database of friction angles of sand and consolidation characteristics of sand silt and clay abstractthe paper presents diagrams of the 1 drained and undrained effective stress friction angles of sand 2 dilatancy angle of sand 3 parameters in a nonlinear constrained modulus expression for virgin loading unloading and reloading on sand and silt and 4 diagrams with the coefficient of permeability for sand silt and clay the database parameters are suitable for preliminary assessments or applications when assumed parameters are acceptable the database can also be helpful in planning and interpreting site specific tests and in reducing the number of site specific tests for important projects the parameters should be determined by site specific tests

thermospheric zonal mean winds and tides revealed by champ we present direct global observations of longitudinally averaged champ zonal winds gathered between 2003 and 2007 a diurnal variation dominates the global zonal wind westward flows are observed from the early morning through afternoon hours while eastward flows peak in the evening a semidiurnal harmonic is also present with magnitudes that are approximately one third of the diurnal harmonic the time mean wind indicates westward winds over much of the globe with weak superrotation e or eastward winds that is symmetric about the equator during equinox and confined to the winter hemisphere at solstice diurnal and time mean champ winds agree fairly well with the whole atmosphere model some differences are observed in the semidiurnal and higher order tidal winds that underscore the challenges of modeling the sources sinks and mean wind effects upon tides between the surface and 400 km

altitude variations of the horizontal thermospheric winds during geomagnetic storms 1 it is generally assumed that viscosity smooths out vertical gradients of the horizontal thermospheric winds in the upper thermosphere and thus observations of neutral winds at one height can be used at other altitudes in this region in this paper we present neutral wind simulations of the may 1997 geomagnetic storm using the coupled magnetosphere ionosphere thermosphere cmit model the model results show that during quiet periods the assumption of a shearless vertical profile of the horizontal winds is generally valid in low and middle latitudes although vertical shears do occur in wind profiles in the upper thermosphere in some locations at higher latitudes during disturbed periods large variations in the vertical profiles of the upper thermospheric winds are seen globally in the model simulations a diagnostic analysis of the forcing processes in the neutral momentum equations shows that 1 during quiet time there are shearing forces most noticeably the pressure gradient and ion drag in the upper thermosphere that result in a net momentum forcing that changes with height this induces altitude variations in the wind profiles at high latitudes and sometime even at middle latitudes 2 during storm time momentum advection which is relatively weak during the quiet time becomes a dominant force globally pressure gradient forces are also significantly enhanced ion drag on the other hand can be enhanced or suppressed depending on the location of positive or negative effects all these forces exhibit significant altitude variations that lead to a net force that is greatly enhanced and has large vertical shears this produces globally enhanced neutral winds that vary with height 3 viscosity is less important than other forcing processes during both the quiet and storm periods and thus cannot prevent shears from occurring in the vertical profiles of the horizontal winds viscosity has an insignificant effect on vertical shears that change with height linearly it however does restrict vertical shears that vary nonlinearly with height the effectiveness of the viscosity in restricting such shears depends on its magnitude in our simulations viscosity is weaker than other forcing processes and thus is a relatively slow process so it will take a few hours for viscosity to reduce such shears

angles of friction and dilatancy of sand it is generally realized that the peakfriction angel depends not only on density but alsoon the stress path including differences betweenplane strain and triaxial testing conditions indeed plane strain and triaxial strain angles can differ bymore than 58 for a dense sand for a loose sand atthe critical density it is often suggested that similardifferences occur e g stroud 1971 lade 1984 however some authors have presented data thatsuggest a unique critical state angle e g rowe 1962 1971 bolton 1986 this technical note presents data on a uniquecritical state angle the implication is that thefailure criterion of a very loose sand is accuratelydescribed by the mohr coulomb condition whichgives the known six sided pyramid in principalstress space the test data on dense as well as loose hostunsand are also used to study the rate of dilation this topic was extensively treated by bolton 1986 and it is now generally accepted that thetriaxial rate of dilation coincides with the rate ofdilation found in plane strain tests followingroscoe 1970 bolton used an angle of dilatancyl

first observations of simultaneous interhemispheric conjugate high latitude thermospheric winds 1 we report the first observations of simultaneous high latitude interhemispheric f region neutral wind fields by combining the 630 nm optical measurements from two scanning doppler imagers sdis and three fabry perot interferometers fpis for a period exceeding 5 h from the southern hemisphere a sdi at mawson and a fpi at davis both in antarctica are geomagnetically mapped onto the northern hemisphere these data are combined in the northern hemisphere with a sdi at longyearbyen svalbard and two fpis near kiruna in sweden and sodankyla in finland geomagnetic conditions were moderate kp 3 3 and steady although the interplanetary magnetic field bz component did change polarity several times there is good agreement between the conjugate 630 nm optical intensities and wind vectors where the two sdis fields of view overlap all wind field vectors are overlaid onto the northern super dual auroral radar network ion convection contours qualitatively the agreement between neutral and ion flow is remarkably good throughout the study interval even down to mesoscale spatial size

effect of sleeves and skirts on mitigating spudcan punch through in sand overlying normally consolidated clay punch through failure of mobile jack up rigs is still a main concern for spudcan foundations using centrifuge model tests and numerical modelling this paper examines the mitigating effect of top

formation processes at sites with high resolution sequences in the crimean middle paleolithic the kabazi v rock shelter and the open air site of kabazi ii compared abstract several paleolithic sites in the crimea are characterized by long stratigraphic sequences with numerous thin in situ archaeological horizons in this case study we compare two neighboring sites at kabazi mountain parts of whose sequences are contemporaneous for similarities and differences in their site formation processes during ois 3 at kabazi ii 15 m of mainly colluvial sediments accumulated behind a huge limestone block differences in the dynamics of the colluvial sedimentation led to archaeological horizons preserved in situ and assemblages moving downslope into the excavation area periods of stability due to vegetation cover upslope made soil formation processes possible kabazi v is a buried rock shelter with a different sedimentological setting here sediments were built up by the dissolution of soft nummulitic limestone and influenced by running water and are in part sandwiched between massive rock fall despite the differences in site type the deposits of both sites are characterized by autochthonous inside and allochthonous outside deposits in both cases the preservation of deposits is due to their protection by large rock fall mean annual sedimentation rates show that the archaeological resolution of the sequences is more a consequence of recurrent human use over long periods than of high absolute sedimentation rates the average time elapsing in each case between the archaeological layers indicates that the base camp of kabazi v was more frequently used by neanderthals than the kill and butchering site of kabazi ii this suggests long term persistence of the site catchment criteria applied at kabazi mountain and an important role for base camps in the crimean middle paleolithic perception of landscape

an empirical model of the earth s horizontal wind fields hwm07 1 the new horizontal wind model hwm07 provides a statistical representation of the horizontal wind fields of the earth s atmosphere from the ground to the exosphere 0 500 km it represents over 50 years of satellite rocket and ground based wind measurements via a compact fortran 90 subroutine the computer model is a function of geographic location altitude day of the year solar local time and geomagnetic activity it includes representations of the zonal mean circulation stationary planetary waves migrating tides and the seasonal modulation thereof hwm07 is composed of two components a quiet time component for the background state described in this paper and a geomagnetic storm time component dwm07 described in a companion paper

predicting the resistance profile of a spudcan penetrating sand overlying clay assessment of the risk of punch through failure of spudcan foundations on sand overlying clay requires prediction of the full penetration resistance profile from touchdown and through punch through to equilibrium of the vertical resistance at depth in the underlying clay layer this study uses the coupled eulerian lagrangian approach a large deformation finite element analysis method to model the complete penetration resistance profile of a spudcan on sand overlying clay the sand is modeled using the mohr coulomb model while the clay is modeled using a modified tresca model to account for strain softening the numerical method is then used to simulate a series of spudcan penetration tests performed in a geotechnical centrifuge on medium dense sand overlying clay the punch through behavior observed in the experiments is replicated and the penetration resistance profiles from numerical analyses are generally a reasonable match to the experimental measure ments the influences of the sand layer height to foundation diameter ratio sand clay interface shear strength and strength gradient in clay on the penetration resistance profiles are explored in a complementary parametric study the penetration resistance in the underlying clay layer is well predicted using a simple linear expression for the bearing capacity factor for the spudcan and underlying sand plug this expression is combined with an existing failure stress dependent model for predicting peak resistance to form a simplified method for prediction of the full penetration resistance profile this new method provides estimates of the vertical penetration that the spudcan will run during the punch through event it is validated against both medium dense and dense sand centrifuge tests

frontal advance of turf banked solifluction lobes kluane range yukon territory canada humus horizons associated with thirteen solifluction lobes on a single slope were radiocarbon dated at fixed distances behind the risers as well as ahead of the lobes the dated horizons together with stratigraphic observations of planar discontinuities inside the lobes and shallow burial of vegetation ahead of the lobes all suggest rapid advance of lobe fronts we infer that lobe advance at this site results from slow accumulation of soliflucted material behind a relatively rigid riser progressive steepening of the riser and build up of stress and finally rupture of the front and its collapse onto the slope rebuilding of the lobe usually then takes place the time for a full cycle of development is estimated to be in the order of a few hundred years long term frontal movement appears inversely related to lobe size and is mainly controlled by soil moisture and sediment characteristics these findings call into question the usefulness of solifluction lobe advance rates for paleoclimate reconstructions at least at this site

first palmer and millstone hill midlatitude conjugate observation of thermospheric winds the first midlatitude conjugate thermospheric wind observations in the american sector showed various degrees of conjugacy between palmer 64 s 64 w magnetic latitude mlat 50 s and millstone hill 42 82 n 71 5 w mlat 53 n under three different geomagnetic conditions recovery after a substorm moderately active and quiet the agreement with the national center for atmospheric research s thermosphere ionosphere electrodynamics general circulation model tiegcm simulations also varies with the geomagnetic activity level during substorm recovery the observations at palmer pa and millstone hill mh both showed strong westward zonal winds which the standard tiegcm greatly underestimated inadequate ion convection pattern size and lack of effect from subauroral polarization streams saps may be the cause of the large discrepancy the tiegcm with a saps model produced stronger westward zonal winds near pa but did not change the zonal wind near mh the empirical saps model needs further refinements in general there is better conjugacy with moderate geomagnetic activity levels the tiegcm also agrees better with the observations under geomagnetically quiet conditions the meridional winds appear to be less conjugate the agreement between the observations and model is reasonable optical conjugate observations are severely limited by the seasons and weather conditions in the two hemispheres yet they are necessary to understanding the thermospheric dynamics in the subauroral region and its relationship with geomagnetic activity levels the comparisons with tiegcm are necessary for future model improvements

thermosphere density response to the 20 21 november 2003 solar and geomagnetic storm from champ and grace accelerometer data 1 densities in the 400 500 km height region inferred from accelerometer measurements on the champ and grace satellites are utilized to study the response to the isolated and severe geomagnetic storm of 20 21 november 2003 the champ and grace satellites provide data at approximate local times of 1110 2310 and 1430 0230 hours respectively in a global sense density increases of order 300 800 occur during this storm with relatively little time delay at high latitudes and with about 4 hour delay at the equator significant latitudinal asymmetries in the response are discussed in the context of neutral wind patterns and enhanced summer versus winter joule heating rates at high latitudes comparisons with the nrlmsise 00 empirical model densities during this period show marked differences in amplitude of the response as well as latitudinal and temporal structures evidence for a tight coupling between solar wind and neutral density variability is found for the high latitude summer hemisphere near noon in that densities near 410 km are very responsive to increases in solar wind dynamic pressure even during periods when both bz and by are near zero or positive filtering of the data reveals regional scale 1000 2000 km density anomalies that are common between the champ and grace measurements during the geomagnetic disturbance alternating regions of density enhancements 50 and depressions 50 exist between the pole and low to middle latitudes that have the appearance of a standing wave pattern during magnetically quiet intervals before and after the storm daytime density depressions 4 8 are seen that track the magnetic equator while density enhancements 10 track the latitudes of the ionospheric appleton anomaly peaks large scale 1000 km wave like structures are also prevalent during both day and night during the magnetic disturbance and extend throughout both hemispheres consistent with the concept that these are associated with the so called direct gravity waves forced in the auroral regions and propagating far from the source substantial variability is also present at medium scales 300 500 km but these structures are confined mainly to middle to high latitudes in accord with theoretical expectations grace a and grace b data are used in a feasibility study of the detection of small scale wave activity by taking advantage of the 30 s separation of the satellites in the same orbital plane despite the large amount of maneuvers which are not always recorded this first analysis is promising amplitude variations of order 10 20 and wave speeds of 1000 1500 m s 1 are observed

solifluction and related processes eastern banks island n w t mean surface soil movement measured over the period 1972 1983 on eight relatively low angle 10 well drained slopes on eastern banks island averaged 0 6 cm year substantial variation in mean movement was recorded amongst the slopes the variation relates to differences in soil moisture conditions soil grain size and the position of the measurement transect relative to the crest or base of the slope the former two variables and therefore the rate of movement can change rapidly across any given slope particularly when stripes are present three types of movement are identified in the study area 1 mud burst and mud flow 2 classic solifluction and 3 pluglike flow the latter occurs along discrete shear planes located both within and at the base of the active layer the existence of episodic and relatively rapid mass movement on these slopes suggests that long term monitoring programs are necessary to adequately assess and measure slope movement

linking debris flow hazard assessments with geomorphology debris flow hazard assessment schemes are commonly based on empirical physical or numerical methods and techniques inherent in all methods is generally the assumption of unlimited sediment supply this study compares model inputs of sediment requirements for debris flows with estimated sediment reproduction from both solifluction and rockwall retreat the analysis is carried out in bildudalur a community in the westfjords of iceland geomorphic techniques are applied to determine the set of natural processes acting in this landscape to estimate spatial distribution of relevant processes to approximate level of processes activity and to provide information for scenario modeling debris flow volumes are determined by coupling rainfall magnitudes and catchment sizes with average sediment contents rockwall retreat and solifluction rates are based on literature reviews for a rainstorm with a 10 year return period debris flow volumes are calculated for 12 different creeks rates are assumed for solifluction with a velocity of 0 25 m yr at an average depth of 0 5 m and for rockwall retreat with 2 mm yr comparing sediment requirements with estimated sediment reproduction leads to a factor of deficit ranging between 6 2 and 8 5 thus the sediment storage is not refilled as fast as the next potential triggering rainfall occurs consequently if a debris flow has occurred in the past all sediment is removed and the following rainstorm event is djustt causing a flood which is by far less destructive than a debris flow event the challenge of future debris flow hazard assessment schemes is to include geomorphic analysis to be able to obtain more sustainable results d 2004 elsevier b v all rights reserved

pingo collapse and paleoclimatic reconstruction long term field studies of contemporary pingo growth collapse and rampart formation along the western arctic coast of canada provide criteria that may be helpful in the identification of pingo ramparts in nonpermafrost environments such criteria include the volume of the ramparts which should approximate that of the enclosed depressions from which the rampart materials were derived peripheral deposits associated with mass wasting streamflow and debris flow casts of dilation crack ice trending across the ramparts and high angle peripheral normal faults the conventional method of correlating the present mean annual air temperature with the present pingo distribution to establish warm side limiting temperatures for paleoclimatic reconstruction is unsound because most pingos in north america and the soviet union commenced growth hundreds to thousands of years ago under mean annual air temperatures that may have differed greatly from those of the present some other factors to be considered in paleo

average characteristics and activity dependence of the subauroral polarization stream 1 data from the millstone hill incoherent scatter radar taken over two solar cycles 1979 2000 are examined to determine the average characteristics of the disturbance convection electric field in the midlatitude ionosphere radar azimuth scans provide a regular database of ionospheric plasma convection observations spanning auroral and subauroral latitudes and these scans have been examined for all local times and activity conditions we examine the occurrence and characteristics of a persistent secondary westward convection peak which lies equatorward of the auroral two cell convection individual scans and average patterns of plasma flow identify and characterize this latitudinally broad and persistent subauroral polarization stream saps which spans the nightside from dusk to the early morning sector for all kp greater than 4 premidnight the saps westward convection lies equatorward of l 4 60 invariant latitude spans 3 5 of latitude and has an average peak amplitude of 900 m s in the predawn sector saps is seen as a region of antisunward convection equatorward of l 3 55 spanning 3 of latitude with an average peak amplitude of 400 m s

first u s china joint ground based fabry perot interferometer observations of longitudinal variations in the thermospheric winds for the first time three fabry perot interferometers from the u s boulder 40 degrees n 105 degrees w 49 degrees n magnetic latitude mlat and china xinglong 40 degrees n 115 degrees e 34 degrees n mlat kelan 39 degrees n 112 degrees e 33 degrees n mlat were used to examine the longitudinal variations in the thermospheric winds due to the geomagnetic latitude differences between the american and asian sectors during a case of quiet geomagnetic condition the meridional winds were very similar at the u s and chinese stations the meridional winds at boulder reached most equatorward winds after midnight whereas in china the largest equatorward winds were found near midnight the boulder zonal winds turned westward earlier in the morning hours and had larger diurnal variations because of its higher magnetic latitude during the case of low geomagnetic activity kp similar to 2 the meridional winds were still similar in the u s and in china boulder zonal winds had much larger diurnal variation compared to the quiet condition kp similar to 1 thermosphere ionosphere electrodynamics general circulation model simulations show a very good agreement with observation for the meridional winds the simulated zonal winds exhibit noticeable differences with observations but the general tendencies in longitudinal variations with a larger diurnal variation near the auroral oval are correct simulations showed that the ion drift is not directly responsible for the longitudinal variations in the winds the pressure gradient had more direct effect on the longitudinal changes in the winds the simulation results also showed larger diurnal variations at higher geomagnetic latitudes due to the auroral oval heating nonmigrating tides were not observed in the two cases in october 2012

centrifuge model study of spudcan penetration in sand overlying clay a series of centrifuge model tests has been conducted to investigate the bearing resistance of spudcan foundations of offshore jack up rigs in sand overlying normally consolidated clay the spudcan bearing resistance profiles measured in most of the tests recorded a peak resistance at a shallow depth within the upper sand layer followed by an abrupt post peak reduction in resistance causing the spudcan to plunge into the underlying soft clay this phenomenon is commonly termed as spudcan punch through hazard which potentially leads to severe structural damage of jack up rigs in the field the centrifuge test results revealed that the ratio of upper sand layer thickness over spudcan diameter and the ratio of bearing resistance between the upper sand and underlying clay affect the development of spudcan bearing resistance the limitations of existing design methods which were derived for the ultimate bearing capacity of pre embedded shallow foundation to assess the spudcan bearing resistance depth prof

the development of near surface ground ice during the holocene at sites near mayo yukon territory canada an examination of soil thermal and hydrologic regimes at several sites near mayo yukon territory and the ground ice stratigraphy of a thaw slump headwall close to these sites supports the hypothesis that an ice rich zone frequently observed at the base of the active layer may be due to the annual water balance of permafrost observations demonstrate that ice lenses have grown at the top of permafrost in soil tubes installed in 1983 in addition 90 cm of segregated ice are exposed in the thaw slump headwall above a thaw unconformity dated at 8870 200 years bp but below the base of the present active layer these data suggest that the rate of water incorporation into permafrost over the last 8000 years in the mayo area has been at least 0 1 mm yr 1

revealing the bearing capacity mechanisms of a penetrating spudcan through sand overlying clay the safe and economic use of mobile jack up structures is still hindered by limited understanding of the installation of their large conical spudcan footings in layered sand over clay sites this paper addresses this by detailing experimentally observed bearing failure modes induced during the penetration of a spudcan through a layer of sand into underlying normally consolidated clay digital images were captured continuously by installing a half spudcan against a transparent window and analysed using a particle image velocimetry technique coupled with close range photogrammetry correction as the experiments were performed in a geotechnical centrifuge the observed mechanisms occurred in stress conditions of similar magnitude to the offshore case the experimental evidence provides a failure modes at different spudcan penetration depths b the transitional failure mechanism at the event of peak bearing resistance and c the changes in overall failure mechanism due to varying geometric and streng

assessing the punch through hazard of a spudcan on sand overlying clay a complete analytical method to describe the full load penetration resistance profile of a mobile jack up spudcan footing penetrating a sand over clay stratigraphy is described it is based on both large deformation finite element analyses and geotechnical centrifuge experiments the coupled eulerian lagrangian cel approach is used to accommodate the large deformations of a spudcan footing penetrating sand overlying clay modified mohr coulomb and tresca models describe the sand and clay behaviour with modifications accounting for the effects of strain softening on the response of the soil the cel results are shown to match centrifuge tests well allowing the numerical study to be extended parametrically and with confidence to cover the range of layer geometries sand relative densities and footing shapes that are of practical interest to offshore jack ups the results are used to a assess the performance of an existing model to predict the peak resistance in the sand layer extending its range of

climatologies of nighttime upper thermospheric winds measured by ground based fabry perot interferometers during geomagnetically quiet conditions 1 local time latitudinal seasonal and solar cycle dependence 1 we analyze ground based fabry perot interferometer observations of upper thermospheric 250 km horizontal neutral winds derived from doppler shifts in the 630 0 nm red line nightglow the winds were measured over the following locations south pole 90 s halley 76 s 27 w arequipa 17 s 72 w arecibo 18 n 67 w millstone hill 43 n 72 w sondre stromfjord 67 n 51 w and thule 77 n 68 w we derive climatological quiet time kp 150 the seasonal dependence of the winds is generally annual but there are isolated cases in which a semiannual variation is observed within the austral winter winds measured from the south pole show a substantial intraseasonal variation only along longitudes directed toward the magnetic pole imf effects are described in a companion paper

dwm07 global empirical model of upper thermospheric storm induced disturbance winds 1 we present a global empirical disturbance wind model dwm07 that represents average geospace storm induced perturbations of upper thermospheric 200 600 km altitude neutral winds dwm07 depends on the following three parameters magnetic latitude magnetic local time and the 3 h kp geomagnetic activity index the latitude and local time dependences are represented by vector spherical harmonic functions up to degree 10 in latitude and order 3 in local time and the kp dependence is represented by quadratic b splines dwm07 is the storm time thermospheric component of the new horizontal wind model hwm07 which is described in a companion paper dwm07 is based on data from the wind imaging interferometer on board the upper atmosphere research satellite the wind and temperature spectrometer on board dynamics explorer 2 and seven ground based fabry perot interferometers the perturbation winds derived from the three data sets are in good mutual agreement under most conditions and the model captures most of the climatological variations evident in the data

solifluction rates processes and landforms a global review abstract field data on the rates of solifluction and associated parameters are compiled from the literature in an attempt to evaluate factors controlling the spatial variability in solifluction processes and landforms with special attention on the climate solifluction relationship the analyzed data originate from 46 sites over a wide range of periglacial environments from antarctic nunataks to tropical high mountains solifluction broadly defined as slow mass wasting resulting from freeze thaw action in fine textured soils involves several components needle ice creep and diurnal frost creep originating from diurnal freeze thaw action annual frost creep gelifluction and plug like flow originating from annual freeze thaw action and retrograde movement caused by soil cohesion the depth and thickness of ice lenses and freeze thaw frequency are the major controls on the spatial variation in solifluction processes near the warm margin of the solifluction affected environment diurnal freeze thaw action induces shallow but relatively rapid movement of a superficial layer 5 10 cm thick on average often creating the thin stone banked lobes typically seen on tropical high mountains in addition to diurnal movement annual frost creep and gelifluction may occur on slopes with soil climates of seasonal frost to warm permafrost dislocating a soil layer shallower than 60 cm at a rate of centimeters per year and eventually producing medium size solifluction lobes in high arctic cold permafrost regions two sided freezing can induce plug like flow of a soil mass 60 cm or thicker the correlation between process and landform suggests that the riser height of lobes is indicative of the maximum depth of movement and prevailing freeze thaw type climate change may result in new different ground freezing conditions thereby influencing the surface velocity and maximum depth of soil movement soil moisture and topography also control solifluction high moisture availability in the seasonal freezing period enhances diurnal freeze thaw action and subsequent seasonal frost heaving the latter contributes to raising the moisture content of the thawed layer and promotes gelifluction during the thawing period the slope angle defines the upper limit of the surface velocity of solifluction a diagram correlating the potential frost creep with the actual surface velocity permits an inter site comparison of the relative magnitude of solifluction components physically based modelling of periglacial slope evolution requires synthetic and more detailed field monitoring and laboratory simulations of solifluction processes

short term variability in the dates of the indian monsoon onset and retreat on the southern and northern slopes of the central himalayas as determined by precipitation stable isotopes this project launched the first study to compare the stable isotopes 18o and d in daily precipitation at kathmandu located on the southern slope of the central himalayas and tingri located on the northern slope the results show that low 18o and d values of summer precipitation at the two stations were closely related to intense convection of the indian monsoon however summer 18o and d values at tingri were lower than those at kathmandu a result of the lift effect of the himalayas coupled with convection disturbances and lower temperatures at tingri in winter the relatively high 18o and d values at the two stations appears to have resulted from the influence of the westerlies compared with those during the summer the subsidence of the westerlies and northerly winds resulted in relatively high 18o and d values of the winter precipitation at tingri winter 18o and d values at kathmandu far exceeded those at tingri due to more intense advection of the southern branch of the westerlies and higher temperatures and relative humidity at kathmandu the detailed differences in stable isotopes between the two stations follow short term variability in the onset date of the indian monsoon and its retreat across the central himalayas during the sampling period the indian monsoon onset at tingri occurred approximately 1 week later than that at kathmandu however the retreat at tingri began roughly 3 days earlier clearly the duration of the indian monsoon effects last longer at kathmandu than that at tingri our findings also indicate that the india monsoon travels slowly northward across the central himalayas due to the blocking of the himalayas but retreats quickly

up in the refrigerator geomorphic response to periglacial environments in the upper mississippi river basin usa abstract james c knox was best known for his work on holocene and historical changes in fluvial systems but he also had a long standing interest in the effects of late pleistocene periglacial environments on landscape evolution in parts of the upper mississippi river basin that were just outside the laurentide ice sheet margin or as knox put it up in the refrigerator knox and others in the quaternary community of the midwestern u s often suggested that hillslope erosion was accelerated under periglacial conditions so that glacial periods have had a dominant effect on the landscape we see today this paper reviews the evidence and reasoning supporting that view in a study area of the upper mississippi basin bordered on three sides by ice margins of the last glaciation including the wisconsin driftless area and adjacent landscapes sparse but compelling paleoecological data and relict ice or sand wedge polygons provide clear evidence for a cold climate and widespread permafrost around the peak of the last glaciation in highly dissected relatively high relief parts of the study area the loess and soil stratigraphy on ridgetops and the colluvial mantles on steeper slopes are best explained by highly effective hillslope erosion including solifluction during and just after the last glacial maximum knox used the post depositional truncation of a loess unit to quantify contrasting late pleistocene and holocene sediment yields from a small driftless area watershed while the late pleistocene yield indicates accelerated erosion it is still lower than modern sediment yields in many tectonically active or semiarid landscapes and it may reflect deposition of highly erodible loess as well as effects of periglacial conditions the views of knox and other midwestern geomorphologists on landscape evolution through glacial interglacial cycles were highly influenced by the work of robert v ruhe ruhe proposed that an episode of widespread erosion during and just after the last glacial maximum can explain enigmatic aspects of quaternary stratigraphy and the soil landscape on the iowan erosion surface a very low relief landscape of the study area ruhe s key evidence is still valid though it needs to be separated from an implausible model of landscape evolution interpretation of the iowan erosion surface and other low relief landscapes just outside the ice margin also requires recognition of the profound effect of eolian processes on those landscapes under periglacial conditions many new insights on landscape evolution in the study area could result from wider application of cosmogenic nuclide based methods to assess glacial interglacial changes in basinwide rates of erosion and residence time of soils just as important a need exists for much more field based characterization of hillslope fluvial and eolian sediments for comparison with those of modern permafrost regions and past periglacial environments in europe

deformation induced microstructures in soils affected by mass movements the soil deformation produced by mass movements gives rise to specific microscopic features the study of some markers of deformation such as the orientation of rigid clasts and the morphology of fine grained intercalations indicates that in most cases mass movements can be related to simple shear the development of these features varies according mainly to the type of mass movement solifluction debris flow or earth slide different factors play a significant role in their formation intrinsic soil characteristics such as the grain size of the matrix water content and matrix element viscosity ratios and external factors such as the intensity and homogeneity of deformation a careful study of the microscopic features leads to a better understanding of the dynamics of mass deposits

comparison of the neutral wind seasonal variation from midlatitude conjugate observations the seasonal variation of f region neutral wind from the midlatitude conjugate fabry perot interferometer observations has been studied the meridional wind at palmer station 64 s 64 w has a significant local time dependence with strong equatorward wind at midnight and polarward wind at dawn and dusk the zonal wind switches from eastward to westward in the early morning section from the june solstice austral winter to equinox the maximum meridional wind increases from 90 m s to 130 m s and the zonal wind switches direction at an earlier local time the neutral winds from palmer have been compared with those from the geomagnetic conjugate location millstone hill mh at equinox the local time variation of neutral wind shows a very good conjugacy between these two locations but at june solstice the similarity in the zonal wind becomes less clear this seasonal dependence can be attributed to the seasonal variation of solar and geomagnetic forcings the annual variation of daily average neutral wind from palmer and mh has also been compared the meridional wind shows a clear offset of season and the magnitude at palmer is averagely 40 m s more equatorward than that at mh the zonal wind is dominantly westward at palmer and eastward at mh the annual variation of neutral wind especially the zonal component is much less symmetric between the two sites than the local time variation the empirical horizontal wind model shows a good agreement with the observations in both local time and annual variations

physical modelling of gelifluction and frost creep some results of a large scale laboratory experiment an experimental slope was constructed in a 5 m 5 m square refrigerated tank the slope was formed of four sections each consisting of regolith soil collected from a distinct bedrock lithology the four lithologies utilized were granite limestone mudstone and slate the slope was subjected to freezing and thawing from the surface downwards water was supplied at the base of the soil during freezing frost heaving and surface downslope soil movement were determined after each of 15 freezing cycles and the profiles of soil movement with depth for each soil type were measured at the end of the 15th cycle the experimental soils were non cohesive those derived from granite and limestone were respectively sandy and gravelly in texture while those derived from mudstone and slate were silt rich mass movement in the granite and limestone soils was due mainly to frost creep and was associated with the growth of needle ice in the mudstone and slate soils gelifluction was dominant as a result of high moisture contents caused by the melting of segregation ice mean per cycle rates of downslope soil transport for the granite limestone mudstone and slate soils were 5 8 cm3 cm 1 6 9 cm3 cm 1 21 2 cm3 cm 1 and 31 2 cm3 cm 1 respectively units referring to the volume of soil passing a unit width of slope per cycle mass movement rates were shown to be strongly related to the silt content of the soils