landslides and climate change in the italian dolomites since the late glacial abstract the paper deals with the relationship between the temporal occurrence of landslides and climatic changes in the italian dolomites since the late glacial after an introduction on the state of the art with particular reference to the alpine region the results of recent investigations in the two study sites are illustrated at cortina d ampezzo several landslides were dated mainly by the radiocarbon method the most ancient landslide event there involved large rock slides which affected the dolomitic slopes following the withdrawal of glaciers after the last glacial maximum lgm and also slides and flows mainly occurring in pelitic materials of the valley floors from 13 000 to 10 000 cal bp a later series of flows occurred between 5500 and 2500 cal bp in the upper badia valley alta badia the most ancient events go back to 10 000 and 9000 cal bp and correspond with earth flows that followed vast rotational slides affecting the bedrock up to a depth of about 50 m more recent earth flows involving more modest amounts of material took place between 6500 and 2300 cal bp by analysing the dates from the two study areas it was possible to correlate the recorded increase of landslide activity with the climatic changes occurring at the boundary between the late glacial and the holocene and between the atlantic and the subboreal and to compare the results with those derived from other european regions the types and causes of landslides taking place in these two periods were substantially different reflecting the different morphoclimatic conditions that existed in the two areas when these mass movements were triggered finally notwithstanding the importance of non climatic causes such as geological structural factors and possible human influences it is concluded that many of the dated landslides can be considered as indicators of climatic change

geomorphological study of the fadalto landslide venetian prealps italy abstract this research deals with the fadalto landslide lapisina valley venetian prealps which took place in the lateglacial and has continued its activity until today our aim is to recognize how the landslide failed the causes of such failure and the activity of this landslide the study of this landslide is important not only to understand the geomorphological history of this alpine area and why the piave river modified its course in the late pleistocene but also the links with human activities and specifically with the road and rail network the geomorphological study carried out by the interpretation of aerial photos and by a detailed field survey has been integrated with a geological survey geophysical investigations and a morphometric analysis dtm the fadalto landslide is considered to be a rockslide reactivated in various phases with different dimensions and with different characters slides slumps and flows the landslides have been provoked by natural causes both external and internal the fundamental external causes are the retreat of the wurmian glacier and tectonic activity the internal factors that decrease the shear resistance are the bedding planes and joints of the bedrock the attitude of the rocks dipping towards the valley bottom and as regards more recent failures the presence of glacial deposits underlying the landslide debris besides in recent times we must also consider human activity as a cause of slope instability as to the activity the fadalto landslide is defined dormant this means that in this area there is a geomorphological risk connected with the important road and rail network of the lapisina valley

a continuum model of melt pond evolution on arctic sea ice 1 during the northern hemisphere summer absorbed solar radiation melts snow and the upper surface of arctic sea ice to generate meltwater that accumulates in ponds the melt ponds reduce the albedo of the sea ice cover during the melting season with a significant impact on the heat and mass budget of the sea ice and the upper ocean we have developed a model designed to be suitable for inclusion into a global circulation model gcm which simulates the formation and evolution of the melt pond cover in order to be compatible with existing gcm sea ice models our melt pond model builds upon the existing theory of the evolution of the sea ice thickness distribution since this theory does not describe the topography of the ice cover which is crucial to determining the location extent and depth of individual ponds we have needed to introduce some assumptions we describe our model present calculations and a sensitivity analysis and discuss our results

melt ponds on sea ice in the canadian archipelago 2 on the use of radarsat 1 synthetic aperture radar for geophysical inversion microwave scattering from a first year sea ice fyi melt ponded surface is examined using radarsat 1 synthetic aperture radar sar data collected during the 1997 collaborative interdisciplinary cryospheric experiment c ice 97 near resolute bay nunavut this paper 1 investigates the utility of time series of microwave scattering to detect melt pond formation and 2 investigates approaches toward geophysically inverting information on the physical and radiative properties of this surface we found melt pond formation to coincide with a sharp rise in the temporal evolution of the microwave scattering coefficient over fyi radarsat 1 incidence angle and surface wind speed explained 90 of the variation in radarsat 1 was sensitive r2 0 80 to the fractional coverage of melt ponds during windy conditions 5 3 m s 1 spatial and temporal coincident measurements of radarsat 1 and the integrated shortwave albedo revealed a strong negative statistical correlation r2 0 91 during windy conditions 5 3 m s 1 a weaker but strong negative relationship r2 0 78 was observed for less windy conditions 3 2 m s 1 and a very weak positive relationship r2 0 19 was found for low wind speed conditions 1 5 m s 1 all relationships were observed for melt pond fractions between 13 and 34

late glacial climatic changes in eastern france lake lautrey from pollen lake levels and chironomids high temporal resolution analyses of pollen chironomid and lake level records from lake lautrey provide multi proxy quantitative estimates of climatic change during the late glacial period in eastern france past temperature and moisture parameters were estimated using modern analogues and plant functional types transfer function methods for three pollen records obtained from different localities within the paleolake basin the comparison of these methods shows that they provide generally similar climate signals with the exception of the bolling comparison of pollen and chironomid based temperature of the warmest month reconstructions generally agree except during the bolling major abrupt changes associated with the oldest dryas bolling allerod younger dryas and the younger dryas preboreal transitions were quantified as well as other minor fluctuations related to the cold events e g preboreal oscillation the temperature of the warmest month increased by not vert similar5 c at the start of bolling and by 1 5 3 c at the onset of the holocene while it fell by ca 3 to 4 c at the beginning of younger dryas the comparative analysis of the results based on the three lautrey cores have highlighted significant differences in the climate reconstructions related to the location of each core underlining the caution that is needed when studying single cores not taken from deepest part of lake basins

modelling the evolution of supraglacial lakes on the west greenland ice sheet margin we present a model study investigating the summer evolution of supraglacial lakes on the greenland ice margin using a one dimensional 1 d model we calculate the surface ablation for a bare ice surface and beneath supraglacial lakes for 30 days in the summers of 1999 and 2001 the surface ablation beneath the lake was enhanced by 110 in 1999 and 170 in 2001 compared with the ablation for bare ice we then use the results from the 1 d model to further model the vertical and horizontal evolution of the supraglacial lakes the results of which are compared with satellite images within the region of the ice sheet where supraglacial lakes presently occur the area covered by supraglacial lakes is found to be more or less independent of the summer melt rate but controlled by topography we therefore predict that inside this region the area covered by supraglacial lakes will remain constant even in a warmer climate however in a warmer climate surface melting will occur higher on the ice sheet where small surface slopes favour formation of large supraglacial lakes enhanced surface melting beneath such lakes is a hitherto overlooked feedback mechanism related to climate warming

a lacustrine record of early holocene watershed events and vegetation history corvara in badia dolomites italy the early middle holocene lacustrine succession of corvara in badia italian dolomites 1521 m a s l records landslides and other watershed events before the onset of human pressure the sensitivity of this archive to relate climate change watershed processes and vegetation dynamics in the catchment has been explored through a stratigraphic study including the analysis of sedimentological features magnetic properties palaeobotanical records and radiocarbon dating a palaeolake existed between 10 1 k and 7 k cal yr bp and was surrounded by a dense conifer forest long term forest dynamics driven by ecological processes and by climatic conditions favourable to upward forest expansion is recorded throughout the pollen record within the fine clastic sedimentation distinct layers enriched in organic debris of terrestrial origin have been attributed to instant events produced by mass movements their age fits the chronology of large landslide events already known in the catchment enabling correlation of the field evidence of landslides with the lacustrine record landslide frequency is controlled by geological and structural factors but it is significantly modulated by the centennial millennial climatic phases that characterise the holocene in the alps the taphonomical properties of pollen and macroremains provided valuable insight on the mechanism of watershed processes copyright 2006 john wiley sons ltd

the amphi atlantic distribution of the younger dryas paleoclimatic oscillation abstract interest in significant climatic fluctuations affecting large geographic areas but having a time range that is too brief to adduce the milankovitch radiation cycles has focused on the allerod younger dryas event which is a well established phenomenon of western europe manifested by glacial and vegetational reconstructions it is also shown by the foraminiferal evidence for shifts in the polar front in the north atlantic recent pollen and lithostratigraphic investigations in the maritime provinces of eastern canada and in the till plains of west central ohio on opposite sides of the late glacial spruce forest indicate that the event also left a record in eastern north america experiments with an atmospheric general circulation model with the temperature of north atlantic surface waters depressed to full glacial levels lowered summer temperatures in upwind periglacial eastern north america by 2 c just as far inland as they did downwind in western europe where the paleoecological record of cooling is clear a leading hypothesis for the cause for the younger dryas cooling appeals to the influx of tabular icebergs released from arctic ice shelves around the wasting scandinavian and siberian ice sheets during the allerod warming the resulting cooling of the north atlantic waters during the younger dryas could be facilitated or precipitated by the abrupt influx of glacial meltwater derived from almost the entire southern margin of the laurentide ice sheet and emerging from the gulf of st lawrence as brought about by a major shift in drainage direction from the mississippi river to the st lawrence river about 10 8 ka bp a supplemental influx of fresh water may have come from the contemporaneous drainage of the baltic ice lake the diversion of laurentide meltwater to the atlantic was caused by retreat of an ice lobe in northwestern ontario north of minnesota allowing the huge glacial lake agassiz in saskatchewan and manitoba to drain into the great lakes and more than double the inflow of meltwaters in the north atlantic thereby diverting the gulf stream and permitting the influx of icebergs from the north to cool the ocean surface minor readvance of the ice lobe about 10 ka bp temporarily diverted the lake agassiz drainage to the south with the final retreat of the ice the drainage again went to the east but by this time the ice sheets were much diminished and the regional climate had warmed enough so that the effects of the meltwater flux on the gulf stream were muted and the ice sheets bordering the north atlantic had retreated onto the land and no longer delivered enough icebergs to cool the surface waters the younger dryas interval thus was terminated and the warming manifested in the allerod was renewed

a new greenland deep ice core the polar ice sheets are rich sources of information on past atmospheric conditions including paleoclimates a new deep ice core has been drilled in south greenland comparison of the oxygen isotopic profile with that from camp century and with a deep sea foraminifera record indicates that the new core reaches back to about 90 000 years before present in a continuous sequence the details in the wisconsin part of the ice core records seem to be climatically significant and the general trends reveal all of the relevant emiliani stages recorded in deep sea cores the redated camp century record suggests a dramatic termination of the eem sangamon interglacial

the dinaric fault system large scale structure rates of slip and plio pleistocene evolution of the transpressive northeastern boundary of the adria microplate located at the northeastern corner of the adria microplate the alps dinarides junction represents a key region for understanding how the adria microplate interacts with stable europe however little is known on how the present day deformation imposed by the rotation of the adria microplate is absorbed across the dinarides using morphotectonic analysis based on satellite and aerial images accurate topographical maps and digital elevation models combined with field investigations we mapped in detail the three main active faults of the northern dinarides geomorphic and geological cumulative displacements ranging from a few meters to several kilometers have been identified on those faults and dated for the most recent ones using 36 cl exposure dating those results yielded a total right lateral motion of 3 8 0 7 mm yr oriented n317 comparing our results with the motion expected from adria rotation models suggests that the northern dinarides absorbs most of the predicted adria eurasia motion thus representing the eastern boundary of the microplate however a significant e w component is lacking suggesting that part of the stress imposed by the microplate rotation is transferred farther to the east finally bounds placed on the plio pleistocene kinematics confirm that faulting onset occurred during the early pliocene and evidence a significant kinematic change at the early middle pleistocene boundary

a 15 000 year isotopic record from lake zurich of deglaciation and climatic change in switzerland abstract ostracod and pelecypod carbonate preserved since the latest pleistocene in the bottom sediments of lake zurich was probably formed under constant temperature conditions temporal shifts in the oxygen isotype ratios for those carbonates therefore correspond to shifts in the isotopic character of the net lake inflow alpine deglaciation which released isotopically light meltwaters commenced prior to ca 15 000 yr b p and was essentially completed in northern switzerland by 12 4000 250 yr b p well before substantially increased atmospheric heat was available from either increased insolation or an increased atmospheric co 2 content the early holocene climate for the region was characterized by minor short term fluctuations in mean annual air temperatures and an overall amelioration of up to 2 c contemporaneously precipitated authigenic and biogenic carbonates have recorded partitioning of carbon isotopes between surface and bottom waters during photosynthetic production and subsequent oxidation of organic matter in the lake the degree of that partitioning provides an index of the relative production rates which were low in the late pleistocene meltwater lake but considerably enhanced during the holocene

theoretical estimates of light reflection and transmission by spatially complex and temporally varying sea ice covers the reflection absorption and transmission of light at visible and near infrared wavelengths by snow and ice covers is important for a number of geophysical problems the focus of this paper is on the reflection and transmission of light by spatially inhomogeneous and temporally varying sea ice covers this is investigated using a two stream multilayer radiative transfer model in the wavelength region from 400 to 1000 nm the model is computationally simple and utilizes the available experimental data on the optical properties of sea ice the ice cover is characterized as a layered medium composed of selections from nine distinct snow and ice types three case studies are presented illustrating values of spectral albedo transmittance and transmitted photosynthetically active radiation par for 1 a spatially inhomogeneous ice cover 2 a uniform ice cover as it undergoes a melt cycle and 3 a temporally changing spatially variable ice cover results indicate that small scale horizontal variations in snow depth and ice thickness can cause light transmission to change over 3 orders of magnitude dramatic changes in light reflection and transmission are predicted in the early part of the melt season as the ice cover evolves from an opaque snow covered medium to translucent bare or ponded ice

the first continuous late glacial holocene peat bog multi proxy record from the dolomites ne italian alps abstract paleoclimate and paleoenvironmental studies in the north eastern italian alps have been hampered by the rarity of well preserved high altitude deposits and the lack of high resolution multi proxy records with adequate chronological control this paper presents the first complete late glacial to holocene peat succession from the dolomites danta di cadore belluno italian alps a 7 m core was used to evaluate the potential of the ombrotrophic val di ciampo peat deposit 1400 m a s l as an archive of environmental and climate change the depth age scale is based upon independent 14 c and 210 pb dates and combined with peat stratigraphy demonstrates that the peat core covers more than 13 200 cal bp extending to the end of the last part of the late glacial bulk density inorganic matter content pore water ph conductivity ca mg ratios and ca sr and ti trends were used to identify changes in trophic conditions through the bog the boundary between ombrotrophic and minerotrophic conditions occurs at approximately 400 cm below the surface and demonstrates that this core is the longest eastern alpine ombrotrophic record yet obtained corresponding to 7000 cal bp the high resolution chemical data of this peat archive improves our understanding of european alpine holocene climate variability and the relationship between natural climate fluctuations and anthropogenic climate change during the present interglacial in the dolomites

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

delineation of intrabasin structure in a dilational jog of the san jacinto fault zone southern california three high resolution seismic reflection lines were acquired in the northern part of the san jacinto graben the graben a pull apart basin formed by a dilational right step of the san jacinto fault zone has been previously interpreted as a simple rhombochasm the reflection survey located at least one significant and previously unidentified intrabasin fault referred to here as the farm road strand this fault lies approximately halfway between the claremont and casa loma strands of the san jacinto fault zone at the north end of the basin the southwestern boundary of the graben is interpreted to be the newly identified farm road strand and not the casa loma strand as was previously thought the identification of this intrabasin fault allows us to infer that the san jacinto basin comprises coalescing subbasins and is not a simple pull apart basin with an unusually large length width ratio the distances between the en echelon casa loma farm road and claremont strands are between 1 and 2 km this close spacing would likely permit an earthquake rupture to jump between strands and thus propagate through the san jacinto basin

eoalpine and mesoalpine tectonics in the southern alps according to structural and stratigraphic data eoalpine and mesoalpine tectonics can be clearly recognized in the southern alps and distinguished from the better known neoalpine deformation

application of geomorphons for analysing changes in the morphology of a proglacial valley case study the scott river sw svalbard abstract the progressive degradation of the cryosphere of high arctic areas causes an increase in the dynamics of geomorphic processes that shape the valleys of rapidly retreating glaciers those especially sensitive to global environmental changes are the small land ending valley glaciers that are in the phase of strong retreat under these conditions the river valley s floors that are drained by proglacial waters are constantly undergoing intensive changes for the analysis of these changes two methods were used simultaneously as a synthesis to allow for quantitative and qualitative evaluation the first one is the increasingly more common dod method dem of difference which allows quantifying volumetric changes as a result of topographic differentiation the second one which was applied for the first time on a small valley spatial scale is the geomorphons method that makes it possible to assess the stability of landforms and to determine the directions of their new development to judge the applicability advantages and disadvantages of both methods for analysis of geomorphic changes in rapidly changing proglacial environments the study was carried out over a 3 3 km distance of the non glaciated section of the scott river valley course nw wedel jarlsberg land sw svalbard this area 1 3 km2 is currently shaped by a braided gravel bed river more accurately the study focused on the section spanning from the glacier terminus which is the source of the scott river to its outlet at the rechersche fjord bellsundfiorden the foundation for the development of comparative elevation models was a collection of terrestrial laser scanning tls surveys that were taken with a leica scanstation c10 scanner during the 2010 and 2013 snowmelt seasons on the basis of these surveys and with the use of tin interpolation high resolution 0 2 m digital terrain models dtms were generated the dtm models that had been prepared in this manner were used for the analysis of surface changes by employing geomorphic change detection gcd software and by simultaneously generating geomorphons maps for four selected test areas that covered characteristic fragments of the valley bottom 1 on the close forefield of the scott glacier terminus 2 in the immediate vicinity of the narrow valley outlet at the foot of the marginal moraine ridge 3 in the enlargement of the central section of the non glaciated valley floor 4 within the alluvial fan outlet to the fjord a comparison of the obtained results dod and geomorphons maps zonal statistics as well as a compilation of both the quantitative assessment of the scale of changes and the qualitative assessment of the transformation s direction allowed for reconstructing the range and rate of three year long changes in morphology at the analysed sections of the valley floor it was found that the pattern and rate of changes were closely related to the location of the test areas in the scott river s catchment system significant differences in the dynamics of processes shaping the valley landforms along the longitudinal valley course were found

absolute dating of the late glacial period in switzerland using annually laminated sediments abstract results of a high resolution late glacial ams 14 c chronology from rotsee central switzerland have given evidence that the atmospheric radiocarbon concentration was not constant between 13 000 and 9500 yr b p this resulted in three marked phases of constant radiocarbon age at 12 700 at 10 000 and at 9500 yr b p new results of a late glacial varve chronology from soppensee central switzerland suggest that the younger two phases of constant 14 c age each had a duration of ca 400 calendar years the length of the late glacial chronozones has been calculated on the basis of these replicate varve counts and a comparison with their estimated duration in radiocarbon years shows that the estimated duration of the chronozones bolling ca 800 calendar yr vs 1000 14 c yr and younger dryas ca 900 calendar yr vs 1000 14 c yr agree with the expected time span whereas the estimated duration of the allerod chronozone ca 400 calendar yr vs 1000 14 c yr is substantially shorter than expected furthermore a tentative comparison of varve ages and 14 c ages suggests that the varve chronology is more than 1000 yr offset toward older ages from the radiocarbon chronology during the late glacial period

environmental and climatic conditions at a potential glacial refugial site of tree species near the southern alpine glaciers new insights from multiproxy sedimentary studies at lago della costa euganean hills northeastern italy abstract it has been hypothesized that refugia of thermophilous tree species were located in northern italy very close to the alps though this hypothesis has yet to be tested thoroughly in contrast to central and southern italy with its relative wealth of data only a few fragmentary records are currently available from northern italy for the last glacial wurm weichselian our new study site lago della costa lies adjacent to the catchment of the megafans of the alpine forelands and the braided rivers of the northeastern po plain that have so far inhibited the recovery of continuous glacial and late glacial records we analyze pollen plant macrofossils charcoal and ostracods to reconstruct the vegetation fire and lake history for the period 33 000 16 000 cal bp we compare our data with glacial records from southern europe to discuss similarities and dissimilarities between these potential refugial areas a comparison with independent paleoclimatic proxies allows to assess potential linkages between environmental and climatic variability new macrofossil and pollen data at lago della costa unambiguously document the local persistence of boreal tree taxa such as larix decidua and betula tree species around the study site during the last glacial the regular occurrence of pollen of temperate trees in the organic lake sediments fine detritus calcareous gyttja suggests that temperate taxa such as corylus avellana quercus deciduous tilia ulmus fraxinus excelsior carpinus abies alba and fagus sylvatica most likely survived the last glacial maximum lgm at favorable sites in the euganean hills the percentage values of temperate trees are comparable with those from southern europe e g monticchio in southern italy we conclude that the euganean hills were one of the northernmost refugial areas of temperate taxa in europe however the relative and absolute abundances of pollen of temperate trees are highly variable pollen inferred declines of temperate tree communities e g quercetum mixtum and low ostracod inferred water levels at lago della costa correspond to the cold heinrich events h 2 lgm 23 000 19 000 cal bp and h 3 around 28 000 cal bp as recorded in the marine sediments of the north atlantic similar patterns of significant temperate tree population collapses during cold heinrich events are recorded at southern mediterranean sites e g monticchio and the alboran sea these findings suggest close linkages between northern atlantic and south central european climates during the past glacial

migration and population expansion of abies fagus picea and quercus since 15000 years in and across the alps based on pollen percentage threshold values aims the aim of this study is to explore the migration colonization of new areas and subsequent population expansion within an area since 15 ka cal bp of abies fagus picea and quercus into and through the alps solely on the basis of high quality pollen data methods chronologies of 101 pollen sequences are improved or created data from the area delimited by 45 5 48 1 n and 6 14 e are summarized in three ways 1 in a selection of pollen percentage threshold maps thresholds 0 5 1 2 4 8 16 and 32 of land pollen 2 in graphic summaries of 250 year time slices and geographic segments lengthwise and transverse in relation to the main axis of the alps as pollen percentage curves pollen percentage difference curves and pollen percentage threshold ages cal bp graphed against both the length and the transverse alpine axes and 3 in tables showing statistical relationships of either pollen percentage threshold ages cal bp or pollen expansion durations time lapse between different pollen percentage threshold ages cal bp with latitude longitude and elevation to establish these relationships we used both simple linear regression and multiple linear regression after stepwise forward selection results the statistical results indicate that a the use of pollen percentage thresholds between 0 5 and 8 yield mostly similar directions of tree migration so the method is fairly robust b abies migrated northward fagus southward picea westward and quercus northward more detail does not emerge due to an extreme scarcity of high quality data especially along the southern foothills of the alps and in the eastern alps this scarcity allows the reconstruction of one immigration route only of abies into the southern alps the speed of population expansion following arrival of abies increased and of picea decreased during the holocene of fagus it decreased especially during the later holocene and of quercus it increased especially at the start of the holocene

late holocene evolution of the southwestern donana national park guadalquivir estuary sw spain a multivariate approach four phases are distinguished in the late holocene evolution of the southwestern donana national park sw spain based on a multidisciplinary analysis of the sediments present in drill cores in the oldest phase 2400 2500 cal yr bp a coastal lagoon the roman lacus ligustinus was recognized in the central part of this area partly closed by the donana spit and limited by fluvial levees the following phase 2400 2200 cal yr bp is characterized by high energy events which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the third phase 2200 2050 cal yr bp this new outlet was closed coinciding with the progradation of the donana spit the last phase 2050 cal yr bp recent comprises three periods a an unstable period 2050 1950 cal yr bp with the deposit of cheniers over the previous levees b an infilling period with a diminution of the marine influence and c the appearance of temporary ponds between the emerged levees and cheniers

environmental response to climatic and volcanic events in central europe during the weichselian lateglacial this paper reviews major results of the recent german research priority program changes of the geo biosphere during the last 15 000 years a contribution to pages focussing on changes of the geo biosphere during the weichselian lateglacial different continental archives such as annually laminated lacustrine sediments floodplain sediments and speleothems were used to reconstruct environmental response to climatic changes and the laacher see eruption event at ca 12 900 cal bp special emphasis is paid to establish a reliable time control using varve counting high precision radiocarbon dating of tree ring series and ams radiocarbon dating of terrestrial plant macrofossils recovered from lacustrine sediments to correlate and synchronize large scale environmental changes and events in central europe

detecting major terrain parameters relating to mass movements occurrence using gis remote sensing and statistical correlations case study lebanon abstract among the various natural hazards mass movements mm are probably the most damaging to the natural and human environment in mediterranean countries including lebanon which represents a good case study this research deals with how to use geographic information systems gis for establishing the relationships between mm occurrence and different factor terrain parameters over a representative region of lebanon parameters expressed by 1 ancillary data like lithology proximity to fault zone soil type land cover use distance to drainage line and rainfall quantity and 2 derived data like slope gradient and slope aspect were correlated with mm using gis approaches the mm were first detected through visual interpretation of two stereo pairs of spot 4 images anaglyph at 10 m resolution this study indicates depending on bivariate remote sensing and gis statistical correlations kendall tau b correlation that the lithology is the most influencing factor on mm occurrence it also shows that statistical correlations to mass movements exist best between factors at the following decreasing order of importance lithology proximity to fault line lithology soil type and lithology distance to drainage line at 1 level of significance and soil land cover use slope aspect land cover use and soil slope gradient at 5 level of significance these correlations were verified and checked through field observations and explained using univariate statistical correlations therefore they could be extrapolated to other mediterranean countries having similar geoenvironmental conditions

pollen and oxygen isotope analyses on late and post glacial sediments of the tourbiere de chirens dauphine france the sequence of vegetation phases in the late glacial was studied in a sediment section from the bog tourbiere de chirens by means of pollen analysis 18o16o ratios of samples of lacustrine marl obtained from the same profile reflect variations of 18o16o in precipitation and thus provide an additional independent paleoclimatic record the observed 18o16o variations agree well with the climatic history as deduced from pollen analysis the climatic transition from the oldest dryas to the bolling period sensu lato as well as the beginning and end of the younger dryas cold phase is marked by abrupt changes in the 18o16o ratio which were observed also in other regions of the alps these drastic climatic changes probably took place simultaneously over large areas of central europe and occurred within short time spans

incorporation of a physically based melt pond scheme into the sea ice component of a climate model the extent and thickness of the arctic sea ice cover has decreased dramatically in the past few decades with minima in sea ice extent in september 2005 and 2007 these minima have not been predicted in the ipcc ar4 report suggesting that the sea ice component of climate models should more realistically represent the processes controlling the sea ice mass balance one of the processes poorly represented in sea ice models is the formation and evolution of melt ponds melt ponds accumulate on the surface of sea ice from snow and sea ice melt and their presence reduces the albedo of the ice cover leading to further melt toward the end of the melt season melt ponds cover up to 50 of the sea ice surface we have developed a melt pond evolution theory here we have incorporated this melt pond theory into the los alamos cice sea ice model which has required us to include the refreezing of melt ponds we present results showing that the presence or otherwise of a representation of melt ponds has a significant effect on the predicted sea ice thickness and extent we also present a sensitivity study to uncertainty in the sea ice permeability number of thickness categories in the model representation meltwater redistribution scheme and pond albedo we conclude with a recommendation that our melt pond scheme is included in sea ice models and the number of thickness categories should be increased and concentrated at lower thicknesses

lateglacial and early flandrian coleoptera from la taphanel massif central france climatic and ecological implications a lateglacial and early holocene sequence of coleopteran assemblages is described from la taphanel in the massif central france the site is a sediment filled small lake at an altitude of almost 1000 m the insect fauna provides evidence for a detailed palaeoecological reconstruction and in particular enables a reconstruction of climatic changes at the close of the last glaciation a sudden climatic warming occurs at about 13000 yr bp followed by a temperate episode equivalent in time to the bolling period there is clear evidence of a short cold period between the bolling and allerod that is approximately equivalent to the older dryas period the allerod phase is decidedly cooler than the bolling as is shown by the coleoptera from several sites in northwest europe a clear younger dryas signal is provided by the coleoptera with climates similar in severity to those of the glacial period the climatic improvement at the start of the holocene is also sudden so that by preboreal times temperatures were equivalent to those of the present day

late glacial climatic oscillations as recorded in swiss lake sediments regional pollen assemblage zones for the late glacial period of the swiss plateau are introduced and defined they include four major zones artemisia juniperus hippophae betula pinus paz with several subzones pollen and oxygen isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000 9500 yr bp the first oscillation termed the aegelsee fluctuation occurs shortly before 12 000 yr bp and varve counts suggest its duration was ca 100 yr it is characterised by a short decrease in the oxygen isotopes as well as a short increase in nap associated with a depression in birch pollen values the second oscillation which occurs in the 18o record shortly before the deposition of the laacher see tephra ca 11 000 yr bp is termed the gerzensee fluctuation it occurs during a pine dominated phase and its vegetational effects cannot be determined palynologically the most prominent regressive phase is the younger dryas biozone ca 10 700 10 000 yr bp characterised by an increase in heliophilous nap and low 18o values the younger dryas biozone can often be subdivided palynologically into two parts a first part rich in grasses and juniper and a second part with higher filipendula and birch values during the preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios comparison of the swiss oxygen isotope profiles with the greenland dye 3 record suggests that not only the three major shifts in the 18o curves but also the minor ones are closely comparable suggesting some common climatic control

comparison of different retrieval techniques for melt ponds on arctic sea ice from landsat and modis satellite data melt ponds are regularly observed on the surface of arctic sea ice in late spring and summer they strongly reduce the surface albedo and accelerate the decay of actic sea ice until now only a few studies have looked at the spatial extent of melt ponds on arctic sea ice knowledge of the melt pond distribution on the entire arctic sea ice would provide a solid basis for the parameterization of melt ponds in existing sea ice models due to the different spectral properties of snow ice and water a multispectral sensor such as landsat 7 etm is generally applicable for the analysis of distribution an additional advantage of the etm sensor is the very high spatial resolution 30 m an algorithm based on a principal component analysis pca of two spectral channels has been developed in order to determine the melt pond fraction pca allows differentiation of melt ponds and other surface types such as snow ice or water spectral bands 1 and 4 with central wavelengths at 480 and 770 nm respectively are used as they represent the differences in the spectral albedo of melt ponds a landsat 7 etm scene from 19 july 2001 was analysed using pca the melt pond fraction determined by the pca method yields a different spatial distribution of the ponded areas from that developed by others a modis subset from the same date and area is also analysed the classification of modis data results in a higher melt pond fraction than both landsat classifications

radiocarbon calibration uncertainties during the last deglaciation insights from new floating tree ring chronologies abstract radiocarbon dating is the most commonly used chronological tool in archaeological and environmental sciences dealing with the past 50 000 years making the radiocarbon calibration curve one of the most important records in paleosciences for the past 12 560 years the radiocarbon calibration curve is constrained by high quality tree ring data prior to this however its uncertainties increase rapidly due to the absence of suitable tree ring 14c data here we present new high resolution 14c measurements from 3 floating tree ring chronologies from the last deglaciation by using combined information from the current radiocarbon calibration curve and ice core 10be records we are able to absolutely date these chronologies at high confidence we show that our data imply large 14c age variations during the bolling chronozone greenland interstadial 1e a period that is currently characterized by a long 14c age plateau in the most recent intcal13 calibration record we demonstrate that this lack of structure in intcal13 may currently lead to erroneous calibrated ages by up to 500 years

high resolution climate signals in the bolling allerod interstadial greenland interstadial 1 as reflected in european tree ring chronologies compared to marine varves and ice core records abstract lateglacial and holocene tree ring chronologies are unique archives which provide various information on past environments on a true annual time scale changes in ring width can be related to past climate anomalies and dendrodated wood provides an ideal source for radiocarbon calibration we present a 1051 year tree ring chronology from the late glacial built from subfossil scots pines pinus sylvestris that grew in different regions of central and southern europe through a series of high precision radiocarbon measurements we obtained a floating radiocarbon chronology which allowed accurate wiggle matching to the intcal98 calibration curve the trees show a coherent pattern in ring width variations throughout central europe and extending into the mediterranean which indicates a strong external climatic factor most probably temperature during the growing season we identified major growth events which appear synchronous with events seen in isotopic and tracer signals in the greenland ice cores and with changes in the strength of upwelling in the cariaco basin

automated classifications of topography from dems by an unsupervised nested means algorithm and a three part geometric signature abstract an iterative procedure that implements the classification of continuous topography as a problem in digital image processing automatically divides an area into categories of surface form three taxonomic criteria slope gradient local convexity and surface texture are calculated from a square grid digital elevation model dem the sequence of programmed operations combines twofold partitioned maps of the three variables converted to greyscale images using the mean of each variable as the dividing threshold to subdivide increasingly subtle topography grid cells sloping at less than mean gradient of the input dem are classified by designating mean values of successively lower sloping subsets of the study area nested means as taxonomic thresholds thereby increasing the number of output categories from the minimum 8 to 12 or 16 program output is exemplified by 16 topographic types for the world at 1 km spatial resolution srtm30 data the japanese islands at 270 m and part of hokkaido at 55 m because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre set criteria the resulting classes are undefined and must be calibrated empirically by subsequent analysis maps of the example classifications reflect physiographic regions geological structure and landform as well as slope materials and processes fine textured terrain categories tend to correlate with erosional topography or older surfaces coarse textured classes with areas of little dissection in japan the resulting classes approximate landform types mapped from airphoto analysis while in the americas they create map patterns resembling hammond s terrain types or surface form classes srtm30 output for the united states compares favorably with fenneman s physical divisions experiments are suggested for further developing the method the arc info aml and the map of terrain classes for the world are available as online downloads

a new late glacial to early holocene palaeobotanical and archaeological record in the eastern pre alps the palughetto basin cansiglio plateau italy a late glacial to early holocene lacustrine and peat succession rich in conifer remains and including some palaeolithic flint artefacts has been investigated in the palughetto intermorainic basin venetian pre alps the geomorphological and stratigraphical relationships 14c dates and pollen analyses allow a reconstruction of the environmental history of the basin and provide significant insights into the reforestation and peopling of the pre alps the onset of peat accumulation is dated to 14 4 14 1 kyr cal bp coinciding with reforestation at middle altitudes that immediately post dates the immigration of larix decidua and picea abies subsp europaea plant macrofossils point to the expansion of spruce about 14 3 kyr cal bp so far one of the earliest directly dated in the late glacial period of southern europe the previous hypothesis of an early holocene spruce immigration in the southern alps from slovenia needs reconsideration organic sedimentation stopped at the end of the younger dryas and was followed by the evolution of hydromorphic soils containing lithic artefacts anthropic structures and wood charcoal the typological features of the flint implements refer human occupation of the site to the end of the recent epigravettian charcoals yielded dates either consistent with or younger than the archaeological chronology in the early and middle holocene copyright 2000 john wiley sons ltd

shallow landslide susceptibility assessment in a semiarid environment a quaternary catchment of kwazulu natal south africa abstract this paper presents an evaluation of landslide susceptibility maps based on the frequency ratio fr landslide susceptibility index lsi logistic regression lr and artificial neural network ann methods applied within a quaternary catchment in the kwazulu natal region south africa landslide occurrence in this particular catchment is generally induced by heavy rainfall events where shallow landslips occur mostly on steep slopes thereby threatening informal housing at the base of slopes the scope of this study is to compare the performance of landslide susceptibility models and rate the importance of landslide causal factors thirteen landslide causal factors including altitude slope angle aspect slope total curvature slope plan curvature slope profile curvature proximity to stream network topographic wetness index twi lithology land cover proximity to faults proximity to dolerite sills and dykes and proximity to the road network were considered in the study furthermore each causal factor was rated according to the above mentioned methods and it was found that the most influential landslide causal factors are the altitude land cover and lithology the resulting susceptibility maps were classified into 5 classes ranging from very low to very high susceptibility model performance was tested using an independent validation set comprising 10 of all mapped landslides for verification of the models performance receiver operating curves rocs were calculated and the areas under curve auc for the success rate curves were 0 736 0 748 0 827 and 0 809 for fr lsi lr and ann respectively the findings revealed that models showed promising results for shallow landslide susceptibility modelling since they all give accuracy values higher than 73 the lr and ann methods however proved to be superior in representing landslide susceptibility throughout the study area

the abrupt termination of the younger dryas climate event previous studies on two deep greenland ice cores have shown that a long series of climate oscillations characterized the late weichselian glaciation in the north atlantic region1 and that the last glacial cold period the younger dryas ended abruptly 10 700 years ago2 here we further focus on this epoch defining event and present detailed heavy isotope and dust concentration profiles which suggest that in less than 20 years the climate in the north atlantic region turned into a milder and less stormy regime as a consequence of a rapid retreat of the sea ice cover a warming of 7 c in south greenland was completed in about 50 years

sensitivity and response time of natural systems to climatic change in the late quaternary abstract although the leading theory for the cause of climatic change the milankovitch perturbations in insolation indicates variable rates of change at different latitudes any discussion of the sensitivity and response time of different natural systems is most practical when the climatic change is considered to be relatively abrupt and global rather than gradual and regional the oxygen isotope record in glacial ice should have the swiftest response time but the stratigraphic record in ice sheets at particular localities may be obscured or confused if the glacier flow is irregular the oxygen isotope stratigraphy of ocean sediment cores is a sensitive reflection primarily of contemporaneous ice volume and to a lesser extent ocean temperature ocean temperature however is recorded more specifically by microfossils in ocean sediments and may reflect global insolation directly except that in the north atlantic the influence of glacial meltwater and various feedbacks may override the insolation factor the differential lags in the response of isotopes and faunas to insolational change are apparent in the ocean sediment stratigraphy ice sheets themselves at their terminus may respond to climatic change only slowly if a change in snow accumulation is the factor because of the time involved in building a thickness sufficient for flow to great distances but if wastage near the margin is the factor then the response may be more rapid some glaciers however may advance rapidly without regard to climatic change as in the case of surging or they may retreat just as rapidly if they terminate in deep water through iceberg formation world sea level is depressed with glacial growth and thus reflects the volume of ice sheets but isostatic changes in the crust complicate the sea level response not only locally beneath the ice load but elsewhere as well the pluvial lakes of the american southwest correlated in their high levels with intervals of glaciation show a direct response to climatic patterns resulting from the expansion of the north american ice sheets and thus may lag with respect to the primary climatic change that causes ice sheet growth north african lakes on the other hand respond to the intensity of monsoonal circulation which is controlled directly by insolational shifts the response of plants and insects to deglaciation can be immediate in the case of pioneers on newly exposed terrain although the deglaciation itself may lag behind climatic change succession can follow rapidly but then more slowly as other plants immigrate from great distances it is heare where the more realistic assumption of continuing climatic change may be necessary to explain the dynamics of long range vegetational change following the last deglaciation the distribution and abundance of vertebrate populations reflect primarily their food resources and the disharmonious faunas of the last glacial period in north america with components that no longer have overlapping ranges perhaps may be explained by vegetational associations that likewise may have no modern analogues the cause may be a different climatic seasonality wastage of the ice sheet itself lagging behind the climatic change may have changed the seasonal climatic patterns sufficiently to bring about the precipitous extinction of many vertebrate species

rates of change and chronological problems during the late glacial period results of high resolution ams 14c dating of terrestrial plant macrofossils from late glacial and early holocene lake deposits in switzerland show three periods with constant radiocarbon ages these plateaux of constant age occur at 12700 10000 and 9500 y bp a comparison of this radiocarbon chronology with a varve chronology documents discrepancies between the sidereal and the radiocarbon time scale for the late glacial period the age plateaux and the time scale discrepancies have a significant impact on the estimation of rates of change during this period estimates of rates of change can be very misleading if calculated on the basis of radiocarbon ages this is illustrated by an example of estimated rates of late glacial and early holocene palynological change in switzerland

disposition of solar radiation in sea ice and the upper ocean a one dimensional sea ice model with an ice thickness distribution is presented to examine the disposition of the incoming surface shortwave radiation within the sea ice and the upper ocean the sea ice model consists of 15 different ice thickness categories and an open water leads category ice growth melting on horizontal and vertical surfaces meltwater pond growth and drainage and snow accumulation evolve independently for each of the ice categories leads melt ponds and thinner ice categories are of particular interest as these features account for nearly all of the solar energy that is transmitted into the upper ocean beneath the ice pack also examined is the surface reflection and absorption internal ice absorption and lateral melting for ponded and pond free ice area averaged results show that 69 of the total annual solar energy is reflected 15 is absorbed by the snow cover 12 is absorbed by the ice and 4 is transmitted to the ocean mixed layer through thin ice and leads

columbia mountain landslide late glacial emplacement and indications of future failure northwestern montana usa abstract the well preserved and undissected columbia mountain landslide which is undergoing suburban development was studied to estimate the timing and processes of emplacement the landslide moved westward from a bedrock interfluve of the northern swan range in montana usa onto the deglaciated floor of the flathead valley the landslide covers an area of about 2 km2 has a toe to crown height of 1100 m a total length of 3430 m a thickness of between 3 and 75 m and an approximate volume of 40 million m3 deposits and landforms define three portions of the landslide from the toe to the head they are i clast rich diamictons made up of gravel sized angular rock fragments with arcuate transverse ridges at the surface ii silty and sandy deposits resting on diamictons in an internally drained depression behind the ridges and iii diamictons containing angular and subangular pebble to block sized clasts some of which are glacially striated in an area of lumpy topography between the depression and the head of the landslide drilling data suggest the diamictons cover block to slab sized bedrock clasts that resulted from an initial stage of the failure the landslide moved along a surface that developed at a high angle to the ne dipping thinly bedded metasediments of the proterozoic belt supergroup the exposed slope of the main scarp dips 30 37 w a hypothetical initial rotational failure of the lower part of a bedrock interfluve may have transported bedrock clasts into the valley the morphology and deposits at the surface of the landslide indicate deposition by a rock avalanche sturzstrom derived from a second stage of failure along the upper part of the scarp the toe of the columbia mountain landslide is convex west in planview except where it was deflected around areas now occupied by glacial kettles on the north and south margins landsliding therefore occurred during deglaciation of the valley while ice still filled the present day kettles available chronostratigraphy suggests that the 1 km thick glacier in the region melted before 12 000 14c years bp within 3000 years of the last glacial maximum deglaciation and hillslope failure are likely causally linked failure of the faceted interfluve was likely due tensile fracturing of bedrock along a bedding normal joint set shortly after glacial retreat from the hillslope open surficial tension fractures and grabens in the swan range are limited to an area above the crown of the landslide movement across these features suggests that extensional flow of bedrock sackung is occurring in what remains of the ridge that failed in the columbia mountain landslide the fractures and grabens likely were initiated during failure but their morphologies suggest active extension across some grabens continued movement of bedrock above the crown may result in future mass movements from above the previous landslide scarp landslides sourced from bedrock above the scarp of the late glacial columbia mountain landslide which could potentially be triggered by earthquakes are geologic hazards in the region

impact of melt ponds on arctic sea ice simulations from 1990 to 2007 1 the extent and thickness of the arctic sea ice cover has decreased dramatically in the past few decades with minima in sea ice extent in september 2007 and 2011 and climate models did not predict this decline one of the processes poorly represented in sea ice models is the formation and evolution of melt ponds melt ponds form on arctic sea ice during the melting season and their presence affects the heat and mass balances of the ice cover mainly by decreasing the value of the surface albedo by up to 20 we have developed a melt pond model suitable for forecasting the presence of melt ponds based on sea ice conditions this model has been incorporated into the los alamos cice sea ice model the sea ice component of several ipcc climate models simulations for the period 1990 to 2007 are in good agreement with observed ice concentration in comparison to simulations without ponds the september ice volume is nearly 40 lower sensitivity studies within the range of uncertainty reveal that of the parameters pertinent to the present melt pond parameterization and for our prescribed atmospheric and oceanic forcing variations of optical properties and the amount of snowfall have the strongest impact on sea ice extent and volume we conclude that melt ponds will play an increasingly important role in the melting of the arctic ice cover and their incorporation in the sea ice component of global circulation models is essential for accurate future sea ice forecasts

allerod younger dryas lake temperatures from midge fossils in atlantic canada remains of freshwater midges are abundant in lake sediments and their species distributions are closely related to the surface water temperature of lakes their distributions thus provide a powerful tool for paleoclimatology the distribution of species in a core from splan pond in atlantic canada indicates that there were abrupt transitions in late glacial temperatures between warm and cold states the transitions are correlative with the well known warm allerod and cold younger dryas events in europe these data thus confirm the inference from palynological data that these events affected regions on both sides of the atlantic

evidence of recent surface faulting and surface rupture in the fore alps of veneto and trentino ne italy abstract the fore alps of western veneto and trentino regions belong to the central southern alps ne italy in which there is little evidence of very fresh surface ruptures or surface faulting this does not seem to match historical data about earthquakes some of which have been very intense the strong influence of the inherited structures makes it difficult to detect a direct link between morphotectonic features and present day stress fields in the present study four areas orsara scandole naole and soran with surface faulting and surface rupture features were examined and models of morphotectonic evolution are discussed in the lessini mountains the orsara graben and scandole ridge show examples of surface faulting and surface rupture respectively reactivating paleogene normal faults and fractures within the orsara graben rocky bluffs displace the previous morphological features the bluffs are some decimetres to some metres high and are practically devoid of evidence of either physical or chemical weathering on the slopes above them are steep areas which may be interpreted as the remnants of previous strongly weathered bluffs the scandole ridge has many trenches some with rocky walls which may be the result of several episodes of morphotectonic rupture in the giudicarie belt the naole and mt soran surface faulting landforms are details within large frontal culmination walls of neogene thrusts the naole ridge corresponds to the southeastern sector of monte baldo here inside a fault angle valley a sinuous scarp originating from surface faulting marks the base of the fault scarp slope ridge splitting is the expression of the backward migration of separation niches due to slope tectonics also evidenced on the slope by several terrace like features and by a lower belt of very thick slope breccias on mt soran in the gruppo di brenta massif the surface faulting scarp faces uphill giving rise to a trench like feature downvalley of the scarp there is the niche of a large landslide dated to 3 kyears b p all these landforms are consistent with slope tectonic movements caused by intense earthquakes whereas the morphostructures in the lessini mountains are the result of responses by sensitive structures the naole and mt soran features express the evolution of frontal culmination walls of thrusts with clear evidence of present day tectonic activity on the basis of the weathering of the scarps and associated features the relative seismotectonic episodes probably occurred between the bronze and middle ages

use of uranium thorium dating to determine past 14c reservoir effects in lakes examples from antarctica the chronologies of many lacustrine records suffer from radiocarbon reservoir effects due to the presence of dissolved dead carbon or to slow air water exchange here we use the tims uranium thorium disequilibrium method in conjunction with ams radiocarbon dating to determine the age of lacustrine carbonates and to quantify the past radiocarbon reservoir effect in two antarctic lakes with differing characteristics by correcting a single sample u th age for detrital contamination a 14 c offset of v18 000 yr was obtained for carbonates from the former grounding line of the ross sea ice sheet in glacial lake trowbridge this large reservoir effect is believed to result from the direct input of old co2 from glacial meltwater in the second example an isochron approach on coeval samples formed at the bottom of lake vida now exposed due to lower lake level yielded an age of 9550 340 yr b p and a radiocarbon reservoir age of 3600 yr this offset was probably the result of lack of aeration due to perennial ice cover and or strong density stratification this evidence for long term isolation of the lake bottom indicates another level of hardship for life in the dry valley lacustrine environment an environment studied as an analogue for extreme periods of earth history as well as for exobiological implications the success of the u th technique on these two examples indicates that tims u th dating will be of widespread use in dating the important climate information recorded in the dry valleys both within and beyond the 14 c age range fl 2001 elsevier science b v all rights reserved

physical characteristics of summer sea ice across the arctic ocean sea ice characteristics were investigated during july and august on the 1994 transect across the arctic ocean properties examined from ice cores included salinity temperature and ice structure salinities measured near zero at the surface increasing to 3 4 at the ice water interface ice crystal texture was dominated by columnar ice comprising 90 of the ice sampled surface albedos of various ice types measured with radiometers showed integrated shortwave albedos of 0 1 to 0 3 for melt ponds 0 5 for bare discolored ice and 0 6 to 0 8 for a deteriorated surface or snow covered ice aerial photography was utilized to document the distribution of open melt ponds which decreased from 12 coverage of the ice surface in late july at 76 n to almost none in mid august at 88 n most melt ponds were shallow and depth bore no relationship to size sediment was pervasive from the southern chukchi sea to the north pole occurring in bands or patches it was absent in the eurasian arctic where it had been observed on earlier expeditions calculations of reverse trajectories of the sediment bearing floes suggest that the southernmost sediment was entrained during ice formation in the beaufort sea while more northerly samples probably originated in the east siberian sea some as far west as the new siberian islands

modeling the summertime evolution of sea ice melt ponds 1 we present a mathematical model describing the summer melting of sea ice we simulate the evolution of melt ponds and determine area coverage and total surface ablation the model predictions are tested for sensitivity to the melt rate of unponded ice enhanced melt rate beneath the melt ponds vertical seepage and horizontal permeability the model is initialized with surface topographies derived from laser altimetry corresponding to first year sea ice and multiyear sea ice we predict that there are large differences in the depth of melt ponds and the area of coverage between the two types of ice we also find that the vertical seepage rate and the melt rate of unponded ice are important in determining the total surface ablation and area covered by melt ponds

landslides as a geomorphological proxy for climate change a record from the dolomites northern italy abstract this study investigates the relationships between climate changes and hillslope evolution in the dolomites eastern alps italy during the late quaternary with particular attention paid to landslide processes the basic premise is that modifications in landslide frequency may be interpreted as changes in the hydrological conditions of slopes which are in turn controlled by climate after the statistical analysis of a data set composed of 73 conventional radiocarbon ages obtained from 24 landslides four periods of enhanced landsliding have been identified i from 10 700 to 8400 cal bp between younger dryas and the preboreal ii from 8200 to 6900 cal bp during the older atlantic iii from 5800 to 4500 cal bp between atlantic and subboreal and iv from 4000 to 2100 cal bp between subboreal and subatlantic these periods have been compared with different lateglacial and holocene paleoclimatic records to check the correspondence between periods of enhanced landslide activity and cold and humid spells recognized at different spatial scales as the records show in the study areas slope instability processes can be considered geomorphological indicators of climatic changes and to a certain extent reliable proxies of environmental evolution

tectonic conditioning revealed by seismic refraction facilitates deep seated landslides in the western escarpment of the main ethiopian rift abstract landslide is a geo hazard phenomenon that has been taking lives and causing severe property damages all over the world mostly in mountainous areas the main ethiopian rift has a unique tectonic setting with complex geological and geomorphological features coupled with continuously deteriorating environmental conditions which made its escarpments vulnerable for landslides the study area is located near the debre sina town within the yizaba wein locality which has been severely affected by frequent landslide problems this work was carried out using a multidisciplinary approach based on geological geomorphological kinematic analysis and geophysical survey seismic refraction investigations were carried out along the yizaba wein landslide main scarp to determine the depth to the bedrock and to the failure plane to assess the stability of the slope to locate possible structural features and to identify the extent of recent landslide activity and to study the subsurface situation the seismic measurements were made along three nearly orthogonal survey lines in the recently affected area a high resolution 2d p wave survey was conducted using a 24 channel seismic unit the seismic refraction results revealed four layers of geomaterials with distinct physical characteristics that contained a subsurface landslide anomaly within the layers the layers were interpreted according to the major lithological units from top to bottom i clay loosely cemented colluvial sediments and highly weathered agglomeratic basalt ii highly to moderately fractured porphyritic basalt ignimbrite volcanic ash and rhyolite trachyte iii moderately to slightly fractured ignimbrite rhyolite trachyte and basalt and iv very strong massive fresh rock bedrock faults and weak zones have also been identified in the bedrock based on the abundance of fractures and subsidiary faults resulting from damage of rocks and change of lithology due to variable fault rock formation strongly influencing the wavefield distribution which usually causes a local decrease of the velocity value the main findings show that the landslide in the yizaba wein locality was caused by its complex geological structural setting and downslope movement of the underlying pyroclastic sediment facilitated by heavy rainfall considering the similar geological and tectonic settings similar mechanisms can be assumed for other landslides along the rift margins and associated highlands of ethiopia

high resolution late glacial chronology for the gerzensee lake record switzerland δ18o correlation between a gerzensee stack and ngrip oxygen isotope variations were analyzed on bulk samples of shallow water lake marl from gerzensee switzerland in order to evaluate major and minor climatic oscillations during the late glacial to highlight the overall signature of the gerzensee 18o record 18o records of four parallel sediment cores were first correlated by synchronizing major isotope shifts and pollen abundances then the records were stacked with a weighting depending on the differing sampling resolution to develop a precise chronology the 18o stack was then correlated with the ngrip 18o record applying a monte carlo simulation relying on the assumption that the shifts in 18o were climate driven and synchronous in both archives the established chronology on the gicc05 time scale is the basis for 1 comparing the 18o changes recorded in gerzensee with observed climatic and environmental fluctuations over the whole north atlantic region and 2 comparing sedimentological and biological changes during the rapid warming with smaller climatic variations during the bolling allerod period the 18o record of gerzensee is characterized by two major isotope shifts at the onset and at the termination of the bolling allerod warm period as well as four intervening negative shifts labeled gi 1e2 d c2 and b which show a shift of one third to one fourth of the major 18o shifts at the beginning and end of the bolling allerod despite some inconsistency in terminology these oscillations can be observed in various climatic proxies over wide regions in the north atlantic region especially in reconstructed colder temperatures and they seem to be caused by hemispheric climatic variations

vegetation and climate during the weichselian early glacial and pleniglacial in the niederlausitz eastern germany macrofossil and pollen evidence cryoturbated organic beds and channel fills intercalated with sandy and gravelly fluvial units have been studied in an opencast brown coal mine near nochten niederlausitz eastern germany the fluvial aeolian sequence covers parts of the early pleni and late glacial the detailed chronology is based on 11 radiocarbon and 12 osl dates covering the period between ca 100 kyr and 11 kyr bp basal peat deposits are correlated with an early weichselian interstadial during this period boreal forests were present and minimum mean summer temperatures were 13 c early pleniglacial deposits are absent the middle and late pleniglacial environments were treeless and different types of tundra vegetation can be recognised minimum mean summer temperatures varied between 10 and 15 c vegetation and climate is reconstructed in detail for the periods around 34 38 kyr bp and 24 25 kyr bp around 34 38 ka a mixture between a low shrub tundra and a cottongrass tussock subshrub tundra was present the botanical and sedimentological data suggest that from the middle to the late pleniglacial the climate became more continental aridity and wind strength increased and the role of a protecting winter snow cover decreased a sedge grass moss tundra dominated around 24 and 25 kyr bp copyright 2001 john wiley sons ltd

a stable isotope tree ring timescale of the late glacial holocene boundary late glacial and holocene tree ring chronologies like deep sea sediments or polar ice cores contain information about past environments changes in tree ring growth rates can be related to past climate anomalies and changes in the isotope composition of tree ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere we have established a 9 928 year absolutely dated dendrochronological record of holocene oak quercus robur quercus petraea and a 1 604 year floating late glacial and early holocene chronology of pine pinus sylvestris from subfossil tree remnants deposited in alluvial terraces of south central european rivers the pine sequence provides records of dendro dated 14c 13c and 2h patterns for the late younger dryas and the entire preboreal 10 100 9 000 yr bp through the use of dendrochronology radiocarbon age calibration and stable isotope analysis we suggest that the late glacial holocene transition may be identified and dated by 13c and 2h tree ring chronologies

late and post glacial evolution of lake steisslingen i abstract piston cores from lake steisslingen a small hard water lake situated 20 km west of lake constance and mainly supplied by submerged springs reveal a record of the environmental history going back to 15 600 cal yr bp from the bolling to ca 9800 cal yr bp the sediments are partly seasonally laminated from then on up to the middle ages the lamination is mostly undisturbed providing a high resolution time scale by varve counting a detailed pollen profile and 13 ams 14c analyses all investigated sediment sections show evidence of exceptionally high sulphate concentrations in the lake water which lead to the fixation of all reactive iron as pyrite the high sulphur content can only be attributed to s rich water supplied by the submerged springs thus indicating the miocene obere meeres molasse as the dominant aquifer since soil erosion is strongly reduced due to increased forest density in the preboreal boreal the submerged springs are the main nutrient source for the lake mixing or stable stratification of the waterbody mostly depends on nutrient availability and bioproductivity in the epilimnion the controlling external factors are wind and changes in water level and or temperature at the end of the younger dryas and during the preboreal low water levels and precipitation rates are assumed the water column mixing was regular bioproductivity high and high degradation activity of organic matter led to a redissolution of calcite the hydrological separation of a northern shallow lake seeried probably fell into the period of this low lake level around 10 450 10 300 cal yr bp the lake level rose but never again reached the former level between 10 000 and 7200 cal yr bp non glacial varves are even found in shallower parts of the lake indicating a stable anoxic monimolimnion with a rising chemocline bioproductivity was low wind protection provided by the now dense forestation and favourable climatic conditions e g high summer temperatures and low winter temperatures seem to be the responsible factors fluctuating human impact is identified from about 7400 cal yr bp until permanent settlement by the alemanni about 1500 cal yr bp strong human influence is observed from 2000 cal yr bp onwards when agricultural activity and clearing of the shoreline vegetation by man caused high soil erosion rates and thus eutrophication at about 800 cal yr bp the recent hydrological conditions were established by implementing an artificial drain thus lowering the lake level

laacher see tephra a widespread isochronous late quaternary tephra layer in central and northern europe a late quaternary tephra layer widespread in central and northern europe resulted from explosive plinian and phreatomagmatic eruptions of the laacher see volcano 11 000 yr b p the tephra is distinguished from other late quaternary andesitic rhyolitic airfall tuff layers in northern europe and from basaltic or trachytic tuff deposits in southern europe by its phonolitic composition and abundance of sanidine plagioclase clinopyroxene amphibole and sphene the proximal tephia sequence at laacher see is divided into three main deposits the predominantly plinian deposits of lower and middle laacher see tephra llst and mlst and phreatomagmatic deposits of the upper laacher see tephra ulst the mlst member is further subdivided into beds a b and c1 c2 and c3 the chemical composition of the magma is highly differentiated phonolite in the llst to mlst b sections but mafic phonolite in the mlst c1 to ulst sections all deposits are considered to be isochronous the frequency maximum of 16 radiocarbon datings indicating an eruption about 11 000 50 yr b p distal ash was deposited in three main fans directed to the northeast lst traced up to 1 100 km distance south lst traced up to 600 km and southwest lst traced up to 100 km tephrostratigraphic correlation of the distal ash deposits is based on a the major element composition of glass shards b lithology and c heavy mineral analyses the northeastern fan consists of deposits from llst mlst b and mlst c1 eruptive phases the southern fan comprises mlst a mlst c2 and ulst deposits and the southwestern fan consists exclusively of ash from the ulst eruptive phase northeastern transport of ash during eruptive phases with high plinian eruption columns but southern and southwestern transport of ash along phases of relatively low eruption columns are interpreted in terms of prevailing southwesterly paleowinds at high altitudes tropopause level but northerly winds dominating in the lower atmosphere the laacher see eruption columns were emplaced into an atmosphere vertically zoned with respect to paleowind directions which also explains the near vent shifting of llst mlst b and mlst c1 iso pach axes from east southeast to northeast within the first 20 km of transport

geomorphons landform and property predictions in a glacial moraine in indiana landscapes abstract predicting soil property distribution from a catena in the digital environment has been explored by many researchers with only slightly better than modest results in this study the landform recognition algorithm geomorphons in the grass gis environment was explored to determine if this landscape model could improve predictions of soil properties for 74 borings on the wabash glacial moraine in wells county indiana measurements were made for a horizon thickness depth to chroma 2 features effervescence dense glacial till carbonate concretions and autochthonous platy structure a digital elevation model dem generated from light detection and ranging lidar data was used for the study site the geomorphons algorithm was used to generate 10 original landforms flat footslope summit ridge shoulder spur slope hollow valley and depression that were aggregated to new landforms coinciding with slope positions toeslope footslope backslope shoulder summit and depression recognized by soil surveyors linear discriminant analysis lda and multinomial logistics regression analysis mlr were used to aggregate the measured soil properties into the landform groups the aggregation of geomorphons groups improved the mrl predictions to 83 accuracy also the aggregation of geomorphons to five landforms to predict soil property distribution on the landscape gave promising results for the low relief and relatively flat area of northeast indiana to test if the true mean value of each soil property for each landform was reliable for generalizing population characteristics relative standard error rse was calculated as a proportion of standard error to population mean from a bootstrap estimation the range of rse values for all soil properties and landforms was between 0 7 and 19 since the estimates of the measured soil properties all have rse values of less than 25 they can be considered reliable

sudden changes in north atlantic circulation during the last deglaciation sudden changes in the flow of warm atlantic surface waters into the norwegian sea occurred frequently during the last deglaciation typically involving shifts in sea surface temperature of 5 c in fewer than 40 years these led to equally large and rapid changes in atmospheric temperatures and to shifts in atlantic deep thermo haline circulation and ice sheet melting rates

landform pattern recognition and classification for predicting soil types of the uasin gishu plateau kenya abstract information obtained from landform classification is fundamental for understanding physical chemical and biological soil processes digital elevation models dems can be used for landform classification using a geomorphic pattern recognition and classification approach such as geomorphons in this study we used geomorphons to predict soil types of the uasin gishu plateau in western kenya with the aim of improving the existing soil type maps we ran the geomorphons classification on the 30 m shuttle radar topographic mission srtm dem using the module r geomorphons add on in grass gis with look up distance l values of 10 20 30 40 50 60 70 80 90 and 100 cells 300 m to 3 000 m and flatness threshold values of 2 0 5 and 0 01 degrees we grouped the resulting geomorphons into three classes upland summits upland midslopes and bottomlands we then assigned soil types according to the world reference base soil classification system to these three landscape positions after dividing the study area into the lower plateau and the upper plateau based on elevation and geomorphology the predicted soil types were quantitatively evaluated against 50 soil point observations based on overall accuracy precision recall and cohen s kappa coefficient k metrics evaluation results showed that an l value of 20 cells performed best k 0 52 overall accuracy 0 62 followed by an l value of 30 cells k 0 50 overall accuracy 0 58 l values of 60 70 and 80 cells performed worse k 0 35 overall accuracy 0 48 although an l value of 20 cells performed slightly better than an l value of 30 cells the l value of 30 cells better captured the geomorphology and soil landscape relationships based on our own expert knowledge legacy data and the fact that the bottomlands pattern was more continuous for an l value of 30 cells than for an l value of 20 cells upland summits occurred over 32 of the plateau and were occupied by nitisols on the upper plateau and ferralsols on the lower plateau upland midslopes occurred over 42 of the plateau and were occupied by acrisols on the upper plateau and acrisols ferralsols on the lower plateau bottomlands occurred over 26 of the plateau and were occupied by luvisols gleysols on both the upper and lower plateau geomorphons as a method of landform classification correlated to geomorpho pedological processes and captured soil variations and differences in the study area the approach is computationally efficient and can be used for large areas but is limited in that it only classifies landscapes according to shape this means that the algorithm does not separate or identify soil types with different parent materials occurring within one landform class thus regosols and cambisols on very steep slopes and acrisols and ferralsols on gentle slopes could not be separated

the role of shortwave radiation in the summer decay of a sea ice cover heat balance models of ice leads and the underlying water column were used to investigate the role of shortwave radiation in the summer decay of a sea ice cover because of the potential importance of positive feedback between decreasing ice concentration and increasing solar input to the ocean particular emphasis was given to the treatment of heat transfer and lateral melting in leads the rate of heat loss to floe edges was calculated from lead temperatures using an empirical boundary layer parameterization coefficients for this parameterization were obtained from field measurements in the dynamically active ice cover of the greenland sea during the 1984 marginal ice zone experiment and in the static ice of mould bay northwest territories field coefficients were found to be considerably larger than those previously obtained in the laboratory suggesting that heat transfer rates near floe edges were controlled more by winds and currents than by local density differences model studies of individual leads indicate that heat losses to the atmosphere cause lateral melt rates to asymptotically approach a constant value as lead size increases thus although very wide leads transmit considerable energy to the underlying ocean they have relatively little effect on lateral melting other results provide information on the relative importance of horizontal heat transfer rates ice thickness floe perimeter atmospheric forcing and oceanic heat flux in general the calculations indicate that much of the shortwave radiation entering the ocean is absorbed below the ice where it contributes to bottom ablation rather than lateral melting this suggests that previous work has seriously overestimated the magnitude of the feedback between ice concentration and incident shortwave radiation

gypsum scarps and asymmetric fluvial valleys in evaporitic terrains the role of river migration landslides karstification and lithology ebro river ne spain abstract most of the spanish fluvial systems excavated in tertiary evaporitic gypsum formations show asymmetric valleys characterized by a stepped sequence of fluvial terraces on one valley flank and kilometric long and 100 m high prominent river scarp on the opposite side of the valley scarp undermining by the continuous preferential lateral migration of the river channel toward the valley margin leads to vertical to overhanging unstable slopes affected by a large number of slope failures that become the main geological hazard for villages located at the toe of the scarps detailed mapping of the gypsum scarps along the ebro and huerva rivers gypsum scarps demonstrates that landslides and lateral spreading processes are predominant when claystones crop out at the base of the scarp while rockfalls and topples become the dominant movement in those reaches where the rock mass is mainly constituted by evaporites the dissolution of gypsum nodules seasonal swelling and shrinking and dispersion processes contribute to a decrease in the mechanical strength of claystones the existence of dissolution enlarged joints sinkholes and severely damaged buildings at the toe of the scarp from karstic subsidence demonstrates that the interstratal karstification of evaporites becomes a triggering factor in the instability of the rock mass the genesis of asymmetric valleys and river gypsum scarps in the study area seem to be caused by the random migration of the river channel in the absence of lateral tilting related to tectonics or dissolution induced subsidence once the scarp is developed its preservation depends on the physicochemical properties of the substratum the ratio between bedrock erosion and river incision rates and climatic conditions that favour runoff erosion versus dissolution

global nature of the younger dryas cooling event inferred from oxygen isotope data from sulu sea cores the younger dryas an approximately 1 000 year long return to near glacial conditions interrupted the glacial holocene climate transition during which most of the northern hemisphere ice sheets melted evidence for the younger dryas event has been found mainly in sediments from the north atlantic ocean and northwest europe and this has led to the idea that the event was caused by an injection of meltwater into the north atlantic ocean1 3 this model however has been recently questioned in the light of coral reef data on the rate of sea level changes during this transition4 here we present high resolution oxygen isotope records from benthic and planktonic foraminifera from two radiocarbon dated cores in the sulu sea showing that the younger dry as occurred synchronously in the surface and deep waters of the sulu sea and the northern atlantic ocean by combining our results with other palaeoclimate data we suggest that the younger dry as event was a global phenomenon and we believe it to have been caused by low atmospheric co2concentrations

evidence of high energy events in the geological record mid holocene evolution of the southwestern donana national park sw spain abstract four phases are distinguished in the mid holocene evolution of the southwestern donana national park sw spain based on the multidisciplinary study of sediments in drill cores in the oldest phase 5500 5400 cal years bp a coastal brackish lagoon occupied the central part of the study area partly enclosed by the donana spit and limited by fluvial levees an evolution from subtidal to intertidal conditions characterized the areas located close to the inner side of the donana spit during the same phase the following phase 5400 5200 cal years bp is characterized by a high energy event tsunami which caused the breakthrough of the donana spit and the creation of new littoral strands in the inner areas in the first period of the third phase 5200 4200 cal years bp estuarine infilling was probably the dominant process with the accumulation of phyllosilicate rich clays in the lagoon bed this was followed by a renewed phase of instability 4200 4100 cal years bp indicated by the presence of fine storm lain deposits and thicker probably tsunami induced shelly deposits the last phase 4100 3700 cal years bp comprises a an infilling period with a diminution of the marine influence and b two new high energy events which caused the erosion of the donana spit and the creation of new cheniers in the last 7000 years the comparison of these results with a revision of both geological and historical records has revealed the occurrence of twenty tsunamis at least during this period in portugal and southern spain evidences of these high energy events are washover fans bioclastic coarse sized layers within salt marsh deposits or the presence of giant boulders and pebbles the determination of the recurrence period is very difficult owing to the very scarce data although our data and other authors do not discard a possible periodicity of 2000 years for a cycle of two events separated by 300 400 years

geochronology of betula extensions in pollen diagrams of alpine late glacial lake deposits a case study of the late glacial deposits of the gasserplatz soil archives vorarlberg austria pollen diagrams of alpine late glacial calcareous lake deposits show several extensions of betula the geochronology of these extensions cannot be based on radiocarbon dating due to reservoir effects of such lakes on the radiocarbon ages a robust geochronology can be based on the oxygen isotope stratigraphy additionally recognition of 12 920 calbp lst in the sediment cores provides a secure time marker the combined results of pollen macro remains and stable isotope analyses of the gasserplatz cores point to a correlation of the betula extensions with the oscillations in the oxygen isotope curve and are related to global climatic oscillations this is sustained by the correlation of the gasserplatz isotope oscillations with the oscillations as registered in the greenland ice cores comparison of the results of the gasserplatz cores with the results of similar alpine lake deposits makes clear that the fluctuations in the betula curve are not a local but a regional phenomenon

can the greenland climatic jumps be identified in records from ocean and land sharp jumps in climate punctuate the records from borings in the greenland ice cap during the time interval 60 000 to about 20 000 yr ago rapid fluctuations are also seen in foraminifera records for cores from the northern atlantic and in a pollen record from a core from a bog in the vosges mountains in france in this paper we present a new radiocarbon chronology for northern atlantic deep sea core v23 81 which permits comparison with the radiocarbon dated vosges mountains pollen record because of the lack of a 14c chronology for the greenland ice record and of distortions peculiar to each of the three records it is not yet possible to say whether or not the events are genetically related

summer temperature development 18 000 14 000 cal bp recorded by a new chironomid record from burgaschisee swiss plateau abstract the termination of the last ice age after the last glacial maximum lgm represents a dynamic period in the history of the circum north atlantic region so far there are few reliably dated climatic reconstructions covering the lateglacial period prior to 14 700 cal bp in central and northern europe we present a new chironomid record for the period 18 000 14 000 cal bp from burgaschisee switzerland chironomid assemblages immediately following glacier retreat were dominated by taxa indicative of cold oligotrophic conditions such as sergentia coracina type and micropsectra radialis type a gradual transition to assemblages with moderate abundances of taxa indicative of warmer climatic conditions such as dicrotendipes nevosus type and tanytarsus glabrescens type started after ca 16 100 cal bp this initial and gradual chironomid assemblage shift culminated in a more pronounced and rapid inferred temperature change at the oldest dryas bolling transition at ca 14 700 cal bp where further types indicative of warm conditions such as tanytarsus lactescens type first occurred and replaced chironomids indicative of colder conditions such as paracladius and protanypus we estimated past july air temperature changes from the chironomid assemblages by applying to the record a chironomid temperature transfer function that is based on chironomid distribution data from 274 lakes in switzerland and norway the resulting reconstruction which features a sample specific root mean square error of prediction of 1 36 1 46 c indicates temperatures around 9 c at the beginning of the record an initial gradual warming phase initiating at ca 16 100 cal bp is recorded reaching values around 10 c for the period 16 100 15 500 cal bp temperatures continue to increase reaching values around 12 c for the period preceding the bolling warming when temperatures rose rapidly to values around 15 c the early temperature rise to values of 10 12 c prior to the bolling warming agrees with widespread vegetation changes recently reported for this region based on palaeobotanical analyses which indicate a shift from herbaceous tundra to shrub tundra with low density tree birch stands with open canopies together these results suggest an earlier lateglacial temperature increase in southwest central europe than expected based on earlier palaeobotanical reconstructions although with a less pronounced warming than has been reported for ca 16 000 cal bp from south of the alps this early lateglacial warming agrees with glacier reconstructions which suggest several step wise reductions of glacier extent in this period as well as with evidence from other palaeotemperature reconstructions and suggests that not only southern europe but significant parts of europe north of the alps may have been characterized by early lateglacial warming well before the rapid warming at ca 14 700 cal bp

spectral albedos of sea ice and incident solar irradiance in the southern beaufort sea spectral albedos and incident spectral irradiances have been measured over the wavelength range 400 to 2400 nm on the sea ice near the naval arctic research laboratory narl at pt barrow alaska the observation interval extended from mid may when the ice was still relatively cold until mid june when summer melting was fully established the temporal dependence of albedo for the available surface types was obtained over this time interval showing a general decrease from snow and snow covered ice to blue ice and melt ponds data were also obtained for glacier ice on the athabasca glacier for melting lake ice and for certain other nonice surfaces in the vicinity of narl snow and ice albedos are characteristically highest at visible wavelengths decreasing strongly in the infrared because of the increase in absorption by ice and water local maxima in the spectra correspond to minima in the ice and water absorption variations in albedo are due primarily to differences in the vapor bubble density crystal structure and free water content of the upper layers of the ice incident spectral shortwave radiation was measured as a function of cloudiness and the optical thickness of arctic clouds is significantly less than the thickest clouds at lower latitudes the decrease of the infrared component relatiave to the visible portion of the irradiance with increasing cloud cover is determined this can give rise to an increase in wavelength integrated albedos of as much as 15 using the present data a graphical method is outlined by which visible near infrared satellite imagery can be used to distinguish among melt ponds open leads and other spring and summer sea ice surface types

an annually resolved record of western european vegetation response to younger dryas cooling abstract the regional patterns and timing of the younger dryas cooling in the north atlantic realm were complex and are mechanistically incompletely understood to enhance understanding of regional climate patterns we present molecular biomarker records at subannual to annual resolution by mass spectrometry imaging msi of sediments from the lake meerfelder maar covering the allerod younger dryas transition these analyses are supported by conventional extraction based molecular isotopic analyses which both validate the imaging results and constrain the sources of the target compounds the targeted fatty acid biomarkers serve as a gauge of the response of the local aquatic and terrestrial ecosystem to climate change based on the comparison of our data with existing data from meerfelder maar we analyse the short term environmental evolution in western europe during the studied time interval and confirm the previously reported delayed hydrological response to greenland cooling however despite a detected delay of western european environmental change of 135 years our biomarker data show statistically significant correlation with deuterium excess in greenland ice core at annual resolution during this time transgressive cooling this suggests a coherent atmospheric forcing across the north atlantic realm during this transition we propose that western european cooling was postponed due to major reorganization of the westerlies that were intermittently forcing warmer and wetter air masses from lower latitudes to western europe and thus resulted in delayed cooling relative to greenland

geomorphons a pattern recognition approach to classification and mapping of landforms abstract we introduce a novel method for classification and mapping of landform elements from a dem based on the principle of pattern recognition rather than differential geometry at the core of the method is the concept of geomorphon geomorphologic phonotypes a simple ternary pattern that serves as an archetype of a particular terrain morphology a finite number of 498 geomorphons constitute a comprehensive and exhaustive set of all possible morphological terrain types including standard elements of landscape as well as unfamiliar forms rarely found in natural terrestrial surfaces a single scan of a dem assigns an appropriate geomorphon to every cell in the raster using a procedure that self adapts to identify the most suitable spatial scale at each location as a result the method classifies landform elements at a range of different spatial scales with unprecedented computational efficiency a general purpose geomorphometric map an interpreted map of topography is obtained by generalizing allgeomorphons to a small number of the most common landform elements due to the robustness and high computational efficiency of the method high resolution geomorphometric maps having continental and even global extents can be generated from giga cell dems such maps are a valuable new resource for both manual and automated geomorphometric analyses in order to demonstrate a practical application of this new method a 30 m cell 1 geomorphometric map of the entire country of poland is generated and the features and potential usage of this map are briefly discussed the computer implementation of the method is outlined the code is available in the public domain

transpolar observations of the morphological properties of arctic sea ice save for an area between 8830 0 n and 8930 0 n where polynyas and thin ice were observed surveys of snow depth ice thickness and ice properties were conducted at ice stations thickness observations suggest a general latitudinal trend of increasing ice thickness moving northward with considerable variability from floe to floe and within a single floe average floe thicknesses varied from 1 0 to 2 8 m and the standard deviation of thickness on an individual floe was as large as 1 m ice crystallography showed a large amount of granular ice the average optical equivalent soot content was 4n g cg 1 for new snow 8 ng c g 1 for the surface granular layer of multiyear ice and 18 ng c g 1 for the interior of multiyear ice indicating a tendency of the particulates to concentrate at the surface with melting

tracing the laacher see tephra in the varved sediment record of the trzechowskie palaeolake in central northern poland abstract tephrochronological studies of partly varved sediments of trzechowskie palaeolake in central northern poland led to the finding of the late allerod laacher see tephra lst from the eifel volcanic field for the first time in a very distal site ca 840 km ene from its volcanic source the detection of glass shards of the lst involved a comprehensive combination of techniques i e biostratigraphical constrains high resolution xrf core scanning and areal xrf mapping of impregnated sediment slabs as well as detailed visual inspection of sediments the major element chemistry of volcanic glass confirmed the laacher see tephra composition in trzechowskie palaeolake sediments suggesting a deposition from the middle laacher see tephra mlst c or upper laacher see tephra ulst dispersal fans the finding of the lst in this palaeolake enables direct synchronisation with other high resolution archives in north central europe i e lake meerfelder maar rehwiese palaeolake to investigate regional variations of environmental responses at the onset of the younger dryas along a west east transect through north central europe