forces driving late pleistocene ca 77 12 ka landscape evolution in the cimarron river valley southwestern kansas abstract this study presents stratigraphic geomorphic and paleoenvironmental 13 c data that provide insight into the late pleistocene landscape evolution of the cimarron river valley in the high plains of southwestern kansas two distinct valley fills t 1 and t 2 were investigated three soils occur in the t 2 fill and five in the t 1 fill all indicating periods of landscape stability or slow sedimentation of particular interest are two cumulic soils dating to ca 48 28 and 13 12 5 ka 13 c values are consistent with regional paleoenvironmental proxy data that indicate the prevalence of warm dry conditions at these times the cimarron river is interpreted to have responded to these climatic changes and to local base level control specifically aggradation occurred during cool wet periods and slow sedimentation with cumulic soil formation occurred under warmer drier climates significant valley incision 25 m by ca 28 ka likely resulted from a lowering of local base level caused by deep seated dissolution of permian evaporite deposits

the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

middle holocene aeolian activity on the high plains of west central kansas the uppermost surficial stratigraphic unit south of the arkansas river in the kansas high plains is a previously unidentified middle holocene or younger loess the unit fits both a loess thickness and a particle size model for loess distribution with increasing distance from source a soil immediately below this unit is radiocarbon dated 6000 to 6700 years bp the radiocarbon ages indicate that the loess unit is younger than the commonly reported ranges for bignell loess in the great plains and demonstrate a need for re examining holocene loess stratigraphy of the great plains in some locations closest to the arkansas valley source this middle holocene unit is overlain by or interfingers with dune sands the presence of these aeolian sands indicates that following a period of relative landscape stability and soil development a shift toward a middle holocene climate in which aeolian processes dominated occurred about 6000 years ago on the high plains of west central kansas

chronological discord between the last interglacial paleosol s1 and its parent material in the chinese loess plateau abstract an and porter geology 25 1997 603 reported six high dust influx events of millennial timescales recovered from the last interglacial paleosol s1 and correlated them to six cool events of millennial timescale in the north atlantic however the complexity of soil forming processes may have made the chronological correlation with the north atlantic records inadequate to examine the complexity of the s1 formation the s1 paleosol was traced laterally and identified based on the preserved characteristics observed in the field and analyzed in the laboratory our data show that from the northwest to the southeast the s1 paleosol gradually converges from three distinctive soil profiles into a single welded profile because the net rate of loess accumulation was attenuated to the southeast and pedogenic development intensified southeastward during the last interglacial three soil forming events within the s1 paleosol s1s1 s1s2 and s1s3 separated by two loess units s1l1 and s1l2 in the northwestern part of the loess plateau are stratigraphically coeval with a single soil profile in the southeastern margin of the loess plateau in the southeast the s1 paleosol developed into underlying older loess l2 e g at the lantian section the three paleosols s1s1 s1s2 and s1s3 are partially welded in the central part of the chinese loess plateau e g at the tianshui section where the lower portion of s1 paleosol developed in the underlying older loess unit l2 in the northwestern margin of the chinese loess plateau e g at the lanzhou section the preservation of the repeating soil loess sequence s1s1 s1l1 s1s2 s1l2 and s1s3 continuously documented the climatic events of the last interglacial our data also show that the magnetic signatures and particle size information are more or less acceptable climatic proxies only for the northwestern sections where the degree of pedogenesis was lower and the rate of eolian influx was greater during the last interglacial it appears that in all cases investigated the median grain size and the coarse fraction 63 m content define the upper and lower boundaries of the s1 paleosol reasonably well and can be used to estimate the time transgressive nature of the s1 paleosol relative to its parent material soil welding bioturbation and material translocation within the s1 soil profiles make it impossible to preserve the detailed and high resolution information of climate changes in those s1 profiles in the southeastern part including the popularly called central part of the chinese loess plateau

paleosols and the effects of alteration abstract alteration of paleosols following development and burial is common chemical physical and mechanical processes can weld younger to older soil profiles and affect the accumulation dissolution and reprecipitation of mineral material in soils soil properties most affected include texture and porosity and the content and distribution of soluble salts amorphous silica gypsum carbonate and clay organic matter retention is highly dependent on post burial biologically controlled oxidation reduction and ph conditions processes such as erosion and deposition can truncate profiles or bury them either rapidly or extremely slowly effects of these and other processes on soil properties must be examined with care in paleosols that have been buried even for a short interval this study presents several examples of soil properties which should be evaluated carefully and possibly avoided as indicators in paleoenvironmental reconstruction paleosol classification and regional stratigraphic correlation

aeolian influx and related environmental conditions on gran canaria during the early pleistocene the island of gran canaria is regularly affected by dust falls due to its proximity to the saharan desert climatic oscillations may affect the saharan dust input to the island geochemical mineralogical and textural analysis was performed on a well developed and representative early pleistocene paleosol to examine saharan dust contribution to gran canaria significant and variable saharan dust content was identified in addition to weathering products such as iron oxides and clay minerals variations in quartz and iron oxide concentrations in the paleosol likely reflect different saharan dust input in more less contrasted rhexistasic biostatic climatic conditions linking the quartz content in canarian soils the ingenio paleosol and two canarian loess like deposits to different ages from the quaternary we hypothesized that the dust input should be lower about 33 38 throughout the early to middle pleistocene than during the late quaternary the saharan dust input to the gran canaria profile in the pleistocene persisted in spite of climatic variations

systematic variations in the carbon and oxygen isotopic composition of pedogenic carbonate along elevation transects in the southern great basin united states stable carbon and oxygen isotope variations in holocene soil carbonates that formed in the unsaturated zone were examined along several elevation transects in the southern great basin united states a region with a semi arid climate our intent was to study the relationship between the stable isotopic composition of pedogenic carbonates and climate ecological variations differences in parent material and soil depth 13 c of pedogenic carbonate in three different soil profiles from different elevations decreases with soil depth indicating a decrease in the ratio of atmospheric to plantderived co 2 downprofile pedogenic carbonate at the soil air interface approaches a 13 c value in equilibrium with atmospheric co 2 in all three soils observed 13 c profiles for pedogenic carbonate can be described using a one dimensional model for 12 co 2 and 13 co 2 assuming isotopic equilibrium between soil co 2 and soil carbonate the modeled best fit to observed isotopic profiles suggests that the profile differences in part result from differing soil respiration rates at each site 13 c in deep pedogenic carbonate 50 cm varies by about 12 per mil over a 2 440 m elevation range being enriched in 13 c at the lowest elevations the slope of 13 c for these carbonates versus elevation is very similar for soils developed on carbonate and on noncarbonate parent materials depletion by 4 6 to 4 7 per mil per 1 000 m increase in altitude between 300 to 2 740 m above mean sea level for the localities studied this concordance makes it likely that there has been complete isotopic exchange between hco 3 in solution and soil co 2 prior to carbonate precipitation soil co 2 and soil respiration rates increase systematically with elevation the plantderived component of soil co 2 indicates that c 3 plants dominate the biomass at most measured sites in agreement with plant surveys calculated equilibrium fractionation factors between soil co 2 and soil carbonate are very similar to those observed again indicating complete isotopic exchange between carbon species in all the soil co 2 and soil carbonate data suggest that the 13 c variation with elevation observed in the soil carbonates results from differing soil respiration rates at each site as well as from variations in the proportion of c 3 to c 4 and cam plants in each site9s surface biomass 18 o values in pedogenic carbonates are higher at lower elevations due in part to the more positive 18 o values for meteoric waters at lower elevations the average 18 o value of deep 50 cm pedogenic carbonate at all sites however is enriched 2 4 to 3 7 per mil with respect to values we predict should be in equilibrium with the isotopic composition of local meteoric waters this suggests that evaporative isotopic enrichment of soil waters may have occurred at all elevations prior to precipitation of carbonate or that seasonal differences in the isotopic composition of meteoric waters coupled with differential infiltration may be taking place one or both of these processes also may explain the 18 o decrease in soil carbonate with depth observed in two of three soil profiles

pedogenic modification of loess significance for palaeoclimatic reconstructions abstract this review considers the role of pedogenic processes in modifying wind blown dust loess concentrating particularly on the ways that resulting properties may be interpreted as indicators of past climatic conditions and changes emphasis is placed on the sequences of palaeosols developed within loess deposits that are frequently regarded as some of the best terrestrial equivalents of marine sediment records of long term global climatic change a palaeosol is generally interpreted in terms of the broad pedogenic processes and environments assumed to be currently responsible for that type of soil forming at the present surface even the very presence of a palaeosol may have palaeoclimatic significance however in that it is often taken to indicate a period of relative land surface stability and warmer and or moister conditions between cold and or arid phases of loess accumulation in reality it may be more useful to consider many loess palaeosol sequences in terms of changing balances between pedogenesis and loess accumulation over geological time in most regions it seems that the balance swings towards pedogenesis during interglacials or interstadials when sediment supply and transport are limited and the climate is warmer and or wetter where accumulation rates are still appreciable during these soil forming intervals however the soils and palaeosols may be accretionary with surface build up keeping pace with pedogenesis welding may also occur where covering sediments are insufficiently thick to isolate an underlying palaeosol from the effects of pedogenesis active at a new land surface further complications occur due to reworking of palaeosols and syndepositional pedogenic alteration of loess units generally such pedocomplexes can only be deciphered if the different pedogenic geomorphic and sedimentary processes are identified and ordered within a pedosedimentary reconstruction a recent trend has been to treat some loess palaeosol sequences as quasi continuous time series particularly when comparing depth functions of climatic proxy properties such as magnetic susceptibility and grain size with marine and ice core isotope curves

a study of the dynamics of the equatorial lower stratosphere by use of ultra long duration balloons 2 gravity waves in the late southern winter of 1998 centre national d etudes spatiales cnes the french space agency released six 10 m diameter superpressure balloons from a location near quito ecuador three balloons collapsed soon after launching but the remaining three drifted westward for a few weeks at altitudes between 19 and 20 km two of those balloons crossed the pacific ocean before falling above the maritime continent while the other completed a revolution around the earth and crossed the pacific for a second time before its final fall despite the small number and the relatively short duration of the flights the balloons provided a unique in situ data set for the lower equatorial stratosphere this part 1 of a two part paper describes this data set and analyzes outstanding features in the planetary scales part 2 focuses on gravity wave scale it is argued that balloon trajectories over the pacific are primarily determined by the westward drift during the easterly phase of the equatorial quasi biennial oscillation qbo and the meridional velocity field of a mixed rossby gravity yanai wave with an apparent period of 4 days and zonal wave number 4 this wave appears to have two episodes of amplification during the balloon flights it is also argued that the balloons show evidence of oscillations with periods between 2 and 4 days and of a kelvin wave with an apparent period close to 10 days and zonal wave number 1 in this way the balloon behavior provided a pictorial view of air parcel trajectory in the equatorial lower stratosphere it is stated that larger balloon campaigns can provide excellent in situ data sets for studies on the dynamics and composition of the middle atmosphere

stratigraphy sedimentology and environmental significance of late mid holocene dunes lauder sand hills glacial lake hind basin southwestern manitoba mid holocene eolian dune and sand sheet deposits rare in the northern great plains are buried under a meter or more of younger sediment in the glacial lake hind basin southwestern manitoba six facies observed in three cut bank exposures allow reconstruction of sedimentary processes and resulting landscape at the study site in the basin center around 6100 cal calibrated bp a mosaic of parabolic dunes with interdune and dune marginal lightly vegetated sand sheets developed in the souris river flood plain that was least partly covered with woodlands and wetlands during floods nearby interdune areas were inundated dune foreset orientation and stratification indicate a more easterly sand transport direction lending support to the hypothesis that more pervasive westerly zonal flow contributed to mid holocene aridity evident elsewhere in the northern great plains more arid conditions during the mid holocene may have helped trigger eolian activity however with the exception of a more active eolian

coexistence of deep and shallow water foraminiferal faunas off panama city florida benthic box core sampling along a transect off panama city florida in the vicinity of the desoto canyon from 37 m to 200 m depths were run throughout the bureau of land management s outer continental shelf environmental assessment program for the mississippi alabama florida mafla area from 1974 through 1978 seasonal samples were taken and analyzed for benthic distribution abundance diversity and faunal affinities the most striking feature brought out by foraminiferal analyses was the mixture of foraminifera from different depth zones species normally found in abundance only at depths of 100 m in adjacent areas were living at all shallower depths including 37 m coexisting with the deeper assemblage were all of the species normally encountered at the shallow depths species diversity normally showing a progressional increase from inner to outer shelf either remained constant or decreased due to the decrease of shallow water species with depth along with this mixed assemblage there was a planktonic foraminiferal content in the shallowest assemblage of as much as 25 normally planktonic percentage of similar water depths is 0 seasonality had minor effects on the assemblages the planktonic content is attributed to loop current water providing open gulf water to the inner shelf because the loop current is intermittent the consistently high percentages of deeper water species on the inner shelf must be attributed to up welling currents providing cooler deeper water to the inner shelf however since this deeper water did not restrict survival of shallow water species multiple factors must be considered for controlling benthic foraminiferal distribution

soil forming intervals caused by eolian sediment pulses in the lahontan basin northwestern nevada we have studied a series of toyeh post isotope stage 2 eolian dust fall was the source of fines and salts in these soils apparently this influx was concentrated during two brief intervals or pulses one during the holocene and one during the previous isotope stage 5 interpluvial leaching during the sehoo pluvial removed salts from churchill soils carbonate and soluble salts now observed in the churchill soils represent a toyeh overprint on the churchill profile these pulses of fine sediment and accompanying salts are tantamount to the soil forming intervals that morrison described in the lahontan area episodic eolian dustfall provides fine particles of silicates calcite and soluble salts that infiltrate into the clast supported alluvial piedmont sediments several hundred playas exist in the basin and range each providing directional dust contributions that influence local and regional soil development we counsel caution in assuming constant gradual development of soil properties without due consideration of paleoenvironmental influences on soil forming factors

a study of the low frequency inertio gravity waves observed during the pyrenees experiment the purpose of this paper is to analyze and interpret the onset of some well characterized transient inertio gravity waves observed during the pyrex pyrenees experiment campaign the data used are the high resolution soundings launched every 6 hours on both sides of the ridge in agreement with other observations made during the field campaign certain among those soundings often show steady mountain waves it appears that those waves are often transients and are followed by well characterized inertio gravity waves propagating upward and downward from the level where the initial mountain waves are large to interpret those observations it is suggested that the observed inertio gravity waves result from the geostrophic adjustment of the large scale flow that follows the transit and eventually the breaking of the main mountain wave this hypothesis is supported by an analytical calculation of inertio gravity waves emission from a momentum deposit that lasts a finite time the spatial extent of this forcing are also finite and its maximum amplitude is a fraction of the measured mountain drag

spatial and temporal patterns of late quaternary eolian deposition eastern colorado u s a abstract eolian sediment covers about 60 of colorado east of the rocky mountains about 30 of the sediment is sand and 70 is loess initially flood plains were the principal sources of eolian sediment but during the holocene dunes formed from older eolian sand and alluvium on uplands since latest pleistocene time dominant dune forming winds have been northwesterly in the northern part of the region and southwesterly in the southern part at present sand sheets and dunes mainly parabolic types are stable and covered with vegetation in dunes sand is commonly 20 30 m thick but elsewhere averages

large scale stabilized dunes on the high plains of colorado understanding the landscape response to holocene climates with the aid of images from space principal component analysis of landsat thematic mapper images from eastern colorado reveals stabilized dune fields that are composed of single and compound parabolic dunes some longer than 10 km these dunes have been reactivated at least four times in the past 10 000 yr at ca 9500 to 5500 yr b p 5500 to gt 4800 yr b p 4800 to gt 1000 yr b p and lt 1000 yr b p during droughts that probably exceeded the dry conditions during the 1930s dune orientations indicate that these landforms were molded by winds from the northwest which now dominate during the winter and spring with the passage of pacific air masses this study underscores the sensitivity of the landscape of the high plains to drought conditions which may become more prevalent because of the anticipated effects of greenhouse warming

paleosol classification problems and solutions abstract paleosols are soils that formed on landscapes of the geologic past three kinds exist buried exhumed and relict to help reconstruct paleoenvironments and for ease of comparison we suggest a property based classification system linked to genetic processes we use enduring properties because alteration of paleosols following burial is common morphological properties such as horizonation soil fabric root and worm casts and redoximorphic features are resistant to alteration and thus are valuable as criteria field observable and micromorphological properties degree of weathering and proportion of resistant minerals are also useful as criteria for paleosol orders total chemical analysis provides a proxy measure for base saturation and clay mineralogy we use proxy criteria to help classify paleosols that have changed markedly or have been lithified during or after burial to an earlier version of the system we add two new orders and include buried relict lithified and exhumed units at the suborder level our system clearly separates paleosol taxon names from those of all ground soils we use the prescript paleo at the order level and kryptic to designate the buried enduric to designate the relict lithic to designate the lithified and emergent to designate the exhumed paleosol suborders we use prescript modifiers to describe the physical characteristics of the paleosols and postscripts for parent material origin and the extensiveness of the paleosol landscape we present data and classify a number of paleosols as examples of the system

global estimates of equatorial inertia gravity wave activity in the stratosphere inferred from era40 reanalysis 1 a new methodology is applied to era40 reanalysis in order to quantify large scale inertia gravity wave activity in the equatorial lower stratosphere both eastward and westward propagating waves are identified in the data set and a good agreement is found with previously published in situ observations global estimates of vertical fluxes of zonal momentum associated with such waves are obtained typical amplitudes of order 10 2 m2 s 2 suggest that the forcing of the quasi biennial oscillation by large scale inertia gravity waves is tantamount to that by kelvin waves this method can be used to document the space time variability of the wave activity in order to improve the wave drag parameterizations in climate models

isotopic and geomorphic evidence for holocene climate southwestern kansas abstract the cimarron bend of southwestern kansas is characterized by loess dunes and sand sheets that reflect a complex eolian alluvial history stratigraphic evidence indicates that at least two major dune and sand sheet reactivation episodes occurred these follow intervals of alluviation stability and soil development in the holocene radiocarbon ages from paleosol horizons bracket these periods and their 13 c values provide evidence of a shift from a cooler wetter climate in the late pleistocene and early holocene dominated by c 3 plants to a warmer drier middle holocene period characterized by an increase in c 4 plants stable isotopic results for late holocene soils may reflect local rather than regional climatic conditions our results compare favorably with studies in the central and southern great plains together these results imply that a regional change toward a warmer drier climate occurred from the early to the middle holocene on the southern great plains

gravity waves in the tropical lower stratosphere an observational study of seasonal and interannual variability radiosonde observations made at cocos islands 12 s 97 e in the indian ocean between september 1992 and june 1998 are used to study seasonal and interannual variations in gravity wave activity in the lower stratosphere 18 25 km the islands are located in a region of generally strong convection that occurs at all times of the year with the period of strongest convective activity between december and july wet season the prevailing zonal winds during the observational period and height range are westward with a quasi biennial oscillation qbo superimposed time series of wave energy show that largest wave amplitudes occur during the wet season when convection is strongest but a qbo like variation is also apparent maximum energy densities of about 25 j kg 1 occur early 1993 1995 and 1997 at the times when the westward shears are largest wave energy is found to be propagating upward and in the horizontal there is considerable azimuthal anisotropy with predominate eastward propagation against the prevailing wind upward fluxes of zonal momentum flux u w are estimated by combining the temperature and wind information fluxes show a similar temporal behavior to the energy the motion and temperature fields are dominated by waves with vertical wavelengths 2 km using a stokes parameter analysis it is found that the intrinsic frequencies are on average 2 3 times the inertial frequency corresponding to intrinsic periods of 20 25 hours horizontal wavelengths between 200 and 2000 km are inferred with a mean value of about 1000 km the mean intrinsic phase speeds are about 10 ms 1 but ground based phase speeds are centered on 0 ms 1

studies on settling traction and entrainment of larger benthic foraminiferal tests implications for accumulation in shallow marine sediments settling and traction velocities were measured on optimally preserved tests of larger foraminifera using a settling tube and flume tank within larger foraminifera with porcelaneous tests the peneroplids peneroplis antillarum p planatus p pertusus and dendritina cf d zhengae are distinguished by low test densities ca 1 2 that do not change with growth buoyancy is high because of low reynolds numbers and increases in large individuals because of the allometric change of test shape the fusiform alveolinella quoyi with test densities ca 1 6 is characterized by high reynolds numbers inducing the weakest buoyancy within porcelaneous larger foraminifera the highest buoyancy was recorded for the three soritids parasorites orbitolitoides sorites orbiculus and amphisorus hemprichii because of their low test densities ca 1 25 and the extremely flat biconcave plate like shape flat tests however reduce traction and entrainment from smooth surfaces within hyaline larger foraminiferat the amphisteginids show thick lenticular amphistegina lobifera a radiata to thin lenticular tests a bicirculata a papillosa influencing buoyancy here high test densities ca 1 8 decrease with growth in a lobifera a lessonii and a bicirculata and remain constant in a radiata and a papillosa minimum velocities required for entrainment are lower for thick lenticular tests and higher for thin lenticular tests test densities remain constant with growth in the calcarinid baculogypsina sphaerulata 1 78 and decrease slightly in calcarina gaudichaudii and neorotalia calcar starting at 1 85 all living under extreme hydrodynamic conditions density decreases the most in baculogypsinoides spinosus starting at 1 8 resulting in higher buoyancy through low reynolds numbers traction is promoted in spherical tests of baculogypsina and baculogypsinoides within nummulitids the thick lenticular palaeonummulites venosus test density decreasing with size starting at 1 78 is less buoyant expressed in high reynolds numbers but easily entrained thick lenticular juveniles and extremely flat adults distinguish operculinella cumingii heterostegina depressa and the giant cycloclypeus carpenteri test densities increase during growth starting from ca 1 6 and attaining a maximum of 1 8 buoyancy is low in small tests and high in large tests while entrainment velocities are reduced as the tests flatten high buoyancy is also a characteristic of the entirely flat tests in operculina ammonoides from deeper regions and planostegina operculinoides which is expressed in the lowest reynolds numbers within larger foraminifera

modern and late holocene wind regimes over the great plains central u s a the great plains of the central united states contain numerous presently stabilized dune fields that were active during the late holocene the most recent period of reactivation occurred about 700 1000 years ago during the medieval climatic anomaly a period of frequent severe drought recognized throughout the north american west dune orientations and internal bedding preserve information about paleowinds from this time period we compared paleowind information with modern winds and potential sand transport analyzed from meteorological data while both reconstructed paleowinds and modern winds include a strong northwesterly component over the northern to central portions of the great plains a significant difference exists to the south during the late holocene southwesterly winds had a strong influence on dune forms over the central and southern great plains while modern potential sand transport is dominated by southerly to southeasterly winds that bring moisture to the region from the gulf of mexico hypothetical dune types forming under modern winds would be different and have different crestal orientations than those preserved from the late holocene in order for such a shift in southerly winds to take place it is likely that 1 the typical position of the bermuda high in summer was shifted either to the east or to the south resulting in weaker low level winds from the south and southeast and greater extent of southwesterly winds on the great plains and or 2 drought likely enhanced by evapotranspiration and soil moisture feedbacks brought the normally higher level southwesterly flow down to the land surface given our understanding of megadroughts over the great plains as well as recent climate predictions for increased warmth and drought over this area future reactivation of the dunes seems likely

stratospheric variability of wave activity and parameters in equatorial coastal and tropical sites during the west african monsoon recent numerical studies in stratospheric dynamics and its variability as well as climate have highlighted the need of more observational analyses to improve simulation of the west african monsoon wam in this paper activity and spectral characteristics of short scale vertical waves wavelengths 4 km are analysed in equatorial coastal and tropical lower stratosphere during the wam a first detailed description of such waves over west africa is derived from high resolution vertical profiles of temperature and horizontal wind obtained during intensive observation period of the african monsoon multidisciplinary analyses amma campaign 2006 monthly variation of wave energy density is revealed to trace the progression of the inter tropical convergence zone itcz over west africa mesoscale inertia gravity waves structures with vertical and horizontal wavelengths of 1 5 2 5 and 400 1100 km respectively and intrinsic frequencies of 1 1 2 2 f or periods 2 days are observed in the tropical ls with intense activity during july and august when the wam is installed over the tropical west africa over equatorial region gravity waves with intrinsic frequencies of 1 4 4 f or periods 5 2 days vertical wavelength of 2 1 km and long horizontal wavelengths of 1300 km are intense during the wam coastal phase from july to october gravity waves with intrinsic frequencies of 1 2 3 8 f or periods 6 days vertical wavelength of 2 1 km and horizontal wavelengths of 1650 km are less intense during the wam sahelian phase of the wam march june unlike potential energy density kinetic energy density is observed to be a good proxy for the activity of short scale vertical waves during the wam because quasi inertial waves are dominant long term wave activity variation from january 2001 to december 2009 highlights strong year to year variation superimposed on convective activity and quasi biennial oscillation like variations especially above tropical stations

tropospheric stratospheric wave propagation during el nino southern oscillation 1 traditional and 3 d extended eliassen palm ep fluxes for the globe between the 3 and 600 hpa levels are used to calculate el nino southern oscillation enso composites few of the warm minus cold departures of the traditional ep fluxes are significant at the 95 confidence level in contrast the enso composite differences of the longitudinally dependent extended ep flux have broad regions of significance for a wide range of latitudes longitudes and heights during an enso event there are significant vertical fluxes of wave energy across the tropopause over the subtropical pacific in addition there is substantial meridional exchange of wave energy in the upper troposphere and lower stratosphere in this region proceeding northward the changes in the stratosphere are associated with meridional exchanges of wave energy and strong vertical fluxes of wave energy across the pacific and north america the higher latitude changes have a westward tilt with height and eastward group velocities both suggesting the importance of rossby waves in the atlantic region there are strong downward fluxes of wave energy which may be part of an important enso pathway into europe overall these results strongly suggest the importance of nonzonally averaged dynamics in the stratospheric responses to enso

interpretations and common challenges of aeolian records from north american dune fields abstract geomorphic and chronologic data for dune fields are evaluated for three contrasting areas of north america 1 the prairie parkland and boreal ecozones of the northern great plains in canada 2 the central great plains of the usa and 3 the deserts of southwestern usa and northern mexico luminescence and radiocarbon ages for periods of dune accumulation and stability are compared with palaeoenvironment proxies to provide an assessment of the boundary conditions of dune system response to changes in sediment supply availability and mobility dune fields in the northern great plains were formed from sediment originating from glaciofluvial or glaciolacustrine sediments deposited during deglaciation 16 11 ka subsequent aeolian deposition occurred in parkland and prairie dune fields as a result of mid holocene 8 5 ka and late holocene despite spatial and temporal gaps in chronometric data as a result of sampling biases the record from north american dune fields indicates the strong influence of sediment supply on dune construction with changes in sediment availability as a result of drought episodes resulting in dune field reactivation and reworking of pre existing sediment

particle size fractionation of eolian sand along the sinai negev erg of egypt and israel eolian sand fractions along the west east transport system of the northern sinai peninsula northwestern negev erg of egypt and israel were analyzed in this study with regard to source dune geomorphology eolian transport and paleoclimate the studied erg is composed of active linear seif dunes in northern sinai western part and stabilized vegetated linear dunes in the nw negev dune field eastern part linear seif dunes differ from vegetated linear dunes in their vegetation cover linearity internal structure and dynamics sand samples were analyzed for sand grain morphology and particle size distribution although both dune types are continuous landforms with similar orientations and sand grain roundness values the linear dunes of sinai are coarser grained than the negev vegetated linear dunes the vegetated linear dunes have a variable but higher proportion of very fine sand 50 125 m content and a varying but lower sand fining ratio defined as the ratio of fine sand percentage to very fine sand percentage from these observations we infer that fractionation of sand occurred along the studied eolian transport path during periods of enhanced windiness very fine sands are suggested to have been transported by saltation and low suspension from source deposits and sand sheets we suggest that a significant proportion of the very fine sand fraction of nile delta sands has been transported downwind through northern sinai during the late pleistocene especially when linear dunes reached the nw negev due to last glacial period windiness and probably larger sediment supply generally decreasing wind velocities and increasing precipitation along the west east dune transport path enhanced vegetative cover in the northern negev and enabled deposition of the very fine sand component within the dunes and probably further downwind our results suggest that particle size distribution can elucidate much about erg history over time scales of a glacial interglacial cycle especially in cases where the sand provenance is of a single dominant source

recent foraminifera tracers of oceanic water movements in the southwestern lagoon of new caledonia abstract water movements in the southwestern lagoon of new caledonia are controlled mainly by tidal currents and by a wind driven surface current to the northwest balanced by a subsurface return current to the southeast during each rising tide oceanic water inflows over the barrier reef through the passes and between the scattered reefs of the southeast the distribution of planktonic foraminiferal tests shows that most of the superficial oceanic water is pushed by the southeast trade winds to the inner part of the bay de boulari the distribution of some benthic species especially gypsina globula reuss and pyrgo denticulata brady is also related to an oceanic inflow the distribution of their tests follows the trajectory of subsuperficial oceanic water penetrating into the lagoon through the passes and gives a clear picture of these water movements this image based on thanatocoenoses can be preserved after diagenesis therefore its possible utilization in similar paleoenvironments can be considered

model study of intermediate scale tropical inertia gravity waves and comparison to twp ice campaign observations abstracta 2 day inertia gravity wave igw was observed in high resolution radiosonde soundings of horizontal wind and temperature taken during the 2006 tropical warm pool international cloud experiment twp ice experiment in the darwin area the wave was observed in the stratosphere above darwin from 28 january to 5 february a similar wave event is observed in the european centre for medium range weather forecasts ecmwf operational data a comparison between the characteristics of the igw derived with the ecmwf data to the properties of the wave derived with the radiosonde data shows that the ecmwf data capture similar structure for this 2 day wave event but with a larger vertical wavelength a reverse ray tracing method is used to localize the source region using ecmwf data to define the atmospheric background conditions and wave properties observed in the soundings it is found that the 2 day wave event originated from deep convection in the indonesian region around 20 january the weather research

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

geographic variations in particle size distribution of the last interglacial pedocomplex s1 across the chinese loess plateau their chronological and pedogenic implications abstract due to northwestward attenuation of the summer monsoon and northwestward intensification of loess deposition during the last interglacial the last interglacial pedocomplex s1 gradually differentiated from the northwest to the southeast the three paleosols s1s1 s1s2 s1s3 corresponding to the marine isotope sub stages 5a 5c and 5e and the two intercalated loess units s1l1 s1l2 corresponding to the marine isotope sub stages 5b and 5d are completely preserved at northwestern sections towards southeast both the s1l1 and s1l2 were annexed by the subsequent paleosol development s1s1 and s1s2 and the three paleosols s1s1 s1s2 and s1s3 were partially welded at the southeasternmost site the three soil forming events s1s1 s1s2 and s1s3 repeatedly occurred in a single paleosol profile the three observed orders of particle size variations are interpreted to have imprinted important chronological and pedogenic signatures first order variations i e a remarkable difference between the interglacial pedocomplex s1 and the glacial loess units l1 and l2 implies that the s1 parent material was considerably finer in the source areas or and the proximity to the source areas was much farther during interglacial period than during the preceding l2 and following l1 glacial periods second order variation i e the parenthetical trends in 63 m and

reef shallowing is a critical control on benthic foraminiferal assemblage composition on nearshore turbid coral reefs abstract declining water quality represents a major threat to the coral reefs of australia s great barrier reef gbr due to their close proximity to river point sources reefs situated on the inner shelf of the gbr are widely perceived to be most susceptible to the increased discharge of nutrients and sediments from coastal catchments many of which have been modified since european settlement however the impact and magnitude of water quality change on the gbr s inner shelf reefs remains unclear much of the uncertainty can be attributed to a paucity of long term records with which to assess ecological and environmental change over appropriate reef building timescales here we present benthic foraminiferal palaeo records from three proximal nearshore turbid zone reefs located within the central region of the gbr bayesian age depth modelling was used to identify the core intervals corresponding to the timing of european settlement in the region c 1850 ce enabling the investigation of 1 the composition and variability of benthic foraminiferal assemblages during reef shallowing towards sea level and 2 whether any signal of increased nutrient and sediment inputs as the result of historical land use change can be discerned on the most nearshore reefs of the central gbr multivariate analyses identified two assemblage groups delineated by a significant increase in the relative abundance of pararotalia spp up core our results suggest that post european settlement associated increases in nutrient and sediment inputs are unlikely to have driven the observed shifts in benthic foraminiferal assemblage composition rather we interpret changes in the composition of benthic foraminiferal assemblages as being linked to changes in hydrodynamic energy light availability and the carbonate content of reef matrix sediments during reef shallowing towards sea level our findings support the hypothesis that nearshore turbid zone reefs have a higher resistance to increased nutrient and sediment inputs than those located further offshore towards the inner mid shelf boundary of the gbr

middle holocene drought on the southern high plains abstract the climate of the southern high plains during the middle holocene is indicated by data from a variety of sources stratigraphic geomorphic and pedologic research at six localities in draws several dune sites and one playa lake basin show that widespread eolian erosion and sedimentation began in some areas by 9000 yr b p and culminated 6000 4500 yr b p probably because of warmer drier conditions that reduced the vegetative cover archaeological investigations at three sites provide evidence for the excavation of wells at this time apparently because of a declining water table studies of a few vertebrate and invertebrate faunas also indicate warming and drying in the middle holocene climate models and very limited isotopic data from bison bone suggest that summers in the middle holocene were warmer than present with reduced effective precipitation all lines of evidence indicate that the southern high plains was subjected to prolonged drought in the middle holocene with a maximum between 6500 and 4500 yr b p conforming climatically and chronologically to the altithermal

characteristics of kelvin waves and gravity waves observed with radiosondes over indonesia profiles of wind velocity and temperature at 0 35 km were observed by means of radiosondes in west java indonesia during november 1992 and april 1993 and used to study the behavior of various atmospheric waves in the equatorial atmosphere an oscillation of zonal winds with a period of about 27 days was found in the troposphere which was associated with variations in humidity and cloud top height kelvin waves showed phase progression beginning at cloud top height 13 16 km and were particularly enhanced near the tropopause the kelvin waves strongly modulated the tropopause structure including the tropopause height minimum temperature and atmospheric stability a hodograph analysis was applied to determine the propagation characteristics of inertial gravity waves height variation of the vertical group velocity suggests that the gravity waves were generated in the troposphere while the horizontal phase velocity distribution suggests that they were interacting with the background mean zonal winds these wave activities were enhanced when tall convective clouds passed over the site suggesting that cumulus convection seems to play a key role in generating these waves in the equatorial region

soil evolution along an altitudinal transect in the eastern mojave desert of nevada u s a amundson r g chadwick o a sowers j m and doner h e 1989 soil evolution along an altitudinal transect in the eastern mojave desert of nevada u s a geoderma 43 349 371 six soil profiles were examined along an altitudinal transect from 840 to 2170 m in the eastern mojave desert of southern nevada the soils formed on gravelly limestone alluvium which varied in age from holocene to mid pleistocene climate and vegetation varied from an arid desert scrub community at the low elevation to a sub humid coniferous forest at the highest elevation silicate clay mineralogy was similar to that of the parent material in all the holocene soils but differed with elevation in the mid pleistocene soils these being dominated by palygorskite at 1400 m and smectite at 2150 m pedogenic carbonate content of the bk horizons and morphologic stage of carbonate accumulation increased with soil age with the exception of the 2150 m site where excess moisture leaches carbonate out of the profile dcb extractable iron increased with both age and elevation whereas soil organic c and c02 increased primarily with elevation reflecting the gradient in moisture regime and biologic productivity aeolian dust may have a strong role in the formation of the vesicular platey surface horizons at many of the sites

inertia gravity waves observed by the uk mst radar we present an analysis of eight years data from the uk mst radar at aberystwyth wales to determine the occurrence and properties of long period quasi monochromatic oscillations in the wind vector identified with inertia gravity waves wave perturbations were first isolated by filtering out background wind variation in the vertical then the continuity of the radar measurements was exploited to apply band pass filters in time to select quasi monochromatic oscillations with periods 4 8 hours or 12 24 hours by searching for altitude regions where the wind vector rotates systematically with height and fitting ellipses to such sections the properties of inertia gravity waves can be derived to guard against contamination by short intrinsic period mountain waves cases were discarded when the vertical velocity measured by the radar exceeded 15 cm s 1 results show that waves in the stratosphere are dominated by upward energy propagation clockwise rotation and those in the troposphere by downward propagation consistent with the dominant source for inertia gravity waves being at tropopause level long period waves 12 hours are observed 70 of the time in the lower stratosphere roughly twice as often as the shorter period waves and 10 20 of the time in the troposphere there is a winter maximum in occurrence in the troposphere and for the short period stratospheric waves however the dominant long period waves show little seasonal dependence likewise they show only a weak correlation with jet stream velocity or direction unlike the other categories which are preferentially associated with strong jet streams and propagate along the jet inertia gravity waves observed by the radar have typical amplitudes 1 2 m s 1 and vertical wavelength 2 km the intrinsic wave period estimated for non jet stream conditions is similar for the two band passed series pointing to the importance of doppler shifting in generating the observed oscillations copyright 2007 royal meteorological society

climatic implications of the late quaternary alluvial record of a small drainage basin in the central great plains four late quaternary alluvial fills and terraces are recognized in wolf creek basin a small 163 km2 drainage in the kansas river system of the central great plains two terraces were created during the late pleistocene the t 4 is a fill top terrace underlain by sand and gravel fill fill i and the t 3 is a strath terrace cut on the cretaceous dakota sandstone both fill ii early holocene and fill iii late holocene are exposed beneath the t 2 a holocene fill top terrace the t 1 complex consisting of one cut and three fill top terraces is underlain by fills iii and iv a poorly developed floodplain t 0 has formed within the past 1000 yr as valleys in wolf creek basin filled during the early holocene an interval of soil formation occurred about 6800 yr b p early holocene fill has been found only in the basin s upper reaches indicating that extensive erosion during the middle holocene removed most early holocene fill from the middle and lower reaches of the basin valley filling between 5000 and 1000 yr b p was interrupted by soil formation about 1800 1500 and 1200 yr b p as much as 6 m of entrenchment has occurred in the past 1000 yr holocene events in wolf creek basin correlate well with those in other localities in the central great plains indicating that widespread changes in climate along with adjustments driven by complex response influenced fluvial activity

revisiting the quaternary development history of the western new caledonian shelf system from ramp to barrier reef abstract the present paper is based on the study of a new core tenia 3 151 20 m long and revisitation of previous core data from the western new caledonian barrier reef based on variations in lithology and stable isotope signatures and the occurrence of unconformity surfaces the tenia 3 sequence is subdivided into ten units regarded as deposited during interglacial high sea levels five detrital and two framework facies are delineated using their biological and textural attributes including coral growth forms and assemblages these facies are interpreted as representative of outer to inner carbonate shelf ramp to barrier reef environments variations in the facies within each stratigraphic unit occur mainly as vertical transitions from lower energy and probably deeper to higher energy probably shallower settings the succession of depositional events is reconstructed using all available age criteria including lithostratigraphy magnetostratigraphy uranium series dating and nannofossil biostratigraphy shallow water coral communities appear to have been developed as soon as carbonate deposition started at around 1 2 million years ma but the initiation of typical coral reef tracts is likely to have occurred not prior to 0 40 million years during marine isotope stage mis 11 carbonate deposition previous to mis 11 is considered to have operated along an open shelf margin i e a ramp or non rimmed platform based on the re examination of the core dataset previously acquired from the new caledonian reefs the coral communities dominated by massive forms mainly poritids are assumed to have remained stable in composition over the past 1 4 ma similarly as indicated by a preliminary study of pollen assemblages in the core the composition of terrestrial flora dominated by podocarpaceae and araucariaceae has not apparently suffered significant change over the past 1 ma and reflects climate conditions cooler and drier than today mean subsidence rates are derived tentatively over the past 1 ma from the stratigraphic position at present reached by the top of depositional units mean rates of 0 08 mm yr 1 for the western new caledonian margin are consistent with past sea level estimates the quaternary depositional history of the new caledonian shelf margin appears to have been controlled by both the amplitude of sea level changes and by differing vertical tectonic movements comparison between the depositional shelf histories from western new caledonia north eastern australia southern belize and the ryukyu islands supports the assumption that coral populations over the early and mid pleistocene developed as non reefal communities along ramp systems not forming continuous outer shelf reef rims at a global scale quaternary reef rimmed platforms are likely to have initiated after the mid pleistocene climate transition from marine isotope stage 11 at about 0 4 ma

gravity waves appearing in a high resolution gcm simulation global characteristics of gravity waves in the lower stratosphere are examined using a gcm with high resolution in both the horizontal t106 corresponding to about 120 km and the vertical 600 m the bottom boundary condition of the model is that of an aquaplanet with perpetual february sea surface temperature the simulated gravity waves are in good agreement with mesosphere stratosphere troposphere mst radar observations at a middle latitude on the gravity wave structure and on the frequency spectra as a function of height the frequency spectra of simulated wind and temperature fluctuations are also examined as a function of latitude large values of spectral density are observed at frequencies higher than the inertial frequency f in a weak wind region around 20 km which is consistent with the characteristics of internal gravity waves an isolated peak is observed near f for horizontal wind spectra at latitudes higher than 108 while the energy is distributed in a wide range of frequency at lower latitudes where f approaches zero further analysis is performed of those fluctuations having periods shorter than 24 h and those having vertical wavelengths smaller than 5 km these are frequently analyzed as gravity waves using observation data the distribution of energy and momentum fluxes in the latitude height section is examined the result indicates that short period waves mostly propagate upward and poleward from the equatorial region the wave energy reaches about 508 lat at the 27 km altitude a negative positive maximum of vertical flux of meridional momentum y9w9 is seen above the subtropical jet in the northern southern hemisphere for small vertical scale gravity waves this is consistent with the preferred equatorward propagation of the wave indicated by a statistical analysis based on mst radar observations the ratio of potential to kinetic energy maximizes over the equator and decreases poleward the eliassen palm flux divergence associated with gravity waves is decelerative above the subtropical jet albeit small

late quaternary environmental reconstructions of playa lunette system evolution on the central high plains of kansas united states playas are small ephemeral wetlands found throughout semiarid and arid regions around the world lunettes are dunes that form downwind of some large playas two playa lunette systems on the high plains were investigated to reconstruct paleoenvironments during playa lunette system evolution both playa lunette systems are composed of sediment spanning 40 k y with earliest deposits accumulating during at least marine isotope stage mis 3 and possibly starting as early as mis 5 the gilman canyon formation pedocomplex dating between 42 and 28 ka dominates this period and is ubiquitous throughout the playa lunette systems climate during mis 3 was similar to modern with warm temperatures low effective moisture and playa floors exposed long enough to allow pedogenesis during mis 2 climate was relatively cool with higher effective precipitation and playas were inundated for longer periods the regionally expressed brady soil of the pleistocene holocene transition caps these deposits and dates between 11 8 and 9 4 ka during the pleistocene holocene transition climate warmed yet moisture availability remained relatively high several distinct shifts in 13 c identify rapid climate changes associated with the bolling allerod younger dryas chronosequence warming continued into the holocene though moisture availability was highly variable holocene soils are common and date between 8 3 and 3 6 ka playa lunette system stratigraphy represents a continuum of the upland loess sequence though deposits are altered by playa hydrology geomorphic processes alternated between dissolution and fluvial eolian driven processes as climate changed and playas developed due to the aggradational environment and sensitivity of these systems high resolution records of environmental change throughout their evolution are preserved

correlation of loess paleosol sequences in east and central asia with se central europe towards a continental quaternary pedostratigraphy and paleoclimatic history abstract as recent small climatic fluctuations on a 102 103 year time scale can be correlated worldwide and represent a decline of mean annual temperature of only 1 c major climatic changes on at least a 105 year scale glacial interglacial cycles and probably a 104 year scale the approximate length of an interglacial must be of similar ages throughout the temperate climatic belt of the northern hemisphere this concept allows continental pedostratigraphical correlations detailed knowledge of the genesis of paleosols is needed to establish loess paleosol stratigraphies that can be used for paleoclimatic reconstruction most paleosols however are truncated and largely recalcified from overlying loess micromorphological studies allow primary and secondary carbonates to be distinguished and provide unequivocal evidence of clay illuviation this enables the recognition of typical loess weathered loess and the recognition of different genetic soil horizons such as cb bc ah bw and bt horizons for the brunhes epoch the sequence at karamaydan tadjikistan is more detailed than the corresponding section in luochuan china and even more than in se central europe except for the last glaciation the very good correlation with the deep sea oxygen isotope record which includes the development of an accurate astronomical time scale allows a detailed chronostratigraphical subdivision of the loess paleosol sequence in karamaydan which therefore should be regarded as a key sequence for reconstructing the climatic history of the brunhes epoch this implies that the loess paleosol sequences in se central europe are less complete than thought earlier pedocomplexes in karamaydan correspond with single paleosols in se central europe e g the f6 paleosol in stari slankamen correlates with pedocomplexes pk vi and v at karamaydan which were formed over a period of about 140 ka although pedogenesis was interrupted several times by loess deposition the f6 soil is therefore an example of a welded paleosol as are the f5 the f4 and the f2 paleosols in se central europe for most of the matuyama epoch the central and lower parts of the sequence at chashmanigar show more pronounced paleosols than the equivalent parts at luochuan in se central europe only at stari slankamen are three strongly developed though truncated paleosols f9 f11 above neogene sediments mineralogical investigations of the silt and clay subfractions show that there is little difference in the type and amount of pedogenic clay mineral formation between the holocene soils and the paleosols of the brunhes epoch at karamaydan and of the matuyama epoch at chashmanigar this suggests that the interglacial climates represented by the b or bt horizons of the buried paleosols of late middle and early pleistocene age were similar to that of the holocene

late quaternary eolian sand depositional record for southwestern kansas landscape sensitivity to droughts abstract eolian deposits and landforms are ubiquitous in western kansas particularly south of the arkansas river with the presence of a stabilized dune field stratigraphic studies and associated optical dating reveal a complex depositional history for this dune field spanning the late quaternary the oldest eolian deposits from ca 16 to 12 ka completely or partially bury high terraces with ages of ca 16 and 33 ka it is unknown whether these eolian deposits reflect regional aridity and or a change in sediment availability with the transition of the arkansas river from a single channel to a braided system there is pervasive evidence for episodic eolian erosion and deposition ca 9 8 to 6 3 ka generally coincident with loess deposition on upland surfaces olson c g nettleton w d porter d a brasher b r 1997 middle holocene aeolian activity on the high plains of west central kansas holocene 7 3 255 261 and thus it is inferred to reflect regional aridity sites within the dune field show a sequence of eolian sands and weak buried soils reflecting either dune migration or sand sheet accretion at ca 1490 430 380 320 180 and 70 yr ago which correspond well with continental scale droughts in the tree ring record eolian sand in the arkansas river dune field may be derived principally with variability in fluvial activity and in climate during the late pleistocene to the middle holocene with substantial reactivation of eolian systems during decadal scale drought variability in the past 2000 yr

equatorial atmospheric waves and their association to convection equatorial wave systems and their relationships with convective activity are analyzed in the western and central pacific regions during the coupled ocean atmosphere response experiment coare intensive observation periods the study uses geostationary meteorological satellite infrared temperature observations and the operational european centre for medium range weather forecasts analyses supplemented with coare observations spectral and complex principal component analysis are applied to the data using the linear theory of equatorially trapped waves as a guideline the existence of three types of waves is detected in the 7 10 day period range n 5 1 rossby waves are found to the east of the date line in a region of weak convective activity over the western equatorial pacific where intense convection occurs the 7 10 day waves do not possess the general characteristics of linear rossby waves but they are strongly linked to the active phases of westerly wind bursts and of convection analysis of the meridional wind reveals intense mixed rossby gravity waves with a mean 5 day period and westward phase and eastward group velocities over the western pacific the convection is found to be strongly correlated with the antisymmetric structure of the divergent field as predicted by the linear theory in the 200 hpa divergence field n 5 1 gravity waves are visible having periods shorter than 2 5 days they rapidly propagate about 25 m s21 both westward and eastward and have strong correlations with convective clusters

last glacial loess in the conterminous usa the conterminous united states contains an extensive and generally well studied record of last glacial loess the loess occurs in diverse physiographic provinces and under a wide range of climatic and ecological conditions both glacial and non glacial loess sources are present and many properties of the loess vary systematically with distance from loess sources united states midcontinent last glacial loess is probably the thickest in the world and our calculated mass accumulation rates mars are as high as 17 500 g m 2 yr at the bignell hill locality in nebraska and many near source localities have mars greater than 1500 g m 2 yr these mars are high relative to rates calculated in other loess provinces around the world recent models of last glacial dust sources fail to predict the extent and magnitude of dust flux from the mid continent of the united states a better understanding of linkages between climate ice sheet behaviour routing of glacial meltwater land surface processes beyond the ice margin and vegetation is needed to improve the predictive capabilities of models simulating dust flux from this region r 2003 elsevier ltd all rights reserved

correlation between fragipans and permafrost with special reference to silty weichselian deposits in belgium and northern france abstract a comparison is made between the properties of permafrost and those of fragipans the permafrost characteristics are summarized from published data on active permafrost and from personal observations on fossil permafrost the study of the fragipans mainly concerns the silty sediments of weichselian age which occur in belgium and northern france the distribution and the physical macromorphological and micromorphological properties of fragipans can all satisfactorely be explained by the growth of segregated ice during permafrost aggradation particularly striking is the relationship of both permafrost and fragipans to drainage conditions the quantity of segregated ice is highest in moist or poorly drained soil and it is at such places that the best developed fragipans are observed certain arguments that can be stated against the hypothesis of fragipan genesis by permafrost are discussed 1 the development of a platy structure by freeze thaw or by wet dry cycles 2 the discontinuous distribution of the fragipan 3 the development of the fragipan by pedogenetic weathering and migration processes it is concluded that only the permafrost hypothesis can explain the complete set of properties of the fragipan

neogene history of the west pacific warm pool kuroshio and leeuwin currents 1 foraminiferal analysis of miocene to recent strata of the northwest shelf of australia is used to chart west pacific warm pool wpwp influence the assemblage is typified by larger foraminifera with ingressions of the indo pacific smaller taxa asterorotalia and pseudorotalia at around 4 ma and from 1 6 to 0 8 ma a review of recent and fossil biogeography of these taxa suggests their stratigraphic distribution can be used to document wpwp evolution from 10 to 4 4 ma a lack of biogeographic connectivity between the pacific and indian ocean suggests indonesian throughflow itf restriction during this period the collision of australia and asia trapped warmer waters in the pacific creating a central wpwp biogeographic province from the equator to 26 n by 3 ma indo pacific species migrated to japan with the initiation of the modern kuroshio current coinciding with the intensification of the north pacific gyre and northern hemisphere ice sheet expansion indo pacific taxa migrated to the northwest australia from 4 4 to 4 ma possibly because of limited itf the absence of indo pacific taxa in northwest australia indicates possible itf restriction from 4 to 1 6 ma full northwest australian biogeographic connectivity with the wpwp from 1 6 to 0 8 ma suggests an unrestricted stronger itf compared to today and the initiation of the modern leeuwin current the extinction of some indo pacific species in northwest australia after 0 8 ma may be related to the effects of large glacial interglacial oscillations and uplift of the indonesian archipelago causing indonesian seaway restriction

benthic foraminiferal response to late glacial and holocene sea level rise and rainfall variability off east africa analogous to west and north africa east africa experienced more humid conditions between approximately 12 and 5 kyr bp relative to today while timing and extension of wet phases in the north and west are well constrained this is not the case for the east african humid period here we present a record of benthic foraminiferal assemblages and sediment elemental compositions of a sediment core from the east african continental slope in order to provide insight into the regional shallow indian ocean paleoceanography and east african climate history of the last 40 kyr during glacial times the dominance of a benthic foraminiferal assemblage characterized by bulimina aculeata suggests enhanced surface productivity and sustained flux of organic carbon to the sea floor during heinrich stadial 1 h1 the nuttallides rugosus assemblage indicates oligotrophic bottom water conditions and therefore implies a stronger flow of southern sourced aaiw to the study site during the east african humid period the saidovina karreriana assemblage in combination with sedimentary c n and fe ca ratios suggest higher river runoff to the indian ocean and hence more humid conditions in east africa between 8 5 and 8 1 kyr contemporaneous to the globally documented 8 2 kyr event a severe reduction in river deposits implies more arid conditions on the continent comparison of our marine data with terrestrial studies suggests that additional moisture from the atlantic ocean delivered by an eastward migration of the congo air boundary during that time period could have contributed to east african rainfall since approximately 9 kyr the gaining influence of the millettiana millettii assemblage indicates a redevelopment of the east african fringe reefs

holocene records of environmental change in high plains playa wetlands kansas us holocene environmental change is poorly characterized throughout much of the high plains playa wetlands are sites with appreciable potential for reconstructing environmental change because of their environmental sensitivity radiocarbon litho and magneto stratigraphic and stable carbon isotope 13c data for four playas on the kansas high plains indicate significant change occurred throughout the holocene which had profound impacts on playa ecosystem functions e g groundwater recharge surface water storage and habitat minimum 13c values and buried soils observed during the pleistocene holocene transition suggest sufficient moisture to support vegetative cover and promote pedogenesis low magnetic susceptibility rapid increase in 13c and weak pedogenic alteration in overlying deposits suggest early holocene aridity with increased landscape instability and sediment deposition early to middle holocene stratigraphy transitioned from loess with little pedogenic modification into overlying buri

holocene climatic and environmental changes in the arid and semi arid areas of china a review this paper reviews recently published literature most of which was published in chinese and searches for regional patterns of holocene changes useful in depicting global patterns the holocene in the xinjiang region can be divided into three stages a warming and dry early stage from 11 similar to 10 to 8 similar to 7 ka bp a warm and wet middle stage from 8 similar to 7 to 4 5 similar to 3 ka bp and a fluctuating cool and dry late stage since 4 5 similar to 3 ka bp the holocene in the northern tibetan plateau can also be divided into three stages a warming and wet stage from 10 5 similar to 10 to 5 similar to 4 ka bp followed by a variable drying and probably warm stage 5 similar to 4 to 3 ka bp and ending with a cool and dry stage since 3 ka bp in the inner mongolian plateau the early holocene from 10 5 similar to 9 5 to 8 similar to 7 5 ka bp was warming and dry and a warm and wet climate occurred from 7 5 to 3 5 during which the best time was 6 3 3 8 ka bp the climate has been variably drying and probably cooling since 3 5 ka bp in the northwestern part of the loess plateau several holocene palaeosols have been identified 10 9 7 5 5 4 3 and 2 7 2 ka bp with the 7 5 5 ka bp palaeosol being most strongly expressed the best developed palaeosol equivalent in major valleys is a swamp wetland facies deposited between 8885 and 3805 c 14 yr bp under an extremely wet regime the climate has fluctuated significantly at least three times around a dry and probably cool regime after the swamp wetland facies depositional period our summary shows that the holocene climatic optimum occurred nearly contemporaneously 8 5 ka bp at all sites in the xinjiang region in the inner mongolian plateau and in the northwestern part of the loess plateau a warming and wet early holocene 10 8 ka bp in the northern tibetan plateau is most likely related to high effective soil moisture resulting from snow and ice melting we propose here that the middle holocene climatic optimum 8 5 ka bp in arid to semi arid china was primarily a delayed response of the low latitude oceans to high latitude peak insolation 9 8 ka bp

geochemistry radiocarbon ages and paleorecharge conditions along a transect in the central high plains aquifer southwestern kansas usa abstract water samples from short screen monitoring wells installed along a 90 km transect in southwestern kansas were analyzed for major ions trace elements isotopes h b c n o s sr and dissolved gases he ne n2 ar o2 ch4 to evaluate the geochemistry radiocarbon ages and paleorecharge conditions in the unconfined central high plains aquifer the primary reactions controlling water chemistry were dedolomitization cation exchange feldspar weathering and o2 reduction and denitrification radiocarbon ages adjusted for c mass transfers ranged from 10 ka to reduce the average no3 concentration in recent recharge to the holocene background concentration

geomorphic and sedimentary responses of the bull creek valley southern high plains usa to pleistocene and holocene environmental change abstract fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions this study examines the response of bull creek a small ephemeral creek in the oklahoma panhandle to environmental conditions through the late pleistocene and holocene fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley based on their elevations terraces were broadly grouped into a late pleistocene fill terrace t3 and two holocene fill cut terrace sets t2 and t1 terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the younger dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late holocene the highest rates of aeolian accumulation within the valley occurred during the early to middle holocene our data provide significant new information regarding the late pleistocene and holocene environmental history for this region located between the well studied southern and central high plains of north america

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

radiocarbon and δ13c depth profiles of soil organic carbon in the u s great plains a possible spatial record of paleoenvironment and paleovegetation abstract soil profiles from undisturbed grassland sites around the great plains of the usa were sampled for analysis of soil organic carbon soc content radiocarbon age and stable carbon isotope composition 13 c with the exception of a few pronounced dating anomalies soc radiocarbon age generally increases steadily with depth back to 10 15 000 cal yr bp the deepest soil intervals in 9 of the 12 sites the radiocarbon ages were used to establish the chronology of changes in past plant distribution over time and space based on soc 13 c as an indicator of c 3 and c 4 plant abundance changes were referenced to an soc 13 c value of 20 which is the approximate mid point between c 3 and c 4 carbon isotope composition i e an equal mixture of c 3 and c 4 carbon prior to 10 000 cal yr bp the region was dominated by c 3 plants with the exception of the southernmost texas sites from 10 000 to 2000 cal yr bp c 4 plants expanded their range initially as a peninsula of c 4 predominant grasses extending northeastward and ultimately dominating all but the northernmost border of the region finally the c 3 predominant region re expanded after 1000 cal yr bp perhaps as a response to the little ice age cooling despite uncertainties associated with using radiocarbon dated soc depth profiles as a proxy the past c 3 and c 4 plant distribution inferred from soc 13 c conforms well to results from other paleoclimate proxies and differences may be helpful in targeting future research

episodic holocene loess deposition in central nebraska abstract the mirdan canal section in central nebraska usa provides evidence for multiple episodes of holocene loess deposition in the central great plains this irrigation canal cut exposes more than 4 m of holocene sediment that overlies the late wisconsinan peoria loess the oldest holocene sediment is local slopewash that fills gullies but overlying beds are interpreted as holocene loess bignell loess three buried soil profiles occur within the holocene sediment and have yielded uncalibrated 14 c ages of 3010 yr bp uppermost buried soil and 8790 yr bp third buried soil from top a fourth buried soil yielded an age of 9330 yr bp and is correlated with the brady soil the bignell loess has a darker color slightly more organic matter more clay more coarse silt and sand less smectite and less volcanic glass than the underlying peoria loess the bignell loess is most plausibly interpreted as dust from local flood plains containing a mixture of reworked peoria loess and older silts with contrasting mineralogy episodes of loess deposition occurred in the early middle and late holocene probably during periods of dry climate but possibly also as a consequence of large erosive floods that made wind erodible sediment available on nearby flood plains

lower cretaceous paleo vertisols and sedimentary interrelationships in stacked alluvial sequences utah usa the yellow cat member of the cedar mountain formation in poison strip utah usa consists of stacked erosionally bounded alluvial sequences dominated by massive mudstones lithofacies fm with paleo vertisols sediment bodies within these sequences grade vertically and laterally into each other at pedogenic boundaries across which color texture and structures sedimentary vs pedogenic change slickensides unfilled sealed cracks carbonate filled cracks and deeper cracks filled with sandstone the latter features suggest thorough desiccation during aridification thin sandstones sms in some sequences typically as well as laminated to massive mudstones flm with which they are interbedded in some cases are interpreted as avulsion deposits the termini of many beds of these lithofacies curve upward parallel to nearby pedogenic slickensides as the features we call turnups turnups are overlain or surrounded by paleosols but strata sheltered underneath beds with turnups retain primary sedimentary fabrics turnups were produced by movement along slickensides during pedogenesis by differential compaction alongside pre existing gilgai microhighs or by a combination of both palustrine carbonates lithofacies c appear only in the highest or next highest alluvial sequences along with a deep paleo vertisol that exhibits partially preserved microrelief at the base of the overlying poison strip member the attributes of the yellow cat member suggest comparatively low accommodation slow accumulation long hiatuses in clastic sedimentation and substantial time intervals of subaerial exposure and pedogenesis it appears to be distinct among the members of the cedar mountain formation in these respects

late quaternary redeposited loess soil developmental sequences south yemen abstract episodic desert loess and paleosol sequences in south yemen provide a late pleistocene to holocene record of climatic change and soil development at sana one paleosol based on its thickness and development formed during mid or early holocene time in approximately four thousand years the 2akb horizon sample of this paleosol has a 14 c age of 7750 300 years at ibb the 2abtb horizon of another paleosol has a 14 c age of 33 100 years deposition silt very fine sand clay for the sana site calculates to average 110 g m 2 yr 1 and includes 3 3 g or less of caco 3 m 2 yr 1 this rate of desert loess and carbonate deposition is probably 2 to 5 times greater than that in the lahontan basin of the united states during the last 13 kyr and about 2 to 5 times higher than that in the southwestern united states today it is about the same as the 12 cm kyr 1 170 g m 2 yr 1 estimated for central north iran and the 10 cm kyr 1 0 1 mm yr 1 estimated for the netivot section of the negev of israel but some 7 to 9 times less than the rate estimated for wisconsinan loess in iowa thickness of desert loess examined and the calculated rate of deposition indicate that the crater has been receiving desert loess for at least 15 kyr and that the crater is pre holocene pedogenic development of the camborthids and haplargids in the ground soils and that of the argillic horizons in the sana paleosols suggest that these soils formed in a somewhat more humid phase than the present warm tropical semi arid environment the occurrence of mollic epipedons in the sana paleosols but not in the ground soils is evidence of a more humid past climate mid or early holocene the ibb paleosol which formed at least partly during a more humid part of the late pleistocene is even more strongly developed than the mid or early holocene sana paleosols

comparison of a large scale inertia gravity wave as seen in the ecmwf analyses and from radiosondes 1 the location characteristics and evolution of a large scale inertia gravity wave that occurred in the lower stratosphere over the north of the british isles on february 6 1997 are studied numerous high resolution radiosondes were available at that time and in that region as part of the fastex database they reveal an intense large scale inertia gravity wave igw propagating upwards above the tropopause maps of the divergence of the horizontal wind on isentropic surfaces were obtained from the ecmwf analyses and showed a clear pattern of alternating bands of convergence and divergence at the lower stratospheric heights in the same geographical region and starting at the same time the comparison of the characteristics of this igw in the analyses and in the observations suggests that the ecmwf analyses can be used for qualitative indications regarding the locations most favorable to large scale igw generation and the corresponding orientation of the waves

coincidence and spatial variability of geology soils and vegetation mill run watershed virginia the mill run watershed is a structurally controlled synclinal basin on the eastern limb of the massanutten mountain complex of northwestern virginia bedrock contacts are obscured by coarse sandstone debris from exposures near basin divides colluvium blankets more than half the basin masking geomorphic surfaces affecting vegetation patterns and contributing to the convexity of the alluvial terrace pediment and erosion surfaces examination of the bedrock geology geomorphology soils and vegetation shows distinct distributional correspondences vegetation is strongly interdependent with geomorphology bedrock geology and soils on convex colluvial slopes mixed hardwood forests are most common in concave coves and deep gorges mixed hardwoods are replaced by conifers in thin colluvium in poorly developed soils and on blockfields chestnut oak is singularly prevalent conifers dominate shaley bedrock areas soils and suficial sediments have a major effect on near surface hydrology during wet seasons cemented horizons in the subsurface cause temporary saturation in the superjacent horizons lateral movement of soil water effectively eliminates a vertical component of ground water recharge vegetation is strongly dependent on water availability and thus reflects the distribution of subsurface barriers and sediment soil facies changes

radiosonde observations of equatorial atmosphere dynamics over indonesia 2 characteristics of gravity waves this paper discusses the characteristics of gravity waves in the equatorial region revealed by analyzing radiosonde measurements of wind velocity and temperature fluctuations at 0 35 km with a height resolution of 150 m made every 5 7 hours between february 27 and march 22 1990 in east java indonesia we conducted hodograph analysis to delineate vertical and horizontal propagation characteristics and found that most gravity waves were generated in the middle of the troposphere and that they propagated upward into the stratosphere the amplitudes of wind velocity and temperature fluctuations due to gravity waves were larger in the stratosphere than in the troposphere the direction of horizontal propagation of gravity waves was rather uniformly distributed in the troposphere but it became eastward in the lower stratosphere being opposite to that of the mean winds because of quasi biennial oscillation the vertical wavenumber spectra of wind velocity were described fairly well by a saturated model spectrum although their amplitudes were smaller in the stratosphere a typical vertical wavelength was 2 2 5 km while the horizontal phase velocities were 5 7 and 12 m s in the troposphere and stratosphere respectively the amplitudes of small scale gravity waves were significantly larger in the equatorial stratosphere than at middle latitudes time height variation of the wind velocity variance due to gravity waves showed a clear correlation with that for high relative humidity which implies that cloud convection is an important mechanism of gravity wave generation in the equatorial region

radiosonde observations of equatorial atmosphere dynamics over indonesia 1 equatorial waves and diurnal tides this paper describes the characteristics of the mean winds equatorial waves with periods ranging from 4 to 20 days and diurnal tides determined by analyzing the profiles of wind velocity temperature and humidity obtained every 5 7 hours in the height range up to about 35 km with a height resolution of 150 m during an observation campaign conducted february 27 to march 22 1990 in east java indonesia the structures of the mean winds in the troposphere and lower stratosphere seemed to be affected by the australian monsoon and the quasi biennial oscillation respectively frequency spectra indicated that the equatorial waves as well as the diurnal tides were dominant below about 25 km while gravity waves with periods shorter than 4 days became more significant above 25 km a 7 day oscillation showing an antiphase relation between the eastward and northward components and exhibiting large amplitudes was observed in the lower troposphere the time height variations of the activity of this 7 day oscillation were clearly correlated with a region of high relative humidity perturbations in the zonal wind and temperature with wave periods varying from 15 to 17 days were also enhanced in the troposphere while kelvin waves with periods of about 7 and 20 days were detected in the lower stratosphere and activity near the tropopause was conspicuously enhanced we found that the 20 day kelvin wave greatly modified the structure of the tropopause such as the minimum temperature the tropopause height and the values of the brunt vaisala frequency squared n2 which further suggests the effects of kelvin waves on the transportation of tropospheric water vapor into the stratosphere and on the downward mixing of stratospheric minor constituents into the troposphere the observed profiles of the diurnal oscillation were compared with those of a numerical model assuming only migrating tides which reasonably agreed above about 25 km below 25 km however the observed amplitudes were 1 1 5 m s exceeding those of the model about 10 times moreover the phase profiles involved fluctuations with small vertical scales suggesting interference by many nonmigrating tides with short vertical wavelengths

human responses to middle holocene altithermal climates on the north american great plains abstract the climate of the great plains during the middle holocene varied considerably but overall it was marked by a north south gradient of increasingly warmer and drier conditions with a reduction in effective moisture surface water and resource abundance and an increase in resource patchiness sediment weathering erosion and aeolian activity pronounced drought conditions were most evident on the southern high plains understanding the human responses to middle holocene climates is complicated by a lack of archaeological data which is partly a result of geomorphic processes that removed or deeply buried sites of this age and by the varying adaptive responses of hunter gatherers during this period on the southern high plains where drought was most severe surface and groundwater sources dried and bison populations were diminished prompting substantial adaptive changes including local abandonment well digging to tap underground water and a widening of the diet breadth to incorporate higher cost lower return seed and plant resources sites of this age on the central and northern plains also show a possible increase in diet breadth with the incorporation of plant foods in the diet and perhaps changes in settlement mobility including possible shift into higher elevation areas or mapping on to extant rivers and springs but linking those changes to middle holocene drought is less straightforward

gravity wave forcing in the stratosphere observational constraints from the upper atmosphere research satellite and implications for parameterization in global models 1 global models that include parameterized gravity wave effects have an excessively broad range of tuning parameters to choose from that allow a very broad range of gravity wave momentum forcing distributions we derive a set of constraints on gravity wave characteristics near the tropopause from databased estimates of gravity wave effects in the stratosphere we use 5 6 years of upper atmosphere research satellite data and uk met office analyzed wind and temperature fields to first derive estimates of the gravity wave mean flow forcing in the stratosphere we then compare these estimates to a suite of gravity wave model calculations to infer the constraints on the gravity wave characteristics near the tropopause these constraints apply to the portion of the gravity wave spectrum that dissipates in the stratosphere and does not include those that dissipate and drive the mesosphere we focus on equatorial and extratropical regions separately and find substantially different wave characteristics between the two we also find a seasonal variation in gravity wave characteristics in the extratropics near the equator gravity waves assist in driving the quasibiennial and semiannual oscillations and our constraints on gravity waves likely include a blend of characteristics of both ordinary gravity waves and some kelvin wave modes in the extratropics gravity wave forcing primarily assists in the annual winter to summer transition from westward to eastward winds

geochemical and mineralogical evidence from eolian sediments for northwesterly mid holocene paleowinds central kansas usa a prominent 4500 km2 dune eld in the great plains is the great bend sand prairie of south central kansas dunes here overlie late quaternary alluvium and were reactivated extensively in the late holocene geomorphic and soil evidence suggests that the most likely eolian sand source is the arkansas river valley to the northwest nevertheless orientations of stabilized dunes indicate that the most recent dune forming winds came from the south or southwest in agreement with modern wind data mineralogy and trace element concentrations in eolian sands of the great bend sand prairie are similar to those of the arkansas river which permits the arkansas river as a sediment source ca and sr abundances which re ect small amounts of carbonate minerals are higher in arkansas river sand compared to eolian sands and show a systematic depletion away from the arkansas river to the southeast these trends are likely due to carbonate mineral depletion downwind from abrasion and size reduction thus paleowinds probably were northwesterly during initial deposition northwesterly winds occur today when dry paci c derived air is dominant we hypothesize that the residence time of this air mass was much greater while dunes initially formed possibly during a warmer and drier mid holocene period 2000 elsevier science ltd and inqua all rights reserved