holocene loess in illinois revealed by osl dating implications for stratigraphy and geoarchaeology of the midwest united states abstract most uplands in illinois are blanketed by late wisconsinan peoria loess and the conventional wisdom is that little or no dust accumulation occurred during the holocene 11 7 ka to present in a recent effort to investigate if illinois holocene loess was deposited and preserved we applied optically stimulated luminescence osl dating to seven locations where loess is thick these include four sites along the mississippi river in westernmost illinois and three loess bluffs south of the illinois river in central illinois our results suggest that holocene aged loess is preserved along the mississippi river in the state of illinois in contrast no holocene loess was found south of the illinois river in the central portion of the state in addition to its spatially limited distribution holocene loess thicknesses range only up to 1 m nevertheless loess stratigraphy and osl dating results provide the first holocene loess reported east of the missouri river our new finding also resolves the long time archeological puzzle that a number of artifacts of several thousand years old were buried by upland loess along the mississippi river

a measurement of lunar tides in the mesosphere at adelaide south australia wind measurements at adelaide 35 s at heights from 76 to 98 km are analyzed for semidiurnal or semimonthly lunar tides two data sets are used one of about 2 years 1984 1985 and one of 1 year 1986 the lunar tide amplitude generally has its largest values at the equinoxes though this pattern changes in 1984 1985 at the greatest heights to solstice maxima especially in winter july diurnal average amplitudes reach 4 m s 1 while the largest value obtained was 8 m s 1 inferred vertical wavelengths of the propagating tides were rather variable and there was evidence of possible mode coupling and interference in summer wavelengths of 25 km occurred below 92 km and were evanescent above while in winter long wavelengths were found in the 78 to 90 km range with shorter 38 km wavelengths above that height comparisons of phases with results from saskatoon and kyoto suggest that around 95 km antisymmetric modes may be dominant in june and december and symmetric modes in february diurnal variations in the lunar tide were evident and year to year changes were seen in some aspects comparison with currently available models shows several points of disagreement

a calculation of ionospheric currents due to semidiurnal antisymmetric tides the fully developed equivalent circuit method is used to calculate the ionospheric electric current flow due to the 2 3 and 2 5 tidal modes the 2 5 mode currents are of negligibly small amplitude the 2 3 current pattern has meridional currents in the same direction at a given local time in both north and south hemispheres there is also sometimes a minimum in the zonal current around 10 degree dip latitude and the equatorial electrojet pattern may be different in different longitude zones these features may be possible explanations of 1 the meridional current pattern observed at saint santin 2 current flows on abnormal quiet days aqds 3 the reverse equatorial electrojet 4 the seasonal phase anomaly in the lunar geomagnetic tide and 5 the invasion of one hemisphere s current pattern by that from the opposite hemisphere the recent detection of antisymmetric semidiurnal winds just below the dynamo region further demonstrates the importance of these modes

distribution of groundwater seepage to large surface water bodies the effect of hydraulic heterogeneities abstract at 26 sites on the upper great lakes and their connecting channels where groundwater seepage measurements have been made seepages decrease continually offshore at only seven 26 instead 17 63 of the sites have offshore seepages which substantially exceed those at some locations closer to shore the distributions fall into two consistent patterns one where a nearshore decrease in seepage with increasing distance is succeeded offshore by an increase and a second where nearshore seepages are relatively constant and then increase farther offshore the patterns have been observed in two independent studies using two totally different seepage meter designs and emplacement methods and are attributed to hydrogeologic heterogeneities beneath the surface water body detailed marine geophysical measurements at seven sites on green bay show that the anomalously high offshore seepages there are associated with local thinning of the relatively low hydraulic conductivity glacial sediments separating the bay from the underlying aquifer a fractured dolomite at these locations heterogeneity in sediment thickness is a stronger factor in causing seepage anomalies than is heterogeneity of either sediment or bedrock hydraulic conductivity insufficient information exists to confirm a parallel cause effect relation at the other sites but evidence points in that direction similar seepage anomalies have been observed at other smaller lakes by other researchers but never with this frequency it is argued that the cause of the difference is the size of the great lakes seepage occurs and measurements have been made over much greater offshore distances than in smaller lakes and the likelihood that heterogeneities will occur within the zone of measurement is thus also much greater

characterization of lake water and ground water movement in the littoral zone of williams lake a closed basin lake in north central minnesota williams lake minnesota is a closed basin lake that is a flow through system with respect to ground water ground water input represents half of the annual water input and most of the chemical input to the lake chemical budgets indicate that the lake is a sink for calcium yet surficial sediments contain little calcium carbonate sediment pore water samplers peepers were used to characterize solute fluxes at the lake water ground water interface in the littoral zone and resolve the apparent disparity between the chemical budget and sediment data pore water depth profiles of the stable isotopes 18o and 2h were non linear where ground water seeped into the lake with a sharp transition from lake water values to ground water values in the top 10 cm of sediment these data indicate that advective inflow to the lake is the primary mechanism for solute flux from ground water linear interstitial velocities determined from 2h profiles 316 to 528 cm yr were consistent with velocities determined independently from water budget data and sediment porosity 366 cm yr stable isotope profiles were generally linear where water flowed out of the lake into ground water however calcium profiles were not linear in the same area and varied in response to input of calcium carbonate from the littoral zone and subsequent dissolution the comparison of pore water calcium profiles to pore water stable isotope profiles indicate calcium is not conservative based on the previous understanding that 40 50 of the calcium in williams lake is retained the pore water profiles indicate aquatic plants in the littoral zone are recycling the retained portion of calcium the difference between the pore water depth profiles of calcium and 18o and 2h demonstrate the importance of using stable isotopes to evaluate flow direction and source through the lake water ground water interface and evaluate mechanisms controlling the chemical balance of lakes published in 2003 by john wiley sons ltd

fate and groundwater impacts of produced water releases at osper b site osage county oklahoma abstract for the last 5 a the authors have been investigating the transport fate natural attenuation and ecosystem impacts of inorganic and organic compounds in releases of produced water and associated hydrocarbons at the osage skiatook petroleum environmental research osper a and b sites located in ne oklahoma approximately 1 0 ha of land at osper b located within the active branstetter lease is visibly affected by salt scarring tree kills soil salinization and brine and petroleum contamination site b includes an active production tank battery and adjacent large brine pit two injection well sites one with an adjacent small pit and an abandoned brine pit and tank battery site oil production in this lease started in 1938 and currently there are 10 wells that produce 0 2 0 5 m3 d 1 3 bbl d oil and 8 16 m3 d 50 100 bbl d brine geochemical data from nearby oil wells show that the produced water source is a na ca cl brine 150 000 mg l tds with high mg but low so4 and dissolved organic concentrations groundwater impacts are being investigated by detailed chemical analyses of water from repeated sampling of 41 boreholes 1 71 m deep the most important results at osper b are 1 significant amounts of produced water from the two active brine pits percolate into the surficial rocks and flow towards the adjacent skiatook reservoir but only minor amounts of liquid petroleum leave the brine pits 2 produced water brine and minor dissolved organics have penetrated the thick 3 7 m shale and siltstone units resulting in the formation of three interconnected plumes of high salinity water 5000 30 000 mg l tds that extend towards the skiatook reservoir from the two active and one abandoned brine pits and 3 groundwater from the deep section of only one well br 01 located 330 m upslope and west of the site appear not to be impacted by petroleum operations

effect of anisotropy and groundwater system geometry on seepage through lakebeds 1 analog and dimensional analysis abstract distribution of seepage through lakebeds is controlled partly by geometric configuration of the lake and of the groundwater system interacting with the lake to evaluate the effect of these factors conductive paper electric analog models were used to analyze a number of lake and groundwater settings having different geometric configurations most settings analyzed are of lakes that do not penetrate the groundwater system the width ratio the ratio of half the lake width to thickness of the groundwater system is the principal geometric characteristic used in this study because the distribution of groundwater seepage into a lake is not uniform across the lakebed the concept of a streamlinecrowding factor is developed and is used to determine seepage patterns from geometric characteristics of the lake and its contiguous groundwater system analysis of fourteen different width ratios of lake and groundwater systems indicates that lakes can be defined by three general groups of seepage patterns which include flow patterns volumes and rates 1 lakes having width ratios less than 0 6 show relatively uniform distribution of seepage across the lakebed 2 lakes having width ratios of 0 6 to 2 0 change in absolute and relative streamline crowding in the near shore region and 3 lakes having width ratios greater than 2 0 show stable flow patterns near shore however with increasing lake width the relative streamline crowding increases relative to that width for deep lakes and those in anisotropic media the crowding effect is decreased resulting in more uniform seepage across the lakebed

influence of solar and lunar tides on the mesopause region as observed in polar mesosphere summer echoes characteristics long term observations of polar mesosphere summer echoes pmse from 2002 to 2012 are investigated with the aim to statistically study the effects of solar thermal migrating and lunar gravitational tides on aerosol layers and their environment at altitudes 80 90 km the solar and lunar tidal periodicities are clearly present in pmse data for the first time both amplitudes and phases of solar and lunar tides are estimated using pmse data from the esrad radar located at esrange sweden the diurnal semidiurnal and terdiurnal solar migrating tides show pronounced periodicities in the pmse strength and wind velocity components lunar tides demonstrate clear oscillations in the pmse strength and wind velocities as well canonical lunar gravitational tides corresponding to the lunar gravitational potential produce rather large amplitudes and are comparable to the solar thermal tides whereas noncanonical lunar oscillations have minor effects on pmse layers but are still statistically significant the influence of diurnal semidiurnal tides and monthly semimonthly tidal components is studied separately our estimations of solar thermal and lunar tidal amplitudes are in good agreement with those of previous model and experimental studies a new mechanism of quadratic demodulation of the solar semidiurnal and lunar semidiurnal tides is shown to be valid at the summer mesopause and can explain periodical pmse oscillations due to the lunar synodic semimonthly tide with period of 14 77 days two harmonics with periods of 27 0 and 13 5 days supposedly representing the solar rotation cycle are also clearly present in pmse data

average equatorial zonal and vertical ion drifts determined from san marco d electric field measurements san marco d electric field measurements have been averaged in terms of their equivalent ion drift to produce an average pattern of equatorial zonal and vertical ion drifts variations with season solar activity kp lunar phase and longitude have been analyzed similarities and some differences from previous jicamarca de 2 and ae e results are seen confirmation is given of the dominance of the f region dynamo in the 1900 2100 local time region the daytime zonal ion drift is larger for high f10 7 values than that for low values there is little variation between high and low values of kp superrotation is evident in this data set and is larger at equinox compared to solstice at the june solstice there are significant differences between the average ion drifts in the longitude sector where the geomagnetic equator is north of the geographic equator indian sector and the sector where the geomagnetic equator is south of the geographic equator peruvian sector the daytime upward velocity is larger in the indian sector than in the peruvian sector and it reverses later in the evening in the indian sector daytime westward zonal velocities are larger and the nighttime eastward velocities are smaller in the indian sector a presunrise enhancement is seen in the downward velocity in the indian sector but not in the peruvian sector significant variations are also seen with the phase of the moon in light of current theory the lunar variations suggest a complex interaction of e and f region dynamo sources with conductivity changing in phase and character with latitude

lunar tides in the thermosphere ionosphere electrodynamics general circulation model lunar semidiurnal tides are introduced at the lower boundary of the national center for atmospheric research thermosphere ionosphere electrodynamics general circulation model tiegcm the tides are derived from the model of vial and forbes 1994 and interesting properties of these tides are found when they are subjected to hough decomposition there is considerable hemispherical antisymmetry in the september tides and the march and september modal compositions are significantly different a differencing method is used to isolate the lunar tidal effects in the tiegcm and these are compared with lunar tidal analyses of ionospheric data the model reproduces the broad features of the lunar tide in f0f2 maximum frequency of the f region with phase changes around 7 magnetic dip latitude during daytime the model and data analysis both give variations of the amplitude and phase of the lunar tide with local time near the equator the variation of phase with local time changes with latitude as the equatorial anomaly develops during the day comparison between the model predictions and analyses of data at observatories at midlatitudes produces mixed results here the effects of the lunar components of both electrodynamic drifts and of neutral winds need to be taken into account several cases of day to night changes in the phase of the lunar tide in f0f2 are noted large nighttime amplitudes of the lunar tide in hmf2 height of the maximum density more than 4 km seem to be due to inphase action of the electrodynamic and neutral wind effects while during daytime they are out of phase the lunar tide in the ratio of oxygen to nitrogen density o n2 is estimated and found to be of relatively minor importance amplitudes of the lunar tide in f0f2 may be measured at more than 0 4 mhz at some local times but the model values are less than this comparison is also made with ion drift measurements made by the san marco d satellite the several uncertainties which underlie this work are discussed in detail

a new method to constrain soil development time using both osl and radiocarbon dating abstract the time over which a soil has developed since the parent materials were deposited and subaerially exposed referred to here as soil development time is of considerable interest to pedologists geomorphologists geologists archeologist and paleoclimatologists soil development time has been estimated both indirectly based on the degree of soil development and directly by radiocarbon dating of soil organic matter optically stimulated luminescence osl dating of parent material deposition and through exposure dating using cosmogenic nuclides here we propose a new model for estimating the soil development time by subtracting the low molecular weight lmw or pyrolysis volatile 14c age of the uppermost a horizon of a soil from the osl age of the c horizon of the parent material soil time osl age parent c horizon 14c age lmw fraction of uppermost a horizon the lmw organic compound fraction represents the most mobile carbon compounds in the soil organic carbon pool and is least resistant to physical chemical and biodegradation in the soil environment potentially yielding the youngest 14c age osl dating of the c horizon provides an estimate of the time since deposition of unconsolidated parent material thus the difference in the two ages can be used to estimate the time that has elapsed for pedogenic alteration from deposition of the parent material to the most recent additions of soil organic carbon we applied this new approach in four scenarios 1 in a modern soil that developed downward in loess 2 in a buried soil developed in aggrading loess a cumulative soil which grows upward 3 in a buried soil formed in dune sand and 4 in a counterexample showing that simple subtraction is not always appropriate because of changes in soil s parent materials from loess to sand these case studies reveal that this approach constrains soil development time more reasonably than can be commonly done with either osl or radiocarbon dating alone the difference in 14c ages between the uppermost and lowermost sola of a soil profile almost certainly underestimates the time of soil development and the difference in osl ages taken from sediment units overlying and underlying a buried soil most likely overestimates it a combination of osl and radiocarbon dating better constrains soil development time broadening the applications of these two dating methods beyond their use for cross checking the accuracy of the other dating method

composition of pore water in lake sediments research site b osage county oklahoma implications for lake water quality and benthic organisms abstract shallow ground water at us geological survey research site b in northeastern oklahoma is contaminated with nacl rich brine from past and present oil production operations contaminated ground water provides a potential source of salts metals and hydrocarbons to sediment and water of adjacent skiatook lake a former brine storage pit 10 m in diameter that is now submerged just offshore from site b provides an additional source of contamination cores of the upper 16 40 cm of lake sediment were taken at the submerged brine pit near an offshore saline seep and at a location containing relatively uncontaminated lake sediment pore waters from each 2 cm interval were separated by centrifugation and analyzed for dissolved anions cations and trace elements high concentrations of dissolved cl in pore waters 200 5000 mg l provide the most direct evidence of contamination and contrast sharply with an average value of only about 37 mg l in skiatook lake chloride br mass ratios of 220 240 in contaminated pore waters are comparable to values in contaminated well waters collected onshore dissolved concentrations of se pb cu and ni in cl rich pore waters exceed current us environmental protection agency criteria for probable toxicity to aquatic life at the submerged brine storage pit the increase of cl concentration with depth is consistent with diffusion dominant transport from deeper contaminated sediments near the offshore saline seep pore water cl concentrations are consistently high and vary irregularly with depth indicating probable cl transport by layer directed advective flow estimated annual contributions of cl to the lake from the brine storage pit 20 kg and the offshore seep 9 kg can be applied to any number of similar sources generous estimates of the number of such sources at site b indicate minimal impact on water quality in the local inlet of skiatook lake similar methodologies can be applied at other sites of nacl contamination surrounding skiatook lake and elsewhere

longitudinal variation of the lunar tide in the equatorial electrojet the atmospheric lunar tide is one known source of ionospheric variability the subject received renewed attention as recent studies found a link between stratospheric sudden warmings and amplified lunar tidal perturbations in the equatorial ionosphere there is increasing evidence from ground observations that the lunar tidal influence on the ionosphere depends on longitude we use magnetic field measurements from the champ satellite during july 2000 september 2010 and from the two swarm satellites during november 2013 february 2017 to determine for the first time the complete seasonal longitudinal climatology of the semidiurnal lunar tidal variation in the equatorial electrojet intensity significant longitudinal variability is found in the amplitude of the lunar tidal variation while the longitudinal variability in the phase is small the amplitude peaks in the peruvian sector 285 e during the northern hemisphere winter and equinoxes and in the brazilian sector 325 e during the northern hemisphere summer there are also local amplitude maxima at 55 e and 120 e the longitudinal variation is partly due to the modulation of ionospheric conductivities by the inhomogeneous geomagnetic field another possible cause of the longitudinal variability is neutral wind forcing by nonmigrating lunar tides a tidal spectrum analysis of the semidiurnal lunar tidal variation in the equatorial electrojet reveals the dominance of the westward propagating mode with zonal wavenumber 2 sw2 with secondary contributions by westward propagating modes with zonal wavenumber 3 sw3 and 4 sw4 eastward propagating waves are largely absent from the tidal spectrum further study will be required for the relative importance of ionopsheric conductivities and nonmigrating lunar tides

a 10 000 year record of dune activity dust storms and severe drought in the central great plains dune fi elds and loess deposits of the great plains of north america contain stratigraphic records of eolian activity that can be used to extend the short observational record of drought we present a 10 000 yr reconstruction of dune activity and dust production in the central great plains region based on 95 optically stimulated luminescence ages the integration of data from both eolian sand and loess is an important new aspect of this record clusters of ages defi ne episodes of extensive eolian activity which we interpret as a response to frequent severe drought at 1 0 0 7 ka and 2 3 4 5 ka with peaks centered on 2 5 and 3 8 ka sustained eolian activity occurred from 9 6 to 6 5 ka parts of this record may be consistent with hypotheses linking holocene drought to sea surface temperature anomalies in the pacifi c or atlantic oceans or to the el nino southern oscillation phenomenon but the record as a whole is diffi cult to reconcile with any of these hypotheses

isotopic and rock magnetic expression of environmental change at the pleistocene holocene transition in the central great plains abstract in a region too dry for the effective use of the traditional palynological approach loess deposits of the central great plains offer a source of proxy information for the reconstruction of past climates the brady soil a ubiquitous feature developed within the uppermost late pleistocene peoria loess recorded the character of vegetation change associated with climate shifts during the pleistocene holocene transition stable carbon isotope ratio analysis and two room temperature magnetic parameters were used to examine the nature of the change during this period 13 c values derived from soil organic matter indicate that in the late pleistocene minor populations of drought tolerant c4 plants were interspersed among the dominant cool season grasses c3 in the west while c3 grasses were accompanied by trees in the east by the early holocene c4 grasses were the dominant vegetation in the west and contributed substantially to the 13 c signal in the east magnitude of the 13 c shift suggests an increase in july mean daily temperature of 8 10 c according to existing models magnetic susceptibility and frequency dependence signal the cessation of loess deposition and development of the brady soil and indicate a spatial pattern in the intensity of weathering across the region

a diurnal modulation of the lunar tide in the upper atmosphere analysis of geomagnetic data from several stations in the equatorial region shows that the amplitude of the lunar semimonthly tide frequently does not have the expected symmetry about noon in its diurnal variation there is a distinct tendency for larger amplitudes in the morning at many stations this effect is largest in equinoctial months though there are regional differences analysis of data from different years confirms its presence the interaction between solar and lunar tides in the middle atmosphere may be responsible for the observed modulation

lunar tidal winds measured in the upper atmosphere 78 105 km at saskatoon canada abstract six years of winds data measured by the partial reflection drifts technique have been analyzed for lunar tides data are available at 3 km intervals of height and are separately analyzed in two year datasets to cheek consistency a month by month seasonal variation is derived largest amplitudes of the lunar tide occur in january february with a smaller maximum in summer the vertical wavelength is longest in summer and the tide then resembles that predicted for a pure 2 2 mode in winter vertical wavelengths range from 25 to 81 km in different years several of these results do not agree with the model of forbes an o1 component of the lunar tide could not be detected

effect of anisotropy and groundwater system geometry on seepage through lakebeds 2 numerical simulation analysis abstract the interaction of lakes and groundwater is controlled partly by the geologic framework through which the water flows two interrelated geometric factors of the groundwater system that affect flow are overall geometry of the system and anisotropy of the porous media within the system numerical simulation analysis was made for variations in the coefficient of anisotropy for each of several lake and groundwater settings having different geometric configurations these analyses indicate that for a given geometric setting as the anisotropy of geologic materials decreases seepage from a lake decreases and depth of the local groundwater flow system associated with the lake increases transformation of scale of groundwater systems that have anisotropic media to isotropic equivalents results in a change in the overall geometry because of the different slopes of the water table and lakebed resulting from the scale transformations a series of numerical experiments were made for various geometric configurations for a given anisotropy these analyses indicate that as thickness of the groundwater system decreases relative depth of the local flow system increases and seepage from the lake decreases

optical ages on loess derived from outwash surfaces constrain the advance of the laurentide ice sheet out of the lake superior basin usa abstract we present textural and thickness data on loess from 125 upland sites in west central wisconsin which confirm that most of this loess was derived from the sandy outwash surfaces of the chippewa river and its tributaries which drained the chippewa lobe of the laurentide front during the wisconsin glaciation mis 2 on bedrock uplands southeast of the widest outwash surfaces in the chippewa river valley this loess attains thicknesses 5 m osl ages on this loess constrain the advance of the laurentide ice from the lake superior basin and into west central wisconsin at which time its meltwater started flowing down the chippewa drainage the oldest mar osl age 23 8 ka from basal loess on bedrock agrees with the established but otherwise weakly constrained regional glacial chronology basal ages from four other sites range from 13 2 to 18 5 ka pointing to the likelihood that these sites remained geomorphically unstable and did not accumulate loess until considerably later in the loess depositional interval other osl ages from this loess taken higher in the stratigraphic column but below the depth of pedoturbation range to nearly 13 ka suggesting that the chippewa river valley may have remained a loess source for several millennia

chemical and particle size evidence for addition of fine dust to soils of the midwestern united states significant long term atmospheric dust additions to soils are well documented in many parts of the world but not in the midwestern united states we investigated elemental mass fluxes associated with soil development in late wisconsinan loess in illinois and minnesota using zr as a stable index element positive mass fluxes of al fe and ti can most plausibly be explained by additions to these soils of fine far traveled dust with higher al zr fe zr and ti zr ratios than the coarser locally derived loess high resolution particle size analyses support this explanation the proposed dust influx will complicate efforts to quantify weathering processes in these soils far traveled dust influx could have occurred simultaneously with the final phase of local loess deposition and or later in the holocene depending on the timing of dust influx many other soils of the region may have been affected by it

evidence supporting holocene loess in illinois with new proxy data and historical regional perspectives on loess deposition in the upper mississippi river valley abstract we thank grimley et al 2019 for their constructive comments on our publication on holocene loess in illinois revealed by optically stimulated luminescence osl dating miao et al 2018 in the journal quaternary science reviews their skepticism on the preservation of holocene loess in illinois provides us with a good opportunity to clarify several key issues pedoturbation including bioturbation the methodology of soil research and our osl dating results in addition we will discuss the more fundamental issue behind this debate what controls loess deposition in the midwestern usa direct glacial sediment supply or broader scale climate change finally we also report new high resolution grain size magnetic susceptibility and color data from one of our holocene loess sites

on modeling migrating solar tides recent updates and extensions to a steady state two dimensional linearized model of global scale atmospheric waves have facilitated improved calculations of the subset of those waves which are subharmonics of a solar day and propagate with the apparent motion of the sun the model improvements are briefly described and some updated predictions of the migrating solar diurnal component are highlighted the latter represent the first numerical modeling effort to examine the seasonal variability of the migrating diurnal harmonic as it propagates into the mesosphere and lower thermosphere

lunar tidal winds in the upper atmosphere over jakarta 1 winds have been measured at heights from 70 to 120 km by means of a meteor wind radar near jakarta 6 4s 106 7e from 1993 to 1997 these data have been analysed for the lunar semidiurnal tide using a least squares fitting method generally lunar tidal amplitudes in the winds are about 2 m s 1 though the northward wind amplitude reaches 6 m s 1 in southern summer variations with height and season are shown and compared with the global scale wave model gswm often the agreement with the model is good but there is a difference in phase of the eastward wind in southern winter the gswm predicts a more rapid increase in northward wind magnitude with height than is observed year to year changes are examined for different seasons and these reveal sometimes consistent results and sometimes a variation in phase from year to year often the phase relations between eastward and northward winds at jakarta are more characteristic of a northern hemisphere tide as predicted by classical tidal theory particularly in southern spring and summer

lunar tide in the equatorial f region vertical ion drift velocity vertical ion drift velocity data from jicamarca have been analyzed for a lunar semidiurnal tide using a least squares fitting method amplitudes of up to 6 m s 1 are obtained with phases in agreement with lunar tidal determinations of other associated physical parameters variations between season solar activity and day to night are also examined generally amplitudes are larger in the southern summer much of the phase variation with season is very similar for solar maximum and minimum years there is a summer to winter phase change that is most distinct at solar maximum nighttime a day to night phase reversal can also been seen in some seasons hints of this are also found in the lunar tide in the f region height and in the magnetic variations at huancayo

lunar tide in the equatorial electrojet in relation to stratospheric warmings 1 the relationship between sudden stratospheric warmings ssws and large amplitude lunar tides in the equatorial electrojet eej is studied analysis of ground magnetometer data shows that the lunar tide in the eej is maximum during the northern winter season except in the pacific ocean region since ssws are also a northern winter phenomenon it is suggested that the relation between the large lunar tide in the eej and the ssw may possibly be coincidental the lunar tide in the geomagnetic variations at huancayo is anomalously large compared with other eej stations an examination of geomagnetic variations at eej stations during ssw events shows that afternoon counter electrojets are frequently present at new moon and full moon though the relationship is sometimes broken the observation of large lunar eejs when no ssw is present and of various different delay times suggests that other atmospheric processes are likely to be in play

loess record of the pleistocene holocene transition on the northern and central great plains usa various lines of evidence support conflicting interpretations of the timing abruptness and nature of climate change in the great plains during the pleistocene holocene transition loess deposits and paleosols on both the central and northern great plains provide a valuable record that can help address these issues a synthesis of new and previously reported optical and radiocarbon ages indicates that the brady soil which marks the boundary between late pleistocene peoria loess and holocene bignell loess began forming after a reduction in the rate of peoria loess accumulation that most likely occurred between 13 5 and 15 cal ka brady soil formation spanned all or part of the bolling allerod episode approximately 14 7 12 9 cal ka and all of the younger dryas episode 12 9 11 5 cal ka and extended at least 1000 years beyond the end of the younger dryas the brady soil was buried by bignell loess sedimentation beginning around 10 5 9 cal ka and continuing episodically through the holocene evidence for a brief increase in loess influx during the younger dryas is noteworthy but very limited most late quaternary loess accumulation in the central great plains was nonglacigenic and was under relatively direct climatic control thus brady soil formation records climatic conditions that minimized eolian activity and allowed effective pedogenesis probably through relatively high effective moisture optical dating of loess in north dakota supports correlation of the leonard paleosol on the northern great plains with the brady soil thick loess in north dakota was primarily derived from the missouri river floodplain thus its stratig raphy may in part reflect glacial influence on the missouri river nonetheless the persistence of minimal loess accumu lation and soil formation until 10 cal ka at our north dakota study site is best explained by a prolonged interval of high effective moisture correlative with the conditions that favored brady soil formation burial of both the brady soil and the leonard paleosol by renewed loess influx probably represents eolian system response that occurred when gradual change toward a drier climate eventually crossed the threshold for eolian activity overall the loess paleosol sequences of the central and northern great plains record a broad peak of high effective moisture across the late pleistocene to holocene boundary rather than well defined climatic episodes corresponding to the bolling allerod and younger dryas episodes in the north atlantic region

sources and paleoclimatic significance of holocene bignell loess central great plains usa abstract this paper reexamines the stratigraphy sources and paleoclimatic significance of holocene bignell loess in the central great plains a broadly similar sequence of loess depositional units and paleosols was observed in thick bignell loess sections up to 300 km apart suggesting that these sections record major regional changes in the balance between dust deposition and pedogenesis new optical ages together with previously reported radiocarbon ages indicate bignell loess deposition began 9000 11 000 yr ago and continued into the late holocene some bignell loess is

lunar tidal winds at adelaide and saskatoon at 80 to 100 km heights 1985 1990 winds data from the two sites were analyzed for lunar tides in 2 year groups the variation with height of the phase and amplitude of the tide showed considerable variability from year to year yet in general seasonal variations at particular heights were similar to those determined previously phases of the tide at the two sites were compared in order to estimate whether the tide was symmetric or antisymmetric for this purpose it was found necessary to use only 1 year data sets the predominance of symmetric tides during solstice months and antisymmetric tides at the equinox came as a surprise yet the result is in broad agreement with phase relations of the lunar geomagnetic tide

lunar tides in total electron content over brazil using data from global navigation satellite systems dual frequency receivers the lunar tides were studied in the ionospheric total electron content tec over brazil from 2011 to 2014 in order to calculate the amplitudes and phases of the lunar tides quiet magnetic days within a 27 day window has been used to remove the solar rotation effects relative residuals tec were calculated by performing a spectral analysis by removing the solar tide contributions lastly a lunar month size window was used to calculate the amplitude and phase of the lunar components lunar diurnal tide amplitudes showed a semiannual variation with maximum in the equinox months for almost all latitudes while lunar semidiurnal amplitudes were larger in december and january and may be related to sudden stratospheric warming events both components did not display significant longitudinal variation what could be due to the short range of longitude 30 degrees lunar diurnal amplitudes were basically uniform over brazil while lunar semidiurnal amplitudes showed some peaks over the equatorial ionization anomaly crest and minimum values near the magnetic equator

coupling between mesosphere and ionosphere over beijing through semidiurnal tides during the 2009 sudden stratospheric warming 1 sudden stratospheric warming ssw in the winter of 2008 2009 is the strongest recorded ssw event the enhancement in semidiurnal variation of ionospheric tec total electron content with phase shift forward is shown during 22 to 27 january 2009 based on the tec observations in beijing 40 30 n 116 19 e geographic 39 73 n dip latitude we focus on finding the reason for the tec variation winds observed by an all sky meteor radar in the same observatory are used to study mesospheric variation the semidiurnal solar tide in the mesosphere starts to increase before the ssw and maintains oscillation with period 16 20 days during the ssw the semidiurnal lunar tides in tec and wind start to increase on 17 and 15 january respectively although the semidiurnal lunar tide in tec over beijing almost dies out on 1 february that over equatorial ionospheric anomaly crest does not vanish until 15 february when lunar tide in wind tends to be very weak the maximum of lunar tide in wind appears on 2 february at 96 km with amplitudes of 15 m s and 21 m s for zonal and meridional winds the phase comparison shows that lunar tides in tec and zonal wind reach their maxima at almost the same time which is 2 4 h lag behind the meridional wind the coupling between the mesosphere and ionosphere contributes to the semidiurnal variation of tec through both solar and semidiurnal lunar tides the enhancement in semidiurnal lunar tide is responsible for the tec peak shift forward during the ssw

atmospheric tide 2 the solar and lunar semidiurnal components solar and lunar semidiurnal wind and temperature oscillations from the surface to 400 km are simulated for average solar activity conditions utilizing the numerical tidal model described in part 1 hough mode decomposition of the solstitial solar semidiurnal tide excited by h2o and o3 insolation absorption below 80 km indicates that it is characterized by a predominance of 2 2 below 60 km about equal contributions of 2 2 2 3 and 2 4 between 70 and 90 km mostly 2 4 with some 2 5 and 2 2 between 90 and 120 km and a predominance of 2 2 above 140 km with secondary contributions from 2 3 and 2 5 the solstitial lunar semidiurnal tide is characterized by a predominance of 2 2 below 70 km 2 4 with secondary contributions from 2 2 2 3 and 2 5 between 80 and 110 km and by 2 2 with a fairly strong secondary contribution from 2 3 above 120 km similar descriptions for both the solar and lunar oscillations apply at equinox except that the asymmetric 2 3 and 2 5 modes are absent relative to the solar component lunar temperature and wind amplitudes are sufficiently large 20 in the lower and upper thermosphere to account for some of the observed variability previously attributed to the solar tide amplitudes of the 2 4 and 2 5 modes above 100 km are significantly affected by mesospheric eddy diffusion coefficients in excess of 2 106 cm s 1 the total solar semidiurnal exospheric temperature oscillation for average solar conditions ranges from 10 20 k poleward of 40 n to 40 60 k equatorward of 30 n and has its origin in three sources of excitation all of comparable importance 1 euv solar radiation absorption in the lower thermosphere 100 200 km 2 in situ momentum coupling due to the interaction of diurnal winds and diurnally varying ion drag and 3 tides propagating upwards from below 100 km in addition the calculations are compared with rocket meteor radar partial reflection thomson scatter and satellite data to evaluate the consistency of the model with observations

simulating the lunar geomagnetic variations 1 the equivalent circuit method is used to simulate the lunar semidiurnal geomagnetic tides samples of observations of the lunar geomagnetic tide are also presented derived from analyses of hourly values of the horizontal component of the magnetic field recorded at several observatories these are compared to the results of the simulations at different seasons the winds used in the simulation are derived from the global scale wave model gswm and from those determined by forbes and gillette 1982 the calculations are only carried out for a lunar age of zero new moon but this still enables a comparison to be made with the observed phases of the lunar geomagnetic tide a mostly fair agreement is obtained both for the amplitude and phase of the lunar geomagnetic tide the agreement is generally better when winds from the global scale wave model are used rather than those from the earlier forbes and gillette model the july simulation gives poorer agreement there is corroborating evidence that the phase of the winds near the equator in july should be about 3 hours earlier than that presently given by the gswm the situation in december is different from other seasons both in the simulation and the observations but agreement is difficult to achieve on account of the year to year variability in this season

episodic deposition of illinois valley peoria silt in association with lake michigan lobe fluctuations during the last glacial maximum the chronology and cause of millennial depositional oscillations within last glacial loess of the central lowlands of the united states are uncertain here we present a new age model that indicates the peoria silt along the illinois river valley accumulated episodically from 28 500 to 16 000 cal yr bp as the lake michigan lobe margin fluctuated within northeastern illinois the age model indicates accelerated loess deposition coincident with regional glacial advances during the local last glacial maximum a weakly developed paleosol the jules geosol represents a period of significantly slower deposition from 23 700 to 22 000 cal yr bp a gastropod assemblage based reconstruction of mean july temperature shows temperatures 6 10 c cooler than modern during peoria silt deposition stable oxygen and carbon isotope values 18 o and 13 c of gastropod carbonate do not vary significantly across the pedostratigraphic boundary of the jules geosol suggesting slower loess accumulation was a result of reduced glacial sediment supply rather than direct climatic factors however a decrease in 18 o values occurred between 26 000 and 24 000 cal yr bp synchronous with the lake michigan lobe s southernmost advance this 18 o decrease suggests a coupling of regional summer hydroclimate and ice lobe position during the late glacial period

timing and origin for sand dunes in the green river lowland of illinois upper mississippi river valley usa abstract the recent increase in dune studies in north america has been heavily focused in the great plains while less attention has historically been given to the dune fields east of the mississippi river here we report ages and suggest a potential sediment source for sand dunes in the green river lowland illinois which may provide a better understanding of the dynamic interactions between eolian glacial lacustrine and fluvial processes that shaped the landscapes of the upper midwest seven coherent optically stimulated luminescence ages osl or optical ages obtained from four sites suggest that major dune construction in the green river lowland occurred within a narrow time window around 17 500 ago this implies either an enhanced aridity or an episodic increase of sediment supply at 17 500 years ago or combination of the both contrary to previous assertions that dune sand was sourced from the deflation of the underlying outwash sand deposited when the lake michigan lobe retreated from the area we propose that green river lowland dunes sand originated from the green bay lobe through the rock river specifically sediment supply increased in the rock river valley during drainage of glacial lake scuppernong which formed between 18 000 and 17 000 years ago when the green bay lobe retreated from its terminal moraine the lake drained catastrophically through the rock river valley providing glacial sediment and water to erode the preexisting sandy sediments throughout the remainder of the late pleistocene the laurentide ice sheet drained into larger more northerly glacial lakes that in turn drained through other river valleys therefore the dunes in the green river lowland formed only during the catastrophic drainage of glacial lake scuppernong but were stabilized through the remainder of the pleistocene this scenario explains the abrupt dune construction around 17 500 years ago and explains the lack of later dune activity up to the pleistocene holocene transition osl and radiocarbon ages also indicate that dunes were reactivated during the early middle and late holocene some eolian activation occurred within well defined dry intervals in the upper midwest suggesting that increased aridity may have been the primary driver in mobilizing sand however many ages do not correspond to drier periods in contrast to the relative coherency of the pleistocene osl ages from multiple study sites the holocene osl ages do not overlap from one site to another suggesting that increased aridity alone cannot explain the multiple phases of dune reactivation in the holocene therefore we conclude that the combined effect of localized disturbances and greater aridity acted in concert to increase eolian sand activity in the holocene the multiple periods of eolian activity during the holocene suggest a high potential for future sand activation in the region and these results are informative for environmental prediction and potential future mitigation

high resolution proxy record of holocene climate from a loess section in southwestern nebraska usa abstract multi proxy analysis was used to produce a high resolution paleoclimatic record from an exceptionally thick section of the holocene bignell loess near wauneta southwestern nebraska in the central great plains the wauneta section has excellent age control based on optically stimulated luminescence osl and radiocarbon dating and records multiple episodes of rapid loess deposition alternating with slower deposition and soil formation the lowermost and uppermost osl ages obtained from the bignell loess are 10 250 610 years 5 9 m depth and 100 10 years 0 1 m depth respectively as a result the holocene has been temporally confined stratigraphically the bignell loess overlies the late pleistocene peoria loess deposited 21 14 ka and the two units are separated by the brady soil which is distinguished by its color and other pedogenic features l a b color parameters and organic carbon content of bignell loess are sensitive proxies to differentiate drought induced aeolian sediment layers from the intercalated soil horizons soil organic carbon derived 13 c data suggest that the c 3 dominated floral environment during peoria loess deposition shifted dramatically to a c 4 dominated environment during brady soil formation in response to a warming trend even greater c 4 abundance characterized the late holocene high resolution 13 c data support the contention that c 3 vs c 4 vegetation change in the holocene reflects ecosystem response to frequent vegetation disturbance under arid conditions time series analysis reveals that 13 c and color parameters display high frequency variation with periodicities of 103 118 years and 103 years respectively similar periodicities were also reported in studies of north dakota lakes though the physical mechanism responsible is uncertain comparison of bignell loess color and tropical pacific sea surface temperatures ssts allows evaluation of a proposed teleconnection between drought in the great plains and la nina like conditions in the tropical pacific the loess color index and eastern tropical pacific sst display broad similarities through the late pleistocene and holocene that are consistent with this teleconnection on the other hand drought centered at 3800 years ago is not consistent with the teleconnection and the end of early holocene aridity at the wauneta section around 6500 years ago is much earlier than the corresponding rise in sst and increase in el nino frequency in the eastern tropical pacific

revised global model of thermosphere winds using satellite and ground based observations thermospheric wind data obtained from the atmosphere explorer e and dynamics explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground based incoherent scatter radar and fabry perot optical interferometers to generate a revision hwm90 of the hwm87 empirical model and extend its applicability to 100 km comparison of the various data sets with the aid of the model shows in general remarkable agreement particularly at mid and low latitudes the ground based data allow modeling of seasonal diurnal variations which are most distinct at mid latitudes while solar activity variations are now included they are found to be small and not always very clearly delineated by the current data they are most obvious at the higher latitudes the model describes the transition from predominately diurnal variations in the upper thermosphere to semidiurnal variations in the lower thermosphere and a transition from summer to winter flow above 140 km to winter to summer flow below significant altitude gradients in the wind are found to extend to 300 km at some local times and pose complications for interpretation of fabry perot observations

tectonics sedimentation and surface processes from the erosional engine to basin deposition this special issue collects a number of papers mainly reflecting discussions during the tectonics sedimentation and surface processes sessions tssp organized at recent egu conferences 2012 2013 2014 as well as related studies that have appeared in earth surface processes and landforms over the last two years the sedimentary record has long been used to invert for deformation at all scales and in all tectonics settings growth strata sediment provenance sequence stratigraphy and changing depositional environments have all provided first order constraints on quantifying deformation at a range of spatial and temporal scales at the same time these studies have motivated much work on the influence of tectonics on both sedimentation patterns and basin fill successions however relatively few studies have considered the whole integrated system of catchment erosion fluvial transport and sediment deposition together often concentrating on either the basin or the catchment separately recently however methodological progress in quantifying rates of surface processes in the upstream erosion and transfer zones as well as revived interest in the couplings between surface processes tectonics and climate have made it possible to renew our understanding of the interactions between sedimentation and tectonics within the framework of the whole integrated sediment routing system although the studies within this special issue are only a fraction of the work presented over the last five years of the tssp sessions the manuscripts presented here reflect a selection of the broad content and diversity of studies that integrate both sedimentation and surface processes to understand deformation in the context of sedimentary systems they highlight and are organized into three active challenges of the field 1 tectonics and climate into landscapes 2 signal propagation within sediment routing systems and 3 modeling of tectonic and surface processes

evidence for bioturbation of luminescence signals in eolian sand on upland ridgetops southeastern minnesota usa abstract this study sought to identify the age of eolian sand on narrow ridges in the root river valley of southeastern minnesota the ridges in the region are cored by ordovician dolomite and cambrian sandstone but the ridge tops are typically covered with late wisconsin peoria and older loess units in some locations peoria loess is absent and the ridgetops are covered with up to 3 m of eolian sand that was likely sourced from local river valleys and transported to the uplands by sand ramps we studied nine ridgetop soil profiles and collected seventeen osl samples from eolian sand at depths ranging from 0 3 to 2 6 m below the present ground surface all osl samples were analysed using small aliquots where 90 150 m quartz grains were applied to the inner 2 mm of 10 mm aluminum disks the osl ages ranged from 12 3 to 1 5 ka indicating a significant amount of age variability and potentially suggesting nearly continual eolian deposition throughout the holocene however several key differences were identified between those samples taken from within 1 m of the ground surface compared with samples that were more deeply buried those samples collected from depths of greater than 1 m yielded ages that were tightly clustered between 12 3 and 10 3 ka while samples taken from depths of less than 1 m showed ages with much higher spread that ranged from 1 5 to 10 1 ka the samples collected from within 1 m of the present ground surface also commonly showed higher spread in their equivalent dose distributions and higher overdispersion values relative to the samples that were more deeply buried this suggests the luminescence signals from the upper portions of these deposits were reset after burial most likely by bioturbation and that the osl ages are not depositional ages this interpretation is supported by evidence from a core sample collected from one of our sites that shows primary eolian lamina are preserved below 1 4 m depth but not above this depth presumably the bioturbation agents were effective at both resetting the luminescence signal and disturbing the primary bedding to depths of at least 1 m if bioturbation occurred below this threshold it apparently did not impact either of these indicators our findings suggest the upper 1 m of these profiles were impacted by bioturbation and that all of the eolian sand on these ridgetops was likely deposited prior to 10 1 ka

lunar tides in the mesosphere over christmas island 2 n 203 e this paper reports the first measurement of the lunar tide in upper atmosphere winds at an equatorial site wind velocities have been measured at christmas island in the pacific ocean from 1990 to 1993 over the height range 82 to 98 km and hourly values have been used to deduce the lunar tide using a least squares method amplitudes are 1 to 3 m s with only small changes in phase with season a large phase change over the early part of 1990 was found in the northward wind generally the phase difference between northward and eastward winds was about 6 hours and good agreement was obtained with a tidal model developed from that of forbes 1982a

transient salt transport modeling of shallow brine beneath a freshwater lake the sea of galilee israel during a lake highstand phase in the late pleistocene the former saline lake lisan covered the topographic depression of kinarot basin currently occupied by the freshwater lake sea of galilee it was hypothesized that during this period the dense saline waters of lake lisan percolated into the sediment the recession of the saline lake from the basin and the rapid formation of a freshwater lake triggered solute transport from the sediment into the lake a one dimensional numerical model of solute transport that considers sediment compaction was developed to simulate chloride transport from the sediment into the lake simulation results were compared with measured chloride concentration profiles in sediment cores on the basis of a sensitivity analysis results are in agreement with the hypothesis that lake lisan solutes are currently discharged into the sea of galilee the calculated upward water velocity in the sediment ranges between 9

measuring groundwater transport through lake sediments by advection and diffusion a method for estimating low rates of groundwater inflow and outflow through the bottom sediments of surface waters was developed and tested a one dimensional advection diffusion model was fitted to measured pore water profiles of two nonreactive solutes tritiated water and chloride and the advection rate was calculated by a nonlinear least squares technique using 3h profiles measured 0 0 5 m below the sediment water interface rates of groundwater advection into a lake through interbedded sands and gyttja were estimated to be about 1 0 m year in midlake locations underlain by soft organic gyttja rates of advection were much lower 0 1 m year knowledge of the rate and direction of groundwater flow substantially altered the interpretation of pore water profiles within the sediments and the fluxes of solutes this technique can be used to estimate flow rates less than 2 m annum with minimal disturbance without enclosing the sediments in a container in a diversity of systems