ka band backscattering from water surface at small incidence a wind wave tank study we report on an experiment conducted at the large pytheas wind wave facility in marseille to characterize the ka band radar return from water surfaces when observed at small incidence simultaneous measurements of capillary gravity to gravity wave height and slopes and normalized radar cross section nrcs were carried out for various wind speeds and scattering angles from this data set we construct an empirical two dimensional wave number spectrum accounting for the surface current to describe water surface motions from decimeter to millimeter scales some consistency tests are proposed to validate the surface wave spectrum which is then incorporated into simple analytical scattering models the resulting directional nrcs is found in overall good agreement with the experimental values comparisons are performed with oceanic models as well as in situ measurements over different types of natural surfaces the applicability of the present findings to oceanic as well as continental surfaces is discussed

reconstructing biomes from palaeoecological data a general method and its application to european pollen data at 0 and 6 ka biome models allow the results of experiments with atmospheric general circulation models to be translated into global maps of potential natural vegetation the use of biome models as a diagnostic tool for palaeoclimate simulations can yield maps that are directly comparable with palaeoecological pollen and plant macrofossil records provided these records are biomized i e assigned to biomes in a consistent way this article describes a method for the objective biomization of pollen samples based on fuzzy logic pollen types taxa are assigned to one or more plant functional types pfts then affinity scores are calculated for each biome in turn based on its list of characteristic pfts the pollen sample is assigned to the biome to which it has the highest affinity subject to a tie breaking rule modern pollen data from surface samples reflecting present vegetation across europe are used to validate the method pollen data from dated sediment cores are then used to reconstruct european vegetation patterns for 6 ka the reconstruction shows systematic differences from present that are consistent with previous interpretations the method has proved robust with respect to human impacts on vegetation and provides a rational way to interpret combinations of pollen types that do not have present day analogs the method demands minimal prior information and is therefore equally suitable for use in other regions with richer floras and or lower densities of available modern and fossil pollen samples than europe

methodology of the last climatic cycle reconstruction in france from pollen data abstract a numerical method has been devised to reconstruct the climate of the last climatic cycle from pollen data reliable annual reconstructions have been published recently for the two french long sequences of la grande pile and les echets covering the last 140 millennia this paper gives more details on the method used it proposes new reconstructions based on an extended modern pollen data base these reconstructions are consistent with the previous ones especially detailed information is obtained on the seasonal characteristics of climate computations of gcm on the climate variations from 125 kyr to 115 kyr b p are confirmed for western europe the insolation variations have induced at that time a decrease of seasonality accompanied by an increased cyclonic activity in winter this has been the beginning of the first ice growth after the last interglacial other glacier growth phases are detected at the end of substage 5c and particularly at the end of substage 5a

importance of peakedness in sea surface slope measurements and applications we recall the simple statistical concept that non gaussian distribution peakedness results from the compounding of random processes this idea is applied to observations and analysis of sea surface slopes as inferred using optical and microwave scattering measurements our study emphasizes the importance of identifying and quantifying the distribution variance and kurtosis from observations data are shown to indicate consistently non gaussian peakedness to indicate the need to report at least two parameters in an even order analysis and to indicate near equivalence between radar and optical data physical interpretation for observed infrequent steep slopes is given via compounding statistical processes where normally distributed short scale waves are modulated because of random fluctuations mainly associated with the underlying long wave field implications of non gaussian peakedness are provided for altimeter backscatter theory and for modeling wave breaking probability

late quaternary variations in tree cover at the northern forest tundra ecotone 1 accurate land cover reconstructions are essential to understanding the past and present biogeochemical and biogeophysical interactions between the land surface and atmosphere and the impacts of these interactions on climate here we quantitatively reconstruct late quaternary shifts in woody cover across the northern hemisphere forest tundra ecotone based on a synthesis of northern hemisphere pollen records and contemporary observations of woody cover from the advanced very high resolution radiometer sensor our reconstructions document the expansion of northern hemisphere forests following deglaciation and reveal significant hemispheric asymmetries in the holocene position steepness and history of the forest tundra ecotone in western canada for example forest expansion and infilling continued through the holocene while in much of northern asia forests reached their maximal expansion during the early holocene then retreated the woody cover reconstructions are generally consistent with macrofossil based reconstructions of northern tree line dynamics and complement them by extending study of the northern forest tundra ecotone from the tree line limit well mapped by macrofossils to the entire ecotone using the lund potsdam jena dynamic vegetation model we estimate that changes in northern forest density resulted in at least a 47 7 gt c increase in aboveground carbon sequestration between 21 and 9 ka a 13 9 gt c increase between 9 and 6 ka and a 3 5 gt c loss of aboveground carbon from northern forests after 6 ka this trajectory is consistent with atmospheric carbon isotopic measurements for the holocene which suggest carbon uptake by the terrestrial biosphere until 6 ka and small carbon releases from the terrestrial biosphere afterward

vegetation and climate dynamics during the holocene and eemian interglacials derived from lake baikal pollen records abstract the last interglacial li and holocene changes in annual precipitation p ann the mean temperature of the warmest t w and coldest t c month and the moisture index were reconstructed from continuous pollen records from lake baikal the holocene core 52 31 n 106 09 e presented in this study was recovered from a depth of 355 m in the 25 km wide underwater buguldeika saddle separating the southern sub basin of lake baikal from its central sub basin the biome reconstruction shows that tundra and steppe biomes have highest scores during ca 15 000 13 300 cal years b p and that taiga becomes a dominant vegetation type after ca 13 300 cal years b p our quantitative reconstruction indicates an onset of relatively warm and wet conditions soon after ca 10 000 cal years b p the warmest and wettest climate with t w 16 c p ann 480 mm and 0 9 1 has been reconstructed for ca 9000 7000 cal years b p in the lake baikal region this interval is characterized by the appearance and spread of hunter communities kitoi culture consistently a hiatus in the regional archaeological record 4900 4200 years b c or 6850 6150 cal years b p coincides with the interval of a major climate deterioration which followed the climatic optimum an attempt to find a relationship between the archaeological record and a spread of steppe and meadow communities in the lake baikal region demonstrates that despite a long habitation of the area the human impact on vegetation was local rather than regional and likely did not affect the pollen record from lake baikal the reconstructed peaks in the steppe biome scores during the last 9000 years are consistent with short one to five hundred year episodes of weak pacific summer monsoon supporting our interpretation that the holocene vegetation changes around lake baikal are associated with large scale circulation processes controlling regional water balance rather than with human activities thus our study proves the suitability of lake baikal pollen data for the reconstruction of natural vegetation and climate dynamics through the whole period from the onset of the li to the present comparison of the recent and the last interglacial suggests that the holocene climatic optimum was less pronounced e g lower summer and winter temperatures and annual precipitation sums than that of the li on the other hand pollen records demonstrate that the holocene forest phase already lasts some thousand years longer than that of the li the interglacial vegetation dynamics derived from the lake baikal pollen records can be satisfactorily explained by reconstructed changes in summer and winter temperatures and in available moisture the interglacial vegetation around lake baikal is dominated by the boreal forests which are associated with a generally warm and wet climate the high sea level associated with decreased ice volume appears to have had a greater impact on the siberian environments during the last and the recent interglacial than the direct effect of lower than present winter insolation reconstructed changes in the winter temperature correlate well with changes in the sea level and global ice volume while the summer temperatures derived from the lake baikal pollen records track changes in the summer insolation

last glacial vegetation reconstructions in the extreme continental eastern asia potentials of pollen and n alkane biomarker analyses the current study presents quantitative reconstructions of tree cover annual precipitation and mean july temperature derived from the pollen record from lake billyakh 65 17 n 126 47 e 340 m above sea level spanning the last ca 50 ka ca 50 000 cal yrs the reconstruction of tree cover suggests presence of woody plants through the entire analyzed time interval although trees played only a minor role in the vegetation around lake billyakh prior to 14 ka bp 5 this result corroborates low percentages of tree pollen and low scores of the cold deciduous forest biome in the pg1755 record from lake billyakh the reconstructed values of the mean temperature of the warmest month 8 10 c do not support larch forest or woodland around lake billyakh during the coldest phase of the last glacial between 32 and 15 ka bp however modern cases from northern siberia ca 750 km north of lake billyakh demonstrate that individual larch plants can grow within shrub and grass tundra landscape in very low mean july temperatures of about 8 c this makes plausible the hypothesis that the western and southern foreland of the verkhoyansk mountains could provide enough moist and warm microhabitats and allow individual larch specimens to survive climatic extremes of the last glacial reconstructed mean values of annual precipitation are about 270 mm during the last glacial interval this value is almost 100 mm higher than modern averages reported for the extreme continental north eastern siberia east of lake billyakh where larch dominated cold deciduous forest grows at present this suggests that last glacial environments around lake billyakh were never too dry for larch to grow and that the insufficient summer warmth was the main factor which limited tree growth during the last glacial interval the n alkane analysis of the siberian plants presented in this study demonstrates rather complex alkane distribution patterns which challenge the interpretation of the fossil records in particular extremely low n alkane concentrations in the leaves of local coniferous trees and shrubs suggest that their contribution to the litter and therefore to the fossil lake sediments might be not high enough for tracing the quaternary history of the needleleaved taxa using the n alkane biomarker method

measuring sea surface mean square slope with a 36 ghz scanning radar altimeter values of sea surface mean square slope mss computed from the backscattered power falloff with incidence angle measured by an airborne 36 ghz scanning radar altimeter are presented when the mss values are plotted against the 10 m wind speed extrapolated from the 46 to 110 m aircraft height for wind speeds up to 7 m s 1 the values scatter about a curve which is scaled from that obtained by wu 1990 by a factor of 0 85 wu s result was a reanalysis of the optical measurements of cox and munk 1954 the offset between the microwave and optical curves is reasonable because one would expect the surface to appear smoother to the microwave wavelength than to the optical this is unlike the mss values inferred from absolute power measurements at nadir by 14 ghz satellite altimeters which indicate a higher mss under light wind conditions than the optical measurements indicate for wind speeds below 7 m s 1 the peak of the backscattered power distribution is observed at nadir but for higher speeds the peak shifts off nadir in the downwind direction

relations between climatic changes and prehistoric human migrations during holocene between gissar range pamir hindu kush and kashmir the archaeological and ecological data in the beginning of the holocene hunter gatherer populations settled in the pamir plateau especially in the tectonic depression of markansu near the kara kul lake osh kona site 4100 m 9580 bp and 7145 bp these populations were well adapted to high altitude life conditions in summer they were using stone tools related to a cobble tool tradition that ranov considered as the local continuation of an asian middle palaeolithic ferghana darwaz or punjab however they disappeared during the second half of the holocene as well hunters gatherers characterised by a tradition close to markansu culture namely hissar culture appeared during the holocene in the northern mountains of the tajik afghan depression amu darya upper basin occupying the middle altitude valleys gissar range when neolithic populations began to develop at lower altitudes for ranov origin and destiny of both markansu and hissar cultures were the most important questions to solve in this region the department of prehistory national museum of natural history paris conducted field work in collaboration with the university of peshawar between 1996 and 1998 in the northernmost valley of the indus basin giving access to the wakhan corridor the upper yarkhun valley chitral district pakistan accessible only by foot was surveyed from 2500 to 4000 m altitude this allowed the discovery of 6 sites yielding lithic artefacts among which half are cobble tools they attest to human activity later than 5500 bp suggesting population movements between the amu darya and indus basins the consequences of the quaternary climate oscillations between south asian monsoon and northern hemisphere influences on the one hand and the impact on biotopes of the increasing pastoral activity on the other hand are discussed as probable causes for the disappearance of the mountainous nomadic hunters of central asia

the distribution of late quaternary woody taxa in northern eurasia evidence from a new macrofossil database we present a database of late quaternary plant macrofossil records for northern eurasia from 23 to 180 e and 46 to 76 n comprising 281 localities over 2300 samples and over 13 000 individual records samples are individually radiocarbon dated or are assigned ages via age models fitted to sequences of calibrated radiocarbon dates within a section tree species characteristic of modern northern forests e g picea larix tree betula are recorded at least intermittently from prior to the last glacial maximum lgm through the lgm and lateglacial to the holocene and some records locate trees close to the limits of the scandinavian ice sheet supporting the hypothesis that some taxa persisted in northern refugia during the last glacial cycle northern trees show differing spatio temporal patterns across siberia deciduous trees were widespread in the lateglacial with individuals occurring across much of their contemporary ranges while evergreen conifers expanded northwards to their range limits in the holocene

pyrite textures and compositions in jiangshan gold deposit bengbu uplift southeastern north china craton implications for ore genesis abstract many phanerozoic gold deposits in east china e g those in the jiaodong peninsula hosted either in granitoids of the same age or precambrian basement rocks of the north china craton have been well documented the bengbu uplift along the southeastern margin of the north china craton is believed to be the western extension of the jiaodong gold province separated by the large scale sinistral tan lu fault zone however no deposits with more than 10 t gold resources have been discovered in the bengbu uplift and it is unclear whether the timing and genesis of gold deposits in the bengbu uplift are similar to those in the jiaodong gold province in this study laser ablation inductively coupled plasma mass spectrometry trace element analyses mapping and in situ sulfur isotope analyses were used to determine the source and process of gold mineralization in jiangshan gold deposit the largest in the region the wall rocks in the jiangshan gold deposit are metamorphic rocks of the neo archaean wuhe group and the ore bodies are controlled by the eastern part of the guangou xiajijia fault four stages were identified from cross cutting relationships and textural and mineralogical characteristics pre ore stage stage i quartz pyrite muscovite alteration stage ii pyrite quartz veins stage iii and quartz pyrite veinlets stage iv each of the four stages is characterized by a different type of pyrite here named py1 py2 py3 and py4 py1 formes the core of py2 has elliptical and irregular shapes contains low gold and arsenic concentrations and has 34s values of 0 86 2 86 py2 is hosted in quartz pyrite muscovite altered rocks with disseminated and aggregated euhedral to subhedral textures it has elevated arsenic content and the lowest gold content with some rhythmic zones and fractures stage ii was crosscut by stage iii py3 has anhedral textures with brittle deformation and occupies fractures in stage iii pyrite quartz veins the gold content of py3 is slightly higher than that of py1 and py2 but its arsenic content is extremely low py4 in the quartz pyrite veinlets has cataclastic textures with the highest gold and chalcophile element contents native gold and electrum also formed in stage iv which is the main gold stage in the jiangshan deposit the 34s values of py2 py4 are broadly similar 5 79 7 98 suggesting a common sulfur source based on previous studies and higher 34s values of hydrothermal pyrite the fluid sulfur isotopes are interpreted to relate to degassing of the mantle wedge metasomatized by slab fluids during the westward subduction of the palaeo pacific plate beneath the north china craton during the early cretaceous based on the geological characteristics of the deposit we classify the jiangshan gold deposit as a jiaodong fracture disseminated type gold deposit which occurs as disseminated veinlets and disseminated mineralization in wallrocks along fracture zones tectonic events may be the most important factor in gold mineralization in fracture disseminated type gold deposits

a comparison of metallogenetic geological conditions of gold deposits between the bengbu wuhe area in anhui and eastern shandong province based on analysis of the previous results the study compared the metallogenetic geological conditions of gold deposits between the bengbu wuhe area and eastern shandong province on both sides of the tan lu fault zone it is shown that the paleoproterozoic wuhe complex in bengbu wuhe has high gold abundance which is yet significantly lower than the archaean jiaodong group in eastern shandong province though magmatic rocks were widely developed in bengbu wuhe the magmatism and the related tan lu fault system s development degree and activity were all weaker than those in eastern shandong province the material tracing of the magmatic rocks in bengbu wuhe revealed that the magma came from the lower crust of the yangtze craton but the deeper mantle material took part in the magmatism and mineralization in eastern shandong province as affected by the deep fracture the development degree of the main fractures in bengbu wuhe becomes weaker when they were far away from the tan lu fault in the west while the left lateral transcurrent fracture systems were developed widely and multi period movements occurred in jiaodong therefore the two areas have significant differences in basement strata magmatic rocks crust mantle intersection and ore controlling faults which may be the main cause of the mineralization differences between the gold deposits on both sides

pollen based continental climate reconstructions at 6 and 21 ka a global synthesis subfossil pollen and plant macrofossil data derived from 14c dated sediment profiles can provide quantitative information on glacial and interglacial climates the data allow climate variables related to growing season warmth winter cold and plant available moisture to be reconstructed continental scale reconstructions have been made for the mid holocene mh around 6 ka and last glacial maximum lgm around 21 ka allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth assessment report ar5 of the intergovernmental panel on climate change the synthesis of the available mh and lgm climate reconstructions and their uncertainties obtained using modern analogue regression and model inversion techniques is presented for four temperature variables and two moisture variables reconstructions of the same variables based on surface pollen assemblages are shown to be accurate and unbiased reconstructed lgm and mh climate anomaly patterns are coherent consistent between variables and robust with respect to the choice of technique they support a conceptual model of the controls of late quaternary climate change whereby the first order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance

environmental change in yellow sea during the last deglaciation to the early holocene 15 000 8 000 bp abstract this study is the first reconstruction of the paleoenvironment and paleovegetation during the holocene interglacial and last deglaciation periods of the yellow sea carbon isotope and biomarker n alkane and alkenone compositions of organic carbon matter om from core 11 ys pcl14 collected from the central yellow sea recorded past changes in east asian monsoon eam climates the result shows the variability of the eam affected the sedimentary profile of total organic carbon toc the stable isotopes of bulk organic carbon 13 c org the atomic ratio of carbon and nitrogen c n ratio and biomarker content the oscillations of toc along the sediment core might be associated with the paleoceanographic conditions changes in the sea level related to the contribution of the autochthonous and allochthonous om input two climatic conditions were distinguished warm humid and cold dry based on the n alkane proxy and the observed changes in 13 c of individual n alkane 13 c alk between the holocene and last deglaciation were attributed to changes in plant distribution type a shift in vegetation type between climatic periods occurred as a result of different photosynthetic response to co 2 and temperature among c 3 and c 4 plants the most interesting new finding of this work is the fact that alkenone derived temperature changed independently with global climate change which might be related to the influence of the kuroshio current in the yellow sea the variations in the intensity of the eam could be the main mechanism accounting for the paleoenvironmental and paleoceanographic variation observed in the central yellow sea

ocean wave slope observations using radar backscatter and laser altimeters abstract combination of laser and radar aboard an aircraft is used to directly measure long gravity wave surface tilting simultaneously with nadir viewing microwave backscatter from the sea surface the presented dataset is extensive encompassing varied wind conditions over coastal and open ocean wave regimes laser derived slope statistics and ka band 36 ghz radar backscatter are detailed separately to document their respective variations versus near surface wind speed the slope statistics measured for 1 2 m show good agreement with cox and munk s oil slickened sea measurements a notable exception is elevated distribution peakedness and an observed wind dependence in this likely proxy for nonlinear wave wave interactions aircraft ka band radar data nearly mimic ku band satellite altimeter observations in their mean wind dependence the present calibrated radar data along with relevant observational and theoretical studies suggest a large 5 db bias in previous ka band results next wave

ice age terrestrial carbon changes revisited n shackleton 1977 first proposed that changes in the marine 13 c record 13 c could be used to infer ice age changes in carbon storage on land the previously published best estimate from the marine record is equivalent to about 490 gt 0 32 13 c however adams et al 1990 utilized a pollen database to estimate a 1350 gt change in carbon storage which would cause a 13 c of about 0 90 the nearly trillion ton difference in estimates amounts to almost half of the total carbon stored on land to address the nature of this discrepancy i have reexamined the terrestrial carbon record based on a new pollen database compiled by r webb and the cooperative holocene mapping project cohmap group i estimate about 750 1050 gt glacial interglacial change in terrestrial carbon storage with the range reflecting uncertainties in carbon storage values for different biomes additional uncertainties apply to rainforest and wetland extent and presence of c4 plants which have a significantly different isotopic signature than c3 plants although some scenarios overlap a new estimate of carbon storage based on the oceanic 13 c record revised to 0 40 and 610 gt most estimates seem to fall outside the envelope of uncertainty in the marine record several possible explanations for this gap involve 1 a missing sink may be involved in land sea carbon exchange e g continental slopes 2 the geochemistry of the exchange process is not understood 3 carbon storage by biome may have changed under ice age boundary conditions or 4 the standard interpretation of whole ocean changes in the marine 13 c record requires reevaluation this latter conclusion receives some support from comparison of the 13 c records for 18 o stages 2 and 6 for the stage 6 glacial the 13 c changes are 50 60 larger than for the stage 2 glacial yet implications of increased aridity are not supported by longterm trends in atmospheric dust loading to summarize the above analysis implies that despite the uncertainties remaining in estimates of terrestrial carbon storage changes a case can be made that our understanding of the transfer process is incomplete and that the eventual explanation may require clarification of factors affecting the marine 13 c record

late quaternary vegetation and lake system dynamics in north eastern siberia implications for seasonal climate variability although the climate development over the holocene in the northern hemisphere is well known palaeolimnological climate reconstructions reveal spatiotemporal variability in northern eurasia here we present a multi proxy study from north eastern siberia combining sediment geochemistry and diatom and pollen data from lake sediment cores covering the last 38 000 cal years our results show major changes in pyrite content and fragilarioid diatom species distributions indicating prolonged seasonal lake ice cover between 13 500 and 8900 cal years bp and possibly during the 8200 cal years bp cold event a pollen based climate reconstruction generated a mean july temperature of 17 8 c during the holocene thermal maximum htm between 8900 and 4500 cal years bp naviculoid diatoms appear in the late holocene indicating a shortening of the seasonal ice cover that continues today our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the holocene planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the anthropocene we assess other palaeolimnological studies to infer the spatiotemporal pattern of the htm and affirm that the timing of its onset a difference of up to 3000 years from north to south can be well explained by climatic teleconnections the westerlies brought cold air to this part of siberia until the laurentide ice sheet vanished 7000 years ago the apparent delayed ending of the htm in the central siberian record can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures and decreases in contrast in insolation between seasons during the mid to late holocene as well as lacking differentiation between summer and winter trends in paleolimnological reconstructions

statistical characterization of short wind waves from stereo images of the sea surface we propose a methodology to extract short scale statistical characteristics of the sea surface topography by means of stereo image reconstruction the possibilities and limitations of the technique are discussed and tested on a data set acquired from an oceanographic platform at the black sea a validation is made with simultaneous it in situ measurements as well as results from the literature we show that one and two point properties of the short scale roughness can be well estimated without resorting to an interpolation procedure or an underlying surface model we obtain the first cumulants of the probability distribution of small scale elevations and slopes as well as related structure functions we derive an empirical parametrization for the skewness function which is of primary importance in analytical scattering models from the sea surface

satellite and pollen based quantitative woody cover reconstructions for northern asia verification and application to late quaternary pollen data abstract accurate reconstruction of late quaternary vegetation cover is necessary for better understanding of past vegetation dynamics the role of vegetation feedbacks in glacial interglacial climate variations and for validating vegetation and climate models in this paper over 1700 surface pollen spectra from the former soviet union mongolia northern china and northern japan together with data from the advanced very high resolution radiometer avhrr were used to calibrate modern analogue method for quantitatively reconstructing past woody cover from fossil pollen data the avhrr based estimates of woody cover percentages within a 21 21 km window around pollen sampling sites were attributed to the respective modern pollen spectra reconstructions of modern woody cover using the pollen data and best modern analogues bma method matched well to the original avhrr based estimates for both total woody cover r 2 0 77 and its fractions including broad leaved r 2 0 66 needle leaved r 2 0 79 deciduous r 2 0 60 and evergreen r 2 0 76 woody cover discrepancies in the pollen avhrr cross validation may be caused by long distance transport of arboreal pollen patchy forest distributions underrepresentation of larix and populus in pollen records and errors in the avhrr classification the generally strong correlations encourage application of the modern analogue approach for reconstructing late quaternary variations in vegetation cover from northern asian fossil pollen records at the last glacial maximum lgm 21 000 cal yr bp areas presently occupied by boreal forest were much more open suggesting a reduction in total woody cover to below 20 at most modern forest sites pollen records from northern and central siberia suggest a rather quick spread of tree and shrub vegetation after 15 000 cal yr bp presumably in response to increased summer insolation woody cover histories are spatially variable in the modern forest steppe where tree growth is largely controlled by the ratio of annual actual over potential evapotranspiration which serves as an index of moisture availability in northwestern mongolia woody cover percentages decreased between 9000 and 5000 cal yr bp and again between 2000 and 1000 cal yr bp and may be linked to shifts in intensity of the pacific monsoon in contrast pollen data from the kazakhstan forest steppe where atmospheric precipitation is associated with the atlantic westerly flow suggest that woody cover density reached modern levels only during the last millennium

late quaternary environmental changes in misiones subtropical ne argentina deduced from multi proxy geochemical analyses in a palaeosol sediment sequence abstract a 4 5 m long sediment core from a small basin in the province of misiones ne argentina was analyzed in a multi proxy geochemical approach major and minor elemental composition c org n hi oi 13 c org n alkanes and compound specific 13 c analyses of biomarkers in order to contribute to the reconstruction of the late quaternary environmental and climate history of subtropical south america the results of the elemental analyses and radiocarbon dating indicate different sediment provenances for unit a the holocene unit b the late glacial and the last glacial maximum lgm and unit c the inca huasi wet phase before 40 ka bp a sedimentary hiatus after 40 ka bp is interpreted as a pronounced pre lgm dry phase with landscape erosion deflation multi proxy geochemical characterization of the soil organic matter som shows that especially i the stable carbon isotopic composition 13 c of the grass derived alkanes n c 31 and n c 33 ii the alkane ratio n c 31 n c 27 and iii lacustrine derived short and mid chain alkanes are valuable proxies for the reconstruction of the palaeoenvironment a transition from c3 tree dominance to c4 grass dominance is recorded at the end of the inca huasi wet phase in unit b the ratio n c 31 n c 27 documents forest expansion at the beginning of a late glacial wet phase more positive 13 c values in unit a reflect the increasing contribution of c4 grasses and or cam plants to the som during the holocene and a human impact on the formation of this unit may be possible the results are in good agreement with other tropical subtropical palaeoenvironmental records and highlight the importance and temporal variability of the palaeo south american summer monsoon sasm

origins of biomarker aliphatic hydrocarbons in sediments of alpine lake ximencuo china abstract aliphatic hydrocarbons in lake sediments are important lipid biomarkers that have been widely used in paleoenvironmental reconstructions on the dual premises that their sources are defined and that they resist degradation as a test of these premises we have analyzed the n alkane and n alkene distributions in the leaf waxes of the eight dominant plants and in the surface soil at five locations surrounding lake ximencuo a typical alpine lake on the eastern qinghai tibetan plateau to explore the origins delivery and deposition of these molecular biomarkers in the surface sediment of this restricted lake system distinctive distributions of n alkanes and n alkenes were found in the leaf waxes of the different plants unlike those of the plants the n alkane distributions in the soil are virtually identical at the locations around the lake and the n alkenes found in the plant waxes are rare in the surface soil these differences imply extensive diagenetic degradation of the soil hosted hydrocarbons in contrast to the soils the hydrocarbon distribution in the lake sediment is more like those of the plants it contains n alkanes that range from c 15 to c 33 with a maximum abundance at n c 31 and includes a suite of n c 21 1 to n c 28 1 alkenes with odd carbon preference although they may originate from land plant debris that is washed directly into the lake the alkenes are postulated to originate principally from algae living in the lake because of their absence in the soils the biomarker hydrocarbons in the lake sediments appear to integrate multiple inputs including plants around the lake glacial meltwaters and algae fungi and microbes within the lake the results of this study highlight that different groups of aliphatic hydrocarbons in lake sediments can have different origins and consequently are likely to reflect different aspects of past environmental conditions hence consideration of the multiple possible origins of these biomarkers has the potential to expand and refine paleoenvironmental reconstructions that employ them

reconstruction of environmental changes during the late glacial and holocene reflected in a soil sedimentary sequence from the lower selenga river valley lake baikal region siberia assessed by lipid molecular proxies abstract sediments of lake baikal and smaller lakes in its surroundings have been frequently used to trace paleoenvironmental changes however these sediments integrate environmental proxies over large areas and the processes leading to alteration of terrestrial signals are not fully understood more specific information can be derived from terrestrial archives such as alternating soil sediment sequences near the village of burdukovo southeast of lake baikal such sequences are accessible along the 5 m high right terrace of the selenga river however terrestrial archives can be associated with degradation of organic matter therefore lipid molecular proxies were applied in the current study to trace environmental and vegetation shifts as well as incorporation and degradation of organic matter alkane and fatty acid molecular proxies as part of the lipid fraction are well known for their diagnostic character to trace sources of organic matter and its degradation several parameters including the carbon preference indices of alkanes and fatty acids indicated a well preservation of the organic matter in the investigated sequence furthermore the organic matter in the c horizons of the terrestrial upper part of the sediments was most likely overprinted by rooting of the plants growing on respective overlaying soils as reflected by the average chain length of fatty acids and alkanes and the relative composition of long chain n alkanes c 25 33 the 3 5 m thick sequence enabled tracing of vegetation shifts the alkane composition argued for changes in the grass dominated vegetation cover within the different phases of the holocene until today whereas a birch and willow dominated deciduous forest vegetation as traced in other archives of the larger baikal area could not be determined in the burdukovo sequence by lipid molecular proxies the scatter in the alkane and fatty acid composition revealed only minor vegetation shifts throughout the holocene nevertheless some changes in the lipid composition indicated a change in the plant community as coniferous trees have often similar alkane patterns to grass vegetation it cannot be excluded that conifers also contributed to a certain degree to the molecular record in the burdukovo sequence the general decrease in the carbon preference index of alkanes since approximately 4 ka bp until recent times further argues for an increasing admixture of coniferous lipids to the record lipid molecular proxies of sediment that formed 2 8 2 6 ka bp revealed the incorporation of deciduous tree derived organic matter most likely originating from birch that grew elsewhere in the catchment of the selenga river the proxies enabled an assessment of site specific vegetation shifts and degradation of organic matter in the soil sediment sequence of the burdukovo area and thus provide more specific information related to a certain area than lacustrine sediments integrating over larger catchments

peakedness effects in near nadir radar observations of the sea surface the simulation and interpretation of microwave sea radar return in the near nadir region are still issues in view of the limitations of the geometrical optics approximation and the multiscale and non gaussian nature of the surface we show that an unambiguous and fully consistent physical approach can be reached in the framework of the physical optics the model is developed on the basis of various satellite and airborne c ku and ka band measurements using different reference surface roughness spectra as found the introduction of a peakedness correction based upon the excess kurtosis of slopes is necessary to obtain consistent analysis across the microwave frequency range the model yields accurate simulations for the omnidirectional near nadir normalized radar cross section in different frequency bands provided the spectrum satisfies some a priori constraints on the distribution of the total and filtered slopes

reply to comment by paul a hwang on a study of the slope probability density function of the ocean waves from radar observations by d hauser et al in response to the comment of hwang 2009 this paper presents an addendum to the study published by hauser et al 2008 on the mean square slopes mss derived from radar observations at c band and incidence angles between 7 and 21

impacts of paleohydrological changes on n alkane biomarker compositions of a holocene peat sequence in the eastern european russian arctic coupled analyses of n alkane biomarkers and plant macrofossils from a peat plateau deposit in the northeast european russian arctic were carried out to assess the effects of past hydrology on the m

incorrect when uncorrected reconstructing vegetation history using n alkane biomarkers in loess paleosol sequences a case study from the saxonian loess region germany abstract this study aims at contributing to the reconstruction of the paleoenvironment of the saxonian loess region by investigating sedimentary n alkanes as plant leaf wax derived biomarkers in two loess paleosol sequences lpss namely the gleina and the rottewitz lpss the weichselian paleosols are characterised by n alkane concentration maxima when compared to the loess layers when this coincides with high odd over even predominances oeps this points not only to increased n alkane input and or production but also to increased n alkane preservation in the soils namely in gleysols with water logged edaphic conditions by contrast the buried cambisols reveal low oeps indicating accelerated degradation under aerobic edaphic conditions the n alkane concentrations in the truncated eemian interglacial paleosol are very low this reflects the removal of the formerly n alkane enriched eemian topsoil low n alkane input into the b t s d horizon subsoil horizon of the eemian luvisol and or strong soil organic matter mineralization four investigated n alkane ratios show distinct variations during the weichselian tempting inferences of vegetation changes in terms of varying contributions of tree shrub derived dominated by n c 27 or n c 29 versus grass derived dominated by n c 31 or n c 33 n alkanes however using the oep as a proxy for degradation and considering that n alkane ratios are prone to degradation effects the above interpretation is very likely incorrect degradation can account for most variability of the n alkane ratios applying an endmember model based on a modern n alkane reference dataset allows estimating the contribution of tree shrub versus grass derived n alkanes semi quantitatively these modelling results suggest that both the gleina and the rottewitz lpss were formed under prevailing grassland minor contributions of trees shrubs are only likely for the gleinaer soil complex in rottewitz lps for the top of a brown gleysol in gleina lps and the holocene soil the weichselian vegetation changes as inferred from the uncorrected n alkane ratios are not confirmed overall the n alkane results support the idea that the gleinaer soil complex in gleina and rottewitz lps respectively are not identical but rather are chronostratigraphic equivalents more favourable regional climatic conditions presumably occurred in the southwesterly exposed rottewitz locality and allowed tree shrub vegetation to grow during favourable periods of the weichselian a major shortcoming of the n alkane biomarker method is that only vegetation changes of deciduous woodland to grassland and vice versa can be reconstructed because coniferous trees exhibit by two to three orders of magnitude lower n alkane concentrations

the southern ocean waves experiment part iii sea surface slope statistics and near nadir remote sensing abstract during the southern ocean waves experiment sowex registered ocean wave topography and backscattered power data at ka band 36 ghz were collected with the nasa scanning radar altimeter sra off the coast of tasmania under a wide range of wind and sea conditions from quiescent to gale force winds with 9 m significant wave height collection altitude varied from 35 m to over 1 km allowing determination of the sea surface mean square slope mss the directional wave spectrum and the detailed variation of backscattered power with incidence angle which deviated from a simple gaussian scattering model the non gaussian characteristics of the backscatter increased systematically with the mss suggesting that a global model to characterize ka band radar backscatter from the sea surface within 25 of nadir might be possible

characterisation and palaeoclimate of a loess like permafrost palaeosol sequence in ne siberia abstract we studied a 15 m high loess like permafrost palaeosol sequence the tumara palaeosol sequence tps which developed on a middle pleistocene fluvio glacial terrace of the tumara river various analytical methods were applied to characterise the tps similar to typical loess palaeosol sequences e g in china europe etc pedogenetic clay formation mineral weathering and smaller grain sizes are interpreted as representing warmer and more favourable climatic conditions interglacials or interstadials soil organic matter som however reveals an unfamiliar inverse pattern high organic carbon contents c org 1 characterise the dark grey glacial palaeosols whereas lower contents c org 0 5 are found in the brown interglacial stadial palaeosols this can be explained with permafrost and water logging having inhibited som mineralisation during cold periods d l ratios of aspartic acid and lysine proved to be useful proxies for both som aging and palaeotemperature with amino acid racemization being enhanced in interglacial stadial palaeosols on the basis of the geochemical and grain size results further palaeoclimatically relevant proxies describing the palaoewind strength u ratio the mineral weathering chemical index of alteration rb k and the changing mineral input signal ba ti zr ti al were applied to the tps in combination with numeric dating results radiocarbon and luminescence and in the context of other northern hemispheric records the simple warm cold stratigraphy as derived from the palaeoenvironment climate proxies suggests that the tps represents the last 240 000 years

molecular isotopic stratigraphy of long chain n alkanes in lake baikal holocene and glacial age sediments the molecular distribution and the carbon isotopic composition d 13 c of n alkanes extracted from a lake baikal core spanning the last 20 kyr of sediment accumulation have been investigated a terrestrial origin has been inferred for the odd carbon numbered long chain c27 n alkanes on the basis of the observed high cpi27 33 values range 8 7 10 8 typical of n alkanes derived from leaf waxes of higher plants a shift in the abundance of n c27 alkane relative to n c31 homologue is observed across the late pleistocene glacial holocene interglacial climate change perhaps indicative of the climate induced vegetational change previously deduced from palynological analyses compound specific isotope analyses indicate remarkably uniform d 13 c values in the range of 31 0 to 33 5 for the leaf wax c27 c33 nalkanes in the entire cored sequence such an isotopic compositional range is characteristic for n alkanes biosynthesized by plants utilizing the c3 photosynthetic pathway our data suggest that the observed 13 c enrichment in the bulk organic matter in the glacial age sediments relative to d 13 c values of total organic carbon in the holocene section is therefore unlikely to be attributed to an expansion of c4 type vegetation in the baikal watershed during the late pleistocene glacial interval 2000 elsevier science ltd all rights reserved

holocene climate conditions in central yakutia eastern siberia inferred from sediment composition and fossil chironomids of lake temje abstract a 380 cm long sediment core from lake temje central yakutia eastern siberia was studied to infer holocene palaeoenvironmental change in the extreme periglacial setting of eastern siberia during the last 10 000 years data on sediment composition were used to characterize changes in the depositional environment during the ontogenetic development of the lake temje the analysis of fossil chironomid remains and statistical treatment of chironomid data by the application of a newly developed regional russian transfer functions provided inferences of mean july air temperatures tjuly and water depths wd reconstructed wds show minor changes throughout the core and range between 80 and 120 cm all the fluctuations in reconstructed water depth lie within the mean error of prediction of the inference model rmsep 0 35 so it is not possible to draw conclusions from the reconstructions a qualitative and quantitative reconstruction of holocene climate in central yakutia recognized three stages of palaeoenvironmental changes the early holocene between 10 and 8 ka bp was characterized by colder than today and moist summer conditions cryotextures in the lake sediments document full freezing of the lake water during the winter time a general warming trend started around 8 0 ka bp in concert with enhanced biological productivity reconstructed mean tjuly were equal or up to 1 5 c higher than today between 6 0 ka and 5 0 ka bp during the entire late holocene after 4 8 ka bp reconstructed mean tjuly remained below modern value limnological conditions did not change significantly the inference of a mid holocene climate optimum supports scenarios of holocene climatic changes in the subpolar part of eastern siberia and indicates climate teleconnections to the north atlantic realm

last glacial interglacial vegetation and environmental dynamics in southern siberia chronology forcing and feedbacks abstract radiocarbon dated pollen and diatom records from lake kotokel in southern siberia help to reconstruct the environmental history of the area since 47 kyr bp pollen spectra composition and reconstructed biome scores suggest predominance of a tundra steppe vegetation and variable woody cover 5 20 between 47 and 30 kyr bp indicating generally a harsh and unstable climate during this interval conventionally regarded as the interstadial within the last glacial the short term climate amelioration episodes in the glacial part of the records are marked by the peaks in taiga and corresponding minima in steppe biome scores and appear synchronously with the hemispheric temperature and precipitation changes recorded in the greenland ice cores and chinese stalagmites transition to full glacial environments occurred between 32 and 30 kyr bp the interval at 30 24 kyr bp was probably the driest and coldest of the whole record as indicated by highest scores for steppe biome woody coverage

vegetation and climate changes around the lama lake taymyr peninsula russia during the late pleistocene and holocene a continuous lacustrine sequence from the western part of lama lake 69 32 n 90 12 e complemented by a peat sequence from the lake catchment provides the first detailed environmental reconstruction for the late glacial and holocene on the taymyr peninsula scarce steppe like communities with artemisia poaceae and cyperaceae dominated during the late glacial tundra like communities with betula nana dryas and salix grew on more mesic sites there are distinct climatic signals which may be correlated with the bolling and allerod warming and middle and younger dryas cooling the late glacial preboreal transition at about 10 000 14c yr bp was characterized by changes from predominantly open herb communities to shrub tundra ones larch forest might have been established as early as 9700 9600 14c yr bp whilst shrub alder came to the area ca 9500 9400 14c yr bp and spruce did not reach area before ca 9200 14c yr bp spruce larch forests with shrub alder and tree birch dominated the vegetation around the lama lake from ca 9000 14c yr bp dwarf birch communities were also broadly distributed the role of spruce in the forest gradually decreased after 4500 14c yr bp the vegetation cover in the lama lake area became similar to the modern larch spruce forest ca 2500 14c yr bp a pollen based biome reconstruction supports a quantitative interpretation of the pollen spectra climate reconstructions obtained with information statistical and plan functional type methods show very similar trends in reconstructed july temperature since ca 12 300 14c yr bp while precipitation anomalies are less coherent especially during the late glacial holocene transition

simulation of l band bistatic returns from the ocean surface a facet approach with application to ocean gnss reflectometry we present the implementation of a facet based simulator to investigate the forward scattering of l band signals from realistic sea surfaces and its application to spaceborne ocean global navigation satellite system gnss reflectometry this approach provides a new flexible tool to assess the influence of the ocean surface roughness on scattered gnss signals the motivation stems from the study by clarizia which revealed significant differences between delay doppler maps ddms obtained from uk dmc satellite data and ddms simulated with the zavorotny voronovich z v model here the scattered power and polarization ratio pr are computed for explicit 3 d ocean wave fields using a novel implementation of the kirchhoff approximation ka which we call the facet approach fa we find that the fa is consistent with the full ka and the geometrical optics go used in the z v model while being less computationally expensive than the ka and able to represent polarization effects not captured by the go instantaneous maps of the bistatic normalized radar cross section computed with the fa show clear patterns associated with the underlying waves the wave field is particularly visible in the pr indicating that the scattering is generally dominated by the hh component particularly from ocean wave troughs polarization effects show for the first time a strong correlation to the explicit sea surface from which the scattering originated ddms of the scattered power computed with the fa reveal patchy patterns and power distributions that differ from those obtained with z v and show closer similarities with observed ddms from uk dmc

lipid biomarker δ13c and plant macrofossil stratigraphy of a scottish montane peat bog over the last two millennia abstract seven horizons of a peat core covering the last 2000 years from moine mhor a blanket bog in the cairngorm mountains scotland have been examined for the carbon number distributions of the long chain hydrocarbon alcohol and acid components using gas chromatography gc and gas chromatography mass spectrometry gc ms compound specific 13 c values for individual n alkanes were obtained using gas chromatography isotope ratio mass spectrometry gc irms the lipid biomarker distributions and the 13 c values have been compared with those of eleven species of living plant dominant at the contemporary surface of the bog the observed lipid stratigraphy shows only partial agreement with that calculated using macrofossil abundance data and the lipid distributions for the living taxa a result which reflects the inherent uncertainties in both the lipid biomarker and the macrofossil approaches to palaeoenvironmental stratigraphy the carbon isotope values for the individual n alkanes of the plants 27 6 to 36 6 and of the peat layers 29 to 31 7 are as expected for the c 3 photosynthetic pathway however the n alkanes from the surface samples were more depleted by 2 in 13 c than those from the rest of the core a negative shift which may in part reflect the shift 1 2 in 13 c estimated for co 2 in a pre industrialised to an industrialised atmosphere

evidence for humid conditions during the last glacial from leaf wax patterns in the loess paleosol sequence el paraiso central spain abstract the mediterranean region is affected by the first consequences of anthropogenic climate change and suffers from aridization and drought periods reconstructing past climate and environmental changes might help to put those consequences into context identify underlying mechanisms and improve predictions here we present leaf wax analyses for the loess paleosol sequence lps from el paraiso located in central spain and a selection of plants growing there today the long chain n alkanes in almost the whole lps are characterized by the dominance of c29 c31 and c33 indicating the presence of grasses and drought adapted tree species such as juniperus and olea however samples correlated with marine isotope stage mis 2 29 14 ka have higher abundances of c25 c27 and c29 which may signal the presence of less drought adapted deciduous trees and more humid conditions n alkanoic acid patterns can tentatively be interpreted to confirm these results but are less robust because more plant species are needed for comparison our findings and interpretation are in line with climate modelling studies that suggest a southward shift of the westerlies and storm tracks during mis 2 with fluvial and lacustrine records and with glacial refugia for temperate trees in southern europe compound specific isotope analyses will hopefully soon provide additional information about paleoclimatic and hydrologic changes and help establish a more precise and robust age control

investigation of azimuthal variations from x band medium grazing angle sea clutter the ingara x band fully polarimetric medium grazing angle sea clutter data set was collected in the australian maritime environment over an angular range of 360 in azimuth and from 15 to 45 in grazing this paper reports further analysis of this data set focusing on understanding the azimuth variation to enable improved simulation accuracy and extraction of relevant geophysical parameters this includes some original properties of the co and cross polarized normalized radar cross section as a function of the scattering geometry and sea surface parameters we also assess the performances and limitations of recent sea surface scattering models in the light of this rich data set

comment on a study of the slope probability density function of the ocean waves from radar observations by d hauser et al 1 intermediate scale waves isw about 0 02 to 6 m long are the main contributor of the ocean surface roughness relevant to passive and active microwave remote sensing of the ocean while wind speed is the most important parameter determining the spectral composition of the ocean surface roughness analysis of field measurements indicates that the wave spectrum of isw is strongly modified by background waves the mean square slope derived from the wave spectrum is therefore also modified by the background wave condition investigation of ocean surface roughness without taking into account the sea state parameter can lead to incorrect conclusions 2 the paper by hauser et al 2008 hereinafter referred to as hcgm08 presented very interesting results on the properties of ocean surface roughness derived from c band 5 35 ghz radar observations they compared the filtered mean square slope obtained under the assumption of gaussian probability density function pdf of surface slopes with three published spectral models their interpretation of the empirical spectral model of hwang 2005 hereinafter referred to as h05 is inaccurate as a result they attributed the disagreement between their data with h05 to the discontinuity in the h05 spectrum caused by matching the empirically parameterized intermediate scale wave isw spectrum and an assumed equilibrium spectrum for the longer waves the issue of matching will be further discussed in section 2 their description on the comparison with h05 was verbal hcgm08 p 9 the result is shown in figure 1 here the analyses of hcgm08 produced two sets of mean square slope mss as a function of wind speed based on the assumption of gaussian shown in their figure 6d and nongaussian their figure 11b surface slope pdf they have noticed the large difference between the two sets of mss but no further comment or explanation was offered derivation of ocean surface roughness from radar backscattering cross section is a complex topic extensive discussions on the subject have been given in earlier publications e g jackson et al 1992 walsh et al 1998 results of mss computation using essentially the same approach of hcgm08 by jackson et al 1992 for ku band 14 ghz andwalsh et al 1998 for ka band 36 ghz are also shown in figure 1 together with the sun glitter data of cox and munk 1954 and the filtered mss of h05 spectral model integrated to an upper cutoff wave number kc suggested by jackson et al 1992 this cutoff wave number corresponds to surface wavelength about 4 7 times the radar wavelength the cutoff wave number used by hcgm08 is much higher corresponding to surface wavelength about 2 2 times the radar wavelength for their c band radar frequency 5 35 ghz kc is 24 rad m on the basis of the criterion of jackson et al 1992 and 51 rad m on the basis of hcgm08 also shown in their figure 1 are the filtered mean square slope derived from direct inversion of the backscattering cross section of ka band radar reported by vandemark et al 2004 further discussion of these data is deferred to section 3 3 after a close examination of their experimental conditions it becomes clear that the source of disagreement is quite different from that suggested by hauser et al and the hint was in fact given in h05 that is the mean square slope of the ocean surface is significantly modified by background waves hcgm08 did not provide too much information about the wind and wave conditions of their experiment however on the basis of the tabulated data presented in an earlier paper of the same experiment mouche et al 2005 the wavefields are strongly influenced by swell not related to the local wind condition in contrast the database used in constructing the h05 spectrum is wind sea dominant with mild swell presence section3 because radar remote sensingplays an increasingly more important role in oceanographic research and environmental monitoring and that an accurate interpretation of the remote sensing measurement requires a correct understanding of the ocean surface roughness in response to various geophysical parameters of interest such as wind air sea stability condition waves of various scales and currents of various sources a clarification of the properties of the ocean surface roughness spectrum is important i hope this note serves to correct the misinterpretation given by hauser et al 2008 regarding the ocean surface roughness spectrum and to call attention the important role of a missing parameter the background wave condition in their analysis

composition and fate of terrigenous organic matter along the arctic land ocean continuum in east siberia insights from biomarkers and carbon isotopes abstract climate warming is predicted to translocate terrigenous organic carbon terroc to the arctic ocean and affect the marine biogeochemistry at high latitudes the magnitude of this translocation is currently unknown so is the climate response the fate of the remobilized terroc across the arctic shelves represents an unconstrained component of this feedback the present study investigated the fate of permafrost carbon along the land ocean continuum by characterizing the terroc composition in three different terrestrial carbon pools from siberian permafrost surface organic rich horizon mineral soil active layer and ice complex deposit and marine sediments collected on the extensive east siberian arctic shelf esas high levels of lignin phenols and cutin acids were measured in all terrestrial samples analyzed indicating that these compounds can be used to trace the heterogeneous terrigenous material entering the arctic ocean in esas sediments comparison of these terrigenous biomarkers with other terroc proxies bulk 13c 14c and hmw lipid biomarkers highlighted contrasting across shelf trends these differences could indicate that terroc in the esas is made up of several pools that exhibit contrasting reactivity toward oxidation during the transport in this reactive spectrum lignin is the most reactive decreasing up to three orders of magnitude from the inner to the outer shelf while the decrease of hmw wax lipid biomarkers was considerably less pronounced alternatively degradation might be negligible while sediment sorting during the across shelf transport could be the major physical forcing that redistributes different terroc pools characterized by different matrix association despite the marked decrease shown by lignin the fingerprint of lignin phenols such as the acid aldehyde ratio of vanillyl and syringyl phenols showed a lack of any across shelf trends and exhibited an extremely wide range of values in all terrestrial samples by contrast the 3 5 dihydroxybenzoic vanillyl phenols ratio exhibited a clear across shelf trend suggesting either increasing degradation with distance from the coast or terroc sorting along the sediment dispersal system the ratio of syringyl vanillyl phenols indicated that gymnosperm tissues are more important than angiosperm tissues in surface sediments in particular off the lena river mouth consistent with the vegetation in its watershed conversely the fingerprint of p hydroxybenzenes suggests lack of substantial input of moss derived material finally autochthonous lipid and protein derived cuo reaction products displayed a strong along shelf gradient likely reflecting the inflow of nutrient rich pacific waters from the bering strait that stimulate primary productivity in the eastern esas in particular short chain fatty acids showed a clear frontal transition zone between pacific influenced and river influenced waters approximately along the 160 e longitude considering the labile nature of phytoplankton priming and co metabolism processes might stimulate degradation of terroc in the easternmost region of the siberian shelf this study demonstrated the need to consider multiple terroc proxies at isotopic molecular levels to differentiate the fate for different allocthonous components in arctic sediments and the need to assess how these terroc pools are distributed in different density size and settling fractions to better discriminate between the extent of hydrodynamic sorting versus degradation

paleontological records indicate the occurrence of open woodlands in a dry inland climate at the present day arctic coast in western beringia during the last interglacial abstract permafrost records accessible at outcrops along the coast of oyogos yar at the dmitry laptev strait ne siberia provide unique insights into the environmental history of western beringia during the last interglacial the remains of terrestrial and freshwater organisms including plants coleopterans chironomids cladocerans ostracods and molluscs have been preserved in the frozen deposits of a shallow paleo lake and indicate a boreal climate at the present day arctic mainland coast during the last interglacial terrestrial beetle and plant remains suggest the former existence of open forest tundra with larch larix dahurica tree alder alnus incana birch and alder shrubs duschekia fruticosa betula fruticosa betula divaricata betula nana interspersed with patches of steppe and meadows consequently the tree line was shifted to at least 270 km north of its current position aquatic organisms such as chironomids cladocerans ostracods molluscs and hydrophytes indicate the formation of a shallow lake as the result of thermokarst processes steppe plants and beetles suggest low net precipitation littoral pioneer plants and chironomids indicate intense lake level fluctuations due to high evaporation many of the organisms are thermophilous indicating a mean air temperature of the warmest month that was greater than 13 c which is above the minimum requirements for tree growth these temperatures are in contrast to the modern values of less than 4 c in the study area the terrestrial and freshwater organism remains were found at a coastal exposure that was only 3 5 m above sea level and in a position where they should have been under sea during the last interglacial when the global sea level was 6 10 m higher than the current levels the results suggest that during the last warm stage the site was inland and its modern coastal situation is the result of tectonic subsidence

quantitative interpretation of fossil pollen spectra dissimilarity coefficients and the method of modern analogs abstract dissimilarity coefficients measure the difference between multivariate samples and provide a quantitative aid to the identification of modern analogs for fossil pollen samples how eight coefficients responded to differences among modern pollen samples from eastern north america was tested these coefficients represent three different classes 1 unweighted coefficients that are most strongly influenced by large valued pollen types 2 equal weight coefficients that weight all pollen types equally but can be too sensitive to variations among rare types and 3 signal0to noise coefficients that are intermediate in their weighting of pollen types the studies with modern pollen allowed definition of critical values for each coefficient which when not exceeded indicate that two pollen samples originate from the same vegetation region dissimilarity coefficients were used to compare modern and fossil pollen samples and modern samples so similar to fossil samples were found that most of three late quaternary pollen diagrams could be reconstructed by substituting modern samples for fossil samples when the coefficients indicated that the fossil spectra had no modern analogs then the reconstructed diagrams did not match all aspects of the originals no modern analogs existed for samples from before 9300 yr b p at kirchner marsh minnesota and from before 11 000 yr b p at wintergreen lake michigan but modern analogs existed for almost all holocene samples from these two sites and brandreth bog new york

scattering of gps signals from the ocean with wind remote sensing application a theoretical model that describes the power of a scattered global positioning system gps signal as a function of geometrical and environmental parameters has been developed this model is based on a bistatic radar equation derived using the geometric optics limit of the kirchhoff approximation the waveform i e the time delayed power obtained in the delay mapping technique depends on a wave slope probability density function which in turn depends on wind waveforms obtained for aircraft altitudes and velocities indicate that altitudes within the interval 5 15 km are the best for inferring wind speed in some regimes an analytical solution for the bistatic radar equation is possible this solution allows converting trailing edges of waveforms into a set of straight lines which could be convenient for wind retrieval a transition to satellite altitudes together with satellite velocities makes the peak power reduction and the doppler spreading effect a significant problem for wind retrieval based on the delay mapping technique at the same time different time delays and different doppler shifts of the scattered gps signal could form relatively small spatial cells on sea surface suggesting mapping of the wave slope probability distribution in a synthetic aperture radar sar fashion this may allow more accurate measurements of wind velocity and wind direction

northern hemisphere controls on tropical southeast african climate during the past 60 000 years the processes that control climate in the tropics are poorly understood we applied compound specific hydrogen isotopes d and the tex86 tetraether index of 86 carbon atoms temperature proxy to sediment cores from lake tanganyika to independently reconstruct precipitation and temperature variations during the past 60 000 years tanganyika temperatures follow northern hemisphere insolation and indicate that warming in tropical southeast africa during the last glacial termination began to increase 3000 years before atmospheric carbon dioxide concentrations d data show that this region experienced abrupt changes in hydrology coeval with orbital and millennial scale events recorded in northern hemisphere monsoonal climate records this implies that precipitation in tropical southeast africa is more strongly controlled by changes in indian ocean sea surface temperatures and the winter indian monsoon than by migration of the intertropical convergence zone

forest or no forest implications of the vegetation record for climatic stability in western beringia during oxygen isotope stage 3 abstract two conflicting stratigraphic schemes describe the siberian karginskii interstade oxygen isotope stage 3 equivalent as having 1 relatively stable climate with environments more similar to the full glaciation or 2 variable climate with landscapes that more closely approximate contemporary ones new data from continuous lake cores and a nearly continuous section from western beringia wb suggest that both schemes are valid herb dominated communities possibly with isolated populations of larix characterized northern wb with only a slight shift from relatively warm to cool summers during the mid interstade in contrast herb and shrub tundra steppe forest tundra and modern larix forest occurred at various times in areas of southern wb suggesting greater climatic instability a thermal optimum is evident in the south during the mid interstade with modern vegetation in southeastern wb and larix forest tundra in the southwest variations in pinus pumila pollen indicate summer warm winter dry and summer warm winter wet conditions in southeastern wb these fluctuations contrast to other areas of wb where summers and probably winters were consistently arid although the interstade presents a unique interval within the late pleistocene paleodata and paleoclimatic models suggest that changes in marine conditions including sea level were likely key drivers in the regional climate history

a 35 kyr record of organic matter composition and δ13c of n alkanes in bog sediments close to lake baikal implications for paleoenvironmental studies abstract we characterized the compositions of organic compounds in a cheremushka bog sediment core deposited over the last 35 kyr located at the eastern coast of lake baikal to obtain basic information about the terrestrial organic matter om which contributed to lake baikal sediments the bog sediment was analyzed for the molecular composition of n alkanes lignin phenols and n c 24 to c 30 alkanoic acids as well as the carbon isotopic composition of plant wax derived n c 27 to c 33 alkanes concentrations of lignin phenols vanillyl v plus syringyl s phenols normalized to total organic carbon toc in the holocene are twice those for the last glacial maximum lgm while concentrations of toc normalized n c 24 to c 30 alkanoic acids do not change markedly in this period thus the ratio of lignin phenols to n c 24 to c 30 alkanoic acids increases from the lgm to the holocene this result is essentially consistent with pollen analysis indicating an expansion of woody plants in the holocene and a prevailing herb abundant environment for the lgm the 13 c values of n c 27 to c 33 alkanes e g 29 to 33 for c 31 indicate the presence of c 3 dominant plants throughout the core the contribution of terrestrial om to lake baikal sediments was estimated using the biomarkers on the assumption that the om in the bog sediments is a representative of the terrestrial om around the lake hence the estimation using lignin phenol or n c 24 to c 30 alkanoic acid parameters indicates that 11 24 of the toc in the academician ridge sediments is land derived for both the holocene and the lgm which is similar to the estimates from c n values of bulk om however the estimates for terrestrial om using the n c 27 to c 33 alkane parameter are generally higher than those using lignin phenol or n c 24 to c 30 alkanoic acid parameters the difference is thought to be associated with the difference in source and behavior of these biomarkers

stable vegetation and environmental conditions during the last glacial maximum new results from lake kotokel lake baikal region southern siberia russia abstract this paper presents a new decadal resolution fossil pollen record from lake kotokel 52 47 n 108 07 e 458 m a s l and provides a reconstruction of the last glacial maximum lgm vegetation and environments in the study area during this interval of globally harsh climate lake kotokel is situated close to the eastern shoreline of lake baikal in the boreal forest zone of southern siberia the analysed 190 cm long section 6 of the bottom core ktk10 ktk10 6 consists of compact undisturbed greenish grey to dark grey slightly laminated silty clay indicating continuous lacustrine sedimentation throughout the lgm period ca 26 8 19 1 cal ka bp the age model is supported by 11 calibrated ams dates the results of pollen analysis and pollen based biome reconstruction show that steppe and tundra vegetation composed of grasses and various herbs dominated ca 26 8 19 1 cal ka bp occurrence of conifer tracheids and stomata throughout the record together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen suggests the presence of single trees or small forest stands in the lake vicinity most likely in the river valleys application of the biomisation method and the resulting numerical scores of the most characteristic biomes steppe tundra and cold deciduous forest show minor fluctuations signifying stability of the regional vegetation cover during the analysed lgm interval in contrast to the regional biomes the local environmental indicators demonstrate greater sensitivity of the lake system to decadal and century scale climate variability the highest pollen percentages of ranunculaceae representing littoral meadow vegetation communities are registered ca 23 8 23 4 cal ka bp this and an increase in coarse grained sand particles together with slightly increased total inorganic carbon tic values representing calcite in the ktk10 6 sediment provide evidence of a much shorter than present distance between the coring site and the shoreline and a reduced lake area in line with a drier than present lgm climate a general stability of the grassland vegetation in the study region ca 26 8 19 1 cal ka bp and relatively constant total organic carbon toc values support the hypothesis that this productive vegetation could stably serve as a perennial food resource for large populations of herbivores thus providing favourable environments for the local hunter gatherers inhabiting the lake baikal region during the lgm interval

palaeoecological and experimental evidence of former forests and woodlands in the treeless desert pastures of southern tibet lhasa a r xizang china abstract palaeoecological and palaeopedological investigations around lhasa 3650 m 29 40 n 91 04 e a r xizang china provide evidence of human induced environmental changes which have occurred over the past 4600 years the present desert pastures of southern tibet most probably replaced forests of juniperus convallium j tibetica and cupressus gigantea along with prunus mira and buddleja crispa in the understorey paleosol investigations and determined charcoal indicate a likeliness of forest destruction followed by increased erosion and sedimentation of colluvial soils for the first time cereal pollen types could be clearly distinguished in southern tibet juniperus pollen has been proved to have only a short dispersal range the presence of cereal pollen and other human indicator pollen proves that it is more likely that human activity rather than climatic changes caused the forest decline during the younger holocene successful non irrigated reforestation trial experiments since 1997 on southern slopes around lhasa with indigenous cupressaceae have demonstrated that desertification of southern tibet is a reversible process as lhasa receives 443 mm annual precipitation and has summer temperatures of above 10 c it follows that the natural vegetation should be a forest as opposed to the desert status quo that presides at present

holocene paleoenvironmental records from nikolay lake lena river delta arctic russia radiocarbon dated pollen rhizopod chironomid and total organic carbon toc records from nikolay lake 73 20 n 124 12 e and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the holocene in the lena delta area shrubby alnus fruticosa and betula exilis tundra existed during 10 300 4800 cal yr bp and gradually disappeared after that time climate reconstructions based on the pollen and chironomid records suggest that the climate during ca 10 300 9200 cal yr bp was up to 2 3 c warmer than the present day pollen based reconstructions show that the climate was relatively warm during 9200 6000 cal yr bp and rather unstable between ca 5800 3700 cal yr bp both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modern day conditions after ca 3600 cal yr bp the chironomid based temperature reconstruction suggests a relatively warm period between ca 2300 and 1400 cal yr bp which corresponds to the slightly warmer climate conditions reconstructed from the pollen modern chironomid and rhizopod assemblages were established after ca 1400 cal yr bp

quantitative reconstruction of the last interglacial vegetation and climate based on the pollen record from lake baikal russia changes in mean temperature of the coldest t c and warmest month t w annual precipitation p ann and moisture index were reconstructed from a continuous pollen record from lake baikal russia the pollen sequence con01 603 2 53 57 n 108 54 e was recovered from a 386 m water depth in the continent ridge and dated to ca 130 114 8 ky bp this time interval covers the complete last interglacial li corresponding to mis 5e results of pollen analysis and pollen based quantitative biome reconstruction show pronounced changes in the regional vegetation throughout the record shrubby tundra covered the area at the beginning of mis 5e ca 130 128 ky consistent with the end of the middle pleistocene glaciation the late glacial climate was characterised by low winter and summer temperatures t c 38 to 35 c and t w 11 13 c and low annual precipitation p ann 300 mm however the wide spread of tundra vegetation suggests rather moist environments associated with low temperatures and evaporation reconstructed 1 tundra was replaced by boreal conifer forest taiga by ca 128 ky bp suggesting a transition to the interglacial taiga dominant phase lasted until ca 117 4 ky bp e g about 10 ky the most favourable climate conditions occurred during the first half of the li p ann reached 500 mm soon after 128 ky bp however temperature changed more gradually maximum values of t c 20 c and t w 16 17 c are reconstructed from about 126 ky bp conditions became gradually colder after ca 121 ky bp t c dropped to 27 c and t w to 15 c by 119 5 ky bp the reconstructed increase in continentality was accompanied by a decrease in p ann to 400 420 mm however the climate was still humid enough 0 9 to support growth of boreal evergreen conifers a sharp turn towards a dry climate is reconstructed after ca 118 ky bp causing retreat of forest and spread of cool grass shrub communities cool steppe dominated the vegetation in the area between ca 117 5 ky and 114 8 ky bp suggesting the end of the interglacial and transition to the last glacial mis 5d shift to the new glaciation was characterised by cool and very dry conditions with t c 28 to 30 c t w 14 15 c p ann 250 mm and 0 5

reconstruction of postglacial to early holocene vegetation history in terrestrial central europe via cuticular lipid biomarkers and pollen records from lake sediments high resolution environmental reconstruction for central european terrestrial settings is commonly based on sediment records that provide the pollen spectra used for reconstruction of vegetation development alternatively complementary algal insect or zooplankton assemblages and or carbonate 18 o isotope profiles are investigated in this study vegetation development and inferred climate evolution were documented on a decadal to centennial scale by analysis of land plant cuticular lipids accumulated in lake sediments wax lipids derived from land plant leaves and blades are source diagnostic and highly resistant to degradation their aerodynamic properties favor short distance eolian transport but they are less affected by possible long distance transportation that complicates pollen analysis the late glacial to holocene sedimentary record of lake steisslingen southwestern germany was investigated by palynological and geochemical means tundra type pioneer vegetation consisting predominantly of grasses and herbs is dominated by nc31 alkanes whereas pioneer birch forest yields preferentially nc27 alkanes establishment of a pine assemblage is recognizable by elevated nc29 and nc31 leaf wax alkanes and the diversification of deciduous forests in the holocene is marked by nc29 dominance lipid geochemistry and palynology resolve decadal excursions such as the mid younger dryas event centennial climate trends with pronounced and rapid changes at the oldest dryas bolling allerod younger dryas and younger dryas preboreal transitions are consistently reflected by molecular and palynological proxy data the demonstrated suitability of an independent molecular proxy in paleoenvironmental studies provides new perspectives in high resolution climate reconstruction

late pleistocene and holocene vegetation and climate records from lake kotokel central baikal region abstract climatically driven late pleistocene and holocene vegetation changes were reconstructed based on pollen records from the sediments of lake kotokel and cheremushka bog located on the eastern shore of lake baikal the described paleoenvironmental record has higher resolution than records collected from lake baikal and unites individual events identified in prior studies of bottom and onshore cores remarkable shifts in landscapes and expansions of index plants are as follows forest tundra and or forest steppe landscape with birch spruce artemisia and poaceae prevailed at ca 50 25 14 c kyr bp tundra and or steppe vegetation dominated by artemisia and poaceae was typical for the last glacial maximum the expansion of shrub birch and willow occurred at ca 15 5 14 c kyr bp two peaks of spruce expansion at ca 47 5 42 4 14 c kyr bp karginian time and at ca 14 5 13 ka bolling allerod warm intervals suggest that the condition were more humid than today a slight increase in artemisia at ca 11 10 5 14 c kyr bp 13 12 ka was indicative of the younger dryas event an expansion of birch forests with fir at ca 12 6 4 ka suggests higher humidity the currently dominant scots and siberian pine forests with birch expanded since 6 4 ka

quasi gaussian probability density function of sea wave slopes from near nadir ku band radar observations abstract although in most circumstances sea wave slope probability density function pdf is expressed as gaussian distribution there is evidence that it follows quasi gaussian distribution which can be represented by gram charlier series to fourth order all the statistical parameters of slope pdf have previously been derived by using optical methods in specular conditions and values and relationships with surface parameters have been presented in the literature however they may not be relevant at microwave wavelengths due to diffraction effects up to now sea surface slope pdf consistent with ocean microwave remote sensing is not known yet so it is important to establish the parameter models of quasi gaussian slope pdf compatible with radar application in this paper based on the backscattering coefficients from the ku band space borne radar precipitation radar pr data all the parameters of the quasi gaussian slope pdf are inverted using a so called go4 boisot et al 2015 model with a two dimensional 2 d non linear least square fit on the backscattering coefficients we also establish the empirical formulae relating the statistical parameters of the quasi gaussian sea slope pdf with wind speed which may be used for ocean ku band radar application the proposed empirical formulae are compared to the cox and munk 1954 cm slope parameter model the results confirm that the slope variance in upwind and crosswind directions as well as the skewness coefficients exhibit intermediate values between the cm slope parameters of clean surface and slick surface cases the coefficients of peakedness are just in the range of the cm slope peakedness parameter values the impacts of wave conditions swell or wind sea on slope pdf parameters are also studied the results show that in most wind speed conditions the presence of swell increases the skewness coefficients while it decreases the peakedness coefficients

petrogenesis of cretaceous granitoids in the bengbu wuhe area southeastern north china craton implications for gold mineralization abstract sinistral slip along the tancheng lujiang fault zone tlfz during the mesozoic resulted in an offset of approximately 400 km between the dabie and sulu orogens the bengbu wuhe gold belt bwgb represents an extension of the zhaoyuan yexian gold belt to the west of the tlfz early cretaceous intrusions are widely distributed throughout the bwgb gold deposits in the bwgb are commonly associated with intermediate acid dykes that are roughly contemporaneous with mineralization and some orebodies are hosted in granitoids this paper investigates granitoids within the bwgb to constrain their petrogenesis tectonic setting and metallogenic significance using systematic whole rock elemental geochemistry apatite geochemistry zircon u pb dating zircon lu hf isotopes and whole rock sr nd and pb isotopes the timing of au mineralization 134 113 ma in the area is consistent with the age of intrusive adakite like rocks 130 115 ma and normal calc alkaline granitoids 114 109 ma the adakite like samples are characterized by pronounced enrichment in light rare earth elements ree depletion in heavy ree la yb n 30 5 66 2 an absence of eu anomalies high sr contents and sr y ratios low y and yb contents and fractionated ree patterns dy yb n 1 22 1 69 they have relatively low mg values 38 42 and variable sr nd pb hf isotopic compositions 87sr 86sr t 0 7083 0 7111 end t 22 2 to 14 9 206pb 204pb t 17 219 18 010 zircon ehf t 21 0 to 12 3 these features indicate that the parental magmas of the adakites were derived from partial melting of thickened lower crust of the south china plate and or the north china craton the normal calc alkaline granitoids have low sr y 6 0 40 5 la ybn 6 8 24 7 and dy ybn 0 90 1 28 ratios exhibit negative eu anomalies and have variable sr nd pb hf isotopic compositions 87sr 86sr t 0 7082 0 7085 end t 22 7 to 17 7 206pb 204pb t 16 686 16 713 zircon ehf t 24 9 to 19 0 indicating they were derived from the middle to lower crust of the north china craton compared with the normal calc alkaline granitoids the adakite like rocks have higher zircon ce4 ce3 higher apatite so3 and lower apatite mno contents lower and more variable zircon crystallization temperatures and higher apatite molar oh f and cl f ratios indicating that the adakitic magmas were more enriched in volatiles and more highly oxidized taken together field observations and geochemical data suggest that the adakite like rocks related to the subducted south china block are the ore causative rocks

evidence for late pleistocene climate changes from buried soils on the southern slopes of mt kilimanjaro tanzania abstract the distribution of the altitudinal vegetation zones on the slopes of mt kilimanjaro is well known but no reliable data are available about the vegetation shifts during the quaternary here i present palaeopedological results elemental biomarker stable isotope and radiocarbon analyses indicating that the frequently occurring buried black a horizons in the montane forest belt are developed under ericaceous vegetation since erica species are not abundant at this altitude nowadays but are characteristic for the sub alpine zone the palaeosols reflect palaeoclimatically driven fluctuations and changes of the vegetation zones on mt kilimanjaro the downhill descent of the ericaceous belt coincided with cold and dry periods like the late glacial and the last glacial maximum older palaeosols document that such events also took place during the marine isotope stages 3 and 4

the lateglacial and postglacial vegetation history of the northwestern limits of beringia based on pollen stomate and tree stump evidence abstract in order to reconstruct the late and postglacial vegetation history of the northwestern edge of beringia a sediment core was collected from a lake north of the present treeline along the lower lena river of northeastern siberia and analysed for fossil pollen and stomates in addition fossil tree stumps were collected in the vicinity of the lake eight radiocarbon dates indicate that the lake sediment record spans at least the past 12 300 yr bp the early vegetation at this site was dominated by herb and shrub tundra possible evidence of younger dryas cooling consisting of a decrease in shrub birch and increases in grass and herbaceous plants occurs between 11 000 and 10 000 yr bp forests dominated by larix dahurica and including picea obovata extended northward to the site between 8500 and 3500 yr bp there is an agreement between the pollen stomate and tree stump evidence for this advance the modern vegetation of shrub tundra was established after 3500 yr bp

quantitative pollen based climate reconstruction in central japan application to surface and late quaternary spectra abstract climate reconstruction in japan by the best modern analogues method was tested with 285 surface pollen spectra and then applied to the 47 000 years pollen profile from lake mikata central japan both pollen taxa percentages and plant functional type affinity scores were used in the reconstruction of six climate variables the reconstructed values were compared with the estimated modern climate at each surface pollen site in order to evaluate the accuracy of the pollen based reconstruction the reconstruction of thermal parameters is very reliable correlation coefficient r between 0 86 and 0 89 the reconstruction of annual precipitation is less accurate r 0 7 we also proposed a new technique to calibrate reconstructed values into both probability distribution and or confidence regions of observed values the specialized programs for this calibration polcalib and polhist are available at qsr website http www elsevier nl locate quascirev the reconstruction of the late quaternary climate changes around lake mikata shows that the summer and winter temperatures were 5 c lower than present around 40 uncal kyr bp reached a minimum around 20 uncal kyr bp 10 c lower than present and became similar to present day at 8 uncal kyr bp the estimates for annual precipitation show that it was driest around 20 uncal kyr bp

comparison of modeled and reconstructed changes in forest cover through the past 8000 years eurasian perspective reproducing the tree cover changes throughout the holocene is a challenge for land surface atmosphere models here results of a transient holocene simulation of the coupled climate carbon cycle model climber2 lpj driven by changes in orbital forcing are compared with pollen data and pollen based reconstructions for several regions of eurasia in terms of changes in tree fraction the decline in tr ee fraction in the high latitudes suggested by data and model simulations is driven by a decrease in summer temperature over the holocene the cooler and drier tr end at the eastern side of the eurasian continent in mongolia and china also led to a decrease in tree cover in both model and data in contrast the holocene trend towards a cooler climate in the continental interior kazakhstan is accompanied by an increase in woody cover ther e a relatively small reduction in precipitation was likely compensated by lower evapotranspiration in comparison to the monsoon affected regions in general the model data comparison demonstrates that climate driven changes during the holocene result in a non homogeneous pattern of tree cover change across the eurasian continent for the eifel region in germany the model suggests a relatively moist and cool climate and dense tree cover the holzmaar pollen r ecord agrees with the model for the intervals 8 3 ka and 1 7 1 3 ka bp but suggests great reduction of the tree cover 3 2 ka and after 1 3 ka bp when highly developed settlements and agriculture spread in the region

holocene treeline history and climate change across northern eurasia radiocarbon dated macrofossils are used to document holocene treeline history across northern russia including siberia boreal forest development in this region commenced by 10 000 yr b p over most of russia forest advanced to or near the current arctic coastline between 9000 and 7000 yr b p and retreated to its present position by between 4000 and 3000 yr b p forest establishment and retreat was roughly synchronous across most of northern russia treeline advance on the kola peninsula however appears to have occurred later than in other regions during the period of maximum forest extension the mean july temperatures along the northern coastline of russia may have been 2 5 to 7 0 c warmer than modern the development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions including heightened summer insolation the demise of eurasian ice sheets reduced sea ice cover greater continentality with eustatically lower sea level and extreme arctic penetration of warm north atlantic waters the late holocene retreat of eurasian treeline coincides with declining summer insolation cooling arctic waters and neoglaciation

comparison of model predictions with measurements of ku and ka band near nadir normalized radar cross sections of the sea surface from the genesis and rapid intensification processes experiment a comparison of model predictions with measurements of near nadir normalized radar cross sections nrcss of the sea surface at ku and ka bands is reported measurements of airborne precipitation radar second generation apr 2 from near nadir to 25 incidence angle along with simultaneous wind truth from dropsonde observations are compared with predictions of the cutoff invariant two scale model of sea scattering with the overall goal of assessing the model for possible future use in the apr 2 calibration process the performance of the model as a function of wind speed and incidence angle is therefore emphasized the measured data set acquired primarily during the 2010 genesis and rapid intensification processes grip experiment includes wind speeds from approximately 5 to 45 m s model comparisons are limited by uncertainties in the wind fields due to limited dropsonde coverage the data set is separated into more reliable containing wind speeds of 5 20 m s and less reliable wind speeds of 5 45 m s wind truth categories accordingly because a model of the sea spectrum is required for cutoff invariant model predictions comparisons with measured data are performed for three differing sea spectrum descriptions it is found that a bias of less than 1 db over the wind speed range 5 40 m s and a standard deviation less than 1 db over the wind speed range 10 40 m s can be achieved when using the unified sea spectrum description of elfouhaily the model also provides error levels that are near uniform with respect to both incidence angle and wind speed