annual cycle and depth penetration of wind generated near inertial internal waves at ocean station papa in the northeast pacific abstractthe downward propagation of near inertial internal waves following winter storms is examined in the context of a 2 yr record of velocity in the upper 800 m at ocean station papa the long time series allow accurate estimation of wave frequency whereas the continuous data in depth allow separation into upward and downward propagating components near inertial kinetic energy kein dominates the record at all measured depths energy in downgoing motions exceeds that of upward propagating motions by factors of 3 7 whereas kein is elevated by a factor of 3 5 in winter relative to summer the two successive winters are qualitatively similar but show important differences in timing and depth penetration energy is seen radiating downward in a finite number of wave groups which are tagged and catalogued to determine the vertical group velocity cgz which has a mean of about 1 5 10 4 m s 1 13 m day 1 case studies of three of these are presented in detail downward energy flux is estimated as cgz

controls on structural styles along the deformation front of the subandean zone of southern bolivia abstract the subandean zone of southern bolivia is a typical thin skinned fold and thrust belt with remarkable regularity in the geometry of the structures however when the structural geometry and evolution are analyzed in detail it is verified that there are many deviations from such regularity in this paper special emphasis has been placed on analyzing those processes that could explain the along strike variations in structural styles of the deformation front particularly the role that played the upper detachment level in the development of the different structural styles observed along the deformation front is analyzed herein this analysis is focused on the development of overpressures which may have been essential for the activation of the detachment level in the devonian shales of the los monos formation to do this we made a series of 1d petroleum system models at different locations along the deformation front this analysis allowed to model primary gas generation and secondary cracking processes that are related to overpressure occurrence and therefore to the efficiency of the upper detachment level the models suggest a close relationship between thermal evolution of the foreland basin and generation of gas with different structural styles observed at the deformation front thus it was possible to divide the deformation front of the southern subandean zone into two distinct segments in the northern segment where models suggest that gas generation and overpressures of the los monos formation would be well developed the existence of composite roof duplexes is verified on the other hand where the models suggest that generation of gas in the los monos formation would be limited the upper detachment level is not involved in the deformation and the existence of fault bend fold structures is verified

redistribution of energy available for ocean mixing by long range propagation of internal waves ocean mixing which affects pollutant dispersal marine productivity and global climate1 largely results from the breaking of internal gravity waves disturbances propagating along the ocean s internal stratification a global map of internal wave dissipation would be useful in improving climate models but would require knowledge of the sources of internal gravity waves and their propagation towards this goal i present here computations of horizontal internal wave propagation from 60 historical moorings and relate them to the source terms of internal waves as computed previously2 3 analysis of the two most energetic frequency ranges near inertial frequencies and semidiurnal tidal frequencies reveals that the fluxes in both frequency bands are of the order of 1 kw m 1 that is 15 50 of the energy input and are directed away from their respective source regions however the energy flux due to near inertial waves is stronger in winter whereas the tidal fluxes are uniform throughout the year both varieties of internal waves can thus significantly affect the space time distribution of energy available for global mixing

target oriented wide patch 3 d seismic yields trap definition and exploration success in the sub andean thrust belt devonian gas play tarija basin argentina the sub andean thrust belt of the tarija basin in south america is undergoing an exploration boom due to interest in the emerging deep fractured devonian gas play trap types involve hanging wall anticlines which formed due to continued thrusting the structures were formed by a rigid beam type response to compression with a major thrust fault detachment in the deep kirusillas shale a second roof detachment thrust fault system is often responsible for additional vertical deformation of younger strata and for west to east displacement with respect to deep devonian traps the interplay between these two detachments makes it difficult to predict the geometries of deep devonian traps acambuco an area of about 300 000 acres in the extreme northwest of argentina along the bolivian border is operated by the ute acambuco partnership which includes pan american energy operator ypf sa oil gas a shell capsa subsidiary and apco nw acambuco is part of the southern extension of the bolivian sub andean trend in the tarija basin it spans two mountain ranges the sierra de aguarague in the eastern part of the block and the sierra de san antonio in the west both trends include fields in the multi tcf range figure 1 figure 1 the acambuco area in the extreme nw of argentina this satellite image spot with landsat in pseudo color shows that the area spans two major structural trends note the surface expression of major structures in the area exploration challenges associated with prospects in the fairway involve defining traps and assessing reservoir quality these risks can be addressed adequately through the use of integrated 3 d seismic interpretation with horizontal drilling and multilateral completions understanding structural style is paramount to seismic interpretation in the sub andean thrust belt the foothills form a series of laterally extensive folded and thrusted mountain ranges trending nne spacing between the mountain

high level surfaces plateau uplift and foreland development bolivian central andes newly dated tertiary strata in the bolivian central andean plateau and synthesis of the tertiary record in the adjacent subandean fold thrust belt constrain the age of deformation in both regions age of deformation within the plateau is determined by dated crosscutting relations associated with a regionally extensive high level surface known as the san juan del oro surface new 40 ar 39 ar dates on undeformed strata above the high level surface preclude significant upper crustal shortening within the eastern cordillera after 10 ma tertiary strata within the adjacent subandean region demonstrate that formation of the fold thrust belt occurred after 10 ma on the basis of these data we propose a two stage model of late cenozoic andean growth that links plateau uplift to the development of the fold thrust belt in the first stage early plateau uplift occurred in response to widespread compressional deformation of the plateau eastern cordillera and altiplano during the second stage beginning after 10 ma upper crustal deformation within the plateau terminated and the subandean fold thrust belt developed crustal scale eastward thrusting along the eastern margin of the eastern cordillera drove subandean folding and thrusting the eastern cordillera served as the bulldozer for the deforming subandean wedge

the energy flux from the wind to near inertial motions in the surface mixed layer abstract time series of wind stress computed from long term meteorological buoy data off north america are used to examine the forcing of surface inertial currents by the wind a simple damped slab model of the mixed layer is used to compute h the average flux of energy from the wind to mixed layer inertial currents in a mixed layer of fixed depth h the forcing of mixed layer inertial motions is highly intermittent most of the forcing occurs during the winter months with a few dozen events accounting for typically over half the total energy flux major forcing events are usually associated with translating cold fronts or small lows with scales of about 100 km the larger synoptic scale features have little energy at the inertial frequency and thus result in only weak forcing of inertial currents a strong seasonal signal exists in the inertial forcing at ows p 50 n 145 w 50 m is largest from october to february and is a factor of 12 above the june and july values if seasonally varying

robust smooth magnetotelluric transfer functions jimmy c larsen randall l mackie 2 adele man e l l a adolfo fiordelisi4 and shirley rieven2 pacific marine environmental laboratory national oceanic and atmospheric administration 7600 sand point way ne seattle wa 981 15 0070 usa wassachusetts institute of technology 42 carleton street cambridge m a 02142 usa cnr international institute for geothermal research piazza soljerino 2 pisa 56126 italy enel esplorazione mineraria via andrea pisano 120 pisa 56122 italy

spontaneous generation of near inertial waves by the kuroshio front abstractwhile near inertial waves are known to be generated by atmospheric storms recent observations in the kuroshio front find intense near inertial internal wave shear along sloping isopycnals even during calm weather recent literature suggests that spontaneous generation of near inertial waves by frontal instabilities could represent a major sink for the subinertial quasigeostrophic circulation an unforced three dimensional 1 km resolution model initialized with the observed cross kuroshio structure is used to explore this mechanism after several weeks the model exhibits growth of 10 100 km scale frontal meanders accompanied by o 10 mw m 2 spontaneous generation of near inertial waves associated with readjustment of submesoscale fronts forced out of balance by mesoscale confluent flows these waves have properties resembling those in the observations however they are reabsorbed into the model kuroshio front with no more than 15 dissipating or radiating away thus spontaneous generation o

improved global maps and 54 year history of wind work on ocean inertial motions 1 the global distribution and 54 year time dependence of the energy flux from the wind to near inertial motions is computed by driving a slab mixed layer model with ncep ncar reanalysis winds improving upon previous estimates alford 2001 watanabe and hibiya 2002 the slab model is solved spectrally with frequency dependent damping the resulting solutions are more physically sensible than the previous and more skillful at high latitudes where the inertial frequency approaches the 4 daily sampling of the reanalysis winds this enables alford s calculation whose domain was limited to 50 to be extended to the poles the high latitude reliability is demonstrated by direct comparison with a high resolution regional model remo in the ne atlantic the total power input 0 47 tw has increased by 25 since 1948 paralleling observed increases in extratropical cyclone frequency and intensity if believable the trend may have important consequences for modulation of the meridional overturning circulation

andean age structure of eastern cordillera province of la paz bolivia a moho root beneath the bolivian andes 40 km deep is consistent with 230 km of overlap of neogene age on a single trenchward dipping transcrustal thrust fault with 10 of finite ramp cutoff main andean thrust mat only 10 of the andean crustal volume is ascribable to magmatic addition the mat is located within south american crust of full thickness it intersects the basement top 450 km inland from the neogene crustal margin it is not a collision suture as shown by persistent pre neogene facies continuity thrusting is not accompanied by terrane accretion the present bilaterally symmetrical thrust belt responds to elastic line loading and to coulomb rheology in the hanging wall of the mat a deep high stress wedge base builds a steep critical slope in the footwall the foredeep response is fast subcritical growth by progradation and blind thrusting on a low stress decollement interaction is maintained by out of sequence renewal of movement on the mat

restratification of the surface mixed layer with submesoscale lateral density gradients diagnosing the importance of the horizontal dimension abstract a depth cycling towed conductivity temperature depth ctd and vessel mounted acoustic doppler current profiler adcp were used to obtain four dimensional measurements of the restratification of the surface mixed layer sml at a submesoscale lateral density gradient near the subtropical front with the objective of studying the role of horizontal processes in restratification the thermohaline and velocity fields were monitored for 33 h by 16 small scale 15 km2 surveys centered on a drogued float daytime warming by insolation caused a unidirectional displacement of the initially vertical isopycnals toward increasing density across the entire sml 50 m vertical scale solar insolation accounted for 60 of observed restratification but over 10 m scales the percentage decreased with depth from 80 at 25 35 m to 25 at 55 65 m below 35 m stratification was enhanced by the vertically sheared horizontal advection of the lateral density gradient due to a near inertial wave of 100 m vertica

processing of seismic data from overthrust areas in latin america overthrust areas represent some of the last true frontiers in petroleum exploration today and the industry is increasingly looking toward them for new discoveries chevron has had significant success in overthrust exploration over the past two decades as a result of major discoveries in papua new guinea and the wyoming thrust belt however seismic data recorded in some overthrust areas is disappointingly poor challenges such as rough topography complex subsurface structure presence of high velocity carbonates and or paleozoic rocks at the surface back scattered energy and severe migration wavefronting continue to lower data quality and reduce interpretability lack of well control and velocity information also reduces reliability of depth estimations and migrated images these difficulties have tended to increase technical risk and combined with the high cost of acquisition have lowered the expected value of overthrust plays the history of exploration in thrust belts has shown the critical impor

subandean thrust and fold belt of northwestern argentina geometry and timing of the andean evolution the subandean ranges of northwestern argentina are an active thin skinned fold and thrust belt the main detachment level in silurian shales dips 2 3w and all the major east verging faults detach from it important intermediate detachment levels in the devonian shales generate lift off structures and the decoupling of the lower and upper structural levels the subandean thrust belt has a minimum shortening of about 60 km 36 at about 2240 latitude the deformation started at about 8 5 9 ma with the uplift of the el pescado range and the formation of an important back thrust at the cinco picachos range fault generation gets young to the east the pintascayo range uplift started at 7 6 ma while the baja orn range uplift began at about 6 9 ma these two ranges continued growing simultaneously until at least 4 7 ma at san antonio range fault movement began at approximately 4 4 ma and the aguarage uplift started at about 2 7 ma an important stage dominated by out of sequence movements spans from about 4 5 ma to present for both proposed models of shortening the quaternary rates of shortening between 8 and 11 mm yr coincide well with global positioning system results from the area the hydrocarbon generation and migration is contemporaneous with the deformation enhancing the possibilities of hydrocarbon entrapment in the area

the modern foreland basin system adjacent to the central andes regional variations in sediment thickness internal structures average elevation and bouguer gravity define a four component foreland basin system adjacent to the central andes in the most proximal part of the foreland basin system the eastern subandean zone and westernmost chaco plain 1 3 km of cenozoic deposits overlies active folds and thrusts of the frontal andean orogenic wedge these wedge top deposits pass cratonward into a foredeep depozone containing a 3 4 km thick sedimentary prism that tapers toward and locally pinches out against a broad wavelength forebulge in the central eastern chaco plain the forebulge is underlain by precambrian mesozoic rocks and is largely covered by a thin veneer of quaternary alluvium east of the forebulge a thin 0 5 km saucer shaped accumulation of sediment beneath the pantanal wetland represents a back bulge depozone ancient counterparts of these four depozones can be identified in the central andes suggesting that modern basin architecture is the result of continuous eastward migration of the coupled orogenic wedge and foreland basin system since the late cretaceous paleocene

the kinematic history of the central andean fold thrust belt bolivia implications for building a high plateau this paper presents a model for the kinematic evolution of the central andean plateau based on balanced cross sections across the bolivian andes the proposed model links the formation of the andean plateau to the development of the andean fold thrust belt through the creation and propagation of two large basement mega thrusts support for large basement involved thrust sheets is found in significant steps in both the topography and the exposed structural elevation of the andean fold thrust belt the structurally highest basement thrust raised folds and faults in predominantly lower paleozoic rocks of the eastern cordillera with respect to tertiary rocks in the broad internally drained basin of the altiplano to the west and east verging folds and faults in upper paleozoic rocks of the interandean zone to the east the interandean zone was in turn raised both structurally and topographically with respect to the frontal folds and faults of the fold thrust belt the subandean zone by a second structurally lower basement thrust sheet thus these two megathrusts divide the andean fold thrust belt into four areas of markedly different structural elevations the eastern cordillera can be further subdivided into two zones of west and east vergent folds and thrusts shortening accommodated by the fold thrust belt can be divided among these tectono structural zones and linked to shortening accommodated by the inferred basement megathrusts the proposed kinematic model suggests that the eastward propagation of the structurally highest basement thrust fed 105 km of slip into the eastern cordillera along east vergent and west vergent faults this structure also fed 90 km of eastward slip into the interandean zone the initiation and eastward propagation of a lower basement thrust structurally elevated the interandean zone with respect to the foreland while feeding 65 km of slip into the subandean zone out of sequence basement thrusting to the west is proposed to have elevated the western edge of the plateau and accommodated 40 km of shortening within the altiplano total cumulative shortening within the cover rocks of the andean fold thrust belt 300 330 km can be balanced by an equivalent amount of shortening along two basement megathrusts to the first order the eastern margin of the central andean plateau defined by the 3 km topographic contour is contiguous with the leading edge of the upper basement megathrust this relationship between the basement highs and the physiographic boundaries of the andean plateau suggests that extensive megathrust sheets involving strong rocks such as crystalline basement or quartzite play an important role in the formation of the central andean plateau and a similar link between megathrust sheets and plateaus may be found in other orogens

enhanced vertical propagation of storm induced near inertial energy in an eddying ocean channel model the interaction between inertial oscillations generated by a storm and a mesoscale eddy field is studied using a southern ocean channel model it is shown that the leakage of near inertial energy out of the surface layer is strongly enhanced by the presence of the eddies with the anticyclonic eddies acting as a conduit to the deep ocean given the ubiquity of the atmospheric storm tracks a source of near inertial energy for the ocean and regions of strong ocean mesoscale variability we argue that this effect could be important for understanding pathways by which near inertial energy enters the ocean and is ultimately available for mixing

ocean currents evident in satellite wind data satellite mounted radar scatterometers designed to quantify surface winds over the ocean actually measure the relative motion between the air and the ocean surface estimates of the wind stress from conventional surface wind measurements are usually derived neglecting ocean currents however when the relative motion is used the differences in the estimated stress can be as large as 50 near the equator and may even reverse sign during an el nino this assertion is supported by the strong relationship between the surface currents measured by the tropical atmosphere ocean tao array in the pacific ocean and the differences between the winds estimated from scatterometer data and those measured by tao anemometers the fact that the scatterometer measures relative motion and not wind alone makes scatterometer derived stress a more accurate representation of the boundary condition needed for both atmospheric and oceanic models than stress fields derived neglecting ocean currents

observations of near inertial internal gravity waves radiating from a frontal jet abstractshipboard adcp and towed ctd measurements are presented of a near inertial internal gravity wave radiating away from a zonal jet associated with the subtropical front in the north pacific three dimensional spatial surveys indicate persistent alternating shear layers sloping downward and equatorward from the front as a result depth integrated ageostrophic shear increases sharply equatorward of the front the layers have a vertical wavelength of about 250 m and a slope consistent with a wave of frequency 1 01f they extend at least 100 km south of the front time series confirm that the shear is associated with a downward propagating near inertial wave with frequency within 20 of f a slab mixed layer model forced with shipboard and ncep reanalysis winds suggests that wind forcing was too weak to generate the wave likewise trapping of the near inertial motions at the low vorticity edge of the front can be ruled out because of the extension of the features well south of it instead the authors

the impact of oceanic near inertial waves on climate abstractthe community climate system model version 4 ccsm4 is used to assess the climate impact of wind generated near inertial waves niws even with high frequency coupling ccsm4 underestimates the strength of niws so that a parameterization for niws is developed and included into ccsm4 numerous assumptions enter this parameterization the core of which is that the niw velocity signal is detected during the model integration and amplified in the shear computation of the ocean surface boundary layer module it is found that niws deepen the ocean mixed layer by up to 30 but they contribute little to the ventilation and mixing of the ocean below the thermocline however the deepening of the tropical mixed layer by niws leads to a change in tropical sea surface temperature and precipitation atmospheric teleconnections then change the global sea level pressure fields so that the midlatitude westerlies become weaker unfortunately the magnitude of the real air sea flux of niw energy is poorly con

on the behavior of internal waves in the wakes of storms abstract the rossby adjustment process in the wake of a storm is studied with a view to finding within the context of linear theory how wave dispersion in both the vertical and meridional directions spreads energy which is initially confined entirely to the mixed layer comparisons are made between three cases 1 a periodic storm on the f plane where dispersion is purely vertical 2 a bounded storm on the f plane and 3 a bounded storm centered 2700 km from the equator on an equatorial beta plane particular attention is paid to the initial rate of loss of energy from the mixed layer and some simple formulas which work very well in the cases studied are derived these show that the rate of loss goes up when the mixed layer depth is increased and also that the rate scales as the square of the wavenumber values of the rates are sufficient to provide a major source of energy for internal waves below the mixed layer the often observed tendency for phase lines to propagate upward is found in all case

a global perspective on langmuir turbulence in the ocean surface boundary layer the turbulent mixing in thin ocean surface boundary layers osbl which occupy the upper 100 m or so of the ocean control the exchange of heat and trace gases between the atmosphere and ocean here we show that current parameterizations of this turbulent mixing lead to systematic and substantial errors in the depth of the osbl in global climate models which then leads to biases in sea surface temperature one reason we argue is that current parameterizations are missing key surface wave processes that force langmuir turbulence that deepens the osbl more rapidly than steady wind forcing scaling arguments are presented to identify two dimensionless parameters that measure the importance of wave forcing against wind forcing and against buoyancy forcing a global perspective on the occurrence of wave forced turbulence is developed using re analysis data to compute these parameters globally the diagnostic study developed here suggests that turbulent energy available for mixing the osbl is under estimated without forcing by surface waves wave forcing and hence langmuir turbulence could be important over wide areas of the ocean and in all seasons in the southern ocean we conclude that surface wave forced langmuir turbulence is an important process in the osbl that requires parameterization citation belcher s e et al 2012 a global perspective on langmuir turbulence in the ocean surface boundary layer geophys res lett 39 l18605 doi 10 1029 2012gl052932

mixing in the transition layer during two storm events abstract upper ocean dynamics analyzed from mooring array observations are contrasted between two storms of comparable magnitude particular emphasis is put on the role of the transition layer the strongly stratified layer between the well mixed upper layer and the deeper more weakly stratified region the midlatitude autumn storms occurred within 20 days of each other and were measured at five moorings in the first storm the mixed layer follows a classical slab layer response with a steady deepening during the course of the storm and little mixing of the thermocline beneath in the second storm rather than deepening the mixed layer shoals while intense near inertial waves are resonantly excited within the mixed layer these create a large shear throughout the transition layer generating turbulence that broadens the transition layer details of the space time structure of the frequencies in both short waves and near inertial waves are presented small scale waves are excited within the transition

3d magnetotelluric modelling including surface topography an edge finite element method has been applied to compute magnetotelluric mt responses to three dimensional 3d earth topography the finite element algorithm uses a single edge shape function at each edge of hexahedral elements guaranteeing the continuity of the tangential electric field while conserving the continuity of magnetic flux at boundaries we solve the resulting system of equations using the biconjugate gradient method with a jacobian preconditioner the solution gives electric fields parallel to the slope of a surface relief that is often encountered in mt surveys the algorithm is successfully verified by comparison with other numerical solutions for a 3d 2 model for comparison of modelling methods for em induction and a ridge model we use a 3d trapezoidal hill model to investigate 3d topographic effects which are caused mainly by galvanic effects not only in the zxy mode but also in the zyx mode if a 3d topography were approximated by a two dimensional topography therefore errors occurring in the transverse electric mode would be more serious than those in the transverse magnetic mode

lower bound on the amount of crustal shortening in the central bolivian andes balanced cross sections across the cordillera oriental and subandean zone of the central bolivian andes indicate that crustal shortening probably has played the dominant role in orogeny in this convergent margin setting a minimum amount of shortening 210 km is documented which can account for two thirds of the present day crustal cross sectional area along a transect spanning the entire mountain range substantial crustal shortening may also require loss of the lower lithosphere to the asthenosphere a large minimum amount of crustal shortening in the bolivian andes shows contrary to common assumptions about orogeny that 1 magmatic addition may be volumetrically less important in orogeny in andean type margins and 2 crustal shortening is not uniquely associated with continental or island arc collision

enhancing imaging of the sub andean foothills geology using magnetotellurics a case history of a 3d survey in southern bolivia abstract a magnetotelluric acquisition and modelling campaign comprising 400 full tensor soundings was carried out in the sub andean foothills in the area located south of santa cruz de la sierra bolivia the objective of the survey was to improve the imaging of the paleozoic section and provide insight to the overall structure of the devonian silurian complex the acquired data were inverted assuming both two dimensional and three dimensional dimensionality of the subsurface structure adopting a multi step iterative workflow which began applying unconstrained inversion and introduced increasing constraints determined at each following step based on the interpretation of the latest inversion results the geological interpretation of the final inversion results allowed to better image the expected complexity in the structures particularly highlighting several different levels of detachment mainly in the area of kirusillas formation furthermore an oblique sense was identified of the main tendency of n s deformation related to a dextral transgressional movement that generates discrete dislocations at a length scale of the order of a few kilometres

basement involved blind thrusting in the eastern cordillera oriental southern bolivia evidence from cross sectional balancing gravimetric and magnetotelluric data abstract a neogene to recent thrust belt forms the subandean ranges and cordillera oriental along the eastern slope of the central andes in bolivia over much of its length there is an area of intermediate topographic height and structural level between the subandean zone and the cordillera oriental proper cross sectional balancing suggests that in southern bolivia the basal detachment of this tightly folded zone links up with a blind thrust that dips westward beneath the high standing eastern margin of the cordillera oriental and rides piggy back on a large buried thrust sheet which forms the backstop for the thin skinned subandean belt magnetotelluric and gravimetric data indicate that this thrust sheet is made up of basement rocks probably including intrusives and higher grade metamorphics such blind basement thrusts in a relatively external position may characterize much of the eastern andean thrust belt and their geometry is possibly related to preexisting structural patterns linked to the configuration of early palaeozoic basins and their margins

prescriptions for heat flux and entrainment rates in the upper ocean during convection abstract a detailed investigation of the upper ocean during convection reveals the vertical structure of potential temperature to be steady in time and the current shear to vanish in the bulk of the mixed layer these imply that a slab type model may be an adequate representation of the convective ocean boundary layer obl in contrast when convection is not the dominant forcing mechanism the obl is stratified and can support a significant current shear this indicates the inadequacy of slab models for the nonconvective obl two independent estimates of the vertical heat flux profile in the convective obl were made the first estimate results from heat conservation and the steadiness of the vertical structure of potential temperature the second estimate is based on the turbulent kinetic energy tke balance and the vertical profiles of tke dissipation rate the estimates are consistent and suggest that the nondimensional vertical heat flux due to turbulence has a linear depth dependence o

sustained full water column observations of internal waves and mixing near mendocino escarpment abstract the relative strength and spatiotemporal structure of near inertial waves niw and internal tides it are examined in the context of recent moored observations made 19 km south of mendocino escarpment an abrupt ridge step feature in the eastern pacific in addition to strong internal tide generation steps and ridges give rise to the possibility of shadowing wherein near inertial energy is prevented from reaching depths beneath a characteristic intersecting the ridge top a combination of two moored profilers and a long range acoustic doppler current profiler adcp yielded velocity and shear measurements from 100 to 3640 m 60 m above bottom and isopycnal depth strain and overturn inferred turbulence dissipation rate from 1000 to 3640 m sampling intervals 20 min in the upper 1000 m and 1 5 h below that were fast enough to minimize aliasing of higher frequency internal wave motions the 67 day long record is easily sufficient to isolate niw and it via bandpass filtering and to capture

the inertial chimney the near inertial energy drainage from the ocean surface to the deep layer a three dimensional primitive equation numerical model is used to study the behavior of near inertial waves generated by surface wind stress on an plane the model is fixed depth with a rigid lid on the surface and is horizontally periodic this study shows the behaviors of the wind generated near inertial waves for four different eddies 1 a subtropical cold core eddy 2 a subtropical warm core eddy 3 a california subsurface warm core eddy and 4 the gulf stream warm core ring the mean secondary circulation generated by the wind eddy interaction has magnitude to comparable to that of the ekman current and its characteristics are determined by the relative angle between wind and current the propagation characteristics of near inertial waves are quite different depending upon the sign of the relative vorticity in a cyclonic eddy near inertial wave propagation is outward from the core of the eddy the propagation direction in an anticyclonic eddy is downward and toward the core vertically propagating waves inside the eddy are trapped above a critical layer and slowly dissipated by parameterized viscous effects the model shows that anticyclones efficiently drain near inertial energy from the surface to the deep layer below the thermocline

geometry and kinematic evolution of passive roof duplexes deduced from cross section balancing example from the foreland thrust system of the southern bolivian subandean zone the subandean zone of bolivia is a foreland fold and thrust belt which forms the eastern edge of the central andes mountains between 19 s and 22 s latitude the construction of five balanced cross sections shows that the n s trending subandean zone is characterized by the existence of passive roof duplexes these complex structures can be distinguished by the lithotectonic unit within which duplexing occurs the five balanced cross sections permit the geometric and kinematic analyses of these passive roof duplexes the sequential restorations of certain cross sections reveal a possible development of a piggy back sequence of three passive roof duplexes apparently these passive roof duplexes propagated toward the foreland from deeper and deeper lithotectonic units while a passive roof duplex was developing the sole thrust stuck and the major horizontal displacements were then transferred either to out of sequence thrusts or to a new sole thrust in a deeper detachment horizon therefore each passive roof duplex would correspond to the orogenic front of the andean range at one very particular time in the history of the subandean zone of southern bolivia from south to north the quantitative analysis by cross section balancing shows a transfer of displacement from the hinterland structures to the passive roof duplex that forms the present orogenic front available data do not permit us to explain completely this phenomenom

observations of the transition layer abstract the transition layer is the poorly understood interface between the stratified weakly turbulent interior and the strongly turbulent surface mixed layer the transition layer displays elevated thermohaline variance compared to the interior and maxima in current shear vertical stratification and potential vorticity a database of 91 916 km or 25 426 vertical profiles of temperature and salinity from seasoar a towed vehicle is used to define the transition layer thickness acoustic doppler current measurements are also used when available statistics of the transition layer thickness are compared for 232 straight seasoar sections which range in length from 65 to 1129 km with typical horizontal resolution of 4 km and vertical resolution of 8 m transition layer thicknesses are calculated in three groups from 1 vertical displacements of the mixed layer base and of interior isopycnals into the mixed layer 2 the depths below the mixed layer depth of peaks in shear stratification and potenti