diurnal evolution of submesoscale front and filament circulations abstractthe local circulation of submesoscale fronts and filaments can be partly understood through a horizontal momentum balance of coriolis a horizontal pressure gradient and vertical diffusivi

dynamics of wind forced coherent anticyclones in the open ocean we numerically study the dynamics of coherent anticyclonic eddies in the ocean interior for the hydrostatic rotating stably stratified turbulence we use a high resolution primitive equation model forced by small scale winds in an idealized configuration many properties of the horizontal motions are found to be similar to those of two dimensional and quasi geostrophic turbulence major differences are a strong cyclone anticyclone asymmetry linked to the straining field exerted by vortex rossby waves which is also found in shallow water flows and the complex structure of the vertical velocity field which we analyze in detail locally the motion can become strongly ageostrophic and vertical velocities associated with vortices can reach magnitudes and levels of spatial complexity akin to those reported for frontal regions transport and mixing properties of the flow field are further investigated by analyzing lagrangian trajectories particles released in the pycnocline undergo large vertical excursions because of the vertical velocities associated to the vortices with potentially important consequences for marine ecosystem dynamics

the role of horizontal divergence in submesoscale frontogenesis abstractoceanic surface submesoscale currents are characterized by anisotropic fronts and filaments with widths from 100 m to a few kilometers an o 1 rossby number and large magnitudes of latera

enhanced turbulence and energy dissipation at ocean fronts the ocean surface boundary layer mediates air sea exchange in the classical paradigm and in current climate models its turbulence is driven by atmospheric forcing observations at a 1 kilometer wide front within the kuroshio current indicate that the rate of energy dissipation within the boundary layer is enhanced by one to two orders of magnitude suggesting that the front rather than the atmospheric forcing supplied the energy for the turbulence the data quantitatively support the hypothesis that winds aligned with the frontal velocity catalyzed a release of energy from the front to the turbulence the resulting boundary layer is stratified in contrast to the classically well mixed layer these effects will be strongest at the intense fronts found in the kuroshio current the gulf stream and the antarctic circumpolar current all of which are key players in the climate system

drifter observations of submesoscale flow kinematics in the coastal ocean fronts and eddies identified with aerial guidance are seeded with drifters to quantify submesoscale flow kinematics the lagrangian observations show mean divergence and vorticity values that can exceed five times the coriolis frequency values are the largest observed in the field to date and represent an extreme departure from geostrophic dynamics the study also quantifies errors and biases associated with lagrangian observations of the underlying velocity strain tensor the greatest error comes from under sampling even with a large number of drifters a significant bias comes from inhomogeneous sampling of convergent regions that accumulate drifters within a few hours of deployment the study demonstrates a lagrangian sampling paradigm for targeted submesoscale structures over a broad range of scales and presents flow kinematic values associated with vertical velocities o 10 m h 1 that can have profound implications on ocean biogeochemistry

high latitude lower thermospheric neutral winds at eiscat and sondrestrom during ltcs 1 the incoherent scatter radar located at sondre stromfjord greenland 67 n 51 w 74 5 and the eiscat incoherent scatter facility located in northern scandinavia 69 5 n 19 e 66 3 both obtained e and f region measurements during the first campaign of the lower thermosphere coupling study ltcs 1 september 21 25 1987 neutral winds deduced from these measurements have been analyzed for their mean flow and tidal components a number of the altitude profiles for the mean winds and the diurnal and semidiurnal wave components at the two radar locations show similar variations with height indicating that latitudinal rather than longitudinal effects are dominant in determining the observed wind field diurnal tidal amplitudes and phases are reasonably well represented by theoretical model results forbes 1982 the semidiurnal amplitudes and phases although somewhat consistent between the two radars are not well represented in equinox tidal model results forbes and vial this issue results from both radars indicate a vertical wavelength for the zonal semidiurnal oscillation of approximately 60 km during a period of impulsive magnetospheric forcing september 22 23 winds deduced from measurements at both radars show enhanced eastward flows near midnight accompanied by equatorward winds at sondrestrom comparison with the results of a national center for atmospheric research thermosphere ionosphere general circulation model tigcm simulation of the ltcs 1 interval shows generally better agreement with the observations at eiscat than at sondrestrom during the period of activity on september 22 23 the tigcm is reasonably successful at simulating the eastward surge near midnight in the eiscat but not in the sondrestrom observations and the equatorward flow after midnight in the sondrestrom results the observed winds in magnetic latitude and magnetic local time coordinates indicate the presence of anticyclonic divergent flow near dusk and cyclonic converging flow near dawn

observations of the two day wave in windii data during january 1993 analysis of variations in the zonal and meridional wind observed by the wind imaging interferometer windii on the upper atmosphere research satellite uars from january 19 to january 31 1993 reveal a strong quasi two day wave qtdw signature these observations were taken during the time of peak amplitude for this qtdw event wu et al 1993 and extend from 41 n to 71 s daytime and nighttime results are presented for the altitude ranges 90 to 150 km and 90 to 102 km respectively the qtdw is found to occur with significant amplitude well into the winter hemisphere and lower thermosphere its latitudinal structure below 103 km is found to be similar to that calculated by hagan et al 1993 using the background wind profile of portniagin and solov yeva 1992 the peak amplitude occurs at 94 km with a magnitude of about 50 m s for the meridional wind and 30 m s for the zonal wind mean profiles from the summer midlatitudes show a secondary maximum in amplitude near 115 km and a node at 130 km above 130 km the wave appears to be evanescent

friction frontogenesis and the stratification of the surface mixed layer the generation and destruction of stratification in the surface mixed layer of the ocean is understood to result from vertical turbulent transport of buoyancy and momentum driven by air sea fluxes and stresses in this paper it is shown that the magnitude and penetration of vertical fluxes are strongly modified by horizontal gradients in buoyancy and momentum a classic example is the strong restratification resulting from frontogenesis in regions of confluent flow frictional forces acting on a baroclinic current either imposed externally by a wind stress or caused by the spindown of the current itself also modify the stratification by driving ekman flows that differentially advect density ekman flow induced during spindown always tends to restratify the fluid while wind driven ekman currents will restratify or destratify the mixed layer if the wind stress has a component up or down front i e directed against or with the geostrophic shear respectively scalings are constructed for the relative importance of friction versus frontogenesis in the restratification of the mixed layer and are tested using numerical experiments of mixed layer fronts forced by both winds and a strain field the scalings suggest and the numerical experiments confirm that for wind stress magnitudes mixed layer depths and cross front density gradients typical of the ocean wind induced friction often dominates frontogenesis in the modification of the stratification of the upper ocean the experiments reveal that wind induced destratification is weaker in magnitude than restratification because the stratification generated by up front winds confines the turbulent stress to a depth shallower than the ekman layer which enhances the frictional force ekman flow and differential advection of density frictional destratification is further reduced over restratification because the stress associated with the geostrophic shear at the surface tends to compensate a down front wind stress

eliassen palm fluxes of the 2 day wave abstract high resolution doppler imager hrdi winds and temperatures are used to diagnose a 2 day wave event detected in the southern hemisphere during january 1994 a novel aspect of this study is the focus upon the wave fluxes throughout the 65 100 km range and their relationship to the background state a wave packet composed of zonal wavenumbers 2 3 and 4 propagates westward with a phase speed near 60 m s 1 the periods associated with zonal wavenumbers 2 3 and 4 are 3 5 2 1 and 1 7 days respectively the morphology of the 2 day temperature and wind fields is consistent with that of a developing baroclinic wave the divergence of the eliassen palm flux of zonal wavenumbers 2 4 is dominated by the vertical convergence of meridional heat flux the wave driving or eliassen palm flux divergence per unit mass is predominantly westward with magnitudes on the order of 5 m s 1 day 1 a steady state quasigeostrophic model of the mean meridionai circulation is used to estimate the mean wind respon

diagnosing lateral mixing in the upper ocean with virtual tracers spatial and temporal resolution dependence several recent studies diagnose lateral stirring and mixing in the upper ocean using altimetry derived velocity fields to advect virtual particles and fields offline however the limited spatiotemporal resolution of altimetric maps leads to errors in the inferred diagnostics because unresolved scales are necessarily imperfectly modeled the authors examine a range of tracer diagnostics in two models of baroclinic turbulence the standard phillips model in which dispersion is controlled by large scale eddies and the eady model where dispersion is determined by local scales of motion these models serve as a useful best and worst case comparison and a valuable test of the resolution sensitivity of tracer diagnostics the effect of unresolved scales is studied by advecting tracers using model velocity fields subsampled in space and time and comparing the derived tracer diagnostics with their true value obtained from the fully resolved flow the authors find that eddy diffusivity and absolute dispersion which are governed by largescaledynamics areinsensitivetospatialsamplingerrorin eitherflow measuresthatdependstronglyonsmall scales such as relative dispersion andfinite timelyapunov exponents are highly sensitive to spatial sampling in the eady model temporal sampling error is found to have a more complicated behavior because of the onset of particle overshoot leading to scrambling of lagrangian diagnostics this leads to a potential restrictionontheutilityofrawaltimetrymapsforstudyingmixingintheupperocean theauthorsconcludethat offline diagnostics of mixing in ocean flows with an energized submesoscale should be viewed with some caution

pattern formation at the ocean surface sargassum distribution and the role of the eddy field positively buoyant organisms such as the macroalga sargassum and the cyanobacterium trichodesmium often form surface accumulations visible in satellite imagery that have lateral scale separation of tens of kilometers and cannot be explained by langmuir circulation here we discuss the accumulation of floating materials in the ocean in presence of meso and submesoscale activity using high resolution simulations of the ocean mesoscale in both idealized a 3 dimensional box where coherent eddies are forced by small scale winds and realistic domains western gulf of mexico where extensive concentrations of floating sargassum have been recorded in satellite images we show that the distribution of tracers at the ocean surface departs rapidly from that observed a few tens of meters below it such distribution does not resemble that observed for passive tracers in quasi geostrophic turbulence the strong divergence and convergence zones generated at the surface by ageostrophic processes in the submesoscale range are responsible for the creation of areas where the floating material accumulates floating particles are expelled from the core of mesoscale eddies and concentrate in convergence regions in patterns comparable to the ones observed through the satellite images in light of those results sargassum and or trichodesmium may provide a useful proxy to track convergence divergence processes resulting from ageostrophic processes at the ocean surface

ocean convergence and the dispersion of flotsam floating oil plastics and marine organisms are continually redistributed by ocean surface currents prediction of their resulting distribution on the surface is a fundamental long standing and practically important problem the dominant paradigm is dispersion within the dynamical context of a nondivergent flow objects initially close together will on average spread apart but the area of surface patches of material does not change although this paradigm is likely valid at mesoscales larger than 100 km in horizontal scale recent theoretical studies of submesoscales less than 10 km predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices here we show that such structures can dramatically concentrate floating material more than half of an array of 200 surface drifters covering 20 20 km2 converged into a 60 60 m region within a week a factor of more than 105 decrease in area before slowly dispersing as predicted the convergence occurred at density fronts and with cyclonic vorticity a zipperlike structure may play an important role cyclonic vorticity and vertical velocity reached 0 001 s 1 and 0 01 ms 1 respectively which is much larger than usually inferred this suggests a paradigm in which nearby objects form submesoscale clusters and these clusters then spread apart together these effects set both the overall extent and the finescale texture of a patch of floating material material concentrated at submesoscale convergences can create unique communities of organisms amplify impacts of toxic material and create opportunities to more efficiently recover such material

submesoscale evolution of surface drifter triads in the gulf of mexico triangle shape metrics are analyzed to quantify the evolution of submesoscale 100 500 m initial separation surface drifter triplets released in the northern gulf of mexico the observations are compared to synthetic drifters advected by geostrophic velocity fields derived from satellite altimetry observed submesoscale triads evolve rapidly reaching highly elongated configurations on timescales of 6 hours to 2 days in contrast to 6 days or longer for altimetry derived synthetic data estimates of horizontal divergence and strain rate from the drifter triplets indicate the relative importance of divergence in the evolution of triangle shape horizontal divergence is scale dependent on the order of the local coriolis parameter and 2 to 3 times larger for initial 100 m scales compared to initial 500 m scales

the quasi 2 day wave observed in the polar mesosphere 1 using mf radar data obtained at tromso 69 6 n 19 2 e for 37 months between 1 november 1998 and 8 december 2001 we have examined characteristics of the quasi 2 day wave q2dw in the polar mesosphere in the height range from 70 to 91 km the activity of the q2dw is higher in winter months november february than in summer months may august over this height region the maximum values of the amplitude are 25 m s 1 in winter and 15 m s 1 in summer between 70 and 82 km the amplitude appears to maximize near winter solstice over the 3 years the average ratio of meridional to zonal amplitudes is 1 1 1 2 over the height region thus there is no significant preference towards either components the variations of the periods of maximum amplitude are also examined and periods with 45 2 and 54 9 hours occur more frequently than those with 48 0 and 51 2 hours however no clear seasonal trend of the variation of the period is found in addition the amplitude is modulated at 4 10 day rate with simultaneous observational data from the mf radar and the eiscat uhf radar colocated in tromso we have examined whether or not the q2dw was able to penetrate to the lower thermosphere for the period of 1 9 july 1999 it is found that the amplitude of the q2dw with period of 51 2 hours maximized at 95 km height with values of 25 m s 1 in both meridional and zonal components the q2dw was attenuated above 95 km but it appears to survive up to 108 km height in the meridional component between 85 and 95 km for the meridional component during this 8 day interval the q2dw and semidiurnal tide were the strongest among the periodic components

mean winds tides and quasi 2 day wave in the polar lower thermosphere observed in european incoherent scatter eiscat 8 day run data in november 2003 1 simultaneous european incoherent scatter eiscat radar observations using two eiscat radars the tromso 69 6 n 19 2 e uhf radar and the eiscat svalbard radar longyearbyen 78 2 n 16 0 e were conducted for 8 consecutive days from 11 to 19 november 2003 to study the lower thermospheric wind dynamics in the polar region altitude profiles of the amplitudes of the diurnal and semidiurnal components at tromso and longyearbyen are similar the semidiurnal amplitudes in the meridional and zonal components exhibit maxima at 105 107 km with values of 70 90 m s 1 the semidiurnal phases vary with roughly a 30 km vertical wavelength between 98 and 110 km the quasi 2 day wave q2dw was not detected in the lower thermosphere at either tromso or longyearbyen during the period while it was found between 70 and 82 km in the mesosphere with the colocated tromso mf radar this observational result suggests that in general the q2dw attenuates in the mesosphere and cannot penetrate into the lower thermosphere in winter ion drag acceleration of the wind is generally negligible below 107 km at tromso and below 118 km at longyearbyen but significant ion drag acceleration is found above these heights a comparison of mean wind and tidal amplitudes and phases with national center for atmospheric research thermosphere ionosphere mesosphere electrodynamics general circulation model predictions for the period shows some agreement

an eastward propagating two day wave evidence for nonlinear planetary wave and tidal coupling in the mesosphere and lower thermosphere 1 temperature observations from the saber instrument on the timed spacecraft are used to investigate the structure and evolution of an eastward propagating zonal wavenumber 2 disturbance with a period near two days this oscillation obtains a maximum amplitude of nearly 10 k in the southern hemisphere mid latitudes during late january the timing and location of this planetary wave is coincident with the regular quasi two day wave intensification that occurs annually in late january the period wavenumber and spatial structure of the eastward propagating two day wave are consistent with a wave that results from a nonlinear interaction between the quasi two day wave and the migrating diurnal tide the existence of an eastward propagating wave with a period near two days coincident with the westward propagating two day wave will have an impact on the interpretation of ground based observations analysis of the saber temperature observations are utilized to determine the structure and evolution of both this eastward propagating two day wave and the classic westward propagating zonal wavenumber 3 quasi two day wave during january 2005

diurnal cycling of submesoscale dynamics lagrangian implications in drifter observations and model simulations of the northern gulf of mexico abstractthe diurnal cycling of submesoscale circulations in vorticity divergence and strain is investigated using drifter data collected as part of the lagrangian submesoscale experiment laser

submesoscale cold filaments in the gulf stream abstracta set of realistic very high resolution simulations is made for the gulf stream region using the oceanic model regional oceanic modeling system roms to study the life cycle of the intense submesoscale cold filaments that form on the subtropical gyre interior wall of the gulf stream the surface buoyancy gradients and ageostrophic secondary circulations intensify in response to the mesoscale strain field as predicted by the theory of filamentogenesis it can be understood in terms of a dual frontogenetic process along the lines understood for a single front there is however a stronger secondary circulation due to the amplification at the center of a cold filament filament dynamics in the presence of a mixed layer are not adequately described by the classical thermal wind balance the effect of vertical mixing of momentum due to turbulence in the surface layer is of the same order of magnitude as the pressure gradient and coriolis force and contributes equally to a so called turbulent therm

a simple analytical model of the diurnal ekman layer abstractthe effects of time varying turbulent viscosity on horizontal currents in the ocean surface boundary layer are considered using a simple theoretical model that can be solved analytically this model reproduces major aspects of the near surface ocean diurnal cycle in velocity and shear while retaining direct parallels to the steady state ekman solution the parameter dependence of the solution is explored and quantitative measures of the low frequency rectification of velocity and shear are derived results demonstrate that time variability in eddy viscosity leads to significant changes to the time averaged velocity and shear fields with important implications for the interpretation of observations and modeling of the near surface ocean these findings mirror those of more complete numerical modeling studies suggesting that some of the rectification mechanisms active in those studies may be independent of the details of the boundary layer turbulence

submesoscale impacts on horizontal and vertical transport in the gulf of mexico 1 impacts of submesoscale processes on transport are investigated numerically in an energetic mesoscale flow with an ocean model run at two horizontal resolutions 1 and 5 km the focus is the northwestern gulf of mexico where the loop current eddies are surrounded by smaller vortices by increasing the horizontal resolution the number and strength of submesoscale eddies and vorticity filaments within the mixed layer increase dramatically and with them the vertical velocities inside the coherent eddies and at their peripheries increased vertical velocities for increasing resolution are associated to near inertial motions and they are not limited to the mixed layer but are found at all depths horizontal velocities on the contrary are similar lagrangian isobaric tracers are deployed close to the surface and at 100 m and three dimensional neutrally buoyant particles are released close to the surface at the base of the mixed layer and at 100 m the modeled horizontal dispersion curves for each deployment depth are independent of the kind of particles and of horizontal resolution close to the ocean surface however convergence zones generated by submesoscale ageostrophic motions and resolved at 1 km resolution influence the details of the tracer distributions vertical dispersion increases by several folds for increasing resolution at all depths explored with the largest differences found close to the surface therefore submesoscales processes play a fundamental role in driving vertical transport in eddy dominated flows both within and below the mixed layer for times comparable to the eulerian time scale

observations of near surface current shear help describe oceanic oil and plastic transport plastics and spilled oil pose a critical threat to marine life and human health as a result of wind forcing and wave motions theoretical and laboratory studies predict very strong velocity variation with depth over the upper few centimeters of the water column an observational blind spot in the real ocean here we present the first ever ocean measurements of the current vector profile defined to within 1 cm of the free surface in our illustrative example the current magnitude averaged over the upper 1 cm of the ocean is shown to be nearly four times the average over the upper 10 m even for mild forcing our findings indicate that this shear will rapidly separate pieces of marine debris which vary in size or buoyancy making consideration of these dynamics essential to an improved understanding of the pathways along which marine plastics and oil are transported

an ion drag contribution to the lower thermospheric wind in the summer polar region 1 using the european incoherent scatter eiscat svalbard radar located in longyearbyen 78 2 n 16 0 e and with the eiscat uhf radar located in tromso 69 6 n 19 2 e we have analyzed the data obtained for six consecutive days from 1000 ut on 1 july 1999 to 1000 ut on 7 july 1999 to investigate the importance of ion drag on the lower thermospheric wind dynamics in the summer polar region the electric field observed at longyearbyen exhibited a stable diurnal variation primarily occurring throughout the first 3 days of observations while during the latter 3 days the diurnal variation was not clearly identified the electric field observed at tromso did not exhibit such a stable variation on the basis of the difference of the electric field variation observed at longyearbyen we divided the data sets into two intervals with a length of 3 days each we compared the horizontal velocities of the ions and the neutral gases at upper heights 110 120 km on the first 3 days the difference between the ion and neutral motion was clearly identified at longyearbyen while it was not at tromso we compared the diurnal tidal amplitudes and phases of the two intervals derived from the longyearbyen data the amplitude of the meridional diurnal tide for the first 3 days was larger than that of the latter 3 days over the height region between 100 and 118 km at longyearbyen furthermore we compared ion drag accelerations with total accelerations we concluded that the ion drag played an important role in the diurnal amplitude at longyearbyen on the first 3 days of the observations in addition we compared the national center for atmospheric research thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm predictions with the observations the time gcm predictions also indicated that the diurnal tide is influenced by the convection electric field

eiscat observations of the e region semidiurnal tide many observers have reported a semidiurnal tide in the e region of the ionosphere1 7 theory demonstrates the possibility of several tidal modes with the relative strength of each mode depending on the efficiency of generation in the stratosphere the attenuation suffered in propagating through the mesosphere and mode coupling in regions of nonlinearity to determine which modes actually occur it is important to observe the tide at all heights in the e region and at a range of latitudes eiscat the european incoherent scatter radar2 3 is an ideal facility to make such observations at 69 5 n at this latitude measurements are usually perturbed by strong auroral heating but near sunspot minimum auroral disturbances are sometimes very small and the underlying pattern of the semidiurnal tides can be observed such conditions occurred in 1985 and here we report observations on five different days that illustrated the dominance of the 2 4 mode at high latitudes

origin of dolostone reservoir rocks smackover formation oxfordian northeastern gulf coast u s a formation of regionally extensive dolostone reservoir rocks in the smackover can be understood despite the possible effects of recrystallization geochemical and petrographic data suggest that dolomitization took place in 1 seawater seepage 2 reflux 3 near surface mixed water 4 shallow burial mixed water and 5 deeper burial environments which overlapped in time and space to form a platform scale dolostone body composed of a complex mixture of dolomites seawater seepage and reflux dolomitization occurred in the near surface penecontemporaneously with deposition of the smackover and overlying haynesville formations dolomitization by seawater seepage occurred within an oolite grainstone sill which separated an intraplatform salt basin from the open sea seawater flowed landward through the sill in response to evaporitic drawdown of brines in the isolated intraplatform basin isolation of the salt basin occurred during the oxfordian when the shoreline retreated from the conecuh embayment dolomite located at the top of the smackover enriched in 18 o suggests additional dolomitization by reflux of hypersaline brines reflux occurred as buckner coastal sabkhas prograded over smackover oolite grainstone shoreface deposits vugs lined with shallow burial calcite and dolomite cements indicate flushing of the smackover grainstone aquifer with fresh water freshwater intrusion probably occurred following sea level lowstands during the late jurassic and early cretaceous leaching in the proximal portion of the freshwater aquifer produced excellent limestone reservoir rocks in the updip smackover dolomitization in the contemporaneous downdip mixed connate freshwater zone formed dolostone reservoir rocks with depleted isotopic compositions consistent with a shallow burial mixed water origin

frontogenesis and frontal arrest of a dense filament in the oceanic surface boundary layer the evolution of upper ocean currents involves a set of complex poorly understood interactions between submesoscale turbulence e g density fronts and filaments and coherent vortices and smaller scale boundary layer turbulence here we simulate the lifecycle of a cold dense filament undergoing frontogenesis in the presence of turbulence generated by surface stress and or buoyancy loss this phenomenon is examined in large eddy simulations with resolved turbulent motions in large horizontal domains using sim 10 10 grid points steady winds are oriented in directions perpendicular or parallel to the filament axis due to turbulent vertical momentum mixing cold filaments generate a potent two celled secondary circulation in the cross filament plane that is frontogenetic sharpens the cross filament buoyancy and horizontal velocity gradients and blocks ekman buoyancy flux across the cold filament core towards the warm filament edge within less than a day the frontogenesis is arrested at a small width approx 100 text m primarily by an enhancement of the turbulence through a small submesoscale horizontal shear instability of the sharpened filament followed by a subsequent slow decay of the filament by further turbulent mixing the boundary layer turbulence is inhomogeneous and non stationary in relation to the evolving submesoscale currents and density stratification the occurrence of frontogenesis and arrest are qualitatively similar with varying stress direction or with convective cooling but the detailed evolution and flow structure differ among the cases thus submesoscale filament frontogenesis caused by boundary layer turbulence frontal arrest by frontal instability and frontal decay by forward energy cascade and turbulent mixing are generic processes in the upper ocean

tidal waves in the polar lower thermosphere observed using the eiscat long run data set obtained in september 2005 1 characteristics are presented of the lower thermospheric wind from a long run data set obtained by the eiscat uhf radar at tromso 69 6 n 19 2 e over 23 days from september 6 to 29 2005 the derived semidiurnal amplitude exhibited day to day variations 5 30 ms 1 at and above 109 km while the phase varied little with the day we have found a mode change of the semidiurnal tide occurring during september 17 22 2005 between september 6 and 16 the vertical wavelengths were estimated to be 58 km and 76 km for the meridional and zonal components respectively while between september 23 and 29 they became less than 24 km the day to day variability of the diurnal tide was less obvious than that of the semidiurnal tide the diurnal amplitude of the meridional component increased with height except for 8 days between september 13 and 20 when the diurnal amplitudes were smaller values 40 ms 1 at and above 111 km than those for the other intervals furthermore the shapes of the altitude profiles of the meridional phase differ from those for the other intervals we have evaluated contributions due to the electric field and the ion drag acceleration and showed that they were not the causes from the analysis of 22 5 days of wind data we found about 5 6 day oscillations in the lower thermosphere probably where there were planetary wave activities in the lower thermosphere

wind waves and fronts frictional effects in a generalized ekman model abstractocean currents in the surface boundary layer are sensitive to a variety of parameters not included in classic ekman theory including the vertical structure of eddy viscosity finite boundary layer depth baroclinic pressure gradients and surface waves these parameters can modify the horizontal and vertical flow in the near surface ocean making them of first order significance to a wide range of phenomena of broad practical and scientific import in this work an approximate green s function solution is found for a model of the frictional ocean surface boundary layer termed the generalized ekman or turbulent thermal wind balance the solution admits consideration of general more physically realistic forms of parameters than previously possible offering improved physical insight into the underlying dynamics closed form solutions are given for the wind driven flow in the presence of coriolis stokes shear a result of the surface wave field and thermal wind shear arising from a baroclinic

resonant near surface inertial oscillations in the northeastern gulf of mexico the inertial frequency is nearly diurnal at 30 n latitude which transects the northeastern gulf of mexico negom at this latitude near surface inertial oscillations can amplify due to resonance with diurnal wind forcing diurnal oscillations have also been attributed to diurnal tidal forcing in this region because tidal forcing wind forcing and inertial oscillations are nearly diurnal a unique series of comparative analyses are required to determine their relative influence on surface circulation by comparing surface currents obtained by hf radar to predictions of the inertial response to wind forcing and barotropic tidal currents it is found that diurnal oscillations in the negom were predominantly due to wind forced inertial oscillations in june 2010 the analyses provide a unique spatiotemporal perspective of inertial oscillations in the negom where there is evidence of propagation frequency and phase shifts and amplitude variability because inertial oscillations mix the ocean differently than the tides these results provide insight into how inertial oscillations potentially mixed oil from the deepwater horizon spill in june 2010 near diurnal oscillations during the winter were found to be predominantly due to tidal forcing when wind driven inertial oscillations were diminished due to a presumably deeper mixed layer

diagenetic controls on reservoir development and quality smackover formation of southwest alabama abstract abstract smackover reservoirs in southwest alabama are much more complex than those encountered in the central and western portions of the gulf coast basin this heterogeneity is a product of a complex history of diagenetic modification the diagenetic history can be divided into five separate stages 1 marine stage extensive grain micritization and precipitation of minor amounts of fibrous cement 2 meteoric vadose stage extensive dissolution of aragonitic grains 3 meteoric phreatic stage precipitation of granular and blocky cements 4 brine reflux stage extensive dolomitization and sulfate emplacement associated with refluxing of buckner brines and 5 burial stage grain to grain compaction of lithologies not stabilized by early cements stylolitization precipitation of poikilotopic calcite and dolomite cements minor dissolution of calcite associated with the introduction into the formation of undersaturated fluids hydrocarbon migration and sulfate replacement and cementation the diagenetic sequence varies dramatically over short distances in southwest alabama reflecting variation in paleotopography the products of this complex diagenetic history are heterogeneous reservoirs which consist of one or some combination of primary interparticulate moldic dolomitic intercrystalline and vuggy porosity primary interparticulate porosity is less common in southwest alabama than in the central and western portions of the gulf coast basin largely because of extensive compaction or early cementation where present however interparticulate reservoirs are characterized by moderate to high porosity and good permeability moldic porosity is produced by early fabric selective dissolution of aragonitic allochems and is associated with areas of subaerial exposure moldic reservoirs commonly have high porosity but low permeability and are generally productive only when permeability is enhanced by other pore types dolomitic intercrystalline porosity is common in the smackover of southwest alabama intercrystalline porosity alone however is seldom of reservoir quality and hydrocarbon production from dolomitized lithologies is generally dependent upon the coexistence of moldic or vuggy porosity vuggy porosity is the product of late non fabric selective dissolution of calcite vuggy pores are produced by solution enlargement of earlier formed interparticulate moldic or intercrystalline pores vuggy reservoirs are by nature composite and are characterized by moderate to high porosity and good permeability

submesoscale dynamics in the northern gulf of mexico part iii lagrangian implications abstractfour numerical simulations are used to characterize the impact of submesoscale circulations on surface lagrangian statistics in the northern gulf of mexico over 2 months february and august representative of winter and summer the role of resolution and riverine forcing is explored focusing on surface waters in regions where the water column is deeper than 50 m whenever submesoscale circulations are present the probability density functions pdfs of dynamical quantities such as vorticity and horizontal velocity divergence for eulerian and lagrangian fields differ with particles preferentially mapping areas of elevated negative divergence and positive vorticity the stronger the submesoscale circulations are the more skewed the lagrangian distributions become with greater differences between eulerian and lagrangian pdfs in winter lagrangian distributions are modestly impacted by the presence of the riverine outflow while increasing the model resolution from submesoscale permitting to sub