nocturnal low level jet and atmospheric streams over the rain shadow region of indian western ghats spatial and temporal characteristics of a nocturnal low level jet llj on the east side of the western ghat mountain range over india s west coast and processes leading to the formation of the jet are discussed the boundary layer jet has a regional scale extent as revealed by high resolution advanced research weather research and forecasting arw model simulations and contributes to the formation of atmospheric streams of water vapor over the selected land regions simulations indicate that the formation of llj is mainly attributed to the baroclinicity of the valley atmosphere due to the gently rolling terrain which is assisted by the persistence of an unstable residual layer above the developing stable boundary layer in the valley and cooling over the slopes prior to the formation of llj the boundary layer is dominated by deep roll circulations the llj followed a gust front zone associated with a mountain wave the low level flow below the jet is decoupled from the upper level flow as a result of strong vorticity below the jet and suppression of turbulence at the jet core a conceptual model for the boundary layer interactions dynamics of the mountain wave llj etc are proposed for western ghat region

gravity wave excitation during the coastal transition of an extreme katabatic flow in antarctica abstractthe offshore extent of antarctic katabatic winds exerts a strong control on the production of sea ice and the formation of polynyas in this study we make use of a combination of ground ba

nocturnal meso beta basin and katabatic flows on a midlatitude island abstract a mesoscale simulation for the island of majorca spain in the western mediterranean sea is used to study the nocturnal system of winds under weak synoptic pressure gradients a very high vertical resolution is used in the first 500 m above ground level to characterize with large detail the thin circulations close to ground namely basin and katabatic flows it is found that the island the basin and the slope scales interact strongly especially when a quasi steady state is reached in the second part of the night a high mountain range creates a high pressure area upwind where local winds can develop katabatic flows converge to the valleys where they interact with a cold pool which is advected slowly to sea by the land sea night breeze effect combined with a topographic forcing the katabatic flows experience small entrainment at the top and have well defined characteristics the results are partially confirmed by the observations and some satellite images

some aspects of the variation with time of katabatic flow over a simple slope features of the variations in katabatic flow along a simple slope in athens greece are examined both observationally and from a simplified theoretical basis when undisturbed periods of established flows are selected it is observed that the velocity and temperature fluctuations reveal characteristics which are in agreement with the theory proposed by fleagle interesting implications of the theory are discussed such as the effects of prescribing a decreasing cooling rate throughout the night or of taking into account the vertical structure of the katabatic layer

transient cold air drainage down a shallow valley abstractdrainage of cold air down a small valley and associated near surface wind maxima are examined from 20 stations with sonic anemometers at 1 m and from a 20 m tower that includes six sonic anemometers in the lowest 5 m deployed in the shallow cold pool experiment scp the small valley is about 270 m wide and 12 m deep with a downvalley slope of 2 3 the momentum budget indicates that the flow is driven by the buoyancy deficit of the flow and opposed primarily by the stress divergence while the remaining terms are estimated to be at least an order of magnitude smaller this analysis also reveals major difficulties in quantifying such a budget due to uncertainties in the measurements sensitivity to choice of averaging time and sensitivity to measurement heights wind maxima occur as low as 0 5 m in the downvalley drainage flow the lowest observational level the downvalley cold air drainage and wind maxima are frequently disrupted by transient modes that sometimes lead to significant vertical mi

the collisional knot in liguria a series of 8 new seismic refraction profiles were computed as extensions of the borehole controlled reflection profiles of the po plain into the northern apennines and the ligurian alps they help to more clearly define the subsurface structure of this intricate ligurian knot in particular it has been possible to identify a number of high velocity bodies and they may be correlated with such geological entities as the adriatic mesozoic ophiolites of the apenninic liguride nappes and ophiolites or mesozoic carbonates underlying the antola flysch in the alpine part of the knot when combining the refraction and reflection lines these bodies appear to be bounded by important dislocation surfaces such as the padanide sole thrust plio pleistocene the villalvernia varzi line oligo miocene the ottone levanto line oligo miocene and the volpedo valle salimbene fault oligo miocene reactivated as a transfer fault in the plio pleistocene the 3d geometry may be interpreted in terms of regional kinematics and is compatible with a model that envisages an oligo early miocene nw translation of the adriatic indenter coupled with collapse in the provencal ligurian sea and rotation of the sardinia liguria complex into the roll back of the adriatic subduction zone the refraction interpretations extending to a depth of 15 km are supplemented by data on the moho configuration obtained for the european geotraverse the moho appears to be dissected into a series of patches which may be interpreted in terms of the shallow crustal configuration and its history in particular the deepest patch appears to be terminated by the volpedo valle salimbene fault which consequently would displace the entire crust

analysis of gravity waves generated at the top of a drainage flow abstract drainage or katabatic flows are common mesoscale circulations established as a result of differential radiative cooling of near surface air masses in sloping terrain the initial irruption of these flows with sudden shifts in wind speed and direction may result in vertical displacements of air parcels from their equilibrium position which prove to be a common source of internal gravity waves this paper illustrates this mechanism and describes the main features of the oscillations following the study of observational data gathered throughout one night during the stable atmospheric boundary layer experiment in spain 2006 sables2006 field campaign pressure differences measured by microbarometers set at different levels of a tower help to interpret the evolution of other atmospheric variables provide a detailed picture of the irruption of a drainage current and reveal the formation of gravity waves at its top the main parameters of the waves are derived from wavelet cross correlation of p

nonlinear teleseismic tomography at long valley caldera using three dimensional minimum travel time ray tracing the authors explore the impact of three dimensional minimum travel time ray tracing on nonlinear teleseismic inversion this problem has particular significance when trying to image strongly contrasting low velocity bodies such as magma chambers because strongly refracted and or diffracted rays may precede the direct p wave arrival traditionally used in straight ray seismic tomography they use a simplex based ray tracer to compute the three dimensional minimum travel time ray paths and employ an interative technique to cope with nonlinearity results from synthetic data show that their algorithm results in better model reconstructions compared with traditional straight ray inversions the authors reexamine the teleseismic data collected at long valley caldera by the u s geological survey the most prominent feature of their result is a 25 30 low velocity zone centered at 11 5 km depth beneath the northwestern quandrant of the caldera beneath this at a depth of 24 5 km is a more diffuse 15 low velocity zone in general the low velocities tend to deepen to the south and east the authors interpret the shallow feature to be the residual long valley caldera magma chamber while the deeper feature may represent basaltic magmas ponded in the midcrust the deeper position of the prominent low velocity region in comparison to earliermore tomographic images is a result of using three dimensional rays rather than straight rays in the ray tracing the magnitude of the low velocity anomaly is a factor of approximately 3 times larger than earlier models from linear arrival time inversions and is consistent with models based on observations of ray bending at sites within the caldera these results imply the presence of anywhere from 7 to 100 partial melt beneath the caldera 40 refs 1 fig 1 tab less

analysis of borehole seismograms from long valley california implications for caldera structure a three component seismometer was emplaced in a borehole in long valley caldera for a period of 2 months to record local earthquakes to the south mostly in the sierra nevada the seismic records were plotted in depth versus time sections to produce vertical hypocentral profiles for both the vertical and horizontal components the data collected and displayed in this way provide good resolution of the crustal structure at depth and avoid the attenuation and complications introduced by the near surface caldera fill the record sections were then modeled with two dimensional ray tracing to match the observed travel times although nonreversal of the profiles and uncertainties in hypocentral locations introduce ambiguities the final interpretation reveals two separate low velocity bodies which we have tentatively identified as magma beneath the resurgent dome in long valley the first of these is a small 2 km by 6 km body with a depth to top of approximately 3 7 km beneath the surface at the southern end of the resurgent dome the other body appears larger and lies at a depth of 5 5 km beneath the northern end of the resurgent dome

constraints on the upper crustal structure of the long valley mono craters volcanic complex eastern california from seismic refraction measurements during the summers of 1982 and 1983 field work was completed on 10 new seismic refraction profiles in the long valley mono craters region located within the technically active zone between the eastern sierra nevada and the basin and range province the four profiles presented here sample the upper 7 10 km of the crust within the western half of long valley cladera the mono craters ring fracture system and the normal crust north and northeast of long valley the entire area shares a common crystalline basement consisting primarily of mesozoic granitic rocks at a depth of 2 km beneath the topographic surface the p wave velocity is uniformly 5 6 km s beneath which the velocity increases with a gradient of about 0 1 s 1 clear secondary arrivals observed on a profile crossing the west part of the caldera support evidence from 1972 seismic refraction profiles for a reflecting boundary at a depth of 7 8 km beneath the west margin of the resurgent dome which may represent the top of a magma chamber structural details resolved in the upper 2 km of the crust lead to the following conclusions 1 p wave velocities in the crystalline basement at depths shallower than 2 km vary from 3 6 to 5 0 km s this variation reflects differences in the degree of fracturing of the upper portion of the basement 2 an apparently homogeneous basement in the upper 7 10 km beneath the mono craters ring fracture system indicates that any extensive magma chamber must be at least 10 km deep there 3 the downdropped crystalline basement beneath the western half of long valley caldera dips genty 5 10 to the northeast apparent offsets along steeply dipping caldera bounding faults are 1 0 1 7 km along the northern western and southern sides of the caldera with largest offsets in the north 4 rocks forming the caldera fill fall into essentially three p wave velocity groups from the surface downward these velocity groups are 100 400 of 1 2 1 8 km s material corresponding to unconsolidated fluvial or lacustrine deposits or highly fractured rhyolite flows 200 400 m of 2 8 3 1 km s material corresponding to sparsely jointed postcaldera rhyolite rhyodacite and basalt flows and approximately 1000 m of 3 9 4 4 km s material corresponding to deposits of bishop tuff

the development of antarctic katabatic winds and implications for the coastal ocean the influence of katabatic winds on the antarctic coastal waters is examined by using simple models of the ocean and atmosphere a katabatic flow model incorporating coriolis dynamics is solved analytically and another with nonlinear friction is solved numerically to provide wind stress to a two layer coastal ocean model the resulting solutions are evidently the first to incorporate coriolis terms with a thermodynamic equation that includes compressional warming effects the emphasis in this paper is on delineating the parameters that control the relative adjustment of the katabatic wind into alongshore and offshore components by including nonlinear friction it is shown that steeper slopes and weaker stratification tend to direct the wind more toward the ocean it is further demonstrated that the katabatic forcing supports the strong polar easterlies winds from the east along the periphery of the continent and that the offshore extent should be dependent on the atmospheric rossby deformation radius the ocean model shows that significant downwelling occurs at the coast while upwelling is predicted at a distance of the order of the ocean rossby radius an alongshore coastal jet from the east is found in the model and is evidently the manifestation of the east wind drift the upwelling offshore may be a significant aspect of polynya formation and maintenance of the antarctic divergence zone and contribute to the biological productivity of the region

late oligocene miocene sedimentary evolution of the critical alps apennines junction the monferrato area northwestern italy the monferrato is a key area of the alps apennine junction it consists of a tertiary succession resting on apennine related units in turn overridden by the alpine basement the superficial expression of this crustal discontinuity is the rio freddo deformation zone separating the alpine related torino hill domain from the monferrato stratigraphic analyses allow the recognition of different fault bounded oligo miocene successions interpreted as tectonostratigraphic units some of these corresponded to high standing blocks others to subsiding basins the facies distribution reflects a transpressional tectonic regime in this general framework of wrench tectonics sedimentation was influenced by palaeoceanographic factors during the early and latest burdigalian while tectonics played the dominant role during the aquitanian and the late burdigalian the uniform extent and the unconformable basal boundary of the langhian deposits suggest that the different tectonostratigraphic units presently composing the monferrato area were in place by langhian times

the structure of katabatic flows down a simple slope an analysis of the katabatic flow structure is presented based on data collected along a simple slope over a two month period four meteorological stations were deployed along the nearly two dimensional east slope of mt hymettos in greece the study focuses on the momentum and energy budgets of the flows during carefully selected stationary periods with negligible ambient winds in order to achieve a proper selection the mean features of the observed flows are presented along with their response to external winds the observed profiles are successfully compared with the theoretical prandtl profiles bulk quantities of the katabatic layer are compared with proposed experimental values in order to check the representativity of the observed flows these comparisons offer a further test of theoretical considerations and assist in discussions of processes affecting mean flow features the flows were 20 m deep with velocities 1 2 m s 1 during steady state periods the katabatic acceleration was mainly balanced by the surface friction the contribution of advective terms being small the estimated interfacial drag was less important than the surface drag which proved large compared with usually suggested values within the experimental uncertainties values of the drag coefficient of the order of 10 2 seem appropriate the steady state energy balance showed that the downslope advection balanced the turbulent heat flux to the ground surface

modeling gravity and trilateration data in long valley california 1983 1984 during the period july 1982 through july 1984 a series of repeated high precision gravity measurements have been undertaken in and around long valley california data were collected at about 40 sites using three lacoste romberg model g gravity meters at the same time the u s geological survey was conducting a program of high precision line length measurements throughout the same area significant changes were observed with both types of data during the intervals 1982 1983 and 1983 1984 previous work by us has shown that deformation data during the interval 1975 1983 are consistent with a model for the inflation of long valley caldera which includes magma injection beneath the south central caldera at a depth of only 5 km simultaneous inversion of the trilateration and gravity data for the period 1983 1984 shows that most of the previous model is still reasonably consistent with the data and implies injected volumes of between 0 01 and 0 02 km3 additionally uplift during this period occurred along the inyo domes chain of vents and flows indicating perhaps a new source of inflation in the northwest part of the caldera this uplift amounts to a few centimeters and implies a volume increase of perhaps 0 004 km3 at reasonably shallow depth 3 km the total amount of uplift in the northwest is small in comparison to the total uplift centered on the central resurgent dome total vertical displacement well in excess of half a meter for purposes of comparison we examine several models one of which involves injection at the base of the crust this model implies much higher injected volumes as much as 0 15 0 2 km3

review of wave turbulence interactions in the stable atmospheric boundary layer flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods understanding turbulence intermittency and wave turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans the stable atmospheric boundary layer sabl commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces or even daytime over snow and ice surfaces and when warm air is advected over cold surfaces intermittent turbulence intensification in the sabl impacts human activities and weather variability yet it cannot be generated in state of the art numerical forecast models this failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow in which wave turbulence interaction is a potential mechanism for turbulence intermittency a workshop on wave turbulence interactions in the sabl addressed the current understanding and challenges of wave turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory observations and numerical parameterization there have been a number of reviews on waves and a few on turbulence in stably stratified flows but not much on wave turbulence interactions this review focuses on the nocturnal sabl however the discussions here on intermittent turbulence and wave turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general

subsidence stress regime and rotation s of a tectonically active sedimentary basin within the western alpine orogen the tertiary piedmont basin alpine domain nw italy the oligocene to miocene tertiary piedmont basin tpb is located in the nw part of italy at the junction between the apennine and the alpine thrust belts the position of the tpb on top of the alpine apennine orogen poses fundamental questions as to the tectonics of the basin subsidence having undergone little deformation the tpb sediments provide an insight into the stress regime and rotations in the kinematically very complex area surrounding the basin itself in this study we integrate subsidence and structural analysis with measurements of magnetic susceptibility anisotropy ams and natural remanent magnetization nrm in order to better constrain the tectonic kinematics of the basin evolution a major important period of subsidence occurred in the middle miocene involving the whole basin during this period the tpb experienced ne sw directed compression and limited shortening some nw se directed compressional features have been identified and they were probably active during post tortonian times structures associated with north south tension are quite common but the amount of strain that they accommodate is minor in addition this research provides new preliminary data suggesting counterclockwise rotation in the tpb by c 20o which has taken place during middle miocene time

distinguishing primary and resedimented vitric volcaniclastic layers in the burdigalian carbonate shelf deposits in monferrato nw italy abstract a multidisciplinary study including stratigraphic sedimentological biostratigraphic petrographic magnetic fabric and sem analyses has been performed on six volcaniclastic layers vls interbedded in the burdigalian shelf succession of the monferrato nw italy the aim was to distinguish between the volcanic and sedimentary processes that produced these deposits to suggest a depositional model for volcaniclastic sedimentation in a shelf environment and to discuss the use of vls for stratigraphic correlations two kinds of vls have been distinguished single volcaniclastic layers svls and multiple volcaniclastic layers mvls svls are single beds of well sorted vitric siltites mainly consisting of volcanic components and minor terrigenous and intrabasinal grains the vitric fraction mainly consists of blocky fragments they show a very low magnetic anisotropy degree and a prominent magnetic lineation these vls are interbedded in outer shelf marls and are interpreted as primary pyroclastic fall deposits mvls which can be up to 10 m thick show limited lateral continuity and are made up of several decimetre thick graded beds separated by erosional surfaces and consisting of vitric arenites and siltites with about 15 non volcanic components two kinds of mvls have been distinguished 1 type 1 mvls interbedded in storm dominated glaucony rich calcarenites and showing rough low angle cross stratification hummocky cross stratification water escape and load structures these deposits are characterized by a slightly foliated magnetic fabric and are interpreted as storm layers deposited between fairweather and storm wave base 2 type 2 mvls are interbedded in outer shelf marls and are characterized by parallel lamination and by a well developed magnetic foliation they are interpreted as storm induced distal shelf turbidites triggered by storm activity acting in the more internal part of the shelf the monferrato vls resulted from explosive eruptions of volcanic edifices located outside of the basin that produced an extensive tuff blanket that was uniformly distributed on a carbonate dominated shelf above storm wave base the vls were immediately reworked by storm activity and the resulting deposits are type 1 mvls below storm wave base primary pyroclastic fall deposits were preserved corresponding to svls storm induced turbidity currents gave rise to type 2 mvls that were deposited below storm wave base preservation of vls in a shelf environment is hampered by the high energy conditions of the shelf consequently these deposits are characterized by a restricted lateral continuity and their use as correlation tools may be misleading

p sv conversions of teleseismic waves beneath the chyulu hills volcanic field kenya observations of p sv converted waves provide new insights on the structure of the lithosphere beneath the chyulu hills a quaternary volcanic field on the se shoulder of the kenya rift east africa a 3d teleseismic delay time tomography and a seismic refraction model revealed a zone of reduced p wave velocity 3 5 extending from the lower crust into the uppermost mantle limited to about 70 km depth in this paper waveform and particle motion analyses are used to identify p sv conversions in teleseismic recordings and to search for lateral variations of seismic discontinuities data from 9 teleseisms contain clear sv phases within the first 8 seconds of the p coda the depth of the generating interfaces is determined with a local velocity depth function based on the seismic refraction model our results show that there are no lateral depth variations of the conrad 19 21 km and moho 43 45 km discontinuities indicating no large scale modification of the crustal structure through the magmatic processes in the time window between the sv arrivals from the conrad and moho discontinuities additional sv energy is observed at some stations but its origin cannot be located

p to s converted wave observations at long valley caldera we report observations of p to s converted teleseismic body waves recorded with seismic stations located on the resurgent dome of long valley caldera we observe strong conversions occurring at boundaries that could be the tops of small magma bodies at depths of 4 9 kilometers beneath the resurgent dome this technique could prove to be an extremely powerful tool in the search for magma bodies for geothermal energy development our results from a two month deployment of triggered digital teleseismic recorders are discussed

an idealized modeling study of nocturnal cooling processes inside a small enclosed basin 1 the advanced regional prediction system is utilized to examine the evolution of the nocturnal boundary layer observed within arizona s meteor crater a small enclosed basin on quiescent nights during the 2006 meteor crater experiment field campaign two aspects of the observed basin atmosphere are investigated a quasi steady state three layer temperature structure including an isothermal layer away from the basin floor and the intrusion of a regional scale cold air drainage flow into the basin in general the two dimensional numerical simulations are able to reproduce the salient features of the nocturnal boundary layer inside meteor crater a combination of increasingly cold air intruding into the basin and pooling near the basin floor and compensating adiabatic ascent yield an isothermal layer over a large depth of the basin atmosphere a series of experiments are then conducted in order to examine the sensitivity of basin thermal structure to upstream terrain slope basin width and the presence of a rim surrounding the basin in the case of a large basin of o 10 km in diameter the cold air intrusion process remains but the larger basin volume yields greater dilution of the cold air intruding into the basin and a weak inversion develops inside the basin away from the floor in the case of a small basin with the same dimensions as meteor crater but with flat upstream terrain the influence of the surrounding terrain on basin cooling is negligible last the presence of a rim surrounding the basin is found to not be necessary for isothermal layer development

a gravity model of the crust beneath the tertiary piemonte basin northwestern italy abstract a gravity model of a crustal section crossing the tertiary piemonte basin from north to south is presented it was constructed by combining geological data and the results of the application of several geophysical methods with particular reference to the seismic findings a model is proposed for the morphology of the deep crust crust mantle transition identified by the wide angle reflection seismic data from the european geotraverse egt project and its geological consequences are discussed the existence of substantial displacements at the crust mantle boundary is stressed they do not appear to be directly related to superficial structures but underscore the wedging of the ligurian mantle on the insubrian crust compared with the observed bouguer gravity field gravity modelling of the section has supplied a calculated anomaly with a persistent short wavelength negative residual anomaly curve in the area of the asti basin it is suggested that this anomaly is due to a wedge of sedimentary rocks within the crust the wedge consists of both apennine and padane units and is located along a major structural boundary where metamorphic crust and tertiary sediments belonging to the alpine domain overthrust apennine and padane units during the tertiary

quasi steady katabatic winds on slopes in wide valleys hydraulic theory and observations theoretical and field observational studies on mean velocity and temperature fields of quasi steady nocturnal downslope katabatic flows on sloping surfaces are reported for the case of very wide valleys in the presence of weak synoptic winds because of the lateral constraints on the flow coriolis effects are considered negligible the layer averaged equations of manins and sawford were used for the analysis it is shown that i in the absence of significant turbulent entrainment into the current i e at large richardson numbers ri h cos u 2 the downslope flow velocity u is related to the slope length lh slope angle and the buoyancy jump between the current and the background atmosphere a su u lh sin 1 2 where u is a constant and h is the flow depth ii on very long slopes h is proportional to lh tan 1 2 and iii under highly stable conditions i e ri 1 the katabatic flow exhibits pulsations with period t0 2 n sin where n is the buoyancy frequency of the background atmosphere these predictions are verified principally using observations made during the vertical transport and mixing experiment vtmx conducted in salt lake city utah in october 2000 by assuming the flow follows a straight line trajectory to the nearest ridgeline a good agreement was found between the predictions and observations over appropriate richardson number ranges for ri 1 5 u 0 2 although u was a decreasing function of ri at lesser stabilities oscillations with period t0 are simply alongslope critical internal wave oscillations with a slope normal wavenumber which are liable for degeneration into turbulence during their reflection these critical internal waves may be responsible at least partly for weak sustained turbulence often observed in complex terrain nocturnal boundary layer flows

crustal structure beneath long valley caldera from modeling of teleseismic p wave polarizations and ps converted waves in this study the authors present new constraints on the nature of the low velocity zone beneath long valley caldera based on the measured propagation directions of teleseismic p waves and on modeling of p to s converted waves the low velocity body is a large asymmetrical volume which deepens to the east extending from depths of 7 to 30 km it contains lower velocities than originally proposed by earlier teleseismic studies in particular there is a tabular feature between 7 and 11 km depth that has a reduction in velocity of about 30 these low velocities imply a much greater percentage of melt in the crust beneath long valley caldera than previously estimated array analysis of large delayed arrivals identifies them to be ps converted waves from the shoulders and roof of this tabular zone these conversions bound the depth to the magma chamber roof to be within about 10 km of the surface these results are consistent with elements from several other studies and the authors present an integrated and improved model of crustal structure at long valley the concordance of the deeper low velocity zones with regional structural trends implies that the shallow low velocity feature is a cupola on topmore of an asymmetric diapiric ridge rising up from the migmatized lower crust of the basin and range the authors present two contrasting interpretations of the geometry of low velocity zones in the crust one implies a time invariant magma chamber and conduit system for long valley caldera the other implies an evolution of that system from a simple vertical regime to its current asymmetrical geometry 37 refs 19 figs 1 tab less

the evolution and sensitivity of katabatic flow dynamics to external influences through the evening transition data collected over an arid shallow slope 2 4 during the mountain terrain atmospheric modeling and observations materhorn program are used to study the katabatic structure and onset of katabatic flow through the evening transition an unprecedented suite of instrumentation including a transect of five turbulence towers with 29 sonic anemometers is used for the investigation fifteen transition periods with well defined katabatic flow and relatively little synoptic forcing are used in the study the katabatic onset jet velocity and jet height all show a large degree of interdiurnal and intersite variance the slope aligned budgets of momentum and potential temperature are used to define time scales that describe the evolution of the katabatic flow composite wind velocity time series are used to show that 30 min elapses from the time when the katabatic flow initializes at 0 5 m to the point of initialization at 20 m a simple katabatic model utilizing surface energy budget modeling is developed and used to model the interdiurnal katabatic variance finally uni and multi variate statistical analysis are used to diagnose the influence of specific external variables valley wind speed turbulence structure soil moisture and shadow front speed are all found to influence the katabatic dynamics to varying degrees

observations of ambient noise and signal coherency on the island of hawaii for teleseismic studies abstract ambient seismic noise conditions at several sites on the island of hawaii have been studied by analyzing noise power spectral density psd and signal to noise ratio snr of teleseisms broadband digital waveform data used in this study were collected during project aloha direct comparison of noise psd and snr of teleseisms simultaneously recorded at stations on hawaii and at station kip on oahu indicates that the stations on hawaii are quieter than station kip on oahu in the frequency band of 0 1 to 1 hz suggesting that the island of hawaii can provide better noise conditions than station kip our interpretation of this observation is that the area and volume of hawaii are much larger than those of oahu and distances to the coast for the stations on hawaii are larger than that for station kip on oahu stronger attenuation and relatively low coherency for teleseismic signals on hawaii in frequencies of 0 4 to 1 2 hz are attributed to the presence of partial melt in the upper mantle teleseismic signal coherency is very low at frequencies above 2 hz for a small array with a radius about 2 km the relatively high coherency of the tangential component is strongly indicative of severe scattering effects caused by the heterogeneity in structure of the active volcanic area

optimal control of katabatic flows within canopies what slope angle favours the development of katabatic flow is still an open question some studies have clarified that katabatic winds are stronger on steep slopes while others have demonstrated that katabatic winds are stronger on gentle slopes here we explore the control mechanisms of katabatic flow using a simplified theoretical model in an attempt to clarify the causes of the paradoxical findings our results indicate that optimal conditions for katabatic flows within canopies are synergistically controlled by terrain angle canopy structure and thermal condition through a simple equation where is terrain slope lc 1 cda is canopy length scale cd is drag coefficient a is leaf area density vt rc is a thermal factor rc is a cooling rate is ambient lapse rate and b is a constant this theoretical prediction implies that gentle slopes are optimal for katabatic flow developments in stably stratified air while steep slopes are optimal in weak or near neutral stratification canopy effect is significant in the control of katabatic flows only on gentle slopes copyright 2012 royal meteorological society

tomography of the source area of the 1995 kobe earthquake evidence for fluids at the hypocenter seismic tomography revealed a low seismic velocity 5 and high poisson s ratio 6 anomaly covering about 300 square kilometers at the hypocenter of the 17 january 1995 magnitude 7 2 kobe earthquake in japan this anomaly may be due to an overpressurized fluid filled fractured rock matrix that contributed to the initiation of the kobe earthquake

p sv conversions at a shallow boundary beneath campi flegrei caldera italy evidence for the magma chamber seismograms from an active seismic experiment carried out at campi flegrei caldera near naples italy show a large amplitude 5v polarized shear wave following by less than 1 5 s p waves reflected at wide angle from a deep crustal interface early arriving sv polarized waves with the same delay to direct p waves are also observed in seismograms from a regional 280 km deep magnitude 5 1 earthquake such short delays of s to p waves are consistent with a p sv conversion on transmission occurring at a shallow boundary beneath the receivers the large amplitude of the converted sv phase along with that the p waves are near vertical requires a boundary separating a very low rigidity layer from the upper caldera fill the converted phases are interpreted as a seismic marker of a magma chamber the top of this magma chamber is located slightly deeper than the deepest earthquakes observed during the 1982 1984 unrest of campi flegrei

seismic evidence for an ancient rift beneath the cumberland plateau tennessee a detailed analysis of broadband teleseismic p waveforms broadband receiver functions developed from teleseismic p waveforms recorded on the midperiod passband of regional seismic test network station rscp are inverted for vertical velocity structure beneath the cumberland plateau tennessee the detailed broadband receiver functions are obtained by stacking source equalizd horizontal components of teleseismic p waveforms the resulting receiver functions are most sensitive to the shear velocity structure near the station a time domain inversion routine utilizes the radial receiver function to determine this structure assuming a crustal model parameterized by many thin flat lying homogeneous layers lateral changes in structure are identified by examining azimuthal variations in the vertical structure the results reveal significant rapid lateral changes in the midcrustal structure beneath the station that are interpreted in relation to the origin of the east continent gravity high located northeast of rscp the results from events arriving from the northeast show a high velocity midcrustal layer not present in results from the southeast azimuth this velocity structure can be shown to support the idea that this feature is part of a keweenawan rift system another interesting feature of the derived velocity models is the indication that the crust mantle boundary beneath the cumberland plateau is a thick probably laminated transition zonemore between the depths of 40 and 55 km a result consistent with interpretations of early refraction work in the area less

tertiary structural relationships between alps and apennines the critical torino hill and monferrato area northwestern italy the relationship between the alpine and apenninic orogenic systems is concealed at the surface by tertiary sediments of two main tectono stratigraphic units the alpine related torino hill domain and the apennines related monferrato domain mapping and structural analyses carried out in the area behind the mio pliocene apenninic padane thrust front allow comparison of the kinematic history of the torino hill and monferrato domains these are separate by the transpressive tlio freddo deformation zone rfdz interpreted here as the superficial expression of a crustal discontinuity along which the alpine metamorphic basement overrode the apenninic ligurian nappes during the palaeogene the western monferrato structural setting is the result of i late oligocene burdigalian transpressive tectonics due to lateral displacement between the alps related and the apennines related domains and ii compressive post messinian tectonics related to northward transport along the main padane thrust front post messinian tectonic events affected also the nw vergent asymmetrical torino hill anticline

can a simple dynamical system describe the interplay between drag and buoyancy in terrain induced canopy flows abstractunder nonneutral stratification and in the presence of topography the dynamics of turbulent flow within a canopy is not yet completely understood this has among other consequences serio

location and configuration of magma bodies beneath long valley california determined from anomalous earthquake signals recordings of 281 small earthquakes which occurred recently near the southern edge of long valley caldera at depths from 1 to 15 km are used to map the subsurface geometry of shear wave attenuating bodies in the caldera signatures of these events recorded northwest north northeast and east of long valley with ray paths through the caldera are often anomalous in that s wave arrivals have very low amplitudes and high frequency p and s wave energy is missing for the same station event combinations the volcanic and geothermal history of the region suggests that ray paths for these anomalous signals have passed through magma which absorbed much of the s wave energy and also attenuated the higher frequencies with over 1200 normal and anomalous ray paths through the caldera we have located two apparently massive magma bodies in the central and northwest caldera as well as two more dispersed magma areas in the southern caldera and beneath crowley lake the central magma body extends from 4 5 to at least 13 km beneath the surface and the northwest body is as shallow as 5 5 km these two magma bodies are probably connected below about 8 km secondary arrivals seen on select seismograms are tentatively interpreted as reverberations inside the central magma chamber and are consistent with the interpreted lateral extent of the magma the northwest and central magma bodies lie beneath the northwest and southeast corners of the caldera s resurgent dome and probably connect beneath the dome s center also the shallower parts of these magma bodies and the southern anomalous area lie beneath the surface expression of the medial graben faults suggesting that structural features seen at the surface of the valley may be related to magma location at depth