eddy resolving observation of the north pacific subtropical mode water abstracthydrographic data obtained by high resolution shipboard observations and argo profiling floats have been analyzed to study the mesoscale structure and circulation of the north pacific subtropical mode water stmw the float data show that in the late winter of 2008 stmw having a temperature of approximately 18 8 17 7 and 16 6 c formed west of 140 e at 140 150 e and east of 150 e respectively in the recirculation gyre south of the kuroshio extension after spring the newly formed stmw gradually shift southward decreasing in thickness simultaneously the stmws of 16 6 and 17 7 c are gradually stirred and then mixed in terms of properties in late fall they seem to be integrated to form a single group of stmws having a temperature centered at 17 2 c such stmw circulation in 2008 is much more turbulent than that in 2006 which was investigated in a previous study the difference between the two years is attributed to the more variable state of the kuroshio extension in 2008 associate

atmospheric rotors and severe turbulence in a long deep valley abstractthe conceptual model of an atmospheric rotor is reexamined in the context of a valley using data from the terrain induced rotor experiment t rex conducted in 2006 in the southern sierra nevada and owens valley california all t rex cases with strong mountain wave activity have been investigated and four of them iops 1 4 6 and 13 are presented in detail their analysis reveals a rich variety of rotorlike turbulent flow structures that may form in the valley during periods of strong cross mountain winds typical flow scenarios in the valley include elevated turbulence zones downslope flow separation at a valley inversion turbulent interaction of in valley westerlies and along valley flows and highly transient mountain waves and rotors the scenarios can be related to different stages of the passage of midlatitude frontal systems across the region the observations from owens valley show that the elements of the classic rotor concept are modulated and at times almost completely offset

salt tectonics off northern israel the messinian evaporites in the eastern mediterranean represent a world class site to study thin skinned salt tectonic processes like gravity gliding or gravity spreading in contrast to the mesozoic evaporites in the atlantic the related structures are just slightly overprinted by additional tectonic events new high resolution reflection seismic data image for the first time the entire lateral succession of gravity gliding related features as they were suggested by analog models and demonstrate therewith the validity of those models for the messinian evaporites all three regimes of extension translation and compression are present within the range of the seismic profiles however additional observations lead to an adapted and improved model the generation of a critical slope angle caused by subsidence of the levantine basin is considered to be the main driving force for the thin skinned salt tectonics and the lateral basinward creep of the basinal messinian evaporites in the extensional section beneath or near to the continental slope where the basinal evaporites have been withdrawn listric and antithetic listric growth faults rollovers and keystone grabens form asymmetric turtleback structures above salt welds and salt rollers further basinwards an area with little or no deformation of the evaporites defines the translational segment in the compressional region the lower and thickest part of the evaporites show ductile deformation buckle folds and the upper evaporites reveal brittle deformation reverse faults and pop up structures here the basinal evaporites have a maximum thickness of about 1500 m the extensional zone shows continuous synsedimentary tectonic activity until recent times whereas the compressional structures have developed later in a rather sudden event there is clear evidence for neotectonics off the israeli coast which is not related to salt dynamics faults cut through the entire pile of evaporites and the post messinian overburden where the faults pierce the sea floor mud escape structures have been observed deep rooted faults have been interpreted at the base of the messinian paleo slope suggesting a shear zone off israel and parallel to the dead sea transform

extrusion and radial spreading beyond a closing channel abstract the development of experimental models of an extruding spreading zone beyond a closing channel is studied and a possible natural example described the strain pattern folding and radial displacements within the extruding spreading zone are analysed folds developed in the closing channel are either passively rotated or refolded when carried into the spreading zone a simple theoretical model of the experiments demonstrates that the stretching lineation is radial and parallel to the displacement direction towards the base and the front of the extruding spreading zone but perpendicular towards the top an intermediate domain with no stretching lineation separates the radial and concentric domains and corresponds to a transition through a uniaxial oblate ellipsoid k 0

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

sedimentary flattening and multi extensional deformation along the west african margin abstract the structural world is usually divided into compressional and extensional zones and this tectonic style is representative of the regional deformation which leads to shortening or extension along the west african margin there is no evidence of crustal extension since 100 my ago but the post salt series are intensely deformed by gravity and sedimentary loading normal faults as well as reverse faults are present the modes of deformation of such an area are described using large 3d seismic data sets analogue models and cross section and map restorations results show that 1 surface rotations are large at a regional scale 2 plane deformation is not a valid hypothesis across the margin the amount of extension parallel to the coast being on the same order of magnitude as the extension perpendicular to the margin 3 the surface area of the beds are not preserved the data indicate that the deformation of the shale in such a context is a ductile flow due to body forces and sedimentary loading here called sedimentary flattening competent layers sand prone such as sheet sand lobes or channels constitute passive markers which follow the ductile flow in a brittle mode resulting in boudinage

a high resolution dual doppler technique for fixed multiantenna airborne radar a new technique is presented for the analysis of data collected by pairs of aircraft ac mounted fixed radar beams directed 30deg apart leading to two dimensional wind field syntheses in the horizontal and vertical planes the technique was applied to the 95 ghz wyoming cloud radar wcr configurations aboard the university of wyoming king air and the national center for atmospheric research c 130 research ac the construction of the data grid allows to closely follow the ac flight attitude and thus the beam scanned surfaces with a resolution between 30 and 45 m a weighted least squares method is employed to solve the velocity inverse decomposition problem for every valid grid cell the effect on the solution of the nonmeasured cross plane wind component is minimized by using an external estimate of the ambient wind the error sources are discussed and maximum expected values for the velocity field errors are provided with reference to the radar system the data collection process and specific aspects of the target under investigation these uncertainties 1 2 m s are quantified for two case studies that show the potential of the technique in retrieving the kinematic field in transects of cumulus and stratus clouds the technique produces smooth fine scale kinematic fields although each velocity point is the result of an independent calculation and no binding constraint is imposed among neighboring points as is done in other dual doppler techniques

atlantic meridional overturning circulation slowdown cooled the subtropical ocean 1 observations show that the upper 2 km of the subtropical north atlantic ocean cooled throughout 2010 and remained cold until at least december 2011 we show that these cold anomalies are partly driven by anomalous air sea exchange during the cold winters of 2009 2010 and 2010 2011 and more surprisingly by extreme interannual variability in the ocean s northward heat transport at 26 5 n this cooling driven by the ocean s meridional heat transport affects deeper layers isolated from the atmosphere on annual timescales and water that is entrained into the winter mixed layer thus lowering winter sea surface temperatures here we connect for the first time variability in the northward heat transport carried by the atlantic meridional overturning circulation to widespread sustained cooling of the subtropical north atlantic challenging the prevailing view that the ocean plays a passive role in the coupled ocean atmosphere system on monthly to seasonal timescales

the enigma of the albian gap spatial variability and the competition between salt expulsion and extension the albian gap is a uniquely large up to 65 km wide and 450 km long enigmatic salt related structure in the santos basin offshore brazil it is located near the basin margin and trends ne i e subparallel to the brazilian coastline the gap is characterized by a near complete absence of albian strata above depleted aptian salt its most remarkable feature is an equivalently large equally enigmatic basinward dipping supra salt rollover that contains a post albian sedimentary succession that is up to 9 km thick owing to its unique geometry size and counter regional aspect the origin and evolution of the albian gap has been the centre of debate for 25 years this debate revolves around two competing models that is did it form as a result of thin skinned i e supra salt extension or progradational loading and salt expulsion the extension driven model states that the albian gap and overlying rollover formed as a result of post albian gravity driven extension accommodated by slip on a large counter regional listric normal fault the cabo frio fault conversely the expulsion driven hypothesis states that the albian gap was established earlier during the albian and that post albian deformation was controlled by differential loading vertical subsidence and basinward salt expulsion in the absence of significant lateral extension this study utilizes a large c 76 000 km2 dense 4 8 km line spacing depth migrated 2d seismic dataset that fully covers and thus permits for the first time a detailed quasi 3d structural analysis of the entire albian gap in this study we focus on 1 the evolution of base salt relief and the original salt thickness variations and 2 the geometry of the post albian rollover and its related faults and salt structures to constrain the kinematics of the albian gap and how this relates to the evolution of the base salt relief we also apply novel structural restoration workflows that incorporate flexural isostasy in addition to a detailed sequential reconstruction of the intra gap rollover sequences our results show that the geometry and kinematics of the albian gap vary along strike and that both post albian extension and expulsion play a significant role in its evolution basinward dipping growth wedges salt rollers and listric normal faults record extension whereas sigmoidal wedges halokinetic sequences and upturned near diapir flaps the latter two associated with large diapirs bounding the downdip edge of the gap record basinward salt expulsion and inflation where the albian gap is relatively wide 50 km these processes alternate and operate at approximately equal proportions our results are consistent with the amount of basinward translation inferred from the analysis of ramp syncline basins located downdip on the sao paulo plateau our results seemingly reconcile one of the longest running debates in salt tectonics as well as having more general implications for understanding the regional kinematics and dynamics of salt related structures in other salt basins in particular the controls on the development of large counter regional faults supplementary material uninterpreted versions of the seismic sections are available at https doi org 10 6084 m9 figshare c 5023088

observations of large wind shear above the marine boundary layer near point buchon california abstractparticularly strong winds along the coast of southern california on 24 may 2012 were measured by the wyoming king air research aircraft during the precision atmospheric marine boundary layer experiment preamble the fast flow is bounded laterally by the coastal topography and vertically by a pronounced temperature inversion separating the cool moist air in the marine boundary layer mbl from the warm dry air aloft many studies have investigated the response of this two layer flow to changes in the coastline by invoking hydraulic theory which explains the essential characteristics including changes in mbl depth and the attendant wind processes occurring just above the mbl are important to the low level thermodynamic and kinematic structure observations on this day demonstrate how the large shear above the mbl can impact the lower atmosphere a typical two layer system was observed north of point buchon which was supercritical around point buchon the depth of the mbl decreased and wind i

analysis of folding and deformation within layered evaporites in blocks bm s 8 9 santos basin brazil the sao paulo plateau in the deepwater santos basin is the site of numerous recent pre salt petroleum discoveries the area is characterized by a thick sequence of layered evaporites comprising primarily halite with subordinate anhydrite and carnalite and trace amounts of other minerals the sequence is divided into six stratigraphic packages three relatively competent beams containing the bulk of the stronger anhydrite and three relatively weak detachment layers observed structural styles range from the simple to the complex including upright open folds inclined thrusted folds recumbent isoclinal folds sheath folds and superposed folds mul tiple detachments lead to polyharmonic folding disharmonic folding and overtightened folds major anticlinal structures contain acoustically transparent material surrounding disrupted highly deformed pieces of the lower two beams the deformation is non coaxial with anticlines forming a polygonal pattern and fold hinges that are highly curvilinear the sao paulo plateau is a contractional province that formed in response to proximal extension at the albian gap during convergent gravity gliding spreading of the margin shortening possibly began during the waning stages of evaporite deposition but the bulk of the movement occurred during the santonian mid eocene the evaporite sequence shortened much more than the cover because of extreme updip attenuation and consequent basinwards flow beneath the cover deeper levels of evaporite exhibit more shortening due to strain partitioning across internal detachments

fluid pressure and effective stress in sandbox models abstract we have done a series of simple tests on sandpacks involving upward flow of compressed air through the pores and its effect on the yield strength the ultimate objective is to model deformation coupled with fluid flow in sedimentary basins for all tests we used a single batch of fontainebleau sand sieved to a grain size between 0 200 and 0 315 mm poured into a cylindrical container and then fluidized the density of this sand was 1 585 g cm3 irrespective of sand thickness the lithostatic pressure was proportional to the thickness of the sandpack a yield envelope was obtained by shearing the sandpack horizontally compressed air entered the base of the sandpack and flowed upwards through the pore spaces for 69 measurements on air flow without shearing a plot of discharge velocity versus gradient of fluid pressure is close to a straight line verifying darcy s law and yielding an intrinsic permeability of about 1 7 darcy for the sand for 72 tests on simultaneous shearing and fluid flow the estimated effective stress lithostatic stress minus estimated pore fluid pressure ranged from 0 to 1600 pa and the pore fluid ratio between air pressure and lithostatic pressure from 0 0 to 1 0 a plot of shear stress versus effective stress at failure is almost linear verifying terzaghi s principle of effective stress the best fit slope coefficient of internal friction is about 0 55 and the intercept on the shear stress axis cohesion is less than 85 pa the tests show that it is feasible to use compressed air within sandpacks as a means of modelling deformation coupled with fluid flow the next step will be to build sandbox models of layered sequences and to investigate detachments caused by abnormal fluid pressures

reconstruction of historical sea surface temperatures using empirical orthogonal functions abstract studies of climate variability often rely on high quality sea surface temperature sst anomalies although the high resolution national centers for environmental prediction formerly the national meteorological center optimum interpolation oi sst analysis is satisfactory for these studies the oi resolution cannot be maintained before november 1931 due to the lack of satellite data longer periods of ssts have come from traditional analyses of in situ ship and buoy sst observations alone a new interpolation method is developed using spatial patterns from empirical orthogonal functions e0fs that is a principal component analysis to improve analyses of sst anomalies from 1950 to 1981 the method uses the more accurate oi analyses from 1982 to 1993 to produce the spatial eofs the dominant eof modes which correspond to the largest variance are used as basis functions and are fit in a least squares sense to the in situ data to determine the time dependence of each mode a complete field

internal structure kinematics and growth of a salt wall insights from 3 d seismic data the detailed kinematics of natural salt walls remain elusive because such structures are typically poorly exposed at outcrop only partly exposed in mine workings and diapiric salt is typically poorly reflective in seismic data we use three dimensional seismic and borehole data from offshore brazil to investigate how structural styles vary along strike within a spectacularly well imaged salt wall deformed layering in the salt allows us to map complex seismic scale structures in the wall within the wall s relatively simple external shape is a range of previously undocumented structural styles produced by 1 initial upwelling and formation of a wall parallel anticline due to regional extension and differential overburden load 2 breaching of the anticline rayleigh taylor overturn and emplacement of an intrasalt allochthonous sheet driven by a density inversion and 3 internal thrusting of the mature diapir caused by regional compression this study is arguably the first detailed documentation of the internal structure and kinematics of a natural salt wall highlighting the presence of abruptly varying intrasalt structural styles the structures identified and the inferred kinematics suggest that given specific mechanical stratigraphy density driven overturn within salt diapirs can play a key role in their growth

large scale variabilities of wintertime wind stress curl field in the north pacific and their relation to atmospheric teleconnection patterns 1 wintertime wind stress curl wsc field in the north pacific is investigated to reveal large scale variabilities and their relation to atmospheric teleconnection patterns it is found that the leading empirical orthogonal function eof and the next three rotated eof modes of wintertime wsc anomalies well correspond to those of atmospheric teleconnection patterns i e pacific north american pna western pacific wp tropical northern hemisphere tnh and eastern pacific ep teleconnection patterns respectively time coefficient of the first eof mode well correlates with the north pacific index and does with the pacific decadal oscillation index to some degree it is also found that sverdrup transports in the two zonal bands of 25 n 30 n and 42 5 n 47 5 n have highly negative correlation and these variations can be represented by the forcing field of the first eof mode the pna forcing makes both subtropical and subpolar gyres spin up spin down simultaneously

origins of aircraft damaging clear air turbulence during the 9 december 1992 colorado downslope windstorm numerical simulations and comparison with observations results from numerical simulations of the colorado front range downslope windstorm of 9 december 1992 are presented although this case was not characterized by severe surface winds the event caused extreme clearair turbulence cat aloft as indicated by the severe structural damage experienced by a dc 8 cargo jet at 9 7 km above mean sea level over the mountains detailed measurements from the national oceanic and atmospheric administration environmental research laboratories environmental technology laboratory doppler lidar and wind profilers operating on that day and from the defense meteorological satellite program satellite allow for a uniquely rich comparison between the simulations and observations four levels of grid refinement were used in the model the outer domain used national centers for environmental prediction data for initial and boundary conditions the finest grid used 200 m in all three dimensions over a 48 km by 48 km section the range of resolution and domain coverage were sufficient to resolve the abundant variety of dynamics associated with a time evolving windstorm forced during a frontal passage this full range of resolution and model complexity was essential in this case many aspects of this windstorm are inherently three dimensional and are not represented in idealized models using either 2d or so called 2d 3d dynamics both the timing and location of wave breaking compared well with observations the model also reproduced cross stream wavelike perturbations in the jet stream that compared well with the orientation and spacing of cloud bands observed by satellite and lidar model results also show that the observed cat derives from interactions between these wavelike jet stream disturbances and mountain forced internal gravity waves due to the nearly east west orientation of the jet stream these two interacting wave modes were orthogonal to each other thermal gradients associated with the intense jet stream undulations generated horizontal vortex tubes hvts aligned with the mean flow these hvts remained aloft while they propagated downstream at about the elevation of the aircraft incident and evidence for such a vortex was seen by the lidar the model and observations suggest that one of these intense vortices may have caused the aircraft incident reports of strong surface gusts were intermittent along the front range during the period of this study the model showed that interactions between the gravity waves and flow aligned jet stream undulations result in isolated occurrences of strong surface gusts in line with observations the simulations show that strong shears on the upper and bottom surfaces of the jet stream combine to provide an episodic downburst of turbulence in the present case the perturbations of the jet stream provide a funnel shaped shear zone aligned with the mean flow that acts as a guide for the downward transport of turbulence resulting from breaking gravity waves the physical picture for the upper levels is similar to the surface gusts described by clark and farley resulting from vortex tilting the cat feeding into this funnel came from all surfaces of the jet stream with more than half originating from the vertically inclined shear zones on the bottom side of the jet stream visually the downburst of turbulence looks similar to a rain shaft plummeting to the surface and propagating out over the plains leaving relatively quiescent conditions behind

plio quaternary thin skinned tectonics along the crustal front flexure of the southern central andes a record of the regional stress regime or of local tectonic driven gravitational processes we present here a record of plio pleistocene deformations above the flexural front of the southern central andes of argentina we combine a seismic profile with structural and geomorphological observations to show that thin skinned extension located on top of the crustal front flexure is coeval with thin skinned shortening at the toe of the topographic bulge the seismic line shows that a flat zone with no internal deformation separates the stretched and shortened domains such features are usually interpreted as the result of strike slip faulting along basement faults or tangential longitudinal strain folding in the soft sedimentary cover above crustal bending we propose an alternative linking extension at the apex of the crustal anticline to basal contraction by the downslope translation of a rigid thin nappe of sediments 30 30 km2 in area above evaporites at a depth of 700 900 m the size of such a process is unusually large onshore 630 810 km3 but mimics the gravity gliding observed in deltas and passive margins since this process disconnects zones with a shallow stress field from deeper crustal levels it could allow extension above a compressive deformation front and should not be interpreted merely as a record of the crustal stress regime large scale gravity gliding of the cover down the slope of a structural high could also explain some of the extension observed in mountain hinterlands

extreme air sea interaction over the north atlantic subpolar gyre during the winter of 2013 2014 and its sub surface legacy exceptionally low north american temperatures and record breaking precipitation over the british isles during winter 2013 2014 were interconnected by anomalous ocean evaporation over the north atlantic subpolar gyre region spg this evaporation or oceanic latent heat release was accompanied by strong sensible heat loss to the atmosphere the enhanced heat loss over the spg was caused by a combination of surface westerly winds from the north american continent and northerly winds from the nordic seas region that were colder drier and stronger than normal a distinctive feature of the air sea exchange was that the enhanced heat loss spanned the entire width of the spg with evaporation anomalies intensifying in the east while sensible heat flux anomalies were slightly stronger upstream in the west the immediate impact of the strong air sea fluxes on the ocean atmosphere system included a reduction in ocean heat content of the spg and a shift in basin scale pathways of ocean heat and atmospheric freshwater transport atmospheric reanalysis data and the en4 ocean data set indicate that a longer term legacy of the winter has been the enhanced formation of a particularly dense mode of subpolar mode water spmw one of the precursors of north atlantic deep water and thus an important component of the atlantic meridional overturning circulation using particle trajectory analysis the likely dispersal of newly formed spmw is evaluated providing evidence for the re emergence of anomalously cold spmw in early winter 2014 2015

the evolution of lee wave rotor activity in the lee of pike s peak under the influence of a cold frontal passage implications for aircraft safety abstract a lee wave rotor system interacting with an approaching cold front in the lee of pike s peak near colorado springs colorado on 1 april 1997 is studied observationally and numerically dynamical effects associated with the approaching cold front caused the amplification of the evolving lee wave and rotor creating increasingly more hazardous flight conditions for nearby airports the rapidly evolving winds measured by a doppler lidar and 915 mhz wind profilers and simulated by the regional atmospheric modeling system rams produced light to moderate turbulence for a research aircraft making missed approaches at the colorado springs airport during the wave amplification phase as the cold front approached the foothills the lee wave rotor system ended abruptly reducing hazardous flight conditions the doppler lidar s detailed measurements of the lee wave rotor system allowed for an evaluation of rams ability to capture these complex wind features qualitative and quantitative comparisons betw

experiments on shortening of a 4 layer model of the continental lithosphere davy ph and cobbold p r 1991 experiments on shortening of a 4layer model of the continental lithosphere in p r cobbold editor experimental and numerical modelling of continental deformation tecronophysics 188 l 25 we present an experimental method for modelhng lithospheric deformation the method is based on a simplified profile of lithosphere rheology where only four layers are considered brittle crust ductile crust brittle mantle and ductile mantle the strengths of the four layers calculated from laboratory determined flow laws depend strongly on geothenns and slightly on strain rates and deformation regimes the rheological profiles of the lithosphere have been recreated in experimental models built with analog materials sand silicone putty and golden syrup which flow under their own weight during lithospheric shortening the style of deformation depends on the relative strengths of the four layers especially those in the mantle of special importance is the existence or non existence of a brittle mantle the initial stages of compression often produce flexures or buckles without local isostatic compensation buckling exerts a strong control on the localisation of thrust faults in later stages the thrusts tend to form at the inflexion points of buckles the style of crustal thickening depends on the relative thicknesses and resistances of the lithospheric layers in 2 layer lithospheric models without resistant mantle shortening was concentrated upon a small number of thrusts widely spaced in 3 layer models shortening was concentrated into a large number of reverse faults more closely spaced and more steeply dipping than before in clayer models a single thrust formed in the brittle mantle motion on this thrust dragged the crustal layers down forming an asymmetric crustal root with steep imbricate slices

how normal faulting and sedimentation interact to produce listric fault profiles and stratigraphic wedges abstract in a series of scale experiments we generated listric normal faults by extending models composed of colored sand layers deposited at regular time intervals throughout deformation during syntectonic sedimentation progressive bulk extension along a single set of faults caused domino type tilting of fault blocks underlying tilted faults propagated upwards with constant dips into newly sedimented layers hence fault profiles become progressively more listric tilting of the free surface resulted in asymmetrical depressions and in fan shaped deposits stepwise or continuous geometric models of domino tilting and synchronous sedimentation yield the same structural and stratigraphic features as observed in the sand models the continuous geometric model shows that a critical parameter governing fault curvature is the ratio r between rates of bulk strain and sedimentation both types of models reveal that synchronous sedimentation and bulk extension are capable by themselves of generating listric normal faults

energy flux and wavelet diagnostics of secondary mountain waves abstract in recent years aircraft data from mountain waves have been primarily analyzed using velocity and temperature power spectrum and momentum flux estimation herein it is argued that energy flux wavelets i e pressure velocity wavelet cross spectra provide a more powerful tool for locating and classifying different types of mountain waves in the first part of the paper pressure velocity cross spectra using various linear mountain wave solutions are shown to be capable of disentangling collocated waves with different propagation directions and wavelength a field of group velocity vectors can also be determined in the second part the energy flux wavelet technique is applied to five cases of mountain waves entering the stratosphere from the terrain induced rotor experiment t rex in 2006 perturbation pressure along the flight track is determined using aircraft static pressure corrected hydrostatically with gps altitude in four of the cases collocated long up propagating and short down prop

hanging wall fault kinematics and footwall collapse in listric growth fault systems we describe the structure of a listric growth fault system from se asia using high resolution 3 d seismic data the fault system shows systematic changes in geometry and kinematics that are sympathetic with along strike changes in the structure of the bounding fault where the position of the bounding fault remained fixed there is an overall landward decrease in the age of the hanging wall growth faults along strike three phases of footwall collapse caused by the active bounding fault stepping back into the footwall block were responsible for the punctuated stepwise landward migration of the rollover hinge and associated hanging wall growth faults during extension the migration of these hanging wall structures is similar to that predicted by simple analogue models with fixed detachment surfaces care should therefore be taken in defining kinematic models in areas where the geometry of the bounding fault is either poorly defined or unknown

role of the gulf stream and kuroshio oyashio systems in large scale atmosphere ocean interaction a review abstract ocean atmosphere interaction over the northern hemisphere western boundary current wbc regions i e the gulf stream kuroshio oyashio and their extensions is reviewed with an emphasis on their role in basin scale climate variability sst anomalies exhibit considerable variance on interannual to decadal time scales in these regions low frequency sst variability is primarily driven by basin scale wind stress curl variability via the oceanic rossby wave adjustment of the gyre scale circulation that modulates the latitude and strength of the wbc related oceanic fronts rectification of the variability by mesoscale eddies reemergence of the anomalies from the preceding winter and tropical remote forcing also play important roles in driving and maintaining the low frequency variability in these regions in the gulf stream region interaction with the deep western boundary current also likely influences the low frequency variability surface heat fluxes damp the low frequency sst anomalies ove

radial gravitational gliding on passive margins abstract gravitational gliding of uppermost sediments down a passive margin is possible if there is a basal layer of evaporite or other soft material to allow detachment in examples from the gulf of mexico and the brazilian margin gliding has produced three main structural domains an uppermost domain of downdip extension an intermediate domain of rigid gliding and a lowermost domain of downdip contraction domain boundaries are established by changes in slope in this paper we examine three kinds of gravitational gliding depending on the paths followed by material particles in ideal parallel gliding particle paths are parallel straight lines trending downslope this should occur where the margin is perfectly straight in ideal radial gliding particle paths are radii of a circle and the margin is shaped like a circular cone natural margins will not have ideal shapes but divergent gliding will tend to occur off coastal salients convergent gliding off coastal re entrants a simple kinematic model based on ductile behaviour illustrates some essential features of radial gliding changes in radius during divergent gliding produce strike parallel extension during convergent gliding they produce strike parallel contraction vertical strains also differ divergent gliding produces an uppermost domain of strong vertical thinning balanced by extensions in all horizontal directions similarly convergent gliding produces a lowermost domain of strong vertical thickening balanced by contractions in all horizontal directions these deformed states cannot be restored by simple techniques based on section balancing we have done three experiments using analogue materials sand to model the brittle behaviour of sediments silicone putty to model the ductile behaviour of basal layers of evaporite the experiments were properly scaled to account for gravitational forces experiment i reproduced convergent gliding above a basement with a conical upper surface strike parallel contraction was responsible for radial folds on the lower slopes the lowermost domain had a complex fold pattern indicating contraction in all horizontal directions experiment 2 reproduced divergent gliding above a basement with a pyramidal upper surface strike parallel extension produced radial rifts on the upper slopes the uppermost domain had a complex polygonal pattern of normal faults indicating extension in all horizontal directions experiment 3 also reproduced divergent gliding but due to non uniform sediment thickness we have examined the many seismic profiles both downdip and alongstrike available for the brazilian margin alongstrike profiles show structures which we attribute to strike parallel strains around the santos re entrant syn sedimentary growthfolds indicate strike parallel contraction increasing downslope this argues for a mechanism of convergent gliding in contrast around the campos salient normal growth faults and associated salt rollers indicate strike parallel extension decreasing downslope this argues for a mechanism of divergent gliding the pattern of oil fields in the campos area including the giant marlim field seems to be closely controlled by divergent gravitational gliding and associated processes radial gliding should occur on other passive margins as well especially where the coastline is sinuous structures around the western gulf of of mexico seem to indicate convergent gliding at the scale of the entire gulf structures at a smaller scale around the mississippi delta seem to indicate divergent gliding

winter to winter recurrence of sea surface temperature salinity and mixed layer depth anomalies abstract the mean seasonal cycle of mixed layer depth mld in the extratropical oceans has the potential to influence temperature salinity and mixed layer depth anomalies from one winter to the next temperature and salinity anomalies that form at the surface and spread throughout the deep winter mixed layer are sequestered beneath the mixed layer when it shoals in spring and are then re entrained into the surface layer in the subsequent fall and winter here we document this re emergence mechanism in the north pacific ocean using observed ssts subsurface temperature fields from a data assimilation system and coupled atmosphere ocean model simulations observations indicate that the dominant large scale sst anomaly pattern that forms in the north pacific during winter recurs in the following winter the model simulation with mixed layer ocean physics reproduced the winter to winter recurrence while model simulations with observed ssts specified in the tropical pacific and a 50 m slab in the north pacific did not this difference between the model results indicates that the winter to winter sst correlations are the result of the re emergence mechanism and not of similar atmospheric forcing of the ocean in consecutive winters the model experiments also indicate that sst anomalies in the tropical pacific associated with el nino are not essential for re emergence to occur the recurrence of observed sst and simulated sst and sss anomalies are found in several regions in the central north pacific and are quite strong in the northern 50 n part of the basin the winter to winter autocorrelation of sss anomalies exceed those of sst since only the latter are strongly damped by surface fluxes the re emergence mechanism also has a modest influence on mld through changes in the vertical stratification in the seasonal thermocline

detailed dual doppler structure of kelvin helmholtz waves from an airborne profiling radar over complex terrain part i dynamic structure abstractkelvin helmholtz kh waves are remarkably common in deep stratiform precipitation systems associated with frontal disturbances at least in the vicinity of complex terrain as is evident f

why does reemergence of winter sea surface temperature anomalies not occur in eastern mode water areas 1 in terms of buoyancy flux winter mixed layer depth and mode water thickness in summer we explore the causes why reemergence does not occur in the formation areas of the north pacific eastern subtropical mode water npestmw and the north atlantic madeira mode water nammw it is found that as season goes by the thicknesses of these mode waters become quickly thinner due to vigorous salt finger type convection throughout the water column in contrast to those of the other mode waters correspondingly mode waters lying under the shallow summer mixed layer quickly lose their water properties in addition it is found that in these areas net buoyancy flux integrated through a year is almost zero while in the other mode water areas where reemergence occurs net buoyancy flux is negative the ocean s loss to some degree based on these facts we can conclude that the formation areas of npestmw and nammw are the regions having unfavorable conditions for an occurrence of reemergence

rollovers in salt tectonics the inadequacy of the listric fault model abstract rollover anticlines are syn sedimentary extensional structures common in salt tectonics that are classically considered to result from layer bending during hangingwall displacement above a listric normal fault however theoretical considerations and seismic images of natural examples put in question the validity of the listric fault model from which rollover growth is steady state by nature and controlled by the relative displacement of two blocks we used laboratory experiments of gravity driven deformation of brittle ductile models simulating salt tectonics processes to study in which circumstances rollovers are obtained both in time and space it is argued that rollover growth is a nonsteady process that results from a mechanical instability whose critical lifetime can be divided in three characteristic stages birth growth and decay in kinematic terms the development of a synthetic or antithetic rollover requires a three block system an upslope block and a downslope block that move downslope and that separate from each other on top of an extending decollement layer lying above a basement block synthetic and antithetic rollovers developed with upward concave shapes whatever the sense of shear in the salt layer and can pass laterally to each other without transform fault this points out that the concave shape of a rollover base is not an argument in favour of listric faulting the concave shape simply results from the connection between a steeply dipping normal fault and a flat lying or gently dipping decollement

the reemergence of sst anomalies in the north pacific ocean abstract sea surface temperature sst data and two different upper ocean temperature analyses are used to study the winter to winter recurrence of sst anomalies in the north pacific ocean the ssts recur when temperature anomalies that form in the deep ocean mixed layer in late winter early spring are isolated from the atmosphere in the summer seasonal thermocline and then reemerge at the surface when the mixed layer deepens during the following fall winter this reemergence mechanism is evaluated over the basin by correlating the time series of the leading pattern of ocean temperature anomalies in the summer seasonal thermocline 60 85 m in august september with sst anomalies over the course of the year the results indicate that the dominant large scale sst anomaly pattern that forms in the north pacific during late winter with anomalies of one sign in the central pacific and the opposite sign along the coast of north america is sequestered in the seasonal thermocline in summer and returns to the

re emerging ocean temperature anomalies in late 2010 associated with a repeat negative nao northern europe was influenced by consecutive episodes of extreme winter weather at the start and end of the 2010 calendar year a tripole pattern in north atlantic sea surface temperature anomalies sstas associated with an exceptionally negative phase of the north atlantic oscillation nao characterized both winter periods this pattern was largely absent at the surface during the 2010 summer season however equivalent sub surface temperature anomalies were preserved within the seasonal thermocline throughout the year here we present evidence for the re emergence of late winter 2009 10 sstas during the following early winter season of 2010 11 the observed re emergence contributes toward the winter to winter persistence of the anomalous tripole pattern considering the active influence of the oceans upon leading modes of atmospheric circulation over seasonal timescales associated with the memory of large scale sea surface temperature anomaly patterns the re emergence of remnant temperature anomalies may have also contributed toward the persistence of a negative winter nao and the recurrence of extreme wintry conditions over the initial 2010 11 winter season

aerial observations of the yugoslavian bora abstract the first aircraft observations of the bora in yugoslavia were accomplished during the alpex project in 1982 data from all five alpex bora flights have been analyzed in a comparative study of bora structure although the bora varies considerably in depth in the strength of the incoming low level flow and in the direction of the winds aloft several common features are evident these include upstream descent and acceleration beginning where the mountains rise an approximate coincidence between the depth of the uppermost descending streamline and the wind reversal level upstream when a reversal exists a decoupling of the flow aloft associated with a splitting of the inversion and the formation of a thick mixed layer downstream a narrow region of intense turbulence and an ascending jet just downstream of the plunging bora the bora structure is similar in many respects to the boulder windstorm internal hydraulic theory taking into account the decoupling effect of the intermediate layer a

evolution and vertical structure of an undular bore observed on 20 june 2015 during pecan abstractthis study documents the evolution of an impressive largely undular bore triggered by an mcs generated density current on 20 june 2015 observed as part of the plains elevated convection at night pecan experiment the university of wyoming king air with profiling nadir and zenith viewing lidars sampled the south bound bore from the time the first bore wave emerged from the nocturnal convective cold pool and where updrafts over 10 m s 1 and turbulence in the wave s wake were encountered through the early dissipative stage in which the leading wave began to lose amplitude and speed through most of the bore s life cycle its second wave had a higher or equal amplitude relative to the leading wave striking roll clouds formed in wave crests and wave energy was detected to about 5 km agl the upstream environment indicates a negative scorer parameter region due to flow reversal at midlevels providing a wave trapping mechanism the observed bore strength of 2 4 2 9 and speed of 15 16 m s 1 agree

properties formation and dissipation of the north pacific eastern subtropical mode water and its impact on interannual spiciness anomalies abstract the properties formation and dissipation of the north pacific eastern subtropical mode water estmw their interannual variability and impact on spiciness anomalies in the upper permanent pycnocline were investigated using argo profiling float data in 2005 2015 the core temperature and salinity of estmws were horizontally compensated to a constant density and core potential density concentrates in a range of 24 5 25 2 kg m 3 with two distinct peaks estmws showed different spatial distribution and persistence for its core potential density denser estmws with a potential density of 24 9 25 2 kg m 3 were formed in winter mixed layer depth maximum centered at 30 n 140 w and lighter estmws of 24 5 24 9 kg m 3 were formed south and east of it after formation through shoaling of the winter mixed layer the former persisted until the following autumn and a small part of it subducted in winter while the latter dissipated in summer the formation region of estmw corresponded to the summer sea surface density maximum resulting from its poleward sea surface salinity front sea surface density maximum maintains weak stratification during summer preconditioning the deepening of the winter mixed layer and hence the formation of estmws a relationship between the estmw formation region and the summer sea surface density maximum was also found in the north atlantic and the south pacific implying the importance of sea surface salinity fronts and the associated summer sea surface density maximum to estmw formation interannual variations of estmw reflected that of the winter mixed layer in its formation region and the thickness of estmw was related to the pacific decadal oscillation estmw contributed to the occurrence of spice injection and affected spiciness anomalies in the upper permanent pycnocline through its formation and dissipation

restoration in plan view of faulted upper cretaceous and oligocene horizons and its bearing on the history of salt tectonics in the campos basin brazil abstract in the campos basin atlantic margin of brazil cretaceous and tertiary sediments show abundant evidence for thin skinned deformation above a layer of aptian salt near the coast there is a domain of downslope extension further offshore a domain of donwslope contraction thus we attribute the domainal pattern to gravitational gliding on the salt layer gravitational gliding appears to be driven primarily by surface slopes each material particle tends to move in the direction of steepest slope if topography is irregular particle paths diverge or converge deformation then differs from a plane strain and vertical cross sections cannot be individually balanced or restored we have therefore developed a method for restoring non plane deformation in extensional domains assuming that blocks between faults are rigid we restore stratigraphic horizons in plan view by least squares minimization of distances across fault separations cut off lenses obtaining fields of finite horizontal displacements for selected areas in the extensional domain of the campos basin where divergent gravitational gliding has led to extension in various horizontal directions we have restored two stratigraphie markers an upper cretaceous and an oligocene horizon for each horizon displacement vectors diverge seawards forming a fanlike pattern with a degree of mirror symmetry nevertheless there are major differences between the upper cretaceous and oligocene patterns both for faults and for displacements we infer that this resulted from the development during the tertiary of a propagating deltaic front whose sediment load drove the divergent gravitational gliding and induced a new fault pattern

mechanical analysis of a natural example of onland gravity gliding the role of river incision and deposition gravity gliding implies rigid translation of a body down a slope where displacements are parallel to a tilted detachment plane although large scale gravity gliding is commonly observed offshore under conditions of high fluid overpressure and abundant upslope sedimentary supply its occurrence on land is debated we investigate the mechanical feasibility of such a process as well as the role of fluvial incision and sedimentation down the slope in the initiation of the gliding we use a two dimensional 2 d finite element model combined with a 2 d failure analysis approach the numerical models simulate the deformation and provide quantitative estimates of the failure criteria at the head and toe of the overburden analytical solutions approximate the numerical results by taking into account the fluvial incision and sedimentation the internal friction angle and the thickness and length of the overburden our models are based on a field example in the andean foothills of argentina where gravity gliding of a 1000 m thick section is suspected above a crustal scale anticline the incision and sedimentation reduce and strengthen respectively the downslope resistance to contractional failure the critical slope at which the gliding is initiated is reduced by fluvial incision and increased by sedimentation we show that tectonic uplift may lead to large scale gravity gliding on land where the overburden thickness is less than 2000 m incision facilitates and localizes the frontal shortening incision greater than 1000 m may trigger gliding for overburden up to 4000 m thick while sedimentation thicker than 1000 m inhibits gliding these results show that thin skinned onland gravity gliding could be common in tectonically active regions where incision is important

the subtropical mode waters of the south pacific ocean abstract the subtropical mode waters stmw of the southwestern pacific ocean are described including their physical characteristics spatial distribution and temporal variability stmw is a thermostad or minimum in stratification having temperatures of about 15 19 c and vertical temperature gradient less than about 2 c per 100 m typical salinity is 35 5 psu at 16 5 c the stmw layer is formed by deep mixing and cooling in the eastward flowing waters of the separated east australia current surface mixed layers are observed as deep as 300 m north of new zealand in winter in the center of a recurring anticyclonic eddy the stmw thermostad in the south pacific is considerably weaker than its counterparts in the north atlantic and north pacific a contrast that may help to discriminate between physical processes contributing to its formation a quarterly time series of expendable bathythermograph transects between new zealand and fiji is used to study the temporal variability of stmw large fluctuatio

boundary layer turbulence and orographic precipitation growth in cold clouds evidence from profiling airborne radar data abstractairborne vertically pointing doppler radar data collected in 10 winter storms over the medicine bow range in wyoming are used to examine the importance of boundary layer bl turbulence for orographic precipitation growth in all 10 cases the cloud base temperature was below 0 c and the bulk froude number was more than 1 0 implying little or no blocking of the flow by the mountain barrier seven of the 10 storms sampled were postfrontal with weak static stability and relatively shallow cloud tops doppler vertical velocity transects depict an approximately 1 km deep turbulent layer draped over the terrain sometimes clearly distinct from the stratified flow in the free troposphere aloft where vertical motion is largely controlled by gravity wave dynamics spectral analysis of near surface doppler vertical velocity data in terrain following coordinates reveals an inertial subrange with decreasing power with height toward the bl top the composite of radar data profiles from the 10 flights is ana

the persistence of winter sea surface temperature in the north atlantic abstract the impact of the seasonal variations of the mixed layer depth on the persistence of sea surface temperature sst anomalies is studied in the north atlantic using observations a significant recurrence of winter sst anomalies during the following winter occurs in most of the basin but not in the subtropical area of strong subduction when taking reemergence into account the e folding timescale of winter sst anomalies generally exceeds 1 yr and is about 16 months for the dominant sst anomaly tripole the influence of advection by the mean oceanic currents is investigated by allowing for a displacement of the maximum recurrent correlation and alternatively by considering the sst anomaly evolution along realistic mean displacement paths taking into account the nonlocality of the reemergence generally increases the wintertime persistence most notably in the northern part of the domain the passive response of the mixed layer to the atmospheric forcing thus has a red spectrum down to near dec

dynamics of sea surface temperature anomalies in the southern ocean diagnosed from a 2d mixed layer model we analyze the processes responsible for the generation and evolution of sea surface temperature anomalies observed in the southern ocean during a decade based on a 2d diagnostic mixed layer model in which geostrophic advection is prescribed from altimetry anomalous air sea heat flux is the dominant term of the heat budget over most of the domain while anomalous ekman heat fluxes account for 20 40 of the variance in the latitude band 40 60 s in the acc pathway lateral fluxes of heat associated with anomalous geostrophic currents are a major contributor dominating downstream of several topographic features reflecting the influence of eddies and frontal migrations a significant fraction of the variability of large scale sst anomalies is correlated with either enso or the sam each mode contributing roughly equally the relation between the heat budget terms and these climate modes is investigated showing in particular that anomalous ekman and air sea heat fluxes have a co operating effect with regional exceptions hence the large sst response associated with each mode it is further shown that enso or sam locked anomalous geostrophic currents generate substantial heat fluxes in all three basins with magnitude comparable with that of atmospheric forcings for enso and smaller for the sam except for limited areas enso locked forcings generate sst anomalies along the acc pathway and advection by mean flows is found to be a non negligible contribution to the heat budget exhibiting a wavenumber two zonal structure characteristic of the antarctic circumpolar wave by contrast sam related forcings are predominantly zonally uniform along the acc hence smaller zonal sst gradients and a lesser role of mean advection except in the southwest atlantic while modeled sst anomalies are significantly correlated with observations over most of the southern ocean the analysis of the data model discrepancies suggests that vertical ocean physics may play a significant role in the nonseasonal heat budget especially in some key regions for mode water formation

turbulence characteristics in an elevated shear layer over owens valley abstract characteristics of turbulence in the lower and middle troposphere over owens valley have been examined using aircraft in situ measurements obtained from the terrain induced rotor experiment the two events analyzed in this study are characterized by a deep turbulent layer from the valley floor up to the midtroposphere associated with the interaction between trapped waves and an elevated shear layer kelvin helmholtz kh instability develops above the mountaintop level and often along the wave crests where the richardson number is reduced the turbulence induced by kh instability is characterized by a progressive downscale energy cascade a well defined inertial subrange up to 1 km and large eddies with vertical to horizontal aspect ratios less than unity the turbulence below the mountaintop level is largely shear induced associated with wave steepening and breaking and is more isotropic evaluation of structure functions indicates that while the turbulence energy cascade is predominately dow

feedbacks of sea surface temperature to wintertime storm tracks in the north atlantic abstractin this study the lagged maximum covariance analysis is performed on winter storm track anomalies represented by the meridional heat flux by synoptic scale 2 8 days transient eddies and sea surface temperature sst anomalies in the north atlantic which are both derived from reanalysis datasets spanning the twentieth century the analysis shows significant seasonal and interannual coupling between storm track and sst variations on seasonal time scales it is found that sst anomalies in the preceding early winter november december which are expected to change the lower tropospheric baroclinicity can significantly influence storm tracks in early spring march that is an intensification and slight northward shift of storm tracks in response to a midlatitude sst dipole with a cold pole centered to the southeast of newfoundland and a warm pole in the western subtropical atlantic this storm track response pattern is similar to the storm track forcing pattern in early spring which resembl

gravity driven deformation controlled by the migration of the delta front the plio pleistocene of the eastern niger delta abstract the occurrence in large shelf edge deltas of gravity driven deformation related to overpressured shales is now well documented in many natural examples in this paper we explored the implications of the migration of the delta front on the kinematics of gravity driven deformation in a case where the stratigraphic framework is detailed enough to discuss deformation kinematics and sedimentary supply at high temporal resolution 0 1 myr we determined the deformation for the last 4 myr at the scale of the whole eastern niger delta the upslope extensional domain showed ew asymmetric grabens the transitional domain displayed i deformation restricted to folding to the east and ii a thicker sedimentary wedge and a larger deformation accommodated by thrust related folds to the west the compressional front was a fold and thrust belt extensional deformation decreased in amount and rate over the plio pleistocene it also evolved significantly from distributed over the whole area to localized either to the western or eastern domains over that period the compressional deformation followed the same evolution i e the greater the extension the greater the compression in either time or space demonstrating the strong coupling between the extensional and compressional domains gravity deformation during the plio pleistocene was driven by the continental slope spanning the coastal plain to distal deposits over the oceanic crust about 2800 m of gravity potential the superimposition of the delta front migration area and the extensional domain show that the associated pressure gradient localized the extensional domain deformation was closely linked to migrations of the delta front and the sedimentary supply reaching the delta i the decrease in extension rate over the plio pleistocene is related to a decrease in sedimentary supply over the plio pleistocene and ii the spatial variations in extension intensity and rate are related to spatial variations of sedimentary supply

origin of coast perpendicular extensional faults western gulf of mexico the relationship between an early stage ridge and a late stage fault an area near corpus christi texas comprises two large coast parallel listric normal growth faults detached on mobilized shale like with most large gulf of mexico listric normal i e growth faults fault planes dip basinward accommodate large amounts of extension and link along strike with other growth faults less characteristically the hanging wall of the growth fault system comprises an elongate ridge whose strike is coast perpendicular and hence orthogonal to the growth faults a high angle coast perpendicular normal fault orthogonal to the growth faults nucleates on the roof of the ridge a model for the concomitant development of coast parallel and coast perpendicular ridges and faults is proposed to explain the development of the orthogonal fault first the early development of coast parallel and coast perpendicular ridges could have been related to convergent thin skinned shortening differential loading or a combination of the two second when large seaward translation occurred ridges having different orientations evolved differently those oriented parallel to the direction of maximum extension coast perpendicular were subjected to little or no extension conditions were thus set for a later nucleation of the orthogonal fault above the coast perpendicular ridge during a much later stage of extension in contrast ridges striking perpendicular to the direction of maximum extension coast parallel underwent collapse and acted as nucleation points for coast parallel growth faulting

creep of rocksalt abstract a review is presented of the fundamental flow properties and processes in experimentally deformed natural and synthetic halite single crystals and polycrystalline aggregates included in the summary are discussions of a microstructures induced during steady state creep b creep rupture of rocksalt c experiments associated with project salt vault and more recent field studies and d brine migration a representative steady state flow law determined for natural aggregates and maximum natural deviatoric stresses deduced from subgrain sizes are applied briefly to considerations of creep in waste repositories and of salt dome dynamics while the mechanical behavior of rocksalt is probably better understood than for all other rock types further investigations especially on load path stress history and creep rupture are clearly mandated furthermore additional investigations of brine migration and of bench and field scale deformations are needed the latter incorporating realistic rocksalt flow properties into numerical simulations of natural rock mass response

wave induced boundary layer separation in the lee of the medicine bow mountains part i observations abstracttwo cases of mountain waves rotors and the associated turbulence in the lee of the medicine bow mountains in southeastern wyoming are investigated in a two part study using aircraft observations and numerical simulations in part i observations from in situ instruments and high resolution cloud radar on board the university of wyoming king air aircraft are presented and analyzed measurements from the radar compose the first direct observations of wave induced boundary layer separation the data from these two events show some striking similarities but also significant differences in both cases rotors were observed yet one looks like a classical lee wave rotor while the other resembles an atmospheric hydraulic jump with midtropospheric gravity wave breaking aloft high resolution 30 30 m2 dual doppler syntheses of the two dimensional velocity fields in the vertical plane beneath the aircraft reveal the boundary layer separation the scale and structure of the attendant rotors and downsl

observational evidence of reemergence in the extratropical southern hemisphere observations of subsurface temperatures are used to examine the winter to winter reemergence of sea surface temperature sst anomalies in the extratropical south pacific ocean reemergence is the mechanism through which sst anomalies formed in the late winter are sequestered beneath the relatively shallow summer mixed layer and then reentrained into the deepening mixed layer during the following autumn winter although several studies have extensively examined reemergence in the northern hemisphere nh this is the first study to use observations of subsurface temperatures to document reemergence in the extratropical southern hemisphere sh the sh subsurface data reveal a pronounced reemergence signal in the western extratropical south pacific in this region surface thermal anomalies formed during late sh winter are observed to persist below the summertime mixed layer and reemerge at the surface during the followingearly winter months as such sst anomalies formed during late winter are strongly correlated with sst anomalies during the following early winter but are not significantly correlated with sst anomalies during the intervening summer months the results based on subsurface data are robust to small changes in the period of analysis and are qualitatively similar to existing evidence of reemergence in the nh analyses of independent sst data reveal that reemergence is widespread in the western extratropical south pacific basin but is less discernible in sst anomalies over the eastern part of the basin

winter to winter recurrence of sea surface temperature anomalies in the northern hemisphere the spatiotemporal characteristics of the winter to winter recurrence wwr of sea surface temperature anomalies ssta in the northern hemisphere nh are comprehensively studied through lag correlation analysis on this basis the relationships between the ssta wwr and the wwr of the atmospheric circu lation anomalies el nino southern oscillation enso and ssta interdecadal variability are also in vestigated results showthat the ssta wwr occurs over most parts of the north pacific and atlantic oceans but the spatiotemporaldistributionsofthesstawwraredistinctlydifferentinthesetwooceans analysesindicate that the spatiotemporal distribution of the ssta wwr in the north atlantic ocean is consistent with the spatial distribution of the seasonal cycle of its mixed layer depth mld whereas that in the north pacific ocean particularly the recurrence timing cannot be fully explained by the change in the mld between winterandsummerin someregions inaddition theatmospheric circulationanomaliesalsoexhibitthewwr at the mid high latitude of the nh which is mainly located in eastern asia the central north pacific and the north atlantic the sea level pressure anomalies slpa in the central north pacific are essential for the occurrenceofthesstawwrinthisregion moreover thestrongestpositivecorrelationoccurswhentheslpa lead ssta in the central northpacific by 1 month whichsuggeststhat the atmospheric forcingon the ocean may play a dominant role in this region therefore the reemergence mechanism is not the only process influ encing the ssta wwr and the wwr of the atmospheric circulation anomalies may be one of the causes of the ssta wwr in the central north pacific finally the occurrence of the ssta wwr in the nh is closely related to ssta interdecadal variability in the nh but it is linearly independent of enso

formation and subduction of central mode water based on profiling float data 2003 08 abstract temperature and salinity data from argo profiling floats in the north pacific during 2003 08 have been analyzed to study the structure of winter mixed layer north of the kuroshio extension and the subsurface potential vorticity distribution in the subtropical gyre in relation to the formation and subduction of the central mode water cmw in late winter two zonally elongated bands of deep mixed layer extend at 33 39 and 39 43 n from the east coast of japan to 160 w these correspond to the formation region of the lighter variety of cmw l cmw and that of the denser variety of cmw d cmw and the recently identified transition region mode water trmw respectively in the western part of the l cmw and d cmw trmw formation regions west of 170 e the winter mixed layer becomes deeper and lighter to the east i e to the downstream as a result the formed mode water is reentrained into the mixed layer in the farther east in the following winter and modified to the lighter water and is thus

foehn warming distributions in nonlinear and linear flow regimes a focus on the antarctic peninsula the structure of lee side warming during foehn events is investigated as a function of cross barrier flow regime linearity two contrasting cases of westerly flow over the antarctic peninsula ap are considered one highly nonlinear the other relatively linear westerly flow impinging on the ap provides one of the best natural laboratories in the world for the study of foehn owing to its maritime setting and the larsen c ice shelf lcis providing an expansive homogeneous and smooth surface on its east side numerical simulations with the met office unified model at 1 5 km grid size and aircraft observations are utilized in case a relatively weak southwesterly cross peninsula flow and an elevated upwind inversion dictate a highly nonlinear foehn event with mountain wave breaking observed the consequent strongly accelerated downslope flow leads to high amplitude warming and ice shelf melt in the immediate lee of the ap however this foehn warming diminishes rapidly downwind due to upward ascent of the foehn flow via a hydraulic jump in case c strong northwesterly winds dictate a relatively linear flow regime there is no hydraulic jump and strong foehn winds are able to flow at low levels across the entire ice shelf mechanically mixing the near surface flow preventing the development of a strong surface inversion and delivering large fluxes of sensible heat to the ice shelf consequently in case c ice melt rates are considerably greater over the lcis as a whole than in case a our results imply that although nonlinear foehn events cause intense warming in the immediate lee of mountains linear foehn events will commonly cause more extensive lee side warming and over an ice surface higher melt rates this has major implications for the ap where recent east coast warming has led to the collapse of two ice shelves immediately north of the lcis

reemergence areas of winter sea surface temperature anomalies in the world s oceans 1 using datasets of sea surface temperature sst surface heat flux upper ocean thermal data and climatological temperature and salinity profiles we try to detect reemergence areas of winter sst anomalies in the world s oceans and describe characteristics of these areas in terms of mixed layer depth mld annual mean heat flux and properties of waters formed in winter mixed layer eventually seven reemergence areas are found four in the northern hemisphere and three in the southern hemisphere all areas have a large seasonal variation of mld and are the regions where annual mean heat fluxes are relatively small except for two regions in the northern hemisphere in the viewpoint of water properties it is found that these areas correspond to the mode water formation regions subtropical mode waters of the indian ocean south pacific south atlantic north pacific and north atlantic and north pacific central and north atlantic subpolar mode waters

on the reemergence of north atlantic sst anomalies abstract the reemergence mechanism whereby temperature anomalies extending over the deep winter mixed layer are stored beneath the surface in summer and are reentrained into the mixed layer when it deepens again in the following autumn and winter is studied in the north atlantic using approximately 40 years of surface and subsurface data reemergence is found to be robust in the sargasso sea and the northeast atlantic regions where i the mixed layer is much deeper in winter than in summer ii currents are relatively weak and iii temperature anomalies are coherent over broad areas the two leading empirical orthogonal functions of north atlantic sst anomalies also exhibit strong reemergence signatures a novel application of empirical orthogonal function analysis to temperature anomalies in the time depth plane which also incorporates information from all grid points is shown to be an efficient and useful approach for detecting reemergence without dependence on specific spatial patterns or prio

lidar observations of a breaking mountain wave associated with extreme turbulence observations from a doppler lidar which are enhanced by stratospheric aerosols from mount pinatubo s eruption provide unique measurements of mountain waves over the rocky mountains including nearly instantaneous observations of wave breaking in the lower stratosphere the wave breaking is revealed by a flow reversal aloft that marks a localized critical layer created when the wave amplitude was great enough to cause overturning the altitude spatial scale and duration of this wave induced critical layer are documented the mountain waves led to turbulence affecting commercial aircraft including one accident in which a cargo jet lost an engine and part of a wing in extreme turbulence at the same time the lidar was making observations nearby although earlier observations of mountain wave drag assumed wave stationarity over 3 5 h significant changes over less than 2 h are documented here such nonstationarity could contribute to discrepancies remaining between observations and simulations of mountain wave drag

synthesis of salt tectonics in the southern north sea uk abstract a structural model encompassing the southern north sea basin west of the central graben has been developed this model consists of a rift system affecting the post salt section around the basin margin and a large area of detached compressional buckle folds within the basin this pattern is initially a response to gravity sliding of the post salt section on the salt within the basin during the late triassic to late jurassic a close relationship between the location and trend of the peripheral graben system and basement structures in the pre salt is noted pre jurassic extension across the peripheral graben systems was balanced by the sum of fault heaves at the pre salt rotliegend level and shortening across salt cored buckle folds in the post salt section salt pillows and swells passively infilled the cores of these gravity induced buckle folds cretaceous and tertiary inversion involved basin tilt and renewed movement on basin bounding basement faults notably reverse movements did not propagate from basement structures up into the peripheral graben systems the post salt sedimentary section experienced gravity spreading in response to inversion related uplift resulting in syn inversion extensional faulting in the sole pit high where the mesozoic section was thickest this extension combined with a loss of fault heave in the pre salt section was balanced by amplification of salt cored buckle folds in the centre of the basin in the context of the model described here salt pillows represent passive infill of thin skinned compressional buckle folds which later amplified during thick skinned basement shortening crestal collapse of such folds occurs via normal faulting accompanied by reactive diapirism such reactive diapirs establish conduits through which salt may leak leading to pillow deflation and ultimately conduit preservation as a salt wall flanked by rim synclines in areas where the buckle folds were emergent the salt structures described here are related to cover folds and faults which in turn reflect episodes of basin extension tilting and inversion hence individual salt structures can be said to be only remotely connected with regional intraplate stresses

on the persistence of decadal sst anomalies in the north atlantic abstract historical wintertime sea surface temperature sst data show that a sandwich pattern dominates on the decadal timescales in the north atlantic at least after the 1970s the authors investigated how such decadal sst anomalies can survive against local thermal feedback which acts to dampen them rapidly at the surface winter sst anomalies have a negligible projection with the subsequent summer anomalies while they show a significant projection with the sst anomalies in the next winter on the other hand observed summer temperature anomalies below the mixed layer tend to have the same sign as the previous winter sst anomalies although the magnitude of the former is roughly one third of the latter this suggests that a reemergence mechanism of sst anomalies associated with the seasonal cycle of the mixed layer depth mld which has been verified by alexander and deser helps maintain the decadal sst anomalies in order to examine this scenario a mixed layer model driven by daily atmospheric d

observations and numerical simulations of subrotor vortices during t rex high resolution observations from scanning doppler and aerosol lidars wind profiler radars as well as surface and aircraft measurements during the terrain induced rotor experiment t rex provide the first comprehensive documentation of small scale intense vortices associated with atmospheric rotors that form in the lee of mountainous terrain although rotors are already recognized as potential hazards for aircraft it is proposed that these small scale vortices or subrotors are the most dangerous features because of strong wind shear and the transient nature of the vortices a life cycle of a subrotor event is captured by scanning doppler and aerosol lidars over a 5 min period the lidars depict an amplifying vortex with a characteristic length scale of 500 1000 m that overturns and intensifies to a maximum spanwise vorticity greater than 0 2 s 1 radar wind profiler observations document a series of vortices characterized by updraft downdraft couplets and regions of enhanced reversed flow that are generated in a layer of strong vertical wind shear and subcritical richardson number the observations and numerical simulations reveal that turbulent subrotors occur most frequently along the leading edge of an elevated sheet of horizontal vorticity that is a manifestation of boundary layer shear and separation along the lee slopes as the subrotors break from the vortex sheet intensification occurs through vortex stretching and in some cases tilting processes related to three dimensional turbulent mixing the subrotors and ambient vortex sheet are shown to intensify through a modest increase in the upstream inversion strength which illustrates the predictability challenges for the turbulent characterization of rotors

remote reemergence areas of winter sea surface temperature anomalies in the north pacific 1 taking account of water movement we detect pairs of formation and reemergence areas of winter sea surface temperature sst anomalies in the north pacific by analyzing various kinds of data sets two pairs of formation and reemergence areas are detected one pair is located in the northern subtropical gyre and water properties in both the formation and reemergence areas well correspond to those of north pacific central mode water npcmw another pair is found in the western to central part of the subtropical gyre the formation area corresponds well to that of north pacific subtropical water npstmw but the reemergence area is remote from the formation area examinations on upper ocean current field trace of temperature anomalies in the subsurface and change of water properties from the formation area to the reemergence area clearly indicate that waters with winter sst anomalies move from the formation area to the reemergence area in a year

tectonic setting and stratigraphic architecture of an early cretaceous lacustrine carbonate platform sugar loaf high santos basin brazil abstract the sugar loaf high is an extensive basement structure within the santos basin offshore brazil in which all of the elements of the pre salt hydrocarbon play are present following a clastic dominated early synrift phase the later synrift and sag phases are characterized by an extensive non marine carbonate platform over the basement high the study area within this new 3d seismic dataset contains carbonates stratigraphically equivalent to the reservoirs within the lula and sapinhoa fields analysis of the 3d seismic data shows that the pre salt carbonates onlap the basement of the sugar loaf high and form aggradational geometries on a platform that has a proximal to distal width of about 100 km and an interpreted relief of some 900 m the carbonate platform has an aggradational and mounded basinward facing gullied margin with slope deposits progradational units are imaged on the platform top that may be either carbonate or clastic in composition the platform is preserved beneath evaporites that form the regional seal within the santos basin platforms of this size are previously unknown from lacustrine settings outside the pre salt stratigraphy of the santos and campos basins brazil

summertime evolution of decadal sea surface temperature anomalies in the midlatitude north pacific abstract to clarify the summertime evolution of decadal sea surface temperature sst anomalies and related physical processes in the midlatitudes of the north pacific numerical solutions of a three dimensional bulk mixed layer model are analyzed focusing on the contribution of the net shortwave radiative forcing at the sea surface a quantitative heat budget analysis for the ocean mixed layer relating to late 1980s decadal sst change reveals that the decadal sst anomalies decay from late spring to early summer over the entire midlatitudes of the north pacific this quasi seasonal decay of the decadal sst anomalies is controlled by an anomalous local thermal damping i e anomalous surface heat fluxes from midsummer to early autumn the anomalous net shortwave radiation flux associated with a meridional shift of the storm track acts to induce strong seasonal damping of the decadal sst anomaly in the northern kuroshio oyashio extension region in contrast in the north of the subtropical frontal region

large amplitude mountain wave breaking over greenland abstract a large amplitude mountain wave generated by strong southwesterly flow over southern greenland was observed during the fronts and atlantic storm track experiment fastex on 29 january 1997 by the noaa g iv research aircraft dropwindsondes deployed every 50 km and flight level data depict a vertically propagating large amplitude wave with deep convectively unstable layers potential temperature perturbations of 25 k that deformed the tropopause and lower stratosphere and a vertical velocity maximum of nearly 10 m s 1 in the stratosphere the wave breaking was associated with a large vertical flux of horizontal momentum and dominated by quasi isotropic turbulence the coupled ocean atmosphere mesoscale prediction system coamps nonhydrostatic model with four nested grid meshes with a minimum resolution of 1 7 km accurately simulates the amplitude location and timing of the mountain wave and turbulent breakdown finescale low velocity plumes that resemble wakelike structures emanate from highl

large scale boudinage of late miocene platform series triggered by margin collapse during the messinian salinity crisis ibiza island spain abstract in ibiza island we show for the first time that the post tectonic late miocene deposits are locally deformed in synsedimentary large scale boudinage structures the late miocene series is composed of a carbonate rich unit 1 that is overlaid by a clastic unit 2 and a unit 3 in which a basal oolite rich deposit is distinguished from an upper stromatolite rich part the oolite rich and competent layers of unit 3 are dissected into large rectangular to barrel shape boudins that indicate a multidirectional extension the separation of the blocks develops significantly northward revealing a stretching increase in a seaward direction that could have been favored by sliding of the distal part of the underlying marly unit over the clays along and in between the boudins the laminated layers form soft sediment syncline folds the progressive bending of these laminated layers created spaces that were filled with calcite crystal wedges providing evidence for large fluid circulation during deformation microthermometry on fluid inclusions in these calcite crystals revealed growth temperatures ranging from 190 to 260 c this high recrystallization rate is an indication of important fluid circulation during deformation processes besides the progressive infill of paleosols over some of the synsedimentary synclines indicates that deformation was a slow process during the emersion of the series and the subaerial messinian channels location in the topographic depressions formed by the boudinage of the late miocene series confirms that the deformation and sliding occurred during the relative emersion associated with the messinian salinity crisis we thus interpret the boudinage as resulting from the destabilization of a still soft carbonate platform whose sliding has been helped substantially by the injection of relatively hot fluids this work provides an onland evidence for extensional collapse during the messinian sea level drawdown

a mechanism for the recurrence of wintertime midlatitude sst anomalies abstract in the early 1970s namias and born speculated that ocean temperature anomalies created over the deep mixed layer in winter could be preserved in the summer thermocline and reappear at the surface in the following fall or winter this hypothesis is examined using upper ocean temperature observations and simulations with a mixed layer model the data were collected at six ocean weather stations in the north atlantic and north pacific concurrent and lead lag correlations are used to investigate temperature variations associated with the seasonal cycle in both the observations and the model simulations concurrent correlations between the surface and subsurface temperature anomalies in both the data and the model indicate that the penetration of temperature anomalies into the ocean is closely tied to the seasonal cycle in mixed layer depth high correlations extend to relatively deep shallow depths in winter summer lead lag correlations in both the data and the model at some of the stations

the subpolar mode water of the north atlantic ocean abstract the warm waters of the subtropical and subpolar basins of the north atlantic have tight regional temperature salinity relationships and are conventionally called the regional central waters a volumetric census of the temperature salinity characteristics of the north atlantic by wright and worthington 1970 shows that waters characterized by certain segments of the t s relationships have large volumes compared to those of other segments volumetric mode waters such mode waters appear as layers with increased vertical separation between isopycnals pycnostads the present study reports on the existence of pycnostads in the central and eastern north atlantic these subpolar mode waters are formed by deep winter convection in the subpolar north atlantic and participate in the upper water circulation of the northern north atlantic the seasonal outcropping of the pycnostads occurs within and adjacent to the north atlantic current the irminger current the east and west greenland currents and

mountain wave turbulence in the presence of directional wind shear over the rocky mountains abstractmountain wave turbulence in the presence of directional wind shear over the rocky mountains in colorado is investigated pilot reports pireps are used to select cases in which moderate or severe turbulence encounters were reported in combination with significant directional wind shear in the upstream sounding from grand junction colorado gjt for a selected case semi idealized numerical simulations are carried out using the wrf arw atmospheric model initialized with the gjt atmospheric sounding and a realistic but truncated orography profile to isolate the role of directional wind shear in causing wave breaking sensitivity tests are performed to exclude the variation of the atmospheric stability with height the speed shear and the mountain amplitude as dominant wave breaking mechanisms significant downwind transport of instabilities is detected in horizontal flow cross sections resulting in mountain wave induced turbulence occurring at large horizontal distances from the first wave br

wintertime shoaling of oceanic surface mixed layer 1 wintertime oceanic surface mixed layer has been believed to deepen due to cooling and wind stirring however it is shown that in the latitudes of 20 30 in the world ocean there are regions where wintertime oceanic surface mixed layer shoals the mixed layer shoaling is mostly accompanied by sea surface temperature sst cooling from january to february from july to august and sst warming from february to march from august to september in the northern southern hemisphere ocean further studies on the evolution of the mixed layer in these areas are suggested as these shoaling phenomena cannot be explained by existing theories of oceanic mixed layer based on monthly surface flux data

gravity wave breaking over the central alps role of complex terrain abstract the characteristics of gravity waves excited by the complex terrain of the central alps during the intensive observational period iop 8 of the mesoscale alpine programme map is studied through the analysis of aircraft in situ measurements gps dropsondes radiosondes airborne lidar data and numerical simulations mountain wave breaking occurred over the central alps on 21 october 1999 associated with wind shear wind turning and a critical level with richardson number less than unity just above the flight level 5 7 km of the research aircraft ncar electra the electra flew two repeated transverses across the otztaler alpen during which localized turbulence was sampled the observed maximum vertical motion was 9 m s 1 corresponding to a turbulent kinetic energy tke maximum of 10 5 m2 s 2 spectrum analysis indicates an inertia subrange up to 5 km wavelength and multiple energy containing spikes corresponding to a wide range of wavelengths manual analysis of gps dropsonde data indic

turbulence in breaking mountain waves and atmospheric rotors estimated from airborne in situ and doppler radar measurements atmospheric turbulence generated in flow over mountainous terrain is studied using airborne in situ and cloud radar measurements over the medicine bow mountains in southeast wyoming usa during the nasa orographic clouds experiment nasa06 in 2006 two complex mountain flow cases were documented by the university of wyoming king air research aircraft carrying the wyoming cloud radar the structure of turbulence and its intensity across the mountain range are described using the variance of vertical velocity w2 and the cube root of the energy dissipation rate 1 3 edr for a quantitative analysis of turbulence from the cloud radar the uncertainties in the doppler wind retrieval have to be taken into account such as the variance of hydrometeor fall speed and the contamination of vertical doppler velocity by the horizontal wind a thorough analysis of the uncertainties shows that 25 accuracy or better can be achieved in regions of moderate to severe turbulence in the lee of the mountains while only qualitative estimates of turbulence intensity can be obtained outside the most turbulent regions two nasa06 events exhibiting large amplitude mountain waves mid tropospheric wave breaking and rotor circulations are examined moderate turbulence is found in a wave breaking region with w2 and edr reaching 4 8 m2 s 2 and 0 25 m2 3 s 1 respectively severe turbulence is measured within the rotor circulations with w2 and edr respectively in the ranges of 7 8 16 4 m2 s 2 and 0 50 0 77 m2 3 s 1 a unique result of this study is the quantitative estimation of the intensity of turbulence and its spatial distribution in the interior of atmospheric rotors provided by the radar derived turbulence fields

subtropical mode waters in the south atlantic ocean this systematic study of the subtropical mode waters in the south atlantic is based on hydrological data the basin wide south atlantic ventilation experiment oceanus and ajax sections and the world ocean circulation experiment woce sections in the brazil malvinas confluence region the woce expendable bathythermograph data set and the atmospheric forcing produced by the national centers for environmental prediction reanalysis the main ventilation window of the subtropical gyre lies in the southwest and corresponds to the southern part of the recirculation region and to the overshoot of the brazil current bc some ventilation occurs along the southern branch of the gyre through deep mixed layers in harsh winters and in the east through the rings shed by the agulhas current however the ventilation from the eastern border concerns a small volume of water with highly variable characteristics three main types of subtropical mode water are observed the lightest around the 26 2 density surface and the second and third around the 26 5 and 26 7 density surfaces respectively the 26 2 subtropical mode water stmw1 corresponds to potential temperatures between 16 and 18 c and salinities between 35 9 and 36 2 the stmw1 thickness does not exceed 150 m the volume of the 26 5 mode water stmw2 is larger it is produced through the formation of deep mixed layers reaching 300 m or more in the active ventilation window over the bc overshoot its potential temperature ranges between 14 and 16 c and its salinity ranges between 35 5 and 35 9 its thickness can be above 300 m the last component observed around the 26 7 density surface stmw3 has a potential temperature between 12 and 14 c and a salinity of about 35 2 to 35 5 it is formed on the eastern flank of the bc overshoot and during harsh winters in the center of the southern branch of the gyre within the main ventilation window the stmws exhibit quite a significant variability in characteristics and volume there is a large interannual variability in the atmospheric forcing over the bc recirculation and bc extension and the observed variations of the subtropical mode waters are qualitatively correlated to the atmospheric forcing variations