latitudinal and seasonal variations of inertial gravity wave activity in the lower atmosphere over central china 1 gravity wave activities and background dynamical structure in the troposphere and lower stratosphere tls over five stations at latitudes from 10 n to 40 n were statistically studied by using the data from radiosonde observation on a twice daily basis at 0800 and 2000 lt the background dynamical structure exhibits evident latitudinal and seasonal variations and has a profound influence on inertial gravity waves in the tls in the analyses of inertial gravity waves according to the background structures the observation height coverage is divided into two segments which are the tropospheric 0 10 km and lower stratospheric segments 18 25 km the observational results indicate that the tropospheric jet is the most important excitation source for gravity waves both in the troposphere and lower stratosphere and it plays different roles in determining the morphology of gravity waves in these two segments the jet excited gravity waves in the troposphere can propagate both upward and downward and only part of the upward propagating waves can penetrate into the stratosphere because of the doppler shifting by the jet while in the lower stratosphere gravity waves excited by the tropospheric jet propagate upward most differences between the tropospheric and lower stratospheric results can be explained from the linear dispersion relations of gravity waves and the doppler shifting by the strong tropospheric jet however such an explanation is qualitative rather than quantitative generally the observations reveal that the tropospheric gravity waves are mainly controlled by their excitation sources implying the wave characteristics may be regarded as at least an indicator of the wave excitation source characteristics these results suggest that in order to attain a more realistic source parameterization for gravity waves propagating in the middle and upper atmosphere more attention should be paid to the gravity waves in the troposphere moreover the causes of the pronounced peak of lower stratospheric gravity wave intensity at tropical latitudes revealed by previous observations are also discussed

some guidelines in reconstructing ancient sea conditions from wave ripplemarks abstract the collection of substantial field data on wave ripple mark spacing wavelength steepness grain size and symmetry index from the miocene burdigalian sandstones of western switzerland has allowed apparently close reconstruction of sea conditions results indicate however that ancient wave reconstructions must be restricted at present to data from relatively steep ripple marks vfi less than 7 5 i e vortex ripples data from the flatter ripple marks post vortex types formed at high oscillatory shear stresses do not provide reasonable estimates of wave conditions penecontemporaneous overwashing and or post depositional compaction ripple formation near the destruction condition rather than the threshold of sediment movement orbital diameters far exceeding ripple spacing and superimposed unidirectional currents are all factors which seriously affect wave reconstructions evaluation of ancient wave conditions provides insight into geologically important phenomena such as local water depth and basin size

a note on photography in structural geology abstract when photographs of outcrops are required for detailed and or accurate structural work the photographic image should be parallel to the outerop surface a method has been developed which allows oblique photographs to be corrected when processed the method imposes certain restrictions on the combinations of camera and enlarger lenses which will yield a correctly proportioned print and graphs are presented which predict suitable combinations for a wide range of conditions the technique has been successfully applied to several problems one of which is presented as an illustrative example

seasonal variation of momentum flux in the mesosphere observed with the mu radar we have regularly monitored mesospheric winds at 60 85km for three years with the mu radar 35 n 136 e and have found that the variance of wind velocity fluctuations for periods from 5 min to 2 hr shows a semi annual variation with a significant peak in summer centered in july and irregular enhancements in winter the zonal momentum flux induced by gravity waves shows eastward and westward maxima in july august and december february respectively typical eastward accelerations at the 70km altitude range from 7 to 13 m s day and from 8 to 11 m s day in summer and winter respectively which agree fairly well with theoretical predictions

an investigation of gravity wave activity in the low latitude upper mesosphere propagation direction and wind filtering horizontal phase speeds of up to 80 m s 1 the large scale band wave patterns horizontal wavelength between 10 and 60 km exhibited a clear seasonal dependence on the horizontal propagation direction propagating toward the southeast during the summer months and toward the northwest during the winter the direction of propagation was observed to change abruptly around the equinox period in mid march and at the end of september using a numerical simulation of gravity wave propagation in a seasonally variable climatological wind field we have determined that the observed anisotropy in the wave propagation directions can be attributed to a strong filtering of the waves in the middle atmosphere by stratospheric winds index terms 0310 atmospheric composition and structure airglow and aurora 3332 meteorology and atmospheric dynamics mesospheric dynamics 3360 meteorology and atmospheric dynamics remote sensing keywords airglow winds gravity waves wind filtering imager

statistical study of atmospheric gravity waves in the mesopause region observed by a lidar chain in eastern china atmospheric gravity wave activities in the mesopause region have been observed and statistically investigated with a sodium lidar chain in eastern china in total there were 471 gravity waves identified from over 5400h of observations at hainan 19 99 degrees n 110 34 degrees e hefei 31 87 degrees n 117 23 degrees e and beijing 40 47 degrees n 115 97 degrees e these waves typically had vertical wavelengths of z 2 4km observed periods of t ob 1 4h amplitude growth factors of 0 025 similar to 0 05km 1 and wave amplitudes of ae 90km 1 5 6 strong systematic parameter relationships were found and they agree with the predictions of diffusive filtering theory statistical results show that the seasonal variability of gravity wave activity had a summer maximum and winter minimum characteristics in the mesopause region over eastern china a qualitative interpretation is proposed regarding the seasonal and geographic variability observed by the lidar chain based on analysis of source properties and influences from background wind which vary by season

ichnology and depositional environment of the middle devonian valentia island tetrapod trackways south west ireland abstract nine tetrapod trackways are described from the middle devonian continental valentia slate formation on the north eastern coast of valentia island in county kerry ireland the trackways occur at three sites dohilla coosadillisk and culoo head the latter two being recorded for the first time morphological and taphonomic analyses of the trackways suggest they were made by populations of similar tetrapods but of varying size body length 0 5 to 1 m width 0 15 to 0 30 m that moved in some cases by terrestrial locomotion and in others possibly by a slow paddling gait while the substrate was submerged by very shallow floodwater sedimentological facies analysis of the trackway bearing sequences has been carried out for the first time and shows that the preserved trackways are associated with the late stages of 1 a principal river channel margin coosadillisk 2 a minor floodplain drainage channel culoo head and 3 a sand rich crevasse splay medial alluvial ridge environment dohilla the valentia island tetrapods inhabited marginal environments of proximal river channels 170 km northwards into the continent from postulated shallow marine habitats as they evolved this capability over a potential 4 5 million year period during the middle devonian

lidar observations of gravity waves and their spectra near the mesopause and stratopause at arecibo abstract the uiuc cedar rayleigh na lidar was operated for approximately 160 h on 30 nights in january march and april 1989 at the arecibo observatory 18 n 67 w as part of the aida act 89 campaign during this period 38 quasi monochromatic gravity waves were observed in the stratopause region 25 55 km and 62 waves were observed in the mesopause region 80 105 km the event rates in both regions are approximately half those observed at the midlatitude site of urbana the characteristics of the waves in both regions are similar measured vertical wavelengths range from 1 1 to 17 km vertical phase velocities from 6 to 270 cm s 1 observed periods from 5 min to 65 h and amplitudes relative atmospheric density variations 0 4 to 17 the wave amplitudes in the stratopause region are on average half the values for waves in the mesopause region with similar periods and vertical wavelengths vertical wavenumber spectra of density perturbations in both regions exhibit power law dependencies with slo

gravity waves in the upper mesosphere over antarctica lidar observations at the south pole and syowa lidar observations of the mesospheric na layer were made at the south pole 90 s and syowa 69 s during the winters of 1990 and 1985 respectively these observations are used to characterize the gravity wave activity in the upper mesosphere at both sites strong wave activity is observed throughout the winter at both the south pole and syowa and shows remarkable similarity with observations from several midlatitude and low latitude sites the quasi monochromatic gravity waves exhibit the same general relationships between their wavelengths observed periods and amplitudes as observed at lower latitudes the average growth length of these waves is approximately 26 km indicating that the wave field at both antarctic sites is strongly influenced by dissipation and saturation processes the spectra and variances of the density perturbations associated with quasi random wave field at the south pole are reported the vertical wavenumber and temporal frequency spectra follow power law shapes the mean index of the vertical wavenumber spectrum is 2 4 and the mean characteristic wavelength is 14 km the mean index of the temporal frequency spectrum is 1 7 the mean density variance at the south pole is 5 7 2 and is similar in magnitude to that observed at a variety of lower latitude sites with no tropospheric convection during the polar night and little orographic forcing over the relatively featureless antarctic plateau these observations suggest that nonlinear processes rather than the source characteristics primarily determine the characteristics of the gravity wave field in the upper mesosphere these observations show two other distinct features the mean na layer over antarctica is significantly lower and broader centroid height 90 km and rms width 4 8 km than at lower latitudes reflecting the stronger downwelling and warmer winter temperatures in the mesopause region at high latitudes strong coherent oscillations were observed in the bottomside density contours of the na layer with periods close to the inertial period these oscillations were also observed in oh airglow measurements and appear to be associate with planetary scale waves

tectono sedimentary ripples in devonian shallow marine siliciclastic sediments southern ireland abstract tectonically altered sedimentary ripples occur commonly in the marine devonian old head sandstone formation of southern ireland these tectono sedimentary ripples are dominantly wave produced and have sharp v shaped troughs where spaced pressure solution cleavage surfaces are located at a high angle to bedding the ripples control the spacing of cleavage and influence cleavage orientation the profile shape of the ripple is a function of stress refraction and concentration within the stiff sandstone layers of a multilayer sequence ripple symmetry is affected by tectonic deformation which plays an important role in the development of tectono sedimentary ripples tectonically flattened wave produced ripples occur where cleavage is oriented parallel to bedding due to an anomalous deformation in the old head sandstone formation at galley head selected ripple profiles have been undeformed by computer simulation to reconstruct ancient wave conditions this use of tectono sedimentary ripples for this purpose has its limitations and a number of guidelines are given for application of this technique elsewhere

traveling ionospheric disturbances associated with the tropospheric vortexes around qinghai tibet plateau to show the relationship between the traveling ionospheric disturbances tids observed in central china and the vortexes corresponding to the topography of qinghai tibet plateau the wave parameters frequency wavenumber and propagation azimuth and the exciting sources of the tids are statistically analyzed under the base of observation of an hf doppler array it is found that the observed tids propagate mainly in the northeastward ne and southeastward se directions the backward ray tracing shows that the sources of ne and se tids are respectively located in the southeastern and northeastern edges of qinghai tibet plateau i e in the lee sides of the bulging terrain of the plateau where the vortexes are more probably produced the and geographical distributions as well as their seasonal variations of the occurrence rate of both the tid sources and the vortexes are very coincident with each other this leads us to suggest that the observed tids be excited by the tropospheric vortexes which in turn are related to the topography of the plateau

structural evolution of the irish variscides the effects of the variscan orogeny on the upper palaeozoic succession are recognizable throughout central and southern ireland the deformation can be zoned using structural styles and trends which illustrate a northward decrease in deformation intensity coupled with increasing control by pre variscan structures in the basement the most intense deformation occurs to the south of the dingle dungarvan line where shortening approaches 50 as a result of layer parallel shortening followed by buckling and finally thrusting the deformation is considered to have developed above a shallow dipping sole thrust which has been located offshore by the swat seismic reflection profiles cross faults which are common throughout the orogen resulted from n s shear couples this is consistent with their origin as accommodation structures due to differential shortening along strike the original shape of the munster basin has exerted a control on the distribution and overall facing of the major structures the sole thrust extends to the north of the dingle dungarvan line and the structural zonation of the orogen is due to variations in the stratigraphic level of this thrust the leinster massif is considered to be essentially autochthonous slip on the sole thrust decays towards the massif which acted as a rigid passive block and was partially responsible for the arcuate trend of the orogen

reconstruction of ancient sea conditions with an example from the swiss molasse ancient sea conditions can be estimated from the grain size spacing and steepness of preserved ripple marks the element of greatest uncertainty in such reconstructions is the relationship between near bed orbital diameter of water particles and the ripple spacing this relationship is simple for vortex ripples of high steepness but is problematical for the low steepness forms known as post vortex rolling grain or anorbital ripples the existence field for wave ripples is between the threshold velocity for sediment movement and the onset of sheet flow most low steepness forms occurring close to the bed planation threshold a range of maximum period of formative waves can be obtained using combinations of orbital diameter and orbital velocity assuming linear wave theory to be a reasonable approximation probable wave heights wave lengths and water depths can be investigated using the transformation of wave parameters in shallowing waters and the constraints on wave dimensions provided by the wave breaking condition given reasonable estimates of wave height crude estimates of wave power allow a comparison of ancient wave influenced sequences with modern counterparts wave ripple marks preserved in the upper marine molasse of western switzerland have been investigated results which are in agreement with regional geology suggest deposition in a seaway of approximately 100 km width where moderate period waves t 3 6 s were generated the depositional facies belts were adjusted to the prevailing waves tides and fluvial outflows

interplay between river discharge and topography of the basin floor in a hyperpycnal lacustrine delta basin floor topography influences the flow path of hyperpycnal plumes and delta morphology during progradation of the red river delta in lake texoma usa the red river discharge is typically a hyperpycnal plume due to elevated total dissolved solids because the river plume is a bottom hugging hyperpycnal flow lake bathymetry and topography strongly influence deposition and subsequent delta morphology in addition to elevated total dissolved solid concentrations compared with lake texoma water the density contrast of the red river outflow is increased by high suspended sediment concentrations during high discharge events steep lateral slopes in the lake texoma basin deflect hyperpycnal river plumes and subsequently change the delta progradation direction before the delta reaches the opposite bank of the lake analysis of multi temporal aerial and satellite images indicates that the hyperpycnal delta follows the steepest lake bottom gradients corresponding to the pre impoundment river thalweg i e bypassing shallow parts of the lake an analytical model for the hyperpycnal plume trajectory indicates plume deflection during low discharge or high discharge events towards the deepest part of the basin the magnitude of plume deflection is a function of river discharge and basin margin gradients plume deflection can vary between 10 and 80 from the channel axis towards the old river thalweg the high deflection appears in the case of maximum basin side gradients of 12 8 and in conditions of low river discharge during low discharge periods the red river delta builds a lobate shape with multiple terminal distributary channels whereas during high discharge periods the red river delta builds an elongate shape with a single large distributary channel the elongate morphology of the delta is formed through the development of a single distributary channel and abandonment of the other distributaries therefore the lobate shaped delta is expected to be preserved in the rock record

lidar temperature measurements of gravity waves over kuhlungsborn 54 n from 1 to 105 km a winter summer comparison 1 since august 2002 temperature measurements from 1 to 105 km are performed at the leibniz institute of atmospheric physics in kuhlungsborn 54 n with a combination of different lidars results from 14 nights in winter and 31 in summer are presented nightly mean profiles and fluctuations with a temporal and vertical resolution of 15 min and 1 km respectively are derived in both seasons wave energy propagates upward phase propagates downward with vertical phase speeds of 0 25 to 1 9 m s phase speeds are generally larger in the mesosphere compared to the stratosphere because of decreasing static stability wave periods are found in the entire range of 1 8 hours given by experimental constraints with no preference for particular periods the observed vertical wavelengths cover the entire instrumental range of 5 50 km but the majority lies below 22 km in both seasons in single nights a few waves up to three dominate the wave spectrum and represent 45 65 of the entire variability wave amplitudes generally increase with altitude with a scale height of 18 22 km i e less than expected 14 km for propagation conserving momentum flux density the gravity wave energy loss changes with altitude and is different in both seasons local fluctuation minima nodes are often observed frequently colocated with convective instabilities temperature fluctuations are generally smaller in summer compared to winter maximum values are 10 and 25 k respectively applying gravity wave polarization relations to the mean winter and summer lidar temperature profiles the difference of fluctuations is basically determined by the background conditions especially at 60 80 km

transgressive facies in the south munster basin ireland this paper describes the sedimentation style associated with the basal carboniferous transgression in southern ireland and the influence which this event had on the palaeogeography of the region the transgression as marked by the base of the carboniferous succession is shown to represent one of several genetically related transgressive pulses which commenced during the late devonian at this time an east west trending graben the south munster basin developed in southern ireland this was initially a non marine depositional site in which sediment was derived from the north and west subsidence and eustatic sea level rise resulted in a marine transgression which proceeded in a rhythmic style resulting in a number of transgressive stillstand pulses the first transgressive pulse t1 advanced in a westerly direction along the basin axis resulting in the development of an epicontinental like sea the shoreline remained essentially static along the northern basin margin initially until a second transgressive pulse t2 resulted in expansion of the marine area the latter proceeded by gradual northward erosive advance of a barred coastal area as far as the northern basin margin where the stability of the bounding platform halted its progress erosion of the barrier shoreface was insufficient to destroy all the backbarrier lagoonal deposits which are preserved as a thin transgressive diachronous unit which grades northwards to a coastal alluvial plain immediately preceding the basal carboniferous transgression t3 a shallow wave dominated storm influenced shelf sea occupied the basinal area two sublittoral sand bar complexes developed on the shelf under the influence of shore parallel current regimes apparently derived from source areas located on either side of the epicontinental sea the basal carboniferous transgression took place in two pulses the first t3a resulted in a rapid reduction in sand supply to the shelf and deposition of clay the barrier shoreline responded by erosively retreating across the lagoon leaving a transgressive lag in its wake its northwards advance was however limited due to the relative stability of the northern platform sand supply to the shelf was completely terminated in the second pulse t3b and the barrier rapidly migrated erosively across the northern platform for a considerable distance such that the coastal plain is overlain by a thin transgressive lag this transgressive phase was immediately followed by shoreline stillstand and progressive shallowing of the shelf an open sandy shelf developed on which offshore sand bars accumulated under a storm and wave dominated regime clay deposition continued in the deeper part of the basinal area but was eventually terminated as the shelf sands prograded centripetally into the basin the main factor that controlled the style of the overall transgression was an interplay between eustatic sea level rise and basin subsidence the rate of relative sea level rise together with the effect of differential subsidence and fluvial input from the north appear to have diminished with time the rate at which successive transgressive pulses advanced northwards shows an overall progressive increase

a shoreline evolution model considering the temporal variability of the beach profile sediment volume sediment gain loss abstract the prediction of shoreline variability along sandy coastlines is a valuable skill for a broad range of coastal engineering applications currently there are multiple proposals in the literature for equilibrium cross shore shoreline evolution models based on a constant equilibrium condition correlated with the shoreline position the aim of this paper is to present an extension of an existing equilibrium shoreline evolution model adding a rate of change component which in turn modifies the relationship between the equilibrium shoreline position and the incident wave energy as a function that advances or retreats over time the proposed model is applied to two study sites on the spanish coast on the one hand one and a half years of shoreline position data obtained from a video camera system at nova icaria beach catalonia are used to evaluate the shoreline evolution during a period of sediment contribution which is attributed to a sand bypass coming from bogatell beach on the other hand 16 years of shoreline position data acquired from beach profile surveys in campo poseidon huelva are used to reproduce the shoreline evolution taking into account the trend of sediment loss due to sediment drift alongshore the results obtained from both study sites using the proposed model show overall good performance the model successfully represents the general shoreline erosion accretion oscillations and the progressive trend of sediment gains or losses through the evolutionary relationship between the equilibrium shoreline position and the incident wave energy

the palaeoenvironment and deformation of beaconites like burrows in the old red sandstone at gortnabinna sw ireland the gortnabinna area contains a number of well preserved deformed burrows within the fluviatile old red sandstone of s ireland detailed logging of the local succession enables subdivision into four facies facies 1 represents sheet flood deposits facies 2 ephemeral stream channels facies 3 marginal sheet flood deposits and facies 4 low energy settling of fines the burrows occur in facies 1 and 4 the sediments are now folded into a large upright westward plunging anticline the fold has a well developed axial planar cleavage and is extended along strike by listric normal faults the burrows in facies 1 were originally circular and orthogonal to bedding and reveal a n s layer parallel shortening strain of 2 1 followed by a shear strain of 1 48 during folding these burrows have a bimodal distribution of diameters with peaks in the ranges 50 80 and 110 170 mm the burrows of facies 4 are sub parallel to the bedding plane and are generally curved with a maximum width of 180 mm and lengths of up to 2 3 m these burrows display passive infill following abandonment the burrows are morphologically similar though distinct from beaconites barratti which has been described from elsewhere in the old red sandstone and are tentatively interpreted as lungfish burrows

global estimates of gravity wave momentum flux from high resolution dynamics limb sounder observations analyzed to derive global properties of gravity waves we describe a wavelet analysis technique that determines covarying wave temperature amplitude in adjacent temperature profile pairs the wave vertical wavelength as a function of height and the horizontal wave number along the line joining each profile pair the analysis allows a local estimate of the magnitude of gravity wave momentum flux as a function of geographic location and height on a daily basis we examine global distributions of these gravity wave properties in the monthly mean and on an individual day and we also show sample instantaneous wave events observed by hirdls the results are discussed in terms of previous satellite and radiosonde observational analyses and middle atmosphere general circulation model studies that parameterize gravity wave effects on the mean flow the high vertical and horizontal resolution afforded by the hirdls measurements allows the analysis of a wider range of wave vertical and horizontal wavelengths than previous studies and begins to show individual wave events associated with mountains and convection in high detail mountain wave observations show clear propagation to altitudes in the mesosphere

flexural shear in a periclinal fold from the irish variscides abstract periclinal folds occur in a structural culmination in the centre of the irish variscan fold belt the culmination marks a zone of enhanced shortening which is associated with a locally attenuated stratigraphy and an anomalous deformation sequence with respect to the remainder of the orogen originally vertical burrows have been used along with cleavage fold relations to study both the three dimensional evolution of the periclinal folding and the temporal relationship between folding and cleavage as well as cleavage forming flattening strains the burrows record along strike shear related to the propagation of the periclinal folds a comparison with strain measurements made outside the culmination zone shows that the galley head area suffered higher strains integration of field data with published analyses of plasticine modelling of periclinal folds yields models for the propagation of a pericline and for the geometry of its lateral terminations

hydrodynamics and sedimentation in wave dominated coastal environmentsreconstruction of ancient sea conditions with an example from the swiss molasse ancient sea conditions can be estimated from the grain size spacing and steepness of preserved ripple marks the element of greatest uncertainty in such reconstructions is the relationship between near bed orbital diameter of water particles and the ripple spacing this relationship is simple for vortex ripples of high steepness but is problematical for the low steepness forms known as post vortex rolling grain or anorbital ripples the existence field for wave ripples is between the threshold velocity for sediment movement and the onset of sheet flow most low steepness forms occurring close to the bed planation threshold a range of maximum period of formative waves can be obtained using combinations of orbital diameter and orbital velocity assuming linear wave theory to be a reasonable approximation probable wave heights wave lengths and water depths can be investigated using the transformation of wave parameters in shallowing waters and the constraints on wave dimensions provided by the wave breaking condition given reasonable estimates of wave height crude estimates of wave power allow a comparison of ancient wave influenced sequences with modern counterparts wave ripple marks preserved in the upper marine molasse of western switzerland have been investigated results which are in agreement with regional geology suggest deposition in a seaway of approximately 100 km width where moderate period waves t 3 6 s were generated the depositional facies belts were adjusted to the prevailing waves tides and fluvial outflows

wavelet analysis of stratospheric gravity wave packets over macquarie island 2 intermittency and mean flow accelerations we calculate the mean flow accelerations due to gravity wave packets observed in the lower stratosphere over macquarie island 55 s 159 e between february 1994 and april 1995 the parameters of the wave packets were extracted from twice daily radiosonde soundings using a wavelet based analysis method introduced by zink and vincent this issue the deduced wave parameters are used to directly compute momentum flux profiles in the lower stratosphere and the shortcomings of this approach to assess mean flow accelerations are discussed we then use the observed wave packets as an input spectrum in a linear ray tracing model the vertical extent of the detected wave packets allows us to define an expression for wave intermittency which enables us to compute zonal accelerations in the stratosphere and mesosphere in the stratosphere the waves produce an acceleration of the mean flow in accordance with predictions in the mesosphere the inferred wave drag is 2 3 times larger than previous observational and theoretical estimates

climatology of medium scale traveling ionospheric disturbances observed by a gps network in central china 1 the 15 month climatology of medium scale traveling ionospheric disturbances mstids during a solar minimum period has been constructed from observations of a dense gps receiver array in central china in total 793 mstid events are identified with peaks in occurrence at 1500 lt and 0100 lt the occurrence of mstids decreases following an increase in geomagnetic activity with 46 of the mstids occurring in the daytime daytime mstids are characterized by a major occurrence maximum around the winter solstice and by an equatorward propagation direction the period phase velocity azimuth and amplitude of daytime mstids are 20 60 min 100 400 m s 130 270 and 0 8 1 5 respectively the remaining 54 of the mstids occurred at night and were characterized by a peak in occurrence at the summer solstice and by a southwestward propagation direction the period phase velocity azimuth and amplitude of nighttime mstids are 20 70 min 50 230 m s 170 300 and 2 7 respectively the propagation directions and the seasonal behaviors support the view that daytime mstids are an ionospheric manifestation of atmospheric gravity waves from the lower atmosphere while a possible excitation mechanism of nighttime mstids is the electrodynamics process caused by plasma instability in the f layer

analytical method for estimating palaeowave climate and water depth from wave ripple marks analytical expressions are developed for evaluating palaeodepth and palaeowave conditions from wave ripple marks palaeodepth and palaeowave climate estimates can be extremely powerful predictors in reconstructions of vertical movements related to basin subsidence local and regional ancient wave climate trends and the basin shape the analytical expressions developed herein are applied to wave ripple marks preserved in the lower marine molasse of switzerland western austria and southern germany the results suggest that in contrast to traditional concepts of an eustatic sea level change the lower marine molasse regression was a result of mainly depositional processes the subsidence rate greatly exceeded the rate of sea level fall over a wide geographical area furthermore the widening of the lower marine molasse basin to the ene is well documented by the increase of the ancient wave period and wave power calculated from wave ripple marks found in storm deposits

medium frequency radar studies of gravity wave seasonal variations over hawaii 22 n 160 w 1 using simple numerical filters estimates of wind variances with period bands of 0 1 to 1 hour and 1 to 5 hours have been derived from data taken with the medium frequency radar on the island of kauai hawaii 22 n 160 w the observations cover altitudes of 70 to 90 km and extend over the years 1990 2000 the results show seasonal and interannual variations of the wind variances which can be attributed to atmospheric gravity waves the mean zonal wind has mainly an annual variation below an altitude of 83 km and a semiannual variation above the gravity waves have maximum intensity at the solstices below 83 km but at higher altitudes the times of the maxima shift to the equinoxes numerical simulations suggest this behavior results from the dependence of gravity wave generation and propagation on the background wind and temperature

the use of landsat imagery to map fluvial sediment discharge into coastal waters abstract the sediment discharge of the river yare via breydon water estuary into the north sea has been studied sixty samples were taken the average of each sample in the band tm1 was used to estimate the concentrations of suspended solids sixty samples were used to extract information from the reflective bands tm1 tm4 the spatial distribution of suspended solids as well as the spatial and vertical extent of different turbidity levels were then detected estimated and mapped based on this information the water circulation pattern at the mouth of river yare was identified and mapped the influence of wind velocity and direction as well as the tidal current conditions prior to and during the image time on turbidity and water circulation patterns were examined the tidal influence was found to be the most significant factor in shaping and guiding water circulation near the mouth of river yare