen size range for line sampling of a narrow range of floe diameters k is the ratio of the sample length to the floe diameter

macro and micro factors affecting coal seam quality and distribution in southern africa with particular reference to the no 2 seam witbank coalfield south africa abstract petrographical and palynological coal quality investigations relating to variations in one of the best known and well researched coalfields in africa the witbank coalfield and one of the most commercially important seams within this coalfield the no 2 seam are highlighted in this paper the investigations were based on 14 channel samples covering a 40 20 km 2 area in the witbank coalfield the results indicate that the coals in the no 2 seam were formed at the stage of major change over from dwyka to ecca floras as illustrated by the progressive dying out of dwyka pollens and spores and the introduction of ecca floral elements this also suggests a rapid amelioration of climate over the period of peat accumulation following a period of continental glaciation furthermore it is proposed that the in seam horizons reflect fluctuating of cyclic environments probably due to changing water level and plant communities due to changing growth environments saccate pollens appear to occur in association with vitrinite rich microlithotypes trilete spores with inertodetrite and carbominerite rich microlithotypes and plicates with inertite semifusite inertodetrite microlithotypes acritarchs nonspinose are present in parts of the seam where inertodetrite is common and in association with unusual suites of trace and major elements possibly indicating changing geochemical environments in high groundwater conditions petrographic results indicate that the coals are medium rank hypobituminous and show wide variations in maceral mineral and microlithotype compositions both vertically and laterally on the basis of microlithotype and mineral group analyses investigations were undertaken to establish vertical subdivisions by the study of historical patterns and possible lateral correlations of these subdivisions in the area under investigation these methods were then compared with distribution of selected chemical and geochemical parameters the evidence suggests that a common sequence of major events and some minor events occurred during the accumulation of the no 2 seam as manifested by petrographic and palynological facies three major periods or zones are recognized these tepresent periods of relatively stability quiescence separated by major in seam disruptive events namely flood deposits bearing high proportions of detrital organic material or minor clastic sedimentation these zones are subdivided into several subzones representing periods of reworking local flooding or rise in ground water levels and or changing geochemical environments these events can be recognized throughout the area under investigation but the manifestation of these events varies from area to area depending upon topographic situation proximity to river channels valley flanks or palaeoshorelines degree of subsidence and compaction geochemical environment and length of time under a specific set of conditions thus channels in close proximity to one another or in similar positions relative to valley flanks or axes appear to be remarkably similar to one another direct correlation of stratigraphic zones and sub zones from sample site of sample site was therefore possible although the methods to achieve this are complex and require the support of several supplementary complementary interpretative techniques coal quality variations and distribution within the original seam are therefore explicable in terms of the detailed factors listed above

ice floe distribution in the sea of okhotsk in the period when sea ice extent is advancing 1 ice floe distribution in the sea of okhotsk during a cold air outbreak was investigated by analyzing several thousand of sea ice images obtained by the aircraft observation on 18 february in 2000 the effective floe size became small from 10 m to 2 m within the marginal ice zone miz the scaling properties of floe distribution are demonstrated by a cumulative number frequency which follows a power law scaling with an exponent the value of increased from 1 5 within the internal ice zone to 2 1 within the miz which means that relatively small ice floes dominate in the miz the effective width of the miz estimated by a wave attenuation theory agreed with the observed width suggesting that the flexural stress of waves penetrating into the ice is one of the possible mechanisms which cause the difference in the scaling property

wind and wave influences on sea ice floe size and leads in the beaufort and chukchi seas during the summer fall transition 2014 sea ice floe size distribution and lead properties in the beaufort and chukchi seas are studied in the summer fall transition 2014 to examine the impact on the sea ice cover from storms and surface waves floe size distributions are analyzed from medea landsat8 and radarsat 2 imagery with a resolution span of 1 100 m landsat8 imagery is also used to identify the orientation and spacing of leads the study period centers around three large wave events during august september 2014 identified by swift buoys and wavewatch iii model data the range of floe sizes from different resolutions provides the overall distribution across a wide range of ice properties and estimated thickness all cumulative floe size distribution curves show a gradual bending toward shallower slopes for smaller floe sizes the overall slopes in the cumulative floe size distribution curves from landsat8 images are lower than while those from radarsat 2 are similar to previously reported results in the same region and seasonal period the medea floe size distributions appeared to be sensitive to the passage of storms lead orientations regardless of length correlate slightly better with the peak wave direction than with the mean wave direction their correlation with the geostrophic wind is stronger than with the surface wind the spacing between shorter leads correlates well with the local incoming surface wavelengths obtained from the model peak wave frequency the information derived shows promise for a coordinated multisensor study of storm effects in the arctic marginal ice zone

observational facts in revealing a close relation between acoustic gravity waves and midlatitude spread f the main purpose of this paper is to provide observational phenomena which show a close relation between acoustic gravity waves agws and blurred traces of hf doppler shifts this relationship is regarded as observational evidence of a close connection of agws with midlatitude spread f msf analyzed with six years of hf doppler records it is found that the frequency shift traces often become very blurred after local sunset and this kind of echo is reasonably assumed to be caused by ionospheric irregularities namely spread f in most of the cases these blurred echoes follow leading agws generally the periods of agws were in a range of 15 30 mins and the doppler frequency shifts were around or greater than 0 5 hz roughly equivalent to the amplitude of agw about 30 50 m s usually during local night when there were agws with larger amplitudes indicated by a frequency shift up to 0 5 hz and above the blurred echoes followed or overlapped them these phenomena lasted for hours in general then weakened gradually with the wavelike echoes still existing or having ceased of course this is not always the case in a few instances clear wavelike disturbances solely are without accompanying blurred echoes or blurred echoes occurred with only small amplitude waves ahead however it should be stressed that such exceptions were quite few statistics show that 23 5 of the total night time records were with blurred traces and 96 of blurred traces were accompanied with agws in this paper some typical examples are provided for different background such as typhoon volcano eruption and other situations whenever agws appeared these observations can be regarded as evidence of agws having a seeding role in exciting msf

observations on the nature and origin of fusain abstract evidence for a wildfire origin of fusain is examined charcoal produced by natural fires and artificial charring resembles fossil fusain both in physical size and shape and in optical reflectance artificially charred leaves and naturally burnt wood are illustrated using the sem reflectance studies on modern charcoals suggest that much semifusinite may be produced by pyrolysis the ecological implications of a wildfire origin of fusain are discussed and it is concluded that fires have been a feature of terrestrial ecosystems from at least the late devonian

evolution of directional wave spectra in the marginal ice zone a new model tested with legacy data abstractfield experimental data from a 1980s program in the greenland sea investigating the evolution of directional wave spectra in the marginal ice zone are reanalyzed and compared with the predictions of a new phase resolving three dimensional model describing the two dimensional scattering of the waves by the vast number of ice floes that are normally present the model is augmented with a dissipative term to account for the nonconservative processes affecting wave propagation observations reported in the experimental study are used to reproduce the ice conditions and wave forcing during the experiments it is found that scattering alone underestimates the attenuation experienced by the waves during their passage through the ice field with dissipation however the model can replicate the observed attenuation for most frequencies in the swell regime model predictions and observations of directional spreading are in agreement for short to midrange wave periods where the wave field quickly becomes

observed changes in sea ice floe size distribution during early summer in the western weddell sea abstract digital aerial photographs are used to measure the change in floe size distribution over an area of the western weddell sea during the ice station polarstern ispol program the results show a significant increase in the number of small floes and brash ice over a 23 day period from 9 december 2004 to 1 january 2005 this is attributed to a net divergence of the pack ice coupled with ice melt that caused ridges to relax and break into their component parts the net effect is a significant increase in total floe perimeter that is important for lateral melt and primary production near floe edges

size distribution and shape properties of relatively small sea ice floes in the antarctic marginal ice zone in late winter in the marginal sea ice zone miz where relatively small ice floes are dominant the floe size distribution is an important parameter affecting melt processes given the larger cumulative perimeter of multiple small floes compared with a single ice floe of the same area smaller ice floes are therefore subject to increased lateral melt however the available data have been very limited so far analysis of sea ice in the sea of okhotsk revealed that while floe size distribution is basically scale invariant a regime shift occurs at a size of about 40 m in order to extend this preliminary result to the antarctic miz and further examine the controlling factors the first concurrent ice floe size and ice thickness measurements were conducted in the northwestern weddell sea and off wilkes land around 64 s 117 e with a heli borne digital video camera in the late winter of 2006 and 2007 respectively the floe sizes ranged from 2 to 100 m our analysis shows 1 the scale invariance and regime shift are confirmed in both regions 2 the floe size at which regime shift occurs slightly increases from 20 to 40 m with ice thickness consistent with the theory of the flexural failure of sea ice and 3 the aspect ratio is 1 6 1 9 on average close to the previous results based on these results the processes affecting the floe size distribution and the subsequent implications on melt processes are discussed by applying a renormalization group method to interpret the scale invariance in floe size distribution the fractal dimension is related to the fragility of sea ice these results indicate the importance of wave ice interaction in determining the floe size distribution

submesoscale sea ice ocean interactions in marginal ice zones signatures of ocean eddies fronts and filaments are commonly observed within marginal ice zones mizs from satellite images of sea ice concentration and in situ observations via ice tethered profilers or underice gliders however localized and intermittent sea ice heating and advection by ocean eddies are currently not accounted for in climate models and may contribute to their biases and errors in sea ice forecasts here we explore mechanical sea ice interactions with underlying submesoscale ocean turbulence we demonstrate that the release of potential energy stored in meltwater fronts can lead to energetic submesoscale motions along mizs with spatial scales o 10 km and rossby numbers o 1 in low wind conditions cyclonic eddies and filaments efficiently trap the sea ice and advect it over warmer surface ocean waters where it can effectively melt the horizontal eddy diffusivity of sea ice mass and heat across the miz can reach o 200 m 2 s 1 submesoscale ocean variability also induces large vertical velocities order 10 m d 1 that can bring relatively warm subsurface waters into the mixed layer the ocean sea ice heat fluxes are localized over cyclonic eddies and filaments reaching about 100 w m 2 we speculate that these submesoscale driven intermittent fluxes of heat and sea ice can contribute to the seasonal evolution of mizs with the continuing global warming and sea ice thickness reduction in the arctic ocean submesoscale sea ice ocean processes are expected to become increasingly prominent

the record of triassic charcoal and other evidence for palaeo wildfires signal for atmospheric oxygen levels taphonomic biases or lack of fuel abstract as wildfires are today important sources of disturbance in many terrestrial ecosystems it is of great interest to understand how different environmental parameters and fire activity interacted during past periods of the earth history fossil charcoal inertinites and pyrogenic polycyclic aromatic hydrocarbons pahs represent the only direct evidence for the occurrence of such palaeo wildfires in the present study a review of published data together with new data on the occurrence of fossil charcoal for the permian and the triassic is presented for a long time it has been speculated that an assumed lack of evidence for palaeo wildfires during the triassic should be explained by a large drop in atmospheric oxygen concentration following or during the end permian mass extinction event preventing the occurrence of wildfires however evidence for palaeo wildfires is relatively common in many middle and late triassic strata whereas such evidence is almost totally lacking from early triassic sediments the interpretation of this charcoal gap or depression is difficult as many factors e g atmospheric oxygen concentration taphonomical biases lack of sediments suitable for the preservation of macroscopic charcoal lack of fuel and ignorance of scientists may have influenced not only the production but also the preservation and recovery of evidence for palaeo wildfires during this period thus it is not clear whether this early triassic charcoal gap can also be seen as evidence for an assumed wildfire gap or not without any doubt further investigations on the early triassic record of charcoal and other evidence for palaeo wildfires will be necessary before this problem can be solved in fact it can be expected that the number of published records of early triassic evidence for palaeo wildfires will increase in the future as more and more scientist working on sediments of this age may become aware of the interest in fires from this time this will certainly make it possible to give a much better picture of the temporal and regional distribution of wildfires during this period in the future

experiments in waterlogging and sedimentology of charcoal results and implications abstract fossil charcoal has a sporadic occurrence in sedimentary rocks since devonian time it is moderately common as a component of the organic material found in a wide variety of facies but there are also some notable concentrations which occur locally these occurrences have considerable palaeobotanical and palaeoecological value because the process of charring may result in excellent preservation of plant tissue if assemblages of charred material are to be used to interpret palaeoenvironments it is important to understand the behaviour of charcoal during transport from the site of the fire charcoal is an unusual sedimentary material because most fresh material floats but with prolonged immersion becomes waterlogged and sinks we carried out a series of waterlogging experiments on uncharred material and charcoal from a range of different plant types and tissues these show considerable variations in the rates of waterlogging of different charred and uncharred plant tissues and it is suggested that buoyancy contrasts are likely to result in separation during transport and deposition furthermore experiments in a flume tank have shown that the process of deposition of charcoal in sand is controlled by the rate of migration of bedforms which is in turn determined by depth flow velocity and sediment supply allochthonous assemblages of charred and uncharred plant debris will most probably be biased and not fully representative of the contemporaneous plants or vegetation the presence of charcoal concentrations may be used as an aid in interpreting palaeohydraulic conditions

sea ice melting and floe geometry in a simple ice ocean model a coupled sea ice ocean numerical model has been developed that addresses the role of floe geometry during summertime melting the model contains a diagnostic equation for average floe diameter in addition to the usual prognostic equations for ice volume per unit area and ice concentration the partition between melting on the top bottom and lateral side surfaces of floes is examined using time dependent simulations with differing initial average floe diameters the different parameterizations for bottom and lateral melting in the literature are also compared and found to vary significantly the results show that lateral melting is important only for floes with diameters less than o 30 m given atmospheric thermal forcing typical of the central arctic in summer this means that the decrease in ice concentration over the summer is a strong function of floe diameter in keeping with simple geometrical arguments in all cases about 80 of the net thermal energy that enters the ocean through leads goes toward melting ice while the rest warms the ocean

phyterals of humic coals in the u s s r abstract the results of a study of plant remains found in coals of devonian to neogene age which were studied mainly by the method of phyteral analysis are presented most of phyterals discussed and illustrated in this paper are from coal basins in the u s s r however a discussion of occurrences of phyterals in coal basins worldwide is also included middle devonian coals contain fungal remains and phyterals of the enigmatic vascular plant orestovia the most characteristic phyterals of euramerican carboniferous coals are the following periderm of stems and rhizomes of lepidophytes wood and cortex of gymnosperms of uncertain systematic position rachides of pteridosperms and fructifications of spore bearing plants vitrinized phyterals predominate over fusinized phyterals in carboniferous coals in permian coals of gondwana and angarida vitrinized and fusinized woods bark tissues and leaves of pycnoxylic gymnosperms are characteristic phyterals differences in phyteral composition of early and late permian coals indicate that phyterals from vitrinized leaves were more dominant in late permian coals triassic coals rarely contain phyterals of known affinity jurassic and early cretaceous coals are similar in phyteral composition periderm and cork of conifers and ginkgoaceous plants are typical phyterals phyterals of vitrinized and fusinized gymnospermous wood played a significant role in these coals as well leaf phyterals usually compose layers of the paper and fall of leaves coals distinctive characteristics of phyteral composition of cenozoic coals are 1 wide distribution of lignitized woods 2 constant presence of well identified and very specific root remains 3 high content of plant attritus 4 commonly occurring and distinctive fungal phyterals further study of coal phyterals is suggested for correlation of coal seams and coal bearing strata and for the prediction of coal quality

the effect of a storm on the 1992 summer sea ice cover of the beaufort chukchi and east siberian seas for the summer beaufort chukchi and east siberian seas a variety of active and passive microwave satellite data are used to determine the response of the ice edge and interior to a storm specifically the study concentrates on a low pressure system that passed over the region between august 14 and 20 1992 with peak geostrophic winds of about 18 m s 1 through the use of the ers 1 imaging radar and the special sensor microwave imager the ice response is examined at two locations at the ice edge for a nearly stationary location in the chukchi sea and in the ice interior along three swaths in the beaufort chukchi and east siberian seas the ice edge observations show that the storm fractures the large floes into small floes some of which are advected into the adjacent warm water the ice interior observations show that the storm caused an increase in the open water amount and a shift in the floe size distribution toward smaller floes in the ice interior application of the cumulative number distribution n d where n is the number of floes per unit area that are no smaller than some floe diameter d shows that for d 1 km n behaves like d where lies in the range 1 8 2 9 our analysis also shows that this slope is not affected by the storm and is slightly larger near the ice edge

temperate rainforests near the south pole during peak cretaceous warmth the mid cretaceous period was one of the warmest intervals of the past 140 million years1 5 driven by atmospheric carbon dioxide levels of around 1 000 parts per million by volume6 in the near absence of proximal geological records from south of the antarctic circle it is disputed whether polar ice could exist under such environmental conditions here we use a sedimentary sequence recovered from the west antarctic shelf the southernmost cretaceous record reported so far and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82 s during the turonian santonian age 92 to 83 million years ago this record contains an intact 3 metre long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores a climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1 120 1 680 parts per million by volume and a vegetated land surface without major antarctic glaciation highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide multi proxy core data and model simulations support the presence of temperate rainforests near the south pole during mid cretaceous warmth indicating very high co2 levels and the absence of antarctic ice

implications of fractured arctic perennial ice cover on thermodynamic and dynamic sea ice processes decline of the arctic summer minimum sea ice extent is characterized by large expanses of open water in the siberian laptev chukchi and beaufort seas and introduces large fetch distances in the arctic ocean long waves can propagate deep into the pack ice thereby causing flexural swell and failure of the sea ice this process shifts the floe size diameter distribution smaller increases floe surface area and thereby affects sea ice dynamic and thermodynamic processes the results of radarsat 2 imagery analysis show that a flexural fracture event which occurred in the beaufort sea region on 6 september 2009 affected 40 000 km2 open water fractional area in the area affected initially decreased from 3 7 to 2 7 but later increased to 20 following wind forced divergence of the ice pack energy available for lateral melting was assessed by estimating the change in energy entrainment from longwave and shortwave radiation in the mixed layer of the ocean following flexural fracture 11 54 mj m 2 of additional energy for lateral melting of ice floes was identified in affected areas the impact of this process in future arctic sea ice melt seasons was assessed using estimations of earlier occurrences of fracture during the melt season and is discussed in context with ocean heat fluxes atmospheric mixing of the ocean mixed layer and declining sea ice cover we conclude that this process is an important positive feedback to arctic sea ice loss and timing of initiation is critical in how it affects sea ice thermodynamic and dynamic processes

power scaling and seasonal changes of floe areas in the arctic east siberian sea the cumulative number versus floe area distribution of seasonal sea floes from six satellite images of the arctic ocean during the summer breakup and melting is fit by two scale invariant power law scaling regimes for floe areas ranging from 30 to 28 400 000 m2 scaling exponents for larger floe areas range from 0 6 to 1 0 with an average of 0 8 scaling exponents for smaller floe areas range from 0 3 to 0 6 with an average of 0 5 the inflection point between the two scaling regimes ranges from 283 102 to 4850 102 m2 and generally moves from larger to smaller floe areas through the summer melting season the stability of the power scaling results is demonstrated for two of the images by dividing each in half and analyzing each half separately with the result that the scaling exponents and the size of the inflection points are nearly the same for each half as for the whole image we propose that the two scaling regimes and the inflection between them are established during the initial breakup of sea ice solely by the process of fracture the distributions of floe size regimes retain their scaling exponents as the floe pack evolves from larger to smaller floe areas from the initial breakup through the summer season due to grinding crushing fracture and melting the scaling exponents for floe area distribution are in the same range as those reported in previous studies of arctic floes and for the single scaling exponents found for crushed and ground geologic materials including streambed gravel lunar debris and artificially crushed quartz the single scaling exponent found for fault gouge falls below the range for floes possibly because the fracturing and grinding process in fault gouge takes place under high confining pressure a probabilistic model of fragmentation is proposed that generates a single power law scaling distribution of fragment size

characteristics of sea ice floe size distribution in the seasonal ice zone 1 the size distribution of sea ice floes was observed by coordinated landsat imagery and video monitoring conducted from an icebreaker and a helicopter for an area 38 km 26 km in seasonal sea ice in the southern sea of okhotsk in february 2003 the combination of imagery on several scales allowed measurements of ice floes over three orders of magnitude from 1 m to 1 5 km two different regimes were observed floes larger than about 40 m have a power law number density with an exponent of 1 87 in the lower range of earlier results below 40 m the power law exponent is 1 15 the cause of these two different regimes is hypothesized to lie in the effects of swell on floes of different sizes and thicknesses the importance of the floe size distribution for lateral melting is elucidated

charcoal recognition taphonomy and uses in palaeoenvironmental analysis abstract charcoal predominantly the product of wildfires is abundant in many sedimentary rocks deposited in a wide range of environments from terrestrial to marine it also occurs in some volcanic rocks this paper outlines aspects of charcoal formation both natural and experimental and briefly considers the taphonomic processes leading to a final assemblage this is done using examples from recent fires and through experimentation the ways in which charcoal assemblages are recognized in the field and extraction in the laboratory are also considered methods of charcoal identification are presented the range of charcoalified plant organs that can be found is discussed and a wide range of study methods outlined including light microscopy dark field light microscopy reflectance microscopy scanning electron microscopy and synchrotron radiation x ray tomographic microscopy emphasis in this paper is on the study of macro and meso charcoal above180 m finally there is a consideration of the broad use of charcoal from plant evolution studies fire history studies vegetation studies anatomical studies climate and atmospheric studies and the wider importance of charcoal for the earth and biological sciences charcoal is information rich but yet is an under utilized resource

morphological features of ionospheric response to typhoon couplings between the ionosphere and meteorological events have been studied widely however most of them are individual case studies or correlation analyses and few are aiming at the full morphological features of the ionospheric response processes in this paper complete records of 24 strong typhoons from 1987 to 1992 were collected and comparison was made with corresponding ionospheric hf doppler shift data the main purpose of the present work is to find the temporal evolution of these responses and their common features by the merit of the continuities of hf doppler shift observation in time on the basis of the statistical analyses this paper reveals the common features of ionospheric responses to typhoon a summary of these characteristics is as follows 1 during the existing time of a typhoon there are almost always medium scale traveling ionospheric disturbances tids in the ionosphere especially when a strong typhoon is landing or near the coast of a mainland 2 these tids show quite clear periodicity and their periods vary with time and gradually grow longer 3 after sunset the wavelike disturbances with large magnitudes often excite the midlatitude spread f 4 the intense typhoon can cause the wavelike records of the doppler shift to show the s shaped echo tracing which means that the amplitudes of those waves are sufficiently large and 5 the sunrise like phenomena often appear in nonsunrise time during the period the typhoon exists the phenomena mentioned above are generally in agreement with the linear propagation theories of the acoustic gravity waves agws in the atmosphere a typhoon is surely one of the important ground sources of the wavelike disturbances in troposphere this source is very effective especially when a typhoon is landing on or near a mainland coast of course the morphological details of the ionospheric response to typhoon can by no means be completely identical every time in this study except for tids that almost always appear during all the typhoon events the other common features are not seen every time however we are certain that the phenomena summarized above are statistically the manifestation of the ionospheric response to typhoon since they appear much more frequently during periods influenced by typhoon

the response of ice floes to ocean waves a precise linear mathematical theory is reported to model the response of a solitary ice floe in ocean waves allowing the floe to bend with the passing wave both infinite and finite water depths are considered and the model is also extended to include a pair of separated floes of different length the case of n floes then being a natural and straightforward development for a single ice floe perfect transmission is achieved whenever the wavelength beneath the ice couples perfectly to the length of the ice floe then the strains induced in the bending ice floe reach a maximum and because multiple cycle tuning can occur in floes which are long compared to the wavelength strain response amplitude operators raos are complicated by considering the case of infinite stiffness heave and roll raos are also found for typical ocean wave periods and these agree well with two dimensional rigid body models finally ice floes of different diameters but constant 1 m thickness are subjected to spectral forcing and the strain spectral density for each is found spectral density envelopes increase gradually with floe diameter achieving a maximum value for a floe of about 102m thereafter strains never decrease below those for the 80 m curve owing to multiple cycle tuning this may explain the presence of zones within an ice field where floe size never exceeds some prescribed value results obtained from the complete theory for two adjacent floes do not differ significantly from those found by applying the single floe model serially except when the separation is very small

petrology depositional environment and utilization potential of late paleocene coals from the obed marsh deposit west central alberta canada abstract the obed marsh coal deposit is of late paleocene age and contains over 200 million tons of subbituminous b to high volatile bituminous c coal petrographic analysis of three sections from seams 1 and 2 reveals high amounts of huminite and relatively low amounts of liptinite and inertinite with the exception of some intervals in both seems the persistent high ratio of huminite to liptinite and inertinite indicates a relatively reducing environment a feature also expressed by the relatively low inertinite content examination of the in seam profiles also indicates undisturbed peat accumulation over long periods of time the obed coals similar in rank and composition to the hat creek coals of british columbia formed in a freshwater environment and can be used as feedstock for combustion gasification furthermore the intervals rich in liptinite and petroleum like substances may be utilized for liquefaction hydrogenation

characterization of ikaite caco3 6h2o crystals in first year arctic sea ice north of svalbard we identified ikaite crystals caco3 6h2o and examined their shape and size distribution in first year arctic pack ice overlying snow and slush layers during the spring melt onset north of svalbard additional measurements of total alkalinity ta were made for melted snow and sea ice samples ikaite crystals were mainly found in the bottom of the snowpack in slush and the surface layers of the sea ice where the temperature was generally lower and salinity higher than in the ice below image analysis showed that ikaite crystals were characterized by a roughly elliptical shape and a maximum caliper diameter of 201 0 115 9 m m n 918 since the ice melting season had already started ikaite crystals may already have begun to dissolve which might explain the lack of a relationship between ikaite crystal size and sea ice parameters temperature salinity and thickness of snow and ice comparisons of salinity and ta profiles for melted ice samples suggest that the precipitation dissolution of ikaite crystals occurred at the top of the sea ice and the bottom of the snowpack during ice formation melting processes

declassified high resolution visible imagery for arctic sea ice investigations an overview abstract since 2009 subsets of declassified satellite images of arctic sea ice have been released as literal image derived products lidps with one meter resolution for scientific use the collections include imagery acquired over six fixed locations in the arctic basin since 1999 targeted acquisitions over drifting ice parcels from 2009 on provide an added dimension to the lidp archive this mode of acquisition is especially useful for capturing time varying processes during the melt season in this paper we describe the characteristics of lidps the extent of the current archive and highlight their uses for arctic sea ice science at this writing the archive of lidps is still quite limited and thus this paper illustrates the potential utility of the imagery we provide an overview of the retrieval of five sea ice parameters that would benefit significantly from the surface details afforded by the higher resolution lidps they include melt pond coverage open water fraction ridge height floe size and openings and closings two other uses are suggested measurement of lateral melt and the interpretation of radar backscatter the intent is to motivate geophysical uses of the lidp and future acquisitions results here suggest that the effective observations of sea ice parameters and especially their changes require more focused sampling strategies to address specific spatial and temporal sampling needs presently acquisitions of this type of imagery at fixed locations and drifting sites are being continued and lidps are added to the archive as they are released

fire across the k t boundary initial results from the sugarite coal new mexico usa abstract it has been hypothesized that major global fires occurred following a bolide impact at the cretaceous tertiary boundary evidence for this has been mainly from soot or black carbon at a number of marine boundary sites as well as the occurrence of inertinites fusinite in coals above the boundary in addition the occurrence of fossil charcoal inertinites in potential tsunami deposits has been used to strengthen this idea however fire is known to have been widespread throughout the cretaceous based on the distribution of fossil charcoal and it is necessary to evaluate the claims for a global fire at the k t boundary within the context of this more extensive record of ancient fires the occurrence of the k t boundary within the sugarite coal sequence in the raton basin new mexico offers the opportunity to assess the incidence of fire in local peat forming vegetation in the latest cretaceous across the cretaceous tertiary boundary interval and in the earliest tertiary the distribution of fire products i e fossil charcoal is assessed using a combination of inertinite group macerals in polished blocks of coal and plant particles released by chemical maceration of coal inertinite group macerals fusinite semifusinite inertodetrinite which represent fossil charcoal and particles of charcoal in maceration residues are abundant throughout the sugarite coal sequence both before during and after the k t boundary event samples from below the boundary yield inertinites that constitute more than 20 of the coal three horizons are inertinite rich 50 fire was obviously an important element of the terrestrial environment during the latest cretaceous high inertinite values and abundant charcoal particles characterize the latest cretaceous part of the coal the carbonaceous shale just below the boundary the boundary interval itself and tertiary coals and carbonaceous shales above the boundary charcoal in mineral rich units of the latest cretaceous immediately below the boundary in the boundary interval and in the tertiary is dominated by small inertodetrinite particles these might have been wind blown from regional fires or they may reflect reworking during erosion which led to sediment input into the mire in either case the charcoal signature in these units is the same irrespective of their position in the sequence our data combined with that from two other sites in terrestrial sequences in north america show that fires were an integral part of mire ecosystems through the latest cretaceous and into the early tertiary therefore evidence for distinctive global wildfires at the cretaceous tertiary boundary would have to be sought from careful consideration of other aspects of charcoal deposition including flux rates for charcoal and soot

phanerozoic concentrations of atmospheric oxygen reconstructed from sedimentary charcoal varying concentrations of atmospheric oxygen have affected the development of animals and the role of wildfire in ecosystems reconstructions of past oxygen concentrations from fossil charcoal constrain atmospheric oxygenation over the past 400 million years variations of the earth s atmospheric oxygen concentration po2 are thought to be closely tied to the evolution of life with strong feedbacks between uni and multicellular life and oxygen1 2 on the geologic timescale po2 is regulated by the burial of organic carbon and sulphur as well as by weathering3 reconstructions of atmospheric o2 for the past 400 million years have therefore been based on geochemical models of carbon and sulphur cycling4 5 6 however these reconstructions vary widely4 5 6 7 8 9 10 particularly for the mesozoic and early cenozoic eras here we show that the abundance of charcoal in mire settings is controlled by po2 and use this proxy to reconstruct the concentration of atmospheric oxygen for the past 400 million years we estimate that po2 was continuously above 26 during the carboniferous and permian periods and that it declined abruptly around the time of the permian triassic mass extinction during the triassic and jurassic periods po2 fluctuated cyclically with amplitudes up to 10 and a frequency of 20 30 million years atmospheric oxygen concentrations have declined steadily from the middle of the cretaceous period to present day values of about 21 we conclude however that variation in po2 was not the main driver of the loss of faunal diversity during the permo triassic and triassic jurassic mass extinction events

turbulent upwelling of the mid latitude ionosphere 1 observational results by the mu radar in this paper we present the detailed results of a series of experiments designed to study the coherent backscatter of 50 mhz radar waves from the mid latitude f region data were obtained with the active phased array mu radar in japan and include some auxiliary e region coherent echoes as well as in other turbulent ionospheric phenomena the intense nonthermal scatter comes from irregularities oriented parallel to b the strongest echoes correspond to irregularities at least 20 db stronger than thermal backscatter at the same frequency from typical f region densities at the same range simultaneous observations with ionosondes show that these echoes occur during strong mid latitude spread f as defined by ionosondes the latter phenomenon is certainly much more widespread than the turbulent upwelling events described here but we believe that in some sense these correspond to the most violent mid latitude spread f the strongest echoes occur in large patches which display away doppler shifts corresponding to irregularity motion upward and northward from the radar at the edges of these patches there is often a brief period of toward doppler before the echoing region ceases on rare occasions comparable patches of strong away and toward doppler are detected although in such cases the doppler width of the toward echoes is much narrower than that of the away echoes the away patches often are characterized by mean velocities well over 250 m s and doppler widths full width at half maximum of 50 m s the multiple beam capability at mu allowed us to track the patches in the zonal direction on two days the patches moved east to west in both cases at velocities of 125 m s and 185 m s respectively there is a distinct tendency for the bottom contour of the scattering region to be modulated at the same period as the patch occurrence frequency as well as at higher frequencies this higher frequency component may correspond to substructures in the large patches and to the e region coherent scatter patches which were detected simultaneously in several multiple beam experiments in the companion paper kelley and fukao this issue we explore a number of possible explanations for this phenomenon in more detail

a record of fire vegetation and climate through the last three glacial cycles from lombok ridge core g6 4 eastern indian ocean indonesia abstract charcoal elemental carbon and clastic particle analyses have been undertaken on tropical marine core g6 4 collected from the eastern indian ocean between the lesser sunda islands of indonesia and northwestern australia to help interpret an existing pollen record in addition a new oxygen isotope record has been constructed and several radiocarbon dates produced to allow a refinement of the chronology of the core the record covers the last 300 000 years with three clear glacial interglacial cycles however the new oxygen isotope record and radiocarbon dates suggest a hiatus and it appears that most isotope stage 3 is missing interglacials are characterised by higher values of mangrove fern and rainforest pollen indicating wetter conditions than intervening glacials which have higher cyperaceae and chenopodiaceae values gramineae percentages are also generally higher during glacials but there is a sustained increase in grasses relative to eucalyptus about 185 000 years ago originally interpreted as a change to drier conditions an increase in burning from about 200 000 years ago from charcoal evidence suggests that fire may have been an important contributing factor this and subsequent increases in charcoal may reflect anthropogenic burning and are considered in relation to archaeological evidence for possible times of arrival of people within australia the elemental carbon record shows major differences to that from charcoal and further research is needed to interpret its meaning little consistent evidence for changes in climate or vegetation disturbance is provided by clastic particle influx which may well reveal a record of volcanicity within the region

the partition of air ice ocean momentum exchange as a function of ice concentration floe size and draft a coupled sea ice ocean model is used to examine the relative magnitudes of terms in the sea ice momentum equation for ice concentrations less than 100 this numerical model for steady state horizontally homogeneous flow includes two terms that have previously been neglected in such quantitative models these are oceanic form drag and wave radiation pressure both of which are lateral forces that act on the sides of floes the former is generally decelerative while the latter is accelerative the model accepts as input variables average ice draft areal concentration and floe diameter it is found that form drag can be greater than or of the same order as skin friction drag for small thick floes at low concentrations an exception to this rule occurs when the effect of wakes between floes reduces the local form drag the higher net drag that generally exists at low concentrations implies lower ice floe speeds wave radiation pressure is negligible in all cases although this is sensitive to our choice of fetch parameterization ocean drag is often parameterized in numerical models of sea ice as a skin friction term alone with a constant drag coefficient between ice and prescribed geostrophic current velocities results from the present model are plotted in terms of such a drag coefficient which is a function of concentration floe size and draft this could be useful in future work where floe size data become regularly available for instance from radar satellite imagery

observations of the summer breakup of an arctic sea ice cover the arctic sea ice cover evolves dramatically through the summer melt season floe size distribution fsd is a critical parameter used to examine this change as the ice cover transitions from large rectilinear plates in spring to an ensemble of discrete rounded floes by midsummer the fsd at a given time impacts the dynamic and thermodynamic behavior of the ice cover focusing on the seasonal marginal ice zone in the beaufort and chukchi seas from may to september 2014 we present qualitative and quantitative results derived from national technical means high resolution imagery and supported by ice mass balance buoy data results indicate that as melt accelerates floe breaking pattern and therefore fsd is heavily influenced by the distribution of melt ponds discrete element model results using morphological conditions derived from analyzed satellite imagery confirmed that breaking occurs along ponds and perpendicular to applied stress

image processing for identification of sea ice floes and the floe size distributions an unmanned aerial vehicle was used as a mobile sensor platform to collect sea ice features at ny alesund in early may 2011 and several image processing algorithms have been applied to samples of sea ice images to extract useful information about sea ice the sea ice statistics given by the floe size distribution being an important parameter for climate and wave and structure ice analysis is challenging to calculate due to difficulties in ice floe identification particularly the separation of seemingly connected ice floes in this paper the gradient vector flow gvf snake algorithm is applied to solve this problem to evolve the gvf snake algorithm automatically an initialization based on the distance transform is proposed to detect individual ice floes and the morphological cleaning is afterward applied to smoothen the shape of each identified ice floe based on the identification result the image is separated into four different layers ice floes brash pieces slush and water this makes it further possible to present a color map of the ice floes and brash pieces based on sizes and the corresponding ice floe size distribution histogram the proposed algorithm yields an acceptable identification result and its effectiveness is demonstrated in a case study a discussion on the methods and results concludes the paper

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

multi instrument observation on co seismic ionospheric effects after great tohoku earthquake in this paper evidence of quake excited infrasonic waves is provided first by a multi instrument observation of japan s tohoku earthquake the observations of co seismic infrasonic waves are as follows 1 effects of surface oscillations are observed by local infrasonic detector and it seems these effects are due to surface oscillation excited infrasonic waves instead of direct influence of seismic vibration on the detector 2 these local excited infrasonic waves propagate upwards and correspond to ionospheric disturbances observed by doppler shift measurements and gps tec 3 interactions between electron density variation and currents in the ionosphere caused by infrasonic waves manifest as disturbances in the geomagnetic field observed via surface magnetogram 4 within 4 hours after this strong earthquake disturbances in the ionosphere related to arrivals of rayleigh waves were observed by doppler shift sounding three times over two of the arrivals were from epicenter along the minor arc of the great circle with the second arrival due to a rayleigh wave propagating completely around the planet and the other one from the opposite direction all of these seismo ionospheric effects observed by hf doppler shift appear after local arrivals of surface rayleigh waves with a time delay of 8 10 min this is the time required for infrasonic wave to propagate upwards to the ionosphere

multiyear sea ice floe distribution in the canadian arctic ocean a series of aerial photographic flights made over the polar pack ice during april 1982 from m clure strait in the south to ellef ringnes island in the north shows the changes in ice floe type size and area as the pack moves southwest under the effect of the polar gyre the area has some of the most heavily ridged and dynamically active ice in the arctic ocean floe size distributions were found to fit a negative power relationship y a xb where b 3 7 rather than the expected negative exponential function a prony analysis suggests that a single physical parameter controls the distribution most likely splitting rather than bending shear or crushing the effect of proximity to the coast was investigated and showed that nearshore floes were about 20 smaller than their offshore counterparts the ratio of maximum to minimum floe diameter was consistently 1 5 1 6 the mean floe diameter was found to be 700 m the mean area was 0 38 km 2 heavily hummocked and ridged floes were found to be a fairly constant fraction 1 of the multiyear pack

turbulent upwelling of the mid latitude ionosphere 2 theoretical framework in a companion paper data from the mu radar have been presented which show that during sunspot minimum conditions in japan the mid latitude ionosphere is sometimes characterized by regions of rapid and turbulent upwelling in this paper we explore possible mechanisms for these events the most likely process seems to be the instability of the equilibrium which occurs when the mid latitude plasma is supported against gravity either by an eastward electric field component or by a southward neutral wind as was proposed by perkins 1973 we show for example that the growth rate determined by perkins is considerably higher in sunspot minimum conditions than at sunspot maximum for comparable altitudes of the ionospheric f layer the growth rate is not very large however and we argue here that the observed structures must evolve from preexisting undulations of the bottomside of the f region which are generated by gravity waves that is the gravity waves create finite amplitude structures which are amplified by the plasma instability an intriguing feature of the gravity wave role in this process is that the echoing patches detected by the mu radar and the height bands detected by the arecibo radar which we believe to be related phenomena all seem to propagate to the west this is the same direction reported for the angle of arrival measurements of classic mid latitude spread f by a number of researchers using ionosonde techniques since the mu radar detects the upwelling regions from nonthermal 3 m irregularities there must be mechanism to create such tracers we propose that secondary structures are created at intermediate scales via the e b instability operating on the dome of the upwelling structure and by the neutral wind driven process on either the west or the east wall of the structure depending on the direction of the zonal wind the 3 m waves are then created in a cascade process which brings energy into a range of k space in which the structures are linearly damped finally we discuss the fine structure of the echoing patches and suggest several plausible mechanisms two of which involve e region coupling and one which deals with the vertical structure of the gravity wave seeding process

mesoscale field aligned irregularity structures fais of airglow associated with medium scale traveling ionospheric disturbances mstids in this paper we report the evolution generation amplification and dissipation of optically observed mesoscale field aligned irregularity structures fais similar to 150 km associated with a medium scale traveling ionospheric disturbance mstid event there have not been observations of mesoscale fais of airglow before the mesoscale fais were generated in an airglow depleted front of southwestward propagating mstids that were simultaneously observed by an all sky imager a gps monitor and a digisonde around xinglong 40 4 degrees n 30 5 degrees magnetic latitude china on 17 18 february 2012 a normalized cross correlation method has been used to obtain the velocities of mesoscale fais and mstids the mesoscale fais had an obvious northwestward relative velocity to main body mstids about 87 0 m s on average the direction of this relative velocity was roughly parallel to the depleted fronts furthermore the evolution of the mesoscale fais was mostly controlled by the intensity of the depleted fronts occurred in a highly elevated ionosphere that had a total electron content depletion associated with large negative airglow perturbations 25 the mesoscale fais grew rapidly when they experienced southeastward wind which had a speed of about 100 m s and were measured by a fabry perot interferometer a northeastward polarization electric field within a depleted airglow front can play a controlling role in the development of the mesoscale fais the electric field can significantly elevate the ionosphere and move the mesoscale fais northwestward by the e x b drift the processes for the generation and development of the polarization electric field and the mesoscale fais however need further study

analytical variation in australian coals related to coal type and rank analyses of australian coals ranging in age from permian to miocene are reviewed principally by using the van krevelen diagram atomic o c vs h c but also by plotting calorific value vs volatile matter groups of coals of particular ages or from particular areas or seams within coalfields plot in well defined parts of the diagrams each group however covers only part of the rank range from lignite to semi anthracite accordingly the new zealand nz coal band based on medium to high h c late cretaceous and cenozoic coals is used as a reference maturation path the extremes of h c in low rank australian coals are shown by the particularly high h c jurassic queensland coals and the low h c triassic queensland callide coals the majority of coals plot between these extremes these include cenozoic victorian lignites brown coals which except for high h c pale and light lithotypes are similar to new zealand lignites vitrains from australian permian coals plot across the width of the nz coal band and the range of permian coals extends into much lower h c parts of the van krevelen diagram the spectrum of all coals is continuous throughout the extensive range of h c comparison with data on maceral group compositions shows close relations between h c ratios and the proportion of vitrinite provided allowance is made for the counteracting effects of high h c liptinite and low h c inertinite in most coals vitrinite is the dominant maceral group and the range of h c ratios of vitrain samples from permian coals shows that vitrinite composition also must be significant in influencing the elemental composition of the heterogenous coal

ionospheric and geomagnetic disturbances caused by the 2008 wenchuan earthquake a revisit previous works have shown that coseismic ionospheric disturbances cids after the tsunamigenic 2011 tohoku earthquake tohoku eq mw9 1 covered a vast area and were observed thousands of kilometers away from the epicenter for the purpose of making a comprehensive comparison between powerful oceanic and inland eqs we conduct a retrospective investigation of cids and geomagnetic responses to the 2008 wenchuan eq mw7 9 using a combination of techniques total electron content hf doppler and ground magnetometer it is the very first study to present cids recorded by different techniques at co located sites and profiled with regard to changes of both ionospheric plasma and current geomagnetic field simultaneously the integrated observation also shows that 1 in the wenchuan case most of the ionospheric and geomagnetic disturbances were observed within 1000 km distance which is far less than the tohoku case 2 two groups of cids were found with maximum amplitudes in the direction of azimuth 150 and 135 respectively and 3 the geomagnetic changes were only registered by three magnetometers located to the east and southeast of the epicenter all the facts indicate that the main directional lobe of wenchuan eq energy propagation is to southeast and perpendicular to the direction of the fault rupture but this kind of directivity is not that distinct in the tohoku case we suggest that the different fault slip inland or submarine affecting the way of couplings of lithosphere with atmosphere may contribute to the discrepancies between the two events

coherent and incoherent scatter radar observations during intense mid latitude spread f an intense mid latitude spread f event occurred over puerto rico during the night of february 17 1998 simultaneous observations were made with the cornell university portable radar interferometer cupri located near isabela pr the university of illinois vhf radar located at salinas pr gps receivers at isabela and st croix measuring total electron content the arecibo incoherent scatter radar and the cornell all sky imager located at the arecibo observatory this was the first time that such a broad range of complementary instrumentation captured a mid latitude spread f space weather event it was the first and still only time that a spread f event over the caribbean exhibited large doppler shifts in the vhf spectra this event was characterized with multiple filaments that initially produced receding doppler velocities exceeding 300 m s as seen by cupri and the illinois radar the arecibo incoherent scatter radar recorded line of sight velocities exceeding 100 m s that moved the f layer peak to over 400 km altitude airglow images of 630 0 nm emissions from f region heights showed depleted structures oriented southeast to northwest the large velocities observed with the radars suggest that we caught this event in a stage of explosive development it is interesting that the first fully documented caribbean event occurred during a magnetically active period

fires at the k t boundary carbon at the sumbar turkmenia site abstract we have measured carbon at the marine k t boundary site sm 4 at the sumbar river in turkmenia ussr which has an undisturbed ir profile and the largest known ir anomaly 580 ng cm 2 twenty samples ranging from 100 to 100 cm were analyzed to determine the concentration and 13 c of elemental carbon and kerogen using a cr 2 o 7 oxidation method wolbach and anders 1989 to resolve these components the samples were unusually complex containing 3 kerogen components of distinctive ir spectra and half lives in cr 2 o 7 200 100 and 60 h in addition to soot and charcoal from the k t fire the elemental c has 13 c 25 96 0 6 l o close to the mean for 11 k t sites 25 8 0 6 11 mg cm 2 the first of the 2 kerogen components 13 c 22 8 which dominates in the cretaceous appears to come from detrital carbonaceous shale the second 13 c 27 7 o occurs only in the boundary clay and may come from land plant material swept to sea or phytoplankton grown in the presence of excess light co 2 from fires on land the great thickness of the boundary clay 10 5 cm permits determination of the compositional profiles with unprecedented spatial resolution ir and shocked quartz both representing impact ejecta rise sharply at the boundary peak in the basal layer and then decline soot and total elemental c show a similar spike in the basal layer but then rise rather than fall peaking at 7 cm apparently fires started before the basal layer had settled implying that ignition and spreading of major fires became possible if not immediately then very soon after the impact there is no basis for claims by hansen et al 1987 that k t carbon black first occurs 3 5 m below the danish k t boundary and has 13 c of 27 4 to 27 8 o reexamination of a sample from nye klov shows that these authors confused kerogen with carbon black

a new model for atmospheric oxygen over phanerozoic time a mathematical model has been constructed that enables calculation of the level of atmospheric o2 over the past 570 my from rates of burial and weathering of organic carbon c and pyrite sulfur s burial rates as a function of time are calculated from an assumed constant worldwide clastic sedimentation rate and the relative abundance and c and s contents of the three rock types marine sandstones and shales coal basin sediments and other non marine clastics red beds arkoses by our model values of o2 versus time using a constant total sedimentation rate agree with those for variable sedimentation derived from present day rock abundances and estimates of erosional losses since deposition this agreement is the result of our reliance on the idea that any increase in total worldwide sediment burial with consequently faster burial of c and s and greater o2 production must be accompanied by a corresponding increase in erosion and increased exposure of c and s on the continents to o2 consumption via weathering it is the redistribution of sediment between the three different rock types and not total sedimentation rate that is important in o2 control to add stability to the system negative feedback against excessive o2 fluctuation was provided in the modeling by the geologically reasonable assignment of higher weathering rates to younger rocks resulting in rapid recycling of c and s we did not use direct o2 negative feedback on either weathering of c and s or burial of c because weathering rates are assumed to be limited by uplift and erosion and the burial rate of c limited by the rate of sediment deposition the latter assumption is the result of modern sediment studies which show that marine organic matter burial occurs mainly in oxygenated shallow water and is limited by the rate of supply of nutrients to the oceans by rivers results of the modeling indicate that atmospheric o2 probably has varied appreciably over phanerozoic time during the late carboniferous and permian periods o2 was higher than previously because of the rise of vascular land plants and the widespread burial of organic matter in vast coal swamps a large decrease in o2 during the late permian was due probably to the drying up of the coal swamps and deposition of a large proportion of total sediment in c and s free continental red beds sensitivity study shows that major parameters affecting results are the mean c concentration in coal basins and the relative sizes of the reservoirs of young rapidly recycled versus old rocks less sensitivity was found for changes over time in total land area undergoing weathering and the use of direct o2 negative feedback on marine carbon burial good agreement for rates of c burial calculated via our model and via independent models which are based on the use of stable carbon isotopes indicates that the dominant factor that has brought about changes in atmospheric o2 level and the isotopic composition of dissolved inorganic carbon in seawater over phanerozoic time is sedimentation and not weathering or higher temperature phenomena such as basalt seawater reaction

delineation of the distinctive nature of tertiary coal beds abstract floral character in mires has changed progressively through time in the carboniferous pteridophytes sphenophytes and lycophytes were dominant but by the permian gymnosperms were an important component of mire flora during the early mesozoic gymnosperms remained the characteristic mire vegetation together with pteridophytes and conifers became dominant during the jurassic cretaceous and paleocene vegetation are similar with taxodiaceous flora being important in mire vegetation from the eocene onwards however angiosperms were increasingly dominant in mire communities and in the miocene herbaceous vegetation began to play a significant role together with these changes in floral character at least three aspects of coal character also appear to vary sequentially with time and are distinctive in the tertiary 1 proportions and thickness of vitrain banding 2 coal bed thickness and 3 proportions of carbonised material a compilation has been made of data from the coal literature comparing older coals with those of the tertiary in order to give a perspective in which to examine tertiary coals it was found that only tertiary coals contain significant proportions of coal devoid of vitrain bands in addition tertiary coals are the thickest recorded coal beds and generally contain low percentages of carbonised material many less than 5 as compared to older coals it is interesting to note that paleocene coal beds are similar to cretaceous coals in that they tend to be thinner and contain higher proportions of carbonised material than do younger tertiary coals the absence of vitrain bands in some tertiary coal beds is thought to result from the floras dominated by angiosperms which are relatively easily degraded as compared to gymnosperms the thickness of tertiary coals may be related to an increase in biomass production from the carboniferous through to the tertiary as plants made less investment in producing lignin an energy intensive process in addition with less lignin in plants easier degradation of biomass may have facilitated nutrient recycling which in turn led to greater biomass production increased biomass production may have also diluted the carbonised material present in some tertiary peats leading to lower proportions in the coal another possible cause of decreased carbonised components in tertiary coal is that decreasing lignin content resulted in decreased charring during fires as lignin is particularly prone to charring a third possibility is that the carbonised component of peat may be concentrated during coalification so that tertiary coals generally of lower rank than mesozoic or paleozoic coals contain a smaller fraction of carbonised plant material it is not at present clear which of these mechanisms may have affected carbonised material in peat and coal but it is clear that lignin type and content has had an important role in determining peat and coal character since the paleozoic

the evolution of scaling laws in the sea ice floe size distribution the sub gridscale floe size and thickness distribution fstd is an emerging climate variable playing a leading order role in the coupling between sea ice the ocean and the atmosphere the fstd however is difficult to measure given the vast range of horizontal scales of individual floes leading to the common use of power law scaling to describe it the evolution of a coupled mixed layer fstd model of a typical marginal ice zone is explicitly simulated here to develop a deeper understanding of how processes active at the floe scale may or may not lead to scaling laws in the floe size distribution the time evolution of mean quantities obtained from the fstd sea ice concentration mean thickness volume is complex even in simple scenarios suggesting that these quantities which affect climate feedbacks should be carefully calculated in climate models the emergence of fstds with multiple separate power law regimes as seen in observations is found to be due to the combination of multiple scale selective processes limitations in assuming a power law fstd are carefully analyzed applying methods used in observations to fstd model output two important sources of error are identified that may lead to model biases one when observing an insufficiently small range of floe sizes and one from the fact that floe scale processes often do not produce power law behavior these two sources of error may easily lead to biases in mean quantities derived from the fstd of greater than 100 and therefore biases in modeled sea ice evolution

spike of pyrosynthetic polycyclic aromatic hydrocarbons associated with an abrupt decrease in δ13c of a terrestrial biomarker at the cretaceous tertiary boundary at caravaca spain the first vertical high resolution record of polycyclic aromatic hydrocarbons pahs of pyrosynthetic origin and the corresponding 13 c profile of a terrestrial biomarker across the cretaceous tertiary k t boundary at caravaca spain reveals the following in comparison with adjacent cretaceous marlstones the first thin horizon 0 to 0 5 cm 0 the k t boundary of the boundary clay layer is 1 enriched as much as 112 to 154 fold in typical pyrosynthetic pahs such as coronene benzo g h i perylene and benzo e pyrene and 2 shows an abrupt 13 c decrease of 1 4 1 8 in terrestrial higher plant derived n c 29 alkane the spike of pyrosynthetic pahs associated with an abrupt decrease in 13 c value of a terrestrial biomarker is interpreted to reflect the prevalence of extensive fires with subsequent 13 c decrease in atmospheric co 2 it is estimated that the geologically instantaneous combustion of 18 24 of the terrestrial above ground biomass would be necessary to account for the measured negative isotopic shift at the k t boundary on the basis of carbon mass balance between terrestrial above ground biomass and atmosphere

the influence of the spatial distribution of leads and ice floes on the atmospheric boundary layer over fragmented sea ice the response of the atmospheric boundary layer abl to subgrid scale variations of sea ice properties and fracturing is poorly understood and not taken into account in mesoscale numerical weather prediction nwp model parametrizations in this paper we analyze three dimensional air circulation within the abl over fragmented sea ice a series of idealized high resolution simulations with the weather research and forecasting wrf model is performed for several spatial distributions of ice floes and leads for two values of sea ice concentration 0 5 and 0 9 and several ambient wind speed profiles the results show that the convective circulation within the abl is sensitive to the subgrid scale spatial distribution of sea ice considerable variability of several domain averaged quantities cloud liquid water content surface turbulent heat flux thf is found for different arrangements of floes moreover the organized structure of air circulation leads to spatial covariance of variables characterizing the abl based on the example of thf it is demonstrated that this covariance may lead to substantial errors when thf values are estimated from area averaged quantities as it is done in mesoscale nwp models this suggests the need for developing suitable parametrizations of abl effects related to subgrid scale sea ice features for these models

thermohaline effects of the seasonal sea ice cover in the sea of okhotsk 1 by using a coupled ice ocean model the seasonal extent of the sea ice cover in the sea of okhotsk was examined the model results show that the sea ice at the ice edge is advected southward along sakhalin island with a mean velocity of 0 31m s into ocean water with temperatures above freezing as a result even in mid winter a large amount of ice melting occurs around the edge it results in temperature decrease in the surface mixed water during the 1993 1994 winter the total volume ratio of ice melting to ice production is estimated at 0 76 the negative latent heat flux from the ice melting is nearly comparable to the total atmospheric heat flux around the ice edge furthermore the meltwater supply to the surface layer is estimated to be approximately 3 5 times the annual amur river inflow thus it is concluded that the ice melting around the extending ice edge is a significant factor for the heat and salt balance between the sea ice and the surface mixed layer and plays an important role in the maintenance of the large seasonal sea ice extent in the sea of okhotsk

aerial observations of floe size distribution in the marginal ice zone of summer prydz bay 1 on the basis of aerial photographs of sea ice floes in the marginal ice zone miz of prydz bay acquired from december 2004 to february 2005 during the 21st chinese national antarctic research expedition image processing techniques are employed to extract some geometric parameters of floes from two merged transects covering the whole miz variations of these parameters with the distance into the miz are then obtained different parameters of floe size namely area perimeter and mean caliper diameter mcd follow three similar stages of increasing flat and increasing again with distance from the open ocean floe shape parameters roundness and the ratio of perimeter to mcd however have less significant variations than that of floe size then to modify the deviation of the cumulative floe size distribution from the ideal power law an upper truncated power law function and a weibull function are used and four calculated parameters of the above functions are found to be important descriptors of the evolution of floe size distribution in the miz among them lr of the upper truncated power law function indicates the upper limit of floe size and roughly equals the maximum floe size in each square sample area l0 in the weibull distribution shows an increasing proportion of larger floes in squares farther from the open ocean and roughly equals the mean floe size d in the upper truncated power law function is closely associated with the degree of confinement during ice breakup its decrease with the distance into miz indicates the weakening of confinement conditions on floes owing to wave attenuation the of the weibull distribution characterizes the degree of homogeneity in a data set it also decreases with distance into miz implying that floe size distributes increase in range finally a statistical test on floe size is performed to divide the whole miz into three distinct zones made up of floes of quite different characteristics this zonal structure of floe size also agrees well with the trends of floe shape and floe size distribution and is believed to be a straightforward result of wave ice interaction in the miz

sea ice melting processes inferred from ice upper ocean relationships in the ross sea antarctica 1 sea ice melting processes are inferred from various summer sea ice and upper ocean data obtained in the ross sea in january 1999 using spatially 30 km averaged continuous data an ice concentration water temperature plot ct plot shows that the temperature at a depth of 7 m increases as ice concentration decreases in the ice interior region the ct plot is explained by a simple ice upper ocean coupled model in which sea ice melting is caused only by heat input through open water the bulk heat transfer coefficient between ice and ocean kb is estimated to be 1 2 10 4 m s 1 these findings are supported by the relationship between ice concentration and heat content in the mixed layer estimated from conductivity temperature depth ctd data salinity at a depth of 7 m salt deficit in the mixed layer associated with sea ice melt estimated from ctd data and their relationships with ice concentration also suggest that melting is mainly caused by atmospheric heat input through open water and that local balance of salinity nearly hold the time evolution of ice concentration calculated from the ice upper ocean coupled model with the estimated kb corresponds with that derived from the special sensor microwave imager ssm i confirming the model s applicability and the value of kb

observing regional scale pack ice decay processes with helicopter borne sensors and moored upward looking sonars the variability of arctic pack ice parameters e g extent and ice type has been monitored by satellite borne sensors since the early 1960s and information on ice thickness is now becoming available from satellite altimeters however the spatial resolution of satellite derived ice properties is too coarse to validate fine scale ice variability generated by regional scale interaction processes that affect the coarse scale pack ice albedo strength and decay to understand these regional processes researchers rely on other data monitoring platforms such as moored upward looking sonars and helicopter borne sensors backed by observations two such regional scale pack ice decay processes are discussed the break up of large pack ice floes by long period waves generated by distant storms and the spring decay of first year ice ridges in a diverging pack ice environment these two processes although occurring on regional spatial scales are important contributors to the evolution of the total pack ice and need to be included in global climate models especially as the conditions for their occurrence will alter due to climate change

charcoal reflectance as a proxy for the emplacement temperature of pyroclastic flow deposits hot pyroclastic flow deposits often entomb and preserve vegetation as charcoal when studied in polished section this charcoal is highly reflective novel data from experimentally charred woods demonstrate that reflectance increases with both temperature and time at temperatures above 250 c reflectance rises rapidly for the first hour effectively stabilizing after 4 h for temperatures below 400 c however for higher temperatures reflectance only stabilizes after 24 h charcoalified woods from block and ash flow deposits generated by the soufriere hills volcano in montserrat have yielded interpreted deposit temperatures based on reflectance data of 325 525 c these temperatures compare favorably with directly measured data 365 640 c from the same deposits indicating that charcoal reflectance is useful as a temperature proxy for ancient pyroclastic flow deposits particularly where magnetic or mineral data are absent for this purpose however caution should be exercised as only a minimum temperature can be inferred where the heating duration of the deposit is unknown unlike magnetic or mineral data temperature data from charcoalified woods can be obtained from reworked deposits providing a valuable means of validating observations made about the style of eruption of volcanoes in ancient settings

the first report of a campanian palaeo wildfire in the west antarctic peninsula abstract the analysis of palaeofloras and the related palaeoecological conditions is of great importance for the understanding of past environmental and palaeoclimatic events in antarctica at the end of the cretaceous subtropical forests developed there because of wet and temperate climate conditions on the antarctic peninsula which is geologically characterized by a forearc context volcanic activity caused by tectonics favours the ignition of vegetation fires in the present study the occurrence of palaeo wildfires during the upper cretaceous is demonstrated for the rip point outcrop on nelson island south shetland islands during brazilian expeditions to the area macroscopic charcoal was collected and subsequently analysed under a stereomicroscope and scanning electron microscope sem the charred wood remains were identified as belonging to conifers which were important components of the antarctic palaeoflora during the cretaceous a review of the data published thus far regarding palaeo wildfires in the southern hemisphere confirms that the charcoal remains analysed here are the first to verify the occurrence of palaeo wildfires in the upper campanian levels of the west antarctic peninsula

palynofacies coal petrographic facies and depositional environments amphitheatre formation eocene to oligocene and ravenscrag formation maastrichtian to paleocene canada abstract low rank coals from two disparate geological settings have been subjected to petrographic and palynological analysis the stratigraphic units studied and their locations are the amphitheatre formation st elias mountains yukon territory of eocene to oligocene age and the base of the ravenscrag formation south central saskatchewan of latest cretaceous to earliest paleocene age the depositional setting of the amphitheatre formation ranges from distal sand dominated braided stream and lacustrine environments to proximal gravel dominated fluvial environments the coals are low in inertinite 85 in localities with a dominance of angiosperm pollen the relative abundance of eu ulminite b and densinite is greatest whereas in the ones with a dominantly coniferous pollen assemblage eu ulminite a is the most prominent maceral these observations suggest as an immediate cause effect relationship an at least partial dependance of present maceral content on floral precursors this in turn probably reflects a certain combination of depositional environment conditions ph eh temperature etc that likely controlled the plant community and the preservation of vegetal matter the depositional environment of coals from the basal part of the ravenscrag formation contrasts sharply with that of the amphitheatre the ravenscrag coals formed within a low energy stable floodplain environment palynological and coal maceral profiles for the basal ravenscrag formation coal which spans the cretaceous tertiary boundary indicates that the environment of deposition progressed from an open canopied swamp forest with areas of open water through a phase of low lying to open water swamps with herbaceous pterophytic vegetation to at least locally raised bogs the change in coal petrography across the cretaceous tertiary boundary is shown to be relatively minor in comparison to subsequent changes in coal petrography in the earliest paleocene and to changes that occur in the palynological assemblages across the boundary interval

upland ecology of some late carboniferous cordaitalean trees from nova scotia and england abstract permineralised logs and charcoal fragments composed of dadoxylon type wood and derived from cordaitalean trees are described from the upper carboniferous westphalian of nova scotia and england they exclusively occur in sandstone bodies interpreted as the deposits of braided meandering and anastomosing river channels the architecture and ecology of this type of cordaitalean has not yet been satisfactorily described estimates of tree height using an allometric approach suggest that the largest trees attained an approximate height of ca 45 m the absence of true growth rings in the logs indicate that they grew under non seasonal humid tropical conditions however the presence of charred wood fragments implies that droughts of sufficient intensity to permit wildfire did occasionally occur the charcoal fragments are usually associated with incised poorly sorted chaotically bedded channel facies interpreted as flood deposits dramatic increases in runoff and sediment discharge are known to follow the destruction of vegetation in modern wildfire events and the high energy charcoal bearing channel facies described may represent a similar geomorphic response to cordaitalean vegetation fires geomorphic sensitivity to fire is greatest for steeply sloping terrains and it is therefore probable that the cordaitaleans described in this paper occupied upland settings this palaeoecological interpretation is supported by occurrence of the cordaitalean remains in river channel deposits immediately downstream of regions of palaeo upland and by the palynological record the presence of upland forests in late carboniferous times has important implications for numerical modelling of global geochemical cycles

possible solutions to several enigmas of cretaceous climate the nature of the warm climates of the cretaceous has been enigmatic since the first numerical climate models were run in the late 1970s quantitative simulations of the paleoclimate have consistently failed to agree with information from plant and animal fossils and climate sensitive sediments the cold continental interior paradox first described by deconto et al in barrera e johnson c eds evolution of the cretaceous ocean climate system vol 332 geological society of america special paper boulder pp 391 406 1999 has been an enigma with extensive continental interiors especially in northeast asia modeled as below freezing in spite of plant and other evidence to the contrary we reconsider the paleoelevations of specific areas particularly along the northeastern siberian continental margin where paleofloras indeed indicate higher temperatures than suggested by current climate models evidence for significant masses of ice on land during even the otherwise warmest times of the cretaceous is solved by reinterpretation of the 18o record of fossil plankton the signal interpreted as an increase in ice volume on land is the same as the signal for an increase in the volume of groundwater reservoirs on land the problem of a warm arctic where fossil floras indicate that they never experienced freezing conditions in winter could not be solved by numerical simulations using higher co2 equivalent greenhouse gas concentrations we propose a solution by assuming that paleoelevations were less than today and that there were much more extensive wetlands lakes meandering rivers swamps bogs on the continents than previously assumed using 8 co2 equivalent greenhouse gas concentrations and assuming 50 75 water surfaces providing water vapor as a supplementary greenhouse gas on the continents reduces the meridional temperature gradients under these conditions the equatorial to polar region temperature gradients produce conditions compatible with fossil and sedimentological evidence

statistical investigation of horizontal propagation of gravity waves in the ionosphere over europe and south africa 1 a statistical investigation into the horizontal propagation of 8 30 min gravity waves gws in the ionosphere over a 1 year period from june 2010 to may 2011 is presented the gws were observed by multipoint continuous doppler sounding systems installed in the czech republic and in the western cape south africa measurements of gw propagation in the ionosphere over south africa have never been presented before simultaneous measurements from nearby ionosondes made it possible to estimate the height of the gw observations and show that the analyzed gws propagated at altitudes from 150 to 250 km the analyzed waves were mainly observed after sunrise and around sunset our statistical study shows that the analyzed gws propagated with horizontal velocities from 70 to 250 m s the average observed horizontal velocities were 100 m s in the local summer and 125 150 m s in the local winter the waves propagated approximately poleward in the local summer whereas roughly equatorward propagation was observed in the local winter westward propagation was rarely observed in the czech republic and eastward southeast propagation was seldom observed in south africa a comparison with neutral wind velocities shows that the analyzed gws propagated approximately against the neutral winds calculated by the hwm07 model the estimated horizontal wavelengths of the analyzed waves were 100 300 km

polycyclic aromatic hydrocarbons of pyrolytic origin in ancient sediments evidence for jurassic vegetation fires abstract polycyclic aromatic hydrocarbon pah distributions in an upper jurassic succession from offshore korea bay basin were consistent with a pyrolytic source being dominated by non alkylated species levels of these pahs were significantly higher in samples containing abundant fusinite macerals which are believed by some to be the product combustion the data were consistent with a pah origin from periodic conflagration throughout the upper jurassic of vegetation adjacent to a tectonically formed lake distribution of pahs exhibited some differences from those of combustion origin in recent and some ancient sediments and were characterized by the dominance of the highly peri condensed compounds benzo e pyrene benzo g h i perylene and coronene this characteristics reflects either preferential formation or preferential preservation under the prevailing sedimentary conditons of the highly peri condensed structures

a wave based model for the marginal ice zone including a floe breaking parameterization 1 the marginal ice zone miz is the boundary between the open ocean and ice covered seas where sea ice is significantly affected by the onslaught of ocean waves waves are responsible for the breakup of ice floes and determine the extent of the miz and floe size distribution when the ice cover is highly fragmented its behavior is qualitatively different from that of pack ice with large floes therefore it is important to incorporate wave ice interactions into sea ice ocean models in order to achieve this goal two effects are considered the role of sea ice as a dampener of wave energy and the wave induced breakup of ice floes these two processes act in concert to modify the incident wave spectrum and determine the main properties of the miz a simple but novel parameterization for floe breaking is derived by considering alternatively ice as a flexible and rigid material and by using current estimates of ice critical flexural strain and strength this parameterization is combined with a wave scattering model in a one dimensional numerical framework to evaluate the floe size distribution and the extent of the miz the model predicts a sharp transition between fragmented sea ice and the central pack thus providing a natural definition for the miz reasonable values are found for the extent of the miz given realistic initial and boundary conditions the numerical setting is commensurate with typical ice ocean models with the future implementation into two dimensional sea ice models in mind

the seasonal evolution of sea ice floe size distribution the arctic sea ice cover undergoes large changes over an annual cycle in winter and spring the ice cover consists of large snow covered plate like ice floes with very little open water by the end of summer the snow cover is gone and the large floes have broken into a complex mosaic of smaller rounded floes surrounded by a lace of open water this evolution strongly affects the distribution and fate of the solar radiation deposited in the ice ocean system and consequently the heat budget of the ice cover in particular increased floe perimeter can result in enhanced lateral melting we attempt to quantify the floe evolution process through the concept of a floe size distribution that is modified by lateral melting and floe breaking a time series of aerial photographic surveys made during the sheba field experiment is analyzed to determine evolution of the floe size distribution from spring through summer based on earlier studies we assume the floe size cumulative distribution could be represented by a power law d where d is the floe diameter the exponent as well as the number density of floes ntot are estimated from measurements of total ice area and perimeter as summer progressed there was an increase in as the size distribution shifted toward smaller floes and the number of floes increased lateral melting causes the distribution to deviate from a power law for small floe sizes

antarctic sea ice extent during the holocene reconstructed from inland ice core evidence 1 interannual fluctuations in the antarctic sea ice extent sie affect the global albedo and heat balance and they may affect global co2 levels we found that the annual trend of sodium ion fluxes in the snowpack in the dome fuji region of east antarctica can serve as a proxy for the present day sie in the southern indian ocean and weddell sea sectors we then used sodium ion profiles obtained from the dome fuji ice core to reconstruct the sie during the holocene we observed that 1 the beginnings of both the climatic optimum 12 0 ka bp and neoglaciation 5 4 ka bp in the southern ocean indicated by siliceous microfossil records are consistent with decreases 11 8 ka bp and increases 5 4 ka bp in the sodium ion fluxes in the dome fuji ice core and 2 the interannual fluctuation in the sie during some periods of the neoglaciation was greater than the interannual fluctuation during the climatic optimum

fire and aspect induced differences on the erodibility and hydrology of soils at la costera valencia southeast spain this paper presents measurements of soil aggregation parameters and rainfall simulation experiments from areas of mediterranean scrubland vegetation in la costera district in the southern part of valencia province spain data were obtained using a portable rainfall simulator and from laboratory studies of aggregate stability using the water drop test and ultrasonic dispersion methods three locations were chosen to enable the influences of aspect and the post fire recovery time of the vegetation on soil erosion and hydrology to be investigated the slopes studied were a a north facing slope burnt ten years before the experiment b a south facing slope burnt at the same time and c a north facing slope burnt two years before the experiment similar to slope a in terms of its basic characteristics the experiments demonstrate the importance of both wildfires and aspect on hydrological and erosional soil surface processes the north facing slope at la costera slope a has a higher aggregate stability than the corresponding south facing slope slope b the recently burnt north facing slope c is intermediate in terms of aggregation but has the most erodible soils because of the lower infiltration rates and the low vegetation and litter cover nevertheless for the slopes burnt ten years previously the south facing slope is more erodible than the north facing one the results suggest that the forest fire ten years ago did not produce a persistent degradation of the ecosystem only higher soil and water losses during the first years following the fire a southern aspect where vegetation recovery rates are slower and the hydraulic stress is higher favours the development of soils with a relatively low aggregate stability

widespread inflation and drainage of a pāhoehoe flow field the nesjahraun þingvellir iceland this study describes the emplacement of the nesjahraun a basaltic lava flow that entered the lake ingvallavatn sw iceland high resolution remotely sensed data were combined with fieldwork to map the flow field onshore the nesjahraun exhibits a variety of textures related to the widespread inflation and collapse of a p hoehoe flow field its emplacement is interpreted as follows initially the eruption produced sheet p hoehoe in the central part of the flow field the lava has a platy ridged surface which is similar to some other lava flows in iceland and on mars here the texture is interpreted to have formed by unsteady inflation of the brittle crust of stationary sheet p hoehoe causing it to break into separate plates the ridges of broken p hoehoe slabs formed as the plates of crust moved vertically past each other in a process similar to the formation of shatter rings upstream fresh lava overflowed repeatedly from channels and tubes covering the surface with shelly p hoehoe formation of a 250 m wide open channel through the flow field allowed the inflated central part of the flow to drain rapidly this phase produced a lava which eroded the channel walls carrying broken p hoehoe slabs lava balls and detaching large 200 m long rafts of compound shelly p hoehoe lava much of this channelized lava flowed into the lake leaving a network of drained channels and tubes in the upstream part of the flow as in other locations the platy ridged texture is associated with a low underlying slope and high eruption rate here its formation was possibly enhanced by lateral confinement hindered entry into the lake and an elevated vent location we suggest that formation of this type of platy ridged lava where the plates are smooth and the ridges are slabs of broken p hoehoe can occur without significant horizontal transport as the surface crust is broken into plates in situ this reconstruction of the emplacement of the nesjahraun also demonstrates that high resolution aerial survey data are extremely useful in the mapping and measurement of lithofacies distributions in large flow fields but that fieldwork is still necessary to obtain the detailed textural information necessary to interpret them

charcoal taphonomy and significance in geology botany and archaeology abstract charcoal occurs in the natural environment as either a result of wildfire or volcanic processes in addition people may make charcoal either for domestic or industrial use charcoal may be used as a fuel for domestic heating and cooking through a range of industrial uses such as iron smelting more recently the charcoalification process has been used to make biochar that is relatively inert and promotes atmospheric co 2 reduction with such a wide range of uses research has been published in a broad range of journals and often whole areas of study are unfamiliar to other charcoal researchers here we review a range of charcoal studies and their inter relationships we present some of the results of a major international meeting on charcoal brussels september 2008 highlighting the potential of charcoal studies as part of palaeoenvironmental investigations both in a geological and archaeological context

end cretaceous devastation of terrestrial flora in the boreal far east a continuous marine sedimentary sequence spanning the cretaceous tertiary k t boundary has been identified in eastern hokkaido japan on the basis of planktonic foraminifera the k t boundary is marked by a 6 10 cm thick layer of pyrite rich fossil poor greyish black claystone1 which is lithologically similar to the well known boundary clay of the classical european k t boundary sections2 4 we show here that terrestrial palyno morphs from the hokkaido section record sudden changes in the floristic composition precisely at the base of the boundary claystone layer in particular both angiosperm and gymnosperm pollen abundances decline markedly and these changes are accompanied by an abrupt rise in the proportion of fern spores return to the original moderate level of fern dominance occurs within a few centimetres above the boundary layer a sharp increase of fern spores has also been reported at the palynologically defined k t boundary in the western interior of north america5 which coincides with the top of an iridium rich clay layer6 7 the possibly synchronous occurrence of analogous floral changes at these widely separated regions implies a devastation of the land flora which although geologically brief was intercontinental in scope and which was probably caused by a major catastrophic event such as the impact of a massive meteorite7

petrology of fibrous coal fusain and associated inertinites from the early paleocene of the central alberta plains abstract megascopic micropetrographic and scanning electron microscopic investigations of fibrous coal indicate that paleo wildfires were common occurrences in the mire which produced highvale coals at least 20 fibrous coal fusain horizons have been identified in corehole samples from the pit no 3 locality at highvale in the central alberta plains thicknesses of individual horizons vary and are not particular to any stratigraphic position within coal seams the majority of these fibrous horizons is within the two thick economic seams the highvale nos 1 and 2 which are characteristically megascopically dull the dullness of given lithotypes is largely related to inertinite content with fibrous coal containing 51 inertinite on average and selected horizons comprised of as much as 85 inertinite semifusinite and inertodetrinite are the predominant inertinites with a few horizons exhibiting highly reflecting fusinite macrinite is rare and micrinite is absent sem investigations reveal that certain fibrous coals exhibit excellent preservation of the original gymnospermous taxodium woody tissue features such as homogenization and swelling of the cell walls elimination of the middle lamellae and preservation of bordered pits are clearly indicative of charcoal formation as a product of paleo wildfires depending upon the nature of the fire temperatures obtained and the nature of the mire vegetation a wide range of inertinite precursors can be produced

organic facies development within middle jurassic coal seams danish central graben and evidence for relative sea level control on peat accumulation in a coastal plain environment abstract during middle jurassic times peat accumulated in coastal plain environments in an overall transgressive setting in the sogne basin danish central graben in the north sea the coal seams occur in nonmarine to marginal marine deposits coal petrographic analyses of the seams in the west lulu 2 well supplemented with a sequence stratigraphic analysis suggest that peat accumulation was controlled by relative sea level changes in west lulu 2 the coal bearing upper part of the middle jurassic is divided into sequences a and b the sediments of sequence a are part of a transgressive systems tract whereas the overlying sequence b contains lowstand and transgressive systems tract deposits the coals are situated in the transgressive systems tracts the coal seams formed during a rapid relative sea level rise are generally characterized by petrographic features related to a permanently high groundwater table coals formed during a slow rise typically are drier in their petrographic composition the highest pyrite contents are observed in the wet coals the coal seams represent terrestrial equivalents to marine flooding surfaces or to transgressive surfaces if they are situated at the base of a transgressive systems tract a thick coal seam zone is associated with the stratigraphic level of the maximum flooding surface which correlates with the time of formation of the highest accommodation space

particle motion and the theory of charcoal analysis source area transport deposition and sampling principles from particle motion physics were applied to recurring problems of the interpretation of stratigraphic charcoal data 1 fires within catchments of lakes often produce no record in fossil charcoal curves and 2 periods characterized by no local fire e g 20th century fire suppression often display as much charcoal as times when local fire was frequent quantitative theory on source area transport deposition and sampling of charcoal shows the relationship between particle sizes counted by alternative methods of charcoal analysis pollen slides for particles 5 80 m in diameter petrographic thin sections for particles 50 10 000 m diameter and charcoal diagrams the relationship between diameter and critical and deposition velocities results in fundamental aerodynamic differences between the sizes of particles quantified by the two methods charcoal recorded on pollen slides is of a size that is difficult to lift but once entrained it remains in suspension thin section charcoal is lifted at relatively low wind velocities but it is not suspended at normal surface wind speeds thermal buoyancy during fire lofts charcoal above the forest canopy depending on particle size and wind speed pollen slide charcoal sizes are underrepresented near the fire because they remain in suspension and are preferentially exported from the burn area thin section charcoal is convected to lower heights on average and is deposited nearby following fire thin section charcoal is redistributed locally by wind and thus may enter lakes because of cohesive forces and aerodynamics more pollen slide charcoal remains on the ground and less enters lakes source areas for pollen slide charcoal are subcontinental to global and diagrams of pollen slide charcoal are biased toward nonlocal charcoal they can be used to interpret importance of fire for broad spatial and temporal scales thin section charcoal represents the catchment fire regime simulation models that generate charcoal during fire mix sediments and then sample at specified intervals indicate that 1 in the absence of sediment mixing the pollen slide method should consistently resolve individual fires that occur with an expectation of 30 50 yr 2 unless samples are continuous neither method will produce useful estimates of fire frequency and 3 even a modest amount of sediment mixing will obscure the signal

fracture of summer perennial sea ice by ocean swell as a result of arctic storms 1 the arctic summer minimum sea ice extent has experienced a decreasing trend since 1979 with an extreme minimum extent of 4 27 106 km2 in september 2007 and a similar minimum in 2011 large expanses of open water in the siberian laptev chukchi and beaufort seas result from declining summer sea ice cover and consequently introduce long fetch within the arctic basin strong winds from migratory cyclones coupled with increasing fetch generate large waves which can propagate into the pack ice and break it up on 06 september 2009 we observed the intrusion of large swells into the multiyear pack ice approximately 250 km from the ice edge these large swells induced nearly instantaneous widespread fracturing of the multiyear pack ice reducing the large 1 km diameter parent ice floes to small 100 150 m diameter floes this process increased the total ice floe perimeter exposed to the open ocean allowing for more efficient distribution of energy from ocean heat fluxes and incoming radiation into the floes thereby enhancing lateral melting this process of sea ice decay is therefore presented as a potential positive feedback process that will accelerate the loss of arctic sea ice