quantitative reconstruction of mid to late holocene climate in ne china from peat cellulose stable oxygen and carbon isotope records and mechanistic models there has been an increasing need to reconstruct past climate from proxy records quantitatively and mechanistically the inverse proxy modeling method stands out as a novel approach to quantitative palaeoclimate reconstructions through integrating process based models and proxy records representing a major progress in quantitative palaeoclimatology it has been proposed to incorporate multiple proxy records to produce a more robust constraint on the climate parameters sought for estimation and most of the work has been conducted using pollen records in conjunction with vegetation models here i show a worked example of using paired stable oxygen and carbon isotope records of peat cellulose from one single core to infer the climate history in ne china for the last 6000 years through solving a well posed inverse problem using bayesian statistics the quantitative palaeoclimate data obtained in this study may deepen our insight into the dynamics of the east asian summer monsoon mean growing season temper

geochemical evolution of groundwater beneath mexico city abstract the geochemical evolution of groundwaters along a 24 km flow beneath central mexico city path from the sierra de las cruces towards lake texcoco has been investigated using stable isotopes radiocarbon and major and trace elements to determine the natural baseline conditions the extent of any contamination and the effectiveness of the overlying aquitard seal modern groundwaters of low salinity 1 are found up to 11 km from the outcrop area and groundwater ages of up to 6000 yr bp occur in the middle part of the section groundwater stable isotope ratios 18 o and 2 h lie close to the global meteoric water line indicating that the groundwater originates from local rainfall the groundwater chemistry may be interpreted as the result of inputs from the source area with progressive water rock interaction down the horizontal flow gradient a redox boundary is found at 9 km along the line of section coincident with the start of the confined section relatively low nitrate concentrations below 9 mg l 1 no 3 n are found in the aerobic waters low concentrations of no 3 in the aerobic waters and low cl reflect inputs prior to the modern development some elements cr u as se sb increase their concentration with distance time as far as the redox boundary but low concentrations occur in the reducing aquifer section the chemistry of several major ions mg na cl k as well as trace elements such as li rb ba reflect the weathering of the basaltic mineral assemblage feldspars and mafic minerals and their increases are generally proportional to residence time phosphate f and i concentrations indicate a probable source from apatite in the basaltic or rhyolitic rocks a borehole in the east of the city some 17 km downgradient intercepted thermal water si geothermometry indicates 163 c at depth this water gives a distinctive composition indicating possible addition of metamorphic co 2 which has then reacted with the igneous rocks increases in b and cl are derived from volatiles trapped in the glass or vesicular basalt a thermal anomaly found in the middle section of the heavily pumped aquifer is interpreted as the up coming of warmer water from medium to greater depth mainly from basalts rhyolites and possibly limestones the geochemistry indicates that groundwater beneath mexico city is of good quality and there is no obvious evidence of leakage of inorganic compounds from surface sources of contamination through the aquitard the younger groundwater drawn from the western outcrop area is generally of good inorganic quality increased drawdowns in the confined aquifer have induced flow of warmer water with higher cl from depth the resources in the aquifer represent an important reserve of good quality water which need to be properly managed as a high quality resource as part of integrated plans for the city s future supplies

holocene vegetation and climate history of the northern bighorn basin southern montana records of holocene vegetation and climate change at low elevations 2000 m are rare in the central rocky mountain region we developed a record of holocene vegetation and climate change from 55 14c dated woodrat middens at two low elevation sites 1275 to 1590 m currently vegetated by juniperus osteosperma woodlands in the northern bighorn basin macrofossil and pollen analyses show that the early holocene was cooler than today with warming and drying in the middle holocene during the holocene boreal juniperus communis j horizontalis and montane species j scopulorum were replaced by a great basin species j osteosperma j osteosperma colonized the east side of the pryor mountains 4700 14c yr b p downward movement of lower treeline indicates wetter conditions between 4400 and 2700 14c yr b p increased aridity after 2700 14c yr b p initiated expansion of j osteosperma from the east to west side of the pryor mountains

geostatistical analysis for spatially characterizing hydrochemical features of springs in taiwan the taiwan island is abundant in spring resources many industries of spring spas highlight unique hydrochemical characteristics of springs because consumers frequently consider bathing in all kinds of natural springs with therapeutic and relaxing functions this work adopted geostatistical approaches ordinary kriging ok and sequential gaussian simulation sgs to spatially explore hydrochemical features of springs in taiwan and establish classifications of springwater first ok and sgs were used to determine chloride sulfate and bicarbonate distributions of springs emerging from metamorphic and sedimentary rocks then ratios of chloride sulfate and bicarbonate equivalents per liter were calculated based on the determined distributions finally various combinations of chloride sulfate and bicarbonate were adopted to spatially characterize classifications of springwater this research result indicates that ok and sgs are capable of spatially characterizing the hydrochemical features and classification uncertainty of springs however the smooth effect of ok underestimates high values and overestimates low values reducing the difference among cl so42 and hco3 in springwater meanwhile sgs realizations not only present high spatial heterogeneity but enhance the influence of dominant hydrochemical features on classifications of springwater furthermore springwater emerging from metamorphic and sedimentary rock areas in taiwan can be divided into eight categories based on combinations of determined chloride sulfate and bicarbonate the principal hco3 water is the major springwater category the subordinate springwater types include the principal hco3 water with cl or hco3 and the principal cl water with hco3

biogeography of pleistocene conifer species from the ziegler reservoir fossil site snowmass village colorado article i nfo article history received 7 november 2013 available online xxxx pleistocene biogeography of conifer species is poorly known in much of western north america we conducted morphological studies on 201 conifer cones and cone fragments recovered from pleistocene sediments at the ziegler reservoir fossil site 2705 m near snowmass village colorado the basin formed 155 130 ka contains fossil bearing lacustrine palustrine and colluvial sediments spanning approximately 85 ka using a suite of mor phological characters particularlycone scale bracts we differentiated species of abies picea a ndpseudotsuga all fossil abies specimens were assignable based on bract morphology to abies concolor which is currently absent from central colorado nearest populations are 160 km southwest of the site a concolor occurs only in sedi ments of mis 5d and 5c pseudotsuga menziesii and picea engelmanniicones occurred in sediments corresponding to mis 5e 5d 5c and 5a a fourth conifer species occurring in sediments of mis 5e 5d 5c and 5a is difficult to assign to any extant species bract morphology is similar to picea pungens which grows near the site today but scale morphology is unlike p pungens these fossils may represent ancestral p pungens an extinct variant or an extinct sister species

the influence of lake morphometry on sediment focusing sediment focusing is a process whereby water turbulence moves sedimented material from shallower to deeper zones of a lake sediment focusing occurs in lakes in both the erosional coarse grained sediments and the transportational zone with the latter characterized by discontinuous sedimentation and resuspension the zone of accumulation is diefined as the zone where sedimentation is final i e no resuspension and where there is no further sediment focusing a geochemical tracer pb was used to trace sediment focusing patterns in 12 lakes of different morphomctries the area occupied by the zone of accumulation is predicted from the mean basin slope a with 86 of the variance explained only in large exposed lakes in which turbulence from waves is more severe are the resulting sediment distributions more erratic this study is the first to provide a general model of sc diment focusing patterns among lakes the study of lake bottom dynamics has received attention in the contexts of sediment contaminant and eutrophication studies the fact that sediments are major depositories for contaminants and nutrients has made them a focus for research in limnology also because sediments provide a record of past events in lakes an understanding of the manner in whllch sediments accumulate is essential for hindcasting interpretations of the historical record in sediments will be confounded if the record has been obscured by sediment resuspension the term sediment focusing was coined by likens and davis 1975 to describe the resuspension of sediments in shallower zones by waves and water currents with subsequent transport to and settling in the deeper zones of lakes much of the work

out of tune the dangers of aligning proxy archives abstract tuning is a widespread technique to combine date and interpret multiple fossil proxy archives through aligning supposedly synchronous events between the archives the approach will be reviewed by discussing a number of literature examples ranging from peat and tephra layers to orbital tuning and 18o series from marine and ice deposits potential problems will be highlighted such as the dangers of circular reasoning and unrecognised chronological uncertainties and some solutions suggested fossil proxy research could become enhanced if tuning were approached in a more quantitative reliable and objective way and especially if individual proxy archives were non tuned and kept on independent time scales

late quaternary vegetation history of rough canyon south central new mexico usa abstract south central new mexico usa at the junction of the rocky mountains high plains and chihuahuan desert is one of the better known regions in the late quaternary of north america plant macrofossils and pollen from a packrat midden series in rough canyon new mexico allows refinement of plant distributions and paleoclimates in this transitional area since full glacial times from 17 000 to 12 000 14c yr bp pinus edulis juniperus scopulorum woodlands dominated limestone substrates between 1800 and 1490 m with pseudotsuga menziesii and other mixed conifer species restricted to shady north facing slopes juniperus deppeana the dominant juniper today above 2000 m in southern new mexico is conspicuously absent from glacial middens and must have been displaced south of the us mexico border the minimum climatic conditions for p edulis j scopulorum woodlands are ca 20 wetter and 3 5 5 c cooler july mean maximum temperatures than the modern climate at rough canyon holocene warming drying may have started as early as 12 000 14c yr bp with the extirpation of j scopulorum from rough canyon and was completed by at least 10 54014c yr bp the record for arrivals of some desert species is confounded by traces of pollen and macrofossils in some of the glacial middens which could signify either earliest occurrence or temporal mixing contamination of assemblages ams 14c dating can discriminate between early arrival and contamination in midden macrofossils but not in pollen ams dates show that choisya dumosa presently near its northern cold limits at rough canyon endured late glacial winters possibly as clonal populations some larrea tridentata leaves and pollen occur in middens dominated by conifers and oaks no longer at the site an ams date of 3205 14c yr bp on larrea leaves from one midden indicates contamination evidence for some macrofossil contamination however does not rule out the possibility that pollen of desert elements e g larrea prosopis in late glacial early holocene middens indicates their presence in the tularosa basin well ahead of their local appearance in rough canyon finally the increasing dominance of desert elements after 5000 14c yr bp in the rough canyon series and elsewhere in the northern chihuahuan desert could reflect slow postglacial migration from the south and or progressive encroachment with gradual stripping of soils formed during the last glacial period

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

wellbore reservoir coupled simulation to study thermal and fluid processes in a co2 based geothermal system identifying favorable and unfavorable conditions in comparison with water using co2 as a heat transmission fluid to extract geothermal energy is currently considered as a way to achieve co2 resource utilization and geological sequestration as a novel heat transmission fluid the thermophysical properties of co2 are quite different from those of water co2 has many advantages such as larger mobility and buoyancy resulted from the lower density and viscosity this will reduce the consumption of pressure driving the circulation and save the energy of external equipment the cycle even can be achieved by siphon phenomenon under a negative circulating pressure difference however there are still some disadvantages for co2 as the heat transmission fluid such as small heat capacity leading to a less heat at the same mass flow rate at the same time because of the lager expansion and compression coefficient for co2 changes in temperature and pressure may cause a more complex flow and thermodynamic processes the lager compressibility makes it possible to get high temperature at the bottom of the injection well whereas the lager expansion coefficient makes the temperature drop rapidly along the production well therefore how to scientifically control the production pressure to guarantee sufficient high temperatures at the head of production well and thereby improve the efficiency of heat extraction are the key issues needed to be further addressed the geological and geothermal conditions correspond to the central depression of the songliao basin located in the northest of china this depression has a high geothermal gradient and heat flow in this article a classic idealized five spot reservoir model coupled with wellbores is used for simulations and analyses the objectives of the present work are 1 to investigate the fluid flow and thermal processes of supercritical co2 along the wellbore and in the reservoir 2 to understand the heat extracting mechanism 3 to identify advantages and disadvantages of using co2 as the heat transmission fluid and 4 to provide a theoretical basis for the selection of heat transmission fluid

vegetation response to southern california drought during the medieval climate anomaly and early little ice age ad 800 1600 abstract high resolution studies of pollen in laminated sediments deposited in santa barbara basin sbb core spr0901 02kc reflect decadal scale fluctuations in precipitation spanning the interval from ad 800 1600 from ad 800 1090 during the medieval climate anomaly mca sbb sediments were dominated by xeric vegetation types drought resistant coastal sagebrush and chaparral implying reduced precipitation in the southern california region drought adapted vegetation abruptly decreased at ad 1090 and was rapidly replaced by mesic oak quercus woodlands associated with an increased pollen flux into the basin after a mesic interval lasting 100 years pollen flux and the relative abundance of quercus pollen dropped abruptly at ad 1200 when the rapid rise of chaparral suggests a significant drought similar to that of the mca ad 800 1090 this brief resurgence of drought adapted vegetation between ad 1200 1270 marked the end of the mca droughts a gradual increase in mesic vegetation followed characterizing cool hydroclimates of the little ice age lia in coastal southern california the presence of xeric vegetation in sbb coincides with major drought events recorded in tree rings and low lake levels elsewhere in california except for the brief drought between ad 1130 1160 correlative diatom and terrigenous sediment input proxy records from sbb are largely supportive of the pollen record predominantly linking the mca with drought and la nina like conditions and the lia with wetter more el nino like conditions differences between paleoclimate proxies pollen diatoms and terrigenous sediment in sbb exist however possibly reflecting the temporal and spatial differences in the generation of each proxy record as well as their individual sensitivity to climate change

a geochemical traverse along the sperchios basin e evoikos gulf graben central greece origin and evolution of the emitted fluids the studied area is a 130 km long fast spreading graben in central greece its complex geodynamical setting includes both the presence of a subduction slab at depth responsible for the recent quaternary volcanic activity in the area and the western termination of a tectonic lineament of regional importance the north anatolian fault a high geothermal gradient is made evident by the presence of many thermal springs with temperatures from 19 to 82 c that discharge along the normal faults bordering the graben in the period 2004 2012 58 gas and 69 water samples were collected and their chemical and isotopic analysis revealed a wide range of compositions two main groups of thermal waters can be distinguished on the basis of their chemical composition the first represented by dilute waters e c 0 6 ms cm of the westernmost sites is characterised by the presence of ch4 rich and mixed n2 ch4 gases the second displays higher salinities e c from 12 to 56 ms cm due to mixing with a modified marine component reservoir temperatures of 150 160 c were estimated with cationic geothermometers at the easternmost sites along the graben from west to east the gas composition changes from ch4 to co2 dominated through mixed n2 ch4 and n2 co2 compositions while at the same time the he isotopic composition goes from typical crustal values 0 1 r ra up to 0 87 r ra showing in the easternmost sites a small 3 11 but significant mantle input the 13c values of the co2 rich samples suggest a mixed origin mantle and marine carbonates

the boron isotope systematics of the yellowstone national park wyoming hydrothermal system a reconnaissance abstract boron concentrations and isotope compositions have been measured in fourteen hot spring waters two drill hole waters an unaltered rhyolite flow and hydrothermally altered rhyolite from the geothermal system in yellowstone national park wyoming the samples are representative of the major thermal areas within the park and span the range of fluid types for the fluids the b concentrations range from 0 043 2 69 mm kg and the 11 b values range from 9 3 to 4 4 there is no relationship between the dissolved b concentrations or isotope compositions with the concentration of any major element other than cl or physical property each basin is characterized by a restricted range in b cl ratios and 11 b values hot spring waters from the morris basin upper geyser basin calcite springs and clearwater have 11 b values close to that of unaltered rhyolite 5 2 and are interpreted to have derived their b from this source waters from mammoth hot springs sheepeater and rainbow springs have lower 11 b values close to 8 these lower values may reflect leaching of b from sedimentary rocks outside the yellowstone caldera but they are similar to the 11 b value of hydrothermally altered rhyolite 9 7 hence the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals cooler springs along the yellowstone river just outside the park boundary have lower b concentrations and higher 11 b values that may reflect mixing with shallow meteoric water

vegetation and environment in eastern north america during the last glacial maximum abstract knowledge of the vegetation and environment of eastern north america during the last glacial maximum lgm is important to understanding postglacial vegetational and biogeographic dynamics assessing climate sensitivity and constraining and evaluating earth system models our understanding of lgm conditions in the region has been hampered by low site density problems of data quality particularly dating and the possibility that lgm vegetation and climate lacked modern analogs in order to generate improved reconstructions of lgm vegetation and environment we assembled pollen and plant macrofossil data from 21 and 17 well dated lgm sites respectively all sites have assemblages within the lgm timespan of 21 000 1500 calendar yr bp based on these data we prepared maps of isopolls macrofossil presence absence pollen analogs biomes inferred mean january and july temperatures and mean annual precipitation for the lgm tundra and open picea dominated forest grew along the laurentide ice sheet with tundra predominantly in the west in the east pinus dominated vegetation mainly p banksiana with local p resinosa and p strobus occurred extensively to 34 n and possibly as far south as 30 n picea glauca and a now extinct species p critchfieldii occurred locally picea dominated forest grew in the continental interior with temperate hardwoods quercus carya juglans liriodendron fagus ulmus growing locally near the lower mississippi valley at least as far north as 35 n picea critchfieldii was the dominant species in this region the florida peninsula was occupied by open vegetation with warm temperate species of pinus eastern texas was occupied by open vegetation with at least local quercus and picea extensive areas of peninsular florida and the continental interior had vegetation unmatched by any modern pollen samples the paleovegetational data indicate more extensive cooling in eastern north america at the lgm than simulated by either the ncar ccm0 or ccm1 climate models the occurrence of cool temperate conifers and hardwoods as far north as 34 35 n however indicates less severe cooling than some previous reconstructions paleoclimate inferences for the lgm are complicated by lowered atmospheric co 2 concentrations which may be responsible for the open nature and dominance of conifers in lgm vegetation

analysis of surface wind and roughness length evolution with fetch using a combination of airborne lidar and radar measurements 1 a combination of surface wind speed sws and sea state variables derived from quasi simultaneous airborne lidar and radar measurements made in the framework of the flux etat de mer et teledetection en condition de fetch variable fetch experiment is used to analyze the evolution of surface roughness length neutral drag coefficient and friction velocity coefficient with fetch in the first hundred kilometers offshore over the gulf of lion western mediterranean the study focuses on the tramontane mistral event documented in the afternoon of 24 march 1998 particular attention is given to sws derived from nadir lidar measurements the sws retrieval methodology developed and validated for open ocean conditions by flamant et al 1998 has been modified to account for the specificity of the coastal mediterranean environment complex mixture of continental and maritime aerosol turbid productive waters the lidar derived sws evolution with fetch observed on 24 march 1998 in the afternoon was validated against in situ and remote sensing measurements made from a buoy a ship as well as from the spaceborne altimeter topex the spatial variability in sws observed with the airborne lidar was controlled by the structure of the wake regions downstream of the massif central and the maritime alps delimiting the longitudinal extension of the mistral and was influenced by swell resulting from the action of a steady northeasterly flow coming from the ligurian sea in connection with intense alpine lee cyclogenesis these findings were supported by the other measurements it is further shown that based on a formulation of the dimensionless roughness dependance with wave age airborne lidar and radar measurements can be combined to provide insight into the evolution with fetch of roughness length neutral drag coefficient and friction velocity four distinct sea state regimes over a distance of 100 km could be identified from the remotely sensed variables obtained with this novel approach in connection with atmospheric forcing the dependance of lidar radar derived drag coefficient with lidar derived sws for the four regimes was found to be remarkably consistent with the relationship derived from the buoy measurements finally lidar radar derived friction velocities were found in good agreement with the buoy and in situ aircraft measurements

residence time indicators in groundwater the east midlands triassic sandstone aquifer the east midlands triassic sherwood sandstone aquifer which has been the subject of detailed radiometric age studies is used to investigate both inert and reactive constituents of groundwater as indicators of residence time detailed resampling of the aquifer in 1992 has provided a considerable body of new inorganic geochemistry data though without radiocarbon several inert indicators are defined including the isotopic ratios 18o 2h 36cl noble gas ratios as well as the halogen elements cl br f i and their element ratios these form a group of essentially unreactive tracers primarily reflecting changing rainfall inputs and palaeoclimatic conditions except at outcrop where human impacts are also seen clearly the concentrations of cl mainly from atmospheric sources remain below 25 mg l 1 cl over a distance of some 30 km from outcrop reactive indicators the result of time dependent water rock interactions include 13c mg ca sr ca na cl and show diagnostic trends along the flow lines however the concentrations of certain trace elements li rb cs mn and mo which are not limited by solubility constraints show linear trends along the present day flow gradient this water rock interaction is taking place in groundwaters with low total mineralisation and it can be demonstrated that reactions involving these elements and isotopes are occurring entirely within the aquifer since high salinity groundwaters are found below the sherwood sandstone there is good correlation between some of the elements and 14c activities in the 1977 data set and this has been used to derive a concentration age relationship for the 1992 set of data a chemical timescale for the aquifer is then established using a li and b a combination of five trace elements the age of the fresh groundwater is thus shown to be up to 100 ka bp indicating the likelihood of semi continuous recharge during the devensian glacial period preceding the glacial maximum when no recharge occurred 10 20 ka bp this approach may be of value in extending groundwater dating beyond the radiocarbon timescale as well as interpreting sites where no radiocarbon data are available the scatter from the mean age line indicates those groundwaters which are derived from either rapid or slower than average flow zones within the aquifer as well as age stratification this stratification is borne out by a depth profile of groundwater from a new borehole near to outcrop which is shown by a combination of chemical and isotopic tracers to contain holocene overlying late pleistocene water

alpine lee cyclogenesis influence on air sea heat exchanges and marine atmospheric boundary layer thermodynamics over the western mediterranean during a tramontane mistral event 1 data from a recent field campaign are used to analyze the nonstationary aspects of air sea heat exchanges and marine atmospheric boundary layer mabl thermodynamics over the gulf of lion gol in connection with synoptic forcing the data set includes measurements made from a wide range of platforms sea borne airborne and space borne as well as three dimensional atmospheric modeling the analysis focuses on the 24 march 1998 tramontane mistral event it is shown that the nonstationary nature of the wind regime over the gol was controlled by the multistage evolution of an alpine lee cyclone over the tyrrhenian sea between sardinia and continental italy in the early stage low at 1014 hpa the tramontane flow prevailed over the gol as the low deepened 1010 hpa the prevailing wind regime shifted to a well established mistral that peaked around 1200 utc in the afternoon the mistral was progressively disrupted by a strengthening outflow coming from the ligurian sea in response to the deepening low over the tyrrhenian sea 1008 hpa and the channelling induced by the presence of the apennine range italy and the alps in the evening the mistral was again well established over the gol as the depression continued to deepen 1002 hpa but moved to the southeast reducing the influence of outflow from the ligurian sea on the flow over the gol the air sea heat exchanges and the structure of the mabl over the gol were observed to differ significantly between the established mistral period and the disrupted mistral period in the latter period surface latent and sensible heat fluxes were reduced by a factor of 2 on average during that latter period air sea moisture exchanges were mainly driven by dynamics whereas during the former period both winds and vertical moisture gradients controlled moisture exchanges the mabl was shallower during the latter period 0 7 km instead of 1 2 km because of reduced surface turbulent heat fluxes and increased wind shear at the top of the mabl in connection with the outflow from the ligurian sea in the period of established mistral gravity waves above the mabl were observed to have an influence on the mabl structure in the perturbed mistral case this influence was not observed over the gol the ubiquitous presence of sheltered regions i e regions of reduced wind speed in the mabl in the lee of the three major mountain ranges surrounding the gol namely the pyrenees the massif central and the alps was shown to have an impact on surface turbulent heat fluxes the position of these sheltered regions which evolved with the synoptic conditions was the key to a correct interpretation of multiplatform surface turbulent flux measurements made over the gol on 24 march 1998

intrinsic vulnerability assessment of saturnia thermal aquifer by means of three parametric methods sintacs gods and cop three different parametric methods for the evaluation of intrinsic vulnerability to pollution have been applied in a hydrothermal carbonate aquifer located in central northern italy and the results obtained were compared with each other the study area large approximately 152 km2 lies in an area of the northern apennines the investigated aquifer feeds the hot thermal springs of saturnia the vulnerability assessment methods used are sintacs gods and cop the vulnerability maps obtained were first individually examined and then they were compared with each other by means of spatial analysis these maps show similar results for the estimation of the vulnerability just in some areas sintacs yields areas potentially vulnerable to pollution along the albegna river and its major tributaries in the northern part of the study area the gods index map reflects the great importance that this method gives to the lithological characteristics of the unsaturated zone in the subdivision of areas with different vulnerability gods and cop methods agree in classifying low vulnerability in the most part of central southern study area where the aquifer is confined by the pliocene clay deposits based on the conceptual model of groundwater flow developed for the aquifer under investigation cop seems the most appropriate method among those applied in this work in particular with regard to the assessment of the vulnerability of the recharge area of thermal groundwater located in the northern part of the study area where karst carbonate formations of the tuscan nappe outcrop this recharge area is classified by the cop method as highly vulnerable to pollution

the dependence of sea surface roughness on the height and steepness of the waves it is proposed that the sea surface roughness zo can be predicted from the height and steepness of the waves zo hs a hs lp b where hs and lp are the significant wave height and peak wavelength for the combined sea and swell spectrum best estimates for the coefficients are a 1200 b 4 5 the proposed formula is shown to predict well the magnitude and behavior of the drag coefficient as observed in wave tanks lakes and the open ocean thus reconciling observations that previously had appeared disparate indeed the formula suggests that changes in roughness due to limited duration or fetch are of order 10 or less thus all deep water pure windseas regardless of fetch or duration extract momentum from the air at a rate similar to that predicted for a fully developed sea this is confirmed using published field data for a wide range of conditions over lakes and coastal seas only for field data corresponding to extremely young waves u10 cp 3 were there appreciable differences between the predicted and observed roughness values the latter being larger on average significant changes in roughness may be caused by shoaling or by swell a large increase in roughness is predicted for shoaling waves if the depth is less than about 0 2lp the presence of swell in the open ocean acts on average to significantly decrease the effective wave steepness and hence the mean roughness compared to that for a pure windsea thus the predicted open ocean roughness is at most wind speeds significantly less than is observed for pure wind waves on lakes only at high wind speeds such that the windsea dominates the swell do the mean open ocean values reach those for a fully developed sea

boron sr o and h isotope geochemistry of groundwaters from mt etna sicily hydrologic implications combined b o h and sr isotopic studies of groundwaters from mt etna provide new constraints on their origin and the consequences of fluid rock interaction within this hydrologic system variations in d 18 o 29 7 to 27 2 and d d 262 to 223 mainly lie along the regional meteoric water line and suggest that most waters originated as local precipitation however small shifts in d 18 o and variable 87 sr 86 sr 0 70355 to 0 70879 and d 11 b 25 2 to 125 8 indicate that subsequent interactions occurred between the fluids and local rocks high b cl ratios in all samples seemingly preclude direct involvement of seawater in the hydrologic system despite the proximity to the coast and in some samples elevated 87 sr 86 sr and d 11 b two general end member water types are recognized on the basis of their chemistry these apparently are produced by interactions of local meteoric waters with the dominant reservoir rocks either basaltic lavas of etna or the underlying sediments respectively high d 11 b in the sediment hosted end member points to a significant marine carbonate contribution subsequent mixing between these or similar end members produced a range of intermediate composition groundwaters certain anomalous water compositions require the presence locally of a distinct component with high b and moderate d 11 b ca 110 but relatively low 87 sr 86 sr an anthropogenic source for this component is plausible one unusual sample has b and sr isotopic compositions similar to the other volcanic rock hosted waters but anomalously high cl content that likely reflects local magmatic outgassing near this sampling locality in general this study indicates that groundwater b and sr isotopic compositions are rock dominated these data provide useful constraints on the origin and evolution of groundwaters copyright 2000 elsevier science ltd

a case study of air sea interaction during swell conditions air sea interaction data from a situation with pronounced unidirectional swell have been analyzed measurements of turbulence at three levels 10 18 and 26 m above mean sea level together with directional wave buoy data from the site ostergarnsholm in the baltic sea were used the situation which lasted for 48 hours appeared in the aftermath of a gale the wind direction during the swell situation turned slowly within a 90 sector both during the gale phase and the swell phase the over water fetch was 150 km the wind speed during the swell phase was typically 4 m s 1 during the swell phase a wind maximum near or below the lowest wind speed measuring level 10 m was observed the net momentum flux was very small resulting in cd values 0 7 10 3 throughout the lowest 26 m covered by the tower measurements turbulence intensities in all three components remained high despite the low value of the kinematic momentum flux u w resulting in a reduction of the correlation coefficient for the longitudinal and vertical velocity from its typical value around 0 35 to between 0 2 and 0 and with some positive values at the higher measuring levels appearing abruptly at wave age c0 u10 equal to 1 2 turbulence spectra of the horizontal components were shown not to scale with height above the water surface in contrast to vertical velocity spectra for which such a variation was observed in the low frequency range in addition spectral peaks in the horizontal wind spectra were found at a frequency as low as 10 3 hz from a comparison with results from a previous study it was concluded that this turbulence is of the inactive kind being brought down from the upper parts of the boundary layer by pressure transport

late wisconsinan vegetation and environment of the tunica hills region louisiana mississippi abstract pollen plant macrofossil and radiocarbon dating studies of seven exposures of fluvial sediments in the tunica hills region of southeastern louisiana and southwestern mississippi provide new information on late wisconsinan vegetation flora and environment of the region the assemblages date between 25 250 and 17 530 yr b p pollen and macrofossil assemblages are dominated by picea which comprises 40 70 of the pollen assemblages abies and larix pollen and macrofossils are absent in contrast to sites to the north in the central mississippi valley deciduous hardwoods quercus fagus fraxinus carya juglans nigra acer ulmus are minor components of both pollen and macrofossil assemblages radiocarbon dates of picea and quercus wood indicate that these two genera grew contemporaneously in the region regional upland forests were dominated by picea picea cones and cone fragments are not typical of any extant north american species and probably represent either an extinct species or an extinct variety or subspecies of picea glauca late wisconsinan climate of the region was cooler than present but not necessarily as cool as implied by p glauca or other boreal taxa

double the dates and go for bayes impacts of model choice dating density and quality on chronologies abstract reliable chronologies are essential for most quaternary studies but little is known about how age depth model choice as well as dating density and quality affect the precision and accuracy of chronologies a meta analysis suggests that most existing late quaternary studies contain fewer than one date per millennium and provide millennial scale precision at best we use existing and simulated sediment cores to estimate what dating density and quality are required to obtain accurate chronologies at a desired precision for many sites a doubling in dating density would significantly improve chronologies and thus their value for reconstructing and interpreting past environmental changes commonly used classical age depth models stop becoming more precise after a minimum dating density is reached but the precision of bayesian age depth models which take advantage of chronological ordering continues to improve with more dates our simulations show that classical age depth models severely underestimate uncertainty and are inaccurate at low dating densities and also perform poorly at high dating densities on the other hand bayesian age depth models provide more realistic precision estimates including at low to average dating densities and are much more robust against dating scatter and outliers indeed bayesian age depth models outperform classical ones at all tested dating densities qualities and time scales we recommend that chronologies should be produced using bayesian age depth models taking into account chronological ordering and based on a minimum of 2 dates per millennium

inferring local to regional changes in forest composition from holocene macrofossils and pollen of a small lake in central upper michigan abstract vegetational response to climatic change involves processes of population and community dynamics within local stands which scale up to landscape level changes in vegetation composition and broad scale changes in species distributions understanding these dynamics poses a critical challenge to paleoecological explanation because of the broad range of scales at which these dynamics take place and interact we present an 8600 year paleoecological record of local and regional changes in forest composition from a small 2 6 ha lake in central upper michigan plant macrofossils provide a spatially precise record of local forest composition while pollen data provide a spatially integrated record of regional vegetational changes temporal patterns among different macrofossil types within species show overall coherence indicating that changes in macrofossil abundance generally record changes in local tree abundance temporal patterns in macrofossil sequences correspond to patterns in pollen sequences indicating that local changes contributed to the large scale changes in the surrounding region the pollen and macrofossil records show nearly continuous turnover in vegetation composition throughout the past 8600 years the longest period without major compositional change was ca 1600 years and dynamics at multidecadal to multicentennial scales are observed during many periods coordinated application of temporally precise sequences of pollen and macrofossil data at multiple sites can support inferences concerning vegetation dynamics at multiple spatial and temporal scales and test mechanistic hypotheses

geochemical patterns and origin of alkaline thermal waters in central greece platystomo and smokovo areas this study investigates the origin and chemical composition of the thermal waters of platystomo and smokovo areas in central greece as well as any possible relationships of them to the neighboring geothermal fields located in the south eastern part of sperchios basin the correlations between different dissolved salts and the temperature indicate that the chemical composition of thermal waters are controlled by the mineral dissolution and the temperature the reactions due to co2 that originates possibly by diffusion from the geothermal fields of sperchios basin and the mixing of thermal waters with fresh groundwater from karst or shallow aquifers two major groups of waters are recognized on the basis of their chemistry thermal waters of na hco3 cl type and thermal waters mixed with fresh groundwater of ca mg na hco3 type all thermal waters of the study area are considered as modified by water rock interaction rainwater heated in depth and mixed in some cases with fresh groundwater when arriving to the surface trace elements present low concentrations lithium content suggests discrimination between the above two groups of waters boron geochemistry confirms all the above remarks boron concentration ranges from 60 g l 1 to 10 mg l 1 while all samples constant isotopic composition 11b 10 indicates leaching from rocks the positive correlation between the chemical elements and the temperature clearly indicates that much of the dissolved salts are derived from water rock interactions the application of geothermometers suggests that the reservoir temperature is around 100 110 c chalcedony temperatures are similar to the emergent temperatures and this is typical of convective waters in fault systems in normal thermal gradient areas

importance of the vertical component of groundwater flow a hydrogeochemical approach in the valley of san luis potosi mexico fractured volcanics exert a control on groundwater flow in the san luis potosi slp valley the chemical composition and temperature of water pumped from boreholes partially penetrating the fractured volcanics indicate that the produced water originates from an upward vertical flow most of the thermal groundwater has been detected in areas related to regional faults and lineaments intensive and uncontrolled pumping from the upper 14 of the aquifer total depth 1500 m causes the rise of water from a deep regional flow system that mixes with the shallower waters the deep waters contain high fluoride concentrations that contaminate the mixture and cause substantial health related effects the recharge controls on the regional flow system require further research however hydrogeochemical evidence supports the view that the origin of this recharge is limited to the western bounding sierra madre occidental higher levels of dissolved na li f and so4 2 derived from tertiary volcanics have been introduced into the exploited region the concentrations indicate lengthy and deep circulation flow li concentration was used as an indicator of groundwater residence time and therefore of the length of the groundwater flow path hydrogeochemical interpretation indicates the presence of three flow systems a shallow local one controlled by a clay layer that subcrops most of the valley floor an intermediate system in which water infiltrates just beyond the boundary of the clay layer and a deep regional system which originates outside the surface catchment the local and intermediate systems circulate through materials with comparatively low hydraulic conductivity low cl concentrations suggest rapid flow in the regional system concentrations of li and f can be used to calculate percentages of waters in mixtures of regional and intermediate flows concentrations of na ca2 and so4 2 appear to be controlled by water rock reactions uncontrolled pumping increases will tend to enhance fluoride concentration and its undesirable effects lack of management of aquifers in basins similar to the slp valley can result in groundwater contamination not only from surface anthropogenic sources but also from natural water rock interactions

toward forward modeling for paleoclimatic proxy signal calibration a case study with oxygen isotopic composition of tropical woods a forward model of the oxygen isotopic composition 18o of wood cellulose is parameterized for time series prediction in tropical environments and driven with meteorological data observed at la selva biological research station costa rica for 1985 2001 monthly resolution model results correlate modestly r 0 34 p 0 05 with observed isotopic data with higher correlation r 0 45 p 0 01 over the earliest 10 years of comparison and nonsignificant correlation over the most recent 6 years of record analysis of model output for la selva suggests that isotopic variations are strongly controlled by rainfall amount the model simulates an analogous but stronger than observed negative isotopic anomaly associated with positive july september rainfall anomalies during el nino southern oscillation enso warm phase event years simulated tree isotope data for the global tropics suggest that a network of well replicated data series from selected locations may resolve the large scale precipitation anomaly pattern associated with enso

the evolution of alkaline groundwaters in the continental intercalaire aquifer of the irhazer plain niger this paper discusses the hydrochemical evolution of groundwaters in the multilayer artesian aquifer of the continental intercalaire the mainly jurassic agadez dabla sandstones aquifer of northern niger isotopic and chemical changes in relation to the geological setting suggest that the increasing hco3 alkalinity of the groundwaters is caused by interaction of deep co2 with the aquifer matrix alteration of feldspars by co2 with a 13c value of 3 0 accounts for the observed alkalinity and isotopic and trends carbon 14 ages have been estimated for recent and holocene groundwaters which have a distinct stable isotopic 2h and 18o signature compared with 14c dead groundwaters from further west on the irhazer plain recharge temperatures estimated by analysis of noble gas contents show that the 14c dead waters were recharged under conditions cooler than present averages in the region possibly at the beginning of deglaciation 16 ka b p or during the period 23 30 ka b p trends in the hydrochemistry of u are related to the deep co2 alteration process radiogenic he contents increase along the flow direction and extremely high values occur in the proximity of u ores denitrification in the paleowaters of the irhazer was assessed by measurements of nitrogen argon ratios

source processes of the thermal waters from the phlegraean fields naples italy by means of the study of selected minor and trace elements distribution abstract the geochemical characteristics of hydrothermal waters from the phlegraean fields p f naples italy were analysed for minor and trace elements selectively mobilised in hydrothermal systems such as b f hg as pb and tl the water samples collected from a shallow aquifer likely to be fed by deeper fluids showed various geochemical features resulting from the mixing of three components 1 surface waters of meteoric origin 2 hot deep waters deriving from water rock interaction and including deep waters of marine origin 3 magmatic fluids rising from the local magma chamber lying a few kilometres below the town of pozzuoli this setting although very complex provides a reliable means of studying the distribution of the investigated trace elements in particular within the phlegraean area high contents of b 0 1 48 mg l f 0 5 8 mg l as 16 6050 g l and hg 0 7 232 g l were observed the levels of thallium in the springs close to solfatara about 7 g l were in line with those normally recorded in hydrothermal areas whereas high levels of this element up to 23 3 g l were identified in other wells of the study area lead 1 3 to 29 1 g l appears to be anomalous with respect to its normal content in groundwater about 1 g l owing to the presence of high density brines at depth which enhance the solubility of pb in volcanic rocks under hydrothermal conditions the distribution of the investigated trace elements in the phlegraean fields thermal area is probably related to the different ascent pathways of the fluids clearly apart from the influence exerted by anomalous thermal conditions each element shows a different behaviour depending on its geochemical affinity with mineral phases and as a consequence of the different enthalpy values which determine ion partitioning in gaseous phases based on geochemical evidences and on the distribution of minor and trace elements the source processes of the investigated hydrothermal waters were defined five main groups were identified 1 acid sulphate waters resulting from mixing of meteoric water with magmatic gases mainly h 2 s 2 high sulphate chloride waters from a deep reservoir located in the major upflow zone 3 waters associated with significant degassing of magmatic co 2 4 waters from a deep geothermal neutral chloride reservoir resulting from heating of marine water modified by water rock interaction processes 5 cold waters from the inner area influenced by low temperature water rock interaction processes

pollen and macrofossils from wisconsinan interstadial sediments in northeastern georgia pollen and plant macrofossil analyses and dating both tams and conventional 14 c of wetland sediments from the nodoroc site in the piedmont region of northeastern georgia identified two depositional episodes of interstadial ca 26 000 22 000 yr b p and mid to late holocene 3600 yr b p age interstadial pollen assemblages were dominated by pinus and quercus with carya picea and abies also present in significant amounts the interstadial assemblages had lower pinus and higher quercus pollen percentages than apparently contemporaneous assemblages from sites in the southern appalachians and coastal plain interstadial macrofossils included two needle morphotypes of pinus subgenus pinus possibly indicating local occurrence of two pinus species one of the needle morphotypes is consistent with pinus banksiana but other species cannot be ruled out comparison of conventional and tams 14c dates illustrates problems in obtaining accurate age models from wetlands and ponds characterized by shallow or fluctuating water levels low sedimentation rates and vegetation growing on the depositional surface

mapped plant macrofossil and pollen records of late quaternary vegetation change in eastern north america abstract macrofossil presence absence maps and isopoll maps in 3000 year intervals show how ranges and abundance maxima for 12 eastern north american tree and shrub taxa picea p glauca p mariana larix laricina abies balsamea tsuga canadensis pinus strobus p resinosa p banksiana betula papyrifera b alleghaniensis b series humiles have changed from the last glacial maximum to the present the macrofossil maps corroborate patterns shown by the isopoll maps and provide spatial detail and taxonomic resolution the macrofossils confirm the inference from pollen data that unglaciated southeastern north america was cooler during the last glacial maximum 18 and 15 ka than simulated by the cohmap experiments with the ncar ccm0 general circulation model the geographic distribution of macrofossil occurrences during the late glacial 12 and 9 ka indicate that migration lag of boreal species did not occur at regional to subcontinental scales and that pollen assemblages lacking modern analogs resulted from climate gradients lacking modern analogs early holocene 9 and 6 ka macrofossil maps show rapid northward expansion of tree species ranges into deglaciated regions the data also show modest contractions of northern range limits of temperate species and expansions of southern range limits of boreal species in response to cooling trends during the late holocene 3 and 0 ka comparison of modern macrofossil maps of nine of these taxa with corresponding range maps confirm that the macrofossils record the geographic ranges accurately comparison of the modern macrofossil maps with maps of tree growing stock volume shows that for some taxa abies tsuga macrofossil occurrences were most frequent in regions of maximum tree abundance comparison of modern isopoll maps with the modern range and growing stock volume maps indicate that in contrast to the macrofossil data the pollen data provide poorer resolution of range limits for most taxa but better indications of abundance maxima and minima within the ranges

the north american hydrologic cycle through the last deglaciation abstract while the climate evolution of north america during the last deglaciation has received considerable attention few detailed model data comparisons of the deglacial hydroclimate have been conducted at the continental scale here we use a transient climate simulation of the last deglaciation and a synthesis of hydroclimate proxies from across the continent to broadly assess the moisture budget and its evolution including the primary components and mechanisms for changes and evaluate the level of agreement between model and data in order to inform areas of major discrepancy for attention in future work at the broadest scale the simulation indicates that north america was wetter than modern through much of the last deglaciation with the exception of the pacific northwest this was principally due to increased moisture convergence by the mean flow over the west of the continent and by transient eddies over the east we find that the simulation demonstrates considerable skill in comparison to proxy records in the coastal southwest and pacific northwest with limited success in other regions the highest disagreement occurs in the north central region where the model and data disagree on the sign of changes in addition we find that the areas of agreement coincide with regions whose hydroclimate is dominated by winter precipitation while regions of disagreement are those where summer precipitation is predominant and where the model suggests dynamical changes are important these results illustrate the impact of the ice sheet on the atmospheric dynamics and therefore the importance of its accurate reconstruction as well as that of model resolution our analysis and synthesis provide context for future transient climate simulations and suggest numerous areas of priority for future research

geochemical evidence of seawater intrusion into a coastal geothermal field of central greece example of the thermopylae system thermal water of thermopylae and from other geothermal fields located in the southern part of the sperchios basin central greece are characterized by high salinity total dissolved salts or tds range from 1 2 to 30 3 g l 1 associated with a degassing of co2 to determine the mineralization processes geochemical and isotopic investigations major elements 18o 2h and 13c have been carried out upon 17 thermal waters from springs and boreholes this study emphasizes that all the thermal waters result from the mixing of a seawater end member several fresh water components depending on the field location and a mantle derived co2 rising upward through an e w fault system the seawater identified in the thermal mixture is likely to be evolved aegean seawater asw once intruded into the basin sediments the trapped seawater has its chemical content modified by both water rock interactions and massive dissolution of the deep co2 pco2 of 100 5 atm the modelling performed with phreeqc indicates that the anomalous major ion ratios measured in the so called evolved asw are explained by the dissolution of calcite and dolomitization process associated to precipitation of gypsum within the thermal aquifer

geochemical constraints for the origin of thermal waters from western turkey the combined chemical composition b and sr isotopes and the basic geologic setting of geothermal systems from the menderes massif in western turkey have been investigated to evaluate the origin of the dissolved constituents and mechanisms of water rock interaction four types of thermal water are present 1 a na cl of marine origin 2 a na hco3 type with high co2 content that is associated with metamorphic rocks of the menderes massif 3 a na so4 type that is also associated with metamorphic rocks of the menderes massif with h2s addition and 4 a ca mg hco3 so4 type that results from interactions with carbonate rocks at shallow depths the na cl waters are further subdivided based on br cl ratios water from the cumali seferihisar and bodrum karaada systems are deep circulated seawater br cl sea water whereas water from canakkale tuzla br cl sea water are from dissolution of messinian evaporites good correlations between different dissolved salts and temperature indicate that the chemical composition of the thermal waters from non marine geothermal systems is controlled by 1 temperature dependent water rock interactions 2 intensification of reactions due to high dissolved co2 and possibly hcl gasses and 3 mixing with overlying cold groundwater all of the thermal water is enriched in b the b isotopic composition 11b 2 3 to 18 7 n 6 can indicate either leaching of b from the rocks or b oh 3 degassing flux from deep sources the large ranges in b concentrations in different rock types as well as in thermal waters from different systems suggest the water rock mechanism 87sr 86sr ratios of the thermal water are used to differentiate between solutes that have interacted with metamorphic rocks 87sr 86sr ratio as high as 0 719479 and carbonate rocks low 87sr 86sr ratio of 0 707864

the seben kesenozu low temperature geothermal prospect nw turkey study of an advective geothermal system the kesenozu thermal springs are located in northwestern turkey about 10 km south of seben the springs emerge from a fracture zone created by strike slip faulting that strikes north northwest along the hamambogazi creek in northwestern anatolia the reservoir comprises a steeply dipping fracture zone and deep feeding aquifers hosted by limestones and conglomerates of the kesenozu formation eight springs and one shallow well discharge thermal water at a total rate of about 44 l s with temperatures between 42 and 78 c the waters are of neutral ph nahco3 type the meteoric origin of the spa waters is evident from their chemical and isotopic 18o 2h 3h compositions the thermal system is driven by deep reaching advective flows where rainwater becomes heated on descent and after deep paths ascend along fractures that act as hydrothermal conduits it can be described as an advective geothermal system silica chalcedony geothermometry indicates equilibrium temperatures between 89 and 94 c a recently drilled deep well encountered similar temperatures at about 2 km depth the minimum heating power potential direct use of the fracture zone reservoir is about 10 mwth

representation of flora and vegetation in quaternary fossil assemblages known and unknown knowns and unknowns paleoecological inference rests on a foundation of processes and relationships that lie between the target variables of interest and the proxy data extracted from the fossil record inattention to these processes can lead to overconfidence reification of proxies and ignorance creep a process by which assumptions become taken for granted and ultimately hidden or forgotten paleoecological inference can be strengthened and its uncertainties identified and quantified by developing forward conceptual models that incorporate the processes and relationships known to lie between target variables and proxy data these may fall into four general categories source vector diagenesis and analysis the uncertainties within each of these categories are somewhat unique although interactions often arise among processes in different categories i use inference of regional species occurrence from macrofossil assemblages in woodrat neotoma middens to illustrate the effects of various processes and interactions on strength of inference and origin of uncertainties and to identify how uncertainties can be characterized reduced or quantified the kinds of issues discussed in the woodrat midden example are pervasive in paleoenvironmental and paleoecological inference and should be examined thoroughly for all proxies and archives on a regular basis

geochemical characteristics of greek thermal springs abstract a systematic sampling of all known thermal springs and gas emissions of continental greece has been carried out the main gas and water composition and some trace elements in liquid phase sio 2 h 3 bo 3 nh 4 and li have been determined the chemical composition of most thermal springs analyzed is typical of deep na hco 3 rising hot waters which circulate in co 2 rich silicic formations and which acquire progressively a na cl composition by admixing of colder shallower saline connate waters housed in the rock matrix of marine post orogenic tertiary quaternary sediments on the whole the thermal manifestations of continental greece can be fitted in a tectonic framework where high hydraulic gradients enable waters in hot deep aquifers to reach the surface rapidly along fault systems at the boundary of n s and e w trending tertiary basins equilibration temperatures of 80 120 c in the main storage zone 130 150 c max in the nestos xanthi basin have been assessed for most of the study area high n 2 and low h 2 and h 2 s content in gas emissions associated to water samples are consistent with temperatures assessed by using geothermometers in liquid phase

observation and modeling of the winter coastal oceanic circulation in the gulf of lion under wind conditions influenced by the continental orography fetch experiment 1 hydrological and currentmeter observations were collected on the continental shelf and slope of the gulf of lion during the fetch experiment 13 march to 15 april 1998 results from the first part of the cruise characterized by strong northern winds are presented the hydrological structures evidence well mixed water masses on the eastern and western ends of the shelf in the central part the situation is more complex with the influence of the rhone river s freshwater plume in the first 40 m of the water column and closer from the bottom with the confrontation of downwelled coastal cold water and upwelled warmer and saltier slope water current measurements show the path of the cyclonic circulation along the slope which is part of the general circulation of the western mediterranean and suggest the presence of large and temporary eddies on the shelf this oceanic circulation is simulated with a free surface three dimensional model using realistic forcing the model outputs are in agreement with the main hydrological and circulation patterns the results further indicate that coastal eddies are generated by the mesoscale structure of the wind field

hydrochemistry and isotope composition of springs in the tecopa basin southeastern california usa abstract springs and seeps in the tecopa basin were sampled and analyzed for their major ion chemistry and oxygen hydrogen and boron isotope compositions in order to assess the possible origins of the waters the tecopa basin is a groundwater discharge area along the amargosa river drainage basin south of the nevada test site and proposed high level nuclear waste repository at yucca mountain nv the spring waters are categorized into three end member hydrochemical facies 1 ph neutral na ca mg so4 hco3 water with moderate to high total dissolved solids 2 mildly alkaline na cl so4 hco3 water with high total dissolved solids and 3 alkaline na hco3 co3 water with high total dissolved solids the temperatures of most of the springs range from 17 c to 32 c however waters in the tecopa hot spring area range from 9 c to 47 c the oxygen and hydrogen isotope compositions normalized to smow of the waters are as follows the facies 1 springs have a mean 18o of 12 77 0 14 1 and d of 94 9 0 5 1 the facies 2 springs have a mean 18o of 12 73 0 19 1 and d of 97 7 0 9 1 the facies 3 spring has a mean 18o of 13 09 0 17 1 and d of 103 5 0 7 1 the mean boron concentrations and isotope compositions range from 2 4 mg l and 11b of 2 5 for facies 1 springs to 72 8 mg l and 11b of 3 8 for the facies 3 spring the facies 1 waters have chemical and isotope compositions consistent with meteoric recharge in the spring mountains nv groundwater flow through the regional carbonate aquifer and minor mixing with more concentrated water the thermal facies 2 waters are isotopically and chemically distinct from waters in the regional basin fill and carbonate aquifer systems these waters are interpreted to originate from fractured water bearing strata beneath the regional carbonate aquifer that discharge only in the southernmost part of the great basin the facies 3 spring is isotopically and chemically similar to basin fill aquifer waters in the amargosa desert but has higher sodium alkalinity and boron contents due to interaction with saline alkaline lake deposits of the plio pleistocene lake tecopa beds geologic geochemical and isotope data suggest that these three distinct water types flow through hydrogeologic compartments in the tecopa basin the compartments are interpreted to have been created by the impermeable lake tecopa beds and geologic structures within the basin

coefficients for sea surface wind stress heat flux and wind profiles as a function of wind speed and temperature surface layer coefficients for wind profiles wind stress and heat flux in typical open sea conditions are briefly reviewed businger dyer flux gradient relationships and a charnock wind stress formula fit the empirical data and are dimensionally consistent these have been solved by an iterative method and the results are presented in a tabular form suitable for climatological calculations from marine wind and temperature data

a 36 000 yr vegetation history from the peloncillo mountains southeastern arizona usa a 36 200 cal yr b p vegetation history was developed from macrofossils and pollen from 55 packrat middens from 1287 to 1442 m elevation in the peloncillo mountains of southeasternmost arizona usa today these elevations are dominated by semidesert grassland with a mixture of chihuahuan and sonoran desert shrubs including an eastern disjunct population of jojoba simmondsia chinensis from 36 200 to 15 410 cal yr b p rocky areas just above large pluvial lakes that occupied what are now dry playas supported pinus edulis juniperus osteosperma juniperus cf coahuilensis quercus cf turbinella and a rich understory of summer flowering c4 annuals and grasses indicating abundant summer rains and mild winters after 15 410 cal yr b p p edulis declined in abundance and disappeared briefly at 13 925 cal yr b p coincident with expansion of more xeric species and paleohydrological evidence for regional aridity during the bolling allerod warm interval p edulis rebounded briefly during the younger dryas at 12 405 cal yr b p before disappearing along with other mesic woodland species sometime after 12 100 cal yr b p the few middens dating from the early to middle holocene 10 000 4000 yr b p indicate wetter conditions than today at 7790 cal yr b p followed by a general drying trend the 35 middens from the late holocene detail the sequential arrival of desertscrub species as vegetation became more modern in character

an enhanced role for the tropical pacific on the humid pleistocene holocene transition in southwestern north america abstract climate effects on landscape evolution during the late pleistocene holocene transition 14 6 8 ka in southwestern north america traditionally are linked to the activity of the north american monsoon and to vegetation change related to a decrease in winter precipitation acting in response to orbital cyclicity we performed an integrated analysis of regional alluvial fan lacustrine and paleobotanical records for the area comparing them with hemispheric and regional paleoclimate proxies our focus was on the potential role the tropical pacific has as a synoptic pattern modulator and moisture source for hydrogeomorphic activity in the region our analysis indicates that the onset of alluvial fan aggradation in most of the region at 13 5 ka could have been a response to semi permanent el nino like conditions in the tropical pacific which enhanced the frequency of winter frontal storms as well as increased penetration of tropical cyclones in the region the north american monsoon was restricted in extent and intensity until 7 ka and probably was not a major factor in alluvial fan aggradation a second stage of alluvial fan aggradation from 11 5 to 9 ka was dominated by hyper concentrated flows and sheet flood sedimentation along with deposition in fluvial settings storms were probably were linked to landfall of enhanced water vapor bands in the leading edge of winter extra tropical cyclones with moisture advected directly from the tropical pacific at 8 ka favorable conditions for the occurrence of these storms waned and storm tracks shifted northward analysis of modern analogs for storm types described above as prevalent during this period indicates that changes in circulation patterns across the tropical pacific can affect storm properties enough to explain the observed geomorphic effects regardless of other factors traditionally considered of large impact like vegetation change our results suggest that the tropical pacific plays a larger role than currently thought in landscape evolution of the region

a forward modeling approach to paleoclimatic interpretation of tree ring data 1 we investigate the interpretation of tree ring data using the vaganov shashkin forward model of tree ring formation this model is derived from principles of conifer wood growth and explicitly incorporates a nonlinear daily timescale model of the multivariate environmental controls on tree ring growth the model results are shown to be robust with respect to primary moisture and temperature parameter choices when applied to the simulation of tree ring widths from north america and russia from the mann et al 1998 and vaganov et al 2006 data sets the forward model produces skill on annual and decadal timescales which is about the same as that achieved using classical dendrochronological statistical modeling techniques the forward model achieves this without site by site tuning as is performed in statistical modeling the results support the interpretation of this broad scale network of tree ring width chronologies primarily as climate proxies for use in statistical paleoclimatic field reconstructions and point to further applications in climate science

the fetch experiment an overview the flux etat de la mer et teledetection en conditions de fetch variable fetch was aimed at studying the physical processes associated with air sea exchanges and mesoscale oceanic circulation in a coastal region dominated by frequent strong offshore winds the experiment took place in march april 1998 in the northwestern mediterranean sea gulf of lion observations were collected with the r v l atalante with an air sea interaction spar asis buoy with waverider buoys and with research aircraft equipped for in situ and remote sensing measurements the present paper is an introduction to the following special section which groups 12 papers including this one presenting results on turbulent flux measurements at the ocean surface on the behavior of the marine atmospheric boundary layer on the ocean waves characteristics on the ocean circulation and on remote sensing of surface parameters this overview presents the background and objectives of fetch the experimental setup and operations and the dominant atmospheric and oceanic conditions and introduces the different papers of the special section

variation of the drag coefficient and its dependence on sea state using a gill propeller vane anemometer and resistance wave wires over a water column depth of 15 m simultaneous measurements of the momentum flux and sea surface wave spectra were acquired from the pisa mast 28 km offshore in the german bight during autumn and winter 1979 these data were analyzed to identify the relationship between wind stress and surface waves it was found that wind stresses for wind speeds above 15 m s were regularly higher than open ocean wind stresses as reported by smith 1980 and by large and pond 1981 for the same mean wind speed these results when described in terms of the drag coefficient compared closely with the results of sheppard et al 1972 who collected surface layer statistics over lough neagh northern ireland after modeling the surface waves of the north sea as a function of wave saturation or wave age it became evident that variations in the magnitude of the drag coefficient could be explained by coincident variations in the surface wave energy spectrum by applying the wave dependent roughness length model described by kitaigorodskii 1973 the north sea drag coefficient was predicted to be larger than drag coefficients reported from the open sea

the near neutral marine atmospheric boundary layer with no surface shearing stress a case study abstract data from a marine coastal experiment over the baltic sea comprising airborne measurements and mast measurements have been used to highlight the turbulence dynamics of a case with most unusual flow characteristics the boundary layer had a depth of about 1200 m the thermal stratification was near neutral with small positive heat flux below 300 m and equally small negative heat flux above the entire situation lasted about 6 hours turbulence levels were unexpectedly high in view of the fact that momentum flux was negligible in fact positive in the layers near the surface and buoyancy flux was also small the turbulence was found to scale with the height of the boundary layer giving rise to velocity spectra having the shape of those characteristic of convectively mixed boundary layers analysis of the turbulence budget for the entire planetary boundary layer pbl revealed that energy was produced from shear instability in the uppermost parts of the pbl and was distributed to the lower par